JPH0612232Y2 - Engine fuel supply - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention supplies fuel to an engine according to its operating state, and when the operating state of the engine satisfies a predetermined condition, the engine is supplied to the engine. The present invention relates to an engine fuel supply device adapted to stop fuel supply.

(Prior Art) As a technology relating to an engine mounted on an automobile or the like, for example, as shown in JP-A-54-148929, when the operating condition of the engine satisfies a predetermined condition, for example, When the throttle valve that is above a predetermined value and is linked to the accelerator pedal is in the fully closed state (idling opening state), fuel supply to the engine is stopped, so-called deceleration fuel cut is performed, and then the engine When the operating condition does not satisfy the predetermined condition, the fuel supply to the engine is restarted, that is, so-called fuel restoration is performed to improve the fuel consumption and reduce the harmful components contained in the exhaust gas. Are known.

In an engine in which the deceleration fuel cut and the subsequent fuel return are performed under the predetermined conditions as described above, at the time of the deceleration fuel cut, the fuel adhering to the inner wall surface of the intake passage is dispersed and the intake passage is There is almost no fuel adhering to the inner wall surface, which is a so-called dry state. When the fuel is restored while the intake passage is dry, the fuel is supplied to the fuel chamber after being attached to the inner wall surface of the intake passage. A fuel supply delay (fuel recovery delay) depending on the dry state is likely to occur.

In addition, in such an engine, the auxiliary loads such as an air conditioner and an alternator, which are operated by the driving force from the engine, are activated, and the external load that the engine bears becomes large. When the vehicle is shifted to the deceleration state, the engine speed drops sharply during deceleration fuel cut.

(Problems to be solved by the invention) In this way, when the external load that the engine bears at the time of deceleration fuel cut is made large and the engine speed sharply drops, and fuel recovery is performed from that state, Since the driving force required for the engine cannot be obtained due to the fuel return delay as described above, despite the fact that the fuel supply was restarted,
Due to the inertia of the engine, the engine speed may not stop decreasing and engine stall may occur. Such an engine stall is likely to occur particularly when the power transmission path from the engine to the drive wheels is in a cutoff state or when the brake pedal is depressed and the vehicle is in a braking state.

In view of such a point, the present invention is designed to perform deceleration fuel cut when the engine operating condition satisfies a predetermined condition, and then perform fuel recovery when the engine does not satisfy the predetermined condition. Fuel recovery of
A fuel supply device for an engine, which is capable of reliably preventing engine stall from occurring without impairing the feeling of deceleration even when the engine is subjected to a large external load. The purpose is to provide.

(Means for Solving the Problems) In order to achieve the above-mentioned object, an engine fuel supply apparatus according to the present invention has an engine fuel supply device having an amount corresponding to its operating state, as shown in the basic configuration of FIG. When the operating condition of the engine satisfies a predetermined condition, the fuel supplying means for supplying the fuel is brought into a fuel supply stopped state, and after the fuel supply stopped state is taken, the operating state of the engine is changed. In addition to the fuel supply control means for keeping the fuel supply state when the predetermined condition is not satisfied, the rotation speed detection means for detecting the rotation speed of the engine, and when the fuel supply means is in the fuel supply stopped state, In a predetermined period including the time when the fuel supply means shifts to the fuel supply state,
When the degree of decrease in the engine speed detected by the engine speed detecting means is small, the external load borne by the engine is reduced to a degree smaller than when the degree of decrease is large, and the engine speed is detected. When the degree of decrease in the engine speed detected by the means is large, an external load reducing means is provided which takes an operating state in which the engine speed is gradually reduced with the decrease in the engine speed.

(Operation) In the fuel supply device for an engine having the above-described configuration, the external load that the engine bears for a predetermined period including the fuel return time after the deceleration fuel cut by the external load reducing means is the engine speed When the degree of decrease is small, it is reduced with a smaller degree than when the degree of decrease is large, and when the degree of decrease in engine speed is large, it is accompanied by a decrease in the engine speed. It is gradually reduced.

Therefore, the feeling of deceleration is not significantly impaired at the time of deceleration fuel cut, and the degree of decrease in the engine speed immediately after the fuel recovery is reduced, so that engine stall is reliably prevented.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 shows an example of a fuel supply system for an engine according to the present invention, together with a main part of an automobile engine equipped with the same.

