JP2015137652A - Buffer ring - Google Patents

Abstract

The present invention provides a buffering capable of suppressing a buckling of a body part.
An annular body part, an inner peripheral lip extending from an inner peripheral side end of the body part toward the fluid to be sealed, and an outer peripheral side end of the body part from the fluid to be sealed side and outer periphery. In a buffer ring 10 including an outer peripheral lip 13 extending so as to incline toward the side, the fluid pressure extends from the center of the body portion 11 toward the sealing target fluid side and is opposite to the sealing target fluid side. Is provided with an annular protrusion 14 provided so as to be able to come into contact with the side wall surface of the annular groove in a state where is higher than the fluid pressure on the fluid side to be sealed.
[Selection] Figure 3

Description

  The present invention relates to buffering for buffering the pressure of a fluid to be sealed.

  Conventionally, in a hydraulic cylinder or the like provided in various industrial machines (for example, construction machines), a sealing system in which a plurality of seals are combined is used. In such a sealing system, a packing (for example, U packing) that seals an annular gap between a piston rod (shaft) and a cylinder (housing) and a fluid to be sealed with respect to the packing are disposed and sealed against the packing. What is provided with the buffering which buffers the pressure of object fluid is known.

  The buffering according to the conventional example will be described with reference to FIG. FIG. 5 is a schematic cross-sectional view showing a mounting state of the buffer ring according to the conventional example. As shown, the buffer ring 200 is mounted in an annular groove 131 provided on the inner periphery of the shaft hole of the cylinder 130. The buffer ring 200 includes an annular body portion 210, an inner peripheral lip 220 that is slidable with respect to the piston rod 110, and an outer peripheral lip 230 that is in close contact with the groove bottom surface 131 a of the annular groove 131. .

  The buffer ring 200 configured as described above receives the fluid pressure (hydraulic pressure) on the fluid to be sealed O side and buffers the pressure, whereby a packing (not shown) provided on the atmosphere side A with respect to the buffer ring 200 Durability can be improved.

  Here, in the normal state, the fluid pressure on the fluid to be sealed O side is higher than the fluid pressure on the atmosphere side A, and the body portion 210 in the buffer ring 200 is against the side wall surface 131 b on the atmosphere side A of the annular groove 131. Are in close contact. However, since the packing is provided on the atmosphere side A with respect to the buffering 200 as described above, the fluid is contained in the sealed region between the buffering 200 and the packing. As the amount of contained fluid increases, the pressure in the sealed area increases. Thereby, the fluid pressure on the atmosphere side A (hereinafter referred to as “back pressure”) with respect to the buffer ring 200 may be higher than the fluid pressure on the fluid side O to be sealed. Therefore, in general, the buffering 200 is configured to be able to release such back pressure.

  Specifically, by making the rigidity of the outer peripheral lip 230 lower than the rigidity of the inner peripheral lip 220, when the back pressure increases, the outer peripheral lip 230 bends toward the inner peripheral side, and from the groove bottom surface 131 a of the annular groove 131. At a distance, the fluid returns to the sealed fluid side O. Further, a plurality of grooves 220 a are provided at the tip of the inner peripheral lip 220 on the sealing target fluid side O, and the inner peripheral lip 220 is in close contact with the side wall surface 131 c of the annular groove 131 on the sealing target fluid side O. Also, the flow path is secured.

  Here, when the groove width of the annular groove 131 is W and the distance from the outer peripheral surface of the piston rod 110 to the groove bottom surface of the annular groove 131 is L, it is generally set so that W ÷ L ≧ 1. The However, due to restrictions in the design of the hydraulic cylinder, W ÷ L may be forced to be less than 1. For example, when W ÷ L is 0.5 or less, the length of the body portion 210 (the length in the radial direction) is considerably larger than the thickness of the body portion 210 (the length in the axial direction). It will be long. Therefore, when the back pressure increases, the body portion 210 buckles before the outer peripheral lip 230 bends. FIG. 6 shows a state where the back pressure is increased and the body portion 210 is buckled. In the figure, the part indicated by X is a buckled part.

  Thus, when buckling occurs in the body part 210, the outer peripheral lip 230 and the body part 210 are brought into close contact with the side wall surface 131c on the fluid side O to be sealed in the annular groove 131, and the path for releasing the back pressure is blocked. End up. As a result, the back pressure leak function is not exhibited.

