JP2607935B2 - Output control method for two-stroke engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Objects of the Invention (1) Field of Industrial Application The present invention relates to a method for controlling the output of a two-stroke engine in which an exhaust timing control valve is disposed at an exhaust port to control exhaust timing. .

(2) Prior Art Conventionally, there is well known a method of controlling the output of a two-cycle engine by thinning out the ignition timing.

(3) Problems to be Solved by the Invention However, when the output is controlled by thinning out the ignition timing as described above, the raw gas is contained in the exhaust gas, and the exhaust gas property becomes poor.

Therefore, by controlling the opening of an exhaust timing control valve provided in a two-stroke engine in accordance with the engine speed, the engine output is controlled while maintaining good exhaust gas properties (for example, Japanese Patent Laid-Open No. -20623 publication). Thus, in the above prior art in which the engine output is controlled by controlling the opening of the exhaust timing control valve, the engine output becomes maximum at each engine speed as shown by the broken line in FIG. The exhaust timing control valve is controlled as described above, and the engine output rises as the engine speed increases, but if the engine output rises sharply with respect to the driver's prediction, the impression that it is difficult to ride May give. Generally, an engine having such characteristics is called a peaky engine, but such a peaky engine is suitable for a motorcycle or a buggy for a driver who enjoys the fun by controlling the characteristics. Generally, it is often used in competition vehicles. However, in the vehicle used by ordinary drivers for touring or for beginners,
It is not preferable that the engine output rises sharply with respect to the engine speed, but it is desirable that the engine output be substantially constant with respect to the engine speed.

The present invention has been made in view of such circumstances,
It is an object of the present invention to provide a method for controlling the output of a two-cycle engine, which can prevent the engine output from rising sharply with respect to the engine speed.

B. Configuration of the Invention (1) Means for Solving the Problems The present invention relates to an output control method for a two-stroke engine in which an exhaust timing control valve is disposed at an exhaust port to control exhaust timing. The first feature is that the operation of the exhaust timing control valve is controlled so that the engine output becomes substantially constant regardless of the engine speed in the speed range.

The present invention also provides a method for controlling the output of a two-stroke engine in which an exhaust timing control valve is provided at an exhaust port to control the exhaust timing, wherein the engine output is substantially independent of the engine speed within a preset engine speed range. The second feature is that the ignition timing is controlled in addition to the operation control of the exhaust timing control valve so as to be constant.

(2) Operation According to the first feature, since the engine output is controlled by controlling the operation of the exhaust timing control valve, it is possible to maintain good exhaust gas properties and avoid a rapid rise in the engine output. .

According to the second feature, controlling the exhaust timing control valve and the ignition timing makes it more effective to keep the engine output substantially constant.

(3) Embodiment Hereinafter, an embodiment in which the present invention is applied to a motorcycle equipped with a two-cylinder two-cycle engine will be described with reference to the drawings. First, in FIG. A crankcase 1 having a chamber 1a, a cylinder block 2 having a cylinder hole 2a, and a cylinder head 3 are connected to each other in this order, and a piston 4 is slidably fitted in the cylinder hole 2a. A combustion chamber 5 is formed between the piston 4 and the cylinder head 3.

One side of the side wall of the cylinder block 2 has a cylinder hole 2a.
An intake / scavenging port 6 is provided which can communicate with the combustion chamber 5 and the crank chamber 1a in accordance with the movement of the piston 4 inside the cylinder. An exhaust port 7 that can communicate with the combustion chamber 5 is provided in accordance with the condition. The intake / scavenging port 6 is connected to a carburetor C (see FIG. 2) via a reed valve 8 disposed inside the outer end, and the exhaust port 7 is connected to an exhaust pipe (not shown).

A pair of scavenging ports 9a and 9b are provided on the side wall of the cylinder block 2 facing each other between the intake / scavenging port 6 and the exhaust port 7, respectively.
The a and 9b communicate between the crank chamber 1a and the combustion chamber 5 with the piston 4 at a position where the scavenging ports 9a and 9b are opened.

An ignition plug 10 is screwed into the cylinder head 3 with the electrode facing the combustion chamber 5.

