JPH0861131A - Irregular combustion reducing device for two-cycle engine - Google Patents

Abstract

PURPOSE: To surely prevent the generation of irregular combustion even in the case where the weather condition is changed or where the dispersion of accuracy is generated in the production of engine. CONSTITUTION: An irregular combustion reducing device is provided with an irregular combustion detection means 69 for detecting irregular combustion of an engine 23, an engine combustion condition changing means 70 for changing combustion condition of the engine 23, and a control device 71 for controlling the engine combustion condition changing means 70 for feedback on the basis of the detecting signal of the irregular combustion detecting means 69.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an irregular combustion reducing device for a two-cycle engine mounted on a motorcycle or the like.

[0002]

2. Description of the Related Art In a two-cycle engine, especially in a low speed range, a misfire due to an increase in the amount of burnt residual gas after scavenging exhaust,
Ignition and the like due to the unburned residual gas after this misfire occurs irregularly, resulting in a so-called irregular combustion state.

In this irregular combustion state, the engine output becomes irregular and the load is adversely affected.
The engine itself vibrates irregularly due to the reaction force of the engine output, which causes uncomfortable vibration (for example, pitching) in a vehicle equipped with the engine.

Therefore, in order to prevent the irregular combustion, conventionally, the following measures may be taken.

That is, in the relationship between the throttle opening or the negative pressure of the intake pipe and the ignition timing or the size of the exhaust passage cross-sectional area in the middle of the exhaust passage, a correlation which is considered to be unlikely to cause irregular combustion is set in advance. Based on this, the ignition control device that adjusts the ignition timing is controlled, or the exhaust valve that adjusts the size of the exhaust passage cross-sectional area is controlled.

[0006]

By the way, since the above-mentioned correlation which is considered to be unlikely to cause irregular combustion becomes fixed once it is determined, weather conditions such as atmospheric temperature and weather (for example, Rainwater splashes on the outer circumference of the wall that makes up the combustion chamber and changes in the rain, which removes heat of vaporization, or when it is not, etc.), or when there is variation in accuracy during engine production. However, there is a problem in that it is not possible to deal with these, and therefore, it is not possible to sufficiently prevent irregular combustion based on the above-mentioned predetermined correlation.

[0007]

SUMMARY OF THE INVENTION The present invention has been made by paying attention to the above-mentioned circumstances. Even if the weather conditions change or the precision in engine production varies, asymmetric combustion can be prevented more reliably. The purpose is to do so.

[0008]

SUMMARY OF THE INVENTION To achieve the above object, an asymmetric combustion reducing device for a two-cycle engine according to the present invention comprises an asymmetric combustion detecting means 69 for detecting an asymmetric combustion of an engine 23 and a combustion state of the engine 23. The engine combustion state changing means 70 for changing the engine combustion state changing means 70 and the control device 71 for feedback-controlling the engine combustion state changing means 70 based on the detection signal of the irregular combustion detecting means 69.

[0009]

[Operation] The operation of the above configuration is as follows.

When the irregular combustion occurs in the engine 23, the irregular combustion detection means 69 immediately detects the irregular combustion, and the detection signal is input to the control device 71, which is feedback-controlled by the control device 71. 70 changes the combustion state of the engine 23, thereby preventing the irregular combustion of the engine 23.

Therefore, even if the weather condition changes or the precision of the engine 23 varies, the irregular combustion of the engine 23 is directly prevented regardless of the variation.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 2, reference numeral 1 in the drawing is a motorcycle, which is an example of a vehicle and is a saddle-ride type vehicle, and an arrow Fr indicates the front in the traveling direction. The right and left described below means the direction toward the front. Reference numeral 2 is a road surface on which the motorcycle 1 can travel.

The vehicle body 3 of the motorcycle 1 has a vehicle body frame 4 on the stationary side of the vehicle body. This body frame 4
Has a head pipe 5 at the front end thereof, and a pair of left and right main frames 6 extends rearward and downward from the head pipe 5, and further extends rearward and downward from the respective extended ends of the main frames 6. The seat pillar tube 7 extends. On the other hand, the down tubes 8 extend rearward and downward from the lower surfaces of the front portions of the main frames 6, and the extending ends of the down tubes 8 and the extending ends of the seat pillar tubes 7 are coupled to each other. There is.

