JP3480084B2 - Braking force distribution 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 braking force distribution control device for adjusting a braking force of a wheel behind a vehicle to a predetermined relationship with a braking force of a wheel in front of a vehicle during vehicle braking.

[0002]

2. Description of the Related Art Generally, when a braking operation is performed on a running vehicle, the axial load in the front and rear of the vehicle is different due to the load movement,
The braking force for the wheels in front of the vehicle and the braking force for the wheels on the rear that are necessary for the four wheels to lock at the same time are not in a direct proportional relationship, and are in a relationship called ideal braking force distribution. It also depends on

In this regard, if the braking force applied to the rear wheels exceeds the braking force applied to the front wheels, the directional stability of the vehicle is impaired. Therefore, in order to make the braking force distribution as close as possible to the ideal braking force distribution while keeping it lower than this. A proportional pressure reducing valve, a so-called proportioning valve, is provided between the wheel cylinder and the master cylinder. According to this, the distribution line has a break point, but considering the load difference between the inner and outer wheels when turning, it is necessary to keep the braking force on the rear wheel considerably lower than the braking force on the front wheel.
However, if the brake fluid pressure is always limited via the proportioning valve, the distribution of the braking force to the wheels behind the vehicle is reduced, and a large brake pedal force is required to obtain the predetermined deceleration, and The burden on the braking device for the wheels of the vehicle becomes large.

In order to solve such a problem, JP-A-6-
In JP-A-144174, a switching valve is provided upstream of a hydraulic booster and a hydraulic control valve provided between a master cylinder and a wheel cylinder, and the switching valve is switched and the hydraulic control valve is controlled. There has been proposed a braking force distribution control device that adjusts the brake fluid pressure of the rear wheel wheel cylinder to a predetermined relationship by doing so.

[0005]

Originally, in the ideal braking state, the front and rear wheels are simultaneously controlled, and the braking force is controlled so that the slip ratio becomes the same. However, when the vehicle turns, the load moves to the front wheels and the cornering force of the front wheels increases, resulting in a so-called oversteering tendency. Therefore, the same slip ratio control for four wheels at the same time may impair the stability of the vehicle. In the device described in JP-A-6-144174 or the like, the braking force of the rear wheels can be approximated to the ideal braking force distribution, so that good braking characteristics can be obtained during braking while the vehicle is traveling straight. When braking while the vehicle is turning, the cornering force with respect to the front wheels increases, and there is a risk of oversteering and deterioration of vehicle stability.

For example, as shown in FIG. 10, when a moment To is applied while the vehicle is turning, when a braking force is further applied, the moment increases and the steering characteristics change (oversteering tendency). At this time, the vehicle body side slip angle β that represents the vehicle body slip with respect to the traveling direction of the vehicle as an angle
Since the side slip angular velocity dβ / dt, which is a differential value thereof, becomes large at the time of oversteer, the vehicle body side slip angle β and the side slip angular velocity dβ / dt are monitored, and the braking force on each wheel is adjusted so as to cancel them. If controlled, the unnecessary moment ΔTs can be canceled, and stable steering characteristics can be secured.

In view of the above, the present invention provides a braking force distribution control device for adjusting the braking force of the wheels on the rear side of the vehicle. By performing the braking force distribution control according to the vehicle side slip angle, the braking force is stable even during braking while the vehicle is turning. The purpose is to perform appropriate braking operation while maintaining steering characteristics.

[0008]

In order to achieve the above object, the braking force distribution control device according to claim 1 is mounted on a wheel FW in front of the vehicle as shown in the outline of the configuration in FIG. A front wheel wheel cylinder Wf that applies a braking force and a rear wheel wheel cylinder Wr that is attached to a wheel RW on the rear side of the vehicle to apply a braking force, and a brake fluid is boosted in accordance with an operation of a brake pedal BP, and the front wheel and the rear wheel. A hydraulic pressure generator PG that applies a brake hydraulic pressure to each of the vehicle wheel cylinders Wf and Wr, and is interposed between the hydraulic pressure generator PG and at least the rear wheel wheel cylinder Wr to control the brake hydraulic pressure. Hydraulic pressure control device FV and lateral load for detecting the lateral acceleration of the vehicle
Speed detection means YS and detection of the lateral acceleration detection means YS
Based on the result, the vehicle side slip angle calculating means SA for converting the slip amount with respect to the traveling direction of the vehicle into an angle to calculate the vehicle side slip angle, and the hydraulic pressure control device FV are driven according to the calculation result of the vehicle side slip angle calculating means SA. However, the driving means AM for adjusting the braking force of the wheel RW on the rear side of the vehicle to the predetermined force with respect to the braking force of the wheel FW on the front side of the vehicle is provided.

The lateral acceleration detecting means YS calculates the estimated vehicle body speed of the vehicle on the basis of the detection output of the wheel speed detecting means WS, and obtains the lateral acceleration of the vehicle from the difference between the estimated vehicle body speed and the wheel speed. It can also be configured.

