JP2011132838A - Single cylinder gas engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a single cylinder gas engine which sufficiently utilizes the engine ability by carrying out a preferable actuator control for restraining response delay and overshoot of rotation speed with respect to a target rotation speed change at load variation. <P>SOLUTION: The single cylinder gas engine 1 includes an engine body 2, control actuators 35, 53 for adjusting the amounts of a fuel gas and air supplied to the engine body 2, and a control device 9 for controlling the control actuators 35, 53 according to load variation. The control device 9 makes the control period TC for controlling the control actuators 35, 53 variable according to the rotation speed of the engine body 2 (average rotation speed N) and controls the control actuators 35, 53 at a frequency of 1 to 3 times per operation cycle (cycle period T) of the engine body 2. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a single-cylinder gas engine, and more particularly to improving the accuracy of tracking control for load fluctuations.

  In recent years, the development of distributed power supply devices aiming at energy saving and carbon dioxide emission reduction has been promoted, and the introduction in power consumption areas such as offices and apartment houses is increasing. One type of distributed power supply apparatus is a gas engine cogeneration apparatus that generates electric energy and heat energy using a gas engine using fuel gas as a drive source. In this type of apparatus, a single cylinder gas engine may be used for small output. And it is common to perform combustion control by controlling the amount of fuel gas and air supplied to the gas engine so as to follow the fluctuation of the electric load, and an example is disclosed in Patent Document 1. .

  The combustion control method for a gas engine disclosed in Patent Document 1 is a gas engine configured to introduce an air-fuel mixture obtained by mixing gas fuel and air into a combustion chamber from an air supply passage and perform ignition combustion. In addition to controlling the flow rate of the air-fuel mixture, the air supply pressure in the air supply passage is also controlled. As a result, the pressure loss of the air-fuel mixture in the air supply passage can be reduced, and air-fuel ratio control can be performed to maintain the excess air ratio properly when using gas fuel with variable calorific value, and stable engine output performance is demonstrated. It can be done.

JP-A-2005-240585

  By the way, according to the description of the embodiment of Patent Document 1, the controller automatically controls the flow rate of the air-fuel mixture and the supply pressure in the supply passage. As the controller, an electronic control device that normally has a built-in computer and operates by software is used. Not limited to Patent Document 1, a gas engine control device takes in information such as load fluctuations and engine rotation speed from other control devices and various sensors, performs internal computations, and performs a fuel valve, an air-fuel mixture throttle valve, and the like. In general, the control actuator is controlled. Normally, this control cycle is performed independently based on a fixed control cycle set inside the control device, regardless of whether the engine operation cycle is intake, compression, combustion, or exhaust. .

  Thus, if the control cycle of the control actuator and the engine operation cycle are independent of each other, there is a possibility that the two do not match and good control cannot be performed. For example, even if the condition of the air-fuel mixture is changed by controlling the control actuator, it is not immediately reflected in the rotational speed, but is reflected after the time when the air-fuel mixture is inhaled and ignited, resulting in a time lag. In addition, when the rotation speed is low, actuator control is performed multiple times during the operation cycle, but when the rotation speed increases, the number of actuator controls during the operation cycle decreases and the time lag becomes significant, or during the operation cycle There may be cases where actuator control is not performed.

If good control cannot be performed, when the target rotational speed changes due to load fluctuation, there is a possibility that the response of the rotational speed is delayed, or the target rotational speed is overshooted to increase or decrease. In particular, in a single-cylinder four-cycle gas engine, the ignition timing is only once every two rotations of the crankshaft, so the time lag is larger than in a two-cylinder or more engine, and the effect tends to be noticeable over a relatively long time. It is. Furthermore, in a gas engine used in a cogeneration system, it becomes difficult to maintain a good air-fuel ratio in response to fluctuations in electric load, and load following power generation may become unstable.

