Rubber molded products and sealing devices

Abstract

This method effectively reduces deformation of the elastic portion while taking advantage of the flexibility and other properties of the rubber material. [Solution] The rubber molded product comprises an elastic portion having a first surface and a second surface opposite to the first surface, and is subjected to a load or external force such that, under normal use conditions, compressive stress is generated on the first surface and tensile stress is generated on the second surface, wherein the elastic portion comprises a rubber material and a sheet-like fibrous base material, and the fibrous base material is positioned closer to the first surface than to the second surface.

Description

Technical Field

[0006] , , , ,

[0001] The present disclosure relates to rubber molded products and sealing devices.

Background Art

[0002] In various industrial equipment, rubber molded products obtained by molding rubber materials are generally used for various parts that require flexibility. For example, in Patent Document 1, in a sealing device that seals an annular gap between two relatively rotating members, a seal member having a rubber-like elastic body is used.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In rubber molded products that receive a load or external force, when it is necessary to increase rigidity, generally, the hardness of the rubber used as the base material is increased, the wall thickness is increased, or it is adhered to a metal base material. However, in such rubber molded products, characteristics such as the flexibility of the rubber material are impaired. For example, in the seal member of Patent Document 1, when the rigidity is increased, there are problems such as excessive friction at the sliding portion and difficulty in deformation following movements such as vibration.

[0005] In view of the above circumstances, an object of the present disclosure is to provide a rubber molded product having an elastic portion with reduced deformation while utilizing characteristics such as the flexibility of the rubber material.

Means for Solving the Problems

[0006] To solve the above problems, a rubber molded article according to one aspect of the present disclosure comprises an elastic portion having a first surface and a second surface opposite to the first surface, and is subjected to a load or external force such that compressive stress is generated on the first surface and tensile stress is generated on the second surface under normal use conditions, wherein the elastic portion comprises a rubber material and a sheet-like fibrous base material, and the fibrous base material is positioned closer to the first surface than to the second surface.

[0007] A rubber molded article according to another aspect of the present disclosure comprises an elastic portion having a first surface which is an outer circumferential surface and a second surface which is an inner circumferential surface, and is subjected to a load or external force such that a greater tensile stress is generated in the circumferential direction on the second surface than on the first surface, wherein the elastic portion comprises a rubber material and a sheet-like fibrous base material, and the fibrous base material is positioned closer to the second surface than to the first surface.

[0008] A sealing device according to one aspect of the present disclosure is a sealing device for sealing a gap between a first member having an inner circumferential surface and a second member having an outer circumferential surface disposed inside the inner circumferential surface, comprising a sealing member fixed to one of the first member and the second member and sliding on the other member, wherein the sealing member comprises an elastic portion having a first surface and a second surface opposite to the first surface, the elastic portion is deformed by bending due to a compressive force between the first member and the second member such that compressive stress is generated on the first surface and tensile stress is generated on the second surface, the elastic portion comprises a rubber material and a sheet-like fibrous base material, the fibrous base material is positioned closer to the first surface than to the second surface. [Effects of the Invention]

[0009] This disclosure makes it possible to suitably reduce the bending deformation of the elastic part while taking advantage of the properties of the rubber material, such as its flexibility. [Brief explanation of the drawing]

[0010] [Figure 1] This is a cross-sectional view of a mechanism using a sealing device according to the first embodiment. [Figure 2]This is a diagram illustrating the test specimen used in bending tests. [Figure 3] This is a diagram to explain the bending test. [Figure 4] This figure shows the results of the bending test. [Figure 5] This is a cross-sectional view of a structure using a rubber molded product according to the second embodiment. [Figure 6] This is a cross-sectional view of a structure using a rubber molded product according to the third embodiment. [Modes for carrying out the invention]

[0011] Preferred embodiments of the present disclosure will be described below with reference to the attached drawings. Note that the dimensions and scale of parts in the drawings may differ from actual dimensions as appropriate, and some parts are shown schematically for ease of understanding. Furthermore, the scope of the present disclosure is not limited to these embodiments unless otherwise stated in the following description.

