KR101418326B1 - Master cylinder for brake system - Google Patents

Abstract

A master cylinder for a brake system is disclosed. According to an embodiment of the present invention, there is provided a cylinder bore comprising: a cylinder body having first and second bores formed therein; first and second pistons provided to move forward and backward in the first and second bores; And a second oil inflow port for supplying the oil to the first hydraulic chamber and the second hydraulic chamber, respectively, and a brake master Wherein the first and second bores each have a large diameter portion expanded inside the cylinder body and a reduced diameter portion reduced from the large diameter portion so as to increase the braking initial flow rate, 2 oil inlet port and the first and second hydraulic pressure chambers, respectively, and the first and second oil inlet ports are each provided with a check valve The check valve may be provided with a master cylinder for a brake system which is initially closed when the brake is released and is opened when the pistons return to their original positions after braking.

Description

[0001] The present invention relates to a master cylinder for a brake system,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a master cylinder for a brake system, and more particularly, to a master cylinder for a brake system capable of improving a feeling of control.

In a hydraulic brake system of a vehicle, a master cylinder generates hydraulic pressure and sends it to a caliper brake installed on each wheel.

1 shows a conventional tandem type master cylinder. This master cylinder has a first piston 3 and a second piston 4 provided in advance in the bore 2 of the cylinder body 1 so that the interior of the bore 2 is connected to the second piston 4 (5) and a second hydraulic pressure chamber (6). In this master cylinder, when the first piston 3 advances, the first piston 3 pressurizes the oil in the first hydraulic pressure chamber 5 and the oil pressure in the first hydraulic pressure chamber 5 pressurizes the oil in the second piston 4, . The second piston (4) pressurizes the oil in the second fluid pressure chamber (6). Accordingly, the oil in the first hydraulic chamber 5 is supplied to the caliper brake (not shown) of the two wheels through the first oil discharge hole 7, and the oil in the second hydraulic chamber 6 is supplied to the second oil- (8) to the caliper brakes of the other two wheels.

These master cylinders are used in F / R split (front / rear split) vehicles or X-Split (cross-split) vehicles depending on the manufacturer or type of vehicle. Here, the F / R split vehicle type is a vehicle that controls the braking hydraulic pressure supplied to the current (front wheel) or the rear wheel (rear wheel) of the vehicle, and the X-split vehicle type is one of the left wheel Means a vehicle that controls either the right wheel or the left wheel of the rear wheel. That is, the X-Split type is configured to cross control the four wheels. Recently, X-Split type has been applied to most vehicles. This is because, even if a problem occurs in one of the hydraulic chambers in the process of braking, the braking pressure is formed at the other hydraulic chamber, This is because it has advantages.

On the other hand, a caliper brake installed on each wheel is a device that presses a disk rotating together with the wheel to perform a braking action. At this time, when the roll-back amount is increased in order to reduce the drag of the caliper during the braking operation, the caliper brake has a disadvantage that the initial required amount of fluid is excessive and the initial deceleration is reduced.

In order to solve this problem, a structure for increasing the initial flow rate, for example, a structure for increasing the initial flow rate of the first hydraulic chamber 5, has been proposed. This is because the pressure difference between the two hydraulic chambers 5, It has a problem that it can not be used in an X-split vehicle because it causes a difference in braking force.

The master cylinder has an oil inlet port 9 connected to a reservoir (not shown) in which oil is stored in the cylinder body 1 so that the oil is supplied to each of the fluid pressure chambers 5 and 6. The oil inlet port 9) is merely configured to allow the oil to flow from the reservoir, and the master cylinder proposed to increase the initial flow rate has a problem in that it does not control the flow of oil according to the pressure of the hydraulic pressure chamber, thereby adversely affecting the feeling of the pedal.

It is an object of the present invention to provide a master cylinder for a brake system which can increase the initial flow rate so as to improve the feeling of movement, The purpose is to provide.

It is still another object of the present invention to provide a master cylinder for a brake system that can be applied to an X-split vehicle.