Further, as described in claim 2 , the side of the vehicle is
Lateral acceleration detecting means YS for detecting acceleration and this lateral acceleration
Based on the detection result of the degree detecting means YS, the vehicle body side slip angle calculating means SA for converting the amount of slip in the traveling direction of the vehicle into an angle to calculate the vehicle body side slip angle, and the wheel FW in front of the vehicle.
And wheel speed detecting means WS for detecting the wheel speed of each wheel RW on the rear side of the vehicle, and the slip ratio of each wheel RW on the rear side of the vehicle with respect to each wheel FW on the front side of the vehicle based on the detection output of this wheel speed detecting means WS. And a target slip ratio setting unit TS that corrects the slip ratio calculated by the slip ratio calculation unit SC based on the calculation result of the sideslip angle calculation unit SA to set the target slip ratio. This target slip ratio setting means TS
The control mode setting means CM for setting the control mode on the basis of the target slip ratio set by, and the hydraulic pressure control device FV in accordance with the control mode set by the control mode setting means CM are used to drive the wheels RW behind the vehicle. Driving means AM for adjusting the braking force to a predetermined relationship with the braking force of the wheels FW in front of the vehicle.
It is good to have and. The side slip angular velocity, which is the differential value of the vehicle side slip angle, may also be used for setting the target slip ratio.

[0011]

In the braking force distribution control device having the above-mentioned structure, when the brake pedal BP is operated, the brake fluid is supplied from the hydraulic pressure generator PG to each of the front and rear wheel wheel cylinders Wf and Wr. Pressure is supplied and braking force is applied to each wheel FW, RW, but a hydraulic pressure control device FV is interposed between the hydraulic pressure generation device PG and at least the rear wheel wheel cylinder Wr. The hydraulic pressure control device FV controls the brake hydraulic pressure applied to the rear wheel wheel cylinder Wr. In this case, the horizontal pressure
The lateral acceleration of the vehicle is detected by the speed detecting means YS,
Based on the detection result, the vehicle side slip angle calculating means SA
First, the side slip angular velocity, which is the differential value of the side slip angle of the vehicle body.
(Dβ / dt) is calculated, this is integrated over time, and
The sideslip angle (β) is determined. Thus fluid pressure control device FV according to the vehicle slip angle calculated by the vehicle slip angle calculating means SA is driven, the vehicle rear wheels R
The braking force of W is adjusted so as to have a predetermined relationship with the braking force of the wheels FW in front of the vehicle, that is, to approximate the ideal braking force distribution. As a result, the oversteer / understeer characteristics do not change significantly even during braking while the vehicle is turning, sufficient cornering force is secured for the rear wheels RW, and vehicle stability is maintained.

[0012]

In the braking force distribution control device according to the second aspect, the lateral acceleration of the vehicle is detected by the lateral acceleration detecting means YS.
Is detected, and based on the detection result
First, the calculating means SA calculates the lateral value which is the differential value of the vehicle side slip angle.
The slip angular velocity (dβ / dt) is calculated, and this is the time product.
Then, the vehicle side slip angle (β) is calculated. like this
In addition, the vehicle body side slip angle calculating means SA calculates the vehicle body side slip angle, and the wheel speed detecting means WS detects the wheel speeds of the front wheel FW and the rear wheel RW of the vehicle, respectively, and the slip ratio calculating means SC. The slip ratio of the vehicle rear wheel RW with respect to the vehicle front wheel FW is calculated based on the detection output of the wheel speed detection means WS.
Then, the target slip ratio setting unit TS corrects the slip ratio based on the calculation result of the vehicle body side slip angle calculating unit SA to set the target slip ratio. Then, the control mode setting means CM sets the control mode based on the target slip ratio, and the driving means AM drives the hydraulic pressure control device FV in accordance with the control mode. Thus, the braking force of the wheel RW on the rear side of the vehicle is adjusted to have a predetermined relationship with the braking force of the wheel FW on the front side of the vehicle while maintaining a stable steering characteristic even during braking while the vehicle is turning.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 shows an embodiment of a braking control device including a braking force distribution control device of the present invention, which is provided with a master cylinder MC and a regulator RG that constitute the hydraulic pressure generation device of the present invention, and these are the brake pedal BP. It is driven according to the operation. An auxiliary hydraulic pressure source AP is connected to the regulator RG, and these are connected to the low pressure reservoir RS together with the master cylinder MC. The auxiliary hydraulic pressure source AP has a hydraulic pump HP and an accumulator ACC. The hydraulic pump HP is driven by an electric motor (not shown), pressurizes and outputs the brake fluid in the low pressure reservoir RS, and the brake fluid is accumulator ACC via the check valve CV1.
Is supplied to and accumulated in pressure. Thus, accumulator AC
So-called power hydraulic pressure is appropriately supplied from C to the regulator RG. The electric motor is driven in response to the hydraulic pressure in the accumulator ACC falling below a predetermined lower limit value, and is stopped in response to the hydraulic pressure in the accumulator ACC exceeding a predetermined upper limit value.

The regulator RG receives the output hydraulic pressure of the auxiliary hydraulic pressure source AP, uses the output hydraulic pressure of the master cylinder MC as a pilot pressure, and regulates the regulator hydraulic pressure in proportion to the pilot hydraulic pressure. Since it is disclosed in Japanese Patent Publication No. 476664, detailed description will be omitted. The regulator RG of the present embodiment is configured to adjust the control hydraulic pressure to a predetermined ratio with respect to the output brake hydraulic pressure of the master cylinder MC (that is, the pressure proportional to the output brake hydraulic pressure of the master cylinder MC). The regulator RG can be configured separately from the master cylinder MC. Also,
Instead of the regulator RG, a hydraulic booster may be used in the hydraulic pressure generator of the present invention.

