JP2002004908A - Driving force control device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel-cut traction control device for preventing damage to an engine and a catalyzer due to overheat while enabling output torque control of an engine with the change of a fuel-cut cylinder number. SOLUTION: One of a first fuel-cut cylinder number (one cylinder) set by first fuel-cut cylinder number setting means M2 in response to the slipping condition of driving wheels and a second fuel-cut cylinder number (zero and two cylinders), different from the first fuel-cut cylinder number, set by second fuel-cut cylinder number setting means M3 is selected in response to the overheated condition of the engine E and the catalyzer C. In the fuel cut of one cylinder, if overheat is generated, alternate fuel cut in the zero cylinder and two cylinders is carried out, so that the output torque of the engine E is reduced while preventing damage to the engine E and the catalyzer C due to the overheat, to inhibit the overslip of the driving wheels.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving force control apparatus for a vehicle which suppresses the excessive slip by reducing the output torque of an engine by fuel cut when excessive slip of a driving wheel is detected.

[0002]

2. Description of the Related Art A traction control device that suppresses the excessive slip by reducing the output torque of an engine by fuel cut control when excessive slip of a driving wheel is detected at the time of starting or accelerating on a road surface with a low friction coefficient,
For example, it is known from Japanese Patent Application Laid-Open No. 1-290934.

In such a traction control device, when the output torque reduction ratio of the engine is calculated according to the slip ratio of the driving wheels, the number of fuel cut cylinders is determined according to the output torque reduction ratio. For example, in a four-cylinder engine, as shown in FIG. 12, when the requested output torque reduction rate is 0%, fuel cut is not performed (zero cylinder fuel cut), and when the requested output torque reduction rate is 25%, one cylinder fuel cut is performed. When 50%, two-cylinder fuel cut is performed, when 75%, three-cylinder fuel cut is performed, and when 100%, four-cylinder fuel cut is performed.

[0004]

Generally, the temperature of a catalyst for purifying exhaust gas provided in an exhaust passage of an engine has the highest air-fuel ratio at a stoichiometric air-fuel ratio (14 to 15). In the four-cylinder engine illustrated in FIG. 13, when there is no fuel cut indicated by a solid line, the catalyst temperature is 900 ° C. which is the upper limit temperature at which the deterioration of the catalyst is promoted in the range of 13 to 17 including the stoichiometric air-fuel ratio. (Refer to the broken line), but at the normal air-fuel ratio indicated by the ellipse, the catalyst temperature is kept below the upper limit temperature.

However, if one-cylinder fuel cut is performed to reduce the output torque of the engine, the peak of the catalyst temperature shifts to the low air-fuel ratio side as indicated by the one-dot chain line, and the catalyst temperature reaches the upper limit in the normal air-fuel ratio region. There is a problem of exceeding the temperature. Further, when the fuel cut of two or more cylinders is performed, the peak of the catalyst temperature further shifts to the low air-fuel ratio side, so that the catalyst temperature in the normal air-fuel ratio region is again suppressed to the upper limit temperature or lower. In the case where the number of fuel cut cylinders is changed according to the output torque reduction rate requested in such a manner, when the number of fuel cut cylinders reaches a specific value, the catalyst temperature exceeds the upper limit temperature, and catalyst damage or damage may occur. There is a problem that causes deterioration. In addition, the exhaust gas temperature also changes in the same manner as the catalyst temperature in accordance with the number of fuel cut cylinders, causing a problem such as melting of the piston.

The present invention has been made in view of the above circumstances, and has as its object to prevent engine and catalyst damage due to overheating while enabling control of engine output torque by changing the number of fuel cut cylinders. .

