JP2629753B2 - Vehicle differential limiting control device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a differential limiting control device for a vehicle, which is used for a differential device of an automobile and controls a differential limiting torque.

(Prior Art) Conventional differential limiting control devices for vehicles include, for example, JP-A-62-103227 (Japanese Patent Application No. 60-244677) and JP-A-61-244677.
An apparatus described in Japanese Patent Application No. 102320 (Japanese Patent Application No. 59-223486) is known.

The former conventional device is a vehicle differential limiting control device capable of controlling a differential limiting torque. It has progressive characteristics.

The latter conventional device is a vehicle differential limiting control device capable of controlling the differential limiting torque, in order to prevent the inner wheel from sticking when turning, to perform large steering at a predetermined vehicle speed or less, a large accelerator opening, and a road surface μ. Is higher, the differential limiting torque is reduced.

(Problems to be Solved by the Invention) However, in the former conventional device, since the differential limiting torque is generated in proportion to only the difference between the rotational speeds of the left and right drive wheels, the torque is large regardless of the accelerator pedal depression operation. As long as there is no difference between the left and right driving wheel rotation speeds, the differential limiting torque remains small, and the driver steps on the accelerator,
There remains a problem that sporty running such as sliding the drive wheels side by side and power sliding cannot be performed.

Also, in the latter conventional device, the differential limiting torque is generated in proportion to only the accelerator opening, so that the outer wheel rotates faster than the inner wheel during turning, that is, so-called accelerator depressing operation before reverse. In the case of performing, the initial understeer tendency tends to occur due to the generation of high differential limiting torque,
The yaw does not occur in the turning direction and the turnability is poor.Sporty running by power slide or the like cannot be expected.If the accelerator is depressed after the reverse is reached, the sporty Although traveling can be expected, there is a problem that a vehicle spin is likely to be induced when a large difference between the driving wheel and non-driving wheel rotational speeds occurs.

(Means for Solving the Problems) The present invention has been made for the purpose of solving the problems described above, and in order to achieve this object, the present invention has the following solution.

The means for solving the present invention will be described with reference to the conceptual diagram of the claim shown in FIG. 1. The differential limiting clutch means 1 provided between the left and right driving wheels and fastened by an external control force, and a predetermined detecting means 2 And a clutch control means 3 for increasing / decreasing the differential limiting torque based on the detection signal of the vehicle.
Accelerator opening detecting means 201, left and right driving wheel rotational speed difference detecting means 202, and left and right non-driving wheel rotational speed difference detecting means 203
And driving wheel-non-driving wheel rotational speed difference detection means 204,
When the sign of the difference between the left and right driving wheel rotation speeds and the difference between the left and right non-driving wheel rotation speeds match, the clutch control means 3 is proportional to the left and right driving wheel rotation speed difference, and the proportional constant is A differential limiting torque command value that is inversely proportional to the opening is output. If the sign of the difference between the left and right driving wheel rotation speeds and the difference between the left and right non-driving wheel rotation speeds does not match, the difference is proportional to the accelerator opening and The proportional constant is a means for outputting a differential limiting torque command value that is inversely proportional to the difference between the driving wheel and non-driving wheel rotational speeds.

(Operation) The power slide travel is a travel in which the driver steps on the accelerator to make a turn using the side slip of the drive wheel. During the turn, the outer wheel rotates faster than the inner wheel. The running condition is different after the reverse where the inner wheel rotates faster than the driving outer wheel.

For this reason, a change in the running condition is determined based on whether the signs of the left and right driving wheel rotation speed difference and the left and right non-driving wheel rotation speed difference match or not. The proportional constant outputs a differential limiting torque command value that is inversely proportional to the accelerator opening, and after reverse, the clutch controlling means 3 is proportional to the accelerator opening and the proportional constant is equal to the drive wheel minus. Control is performed to output a differential limiting torque command value that is inversely proportional to the non-drive wheel rotation speed difference.

Therefore, when the driver enters the corner with the accelerator off and reaches the clipping point and the driver turns on the accelerator, first, in the area before the reverse, a differential limiting torque that decreases as the accelerator opening increases is obtained, and the vehicle tends to understeer. , And a smooth yaw that increases the turning performance in the turning direction is generated. Next, when the vehicle reaches reverse, a differential limiting torque is obtained using the accelerator opening as the vehicle body, and when the difference between the driving wheel and non-driving wheel rotational speeds is small, the gain of the differential limiting for the accelerator opening is high, and the driver has When the power slide easily enters the power slide and the difference between the driving wheel and the non-driving wheel rotation speeds is large, the differential limiting gain is low, and control is performed in a safe direction in which spin is suppressed against spin induction.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings. In describing this embodiment, an example of a differential limiting control device for a rear wheel drive vehicle equipped with a multi-plate friction clutch means operated by an external hydraulic pressure will be described.

