JP2622139B2 - Two-channel diagonal antilock controller - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a brake hydraulic system for braking a left front wheel and a right rear wheel, and a brake hydraulic system for braking a right front wheel and a left rear wheel. The present invention relates to an antilock control device in a brake hydraulic system called a two-channel diagonal type, a cross piping type, or an X piping type which is provided independently of each other.

[Conventional technology]

Conventionally, as an antilock control device of this type, Japanese Patent Application Laid-Open No. 60-2595, which was previously filed and published by the present applicant.
An anti-lock control device described in Japanese Patent Publication No. 57 is known. This is because, in the two-channel diagonal brake hydraulic system, the brake hydraulic pressure starts to be reduced under the condition that there is a possibility that the front and rear wheels in the same brake hydraulic system may be locked. Are provided in each brake hydraulic system.
Then, between each modulator and each rear wheel brake, the front wheel brake fluid pressure and the rear wheel brake fluid pressure are increased at the same rate until a predetermined break point fluid pressure is reached. A proportioning valve for limiting the rate of increase of the rear wheel brake fluid pressure to a small rate relative to the rate of increase of the front wheel brake fluid pressure is interposed.

[Problems to be solved by the invention]

In such a conventional anti-lock control device, the proportioning valve makes the rear wheel brake fluid pressure lower than the front wheel brake fluid pressure to secure the stability of the vehicle at the time of brake braking. We are trying to avoid locking. While such conventional devices have some degree of perfection, there is room for further improvement from another perspective.

For example, when the operation state of the conventional antilock control device on a road surface having a different friction coefficient μ between the left and right sides is observed, the following problem occurs.

Here, it is assumed that the friction coefficient μ of the left road surface is smaller than the friction coefficient μ of the right road. It is assumed that a vehicle equipped with the anti-lock control device travels on such a road surface and brakes are applied, so that the rear left wheel is likely to be locked. At this time, the right front wheel, which is in the same brake hydraulic system as the left rear wheel, is running on the right road surface having a large friction coefficient μ, and therefore there is usually no risk of locking.

In such a situation, in this conventional device, the brake fluid pressure of any of the front and rear wheels is reduced on the condition that any of the front and rear wheels in the same brake fluid pressure system may be locked.

Therefore, in the conventional device, since the braking force of the right front wheel, which does not originally tend to lock the wheels, is reduced more than necessary, there is a problem that the overall braking force of the vehicle is insufficient, and the braking distance is increased.

The present invention has been made in view of such problems,
In the channel diagonal type anti-lock control device, when the rear wheel tends to lock ahead of the front wheel on the road surface with different friction coefficient μ on the left and right, it is possible to reliably avoid wheel lock and secure sufficient braking force It is a technical task to make the braking distance as short as possible.

[Means to solve the problem]

According to the present invention, a brake hydraulic system for braking the left front wheel (FL) and the right rear wheel (RR) and a brake hydraulic system for braking the right front wheel (FR) and the left rear wheel (RL) are independent of each other. In the two-channel diagonal brake hydraulic system provided as described above, the brake hydraulic pressure is started to be reduced on the condition that there is a possibility that the front and rear wheels in the same brake hydraulic system may be locked. Modulators (M1, M2) to avoid locking are provided for each brake hydraulic system, and each modulator (M1, M2)
The front wheel brake fluid pressure and the rear wheel brake fluid pressure are increased at the same rate until a predetermined break point fluid pressure is reached between the vehicle and each rear wheel brake, and after the break point fluid pressure, the rear wheel brake fluid pressure is increased. A proportioning valve (PCV) that limits the rate of pressure increase to a small rate relative to the rate of increase of the front wheel brake fluid pressure is inserted.

Each proportioning valve (PCV) is connected to the input port 3 connected to the modulator (M1, M2).
And a cylinder portion 2 having an output port 4 connected to the rear wheel brake side, and interposed between the input port 3 and the output port 4 in the cylinder portion 2, and the rear wheel brake fluid The rate of increase of the pressure is the same as the rate of increase of the brake fluid pressure, and a control valve (V) for limiting the rate after the break point hydraulic pressure to a small rate, and a break point hydraulic pressure acting on the control valve (V). , A liquid chamber 15 provided in the middle of the urging force transmission path to the control valve portion (V) by the first spring 11, and a second spring provided in the liquid chamber 15. 1
A second folding spring 12 is provided between the folding spring 11 and the control valve portion (V) so as to be able to act on the control valve portion (V). The control valve section (V) is configured to set the break point hydraulic pressure higher as the urging force from the first break point spring 11 side and the second break point spring 12 side increases.