[0007]

According to the first aspect of the present invention, when an excessive slip of a driving wheel is detected, the output torque of the engine is reduced by fuel cut. In the vehicle driving force control device for suppressing the excessive slip, a slip state detecting means for detecting a slip state of a drive wheel and a first fuel cut cylinder number are set according to the slip state detected by the slip state detecting means. First fuel cut cylinder number setting means, a second fuel cut cylinder number setting means for setting a second fuel cut cylinder number different from the first fuel cut cylinder number set by the first fuel cut cylinder number setting means, and an engine. Operating state detecting means for detecting an operating state of the engine, and a first fuel cell according to an operating state of the engine detected by the operating state detecting means. A driving means for a vehicle, comprising: selecting means for selecting the number of fuel cut cylinders or the number of second fuel cut cylinders; and fuel cut control means for performing fuel cut based on the number of fuel cut cylinders selected by the selecting means. A control device is proposed.

[0008] According to the above configuration, the first fuel cut cylinder number set by the first fuel cut cylinder number setting means and the first fuel cut cylinder number set by the second fuel cut cylinder number setting means according to the slip state of the drive wheels. Since either one of the number of fuel cut cylinders and the second number of fuel cut cylinders is selected according to the operating state of the engine, if the fuel cut is performed with the first number of fuel cut cylinders, the engine and the catalyst may be overheated. In this case, by performing fuel cut with the second fuel cut cylinder number set in the second fuel cut cylinder number, the engine output torque is reduced while preventing damage to the engine and the catalyst due to overheating, and excessive slip of the drive wheels is performed. Can be suppressed.

According to the invention described in claim 2,
In addition to the configuration of claim 1, the second fuel cut cylinder number setting means sets two different second fuel cut cylinder numbers, and when the selection means selects the second fuel cut cylinder number, the fuel cut control means There is proposed a driving force control device for a vehicle, wherein fuel cuts are alternately performed with the two second fuel cut cylinders.

According to the above configuration, when the two second fuel cut cylinder numbers set by the second fuel cut cylinder number setting means are selected, the fuel cut is alternately performed with the two second fuel cut cylinder numbers. By doing so, the output torque can be reduced while suppressing fluctuations in the engine output torque, and excessive slip of the drive wheels can be suppressed.

According to the third aspect of the present invention,
In addition to the configuration of claim 2, the driving force control device for a vehicle is characterized in that the two second fuel cut cylinders are one number larger and one smaller than the first fuel cut cylinder. Suggested.

According to the above configuration, the two second fuel cut cylinder numbers set by the second fuel cut cylinder number setting means are equal to the first fuel cut cylinder number ± 1 set by the first fuel cut cylinder number setting means. Therefore, the variation in the output torque of the engine when the fuel cut is performed alternately with the two second fuel cut cylinders can be minimized.

Further, according to the invention described in claim 4,
In addition to the configuration according to any one of claims 1 to 3, the operating state of the engine detected by the operating state detecting means is at least one of a temperature of an exhaust gas of the engine and a temperature of a catalyst for purifying exhaust gas. A vehicle driving force control device is proposed.

According to the above configuration, since the operating state detecting means detects the temperature of the exhaust gas of the engine or the temperature of the catalyst for purifying the exhaust gas, it is possible to effectively prevent engine damage and catalyst damage due to overheating. Can be.

According to the invention described in claim 5,
In addition to the configuration according to any one of claims 1 to 3, the operating state of the engine detected by the operating state detecting means is based on at least one of an upper limit temperature of an exhaust gas temperature of the engine and a temperature of an exhaust gas purifying catalyst. A driving force control device for a vehicle, which is characterized by an engine speed, is proposed.

According to the above configuration, since the engine speed corresponding to at least one of the upper limit temperature of the exhaust gas temperature of the engine and the temperature of the exhaust gas purifying catalyst is detected, engine damage or catalyst damage due to overheating is detected. Can be effectively prevented.

In the present invention, the number of fuel cut cylinders includes zero cylinders.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described based on embodiments of the present invention shown in the accompanying drawings.

