JP6749499B2 - Master cylinder - Google Patents

Description

The present invention relates to a master cylinder that supplies hydraulic pressure to a braking cylinder of a vehicle.
The present application claims priority based on Japanese Patent Application No. 2017-164362 filed in Japan on August 29, 2017, and the content thereof is incorporated herein.

2. Description of the Related Art There is known a master cylinder in which a circumferential surface in which a seal member is arranged has an inclined surface that restricts a radial movement of a center lip portion of the seal member (see, for example, Patent Document 1).

Japanese Patent No. 5784228

In a master cylinder having a seal member that blocks the flow of the brake fluid from the pressure chamber to the reservoir and allows the brake fluid to flow in the opposite direction, there is a demand to increase the flow rate when the brake fluid flows.

The present invention provides a master cylinder capable of increasing the flow rate during brake fluid flow.

According to one aspect of the present invention, in the master cylinder, the circumferential groove inclines so as to be located radially inward from the bottom side end of the cylinder body at the groove bottom so as to be located closer to the bottom side. A groove is formed in the cylinder body, the groove having an inclined portion and opening to the inclined portion and extending from the circumferential groove toward the pressure chamber toward the bottom portion.

According to the master cylinder described above, it is possible to increase the flow rate when the brake fluid flows.

It is a sectional view showing a master cylinder concerning an embodiment of the present invention. It is a partial expanded sectional view of a basic state which shows the principal part of the master cylinder which concerns on embodiment of this invention. It is a partial expanded sectional view showing a state at the time of normal braking showing an important section of a master cylinder concerning an embodiment of the present invention. It is a partial expanded sectional view showing the state at the time of pumping up of brake fluid which shows the important section of the master cylinder concerning the embodiment of the present invention.

An embodiment of the present invention will be described with reference to the drawings. In the master cylinder 11 shown in FIG. 1, a force corresponding to an operation amount of a brake pedal (not shown) is introduced through an output shaft of a brake booster (not shown) to generate a brake fluid pressure corresponding to an operation amount of the brake pedal. .. A reservoir 12 (only a part of which is shown in FIG. 1) for supplying and discharging the brake fluid is attached to the master cylinder 11 on the upper side in the vertical direction. Although the reservoir 12 is directly attached to the master cylinder 11 in the present embodiment, the reservoir may be arranged at a position separated from the master cylinder 11 and the reservoir and the master cylinder 11 may be connected by piping. ..

The master cylinder 11 has a cylinder body 15. The cylinder body 15 is formed by processing one material into a bottomed tubular shape having a bottom portion 13 and a tubular portion 14. The cylinder body 15 has an opening 16 on the first side and a bottom 13 on the second side. On the side of the opening 16 in the cylinder body 15, a metal primary piston 18 (piston) is movably arranged so as to partially project from the cylinder body 15. A secondary piston 19 (piston), also made of metal, is movably arranged on the bottom portion 13 side of the primary piston 18 in the cylinder body 15. An inner peripheral hole 21 having a bottom surface is formed in the primary piston 18. An inner peripheral hole 22 having a bottom surface is formed in the secondary piston 19. The master cylinder 11 is a so-called plunger type. The master cylinder 11 is a tandem type master cylinder having the two primary pistons 18 and the secondary pistons 19 as described above. The embodiment of the present invention is not limited to the above-mentioned tandem type master cylinder, but a plunger type master cylinder may be a single type master cylinder having one piston in the cylinder body, or three or more master cylinders. The present invention can be applied to any plunger type master cylinder such as a master cylinder having a piston.

The cylinder main body 15 has a mounting portion 23 projecting to the outside in a radial direction (hereinafter, referred to as a cylinder radial direction) orthogonal to the central axis of the tubular portion 14, that is, a side far from the central axial line of the tubular portion 14. It is integrally formed at a predetermined position in the circumferential direction (hereinafter referred to as the cylinder circumferential direction). The mounting base 23 has mounting holes 24 and 25 for mounting the reservoir 12. In the present embodiment, the mounting hole 24 and the mounting hole 25 are aligned in the cylinder circumferential direction with respect to each other in the direction of the central axis (hereinafter, referred to as the cylinder axis) of the tubular portion 14 of the cylinder body 15. It is formed at a vertically displaced upper position. The cylinder body 15 is arranged in the vehicle such that the cylinder axis direction is along the vehicle front-rear direction.

A secondary discharge passage 26 (discharge passage), which is a discharge passage for the brake fluid, is formed near the bottom portion 13 on the side of the mounting portion 23 of the cylinder portion 14 of the cylinder body 15. Further, a primary discharge passage 27 (discharge passage) that is a discharge passage of the brake fluid is formed on the opening 16 side of the cylinder body 15 with respect to the secondary discharge passage 26. Although not shown, the secondary discharge passage 26 and the primary discharge passage 27 communicate with a braking cylinder such as a disc brake or a drum brake via a brake pipe, and discharge the brake fluid toward the braking cylinder. In addition, in the present embodiment, the secondary discharge passage 26 and the primary discharge passage 27 are formed with the positions in the cylinder axial direction being shifted while the positions in the cylinder circumferential direction are matched with each other.

In the secondary discharge passage 26 and the primary discharge passage 27, the brake fluid pressure to the braking cylinder is controlled by pumping up the brake fluid from the master cylinder 11 and discharging it toward the braking cylinder. An ESC device (not shown) used for automatic emergency braking is provided.

A sliding inner diameter portion 28 is formed on the inner peripheral portion of the cylinder portion 15 of the cylinder body 15 on the side of the bottom portion 13. The sliding inner diameter portion 28 projects inward in the cylinder radial direction and is formed in an annular shape in the cylinder circumferential direction. The secondary piston 19 is slidably fitted on the smallest inner diameter surface 28 a of the sliding inner diameter portion 28. The secondary piston 19 is guided by the minimum inner diameter surface 28a and moves in the cylinder axial direction. A sliding inner diameter portion 29 is formed on the inner peripheral portion of the cylinder portion 15 of the cylinder body 15 on the opening 16 side. The sliding inner diameter portion 29 projects inward in the cylinder radial direction and is formed in an annular shape in the cylinder circumferential direction. The primary piston 18 is slidably fitted to the minimum inner diameter surface 29a of the sliding inner diameter portion 29, and is guided by the minimum inner diameter surface 29a to move in the cylinder axial direction.