According to an aspect of the present invention, there is provided a cylinder head comprising: a cylinder body having first and second bores formed therein; first and second pistons provided to advance and retreat in the first and second bores; A first oil inflow port for supplying the oil to the first hydraulic pressure chamber and a second oil inflow port for supplying the oil to the second hydraulic pressure chamber are connected to the first and second hydraulic pressure chambers respectively pressurized by the first and second pistons, Wherein the first and second bores each have a large diameter portion expanded inwardly of the cylinder body and a reduced diameter portion reduced from the large diameter portion so as to increase the initial braking flow rate, The main body is provided with first and second oil inflow ports communicating the first and second oil inflow ports and the first and second hydraulic pressure chambers respectively, A check valve is provided to control the flow, and the check valve may be provided with a master cylinder for the brake system, which is initially closed when the brake is released and the pistons are opened when the pistons return to their original positions after braking.

The check valve may include a foret valve having a cylindrical shape passing through the center and having a first opening / closing part for opening / closing the oil inlet at a lower side so as to be movable in the oil inlet port. A valve piston slidably coupled to the for valve valve and having a second opening / closing portion for opening / closing a through hole formed at the center of the for valve valve; A retainer provided on the oil inlet port to be spaced apart from the foret valve; A first elastic member provided between the retainer and the fork valve to press the for valve valve toward the oil inlet; And a second elastic member installed between the oil inlet and the valve piston to press the valve piston toward the for valve valve.

In addition, each of the oil inflow ports may be formed with a first step portion that is in contact with the first opening / closing portion of the for valve valve and a second step portion that supports the second elastic member.

In addition, at least one engaging portion extending downwardly is formed below the for valve valve, and a coupling hole may be formed in the valve piston such that the engaging portion is fitted into a position corresponding to the engaging portion.

In addition, a stopper may be formed at the lower end of the coupling portion to prevent the valve piston from coming off and to limit the movement distance of the valve piston.

Further, the forklift valve may include a flange portion having an upper outer circumferential surface extending outwardly from the first opening and closing portion, and the flange portion may be provided with an oil passage formed at a predetermined interval along the outer circumferential surface so as to allow oil to pass therethrough.

A stepped first spring supporting step for supporting the first elastic member may be formed on the upper part of the for valve valve.

In addition, a stepped second spring supporting step for supporting the second elastic member may be formed on the lower side of the valve piston.

The first elastic member may be configured to have a greater elastic force than the elastic force of the second elastic member.

Further, the retainer may further include a snap ring fixed to the oil inflow port so that the retainer does not move.

The first fluid pressure chamber is divided into a first large hydraulic chamber formed at a position of a large diameter portion of the first bore and a first small hydraulic chamber formed at a position of a small diameter portion of the first bore, A second large hydraulic chamber formed at a position of a large diameter portion of the second bore and a second small hydraulic chamber formed at a position of a small diameter portion of the second bore.

The first piston is formed to have two different cross sectional areas corresponding to the large diameter portion and the small diameter portion of the first bore, so that the first large piston and the first small hydraulic chamber, which press the first large hydraulic chamber, The second large piston being formed to have two different cross sectional areas corresponding to the large diameter portion and the small diameter portion of the second bore and to press the second large hydraulic chamber; And a second small piston which pressurizes the second small hydraulic chamber.

The first and second small pistons may be formed with first and second piston holes so that the oil pressurized from the first and second large hydraulic chambers is introduced into the first and second small hydraulic chambers.

A sealing member is provided between the inner surface of each of the bores and the outer surfaces of the pistons, and the first and second pistons are moved and the first and second piston holes The hydraulic pressure in the large hydraulic pressure chamber is discharged through the first and second piston holes and the check valve is closed, and when the first and second piston holes pass through the sealing member, the pressure difference between each small hydraulic chamber and each large hydraulic chamber And the check valve can be made to open.

The first and second oil inlets may be formed at positions where the first and second large hydraulic chambers are provided, respectively.

The cylinder body may include a first cylinder having a first bore formed therein and a second cylinder having a second bore formed therein, and the first and second cylinders may be coupled by a fastening member.

The master cylinder for the brake system according to the present embodiment can increase the initial flow rate of the first hydraulic pressure type and the second hydraulic pressure chamber to improve the feeling of braking. In addition, a check valve for controlling the bidirectional flow of oil is provided in the oil inflow port through which oil is supplied to each fluid pressure chamber, whereby the feeling of the pedal can be improved by controlling the pressure. Accordingly, the pressure difference between the first and second hydraulic chambers can be eliminated and applied to an X-split vehicle.