  The present invention has been made in view of the above-mentioned background, and performs an excellent actuator control capable of suppressing a response delay or an overshoot of the rotational speed with respect to a change in the target rotational speed at the time of a load change, and draws out the engine capacity, An object to be solved for a cogeneration system is to provide a single-cylinder gas engine that enables load-following power generation that is excellent in energy efficiency by maintaining a good air-fuel ratio at all times.

  The invention of a single cylinder gas engine according to claim 1 that solves the above-mentioned problem is an engine body, a control actuator that adjusts the amount of fuel gas and air supplied to the engine body, and the control cylinder according to load fluctuations. A single-cylinder gas engine having a control device for controlling an actuator, wherein the control device makes a control cycle for controlling the control actuator variable in accordance with a rotation speed of the engine main body, and operates the engine main body A cycle detection means for detecting a cycle is provided, and the control actuator is controlled at a frequency of 1 to 3 times for each operation cycle.

  According to a second aspect of the present invention, in the first aspect of the present invention, the apparatus includes a step determination unit that determines a step of the operation cycle, and the control device determines a control timing of the control actuator based on a determination result by the step determination unit. It is characterized by controlling.

  According to a third aspect of the present invention, in the method according to the second aspect, in the case where the step of the operation cycle can be determined by the step determination unit, the control device is configured to perform the predetermined time before the intake step determined by the step determination unit A control actuator is controlled.

  According to a fourth aspect of the present invention, in the second or third aspect, the process determining means includes a rotation detection pulley fixed to the crankshaft and having a plurality of teeth on an outer peripheral portion, and pulses from the plurality of teeth of the rotation detection pulley. A pulse generator that generates a signal, a pulse waveform shaping circuit that generates a pulse shaping waveform from the pulse signal, and an identification unit that identifies a compression process and an exhaust process from the pulse shaping waveform.

  According to a fifth aspect of the present invention, in the first aspect, the control device controls the control actuator at a frequency of 1.3 to 2.5 times for each operation cycle.

  The invention according to claim 6 is characterized in that, in any one of claims 1 to 5, a single-cylinder gas engine is used in a cogeneration system.

In the invention of the single-cylinder gas engine according to claim 1, the control device makes the control cycle variable according to the rotational speed, and controls the control actuator at a frequency of 1 to 3 times for each operation cycle of the engine body. For this reason, conditions such as the supply amount of air-fuel mixture obtained by mixing gas fuel and air and the air-fuel ratio can be controlled in each operation cycle and reflected in the nearest ignition timing. In other words, if the number of times of actuator control for one operation cycle is one or more times, the actuator can be reliably controlled one or more times before the ignition timing that can affect the engine speed. The actuator control result for the current engine speed affected by the ignition timing can be reflected in the engine speed at the next ignition timing. If the number of times of the control is 3 or less, excessive actuator control can be relatively suppressed with respect to the current engine speed affected by the previous ignition timing, so the engine rotation at the next ignition timing can be relatively suppressed. It is possible to suppress the speed from fluctuating excessively. On the other hand, if the number of times of the control is less than one, there is a case where the actuator cannot be controlled even once for the engine speed affected by the previous ignition timing. In response, the response may be delayed and fluctuations in the rotational speed (hunting) may not converge. If the number of times of the control is greater than 3, the actuator is controlled several times for one ignition timing, so the engine speed is excessively affected at the next ignition timing and the overshoot becomes large. May end up. Therefore, the control time lag can be limited to less than the cycle period of the operation cycle, and the engine performance can be extracted by suppressing the response delay of the rotation speed, overshoot, etc. with respect to the change in the target rotation speed when the load fluctuates.

  According to the second aspect of the present invention, the process discriminating means for discriminating the process of the operation cycle is provided, and the control timing of the control actuator is controlled based on the discrimination result by the process discriminating means. Therefore, the control actuator can be reliably controlled in each operation cycle.

  In the invention according to claim 3, the control device controls the control actuator a predetermined time before the intake process determined by the process determining means. Thereby, immediately after controlling the conditions such as the supply amount of the air-fuel mixture and the air-fuel ratio, the air-fuel mixture is sucked and ignited, so that the control time lag can be suppressed.