In the sliding inner diameter portion 28, a plurality of, specifically two, annular circumferential grooves 30 and 31 are formed in this order from the bottom portion 13 side in this order from the bottom portion 13 side by shifting the position in the cylinder axial direction. .. Further, in the sliding inner diameter portion 29, a plurality of, specifically two, annular grooves 32 and 33 are formed in this order from the bottom portion 13 side in the cylinder axial direction, all of which are annular. ing.
The circumferential grooves 30, 31 have a shape that is annular in the cylinder circumferential direction and is recessed outward of the smallest inner diameter surface 28a in the cylinder radial direction. The circumferential grooves 32 and 33 have a shape that is annular in the cylinder circumferential direction and is recessed outward of the smallest inner diameter surface 29a in the cylinder radial direction. The circumferential grooves 30 to 33 are formed inside the cylinder body 15. All of the circumferential grooves 30 to 33 are formed by cutting.

The peripheral groove 30 closest to the bottom 13 among the peripheral grooves 30 to 33 is formed in the vicinity of the mounting hole 24 and the mounting hole 24 on the bottom 13 side of the mounting holes 25. An annular piston seal 35 (seal member) is arranged in the circumferential groove 30 so as to be held by the circumferential groove 30.

An opening groove 37 is formed on the sliding inner diameter portion 28 of the cylinder body 15 on the opening 16 side with respect to the circumferential groove 30. The opening groove 37 is an annular groove that is recessed outward in the cylinder radial direction from the smallest inner diameter surface 28a. The opening groove 37 opens the communication hole 36, which is formed from the mounting hole 24 on the bottom portion 13 side, into the cylindrical portion 14. Here, the opening groove 37 and the communication hole 36 form a secondary replenishment passage 38 (replenishment passage) that is provided in the cylinder body 15 and is in constant communication with the reservoir 12. In other words, the cylinder body 15 has the secondary supply passage 38 communicating with the reservoir 12.

A communication groove 41 (groove) is formed on the sliding inner diameter portion 28 of the cylinder body 15 closer to the bottom portion 13 than the circumferential groove 30. The communication groove 41 opens to the circumferential groove 30 and extends linearly from the circumferential groove 30 toward the bottom portion 13 in the cylinder axis direction. The communication groove 41 (groove) is formed so as to be recessed outside the minimum inner diameter surface 28a in the cylinder radial direction. The communication groove 41 allows the secondary discharge passage 26 formed at a position between the bottom portion 13 and the peripheral groove 30 and in the vicinity of the bottom portion 13 to communicate with the peripheral groove 30 via a secondary pressure chamber 68 described later. .. The communication groove 41 extends from the circumferential groove 30 toward the bottom portion 13 side to the secondary pressure chamber 68.

In the sliding inner diameter portion 28 of the cylinder body 15, the peripheral groove 31 is formed on the side opposite to the peripheral groove 30 of the opening groove 37 in the cylinder axis direction, that is, on the opening 16 side. An annular partition seal 42 is arranged in the circumferential groove 31 so as to be held by the circumferential groove 31.

In the sliding inner diameter portion 29 of the cylinder body 15, the above-mentioned peripheral groove 32 is formed in the vicinity of the mounting hole 25 on the opening 16 side. An annular piston seal 45 (seal member) is arranged in the circumferential groove 32 so as to be held by the circumferential groove 32.

An opening groove 47 is formed in the sliding inner diameter portion 29 of the cylinder body 15 on the opening 16 side of the circumferential groove 32. The opening groove 47 is an annular groove that is recessed outward in the cylinder radial direction from the smallest inner diameter surface 29a. The opening groove 47 opens the communication hole 46, which is formed from the mounting hole 25 on the opening 16 side, into the cylindrical portion 14. Here, the opening groove 47 and the communication hole 46 mainly form a primary replenishment passage 48 (replenishment passage) provided in the cylinder body 15 and always communicating with the reservoir 12. In other words, the cylinder body 15 has the primary supply passage 48 that communicates with the reservoir 12.

A communication groove 51 (groove) is formed on the sliding inner diameter portion 29 of the cylinder body 15 closer to the bottom portion 13 than the circumferential groove 32. The communication groove 51 opens to the peripheral groove 32 and extends linearly from the peripheral groove 32 toward the bottom portion 13 in the cylinder axial direction. The communication groove 51 (groove) is formed so as to be recessed outside the minimum inner diameter surface 29a in the cylinder radial direction. The communication groove 51 includes a primary discharge passage 27 formed between the peripheral groove 31 and the peripheral groove 32 and in a position near the peripheral groove 31, and the peripheral groove 32 via a primary pressure chamber 85 described later. To communicate. The communication groove 51 extends from the circumferential groove 32 toward the bottom portion 13 side to the primary pressure chamber 85.

A circumferential groove 33 is formed in the sliding inner diameter portion 29 of the cylinder body 15 on the side opposite to the circumferential groove 32 of the opening groove 47, that is, in the opening portion 16. An annular partition seal 52 is arranged in the circumferential groove 33 so as to be held by the circumferential groove 33.

The secondary piston 19 arranged on the bottom portion 13 side of the cylinder body 15 includes a first cylindrical portion 55, a bottom portion 56 formed on one side in the axial direction of the first cylindrical portion 55, and a first cylinder of the bottom portion 56. It has a shape having a second cylindrical portion 57 formed on the opposite side to the shape portion 55. The inner peripheral hole 22 is formed by the first cylindrical portion 55 and the bottom portion 56. The secondary piston 19 has inner circumferences of the piston seal 35 and the partition seal 42 provided in the sliding inner diameter portion 28 of the cylinder body 15 with the first cylindrical portion 55 arranged on the bottom portion 13 side of the cylinder body 15. Is slidably fitted to.