On the other hand, wheel cylinders Wfl, Wfr, Wrl, Wrr are mounted on the wheels FL, FR, RL, RR, respectively, and a hydraulic pressure passage connecting the master cylinder MC and each of the wheel cylinders Wfl, Wfr in front of the vehicle. The first valve device EV1 to the sixth valve device EV6 are interposed in the. Further, the seventh valve device EV7 to the tenth valve device EV10 and the proportional pressure reducing valve P are provided in the hydraulic passages connecting the regulator RG and the wheel cylinders Wrl, Wrr on the rear side of the vehicle.
V is installed. These first valve devices EV1 to ninth
The fluid pressure control device according to the present invention is configured by the valve device EV9, and the tenth valve device EV10 corresponds to the valve device of the present invention. In addition, the wheel FL indicates the wheel on the front left side when viewed from the driver's seat, hereinafter the wheel FR indicates the front right side, the wheel RL indicates the rear left side, and the wheel RR indicates the rear right wheel. As is clear from FIG. In the example, the front and rear pipes are divided into a hydraulic control system for the front wheels and a hydraulic control system for the rear wheels.
A so-called X pipe may be used. Further, in this embodiment, the wheels RL, RR on the rear side of the vehicle are drive wheels and the wheels FL, FR on the front side are so-called rear wheel drive related wheels, but they may be front wheel drive.

In the front wheel hydraulic system, the master cylinder M
The first valve device EV1 and the second valve device EV2 are respectively provided in the hydraulic paths that connect C and the wheel cylinders Wfl and Wfr on the front wheel side.
Are installed in the control passage Pfl,
The fifth valve device EV5 and the sixth valve device E are respectively connected via Pfr.
It is connected to V6. The fifth valve device EV5 and the sixth valve device EV6 are further connected to the third valve device EV4 via the fourth valve device EV4.
It is connected to the valve device EV3 and communicates with the regulator RG or the accumulator ACC. The first valve device EV1 and the second valve device EV2 are 3-port / 2-position electromagnetic switching valves, which are in the first position shown in FIG. 1 in a non-operating state, and the wheel cylinders Wfl and Wfr are both connected to the master cylinder MC. However, when the solenoid coil is excited and switched to the second position, the wheel cylinders Wfl and Wfr are both disconnected from the master cylinder MC, and the wheel cylinders Wfl and Wfr are respectively in the fifth position.
It communicates with the valve device EV5 and the sixth valve device EV6.

The third valve device EV3 and the fourth valve device EV4 are also 3-port / 2-position electromagnetic switching valves, and the third valve device EV3
Disconnects the fourth valve device EV4 and the proportional pressure reducing valve PV from the regulator RG in the first position in the non-operating state, and disconnects the fourth valve device EV4 and the proportional pressure reducing valve PV from the regulator RG in the second position in the operating state. Communication with the accumulator ACC. The fourth valve device EV4 communicates the third valve device EV3 with the fifth valve device EV5 and the sixth valve device EV6 in the first position in the non-actuated state, and disconnects these communication in the second position in the actuated state. , The fifth valve device EV5 and the sixth valve device EV6 communicate with the low pressure reservoir RS.

On the other hand, both the fifth valve device EV5 and the sixth valve device EV6 are 2-port / 2-position electromagnetic on-off valves, which are in the open position as shown in FIG. Then, the valve is closed and the hydraulic passage is shut off. The check valve CV2 and the throttle passage OR1 are connected in parallel to the fourth valve device EV4 and the fifth valve device EV5, and the check valve C4 is parallel to the fourth valve device EV4 and the sixth valve device EV6. The CV3 and the throttle passage OR2 are connected to each other, the inflow side of the check valve CV2 is connected to the control passage Pfl, and the inflow side of the check valve CV3 is connected to the control passage Pfr.

The throttle passage OR1 is provided with the first valve device EV3 when the third valve device EV3 is inactive when the brake pedal BP is operated.
When the first, fourth, and fifth valve devices EV4, EV5 are activated, the brake fluid from the regulator RG is provided to gently flow into the wheel cylinder Wfl. Is also the same. Further, the check valve CV2 causes the brake fluid pressure of the wheel cylinder Wfl to quickly follow the decrease in the output fluid pressure of the regulator RG when the brake pedal BP is released when the first valve device EV1 is in the operating state. It is provided for the purpose of allowing the flow of the brake fluid in the direction of the third valve device EV3 and blocking the flow in the opposite direction.
The same applies to the check valve CV3.

Next, the rear wheel side hydraulic system will be described.
The tenth valve device EV10 is arranged in parallel with the third valve device EV3.
And a proportional pressure reducing valve PV are connected. Tenth valve device E
V10 is a 3-port 2-position electromagnetic switching valve, which is in the first position shown in FIG. 2 in a non-actuated state, and directly connects the seventh valve device EV7 and the regulator RG to establish a proportional pressure reducing valve PV and a third valve. The communication with the regulator RG via the device EV3 is cut off. When the tenth valve device EV10 is switched to the operating second position, the seventh valve device EV7 is disconnected from the direct communication with the regulator RG, and is connected to the third valve device EV3 via the proportional pressure reducing valve PV. Third valve device EV3
It is connected to the accumulator ACC or the regulator RG depending on the operation / non-operation of the.

