KR20140111409A - Pilot Valve of brake system - Google Patents

Abstract

A pilot valve of a vehicle brake system is disclosed. According to an embodiment of the present invention, the pilot valve of the vehicle brake system may comprise: a cylindrical sleeve provided in an oil inlet passage of a low-pressure accumulator; a valve seat which is coupled to the lower part of the sleeve, and has a seat surface on a hollow interior; a plunger which is provided on the inner sleeve to be able to be lifted, has a center hole to form a first opening and closing passage therein, and forms the seat surface and a second opening and closing passage on the outside; a ball valve disposed in the interior of the plunger to be in contact with the center hole; a first spring for elastically pressurizing the ball valve; a second spring provided between the valve seat and the plunger; and a valve pin which is provided on a piston of the low-pressure accumulator to be in contact with the ball valve.

Description

[0001] The present invention relates to a pilot valve for a vehicle brake system,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pilot valve of a vehicle brake system, and more particularly, to a pilot valve applied to a vehicle brake system such as ABS, TCS, ESC, and the like.

Generally, a vehicle includes a plurality of wheel brakes including a caliper device having a disk and a pair of pads for braking front and rear wheels for deceleration or stoppage while the vehicle is running, and a booster And a master cylinder. When the driver depresses the brake pedal, the hydraulic pressure generated by the booster and the master cylinder is transmitted to the pad of the wheel brake, and the pad presses the disk to generate the braking force. However, if the braking pressure is greater than the road surface state while the driver depresses the brake pedal to increase or maintain the braking force, or if the frictional force of the wheel brake generated by the braking pressure is greater than the braking force generated on the tire or the road surface, Slip phenomenon occurs.

In recent years, an anti-lock brake system (ABS: Anti-Lock Brake System) that prevents slippage of the wheel during braking to effectively prevent the slip phenomenon and to exhibit a strong and stable braking force and to facilitate the driving operation, A traction control system (TCS: Traction Control System) that prevents excessive slip of a wheel during a sudden acceleration or a sudden acceleration, and an anti-lock brake system and traction when the vehicle is not adjusted to the driver's will by force externally applied A brake system having a vehicle posture control system (ESC, VDC) function for stably maintaining the running state of the vehicle by controlling the brakes by combining the controls has been developed.

Various conventional vehicle brake systems as described above are provided with a modulator block (Hydraulic Unit) in which a plurality of electromagnetic opening / closing valves, an accumulator, a motor, and a pump are mounted to control the braking hydraulic pressure transmitted between the master cylinder and the wheel brake, And an electronic control unit (ECU) for controlling them. The electronic control unit senses the vehicle speed through each wheel sensor disposed on the front wheel and the rear wheel, thereby controlling the operation of each valve, the motor, and the pump.

Japanese Patent Application Laid-Open No. 2000-142346 (May 23, 2000) This document discloses a regulating reservoir including a pilot valve as an example of a valve provided in a modulator block and a vehicle brake apparatus using the same. The pilot valve consists of a ball, a shaft, a valve seat, a spring, and the shaft selectively contacts the ball to control the flow of the brake fluid. However, the pilot valve has a narrow flow path area in which the ball is opened and closed, so that it is not easy to quickly control the fluid due to the braking operation.

The pilot valve of the vehicular brake system according to the embodiment of the present invention expands the flow passage area through which the fluid passes, thereby enabling rapid control of the fluid according to the braking operation.

A pilot valve of a vehicle brake system according to one aspect of the present invention includes a cylindrical sleeve provided in an oil inflow passage of a low pressure accumulator, a valve seat coupled to a lower portion of the sleeve and having a seat surface in an inner hollow, A plunger having a center hole for forming a first opening / closing flow path therein and forming a seat surface and a second opening / closing flow path on the outside, a ball valve provided inside the plunger to contact the center hole, A second spring provided between the valve seat and the plunger, and a valve pin provided in the piston of the low pressure accumulator and in contact with the ball valve.

The plunger may include a plurality of projecting pieces spaced from each other along the circumferential direction so as to form an outer flow path and support one side of the second spring.

Further, the second spring may be provided to have an elastic force for separating the plunger from the valve seat.

The elastic force of the first spring may be greater than the elastic force of the second spring.

The sleeve may include a sleeve cap coupled to an upper end of the sleeve cap. The sleeve cap may be provided in a bar or triangle shape and may be secured to the sleeve while fluid may pass through the sleeve through the oil inlet passage. have.