A seat rail 10 extends rearward and upward from the rear portion of each main frame 6, and the seat rail 10 is supported by the seat pillar tube 7 by a pair of left and right back stays 11, 11. The portion where the back stays 11 and the seat pillar tubes 7 are connected to each other is a rear arm bracket 12.

A front fork 14 is rotatably supported on the head pipe 5. A front wheel 15 is supported on the lower end of the front fork 14, and the front wheel 1
A front fender 16 for covering the vehicle 5 from above is provided, and the front fender 16 is fixed to a middle portion of the front fork 14 in the vertical direction. On the other hand, a handle 17 is attached to the upper end of the front fork 14 of the above.

A pivot shaft 1 is attached to the rear arm bracket 12.
A rear arm 19 is pivotally supported by 8 so as to be vertically swingable. A rear wheel 20 is supported on the swinging end of the rear arm 19, and a shock absorber 21 is installed between the seat rail 10 and the rear arm 19.

The engine 2 which is an internal combustion engine in the space surrounded by the main frame 6, the seat pillar tube 7, and the down tube 8, that is, in the frame of the vehicle body frame 4.
3 is provided. The engine 23 is a two-cycle engine, and has a crankcase 24 and a cylinder 25 protruding upward from the crankcase 24.
It is detachably supported on the vehicle body frame 4 by fasteners. A power transmission device 26 is connected to the rear surface of the crankcase 24, and the rear wheel 20 is connected to the output side of the power transmission device 26 by a chain transmission mechanism 27.

The reed valve 2 is provided on the rear surface of the cylinder 25.
8, intake pipe 29, carburetor 30, and air cleaner 31
Are connected in this order, and the carburetor 30 is provided with a throttle valve. On the other hand, one end of an exhaust pipe 33 is connected to the front surface of the cylinder 25, the other end side of the exhaust pipe 33 extends rearward through the vicinity of the lower side of the down tube 8 and a silencer 34 is connected to the rear end thereof. ing.

A fuel tank 35 is supported on the main frame 6, and fuel is supplied from the fuel tank 35 to the carburetor 30. On the other hand, a seat 36 is supported on the seat rail 10. A side cover 37 is provided to cover the rear portion of the vehicle body 3 from each side thereof.

By driving the engine 23,
When the power is transmitted to the rear wheels 20 via the power transmission device 26, the chain transmission mechanism 27, etc., the motorcycle 1 is allowed to travel forward on the road surface 2.

In FIG. 1, a crankshaft 41 is housed in a crank chamber 40 in a crankcase 24 of the engine 23. The crankshaft 41 is the crankcase 2 described above.
4 is rotatably supported around its axis.

The cylinder 25 of the engine 23 includes a cylinder body 4 having a cylinder hole 42 whose axial center is substantially vertical.
3 and a cylinder head 44 attached to the protruding end of the cylinder body 43. Cylinder hole 4
A piston 45 is fitted in the shaft 2 so as to be slidable in the axial direction. The piston 45 is connected to the crankshaft 41 by a connecting rod 46.

The piston 45 is connected to the cylinder head 4
4 to a certain extent, the space surrounded by the cylinder head 44 and the piston 45 in the cylinder hole 42 becomes the combustion chamber 48. A spark plug 49 is attached to the cylinder head 44, and a discharge portion of the spark plug 49 faces the combustion chamber 48.

An intake port 51 is formed in the upper rear portion of the crankcase 24, and the reed valve 28 communicates with the intake port 51. A scavenging passage 52 that connects the crank chamber 40 to the combustion chamber 48 is formed in the cylinder body 43 around the cylinder hole 42, and a portion of the scavenging passage 52 that opens toward the combustion chamber 48 serves as a scavenging port 52a. Has become. Further, an exhaust port 54, which is an exhaust passage that connects the combustion chamber 48 to an exhaust passage 53 in an upstream end that is a front end of the exhaust pipe 33, has an exhaust port 54.
It is formed in the front part of 3.

