JPH0849579A - Driving force controller for vehicle - Google Patents

Abstract

PURPOSE:To appropriately reduce torque so as to improve traction control performance by temporarily inhibiting fuel-cut, and setting the inhibition time according to a real fuel cut time and the operational condition of an engine after the fuel is cut by a torque down control means. CONSTITUTION:A slipping rate is calculated by a slipping rate calculation means 3 based on a operational conditions of driving wheels detected by a driving wheel rotational condition detection means 2 while a vehicle, runs and a torque down signal is output from a torque down signal output means 4 based on the slipping rate. The fuel cut is controlled by a torque down control means 5 based on the torque down signal and the output signal of an engine operational condition detection means 1. The fuel cut is temporarily inhibited by a fuel cut inhibition control means 6 after the fuel cut, and the inhibition time is set according to the real fuel cut time and the operational conditions of the engine.

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 setting the fuel cut duration (maximum time) and the prohibition time after the fuel cut, even if the fuel cut control is repeated as shown in FIG. Does not rise above an acceptable level.

[0007]

However, in this case, when the vehicle is actually traveling, slippage is avoided by torque reduction due to fuel cut, which is usually shorter than the duration, whereas the prohibition time after fuel cut is constant. Since it is set, the time during which fuel cut cannot be performed increases, and as a result, the performance of the traction control system deteriorates.

An object of the present invention is to set such a fuel cut inhibition time appropriately to solve such a problem.

[0009]

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. In a vehicle driving force control device including a torque down control means (5) for cutting fuel in a predetermined cylinder of an engine, fuel cut is temporarily prohibited after the fuel cut by the torque down control means (5), and A fuel cut prohibition control means 6 is provided for setting the prohibition time according to the actual fuel cut time and the engine operating conditions.

A second aspect of the present invention is an engine operating condition detecting means 1 for detecting an operating condition of an engine, a drive wheel rotating state detecting means 2 for detecting a rotating state of a drive wheel, and a slip ratio based on the rotating state. Slip ratio calculating means 3 for calculating
And 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 control means 5 for cutting fuel of a predetermined cylinder of the engine based on the torque down signal. In the vehicular driving force control device, the fuel cut is temporarily prohibited after the fuel cut by the torque down control means 5, and the prohibit time is the actual fuel cut time, the number of fuel cut cylinders, and the engine operation. A fuel cut prohibition control means 7 that is set according to the conditions is provided.

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.

[0012]

According to the first aspect of the invention, the fuel is cut in accordance with the torque down request, and after the fuel cut, the prohibition time corresponding to the actual fuel cut time and the operating condition of the engine, that is, the actual fuel cut time. The shorter the time, the shorter the fuel cut prohibition time.

In the second invention, similarly to the first invention, the shorter the actual fuel cut time is, the shorter the fuel cut inhibition time is, and the more the fuel cut inhibition time can be obtained.

In the third aspect of the invention, since the intake air is throttled at the same time as the fuel cut, the torque is quickly reduced and the fuel cut time is shortened.

[0015]

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, and 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 driven to close 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 if the fuel cut prohibition time is in progress. If it is not during the prohibition time, the routine proceeds to steps 17 and 18.

In step 17, the maximum fuel cut duration FCMAX is set based on the engine operating conditions.
In step 18, fuel cut for the number of cylinders FC (F / C)
Carry out.

In FIG. 5, when the fuel cut is started, in step 21, the fuel cut time JFCON is measured.

When the fuel cut request is exhausted before the fuel cut time JFCON reaches the longest duration FCMAX (torque down request flag TD =
0), the process proceeds from steps 22 and 23 to 24, and the fuel cut inhibition time JFCOFF is calculated by the following equation (4).

JFCOFF = JFCON / FCRATE (4) In this case, the maximum fuel cut prohibition time is set based on the engine operating conditions, and the prohibition time ratio is calculated from the fuel cut time JFCON with respect to the longest duration FCMAX. The fuel cut-on / off ratio FCRATE obtained by correcting the prohibition time ratio based on the longest prohibition time is obtained and calculated.

