JP2020037318A - Master cylinder - Google Patents

Abstract

To provide a master cylinder which enables reduction of costs.SOLUTION: A master cylinder includes: a reservoir wall part 41 which is formed enclosing a storage chamber 44 in which a brake fluid is stored and includes an upper part forming an opening 115; a reservoir bottom part 43 formed with a communication hole 63 communicating with a cylinder 40; and a lid part covering the opening 115. In the reservoir wall part 41, a window hole 132 closed by a translucent material is formed. The window hole 132 is disposed on an extension line O2 of a center axis of the communication hole 63.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a master cylinder for a vehicle.

  There is a master cylinder in which a reservoir is integrally provided above a cylinder (for example, see Patent Document 1).

International Publication No. WO 2016/104425

  In the master cylinder, cost reduction is required.

  Therefore, an object of the present invention is to provide a master cylinder that can reduce costs.

  In order to achieve the above object, according to the present invention, a reservoir is formed so as to surround a storage chamber in which brake fluid is stored, a reservoir wall portion having an opening at an upper portion, and a communication hole communicating with a cylinder is formed. A reservoir bottom portion, and a lid portion covering the opening portion, wherein the reservoir wall portion is formed with a window hole closed with a light-transmitting material, and the window hole is formed of the communication hole. The configuration is such that it is arranged on an extension of the central axis.

  ADVANTAGE OF THE INVENTION According to this invention, the master cylinder which can reduce cost can be provided.

It is a top view showing the master cylinder of an embodiment. It is II-II sectional drawing of FIG. 1 which shows the master cylinder of embodiment. It is a top view showing the main part member of the master cylinder of an embodiment. It is a front view showing the main part member of the master cylinder of an embodiment. FIG. 5 is a sectional view taken along line VV of FIG. 3 showing a main body member of the master cylinder of the embodiment. FIG. 3 is a partial cross-sectional view illustrating a main body member, a window member, and a seal ring of the master cylinder of the embodiment.

  A master cylinder according to an embodiment will be described with reference to the drawings. As shown in FIGS. 1 and 2, the master cylinder of the present embodiment is a reservoir-integrated master cylinder 2 in which a reservoir 1 forms a part of the master cylinder 2. The master cylinder 2 is for a straddle-type vehicle such as a motorcycle, a three-wheeled buggy, and a four-wheeled buggy mounted in a state of being exposed to the outside. Here, for convenience of explanation, directions are defined in front, rear, left, right, up and down shown in each figure. The front, rear, left, right, up and down substantially correspond to the state of being attached to the vehicle. The first embodiment is a front wheel braking master cylinder 2 operated by the driver's right hand. The present invention is also applicable to a master cylinder for rear wheel braking and a master cylinder for clutch operated by the driver's left hand, in which case the left and right in the following description are reversed. Further, the present invention is also applicable to a master cylinder for rear wheel braking or a master cylinder for an automobile operated by a driver's foot, and in this case, the axial direction of the cylinder is different from that described below.

  The master cylinder 2 is attached to a mounting part 4 located on the right side of the steering bar 3 shown in FIG. 1 of the vehicle. The steering bar 3 is formed by appropriately bending a cylindrical pipe member, and at least the outer peripheral surface of the mounting portion 4 to which the master cylinder 2 is attached has a cylindrical surface.

  The master cylinder 2 has a main body member 5, a holder 6, a fastening member 7, a brake lever 8, a support member 10, a lid 12, a lid mounting member 13, and a mounting member 14, all of which are made of metal. The master cylinder 2 has a diaphragm 15 made of synthetic rubber.

  The main body member 5 is an integrally molded product formed by casting, and has a shape shown in FIGS. The main body member 5 is arranged on the front side of the mounting portion 4 of the steering bar 3 as shown in FIG. As shown in FIG. 3, the main body member 5 is formed with a mounting seat portion 18 slightly to the right of the center in the left-right direction so as to project rearward. As shown in FIG. 1, the main body member 5 is attached to the steering bar 3 by sandwiching the mounting portion 4 of the steering bar 3 between the attachment seat 18 and the holder 6. The mounting seat 18 and the holder 6 are connected by the fastening member 7 which is two bolts, and sandwich the steering bar 3. It should be noted that only one fastening member 7 is shown because of the relationship shown in a plan view in FIG.

