JPH0562373U - Brake fluid pressure control device - Google Patents

Abstract

(57) [Abstract] [Purpose] Prevents swinging and rear wheel lock during braking while the vehicle is turning or is lightly loaded, and it is sufficient for the rear wheels when braking while being heavily loaded and straight ahead. Secure a proper braking force. [Structure] A master cylinder 1 that generates a brake fluid pressure in accordance with a depression amount of a brake pedal 2, and a primary passage 4 that communicates between the master cylinder 1 and a wheel cylinder 3 on a rear wheel side. In the brake fluid pressure control device provided with the proportioning valve 11 for controlling the fluid pressure in the hydraulic fluid 3 through the spring force of the compression spring 17, the variable mechanism 12 for varying the spring force of the compression spring 17 is provided.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a brake fluid pressure control device for detecting a wheel lock state and controlling a brake fluid pressure of a wheel cylinder.

[0002]

[Prior Art]

 As is well known, various braking systems for automobiles have been provided with various so-called anti-lock braking systems (ABS) that prevent the wheels from being locked during sudden braking.

As one of them, for example, there is a closed circulation type brake hydraulic pressure control device for an X pipe used for a front-wheel drive vehicle (FF), and the X pipe position of this device is at each wheel on the left and right rear wheels. A proportioning valve is provided to control the cylinder brake fluid pressure.

The outline will be described with reference to FIG. For convenience, one side of the left and right rear wheels will be described.

That is, 1 is a master cylinder that generates hydraulic pressure according to the amount of depression of the brake pedal 2, 3 is a wheel cylinder on the rear wheel side, and 4 is a primary passage that connects the master cylinder 1 and the wheel cylinder 3 to each other. The downstream passage portion 4a (on the wheel cylinder 3 side) of the primary passage 4 is in the form of an X pipe with the downstream passage portion of the secondary passage (not shown). Further, a proportioning valve 5 is provided at this X piping position.

The proportioning valve 5 controls the brake fluid pressure in the wheel cylinders 3 on the left and right rear wheels, and when the brake pedal 2 is depressed, the brake fluid from the master cylinder 1 passes through the primary passage 4. The pressure flows into the cylinder 7 through the through hole 6a of the valve body 6, but at this time, the piston 8 is located in the maximum leftward direction by the spring force of the compression spring 9, and the communication passage 8a is opened in the check valve 10. It is opened apart from. Therefore, the hydraulic pressure in the cylinder 7 is transmitted from the communication passage 8a into the wheel cylinder 3 through the through hole 8b and the downstream passage portion 4a.

Since the front end side pressure receiving surface 8c of the piston 8 is larger than the pressure receiving area of the rear end side pressure receiving surface 8d, the piston 8 gradually moves to the right against the spring force of the compression spring 9. The communication passage 8a is closed by the valve body 10a of the check valve 10. As a result, the communication between the primary passage 4 and the downstream passage portion 4a is blocked, and the inside of the wheel cylinder 3 is reduced in pressure below the wheel cylinder internal pressure on the front wheel side. This prevents the tail swing during braking while the vehicle is turning and the rear wheel lock during braking when the vehicle rear part is lightly loaded to stabilize the vehicle posture during braking. ..

[0008]

[Problems to be solved by the device]

 However, in the conventional device, the spring force of the compression spring 9 of the proportioning valve is relatively small and fixed. Therefore, as described above, the tail swing while turning the vehicle and the rear wheel lock at the time of light loading can be prevented, but when the vehicle is heavily loaded and the straight swing sudden braking is rare, the tail swing is less likely to occur. The internal pressure of the wheel wheel cylinder 3 cannot be increased sufficiently. Therefore, a sufficient braking force cannot be obtained on both rear wheel sides. As a result, the load on the braking device on the front wheel side becomes large, and a so-called fade phenomenon easily occurs.

[0009]

[Means for Solving the Problems]

 The present invention has been devised in view of the above-mentioned conventional problems, and includes a master cylinder that generates brake fluid pressure according to the amount of depression of the brake pedal, and the master cylinder and the left and right rear wheels. A hydraulic passage communicating with the wheel cylinder, and a proportioning provided downstream of the hydraulic passage for controlling the brake hydraulic pressure transmitted from the master cylinder to each wheel cylinder via the spring force of a spring member. In the brake fluid pressure control device including a valve, a variable mechanism for varying the spring force of the spring member is provided.

[0010]

[Action]

 For example, when braking during turning of the vehicle or during light loading, the spring force of the spring member is set to a relatively small value by the variable mechanism to obtain the same effect as in the conventional method, while at the time of heavy loading, sudden braking during straight running. At times, the variable mechanism increases the spring force of the spring member to slow the closing operation of the valve. Therefore, the brake fluid pressure of the master cylinder due to the depression of the brake pedal is directly transmitted from the proportioning valve to the wheel cylinder through the fluid pressure passage, so that a sufficient braking force for the rear wheels can be obtained.

