JP2009143254A - Master cylinder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a master cylinder capable of improving the feeling of a brake operation. <P>SOLUTION: The master cylinder 14 is equipped with a cylinder housing 60, a first piston 62 which is slidably stored in the cylinder housing 60 and forms a first liquid chamber 78 in the cylinder housing 60, a first coupling 72 which is provided at an outer periphery of the first piston 62, and seals hydraulic oil in a first atmosphere chamber 73, and a friction member 302 which is provided at the first atmosphere chamber 73 side more than the first coupling 72, generates sliding friction with the cylinder housing 60, and has low sealing performance lower than that of the first coupling 72. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a master cylinder that is provided in an electronically controlled brake system for a vehicle and generates a hydraulic pressure corresponding to an operation of a brake operation member.

  As a brake control device for controlling the braking force of a vehicle such as an automobile, for example, one described in Patent Document 1 is known. Patent Document 1 discloses a brake hydraulic booster system including a hydraulic booster having a large hysteresis between an operation direction and an operation release direction.

In recent years, many electronically controlled brake systems that control the braking force of each wheel so as to give the vehicle the optimum braking force according to the traveling state of the vehicle have been adopted as a braking device in the vehicle (for example, Patent Documents). 2). In such an electronically controlled brake system, the wheel cylinder pressure of each wheel is monitored by a pressure sensor, and an electromagnetic flow control valve is installed so that the wheel cylinder pressure becomes a target hydraulic pressure calculated based on the pedal operation amount of the driver. I have control.
JP-A-11-286269 JP 2006-1379 A

  By the way, in the case of a conventional brake system using a booster such as a vacuum booster or a hydro booster, the sliding friction between the wheel cylinder and the piston in the caliper is transmitted to the brake pedal via the hydraulic oil, and the pedal force hysteresis is generated. .

  However, in the case of an electronically controlled brake system, since the master cylinder is separated from the wheel cylinder, the sliding friction in the caliper is not transmitted to the brake pedal. The electronically controlled brake system uses a stroke simulator to create pedal reaction force, but since the stroke simulator is mainly composed of a combination of springs, it has better pedaling force hysteresis than conventional brake systems. The driver may feel uncomfortable with the pedal feeling in the brake operation.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a master cylinder capable of improving pedal feeling in brake operation.

  In order to solve the above-described problems, a master cylinder according to an aspect of the present invention is a master cylinder that sends hydraulic oil in response to an operation of a brake operation unit, and is slidably accommodated in the cylinder housing and the cylinder housing. A piston that forms a liquid chamber in the cylinder housing, a seal member that is provided on the outer periphery of the piston and seals the hydraulic oil in the liquid chamber, and is provided closer to the liquid chamber than the seal member, and slides between the cylinder housing. A friction member that generates dynamic friction and has a lower sealing performance than the seal member.

  According to this aspect, by providing the friction member separately from the seal member that seals the hydraulic oil into the liquid chamber, it is possible to increase the hysteresis when the pedal is depressed and when the pedal is returned. As a result, the pedal feeling in the brake operation can be improved.

  In addition, if the flow of hydraulic oil is hindered by the friction member, there is a possibility that the air releasing performance of the air remaining between the seal member and the friction member may be reduced. In this aspect, the sealing performance of the friction member is sealed. Since it comprises lower than a member, a friction member does not inhibit the flow of hydraulic fluid. Accordingly, it is possible to achieve both the creation of sliding friction and the air releasing property, and thus the pedal feeling in the brake operation can be preferably improved.

  The friction member may include an oil passage that allows the flow of hydraulic oil before and after the friction member. The oil passage may be formed by a protruding portion that protrudes in the radial direction from the main body portion of the friction member. In this case, the amount of hysteresis can be changed by adjusting the number of protrusions. Since the amount of hysteresis can be controlled with a simple configuration, design management is easy and manufacturing costs can be reduced.

  ADVANTAGE OF THE INVENTION According to this invention, the master cylinder which can improve the pedal feeling in brake operation can be provided.

  The best mode for carrying out the present invention will be described below in detail with reference to the drawings.

  FIG. 1 is a diagram showing a configuration of a brake control device including a master cylinder 14 according to the first embodiment of the present invention. A brake control device 10 shown in FIG. 1 constitutes an electronically controlled brake system (ECB) for a vehicle, and brakes for four wheels of a vehicle based on an operation amount of a brake pedal 12 as a brake operation member by a driver. Is optimally controlled.

