JPH09177987A - Bearing-cum-combination seal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the reduction of the close sealing property even in a high pressure condition, by providing a circular groove on the contact surface side, in the combining seal of a cylindrical ring and an elastic ring. SOLUTION: At a piston part or a rod part 30 where a bearing-cum- combination seal can be reciprocated, two grooves 32 and 36 whose groove bottom surfaces are parallel to a sliding surface, and the depthes are different are provided. And an elastic ring 34 of a synthetic rubber or the like is installed to the deeper groove 32 at the grove bottom, while a synthetic resin sheet cylindrical ring 38 with a circular V-groove 40 with the length same as the length of the groove is installed to the shallower grove 36, and they are combined to make a bearing-cum-seal. In this case, the circular V-groove 40 is provided at the position corresponding around the border with the groove 32, when it is installed to the groove 36. Consequently, the force to press the cylindrical ring 38 is the diameter direction is concentrated at the part to the contacting side to the elastic ring 34 provided at the rear side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reciprocating rod / piston combination seal, and more particularly to a bearing / combined seal combination for a fluid pressure cylinder having improved sealing performance, reduced friction and improved mountability.

[0002]

2. Description of the Related Art FIG. 1 is a schematic view showing a state in which a conventional combined bearing / sealant seal is mounted on a piston rod. The piston 12 and the piston rod 14 assembled in a cylinder 10 are individually attached to each other. Combination seal for both bearings
16 and 18 are installed respectively. In particular, such combination seals are often used in pneumatic cylinders used in vehicle brake devices and the like.

As a conventional general technique, FIG.
The seal and bearing as shown in (b) were installed in separate grooves. FIG. 2 is a cross-sectional view of the piston 12, in which the conventional bearing / combined seal 16 provided therein is
A cylindrical ring 20 made of a synthetic resin thin plate that is mounted in the first groove 19 on the piston surface, and an elastic ring 22 that is mounted in the second groove 21 and supports the cylindrical ring 20 from behind. There is.

By the way, in recent years, there has been a demand for downsizing and improvement of control characteristics, and accordingly, even in the air cylinder as described above, a bearing which simultaneously satisfies the originally contradictory characteristics of high pressure and low friction coefficient. There is an increasing demand for dual-purpose combination seals. However, the conventional ones have drawbacks such as inferior sealing performance, and more leakage at higher pressures, and such requirements cannot be completely satisfied.

[0005]

SUMMARY OF THE INVENTION It is, therefore, an object of the present invention to provide a bearing / combined seal capable of eliminating deterioration of hermeticity even at high pressure.

[0006]

SUMMARY OF THE INVENTION The present invention is a combined seal of a cylindrical ring and an elastic ring, characterized in that an annular groove is provided on the contact surface side of the cylindrical ring, which also serves as a bearing. It is a combination seal.

[0007]

FIG. 3 is a partial cross-sectional view of a bearing / combined seal according to the present invention. In the reciprocating piston part or rod part, the groove bottom surface is parallel to the sliding surface and the depth is different. Providing a stepped groove.

Among the grooves provided in the piston portion or rod portion 30, an elastic ring 34 made of synthetic rubber or the like is mounted in the second step groove 32 having a deep groove bottom, while the first step groove 36 is provided with the first step groove 36. A thin plate cylindrical ring 38 made of synthetic resin (eg, Teflon, nylon, Delrin, etc.) with an annular V groove 40 having a length approximately equal to the groove length is mounted, and these are combined to form a bearing and seal. .

The annular V-shaped groove 40 is a first-step groove 36 when the thin plate cylindrical ring 38 made of synthetic resin is attached to the first-step groove 36.
It is provided at a position corresponding to the vicinity of the boundary between the second groove 32 and the second groove 32. The V-shaped groove 40 in the illustrated example may have a V-shaped cross section, a U-shaped semi-arcuate shape, a rectangular cross-section, or the like. FIG. 4 shows the contact surface pressure distribution, and FIGS. 4 (a) and 4 (b) are those of the prior art, and FIG.
(c) is the present invention.

