JP3417207B2 - Engine fuel cut 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 cut control device for an engine used for traction control of an automobile.

[0002]

2. Description of the Related Art Recently, not only the engine but also the vehicle is required to have higher fuel economy and drivability. From this viewpoint, the running control of the vehicle is more precisely controlled by using a microcomputer or the like. Is being done. Among them, the vehicle traction control system (TC
S) is receiving attention.

As such a fuel cut control device for an engine, there is one disclosed in, for example, Japanese Patent Application Laid-Open Nos. 4-295146 and 1-227830.

In these devices, the rotational speeds of the driving wheels and the driven wheels are detected to calculate the slip ratio between the driving wheels and the road surface. When the slip ratio is larger than a set value, torque reduction based on the slip ratio is performed. By cutting the fuel of a predetermined number of cylinders of the engine according to the request, when the vehicle enters a slip state due to the generation of excessive driving force, the driving force is quickly reduced to effectively suppress the slip, Improves driving performance.

By the way, when the fuel supplied to a part of the cylinders of the engine is cut, the fresh air from the fuel cut cylinders and the exhaust gas containing the unburned components from the cylinders which have not been cut off the fuel are exhausted to the exhaust system. Depending on the operating conditions of the engine, the temperature of the catalytic converter may rise to an allowable level or higher due to combustion, depending on the operating conditions of the engine, which may lead to deterioration of the catalytic converter.

For this reason, as shown in FIG. 7, by limiting the duration of fuel cut and setting the prohibition time after fuel cut, the temperature of the catalytic converter is maintained even when the fuel cut control is repeated. It is controlled so that it does not rise above the allowable level.

[0007]

However, in such a conventional system, when the vehicle travels on a snowy road, for example, the slip ratio of the drive wheels is large, and the torque reduction request continues intermittently. However, in such a case, even though the torque reduction request continues, fuel cut must be stopped from the viewpoint of catalyst protection, and although the temperature of the catalytic converter can be suppressed below the allowable level, the torque generated by the engine is reduced. It did not decrease and there was still room for improvement in preventing slippage of the drive wheels.

The present invention solves such a problem,
In a fuel cut control device for an engine, it is an object of the present invention to enhance a slip prevention effect while suppressing a temperature rise of a catalytic converter.

[0009]

As shown in FIGS. 8 and 10 , a fuel cut control apparatus for an engine according to a first aspect of the present invention includes a torque down request determining means 101 for determining a torque down request time, and a torque down request determining means 101. Normal fuel cut means 103 for stopping fuel supply to some cylinders whose upper limit is a predetermined number of cylinders when a down request is made, and normal fuel cut mode elapsed time measurement for measuring an elapsed time JFCON after entering a torque down request Means 104, a multi-cylinder fuel cut mode area determination means 105 for determining a multi-cylinder fuel cut mode area in which the normal fuel cut mode elapsed time JFCON is longer than the longest elapsed time FCMAX, and the upper limit value in the multi-cylinder fuel cut mode area. A multi-cylinder fuel that stops fuel supply to a specified number of cylinders that does not fall below And Rukatto means 106, the cylinder fuel supply control means 102 for controlling the fuel supply to each cylinder in response to the determined fuel-cut mode, the normal full
Fuel cut mode elapsed time When the longest JFCON has elapsed
Measure the time elapsed JTFCTI after reaching FCMAX
Multi-cylinder fuel cut mode for measuring elapsed time measuring means
And multi-cylinder fuel cut mode elapsed time JTFCT
It is judged that I becomes more than the longest elapsed time TFCTIM.
Multi-cylinder fuel that ends the multi-cylinder fuel cut mode
-L-cut mode end means .