The spark plug 49 is an electronic ignition circuit 5
6 is electrically connected (hereinafter, simply referred to as "connection"), and the ignition circuit 56 is connected to an electronic engine control device 57. Further, a crank angle detection sensor 58 for detecting the crank angle of the crank shaft 41 is provided, and the crank angle detection sensor 58 is also used for the engine control device 57.
It is connected to the.

In FIG. 1, when the engine 45 is driven, when the piston 45 moves from the bottom dead center position on the crankshaft 41 side (shown by the chain double-dashed line in FIG. 2) to the combustion chamber 48 side, the scavenging port is moved by the piston 45. 52a and the exhaust port 54 are closed in this order. Further, when the piston 45 moves to the combustion chamber 48 side in this way, the crank chamber 4
The inside of 0 is negative pressure. Then, the outside air 59, which is air, is sucked into the carburetor 30 through the air cleaner 31, and this is used as the intake air 60.

Next, fuel is supplied to the intake air 60 in the carburetor 30 to generate the air-fuel mixture 61. Then, the air-fuel mixture 61 is sucked into the crank chamber 40 through the intake pipe 29 and the reed valve 28. This is the "inhalation process".

On the other hand, after the scavenging passage 52 and the exhaust port 54 are closed as described above, if the piston 45 further moves to the combustion chamber 48 side, the air-fuel mixture that has already been sucked into the combustion chamber 48 is moved. 61 is compressed. This is the "compression process".

Just before the piston 45 reaches the top dead center (shown by the solid line in FIG. 1), the crank angle detecting sensor 58
At the desired crank angle detected by
At the desired ignition timing, the discharge portion of the spark plug 49 is discharged by the output signal from the ignition circuit 56 controlled by the engine control device 57. Then, the air-fuel mixture 61 is ignited and burned to expand the gas, which pushes the piston 45 back to the crank chamber 40 side after the piston 45 has passed the top dead center. This is the "explosion process".

By the movement of the piston 45 toward the crank chamber 40, the air-fuel mixture 61 sucked into the crank chamber 40 is pre-compressed. The reed valve 28 is closed by the pressure in the crank chamber 40 at this time.

During the movement of the piston 45 toward the crank chamber 40, first, the exhaust port 54 is opened. Then, the burnt gas of the air-fuel mixture 61 passes through the exhaust port 54, passes through the exhaust port 54 as the exhaust 62, and passes through the exhaust chamber 54.
Emitted from 8. This is the "exhaust process". Then, the exhaust gas 62 is discharged to the outside through the exhaust passage 53 in the exhaust pipe 33.

As described above, when the piston 45 moves toward the crank chamber 40 and the exhaust port 54 is opened, the scavenging port 52a is subsequently opened. Then, the air-fuel mixture 6 that has been pre-compressed in the crank chamber 40 as described above.
1 is made to flow into the combustion chamber 48 through the scavenging passage 52, and this air-fuel mixture 61 pushes out a part of the burned gas remaining in the combustion chamber 48 to the exhaust port 54, and
The air-fuel mixture 61 fills the combustion chamber 48. This is the "scavenging process". Then, after this, the piston 45 returns to the bottom dead center position.

From the above state, the piston 45 moves again to the combustion chamber 48 side, and the above-described steps are repeated to rotate the crankshaft 41. Then, the engine 23 outputs power through the crankshaft 41, and this power is transmitted to the rear wheel 20 via the power transmission device 26, the chain transmission mechanism 27, etc. as described above.

As shown in FIG. 1, there is provided an exhaust timing adjusting device 79 for adjusting the exhaust timing when the exhaust 62 is discharged from the combustion chamber 48 to the exhaust port 54 to improve the engine performance.

The device 79 has an exhaust timing adjusting valve 64 provided on the upper side of the exhaust port 54. When the exhaust timing adjusting valve 64 is opened and closed, the upper opening of the exhaust port 54 is opened and closed.
The position of the upper opening edge is variable in the vertical direction. An actuator 65 such as a servomotor operates the exhaust timing adjusting valve 64, and the actuator 65 is connected to the engine control device 57.

