JP5193323B2 - Hydraulic master cylinder for vehicles - Google Patents

Description

  The present invention relates to a hydraulic master cylinder for a vehicle in which a brake of an automobile, a motorcycle, a tricycle, or the like is operated with hydraulic pressure, and more specifically, a plunger having a recess opened on the bottom side of a cylinder hole is provided on the inner periphery of the cylinder hole. The present invention relates to a plunger type hydraulic master cylinder for a vehicle that is slidably inserted into a cylinder hole through a provided cup seal.

  As a hydraulic master cylinder for vehicles, an annular seal groove is formed on the inner peripheral surface of a cylinder hole in which a plunger is movably inserted, and a seal between the cylinder hole and the plunger is slidably sealed in the seal groove. It is widely practiced to fit a cup seal. Generally, the seal groove has a circumferential seal groove bottom surface, a cylinder hole bottom side surface, a cylinder hole opening side surface, and a seal groove opening opened to the plunger side, and the cup seal is a seal groove A base portion disposed on the cylinder hole opening side, an inner peripheral lip portion that extends from the inner peripheral side of the base portion toward the bottom of the cylinder hole, and in which the inner peripheral surface slides on the outer peripheral surface of the plunger, Similarly, an outer peripheral lip portion is provided extending from the outer peripheral side toward the bottom of the cylinder hole and the outer peripheral surface abuts against the bottom surface of the seal groove. In addition, about 1/2 of the outer peripheral side of the base of the cup seal is in contact with the side surface of the cylinder hole opening of the seal groove, and gradually moves away from the side surface of the cylinder hole opening toward the inner periphery about 1/2. The surface pressure adjusting surface is formed of a conical surface intersecting at an acute angle with respect to the radial surface of the cylinder hole, and the surface pressure adjusting surface and the cylinder hole opening side surface are not in contact with each other in the non-operating state. In addition, the inner peripheral portion of the side surface of the cylinder hole opening of the seal groove is chamfered into an R shape and connected to the inner peripheral surface of the cylinder hole, and the base portion of the cup seal is connected between the inner peripheral surface of the cylinder hole and the plunger during operation. There was one which prevented being bitten and eaten in between (see, for example, Patent Document 1).

JP 2010-71406 A

  Although the above-mentioned patent document can suppress biting of the cup seal to some extent by the surface pressure adjusting surface, for example, the above-mentioned patent document is applied to a vehicle hydraulic master cylinder of a brake system equipped with a brake control mechanism. When the hydraulic pressure or the return force of the plunger changes during operation of the brake control mechanism, the cup seal is bitten between the cylinder hole opening side surface of the seal groove and the plunger. There was a fear.

  In addition, the inner peripheral portion of the cylinder groove opening side surface of the seal groove is chamfered into an R shape and connected to the inner peripheral surface of the cylinder hole. Since it is necessary to control the feed amount in the direction with high accuracy, processing takes time. Furthermore, if a corner is formed at a portion where the R-shaped portion and the inner peripheral surface of the cylinder hole are continuous, the cup seal may be damaged at the corner.

  Accordingly, an object of the present invention is to provide a hydraulic master cylinder for a vehicle that can prevent biting of the cup seal and improve the durability of the cup seal.

