JP2000282922A - Fuel supply control device of otto cycle engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve drivability of an Otto cycle engine making a fuel cut in the deceleration operation. SOLUTION: An actuator for a fuel cut valve 4 installed in a fuel supply passage 2 is configured on a pneumatic system working with the differential pressure with the atmospheric pressure. A main three-way valve 7 is installed in a main control passage 6 leading from the supply source of a working air to the actuator, while an aux. three-way valve 11 is installed in an aux. control passage 10 leading from a third port of the main three-way valve 7 to the atmosphere. The main 7 and aux. three-way valves 11 are switched over under control according to the engine operating condition by connecting the third port of the aux. valve 11 to the atmosphere via an auxiliary passage 12 fitted with an orifice 13 so as to avoid the sense of passing or lagging after actuation of the fuel cut.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel supply control device for an Otto-cycle engine, and more particularly to a time lag at the time of re-acceleration while preventing a feeling of return at the time of a supply return after a fuel cut operation performed during a deceleration operation of the engine. The present invention relates to a fuel supply control device that is effective in preventing the occurrence of a fuel supply.

[0002]

2. Description of the Related Art In an Otto cycle engine, for example, a CNG engine for a vehicle, in which fuel cut is performed during deceleration operation to improve fuel efficiency, for example, as shown in FIG.
A fuel cut valve 4 is provided in a fuel supply passage 3 leading to the intake passage 2 formed in the main body. , And the third port of the three-way valve 7 is connected to the atmosphere via the atmosphere passage 8. 9 is a driver of the three-way valve 7.

When it is detected that a vehicle (not shown) is being decelerated, the driving section of the fuel cut valve 4 is connected to the vacuum tank 5 via the three-way valve 7 to close the fuel cut valve 4. It was operated to cut fuel and improve fuel economy. When the engine speed drops to a predetermined value and during re-acceleration from a deceleration state, the three-way valve 7 is switched to introduce air into the drive unit of the fuel cut valve 4, whereby the fuel cut valve 4 is turned on. Was opened to return the fuel supply.

[0004] In such a conventional fuel supply control device, the fuel cut valve 4 is opened when the fuel supply is restored after the fuel cut operation, and an amount of fuel corresponding to the load at that time is supplied. As shown by the solid line, the deceleration becomes smaller with the return of the fuel supply, and a feeling of falling off occurs. Note that, in FIG. 8, the broken line indicates the characteristics when the re-acceleration operation is performed during the deceleration operation.

Incidentally, in order to eliminate the feeling of slippage during the deceleration operation as described above, an orifice (not shown) may be provided in the atmosphere passage 8 to extend the valve opening return time of the fuel cut valve 4. However, in this case, since the valve-opening return time at the time of re-acceleration also becomes long, there is a disadvantage that a time lag occurs at the time of re-acceleration, as shown by a two-dot chain line, which causes a feeling of looseness.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to improve the drivability of an Otto cycle engine that performs a fuel cut during a deceleration operation.

[0007]

According to the present invention, an actuator of a fuel cut valve provided in a fuel supply passage is constituted by a pneumatic actuator which operates at a pressure difference from the atmospheric pressure. In addition, a main three-way valve is interposed in a main control passage from a supply source of working air to the actuator, and a sub-three-way valve is interposed in a sub control passage from a third port of the main three-way valve to the atmosphere. . And a control unit for connecting the third port of the sub-three-way valve to the atmosphere via an auxiliary passage provided with an orifice, and for controlling switching of the main and sub-three-way valves in response to an operating state of the engine. Features.

In the invention according to claim 2, the actuator of the fuel cut valve is constituted by a duty solenoid, while the opening of the fuel cut valve is varied via the duty solenoid in response to the operating state of the engine. A control unit for controlling is provided.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram of a main part showing an embodiment in which a fuel supply control device for an Otto cycle engine according to claim 1 is applied to a CNG engine. Parts having the same functions as those of the conventional example shown in FIG. 7 are denoted by the same reference numerals, and detailed description thereof will be omitted.

In FIG. 1, a fuel cut valve 4 is provided in a fuel supply passage 3 extending from a fuel tank (not shown) to an intake passage 2 formed in a mixer 1 of the engine. The actuator constituting the drive unit of the fuel cut valve 4 is constituted by a pneumatic actuator, and a main control passage 6 connecting the pressure chamber and the vacuum tank 5 is provided with a main three-way valve 7 constituted by an electromagnetic valve. ing.