[0012] 1. First Embodiment 1-1. Overview of sealing devices Figure 1 is a cross-sectional view of mechanism 1 using a sealing device 10 according to the first embodiment. Mechanism 1 is a rotating mechanism such as a bearing mechanism found in various machines such as vehicles. As shown in Figure 1, mechanism 1 has a shaft 120, a housing 110, and a sealing device 10. The housing 110 is an example of a "first member". The shaft 120 is an example of a "second member". The sealing device 10 is an example of a "rubber molded product". For the sake of explanation, the outer shape of the shaft 120 is shown by a dashed line in Figure 1.

[0013] The housing 110 is a hollow structure having an inner circumferential surface 111. The inner circumferential surface 111 defines a hole H centered on axis AX. The hole H communicates with an internal space of the housing 110 (not shown). This internal space contains a fluid, such as oil or grease. Note that the shape of the housing 110 is not limited to the example shown in Figure 1.

[0014] The shaft 120 is a structure such as an axle having an outer circumferential surface 121, and is supported so as to be rotatable around the axis AX via a bearing (not shown). The shaft 120 is inserted into the hole H, and the outer circumferential surface 121 is positioned inside the inner circumferential surface 111. An annular space S is formed between the inner circumferential surface 111 and the outer circumferential surface 121. The sealing device 10 is positioned in space S. Note that the shaft 120 does not necessarily have to rotate around the axis AX. Also, the shape of the shaft 120 is not limited to the example shown in Figure 1.

[0015] The sealing device 10 is a structure that seals the aforementioned annular space S while allowing the shaft 120 to rotate relative to the housing 110. By positioning the sealing device 10 in space S, leakage of fluid from the internal space of the housing 110 and intrusion of foreign matter such as dust or water into the internal space of the housing 110 are prevented. The sealing device 10 includes a reinforcing ring 20, a sealing member 30, and a spring 40.

[0016] The parts of the sealing device 10 will be described in order below. In the following, one direction along the axis AX will be referred to as the "X1 direction," and the direction opposite to the X1 direction will be referred to as the "X2 direction." Here, the X1 direction is the direction from the outside to the inside of the housing 110 through the hole H along the axis AX. The X2 direction is the direction from the inside to the outside of the housing 110 through the hole H along the axis AX. In addition, in the following, the direction along the circumference of a circle centered on the axis AX may be referred to as the "circumferential direction," the direction perpendicular to the axis AX as the "radial direction," and the direction along the axis AX as the "axial direction."

[0017] The reinforcing ring 20 is an annular member that reinforces the sealing member 30 along the axis AX. The reinforcing ring 20 is positioned along the inner circumferential surface 111 of the hole H in the housing 110. The reinforcing ring 20 is made of a metallic material such as stainless steel or SPCC (cold-rolled steel), and is manufactured by pressing or forging. The material constituting the reinforcing ring 20 may be any material with a higher Young's modulus than the material constituting the sealing member 30, and is not limited to metallic materials; for example, it may be a ceramic material or a resin material.

[0018] When viewed in a cross-section cut by a plane including the axis AX, the reinforcing ring 20 has a substantially L-shaped cross-section. More specifically, the reinforcing ring 20 has a first portion 21 and a second portion 22. The first portion 21 is cylindrical along the inner peripheral surface 111 of the hole H of the housing 110. The second portion 22 is plate-shaped and projects radially inward from one end in the axial direction of the first portion 21 over the entire circumference. In the example shown in FIG. 1, the second portion 22 is connected to the end of the first portion 21 in the X2 direction and extends in a direction perpendicular to the axis AX.

[0019] Note that when viewed in a cross-section cut by a plane including the axis AX, the extending directions of the first portion 21 and the second portion 22 are not limited to the example shown in FIG. 1 and may intersect each other. However, from the viewpoint of suitably increasing the rigidity of the reinforcing ring 20, it is preferable that the extending directions of the first portion 21 and the second portion 22 are perpendicular to each other when viewed in a cross-section cut by a plane including the axis AX. Further, the cross-sectional shape of the reinforcing ring 20 is not limited to the example shown in FIG. 1, and for example, a shape in which one of the first portion 21 and the second portion 22 is omitted may be used.

