DE202015006182U1 - Brush Cutter - Google Patents

Abstract

A brushcutter, comprising: an operating rod, a rotary blade rotatably disposed at an end portion of the operating rod, an electric motor for driving the rotary knife, a rotation measuring portion that measures a physical quantity indicative of the rotational speed of the rotary knife, a control portion that sets a target value of Sets rotational speed to one of two or more target rotational speeds, and controls the rotation of the electric motor based on the physical quantity measured by the rotational measuring section such that the rotational speed of the rotary blade is the set target rotational speed and a load measuring section that measures the load applied to the electric motor, and an increase load threshold is set, which is for the other (s) target speed (s) except the highest target speed of the two or more target speeds based on the load measured by the load measuring section, the target speed to a higher target speed to switch, with a Senkungslastschwellenwert eing It is arranged to switch the target speed to a lower target speed for the other target speed (s) other than the lowest target speed of the two or more target speeds from the load measured by the load measuring section, the control section executing automatic target shift processing when the boost load threshold is set for the currently set target speed and the load measured by the load measuring section reaches or exceeds the boost load threshold, is switched to a higher target speed than the currently set speed, and if the set load threshold is set for the currently set speed and that from the load section measured load reaches or falls below the lowering load threshold, is switched to a lower target speed than the current target speed.

Description

Technical area

The present invention relates to a brushcutter.

General state of the art

Brushcutters in which a rotary blade is driven by an electric motor are widely used. The Japanese Patent Laid-Open Publication No. 2014-117267 discloses a brushcutter, wherein a user can switch a target rotational speed of a rotary knife by means of a controller operation. By operating the controller itself, the user can adjust the rotational speed of the rotary blade to the desired speed during grass cutting operations.

Documents of the prior art

Patent documents

• Patent document 1: Japanese Patent Laid-Open Publication No. 2014-117267

Brief description of the invention

Object of the present invention

At the brushcutter the Japanese Patent Laid-Open Publication No. 2014-117267 Although the setpoint speed can be changed as desired by means of a controller operation, it is not absolutely possible to set it to the setpoint speed which is suitable for the working state.

For example, if cutting work is performed at a low set speed to save power, there is a possibility that the target speed may need to be increased during work depending on the load condition (condition of the cutting object). conversely, when cutting work is performed at high set target speeds for work reasons, work may continue at a high speed depending on the load condition, although a lower speed would be sufficient. Such a situation causes excessive power consumption.

The present invention has been made in view of the above-mentioned problems, and its object is to provide a brushcutter, wherein cutting work without excessive power consumption can be adequately performed regardless of the load condition (condition of the cutting object).

Means for solving the problem

A brushcutter according to one aspect of the present invention includes a control rod, a rotary blade rotatably disposed at an end portion of the operating rod, an electric motor for driving the rotary blade, a rotation measuring portion that measures a physical quantity indicating the rotational speed of the rotary blade, a control portion adjusting a target value of the rotational speed to one of two or more target rotational speeds and controlling, based on the physical quantity measured by the rotational measuring section, the rotation of the electric motor such that the rotational speed of the rotary blade is the set target rotational speed and a load measuring section which applies the applied voltage to the electric motor Load measures.

In addition, an increase load threshold is set to switch the target speed to a higher target speed for the other target speed (s) other than the highest target speed of the two or more target speeds based on the load measured by the load measuring section.

In addition, a lowering load threshold is set which is to switch the target speed to a lower target speed for the other target speed (s) other than the lowest target speed of the two or more target speeds based on the load measured by the load measuring section.

The control section executes processing for automatic setpoint switching. The automatic setpoint switching processing is a processing in which, when the boost load threshold is set for the currently set target speed and the load measured by the load measuring section reaches or exceeds the boost load threshold, it is switched to a higher target speed than the currently set target speed, and when the lowering load threshold is set for the currently set target speed and the load measured by the load measuring section reaches or falls below the lowering load threshold, it is switched to a lower target speed than the current target speed.

In the brushcutter with the configuration described above, the target speed is not switched by the operation of a user but automatically according to the load applied to the motor. Thus, excessive power consumption is avoided, and at the same time, cutting work can be performed appropriately by rotating the rotary knife at an appropriate speed according to the load condition (condition of the cutting object).

In the brushcutter with the configuration described above, three or more target speeds may also be provided. By configuring to switch to one of three or more target speeds, a good compromise can be achieved between a reduction in power consumption and an improvement in work performance.

If three or more target speeds are provided, a configuration as described below is possible. A boost load threshold set for each of the three or more target speeds except for the highest target speed is set to a higher value, the higher the target speed to be switched to, and a lowering load threshold, for each of the three or more Set speeds other than the lowest target speed is set to a lower value, the lower the target speed to be switched to.

According to such a configured brushcutter, an even better compromise between low power consumption and performance can be achieved. In the brushcutter with the configuration described above, three target speeds can be provided. In this case, in the automatic setpoint switching processing, the control section may set the speed reference value to one of the three target speeds based on the load measured by the load measuring section.

By setting one of three types of target speeds according to the load, the work can be performed according to the load at the appropriate speed. Depending on the load fluctuation range to be expected in the work, the type of rotary knife used, the power and the like, it may be that at only two types of target speeds no work at the appropriate target speed are possible, while vice versa at z. B. four or more target speeds may be a functional excess, which is why in the number of three target speed can be appropriately prevented the example cases described above.

In addition, the brushcutter described above is configured as follows. For the target speeds for which an increase load threshold is set, an increase time threshold is set that judges the duration for which the load reaches or exceeds the increase load threshold, and for the target speeds for which a decrease load threshold is set, a decrease time threshold is set Duration for which the load reaches or falls below the subsidence load threshold. In the automatic set point switching processing for the currently set target speed, if an increase load threshold and an increase time threshold are set, and the duration for which the load measured by the load measuring section reaches or exceeds the increase load threshold stops for the increase time threshold or longer, the control section shifts the Set speed to a higher setpoint speed. When a lowering load threshold and a decreasing time threshold are set for the currently set target speed, and the duration for which the load measured by the load measuring section reaches or falls below the lowering load threshold continues for the lowering time threshold or longer, the control section shifts the target speed to a lower target speed.

In the brushcutter with the configuration described above, therefore, the target speed is not immediately switched when the load reaches the threshold or exceeds or falls below, but the target speed is only switched when the load threshold for a certain duration or exceeded becomes. In this way, the target speed can be switched according to the load at a reasonable time.

In addition, the brushcutter described above is configured as follows. The target speed for which the lowering-time threshold value is set is regarded as the decreasing output target value, and the target speed to be switched from the lowering output target value based on the lowering-time threshold value and which is lower than the lowering output target value is regarded as the target decreasing target value with the lowering-time threshold value set longer than the increasing-time threshold value which is set for the descent target setpoint and used when switching from the descent target setpoint to the descent output setpoint.

If the setpoint speed is lowered immediately when the load drops, there is a risk that the performance and ease of use for the operator may be affected, depending on the work situation. For example, in the course of cutting work, the load temporarily (for a very short time) drops and then increases again. It is to be assumed that in such a case, the operator desires that the current target speed be maintained even if the load is temporarily removed. By setting a longer time threshold for the case where the target speed is downshifted than for the case that it is upshifted, the ease of use (especially in cases where the load temporarily decreases) can be increased.

The brushcutter described above is also configured as follows. A target rotational speed for which the subsidence load threshold value is set is a subsidence target value, and a target rotational speed to be switched from the subsidence target value based on the subsidence load threshold and which is lower than the subsidence output target is considered the target descent target value with the subsidence load threshold set lower than the increase load threshold which is set for the descent target setpoint and used when switching from the descent target setpoint to the descent output setpoint.

