JP2679414B2 - Vehicle braking force left / right 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 device for controlling the lateral distribution of braking force during turning of a vehicle so that the turning locus becomes appropriate.

[0002]

2. Description of the Related Art A hydraulic brake system for a vehicle brakes each wheel by operating a wheel cylinder of each wheel with hydraulic pressure from a master cylinder in accordance with a brake pedal depression force. By the way, at the time of this braking, the front wheel load increases and the rear wheel load decreases due to the movement of the vehicle body.Therefore, if the front and rear wheel brake fluid pressures are the same, the rear wheels will lock before the front wheels and the oversteer tendency of the vehicle Occurs. On the contrary, when the front wheels lock before the rear wheels, at least the tendency of oversteering of the vehicle does not occur. From this point of view, in the general hydraulic brake device, the ideal front and rear wheel brake hydraulic pressure distribution in which the front and rear wheels are locked simultaneously is as shown by the dotted line in FIG. As shown by -c, the rear wheel brake hydraulic pressure system has a hydraulic control valve that limits the increase of the rear wheel brake hydraulic pressure P _R with respect to the front wheel brake hydraulic pressure P _{F in} the region above the split point b (critical hydraulic pressure P _S1 ). Has been inserted into. The characteristics a-b-c of FIG. 5 are located in the lower region of the figure than the ideal characteristics of the dotted line, and therefore the front wheels lock before the rear wheels, and the oversteering tendency of the vehicle can be avoided. .

[0003]

However, if light braking is performed while the vehicle is turning near the limit, both front and rear wheels will not be locked. Therefore, the front wheel cornering force increases due to the load movement accompanying braking, Rear wheel cornering force is reduced. Therefore, during the light braking, the vehicle tends to oversteer. By the way, during strong braking even when turning around the same limit, the front and rear wheels lock before the rear wheels because the left and right hydraulic pressure control valves control the front and rear distribution of the braking force. As a result, the vehicle follows a turning locus that bulges outward in the turning direction, and tends to understeer, contrary to light braking. An object of the present invention is to eliminate the above-mentioned problem by providing a braking force difference between the left and right sides so that a yaw moment that cancels the oversteering tendency and the understeering tendency is generated in a turning state.

[0004]

In order to prevent the oversteer tendency and to prevent the understeer tendency, the present invention distributes the front and rear wheel brake fluid pressure to the front wheel brake fluid pressure in the region above the split point. A hydraulic brake device for a vehicle, wherein hydraulic pressure control valves for lowering the hydraulic pressure are provided separately for the left and right rear wheel brake hydraulic pressure systems. Each has a configuration in which the rear wheel brake fluid pressure is lower than the front wheel brake fluid pressure, and the split points of the front and rear wheel brake fluid pressure distributions can be changed. Detecting means, braking force detecting means for detecting the strength of the vehicle braking force, and, in response to signals from these means, the front and rear wheel brake fluid pressures according to the strength of the braking force during turning braking. It is a means for changing the split point of the front and rear wheel brake fluid pressure distribution of the left and right rear wheel brake fluid pressure hydraulic control valves that can change the split point each having a minute split point, and the braking force is set during turning. When the braking is less than the specified value, the split point of the front and rear wheel brake fluid pressure distribution of the hydraulic control valve for the outer wheels in the turning direction is the hydraulic control valve for the inner wheel in the turning direction among the hydraulic control valves for the left and right rear wheel hydraulic pressure systems. Of the front and rear wheels, and on the contrary, when the braking force is stronger than the set value, the left and right rear wheels of the hydraulic control valve of the brake hydraulic system in the turning direction are The split point of the front / rear wheel brake fluid pressure distribution of the hydraulic pressure control valve related to is higher than the split point of the front / rear wheel brake fluid pressure distribution of the hydraulic pressure control valve related to the outer wheel in the turning direction. Is controlled so as,
And a split point changing means.

At this time, the turning detection means is configured to detect the turning degree, and the split point changing means is configured to increase the split point difference between the left and right hydraulic pressure control valves as the turning degree becomes stronger. Good to do.