  In order to achieve the above object, a hydraulic master cylinder for a vehicle according to the present invention is fitted into a bottomed cylinder hole formed in a cylinder body, an annular seal groove provided in the cylinder hole, and the seal groove. A cup seal, and a plunger having a recess that is slidably inserted into the cylinder hole through the cup seal and that opens at the tip, and the seal groove includes a bottom surface of the seal groove in the circumferential direction of the cylinder hole. A cylinder hole bottom side surface, a cylinder hole opening side surface, and a seal groove opening opened to the plunger side, and the cup seal is disposed on the cylinder hole opening side of the seal groove, and the base The inner peripheral lip portion extends from the inner peripheral side toward the cylinder hole bottom, the inner peripheral surface slides on the outer peripheral surface of the plunger, and also extends from the outer peripheral side of the base toward the cylinder hole bottom. In the vehicular hydraulic master cylinder provided with an outer peripheral lip portion whose outer peripheral surface is in contact with the bottom surface of the seal groove, the seal groove is formed by chamfering the inner peripheral portion of the side surface of the cylinder hole opening portion into an R shape. The cup seal has a chamfered portion connected to an inner peripheral surface, and the cup seal is provided with an elastic protruding piece in contact with the side surface of the bottom of the cylinder hole on the distal end side of the inner peripheral lip portion, and on the inner peripheral side of the base portion. A surface pressure adjusting surface formed of a conical surface intersecting at an acute angle with respect to the radial surface of the cylinder hole is formed in a direction gradually separating from the side surface of the cylinder hole opening as it goes to the periphery, and a starting point portion of the surface pressure adjusting surface; The starting portion of the chamfered portion is characterized in that the elastic protruding piece is arranged on the outer peripheral side with respect to the elastic protruding piece abutting portion that abuts on the cylinder hole bottom side surface when not in operation. In addition, the starting portion of the surface pressure adjusting surface and the starting portion of the chamfered portion are the outermost base outer periphery where the base of the cup seal and the cylinder hole opening side surface of the seal groove abut when not operating. It is good if it is arranged between the position in the cylinder radial direction of the side contact portion and the position in the cylinder radial direction of the elastic protruding piece contact portion, and the starting portion of the surface pressure adjusting surface and the chamfered portion It is good also considering the origin part as the same position. Further, the chamfered portion includes the R-shaped portion formed continuously on the side surface of the cylinder hole opening, and the cylinder hole opening from the cylinder hole opening side end of the R-shaped portion toward the inner peripheral surface of the cylinder hole. It is preferable that the portion side includes a tapered portion chamfered in a tapered shape with a gradually decreasing diameter.

  According to the vehicle hydraulic master cylinder of the present invention, when the non-operating state, the starting portion of the surface pressure adjusting surface and the starting portion of the chamfered portion are disposed on the outer peripheral side of the elastic protruding piece contact portion. The length from the starting point of the surface pressure adjustment surface of the cup seal to the outer peripheral surface of the plunger can be increased and formed between the chamfered portion of the seal groove and the surface pressure adjustment surface of the cup seal when not in operation. A large gap can be formed, and the deformation of the cup seal applied with hydraulic pressure can be released to the gap and the stress can be dispersed. Thereby, it can suppress that a cup seal is bitten between the cylinder hole opening side surface of a seal groove, and a plunger, and can improve durability of a cup seal.

  In addition, the starting portion of the surface pressure adjusting surface and the starting portion of the chamfered portion are the outermost contact portion of the outermost base portion where the base portion of the cup seal and the side surface of the cylinder hole opening portion of the seal groove abut when not operating. By disposing the cylinder seal between the position in the cylinder radial direction and the position in the cylinder radial direction of the elastic protruding piece abutting portion, it is possible to prevent the cup seal, to which hydraulic pressure is applied, from collapsing during operation.

  In addition, since the origin of the surface pressure adjustment surface of the cup seal and the base end of the chamfered portion of the seal groove are in the same position, the surface pressure of the cup seal can be reduced when fluid pressure is applied to the cup seal during operation. The adjustment surface is gently deformed along the shape of the chamfered portion of the seal groove, and the deformation of the cup seal can be released into the gap in a good state.

  Further, the chamfered portion is formed with an R-shaped portion continuous to the inner peripheral portion of the side surface of the cylinder hole opening, and further, a tapered portion chamfered in a tapered shape from the R-shaped portion toward the inner peripheral surface of the cylinder hole is formed. Therefore, at the time of braking and at the time of braking release, the surface pressure adjusting surface can be gently deformed along the shape of the chamfered portion, and can escape to the gap between the surface pressure adjusting surface and the chamfered portion. There is no risk of damaging the cup seal.

  Further, the chamfered portion of the seal groove is formed by an R-shaped portion and a tapered portion that is chamfered in a tapered shape from the end point portion of the R-shaped portion toward the inner peripheral surface of the cylinder hole. Becomes easier. In particular, by providing the tool for processing the seal groove with a tapered cutting blade for forming the tapered portion, it becomes easy to manage the feed amount of the blade in the cylinder radial direction, and the workability is improved. In addition, since the R-shaped portion, the tapered portion, and the inner peripheral surface of the cylinder hole can be connected in a state that is as gentle as possible, the biting of the cup seal can be suppressed.