 First, the configuration of the embodiment will be described.

As shown in FIG. 2, a rear wheel drive vehicle to which the differential limiting control device D of the embodiment is applied includes a left front wheel 10, a right front wheel 11, an engine 12, a transmission 13, a propeller shaft 14, a differential device 15, A drive shaft 16 on the left wheel side, a drive shaft 17 on the right wheel side, a rear left wheel 18 and a rear right wheel 19 are provided, and the differential device 15 includes a drive input side propeller shaft 14 and a drive output side drive shaft 16. , 17 between the left and right wheels 18, 19
Is provided with a wet multi-plate friction clutch (differential limiting clutch means) 20 for limiting the differential of the clutch.

The wet multi-plate clutch 20 is engaged by a control oil pressure P from a hydraulic pressure generator 30 which is an external device.

As shown in FIG. 3, the differential limiting control device D of the embodiment includes, as input sensors 40, a front left wheel rotation speed sensor 41, a front right wheel rotation speed sensor 42, a rear left wheel rotation speed sensor 43, and a rear right wheel rotation speed. A speed sensor 44, 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 is provided as a control actuator.
There are 60 provided.

The left front wheel rotation speed sensor 41 and the right front wheel rotation speed sensor 42 are means for detecting the rotation speeds of the left and right front wheels 10, 11 which are non-driving wheels, and the left front wheel rotation according to the left front wheel rotation speed NFL is detected from the sensor 41. The speed signal (nf1) and the sensor 42 output a right front wheel rotation speed signal (nfr) corresponding to the right front wheel rotation speed NFR.

The left rear wheel rotation speed sensor 43 and the right rear wheel rotation speed sensor 44 are means for detecting the rotation speed of the left and right rear wheels 18, 19, which are drive wheels, and correspond to the left rear wheel rotation speed NRL from the sensor 43. The left rear wheel rotation speed signal (nf1) and the sensor 44 output a right rear wheel rotation speed signal (nrr) corresponding to the right rear wheel rotation speed NRR.

The accelerator opening sensor 45 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 in-vehicle microcomputer, and has an input interface circuit.
51, a memory 52, a CPL (Central Processing Unit) 53, and an output interface circuit 54.

Incidentally, a specific block diagram of the differential limiting control circuit 50 is as shown in FIG. 4, in which the subtracters 501, 502, 503 and the adder 5
04, 505, EOR gate 506 that checks the sign of the two inputs and outputs “0” when both have the same sign and outputs “1” when they have different signs, 1/2 divider 507, and function generator 508,509, EOR
A switch 510 that receives the output of the gate 506 and switches.

The electromagnetic proportional pressure-reducing valve 60 is provided in the hydraulic pressure generating device 30, and supplies hydraulic pressure of pump pressure supplied from a hydraulic pump 31 via a pump pressure oil passage 32 to a control current signal from a differential limiting control circuit 50. According to (i), the valve actuator controls the pressure of the control oil pressure P proportional to the magnitude of the command current value i *.

Note that the control oil pressure P and the differential limiting torque T have a relationship of T∝P · μ · n · r · En: number of clutches r: average clutch radius E: pressure receiving area, and the differential limiting torque T is controlled. It is proportional to the oil pressure P.

 Next, the operation of the embodiment will be described.

First, the operation 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, the left front wheel rotation speed NFL, the right front wheel rotation speed NFR, and the left front wheel rotation speed NFL are determined based on signals from the sensors 41, 42, 43, 44, and 45.
The left rear wheel rotation speed NRL, the right rear wheel rotation speed NRR, and the accelerator opening A are read.

In step 101, the left and right non-driving wheel rotation speed difference ΔNFrl is calculated by the left front wheel rotation speed NFL and the right front wheel rotation speed NFR read in step 100.

 The arithmetic expression is ΔNFrl = NFL−NFR.

In step 102, the left and right driving wheel rotation speed difference ΔNRrl is calculated from the left rear wheel rotation speed ΔNRL and the right rear wheel rotation speed ΔNRR read in step 100.

