JP3128667B2 - Engine fuel control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel control device for an engine, and more particularly to a fuel control device for an engine having means for stopping fuel supply during deceleration.

[0002]

2. Description of the Related Art In an engine for an automobile or the like, it has been conventionally practiced to stop fuel supply when the engine is decelerated to improve fuel efficiency and emission. In this case, the fuel is stopped under the condition that the throttle valve is fully closed and the engine speed is, for example, 1500 rpm or more. When the engine speed falls below, for example, 700 rpm, the fuel is stopped. And the return rotation speed are usually set with hysteresis.

In order to sufficiently achieve the objectives of improving fuel efficiency and emission, it is necessary to set the fuel stop rotation speed at the time of deceleration as low as possible so that the fuel can be stopped even at a low engine speed. In addition, it is necessary to set the fuel return rotation speed as low as possible so that the fuel stop period becomes longer.However, if the fuel stop rotation speed is reduced or the fuel return rotation speed is reduced, the clutch When the vehicle is depressed or the transmission is set to neutral, a rapid drop in engine rotation due to the loss of power transmission from the vehicle cannot be covered, and as a result, engine stalls are likely to occur. Therefore, as described in Japanese Patent Publication No. 63-16576, for example, when the clutch is disengaged or becomes neutral, the fuel stop rotation speed is made higher or faster than at the time of gear-in so that the fuel is not stopped. Conventionally, it has been proposed to increase the return rotation speed as compared to at the time of gear-in or the like so that the fuel is returned.

[0004]

If control is performed to increase the fuel return rotation speed when the clutch is off or neutral, for example, if the clutch is depressed or the transmission is set to neutral, the speed is reduced as compared to when the gear is engaged. It is difficult to satisfy the execution condition of the fuel stop at the time, and even if the fuel stop at the time of deceleration is executed once, the fuel is returned earlier so that the engine stall can be prevented, but such control is performed. Also, even when the clutch is turned off or neutral for a very short time, such as during a normal shift change, the set speed is increased uniformly, so there is no worry about engine stall due to short clutch off or neutral. Despite the absence, the fuel stop during deceleration was released due to a temporary drop in rotation. There is that Mau, which hinders improvement of fuel efficiency. Also, when returning to fuel after a long deceleration fuel stop, fuel is newly attached to the cylinder wall surface, causing the air-fuel ratio of the air-fuel mixture to shift to the lean side, deteriorating the combustibility. If the fuel is restored each time the clutch is turned off or neutral, the exhaust gas purification performance will deteriorate.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and is intended to prevent clutch stall due to fuel stop at deceleration or engine stall at neutral, and to prevent clutch stall or neutral for a short time at shift change. An object is to achieve both fuel efficiency and prevention of deterioration of exhaust purification performance.

[0006]

FIG. 1 shows a configuration of an engine fuel control apparatus according to the present invention, in which a deceleration detecting means for detecting a deceleration state of the engine and an engine for detecting an engine speed. The engine speed is equal to or higher than the first set speed, and the engine is in a decelerating state by receiving the detection signal from the rotation speed detection means and the deceleration detection means, and receiving the output from the engine rotation speed detection means. The fuel supply control device controls the fuel supply device so as to stop the fuel supply to the engine as an execution condition, a deceleration-time fuel stop control means, a detection signal of the deceleration detection means, and an output of the engine speed detection means, Once the execution condition is satisfied, when the engine speed falls below the second set speed that is lower than the first set speed, the fuel recovery device controls the fuel supply device to return the fuel supply. Receiving control means, and the transmission system coupling releasing detecting means for detecting a decoupling of the power transmission system for transmitting the power of the engine, the output of the transmission system connecting cancel detection means,
An engine fuel comprising a set speed changing means for increasing at least one of the first set speed and the second set speed when the power transmission system is in the disconnected state and at least one of the first set speed and the second set speed compared to when the power transmission system is in the connected state. The control device receives the output of the transmission system disconnection detecting means, detects the duration of disconnection of the power transmission system, and detects this duration when a shift change is required.
The apparatus is characterized in that a set speed change limiting means is provided for limiting the change of the speed by the set speed changing means within a predetermined time corresponding to the predetermined time .