An annular recess 59 is formed on the outer periphery of the end of the first cylindrical portion 55 opposite to the bottom 56. The recess 59 is recessed inward in the radial direction with respect to the outermost surface 19A of the secondary piston 19 and the largest outer diameter surface 19a having the largest diameter. In this recess 59, a plurality of ports 60 penetrating in the cylinder radial direction on the bottom 56 side thereof are formed radially at equal intervals in the cylinder circumferential direction.

A space adjusting portion 63 is provided between the secondary piston 19 and the bottom portion 13 of the cylinder body 15. The interval adjusting unit 63 includes a secondary piston spring 62 that determines these intervals in a non-braking state where there is no input from the output shaft of a brake booster (not shown). The space adjusting portion 63 is connected to a locking member 64 that abuts on the bottom portion 13 of the cylinder body 15, and is connected to the locking member 64 so as to slide only within a predetermined range and abuts on the bottom portion 56 of the secondary piston 19. It has a locking member 65. The secondary piston spring 62 is interposed between the locking member 64 and the locking member 65.

A secondary pressure chamber that is formed by the bottom portion 13 of the cylinder body 15 and the bottom portion 13 side of the cylinder portion 14 and the secondary piston 19 to generate brake fluid pressure and supply the brake fluid pressure to the secondary discharge passage 26. 68 (pressure chamber) is formed. In other words, the secondary piston 19 forms a secondary pressure chamber 68 that supplies hydraulic pressure to the secondary discharge passage 26, between the secondary piston 19 and the cylinder body 15. The secondary pressure chamber 68 communicates with the secondary supply passage 38, that is, the reservoir 12 when the secondary piston 19 is at a position where the port 60 opens the secondary supply passage 38.

The partition seal 42 held in the circumferential groove 31 of the cylinder body 15 is an integrally molded product made of synthetic rubber. The partition seal 42 has a C-shaped radial cross-section including the center line. The partition seal 42 has an inner periphery slidingly contacting the outer peripheral surface 19A of the secondary piston 19 that moves in the cylinder axial direction, and an outer periphery contacting the peripheral groove 31 of the cylinder body 15. Thereby, the partition seal 42 constantly seals the gap between the secondary piston 19 and the partition seal 42 of the cylinder body 15.

The piston seal 35 held in the circumferential groove 30 of the cylinder body 15 is an integrally molded product made of synthetic rubber such as EPDM. The piston seal 35 has an E-shaped one side in a radial cross section including the center line thereof. The inner circumference of the piston seal 35 is in sliding contact with the outer circumferential surface 19A of the secondary piston 19 that moves in the cylinder axis direction. The outer circumference of the piston seal 35 contacts the circumferential groove 30 of the cylinder body 15. The piston seal 35 provided in the circumferential groove 30 can seal between the secondary supply passage 38 and the secondary pressure chamber 68 when the secondary piston 19 positions the port 60 on the bottom 13 side of the piston seal 35. It is configured. That is, the piston seal 35 can block and seal the communication between the secondary pressure chamber 68 and the secondary supply passage 38 and the reservoir 12. In this sealed state, the secondary piston 19 slides on the sliding inner diameter portion 28 of the cylinder body 15 and the inner circumference of the piston seal 35 and the partition seal 42 held by the cylinder body 15 to move to the bottom portion 13 side. The brake fluid in the secondary pressure chamber 68 is pressurized. The brake fluid pressurized in the secondary pressure chamber 68 is supplied from the secondary discharge passage 26 to the wheel-side braking cylinder.

When there is no input from the output shaft of the brake booster (not shown) and the secondary piston 19 is in the basic position (non-braking position) for opening the port 60 to the secondary supply passage 38 as shown in FIG. Is in the recess 59 of the secondary piston 19 and a part thereof overlaps the port 60 in the cylinder axial direction. Then, when the secondary piston 19 moves toward the bottom portion 13 side of the cylinder body 15 and the inner peripheral portion of the piston seal 35 entirely overlaps the port 60, the communication between the secondary pressure chamber 68 and the reservoir 12 is cut off.

The primary piston 18 arranged on the opening 16 side of the cylinder body 15 includes a first cylindrical portion 71, a bottom portion 72 formed on one side of the first cylindrical portion 71 in the axial direction, and a first portion of the bottom portion 72. It has a shape having a cylindrical portion 71 and a second cylindrical portion 73 formed on the opposite side. The inner peripheral hole 21 is formed by a first cylindrical portion 71 and a bottom portion 72. The primary piston 18 has the first cylindrical portion 71 disposed on the side of the secondary piston 19 in the cylinder body 15, and has the piston seal 45 and the partition seal 52 provided on the sliding inner diameter portion 29 of the cylinder body 15, respectively. It is slidably fitted to the inner circumference. An output shaft of a brake booster (not shown) is inserted inside the second cylindrical portion 73. The bottom 72 is pressed by this output shaft.

An annular recess 75 is formed on the outer periphery of the end of the first cylindrical portion 71 opposite to the bottom 72. The recessed portion 75 is recessed inward in the radial direction from the largest outer diameter surface 18a having the largest diameter on the outer peripheral surface 18A of the primary piston 18. In the recess 75, a plurality of ports 76 penetrating in the radial direction on the bottom portion 72 side are radially formed at equally spaced positions in the cylinder circumferential direction.

A space adjusting unit 79 is provided between the secondary piston 19 and the primary piston 18. The interval adjusting unit 79 includes a primary piston spring 78 that determines these intervals in a non-braking state where there is no input from the output shaft of a brake booster (not shown). The gap adjusting portion 79 has a locking member 81 that abuts on the bottom portion 72 of the primary piston 18, a locking member 82 that abuts on the bottom portion 56 of the secondary piston 19, and one end portion of the locking member 81 that is fixed and engaged. It has a shaft member 83 which slidably supports the stopper member 82 only within a predetermined range. The primary piston spring 78 is interposed between the locking member 81 and the locking member 82.