A fuel cut control device for an engine according to a second aspect of the present invention is the same as that of the invention according to the first aspect.
As shown in, the drive wheel rotation state detecting means 111 for detecting the rotation state of the drive wheels of the vehicle and the slip ratio calculating means 112 for calculating the slip ratio based on the rotation state of the drive wheels.
And a torque down signal output means 113 for outputting a torque down request signal for the engine based on the slip ratio.
And

[0011]

According to a third aspect of the present invention, there is provided an engine fuel cut control system according to the first or second aspect of the present invention, wherein the multi-cylinder fuel cut mode ending means has a multi-cylinder fuel cut mode elapsed time JTFCTI that is a longest elapsed time TFCTIM. If the torque reduction request is exhausted before reaching, the multi-cylinder fuel cut mode is terminated and the multi-cylinder fuel cut mode elapsed time JTFCT
When a torque down request is made before I reaches the longest elapsed time TFCTIM, the multi-cylinder fuel cut mode is restarted.

According to a fourth aspect of the present invention, in the fuel cut control system for an engine according to any one of the first to third aspects, the longest elapsed time TFCTI is set to a high speed / high load range rather than a low speed / low load range of the engine. Set it to be longer.

[0014]

In the engine fuel cut control system according to the first aspect of the present invention, the torque generated by the engine is reduced by cutting off the fuel supply to the predetermined number of cylinders of the engine in the normal fuel cut mode in accordance with the torque down request.

The torque down request is the longest elapsed time set value F.
When CMAX is exceeded, the normal fuel cut mode is switched to the multi-cylinder fuel cut mode, and the number of cylinders whose fuel supply is cut is increased. When the number of cylinders whose fuel supply is cut is increased, the amount of fresh air from the cylinders whose fuel injection is cut increases, so that the temperature of exhaust gas decreases and the number of cylinders whose fuel injection is not cut decreases. The amount of unburned HC is greatly reduced, and the reaction heat generated in the catalytic converter and the like is suppressed.

As described above, even under the operating condition where the fuel cut is prohibited in the conventional system, by increasing the number of cylinders in which the fuel cut is performed and continuing the fuel cut, the reaction heat generated in the catalytic converter and the like is suppressed and the heat resistance is improved. It is possible to reduce the torque generated by the engine while maintaining the property. Also, the multi-cylinder fuel cut mode elapsed time JT
FCTI must be longer than the longest elapsed time TFCTIM.
Judgment can be made and the multi-cylinder fuel cut mode can be terminated.
With this, while ensuring the heat resistance of catalytic converters, etc.
Cylinder fuel cut may be performed longer than necessary
Torque to prevent the driver from feeling excessive deceleration.
You can get a proper answer.

In the engine fuel cut control apparatus according to the present invention, the slip ratio is calculated based on the detected rotation state of the drive wheels, and the engine torque down request signal is output based on the calculated slip ratio. By doing so, the duration of fuel cut is controlled according to the slip ratio of the drive wheels, the operating range in which traction control is performed is expanded, and the slip prevention effect is enhanced while suppressing the temperature rise of the catalytic converter. .

[0018]

[0019] In the fuel cut control apparatus for an engine according to claim 3, once eliminated the torque reduction request during multi-cylinder fuel cut mode, while the multi-cylinder fuel cut mode elapsed time JTFCTI does not exceed the maximum elapsed time set value TFCTIM In addition, when there is a torque reduction request again, the multi-cylinder fuel cut is performed. As a result, for example, when the vehicle travels on a snowy road and the torque down request continues intermittently, the fuel cut in the normal fuel cut mode is performed without much time after the fuel cut in the multi-cylinder fuel cut mode is performed. Is avoided, and the heat resistance of the catalytic converter and the like can be secured.

[0020] In the fuel cut control apparatus for an engine according to claim 4, since the high frequency of requests torque reduction, the exhaust temperature of the engine is at low low speed low load region, the longest elapsed time TFCTI is set relatively short, Normally, the frequency of fuel cut is increased, and the torque can be properly reduced so that the driver does not feel excessive deceleration. On the other hand, in the high-speed and high-load range where the engine exhaust temperature is high, the longest elapsed time TFCTI is set to be relatively long, so the frequency of multi-cylinder fuel cut is increased and the temperature of the catalytic converter etc. rises above the allowable level. Can be prevented.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 20 is an engine mounted on a vehicle. The power of the engine 20 is transmitted from the transmission 27 to the drive wheels 28 via the drive shaft.

