JPH01153342A - Vehicle differential motion limiting control device - Google Patents

Abstract

PURPOSE:To prevent induction of spin by subtracting, for correction, an instruction value proportional to a drive wheel slip from the sum of instruction values which are in proportion to an accelerator opening degree and a difference in rotational speed between right and left drive wheels, so as to obtain a final differential motion limiting torque value. CONSTITUTION:A control means 3 in a differential motion limiting clutch means 1 uses a first component which is a sum of an instruction value increasing in proportion to accelerator opening degrees detected by a detecting means 201 and an instruction value increasing in proportion to differences in rotational speed between right and left drive wheels detected by a detecting means 201, and a second component which is an instruction value increasing in proportion to drive wheel slips detected by a detecting means 30, and uses a value which is obtained by subtracting, for correction, the second component from the first component, as a torque instruction value for limiting final differential motion. Thus, it is possible to reduce the possibility of induction of spin in various road surface conditions and drive conditions, to facilitate drift control.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a differential limiting control device for a vehicle that is used in a differential device of an automobile and controls differential limiting torque.

(Prior Art) Conventional differential limiting control devices for vehicles include, for example, Japanese Patent Laid-Open No. 103227/1983 (Patent Application No. 244677/1983) and Japanese Patent Laid-open No. 102320/1983 (Japanese Patent Application No. 59/1989). 22
3486) is known.

The former conventional device is a differential limiting control device for a vehicle that can control differential limiting torque, and in order to reliably control even in a sudden one-wheel slip situation, the differential limiting torque characteristic for the left and right drive wheel rotational speed difference is controlled. It has progressive characteristics.

The latter conventional device is a vehicle differential limiting control device that can control differential limiting torque, and uses large steering, large accelerator opening, and road surface μ below a predetermined vehicle speed to prevent the inner wheels from sticking when turning. When is high, the differential limiting torque is reduced.

(Problem to be Solved by the Invention) However, in the conventional device of the former, the differential limiting torque is generated in proportion to the rotational speed difference between the left and right driving wheels, and in the conventional device of the latter, Since the differential limiting torque is generated in proportion to the accelerator opening, even if the vehicle's yaw rate is too high during corner acceleration and causes a spin, it is possible to control only the rotational speed difference between the left and right drive wheels and the accelerator opening. By setting it as a control parameter, a high differential limiting torque continues to be applied, and as a result, there remains the problem that spin is easily induced.

(Means for Solving the Problems) The present invention has been made for the purpose of solving the above-mentioned problems, and to achieve this purpose, the present invention employs the following solving means.

The solution of the present invention will be explained with reference to the conceptual diagram of the claim shown in FIG. A differential limiting control device for a vehicle is provided with a clutch control means 3 that performs increase/decrease control of differential limiting torque based on a detection signal of the accelerator opening detection means 201 and left and right drive wheels as the detection means 2 Rotational speed difference detection means 202 and driving wheel slip detection means 203
The clutch control means 3 includes, as a first component, the sum of a command value that increases in proportion to the accelerator opening degree and a command value that increases in proportion to the rotational speed difference between left and right driving wheels, and The means is characterized in that the second component is a command value that increases in proportion to wheel slip, and the final differential limiting torque command value is a value obtained by subtracting and correcting the second component from the first component. .

(Function) During a steady turn with a large turning radius, the accelerator opening is low and there is little drive wheel slip, so the influence of the difference in rotational speed between the left and right drive wheels is greatest. For this reason, the differential limiting command value is determined based on the rotational speed difference between the left and right driving wheels.

Both the command value proportional to the accelerator opening degree and the command value proportional to the drive wheel slip are used to correct the differential limit command value in a stable direction that suppresses the increase in the rotational speed difference between the left and right drive wheels. It becomes difficult to induce spin depending on the situation.

In other words, when the driving force increases due to an increase in accelerator opening, the differential limiting torque is increased to suppress the increase in the rotational speed difference between the left and right drive wheels, and when the left and right drive wheels lose road grip and drive wheel slip increases, the differential limiting torque is increased. By lowering the dynamic limit torque, the increase in the rotational speed difference between the left and right drive wheels is suppressed.

