JPH0861108A - Vehicle driving force control device - Google Patents

Abstract

PURPOSE: To ensure good traction control by setting the longest duration of fuel cutoff based on the operating condition of an engine, and terminating the fuel cutoff when the fuel cutoff is continued for the longest duration of fuel cutoff. CONSTITUTION: An engine operating condition detecting means 1 for detecting the operating condition of an engine, a driving wheel rotation detecting means 2 for detecting the driving wheels, a slip rate calculating means 3 or calculating the slip rate based on the rotation of the driving wheels, and a torque down signal outputting means 4 for calculating the torque down signal based on the slip rate, are provided. Further, based on the torque down signal, the fuel cutoff of specified cylinders is performed by a torque down control means 5, and based on the operating condition of the engine, the longest duration of the fuel cutoff is set by a longest duration setting means 6. When the fuel cutoff is continued for the longest duration of fuel cutoff, the fuel cutoff is forcedly terminated by a fuel cutoff duration control means 7.

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 a vehicle such as 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 vehicle driving force control device,
For example, there are those described in JP-A-4-295146 and 1-227830.

In these devices, the rotational speeds of the driving wheels and the non-driving wheels are detected to calculate the slip ratio between the tire and the road surface. When the slip ratio is larger than a set value, a torque down request based on the slip ratio is required. By cutting the fuel of a predetermined number of cylinders of the engine in accordance with the above, 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, It has improved performance.

By the way, when the fuel is cut, the fresh air from the fuel cut cylinder and the exhaust gas containing unburned components from the cylinder not cut the fuel enter the catalyst of the exhaust system,
Depending on the conditions, the temperature of the catalyst may rise above an allowable level due to combustion, which may lead to deterioration of the catalyst.

Therefore, by limiting the duration of the fuel cut and setting the prohibition time after the fuel cut, even if the fuel cut control is repeated as shown in FIG. We try not to exceed the allowable level.

[0007]

However, if the duration of fuel cut is limited in this way, torque reduction may not be performed as required.

That is, in the high engine speed and high load range,
Since the exhaust temperature is high, shortening the fuel cut duration will prevent the catalyst temperature from exceeding the allowable level, but if the fuel cut duration is shortened in the low rotation speed, low load range, etc. Although the temperature does not rise so much,
Depending on the duration, the fuel cut may have to be ended midway.

If the duration is set according to the temperature condition of the catalyst in the high rotation and high load range, the time during which the fuel cut cannot be performed increases in the actual traveling operation range, and as a result, the traction control system This will result in performance degradation.

An object of the present invention is to solve the above problems by properly setting the duration of fuel cut.

[0011]

A first invention is, as shown in FIG. 1, an engine operating condition detecting means 1 for detecting an operating condition of an engine, and a drive wheel rotating state detecting means for detecting a rotating state of a drive wheel. 2, a slip ratio calculating means 3 for calculating a slip ratio based on the rotation state, a torque down signal output means 4 for outputting a torque down signal of the engine based on the slip ratio, and a torque down signal based on the torque down signal. A torque down control means 5 that cuts fuel in a predetermined cylinder of the engine, a longest duration setting means 6 that sets the longest duration of fuel cut based on operating conditions of the engine, a longest duration of the fuel, A fuel cut time control means 7 for forcibly ending the fuel cut when the cut continues.

According to a second aspect of the invention, the longest duration setting means 6 makes the longest duration longer in the low rotation and low load region of the engine and shortens the longest duration in the high rotation and high load region.

A third aspect of the invention is provided with intake control means 8 for restricting intake air of the engine based on the torque down signal.

[0014]

According to the first aspect of the invention, the fuel in the predetermined cylinder of the engine is cut and the torque is reduced in accordance with the torque reduction request. However, the maximum duration of the fuel cut is set based on the operating condition of the engine. Therefore, the time during which the fuel can be cut increases without the temperature of the exhaust system catalyst exceeding the allowable temperature.

In the second aspect of the invention, since the longest duration of fuel cut is set longer in the low rotation and low load region of the engine, the time during which fuel can be cut is sufficiently increased and the exhaust temperature is high and high rotation and high load. Since the maximum duration of fuel cut is shortened in the region, the temperature of the exhaust system catalyst is properly prevented from rising above the allowable temperature.

In the third aspect of the invention, since the intake air is throttled together with the fuel cut, the torque can be quickly reduced and the fuel cut time can be shortened.

[0017]

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

As shown in FIG. 2, reference numeral 20 denotes an engine for driving a vehicle, and intake air is supplied from an air cleaner 21 to an 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, becomes exhaust gas, and the harmful components in the exhaust gas are cleaned by the three-way catalyst in the catalytic converter 26 through the exhaust pipe 25 and discharged to the outside. .

