JP3147809B2 - Master cylinder with double seal ring structure - Google Patents

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 a clutch system of a vehicle or the like, wherein a seal ring on an outer periphery of a piston is provided.
The present invention relates to a master cylinder having a double seal ring structure including an inner O-ring and a resin ring fitted on the outer periphery of the O-ring.

[0002]

BACKGROUND OF THE INVENTION Generally, there is a demand for reducing the overall length of a master cylinder in the axial direction. This is because, by the shortening, a space for mounting the master cylinder required for the vehicle can be reduced, and a wider space for the occupants of the vehicle can be secured.

[0003] From the viewpoint of reducing the overall length of the master cylinder, a conventional master cylinder is preferred. This is because the master cylinder requires a valve mechanism that communicates and shuts off between the hydraulic chamber inside the cylinder body and the external working fluid reservoir, but the conventional type has the simplest valve mechanism configuration. ,
This is because the overall length of the master cylinder can be easily reduced. That is, the conventional valve mechanism connects the seal ring supported on the outer periphery of the piston itself (for example, a groove provided on the outer periphery) with the inside and outside of the hydraulic fluid reservoir through the wall of the cylinder portion of the cylinder body. And a communication hole.

[0004]

In a conventional conventional master cylinder, the seal ring on the outer periphery of the piston is a lip type such as a cup seal. However, the lip-type seal ring has a drawback in that the lip portion is easily damaged by the opening of the communication hole provided in the cylinder body. Therefore, the present inventors have proposed a double seal ring structure including an O-ring on the inner peripheral side and a resin ring fitted on the outer periphery of the O-ring as an improved version of the conventional type (for example, Heisei Heisei). 7
Japanese Patent Application No. 7-321190 filed on November 16, 1996 or Japanese Patent Application No. 8-1984 filed on Jul. 9, 1996
No. 87).

Investigations have been made to further shorten the length of the master cylinder in the axial direction with respect to the master cylinder having such a double seal ring structure, and the following has been found. First, the distance between the end face of the piston facing the hydraulic pressure chamber, the cylinder body, and the bottom is inevitably shortened with the shortening, so that the support point of the return spring on the head side is closer to the head than the end face of the piston. It has to be placed in. This is because it is desirable to set the spring length of the return spring longer than the stroke of the piston in order to ensure the durability of the return spring.

As a method of increasing the length of the return spring,
Technology to reduce the diameter of the bottom end of the piston and insert a return spring between the outer periphery of the piston and the inner wall of the cylinder body, or, for the piston, provide a recess that opens to the hydraulic pressure chamber side, Any of the techniques for inserting a return spring into the recess could be applied. But,
When the return spring is arranged on the outer circumference of the piston as in the former,
The sliding surface of the piston (that is, the inner wall of the cylinder body) may be damaged due to the expansion and contraction of the return spring, and the support point on the head side of the return spring is moved to the head side of the cylinder body. The opening or the like must be provided at a position closer to the head side than the supporting point, and the length of the piston and the length of the cylinder are increased. On the other hand, if the return spring is disposed in the recess at the center of the piston as in the latter case, the return spring can be disposed independently without concern for interference with the seal ring.

[0007] Based on the above study results, an object of the present invention is to provide an advantageous technique for further reducing the axial length of a master cylinder having a double seal ring structure. . Further, in the present invention, 2
Another technique is to provide a technique for supporting the end of the return spring on the head side by using a component of a replenishing valve or a differential pressure reducing means necessary for a heavy seal ring structure. The purpose of.

[0008]

According to a first aspect of the present invention, a master cylinder having a double seal ring structure includes a replenishing valve for replenishing a hydraulic chamber with a fluid.
And F3. F1. The seal ring on the outer circumference of the piston is
A ring and a resin ring that fits around the O-ring. F2. The piston has a recess that opens to the hydraulic pressure chamber side and extends to the head side from the outer periphery of the seal ring, and the support point of the return spring on the head side is closer to the head than the seal ring in the recess. Be located on the side. F3. The piston includes a communication passage connecting the hydraulic fluid reservoir to the hydraulic chamber, and a supply valve for supplying hydraulic fluid from the hydraulic fluid reservoir to the hydraulic chamber through the communication passage. Be located inside a place. The first feature F1 is that the seal ring around the piston
It means a heavy seal ring structure. The inner O-ring made of an elastic material such as rubber seals between the piston and the outer resin ring by its own elastic deformation. Further, the resin ring on the outer periphery receives the elastic force of the O-ring to seal between the resin ring and the inner periphery of the cylinder body. Therefore, the resin ring on the outer periphery can open and close the opening of the communication hole on the cylinder body side, similarly to the lip portion of a general lip type seal ring. In addition, the second feature F2
By disposing the support point on the head side of the return spring in the recess, the return spring does not damage the sliding surface of the piston, and the support point is closer to the head than the seal ring. Means that the spring length of the return spring can be increased while shortening the piston length. Further, the third feature F3 means that the refill valve is located inside the piston recess. With respect to the supply valve in the recess, one of its components can be used as a spring receiver for the return spring. For example, a replenishing valve may be constituted by a holder supported by the piston and a lip-shaped seal ring supported by the holder, and the refill valve holder may also serve as a spring receiver for a return spring.