[0020] The seal member 30 is an annular elastic body that is fixed to the reinforcing ring 20 and slides on the outer peripheral surface 121 of the shaft 120. The seal member 30 is fixed to the inner peripheral surface 111 together with the reinforcing ring 20 by press-fitting and is in close contact with the inner peripheral surface 111 over the entire circumference. Further, the shaft 120 is inserted inside the seal member 30, and the seal member 30 is in close contact with the outer peripheral surface 121 over the entire circumference.

[0021] The sealing member 30 includes a rubber material and sheet-like fiber base materials 34 and 35. The sealing member 30 is formed, for example, by insert molding using a reinforcing ring 20 and fiber base materials 34 and 35 as insert parts. Through this insert molding, the reinforcing ring 20 and fiber base materials 34 and 35 are joined to the sealing member 30 by vulcanization bonding. Here, the rubber material that constitutes a part of the sealing member 30 is embedded in the fiber base materials 34 and 35 when they are joined to the sealing member 30. In this way, when the fiber base materials 34 and 35 are integrally molded with the rubber material, the rubber material is embedded between the fibers of the fiber base materials 34 and 35, which has the advantage of making it easier to increase the durability of the sealing device 10 compared to the method in which the fiber base materials 34 and 35 are attached to the sealing member 30 with an adhesive. The fiber base materials 34 and 35 may also be joined to the sealing member 30 by chemical bonding or adhesive.

[0022] The rubber material is not particularly limited, but examples include synthetic rubbers such as nitrile rubber (NBR), hydrogenated nitrile rubber (H-NBR), acrylic rubber (ACM), or fluororubber (FKM), and silicone rubber. One of these may be used alone, or two or more may be used in combination in the form of a copolymer or blend.

[0023] The rubber material is not limited to synthetic rubber, but may also be a thermoplastic elastomer. Furthermore, crosslinking agents, crosslinking aids, or other additives may be added to the rubber material as needed. Examples of crosslinking agents include, but are not limited to, sulfur and peroxide vulcanizing agents. Examples of crosslinking aids include inorganic zinc oxide and magnesium oxide, and organic stearic acid and amines. In addition, inorganic fillers such as silica powder may be added to the rubber material, or conductive particles such as carbon black and metal powder may be added.

[0024] Each of the fiber base materials 34 and 35 is a sheet-like aggregate of fibers. Fiber base material 34 is provided on the lip 32, which is part of the sealing member 30 and will be described later, and reduces unintended deformation of the lip 32. Fiber base material 35 is provided on the lip 33, which is part of the sealing member 30 and will be described later, and reduces unintended deformation of the lip 33. By providing such fiber base materials 34 and 35 on the sealing member 30 or the lip 32 and 33, it is possible to realize a sealing member 30 or lip 32 and 33 with excellent sealing performance.

[0025] From the viewpoint of excellent shape stability, each of the fiber base materials 34 and 35 is preferably a woven or nonwoven fabric, and more preferably a woven fabric. When the fiber base materials 34 and 35 are nonwoven or woven fabrics, they are easy to handle during the manufacture of the rubber molded product. The fibers used in each of the fiber base materials 34 and 35 are synthetic fibers composed of resins such as polyester, nylon, aramid, vinylon, and urethane. However, the fibers used in each of the fiber base materials 34 and 35 are not limited to synthetic fibers, and may be natural fibers such as cotton, linen, silk, or animal hair.

[0026] Furthermore, if the fiber base material 34, 35 is a woven fabric, it is preferable that the warp or weft threads are arranged along the direction of the compressive or tensile stress described later. This allows for a more efficient increase in the bending rigidity of the lip 32, 33, described later, by the fiber base material 34, 35 compared to an arrangement where the warp or weft threads are arranged along a direction inclined towards the tensile or compressive stress.

[0027] As shown in Figure 1, the sealing member 30 has a fixing portion 31, a lip 32, and a lip 33. These are integrally constructed. Lips 32 and 33 are examples of "elastic portions".