The proportional pressure reducing valve PV is a regulator RG.
Is supplied to the wheel cylinders Wrl, Wrr of the rear wheels via the third valve device EV3 and the tenth valve device EV10, the hydraulic pressure on the output side (the hydraulic pressure on the tenth valve device EV10 side) is The hydraulic pressure on the output side is made equal to the hydraulic pressure on the input side (the hydraulic pressure on the third valve device EV3 side) until the hydraulic pressure on the output side rises to a predetermined hydraulic pressure. The rate of increase in pressure is adjusted so as to be kept small at a predetermined rate with respect to the increase in hydraulic pressure on the input side, which is generally known as a proportioning valve. Instead of this, a liquid pressure limiting valve may be used. this is,
The hydraulic pressure on the output side is made to match the hydraulic pressure on the input side until the hydraulic pressure on the output side rises to a predetermined hydraulic pressure, but the hydraulic pressure on the output side does not rise even if the hydraulic pressure on the input side further increases. Is something
It is generally known as a limiting valve.

The seventh valve device EV7 is a 3-port / 2-position electromagnetic switching valve and has the same relationship as the fourth valve device EV4 of the front wheel side hydraulic system. That is, the first position in the non-actuated first position
0 valve device EV10, 8th valve device EV8 and 9th valve device E
V8 is communicated with, and the communication is cut off in the second position in the operating state, and the eighth valve device EV8 and the ninth valve device EV9 are switched so as to communicate with the low pressure reservoir RS.
The eighth valve device EV8 and the ninth valve device EV9 also include the fifth valve device EV8.
Similar to the valve device EV5 and the sixth valve device EV6, it is a 2-port 2-position electromagnetic on-off valve, which is in the valve open position in the non-operating state, and in the valve operating position the valve is closed and the hydraulic passage is shut off.

Further, the seventh valve device EV7 and the eighth valve device E
The check valve CV4 and the throttle passage OR3 are connected in parallel with V8, and the seventh valve device EV7 and the ninth valve device E are connected.
The check valve CV5 and the throttle passage OR4 are connected in parallel to V9, the inflow side of the check valve CV4 is connected to the wheel cylinder Wrl, and the inflow side of the check valve CV5 is connected to the wheel cylinder Wrr. The throttle passage OR3 (or the throttle passage OR4) is the first when the brake pedal BP is operated.
When the seventh valve device EV7 and the eighth valve device EV8 (or the seventh valve device EV7 and the ninth valve device EV9) are activated while the zero valve device EV10 is in the inoperative state, the regulator R
There is also one provided so that the brake fluid from G gently flows into the wheel cylinder Wrl (or the wheel cylinder Wrr). Further, the check valves CV4 and CV5 are provided for quickly causing the brake fluid pressures of the wheel cylinders Wrl, Wrr to follow the decrease in the output fluid pressure of the regulator RG when the brake pedal BP is released. Thus, the flow of the brake fluid in the direction of the tenth valve device EV10 is allowed and the flow in the reverse direction is blocked.

In the braking control device having the above structure,
The main operation according to the control by the first valve device EV1 to the tenth valve device EV10 will be described. At the time of normal brake operation, all of the first valve device EV1 to the tenth valve device EV10 described above are in the inoperative state. The first position shown in FIG. 2 is obtained. Then, in response to the operation of the brake pedal BP, the wheel cylinder Wfl or W is transmitted from the master cylinder MC via the first valve device EV1 or the second valve device EV2.
The brake fluid pressure is supplied to fr and the regulator fluid pressure is output from the regulator RG in proportion to the output of the master cylinder MC, and the tenth valve device EV10, the seventh valve device EV7, and the eighth valve device EV8 or the ninth valve device EV8. Valve device E
It is supplied to the wheel cylinder Wrl or Wrr via V9. Then, when the tenth valve device EV10 is switched and controlled to the second position, the output of the regulator RG is reduced in pressure at a predetermined rate via the proportional pressure reducing valve PV and supplied to the wheel cylinders Wrl, Wrr.

In the braking force distribution control for the front and rear wheels, when the brake pedal BP is operated, the seventh valve device EV7 is activated, and the eighth valve device EV8 and the eighth valve device EV8 are operated in accordance with the behaviors of the wheels RL, RR on the both rear sides of the vehicle. The 9-valve device EV9 is controlled to open and close,
The hydraulic pressure in the wheel cylinders Wrl, Wrr is lower than the output hydraulic pressure of the regulator RG, and the braking force on the rear wheel side is adjusted to have a predetermined relationship with the braking force on the front wheel side,
The characteristics are controlled so as to approximate the ideal braking force distribution curve. According to the present embodiment, including the braking force distribution control, various controls such as anti-skid control can be performed as described below.
As the control input, signals from the brake switch BS, the wheel speed sensors WS1 to WS4, the lateral acceleration sensor YS (or the yaw rate sensor), etc. are supplied.

