JPH0492729A - Driving force control device for vehicle - Google Patents

Abstract

PURPOSE:To suppress combustion of unburnt fuel in a catalyst by shifting up the speed of an automatic transmission to the high speed gear side so that the number of resolutions of an engine is prevented from an increase to a value higher than a given value when the feed of fuel is cut to suppress the occurrence of a drive wheel slip. CONSTITUTION:A running state detecting means (a), a number of revolutions of engine detecting means (b), and a slip ratio computing means (c) to compute a slip ratio between the drive wheel of a vehicle and a road surface are provided. Based on a running state, a fundamental feed amount of fuel is computed by a computing means (d). When the number of revolutions of an engine exceeds a given value, a fundamental feed amount is increased for correction by means of an increase correction means (e). A fuel feed means (g) to feed fuel to an engine is controlled according to an output from a fuel feed cut means (f) to cut the feed of fuel at each cylinder based on the magnitude of the slip ratio. When the number of revolutions of an engine exceeds a given value and fuel feed cut is commanded, a speed is shifted up to the high speed gear side by means of a shift up means (h).

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a driving force control device for a vehicle such as an automobile, and more particularly to a driving force control device for a vehicle that performs traction control of a vehicle.

(Prior Art) In recent years, there has been a trend in which not only engines but also vehicles are required to have higher fuel economy and drivability. From this point of view, microcomputers and the like are being used to more precisely control the running of a vehicle, and among these, the traction control system (Te3) for vehicles is attracting attention.

An example of a conventional vehicle driving force control device that performs Te3 is the one described in Japanese Patent Application Laid-open No. 8436/1983. This device detects the rotational speed of the driving wheels and non-driving wheels to calculate the slip ratio between the driving wheels and the road surface, and when the slip ratio is larger than the set value, some cylinders (
By supplying fuel only to the remaining cylinders (hereinafter referred to as "partial cylinder cut cylinders") (so-called partial cylinder cut cylinders), the driving force is quickly reduced to avoid drive wheel slippage in a responsive manner.

On the other hand, when the engine rotates at high speeds, it is necessary to cool the heat-receiving section by putting extra fuel into the cylinder to prevent the combustion chamber from overheating. There is a technique for creating a so-called rich mixed texture state.

(Problem to be Solved by the Invention) Here, we will discuss a technology for converting the conventional air-fuel ratio into a lynch mixture and a vehicle driving force control device that suppresses drive wheel slip by cutting fuel supply to some cylinders. In this case, unburned fuel is discharged from cylinders where fuel supply is not cut, while oxygen-containing intake air remains at high temperature from cylinders where fuel supply is cut. It is emitted as exhaust gas. Therefore, when the exhaust system is provided with a catalyst device, there is a problem that unburned fuel and oxygen are mixed and combusted within the catalyst device, resulting in an increase in temperature and deterioration of the performance of the catalyst.

Furthermore, on a road surface with an extremely low coefficient of road friction, such as an icy road, even if all cylinders are cut off from fuel, the slip of the drive wheels may still increase.

The present invention was made by focusing on these problems.
When cutting fuel supply to suppress drive wheel slip, the automatic transmission is configured to shift and amplify the gears so that the engine speed does not exceed a predetermined value. It is an object of the present invention to provide a vehicle driving force device that can suppress combustion of fuel in a catalyst, prevent performance deterioration of the catalyst, and improve the effect of suppressing drive slip.

(Means for Solving the Problems) In order to achieve the above-mentioned problems, the present invention provides an operation method for detecting the operating state of a multi-cylinder engine having an exhaust catalyst in the exhaust system, as shown in FIG. state detection means a;
The engine rotation speed detection means detects the rotation speed of the engine, the slip ratio calculation means C calculates the slip ratio between the driving wheels of the vehicle and the road surface, and the basic supply amount of fuel is calculated based on the driving condition. a basic supply amount calculating means d for calculating;
an increase correction means e for increasing the basic supply amount when the rotational speed of the engine exceeds a predetermined value; and a fuel supply for instructing the fuel supply to each cylinder based on the magnitude of the pick-up and drop ratio. cut command means f; and fuel supply means g for supplying fuel to the engine according to the outputs of the increase correction means and the fuel supply cut command means, and when the rotation speed of the engine is equal to or higher than a predetermined value and the fuel supply means The present invention is characterized in that it includes shift amplifier means h for shifting up the gear stage to a high gear side when a supply cut is commanded.