It is sectional drawing of the hydraulic master cylinder for vehicles which shows the 1st form example of this invention. It is a principal part expanded sectional view of the hydraulic master cylinder for vehicles similarly. It is explanatory drawing which shows the process of cutting a seal groove. It is a principal part expanded sectional view of the hydraulic master cylinder for vehicles which shows the 2nd form example of this invention. It is principal part expansion explanatory drawing of the seal groove which shows the 3rd form example of this invention. It is sectional drawing of the hydraulic master cylinder for vehicles which shows the 4th example of this invention.

  1 to 3 are views showing a first embodiment of a hydraulic master cylinder for a vehicle according to the present invention. This hydraulic master cylinder 1 has a bottomed cylinder hole 3 formed in a cylinder body 2, and a union boss part 2 a is formed on the outer side of the upper part of the bottom part 3 a of the cylinder hole 3 in a direction parallel to the central axis CL 1 of the cylinder hole 3. It protrudes and the union hole 4 is formed in this union boss | hub part 2a. A boss portion 2b having a liquid passage hole 5 communicating with the cylinder hole 3 protrudes from the upper portion of the cylinder body 2, and is connected to a reservoir (not shown) via a seal member 6 at the boss portion 2b. A connector 7 is attached. Further, mounting brackets 2c, 2c for mounting the vehicle body project from the lower portion of the cylinder body 2, and a large-diameter hole 9 into which the distal end side of the push rod 8 is inserted is provided on the cylinder hole opening side. A diameter cylinder portion 2d is provided continuously.

  A plunger 10 is slidably inserted into the cylinder hole 3 via a first cup seal 11 and a second cup seal 12, and the first cup seal 11 is located on the cylinder hole bottom side with respect to the liquid passage hole 5. The second cup seal 12 is formed on the inner peripheral surface 3 b of the cylinder hole 3 on the cylinder hole opening side with respect to the liquid passage hole 5 in the first seal groove 13 formed on the inner peripheral surface 3 b of the cylinder hole 3. The second seal grooves 14 are respectively fitted. Further, a replenishment oil chamber 15 that continues to the liquid passage hole 5 is formed on the inner peripheral surface 3 b of the cylinder hole 3 between the first seal groove 13 and the second seal groove 14.

  The plunger 10 is formed in a bottomed cylindrical shape having a recess 10 a that opens to the cylinder hole bottom side, and a hydraulic chamber 16 is defined between the recess 10 a and the bottom 3 a of the cylinder hole 3. A return spring 17 is disposed between the bottom surface of the recess 10a and the bottom surface of the cylinder hole 3 to return the inoperative plunger 10 to a predetermined initial position. One end of the return spring 17 is The other end is seated on the bottom surface of the recess 10 a and the other end is seated on the bottom surface of the cylinder hole 3. Further, a spherical concave portion 10b with which the push rod 8 that pushes the plunger 10 abuts is formed on the outer surface of the plunger 10 on the cylinder hole opening side. Further, a plurality of small-diameter communication ports 10c are formed in the circumferential direction in the circumferential wall of the recess 10a so as to penetrate the inside and outside of the circumferential wall and communicate with the hydraulic chamber 16 and the replenishing oil chamber 15 at the initial position in the non-operating state. ing. In the push rod 8, a hemispherical large-diameter head 8a that contacts the spherical recess 10b is inserted into the cylinder hole 3 from the large-diameter hole 9, and an engaging groove 9a formed on the inner periphery of the large-diameter hole 9 is formed. The retaining ring 18 and the retainer 19 engaged with the retaining ring 19 are prevented from coming off.

  The union hole 4 has an axis formed in parallel with the central axis CL1 of the cylinder hole 3 and is open above the outer peripheral side of the seating surface on which the other end of the return spring 17 on the bottom surface of the cylinder hole 3 is seated. The liquid passage hole 5 is formed in a direction orthogonal to the central axis CL1 of the cylinder hole.

  The first seal groove 13 on the cylinder hole bottom side includes a seal groove bottom surface 13a in the cylinder hole circumferential direction, a cylinder hole bottom side surface 13b, a cylinder hole opening side surface 13c, and a seal groove opening 13d opened on the plunger side. In addition, an R-shaped portion 13e chamfered in an R shape (curved surface) continuously to the cylinder hole opening side surface 13c, and a cylinder hole opening of the R-shaped portion 13e are formed on the inner peripheral portion of the cylinder hole opening side surface 13c. A chamfered portion 13g having a tapered chamfered portion 13f whose diameter is gradually reduced on the cylinder hole opening side toward the inner peripheral surface 3b of the cylinder hole 3 from the portion side end portion is formed.