[0006]

[Operation] When braking by the hydraulic brake device, the left and right hydraulic control valves, which are separately provided for the left and right rear wheel brake hydraulic systems, are located above the split point and the rear wheel hydraulic pressure is greater than the front wheel hydraulic pressure. The front and rear wheel brake fluid pressure distribution is controlled to be low. By the way, each of the left and right rear wheel brake fluid pressure control valves can change the split point of the front and rear wheel brake fluid pressure distribution so that the rear wheel brake fluid pressure is lower than the front wheel brake fluid pressure. Further, the split point changing means responds to the signals from the turning detection means and the braking force detection means in accordance with the strength of the braking force at the time of turning braking, and splits the front and rear wheel brake hydraulic pressure distribution. The split points of the front and rear wheel brake fluid pressure distributions of the left and right rear wheel brake fluid pressure hydraulic control valves, each of which has a respective point, can be changed as follows.

That is, during turning in which the turning detection means detects the turning state of the vehicle, during light braking in which the vehicle braking force detected by the braking force detection means is less than a set value, the split point changing means changes the left and right rear wheel brake fluid. Of the hydraulic control valves of the pressure system, the split point of the front and rear wheel brake hydraulic pressure distribution of the hydraulic control valve for the outer wheel in the turning direction is greater than the split point of the front and rear wheel brake hydraulic pressure distribution of the hydraulic control valve for the inner wheel in the turning direction. Change and control the split point to be higher. As a result, the braking force on the outside in the turning direction is made larger than the braking force on the inside in the turning direction, and a yaw moment that cancels the oversteer tendency of the vehicle that occurs as described above during light braking during turning is generated. Therefore, while the vehicle normally follows a turning locus that tends to oversteer in the turning braking state, the vehicle can be corrected and travel along the regular turning locus.

On the other hand, during turning when the turning detection means detects the turning state of the vehicle, when the vehicle braking force detected by the braking force detection means is equal to or more than the set value, the split point changing means, conversely, Among the hydraulic control valves of the rear wheel brake hydraulic system, the split point of the front and rear wheel brake hydraulic pressure distribution of the hydraulic pressure control valve for the inner wheel in the turning direction is the front and rear wheel brake hydraulic pressure distribution of the hydraulic control valve for the outer wheel in the turning direction. Change and control the split point so that it is higher than the split point. As a result, the braking force on the inner side in the turning direction is made larger than the braking force on the outer side in the turning direction, and a yaw moment is generated that cancels the understeer tendency of the vehicle that occurs during forced movement during turning as described above. Therefore, the vehicle can travel along the regular turning locus after being corrected, while following the turning locus which tends to be understeer in the turning braking state. From the above, during braking during non-turning, the front and rear wheel brake fluid pressure distribution can be controlled by the left and right fluid pressure control valves so that the rear wheel brake fluid pressure becomes lower than the front wheel brake fluid pressure in the region above the split point. It is possible to achieve its original function, and of course, even during braking during turning, the left and right hydraulic pressure control valves are used to set the split point on the outer side of the turning wheel in weak braking where the braking force is less than the set value. On the contrary, in the case of a forced motion in which the braking force is higher than the turning inner wheel side and the braking force is equal to or more than the set value, the split point on the turning inner wheel side can be raised higher than the turning outer wheel side, and even when braking in the same turning state, The problem that the steer characteristic changes depending on the strength of the braking force has been solved, and even if the steer characteristic changes according to the strength of the braking force, it is possible to appropriately cope with the change.

In this case, when the turning detection means detects the degree of turning, and the split point changing means increases the split point difference between the left and right hydraulic pressure control valves in accordance with the degree of turning, Is properly corrected in all turning states, and the turning locus of the vehicle can always be properly maintained regardless of the degree of turning.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings. 1 and 2 show an embodiment of a braking force left / right distribution control device according to the present invention, and FIG. 1 is a brake hydraulic piping diagram,
FIG. 2 is a control circuit diagram. In FIG. 1, 1 is a brake pedal, 2 is a two-system brake master cylinder that outputs hydraulic pressure according to the pedaling force, 3L and 3R are left and right front wheel cylinders, and 4L and 4R are left and right rear wheel cylinders. While the left and right front wheel cylinder 3L of the master cylinder hydraulic pressure outputted from both the outlet of the master cylinder 2, as the front wheel brake fluid pressure P _F to the 3R, also the other left and right rear wheel cylinder 4L, rear to 4R-wheel brake hydraulic pressure _They are supplied as P _RL and P _RR , respectively. Reference numeral 5 is a well-known 4-channel anti-skid control unit in which the left and right front wheel brake fluid pressures P _F are individually locked and the left and right rear wheel brake fluid pressures P _RL and P _RR are individually locked. Control to prevent.