An engine speed sensor 67 for detecting the speed of the engine 23, that is, the speed of the crankshaft 41 is provided, and the engine speed sensor 67 is connected to the engine controller 57.

Then, the engine speed sensor 67
When it is determined that the engine 23 is in the high speed range by the detection signal of the above, the exhaust timing adjusting valve 64 is opened by the operation of the actuator 65 controlled by the engine control device 57, and the upper opening edge of the exhaust port 54 is opened. Are located above. Then, the exhaust timing becomes earlier, which improves the engine performance in the high speed range.

On the other hand, when it is determined that the engine 23 is in the middle or low speed range, the actuator 65 is closed, and the upper opening edge of the exhaust port 54 is positioned below. Then, the exhaust timing is delayed, which improves the engine performance in the middle and low speed ranges.

In FIGS. 1 to 3, the engine 23 is used.
Is provided with an irregular combustion reducing device for preventing irregular combustion. This device is based on an irregular combustion detection means 69 for detecting irregular combustion of the engine 23, an engine combustion state changing means 70 for altering the combustion state of the engine 23, and the detection signal of the irregular combustion detection means 69. A control device 71 for feedback controlling the combustion state changing means 70, and the control device 71 constitutes a part of the engine control device 57.

The irregular combustion detecting means 69 includes a combustion pressure sensor 72, a crank chamber pressure sensor 73, and a crankshaft rotation angular velocity sensor 74, which will be described later.

The combustion pressure sensor 72 detects the gas pressure during combustion of the air-fuel mixture 61 in the combustion chamber 48, and its detection signal is input to the control device 71.
The controller 71 calculates the indicated mean effective pressure (Pmi) for each cycle based on the detection signal. The Pmi average and standard deviation of several tens of consecutive cycles are calculated, and the value obtained by dividing the standard deviation by the average is defined as the combustion fluctuation rate. The combustion fluctuation rate is generally 0.
The area exceeding 2 is the irregular combustion area. Of course, the higher the number, the worse the degree.

The crank chamber pressure sensor 73 detects the gas pressure in the crank chamber 40, and the detection signal is input to the control device 71. The gas pressure in the crank chamber 40 changes due to irregular combustion. Therefore, in the same way as the combustion pressure sensor 72, the control device 71 obtains the average effective pressure and the standard deviation similarly to the gas pressure during combustion, and calculates the crank chamber pressure fluctuation rate. This may be used as a substitute characteristic of the combustion fluctuation rate.

The crankshaft rotation angular velocity sensor 74
Detects the rotational angular velocity of the crankshaft 41, and the detection signal is input to the control device 71. The control device 71 obtains the average and standard deviation of the rotation speeds of the crankshaft 41 in each cycle based on the detection signal.
The rest is the same as the calculation of the combustion fluctuation rate.

The crankshaft rotational angular velocity sensor 74 may detect the rotational angular velocity of the rotary shaft of the power transmission device 26 that rotates in conjunction with the crankshaft 41 or the axle of the rear wheel 20. However, since it is affected by the road surface 2 and the like, the magnitude (S / N) of the detection signal with respect to noise cannot be made very large.

The engine combustion state changing means 70 includes an ignition timing control device 76, an exhaust timing adjusting device 79, and an exhaust valve opening adjusting device 80, which will be described later.

The ignition timing control device 76 has a throttle opening sensor 77 for detecting the throttle opening in the carburetor 30.

In FIG. 3, this figure shows a flowchart of the control device 71 relating to the ignition timing control device 76, and (P-1) to (P-10) show each step of the program.

At (P-2), it is judged from the detection signal of the throttle opening sensor 77 whether or not the throttle opening in the carburetor 30 is substantially constant. If the throttle opening is almost constant, then in (P-3),
Based on the detection signal of the engine speed sensor 67, it is determined whether the engine speed is substantially constant. That is, (P
-2) and (P-3), it is determined whether or not the motorcycle 1 is traveling at a substantially constant speed.

As described above, when it is determined that the motorcycle 1 is traveling at a substantially constant speed, the throttle opening in the carburetor 30 is below a certain opening (1 / 6 to 1/8), and it is determined whether the load is low or medium (P-4).

