JPH07228236A - Traction control device for vehicle - Google Patents

Abstract

PURPOSE:To properly correct a brake oil pressure changing quantity caused by mutual interference between low pressure side brake oil pressure and high pressure side brake oil pressure. CONSTITUTION:In a braking system for a rear wheel driving vehicle, pressure increasing valves 21 and 27, pressure reducing valves 24 and 29, bypass passages 25 and 30 and check valves 26 and 31 are arranged in branch oil pressure passages 8 and 9 leading to wheel cylinders 4 and 6 of left and right driving wheels from a common hydraulic pump 32 composed of a plunger pump, and a hydraulic accumulator is eliminated. In the case where pressure is increased to the low pressure side when differential pressure of oil pressure of the wheel cylinders 4 and 6 is not less than a specific value, since high pressure side oil pressure is reduced by accompanying pressure reduction and low pressure side oil pressure is increased, a control quantity of low pressure side TCS control is corrected so as to reduce the pressure, and a control quantity of high pressure side TCS control is corrected so as to increase the pressure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a traction control device for a vehicle, and in particular, when there is a difference in the brake hydraulic pressures of the left and right driving wheels, the fluctuation of the brake hydraulic pressure due to the mutual interference of the low-pressure side brake hydraulic pressure and the high-pressure side brake hydraulic pressure. It is related to what was made to correct.

[0002]

2. Description of the Related Art Conventionally, in order to prevent the driving wheels from slipping due to excessive driving torque and deteriorating the running performance during acceleration of a vehicle, a slip ratio or a slip amount of the driving wheels (this is called a slip value). ) Is detected and the engine driving force and the braking force for the wheels are controlled (the engine driving force is reduced or the braking force is increased) so that the slip value of the driving wheel becomes the target slip value. Traction control technology has been generally put to practical use.

For example, in Japanese Patent Laid-Open No. 170082/1993, in a traction control device for performing engine traction control and brake traction control, when the brake hydraulic pressure of the left and right drive wheels is equal to or higher than a predetermined pressure, the brake pressure increase amount on the high pressure side is set. It is described that the engine output is corrected to the reduction side while weakening or increasing the pressure reduction degree.

By the way, in a hydraulic system of a vehicle braking system to which brake traction control is applied, a branch hydraulic passage extending from a hydraulic supply source to a wheel cylinder of a brake mechanism of left and right driving wheels, and a branch hydraulic passage of these branch hydraulic passages. A pressure increasing valve and a pressure reducing valve connected to each are provided,
By controlling the pressure increasing valve and the pressure reducing valve, the brake hydraulic pressures of the left and right wheel cylinders are controlled. Furthermore, in the hydraulic system, in order to prevent the brake hydraulic pressure on the wheel cylinder side from being abnormally increased,
A check valve that allows passage of hydraulic pressure in the return direction may be provided in a bypass passage that bypasses each pressure increasing valve. Here, as the hydraulic pressure supply source, a hydraulic pump,
A hydraulic accumulator is generally provided, but the hydraulic accumulator may be omitted in some cases.

[0005]

In a hydraulic system of a vehicle braking system to which the brake traction control is applied, a bypass passage that bypasses each of the pressure increasing valves is provided.
Provided with a check valve that allows passage of hydraulic pressure in the return direction,
When the hydraulic supply source is a hydraulic pump including a plunger pump and the hydraulic accumulator is omitted, when the differential pressure of the brake hydraulic pressure between the left and right drive wheels is equal to or more than a predetermined value, and when the plunger pump is in the intake stroke. Since the hydraulic pressure of the hydraulic circuit drops for a moment, the following problems occur.

In order to increase the brake hydraulic pressure of the wheel cylinder on the low pressure side, when the pressure increasing valve on the low pressure side is opened,
The brake oil pressure on the high pressure side flows through the check valve in the return direction and propagates to the wheel cylinders via the pressure booster valve on the low pressure side, so the brake oil pressure on the low pressure side is lower than the brake oil pressure to be controlled by the brake traction control. There is also a phenomenon that the brake hydraulic pressure on the high pressure side becomes lower than the brake hydraulic pressure that is to be controlled by the brake traction control (this is referred to as decompression).
As a result, the accuracy and reliability of the brake traction control are reduced, and the running stability is reduced. An object of the present invention is to provide a traction control device for a vehicle that can appropriately correct a variation in brake hydraulic pressure due to mutual interference between low-pressure brake hydraulic pressure and high-pressure brake hydraulic pressure.

[0007]

According to a first aspect of the present invention, there is provided a traction control device for a vehicle, wherein a hydraulic system of a braking system includes:
A branch hydraulic passage branched from a single hydraulic supply source and connected to the wheel cylinders of the brake mechanisms for the left and right drive wheels, respectively, and a pressure increasing valve and a pressure reducing valve connected to each of these branch hydraulic passages. A brake traction that is connected to a bypass passage that bypasses each of the pressure valves and that has a check valve that allows passage of hydraulic pressure in the return direction, and that executes brake traction control so that the slip value of the drive wheels on the road surface becomes the target slip value. In a traction control device for a vehicle equipped with a control means, a difference between a hydraulic pressure detection means for detecting a brake hydraulic pressure of each of the left and right drive wheel brake mechanisms and a left and right brake hydraulic pressure detected by the hydraulic pressure detection means is a predetermined value or more. At this time, when increasing the low-pressure side brake hydraulic pressure through the pressure increasing valve, A control amount, the brake hydraulic pressure difference is that a reduced pressure correcting means for correcting the comparison to pressure decrease during normal less than a predetermined value.

Here, when the high-pressure side brake hydraulic pressure is increased via the pressure increasing valve during or immediately after the correction by the pressure reducing correction means, the valve opening control amount for the pressure increasing valve is compared with the normal time. A pressure increasing correction means for correcting the pressure to the pressure increasing side may be provided (claim 2 subordinate to claim 1). The hydraulic pressure supply source may be configured not to include an accumulator for accumulating brake hydraulic pressure (claim 2).
Claim 3) dependent on. The hydraulic pressure supply source may be constituted by a plunger pump (claim 4 dependent on claim 1 or claim 2).

