JPH0689850B2 - Seal device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure sealing device, and in particular,
The present invention relates to a technique suitable for use in making a seal between a pressure chamber of a master cylinder and a reservoir.

(Prior Art) Some sealing devices require liquid replenishment in addition to sealing. A typical example is the seal around the piston of the master cylinder, especially the part of the primary cup. The liquid replenishment property of the primary cup is very important from the viewpoint of satisfying functions such as air bleeding, double brake or brake loosening.

In such a sealing device, a lip seal member is used as a component for sealing, and the lip seal member has one lip portion elastically contacting one wall surface and the other lip portion elastically contacting the other wall surface. And a base portion that connects the lip portion. Then, one of the lip portions is deformed from the backup portion side that supports the base portion to allow the movement of the fluid, thereby ensuring the liquid replenishment property. In view of this, conventionally, the lip portion of the lip seal member has a shape that is easily deformed, but the base portion has a constant thickness in order to ensure backup of that portion. Regarding the conventional sealing device of this type,
For example, it is described in JP-B-59-25905.

(Problems to be Solved by the Invention) In a conventional lip seal member having a constant thickness of the base portion, the base portion hinders the deformability of the lip portion, and it is not always possible to secure sufficient liquid replenishment performance. Can not. Therefore,
In order to complement the liquid replenishment property, a groove for liquid replenishment is provided in the connecting portion between the lip portion and the base portion, but this also causes a new problem. The problem is that the length of the lip portion is lengthened or molding is difficult. Particularly, in the master cylinder, if the length of the lip portion is long, the total cylinder length is increased or the lip portion is apt to be damaged.

Therefore, it is an object of the present invention to provide a technique capable of improving the liquid replenishment property without forming a liquid replenishment groove.

(Means for Solving the Problems) In the present invention, the base portion is formed so as to be gradually thinned toward the lip portion that deforms during liquid replenishment, and the deforming lip portion and the base portion The point (E) located at the boundary part of the line is closer to the backup part side as viewed in the axial direction parallel to the wall surface than the intersection point (P) between the deforming lip part and the wall surface on which the lip part elastically contacts. Is set to.

More preferably, the lip portion on the side opposite to the lip portion that is deformed when replenishing the liquid is preferably formed to be thicker than the base portion and the lip portion that is deformed. When the lip portion on the opposite side is divided into two in the axial direction with the boundary point (O) between the lip portion and the base portion as a boundary, the wall surface is more distant from the side closer to the backup portion side. It is better to make strong contact (in other words, the seal part should be located on the far side).

(Working) Since the base part is gradually thinned toward the deforming lip part, the stiffness of the base part becomes weak and the base part itself also deforms as the lip part deforms when replenishing the liquid. The liquid replenishment property is improved. Therefore, the conventional liquid supply groove is not required, and the length of the lip portion can be shortened accordingly. Moreover, since the boundary point (E) between the base portion and the lip portion is set in a predetermined positional relationship with the intersection point (P) between the lip portion side and the wall surface, that and the base portion have a specific taper. Due to the fact that it has a shape, the lip portion is always deformed smoothly while changing the degree of deformation according to the magnitude of the differential pressure between the front and rear. Also, when setting the seal part of the lip part on the opposite side to the deformed lip part so as to be positioned farther from the backup part side, balance the force between the inner and outer lip parts. The seating of the sealing device itself becomes more stable.

(Example) The illustrated example is an application example to a conventional type tandem master cylinder. The sealing device of the present invention is used partially in the primary cup portion of the master cylinder. First, the overall internal structure of the master cylinder will be briefly described with reference to FIG.

The master cylinder 10 has a cylinder body 14 in which a cylinder hole 12 having a uniform inner diameter is formed. Front end 16 of cylinder body 14
Is closed, and the second piston return spring 182,
The second piston 202, the first piston return spring 181, and the first
The pistons 201 are sequentially arranged, and the first piston 2
A push rod (not shown) is arranged behind 01.

The first and second pistons 201, 202 arranged in this way
Flanges 201a, 201b at locations separated in the front-rear direction, respectively.
202a and 202b, and the lip seal member 2 is adjacent to them.
21,241; 222,242 are attached respectively. Each of these lip seal members is attached to the inner peripheral surface of the cylinder body 14 and each piston.
The space between the first piston 201 and the first piston 201 is formed in front of the second piston 202, and the main pressure chamber 28 is formed in front of the first piston 201. Now, when the first piston 201 is pushed through the push rod (not shown), the first piston 201
The lip seal member 221 as the primary cup closes the relief port 301 communicating with the reservoir and generates pressure in the rear main pressure chamber 28. Then, the second piston 202 moves due to the pressure of the main pressure chamber 28, and similarly, the lip seal member 222 which is the primary cup of the second piston 202.
Closes the relief port 302 leading to the reservoir, and pressure is generated in the front pressure chamber 26. Main pressure chamber 28 and pressure chamber
Each pressure generated in 26 is transmitted to each wheel cylinder on the rear side and the front side through a pipe (not shown) for braking.

Here, among the lip seal members attached to the pistons, the ones denoted by reference numerals 241 and 242 only have a problem with the sealability, whereas the lip seal members denoted by reference numerals 221 and 222 (that is, the primary cup) have a sealability. Therefore, the liquid replenishment property also becomes a problem. Liquid replenishment is from the reservoir side to the main pressure chamber 28
And liquid supply to the pressure chamber 26, and the liquid on the reservoir side passes through the passages 321 and 322 lined up with the relief ports 301 and 302 and deforms the outer lip portions of the lip seal members 221 and 222 to flow.