  In the invention according to claim 4, the process discrimination means includes a rotation detection pulley, a pulse generator, a pulse waveform shaping circuit, and an identification unit. Thereby, the process discriminating means can reliably discriminate each process of intake, compression, combustion, and exhaust, and the control device can obtain an optimal control timing and suppress a control time lag.

  In the invention according to claim 5, the control actuator is controlled at a frequency of 1.3 to 2.5 times for each operation cycle. Therefore, the actuator for control can be controlled in each operation cycle without discriminating each process, the control time lag can be limited to less than the cycle period of the operation cycle, and the response delay and overshoot of the rotation speed can be further suppressed. .

  In the invention which concerns on Claim 6, a single cylinder gas engine is used for a cogeneration apparatus. Accordingly, the generated power can be stabilized by suppressing the response delay of the rotation speed, overshoot, and the like. Further, it is possible to perform load following power generation with excellent energy efficiency by keeping the air-fuel ratio always good.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure explaining the whole structure of the cogeneration apparatus using the single cylinder gas engine of embodiment of this invention. FIG. 2 is a diagram for explaining a process discriminator in the embodiment of FIG. 1, where (1) is a structural diagram viewed from the direction of a white arrow A in FIG. FIG. 3 (3) is a diagram of a pulse shaping waveform obtained by shaping the pulse waveform. In the embodiment of FIG. 1, it is an operation | movement flowchart explaining the operation | movement which a control apparatus controls the actuator for control. It is a figure explaining the method of setting a control period based on a cycle period when the process in an operation cycle cannot be discriminated. It is a figure of the verification experiment result which checked the effect of the single cylinder gas engine of an embodiment. It is a figure of the verification experiment result which confirmed the effect of the single cylinder gas engine of an embodiment, and a control cycle differs from Drawing 5. It is a figure of the comparative experiment result which set the control period too small. It is a figure of the comparison experiment result which set the control period to excessive.

  An embodiment for carrying out the present invention will be described with reference to FIGS. FIG. 1 is a diagram illustrating the overall configuration of a cogeneration apparatus using a single cylinder gas engine 1 according to an embodiment of the present invention. In the illustrated configuration, the crankshaft 23 of the engine 1 is connected to the generator 101 to generate electric energy, and the cooling water of the engine 1 is circulated to the exhaust heat recovery device 102 so that the heat energy is effectively used. It has become. The single-cylinder gas engine 1 includes an engine body 2, a fuel gas supply unit 3, an air supply unit 4, an air-fuel mixture supply unit 5, an exhaust unit 6, a cooling water circulation unit 7, a process discriminator 8, a control device 9, and the like. Yes.

  The engine body 2 includes a single-cylinder cylinder 21 and a piston 22, and a crankshaft 23 that converts a reciprocating motion of the piston 22 into a rotational motion and outputs the rotational motion. An intake port 24, an exhaust port 25, and a spark plug 26 are provided at an upper portion of the cylinder 21, and a water jacket 27 is formed so as to surround the cylinder 21.

  The fuel gas supply unit 3 is a part corresponding to a fuel gas passage for supplying fuel gas from a gas supply source (not shown) to the mixer 51. The fuel gas supply unit 3 is provided with two solenoid valves 31, 32, a governor 33, and a fuel valve 34 in order from the gas supply source side. The fuel valve 34 has a fuel premixing actuator 35 that adjusts the supply amount of fuel gas by changing the opening degree AF. The air supply unit 4 is a part corresponding to an air passage that supplies air to the mixer 51. An air cleaner 41 is provided in the middle of the air supply unit 4. The air-fuel mixture supply unit 5 is a part that supplies the air-fuel mixture to the intake port 24 of the engine body 2. The air-fuel mixture supply unit 5 is provided with a mixer 51 that mixes fuel gas and air to create an air-fuel mixture, and a throttle valve 52 that adjusts the supply amount of the air-fuel mixture. The throttle valve 52 has a throttle actuator 53 that adjusts the supply amount of the air-fuel mixture by changing the opening degree AS.