Further, a reservoir 18 is connected to the liquid chamber 15 via a switching valve 17, and the switching valve 17 and the modulator (M1, M2)
Is a control unit (ECU) that evaluates the locked state of each wheel
The operation is controlled by.

The spring force of the second break spring 12 is set smaller than that of the first break spring 11,
Normally, the hydraulic chamber 15 is filled with the hydraulic fluid and sealed by the switching valve 17, so that the control valve portion (V) and the first folding spring 11 are directly connected, and the rear wheel goes toward the lock ahead of the front wheel. When there is a tendency, the switching valve 17 is opened by a command from the control device (ECU) to release the hydraulic fluid in the fluid chamber 15 to the reservoir 18,
A two-channel diagonal anti-lock control device is configured so that the spring force of the second break point spring 12 is involved in setting the break point hydraulic pressure.

[Action]

Normally, the hydraulic chamber 15 is filled with the hydraulic fluid, and the switching valve 17 is closed and sealed. Thus, the first folding spring 11 is directly connected to the control valve portion (V). The break point hydraulic pressure at this time is determined by the spring force of the first break point spring 11, and is set at the point a in FIG.

When the brake pedal is depressed, hydraulic pressure is generated in the tandem type master cylinder (M / C), and the hydraulic pressure is transmitted to the front wheel brake and the rear wheel brake of each brake hydraulic system, and the brake is applied. Proportioning valve (PC
V), the rate of increase in the brake fluid pressure on the front and rear wheels is
Up to the break point hydraulic pressure a, the front and rear wheels are equal, and after the break point hydraulic pressure, the rear wheel brake hydraulic pressure increases at a small rate relative to the rate of increase of the front wheel brake hydraulic pressure.

Here, the friction coefficient μ on the left road surface is
It is assumed that a vehicle equipped with the device of the present invention is traveling on a smaller road surface. On the other hand, the control unit (ECU) monitors the possibility of locking of each wheel. When the brake is applied on such a road surface, the control unit (ECU) determines that the left rear wheel (RL) has a tendency to lock, and determines that the right front wheel (FR) of the same brake system does not have the tendency to lock. It shall be judged.

Under the condition that such a situation occurs, the exchange valve 17 is opened by a command from the control device (ECU), and the hydraulic fluid is released from the fluid chamber 15 to the reservoir 18. Thus, the second break point spring 12 acts on the control valve portion (V) instead of the first break point spring 11, and sets a new break point hydraulic pressure by the spring force. Since the spring force of the second break point spring 12 is smaller due to the spring force of the first break point spring 11, the break point hydraulic pressure is determined by the first break point spring 11 (see FIG. 4). (point a)) (point b in FIG. 4).

As a result, the increase in the hydraulic pressure on the rear wheel side, which tends to lock, is suppressed earlier than usual, so that the possibility that the rear wheel locks earlier can be avoided earlier than before.

However, it is still possible that the rear left wheel (RL) locks and there is no such case. In this case, in the device of the present invention, the modulators (M1, M2) operate on the condition that there is a possibility of wheel lock on one of the front and rear wheels in the same brake hydraulic system. RL),
Both brake fluid pressures of the right rear wheel (FR) are reduced.

On the other hand, regarding the brake hydraulic system of the front left wheel (FL) and the rear right wheel (RR), the front left wheel (FL) tends to lock ahead of the rear right wheel (RR) on the road surface. Then, the modulators (M1, M2) operate and the front left wheel (FL) and the rear right wheel (R
The hydraulic pressure of the brake hydraulic system of R) is reduced, and the locking of the front wheels is avoided.

In the above, the modulators (M1, M2) are provided with various switching valves, reservoirs, pumps, or accumulators as necessary, and by switching the switching valves, the brake fluid is released from each brake fluid pressure system to the reservoir to reduce the pressure. This is a general term for a device that pumps up from a reservoir, accumulates pressure in an accumulator as necessary, and sends it back to each brake hydraulic system.

Also, the control valve portion (V) of the proportioning valve (PCV) sets the rate of increase of the rear wheel brake fluid pressure equal to the rate of increase of the front wheel brake fluid pressure until the break point fluid pressure, and is small after the break point fluid pressure. Any form may be used as long as the ratio is limited.

Further, the control device (ECU) can use a known means such as a means based on a change in each wheel speed for the determination of the wheel lock tendency.