  As shown in FIG. 4, the main body member 5 has a pair of upper and lower plate-like lever support portions 21 and 22 formed on the right side thereof. A through hole 23 shown in FIG. 3 is formed in the lever support portion 21, and a through hole (not shown) is formed in the lever support portion 22 so that their centers are aligned with each other. The brake lever 8 is mounted on the main body member 5 by the support member 10 and the mounting member 14 screwed to the support member 10 in a state of being disposed between the pair of lever support portions 21 and 22.

  The support member 10 is a bolt, and is inserted into a not-shown through hole of the lower lever support portion 22, a not-shown through hole of the brake lever 8, and a through hole 23 of the upper lever support portion 21 shown in FIG. The mounting member 14 which is a nut shown in FIG. 4 is screwed into a portion protruding from the upper lever support portion 21. As a result, the support member 10 rotatably supports the brake lever 8, and the brake lever 8 is connected to the main body member 5 by the support member 10.

  The support member 10 is slightly inclined with respect to the up-down direction so that the upper side is closer to the front side, and the brake lever 8 rotates about the support member 10. The brake lever 8 extends rightward from the main body member 5 along the steering bar 3 in front of the steering bar 3.

  As shown in FIG. 1, the main body member 5 has a rear-view mirror mounting portion (not shown) that projects upward near the boundary between the mounting seat portion 18 and the upper lever support portion 21 as shown in FIG. A mirror mounting part 35 is formed.

  As shown in FIG. 1, the main body member 5 is provided with a cylinder 40 extending leftward from the base end side of the mounting seat 18. The cylinder 40 is disposed in front of the steering bar 3 so as to extend along the axial direction of the mounting portion 4. As shown in FIG. 2, the cylinder 40 is formed at a lower portion of the main body member 5, and a reservoir wall portion 41 is formed from an intermediate portion to an upper portion of the main body member 5. The reservoir wall portion 41 has a tubular shape extending in the up-down direction, and an inner wall 42 of the reservoir wall portion 41 and a reservoir bottom portion 43 closing the cylinder 40 side form a storage chamber 44 for storing brake fluid.

  A cylinder hole 48 is formed in the cylinder 40, whereby the cylinder 40 has a bottomed cylindrical shape having a cylinder cylinder portion 49 and a cylinder bottom portion 50. The cylinder hole 48 is open between the lever support portions 21 and 22. The cylinder hole 48 is formed by the inner peripheral surface of the cylinder tube portion 49 and the bottom surface of the cylinder bottom portion 50, and the reservoir bottom portion 43 forms a part of the cylinder tube portion 49. The cylinder hole 48 has a main hole 51, a fitting hole 52, and an opening hole 53 in order from the cylinder bottom 50 side opposite to the lever support portions 21 and 22. The central axis of the cylinder hole 48 is the central axis O1 of the cylinder 40. Hereinafter, the central axis O1 of the cylinder 40 is referred to as a cylinder axis O1, and the axial direction of the cylinder 40 is referred to as a cylinder axial direction. The cylinder axis O1 extends in the left-right direction and is substantially orthogonal to the front-rear direction and the up-down direction. The cylinder axis O1 is parallel to the axial direction of the mounting portion 4 of the steering bar 3 shown in FIG.

  As shown in FIG. 2, the main hole 51 has the longest axial length in the cylinder hole 48. The fitting hole 52 is formed on the opposite side of the cylinder bottom 50 of the main hole 51, that is, on the right side, and has a larger inner diameter than the main hole 51. The opening hole portion 53 is formed on the opposite side of the fitting hole portion 52 to the cylinder bottom portion 50, and is arranged in the cylinder hole 48 on the opposite side to the cylinder bottom portion 50. The opening 53 has an inner diameter smaller than that of the fitting hole 52.

