JP2020008088A - Backup ring - Google Patents

Abstract

To provide a backup ring capable of sufficiently preventing a slide surface of a reciprocating shaft from being damaged even in a case where metal foreign matter mixed in oil enters between the backup ring and the reciprocating shaft.SOLUTION: A backup ring 1 supports an annular packing that is arranged in a housing and contacts with an outer peripheral surface 102a of a reciprocating shaft 102 whose tip side projects toward the atmosphere and base end side is positioned on a hydraulic side. On an inner peripheral surface 1a facing the outer peripheral surface 102a of the reciprocating shaft 102, a plurality of projections 6 are formed over the entire circumference along the axial direction of the reciprocating shaft 102. The length of the projection 6 is shorter than the overall length of the backup ring 1 in the axial direction.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a backup ring, and more particularly, to a backup ring that can sufficiently prevent a sliding surface of a reciprocating shaft from being damaged even if metal foreign matter mixed in oil enters between the reciprocating shaft. About.

  Conventionally, as shown in FIG. 6, a packing 100 used for a rod seal portion in a high pressure environment exceeding 30 MPa such as a hydraulic cylinder and a suspension of a construction machine and a shock absorber of an automobile is used for securing pressure resistance, for example. A buffer ring 300 is configured by using a backup ring 200 made of polyamide resin in combination (Patent Document 1). The buffering 300 performs a hydraulic buffer and a high-temperature oil cut under a high load.

  The reciprocating shaft 400 is disposed in a housing (not shown) filled with oil, and is capable of reciprocating in the axial direction as indicated by an arrow A in FIG. The reciprocating shaft 400 has a base end side (right side in FIG. 6) positioned inside the housing and a front end side (left side in FIG. 6) axially outside the open end of the housing (hereinafter referred to as “atmosphere side”). )).

  The packing 100 is integrally formed in a ring shape from a rubber-like elastic material such as urethane. The packing 100 seals oil in the housing with an oil lip 110. The packing 100 forms an appropriate oil film on the outer peripheral surface (sliding surface) 410 of the reciprocating shaft 400. The backup ring 200 is disposed and supported in an annular groove formed in the housing. The annular groove is formed so as to surround the outer peripheral surface 410 of the reciprocating shaft 400.

  When excessive pressure is applied, the packing 100 may deform and protrude into the annular gap between the reciprocating shaft 400 and the housing, and may be damaged. In the buffer ring 300 using the backup ring 200 together, the backup ring 200 is deformed by pressure and comes into close contact with the reciprocating shaft 400, so that the packing 100 is suppressed from protruding into the annular gap. As described above, the backup ring 200 maintains the shape of the packing 100 for a long period of time even in a high-pressure environment, and contributes to the improvement of the life of the hydraulic device.

JP-A-02-035272

  The backup ring 200 needs to have a hardness that does not protrude into the annular gap between the reciprocating shaft 400 and the housing. Therefore, when metal foreign matter mixed in oil enters between the backup ring 200 and the sliding surface 410 of the reciprocating shaft 400, a high contact pressure is generated between the metal foreign material and the reciprocating shaft 400. As shown in FIG. 7, the sliding surface 410 of the reciprocating shaft 400 may be scratched 411. If the sliding surface 410 is scratched 411, oil leakage may occur between the packing 100 and the reciprocating shaft 400.

  As shown in FIG. 6, some backup rings 200 are provided with a plurality of ridges 210 on the inner peripheral surface to reduce the contact area of the reciprocating shaft 400 with the sliding surface 410. By reducing the contact area with the sliding surface 410, metal foreign matter was less likely to stay between the backup ring 200 and the sliding surface 410, and an attempt was made to prevent the sliding surface 410 from being scratched 411. Things.

  However, in the backup ring 200 in which the plurality of ridges 210 are provided over the entire length L in the axial direction of the backup ring 200, it is not possible to sufficiently prevent stagnation of metal foreign matters, and it is still sufficient to prevent the sliding surface 410 from being damaged. Could not be prevented.

  Therefore, the present invention provides a backup ring that can sufficiently prevent the sliding surface of the reciprocating shaft from being damaged even if metal foreign matters mixed in oil enter between the reciprocating shaft. Make it an issue.

  Other objects of the present invention will become apparent from the following description.

  The above object is achieved by the following inventions.

