JPH02204645A - Fuel controller for engine - Google Patents

Abstract

PURPOSE:To expand a fuel-cut range by resetting a fuel supply when a throttle valve is once operated in the more opening direction than the specified valve opening through fuel-cut rotational frequency, while maintaining the fuel supply unless it becomes more than the fuel-cut rotational frequency. CONSTITUTION:When valve opening of a throttle valve being detected by a valve opening detecting means is less than the specified value as well as when it is detected by a speed detecting means and engine speed is more than fuel-cut rotational frequency, a fuel-cut means controls a fuel supply means, performing a fuel cut, and when it becomes less than reset rotational frequency, a first resetting means resets the fuel supply. When the valve opening of the throttle valve is once operated in the more opening direction than the specified valve opening after entering the speed range through fuel-cut rotational frequency at the range between the fuel-cut rotational frequency and the resetting rotational frequency, a second resetting means rests the fuel supply, while this fuel supply resetting is maintains unless it becomes more than the fuel-cut rotational frequency. Thus the fuel-cut range can be expanded without any torque shock.

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to an engine fuel/W control device.

(Prior art) Conventionally, from the viewpoint of improving fuel efficiency, exhaust purification performance, etc.
During deceleration, fuel is cut as shown in Japanese Patent Publication No. 63-16576. Such deceleration fuel cut is mainly performed when the engine speed is equal to or higher than a predetermined fuel cut speed, or after passing through the fuel cut speed to a return speed lower than the fuel cut speed, and when the throttle valve is The deceleration fuel cut is performed when the valve opening is less than a predetermined valve opening (for example, fully closed), and in order to execute the deceleration fuel cut, the engine rotation speed and the throttle valve opening are required. Both must simultaneously satisfy predetermined conditions for fuel cut.

Therefore, when the engine speed satisfies the conditions, whether or not to execute deceleration fuel cut is determined by the valve opening state of the throttle valve, and the throttle valve opening is frequently cut by the driver's accelerator pedal operation. If the predetermined conditions are met or not, execution/non-execution of the deceleration fuel cut will be repeated.

Even if this repetition of execution/non-execution of deceleration fuel cut is performed in the high engine speed range,
The deceleration force is large and torque shock is hardly a problem, but at low engine speeds, the deceleration force is small, so torque shock (hunting) is often felt when deceleration fuel cut is executed or not. I will do it.

In order to solve such problems, conventionally, the fuel cut-off rotation speed and the return rotation speed are generally set high to make it difficult to experience torque shock.

(Problem to be solved by the invention) However, when the fuel cut speed and return speed are set high overall as described above, when the deceleration fuel cut is executed or not, the engine speed Even when the number is between the fuel cut rotation speed and the return rotation speed,
This will lead to deterioration in fuel efficiency, exhaust purification performance, etc.

The present invention has been made in view of the above-mentioned circumstances, and its purpose is to expand the fuel cut region to the low rotation speed side without causing torque shock in an engine fuel control device that performs deceleration fuel cut. It is in.

(Means and operations for solving the problem) In order to achieve the above object, the present invention includes a fuel supply means for supplying fuel to the engine, and a valve opening degree detector for detecting the valve opening degree of the throttle valve. means, a rotation speed detection means for detecting the engine rotation speed, and the fuel supply means when the valve opening degree of the throttle valve is less than or equal to a predetermined valve opening degree and the engine rotation speed is equal to or higher than the fuel cut rotation speed. a fuel cut means that performs a fuel cut by controlling the fuel cut speed; a first return means that restores fuel supply when the return speed becomes lower than the fuel cut speed; In the rotational speed region between the rotational speed and the fuel cut rotational speed, the fuel cutoff rotational speed belongs to the rotational speed region, and once the valve opening of the throttle valve is operated in the opening direction than the predetermined valve opening. A fuel control device for an engine, comprising: a second return means for restoring the fuel supply and for maintaining the restoration of the fuel supply as long as the fuel cut-off rotation speed is not exceeded. be.

With the above configuration, when the engine speed is transitioning from the fuel cut speed to the return speed, the valve opening of the throttle valve is frequently set to the predetermined condition for fuel cut by operating the accelerator pedal. Even if the conditions are met or not, deceleration fuel cut is prohibited, so torque shock will not occur even if the fuel cut conditions for engine speed (fuel cut speed, return speed) are as low as possible. become. Therefore, the fuel cut region can be expanded to the low rotational speed side without causing torque shock.

(Example) Hereinafter, an example of the present invention will be described based on the attached drawings.