〔Example〕

Hereinafter, an embodiment of the present invention will be described with reference to FIGS.

The vehicle equipped with this device has a brake fluid system for braking the left front wheel (FR) and the right rear wheel (RR), and a brake fluid system for braking the right rear wheel (FR) and the left rear wheel (RL). And a pressure system independent of each other.

Each brake hydraulic system supplies brake hydraulic pressure from a tandem-type master cylinder (M / C) that independently generates hydraulic pressure for the two systems.

In addition, it operates on the condition that there is a possibility of wheel lock on one of the front and rear wheels in the same brake hydraulic system,
Modulators (M1, M2) for starting the reduction of the brake fluid pressure to avoid locking the wheels are provided for each brake fluid system. This modulator (M1, M2) has been described in the section of [Action].

A proportioning valve (PCV) is interposed between each modulator (M1, M2) and each rear wheel brake. Each proportioning valve (PCV)
Is a two-system integrated type integrally incorporated in one body 1.

Explaining the structure of this proportioning valve (PCV), a cylinder part 2 is formed in the body 1, and an input port 3 connected to the modulator (M1, M2) side is formed in an intermediate part of the cylinder part 2. An output port 4 connected to the rear wheel brake side is formed at one end of the cylinder portion 2.

In the cylinder portion 2, a valve piston 5 is slidably inserted between the input port 3 and the output port 4. The valve piston 5 is provided with a brake fluid passage 6 penetrating from the input port 3 to the output port 4. In the brake fluid passage 6, a turning point for opening and closing the brake fluid passage 6 by sliding of the valve piston 5. A valve 7 is provided. The breakpoint valve 7 is formed of a metal ball, is urged by a set spring 8 in a direction to be seated on the valve seat 9, and protrudes into the cylinder portion 2 when the valve piston 5 is located on the left side in FIG. It comes into contact with the contact rod 10 and separates from the valve seat 9 against the set spring 8.

The diameter of the valve piston 5 at one end on the output port 4 side is A1, and the diameter at the other end is A2 smaller than A1.

A control valve portion (V) is formed by the valve piston 5, break point valve 7, set spring 8, butting rod 10, and the like.

On the other end of the valve piston 5, a first folding spring 11 for urging the valve piston 5 in a direction in which the folding valve 7 opens to determine a breaking hydraulic pressure is provided. 11, a liquid chamber 15 provided in the middle of the urging force transmission path to the valve piston 5 and a first chamber provided in the liquid chamber 15.
A second break point spring 12 is provided between the 11 break point springs and the five valve pistons to repulsively urge them.

To explain these points in detail, the transmission piston 13 is provided in the cylinder portion 2 corresponding to the other end of the valve piston 5.
The first folding spring 11 engaged with the transmission piston 13 is provided in a spring chamber 14 provided on one side of the body 1. And the transmission piston
A second break point spring 12 is stretched between the valve piston 5 and the valve piston 5 to repulsively urge them.
The liquid chamber 15 is formed between the piston and the valve piston 5.

Liquid chamber 15 in each proportioning valve (PCV)
Are connected by a communication hole 16 provided in the body 1, and one of the liquid chambers 15 is connected to a reservoir 18 via an electromagnetic switching valve 17. Here, the spring force of the second folding spring 12 is set smaller by the first folding spring 11.

Then, when the switching valve 17 is closed and the hydraulic chamber 15 is filled with the hydraulic fluid, the transmission piston 13 and the valve piston 5 are directly connected, that is, the urging force of the first break point spring 11 is directly applied to the valve piston 5. To join. on the other hand,
When the hydraulic fluid is released from the liquid chamber 15 to the reservoir 18, the second break spring 12 becomes free and urges the valve piston 5 instead of the first break spring 11.

In addition to the structure of the hydraulic system, an electronic control unit (ECU) for controlling these operations is provided. This control device (ECU) evaluates and monitors the possibility of wheel lock, and controls the operation of the modulators (M1, M2) and the switching valve 17 based on the monitoring information.

The control device (ECU) will be described with reference to the block diagram of FIG. 2. First, the control device (ECU) includes a right front wheel speed sensor (S1), a left rear wheel speed sensor (S2), a left front wheel speed. Four arithmetic circuits (21, 22, 23, 24) for calculating wheel speeds based on signals from the sensor (S3) and the right rear wheel speed sensor (S4) are provided for each wheel.

Further, a pseudo vehicle speed calculation circuit 25 is provided for calculating the pseudo vehicle speed by comparing the wheel speed data from the four calculation circuits (21, 22, 23, 24).

