JP2813227B2 - Fuel injection system for crankcase preload type two-stroke engine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a fuel injection device for a two-cycle engine that calculates a fuel injection amount using a throttle valve opening and an engine rotation speed.

(Background of the Invention) In a two-stroke engine, when the vehicle is re-accelerated immediately after deceleration, the rotation does not rise smoothly, which may cause the engine to breathe and may cause unstable idling after deceleration. These are because the air-fuel mixture becomes excessively rich at the time of deceleration, and the combustion deteriorates and becomes unstable.

Therefore, it has been conventionally proposed to reduce the fuel injection amount during deceleration. For example, there is one that detects the rotation (close movement) of the throttle valve in the closing direction to reduce the injection amount. However, in this case, if the throttle valve stops, the decrease in the injection amount stops even when the rotation of the engine is decelerating, and the injection amount during normal operation, that is, the reference injection amount is injected. For this reason, if the throttle valve is rapidly closed and its opening / closing is stopped, a state occurs in which the injection amount is insufficiently reduced or the injection amount is hardly reduced, and the mixture becomes rich. As a result, there has been a problem that the above problem cannot be sufficiently solved.

(Object of the Invention) The present invention has been made in view of such circumstances,
Provided is a fuel injection device for a two-stroke engine, which is capable of appropriately adjusting the concentration of an air-fuel mixture during deceleration, smoothing re-acceleration after deceleration, stabilizing idling operation after deceleration, and suitable for exhaust gas purification during deceleration. The purpose is to:

(Constitution of the Invention) According to the present invention, it is an object of the present invention to provide a fuel injection device applied to a crankcase preload type two-cycle engine that injects a predetermined fuel injection amount according to an operation state from an injection valve. Closing movement detecting means for detecting movement, engine rotational speed detecting means, deceleration determining means for determining whether or not the engine is decelerating based on the engine rotational speed output from the engine rotational speed detecting means, and deceleration of the engine. A memory for storing a correction coefficient of the injection amount during the rotation, a correction amount calculating means for obtaining a correction coefficient during deceleration from the memory based on a throttle valve closing signal output from the closing movement detecting means, and a constant engine speed. In other words, until the throttle valve starts to rotate in the opening direction and the deceleration state ends, the injection amount calculating means that continues to correct the injection amount using the obtained correction coefficient. And a crankcase preloading type 2 having a step.
This is achieved by a fuel injection device for a cycle engine.

(Embodiment) FIG. 1 is an overall configuration diagram of one embodiment of the present invention, FIG. 2 is a block diagram of the control device, FIGS. 3A and 3B are diagrams showing contents stored in respective memories, and FIG. Is a flowchart of the operation.

In this figure, reference numeral 10 denotes a crankcase preload type two-stroke internal combustion engine, 12 denotes a cylinder, 14 denotes a piston, 16 denotes a spark plug, 18 denotes a crankcase, 20 denotes a crankshaft, and 22 denotes a connecting rod. A crank chamber 24 is formed in the crank case 18.

Reference numeral 26 denotes a throttle body, the downstream side of which is connected to an intake port 30 via a reed valve 28 as a one-way valve. A plate-like valve body 26a as a throttle valve is attached to the throttle body 26, and the valve body 26a
Move diagonally within 32. That is, the valve body 26a moves forward and backward from above the throttle body 26 such that the lower end of the valve body 26a is displaced downstream of the intake passage 32. The upper portion of the valve body 26a is connected to the pivot end of the lever 26b by a link 26c. Lever 26
b rotates in conjunction with a throttle operation mechanism such as an accelerator pedal or an accelerator grip, and eventually the valve element 26a is opened and closed by the throttle operation mechanism.

34 is an exhaust port, and 36 is an exhaust passage. Numeral 38 denotes a scavenging port, and this scavenging port 38 communicates with the crank chamber 24 through a scavenging passage 40.

42 is a fuel tank, 44 is a strainer for removing dust in the fuel, and 46 is an electric fuel pump. Numeral 48 denotes an electromagnetic fuel injection valve to which fuel pumped from a fuel pump 46 is supplied. Reference numeral 50 denotes a pressure regulator which keeps a constant fuel pressure fed from the fuel pump 44 to the injection valve 48. That is, when the fuel pressure supplied from the fuel pump 46 to the injection valve 48 becomes equal to or higher than a predetermined pressure, the pressure regulator 50 opens and a part of the fuel is returned to the fuel tank 42 via the pipe 52. Note that the adjustment pressure of the pressure regulator 50 may be changed in accordance with the intake negative pressure, that is, the pressure of the room formed between the valve body 26a and the reed valve 28. In this case, the injection valve 48
The control accuracy of the injection amount at the time of low-speed operation in which the injection time is extremely short can be improved.

