JPH0736210Y2 - Reciprocating sealing mechanism - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a reciprocating sealing mechanism suitable for application to a hydraulic shock absorber used in a suspension mechanism that supports a vehicle body of an automobile or the like. The present invention relates to a reciprocating sealing mechanism in which sliding resistance is reduced while ensuring good performance.

<Prior Art> Generally, a so-called sealing mechanism is provided between a container containing a fluid and a shaft or the like provided so as to be able to reciprocate relatively so as to prevent the fluid in the container from leaking. In this case, it is desired that the seal mechanism prevent fluid leakage without hindering the reciprocating motion of the container and the shaft.

An example of such a conventional sealing mechanism, that is, a reciprocating sealing mechanism, is shown in FIG. 8 as being applied to a hydraulic shock absorber used in a suspension mechanism of an automobile or the like. In the figure, 1 is a hydraulic buffer, and a strut tube 2 of the hydraulic buffer 1 is provided with a reciprocating sealing mechanism 3 inscribed therein. The piston rod 4 of the hydraulic shock absorber 1 penetrates through the reciprocating sealing mechanism 3, and the piston rod 4 is formed on the seal lip 6 of the sealing material 5 by vulcanization molding provided in the reciprocating sealing mechanism 3. The slanted surface portion 7 having a conical surface is slidably supported and prevents leakage of a liquid (not shown) contained in the strut tube 2.

However, in such a reciprocating sealing mechanism, since the piston rod 4 is supported only by the seal lip 6 formed on the sealing material 5,
It is necessary to increase the contact pressure between the piston rod 4 and the seal lip 6 to ensure the sealing property. However, when the contact pressure is increased, the contact area between the piston rod 4 and the seal lip 6 is increased, so that the sliding resistance of the piston rod 4 with respect to the seal lip 6 is increased, and when it is applied to the suspension mechanism, the vehicle rides. There is a problem in that it is difficult to make the comfort comfortable.

Therefore, as a reciprocating sealing mechanism for preventing such a problem, there is one shown in FIG. (For example, Japanese Utility Model Laid-Open No. 62-93463).

Therefore, FIG. 9 will be described (note that the same components as those of the conventional example shown in FIG. 8 are designated by the same reference numerals and detailed description thereof will be omitted). In FIG. 9, the seal lip 13 of the seal material 12 formed by vulcanization molding provided in the reciprocating sealing mechanism 11 has an inclined surface portion 14 formed in a conical surface shape, and the inclined surface portion 14 has a plurality of annular grooves 15a. ~ 15d are formed.
Therefore, the contact area between the piston rod 4 and the seal lip 13 is reduced by the amount of the annular grooves 15a to 15d formed, and in this case, it is intended to avoid an increase in sliding resistance due to the increase in contact pressure. is doing.

<Problems to be solved by the invention> However, in this case, the sealing material 12 has an annular groove 15
Since a to 15d are formed, it is necessary to provide protrusions corresponding to the respective annular grooves 15a to 15d in the mold used for vulcanization molding of the sealing material 12, and furthermore, the protrusions are formed flat. Therefore, the cost of the mold is increased by forming the protruding portion, and the contact pressure between the seal lip 13 and the piston rod 4 whose top is flat due to the dimensions of the annular grooves 15a to 15d has an influence. Receiving the annular groove 15a ~ 1
Since it is necessary to increase the dimensional accuracy of 5d, the shape of the mold becomes complicated, and it is difficult to ensure sufficient dimensional accuracy during vulcanization molding, and there is a concern that sliding resistance may increase in some cases.

<Object of the Invention> Therefore, the present invention provides a plurality of annular projections on the conical inclined surface portion so that the contact pressure of the inclined surface portion is concentrated and dispersed to each annular projection, and the sealing performance of the inclined surface portion is improved. It is intended to reduce the sliding resistance while ensuring the above, and to reduce the die cost.

<Means for Solving the Problems> The reciprocating sealing mechanism according to the present invention achieves the above object.
A seal member provided between a container containing a fluid and a rod slidably penetrating one end of the container to seal a pair of the container penetrating, the seal member having a mountain-shaped cross section. In a reciprocating sealing mechanism in which a lip is formed so as to project radially inward, and a tip end portion and an inclined surface portion of the lip elastically contact the outer circumference of the rod to seal a sliding portion, the inclination of the lip It is characterized in that a plurality of annular protrusions having an arc-shaped cross section are provided on the surface portion, the heights from the inclined surface being substantially equal.