Meanwhile, since the first cylinder and the second cylinder are provided so as to be fastenable, the assembling of the pistons having a multi-stage structure can be facilitated.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be described in detail with reference to the following drawings, which illustrate preferred embodiments of the present invention, and thus the technical idea of the present invention should not be construed as being limited thereto.
1 is a sectional view of a master cylinder for a conventional brake system.
2 is a sectional view showing a master cylinder for a brake system according to a preferred embodiment of the present invention.
3 is a view showing a check valve provided in a master cylinder for a brake system according to a preferred embodiment of the present invention;
4 is a plan view showing a fork valve provided in the check valve of FIG. 3 (a perspective view).
5 is a view showing an operating state according to a braking action of a master cylinder for a brake system according to a preferred embodiment of the present invention.
6 is a view showing an operation state of the check valve according to the braking action of the master cylinder in Fig.
FIG. 7 is a view showing an operational state of a check valve according to a returning of pistons to an original position after completion of a braking operation of a master cylinder for a brake system according to a preferred embodiment of the present invention; FIG.

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

2, a master cylinder for a brake system according to the present embodiment includes a first cylinder 13 having a first bore 11 formed therein and a second cylinder 13 having a second bore 12 formed therein And a first piston 21 and a second piston 22 provided in the bores 11 and 12 of the cylinder body 10 so as to be movable forward and backward.

The first cylinder 13 and the second cylinder 14 may be coupled by separate fastening members (not shown). For example, bolts and nuts can be used as the fastening members. Although not shown, fastening holes are formed to facilitate fastening of the bolts and nuts from the outer circumferential surfaces of the portions where the first cylinder 13 and the second cylinder 14 are in contact with each other A flange can be formed. The master cylinder according to the present embodiment is not limited to the engagement of the first and second cylinders 13 and 14 by such a fastening member. Alternatively, the master cylinder according to the present embodiment may be formed by a laser welding or a press- (13, 14).

The first cylinder 13 and the second cylinder 14, which are coupled by various coupling methods as described above, are coupled to each other such that the first and second bores 11 and 12 communicate with each other.

The first and second bores 11 and 12 include large diameter portions 11a and 12a extended to the inside of the first and second cylinders 13 and 14 so as to increase the initial braking flow rate, Diameter portions 11b and 12b whose diameters are reduced from the outer diameter portions 12a and 12a. The first and second pistons 21 and 22 have two different cross sectional areas corresponding to the large diameter portions 11a and 12a and the small diameter portions 11b and 12b of the first and second bores 11 and 12 . The structure of the first and second pistons 21 and 22 will be described below again.

On the other hand, first and second sealing members 25 and 26 are provided between the inner surface of the first bore 11 and the outer surface of the first piston 21, respectively, and the inner surface of the second bore 12, Third and fourth sealing members 27 and 28 are provided between the outer surfaces of the first and second sealing members 22 and 22, respectively. The first and third sealing members 25 and 27 are provided on the large diameter portions 11a and 12a and the second and fourth sealing members 26 and 28 are provided on the small diameter portions 11b and 12b Respectively. Each of the sealing members 25, 26, 27, 28 is accommodated in the support grooves 29 formed in the inner surfaces of the bores 11, 12 so as not to move even when the pistons 21, 22 move back and forth. The internal space of the first bore 11 between the first piston 21 and the second piston 22 is formed by the first hydraulic pressure chamber 31 and the second piston 22 and the second bore 12 by the second bore 11. [ The inner space between the inner end surfaces of the first and second hydraulic chambers 32, 32 is formed by the second hydraulic chamber 32.

The first hydraulic chamber 31 has a first large hydraulic chamber 31a formed at a position of the large diameter portion 11a of the first bore 11 and a second large hydraulic pressure chamber 31b formed at a position of the small diameter portion 11b of the first bore 11 And a first small hydraulic chamber 31b formed therein. Similarly, the second hydraulic chamber 32 has a second large hydraulic chamber 32a formed at a position of the large-diameter portion 12a of the second bore 12 and a second large- And a second small hydraulic pressure chamber 32b formed in the second small hydraulic pressure chamber 32b. The first and second pistons 21 and 22 for pressing the first and second fluid pressure chambers 31 and 32 have a stepped shape corresponding to the first and second bores 11 and 12 as described above .