During power slide driving, the driver depresses the accelerator and turns using the skidding of the drive wheels, so the difference in rotational speed between the left and right drive wheels is small, and the differential limit command value is determined based on the accelerator opening. be done.

Then, at the apex of the corner where the accelerator pedal is depressed, the differential limiting torque increases, suppressing the inside wheel slip, transitioning from understeer to oversteer (reverse steer characteristics), and the vehicle enters a drift state.

In this drift state, the final differential limiting command value is determined by subtracting the command value proportional to the drive wheel slip from the command value mainly based on the accelerator opening, so drift control becomes easy.

In other words, as drive wheel slip increases, the drive wheels lose road grip and drift control becomes difficult, so by reducing the differential limiting torque T in proportion to drive wheel slip, vehicle spin is suppressed and drift control becomes difficult. Ensure ease of use.

(Example) Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

In describing this embodiment, a differential limiting control device for a rear wheel drive vehicle equipped with a multi-disc friction clutch means operated by external hydraulic pressure will be taken as an example.

First, the configuration of the embodiment will be explained.

As shown in FIG. 2, the rear wheel drive type to which the differential limiting control device of the embodiment is applied has a left front wheel 10, a right front wheel 11. The differential gear 15 includes an engine 12, a transmission I3, a propeller shaft 14, a differential gear 15, a left drive shaft 16, a right drive shaft 17, a left rear wheel I8, and a right rear wheel I9. , a propeller shaft 14 on the drive input side and a drive shaft 16 on the drive output side.
．． A wet multi-disc friction clutch (differential limiting clutch means) 20 is provided between the left and right wheels 18 and 17 to limit differential movement between the left and right wheels 18 and 19.

Note that the wet multi-disc clutch 20 is engaged by control hydraulic pressure P from a hydraulic pressure generator 30, which is an external device.

As shown in FIG. 3, the differential limiting control device of the embodiment is as follows.
The input sensors 40 include a left front wheel rotation speed sensor 41, a right front wheel rotation speed sensor 42, a left rear wheel rotation speed sensor 43,
A right rear wheel rotation speed sensor 44 and an accelerator opening sensor 45 are provided, and a differential limiting control circuit 5 is provided as a control module.
0 is provided, and an electromagnetic proportional pressure reducing valve 60 is provided as a control actuator.

The left front wheel rotational speed sensor 41 and the right front wheel rotational speed sensor 42 are means for detecting the rotational speed of the left and right front wheels 10.11 which are non-driving wheels, and the sensor 4I detects the rotational speed of the left front wheel according to the left front wheel rotational speed NFL. The speed signal (nfl) and the sensor 42 output a right front wheel rotational speed signal (nfr) corresponding to the right front wheel rotational speed NFR.

The left rear wheel rotational speed sensor 43 and the right rear wheel rotational speed sensor 44 are means for detecting the rotational speed of the left and right rear wheels 18.19 which are drive wheels, and the left rear wheel rotational speed N is detected from the sensor 43.
The sensor 44 outputs a left rear wheel rotational speed signal (nrl) corresponding to the rotational speed of the left rear wheel, and a right rear wheel rotational speed signal (nrr) corresponding to the right rear wheel rotational speed NRR.

The accelerator opening sensor 45 is a sensor that outputs an accelerator opening signal (a) corresponding to the accelerator opening A.

The differential limiting control circuit 50 is a control circuit centered on an on-vehicle microcomputer, and includes an input interface circuit 51, a memory 52, a CPU (central processing unit) 53, and an output interface circuit 54.

A concrete block diagram of the differential limit control circuit 50 is shown in FIG. 4, which includes subtracters 501, 502, averagers 503, 504, and function generators 505, 506, .
507 and an adder/subtractor 508.

The electromagnetic proportional pressure reducing valve 60 is connected to the hydraulic pressure generator 30.
The hydraulic oil at the pump pressure, which is provided in the
This is a valve actuator that controls pressure to a control oil pressure P that is proportional to the magnitude of.