The intake air flows from the air cleaner 21 to the intake pipe 2
2. The fuel is supplied to each cylinder from each branch of the intake manifold through the throttle chamber 23, and the fuel is injected toward each intake port by the fuel injector 24 provided for each cylinder and mixed with the intake air.

The air-fuel mixture in the cylinder is ignited and explodes by the discharge of the spark plug. The exhaust gas is exhausted to the outside through the exhaust pipe 25. A catalytic converter 26 is installed in the middle of the exhaust pipe 25 to oxidize HC and CO in the exhaust through a three-way catalyst and reduce NOx.

A throttle valve 30, which is opened and closed by an accelerator pedal, is interposed in the throttle chamber 23. The opening degree of the throttle valve 30 is detected by the throttle sensor 32, the flow rate of the intake air is detected by the air flow meter 34, and the rotation speed of the engine 20 is detected by the crank angle sensor 35. The temperature of the cooling water of the engine 20 is detected by the water temperature sensor 36, and the oxygen concentration in the exhaust gas is detected by the oxygen sensor 37. The catalyst bed temperature of the catalytic converter 26 is detected by the catalyst bed temperature sensor 38.

The rotation speed of the drive wheels 28 of the vehicle is detected by the drive wheel speed sensor 40, and the rotation speed of the driven wheels 41 is detected by the driven wheel speed sensor 42. In this case, the average rotational speeds of the left and right drive wheels 28 and the left and right driven wheels 41 are detected.

The signals from the sensors 32, 34 to 38, 40, 42 are input to the control unit 45 which is a microcomputer.

The control unit 45 controls the fuel injector 2 of the engine 20 based on the input signals.
4 fuel injection control and vehicle traction control.

As shown in FIG. 2, the control unit 45 includes a throttle opening detection section 61 for inputting a detection signal of the throttle sensor 32, an engine speed detection section 62 for inputting a detection signal of the crank angle sensor 35, and An intake air amount detector 63 for inputting a detection signal of the air flow meter 34, an engine speed N and an intake air amount Q detected by the detector.
A basic fuel injection pulse width calculation unit 64 that calculates the basic fuel injection pulse width Tp based on
And a drive circuit 66 that outputs a fuel injection pulse signal to the injector 24.

Fuel injection control is performed by detecting the detected intake air amount Q.
Based on a and the engine speed N, the basic injection amount Tp is calculated as Tp = K · Qa / N (1), where K is a constant, and then the basic injection amount Tp is detected. Tw, throttle opening TVO, oxygen concentration in exhaust gas, etc. are corrected according to the following equation, and the fuel injection amount Ti
Is calculated.

Ti = Tp × (1 + K _TW + K _AS + K _AI + K _ACC + K _DEC ) × K _FC + T _S (2) where K _TW ; water temperature increase correction coefficient K _AS ; start and post-start increase correction coefficient K _AI Post-idle amount increase correction coefficient K _ACC ; acceleration correction coefficient K _DEC ; deceleration correction coefficient K _FC ; fuel cut correction coefficient T _S ; battery voltage correction amount A pulse signal corresponding to the calculated fuel injection amount Ti is supplied to each fuel injector 25. To the fuel injection control.

As shown in FIG. 2, the control unit 45 has a wheel speed detecting section 51 for inputting detection signals of the wheel speed sensors 40 and 42, and a wheel speed for calculating a rotational speed ratio between the driven wheel 41 and the driving wheel 28. A ratio calculation unit 52, a slip ratio calculation unit 53 that calculates the slip ratio of the drive wheels 28 based on the rotation speed ratio of the driven wheels 41 and the drive wheels 28, and a torque reduction request amount of the engine 20 according to the slip ratios. And a torque down control signal output unit 55 that outputs a torque down control signal according to the torque down request amount.

The flowchart of FIG. 3 shows a routine which is processed as a job for calculating the required torque reduction amount when the drive wheels 28 slip, and is executed by the control unit 45 at regular intervals.