Hydraulic pressure control valves 6L and 6R, which are well known from Japanese Patent Laid-Open No. 61-238554, are inserted in the left and right rear wheel brake hydraulic systems, respectively, as proportioning valves. Since these valves have the same configuration, only the valve 6L will be described in detail, and the corresponding portion of the valve 6R will be illustrated by the same reference numerals with a suffix of R instead of L, and redundant description will be avoided. The valve 6L controls the master cylinder hydraulic pressure input to the inlet port 7L and outputs it from the outlet port 8L, and supplies this output pressure to the wheel cylinder 4L as the rear wheel brake hydraulic pressure P _RL .
The stepped plunger 9L is elastically supported at the limit position shown by the pressure adjusting spring 10L. Insert the poppet valve body 11L into the large diameter end of the stepped plunger 9L, and insert the poppet valve body 11L into the return spring 12
Energize toward valve seat 13L with L. At the limit position of the stepped plunger 9L, the poppet valve body 11L is seated on the valve seat 13L.
And the rear wheel brake fluid pressure P _RL is made equal to the master cylinder fluid pressure, and therefore the front wheel brake fluid pressure P _F , through the ports 7L and 8L. Therefore, the front and rear wheel brake hydraulic pressure distribution initially has a characteristic ab shown in FIG. By the way, during this time, as the hydraulic pressure rises, the plunger 9L moves leftward in the figure against the pressure adjusting spring 10L, and when the critical hydraulic pressure shown by P _S1 in FIG. 5 (determined by the set load of the spring 10L) is reached, the poppet valve Body 11L is seated on valve seat 13L by return spring 12L and self-closes. At this time, port 7L,
8L is cut off, the increase in the master cylinder hydraulic pressure does not directly increase the rear wheel brake hydraulic pressure P _RL , and the increase in the rear wheel brake hydraulic pressure P _RL is limited as follows. That is,
When the poppet valve body 11L is closed, the force to the left in the figure due to the rear wheel brake fluid pressure P _{RL is} applied to the large diameter end of the plunger 9L, and the master cylinder fluid pressure (the same as the front wheel brake fluid pressure P _F is applied to the stepped portion of the plunger 9L). ), The rightward force in the figure acts on each. When the master cylinder hydraulic pressure rises by a certain value, the plunger 9L is moved rightward in the figure to set the poppet valve body 11L to the open valve position again, and the rear wheel brake hydraulic pressure P _RL is increased. Due to the increase in the rear wheel brake fluid pressure, the plunger 9L is moved to the left in the figure to move the poppet valve body 11L.
Is closed again, and the rear wheel brake hydraulic pressure is increased by a certain value that is less than the increase in the master cylinder hydraulic pressure. By repeating such an action, the rear wheel brake fluid pressure P _RL is restricted from increasing relative to the master cylinder fluid pressure (front wheel brake fluid pressure P _F ) as shown by the bc characteristic after the split point b as shown in FIG. The brake fluid pressure distribution characteristic can be approximated to the ideal characteristic shown by the dotted line. The hydraulic pressure control valve 6R also controls the corresponding right rear wheel brake hydraulic pressure P _RR in the same manner to achieve similar front and rear wheel brake hydraulic pressure distribution characteristics.

In FIG. 5, in order to allow the split point to be raised to d or lowered to f, as shown in FIG. 1, the pressure adjusting spring 10L far from the plunger 9L.
The spring seat 14L on which the end of the seat is seated abuts against the adjusting screw 16L via the ball 15L, and the set load of the pressure adjusting spring 10L can be changed by the screw 16L. Therefore, the screw 16L is rotationally engaged with the output shaft 17La of the motor 17L so as to be displaceable in the axial direction. The motors 17L and 17R are reversible motors that serve as split point changing means, and their respective drive directions and drive amounts are individually controlled by the controller 18. The pressure control spring 10L in the controller 18, the load sensor 19L for detecting the set load of 10R, and the signal from the 19R, the signal output from the lateral G sensor 20 as the turning detection means for detecting a lateral acceleration Y _G of the vehicle And a signal output from the front / rear G sensor 21 as a braking force detecting means for detecting the front / rear acceleration X _{G of the} vehicle.

