JPH01153341A - Vehicle differential motion limiting device - Google Patents

Abstract

PURPOSE:To make it possible to sportily run a vehicle by determining whether the vehicle is before or after reverse operation in accordance with whether the sign of a difference in rotational speed between right and left drive wheels coincides with the sign of a difference in rotational speed between right and left driven wheels or not, so as to deliver a torque instruction value for limiting differential motion. CONSTITUTION:A clutch control means 3 determines whether the sign of a difference in rotational speed between right and left drive wheels coincides with the sign of a difference in rotational speed between right and left driven wheels or not, and if they coincide with each other, the clutch control means 3 delivers a torque instruction value for limiting differential motion, which is proportional to the difference in rotational speed between the right and left drive wheel at a ratio inversely proportional to an accelerator opening degree, to a differential motion limiting clutch means 1. Meanwhile if they do not coincide with each other, it delivers a torque instruction value for limiting differential motion which is proportional to an accelerator opening degree at a ratio inversely proportional to the difference in rotational speed between the right and left driven wheels. Thus, it is determined whether the drive mode is before or after reverse operation, and accordingly, the initial understeering is reduced if it is before the reverse operation, and it is possible to sportily run the vehicle while restraining vehicle spin when the reverse operation is effected.

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 former conventional device, the differential limiting torque is generated in proportion only to the rotational speed difference between the left and right driving wheels, so a large amount of torque is generated regardless of the accelerator pedal operation. As long as there is no rotational speed difference between the left and right drive wheels, the differential limiting torque remains small, leaving the problem that the driver cannot perform sporty driving where the driver depresses the accelerator and causes the drive wheels to skid sideways and perform a power slide. .

In addition, since the latter conventional device was configured to generate differential limiting torque in proportion to only the accelerator opening, the outer wheel rotates faster than the inner wheel during a turn, so it is difficult to press the accelerator before reversing. If this is done, a high differential limiting torque will be generated, resulting in an initial understeer tendency.
There is no yaw in the turning direction, resulting in poor turning performance, and you cannot expect a sporty driving experience with power slides, etc., and if you press the accelerator after reaching reverse, a high differential limiting torque will be generated, resulting in a sporty driving experience. However, if there is a large difference in rotational speed between the driving wheels and the non-driving wheels, the problem remains that the vehicle is likely to spin.

(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 claims 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 The clutch control means 3 includes a rotational speed difference detection means 202, a left and right non-driving wheel rotational speed difference detection means 203, and a driving wheel-non-driving wheel rotational speed difference detection means 204. If the sign matches the difference in rotational speed of the driving wheels, outputs a differential limiting torque command value that is proportional to the difference in rotational speed of the left and right driving wheels, and whose proportionality constant is inversely proportional to the accelerator opening; If the signs of the rotational speed difference between the left and right driving wheels and the rotational speed difference between the left and right non-driving wheels do not match.

It is proportional to the accelerator opening degree, and its proportional constant is -
The present invention is characterized by means for outputting a differential limiting torque command value that is inversely proportional to the difference in rotational speed of the non-driven wheels.

(Function) Power slide driving is a driving operation in which the driver depresses the accelerator and uses the skidding of the drive wheels to turn. During the turn, the outer wheels rotate faster than the inner wheels, so-called before reversing The driving situation is different after reverse, where the inner wheels rotate faster than the driving outer wheels.

For this reason, changes in driving conditions are determined by the coincidence or mismatch of signs between the left and right driving wheel rotational speed difference and the left and right non-driving wheel rotational speed difference.
Before reversing, the clutch control means 3 outputs a differential limiting torque command value which is proportional to the rotational speed difference between the left and right driving wheels and whose proportionality constant is inversely proportional to the accelerator opening. is proportional to the accelerator opening degree, and.

The proportional constant is controlled to output a differential limiting torque command value that is inversely proportional to the rotational speed difference between the driving wheels and the non-driving wheels.

Therefore, when the driver enters a corner with the accelerator off, reaches the clipping point, and then turns on the accelerator, in the region before reverse, differential limiting torque is obtained that decreases as the accelerator opening increases, and there is a tendency for understeer. A smooth yaw is generated that reduces the rotational speed and increases turning performance in the turning direction. Next, when reverse is reached, the differential limiting torque is obtained mainly based on the accelerator opening, and moreover,
When the rotational speed difference between the driving wheels and the non-driving wheels is small, the differential limiting gain relative to the accelerator opening is high, making it easier for the driver to smoothly enter the power slide. The limiting gain is low, and control is performed in a safe direction to suppress spin against spin induction.