  The brake pedal 12 is connected to a master cylinder 14 that sends hydraulic oil in response to a depression operation by the driver. The detailed configuration of the master cylinder 14 will be described later. The brake pedal 12 is provided with a stroke sensor 46 for detecting the depression stroke.

  Connected to the first output port 14a of the master cylinder 14 is a stroke simulator 24 that creates a pedal stroke according to the depression force of the brake pedal 12 by the driver. The detailed configuration of the stroke simulator 24 will be described later.

  A simulator cut valve 23 is provided in the middle of the flow path connecting the master cylinder 14 and the stroke simulator 24. The simulator cut valve 23 is a normally-closed electromagnetic on-off valve that opens when energized during normal operation and closes when de-energized such as during an abnormality. The master cylinder 14 is connected to a reservoir tank 26 for storing hydraulic oil.

  A brake hydraulic control pipe 18 for the right front wheel is connected to the first output port 14a of the master cylinder 14, and the brake hydraulic control pipe 18 is a wheel cylinder for the right front wheel that applies a braking force to the right front wheel. It is connected to 20FR. A brake hydraulic control pipe 16 for the left front wheel is connected to the second output port 14b of the master cylinder 14, and the brake hydraulic control pipe 16 is used for the left front wheel that applies a braking force to the left front wheel. It is connected to the wheel cylinder 20FL.

  A right electromagnetic on-off valve 22FR is provided in the middle of the brake hydraulic control pipe 18 for the right front wheel, and a left electromagnetic on-off valve 22FL is provided in the middle of the brake hydraulic control pipe 16 for the left front wheel. The right solenoid on-off valve 22FR and the left solenoid on-off valve 22FL are both normally open solenoid valves that are open when not energized and switched to closed when energized.

  A right master pressure sensor 48FR for detecting the master cylinder pressure on the right front wheel side is provided in the middle of the brake hydraulic control pipe 18 for the right front wheel. A left master pressure sensor 48FL for measuring the master cylinder pressure on the left front wheel side is provided.

  In the brake control apparatus 10, when the brake pedal 12 is depressed by the driver, the stroke operation amount is detected by the stroke sensor 46. The master detected by the right master pressure sensor 48FR and the left master pressure sensor 48FL is detected. The depressing operation force (depressing force) of the brake pedal 12 can also be obtained from the cylinder pressure. As described above, it is preferable from the viewpoint of fail-safe that the master cylinder pressure is monitored by the two pressure sensors 48FR and 48FL on the assumption of the failure of the stroke sensor 46. Hereinafter, the right master pressure sensor 48FR and the left master pressure sensor 48FL are collectively referred to as a master cylinder pressure sensor 48 as appropriate.

  On the other hand, one end of a hydraulic supply / discharge pipe 28 is connected to the reservoir tank 26, and a suction port of an oil pump 34 driven by a motor 32 is connected to the other end of the hydraulic supply / discharge pipe 28. . The discharge port of the oil pump 34 is connected to a high pressure pipe 30, and an accumulator 50 and a relief valve 53 are connected to the high pressure pipe 30. In the present embodiment, a reciprocating pump having two or more pistons (not shown) that are reciprocally moved by the motor 32 is employed as the oil pump 34. As the accumulator 50, an accumulator 50 that converts the pressure energy of hydraulic oil into pressure energy of an enclosed gas such as nitrogen is stored.

  The accumulator 50 stores the hydraulic oil whose pressure has been increased to about 14 to 22 MPa by the oil pump 34, for example. Further, the valve outlet of the relief valve 53 is connected to the hydraulic supply / exhaust pipe 28. When the pressure of the hydraulic oil in the accumulator 50 increases abnormally to, for example, about 25 MPa, the relief valve 53 is opened and the high pressure operation is performed. The oil is returned to the hydraulic supply / discharge pipe 28. Further, the high-pressure pipe 30 is provided with an accumulator pressure sensor 51 that detects an outlet pressure of the accumulator 50, that is, a pressure of hydraulic oil in the accumulator 50.

  The high pressure pipe 30 is connected to the right front wheel wheel cylinder 20FR, the left front wheel wheel cylinder 20FL, the right rear wheel wheel cylinder 20RR, and the left rear wheel through the pressure increasing valves 40FR, 40FL, 40RR, and 40RL. It is connected to the cylinder 20RL. Hereinafter, the wheel cylinders 20FR to 20RL will be collectively referred to as “wheel cylinders 20”, and the pressure increase valves 40FR to 40RL will be appropriately collectively referred to as “pressure increase valves 40”. Each of the pressure increasing valves 40 is a normally closed electromagnetic flow control valve (linear valve) that is closed when not energized and is used to increase the pressure of the wheel cylinder 20 as necessary. A disc brake unit is provided for each wheel of the vehicle (not shown), and each disc brake unit generates a braking force by pressing the brake pad against the disc by the action of the wheel cylinder 20.