If any of the wheels tends to lock during braking, the control shifts to anti-skid (ABS) control.
For example, when anti-skid control is performed on the front wheel FL, the first valve device EV1 and the fourth valve device EV4 are activated while the third valve device EV3 remains inactive, and the wheel FL The fifth valve device EV5 is opened and closed according to the locked state. As a result, the wheel cylinder Wfl is disconnected from the master cylinder MC, and instead communicates with the regulator RG. At this time, if the fifth valve device EV5 is open, the wheel cylinder Wf
The brake fluid in l is the first valve device EV1 and the fifth valve device EV
The fluid pressure in the wheel cylinder Wfl is reduced by flowing out to the low pressure reservoir RS via the fifth valve device EV4.
At this time, the sixth valve device EV6 is activated to prevent the brake fluid from the regulator RG from being wasted. On the other hand, when the fifth valve device EV5 is closed, the output hydraulic pressure of the regulator RG is the third valve device EV3 and the throttle passage OR1.
Then, through the first valve device EV1, the wheel cylinder Wf
The hydraulic pressure in the wheel cylinder Wfl is gradually increased (slow pressure increase operation). In this way, the pressure reducing operation and the gradual pressure increasing operation are repeated, and an appropriate braking force is applied while preventing the wheels FL from being locked. When a larger amount of brake fluid is required to compensate for the decrease in brake fluid due to the depressurization operation at this time, the fifth valve device EV5 is opened and brought into a rapid pressure increase operation state. It should be noted that the wheel FR side is similarly processed. Further, when anti-skid control is performed on both sides of the wheels FL and FR, when one wheel, for example, the wheel FL side is depressurized, the other wheel FR is
Since it is not possible to increase the pressure on the side, the pressure increase request on the side of the wheel FR is dealt with by the moderate increase operation.

When anti-skid control is performed on the rear wheel RL, the seventh valve device EV7 is activated while the third valve device EV3 and the tenth valve device EV10 remain inoperative. , The seventh valve device EV7 is the tenth
The communication with the valve device EV10 is cut off and the low pressure reservoir RS
Communicate with. In this state, when the eighth valve device EV8 is in the open state, the brake fluid in the wheel cylinder Wrl flows out to the low pressure reservoir RS via the eighth valve device EV8 and the seventh valve device EV7, and the pressure is reduced. At this time, the ninth valve device E
V9 is activated so that the brake fluid from the regulator RG is not wasted. On the other hand, when the eighth valve device EV8 is closed, the regulator RG
Output hydraulic pressure of the tenth valve device EV10 and the throttle passage OR3
Is supplied to the wheel cylinder Wrl via the, and the pressure is gradually increased. When a larger amount of brake fluid is required to compensate for the decrease in brake fluid due to the depressurization operation at this time, the eighth valve device EV8 is opened and brought into a rapid pressure increase operation state. Note that the same processing is performed on the wheel RR side. Further, when anti-skid control is performed on both sides of the wheels RL, RR, when one wheel, for example, the wheel RL side is depressurized, the other wheel RR side cannot be boosted. Slow pressure boosting is used to meet the demand. In this way, the slow pressure increasing operation and the pressure reducing operation are repeated according to the opening / closing control of the eighth valve device EV8 (or the ninth valve device EV9).

Next, for example, so-called traction control is performed in order to prevent the wheels RL and RR on the drive wheel side from slipping due to acceleration slip when the vehicle starts moving. As a part of this, so-called traction control is performed. Acceleration slip is prevented by applying power. During this traction control, the third valve device EV3 and the tenth valve device EV10
Is activated and, for example, when the pressure is gradually increased, the eighth valve device E
When V8 is closed, the output power hydraulic pressure of the accumulator ACC is supplied to the wheel cylinder Wrl via the third valve device EV3, the proportional pressure reducing valve PV, the tenth valve device EV10 and the throttle passage OR3, and also increases rapidly. In the case of pressure, the eighth valve device EV8 is opened and braking force is applied to the wheels RL. Conversely, when the seventh valve device EV7 is activated and the eighth valve device EV8 is opened, the wheel cylinder Wrl communicates with the low-pressure reservoir RS via the activated seventh valve device EV7. , Wheel cylinder W
The brake fluid in rl flows out and the pressure is reduced. Thus, an appropriate braking force is applied to the wheels RL according to the opening / closing control of the eighth valve device EV8. The wheels RR are also controlled in the same manner. Further, when the automatic pressurization is performed in the brake steering control, the third valve device EV3 is activated on the front wheel side and the third valve device EV3 and the tenth valve device EV on the rear wheel side.
After 10 is activated, the pressure reducing operation and the gradual pressure increasing operation are performed as in the case of the above-described anti-skid control.

The first valve device EV1 to the tenth valve device E
V10 is connected to the electronic control unit ECU shown in FIG. 3 to control the operation and non-operation of each. The electric motor (not shown) that drives the hydraulic pump HP is also an electronic control unit ECU.
And is driven and controlled by this. Also, the wheel F
Wheel speed sensors WS1 to W are provided for L, FR, RL, and RR.
S4 is provided, these are connected to the electronic control unit ECU, and the pulse signals of the number of pulses proportional to the rotation speed of each wheel, that is, the wheel speed are input to the electronic control unit ECU. . Further, a brake switch BS that is turned on when the brake pedal BP is depressed, a lateral acceleration sensor YS that detects a lateral acceleration of the vehicle, and the like are connected to the electronic control unit ECU.