Here, a portion formed by being surrounded by the cylinder portion 14, the primary piston 18, and the secondary piston 19 of the cylinder body 15 generates a brake fluid pressure and supplies the brake fluid to the primary discharge passage 27. (Pressure chamber). In other words, the primary piston 18 forms, between the secondary piston 19 and the cylinder body 15, a primary pressure chamber 85 that supplies hydraulic pressure to the primary discharge passage 27. The primary pressure chamber 85 communicates with the primary replenishment passage 48, that is, the reservoir 12 when the primary piston 18 is at the position where the port 76 opens the primary replenishment passage 48.

The partition seal 52 held in the circumferential groove 33 of the cylinder body 15 is a component common to the partition seal 42. The partition seal 52 is an integrally molded product made of synthetic rubber. The partition seal 52 has a C-shaped one side shape in a radial cross section including the center line thereof. The partition seal 52 has an inner periphery slidingly contacting the outer peripheral surface 18A of the primary piston 18 that moves in the cylinder axial direction, and an outer periphery contacting the peripheral groove 33 of the cylinder body 15. As a result, the partition seal 52 constantly seals the gap between the primary piston 18 and the partition seal 52 of the cylinder body 15.

The piston seal 45 held in the circumferential groove 32 of the cylinder body 15 is a common component with the piston seal 35. The piston seal 45 is an integrally molded product made of synthetic rubber such as EPDM. The piston seal 45 has an E-shape on one side in a radial cross section including the center line thereof. The inner periphery of the piston seal 45 is in sliding contact with the outer peripheral surface 18A of the primary piston 18 that moves in the cylinder axis direction. The outer circumference of the piston seal 45 contacts the circumferential groove 32 of the cylinder body 15. The piston seal 45 provided in the circumferential groove 32 can seal between the primary supply passage 48 and the primary pressure chamber 85 when the primary piston 18 positions the port 76 on the bottom 13 side of the piston seal 45. Has become. That is, the piston seal 45 can block and seal the communication between the primary pressure chamber 85 and the primary supply passage 48 and the reservoir 12. In this sealed state, the primary piston 18 slides on the sliding inner diameter portion 29 of the cylinder body 15 and the inner circumference of the piston seal 45 and the partition seal 52 held by the cylinder body 15 to move to the bottom portion 13 side. The brake fluid in the primary pressure chamber 85 is pressurized. The brake fluid pressurized in the primary pressure chamber 85 is supplied from the primary discharge passage 27 to the wheel-side braking cylinder.

When there is no input from the output shaft of the brake booster (not shown) and the primary piston 18 is at the basic position (non-braking position) for opening the port 76 to the primary supply passage 48 as shown in FIG. Inside the recess 75 of the primary piston 18, a part of the port 76 overlaps with the cylinder axial direction. Then, when the primary piston 18 moves toward the bottom portion 13 side of the cylinder body 15 and the inner peripheral portion of the piston seal 45 entirely overlaps the port 76, the communication between the primary pressure chamber 85 and the reservoir 12 is cut off.

Here, the peripheral groove 30, the communicating groove 41 of the cylinder body 15, the vicinity thereof, the piston seal 35, and the first cylinder including the recess 59 of the secondary piston 19 and the port 60, which are the sliding contact portions of the piston seal 35. The structural portion including the tip portion of the shape portion 55 is referred to as a secondary-side seal structural portion SS that switches communication and cutoff between the secondary supply passage 38 and the secondary pressure chamber 68. Further, the peripheral groove 32 of the cylinder body 15, the communication groove 51 and the vicinity thereof, the piston seal 45, and the first cylindrical shape including the recess 75 and the port 76 of the primary piston 18, which is the sliding contact portion of the piston seal 45. A structural portion including the tip portion of the portion 71 is referred to as a primary-side seal structural portion SP that switches communication and cutoff between the primary supply passage 48 and the primary pressure chamber 85.

The piston seal 35 and the piston seal 45 are common parts having the same shape. The circumferential groove 30 and the communication groove 41 have the same shape as the circumferential groove 32 and the communication groove 51. The recess 59 and the port 60 have the same shape as the recess 75 and the port 76, and the secondary side seal structure portion SS and the primary side seal structure portion SP have the same structure. Therefore, in the following, these details will be described by taking the seal structure portion SP on the primary side as an example, mainly with reference to FIGS. 2 to 4. The opening 16 side of the cylinder body 15 in the cylinder axis direction is referred to as the cylinder opening side. The bottom 13 side of the cylinder body 15 in the cylinder axis direction is referred to as the cylinder bottom side.

As shown in FIG. 2, the circumferential groove 32 has a groove bottom 88 on the inner side in the recess direction, that is, on the outer side in the cylinder radial direction. Further, the circumferential groove 32 has a circumferential wall 89. The peripheral wall 89 extends inward in the cylinder radial direction from the edge of the groove bottom 88 on the cylinder opening side. Further, the circumferential groove 32 has a circumferential wall 90. The peripheral wall 90 extends inward in the cylinder radial direction from the end of the groove bottom 88 on the cylinder bottom side. The groove bottom 88, the peripheral wall 89 and the peripheral wall 90 are formed on the cylinder body 15 itself. The groove bottom 88, the peripheral wall 89, and the peripheral wall 90 are formed by cutting the cylinder body 15.

The groove bottom 88 has a groove bottom surface portion 88a. The groove bottom surface portion 88a is a cylindrical surface having the cylinder axis as a center, and the length in the cylinder axis direction is constant over the entire circumference in the cylinder circumferential direction.

The peripheral wall 89 on the cylinder opening side of the peripheral groove 32 has a wall surface portion 89a formed of a flat surface parallel to the surface orthogonal to the cylinder axis. The wall surface portion 89a extends inward in the cylinder radial direction from the edge portion of the groove bottom surface portion 88a on the cylinder opening side. The wall surface portion 89a has a constant inner diameter, a constant outer diameter, and a constant width in the cylinder radial direction over the entire circumference in the cylinder circumferential direction. The wall surface portion 89a has an annular shape centered on the cylinder axis.