  A screw hole 55 is formed in the cylinder bottom 50 so as to penetrate the cylinder bottom 50. The screw hole 55 is offset to the side opposite to the reservoir wall portion 41 in the radial direction with respect to the cylinder axis O1 which is the center axis of the cylinder hole 48. The screw hole 55 has a maximum inner diameter smaller than the inner diameter of the main hole 51. A screw of a brake pipe (not shown) is screwed into the screw hole 55. The brake pipe communicates with a wheel cylinder (not shown) of a brake device such as a disc brake provided on the wheel side.

  An inner surface 43a of the reservoir bottom 43 on the storage chamber 44 side is a flat surface parallel to the cylinder axis O1. The inner surface 43a is arranged substantially horizontally. A communication hole 63 and a communication hole 64 for communicating the cylinder hole 48 with the storage chamber 44 are formed in the reservoir bottom 43 so as to open to the inner surface 43a. In other words, communication holes 63, 64 communicating with the cylinder 40 are formed in the reservoir bottom 43. The communication hole 63 is disposed closer to the cylinder bottom 50 in the cylinder axis direction than the communication hole 64, that is, on the left side.

  The master cylinder 2 has a return spring 75, a piston 76, a cup seal 77, an O-ring 78, a retaining ring 79, and a boot 80. The return spring 75, a part of the piston 76, the cup seal 77 and the O-ring 78 are arranged in the main hole 51 of the cylinder hole 48, and the retaining ring 79 is arranged in the fitting hole 52. The return spring 75, the piston 76 and the retaining ring 79 are made of metal, and the cup seal 77, the O-ring 78 and the boot 80 are made of an elastic material such as rubber.

  The piston 76 has a shaft 85, a flange 86, a shaft 87, a flange 88, a shaft 89, a flange 90, a shaft 91, a flange 92, a shaft 93, a shaft 95, and a flange 96. are doing. The piston 76 is inserted into the cylinder hole 48 on the side of the opening hole 53.

  The shaft portion 85 is formed at the end of the piston 76 closest to the cylinder bottom portion 50, that is, the left end. The right flange portion 86 of the shaft portion 85 has a larger diameter than the shaft portion 85, and the right shaft portion 87 has a smaller diameter than the shaft portion 85. The right flange portion 88 of the shaft portion 87 has a larger diameter than the flange portion 86, and the right shaft portion 89 has a smaller diameter than the flange portion 88. The right flange portion 90 of the shaft portion 89 has a larger diameter than the shaft portion 89 and has the same diameter as the flange portion 88, and the right shaft portion 91 has a smaller diameter than the flange portion 90.

  The right flange portion 92 of the shaft portion 91 has a larger diameter than the shaft portion 91 and has the same diameter as the flange portion 88, and the right shaft portion 93 has a smaller diameter than the flange portion 92. The shaft 95 on the right side of the shaft 93 has a smaller diameter than the shaft 93. The right flange portion 96 of the shaft portion 95 has a larger diameter than the shaft portion 95, and is formed at the end of the piston 76 that is closest to the cylinder bottom 50.

  The piston 76 is slidably fitted in the main hole 51 of the cylinder hole 48 at the flange 88, the flange 90, and the flange 92. As a result, the piston 76 is slidably provided on the cylinder 40 and moves in the cylinder axis direction.

  The return spring 75 is a coil spring whose one end in the axial direction has a smaller diameter than the other portion. The return spring 75 abuts on the cylinder bottom 50 at the large-diameter end, and the shaft 85 of the piston 76 is inserted inside at the small-diameter end. The flange 86 is brought into contact with the flange 86.

  The cup seal 77 has a C-shape whose cross section including the central axis is open to one side. The cup seal 77 is arranged between the flanges 86 and 88 of the piston 76 and fitted to the shaft 87. The cup seal 77 has a state in which the opening side is arranged on the flange portion 86 side, the inner peripheral side is held between the flange portions 86 and 88, and the outer peripheral portion is in sliding contact with the inner peripheral surface of the main hole portion 51.