According to another aspect of the present invention, there is provided a traction control device for a vehicle, wherein a hydraulic system of a braking system is provided with branch hydraulic passages branched from a single hydraulic supply source and respectively connected to wheel cylinders of a brake mechanism for left and right driving wheels. A pressure-increasing valve and a pressure-reducing valve connected to each of these branch hydraulic passages, and a check valve connected to a bypass passage bypassing each of the pressure-increasing valves to allow passage of hydraulic pressure in the return direction. In a traction control device for a vehicle equipped with a brake traction control means for executing a brake traction control so that the slip value for the road surface becomes a target slip value, a hydraulic pressure detecting means for detecting the brake hydraulic pressure of the brake mechanism of the left and right driving wheels, respectively. And the difference between the left and right brake oil pressures detected by the oil pressure detection means is equal to or more than a predetermined value. , When low pressure brake hydraulic pressure increase pressure and high pressure side brake hydraulic pressure increase pressure are commanded at approximately the same time, the low pressure side brake hydraulic pressure increase control signal is output, and then the high pressure side brake hydraulic pressure increase control signal is output. And an output control means for outputting.

According to a sixth aspect of the present invention, there is provided a traction control device for a vehicle, wherein a hydraulic system of a braking system is provided with branch hydraulic passages branched from a single hydraulic supply source and respectively connected to wheel cylinders of a brake mechanism for left and right driving wheels. A pressure-increasing valve and a pressure-reducing valve connected to each of these branch hydraulic passages, and a check valve connected to a bypass passage bypassing each of the pressure-increasing valves to allow passage of hydraulic pressure in the return direction. In a traction control device for a vehicle equipped with brake traction control means for executing brake traction control so that the slip value for the road surface becomes a target slip value, a hydraulic pressure detection for detecting the brake hydraulic pressure of the brake mechanism of the left and right drive wheels, respectively. Means and the left and right brake oil pressures detected by the oil pressure detection means are equal to or more than a predetermined value. At this time, when an instruction to increase the low-pressure side brake hydraulic pressure and an increase in the high-pressure side brake hydraulic pressure are issued at substantially the same time, the valve opening control amount for increasing the low-pressure side brake hydraulic pressure via the pressure increasing valve is set to the brake hydraulic pressure difference. If it is less than a predetermined value, it is corrected to the decompression side compared to the normal time, the control signal is output, and then the valve opening control amount that increases the brake hydraulic pressure on the high pressure side via the pressure increasing valve is increased on the pressure increase side compared to the normal time. Correction output means for correcting and outputting the control signal.

[0011]

In the traction control device for a vehicle according to the first aspect of the present invention, during execution of the brake traction control, when the pressure increasing valve of each branch hydraulic passage is opened and the pressure reducing valve is closed, the corresponding wheel cylinder The brake hydraulic pressure is increased, and conversely, when the pressure increasing valve is closed and the pressure reducing valve is open, the brake hydraulic pressure is reduced. A check valve that allows passage of hydraulic pressure in the return direction is provided in the bypass passage that bypasses each of the pressure boosting valves. Here, the hydraulic pressure detecting means detects the brake hydraulic pressures of the left and right drive wheels respectively, and the pressure reducing correction means, when the difference between the left and right brake hydraulic pressures detected by the hydraulic pressure detecting means is equal to or more than a predetermined value,
When the low-pressure side brake hydraulic pressure is increased via the pressure increasing valve, the valve opening control amount for the pressure increasing valve is corrected to the pressure reducing side as compared with the normal time when the brake hydraulic pressure difference is less than a predetermined value.

Therefore, when the low-pressure side brake hydraulic pressure is increased through the pressure increasing valve, the high-pressure side brake hydraulic pressure passes through the check valve in the bypass passage bypassing the high-pressure side pressure increasing valve, and the low-pressure side brake hydraulic pressure. Even if it is propagated to, the increase in the brake oil pressure can be corrected through the pressure reduction correction by the pressure reduction correction means. As a result, it is possible to prevent the accuracy and reliability of brake traction control from decreasing.
Driving stability can be secured.

In the traction control device for a vehicle according to a second aspect of the present invention, the pressure increase correction means, when the high pressure side brake oil pressure is increased via the pressure increase valve, at or immediately after the correction by the pressure reduction correction means. The valve opening control amount for the pressure increasing valve is corrected to the pressure increasing side as compared with the normal time. Therefore, since the brake hydraulic pressure on the high-pressure side can be corrected by the pressure increase correction by the pressure increase correction means, the decrease in the brake oil pressure decreased via the check valve can be corrected, and thus the accuracy and reliability of the brake traction control can be improved. It is possible to further prevent the deterioration, and to ensure traveling stability.
Further, in this way, the pressure reduction correction means and the pressure increase correction means
Since the low-pressure side brake hydraulic pressure and the high-pressure hydraulic pressure can be appropriately corrected, the hydraulic pressure supply source can be configured only by the hydraulic pump and the hydraulic accumulator can be omitted.

In the traction control device for a vehicle according to claim 3, the hydraulic pressure supply source does not include an accumulator for accumulating the brake hydraulic pressure, but as described in claim 2, the pressure reducing correction means and the pressure increasing correction means. With this, since the low-pressure side brake hydraulic pressure and the high-pressure hydraulic pressure can be appropriately corrected, there is no problem in controlling the brake hydraulic pressure, and the production cost can be reduced by omitting the accumulator. In the traction control device for a vehicle according to claim 4, the hydraulic pressure supply source is composed of a plunger pump, and even if a momentary hydraulic pressure drop occurs in each intake stroke of the plunger pump, the low-pressure side brake hydraulic pressure and There is no problem because the high pressure oil pressure can be corrected appropriately.