  The first cup seal 11 on the cylinder hole bottom side includes a base portion 11a disposed on the cylinder hole opening side of the first seal groove 13, and a seal groove opening 13d from the inner peripheral side of the base portion 11a toward the cylinder hole bottom portion. And an inner peripheral lip portion 11b whose inner peripheral surface is in sliding contact with the outer peripheral surface of the plunger 10, and an outer peripheral surface of the tip end portion that is also extended from the outer peripheral side of the base portion 11a toward the bottom of the cylinder hole. Is protruded toward the cylinder hole bottom at equal intervals from the outer peripheral lip side tip of the inner peripheral lip portion 11b at a constant interval in the circumferential direction. A plurality of elastic protrusions 11d whose tips are in contact with the inner periphery of the cylinder hole bottom side surface 13b are provided.

  Further, the base end surface 11e of the base portion 11a facing the cylinder hole opening side surface 13c of the first seal groove 13 has a radial direction of about 1/2 on the outer peripheral side of the base end surface 11e protruding toward the cylinder hole opening portion side. When the first cup seal 11 is fitted into the first seal groove 13, the contact surface 11f is brought into surface contact with a portion on the seal groove bottom surface 13a side which is the outer peripheral side of the cylinder hole opening side surface 13c. Yes. On the other hand, about 1/2 of the radial direction on the seal groove opening 13d side, which is the inner peripheral side of the base end surface 11e, is a direction gradually separating from the cylinder hole opening side surface 13c toward the inner periphery from the contact surface 11f. The surface pressure adjusting surface 11g is a conical surface intersecting at an acute angle with respect to the surface in the radial direction. This surface pressure adjusting surface 11g forms a clearance E1 in a non-contact state with a chamfered portion 13g formed on the inner peripheral side of the cylinder hole opening side surface 13c in the non-operating state of the hydraulic pressure master cylinder 1. In the operating state of the hydraulic master cylinder 1, the base portion 11a is deformed as the hydraulic pressure in the hydraulic chamber 16 increases, so that the chamfered portion 13g on the inner peripheral side of the cylinder hole opening side surface 13c is approximately 1/2. The base end face 11e is formed so as to be in pressure contact with the surface pressure adjusting face 11g which is about ½ of the inner peripheral side.

  The length from the contact surface 11f to the tip of the elastic protrusion 11d is formed to be larger than the length of the first seal groove 13 in the axial direction, and the first cup seal 11 is connected to the first seal. When fitted into the groove 13, the elastic protrusion 11 d comes into contact with the cylinder hole bottom side surface 13 b of the first seal groove 13 in a state where the distal end of the elastic protrusion 11 d is bent toward the inner peripheral plunger. On the other hand, the length dimension from the contact surface 11f to the distal end surface of the outer peripheral lip portion 11c is formed to be smaller than the length dimension in the axial direction of the first seal groove 13, and the first cup seal 11 is moved to the first seal groove. When fitted to 13, the distal end of the outer peripheral lip portion 11c is in a free state, and is structured to bend easily toward the inner peripheral lip portion side so as not to hinder the flow of hydraulic fluid when braking is released.

  Furthermore, the starting point portion P1 of the surface pressure adjusting surface 11g of the first cup seal 11 and the starting point portion P2 of the chamfered portion 13g of the first seal groove 13 are the base portions on the outermost peripheral side of the contact surface 11f when not operating. Between the position L1 in the cylinder radial direction of the outer peripheral side contact portion P3 and the position L2 in the cylinder radial direction of the elastic protrusion piece contact portion P4 where the elastic protrusion piece 11d contacts the cylinder hole bottom side surface 13b, Further, the position in the cylinder radial direction of the starting point portion P2 of the chamfered portion 13g is formed so as to be outside the cylinder radial direction of the position in the cylinder radial direction of the starting point portion P1 of the surface pressure adjusting surface 11g.