[0007]

For example, when the deceleration state of the engine is detected based on the output of the throttle sensor indicating that the throttle valve is fully closed, and the engine speed is equal to or higher than the first set speed, the deceleration-time fuel stopping means operates the fuel injection valve and the like. The fuel supply device is controlled to stop the fuel supply to the engine, and thereafter, the fuel supply is restored when the engine speed drops and falls below the second set speed. At this time, when the clutch of the power transmission system is depressed or the transmission is set to neutral, one of the first set speed as the fuel stop speed and the second set speed as the fuel return speed is changed to one. The set number of revolutions is changed to be higher. Also,
The time required for a shift change is the duration of the state in which the clutch is depressed or neutral as described above.
During a considerable period of time or less , the change of the set rotation speed is prohibited or restricted.

[0008]

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

FIG . 2 is an overall system diagram of one embodiment of the present invention. In the figure, reference numeral 1 denotes an engine. The engine 1 is a four-cycle gasoline engine that performs suction, compression, explosion, and exhaust by reciprocating a piston 3 in a cylinder 2. A cylinder head 4 has a combustion chamber 5 between the cylinder 3 and the piston 3. Inlet port 6 to open
And an exhaust port 7 are formed.
There is provided an intake valve 8 and an exhaust valve 9 for opening and closing.
Although not shown, a spark plug is inserted into the combustion chamber 5 from the cylinder head 4 side.

[0010] intake manifold 10 of the engine 1 has one end communicated with the air cleaner 11 and the other end communicating with the intake port 6. This intake passage 10 is provided with a surge tank 1 in the middle of the passage.
A throttle valve 13 is provided upstream of the surge tank 12, and a fuel injection valve 14 is inserted downstream of the surge tank 12 toward the intake port 6. An air flow sensor 15 for detecting the amount of intake air is provided immediately downstream of the air cleaner 11 in the intake passage 10.

[0011] The exhaust port 7 of the engine 1 exhaust passage 1
The exhaust gas passage 16 is provided with a catalytic converter 17 downstream thereof. An O ₂ sensor 18 for detecting the oxygen concentration in the exhaust gas is provided at a position upstream of the catalytic converter 17 in the exhaust passage 16.

In FIG . 2, reference numeral 19 denotes a control unit constituted by using a microcomputer.
The control of the fuel injection valve 14 is performed by the control unit 19.
Done by Therefore, the control unit 1
9, an engine rotation signal is input from a rotation sensor incorporated in the ignition system distributor 20, an intake air amount signal is input from the air flow sensor 15, and an engine water temperature is input from a water temperature sensor 21 installed in the engine 1. A signal is input from the O ₂ sensor 18 as an oxygen concentration signal. Also, the control unit 19
An output signal of a throttle sensor 22 for detecting an opening degree of the throttle valve 13 is input to the clutch switch 2 for detecting a depressed state of a clutch (not shown).
3 is input. Control unit 19
Then, the fuel injection amount is calculated based on the input information. Then, an injection signal corresponding to the calculated fuel injection amount is output, whereby the fuel injection valve 14 is driven to open and close.