According to a second aspect of the present invention, when a master cylinder having a double seal ring structure has a negative pressure in a hydraulic chamber and a differential pressure between the master cylinder and a reservoir side, the differential pressure is reduced. This is a mode including a differential pressure reducing means (that is, a means for changing the volume of the hydraulic pressure chamber) which functions to perform the above operation. In the second form,
In addition to the above two features F1 and F2, the following feature F4 is added instead of the feature of F3 in the first embodiment. F4. In the recess of the piston, there is provided a differential pressure reducing means that functions to reduce the differential pressure when a negative pressure is generated in the hydraulic pressure chamber with respect to the reservoir side of the atmospheric pressure. The pressure reducing means receives a pressure on the hydraulic pressure chamber side at one end, and a small piston receiving a pressure on the reservoir side at the other end opposed thereto,
A spring for urging the small piston toward the head of the cylinder body. The negative pressure in the hydraulic chamber tends to occur when the piston is suddenly actuated, and the differential pressure reducing means of the feature F4 reduces the volume of the hydraulic chamber by moving the small piston by the differential pressure. Reduce its differential pressure. Also in the second embodiment, the spring receiver of the return spring and one of the constituent members of the differential pressure reducing means are used, such as using the retainer member serving as the spring receiver of the return spring as the spring receiver of the spring of the differential pressure reducing means. be able to. As a retainer member, a cup-shaped main body portion having a U-shaped cross section that enters the recess of the piston, and an outward flange integrated with the open end of the main body portion and hitting the bottom end surface of the piston. Are preferred. In such a cup-shaped retainer member, the inner wall at the bottom of the main body portion serves as a support point on the head side of the return spring, and the outer wall at the bottom serves as a support point on the bottom side of the spring.

The present invention can be effectively applied to a tandem type master cylinder, particularly to a secondary side, but can also be applied to a primary side or a single type master cylinder.

[0011]

FIG. 1 is an overall sectional view showing a tandem type brake master cylinder according to a first embodiment of the present invention. The tandem master cylinder 10
The primary part 100 is a plunger-type valve, whereas the secondary part 200 is a conventional valve having a double seal ring structure. The master cylinder 10 includes a cylinder body 14 in which a cylinder hole 12 having a uniform inner diameter is formed except for a primary portion 100. The front end 14f of the cylinder body 14 is closed, and the secondary piston return spring 162, the secondary piston 202, and the primary piston return spring 161 are opened from the closed side.
And the primary piston 201 are sequentially arranged, and the booster 2
A push rod (not shown) is arranged via 30.
On the outer periphery of the cylinder body on the outer periphery of the primary piston 201 and the outer periphery of the secondary piston 202 itself, seal rings 31a, 31b;
2a 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 2
02, the second hydraulic chamber 42 and the primary piston 2
A first pressure chamber 41 is defined in front of the first pressure chamber 41.

Plunger-type valve 51 on the primary side
0 and secondary side conventional valve 5
Reference numeral 20 is for communicating and blocking between the first or second hydraulic chambers 41 and 42 and the hydraulic fluid reservoir 70 on the upper part of the cylinder body 14. Now, when the primary piston 201 is pushed through a push rod (not shown), the return hole (or communication hole) 33 provided in the piston 201 is closed by the lip-shaped seal ring 31a, and the valve 5 is closed.
10 is shut off, and a hydraulic pressure is generated in the first hydraulic pressure chamber 41. Further, the spring force of the return spring 161 on the primary side is
Since the spring force is set stronger than the spring force of the return spring 162 on the secondary side, the pressing force applied to the push rod is transmitted to the primary piston 201, and the force is transmitted to the secondary piston 202 via the return spring 161. As a result, the secondary piston 202 also moves almost simultaneously with the primary piston 201, and generates a hydraulic pressure in the second hydraulic chamber 42 by the shutoff function of the valve 520.

The primary side valve 510 is mainly composed of a lip-shaped seal ring 31a, whereas the secondary side valve 520 is a double valve including an inner O-ring 321 and an outer resin ring 322. Seal ring 32
a is the subject. The second hydraulic chamber 4 is provided on the secondary piston 202 supporting the double seal ring 32a.
At the end facing 2 there is a recess 300. The recess 300 is a deep blind hole extending along the axis of the cylinder body 14 and near the other end face. The inside diameter is slightly larger at the opening,
Its depth is almost uniform up to the bottom. Near the bottom of the recess 300, there are a plurality of passage holes 302 communicating between inside and outside, and through these passage holes 302, a side peripheral hole 303 on the outer periphery of the piston 202, and further, through a supply hole 305, through the inside of the hydraulic fluid reservoir 70. Leads to.

