JP3136766B2 - Vehicle slip control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a slip control device for preventing a slip caused when a driving force applied to driving wheels of a vehicle becomes excessive.

[0002]

2. Description of the Related Art Conventionally, the amount of heat generated between a pinion gear and a pinion shaft, which are components of a differential of a vehicle (hereinafter referred to as "differential"), is different from a rotational speed V generated by a speed difference between left and right drive wheels. It is known that it is proportional to the surface pressure P between the two (the cumulative value of the product of the two is called the PV value). Here, JP-A-64-4436
A vehicle disclosed in Japanese Patent Publication No. 9 "Vehicle slip control device" is known. When the speed difference between the left and right driving wheels is larger than a predetermined value, normal slip control is performed, and when the speed difference is smaller than the predetermined value, the control pattern of the low speed wheel is made dependent on the high speed wheel to converge the speed difference and hunting is performed. We are trying to prevent it. That is, in the slip control device, the slip of the high-speed wheels is suppressed, and the speed fluctuation of the left and right opposite phases caused by the differential action of the differential is prevented.

[0003]

However, after the occurrence of a large speed difference, the control is performed under the condition that the speed difference is reduced by the differential action of the differential, so that the control is carried out while the speed difference is actually occurring (especially There is no effect on the first time when the speed difference occurs). Now, assume that a slip has occurred and a speed difference has occurred between the left and right driving wheels. Then, a braking force is applied to the low-speed wheels. For this reason, the speed difference between the left and right driving wheels is increased rather than when no braking force is applied. That is, in the conventional slip control device, when the speed difference is large, a large amount of heat is generated between the pinion gear and the pinion shaft of the differential, so that the load is applied to the differential, and the differential is not sufficiently operated. there were.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a slip control device for a vehicle, in which a difference in speed between left and right driving wheels is suppressed to protect a differential gear. It is to plan.

[0005]

The first feature of the present invention for solving the above-mentioned problem is that, as shown in FIG. 7, the concept of the invention is to apply the torque generated by the engine to the left and right drive wheels via a differential. A wheel speed detecting means G1 for detecting a wheel speed of each wheel in the vehicle to be transmitted, a reference speed creating means G2 for creating a reference speed for the wheel speed detected by the wheel speed detecting means G1, A driving wheel slip detecting means G3 for detecting a slip state of each of the left and right driving wheels from the wheel speed detected by the wheel speed detecting means G1 and the reference speed generated by the reference speed generating means G2; A slip control amount calculating means G4 for calculating a slip control amount based on the slip state detected by the drive wheel slip detecting means G3; and a slip control amount calculating means G4. And a braking force adjusting means G5 for independently adjusting the braking forces applied to the left and right driving wheels based on the calculated slip control amount. A driving wheel speed difference calculating means G6 for calculating a driving wheel speed difference between the left and right driving wheels from the wheel speed, and correcting the slip control amount based on the driving wheel speed difference calculated by the driving wheel speed difference calculating means G6. And a slip control amount correcting means G7. Here the content of G7 is driven
The driving wheel speed difference calculated by the wheel speed difference calculating means G6 is set.
If it is larger than the fixed value, the slip control amount of the high-speed drive wheel
-Speed wheel slip control amount correction means for performing correction to increase
And the driving wheel speed difference is larger than the set value
Wheel speed reduction is absolutely greater than another setpoint
In other words, make corrections to increase the slip control amount of the low-speed drive wheels.
Low-speed wheel slip control amount correction means.

[0006] The second feature is, in addition to the first feature,
Turning state detecting means for detecting a turning state of the vehicle, and driving for correcting the drive wheel speed difference calculated by the drive wheel speed difference calculating means based on the turning state detected by the turning state detecting means. Wheel speed difference correction means.

[0007]

According to the above-described means, the wheel speed and the wheel acceleration of the left and right driving wheels connected via the differential are detected, and the reference speed as the control target is calculated. A slip state of each wheel is detected by comparing the wheel speed with the reference speed, and a slip control amount is determined so that the detected slip state approaches a desired state. Further, the speed difference is calculated and the slip control amount is corrected, so that the speed difference is prevented from increasing. This content is set by the drive wheel speed difference.
If the value is larger than the value, the slip control amount of the
Drive speed difference is larger than the set value
Side drive wheel speed reduction is greater in absolute value than another set value
If it is, increase the slip control amount of the low-speed drive wheel
Make corrections.

