JP3187866B2 - Control device for two-stroke engine with crankcase compression - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a crankcase compression type two-cycle engine which controls ignition timing and the like based on an engine speed and an engine load. About improvement.

[0002]

2. Description of the Related Art Conventionally, when controlling an engine operation amount such as an ignition timing, an exhaust start timing, and a fuel amount, an engine load and an acceleration state in addition to an engine speed are obtained, and optimal control in accordance with these is performed. I have to. For example, as for the ignition timing, the reference ignition timing obtained from the engine speed is retarded when the engine load is large, and advanced when the engine load is small. Conventionally, as a method for obtaining the engine load and the acceleration state, for example, a throttle opening, a throttle opening speed, an engine rotation rate, an exhaust temperature, and the like are detected, and the engine load and the acceleration state are calculated based on these. I have.

[0003]

However, in the case of the above-mentioned method of obtaining the engine load from the throttle opening, the design change around the carburetor and the throttle is required to mount the throttle position sensor, and the structure becomes more complicated.
In addition, there is a problem that the throttle operation becomes heavier by the provision of the sensor. Further, in the case of the method of obtaining the engine load from the rate of increase of the engine speed, the method can be used for control in an accelerated state but cannot be used for control in a steady operation state.
Further, the method using the exhaust gas temperature has a problem that accuracy is low and response delay is large.

The present invention has been made in view of the above-mentioned conventional problems, and has a simple structure, does not affect the throttle operation, and can be used regardless of the driving condition.
It is another object of the present invention to provide a control device for a crankcase compression type two-cycle engine with high control accuracy and responsiveness.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a crankcase compression system which controls an engine operation amount such as an ignition timing, an exhaust start timing, and a fuel amount in accordance with an engine speed, an engine load, and an acceleration state. In a control device for a two-cycle engine, a pressure sensor that detects a crankcase pressure in a crankcase or a scavenging passage, an engine control reference signal is obtained based on an engine speed, and a peak value of a pressure detected by the pressure sensor is determined. When the increase value with respect to the peak value in the previous cycle is larger than the peak value and smaller than a predetermined increase value, the engine control reference signal is output. When the increase value is larger, the first correction value obtained by correcting the engine control reference signal is output. Output, the peak value is smaller than the predetermined peak value, and the rise value with respect to the peak value of the previous cycle is smaller than the predetermined rise value. While outputting a second correction value obtained by correcting the engine control reference signal is, when a large is characterized by comprising a control unit for outputting a third correction value obtained by correcting the engine reference signal.

[0006]

FIG. 2 shows that the throttle opening is fully open, 1/2
FIG. 4 is a characteristic diagram showing the relationship between the engine speed and the peak pressure in the crankcase when the engine is open and 1/4 open. From this figure, it can be seen that the throttle opening, that is, the higher the load, the higher the crankcase peak at any engine speed. It can be seen that the pressure has also increased. Therefore, it can be seen that the engine load can be determined by detecting the peak pressure in the crank chamber instead of detecting the throttle opening. According to the control apparatus for a two-cycle engine according to the present invention, the engine control is performed based on the engine speed. When the reference value is obtained, the engine control reference signal is output when the peak value of the crankcase pressure is larger than the predetermined peak value, and when the increase value with respect to the peak value of the previous cycle is smaller than the predetermined increase value, A first correction value obtained by correcting the engine control reference signal is output. When the peak value of the crankcase pressure is smaller than the predetermined peak value, and when the increase value with respect to the peak value of the previous cycle is smaller than the predetermined increase value, the second correction value obtained by correcting the engine control reference signal is output. In this case, since the third correction value obtained by correcting the engine reference signal is output, the structure is simpler than that of the conventional device provided with a throttle position sensor because the structure around the throttle is not required, and Has no effect on throttle operation. Further, since the crank chamber pressure can be detected for each cycle of the engine, the response to a load change is extremely high, and the control accuracy is also high. Furthermore, it can be used regardless of the operating state of the engine.

[0007]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 to 3 are views for explaining a control device of a two-stroke engine according to an embodiment of the present invention.
FIG. 2 is a configuration diagram, FIG. 2 is a characteristic diagram showing a relationship between an engine speed and a crank chamber peak pressure for each throttle opening, and FIG. 3 is a flowchart for explaining operation.

In FIG. 1, reference numeral 1 denotes a device equipped with the apparatus of this embodiment.
The engine 1 is a crankcase compression type engine in which a cylinder body 3 and a cylinder head 4 are stacked and fastened on the front upper surface of a crankcase 2.

A crankshaft 2 is provided in the crankcase 2.
The crank chamber for accommodating a is formed, and this crank chamber communicates with the upper part of the cylinder bore through a scavenging passage formed in the cylinder body 3. An intake port 2 communicating with the crank chamber is provided on the back of the crankcase 2.
b is formed. An intake manifold 6 is connected to the intake port 2a via a reed valve 5, and a fuel injection valve 7 and a throttle valve 8 are arranged in the intake manifold 6. The fuel injection valve 7 is connected to a fuel control device 9 for controlling the fuel injection amount and the injection timing by the injection valve 7.

An exhaust pipe 10 is connected to an external connection port of the exhaust port of the cylinder body 3, and an exhaust control valve 11 is rotatably disposed at the external connection port. The exhaust control valve 11 is connected to an exhaust control device 12 that controls the rotation angle of the exhaust control valve 11 to control the exhaust start timing. An ignition plug 13 is screwed into the cylinder head 4, and an ignition control device 14 for controlling ignition timing is connected to the ignition plug 13.