1 to 11 show an embodiment of the present invention. FIG. 1 is a block diagram showing a configuration of a driving force control device for a vehicle, FIG. 2 is a flowchart of a main routine, and FIG. 3 is a fuel cut interval. FIG. 4 is a flowchart of an exhaust / catalyst temperature determination necessity determination routine, FIG. 5 is a flowchart of an exhaust / catalyst temperature estimation routine, and FIG. 6 is a time chart of a first counter, a second counter and a torque down control value. , FIG. 7 is a map for judging the necessity of suppressing the exhaust gas and CAT temperature from the engine speed and the intake negative pressure, FIG. 8 is a map for searching the initial catalyst temperature correction coefficient from the water temperature and the intake temperature, and FIG. FIG. 10 is a map for searching for coefficients for estimating exhaust and catalyst temperatures. FIG. 10 shows one-cylinder fuel cut control and fuel tank control. Graph showing changes in the catalyst temperature by preparative interval control, FIG. 11 is a graph showing a change in engine torque by 1 cylinder fuel-cut control and the fuel cut interval control.

As shown in FIG. 1, when excessive slip of the drive wheels is detected, the engine E
The vehicle driving force control device U that suppresses the excessive slip by reducing the output torque of the vehicle includes a slip state detection unit M1
First fuel cut cylinder number setting means M2, second fuel cut cylinder number setting means M3, operating state detection means M4, selection means M5, and fuel cut control means M6.
And

The slip state detecting means M1 detects the slip state of the driving wheels based on the driving wheel speed detected by the driving wheel speed detecting means Sa and the driven wheel speed detected by the driven wheel speed detecting means Sb. The first fuel cut cylinder number setting means M2 sets the number of first fuel cut cylinders required to eliminate the slip state according to the slip state of the drive wheel detected by the slip state detection means M1.
The engine E of the embodiment is a four-cylinder engine, and the first fuel cut cylinder number set by the first fuel cut cylinder number setting means M2 is five types from zero cylinder to four cylinders.

Second fuel cut cylinder number setting means M3
Corresponds to the first fuel cut cylinder number set by the first fuel cut cylinder number setting means M2 according to the slip state of the drive wheel detected by the slip state detection means M1,
For example, two second fuel cut cylinder numbers are set. The specific first fuel cut cylinder number set by the first fuel cut cylinder number setting means M2 is one cylinder in the embodiment,
This number of cylinders corresponds to the number of fuel cut cylinders at which the temperature of the exhaust gas of the engine E rises or the temperature of the catalyst C for purifying the exhaust gas rises. In the embodiment, the two second fuel cut cylinder numbers set by the second fuel cut cylinder number setting means M3 are, in the embodiment, 0 cylinder which is one less than one cylinder which is the specific fuel cut cylinder number, and one more two cylinders. With cylinders.

The operating state detecting means M4 includes an engine speed NE detected by the engine speed detecting means Sc, an intake negative pressure PB detected by the intake negative pressure detecting means Sd, and a throttle detected by the throttle opening detecting means Se. The exhaust gas temperature of the engine E or the temperature of the exhaust gas purifying catalyst C is estimated based on the opening degree TH.

When the first fuel cut cylinder number setting means M2 sets the specific first fuel cut cylinder number (one cylinder), the selection means M5 selects the engine E or the engine E based on the detection result of the operation state detection means M4. When it is determined that the catalyst C is not likely to be damaged due to overheating, the first fuel cut cylinder number (one cylinder) is directly selected. If it is determined that the engine E or the catalyst C may be damaged by overheating, the two second fuel cut cylinder numbers set by the second fuel cut cylinder number setting means M3 are selected.

The fuel cut control means M6 controls the fuel cut of the engine E based on the number of fuel cut cylinders selected by the selection means M5, reduces the output torque of the engine E, and suppresses excessive slip of the drive wheels. At this time, if the two second fuel cut cylinder numbers set by the second fuel cut cylinder number setting means M3 are selected,
The two second fuel cut cylinder numbers are alternately switched at predetermined time intervals or at predetermined crankshaft rotation speed intervals. With this fuel cut interval control,
The output torque of the engine E can be reduced without hindrance while preventing the engine E or the catalyst C from overheating.

