JP2015047975A - Vehicular actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicular actuator which can keep durability of a boot even when a pushrod is activated tilting against a cylinder shaft.SOLUTION: A boot 8 comprises: a telescopic cover part 8a which covers a portion from an aperture of a cylinder hole 2a to a shank 6b of a pushrod 6; a cylinder body attachment part 8b which is provided at an end of the cover part 8a and attached in a cylinder aperture side of a cylinder body 2; and a pushrod attachment part 8c which is provided at the other end of the cover part 8a and attached at the shank 6b of the pushrod 6. The cover part 8a includes: a high rigidity part 8d which has a large diameter and provided in the cylinder body attachment part 8b side; and a low rigidity part 8e which is provided in the pushrod attachment part 8c side, has a smaller diameter than the high rigidity part 8d, and has a lower rigidity than that of the high rigidity part 8d.

Description

  The present invention relates to various hydraulic actuators such as hydraulic cylinders, air cylinders, hydraulic cylinders, slave cylinders, and wheel cylinders that hydraulically actuate brakes and clutches of a traveling vehicle. The present invention relates to the structure of a boot provided so as to prevent intrusion.

  For example, a hydraulic master cylinder is used as an actuator for operating a brake for a rear wheel of a motorcycle.

  In this hydraulic master cylinder, a piston that moves through a cylinder hole by pushing a push rod is inserted into a cylinder hole formed in a vertically long cylinder body, and the cylinder hole opening side of the cylinder body, In some cases, a boot is attached between the shaft portion of the push rod protruding from the opening portion of the hole so that rainwater and dust do not enter the inside of the cylinder hole. This boot is usually provided with an extendable cover that covers from the opening of the cylinder hole to the shaft of the push rod, and a cylinder body mounted on the cylinder hole opening side of the cylinder body. And a push rod mounting portion that is provided on the other end of the cover portion and is mounted on the shaft portion of the push rod (see, for example, Patent Document 1).

JP 2005-271832 A

  However, in the thing of the above-mentioned patent document 1, as the push rod pushes the piston, the push rod mounting portion enters the inside of the cover portion, and accordingly, the push rod mounting of the cover portion is performed. Since the part side is folded inward, due to factors such as the arrangement state of the hydraulic master cylinder on the vehicle body and the layout relationship with other parts, etc., when the push rod operates in a tilted state with respect to the cylinder axis, There is a possibility that the inner peripheral surfaces of the cover part folded back with the push rod being pushed contact each other, and the durability of the boot is lowered.

  Therefore, an object of the present invention is to provide a vehicle actuator that can maintain the durability of a boot even when the push rod is operated in a state of being inclined with respect to the cylinder axis.

  In order to achieve the above object, a vehicle actuator according to the present invention has a piston inserted in a cylinder hole formed in a cylinder body, and a push rod that pushes the piston is moved to the cylinder hole opening side end of the piston. In a vehicle actuator in which an extendable boot is attached between a cylinder hole opening side of the cylinder body and a shaft portion of the push rod protruding from the opening of the cylinder hole, the boot is An extendable cover portion that covers from the opening portion of the cylinder hole to the shaft portion of the push rod, and a cylinder body mounting portion that is provided at one end of the cover portion and is mounted on the cylinder hole opening side of the cylinder body A push rod mounting portion provided at the other end of the cover portion and mounted on the shaft portion of the push rod; The cover portion is provided on the cylinder body side mounting portion side with a large diameter and high rigidity portion, and provided on the push rod mounting portion side and has a smaller diameter and the high rigidity portion. It is characterized by having a low-rigidity part whose rigidity is lower than that of the part.

  Further, it is preferable that a reduced diameter portion having a small cross section in a direction perpendicular to the cylinder axis is formed at an intermediate position in the cylinder axis direction of the high rigidity portion. Further, the high-rigidity portion includes a large-diameter cylindrical portion that is continuous with the cylinder body mounting portion, a first conical portion that gradually decreases in diameter from the large-diameter cylindrical portion toward the reduced-diameter portion, and the reduced-diameter portion. It is preferable that a second conical portion having a gradually increasing diameter is provided, and the low-rigidity portion includes a third conical portion having a gradually decreasing diameter from the second conical portion toward the push rod mounting portion. It is. Further, it is preferable that a rib protruding toward the inner peripheral side is formed on the inner peripheral surface of the cylinder body mounting portion.

