JPH0516462Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to a seal, and particularly to a seal that is effective for use in a sliding portion of an actuator driven by fluid pressure.

[Background technology] The performance of gaskets used for the sliding parts of actuators driven by fluid pressure is stable under various conditions, and the resistance force during startup and sliding is low and stable. What you are doing is important.

Limiting the problem to the packing, these performances are determined by the material that makes up the packing, the shape and hardness of the packing, the surface condition, the tightness of the packing, and the like.

Conventionally, U
There are two types of seals, called "Putskin", which achieve sealing performance through the expansion force of fluid pressure applied to a recessed part of a U-shaped cross section, and ones that achieve sealing performance mainly through interference, such as O-rings. Squeeze-shaped packskin and the like are known.

However, for any of the above-mentioned packings, when usage conditions such as cylinder diameter, tightness, and applied fluid pressure differ, the optimal cross-sectional shape and dimensions corresponding to each condition can be determined using, for example, a finite element method. The disadvantage is that it is difficult to determine the performance based on various factors, and it is not easy to provide a product with optimal performance for various different usage conditions.

[Purpose of the invention] The purpose of the invention is to provide a packing that can have optimal performance for various different usage conditions by changing only some dimensions while keeping the cross-sectional shape the same. There is a particular thing.

Another object of the present invention is to provide a packing whose sealing characteristics can be easily optimized through structural analysis.

[Summary of the invention] The invention provides first and second parts that slide relative to each other.
is attached to a groove cut in one of the members, and contacts both the first and second members at the same time, thereby allowing fluid to flow between the first member and the second member. The blocking packing has both end surfaces in the axial direction forming planes perpendicular to the axial center, and sealing surfaces that contact the first and second members respectively are constituted by cylindrical surfaces perpendicular to the planes, and the sealing surfaces in the axial direction By forming a recess around the entire circumference at approximately the center of both end faces, the cross-sectional shape remains the same, but by only changing some dimensions, it can be optimized for a variety of different usage conditions. It is designed to have high performance.

[Embodiment 1] Fig. 1 is a sectional view of a packing that is an embodiment of the present invention, and Fig. 2 is a front view thereof.

The end surface 2 and the end surface 3 of the packing 1 are arranged in the axial direction,
That is, it is composed of a plane perpendicular to the left-right direction in the figure, and includes an inner wall surface 4 of a cylinder C (first member) and a piston P that slides inside the cylinder C.
A sealing surface 6 and a sealing surface 7 that respectively come into contact with the bottom surface 5 of the storage groove G carved in the outer circumference of the (second member) are constituted by cylindrical surfaces orthogonal to the end surfaces 2 and 3.

In this case, the ratio of the distance b between the sealing surfaces 6 and 7 in the natural state to the distance a between the end surfaces 2 and 3 is 2 or more.

A recess 8 and a recess 9 are formed on the end surfaces 2 and 3 over the entire circumference, respectively.

And in any cross section of Patsukin 1,
The recesses 8 and 9 have symmetrical cross-sectional shapes with respect to their center lines.

Furthermore, a plurality of slits 10 and 11 are cut in the end faces 2 and 3 in the radial direction.

Furthermore, end faces 2 and 3 and sealing faces 6 and 7
An inclined surface 12 is formed at the corner where the two intersect.

Thereby, by appropriately setting the inclination angle of the inclined surface 12, the desired value of the length dimension in the axial direction of the cylinder C and the piston P, that is, the contact area with respect to the cylinder C and the piston P, can be set on the sealing surface 6 and the sealing surface 7. In addition, when the packing 1 is subjected to compressive deformation in the radial direction during mounting, the deformation is absorbed in the region of the inclined surface 12 in combination with the recesses 8 and 9. As a result, the dimensions and shapes of the sealing surfaces 6 and 7 and the position of the sealing point S during operation as described later are stabilized.

Note that FIG. 1 shows the case where the seal 1 is in its natural state, and in the actual installed state, the dimension b is reduced by a predetermined value, and the sealing surfaces 6 and 7 are respectively attached to the cylinder C. It is brought into close contact with the inner wall surface 4 and the bottom surface 5 of the storage groove G of the piston P with a predetermined contact pressure.

The operation of this embodiment will be explained below.

FIG. 4 shows the results of analyzing the shape change between the natural state and the worn state of the packing 1 of this example using the finite element method, where the solid line and the broken line represent the natural state and the worn state, respectively. There is.

As shown in the figure, the packing 1 of this embodiment
In the above, the end face 2 and the end face 3 of the packing 1 are
is composed of a plane perpendicular to the axial direction, and the sealing surface 6 and the sealing surface 7 are connected to the end surfaces 2 and 3.
Furthermore, the end faces 2 and 3 are respectively carved with a recess 8 and a recess 9 over the entire circumference, and between the end faces 2 and 3 and the cylindrical face are grooves 8 and 9. , since the inclined surface 12 is provided, the dimensional change in the radial direction is absorbed at the portion where the cross section is reduced by the recesses 8 and 9,
The inner wall surface 4 of the cylinder C of the seal surfaces 6 and 7 and the housing groove G of the piston P have a relatively small overall shape change between the free state and the device state, and are important when calculating sliding resistance etc. For example, if the contact area with the bottom surface 5 of the end surface 2 does not change significantly, and the distance b between the seal surfaces 6 and 7 shown in FIG.
By setting the ratio to the distance a between the sealing surfaces 6 and the inner wall surface 4 of the cylinder C to be 2 or more, the contact pressure of the sealing surface 6 against the inner wall surface 4 of the cylinder C can be optimally maintained, and even if conditions such as the tightness of the packing 1 are variously changed, the sealing 1 It becomes possible to accurately calculate the sliding resistance between the sealing surface 6 of the cylinder C and the inner wall surface 4 of the cylinder C.

