JPH116450A - Vehicle driving force control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the increase in an exhaust gas temperature through continuous operation of drive power control at a high load area and to protect an exhaust catalyst, in a vehicle driving force control device to control an engine output through cut of fuel injection. SOLUTION: A vehicle driving force control device comprises the slip ratio computing means to compute the slip ratio of a drive wheel; and a drive power control permission deciding means to permit control of a drive power when a computed slip ratio exceeds a slip control threshold. Since the slip control threshold is set to a high value when a shift lever is selected to the slip control threshold, Drive power control hardly occurs continuously at a high load region. This constitution prevents the increase of an exhaust temperature and prevents incurring of the heat loss of an exhaust catalyst and the occurrence of deterioration thereof.

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 device for preventing the idling of driving wheels and ensuring stability and driving performance of a vehicle, and more particularly to an improvement of a driving force control device having an automatic transmission. is there.

[0002]

2. Description of the Related Art A driving force control device (or a TC) for preventing a driving wheel from running idle during acceleration or the like to reduce acceleration performance.
S = Traction control system) includes a system that controls the engine output by controlling the opening of a second throttle driven by an actuator, a fuel injection cut, an ignition timing control, and the like, or a system that controls the idling of drive wheels by operating a braking device. What suppresses is known conventionally.

A driving force control device for controlling the output of an engine by cutting fuel injection is disclosed in Japanese Patent Laid-Open Publication No.
As disclosed in Japanese Patent No. 246335, when the idling of the driving wheel is detected, as shown in FIG. 5, the number of cylinders at which the fuel injection cut is performed is stepped according to the magnitude of the slip ratio of the driving wheel. There is known a device that changes the output of the engine to suppress the output of the engine.

As described above, the engine which suppresses the engine output by cutting the fuel injection has excellent responsiveness as compared with the engine which suppresses the engine output by controlling the throttle opening, and has a mechanism for controlling the throttle opening. And the like are unnecessary, and there is an advantage that the device configuration is simplified.

However, when the engine output is suppressed by cutting the fuel injection, only the air is exhausted from the cylinder from which the fuel injection has been cut, so that the amount of oxygen in the exhaust gas increases, which reacts with the unburned gas. This causes the exhaust temperature to rise. This tendency is particularly remarkable when the driving force control (fuel injection cut) is continuously performed in the high load range of the engine. When the exhaust catalyst is exposed to high-temperature exhaust gas, heat loss or deterioration of the exhaust catalyst is caused. Cause.

Therefore, in the conventional driving force control device, when driving force control is performed in the region of the large accelerator opening, the shift-up is accelerated to address this problem. That is, by shifting up faster than usual, the engine is operated so as not to enter the high load region, and the driving force control (fuel injection cut) is prevented from being performed in the high load region.

[0007]

However, such a method is effective only when the shift lever is selected to a D range in which the shift lever can be sequentially shifted up.
It is not possible to cope with the case where the L range in which the first speed is fixed and the upshift is not possible or the two ranges where the upshift is possible but the upshift is possible only in the second speed are selected.

As shown in FIG. 3, when the vehicle is accelerated in the L range, the speed is fixed to the first speed and the upshift is not performed.
When the driving wheel speed is low, it enters the high load area,
Further, even in the case of accelerating in two ranges, since the shift is performed only up to the second speed, the vehicle enters the high load region from the low speed region, though not as much as the L range.

For this reason, L is easily operated in a high load region.
When the range or two ranges are selected, the driving force control is easily performed continuously in the high load region, and the exhaust gas temperature rises due to the fuel cut, thereby causing heat loss and deterioration of the exhaust catalyst. was there.

The present invention has been made in view of this problem, and it is intended that the driving force control (fuel injection cut) is continuously performed in a high load region even when the L range or the two range is selected. It is an object of the present invention to protect the exhaust catalyst by preventing the exhaust gas temperature from rising.

[0011]

A first aspect of the present invention is a vehicle driving force control device having an automatic transmission, comprising: a slip ratio calculating means for calculating a slip ratio of a driving wheel; A driving force control permission determining means for permitting the driving force control when the threshold value is exceeded, a means for stopping the fuel supply to some cylinders when the driving force control is permitted, and And a slip control threshold value setting means for setting the slip control threshold value larger at a certain time.

Also, a second invention is a vehicle driving force control device having an automatic transmission,
A slip ratio calculating means for calculating a slip ratio of a driving wheel;
Driving force control permission determining means for permitting driving force control when the calculated slip ratio exceeds a slip control threshold value, and means for stopping fuel supply to some cylinders when driving force control is permitted And a means for detecting the selected position of the shift lever, and a slip control threshold value setting means for setting the slip control threshold value according to the selected position of the shift lever.

In a third aspect based on the second aspect, the slip control threshold value is set so as to increase as the shift lever is selected to a lower speed range.

In a fourth aspect based on the second aspect, the slip control threshold value is set to be large when the shift lever is selected to a fixed range.