On the other hand, a first low select circuit 26 is electrically connected to the right front wheel speed calculation circuit 21 and the right rear wheel speed calculation circuit 22, and a left front wheel speed calculation circuit 23 and a right rear wheel speed calculation circuit 24 are provided.
Is electrically connected to a second row select circuit 27. These low select circuits (26, 27) select and output the slower one of the front wheel speed and the rear wheel speed.

A first control logic circuit 28 and a second control logic circuit 29 are respectively connected to a stage subsequent to each row select circuit (26, 27), and the pseudo vehicle body speed is connected to each control logic circuit (28, 29). An output signal from the arithmetic circuit 25 is also input. In each of the control logic circuits (28, 29), the speed of the front wheel or the rear wheel selected by each of the low select circuits (26, 27) is compared with the pseudo vehicle speed to determine whether or not there is a possibility of wheel lock. Is done. Then, based on the result of the judgment, the modulator (M1, M2) is instructed to reduce the brake fluid pressure,
Alternatively, a re-pressurizing command is issued.

Separately from this, a first rear wheel front lock determination unit 30 is electrically connected to the right front wheel speed calculation circuit 21 and the left rear wheel speed calculation circuit 22, and a left front wheel speed calculation circuit 23 is provided. The right rear wheel speed calculation circuit 24 is electrically connected to a second rear wheel advance lock determination unit 31, and these rear wheel advance lock determination units (30, 31) are also electrically connected to the brake switch 32. Have been.

These rear wheel lead lock determination units (30, 31) compare the front wheel speed with the rear wheel speed based on the signal from the brake switch 32, assuming that the brake is applied, and compare the rear wheel speed with the front wheel speed. Then, when the predetermined speed becomes slower, it is determined that there is a tendency of the rear wheel preceding lock. The signal from each rear wheel preceding lock determining unit (30, 31) is input to the OR circuit 33. OR
A third control logic circuit 34 is connected to a stage subsequent to the circuit 33, and the switching valve 17 is connected to the third control logic circuit 34 so as to be opened and closed.

Then, the first and second rear wheel leading lock determination units (30, 3
1) The signal indicating that there is a tendency to lock the rear wheel ahead from either of the above is O
When input to the R circuit 33, the third control logic circuit 34 switches the switching valve 17
Is to be issued.

 Next, an operation example of the device of this embodiment will be described.

Normally, the liquid chamber 15 of the proportioning valve (PCV)
Is filled with hydraulic fluid and the switching valve 17 is closed, so that the second break point spring 12 is connected to the valve piston 5 and the transmission piston.
13, the valve piston 5 and the transmission piston 13 are integrated with each other, and the valve piston 5 and the transmission piston 13 and the first folding spring 11
Are directly connected to each other, so that the second break spring 12 is not involved in determining the break hydraulic pressure. In the initial state, the valve piston 5 is located at the left end of the figure as shown in FIG.

First, the normal brake braking will be described. The hydraulic pressure generated by the master cylinder is transmitted directly to the front wheels and to the rear wheels via a proportioning valve (PCV).

Here, the balance formula of the force initially applied to the valve piston 5 in the proportioning valve (PCV) is as follows.

Pm · A2 ≦ F1 (1) Pm: master cylinder fluid pressure (= front and rear wheel brake fluid pressure) F1: force of first break point spring 11 And fluid pressure when Pm · A2 = F1 ( F1 / A2) is the break point hydraulic pressure. When Pm rises above the break point hydraulic pressure, the balance equation of the force applied to the valve piston 5 is Pr · Al = Pm (A1−A2) + F1 (2) Pr: Wheel brake fluid pressure. In this case, the force of the second break spring 12 does not act on the valve piston 5.

Thereafter, the following equation obtained by transforming equation (2) is obtained as follows: Pr = Pm (A1-A2) / A1 + (F1 / A1) (3) Pm at this time = master cylinder fluid pressure = front wheel brake fluid As is apparent from the pressure, the break valve 7 repeatedly opens and closes due to the small reciprocating movement of the valve piston 5, and Pr becomes tanθ = (A1−A2) / A1 (4) with respect to Pm. To rise.

Therefore, after the turning point hydraulic pressure (point a in FIG. 4), the braking pressure of the front wheels is suppressed to be lower than the braking pressure of the front wheels, and the running stability of the vehicle during braking is ensured.

