JPH06127358A - Brake fluid pressure control device - Google Patents

Abstract

PURPOSE:To eliminate no brake sensation by forming such structure as to close master cylinder communicating ports at the time of antiskid control and to move pistons onto the cylinder chamber side by the differential pressure of brake fluid pressure caused by the increase of the brake fluid pressure so as to increase the volume of control chambers. CONSTITUTION:At the time of antiskid control operation, the spools 31 of flow valves 7, 8 move to close the master cylinder communicating ports 11, 12 of cylinder chambers 9. When a brake pedal is further depressed, the braking pressure of a master cylinder 2 becomes high, so that differential pressure is generated between the braking pressure of the master cylinder 2 and that of the cylinder chambers 9. When this differential pressure reaches the specified value or higher, the spools 31 move onto the cylinder chamber 9 side against the energizing force of piston rings 58, so that the volume of control chambers 50 is increased. A stroke is therefore generated to the master cylinder 2, which results in generating the stroke by the brake pedal. A driver does not therefore have no brake sensation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brake fluid pressure control device for anti-skid control which prevents a tire from falling into a locked state when a brake is operated.

[0002]

2. Description of the Related Art As a brake fluid pressure control device for anti-skid control adopted for the purpose of preventing a tire from falling into a locked state during brake operation, a brake fluid pressure control device for communicating with at least a master cylinder communication port communicating with a master cylinder and a wheel cylinder. A cylinder chamber having a wheel cylinder communication port, and the master cylinder communication port and the wheel cylinder which are slidably provided in the cylinder chamber and are in a stationary position urged by a spool spring when the anti-skid control is not operated. Switching the communication state of the hydraulic control circuit by using a flow valve having a communication port and a spool that moves against the biasing force of the spool spring by a differential pressure generated on both sides during the operation of anti-skid control There is. This flow valve uses a spool that moves when the anti-skid control is activated to prevent the so-called kickback from occurring in the brake pedal under the influence of the pump discharge pressure on the master cylinder side. It is designed to block the communication port.

[0003]

In the above brake fluid pressure control device, the master cylinder communication port is closed by the spool that moves when the anti-skid control is activated. There is no way for the brake fluid to escape and no stroke occurs. Therefore, there is a fear that the driver who operates the brake pedal may have a feeling of no braking (a feeling that the brake is not working).

Therefore, an object of the present invention is to provide a brake fluid pressure control device which does not give a driver a feeling of no braking during anti-skid control.

[0005]

In order to achieve the above object, a brake fluid pressure control device of the present invention is a cylinder having at least a master cylinder communication port communicating with a master cylinder and a wheel cylinder communication port communicating with a wheel cylinder. Chamber and the cylinder chamber so as to be slidable so that the master cylinder communication port and the wheel cylinder communication port communicate with each other at a stationary position urged by a spool spring when anti-skid control is not operated, A flow valve having a spool that moves against the biasing force of the spool spring by a differential pressure generated on both sides during skid control operation to close at least the master cylinder communication port. On the rear end side in the moving direction of the spool. Control chamber that is provided continuously with the master chamber and communicates with the master cylinder, and one end side is provided in the control chamber and the other end side is provided in the cylinder chamber to partition the control chamber and the cylinder chamber. A piston for locating the abutting spool at the stationary position when it is at the movement limit position in the direction opposite to the spool, and urging the piston in the direction opposite to the spool for locating the piston at the movement limit position; And a piston spring that moves the piston in the cylinder chamber direction when the differential pressure between the control chamber side hydraulic pressure and the cylinder chamber side hydraulic pressure applied to the piston exceeds a predetermined value. It is characterized by being provided.