In the control of the fuel injection amount, first, a basic injection amount is calculated based on the engine speed and the intake air amount, and various correction amounts according to the engine water temperature and the like are calculated. Further, in a predetermined feedback region, O
A feedback correction amount is calculated according to the difference between the air-fuel ratio obtained from the output of the _two sensors 18 and the target air-fuel ratio. The final injection amount is calculated by adding these correction amounts to the basic injection amount, and an injection pulse having a pulse width corresponding to the calculated final injection amount is output to the fuel injection valve 14. Also,
At the time of engine deceleration, the fuel injection is stopped on condition that the engine speed is once at or above a predetermined fuel stop speed, and then the fuel stop is released when the engine speed decreases and the fuel return speed is cut off, Injection is resumed. Here, the fuel stop rotation speed is, for example, 1500 rpm. On the other hand, the fuel return rotation speed is always 700 rpm obtained by subtracting, for example, 800 rpm as the His rotation from the stop rotation speed.
pm. When the clutch switch is turned on when the clutch is turned off, if the clutch-off continuation time is short, for example, within a normal shift change required time (for example, 1 second), the fuel return rotation speed also changes the hiss rotation to, for example, 800 rpm. Is set to 700 rpm, but when the clutch-off duration is longer than that, the fuel return rotation speed is set to 90 rpm with the hiss rotation set to, for example, 600 rpm.
It is set to 0 rpm.

FIG . 3 shows a characteristic change of the fuel stop determination rotation flag (Xncut) when the fuel return rotation speed at the time of clutch off is changed by the clutch off duration as described above. Here, the solid line indicates the case where the clutch off duration exceeds 1 second, and the broken line indicates the case where the clutch off duration is less than 1 second at the time of a normal shift change or the like. The fuel stop determination rotation flag becomes 1 when the engine rotation speed reaches the fuel stop rotation speed during deceleration, and becomes 0 when the return rotation speed is cut off. In the case of this embodiment, when the engine speed reaches 1500 rpm, the flag becomes 1, and in this state, when the throttle valve 13 is fully closed and the fuel stop execution condition is satisfied, the fuel injection is stopped. If the clutch is depressed during this time, if the clutch-off continuation time is within one second, the flag is kept at 1 until the engine speed drops to 700 rpm as shown by the broken line in FIG. By the way, for the first time, the flag is set to 0 and the fuel is returned. If the clutch-off duration exceeds 1 second, the flag is set to 0 at 900 rpm and the fuel is returned, as shown by the solid line.

The time chart of FIG . 4 shows the control characteristics obtained by setting the fuel return rotation speed to be lower when the clutch-off duration is short than when the clutch-off duration is long, as described above. In the conventional control in which the fuel return rotational speed is uniformly increased when the clutch is off, the fuel return rotational speed is set to 700 rpm when the gear is engaged, but is unconditionally increased to 900 rpm when the clutch switch is turned on. When the engine speed falls below 900 rpm, the fuel stop determination rotation flag immediately becomes 0 as shown by the broken line in the figure, and the fuel returns. On the other hand, in the case of the above embodiment, the clutch switch is turned on.
If the time is within one second, the fuel return rotation speed is kept at 700 rpm, which is the same as when the gear is engaged, so the flag becomes 0 and the fuel returns only when the engine rotation speed drops below 700.

Next, specifically described a procedure for the fuel stop determination rotation flag set based on the flowchart of FIG. Note that S1 to S7 indicate each step of the flowchart.

In this flowchart, when starting, Ne (engine speed) is first read in S1, and S1 is read.
2 and Ne is ncut (fuel stop rotation speed (= 15
00 rpm)).

If the determination in S2 is NO (Ne <ncut), the process returns. In addition, YES (Ne
≧ ncut), the process proceeds to S3, and Xncut
(Fuel stop determination rotation flag) is set to 1. And S4
To see if Cgrind (gear-in delay counter) is 0. Here, Cgrind is a counter that is set when the gear is switched from gear-in to clutch-off, and reset when clutch-off lasts for one second.

When Cgrind = 0 (YES) in S4, it means that the clutch has been off for more than one second. In this case, in step S5, KSNCT is changed from ncut.
M (His rotation speed of clutch off setting (= 600 rpm)
m)) is subtracted and the return determination is made using the value (900 rpm) as the fuel return rotation speed. If ne <ncut−KSNCTM, the routine proceeds to S6, where Xncut is set to 0, and ne ≧ nc.
If it is ut-KSNCTM, the process directly returns.