[Operation of the Second Feature] In addition to the operation of the first feature, the turning state of the vehicle is detected, and the driving wheel speed difference is corrected based on the turning state. Therefore, even when a speed difference occurs between the left and right drive wheels due to the turning state, the speed difference is appropriately suppressed.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to specific embodiments. FIG. 1 is a block diagram showing the configuration of a front-wheel drive vehicle provided with a vehicle slip control device according to the present invention. The vehicle is a front left wheel (FL wheel) 3 and a front right wheel (FR
Wheel) 4, a left rear wheel (RL wheel) 5, and a right rear wheel (RR wheel) 6. The output of the engine 2 mounted on the vehicle is the differential 1
Is transmitted to the FL wheel 3 and the FR wheel 4 via the. Each wheel 3
6, speed sensors 9 to 12 for detecting wheel speeds are provided in one-to-one correspondence.

The electronic control unit (ECU) 13
It consists of a well-known microcomputer, CPU, ROM
And a RAM. This ECU 13
Receives signals from the speed sensors 9 to 12, determines the slip state of the FL wheels 3 and the FR wheels 4 as drive wheels, and outputs control signals to the brake devices 7 and 8. That is, the ECU 1
3 inputs the speed signals from the speed sensors 9 to 12 of the wheels 3 to 6, calculates the speed and acceleration of the wheels 3 to 6, and calculates F
The slip state of the L wheel 3 and the FR wheel 4 is determined. Then, the speed difference between the left and right drive wheels is calculated, the turning state of the vehicle is determined from the speed difference between the RL wheels 5 and RR wheels 6 as the rolling wheels, and if the turning state is detected, the calculated drive wheel speed difference is corrected. . For example, if BF * = 0.3, it means that the pressure increase is performed at a rate of 3 and a hold 7 per unit time. Next, a slip control amount (combination based on a rate of increase / decrease in brake oil pressure per unit time) is determined for each of the left and right drive wheels according to the slip state of the drive wheels, and a corresponding control signal is transmitted to each brake device 7. , 8. At this time, if the speed difference of the drive wheels (corrected as required) is equal to or greater than a predetermined value, the correction is performed so that the speed difference becomes smaller with respect to the slip control amount. The brake devices 7 and 8 can apply a braking force to the FL wheel 3 and the FR wheel 4 independently by a control signal from the ECU 13. In addition, a hydraulic system including a known hydraulic pump, accumulator, master cylinder, and the like is connected to the brake devices 7 and 8.

Next, the EC used in the apparatus of this embodiment is
A detailed description will be given based on the flowchart of FIG. 2 showing the procedure of the drive wheel slip control executed by U13 with reference to the maps of FIGS. 3, 4, 5 and the timing chart of FIG. First, in step 100, based on the speed signals input from the speed sensors 9 to 12, the rotation speed of each wheel, that is, the driving wheel speed VFL, F of the FL wheel 3,
The driving wheel speed VFR of the R wheel 4 (see FIG. 6A), the rolling wheel speed VRL of the RL wheel 5, and the rolling wheel speed VRR of the RR wheel 6 are calculated. Next, the routine proceeds to step 102, where the drive wheel accelerations WFL and WFR are calculated from the temporal changes of the drive wheel speed VFL of the FL wheel 3 and the drive wheel speed VFR of the FR wheel 4 (FIG. 6B).
reference). Next, the routine proceeds to step 104, where the vehicle speed VS0 is calculated from the rolling wheel speeds VRL and VRR in order to determine the slip state of the drive wheels, and the reference speed VS1 is calculated based on the vehicle speed VS0 (see FIG. 6A). .

## EQU1 ## VS0 = (VRL + VRR) / 2 VS1 = VS0 + K1 Here, K1 is set according to the type of a vehicle such as a family car or a sports car, and a value such as K1 = 2 km / h is obtained so as to obtain the preferable acceleration. Selected. Next, the routine proceeds to step 106, where the control start speed VS2 is calculated from the reference speed VS1 calculated in step 104 (FIG. 6).
(a)).

VS2 = VS1 + K2 Here, for example, K2 = 3 km / h. Then step 1
08, the driving wheel speed difference VFDEC (see FIG. 6C) from the driving wheel speeds VFL and VFR of the left and right driving wheels, and the rolling wheel speed difference VRDEC from the rolling wheel speeds VRL and VRR of the left and right rolling wheels. Calculate each.

## EQU3 ## VFDEC = VFL-VFR VRDEC = VRL-VRR

Then, the routine proceeds to step 110, where it is determined from the magnitude of the rolling wheel speed difference | VRDEC | calculated at step 108 whether or not the vehicle is turning. Here, |
When the condition of VRDEC |> K3 is satisfied, the process proceeds to step 112 assuming that the vehicle is turning, and when the condition is not satisfied and the vehicle is not in the turning condition, the process proceeds to step 114. Here, for example, K3 = 2 km / h. In step 112, the drive wheel speed difference | VRDEC calculated in step 108
After performing the turning correction for |, the process proceeds to step 114.