In the vehicle traction control device according to the fifth aspect, the same operation as in the first aspect can be obtained with respect to the premise configuration. The hydraulic pressure detection means detects the brake hydraulic pressures of the left and right drive wheels respectively.The output control means detects the low-side brake hydraulic pressure when the difference between the left and right brake hydraulic pressures detected by the hydraulic pressure detection means is equal to or more than a predetermined value. When the pressure increase command and the high pressure brake oil pressure increase command are issued at substantially the same time, the low pressure side brake oil pressure increase control signal is output, and then the high pressure side brake oil pressure increase control signal is output. Here, if the output of the pressure increase control signal for the low-pressure side brake hydraulic pressure and the output of the pressure increase control signal for the pressure-increasing side brake hydraulic pressure are executed simultaneously, the high-pressure side brake hydraulic pressure flows backward through the pressure increasing valve, but After outputting the side brake hydraulic pressure control signal,
By outputting the control signal of the high-pressure side brake hydraulic pressure, the low-pressure side brake hydraulic pressure and the high-pressure side brake hydraulic pressure can be controlled with high accuracy.

In the traction control device for a vehicle according to the sixth aspect, the same operation as the first aspect can be obtained with respect to the premise structure. The hydraulic pressure detecting means detects the brake hydraulic pressures of the brake mechanisms of the left and right drive wheels, respectively, and the correction output means detects the low-side brake hydraulic pressure when the difference between the left and right brake hydraulic pressures detected by the hydraulic pressure detecting means is equal to or more than a predetermined value. When the pressure increase and the pressure increase of the high-pressure side brake hydraulic pressure are commanded at approximately the same time, the valve opening control amount that increases the low-pressure side brake hydraulic pressure via the pressure increase valve is compared during normal times when the brake hydraulic pressure difference is less than the predetermined value. Then, the control signal is corrected to the pressure reducing side, the control signal is output, and then the valve opening control amount for increasing the brake hydraulic pressure on the high pressure side via the pressure increasing valve is corrected to the pressure increasing side by comparing with the normal time. Is output. The operation and effect of the correction on the pressure reducing side and the correction on the pressure increasing side are the same as those of the first and second aspects.

When the output of the control signal corrected to the pressure reducing side and the output of the control signal corrected to the pressure increasing side are simultaneously executed, the brake hydraulic pressure on the high pressure side flows backward through the pressure increasing valve, but the low pressure side. By outputting the control signal to the high pressure side after outputting the control signal to the
The brake hydraulic pressure on the high pressure side can be controlled with high accuracy.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. The present embodiment is an example of applying the present invention to a traction control device for a rear-wheel drive type vehicle. As shown in FIG. 1, this braking system BS basically includes a tandem master cylinder 2 operated by a brake pedal 1, a wheel cylinder 4 of a caliper of a brake mechanism for a left rear wheel 3, and a right rear wheel 5. Brake mechanism caliper wheel cylinder 6, master cylinder 2
A main hydraulic passage 7 extending from the main hydraulic passage 7, branch hydraulic passages 8 and 9 branched from the main hydraulic passage 7 at a branch point A and connected to wheel cylinders 4 and 6, respectively, and a wheel cylinder 12 of a caliper of a brake mechanism for the left front wheel 11. A wheel cylinder 14 of a caliper of a brake mechanism for the right front wheel 13, a main hydraulic passage 15 extending from the master cylinder 2, and a branch hydraulic passage 16 branched from the main hydraulic passage 15 at a branch point B and connected to the wheel cylinders 12 and 14, respectively. , 17
Is provided.

Further, the braking system BS includes a rear wheel ABS hydraulic system 20 and a front wheel ABS hydraulic system 40 for an anti-skid brake control system (ABS) and a rear wheel brake traction control system (TCS). TC
An S hydraulic system 60 and a pump drive motor 18 shared by the hydraulic systems 20, 40 and 60 are provided.

Next, the ABS hydraulic system 20 for the rear wheels will be described. A pressure increasing valve 21 is provided in the branch hydraulic passage 8, and a return oil passage 22 connected to the branch hydraulic passage 8 on the downstream side (wheel cylinder 4 side) of the pressure increasing valve 21 is connected to a reservoir 23. A pressure reducing valve 24 is provided in the return oil passage 22. In the bypass oil passage 25 that bypasses the pressure increasing valve 21, a check valve 26 that allows a hydraulic pressure flow from the wheel cylinder 4 in the returning direction.
Is provided.

Similarly, a pressure increasing valve 27 is provided in the branch hydraulic passage 9, and a return oil passage 28 connected to the branch hydraulic passage 9 on the downstream side of the pressure increasing valve 27 is a return oil passage 22. Connected to the reservoir 23 via the downstream part of
A pressure reducing valve 29 is provided in the return oil passage 28. Bypass oil passage 3 bypassing the pressure increasing valve 27
At 0, a check valve 31 that allows a hydraulic pressure flow from the wheel cylinder 6 in the returning direction is provided.

Hydraulic supply line 3 provided with a hydraulic pump 32
3 extends from the reservoir 23 and is connected to the branch point A of the main hydraulic passage 7 via the upstream side portion of the branch hydraulic passage 9, and the hydraulic supply passage 33 has check valves 34, The hydraulic pump 32, the check valve 35, the throttle valve 36, and the check valve 37 are connected. The hydraulic pump 32 is connected to the motor 18 and driven by the motor 18. The pressure increasing valves 21, 27
The pressure reducing valves 24 and 29 are duty solenoid valves capable of opening and closing the oil passage and finely adjusting the degree of valve opening. Further, a hydraulic pressure sensor 81 for detecting the brake hydraulic pressure of the wheel cylinder 4 is connected to the branch hydraulic pressure passage 8, and a hydraulic pressure sensor 82 for detecting the brake hydraulic pressure of the wheel cylinder 6 is connected to the branch hydraulic pressure passage 9. There is.

Next, the ABS hydraulic system 40 for the front wheels will be described. A pressure increasing valve 41 is provided in the branch hydraulic passage 16, and a return oil passage 42 connected to the branch hydraulic passage 16 on the downstream side of the pressure increasing valve 41 is connected to a reservoir 43. A pressure reducing valve 44 is provided. The bypass oil passage 45 that bypasses the pressure increasing valve 41 is provided with a check valve 46 that allows the hydraulic pressure to flow from the wheel cylinder 12 in the returning direction.
Similarly, the pressure increasing valve 47 is provided in the branch hydraulic passage 17.
The return oil passage 48 connected to the branch hydraulic passage 17 on the downstream side of the pressure increasing valve 47 is connected to the reservoir 43, and the return oil passage 48 is provided with a pressure reducing valve 49. The bypass oil passage 50 that bypasses the pressure increasing valve 47 is provided with a check valve 51 that allows a hydraulic pressure flow from the wheel cylinder 13 in the returning direction.

