JPH01101237A - Device for controlling differential limit of vehicle - Google Patents

Abstract

PURPOSE:To prevent spin so as to facilitate drift control by making correction in subtracting No.2 component from No.1 component for determining a differential limit control command value. CONSTITUTION:A differential limit clutching means 1 is engaged by control force from outside. A clutch control means 3 controls differential limit torque to be increased/decreased based on signals from a detecting means 2 consisting of an accelerator opening detecting means 201, a right/left driving wheel rotation speed difference detecting means 202, a driving wheel slip detecting means 203 and of a lateral acceleration detecting means 204. And a clutch control means 3 lets the sum of a command value increasing in proportion to the opening of an accelerator and a command value increasing in proportion to the difference between right and left driving wheel rotation speeds be No.1 component, and lets a command value increasing in proportion to driving wheel slip but in reverse proportion to lateral acceleration be No.2 component so that the correction is made in subtracting No.2 component from No.1 component for determining a differential limit command value.

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 (Patent Application No. 223/1989).
486) 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 differential limiting control device for a vehicle that can control differential limiting torque, and uses large steering, large accelerator opening, and road surface p When is high, the differential limiting torque is reduced.

(Problem to be solved by the invention) However, in the former conventional device, differential limiting torque is generated in proportion to the rotational speed difference between the left and right driving wheels, and in the latter conventional device, the accelerator Since the differential limiting torque is generated in proportion to the opening degree, even if the vehicle yaw rate is excessive during turning acceleration, it is possible to reduce the torque by using the left and right drive wheel rotational speed difference and the accelerator opening as the only control parameters. The differential limiting torque is applied, and as a result,
There was a problem that spin was 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 side limit control device for a vehicle is provided with a clutch control means 3 that performs increase/decrease control of the differential limit torque based on a detection signal of the accelerator opening detection means 201 and a left/right drive The clutch control means 3 includes a wheel rotation speed difference detection means 202, a drive wheel slip detection means 203, and a lateral acceleration detection means 204, and the clutch control means 3 has a command value that increases in proportion to the accelerator opening and a command value that increases in proportion to the left and right drive wheel rotation speed difference. The sum of the command value and the increasing command value is the first
and a second component is a command value that increases in proportion to drive wheel slip and inversely proportional to lateral acceleration;
The differential limiting control command value is determined by subtracting and correcting the second component from one component.

(Function) During steady turning with a large turning radius, the lateral acceleration is almost constant;
Since the accelerator opening degree is low and there is little slippage of the drive wheels, 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 the 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 limit torque is increased. By lowering the 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 inner 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, which is proportional to drive wheel slip and inversely proportional to lateral acceleration, from the command value mainly based on the accelerator opening, making drift control easier. .

That is, basically, as drive wheel slip increases, drift control becomes more difficult, so the solution is to reduce differential limiting torque in proportion to drive wheel slip. However, it is necessary to allow a certain amount of drive wheel slip when making a small radius turn on a high end road with large lateral acceleration, and eliminate the effect of drive wheel slip when making a large turning radius turn on a low end road where lateral acceleration is small. 8. The command value to be subtracted from the command value mainly based on the accelerator opening is set to be a value inversely proportional to the lateral acceleration.

(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.

The rear wheel drive vehicle to which the differential limiting control device of the embodiment is applied has a left front wheel 10, a right Fiif wheel 11, as shown in FIG.
, engine 12, transmission 13, propeller shaft 14, differential gear 15. Left wheel drive shaft 1
6. It is equipped with a right wheel side drive shaft 17, a left rear wheel 18, and a right rear wheel 19, and the differential device 15 has a propeller shaft 14 on the drive input side and a drive shaft 16, 17 on the drive output side. In between, there is a wet multi-disc friction clutch (differential limiting clutch means) 2 that limits the differential movement between the left and right wheels 18 and 19.
0 is set.

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 41 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.
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 mainly based 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.
, averaging units 504 and 505, and lateral acceleration calculator 5.
06, function generators 507, 508, and 509, and an adder/subtractor 510.

The electromagnetic proportional pressure reducing valve 60 is connected to the hydraulic pressure generator 30.
The hydraulic oil at the pump pressure supplied from the hydraulic pump 31 via the pump pressure oil path 32 is controlled by the control current signal (i) from the differential limiting control circuit 50 to the magnitude of one command current value. This is a pulp actuator that controls pressure to a control oil pressure P proportional to .

The control oil pressure P and the differential limiting torque T have the following relationship: ToCP-ru-n-r-E n; number of clutches r: clutch average radius E; pressure receiving area; the differential limiting torque T is the control oil pressure P. is proportional to.

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 lateral acceleration Yg is calculated using the front left wheel rotation speed NFL and the front right wheel rotation speed NFR read in step 100.

The calculation formula is as follows, assuming turning radius R, vehicle speed V, and yaw rate φ.

V= ((NFL+NFR)/2) /rψ=Kl
-l NFL-NFRI R=V/ψ = 2・l (NFL+NFR) / (NFL-N
FR) IYg=■2 /R=に3・I (NFL+NFR) Book (NFL-NFR)
1 However, Kl, 2. 3 is a proportionality constant determined by the vehicle specifications, and r is the tire radius.

