JPH07186932A - Master cylinder - Google Patents

Abstract

PURPOSE:To offer a master cylinder capable of preventing a sealing member from being assembled reversely as well as to improve accuracy of eccentricity of a piston to a cylinder holes while reducing machining manhours. CONSTITUTION:Regarding a master cylinder equipped with a piston 5 having its head part 6 fitted slidably in a cylinder hole 2 formed in a cylinder body 1 and partitioning a liquid pressure chamber A, a shaft part 5A extending from the head part 6 of the piston 5 toward the outer side of the cylinder hole 2, and a cylindric guiding member 20 arranged between the shaft part 5A and the cylinder hole 2 and stopped from slipping out by a slip-out stopper 40 provided on the end of the cylinder hole 2 opening, the cylinder hole 2 bore where the guiding member 20 is arranged and the cylinder hole 2 bore where the head part 6 of the piston 5 slides are of identical diameters. A collar part 25 is provided on the outside circumference of the end of the cylinder hole 2 opening of the guiding member 20 and the collar part 25 is made to abut on a taper part 3 formed on the end of the cylinder hole 2 opening.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a master cylinder used for a hydraulic brake or clutch of a vehicle.

[0002]

2. Description of the Related Art A master cylinder of this type has a large-diameter portion formed through a step at the opening of a cylinder hole and has a piston head as disclosed in Japanese Utility Model Laid-Open No. 4-45166. The part guides the sliding of the cylinder hole and the shaft part guides the large diameter part. Further, by disposing a sealing member having an outer peripheral lip elastically contacting the large diameter hole portion of the guide member and an inner peripheral lip elastically contacting the piston shaft portion in the large diameter hole portion of the guide member of the guide device, the guide member and the piston The space between the shaft and the shaft is sealed.

[0003]

In this conventional master cylinder, the guide device is arranged in a large diameter portion formed to have a diameter larger than that of the cylinder hole through which the head of the piston is guided. In addition to variations in eccentricity accuracy with the large-diameter portion, variations in eccentricity accuracy between the outer periphery of the guide member and the hole through which the piston shaft is guided cause the piston to eccentric with respect to the cylinder hole, causing prying, etc. However, there is a problem that the number of man-hours for machining increases because the large diameter hole is formed. Further, since the outer peripheral shape of the guide member is a cylindrical shape having the same diameter in the axial direction, there is a fear that the guide member may be assembled reversely to the cylinder body.

Further, the sealing member for sealing between the piston shaft portion and the guide member is a so-called lip seal having an outer peripheral lip and an inner peripheral lip, and this lip seal can be detected even when mounted upside down. Could not be done, and the master cylinder could not operate normally.

The present invention has been made to solve such a problem, and improves the eccentricity accuracy of the piston and the cylinder hole while reducing the processing man-hours and prevents the reverse assembly of the sealing member. It is an object of the present invention to provide a master cylinder capable of

[0006]

In order to achieve the above object, the master cylinder of the present invention comprises:
The inner diameter of the cylinder hole in which the guide member is arranged is the same as the inner diameter of the cylinder hole in which the head of the piston slides, and a flange is provided on the outer periphery of the end of the opening of the cylinder hole of the guide member. It is abutted on the tapered portion formed at the end.

According to a second aspect of the present invention, the cap is formed with a projection extending toward the base portion of the sealing member and a plurality of leg portions extending toward the guide member and engageable with an annular groove formed on the outer periphery of the guide member. It was done.

[0008]

In the above-described master cylinder of the present invention, in claim 1, the guide member is arranged in the cylinder hole with the same diameter as the inner diameter of the cylinder hole in which the head of the piston slides. The eccentricity with respect to the hole is improved, and extra processing can be omitted for disposing the guide member.

Further, according to the first aspect of the invention, since the guide member is provided with the flange portion capable of contacting the tapered portion of the cylinder hole, the guide member is prevented from being inserted into the cylinder hole from the flange portion side. There is no need to reverse-assemble the guide member into the cylinder hole.

In the present invention, the cap is provided with a projection extending toward the base of the sealing member, and the leg of the cap is provided only when the projection is located beyond the tip of the outer peripheral lip of the sealing member assembled in the guide member. Since the portion engages with the annular groove of the guide member, reverse mounting of the sealing member to the guide member is eliminated.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view showing the vicinity of a cylinder opening of a tandem master cylinder. And a bottomed cylinder hole 2 extending in the axial direction is formed. A taper portion 3 whose diameter increases toward the opening side is formed at the opening end of the cylinder hole 2, and a guide device 4 described later with reference to FIG. 2 is inserted therein.

A head portion 6 of a piston 5 is slidably housed in the cylinder hole 2, and the bottom side of the cylinder hole 2 (not shown).
A hydraulic chamber A is defined in the shaft chamber 5. A shaft portion 5A of a piston 5 that is reduced in diameter from the head portion 6 slidably penetrates the guide device 4 and extends outside the cylinder body 1. Reference numeral 9 is a through hole having one end opened in the cylinder hole 2 and is connected to the reservoir connecting portion 1
0 to the hydraulic fluid reservoir (not shown). Reference numeral 11 is a loosening hole that opens to the hydraulic chamber A.