  The fuel premixing actuator 35 of the fuel valve 34 and the throttle actuator 53 of the throttle valve 52 described above are control actuators, and are specifically controlled from the control device 9 using a stepping motor.

  The exhaust part 6 is a part corresponding to an exhaust gas passage through which exhaust gas is discharged from the exhaust port 25 of the engine body 2 to the outside. The exhaust unit 6 is provided with an exhaust heat exchanger 61 and an exhaust silencer 62 in order from the exhaust port 25 side. The cooling water circulation part 7 is a part corresponding to a cooling water passage for circulating the cooling water and cooling the engine body 2. The cooling water is circulated from the water jacket 27 of the engine body 2 to the water jacket 27 via the exhaust heat exchanger 61 and the exhaust heat recovery device 102. Thus, the cooling water receives thermal energy from the engine body 2, receives thermal energy from the exhaust gas by the exhaust heat exchanger 61, and releases thermal energy by the exhaust heat recovery device 102.

  The process discriminator 8 is a part corresponding to a part of the process discriminating means, and includes a rotation detection pulley 81 fixed to the crankshaft 23 and a pulse generator 85 that generates a pulse signal. 2A and 2B are diagrams for explaining the process discriminator 8. FIG. 2A is a structural diagram viewed from the direction of the white arrow A in FIG. 1, and FIG. 2B is a pulse waveform output from the pulse generator 85 to the control device 9. (3) is a diagram of a pulse shaping waveform obtained by shaping the pulse waveform. As shown in FIG. 2 (1), the rotation detection pulley 81 is a substantially disk-shaped member made of iron that is fixed to the crankshaft 23 and rotates together, and has three short teeth 82 and one long member on the outer periphery. Has teeth 83. Each tooth 82 and 83 is substantially rectangular, and its front edges 82a and 83a are equally spaced at a pitch of 90 °, and the length of the long teeth 83 in the circumferential direction is longer than that of the short teeth 82.

On the other hand, the pulse generator 85 is fixed to the outer surface of the engine body 2 so as to face the teeth 82 and 83 of the rotation detection pulley 81. The pulse generator 85 uses a magnetic field detection sensor that detects a change in the magnetic field due to the approach and separation of the magnetic material and outputs a pulse waveform. When the rotation detection pulley 81 rotates with the crankshaft 23 and the front edges 82a and 83a of the teeth 82 and 83 approach each other, the pulse generator 85 smoothly changes as shown in FIG. 2 (2). The positive voltage 86 is generated. The pulse generator 85 generates a negative voltage 87 of a mountain-shaped pulse when the trailing edges 82b and 83b of the teeth 82 and 83 approach each other. Regarding the pulse time defined between the start of the positive voltage 86 and the end of the negative voltage 87, the pulse time T83 of the long tooth 83 becomes longer than the pulse time T82 of the short tooth 82, and both can be distinguished. The long teeth 83 are arranged so as to be detected in the compression process and the exhaust process during the operation cycle.

  The control device 9 is a part that controls the operation of the engine 1. The control device 9 controls the fuel premixing actuator 35 and the throttle actuator 53, adjusts the opening degree AF of the fuel valve 34 and the opening degree AS of the throttle valve 52, and controls the ignition timing of the spark plug 26. Further, the control device 9 also functions as a pulse waveform shaping circuit and an identification unit in the process discrimination means, and performs the processing of the pulse waveform of the process discriminator 8.

  To describe in detail the function of the control device 9 as the process discriminating means, first, the pulse times T82 and T83 in the pulse waveform of FIG. 2 (2) are shaped into unipolar rectangular pulse shaping waveforms T82A and T83A. The pulse shaping waveform of FIG. 2 (3) is generated.