Here, since the requested prohibition time JFCOFF differs depending on whether the number of cylinders for fuel cut is small or large, the prohibition time ratio, that is, the fuel cut-on / off ratio FCR.
Different ATE.

In the case where the fuel cut is a small number of cylinders, assuming that the maximum fuel cut duration is A and the maximum prohibit time is B, the catalyst temperature rise allowable region and the NG region are as shown in FIG. The fuel cut-on / off ratio FCRATE is set to the prohibited time JFCOFF of the region. That is, when the fuel cut is in a small number of cylinders, the catalyst temperature rises quickly due to the fuel cut, and therefore, when the fuel cut is completed within the predetermined time C, the prohibition time is relatively lengthened.

When the maximum number of fuel cuts is A and the maximum inhibition time is B in the case where the number of fuel cuts is many, the catalyst temperature rise allowable region and NG region are as shown in FIG. The fuel cut-on / off ratio FCRATE is set to the prohibited time JFCOFF of the region. In other words, when the fuel cut is in a large number of cylinders, afterburning occurs in the catalyst. Therefore, when the fuel cut is the predetermined time D or more, the prohibition time is relatively long.

On the other hand, when the fuel cut time JFCON reaches the longest continuation time FCMAX, the routine proceeds from step 22 to step 26, 27 where the fuel cut is prohibited and the fuel cut prohibit time JFCOFF is set by the following equation (5). Calculate

JFCOFF = FCMAX / FCRATE (5) In this case, the inhibition time JFCOFF is the maximum inhibition time based on the engine operating conditions.

With this configuration, when the drive wheels slip, the torque down request amount D is set based on the slip ratio SL, and the TCS throttle is set according to the torque down control mode Mn corresponding to the torque down request amount D. The valve 31 is closed to a predetermined opening degree, and the fuel from the fuel injector 24 of a predetermined cylinder is cut off.

Therefore, the torque of the engine is quickly reduced, and the slip is suppressed.

When the slip is suppressed, the fuel cut is ended, the TCS throttle valve 31 is fully opened, and when the fuel cut is continued for the longest duration, the fuel cut is ended.

In this case, when the fuel cut is continued for the longest duration, the fuel cut is prohibited for the longest prohibited time after the fuel cut, but when the fuel cut is finished for a time shorter than the longest duration. After the fuel cut, the fuel cut is prohibited for the prohibition time set according to the actual fuel cut time and the operating condition of the engine.

That is, when the fuel cut is finished in a short time, the fuel cut inhibition time is shortened.

Therefore, when the fuel cut control is repeated, the time during which the fuel cut cannot be performed does not unnecessarily increase, and the slip is accurately maintained while keeping the catalyst temperature below the allowable level as shown in FIG. It is avoided in and the good traction control is secured.

Further, in this case, the temperature rising state of the catalyst is different between when the number of fuel cut cylinders is small and when the number of fuel cut cylinders is large, but proper prohibition times are set when the number of fuel cut cylinders is small and large. Since it is set, the temperature of the catalyst will not rise above the allowable level depending on the number of cylinders,
This keeps the catalyst in good condition.

On the other hand, when the torque is reduced, the TCS throttle valve 31 is driven to be closed together with the fuel cut.
Slip is effectively suppressed and fuel cut time is shortened.

FIGS. 9 and 10 show another embodiment.
Prohibition time J of fuel cut when the fuel cut is a small number of cylinders J
The calculation contents of FCOFF are shown.

Assuming that the longest duration of fuel cut is A and the longest inhibition time is B, the temperature rise allowable region and NG region of the catalyst are as shown in FIG. 10. In this case, the longest duration FCMAX.
The fuel cut-off time FC is set by setting the prohibition time ratio to three levels L, M and N based on the fuel cut time JFCON and correcting these prohibition time ratios based on the longest prohibition time.
RATE1, 2, 3 (FCRATE1 <2 <3) is obtained, and the inhibition time JFCOFF is calculated.

