Dust seal

Abstract

To provide a dust seal which has dust-resistant performance for preventing the intrusion of foreign matter and lubrication-retaining performance for retaining a liquid lubricant, and which is easy to configure and install with a small number of members. [Solution] A dust seal (20) is present on a sliding surface (12a) between a first relative moving member (housing) (11) and a second relative moving member (rod) (12), and the dust seal comprises an annular first seal portion (21) made of an elastic material and having a lip portion (21a), an annular second seal portion (22) having a nonwoven fabric structure and including a resin fiber bundle assembly (26) in which bundles (24) of a plurality of bundled resin fibers (23) are entangled to form a three-dimensional communicating space (29), and vulcanized bond reinforced portions (28) made of a vulcanized rubber elastic body that partially bond the bundles, and which comes into surface contact with the sliding surface (12a). The first seal portion (21) has a storage portion (21-2) inside the first relative moving member (11) that can store the second seal portion (22), and the first and second seal portions are integrated.

Description

[Technical Field]

[0001] This invention relates to a dust seal that is attached to reciprocating equipment such as hydraulic cylinders and fluid pressure cylinders used in pneumatic equipment and water hydraulic equipment. [Background technology]

[0002] In reciprocating motion devices such as hydraulic cylinders and fluid pressure cylinders, a dust seal is usually installed between the reciprocating rod and the housing that houses the rod to prevent the intrusion of foreign matter such as liquid or dust. Hereinafter, the housing will be referred to as the first relative moving member, and the rod will be referred to as the second relative moving member.

[0003] The dust seal is an annular component that includes a metal reinforcing ring and a sealing portion that covers the entire reinforcing ring. The dust seal is housed in a mounting groove cut into the inner circumferential surface of the housing or the outer circumferential surface of the rod, and is fixed so as to be in contact with the reciprocating rod or housing.

[0004] Cylinders (reciprocating equipment) are often used in harsh environments, such as under high pressure. Furthermore, as the number of reciprocating movements of the rod increases, the sliding surfaces of the dust seal wear out due to the sliding of the rod and housing. When the dust seal wears out, liquids and dust get into the housing, reducing the efficiency of the cylinder. For this reason, dust seals with high sealing ability and excellent durability have been disclosed (for example, Japanese Patent Application Laid-Open Nos. 2006-226455 and 2006-170341).

[0005] Japanese Patent Application Laid-Open Publication No. 2006-226455 discloses a dust seal (scraper) equipped with an annular first seal portion, a second seal portion, an annular packing, and a backup ring. The first seal portion and the second seal portion are arranged in order from the atmosphere side (exterior of the housing and rod), with the annular packing and backup ring spaced apart from the first and second seal portions. The second seal portion is attached inside the first seal portion so as to be in surface contact with the outer circumferential surface of the rod. The first seal portion is an annular member made of an elastic material, and the second seal portion is an annular member made of a resin material. Both the first seal portion and the second seal portion have a lip portion that contacts the sliding surface of the rod. The backup ring is located directly below the packing and holds the packing in place.

[0006] Japanese Patent Application Laid-Open Publication No. 2006-170341 discloses a fibrous wiper member having a nonwoven structure, a resin fiber bundle assembly in which bundles of multiple resin fibers are entangled to form a three-dimensional interconnected space, and vulcanized bond reinforced portions made of vulcanized rubber elastic material that partially connects each of the bundles. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-226455 [Patent Document 2] Japanese Patent Application Laid-Open No. 2006-170341 Summary of the Invention [Problem to be solved by the invention]

[0008] In JP 2006-226455 A, the first and second seal portions each have a lip portion, and even if the lip portion of the first seal portion is unable to completely remove foreign matter, the lip portion of the second seal portion provided inside the first seal portion can catch it.

[0009] The dust seal of JP 2006-226455 A further includes an annular packing and a backup ring at positions spaced apart from the first and second seal portions. The addition of the annular packing and backup ring further prevents foreign matter such as liquid and dust from entering the dust seal from outside. However, the dust seal has a large number of components, making the overall structure complex. Furthermore, the inner surface of the housing must be provided with mounting grooves into which each component, such as the first seal, second seal, packing, and backup ring, can be inserted and installed. Even slight differences in the size of the grooves prevent the components from fitting together, creating gaps. In this case, components may become detached due to being unable to withstand the reciprocating motion of the rod, or foreign matter may become trapped inside.