FIG. 2 showing the secondary part 200 in an enlarged manner.
As is clear from the figure, in the recess 300 there is a holder 62 that is the body of the refill valve 60. Holder 62
In addition to the first flange portion 621 that fits the inner diameter of the recess 300, there is a second flange portion 622 having a smaller diameter than the first flange portion 621, and the first and second flange portions 622. The flange portions 621 and 622 form a ring groove 623 therebetween. The ring groove 623 is
A mounting groove for mounting and supporting the lip-shaped cup seal 630. The cup seal 630 includes a lip 630
s is directed toward the opening side of the recess 300. The second flange portion 622 having a small diameter is located at a position slightly deeper from the end surface of the holder 62, and the diameter between the end surface and the second flange portion 622 is smaller than that of the second flange portion 622. A small cylindrical portion 624 is formed. Here, the end on the head side of the return spring 162 made of a coil spring is fitted on the outer periphery of the cylindrical portion 624, and the return spring 162 is supported by the second flange 622. The return spring 162 is formed into a so-called cage (basket) by a bolt member 164b fixed to the center of the holder 62 and a cup-shaped retainer 164r guided by the bolt member 164b. The retainer 164r serves as the other spring receiver of the return spring 162. The caged return spring 162 does not fall when the spring expands and contracts.

[0015]

[Modification 1 of First Embodiment] In the embodiment shown in FIG. 2, the second flange portion 622 serving as a spring receiver is integrated with the main body portion of the holder 62, but as shown in FIG.
The main body portion 62b of the holder and the second flange portion 622 can be constituted by different components. Although there is a problem of increasing the number of parts, there is an advantage that the cup seal 630 can be easily mounted.

[0016]

[Modification 2 of the first embodiment] In the embodiment shown in FIG. 2, a cup seal 630 for replenishment is arranged on the outer periphery of the holder 62, but as shown in FIG. A ring groove is provided, and a cup seal 63 is provided in the groove.
0 'can be attached. In that case, holder 6
2 'requires a communication passage 627 for communicating the hydraulic chamber 42 with the outer periphery of the holder 62', and an O-ring 632 for sealing the outer periphery.

[0017]

Second Embodiment FIG. 5 is a sectional view showing a secondary portion of a tandem type brake master cylinder according to a second embodiment of the present invention. While the first embodiment includes a supply valve, the second embodiment shows an example in which a small piston 80 is provided in the recess 300 as a differential pressure reducing means.
The small piston 80 is located at the innermost part of the recess 300 and is movable in the recess 300 in the axial direction. The small piston 80 supports an O-ring 82 on its outer circumference, thereby sealing the opening side and the bottom side of the recess 300. Therefore, the small piston 80 receives the pressure on the hydraulic pressure chamber 42 side at one end, and the hydraulic fluid reservoir 70
Receive side pressure. The small piston 80 is urged toward the bottom by a spring 84 having a small spring force, and one end of the small piston 80 contacts the bottom of the recess 300 in a normal state.
Therefore, when a small differential pressure is generated at the hydraulic pressure chamber 42 with respect to the reservoir side of the atmospheric pressure, the small piston 80 moves the spring 8.
4 while moving so as to decrease the volume of the hydraulic chamber 42 while reducing the pressure difference.

One spring bearing of the spring 84 of the differential pressure reducing means is the small piston 80 itself, and the other spring bearing is
This is a cup-shaped retainer member 90. Retainer member 9
0 includes a main body 92 having a U-shaped cross section and an outward flange 94 located at an open end thereof. In the retainer member 90, a portion of the main body 92 enters the recess 300, but the outward flange 94 contacts the end face of the piston 202 as a stopper, and is integrated with the piston 202. As a result, the retainer member 90 moves the return spring 1 to its inner bottom.
An end of the head 62 on the head side is applied, and serves as one spring receiver for the return spring 162. The return spring 162
The nut 164 is located at the center of the main body 92 of the retainer member 90.
a bolt member 164b fixed with n
Here again, a so-called cage is formed by a cup-shaped retainer 164r guided by b.
The retainer 164r serves as the other spring receiver of the return spring 162, and the caged return spring 162 does not fall even when the spring expands and contracts.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing an example of a master cylinder according to a first 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 an enlarged sectional view of a main part showing a modification of the first embodiment.

FIG. 4 is an enlarged sectional view of a main part showing another modification of the first embodiment.