The peripheral wall 90 on the cylinder bottom side of the peripheral groove 32 is opposed to the peripheral wall 89 in the cylinder axial direction by overlapping the position in the cylinder radial direction. The peripheral wall 90 has an inclined portion 91 on the outer side in the cylinder radial direction, that is, an outer side in the radial direction of the peripheral groove 32, and an inner side in the cylinder radial direction, that is, an axial orthogonal portion 92 on the inner side in the radial direction of the peripheral groove 32. There is.

The inclined portion 91 has an inclined wall surface portion 91a. The inclined wall surface portion 91a is inclined from the end of the groove bottom surface portion 88a on the cylinder bottom side toward the inner side in the radial direction of the circumferential groove 32 so that the inner side in the radial direction is located on the cylinder bottom side in the cylinder axial direction. And extend. The inclined wall surface portion 91a is a tapered surface. In other words, the inclined wall surface portion 91 a is a surface formed from the end of the groove bottom 88 of the circumferential groove 32 on the cylinder bottom side toward the inner side in the radial direction of the circumferential groove 32, and the radial direction of the circumferential groove 32. The inner side of the cylinder is inclined toward the bottom of the cylinder. Therefore, the inclined portion 91 is inclined from the end of the groove bottom 88 on the cylinder bottom side toward the inner side in the radial direction of the peripheral groove 32 so that the inner side in the radial direction of the peripheral groove 32 is located on the cylinder bottom side. Is extended. In other words, the groove bottom 88 has a shape in which the axial end on one side is filled with the inclined wall surface portion 91a having a tapered surface, that is, the inclined portion 91.

The axis orthogonal portion 92 has an axis orthogonal wall surface portion 92a and an R chamfered surface 92b. The axis-orthogonal wall surface portion 92a extends from the inner edge portion of the inclined wall surface portion 91a in the radial direction of the circumferential groove 32 to a flat surface that extends inward in the radial direction of the circumferential groove 32 in parallel with a surface orthogonal to the cylinder axis. It is configured. The R chamfered surface 92b is a curved surface that connects the inner edge of the axially orthogonal wall surface portion 92a in the radial direction of the circumferential groove 32 and the minimum inner diameter surface 29a of the sliding inner diameter portion 29 on the cylinder bottom side of the circumferential groove 32. It consists of

Here, the above-described communication groove 51 includes the inclined wall surface portion 91a of the inclined portion 91, the axis orthogonal wall surface portion 92a and the R chamfered surface 92b of the axis orthogonal portion 92, and the sliding inner diameter on the cylinder bottom side of the circumferential groove 32. The opening is continuous with the smallest inner diameter surface 29a of the portion 29. Therefore, the cylinder body 15 is formed with a communication groove 51 that opens to the inclined portion 91 and extends from the circumferential groove 32 toward the cylinder bottom side. The communication groove 51 is opened only in a part of the inclined wall surface portion 91 a of the inclined portion 91 inside from the intermediate position in the radial direction of the circumferential groove 32. In other words, in the cylinder radial direction, the position of the deepest deepest portion 51a of the communication groove 51 coincides with the middle portion of the inclined wall surface portion 91a.

The inclined wall surface portion 91a has a constant inner diameter, a constant outer diameter, and a constant width in the cylinder radial direction over the entire circumference in the cylinder circumferential direction, except for the opening portion of the communication groove 51. The inclined wall surface portion 91a has an annular shape centered on the cylinder axis. The axis-perpendicular wall surface portion 92a also has a constant inner diameter and a constant outer diameter and a constant width in the cylinder radial direction over the entire circumference in the cylinder circumferential direction except for the opening portion of the communication groove 51, and is centered on the cylinder axis. It has an annular shape.

The recess 75 formed in the first cylindrical portion 71 of the primary piston 18 has a cylindrical surface 75a, a tapered surface 75b, and a tapered surface 75c. The cylindrical surface 75a has a smaller diameter than the cylindrical-shaped maximum outer diameter surface 18a having the largest diameter in the primary piston 18, and has a constant width in the axial direction over the entire circumference. The tapered surface 75b extends so as to be inclined from the end of the cylindrical surface 75a on the cylinder opening side so as to have a larger diameter on the cylinder opening side, and is connected to a portion of the maximum outer diameter surface 18a on the cylinder opening side of the recess 75. ing. The port 76 that is in constant communication with the primary pressure chamber 85 is formed on the cylinder opening side in the tapered surface 75b, and the end portion on the cylinder opening side coincides with the end portion on the cylinder opening side of the tapered surface 75b. The tapered surface 75b has a constant width in the axial direction except for the portion where the port 76 is formed. The tapered surface 75c extends from the end of the cylindrical surface 75a on the cylinder bottom side so as to have a larger diameter toward the cylinder bottom side, and is connected to a portion of the maximum outer diameter surface 18a on the cylinder bottom side of the recess 75. ing. The tapered surface 75c has a constant width in the axial direction over the entire circumference.

The cylindrical surface 75a, the tapered surface 75b, and the tapered surface 75c are formed around the central axis of the primary piston 18, like the maximum outer diameter surface 18a. The tapered surface 75b has a longer axial length than the tapered surface 75c. Therefore, the tapered surface 75b has a smaller taper than the tapered surface 75c.

The piston seal 45 arranged in the circumferential groove 32 has a base portion 101, an inner peripheral lip portion 102, an outer peripheral lip portion 103, and an intermediate lip portion 104. The base portion 101 is arranged on the cylinder opening side of the piston seal 45. The base portion 101 has an annular plate shape parallel to the plane orthogonal to the axis of the piston seal 45. The inner peripheral lip portion 102 has an annular tubular shape extending from the inner peripheral end edge portion of the base portion 101 toward the cylinder bottom side along the cylinder axial direction. The outer peripheral lip portion 103 has an annular tubular shape extending from the outer peripheral edge of the base portion 101 along the cylinder axial direction toward the cylinder bottom side. The intermediate lip portion 104 is between the outer peripheral lip portion 103 and the inner peripheral lip portion 102, and has an annular tubular shape that projects from the base portion 101 toward the cylinder bottom side along the cylinder axial direction. The intermediate lip portion 104, the inner peripheral lip portion 102, and the outer peripheral lip portion 103 have substantially the same amount of protrusion from the base portion 101 in the cylinder axis direction.