In FIG. 1, reference numeral l denotes a four-cycle reciprocating type Otto-type engine body, and as is known, this engine body 1 is fitted into a cylinder block 2, a cylinder head 3, and a cylinder 2a of the cylinder block 2. A combustion chamber 5 is defined by the inserted piston 4. A spark plug 6 is disposed in the combustion chamber 5, and an intake boat 7 and an exhaust boat 8 are opened, and each boat 7.8 is
The intake valve 9 or the exhaust valve 10 opens and closes at known timing in synchronization with the engine output shaft.

In the intake passage 21 connected to the intake boat 7, from the upstream side to the downstream side, an air cleaner 22, an intake air temperature sensor 23 that detects the intake air temperature, an air flow meter 24 that detects the amount of intake air, a throttle valve 25, and a surge tank are installed. 26
, a fuel injection valve 27 is provided. .

Reference numeral 31 in FIG. 1 is a control unit constituted by a microcomputer, and this control unit 31 receives signals from the sensors 23, 24, ON-OFF signals from the idle switch 32, and sensors 33, 34. A signal from the battery 35 and a battery voltage signal from the battery 35 are input. The idle switch 32 detects whether the throttle valve 25 is fully closed, the sensor 33 detects the engine cooling water temperature, and the sensor 34 is attached to the destroyer 36 and measures the crank angle, that is, the engine rotation speed. It is something to detect. on the other hand,
The control unit 31 outputs a predetermined signal corresponding to the amount of fuel to be injected to the fuel injection valve 27.

Next, the outline of the control contents of the control unit 31 will be explained with reference to FIGS. 2 and 3 in comparison with the conventional case.

First, in the conventional case (shown in FIG. 5), from a state where the engine speed is equal to or higher than the fuel cut speed, the fuel cut speed (shown as F/C speed in FIG. 5) and the return speed are changed. (shown as F/C return rotation speed in Fig. 5), if the idle switch 32 is frequently turned 0N-OFF by operating the accelerator pedal, the deceleration fuel Since the cut conditions are met, the idle switch 32 is turned on and off.
F (valve opening degree of the throttle valve 25) determines whether or not to execute the deceleration fuel cut (in Fig. 5, execution of the deceleration fuel cut is shown as F/C1 non-execution is shown as Inj). Execution and non-execution will be repeated as the idle switch 32 turns ON-OFF. Therefore, torque shock (hunting) frequently occurs due to repeated execution and non-execution of deceleration fuel cut.

Therefore, in this conventional case, as a solution to this problem, the fuel cut-off rotation speed and the return rotation speed are set high as a whole, thereby making the torque shock less noticeable.

However, such a solution would conventionally lead to poor fuel efficiency.

On the other hand, in the case of this embodiment (shown in FIG. 2), the engine speed is the fuel cut speed (for example, 25
0Or, p, m-) and return rotation speed (e.g. 1500r,
When the deceleration fuel cut condition is satisfied in the rotation speed region between p, m, ), once the idle switch 32 is set to 0FF (throttle valve 25 open), deceleration fuel cut is prohibited ( After that, the idle switch 3
Even if 2 is turned ON, the restoration of fuel supply (prohibition of fuel cut) continues as long as the engine speed does not become lower than the fuel cut speed.

As a result, even if the idle switch 32 is repeatedly turned ON and OFF due to frequent accelerator pedal operation in a state where the engine speed satisfies the deceleration fuel cut condition between the fuel cut speed and the return speed, the fuel supply is stopped. Since the return is maintained, torque shock will not occur. Therefore, it is possible to set the fuel cut-off rotation speed and the return rotation speed low, and the problems of torque shock and fuel consumption can be solved at the same time.

Details of the control content of the control unit 31 described above will be explained in detail with reference to the flowchart shown in FIG. Of course, the control unit 31 basically includes OPU, ROM, C1, .
, OCK, an A/D or D/A converter, and an input/output interface, but since these are known configurations when using a microcomputer, their explanation will be omitted. Note that in the following explanation, P does not represent a step.

First, l) In I, it is initialized and the flag N5W=
It is set to 0. This flag NSW indicates whether or not the engine speed N satisfies the deceleration fuel cut condition (fuel power/ant zone). When flag N5W=0, it means that the condition is not satisfied, and flag N5W=1 means that the condition is met.

Next, at P2, engine speed N, intake air amount Q
, intake air temperature, ON-OFF signal of the idle switch 32, engine coolant temperature, battery voltage, etc. are read.

Next, in P3, the basic fuel injection amount TP is calculated based on the intake air ffi Q and the engine rotation speed N (1).
3, where K is a constant), in P4, a correction value TV is calculated based on the battery voltage, and in P5, a correction value CTOTA L is calculated based on the engine cooling water temperature, intake air temperature, etc. Then, in the first P6, the final fuel injection amount TI is determined by multiplying 1'P of P3 by CTOTAL of P5 and adding TV of P4.

