JPH07166902A - Fuel cut device for engine - Google Patents

Abstract

PURPOSE:To cut fuel in a range as wide as possible by reflecting the intention of a driver during deceleration of a vehicle. CONSTITUTION:A fuel cut device is provided with a means 1 for detecting deceleration timing of a vehicle, a means 2 for detecting whether the down-shift operation of a transmission is executed, and a fuel cut means 4 for stopping fuel feeding to a fuel feeding means 4 directly after the down-shift operation is executed during deceleration of the vehicle. Effectiveness of engine brake is thus improved while fuel consumption is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a fuel cut device for cutting off fuel supply to an engine when a vehicle is decelerated.

[0002]

2. Description of the Related Art In order to improve fuel efficiency and engine braking effect, there is a demand to perform fuel cut in a wide range as much as possible during deceleration of a vehicle.

The fuel cut area of a conventional engine is set according to the throttle opening, the engine speed and the cooling water temperature, as shown in the map of FIG. 8 (Japanese Patent Laid-Open No. 56-50232). JP-A-4-14
3434 publication, reference).

To explain this, in a region where the engine speed is lower than the reference value N ₃ , the fuel cut is not performed and so-called engine stall in which the operation of the engine is stopped is prevented. If the engine speed is in the range of the reference value N ₁ or more and the throttle valve is fully closed, fuel cut is performed.

There is a demand to set the reference value N ₁ low to widen the fuel cut region. However, when the reference value N ₁ is brought close to the reference value N ₃ , the vehicle runs on a downhill while applying engine braking. In this operating state, when the engine speed is higher than the reference value N ₁ , fuel cut is performed and the engine braking effect is strong, but when the engine speed or the reference value N ₃ is eventually reached, fuel supply is restarted and the vehicle is restarted. Is accelerated, and eventually the engine speed reaches the reference value N ₁ , fuel cut is performed, and hunting may occur.

As a countermeasure against this, a reference value N ₂ is set between the reference value N ₁ and the reference value N ₃ , and the throttle valve is changed from the open position to the fully closed position in a region where the engine speed is higher than the reference value N _2. After the transition, the fuel cut will be performed. As a result, for example, if the engine speed when the accelerator pedal is released from the acceleration running or the steady running is the reference value N ₂ or more, the fuel cut is performed,
It is designed to improve fuel efficiency.

[0007]

However, in such a conventional engine fuel cut device, for example, the vehicle is running in the fourth speed gear having a small reduction ratio, and the engine speed is the reference value N _3. In a lower driving state, fuel cut is not performed even if the accelerator pedal is released, and a downshift operation is performed to the second speed gear to activate the engine brake, and the engine speed increases even if the engine speed increases by the gear ratio. If it does not rise above the reference value N ₁ , the fuel cut is still not performed, and there is a problem in that the effect of engine braking is poor.

The present invention focuses on the above-mentioned problems, and an object of the present invention is to perform a fuel cut in a wide range as much as possible while reflecting the driver's intention when the vehicle is decelerated.

[0009]

As shown in FIG. 1, a fuel cut device for an engine according to a first aspect of the present invention includes means 1 for detecting a deceleration time of a vehicle and a downshift operation of a transmission. The detection means 2 and the fuel cut means 3 for stopping the fuel supply of the fuel supply means 4 immediately after the downshift operation is performed during deceleration of the vehicle.

As shown in FIG. 2, an engine fuel cut device for an engine according to a second aspect of the present invention includes means 1 for detecting when the vehicle is decelerating, means 5 for detecting the engine speed, and engine speed when the vehicle is decelerating. Is a reference value NC1 or more, the fuel cut means 6 for stopping the fuel supply of the fuel supply means 4, the means 2 for detecting that the downshift operation of the transmission is performed, and the engine speed during deceleration of the vehicle. The fuel cut means 7 stops the fuel supply of the fuel supply means 4 immediately after the downshift operation is performed in the operating state of the reference value NC2 or more lower than the reference value NC1.

[0011]

According to the first aspect of the present invention, when the downshift operation of the transmission is performed during deceleration of the vehicle, the engine fuel cut device performs the fuel cut in accordance with the driver's intention to enhance the effect of the engine brake. At the same time, fuel consumption can be reduced.

In the engine fuel cut device according to the second aspect of the present invention, the engine speed is the reference value NC when the vehicle is decelerated.
When the downshift operation of the transmission is performed in the operating state in which the fuel cut is performed in one or more operating states, the fuel cut is continuously continued.

When the vehicle is decelerated, the engine speed is the reference value N.
When the engine speed increases to the reference value NC2 or more by performing the downshift operation of the transmission in an operating state in which fuel is being supplied in a lower operating state than C1,
Fuel cut is performed.

[0014]

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

FIG. 3 is a block diagram of a control system of the engine. 10 is a fuel injection valve for supplying fuel to the engine, and 11 is a control unit for controlling the amount of fuel injected from the fuel injection valve 10. is there.