(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, a rear wheel drive vehicle to which the differential limiting control device of the embodiment is applied includes a left front wheel 1O1, a right front wheel 11, an engine 12, a transmission 13, a propeller shaft 14, a differential device 15, and a left wheel. Side drive shaft 16, right wheel side drive shirt 1-17, left rear wheel 18, right rear wheel 19
The differential device 15 includes a propeller shaft 14 on the drive input side and a drive shaft 1 on the drive output side.
6.17, a wet multi-disc friction clutch (differential limiting clutch means) 20 is provided to limit the differential movement between the left and right wheels 18,19.

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, a differential limiting control circuit 50 is provided as a control module, 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 41 detects the left curved axis rotation 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.
A left rear wheel rotational speed signal (nrl) corresponding to RL and a right rear wheel rotational speed signal (nrr) corresponding to the right rear wheel rotational speed NRR are output from the sensor 44.

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 limiting control circuit 50 is shown in FIG.
, adders 504 and 505, an EOR gate 506 that checks the signs of the two inputs and outputs "O" when they are the same sign and outputs -1'' when they are different signs, and a divider 5.
07, function generation 1508.509, and EOR gate 5
06.

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.

In addition, the control oil pressure P and the differential limiting torque T are TCcP-μ
・nr-E n: Number of clutches r: Clutch average radius E: Pressure-receiving area, and the differential limiting torque T is proportional to the 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 lOO, 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 lot, the left and right non-drive wheel rotational speed difference ΔNFr[ is calculated from the left front wheel rotational speed NFL and the right front wheel rotational speed NFR read in step 100.

Note that the calculation formula is ΔNFrg=NFL−NFR.

In step 102, the left and right drive wheel rotational speed difference ΔNRrI2 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 ΔNRrn=NRL−NRR.

In step 103, 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 100, 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)-y2(NF
L+NFR) In step 104, the step 101
Then, it is determined whether the calculated values of the left and right non-driven wheel rotational speed difference ΔNFrβ and the left and right driven wheel rotational speed difference ΔNRrg obtained in step 102 have the same sign or different signs.

If the signs are the same, proceed to step 105, and step 10
The differential limiting torque T is determined by an arithmetic expression that is proportional to the left and right drive wheel rotational speed difference ΔNRrJ2 obtained in step 2, and whose proportionality constant is inversely proportional to the magnitude of the accelerator opening A.

The calculation formula is T, = (A)-8Nflrj2 (where K and (A) are constants inversely proportional to the accelerator opening A).

As shown in the characteristic diagram of the function generator 508 in FIG. It is obtained as a decreasing value.

If the signs are different, the process proceeds to step 106, where the differential limiting torque T2 is determined using an arithmetic expression that is proportional to the accelerator opening degree A read in step 100 and whose proportionality constant is inversely proportional to the front and rear wheel rotational speed difference ΔNfr. .

The calculation formula is T 2'' K 2 (ΔNfr)-A(
However, K2 (ΔNfr) is the difference in rotational speed between the front and rear wheels ΔNfr
(a constant inversely proportional to ).

As shown in the characteristic diagram of the function generator 509 in FIG.
It is obtained as a value that is linearly proportional to the increase in ΔNfr and inversely proportional to the front and rear wheel rotational speed difference ΔNfr.

In step 107, a signal (i
) is output.

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

(a) Steady turning with a large turning radius During a steady turning with a large turning radius, the lateral acceleration is almost constant;
There is no slippage of the inner wheel due to lifting of the inner wheel, and the rotational speed of the outer wheel is maintained higher than the rotational speed of the inner wheel due to the difference in turning radius, regardless of whether the wheel is driven or not.

For this reason, the control operation flow proceeds from step 104 to step 105 to step 107 in the entire turning region from corner entry to corner exit, and the rotational speed difference ΔNR of the left and right driving wheels is
A differential limiting torque T1 is obtained which is proportional to rβ and whose proportionality constant is inversely proportional to the accelerator opening A.

