JPH10244937A - Center valve type master cylinder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the assembling performance related to a center valve in consideration of shortening the length of a master cylinder in the axial direction. To effectively maintain the efficiency of generating the liquid pressure by regulating the movement of a seal ring for a piston. SOLUTION: A center valve is accommodated in a recess 300 of a piston. By setting a cup-like retainer member 90 in the periphery of the piston partitioning the recess 300, the retainer member 90 can be used as a spring receiver for a coil spring 73. The retainer member 90 contains a cylindrical part 920, which is set in the periphery of the piston, and a bottom part 910, which is situated at one end of the cylindrical part 920. In this case, the peripheral part 914 of the inner surface of the bottom part 910 of the retainer member 90 is made abut on the tip end surface 202e of the piston, and moreover a spring receiving part, which supports one end of the coil spring 73, is placed inside the peripheral part 914 in its radial direction. In addition, an inner lip 321 of a sealing ring 32a is supported, by utilizing the neighborhood of the opening part of the retainer member 90.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a center valve type master cylinder used for a hydraulic brake or a clutch system of a vehicle or the like, and more particularly to a technique effective for improving the assemblability around a center valve. .

[0002]

2. Description of the Related Art In general, a valve for communicating and shutting off between a hydraulic chamber inside a cylinder body and an external hydraulic fluid reservoir is essential for a master cylinder. In the center valve type master cylinder, there is a recess at one end of the piston facing the hydraulic chamber, and such a valve is located at the center of the recess. The valve is usually, for example,
As disclosed in Japanese Patent No. 5972, a poppet valve body movable in the axial direction of the cylinder body, and a poppet valve body at the bottom side of the recess,
The poppet valve body includes a valve seat on which the poppet valve body is separated and seated, and a coil spring for urging the poppet valve body toward the valve seat.

[0003] This type of center valve has the advantage that the valve body is less eroded than the conventional type, but has the disadvantage that it has a large number of parts and is cumbersome to assemble. For example, in the technique disclosed in the above publication, one end of a coil spring inside a recess is supported by a poppet valve body, while the other end of the coil spring is supported by a stopper ring fitted in a groove in an inner wall of the recess. I have. However, assembling the stopper ring into a relatively small-diameter recess is inferior in workability.

In the master cylinder, a seal ring must be mounted on the outer periphery of the piston in order to define a hydraulic chamber in a cylinder hole of the cylinder body. Normally, since the seal ring is made of a rubber material, when the seal ring is assembled, the seal ring is mounted in a groove on the outer periphery of the piston while increasing the diameter, and is prevented from coming off by a flange portion adjacent to the groove. However, the work of assembling such a seal ring is not good in workability. Moreover, flanges and stopper rings for retaining or supporting
In order to increase the length of the piston in the axial direction, it is not preferable in terms of shortening the overall length of the master cylinder in the axial direction. Further, the seal ring in the groove may change its posture due to falling down or the like during the stroke of the piston, which may reduce the efficiency of generating the hydraulic pressure. This is because the seal ring is prevented from coming off in the axial direction by the flange, but is only supported by its own elastic force against the piston, so the movement of the seal ring (lip-type seal ring) is restricted. This is because they cannot be sufficiently regulated.

On the other hand, as a center valve type master cylinder of this type, as shown in Japanese Patent Publication No. 5-22828, for example, a cup-shaped retainer member is fitted to the tip of a piston facing a hydraulic pressure chamber. There is another technique in which an internal space for accommodating a center valve is formed between a distal end surface of a piston and a bottom of a cup-shaped retainer member. According to this technique, it is possible to obtain an advantage that it is not necessary to form a recess for accommodating the center valve in the piston itself, and furthermore, the end on the opening side of the cup-shaped retainer member is provided with a piston. Can be used as one spring receiver of a return spring that urges the seal ring to the return position. Further, by preventing the seal ring around the piston from coming off by the end of the retainer member, the seal ring with respect to the piston can be used. It is also possible to obtain an advantage that mounting of the device can be facilitated. However, even in the other technology using the cup-shaped retainer member, since the portion for housing the center valve protrudes from the distal end surface of the piston toward the hydraulic pressure chamber, the substantial length of the piston in the axial direction is longer. And the bottom of the protruding retainer member
In the event of a failure, the cylinder body may hit the bottom of the cylinder body (a so-called bottom bump occurs), possibly damaging the retainer member or the center valve therein. Furthermore, with this technology, the seal ring on the outer periphery of the piston can be prevented from coming off in the axial direction, but the movement of the seal ring with respect to the piston cannot be sufficiently restricted. There is a possibility that the efficiency of the method may be reduced.

