JP2018204761A - Dust seal - Google Patents

Abstract

To make the durability of a dust seal continue for a long period of time.SOLUTION: A seal member 52 of a dust seal 51 formed of an elastic member is fixed to a cylinder housing 13 at an external peripheral side, and slidably and tightly adheres to a piston rod 12 at an internal peripheral side in order to seal a clearance between, for example, the cylinder housing 13 (fixed part) and the piston rod 12 (movable part) which linearly reciprocates in the cylinder housing 13. In order to protect the dust seal 51 from the hardening of unintentionally-coated paint, the adhesion of a solvent, and a collision of foreign matters such as sediments, stones and woods, an exposed face 51s of a seal member 52 facing an atmospheric side A is coated with a resin-made protection film 57. The protection film 57 whirls into a region contacting with the cylinder housing 13, and protects the dust seal 51 from the intrusion of water.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a dust seal used in a reciprocating device such as a hydraulic cylinder or an operation valve.

  In reciprocating devices such as hydraulic cylinders and operation valves, a dust seal is required between the rod that reciprocates and the housing that houses the rod to prevent the entry of sewage and dust from the outside. In reciprocating motion equipment used in construction machines, civil engineering machines, transport vehicles, etc. used in particularly harsh conditions, the dust seal is required to have high sealing ability and excellent durability.

  The causes of the deterioration of the durability of the dust seal include hardening of the applied paint, adhesion of solvent, water intrusion, collision of foreign matter such as earth, stone, and wood, solidification of foreign matter attached to the rod, and accumulation of dust in the seal part. There are outbreaks.

  The problem of hardening of the paint is that when the paint is applied to the peripheral parts of the reciprocating motion equipment where the dust seal is used, the paint may also be applied to the dust seal exposed to the outside. Occurs. The applied paint eventually hardens and adheres to the dust seal, resulting in an operating resistance that impairs the durability of the dust seal. Moreover, if a crack occurs in the solidified paint, it may propagate and cause the dust lip to crack.

  Patent Document 1 describes an invention in which an oil-repellent resin such as PTFE (polytetrafluoroethylene) is applied to the atmosphere-side surface of a dust seal (see paragraphs [0013] and [0025] of Patent Document 1). ). According to Patent Document 1, this solves the problem caused by the solidification of the paint (see paragraphs [0028] to [0032] of Patent Document 1).

  Patent Document 2 describes an invention in which a scraper is installed on the atmosphere side of a dust seal (see Patent Document 2, page 4, line 2 to page 5, line 5, FIG. 1). The scraper has an outer peripheral side attached to a cylinder that houses the rod, extends in a curved manner along a surface of the dust seal on the atmosphere side, and makes the inner peripheral side contact the rod. According to Patent Document 2, the dust seal is protected from the collision of the foreign matter by providing the scraper, the dust accumulation is prevented from occurring in the seal portion, and the foreign matter is scraped off from the reciprocating rod. (Refer to page 7, line 1 to line 4, page 7, line 16 to page 8, line 4, page 8, line 16 to page 9, line 7).

JP-A-11-166632 Japanese Utility Model Publication No. 03-000168

  The inventions described in Patent Documents 1 and 2 play a role in improving the durability of the dust seal. However, there is room for improvement in the following points.

  In the invention described in Patent Document 1, the atmosphere side surface of the dust seal is not entirely covered with resin, and the resin does not reach the contact area with the fixing portion that fixes the dust seal. It is surmised that this is because this part is a metal ring. However, since the resin does not go around, water such as sewage enters between the housing and the metal ring, which may gradually reduce the sealing performance of the dust seal.

  In the invention described in Patent Document 2, plastic deformation is likely to occur in the scraper because of the structure in which the curved scraper elastically contacts the rod. For this reason, the sealing performance of the dust seal may gradually deteriorate.

  As described above, the inventions described in Patent Documents 1 and 2 contribute to the improvement of the durability of the dust seal, but there is room for improvement in the durability.