Exhaust timing control device for controlling the opening timing of exhaust port 7, that is, the exhaust timing, in the downward stroke of piston 4
Reference numeral 11 includes an exhaust timing control valve 12 disposed at the upper edge of the inner end of the exhaust port 7, and a servo motor 13 for driving the exhaust timing control valve 12.

The exhaust timing control valve 12 has a base end of a valve body 16 fixed to a valve shaft 15 rotatably supported by the cylinder block 2. The valve body 16 is slidable between a fully open position where the valve element 16 is stored in the storage recess 14 provided on the upper inner surface of the upper portion 7 and a fully closed position where the valve element 16 projects from the storage recess 14 by a predetermined amount. Moreover, the distal end surface of the valve body 16 is formed in an arc surface that is substantially continuous with the inner peripheral surface of the cylinder hole 2a.

A driven pulley 17 is fixed to an end of a valve shaft 15 protruding from the cylinder block 2. An endless transmission cable 19 is fixed to the driven pulley 17 and a driving pulley 18 fixed to an output shaft of the servomotor 13. Be wound up. Therefore, the exhaust timing control valve 12 operates according to the operation of the servo motor 13. The servo motor 13 is provided with a potentiometer 20 for detecting the operation amount.

In FIG. 2, the operation of the servo motor 13 and the ignition timing of the ignition plugs 10 and 10 in the exhaust timing control device 11 are controlled by a control unit 21 composed of a microcomputer. , C, and the operation of the oil pump P are also controlled by the control unit 21.

Power source 22 is connected to the power input terminal I _A of the control unit 21.
The pulser coil 23 ₁ corresponding to the one of the cylinder control unit 21
It is connected to the pulse generator input terminal I _B1, I _C1, pulsar input terminal of the pulser coil 23 ₂ control unit 21 corresponding to the other cylinder
Connected to I _B2 and I _C2 .

The tachometer 24 is connected to a rotation speed input terminal _ID of the control unit 21. Also the control unit 21, in order to avoid the vehicle speed reaches the set speed or is provided with overspeed signal input terminal I _E, The overspeed signal input terminal I _E, the vehicle speed set value Is exceeded, a low-level signal is input from the speedometer 25.

The potentiometer 20 attached to the servo motor 13
Is connected to the A / D converter 26, converted into a digital signal by the A / D converter 26, the valve opening signal input terminal I _F of the control unit 21, is input to the I _G. The throttle opening of the pair of carburetors C and C individually corresponding to each cylinder is detected by a common potentiometer 27, and the throttle opening detected by the potentiometer 27 is subjected to A / D conversion. Container 2
After being converted into a digital signal in step 8, the signal is input to the throttle opening input terminals I _H and I _I of the control unit 21.

The control unit 21 has three switch signal input terminals I _J ,
I _K and I _L are provided, and these input terminals I _J , I _K and I _L
, Switches S ₁ , S ₂ , and S ₃ are individually connected.
These switches S ₁ , S ₂ , and S ₃ are used to determine whether the output of the two-cycle engine is controlled in the first or second control mode set in advance.
S _1, S when _{the 2} were passed the first control mode, also switches S _1, S ₃ when brought into conduction the input terminal I _J a signal indicating the second control mode, I _K, inputs to the I _L Is done.

The ignition plugs 10, 10 provided for each cylinder are
9 _1, 29 ₂ are connected individually to, the control unit 21, the ignition coil 29 ₁ to control the ignition timing by the spark plug 10, 10, 29
₂ are provided with ignition control output terminals O _A1 and O _A2 . Further, the carburetors C and C are provided with a pair of solenoid valves for controlling the bleed air of the main jet and the slow jet, respectively, and a solenoid for controlling the electromagnetic drive units 30 and 31 of the solenoid valves. valve control output terminal O _B, O _C is provided in the control unit 21.

The servo motor 13 operates in response to a drive signal from a drive circuit 32. The control unit 21 is provided with drive control signal output terminals O _D and O _E to supply a control signal to the drive circuit 32. The oil pump P for supplying lubricating oil to the two-cycle engine is a plunger type.
The oil pump P is provided with an electromagnetic drive unit 33 for controlling the discharge amount of the lubricating oil by changing the stroke of the plunger. The control unit 21 controls the discharge amount control so as to supply a control signal to the electromagnetic drive unit 33. signal output terminal O _F is provided.