  In order to prevent buckling of the body portion 210, the length of the body portion 210 is shortened by increasing the thickness of the inner peripheral lip 220 or increasing the thickness of the outer peripheral lip 230. Can also be considered. However, in the former case, there is a problem that the contact pressure of the inner peripheral lip 220 with respect to the piston rod 110 becomes high and wears easily. In the latter case, the outer peripheral lip 230 becomes difficult to bend and it is difficult to release the back pressure. It can also be considered that W ÷ L is reduced by reducing L. However, in this case, since the buffering itself is small, the durability is adversely affected. As described above, any of the methods causes other problems.

JP 2005-337440 A

  The objective of this invention is providing the buffering which can suppress that a trunk | drum part will buckle.

  The present invention employs the following means in order to solve the above problems.

The buffering of the present invention
A fluid to be sealed against the packing is attached to an annular groove provided on the inner periphery of the housing on the side of the fluid to be sealed with respect to the packing that seals the annular gap between the shaft that reciprocally moves relative to the housing. Buffering to buffer the pressure of
An annular body portion that is in close contact with the side wall surface of the annular groove in a state in which the fluid pressure on the sealing target fluid side is higher than the fluid pressure on the side opposite to the sealing target fluid side;
The body portion extends from the inner peripheral side end portion toward the fluid to be sealed, and the inner peripheral end portion is provided slidably with respect to the outer peripheral surface of the shaft. An inner peripheral lip provided with a groove for securing a flow path even in contact with the side wall surface;
It extends so as to incline toward the sealing target fluid side and the outer peripheral side from the outer peripheral side end portion of the body portion, the outer peripheral side end portion is in close contact with the groove bottom surface of the annular groove, and is more rigid than the inner peripheral lip. An outer peripheral lip having a lower length in the axial direction (meaning the direction of the central axis of the shaft) than the inner peripheral lip;
In buffering comprising:
In the state where the fluid pressure on the side opposite to the sealing target fluid side is higher than the fluid pressure on the sealing target fluid side, the side wall surface of the annular groove extends from the central portion of the body portion toward the sealing target fluid side. Protrusions provided so as to be able to contact with each other are provided.

  According to the present invention, when the fluid pressure (back pressure) opposite to the fluid to be sealed with respect to the buffering is higher than the fluid pressure on the fluid to be sealed side, it is more rigid than the inner peripheral lip. Since the outer peripheral lip having a low height bends toward the inner peripheral side, the fluid can be released to the sealing target fluid side (back pressure is released). Further, since the flow path is secured even when the inner peripheral lip is in close contact with the side wall surface of the annular groove, the back pressure can be suitably released.

  And in the case of this invention, the protrusion extended toward the sealing object fluid side from the center part of the trunk | drum is provided. Therefore, even when the back pressure becomes high, it is possible to suppress the body portion from buckling due to the projections coming into contact with the side wall surface of the annular groove.

  The length of the protrusion in the axial direction may be designed to be the same as the length of the inner peripheral lip in the axial direction.

  As a result, when the back pressure is increased and the buffer ring is pushed toward the fluid to be sealed, the inner peripheral lip and the projection almost simultaneously abut against the side wall surface of the annular groove, so the buckling of the body portion is more reliably suppressed. can do.

  The protrusion is formed by an annular protrusion, and a groove for securing a flow path may be provided at the tip of the protrusion even in a state in contact with the side wall surface of the annular groove.

  Thereby, buckling of a trunk part can be controlled more certainly because a projection comprises an annular projection. Further, since the flow path is secured even if the tip of the annular protrusion is in close contact with the side wall surface of the annular groove, the back pressure can be suitably released.

  In addition, said each structure can be employ | adopted combining as much as possible.

  As described above, according to the present invention, it is possible to suppress the body portion from buckling.

FIG. 1 is a partially broken perspective view of a hydraulic cylinder. FIG. 2 is a schematic cross-sectional view of a sealing system according to an embodiment of the present invention. FIG. 3 is a schematic cross-sectional view of buffering according to an embodiment of the present invention. FIG. 4 is a schematic cross-sectional view showing a state at the time of back pressure leak in the buffering according to the embodiment of the present invention. FIG. 5 is a schematic cross-sectional view showing a mounting state of the buffer ring according to the conventional example. FIG. 6 is a schematic cross-sectional view showing a state in which the back pressure in the buffering according to the conventional example is increased.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be exemplarily described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention only to those unless otherwise specified. .

(Example)
The buffering according to the embodiment of the present invention will be described with reference to FIGS.

<Hydraulic cylinder>
With reference to FIG. 1, the structure of the whole hydraulic cylinder provided with a buffering, etc. are demonstrated. FIG. 1 is a partially broken perspective view of a hydraulic cylinder.

