KR100328223B1 - Hydraulic shuttle valve of brake traction control system - Google Patents

Abstract

The present invention relates to a reciprocating hydraulic valve of a brake traction control system, the object of which is to compactly improve the internal structure of the hydraulic valve to reduce the manufacturing cost.

The reciprocating hydraulic valve 60 of the brake traction control system according to the present invention is provided with a rubber member valve member 65 in the head portion of the plunger 64 is built in the valve housing 61, the upper and lower sides of the plunger 64 According to the movement, the communication between the discharge port 120 and the suction port 110 is directly controlled.

Since the plunger 64 is compactly embedded in the valve housing 61, the manufacturing cost of the reciprocating hydraulic valve 60 as a whole is reduced, as well as the assemblability is improved.

Description

Hydraulic shuttle valve of brake traction control system

The present invention relates to a brake traction control system, and more particularly, when a slip phenomenon occurs during vehicle acceleration, an opening operation is performed so that hydraulic pressure by a motor drive is transmitted to a hydraulic brake side, and when a braking hydraulic pressure is transmitted by a driver over a predetermined pressure. A reciprocating hydraulic valve of a closed actuation brake traction control system.

The vehicle is essentially equipped with a brake system for braking. Recently, various types of systems have been proposed and used to obtain a stronger and more stable braking force, and among these, an anti-lock brake system has a progressive effect.

The anti-lock brake system is equipped with a drum or caliper hydraulic brake that generates braking force by hydraulic pressure on the front wheel and the rear wheel, respectively.A master cylinder equipped with a hydraulic power and a storage tank and an oil storage tank are formed to form a braking hydraulic pressure to the hydraulic brake side. It consists largely of solenoid valves provided at the inlet side and the outlet side to control hydraulic pressure transfer to the brake side, modulators and ECUs for controlling them.

The solenoid valve is provided on the inlet side and the outlet side of each hydraulic brake to control the oil pressure transmitted to the hydraulic brake side. This is divided into a normally open solenoid valve (hereinafter referred to as a NO solenoid valve) disposed at the inlet side and a normally closed solenoid valve (hereinafter referred to as an NC solenoid valve) arranged at the outlet side. This results in a strong and stable braking force. At this time, the ECU senses the vehicle speed through wheel sensors provided at the front wheel and the rear wheel, respectively, and controls the opening and closing operations of each solenoid valve.

On the downstream side of the NC-type solenoid valve on the front wheel side and the rear wheel side, the first and second low pressure accumulators are independently installed to temporarily store oil discharged from each brake in the decompression mode. In addition, the first and second high pressure accumulators are installed at the rear of the first and second low pressure accumulators, and the first and second pumps driving one motor are disposed therebetween. The low pressure oil stored in the low pressure accumulator is pressurized and pumped to the first and second high pressure accumulators. The first and second low pressure accumulators, the first and second pumps, the first and second high pressure accumulators, the solenoid valves, and the like are compactly installed in the modulator block.

In the conventional anti-lock brake system configured as described above, when the driver presses the brake pedal while driving, the back force is generated by the pressure difference in the power booster, and the master cylinder receives the amplified force to form the hydraulic pressure. This hydraulic pressure is transmitted to the respective hydraulic brakes provided on the front wheel and the rear wheel through the NO-type solenoid valve to perform a braking action.

At this time, if excessive braking pressure is transmitted than road condition, a kind of slip phenomenon occurs that the tire of the vehicle stops rotating and slips, and this phenomenon is detected by the wheel sensor mounted on the wheel of the vehicle and applied to the ECU of the anti-lock brake system. Delivered. Subsequently, the ECU operates to open the orifice by applying current to the solenoid of the NC solenoid valve. Therefore, the oil in the hydraulic brake wheel cylinder is released and the braking force is reduced, thereby preventing the slip phenomenon.

The oil discharged through the NC-type solenoid valve is moved to the first and second low pressure accumulators and stored for a while, and when the boost mode is required, the pressure is increased again through the first and second pumps as the motor is driven. The first and second high pressure accumulators and the master cylinder or NO solenoid valve are circulated again.

Meanwhile, recently, a brake traction control system (BTCS) is additionally configured in the ABS device to prevent slippage when starting the vehicle while stepping on the accelerator pedal.