[0010] In particular, the second seal must be fitted tightly to the inside of the first seal. Furthermore, the first and second seals are made of an elastic material and a resin material, respectively, making it difficult to accurately pre-form the shapes of the first and second seals. Furthermore, because the first and second seals and other components come into contact with the rod during reciprocating motion, deformation and wear are unavoidable.

[0011] The fibrous wiping member disclosed in JP 2006-170341 A can hold a liquid lubricant in a three-dimensional space. If the liquid lubricant is held in the wiping member, deformation and wear of the member can be prevented to a certain extent. However, the wiper ring is made of a fibrous, soft material and does not have a consistent shape. Therefore, the wiper ring cannot withstand the reciprocating motion of the rod and may become twisted and deformed, which may allow foreign matter to enter the wiper ring. In addition, a mounting groove for fitting the wiper ring without any gaps must be accurately formed in advance on the inner circumferential surface of the housing. The wiper ring is a small component, and it is not easy to form a mounting groove that matches its shape in advance. Furthermore, when fitting the wiper ring, the small, soft wiper ring must be temporarily compressed before being fitted into the mounting groove on the inner circumferential surface of the housing. This type of fitting operation is delicate and not easy.

[0012] The purpose of this invention is to provide a dust seal that can withstand the reciprocating motion of a rod by preventing the intrusion of foreign matter and preventing deformation and wear of the components, and that is easy to construct and install with few components. [Means for solving the problem]

[0013] To achieve the above object, the present invention combines a first sealing portion having a lip portion with a second sealing portion having a nonwoven fabric structure. That is, according to the present invention of claim 1, there is provided a dust seal located on a sliding surface between a first relative moving member and a second relative moving member that is inserted inside the first relative moving member and moves axially of the first relative moving member while sliding relative to the first relative moving member, the dust seal comprising: an annular first seal portion made of an elastic material having a lip portion; a resin fiber bundle assembly having a nonwoven fabric structure in which bundles of a plurality of resin fibers are entangled to form a three-dimensional communicating space; and an annular second seal portion that is in surface contact with the sliding surface, the first seal portion having a storage portion inside the first relative moving member that can store the second seal portion, and the second seal portion being in contact with the contact surface of the second relative moving member. [Effects of the Invention]

[0014] In the present invention according to claim 1, the first and second seals can prevent the intrusion of foreign matter with fewer components. The second seal is housed in the housing of the first seal and is integrated with it, making it easy to configure and install the dust seal. Furthermore, because the second seal is housed in the housing of the first seal and its shape is maintained, there is no risk of the components being deformed by the reciprocating motion of the rod (second relative moving member). A liquid lubricant can be held in the three-dimensional communicating space of the second seal portion, thereby preventing wear of the components. [Brief explanation of the drawings]

[0015] [Figure 1] 1A and 1B are cross-sectional views of a dust seal according to an embodiment of the present invention and first and second relative moving members to which the dust seal is attached, and a partially enlarged view showing the configuration of the second seal portion. [Figure 2] 1 is a cross-sectional view of a dust seal (first and second seal portions) according to an embodiment of the present invention. [Figure 3] (A) shows a schematic diagram of the experiment to confirm the dust resistance performance of the dust seal, and (B) shows a schematic diagram of each sample (dust seal, etc.). [Figure 4] 10 is a diagram showing the results of an experiment to confirm the dust resistance performance of the dust seal. FIG. [Figure 5] FIG. 1 is a schematic diagram of an experiment to confirm the lubrication retention performance of a dust seal. DETAILED DESCRIPTION OF THE INVENTION

[0016] a dust seal disposed on a sliding surface between a first relative moving member and a second relative moving member that is inserted inside the first relative moving member and moves relatively in the axial direction of the first relative moving member while sliding, the dust seal comprising: an annular first seal portion made of an elastic material having a lip portion; a resin fiber bundle assembly having a nonwoven fabric structure, the resin fiber bundle assembly having a three-dimensional communicating space formed by entangling bundles of a plurality of resin fibers; and an annular second seal portion that comes into surface contact with the sliding surface, the first seal portion having a storage portion inside the first relative moving member that can store the second seal portion, the second seal portion coming into contact with the contact surface of the second relative moving member; [Example]

[0017] An embodiment of the present invention will be described in detail below with reference to the drawings. Figure 1 is a cross-sectional view of a dust seal according to an embodiment of the present invention and first and second relative moving members to which the dust seal is attached, and a partially enlarged view showing the configuration of the second seal portion. Figure 2 is a cross-sectional view of the dust seal (first and second seal portions) according to an embodiment of the present invention.