FIG. 1 is an enlarged sectional view showing an embodiment of the primary cup used in the present invention.

The primary cups 221 and 222 made of a rubber molded product have a link shape as a whole, and are constituted by inner and outer lip parts 52 and 54 and a base part 50 connecting them.
For convenience of explanation, a point O located at a boundary between the inner lip portion 52 and the base portion 50 is set as an origin, a direction along the axis of the cylinder body 14 is defined as an X axis, and a direction orthogonal thereto is defined as a Y axis.

Normally, the front and rear surfaces of the base portion of the lip seal member are parallel to each other, but the rear surface 50b of the base portion 50 here is parallel to the Y axis, while the front surface 50a thereof has an angle θ with respect to the Y axis. It is inclined. Therefore, the base portion 50 gradually becomes thinner from the point O on the inner peripheral side to the point E on the outer peripheral side. The X coordinate of the point E is preferably set slightly larger than the X coordinate of the point P by, for example, about 0.2 mm. This is because the waist strength of the base portion 50 can be effectively reduced due to the relationship with the outer lip portion 54. However, the point P is the intersection of the line 1 defining the inner wall of the cylinder body 14 and the outer peripheral wall of the outer lip portion 54.

On the other hand, the inner and outer lip portions 52, 54 have the portions closest to the front surfaces 52a, 54a most protruding inward or outward. The outer lip portion 54 is entirely inclined at an angle α of about 30 ° with respect to the X axis, and a small ring-shaped surface 54c parallel to the X axis is formed on the outer peripheral wall portion adjacent to the front surface 54a. ing.
The outer lip portion 54 that elastically contacts the inner wall of the cylinder body 14 has a sealing portion between the point P and the point R.
The surface 54c having the point R as one starting point forms an oil film space having a wedge-shaped cross section with the inner wall of the cylinder body 14. Needless to say, this oil film space is effective in smoothing the relative movement between the primary cup and the cylinder body 14. Further, the inner lip portion 52 is only slightly inclined with respect to the X axis, and the beginning of the inclination is the rear surface 50.
It is not the point S on the b side but the point T that intersects the Y axis.
That is, in the period from the point S to the point T, the inner peripheral surface 52d of the inner lip portion 52 is parallel to the X axis. Therefore, although the whole is fitted to the piston 201, 202 side with an appropriate tightening margin, the actual seal portion is located in front of the point T and between the point U.

By the way, if you press the brake pedal twice,
In the primary cups 221, 222, the outer lip portion 54 is tilted forward, and the flange portion 201 of the piston as the backup portion is
The liquid will be replenished from the side of a, 202a. At the time of replenishing the liquid, the outer lip portions 54 of the primary cups 221 and 222 are deformed together with the base portion 50, so that the liquid replenishment property is very good. Moreover, when the inner lip portion 52 is formed to be thicker than the base portion 50 and the outer lip portion 54 as in the embodiment, even if the base portion 50 is deformed, the cup is seated stably, It is possible to secure effective sealing properties and liquid replenishment properties over a period of time. However, the sitting of the cup can be stabilized by setting the tightening margin of the inner lip portion 52 appropriately.

In addition to the clearance around the flanges 201a, 202a of the piston, the flange 2
Of course, it is also possible to use the holes provided through 01a and 202a. When using holes, flanges 201a, 2
It is preferable to mount a cup protector on the front surface of 02a so as to prevent the cup from being bitten by the hole and promote the deformation of the cup toward the front.

Further, in the plunger type master cylinder and the like, the liquid is replenished by the deformation of the inner lip portion, but the present invention can be applied to such a type.

(Effects of the Invention) According to the present invention, the base portion 50 of the lip seal member in the sealing device is formed so as to be gradually thinned toward the riff portion 54 which is deformed at the time of replenishing the liquid, and the lip which deforms with the base portion is formed. Since we have identified the relationship with the department,
The liquid replenishment property can be effectively improved, and the conventional liquid replenishment groove can be eliminated. Therefore, the length of the lip portion 54 that is deformed when replenishing the liquid can be shortened, and in particular,
In the master cylinder, remarkable effects of preventing port erosion and shortening the cylinder length can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view of a primary cup for explaining an embodiment of the present invention, and FIG. 2 is a sectional view showing an overall structure of a master cylinder to which the present invention is applied. 221,222 …… Lip seal member (primary cup), 5
0 …… Base part, 52 …… Inner lip part, 54 …… Outer lip part.

Claims (2)

[Claims] 1. A pair of lip portions, which are parallel to each other along an axis but are in relative motion with each other, are in contact with one wall surface, and the other lip portion is in elastic contact with the other wall surface. And a lip seal member having a base portion that connects both lip portions to each other, and at the same time, one of the lip portions is deformed from the side of the backup portion that supports the base portion to allow fluid movement. In the device, the base portion is formed so as to be gradually thinned toward a lip portion that deforms when the fluid moves, and is located at a boundary portion between the deforming lip portion and the base portion. (E) is a sealing device set so as to be closer to the backup unit side in the direction of the axis line as compared with the intersection (P) of the deformed lip portion and the wall surface on which the lip portion elastically contacts. 2. The backup portion side when the lip portion on the side opposite to the deformed lip portion is bisected in the direction of the axis line with a boundary point (O) between the lip portion and the base portion as a boundary. The sealing device according to claim 1, wherein the sealing device is in contact with the wall surface more strongly on the side farther from the side closer to.