KR20200107676A - Master cylinder for electric brake system - Google Patents

Abstract

A master cylinder for an electronic brake system is disclosed. The electronic brake system according to an embodiment of the present invention has a compensation chamber in which a compensation piston movable by the hydraulic pressure of a second master chamber is slidably installed in a second master piston to compensate for a hydraulic pressure drop in a first master chamber due to the reaction force of a pedal simulator in a fallback mode in a structure of a master cylinder having the pedal simulator built in the first master chamber, wherein the hydraulic pressure pressurized by the compensation chamber is provided to a first backup passage through a compensation passage.

Description

Master cylinder for electronic brake system {MASTER CYLINDER FOR ELECTRIC BRAKE SYSTEM}

The present invention relates to an electronic brake system, and more particularly, to a master cylinder for an electronic brake system that generates a braking force using an electrical signal corresponding to a displacement of a brake pedal.

In general, a vehicle is essentially equipped with a brake system for performing braking, and various types of brake systems have been proposed for the safety of drivers and passengers.

In the conventional brake system, when the driver presses the brake pedal, a method of supplying hydraulic pressure required for braking to a wheel cylinder using a mechanically connected booster has been mainly used. However, as the demand of the market to implement various braking functions in detail in response to the operating environment of the vehicle is increasing, recently, when the driver presses the brake pedal, the driver's braking will is electrically controlled from a pedal displacement sensor that senses the displacement of the brake pedal. Electronic brake systems and operating methods including a hydraulic pressure supply device for supplying hydraulic pressure required for braking to a wheel cylinder by receiving a signal are widely spread.

In such an electronic brake system and operation method, the driver's brake pedal operation is generated and provided as an electrical signal in the normal operation mode, and based on this, the hydraulic pressure supply device is electrically operated and controlled to form the hydraulic pressure required for braking to the wheel cylinder. Deliver.

As described above, since these electronic brake systems and operating methods are electrically operated and controlled, they can implement complex and various braking actions, but when a technical problem occurs in an electrical component element, the hydraulic pressure required for braking is not stably formed. There is a risk of threatening the safety of passengers. Therefore, the electronic brake system and operation method enters an abnormal operation mode when one component element fails or falls into an uncontrollable state, and in this case, a mechanism in which the driver's brake pedal operation is directly linked to the wheel cylinder is required. That is, in the abnormal operation mode of the electronic brake system and the operation method, the hydraulic pressure required for braking is immediately formed as the driver applies a pedal effort to the brake pedal, and it must be transmitted directly to the wheel cylinder.

EP 2 520 473 A1 (Honda Motor Co., Ltd.) 2012. 11.

The present embodiment is to provide an electronic brake system capable of reducing the number of parts, miniaturization and weight reduction of products, and stably providing braking pressure even in fallback mode.

According to an aspect of the present invention, a first master chamber pressurized by a first master piston moving in connection with an operation of a brake pedal, a second master chamber pressurized by a second master piston, and the first master chamber A master cylinder including a pedal simulator that is interposed between the first master piston and the second master piston to provide a reaction force to the brake pedal, and a controller that receives hydraulic pressure and controls hydraulic pressure transmitted to each of the two wheel cylinders. 1 hydraulic control unit including a hydraulic circuit and a second hydraulic circuit for controlling hydraulic pressure transmitted to the other two wheel cylinders, a first backup passage connecting the first master chamber and the first hydraulic circuit, and the second A second backup passage connecting the master chamber and the second hydraulic circuit, and a hydraulic pressure compensation unit for compensating for a decrease in hydraulic pressure of the first master chamber according to a reaction force of the pedal simulator in a fallback mode, and the hydraulic pressure compensation unit 2 There is provided an electronic brake system configured to provide the hydraulic pressure of the pressurized medium pressurized by a compensation piston provided to move by the pressure of the pressurized medium accommodated in the second master chamber when the master piston advances to the first backup passage. Can be.

In addition, the hydraulic pressure compensation unit includes a compensation chamber provided in the second master piston so that the compensation piston is slidable, and a compensation channel for transferring a pressurized medium pressurized in the compensation chamber to the first backup channel.