(Function) In the present invention, when the engine speed is equal to or higher than a predetermined value, the magnitude of the slip ratio exceeds a predetermined value, and a fuel supply cut to a specific cylinder is commanded, the gear of the transmission is shifted to a high gear. Since the engine is shifted up to , the engine speed is suppressed to a predetermined value or less, and no fuel increase correction is performed. For this reason,
Even if a fuel supply cut is continuously commanded in response to slip, less unburned fuel is exhausted to the exhaust system, less combustion occurs in the catalyst device, and a temperature rise in the catalyst is suppressed.

Furthermore, by shifting the gear position of the transmission toward a higher gear, the effect of suppressing drive slip is further increased.

(Example) Embodiments of the present invention will be described below based on the drawings.

2 to 5 are explanatory diagrams showing one embodiment of the vehicle driving force control device according to the present invention, which is applicable to a front wheel drive vehicle in which left and right front wheels are driving wheels and left and right rear wheels are driven wheels (driven wheels). This is an example of application.

First, the configuration will be explained. In FIG. 2, 1 is a six-cylinder engine for driving the vehicle. Intake air is supplied from an air cleaner (not shown) through an intake pipe and a throttle chamber to each cylinder 2 from each branch of the intake manifold, and fuel is injected by a throttle chamber (not shown) and an injector (fuel supply means) 4. mixed with inhaled air. Each cylinder 2 is equipped with a spark plug, and a high-pressure pulse is supplied to the spark plug from a distributor at a predetermined timing. The air-fuel mixture in the cylinder is ignited and exploded by the discharge of the ignition plug, and becomes exhaust gas, which passes through the exhaust pipe 5 into the catalytic converter 6, where harmful components in the exhaust gas are purified by a three-way catalyst, and then exhausted to the outside. The power of the engine 1 is transmitted to a drive shaft of the vehicle via a transmission, and drives drive wheels 11 and 12.

The intake air device is detected by an air flow meter.
Controlled by a throttle valve in the throttle chamber. The fully closed position of the throttle valve is detected by a throttle valve switch, and the crank angle of the engine 1 is detected by a crank angle sensor (engine speed detection means) 8 built into the distributor. The temperature of the cooling water of the engine 1 is detected by a water temperature sensor. The oxygen concentration in the exhaust gas is detected by an oxygen sensor. The air flow meter, throttle valve switch, water temperature sensor, and oxygen sensor constitute the operating state detection means 10.

The slip rate S between the driving wheels of the vehicle and the road surface is determined by the rotation speed sensor IIA of the left front wheel 11 which is the driving wheel, the rotation speed sensor 12A of the right front wheel 12, and the rotation speed sensor of the left rear wheel 13 which is the driven wheel. 13A and the rotation speed sensor 14A of the right rear wheel 14.

The signals from each of the above sensors 8.10 and IIA-14A are
The signal is input to the control unit 16, converted into a voltage by the F/V converter 17, then converted into digital data by the A/D converter 18, and input to the CPU 19. The control unit 16 has functions as a slip ratio calculation means, a basic supply amount calculation means, an increase correction means, and a fuel supply cut command means, and is mainly composed of a microcomputer. The control unit 16 performs engine cylinder control, fuel supply control, and vehicle traction control based on each input signal.

In FIG. 2, the signal from the crank angle sensor 8 is counted by a counter by the operation of a timer built in the control unit 16, and a signal corresponding to the number of inputs per unit time is sent to the CPU 1 as an engine rotation speed signal.
9 is input. The CPU 19 sends and receives signals to and from a built-in memory, and calculates the basic supply amount V of fuel suitable for the operating condition based on the signals from the various sensors, determines the timing to supply fuel to each cylinder, and controls the engine. When the rotational speed becomes equal to or higher than a predetermined value, an increase correction amount for the basic fuel supply amount V is calculated, and the calculation result is output to the fuel supply control unit 21.