## EQU4 ## VFDEC = VFDEC-VRDEC

At step 114, it is determined whether or not the slip control is already being executed. If the slip control is being performed, the process proceeds to step 118, and if not, the process proceeds to step 116. In step 116, it is determined whether or not the drive wheel 3 or the drive wheel 4 has slipped. Here, the drive wheel speed VFL or the drive wheel speed VFR calculated in step 100 is compared with the control start speed VS2 calculated in step 106. VFL> VS2 or VFR
If the condition> VS2 is satisfied, it is determined that a slip has occurred, and the routine proceeds to step 120. On the other hand, if the above condition is not satisfied, it is determined that there is no slip and the process returns to step 100 to repeat the above steps. In step 118,
It is determined whether the slip of the driving wheel 3 or the driving wheel 4 has converged. Here, the speed VF * of the drive wheel under the slip control is compared with the reference speed VS1 calculated in step 104, and if the condition of VF * ≦ VS1 is satisfied, it is determined that the slip has converged, and step 100 is performed. And the above steps are repeated. On the other hand, if the above condition is not satisfied, the process proceeds to step 120 as slip continuation. In step 120, the difference between the speed VF * of the slipping drive wheel and the reference speed VS1 calculated in step 104 is calculated as the slip amount ΔVF *. Note that an asterisk indicates a wheel that is slipping at R or L.

ΔVF * = VF * −VS1 Next, the routine proceeds to step 122, where the slip control amount BF * is calculated from the slip amount ΔVF *. At this time, the slip control amount B is set for the wheel determined not to be slipping.
F * = 0. Here, there is a relationship as shown in FIG. 3 (a) between the slip amount ΔVF * (km / h) and the slip control amount BF *, and K4 and K5 in FIG. Is determined as follows. However, WF * is the drive wheel (F * wheel) where the slip occurred.
Wheel acceleration (G). Also, for example, K6 = −1.5
(G), K7 = 1.5 (G). Note that the slip control amount BF
* Indicates the increasing / decreasing gradient of the brake hydraulic pressure. The positive direction indicates increasing pressure and the negative direction indicates decreasing pressure. For example, if BF * = 0.3, it means that pressure increase is performed at a rate of 3 and a holding 7 per unit time.

Next, the routine proceeds to step 124, where it is determined from the drive wheel speed difference | VFDEC | whether or not to correct the slip control amount. Here, the drive wheel speed difference | VFDEC | is compared with K8, and if | VFDEC |> K8 is satisfied and it is determined that correction is necessary, the routine proceeds to step 126, while | VFDEC |
> K8 is not satisfied and it is determined that the correction is unnecessary, step 1
32. Here, for example, K8 = 7km
/ h. Hereinafter, the high-speed side of the drive wheels (FK
Wheels) and the low-speed side are called low-speed wheels (FT wheels). The wheel speeds are VFK and VFT, the wheel accelerations are WFK and WFT, and the slip control amounts are BFK and BFT. At step 126, the slip control amount BFK of the high-speed wheel is corrected. At this time, there is a relationship as shown in FIG. 4 between the correction amount ΔBFK of the slip control amount BFK of the high-speed wheels and the drive wheel speed difference | VFDEC | (km / h). Here, for example, the upper limit of the correction amount ΔBFK is K
10 = 0.2, the threshold of the drive wheel speed difference | VFDEC |
20 km / h.

BFK = BFK + ΔBFK where the upper limit of the corrected slip control amount BFK is 1.

Then, the program proceeds to a step 128, wherein it is determined whether or not the slip of the high-speed wheel is converging. Here, the wheel acceleration WFK of the high-speed wheel is compared with K9, and W
If it is determined that FK ≦ K9 holds, it is determined that the slip of the high-speed wheel is approaching convergence.
Are satisfied and it is determined that the slip of the high-speed wheel does not converge, the process proceeds to step 132. Where, for example,
K9 = −0.5 (G). In step 130, a correction is made to the slip control amount BFT of the low-speed wheel. At this time, between the correction amount ΔBFT of the slip control amount BFT of the low-speed wheel and the peak value | VPFDEC | (km / h) of the driving wheel speed difference, FIG.
There is such a relationship. Here, for example, the upper limit of the correction amount ΔBFT is K12 = 0.1, and the peak value of the drive wheel speed difference | VPF
The threshold value of DEC | is K13 = 15 km / h.