  The O-ring 78 has an O-shaped cross section including the central axis. The O-ring 78 is arranged between the flange portions 90 and 92 of the piston 76 and fitted to the shaft portion 91. The O-ring 78 is held between the flange portions 90 and 92, and the outer peripheral portion slides on the inner peripheral surface of the main hole portion 51.

  The retaining ring 79 has a C shape and is fitted and fixed in the fitting hole 52. The boot 80 has a cylindrical shape, and has one end disposed between the shaft 93 and the flange 96 of the piston 76 and fitted to the shaft 95. The other end of the boot 80 extends to the opening 53 and is fitted to the inner peripheral surface of the opening 53.

  In the cylinder hole 48, the cylinder bottom 50 side of the piston 76 with respect to the O-ring 78 is filled with the brake fluid, and the cup seal 77 is formed by the piston 76 and the portion of the main hole 51 on the screw hole 55 side. A hydraulic chamber 101 communicating with a wheel cylinder (not shown) is formed.

  The O-ring 78 regulates the leakage of the brake fluid from the fluid chamber 102 between the piston 76, the main hole 51, the cup seal 77 and the O-ring 78 to the outside. The communication hole 64, which is a port, allows the liquid chamber 102 to always communicate with the storage chamber 44 regardless of the position of the piston 76. The cup seal 77 divides the hydraulic chamber 101 and the liquid chamber 102.

  The pressing portion 105 of the brake lever 8 is disposed on the opposite side of the cylinder portion 50 of the flange portion 96 of the piston 76. When the brake lever 8 is operated, the pressing portion 105 of the brake lever 8 moves to the cylinder bottom 50 side, that is, the left side, and presses the piston 76 in this direction. Then, the piston 76 and the cup seal 77 move integrally in a direction to narrow the hydraulic pressure chamber 101, and the cup seal 77 passes over the communication hole 63 which is a port. Thus, the communication between the storage chamber 44 and the hydraulic pressure chamber 101 is cut off, and the brake fluid is supplied from the hydraulic pressure chamber 101 to a wheel cylinder (not shown). That is, the operation of the brake lever 8 causes the piston 76 to be propelled in the direction of the cylinder bottom 50 to generate brake fluid pressure.

  When the operation of the brake lever 8 is released, the piston 76 and the cup seal 77 are returned integrally from the cylinder bottom 50 by the urging force of the return spring 75, and the brake fluid of the wheel cylinder is released. Return to the pressure chamber 101.

  Here, when the amount of the brake friction material provided in the brake device (not shown) decreases, the volume of the hydraulic chamber on the wheel cylinder side increases. When the brake lever 8 is not operated, the master cylinder 2 communicates with the storage chamber 44 through the communication hole 63 when the hydraulic pressure chamber 101 is in the operating state. The liquid is discharged from the storage chamber 44 to the hydraulic chamber 101 through the communication hole 63 and replenished.

  As shown in FIG. 3, the reservoir wall portion 41 is disposed on a left side wall portion 111, a front wall portion 112 disposed on a front side, a side wall portion 113 disposed on a right side, and a rear side. The rear wall 114 is formed. The reservoir wall 41 has an opening 115 at an upper portion, and has a shape that opens upward.

  The reservoir wall portion 41 has a rectangular tubular shape, and its inner wall 42 is continuous in a rectangular frame shape. That is, the reservoir wall portion 41 has the inner wall 42 facing the inside surrounding the storage chamber 44 continuously in a square shape. Therefore, the reservoir wall portion 41 is formed by surrounding the storage chamber 44 in which the brake fluid is stored by the inner wall 42 and has an opening 115 at an upper portion. The inner wall 42 has a flat partial inner wall 121 facing the storage chamber 44 side of the side wall 111, a flat partial inner wall 122 facing the storage chamber 44 side of the front wall 112, and a storage chamber 44 side of the side wall 113. It has a flat partial inner wall 123 facing toward the storage chamber 44 side of the rear wall 114 and a flat partial inner wall 124 facing the storage chamber 44 side.