Explaining this, first, the driving wheel speed (average value of left and right) V _DW is read in step 1, the driven wheel speed (average value of left and right) V _PW is read in step 2,
In step 3, the slip ratio SL is calculated according to the following equation.

SL = (V _DW −V _PW ) / V _PW (3) When this slip ratio SL is larger than the set value, it is determined that the drive wheels 28 have slipped, and the routine proceeds to step 5. The torque reduction request amount D is set in accordance with the slip ratio SL, and at step 6, the torque reduction request flag TD is set to 1.

On the other hand, when the slip ratio SL is smaller than the set value, it is judged that no slip has occurred on the drive wheels 28, and the routine proceeds to step 7, where the required torque down amount D is set to 0.
And the torque down request flag TD is set to 0 in step 6.

The control unit 45, as shown in FIG.
The fuel cut mode that sets the normal fuel cut mode that stops the fuel supply to some cylinders when a torque down is requested and the multi-cylinder fuel cut mode that stops the fuel supply to the number of cylinders that is larger than the normal fuel cut mode range is set in advance. Is set. Control unit 4
Reference numeral 5 denotes a torque down request cylinder cut number calculation unit 56 that calculates the number of cylinders for which the fuel supply from the injector 24 is cut in this way, and a fuel cut duration time counter unit 5 that calculates the elapsed time after entering each fuel cut mode.
7 and a fuel cut cylinder number determination unit 5 that switches between the normal fuel cut mode and the multi-cylinder fuel cut mode according to the elapsed time after entering each fuel cut mode
8 and a fuel cut availability determination unit 59 for instructing fuel cut so that the operation of the engine 20 is not stopped.

The flow charts of FIGS. 4 and 5 show the drive wheels 2
8 shows a routine that is processed as a job for performing torque down control when a slip occurs, which is executed by the control unit 45 at regular intervals.

Explaining this, first, at step 11, it is judged if there is a torque down request (TD = 1).

When the torque down request flag TD = 1,
In step 12, it is determined whether the normal fuel cut mode is in operation or the multi-cylinder fuel cut mode is in operation.

In normal fuel cut mode (F
If it is determined that M = 0), the process proceeds to step 13 to measure the normal fuel cut mode elapsed time JFCON,
The normal fuel cut mode elapsed time JFCON measured in step 14 is the longest elapsed time set value FCMAX.
It is determined whether it is less than (for example, 1 second).

If it is determined that the normal fuel cut mode has the longest elapsed time set value FCMAX, step 15
Then, the fuel injection from the fuel injector 24 of the predetermined cylinder set in the normal fuel cut mode is cut.

By thus cutting the fuel injection from the fuel injector 24 of the predetermined cylinder set in the normal fuel cut mode, the torque generated by the engine 20 is reduced and the slip of the drive wheels 28 is suppressed.

On the other hand, the slip ratio of the drive wheels 28 is large,
When the torque reduction request is for a long time, the normal fuel cut mode is stopped and the multi-cylinder fuel cut mode is entered. That is, when it is determined that the normal fuel cut mode elapsed time JFCON measured in step 14 is equal to or longer than the longest elapsed time set value FCMAX, the mode determination flag FM = 1 is set in step 16, and the multi-cylinder fuel after step 17 is set. Switch to cut mode.

In step 17, the multi-cylinder fuel cut mode elapsed time JTFCTI is measured, and in step 18, the longest elapsed time set value T of the multi-cylinder fuel cut mode is set.
FCTIM is calculated by the following formula.

TFCTIM = FCMAX × FCRATE (4) where FCRATE is a time ratio set according to the engine load and the engine speed N based on the map shown in FIG. In this map, the engine 20 rotation is low,
FCRATE is set to be smaller as the load on the engine 20 is lower.

Subsequently, it is determined whether the multi-cylinder fuel cut mode elapsed time JTFCTI measured in step 19 is less than the longest elapsed time set value TFCTIM.