As shown in FIG. 3, the electronic control unit ECU includes a microcomputer CMP including a processing unit CPU, a memory ROM, a RAM, a timer TMR, an input port IPT and an output port OPT which are interconnected via a bus. I have it. Wheel speed sensor W
The output signals of S1 to WS4, the brake switch BS, the lateral acceleration sensor YS, etc. are input to the processing unit CPU from the input port IPT via the amplifier circuit AMP, respectively. Further, from the output port OPT, the first valve device EV1 through the first valve device EV1 are connected via the drive circuit ACT.
A control signal is output to the zero valve device EV10. In the microcomputer CMP, the memory ROM stores the program corresponding to the flowcharts shown in FIG. 4 and subsequent figures, the processing unit CPU executes the program while the ignition switch (not shown) is closed, and the memory RAM stores the program. Temporarily stores variable data required for execution of.

In this embodiment constructed as described above, a series of processing such as anti-skid control is performed by the electronic control unit 10 and when the ignition switch (not shown) is closed, as shown in FIGS. Execution of the program corresponding to the flowchart of 5 starts. First, in FIG. 4 showing the main routine, in step 101, the microcomputer 11 is initialized and various calculated values are cleared. Next, at step 102, the wheel speed sensor W
The detection signals of S1 to WS4 are read and the detection signals of the lateral acceleration sensor YS are read, and based on these signals, in step 103, the wheel speed Vw of the four wheels is read.
FR, VwFL, VwRR, VwRL (These are Vw **
Is expressed).

In step 104, the normalized estimated vehicle body speed NVso ** is calculated based on the wheel speed, and the slip ratio S ** is calculated (** indicates each wheel FL,
Indicates either FR, RL, or RR. Below, the same). The normalized estimated vehicle body speed NVso ** is increased, for example, after the outputs of the wheel speed sensors WS1 to WS4 are corrected (forward / backward correction and left / right correction) according to the comparison result of comparing the tire diameters of the wheels in the front / rear and left / right directions. The estimated vehicle speed Vso ** is calculated in the same manner as in the conventional anti-skid control using the rate limit α _UP and the decrease rate limit α _DN, and the correction coefficient Δ for turning correction is calculated from this value.
Vr ** is subtracted. That is, NVso ** = Vso
It is calculated as **-ΔVr **. The correction coefficient ΔVr **
Is set based on the turning radius Rd of the vehicle and γ · VsoFW (≈Gy) according to a map (not shown) for each wheel other than the reference wheel. The slip rate SR * is SR * =
It is calculated as (NVsoF * -NVsoR * -VDCR *) / NVsoF *. VDCR * represents the bias speed.

Next, the routine proceeds to step 200, where it is judged whether or not the anti-skid control start condition is satisfied. If the start condition is satisfied and it is judged that the anti-skid control is started, the anti-skid control is executed at step 300. Transition. When it is determined in step 200 that the anti-skid control start condition is not satisfied, step 400
Then, it is determined whether or not the conditions for starting the braking steering control are satisfied, and if so, the braking steering control is performed in step 500, and if not, the processing proceeds to step 600. In step 600, it is determined whether or not the front / rear braking force distribution control start condition is satisfied. If the start condition is satisfied, the process proceeds to step 700, and the front / rear braking force distribution control is performed. If not, the process proceeds to step 800. It is determined whether or not the advanced traction control start condition is satisfied. If this start condition is satisfied, traction control is performed in step 900, and if not satisfied, step 102
Return to. Then, when the above respective controls are completed, step 1
Return to 02.

The front-rear braking force distribution control of step 700 is made up of the routine shown in FIG. 5, and the rear wheels R * (R
Regarding L, RR), servo control is performed with the slip ratio SR * o as the target value. First, in step 701, the target slip ratio SR * o is set. The target slip ratio SR * o is set based on the vehicle side slip angle β and the side slip angular velocity dβ / dt which is a differential value thereof according to a map Mpt in FIG. 8 as described later. Next, step 702.
At, the slip ratio deviation ΔSR * (= SR * o-SR *), which is the difference between the target slip ratio SR * o and the slip ratio SR * of the wheel R * obtained in step 104, is calculated, and
Front-rear vehicle body acceleration deviation ΔDVsoR * (= DVsoF * -DV
soR *) is calculated.

Then, in step 703, the control depth D for setting the starting condition of the braking force distribution control is calculated. Subsequently, in step 704, it is calculated whether or not the control depth D is equal to or larger than the start reference value Ds. If it is equal to or larger than the start reference value Ds, the process proceeds to step 705. The control depth D is obtained from the control map Mpc in FIG. 6 as described later.

In step 705, the control mode (R *) for each valve device of the wheel R * is set according to the control map Mpc of FIG. 6 based on the slip ratio deviation ΔSR * and the longitudinal vehicle acceleration deviation ΔDVsoR *. ,
The control cycle TbR * is set. That is, the slip ratio deviation Δ
The control map Mpc shown in FIG. 6 is configured with SR * as the so-called P term and the front-rear vehicle body acceleration deviation ΔDVsoR * as the D term, and the control mode is determined in accordance with this control map Mpc.
Further, as shown in FIG. 6, the I term is added to the slip rate deviation ΔSR * of the P term. That is, the slip ratio deviation ΔS
R * is supplied to the integration unit INT via the dead zone applying unit DNT, integrated there, and then added to the slip ratio deviation ΔSR * via the limiter LMT.
The dead zone applying unit DNT sets 0 when the absolute value of the slip ratio deviation ΔSR * is less than or equal to a predetermined value, and the limiter LM.
T is for limiting the output of the integrator INT to be added within a range of a predetermined upper limit value or more and a predetermined lower limit value or more. The term I is cleared if the absolute value of the slip ratio deviation ΔSR * is less than or equal to a predetermined value.