Hydraulic supply line 5 provided with a hydraulic pump 52
3 extends from the reservoir 43 and is connected to the branch point B of the main hydraulic passage 15 via the upstream side portion of the branch hydraulic passage 16. In the hydraulic supply passage 53, check valves 54, The hydraulic pump 52, the check valve 55, the throttle valve 56, and the check valve 57 are connected. The hydraulic pump 52 is connected to the motor 18 and driven by the motor 18. Booster valves 41, 47
The pressure reducing valves 44, 49 are duty solenoid valves capable of opening and closing the oil passage and finely adjusting the degree of valve opening.

Next, the rear wheel TCS hydraulic system 60 will be described. The main hydraulic passage 7 is provided with a cut valve 61 capable of opening and closing this passage.
The bypass oil passage 62 that bypasses 1 is provided with a check valve 63 that permits the flow of hydraulic pressure in the downstream direction, and the bypass oil passage 64 that bypasses the cut valve 61.
Is provided with a check valve 65 that allows a hydraulic pressure flow in the upstream direction when a hydraulic pressure higher than the brake hydraulic pressure generated during execution of the brake traction control is applied.

Further, a pressure increasing cylinder 66 is provided for increasing the hydraulic pressure in the main hydraulic pressure passage 7 when the brake traction control is executed. This pressure increasing cylinder 66
The discharge port 67 is connected to the main hydraulic passage 7 via the pressure increasing oil passage 68, and the input oil chamber 69 of the pressure increasing cylinder 66 is
It is connected to the reservoir 75 by a hydraulic pressure input passage 74 having a hydraulic pump 73, and the reservoir 7 is connected to the hydraulic pressure input passage 74.
Check valve 76, hydraulic pump 73,
A check valve 77 is provided, and the hydraulic pump 73
Is connected to a pump driving motor 18, and this motor 18
Driven by. Input oil chamber 69 of the pressure increasing cylinder 66
The return oil passage 78 connected to is connected to the reservoir 75,
The return oil passage 78 is provided with a control valve 79 capable of opening and closing the oil passage. Incidentally, reference numeral 80 is a relief valve that is operated by relief at a predetermined high hydraulic pressure, and the cut valve 61 and the control valve 79 are
It is an open / close solenoid valve.

A seal member 71 is attached to the piston 70 of the pressure increasing cylinder 66. This piston 7
0 is biased toward the input oil chamber 69 by the return spring 72, and when the oil pressure is supplied to the input oil chamber 69, the piston 70 moves in the discharge direction against the return spring 72 and the discharge port 67. The hydraulic pressure is discharged to the main hydraulic pressure passage 7. Control unit 10
Controls the various valves and the motor 18 to perform anti-skid brake control and brake traction control. The control unit 10 performs waveform shaping of various detection signals and A / D conversion. Circuit, an input / output interface, a microcomputer, a drive circuit for driving and controlling valves and the like.

The control unit 10 includes a motor 18, a cut valve 61, a control valve 79, pressure increasing valves 21, 27, 41, 47 and pressure reducing valves 24, 29, 4.
4 and 49 are electrically connected to each other, and the motor 18 and valves are controlled by the control unit 10. Further, although not shown, the control unit 10 includes hydraulic pressure sensors 81, 82.
In addition to the detection signal of the vehicle, various detection signals such as the wheel speed of four wheels of the vehicle, the steering angle, the brake switch signal, the engine speed, the throttle opening, the accelerator pedal depression amount, the mode switch signal for setting the traveling mode, etc. Based on the control program for receiving, anti-skid brake control, and the control program for brake traction control, anti-skid brake control during braking and the like and brake traction control during acceleration are executed. In the following explanation,
"ABS control" means anti-skid brake control,
Moreover, "TCS control" means brake traction control.

Since the anti-skid brake control is a general control, it will be briefly described. When each wheel (driving wheels 3 and 5 and driven wheels 11 and 13) is locked, mainly during braking. , Operate the motor 18,
Corresponding pressure reducing valve 2 of the S hydraulic system 20, 40
4,29,44,49 and booster valves 21,27,41,
A predetermined pattern of reducing, maintaining, and increasing the brake hydraulic pressure via 47 is repeated to control the slip amount to be equal to or less than the predetermined target slip amount for ABS control.

The brake traction control will be briefly described. When the slip amount (corresponding to the slip value) of the driving wheels becomes larger than the target slip amount for TCS control (corresponding to the target slip value), the motor 18 is operated. Is driven, the cut valve 61 and the control valve 79 are closed, the pressure increasing valves 21 and 27 are opened, the pressure reducing valves 24 and 29 are closed, and the hydraulic pressure is supplied from the pressure increasing cylinder 66 to the wheel cylinders 4 and 6 to apply the braking force. To strengthen
The brake hydraulic pressure is controlled so that the slip amount of the drive wheels becomes equal to or less than the TCS control target slip amount. However, actually, the brake traction control is individually executed for both the wheel cylinders 4 and 6.

Next, the main routine of the brake traction control will be described with reference to the flow charts of FIGS. In the figure, reference numeral Si (i = 1, 2, 3, ...
..) indicates each step, and this main routine is repeatedly executed at every predetermined minute time (for example, 50 ms). In FIG. 2, when control is started by starting the engine, slip amount detection processing is executed (S1), target slip amount setting processing is executed next (S2), and slip determination processing is executed next (S3). ), The throttle control target control amount calculation process is then executed (S4), the brake control target control amount calculation process is executed (S5), and the brake control target control amount correction process and control signal are then executed. Output processing is executed (S6), and then the process returns.