More specifically, the first piston 21 includes a first large piston 21a extended to pressurize the first large hydraulic chamber 31a, a first small piston 21b pressurizing the first small hydraulic chamber 31b, ). The first large piston 21a and the first small piston 21b are integrally formed and operated together. The second piston 22 has a second large piston 22a extended to press the second large hydraulic chamber 32a and a second small piston 22b pressing the second small hydraulic chamber 32b Respectively. The first and second pistons 21 and 22 have a stepped two-step shape so that the master cylinder is divided into first and second cylinders 13 and 14 at the time of manufacture.

The structure in which the first fluid pressure chamber 31 and the second fluid pressure chamber 32 are operated by the first and second pistons 21 and 22 will be described below.

When the first and second hydraulic pressure chambers 31 and 32 are pressed by the first and second pistons 21 and 22 to the cylinder body 10, the oil in the first and second hydraulic pressure chambers 31 and 32 A first oil discharge hole 33 is formed in the first fluid pressure chamber 31 side and a second oil discharge hole 34 is formed in the second fluid pressure chamber 32 side. Accordingly, when the first piston 21 advances, the first piston 21 presses the first hydraulic chamber 31, the pressure of the first hydraulic chamber 31 pressurizes the second piston 22, The oil in the first and second hydraulic pressure chambers 31 and 32 is discharged to the first and second oil discharge holes 33 and 34, respectively, And supplied to the caliper brake (not shown) on each wheel side.

The first small pressure chamber 31b of the first hydraulic pressure chamber 31 is provided with a first restoring spring 35 for restoring the first piston 21 after the end of the braking operation and the second hydraulic pressure chamber 32, A second restoring spring 36 for restoring the second piston 22 is also installed in the second small hydraulic pressure chamber 32b. The first and second small pistons 21b and 22b of the first and second pistons 21 and 22 are forwardly pivoted to the inside so that the first and second restoring springs 35 and 36 can enter into the inside of the first and second small pistons 21b and 22b, The spring receiving grooves 37 and 38 are formed. The first and second retainers 39 and 40 for supporting the restoring springs 35 and 36 can be installed in the spring receiving grooves 37 and 38 of the first and second small pistons 21 and 22, And a first support portion 41 and a second support portion 42 in the form of a rod extending forward from the inside are provided. The first and second support portions 41 and 42 are provided with snap rings 43 and 44 for preventing separation of the first and second retainers 39 and 40, respectively. That is, the first and second restoring springs 35 and 36 have one end supported in the spring receiving grooves 37 and 38 and the other end supported at the flange-shaped ends 39a and 40a of the first and second retainers 39 and 40 . The first and second retainers 39 and 40 are retractably fitted on the outer surfaces of the first and second support portions 41 and 42 and retaining rings 43 and 43 that are fastened to the first and second support portions 41 and 42 , 44).

First and second oil inflow ports 51 and 52 connected to a reservoir (not shown) in which oil is stored are provided on the upper portion of the cylinder body 10, that is, the upper portions of the first and second cylinders 13 and 14 , And these oil inflow ports 51 and 52 communicate with the first and second hydraulic pressure chambers 31 and 32 through the first and second oil inflow ports 53 and 54, respectively. The first oil inlet 53 is formed between the first sealing member 25 and the second sealing member 26 and the second oil inlet 54 is formed between the third sealing member 27 and the fourth sealing member 26. [ Is formed between the sealing members (28). Specifically, the first and second oil inflow ports 53 and 54 are formed at the positions where the first and second large hydraulic chambers 31a and 32a are formed, respectively, to communicate with the first and second large hydraulic chambers 31a and 32a, do. The oil introduced into the first and second small pistons 21b and 22b through the first and second oil inflow ports 53 and 54 is supplied to the first and second large pressure chambers 31a and 32a through the first and second large pressure chambers 31a and 32a. The first and second piston holes 23 and 24 are formed to communicate with the outer surfaces of the spring receiving grooves 37 and 38 so as to be introduced into the second small hydraulic pressure chambers 31b and 32b. At this time, each of the oil inflow ports 53 and 54 has a stepped step portion whose outer diameter decreases from the upper portion to the lower portion. That is, each of the oil inflow ports 53 and 54 includes first stepped portions 53a and 54a which are in contact with a first opening / closing portion (see 113 'in FIG. 3) of a forgat valve And second stepped portions 53b and 54b for supporting a second elastic member (refer to '150' in FIG. 3) to be described later. The oil inlets 53 and 54 will be described below again.