  On the other hand, the second seal groove 14 on the cylinder hole opening side includes a seal groove bottom surface 14a in the cylinder hole circumferential direction, a cylinder hole bottom side surface 14b, a cylinder hole opening side surface 14c, and a seal groove opening 14d opened on the plunger side. have. The second cup seal 12 on the cylinder hole opening side fitted into the second seal groove 14 includes a base portion 12a disposed on the cylinder hole opening side of the second seal groove 14 and an inner peripheral side of the base portion 12a. An inner peripheral lip portion 12b that extends toward the bottom of the cylinder hole, the inner peripheral surface of which slides on the outer peripheral surface of the plunger 10, and an outer peripheral surface that extends from the outer peripheral side of the base portion 12a toward the bottom of the cylinder hole. And an outer peripheral lip portion 12c in contact with the seal groove bottom surface 14a. The radial dimension of the inner peripheral lip part 12b and the outer peripheral lip part 12c is formed to be substantially the same thickness, and the dimension from the base part 12a to the tip of the outer peripheral lip part 12c is the axial direction of the second seal groove 14 The length from the base 12a to the tip of the inner peripheral lip 12b is shorter than the length of the second seal groove 14 in the axial direction.

  As shown in FIGS. 1 and 2, the hydraulic master cylinder 1 formed in this way has the communication port 10 c of the plunger 10 than the first cup seal 11 by the elastic force of the return spring 17 when not in operation. Is also held at the initial position located on the cylinder hole opening side, the fluid pressure chamber 16 and the replenishing oil chamber 15 communicate with each other via the communication port 10c, and the fluid passage hole 5, between the reservoir and the fluid pressure chamber 16 is connected. The hydraulic fluid can be circulated through the replenishing oil chamber 15 and the plurality of communication ports 10c. The first cup seal 11 has a base portion 11a that contacts the cylinder hole opening side surface 13c of the first seal groove 13, an inner peripheral lip portion 11b that contacts the outer peripheral surface of the plunger 10, and an outer peripheral lip portion 11c that contacts the bottom surface 13a of the seal groove. At the same time, a gap E1 is formed between the chamfered portion 13g of the first seal groove 13 and the surface pressure adjusting surface 11g of the first cup seal 11. In the second cup seal 12, the base 12a is in close contact with the cylinder hole opening side surface 14c of the second seal groove 14, the inner peripheral lip portion 12b is in close contact with the outer peripheral surface of the plunger 10, and the outer peripheral lip portion 12c is in close contact with the seal groove bottom surface 14a. This prevents the outside air from entering the cylinder bore and the hydraulic fluid from leaking outside.

  At the time of braking, when the push rod 8 pushes the plunger 10 toward the bottom of the cylinder hole, the plunger 10 advances in the cylinder hole 3 toward the bottom of the cylinder hole while compressing the return spring 17, and the communication port 10c is the first cup seal. 11, the hydraulic pressure begins to be generated in the hydraulic pressure chamber 16 from the time when the communication state between the hydraulic pressure chamber 16 and the replenishing oil chamber 15 is interrupted, and the pressurized hydraulic fluid passes through the union hole 4 and brakes. Supplied to the grid. At this time, since the union hole 4 opens at the bottom 3a of the cylinder hole 3, the plunger 10 does not block the union hole 4 during operation, and an expansion groove is provided on the inner peripheral wall of the cylinder hole 3 as in the prior art. Since it is not necessary, when the diameter of the plunger 10 is the same, the stroke amount of the plunger 10 can be reduced, and the axial length of the hydraulic master cylinder 1 can be kept short.