An auxiliary three-way valve 11 composed of a solenoid valve is interposed in a sub-control passage 10 from the third port of the main three-way valve 7 to the atmosphere, and the third port of the sub-three-way valve 11 is opened to the atmosphere. An orifice 13 is interposed in the auxiliary passage 12. By providing a control unit 15 connected to a sensor group 14 for outputting signals based on various driving information such as vehicle speed, throttle opening and engine speed as control means for the main and auxiliary three-way valves 7 and 11,
In response to the operating state of the engine, the main and auxiliary three-way valves 7, 1
1 is switched. 16 is a driver of the sub three-way valve, and 18 is a throttle valve.

In the fuel supply control device for an Otto cycle engine having the above-described configuration, when the engine is operated in a normal state, the control unit 1
5 does not output a fuel cut signal, and the main three-way valve 7
F is activated. Therefore, in this state, the pressure chamber of the fuel cut valve 4 is connected to the sub control passage 10 via the main control passage 6. Since the atmospheric pressure is introduced into the sub control passage 10 through the sub three-way valve 11, the fuel cut valve 4 is kept open, and the fuel in the fuel tank (not shown) is
Is introduced into the intake passage 2 formed at

On the other hand, when the vehicle is decelerated while the engine speed is higher than a predetermined value, a fuel cut signal is supplied from the control unit 15 to the main three-way valve 7. Then, the main three-way valve 7, which previously connected the sub control passage 10 to the main control passage 6, is turned on. Therefore, the main control passage 6, which has been opened to the atmosphere, is switched to the vacuum tank 5, and a negative pressure is introduced into the pressure chamber of the fuel cut valve 4, so that the fuel cut valve 4 is closed to supply fuel. Interrupt.

When the engine speed decreases to a predetermined value as the vehicle speed decreases, the main three-way valve 7 is returned to the OFF state because the fuel cut signal is no longer output. When the accelerator pedal is still released in anticipation of a decrease in vehicle speed, the re-acceleration signal is not supplied from the control unit 15 to the sub three-way valve 13, so that the sub control passage 10 is provided with an auxiliary orifice 13 It is opened to the atmosphere via the passage 12.

Therefore, when the accelerator pedal is kept released, the pressure in the pressure chamber of the fuel cut valve 4 is gradually returned to the atmospheric pressure in synchronization with the stop of the fuel cut signal. The cut valve 4 is gradually opened and returned.
Therefore, the return of the fuel supply after the fuel cut operation is gradually performed, and the sense of deceleration is prevented.

On the other hand, when the accelerator pedal is depressed during the deceleration operation, the control unit 15 outputs a re-acceleration signal to the sub three-way valve 11. Then, the sub three-way valve 12 disconnects the auxiliary passage 12 from the sub control passage 10 and directly opens the sub control passage 10 to the atmosphere, so that the pressure in the main control passage 6 is instantaneously returned to the atmospheric pressure. Accordingly, in this case, the pressure in the pressure chamber of the fuel cut valve 4 is immediately returned to the atmospheric pressure, and the fuel cut valve 4 is rapidly opened and returned. As a result, the supply of fuel is restarted in synchronization with the depression of the accelerator pedal. Is done.

[0017] Therefore, even in the fuel cut operation state accompanying the deceleration operation, when the accelerator pedal is depressed, the supply of fuel is restarted without a time lag, and a feeling of wobble at the time of re-acceleration is avoided. Is done. Incidentally, the fuel supply amount at the time of re-acceleration is set based on the throttle opening, the engine speed, the vehicle speed, and the like supplied from the sensor group 14.

In the above embodiment, the main three-way valve 7
And the sub three-way valve 11 are formed as separate parts, but if these three-way valves 7 and 11 are integrated, the number of parts can be reduced. In the embodiment, the present invention is applied to a vehicle engine using CNG as a fuel. However, the present invention can be applied to a gasoline engine provided with a carburetor instead of a mixer. Further, in the embodiment, the negative pressure is used as the driving source of the fuel cut valve, but an air pressure higher than the atmospheric pressure can be used as the driving source.

FIG. 3 is a schematic diagram of a main part showing an embodiment in which the fuel supply control device for an Otto cycle engine according to the second aspect is applied to a CNG engine. In the present embodiment, the actuator constituting the drive unit of the fuel cut valve 4 is constituted by a duty solenoid. The control signal output from the control unit 15 connected to the sensor group 14 that outputs various signals related to the vehicle speed, the throttle opening, the state of the clutch and gear, the engine speed, the auxiliary brake signal, and the like is output to the duty solenoid. By connecting to the driver 17, the opening of the fuel cut valve 4 is optimally controlled in response to the output signal of the control unit 15.

The control unit 15 determines the operating state of the engine based on various signals supplied from the sensor group. That is, when it is determined based on the output signal of the sensor group 14 that the engine is operating in the normal state, the duty value of the fuel cut signal supplied from the control unit 15 to the driver 17 is set to 0%. The fuel cut valve 4 is kept fully open and does not perform fuel cut.