56 is a pressure detector attached to the crankcase 18. The pressure detector 56 detects an internal pressure P of the crank chamber 24 and outputs an electric signal whose voltage changes in response to the change of the internal pressure P, that is, a pressure signal p. 58 is a potentiometer for detecting the throttle valve opening Θ, and the lever 26b
The throttle valve opening Θ is detected from the rotation angle of the throttle valve.

Numeral 60 is a control device composed of digital arithmetic devices,
The optimum fuel injection amount M for the operating state is calculated using the pressure signal p output from the pressure detector 56, the rotation speed N of the crankshaft 20, and the throttle valve opening Θ. Then, an injection signal I indicating an injection time width corresponding to the injection amount M is sent to the injection valve 48 in synchronization with the rotation angle θ of the crankshaft 20. The electromagnetic solenoid of the injection valve 48 opens at a predetermined timing for a predetermined time width according to the signal I, and injects the fuel of the injection amount M.

As shown in FIG. 2, the control device 60 includes an injection amount calculating means 62, a correction amount calculating means 64, a throttle valve closing movement detecting means 66, a deceleration determining means 68, and memories 70 and 72.
The injection amount calculation means 62 obtains a reference injection amount m based on the crank chamber pressure p and the rotation speed N of the crankshaft 20 obtained by an angle sensor (not shown) as rotation speed detection means. Here, the reference injection amount m is corrected by a correction coefficient α at the time of deceleration described later, and an optimum injection amount M is finally obtained by M = mα. The reference injection amount m is obtained based on the injection amount characteristic diagram shown in FIG. 3A stored in the memory 70. That this characteristic diagram is mapped from the peak value p _m or fluctuation width Δp it is changed by the intake air amount, a reference injection amount m that is determined by the rotational speed N and peak value p _m or fluctuation width Δp of the crank chamber pressure p Is represented by In addition, in the injection amount calculating means 62, the intake air temperature T _a obtained from the temperature sensor 74 provided on the stottle body 26,
Engine temperature obtained by the temperature sensor 76 provided on the cylinder head
Such as T _b, may be corrected with this injection amount m by information indicating other operating conditions.

The throttle valve closing movement detecting means 66 detects the throttle valve opening degree Θ
And the difference Θ−Θ ′ between the current value of
When this is negative, it is determined that the throttle valve is rotating in the closing direction (during closing movement), and a closing signal a is sent to each of the means 62 and 64. The correction amount calculating means 64 calculates a correction coefficient α for the engine speed N from the correction characteristic diagram of FIG. 3B stored in the memory 72 based on the closing signal a. The injection amount calculation means 62 corrects the above-mentioned reference injection amount m by the correction coefficient α to obtain an injection amount M = mα.

The deceleration determining means 68 determines whether or not the engine is decelerating. If the engine is decelerating, the correction by the correction coefficient α is continued even if the throttle valve is closing or stopping. Here, the fact that the engine is decelerating can be determined by the fact that the engine rotation speed N is being decelerated and is not yet constant, and that the throttle valve has not started to rotate in the opening direction.

When the injection amount M is obtained in this manner, an injection signal I having a time width corresponding to this is intermittently sent to the injection valve 48 in synchronization with the crank angle θ, and the electromagnetic solenoid in the injection valve 48 Operated by signal I to open injection valve 48. The control device 60 determines the time width of the injection signal I so as to be optimal in accordance with the driving situation.