The inner peripheral lip portion 102 of the piston seal 45 is in sliding contact with the outer peripheral surface 18A of the primary piston 18 that moves in the cylinder axial direction, including the cylindrical surface 75a, the tapered surface 75b, the tapered surface 75c, and the maximum outer diameter surface 18a. The outer peripheral lip portion 103 of the piston seal 45 contacts the groove bottom surface portion 88 a of the groove bottom 88 of the peripheral groove 32 of the cylinder body 15. In other words, the piston seal 45 includes an inner peripheral lip portion 102 that is in sliding contact with the outer peripheral surface 18A of the primary piston 18, an outer peripheral lip portion 103 that is in contact with the peripheral groove 32 of the cylinder body 15, and an intermediate lip portion 104 therebetween. , And an annular base portion 101 provided so as to project. The end surface 101 a of the base portion 101 on the cylinder opening side of the piston seal 45 can contact the wall surface portion 89 a of the peripheral wall 89.

FIG. 2 shows a basic state (non-braking state before the brake pedal is operated) of the master cylinder 11 in which there is no input from the output shaft side of a brake booster (not shown). In this basic state, the inner peripheral lip portion 102 of the piston seal 45 is in close contact with the cylindrical surface 75a and the tapered surface 75b of the concave portion 75 of the primary piston 18, and the outer peripheral lip portion 103 is the groove bottom of the peripheral groove 32. It is in contact with the groove bottom surface portion 88a of 88. Further, in this basic state, in the piston seal 45, the end surface 101a of the base portion 101 is in contact with the wall surface portion 89a of the peripheral wall 89.

When the master cylinder 11 is in the basic state, the primary piston 18 is located at the basic position (non-braking position) shown in FIG. When the primary piston 18 is in this basic position, the port 76 communicates with the primary supply passage 48. When the primary piston 18 is at the basic position, the piston seal 45 has the inner peripheral lip portion 102 at the position of the cylindrical surface 75a of the recess 75 of the primary piston 18, and the base portion 101 at the position of the tapered surface 75b. The inner peripheral portion of the base portion 101 overlaps the position of the port 76 in the cylinder axial direction with a part of the port 76 on the cylinder bottom side.

When the master cylinder 11 is in the basic state, the piston seal 45 is arranged such that the outer peripheral lip portion 103 overlaps the inclined wall surface portion 91a of the inclined portion 91 of the peripheral groove 32 at a position in the cylinder radial direction so as to face and abut in the cylinder axial direction. ing. In other words, the piston seal 45 is arranged at a position where the tip of the outer peripheral lip portion 103 contacts the inclined portion 91 when the piston seal 45 moves to the cylinder bottom side. Further, in this basic state, the outer peripheral lip portion 103 opposes in the cylinder axial direction by superimposing the position of the deepest portion 51a of the communication groove 51 and the position in the cylinder radial direction. Further, in this basic state, the intermediate lip portion 104 is spaced from the axially orthogonal wall surface portion 92a of the axially orthogonal portion 92 so as to face each other in the cylinder axial direction and overlap with each other in the cylinder radial direction. The axially orthogonal wall surface portion 92a and the R chamfered surface 92b of the axially orthogonal portion 92 are overlapped with the positions in the cylinder radial direction so as to face each other in the cylinder axial direction and are spaced apart from each other.

Then, at the time of normal braking, when there is an input from the output shaft side of a brake booster (not shown) and the primary piston 18 moves from the basic position to the cylinder bottom side, the piston seal 45, together with the primary piston 18, has a circumferential wall inside the circumferential groove 32. Move to 90 side. As a result, the piston seal 45 comes into contact with the axially orthogonal wall surface portion 92a of the peripheral wall 90 at the tip portion of the inner peripheral lip portion 102 and the tip portion of the intermediate lip portion 104, and the movement toward the cylinder bottom side is restricted. When the piston seal 45 moves to the side of the peripheral wall 90 in the peripheral groove 32, the outer peripheral lip portion 103 has its tip end that abuts the inclined wall surface portion 91a of the inclined portion 91, and the peripheral wall portion 91a is inclined by the inclination of the inclined wall surface portion 91a. It moves inward in the radial direction of the groove 32. Further, the end surface 101 a of the base portion 101 is separated from the wall surface portion 89 a of the peripheral wall 89.

When the primary piston 18 further moves to the cylinder bottom side, the piston seal 45, which comes into contact with the axially orthogonal wall surface portion 92a of the peripheral wall 90 and is restricted from moving to the cylinder bottom side, is provided with respect to the moving primary piston 18. By sliding on the outer peripheral surface 18A, the base portion 101 and the inner peripheral lip portion 102 move the tapered surface 75b of the concave portion 75 to the cylinder opening side.

When the primary piston 18 moves further to the cylinder bottom side, the piston seal 45 slidingly contacting the outer peripheral surface 18A of the primary piston 18 crosses over the port 76 and closes the port 76, so that the primary pressure chamber 85 and the primary supply passage 48 are separated from each other. After the communication through the port 76 is cut off, the entire body is mounted on the cylinder opening side portion of the maximum outer diameter surface 18a of the primary piston 18.

As described above, in the range where the primary piston 18 is located on the cylinder bottom side from the position where the piston seal 45 blocks the communication between the primary pressure chamber 85 and the primary replenishment passage 48 via the port 76, basically, it is large. The hydraulic pressure in the primary pressure chamber 85 is higher than the hydraulic pressure in the primary supply passage 48, which is the atmospheric pressure. Then, due to this hydraulic pressure difference, the outer peripheral lip portion 103 of the piston seal 45 is pressed against the groove bottom surface portion 88 a of the groove bottom 88 over the entire circumference. As a result, the inner peripheral lip portion 102 that is constantly pressed against the primary piston 18 and the base portion 101 that connects the inner peripheral lip portion 102 and the primary peripheral portion between the primary groove 18 and the peripheral groove 32 between the primary pressure chamber 85 and the primary supply passage 48. Cut off communication via the. This seals the primary pressure chamber 85. As a result, the hydraulic pressure in the primary pressure chamber 85 rises and the brake fluid in the primary pressure chamber 85 is supplied from the primary discharge passage 27 shown in FIG. 1 to the wheel-side braking cylinder.