  When the first cup seal 11 is braked, the base portion 11a is deformed to the cylinder hole opening side by receiving the hydraulic pressure from the hydraulic pressure chamber 16 side. However, the first seal groove 13 has the cylinder hole opening side surface 13c to the cylinder hole. A chamfered portion 13g having a gently continuous shape is formed on the inner peripheral surface 3b, and the starting point P1 of the surface pressure adjusting surface 11g of the first cup seal 11 and the starting point P2 of the chamfered portion 13g of the first seal groove 13 are When not in operation, the position L1 in the cylinder radial direction of the outermost peripheral base contact portion P3 on the outermost peripheral side of the contact surface 11f and the elastic protrusion contact with which the elastic protrusion 11d contacts the cylinder hole bottom side surface 13b Since the portion P4 is arranged between the position L2 in the cylinder radial direction, the length from the starting point P1 of the surface pressure adjusting surface 11g to the outer peripheral surface of the plunger 10 can be increased. It is possible to form a large gap E1 formed between the chamfered portion 13g and the surface pressure adjustment surface 11g at movement. As a result, the deformation of the first cup seal 11 to which the hydraulic pressure is applied can be released to the gap E1 and the stress can be dispersed, and the inner peripheral portion of the base 11a of the first cup seal 11 can be dispersed during braking and braking. It is possible to prevent biting between the inner peripheral surface 3b of the cylinder hole 3 and the outer peripheral surface of the plunger 10, and to prevent the plunger 10 from moving smoothly, and the durability of the first cup seal 11 can be prevented. Can be improved. Furthermore, the starting point portion P1 of the surface pressure adjusting surface 11g and the starting point portion P2 of the chamfered portion 13g are a position L1 in the cylinder radial direction of the base outer peripheral side contact portion P3 and a cylinder radial direction of the elastic protrusion piece contact portion P4. By being arranged between the position L2, it is possible to prevent the first cup seal 11 to which the hydraulic pressure is applied during operation from falling down.

  When the braking is released, the plunger 10 returns to the initial position by the elastic force of the return spring 17. At this time, when the plunger 10 moves to the cylinder hole opening side, the outer peripheral lip portion 11c of the first cup seal 11 is bent, so that the hydraulic fluid flows into the hydraulic pressure chamber 16 from the replenishing oil chamber 15 side. When the plunger 10 moves to the cylinder hole opening side and the communication port 10c passes through the first cup seal 11, the hydraulic pressure chamber 16 and the replenishing oil chamber 15 are in communication with each other, and hydraulic fluid is transferred from the reservoir to the hydraulic pressure chamber 16. Therefore, the plunger 10 can be smoothly and reliably returned to the initial position.

  Further, when the vehicle hydraulic master cylinder 1 formed in this way is applied to, for example, a vehicle hydraulic master cylinder of a brake system provided with a brake control mechanism, the hydraulic pressure and plunger 10 can be reduced when the brake control mechanism is operated. Even if the force in the return direction changes, the base portion 11a of the first cup seal 11 can escape into the gap E1 in a good state, and can be prevented from being bitten.

  Next, a method for manufacturing the vehicle hydraulic master cylinder 1 as described above will be described. As shown in FIG. 3, in the cylinder body 2 after casting, the large-diameter hole 9 and the engaging groove 9a are cut on the opening side of the cylinder hole 3, and the inner peripheral surface of the cylinder hole 3 is cut. At the same time, a union hole 4 in the cylinder axial direction is formed in the union boss part 2 a so as to open at the bottom of the cylinder hole 3. Further, the boss portion 2 b is formed with a fluid passage hole 5 in a direction orthogonal to the cylinder axis so as to open in the peripheral wall of the cylinder hole 3. Next, the first seal groove 13 and the second seal groove 14 are cut on the inner peripheral surface of the cylinder hole 3.

  The first sealing groove 13 is cut using a cutting tool 20 as shown in FIG. The cutting tool 20 cuts the seal groove forming blade 20b for cutting the seal groove bottom surface 13a, the cylinder hole bottom side surface 13b, and the cylinder hole opening side surface 13c, the R-shaped portion 13e, and the taper portion 13f at the tip of the rotating shaft 20a. A chamfered portion cutting blade 20c is integrally provided. As shown in FIG. 3 (A), the cutting tool 20 is inserted into the cylinder hole with the rotary shaft 20a parallel to the center axis CL1 of the cylinder hole, as shown in FIG. While rotating the seal groove forming blade 20b and the chamfered portion cutting blade 20c, the seal groove forming blade 20b is moved in the radial direction by a preset distance in the cylinder hole peripheral wall direction, and is moved in the circumferential direction along the inner peripheral surface of the cylinder hole. . As a result, the first seal groove 13, the R-shaped portion 13e that becomes the chamfered portion 13g, and the tapered portion 13f are simultaneously cut at predetermined positions on the inner peripheral surface of the cylinder hole 3.