<Operation> In the present invention, the annular projections having an arcuate cross-section provided on the inclined surface of the lip concentrate and disperse the contact pressure on the sliding portion of the rod, respectively, and from the end portion side projected by the sliding portion. The contact pressure gradually decreases. Also, since the annular projection has an arcuate cross section, it is possible to obtain sufficient rigidity against sliding resistance in the axial direction, and to keep the pressure distribution on the contact surface of each annular projection on the rod constant regardless of the sliding direction. In addition, it is sufficient to form an annular groove corresponding to the annular protrusion in the die, which reduces the die cost.

<Example> Hereinafter, the present invention will be described with reference to the drawings.

1 to 7 are views showing an embodiment of a reciprocating sealing mechanism according to the present invention, in which the present invention is applied to a hydraulic shock absorber used in a vehicle suspension mechanism.

First, the configuration will be described.

In FIG. 1, 21 is a twin-tube type hydraulic buffer, and the hydraulic buffer 21 has an outer tube 22 and an inner tube 23. A first working chamber 24 is defined inside the inner tube 23, and a second working chamber 25 is defined outside the inner tube 23. Each working chamber
24 and 25 are filled with low viscosity oil,
And 25 can communicate with each other through a predetermined valve (not shown). A piston rod 26 connected to a piston (not shown) is inserted into the inner tube 23, and the piston rod 26 is supported by a rod guide 27 press-fitted into the end portion of the outer tube 22. A reciprocating sealing mechanism 28 is provided on the rod guide 27 coaxially with the rod guide 27, and the reciprocating sealing mechanism 28 is fixed to an end portion of the outer tube 22. The piston rod 26 is included in the reciprocating sealing mechanism 28.
Through which the reciprocating sealing mechanism 28 is a piston rod.
While allowing the smooth reciprocating motion of 26, the working chamber 25 is sealed to prevent the oil in the working chamber 25 from leaking to the outside.

As shown in FIG. 2, the reciprocating sealing mechanism 28 includes a seal member 31 formed by vulcanization, a seal reinforcing ring 32 for reinforcing the seal member 31, and a portion A of the seal member 31 in FIG.
It consists of a ring 33 that is in close contact with
The shape of the part is shown in FIG. That is, the seal member 31 has a first seal lip 41 and a second seal lip 42, and each seal lip 41, 42 has an inclined surface portion 43, 44 formed in a conical shape. Each inclined surface portion 43,
Protrusions (annular protrusions) 45a to 45e and 46a to 46d, which are continuously formed in an annular shape, are provided on the respective seal lips 44, 42.
Of the protrusions 45a to 45e and 46a to 46d are arranged in parallel with each other at a predetermined distance from the tip of each of the protrusions 45a to 45e and 46a to 46d. It is formed in an arc shape with respect to the axial center so as not to come into contact with the rod 26. Specifically, each protrusion 45a-45e and 46a-4
When the shapes of 6d are the same, as shown in FIG. 4 (a), if the cross-sectional shape of the protrusion 45n is an arc of radius R, the protrusion 4
If the height of 5n is h1 and the width is b2, the relationship of [b2 = 2 · h1] is established, and as shown in FIG. If the height of time is h2 and the width is b2, the relationship of [b2> 2 · h2] is established. That is, the shapes of the protrusions 45a to 45e and the protrusions 46a to 46d are determined so that the width thereof is twice or more the height thereof.

The bottom surface between the projections existing between the projections 45a to 45e and 46a to 46d is a flat surface in the sectional shape shown in FIG. In addition, each of the protrusions 45a to 45e and 46a to 46d has a protrusion shape in which the apex is arcuate with respect to the flat bottom face between the protrusions.

Next, the operation will be described.

FIG. 5 is a view showing the pressure distribution of the inclined surface portion 44 of the seal lip 42 with respect to the piston rod 26. Since the shapes of the inclined surface portion 44 and the inclined surface portion 43 are almost the same, only the inclined surface portion 44 is shown. .