  The partial inner wall 121 has a flat wall surface 121a closest to the storage chamber 44 side. The wall surface 121a is inclined to the upper left so as to enlarge the storage chamber 44 toward the upper side. The partial inner wall 122 has a flat wall surface 122a closest to the storage chamber 44 side. The wall surface 122a is inclined upward and forward so as to enlarge the storage chamber 44 toward the upper side. The partial inner wall 123 has a flat wall surface 123a closest to the storage chamber 44 side. The wall surface 123a is inclined upward to the right so as to enlarge the storage chamber 44 toward the upper side. The partial inner wall 124 has a flat wall surface 124a closest to the storage chamber 44. The wall surface 124a is inclined upward and rearward so as to enlarge the storage chamber 44 toward the upper side.

  The wall surface 121a and the wall surface 123a are opposed to each other at the same height, and are mirror-symmetrical to each other. Therefore, the partial inner wall 121 and the partial inner wall 123 are opposed to each other at the same height, and are mirror-symmetrical to each other.

  The wall surface 122a and the wall surface 124a are opposed to each other with the same height, and are inclined mirror-symmetrically to each other. Therefore, the partial inner wall 122 and the partial inner wall 124 are opposed to each other with the same height, and are inclined in mirror symmetry with each other. The wall surfaces 121a, 122a, 123a, and 124a intersect at the same angle with respect to the inner surface 43a.

  In the circumferential direction of the reservoir wall portion 41, R chamfers that are recessed outward are formed between the wall surfaces 121a, 122a, between the wall surfaces 122a, 123a, between the wall surfaces 123a, 124a, and between the wall surfaces 124a, 121a. Further, an R chamfer recessed outward is formed between each of the wall surfaces 121a, 122a, 123a, and 124a and the inner surface 43a. Therefore, the inner wall 42 of the reservoir wall portion 41 has a shape in which the entire height range does not protrude toward the storage chamber 44 over the entire circumference, in other words, has a shape in which there is no part that protrudes partially. In the present embodiment, the wall surfaces 121a, 122a, 123a, 124a of the partial inner walls 121, 122, 123, 124 are flat surfaces, but the wall surfaces 121a, 122a, 123a, 124a protrude toward the storage chamber 44 side. If not, the central part of each wall surface in plan view may be formed by a curved surface bulging outward.

  As shown in FIG. 5, the main body member 5 is formed with an annular annular convex portion 131 that projects forward, that is, in the opposite direction to the storage chamber 44, at an intermediate position in the vertical direction of the front wall portion 112. In the main body member 5, the inside of the annular convex portion 131 is a window hole 132 penetrating the front wall portion 112. The window hole 132 is a circular hole, and an annular step portion 134 that is recessed radially outward is formed on the outer wall surface 131 a side of the annular convex portion 131 opposite to the storage chamber 44.

  As shown in FIG. 6, the master cylinder 2 has a window member 141 mounted in the window hole 132 of the main body member 5 to close the window hole 132, and an O-ring 142 for sealing a gap between the window hole 132 and the window member 141. And a cylindrical member 147.

  The window member 141 is made of a translucent material, and has a disk-shaped main plate part 145 and a substantially cylindrical tubular part 146 protruding from the main plate part 145 to one side in the axial direction. In the window member 141, the cylindrical portion 146 is fitted to the step portion 134 of the window hole 132 via the cylindrical member 147, and at this time, the O-ring 142 is arranged between the window portion 141 and the bottom of the step portion 134. . The window member 141 is attached so as not to project from the outer wall surface 131a of the annular convex portion 131 to the opposite side to the storage chamber 44 as a whole.

  As described above, the window hole 132 that is closed by the translucent material is formed in the reservoir wall portion 41. In the master cylinder 2, the level of the brake fluid in the storage chamber 44 in the reservoir wall portion 41 is visible through the window member 141 made of a light-transmitting material. An upper limit line indicating the upper limit of the level of the brake fluid and a lower limit line indicating the lower limit of the level of the brake fluid are formed in the window member 141. Thus, the window member 141 constitutes a level indicator of the brake fluid.

