JP2016003659A - Dust seal device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the lowering of seal performance caused by the settling of a material, in a dust seal device.SOLUTION: A dust seal device comprises a dust seal main body 1 which is attached to an annular groove 113 formed at an internal peripheral face of an external peripheral member 110. The dust seal main body 1 comprises a dust lip 12 which slidably and closely contacts with an external peripheral face of an internal peripheral face member 120 which is relatively and movably inserted into an internal periphery of the external peripheral member 110 in an axial direction, and whose tip closely contacts with an inside face of the annular groove 113. A pressurization hole 22 which can pressure-insert grease G into a sealed space S3 between the dust lip 12 and the annular groove 113 is opened at the external peripheral member 110, and a plug member 3 which holds the grease pressure of the sealed space S3 is attached to the pressurization hole 22.

Description

  The present invention relates to a dust seal device used as a sealing means for sealing an annular gap between two members that reciprocate in the axial direction, such as between a cylinder and a rod of a hydraulic cylinder device of a construction machine or an industrial machine.

  In a hydraulic cylinder device used in construction machinery, etc., a plurality of axial seals are used to seal an annular gap between a cylinder and a rod that reciprocates in the axial direction by a piston that receives the hydraulic pressure in the cylinder. Is used.

  FIG. 8 shows a shaft seal portion of this type of hydraulic cylinder device according to the prior art, and an annular shape between a cylinder 110 in the hydraulic cylinder device and a rod 120 that is reciprocally inserted into the shaft hole. The hydraulic oil in the oil chamber S1 on the right side in the figure is prevented from leaking to the external space S2 on the left side in the figure, being interposed in the gap and held in the annular grooves 111 to 113 formed on the inner peripheral surface of the cylinder 110. A rod seal 210 and buffering that is located on the oil chamber S1 side from the rod seal 210 to buffer impact pressure and fluctuating pressure at high load, or prevent high temperature hydraulic oil from directly contacting the rod seal 210 220 and a dust seal 230 that is located outside the rod seal 210 and prevents intrusion of muddy water and dust from the external space S2.

  Among them, the dust seal 230 includes a metal reinforcing ring 231, a dust strip 232 and an oil lip 233 that are integrally formed with the reinforcing ring 231 and are slidably in close contact with the outer peripheral surface of the rod 120. It is fixed to the outermost annular groove 113 on the inner peripheral surface by a stop ring 234.

JP 2009-174555 A

  In the dust seal 230, the dust lip 232 and the oil lip 233 that are slidably in contact with the outer peripheral surface of the rod 120 are formed of a flexible material such as rubber or urethane. As a result, stress relaxation called “sagging” occurs, and if the interference of the dust strip 232 with respect to the outer peripheral surface of the rod 120 decreases, there is a concern that the intrusion of muddy water and dust from the external space S2 may be permitted.

  Therefore, measures have been taken to improve the material's settling resistance or to increase the initial tightening allowance of the dust strip 232, but a material with high heat resistance was used in order to improve the settling resistance of the material. In this case, the material cost increases, and if the initial tightening allowance for the outer peripheral surface of the rod 120 is increased, the operability of the rod 120 is adversely affected, or the amount of heat generated by sliding increases and the material is likely to be thermally deteriorated. In addition, sufficient sag resistance may not be obtained.

  The present invention has been made in view of the above points, and an object of the present invention is to prevent a sealing performance from being deteriorated due to settling of a material in a dust seal device.

The present invention employs the following means in order to achieve the above-described object.
That is, the dust seal device of the present invention includes a dust seal main body mounted in an annular groove formed on the inner peripheral surface of the outer peripheral member, and the dust seal main body is inserted into the inner periphery of the outer peripheral member so as to be capable of axial relative movement. A dust strip that is slidably brought into close contact with the outer peripheral surface of the inner peripheral member and whose tip is in close contact with the inner side surface of the annular groove is provided, and the outer member is sealed between the dust strip and the annular groove. A pressurizing hole capable of press-fitting grease is formed in the space, and a plug member for holding the grease pressure in the sealed space is attached to the pressurizing hole (claim 1).