BFT = BFT + ΔBFT where the upper limit value of the corrected slip control amount BFT is 1. Also, at this time, by determining the correction amount of the low-speed wheel corresponding to the peak value of the drive wheel speed difference, a sudden slip occurs in the low-speed wheel due to the torque transmitted to the low-speed wheel by the differential action of the differential. Can be prevented. Then, the routine proceeds to step 132, where the brake devices 7, 8 corresponding to the respective drive wheels are driven by the slip control amounts BFK, BFT.

As described above, in the vehicle slip control device according to the present invention, the slip control amount based on the drive wheel speed difference is corrected. In other words, the correction amount shown in FIG. 6E is taken into account during the period in which the correction is performed on the high-speed and low-speed wheels shown in FIG. As a result, the left and right driving wheel speeds by the conventional slip control shown by the two-dot chain line in FIG. 6A are suppressed as the left and right driving wheel speeds shown by the solid line, and the speed difference can be reduced. Therefore, the load on the differential can be reduced.

[0017]

【The invention's effect】

"First effect" The present invention is configured as described above, and the slip state is usually controlled by comparing the wheel speed with the reference speed to detect the slip state of each wheel and to determine the slip control amount. At this time, the speed difference between the left and right driving wheels is calculated, and the slip control amount is corrected so as to suppress the speed difference when the speed difference exceeds a predetermined value. As a result, the difference in speed between the left and right drive wheels does not become too large, and a large load is not applied to the differential.

"Second effect" In addition to the effect of the first feature,
Since the turning state of the vehicle is detected and the speed difference is corrected,
Even when there is a speed difference between the left and right driving wheels in the turning state, the speed difference is appropriately controlled.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of a front-wheel drive vehicle equipped with a vehicle slip control device according to a specific embodiment of the present invention.

FIG. 2 is a flowchart showing a processing procedure of an ECU used in the apparatus of the embodiment.

FIG. 3 is a map showing a relationship between a slip amount ΔVF * and a slip control amount BF * according to the embodiment.

FIG. 4 is a map showing a relationship between a drive wheel speed difference | VFDEC | and a correction amount ΔBFK of a slip control amount of a high-speed wheel according to the embodiment.

FIG. 5 is a diagram illustrating a peak value of a drive wheel speed difference | VPF according to the embodiment.
9 is a map showing a relationship between DEC | and a correction amount ΔBFT of a slip control amount of a low-speed wheel.

FIG. 6 is a timing chart showing slip control in the vehicle slip control device according to the present invention.

FIG. 7 is a block diagram illustrating the concept of the present invention.

[Explanation of symbols]

 1-Diff (differential: differential) 2-engine 3-FL wheel (left front wheel) 4-FR wheel (right front wheel) 5-RL wheel (left rear wheel) 6-RR wheel (right rear wheel) 7- ( Brake device of FL wheel 8-Brake device of FR wheel 9-Speed sensor of FL wheel 10-Speed sensor of FR wheel 11-Speed sensor of RL wheel 12-Speed of RR wheel Sensor 13-ECU (Electronic control unit)

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-294225 (JP, A) JP-A-62-137258 (JP, A) JP-A-63-38064 (JP, A) 121965 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B60T ^7/ 12-8/96

Claims (2)

(57) [Claims] 1. A wheel speed detecting means for detecting a wheel speed of each wheel in a vehicle which transmits a generated torque of an engine to left and right driving wheels via a differential device, and the wheel speed detecting means detects the wheel speed. Reference speed creating means for creating a reference speed for the wheel speed, and each of the left and right drive wheels from the wheel speed detected by the wheel speed detecting means and the reference speed created by the reference speed creating means. Drive wheel slip detection means for detecting the slip state of
A slip control amount calculating means for calculating a slip control amount based on the slip state detected by the drive wheel slip detecting means; and the left and right drive wheels based on the slip control amount calculated by the slip control amount calculating means. A braking force adjusting means for independently adjusting the braking force applied to the vehicle, wherein a driving wheel speed difference between left and right driving wheels is calculated from a wheel speed detected by the wheel speed detecting device. Speed difference calculating means; and if the driving wheel speed difference calculated by the driving wheel speed difference calculating means is larger than a set value, the slip of the high-speed driving wheel is reduced.
High-speed wheel slip control amount that performs correction to increase the control amount
A correcting means, wherein the drive wheel speed difference is larger than the set value and the high speed side
Drive wheel speed reduction is greater in absolute value than another set value
If not, increase the slip control amount of the low-speed drive wheel.
A slip control device for a vehicle, comprising: a low-speed wheel slip control amount correction means for performing positive correction . 2. The vehicle slip control device according to claim 1, wherein the turning state detecting means for detecting a turning state of the vehicle, and the driving wheel speed difference based on the turning state detected by the turning state detecting means. And a driving wheel speed difference correcting means for correcting the driving wheel speed difference calculated by the calculating means.