[0028] The fixing portion 31 is part of the sealing member 30 and is an annular portion that is fixed around the entire circumference of the reinforcing ring 20. The fixing portion 31 is joined to the reinforcing ring 20 by vulcanization adhesive or the like.

[0029] In the example shown in Figure 1, the fixing portion 31 is provided along the reinforcing ring 20 and encloses the reinforcing ring 20. Thus, the reinforcing ring 20 is embedded in the fixing portion 31. Here, the fixing portion 31 has a portion that is positioned on the outer circumferential surface of the first portion 21 of the reinforcing ring 20. Therefore, this portion contacts the inner circumferential surface 111 of the housing 110. Such a fixing portion 31 is inserted into the hole H of the housing 110 with a predetermined overlap.

[0030] Lips 32 and 33 are each part of the sealing member 30, protruding from the fixing portion 31 toward the outer circumferential surface 121 of the shaft 120, and sliding against the outer circumferential surface 121.

[0031] In the example shown in Figure 1, the lip 32 is a sealing lip that prevents lubricant from leaking out of the housing 110. Specifically, the lip 32 extends in the X1 direction from the inner circumferential end of the fixing portion 31 over its entire circumferential range, and a projection 32a is provided on the inner circumferential surface of the lip 32. The projection 32a protrudes toward the outer circumferential surface 121 over its entire circumferential range and contacts the outer circumferential surface 121 in an elastically deformed state. In addition, a recess 32b is provided on the outer circumferential surface of the lip 32 in which the spring 40 is placed. The recess 32b is a groove that extends over its entire circumferential range and restricts the axial movement of the spring 40. Note that the shape of the lip 32 is not limited to the shape shown in Figure 1 and is arbitrary, as long as it can prevent lubricant from leaking out of the housing 110.

[0032] The spring 40 is an annular coil spring positioned in the recess 32b and pressing the lip 32 toward the outer surface 121; it is also called a garter spring. The spring 40 is positioned in the recess 32b in a state of elastic deformation, expanding away from the axis AX. The restoring force resulting from this elastic deformation causes the spring 40 to press the lip 32 toward the outer surface 121 of the shaft 120. The spring 40 is made of spring steel, such as stainless steel.

[0033] The lip 32 has a first surface F1a and a second surface F2a opposite to the first surface F1a. The first surface F1a is part of the outer circumferential surface of the lip 32. The second surface F2a is part of the inner circumferential surface of the lip 32. The lip 32 is bent and deformed by the compressive force between the housing 110 and the shaft 120, causing compressive stress on the first surface F1a and tensile stress on the second surface F2a. That is, in the normal operating state when incorporated into the mechanism 1, the lip 32 is bent and deformed so that the first surface F1a becomes concave and the second surface F2a becomes convex. This, combined with the pressing force of the spring 40, provides the desired contact pressure of the lip 32 against the shaft 120.

[0034] A fibrous base material 34 is provided on the first surface F1a. Therefore, the fibrous base material 34 is positioned closer to the first surface F1a than to the second surface F2a. In other words, the fibrous base material 34 is positioned on the first surface F1a side with respect to the center ANa in the thickness direction of the lip 32.

[0035] Because the fibrous base material 34 is positioned offset from the central ANa in this way, the first surface F1a is less prone to stretching than the second surface F2a due to the fibrous base material 34. This increases the bending rigidity of the lip 32 in bending deformation that generates tensile stress on the first surface F1a and compressive stress on the second surface F2a. Furthermore, since the elongation of the second surface F2a is hardly restricted by the fibrous base material 34, the properties of the rubber material, such as flexibility, can be utilized in bending deformation of the lip 32 that generates compressive stress on the first surface F1a and tensile stress on the second surface F2a.

[0036] In this way, the flexibility and other properties of the rubber material can be utilized on the second surface F2a while the first surface F1a can be made less prone to stretching by the fiber base material 34. Therefore, the bending rigidity of the lip 32 can be increased in bending deformation that generates compressive stress on the second surface F2a and tensile stress on the first surface F1a, while utilizing the flexibility and other properties of the rubber material. As a result, unintended deformation of the sealing member 30 can be reduced when assembling the sealing device 10, etc.