The piston seal 45 moves to the primary replenishment passage 48 side, that is, the peripheral wall 89 side in the circumferential groove 32 due to the increase in the hydraulic pressure of the primary pressure chamber 85 described above. Then, after the intermediate lip portion 104 and the inner peripheral lip portion 102 are separated from the peripheral wall 90, the base portion 101 contacts the wall surface portion 89a of the peripheral wall 89 at the end surface 101a, as shown in FIG. During this time, the piston seal 45 maintains the state in which the outer peripheral lip portion 103 is pressed against the groove bottom surface portion 88a of the groove bottom 88 over the entire circumference due to the hydraulic pressure difference between the primary pressure chamber 85 and the primary supply passage 48. As a result, the communication between the primary pressure chamber 85 and the primary replenishing passage 48 via the circumferential groove 32 and the primary piston 18 is blocked.

When the brake pedal (not shown) is returned to release the braking from the state where the primary piston 18 has moved to the cylinder bottom side, the primary piston 18 that moves to the cylinder opening side by the urging force of the gap adjusting portion 63 shown in FIG. The primary piston 18 returns to the basic position shown in FIG. 2 by the urging force of the space adjusting portion 79 shown in FIG.

As shown in FIG. 3, when the primary piston 18 positions the port 76 on the cylinder bottom side of the piston seal 45 and the hydraulic pressure is maintained, when the hydraulic pressure in the primary pressure chamber 85 decreases due to pumping up by the ESC device, After the hydraulic pressure in the primary supply passage 48, which is atmospheric pressure, and the hydraulic pressure in the primary pressure chamber 85 become equal, the hydraulic pressure in the primary pressure chamber 85 becomes a negative pressure, which is lower than the hydraulic pressure in the primary supply passage 48, which is atmospheric pressure. Also, the hydraulic pressure in the primary pressure chamber 85 becomes lower.

Then, as shown in FIG. 4, the negative pressure in the primary pressure chamber 85 sucks the piston seal 45 and moves it toward the peripheral wall 90 to separate the base portion 101 from the peripheral wall 89, and the outer periphery of the piston seal 45. The lip portion 103 is separated from the groove bottom 88 of the circumferential groove 32. Moreover, the movement of the piston seal 45 toward the peripheral wall 90 causes the outer peripheral lip portion 103 to contact the inclined wall surface portion 91a of the inclined portion 91 so that the tip end thereof moves in the cylinder radial direction due to the inclination of the inclined wall surface portion 91a. Move inward. Then, the outer peripheral lip portion 103 falls inward in the cylinder radial direction around the base portion 101 side, and the contact position with the peripheral wall 90 is located inside the deepest portion 51 a of the communication groove 51 in the cylinder radial direction. As a result, the communication groove 51 communicates with the portion between the groove bottom 88 of the circumferential groove 32 and the piston seal 45.

As a result, the brake fluid in the primary replenishment passage 48 is, as shown by the broken line arrow X in FIG. 4, a gap between the peripheral wall 89 and the base portion 101, a gap between the groove bottom 88 and the outer peripheral lip portion 103, and the communication groove 51. It is replenished to the primary pressure chamber 85 via the internal passage. This makes it possible to replenish the brake fluid at a large flow rate when the ESC device pumps up.

When the piston seal 45 moves to the side of the peripheral wall 90, the outer peripheral lip portion 103 deforms with the inclined wall surface portion 91a as a base point, so that the posture is stable. Therefore, the gap between the groove bottom 88 and the outer peripheral lip portion 103 and the passage in the communication groove 51 can be communicated with each other in a stable passage area.

Here, in the master cylinder 11, from the static flow rate which is the flow rate of the brake fluid from the primary replenishment passage 48 to the primary pressure chamber 85 when the primary piston 18 opens the port 76 to the primary replenishment passage 48, Since the dynamic flow rate, which is the flow rate of the brake fluid from the primary supply passage 48 to the primary pressure chamber 85 when the primary piston 18 does not open the port 76 to the primary supply passage 48, the port 76 is closed. Low. The master cylinder 11 of this embodiment can improve this dynamic flow rate.

In the master cylinder described in Patent Document 1 described above, the peripheral groove in which the seal member is arranged has an inclined surface that restricts the radial movement of the center lip portion of the seal member. By the way, in a master cylinder having a seal member that blocks the flow of brake fluid from the pressure chamber to the reservoir and allows the brake fluid to flow in the opposite direction, there is a demand to increase the flow rate of the brake fluid during circulation. In the above master cylinder, when the brake fluid flows from the reservoir to the pressure chamber, the outer peripheral lip portion of the seal member separates from the groove bottom of the circumferential groove to allow the brake fluid to flow. However, the seal member sucked to the pressure chamber side moves to the pressure chamber side in the circumferential groove and contacts the circumferential wall on the cylinder bottom side of the circumferential groove. Due to the contact of the sealing member with the peripheral wall, the flow rate of the brake fluid from the reservoir to the pressure chamber may not be increased as desired.

On the other hand, in the master cylinder 11 of the present embodiment, the circumferential groove 32 is located at the inner side in the radial direction from the end of the groove bottom 88 on the cylinder bottom side toward the inner side in the radial direction. It has an inclined portion 91 that is inclined and extends so as to be located at. Therefore, when the hydraulic pressure in the primary pressure chamber 85 decreases and the piston seal 45 is sucked to the primary pressure chamber 85 side and moves to the cylinder bottom side, the outer peripheral lip portion 103 thereof is guided by the inclination of the inclined portion 91 and the radial direction. Transforms inward. Thereby, the communication groove 51 opening to the inclined portion 91 can be communicated between the outer peripheral lip portion 103 and the groove bottom 88, and the flow rate at the time of circulating the brake fluid can be increased.