When the increase load threshold for increasing the target speed and the lowering load threshold for decreasing the target speed to the original low target speed are the same, depending on the fluctuation state of the load, there is a possibility that the switching of the target speed occurs several times within a short time. By setting the sink load threshold lower than the increase load threshold, this problem can be prevented.

The brushcutter of the above-described configuration further includes a target speed notifying section for notifying information indicative of the target speed. In the brushcutter with the configuration described above, the operator can easily recognize the set target speed.

The brushcutter described above is further configured as follows. It has a target value setting input section for accepting an input for the target rotational speed. Further, as an operation mode, it has a fixed speed mode, wherein the target value of the speed is set to a target speed set by the target value setting input section, independently of the load measured by the load measuring section, and an automatic shift mode, the automatic target shift processing is executed. In addition, it has an operation mode setting input section serving to set one of the fixed speed mode or the automatic shift mode of operation. When the operation mode is set to the fixed speed mode via the operation mode setting input section, the control section does not execute the automatic set point switching processing and controls the electric motor such that the rotation speed is a target rotation speed set by the target value setting input section. However, when the automatic shift mode is set as the operation mode via the operation mode setting input section, the automatic set point switching processing is executed.

In the case of the brushcutter with the configuration described above, the operator can select whether the target speed should be switched automatically according to the load or whether he himself sets the desired setpoint speed for the work (fixed).

The brushcutter having the above-described configuration also has an operation mode notifying section for notifying information showing the set operation mode. With the brushcutter having the configuration described above, the operator can easily recognize the set operation mode.

In addition, the brushcutter described above is configured as follows. Several types of rotary blades can be selectively attached and detached. These plural types of rotary knives include at least one round disc-shaped rotary knife configured with saw teeth on its outer circumference and a rotary knife having a string-shaped member, wherein the string-shaped member rotates in a tensioned state due to the rotation of the electric motor and cuts the cutting object can be made by the rotating cord-shaped element is applied to the cutting object.

In the brushcutter with the above-described configuration, the appropriate rotary blade can be selected depending on the kind or condition of the cutting object. The brushcutter with the configuration described above is configured with a rechargeable detachable rechargeable battery and may be configured such that the electric motor can be powered and operated by the rechargeable battery when the rechargeable battery is attached. According to this configuration, cutting work can be performed adequately while suppressing excessive consumption of battery power.

Brief description of the figures

Show it:

1 a perspective view of a grass cutter according to an embodiment;

2 a sectional view of a front portion of the grass cutter;

3 an enlarged plan view of an operation / display unit;

4 a diagram of the electrical configuration of the grass cutter;

5 an explanatory view of a switching pattern of the speed mode, as may occur in the automatic switching mode;

6 an explanatory view of an operating example of the grass cutter 1 in automatic switching mode;

7 a flowchart of a part of a main processing;

8th a flow chart of part of the main processing (continued from 7 ); and

9 a perspective view of a grass cutter to which a nylon cord cutter is attached.

Embodiment of the invention

Hereinafter, an embodiment to which the present invention has been applied will be described with reference to the drawings.

(1) Configure the grass cutter 1

As in 1 shown has a grass cutter 1 the present embodiment, a main pipe 2 , a control unit 3 , a drive unit 4 and a carrying handle 7 on. The main pipe 2 is formed in the form of an elongated hollow rod. At the rear end of the main pipe 2 is a control unit 3 provided, and at the front end of the main pipe 2 is a drive unit 4 intended.

A rotary knife 5 is detachable and rotatable on the drive unit 4 appropriate. The rotary knife 5 is a work tool for cutting cutting objects such as grass or small-diameter branches (hereinafter "grass, etc."). This in 1 shown rotary knives 5 is a so-called circular knife. That is, the rotary knife 5 is made of metal and has a round shape, and saw teeth are formed on its entire outer periphery. On the individual teeth hard tips are placed.

At the front end of the main pipe 2 is a cover 6 intended. The cover 6 is designed to prevent the grass, etc., from the rotary blade 5 to the operator (user of the grass cutter 1 ) is thrown.

Inside the drive unit 4 is how in 2 shown as a drive source for driving the rotary knife 5 an electric motor (hereafter "motor") 31 arranged. At the front end of a rotary shaft 41 of the motor 31 is a drive gear 42 provided, which coincides with the rotation of the rotary shaft 41 rotates. The drive gear 42 is with a driven gear 43 toothed. The driven gear 43 is at one end of an output shaft 44 intended. At the other end of the output shaft 44 is a rotary knife 5 detachably attached. If the engine 31 (or more precisely, the rotary shaft 41 ) turns, this rotation is via the drive gear 42 and the driven gear 43 on the output shaft 44 transfer. The output shaft 44 in turn rotates in one piece with the attached rotary blade 5 ,

When the rotary knife 5 turning from the engine 31 is driven, the outer peripheral part of the rotary knife 5 attached to the grass, etc., whereby the grass etc. can be cut and grass cutting work can be performed.

In the present embodiment, the engine is 31 a brushless motor. At the rear end of the engine 31 is also a sensor board 45 intended. On the sensor board 45 is an angle sensor 36 for measuring the rotation angle of the motor 31 appropriate. At the angle sensor 36 In the present embodiment, it is a known Hall sensor using a Hall element. One from the angle sensor 36 output signal, which is the rotation angle of the motor 31 indicates (angle measurement signal), is in a control section 32 within the control unit 3 (please refer 4 ) fed.

A carrying handle 7 is adjacent to a central position in the longitudinal direction of the main pipe 2 with the main pipe 2 connected. The carrying handle 7 is held by the operator when using the grass cutter 1 Works. The carrying handle 7 is a frame grab handle in the present embodiment, but this is only an example, and it may be another type of carrying handle. For example, a U-shaped carrying handle, a carrying handle with two handles, a rear end carrying handle or the like may be used.

Behind the position where the carrying handle 7 with the main pipe 2 is connected, is an operation / display unit 8th intended. At a position behind the one at the main pipe 2 the operation / display unit 8th is provided, are a blocking switch 9 and a power switch 10 intended.

The operating switch 10 is a switch that the operator operates to rotate or stop the rotary knife 5 to instruct. By the operator in a state in which an on / off switch 21 (please refer 3 ) is turned on and the grass cutter 1 was started (or more precisely, a control section 32 (please refer 4 ) was started), the operation switch 10 pulled pulling and thereby the operation switch 10 turns on, becomes the engine 31 powered, so that the engine 31 (or the rotary knife 5 ) turns.

The lock switch 9 is a switch with which the switch-on operation of the operation switch 10 mechanically locked. When the lock switch 9 is not pressed, the lock switch engages 9 in the operating switch 10 and limits the movement of the operation switch 10 one, leaving the power switch 10 can not be operated. To the operation switch 10 to turn on, the power switch must 10 in the on state of the lock switch 9 be operated.

The at the rear end of the main pipe 2 provided control unit 3 has a housing 11 and a battery pack 12 on. The battery pack 12 is detachable at the rear section of the housing 11 attachable configured.

In the battery pack 12 is a battery 34 added. The battery 34 is a repeatedly rechargeable power source that contains the individual elements in the housing 11 and the engine 31 powered. The battery 34 The present embodiment is constructed by two lithium-ion batteries, but this is just one example. The rated voltage of the battery 34 For example, in the present embodiment, it is 18V, but this too is just one example.

At the operation / display unit 8th several switches and display sections are provided. More specific are on the control / display unit 8th , as in 3 shown an on / off switch 21 , a mode switcher 22 , a speed display section 23 and a status indicator lamp 24 intended. The speed display section 23 indicates a low speed indicator light 26 , a middle speed indicator light 27 and a high speed indicator lamp 28 on.

The low speed indicator light 26 , the middle speed indicator light 27 , the high speed indicator light 28 and the status indicator lamp 24 are each a light emitting diode (LED) in the present embodiment. However, other display means may be used instead of an LED.