Furthermore, Fig. 5 shows the results of analysis using the finite element method of changes in the shape of the packing 1 when it is worn and under pressure (pressure is applied from the right side of the figure), and the solid and broken lines are , respectively, show before and after pressurization.

As shown in the figure, the fluid pressure applied to the right side of the piston P is transmitted through the slit 10 radially carved in the right end surface 2 of the packing 1 and the recess 8 on the right end surface 2 of the packing 1. The end surface 3 is acted on over the entire surface of the piston P and is further pressed against the left wall surface of the housing groove G of the piston P by the fluid pressure.
is composed of a plane perpendicular to the axial direction, so that the packing 1 is stably held on the side wall of the storage groove G, and the overall shape of the packing 1 is not changed.
In particular, the position and shape of the sealing point S formed at the contact area between the inner wall surface 4 of the cylinder C and the sealing surface 6 becomes stable, and the sealing performance of the packing 1 under pressure can be accurately grasped.

This is exactly the same when fluid pressure is applied to the left end surface 3 side of the packing 1.

Moreover, the so-called blow-by phenomenon caused by concentration of fluid pressure between the sealing surface 6 and the inner wall surface 4 of the cylinder C is prevented.

As a result of the above, it becomes possible to design and provide optimal sealing performance corresponding to the usage conditions of the packing 1 by, for example, the finite element method.

[Embodiment 2] FIG. 3 is a front view of a packing that is another embodiment of the present invention.

In the second embodiment, the shape of the packing 1a as viewed in the axial direction is an ellipse consisting of a pair of parallel straight lines and a semicircle, which is different from the first embodiment. Even with this ellipse shape, the same effects as in the first embodiment can be obtained, and it becomes possible to attach it to pistons of various shapes.

It goes without saying that the present invention is not limited to the above-described embodiments, and can be modified in various ways without departing from the spirit thereof.

For example, the shape of the recesses 8 and 9 carved in the circumferential direction of the end surfaces 2 and 3 is not limited to a square shape, but may be a semicircle or any other shape.

[Effects] (1) By being attached to a groove carved in one of the first and second members that slide relative to each other and simultaneously contacting both the first and second members, A packing that prevents fluid flow between the first member and the second member, both end faces in the axial direction form a plane perpendicular to the axial center, and the first
and a sealing surface that contacts the second member is composed of a cylindrical surface perpendicular to the plane, a recess is formed in the center of both end faces in the axial direction over the entire circumference, and the cross-sectional shape is symmetrical with respect to the recess. The ratio of the distance between the seal surfaces to the distance between both end surfaces is 2 or more, and a plurality of slits are carved in the radial direction of both end surfaces, and a plurality of slits are carved at the corners where both end surfaces and the seal surfaces intersect. Since the slanted surface is formed, it is possible to provide optimal performance for various different usage conditions by simply changing some of the dimensions while keeping the cross-sectional shape the same.

(2) By setting the ratio of the distance between the seal surfaces to the distance between the two end surfaces to be 2 or more, the contact pressure of the seal surfaces can be maintained optimally.

(3) With multiple slits carved in the radial direction on both end faces, fluid pressure is applied to the entire end face of the seal, preventing blow-by phenomena caused by fluid pressure concentrating on the sealing surface, etc. can.

(4) In any cross section of the packing 1, the recess 8
Since the recess 9 has a symmetrical cross-sectional shape with respect to the center line, the sealing characteristics can be easily optimized by structural analysis using a technique such as the finite element method.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of a packing which is an embodiment of the present invention, Fig. 2 is a front view thereof, Fig. 3 is a front view of a packing which is another embodiment of the invention, and Fig. 4 is a sectional view of the packing which is an embodiment of the present invention. Figure 5 shows the results of an analysis using the finite element method of the changes in shape of the invented packing between the natural state and the fitted state. It is a figure showing the result. 1, 1a...Packing, 2, 3...End face, 4...
...Inner wall surface, 5...Bottom surface, 6, 7...Seal surface,
8, 9... recess, 10, 11... slit, 12
... Inclined surface, C ... cylinder, P ... piston,
G: Storage groove, S: Seal point, a: Distance between end faces, b: Distance between seal surfaces.

Claims (1)

[Scope of utility model registration request] It is attached to a groove cut in one of the first and second members that are slidable relative to each other, and is connected to the first member by simultaneously contacting both the first and second members. A packing that prevents fluid flow between the first and second members, wherein both end faces in the axial direction form planes perpendicular to the axial center, and sealing surfaces that contact the first and second members, respectively, It is composed of a cylindrical surface perpendicular to a plane, a recess is formed around the entire circumference at approximately the center of both end surfaces in the axial direction, and the cross-sectional shape is symmetrical with respect to the recess,
The ratio of the distance between the sealing surfaces to the distance between the both end surfaces is 2 or more, and a plurality of slits are carved in the radial direction of the both end surfaces, and a plurality of slits are formed at the corners where the both end surfaces and the sealing surfaces intersect. A packkin characterized by having an inclined surface formed in the part.