  As is well known, in a four-stroke engine, the crankshaft 23 rotates twice during one operation cycle. For this reason, six short pulse-shaped waveforms T82A and two long pulse-shaped waveforms T83A are generated in one operation cycle, and a combination of two consecutive pulse-shaped waveforms out of a total of eight pulse-shaped waveforms. Are assigned to one of the processes of compression, combustion, exhaust, and intake. The long pulse shaping waveform T83A is assigned to the compression process and the exhaust process. Specifically, as shown in FIG. 2 (3), one long pulse shaping waveform T83A and the preceding short pulse shaping waveform T82A are assigned to the compression process. The other long pulse shaping waveform T83A and the preceding short pulse shaping waveform T82A are assigned to the exhaust process. Two short pulse shaping waveforms T82A after the compression process are assigned to the combustion process. Two short pulse shaping waveforms T82A after the exhaust process are assigned to the intake process.

  In the compression process, since the air-fuel mixture in the cylinder 21 is compressed by the piston 22, the rotation speed of the crankshaft 23 is slowed down. On the other hand, since the exhaust port 25 is open in the exhaust process, the exhaust gas is not compressed, and the rotation speed of the crankshaft 23 is faster than that in the compression process. Therefore, the control device 9 measures the time difference between the rising edge of the long pulse shaping waveform T83A and the rising edge of the next short pulse shaping waveform T82A, determines that the process including the long time difference TL is the compression process, and includes the short time difference TS. The process is identified as an exhaust process. Therefore, the compression process and the exhaust process can be distinguished by comparing the time differences TL and TS.

  In addition to the above-described process determination, the control device 9 calculates the cycle period T required for one operation cycle from the eight pulse-shaped waveforms, further calculates the reciprocal thereof and doubles it to calculate the average rotational speed N. . Therefore, in the present embodiment, the process determination unit also functions as a cycle detection unit that detects an operation cycle.

Next, the operation in which the control device 9 controls the fuel premixing actuator 35 and the throttle actuator 53 will be described with reference to FIG. FIG. 3 is an operation flow diagram illustrating an operation in which the control device 9 controls the control actuator. As shown in the figure, the control device 9 performs the above-described process determination process in step S1, and calculates the cycle period T and the average rotation speed N of the operation cycle in step S2. Next, in step S3, it is determined whether or not the process determination process is completed. If completed, the process proceeds to step S4, and if not completed, the process proceeds to step S5. Whether or not the process discriminating process is completed is determined by measuring the time difference between the rising edge of the long pulse shaping waveform T83A and the rising edge of the next short pulse shaping waveform T82A in the process discriminating process. Judge by no. That is, the determination is made based on whether or not the compression process and the exhaust process can be distinguished.

  In step S4, the control timing is set a predetermined time ΔT before the start of the intake process in the determined process. The predetermined time ΔT is a time when the fuel premixing actuator 35 and the throttle actuator 53 respond to the control command, and the fuel valve 34 is opened and the opening degree AF and the opening degree AS of the throttle valve 52 are changed. This can be determined in consideration of the supply delay time until the air-fuel mixture in which the supply amount or the air-fuel ratio has changed is supplied into the cylinder 21 of the engine body 2. The supply delay time can be determined in consideration of the average rotation speed N. By appropriately setting the predetermined time ΔT, the air-fuel mixture under new conditions is drawn immediately after the control, and the control time lag can be suppressed. The predetermined time ΔT can be obtained by calculation, but may be obtained experimentally. In practice, the predetermined time ΔT is obtained in advance and stored in the control device 9 as a map in the form of a list. The map in the list form stores the relationship of the predetermined time ΔT with respect to the average rotational speed N and the like.