The on / off switch 21 is a switch with which the grass cutter 1 is brought into the usable state. When the operator turns the on / off switch 21 turns on, starts the grass cutter 1 , More precisely, the control section starts 32 in the case 11 (please refer 4 ). If the operator after starting the control section 32 the operation switch 10 turns on, the rotary knife rotates 5 so that grass cutting, etc. are possible. Will the on / off switch 21 switched off, so stops the operation of the control section 32 on, and the grass cutter 1 is no longer operational.

In the present embodiment, there are two operation methods of the on / off switch 21 in front. One is a long press and the other is a short press. The long press is an operation with the on / off switch 21 for a certain period of time (for example 2 seconds), and the short press is an operation with the on / off switch 21 shorter than the specified duration is pressed. In the present embodiment, the "turning on" and "turning off" of the on / off switch refers 21 each on the long press as opposed to the short press. So by the on / off switch 21 switched on (long pressed), the control section 32 be started, and by the on / off switch 21 in the started state is switched off (long pressed), the operation of the control section 32 be stopped.

In addition to the function of starting and stopping the control section 32 indicates the on / off switch 21 Also, a function for switching the speed mode, wherein the switching of the speed mode by briefly pressing the on / off switch 21 he follows.

The mode switch 22 is a switch that the operator operates to control the operation mode of the grass cutter 1 to set to one of the fixed speed mode and the automatic shift mode. The following describes operation mode and speed mode. At the grass cutter 1 In the present embodiment, the engine 31 controlled such that the speed of the rotary knife 5 coincides with a predetermined speed set in advance. At the grass cutter 1 The present embodiment is thus as a control method of the engine 31 a speed feedback control applied.

To control the engine 31 It is necessary to set a target speed for the speed of the rotary knife 5 adjust. For example, may also be a target speed for the speed of the motor 31 be set. As long as the speed of the rotary knife 5 is a directly or indirectly represented physical quantity, it can be determined at will, for which physical quantity should be set to the desired value. That is, as long as the result is a control that the rotational speed of the rotary knife 5 controls to a desired speed (setpoint speed), it can be set at will, which physical size is measured directly and which setpoint is to be set for the physical size.

The setpoint speed changes according to the speed mode. In the present embodiment, there are provided three types of speed modes, namely, a low-speed mode, a middle-speed mode, and a high-speed mode, and adjustment to and operation of one of these speed modes is possible. One target speed is set for each of three types of speed modes provided, with the target speed of the low-speed mode being the lowest and the set speed of the high-speed mode being the highest. More specifically, in the present embodiment, the target speed of the low-speed mode is set to 3500 rpm, the target speed of the intermediate-speed mode is set to 4500 rpm, and the target speed of the high-speed mode is set to 6000 rpm.

The target speed in the low-speed mode does not necessarily provide load freedom in the present embodiment. For example, the target speed of the low-speed mode may be set to a speed, for example, a very small amount of grass, etc. may be cut, and thus, work may be performed at a certain load.

The specific setting of the target speeds of the individual speed modes can be set as desired, and the numbers given above for the target speed are examples only. However, it is practical in terms of work performance when the target speed in the lowest speed mode is set to a target speed at which a minimum of work can be done. For example, if it is preferable that the target speed at which a minimum of work can be performed is 3000 rpm or more, the target speed for the low-speed mode may be set to 3000 rpm as stated above, for example.

At the grass cutter 1 There are two types of operating modes, namely a fixed speed mode and an automatic shift mode. The fixed speed mode is an operating mode in which the operator can set the speed mode to perform work himself to the desired mode. The automatic shift mode is an operating mode in which the speed mode is automatically switched according to the load.

When starting the control section 32 For example, as the initial setting, the fixed speed mode is set as the operation mode, and the speed mode is set to the high speed mode. The definition of the initial settings (settings of the individual modes at the start) can be done as desired.

While the fixed speed mode is set as the operating mode, the operator may depress the on / off switch by briefly pressing 21 switch the speed mode. Specifically, with each brief press of the on / off switch 21 the speed mode in the order of high-speed mode → low-speed mode → medium-speed mode → high-speed mode → low-speed mode → ... switched. This order is just an example.

By the operator switching the mode switch 22 When activated, it can set the operating mode to the fixed speed mode or the automatic shift mode. More specifically, the operation mode is changed with each short press of the mode switch 22 changed.

When the operating mode is switched from the automatic shift mode to the fixed speed mode, the speed mode is set to the high-speed mode, which is the initial setting value. However, this is just an example, and it is also possible to set the speed mode that was set at the last setting of the fixed speed mode (before switching to the automatic shift mode).

When the operation mode is switched from the fixed speed mode to the automatic shift mode, the speed mode is set to the fixed speed mode having the lowest target speed. While the operation switch 10 is turned on and the engine 31 turns, the speed mode will automatically be the same as that of the motor 31 applied load switched.

The speed display section 23 is intended to inform the operator of the operating mode and the speed mode. When the operation mode is set to the fixed speed mode, the indicator lights are lit. 26 to 28 in a light pattern corresponding to the set speed mode. Specifically, the lower speed indicator lamp lights up 26 when the speed mode is set to the low speed mode. When the speed mode is set to the medium speed mode, the low speed indicator light will be on 26 and the middle speed indicator light 27 , When the speed mode is set to the high speed mode, the low speed indicator light will be on 26 , the middle speed indicator light 27 and the high speed indicator light 28 , The specified light pattern in the fixed speed mode is merely an example, and it may be a different light pattern.

When the operation mode is set to the automatic switching mode, the lighting pattern differs depending on whether the operation switch 10 is turned on or not (so whether the engine 31 is powered or not). While the operation switch 10 is off, the indicator lights are lit. 26 to 28 in a light-emitting pattern indicating that the operating mode is set to automatic switching mode. For example, a light pattern is conceivable, with the indicator lights 26 to 28 one after the other in a certain cycle (for example, 0.5 seconds) light up. When the operation switch 10 is turned on, however, the light pattern corresponding to the speed mode (that is, the light pattern in the case that the operation mode is set to the fixed speed mode) appears.

The status indicator lamp 24 lights according to the operating state of the grass cutter 1 , A description of the lighting timing and the lighting pattern of the status indicating lamp 24 eliminated.

(2) Electrical configuration of the grass cutter 1

Next, let's look at the block diagram 4 the electrical configuration of the grass cutter 1 to be discribed. As in 4 shown, points the grass cutter 1 a control section 32 , a converter 33 and a power supply circuit 35 on. If the battery pack 12 at the control unit 3 is attached, the battery voltage of the battery 34 in the battery pack 12 to the power supply circuit 35 and the converter 33 created.

The operating switch 10 , the on / off switch 21 , the mode switch 22 , the speed indicator section 23 and the status indicator lamp 24 connected to the control / display unit 8th are provided are electrically connected to the control section 32 connected. The operating switch 10 , the on / off switch 21 and the mode switch 22 in each case a signal indicating the operating state, feed into the control section 32 one. The speed display section 23 and the status indicator lamp 24 be from the control section 32 controlled.

The control section 32 judged by the operation switch 10 fed signal the on / off state of the operating switch 10 and performs control according to this on / off state. In addition, the control section judges 32 on the basis of the operating switch 10 fed signal the operating state of the on / off switch 21 (long press or short press) and performs control according to this operating state. For example, if it is judged that the on / off switch 21 long pressed, it starts itself or turns off. The control section 32 is configured to control the operating state of the on / off switch 21 even when he has turned himself off. When the operation mode is set to the fixed speed mode, the on / off switch turns on 21 also with each short press the speed mode.