[0037] Here, the bending rigidity of the lip 32 in the direction of bending deformation that should occur under the normal operating conditions of the sealing device 10 can be reduced, while the bending rigidity of the lip 32 in the opposite direction can be increased. As a result, the contact pressure of the lip 32 with respect to the shaft 120 can be optimized, while unintended deformation of the lip 32 can be reduced. Therefore, for example, when inserting the shaft 120 into the inside of the sealing member 30, deformation such that the first surface F1a gets caught between the second surface F2a and the shaft 120 can be prevented.

[0038] In this embodiment, the fiber base material 34 is exposed to the first surface F1a. This increases the bending rigidity of the lip 32 during bending deformation, generating tensile stress on the first surface F1a and compressive stress on the second surface F2a, compared to the embodiment in which the fiber base material is located near the center ANa. At least a portion of the fiber base material 34 may be positioned between the first surface F1a and the center ANa. However, the closer the fiber base material 34 is to the first surface F1a, the higher the bending rigidity of the lip 32 during bending deformation can be.

[0039] Furthermore, since the fibrous base material 34 is provided on the first surface F1a, it does not obstruct contact between the lip 32 and the shaft 120. In this way, the fibrous base material 34 is positioned to avoid the contact area between the lip 32 and the shaft 120. This prevents the adhesion between the lip 32 and the shaft 120 from being impaired by irregularities caused by the fibrous base material 34.

[0040] On the other hand, the lip 33 is a dust lip that prevents foreign matter such as dust or water from entering the housing 110. Specifically, the lip 33 is blade-shaped and extends from the inner circumferential end of the fixing portion 31 towards the outer circumferential surface 121, inclined in the X2 direction over its entire circumference, and contacts the outer circumferential surface 121. The shape of the lip 33 is not limited to the shape shown in Figure 1, but is arbitrary and only needs to be able to prevent foreign matter such as dust or water from entering the housing 110.

[0041] The lip 33 has a first surface F1b and a second surface F2b opposite to the first surface F1b. The first surface F1b is part of the outer circumferential surface of the lip 33. The second surface F2b is part of the inner circumferential surface of the lip 33. The lip 33 is bent and deformed by the compressive force between the housing 110 and the shaft 120, causing compressive stress on the first surface F1b and tensile stress on the second surface F2b. That is, in the normal operating state when incorporated into the mechanism 1, the lip 33 is bent and deformed so that the first surface F1b becomes concave and the second surface F2b becomes convex. This provides the desired contact pressure of the lip 33 against the shaft 120.

[0042] A fibrous base material 35 is provided on the first surface F1b. Therefore, the fibrous base material 35 is positioned closer to the first surface F1b than to the second surface F2b. In other words, the fibrous base material 35 is positioned on the first surface F1b side with respect to the center ANb in the thickness direction of the lip 33.

[0043] Because the fibrous base material 35 is positioned offset from the central ANb in this way, the first surface F1b is less likely to stretch than the second surface F2b due to the fibrous base material 35. This increases the bending rigidity of the lip 33 in bending deformation that generates tensile stress on the first surface F1b and compressive stress on the second surface F2b. Furthermore, since the elongation of the second surface F2b is hardly restricted by the fibrous base material 35, the flexibility and other properties of the rubber material can be utilized in bending deformation of the lip 33 that generates compressive stress on the first surface F1b and tensile stress on the second surface F2b.

[0044] In this way, the flexibility and other properties of the rubber material can be utilized on the second surface F2b while the first surface F1b can be made less prone to stretching by the fiber base material 35. Therefore, the bending rigidity of the lip 33 can be increased during bending deformation that generates compressive stress on the second surface F2b and tensile stress on the first surface F1b, while utilizing the flexibility and other properties of the rubber material. As a result, unintended deformation of the sealing member 30 can be reduced when assembling the sealing device 10, etc.