  Further, the wheel cylinder 20FR for the right front wheel and the wheel cylinder 20FL for the left front wheel are connected to the hydraulic supply / discharge pipe 28 via the pressure reducing valve 42FR or 42FL, respectively. The pressure reducing valves 42FR and 42FL are normally closed electromagnetic flow control valves (linear valves) used for pressure reduction of the wheel cylinders 20FR and 20FL as necessary. On the other hand, the wheel cylinder 20RR for the right rear wheel and the wheel cylinder 20RL for the left rear wheel are connected to the hydraulic supply / discharge pipe 28 via a pressure reducing valve 42RR or 42RL which is a normally open electromagnetic flow control valve. . Hereinafter, the pressure reducing valves 42FR to 42RL are collectively referred to as “pressure reducing valve 42” as appropriate.

  A wheel cylinder for detecting a wheel cylinder pressure, which is a pressure of hydraulic oil acting on the corresponding wheel cylinder 20, in the vicinity of the wheel cylinders 20FR to 20RL for the right front wheel, the left front wheel, the right rear wheel, and the left rear wheel. Pressure sensors 44FR, 44FL, 44RR and 44RL are provided. Hereinafter, the wheel cylinder pressure sensors 44FR to 44RL are collectively referred to as “wheel cylinder pressure sensor 44” as appropriate.

  The right electromagnetic on-off valve 22FR and the left electromagnetic on-off valve 22FL, the pressure increasing valves 40FR to 40RL, the pressure reducing valves 42FR to 42RL, the oil pump 34, the accumulator 50, and the like constitute the hydraulic actuator 81 of the brake control device 10. The hydraulic actuator 81 is controlled by an electronic control unit (hereinafter referred to as “ECU”) 200.

  The ECU 200 functions as a control unit that controls the wheel cylinder pressure in the wheel cylinders 20FR to 20RL. The ECU 200 is a nonvolatile memory such as a CPU that executes various arithmetic processes, a ROM that stores various control programs, a RAM that is used as a work area for data storage and program execution, and a backup RAM that can retain stored contents even when the engine is stopped. An A / D converter for converting an analog signal input from a memory, an input / output interface, various sensors, and the like into a digital signal and taking it in, a timer for timing, and the like are provided.

  The ECU 200 is electrically connected to various actuators including the hydraulic on-off valves 81FR, 22FL, the simulator cut valve 23, the pressure increasing valves 40FR to 40RL, the pressure reducing valves 42FR to 42RL, and the like.

  The ECU 200 is electrically connected to various sensors and switches that output signals for use in control. That is, a signal indicating the wheel cylinder pressure in the wheel cylinders 20FR to 20RL is input to the ECU 200 from the wheel cylinder pressure sensors 44FR to 44RL.

  Further, a signal indicating the pedal stroke of the brake pedal 12 is input from the stroke sensor 46 to the ECU 200, and signals indicating the master cylinder pressure are input from the right master pressure sensor 48FR and the left master pressure sensor 48FL, and from the accumulator pressure sensor 51. A signal indicating the accumulator pressure is input.

  Further, although not shown, ECU 200 receives a signal indicating the wheel speed of each wheel from a wheel speed sensor installed for each wheel, a signal indicating a yaw rate from the yaw rate sensor, and a steering wheel from the steering angle sensor. A signal indicating the steering angle is input.

  In the brake control device 10 configured as described above, when the brake pedal 12 is depressed by the driver, the ECU 200 calculates the target deceleration of the vehicle from the pedal stroke representing the depression amount of the brake pedal 12 and the master cylinder pressure. Then, a target hydraulic pressure that is a target value of the wheel cylinder pressure of each wheel is obtained in accordance with the calculated target deceleration. Then, the ECU 200 controls the pressure increasing valve 40 and the pressure reducing valve 42 so that the wheel cylinder pressure of each wheel becomes the target hydraulic pressure.

  On the other hand, at this time, the electromagnetic on-off valves 22FR and 22FL are closed, and the simulator cut valve 23 is opened. Therefore, the hydraulic oil sent from the master cylinder 14 by the depression of the brake pedal 12 by the driver flows into the stroke simulator 24 through the simulator cut valve 23.

  When the accumulator pressure is less than the lower limit value of the preset control range, the oil pump 34 is driven by the ECU 200 to increase the accumulator pressure. When the accumulator pressure enters the control range, the drive of the oil pump 34 is stopped. Is done.

  FIG. 2 is a diagram for explaining the configuration of the master cylinder 14 according to the first embodiment of the present invention. The master cylinder 14 includes a cylinder housing 60, a first piston 62, a second piston 64, and a friction member 302.

  The master cylinder 14 has a first piston 62 slidably accommodated in a cylinder housing 60. A piston rod 70 connected to the brake pedal 12 is provided at one end of the first piston 62. Further, a second piston 64 is slidably accommodated in the cylinder housing 60. By inserting the two pistons into the cylinder housing 60 in this way, a first liquid chamber 78 is formed between the first piston 62 and the second piston 64, and the second piston 64 and the bottom of the cylinder housing 60 are A second liquid chamber 80 is formed between the two.

  A first spring 66 is provided between the first piston 62 and the second piston 64 with a predetermined mounting load, and a second spring is provided between the second piston 64 and the bottom of the cylinder housing 60. 68 is provided.

  The first output port 14a of the master cylinder 14 communicates with the first fluid chamber 78, and the brake oil pressure control pipe 18 for the right front wheel is connected to the first output port 14a. Further, as described above, the stroke simulator 24 is connected to the first output port 14a via the brake hydraulic pressure control pipe 18. In FIG. 2, the second output port communicating with the second fluid chamber 80 and the simulator cut valve provided between the brake hydraulic control pipe 18 and the stroke simulator 24 are not shown.

  Two annular grooves are formed on the outer peripheral surface of the first piston 62. The first coupling 72 is accommodated in the groove on the one piston rod 70 side, and the second coupling 74 is accommodated in the groove on the other first liquid chamber 78 side. The first coupling 72 and the second coupling 74 are cross-sectional cup-shaped seal members formed of an elastic material such as rubber. The first coupling 72 and the second coupling 74 are provided such that the inner surface of the cup faces the front in the axial direction of the master cylinder 14, and the first coupling 72 and the second coupling 74 are provided between the first coupling 72 and the second coupling 74. One atmospheric pressure chamber 73 is formed. The first atmospheric pressure chamber 73 communicates with a reservoir tank (not shown) via a first input port 71 provided on the side surface of the cylinder housing 60. In this specification, the front in the axial direction of the master cylinder 14 is the direction in which the first piston 62 moves when the brake pedal 12 is depressed, and the rear in the axial direction of the master cylinder 14 is the brake pedal. This is the direction in which the first piston 62 moves when the step 12 is released and the predetermined position returns.

  Two annular grooves are also formed on the outer peripheral surface of the second piston 64. The third coupling 76 is accommodated in the groove on the side of the first liquid chamber 78, and the fourth coupling 77 is accommodated in the groove on the side of the second liquid chamber 80. The third coupling 76 is provided such that the inner surface of the cup faces the rearward in the axial direction of the master cylinder 14, and the fourth coupling 77 is arranged so that the inner surface of the cup faces the frontward in the axial direction of the master cylinder 14. Is provided. A second atmospheric pressure chamber 75 is formed between the third coupling 76 and the fourth coupling 77. The second atmospheric pressure chamber 75 communicates with the reservoir tank via a second input port 79 provided on the side surface of the cylinder housing 60.

  As described above, the stroke simulator 24 creates a pedal stroke corresponding to the depression force of the brake pedal 12 by the driver. In the stroke simulator 24, a piston 162 is accommodated in a cylinder housing 160 having a bottomed cylindrical shape via a coupling 172 so as to be fluid-tightly slidable. In the stroke simulator 24, a liquid chamber 178 and an atmospheric pressure chamber 180 are formed in the cylinder housing 160 by the piston 162. A first spring 166 and a second spring 167 are provided in the atmospheric pressure chamber 180 so as to bias the piston 162 toward the liquid chamber 178 side. The fluid chamber 178 of the stroke simulator 24 is communicated with the first fluid chamber 78 of the master cylinder 14 via the input port 182 and the brake hydraulic pressure control pipe 18. The atmospheric pressure chamber 180 of the stroke simulator 24 is communicated with the first atmospheric pressure chamber 73 of the master cylinder 14 or the reservoir tank via an output port (not shown).

  In the master cylinder 14 configured as described above, when the brake pedal 12 is stepped on and the first piston 62 moves forward, the cup of the first coupling 72 opens radially outward, and thus the inside of the first atmospheric pressure chamber 73. This prevents the hydraulic oil from leaking out of the cylinder housing 60. At this time, the cups of the second coupling 74 and the third coupling 76 are opened radially outward, so that the hydraulic oil in the first liquid chamber 78 is sealed, and the master cylinder pressure is applied to the first liquid chamber 78. appear. In the first embodiment, in the normal control state of the brake control device 10, the left electromagnetic on-off valve 22FL that communicates with the second output port 14b of the second fluid chamber 80 is closed. The two pistons 64 do not move.

  When the brake pedal 12 is depressed and the first piston 62 moves forward, the piston 162 is pushed against the biasing force of the first spring 166 and the second spring 167 by the master cylinder pressure in the stroke simulator 24. . At this time, a pedal reaction force is created by the first spring 166 and the second spring 167.

  FIG. 3 is a diagram for explaining the master cylinder 14 according to the first embodiment of the present invention in more detail. 3, the peripheral part of the first piston 62 of the master cylinder 14 is shown enlarged.

  In the master cylinder 14 according to the first embodiment, as shown in FIG. 3, a friction member 302 is provided on the outer periphery of the first piston 62. The friction member 302 is a donut-shaped member made of an elastic material such as rubber, and is housed in a friction member housing groove 304 formed on the outer peripheral surface of the first piston 62. In the first embodiment, the friction member 302 is provided axially forward of the first coupling 72 and axially rearward of the second coupling 74. That is, the friction member 302 is provided between the first coupling 72 and the second coupling 74. The friction member 302 generates sliding friction with the cylinder housing 60. Further, the friction member 302 has a lower sealing performance than the first coupling 72. The sliding friction generated between the friction member 302 and the cylinder housing 60 is preferably higher than the sliding friction generated between the first coupling 72 and the cylinder housing 60.

  FIG. 4 is a view for explaining the friction member 302. FIG. 4 illustrates an XX cross section of the master cylinder 14 illustrated in FIG. 3.

  As shown in FIG. 4, the friction member 302 is provided between the inner peripheral surface of the cylinder housing 60 and the outer peripheral surface of the first piston 62. The friction member 302 includes an annular base portion 302a, a radially outward projecting portion 302b protruding radially outward from the outer peripheral surface of the base portion 302a, and a radially inward direction from the inner peripheral surface of the base portion 302a. And a radially inwardly projecting portion 302c projecting from the inner surface.

  In the first embodiment, as shown in FIG. 4, six radially outward projections 302b and six radial inward projections 302c are formed. The radially outward projecting portions 302b are formed at equal intervals in the circumferential direction, and the radially inward projecting portion 302c is formed at an intermediate portion between the adjacent radially outward projecting portions 302b.

  In the master cylinder 14, the distal end portions of the radially outward projecting portions 302 b are in pressure contact with the inner peripheral surface of the cylinder housing 60. Each radial inward protruding portion 302 c is in pressure contact with the outer peripheral surface of the first piston 62.

  In the master cylinder 14, an outer oil passage 306 is formed by two adjacent radially outward projecting portions 302b, an inner peripheral surface of the cylinder housing 60, and an outer peripheral surface of the base portion 302a. In the first embodiment, since six radially outward protruding portions 302b are formed, six outer oil passages 306 are formed. Further, an inner oil passage 308 is formed by two adjacent radially inward protruding portions 302c, the outer peripheral surface of the first piston 62, and the inner peripheral surface of the base portion 302a. In the first embodiment, since six radial inward protruding portions 302c are formed, six inner oil passages 308 are formed.

  FIG. 5 is a diagram illustrating hysteresis characteristics when the master cylinder 14 according to the first embodiment is used. In FIG. 5, the horizontal axis represents the pedal depression force F, and the vertical axis represents the pedal stroke S. In FIG. 5, a thick solid line α indicates a hysteresis characteristic when the master cylinder 14 according to the first embodiment is used. A thin solid line β represents the hysteresis characteristic of the master cylinder without the friction member 302 for comparison. As shown in FIG. 5, when the master cylinder 14 according to the first embodiment is used, the amount of hysteresis can be increased as compared with the case where the friction member 302 is not provided.

  As described above, according to the master cylinder 14 according to the first embodiment, the distal ends of the radially outward projecting portion 302b and the radially inward projecting portion 302c are the inner peripheral surface of the cylinder housing 60 and the first end portion, respectively. By being in pressure contact with the outer peripheral surface of the one piston 62, sliding friction can be generated between the piston 62 and the cylinder housing 60. Thereby, since the amount of hysteresis can be improved, the pedal feeling in brake operation can be improved.

  Further, when a normal O-ring is simply used as the friction member, sliding friction can be generated between the cylinder housing and the hydraulic oil, but the flow of hydraulic oil is obstructed by the O-ring. There is a possibility that the air releasing property of the air remaining between the friction member 302 and the first coupling 72 may be reduced. In the master cylinder 14 according to the first embodiment, the outer oil passage 306 and the inner oil passage 308 are formed by providing the friction member 302 with the radially outward protrusion 302b and the radially inward protrusion 302c. Therefore, the sealing performance of the hydraulic oil is lower than that of the first coupling 72, and the flow of the hydraulic oil around the friction member 302 is allowed. Accordingly, it is possible to achieve both the creation of sliding friction and the ability to release air, so that it is possible to preferably improve the pedal feeling in the brake operation.

  In the master cylinder 14 according to the first embodiment, six radially outward protruding portions 302b and radially inward protruding portions 302c are formed on each of the friction members 302, but the radially outer protruding portion 302b and the radially inner protruding portion 302c The number of the lateral protrusions 302c is not limited to six, and the amount of hysteresis can be changed by adjusting the number of the radially outward protrusions 302b and the radially inward protrusions 302c. Further, the amount of hysteresis can be changed not only by the number of the radially outward protrusions 302b and the radially inward protrusions 302c but also by changing the protrusion height and shape. In this way, the hysteresis amount can be controlled with a simple configuration, so that the manufacturing cost can be reduced.

  In the master cylinder 14 according to the first embodiment, since the friction member 302 is provided in the first atmospheric pressure chamber 73 filled with hydraulic oil, the sliding surface of the friction member 302 is in a wet state. . Therefore, variation in sliding friction due to temperature and brake usage frequency can be reduced, and as a result, variation in hysteresis amount can be reduced. Further, since the inside of the first atmospheric pressure chamber 73 filled with hydraulic oil is slid, the durability of the friction member 302 can be improved.

  In the case of the master cylinder 14 according to the first embodiment, the friction member 302 is provided in the first atmospheric pressure chamber 73. Therefore, for example, when the radially outward projecting portion and the radially inward projecting portion of the friction member 302 are worn, the outer oil passage and the inner oil passage become smaller, and the air venting performance in the first atmospheric pressure chamber 73 is lowered. Even in this case, there is an advantage that the brake performance is not affected.

  FIG. 6 is a view for explaining a master cylinder 600 according to the second embodiment of the present invention. FIG. 6 is an enlarged view of the periphery of the first piston 62 of the master cylinder 600. In addition, in the master cylinder 600 shown in FIG. 6, the same code | symbol is attached | subjected to the component which is the same as or corresponding to the master cylinder 14 shown in FIG. 2, and the overlapping description is abbreviate | omitted suitably.

  In the master cylinder 600 according to the second embodiment, the friction member 302 is provided on the outer periphery of the first piston 62, but the point that the friction member 302 is provided in the axial direction forward from the second coupling 74 is the first embodiment. It differs from the master cylinder 14 concerned.

  Even when the friction member 302 is provided axially forward from the second coupling 74 as in the master cylinder 600 according to the second embodiment, the radially outward projecting portion and the radially inward projecting portion of the friction member 302 are also provided. The front end of each part is in pressure contact with the inner peripheral surface of the cylinder housing 60 and the outer peripheral surface of the first piston 62, so that sliding friction with the cylinder housing 60 can be generated. Thereby, since the amount of hysteresis can be improved, the pedal feeling in brake operation can be improved.

  Moreover, since the outer oil passage and the inner oil passage are formed by providing the friction member 302 with the radially outward projecting portion and the radially inward projecting portion, the hydraulic oil is more than in the second coupling 74. The sealing performance is lowered, and the flow of hydraulic oil around the friction member 302 is allowed. Accordingly, it is possible to achieve both the creation of sliding friction and the air releasing property, and thus the pedal feeling in the brake operation can be preferably improved.

  Further, by providing the friction member 302 in the first liquid chamber 78 filled with hydraulic oil, it is possible to reduce variations in sliding friction due to temperature and brake usage frequency, and to improve the durability of the friction member 302. These are the same as those of the master cylinder 14 according to the first embodiment.

  FIG. 7 is a view for explaining a master cylinder 700 according to the third embodiment of the present invention. FIG. 7 is an enlarged view of the peripheral portion of the second piston 64 of the master cylinder 700. In addition, in the master cylinder 700 shown in FIG. 7, the same code | symbol is attached | subjected to the component which is the same as or corresponds to the master cylinder 14 shown in FIG. 2, and the overlapping description is abbreviate | omitted suitably.

  A master cylinder 700 according to the third embodiment is an embodiment when a stroke simulator (not shown) is connected to the second liquid chamber 80. When a stroke simulator is connected to the second liquid chamber 80, the second piston 64 moves together with the first piston when the brake pedal is depressed, so the friction member 302 may be provided on the second piston 64. In the master cylinder 700 according to the third embodiment shown in FIG. 7, the friction member 302 is provided on the outer periphery of the second piston 64 at a site rearward in the axial direction from the third coupling 76.

  Even when the friction member 302 is provided axially rearward of the third coupling 76 as in the master cylinder 700 according to the third embodiment, the radially outward projecting portion and the radially inward portion of the friction member 302 are also provided. The front end of the projecting portion is in pressure contact with the inner peripheral surface of the cylinder housing 60 and the outer peripheral surface of the second piston 64, so that sliding friction can be generated between the projecting portion and the cylinder housing 60. Thereby, since the amount of hysteresis can be improved, the pedal feeling in brake operation can be improved.

  Moreover, since the outer oil passage and the inner oil passage are formed by providing the friction member 302 with the radially outward projecting portion and the radially inward projecting portion, the hydraulic oil is more than in the third coupling 76. The sealing performance is lowered, and the flow of hydraulic oil around the friction member 302 is allowed. Accordingly, it is possible to achieve both the creation of sliding friction and the air releasing property, and thus the pedal feeling in the brake operation can be preferably improved.

  Further, by providing the friction member 302 in the first liquid chamber 78 filled with hydraulic oil, it is possible to reduce variations in sliding friction due to temperature and brake usage frequency, and to improve the durability of the friction member 302. These are the same as those of the master cylinder 14 according to the first embodiment.

  FIG. 8 is a view for explaining a master cylinder 800 according to the fourth embodiment of the present invention. FIG. 8 is an enlarged view of the periphery of the second piston 64 of the master cylinder 800. In addition, in the master cylinder 800 shown in FIG. 8, the same code | symbol is attached | subjected to the component which is the same as or corresponds to the master cylinder 14 shown in FIG. 2, and the overlapping description is abbreviate | omitted suitably.

  The master cylinder 800 according to the fourth embodiment is also an embodiment when a stroke simulator (not shown) is connected to the second liquid chamber 80. When a stroke simulator is connected to the second liquid chamber 80, as shown in FIG. 8, a portion of the outer periphery of the second piston 64 that is axially forward of the third coupling 76 and axially rearward of the fourth coupling 77. In other words, the friction member 302 may be provided at a portion between the third coupling 76 and the fourth coupling 77.

  Even when the friction member 302 is provided between the third coupling 76 and the fourth coupling 77 as in the master cylinder 800 according to the fourth embodiment, the radially outward projecting portion and the diameter of the friction member 302 are also provided. The tip of the direction inward protruding portion is in pressure contact with the inner peripheral surface of the cylinder housing 60 and the outer peripheral surface of the second piston 64, respectively, so that sliding friction can be generated between the front end portion and the cylinder housing 60. . Thereby, since the amount of hysteresis can be improved, the pedal feeling in brake operation can be improved.

  Moreover, since the outer oil passage and the inner oil passage are formed by providing the friction member 302 with the radially outward projecting portion and the radially inward projecting portion, the hydraulic oil is more than in the third coupling 76. The sealing performance is lowered, and the flow of hydraulic oil around the friction member 302 is allowed. Accordingly, it is possible to achieve both the creation of sliding friction and the air releasing property, and thus the pedal feeling in the brake operation can be preferably improved.

  Further, by providing the friction member 302 in the second atmospheric pressure chamber 75 filled with hydraulic oil, it is possible to reduce variations in sliding friction due to temperature and brake usage frequency, and to improve the durability of the friction member 302. The points and the like are the same as those of the master cylinder 14 according to the first embodiment.

  In the case of the master cylinder 800 according to the fourth embodiment, the friction member 302 is provided in the second atmospheric pressure chamber 75. Accordingly, for example, when the radially outward projecting portion and the radially inward projecting portion of the friction member 302 are worn, the outer oil passage and the inner oil passage become smaller, and the air venting performance in the second atmospheric pressure chamber 75 is lowered. Even in this case, there is an advantage that the brake performance is not affected.

  FIG. 9 is a view for explaining a master cylinder 900 according to the fifth embodiment of the present invention. FIG. 9 is an enlarged view of the periphery of the second piston 64 of the master cylinder 900. In addition, in the master cylinder 900 shown in FIG. 9, the same code | symbol is attached | subjected to the component which is the same as or corresponding to the master cylinder 14 shown in FIG. 2, and the overlapping description is abbreviate | omitted suitably.

  The master cylinder 900 according to the fifth embodiment is also an embodiment when a stroke simulator (not shown) is connected to the second liquid chamber 80. When a stroke simulator is connected to the second liquid chamber 80, as shown in FIG. 9, a friction member 302 may be provided on the outer periphery of the second piston 64 at a site ahead of the fourth coupling 77 in the axial direction.

  Even when the friction member 302 is provided in front of the fourth coupling 77 in the axial direction as in the master cylinder 900 according to the fifth embodiment, the radially outward projecting portion and the radially inward portion of the friction member 302 are also provided. The front end of the projecting portion is in pressure contact with the inner peripheral surface of the cylinder housing 60 and the outer peripheral surface of the second piston 64, so that sliding friction can be generated between the projecting portion and the cylinder housing 60. Thereby, since the amount of hysteresis can be improved, the pedal feeling in brake operation can be improved.

  Moreover, since the outer oil passage and the inner oil passage are formed by providing the friction member 302 with the radially outward projecting portion and the radially inward projecting portion, the hydraulic oil is more than in the fourth coupling 77. The sealing performance is lowered, and the flow of hydraulic oil around the friction member 302 is allowed. Accordingly, it is possible to achieve both the creation of sliding friction and the air releasing property, and thus the pedal feeling in the brake operation can be preferably improved.

  Further, by providing the friction member 302 in the second liquid chamber 80 filled with hydraulic oil, it is possible to reduce variations in sliding friction due to temperature and brake usage frequency, and to improve the durability of the friction member 302. These are the same as those of the master cylinder 14 according to the first embodiment.

  The present invention has been described above based on the embodiment. It should be understood by those skilled in the art that these embodiments are exemplifications, and that various modifications can be made to the combination of each component and each processing process, and such modifications are also within the scope of the present invention.

It is a figure which shows the structure of the brake control apparatus provided with the master cylinder which concerns on the 1st Embodiment of this invention. It is a figure for demonstrating the structure of the master cylinder which concerns on the 1st Embodiment of this invention. It is a figure for demonstrating in detail the master cylinder which concerns on the 1st Embodiment of this invention. It is a figure for demonstrating a friction member. It is a figure which shows the hysteresis characteristic at the time of using the master cylinder which concerns on 1st Embodiment. It is a figure for demonstrating the master cylinder which concerns on the 2nd Embodiment of this invention. It is a figure for demonstrating the master cylinder which concerns on the 3rd Embodiment of this invention. It is a figure for demonstrating the master cylinder which concerns on the 4th Embodiment of this invention. It is a figure for demonstrating the master cylinder which concerns on the 5th Embodiment of this invention.

Explanation of symbols

  10 brake control device, 12 brake pedal, 14, 600, 700, 800, 900 master cylinder, 20 wheel cylinder, 24 stroke simulator, 26 reservoir tank, 40 pressure increasing valve, 42 pressure reducing valve, 60 cylinder housing, 62 first piston, 64 second piston, 66 first spring, 68 second spring, 70 piston rod, 72 first coupling, 74 second coupling, 76 third coupling, 77 fourth coupling, 78 first liquid chamber, 80 Second fluid chamber, 200 ECU, 302 friction member, 306 outer oil passage, 308 inner oil passage.

Claims (3)

A master cylinder that delivers hydraulic oil in response to an operation of a brake operation means,
A cylinder housing;
A piston which is slidably accommodated in the cylinder housing and forms a liquid chamber in the cylinder housing;
A seal member provided on an outer periphery of the piston and sealing the hydraulic oil in the liquid chamber;
A friction member that is provided closer to the liquid chamber than the seal member, generates sliding friction with the cylinder housing, and has a lower sealing performance than the seal member;
A master cylinder comprising:   The master cylinder according to claim 1, wherein the friction member includes an oil passage that allows a flow of hydraulic oil before and after the friction member.   The master cylinder according to claim 2, wherein the oil passage is formed by a projecting portion that projects in a radial direction from a main body portion of the friction member.

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