  As shown in FIG. 2, the reservoir wall portion 41 has a flat surface shape whose upper end surface is arranged on a plane orthogonal to the vertical direction. As shown in FIG. 3, a female screw hole 151 is formed in the upper part of the side wall part 111 of the reservoir wall part 41 from the upper end surface and perpendicular to the upper end surface. A female screw hole 152 is formed in the upper part of the side wall part 113 of the reservoir wall part 41 from the upper end surface to be perpendicular to the upper end surface.

  The diaphragm 15 shown in FIG. 2 is made of rubber elastic material such as EPDM.

  The lid portion 12 is an integrally molded product formed by casting. The lid portion 12 covers the upper opening 115 of the reservoir wall portion 41, and the lower surface thereof sandwiches the diaphragm 15 with the frame-shaped upper end surface of the reservoir wall portion 41. In other words, the diaphragm 15 is directly held between the reservoir wall 41 of the main body member 5 and the lid 12. As shown in FIG. 1, an entrance hole 161 is formed at the center of the lid 12 in the front-rear direction at the left end, and an entrance hole 162 is also formed at the center of the lid at the front-rear direction. The lid portion 12 has a mirror-symmetrical shape in the front-rear direction, and also has a mirror-symmetrical shape in the left-right direction.

  The lid 12 is screwed to the reservoir wall 41 so as to cover the opening 115 together with the diaphragm 15. A cover mounting member 13 made of one screw is inserted into the inlet hole 161 of the cover 12 and an insertion hole (not shown) of the diaphragm 15 and screwed into the female screw hole 151 of the reservoir wall portion 41, and another one is formed. The lid mounting member 13 is inserted into the inlet hole 162 of the lid 12 and an insertion hole (not shown) of the diaphragm 15 and screwed into the female screw hole 152 of the reservoir wall 41, so that the reservoir wall 41, The diaphragm 15 and the lid 12 are integrated.

  As shown in FIG. 2, the diaphragm 15 partitions the storage chamber 44 into a lower liquid chamber 165 in which brake fluid is stored and an upper air chamber 166. This suppresses the brake fluid in the fluid chamber 165 from directly contacting the outside air, thereby suppressing the absorption of the brake fluid by moisture. The air chamber 166 communicates with the atmosphere and is basically maintained at atmospheric pressure. When the brake friction material (not shown) is reduced and the volume of the hydraulic chamber on the wheel cylinder side is increased, even if the brake fluid is supplied from the hydraulic chamber 165 of the storage chamber 44 to the hydraulic chamber 101 of the cylinder 40, the hydraulic chamber is not changed. The diaphragm 15 is deformed following the fluctuation of the amount of the brake fluid 165 to maintain the inside of the fluid chamber 165 at the atmospheric pressure. That is, the diaphragm 15 is deformed in accordance with the reduction in the volume of the liquid chamber 165 and the expansion of the volume of the air chamber 166.

  The reservoir wall portion 41 and the reservoir bottom portion 43 of the main body member 5, the lid portion 12, the window member 141, the O-ring 142, the tubular member 147, the diaphragm 15, and the two lid portion mounting members 13 are provided on the upper portion of the cylinder 40. The reservoir 1 is provided and stores the brake fluid. Therefore, the reservoir 1 is integrally connected to the master cylinder 2 that supplies the brake fluid to the wheel cylinder. By arranging the master cylinder 2 at a position where the traveling wind directly hits the vehicle, the reservoir 1 receives the flow of the air while the vehicle is traveling on the outside of the reservoir wall 41 and the outside of the lid 12.

  In this embodiment, as shown in FIG. 5, the communication hole 63 is formed in the reservoir bottom 43 so that the window hole 132 is arranged on the extension line O2 of the center axis of the communication hole 63. In other words, the extension line O2 of the central axis of the communication hole 63 passes through the space inside the window hole 132 in the axial direction of the window hole 132. Therefore, the center axis of the communication hole 63 is inclined such that the end on the storage chamber 44 side is closer to the window hole 132 than the end on the cylinder hole 48 side in the direction in which the inner surface 43a expands. Here, the extension line O2 of the center axis of the communication hole 63 may intersect with the center axis of the window hole 132, or may be shifted without intersecting with the center axis of the window hole 132.