[0045] Here, the bending rigidity of the lip 33 in the direction of bending deformation that should occur under the normal operating conditions of the sealing device 10 can be reduced, while the bending rigidity of the lip 33 in the opposite direction can be increased. As a result, the contact pressure of the lip 33 with respect to the shaft 120 can be optimized, while unintended deformation of the lip 33 can be reduced. For example, when inserting the shaft 120 into the inside of the sealing member 30, deformation such that the first surface F1b is caught between the second surface F2b and the shaft 120 can be prevented.

[0046] In this embodiment, the fibrous base material 35 is exposed to the first surface F1b. This increases the bending rigidity of the lip 33 during bending deformation, generating tensile stress on the first surface F1b and compressive stress on the second surface F2b, compared to the embodiment in which the fibrous base material is located near the central ANb. At least a portion of the fibrous base material 35 may be positioned between the first surface F1b and the central ANb. However, the closer the fibrous base material 35 is to the first surface F1b, the higher the bending rigidity of the lip 33 during bending deformation can be.

[0047] Furthermore, since the fibrous base material 35 is provided on the first surface F1b, it does not obstruct contact between the lip 33 and the shaft 120. In this way, the fibrous base material 35 is positioned to avoid the contact area between the lip 33 and the shaft 120. This prevents the adhesion between the lip 33 and the shaft 120 from being impaired by irregularities caused by the fibrous base material 35.

[0048] 1-2. Bending rigidity of the elastic part The bending stiffness of the elastic part will be explained below. Figure 2 is a diagram illustrating the test specimen 200 used in the bending test. Figure 2 schematically shows the manufacturing process of the test specimen 200.

[0049] In manufacturing the test piece 200, first, an unvulcanized rubber test piece 201 and a fiber substrate 202 are prepared, as shown on the left side of Figure 2. Next, as shown in the center of Figure 2, the test piece 201 and the fiber substrate 202 are pressed and heated between the upper mold 301 and the lower mold 302 while stacked on top of each other, so that the fiber substrate 202 is attached to one side of the test piece 201 by vulcanization adhesion. This results in the test piece 200, as shown on the right side of Figure 2. Although not shown, a test piece with the fiber substrate 202 attached to both sides of the test piece 201 can be similarly obtained by using an unvulcanized rubber test piece 201 and two fiber substrates 202.

[0050] Here, the thickness of the fiber base material 202 is 0.3 mm. The thickness of the test specimen 200 is 2 mm. The plan view shape of the test specimen 200 is a rectangle.

[0051] The test specimen 200 described above has a first surface F1c and a second surface F2c opposite to the first surface F1c. The first surface F1c is one of the board surfaces of the test specimen 200. A fiber base material 202 is provided on the first surface F1c. The second surface F2c is the other board surface of the test specimen 200. Thus, in the test specimen 200, the fiber base material 202 is positioned closer to the first surface F1c than to the second surface F2c. That is, in the test specimen 200, the fiber base material 202 is positioned on the side of the first surface F1c than the center ANc in the thickness direction of the test specimen 200.

[0052] Figure 3 is a diagram illustrating the bending test. In the bending test, as shown in Figure 3, a load is applied between the upper die 301 and the lower die 302 such that a pair of opposing sides of the test specimen 200 move closer together while the test specimen 200 is bent. At this time, the load at each curvature of the test specimen 200 is measured as the bending stiffness. This curvature is the reciprocal of the radius of curvature of the test specimen 200. The radius of curvature of the test specimen 200 is measured as half the distance between the pair of sides.

[0053] In the example shown in Figure 3, the bending stiffness of test piece 200 is measured when it is bent so that the first surface F1c is on the inside, i.e., the compression side. Although not shown, the bending stiffness of test piece 200 is similarly measured when it is bent so that the first surface F1c is on the outside, i.e., the tension side. The bending stiffness is also similarly measured for test pieces 201 with fiber substrates 202 attached to both sides, and for test pieces without fiber substrates 202.