The brake traction control system constitutes a separate hydraulic line connecting the brake hydraulic outlet line of the master cylinder and the inlet hydraulic line of the pump, and is equipped with a hydraulic suttle valve for opening and closing the hydraulic line. That is, the reciprocating hydraulic valve is operated to close the hydraulic line when the driver presses the brake pedal and the brake hydraulic pressure is transmitted while maintaining the normally open state.

Therefore, when the driver steps on the acceleration pedal and slippage occurs due to slippery conditions at the start of the vehicle, the vehicle is easily started by transmitting a slight braking hydraulic pressure to the hydraulic brake. At this time, the oil supply is made through a reciprocating hydraulic valve that is open.

In other words, if a slip phenomenon is detected by the ECU during vehicle acceleration, the pump is driven by driving the motor. Accordingly, the oil on the master cylinder side flows into the pump side through the open reciprocating hydraulic valve, and is pressurized and supplied into the high pressure accumulator. Subsequently, the inlet pressure is transmitted to the hydraulic brake side through the open-type NO solenoid valve, so that a predetermined lock is applied to the wheel when the vehicle starts while the accelerator pedal is pressed. Therefore, even if the driver unconsciously presses the accelerator pedal and starts the vehicle, the vehicle starts slowly because a predetermined lock is applied to the wheel.

On the other hand, when the driver presses the brake pedal and the braking action is performed, the reciprocating hydraulic valve is closed by the braking hydraulic pressure to prevent the braking hydraulic pressure transmission to the pump side, the internal structure of which is illustrated in FIG. 1.

Conventional reciprocating hydraulic valves, as shown therein, the operation pin (3), valve core reciprocating up and down at the inner bottom of the bore (2) processed in the block (1), wrapped with a valve member (4) of rubber material Plunger (8), which is connected to the upper end of the operating pin (3) through the connecting bar (6), the connecting bar (6), which is installed in the axial direction in the oil passage (5b) of the (5), The diaphragm 7 of the mold product, which is installed between the lower end of the plunger 8 and the upper end of the connecting bar 6, partitions the space therebetween up and down, and protrudes downward from the center to elastically bias the connecting bar 6 downward. It is largely comprised.

Accordingly, the connecting bar 6 and the operating pin 3 are lowered by the elastic bearing force of the plunger 8 which is normally supported by the return spring 8a in the downward direction and the diaphragm 7 which is formed with the central portion convex downward. By being supported in the direction, the front end surface 4a of the valve member 4 is kept in a state spaced apart from the lower surface 5a of the valve core 5. As a result, the suction port 2a and the discharge port 2b communicate with each other through the oil passage 5b formed at the center of the valve core 5, thereby driving the pump (not shown) without stepping on the brake pedal (not shown). According to the need for oil, the master cylinder (not shown) side and the pump inlet side (not shown) are linked to form an oil supply passage.

On the other hand, when the driver presses the brake pedal (not shown), a part of the braking hydraulic pressure flows into the bore 2 through the suction port 2a. When the oil pressure is 4 bar or more, the diaphragm 7 and The plunger 8 rises upward while winning the elastic force of the return spring 8a. Therefore, the actuating pin 3 is also raised by the elastic force of the spring 3a so that the front end surface 4a of the valve member 4 blocks the oil passage 5b in close contact with the lower surface 5a of the valve core 5, thereby allowing suction. Communication between the port 2a and the discharge port 2b is cut off.

However, such a conventional reciprocating hydraulic valve has an elastic biased connection bar 6 and an operation pin 3 downward through a diaphragm 7 so that the suction port 2a and the discharge port 2b are opened when the brake is inoperative. It is configured to maintain the state, such a diaphragm (7) is an injection molded product through a mold, the manufacturing process is difficult, resulting in the rise of the reciprocating hydraulic valve manufacturing cost.

In addition, the diaphragm 7, which is a mold product, requires a number of processes in which the edge portion is pressed onto the upper end of the valve core 5 in order to prevent oil leakage, and thus, the assembly thereof is also lowered. Since the pram 7 is designed, there is a limit to compacting the product.

The present invention is to solve this problem, an object of the present invention is to allow the inlet port and the discharge port to be directly opened and closed by the plunger reciprocating up and down depending on whether the braking hydraulic pressure transmission, it is possible to compact the internal structure thereof To provide a reciprocating hydraulic valve of a brake traction control system.

1 is a cross-sectional view showing the internal structure of a conventional reciprocating hydraulic valve.

Figure 2 is a hydraulic system diagram of a brake traction control system to which the present invention is applied.

3 is a cross-sectional view of the reciprocating hydraulic valve according to the present invention.