In step 102, a left and right drive wheel rotational speed difference ΔNr statement 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 l =NRL - NRR.

In step 103, front and rear wheel rotation speeds indicating drive wheel slip and lip are determined 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 difference ΔNfr is calculated.

Note that the calculation formula is as shown below.

ΔN f r = 'It (NRL+NRR) −
372 (NFL+NFR) At step 104, the left and right drive wheel rotational speed difference ΔNr obtained at step 102 is calculated.
A differential limiting torque T1 proportional to l is determined.

Note that this differential limiting torque T1 is calculated by the function generator 5 in FIG.
As shown in the characteristic diagram of No. 07, it is obtained as a value that is linearly proportional to the increase in the rotational speed difference ΔNrl between the left and right driving wheels.

In step 105, 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. 08, it is obtained as a value that is linearly proportional to the increase in accelerator opening A.

In step 106, differential limiting torque T3 is determined which is proportional to the front and rear wheel rotational speed difference ΔNfr obtained in step 103 and whose proportionality constant (gain) is inversely proportional to the lateral acceleration Yg obtained in step 101.゛This differential limiting torque T3 is calculated by the function generator 5 in FIG.
As shown in the characteristic diagram of 09, the front and rear wheel rotational speed difference Δ
It is linearly proportional to the increase in Nfr, and is obtained as a larger value as the lateral acceleration Yg is smaller, and as a smaller value as the lateral acceleration Yg is smaller. In step 107, from the differential limiting torques T1, T2, and T3, The final differential limiting torque T is calculated.

Note that the calculation formula for the final differential limiting torque T is as shown in the first order.

T=71 +72-Ts At step 108, a signal (i) based on a command current value of 1 quintillion at which the final differential limiting torque T is obtained 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 lateral acceleration Yg is almost constant, the accelerator opening A is low, and the front and rear wheel rotational speed difference ΔNfr due to drive wheel slip is small, so left-right drive The influence of the wheel rotational speed difference ΔNrl is greatest. Therefore, the final differential braking daughter torque T is determined based on the differential limiting torque T1 based on the left and right driving wheel rotational speed difference ΔNr statement.

The differential limiting torque T2 is proportional to the accelerator opening A.
In addition, 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 ΔNrl, so that it can be applied to 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 (T10T2) to suppress an increase in the left and right drive wheel rotational speed difference ΔNrl.

Furthermore, 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 (Tz - Tz) to suppress an increase in the left and right drive wheel rotational speed difference ΔNrJl.

(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 rotational speed difference between the left and right drive wheels ΔNr
l is small, differential limiting torque T2 due to accelerator opening A
The final differential limiting torque T is determined mainly based on.

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 rotation speed difference ΔNfr and inversely proportional to the lateral acceleration Yg, from the differential limiting torque T2, which is proportional to the accelerator opening degree A. This makes drift control easier.

That is, basically, as the drive wheel slip increases, drift control becomes more difficult, so this is dealt with by reducing the differential limiting torque T in proportion to the drive wheel slip.

However, when making a small radius turn on a high p road where the lateral acceleration Yg is large, a certain amount of drive wheel slip should be allowed, and when making a large turning radius turn on a low Hiro road where the lateral acceleration Yg is small, the influence of drive wheel slip may be allowed. Therefore, the differential limiting torque T3, which is subtracted from the differential limiting torque T2 which is proportional to the accelerator opening A, is set to a value inversely proportional to the lateral acceleration Yg.

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 the actuator, but an example in which an electromagnetic valve that opens and closes or the like may be used to perform hydraulic control using a control signal as a duty signal may also be used.

Talented. In the embodiment, an example is shown in which differential limiting torque is obtained using a wet multi-disc friction clutch, but an example in which differential limiting torque is obtained using other clutches such as an electromagnetic clutch, a brake, etc. may be used.

Further, in the embodiment, an example has been shown in which the lateral acceleration is determined by calculation, but it may also be determined by calculation from the steering angle or vehicle speed, or a lateral acceleration sensor may be used.

Furthermore, although an example is shown in which the difference in rotational speed between the front and rear wheels is used as drive wheel slip information, 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 drive wheel slip, and the second component is the command value that increases in proportion to the drive wheel slip and inversely proportional to the lateral acceleration. Since the method is characterized in that the differential limiting control command value is determined by subtracting and correcting the second component, it is difficult to induce spin under all road surface conditions and driving conditions, and drift control is facilitated. The effect is that it can be done.

[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. l...Differential limiting clutch means 2...Detection means 201...Accelerator opening detection means 202...Left and right drive wheel rotational speed difference detection means 203...
- Drive wheel slip detection means 204... Lateral acceleration 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; and the detection means includes an accelerator opening detection means, a left and right drive wheel rotational speed difference detection means, a drive wheel slip detection means, and a lateral acceleration detection means. The clutch control means has a first component that is a 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 drive wheels, and A second component is a command value that increases in proportion to slip and inversely proportional to lateral acceleration, and the differential limiting control command value is determined by subtracting and correcting the second component from the first component. A limited differential control device for vehicles.