A pressure sensor 15 for detecting the pressure of the mixture in the crank chamber is connected to the scavenging passage.
Further, a rotation sensor 16 for detecting the engine speed is connected to the crankshaft 2a. The pressure signal a and the rotation speed signal b from the two sensors 15 and 16 are input to the engine control unit 17.

The engine control unit 17
Extracts the pressure peak value for each cycle from the pressure signal a, obtains the engine load from the peak value, and calculates the acceleration state of the vehicle from the change in the peak value. The engine control unit 17 determines the ignition timing based on the reference ignition timing obtained from the engine rotation speed, on the retard side when the engine load is large, on the advanced side when the engine load is small, and on the advanced side when the engine load is accelerated. An ignition timing correction signal A for correcting the ignition angle to the advance side
And the exhaust start timing is the reference exhaust start timing calculated from the engine speed.If the engine load is large, it is advanced, if it is small, it is retarded, and if it is accelerated, it is advanced. And outputs an exhaust start timing correction signal B to the exhaust control device 12. Further, when the engine control device 17 determines that the vehicle is accelerating, it outputs a fuel correction signal C for increasing the reference fuel injection amount obtained from the engine speed to the fuel control device 9.

Next, the operation and effect of this embodiment will be described. First, the operation of the apparatus of this embodiment will be described with reference to FIG. When the control program starts, the engine control unit 17 reads the pressure signal a from the pressure sensor 15 and the rotation speed signal b from the rotation sensor 16 (step S1), and based on the engine rotation speed, the ignition timing and the exhaust start timing. , A reference value of the fuel injection amount is set (step S2). Next, it is determined whether or not the crankcase peak pressure is higher than 300 mmHg (step S3). If it is higher, it is determined in step S4 whether or not the increase value with respect to the peak pressure in the previous cycle is higher than 30 mmHg. If the increase value is small, the reference value is output as it is (step S
5) If it is larger, it is determined that the vehicle is in an acceleration state, and
Output the first correction value obtained by correcting each of the two reference values (
Steps S6 and S7).

If the peak pressure is small in step S3, it is determined that the load is a partial load (partial), and the ignition timing is advanced, and the exhaust start timing is set to a delayed second correction value. (Step S
8) In addition, the rise value with respect to the peak pressure in the previous cycle is
It is determined whether it is greater than 30 mmHg, and if it is smaller, the second correction value is output as it is (steps S9, S1).
0). Further, if the increase value is large in the step S9, it is determined that the vehicle is in the partial load and acceleration state, and the second correction value and the third correction value obtained by correcting the reference fuel amount are set and output. (Steps S11 and S12).

As described above, in the present embodiment, the crank chamber pressure is detected, and the engine load is obtained from the peak value of the pressure. Therefore, the present embodiment is compared with the conventional device in which the engine load is obtained from the throttle opening. Therefore, the structure is simple because there is no need to provide a throttle position sensor around the throttle, and there is no problem that the throttle operation becomes heavy. In this embodiment, the peak pressure is obtained for each cycle of the engine, and the engine load is calculated from the peak pressure. Therefore, the responsiveness to the fluctuation of the engine load is extremely high, and the detection accuracy of the engine load and the acceleration state is high. . In the above embodiment, the ignition timing, the exhaust start timing,
Although the case of controlling the fuel increase has been described, the present invention can of course be applied to other control. Further, in the above embodiment, the case of the engine provided with the fuel injection valve has been described, but the present invention can of course be applied to a carburetor type engine.

[0016]

As described above, according to the control apparatus for a two-stroke engine according to the present invention, the engine control reference signal is obtained based on the engine speed, and the crankcase pressure peak value is determined to be larger or smaller than a predetermined peak value. Since different corrections are applied to the engine control reference signal, and the specific configuration in this case is determined, the structure is simple, there is no hindrance to the throttle operation, and the responsiveness and control accuracy can be improved. effective.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a control device of a crankcase compression type two-stroke engine according to an embodiment of the present invention.

FIG. 2 is an engine speed-crankcase pressure characteristic diagram for explaining a process of establishing the present invention.

FIG. 3 is a flowchart for explaining the operation of the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Crankcase compression type 2 cycle engine 15 Pressure sensor 12 Engine control unit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ identification code FI F02P 5/15 F (58) Field surveyed (Int.Cl. ⁷ , DB name) F02D 45/00 310 F02D 45/00 314 F02D 45/00 364 F02B 27/06 F02P 5/15

Claims (1)

(57) [Claims] 1. A crankcase compression system 2 for controlling an engine operation amount such as an ignition timing, an exhaust start timing, and a fuel amount according to an engine speed, an engine load, and an acceleration state.
The control device cycle engine, a pressure sensor for detecting the crank chamber pressure in the crank chamber or the scavenging passage, et
Find engine control reference signal based on engine speed
Together with the peak value of the detected pressure by the pressure sensor
Above the specified peak value and relative to the peak value of the previous cycle
If the rising value of the engine is smaller than the predetermined rising value,
While the control signal is output.
And outputs a first correction value obtained by correcting the gin control reference signal.
If the peak value is smaller than the specified peak value and the
If the rise value relative to the peak value is smaller than the specified rise value,
And outputting a second correction value obtained by correcting the engine control reference signal.
On the other hand, when large, the engine reference signal was corrected.
A control device for a crankcase compression type two-stroke engine, comprising: a control unit that outputs a third correction value .