[0015]

[Operation and effect] When driving force control is performed by cutting fuel injection to some cylinders, such as when a wheel slip occurs, the amount of oxygen in the exhaust gas increases because only air is exhausted from the cylinders where fuel injection has been cut. , And the unburned gas reacts to cause an increase in the exhaust gas temperature. This tendency becomes more remarkable as the vehicle is operated in a high load region.

Therefore, if the driving force control is continuously performed in the high load range, the possibility of damaging the exhaust catalyst increases. However, according to the first aspect, the slip control threshold value of the engine is reduced in the high load range. Since it is set to be large, in the high load region, the driving force control is not performed until the slip ratio increases. That is, since it is difficult to continuously perform the fuel injection cut in the high load region, the rise in the exhaust gas temperature is suppressed, and the exhaust catalyst can be prevented from being damaged.

According to the second aspect of the present invention, the selected position of the shift lever is detected, and the slip control threshold value is changed according to the selected position. The threshold can be set individually. For example, when a low speed range that is likely to enter the high load region is selected, the slip control threshold value is increased to prevent the fuel cut from being performed in the high load region, thereby protecting the exhaust catalyst.

According to the third aspect, the slip control threshold value is set higher as the shift lever is selected to the lower speed range, so that the L range or the two ranges which are more likely to be operated in a high load range are set. Is selected, the slip control threshold value is set high. As a result, it becomes difficult for the driving force control to be continuously performed in the high load region, the rise in the exhaust gas temperature can be suppressed, and the exhaust catalyst is protected.

According to the fourth aspect, the slip control threshold value is set high when the shift lever is selected to the fixed range. For example, the shift lever can be operated particularly in a high load region. In the case where the L range fixed to the first speed, which is highly likely to be selected, is selected, the slip control threshold value is set high. As a result, it becomes difficult for the driving force control to be continuously performed in the high load region, and it is possible to suppress an increase in the exhaust gas temperature, thereby protecting the exhaust catalyst.

As described above, the slip control threshold value is set high in a situation where the vehicle easily enters the high load region.
When the range is selected, the slip control threshold value is set low. In this case, the driving force control can be appropriately performed while the slip ratio is low.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows a TCS controller 1 comprising a microcomputer or the like as a driving force control device,
A case is shown in which fuel injection cut control is performed by the engine controller 2 in response to a command from the S controller 1.

The engine 4 connected to the automatic transmission 6
The fuel injection amount, the ignition timing, and the like are controlled by the engine controller 2 according to the operation state. The engine controller 2 performs output control such as fuel injection cutoff in response to a driving force control request from the TCS controller 1.

A throttle 8 responsive to an accelerator pedal 7 is provided in an intake passage of the engine 4, and an opening TVO of the throttle 8 detected by an opening sensor 9 is provided.
Is sent to the TCS controller 1 and the AT controller 3.

On the other hand, the automatic transmission 6 is
The AT controller 3 controls the automatic transmission 6 so as to achieve a gear ratio according to the driving state of the vehicle such as the throttle opening TVO and the vehicle speed.

The automatic transmission 6 is of an FR type connected to the rear wheels RR, RL.
RR is a driving wheel, and left and right front wheels FL and FR are driven wheels.

The TCS controller 1 includes wheel speed sensors 10FR, 10F for detecting the rotation speed of each wheel or axle.
L, 10RR, and 10RL are input, respectively. The TCS controller 1 determines each of these wheel speeds V _WFR ,
Based on V _WFL , V _WRR , and V _WRL , a slip ratio S of the driving wheel is calculated based on the speed ratio between the driving wheel and the driven wheel as described later.

Further, the TCS controller 1 is input a signal indicating the shift lever position from the shift lever 5 sets the slip control threshold S _L corresponding to the inputted shift lever position. As shown in the slip control threshold S _L is 4, as the shift lever position is the low speed side, the more becomes in other words the high load side, it is set to a larger value as the vehicle speed increases.

[0029] When the slip ratio S of the drive wheel is greater than the slip control threshold S _L, the engine controller 2
To reduce the output of the engine 4 by cutting the fuel injection to some of the cylinders. At this time, the torque reduction effect may be further enhanced by combining ignition timing control and the like in addition to the fuel injection cut.

Here, an example of the driving force control performed by the TCS controller 1 is shown in a flowchart of FIG. 2, and the driving force control will be described in detail below with reference to this flowchart. The control based on this flowchart is executed every predetermined time.

First, in step S11, the TCS controller 1 sets the shift lever position and the wheel speed sensors 1
The output of 0FR to 10RL is read and the speed V of each wheel is read.
_{Find WFR} , V _WFL , V _WRR , V _WRL .

In step S12, the average speed V of the driven wheels
_WF is determined from the average value of the wheel speeds V _WFR and V _WFL of the front left and right wheels FR and FL, and in step S13, the average speed V _WR of the drive wheels is similarly calculated as the wheel speed V _WRR and V of the left and right rear wheels RR and RL.
Obtain from _WRL . The average speed V _{WF of} the driven wheel and the average speed V _WR of the drive wheel are obtained by the following equations.