[0006]

SUMMARY OF THE INVENTION In the above background, the present invention aims to improve the assemblability around the center valve while taking into account the problem of shortening the length of the master cylinder in the axial direction. The purpose is to solve. Another object of the present invention is to solve the problem of effectively maintaining the efficiency of hydraulic pressure generation by restricting the movement of the seal ring around the piston.

[0007]

According to the present invention, the center valve is housed inside the piston in order to reduce the axial length of the master cylinder. Therefore, the piston
An axially extending recess is formed at one end facing the hydraulic chamber. Then, a cup-shaped retainer member is fitted on the outer periphery of the piston that defines the recess, and the retainer member is used as a spring receiver for the coil spring. The retainer member has a cup shape including a tubular portion that fits on the outer periphery of the piston and a bottom portion located at one end of the tubular portion.Here, the peripheral portion of the inner surface of the bottom portion of the retainer member is a tip surface of the piston. And a spring receiving portion for supporting one end of the coil spring radially inward of a peripheral portion thereof. Therefore, the coil spring has one end supported by the poppet valve body and the other end supported by the retainer member. The coil spring is usually conical. In order to match the axis of the coil spring with that of the poppet valve body, the central portion on the radially inner side of the peripheral portion of the retainer member is raised so as to enter the inside of the recess, for example, the side wall of the raised portion is formed. It is preferable that the guide portion is provided with a function of centering the coil spring on the raised portion.

In order to easily assemble the cup-shaped retainer member to the piston, the cylindrical portion of the retainer member is stepped from one end on the bottom side to the opening on the other end on the opposite side. It is preferable to adopt a stepped shape having a larger diameter. With respect to the stepped retainer member, a portion close to the large-diameter opening can be used as one spring receiver of a return spring that biases the piston to the return position. The retainer member fits into the distal end portion of the piston in an interference fit or pressed state. Therefore, the corresponding distal end of the piston has the same outer shape as the retainer member. A first land portion in which a lip-shaped seal ring for partitioning the hydraulic chamber fits at a position axially away from a front end surface corresponding to an inner surface of a bottom portion of the retainer member at a front end portion of the piston in which the retainer member fits. Yes, a seal ring is mounted on the land. At the time of mounting the seal ring, the operation is easy because it is not necessary to increase the diameter forcibly. Also,
Since a part of the seal ring on the first land is supported by the opening of the cylindrical portion of the retainer member, unnecessary movement of the seal ring can be effectively restricted. At this time, it is more preferable that the second land portion (that is, the flange portion) that is located on the piston at a position farther from the distal end surface and that is adjacent to the first land portion and that fits the inner diameter of the cylinder hole. ) May be provided, and the lip-shaped seal ring may be axially positioned by both the second land portion and the opening of the cylindrical portion of the retainer member.

The cup-shaped retainer member is a press-formed product made of an elastic metal material such as a steel plate. Therefore, although the shape of the retainer member can be set relatively freely, the center portion is connected to the small diameter portion near the bottom in addition to the raised bottom portion via the first bent surface to the small diameter portion. It is preferable to provide a cylinder having a middle diameter portion and a large diameter portion connected to the middle diameter portion via a second bent surface. The second bent surface is at a position near the opening, and is substantially orthogonal to the axial direction,
Moreover, the large diameter portion is substantially parallel to the axial direction, and the large diameter portion and the second bent surface can be configured to support a part of the seal ring. Also, in the cylindrical portion of such a retainer member, the middle diameter portion and the second bent surface portion serve as one spring receiver of the return spring, and furthermore, the portion extending from the first bent surface to the large diameter portion of the cylindrical portion. There are a plurality of slits extending in the axial direction, so that when the return spring is assembled, the middle diameter portion and the large diameter portion of the cylindrical portion are elastically deformed to reduce the diameter by receiving the spring force of the return spring. It would be even better. The slit facilitates the elastic deformation of the retainer member, so that the retainer member can be easily fitted to the distal end of the piston, and also serves as an air vent passage at the step on the outer periphery of the piston, thereby improving the air vent performance.