Further, as a result of increasing the flow rate of the brake fluid flowing in this way, the primary pressure chamber 85 becomes a negative pressure state by the rapid return of the brake pedal, but the port 76 of the primary piston 18 reaches the primary replenishment passage 48. By reaching, the water hammer noise caused by the sudden release of the negative pressure in the primary pressure chamber 85 can be reduced.

Further, the piston seal 45 is arranged at a position where the tip of the outer peripheral lip portion 103 comes into contact with the inclined portion 91 when moved to the cylinder bottom side. Therefore, when the piston seal 45 is sucked to the primary pressure chamber 85 side and moved to the cylinder bottom side, the outer peripheral lip portion 103 is smoothly deformed inward in the radial direction of the circumferential groove 32 by the inclination of the inclined portion 91. Can be made. Thereby, the communication groove 51 opening to the inclined portion 91 can be smoothly communicated with the outer peripheral lip portion 103 and the groove bottom 88, and the flow rate at the time of circulating the brake fluid can be smoothly increased.

When the piston seal 45 moves to the cylinder bottom side, the outer peripheral lip portion 103 falls down with the inclined portion 91 of the circumferential groove 32 as a base point, so that the posture of the piston seal 45 can be stabilized.

Since the communication groove 51 opening to the inclined portion 91 can be communicated between the outer peripheral lip portion 103 and the groove bottom 88 as described above, a passage for forming a flow path is formed at the tip of the intermediate lip portion 104 of the piston seal 45. It is not necessary to form a groove, and the strength of the intermediate lip portion 104 can be improved.

In the above embodiment, the seal structure portion on the primary side including the piston seal 45, the circumferential groove 32 and the communication groove 51 of the cylinder body 15, the concave portion 75, and the first cylindrical portion 71 having the port 76. Although detailed description has been made by taking SP as an example, the piston seal 35 having the same shape as the piston seal 45, the peripheral groove 30 and the communication groove 41 having the same shape as the peripheral groove 32 and the communication groove 51, the recess 75 and the port 76 having the same shape. The secondary side seal structure portion SS including the concave portion 59 and the port 60 also operates in a similar structure. Therefore, the seal structure portion SS has the same effect as the seal structure portion SP.

In the above embodiment, the piston seals 35 and 45 having an E-shaped cross section having the base portion 101, the inner peripheral lip portion 102, the outer peripheral lip portion 103, and the intermediate lip portion 104 have been described as an example. It is also effective when using a piston seal having a base portion, an inner peripheral lip portion, and an outer peripheral lip portion and having a C-shaped cross section without an intermediate lip portion.

According to the first aspect of the above-described embodiment, the master cylinder has a bottomed cylindrical shape with one side being an opening and the other side being a bottom, and has a discharge passage for the brake fluid and a supply passage communicating with the reservoir. A cylinder body having the piston, a piston that is movably arranged in the cylinder body and forms a pressure chamber for supplying hydraulic pressure from the discharge passage between the cylinder body, and a circumferential groove formed in the cylinder body. A seal member is provided inside which can seal between the replenishment passage and the pressure chamber. The seal member includes a base portion that can come into contact with a peripheral wall of the peripheral groove on the side of the opening portion, and an inner peripheral lip portion that extends from the base portion toward the bottom portion and is in sliding contact with the outer periphery of the piston. An outer peripheral lip portion that extends from the base portion toward the bottom portion and contacts the groove bottom of the peripheral groove. The circumferential groove has an inclined portion that inclines radially inward from the end of the groove bottom on the bottom side so that the inner side in the radial direction is located closer to the bottom side. A groove is formed in the cylinder body, the groove opening to the inclined portion and extending from the circumferential groove toward the bottom portion toward the pressure chamber. This makes it possible to increase the flow rate when the brake fluid flows.

According to a second aspect, in the first aspect, the seal member may be arranged at a position where the tip of the outer peripheral lip portion comes into contact with the inclined portion when moved to the bottom portion side. This makes it possible to smoothly increase the flow rate when the brake fluid flows.

According to the master cylinder described above, it is possible to increase the flow rate when the brake fluid flows.

11 Master Cylinder 12 Reservoir 13 Bottom 15 Cylinder Body 16 Opening 18 Primary Piston
19 Secondary piston (piston)
26 Secondary discharge path (discharge path)
27 Primary discharge path (discharge path)
30, 32 Circumferential groove 35, 45 Piston seal (seal member)
38 Secondary supply path (supply path)
41,51 communication groove (groove)
48 primary supply path (supply path)
68 Secondary pressure chamber (pressure chamber)
85 Primary pressure chamber (pressure chamber)
88 groove bottom 89 peripheral wall 91 inclined part 101 base part 102 inner peripheral lip part 103 outer peripheral lip part

Claims (2)

A cylinder body having a bottomed tubular shape having a first side as an opening and a second side as a bottom, and having a brake fluid discharge passage and a supply passage communicating with a reservoir;
A piston that is movably arranged in the cylinder body and that forms a pressure chamber that supplies a hydraulic pressure from the discharge path between the piston and the cylinder body;
A seal member provided in a circumferential groove formed in the cylinder body and capable of sealing between the supply passage and the pressure chamber;
Equipped with
The seal member is
A base portion capable of abutting on the peripheral wall of the peripheral groove on the side of the opening,
An inner peripheral lip portion that extends from the base portion toward the bottom portion and is in sliding contact with the outer periphery of the piston;
An outer peripheral lip portion that extends from the base portion toward the bottom portion side and contacts the groove bottom of the peripheral groove,
The circumferential groove has an inclined portion that is inclined from the end portion of the groove bottom on the bottom side toward the inner side in the radial direction so as to be positioned closer to the bottom side toward the inner side in the radial direction,
A master cylinder having a groove formed in the cylinder body, the groove opening to the inclined portion and extending from the circumferential groove toward the bottom portion toward the pressure chamber. The master cylinder according to claim 1, wherein the seal member is arranged at a position where the tip of the outer peripheral lip portion abuts the inclined portion when the seal member moves to the bottom side.

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