In FIG. 2, the intake passage 1 is connected via an air cleaner 10.
The flow rate of the intake air introduced into the air flow sensor 11
Detection signal S detected according to the flow rate of the intake air
a is obtained from the air flow sensor 11, and is supplied to the control unit 100 described later. The intake air is metered by the throttle valve 13 provided in the intake passage 12, and the intake valve 1 provided in the engine body E is controlled.
It is led to the combustion chamber 19 via 7. Throttle valve 13
Is adapted to change its opening degree in response to depression of an accelerator pedal (not shown).
Idle switch 18 in relation to the throttle valve 13
Is provided, and when the idle switch 18 is turned on, the control unit 100 then
A detection signal Si indicating that the throttle valve 13 is fully closed is supplied.

Between the air flow sensor 11 and the throttle valve 13 in the intake passage 12, one end of a bypass passage 15 that bypasses the throttle valve 13 and communicates with a surge tank 14 provided in the middle of the intake passage 12, is opened. A flow rate adjusting valve 16 is provided in the bypass passage 15. The flow rate adjusting valve 16 has its valve opening operation amount changed according to the pulse width of the valve opening drive pulse signal Cp supplied from the control unit 100.

Further, a combustion injection valve 25 is provided at a predetermined position in the intake passage 12, and the combustion injection valve 25 opens at a predetermined timing according to the pulse width of the injection drive pulse signal Pc supplied from the control unit 100. The fuel which is valve-operated and pressure-fed from a fuel supply system (not shown) is intermittently injected toward the intake port portion of the intake passage 12 near the combustion chamber 19 to generate a mixture with intake air. . The air-fuel mixture is drawn into the combustion chamber 19, ignited by the spark plug 21 and burned, thereby operating the engine.

The air-fuel mixture burned in the combustion chamber 19 is discharged as exhaust gas to the exhaust passage 23 via the exhaust valve 22.

The rotation speed sensor 2 arranged in association with the crankshaft 26 in the crank mechanism for converting the reciprocating motion of the piston 24 into the rotary motion is the engine speed that operates in this way.
The detection signal Sn detected by 7 is supplied to the control unit 100 according to the engine speed.

The drive force of the crankshaft 26 is transmitted to the drive shaft 29 via the belt 28, and the drive force transmitted to the drive shaft 29 is transmitted via the electromagnetic clutches 31, 32 and 33 to the fluid pump 35 for the power steering device. , Is transmitted to an air pump 36 and an air conditioner 37 that supply a driving force to an actuator provided for controlling the engine or controlling the suspension system, and is also transmitted to an alternator 38. The electromagnetic clutches 31, 32 and 33 are in a disengaged state when the control signals Ca, Cb and Cc are supplied from the control unit 100, respectively, and are in a connected state when the supply of the control signals Ca to Cc from the control unit 100 is stopped. It is supposed to take. When the electromagnetic clutches 31 to 33 are in the connected state, the fluid pump 35, the air pump 36, and the air conditioner 37 are activated, which increases the external load that the engine bears. Further, the alternator 38 is rotated by the driving force from the engine, but its power generation operation is controlled by the regulator 39 attached thereto,
When the alternator 38 is in a power generating state, the external load that the engine bears is significantly increased. When the control signal Cd is supplied from the control unit 100, the regulator 39 stops the power generation operation of the alternator 38 to reduce the external load on the engine. The external load borne by the engine when the fluid pump 35 and the air pump 36 are activated is relatively small, and the engine when the air conditioner 37 and the alternator 38 are activated and generate electricity, respectively. It is assumed that the external load borne by the company is relatively large.

The control unit 100 includes detection signals Sa and Si.
In addition to Sn and Sn, it is necessary to control the engine, which represents the running state of the engine such as the cooling water temperature and the operating state of the engine, the shift position of the transmission attached to the engine body E and the operating state of the brake pedal or clutch pedal. Other detection signals Sx are also supplied.

The control unit 100 obtains a control value D based on the detection signal Sx, forms a valve opening drive pulse signal Cp having a pulse width corresponding to the control value D, and supplies it to the flow rate adjusting valve 16, By changing the valve opening operation amount, the intake air amount of the engine is adjusted to control the actual idle speed to converge to the target idle speed.