  An object of the present invention is to make it possible to maintain the durability of a dust seal for a long period of time.

  One aspect of the dust seal of the present invention includes a fixed portion, a movable portion that reciprocates linearly relative to the fixed portion, an outer peripheral side fixed to the fixed portion, and an inner peripheral side freely slidable to the movable portion. A sealing member made of an elastic member in close contact with the resin, and a resin protective film that covers the atmosphere-side surface of the sealing member up to a region in contact with the fixing portion.

  One aspect of the dust seal of the present invention includes a fixed portion, a movable portion that reciprocates linearly relative to the fixed portion, an outer peripheral side fixed to the fixed portion, and an inner peripheral side freely slidable to the movable portion. A sealing member made of an elastic member that is in close contact with the protective member, an outer peripheral side of the sealing member is fixed to cover the air side surface of the sealing member, and an inner peripheral surface of the movable member is opened with a gap therebetween, and the protection A scraper made of an elastic body fixed to the inner peripheral side of the cover and slidably in close contact with the movable part from a direction orthogonal to the axial direction of the movable part.

  According to the present invention, the durability of the dust seal can be maintained for a long period of time, and the sealing performance can be maintained over a long period of time.

It is an example of application to a rod sealing system, and is a longitudinal front view showing individual seal structures with the whole being halved around the axis of the piston rod. FIG. 3 is an enlarged longitudinal front view showing the dust seal of the first embodiment. The longitudinal cross-sectional front view which expands and shows the dust seal of 2nd Embodiment.

  Embodiments will be described with reference to the drawings. The present embodiment is an application example to a rod sealing system 11 employed in a hydraulic cylinder 1 (not shown as a whole) used as an actuator for construction machines, civil engineering machines, transport vehicles and the like.

[Rod sealing system]
As shown in FIG. 1, the rod sealing system 11 is provided between a piston rod 12 as a movable part that reciprocates linearly and a cylinder housing 13 as a fixed part that houses the piston rod 12. The rod sealing system 11 includes a rod packing 31, a buffer ring 41 disposed on the hydraulic side O of the rod packing 31, and a dust seal 51 disposed on the atmosphere side A of the rod packing 31. Therefore, the buffer ring 41, the rod packing 31, and the dust seal 51 are arranged in this order from the hydraulic side O toward the atmosphere side A.

  The rod packing 31 serves as a main seal that prevents leakage of hydraulic fluid to the outside. The rod packing 31 has a structure in which a flat washer-like backup ring 33 is adjacent to the U-packing 32 mainly. Is. Both the U packing 32 and the backup ring 33 are accommodated in a mounting groove 14 provided on the inner peripheral surface of the cylinder housing 13.

  The buffer ring 41 functions to maintain the durability of the rod packing 31 by buffering the impact pressure and the fluctuating pressure at the time of high load, or by preventing high temperature hydraulic oil from flowing into the rod packing 31 side. Plays. Such a buffer ring 41 has a structure in which an annular U packing 42 is used as a main body and a backup ring 43 is fitted into a heel portion 42a of the U packing 42. Both the U packing 42 and the backup ring 43 are accommodated in a mounting groove 15 provided on the inner peripheral surface of the cylinder housing 13.

  The dust seal 51 is a seal for preventing muddy water and dust from entering the inside of the rod sealing system 11 from the atmosphere side A, and mainly includes a seal member 52. The seal member 52 is an annular elastic member formed of urethane, and is accommodated in the mounting groove 16 provided on the inner peripheral surface of the cylinder housing 13. On the inner peripheral surface of the seal member 52, a seal lip 53 and a dust lip 54 project from the hydraulic side O and the atmosphere side A, respectively, and both are elastically in close contact with the piston rod 12.

  Such a seal member 52 has a metal ring 55 embedded therein. The metal ring 55 is a metal annular member having an L-shaped cross section, and one side extends along the bottom of the mounting groove 16 and the other side extends toward the piston rod 12. That is, the metal ring 55 extends in the axial direction of the piston rod 12 and the direction orthogonal thereto.