[0006]

According to the brake fluid pressure control device of the present invention, when the anti-skid control is activated, the spool of the flow valve moves to close the master cylinder communication port in the cylinder chamber, and the brake pedal is depressed to cause the master cylinder to move. When the brake fluid pressure increases, the brake fluid pressure of the master cylinder is introduced into the control chamber that is provided continuously to the cylinder chamber at the rear end side of the spool moving direction, and the cylinder chamber that is partitioned from the control chamber by the piston. When the differential pressure between the brake fluid pressure and the brake fluid pressure becomes larger than a predetermined value, the piston that was biased by the piston spring and was in the movement limit position in the direction opposite to the spool resists the biasing force of the piston spring due to this differential pressure, and Will move to the side of the moving cylinder chamber. Therefore, the volume in the control chamber increases as the hydraulic pressure on the master cylinder side increases.

Further, when the spool is not in the moving state, the master cylinder communication port is opened, so that substantially the same hydraulic pressure is introduced into the control chamber and the cylinder chamber, so that the piston has a piston spring. It does not move against the forces and the volume in the control room does not change when the anti-skid control is inactive.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A brake fluid pressure control device according to an embodiment of the present invention will be described below with reference to FIG. In addition, the upper and lower sides used in the following description are used for convenience sake.

In the drawing, reference numeral 1 is a brake hydraulic pressure control device for anti-skid control, reference numeral 2 is connected to a brake pedal 3, and hydraulic pressure is generated in response to the depression of the brake pedal 3, and the like, respectively. 2 shows a tandem master cylinder having two hydraulic pressure generating chambers 2A and 2B that are transmitted to hydraulic pressure control circuits A and B of two systems. Since the hydraulic pressure control circuit B side has the same configuration as the hydraulic pressure control circuit A side, only the hydraulic pressure control circuit A side will be described.

The hydraulic control circuit A is further divided into two branch systems connected to the front wheel cylinder 4a and the rear wheel cylinder 4b, respectively. That is, the hydraulic control circuit A is divided into two branch system paths 5 and 6 after exiting from the hydraulic pressure generating chamber 2A of the master cylinder 2, and the flow valves 7 and 8 are provided in the paths 5 and 6, respectively. Are provided respectively. Each of the flow valves 7 and 8 has a cylinder chamber 9 that extends in the up-down direction and has a circular cross section orthogonal to the extending direction, and a plurality of ports that communicate the cylinder chamber 9 with the outside. Casing 10
It is equipped with. In addition, the wheel cylinders 4a, 4b
Is a hydraulic actuator used for a disc brake and a drum brake.

Here, the above-mentioned port is a first port (at a predetermined position) provided at a predetermined position orthogonal to the axis of the cylinder chamber 9 so as to communicate with the hydraulic pressure generating chamber 2A via the paths 5 and 6 of each branch system. Master cylinder communication port) 11, the first port 1
A second port (master cylinder communication port) 12 which is provided at a predetermined position below 1 in parallel with the first port 11 and communicates with the first port 11 outside, and a second port 12 provided below the second port 12 by a predetermined amount. A third port (wheel cylinder communication port) 13 communicating with the wheel cylinders 4a, 4b via paths 13a, 13b of the same branch system, and a third port provided at the lower end of the cylinder chamber 9 along the axial direction of the cylinder chamber 9 The fifth port 15 is provided by arranging the axes on the same plane as the axes of the four ports 14 and the second port 12.

The third port 13 is the first port 1
1. Upper port 1 provided parallel to the lower side of a predetermined amount of 1
6 and a middle port 17 provided on the lower side of the upper port 16 by a predetermined amount in parallel therewith and communicating with the upper port 16 on the outside.
And a lower port 18 which is provided below the middle port 17 by a predetermined amount in parallel therewith and which communicates with the upper port 16 and the middle port 17 on the outside.

Here, the fourth port 14 of each flow valve 7, 8 is connected to each of the paths 19, 20 of each branch system, on which the electromagnetic normally closed valve 2 is connected.
1, 22 are provided respectively. And route 1
9 and 20 meet at a meeting point 23, and this meeting point 23
One reservoir 24 having a variable capacity is provided so as to be connected to. Further, the fifth ports 15 of the flow valves 7 and 8 are connected to each other by a path 25, and a path 26 is provided between the path 25 and the path 20 between the reservoir 24 and the electromagnetic normally closed valve 22. A pump 27 is provided on the path 26 which is connected. Here, this pump 27
Is a pump main body 28 for performing suction and discharge, a suction valve 29 provided on the reservoir 24 side of the pump main body 28, and a discharge valve 3 provided on the side opposite to the reservoir 24 of the pump main body 28.
0, and the brake fluid from the reservoir 24 side is sucked and discharged to the path 25 side.