The low pressure accumulator may further include a fluid storage chamber and a piston that moves up and down in the fluid storage chamber, and the valve pin may be integrally formed with the piston.

In addition, the piston may include a spacer protrusion that separates from the upper surface of the fluid storage chamber when the piston is lifted.

The pilot valve of the vehicle brake system according to the embodiment of the present invention provides two internal flow paths through which the brake fluid is moved so that the brake fluid can be rapidly moved according to the braking operation.

Further, the pilot valve of the brake system for a vehicle according to the embodiment of the present invention may be provided with a protrusion on the upper part of the piston provided in the fluid storage chamber of the low-pressure accumulator to sufficiently secure the flow rate space so as to stabilize the flow rate of the fluid flowing into the pump have.

1 is a schematic view of a hydraulic circuit of a vehicle brake system in which a pilot valve according to an embodiment of the present invention is used.
FIG. 2 is a cross-sectional view showing a state in which an inner flow path is closed in a pilot valve of a vehicle brake system according to an embodiment of the present invention. FIG.
3 is a plan view of a pilot valve of a vehicle brake system according to an embodiment of the present invention.
4 is a sectional view showing a state in which the first opening and closing flow path is opened in a pilot valve of a vehicle brake system according to an embodiment of the present invention.
5 is a sectional view showing a state in which the first opening / closing flow path and the second opening / closing flow path are opened in the pilot valve of the vehicular brake system according to the embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Hereinafter, the embodiments described below are provided as examples so that those skilled in the art will be able to fully understand the spirit of the present invention. Accordingly, the present invention is not limited to the embodiments described below and may be embodied in other forms. Further, in order to clearly illustrate the present invention, parts not related to the description are omitted from the drawings, , Length, thickness, etc. may be exaggerated for convenience. Like reference numerals designate like elements throughout the specification.

1 is a schematic view of a vehicle brake system in which a pilot valve according to an embodiment of the present invention is used. Referring to the drawings, a vehicular brake system according to the present embodiment includes a brake pedal 1, a booster 2 for amplifying and outputting the pressing force of the brake pedal 1, And a hydraulic circuit that is connected to the master cylinder 3 and transmits braking hydraulic pressure to each wheel brake 4. The hydraulic circuit is provided in a modulator block (not shown). The wheel brake 4 includes a disk mounted on a wheel of the vehicle, a pad located on both sides of the disk, and a cylinder for pressing the pad by braking hydraulic pressure And a piston for moving back and forth.

Here, the hydraulic circuit is a vehicle control system capable of controlling an anti-lock brake system (ABS) and a traction control system (TCS) System (Electronic Stability Control: ESC) is exemplified, but the present invention is not limited thereto.

In general, the master cylinder 3 is provided with two primary and secondary ports for respectively controlling two wheel brakes FR, FL, RR and RL, And hydraulic circuits 10A and 10B. Since the configuration of the secondary hydraulic circuit 10B is substantially the same as the configuration of the primary hydraulic circuit 10A, the primary hydraulic circuit 10A will be mainly described and a repetitive description of the secondary hydraulic circuit will be omitted. However, the pumps 13 provided in the hydraulic circuits 10A and 10B are driven together with a phase difference of 180 degrees by one motor 14.

1, the primary hydraulic circuit 10A includes a plurality of solenoid valves 11 and 12 for controlling the braking hydraulic pressure transmitted to the wheel brake 4 side of the two wheels RL and FR, A pump 13 for sucking and pumping fluid from the brake cylinder 5 or the master cylinder 3 and a low pressure accumulator 16 for temporarily storing the fluid exiting the wheel brake 4 .

A plurality of solenoid valves (11, 12) are connected to the upstream side and the downstream side of the wheel brake (4). The solenoid valve 11 disposed on the upstream side of each wheel brake 4 is a solenoid valve 11 of NO (normally open) type which is kept open in a normal state and a solenoid valve 12 disposed on the downstream side And is an NC (normally closed) type solenoid valve 12 that is maintained in a normally closed state. The opening and closing operations of the solenoid valves 11 and 12 are respectively controlled by an electronic control unit (ECU) (not shown) that senses the vehicle speed through a wheel sensor (not shown) disposed on each wheel side. For example, in the pressure reducing braking, the NO type solenoid valve 11 is closed and the NC type solenoid valve 12 is opened, so that the fluid that has escaped from the wheel brake 4 side is temporarily stored in the low pressure accumulator 16.

