JP5346595B2 - Dust seal and fluid pressure cylinder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dust seal which can prevent dust from coming with outside air and prevent inside working fluid from being scratched. <P>SOLUTION: A dust seal 5 is used for a seal between a cylinder body and a piston rod 12 of a fluid pressure cylinder used in a condition that it is exposed to the outside air and is arranged in a rod side end section of the cylinder body, wherein a dust embedding section 1a partially using a dust embedding resin as a material is integrally molded in its dust lip section 1. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a dust seal for sealing with outside air of a fluid pressure cylinder used for construction machinery and exposed to outside air, and a fluid pressure cylinder using the dust seal.

  In a hydraulic cylinder used for construction machinery and exposed to the outside air, between the cylinder body of the fluid pressure cylinder and the piston rod, the rod side end of the cylinder body is used for sealing with the outside air. A dust seal is installed to prevent the intrusion of dust including water and sand particles from the outside air.

  However, even if a dust seal is provided, dust may still enter, and in that case, the intruded dust may damage the rod, dust seal, and various internal seals, and fluid leakage to the outside Has been generated.

  Conventionally, the cause of this dust intrusion was thought to be a gap larger than the dust between the dust seal and the piston rod generated due to the lateral blur of the piston rod. The reason is thought to be that dust intrudes beyond the contact area between the dust lip and the piston rod.

  FIG. 6 is a diagram for explaining the cause of the dust intrusion. In FIG. 6, reference numeral 42 denotes a piston rod, reference numeral 31 denotes a dust lip of a dust seal 35 provided at a rod side end of a cylinder body of a hydraulic cylinder, Symbol D is dust (assuming a hard material such as sand particles).

  Here, in general, in order to prevent dust from entering, if the edge radius of the dust strip 31 where the dust seal 35 is in contact with the piston rod 42 is reduced, smaller dust D can be eliminated. The working fluid is scraped out, so that it cannot be made very small, and there is a limit to preventing dust intrusion at the edge radius of the dust lip, as shown in FIGS. 6 (a) and 6 (b). Intrusion could not be completely prevented.

  On the other hand, there are those described in Patent Documents 1 to 7 for dust seals for fluid pressure cylinders, etc., all of which are analyzed by analyzing the cause of dust intrusion from the outside air as described above. It was not a solution issue.

Japanese Utility Model Publication No. 61-58767 (reference numeral 6 in FIG. 3) Japanese Utility Model Publication No. 63-185964 (FIGS. 1 to 4) JP 2000-74223 A (reference numeral 11 in FIG. 2) Japanese Patent Laying-Open No. 2004-19866 (reference numeral 16 in FIG. 2) Japanese Patent Laying-Open No. 2005-265161 (reference numeral 20 in FIG. 1) Japanese Patent Laying-Open No. 2006-29518 (reference numeral 11 in FIG. 3) Japanese Patent Laying-Open No. 2008-223900 (reference numerals 10 and 20 in FIG. 1)

  The present invention is intended to improve the above-mentioned problem. A dust seal capable of preventing dust from entering from outside air and preventing the working fluid from being scraped out, and a fluid pressure cylinder using the dust seal are provided. Providing is a solution issue.

The dust seal of the present invention is a dust seal used for a seal between a cylinder body and a piston rod of a fluid pressure cylinder used in a state exposed to outside air, and is installed at a rod side end of the cylinder body. A dust buried portion made of a dust buried resin is partially formed integrally with the dust lip portion so as to surround the piston rod over the entire circumference of the dust buried portion, and the dust buried portion is formed in a ring shape or It is a sheet shape .

  The fluid pressure cylinder of the present invention is used in a state exposed to the outside air, and the dust seal of the present invention is installed at the rod side end of the cylinder body.

According to the dust seal of the present invention, a dust seal used for a seal between a cylinder main body and a piston rod of a fluid pressure cylinder used in a state exposed to outside air, which is installed at a rod side end of the cylinder main body. A dust buried portion made of a dust buried resin is partially formed integrally with the dust wrap portion so as to surround the piston rod over the entire circumference of the dust buried portion, and the dust buried portion is a ring. Since it has a shape or a sheet shape, it is possible to prevent dust from entering from the outside air of the dust lip and to prevent the working fluid from being scraped out.

  The fluid pressure cylinder of the present invention is used in a state exposed to the outside air. Since the dust seal of the present invention is installed at the rod side end of the cylinder body, the effect of the dust seal is exhibited as a fluid pressure cylinder. .