[0011]

【Example】

 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

1 to 3 show an embodiment of a brake fluid pressure control device of the present invention, in which 1 is a master cylinder for generating brake fluid pressure according to the amount of depression of a brake pedal 2, 3 is one rear Wheel cylinders 4 on the wheel side are primary passages on one side, which are hydraulic passages that connect the master cylinder 1 and the wheel cylinders 3, and 11 are provided between the primary passages 4 and the downstream passage portion 4a. The proportioning valves, 12 are variable mechanisms.

The proportioning valve 11 has a substantially cylindrical valve body 13, a stepped diameter cylinder 14 formed inside the valve body 13, and an axially slidable portion inside one end of the cylinder 14. And a check valve 16 provided in the other end portion of the cylinder 14 and a piston 15 that divides the inside of the cylinder 14 into a first pressure receiving chamber 14a on the right side and a second pressure receiving chamber 14b having a large diameter on the left side. And a compression spring 17 that is a spring member that is elastically mounted on the check valve 16 side and biases the piston 15 toward the second pressure receiving chamber 14b.

The valve body 13 has a through hole 18 formed in a side wall thereof for communicating the primary passage 4 and the first pressure receiving chamber 14a along the radial direction, and a second pressure receiving chamber 14b at the center of the front end wall. A communication hole 19 that communicates with the downstream passage portion 4a is formed along the axial direction.

The piston 15 has a communication passage 20 penetrating the first pressure receiving chamber 14a and the second pressure receiving chamber 14b in the central axial direction, and the first pressure receiving chamber is formed at the rear end of the cylindrical main body 15a. 14a, a first pressure receiving surface 21 is formed, and a second pressure receiving surface 22 having a larger pressure receiving area facing the second pressure receiving chamber 14b than the first pressure receiving surface 21 is formed at the front end of the flange portion 15b provided at the front end of the main body 15a. Has been done.

The check valve 16 has a tubular portion 23 integrally formed on the inner surface of the bottom wall 13 a of the valve body 13, and a ball provided so as to be movable back and forth through a tip hole of the tubular portion 23. It is composed of a valve element 24 in the shape of a rod and a coil spring 25 that is elastically mounted in the tubular portion 23 to urge the valve element 24 to the advanced position.

The compression spring 17 is elastically mounted between the tip of a plunger 26, which will be described later, and the first pressure receiving surface 21, and biases the piston 15 to the front position (the second pressure receiving chamber 14b side) by the spring force. It has become. The compression spring 17 has a reference spring force set to be relatively small like the conventional one, and the variable mechanism 12 changes the spring force.

The variable mechanism 12 advances the plunger 26 through the plunger 26 slidably provided on the outer periphery of the cylindrical portion 23 in the cylinder 14 and the pressure chamber 27 provided in the bottom wall 13 a of the valve body 13. It is composed of a hydraulic control circuit 28 that slides in the leftward direction. The plunger 26 has a cylindrical shape, one end of the compression spring 17 is seated on the front end face, and the rear end face is a pressure receiving face facing the pressure chamber 27. The hydraulic control circuit 28 uses equipment used in a so-called traction control system (TCS) for preventing wheel slip that occurs when the vehicle is suddenly accelerated, and one end of the hydraulic control circuit 28 is provided in the pressure chamber 27. A pressure accumulator 30 provided at the other end of the connected oil passage 29, an oil pump 32 for supplying hydraulic pressure to the pressure accumulator 30 from an oil pan 31, and a 2-port 2 provided in the middle of the oil passage 29. The position type first electromagnetic valve 33 for supply and the two-port two-position type second electromagnetic valve 35 for discharge provided in the discharge passage 34 branched from the oil passage 29 are configured. The solenoid valves 33, 35 are adapted to open and close based on a control signal from an electronic controller (not shown).

The operation of this embodiment will be described below.

That is, when the brake pedal 2 is stepped on and braked during turning of the vehicle or when the vehicle is lightly loaded, the first electromagnetic valve 33 is closed and the second electromagnetic valve 35 is operated to open the inside of the pressure chamber 27. The brake fluid is discharged into the oil pan 31 to bring the pressure chamber 27 into a low pressure state. Therefore, the plunger 26 is biased to the retracted position (right side) by the spring force of the compression spring 17, as shown in FIG.

On the other hand, the brake fluid pressure generated in the master cylinder 1 flows from the primary passage 4 to the through hole 18 of the proportioning valve 11, the first pressure receiving chamber 14 a, the communication passage 20, the second pressure receiving chamber 14 b, and the communication hole 19. Then, the torque is transmitted from the downstream passage portion 4a to the wheel cylinder 3 to generate a braking torque.

At this time, as shown in FIG. 1, the internal pressure of the primary passage 4 (master cylinder internal pressure) is P1, the internal pressure of the downstream passage portion 4a is P2, the second pressure receiving surface 22 of the piston 15, and the first pressure receiving surface 21. , The opening area of the communication passage 20 is A1, A2, A3, the set load of the compression spring 17 is F0, and the spring constant is k, the piston 15 receives the following left and right forces.

Rightward force = P2 (A1-A3) ... (1) Leftward force = P1 (A2-A3) + F0 + kX ... (2) Further, the first and second pressure receiving chambers 14a immediately after the brake pedal 2 is depressed, 14b communicates with each other through the communication passage 20, so P1 = P2. Therefore, the piston 15 gradually moves to the right while keeping the balance of the left and right forces, and the one end opening edge of the communication passage 20 hits the valve body 24 of the check valve 16 to close the one end opening (FIG. 2). reference).