The pump 13 is driven by the motor 14 to suck and discharge the fluid stored in the low pressure accumulator 16 to transfer the fluid pressure of the fluid to the wheel brake 4 side or the master cylinder 3 side.

The hydraulic circuit 10A is provided with an NO solenoid valve 15 (hereinafter referred to as TC solenoid valve) for controlling the TCS mode in the main flow path between the master cylinder 3 and the outlet side of the pump 13, Between the master cylinder 3 and the inlet side of the pump 13, there is provided an oil suction flow path for guiding the fluid of the master cylinder 3 to the inlet side of the pump 13 under the TCS mode control.

The TC solenoid valve 15 is kept open during normal operation so that the braking fluid pressure formed in the master cylinder 3 during normal braking through the brake pedal 1 is transmitted to the wheel brake 4 side through the main flow path. Although not shown, a relief passage and a relief valve may be provided between the oil suction passage and the main passage. The relief passage and the relief valve return the brake fluid to the master cylinder 3 when the brake fluid pressure discharged from the pump 13 rises more than necessary in the TCS mode.

The low pressure accumulator 16 is provided with a fluid storage chamber 17 in the form of a cylinder inside as shown in the enlarged view of Figure 2 and the piston 18 is elastically lifted and lowered by the elastic spring 19 . The piston 18 rises when the fluid in the fluid storage chamber 17 exits to the outside and falls when the fluid in the fluid storage chamber 17 flows.

In addition, the piston 18 includes a spacer projection 18a so as to be spaced from the upper surface of the fluid storage chamber 17 when the piston 18 is located at the top dead center. The spacer projection 18a is formed of a plurality of spaced projections to secure a minimum flow rate in the fluid storage chamber 17. [

The pilot valve 20 of the present embodiment is provided on the upper portion of the low pressure accumulator 16 so that the fluid only flows on the inlet side of the pump 13 on the oil suction flow path.

The pilot valve 20 is provided at one side flow path P1 of the pair of flow paths P1 and P2 provided in the modulator block and the low pressure accumulator 16 is provided with two flow paths P1 and P2 ). The oil passage P1 is an oil intake passage connected to the side of the master cylinder 3 with respect to the low pressure accumulator 16 and the oil passage P2 is an oil extraction passage connected to the pump 13 side with respect to the low pressure accumulator 16. [

The pilot valve 20 includes a sleeve 21 coupled to a valve assembly port provided on the oil inlet passage P1, a valve seat 22 coupled to a lower portion of the sleeve 21, A ball valve 25 provided in the center hole of the plunger 24 and a ball valve 25 provided in the low pressure accumulator 16 and operated in accordance with the operation of the piston 18, (Not shown).

The valve seat 22 is coupled to the lower portion of the low pressure accumulator side and the sleeve cap 24 is coupled to the upper portion of the flow path P1 side.

The valve seat 22 has a bottom surface and side walls. The bottom surface is provided with a hollow surface 22a, and the inner surface of the hollow surface is provided with a tapered seat surface 22b. A sleeve 21 is coupled to the inside of the side wall of the valve seat 22 to form an outer wall of the pilot valve. The sleeve cap 23 coupled to the upper end of the sleeve 21 is provided in the shape of a bar or a triangle as shown in Figure 3 and is fixed to the sleeve 21, .

The plunger 24 is provided with a U-shaped cross section so that a center hole 24a is provided at the center of the bottom surface and a plunger seat surface (not shown) which is in contact with the seat surface 22b of the valve seat 22 24b. The valve seat surface 22b and the plunger seat surface 24b selectively contact and separate from each other to form the second opening / closing flow path L2.

A ball valve 25 is provided in the plunger 24. The ball valve 25 is resiliently pressed by the first spring 26 supported on one side of the sleeve cap 23 and brought into contact with the center hole 24a. The center hole 24a is inclined to minimize the contact area with the ball valve 25 and the center hole 24a and the ball valve 25 are selectively in contact with and spaced from each other to form the first opening and closing flow path L1 .