An example of the dust seal | sticker of this invention is shown, (a) is principal part sectional drawing of the use condition, (b) is sectional drawing which shows the state which buried the dust in (a). The other example of the dust seal | sticker of this invention is shown, (a) is principal part sectional drawing of the use condition, (b) is sectional drawing which shows the state which buried the dust in (a). The other example of the dust seal | sticker of this invention is shown, (a) is principal part sectional drawing of the use condition, (b) is sectional drawing which shows the state which buried the dust in (a). The other example of the dust seal | sticker of this invention is shown, (a) is principal part sectional drawing of the use condition, (b) is sectional drawing which shows the state which buried the dust in (a). The hydraulic cylinder using the dust seal of this invention is shown, (a) is the principal part longitudinal cross-sectional view, (b) is an expanded sectional view of the seal part of (a). An example of the dust seal which is the background art of this invention is shown, (a) is a principal part sectional drawing of the use condition, (b) is sectional drawing which shows the state which passed the dust inside in (a).

  Embodiments of the present invention will be described below with reference to the drawings.

Embodiment 1

  FIG. 1 shows an example of the dust seal of the present invention, in which (a) is a cross-sectional view of the main part of the used state, and (b) is a cross-sectional view showing a state where dust is buried in (a).

  The dust seal 5 is a dust seal 5 used for sealing between a cylinder body and a piston rod 12 of a fluid pressure cylinder (see FIG. 4) used in a state exposed to the outside air. The dust burial portion 1a is made of a dust burying resin as a raw material and is integrally formed on the dust lip portion 1 of the dust strip portion 1 at the rod side end.

  Specifically, in this dust seal 5, the dust buried resin is TPE (thermoplastic elastomer), and the dust buried portion 1 a constitutes the outside air side of the dust strip portion 1 as shown in FIG. 1. In the ring shape, it reaches the contact portion with the piston rod 12 and the dust lip portion 1 is in contact with the piston rod 12 inside the dust buried portion 1a.

  The present applicant has found that TPE includes those having characteristics of burying fine hard dust such as sand grains, and by using these characteristics, the edge portion of the dust strip portion 1 can be completely excluded. As shown in FIG. 1 (b), dust D does not enter the cylinder, and the piston rod 12 and various seals inside are buried. It has been found that it can be done without hurting.

  In addition, since dust is buried in the dust buried portion 1a reaching the contact portion of the dust lip portion 1 with the piston rod 12, the edge radius of the dust lip portion 1 is more than necessary in consideration of dust removal. Therefore, the problem of scraping out the working fluid inside can be solved.

  That is, according to this dust seal 5, it is possible to prevent dust from entering from the outside air and to prevent the internal fluid from being scraped out.

  Moreover, according to this dust seal 5, since a different material is used for the dust buried part 1a which is a part of the dust lip 1, only this dust buried part 1a can be made into a different color, The appearance of the dust seal 5 can be differentiated and appealed to customers.

  Further, according to the dust seal 5, the dust buried portion 1a is integrated with the dust lip 1, that is, with the dust seal 5 by two-color injection molding, which is one of integral molding. There is no need for parts, and there is no need for a space or work process for separately installing parts for dust burial.

  More specifically, the dust seal 5 has a main body portion (a portion other than the dust buried portion 1a) made of UR (urethane rubber), and the dust buried portion 1a made of TPU (thermoplastic polyurethane) which is a kind of TPE. As described above, as described above, both are integrated by two-color injection molding.

  Here, as an integral molding method of resin molding in an oil seal as in the present invention, a dust buried portion which is a separate member is first molded into a certain shape, and the dust buried portion after molding is oil-sealed. -Insert (insert) into the target position or part of the mold, and then insert the resin on the main body side to mold the whole, and the resin of a different material at each position or part. There is the above-described two-color injection molding method in which injection is performed before and after.

  As in the oil seal 5 of the first embodiment, when the main body side is UR, and the dust buried portion 1a is a ring shape (a disk shape forming an outer portion of the oil seal) made of TPU, the above-mentioned As described above, two-color injection molding is suitable.

  In addition, in the oil seal 5, the dust buried portion 1 a is not limited and reaches to a position near the contact portion between the oil seal 5 and the piston rod 12 to bury the dust D. Since the oil seal 5 is in contact, the advantages of the oil seal made of UR that are excellent in wear resistance, high hardness, high elasticity, impact resistance, oil resistance, and difficult to pass are maintained.

  If the ring-shaped dust buried portion 1a is to be insert-molded like the oil seal 5, machining is required to pre-form the ring shape of the dust buried portion, which increases the cost. However, if the cost problem is excluded, the oil seal 5 can be manufactured by insert molding.

  Furthermore, in the oil seal 5 having the ring-shaped dust buried portion 1a, the volume of the dust buried portion 1a is large and the amount of resin used is large, but also in this respect, the TPE (TPU) whose unit price is relatively low ) Is suitable.