Reference numeral 12 in the drawing denotes an idle switch which is turned on when the throttle valve that adjusts the intake air amount in conjunction with the accelerator pedal is in the fully closed position, and is turned off when it is in the open position.

In the figure, 13 is a sensor for detecting the engine speed Ne, 14 is a sensor for detecting the vehicle speed, and 15 is a sensor for detecting the engine cooling water temperature.

Reference numeral 16 in the drawing denotes a select position switch provided as a sensor for detecting the gear position of the transmission of the vehicle. As a transmission, 1st speed, 2nd speed, 3rd speed, 4th speed,
A manual transmission with five gear positions and five gear positions in which the reduction ratio gradually decreases, or one range, two ranges,
An automatic transmission having three ranges, a D range, and four gear positions in which the reduction ratio gradually decreases is used. Further, instead of the select position switch 16, it is possible to calculate the gear position from the engine speed Ne and the detected value of the vehicle speed.

The control unit 11 inputs these detected values and, based on the map of FIG. 4, performs fuel cut when the throttle valve is fully closed in the region where the engine speed is NC1 or more. In a region where the engine speed is lower than NR, fuel cut is not performed and so-called engine stall in which the operation of the engine is stopped is prevented.

Further, when NC2 is set between NC1 and NR and the throttle valve shifts from the open position to the fully closed position in a region where the engine speed is higher than NC2, fuel cut is performed. Thus, for example, if the engine speed when the accelerator pedal is released from the acceleration running or the steady running is NC2 or more, the fuel cut is performed.

As the gist of the present invention, when the downshift operation is performed during deceleration in a region where the engine speed is higher than NC2, the fuel cut is performed.

The flowchart of FIG. 5 shows a control program executed by the control unit 11 for detecting the downshift operation of the transmission, which is executed every 10 msec.

First, in step 1, the shift value A corresponding to the gear position is detected from the detection signal of the select position switch 16.
Read in. The shift value A is set to 1 in 1st gear in the case of a manual transmission, 2 in 2nd gear, 3 in 3rd gear, 4 in 4th gear, 5 in 5th gear, and 1 in 1 range in an automatic transmission. 2 in 2 ranges,
The range is set to 3 and the D range is set to 4.

Next, in step 2. The current shift value A is subtracted from the previous shift value B, which will be described later, and the subtraction shift value A
From the value of -B, during upshift operation, without shift operation,
It is determined whether the downshift operation is being performed.

When the upshift operation in which the subtraction shift value AB is positive is performed, the process proceeds to step 3 and the downshift flag is set to zero. Then, in step 9, the shift value B
To the current shift value A.

During the downshift operation in which the subtraction shift values AB become negative, the process proceeds to step 4, the downshift flag is set to 1, the timer is cleared, and then step 5 is performed.
Proceed to.

Even when there is no shift operation in which the value of the subtraction shift value AB becomes 0, the process proceeds to step 5 and it is confirmed that the downshift is 1 and the downshift flag is 1, and in step 6, The timer is incremented, and when the timer value reaches 2 seconds in step 4, the process proceeds to step 8 to clear the downshift flag.

Finally, in step 9, the shift value B is changed to the current shift value A.

In this way, the downshift flag is set to 1 for 2 seconds after the downshift operation is performed.
It is supposed to be.

The flow chart of FIG. 6 shows a control program for executing the fuel cut executed in the control unit 11, which is 10 msec.
It is executed every time.

First, On and Of of the idle switch 12
The flag operation is performed according to f. The flag Fid is used to determine whether the idle switch 12 is on or off, and is cleared when the idle switch 12 is off (steps 11 and 19).

The flag Fid2 is an idle switch 12
Changes from Off to On (1)
1, 12, 20).

When the idle switch 12 whose flag Fid is 1 is On, the routine proceeds to step 13, where it is judged whether or not the fuel cut is currently being performed. Flag FFC is 1 during fuel cut,
It becomes 0 during fuel supply.

During the fuel cut, the routine proceeds to step 21, where On and Off of the idle switch 12 are judged.
If the idle switch 12 is Off, the routine proceeds to step 22, the flag FFC is cleared, fuel supply is restarted, and this routine is ended.

When the idle switch 12 is On, the routine proceeds to step 23 to clear the flag Fid2, and then proceeds to step 24 to determine whether the engine speed Ne is lower than the reference value NR. If the engine speed Ne is lower than the reference value NR, clear the flag FFC,
The fuel supply is restarted and this routine ends.

On the other hand, while the fuel is being supplied for which the FFC is judged to be 0 in step 13, the routine proceeds to step 14 where it is judged whether the idle switch 12 is on or off. If the idle switch 12 is Off, the routine proceeds to step 26, where the flag FFC is cleared, fuel supply is restarted, and this routine ends.