The control unit 100 also detects the detection signals Sa,
The fuel injection amount in the fuel injection valve 25 is controlled based on Si, Sn and Sx. At that time, the control unit 100 calculates the basic fuel injection amount Tp based on the intake air amount Q and the engine speed N represented by the detection signals Sa and Sn, respectively, and the detection signal S is calculated as the basic fuel injection amount Tp.
An injection driving pulse signal P having a pulse width corresponding to the calculated fuel injection amount Ti is calculated by adding various corrections according to the operating state of the engine represented by x.
c is formed and is supplied to the fuel injection valve 25. As a result, when the engine is in the normal operating state, the engine is supplied with fuel in an amount corresponding to the operating state.

Furthermore, the control unit 100 detects the detection signal Si
And Sn after the throttle valve 13 is changed from the open state to the fully closed state to shift the engine to the decelerating operation state, until the engine speed N drops below a predetermined value N ₁ , or the throttle valve The supply of the injection drive pulse signal Pc to the fuel injection valve 25 is stopped to perform deceleration fuel cut until 13 is opened, and when the engine speed N becomes less than the value N ₁ , or the throttle valve 13 Is opened, the supply of the injection drive pulse signal Pc to the fuel injection valve 25 is restarted to restore the fuel.

In this way, when the deceleration fuel cut is performed and then the engine speed N becomes less than the value N ₁ to restore the fuel, the control unit 100 reduces the external load on the engine. Control signals Ca to C
c and Cd are formed and supplied to the electromagnetic clutches 31 to 33 and the regulator 39 at the timing as described below.

First, when the control unit 100 detects that the engine is in the deceleration fuel cut state, it calculates the degree of decrease in the engine speed N, and when the degree of decrease is small, that is, when the engine is in the gentle deceleration state. Since the engine stall is unlikely to occur even if the external load that the engine bears is large,
Control signals Ca and Cb only to the electromagnetic clutches 31 and 32
To supply. As a result, the electromagnetic clutches 31 and 32 are turned off, and the transmission of the driving force of the engine to the fluid pump 35 and the air pump 36 is shut off. As a result, when the fluid pump 35 and the air pump 36 are activated. They are brought to a standstill and the external load on the engine is somewhat reduced. Then, the control unit 100 continues the supply of the control signals Ca and Cb to the electromagnetic clutches 31 and 32 even after the engine speed N drops below the value N ₁ and the fuel recovery is performed, and the fuel recovery is performed. As a result, after the engine speed N has reached the minimum value, the engine speed N starts to rise and continues until the degree of increase becomes relatively small. The fluid pump 35 and the air pump 36
Even if the engine is temporarily stopped, the fluid pressure from the accumulator is supplied to the power steering device and the engine control actuator that are driven by the fluid pressure from them, so there is no problem in their operation. To be taken.

On the other hand, when the degree of decrease in the engine speed N is large, that is, when the engine is in a rapid deceleration state, if the external load that the engine bears is large, engine stall may occur. Therefore, for example, as shown in FIG. 3A, the control unit 100 causes the throttle valve 13 to be fully closed and the engine speed N to start decreasing at a deceleration start time t ₁ shown in FIGS. 3B and 3C.
Control signal C to the electromagnetic clutches 31 and 32 as shown in FIG.
Fluid pump 35 and air pump 3 by supplying a and Cb
6 is stopped, and the control signal Cc is supplied to the electromagnetic clutch 33 to operate the air conditioner 37 at the time t ₂ when the engine speed N becomes less than the predetermined value N ₂ , as shown in FIGS. And the regulator 39
To the control signal Cd to control the alternator 38 to stop the power generation operation. At such time, the air conditioner 3
7 is not stopped and the power generation operation of the alternator 38 is not stopped, the engine speed N sharply decreases and engine stall occurs, as indicated by the one-dot chain line in FIG. 3A. However, as described above, the stepwise reduction of the external load due to the decrease in the engine speed N is achieved, so that the feeling of deceleration is not impaired so much, and is indicated by the one-dot chain line in FIG. 3A. As described above, the sudden decrease in the engine speed N is avoided, and the occurrence of engine stall is suppressed. Then, the control unit 100 supplies the control signals Ca and Cb to the electromagnetic clutches 31 and 32 in the same manner as in the slow deceleration state described above, at a value N _{1 at} which the engine speed N restores fuel at time t _3. becomes less than, even after taking the minimum value at time t _4, close to the vicinity of the target idle rotational speed Ni and turned upward, while continuing to time t _6, which becomes its increasing degree is relatively small, the electromagnetic The supply of the control signals Cc and Cd to the clutch 33 and the regulator 39 is continued until the engine speed N reaches a minimum value and then rises to a predetermined value Na or more until a time t ₅ . It should be noted that the value Na is obtained when the engine speed N is equal to or higher than that value even when the fluid pump 35, the air pump 36, and the air conditioner 37 are in the operating state and the alternator 38 is in the power generating state. , Are preselected so that engine stall does not occur.