If it is determined based on the output signal of the sensor group 14 that the engine is being decelerated, the duty ratio of the fuel cut signal supplied from the control unit 15 to the driver 17 is set to 100%. ,
The fuel cut valve 4 is fully closed and the supply of fuel is interrupted.
When the engine speed reaches a predetermined value as the vehicle speed decelerates, and when re-acceleration during deceleration, the duty value of the fuel cut signal is returned to 0% and fuel supply is restored.

Here, it is determined whether or not the operation is deceleration.
For example, it is performed according to the procedure shown in FIG. That is, it is determined in step S1 whether both the clutch and the gear are ON. When it is detected in step S1 that both the clutch and the gear are ON, the process proceeds to step S2 to determine whether or not the vehicle speed V is, for example, 10 km / h or more.

In step S2, the vehicle speed V is, for example, 10
If it is detected that the speed is equal to or higher than Km / h, the process proceeds to step S
3 to determine whether or not the throttle opening α is 0 °. If the throttle opening α is 0 °, the process proceeds to step S4.
Then, it is determined whether or not the engine speed N is 1000 rpm or more. And the engine speed N is 1
Only when the rotation speed is 000 rpm or more, the process proceeds to step S5, and the duty control of the fuel cut valve 4 is started.

When it is detected in step S1 that at least one of the clutch and the gear is OFF, the throttle opening α is set to 0 ° in step S2.
Is not detected, and when the engine speed N is lower than 1000 rpm in step S4, there is no need to perform a fuel cut, so that duty control is not performed, and the process returns to START START to perform deceleration operation. Repeat the determination of whether or not.

The duty control of the fuel cut signal in step S5 is performed, for example, according to the procedure shown in FIG. First, it is determined in step S11 whether the clutch and the gear are both ON. If the result of this determination is that both the clutch and the gear are ON, the flow proceeds to step S12 to determine whether the vehicle speed V is, for example, 10 km / h or more.

In step S12, if the vehicle speed V is 1
When it is detected that the throttle opening is equal to or more than 0 km / h, the process proceeds to step S13 to determine whether or not the throttle opening α is 0 °. When the throttle opening α is 0 °, the process proceeds to step S14. The duty value of the fuel cut signal is read from a memory map (not shown) and output to the driver 17 of the fuel cut valve 4.

The duty value stored in the memory map in advance is set such that the duty value increases as the engine speed N increases, as shown in Table 1, for example.

[0028]

[Table 1]

Therefore, when the engine speed N is higher than 1000 rpm in spite of the deceleration operation, the duty value 100% is read from the memory map, and the fuel cut valve 4 is maintained in the fully closed state. . However, when the engine speed N decreases to, for example, 940 rpm, the read duty value becomes 90%. Similarly, when the engine speed N decreases to 630 rpm, the read duty value becomes 10%.

The engine speed N is set at 600 rpm.
When the engine speed N is lower, the duty value read from the memory map decreases as the engine speed N decreases, such that the duty value becomes 0%.
Finish the fuel cut gradually. Therefore, the fuel supply is gradually returned after the fuel cut operation, so that a feeling of dropout accompanying the end of the fuel cut is avoided.

If it is detected in step S11 that either the clutch or the gear is OFF, in step S12 the vehicle speed V becomes 10 Km / h.
If it is detected in step S13 that the throttle opening is not 0 °,
In any case, it is determined that there is no deceleration operation with fuel cut, and the process proceeds to step S15 to exit duty control.

On the other hand, the re-acceleration determination during the deceleration operation is performed based on, for example, the procedure shown in FIG. First, in step S21, the duty of the fuel cut valve 4 is set to 100%.
(Fully closed) or not, and the duty is 100%
Only when is the process proceeds to step S21, where it is determined whether or not the throttle opening α is equal to or greater than 5 °.

If the throttle opening α is 5 ° or more, the routine proceeds to step S23, where both the clutch and the gear are set to O.
It is determined whether or not the value is N, and when both are ON, the process proceeds to step S24, the duty of the fuel cut valve 4 is set to 0%, and the fuel cut valve is fully opened, thereby returning the fuel supply. .

If it is determined in step S21 that the duty is not 100%, the flow proceeds to step S22.
When it is detected that the throttle opening α is not equal to or more than 5 ° and when it is detected in step S23 that both the clutch and the gear are not in the ON state, it is determined that the vehicle is not re-accelerated, and the process returns to START START. The determination as to whether or not there is is made repeatedly.