Next, the operation of this embodiment will be described with reference to the flowcharts of FIGS.

First, step S of the main routine shown in FIG.
If the engine speed NE does not exceed the lower limit speed NEVSAL in step S1 and the torque down control value TCLVL = 00h (no fuel cut) is output by the interval control in step S3, the torque down control is executed in step S4. Without executing, torque down control value TCL
VL = 00h is set. Even if the engine speed NE exceeds the lower limit speed NEVSAL in the step S1, the throttle opening TH does not exceed the lower limit throttle opening THVSAL in the step S2, and the torque reduction control is performed by the interval control in the step S3. Value TC
If LVL = 00h (no fuel cut) is not output, the torque-down control value is set to TCLVL = 00h without executing the torque-down control in step S4.

When the engine speed NE is equal to the lower limit speed NEVS
The reason why the torque down control is not executed when the engine speed does not exceed AL is to prevent the engine E from being stalled.
Also, the throttle opening TH is equal to the lower limit throttle opening THVS.
The reason why the torque-down control is not executed when the vehicle speed does not exceed AL is that unnecessary and time-delayed torque-down control is performed when the driver voluntarily returns the accelerator pedal to prevent excessive slip of the drive wheels. This is to prevent the driver from feeling uncomfortable.

In step S1, the engine speed NE exceeds the lower limit speed NEVSAL, and in step S2, the throttle opening TH is set to the lower limit throttle opening TH.
If VSAL is exceeded, the torque down request value TCFC of the engine E corresponding to the slip ratio of the drive wheel is received in step S5, and the torque down request value TCFC is a sufficiently small level (control OFF level) in step S6. If so, it is not necessary to reduce the torque, and the process proceeds to step S3.

In step S6, the torque down request value T
If the CFC is not at the control OFF level and the torque down request value TCFC is not at the one-cylinder fuel cut level in step S7, that is, if there is no risk that the fuel cut will cause erosion of the piston or deterioration of the catalyst, step S7 is executed. In S8, the torque-down request value TCFC is directly used as the torque-down control value TCLVL, and the 0-cylinder, 2-cylinder,
The fuel cut of three or four cylinders is executed.

On the other hand, if the torque down request value TCFC is the one-cylinder fuel cut level in step S7,
That is, when there is a risk that the fuel cut may cause the piston to be damaged or the catalyst to be deteriorated, it is determined in step S9 whether it is necessary to control the exhaust gas temperature or the catalyst temperature. If the control is not necessary, the process proceeds to step S8 to execute the fuel cut of one cylinder. If the control is necessary, the process proceeds to step S10 to perform the interval control, that is, the fuel cut of the zero cylinder and the two cylinders. Are alternately executed at predetermined time intervals.

Next, a fuel cut interval control routine, which is a subroutine of step S10, will be described with reference to FIG.

In the first loop, since the previous interval control has not been performed in step S11, step S11 is executed.
14 sets the second counter CTCINT1 to the initial value $ CTCI.
NT1D is set, and in step S15, the torque-down control value TCLVL is set to 02h, and fuel cut of the two cylinders is started. In the next loop, the answer to step S11 is YES, and the process proceeds to step S12, where
In step 12, since the two-cylinder fuel cut of the interval control has been performed, the process proceeds to step S16. Since the second counter CTCINT1 has not yet timed out in step S16, the second counter CT
CINT1 is decremented, and the routine goes to Step S15. Steps S11 → S12 → S16 → S20 → S
If the second counter CTCINT1 times out while continuing the two-cylinder fuel cut while repeating the loop of No. 15, the answer to step S16 becomes YES and the process proceeds to step S17. And step S17
Sets the first counter CTCINT0 to the initial value $ CTCINT
It is set to 0D, and in step S18, the torque-down control value TCLVL is set to 00h, and the fuel cut of the 0 cylinder is started.