 The arithmetic expression is ΔNRrl = NRL−NRR.

In step 103, the front-rear wheel rotation speed difference ΔNfr indicating the drive wheel slip is obtained from the left front wheel rotation speed NFL, the right front wheel rotation speed NFR, the left rear wheel rotation speed NRL, and the right rear wheel rotation speed NRR read in step 100. Is obtained by calculation.

 The arithmetic expression is as follows.

ΔNfr = 1/2 (NRL + NRR) −1/2 (NFL + NFR) In step 104, steps 101 and 102 are performed.
It is determined whether the calculated value of the left and right non-driving wheel rotation speed difference ΔNFrl and the left / right driving wheel rotation speed difference ΔNRrl obtained in the above is the same sign or different sign.

In the case of the same sign, the process proceeds to step 105, and the differential limiting torque T is calculated by an arithmetic expression in which the proportional constant is proportional to the right and left driving wheel rotational speed difference ΔNRrl obtained in step 102 and the proportional constant is inversely proportional to the accelerator opening A. ₁ is required.

The arithmetic expression is T ₁ = K ₁ (A) · ΔNRrl (where K _1
1 (A) is a constant inversely proportional to the accelerator opening A).

As shown in the characteristic diagram of the function generator 508 in FIG. 4, the differential limiting torque T ₁ is linearly proportional to the increase in the right and left driving wheel rotational speed difference ΔNRrl, and the accelerator opening A
Is obtained as a value that decreases with an increase in.

In the case of a different sign, the process proceeds to step 106, and
Proportional to accelerator opening degree A read in 00, the differential limiting torque T ₂ is determined by the calculation equation the proportionality constant is inversely proportional to the front and rear wheel rotational speed difference DerutaNfr.

Note that the arithmetic expression is T ₂ = K ₂ (ΔNfr) · A (where K ₂ (ΔN
fr) is a constant that is inversely proportional to the front and rear wheel rotational speed difference ΔNfr).

As shown in the characteristic diagram of the function generator 509 in FIG. 4, the differential limiting torque T ₂ is linearly proportional to the increase in the accelerator opening A and is inversely proportional to the front and rear wheel rotational speed difference ΔNfr. Is obtained.

In Step 107, Step 105 or Step 10
Differential limiting torque T determined at ₆₁ or differential limiting torque T
A signal (i) based on the command current value i * from which ₂ is obtained is output.

Next, the operation at the time of turning traveling will be described separately for the case of steady turning with a large turning radius and the case of power sliding traveling.

(A) Steady turning with a large turning radius During steady turning with a large turning radius, the lateral acceleration is almost constant, there is no inner wheel slip due to the lifting of the inner wheel, and the rotation of the outer wheel is caused by the turning radius difference irrespective of the driven wheel or non-driven wheel. The state where the speed is higher than the rotation speed of the inner ring is maintained.

For this reason, in the entire turning area from the corner entry to the corner exit, the control operation flow proceeds to step 104 → step 105 → step 107, and is proportional to the left and right drive wheel rotational speed difference ΔNRrl, and the proportional constant is equal to the accelerator opening A. so that the differential limiting torque T ₁ which is inversely proportional to obtain.

Therefore, the lack of generation of a large left driving wheel rotation speed difference DerutaNRrl, differential limiting torque T ₁ is small, the understeer tendency can be suppressed, the increase in the accelerator opening motion A is due to the rise of the left and right drive wheel rotation speed difference DerutaNRrl to a torque correction in a stable direction to suppress the gain of the differential limiting torque T _1, less likely to induce a spin in all road conditions and operating conditions, and the like.

(B) Power slide travel Power slide travel is a travel in which the driver steps on the accelerator to make a turn using the side slip of the drive wheels 18 and 19, and during the turn, the outer wheel rotates faster than the inner wheel. The running conditions are different before and after the reverse, and after the reverse where the drive inner wheel rotates faster than the drive outer wheel.

For this reason, a change in the driving situation is determined in step 104, and before the reverse, step 104 → step 105 → step 10
It becomes the flow of control operations proceed to 7, in proportion to the right and left driving wheel rotation speed difference DerutaNRrl, the proportionality constant operation restricting torque T ₁ which is inversely proportional to the accelerator opening A is obtained, after the reverse,
Step 104 → becomes flow of control operation proceeds to step 106 → Step 107, in proportion to the accelerator opening A, the proportionality constant is that the operation restricting torque T ₂ that is inversely proportional to the front and rear wheel rotational speed difference ΔNfr obtained.