Next, each subroutine of S1 to S3 and S5 will be described. The throttle control target control amount calculation process of S4 is not directly related to the present application, and thus the description thereof is omitted. Slip amount detection process ... See FIG. 3. When the subroutine of this slip amount detection process is started, first, the wheel speeds V1 to V4 of the left and right front wheels 11, 13 and the rear wheels 3, 5 are read from the wheel speed sensor. Re (S1
0), then the vehicle speed V, which is the vehicle speed, is the left and right driven wheel speeds V
1 and V2 are calculated as an average value, and the maximum drive wheel speed Vm is calculated as a maximum value of the left and right drive wheel speeds V3 and V4 (S11). Next, at S12, the slip amount Se for throttle control and the slip amount S for left rear wheel brake control S
b1 and the right rear wheel brake control slip amount Sb2 are calculated by the equations shown, and the data of these slip amounts are stored in the work memory while being updated.

Target Slip Amount Setting Process (See FIG. 4) When the subroutine of the target slip amount setting process is started, various signals (road surface friction coefficient μ,
The vehicle speed V, the accelerator depression amount, the detected steering angle θ, the mode signal from the mode switch, etc.) are read (S20). Here, the road surface friction coefficient μ is calculated as follows based on the vehicle speed V and its acceleration Vg by an interrupt processing routine (not shown), and is updated every moment.

To calculate the road surface friction coefficient μ, 100 m
Using a timer for counting s and a timer for counting 500 ms, 1 is set every 100 ms from the start of slip control until 500 ms when the vehicle body acceleration Vg does not become sufficiently large.
The vehicle body acceleration Vg is calculated from the change of the vehicle speed V during 00 ms by the following equation (1), and after 500 ms when the vehicle body acceleration Vg becomes sufficiently large, 500 m is calculated every 100 ms.
From the change of the vehicle speed V during s, the vehicle body acceleration Vg is calculated by the following equation (2). Note that V (i) is currently V (i-10
0) is 100 ms before, V (i-500) is 500 ms before, and K1 and K2 are predetermined constants.
In addition, ms means msec.

Vg = K1 × [V (i) -V (i-100)] (1) Vg = K2 × [V (i) -V (i-500)] (2) The road surface friction coefficient μ is The vehicle speed V obtained as described above,
It is calculated by three-dimensional complementation from the μ table shown in Table 1 using the vehicle body acceleration Vg, and stored in the work memory while being updated.

[0036]

[Table 1]

Next, in S21, the map M0 of FIG.
By applying the road surface friction coefficient μ to the throttle control target slip amount basic value SETo and the brake control target slip amount basic value SBTo. As shown in the map M0, the basic value SETo is set smaller than the basic value SBTo because the engine traction control suppresses the slip when the slip amount is small and the engine traction is large when the slip amount is large. This is to prevent the load on the brake mechanism from increasing by suppressing the slip by the control and the brake traction control.

Next, coefficients k1 to correct the basic value SETo and the basic value SBTo according to the running condition of the vehicle.
k4 is calculated in S22 to S25. First, the vehicle speed V is applied to the map M1 of FIG. 9 to calculate the coefficient k1 (S22), and then the accelerator depression amount is applied to the map M2 of FIG. 10 to calculate the coefficient k2 (S23). Figure 11
The coefficient k3 is calculated by applying the steering angle θ to the map M3 of (S24), and then the coefficient k4 is calculated from the map M4 of FIG. 12 and the mode signal (S25). Next, in S26,
A coefficient KD obtained by multiplying the coefficients k1 to k4 is calculated (S2
6). Next, in S27, the target slip amount SET for throttle control is calculated as SET = basic value SETo × KD, the target slip amount SBT for brake control is calculated as SBT = basic value SBTo × KD, and these are stored in the work memory. Stored in.

Slip determination process: see FIG. 5. When the slip determination process is started, various signals (slip amounts Se, Sb1, Sb2, target slip amounts SET, SBT, etc.) are read (S30), Then, S31 ~ S
At 34, a slip flag Fe for identifying the necessity of engine traction control and a slip flag Fb1 for identifying the necessity of brake traction control for the left rear wheel 3
And a slip flag Fb2 for identifying the necessity of brake traction control for the right rear wheel 4 are set.

When Se> SET in S31,
Slip flag Fe is set to 1, and Se ≦ S
When the ET state continues for a predetermined time, the slip flag Fe is reset to 0. However, the determination of continuation for the predetermined time is actually made by setting a flag (not shown) and timing by a timer (not shown). next,
In S32, the slip flag Fb1 is set to 1 when Sb1> SBT, and the slip flag Fb1 is reset to 0 when Sb1 ≦ SBT. Then, when Sb2> SBT, the slip flag Fb2 is set to 1, and when Sb2 ≦ SBT, the slip flag Fb2 is reset to 0.

Next, it is judged whether or not the brake pedal is depressed to turn on the brake switch (S33), and when the brake switch is turned on, the slip flags Fb1 and Fb2 are reset to 0 (S34),
When the brake switch is off, the slip flags Fe, Fb1, Fb2 are maintained.

Target control amount calculation process for brake control ...
When this target control amount calculation process is started, various signals (slip amounts Sb1 and Sb2, target slip amount SBT, slip amounts Sb1 and Sb2, and slip amount deviation ENb1 (i-1 ), ENb2 (i-1), final target controlled variable FTA1
(i-1), FTA2 (i-1) and other data) are read (S5
0). The subscript "1" is the wheel cylinder 4 of the left rear wheel 3.
And valves 21 and 24, and the subscript “2” indicates the wheel cylinder 6 and valves 27 and 29 of the right rear wheel 5, and the subscript
(i-1) indicates the previous value, and the subscript (i) indicates the current value.

Next, in S51, the slip amount deviation E
N is the deviations ENb1 (i) and ENb2 (i) of this time, and the slip amount deviation change rate DEN is the deviation change rate DENb1 (i) of this time.
, DENb2 (i) are calculated according to the calculation formula shown.
Next, in S52, the current slip amount deviation ENb1 (i)
Then, this slip amount deviation change rate DENb1 (i) is applied to the table in Table 2 to calculate the basic control amount TA1 (i) this time, and this slip amount deviation ENb2 (i) and this time The slip amount deviation change rate DENb2 (i) of is applied to the table of Table 2 to calculate the basic control amount TA2 (i) of this time. next,
The basic control variables TA1 (i) and TA2 (i) are applied to the table of Table 3 respectively to quantify them (S53).