The first and second piston holes 23 and 24 are formed such that the first and second oil inflow ports 53 and 54 are connected to the first and second hydraulic pressure chambers 21 and 22 when the first and second pistons 21 and 22 are retracted, 32 and the second and fourth sealing members 26, 28, respectively. This configuration allows the oil to flow through the first and second piston holes 23, 24 when the first and second pistons 21, 22 are retracted, and the first and second pistons 21, The first and second piston holes 23 and 24 are moved outwardly from the positions of the second and fourth sealing members 26 and 28 to move the oil through the first and second piston holes 23 and 24 So that the flow is blocked. Therefore, when the first and second pistons 21, 22 are retracted, the oil can be replenished to the first and second hydraulic pressure chambers 31, 32, and the first and second pistons 21, The first and second fluid pressure chambers 31 and 32 can be pressed by the first and second pistons 21 and 22, respectively.

In the meantime, reference numeral 55 ', which is not shown, is provided between the reservoir (not shown) and the oil inflow ports 51 and 52 which are installed in the oil inflow ports 51 and 52 and connected to the oil inflow ports 51 and 52, It is a seal to prevent the oil from leaking.

According to one embodiment of the present invention, the first and second oil inlet ports 51 and 52 are respectively provided with check valves 100 for controlling the bidirectional flow of the oil. The check valve 100 is initially closed for braking and is made such that, after braking, the pistons 21, 22 open upon return to their original position. For example, the check valve 100 is initially closed and the hydraulic pressure in the first and second large hydraulic chambers 31a and 32a is transmitted to the first and second small holes 23 and 24 through the first and second piston holes 23 and 24, And then is transmitted to the hydraulic chambers 31b and 32b and then opened. This allows the oil in the first and second large hydraulic chambers 31a and 32a to be discharged to the first and second oil discharge holes 33 and 34 through the first and second small hydraulic chambers 31b and 32b, (Not shown) to increase the flow rate of the oil. As a result, the flow rate of the oil at the initial stage of the braking operation is increased, thereby improving the damping sensation.

The check valve 100 will be described in more detail with reference to FIG.

3, the check valve 100 is installed in the first and second oil inflow ports 51 and 52 to control the bidirectional oil flow between the reservoir (not shown) and the respective fluid pressure chambers 31 and 32 . The check valve 100 includes a cylindrical valve body 110 having a through hole 111 formed at the center thereof so as to be movable forward and backward in the oil inlet ports 51 and 52, A first elastic member 140 and a valve piston 120 for pushing the forgot valve 110 toward the oil inflow ports 53 and 54 toward the fore valve 110 And a second elastic member (150) for pressing the second elastic member (150). The check valve 100 provided in the first oil inflow port 51 and the second oil inflow port 52 are the same as those of the first oil inflow port 51 and the second oil inflow port 52, 51, respectively.

A first opening and closing part 113 for opening and closing the first oil inlet 53 and a stepped first spring supporting step 114 for supporting the first elastic member 140 on the upper side are provided on the lower valve 110, Is formed. A lower portion of the forgot valve 110 is provided with an engaging portion 112 extending downward and a flange portion 116 having an upper outer peripheral surface of the forget valve 110 extended outward.

More specifically, the first opening and closing part 113 is provided on the lower outer surface of the forgot valve 110 and is in close contact with the first stepped part 53a of the first oil inflow port 53 to open and close the first oil inflow port 53, . Therefore, the forklift valve 110 is preferably made of a rubber material having elasticity, and only the first opening and closing part 113 which is in close contact with the first step part 53a may be made of a rubber material.

The first spring support step 114 protrudes upward along the edge of the through hole 111 of the for valve valve 110. The first spring support step 114 supports the lower end of the first elastic member 140, as shown in the figure.

The engaging portion 112 is formed in the vicinity of the edge of the lower through hole 111 of the for valve valve 110 with a bar shape. The engaging portions 112 are formed in a radial direction with respect to the through holes 111, and are formed at least at two or more intervals. The engagement portion 112 has a predetermined length as a portion to be engaged with the valve piston 120. At this time, the length of the engaging portion 112 is set such that the valve piston 120 moves in the longitudinal direction of the engaging portion 112 and the valve piston 120 does not come in contact with the first oil inlet 53, And means a length enough to open and close the through-hole 111. A stopper 118 is provided at the lower end of the fork valve 110 to restrict the movement distance of the valve piston 120.