The hydraulic cylinder 100 includes a piston rod 110 as a shaft to which a piston 120 is fixed, and a cylinder 130 as a housing. The piston rod 110 and the cylinder 130 are configured to reciprocate relatively. More specifically, the piston 120 and the piston rod are controlled by controlling the oil pressure through two ports 134 and 135 provided in the cylinder 130 (controlling the oil pressure in the direction of arrow P in the figure). 110 can be reciprocated relative to the cylinder 130. In the following description, “axial direction” means the direction of the central axis of the piston rod 110.

  The hydraulic cylinder 100 includes a first sealing system S10 that seals an annular gap between the piston rod 110 and the cylinder 130, and a second sealing system S20 that seals an annular gap between the piston 120 and the cylinder 130. And are provided. The first sealing system S10 seals between the inside and the outside of the hydraulic cylinder 100, and the second sealing system S20 separates two sealed regions inside the hydraulic cylinder 100.

  The first sealing system S10 mainly suppresses (prevents) leakage of the buffer portion S11 that mainly buffers the fluid pressure (here, hydraulic pressure) and the fluid to be sealed (here, oil) mainly inside the hydraulic cylinder 100 to the outside. The main seal portion S12 is configured to include a dust seal portion S13 that mainly suppresses (prevents) dust intrusion.

<First sealing system>
In particular, the first sealing system S10 will be described in more detail with reference to FIG. FIG. 2 is a schematic cross-sectional view of a sealing system according to an embodiment of the present invention. In the inner periphery of the shaft hole of the cylinder 130, a first annular groove 131, a second annular groove 132 provided on the atmosphere side A with respect to the first annular groove 131, and an annular notch 133 provided on the atmosphere side A further. Is provided. A buffer portion S11 is provided in the first annular groove 131, a main seal portion S12 is provided in the second annular groove 132, and a dust seal portion S13 is provided in the annular notch 133.

  The buffer unit S11 is configured by a buffer ring 10.

  The main seal portion S12 includes a packing 30 having an inner peripheral lip 31 and an outer peripheral lip 32, and a backup ring 40. In this embodiment, a U-packing made of a rubber-like elastic body having a U-shaped cross section is adopted as the packing 30. A resin backup ring 40 is provided on the atmosphere side A of the packing 30. Thereby, it is suppressed that the inner peripheral edge of the packing 30 protrudes into a minute annular gap between the piston rod 110 and the cylinder 130.

  The dust seal portion S <b> 13 is configured by a dust seal 50 including a metal ring 51 and a rubber-like elastic seal portion 52 integrally formed with the metal ring 51. The seal portion 52 has an oil lip 52a and a dust lip 52b.

  With the configuration as described above, the buffer ring 10 is disposed closer to the sealing target fluid side O than the packing 30, so that the fluid pressure (hydraulic pressure) with respect to the packing 30 can be buffered. Further, by disposing the dust seal 50 on the atmosphere side A with respect to the packing 30, it is possible to prevent foreign matters (dust, dust, etc.) from entering the packing 30 side from the outside. From the above, the durability of the packing 30 can be improved.

<Buffering>
In particular, the buffering 10 according to the present embodiment will be described in more detail with reference to FIGS. FIG. 3 is a schematic cross-sectional view of the buffer ring 10 according to the embodiment of the present invention. FIG. 4 is a schematic cross-sectional view showing a state at the time of back pressure leak in the buffering according to the embodiment of the present invention.

  The buffering 10 according to the present embodiment is made of a rubber-like elastic body such as urethane rubber or NBR. The buffering 10 includes an annular body part 11, an inner peripheral lip 12 extending from the inner peripheral side end of the body part 11 toward the sealing target fluid side O, and an outer peripheral side end of the body part 11 to be sealed. A fluid side O and an outer peripheral lip 13 extending so as to incline toward the outer peripheral side are integrally provided. Further, the buffer ring 10 is also integrally provided with an annular protrusion 14 extending from the central portion of the body portion 11 toward the fluid to be sealed O side.

  The body 11 has a side wall surface on the atmosphere side A of the first annular groove 131 in a state where the fluid pressure on the fluid side O to be sealed is higher than the fluid pressure on the atmosphere side A (opposite side to the fluid side O to be sealed). Close contact with 131b.

  The inner peripheral lip 12 extends from the inner peripheral side end of the body portion 11 toward the sealed fluid side O, and the inner peripheral end thereof is slidable with respect to the outer peripheral surface of the piston rod 110. Composed. In addition, a groove 12 a that ensures a flow path is provided at the tip of the inner fluid lip 12 on the inner peripheral lip 12 even when the inner peripheral lip 12 is in contact with the side wall surface 131 c on the first fluid groove O in the first annular groove 131. Is provided. The grooves 12a are provided at a plurality of locations (for example, four locations) at equal intervals in the circumferential direction.