[First Embodiment]
A first embodiment of the dust seal 51 will be described with reference to FIG. The present embodiment is an example of a dust seal 51 applied to the rod sealing system 11 shown in FIG.

  In FIG. 2, the piston rod 12 is shown virtually. Reference symbol C is the axis of the piston rod 12. When the rod sealing system 11 is incorporated in the hydraulic cylinder 1, the dust seal 51 is in close contact with the piston rod 12 due to the bending of the seal lip 53 and the dust lip 54. 2 shows the seal lip 53 and the dust lip 54 before being bent, and the portion protruding from the outer peripheral surface of the piston rod 12 toward the axis C is a portion to be tightened. .

  The dust seal 51 has a metal ring 55 embedded in the atmosphere side A, leaving the thickness of the seal member 52 as an elastic member. Therefore, the exposed surface 51 s which is the surface facing the atmosphere side A of the dust seal 51 is a seal member 52 made of urethane as a whole, and the metal ring 55 is not exposed on this surface.

  On the exposed surface 51s of the dust seal 51 facing the atmosphere side A, a plurality of holes 56 are provided. These holes 56 are holes provided as a result of a jig for supporting the metal ring 55 and preventing the displacement thereof when the dust seal 51 is manufactured.

  The dust seal 51 of the present embodiment covers the exposed surface 51 s of the seal member 52 facing the atmosphere side A with a protective film 57. The protective film 57 extends to the area in contact with the cylinder housing 13 and covers the entire exposed surface 51 s of the dust seal 51. The protective film 57 is made of nylon, and is integrally formed with a sealing member 52 made of urethane.

  In such a configuration, the rod sealing system 11 according to the present embodiment is exposed to severe conditions because it is used in the hydraulic cylinder 1 used as an actuator of a construction machine, a civil engineering machine, a transport vehicle, and the like. Durability is easily lost.

  For example, paint may be applied to the hydraulic cylinder 1 for dust prevention. At this time, the paint also adheres to the dust seal 51 of the rod sealing system 11 that should not be attached to the paint, and this hardens to impair the durability of the dust seal 51 or cause the dust lip 54 to crack. Cause. On the other hand, since the exposed surface 51s facing the atmosphere side A is covered with the protective film 57 in the dust seal 51 of the present embodiment, the seal member 52 is not easily damaged even when the paint is cured, and its durability Sex is secured.

  The protective film 57 also damages or corrodes the seal member 52 even when a solvent that damages or corrodes urethane, which is the material of the seal member 52, adheres to the dust seal 51. Protect from.

  Further, the protective film 57 protects the seal member 52 from water intrusion into the dust seal 51 and collision of foreign matters such as earth and sand, stone, and wood.

  Moreover, since the protective film 57 extends to the area in contact with the cylinder housing 13 and completely covers the exposed surface 51s of the dust seal 51, it can be reliably prevented from applying paint, adhering solvent, entering water, and colliding with foreign matter. The seal member 52 can be protected. This makes it possible to maintain high durability over a long period of time.

  At this time, the exposed surface 51s of the seal member 52 facing the atmosphere side A is opened with a hole 56 to expose the metal ring 55. However, since the metal ring 55 is embedded in the seal member 52, this portion is The sealing property is high, and there is no inconvenience that water enters.

  In the present embodiment, the seal member 52 is made of urethane, and the protective film 57 is made of nylon. For this reason, the protective film 57 can be integrally formed with the seal member 52, and the manufacture thereof can be facilitated.

  In the present embodiment, the dust seal 51 has a metal ring 55 having an L-shaped cross section embedded in the atmosphere A while leaving the thickness of the seal member 52 that is an elastic member. Therefore, even if the metal ring 55 is embedded, a protective film 57 is formed on the exposed surface 51 s of the seal member 52 facing the atmosphere side A to reach the area in contact with the cylinder housing 13, thereby exposing the dust seal 51. 51s can be entirely covered.