In this case, the seal lip 42 has an inclined surface portion 44, and in order to form the protrusions 46a to 46d having an arc top at the inclined surface portion, the contact between the piston rod 26 and the seal lip 42 is the tip of the seal lip 42. The projections 46a to 46d, which have an arcuate portion and a peak, are limited to 5 locations, a total of 6 locations, and the contact pressure at the tip of the seal lip 42 is the highest.
The contact pressure decreases in the order of a to 46d. Moreover, the protrusions 46a-4
In 6d, since the peak is arcuate, the pressure distribution is highest at the center of the protrusion and sharply lower at both ends, so there is a peak at the center of the protrusion and the contact pressure It has a pressure distribution that narrows the high range.

Therefore, the closer to the tip of the seal lip 42, the larger the peak, the sealing function is performed, and the peak of this contact pressure can sufficiently secure the sealing performance of the reciprocating sealing mechanism 28.

Further, when the piston rod 26 slides, the range corresponding to the peak portion of high contact pressure is narrow, so the piston rod 26
Since the oil film on the surface of 26 is not cut, and in addition, oil reservoirs 49a to 49d are formed between the piston rod 26 and the seal lip 42, lubrication when the piston rod 26 slides is sufficiently performed. The sliding resistance can be made sufficiently small.

Incidentally, in the conventional example shown in FIG. 9, since a protrusion is formed on a flat portion in the cross-sectional shape forming the inclined surface 14 of the mold, and the annular grooves 15a to 15d are formed by this protrusion, the annular groove 15a is formed. The tops of the inter-groove projections existing between ˜15d are naturally flat in cross-sectional shape depending on the shape of the portion of the mold forming the inclined surface 14. Therefore, the pressure distribution of the projections between the annular grooves against the piston rod 4 is as shown in FIG.
A substantially constant pressure distribution having no peak is continuously generated in each annular groove projection. Therefore, the contact area of the seal lip 13 with respect to the piston rod 4 becomes large, and the oil film is apt to be cut, and in combination with the difficulty in obtaining the shape and size of the seal lip 13 which is a problem of the above-mentioned conventional technology, Ensuring of the sealing property will be insufficient.

On the other hand, in this embodiment, as shown in FIG. 3, since the protrusions 46a to 46d are formed by the annular grooves of the mold, the inter-projection bottom surfaces present in the protrusions 46a to 46d are flat in cross section. Although it becomes a surface, the tops of the protrusions 46a to 46d are arcuate. Therefore, as described above, the contact pressure between the piston rod 26 and the seal lip 42 is the highest at the tip of the seal lip 42, and the contact pressure is reduced in the order of the protrusions 46a to 46d. The contact pressure generated at 1 becomes P1max, and this P1max becomes the maximum value, which is larger than the maximum value P2max of the conventional example shown in FIG. This means that sufficient sealing performance is secured between the piston rod 26 and the seal lip 42, and the oil sump 49a
Together with the formation of ~ 49d, a sufficient lubrication effect can be obtained. Further, since the protrusions 46a to 46d are formed on the inclined surface portion of the seal lip 13 and have the shape of an arc having a radius R, the pressure distribution corresponding to each of the protrusions 46a to 46d can be smoothly changed. Therefore, it is possible to prevent the occurrence of sticking by preventing pulling and the like. In addition, the protrusion
By setting the shapes of 46a to 46d so that the width is at least twice as high as the height, each protrusion 46 when contacting the piston rod 26
The rigidity of the piston rod 26 in the axial direction can be enhanced by flattening the a to 46d, and the protrusions 46a to 46d can be prevented from collapsing and stable sealing performance can be exhibited.

Here, paying attention to the dynamic friction characteristics of the hydraulic shock absorber 21 at the time of slight vibration, as shown in FIG. 6, when a sinusoidal vibration wave is given as the displacement waveform, the hydraulic shock absorber 21 of the present embodiment.
Is less than half the friction as compared with the first conventional example, which means that the inclined surface portions 43, 44 between the piston rod 26 and the seal lips 41, 42 are sufficiently lubricated. Is shown.

As a result, the lubrication between the piston rod 26 and the seal lips 41, 42 is sufficiently performed, and the dynamic friction can be made sufficiently small, so that the riding comfort of the vehicle can be made good.

Also, when comparing the dynamic friction with respect to the piston speed, as shown in FIG. 7, this embodiment can obtain a sufficient friction reducing effect as compared with the first conventional example.

As described above, in this embodiment, by providing the protrusions 45 and the protrusions 46 on the seal lips 41 and 42, the sliding resistance is reduced while ensuring the sealing property,
The protrusions 45 and the protrusions 46 can be formed on the seal member 31 only by forming grooves corresponding to the protrusions 45 and the protrusions 46 in the mold used for the vulcanization molding of the seal portion 31. Therefore, it is easy to form a groove on the die, and the die cost can be reduced.