  In the dust seal device having the above configuration, the dust seal body is mounted in an annular groove formed on the inner peripheral surface of the outer peripheral member, and the dust lip is slidably brought into close contact with the outer peripheral surface of the inner peripheral member. This prevents muddy water and dust from entering the annular gap between the outer peripheral member and the inner peripheral member. When the tightening margin on the outer peripheral surface of the inner peripheral member decreases due to the settling of the dust lip, grease is pressed into the sealed space between the annular groove and the dust lip through the pressurizing hole formed in the outer peripheral member. If the grease pressure in the sealed space is maintained by the plug member, the tightness of the dust strip with respect to the outer peripheral surface of the inner peripheral member is recovered, so that the sealing performance against external muddy water and dust is maintained.

The present invention may further employ the following means in order to achieve the above object.
That is, in the dust seal device (Claim 1) configured as described above, the outer peripheral member is composed of the outer peripheral member main body and a pressing plate attached to the end of the outer peripheral member main body, and the annular groove for mounting the dust seal main body has An inner surface of an annular groove formed between the plates and in close contact with the tip of the dust lip of the dust seal body is formed in the pressing plate, and a pressure hole is formed in the pressing plate. (Claim 2).

  If comprised in this way, the means which prevents a dust seal main body from detaching from an annular groove, the means which forms sealed space between dust strips, and the means which press-fits grease to this sealed space can serve as a press plate. it can.

  Further, in the dust seal device having the above structure (claim 1 or 2), the plug member is formed of a grease nipple that allows the grease to be externally pressed and prevents the grease from flowing out. ).

  If comprised in this way, the press injection of the grease to the sealed space between the annular groove and the dust lip and the maintenance of the grease pressure in the sealed space can be easily performed.

  Further, in the dust seal device having the above structure (Claim 1 or 2), the plug member injects grease into the sealed space between the annular groove and the dust lip through the pressure hole, and then screwed into the pressure hole. (Claim 4).

  According to this structure, after filling the sealed space between the annular groove and the dust lip through the pressure hole, and then screwing the bolt into the pressure hole, the pressure is increased according to the screwing amount of the bolt. The grease in the pressure hole is pressed into the sealed space, and the pressure is maintained.

  Further, in the dust seal device having the above configuration (any one of claims 1 to 4), a sealing means is provided on the inner surface of the annular groove to which the tip of the dust lip is in close contact (claim 5).

  If comprised in this way, the fall of the grease pressure by the leak of the grease from the sealed space between an annular groove and a dust lip can be prevented, and the tightening margin of a dust lip can be maintained more favorably.

  According to the dust seal device of the present invention, even if the tightening allowance on the outer peripheral surface of the inner peripheral member decreases with time due to the settling of the dust strip, the tightening allowance of the dust strip on the outer peripheral surface of the inner peripheral member is reduced by the pressure of the grease. Is recovered and retained, and therefore excellent sealing performance against external muddy water and dust can be maintained over a long period of time.

1 is a half sectional view showing a first embodiment of a dust seal device according to the present invention by cutting along a plane passing through an axis together with a rod seal and a buffer ring in a shaft seal portion of a hydraulic cylinder device. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a first embodiment of a dust seal device according to the present invention, in which (A) shows a state before insertion of a rod, and (B) shows a state of insertion of a rod by cutting along a plane passing through an axis. It is sectional drawing. The principal part in 1st embodiment of the dust seal apparatus which concerns on this invention is shown, (A) is the figure seen from the direction parallel to an axial center, (B) is BOOB 'in (A). It is sectional drawing. In the first embodiment of the dust seal device according to the present invention, it is a half cross-sectional view showing a state where the tightening margin of the dust lip is recovered by press-fitting grease by cutting along a plane passing through the axis. The principal part in 2nd embodiment of the dust seal device which concerns on this invention is shown, (A) is the figure seen from the direction parallel to an axial center, (B) is BOOB 'in (A). It is sectional drawing. FIG. 7 is a half sectional view showing a third embodiment of the dust seal device according to the present invention by cutting along a plane passing through an axis. FIG. 6 is a half sectional view showing a fourth embodiment of a dust seal device according to the present invention by cutting along a plane passing through an axis. FIG. 10 is a half sectional view showing an example of a conventional dust seal device cut along a plane passing through an axis together with a rod seal and a buffer ring in a shaft seal portion of a hydraulic cylinder device.