A protruding piece 24c is provided on the plunger 24 opposite to the plunger seat surface 24b. A plurality of protruding pieces 24c are provided so as to be spaced apart from each other along the circumferential direction of the outer circumference. An empty space between the protruding pieces forms an external flow path. Between the protruding piece 24c and the bottom surface of the valve seat 22 A second spring 27 is provided. The second spring 27 has an elastic force to separate the plunger 24 from the seat surface 23b, but normally maintains the closed state by the master cylinder side hydraulic pressure.

The valve pin 28 is fixedly provided on the upper portion of the piston 18 and penetrates through the center hole 24a of the plunger 24 and the hollow 22a of the valve seat 22 while vertically interlocking with the piston And is in contact with the ball valve 25. When the valve pin 28 rises and the ball valve 25 is separated from the center hole 24a, the oil inlet passage P1 and the oil outlet passage P2 are communicated with each other. The valve pin 28 has a pointed attachment to the end that contacts the ball valve 25 for rapid fluid flow.

The operation and effect of the brake system for a vehicle including the pilot valve according to this embodiment will be described below.

2, in the general braking (CBS) mode, the first opening / closing flow path L1 of the pilot valve 20 is closed by the ball valve 25 which is pressed by the first spring 26, And the fluid in the master cylinder 2 can not flow out to the low pressure accumulator 16 since the second opening and closing flow path L2 is closed by the master cylinder side oil pressure which is larger than the second spring 27. [

When a slip phenomenon occurs in a braking operation of a vehicle equipped with this brake system, the electronic control unit performs ABS mode by combining the three modes of the depressurization, the pressure increase, and the pressure maintenance based on the signals inputted from the respective wheel sensors. Each control mode of the ABS is not controlled in the same state to all four wheels (FR, FL, RR, RL) but can be controlled separately according to the road surface condition and the ABS control state. Each control mode will be described step by step through the primary hydraulic circuit 10A.

First, when the braking force is being exerted by the hydraulic pressure generated in the master cylinder 3 by depressing the brake pedal 1 by the user, the braking pressure on the wheel brake 4 associated with the primary hydraulic circuit 10A is changed to the road surface condition The solenoid valve 11 is closed and the NC type solenoid valve 12 is opened to perform the ABS depressurization mode so as to lower the pressure to the appropriate pressure (depressurization mode). Then, the hydraulic pressure (fluid) partially escapes from the wheel brake 4 side and is temporarily stored in the low-pressure accumulator 16, so that the braking pressure of the wheel brake 4 mounted on each wheel is lowered to prevent the slip of the road surface.

The electronic control unit drives the motor 14 to increase the hydraulic pressure of the wheel brake 4 and controls the pump 13 of the primary hydraulic circuit 10A so as to increase the hydraulic pressure of the wheel brake 4. On the other hand, The ABS pressure increasing mode is performed. That is, the fluid stored in the low-pressure accumulator 16 is pressurized through the pump 13 and is transmitted to the wheel brake 4 side through the open-type NO-type solenoid valve 11, thereby increasing the braking pressure. At this time, the pilot valve 20 is opened during the operation of the pump 13, and the hydraulic pressure discharged from the pump of the secondary hydraulic circuit is returned to the master cylinder according to the braking pressure condition or transmitted to the wheel brake side associated with the secondary hydraulic circuit.

The electronic control unit performs the ABS pressure holding mode when it is necessary to maintain the braking pressure at a constant level in order to reach the state where the braking pressure generates the optimum braking force or to prevent the resonance phenomenon of the vehicle. The ABS pressure holding mode eliminates the pressure change in the wheel brake 4, thereby closing the NO-type solenoid valve 11 of the primary hydraulic circuit 10A to block the hydraulic pressure from moving. At this time, the pilot valve 20 is in the open state, and the hydraulic pressure discharged from the pump 13 is transmitted to the master cylinder 3 side, whereby the ABS pressure holding mode is stably performed.

The TCS mode is performed when the electronic control unit senses a slip phenomenon that occurs when the user depresses the accelerator pedal (not shown) when the road surface is slippery and the user depresses the accelerator pedal (not shown). In the TCS mode, the electronic control unit opens the pilot valve 20, closes the TC solenoid valve 15 in the main flow path, and operates the motor 14 and the pump 13 to pump the fluid.