Moreover, in this embodiment, since the projections 45 and 46 have an arcuate cross section and are formed to have a width twice or more with respect to the height, sufficient rigidity against sliding resistance in the axial direction is obtained. Can each piston rod 26
The pressure distribution on the contact surface with respect to can be kept constant regardless of the sliding direction, and stable sealing performance can be exhibited also from this point.

In the present embodiment, the case where the reciprocating sealing mechanism is applied to the hydraulic shock absorber used in the vehicle suspension mechanism is shown, but the realization of the present invention is not limited to this.
The point is that the present invention can be applied as long as one container or the like is kept airtight while the other is slidably supported. For example, it can be applied to a seal mechanism between a piston and a cylinder.

(Effect) According to the present invention, there is provided a seal member which is provided between a container containing a fluid and a rod which slidably penetrates one end of the container and seals the penetrated one end of the container. The sealing member is formed such that a lip having a mountain-shaped cross section is formed so as to project inward in the radial direction, and a tip end portion and an inclined surface portion of the lip elastically contact the outer circumference of the rod to seal the sliding portion. Since a plurality of annular projections having an arcuate cross-section whose heights from the inclined surface are substantially equal to each other are provided on the inclined surface portion of the lip, it corresponds to the inclined surface portion of the seal member in the mold for manufacturing the seal member. It suffices to grind the portion to be cut to form the groove portion, so that not only the mold processing is easy, but also the cross-sectional shape can be easily formed into an arc shape.

Further, in the present invention, since the lip is an inclined surface and a plurality of annular projections having substantially the same height from the inclined surface are provided on the inclined surface, the contact pressure on the sliding portion of the rod is concentrated respectively. While being dispersed, the contact pressure will be gradually reduced from the end side protruding by the sliding part, and moreover,
Since the annular projection has an arcuate cross section, sufficient rigidity can be obtained against sliding resistance in the axial direction, and the pressure distribution on the contact surface of each of the multiple annular projections on the rod is kept constant regardless of the sliding direction. Therefore, the sliding resistance can be reduced while exhibiting stable sealing performance.

[Brief description of drawings]

FIG. 1 is a sectional view showing a main part of an embodiment in which a reciprocating sealing mechanism according to the present invention is applied to a hydraulic shock absorber, and FIG. 2 is a reciprocating sealing mechanism in the embodiment of the present invention shown in FIG. 3 is an enlarged sectional view showing the seal lip of the reciprocating sealing mechanism of FIG. 2, FIG. 4 is a sectional view showing the protrusion formation of the seal lip shown in FIG. 3, and FIG. Is a view for explaining the action of the seal lip shown in FIG. 3, FIG. 6 is a graph showing the dynamic friction characteristics with respect to the displacement of the seal lip, FIG. 7 is a graph showing the dynamic friction reducing effect, and FIG. FIG. 9 is a cross-sectional view of an essential part showing an example in which the reciprocating sealing mechanism is applied to a hydraulic shock absorber. FIG. 9 is a cross-sectional view of the essential part showing another example of the prior art, and FIG. It is a figure explaining the effect | action of the seal lip similar to FIG. 5 in an example. 23 ... Inner tube (container), 26 ... Piston rod (second member), 28 ... Reciprocating sealing mechanism, 31 ... Seal member, 41, 42 ... Seal lip, 43, 44 ... Inclined surface , 45, 46 ... Protrusion (annular protrusion).

Claims (2)

[Scope of utility model registration request] 1. A seal member which is provided between a container containing a fluid and a rod which slidably penetrates one end of the container and seals the penetrated one end of the container. In a reciprocating sealing mechanism, a lip having a mountain-shaped cross section is formed so as to project inward in the radial direction, and a tip portion and an inclined surface portion of the lip elastically contact the outer circumference of the rod to seal the sliding portion. The reciprocating sealing mechanism is characterized in that a plurality of annular projections having an arcuate cross section are provided on the inclined surface portion of the lip, the heights from the inclined surface being substantially equal. 2. The utility model registration claim 1, wherein the cross-sectional shape of the annular projection is formed in an arc shape having a substantially constant radius, and the width is formed to be twice or more the height. The reciprocating sealing mechanism according to the item.