Figure 4 is a perspective view of the plunger of the reciprocating hydraulic valve according to the present invention.

5 is a cross-sectional view showing an operating state of the reciprocating hydraulic valve according to the present invention.

* Description of symbols on the main parts of the drawings *

60. Reciprocating hydraulic valve 61. Valve housing 62. Cylinder

621..Small diameter part 622..Daekyung part 623..Discharge hole

63. Stepped surface 64. Plunger 65. Valve member

66. Filter element 67. Operating spring 68. Return spring

69..Dust Cover

In order to achieve the above object, the present invention provides a valve housing and a valve housing in which a cylinder composed of a large diameter portion and a small diameter portion is formed therein so as to be coupled to a bore processed in a modulator block and connected to a suction port associated with a discharge side of a master cylinder. The discharge hole is drilled to connect the suction port and the discharge port connected to the inlet side of the pump in the neck part, and it is located in the large diameter part of the valve housing, and when the braking hydraulic pressure is transmitted through the suction port, the sealing part provided at the upper part is connected to the large diameter part and the small diameter part. A plunger, a plunger, which is fitted with a valve member elastically biased upward through an operating spring to close the discharge hole and closes the discharge hole, and the valve member is fitted to the head portion and is capable of moving up and down in the small diameter portion of the cylinder. Is provided on the upper side of the valve and if the braking hydraulic pressure is not transmitted through the suction port, A return spring elastically biases the plunger downwardly so as to be spaced apart from the additional step surface, and when the discharge hole is opened by the elastic force of the return spring, the diameter is reduced on the outer circumferential surface of the head portion of the plunger so that oil is discharged through the discharge hole. It is characterized by including a stepped portion.

Hereinafter, one preferred embodiment according to the present invention will be described in detail with reference to the accompanying drawings. 2 is a hydraulic system diagram of a brake traction control system to which the present invention is applied, and FIGS. 3 and 4 are perspective views showing a sectional view and a plunger showing the internal structure of the reciprocating hydraulic valve according to the present invention.

When the brake traction control system (BTCS) is subjected to the acceleration pedal and slippage occurs due to slippery road conditions when the vehicle starts, the ABS pump is driven even if the driver does not step on the brake pedal to lock the wheel. By walking the vehicle, the departure of the vehicle is to be made safely.

2 and 3, the brake traction control system has a separate hydraulic line 50 connecting the hydraulic outlet side of the master cylinder 12 and the inlet side of the pump 42 to the ABS hydraulic system diagram. The reciprocating hydraulic valve 60 is provided therein, and the TC solenoid valve 70 is connected to the hydraulic line 51 connecting the hydraulic outlet side of the master cylinder 12 and the outlet side of the high pressure accumulator 43. ), And their detailed structure is as follows.

First, the vehicle is equipped with a hydraulic brake (20) on the wheel side, each of the master to convert the force to the braking hydraulic pressure and the power unit 11 and forming a force using the pressure difference according to the brake pedal (10) operation The cylinder 12 etc. are comprised. The master cylinder 12 and the hydraulic brake 20 are connected through a hydraulic line, which is connected to the hydraulic brake 20 from the master cylinder 12 to the hydraulic brake 20 in the hydraulic brake 20 according to the flow path and ABS control. A flow path for guiding hydraulic pressure to the master cylinder 12 is configured separately.

Solenoid valves 30 and 31 for controlling the braking hydraulic pressure are provided on the inflow side and the discharge side hydraulic lines of the hydraulic brakes 20, and the inlet side is normally open solenoid valves 30 (hereinafter referred to as NO solenoid valves). On the outlet side, a normal closed solenoid valve (31, called an NC type solenoid valve) is installed. The opening and closing operation of the solenoid valves 30 and 31 is controlled by an ECU (not shown), which is operated based on a signal input from a wheel sensor (not shown). In the discharge line of the NC type solenoid valve 31, oil stored in the low pressure accumulator 40 and the low pressure accumulator 40 in which the hydraulic pressure released from the hydraulic brake 20 is temporarily stored are disposed on the rear side thereof. A pump 42 for pumping pressure by the high pressure accumulator 43 is disposed.