The power of the engine 20 is transmitted from the transmission 27 to the drive wheels 28 via the drive shaft of the vehicle.

The throttle chamber 23 has a throttle valve 30 and a T which are opened and closed by an accelerator pedal.
A throttle valve 31 for CS is installed. The opening of the throttle valve 30 is detected by a throttle opening sensor 32, and the TCS throttle valve 31 is connected to an actuator 33.

The flow rate of intake air is detected by an air flow meter 34, and the rotation speed of the engine 20 is detected by a 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. Catalytic converter 26
The catalyst bed temperature of 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 non-drive wheels 41 is detected by the non-drive wheel speed sensor 42. In this case, the average rotational speeds of the left and right drive wheels 28 and the left and right non-drive 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.

The fuel injection control is performed by detecting the detected intake air amount Q.
The basic injection amount Tp is calculated based on a and the engine speed N as follows: Tp = K · Qa / N (1) where K: 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) However, K _TW ; Water temperature increase correction coefficient K _AS ; Start-up and start-up increase correction coefficient K _AI An increase correction coefficient after idle K _ACC ; an acceleration correction coefficient K _DEC ; a deceleration correction coefficient K _FC ; a fuel cut correction coefficient T _S ; a 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.

Next, the traction control will be described with reference to FIG.
A description will be given based on the flowchart of FIG.

First, in steps 1 and 2 of FIG.
The driving wheel speed (average value of left and right) V _DW and the non-driving wheel speed (average value of left and right) V _PW are read, and the slip ratio S is calculated in step 3.
L 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, in step 5, the required torque down amount D is set according to the slip ratio SL, and In step 6, the torque reduction request flag TD is set to 1.

In FIG. 4, when the torque-down request flag TD = 1 in step 11, the torque-down request amount D is read in step 12, and in step 13, the torque-down control mode Mn corresponding to the torque-down request amount D is set. Read.

In step 14, the TCS throttle valve 31 is closed to a predetermined opening based on the torque down control mode Mn.

In step 15, the number FC of cylinders from which fuel is cut is read from the torque down control mode Mn.

Next, at step 16, it is judged whether or not the fuel cut is during the prohibit time, and if it is not during the prohibit time, the routine proceeds to step 17, where the fuel cut (F / C) of the number of cylinders FC is executed.

In FIG. 5, when the fuel cut is started, the engine speed N and the throttle opening TVO (or the basic injection amount Tp obtained by the fuel injection control) are read in step 21, and the engine speed N and the throttle are read in step 22. The maximum fuel cut duration FCMAX is determined based on the opening TVO.

This longest duration FCMAX is obtained by searching a map set to the characteristic as shown in FIG. 6, and when the engine speed N is high and the throttle opening TVO is large, it takes a small value to obtain the engine speed N. Is smaller and the throttle opening TVO is smaller, the larger the value.

In this case, in practice, data is given to the grid points of each area of the map, and the value within the area is obtained by plane interpolation of the values of the four grid points surrounding the area.

In step 23, the time JFCON after starting the fuel cut is measured.

When the fuel cut request is canceled before the fuel cut time JFCON reaches the longest duration FCMAX (torque down request flag TD =
0), and proceeds to steps 24 and 25 to end the fuel cut.

On the other hand, when the fuel cut time JFCON reaches the longest continuous time FCMAX, the routine proceeds from step 24 to step 26, and the fuel cut is ended (prohibited).

After the fuel is cut, a predetermined prohibition time,
Prohibit fuel cut.

With this configuration, when the drive wheels slip, the torque down request amount is set based on the slip ratio, and the TCS throttle valve 3 is operated according to the torque down control mode corresponding to the torque down request amount.
1 is closed to a predetermined opening degree, and the fuel from the fuel injector 24 of a predetermined cylinder is cut.

Therefore, the torque of the engine is quickly reduced, and the slip is suppressed. When the slip is suppressed, the fuel cut is ended and the TCS throttle valve 31 is fully opened.

On the other hand, when the slip ratio is large and is not suppressed, the TCS throttle valve 31 remains closed,
If the fuel cut is continued for the longest duration,
Fuel cut is ended.

In this case, as the engine speed is low and the load is low, the maximum duration of fuel cut is set longer as shown in FIG.

Therefore, the fuel cut is continued without concern that the temperature of the catalyst exceeds the allowable level in the low rotation and low load range where the exhaust gas temperature is low, and by the continuation, the slip is appropriately suppressed.