1.
A backup ring that is disposed in the housing and supports an annular packing that is in contact with the outer peripheral surface of a reciprocating shaft whose distal end projects toward the atmosphere and whose proximal end is located on the hydraulic side,
On the inner peripheral surface facing the outer peripheral surface of the reciprocating shaft, a plurality of ridges are formed over the entire circumference along the axial direction of the reciprocating shaft,
The backup ring is characterized in that the length of the protrusion is shorter than the overall length of the backup ring in the axial direction.
2.
The plurality of ridges include a hydraulic side ridge group and an atmospheric side ridge group formed on the atmosphere side with respect to the hydraulic side ridge group,
2. The backup ring according to claim 1, wherein the hydraulic side ridge group and the atmospheric side ridge group have different angular positions with respect to the backup ring.
3.
3. The backup ring according to claim 2, wherein the hydraulic side ridge group and the atmospheric side ridge group do not overlap in the circumferential direction.
4.
4. The backup ring according to the above 1, 2, or 3, wherein the length of the ridge is 40% to 50% of the entire length of the backup ring in the axial direction.
5.
5. The backup ring according to any one of 1 to 4, wherein the plurality of protrusions are formed at equal angular intervals.
6.
The backup ring according to any one of 1 to 5, wherein a width of each of the protrusions at both ends is smaller than that of a center portion.

  According to the present invention, it is possible to provide a backup ring that can sufficiently prevent a sliding surface of a reciprocating shaft from being damaged even when a metal foreign substance mixed in oil enters between the reciprocating shaft and the reciprocating shaft. it can.

Longitudinal sectional view showing a rod seal portion using the first embodiment of the backup ring of the present invention. Longitudinal sectional view showing the backup ring shown in FIG. A side view (a), a perspective view (b), and a plan view (c) showing a ridge of the backup ring shown in FIG. Side view showing a reciprocating shaft using the backup ring of the present invention Longitudinal sectional view showing a second embodiment of the backup ring of the present invention. Longitudinal sectional view showing a conventional backup ring Side view showing a reciprocating shaft using a conventional backup ring

  Hereinafter, embodiments for carrying out the present invention will be described.

[First Embodiment]
FIG. 1 is a longitudinal sectional view showing a rod seal portion using the first embodiment of the backup ring of the present invention.

  The first embodiment of the backup ring 1 is used for a rod seal portion in a hydraulic cylinder or a suspension of a construction machine, a shock absorber of an automobile, or the like. This embodiment is an example of application to a rod seal portion used in a hydraulic cylinder (not shown in its entirety) used as an actuator of a construction machine, a civil engineering machine, a transport vehicle, or the like.

  As shown in FIG. 1, the rod seal portion includes a reciprocating shaft (piston rod) 102 as a movable portion that reciprocates linearly, and a housing (cylinder housing) 101 as a fixed portion that houses the reciprocating shaft 102. It is provided between. The rod seal portion is supported by the housing 101. The housing 101 has an opening 101a on the atmosphere side (the left side in FIG. 1) and a closed lid on the hydraulic side (the right side and the inside side in FIG. 1).

  In the housing 101, a reciprocating shaft 102 is arranged. The reciprocating shaft 102 has a distal end projecting toward the atmosphere from an opening 101 a of the housing 101, and a proximal end located on the hydraulic pressure side in the housing 101. The reciprocating shaft 102 is capable of reciprocating in the axial direction as indicated by an arrow A in FIG.

  The rod seal portion includes a rod packing 2, a buffer ring 3 disposed on the hydraulic side of the rod packing 2, and a dust seal 4 disposed on the atmospheric side of the rod packing 2. Therefore, the buffering 3, the rod packing 2, and the dust seal 4 are arranged in this order from the hydraulic side to the atmospheric side.

  The rod packing 2 serves as a main seal for preventing leakage of hydraulic oil to the outside. The rod packing 2 is mainly composed of an annular U packing made of a rubber-like elastic material such as urethane, and a flat washer-shaped backup ring is attached to the U packing. Are adjacent to each other. The rod packing 2 has its inner peripheral surface pressed against the outer peripheral surface (sliding surface) 102a of the reciprocating shaft 102 to seal a gap between the rod packing 2 and the outer peripheral surface 102a. The rod packing 2 is housed in an annular groove 103 provided on the inner peripheral surface of the housing 101.

  The dust seal 4 is integrally formed of an elastic material into an annular shape. As a material forming the dust seal 4, as a resilient material capable of sealing a gap between the outer peripheral surface (sliding surface) 102a of the reciprocating shaft 102, various kinds of synthetic resin materials such as rubber, urethane, and PTFE are preferable. The dust seal 4 is housed in an atmosphere-side mounting groove 104 provided on the inner peripheral surface of the housing 101.

  The buffering 3 has a role of buffering shock pressure and fluctuating pressure at the time of a high load, and preventing the high-temperature hydraulic oil from flowing into the rod packing 2, thereby maintaining the durability of the rod packing 2. Fulfill.