[0044]

[Table 2]

[Table 3]

Here, in the table of Table 2, ZO indicates the holding of the brake oil pressure, N indicates the increase of the brake oil pressure, P indicates the decrease of the brake oil pressure, and the subscripts S, M, B.
Indicates the magnitude of the control amount, S is “small control amount”, M
Indicates "medium control amount" and B indicates "large control amount". The numerical value excluding the positive and negative signs in Table 3 is the valve opening time (ms) for each 50 ms control cycle of the pressure increasing valves 21, 27 and the pressure reducing valves 24, 29, and this valve opening time is increased during pressure increase. When the pressure valves 21 and 27 are open and the pressure is reduced, the pressure reducing valve 2 is used.
4 and 29 show the valve opening time. The pressure reducing valves 24 and 29 are fully closed (valve opening time = 0) during pressure increase, and the pressure increasing valves 21 and 27 are fully closed (valve opening time = 0) during pressure reduction. Next, in S54, the final target control amount of this time
FTA1 (i) and FTA2 (i) are the basic control amounts TA1 (i), FTA1 (i), FTA1 (i-1), FTA2 (i-1) It is set as a value obtained by adding TA2 (i).

Target control amount correction process for brake control and control signal output process ... See FIG. 7. When this subroutine is started, various signals (detection signals from the hydraulic pressure sensors 81 and 82, final target control this time) are first displayed. Quantity FTA1 (i), FTA2 (i)
Data, etc.) are read (S60). The final target control amounts FTA1 (i) and FTA2 (i) correspond to the valve opening control amount. Next, it is determined whether the differential pressure ΔP, which is the absolute value of the difference between the brake hydraulic pressures P1 and P2 detected by the hydraulic pressure sensors 81 and 82, is greater than or equal to a predetermined value C (S61). If the determination is Yes, the process proceeds to S63. If the determination is No, the process proceeds to S62.

Here, of the final target control amounts FTA1 (i) and FTA2 (i) of this time, the final target control amount on the low-pressure side of the brake oil pressure is FTAL and the brake oil pressure is high pressure for the sake of convenience of the following description. The final target controlled variable on the side is FTAH. S61
If the differential pressure ΔP <predetermined value C as a result of the determination, it is not necessary to correct the final target control amount this time, so a control signal based on the final target control amounts FTAL, FTAH is output in S62, and then the process returns. . When ΔP ≧ predetermined value C, it is determined in S63 based on the data of the final target control amount FTAL on the low pressure side whether or not the low pressure side is pressure-increased, that is, whether or not a command is issued to increase the brake hydraulic pressure on the low-pressure side, When the determination is No, the process proceeds to S62.

Here, when the pressure on the low pressure side is increased, the pressure increase valve 21 or 27 on the low pressure side is opened for the valve opening time designated by the final target control amount FTAL. Through the check valve 31 or 26 that bypasses the pressure increasing valve 27 or 21 on the high pressure side, a part of the brake hydraulic pressure on the high pressure side flows in the return direction, and the brake hydraulic pressure on the low pressure side increases by the return amount of the hydraulic pressure. , The brake hydraulic pressure on the high pressure side drops. However, since the hydraulic pump 32 is composed of a plunger pump, and the hydraulic pressure in the main hydraulic passage 7 drops for a moment at each moment when the plunger pump is out of the discharge stroke, the brake hydraulic pressure on the high pressure side is the check valve 31 or 26. Flows in the direction of return.

Therefore, as a result of the determination in S63, when the low pressure side is increased, the final target control amount FTAL is changed to FTAL / FTAL in S64 in order to correct the pressure increase of the low pressure side brake hydraulic pressure. It is corrected to (1 + K × ΔP). still,
K is a predetermined constant, and 0 <K × ΔP <1. Next, in S65, a control signal based on the final target control amount FTAL on the low voltage side is output, and then the timer T is started (S66). Next, in S67, based on the data of the final target control amount FTAH on the high pressure side, it is determined whether or not the high pressure side is pressure-increasing, that is, whether or not a command is issued to increase the brake hydraulic pressure on the high pressure side. When Yes, in order to correct the increase in the above-mentioned decrease in the brake hydraulic pressure on the high pressure side, S
68, the final target controlled variable FTAH on the high voltage side is FTAH ×
The value is corrected to (1 + K × ΔP), and then the process proceeds to S72.

On the other hand, if the determination in S67 is No, S
At 69, it is judged whether the high pressure side is depressurized or not.
At the time of s, that is, when the high-pressure side brake hydraulic pressure is reduced, in S70, the high-pressure side final target control amount FT is set in order to correct the decrease in the high-pressure side brake hydraulic pressure.
AH is corrected to FTAH × (1-K × ΔP), then S7
Move to 3. On the other hand, when the determination in S69 is No, that is, when the brake hydraulic pressure on the high pressure side is maintained, the final target control amount FTAH set in S54 in FIG. In order to correct the decrease in the brake hydraulic pressure, the final target control amount is increased in S71.
FTAH = K × ΔP is set, and then the process proceeds to S72.

In S72, the time T measured by the timer T is about 25 ms so that the predetermined time δ (where δ is 20 ms (maximum valve opening time) <δ <50 ms-20 ms (maximum valve opening time)). Is greater than or equal to) and waits until T ≧ δ, and when T ≧ δ, S7
After shifting to 3, a control signal based on the final target control amount FTAH is output, and then the process returns. Incidentally, the above S62, S6
5, the output of the control signal in S73, the flags Sb1, S
It is executed under the condition that b2 = 1, and FIG.
Although not shown in the flowchart of FIG. 3, the control signal for engine traction control is also output to the engine control device (not shown) based on the final target control amount for throttle control, on condition that the flag Fe = 1.

The functions of the rear wheel ABS hydraulic system 20, the rear wheel TCS hydraulic system 60, and the brake traction control described above will be described. In a state where the ABS control and the brake traction control are not executed, the cut valve 61 and the pressure increasing valves 21 and 27 are held in the open position,
Since the pressure reducing valves 24 and 29 are held in the closed position,
When the brake pedal 1 is depressed, the brake hydraulic pressure generated in the master cylinder 2 is supplied to the wheel cylinders 4 and 6 via the main hydraulic pressure passage 7 and the branch hydraulic pressure passages 8 and 9. When the brake traction control is started, the motor 18 is driven, the hydraulic pumps 32, 52, 73 are driven, and the cut valve 61 and the control valve 7 are driven.
9 is closed, the increased brake hydraulic pressure is supplied from the pressure increasing cylinder 66, and is supplied to the wheel cylinders 4 and 6 through the pressure increasing valves 21 and 27.