Multi-cylinder fuel cut mode elapsed time J
When it is determined that TFCTI is less than the longest elapsed time set value TFCTIM, the routine proceeds to step 20, where fuel injection from the fuel injector 24 of the predetermined cylinder set in the multi-cylinder fuel cut mode is cut. In the multi-cylinder fuel cut mode, in the case of the engine 20 including eight cylinders, for example, fuel injection for six cylinders is cut.

Multi-cylinder fuel cut mode elapsed time J
When it is determined that the TFCTI is equal to or longer than the longest elapsed time set value TFCTIM, the process proceeds to step 21, and each fuel cut mode elapsed time JFCON, JTFC
Each TI is cleared and the mode determination flag FM = 0 is set. As a result, the fuel injection from the fuel injector 24 of the predetermined cylinder set in the normal fuel cut mode is cut again, the torque generated by the engine 20 is continuously reduced, and the slip of the drive wheels 28 is suppressed.

When it is determined in step 11 that there is no torque down request (TD = 0), the routine proceeds to step 22 and thereafter to measure the normal fuel cut mode elapsed time JFCON or the multi-cylinder fuel cut mode elapsed time JTFCTI. Then, when the torque reduction request is issued again, the normal fuel cut mode elapsed time JFCON or the multi-cylinder fuel cut mode elapsed time JTFCTI is set to the longest elapsed time set value FCMAX, T.
It is controlled not to exceed FCTIM.

While there is no torque down request, step 2
7 Multi-cylinder fuel cut mode elapsed time JTFCT
When it is determined that I becomes equal to or longer than the longest elapsed time set value TFCTIM, the routine proceeds to step 29, where each fuel cut mode elapsed time JFCON, JTFCTI is cleared and the mode determination flag FM = 0.
Set to.

FIG. 7 shows an example of control by the conventional system and an example of control by the system of the present invention.

In the conventional system, even if the slip ratio of the drive wheels 28 is large and the slip is not suppressed only by the normal fuel cut mode, if the torque reduction request exceeds the maximum elapsed time set value FCMAX, the injectors 24 of all the cylinders are operated. Fuel injection is restarted. As a result, the amount of unburned HC in the exhaust gas guided to the catalytic converter 26 is reduced and the heat of reaction of the catalytic converter 26 is suppressed by maintaining the heat resistance of the catalytic converter 26. Without degrading
The slip of the drive wheel 28 is not suppressed.

In the system of the present invention, when the slip ratio of the drive wheels 28 is large and the torque down request exceeds the maximum elapsed time set value FCMAX, the normal fuel cut mode is switched to the multi-cylinder fuel cut mode, and the injector 24 The number of cylinders whose fuel injection is cut is increased.

When the number of cylinders from which the fuel injection from the injector 24 is cut is increased, the amount of fresh air from the cylinder from which the fuel injection is cut increases, so that the temperature of the exhaust gas guided to the catalytic converter 26 decreases. At the same time, the number of cylinders whose fuel injection is not cut is reduced, so that the amount of unburned HC guided to the catalytic converter 26 is reduced and the reaction heat generated in the catalytic converter 26 is suppressed. As described above, in the conventional system, by increasing the number of cylinders in which the fuel cut is performed and continuing the fuel cut under the operating condition in which the fuel cut from the injector 24 is prohibited, the reaction heat generated in the catalytic converter 26 is suppressed. While maintaining the heat resistance of the catalytic converter 26, the torque generated by the engine 20 decreases, and for example, the drive wheels 28 are also used when the vehicle runs on a snowy road.
Slip is effectively suppressed.

Multi-cylinder fuel cut mode elapsed time J
When TFCTI becomes equal to or longer than the longest elapsed time set value TFCTIM, the fuel injection from the fuel injector 24 of the predetermined cylinder set in the normal fuel cut mode is cut again. As a result, the torque generated by the engine 20 is continuously reduced, and the slip of the drive wheels 28 is effectively suppressed.