A reference angle signal from the crank angle sensor 8 is also input to the fuel supply control unit 21, and the fuel supply control unit 21 controls the basic supply amount of fuel in accordance with the ignition timing, and also controls the engine speed at a predetermined speed. When the value is greater than or equal to the value, injection pulses C1 and C2 are outputted to supply the increased fuel supply amount to each cylinder 2 of the engine 1 at a predetermined timing. The air-fuel mixture in each cylinder 2 of the engine 1 is ignited by discharge from the spark plug.

Further, the control unit 16 controls a third rotation speed sensor (to be described later) based on signals from rotation speed sensors IIA to 14A of each wheel.
According to the traction control (control law) shown in the figure, the slip state of the left front wheel 11 and the right front wheel 12, that is, the magnitude relationship between the slip rate S and the first set value S0 and the second set value S1, which are predetermined values, is determined, The number of cylinders to which fuel supply should be cut is selected based on the magnitude of the slip rate S, and if the slip rate S exceeds a predetermined value S0, the number of cylinders to which fuel supply is to be cut is selected based on the command from the command means. (This example shows the case of 3 cylinders or 6 cylinders)
control signals C3 and C4 instructing to cut the fuel supply to the cylinder 2 are transmitted to the cut means 23, and the cut means 23 transmits the control signals C3 and C4 instructing the cut of fuel supply to the cylinder 2 from the fuel supply control unit 21 to each cylinder 2.
The injection pulses C1 and C2 output to the engine are cut to prevent fuel from being supplied.

The control unit 16 controls the A/T control unit (i.e., automatic transmission control unit ) 25, a shift-up signal C9 is transmitted to command the shift-up of the transmission 7 to the high-speed gear side.

The A/T control unit 25 outputs an output to cause the transmission 7 to shift up to a high gear.

Next, the effect will be explained.

The vehicle traction control performed by the control unit 16 will be explained. This routine is executed according to the flowchart shown in FIG. This is a fixed-time interrupt process driven at a predetermined cycle by an operating system (not shown).

First, in step S1, it is determined whether or not it is the first control cycle after engine startup, and if YES, step S2
Execute initialization by initializing each variable with . If it is determined in step S1 that it is not the first control cycle (No), the process moves to step S3. Next, in step S3, the detected actual rotation speed vyt of the left front wheel 11, rotation speed VFR of the right front wheel 12, rotation speed VRL of the left rear wheel 13, and rotation speed V■ of the right rear wheel 14 are read. In step S4, the front wheel average value ■ is calculated according to the following formula ■, and the rear wheel average value ■ is calculated according to the following formula ■, VF = (VFL + VFR) / 2 ...
・■V+i = (VRL+VIIR) / 2
....■ In step S5, the pickpocket/knob ratio S of the drive wheel is calculated according to the following formula 〇.

s= (VF -v*)/VF ・・・・・・■In step 6, the slip rate S is compared with a first set value s, which is a predetermined value (for example, 5o-0,1>), and the comparison is made. If the result is less than the first set value S. (S<S,) and NO,
It is determined that no slip has occurred, and in step S7,
The fuel supply to cylinder 2 is brought into a normal state, that is, the fuel is supplied to cylinder 6, and the transmission is shifted to a normal speed. If the comparison result in step S6 is YES with the first set value being 30 or more, then the second set value S1 (for example, S+ = 0.2) which is a predetermined value is further determined in step S8.
The comparison result is the second set value 82 or more (S≧S
+), it is determined that a large slip has occurred, and in step S9, control signals C1 and C4 are sent to stop fuel supply to all cylinders 2 (cut fuel supply to 6 cylinders).
is output, and the process proceeds to step Sll. Also, step S8
If the comparison result is less than the second set value S (S<S,), No
If so, it is determined that the slip 7 is relatively small, and a control signal C3 or C4 is output to cut the fuel supply to three of the six cylinders.

In step Sll, the engine speed N is set to a predetermined value NO(
For example No = 3000 rpm, 30 per minute
00 times) or more, and if it is less than N0
When , that is, when the engine is not rotating at high speed, this routine ends.

YE when engine speed N is equal to or higher than the predetermined value N0 (N≧NO)
If S, it is determined that the engine is rotating at high speed,
In step S12, a shift amplifier signal C5 for instructing the transmission 7 to shift up to the high-speed gear side is transmitted to the A/T control unit 25, and the current routine is ended.