In addition, the control section judges 32 using the mode switch 22 fed signal the operating state of the mode switch 22 (long press or not) and performs control according to this operating state. More specifically, the operation mode is changed with each long press of the mode switch 22 switched.

There is also an angle sensor 36 that is attached to the drive unit 4 is provided, electrically connected to the control section 32 connected. The angle sensor 36 feeds a signal into the control section 32 a, which is the rotation angle of the engine 31 displays. The control section 32 recognizes by the angle sensor 36 fed signal the rotational position of the motor 31 and recognizes the speed of the motor based on the change in the rotational position 31 , As the speed of the engine 31 and the speed of the rotary knife 5 in proportional relationship means measuring the speed of the motor 31 also indirectly measuring the speed of the rotary knife 5 ,

The control section 32 is configured in the present embodiment by a microcomputer having a CPU, a memory, a timer, an A / D converter and so on. In the memory in the control section 32 are various programs and data for controlling the engine 31 , the speed display section 23 , the state indicator light 24 etc. stored. The programs stored in memory also include the program of 7 and 8th illustrated main processing. A CPU in the control section 32 performs various functions based on the various programs and data stored in memory.

The power supply circuit 35 generated as long as the battery 34 Battery voltage is applied by lowering the battery voltage, a DC control voltage with a certain voltage value (eg 5 V). The from the power supply circuit 35 generated control voltage is used as the operating voltage source for the individual parts including the control section 32 used.

When the control section 32 by turning on the on / off switch 21 has been switched on, it calculates as soon as the operation switch 10 is turned on, a degree of modulation of the current for rotating the motor 31 and outputs a control signal indicative of this level of modulation to the converter 33 out.

The converter 33 has, for example, a three-phase bridge circuit with six semiconductor switching elements. By the converter 33 according to the degree of control, that of the control section 32 fed control signal indicates that switches individual switching elements of the three-phase bridge circuit, the motor 31 supplied with a current corresponding to the Aussteuerungsgrad (in the present embodiment, three-phase current).

At the Stromleitweg from the battery 34 to the engine 31 is a current sense resistor 37 for measuring the engine 31 flowing current (hereinafter "load current I") provided. The voltage at both ends of the current sense resistor 37 is from an amplifier 38 is amplified, and the boosted voltage is input to the control section as a current measurement signal representing the load current I 32 fed.

By the control section 32 that of the amplifier 38 When the injected current measurement signal undergoes an AD conversion, it determines the value of the load current I. The control section 32 uses the determined load current I in a main processing described below. The value of the load current I depends on the value of the motor 31 applied load. While with the grass cutter 1 Namely, grass cutting work, etc., changes depending on the condition of the grass or other cutting object, that of the engine 31 applied load (more precisely, to the engine 31 from external elements such as grass, etc. via the rotary knife 5 applied load in the direction of rotation of the motor 31 ). The change in load manifests itself as a change in the load current I of the motor 31 , Measuring the load current I thus corresponds to measuring the size of the load.

When the operation mode is set to the automatic shift mode, the control section switches 32 according to the engine 31 applied load automatically reverses the speed mode. To achieve this, the control section must 32 Know when the load is large, in the present embodiment, by determining the load current I, the load of the motor 31 is measured indirectly.

(3) Description of automatic shift control

Next, the automatic shift control described by the control section will be described 32 is executed as long as the operating mode is set to the automatic switching mode. When the operation mode is set to the automatic shift mode, the speed mode is automatically switched according to the load.

As the speed mode switching conditions for automatically switching the speed mode, in the present embodiment, an increase condition A, an increase condition B, a decrease condition A, and a decrease condition B are set. The increasing condition A is as in 5 a condition for switching the speed mode from the low-speed mode to the medium-speed mode. As the increasing condition A, specifically, a boost current threshold A, an increase determination time A, and a masking time A are set.

The satisfaction of the increasing condition A means that the state in which the load current I reaches or exceeds the boost current threshold value A lasts for the increase determination time A or longer. When the speed mode is set to the low-speed mode and the increase condition A is satisfied, the speed mode is automatically switched from the low-speed mode to the medium-speed mode.

Immediately after switching on the engine 31 flows an extremely high surge current. When judging the satisfaction of the increasing condition A for this surge current, it is judged that there is a high load on the engine 31 although there is actually only a small load applied to it and it is erroneously judged that the increasing condition AA is satisfied. Therefore, for the increasing condition A, a masking time A is set, and only when after starting the engine 31 the masking time A has elapsed, it is judged from the load current I whether or not the increasing condition A is satisfied.

The boost current threshold A, the increase determination time A, and the masking time A may each be set as needed, for example, in the present embodiment, the boost current threshold A (IuA) is 3.3A, the increase determination time A (TuA) is 50ms, and the masking time A (TmA) is set to 2000 ms.

The increasing condition B is as in 5 a condition for switching the speed mode from the middle speed mode to the high speed mode. As the increasing condition B, specifically, a boost current threshold B, an increase determination time B, and a masking time B are set. The boost current threshold B is a value higher than the boost current threshold A of the boost condition A.

The satisfaction of the increasing condition B means that the state in which the load current I reaches or exceeds the boost current threshold B for the increase determination time B or longer lasts. When the speed mode is set to the medium speed mode and the increasing condition B is satisfied, the Speed mode automatically switched from mid-speed mode to high-speed mode.

Immediately after switching the set speed of the engine 31 flows as well as when starting an extremely high surge current. Therefore, even in the increasing condition B, a masking time B is set, and it is judged from the load current I whether the increasing condition B is satisfied or not after switching the speed mode from the middle speed mode to the high speed mode the masking time B has elapsed.

The boost current threshold B, the increase determination time B, and the masking time B may each be set as needed, for example, in the present embodiment, the boost current threshold B (IuB) is set to 8A, the increase determination time B (TuB) to 100ms, and the masking time B (TmB ) is set to 1000 ms.

The subsidence condition B is as in 5 a condition for switching the speed mode from the high-speed mode to the medium-speed mode. As the subsidence condition B, specifically, a subsidence current threshold B and a subsidence determination time B are set. The lowering current threshold B is a lower value than the increasing current threshold B of the increasing condition B. The decreasing determination time B, in turn, is a longer time than the increasing determination time B of the increasing condition B.

Fulfillment of the subsidence condition B means that the state in which the load current I reaches or falls below the subsidence current threshold B continues for the subsidence determination time B or longer. When the speed mode is set to the high speed mode and the lowering condition B is satisfied, the speed mode is automatically switched from the high speed mode to the middle speed mode.

The subsidence current threshold B and the subsidence determination time B may each be set as needed, for example, in the present embodiment, the subsidence current threshold B (IdB) is set to 6A and the subsidence determination time B (TdB) is set to 2000ms.

The subsidence condition A is as in 5 a condition for switching the speed mode from the middle speed mode to the low speed mode. As the subsidence condition A, specifically, a subsidence current threshold A and a subsidence determination time A are set. The lowering current threshold A is a lower value than the lowering current threshold B and a lower value than the increasing current threshold A of the increasing condition A. The decreasing determination time A, in turn, is longer than the increasing determination time A of the increasing condition A.

Fulfillment of the subsidence condition A means that the state in which the load current I reaches or falls below the subsidence current threshold value A continues for the subsidence determination time A or longer. When the speed mode is set to the middle speed mode and the lowering condition A is satisfied, the speed mode is automatically switched from the middle speed mode to the low speed mode.

The subsidence current threshold A and the subsidence determination time A may each be set as required, for example, in the present embodiment, the subsidence current threshold B (IdA) is set to 2.8A and the subsidence determining time A (TdA) is set to 2000ms.

When switching between the low-speed mode and the medium-speed mode, the lowering lowering determination time A serving for lowering is set longer than the increasing-amount determining time A for increasing. When switching between the middle-speed mode and the high-speed mode, the lowering lowering determination time B serving for lowering is set longer than the raising determination time B for increasing.