On the other hand, the TC solenoid valve 70 is installed in the hydraulic line 51 connecting the outlet side of the high-pressure accumulator 43 and the outlet side of the master cylinder 12, which is normally open and is normally open. When the vehicle slip is detected as maintaining the state, the vehicle is closed by the ECU (not shown). In addition, a separate hydraulic line 50 directly connecting the outlet side of the master cylinder 12 and the inlet side of the pump 42 is configured, and a reciprocating hydraulic valve 60 is configured here. The reciprocating hydraulic valve 60 also maintains its normally open state and closes when the driver presses the brake pedal 10 and brake oil pressure of 4 bar or more is transmitted therein, thereby supplying oil to the pump 42. Block the flow path.

As shown in FIGS. 3 and 4, the reciprocating hydraulic valve 60 performing this function is compactly provided with a plunger 64 which moves up and down inside the valve housing 61 to close the discharge hole 623. It is built in, it is press-coupled to the bore 130 processed in the modulator block 100.

First, the bore 130 is processed to be the same as the diameter of the valve housing 61 in the modulator block 100 on the rectangular parallelepiped made of aluminum material, the suction port 110 in which oil is introduced to the bottom side is formed in the center of the inner peripheral surface The discharge port 623 to guide the oil to the pump 42 inlet side.

In the valve housing 61, a cylinder 62 having an open lower surface is formed therein, and an air hole 612 is perforated to communicate with the outside at the center of the closed upper surface. The discharge hole 623 is drilled in the center of the valve housing 61 so that the inside of the cylinder 62 and the discharge port 120 communicate with each other. The upper portion of the cylinder 62 in which the discharge hole 623 is formed is made smaller in diameter than the lower end, so that the cylinder 62 is divided into a large diameter portion 622 and a small diameter portion 621. That is, the cylinder 62 has a small diameter portion 621 formed on the upper side of the valve housing 61 and the large diameter portion formed on the lower side of the valve housing 61 so as to smoothly flow oil so that the plunger 64 moves forward and backward. 622). Reference numeral 63 is a stepped surface forming a boundary between the small diameter portion 621 and the large diameter portion 622, the discharge hole 623 is drilled in the horizontal direction on the small diameter portion 621 of the upper portion of the stepped surface 63. .

On the closed upper surface of the valve housing 61, an air hole 612 is drilled to prevent vacuum formation, and a dust cover 69 is provided to prevent foreign substances from entering through the air hole 612. The dust cover 69 is formed in a disc shape, and a portion of the outer circumference of the dust cover 69 is fixed through the caulking portion 691 at the upper edge portion of the valve housing 61.

The plunger 64 slides up and down in the small diameter portion 621 of the valve housing 61 according to whether the braking hydraulic pressure is transmitted. The diameter of the plunger 64 is in the outer peripheral surface of the head portion adjacent to the discharge hole 623 of the small diameter portion 621. The reduced stepped portion 641 is provided. Therefore, the oil flowing into the cylinder 62 through the suction port 110 is discharged to the outside through the gap between the step portion 641 and the small diameter portion 621 and the discharge hole 623 and the discharge port 120. .

The head portion of the plunger 64 is fitted with a rubber valve member 65 is coupled to operate with the plunger 64, when the plunger 64 is raised to the upper surface of the valve member 65 stepped surface (63) In close contact with each other, communication between the suction port 110 and the discharge port 120 is blocked.

That is, a sealing portion 652 protruding in an annular shape is formed on the upper surface of the valve member 65. When the plunger 64 is raised upward, the sealing portion 652 is in close contact with the step surface 63 and the cylinder 62 The small diameter part 621 and the large diameter part 622 of () are partitioned off. In order to fix the valve member 65, an annular recessed recessed groove 643 is formed on the outer circumferential surface of the head of the plunger 64, and the fixing protrusion 651 protrudes in an annular shape from the valve member 65. have. Therefore, the valve member 65 is firmly fixed to the plunger 64 head by fitting the fixing protrusion 651 into the fixing groove 643.

In addition, a return spring 68 is provided inside the plunger 64 to elastically support it downward. One end of the return spring 68 is supported in contact with the upper portion of the small diameter portion 621 and the other end is supported in the inner bottom portion. When the brake pedal 10 is not stepped on, the sealing portion 652 of the valve member 65 is closed. The vehicle 63 is kept spaced apart from the vehicle 63 by a predetermined distance 't'. As a result, the oil passage is formed by a predetermined distance 't', and 't' is a moving distance that the actual plunger 64 can move up and down. Reference numeral 642 is an O-ring coupled to the outer circumferential surface of the plunger 64 to prevent oil leakage.