Furthermore, what is the control oil pressure P and the differential limiting torque T?

TOCP-g-n-r-E n: number of clutches r: clutch average radius E: pressure receiving area; differential limiting torque T is proportional to control oil pressure P.

Next, the operation of the embodiment will be explained.

First, the operational flow of the differential limiting control in the differential limiting control circuit 50 will be described with reference to the flowchart shown in FIG.

In step 100, each sensor 41.42°43.44
．． 45, the left front wheel rotation speed NFL, right front wheel rotation speed NFR, left rear wheel rotation speed NRL, right rear wheel rotation speed NRR, and accelerator opening degree A are read.

In step 101, the left and right drive wheel rotational speed difference ΔNrQ is calculated from the left rear wheel rotational speed NRL and the right rear wheel rotational speed NRR read in step 100.

Note that the calculation formula is ΔN r A = NRL - NRR.

In step 102, from the left front wheel rotation speed NFL, right front wheel rotation speed NFR, left rear wheel rotation speed NRL, and right rear wheel rotation speed NRR read in step lOO, the front and rear wheel rotation speed difference ΔNfr indicating drive wheel slip is calculated. is obtained by calculation.

Note that the calculation formula is as shown below.

ΔN f r='A (NRL+NRR) -'A (
NFL+NFR) In step 103, step 1
The differential side-limiting torque T1 is determined which is proportional to the left and right drive wheel rotational speed difference ΔNrβ obtained in step 01.

Note that this differential limiting torque T is determined by the function generator 5 in FIG.
As shown in the characteristic diagram of No. 05, it is obtained as a value that is linearly proportional to the increase in the rotational speed difference ΔNrβ between the left and right driving wheels.

In step 104, differential limiting torque T2 proportional to the accelerator opening degree A read in step 100 is determined.

Incidentally, this differential limiting torque T2 is calculated by the function generator 5 in FIG.
As shown in the characteristic diagram of No. 06, it is obtained as a value that is linearly proportional to the increase in accelerator opening A.

In step 105, a differential limiting torque T3 proportional to the front and rear wheel rotational speed difference ΔNfr obtained in step 102 is applied.
is required.

Incidentally, this differential limiting torque T3 is calculated by the function generator 5 in FIG.
As shown in the characteristic diagram of 07, the front and rear wheel rotational speed difference Δ
It is obtained as a value that is linearly proportional to the increase in Nfr.

In step 106, each differential limiting torque T, , T
2. The final differential limiting torque T is calculated from T.

The calculation formula for the final differential limiting torque T is as shown below.

T=T+10T2-T:1 In step 107, a signal (i) based on one command current value that provides the final differential limiting torque T is output.

Next, the effects during turning will be explained separately for steady turning with a large turning radius and power sliding.

(B) When making a steady turn with a large turning radius During a steady turning with a large turning radius, the accelerator opening degree A is low;
Furthermore, since the rotational speed difference ΔNfr between the front and rear wheels due to drive wheel slip is small, the influence of the rotational speed difference ΔNrJ2 between the left and right drive wheels is greatest. For this reason, the rotational speed difference between the left and right driving wheels ΔNrβ
The final differential limiting torque T is determined based on the current differential limiting torque T.

The differential limiting torque T2 is proportional to the accelerator opening A.
Also, the differential limiting torque T3, which is proportional to the front and rear wheel rotational speed difference ΔNfr, is adjusted to correct the final differential limiting torque T in a stable direction that suppresses the increase in the left and right driving wheel rotational speed difference ΔNrJ2, so that it can be adjusted in all road conditions, driving conditions, etc. This makes it difficult to induce spin.

That is, when the driving force increases due to an increase in the accelerator opening degree A, the differential limiting torque T is increased (T.

+T2), suppressing the increase in the left and right drive wheel rotational speed difference ΔNrJ2.