The decrease determination time is set longer than the increase determination time for the following reasons. During cutting work, load fluctuations occur relatively frequently, with the load temporarily decreasing and then rising again. In the course of the cutting work, the load suddenly decreases sharply at irregular intervals and then again, for example in the event that the operator has the rotary knife 5 intentionally removed from the grass, etc. for a moment. If the speed mode is automatically lowered while working every time the load is temporarily lowered, the performance and ease of use will deteriorate. By the grass cutter 1 In the present embodiment, the lowering determination time is set longer than the increase determination time, switching to a lower speed mode contrary to the will of the operator is inhibited.

6 FIG. 15 shows an operation example in the case where the operation mode is set to the automatic shift mode and the operation switch 10 is turned on. In 6 the upper part shows the actual speed and setpoint speed of the rotary knife 5 while the lower part indicates the load current I.

As in 6 is shown in the initial state of the automatic shift mode as the speed mode, the low-speed mode. When the operation switch 10 is switched on, the engine starts 31 and is controlled in low speed mode. That is, the target rotational speed is set to a rotational speed corresponding to the low-speed mode (3000 rpm in the present embodiment), and the actual rotational speed of the rotary blade 5 and the target speed match.

As in 6 An extremely high surge current flows immediately after starting, and until the masking time A (TmA) has elapsed, no judgment is made on the basis of the load current I whether or not the increase condition A is satisfied. When, after the lapse of the masking time A (TmA), the load increases and the load current I reaches or exceeds the boost current threshold value A (IuA) and this state continues for the duration of the increase determination time A (TuA) or longer, the increase condition A is satisfied and the rotation speed mode is satisfied is switched from the low-speed mode to the medium-speed mode. That is, the target speed is switched from 3000 rpm to 4500 rpm.

Immediately after switching the speed mode from the low speed mode to the medium speed mode, as shown in FIG 6 shown, an extremely high surge current, and after switching to the medium-speed mode, a judgment is made only on the basis of the load current I whether the increase condition A is satisfied or not, when the masking time B (TmB) has elapsed. When, after the lapse of the masking time B (TmB), the load further increases and the load current I reaches or exceeds the boost current threshold B (IuB), and this state continues for the duration of the increase determination time B (TuB) or longer, the boost condition B is satisfied Speed mode is switched from mid-speed mode to high-speed mode. That is, the target speed is switched from 4500 rpm to 6000 rpm.

When, after switching the speed mode from the mid-speed mode to the high-speed mode, the load decreases and the load current I reaches or falls below the decrement current threshold value B (IdB), and this state continues for the duration of the decrement determination time B (TdB) or longer, For example, the lowering condition B is satisfied, and the speed mode is switched from the high-speed mode to the middle-speed mode. That is, the target speed is switched from 6000 rpm to 4500 rpm.

When, after switching the speed mode from the high-speed mode to the medium-speed mode, the load further decreases and the load current I reaches or falls below the lowering current threshold value A (IdA), and this state continues for the duration of the lowering determination time A (TdA) or more , the subsidence condition A is satisfied and the speed mode is switched from the middle speed mode to the low speed mode. That is, the target speed is switched from 4500 rpm to 3000 rpm.

(4) Main processing

A main processing for executing the control section 32 automatic switching is performed by reference to 7 and 8th to be discribed. The control section 32 performs the main processing 7 and 8th off when it turns on by turning on the on / off switch 21 is started.

The control section 32 judges the setting state of the operation mode at the beginning of the main processing in S110. In the present embodiment, immediately after starting the control section 32 as the initial setting, the fixed speed mode is set as the operating mode, and as the speed mode, the low speed mode is set.

When the operation mode is set to the fixed speed mode, a transition is made to S120. In S120, a lighting of the speed display section 23 effected in accordance with the set speed mode. For example, in the case of the fixed speed mode and the medium speed mode, the low speed indicator lamp lights up 26 and the middle speed indicator light 27 ,

In S130, it is judged whether the operation switch 10 is turned on. When the operation switch 10 is not turned on (S130: No), it returns to S110. When the operation switch 10 is turned on (S130: Yes), in S140, the rotation of the motor becomes 31 controlled such that the speed of the rotary knife 5 is the setpoint speed that corresponds to the set speed mode. After processing S140, return to S120.

If the operation mode is set to the automatic shift mode in S110, S150 is continued. In S150, the speed display section is caused to be 23 in the illuminated pattern that indicates the automatic switching mode. In S160 it is judged whether the operation switch 10 is turned on. When the operation switch 10 is not turned on (S160: No), it returns to S110. When the operation switch 10 is on (S160: Yes), the speed mode is set to the low-speed mode in S170. That is, when starting the engine in the automatic shift mode, the speed mode is set to the low-speed mode.

In S180, a lighting of the speed display section 23 according to the set speed mode (here the low speed mode). In S190, the rotation of the motor 31 controlled such that the speed of the rotary knife 5 is the setpoint speed that corresponds to the set speed mode. In S200, the measurement of time starts after turning on the operation switch 10 elapses.

In S210, it is judged by the time elapsed since the power-on whether or not since the operation switch was turned on 10 the masking time A has elapsed. If the masking time A has not elapsed (S210: No), it returns to S160. When the masking time A has elapsed (S210: Yes), the measurement of the time elapsed since the power-on is stopped and its counter is reset, and a transition is made to S220. The processing from S220 is as in 8th shown.

In S220, it is judged whether a condition for switching from the currently set speed mode to another speed mode is satisfied. For example, when the rotational speed mode is set to the low-speed mode, it is judged from the load current I whether the cranking condition A is satisfied. In turn, when the speed mode is set to the middle-speed mode, it is judged from the load current I whether the increase condition B or the decrease condition A is satisfied. For example, when the speed mode is set to the high-speed mode, it is judged from the load current I whether the lowering condition B is satisfied.

If no condition for switching from the set speed mode to another speed mode is satisfied (S220: No), a transition is made to S230. In S230, the rotation of the engine 31 controlled such that the speed of the rotary knife 5 is the setpoint speed that corresponds to the set speed mode. In S240, it is judged whether the operation switch 10 is turned on. When the operation switch 10 is switched on (S240: Yes), a return to S220 takes place. When the operation switch 10 is not switched on (S240: No), a return to S110 takes place ( 7 ).

When a condition for switching from the set speed mode to another speed mode is satisfied (S220: Yes), a transition is made to S250. In S250, the speed mode is switched according to the satisfied speed mode switching condition. For example, when the medium speed mode is set and the increasing condition B is satisfied, the speed mode is switched to the high speed mode. However, if, for example, the medium speed mode is set and the lowering condition A is satisfied, the speed mode is switched to the low speed mode.

In S260, a lighting of the speed display section 23 according to the set speed mode (here the low speed mode). In S270, it is judged whether the switching of the speed mode in S250 has been an increase, that is, whether the target speed has been increased. If no increase has taken place (that is, a decrease has occurred) (S270: No), a transition is made to S230. If an increase has occurred (S270: Yes), a transition is made to S280.

In S280, measuring the time since switching the speed mode starts. In S290, the rotation of the engine 31 controlled such that the speed of the rotary knife 5 is the setpoint speed that corresponds to the set speed mode.

In S300, it is judged from the time elapsed since the switching whether the masking time B has elapsed since switching the speed mode. If the masking time B has not elapsed (S300: No), it is judged in S310 whether the operation switch 10 is turned on. When the operation switch 10 is switched on (S310: Yes), the system returns to S290. When the operation switch 10 is not switched on (S310: No), a return to S110 takes place ( 7 ). If the masking time B has elapsed in S300 since the changeover of the speed mode (S300: Yes), the measurement of the elapsed time since the switchover is stopped and its counter is reset, and a return is made to S220. Although in 7 and 7 [sic!] not shown, in the event that after turning on the operation switch 10 and starting the engine 31 by means of power supply of the operating switch 10 is turned off, the power to the engine 31 interrupted and the rotation of the engine 31 stopped.