  Hereinafter, preferred embodiments of a dust seal device according to the present invention will be described with reference to the drawings. 1 to 4 show the first embodiment.

  As shown in FIG. 1, a hydraulic cylinder device used in a construction machine or the like includes a cylinder 110 and a rod 120 that is inserted into a shaft hole of the cylinder 110 and reciprocates in an axial direction by a piston (not shown) that receives hydraulic pressure. A plurality of axial seals are used to seal the annular gap between the two.

  That is, the shaft seal portion of the illustrated hydraulic cylinder device includes a rod seal 210 that prevents the hydraulic oil in the right oil chamber S1 in FIG. 1 from leaking to the left external space S2 in FIG. A buffer ring 220 is provided on the oil chamber S1 side to buffer impact pressure and fluctuating pressure under high load, or to prevent high temperature hydraulic oil from directly contacting the rod seal 210, and provided outside the rod seal 210. The dust seal device 10 is provided. The cylinder 110 corresponds to the outer peripheral member main body described in claim 2, and the rod 120 corresponds to the inner peripheral member described in claim 1.

  Among these, the rod seal 210 includes a U-shaped packing 211 made of rubber material and a backup ring 212 made of synthetic resin material, and is attached to an annular groove 111 formed on the inner peripheral surface of the shaft hole of the cylinder 110. The buffer ring 220 includes a rubber elastic body buffer ring body 221 having a substantially U-shaped cross section and a resin backup ring 222, and an annular groove 111 for the rod seal 210 is formed on the inner circumferential surface of the shaft hole of the cylinder 110. Is also mounted in an annular groove 112 formed on the oil chamber S1 side.

  The dust seal device 10 includes a dust seal main body 1 mounted on an annular groove 113 formed on the inner circumferential surface of the shaft hole of the cylinder 110 on the outer space S2 side with respect to the annular groove 111 for the rod seal 210. The dust seal main body 1 includes a metal reinforcing ring 11 fitted to the inner peripheral surface of the annular groove 113, a dust lip 12 and an oil lip 13 integrally formed with the reinforcing ring 11 with a rubber elastic body, and an outer peripheral seal portion. 14 The dust lip 12 extends toward the external space S2 between the inner peripheral surface 2a of the holding plate 2 and the outer peripheral surface of the rod 120, and the oil lip 13 is opposite to the dust lip 12 (on the rod seal 210 side). ).

  A disc-shaped pressing plate 2 is attached to the outer end portion of the cylinder 110 by a plurality of bolts (not shown). The annular groove 113 for mounting the dust seal main body 1 is formed between the pressing plate 2 and the cylinder 110. That is, the pressing plate 2 constitutes a wall surface 113a on the outer space S2 side in the annular groove 113. The outer peripheral seal portion 14 in the dust seal main body 1 is in close contact with the inner side surface (the wall surface 113a) of the pressing plate 2.

  At the end of the inner peripheral surface 2a of the holding plate 2 on the outer space S2 side, an inward protruding edge 21 whose inner peripheral end faces the outer peripheral surface of the rod 120 with a slight gap is continuously provided in the circumferential direction. Is formed. As shown in FIG. 2A, in the state before the rod 120 is inserted, the tip of the dust lip 12 in the dust seal body 1 is not in contact with the inward protruding edge 21 of the pressing plate 2, and the oil lip 13 is not in contact with the inner surface of the annular groove 113 opposite to the pressing plate 2, but as shown in FIG. The front end of the strip 12 is brought into intimate contact with the inner surface of the inwardly protruding edge 21 of the pressing plate 2 with an appropriate margin, whereby the pressing plate 2 constituting a part of the annular groove 113 and the dust strip in the dust seal body 1 12, an annular sealed space S <b> 3 is defined, and the tip of the oil lip 13 is in close contact with the inner surface of the annular groove 113 opposite to the pressing plate 2.