If Cgrind ≠ 0 (NO) in S4, it means that the clutch is off within 1 second. In this case, KSNCTMS (normally set hiss rotation speed (= 800 rpm)) is subtracted from ncut in S7. Value (70
0 rpm) is determined as the fuel return rotation speed,
If e <ncut-KSNCMS, go to S6, set Xncut to 0, and ne ≧ ncut-KSNCMS.
If so, return.

In the above embodiment, the clutch switch signal is used as input information because the transmission is a manual transmission. However, in the case of an automatic transmission, the neutral switch signal is used instead of the clutch switch signal.

In the above embodiment, the fuel stop rotation speed is set to, for example, 1500 rpm.
The pm is a setting when the engine water temperature is 80 ° C. If the engine water temperature changes, the appropriate value of the fuel stop rotation speed changes. For example, when the water temperature is 10 ° C., the fuel stop rotation speed is appropriately about 3000 rpm. Further, the appropriate value of the fuel stop rotation speed is further increased by about 200 rpm when the air conditioner is turned on, for example, and varies depending on the operation state of the brake.

In the above embodiment, control is performed such that only the fuel return rotation speed is increased when the clutch is off or the neutral state continues for a predetermined time or more. In this case, the fuel is rotated in parallel with the fuel return rotation speed. The stop rotation speed may be increased, or only the fuel stop rotation speed may be increased.

[0024]

Since the present invention is constructed as described above, even when the vehicle is decelerating, the execution of the fuel supply stop is suppressed when the clutch is off or in the neutral state, and the recovery from the fuel stop is accelerated to prevent the engine stall. In addition to this, it facilitates stopping the fuel during a short clutch-off or neutral period such as when shifting gears, suppressing fuel return, improving fuel efficiency, and minimizing deterioration of exhaust purification performance due to air-fuel ratio deviation at the time of fuel return. Can be kept to a minimum.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of the present invention.

FIG. 2 is an overall system diagram of an embodiment of the present invention.

FIG. 3 is a characteristic diagram showing a change characteristic of a fuel stop determination rotation flag when a clutch is off in one embodiment of the present invention.

FIG. 4 is a time chart showing control characteristics according to one embodiment of the present invention.

FIG. 5 is a flowchart for executing setting of a fuel stop determination rotation flag of control in one embodiment of the present invention;

[Explanation of symbols]

 1 Engine 14 Fuel Injection Valve 19 Control Unit 20 Distributor 22 Throttle Sensor 23 Clutch Switch

Claims (1)

(57) [Claims] A deceleration detecting means for detecting a deceleration state of the engine; an engine speed detecting means for detecting an engine speed; an output of the engine speed detecting means for receiving a detection signal from the deceleration detecting means. In response, the deceleration fuel stop that controls the fuel supply device to stop the fuel supply to the engine on the condition that the engine speed is equal to or higher than the first set speed and the engine is in a deceleration state Control means, receiving a detection signal of the deceleration detection means,
Further, upon receiving the output of the engine speed detecting means, once the execution condition is satisfied, the fuel supply is restored when the engine speed falls below a second set speed lower than the first set speed. Fuel return control means for controlling the fuel supply device, transmission system disconnection detecting means for detecting disconnection of a power transmission system for transmitting power of the engine,
Upon receiving the output of the transmission system disconnection detecting means, when the power transmission system is in the disconnected state, the first set rotation speed and the second set rotation speed are different from those when the power transmission system is in the connected state. In a fuel control device for an engine having a set speed changing means for increasing at least one of the speeds, an output of the transmission system disconnection detecting means is received, a duration of disconnection of the power transmission system is detected, and the duration is shifted.
An engine fuel control device, further comprising a set speed change limiting means for limiting a change in the speed by the set speed changing means when the time is within a predetermined time corresponding to the required time for the engine.