A small diameter portion 5B projects from the end surface of the head portion 6 of the piston 5 toward the bottom side of the cylinder hole 2, and a lip seal 12 is fitted to the small diameter portion 5B.

A piston 5 is provided on the bottom side of the cylinder hole 2.
And another piston that divides hydraulic chamber A (not shown)
Is stored slidably, and both pistons have return springs 1.
The spring force of 4 urges the springs 4 in directions away from each other, and the bolt 15 regulates the maximum separation distance.
Reference numeral 16 is a spring receiving plate interposed between the return spring 14 and the small diameter portion 5B of the piston 5.

Next, details of the guide device 4 in FIG. 1 will be described with reference to FIG.

FIG. 2A is an enlarged view of a main part when the sealing member is normally assembled to the guide member, and FIG. 2B is an enlarged view of a main part when the sealing member is reversely assembled to the guide member. .

In FIG. 2A, a guide device 4 includes a guide member 20 and a sealing member 2 assembled to the guide member 20.
1 and a cap 22, and this guide member 20
Is a cylindrical body in which a large-diameter portion 23 having the same diameter as the inner diameter of the cylinder hole 2 and a small-diameter portion 24 are connected to the large-diameter portion 23 via a step portion 23A. A flange portion 25 that projects radially outward is integrally formed at the axial end portion, and an annular groove 26 is formed in the small diameter portion 24 on the outer peripheral step portion 23A side. Reference numeral 27 is a seal member fitted in an annular groove formed on the outer circumference of the large diameter portion 23.

The sealing member 21 is made of an elastic material such as synthetic rubber, and has a circular thick base 30 and the base 3.
0 has an outer peripheral lip 31 projecting from the outer periphery in the axial direction,
On the inner peripheral side of the base 30, an inner peripheral lip 32 is provided which extends coaxially with the outer peripheral lip 31 and is slightly shorter than the outer peripheral lip 31. The sealing member 21 is fitted in a recess 20A that opens toward the small diameter portion 24 side of the guide member 20 so that the tips of the lips 31 and 32 face the opening side of the recess 20A, and the base 30 is recessed in the recess 20A. The outer peripheral lip 31 is elastically contacted with the inner periphery of the recessed portion 20A while engaging with the bottom 20a.

The cap 22 is made of, for example, a synthetic resin, and as shown in FIG. 3A, an annular plate portion 35A having a diameter slightly smaller than the large diameter portion of the guide member 20 and a periphery of the annular plate portion 35A. And a plurality of leg portions 35B extending in the axial direction at a predetermined interval in the direction, and at the tip of the leg portion 35B,
A protrusion 35C engageable with the annular groove 26 of the guide member 20 is formed so as to protrude radially inward. Also, the annular plate portion 3
5A is provided with a plurality of protrusions 35D that extend in the same direction as the leg portions 35B at a predetermined distance in the circumferential direction from the inner circumference. Furthermore, the cap 35 has a structure shown in FIG.
As shown in (b), a plurality of slits 36 extending in the radial direction are formed on the opposite side of the leg portions 35B of the annular plate portion 35A at positions corresponding to the leg portions 35A.

As shown in FIG. 2 (a), the cap 22 is deformed from the side of the leg portion 35B so that each leg portion 35B is radially outwardly expanded, and the small diameter portion 2 of the guide member 20 is deformed.
4, and the protrusion 35C of each leg 35B is attached to the annular groove 26.
By being engaged with the guide member 20, the protrusion 35D of the cap 22 is attached to the sealing member 2 at this time.
The outer peripheral lip 31 is located in the outer peripheral lip 31 beyond the tip of the outer peripheral lip 31. As a result, as shown in FIG. 2 (b), the sealing member 21 is assembled in a state opposite to that shown in FIG. 2 (a), that is, the tip of the outer peripheral lip 31 is engaged with the bottom 20 a of the recess 20. Even if each leg portion 35A is fitted onto the small-diameter portion 25 so that the leg portion 3 can be assembled to the guide member 20,
Before the projection 35C of 5A engages with the annular groove 26 of the small diameter portion 24, the projection 35D abuts the baize 30 of the sealing member 21 to make the assembly impossible.

As shown in FIG. 1, the guide device 4 in which the sealing member 21 and the cap 22 are assembled to the guide member 20 in this manner, as shown in FIG.
The outer peripheral portion 32 of the sealing member 21 is elastically contacted with the shaft portion 5A of the piston 5, and the large diameter portion 23 of the guide member 20 is fitted into the cylinder hole 2 so that the bottom side of the cylinder hole 2 can be fitted. However, the flange portion 25 of the guide member 20 engages with the tapered portion 3 of the cylinder hole 2 so that the position is determined at the opening end of the cylinder hole 2.

As a result, the sealing member 4 has the cylinder hole 2
The inward movement is restricted and the cylinder hole 2 is centered.