(5) Variations of the rotary knife 5

At the grass cutter 1 In the present embodiment, instead of the rotary knife configured as a circular blade 5 various other types of rotary blades on the drive unit 4 be attached and used. A kind of rotary knife attached to the drive unit 4 attachable is a nylon cord cutter. 9 shows a grass cutter 1 , where as a rotary knife a nylon cord cutter 51 is appropriate.

The nylon cord cutter 51 has a substantially cylindrical coil 52 and one from the coil 52 picked up nylon cord 53 on. When the nylon string cutter 51 at the output shaft 44 the drive unit 4 (please refer 2 ) is the nylon cord cutter 51 as well as that 1 shown rotary knives 5 by means of the rotary drive by the motor 31 rotatable.

In two places on a side surface of the coil 52 that the nylon cord cutter 51 forms are holes for leading out the nylon cord 53 formed, and the nylon cord 53 is led out of these two holes. 9 shows from the two holes on the coil 52 one from which the nylon cord 53 led out. If during the rotation of the nylon string cutter 51 the from the coil 52 led out nylon cord 53 is applied to grass, etc., the grass, etc. using the nylon cord 53 get cut.

A comparison of the performance of the nylon cord cutter and the performance of the circular blade shows that at the same speed, the performance of the blade is higher than that of the nylon cord cutter (thus making cutting easier). For example, in the case of the nylon cord cutter, if the speed mode is the low-speed mode (target speed 3000 rpm), there is a possibility that sufficient cutting performance can not be obtained while the circular blade has a comparatively sufficient cutting performance even in the low-speed mode can be obtained.

(6) Effect of the embodiment

According to the grass cutter described above 1 In the present embodiment, when the operation mode is set to the automatic shift mode, the speed mode switches to the engine without operator's operation 31 applied load automatically. Thus, excessive power consumption is avoided, and at the same time, cutting work can be done appropriately by the rotary knife 5 is rotated at a suitable speed according to the load condition (condition of the cutting object). Because the grass cutter 1 the present embodiment is configured in particular such that it by means of electricity from a battery 34 is operated, it is particularly in terms of the point of a lower discharge of the battery 34 effective.

In the present embodiment, three types of speed modes are provided, namely, the low speed mode, the middle speed mode, and the high speed mode. However, if there are only two types of speed modes, there is a possibility that the work can not be performed properly depending on the load. Again, if there are four or more types of speed modes, there is a possibility that the processing load of the control section 32 increases and affects other processing operations or increases power consumption. Three types of speed modes are thus one way of optimally balancing the processing load of the control section 32 and achieve job performance.

In the present embodiment, in the automatic shift mode, the necessity of switching the speed mode is not judged solely by a size comparison of the load current I and a current threshold. In the present embodiment, it is judged that a condition for switching the speed mode (switching to a higher-speed mode) is satisfied when the state in which the load current reaches or exceeds the boost current threshold value lasts for an increase determination time or longer. It is also judged that a condition for switching the speed mode (switching to a lower-speed mode) is satisfied when the state in which the load current reaches or falls below the lowering current threshold value lasts for a lowering determination time or longer. In this way, the speed mode can be switched according to the load at an appropriate time.

When switching between the low-speed mode and the medium-speed mode, the lowering lowering determination time A serving for lowering is set longer than the increasing-amount determining time A for increasing. When switching between the middle-speed mode and the high-speed mode, the lowering lowering determination time B serving for lowering is set longer than the raising determination time B for increasing. Thus, by setting the lowering determination time for switching from one to the other between two speed modes longer than the increase determination time for switching from one to the other, it can be inhibited that the speed mode is lowered against the will of the operator.

Also, in the present embodiment, the same current threshold is not used for the current threshold when upshifting and downshifting, and so-called hysteresis is provided instead. In this way, it can be prevented that, due to the fluctuation state of the load, the switching of the speed mode takes place several times within a short time. However, a hysteresis for the current threshold is not mandatory.

When the operation mode is set to the fixed speed mode, the speed display section is lit. 23 in a light pattern corresponding to the set speed mode. On the other hand, when the operation mode is set to the automatic shift mode, the speed display section is lit. 23 as long as the power switch 10 is off, in a light-emitting pattern indicating that the operating mode is the automatic switching mode, and during the operating switch 10 is switched on, in a light pattern that corresponds to the speed mode. Using the speed display section 23 with the three indicator lights 26 . 27 . 28 So can the setting state of various modes on the grass cutter 1 being checked.

Further embodiments

• (1) Die an den Motor 31 angelegte Last muss nicht zwingend anhand des zum Motor 31 fließenden Stroms (Laststrom I) gemessen werden. Die an den Motor 31 angelegte Last kann auch in anderen Verfahren als mittels des Laststroms I gemessen werden.
• (2) Es ist nicht zwingend notwendig, das Umschalten des Betriebsmodus und das Umschalten des Drehzahlmodus mithilfe eines Druckschalters (Ein/Aus-Schalter 21, Modusumschalter 22) durchzuführen. Es ist auch möglich, die Modusumschaltung durch andere Eingabemittel als einen Druckschalter durchzuführen. Beispielsweise kann die Modusumschaltung mithilfe eines Schalters des Reglertyps erfolgen.
• (3) Im automatischen Schaltmodus kann die obere Grenze für den Drehzahlmodus auch durch den Bediener selbst eingestellt werden. Indem beispielsweise die obere Grenze für den Drehzahlmodus auf den Modus mit mittlerer Drehzahl eingestellt wird, kann erreicht werden, dass der Drehzahlmodus zwischen dem Modus mit niedriger Drehzahl und dem Modus mit mittlerer Drehzahl umgeschaltet wird, ohne dass in den Modus mit hoher Drehzahl umgeschaltet wird.

In the above, an embodiment of the present invention has been described, but the present invention is not limited to this embodiment and can be embodied in various ways.

• (1) The to the engine 31 applied load does not necessarily have to be based on the engine 31 flowing current (load current I) are measured. The to the engine 31 applied load can also be measured in other methods than by means of the load current I.
• (2) It is not necessary to switch the operating mode and to switch the speed mode using a pressure switch (On / Off switch 21 , Mode switch 22 ). It is also possible to perform the mode switching by other input means than a pressure switch. For example, the mode switching can be done by means of a switch of the regulator type.
• (3) In automatic shift mode, the upper limit for the speed mode can also be set by the operator himself. For example, by setting the upper limit for the speed mode to the middle speed mode, it is possible to switch the speed mode between the low speed mode and the medium speed mode without switching to the high speed mode.

• (4) Die Anzahl der Arten von Drehzahlmodi ist nicht auf drei Arten beschränkt. Es können auch zwei Arten oder vier oder mehr Arten vorliegen. Bezüglich der Festlegung der Anzahl von Arten von Drehzahlmodi sind mehrere Möglichkeiten denkbar, und es ist beispielsweise eine selektive Einstellung gemäß den Arten von Drehmessern möglich. So gibt es einerseits Drehmesser, bei denen es beim Schneiden von Gras usw. besser ist, mit einer Drehzahl zu arbeiten, die dem Modus mit hoher Drehzahl entspricht (beispielsweise der in 9 gezeigte Nylonschnurschneider 51, im Folgenden auch als „erster Drehmessertyp” bezeichnet), während bei anderen Drehmessern auch bei einer Drehzahl, die dem Modus mit mittlerer Drehzahl oder dem Modus mit niedriger Drehzahl entspricht, eine ausreichende Arbeitsleistung erlangt werden kann (beispielsweise mit dem Kreismesser, im Folgenden auch als „zweiter Drehmessertyp” bezeichnet).