If it is determined in (P-4) that the throttle opening is less than a certain opening, the engine rotation speed sensor 67 detects a signal and the engine 23 has a certain rotation speed less than a certain low speed. Or not (P-
5). That is, when the engine 23 has a low to medium load and a low to medium speed, irregular combustion is likely to occur. Therefore, it is determined whether the irregular combustion is likely to occur.

If it is determined from the above (P-4) and (P-5) that the engine 23 is in a state where irregular combustion is likely to occur, the irregular combustion detection means 69 determines whether the irregular combustion level is below the allowable value. It is judged (P-6).

In (P-6), firstly, when the irregular combustion detection means 69 is the combustion pressure sensor 72, the detection (measurement) time by the combustion pressure sensor 72 is 40 to 80 cycles ( (0.5 to 1.0 seconds in the normal range)
As a result, the combustion pressure fluctuation rate, which is the irregular combustion level at this detection time, is obtained. Experimentally, the allowable value based on this combustion pressure fluctuation rate is 0.2 or less. Since the above-mentioned allowable value differs depending on the vehicle, it may be experimentally determined.

Secondly, in the above (P-6), when the irregular combustion detecting means 69 is the crank chamber pressure sensor 73, it is the same as the irregular combustion detecting means 69, and the combustion pressure fluctuation rate is Should be replaced with the crank chamber pressure fluctuation rate. However, the allowable values are different.

Thirdly, in the above (P-6), the irregular combustion detecting means 69 is used for the crankshaft rotation angular velocity sensor 7
In the case of 4, the crankshaft rotation angular velocity sensor 74 detects the rotation angular velocity of the crankshaft 41 with the detection time of 0.2 to 0.5 seconds. The unpleasant frequency of the vehicle body 3 is 8 to 10 Hz, which is the front wheel 15 or the rear wheel 20.
Is the natural frequency of.

When the unpleasant frequency is generated, the engine 23
The number of rotations of fluctuates accordingly. Therefore, the rotation speed of the engine 23 is passed through a bandpass filter of 8 to 10 Hz to obtain the amplitude which is the irregular combustion level.

In (P-6) above, when the irregular combustion level exceeds a predetermined allowable value, the ignition timing is set to an allowable retard value (approximately 5 ° BTDC, that is, approximately 5 ° before the top dead center). It is determined whether or not it is within () (reference A of (P-7)).

In (P-7), if the ignition timing is within the allowable retard value, the ignition timing is slightly retarded by a preset amount (reference B of (P-8)). Then, the illustrated combustion efficiency at the time of combustion decreases, so that if the vehicle is going to travel with the same load, the throttle opening of the carburetor 30 must be opened accordingly. As a result, the residual ratio of burnt gas in the combustion chamber 48 decreases, and the misfire ratio decreases, that is, irregular combustion is prevented. After this, the process returns to (P-2).

As described above (P-6), when the irregular combustion level is equal to or lower than the allowable value, the ignition timing is set to the allowable advance value (approximately 3).
It is determined whether it is within 5 ° BTDC (reference C of (P-9)).

In (P-9), if the ignition timing is within the allowable advance value, the ignition timing is advanced slightly by a preset amount (reference D of (P-10)). After this, (P
Return to -2).

The exhaust timing adjusting device 79 constituting the engine combustion state changing means 70 has the exhaust timing adjusting valve 64, the actuator 65, and the control device 71 as constituent elements.

The control device 71 for the exhaust timing adjusting device 79 is the same as (P-1) to (P-6), but (P-7) to (P-10) are different. , (P-7) to (P-10) will be described.

In (P-6), when the irregular combustion level exceeds the allowable value, it is judged whether the exhaust timing is earlier than the maximum allowable delay (reference A in (P-7)).

In (P-7), if the exhaust timing is within the maximum allowable delay, the exhaust timing adjusting valve 64 is slightly closed, and the exhaust timing is delayed by a preset amount ((( Code B) of P-8).