The present invention is applicable to various master cylinders including a center valve. The master cylinder may be of a clutch type, a brake type, a single type or a tandem type. For tandem type,
In particular, the present invention can be effectively applied to the secondary side.

[0011]

FIG. 1 is an overall sectional view showing a tandem type brake master cylinder according to an embodiment of the present invention. In the tandem type master cylinder 10, the primary portion 100 is a conventional type valve and the secondary portion 200 is a center valve. The master cylinder 10 includes a cylinder body 14 having a cylinder hole 12 having a uniform inner diameter except near the opening.
The front end 14f of the cylinder body 14 is closed, and a secondary piston return spring 162, a secondary piston 202, a primary piston return spring 161 and a primary piston 201 are sequentially arranged from the closed side. A rod is placed. Each of the primary and secondary pistons 201 and 202 has a lip-shaped seal ring 31a, 31b;
a and 32b. Each of these seal rings seals the space between the inner peripheral surface of the cylinder body 14 and each of the pistons 201 and 202, whereby the secondary piston 20
2, the second hydraulic chamber 42 and the primary piston 20
A first pressure chamber 41 is defined in front of the first pressure chamber 41.

A primary-side conventional valve 50 and a secondary-side center valve 70 communicate between the first or second hydraulic chambers 41 and 42 and a hydraulic fluid reservoir 80 located above the cylinder body 14. Is to shut off. Now, when the primary piston 201 is pushed through a push rod (not shown), the lip of the seal ring 31 a of the primary piston 201 closes the opening of the return hole 33 to shut off the valve 50, and the hydraulic fluid enters the first hydraulic chamber 41. Generate pressure. Then, the first hydraulic chamber 41
The secondary piston 202 moves due to the hydraulic pressure of the second hydraulic pressure chamber 42, and a hydraulic pressure is generated in the second hydraulic pressure chamber 42 by the shutoff function of the center valve 70.

The primary side valve 50 is located on the outer periphery of the primary piston 201, while the secondary side center valve 70 is provided with a recess provided at the end of the secondary piston 202 facing the second hydraulic chamber 42. 300 inside. The recess 300 is along the axis of the cylinder body 14 and its inner diameter is substantially uniform from the opening to the bottom. The bottom of the recess 300 is located at the center hole 30 of the piston 202.
2 and subsequent guide hole 303, and piston 2
02 through a side peripheral hole 305 on the outer periphery of the hydraulic fluid reservoir 80.
To the interior of the The guide hole 303 is a hole for receiving the shaft member 307 as a valve opening means, and itself penetrates the piston 202.

In the recess 300, a center valve 70 is provided.
There is a poppet valve body 72 which is the main body of the present invention. Poppet valve 7
2 includes a head portion 72h and a rod portion 72r extending from the head portion 72h. The rod portion 72r fits into the center hole 302 of the piston 202 and is movable in a direction along the axis. A conical coil spring 73 serving as a valve spring is provided in the head portion 72h of the poppet valve body 72.
2 is pushed toward the shaft member 307. Piston 202
The portion surrounding the opening of the center hole 302 constitutes the valve seat 60 on which the poppet valve body 72 sits.

Now, the cup-shaped retainer member 90 is
Lightly press-fit into the outer periphery of the distal end portion of the secondary piston 202 that defines the recess 300,
2 are integrated. FIG. 2 is an enlarged view of a part of the piston 202 in which the retainer member 90 is fitted.
FIG. 3 is a side view of the retainer member 90 viewed from a side orthogonal to the axial direction, and FIG. 4 is a front view of the retainer member 90 viewed from the second hydraulic chamber 42 side. The cup-shaped retainer member 90 is made of a steel plate having a bottom portion 910 orthogonal to the axis and a cylindrical portion 920 substantially parallel to the axis (having a thickness of 0.5 m).
m).