[0018] A reciprocating device 10 used in pneumatic equipment, hydraulic equipment, etc., is configured with a first relative moving member 11 made of, for example, a housing, and a second relative moving member 12 made of a rod. The second relative moving member (rod) 12 is inserted inside the first relative moving member (housing) 11 and moves relatively in the axial direction of the first relative moving member (the direction of the arrow in FIG. 1) while sliding. Reference numeral 12a denotes the sliding surface of the second relative moving member 12 that comes into contact with the first relative moving member 11.

[0019] A lubricating film (not shown) of a liquid lubricant such as water, oil, or liquid grease is formed on the sliding surface 12a. Liquids such as water and dust that are mixed in from the atmosphere side A outside the housing 11 may be present on or near the surface of the lubricating film (not shown). Foreign matter B may be, but is not limited to, these. An attachment groove 11-1 is formed on the inner circumferential surface of the first relative moving member (housing), and a dust seal 20 is built in and fixed inside the attachment groove 11-1.

[0020] The dust seal 20 includes a first seal portion 21 and a second seal portion 22. As can be seen from Fig. 1, the dust seal 20 is arranged in the axial direction of the first relative moving member (housing) 11 from the atmosphere side A (see Fig. 1) outside the housing 11, with the first seal portion 21 and the second seal portion 22 arranged in this order. The outside of the first seal portion 21 faces the atmosphere side A.

[0021] The first seal portion 21 is an annular member made of an elastic material. Specifically, the first seal portion 21 is formed by coating the periphery of a circular reinforcing ring 21-1 having an L-shaped or J-shaped cross section with an elastic material such as synthetic rubber or synthetic resin. The first seal portion 21 mainly prevents dust from entering from the outside, protecting the interior of the first relative movement member (housing) 11 and the second relative movement member (rod) 12. A storage section 21-2 capable of storing the second seal section 22 is formed inside the first seal section 21, away from the atmosphere side A. When the second seal section 22 is stored in the storage section 21-2 of the first seal section, the first and second seal sections are integrated to form the dust seal 20, which is then attached to and fixed in the attachment groove 11-1 of the housing. Note that the reference numeral 21-3 in FIG. 2 denotes a stepped portion of the first seal section 21 that covers the reinforcing ring 21-1.

[0022] The first seal portion 21 has a lip portion 21a formed at its end on the atmosphere side A, which comes into contact with the second relative moving member (rod) 12. As shown in FIG. 1, the lip portion 21a protrudes from the inner circumference of the annular first seal portion 21 to form an interference, and is in elastically close contact with the second relative moving member (rod) 12. The symbol δ in FIG. 2 indicates the interference of the lip portion 21a. Because the first seal portion 21, including the lip portion 21a, is made of an elastic material and the lip portion has a slight interference δ, the lip portion can be elastically biased against the outer circumferential surface of the second relative moving member (rod) 12 and come into close contact. In addition, the symbol φd in Figure 2 indicates the inner diameter (diameter) of the first seal portion 21, φD indicates the outer diameter (diameter) of the first seal portion, H indicates the overall height of the first seal portion, and h indicates the height of the step portion 21-3 that covers the reinforcing ring 21-1.

[0023] The second seal portion 22 is an annular member made of a nonwoven fabric structure and in surface contact with the sliding surface 12a of the second relative moving member (rod). In Fig. 2, the symbol φd' denotes the inner diameter (diameter) of the second seal portion 22, φD' denotes the outer diameter (diameter) of the second seal portion, and t denotes the height of the second seal portion. The configuration of the second seal portion 22 is similar to that of the wiper member disclosed in Japanese Patent Application Laid-Open No. 2006-170341 by the present applicant. As shown in the enlarged view of the double-dashed line portion in Fig. 1, the second seal portion 22 generally includes a resin fiber bundle assembly 26 in which a large number of bundles 24 each consisting of a plurality of resin fibers 23 are entangled to form a three-dimensional interconnected space, and vulcanized bond-reinforced portions 28 made of a vulcanized rubber elastic material that partially connect each of the many bundles. That is, the second seal portion 22 has a nonwoven fabric structure having a basic skeleton of a resin fiber bundle assembly in which a large number of bundles 24 each consisting of a plurality of resin fibers 23 are entangled, and vulcanized bond-reinforced portions 28 made of a vulcanized rubber elastic material that partially connect each of the many bundles 24, thereby continuously forming a three-dimensional interconnected space 29 in a network-like pattern within the second seal portion 22.