The above is the normal operation.Next, when a vehicle equipped with this device passes on a road surface with a different friction coefficient μ on the left and right, what kind of operation this device performs to avoid wheel lock 3 will be described with reference to the flowchart of FIG.

Here, it is assumed that the friction coefficient μ on the left road surface is smaller than the friction coefficient μ on the right road surface.

It is assumed that four arithmetic circuits (21, 22) receive signals from the right front wheel speed sensor (S1), the left rear wheel speed sensor (S2), the left front wheel speed sensor (S3), and the right rear wheel speed sensor (S4). , 2
3, 24) calculates each wheel speed, and further receives the respective wheel speed data from the four calculation circuits (21, 22, 23, 24), and the pseudo vehicle speed calculation circuit 25 calculates the pseudo vehicle speed. ing.

It is determined from the signal from the brake switch 32 whether or not the brake is applied (step 10). If the brake is not applied, the switching valve 17 is kept closed (step 104). Upon knowing that the brake has been applied by the signal from the brake switch 32, the first rear-wheel-leading-lock determining unit 30 calculates the calculation results from the calculation circuit 21 for the right front wheel speed and the calculation circuit 22 for the left rear wheel speed. Compare the left rear wheel (R
It is determined whether or not L) tends to lock ahead of the right front wheel (FR) (step 102).

Similarly, the second rear wheel preceding lock determination unit 31 also compares the calculation results from the left front wheel speed calculation circuit 23 and the right rear wheel speed calculation circuit 24, and determines that the right rear wheel (RR) is the left front wheel (FL). It is determined whether there is a tendency to lock earlier.

Here, because of the road surface conditions described above,
Left rear wheel-front and rear wheel system tends to lock the rear wheel ahead,
In the right rear wheel-left front wheel system, it is determined that there is no tendency for rear wheel leading lock.

Then, the output of the OR circuit 33 is turned ON, and in response to this, the third control logic circuit 34 opens the switching valve 17 (step 103),
Hydraulic fluid is released to the reservoir 18 from the fluid chambers 15 of the proportioning valves (PCV) of both systems.

Therefore, the turning point hydraulic pressure of the proportioning valve (PCV) is determined by the second turning point spring 12 this time. That is, the above equation (3) is Pr = Pm (A1-A2) / A1 + (F2 / A1) (5) F2: The force of the second break point spring 12, where F2 <F1, Break point hydraulic pressure (F2 / A1)
Is naturally smaller than the above (F1 / A1).
The break point hydraulic pressure is lower than in the previous case (point b in FIG. 4).

As a result, the increase in the hydraulic pressure on the left rear wheel side, which tends to lock, is suppressed earlier than usual, so that the possibility that the rear wheel locks in advance is avoided beforehand.

In this embodiment, each proportioning valve (PC
Since the respective liquid chambers 15 of V) communicate with each other through the communication holes 16, the turning point hydraulic pressure on the right rear wheel (RR) side, where there is no tendency to lock, is also reduced, and is adjusted to the left rear wheel (RL) Although the fluid pressure rises, each fluid chamber 15 is made independent, and a switching valve 17
And the reservoir 18 are connected, and the OR logic circuit 33 is not provided, and a control logic circuit for controlling the opening and closing of each switching valve 17 is connected to the first rear wheel advance lock determination unit 30 and the second rear wheel advance lock determination unit 31 respectively. You may make it. In this way, in the above situation, the turning point hydraulic pressure is reduced in the left rear wheel-right front wheel system that tends to lock the rear wheel ahead, but the right rear wheel that does not tend to lock the rear wheel ahead. -In the left front wheel system, since the original turning point hydraulic pressure is maintained, the braking distance of the rear wheels can be shortened without reducing the braking force of the rear wheels.

As described above, when the rear wheel is in the leading lock state, the breaking point hydraulic pressure of the proportioning valve (PCV) is reduced to prevent the rear wheel from being locked, but it is necessary to avoid the rear wheel lock depending on the situation. Not necessarily. Therefore, the antilock control after the break point hydraulic pressure drops will be described.
Here, only the left rear wheel-right front wheel system will be described.

First, even after the turning point hydraulic pressure drops, the first low select circuit 26 operates in response to signals from the right front wheel speed calculating circuit 21 and the left rear wheel speed calculating circuit 22 to operate the right front wheel (FR). And the lower one of the speeds of the left rear wheel (RL) (here, the left rear wheel speed) is selected and output. Each output from the first low select circuit 26 and the pseudo vehicle speed calculation circuit 25 is received by the first control logic circuit 28. The first control logic circuit 28 performs a comparison operation between the two to reduce the possibility of locking of the left rear wheel (RL). judge. When there is a possibility of locking, the modulator (M1) of the right front wheel-left rear wheel system operates to reduce the brake fluid pressure and avoid locking of the left rear wheel (RL).