  According to the vehicle actuator of the present invention, the cover portion of the boot is provided with a large-diameter high-rigidity portion provided on the cylinder body side mounting portion side and a push rod mounting portion side, and has a smaller diameter than the high-rigidity portion. In addition, by providing a low-rigidity part that is less rigid than the high-rigidity part, the pushrod pushes the piston even if the pushrod may operate with the cylinder shaft tilted. In addition, when the push rod mounting part enters the inside of the cover part, the high rigidity part keeps its shape and deforms so that the low rigidity part enters the inside of the cover part. A gap can be maintained between the inner peripheral surfaces, the inner peripheral surfaces of the boots can be prevented from contacting each other, and the durability of the boots is not reduced.

  In addition, since the reduced-diameter portion having a small cross section in the direction orthogonal to the cylinder axis is formed at the intermediate position in the cylinder axial direction of the high-rigidity portion, the boot has a bent shape formed by the reduced-diameter portion. Since the rigidity around the shape is increased, the rigidity of the high-rigidity portion can be ensured and the high-rigidity portion can be easily formed. Further, the high-rigidity portion includes a large-diameter cylindrical portion that is continuous with the cylinder body mounting portion, a first conical portion that gradually decreases in diameter from the large-diameter cylindrical portion toward the reduced-diameter portion, and gradually and continuously with the reduced-diameter portion. The second cone portion having a large diameter and the low-rigidity portion has a third cone portion that gradually decreases in diameter from the second cone portion toward the push rod mounting portion, so that the high rigidity is obtained by changing the shape. The portion and the low rigidity portion can be easily formed. In addition, since the rib that protrudes toward the inner periphery is formed on the inner peripheral surface of the cylinder body mounting part, the rib contacts the cylinder hole opening side of the cylinder body even if the boot is inclined. Since the maintained state is maintained, the sealing performance of the cylinder body mounting portion can be ensured.

It is II sectional drawing of FIG. It is a front view of a hydraulic master cylinder showing an example of the present invention. It is the principal part expanded sectional view of a hydraulic master cylinder similarly. It is a principal part expanded sectional view of a hydraulic master cylinder when a push rod contacts with a piston in the state where it inclined with respect to a cylinder axis. It is a principal part expanded sectional view of a hydraulic master cylinder at the time of pushing a piston in the state where a push rod inclined with respect to a cylinder axis.

  1 to 5 show an embodiment in which the present invention is applied to a hydraulic master cylinder for a rear wheel brake of a bar handle vehicle such as a motorcycle or a tricycle. The hydraulic master cylinder 1 for the rear wheel has a cylinder hole 2a and a large-diameter hole 2b having a larger diameter than the cylinder hole 2a connected to the upper and lower sides of a vertically long cylinder body 2, and an upper cylinder hole 2a. The piston 3 is inserted so as to be movable. A hydraulic pressure chamber 4 is defined between the bottom wall of the cylinder hole 2a and the tip of the piston 3, and a coil-shaped return spring 5 is contracted in the hydraulic pressure chamber 4 so that the piston is not in operation. 3 is urged in the direction of the large-diameter hole 2 b by the elastic force of the return spring 5. A push rod 6 that presses the piston 3 toward the bottom of the cylinder hole is provided at the base end of the piston 3, and a retaining member 7 that prevents the push rod 6 from being detached is provided in the large-diameter hole 2 b of the cylinder body 2. Is provided. A first fitting groove 2c for fitting one end of the boot 8 is formed on the outer peripheral wall of the large diameter hole 2b of the cylinder body 2.

  The cylinder hole 2a is provided with an output port 2d and a relief port 2e communicating with the hydraulic pressure chamber 4, and a supply port 2g communicating with the replenishing fluid chamber 2f. The output port 2d is connected to the rear wheel via a brake hose. The relief port 2e and the supply port 2g are connected to a reservoir (not shown), respectively, to a brake (not shown). Further, the piston 3 is formed with a hemispherical recess 3a for accommodating the large-diameter head 6a of the push rod 6 on the central axis of the base end.

  The push rod 6 is formed at a shaft portion 6b connected to a yoke 9 pivotally supported at a rear end of a brake pedal serving as a brake operator, and at a tip end of the shaft portion 6b, and has a larger diameter than the shaft portion 6b. The large-diameter head 6a accommodated in the hemispherical recess 3a of the piston 3 is integrally provided, and the outer surface of the distal end of the large-diameter head 6a is formed in a hemispherical shape. The shaft portion 6b includes a large-diameter flange portion 6c at an intermediate portion, and a male screw portion 6d is formed closer to the base end side than the large-diameter flange portion 6c. A nut member 10 having a second fitting groove 10a for fitting the other end of the boot 8 to the outer periphery is screwed to the distal end side of the male screw portion 6d, and the yoke 9 has a nut 11 attached to the proximal end side. It is screwed using. The nut member 10 has a female screw hole 10b screwed into the male screw portion 6d on the base end side and a large diameter hole 10c larger in diameter than the female screw hole 10b on the distal end side, and the large diameter hole 10c and the female screw hole 10b. Is positioned by contacting the large diameter flange portion 6c.