That is, as shown in FIG. 9, when the fuel cut is started, in step 31, the fuel cut time JFCON is measured.

When the fuel cut request is canceled before the fuel cut time JFCON reaches the maximum duration FCMAX (torque down request flag TD = in FIG. 3).
0), the process proceeds from steps 32, 33 to 34, and the fuel cut time EFCON is compared with a predetermined value a.

When the fuel cut time JFCON is larger than the predetermined value a, in step 35, the fuel cut prohibition time JFCOFF is calculated by the following equation (6).

JFCOFF = JFCON / FCRATE1 (4) When the fuel cut time JFCON is a predetermined value a or less,
The process proceeds to step 37 to compare with the predetermined value b.

When the fuel cut time JFCON is larger than the predetermined value b, the fuel cut inhibition time JFCOFF is calculated in step 38 by the following equation (7).

JFCOFF = JFCON / FCRATE2 (7) When the fuel cut time JFCON is a predetermined value b or less,
In step 40, the fuel cut inhibition time JFCOFF is calculated by the following equation (8).

JFCOFF = JFCON / FCRATE3 (8) On the other hand, the fuel cut time JFCON is the longest duration FC
When reaching MAX, the routine proceeds from step 32 to 42 and 43, where the fuel cut is prohibited and the fuel cut prohibition time JFCOFF is calculated by the following equation (9).

JFCOFF = FCMAX / FCRATE (9) In this case, the inhibition time JFCOFF is the longest inhibition time based on the engine operating conditions.

In this way, calculation of the fuel cut-on and off ratios FCRATE1, 2, 3 and the prohibition time JFC
OFF calculation can be performed easily.

Of course, the present invention can also be applied to the calculation of the fuel cut inhibition time JFCOFF when the fuel cut is performed in a large number of cylinders.

FIG. 11 and FIG. 12 show another embodiment, and show the contents of calculation of the fuel cut inhibition time JFCOFF when the fuel cut is a small number of cylinders.

Based on the fuel cut time JFCON with respect to the longest fuel cut duration FCMAX, the prohibit time ratio is set to a constant value when the fuel cut time is equal to or greater than a predetermined value, and 1 is set when the time is less than the predetermined value. Determine the prohibited time JFCOFF.

That is, as shown in FIG. 11, when the fuel cut is started, in step 51, the fuel cut time JFCON is measured.

When the fuel cut request is canceled before the fuel cut time JFCON reaches the maximum duration FCMAX (torque down request flag TD = in FIG. 3).
0), the process proceeds from steps 52, 53 to 54, and the following equation (1
The fuel cut inhibition time JFCOFF is calculated from 0).

JFCOFF = JFCON / FCRATE (10) This fuel cut-on / off ratio FCRATE is a value obtained by correcting a fixed prohibition time ratio based on the longest prohibition time.

Next, at step 55, the prohibited time JFCOF is set.
F is compared with the minimum prohibited time FCMIN, and the prohibited time is JFC
When OFF is longer than the minimum prohibition time FCMIN, J
FCOFF is prohibited time JFCOFF is minimum prohibited time F
When it is smaller than CMIN, FCMIN is set as the prohibition time.

On the other hand, when the fuel cut time JFCON reaches the maximum duration FCMAX, steps 52 to 5 are executed.
At 8 and 59, the fuel cut is prohibited, and the fuel cut prohibition time JFCOFF is calculated by the following equation (11).

JFCOFF = FCMAX / FCRATE (11) In this case, the inhibition time JFCOFF is the longest inhibition time based on the engine operating conditions.

In this way, the prohibited time JFCOFF
Is easier to calculate. Of course, the present invention can be applied to the calculation of the fuel cut inhibition time JFCOFF when the fuel cut is performed in a large number of cylinders.