The bottom portion 910 of the retainer member 90 has a disk shape with a diameter of about 13 to 14 mm, and its central portion protrudes toward the opening. The raised portion 912 has a diameter of about 8 mm and a height of about 1.5 mm. Thus, the bottom 910 includes a ring-shaped peripheral portion 914 outside the central raised portion 912. The raised portion 912 is provided with a plurality of communication holes 916 that communicate the inside and outside of the retainer member 90 (particularly, see FIG. 4). Such a bottom portion 910 is configured such that the retainer member 910 is connected to the piston 2.
The peripheral portion 914 contacts the distal end surface 202 e of the piston 202 in a state where the peripheral portion 914 is fitted to the distal end portion of the piston 202. For this reason, the retainer member 90 is surely integrated with the piston 202, and maintains sufficient strength against a bottom strike in the event of an emergency. The large-diameter end of the conical coil spring 73, which is a valve spring, is supported by the inner peripheral portion of the peripheral portion 914 while being guided by the side wall of the raised portion 912. In this case, since the large-diameter end of the conical coil spring 73 is located between the inner wall of the recess 300 of the piston 202 and the side wall of the raised portion 912 of the bottom 90, the opening of the inner wall of the recess 300 is formed. Is preferably chamfered around the periphery of the coil spring 73 so that the end of the coil spring 73 does not bite between the retainer member 90 and the piston 202 during assembly. Although the raised portion 912 slightly enters the inside of the recess 300, even in a non-operating state, it is at a slight distance from the poppet valve element 72 side so as not to hinder the operation of the poppet valve element 72. ing.

On the other hand, a cylindrical portion 920 integral with the bottom portion 910 is
It has a stepped shape in which the diameter gradually increases from one end on the bottom 910 side to the opening. That is, the cylindrical portion 920 of the retainer member 90 has a smaller diameter portion 920 s than the bottom.
And a small-diameter portion 920s, a middle-diameter portion 920m connected via a first bent surface (an inclination angle to the axis is about 30 °) 921, and a middle-diameter portion 920m.
Second curved surface (the inclination angle with respect to the axis is approximately 90 °) 9
And a large-diameter portion 920b that is connected through the second portion 920. Correspondingly, the outer diameter of the tip portion of the piston 202 is also stepped, and the small-diameter portion 202s, the first inclined surface 2021,
This is a shape that continues to the middle diameter portion 202m, the second inclined surface 2022, the large diameter first land portion 203, and further to the flange-shaped second land portion 204. First land 2
Reference numeral 03 denotes a portion where the lip-shaped seal ring 32a fits, and the second land portion 204 is a portion where one surface of the seal ring 32a on the first land portion 203 contacts. The diameter of the first land portion 203 is smaller than the diameter of the corresponding large-diameter portion 920b of the retainer member 90, and the retainer member 90 holds the tip of the inner lip 32i of the seal ring 32a by the second bent surface 922. The large diameter portion 920b presses the side circumference of the inner lip 32i.
On the other hand, the second land portion 204 has the cylinder hole 10
2 and functions as a guide for the piston 202.

The cylindrical portion 920 of the retainer member 90
, The middle diameter portion 920 m and the portion of the second bent surface 922 serve as one spring receiver of the return spring 162. Therefore, the cylindrical portion 920 of the retainer member 90 receives the spring force of the return spring 162 near the opening thereof. Here, the portion near the opening of the cylindrical portion 920 is pressed against the piston 202 using the spring force. Therefore, the large-diameter portion 92 extends from the first bent surface 921 to the cylindrical portion 920.
0b, a slit 95 extending in the axial direction
Two 0s are formed. The two slits 950 are in a positional relationship separated from each other by 180 °. Such a slit 9
50 facilitates elastic deformation of the cylindrical portion 920 of the retainer member 90 and facilitates attachment of the retainer member 90 to the piston 202. In addition, when the return spring 162 is assembled, when the middle diameter portion 920m and the large diameter portion 920b of the cylindrical portion 920 are elastically deformed to reduce the diameter by receiving the spring force of the return spring 162, the slit 950 causes the deformation. It can be performed reliably and an additional pressing force can be effectively applied. Therefore, the retainer member 90 allows the seal ring 32 a
Can effectively support the inner lip 32i. As a result, the seal ring 32a does not fall even during the stroke of the piston 202, and the outer lip 32
By o, the hydraulic chamber 42 can be effectively partitioned.
Further, since the slit 950 also functions as an air bleeding passage for the air that accumulates in the step portion on the outer periphery of the piston 202, there is an advantage that the air bleeding property is improved. Furthermore, the slit 950 also functions as a window for visually confirming the mounting position of the retainer member 90.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing an example of a master cylinder according to an embodiment of the present invention.