  The boot 8 is provided with an extendable cover portion 8a that covers from the opening of the cylinder hole 2a to the nut member 10 and a first fitting groove 2c that is provided at one end of the cover portion 8a and formed in the cylinder body 2. A cylinder body mounting portion 8b to be attached and a push rod mounting portion 8c which is provided at the other end of the cover portion 8a and is fitted into a second fitting groove 10a formed in the nut member 10 attached to the push rod 6. And have.

  A high rigidity portion 8d having a large diameter and a large thickness is provided on the cylinder body mounting portion 8b side of the boot 8, and a small diameter and a thin shape is formed on the push rod mounting portion 8c side. A low rigidity portion 8e having lower rigidity than the rigid portion 8d is provided. Further, a reduced diameter portion 8f having a small cross section in the direction orthogonal to the cylinder axis CL1 is formed at the intermediate position in the cylinder axis direction of the high rigidity portion 8d. The high-rigidity portion 8d includes a large-diameter cylindrical portion 8g that is continuous with the cylinder body mounting portion 8b, a first conical portion 8h that gradually decreases in diameter from the large-diameter cylindrical portion 8g toward the reduced-diameter portion 8f, and a reduced-diameter portion. The low-cone section 8e includes a third conical section 8j that gradually decreases in diameter from the second conical section 8i toward the push rod mounting section 8c. ing.

  Further, a rib 8k having a circular arc surface at the tip end surface is provided at an intermediate position in the cylinder axial direction of the inner peripheral surface of the cylinder body mounting portion 8b. The push rod mounting portion 8c includes an inner peripheral surface 8m that comes into contact with the outer peripheral wall of the second fitting groove 10a, an inner side surface 8n that comes into contact with the piston side wall of the second fitting groove 10a, and an opposite side of the second fitting groove 10a. An outer surface 8p abutting against the piston side wall, and an annular recess 8q is formed on the outer peripheral side of the outer surface 8p, and the push rod mounting portion 8c and the low-rigidity portion 8e are continuous through the annular recess 8q. ing. Further, the outer diameter of the push rod mounting portion 8c is formed to be smaller than the inner diameter of the portion having the smallest diameter of the high rigidity portion 8d.

  In the hydraulic master cylinder 1, when the brake pedal is not operated, the large-diameter head portion 6 a of the push rod 6 abuts against the retaining member 7 so that the push-back limit of the push rod 6 is restricted. At this time, the boot 8 is in a state in which the push rod mounting portion 8c slightly enters the inside of the low rigidity portion 8e, and the other end side of the low rigidity portion 8e is folded inward. When the brake pedal is operated, the push rod 6 is raised, the hydraulic fluid in the hydraulic pressure chamber 4 is gradually increased, and the pressurized hydraulic fluid is sent from the output port 2d to the rear wheel brake via the brake hose. Activate the wheel brake. Further, when the operation of the brake pedal is released, the piston 3 and the push rod 6 are retracted to the initial position by the elastic force of the return spring 5. At this time, as the push rod 6 moves, the push rod mounting portion 8c moves up and down inside the cover portion 8a as the push rod 6 moves, but the high rigidity portion 8d is a large-diameter cylinder continuous to the cylinder body mounting portion 8b. A portion 8g, a first conical portion 8h that gradually decreases in diameter from the large-diameter cylindrical portion 8g toward the reduced diameter portion 8f, and a second conical portion 8i that gradually increases in diameter continuously from the reduced diameter portion 8f, The low-rigidity portion 8e includes a third conical portion 8j that gradually decreases in diameter from the second conical portion 8i toward the push rod mounting portion 8c, and the high-rigidity portion 8d retains its shape. Even if the rigid portion 8e is folded back to the inside of the cover portion 8a, a gap can be maintained between the inner peripheral surfaces, the inner peripheral surfaces of the boot can be prevented from contacting each other, and the durability of the boot 8 can be improved. Can be maintained.