In addition, when the left and right drive wheels 18,19 lose road surface grip and drive wheel slip increases, the differential limiting torque T is lowered (T, -T3) to reduce the rotational speed difference ΔN between the left and right drive wheels.
Suppress the rise in r12.

(b) When driving on a power slide When driving on a power slide, the driver depresses the accelerator and turns using the sideslip of the drive wheels 18, 19, so the difference in rotational speed between the left and right drive wheels is Nr.
ff is small, and the differential limiting torque T due to the accelerator opening degree A
The final differential limiting torque T is determined based on 2.

Then, at the apex of the corner where the accelerator pedal is depressed, the differential limiting torque T increases, inner wheel slip is suppressed, understeer shifts to oversteer (reverse steer characteristics), and the vehicle enters a drift state.

In this drift state, the final differential limiting torque T is determined by subtracting the differential limiting torque T3, which is proportional to the front and rear wheel rotational speed difference ΔNfr, from the differential limiting torque T2, which is proportional to the accelerator opening degree A. Drift control becomes easier.

In other words, as drive wheel slip increases, the drive wheels lose their grip on the road surface and drift control becomes difficult, so by reducing the differential limiting torque T in proportion to the drive wheel sleeve, vehicle spin can be suppressed and drift control can be achieved. Ensure ease of use.

Although the embodiments of the present invention have been described above in detail with reference to the drawings, the specific configuration is not limited to these embodiments. include.

For example, in the embodiment, an electromagnetic proportional pressure reducing pulp is shown as an actuator, but an example in which an electromagnetic valve that opens and closes or the like may be used to perform hydraulic control by using a control signal as a duty signal may also be used.

Further, in the embodiment, an example was shown in which the differential limiting torque is obtained using a wet multi-disc friction clutch, but an example in which the differential limiting torque is obtained using a clutch such as an electromagnetic clutch or a brake may also be used.

Although the example in which the rotational speed difference between the front and rear wheels is used as drive wheel slip information has been shown, a drive wheel slip rate or a drive wheel slip ratio may also be used.

(Effects of the Invention) As explained above, in the differential limiting control device for a vehicle of the present invention, the clutch control means can control the command value that increases in proportion to the accelerator opening and the rotational speed difference between the left and right driving wheels. The first component is the sum of the command value that increases in proportion to the driving wheel slip, and the second component is the command value that increases in proportion to the drive wheel slip, and the second component is subtracted from the first component. This is a means for setting the corrected value as the final differential limiting torque command value, and has the accelerator opening degree and left and right drive wheel rotational speed difference as control human power information, and performs differential limiting control while suppressing drive wheel slip. This has the effect of making it difficult to induce spin under all road conditions and driving conditions, and making it easier to control drift.

[Brief explanation of the drawing]

Fig. 1 is a conceptual diagram of a claim showing a dual-use differential limiting control device of the present invention, Fig. 2 is an overall view of an embodiment of the device of the present invention, and Fig. 3 is a differential limiting control including a hydraulic pressure generating device of an embodiment. FIG. 4 is a concrete block diagram of the differential limiting control circuit of the embodiment device, and FIG. 5 is a flowchart showing the flow of the differential limiting control operation in the embodiment device. ■...Differential limiting clutch means 2...Detection means 201...Accelerator opening detection means 202--One left and right drive rotational speed difference detection means 203...
- Drive wheel slip detection means 3 - clutch control means

Claims (1)

[Claims] 1) A differential limiting clutch means provided between the left and right drive wheels and engaged by an external control force, and an increase/decrease in the differential limiting torque based on a detection signal from a predetermined detection means. A differential limiting control device for a vehicle, comprising: a clutch control means for controlling the vehicle; The clutch control means has a first component that is the sum of a command value that increases in proportion to the accelerator opening degree and a command value that increases in proportion to the rotational speed difference between the left and right driving wheels, and a command value that increases in proportion to the rotational speed difference between the left and right driving wheels. A differential limiter for a vehicle, characterized in that the second component is a command value that is increased by the second component, and a value obtained by subtracting and correcting the second component from the first component is a final differential limiter torque command value. Control device.