As shown in the map of FIG. 6, the engine 20
Is low, and the load of the engine 20 is low, the F
By setting CRATE to be small,
Longest elapsed time set value T in multi-cylinder fuel cut mode
FCTIM becomes shorter. As a result, the fuel cut in the normal fuel cut mode is continued without worrying that the temperature of the catalytic converter 26 exceeds the allowable level in the low speed and low load range where the exhaust temperature of the engine 20 is low, and the slip of the drive wheels 28 is continued due to the continued fuel cut. Suppressed as requested. That is, the frequency of request for torque reduction is high, and the engine 20
In the low speed and low load range where the exhaust gas temperature is low, the longest elapsed time TF
Since the CTI is set to be relatively short, it is possible to increase the frequency at which the fuel cut is normally performed and appropriately reduce the torque so as not to give the driver a feeling of excessive deceleration.

When the rotation and load of the engine 20 are high, the longest elapsed time set value TFCTIM of the multi-cylinder fuel cut mode becomes long, and the temperature of the catalytic converter 26 becomes an allowable level in the high speed and high load region where the exhaust temperature is high. Is reliably prevented. In this case, the frequency of performing the multi-cylinder fuel cut may be increased to give the driver an excessive feeling of deceleration, but the heat resistance of the catalytic converter 26 is prioritized.

After the torque down request is once canceled during the multi-cylinder fuel cut mode, the torque down request is issued again while the multi-cylinder fuel cut mode elapsed time JTFCTI does not exceed the maximum elapsed time set value TFCTIM. Then, the multi-cylinder fuel cut is performed. As a result, for example, when the vehicle travels on a snowy road and there is an intermittent torque reduction request, the fuel cut in the normal fuel cut mode is performed without much time after the fuel cut in the multi-cylinder fuel cut mode is performed. Is avoided, and the heat resistance of the catalytic converter and the like can be secured.

In this way, the number of cylinders in which fuel cut is performed can be controlled in accordance with the operating conditions of the engine 20, and the operating range in which traction control is performed can be expanded.

[0061]

As described above, the engine fuel cut control apparatus according to claim 1 continues the fuel cut by increasing the number of cylinders in which the fuel cut is performed even under the operating condition where the fuel cut is prohibited in the conventional system. With such a configuration, it is possible to suppress the reaction heat generated in the catalytic converter or the like and maintain the heat resistance, while reducing the torque generated by the engine. Also, the multi-cylinder fuel cut mode has passed
Time JTFCTI is longer than the longest elapsed time TFCTIM
Is determined and the multi-cylinder fuel cut mode is terminated.
The heat resistance of the catalytic converter etc.
However, the multi-cylinder fuel cut is performed longer than necessary.
To prevent the driver from feeling excessive deceleration.
The torque can be properly reduced.

An engine fuel cut control apparatus according to a second aspect of the present invention calculates a slip ratio based on the detected rotation state of the drive wheels, and outputs a torque down request signal for the engine based on the calculated slip ratio. With this configuration, the duration of fuel cut is controlled according to the slip ratio of the drive wheels, and the slip of the drive wheels is effectively suppressed even when the vehicle is traveling on a snowy road, for example.

[0063]

The engine fuel cut control apparatus according to the third aspect of the present invention has a configuration in which the elapsed time JTFCTI after the multi-cylinder fuel cut mode is entered is continuously measured even if the torque reduction request is canceled. Avoid running fuel cut in normal fuel cut mode without waiting too long after fuel cut in multi-cylinder fuel cut mode when torque down request continues intermittently while traveling on snowy road Therefore, the heat resistance of the catalytic converter and the like can be secured.

[0065] The fuel cut control apparatus for an engine according to claim 4, high frequency of requests torque reduction, since the exhaust temperature is low a low speed low load region of the engine, the longest elapsed time TFCTI is set relatively short, Normally, the frequency of fuel cut is increased, and the torque can be properly reduced so that the driver does not feel excessive deceleration. On the other hand, in the high-speed and high-load range where the exhaust temperature of the engine is high, the longest elapsed time TFCTI is set to be relatively long, so that the frequency with which the multi-cylinder fuel cut is performed can be increased and the heat resistance of the catalytic converter and the like can be secured.

[Brief description of drawings]

FIG. 1 is a mechanical system diagram showing an embodiment of the present invention.