That is, when the TCS mode is performed, the fluid on the master cylinder 3 is sucked into the inlet of the pump 13 through the pilot valve 20 and the low-pressure accumulator 16 of the oil suction passage, Is transmitted to the wheel brake (4) through the main flow path and the opened NO-type solenoid valve (11), and acts as a braking pressure. As a result, even if the driver depresses the accelerator pedal for the quick start, the wheel locks on the wheel even if the driver does not step on the brake pedal 1, so that the vehicle slowly and stably starts even under a slip condition in which the road surface condition is poor.

On the other hand, as described above, the pilot valve 20 selectively opens the flow path between the master cylinder 2 and the low-pressure accumulator 16 in the ABS mode or the TCS mode.

That is, when the pump 13 operates for the braking operation, the fluid in the fluid storage chamber 17 flows out through the flow path P2 and the piston 18 ascends. As a result, the valve 18, which is provided on the upper surface of the piston 18, The valve 28 pushes the ball valve 25 to open the first opening and closing flow path L1 between the ball valve 25 and the center hole 24a of the plunger as shown in Fig. The fluid in the master cylinder 2 flows out from the flow path P1 to the flow path P2 through the first opening and closing flow path L1.

The plunger 24 is caused to flow (rise) by the elastic force of the second spring 27 so that the valve seat surface 22a and the plunger 24 are moved The second open / close flow path L2 between the seat surfaces 24a is opened as shown in Fig.

Since the pilot valve can secure a sufficient fluid flow rate twice or more than the conventional one through the opened first opening / closing flow path L1 and the second opening / closing flow path L2, the brake control performance greatly increases.

On the other hand, when the fluid in the wheel brake side flows into the fluid storage chamber 17 through the fluid P1 or the fluid of the master cylinder or the oil passage P2 to some extent, the piston 18 descends, While the valve pin 28 provided on the upper surface is also lowered, the first opening / closing flow path L1 and the second opening / closing flow path L2 are sequentially closed. If the elastic force of the second spring 27 is larger than the elastic force of the first spring 26, the second opening / closing flow path L2 may be closed by the elastic force of the first spring 26, The pilot valve may not function without being closed or closed later than the opening / closing flow path L1. At this time, the spacer protrusion 18a provided on the upper surface of the piston 18 allows the fluid in the fluid storage chamber 17 to secure a certain amount of the flow amount to a minimum, thereby preventing cavitations generated when the oil passage is opened can do.

1 .. Brake pedal 2 .. Booster
3 .. Master Cylinder 4 .. Wheel Brake
10A, 10B .. Hydraulic circuit 11, 12, 16 .. Solenoid valve
13. Pump 15. Motor
16 .. Low Pressure Accumulator 17 .. Fluid Storage Room
18 .. Piston 19 .. Elastic spring
20 .. Pilot valve 21 .. Sleeve
22 .. Valve seat 23 .. Sleeve cap
24 .. Plunger 25 .. Ball Valve
26. First spring 27. Second spring
28. Valve pin

Claims (7)

A cylindrical sleeve provided in the oil inflow passage of the low pressure accumulator,
A valve seat coupled to a lower portion of the sleeve and having a seat surface in an inner hollow,
A plunger provided in the sleeve so as to be able to move up and down and having a center hole for forming a first opening and closing flow path therein and forming the seat face and a second opening /
A ball valve provided inside the plunger to contact the center hole,
A first spring for elastically pressing the ball valve,
A second spring provided between the valve seat and the plunger,
And a valve pin provided in the piston of the low pressure accumulator and in contact with the ball valve. The method according to claim 1,
Wherein the plunger has a plurality of projecting pieces spaced from one another in a circumferential direction on the outer circumference so as to form an outer flow path and to support one side of the second spring. 3. The method of claim 2,
And the second spring is provided to have an elastic force for separating the plunger from the valve seat. The method according to claim 1,
Wherein the spring force of the first spring is greater than the spring force of the second spring. The method according to claim 1,
The sleeve includes a sleeve cap coupled to the top,
Wherein the sleeve cap is provided in the form of a bar or triangle and is secured to the sleeve while allowing fluid to pass through the sleeve through the oil inlet passage. The method according to claim 1,
The low pressure accumulator further includes a fluid storage chamber and a piston that ascends and descends in the fluid storage chamber,
Wherein the valve pin is integrally provided with the piston. The method according to claim 6,
Wherein the piston comprises a spacer projection to be spaced apart from an upper surface of the fluid storage chamber when the piston is lifted.

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