[0024] The communication space 29 can hold and pass a liquid lubricant (not shown) that constitutes the lubricating film, and can supply the held liquid lubricant to the sliding surface 12a by capillary action.

[0025] In this example, experiments were conducted under the conditions described below to confirm (1) the dust resistance performance of the dust seal according to the present invention, and (2) the lubrication retention performance of the dust seal, particularly the second seal portion 22. For each experiment, the installation of the dust seal 20 will be described. First, the second seal portion 22 is housed and integrated into the housing portion 21-2 of the first seal portion to form the dust seal 20. The dust seal 20 is built into and fixed inside the mounting groove 11-1 of the first relative moving member (housing).

[0026] (1) Dust resistance Figure 3(A) shows a schematic diagram of the experiment to confirm the dust resistance performance of the dust seal, and (B) shows a schematic diagram of each sample (dust seal, etc.). Experiments were conducted and compared on two specimens: (a) a specimen with only the first seal portion 21 attached to the inner circumferential surface of the housing (first relative moving member) 11 of a vertical dust testing device (triple dust testing machine) with a rod diameter of 45 mm, and (b) a specimen with a dust seal 20 equipped with the first and second seal portions 21 and 22 attached to the inner circumferential surface of the housing (first relative moving member) 11 of the vertical dust testing device (triple dust testing machine) with a rod diameter of 45 mm. Naturally, the same first seal portion 21 was used in both experiments. The dimensions of the first and second seal portions 21 and 22 are as shown in Table 1. The second seal 22 was also impregnated with grease (not shown) as a liquid lubricant.

[0027] [Table 1]

[0028] As shown in Figure 3(A), Kanto Loam Type 7 was used as the test medium. In this experiment, Kanto Loam Type 7 refers to the test powder specified in JIS Z 8901, which is composed mainly of SiO2 (silica), Fe2O3 (iron oxide), and Al2O3 (aluminum oxide), and is made by calcining Kanto volcanic ash soil and adjusting the particle size distribution. The stroke of the rod (second relative moving member) 12 was 300 mm, the cycle was 30 cpm, and the number of reciprocating movements (endurance) was 10,000. The temperature during the experiment was room temperature (natural heat generation). In addition, dust collection paper and dust collection packing were used separately for the experiment (Figure 3).

[0029] Figure 4 shows the results of an experiment to confirm the dust resistance of the dust seal. As shown in the "Amount of Dust Penetration" and "Appearance" sections of Figure 4, when only the first seal portion 21 is used, dust contamination is visible on the inner circumferential surface of the housing (first relative moving member) 11. As shown in the "Amount of Dust Penetration" and "Appearance" sections of Figure 4, when the dust seal 20 includes the first and second seal portions 21 and 22, dust is barely visible on the inner circumferential surface of the housing (first relative moving member) 11. This shows that the dust seal 20 of the present invention has better dust resistance than the first seal portion 21 alone.

[0030] (2) Lubrication retention performance FIG. 5 is a schematic diagram of an experiment to confirm the lubrication retention performance of the dust seal. As in experiment (1), in experiment (2), two samples were tested and compared: (a) a sample with only the first seal portion 21 attached to the inner circumferential surface of the housing (first relative moving member) 11 of a vertical dust test device with a rod diameter of 45 mm; and (b) a sample with a dust seal 20 equipped with the first and second seal portions 21 and 22 attached to the inner circumferential surface of the housing (first relative moving member) 11 of a vertical dust test device with a rod diameter of 45 mm. The dimensions of the first and second seal portions 21 and 22 were the same as in experiment (1) (Table 1). The second seal portion 22 was also impregnated with grease (not shown). As shown in Figure 5, the experimental conditions (stroke, cycle, temperature) were the same as those in experiment (1). In experiment (2), a thin layer of grease (approximately 0.03 g) was applied to the tip of the lip portion 21a of the first seal. In addition, the surface of the rod (second relative moving member) 12 was wiped and degreased with a separately prepared parts cleaner (see Figure 5) after each reciprocation.