Further, when the engine speed and load are high, the maximum duration of fuel cut is set to be short as shown in FIG. 8. Therefore, in the high rotation and high load range where the exhaust temperature is high, the catalyst temperature is at an allowable level. Is reliably prevented.

Thus, with respect to the engine operating conditions,
You can set an appropriate fuel cut duration to ensure good traction control.

When the torque is reduced, the TCS throttle valve 31 is driven to be closed together with the fuel cut, so that the slip can be effectively suppressed by the fuel cut for a short time.

FIGS. 9 and 10 show another embodiment.
The maximum fuel cut duration FCMAX is set in the three-dimensional plane.

This is to improve the connection of the maximum duration FCMAX. As shown in FIG. 9, when the fuel cut is started, in step 31, the engine speed N and the throttle opening TVO (or the basic value determined by the fuel injection control). Injection amount T
p) is read, and in step 32, based on the engine speed N and the throttle opening TVO, 3 based on the data of FIG.
Longest duration FCM of fuel cut using three-dimensional curved surface formula
Determine AX.

At step 33, the time JFCON after the start of fuel cut is measured.

When the fuel cut request is exhausted before the fuel cut time JFCON reaches the maximum duration FCMAX (torque down request flag TD =
0), the process proceeds to steps 34 and 35 to end the fuel cut.

On the other hand, when the fuel cut time JFCON reaches the longest continuation time FCMAX, the routine proceeds from step 34 to 36 to end (prohibit) the fuel cut.

In this way, the longest duration can be set with good continuity with respect to changes in operating conditions.

[0056]

As described above, according to the first aspect of the present invention, the engine operating condition detecting means for detecting the operating condition of the engine, the drive wheel rotating state detecting means for detecting the rotating state of the drive wheels, and this rotating state. Based on the slip ratio, a torque down signal output means for outputting a torque down signal of the engine based on the slip ratio, and a fuel for a predetermined cylinder of the engine based on the torque down signal. Torque down control means to cut, longest duration setting means to set the longest duration of this fuel cut based on the operating conditions of the engine, and its longest duration, if the fuel cut continues, fuel cut Since the fuel cut time control means for forcibly ending is provided, the temperature of the exhaust system catalyst does not exceed the allowable level and the fuel cut is accurately performed. For example, it is possible to ensure a good traction control.

According to the second aspect of the present invention, the maximum duration of fuel cut is set longer in the low rotation and low load region of the engine and shortened in the high rotation and high load region. It is possible to reliably prevent the temperature of the system catalyst from rising above an allowable level, and improve the performance of traction control.

According to the third invention, together with the fuel cut,
Since the intake air is throttled, the torque can be reduced quickly and the fuel cut time can be shortened.

[Brief description of drawings]

FIG. 1 is a configuration diagram of the present invention.

FIG. 2 is a configuration diagram of an embodiment.

FIG. 3 is a flowchart of torque down control.

FIG. 4 is a flowchart of torque down control.

FIG. 5 is a flowchart of torque down control.

FIG. 6 is a characteristic diagram of the longest duration of fuel cut.

FIG. 7 is a timing chart of torque down control.

FIG. 8 is a timing chart of torque down control.

FIG. 9 is a flowchart of another embodiment.

FIG. 10 is a three-dimensional characteristic diagram of the longest duration of fuel cut.

FIG. 11 is a timing chart of conventional torque down control.

[Explanation of Codes] 20 Engine 23 Throttle Chamber 24 Fuel Injector 25 Exhaust Pipe 26 Catalytic Converter 28 Drive Wheel 30 Throttle Valve 31 TCS Throttle Valve 32 Throttle Opening Sensor 33 Actuator 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 Non-drive wheel 42 Non-drive wheel speed sensor 45 Control unit

Claims (3)

[Claims] 1. An engine operating condition detecting means for detecting an operating condition of an engine, a drive wheel rotating state detecting means for detecting a rotating state of a drive wheel, and a slip ratio calculating means for calculating a slip ratio based on the rotating state. A torque down signal output means for outputting a torque down signal of the engine based on the slip ratio; a torque down control means for cutting fuel of a predetermined cylinder of the engine based on the torque down signal; The maximum duration time setting means for setting the maximum duration time of the engine based on the operating conditions of the engine, and the maximum duration time, and the fuel cut time control means for forcibly ending the fuel cut when the fuel cut continues. A driving force control device for a vehicle, which is provided. 2. The longest duration setting means lengthens the longest duration in a low rotation and low load region of the engine and shortens the longest duration in a high rotation and high load region of the engine. Vehicle driving force control device. 3. The vehicle drive force control device according to claim 1, further comprising intake control means for restricting intake air of the engine based on the torque down signal.