4 and 5 show that the push rod 6 is tilted with respect to the cylinder axis CL1 due to factors such as the arrangement state of the hydraulic master cylinder 1 on the vehicle body and the layout relationship with other components. The push rod mounting portion 8c enters in an inclined state inside the cover portion 8a during operation, and accordingly, the low-rigidity portion 8e is folded back inside the cover portion 8a. However, the shape of the high-rigidity portion 8d from the cylinder body mounting portion 8b to the reduced diameter portion 8f is maintained, and the low-rigidity portion 8e covers the other end side of the reduced-diameter portion 8f. Folded inside the portion 8a, that is, while deforming so that the low-rigidity portion 8e is folded inside while maintaining the shape of the high-rigidity portion 8d, a gap can be maintained between the inner peripheral surfaces. Yes, the inner peripheral surfaces That you touch it can be suppressed. Furthermore, the first conical portion 8h,
Since the bent shape is formed by the reduced diameter portion 8f and the second conical portion 8i, and the rigidity around the bent shape is increased, the rigidity of the high-rigidity portion 8d can be ensured.

  Further, since the outer surface 8p of the push rod mounting portion 8c is continuous with the low rigidity portion 8e via the annular recess 8q, the push rod mounting portion 8c follows the inclination of the second fitting groove 10a well, The sealability between the push rod mounting portion 8c and the second fitting groove 10a can be maintained. Further, since the rib 8k is formed on the inner peripheral surface of the cylinder body mounting portion 8b, the sealing performance of the cylinder body mounting portion 8b is ensured even when the boot 8 is tilted with the tilt of the push rod 6. be able to. Further, a male screw portion 6d is provided on the shaft portion 6b of the push rod 6, the nut member 10 is screwed to the male screw portion 6d, and the second fitting groove 10a is formed in the nut member 10, whereby the second fitting is achieved. The size of the sealing surface of the groove 10a and the push rod mounting portion 8c can be ensured, and the sealing performance can be improved.

  The present invention can be applied not only to a vertical hydraulic master cylinder but also to a horizontal hydraulic master cylinder as in the above-described embodiment. Furthermore, it can be widely used for various actuators such as a slave cylinder and a wheel cylinder, as well as a hydraulic cylinder and an air cylinder.

  DESCRIPTION OF SYMBOLS 1 ... Fluid pressure master cylinder, 2 ... Cylinder body, 2a ... Cylinder hole, 2b ... Large diameter hole, 2c ... 1st fitting groove, 2d ... Output port, 2e ... Relief port, 2f ... Supply oil chamber, 2g ... Supply Port 3 3 Piston 3a Hemispherical recess 4 Fluid pressure chamber 5 Return spring 6 Push rod 6a Large head 6b Shaft 6c Large flange 6d Male thread 7, retaining member, 8 boot, 8 a cover portion, 8 b cylinder body mounting portion, 8 c push rod mounting portion, 8 d high rigidity portion, 8 e low rigidity portion, 8 f reduced diameter portion, 8 g ... large-diameter cylindrical part, 8h ... first conical part, 8i ... second conical part, 8j ... third conical part, 8k ... rib, 8m ... inner peripheral surface, 8n ... inner side, 8p ... outer side, 8q ... annular Recess, 9 ... Yoke, 10 ... Nut member, 10a ... Second fitting groove, 0b ... female screw hole, 10c ... large-diameter hole, 10d ... stepped portion

Claims (4)

A piston is inserted into a cylinder hole formed in the cylinder body, and a push rod that pushes the piston is movably disposed at an end of the piston on the cylinder hole opening side. In a vehicle actuator in which an extendable boot is attached between a shaft portion of the push rod protruding from the opening portion of the cylinder hole, the boot extends from the opening portion of the cylinder hole to the shaft portion of the push rod. An extendable cover portion that covers the cylinder body, a cylinder body attachment portion that is provided at one end of the cover portion and is attached to the cylinder hole opening side of the cylinder body, and is provided at the other end of the cover portion, A push rod mounting portion mounted on the shaft portion, and the cover portion is provided on the cylinder body side mounting portion side. A high-rigidity portion having a high rigidity in diameter, and a low-rigidity portion provided on the push rod mounting portion side, having a smaller diameter than the high-rigidity portion and lower in rigidity than the high-rigidity portion. A vehicle actuator. 2. The vehicle actuator according to claim 1, wherein a reduced diameter portion having a small cross section in a direction perpendicular to the cylinder axis is formed at an intermediate position in the cylinder axis direction of the high rigidity portion. The high-rigidity portion is continuous with the large-diameter cylindrical portion that is continuous with the cylinder body mounting portion, a first conical portion that gradually decreases in diameter from the large-diameter cylindrical portion toward the reduced-diameter portion, and the reduced-diameter portion. And a second conical portion that gradually increases in diameter, and the low-rigidity portion includes a third conical portion that gradually decreases in diameter from the second conical portion toward the push rod mounting portion. The vehicle actuator according to claim 2. The vehicular actuator according to any one of claims 1 to 3, wherein a rib projecting toward the inner peripheral side is formed on an inner peripheral surface of the cylinder body mounting portion.

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