In the next loop, the answer at step S12 is N
It becomes O and it transfers to step S13. Step S13
In step S19, the first counter CTCIN0 has not yet timed out.
T0 is decremented, and the routine goes to Step S18. If the first counter CTCINT0 times out while continuing the zero-cylinder fuel cut while repeating the loop of steps S11 → S12 → S13 → S19 → S18, the answer to step S13 becomes YES and the process proceeds to step S14. I do. Then, in step S14, the second
The counter CTCINT1 is set to the initial value $ CTCINT1D, and the torque down control value TCL is set at step S15.
VL is set to 02h, and fuel cut of two cylinders is started.

The above operation will be described with reference to the time chart of FIG. When the interval control is started, the second counter CTCINT1 is set to the initial value $ CTCINT1D, and the fuel cut of the two cylinders is executed until the time is up. And the second counter CTCINT
When 1 is up, the first counter CTCINT0
Is set to the initial value $ CTCINT0D, and the fuel cut of the zero cylinder is executed until the time is up. Therefore, the fuel cut of the two cylinders and the fuel cut of the zero cylinder are alternately performed at predetermined time intervals (or a time corresponding to 10 rotations of the crankshaft).

As shown in FIG. 10, when a one-cylinder fuel cut is performed (see the dashed line), the catalyst temperature rises from 900 ° C. which is the upper limit temperature to 1000 ° C. for the reason explained in FIG. Would. On the other hand, when the zero-cylinder fuel cut and the two-cylinder fuel cut are alternately performed (see the solid line), the catalyst temperature is maintained at 820 ° C., which is 900 ° C. or less, which is the upper limit temperature, and damage or deterioration of the catalyst C is prevented. It is surely prevented.

As shown in FIG. 11, when the one-cylinder fuel cut is performed (see the dashed line), the output torque of the engine E hardly fluctuates, but the zero-cylinder fuel cut and the two-cylinder fuel cut are alternately performed. When this operation is performed (see the solid line), the output torque of the engine E fluctuates.
However, the fluctuation of the output torque of the engine E has a short period and a small amplitude, so that it does not pose any practical problem. Therefore, by alternately performing the 0-cylinder fuel cut and the 2-cylinder fuel cut, the engine E
It is possible to suppress an increase in the catalyst temperature or an increase in the exhaust gas temperature while appropriately reducing the output torque of the exhaust gas.

Next, an exhaust gas / catalyst temperature control necessity determination routine, which is a subroutine of the step S9, is shown in FIG.
It will be described based on.

First, at step S21, the engine speed N
From the map of FIG. 7 based on E and the intake negative pressure PB, the criterion upper limit value PBFCINTH and the criterion lower limit value PB are determined.
Search FCINTL. A region H in which the engine speed NE and the intake negative pressure PB are higher than the criterion upper limit value PBFCINTH is a region in which the interval control is executed irrespective of the exhaust gas temperature and the catalyst temperature, and the criterion lower limit value PB
A region L lower than FCINTL is a region where the interval control is stopped irrespective of the exhaust gas temperature or the catalyst temperature, and a region M sandwiched between the criterion upper limit PBFCINTH and the criterion lower limit PBFCINTL is the exhaust gas temperature or the catalyst temperature. Is an area in which the interval control is executed or stopped according to.

In step S22, the intake negative pressure PB (and the engine speed NE) is reduced to the criterion upper limit value PBFCINTH.
And the intake negative pressure PB is determined in step S23.
(And the engine speed NE) is equal to the judgment reference lower limit value PBF.
If it is less than CINTL, it is determined that the area is the area L, and the interval control is stopped in step S24. In step S22, the intake negative pressure PB (and the engine speed N
If E) exceeds the criterion upper limit value PBFCINTH, without directly monitoring the exhaust gas temperature or the catalyst temperature,
It is determined that the region is a region H where damage to the engine E and damage to the catalyst C due to overheating may occur, and the interval control is executed in step S25.