[Second Embodiment]
A second embodiment of the dust seal 51 will be described with reference to FIG. This embodiment is an example different from the first embodiment of the dust seal 51 applied to the rod sealing system 11 shown in FIG. The same parts as those of the first embodiment are denoted by the same reference numerals, and the description thereof is also omitted.

  The dust seal 51 of the present embodiment covers the exposed surface 51 s of the seal member 52 facing the atmosphere side A with a protective cover 71. A scraper 81 that is in close contact with the piston rod 12 is fixed to the protective cover 71.

  The protective cover 71 is an annular metal member, and the outer peripheral side is fixed to the cylinder housing 13. That is, a flat washer-shaped retaining ring 72 is embedded in the inner peripheral surface of the cylinder housing 13 so as to face the exposed surface 51 s of the seal member 52 with a space therebetween. The outer peripheral side of the protective cover 71 is sandwiched between the exposed surface 51 s of the seal member 52 and the retaining ring 72. At this time, the facing distance between the exposed surface 51 s of the seal member 52 and the retaining ring 72 is set to be slightly shorter than the thickness of the protective cover 71. As a result, the protective cover 71 is sandwiched between the exposed surface 51 s of the seal member 52 and the retaining ring 72 with the seal member 52 slightly deformed, and is fixed by the elastic restoring force of the seal member 52.

  The protective cover 71 whose outer peripheral side is fixed to the cylinder housing 13 is bent toward the atmosphere side A so as to avoid interference with the dust seal 51. The inner peripheral side is bent in a direction orthogonal to the axial direction of the piston rod 12. As a result, the inner peripheral side of the protective cover 71 faces the outer peripheral surface of the piston rod 12 with a gap G from the direction orthogonal to the axial direction.

  The scraper 81 is an annular member made of, for example, urethane, rubber, PTFE (polytetrafluoroethylene) or the like. On the inner peripheral side of the protective cover 71, a stepped portion 73 is formed on the hydraulic side O side, and the scraper 81 is bonded and fixed to the stepped portion 73. In this state, the scraper 81 keeps the inner peripheral surface in close contact with the outer peripheral surface of the piston rod 12.

  In such a configuration, the rod sealing system 11 according to the present embodiment is exposed to severe conditions because it is used in the hydraulic cylinder 1 used as an actuator of a construction machine, a civil engineering machine, a transport vehicle, and the like. Durability is easily lost.

  For example, paint may be applied to the hydraulic cylinder 1 for dust prevention. At this time, the paint also adheres to the dust seal 51 of the rod sealing system 11 that should not be attached to the paint, and this hardens to impair the durability of the dust seal 51 or cause the dust lip 54 to crack. Cause. On the other hand, in the dust seal 51 of the present embodiment, the exposed surface 51s on the atmosphere side A of the seal member 52 is entirely covered with the protective cover 71, so that the coating of the paint on the seal member 52 is completely prevented. be able to. Therefore, the seal member 52 is prevented from being damaged by the application of the paint, and the durability is ensured.

  Further, the protective cover 71 completely prevents the solvent that damages or corrodes urethane, which is the material of the seal member 52, from adhering to the seal member 52. Therefore, the seal member 52 is prevented from being damaged by the adhesion of the solvent, and the durability is ensured.

  Further, the protective cover 71 protects the seal member 52 from collision of foreign matter such as earth and sand, stone, and wood with respect to the dust seal 51, and also protects the seal member 52 from the penetration of water into the dust seal 51 together with the scraper 81.

  The scraper 81 prevents the foreign matter from adhering to the piston rod 12, scraping off the foreign matter that is solidifying, and the generation of dust accumulation in the seal portion as the piston rod 12 reciprocates linearly. It also demonstrates the function of

  At this time, since the protective cover 71 is made of metal having excellent strength, the protective cover 71 exhibits a large impact resistance against foreign matters such as earth and sand, stones, and wood, and can reliably protect the seal member 52. On the other hand, the scraper 81 is formed of a material having an optimum hardness so as to prevent water from entering the seal portion and generation of dust accumulation, and to prevent adhesion and solidification of foreign matter to the piston rod 12. Accordingly, the scraper 81 performs its function without causing damage to the piston rod 12. That is, in the present embodiment, since the protective cover 71 and the scraper 81 are configured separately, a material suitable for each role can be selected, and the functions required for the protective cover 71 and the scraper 81 can be selected. The required functions can be realized at a high level.