The controller 18 controls the motors 17L and 17R individually based on these input information to control the left side control circuit 18L in FIG. 2 and a similar unillustrated right side control circuit (the motor 17L to the motor 17R). , Load sensor 19L load sensor
19R) (equivalent to the ones replaced with 19R). The motor 17L is connected to the battery E through the ignition switch IG, the main relay contact S1 in sequence, and the motor rotation direction switching relay contacts S2, S3. Relay contact
S1 is a normally open contact that closes when the relay coil RL1 is ON, and relay contacts S2 and S3 are switched from the solid line position to the dotted line position when the relay coil RL2 is ON to switch the rotation direction of the motor 17L by changing the energizing direction. . The relays RL1 and RL2 each have one end connected to a power supply and the other end grounded through the collector-emitter paths of the transistors T1 and T2. Transistor
The base of T1 is connected to the output of the OR gate OR1, and the two inputs of the OR gate and the base of the transistor T2 are respectively connected to the comparison circuit 31.
Connect to The comparison circuit 31 includes comparators 32 and 33 and a voltage dividing resistor R.
1, R2 and a diode D1 are provided, and the resistors R1 and R2 are connected in series with the diode sandwiched therebetween, and the resistor R2 is grounded.
The diode D1 and the resistors R1 and R2 are connected to the positive inputs of the comparators 32 and 33, respectively, and the negative inputs of the comparators 32 and 33 are connected between the voltage dividing resistors R3 and R4. The output from the load sensor 19L via the amplifier 34, that is, the pressure adjusting spring 10L, is applied to the voltage dividing resistor R3.
Apply a voltage corresponding to the set load (see Fig. 1).

The left target critical hydraulic pressure calculation circuit is used for the voltage dividing resistor R1.
A voltage corresponding to the target critical hydraulic pressure from 35 is applied, and this circuit finds the critical hydraulic pressure of the left hydraulic pressure control valve 6L to be targeted based on the information from the lateral G sensor 20 and the front and rear G sensor 21, and responds. Shall output the voltage. This voltage is the resistance R1, R2
Pressure spring required to obtain the target critical hydraulic pressure by being divided by
The voltage corresponding to the set load of 10L appears between the resistors R1 and R2. However, by installing the diode D1, the voltages V1 and V2 (V2 = V1-Vd) are applied to the positive inputs of the comparators 32 and 33, respectively, due to the difference in voltage Vd corresponding to hysteresis, and the comparator 3
It is compared with the voltage V3 corresponding to the actual set load of the pressure regulating spring 10L applied to the negative inputs of 2, 33.

The left-side target critical hydraulic pressure calculation circuit 35 calculates the left-side target from the table data corresponding to FIG. 3 based on the lateral acceleration Y _G detected by the sensor 20 or by calculating the corresponding P _SL = P _S1 + B · Y _G. Determine the critical fluid pressure P _SL . The right target critical hydraulic pressure calculation circuit in the right side control circuit (not shown) similar to that in FIG. 2 is obtained from the table data corresponding to the solid line in FIG. 3 or the corresponding calculation of P _SR = P _S1 −B · Y _G The right target critical hydraulic pressure P _SR is calculated. In Fig. 3, when the lateral acceleration Y _G is 0,
That is, during non-turning, both the left and right target critical hydraulic pressures P _SL and P _SR are not as shown by P _S1 in FIG. 5, and the front and rear wheel brake hydraulic pressure distribution characteristics are approximated to the ideal characteristics on the left and right sides, and the lateral acceleration Y During the turn in which _G occurs, the target critical hydraulic pressure of the hydraulic control valve for the outer wheel in the turning direction is proportional to the degree (P _SL during right turn,
During left turning enhance P _SR), target critical fluid pressure in the hydraulic pressure control valve according to the turning direction inside wheel in inverse proportion to the turning degree (turning right is P _SR, it is turning left to lower the P _SL) Indicates that.