  The buffer ring 3 has an annular U-packing 5 mainly made of a rubber-like elastic material such as urethane, and has a structure in which the backup ring 1 is fitted into a heel portion of the U-packing 5. The U packing 5 is in contact with the outer peripheral surface 102a of the reciprocating shaft 102. The U packing 5 is supported by the backup ring 1, so that even if an excessive pressure is applied, the U packing 5 is prevented from being deformed and protruding into the annular gap between the reciprocating shaft 102 and the housing 101. The backup ring 1 is deformed by pressure and adheres to the reciprocating shaft 102, thereby suppressing the U packing 5 from protruding into the annular gap.

  The U packing 5 and the backup ring 1 are both housed in a hydraulic side mounting groove 105 provided on the inner peripheral surface of the housing 101. The hydraulic side mounting groove 105 is located on the hydraulic side in the housing 101, and is formed coaxially with the reciprocating shaft 102 so as to surround the outer peripheral surface 102 a of the reciprocating shaft 102.

  FIG. 2 is a longitudinal sectional view showing the backup ring shown in FIG.

  As shown in FIG. 2, the backup ring 1 is formed in an annular shape from a hard material such as a polyamide resin. In the backup ring 1, a plurality of ridges 6 are formed over the entire circumference along the axial direction of the reciprocating shaft 102 on the inner peripheral surface 1 a facing the outer peripheral surface 102 a of the reciprocating shaft 102.

  The outer peripheral surface 102a of the reciprocating shaft 102 contacts only the tops of the ridges 6 and does not contact the inner peripheral surface 1a other than the ridges 6. An annular gap is formed between the inner peripheral surface 1a other than the protrusions 6 and the outer peripheral surface 102a of the reciprocating shaft 102.

  FIG. 3 is a side view (a), a perspective view (b), and a plan view (c) showing the ridges of the backup ring shown in FIG.

  As shown in FIGS. 3 (a) and 3 (b), the height of each ridge 6 is such that the annular gap between the inner peripheral surface 1a and the outer peripheral surface 102a other than the ridge 6 is formed by pressure of the U packing 5. The height of the gap is such that the gap does not protrude even if deformed, for example, about 0.05 mm. The annular gap between the inner peripheral surface 1a other than the ridge 6 and the outer peripheral surface 102a is for allowing metal foreign matters mixed in the oil film on the outer peripheral surface 102a of the reciprocating shaft 102 to pass.

  As shown in FIG. 3B, each protrusion 6 has a shape (kamaboko shape) that is a part of a cylinder having a radius of about 0.5 mm, for example. 3A, the upper surface of the both ends 61 of each ridge 6 (the inner peripheral side of the backup ring 1) has an arc shape with a radius of about 0.2 mm, for example.

  In addition, as shown in FIG. 3C, it is also preferable that the cross-sectional shape of the ridge 6 is elliptical, and the width at both ends 61 is smaller than that at the center 62. Thereby, metal foreign matter mixed in the oil film on the outer peripheral surface 102a can be satisfactorily passed.

  The length T of the ridge 6 is shorter than the overall length L of the backup ring 1 in the axial direction. The length T of the ridge 6 is preferably 40% (2/5) to 50% (1/2) with respect to the overall axial length L of the backup ring 1, and is preferably about 40% (2/5). Is more preferable.

  Preferably, the plurality of ridges 6 are formed at equal angular intervals with respect to the backup ring 1. For example, 90 ridges 6 can be formed at equal angular intervals (4 ° intervals).

  The length, circumferential width and number of the ridges 6 are set so that the inner peripheral surface 1 a other than the ridges 6 does not contact the outer peripheral surface 102 a of the reciprocating shaft 102 even when pressure is applied to the backup ring 1. Is set. Further, when the contact area between each ridge 6 and the outer peripheral surface 102a of the reciprocating shaft 102 decreases, the surface pressure increases, and the abrasion of the ridge 6 and the reciprocating shaft 102 increases. The length, width and number are determined in consideration of the pressure and temperature conditions to be used. However, in order to allow the metallic foreign matter mixed in the oil film to pass therethrough, the circumferential length and width (top area) of the ridge 6 should be small, and the number should be small.

  When the reciprocating shaft 102 has a large diameter, it is preferable to increase the number of the ridges 6 so that the interval between the ridges 6 does not become too large.

  FIG. 4 is a side view showing a reciprocating shaft using the backup ring of the present invention.

  In the buffer ring 3 using the backup ring 1, the reciprocating shaft 102 moves even if metal foreign matter mixed in oil enters between the backup ring 1 and the outer peripheral surface 102 a of the reciprocating shaft 102. In addition, since the metallic foreign matter passes through the annular gap between the inner peripheral surface 1a and the outer peripheral surface 102a, no contact pressure is generated between the metallic foreign matter and the reciprocating shaft 102 as shown in FIG. The outer peripheral surface 102a of the reciprocating shaft 102 is not damaged.