FIG. 2 is a block diagram of a control system of the same.

FIG. 3 is a flowchart showing a control content for similarly determining a torque down request.

FIG. 4 is a flowchart showing the contents of torque down control.

FIG. 5 is a flowchart showing the contents of torque down control.

FIG. 6 is a map that also sets ECRATE.

FIG. 7 is a timing chart showing an example of torque down control.

FIG. 8 is a diagram corresponding to claims of the invention according to claim 1.

FIG. 9 is a claim correspondence diagram of the invention according to claim 2;

FIG. 10 is a claim correspondence diagram of the invention according to claim 3;

[Explanation of symbols]

20 engine 23 Throttle chamber 24 Fuel injector 25 exhaust pipe 26 Catalytic converter 28 drive wheels 30 throttle valve 32 Throttle opening sensor 34 Air Flow Meter 36 Throttle opening sensor 35 crank angle sensor 36 Water temperature sensor 37 Oxygen sensor 38 Catalyst floor sensor 40 Drive wheel speed sensor 41 Driven wheel 42 Driven wheel speed sensor 45 control unit 101 Torque down demand determination means 102 fuel supply means for all cylinders 103 Normal fuel cut means 104 Normal fuel cut mode duration measuring means 105 Multi-cylinder fuel cut mode area determination means 106 multi-cylinder fuel cut means 111 Drive wheel rotation state detecting means 112 Slip ratio calculation means 113 Torque down signal output means

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI F02D 41/04 330 F02D 41/04 330G (58) Fields surveyed (Int.Cl. ⁷ , DB name) F02D 29/02 311 B60K 41/00-41/28 F01N 3/00-3/38 F02D 17/00-17/04 F02D 29/00-29/06 F02D 41/00-45/00 B60K 28/16

Claims (4)

(57) [Claims] 1. A torque down request judging means for judging a torque down request time, a normal fuel cut means for stopping a fuel supply to a part of cylinders having a predetermined number of cylinders as an upper limit at the time of torque down request, and a torque. Elapsed time since entering the down request JFCON
And a multi-cylinder fuel cut mode range determining means for determining a multi-cylinder fuel cut mode range in which the normal fuel cut mode elapsed time JFCON is longer than the longest elapsed time FCMAX. Multi-cylinder fuel cut means for stopping fuel supply to a predetermined number of cylinders that does not fall below the upper limit in the cut mode range, and fuel supply for each cylinder that controls fuel supply to each cylinder according to the determined fuel cut mode The control means and the normal fuel cut mode elapsed time JFCON are
The longest elapsed time since reaching FCMAX JTF
When the multi-cylinder fuel cut mode for measuring CTI elapses
Measuring means and elapsed time of multi-cylinder fuel cut mode
JTFCTI must be the longest elapsed time TFCTIM or more
Is determined and the multi-cylinder fuel cut mode is ended.
A fuel cut control device for an engine, comprising: multi-cylinder fuel cut mode ending means . 2. A drive wheel rotation state detecting means for detecting a rotation state of a drive wheel of a vehicle, a slip ratio calculating means for calculating a slip ratio based on the rotation state of the drive wheel, and an engine based on the slip ratio. 2. A fuel cut control device for an engine according to claim 1, further comprising a torque down signal output means for outputting a torque down request signal. 3. The end of the multi-cylinder fuel cut mode
Multi-cylinder fuel cut mode elapsed time JTFC
Torque before TI reaches maximum elapsed time TFCTIM
Multi-cylinder fuel cut if the down request is no longer
When the mode ends and the multi-cylinder fuel cut mode elapses
Since JTFCTI reaches the longest elapsed time TFCTIM
Multi-cylinder fuel if there was a previous torque down request
A contract characterized by a configuration for restarting the cut mode
Fuel cut system for the engine according to claim 1 or 2
Your device . 4. The maximum elapsed time TFCTI of the engine
Set so that it becomes longer in the high speed and high load range than in the low speed and low load range.
According to any one of claims 1 to 3, characterized in that
Fuel cut control device for the engine .