The flange portion 116 is formed so that the upper outer circumferential surface of the forgot valve 110 extends toward the inner circumferential surface of the first oil inflow port 51. At this time, as shown in FIG. 4, the flange portion 116 is formed with oil passages 117 which are vertically spaced apart from each other by a predetermined distance along the outer circumferential surface. The oil passage 117 is formed so as to allow oil to pass therethrough, and the number thereof can be selectively increased or decreased.

The valve piston 120 is provided with a second opening and closing part 121 for opening and closing the through hole 111 of the fork valve 110 on the upper side and a stepped second spring for supporting the second elastic member 150 on the lower side, A support jaw 125 is formed. The valve piston 120 is slidably engaged with the fork valve 110 as described above. The valve piston 120 is formed with a coupling hole 122 so that the coupling portion 112 is fitted in the position corresponding to the coupling portion 112.

The second opening and closing part 121 is provided at the center of the upper side of the valve piston 120 and protrudes upward to have a semicircular shape. The second opening and closing part 121 is in close contact with the through hole 111 to open and close the through hole 111. Accordingly, the valve piston 120 is preferably made of a rubber material having elasticity, and only the second opening and closing part 121 which is in close contact with the through hole 111 may be made of a rubber material.

The second spring supporting step 125 protrudes downward to support the upper end of the second elastic member 150. The second spring support protrusion 125 is formed in the outer side of the vicinity of the coupling hole 122 so as not to interfere with the coupling portion 112 of the for valve valve 110 when the valve piston 120 moves.

Meanwhile, a retainer 130 for supporting the first elastic member 140 for pressing the forett valve 110 toward the first oil inlet 53 is provided. The retainer 130 is press-fitted into the first oil inflow port 51 at a predetermined distance above the for valve valve 110 to support the upper end of the first elastic member 140. At this time, a retaining ring 135 is provided on the upper end of the retainer 130 in order to maintain the retained state of the retainer 130 in the first oil inflow port 51. The upper end of the first elastic member 140 is supported by the retainer 130 and the lower end of the first elastic member 140 is supported by the first spring support step 114 of the for valve valve 110 to press the for valve valve 110 downward .

The upper end of the second elastic member 150 is supported by the second spring support step 125 of the valve piston 120 and the lower end of the second elastic member 150 is supported by the second step portion 53b of the first oil inlet 53 So as to press the valve piston 120 upward.

The elastic force of the first elastic member 140 is greater than the elastic force of the second elastic member 150. The first elastic member 140 thus absorbs the elastic force of the second elastic member 150 and presses the forgot valve 110 toward the first oil inlet 53 so that the first opening and closing portion 113 is normally closed by the first oil inlet 53 are closed.

The overall operation of the master cylinder for a brake system as described above will now be described.

First, braking does not occur when the brake pedal (not shown) is depressed during the braking operation, but the braking is started after the brake pedal advances to some extent. That is, the interval between the start of the brake pedal and the start of the braking is referred to as the "Lost Travel" section (hereinafter referred to as "the LT section") and the shorter the LT section is, I feel. That is, if the initial flow rate is increased and the LT section is decreased, the damping sensation is improved.

Accordingly, when the first piston 21 is pressed by the initial braking operation using the master cylinder according to the present embodiment, the first piston 21 advances and presses the first hydraulic chamber 31, The second piston 22 is pressurized and advanced by this pressure to which the second fluid pressure chamber 31 is pressed so that the second fluid pressure chamber 32 is pressurized. More specifically, when the first large hydraulic pressure chamber 31a is pressed by the first large piston 21a of the first piston 21, the oil in the first large hydraulic pressure chamber 31a is pressurized by the first piston hydraulic pressure chamber 31a, (Not shown) through the first oil discharge hole 33 after being supplied to the first small hydraulic pressure chamber 31b through the second oil pressure chamber 23 and the first small oil pressure chamber 31b. As the second large hydraulic chamber 32a is pressed by the second large piston 22a of the second piston 22, the oil in the second large hydraulic chamber 32a is pressurized by the second piston hole 22a, 24 to the second small hydraulic chamber 32b, and then supplied to the caliper brake (not shown) through the second oil discharge hole 34. [ As a result, the hydraulic pressure in the first and second large hydraulic chambers 31a and 32a at the initial stage of braking is added and supplied to the caliper brake, thereby increasing the braking hydraulic pressure at the initial braking period.