  On the other hand, in this type of dust seal, PTFE (polytetrafluoroethylene) may be used as the dust burying resin. PTFE has a problem that the material itself is expensive and a problem that the molding cost before the insert molding is relatively expensive. However, these problems are caused by the use of PTFE as a dust burying resin. It is not excluded.

  In addition, although the technique of comprising a part or all of a dust seal or an oil seal by PTFE is described in Patent Document 2 and Patent Document 3, these use the low friction property of PTFE. There is no description about dust burying property in literature.

  Moreover, although the technique of absorbing and burying the fine powder inside a hydraulic cylinder with an internal dust seal is described in Patent Document 1, this technique does not prevent the intrusion of dust from the outside air. It requires an internal dust seal, which is a separate and independent part, for absorption and therefore requires extra space.

  Moreover, about the internal dust seal of this patent document 1, there is no description about a specific raw material, and there is no description about PTFE.

Embodiment 2

  2A and 2B show another example of the dust seal of the present invention, in which FIG. 2A is a cross-sectional view of a main part of the used state, and FIG. 2B is a cross-sectional view showing a state where dust is buried in FIG. Accordingly, the same parts as those already described may be denoted by the same reference numerals and redundant description may be omitted.

  The dust seal 5A is a sheet shape in which the dust burying resin is PTFE, and the dust burying portion 1b covers the contact portion with the piston rod 12 of the dust lip portion 1 from the outside to the inside as shown in FIG. 1 and is different from the dust seal 5 of FIG. 1 in that the dust buried portion 1b is integrally formed by insert molding.

  In this case, since the contact portion with the piston rod 12 becomes the dust buried portion 1b, the dust D can be removed without making the edge radius smaller than the dust D as shown in FIGS. 2 (a) and 2 (b). It can be buried and captured, while scraping of the working fluid inside can be suppressed.

  That is, according to this dust seal 5A, as with the dust seal 5 of FIG. 1, it is possible to prevent dust from entering from the outside air and to prevent the internal fluid from being scraped out.

  Here, as described above, the inventor of the present application has found that PTFE can also be used as the dust burying resin. However, in the case of PTFE, there is a problem that the cost of the material is high. However, a sheet shape like the dust buried portion 1b of the dust seal 5A is advantageous because the amount of resin used can be reduced.

  In general, PTFE is difficult to mold. However, after forming a sheet that is generally easy to obtain and mold, it may be cut into a shape that covers the contact portion with the piston rod 12 of the dust strip 1 of the dust seal 5A. Therefore, if such a sheet-shaped dust buried portion 1b is used, the problems of formability before integral molding and the cost of the molding can be solved.

  As an integral molding method of the oil seal 5A in the case of such a sheet-shaped dust buried portion 1b, an insert molding method is suitable.

  As the dust embedding resin for this type of dust seal, TPE having dust embedding property including TPU proposed in the dust seal 5 of FIG. 1 may be adopted.

Embodiment 3

  3A and 3B show another example of the dust seal of the present invention, in which FIG. 3A is a cross-sectional view of a main part in the use state, and FIG. 3B is a cross-sectional view showing a state where dust is buried in FIG.

  In this dust seal 5B, the dust burying resin is TPE, and as shown in FIG. 3, the dust burying portion 1c forms a contact portion with the piston rod 12 of the dust lip portion 1 from the outside to the inside. The point which is a ring shape is different from the dust seal 5 of FIG.

  Also in this case, since the contact portion with the piston rod 12 becomes the dust buried portion 1c, the dust D can be removed without making the edge radius smaller than the dust D as shown in FIGS. 3 (a) and 3 (b). It can be buried and captured, while scraping of the working fluid inside can be suppressed.

  That is, according to the dust seal 5B, as in the dust seal 5 of FIG. 1, it is possible to prevent the intrusion of dust from the outside air and to prevent the internal fluid from being scraped out.

  Here, when the dust buried portion 1c is formed in a mountain-shaped ring shape that forms a contact portion with the piston rod 12 of the dust lip portion 1B as described above, as an integral molding method, the dust seal 1 of FIG. The two-color injection molding method is suitable similarly to the dust buried portion 1a, and the reason is the same.

  As the dust embedding resin for this type of dust seal, PTFE proposed in the dust seal 5A of FIG. 2 may be adopted in consideration of cost and moldability problems.

  The dust seal 5A in FIG. 2 and the dust seal 5B in FIG. 3 differ depending on whether the insert molding method or the two-color injection molding method is adopted as an integral molding method, but the dust buried portions 1b and 1c are different. It is common in the point that it is provided in the contact part with the piston rod 12 of the dust lip parts 1A and 1B from the outside air side to the inside side, and this seems to improve the dust burying property.