Here, the hydraulic system 20, 60 is not provided with a hydraulic accumulator, and the hydraulic pump 32
Is composed of a plunger pump, and due to the characteristics of the plunger pump, the discharge pressure of the hydraulic pump 32 decreases for a moment at every moment when the hydraulic pump 32 is in a stroke other than the discharge stroke, and the hydraulic pressure in the main hydraulic passage 7 also momentarily increases. descend. The brake traction control is executed independently for the left and right drive wheels 3 and 5, so that the T
When the CS control is executed, the left and right wheel cylinders 4,
There are many cases where the brake hydraulic pressures of 6 are different. For example, the brake hydraulic pressure P1 of the wheel cylinder 4 of the left drive wheel 3 is high and the wheel cylinder 6 of the right drive wheel 5 is
It is assumed that the brake hydraulic pressure P2 becomes low and the differential pressure ΔP between these brake hydraulic pressures becomes equal to or higher than the predetermined value C.

When the pressure increasing valve 27 is opened in order to increase the brake hydraulic pressure of the wheel cylinder 6, even if the pressure increasing valve 21 is in the closed position, a check is made at the moment when the hydraulic pressure in the main hydraulic pressure passage 7 decreases. The brake hydraulic pressure on the high-pressure side flows backward from the valve 26, the brake hydraulic pressure of the wheel cylinder 4 slightly decreases (this phenomenon is referred to as “compression reduction”), and the brake hydraulic pressure of the wheel cylinder 6 slightly increases. Therefore, in the brake traction control of the present application, when the differential pressure ΔP is equal to or higher than the predetermined value C and the low pressure side is increased, the low pressure side brake hydraulic pressure is corrected in the pressure reducing direction as described with reference to the flowchart of FIG. 7. And again
The brake hydraulic pressure on the high pressure side was corrected in the increasing direction.

That is, when increasing the pressure on the low pressure side, S64
In, the final target control amount FTAL is corrected to the pressure reducing side, and the brake hydraulic pressure on the low pressure side can be precisely controlled through the pressure reducing correction (see (a) of FIG. 13). When increasing both the low-pressure side and the high-pressure side, the same applies to the low-pressure side as described above, but for the high-pressure side, the final target control amount FTAH is increased in S68 in order to correct the increase in the reduced pressure amount. The pressure can be corrected to the pressure side, and the brake hydraulic pressure on the high pressure side can be precisely controlled through the pressure increase correction (see FIG. 13B). Moreover, after the control signal based on the final target control amount FTAL is output through steps S66 and S72, the final target control amount is reached after a predetermined time δ has elapsed.
Since the control signal based on FTAH is output, by opening the pressure increasing valve on the high pressure side after closing the pressure increasing valve on the low pressure side,
When increasing the brake hydraulic pressure on the high pressure side, it is possible to prevent a decrease in hydraulic pressure due to reverse flow from the pressure increasing valve on the high pressure side.

Further, when increasing the pressure on the low pressure side and decreasing the pressure on the high pressure side, as shown in S70, since the decompressed amount is corrected to increase, the brake hydraulic pressure on the high pressure side can be precisely controlled. it can. However, in this case, since the pressure reducing valve is opened without opening the pressure increasing valve on the high pressure side, it is not necessary to step S72 (see (c) of FIG. 13). Further, when the low pressure side is increased and the high pressure side is maintained, in step S71, the reduced pressure amount is corrected to be increased, so that the high pressure side brake hydraulic pressure can be precisely controlled. However, in this case,
Since the pressure increasing valve is opened to increase the pressure, step S72 is performed to prevent a decrease in hydraulic pressure due to reverse flow from the pressure increasing valve when increasing the brake hydraulic pressure on the high pressure side (FIG. 1).
3 (d)).

Next, various modifications of the above embodiment will be described. 1] The routine of FIG. 7 in the above-described embodiment controls the pressure increasing valve 21 and the pressure reducing valve 27 for the braking mechanism of the left drive wheel 3, and the pressure increasing valve 27 and the pressure reduction for the braking mechanism of the right drive wheel 5. Since the control for the valve 29 is processed by the common routine shown in FIG.
If Yes in S63 and Yes in S67,
This corresponds to the case where the pressure increase of the low pressure side brake hydraulic pressure and the pressure increase of the high pressure side brake hydraulic pressure are commanded at substantially the same time.

However, the pressure increasing valve 21 and the pressure reducing valve 2
7, control of pressure increase valve 27 and pressure reduction valve 29
It is also possible to process the control with respect to a separate routine, in which case, in the same manner as in the above-described embodiment, the final target control amount FTAL on the low pressure side is decompressed and a control signal is output to output the control signal. For a predetermined time (for example, 50 ms of the control cycle) from the output (that is, immediately after the output of the control signal)
In addition, when the brake hydraulic pressure on the high pressure side is increased, the final target control amount FTAH on the high pressure side is increased and corrected in the same manner as in the above embodiment in order to increase and correct the decompressed amount.

Further, as described above, in the case where the processing is carried out in different routines, if the pressure increase of the low-pressure side brake hydraulic pressure and the pressure increase of the high-pressure side brake hydraulic pressure are commanded at substantially the same time, Similarly to, the final target controlled variable FT on the low voltage side
It is assumed that AL is decompressed and corrected, and the control signal is output, and then the final target control amount FTAH on the high-voltage side is increased and corrected, and the control signal is output.

2] In S64 of FIG. 7 of the above embodiment, the final target control amount FTAL is reduced by a predetermined amount ΔT,
The final target control amount FTAL may be decompressed and corrected.
At 68, the predetermined target amount ΔT is added to the final target control amount FTAH.
May be added, the predetermined amount ΔT may be subtracted from the final target control amount FTAH in S70, and the final target control amount FTAH may be set to the predetermined amount ΔT in S71. Good.