In step S22, the intake negative pressure PB (and the engine speed NE) is reduced to the criterion upper limit value PBFCIN.
If TH has not exceeded TH and the intake negative pressure PB (and the engine speed NE) is not less than the criterion lower limit value PBFCINTL in step S23, it is determined to be in the area M, and the process proceeds to step S26. And step S26
The exhaust gas temperature TCYLEX is the upper limit value of the exhaust gas temperature TC
If it exceeds YLEXH, the interval control is executed in step S25. In step S26, the exhaust gas temperature TCYLEX is changed to the exhaust gas temperature upper limit TCYL.
If it does not exceed EXH and the catalyst temperature TCAT exceeds the catalyst temperature upper limit TCATH in step S27,
Interval control is executed in step S25. If the exhaust gas temperature TCYLEX does not exceed the exhaust gas temperature upper limit TCYLEXH in the step S26, and if the catalyst temperature TCAT does not exceed the catalyst temperature upper limit TCATH in the step S27, the process proceeds to the step S24.
To stop the interval control.

Next, an exhaust gas / catalyst temperature estimation routine, which is a subroutine of steps S26 and S27, will be described with reference to FIG.

First, in step S31, in the case of the initial processing when the ignition switch is turned on, step S3
In step 5, the cooling water temperature TW at that time is estimated as the initial exhaust gas temperature TCYLEX. In the following step S36, the initial catalyst temperature correction coefficient KTCATINT is calculated from the cooling water temperature TW and the atmospheric temperature TA based on the map shown in FIG.
And the initial catalyst temperature correction coefficient KTCAT
From the INT and the catalyst temperature TCATBU immediately before the previous ignition switch was turned OFF, TCAT = KTCATINIT × TW + (1-KTCA
TINI) × TCATBU is used to estimate the initial catalyst temperature TCAT.

If the initial processing is completed in step S31 and if the engine E is not stall or the starter motor is not operating in step S32, step S3 is executed.
In step S3, the exhaust gas temperature TCYLEX after the start of the engine E is estimated, and in step S34, the catalyst temperature T
Estimate the CAT.

Exhaust gas temperature TCYL after engine E starts
EX and the catalyst temperature TCAT are estimated separately during fuel injection (including during fuel cut for some cylinders) and during fuel cut (during fuel cut for all cylinders).

Exhaust gas temperature during fuel injection TCYLEX
Is based on the annealing constant KTEX, the basic exhaust gas temperature TCLYEXB at the time of the stoichiometric air-fuel ratio, the exhaust gas temperature correction coefficient KTCYLEX when the air-fuel ratio is changed, and the previous exhaust gas temperature TCYLEX (n-1). TCYLEX = KTEX × TCLYEXB × KTCYL
EX + (1-KTEX) × TCYLEX (n-1). Basic exhaust gas temperature T at stoichiometric air-fuel ratio
CLYEXB is retrieved from the map of FIG. 9A based on the fuel injection amount TI and the engine speed NE, and the exhaust gas temperature correction coefficient KTCYLEX when changing the air-fuel ratio is calculated based on the air-fuel ratio coefficient KA / F in FIG. A search is made from the map of (B).

Exhaust gas temperature TCYL during fuel cut
EX is an annealing constant KTEX, an atmospheric temperature TA, and a basic exhaust gas temperature change coefficient KTEXFC during fuel cut.
TCYLEX = KTEX × TA × KTEXFC + (1− based on the previous exhaust gas temperature TCYLEX (n−1)
KTEX) × TCYLEX (n-1). The basic exhaust gas temperature change coefficient KTEXFC during fuel cut is retrieved from the map of FIG. 9C based on the engine speed NE.