  In the present embodiment, as described above, the cutting direction of the union hole 4 can be made the same as the cutting direction of the cylinder hole 3. The cutting process can be performed in one process, and the workability can be improved. Furthermore, the cutting process of the first seal groove 13 uses the cutting tool 20 integrally provided with the chamfered part cutting blade 20c for cutting the R-shaped part 13e and the tapered part 13f, whereby the cylinder radial direction of the cutting tool 20 is used. The first seal groove 13 and the chamfered portion 13g can be cut easily and satisfactorily without strictly managing the feed amount, and the cost can be reduced.

  FIGS. 4 to 6 show other embodiments of the present invention. Components that are the same as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 4 shows a second embodiment of the present invention. In this embodiment, the starting point P1 of the surface pressure adjusting surface 11g and the starting point P2 of the chamfered portion 13g are at the same position. Thereby, the surface pressure adjusting surface 11g of the base portion 11a is gently deformed along the shape of the chamfered portion 13g, and the deformation of the base portion 11a can be released to the gap E1 in a good state.

  FIG. 5 shows a third embodiment of the present invention. A chamfered portion 13h provided on the inner peripheral portion of the cylinder hole opening side surface 13c of the present embodiment is formed continuously with the cylinder hole opening side surface 13c. A first tapered portion 13i that is gradually inclined toward the cylinder hole opening side, an R-shaped portion 13k that is chamfered in an R shape (curved surface) continuously to the first tapered portion 13i, and the R-shaped portion It has a second tapered portion 13m that is chamfered in a tapered shape in which the diameter of the cylinder hole opening side gradually decreases from the end of the 13k cylinder hole opening side toward the cylinder hole opening side.

  The R-shaped portion 13k is formed by chamfering an inner portion where the extension line EL1 of the first taper portion 13i intersects with the extension line EL2 of the second taper portion 13m into an R shape. Further, the chamfered portion 13h is cut at the tip of the rotary shaft 20a by a seal groove forming blade 20b for cutting the seal groove bottom surface 13a, the cylinder hole bottom side surface 13b, and the cylinder hole opening side surface 13c, and the first taper portion 13i, Processing can be performed using the cutting tool 20 integrally provided with the chamfered portion cutting blade 20c for cutting the R-shaped portion 13k and the second tapered portion 13m.

  In this embodiment, by providing the first tapered portion 13i, the clearance E1 between the chamfered portion 13h and the surface pressure adjusting surface 11g of the first cup seal 11 is increased, and when the hydraulic pressure is received, The deformation of the base 11a of the 1-cup seal 11 can be favorably released to the gap E1, and the stress can be dispersed.

  FIG. 6 shows a fourth embodiment of the present invention, in which the hydraulic master cylinder 1 has a union boss portion on the upper side of the bottom portion 3a of the cylinder hole 3 in a direction perpendicular to the central axis CL1 of the cylinder hole 3. 2e is formed, and a union hole 21 is formed in the union boss part 2e in a direction perpendicular to the center axis CL1 of the cylinder hole and in a direction parallel to the liquid passage hole 5, and one end of the union hole 21 on one side. Is opened at the bottom 3 a of the cylinder hole 3. In this embodiment, since the direction of cutting of the union hole 21 is the same as the direction of cutting of the liquid passage hole 5, the union hole 21 and the liquid passage hole 5 can be performed in one step. The workability can be improved.

  The present invention is not limited to the above-described embodiments, and can also be applied to a seal groove and a cup seal arranged on the bottom side of a cylinder hole of a tandem hydraulic master cylinder having two plungers. . Further, in the above-described embodiment, the starting portion of the surface pressure adjusting surface and the starting portion of the chamfered portion are arranged at the same position, but the present invention has a good gap between the surface pressure adjusting surface and the chamfered portion. Since it should just be formed, it is not strictly limited to the same position, and may be one in which both starting point portions are arranged in close proximity. Furthermore, the position of the union hole is not limited to the above-described embodiments, and it is sufficient that the union hole is opened to the hydraulic chamber.