Then, in the above "scavenging process", the exhaust timing adjusting valve 64 restricts the exhaust 62 from going out through the exhaust passage 53. Therefore, the gas pressure in the combustion chamber 48 becomes high and the temperature remains high. Then, this acts on the one that promotes the combustion of the air-fuel mixture 61, and the misfire rate decreases. In this case, the fuel economy is improved in combination with the reduction of blow-through.

In the same as above (P-6), when the irregular combustion level is equal to or less than the allowable value, it is judged whether the exhaust timing is later than the minimum allowable delay (reference C in (P-9)).

In the above (P-9), if the exhaust timing is later than the minimum allowable delay, the exhaust timing adjusting valve 64 is slightly opened as described above, and the exhaust timing is slightly advanced by a preset amount ((( Code D) of P-10).

The exhaust valve opening degree adjusting device 80 constituting the engine combustion state changing means 70 adjusts the opening degree of the exhaust passage 53 in FIG. 1 and suppresses the flow rate of the exhaust gas 62 flowing through the exhaust valve 81. have. This exhaust valve 81
Is operated by an actuator 82 such as a servomotor.
The actuator 82 is the control device 71.
Connected with.

The control device 71 for the exhaust valve opening adjusting device 80 is the same as the above (P-1) to (P-6), but (P-7) to (P-10) are different. Therefore, (P-7) to (P-10) will be described.

In (P-6), when the irregular combustion level exceeds the allowable value, it is judged whether the exhaust valve opening is equal to or larger than the minimum allowable opening (reference A in (P-7)).

In (P-7), if the exhaust valve opening is equal to or more than the minimum allowable opening, the exhaust valve 81 is slightly closed by a preset amount, and the exhaust passage 53 is slightly closed. (Code B of (P-8)).

Then, in the "scavenging process", the exhaust 62 may be directed to the outside through the exhaust passage 53.
Regulated by 1. Therefore, the gas pressure in the combustion chamber 48 becomes high and the temperature remains high. Then, this acts on the one that promotes the combustion of the air-fuel mixture 61, and the misfire rate decreases. In this case, the fuel economy is improved in combination with the reduction of blow-through.

In the same as above (P-6), when the irregular combustion level is below the allowable value, it is judged whether or not the exhaust valve opening is below the maximum allowable opening (reference C in (P-9)).

In (P-9), if the exhaust valve opening is less than the maximum allowable opening, the exhaust valve 81 is opened by a preset amount, and the exhaust passage 53 is opened slightly (( P
-10) code D).

The engine combustion state changing means 70 is used.
The ignition timing control device 76, the exhaust timing adjusting device 79, and the exhaust valve opening adjusting device 80 that constitute the above may be provided only one of them, or may be variously combined.

[0076]

According to the present invention, the irregular combustion detecting means for detecting irregular combustion of the engine, the engine combustion state changing means for changing the combustion state of the engine, and the detection signal of the irregular combustion detecting means are provided. The engine combustion state changing means is feedback-controlled.

Therefore, when the irregular combustion occurs in the engine, the irregular combustion is immediately detected by the irregular combustion detection means, and the detection signal is input to the control device, which is feedback-controlled by the control device. The combustion state of the engine is changed, which prevents the irregular combustion of the engine.

Therefore, even if the meteorological conditions change or the accuracy varies in engine production, the irregular combustion of the engine is directly prevented regardless of this, so that the irregular combustion is more reliable. Will be prevented.

[Brief description of drawings]

FIG. 1 is a partially enlarged sectional view of FIG.

FIG. 2 is an overall side view of the motorcycle.

FIG. 3 is a diagram showing a flowchart of a control device.

[Explanation of symbols]

 23 engine 57 engine control device 69 irregular combustion detection means 70 engine combustion state changing means 71 control device

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location F02D 45/00 368 S F02B 25/20 B F02D 9/04 H F02P 5/15

Claims (1)

[Claims] 1. An irregular combustion detecting means for detecting irregular combustion of an engine, an engine combustion state altering means for altering the combustion state of the engine, and an engine combustion state altering means based on a detection signal of the irregular combustion detecting means. A non-uniform combustion reducing device for a two-cycle engine including a control device for feedback control of