  In step S5, since the process cannot be determined, it is difficult to set the control timing based on the predetermined time ΔT. Therefore, a control cycle TC is set for each cycle cycle T calculated in step S2. Specifically, the control cycle TC shown in FIG. 4 is set. FIG. 4 is a diagram for explaining a method for setting the control period TC based on the cycle period T when the process in the operation cycle cannot be determined. The horizontal axis in the figure is the average rotational speed N, and the vertical axis is the period or time. Graph (1) in the figure shows the cycle period T of the operation cycle, and broken line graph (2) shows half of the cycle period T, that is, the rotation period TK of the crankshaft 23 (this is also the reciprocal of the average rotation speed N). The graph (3) shows the control cycle TC.

  The range between the lower rotational speed Nmin and the upper rotational speed Nmax in the figure is the normal range of the single cylinder gas engine 1. Further, the normal range is divided into a low rotation range from the lower rotation speed Nmin to the intermediate rotation speed Nmid and a high rotation range from the intermediate rotation speed Nmid to the upper rotation speed Nmax. No is the minimum rotation speed, and appears temporarily when the engine is started. A predetermined rotational speed Na is set between the minimum rotational speed No and the lower rotational speed Nmin.

  In this embodiment, the average rotational speed N is divided into three regions, and a constant control cycle TC is set in each region. That is, the average rotational speed N is set to a first region having an intermediate rotational speed Nmid or higher, a second region between the predetermined rotational speed Na and the intermediate rotational speed Nmid, and a third region between the predetermined rotational speed Na and the minimum rotational speed No. A constant control cycle TC is set for each region. Specifically, the control cycle TC at the lowest average rotation speed N in each region is set as a fixed control cycle. That is, in the first region, the control cycle TC at the intermediate rotational speed Nmid is set to the first fixed control cycle TC1, and in the second region, the control cycle TC at the predetermined rotational speed Na is set to the second fixed control cycle TC2, and the third In the region, the control cycle TC at the minimum rotational speed No is set to the third fixed control cycle TC3.

The control device 9 holds a plurality of fixed first fixed control periods TC1, second fixed control periods TC2, and third fixed control periods TC3, and can control the control actuator almost twice every operation cycle. As described above, the control cycle TC = first fixed control cycle TC1 is selected in the first region including the high rotation region, and the control cycle TC = second fixed control cycle TC2 is selected in the second region including the low rotation region. In three areas, control cycle TC = third fixed control cycle TC3 is selected. The control cycle TC shown in FIG. 4 is the same as or slightly larger than the rotation cycle TK. Therefore, the actuator control is performed at a frequency close to once during the rotation cycle, in other words,
The frequency becomes less than twice and close to twice every operation cycle.

  Returning to step S6 of FIG. 3, it is determined whether the current time is the control timing. The determination is made at the control timing set in step S4 or the control timing based on the control cycle TC set in step S5. If it is the control timing, a control command is determined based on a predetermined internal calculation in step S7, the fuel premixing actuator 35 and the throttle actuator 53 are controlled, and the opening degree AF of the fuel valve 34 and the opening degree AS of the throttle valve 52 are set. adjust.

  Next, the effect of the single cylinder gas engine 1 of the above-described embodiment will be described with reference to FIGS. FIG. 5 is a diagram of a verification experiment result confirming the effect of the single cylinder gas engine 1 of the embodiment, and the control cycle TC is set to the first fixed control cycle TC1 in the normal range. FIG. 6 is also a diagram of the verification experiment result, in which the control cycle TC is set to the second fixed control cycle TC2 in the normal range. FIG. 7 is a diagram of a comparative experiment result in which the control cycle TC is set too small, and FIG. 8 is a diagram of a comparison experiment result in which the control cycle TC is set too large.

  5 to 8, the horizontal axis represents time t, and the vertical axis represents the average rotational speed N, the opening degree AF of the fuel valve 34, and the opening degree AS of the throttle valve 52. In each experiment, the target rotational speed is changed stepwise, and the control device 9 performs follow-up control based on the control cycle TC on the assumption that the operation cycle process cannot be detected, and measures the three quantities N, AF, and AS. did. Specifically, the target rotational speed is increased from the lower rotational speed Nmin to the intermediate rotational speed Nmid and the intermediate high speed rotational speed Nmm to the upper rotational speed Nmax, and then the upper rotational speed Nmax to the middle high rotational speed Nmm, intermediate rotational speed. Through Nmid, the rotation speed was decreased to the lower rotation speed Nmin.

  In FIG. 5, the control cycle TC = the first fixed control cycle TC1, and the condition is that the control is performed at the intermediate rotational speed Nmid at a frequency of just twice for each operation cycle. In this case, the condition is that the control is performed at a frequency of 2.31 times per operation cycle (corresponding to point M1 in FIG. 4) at the lower rotation speed Nmin, and 1.71 times per operation cycle of the upper rotation speed Nmax. This is a condition for performing control at a frequency (corresponding to point M2 in FIG. 4). Further, the control cycle TC in FIG. 6 is equal to the second fixed control cycle TC2, and the control is performed at a frequency of 1.85 times (corresponding to the point M3 in FIG. 4) for each operation cycle at the lower rotational speed Nmin. The condition is that the control is performed at a frequency of 1.37 times (corresponding to the point M4 in FIG. 4) for each upper rotation speed Nmax operation cycle. On the other hand, the control period TC = TC1 × 0.25 in FIG. This is a condition for performing control at a frequency of 6.84 to 9.24 times per operation cycle in the normal range. Further, the control cycle TC in FIG. 8 is set excessively as TC1 × 2.5. This is a condition in which control is performed at a frequency of 0.68 to 0.92 times for each operation cycle in the normal range.

The responsiveness of the average rotation speed N shown in FIG. 5 is better than those in FIGS. However, as shown by P1 in the figure, some instability is observed at the lower rotational speed Nmin.
The responsiveness of the average rotational speed N shown in FIG. 6 is generally good in the entire range of the normal range.

  On the other hand, in FIG. 7, the average rotational speed N overshoots immediately after the target rotational speed increases as indicated by P2 in the figure, and the average rotational speed immediately after the target rotational speed decreases as indicated by P3 in the figure. N undershoots. Further, as indicated by P4 in the figure, the hunting of the average rotational speed N does not converge at the lower rotational speed Nmin. That is, if the control cycle TC is set too small, the response of the average rotational speed N is lowered due to reasons such as inconsistency with the reaction delay time of the control actuator.

In FIG. 8, as indicated by P <b> 5 in the figure, immediately after the target rotational speed increases, it takes time until the average rotational speed N decreases and settles after once overshooting. Further, as indicated by P6 in the figure, it takes time until the average rotational speed N settles immediately after the target rotational speed decreases. That is, when the control cycle TC is set excessively, the response delay of the average rotation speed N becomes significant.

  As is clear from comparison with FIGS. 7 and 8, the responsiveness of the average rotational speed N in FIGS. 5 and 6 is good, and the effect is clear. As shown in FIG. 5 and FIG. 6, the control cycle TC may be constant within the normal range of the average rotation speed N. At that time, it is necessary that the number of times of control of the control actuator for each operation cycle is within the range of 1 to 3 in the normal range of the average rotation speed N. The number of times of control is preferably 1.3 to 2.5. Note that 1.4 or 1.5 can be selected as a preferable lower limit value of the number of times of control per operation cycle. As a preferable upper limit value of the number of times of control per one operation cycle, 2.3 or 2.4 can be selected. Also, as shown in FIG. 4, the average rotational speed is divided into a plurality of regions (in FIG. 4, it is divided into three regions, but it may be divided into two regions or four or more regions). A control cycle may be set for each region. Alternatively, the control cycle may be changed according to the average rotation speed. For example, control cycle TC = rotation cycle TK. In any case, it is necessary to satisfy the condition that the number of times of control of the control actuator per operation cycle is 1 to 3 times (preferably 1.3 to 2.5 times).

  In the single-cylinder gas engine 1 of the embodiment, the control device 9 makes the control cycle TC variable according to the average rotational speed N, and the fuel premixing actuator 35 and the throttle actuator 53 are moved at a frequency close to twice for each operation cycle. By controlling, the opening degree AF of the fuel valve 34 and the opening degree AS of the throttle valve 52 are adjusted. Thereby, the time lag of control can be shortened. Therefore, it is possible to extract the capacity of the engine 1 by suppressing a delay in response of the average rotational speed N, overshoot, and the like with respect to load fluctuation.

  Furthermore, when the single-cylinder gas engine 1 of the embodiment is used in a cogeneration system, the generated power can be stabilized. Further, it is possible to perform load following power generation with excellent energy efficiency by keeping the air-fuel ratio always good.

  In the above embodiment, the process discriminating means including the process discriminator 8 shown in FIG. 2 is used as the cycle detecting means for detecting the operation cycle, but the present invention is not limited to this. For example, a sensor that simply detects one rotation of the crankshaft may be provided, and the rotation speed and the cycle period of the operation cycle may be obtained. Alternatively, the ignition timing may be detected to obtain the rotation speed and the cycle period of the operation cycle. Further, the setting of the control cycle TC is not limited to the embodiment of FIG. 4, and various setting methods can be used. Further, as is apparent from the results of FIGS. 5 and 6, the method of controlling the control timing by setting the control cycle TC is the rotational speed even without the control of setting the control timing a predetermined time before the intake step. Response delay and overshoot can be satisfactorily suppressed. Therefore, control without step S3 and step S4 in FIG. 3 is also possible.

1: Single cylinder gas engine 2: Engine body 21: Cylinder 22: Piston 23: Crankshaft 24: Intake port 25: Exhaust port 26: Spark plug 27: Water jacket 3: Fuel gas supply unit 34: Fuel valve 35: Fuel reserve Mixing actuator 4: Air supply unit 5: Mixture supply unit 51: Mixer 52: Throttle valve 53: Throttle actuator 6: Exhaust unit 7: Cooling water circulation unit 8: Process discriminator 81: Rotation detection pulley 82: Short teeth 83: Long Teeth 85: Pulse generator 9: Control device 101: Generator 102: Waste heat recovery device T: Cycle period TK: Rotation period TC: Control period TC1, TC2, TC3: First, second, and third fixed control periods N: Average rotational speed Nmin: Lower rotational speed Nmid: Intermediate rotational speed Nmax: Upper rotational speed

Claims (6)

A single-cylinder gas engine comprising an engine body, a control actuator that adjusts the amount of fuel gas and air supplied to the engine body, and a control device that controls the control actuator according to load fluctuations,
The control device includes a cycle detection means for making a control cycle for controlling the control actuator variable according to a rotation speed of the engine body, and detecting an operation cycle of the engine body. A single-cylinder gas engine that controls the control actuator three times.   2. The apparatus according to claim 1, further comprising: a process determining unit that determines a process of the operation cycle, wherein the control device controls a control timing of the control actuator based on a determination result by the process determining unit. Cylinder gas engine.   3. The control device according to claim 2, wherein when the step of the operation cycle can be determined by the step determination unit, the control device controls the control actuator a predetermined time before the intake step determined by the step determination unit. Characteristic single cylinder gas engine.   4. The process determining means according to claim 2, wherein the process determining means includes a rotation detection pulley fixed to the crankshaft and having a plurality of teeth on an outer peripheral portion, and a pulse generator for generating a pulse signal from the plurality of teeth of the rotation detection pulley. A single cylinder gas engine comprising: a pulse waveform shaping circuit that generates a pulse shaping waveform from the pulse signal; and an identification unit that identifies a compression process and an exhaust process from the pulse shaping waveform.   2. The single cylinder gas engine according to claim 1, wherein the control device controls the control actuator at a frequency of 1.3 to 2.5 times for each operation cycle.   The single-cylinder gas engine according to any one of claims 1 to 5, wherein the single-cylinder gas engine is used in a cogeneration system.

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