By the way, the proportional constant B in FIG. 3 is the vehicle region speed X _G detected by the front and rear G sensor 21 as shown in FIG.
As a function of B = B ₀ −D · X _G , and X _G =
When 0 is not applied, the maximum positive value B _O is set, and it is inversely proportional to the increase of the deceleration X _G (proportional constant D) and gradually decreased. Therefore, the proportional constant B At light braking less than the set deceleration X _GS, X _GS
Farther from the absolute value takes a large positive value, when X _GS more forced dynamic, absolute value farther from X _GS takes a large negative value.

The solid line in FIG. 3 shows the characteristics of the left and right critical hydraulic pressures P _SL , P _SR at the time of non-braking with X _G = 0. The proportional constant B shown in FIG. When approaching and X _G = X _GS , they coincide with the dotted line in FIG. 3, and the characteristics of the left and right critical hydraulic pressures P _SL , P _SR at the time of further forced movement are P _SL1 ,
The vertical relationship is reversed as illustrated by P _SR1 . At the time of this reverse rotation, the target critical hydraulic pressure of the hydraulic control valve for the inner wheel in the turning direction (P _SR1 during the right turn and P _{SL1 for the} left turn) is the target critical pressure of the hydraulic control valve for the outer wheel in the turning direction. It becomes higher than the hydraulic pressure (P _SL1 during right turn, P _SR1 during left turn).

The operation of the above embodiment will now be described. The circuit 35 of FIG. 2 obtains the left-side target critical hydraulic pressure P _SL from the above, and sets it to P _S1 during non-turning and during light braking corresponding to the lateral acceleration Y _G during turning (as illustrated in FIG. 3). If X _G <X _GS ),
For example, if P _S2 is set, and if forcibly moving (X _G ≧ X _GS ), then for example P
Defined as _S3 . The diode D1 is sandwiched between the voltage dividing resistors R1 and R2, and the upper limit value V1 and the lower limit value V2 of the voltage corresponding to the set load of the pressure regulating spring 10L necessary to obtain the left target critical hydraulic pressure are generated on both sides of the diode D1. . The comparators 32 and 33 and the OR gate OR1 have a voltage range V3 between the voltage dividing resistors R3 and R4 within the voltage range between the upper and lower limits.
When the set load of the pressure regulating spring 10L corresponds to the left-side target critical hydraulic pressure, both transistors T1 and T2 are turned on.
Turn off. At this time, the relay contact S1 opens and the relay contact S
2, S3 is in the solid line position, the motor 17L is stopped and the set load of the pressure regulating spring 10L is kept as it is.

If V3 <V2, that is, if the set load of the pressure-adjusting spring 10L is too small for the left-side target critical hydraulic pressure P _SL (P _S2 , P _S3 ), both transistors T1 and T2 are turned on and relay contact S1 is turned on. Close and put relay contacts S2 and S3 in dotted line position. This causes the motor 17L to rotate in the normal direction, and the motor 17L
L increases the set load of the pressure regulating spring 10L, and when this becomes the one that corresponds to the target critical hydraulic pressure, the motor 17L stops as described above.

If V3> V1, that is, if the set load of the pressure regulating spring 10L is too large for the target critical hydraulic pressure, the transistor T1 is turned on, the transistor T2 is turned off, the relay contact S1 is closed, and the relay contact S2, Set S3 to the solid line position. As a result, the motor 17L is rotated in the reverse direction, the set load of the pressure regulating spring 10L is reduced, and when it reaches the target critical hydraulic pressure, the motor 17L is stopped as described above.

As for the right-side target critical hydraulic pressure P _SR , as shown in FIG. 3, the right-side target critical hydraulic pressure is determined as P _S1 during non-turning and during light turning in response to the lateral acceleration Y _G. (X
_{If G} <X _GS ), for example, P _S4 is set, and forcibly operating (X _G ≧
X _GS ) is defined as P _S5 . Then, the pressure adjusting spring 10R is adjusted by the motor 17R so that the set load of the pressure adjusting spring 10R corresponds to this right side target critical hydraulic pressure P _SR (P _S4 , P _S5 ).