In the control map Mpc of FIG. 6, the horizontal axis represents the slip ratio deviation ΔSR * and the vertical axis represents the longitudinal vehicle body acceleration deviation Δ.
DVsoR *, which is divided into two regions (+) and (-) by an inclined line segment and a line segment parallel to the X axis. For example, the region (+) is set to the slowly increasing pressure mode, the region (-) is set to the depressurizing mode, and the control cycle TbR * is set in both regions.
The control cycle TbR * is, for example, when the length of a perpendicular line from an arbitrary point on the control map Mpc to the inclined line segment is D,
It is calculated as (TbR * = Kb−Kc · | D |) (where Kb and Kc are constants). Thus, pressure reduction or pressure increase is performed based on this control signal. Regarding the control mode, only the pressure reducing mode, the slow pressure increasing mode and the normal pressure increasing mode are used here. However, by performing the intermittent control and the duty control of each valve device in FIG. 2, it is possible to further set the gentle pressure reducing mode and the holding mode. You can

On the other hand, when it is determined in step 704 of FIG. 5 that the control depth D is less than the start reference value Ds, the process proceeds to step 706, where it is determined whether or not control is in progress.
If control is in progress, it is determined in step 707 whether or not the end reference value De (however, De <Ds) is less than the end reference value D.
If it is e or more, the routine proceeds to step 705 and the control is continued. If it is determined in step 706 that control is not being performed, the process directly returns to the main routine, and if it is determined in step 707 that the control depth D is less than the end reference value De, step 70
After the braking force distribution control is completed at 8, the process returns to the main routine.

The target slip ratio SR * o set in step 701 is based on the vehicle body side slip angle β and the vehicle body side slip angular velocity dβ / dt, and is based on the map Mpt shown in FIG.
Is set according to. That is, the vehicle body side slip angle β on the horizontal axis,
The target slip ratio SR * o is set on the vertical axis, and the zero point SRo is set.
Slopes β1 (+) and β1 (-) centered around (= 1) and dead zone D
Z1 (+) and DZ1 (-) are formed. On the other hand, based on the side slip angular velocity dβ / dt, which is the differential value of the vehicle side slip angle β, the slope (that is, the gain) β1 (+) of the region (+) and the slope β1 (-) of the region (-) according to the map Mpg of FIG. Are set respectively, and the area is set according to the map Mpd in FIG.
The dead zone DZ1 (+) of (+) and DZ1 (-) of the area (-) are set. The value of the bias speed VDCR * is set according to the map Mps of FIG. 7 based on the vehicle body side slip angle β.

The above-mentioned vehicle side slip angle β represents the slip of the vehicle body with respect to the traveling direction of the vehicle as an angle.
It can be calculated and estimated as follows. That is, β = tan ⁻¹ (Vy / Vx) can be obtained based on the ratio between the vehicle speed Vx in the traveling direction and the vehicle speed Vy in the lateral direction perpendicular to the vehicle speed. Alternatively, β = ∫ (Gy / Vso−γ) dt
You can also ask. Here, Gy is a lateral acceleration that can be detected by, for example, the lateral acceleration sensor YS, but can also be calculated based on the wheel speed difference of the front wheels and the estimated vehicle speed. Further, γ is a yaw rate, which can be detected by a yaw rate sensor (not shown), but can also be calculated based on a wheel speed difference between the front wheels. Thus, the vehicle side slip angle β can be calculated based on the lateral acceleration Gy, the estimated vehicle speed Vso, and the yaw rate γ. That is, the lateral acceleration Gy
The component is included, and the vehicle side slip angle β is the lateral acceleration G
Varies according to y. Although the longitudinal acceleration DVso is calculated by differentiating the estimated vehicle speed Vso in this embodiment, a separate (vehicle) longitudinal acceleration sensor may be provided and directly measured.

Thus, according to the present embodiment, for example, as shown in FIG. 9, in the state where the moment To is applied while the vehicle is turning, even if the braking force is further applied and the moment increases, the increase amount is increased. Since the moment ΔTc that counteracts the torque is given and the unnecessary moment ΔTs is canceled out, the braking force distribution control can be appropriately performed while maintaining the stable steering characteristic without largely changing the oversteer / understeer characteristic. .

[0043]

Since the present invention is configured as described above, it has the following effects. That is, in the braking force distribution control device according to the first aspect, the lateral acceleration detecting means detects the lateral force.
The vehicle side slip angle calculating means calculates the vehicle body side slip angle based on the lateral acceleration of the vehicle, and the drive means drives the hydraulic pressure control device according to the calculation result of the vehicle body side slip angle calculating means. Therefore, the braking force distribution control can be appropriately performed while maintaining the stable steering characteristic even during braking while the vehicle is turning, and the stability of the vehicle during braking can be maintained.