It is also possible that the operator sets the target speed itself in the automatic shift mode, wherein the set target speed represents the maximum value and the target speed is switched according to the load in several stages. For example, the operator himself can select whether the maximum value of the setpoint speed in the automatic shift mode is 3000 rpm, 4500 rpm or 6000 rpm. For example, when 3000 rpm is selected, for example, one of 1000 rpm, 2000 rpm and 3000 rpm is set automatically according to the load. On the other hand, when 4500 rpm is selected, for example, one of 1500 rpm, 3000 rpm and 4500 rpm is automatically set according to the load.

• (4) The number of types of speed modes is not limited to three types. There may also be two types or four or more species. With regard to the determination of the number of types of rotational speed modes, several possibilities are conceivable and, for example, a selective adjustment according to the types of rotary knives is possible. Thus, on the one hand, rotary cutters, which are better at cutting grass, etc., operate at a speed corresponding to the high-speed mode (for example, the in 9 shown nylon string cutter 51 , hereinafter also referred to as "first rotary type"), while in other rotary blades, even at a speed corresponding to the medium speed mode or the low speed mode, a sufficient work performance can be obtained (for example, with the circular blade, hereinafter also referred to as "second rotary dessert type").

In a grass cutter to which only the first rotary dessert type can be attached, or a grass cutter to which only the second rotary dessert type is attachable, good performance may possibly be obtained even with two types of speed modes. In a grass cutter to which selectively the first rotary type and the second rotary type are attached, it is not easy to obtain a sufficient work efficiency with a simultaneous low power consumption in both types of speed modes with both the first rotary type and the second rotary type.

For example, if there are two types of speed modes, each corresponding to a low speed mode and a medium speed mode, there is the possibility that the second turn dessert type works well, whereas the first turn type will not perform satisfactorily due to insufficient speed Working is possible. However, if, for example, two types of speed modes are provided, each of a low-speed mode and a high-speed mode can achieve a performance that is good with both the first rotary dessert type and the second rotary dessert type. In this case, however, when working using the second rotation type, work can not be performed at the rotational speed corresponding to the middle-speed mode and basically a suitable rotational speed, and instead, in a load range where a rotational speed is required In the mid-speed mode, work is always performed at a speed corresponding to the high-speed mode. Thus, although the work is actually feasible with a power consumption corresponding to the medium speed mode, the work is performed with a power consumption corresponding to the high speed mode, so there is the possibility of excessive power consumption.

Thus, in a grass cutter configured such that the first rotational type of dessert and the second rotational dessert type are selectively attachable, there are cases in which it is preferable that considering both a reduction in power consumption and a good performance, three or more types of Speed modes are set.

• (5) Die Erhöhungsbestimmungszeit A und die Erhöhungsbestimmungszeit B können den gleichen Wert oder unterschiedliche Werte aufweisen. Auch die Senkungsbestimmungszeit A und die Senkungsbestimmungszeit B können den gleichen Wert oder unterschiedliche Werte aufweisen.
• (6) Hinsichtlich des Messverfahrens der Drehzahl des Drehmessers 5 liegen keine besonderen Einschränkungen vor. So kann die Drehzahl des Drehmessers 5 beispielsweise direkt gemessen werden, oder die Drehzahl des Drehmessers 5 kann indirekt gemessen werden, indem die Drehzahl eines Aufbauelements, das die Drehung des Motors 31 auf das Drehmesser 5 überträgt (beispielsweise das Antriebszahnrad 42 oder das angetriebene Zahnrad 43) gemessen wird. Es kann auch ein so genannter sensorloser bürstenloser Motor verwendet werden, wobei die Drehzahl des Motors 31 ohne Sensoren elektrisch gemessen wird.
• (7) Wenn in der oben beschriebenen Ausführungsform der Betriebsmodus auf den automatischen Schaltmodus eingestellt ist, ist die Konfigurierung derart, dass stufenweise zwischen drei Arten von Drehzahlmodi umgeschaltet wird, doch kann auch ein direktes Umschalten aus dem Modus mit niedriger Drehzahl in den Modus mit hoher Drehzahl oder umgekehrt aus dem Modus mit hoher Drehzahl in den Modus mit niedriger Drehzahl, also ein überspringendes Umschalten, durchgeführt werden.

Therefore, the speed modes can also be selectively adjusted according to the types of rotary knives.

• (5) The increase determination time A and the increase determination time B may have the same value or different values. Also, the lowering determination time A and the lowering determination time B may have the same value or different values.
• (6) With regard to the measurement method of the rotational speed of the rotary knife 5 There are no special restrictions. So can the speed of the rotary knife 5 For example, be measured directly, or the speed of the rotary knife 5 can be measured indirectly by the speed of a bodywork element that controls the rotation of the engine 31 on the rotary knife 5 transmits (for example, the drive gear 42 or the driven gear 43 ) is measured. It is also possible to use a so-called sensorless brushless motor, the speed of the motor 31 is measured electrically without sensors.
• (7) In the above-described embodiment, when the operation mode is set to the automatic shift mode, the configuration is such that switching is progressively made between three types of speed modes, but also a direct shift from the low-speed mode to the high-level mode can be made Speed or vice versa from the high-speed mode to the low-speed mode, that is, a skip over, performed.

As a condition for directly switching from the low-speed mode to the high-speed mode, for example, a third increasing condition may be set. Specifically, as the boost current threshold, a boost current threshold C (for example, 10 ms) may be set, as the increase determination time, an increase determination time C (for example, 50 ms), and as the masking time, a masking time C (for example, 3000 ms).

• (8) Die vorstehende Ausführungsform wurde an dem Beispiel eines bürstenlosen Motors 31 veranschaulicht, doch kann es sich bei dem Motor 31 auch um eine andere Art von Motor als einen bürstenlosen Motor handeln. Auch hinsichtlich dessen, ob es sich um einen Wechselstrommotor oder um einen Gleichstrommotor handelt, liegen keine besonderen Einschränkungen vor. Bezüglich der Stromquelle ist der Akku 34 lediglich ein Beispiel, und es sind auch Konfigurierungen möglich, bei denen der Betrieb durch eine andere Stromquelle erfolgt. Beispielsweise ist eine Konfigurierungen möglich, wobei Netzwechselstrom (beispielsweise bei einer Netzwechselspannung von 100 V) eingespeist wird und der Betrieb mittels Netzstrom erfolgt.
• (9) Die vorliegende Erfindung ist nicht auf den in der vorstehenden Ausführungsform beschriebenen Grasschneider 1 beschränkt, sondern kann auf verschiedene Arten von Motorsensen angewandt werden.
• (10) Es ist möglich, eine Funktion, die in der vorstehenden Ausführungsform als Funktion eines einzelnen Aufbauelements beschrieben wurde, auf mehrere Aufbauelement zu verteilen, und Funktionen von mehreren Aufbauelementen können in einem Aufbauelement zusammengefasst werden. Wenigstens ein Teil der Elemente der vorstehenden Ausführungsform kann auch durch bekannte Elemente mit gleicher Funktion ersetzt werden. Auch kann ein Teil der Elemente der vorstehenden Ausführungsform wegfallen. Außerdem kann wenigstens ein Teil der Elemente der vorstehenden Ausführungsform andere Elemente der vorstehenden Ausführungsform ergänzen oder ersetzen. Darüber hinaus bilden verschiedene Aspekte, die im technischen Grundgedanken enthalten sind, welcher ausschließlich durch den Wortlaut der Ansprüche definiert ist, Ausführungsformen der vorliegenden Erfindung.

Also, for the condition for directly switching from the high-speed mode to the low-speed mode, for example, a third sinking condition may be set. Concretely, as the lowering current threshold value, a decreasing current threshold value C (for example, 4 A) and a lowering determination time C (for example, 50 ms) may be set as the lowering determination time.