  FIG. 5 is a longitudinal sectional view showing a second embodiment of the backup ring of the present invention.

  In the backup ring 1, as shown in FIG. 5, the plurality of ridges 6 include a hydraulic side ridge group 6a and an atmosphere side ridge group 6b formed on the atmosphere side with respect to the hydraulic side ridge group 6a. It may be composed of In this case, the projections 6 have different angular positions with respect to the backup ring 1.

  As described above, in the backup ring 1 having the hydraulic side ridge group 6a and the atmospheric side ridge group 6b, the ridge 6 of the hydraulic side ridge group 6a and the ridge 6 of the atmospheric side ridge group 6b are connected to the backup ring. When the reciprocating shaft 102 moves, the oil film on the outer peripheral surface 102a of the reciprocating shaft 102 can be agitated when the reciprocating shaft 102 moves, thereby preventing the metal foreign matter from staying in the oil film. be able to. The prevention of stagnation of the metal foreign matter prevents the outer peripheral surface 102a of the reciprocating shaft 102 from being damaged.

  In the backup ring 1 of this embodiment, by increasing the contact area between the ridge 6 and the reciprocating shaft 102, the wear resistance of the ridge 6 and the reciprocating shaft 102 can be improved, and the pressure can be reduced. This prevents the backup ring 1 from being deformed. Further, it is possible to prevent the backup ring 1 from being twisted due to the contact between the inner peripheral surface having no projection 6 and the reciprocating shaft 102.

The length T _o of the ridge 6 of the hydraulic side protrusion group 6a is preferably shorter than the overall axial length L of the backup ring 1. The length T _o of the ridge 6 of the hydraulic side protrusion group 6a is more preferably from 40% to 50% of the total axial length L of the backup ring 1, more preferably about 40% .

The length T _a ridge 6 on the atmosphere side protrusion group 6b is preferably shorter than the overall axial length L of the backup ring 1. The length T _a ridge 6 on the atmosphere side protrusion group 6b is more preferably from 40% to 50% of the total axial length L of the backup ring 1, more preferably about 40%.

Further, the sum of the length T _a ridge 6 of the length T _o and the atmosphere-side protrusion group 6b ridges 6 of the hydraulic side protrusion group 6a is preferably shorter than the axial length L of the backup ring . Further, it is preferable that the ridge 6 of the hydraulic side ridge group 6a and the ridge 6 of the atmospheric side ridge group 6b do not overlap in the circumferential direction of the backup ring 1.

  The ridges 6 of the hydraulic side ridge group 6a are preferably formed at equal angular intervals, and the ridges 6 of the atmospheric side ridge group 6b are preferably formed at equal angular intervals. It is sufficient that the ridges of each ridge group are formed at equal angular intervals.

  Specific configurations, shapes, materials, operations, numerical values, and the like in the description of each of the above embodiments are merely examples for describing the present invention, and the present invention may be interpreted in a limited manner. Not be.

1: Backup ring 1a: Inner peripheral surface 2: Rod packing 3: Buffering 4: Dust seal 5: U packing 6: Ridge 61: Both ends 62: Central part 6a: Hydraulic side ridge group 6b: Atmospheric side ridge group 101: Housing 101a: Opening 102: Reciprocating shaft (piston rod)
102a: Outer peripheral surface 103: Annular groove 104: Atmospheric side annular groove 105: Hydraulic side annular groove

Claims (6)

A backup ring that is disposed in the housing and supports an annular packing that is in contact with the outer peripheral surface of a reciprocating shaft whose distal end projects toward the atmosphere and whose proximal end is located on the hydraulic side,
On the inner peripheral surface facing the outer peripheral surface of the reciprocating shaft, a plurality of ridges are formed over the entire circumference along the axial direction of the reciprocating shaft,
The backup ring is characterized in that the length of the protrusion is shorter than the overall length of the backup ring in the axial direction. The plurality of ridges include a hydraulic side ridge group and an atmospheric side ridge group formed on the atmosphere side with respect to the hydraulic side ridge group,
2. The backup ring according to claim 1, wherein angular positions of the hydraulic side ridge group and the atmospheric side ridge group with respect to the backup ring are different from each other.   The backup ring according to claim 2, wherein the hydraulic side ridge group and the atmosphere side ridge group do not overlap in the circumferential direction.   4. The backup ring according to claim 1, wherein a length of the ridge is 40% to 50% of an overall length of the backup ring in an axial direction. 5.   The backup ring according to any one of claims 1 to 4, wherein the plurality of ridges are formed at equal angular intervals.   The backup ring according to any one of claims 1 to 5, wherein the protrusion has a narrower width at both ends than at a center.

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