A cylindrical spool 31 is fitted in the cylinder chamber 9 of the casing 10 of the flow valves 7 and 8 so as to be vertically slidable. This spool 3
Reference numeral 1 denotes an upper hole 32 having a predetermined diameter bored in the center from the upper end to a predetermined intermediate position along the axial direction, and has the same diameter as the upper hole 32 bored from the lower end to a predetermined intermediate position. In addition, it has a lower hole 33 which is always communicated with the fourth port 14, and the upper hole 32 and the lower hole 33 are communicated with each other through a small-diameter hole 34 having a smaller diameter than the above. The diameter of the opening 35 at the lower end of the lower hole 33 is larger than the other parts by a predetermined amount, and a spool spring 36 for urging the spool 31 upward with a predetermined urging force is provided in the opening 35. The top end is inserted.

A plurality of holes are formed in the spool 31 at right angles to the upper hole 32 and the lower hole 33. These holes are provided below the upper end of the spool 31 by a predetermined amount, and when the spool 31 is in a stationary state in which the spool 31 is urged (state of the flow valve 7 shown in FIG. 1: described later). When the upper hole 32 and the first port 11 are communicated with each other, and the spool 31 is moved downward due to the differential pressure generated on both sides during the anti-skid control (the state of the flow valve 8 shown in FIG. 1). First port 11 and second port 12 and upper hole 32
A first hole 37 that blocks communication with the upper hole 32 and a predetermined amount lower than the first hole 37 so that the upper hole 32 communicates with the upper port 16 of the third port 13 when the spool 31 is in the stationary state. A second hole 38 that blocks the communication between the upper hole 32 and the upper port 16 when the spool 31 is in the above-described moving state, and the spool 31 is provided a predetermined amount below the second hole 38 and is in the above-mentioned stationary state. At some time, the communication between the lower hole 33 and the middle port 17 and the lower port 18 of the third port 13 is blocked, and when the spool 31 is in the moving state, the lower hole 33, the middle port 17 and the lower port 18 are connected.
And a third hole 39 for communicating with the first hole 37, and when the spool 31 is in the stationary state, it blocks communication between the upper hole 32 and the fifth port 15, and The upper hole 32 and the fifth port 15 are communicated with each other when in the above-described moving state, and when the spool 31 further moves downward, the communication is restricted (fine communication or cutoff).
This is the fourth hole 40.

Here, for convenience, the first hole 37 and the fourth hole 40 are provided.
However, since there is a groove 41 on the outer circumference of the spool 31, there is no difference between the two, and of course only one may be provided, and the same applies to the second hole 38 and the third hole 39. Further, grooves 42a and 42b are provided on the outer circumference of the spool 31, respectively. The lower hole 33 is formed in the third hole 39.
A small hole 43 having a diameter slightly larger than the small diameter hole 34 is provided in a communicating portion with
Is provided. Further, on the outer peripheral portion of the spool 31 on the lower side of the first hole 37 by a predetermined amount, there is provided a small groove 44 that minutely communicates the second port 12 and the fifth port 15 when the spool 31 is in the stationary state. The second port 12 and the fifth port 15 are provided on the outer peripheral portion on the upper side by a predetermined amount of the hole 37 when the spool 31 is in the anti-skid control re-pressurized state (state of the flow valve 8 shown in FIG. 1). A small groove 45 is provided to allow minute communication, but these always maintain mutual communication in the brake circuit or a relief valve 46 described later.
It acts as an extremely small throttle provided for the purpose of fail-safe, and is not a large throttle that returns excessive discharge from the pump 27 during anti-skid control to the hydraulic pressure generating chamber 2A side.