V _WF = (W _FR + W _FL ) / 2 V _WR = (W _RR + W _RL ) / 2 In step S14, the driving wheels are calculated based on the average speed V _{WF of} the driven wheels and the average speed V _WR of the driving wheels. Is determined.
The slip ratio S is obtained by the following equation.

[0034] _{S = (V WR -V WF)} / V WF Next, in step S15, sets the slip control threshold S _L corresponding to the shift lever position. As described above, the slip control threshold value _SL is set larger as the shift lever position is in the lower speed range, and is set so as to increase as the vehicle speed increases. As a result, when the shift lever is selected to the L range or the two range, a larger slip control threshold value _SL is set than when the D range or the like is selected. That is, in this case, the driving force control is not permitted up to the region where the slip ratio is large.

Then, in step S18, step S
It compares the slip control threshold S _L which is set in the slip ratio S and step S15 obtained in 14, when the slip ratio S is greater than the slip control threshold S _L, the driving force control is permitted Then, the process proceeds to step S19 to perform driving force control (fuel injection cut control). Conversely, when the slip ratio S is smaller than the slip control threshold S _L, the routine ends as the driving force control is not permitted.

Next, the operation will be described.

In this embodiment, each wheel speed is detected by a wheel speed sensor attached to each wheel, and the slip ratio of the drive wheel is calculated based on the detection result. Further, a slip control threshold value is set in accordance with the shift lever select position, and the slip control threshold value is set to be larger as the low speed range is selected.

Then, the slip ratios of these drive wheels are compared with the slip control threshold value, and when the slip ratio is larger than the slip control threshold value, fuel injection to some cylinders is cut to reduce the engine output. Driving force control is performed.

When the driving force control is performed by the fuel injection cut, the oxygen concentration in the exhaust gas increases, and the unburned gas reacts to increase the temperature of the catalyst. In particular, this tendency becomes stronger in the high load region, but since the slip control threshold value is set to a large value when the L range or the 2 range that is likely to be operated in the high load region is selected. Accordingly, it is possible to reduce the frequency of performing the fuel cut to a part of the cylinder, thereby preventing heat loss and deterioration of the exhaust catalyst.

On the other hand, when the high-speed stage in the D range where the possibility of operation in the high load region is low is selected, the slip control threshold value is set small. Driving force control is performed, and good driving force control can be performed.

Although the slip control threshold value is set larger as the shift lever is selected to the lower speed range, it may be set larger especially when the fixed range is selected.

Although the slip control threshold value is set so as to increase linearly in proportion to the vehicle speed, the setting of the slip control threshold value is not limited to this. It may be changed in a curved line.

Alternatively, when a predetermined slip control threshold value is exceeded, the driving force control may be performed irrespective of the vehicle speed or the shift lever select position. In this case, the driving force control is performed more than the protection of the exhaust catalyst. Priority is given to improving the stability of the vehicle.

The setting of the slip control threshold value is not limited to the one shown in the present embodiment, but is set to an appropriate value according to the operating conditions so that both the protection of the exhaust catalyst and the control of the driving force are sufficiently effective. You.

Although the slip control threshold value is set according to the shift lever position, the engine load is detected instead of the shift lever select position, and the slip control threshold value is set large in a high load region. The same operation and effect can be obtained in this case.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a driving force control device according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating an example of control performed by a TCS controller.

FIG. 3 is a graph showing a relationship between a driving wheel speed and an engine speed.

FIG. 4 is a graph showing a relationship between a slip control threshold value set according to a shift lever position and a vehicle speed.

FIG. 5 is a graph showing a state of fuel injection cut during conventional driving force control.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 TCS controller 2 Engine controller 4 Engine 5 Shift lever 6 Automatic transmission 10FR, 10FL, 10RR, 10RL Wheel speed sensor

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI F02D 41/02 330 F02D 41/02 330C 45/00 345 45/00 345G

Claims (4)

[Claims] 1. A vehicle driving force control device having an automatic transmission, comprising: a slip ratio calculating means for calculating a slip ratio of a driving wheel; and a driving force when the calculated slip ratio exceeds a slip control threshold value. Driving force control permission determining means for permitting control, and means for stopping fuel supply to some cylinders when driving force control is permitted;
And a slip control threshold value setting means for setting the slip control threshold value large when the engine is in a high load region. 2. A vehicle driving force control device having an automatic transmission, comprising: a slip ratio calculating means for calculating a slip ratio of a driving wheel; and a driving force when the calculated slip ratio exceeds a slip control threshold value. Driving force control permission determining means for permitting control, and means for stopping fuel supply to some cylinders when driving force control is permitted;
A vehicle driving force control device comprising: means for detecting a selected position of a shift lever; and a slip control threshold value setting means for setting a slip control threshold value according to the selected position of the shift lever. 3. The vehicle driving force control device according to claim 2, wherein the slip control threshold value is set to increase as the shift lever is selected to a lower speed range. 4. The vehicle driving force control device according to claim 2, wherein the slip control threshold value is set to be large when the shift lever is selected to a fixed range.