As described above, in this example, when the deceleration fuel cut and the subsequent fuel return are performed, when the engine is in the gentle deceleration state, the external load that the engine bears is relatively small, and When only the air pump 36 is stopped and the engine is in the rapid deceleration state, the external load that the engine bears is considered to be relatively small while the engine speed N is in the relatively high region of the value N ₂ or more. Fluid pump 35 and air pump 3
After only 6 is stopped and the engine speed N becomes less than the value N ₂ , the air-conditioning device 37 in which the external load on the engine is relatively large in addition to the fluid pump 35 and the air pump 36 And the alternator 38 are brought into a stopped state and a non-power generation state, respectively.
The external load borne by the engine is gradually reduced as the engine speed decreases, and such a state is maintained until after the fuel is restored and the engine speed N starts to increase, so that the feeling of deceleration is impaired. Even if the deceleration fuel cut is started due to a large increase in the external load that the engine bears, a sharp decrease in the engine speed is avoided, and the occurrence of engine stall is reliably prevented.

Control unit 100 for performing control as described above
Will be described with reference to the flow charts of FIG. 4 and FIG. 5 showing an example of a program executed by the microcomputer in such a case, for example.

The flow chart of FIG. 4 shows a basic fuel injection control routine, which is a process 101 after the start.
In step 102, the detection signals Sa, Sn, Si and Sx are fetched, and in the subsequent decision 102, it is determined whether or not the throttle valve 13 is in the fully closed state based on the detection signal Si, and it is determined that the throttle valve 13 is not in the fully closed state. If so, go to process 105.

In the process 105, the basic fuel injection amount Tp is set to T
p = K × Q / N (where K is a constant) is set, and in the subsequent process 106, the detection signal Sa is set.
And Sx, a correction value Cx corresponding to the operating state of the engine is set, and then, in process 107, the fuel supply amount Ti is set by multiplying the basic fuel injection amount Tp and the correction value Cx, and the decision 108 is made. Proceed to.

In the decision 108, it is judged whether or not it is the injection timing based on the crank angle represented by the detection signal Sn. If it is judged that it is not the injection timing, the routine returns to the original state, and if it is judged that it is the injection timing, In the process 110, the injection drive pulse signal Pc having a pulse width corresponding to the fuel supply amount Ti is formed, and the injection drive pulse signal Pc is supplied to the fuel injection valve 25 and the process returns. As a result, an amount of fuel corresponding to the operating state of the engine is injected from the fuel injection valve 25 and supplied to the engine.

On the other hand, when it is determined in the decision 102 that the throttle valve 13 is in the fully closed state, the decision 103 determines whether the engine speed N represented by the detection signal Sn is the value N ₁ or more. Then, when it is determined that the engine speed N is the value N ₁ or more, the process directly returns without passing through the processes 105 to 110. Thereby, deceleration fuel cut is performed. When the decision 103 determines that the engine speed N is less than the value N ₁ , the processes 105 to 110 are executed in the same manner as described above to restore the fuel, and the process returns to the original state.

The program shown in FIG. 5 shows an external load control routine, which takes in the detection signals Sn and Si in the post-start process 120, and determines whether the throttle valve 13 is fully closed based on the detection signal Si in the subsequent decision 121. If it is determined that it is not in the fully closed state, the electromagnetic clutch 3
1 to 33 and control signal Ca to the regulator 39
When the supply of Cd is stopped, the flow returns to the original state, and it is determined that the engine is in the fully closed state, the decision 123 determines whether the engine speed N is a value N ₁ or more, and the engine speed N
Is determined to be equal to or greater than the value N ₁ , the deceleration fuel cut is being performed, and therefore, in the process 124, the engine indicated by the detection signal Sn captured in the process 120 from the engine speed N ′ of the previous time is expressed. The rotation speed N is subtracted to calculate the difference ΔA, and then the decision 125 determines whether or not the difference ΔA is equal to or larger than a predetermined value α.
If it is determined that the difference ΔA is less than the value α, the engine is in a gentle deceleration state, so the process 1
26, the control signals Ca and Cb are sent to the electromagnetic clutch 31.
And 32, and returns. As a result, the fluid pump 35 and the air pump 36 are stopped, and the external load on the engine is reduced.