When the pressure at the time when the one end opening edge hits the valve body 24 is P0 and the moving amount of the piston 15 is X0, P0 becomes the following value according to the equations (1) and (2). ..

P0 (A1-A3) = P0 (A2-A3) + F0 + kX0 Therefore, P0 = F0 + kX0 / A1-A2 ... (3) (see FIG. 4). When P1 and P2 reach P0 and then the pressure of P1 further increases, a pressure difference occurs between P1 and P2 in order to maintain the balance of the force of the piston 15, and the pressure relationship is (1) = ( From 2) P2 (A1-A3) = P1 (A2-A3) + F0 + kX0

[0026]

[Equation 1]

It becomes

Therefore, the relationship between P1 and P2 is a linear expression having the slope of A2-A3 / A1-A3 and F0 + kX0 / A1-A3 as the P ₂ intercept, as shown by the alternate long and short dash line in FIG. P2 changes in a state lower than P1.

As a result, the inside of the wheel cylinder 3 is controlled to a low pressure, and the tail swing during turning and the rear wheel lock during light loading are reliably prevented.

On the other hand, when the brake pedal 2 is stepped on and braked during straight traveling in the heavy load state, only the first solenoid valve 33 is opened by the output signal from the controller, and the pressure accumulator 30 is stored in advance. The stored high hydraulic pressure is supplied from the oil passage 29 into the pressure chamber 27, and the pressure chamber 27 becomes high pressure. Therefore, as shown in FIG. 3, the plunger 26 moves forward by a predetermined amount against the spring force of the compression spring 17 to increase the spring force of the compression spring 17 to a predetermined pressure.

Therefore, when the amount of movement of the plunger 26 is L, the balance of the left and right forces of the piston 15 is changed from (1) and (2) to the following.

Rightward force = P2 (A1-A3) ... (5) Leftward force = P1 (A2-A3) + F0 + kX + kL ... (6) Therefore, when the pressures of P1 and P2 are separated, that is, one opening edge is a valve. The split point (P01) that contacts the body 24 and closes the communication passage 20 is P01 = F0 + kX0 + kL / A1-A2 (7), and the relationship between P1 and P2 after P01 is

[0033]

[Equation 2]

It becomes

Therefore, the pressure P2 of the wheel cylinder 3 is increased by the split point P01 by kL / A1-A2 and kL / A1-A3 as shown by the solid line in FIG. 5, and the pressure transition thereafter is kept high. To be done.

Therefore, the braking force on the rear wheel side is sufficiently secured, and the braking distance can be shortened. As a result, the load on the braking device on the front wheel side can be reduced, and the occurrence of a fade phenomenon or the like can be prevented.

Moreover, in this embodiment, since the hydraulic pressure control circuit 28 is not separately provided, but the TCS pressure accumulator 30 or the like is used, the structure can be simplified and downsized, the manufacturing work efficiency is deteriorated, and the cost is reduced. Soaring is sufficiently suppressed.

The present invention is not limited to the above embodiment, and the compression spring 17 can be changed to a leaf spring or the like, for example.

[0039]

[Effect of the device]

 As is clear from the above description, according to the brake fluid pressure control device of the present invention, the spring force of the compression spring of the proportioning valve is appropriately changed by the variable mechanism. In addition to preventing swinging of the tail and locking of the rear wheels during braking during loading, the internal pressure of the wheel cylinders on the rear wheels is kept high during heavy loading and during braking during straight running, so Sufficient control of the wheels can be secured.

As a result, the braking distance can be shortened, the load on the braking device on the front wheel side can be reduced, and the occurrence of a fade phenomenon or the like can be prevented.

[Brief description of drawings]

FIG. 1 is a schematic view of an essential part showing an embodiment of the present invention.

FIG. 2 is a schematic view of a main part showing the operation of the present embodiment.

FIG. 3 is a schematic view of a main part showing still another operation of the present embodiment.

FIG. 4 is a pressure characteristic diagram of the present embodiment.

FIG. 5 is a pressure characteristic diagram of the present embodiment.

FIG. 6 is a schematic view showing a conventional brake fluid pressure control device.

[Explanation of symbols]

1 ... Master cylinder, 2 ... Brake pedal, 3 ... Wheel cylinder, 4 ... Primary passage (hydraulic passage), 1
1 ... proportioning valve, 12 ... variable mechanism, 17
... Spring member (compression spring).

Claims (1)

[Scope of utility model registration request] 1. A master cylinder for generating a brake hydraulic pressure in accordance with the amount of depression of a brake pedal, a hydraulic pressure passage communicating between the master cylinder and each wheel cylinder on the left and right rear wheels, and a downstream of the hydraulic pressure passage. And a proportioning valve for controlling the brake fluid pressure transmitted from the master cylinder to each wheel cylinder via a spring force of a spring member, the brake fluid pressure control device comprising: A brake fluid pressure control device comprising a variable mechanism for varying the force.