Based on the shift-up signal C3 from the control unit 16, the A/T control unit 25 causes the gear position of the transmission 7 to shift one step to the high gear side when the gear position of the transmission 7 is not at the highest speed position.

As a result, the engine speed N is increased to a predetermined value by the gear ratio of the shift amplifier, as shown in Fig. 4.
For example, the rotation speed is reduced from 3000 rpa+) to N1, and the driving force is reduced by this gear ratio.

(Conventionally, when the rotational speed N reaches about 400 rpm, the gear is shifted up to the high gear side.) On the other hand, the throttle opening of the engine 1 is almost constant, and if the driving wheels continue to slip, this The engine speed N gradually increases again in response to the throttle/nottle opening degree K, and when the engine speed N rises to No, the shift amplifier signal C5 is again
is transmitted, and the gear is further shifted up to a higher gear. This upshifting operation is repeated until the slip is reduced or the gear becomes the highest gear, and during this time the engine speed is maintained at the rotation speed N0 or lower. Therefore, no fuel increase correction is performed, and the air-fuel ratio of the air-fuel mixture does not reach the lynch mixture state.

Therefore, since the engine speed N is always in the fuel supply cuff OK (F/COK) region of the present invention shown in FIG.
Even if ) is implemented, the discharge of unburned fuel can be suppressed, the temperature rise of the catalyst can be suppressed, deterioration of catalyst performance can be prevented, and the durability of catalyst performance can be improved.

Furthermore, at the time of drive slip, the gear stage is shifted up to the high gear side, thereby reducing the drive torque of the drive wheels, so that the effect of suppressing drive slip can also be improved.

In addition, in the said Example, the case where the driving wheel is a front wheel was demonstrated, but in this invention, it is not limited to this. Of course, the drive wheels may be rear wheels, or may be a four-wheel drive system with front and rear wheel drive.

Moreover, although the case where the fuel supply cut is executed for each three cylinders of a six-cylinder engine has been described, the present invention is not limited to this, and it goes without saying that the fuel supply cut may be executed for one cylinder at a time.

(Effects) As described above, according to the present invention, when cutting fuel supply to suppress drive wheel slip, the engine speed is
By configuring the automatic transmission to shift amplify gears toward higher gears, it is possible to suppress combustion of unburned fuel in the catalyst, suppress temperature rise, and prevent deterioration of catalyst performance, as well as reduce drive torque. The inhibitory effect can also be improved.

[Brief explanation of the drawing]

Figures 1 to 5 are diagrams showing one embodiment of the present invention. Figure 1 is a diagram of its basic conceptual configuration, Figure 2 is an explanatory diagram showing its overall configuration, and Figure 3 is a flowchart of its main parts. FIG. 4 is a graph showing changes in engine speed N,
FIG. 5 is a graph showing the permissible range of fuel supply cut. 1...Engine, 2...Cylinder, 4...Injector (fuel supply means), 7...
...-Transmission, 8...Crank angle sensor (engine speed detection means), 10...Driving state detection means, 11...Left front wheel (drive wheel) , 12... Right front wheel (drive wheel), 16... Control unit, N...
・Engine speed, S...Slip ratio, ■-...Basic supply amount. Patent applicant: Nissan Motor Co., Ltd.

Claims (1)

[Scope of Claims] a) Operating state detection means for detecting the operating state of a multi-cylinder engine having an exhaust catalyst in an exhaust system; b) Engine rotation speed detection means for detecting the rotation speed of the engine; c) Vehicle d) a basic supply amount calculation means for calculating a basic supply amount of fuel based on the driving condition; and e) a rotation speed of the engine. an increase correction means for increasing the basic supply amount when the amount exceeds a predetermined value; f) a fuel supply cut command means for instructing a fuel supply cut for each cylinder based on the magnitude of the slip ratio; and g) the increase amount. and a fuel supply means for supplying fuel to the engine according to the output of the correction means and the fuel supply cut command means, h) the rotation speed of the engine is a predetermined value or more, and the fuel supply cut is commanded. 1. A vehicle driving force control device comprising: a shift-up means for shifting up a gear to a high-speed gear when the vehicle is in a high-speed gear position.