  The presser plate 2 is provided with a pressure hole 22 extending in the radial direction and having an inner diameter end opened to the inner peripheral surface 2a. In other words, the inner diameter end of the pressure hole 22 is in the mounted state shown in FIG. In FIG. 2, an opening is formed in an annular sealed space S <b> 3 between the pressing plate 2 and the dust lip 12 in the dust seal main body 1, and the plug member 3 is provided at the outer diameter end of the pressure hole 22 opened on the outer peripheral surface of the pressing plate 2. Is attached.

  In the first embodiment, a grease nipple 3A is used as the plug member 3 as shown in FIG. The grease nipple 3A has a known structure, that is, is screwed into a female screw portion 22a formed at the outer diameter end of the pressurizing hole 22, and allows grease to be pressed in from outside by a grease gun (not shown). In addition, a check valve (not shown) for preventing the grease from flowing out in the opposite direction is incorporated. Note that reference numeral 23 in FIG. 3 is a hole for inserting a bolt for attaching the pressing plate 2 to the outer end portion of the cylinder 110.

  In the dust seal device 10 having the above configuration, the dust lip 12 of the dust seal body 1 has its inner peripheral edge closely contacted with the outer peripheral surface of the rod 120 so as to be slidable with an appropriate tightening margin. The oil lip 13 is in close contact with the outer peripheral surface of the rod 120 so as to be slidable with an appropriate tightening allowance, so that oil leakage from the rod seal 210 side is further reduced to the external space. This prevents leakage to the S2 side.

  And, when the tightening margin of the dust strip 12 with respect to the outer peripheral surface of the rod 120 is lowered due to aging or the like over time, the sealing performance against muddy water and dust is impaired accordingly. A grease gun (not shown) is applied to the grease nipple 3A, and as shown in FIG. 4, an annular sealed space between the press plate 2 and the dust strip 12 in the dust seal body 1 through the pressure hole 22 from the grease nipple 3A. If the grease G is press-fitted and filled in S3, the pressure of the grease G in the sealed space S3 acts to increase the tightening margin of the dust lip 12, and the check valve and presser built in the grease nipple 3A are pressed. Grease G is confined between dust strip 12 which is in close contact with inward projecting edge 21 of plate 2 with an appropriate margin, and the pressure is maintained. Runode, excellent sealing of the dust lip 12 is maintained against mud and dust.

  Further, according to the above configuration, the holding plate 2 that prevents the dust seal main body 1 from coming off the annular groove 113 forms a sealed space S3 for increasing the surface pressure of the dust lip 12 with respect to the outer peripheral surface of the rod 120. It also serves as a supply path for the grease G to the sealed space S3, and the grease nipple 3A that is the supply port of the grease G has a function as a plug member 3 that holds the pressure of the grease G in the sealed space S3. It can be a simple structure.

  FIG. 5 shows a second embodiment of the dust seal device according to the present invention. In this embodiment, a bolt 3B that is screwed into a female screw portion 22a formed in the pressure hole 22 of the pressing plate 2 is employed as the plug member 3 in place of the grease nipple 3A in the first embodiment described above. It is what. Further, a locking nut 31 is attached to the bolt 3B at the outer peripheral side of the presser plate 2. Other configurations can be configured in the same manner as in the first embodiment.

  The operation according to the second embodiment will be described with reference to FIG. 4 showing a portion common to the first embodiment. For example, the pressurizing hole 22 of the presser plate 2 and the sealed space S3 communicating with the presser plate 2 in advance. In addition, grease G is sealed in, and the bolt 3B is attached to the female screw portion 22a of the pressurizing hole 22 and fixed by the locking nut 31, and the tightening margin of the dust lip 12 with respect to the outer peripheral surface of the rod 120 is changed over time. If the bolt 3B is fixed due to looseness or the like, the bolt 3B is released from the locking nut 31 and then the bolt 3B is screwed into the female screw portion 22a. The grease G inside is press-fitted into the sealed space S3, and the pressure acts to increase the tightening margin of the dust lip 12, and the bolt 3B is fixed with the locking nut 31. Since the pressure of the grease G is maintained, excellent sealing performance of the dust lip 12 against the muddy water and dust is maintained.