Therefore, enters the corner turn off the accelerator, when the driver reaches the clipping point turns on the accelerator, the first reverse pre-region, the differential limiting torque T ₁ becomes smaller with increasing accelerator opening degree A is obtained This reduces the tendency of understeer and increases the turning ability in the turning direction, thereby producing a smooth yaw. Then, when it comes to reverse,
Differential limiting torque T ₂ obtained the accelerator opening degree A as a main, moreover, when the small front and rear wheel rotation speed difference ΔNfr is
The gain of the differential limit for the accelerator opening A is high, making it easier for the driver to enter the power slide smoothly.
When the front and rear wheel rotation speed difference ΔNfr becomes large, the differential limiting gain is low, and the control is performed in a safe direction in which spin is suppressed with respect to spin induction.

The embodiments of the present invention have been described in detail with reference to the drawings.
The specific configuration is not limited to this embodiment, and the present invention includes any design change or the like without departing from the scope of the present invention.

For example, in the embodiment, an electromagnetic proportional pressure reducing valve is shown as an actuator, but an open / close electromagnetic valve or the like is used.
An example in which hydraulic pressure control is performed using a control signal as a duty signal may be adopted.

Further, in the embodiment, the example in which the differential limiting torque is obtained by the wet multi-plate friction clutch has been described. However, the example may be such that the differential limiting torque is obtained by another clutch such as an electromagnetic clutch or a brake.

(Effects of the Invention) As described above, in the vehicle differential limiting control device of the present invention, the clutch control means sets the sign of the difference between the left and right drive wheel rotation speed difference and the left and right non-drive wheel rotation speed difference. If they match, it is proportional to the difference between the left and right drive wheel rotation speeds, and
The proportionality constant outputs a differential limiting torque command value that is inversely proportional to the accelerator opening, and if the sign of the left and right non-driving wheel rotational speed difference and the sign of the left and right non-driving wheel rotational speed difference do not match, the proportional constant is proportional to the accelerator opening. In addition, the proportional constant is a means for outputting a differential limiting torque command value that is inversely proportional to the driving wheel-non-driving wheel rotational speed difference. It is determined that the vehicle is reverse before and after the vehicle is turned, based on this determination, the initial understeer is reduced before the reverse and at the time of the reverse, the sporty running can be performed while suppressing the vehicle spin. The effect is obtained.

[Brief description of the drawings]

FIG. 1 is a conceptual view of a claim showing a vehicle differential limiting control device according to the present invention, FIG. 2 is an overall view of an embodiment of the present invention, and FIG. 3 is differential limiting control including a hydraulic pressure generating device of the embodiment. FIG. 4 is a specific block diagram of a differential limiting control circuit of the apparatus of the embodiment, and FIG. 5 is a flowchart showing a flow of differential limiting control operation in the apparatus of the embodiment. DESCRIPTION OF SYMBOLS 1 ... Differential limiting clutch means 2 ... Detecting means 201 ... Accelerator opening degree detecting means 202 ... Left and right driving wheel rotational speed difference detecting means 203 ... Left and right driving wheel rotational speed difference detecting means 204 ... Driving wheel-non Driving wheel rotational speed difference detecting means 3 Clutch controlling means

Claims (1)

(57) [Claims] 1. A differential limiting clutch provided between left and right driving wheels and engaged by an external control force, and a differential limiting torque increase / decrease control based on a detection signal from a predetermined detecting means. A vehicle differential limiting control device comprising: a clutch control unit; wherein the detection unit includes an accelerator opening detection unit, a left and right drive wheel rotation speed difference detection unit, a left and right non-drive wheel rotation speed difference detection unit, and a drive wheel. -Non-drive wheel rotation speed difference detection means, wherein the clutch control means, if the sign of the left and right drive wheel rotation speed difference and the sign of the left and right non-drive wheel rotation speed difference,
Outputs a differential limiting torque command value proportional to the difference between the left and right driving wheel rotation speeds and the proportional constant is inversely proportional to the accelerator opening, and the sign of the difference between the left and right driving wheel rotation speed difference and the left and right non-drive wheel rotation speed difference. If does not match, it is proportional to the accelerator opening,
And a means for outputting a differential limiting torque command value whose proportional constant is inversely proportional to the driving wheel-non-driving wheel rotational speed difference.