At this time, the check valve 100 formed in the first and second oil inflow ports 51 and 52 is closed as shown in FIGS. 2 and 3. This is because the oil in the first and second large hydraulic pressure chambers 31a and 32a flows into the first and second small hydraulic pressure chambers 31b and 32b through the first and second piston holes 23 and 24, The pressure is not generated in the first and second flow passages 31 and 32.

The first and second pistons 21 and 22 are moved a predetermined distance and the LT section is formed after the first and second piston holes 23 and 24 formed in the first and second small pistons 21b and 22b, And passes through the second and fourth sealing members 26 and 28 to perform the original master cylinder. 5 and 6, when the first and second pistons 21 and 22 are advanced (moved to the left) and the first and second piston holes 23 and 24 are moved to the second and fourth The first and second small hydraulic pressure chambers 31b and 32b and the first and second large hydraulic pressure chambers 31a and 31b are separated by the second and fourth sealing members 26 and 28 when they pass through the sealing members 26 and 28, 32a are sealed, pressure is generated in the first and second large hydraulic chambers 31a, 32a. Since the pistons 21 and 22 continue to move forward, the oil in the first and second large hydraulic chambers 31a and 32a is supplied to the reservoir (not shown) through the first and second oil inlets 53 and 54, . That is, the oil in the first and second large hydraulic pressure chambers 31a and 32a is pushed upward together with the forgot valve 110 and the valve piston 120 to open the respective oil inlets 53 and 54 so that oil flows to the reservoir side . At this time, when each of the oil inflow ports 53 and 54 is opened, the oil can flow through the oil passage 117 formed in the flange portion 116 of the forget valve 110. By opening the check valves 100 formed in the first and second oil inflow ports 51 and 52, the first and second pistons 21 and 22 are advanced to the first and second large hydraulic chambers The oil in the first and second small hydraulic pressure chambers 31b and 32b is supplied to the caliper brakes 31a and 32a of the respective wheels via the first and second oil discharge holes 33 and 34 Not shown) so that braking can be performed.

Finally, when the braking operation is released, the first and second pistons 21 and 22 are pushed rearward due to the elasticity of the first restoring spring 35 and the second restoring spring 36, so that the first and second pistons 21, 22) are restored to their original state. At this time, as shown in FIG. 7, each check valve 100 is kept open. The oil stored in the reservoir at the time of restoration of the first and second pistons 21 and 22 presses the fore valve 110 and the valve piston 120 at this time, The first valve unit 113 is kept in close contact with the first stepped portion 53a so that the valve piston 120 is moved downward through the through hole 111 of the valve body 110, The opening and closing part 121 opens the through hole 111 and oil is supplied to the respective fluid pressure chambers 31 and 32 via the through hole 111 and the respective oil inlets 53 and 54. [ When the first and second pistons 21 and 22 return to their original positions when oil is replenished to the hydraulic pressure chambers 31 and 32, the check valve 100 is rotated by the first and second elastic members 140 and 150, Is closed.

As a result, the bore (11, 12) is divided into a large-diameter portion and a small-diameter portion so as to increase the initial flow rate, and the flow of oil is controlled by a check valve (100) .

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. It will be understood that various modifications and changes may be made without departing from the scope of the appended claims.

11: first bore 12: second bore
13: first cylinder 14: second cylinder
21: first piston 21a: first large piston
22b: first small piston 22: second piston
22a: second large piston 22b: second small piston
23: first piston hole 24: second piston hole
31: first hydraulic chamber 31a: first hydraulic chamber
31b: first small hydraulic chamber 32: second hydraulic chamber
32a: second large hydraulic chamber 32b: second small hydraulic chamber
33: first oil discharge hole 34: second oil discharge hole
51: first oil inlet port 52: second oil inlet port
53: first oil inlet 54: second oil inlet
100: Check valve 110: For valve valve
111: through hole 112:
113: first opening and closing part 114: first spring supporting chin
116: flange portion 117: oil passage
120: valve piston 121: second opening /
122: engagement hole 125: second spring support chin
130: retainer 135: snap ring
140: first elastic member 150: second elastic member

Claims (16)