  DESCRIPTION OF SYMBOLS 1 ... Hydraulic master cylinder, 2 ... Cylinder main body, 2a ... Union boss | hub part, 2b ... Boss part, 2c ... Car body mounting bracket, 2d ... Large diameter cylindrical part, 3 ... Cylinder hole, 3a ... Bottom part, 3b ... Inner peripheral surface 4 ... Union hole, 5 ... Liquid passage hole, 6 ... Seal member, 7 ... Connector, 8 ... Push rod, 8a ... Large diameter head, 9 ... Large diameter hole, 9a ... Engaging groove, 10 ... Plunger, 10a ... bottomed concave part, 10b ... spherical concave part, 10c ... communication port, 11 ... first cup seal, 11a ... base part, 11b ... inner peripheral lip part, 11c ... outer peripheral lip part, 11d ... elastic protrusion, 11e ... base end face, 11f ... Contact surface, 11g ... Contact pressure adjusting surface, 12 ... Second cup seal, 12a ... Base, 12b ... Inner lip, 12c ... Outer lip, 13 ... First seal groove, 13a ... Bottom of seal groove, 13b ... Cylinder hole bottom side surface, 13c Cylinder hole opening side surface, 13d ... seal groove opening, 13e ... R-shaped portion, 13f ... tapered portion, 13g ... chamfered portion, 13h ... chamfered portion, 13i ... first tapered portion, 13k ... R-shaped portion, 13m ... second Tapered portion, 14 ... second seal groove, 14a ... bottom surface of seal groove, 14b ... side surface of cylinder hole bottom, 14c ... side surface of cylinder hole opening, 14d ... opening of seal groove, 15 ... replenishing oil chamber, 16 ... hydraulic pressure chamber, 17 ... Return spring, 18 ... Retaining ring, 19 ... Retainer, 20 ... Cutting tool, 20a ... Rotating shaft, 20b ... Seal groove cutting blade, 20c ... Chamfered portion cutting blade, 21 ... Union hole

Claims (4)

A bottomed cylinder hole formed in the cylinder body, an annular seal groove provided in the cylinder hole, a cup seal fitted in the seal groove, and slidable in the cylinder hole via the cup seal And a plunger having a recess that opens at the tip, and the seal groove opens to the bottom surface of the seal hole in the circumferential direction of the cylinder hole, the side surface of the cylinder hole, the side surface of the cylinder hole, and the plunger side. The cup seal has a base disposed on the cylinder hole opening side of the seal groove, and extends from the inner peripheral side of the base toward the cylinder hole bottom, and has an inner peripheral surface. Including an inner peripheral lip portion that slides on the outer peripheral surface of the plunger, and an outer peripheral lip portion that extends from the outer peripheral side of the base portion toward the bottom of the cylinder hole and the outer peripheral surface abuts against the bottom surface of the seal groove. In the hydraulic master cylinder for use, the seal groove includes a chamfered portion in which the inner peripheral portion of the side surface of the opening of the cylinder hole is chamfered in an R shape and connected to the inner peripheral surface of the cylinder hole. Provided on the distal end side of the peripheral lip portion is an elastic protrusion that abuts against the cylinder hole bottom side surface, and on the inner peripheral side of the base portion, in the direction of gradually separating from the cylinder hole opening side surface toward the inner periphery, A surface pressure adjusting surface composed of a conical surface intersecting at an acute angle with respect to a radial surface is formed, and the elastic protruding piece is configured so that the elastic projecting piece is not in operation when the surface pressure adjusting surface and the chamfered portion start point are not in operation. A hydraulic master cylinder for a vehicle, wherein the hydraulic master cylinder is arranged on an outer peripheral side with respect to an elastic projecting piece abutting portion that abuts on a cylinder hole bottom side surface. The starting portion of the surface pressure adjusting surface and the starting portion of the chamfered portion are a base outer peripheral side contact of the outermost peripheral side where the base of the cup seal and the side surface of the cylinder hole opening of the seal groove abut when not operating. 2. The hydraulic master cylinder for a vehicle according to claim 1, wherein the hydraulic master cylinder for a vehicle is disposed between a position in the cylinder radial direction of the contact portion and a position in the cylinder radial direction of the elastic protrusion contact portion. 3. The hydraulic master cylinder for a vehicle according to claim 1, wherein the starting point portion of the surface pressure adjusting surface and the starting point portion of the chamfered portion are in the same position. The chamfered portion includes the R-shaped portion formed continuously on the side surface of the cylinder hole opening, and the cylinder hole opening side from the end of the R-shaped portion toward the inner peripheral surface of the cylinder hole. The hydraulic master cylinder for a vehicle according to any one of claims 1 to 3, further comprising a tapered portion chamfered in a tapered shape that gradually decreases in diameter.

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