3] In the above embodiment, the oil pressure sensor 81,
Although the brake hydraulic pressure is detected by 82, the hydraulic pressure sensors 81 and 82 are omitted, and the cumulative value of the open time of the pressure increasing valve 21 and the cumulative value of the open time of the pressure reducing valve 24 during the execution of the brake traction control are calculated. Based on this, the brake hydraulic pressure of the wheel cylinder 4 is estimated, and similarly, the pressure increasing valve 27 during the execution of the brake traction control is also performed.
The brake hydraulic pressure of the wheel cylinder 4 may be estimated on the basis of the cumulative value of the open time and the cumulative value of the open time of the pressure reducing valve 29. 4] The above embodiment is an example in which the present invention is applied to a braking system of a rear wheel drive type vehicle, but the present invention can be similarly applied to a braking system of a front wheel drive type vehicle.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a traction control device for a vehicle according to an embodiment.

FIG. 2 is a flowchart of a main routine of traction control.

FIG. 3 is a flowchart of a subroutine of slip amount detection processing.

FIG. 4 is a flowchart of a subroutine of target slip amount setting processing.

FIG. 5 is a flowchart of a subroutine of slip determination processing.

FIG. 6 is a flowchart of a subroutine of target control amount calculation processing for brake control.

FIG. 7 is a flowchart of a subroutine of a target control amount correction process for brake control and a control signal output process.

FIG. 8 is a diagram showing a map M0.

FIG. 9 is a diagram showing a map M1.

FIG. 10 is a diagram showing a map M2.

FIG. 11 is a diagram showing a map M3.

FIG. 12 is a chart showing a map M4.

FIG. 13 is a time chart of command signals and execution signals of control amounts for the pressure increasing valve and the pressure reducing valve.

[Explanation of symbols]

 3,5 Rear wheel (driving wheel) 4,6 Wheel cylinder 7 Main hydraulic passage 8,9 Branch hydraulic passage 10 Control unit 20 ABS hydraulic system for driving wheel 21,27 Pressure increasing valve 24,29 Pressure reducing valve 25,30 Bypass passage 26, 31 Check valve 32 Hydraulic pump (hydraulic power supply source) 60 Drive wheel TCS hydraulic system 81, 82 Hydraulic sensor

Claims (6)

[Claims] 1. A hydraulic system of a braking system, a branch hydraulic passage branched from a single hydraulic supply source and respectively connected to a wheel cylinder of a brake mechanism for left and right driving wheels, and each of these branched hydraulic passages. Equipped with a built-in pressure increasing valve and pressure reducing valve, and a check valve connected to a bypass passage bypassing each of the pressure increasing valves to allow passage of hydraulic pressure in the return direction. In a traction control device of a vehicle equipped with a brake traction control means for performing brake traction control so that the brake hydraulic pressures of the brake mechanisms of the left and right drive wheels are respectively detected, and the hydraulic pressure detection means detects the hydraulic pressure. When the difference between the left and right brake oil pressures exceeds a specified value, the low-pressure side brake oil pressures When increasing the pressure, there is provided a pressure reducing correction means for correcting the valve opening control amount for the pressure increasing valve to a pressure reducing side in comparison with a normal time when the brake hydraulic pressure difference is less than a predetermined value. Traction control device. 2. When the high-pressure brake hydraulic pressure is increased via the pressure increasing valve during or immediately after the correction by the pressure reducing correction means, the valve opening control amount for the pressure increasing valve is compared with that in the normal time. The characteristic control device for a vehicle according to claim 1, further comprising a pressure increase correction unit that corrects pressure to the pressure increase side. 3. The traction control device for a vehicle according to claim 2, wherein the hydraulic pressure supply source does not include an accumulator for accumulating brake hydraulic pressure. 4. The traction control device for a vehicle according to claim 1, wherein the hydraulic pressure supply source is configured by a plunger pump. 5. A branch hydraulic passage connected to a wheel system of a brake mechanism of left and right drive wheels respectively branched from a single hydraulic supply source in a hydraulic system of a braking system, and each of these branched hydraulic passages. Equipped with a built-in pressure increasing valve and pressure reducing valve, and a check valve connected to a bypass passage bypassing each of the pressure increasing valves to allow passage of hydraulic pressure in the return direction. In a traction control device of a vehicle equipped with a brake traction control means for performing brake traction control so that the brake hydraulic pressures of the brake mechanisms of the left and right drive wheels are respectively detected, and the hydraulic pressure detection means detects the hydraulic pressure. When the difference between the left and right brake oil pressures exceeds a specified value, the low pressure brake oil pressure increase and high pressure brake Output control means for outputting a pressure increase control signal for the low-pressure side brake hydraulic pressure and then outputting a pressure increase control signal for the high-pressure side brake hydraulic pressure when the pressure increase of the hydraulic pressure is instructed at substantially the same time. Vehicle traction control device characterized by the above. 6. A hydraulic system of a braking system, branch hydraulic passages branched from a single hydraulic supply source and respectively connected to wheel cylinders of brake mechanisms of left and right driving wheels, and each of these branched hydraulic passages. Equipped with a built-in pressure increasing valve and pressure reducing valve, and a check valve connected to a bypass passage bypassing each of the pressure increasing valves to allow passage of hydraulic pressure in the return direction. In a traction control device of a vehicle equipped with a brake traction control means for performing brake traction control so that the brake hydraulic pressures of the brake mechanisms of the left and right drive wheels are respectively detected, and the hydraulic pressure detection means detects the hydraulic pressure. When the difference between the left and right brake oil pressures exceeds a specified value, the low pressure brake oil pressure increase and high pressure brake When the command to increase the hydraulic pressure is issued at approximately the same time, the valve opening control amount that increases the low-pressure brake hydraulic pressure via the pressure-increasing valve is changed to the depressurizing side by comparing the normal value when the brake hydraulic pressure difference is less than the predetermined value. After correcting and outputting the control signal, the valve opening control amount for increasing the high-pressure side brake hydraulic pressure through the pressure increasing valve is compared to the normal time and corrected to the pressure increasing side, and the control signal is used as the correction output means. A traction control device for a vehicle, comprising: