JP5719661B2 - Master cylinder - Google Patents

Description

  The present invention relates to a master cylinder that supplies hydraulic pressure to a wheel cylinder of a vehicle.

  There are vehicles that perform braking by coordinating the braking force of a hydraulic brake device and the regenerative braking force of a motor. In the master cylinder of the hydraulic brake device mounted on such a vehicle, in order to improve the regeneration efficiency, in order to give priority to regeneration by the motor, an invalid stroke that does not increase the hydraulic pressure to the wheel cylinder during the initial operation of the brake pedal is provided. Some have been set longer (see, for example, Patent Document 1).

JP 2006-96218 A

  If the invalid stroke of the master cylinder is lengthened as described above, if the regenerative braking response is not sufficient, the invalid stroke may become an invalid stroke when generating braking force during sudden braking, resulting in a longer pedal stroke. There is sex.

  Accordingly, an object of the present invention is to provide a master cylinder that can contribute to improving the regeneration efficiency and further suppress an increase in the pedal stroke during sudden braking.

In order to achieve the above object, the present invention provides a bottomed cylindrical cylinder body into which hydraulic fluid is introduced from a reservoir, and a pressure chamber in the cylinder body that is slidably fitted to the cylinder body. A hydraulic piston that is formed, and a reaction force piston that is provided closer to the opening of the cylinder body than the hydraulic piston and presses the hydraulic piston when a predetermined amount is moved by a brake pedal operation input from a non-braking position A reaction force liquid chamber formed between the reaction force piston and the hydraulic piston and provided with a reaction force spring; a communication path communicating between the reaction force liquid chamber and the reservoir; and the cylinder A seal member that shuts off the communication between the reaction path and the reaction force liquid chamber as the reaction force piston moves with respect to the main body and confines the working fluid in the reaction force liquid chamber. The passage is formed by the seal member. The working fluid in the reaction force liquid chamber moves to the reservoir between the communication path and the reaction force liquid chamber from the communication state to the cutoff state, and an orifice is provided in the middle. The orifice smoothly flows hydraulic fluid from the reaction force fluid chamber to the reservoir so that the reaction force piston contacts the hydraulic pressure piston when the operation input of the brake pedal is a slow operation. When the brake pedal operation input is a rapid operation at a speed faster than the slow operation, the flow of hydraulic fluid from the reaction force fluid chamber to the reservoir is inhibited so that the fluid pressure in the reaction force fluid chamber increases. It is characterized by its size .

  The present invention also includes a bottomed cylindrical cylinder body into which hydraulic fluid is introduced from a reservoir, and a hydraulic piston that is slidably fitted to the cylinder body and defines a pressure chamber in the cylinder body. A reaction force piston provided closer to the opening of the cylinder body than the pressure chamber and moving in response to an operation of a brake pedal to move the hydraulic piston by a predetermined amount from a non-braking position; and the reaction force A reaction force liquid chamber formed between the piston and the hydraulic piston and provided with a reaction force spring. The reaction force liquid chamber communicates with the pressure chamber, and an orifice is provided in the middle. It is characterized by having a communicating path.

The present invention also includes a bottomed cylindrical cylinder body into which hydraulic fluid is introduced from a reservoir, a piston that is slidably fitted to the cylinder body and defines a pressure chamber in the cylinder body, A communication path that communicates between the reservoir and the pressure chamber, and a seal member that communicates and blocks between the communication path and the pressure chamber as the piston moves relative to the cylinder body. And an opening / closing valve that is provided closer to the reservoir than the orifice and communicates with and shuts off the orifice in accordance with the flow rate of the working fluid that passes through the orifice. The flow of the hydraulic fluid from the pressure chamber to the reservoir in the passage communicating between the reservoir and the pressure chamber in parallel with the orifice is cut off from the reservoir to the pressure chamber. A check valve that allows the flow of Doeki, is characterized in that is provided.

  ADVANTAGE OF THE INVENTION According to this invention, it can contribute to a regeneration efficiency improvement and can suppress the increase in the pedal stroke at the time of sudden braking on that.

It is a key map of the brake system to which the master cylinder of this embodiment is applied. It is sectional drawing which shows the master cylinder of 1st Embodiment. It is sectional drawing which shows the master cylinder of 2nd Embodiment. It is sectional drawing which shows the master cylinder of 3rd Embodiment. It is sectional drawing which shows the master cylinder of 4th Embodiment. It is sectional drawing which shows the master cylinder of 5th Embodiment. It is an expanded sectional view which shows the A section of FIG. 5 of the master cylinder of 5th Embodiment. It is sectional drawing which shows the master cylinder of 6th Embodiment. It is sectional drawing which shows the master cylinder of a reference technique .

  Before describing details of the master cylinder 11 according to the following first to seventh embodiments, an automobile brake system 200 using the master cylinder 11 according to the first to seventh embodiments will be described with reference to FIG. The brake system 200 is connected to the master cylinder 11, the booster 201 to which the master cylinder 11 is attached, the primary discharge path 40 and the secondary discharge path 39 of the master cylinder 11, and the wheel brake wheel of each wheel Wa to Wd. A hydraulic pressure control device 500 that supplies brake hydraulic pressure to the cylinders Ba to Bd, a controller 700 that controls the hydraulic pressure control device 500, and a regenerative brake device 800 that performs regenerative braking are provided.

  The hydraulic pressure control device 5 supplies the hydraulic pressure from the primary discharge passage 40 of the master cylinder 110 to the wheel cylinders Ba and Bb of the brake device for the left front wheel Wa and the right rear wheel Wb (see FIG. 1). The second fluid for supplying the fluid pressure from the secondary discharge port 39 to the wheel cylinders Bc and Bd of the brake device for the right front wheel Wc and the left rear wheel Wd. There are two systems of hydraulic circuits, so-called “X pipes”, which are composed of a pressure circuit 5B (a part on the left side of the center of the hydraulic control device 500 in FIG. 1). In this embodiment, the wheel brake is a hydraulic disc brake that supplies hydraulic pressure to the wheel cylinders Ba to Bd to advance the piston and presses the brake pad against the disc rotor that rotates with the wheel to generate a braking force. However, other hydraulic brakes such as a known drum brake may be used.

  The first hydraulic circuit 505A and the second hydraulic circuit 505B have the same configuration, and the hydraulic circuits connected to the wheel cylinders Ba to Bd of the wheel brakes of the wheels Wa to Wd have the same configuration. In the following description, the subscripts A and B and a to d of the reference numerals indicate that they correspond to the first hydraulic circuit 505A and the second hydraulic circuit 505B, and the wheels Wa to Wd, respectively. ing.

  The hydraulic pressure control device 500 includes supply valves 535A and 535B that are electromagnetic on-off valves that control the supply of hydraulic pressure from the master cylinder 11 to the wheel cylinders Ba to Bd of the wheel brakes of the wheels Wa to Wd, and the brake device Ba. To the pressure increase valves 536a to 536d which are electromagnetic on-off valves for controlling the supply of the hydraulic pressure to Bd, the system reservoirs 537A and 537B for releasing the hydraulic pressure from the wheel cylinders Ba to Bd, and the system from the wheel cylinders Ba to Bd Pressure reducing valves 538a to 538d that are solenoid valve on / off valves that control the release of fluid pressure to the reservoirs 537A and 537B, pumps 539A and 539B, and pumps 539A and 539B for supplying fluid pressure to the 5-wheel cylinders Ba to Bd The pump motor 540 to be driven and the suction of pumps 539A and 539B from the master cylinder 11 Pressurizing valves 541A, 541B that are electromagnetic on-off valves that control the supply of hydraulic pressure to the inlet side, and check valves 542A, 542B, 543A for preventing backflow from the downstream side to the upstream side of the pumps 539A, 539B, 543B, 544A, 544B, and hydraulic pressure sensors 545A, 545B for detecting the hydraulic pressures of the primer discharge port 40 and the secondary discharge port 39 of the master cylinder 11.

The hydraulic pressure control device 500 controls the operation of the supply valves 535A and 535B, the pressure increasing valves 536a to 536d, the pressure reducing valves 538a to 538d, the pressure increasing valves 541A and 541B and the pump motor 540 by the controller 700 as follows. An operating mode can be performed.
[Normal braking mode]
During normal braking, the supply valves 535A and 535B and the pressure increasing valves 536a to 536d are opened, and the pressure reducing valves 538a to 538d and the pressure increasing valves 541A and 541B are closed, so that the master cylinder 11 changes the wheel cylinders Ba to Bd of the wheels Wa to Wd. Supply hydraulic pressure.
[Decompression mode]
In the pressure reducing mode, the pressure reducing valves 538a to 538d are opened and the supply valves 535A and 535B, the pressure increasing valves 536a to 536d and the pressure increasing valves 541A and 541B are closed, thereby releasing the hydraulic pressures of the wheel cylinders Ba to Bd to the reservoirs 537A and 537B. And depressurize.
[Retention mode]
In the holding mode, the hydraulic pressures of the wheel cylinders Ba to Bd are held by closing the pressure increasing valves 536a to 536d and the pressure reducing valves 538a to 538d.
[Pressure increase mode]
In the pressure increasing mode, the pressure increasing valves 536a to 536d are opened, the supply valves 535A and 535B, the pressure reducing valves 538a to 538d and the pressure increasing valves 541A and 541B are closed, and the pump motor 540 is operated, whereby the brake fluid is stored in the reservoirs 537A and 537B. To the master cylinder 11 side to increase the hydraulic pressure of the wheel cylinders Ba to Bd.
[Pressure mode]
In the pressurizing mode, the pressurizing valves 541A and 541B and the pressure increasing valves 536a to 536d are opened, the pressure reducing valves 538a to 538d and the supply valves 535A and 535B are closed, and the pump motor 540 is operated, whereby the hydraulic pressure of the master cylinder 11 is reached. Regardless, the brake fluid is supplied to the wheel cylinders Ba to Bd by the pumps 539A and 539B.

Various brake controls can be performed by appropriately executing these operation modes according to the vehicle state. For example, braking force distribution control that appropriately distributes the braking force to each wheel according to the ground load during braking, anti-lock brake control that automatically adjusts the braking force of each wheel during braking to prevent wheel locking, A vehicle that stabilizes the behavior of the vehicle by suppressing understeer and oversteer by detecting a skid of a running wheel and automatically automatically applying a braking force to each wheel regardless of the operation amount of the brake pedal PB. Stability control, slope start assist control that keeps braking on hills (especially uphill) and assists in starting, traction control that prevents wheels from slipping when starting, etc., maintains constant distance from the preceding vehicle Vehicle follow-up control, lane departure avoidance control for holding a traveling lane, obstacle avoidance control for avoiding a collision with an obstacle, and the like can be executed.

  As the pumps 539A and 539B, for example, a known hydraulic pump such as a plunger pump, a trochoid pump, or a gear pump can be used. However, considering the on-board performance, quietness, pump efficiency, and the like, it is desirable to use a gear pump. As the pump motor 540, for example, a known motor such as a DC motor, a DC brushless motor, or an AC motor can be used. However, a DC brushless motor is preferable from the viewpoint of controllability, silence, durability, vehicle-mounting property, and the like.

  Further, the characteristics of the electromagnetic on-off valve of the hydraulic pressure control device 500 can be appropriately set according to the usage mode. However, the supply valves 535A and 535B and the pressure increasing valves 536a to 536d are normally opened valves, and the pressure reducing valves 538a to 538d. Since the pressurizing valves 541A and 541B are normally closed valves, the hydraulic pressure can be supplied from the master cylinder 12 to the brake devices Ba to Bd when there is no control signal from the controller 700. Such a configuration is desirable from the viewpoint of efficiency.

  The regenerative braking device 800 collects kinetic energy as electric power by driving a generator (electric motor) by rotation of at least one wheel during deceleration and braking. In the brake system 200 of the present embodiment, the regenerative brake device 800 and the controller 700 exchange control signals with each other, and regenerative braking based on a signal from the stroke sensor SS generated by the driver operating the brake pedal PB. In some cases, regenerative cooperative control for obtaining a desired braking force is executed by supplying a brake fluid pressure obtained by reducing the regenerative braking amount to the wheel cylinders Ba to Bd.

“First Embodiment”
The master cylinder of the first embodiment will be described with reference to FIG. The master cylinder 11 is provided with a reservoir 12 for supplying and discharging hydraulic fluid as hydraulic fluid on the upper side in the vertical direction. In the first embodiment, the reservoir 12 is directly attached to the master cylinder 11, but the reservoir 12 may be arranged at a position separated from the master cylinder 11 and connected by piping.

  The master cylinder 11 has a bottomed cylinder, a cylindrical portion 14 extending in the axial direction from the peripheral portion of the bottom portion 13, and an opening 15 on the opposite side to the bottom portion 13 of the cylindrical portion 14. The cylinder body 16 is formed by processing from the above. The cylinder body 16 is introduced with hydraulic fluid from the reservoir 12 and is mounted on the vehicle in a posture in which the longitudinal direction is along the vehicle front-rear direction. On the inner periphery of the cylinder body 16, in order from the bottom 13 side, a large-diameter inner diameter portion 18, a smaller-diameter sliding inner-diameter portion 19, a larger-diameter inner diameter portion 20 having the same diameter as the larger-diameter inner-diameter portion 18, and a sliding inner-diameter A sliding inner diameter portion 21 having the same diameter as the portion 19 is formed. The large-diameter inner diameter portions 18 and 20 and the sliding inner diameter portions 19 and 21 have a circular cross section perpendicular to the axis of the cylinder portion 14 of the cylinder body 16 (hereinafter referred to as the cylinder axis).

  A primary piston 23 (hydraulic piston) is slidably inserted into the cylinder body 16 at an intermediate position in the cylinder axial direction, and the secondary piston 24 is slidable closer to the bottom 13 than the primary piston 23. Has been inserted. A reaction force piston 25 is partially inserted into the cylinder body 16 on the opening 15 side of the primary piston 23. The secondary piston 24, the primary piston 23, and the reaction force piston 25 are concentrically provided in series in the cylinder axial direction. The secondary piston 24 is slidably fitted to the sliding inner diameter portion 19 on the bottom 13 side, and the primary piston 23 and the reaction force piston 25 are slidable on the sliding inner diameter portion 21 on the opening 15 side. It is mated.

  The primary piston 23 has inner circumferential holes 27 and 28 each having a bottom surface formed on both axial sides, and the secondary piston 24 has inner circumferential holes 29 and 30 each having a bottom surface formed on both axial sides. The master cylinder 11 is a so-called plunger type. Also, the reaction force piston 25 is formed with inner peripheral holes 31 and 32 having bottom surfaces on both sides in the axial direction.

  Mounting portions 34 and 35 projecting outward in the radial direction of the cylindrical portion 14 (hereinafter referred to as cylinder radial direction) are shifted in the cylinder body 16 in the circumferential direction of the cylindrical portion 14 (hereinafter referred to as cylinder axial direction). , Referred to as the cylinder circumferential direction). The mounting base 35 on the opening 15 side is formed longer in the cylinder axial direction than the mounting base 34 on the bottom 13 side. In order to attach the reservoir 12, an attachment hole 36 is formed in the attachment base portion 34, and an attachment hole 37 is formed in the attachment base portion 35 on the attachment base portion 34 side. Here, the mounting holes 36 and 37 are formed in a state in which the positions in the cylinder circumferential direction coincide with each other.

  A secondary discharge passage 39 and a primary discharge passage 40, to which brake pipes for supplying hydraulic fluid to the wheel cylinders Ba to Bd, are respectively attached to the mounting base portions 34 and 35 of the cylinder portion 14 of the cylinder body 16, are in the cylinder axial direction. The positions are shifted from each other. The secondary discharge path 39 is formed closer to the bottom 13 than the primary discharge path 40.

  The sliding inner diameter portion 19 on the bottom 13 side of the cylinder body 16 is formed with an annular seal groove 42 and a seal groove 43 in this order from the bottom 13 side by shifting the position in the cylinder axial direction. In the sliding inner diameter portion 21 on the opening 15 side of the cylinder main body 16, the seal groove 44, the seal groove 45, the seal groove 46, A seal groove 47 is formed in this order from the bottom 13 side. These seal grooves 42 to 47 have an annular shape in the cylinder circumferential direction and are recessed outward in the cylinder radial direction, and all are formed by cutting.

  The seal groove 42 on the most bottom 13 side is formed in the vicinity of the mounting hole 36 on the bottom 13 side, and an annular cup seal 50 is disposed in the seal groove 42.

  In the cylinder main body 16, the cylindrical portion is formed such that a communication hole 51 formed from the mounting hole 36 on the bottom portion 13 side is opened in the cylindrical portion 14 on the opening portion 15 side of the sliding inner diameter portion 19 of the cylinder body 16. An annular opening groove 52 that is recessed outward from the sliding inner diameter portion 19 of the cylinder in the cylinder radial direction is formed. Here, the opening groove 52 and the communication hole 51 mainly constitute a secondary supply path 53 that connects the cylinder body 16 and the reservoir 12 in a communicable manner and always communicates with the reservoir 12.

  The sliding inner diameter portion 19 of the cylinder body 16 has a communication groove 54 that opens into the seal groove 42 and extends linearly from the seal groove 42 toward the bottom portion 13 toward the large diameter inner diameter portion 18 in the cylinder axial direction. It is formed so as to be recessed outward in the cylinder radial direction. The communication groove 54 always communicates the secondary pressure chamber 55 between the secondary piston 24 and the bottom 13 side of the cylinder body 16 and the seal groove 42.

  In the sliding inner diameter portion 19 of the cylinder body 16, the seal groove 43 is formed on the opposite side to the seal groove 42 of the opening groove 52 in the cylinder axial direction, and an annular shape is formed in the seal groove 43. A compartment seal 57 is disposed. The partition seal 57 slidably supports the secondary piston 24 with the sliding inner diameter portion 19 and the cup seal 50, and always seals the gap between the cylinder body 16 and the secondary piston 24.

  On the bottom 13 side of the sliding inner diameter portion 21 of the cylinder body 16, the above-described seal groove 44 is formed in the vicinity of the mounting hole 37 on the opening 15 side. An annular cup seal 60 is disposed in the seal groove 44 so as to be held in the seal groove 44.

  On the opening 15 side of the seal groove 44 in the sliding inner diameter portion 21 of the cylinder body 16, the communication hole 61 formed from the mounting hole 37 on the opening 15 side is opened in the cylinder portion 14. An annular opening groove 62 is formed that is recessed outward from the sliding inner diameter portion 21 of the portion 14 in the cylinder radial direction. Here, the opening groove 62 and the communication hole 61 mainly constitute a primary supply path 63 that connects the cylinder body 16 and the reservoir 12 in a communicable manner and always communicates with the reservoir 12.

  The position of the large-diameter inner diameter portion 20 that opens to the seal groove 44 and linearly extends from the seal groove 44 toward the bottom portion 13 in the cylinder axial direction on the bottom 13 side of the seal groove 44 in the sliding inner diameter portion 21 of the cylinder body 16. A communication groove 64 extending to the outside is formed so as to be recessed outward in the cylinder radial direction. The communication groove 64 allows the primary pressure chamber (pressure chamber) 65 and the seal groove 44 between the primary piston 23 and the secondary piston 24 and the cylinder portion 14 of the cylinder body 16 to always communicate with each other.

  A seal groove 45 is formed on the sliding inner diameter portion 21 of the cylinder body 16 on the opposite side to the seal groove 44 of the opening groove 62, and an annular partition seal 67 is disposed in the seal groove 45. The partition seal 67 slidably supports the primary piston 23 with the sliding inner diameter portion 21 and the cup seal 60, and always seals the gap between the cylinder body 16 and the primary piston 23.

  The above-described seal groove 46 is formed on the opening 15 side of the sliding inner diameter portion 21 of the cylinder body 16. An annular cup seal (seal member) 70 is disposed in the seal groove 46 so as to be held in the seal groove 46.

  On the opening 15 side of the seal groove 46 in the sliding inner diameter portion 21 of the cylinder body 16, a cylinder portion is formed so that a liquid passage 71 extending from the mounting hole 37 on the opening 15 side is opened in the cylinder portion 14. An annular opening groove 72 is formed that is recessed from the 14 sliding inner diameter portions 21 to the outside in the cylinder radial direction.

  Here, the liquid passage 71 has a linear passage hole 74 formed in the mounting base 35 along the cylinder axial direction so as to open in the attachment hole 37, and an opening groove 72. A straight passage hole 75 formed perpendicular to the passage hole 74, a ball 76 for sealing the passage hole 75 outside the passage hole 75, and a passage hole 75 outside the passage hole 74 are sealed. And a ball 77 to be stopped. The passage hole 75 has a stepped shape in which the opening side to the passage hole 74 is a large diameter hole 78 and the opening side to the opening groove 72 is an orifice 79 having a smaller diameter than the large diameter hole 78. The passage hole 74 and the mounting hole 37 constitute a communication passage 81 that communicates the reaction force liquid chamber 80 formed by the primary piston 23 and the reaction force piston 25 and the cylindrical portion 14 of the cylinder body 16 and the reservoir 12. Yes. In the communication path 81, the orifice 79 has the smallest diameter and the flow path cross-sectional area is the smallest.

  In the sliding inner diameter portion 21 of the cylinder body 16, the bottom groove 13 side of the seal groove 46 opens to the seal groove 46 and extends linearly from the seal groove 46 in the cylinder axial direction toward the bottom portion 13 side by a predetermined length. The groove 82 is formed so as to be recessed outward in the cylinder radial direction. The communication groove 82 always communicates the reaction force liquid chamber 80 and the seal groove 46.

  A seal groove 47 is formed on the sliding inner diameter portion 21 of the cylinder body 16 on the opposite side to the seal groove 46 of the opening groove 72, and an annular partition seal 83 is disposed in the seal groove 47. The partition seal 83 slidably supports the reaction force piston 25 with the sliding inner diameter portion 21 and the cup seal 70, and always seals the gap between the cylinder body 16 and the reaction force piston 25.

  The secondary piston 24 has a shape having a cylindrical portion 86 and a bottom portion 87 formed at an intermediate position in the axial direction of the cylindrical portion 86. The inner peripheral holes 29 and 30 are formed by the cylindrical portion 86 and the bottom portion 87. The secondary piston 24 slides on the inner periphery of each of the cup seal 50 and the partition seal 57 provided on the sliding inner diameter portion 19 of the cylinder body 16 with the inner peripheral hole 29 disposed on the bottom 13 side of the cylinder body 16. It is movably fitted. A plurality of ports 89 penetrating in the cylinder radial direction are formed radially on the inner peripheral hole 29 side in the axial direction of the cylindrical portion 86.

  Between the secondary piston 24 and the bottom portion 13 of the cylinder body 16, there is an interval adjusting portion 93 including a secondary piston spring 92 that determines these intervals in a non-braking state without input from the brake pedal PB side (right side in FIG. 2). Is provided. The gap adjusting portion 93 includes a locking member 94 that contacts the bottom portion 13 of the cylinder body 16, a locking member 95 that is inserted into the inner peripheral hole 29 of the secondary piston 24 and contacts the bottom portion 87, and a locking member 95. One end portion is fixed, and a shaft member 96 that slidably supports the locking member 94 only within a predetermined range is provided. The secondary piston spring 92 is interposed between the locking members 94 and 95 on both sides.

  Here, in the cylinder body 16, a portion defined by the bottom portion 13 and the bottom portion 13 side of the cylindrical portion 14 and the secondary piston 24 generates hydraulic fluid pressure from the secondary discharge passage 39 to the wheel cylinders Bc, Bd. This is the secondary pressure chamber 55 for supplying the hydraulic fluid to the above. The secondary pressure chamber 55 communicates with the secondary supply path 53 when the secondary piston 24 is in a position to open the port 89 into the opening groove 52.

  The cup seal 50 held in the seal groove 42 on the bottom 13 side of the cylinder body 16 has an E-shaped one-side shape in the radial cross section including its center line. The cup seal 50 is configured so that the secondary piston 24 slides on the inner periphery of the sliding inner diameter portion 19, the cup seal 50, and the partition seal 57 of the cylinder body 16 from the non-braking position in the non-braking state. When the port 89 is positioned at the bottom 13 side of the cup seal 50 by moving at least the stroke S1 to the side, it is possible to seal between the secondary supply passage 53 and the secondary pressure chamber 55 that have been communicating with each other until the port 89. That is, communication between the secondary pressure chamber 55 and the secondary supply path 53 and the reservoir 12 can be blocked. That is, this stroke S1 is an invalid stroke at the beginning of braking in which the secondary piston 24 does not supply hydraulic fluid to the wheel cylinders Bc, Bd, in other words, does not increase the hydraulic pressure of the wheel cylinders Bc, Bd.

  The secondary piston 24 further pressurizes the hydraulic fluid in the secondary pressure chamber 55 by moving further to the bottom 13 side with the port 89 positioned on the bottom 13 side than the cup seal 50 as described above. Thus, the secondary discharge passage 39 is supplied to the wheel cylinders Bc and Bd. In the cup seal 50, when the pressure in the secondary pressure chamber 55 becomes lower than the pressure (atmospheric pressure) in the secondary supply path 53 and the reservoir 12, the hydraulic fluid passes through the seal groove 42 and the communication groove 54, and the hydraulic fluid passes through the secondary supply path 53. To the secondary pressure chamber 55.

  The primary piston 23 has a shape having a cylindrical portion 99 and a bottom portion 100 formed at an intermediate position in the axial direction of the cylindrical portion 99. The inner peripheral holes 27 and 28 are formed by the cylindrical portion 99 and the bottom portion 100. The primary piston 23 has inner circumferential holes 27 arranged on the side of the secondary piston 24 in the cylinder body 16, and each inner circumference of the cup seal 60 and the partition seal 67 provided on the sliding inner diameter portion 21 of the cylinder body 16. It is slidably fitted to. On the inner peripheral hole 27 side in the axial direction of the cylindrical portion 99, a plurality of ports 102 penetrating in the radial direction are formed radially.

  Between the secondary piston 24 and the primary piston 23, there is provided an interval adjusting unit 106 including a primary piston spring 105 that determines these intervals in a non-braking state without input from the brake pedal PB side (right side in FIG. 2). Yes. The interval adjusting unit 106 is inserted into the inner peripheral hole 30 of the secondary piston 24 and contacts the bottom 87, and the locking member is inserted into the inner peripheral hole 27 of the primary piston 23 and contacts the bottom 100. 108 and a shaft member 109 that has one end fixed to the locking member 108 and supports the locking member 107 slidably only within a predetermined range. The primary piston spring 105 is interposed between the locking members 107 and 108 on both sides.

  Here, a portion defined by the cylindrical portion 14, the primary piston 23, and the secondary piston 24 in the cylinder body 16 generates a hydraulic fluid pressure, and the hydraulic fluid is transferred from the primary discharge path 40 to the wheel cylinders Ba and Bb. The primary pressure chamber 65 is supplied as described above. The primary pressure chamber 65 communicates with the primary supply path 63 when the primary piston 23 is in a position where the port 102 is opened to the opening groove 62.

  Similarly to the cup seal 50, the cup seal 60 held in the seal groove 44 of the cylinder body 16 has an E-shaped one-side shape in a radial cross section including its center line. When the cup seal 60 moves at least the stroke S1 from the non-braking position in which the primary piston 23 is in the non-braking state to the bottom 13 side to position the port 102 closer to the bottom 13 than the cup seal 60, the port 102 until then. It is possible to seal between the primary supply path 63 and the primary pressure chamber 65 that have been communicated via the primary pressure chamber 65, that is, communication between the primary pressure chamber 65, the primary supply path 63, and the reservoir 12 can be blocked. That is, the stroke S1 is an invalid stroke that does not supply hydraulic fluid to the wheel cylinders Ba and Bb in the primary piston 23, in other words, does not increase the hydraulic pressure of the wheel cylinders Ba and Bb. The length is the same as the invalid stroke. In other words, the primary piston 23 and the secondary piston 24 simultaneously close the port 102 and the port 89 with the same invalid stroke.

  The primary piston 23 pressurizes the hydraulic fluid in the primary pressure chamber 65 by further moving to the bottom 13 side with the port 102 positioned on the bottom 13 side of the cup seal 60 as described above. Thus, it is supplied from the primary discharge passage 40 to the wheel cylinders Ba and Bb. When the pressure in the primary pressure chamber 65 becomes lower than the pressure in the primary replenishment path 63, that is, the reservoir 12 (atmospheric pressure), the cup seal 60 is supplied with hydraulic fluid via the seal groove 44 and the communication groove 64. To the primary pressure chamber 65.

  The reaction force piston 25 applies a reaction force to the brake pedal PB via the booster 201, and has a shape having a cylindrical portion 112 and a bottom portion 113 formed at an intermediate position in the axial direction of the cylindrical portion 112. There is no. The inner peripheral holes 31 and 32 are formed by the cylindrical portion 112 and the bottom portion 113. The reaction force piston 25 is disposed in the inner portion of the cup seal 70 and the partition seal 83 provided in the sliding inner diameter portion 21 of the cylinder body 16 in a state where the inner peripheral hole 31 is disposed on the primary piston 23 side in the cylinder body 16. The periphery is slidably fitted. A plurality of radially extending ports 115 are formed radially on the inner peripheral hole 31 side in the axial direction of the cylindrical portion 112. Here, the output shaft of the booster 201 is inserted inside the inner peripheral hole 32, and the bottom 113 of the reaction force piston 25 is pressed by this output shaft.

  Between the primary piston 23 and the reaction force piston 25, a reaction force spring that determines the distance in cooperation with the booster 201 in a non-braking state without input from the brake pedal PB side (right side in FIG. 2). An interval adjusting unit 119 including 118 is provided. The gap adjusting portion 119 is inserted into the inner peripheral hole 31 of the primary piston 23 and is engaged with the shaft member 120 and is inserted into the inner peripheral hole 31 of the reaction force piston 25. And a locking member 121 that contacts the bottom portion 113. The locking member 121 is movable with respect to the shaft member 120 only within a predetermined range. The reaction force spring 118 is interposed between the bottom 100 of the primary piston 23 and the locking member 121.

  Here, a portion defined by the opening 15 side of the cylindrical portion 14, the primary piston 23, and the reaction force piston 25 in the cylinder body 16 is the reaction force liquid chamber 80 described above. Therefore, the reaction force spring 118 is disposed in the reaction force liquid chamber 80 formed between the reaction force piston 25 and the primary piston 23. The reaction force liquid chamber 80 communicates with the communication passage 81 when the reaction force piston 25 is in a position to open the port 115 into the opening groove 72. The reaction force spring 118 is set so that the cylindrical portion 112 of the reaction force piston 25 can be brought into contact with the cylindrical portion 99 of the primary piston 23 by depressing the brake pedal PB. That is, at the time of non-braking, the reaction force piston 25 and the primary piston 23 are separated from each other by the interval adjusting unit 119, and when the reaction force piston 25 moves by a predetermined amount from the position at the time of non-braking, it comes into contact with the primary piston 23. This can be pressed.

  As with the cup seals 50 and 60, the cup seal 70 held in the seal groove 46 of the cylinder body 16 also has an E-shaped one-side shape in the radial cross section including its center line. The cup seal 70 can seal between the communication path 81 and the reaction force liquid chamber 80 in a state where the reaction force piston 25 positions the port 115 on the bottom 13 side of the cup seal 70. Communication between the chamber 80 and the reservoir 12 can be blocked. In other words, the cup seal 70 blocks the communication between the communication path 81 and the reaction force liquid chamber 25 as the reaction force piston 25 moves with respect to the cylinder body 16, and allows the reaction fluid in the reaction force liquid chamber 80 to flow. Confine. The communication path 81 provided with an orifice 79 is operated by the cup seal 70 until the communication path 81 and the reaction force liquid chamber 80 are disconnected from the communication state. The liquid is moved to the reservoir 12. The distance S2 from when the reaction force piston 25 moves from the non-braking position until the port 115 is closed by the cup seal 70 is equal to the primary piston 23 in which the reaction force piston 25 moves from the non-braking position and is at the non-braking position. It is equal to distance S3 until it contacts. In the cup seal 70, when the pressure of the reaction force liquid chamber 80 becomes lower than the pressure (atmospheric pressure) of the communication path 81, that is, the reservoir 12, the hydraulic fluid is returned from the communication path 81 via the seal groove 46 and the communication groove 82. It is allowed to flow into the hydraulic fluid chamber 80.

  Next, the operation of the master cylinder 11 of the first embodiment will be described.

  FIG. 2 shows a state in which the reaction force piston 25, the primary piston 23, and the secondary piston 24 are not braked when there is no input to the brake pedal PB. In the non-braking position at the time of non-braking, the reaction force piston 25 communicates the communication path 81 and the reaction force liquid chamber 80 through the port 115, and as a result, the reaction force liquid chamber 80 communicates with the reservoir 12. Yes. In the non-braking position at the time of non-braking described above, the primary piston 23 communicates the primary replenishment path 63 and the primary pressure chamber 65 through the port 102, and as a result, communicates the primary pressure chamber 65 to the reservoir 12. ing. Furthermore, in the non-braking position at the time of non-braking described above, the secondary piston 24 communicates the secondary supply path 53 and the secondary pressure chamber 55 via the port 89, and as a result, communicates the secondary pressure chamber 55 to the reservoir 12. ing.

  When there is an operation input to the brake pedal PB from such a non-braking state, the booster 201 presses the reaction force piston 25 toward the bottom 13 of the cylinder body 16 by this input. At this time, the reaction force piston 25 contracts the reaction force spring 118 of the interval adjusting unit 119 while the reaction force piston 25 contracts during the slow braking when the operation input of the brake pedal PB is the slow operation and during the normal braking which is the normal operation. Even if it moves to the 80 side, the flow rate of the working fluid flowing from the reaction force fluid chamber 80 through the communication passage 81 having the orifice 79 is small, so that the working fluid in the reaction force fluid chamber 80 smoothly flows from the communication passage 81 to the reservoir 12. The reaction pressure fluid chamber 80 does not increase in hydraulic pressure, and the primary piston 23 and the secondary piston 24 do not move. The reaction force piston 25 moves the stroke S2 (= S3) until the port 115 is closed by the cup seal 70, and then comes into contact with and presses the primary piston 23.

  Then, in the non-braking position, the primary piston 23 that communicated the primary pressure chamber 65 to the reservoir 12 by the port 102 and the secondary piston 24 that communicated the secondary pressure chamber 55 to the reservoir 12 by the port 89, The stroke S <b> 1 described above is moved while the secondary piston spring 92 of the interval adjusting unit 93 is compressed and contracted integrally by the urging force of the interval adjusting unit 106. Then, the port 102 of the primary piston 23 is closed by the cup seal 60, and at the same time, the port 89 of the secondary piston 24 is closed by the cup seal 50. Then, the primary piston 23 and the secondary piston 24 further move to the bottom 13 side. Then, the primary piston 23 supplies the hydraulic fluid from the primary pressure chamber 65 to the wheel cylinders Ba and Bb via the primary discharge path 40, and at the same time, the secondary piston 24 moves from the secondary pressure chamber 55 to the wheel cylinder Bc via the secondary discharge path 39. , Bd is supplied with hydraulic fluid. Thus, the invalid stroke at the time of slow braking and normal braking is S1 + S2 (= S1 + S3).

  On the other hand, at the time of sudden braking in which the operation input of the brake pedal PB is a sudden operation, the reaction force piston 25 reacts while contracting the reaction force spring 118 of the interval adjusting unit 119 at a speed higher than that at the time of slow braking and normal braking. It moves to the hydraulic fluid chamber 80 side.

  Then, since the flow rate of the working fluid flowing from the reaction force fluid chamber 80 through the communication passage 81 having the orifice 79 is increased, the working fluid is restricted by the orifice 79 and cannot flow to the reservoir 12 side. The reaction force liquid chamber 80 is substantially enclosed, and the liquid pressure in the reaction force liquid chamber 80 is increased. Thus, before the reaction force piston 25 contacts the primary piston 23, that is, before moving the stroke S2 (= S3), the primary pressure chamber 65 is communicated with the reservoir 12 by the port 102 in the non-braking position. The primary piston 23 and the secondary piston 24 having the secondary pressure chamber 55 communicating with the reservoir 12 by the port 89 are integrally compressed by the urging force of the interval adjusting unit 106 to contract the secondary piston spring 92 of the interval adjusting unit 93. However, the stroke S1 described above is moved. Then, in the same manner as described above, the hydraulic fluid is supplied from the primary pressure chamber 65 to the wheel cylinders Ba and Bb, and at the same time, the hydraulic fluid is supplied from the secondary pressure chamber 55 to the wheel cylinders Bc and Bd.

  That is, the reaction force piston 25, the primary piston 23, and the secondary piston 24 move in a state where there is a gap between the reaction force piston 25 and the primary piston 23, and the substantial invalid stroke is the above-described S1 + S2 ( = S1 + S3). The master cylinder 11 is of an invalid stroke simultaneous closing type that closes the port 102 of the primary piston 23 and the port 89 of the secondary piston 24 with the same invalid stroke as described above.

  According to the master cylinder 11 of the first embodiment described above, the orifice 79 is provided in the communication passage 81 that communicates between the reaction force liquid chamber 80 between the reaction force piston 25 and the primary piston 23 and the reservoir 12. ing. For this reason, at the time of slow braking and normal braking, the working fluid in the reaction force fluid chamber 80 can be released (flowed out) to the reservoir 12 through the orifice 79, and the reaction force piston 25 can be moved away from the non-braking position. The stroke until the fixed amount S3 is moved to abut against the primary piston 23 can be set as an invalid stroke. In addition, the hydraulic fluid in the reaction force liquid chamber 80 cannot escape to the reservoir 12 through the orifice 79 during sudden braking, and the reaction force piston 25 comes into contact with the primary piston 23 from the non-braking position. Previously, the primary piston 23 is pressed with the hydraulic pressure of the reaction force liquid chamber 80 to end the invalid stroke. Therefore, at the time of slow braking and normal braking, the invalid stroke can be lengthened to contribute to the improvement of the regeneration efficiency. In addition, at the time of sudden braking, the invalid stroke can be shortened to prevent the invalid stroke from becoming longer.

“Second Embodiment”
Next, the master cylinder according to the second embodiment will be described mainly on the difference from the first embodiment based on FIG. In addition, about the site | part which is common in 1st Embodiment, it represents with the same name and the same code | symbol.

  In the second embodiment, a liquid passage 71 and a mounting hole 37 that constitute a communication passage 81 communicating between the reaction force liquid chamber 80 and the reservoir 12 are different from those in the first embodiment. The liquid passage 71 is not provided with the orifice 79 of the first embodiment. The liquid passage 71 includes a passage hole 74 along the cylinder axial direction similar to that in the first embodiment and a ball 76 that seals the opening end of the passage hole 74, and an opening groove 72 and a passage unlike the first embodiment. An arc-shaped communication groove 131 formed in the cylinder radial direction from the opening groove 72 side is provided so as to communicate with the hole 74.

  In addition, a valve mechanism 133 including a check valve that is opened when hydraulic fluid is supplied from the reservoir 12 to the primary pressure chamber 65 and the reaction force fluid chamber 80 is provided in the mounting hole 37 constituting the communication passage 81. The valve mechanism 133 includes a base member 134 that is fitted into the mounting hole 37, an elastically deformable annular valve plate 135 that is attached with the inner peripheral edge locked to the communication hole 61 side of the base member 134, A retaining ring 136 that is locked to the mounting hole 37 on the side opposite to the valve plate 135 of the base member 134 and an O-ring 137 that seals a gap between the base member 134 and the mounting hole 37 are provided.

  In the base member 134, a plurality of passage holes 138 are formed along the axial direction at positions that can be opened and closed by the valve plate 135, and an orifice 139 is formed at a central position that is not blocked by the valve plate 135. When the hydraulic pressure on the primary pressure chamber 65 side and the reaction force liquid chamber 80 side is lower than the hydraulic pressure on the reservoir 12 side, which is atmospheric pressure, the valve mechanism 133 elastically deforms the valve plate 135 to open the passage hole 138, Liquid is supplied from the reservoir 12 together with the orifice 139. Only at this time, the passage hole 138 forms the communication passage 81. On the other hand, the orifice 139 always constitutes the communication path 81. In a state where the passage hole 138 is closed by the valve plate 135, the orifice 139 has the smallest diameter in the communication passage 81 and the flow passage cross-sectional area is the smallest.

  Such a master cylinder 11 of the second embodiment also operates in the same manner as in the first embodiment. That is, the hydraulic fluid flowing from the reaction force fluid chamber 80 to the communication passage 81 smoothly flows through the orifice 139 during the slow braking when the operation input of the brake pedal PB is the slow operation and during the normal braking which is the normal operation. The invalid stroke is S1 + S2 (= S1 + S3). On the other hand, at the time of sudden braking in which the operation input of the brake pedal PB is a sudden operation, the orifice 139 inhibits the flow of hydraulic fluid flowing from the reaction force liquid chamber 80 to the communication path 81, and the hydraulic pressure of the reaction force liquid chamber 80 is reduced. Therefore, the invalid stroke becomes shorter than S1 + S2 (= S1 + S3). This master cylinder 11 is also of an invalid stroke simultaneous closing type.

  As described above, according to the second embodiment, it is possible to lengthen the invalid stroke at the time of slow braking and normal braking to contribute to the improvement of the regeneration efficiency. In addition, at the time of sudden braking, the invalid stroke is shortened to prevent the lengthening of the stroke. It will be possible.

“Third Embodiment”
Next, the master cylinder according to the third embodiment will be described mainly on the difference from the first embodiment based on FIG. In addition, about the site | part which is common in 1st Embodiment, it represents with the same name and the same code | symbol.

  In the third embodiment, the communication path 81 of the first embodiment that communicates between the reaction force liquid chamber 80 and the reservoir 12 is not provided. Instead, a communication passage 141 that communicates between the reaction force liquid chamber 80 and the primary pressure chamber 65 is formed in the bottom 100 of the primary piston 23. This communication passage 141 is formed by a passage hole 142 formed in the center of the bottom 100 of the primary piston 23. The passage hole 142 has a stepped shape in which the opening side to the reaction force liquid chamber 80 is a large diameter hole 143 and the opening side to the primary pressure chamber 65 is an orifice 144 having a smaller diameter than the large diameter hole 143. ing. In this communication path 141, the orifice 144 has the smallest diameter and the flow path cross-sectional area is the smallest.

  Accordingly, the seal groove 46, the opening groove 72, the communication groove 82, and the cup seal 70 of the first embodiment are not provided. Further, the cylindrical portion 112 of the reaction force piston 25 does not protrude from the bottom 113 to the primary piston 23 side, and the port 115 of the first embodiment is not provided. A protrusion 145 that protrudes toward the primary piston 23 is formed at the center of the bottom 113 of the reaction force piston 25. A reaction force spring 118 is interposed between the bottom 113 of the reaction force piston 25 and the bottom 100 of the primary piston 23 with the protrusion 145 fitted inside.

  Next, the operation of the master cylinder 11 of the third embodiment will be described.

  There is an operation input to the brake pedal PB from the same non-braking state as in the first embodiment, and the booster 201 presses the reaction force piston 25 toward the bottom 13 of the cylinder body 16 by this input. At this time, the reaction force piston 25 moves to the reaction force liquid chamber 80 side while contracting the reaction force spring 118 at the time of slow braking when the operation input of the brake pedal PB is slow operation and during normal braking as the normal operation. However, since the flow rate of the working fluid flowing from the reaction force fluid chamber 80 through the communication passage 141 having the orifice 144 is small, the working fluid smoothly flows from the communication passage 141 to the primary pressure chamber 65 side, and the reaction force fluid chamber 80 Fluid pressure does not increase. Further, the hydraulic fluid that has flowed to the primary pressure chamber 65 side is discharged from the port 102 of the primary piston 23 in the non-braking position to the reservoir 12 via the primary supply path 63, and the primary piston 23 is in the non-braking position. Maintained. Then, the reaction force piston 25 moves from the non-braking position and moves a distance S3 until it comes into contact with the primary piston 23 in the non-braking position, and comes into contact with the primary piston 23 to press it.

  Then, similarly to the first embodiment, the primary piston 23 and the secondary piston 24 integrally move the stroke S1 described above, and from the primary pressure chamber 65 to the wheel cylinders Ba and Bb via the primary discharge passage 40, The hydraulic fluid is supplied from the secondary pressure chamber 55 to the wheel cylinders Bc and Bd through the secondary discharge passage 39, respectively. The invalid stroke at this time is S1 + S3.

  On the other hand, at the time of sudden braking in which the operation input of the brake pedal PB is sudden operation, the reaction force fluid chamber 80 is contracted while the reaction force piston 25 contracts the reaction force spring 118 of the interval adjusting unit 119 at a speed faster than that at the time of normal braking. Will move to the side. Then, since the flow rate of the working fluid flowing from the reaction force fluid chamber 80 through the communication path 141 having the orifice 144 is large, the working fluid is restricted by the orifice 144 and cannot flow to the primary pressure chamber 65 side. The liquid pressure in the reaction liquid chamber 80 is increased by being substantially enclosed in the liquid chamber 80. Thereby, before the reaction force piston 25 abuts on the primary piston 23, that is, before moving the stroke S3, the primary piston 23 and the secondary piston 24 which are in the non-braking position move together the stroke S1 described above. Then, the hydraulic fluid is supplied from the primary pressure chamber 65 to the wheel cylinders Ba and Bb via the primary discharge passage 40 and from the secondary pressure chamber 55 to the wheel cylinders Bc and Bd via the secondary discharge passage 39. The invalid stroke at this time is shorter than S1 + S3 described above. This master cylinder 11 is also of an invalid stroke simultaneous closing type.

  According to the master cylinder 11 of the third embodiment described above, the orifice 144 is provided in the communication passage 141 communicating between the reaction force liquid chamber 80 and the primary pressure chamber 65 between the reaction force piston 25 and the primary piston 23. Was established. For this reason, at the time of slow braking and normal braking, the working fluid in the reaction force fluid chamber 80 can be released to the reservoir 12 via the primary pressure chamber 65 via the orifice 144, and the reaction force piston 25 can be The stroke until the predetermined amount S3 is moved from the position and abuts against the primary piston 23 can be made an invalid stroke. During sudden braking, the hydraulic fluid in the reaction force fluid chamber 80 cannot be released to the primary pressure chamber 65 via the orifice 144, and the reaction force piston 25 is allowed to react before moving the predetermined amount S3 from the non-braking position. The primary piston 23 is pressed by the hydraulic pressure in the hydraulic fluid chamber 80 to move the primary piston 23 and the invalid stroke is completed. Therefore, at the time of slow braking and normal braking, the invalid stroke can be lengthened to contribute to the improvement of the regeneration efficiency. In addition, at the time of sudden braking, the invalid stroke can be shortened to prevent the lengthening thereof.

  In addition, the number of parts and processing locations can be reduced, and the cost can be reduced.

“Fourth Embodiment”
Next, the master cylinder according to the fourth embodiment will be described mainly on the difference from the third embodiment based on FIG. In addition, about the site | part which is common in 3rd Embodiment, it represents with the same name and the same code | symbol.

  In the fourth embodiment, the reaction force piston 25 is provided in the primary piston 23. Further, the partition seal 67 of the third embodiment for supporting the primary piston 23 on the cylinder body 16 in a sealed state and the seal groove 45 for holding it are not provided. Instead, the partition seal 83 and the seal are held. A sealing groove 47 is provided on the opening 15 side in the vicinity of the opening groove 62. Further, the axial length of the cylinder body 16 is shortened by the amount that the reaction force piston 25 and the primary piston 23 overlap in the axial direction.

  In the reaction force piston 25 of the fourth embodiment, the cylindrical portion 112 extends to both sides in the axial direction of the bottom portion 113, and a reaction force spring 118 is inserted into the inner peripheral hole 31 on the primary piston 23 side. An annular groove 151 is formed in a predetermined axial intermediate range on the outer peripheral side of the cylindrical portion 112, and a plurality of communication holes 152 that open to the inner peripheral hole 31 are formed radially on the primary piston 23 side of the groove 151. ing. An annular seal groove 153 that is deeper than the groove 151 is formed on the inner peripheral hole 32 side of the groove 151, and the seal groove 153 is a section that seals the gap between the reaction force piston 25 and the primary piston 23. A seal 154 is provided. A stopper 155 for preventing the primary piston 23 and the reaction force piston 25 from coming off is attached to the opening 15 of the cylinder body 16.

  Such a master cylinder 11 of the fourth embodiment also operates in the same manner as in the third embodiment. That is, when the brake pedal PB operation input is a slow operation and the normal operation is a normal operation, the hydraulic fluid in the reaction force liquid chamber 80 between the primary piston 23 and the reaction force piston 25 is changed to a reaction force. Until the piston 25 abuts against the bottom 100 of the primary piston 23, the orifice 144 smoothly flows, and the invalid stroke becomes S1 + S3. On the other hand, at the time of sudden braking in which the operation input of the brake pedal PB is a sudden operation, the orifice 144 inhibits the flow of the working fluid and increases the fluid pressure in the reaction force fluid chamber 80, and the reaction force piston 25. Before the primary piston 23 comes into contact with the bottom 100 of the primary piston 23, the primary piston 23 and the secondary piston 24 start moving, and the invalid stroke becomes shorter than S1 + S3.

  As described above, according to the fourth embodiment, it is possible to contribute to improving the regenerative efficiency by increasing the invalid stroke at the time of slow braking and normal braking. In addition, at the time of sudden braking, the invalid stroke is shortened to prevent the lengthening thereof. It will be possible. In addition, according to the master cylinder 11 of the fourth embodiment, since the reaction force piston 25 is disposed in the primary piston 23, the overall length can be shortened.

“Fifth Embodiment”
Next, the master cylinder according to the fifth embodiment will be described mainly on the difference from the second embodiment based on FIGS. 6 and 7. In addition, about the site | part which is common in 2nd Embodiment, it represents with the same name and the same code | symbol.

  In the fifth embodiment, the reaction force piston 25 of the second embodiment is not provided. Therefore, the output shaft of the booster 201 is inserted inside the inner peripheral hole 28 of the primary piston 23, and this output shaft As a result, the bottom 100 of the primary piston 23 is pressed. In the primary piston 23, the outer diameter side of the cylindrical portion 99 is the small-diameter outer diameter portion 161 on the inner circumferential hole 27 side in the axial direction, and the large-diameter outer diameter portion whose inner circumferential hole 28 side is larger in diameter than the small-diameter outer diameter portion 161. The stepped shape is 162. In addition, an annular annular groove 163 is formed on the small-diameter outer diameter portion 161 side of the large-diameter outer diameter portion 162, and between the annular groove 163 of the large-diameter outer diameter portion 162 and the small-diameter outer diameter portion 161. An axial groove 164 penetrating in the axial direction is formed.

  In accordance with the primary piston 23, the cylinder body 16 also has a large-diameter sliding inner diameter portion 165 having a larger diameter than the sliding inner diameter portion 21 on the opening 15 side, and the sliding inner diameter portion 21 and the large-diameter sliding inner diameter portion 165 are formed. A large-diameter inner diameter portion 166 having a diameter larger than that of the large-diameter sliding inner diameter portion 165 is formed therebetween. The sliding inner diameter portion 21 is not provided with the seal groove 45, the partition seal 67 and the opening groove 62 of the second embodiment, and only the seal groove 44 and the communication groove 64 for holding the cup seal 60 are formed. ing. Further, a seal groove 46, an opening groove 72 and a seal groove 47 are formed in the large-diameter sliding inner diameter portion 165, a cup seal 70 is disposed in the seal groove 46, and a partition seal 83 is disposed in the seal groove 47.

  The primary piston 23 is slidably supported by the sliding inner diameter portion 21 and the cup seal 60 at the small diameter outer diameter portion 161, and the large diameter sliding inner diameter portion 165, the cup seal 70, and the partition seal 83 at the large diameter outer diameter portion 162. Is slidably supported by.

  A large-diameter pressurizing chamber 169 is formed between the large-diameter sliding inner diameter portion 165 and the large-diameter inner diameter portion 166 of the cylinder body 16 and the primary piston 23. The large-diameter pressurizing chamber 169 is provided to introduce more hydraulic fluid into the primary pressure chamber 65 when the primary piston 23 moves to the bottom 13. And the communication hole 61 which comprises the primary replenishment path 63 makes the attachment hole 37 communicate with this large diameter pressurizing chamber 169. That is, the primary supply path 63 allows the reservoir 12 and the primary pressure chamber 65 to communicate with each other via the large-diameter pressurizing chamber 169. In addition, the passage hole 74 of the liquid passage 71 is opened to the reservoir 12 rather than the valve mechanism 133 of the attachment hole 37.

  The cup seal 70 held in the seal groove 46 of the cylinder body 16 is configured so that the liquid passage 71 and the large-diameter pressurizing chamber 169 are formed in an annular groove in a state where the annular groove 163 is positioned on the opening 15 side of the cup seal 70. In the state where the annular groove 163 is positioned on the bottom 13 side with respect to the cup seal 70, the liquid passage 71 and the large diameter pressurizing chamber 169 can be sealed. ing.

  As shown in FIG. 7, the valve mechanism 133 includes a lid member 172 that forms a valve chamber 171 that communicates with the orifice 139 with the base member 134 between the base member 134 and the retaining ring 136, and a lid member 172. A locking member 173 for locking is provided. The lid member 172 is formed with an orifice 174 having a reduced flow path area coaxially with the orifice 139 having a reduced flow path area, and the valve chamber 171 communicates with the reservoir 12 via the orifice 174. A spherical valve body 175 capable of opening and closing the orifice 139 and the orifice 174 is accommodated in the valve chamber 171.

  The valve body 175 is separated from and abuts against the valve seat 176 on the orifice 174 side of the valve chamber 171 in accordance with the flow rate of the hydraulic fluid flowing through the orifice 139 and flowing into the valve chamber 171. That is, if the flow rate of the hydraulic fluid flowing through the orifice 139 and flowing into the valve chamber 171 is slow, the valve body 175 is slightly pushed up by the hydraulic fluid and separated from the valve seat 176, and the orifice 139, the valve chamber The primary supply path 63 including the 176 and the orifice 174 is set in a communication state. On the other hand, if the flow rate of the hydraulic fluid flowing through the orifice 139 and flowing into the valve chamber 171 is high, the valve body 175 is greatly pushed up by the hydraulic fluid and comes into contact with the valve seat 176 as shown in FIG. In this state, the primary supply path 63 is shut off between the valve chamber 176 and the orifice 174. Therefore, the valve body 175 and the valve seat 176 are provided closer to the reservoir 12 than the orifice 139 with a reduced flow path area, and the primary replenishment path 63 is communicated and blocked according to the flow rate of the hydraulic fluid passing through the orifice 139. An on-off valve 177 is configured. In addition, a valve seat 178 that shuts off the communication between the orifice 139 and the valve chamber 71 when the valve body 175 abuts is formed on the orifice 139 side of the valve chamber 71.

  Next, the operation of the master cylinder 11 of the fifth embodiment will be described.

  FIG. 6 shows a state in which the primary piston 23 and the secondary piston 24 are not braked when there is no input to the brake pedal PB. In the non-braking position at the time of non-braking, the primary piston 23 communicates the primary replenishment path 63 with the primary pressure chamber 65 through the large-diameter pressurizing chamber 169 through the port 102, and as a result, the primary pressure chamber 65. Is communicated with the reservoir 12. Further, the large-diameter pressurizing chamber 169 and the reservoir 12 are communicated with each other via the liquid passage 71 by the annular groove 163 and the axial groove 164. In the non-braking position, the secondary piston 24 allows the secondary supply passage 53 and the secondary pressure chamber 55 to communicate with each other through the port 89, as in the second embodiment.

  From this non-braking state, there is an operation input to the brake pedal PB, and the booster 201 presses the bottom 100 of the primary piston 23 toward the bottom 13 of the cylinder body 16 by this input. At this time, the primary piston 23 strokes toward the bottom 13 side while contracting the primary piston spring 105 of the distance adjusting unit 106 at the time of slow braking when the operation input of the brake pedal PB is a slow operation and at the time of normal braking which is a normal operation. By moving S13 and the cup seal 70, the communication between the liquid passage 71 and the large-diameter pressurizing chamber 169 by the annular groove 163 and the axial groove 164 is cut off. The volume of the radial pressurizing chamber 169 is decreased. At this time, the hydraulic fluid in the large-diameter pressurizing chamber 169 flows into the primary supply path 63 and flows through the primary supply path 63 having the orifice 139 while pushing up the valve body 175 of the valve mechanism 133. Since the flow rate of the hydraulic fluid flowing through 139 is small, the hydraulic fluid smoothly flows from the state shown in FIG. 7A toward the reservoir 12 through the orifice 139, the valve chamber 171 and the orifice 174 while pushing up the valve body 175 slightly. . As a result, the hydraulic pressure in the large-diameter pressurizing chamber 169 and the primary pressure chamber 65 does not increase, and the secondary piston 24 does not move. The primary piston 23 moves while the primary piston spring 105 is compressed and contracted during a stroke S12 until the port 102 is closed by the cup seal 60.

  When the primary piston 23 moves in the stroke S12, the port 102 of the primary piston 23 that communicates the primary pressure chamber 65 with the large-diameter pressurizing chamber 169 is closed by the cup seal 60, and the primary piston 23 is further moved to the bottom 13 side. The hydraulic fluid is supplied from the primary pressure chamber 65 to the wheel cylinders Ba and Bb through the primary discharge passage 40. Thus, the cup seal (seal member) 60 communicates between the primary supply passage 63 and the large-diameter pressurizing chamber 169 and the primary pressure chamber 65 as the primary piston 23 moves with respect to the cylinder body 16. And shut off. At this time, the secondary piston 24 that has previously communicated the secondary pressure chamber 55 to the reservoir 12 through the port 89 by the pressure increase in the primary pressure chamber 65 compresses the secondary piston spring 92 of the interval adjustment unit 93. The stroke S11 is moved. Then, the port 89 of the secondary piston 24 is closed by the cup seal 50, and the secondary piston 24 further moves to the bottom 13 side, so that the hydraulic fluid is transferred from the secondary pressure chamber 55 to the wheel cylinders Bc and Bd via the secondary discharge passage 39. Supply. The invalid stroke at this time is S11 + S12 + S13. (S12> S11 = S13)

  On the other hand, at the time of sudden braking in which the operation input of the brake pedal PB is sudden operation, the primary piston 23 moves to the bottom 13 side while pushing and contracting the primary piston spring 105 at a faster speed than that at the time of normal braking. Then, the primary piston 23 moves the stroke S13 to the bottom 13 side, and the cup seal 70 blocks communication between the liquid passage 71 and the large-diameter pressurizing chamber 169 by the annular groove 163 and the axial groove 164. Then, it further moves to the bottom 13 side, and the volume of the large-diameter pressurizing chamber 169 is decreased. At this time, the hydraulic fluid in the large-diameter pressurizing chamber 169 tends to flow toward the reservoir 12 through the primary supply path 63 having the orifice 139 while pushing up the valve body 175 of the valve mechanism 133. Since the flow rate of the hydraulic fluid flowing through 139 is large, as shown in FIG. 7B, the valve body 175 comes into contact with the valve seat 176 and the on-off valve 177 closes the orifice 174. The hydraulic fluid cannot flow to the reservoir 12 side, and the hydraulic pressure in the large-diameter pressurizing chamber 169 and the primary pressure chamber 65 increases. As a result, before moving the stroke S12, hydraulic fluid is supplied from the primary pressure chamber 65 to the wheel cylinders Ba and Bb, and the secondary piston 24 moves the stroke S11 due to the pressure increase in the primary pressure chamber 65. The port 89 is closed by the cup seal 50, and hydraulic fluid is supplied from the secondary pressure chamber 55 to the wheel cylinders Bc and Bd via the secondary discharge passage 39. The invalid stroke at this time is shorter than S11 + S12 + S13. As described above, the master cylinder 11 is a non-invalid stroke type that closes the port 102 of the primary piston 23 and the port 89 of the secondary piston 24 with different invalid strokes.

  When the hydraulic pressure in the large-diameter pressurizing chamber 169 and the primary pressure chamber 65 becomes lower than the hydraulic pressure on the reservoir 12 side, which is atmospheric pressure, the working fluid is supplied from the reservoir 12 side to the large-diameter pressurizing chamber 169 and the primary pressure chamber 65. At this time, as shown in FIG. 7C, the valve body 175 contacts the valve seat 178 and closes the orifice 139, but the valve plate 135 is elastically deformed and the passage hole is formed. 138 is opened, and liquid supply from the reservoir 12 is performed.

  According to the master cylinder 11 of the fifth embodiment described above, the primary replenishment path 63 that is a communication path that communicates between the reservoir 12 and the primary pressure chamber 65 via the large-diameter pressurizing chamber 169 is provided in the flow path. An orifice 139 having a reduced area and an opening / closing valve 177 for communicating and blocking the primary supply path 63 according to the flow rate of the working fluid passing through the orifice 139 are provided. For this reason, since the flow rate of the hydraulic fluid flowing through the orifice 139 is slow at the time of slow braking and normal braking, the on-off valve 177 is opened and the hydraulic fluid in the primary pressure chamber 65 and the large-diameter pressurizing chamber 169 is discharged from the primary supply path 63 The reservoir 12 can be relieved, and the stroke until the primary piston 23 closes the port 102 with the cup seal 60 can be made invalid. On the other hand, since the flow rate of the working fluid flowing through the orifice 139 is high at the time of sudden braking, the on-off valve 177 is closed so that the working fluid in the primary pressure chamber 65 and the large-diameter pressurizing chamber 169 cannot be released to the reservoir 12. The invalid stroke can be terminated before 23 closes port 102 with cup seal 60. Therefore, at the time of slow braking and normal braking, the invalid stroke can be lengthened to contribute to the improvement of the regeneration efficiency. In addition, at the time of sudden braking, the invalid stroke can be shortened to prevent the lengthening thereof.

“Sixth Embodiment”
Next, a master cylinder according to the sixth embodiment will be described mainly on the difference from the fifth embodiment with reference to FIG. In addition, about the site | part which is common in 5th Embodiment, it represents with the same name and the same code | symbol.

  In the sixth embodiment, the primary piston 23 does not have a stepped shape on the outer diameter side of the cylindrical portion 99 unlike the fifth embodiment. In accordance with this, the cylinder body 16 is also not formed with the large-diameter sliding inner diameter portion 165 of the fifth embodiment. The sliding inner diameter portion 21 is formed with a seal groove 44 that holds the cup seal 60, an opening groove 72, and a seal groove 47 that holds the partition seal 83. In addition, the liquid passage 71 of the fifth embodiment that connects the opening groove 72 to the reservoir 12 side rather than the valve mechanism 133 is not formed, and the communication hole 61 of the primary replenishment path 63 opens into the opening groove 72. The primary piston 23 is slidably supported by the sliding inner diameter portion 21, the cup seal 60 and the partition seal 83.

  Next, the operation of the master cylinder 11 of the sixth embodiment will be described.

  From the non-braking state shown in FIG. 8, there is an operation input to the brake pedal PB, and the booster 201 presses the primary piston 23 toward the bottom 13 of the cylinder body 16 by this input. At this time, the primary piston 23 moves the stroke S12 toward the bottom portion 13 as in the fifth embodiment at the time of slow braking when the operation input of the brake pedal PB is slow operation and at the time of normal braking which is normal operation. Although the volume of the primary pressure chamber 65 is reduced, the hydraulic fluid in the primary pressure chamber 65 flows to the reservoir 12 via the port 102 and the primary supply path 63. At this time, the hydraulic fluid flowing through the orifice 139 of the primary replenishment path 63 has a slow flow rate, and therefore smoothly flows to the reservoir 12 side while slightly pushing up the valve body 175, so that the hydraulic pressure in the primary pressure chamber 65 does not increase, so The piston 24 does not move either.

  When the primary piston 23 moves a stroke S12 until the port 102 is closed by the cup seal 60, the port 102 that has communicated the primary pressure chamber 65 to the primary supply path 63 is closed by the cup seal 60. As the primary piston 23 further moves toward the bottom 13, hydraulic fluid is supplied from the primary pressure chamber 65 to the wheel cylinders Ba and Bb via the primary discharge path 40. At this time, due to the pressure increase in the primary pressure chamber 65, the secondary piston 24 moves in the stroke S11, the port 89 is closed by the cup seal 50, and further moved to the bottom 13 side. The hydraulic fluid is supplied to the wheel cylinders Bc and Bd via the secondary discharge passage 39. The invalid stroke at this time is S11 + S12.

  On the other hand, at the time of sudden braking in which the operation input of the brake pedal PB is sudden operation, the primary piston 23 moves to the bottom 13 side while pushing and contracting the primary piston spring 105 at a faster speed than that at the time of normal braking. Then, the hydraulic fluid in the primary pressure chamber 65 tends to flow to the reservoir 12 via the port 102 and the primary replenishment path 63. However, since the flow velocity flowing through the orifice 139 is fast, the valve body 175 has the same flow rate as in the fifth embodiment. The communication between the valve chamber 171 and the orifice 174 is cut off, and the fluid pressure in the primary pressure chamber 65 increases without flowing into the reservoir 12. As a result, before moving the stroke S12, the hydraulic fluid is supplied from the primary pressure chamber 65 to the wheel cylinders Ba and Bb, and the secondary piston 24 moves through the stroke S11 due to the pressure increase in the primary pressure chamber 65, so that the port 89 Is closed by the cup seal 50, and then hydraulic fluid is supplied from the secondary pressure chamber 55 to the wheel cylinders Bc and Bd via the secondary discharge passage 39. The invalid stroke at this time is shorter than S11 + S12 and is substantially about S11. This master cylinder 11 is also an invalid stroke non-closed type.

  As described above, according to the sixth embodiment, it is possible to increase the invalid stroke during slow braking and normal braking to contribute to the improvement of the regeneration efficiency. In addition, during sudden braking, the invalid stroke is shortened to prevent the lengthening of the stroke. It will be possible.

" Reference technology "
Next, the master cylinder according to the reference technique will be described mainly on the difference from the sixth embodiment based on FIG. In addition, about the site | part which is common in 6th Embodiment, it represents with the same name and the same code | symbol.

In the reference technique , the valve mechanism 133 is not provided. Further, in the sliding inner diameter portion 21 of the cylinder body 16, a seal groove 181 is formed between the seal groove 44 that holds the cup seal 60 and the opening groove 72, and the cup seal 182 is held in the seal groove 181. . The cup seal 182 also has an E shape on one side of the radial cross section including its center line. The cup seal 182 allows the primary replenishment path 63 and the primary pressure chamber 65 to communicate with each other via the port 102 when the primary piston 23 positions the port 102 closer to the opening 15 than the cup seal 182. In a state where 102 is positioned closer to the bottom 13 than the cup seal 182, the space between the primary supply path 63 and the primary pressure chamber 65 can be sealed.

  Thereby, the primary replenishment path (first communication path) 63 is provided in the inner peripheral surface of the cylinder body 16 so as to open, and when the primary piston 23 is in the non-braking position, the reservoir 12 and the primary pressure chamber 65 Communicate between the two. In addition, a pair of cup seals (seal members) 60 and 182 on which the outer peripheral surface of the primary piston 23 slides are arranged in the axial direction of the cylinder body 16 on the bottom 13 side of the cylinder body 16 with respect to the primary supply path 63. Has been.

  A communication path 184 that opens to the inner peripheral surface of the cylinder body 16 is formed between the pair of cup seals 60 and 182 at the bottom of the mounting hole 37 of the cylinder body 16. The communication passage 184 has a large-diameter passage hole 185 on the attachment hole 37 side, and an orifice 186 having a smaller diameter than the passage hole 185 on the opposite side to the attachment hole 37. The communication passage 184 allows the reservoir 12 and the primary pressure chamber 65 to communicate with each other via the port 108 when the port 108 of the primary piston 23 is positioned between the cup seals 60 and 182. Even if the port 108 of the primary piston 23 overlaps with the cup seal 182, if the hydraulic pressure in the primary pressure chamber 65 is higher than the hydraulic pressure in the reservoir 12, the cup seal 182 opens and the port 10 and the seal groove 181 are opened. Further, the reservoir 12 and the primary pressure chamber 65 communicate with each other via the communication path 184.

Next, the operation of the master cylinder 11 of the reference technique will be described.

  From the non-braking state shown in FIG. 9, there is an operation input to the brake pedal PB, and this input causes the booster 201 to press the primary piston 23 toward the bottom 13 of the cylinder body 16. At this time, the primary piston 23 strokes toward the bottom 13 side while contracting the primary piston spring 105 of the distance adjusting unit 106 at the time of slow braking when the operation input of the brake pedal PB is a slow operation and at the time of normal braking which is a normal operation. The volume of the primary pressure chamber 65 is reduced while moving S21 and overlapping the port 108 with the cup seal 182. At this time, the hydraulic fluid in the primary pressure chamber 65 is introduced into the communication path 184 by opening the cup seal 182, and then introduced into the communication path 184 from between the cup seals 60 and 182. At this time, since the flow rate of the hydraulic fluid flowing through the orifice 186 is small, the hydraulic fluid smoothly flows to the reservoir 12 side via the communication path 184, and the hydraulic pressure in the primary pressure chamber 65 does not increase. Do not move. Then, the primary piston 23 moves while compressing the primary piston spring 105 through the stroke S22 until the port 102 is closed by the cup seal 60.

  When the primary piston 23 moves in the stroke S22, the port 102 of the primary piston 23 that has communicated the primary pressure chamber 65 with the communication passage 184 is closed by the cup seal 60, and the primary piston 23 further moves toward the bottom 13 side. Thus, the hydraulic fluid is supplied from the primary pressure chamber 65 to the wheel cylinders Ba and Bb through the primary discharge passage 40. Further, due to the pressure increase in the primary pressure chamber 65 at this time, the secondary piston 24 that has previously connected the secondary pressure chamber 55 to the reservoir 12 by the port 89 is contracting the secondary piston spring 92 of the interval adjusting unit 93. The stroke S21 is moved. Then, the port 89 of the secondary piston 24 is closed by the cup seal 50, and the secondary piston 24 further moves to the bottom 13 side, so that the hydraulic fluid is transferred from the secondary pressure chamber 55 to the wheel cylinders Bc and Bd via the secondary discharge passage 39. Supply. The invalid stroke at this time is S21 + S22.

  On the other hand, at the time of sudden braking in which the operation input of the brake pedal PB is sudden operation, the primary piston 23 moves to the bottom 13 side while pushing and contracting the primary piston spring 105 at a faster speed than that at the time of normal braking. Then, the hydraulic fluid in the primary pressure chamber 65 opens the cup seal 182 as described above, or is directly introduced into the communication path 184 from between the cup seals 60 and 182, but the hydraulic fluid flowing through the orifice 186. Therefore, the flow rate is reduced by the orifice 186, the hydraulic fluid cannot flow from the communication path 184 to the reservoir 12, and the hydraulic pressure in the primary pressure chamber 65 increases. As a result, before moving the stroke S22, the hydraulic fluid is supplied from the primary pressure chamber 65 to the wheel cylinders Ba and Bb, and the secondary piston 24 moves through the stroke S21 due to the pressure increase in the primary pressure chamber 65, so that the port 89 Is closed by the cup seal 50, and the secondary piston 24 further moves toward the bottom 13, whereby hydraulic fluid is supplied from the secondary pressure chamber 55 to the wheel cylinders Bc and Bd via the secondary discharge passage 39. The invalid stroke at this time is shorter than S21 + S22. This master cylinder 11 is also an invalid stroke non-closed type.

As described above, according to the reference technique , it is possible to lengthen the invalid stroke at the time of slow braking and normal braking to contribute to the improvement of the regeneration efficiency. In addition, at the time of sudden braking, the invalid stroke can be shortened to prevent the lengthening thereof.

11 Master cylinder 12 Reservoir 16 Cylinder body 23 Primary piston (hydraulic piston)
25 Reaction piston 60 Cup seal (seal member)
63 Primary supply path (communication path, first communication path)
65 Primary pressure chamber (pressure chamber)
70 Cup seal (seal member)
79 Orifice 80 Reaction force liquid chamber 81 Communication path 118 Reaction force spring 139 Orifice 141 Communication path 144 Orifice 177 On-off valve 182 Cup seal 184 Communication path (second communication path)
186 Orifice

Claims (3)

A bottomed cylindrical cylinder body into which hydraulic fluid is introduced from the reservoir;
A hydraulic piston slidably fitted into the cylinder body and defining a pressure chamber in the cylinder body;
A reaction force piston that is provided closer to the opening side of the cylinder body than the hydraulic piston and presses the hydraulic piston when a predetermined amount is moved by a brake pedal operation input from a non-braking position;
A reaction force liquid chamber formed between the reaction force piston and the hydraulic piston and provided with a reaction force spring;
A communication path communicating between the reaction force liquid chamber and the reservoir;
A seal member that shuts off communication between the communication path and the reaction force liquid chamber as the reaction force piston moves with respect to the cylinder body, and confines the working fluid in the reaction force liquid chamber;
In the communication path, the hydraulic fluid in the reaction force liquid chamber moves to the reservoir until the seal member is changed from a communication state to a blocking state between the communication path and the reaction force liquid chamber. With an orifice in the middle ,
The orifice smoothly flows hydraulic fluid from the reaction force fluid chamber to the reservoir so that the reaction force piston contacts the hydraulic piston when the operation input of the brake pedal is a slow operation, When the brake pedal operation input is a sudden operation at a speed faster than the slow operation, the flow of hydraulic fluid from the reaction force fluid chamber to the reservoir is inhibited so that the fluid pressure in the reaction force fluid chamber increases. A master cylinder characterized by its size . A bottomed cylindrical cylinder body into which hydraulic fluid is introduced from the reservoir;
A hydraulic piston slidably fitted into the cylinder body and defining a pressure chamber in the cylinder body;
A reaction force piston that is provided closer to the opening of the cylinder body than the pressure chamber and moves in accordance with the operation of a brake pedal and moves a predetermined amount from a non-braking position;
A reaction force liquid chamber formed between the reaction force piston and the hydraulic piston and in which a reaction force spring is disposed;
A master cylinder having a communication path that communicates between the reaction force liquid chamber and the pressure chamber and is provided with an orifice in the middle. A bottomed cylindrical cylinder body into which hydraulic fluid is introduced from the reservoir;
A piston slidably fitted into the cylinder body and defining a pressure chamber in the cylinder body;
A communication path communicating between the reservoir and the pressure chamber;
A seal member that communicates and blocks between the communication path and the pressure chamber as the piston moves relative to the cylinder body;
In the communication path, an orifice having a reduced flow area, an on-off valve provided on the reservoir side of the orifice and communicating and blocking the orifice according to the flow rate of the working fluid passing through the orifice , A reverse flow that blocks the flow of hydraulic fluid from the pressure chamber to the reservoir in a passage communicating between the reservoir and the pressure chamber in parallel with the orifice, and allows the flow of hydraulic fluid from the reservoir to the pressure chamber. A master cylinder, characterized in that a stop valve is provided.

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