Next, separately from the above, an operation in a case where the front wheel goes to the lock before the rear wheel will be described.

In such a case, each row select circuit (30, 31),
The risk of locking is determined by the first and second control logic circuits (28, 29), and pressure reduction / re-pressurization by the modulators (M1, M2) is repeated independently in each brake hydraulic system.

〔The invention's effect〕

According to the present invention, when the rear wheel is likely to lock earlier than the front wheel, the break point hydraulic pressure of the proportioning valve is reduced. A preceding lock can be avoided.

Therefore, when there is a possibility of the rear wheel leading lock, there is almost no chance that the brake fluid pressure of the front wheels is reduced more than necessary, so that the overall braking force can be increased as much as possible and the braking distance can be shortened accordingly.

[Brief description of the drawings]

FIG. 1 is a hydraulic diagram showing one embodiment of the present invention, FIG. 2 is a block diagram mainly showing a control device thereof, FIG. 3 is a flowchart showing an operation example of a characteristic portion of the present invention, FIG. The figure is a graph showing the state of the hydraulic pressure control (change in the break point hydraulic pressure) according to the present invention. (FL): Left front wheel, (RR): Right rear wheel, (FR): Right front wheel, (RL): Left rear wheel, (M1, M2): Modulator,
(PCV) Proportioning valve, (V) Control valve (valve piston 5, break valve 7, set spring 8, butting rod 10), (ECU) control device, 2
... Cylinder part, 3 ... Input port, 4 ... Output port, 11 ... First break point spring 11, 15 ... Liquid chamber, 12 ...
2nd break point spring, 17 ... switching valve, 18 ... reservoir.

Claims (1)

(57) [Claims] A brake hydraulic system for braking a front left wheel (FL) and a rear right wheel (RR) and a brake hydraulic system for braking a front right wheel (FR) and a rear left wheel (RL) are mutually connected. In the independently provided two-channel diagonal brake hydraulic system, the brake hydraulic pressure is reduced by starting the reduction of the brake hydraulic pressure on condition that one of the front and rear wheels in the same brake hydraulic system may be locked. Modulators (M1, M2) to avoid locking of each are installed in each brake hydraulic system, and each modulator (M1, M2)
The front wheel brake fluid pressure and the rear wheel brake fluid pressure are increased at the same rate until a predetermined break point fluid pressure is reached between the vehicle and each rear wheel brake, and after the break point fluid pressure, the rear wheel brake fluid pressure is increased. The proportioning valves (PCV) that limit the rate of pressure increase to a small percentage relative to the rate of increase in the front wheel brake fluid pressure are inserted, and each proportioning valve (PC
V) is an input port 3 connected to the modulator (M1, M2) side and an output port 4 connected to the rear wheel brake side.
And a rising rate of the rear wheel brake fluid pressure which is interposed between the input port 3 and the output port 4 within the cylinder section 2 and has a break point hydraulic pressure. A control valve section (V) for limiting the rate to a small rate after the break point hydraulic pressure, a first break point spring 11 acting on the control valve section (V) to determine the break point hydraulic pressure, A liquid chamber 15 provided in the middle of the urging force transmission path to the control valve section (V) by the first break point spring 11, and the first break point spring 11 side provided in the liquid chamber 15 and the control valve section (V ) And a second break point spring 12 provided so as to act on the control valve section (V), and the control valve section (V) is connected to the first break point spring 11 side and Second break point spring
As the urging force from the side 12 increases, the break point hydraulic pressure is set higher, and further, the liquid chamber 15 is connected to the reservoir 18 via the switching valve 17.
Are connected, and the switching valve 17 and the modulator (M1, M1
2) is a control device (EC
U), the spring force of the second break spring 12 is set to be smaller than that of the first break spring 11, and the liquid chamber 15 is normally filled with hydraulic fluid and the switching valve When the control valve (V) is sealed in at 17 and the control valve portion (V) and the first break point spring 11 are directly connected to each other, and the rear wheel tends to lock before the front wheel, the control device (ECU)
The switching valve 17 is opened by a command from the controller to release the hydraulic fluid in the liquid chamber 15 to the reservoir 18, and the spring force of the second break point spring 12 is involved in setting the break point hydraulic pressure. Two-channel diagonal antilock controller.