In the present embodiment, the control chamber 50 having a diameter larger than the cylinder chamber 9 by a predetermined amount is continuous with the cylinder chamber 9 on the upper side of the cylinder chamber 9, that is, on the rear end side in the moving direction of the spool 31. Is provided. This control room 5
0 is the path 5 or 6 on the hydraulic pressure generating chamber 2A side via the path 51.
A piston 52 is provided on the control chamber 50 side and the cylinder chamber 9 side of the control chamber 50. The piston 52 has a shaft portion 53 having substantially the same diameter as that of the cylinder chamber 9 and slidably fitted therein. The shaft portion 53 has a larger diameter at its upper end and a smaller diameter than the control chamber 50. The flange portion 54 is integrally formed. The flange portion 54 is provided near the lower end of the shaft portion 53 and the upper end wall 5 of the control chamber 50.
A seal member 57 is provided that always divides the control chamber 50 and the cylinder chamber 9 into a dense space within a range of movement from the position where the control chamber 50 abuts against the position 5 to the position where the lower end wall 56 abuts. Further, between the flange portion 54 and the lower end wall 56 of the control chamber 50, the piston 52 is urged upward, that is, in the direction opposite to the spool 31, and the piston 52 is brought into contact with the upper end wall 55 of the control chamber 50 to move upward. A piston spring 58 that is located at the limit position is provided.

Here, when the spool 31 comes into contact with the lower end surface of the piston 52 by the urging force of the spool spring 36 when the piston 52 is at the upper movement limit position, the spool 31 becomes the above-mentioned stationary state. When the differential pressure between the hydraulic pressure on the control chamber 50 side and the hydraulic pressure on the cylinder chamber 9 side exerted on the piston 52 when the spool 31 is in the moving state exceeds a predetermined value, the piston 52 causes the piston spring 58 to urge. It is designed to move in the direction of the cylinder chamber 9 against.
That is, when the spool 31 is in a stationary state, the first port 11 is opened, the brake hydraulic pressure on the hydraulic pressure generating chamber 2A side is introduced to the upper hole 32 side of the cylinder chamber 9, and the small diameter hole 34 is used. Wheel cylinder 4 with a large flow path without
Since it is transmitted to the control chamber 50, the hydraulic pressure of the hydraulic pressure generating chamber 2A introduced into the control chamber 50 becomes substantially equal to the brake hydraulic pressure on the upper hole 32 side of the cylinder chamber 9, and the piston spring 58 is applied to the piston 52. When the spool 31 moves, the first port 11 and the second port 12 are closed and the hydraulic pressure generating chamber 2A is not generated.
Side brake fluid pressure is not introduced to the upper hole 32 side of the cylinder chamber 9, and when the hydraulic pressure on the hydraulic pressure generating chamber 2A side further increases in this state, a differential pressure that causes the piston 52 to contract is generated. Will occur.

The set load of the piston spring 58 does not move the piston 52 when the spool 31 is in the stationary state as described above, and the spool 3 does not move.
1 becomes a moving state, the first port 11 and the second port 12 are closed, and in this state, when the brake fluid pressure generated from the fluid pressure generating chamber 2A becomes higher, that is, the brake pedal 3 is further depressed. The value may be any value that allows the piston 52 to move at this point (the differential pressure generated in the piston 52 at this time exceeds the above-mentioned predetermined value), but if this value is small, the piston 52 will move when the anti-skid control operation starts. Since it will move, it is preferable that the set load be large to some extent. Also, the piston 5
The moving length of 2 is such that the groove 4 of the first hole 37 at the stationary position of the spool 31 does not interfere with the spool 31 during movement.
The length is preferably smaller than the length from the upper end of 1 to the lower end of the second port 12.

A path 60 is connected between the confluence 23 and the path 6, and the relief valve 4 is connected to the path 60.
6 is provided. The relief valve 46 is separately connected to the hydraulic pressure generating chamber 2A, the suction side of the pump 27, and the discharge side of the pump 27, and urges the valve body 61 by the spring 62 and the spring 63. The shaft member 64 is in contact with the valve body 61, and the hydraulic pressure generating chamber 2A
The brake fluid pressure on the side is applied to the valve body 61 in the closing direction via the shaft member 64. As a result, when the discharge pressure of the pump 27 becomes higher than the pressure on the hydraulic pressure generating chamber 2A side by the biasing force of the springs 62 and 63, the valve is opened to allow the excess discharge pressure to escape to the suction side of the pump 27. . Further, inside the relief valve 46, there is provided a cup 65 for flowing the brake fluid to the hydraulic pressure generating chamber 2A side when the brake hydraulic pressure on the hydraulic pressure generating chamber 2A side becomes low.