Next, in P7, it is determined whether the engine speed N exceeds the fuel cut speed. P7 is YES
At this time, since the engine speed N satisfies the deceleration fuel cut condition, the flag N5W is set to 1 in P8, and the process proceeds to the next P9.

At P9, it is determined whether the idle switch 32 is ON or not. When P9 is YES, throttle valve 2
Since the valve opening of 5 also satisfies the deceleration fuel cut condition,
At PIO, deceleration fuel is cut (TI=O).

When P9 is NO, the engine speed N satisfies the fuel cut condition, but the valve opening of the throttle valve 25 does not satisfy the fuel cut condition, and in this case, p
At H, flag N5W is reset to 0, and PI2
At , fuel injection is performed based on the TI of []6. The significance of pH will be explained in PI4 below.

When P7 is No, the engine speed N is less than or equal to the fuel cut speed, and in this case, it is determined in PI3 whether the engine speed N is less than the return speed.

When PI3 is No, this means that the engine speed N is equal to or higher than the return speed, so it is determined in PI4 whether flag N5W=1. This PI4 indicates whether or not the engine speed is within the speed range between the fuel cut speed and the return speed, but it satisfies the deceleration fuel cut condition. This is provided in order to once exceed the number and then judge whether or not it exists between the fuel cut rotation speed and the return rotation speed. This allows the previously mentioned pH
, even though the engine speed N satisfies the fuel cut condition, the idle switch 32 is turned 0FF.
If the flag N5W is forcibly set to O due to (throttle valve 25 open), the engine speed is in the speed range between the fuel cut speed and the return speed. In some cases, the engine speed is treated in the same way as if the engine speed does not satisfy the fuel cut condition.

When this PI4 is YES, since the engine speed N satisfies the fuel cut condition, the process proceeds to P9, where it is determined whether or not the idle switch 32 satisfies the fuel cut condition. When ,
Since the engine speed does not satisfy the fuel cut condition, the process proceeds to step 1''IiI PI2 and fuel is supplied.

When P13 is YES, it means that the engine speed N is less than the return speed and does not satisfy the fuel cut condition, and in this case, in PI5, the flag N5W=
It is reset to 0, and then the process proceeds to P12, where fuel supply is performed.

Although the embodiments have been described above, the present invention includes the following.

■Vary the fuel cut speed according to the degree of engine warm-up (engine cooling water temperature, etc.), load (N range - ○ range, presence or absence of air conditioner, etc.), and the condition of each part of the engine.

(2) The return rotation speed is set mainly by hysteresis, and a certain value is subtracted from the fuel cut rotation speed.

■As a valve opening detection means for the throttle valve 25, a throttle valve opening switch is used, and a set value (determine the throttle valve opening during steady driving in advance and set a value by subtracting it somewhat from that value) As a basis, it is determined whether the fuel cut condition regarding the valve opening degree is satisfied.

(2) Use an accelerator pedal switch as a valve opening detection means for the throttle valve 25.

■Stopping fuel supply to all cylinders or 3/6 cylinders as a deceleration fuel cut.

(Effects of the Invention) As described above, the present invention is capable of expanding the fuel cut region to the low rotational speed side without causing torque shock in an engine fuel control device that performs deceleration fuel cut. As a result, on the low rotation speed side,
It is possible to improve fuel efficiency, exhaust purification performance, etc.

[Brief explanation of the drawing]

FIG. 1 is an overall system diagram showing one embodiment of the present invention. FIG. 2 is a graph schematically showing a control example of the present invention. FIG. 3 is a flowchart showing a control example of the present invention. FIG. 4 is an overall configuration diagram of the present invention. FIG. 5 is a graph schematically showing an example of conventional control. l: Engine body 25: Throttle valve 27: Fuel injection valve 31: Control unit 32: Idle switch 34: Sensor No. figure

Claims (1)

[Claims] (1) A fuel supply means for supplying fuel to the engine, a valve opening detection means for detecting the opening of a throttle valve, a rotation speed detection means for detecting the engine rotational speed, and a valve opening detection means for detecting the opening of the throttle valve. a fuel cut means that controls the fuel supply means to cut off the fuel when the valve opening is below a predetermined opening degree and the engine speed is equal to or higher than the fuel cut speed; and a return lower than the fuel cut speed. a first return means for restoring the fuel supply when the rotational speed reaches the rotational speed; and a first return means that returns the fuel supply when the rotational speed reaches the rotational speed; At the same time, once the valve opening of the throttle valve is operated in the opening direction beyond a predetermined valve opening, the fuel supply is restored and the restoration of the fuel supply is maintained as long as the rotational speed does not exceed the fuel cut rotation speed. A fuel control device for an engine, comprising: a second return means for returning the engine.