By this action, the set loads of the pressure-adjusting springs 10L and 10R are adjusted so that the target critical hydraulic pressures P _SL and P _SR can be achieved. These left and right target critical hydraulic pressures P _SL and P _SR are respectively shown in FIG. As shown in, the same P _S1 is set during non-turning, and during turning, the lateral acceleration Y
_For light braking according to _G (turning degree), increase the target critical hydraulic pressure P _SL on the left side (outer turning wheel side) to P _S2 and decrease the target critical hydraulic pressure P _SR on the right side (turning inner wheel side) to P _S4 On the contrary, if it is forced motion even during the same turn, the target critical hydraulic pressure P _SR on the right side (turning inner wheel side) is increased to P _S5 , and the target critical hydraulic pressure P _SL on the left side (turning outer wheel side) is decreased to P _S3 . Let Therefore, as shown in FIG. 5, the front and rear wheel brake fluid pressure distribution characteristics are the same abc characteristics on the left and right during non-turning, and light braking (X _G
<X _GS ) Left side (turning outer wheel side) Rear wheel brake fluid pressure P
_RL is controlled so as to have a-d-e characteristics, and right side (turning inner wheel side) rear wheel brake hydraulic pressure P _RR has a-f-g characteristics. If forced motion (X _G ≧ X _GS ) even during the same turn, the rear wheel brake fluid pressure P _RR on the right side (inner wheel side of the turn) is the _ah -i characteristic, and the rear wheel brake fluid pressure P _RL on the left side (outer wheel side of the turn). Are controlled so as to have a-j-k characteristics.

As a result, during turning, the outer rear wheel, which is lightly braked, is given a larger braking force than the inner rear wheel, and if it is forced, the inner rear wheel is given a larger braking force than the outer rear wheel. Due to the power difference, the vehicle is given a yaw moment that counteracts the oversteer tendency during light braking during turning and a yaw moment that counteracts the understeer tendency during forced motion during turning, and should normally be oversteered (during light braking). ) And understeer tendency (during forced movement) while tracing the turning locus, these can be corrected and the vehicle can travel along the regular turning locus.

In this example, since the left-right critical hydraulic pressure difference (left-right braking force difference) during turning is proportional to the lateral acceleration Y _G (degree of turning), the oversteer tendency and the understeer that become higher depending on the degree of turning. Since a left-right braking force difference can be given in response to the tendency, the effect of correcting the turning locus can be reliably achieved in any turning state. In addition, the turning state is not limited to the lateral acceleration as described above, but also the yaw rate of the vehicle, the steering angle, the difference between the left and right wheel speeds,
Alternatively, it goes without saying that it can be detected from a combination thereof. Further, in this example, the longitudinal G sensor 21 that measures the longitudinal acceleration X _G is used to detect the braking strength, but instead of this, the outlet hydraulic pressure of the master cylinder 2 is detected or the pedaling force of the brake pedal 1 is detected. It goes without saying that it may be detected.

[0025]

As described above, according to the braking force left / right distribution control device of the present invention, the front / rear wheel brake fluid pressure is distributed more than the front wheel brake fluid pressure in the region above the split point. Each of the left and right rear wheel brake fluid pressure hydraulic control valves is designed so that the rear wheel brake fluid pressure is lower than the front wheel brake fluid pressure. In the case of weak braking during turning, the split points that have split points for front and rear wheel brake fluid pressure distribution can be changed. Since the split point of the pressure control valve is set higher than the split point of the inner ring side hydraulic pressure control valve, the left and right hydraulic pressure control valves described above are used for braking during non-turning braking. It is possible to control the front and rear wheel brake fluid pressure distribution so that the rear wheel brake fluid pressure becomes lower than the front wheel brake fluid pressure in the region above the lit point, and of course the original function can be exerted, as well as turning. Even during middle braking, the left and right hydraulic pressure control valves are used to provide a left and right braking force difference such that the braking force on the outer wheel side becomes larger than the braking force on the inner wheel side during weak braking during turning, and the vehicle is controlled during turning light braking. A yaw moment that cancels the oversteering tendency can be applied to the vehicle, and the turning locus can be appropriately maintained during the turning light braking of the vehicle. By thus increasing the braking force on the outer wheel side, the wheel load on this outer wheel is made heavier by the turning centrifugal force, so that the braking efficiency is improved and the braking distance can be shortened. it can. Also, if the forced motion during turning, conversely, the split point of the inner-wheel side hydraulic control valve of the left and right hydraulic pressure control valves is made higher than the split point of the outer-wheel side hydraulic control valve. A left-right braking force difference that makes the inner-wheel braking force greater than the outer-wheel braking force during forced motion is applied, and a yaw moment that cancels the understeer tendency of the vehicle during forced turning can be imparted to the vehicle. It is possible to properly maintain the turning locus during the forced turning motion. Therefore, even when braking in the same turning state, the problem as described above that the steering characteristic changes depending on the strength of the braking force is solved, and even if the steering characteristic changes according to the strength of the braking force, the steering characteristic can be properly adjusted. Can respond.
When the difference between the split points between the left and right hydraulic pressure control valves is made larger as the degree of turning becomes stronger, this difference matches oversteering tendency and understeering tendency which differ depending on the turning degree. Therefore, the turning trajectory can be corrected at all times without excess or deficiency.