When the difference ΔA is determined to be the value α or more in the decision 125, the engine is in a rapid deceleration state, so it is determined in the decision 127 whether the engine speed N is the value N ₂ or more, If it is determined that the value is greater than or equal to N ₂ , then in process 126 control signal C
When a and Cb are supplied to the electromagnetic clutches 31 and 32 and returned to the original state, and when it is determined in the decision 127 that the engine speed N is less than the value N ₂ , the external load borne by the engine should be further reduced. , In process 128, the control signals Cc and Cd are supplied to the electromagnetic clutch 33 and the regulator 39, and the process returns.

On the other hand, if the engine speed N is determined to be less than the value N ₁ in the decision 123, the fuel is restored, so the engine speed N represented by the detection signal Sn captured in the process 120 in the decision 130 is expressed. Determines whether the engine speed N'has exceeded the previous engine speed N ', and if it is determined that the engine speed N does not exceed the engine speed N', the process returns to the original and the engine speed N is the engine speed N '. If it is determined that the engine speed N exceeds the number N ', the engine speed N has started to increase, and therefore, the decision 131 determines whether the engine speed N is equal to or higher than the value Na, and the engine speed N is determined. Is determined to be equal to or greater than the value Na, the control signals Cc and Cd are supplied to the electromagnetic clutch 33 and the regulator 39 in the process 132. The stop passes to process 133,
In the decision 131, the engine speed N is the value Na
If it is determined to be less than, the process proceeds to the process 133 without passing through the process 132.

In the process 133, the engine speed N'is subtracted from the engine speed N'to calculate the difference ΔB, and in the subsequent decision 134, it is judged whether or not the difference ΔB is a predetermined value β or less, and the difference ΔB is the value β or less. If it is determined that the engine speed N is close to the target idle speed Ni at which the engine speed N is kept stable, the electromagnetic clutches 31 and 32 of the control signals Ca and Cb in the process 135 are determined.
To the original value, and when the decision 134 determines that the difference ΔB exceeds the value β, the original value is directly returned.

(Effects of the Invention) As is apparent from the above description, according to the engine fuel supply device of the present invention, the external load that the engine bears during the predetermined period including the fuel recovery time point after the deceleration fuel cut is When the degree of decrease in the number of revolutions is small, it is reduced with a smaller degree than when the degree of decrease in the number of revolutions is large, and when the degree of decrease in the number of engine revolutions is large, the decrease in the number of engine revolutions is decreased. As a result, the engine speed is reduced in a stepwise manner, a sharp reduction in the engine speed immediately after fuel recovery is avoided, and the engine stall is reliably prevented without impairing the feeling of deceleration. It is possible to reliably prevent engine stall without impairing the feeling of deceleration.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram showing an engine fuel supply device according to the present invention corresponding to a utility model registration claim, and FIG. 2 is an example of an engine fuel supply device according to the present invention, to which it is applied. Schematic diagram showing the main parts of the engine,
FIG. 3 is a time chart used for explaining the operation of the example shown in FIG. 2, and FIGS. 4 and 5 show the case where a microcomputer is used for the control unit in the example shown in FIG. 7 is a flowchart showing an example of a program executed by such a microcomputer. In the figure, 18 is an idle switch, 25 is a fuel injection valve, 2
7 is a rotation speed sensor, 31, 32 and 33 are electromagnetic clutches, 35 is a fluid pump, 36 is an air pump, 37 is an air conditioner, 38 is an alternator, 39 is a regulator, 10
0 is a control unit.

Claims (1)

[Scope of utility model registration request] 1. A fuel supply means for supplying an amount of fuel to an engine according to an operating state of the engine, and a fuel supply stop state for the fuel supplying means when the operating state of the engine satisfies a predetermined condition. After the fuel supply is stopped, the fuel supply control means keeps the fuel supply when the operating condition of the engine does not satisfy the predetermined condition, and the rotation speed detection for detecting the engine speed. And the fuel supply means is in the fuel supply stop state,
After that, during a predetermined period including the time when the fuel supply means shifts to the fuel supply state, the external load borne by the engine is reduced when the degree of decrease in the engine speed detected by the speed detection means is small. , The degree of decrease is less than that when it is large,
An external load reducing means that takes an operating state in which the engine rotational speed is gradually reduced when the engine rotational speed is detected by the rotational speed detecting means. Engine fuel supply system.