In the conventional shape, since the cylindrical ring 20 has a simple rectangular cross section, the sliding surface of the cylindrical ring 20 comes into contact with the mating sliding surface due to the pressing force from the elastic ring 22. Therefore, the contact surface pressure distribution becomes as shown by the arrow in Fig. 4 (a), the sealing performance is poor, and the frictional force is large. However, as shown in FIG. 4B, when the bearing portion 42 and the seal portion 44 are separated, the contact pressure is low as a whole because the seal portion 44 is uniformly pressed by the elastic ring 22.

On the other hand, in the combination seal constructed according to the present invention, as shown in FIGS. 3 and 4 (c), the sliding surface of the cylindrical ring 38 is provided with an annular V groove 40,
Since the force that pushes the cylindrical ring by the back ring in the radial direction concentrates on the portion on the side in contact with the elastic ring 34 provided behind, the contact surface pressure distribution has its peak as shown by the arrow in FIG. 4 (c). , V-grooves can be made higher than when not provided.

FIG. 5 is a partially enlarged detailed view of the groove portion 50 provided in the cylindrical ring 36. The depth of the groove portion 50 is represented by b in the case of the V groove 40 and by c in the case of the concave groove 52 as shown by the dotted line, which functionally divides the bearing portion and the seal portion of the tubular ring 36. From the both sides of the strength function, it is preferably 2/3 or less of the wall thickness (t) of the cylindrical ring 36, and the width a of the groove 50 is preferably equal to or less than the depth.

As described above, by adopting the structure according to the present invention, the sealing performance is improved and the friction is reduced as compared with the conventional product. Since the seal portion of the cylindrical ring is expanded from the groove portion toward the end portion, the surface pressure of the end portion is increased and the sealing property is improved. Therefore, the seal according to the present invention is particularly effective for a pneumatic single-acting cylinder.

In the bearing-combined seal according to the present invention, the bearing portion does not receive the force of the elastic ring, so that the bearing can fully exert its function as a bearing. Moreover, since the cylindrical ring is deformed in the groove portion when mounted, it can be mounted more easily than the conventional shape.

[0015]

EXAMPLE In order to further clarify the function and effect of the present invention, a conventional product having no V groove as shown in FIG. 4 (a) and a split type device shown in FIG. 4 (b). Then, the combination seal according to the present invention shown in FIGS. 3 and 4 (c) was used in a pneumatic cylinder for a vehicle brake under the same conditions, and its characteristics were relatively evaluated. The results are summarized in Table 1. In addition, the evaluations were all performed in four stages, and the results of defectiveness to goodness were evaluated in four stages by x, Δ, ◯ and ⊚, respectively.

[0016]

[Table 1]

[0017]

As described in detail above, according to the present invention,
Since the contact surface of the integrally formed cylindrical ring is functionally divided into the seal surface and the bearing surface by the groove portion, the following excellent effects can be obtained.

Since the pressing force of the buckling acts intensively, the sealing performance is improved as a whole. Despite the improved sealability, the contact surface pressure decreased as a whole, resulting in less friction.

Providing the groove on the contact surface increases the flexibility of the cylindrical ring and facilitates mounting. The groove has the function of collecting lubricant, which reduces friction and eliminates abnormal wear due to lubrication failure.

Unnecessary surface pressure is not applied to the bearing portion, and the function as a bearing is enhanced. Such remarkable action and effect seen in the bearing-combined seal according to the present invention is particularly large in the pneumatic cylinder.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory diagram of a piston rod incorporating a combined seal that also serves as a bearing.

FIG. 2 is an explanatory view of a usage state of a bearing / combined seal according to a conventional technique.

FIG. 3 is a sectional view of a bearing / combined seal according to the present invention.

4 (a) and 4 (b) are contact surface pressure distribution diagrams of a bearing / combined seal according to the related art, and FIG.
FIG. 4 is a contact surface pressure distribution chart of the bearing-combined seal according to the present invention.

FIG. 5 is an explanatory view of the shape of the groove portion of the bearing-combined seal according to the present invention.

Claims (1)

[Claims] 1. A combined seal of a cylindrical ring and an elastic ring, characterized in that an annular groove is provided on the contact surface side of the cylindrical ring, which also serves as a bearing.