[Brief description of the drawings]

FIG. 1 is a hydraulic brake piping diagram showing an embodiment of a braking force left / right distribution control device according to the present invention.

FIG. 2 is a control circuit diagram of a left hydraulic pressure control valve in FIG.

FIG. 3 is a characteristic diagram illustrating a control characteristic of a target critical hydraulic pressure.

FIG. 4 is a characteristic diagram showing a change characteristic of a control proportional constant of a target critical hydraulic pressure.

FIG. 5 is a diagram illustrating the left and right front and rear wheel brake fluid pressure distribution characteristics when the device of the present invention is used.

[Explanation of symbols]

 1 Brake pedal 2 Brake master cylinder 3L Left front wheel wheel cylinder 3R Right front wheel wheel cylinder 4L Left rear wheel wheel cylinder 4R Right rear wheel wheel cylinder 5 Anti-skid control unit 6L Left hydraulic pressure control valve 6R Right hydraulic pressure control valve 10L Pressure adjusting spring 10R Pressure adjusting spring 16L Adjusting screw 16R Adjusting screw 17L Motor (split point changing means) 17R Motor (split point changing means) 18 Controller 19L Load sensor 19R Load sensor 20 Lateral G sensor (turn detection means) 21 Front / rear G sensor (braking force) Detection means) 31 Comparison circuit 35 Left side target critical hydraulic pressure calculation circuit

Claims (2)

(57) [Claims] 1. A hydraulic control valve for controlling the distribution of front and rear brake fluid pressure in the region above the split point so that the rear brake fluid pressure is lower than the front brake fluid pressure. In the vehicle hydraulic brake device separately provided with, the respective hydraulic control valves of the left and right rear wheel brake hydraulic systems are such that the rear wheel brake hydraulic pressure is lower than the front wheel brake hydraulic pressure. The split point of the front and rear wheel brake fluid pressure distribution is changeable, and further, a turning detection means for detecting the turning state of the vehicle, a braking force detection means for detecting the strength of the vehicle braking force, and In response to a signal, the left and right rear wheel brake hydraulic system hydraulic pressure control is capable of changing the split points, each having a split point of the front and rear wheel brake hydraulic pressure distribution according to the strength of the braking force during turning braking. A means for changing the split point of the front-rear wheel brake fluid pressure distribution of the control valve, which is one of the hydraulic control valves of the left and right rear wheel brake fluid pressure system during turning when light braking with a braking force less than a set value. Direction, the split point of the front and rear wheel brake hydraulic pressure distribution of the hydraulic control valve is higher than the split point of the front and rear wheel brake hydraulic pressure distribution of the hydraulic control valve related to the turning direction, and vice versa. When the power is strongly braked above the set value, the split point of the front and rear wheel brake fluid pressure distribution of the hydraulic pressure control valve of the left and right rear wheel brake hydraulic pressure system related to the inner wheel in the turning direction is related to the outer wheel in the turning direction. A braking force left / right distribution for a vehicle, comprising: split point changing means for controlling the front / rear wheel brake fluid pressure distribution of the fluid pressure control valve to be higher than the split point. The control device. 2. The turning detection means according to claim 1 , wherein the turning detection means detects the degree of turning, and the split point changing means increases the difference in split points between the left and right hydraulic control valves as the turning degree increases. A braking force left / right distribution control device for a vehicle, characterized in that