When the fuel cut is for a small number of cylinders, the prohibition time JFCOFF is set for the fuel cut time JFCON.
The relationship may be set as shown in FIG. Further, in the case where the fuel cut is a large number of cylinders, the relationship between the fuel cut time JFCON and the prohibited time JFCOFF is shown in FIG. 14 or FIG.
You may set like 5.

[0072]

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. In a vehicle driving force control device provided with a torque down control means for cutting, a fuel cut is temporarily prohibited after the fuel cut by the torque down control means, and this prohibition time is set as an actual fuel cut time. Since the fuel cut prohibition control means that is set according to the engine operating conditions is provided, the fuel cut prohibition time is shortened, and the exhaust system catalyst Without degree exceeds the allowable level, it is performed accurate torque reduction by fuel cut,
The performance of traction control is improved.

According to the second aspect of the 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 the slip ratio based on this rotating state Slip rate calculating means for calculating, torque down signal output means for outputting a torque down signal of the engine based on the slip rate, and torque down control means for cutting fuel of a predetermined cylinder of the engine based on the torque down signal In the vehicle driving force control device including the above, while temporarily prohibiting the fuel cut after the fuel cut by the torque down control means, this prohibition time is set to the actual fuel cut time and the number of fuel cut cylinders. Since a fuel cut prohibition control means that is set according to the engine operating conditions is provided, the prohibition time that matches the number of fuel cut cylinders can be set. While maintaining the temperature state of the exhaust system catalyst more properly, accurately performing torque-down by the fuel cut, to improve the performance of the traction control.

According to the third invention, together with the fuel cut,
Since the intake air is throttled, the torque can be quickly reduced by cutting the fuel for a short time.

[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 prohibition time calculation.

FIG. 6 is a characteristic diagram showing a relationship between a fuel cut time and a prohibition time.

FIG. 7 is a characteristic diagram showing a relationship between a fuel cut time and a prohibition time.

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

FIG. 9 is a flowchart of another embodiment.

FIG. 10 is a characteristic diagram showing a relationship between a fuel cut time and a prohibition time.

FIG. 11 is a flowchart of another embodiment.

FIG. 12 is a characteristic diagram showing a relationship between a fuel cut time and a prohibition time.

FIG. 13 is a characteristic diagram showing a relationship between a fuel cut time and a prohibition time.

FIG. 14 is a characteristic diagram showing a relationship between a fuel cut time and a prohibition time.

FIG. 15 is a characteristic diagram showing a relationship between a fuel cut time and a prohibition time.

FIG. 16 is a timing chart of conventional torque down control.

[Explanation of symbols]

 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 bed sensor 40 Drive wheel speed sensor 41 Non-drive wheel 42 Non-drive wheel speed sensor 45 Control unit

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display area F02D 43/00 301 HK 45/00 345 G

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. And a torque down signal output means for outputting a torque down signal of the engine based on the slip ratio, and a torque down control means for cutting fuel of a predetermined cylinder of the engine based on the torque down signal. In the driving force control device, the fuel cut is temporarily prohibited after the fuel cut by the torque down control means, and the prohibit time is set according to the actual fuel cut time and the engine operating condition. A driving force control device for a vehicle, which is provided with prohibition control means. 2. 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 this rotating state. And a torque down signal output means for outputting a torque down signal of the engine based on the slip ratio, and a torque down control means for cutting fuel of a predetermined cylinder of the engine based on the torque down signal. In the driving force control device, the fuel cut is temporarily prohibited after the fuel is cut by the torque down control means, and the prohibit time is set to the actual fuel cut time, the number of fuel cut cylinders, and the engine operating condition. A driving force control device for a vehicle, which is provided with a fuel cut prohibition control means which is set in accordance therewith. 3. The vehicle driving force control device according to claim 1, further comprising intake control means for restricting intake of the engine based on the torque down signal.