[0031] The results of the experiment are shown in Table 2. As shown in the "Rod surface temperature" column in Table 2, in the case of only the first seal portion 21, the surface temperature of the rod 12 was 28.5°C after 500 durability cycles and 35.5°C after 1000 cycles. Furthermore, it was confirmed that abnormal noise was generated due to contact between the first seal portion 21 and the rod 12 after approximately 600 cycles. On the other hand, in the case of the dust seal 20 having the first and second seal portions 21 and 22, the surface temperature of the rod 12 was 24.9°C after 500 durability cycles and 26.4°C after 1000 cycles. Furthermore, no abnormal noise was confirmed. This shows that the second seal portion 22 of the dust seal of the present invention prevents the rod surface from becoming too hot. Also, since no abnormal noise is generated, it can be seen that the dust seal 20 of the present invention has better lubrication retention performance than the first seal portion 21 alone.

[0032] [Table 2]

[0033] The dust seal 20 is configured with first and second seal portions 21 and 22, and can prevent the intrusion of foreign matter with a small number of components. The second seal portion 22 is made of a soft material, so it can be easily fitted and stored in the storage portion 21-2 of the first seal portion. This makes the dust seal 20 easy to configure and install. The lip portion 21a of the first seal portion, formed from an elastic material, is flexible, so it goes without saying that it can remove foreign matter B adhering to the surface of the rod 12. Although the second seal portion 22 is made of a soft material, it is housed in the housing portion 21-2 of the first seal portion and its shape is maintained, so there is no risk of it being twisted or deformed by the reciprocating motion of the rod 12. Furthermore, the dust seal 20 can be simply attached and fixed in the mounting groove 11-1, which also simplifies the construction and assembly of the dust seal.

[0034] As in JP 2006-170341 A, the second seal portion 22 has a three-dimensional communicating space 29, which allows the liquid lubricant to be retained in that space. Therefore, the liquid lubricant can be supplied to the sliding surface 12a by capillary action. Furthermore, during the reciprocating motion of the rod 12, excess liquid lubricant on the sliding surface 12a is absorbed by the communicating space 29 and the gaps between the bundled resin fibers 23, and then resupplied to the sliding surface 12a. Therefore, providing the second seal portion 22 to the first seal portion 21 improves dust resistance and lubricant retention. In the experiment, the term "(1) dust resistance" was used, but since Kanto loam actually contains not only foreign matter such as dust but also liquids such as water, it goes without saying that the first and second sealing portions 21, 22 can also prevent the intrusion of liquids.

[0035] The above-described embodiments are intended to explain the present invention and are not intended to limit the present invention in any way. It goes without saying that all modifications and alterations within the technical scope of the present invention are also encompassed by the present invention. For example, although the dust seal is attached to the inner peripheral surface of the housing in the embodiment, it may also be attached to the outer peripheral surface of the rod. [Industrial Applicability]

[0036] This invention can be widely applied to various cylinders (reciprocating devices). [Explanation of symbols]

[0037] 10 Cylinders (reciprocating motion devices) 11 housing (first relative moving member) 11-1 Mounting groove 12 Rod (second relative moving member) 12a Sliding surface 20 Dust seal 21 First seal part 21-1 Reinforcement ring 21-2 Storage area 22 Second seal part

Claims

[Claim 1] a dust seal disposed on a sliding surface between a first relative moving member and a second relative moving member that is inserted into the first relative moving member and moves relatively in an axial direction of the first relative moving member while sliding, The dust seal is an annular first seal portion made of an elastic material and having a lip portion; a resin fiber bundle assembly having a nonwoven fabric structure, in which a plurality of bundles of resin fibers are entangled to form a three-dimensional interconnected space, and a vulcanized bond reinforced portion made of a vulcanized rubber elastic body that partially bonds each of the bundles, and an annular second seal portion that is in surface contact with the sliding surface; The first seal portion has a storage portion capable of storing the second seal portion inside the first relative moving member, and the second seal portion is in contact with the contact surface of the second relative moving member.

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