  Here, the window hole 132 is formed on the main body member 5 as an integral casting by casting during casting or cutting after casting. A drill D indicated by a two-dot chain line in FIG. 5 is inserted from the prepared pilot hole, and a communication hole 63 is formed in the reservoir bottom 43 from the inner surface 43a to the main hole 51. Since the communication hole 63 is cut by the drill D, the communication hole 63 is a linear hole having a circular cross section orthogonal to the extending direction.

  The communication hole 63 includes a large-diameter hole 171 on the storage chamber 44 side, a small-diameter hole 172 on the cylinder hole 48 side, and a tapered hole 173 therebetween. The large diameter hole 171 and the small diameter hole 172 have an inner peripheral surface formed of a cylindrical surface, and the tapered hole 173 has an inner peripheral surface formed of a tapered surface. The small-diameter hole 172 has a smaller diameter than the large-diameter hole 171, and the tapered hole 173 is smaller on the small-diameter hole 172 side so as to connect them. The communication hole 63 opens to the storage chamber 44 at the large-diameter hole 171, and opens to the cylinder hole 48 at the small-diameter hole 172. In other words, the communication hole 63 communicates with the storage chamber 44 at the largest diameter portion and communicates with the cylinder hole 48 at the smallest diameter portion. The entire axial projection surface of the largest diameter large-diameter hole portion 171 of the communication hole 63 is projected within the range of the window hole 132. The drill D has a stepped shape for simultaneously processing the large-diameter hole 171, the small-diameter hole 172, and the tapered hole 173.

  The communication hole 63 is formed by the drill D, and the center axis is not perpendicular to the inner surface 43a, and the end on the inner surface 43a side is closer to the window hole 132 than the end on the opposite side to the inner surface 43a in the direction in which the inner surface 43a spreads. It is inclined to be closer. As a result, as shown in FIG. 3, the shape of the opening 175 of the large-diameter hole 171 on the inner surface 43 a of the reservoir bottom 43 is longer in the direction in which the window hole 132 is formed from the center of the communication hole 63, as shown in FIG. 3. It has an elliptical shape with axes.

  As shown in FIG. 5, the communication hole 63 has an opening 176 of the small-diameter hole 172 at a position where the distance from the inner surface 43 a of the reservoir bottom 43 is shortest in the cylinder hole 48. In other words, the communication hole 63 has an opening 176 at the position closest to the storage chamber 44 in the cylinder hole 48.

  As shown in FIG. 2, the communication hole 64 has a smaller diameter in a portion arranged on the cylinder hole 48 side than in a portion arranged on the storage chamber 44 side. That is, the communication hole 64 opens to the storage chamber 44 on the large diameter side, and opens into the cylinder hole 48 on the small diameter side. The minimum diameter of the communication hole 64 is larger than the minimum diameter of the communication hole 63, that is, the inner diameter of the small-diameter hole 172. The inner surface 43a, which is a flat surface where the communication holes 63 and 64 of the reservoir bottom 43 are opened, has no portion protruding above the inner surface 43a in the inner area.

  The master cylinder described in Patent Literature 1 is a master cylinder for two wheels, in which the cylinder and the reservoir are integrated. In such a master cylinder, the piston may be moved by operating the brake lever in a state where the reservoir lid and the diaphragm are removed during maintenance such as replacement of the brake fluid. At this time, if the amount of the brake fluid in the storage chamber is small, the brake fluid may squirt from the communication hole and leak to the outside through the opening of the reservoir wall. In order to prevent this, it is necessary to attach a protector for covering the communication hole at the bottom of the reservoir to the bottom of the reservoir, which increases the cost.