• (8) The above embodiment was based on the example of a brushless motor 31 illustrated, but it may be in the engine 31 also to act a different kind of engine than a brushless motor. Also, whether it is an AC motor or a DC motor, there are no particular restrictions. Regarding the power source is the battery 34 merely an example, and configurations are also possible in which the operation is performed by another power source. For example, a configuration is possible, with AC mains power (for example, at an AC mains voltage of 100 V) is fed and the operation is done by means of mains power.
• (9) The present invention is not on the grass cutter described in the above embodiment 1 limited, but can be applied to various types of brushcutters.
• (10) It is possible to distribute a function described as a function of a single constituent element in the above embodiment to a plurality of constituent elements, and functions of plural constituent elements can be summarized in a constituent element. At least part of the elements of the above embodiment may also be replaced by known elements having the same function. Also, part of the elements of the above embodiment may be omitted. In addition, at least part of the elements of the above embodiment may supplement other elements of the above embodiment or replace. In addition, various aspects included in the basic technical concept, which is defined solely by the wording of the claims, form embodiments of the present invention.

Explanation of the reference numbers

• 1 Photos: Grass cutter, 2 Photos: Main tube, 3 : Control unit, 4 : Drive unit, 5 : Rotary knife, 6 : Cover, 7 : Carrying handle, 8th : Operating / display unit, 9 : Lock switch, 10 : Operating switch, 11 : Casing, 12 : Battery pack, 21 : On / off switch, 22 : Mode switch, 23 : Speed display section, 24 : State indicator light, 26 : Low speed indicator light, 27 : Indicator lamp for medium speed, 28 : High speed indicator light, 31 : Engine, 32 : Control section, 33 : Converter, 34 : Battery pack, 35 : Power supply circuit, 36 : Angle sensor, 37 : Current sense resistor, 38 : Amplifier, 41 : Rotary shaft, 42 : Drive gear, 43 : powered gear, 44 : Output shaft, 45 : Sensor board, 51 : Nylon string cutter, 52 : Kitchen sink, 53 : Nylon cord

SUMMARY

The object is to provide a brushcutter, wherein cutting work without excessive power consumption regardless of the load condition (state of the object to be cut) can be adequately performed. The object is achieved by switching a currently set speed mode, when an increase condition is met, to a speed mode with a higher set speed. The currently set speed mode is switched to a lower target speed speed mode when a droop condition is met. The increasing condition includes at least one condition based on a load applied to the engine, namely, the load applied to the engine reaches or exceeds an increase load threshold. Also, the lowering condition includes at least one condition based on a load applied to the engine, namely, that the load applied to the engine reaches or falls below a lowering load threshold.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• JP 2014-117267 [0002, 0003, 0004]

Claims (12)

Brushcutter, comprising: an operating rod, a rotary knife rotatably disposed at an end portion of the operating rod, an electric motor for driving the rotary knife, a rotation measuring section which measures a physical quantity indicative of the rotational speed of the rotary knife, a control section that sets a target value of the rotational speed to one of two or more target rotational speeds and controls the rotation of the electric motor based on the physical quantity measured by the rotational measuring section such that the rotational speed of the rotary blade is the set target rotational speed, and a load measuring section that measures the load applied to the electric motor, wherein an increase load threshold is set to switch the target speed to a higher target speed for the other target speed (s) other than the highest target speed of the two or more target speeds based on the load measured by the load measuring section; wherein a lowering load threshold is set which is to switch the target speed to a lower target speed for the other target speed (s) other than the lowest target speed of the two or more target speeds based on the load measured by the load measuring section, wherein the control section performs automatic setpoint switching processing, wherein, when the set load speed is set for the currently set target speed and the load measured by the load measuring section reaches or exceeds the increase load threshold, it is switched to a higher target speed than the currently set target speed and if currently set Set speed of the lowering load threshold value is set and the load measured by the load measuring section reaches or falls below the lowering load threshold, is switched to a lower target speed than the current target speed. The brushcutter of claim 1, wherein three or more desired speeds are provided. The brushcutter of claim 2, wherein an increase load threshold set for each of the three or more target speeds other than the highest target speed is set to be higher, the higher the target speed to be switched to, and a lowering load threshold is set for each of the three or more target speeds except the lowest target speed is set to a lower value, the lower the target speed to be switched to. Brushcutter according to claim 2 or 3, wherein three target speeds are provided, wherein the control section adjusts the target value of the rotational speed to one of the three target speeds in processing for automatic setpoint switching based on a load measured by the load measuring section. The brushcutter of any one of claims 1 to 4, wherein for the target speeds for which an increase load threshold is set, an increase time threshold is set that judges the duration for which the load reaches or exceeds the increase load threshold and for the target speeds for which a sink load threshold is set, a lowering time threshold value is set, which judges the duration for which the load reaches the lowering load threshold value or below, wherein the control section in the automatic setpoint switching processing, if set for the currently set target speed, the increase load threshold and the increase time threshold and the duration, for which the load measured by the load measuring section reaches or exceeds the increase load threshold, stops for the increase time threshold or longer, changes the currently set target speed to a higher target speed and if, for the currently set target speed, the sink load threshold and the sink time threshold are set and the duration for which the load measured by the load meter reaches or falls below the sink load threshold continues for the sink time threshold or longer, the currently set speed changes to a lower set speed. The brushcutter of claim 5, wherein the target speed for which the decrease time threshold is set is a decrease target set value, and the target speed to be switched from the decrease output set value based on the decrease time threshold and which is lower than the decrease output setpoint is a decrease target set value Lowering threshold is set longer than the increase time threshold, which is for the Reduction Target Setpoint is set and used when switching from this Reduction Target Setpoint to the Descent Output Setpoint. A brushcutter as claimed in any one of claims 1 to 6, wherein the target speed for which the subsidence load threshold is set is a subsidence target setpoint, and the target speed to be switched from the downsizing output setpoint based on the subsidence load threshold and which is lower than the downslope output setpoint is the target descent target and wherein the decreasing time threshold is set lower than the boost load threshold set for that decreasing target target value and used when switching from the decreasing target target value to the decreasing target target value. A brushcutter according to any one of claims 1 to 7, comprising a target speed notifying section which displays information indicating the set target speed. A brushcutter according to any one of claims 1 to 8, comprising a setpoint setting inputting section for accepting a setpoint speed setting input which sets a fixed speed mode as operating modes, the setpoint value of the rotation speed being set to a target speed set by the setpoint setting input section independently of the load measured by the loadmeasuring section, and an automatic shift mode in which automatic set point switching processing is performed, further comprising an operation mode setting input section for setting one of the fixed speed mode or the automatic shift mode, the control section setting the fixed speed mode as the operation mode by the operation mode setting input section; the electric motor rotates without performing the automatic setpoint switching processing such that the speed is controlled by the setpoint setting is set from the set target rotation speed, and when the automatic switching mode is set as the operation mode by the operation mode setting input section, the automatic set point switching processing is executed. The brushcutter of claim 9, comprising an operation mode notifying section that displays information indicating the set operation mode. The brushcutter of any one of claims 1 to 10 configured to selectively detachably attach a plurality of types of rotary blades, the plurality of rotary blades comprising at least one circular disc-shaped rotary blade configured with saw teeth on its outer periphery and a rotary blade comprising a cord-shaped member, wherein the cord-shaped member rotates due to the rotation of the electric motor in a tensioned state and the cutting object can be cut by the rotating cord-shaped element is applied to the cutting object. Brushcutter according to one of claims 1 to 11, which is configured such that a repeatedly rechargeable battery is releasably attachable thereto, wherein the electric motor can be supplied and operated by the battery when the battery is attached.

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