  The outer peripheral lip 13 extends from the outer peripheral side end of the body portion 11 so as to incline toward the sealing target fluid side O and the outer peripheral side, and the outer peripheral end closely contacts the groove bottom surface 131 a of the first annular groove 131. Configured as follows. The outer peripheral lip 13 is configured to be thinner and less rigid than the inner peripheral lip 12, and is configured to be shorter in the axial direction than the inner peripheral lip 12.

  The annular protrusion 14 can contact the side wall surface 131c of the sealing target fluid side O of the first annular groove 131 in a state where the fluid pressure on the atmosphere side A is higher than the fluid pressure on the sealing target fluid side O. Is provided. In this embodiment, the length of the annular protrusion 14 in the axial direction is designed to be the same as the length of the inner peripheral lip 12 in the axial direction. And the groove | channel 14a which ensures a flow path is provided in the state which contact | connected the side wall surface 131c of the 1st annular groove 131 at the front-end | tip of this annular protrusion 14. FIG. The grooves 14a are provided at a plurality of locations (for example, 4 locations) at equal intervals in the circumferential direction.

<Buffing behavior during back pressure leak>
In particular, the behavior of the buffer ring 10 at the time of back pressure leak will be described with reference to FIG. In the normal state, the fluid pressure on the fluid side O to be sealed is higher than the fluid pressure on the atmosphere side A, and the body portion 11 of the buffer ring 10 is the side wall surface on the atmosphere side A of the first annular groove 131 as described above. It is in close contact with 131b. Further, the inner peripheral end of the inner peripheral lip 12 contacts the outer peripheral surface of the piston rod 110 in a slidable state, and the outer peripheral end of the outer peripheral lip 13 is the groove of the first annular groove 131. It is in close contact with the bottom surface 131a. Thereby, the fluid pressure with respect to the packing 30 can be buffered.

  However, as described in the background art, as the amount of fluid confined in the sealed region between the buffer ring 10 and the packing 30 increases, the pressure in the sealed region increases. For this reason, the fluid pressure (back pressure) on the atmosphere side A relative to the buffer ring 10 may be higher than the fluid pressure on the fluid side O to be sealed. Note that the pressure in the sealed region increases as the sealing target fluid gradually leaks from the buffer ring 10 side to the packing 30 side due to the relative reciprocation of the piston rod 110 and the cylinder 130.

When the back pressure increases, the buffer ring 10 moves to the sealing target fluid side O. Then, the inner peripheral lip 12 and the annular protrusion 14 in the buffer ring 10 are in close contact with the side wall surface 131 c of the first annular groove 131 on the fluid side O to be sealed.

  When the back pressure further increases, the outer peripheral lip 13 bends toward the inner peripheral side and moves away from the groove bottom surface 131 a of the first annular groove 131. Accordingly, in a state where the back pressure is high, the fluid passes between the buffer ring 10 and the side wall surface 131b, passes between the outer peripheral lip 13 bent toward the inner peripheral side, and the groove bottom surface 131a. It returns to the fluid O to be sealed through the groove 14a and the groove 12a of the inner peripheral lip 12 (see arrow R in the figure). In this way, the back pressure can be released.

<Excellent points of buffering according to this embodiment>
According to the buffer ring 10 according to the present embodiment, when the back pressure becomes high, the outer peripheral lip 13 having a lower rigidity than the inner peripheral lip 12 bends toward the inner peripheral side, so that the fluid is sealed. The fluid side O can be released (back pressure is released). Further, even if the inner peripheral lip 12 is in close contact with the side wall surface 131c of the first annular groove 131, the flow path is secured by the groove 12a, so that the back pressure can be suitably released.

  And in the case of a present Example, the annular protrusion 14 extended toward the sealing object fluid side O from the center part of the trunk | drum 11 is provided. Therefore, even when the back pressure becomes high, it is possible to prevent the body portion 11 from buckling due to the annular protrusion 14 coming into contact with the side wall surface 131c of the first annular groove 131. Thereby, it can suppress that the path | route which releases a back pressure from being blocked | caused by the buckling of the trunk | drum 11 is blocked.