  Note that the grease G may be filled when it becomes necessary to recover the tightening margin of the dust lip 12.

  FIG. 6 shows a third embodiment of the dust seal device according to the present invention, and FIG. 7 shows a fourth embodiment.

  Among these, the third embodiment shown in FIG. 6 is an O-ring 24 that is in close contact with the tip of the dust lip 12 in the dust seal body 1 in an annular groove formed on the inner surface of the inwardly protruding edge 21 of the pressing plate 2. Is provided. The O-ring 24 corresponds to the sealing means described in claim 5. If comprised in this way, the leak of the grease press-fitted and filled in the sealed space S3 between the pressing plate 2 and the dust lip 12 can be reliably prevented, and the tightening margin of the dust lip 12 can be maintained for a long time. .

  In the fourth embodiment shown in FIG. 7, the inner surface of the inward protruding edge 21 of the pressing plate 2 is engaged with a groove-shaped step portion 12 a formed at the tip of the dust lip 12 in the dust seal body 1. The seal protrusion 21a that is brought into close contact with the state is formed. The sealing protrusion 21a corresponds to the sealing means described in claim 5. Also in this case, leakage of the grease press-fitted and filled in the sealed space S3 between the pressing plate 2 and the dust strip 12 can be reliably prevented, and the tightening margin of the dust strip 12 can be maintained for a long time.

  Note that the third embodiment shown in FIG. 6 and the fourth embodiment shown in FIG. 7 are both the grease nipple 3A or the bolt 3B described above as the plug member 3 attached to the pressure hole 22. A locking nut 31 can be employed.

  Note that the dust strip with a shaft diameter of φ40, initial compression force = 233N, and initial maximum surface pressure = 12.6 MPa was completely lost to allow tightening force = 0N and maximum surface pressure = 0 MPa. FEM analysis was performed when grease pressure was applied from the outer periphery, and when the grease pressure was 1 MPa, the tension was restored to 184 N and the maximum surface pressure was restored to 9.3 MPa, and when the grease pressure was 2 MPa, the tension was 263 N and the maximum surface pressure was Was recovered to 10.2 MPa.

DESCRIPTION OF SYMBOLS 1 Dust seal body 12 Dustrip 2 Holding plate 21 Inward protruding edge 21a Seal protrusion (seal means)
22 Pressurizing hole 24 O-ring (sealing means)
3 Plug member 3A Grease nipple 3B Bolt 31 Locking nut 110 Cylinder (outer peripheral body)
113 annular groove 120 rod (inner peripheral member)
S1 Oil chamber S2 External space S3 Sealed space

Claims (5)

  A dust seal main body is provided in an annular groove formed on the inner peripheral surface of the outer peripheral member, and the dust seal main body slides on the outer peripheral surface of the inner peripheral member inserted into the inner periphery of the outer peripheral member so as to be axially movable. A dust lip is provided that is movably brought into close contact with a tip end that is in close contact with the inner surface of the annular groove, and grease that can be press-fitted into the sealed space between the dust lip and the annular groove on the outer peripheral member. A dust seal device in which a pressure hole is formed, and a plug member for holding the grease pressure in the sealed space is attached to the pressure hole.   The outer peripheral member comprises an outer peripheral member main body and a pressing plate attached to an end of the outer peripheral member main body, and an annular groove for mounting the dust seal main body is formed between the outer peripheral member main body and the pressing plate, and the tip of the dust lip of the dust seal main body The dust seal device according to claim 1, wherein an inner surface of an annular groove to which a portion is in close contact is formed in the pressing plate, and a pressure hole is formed in the pressing plate.   The dust seal device according to claim 1 or 2, wherein the plug member comprises a grease nipple that allows the grease to be injected from the outside and prevents the grease from flowing out to the outside.   The dust seal device according to claim 1 or 2, wherein the plug member comprises a bolt screwed into the pressure hole.   The dust seal device according to any one of claims 1 to 4, wherein a sealing means is provided on the inner surface of the annular groove to which the tip of the dust lip is in close contact.

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