On the other hand, an open lower surface of the valve housing 61 is provided with a mesh filter member 66 to prevent foreign substances from entering. The filter member 66 is provided with a support part 661 protruding upward in the center in the center, and is composed of a catching part 662 that prevents the inflow of foreign substances by forming the edge portion of the mesh. The outer circumferential end of the locking portion 662 is fitted into the fitting groove 611 formed at the lower end of the valve housing 61 so that the filter member 66 is firmly coupled to the opening of the valve housing 61.

The support portion 661 is in contact with the central portion of the lower surface of the valve member 65 to prevent it from further descending downwards. In addition, the outer side of the support portion 661 is provided with an operating spring 67 for elastically supporting the lower surface of the valve member 65, which is preferably configured to have a weak elastic modulus of the return spring (68).

As such, the plunger 64 provided with the valve member 65, the operation spring 67 supporting the same, and the filter housing 66 having the valve housing 61 compactly embedded in the cylinder 62 are provided with a modulator block 100. Insertion into the bore 130 of the reciprocating hydraulic valve 60 is completed, the plunger 64 is supported downward by the elastic bearing force of the return spring 68 has a relatively large modulus of elasticity. Accordingly, the central portion of the valve member 65 is in contact with the upper end of the support portion 661 while compressing the operation spring 67, and the sealing portion 652 of the valve member 65 has a stepped surface 63 and a moving distance 't'. It is maintained as far apart as the suction port 110 and the discharge port 120 is maintained in communication with each other.

Next, the operation and effects of the brake traction control system equipped with the reciprocating hydraulic valve 60 configured as described above will be described.

When the driver steps on the brake pedal 10 while the vehicle equipped with the brake traction control system is running, braking hydraulic pressure is generated in the master cylinder 12 to the hydraulic brake 20 through the NO solenoid valve 30. Is delivered and braked.

At this time, a part of the braking hydraulic pressure is also transmitted to the inside of the reciprocating hydraulic valve 60 through the suction port 110. When the braking hydraulic pressure of 4 bar or more is transmitted upward from the lower surface of the valve member 65, the return spring 68 is applied. The plunger 64 slides upward by a distance of 't' while winning the force of. As the plunger 64 gradually rises, the sealing portion 652 of the valve member 65 comes into close contact with the step surface 63. As a result, as shown in FIG. 5, communication between the suction port 110 and the discharge port 120 is blocked, so that the braking hydraulic pressure is transmitted only to the hydraulic brake 20 side.

And if the ECU (not shown) detects the wheel lock (WHEEL LOCK) by the electrical signal input from the wheel sensor (not shown) and ABS control is required, the NO type solenoid valve 30 and the NC type solenoid valve (31). ) To reduce the brake hydraulic pressure. That is, the NC type solenoid valve 31 is opened to release the braking hydraulic pressure, which is temporarily stored in the low pressure accumulator 40. When the braking hydraulic pressure of the hydraulic brake 20 is reduced or increased to an optimal state, the ECU (not shown) operates the NO type solenoid valve 30 to maintain the braking hydraulic pressure of the hydraulic brake 20 as it is. At this time, since the driving current does not flow to the NC type solenoid valve 31, the flow path of the low pressure accumulator 40 is cut off. In addition, when the pressure boosting of the hydraulic brake 20 is required, the ECU (not shown) interrupts the current supply of the NO solenoid valve 30 and simultaneously drives the motor 41 to brake according to the operation of the pump 42. Hydraulic pressure is generated and causes it to act on the hydraulic brake 20 to increase the hydraulic pressure.

And when the driver takes off the brake pedal 10, all the solenoid valves (30, 31) is in the initial condition. In addition, since the braking hydraulic pressure is not transmitted to the reciprocating hydraulic valve 60, the sealing member is lowered downward by the elastic force of the return spring 68 until the center of the valve member 65 contacts the upper end of the support part 661. 652 is dropped again, the suction port 110 and the discharge port 120 is in communication again to the initial state.

On the other hand, if the driver makes a quick start while stepping on the acceleration pedal (not shown) in slippery road conditions, a momentary difference occurs between the vehicle speed and the wheel speed, which is detected by the ECU through the wheel sensor. In other words, slippage occurs when the acceleration pedal is pressed when the vehicle starts on a frozen road or gravel road. When such a situation is detected by the ECU through the wheel sensor, the motor 41 is immediately driven.