  The length of the annular protrusion 14 in the axial direction is designed to be the same as the length of the inner peripheral lip 12 in the axial direction. Therefore, when the back pressure is increased and the buffer ring 10 is pushed toward the fluid to be sealed O, the inner peripheral lip 12 and the annular protrusion 14 abut against the side wall surface 131c of the first annular groove 131 almost simultaneously. Accordingly, the buckling of the body portion 11 can be more reliably suppressed. Furthermore, in this embodiment, even if the tip of the annular protrusion 14 is in close contact with the side wall surface 131c of the first annular groove 131, the flow path is secured by the groove 14a, so that the back pressure can be suitably released.

  And according to the buffering 10 which concerns on a present Example, even if the length of the trunk | drum 11 is long compared with the thickness of the trunk | drum 11, the annular protrusion 14 suppresses buckling of the trunk | drum 11. Can do. Thereby, the wall thickness of the inner peripheral lip 12 or the outer peripheral lip 13 can be set to a thickness at which these functions are sufficiently exhibited.

(Other)
Regarding the width (the length in the radial direction) of the annular protrusion 14 described above, if the width is too wide, the rigidity becomes high, and the back pressure leakage performance may be reduced or wear may be promoted. If the width is too narrow, the annular protrusion 14 itself may be buckled. Therefore, the width of the annular protrusion 14 may be designed so that the rigidity of the annular protrusion 14 does not become excessively high and the annular protrusion 14 does not buckle.

  In the above embodiment, the case where the length of the annular protrusion 14 in the axial direction is designed to be the same as the length of the inner peripheral lip 12 in the axial direction is shown. However, if the buckling of the body portion 11 can be suppressed to prevent the path for releasing the back pressure from being blocked, the axial length of the annular protrusion 14 and the axial direction of the inner peripheral lip 12 can be reduced. The lengths do not necessarily have to be the same.

In the said Example, the case where the protrusion for suppressing the buckling of the trunk | drum 11 was comprised by the annular protrusion 14 was shown. However, the protrusion may be provided with a plurality of independent protrusions that are not annular and spaced in the circumferential direction. In this case, a gap is formed between the protrusions, and a flow path for releasing the back pressure is secured, so that the groove 14a is unnecessary.

DESCRIPTION OF SYMBOLS 10 Buffering 11 Body part 12 Inner peripheral lip 12a Groove 13 Outer peripheral lip 14 Annular protrusion 14a Groove 30 Packing 31 Inner peripheral lip 32 Outer peripheral lip 40 Backup ring 50 Dust seal 51 Metal ring 52 Seal part 52a Oil lip 52b Dustrip 100 Hydraulic cylinder 110 Piston rod 120 Piston 130 Cylinder 131 Annular groove 131a Groove bottom surface 131b Side wall surface 131c Side wall surface 132 Annular groove 133 Notch 134, 135 Port A Atmosphere side O Sealed fluid side S10 First sealing system S11 Buffer part S12 Main seal part S13 Dust seal part S20 Second sealing system

Claims (3)

A fluid to be sealed against the packing is attached to an annular groove provided on the inner periphery of the housing on the side of the fluid to be sealed with respect to the packing that seals the annular gap between the shaft that reciprocally moves relative to the housing. Buffering to buffer the pressure of
An annular body portion that is in close contact with the side wall surface of the annular groove in a state in which the fluid pressure on the sealing target fluid side is higher than the fluid pressure on the side opposite to the sealing target fluid side;
The body portion extends from the inner peripheral side end portion toward the fluid to be sealed, and the inner peripheral end portion is provided slidably with respect to the outer peripheral surface of the shaft. An inner peripheral lip provided with a groove for securing a flow path even in contact with the side wall surface;
It extends so as to incline toward the sealing target fluid side and the outer peripheral side from the outer peripheral side end portion of the body portion, the outer peripheral side end portion is in close contact with the groove bottom surface of the annular groove, and is more rigid than the inner peripheral lip. An outer peripheral lip having a lower length in the axial direction than the inner peripheral lip;
In buffering comprising:
In the state where the fluid pressure on the side opposite to the sealing target fluid side is higher than the fluid pressure on the sealing target fluid side, the side wall surface of the annular groove extends from the central portion of the body portion toward the sealing target fluid side. A buffering comprising a protrusion provided so as to be able to contact the buffering.   The buffering according to claim 1, wherein the length of the protrusion in the axial direction is designed to be the same as the length of the inner peripheral lip in the axial direction.   The said protrusion is comprised by the cyclic | annular protrusion, and the groove | channel which ensures a flow path is provided in the state which contact | connected the side wall surface of the said annular groove at the front-end | tip of Claim 1 or 2 characterized by the above-mentioned. Buffering.

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