The guide device 4 has a ring-shaped retaining member 40 fitted in a groove formed at the opening end of the cylinder hole 2.
The movement to the cylinder hole 2 is restricted by the
The inside is hermetically sealed, and the maximum movement amount of the piston 5 toward the opening side of the cylinder hole 2 is defined by the engagement with the head 6 of the piston 5. A liquid replenishing chamber B is defined by a slit 36 provided in the cap 22 between the head portion 6 of the piston 5 and the sealing device 4, and a through hole 9 is opened in the liquid replenishing chamber B. ing.

Thus, according to this embodiment, the guide member 2
Since the diameter 0 is set to be the same as the inner diameter of the cylinder hole 2 on which the head 6 of the piston 5 slides, and is fitted in the cylinder hole 2, the accuracy of eccentricity between the piston 5 and the cylinder hole 2 is improved. Therefore, it is possible to omit extra processing for disposing the guide member 20.

Further, since the guide member 20 is provided with the flange portion 25 which can contact the tapered portion 2 of the cylinder hole 2,
Even if the guide member 20 is inserted into the cylinder hole 2 from the flange portion 25 side, the flange portion 25 comes into contact with the taper portion 3, and the guide member 20 enters the cylinder hole 2 from the flange portion 25 side. Since the insertion of the guide member 20 is blocked, the guide member 20 is not reversely assembled into the cylinder hole 5.

Further, the cap 22 assembled to the guide member 20 is provided with a projection 35D extending toward the base 30 of the sealing member 21, and the projection 35D is attached to the inside of the guide member 20 and the tip of the outer peripheral lip 31 of the sealing member 21 is assembled. Since the leg portion 35B of the cap 22 is engaged with the annular groove 26 of the guide member 20 only when it is in a position exceeding
If the sealing member 21 is reversely assembled to the guide member 20,
Assembly of the cap 22 to the guide member 20 is prevented.

[0027]

As described above in detail, according to the master cylinder of the present invention, the guide member is arranged in the cylinder hole with the same diameter as the inner diameter of the cylinder hole in which the head of the piston slides. The accuracy of eccentricity between the piston and the cylinder hole is improved, and extra work can be omitted because the guide member is arranged.

Further, since the guide member is provided with the flange portion capable of contacting the tapered portion of the cylinder hole, the guide member is prevented from being inserted into the cylinder hole from the side of the flange portion, and is guided to the cylinder hole of the guide member. There is no reverse assembly.

Further, the cap assembled to the guide member is provided with a projection extending toward the base of the sealing member, and the projection is provided only when the projection is located beyond the outer peripheral lip tip of the sealing member assembled in the guide member. Since the leg portion of the cap engages with the annular groove of the guide member, if the seal member is reversely assembled to the guide member, the assembly of the cap to the guide member is prevented, and thus the seal member It is possible to prevent reverse assembly to the guide member.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing the vicinity of a cylinder opening of a master cylinder as an embodiment of the present invention.

2A and 2B are views showing the configuration of the sealing device in FIG. 1, wherein FIG. 2A is an enlarged view of a main part when the sealing member is normally assembled to the guide member, and FIG. It is a principal part enlarged view at the time of assembly.

3A and 3B are diagrams showing the configuration of the cap in FIG. 1, in which FIG. 3A is a longitudinal sectional view and FIG.

[Explanation of symbols]

 1 Main body 2 Cylinder hole 5 Piston 5A Shaft part 6 Head 20 Guide member 21 Sealing member 22 Cap 25 Collar part 26 Annular groove 30 Base 31 Outer peripheral lip 32 Inner peripheral lip 35B Leg 35D Protrusion 40 Preventing removal

Claims (2)

[Claims] 1. A cylinder body having a cylinder hole,
A piston whose head is slidably fitted in the cylinder hole to define a hydraulic chamber, a shaft portion extending from the head of the piston toward the outside of the cylinder hole, and between the shaft portion and the cylinder hole A cylinder cylinder having a cylindrical guide member that is arranged in the cylinder hole and is prevented from coming off by the cylinder hole opening end, the cylinder hole inside which the guide member is arranged and the head of the piston slide A master cylinder in which the inner diameter of the hole is the same as that of the guide member, and a flange is provided on the outer periphery of the opening end of the cylinder hole of the guide member, and the flange is brought into contact with the tapered portion formed at the opening end of the cylinder hole. 2. A cylinder body having a cylinder hole,
A piston whose head is slidably fitted in the cylinder hole to define a hydraulic chamber, a shaft portion extending from the head of the piston toward the outside of the cylinder hole, and between the shaft portion and the cylinder hole. A cylindrical guide member which is arranged at the end of the cylinder hole and which is prevented from coming off by an end stop, an annular groove which is formed on the inner circumference of the guide member and in which the head side of the piston is released, and arranged at the annular groove. A sealing member that seals between the guide member and the shaft of the piston; and a cap that is provided on the release side of the annular groove and that restricts movement of the sealing member. A master cylinder having an outer peripheral lip that elastically contacts, an inner peripheral lip that elastically contacts the outer periphery of the shaft portion, and a base portion that connects both lips, wherein the base portion is arranged on the cylinder hole opening side, Of the sealing member Over a protrusion extending toward the scan unit, the master cylinder forming the said outer periphery formed with a groove into engageable plurality of legs of the annular of the guide member extends toward the guide member.