The control unit 21 controls the ignition coil 2 according to the input signals from the pulsar coils 23 ₁ and 23 ₂ , the tachometer 24, the speedometer 25, the potentiometers 20 and 27, and the switches S ₁ , S ₂ and S _3.
9 ₁ , 29 ₂ , control signals are given to the electromagnetic drive units 30, 31, 33 and the drive circuit 32. In particular, the operation of the servo motor 13 via the drive circuit 32, that is, the opening of the exhaust timing control valve 12, Third
It is controlled according to the flowchart shown in FIG.

In FIG. 3, in a first step M1, reads the engine speed N _E, the throttle opening in the second step M2 theta _TH
, And in the next third step M3, the switches S ₁ , S ₂ ,
It reads the signal from the S _3. Further, in the fourth step M4 follows, determines one by one to control the two-stroke engine of the switches S _1, S _2, a signal from the S ₃ first and second control modes.

Meanwhile, the first and second map is the first control mode and a second control mode defining the opening of the exhaust timing control valve 12 corresponding to the engine speed N _E and the throttle opening theta _TH to the control unit 21 They are set in advance so as to correspond individually.
For example, in the first map, the valve opening as shown by the solid line in FIG. 4 is set when the throttle is fully open, and in the second map, the valve opening as shown by the broken line in FIG. 4 is set when the throttle is fully open. . The first map shows the engine speed.
When the N _E is in a certain range, which the engine output is set to the opening degree of the exhaust timing control valve 12 to be substantially constant, the exhaust timing control valve second map according to the engine speed N _E to which the present invention is set so as to increase the 12 opening of, it is obtained by setting the degree of opening of the exhaust timing control valve 12 to the small opening side in a certain range of the engine speed N _E.

When it is determined in the fourth step M4 that the control mode is the first control mode, the first map is searched in a fifth step M5, and then the target opening degree θ ₀ is set in a seventh step M7. When it is determined that the control mode is the second control mode, the second map is searched in the sixth step M6 and then the seventh control mode is executed.
In step M7, the target opening θ ₀ is set. Next 8th
In step M8, it calculates the difference Δθ read the current opening theta exhaust timing control valve 12, then the target opening theta ₀ in the ninth step M9 and the current opening theta.

In a tenth step M10, the drive current of the servo motor 13 is determined according to the absolute value of the difference Δθ. This drive current is chopped by a plurality of duty ratios and is determined, for example, for each of the Δθ regions set for each of a plurality of regions, thereby improving the operation followability of the exhaust timing control valve 12. Further, in an eleventh step M11, the servo motor 1
The operation of the servo motor 13 is controlled by deciding whether to operate the motor 3 in the forward or reverse direction and outputting a control signal to the drive circuit 32 in a twelfth step M12.

Next, the operation of this embodiment will be described. When the driver of the motorcycle operates the switches S ₁ , S ₂ , S ₃ , the output control mode of the two-stroke engine is changed to one of the first and second control modes. Can be set alternatively,
When in a certain range of the engine speed N _E when selecting the first control mode is made possible to maintain substantially constant engine output.

Also when selecting the second control mode occurs in response to an increase in the engine speed N _E can be increased engine output may be an engine having a so-called peaky characteristics.

In this way, by controlling the operation of the exhaust timing control valve 12, the output of the two-cycle engine is controlled.
It is possible to control the engine output while avoiding deterioration from the exhaust gas properties, and when the first control mode is selected, it is possible to keep the engine output substantially constant within a certain range.

As another embodiment of the present invention, not only the opening degree of the exhaust timing control valve 12 is controlled as described above, but also the ignition timing may be controlled together. This will be described with reference to the main routine in the figure and the subroutine in FIGS. 5A and 5B.

First, in the main routine shown in FIG. 5, the first to fourth steps L1 to L4 are the same as those in FIG. 3 in the above-described embodiment. At step L5, the process according to the first subroutine of FIG. 5A is performed, and when it is determined that the control mode is the second control mode, the process according to the second subroutine of FIG. 5B is performed.

Incidentally, the control unit 21 the engine speed N _E and the first and second map is the first control mode defining the opening and the ignition angle of the exhaust timing control valve 12 corresponding to the throttle opening theta _TH and the second in It is set in advance corresponding to each control mode. For example, in the first map, the valve opening and the ignition angle as shown by the solid line in FIG. 4 are set when the throttle is fully open, and in the second map, the valve opening and the ignition as shown by the broken line in FIG. Corners are set. The first map Thus, when the engine speed N _E is in a range is used to set the opening and the ignition angle of the exhaust timing control valve 12 so that the engine output is substantially constant, the engine rotational in a range exhaust timing number N _E control valve 12
Is set to be lower than the second map, and the ignition angle is set to be more retarded than the second map.

In the first subroutine of FIG. 5A, the first step N1
Then, the target opening θo is retrieved from the first map,
In step N2, the target opening degree θo is set. The next third
In step N3, the target ignition angle θig is retrieved from the first map, and in fourth step N4, the target ignition angle θig is set. In the second subroutine of FIG. 5B, in a first step N1 ', a target opening θo is searched from a second map, and in a second step N2', the target opening θo is set.
In a third step N3 ', the target ignition angle .theta.
The target ignition angle θig is set in a fourth step N4 ′.

Seventh step L7 to eleventh step L1 after the processing according to the first or second subroutine as described above is completed.
In 1, the drive current is set based on the difference between the target opening degree θo and the actual opening degree θ, and a control signal for driving the servomotor 13 is output after the output polarity is determined.

In the next twelfth step L12, a counter is set according to the target ignition angle θig, and in a thirteenth step L13, it is determined whether or not a count start condition by the counter is satisfied. The counting is performed in L14 and the fifteenth step L15, and when the counting is completed, the ignition by the spark plug 10 is performed in a sixteenth step L16.

By using the opening degree control and the ignition timing control of the exhaust timing control valve 12 in this manner, it is possible to more effectively suppress the increase in the engine output and control the engine output to be substantially constant in a certain engine speed range. Becomes

C. Effects of the Invention As described above, according to the first feature of the present invention, the operation of the exhaust timing control valve is controlled so that the engine output becomes substantially constant regardless of the engine speed within a preset engine speed range. As a result, the engine output can be kept almost constant within a certain engine speed range regardless of the engine speed while maintaining good exhaust gas properties. It is effectively avoided that the vehicle suddenly rises, so that a vehicle that is easy for beginners and general drivers to handle and to ride on is obtained.

Further, according to the second feature of the present invention, since the ignition timing is controlled in addition to the control of the exhaust timing control valve so that the engine output becomes substantially constant in the preset engine speed range, the engine output is further reduced. By controlling effectively, an almost constant holding state of the engine output in a certain engine speed range is more reliably obtained, and thus the effect of the first feature is more reliably achieved.

[Brief description of the drawings]

1 to 4 show an embodiment of the present invention. FIG. 1 is a longitudinal sectional view of a main part of a two-stroke engine, and FIG.
FIG. 3 is a control circuit diagram, FIG. 3 is a flowchart showing a control procedure, FIG. 4 is a characteristic diagram of the opening degree of the exhaust timing control valve, the ignition timing and the engine output with respect to the engine speed, FIG.
5A and 5B show another embodiment of the present invention. FIG. 5 is a flowchart showing a control main routine, and FIGS. 5A and 5B are flowcharts showing a subroutine. 7 Exhaust port, 12 Exhaust timing control valve

Claims (2)

(57) [Claims] 1. An output control method for a two-stroke engine in which an exhaust timing control valve is disposed at an exhaust port to control exhaust timing, wherein the engine output is substantially independent of the engine speed within a predetermined engine speed range. An output control method for a two-stroke engine, comprising: controlling an operation of an exhaust timing control valve so as to be constant. 2. An output control method for a two-stroke engine in which an exhaust timing control valve is disposed at an exhaust port to control exhaust timing, wherein the engine output is substantially independent of the engine speed within a predetermined engine speed range. An output control method for a two-stroke engine, characterized by controlling an ignition timing in addition to an operation control of an exhaust timing control valve so as to be constant.