FIG. 5 is an enlarged sectional view of a main part showing a second embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 10 master cylinder 12 cylinder hole 14 cylinder main body 201 primary piston 202 secondary piston (piston) 300 recess 32a double seal ring 321 O-ring 322 resin ring 42 second hydraulic chamber (hydraulic chamber) 62 holder 630 cup Seal 70 Hydraulic fluid reservoir 80 Small piston 84 Spring 90 Retainer member

Continuation of the front page (56) References JP-A-7-55013 (JP, A) JP-A-6-219263 (JP, A) JP-A-54-130765 (JP, A) JP-A-55-132357 (JP) , A) Fully open sho 56-143156 (JP, U) Fully open sho 55-155668 (JP, U) Fully open sho 57-9657 (JP, U) Tokubo 30-8204 (JP, B1) (58) Field surveyed (Int.Cl. ⁷ , DB name) B60T 11/16 F16D 25/08

Claims (6)

(57) [Claims] 1. A. First Embodiment A cylinder body extending along the axis from the head side to the bottom side inside the cylinder portion, and a cylinder body including a communication hole for penetrating the wall of the cylinder portion and communicating the inside and the outside hydraulic fluid reservoir side; B. B. a piston that supports a seal ring on its outer periphery, slides into the cylinder hole of the cylinder body, and defines a hydraulic chamber in cooperation with the cylinder body; A return spring for applying a return force to the piston from the bottom side of the cylinder body toward the head side; B. input operation means for moving the piston from the head side to the bottom side against the force of the return spring; When the piston is at a predetermined initial position due to the return force of the return spring, the hydraulic chamber communicates with the hydraulic fluid reservoir through the communication hole, and the input operation means causes the piston to move into the cylinder hole. A master cylinder having a double seal ring structure, wherein the seal ring on the outer periphery of the piston closes the communication hole in response to moving inside. F1. The seal ring includes an inner O-ring and a resin ring that fits around the outer periphery of the O-ring. F2. The piston has a recess that opens toward the hydraulic pressure chamber side and extends toward the head side from the seal ring portion,
The head-side support point of the return spring is located closer to the head than the seal ring in the recess. F3. The piston includes a communication passage connecting the hydraulic fluid reservoir and the hydraulic chamber, and a supply valve for replenishing the hydraulic chamber from the hydraulic fluid reservoir to the hydraulic chamber through the communication passage. The valve is located inside said recess. 2. One of members constituting the supply valve also serves as a member for supporting a head side of the return spring.
The master cylinder of claim 1. 3. The supply valve includes a holder supported by the piston and a lip-shaped seal ring supported by the holder, and the holder includes a member for supporting a head side of the return spring. 3. The master cylinder according to claim 2, which also serves as a master cylinder. 4. A. A cylinder body extending along the axis from the head side to the bottom side inside the cylinder portion, and a cylinder body including a communication hole for penetrating the wall of the cylinder portion and communicating the inside and the outside hydraulic fluid reservoir side; B. B. a piston that supports a seal ring on its outer periphery, slides into the cylinder hole of the cylinder body, and defines a hydraulic chamber in cooperation with the cylinder body; A return spring for applying a return force to the piston from the bottom side of the cylinder body toward the head side; B. input operation means for moving the piston from the head side to the bottom side against the force of the return spring; When the piston is at a predetermined initial position due to the return force of the return spring, the hydraulic chamber communicates with the hydraulic fluid reservoir through the communication hole, and the input operation means causes the piston to move into the cylinder hole. A master cylinder having a double seal ring structure, wherein the seal ring on the outer periphery of the piston closes the communication hole in response to moving inside. F1. The seal ring includes an inner O-ring and a resin ring that fits around the outer periphery of the O-ring. F2. The piston has a recess that opens toward the hydraulic pressure chamber side and extends toward the head side from the seal ring portion,
The head-side support point of the return spring is located closer to the head than the seal ring in the recess. F4. In the recess of the piston, there is a differential pressure reducing means that functions to reduce the differential pressure when a differential pressure in which the hydraulic pressure chamber becomes a negative pressure with respect to the atmospheric pressure reservoir side,
The differential pressure reducing means receives a pressure on the hydraulic pressure chamber side at one end and a small piston receiving the pressure on the reservoir side at the other end opposed thereto, and biases the small piston toward the head side of the cylinder body. And a spring that does. 5. The master cylinder according to claim 4, wherein a retainer member for supporting a head side of said return spring also serves as a spring receiver for supporting a spring of said differential pressure reducing means. 6. The retainer member has a U-shaped main body portion having a U-shaped cross section that enters the recess of the piston, and is integrated with an open end of the main body portion, and is outwardly directed to a bottom end surface of the piston. The master cylinder according to claim 5, further comprising a flange, wherein an inner wall at a bottom of the main body portion is a support point on the head side of the return spring, and an outer wall at the bottom is a support point on the bottom side of the spring.