Therefore, the oil is pumped under pressure in accordance with the pumping operation of the pump 42, and is delivered to the hydraulic brake 20 side through the high pressure accumulator 43 and the NO solenoid valve 30 to act as a braking hydraulic pressure. As a result, when the driver starts the vehicle while stepping on the acceleration pedal, the lock is applied to the wheel even when the driver does not step on the brake pedal 10, and thus the vehicle starts slowly and safely even under a slip condition.

At this time, since the power is applied to the separate TC solenoid valve 70 provided in the hydraulic line connecting the high pressure accumulator 43 and the master cylinder 12 side, the oil pressure due to the operation of the pump 42 It is transmitted to the hydraulic brake 20 side.

In addition, since the reciprocating hydraulic valve 60 is kept open so that the suction port 612 and the discharge port 613 communicate with each other when the brake pedal 10 is not stepped on, the outlet side of the master cylinder 12 and The oil supply is smoothly supplied to the pump 42 through the hydraulic line 50 connecting the inlet side of the pump 42 to the catching portion 662 of the filter member 66 provided on the lower surface of the valve housing 61. This prevents the ingress of foreign objects.

The operation of the brake traction control system has been described by taking the vehicle as an example, and this operation is performed even when driving under the acceleration pedal on a gravel road or a muddy road.

The oil supply to the pump 42 side during the operation of the brake traction control system is smooth because the reciprocating hydraulic valve 60 according to the present invention is kept open. That is, since the return spring 68 elastically supports the plunger 64 provided with the valve member 65 in the downward direction, the suction port 110 except for the case where the braking hydraulic pressure is transmitted through the suction port 110. ) And the discharge port 120 are in communication with each other to form an oil supply passage to the pump 42 side.

As described above, the reciprocating hydraulic valve 60 forming the oil supply passage reciprocates up and down to open and close the discharge port 120 in the valve housing 61 and the plunger having the valve member 65 coupled to the front end thereof. The 64 is compactly embedded in a state supported by the return spring 68, and the valve housing 61 is fitted into and coupled to the bore 130 of the modulator block 100, thereby making the overall structure compact.

In addition, the plunger 64 provided with the valve member 65 in the valve housing 61, the return spring 68 for restoring the rest, and the filter member 66 in which the support part 661 is integrally formed to limit the downward movement thereof. ) And the like are compactly built, and such a valve housing 61 is fitted to the bore 130 so that assembly thereof can be easily performed.

As described in detail above, the reciprocating hydraulic valve of the brake traction control system according to the present invention is provided with a valve member made of rubber material in the plunger head portion embedded in the valve housing, the discharge port and the suction port according to the vertical movement of the plunger Communication is directly controlled.

Since the plunger is compactly embedded in the valve housing, the manufacturing cost of the reciprocating hydraulic valve as a whole is reduced as well as the assembly is improved.

Claims (2)

A cylinder composed of a large diameter portion 622 and a small diameter portion 621 therein to be coupled to the bore 130 processed by the modulator block 100 and coupled to the suction port 110 associated with the discharge side of the master cylinder 12. A perforation is performed such that the suction port 110 and the discharge port 120 associated with the inlet side of the pump 42 are connected to the valve housing 61 having the 62 and the small diameter portion 621 of the valve housing 61. Discharge hole 623 is located in the large diameter portion 622 of the valve housing 61, when the braking hydraulic pressure is transmitted through the suction port 110, the sealing portion 652 provided at the upper end of the large diameter portion 622 ) And a valve member 65 which is in close contact with the stepped surface 63 of the boundary surface of the small diameter portion 621 and elastically biased upward through an operating spring 67 to close the discharge hole 623. The valve member 65 is fitted and coupled, and the valve member 65 is coupled to the vertical movement of the cylinder 62 in a vertical direction. The plunger 64 is provided above the plunger 64, and when the braking hydraulic pressure is not transmitted through the suction port 110, the sealing part 651 of the valve member 65 is formed at the step surface 63. When the discharge hole 623 is opened by the elastic force of the return spring 68 and the elastic spring of the return spring 68 to bias the plunger 64 in the downward direction so that the oil through the discharge hole 623 Reciprocating hydraulic valve of the brake traction control system, characterized in that it comprises a stepped portion (641) is provided to reduce the diameter on the outer peripheral surface of the head portion of the plunger (64) so as to allow a sufficient discharge. The method of claim 1, The closed upper surface of the valve housing 61 has an air hole 612 in communication with the outside, Reciprocating hydraulic valve of the brake traction control system, characterized in that the plate-shaped dust cover (69) covering the upper surface of the valve housing (61) is provided to prevent foreign matters from entering through the air hole (612).