FIG. 2 is an enlarged sectional view showing a main part of the master cylinder of FIG. 1 in an enlarged manner.

FIG. 3 is a side view showing an example of a retainer member.

FIG. 4 is a front view of the retainer member of FIG. 3;

[Explanation of symbols]

 Reference Signs List 10 master cylinder 12 cylinder hole 14 cylinder body 201 primary piston 202 secondary piston (piston) 300 recess 32a lip-shaped seal ring 42 second hydraulic chamber (hydraulic chamber) 70 center valve 72 valve body 73 valve spring (coil) Spring) 60 Valve seat 90 Retainer member 910 Bottom part 912 Raised part 920 Cylindrical part 950 Slit

Claims (7)

[Claims] 1. A cylinder body having a cylinder hole extending along an axial direction therein, and a cylinder body slidably inserted into the cylinder hole to define a hydraulic chamber in the cylinder hole together with the cylinder body. A piston, and a valve that communicates with and shuts off the hydraulic pressure chamber and the hydraulic fluid reservoir in response to the movement of the piston in the axial direction; and the piston has one end facing the hydraulic pressure chamber. A center valve type master cylinder in which there is a recess extending in the axial direction and the valve is located at the center of the recess, wherein the valve is movable in the axial direction of the cylinder body. And a coil seat that is located on the bottom side of the recess and separates and seats the poppet valve body, and a coil spring that biases the poppet valve body toward the valve seat. Partition A cup-shaped retainer member including a tubular portion that fits on the outer periphery of the ston and a bottom portion located at one end of the tubular portion, and a peripheral portion of the inner surface of the bottom portion of the retainer member hits the distal end surface of the piston, and A center valve-type master cylinder having a spring receiving portion for supporting one end of the coil spring radially inward of a peripheral portion thereof. 2. A central portion radially inward of a peripheral portion of the retainer member is raised so as to enter the inside of the recess, and the raised portion has a function of centering the coil spring in the axial direction. The master cylinder of claim 1. 3. The cylindrical portion of the retainer member has a stepped shape whose diameter gradually increases from one end on the bottom side to the opening on the other end on the opposite side, and is close to the opening. 3. The master cylinder of claim 1 or 2, wherein the portion is one spring receiver of a return spring that biases the piston to a return position. 4. A lip-shaped seal ring for partitioning the hydraulic pressure chamber is provided at a distal end portion of the piston in which the retainer member fits, at a position away from the distal end surface corresponding to an inner surface of a bottom portion of the retainer member in the axial direction. The master cylinder according to claim 3, wherein there is a first land portion that fits, and a part of a seal ring on the land portion is supported by an opening of a cylindrical portion of the retainer member. 5. A second land portion, which is located on a side of the piston further away from the distal end surface and adjacent to the first land portion, has a second land portion which fits the inner diameter of the cylinder hole. 5. The master cylinder according to claim 4, wherein the seal ring is positioned in the axial direction by an opening of a second land portion and a cylindrical portion of the retainer member. 6. 6. A cylindrical portion of the retainer member includes a small-diameter portion near the bottom, a medium-diameter portion connected to the small-diameter portion via a first bent surface, and a second-diameter portion connected to the medium-diameter portion. And a large-diameter portion connected through the bent surface of
The bent surface is substantially orthogonal to the axial direction, and the large diameter portion is substantially parallel to the axial direction, and the large diameter portion and the second bent surface support a part of the seal ring. The master cylinder of claim 4, wherein 7. The cylindrical portion of the retainer member, wherein the middle diameter portion and the portion of the second bent surface serve as one spring receiver of the return spring, and furthermore, from the first bent surface of the cylindrical portion. A plurality of slits extending in the axial direction are provided at a position reaching the large-diameter portion, and when the return spring is assembled, the slits receive the spring force of the return spring and have a middle-diameter portion and a large-diameter portion of the cylindrical portion. 7. The master cylinder according to claim 6, wherein the portion is elastically deformed to reduce the diameter.