In addition, the compensation chamber may be provided in a concave form at the tip of the first master piston, and an open front of the compensation chamber may be sealed by the compensation piston slidable in the compensation chamber.

In addition, the compensation chamber may be provided with a compensation spring that provides an elastic force for pressing the compensation piston forward.

In addition, a sealing member is installed on the outer periphery of the compensation piston, so that the flow of the pressurized medium between the second master chamber and the compensation chamber may be blocked.

In addition, the compensation piston is supported by a locking jaw provided in the compensation chamber, so that it is not separated from the compensation chamber.

In addition, the first master piston may be provided with a compensation hole for communicating the compensation chamber and the compensation flow path.

In addition, the compensation flow path may be provided with a compensation valve for controlling the flow of the pressurized medium in both directions.

In addition, it further comprises a reservoir in which the pressurized medium is stored, and a simulation channel provided with a simulator valve that connects the reservoir and the first master chamber and controls the flow of the pressurized medium.

Further, it further includes a hydraulic pressure supply device for generating hydraulic pressure in response to an electrical signal outputted in response to the displacement of the brake pedal and providing it to the hydraulic control unit.

In the electronic brake system according to an embodiment of the present invention, a pedal simulator is built into the master cylinder to reduce product size and weight, and to supply stable hydraulic pressure in the fallback mode of the electronic brake system.

1 schematically shows an electronic brake system according to an embodiment of the present invention.
2 is a cross-sectional view showing a master cylinder according to an embodiment of the present invention.
3 is an operational state diagram illustrating a state in which braking of the electronic brake system according to an embodiment of the present invention is performed.
4 is a diagram illustrating an operation state of an electronic brake system in a fallback mode according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The embodiments introduced below are provided as examples in order to sufficiently convey the spirit of the present invention to those of ordinary skill in the art. The present invention is not limited to the embodiments described below and may be embodied in other forms. In order to clearly describe the present invention, parts irrelevant to the description are omitted from the drawings, and in the drawings, the width, length, thickness, etc. of the components may be exaggerated for convenience. The same reference numbers throughout the specification denote the same elements.

1 is a schematic diagram of an electronic brake system according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view illustrating a master cylinder according to an embodiment of the present invention.

1 and 2, the electronic brake system according to an embodiment of the present invention pressurizes and discharges the pressurized medium accommodated inside by the reservoir 10 in which the pressurized medium is stored and the pedal force of the brake pedal 20. The master cylinder 100 and a wheel cylinder 30 that performs braking of each wheel (RR, RL, FR, RL) by transmitting the hydraulic pressure of the pressurized medium, and a pedal displacement sensor that detects the displacement of the brake pedal 20 A hydraulic pressure supply device 40 that generates hydraulic pressure of the pressurized medium through mechanical operation by receiving the driver's braking intention as an electrical signal by 21, and a hydraulic control unit that controls the hydraulic pressure transmitted to the wheel cylinder 30 And an electronic control unit (ECU) for controlling the hydraulic pressure supply device 40 and various valves based on the hydraulic pressure information and the pedal displacement information.

The master cylinder 100 has a pedal simulator 110 built in therein, and when the driver applies a foot force to the brake pedal 20 for braking operation, the reaction force is provided to the driver to provide a stable pedal feel and at the same time It is provided to pressurize and discharge the pressurized medium accommodated in the.

The master cylinder 100 includes a cylinder block 101 forming a chamber therein, a first master piston 130 and a second master piston 120 spaced apart in a line inside the cylinder block 101, and a first It includes a pedal simulator 110 interposed between the master piston 130 and the second master piston 120.

The cylinder block 101 has a multi-stage bore formed therein, and the bore formed in the cylinder block 101 is a first master chamber 102 in which a pressurizing medium is compressed by a first master piston 130, and a second It includes a second master chamber 103 in which the pressurized medium is compressed by the master piston 120.

The first master chamber 102 is formed to have a relatively larger diameter than the second master chamber 103, and the pedal simulator 110 is built in the first master chamber 102.

The pedal simulator 110 is provided in a state interposed between the first master piston 130 and the second master piston 120 and provides a pedal feeling to the driver through an elastic restoring force generated during compression.

The pedal simulator 110 includes a rubber member 111 interposed between the first master piston 130 and the second master piston 120, and both ends of the first master piston 130 and the second master piston 120, respectively. It includes a simulator spring 112 supported on.

The simulator spring 112, together with the rubber member 111, provides a feeling of pedaling to the driver and returns the first master piston 130 to its original position when an operation such as braking is released. Here, the pedal simulator 110 may be composed of only the rubber member 111 without the simulator spring 112.

In the first master chamber 102, the pressurized medium can be introduced and discharged through the first backup port 104, and the second master chamber 103 is the pressurized medium through the second backup port 105. Can be.

The first backup port 104 and the second backup port 105 are backup for directly supplying the hydraulic pressure discharged from the master cylinder 100 to the hydraulic control unit 50 when the hydraulic pressure supply device 40 is unable to operate normally. It is connected to the flow paths 60 and 61.

The master spring 115 is disposed in the second master chamber 103, and the master spring 115 is compressed when displacement occurs in the second master piston 120 according to an operation such as braking to store elastic force, and then braking. When the operation of the back is released, the second master piston 120 is returned to its original position by the stored elastic force.

In the first master chamber 102 and the second master chamber 103, a pressurized medium may be introduced and discharged through the first hydraulic port 106 and the second hydraulic port 107 formed in the cylinder block 101.

The first hydraulic port 106 is connected to the first reservoir flow path 11 to allow the flow of the pressurized medium between the first master chamber 102 and the reservoir 10, and the second hydraulic port 107 is 2 It is connected to the reservoir flow path 12 to allow the flow of the pressurized medium between the second master chamber 103 and the reservoir 10.

The first master chamber 102 and the second master chamber 103 communicate with the reservoir 10 when the brake pedal is in a rest state in which the brake pedal is not operated.

The first master chamber 102 communicates with the reservoir 10 through a hole 131 formed in the first master piston 130 when in the resting state, and when the first master piston 130 advances, the first master piston The first master pm 102 and the first hydraulic port 106 are not communicated with each other by the sealing members 132 and 133 installed before and after the 130 and the first hydraulic port 106.

The second master chamber 103 communicates with the reservoir 10 through the hole 121 formed in the second master piston 120 when it is in a resting state, and when the second master piston 120 advances, the second master piston The second master chamber 103 and the second hydraulic port 107 are not communicated with each other by the sealing members 122 and 123 installed before and after the 120 and the second hydraulic port 107.

In the first master chamber 102, the pressurized medium may be introduced and discharged through the third hydraulic port 108 formed in the cylinder block 101.

The third hydraulic port 108 is connected to the simulation flow path 15 branching from the first reservoir flow path 11 so that the pressurized medium flows from the reservoir 10 to the first master chamber 102 or, conversely, the first master chamber. The pressurized medium may be discharged from 102 to the reservoir 10.

In the simulation channel 15, a simulator check valve 13 that allows only the flow of the pressurized medium from the reservoir 10 to the first master chamber 102, and a bidirectional flow of the pressurized medium transmitted through the simulation channel 15 are controlled. The simulator valve 14 is arranged in parallel. The simulator valve 14 may be provided as a normally closed type solenoid valve that operates to open the valve when it receives an electrical signal from the electronic control unit after being in a normally closed state.

The master cylinder 100 of the present embodiment is the first master chamber due to the reaction force of the pedal simulator 110 disposed in the first master chamber 102 in a fallback mode that operates when the electronic brake system cannot operate normally. A hydraulic pressure compensation unit 200 is provided to solve the problem that the hydraulic pressure provided to the first backup passage 60 in 102 is lowered.

The hydraulic pressure compensation unit 200 includes a compensation chamber 210 provided inside the front end of the second master piston 120, and a compensation piston 220 installed to be moved forward and backward while maintaining airtightness within the compensation chamber 210. Wow, a compensation spring 230 for elastically supporting the compensation piston 220, and a compensation channel 240 for transferring the pressurized medium pressed in the compensation chamber 210 to the first backup channel 60.

The compensation chamber 210 is formed in a concave shape in a predetermined length along the axial direction of the second master piston 120 at the tip of the second master piston 120, and the front opening of the compensation chamber 210 is a compensation piston ( 220).

A sealing member 221 is installed on the outer periphery of the compensation piston 220 to block the flow of the pressurized medium between the compensation chamber 210 and the second master chamber 103.

The compensation piston 220 is positioned in a state that is elastically pressed toward the front of the compensation chamber 210 while being supported by the compensation spring 230 disposed inside the compensation chamber 210, and is located inside the front of the compensation chamber 210. As it is supported by the positioned locking projections 211, it is prevented from being separated from the compensation chamber 210.

The compensation piston 220 is pushed to the rear in the compensation chamber 210 by the pressure of the pressurized medium pressurized in the second master chamber 103 when the second master piston 120 moves forward. As the movement of 220), the pressurizing medium filled in the compensation chamber 210 is pressurized.

The pressurized medium pressurized in the compensation chamber 210 by the compensation piston 220 is discharged to the compensation channel 240 through the compensation hole 250 formed in the second master piston 120 and then the first backup channel 60 Is provided in.

The sealing member 251 installed at the rear of the compensation hole 250 seals between the second master piston 120 and the cylinder block 101 and discharges the pressure medium discharged through the compensation hole 250 into the first master chamber 102. ) To prevent leakage.

The compensation chamber 210 and the first backup passage 60 are connected to each other by the compensation passage 240.

The compensation flow path 240 has one end connected to a third backup port 109 formed in the cylinder block 101 so as to communicate with the compensation hole 250 formed in the second master piston 120, and the other end is a first backup flow path ( 60) is connected to one side.

A compensation valve 260 for controlling the flow of the pressurized medium in both directions between the compensation chamber 210 and the first master chamber 102 or the first backup channel 60 is installed in the compensation passage 240.

The compensation valve 260 may be provided as a normally open type solenoid valve that operates to close the valve when it receives an electrical signal from the electronic control unit after being opened normally.

The hydraulic pressure supply device 40 may be provided in a variety of ways and structures. For example, a piston moving by a driving force of a motor may push a pressurized medium in a chamber to deliver hydraulic pressure to the hydraulic control unit 50. Alternatively, the hydraulic pressure supply device 40 may be provided with a pump driven by a motor or a high pressure accumulator.

Specifically, when the driver applies a pedal effort to the brake pedal 20, as the displacement of the brake pedal 20 changes, an electric signal is transmitted from the pedal displacement sensor 21, and the motor operates by this signal. In addition, a power conversion unit for converting a rotational motion of the motor into a linear motion may be provided between the motor and the piston. The power conversion unit may include a worm and a worm gear and/or a rack and pinion gear.

The hydraulic control unit 50 receives hydraulic pressure and controls a hydraulic pressure transmitted to each of two wheel cylinders, and a second hydraulic circuit 52 controls hydraulic pressure transmitted to the other two wheel cylinders. Can be made. For example, the first hydraulic circuit 51 may control the left front wheel FL and the right rear wheel RR, and the second hydraulic circuit 52 may control the right front wheel FR and the left rear wheel RL. However, the position of the wheel connected to the first hydraulic circuit 51 and the second hydraulic circuit 52 is not limited thereto, and may be variously configured.

The hydraulic control unit 50 includes an inlet valve provided at a front end of each wheel cylinder 30 to control hydraulic pressure, and an outlet valve branched between the inlet valve and the wheel cylinder 30 and connected to the reservoir 10. I can. In addition, the front end of the inlet valve of the hydraulic pressure supply device 40 and the first hydraulic circuit 51 may be connected by the first hydraulic flow path 70, and the inlet valve of the hydraulic pressure supply device 40 and the second hydraulic circuit 52 The front end may be connected by the second hydraulic flow path 71, and the hydraulic pressure of the braking fluid generated and provided from the hydraulic pressure supply device 40 through the first and second hydraulic flow paths 70 and 71 It may be supplied to the circuits 51 and 52, respectively.

The backup channels 60 and 61 directly supply the hydraulic pressure of the pressurized medium discharged from the master cylinder 100 to the hydraulic control unit 50 when the electronic brake system is unable to operate normally due to a failure of the hydraulic supply device 40. This is a flow path used in a fallback mode in which braking of the wheel cylinder 30 can be implemented.

These backup passages (60, 61) include a first backup passage (60) connecting the first master chamber (102) and the first hydraulic circuit (51), the second master chamber (103) and the second hydraulic circuit (52). ) And a second backup passage 61 connecting.

A cut valve 63 for controlling the flow of the pressurized medium may be installed in the second backup passage 61. The cut valve 63 may be composed of a solenoid valve of a normal open type that operates to close when a closing signal is received from the electronic control unit after being opened normally.

A cut valve may be installed in the first backup flow path 60 like the second backup flow path 61, but in this embodiment, in order to simplify the structure of the device by reducing the number of valves, separate the first backup flow path 60 The first backup passage 60 and the outlet valve may be connected so that the outlet valve provided in the first hydraulic circuit 51 performs the function of the cut valve without installing the cut valve of.

Reference numeral PS1 is a backup flow pressure sensor that measures the hydraulic pressure of the master cylinder 20, and PS2 is a hydraulic flow path pressure sensor that senses the hydraulic pressure of the hydraulic circuit.

When the pedal simulation operation by the master cylinder 100 is described with reference to FIG. 3, the driver operates the brake pedal 20 during normal operation, and at the same time, the cut valve 63, the compensation valve 260, and the first hydraulic pressure The outlet valve provided in the circuit 51 is closed, and the simulator valve 14 of the simulation flow path 15 is opened.

As the operation of the brake pedal 20 proceeds, the first master piston 130 and the second master piston 120 advance, but the second master piston 130 and the compensation valve 260 are closed by the closing operation of the cut valve 63 and the compensation valve 260. The chamber 103 and the compensation chamber 210 are sealed, so that the second master piston 120 does not displace. Accordingly, the displacement of the first master piston 130 compresses the rubber member 111, and elastic restoring force by compression of the rubber member 111 may be provided to the driver as a pedal feel. At this time, the pressurized medium accommodated in the first master chamber 102 is delivered to the reservoir 10 through the simulation flow path 15.

In addition, as the displacement of the brake pedal 20 changes, the hydraulic pressure supply device 40 operates based on a signal sensed by the pedal displacement sensor 21, and the hydraulic pressure generated by the hydraulic pressure supply device 40 is applied to the hydraulic control unit ( 50) to the wheel cylinder 30 to generate a braking force.

Thereafter, when the driver releases the pedal effort of the brake pedal 20, the simulator spring 112 and the rubber member 111 expand by the elastic force, and the first master piston 130 returns to its original position, and the first master chamber ( A pressurized medium is supplied to and filled to 102 through a simulator valve 14 and a simulator check valve 13 installed in the simulation flow path 15.

Meanwhile, when the electronic brake system operates abnormally, that is, as shown in FIG. 4, when the driver applies a foot pressure to the brake pedal 20 in the operating state of the fallback mode, the first master piston 130 connected to the brake pedal 20 This is going forward.

When the first master piston 130 advances, the second master piston 120 advances through the rubber member 111.

In the non-operating state, since the cut valve 63 is kept open, the pressurized medium accommodated in the first master chamber 102 by the advance of the first master piston 130 is removed along the first backup passage 60. 1 The pressurized medium is transferred to the hydraulic circuit 51 and accommodated in the second master chamber 103 by the advance of the second master piston 120 toward the second hydraulic circuit 52 along the second backup passage 61. It is transmitted to implement the braking of the wheel cylinder 30.

At this time, since the pedal simulator 110 is embedded in the first master chamber 102, the pressurizing medium accommodated in the first master chamber 102 pressed by the advance of the first master piston 130 is the pedal simulator 110. It is provided to the first backup passage 60 in a state in which the hydraulic pressure is lower than that of the pressurized medium pressurized in the second master chamber 103 by the reaction force of.

However, the compensation piston 220 moves backward by the pressure of the pressurized medium pressed in the second master chamber 103 by the advance of the second master piston 120, and the compensation chamber ( The pressurized medium accommodated in 210) is delivered to the first backup passage 60 along the compensation passage 240 to compensate for the pressure drop in the first master chamber 102 in which the pedal simulator 110 is embedded. Stable braking is achieved by maintaining a balance of the hydraulic pressure provided to the first backup passage 60 and the second backup passage 61 in the 102 and the second master chamber 103, respectively.

In the above, specific embodiments have been illustrated and described. However, it is not limited only to the above-described embodiments, and those of ordinary skill in the art to which the invention pertains can perform various changes without departing from the gist of the technical idea of the invention described in the following claims.

10: reservoir, 20: brake pedal,
30: wheel cylinder, 40: hydraulic pressure supply,
50: hydraulic control unit, 100: master cylinder,
102: first master chamber, 103: second master chamber,
110: pedal simulator, 111: rubber member,
120: second master piston, 130: first master piston,
200: hydraulic pressure compensation unit, 210: compensation chamber,
220: compensation piston, 230: compensation spring,
240: reward euro, 250: reward hole,
260: compensation valve.

Claims (10)

A first master chamber pressurized by a first master piston that moves in connection with an operation of a brake pedal, a second master chamber pressurized by a second master piston, and the first master piston and the first master piston in the first master chamber. A master cylinder interposed between the second master piston and including a pedal simulator providing reaction force to the brake pedal;
A hydraulic control unit including a first hydraulic circuit receiving hydraulic pressure and controlling hydraulic pressure transmitted to each of the two wheel cylinders and a second hydraulic circuit controlling hydraulic pressure transmitted to the other two wheel cylinders;
A first backup passage connecting the first master chamber and the first hydraulic circuit;
A second backup passage connecting the second master chamber and the second hydraulic circuit; And
Including; a hydraulic pressure compensation unit for compensating for a drop in the hydraulic pressure of the first master chamber according to the reaction force of the pedal simulator in the fallback mode,
The hydraulic pressure compensation unit is configured to provide the hydraulic pressure of the pressurized medium pressurized by a compensation piston provided so as to move by the pressure of the pressurized medium accommodated in the second master chamber when the second master piston advances to the first backup passage. Electronic brake system. The method of claim 1,
The hydraulic pressure compensation unit includes a compensation chamber provided in the second master piston so that the compensation piston is slidable, and a compensation channel for transferring a pressurized medium pressurized in the compensation chamber to the first backup channel. The method of claim 2,
The compensation chamber is provided in a concave form at the front end of the first master piston, and the open front of the compensation chamber is sealed by the compensation piston slidable in the compensation chamber. The method of claim 3,
An electronic brake system in which a compensation spring is provided in the compensation chamber to provide an elastic force for pressing the compensation piston forward. The method of claim 3,
A sealing member is installed on the outer periphery of the compensation piston to block the flow of the pressurized medium between the second master chamber and the compensation chamber. The method of claim 4,
The compensation piston is supported by a locking jaw provided in the compensation chamber, and the electronic brake system is not separated from the compensation chamber. The method of claim 3,
The electronic brake system provided with a compensation hole for communicating the compensation chamber and the compensation flow path in the first master piston. The method of claim 2,
The electronic brake system is provided with a compensation valve for controlling the flow of the pressurized medium in both directions in the compensation passage. The method of claim 1,
Electronic brake system further comprising a reservoir in which the pressurized medium is stored, and a simulation channel provided with a simulator valve for connecting the reservoir and the first master chamber and controlling the flow of the pressurized medium. The method of claim 1,
An electronic brake system further comprising a hydraulic pressure supply device for generating hydraulic pressure according to an electrical signal output in response to the displacement of the brake pedal and providing the hydraulic pressure control unit.

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