Next, the operation of this embodiment will be described. When the internal pressure of the crank chamber 24 decreases due to the rise of the piston 14, the intake air flows from the intake passage 32 into the crank chamber 24 via the reed valve 28. Since a predetermined amount of fuel is injected from the fuel injection valve 48 in synchronization with the rotation of the crankshaft 20, the fuel is mixed with the intake air to form a mixture, and this mixture flows into the crank chamber 24. . When the piston 14 descends, the air-fuel mixture is pre-pressurized in the crank chamber 24. Here, the internal pressure P of the crank chamber 24 corresponds to the amount of intake air and changes substantially in synchronization with the rotation of the crankshaft 20. The internal pressure P is detected by the detector 56, while obtaining the peak value p _m or variation Δp of the output p during one cycle, the rotational speed N may detect and determine the amount of intake air (Figure 4, step 100 ). The injection amount calculating means 62 of the control device 60 obtains a reference injection amount m according to the operating condition at this time using a map (FIG. 3A) (step 10).
2). If the throttle valve closing movement detecting means 66 does not detect the closing movement of the throttle valve, the engine is operated with the reference injection amount m. When the throttle valve closing movement detecting means 66 detects the closing movement (step 104), the correction amount calculating means 64 obtains a correction coefficient α (step 106). The injection amount calculation means 62 calculates M
= Mα to determine the injection amount M (step 108). Next, when the deceleration determination means 68 detects the deceleration of the engine (step 110), the correction amount calculation means 62 continues to calculate the correction coefficient α even if the throttle valve is not being closed, and the injection amount calculation means 62 determines that M = The injection amount M is continuously reduced by mα. When the engine is rotated at a constant speed or the throttle valve is rotated in the opening direction, the injection amount calculation means 62 stops correcting the injection amount,
The reference injection amount m is injected with M = m.

In the embodiment described above, the crank chamber pressure P is detected by the pressure detector 56, and the intake air amount and the fuel injection amount m are obtained from the pressure P. However, the present invention may instead use another means to detect the intake air amount and control the injection amount.

(Effect of the Invention) As described above, the present invention detects the closing movement of the throttle valve and corrects the injection amount during deceleration so as to reduce the injection amount. Since the injection amount is continuously reduced while the throttle valve is not rotated in the opening direction, even when the throttle valve is suddenly closed and stopped, the injection amount is continuously reduced, and the concentration of the air-fuel mixture is maintained. Is properly maintained. Therefore, when the engine is re-accelerated after deceleration, the engine does not breathe due to the rich air-fuel mixture, and smooth re-acceleration becomes possible. Further, the idling operation can be stabilized. Furthermore, the amount of unburned gas emitted during deceleration is reduced, and exhaust gas can be purified. Furthermore, the correction amount calculating means obtains a correction coefficient based on a signal (throttle valve closing movement signal) indicating the closing movement of the throttle valve output from the closing movement detecting means, so that the injection is quickly performed in conjunction with the closing movement of the throttle valve. The responsiveness is good because the amount can be reduced and there is no need to wait for the engine speed to actually drop. Therefore, a sufficiently high responsiveness can be obtained even if the air-fuel mixture enters the fuel chamber via the crank chamber by a pre-compression type.

[Brief description of the drawings]

1 is an overall configuration diagram of one embodiment of the present invention, FIG. 2 is a block diagram of the control device, FIGS. 3A and 3B are diagrams showing contents stored in respective memories, and FIG. 4 is a flowchart of operation. It is. 10 ... engine, 60 ... control device, 62 ... injection amount calculating means, 64 ... correction amount calculating means, 66 ... throttle valve closing movement detecting means, 68 ... deceleration determining means.

Continuation of the front page (56) References JP-A-59-5875 (JP, A) JP-A-1-271625 (JP, A) JP-A-2-1992111 (JP, A) JP-A-3-229937 (JP) JP-A-63-186943 (JP, A) JP-A-61-142343 (JP, A) JP-A-1-121537 (JP, A) JP-A-1-159150 (JP, U) (58) Field surveyed (Int. Cl. ⁶ , DB name) F02D 41/00-41/40

Claims (1)

(57) [Claims] 1. A fuel injection device applied to a crankcase preload type two-cycle engine that injects a predetermined fuel injection amount according to an operation state from an injection valve, wherein a closing movement detecting means for detecting closing movement of a throttle valve. An engine rotational speed detecting means, a deceleration determining means for determining whether or not the engine is decelerating based on the engine rotational speed outputted by the engine rotational speed detecting means, and a correction coefficient for the injection amount during deceleration of the engine. A correction amount calculating means for obtaining a correction coefficient during deceleration from the memory based on a throttle valve closing movement signal output by the closing movement detecting means; and a throttle valve rotating in an opening direction when the engine rotation speed becomes constant. And an injection amount calculating means for continuously correcting the injection amount by using the obtained correction coefficient until the deceleration state ends after the operation is started. Fuel injection device for crankcase preload type two-cycle engine.