If the idle switch 12 is ON, the routine proceeds to step 15, where the engine speed Ne is set to the reference value NC1.
Determine if higher. If the engine speed Ne is higher than the reference value NC1, proceed to step 27, set the flag FFC to 1, clear the flag Fid2,
Continue fuel cut.

When the engine speed Ne is less than the reference value NC1, the routine proceeds to step 16, where it is determined whether the engine speed Ne is higher than the reference value NC2. Engine speed N
When e is equal to or less than the reference value NC2, the routine proceeds to step 28, the flag Fid2 is cleared, and this routine is ended.

When the engine speed Ne is higher than the reference value NC2, the routine proceeds to step 17, where the downshift flag described above is checked. If it is determined that the downshift flag is 1 and the downshift operation of the transmission has just been performed, the routine proceeds to step 29, where the flag FFC is cleared to 1 and the flag Fid2 is cleared to perform fuel cut.

Next, in step 18, the flag Fi
Check d2. When the flag Fid2 is 1 in the operating state in which the idle switch 12 is changed from Off to On, the process proceeds to step 30 and the flag FFC is set to 1
Then, the flag Fid2 is cleared, fuel cut is performed, and this routine is ended.

As a result, as shown in the timing chart of FIG. 7, for example, when the vehicle is decelerating in the D range of the automatic transmission and the engine speed is lower than NR, the accelerator pedal is released and the engine brake is applied. In order to take effect, a downshift operation is performed to the 2 range, after which the engine speed increases by the gear ratio and the engine speed becomes NC.
When the operating condition rises to 2 or more, fuel cut is performed to enhance the effect of engine braking and reduce fuel consumption.

Further, even when the downshift operation of the transmission is performed in an operating state in which the fuel cut is performed in the rotation range where the engine speed is the reference value NC1 or the reference value NC2 or more when the vehicle is decelerated, the fuel cut is performed. Will be continued.

[0043]

As described above, the engine fuel cut device according to the first aspect of the present invention includes means for detecting deceleration of the vehicle, means for detecting the downshift operation of the transmission, and Since the fuel cut means for stopping the fuel supply of the fuel supply means immediately after the downshift operation is performed at the time of deceleration is provided, when the downshift operation of the transmission is performed at the time of deceleration of the vehicle, the driver's intention is reflected. Fuel cut is performed to enhance the effectiveness of engine braking and reduce fuel consumption.

According to a second aspect of the present invention, there is provided an engine fuel cut device for detecting a deceleration of a vehicle, a means for detecting an engine speed, and a driving condition in which the engine speed is a reference value NC1 or more when the vehicle is decelerated. Fuel cut means for stopping the fuel supply of the fuel supply means, means for detecting that a downshift operation of the transmission is performed, and a reference value N at which the engine speed is lower than the reference value NC1 when the vehicle is decelerated.
Since the fuel cut means for stopping the fuel supply of the fuel supply means immediately after the downshift operation is performed in the operating state of C2 or more is provided, the fuel cut is performed when the downshift operation of the transmission is performed during deceleration of the vehicle. The range of rotation that is performed can be lowered from NC1 to NC2, the effect of engine braking can be enhanced, and fuel consumption can be reduced.

[Brief description of drawings]

FIG. 1 is a diagram corresponding to claims of the invention according to claim 1.

FIG. 2 is a diagram corresponding to claims of the invention according to claim 2;

FIG. 3 is a block diagram of a control system showing an embodiment.

FIG. 4 is also a control map.

FIG. 5 is a flowchart showing the same control contents.

FIG. 6 is a flowchart showing the same control contents.

FIG. 7 is a timing chart showing the same control contents.

FIG. 8 is a control map showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vehicle deceleration detection means 2 Downshift operation detection means 3 Fuel cut means 4 Fuel supply means 5 Engine speed detection means 6 Fuel cut means 7 Fuel cut means 10 Fuel injection valve 11 Control unit 12 Idle switch 13 Engine rotation sensor 14 Vehicle speed sensor 15 Water temperature sensor 16 Select position switch

Claims (2)

[Claims] 1. A means for detecting deceleration of a vehicle, a means for detecting that a downshift operation of a transmission is performed, and a fuel supply of a fuel supply means immediately after a downshift operation is performed for deceleration of a vehicle. A fuel cut device for an engine, comprising: a fuel cut means for stopping the engine. 2. A means for detecting when the vehicle is decelerating, a means for detecting an engine speed, and a fuel for stopping the fuel supply of the fuel supply means when the vehicle is decelerating while the engine speed is at or above a reference value NC1. Cutting means, means for detecting that a downshift operation of the transmission is performed, and immediately after the downshift operation is performed in a driving state in which the engine speed is lower than the reference value NC1 and is lower than the reference value NC1 when the vehicle is decelerated. 2. A fuel cut device for an engine according to claim 1, further comprising a fuel cut means for stopping the fuel supply of the fuel supply means.