  Therefore, according to the dust seal 51 of the present embodiment, the sealing member is reliably secured from the application of the paint, the adhesion of the solvent, the intrusion of water, the collision of the foreign matter, the adhesion and solidification of the foreign matter with respect to the piston rod 12, 52 can be protected. This makes it possible to maintain high durability over a long period of time.

  In the present embodiment, the dust seal 51 has a metal ring 55 having an L-shaped cross section embedded in the atmosphere A while leaving the thickness of the seal member 52 that is an elastic member. The protective cover 71 is sandwiched between a retaining ring 72 that protrudes from the cylinder housing 13 toward the piston rod 12 and an exposed surface 51 s on the atmosphere side A of the seal member 52. Therefore, the outer peripheral side of the protective cover 71 is in close contact with the seal member 52, and the sealability of this portion can be improved.

[Modification]
In implementation, various modifications and changes are possible.

  For example, in the first embodiment, an example in which the protective film 57 is integrally formed with the seal member 52 is shown. However, the protective film 57 does not necessarily have to be integrally formed with the seal member 52. It may be adhered to the exposed surface 51s.

  The materials of the seal member 52, the protective film 57, the protective cover 71, and the scraper 81 are not limited to those introduced in the above embodiment, and various materials may be used as appropriate.

  In addition, various modifications and changes can be made in the implementation.

1 Hydraulic cylinder 11 Rod sealing system 12 Piston rod (movable part)
13 Cylinder housing (fixed part)
14 mounting groove 15 mounting groove 16 mounting groove 31 rod packing 32 U packing 33 backup ring 41 buffer ring 42 U packing 42a heel portion 43 backup ring 51 dust seal 51s exposed surface (atmosphere side surface of seal member)
52 Seal member 53 Seal lip 54 Dustrip 55 Metal ring 56 Hole 57 Protective film 71 Protective cover 72 Retaining ring 73 Step part 81 Scraper A Atmosphere side O Hydraulic side G Gap

Claims (5)

A fixed part;
A movable part that reciprocates linearly relative to the fixed part;
A seal member made of an elastic member whose outer peripheral side is fixed to the fixed portion and whose inner peripheral side is slidably in close contact with the movable portion;
A protective film made of resin that covers the atmosphere-side surface of the sealing member up to the region in contact with the fixed portion;
A dust seal characterized by comprising: The seal member is made of urethane, and the protective film is made of nylon.
The dust seal according to claim 1. The seal member is embedded in a metal ring having an L-shaped cross section that is fixed to the fixing portion, leaving the thickness of the elastic member on the atmosphere side.
The dust seal according to claim 1 or 2, wherein the dust seal is provided. A fixed part;
A movable part that reciprocates linearly relative to the fixed part;
A seal member made of an elastic member whose outer peripheral side is fixed to the fixed portion and whose inner peripheral side is slidably in close contact with the movable portion;
A protective cover whose outer peripheral side is fixed to the fixed part and covers the air side surface of the seal member, and whose inner peripheral side faces the movable part with a gap;
A scraper made of an elastic body fixed to the inner peripheral side of the protective cover and slidably in close contact with the movable part from a direction perpendicular to the axial direction of the movable part;
A dust seal characterized by comprising: The seal member is embedded in a metal ring having an L-shaped cross section that is fixed to the fixing portion, leaving the thickness of the elastic member on the atmosphere side,
The protective cover is sandwiched between a retaining ring protruding from the fixed portion toward the movable portion and a surface on the atmosphere side of the seal member.
The dust seal according to claim 4.

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