The throttle valve 18 provided in the mixer 1
Is variably controlled in response to the amount of depression of an accelerator pedal (not shown) in any of the embodiments. However, there is no need for the connecting means of both to be mechanical means, and the depression of the accelerator pedal is not required. An accelerator opening sensor for outputting a signal responsive to the amount of the throttle valve, and, for example, a stepping motor provided as driving means for the throttle valve, are connected directly or indirectly to connect the throttle valve 18 to the accelerator pedal. An (electronic) linking mechanism may be employed, and the procedure for determining the deceleration operation, the setting of the duty value of the fuel cut valve 4, and the procedure for determining the re-acceleration are not limited to those illustrated.

[0036]

As is apparent from the above description, claim 1
In the invention according to the invention, the opening speed of the fuel cut valve at the time of the return of the fuel supply after the fuel cut operation can be changed according to the operating situation at that time, so that it is possible to prevent the feeling of falling out immediately after the end of the fuel cut. Can be done,
The drivability of the Otto cycle engine is improved in order to prevent a time lag during re-acceleration from deceleration operation.

Further, since the actuator of the fuel cut valve is constituted by a pneumatic actuator, the intended purpose can be achieved only by providing an orifice and switching the main and auxiliary three-way valves by a simple control circuit. Can be achieved. Therefore, there is no need to provide expensive and complicated arithmetic circuits and the like, and an increase in cost required for improving drivability is suppressed.

On the other hand, in the invention according to claim 2, since the duty of the opening of the fuel cut valve is controlled in response to the operating state of the engine, the opening of the fuel cut valve is optimally controlled. Since the reacceleration responsiveness can be increased while avoiding the feeling of coming off when returning to the fuel supply, the drivability of the Otto cycle engine is greatly improved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a main part showing an embodiment in which a fuel supply control device for an Otto cycle engine according to the present invention is applied to a CNG engine.

FIG. 2 is a characteristic diagram of vehicle speed showing a change state from a fuel cut according to the embodiment shown in FIG. 1;

FIG. 3 is a schematic configuration diagram of a main part showing another embodiment in which the fuel supply control device for the Otto cycle engine according to the present invention is applied to a CNG engine.

FIG. 4 is a flowchart illustrating a procedure for determining a deceleration operation according to the embodiment shown in FIG. 3;

FIG. 5 is a flowchart illustrating a setting order of duty values of a fuel cut valve according to the embodiment shown in FIG. 3;

FIG. 6 is a flowchart illustrating a procedure for determining re-acceleration according to the embodiment shown in FIG. 3;

FIG. 7 is a schematic configuration diagram of a main part showing a conventional example of a fuel supply control device for an Otto cycle engine.

FIG. 8 is a characteristic diagram of vehicle speed showing a state of change from fuel cut according to the embodiment shown in FIG. 7;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 mixer 2 intake passage 3 fuel supply passage 4 fuel cut valve 5 vacuum tank 6 main control passage 7 main three-way valve 9 driver 10 sub-control passage 11 sub-three-way valve 12 auxiliary passage 13 orifice 14 sensor group 15 control unit 16 driver 17 driver 18 Throttle valve

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3G092 AA01 AB08 BB01 BB10 CB08 DE04S DE11S DF03 DF09 DG06 DG09 EA09 EA11 EA12 EA16 EA22 EA28 EA29 EB00 EB08 EC08 GA12 GA13 HA06Z HB01X HE01Z HF08 HF08 HF08 JA11 KA15 KA16 KA27 LB00 LC01 LC07 LC10 MA25 NA06 NA08 NB11 ND41 NE01 NE03 NE17 PA11Z PE01Z PF01Z PF03Z PF05Z PF06Z PF07Z

Claims (2)

[Claims] 1. An Otto cycle engine in which a fuel cut valve provided in a fuel supply passage is closed when a deceleration operation of the engine is performed to perform a fuel cut, and an actuator of the fuel cut valve is provided with a pressure difference from an atmospheric pressure. The main three-way valve is interposed in the main control passage from the supply source of the working air to the actuator, while the sub-control passage from the third port of the main three-way valve to the atmosphere is provided in the sub-control passage. A control for interposing a three-way valve, connecting the third port of the sub-three-way valve to the atmosphere via an auxiliary passage having an orifice, and switching and controlling the main and sub-three-way valves in response to an operating state of the engine A fuel supply control device for an Otto cycle engine, comprising a unit. 2. An Otto cycle engine in which a fuel cut valve provided in a fuel supply passage is closed during a deceleration operation of the engine to perform fuel cut, wherein an actuator of the fuel cut valve is constituted by a duty solenoid. A control unit for variably controlling an opening of a fuel cut valve via the duty solenoid in response to an operating state of the engine.