Embodiment 4

  4A and 4B show another example of the dust seal of the present invention, in which FIG. 4A is a cross-sectional view of a main part in the use state, and FIG. 4B is a cross-sectional view showing a state where dust is buried in FIG.

  As shown in FIG. 4, the dust seal 5C has a point that the dust embedding resin is PTFE and the dust embedding portion 1d has a sheet shape and is insert-molded as compared with the dust seal 5A of FIG. Although it is common, the dust buried portion 1d is only in the vicinity of the contact portion of the dust lip portion 1C from the outside to the inside with the piston rod 12 in contact with the piston rod 12. The difference is that it is on the main body side of the strip portion 1C.

  That is, this dust seal 5C is common to the dust seal 5A of FIG. 2 in terms of the material type of the dust-burying resin, the sheet shape, and the integral molding method, and the dust-buried portion 1d reaches the closest to the contact portion. However, it is the same as the dust seal 5 of FIG. 1 in that it does not contact the piston rod 12 and exhibits a dust burying function in close proximity.

  Therefore, according to the dust seal 5C, the effects of the dust seal 5 of FIG. 1 and the effects of the dust seal 5A of FIG.

  As the dust embedding resin for this type of dust seal, TPE having dust embedding property including TPU proposed in the dust seal 5 of FIG. 1 may be adopted.

Embodiment 5

  FIGS. 5A and 5B show a fluid pressure cylinder using the dust seal of the present invention, in which FIG. 5A is a longitudinal sectional view of an essential part thereof, and FIG. 5B is an enlarged sectional view of a seal portion of FIG.

  This fluid pressure cylinder is used as an actuator of a construction machine or a shock absorber of an automobile, and includes a piston 11, a piston rod 12 having the piston 11 at the tip, and the piston 11 and the piston rod 12 inside. A cylinder body 13 that is slid closely, and ports 15 and 14 that supply and discharge the working fluid provided above and below the cylinder body 13 are provided.

  The portion where the piston rod 12 protrudes to the outside air side, that is, the rod side end of the cylinder body 13 is provided with the second U-packing 7 and the backup member 8 provided with the dust seal 5 and the backup member 6 of FIG. A seal such as a first U-packing 9 is provided to prevent intrusion of dust from the outside air and prevent leakage of the working fluid inside.

  Although not shown, some rod side end portions of the cylinder body 13 are further provided with a bearing for the piston rod 12 inside.

  In this way, by providing the dust seal 5 of FIG. 1, the fluid pressure cylinder 20 exerts the effect of the dust seal 5 in addition to exerting the function of the normal fluid pressure cylinder 20. Can be demonstrated as.

  The fluid pressure cylinder may include the dust seals 5A to 5C of FIGS. 2 to 4 instead of the dust seal 5 of FIG. The effect of the dust seals 5A to 5C is exhibited as a fluid pressure cylinder.

  The dust seal and the fluid pressure cylinder of the present invention are not limited to the above-described embodiments, and various modifications and combinations are possible within the scope of the claims and the scope of the embodiments. Modifications and combinations are also included in the scope of the rights.

  The fluid pressure cylinder includes a hydraulic cylinder, a pneumatic cylinder, a hydraulic cylinder, and the like.

  The dust seal and fluid pressure cylinder of the present invention are used in industrial fields, particularly for construction machinery and various shock absorbers that are required to prevent dust from entering from the outside air and to prevent the working fluid from being scraped out. Can be used.

1-1C Dustrip part 1a-1d Dust buried part 5-5C Dust seal 12 Piston rod 13 Cylinder body 20 Fluid pressure cylinder

Claims (4)

A dust seal used for a seal between a cylinder body and a piston rod of a fluid pressure cylinder used in a state exposed to outside air,
It is installed on the rod side end of the cylinder body, and a dust buried portion made of dust buried resin is surrounded by a dust burying resin around the piston rod over the entire circumference of the dust buried portion. A dust seal , wherein the dust seal is integrally formed, and the dust buried portion has a ring shape or a sheet shape . The dust burying resin is TPE (thermoplastic elastomer) or PTFE (polytetrafluoroethylene), and the dust burying portion forms the outside air side of the dust lip portion, and comes close to the contact portion with the piston rod, dust seal according to claim 1, wherein the dust lip portion at the inner side of the dust buried portion is to contact the piston rod. 2. The dust seal according to claim 1, wherein the dust burying resin is PTFE or TPE, and the dust burying portion is provided at a contact portion with the piston rod of the dust lip portion from the outside air side to the inside side. A fluid pressure cylinder used in a state exposed to outside air, wherein the dust seal according to any one of claims 1 to 3 is installed at a rod side end of the cylinder body.

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