A cylinder body having first and second bores formed therein, first and second pistons provided to advance and retreat within the first and second bores, first and second pistons respectively urged by the first and second pistons, And a second oil inflow port for supplying oil to the second fluid pressure chamber. The master cylinder for a brake system according to claim 1,
Wherein the first and second bores each have a large diameter portion expanded toward the inside of the cylinder body and a reduced diameter portion reduced from the large diameter portion so as to increase the braking initial flow rate,
The cylinder body is provided with first and second oil inflow ports communicating the first and second oil inflow ports and the first and second hydraulic pressure chambers respectively,
Wherein the first and second oil inlet ports are each provided with a check valve to control the bidirectional flow of oil,
The check valve
A foret valve having a cylindrical shape passing through the center and being provided so as to be able to move forward and backward in each of the oil inlet ports and provided with a first opening and closing part for opening and closing the oil inlet,
A valve piston slidably coupled to the for valve valve and having a second opening / closing portion for opening / closing a through hole formed at the center of the for valve valve;
A retainer provided on the oil inlet port to be spaced apart from the foret valve;
A first elastic member provided between the retainer and the fork valve to press the for valve valve toward the oil inlet; And
And a second elastic member installed between the oil inlet and the valve piston to press the valve piston toward the for valve valve,
Wherein the check valve is initially closed for braking and is opened when the pistons return to their original positions after braking. delete The method according to claim 1,
Wherein each of the oil inflow ports is formed with a first step portion that is in contact with the first opening and closing portion of the for valve valve and a second step portion that is used to support the second elastic member. The method according to claim 1,
And at least one engaging portion extending downwardly below the for valve valve,
And a coupling hole is formed in the valve piston such that the coupling portion is fitted in a position corresponding to the coupling portion. 5. The method of claim 4,
Wherein a stopper is formed at a lower end of the coupling portion to prevent the valve piston from being separated from the valve piston and to restrict a movement distance of the valve piston. The method according to claim 1,
Wherein the foretat valve includes a flange portion having an upper outer circumferential surface extending outwardly of the first opening and closing portion and an oil passage formed at a predetermined interval along an outer circumferential surface of the flange portion so as to allow oil to pass therethrough. . The method according to claim 1,
And a stepped first spring supporting step for supporting the first elastic member is formed on the upper part of the for valve valve. The method according to claim 1,
And a stepped second spring supporting step for supporting the second elastic member is formed on the lower side of the valve piston. The method according to claim 1,
Wherein the first elastic member is made to have an elastic force greater than the elastic force of the second elastic member. The method according to claim 1,
Further comprising a snap ring fixed to the oil inflow port so that the retainer does not move. The method according to claim 1,
Wherein the first hydraulic chamber is divided into a first large hydraulic chamber formed at a large diameter portion of the first bore and a first small hydraulic chamber formed at a small diameter portion of the first bore,
Wherein the second hydraulic chamber is divided into a second large hydraulic chamber formed at a large diameter portion of the second bore and a second small hydraulic chamber formed at a position of a small diameter portion of the second bore. cylinder. 12. The method of claim 11,
The first piston is formed to have two different cross-sectional areas corresponding to the large-diameter portion and the small-diameter portion of the first bore. The first large piston and the first large-pressure chamber press the first large- 1 small pistons,
The second piston is formed to have two different cross-sectional areas corresponding to the large-diameter portion and the small-diameter portion of the second bore, and is configured to pressurize the second large-diameter piston and the second small- 2 < / RTI > small pistons. 13. The method of claim 12,
Wherein the first and second small pistons are formed with first and second piston holes for allowing the oil pressurized from the first and second large hydraulic chambers to flow into the first and second small hydraulic pressure chambers. Master cylinder. 14. The method of claim 13,
A sealing member is provided between the inner surface of each bore and the outer surface of the pistons,
The hydraulic pressure in the first and second large hydraulic chambers is discharged through the first and second piston holes until the first and second pistons move and before the first and second piston holes pass the sealing member, Wherein the valve is closed, and when the first and second piston holes pass through the sealing member, the space between each of the small hydraulic pressure chambers and each of the large hydraulic pressure chambers is sealed and the check valve is opened. . 12. The method of claim 11,
Wherein the first and second oil inlets are formed at positions where the first and second large hydraulic chambers are respectively provided. The method according to claim 1,
Wherein the cylinder body comprises a first cylinder in which a first bore is formed and a second cylinder in which a second bore is formed, and the first and second cylinders are coupled by a fastening member, .

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