  On the other hand, in the master cylinder 2 of the present embodiment, the communication hole 63 formed in the reservoir bottom portion 43 and communicating with the cylinder 40 is provided on the extension line O2 of the central axis of the light transmitting material of the reservoir wall portion 41. The window hole 132 closed by the opening is arranged. Thereby, even if the brake fluid is ejected from the communication hole 63 of the reservoir bottom 43, the brake fluid is directed to the window member 141 attached to the window hole 132, and the brake fluid is supplied to the front of the window member 141 or its surroundings. It will hit the wall 122. Therefore, even if the brake fluid is squirted from the communication hole 63 by operating the brake lever 8 and moving the piston 76 with the lid 12 and the diaphragm 15 removed, the brake fluid is squirted through the opening 115 of the reservoir wall 41. Leakage to the outside is suppressed. Since the communication hole 63 is formed so as not to face the opening 115 but to the reservoir wall 41 to prevent leakage of the brake fluid from the opening 115 to the outside, the protector covering the communication hole 63 may be provided with a reservoir. There is no need to attach to the bottom 43, and the number of parts can be reduced. Therefore, cost can be reduced.

  Further, since it is not necessary to attach the protector to the reservoir bottom 43, it is not necessary to provide a structural portion such as a protrusion for holding the protector on the reservoir bottom 43, and the shape of the inner surface 43a of the reservoir bottom 43 can be simplified. Therefore, the casting cost of the main body member 5 can be reduced, and the weight of the main body member 5 can be reduced.

  Further, since the communication hole 63 is configured such that the window hole 132 of the reservoir wall portion 41 is arranged on the extension line O2 of the center axis, the communication hole 63 is formed by inserting the drill D into the window hole 132. Can be. Therefore, an increase in the processing cost of the communication hole 63 can be suppressed.

  In addition, the communication hole 63 has an elliptical shape in which the opening on the inner surface 43a of the reservoir bottom portion 43 has a long axis extending in the direction in which the window hole 132 is formed from the center of the communication hole 63. The opening area can be increased as compared with the case where the opening is formed in a circular shape.

  In the above description, the case where the reservoir wall portion 41 has a rectangular cylindrical shape has been described as an example, but the reservoir wall portion 41 may have a cylindrical shape.

  In the above description, the cylinder shape, the piston shape, the window member shape, the position to which the brake pipe is connected, and the like are not limited to the structure of the present embodiment. May have any shape and position.

  A first aspect of the above-described embodiment has a cylinder in which a piston propelled by operation of a brake lever is slidably provided, and a reservoir provided in an upper portion of the cylinder and storing brake fluid, The reservoir is formed so as to surround a storage chamber in which the brake fluid is stored, and has a reservoir wall having an opening at an upper portion, a reservoir bottom having a communication hole communicating with the cylinder, and covering the opening. A lid portion, wherein the reservoir wall portion is formed with a window hole closed by a light-transmitting material, and the window hole extends on an extension of a central axis of the communication hole. It is characterized by being arranged.

  According to a second aspect, in the first aspect, the communication hole has an opening shape on the inner surface of the reservoir bottom, the ellipse having a major axis arranged in a direction in which the window hole is formed from the center of the communication hole. It is characterized by being a shape.

Reference Signs List 1 reservoir 2 master cylinder 8 brake lever 12 lid 40 cylinder 41 reservoir wall 43 reservoir bottom 43a inner surface 44 storage chamber 63 communication hole 76 piston 115 opening 132 window hole 141 window member O2 extension of the central axis of communication hole

Claims (2)

A cylinder slidably provided with a piston propelled by operation of a brake lever,
A reservoir provided at an upper portion of the cylinder and storing brake fluid,
The reservoir is
A reservoir wall formed around the storage chamber in which the brake fluid is stored and having an opening at the top,
A reservoir bottom formed with a communication hole communicating with the cylinder,
A lid that covers the opening,
A master cylinder having
A window hole closed by a light-transmitting material is formed in the reservoir wall,
The master cylinder, wherein the window hole is disposed on an extension of a central axis of the communication hole.   2. The master according to claim 1, wherein the communication hole has an elliptical shape in which an opening shape on an inner surface of the bottom of the reservoir has a major axis arranged in a direction in which the window hole is formed from a center of the communication hole. 3. Cylinder.

Images