The catalyst temperature TCAT during fuel injection is calculated based on two smoothing coefficients KTCAT and KCATEX, a catalyst temperature correction coefficient KTCYLEX when changing the air-fuel ratio, and a previous catalyst temperature value TCAT (n-1). TCAT = KTEX × TCLYE × KTCYLEX +
It is given by (1−KTCAT) × TCAT (n−1). Catalyst temperature correction coefficient KTC when changing air-fuel ratio
YLEX is retrieved from the map in FIG. 9D based on the air-fuel ratio coefficient KA / F and the in-catalyst air-fuel ratio calculation coefficient KVSAFC. The catalyst air-fuel ratio calculation coefficient KVSAFC
Is, when the total number of cylinders is 4 and the torque down control value (that is, the number of cylinders during fuel cut) is TCLVL,
(4-TCLVL) / 4.

The catalyst temperature TCAT during fuel cut is:
The annealing constant KTCAT, the atmospheric temperature TA, and the basic exhaust gas temperature change coefficient KTEXFC during fuel cut (FIG. 9)
(C)) and the previous value of the catalyst temperature TCAT (n-1)
TCAT = KTCAT × TA × KTEXFC + (1-K
TCAT) × TCAT (n−1).

Although the embodiments of the present invention have been described in detail, various design changes can be made in the present invention without departing from the gist thereof.

For example, in the embodiment, a four-cylinder engine E has been exemplified, but the present invention is applicable to a multi-cylinder engine other than the four-cylinder engine. In the embodiment, the number of first fuel cut cylinders is one, and the number of two second fuel cut cylinders is zero and two. However, the present invention is not limited to this. That is, in the invention described in claim 1, the second fuel cut cylinder number setting means M3 does not necessarily need to set two second fuel cut cylinder numbers, but only sets one second fuel cut cylinder number. But it is good.

[0052]

As described above, according to the first aspect of the present invention, the first fuel cut cylinder number set by the first fuel cut cylinder number setting means according to the slip state of the drive wheel, and the second fuel cut cylinder number Either the first fuel cut cylinder number set by the fuel cut cylinder number setting means or the second fuel cut cylinder number different from the first fuel cut cylinder number is selected according to the operating state of the engine, so that the fuel cut is performed using the first fuel cut cylinder number. When there is a risk that the engine or the catalyst may be overheated by performing the above, by performing the fuel cut with the second number of the fuel cut cylinders set by the second number of the fuel cut cylinders, it is possible to prevent the engine and the catalyst from being damaged by the overheating while preventing the engine and the catalyst from being damaged. , The output torque of the drive wheels can be reduced to suppress excessive slip of the drive wheels.

According to the second aspect of the present invention,
When two second fuel cut cylinder numbers set by the second fuel cut cylinder number setting means are selected, the fuel cut is alternately performed with the two second fuel cut cylinder numbers, thereby reducing the output torque of the engine. The output torque can be reduced while suppressing the fluctuation, so that excessive slip of the drive wheels can be suppressed.

According to the third aspect of the present invention,
Since the two second fuel cut cylinder numbers set by the second fuel cut cylinder number setting means are the first fuel cut cylinder numbers ± 1 set by the first fuel cut cylinder number setting means, two second fuel cut cylinder numbers are set. Fluctuations in engine output torque when fuel cuts are performed alternately with the number of cylinders are minimized.

According to the fourth aspect of the present invention,
Since the operating state detecting means detects the temperature of the exhaust gas of the engine or the temperature of the catalyst for purifying the exhaust gas, it is possible to effectively prevent engine damage and catalyst damage due to overheating.

According to the invention described in claim 5,
Since the engine speed corresponding to the upper limit temperature of at least one of the temperature of the exhaust gas of the engine and the temperature of the catalyst for purifying the exhaust gas is detected, it is possible to effectively prevent engine damage and catalyst damage due to overheating. .

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a driving force control device for a vehicle.

FIG. 2 is a flowchart of a main routine.

FIG. 3 is a flowchart of a fuel cut interval control routine.