Therefore, since there is no occurrence of a large left and right drive wheel rotational speed difference ΔNRrI2, the differential limiting torque T is small and the understeer tendency is suppressed. Since the torque is corrected in a stable direction that suppresses the gain of the differential limiting torque T1 due to the increase, spins are less likely to be induced under all road conditions and driving conditions.

(b) Power slide driving Power slide driving is a driving in which the driver depresses the accelerator and makes a turn using the skidding of the drive wheels18, 19. During the turn, the outer wheel rotates faster than the inner wheel. The driving situation is different before so-called reverse and after reverse, where the driving inner wheel rotates faster than the driving outer wheel.

For this reason, changes in the driving situation are determined in step 104, and before reversing, the flow of control operation proceeds from step 104 to step 105 to step 107, which is proportional to the left and right drive wheel rotational speed difference ΔNRr12, and its proportional constant is the accelerator. A differential limiting torque T1 is obtained which is inversely proportional to the opening degree A, and after reversing, the flow of control operation proceeds from step 104 → step 106 → step 107, which is proportional to the accelerator opening degree A, and its proportional constant is the rotation of the front and rear wheels. Speed difference ΔNfr
A differential limiting torque T2 that is inversely proportional to is obtained.

Therefore, when the driver enters a corner with the accelerator off, reaches the clipping point, and turns on the accelerator, first, in the region before reverse, differential limiting torque T1 is obtained, which decreases as the accelerator opening degree A increases, A smooth yaw is generated that reduces understeer tendency and increases turning performance. Then, when it comes to reverse,
When the differential limiting torque T2 is obtained mainly from the accelerator opening A, and the difference in rotational speed between the front and rear wheels ΔNfr is small, the gain of the differential limiting with respect to the accelerator opening A is high (and the driver can smoothly enter the power slide. When the rotational speed difference ΔNfr between the front and rear wheels becomes large, the differential limiting gain becomes low, and control is performed in a safe direction to suppress spins against induced spins.

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, and the present invention may be modified without departing from the gist of the present invention. included.

For example, in the embodiment, an electromagnetic proportional pressure reducing valve is shown as an actuator, but an example in which an electromagnetic pulp or the like for opening and closing 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.

(Effects of the Invention) As explained above, in the differential limiting control device for a vehicle of the present invention, the clutch control means.

If the signs of the left and right driving wheel rotational speed difference and the left and right non-driving wheel rotational speed difference match, the difference is proportional to the left and right driving wheel rotational speed difference, and the proportionality constant is inversely proportional to the accelerator opening degree. When the dynamic limit torque command value is output and the signs of the rotational speed difference between the left and right driving wheels and the rotational speed difference between the left and right non-driving wheels do not match, it is proportional to the accelerator opening degree, and its proportional constant is Since the means is used to output a differential limiting torque command value that is inversely proportional to the difference in rotational speed of the driving wheels, front and rear reverse is determined based on whether the signs of the difference in rotational speed between left and right driving wheels and the difference in rotational speed between left and right non-driving wheels match or do not match. , Based on this determination, when turning, the initial understeer is reduced before reversing,
Furthermore, when the vehicle is in reverse, it is possible to achieve sporty driving while suppressing vehicle spin.

[Brief explanation of the drawing]

Fig. 1 is a conceptual diagram of a claim showing a differential limiting control device for a vehicle 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 detailed 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...-Left and right drive wheel rotational speed difference detection means 203...
- Left and right drive wheel rotational speed difference detection means 204... drive wheel -
Non-driven wheel rotational speed difference 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 performing control, wherein the detection means includes an accelerator opening degree detection means, a left and right driven wheel rotation speed difference detection means, and a left and right non-drive wheel rotation speed difference detection means. and driving wheel-non-driving wheel rotational speed difference detection means, and the clutch control means detects when the signs of the left-right driving wheel rotational speed difference and the left-right non-driving wheel rotational speed difference match,
Outputs a differential limiting torque command value that is proportional to the rotational speed difference between the left and right driven wheels, and whose proportionality constant is inversely proportional to the accelerator opening, and determines the sign of the rotational speed difference between the left and right driven wheels and the rotational speed difference between the left and right non-driven wheels. If they do not match, it will be proportional to the accelerator opening,
A differential limiting control device for a vehicle, further comprising means for outputting a differential limiting torque command value whose proportionality constant is inversely proportional to the rotational speed difference between the driving wheels and the non-driving wheels.