[0044]

According to the braking force distribution control device of the second aspect , the lateral load of the vehicle detected by the lateral acceleration detecting means is applied.
Based on the speed, the vehicle side slip angle calculation means
In addition to calculating the slip angle, the slip ratio calculating means calculates the slip ratio of the vehicle rear wheel with respect to the vehicle front wheel based on the wheel speed, and the target slip ratio setting means corrects the slip ratio based on the vehicle side slip angle. The target slip ratio is set based on this setting, and the control mode is set based on this target slip ratio.Therefore, braking force distribution control is performed while maintaining stable steering characteristics even during braking while the vehicle is turning. Can be appropriately performed, and the stability of the vehicle at the time of braking can be maintained.

[Brief description of drawings]

FIG. 1 is a block diagram showing an outline of a braking force distribution control device of the present invention.

FIG. 2 is an overall configuration diagram of an embodiment of a braking force distribution control device of the present invention.

FIG. 3 is a block diagram showing a configuration of the electronic control device of FIG.

FIG. 4 is a flowchart showing a process for braking force control in one embodiment of the present invention.

FIG. 5 is a flowchart showing a process for braking force distribution control of rear wheels in an embodiment of the present invention.

FIG. 6 is a block diagram showing a control cycle and a control mode in one embodiment of the present invention.

FIG. 7 is a block diagram showing setting of a bias speed used for slip ratio deviation calculation in an embodiment of the present invention.

FIG. 8 is a block diagram showing a slip ratio calculation process in an embodiment of the present invention.

FIG. 9 is an explanatory diagram showing a moment when the vehicle turns according to the present invention.

FIG. 10 is an explanatory view showing a moment and a vehicle side slip angle when the vehicle turns in the conventional device.

[Explanation of symbols]

BP brake pedal BS brake switch RS low pressure reservoir MC master cylinder RG regulator HP hydraulic pump, ACC accumulator AP auxiliary hydraulic pressure source EV1-EV10 valve device CV1-EV4 check valve OR1-OR4 throttle passage Pfr, Pfl control passage Wfr, Wfl, Wrr, Wrl Wheel cylinder WS1-WS4 Wheel speed sensor FR, FL, RR, RL wheels

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Jun Mihara 2-1-1 Asahi-cho, Kariya city, Aichi Prefecture Aisin Seiki Co., Ltd. (56) Reference JP-A-6-286598 (JP, A) JP-A-4 -257758 (JP, A) JP-A-7-117655 (JP, A) JP-A-64-85862 (JP, A) JP-A-6-144174 (JP, A) JP-A-5-170011 (JP, A) ) (58) Fields investigated (Int.Cl. ⁷ , DB name) B60T 8/00-8/96

Claims (2)

(57) [Claims] 1. A wheel cylinder for a front wheel mounted on a wheel in front of a vehicle to apply a braking force, a wheel cylinder for a rear wheel mounted on a wheel on a rear side of a vehicle to apply a braking force, and a brake fluid in response to an operation of a brake pedal. A brake fluid pressure generator for applying a brake fluid pressure to each of the front and rear wheel cylinders, and the brake provided between the fluid pressure generator and at least the rear wheel cylinder. A hydraulic control device that controls hydraulic pressure and detects the lateral acceleration of the vehicle
And a detection result of the lateral acceleration detecting means.
Based on the result, a vehicle body side slip angle calculating means for calculating a vehicle body side slip angle by converting a slip amount with respect to the traveling direction of the vehicle to an angle, and driving the hydraulic pressure control device in accordance with a calculation result of the vehicle body side slip angle calculating means. A braking force distribution control device, comprising: a driving unit that adjusts a braking force of a wheel behind the vehicle to a predetermined relationship with a braking force of a wheel ahead of the vehicle. 2. A wheel cylinder for a front wheel, which is mounted on a wheel in front of a vehicle to apply a braking force, a wheel cylinder for a rear wheel, which is mounted on a wheel behind a vehicle to apply a braking force, and a brake fluid in response to an operation of a brake pedal. A brake fluid pressure generator for applying a brake fluid pressure to each of the front and rear wheel cylinders, and the brake provided between the fluid pressure generator and at least the rear wheel cylinder. A hydraulic control device that controls hydraulic pressure and detects the lateral acceleration of the vehicle
And a detection result of the lateral acceleration detecting means.
Based on the result, the vehicle body side slip angle calculating means for calculating the vehicle body side slip angle by converting the amount of slip with respect to the traveling direction of the vehicle, and the wheel speed detecting means for detecting the wheel speed of each of the wheels in front of and behind the vehicle. And a slip ratio calculation means for calculating a slip ratio of the wheel behind the vehicle with respect to the wheel ahead of the vehicle based on the detection output of the wheel speed detection means, and the slip ratio calculated by the slip ratio calculated by the slip ratio calculation means. Target slip ratio setting means for correcting and setting a target slip ratio based on the calculation result of the means; control mode setting means for setting a control mode based on the target slip ratio set by the target slip ratio setting means; The hydraulic pressure control device is driven in accordance with the control mode set by the control mode setting means, and the braking force of the wheels on the rear side of the vehicle is adjusted to the front side of the vehicle. Braking force distribution control device being characterized in that a drive means for adjusting the predetermined relationship with the braking force of the wheels.