JPH02286874A - Start characteristic enhancing device for reciprocation engine - Google Patents

Abstract

PURPOSE:To enhance the engine starting characteristic by operating a motor under appropriate control so that the piston of a certain cylinder of engine takes the position of suction upper dead point while a sensing signal from a crank angle sensing means is used as feedback signal at the time of the engine being at a standstill. CONSTITUTION:When it is judged that the engine concerned is at a standstill, the crank angle thetac of a certain cylinder #1 is read by the use of a signal from a crank angle sensor 5, while the crank angle thetac' until the piston 10 of the cylinder #1 gets to the suction upper dead point is calculated by ECU 6, and the result therefrom is used as a feedback signal to drive a motor 4. In the condition where the piston 10 of the cylinder #1 has attained the position of suction upper dead point, the motor 4 is stopped, and the next start is awaited. When an engine key is turned on, the start fuel is fed to the cylinder #1, and ignition is made quickly 180 deg. after engine revolution since the key was turned on. Now the process intrudes into the combustion stroke, followed by combustion strokes of cylinder #3, 4, 2 one after another, to lead to starting of the engine.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a device for improving the startability of a reciprocating engine installed in an automobile or the like.

[Prior Art] Conventionally, automobiles and the like have been equipped with, for example, a multi-point type multi-cylinder reciprocating engine.When starting such a reciprocating engine, fuel is supplied while starting a starter motor attached to the engine. The fuel is injected from an injector (electromagnetic fuel injection valve), and a spark plug is ignited at the required timing.

[Problems to be Solved by the Invention] By the way, with the conventional means as described above, it is not possible to determine at what position the crank phase of the engine is stopped at the time of starting, so it is difficult to operate all injectors at the same time, especially when starting at a low temperature. However, even in this case, the engine will not start immediately, and the ignition will fail twice at worst until the cylinder identification signal is received.

In other words, regarding starting a conventional 4-cylinder reciprocating engine,
To explain using FIG. 6, firstly, the first to fourth cylinders #1
．． #2. #3. Even if fuel is injected simultaneously from each injector into all cylinders in #4 (see the hatched part in Figure 6), for example, if a specific cylinder is designated as the first cylinder, the piston in cylinder #1 will not always be injected. It is not necessarily at the intake top dead center position. Therefore, ignition may occur after the engine has rotated two revolutions (one cycle) or more.

For this reason, engine startability is poor, and the air-fuel ratio (A/F)
The cylinder Stl, #3 becomes too rich, while the cylinders #2, 34 become lean, which increases the amount of unburned HC (hydrocarbons) discharged, and increases the amount of fuel at startup. There is a problem with inviting people.

The present invention was developed in view of these problems, and improves the startability of the engine by controlling the piston in a specific cylinder to be at the intake top dead center position when the engine is stopped. Improves and unburned HC
An object of the present invention is to provide a device for improving startability of a reciprocating engine, which is capable of reducing the startability of a reciprocating engine.

[Means for Solving the Problems] In order to achieve the above object, the reciprocating engine startability improving device of the present invention includes a motor capable of rotationally driving a crankshaft of a reciprocating engine and a crank angle of the engine. a crank angle detection means, and immediately moves the motor so that the piston in a specific cylinder of the engine is at the intake top dead center position while using the detection signal from the crank angle detection means as a feedback signal when the engine is stopped. It is characterized by being provided with a control means.

[Function] In the reciprocating engine startability improving device of the present invention described above, when the engine is stopped, the motor control means receives a signal from the engine crank angle detection means as a feedback signal. Then, with this motor control means,
Generate a control signal based on this feedback signal,
This is supplied to the motor. As a result, the motor is immediately operated so that the piston of the specific cylinder is at the intake top dead center position.

[Example] A device for improving startability of a reciprocating engine as an example of the present invention will be explained below with reference to the drawings. Fig. 1 is a schematic configuration diagram of an engine system having this device, and Fig. 2 is a diagram showing a schematic configuration of an engine system having this device. A front view schematically showing the internal mechanism of the engine, FIG. 3 is a flowchart showing the control operation when the engine is stopped, FIG. 4 is a flowchart showing the control operation when the engine is started, and FIG. 5 is a flowchart showing the control operation when the engine is started. FIG.

First, in Figure 1, 1 is a reciprocating engine.

2 is a transmission, 3 is a fan, and the reciprocating engine 1 is provided with a motor (for example, an alternator/starter; cell dyna) 4 in series or parallel with a crankshaft 7 (see Fig. 2); A motor control signal generated based on a detection signal from a crank angle sensor (crank angle detection means) 5 that detects the crank angle is supplied from an electronic control unit (ECU) 6 to the motor control unit 6. That is, while the engine is stopped, the ECU 6 detects the crank angle for a specific cylinder #1 using the crank angle sensor 5, and uses the detection signal as a feedback signal to ensure that the piston 1o in the specific cylinder #1 is at the intake top dead center. It has a function as a motor control means for driving and controlling the motor 4 until the motor 4 reaches the position.

The motor 4 is connected to a crankshaft 7 as shown in FIG.
It is removably connected to a ring gear provided on the outer periphery of a flywheel 8, so that when the motor 4 is rotationally driven, the ring gear, flywheel 8, and crankshaft 7 can be rotationally driven. The piston 10 in specific cylinder #1 can be moved to the intake top dead center position.

Further, in FIG. 2, 9 represents a connecting rod, 11 represents an exhaust valve, and 12 represents an intake valve.

Next, the operation of this embodiment will be explained using the flowcharts shown in FIGS. 3 and 4. First, when the engine is stopped, as shown in FIG. 3, it is determined in step a1 that the engine is stopped. and.

In step a2, the crank angle Oc of the specific cylinder #1 is read using the signal from the crank angle sensor 5, and in step a3, the crank angle Oc of the specific cylinder #1 is read until the piston 10 of the cylinder #1 reaches the intake top dead center (TDC). The crank angle θC' is calculated by the ECU 6 and is used as a feedback signal to drive the motor 4 (step a4).

Thereafter, with the piston 10 of the specific cylinder #1 at the intake top dead center position, the rotation of the motor 4 is stopped to wait for the next start.

When starting the engine, first turn on the engine key in step b1, as shown in Fig. 4.
In step b2, starting fuel is supplied to cylinder #1, and in step b3.

The starter is energized and then ignited.

The main injection routine is executed (see step b4). This starts the engine.

Next, the operation at the time of starting the engine will be explained using the time chart shown in FIG. rotation 18
After 0° (this rotation angle is smaller than the conventional one),
Ignition is promptly performed, and this specific cylinder #1 enters the explosion stroke.

Below, continue with cylinder #3. #4. #28 is also sequentially supplied with fuel and ignited, so that cylinder #3. #4. #2 also enters the explosion stroke one after another, leading to the engine starting.

As described above, by using this device, the engine can be started quickly, so the amount of fuel supplied at the time of engine startup can be reduced, and the emission of unburned HC can also be reduced, which makes it possible to start the engine quickly. This greatly improves the startability of the engine.

Note that instead of using the alternator/starter (cell dyna) as the motor for this device as in the above embodiment, a dedicated motor may be used for this device.

Furthermore, it goes without saying that the specific cylinder is not limited to the first cylinder.

[Effects of the Invention] As detailed above, according to the reciprocating engine startability improving device of the present invention, when the engine is stopped, the detection signal from the crank angle detection means of a specific cylinder is fed back, and the crank angle of the engine is adjusted. By rotating the shaft with a motor so that the piston of the specific cylinder is at the intake top dead center position, the engine starts quickly from the specific cylinder, which reduces the amount of fuel used when starting the engine. This has the advantage that it can also reduce the generation and emissions of unburned HC.

[BRIEF DESCRIPTION OF THE DRAWINGS] Figures 1 to 5 show a device for improving startability of a reciprocating engine as an embodiment of the present invention. The figure is a front view schematically showing the internal mechanism of an engine equipped with this device.
FIG. 4 is a flowchart showing the control operation when the engine is stopped, FIG. 4 is a flowchart showing the control operation when the engine is started, FIG. 5 is a time chart showing the operation of this embodiment, and FIG. It is a time chart of a corresponding conventional example. 1- Reciprocating engine, 2- Transmission, 3-
EC with functions of fan, 4-motor, 5-crank angle sensor (crank angle detection means), 6-motor control means
U, 7-crankshaft, 8--flywheel, 9-connecting rod, 10-piston, 11-exhaust valve,
12.-Intake valve.

Claims (1)

[Claims] The engine is equipped with a motor capable of rotationally driving a crankshaft of a reciprocating engine, and a crank angle detecting means for detecting the crank angle of the engine, and when the engine is stopped, a detection signal from the crank angle detecting means is used as a feedback signal. 1. An apparatus for improving startability of a reciprocating engine, comprising a motor control means for driving the motor so that a piston in a specific cylinder is at an intake top dead center position.