Next, the operation of the brake fluid pressure control device 1 of the present embodiment having the above-mentioned structure will be described below in order.

First, the spool 31 of the flow valve 7, 8 in the non-operation state of the anti-skid control has the first port 11, the first hole 37, the upper hole 32, the second hole 38 and the upper port of the third port 13. The hydraulic pressure generating chamber 2A is communicated with the wheel cylinders 4a and 4b of the same branch system via 16 and the normal operation, that is, the wheel cylinders 4a and 4b are pressurized in a large flow path in accordance with the depression of the brake pedal 3 or the like. It is like this. Here, at this time, the third hole 39 and the fourth hole 40 are in a state of being disconnected from any of the ports on the outer peripheral side.

At this point in time, the brake fluid pressure introduced into the control chamber 50 and the brake fluid pressure on the upper hole 32 side of the cylinder chamber 9 are substantially equal, so that the piston 52 acts on the urging force of the piston spring 58. It does not move against and maintains the state of being in contact with the upper end wall 55 of the control chamber 50. Therefore, when the anti-skid control is not operated, that is, during normal braking, the volume in the control chamber 50 does not change, and the stroke of the brake pedal 3 does not extend.

When the anti-skid control depressurization operation is started, the electromagnetic normally-closed valves 21 and 22 are opened so that the brake fluid existing in the portion surrounded by the lower hole 33 and the lower portion of the casing 10 is released. Flows into the reservoir 24, and the resulting differential pressure on both sides of the spool 31 (the upper hole 32 side and the lower hole 33 side) causes the spool 31 to have a small diameter hole 34.
The first port 11 and the second port 12 and the communication between the first hole 37 and the third port, and the wheel cylinders 4a and 4b and the reservoir 24 are connected to the third port. 13 through the middle port 17 and the lower port 18 and the third hole 39 and the lower hole 33 to allow the brake fluid in the wheel cylinders 4a, 4b to flow into the reservoir 24, thereby increasing the brake fluid pressure in the wheel cylinders 4a, 4b. It is designed to reduce the pressure.

The pump 27 is always in a driving state during the anti-skid control, and the fifth port 15 of the casing 10 of the flow valves 7 and 8 and the fourth hole 40 of the spool 31 are in the depressurized state. The communication is restricted, and the brake fluid in the reservoir 24 sucked and discharged by the pump 27 is returned to the reservoir 24 side via the relief valve 46 when the discharge pressure becomes higher than a predetermined pressure, and At the time of re-pressurization in anti-skid control, the electromagnetic normally closed valves 21 and 22 are closed, so that the fifth port 15 of the flow valves 7 and 8 and the fourth hole 40, the upper hole 32, and the small diameter hole 34 that are in slight communication therewith. , The lower hole 33, the third hole 39, and the middle port 17 and the lower port 18 of the third port 13 to re-pressurize the wheel cylinders 4a and 4b at a substantially constant flow rate. It has become way.

During depressurization and repressurization of the anti-skid control, the spool 31 moves downward to block the communication between the first port 11 and the second port 12 and the first hole 37. , The brake fluid pressure on the hydraulic pressure generating chamber 2A side is not introduced to the upper hole 32 side of the cylinder chamber 9, and in this state the fifth port 15 and the cylinder chamber 9 are restricted from communicating with each other and through the small diameter hole 34. The substantially constant flow rate from the upper hole 32 side of the spool 31 to the lower hole 3
Since it flows to the 3 side, the hydraulic pressure acting on the lower surface of the piston 52 becomes lower than the hydraulic pressure on the hydraulic pressure generating chamber 2A side. In this case, if the hydraulic pressure difference does not exceed the above-mentioned differential pressure, the piston 5
2 does not move. When the hydraulic pressure on the hydraulic pressure generating chamber 2A side further increases in this state, a differential pressure that causes the piston 52 to contract is generated in the piston 52. Then, the piston 52
Moves to the cylinder chamber 9 side where the spool 31 is in the moving state, and as a result, the volume in the control chamber 50 increases in accordance with the increase in the hydraulic pressure generated from the hydraulic pressure generating chamber 2A. 2 can be stroked, so that the brake pedal 3 can be stroked so that the driver does not feel no braking.