FIG. 4 is a flowchart of an exhaust / catalyst temperature suppression necessity determination routine;

FIG. 5 is a flowchart of an exhaust / catalyst temperature estimation routine.

FIG. 6 is a time chart of a first counter, a second counter, and a torque down control value.

FIG. 7 shows exhaust gas, CA from engine speed and intake negative pressure.
Map to judge the necessity of T temperature suppression

FIG. 8 is a map for searching for an initial catalyst temperature correction coefficient from water temperature and intake air temperature.

FIG. 9 is a map for searching for coefficients for estimating exhaust and catalyst temperatures after engine startup.

FIG. 10 is a graph showing a change in catalyst temperature by one-cylinder fuel cut control and fuel cut interval control.

FIG. 11 is a graph showing changes in engine torque by one-cylinder fuel cut control and fuel cut interval control.

FIG. 12 is a graph showing the relationship between the number of fuel cut cylinders and the output torque reduction rate.

FIG. 13 is a graph showing a change in catalyst temperature with respect to an air-fuel ratio and the number of fuel cut cylinders.

[Explanation of symbols]

 C catalyst E engine M1 slip state detection means M2 first fuel cut cylinder number setting means M3 second fuel cut cylinder number setting means M4 operating state detection means M5 selection means M6 fuel cut control means

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02D 45/00 312 F02D 45/00 312M 312R 312N (72) Inventor Hideyo Yamazaki 1-4-4 Chuo, Wako, Saitama No. 1 F-term in Honda R & D Co., Ltd. (reference) 3G093 BA01 BA17 DA17 DA03 DA04 DA06 DB03 DB17 EA05 FA10 FA11 3G301 JA32 JA33 JA38 KA26 KB00 MA11 MA24 NA08 NC04 NE07 NE17 PA07Z PA11Z PD11Z PD12Z PE01Z PE03Z PF00Z

Claims (5)

[Claims] 1. A driving force control device for a vehicle for suppressing an excessive slip by reducing an output torque of an engine (E) by a fuel cut when an excessive slip of a driving wheel is detected. A first fuel cut cylinder number setting means (M2) for setting the first fuel cut cylinder number according to the slip state detected by the slip state detection means (M1); A second fuel cut cylinder number setting means (M3) for setting a second fuel cut cylinder number different from the first fuel cut cylinder number set by the one fuel cut cylinder number setting means (M2); and an operating state of the engine (E) Operating state detecting means (M4) for detecting the first state of the engine (E) detected by the operating state detecting means (M3). Tsu bet the number of cylinders or the second
Selecting means (M5) for selecting the number of fuel cut cylinders; and fuel cut control means (M6) for performing fuel cut based on the number of fuel cut cylinders selected by the selecting means (M5). Vehicle driving force control device. 2. A second fuel cut cylinder number setting means (M)
3) sets two different second fuel cut cylinder numbers, and when the selecting means (M5) selects the second fuel cut cylinder number, the fuel cut control means (M6) sets the two second fuel cut cylinder numbers. The driving force control device for a vehicle according to claim 1, wherein fuel cuts are alternately performed by (1). 3. The number of the two second fuel cut cylinders is one greater than the number of the first fuel cut cylinders by one and one.
The driving force control device for a vehicle according to claim 2, wherein the number is smaller than the number. 4. The operating state of the engine (E) detected by the operating state detecting means (M4) is at least one of the temperature of the exhaust gas of the engine (E) and the temperature of the exhaust gas purifying catalyst (C). The driving force control device for a vehicle according to any one of claims 1 to 3, wherein: 5. The operating state of the engine (E) detected by the operating state detecting means (M4) is an upper limit of at least one of the temperature of the exhaust gas of the engine (E) and the temperature of the catalyst (C) for purifying the exhaust gas. The driving force control device for a vehicle according to any one of claims 1 to 3, wherein the driving speed is an engine speed corresponding to a temperature.