In the present embodiment, the case where the communication between the fifth port 15 and the cylinder chamber 9 is cut off when the anti-skid control is not operated, that is, when the spool 31 is stationary, has been described as an example. In the pressure control circuit A, since the pump 27 is shared by both wheel cylinders 4a and 4b, when only one side of the wheel cylinders 4a and 4b enters the anti-skid control state, the flow valve provided on the other side is provided. The purpose is to prevent the discharge pressure of the pump 27 from returning to the hydraulic pressure generating chamber 2A side through the pump 27. In the case where the pump 27 is individually provided, when the spool 31 is stationary, the fifth port 15 and the cylinder chamber It is also possible to employ a device that establishes communication with 9.

[0028]

As described in detail above, according to the brake fluid pressure control device of the present invention, the brake fluid pressure on the master cylinder side is further increased when the master cylinder communication port is closed during the operation of the anti-skid control. When it becomes higher, the differential pressure between the brake fluid pressure on the control chamber side and the brake fluid pressure in the cylinder chamber acting on the piston becomes larger than a predetermined value, and the piston moves to the cylinder chamber side at this differential pressure. The volume in the control chamber increases as the hydraulic pressure on the master cylinder side increases. Therefore, a stroke can be generated in the master cylinder, so that the brake pedal does not generate a stroke and the driver does not feel no braking.

Moreover, when the anti-skid control is not in operation, the spool is not in a moving state and the master cylinder communication port is opened, so that substantially the same hydraulic pressure is introduced into the control chamber and the cylinder chamber. Therefore, the piston does not move and the volume in the control chamber does not change. Therefore, the pedal stroke does not extend during normal braking.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a brake fluid pressure control device according to an embodiment of the present invention.

[Explanation of symbols]

 1 Brake Fluid Pressure Control Device 2 Master Cylinder 4a, 4b Wheel Cylinder 7, 8 Flow Valve 9 Cylinder Chamber 11 First Port (Master Cylinder Communication Port) 12 Second Port (Master Cylinder Communication Port) 13 Third Port (Wheel Cylinder Communication) Port) 31 Spool 36 Spool spring 50 Control chamber 52 Piston 58 Piston spring

Claims (1)

[Claims] 1. A cylinder chamber having at least a master cylinder communication port communicating with the master cylinder and a wheel cylinder communication port communicating with the wheel cylinder, and a spool provided slidably in the cylinder chamber when the anti-skid control is not operated. The master cylinder communication port and the wheel cylinder communication port communicate with each other at a stationary position biased by a spring, and move against the biasing force of the spool spring by the differential pressure generated on both sides when the anti-skid control is activated. In the brake fluid pressure control device including a flow valve having at least a spool that closes the master cylinder communication port, the flow valve is provided continuously to the cylinder chamber on the rear end side in the moving direction of the spool. Together with the master cylinder Control chamber, and one end side is provided in the control chamber and the other end side is provided in the cylinder chamber to partition the control chamber and the cylinder chamber, and to abut at the movement limit position in the direction opposite to the spool. A piston for locating the spool at the stationary position, and a control chamber for urging the piston in a direction opposite to the spool so as to be at the movement limit position and for the piston when the spool is in a moving state. A brake fluid pressure control device comprising: a piston spring that moves the piston in the cylinder chamber direction when a pressure difference between the hydraulic pressure on the side of the cylinder chamber and the hydraulic pressure on the side of the cylinder chamber exceeds a predetermined value.