[0054] Figure 4 shows the results of a bending test. In Figure 4, the results of a bending test of test piece 200 are shown when EPDM rubber with a hardness of 70 is used as test piece 201 and polyester satin weave is used as the fiber base material 202. In Figure 4, the horizontal axis represents curvature and the vertical axis represents bending stiffness. In Figure 4, the results when test piece 200 is bent so that the first surface F1c is on the compression side are shown by a dashed line, the results when test piece 200 is bent so that the first surface F1c is on the tension side are shown by a dashed line, the results when test piece 200 is bent so that the first surface F1c is on the tension side are shown by a dashed line, the results when test piece 201 has fiber base material 202 attached to both sides are shown by a dashed line, and the results when test piece 201 does not have fiber base material 202 attached are shown by a solid line.

[0055] As shown in Figure 4, when test piece 200 is bent and deformed so that the first surface F1c is on the compression side, the bending stiffness is almost the same as that of a test piece without the fiber substrate 202 attached. In contrast, when test piece 200 is bent and deformed so that the first surface F1c is on the tension side, the bending stiffness is approximately four times that of a test piece without the fiber substrate 202 attached, when the curvature is 0.5. Furthermore, when test piece 201 has the fiber substrate 202 attached to both sides, the bending stiffness is approximately 5.7 times that of a test piece without the fiber substrate 202 attached, when the curvature is 0.5.

[0056] As is clear from the above, in the lip 32 of the sealing device 10, by positioning the fibrous base material 34 closer to the first surface F1a than to the second surface F2a, it is possible to reduce the bending stiffness in the direction of bending deformation that should occur under the normal use of the sealing device 10, while increasing the bending stiffness in the opposite direction. Therefore, the bending stiffness of the lip 32 in the direction of bending deformation that should occur under the normal use of the sealing device 10 is different from the bending stiffness of the lip 32 in the opposite direction. This makes it possible to suitably increase the bending stiffness of the lip 32 while making use of the properties of the rubber material, such as flexibility.

[0057] Similarly, in the lip 33, by positioning the fibrous base material 35 closer to the first surface F1b than to the second surface F2b, it is possible to reduce the bending stiffness in the direction of the bending deformation that should occur under the normal operating conditions of the sealing device 10, while increasing the bending stiffness in the opposite direction. Therefore, the bending stiffness of the lip 33 in the direction of the bending deformation that should occur under the normal operating conditions of the sealing device 10 is different from the bending stiffness of the lip 33 in the opposite direction. This makes it possible to suitably increase the bending stiffness of the lip 33 while taking advantage of the properties of the rubber material, such as flexibility.

[0058] 2. Second Embodiment The second embodiment of this disclosure will be described below. In the following description, matters similar to those described in the first embodiment will be omitted as appropriate.

[0059] Figure 5 is a cross-sectional view of a structure 2 using a rubber molded product 50 according to the second embodiment. The structure 2 is a toy wheel used in toys such as radio-controlled cars, and comprises a rubber molded product 50 and a wheel 60.

[0060] The wheel 60 is a wheel used for toys and is a structure having an outer circumferential surface 61 centered on the axis AX1. A rubber molded product 50 is fitted onto the outer circumferential surface 61. The rubber molded product 50 is the tire body used for toys and is composed of a cylindrical elastic part 51.

[0061] The molded rubber product 50 comprises a rubber material and a sheet-like fibrous base material 52. The molded rubber product 50 is formed, for example, by insert molding in which the fibrous base material 52 is used as an insert. Through this insert molding, the fibrous base material 52 is bonded to the molded rubber product 50 by vulcanization adhesion. The fibrous base material 52 may also be bonded to the molded rubber product 50 by chemical adhesion or an adhesive.

[0062] The elastic portion 51 has a first surface F1d and a second surface F2d opposite to the first surface F1d. The first surface F1d is the outer circumferential surface of the rubber molded product 50. The second surface F2d is the inner circumferential surface of the rubber molded product 50.

[0063] The elastic portion 51, when fitted onto the wheel 60, is subjected to an external force or load such that a greater tensile stress is generated in the circumferential direction on the second surface F2d than on the first surface F1d. At this time, the rubber molded product 50 is elastically deformed and is fixed to the wheel 60 by the restoring force of this elastic deformation.

[0064] On the other hand, as the structure 2 rotates around the axis AX2, centrifugal force acts on the rubber molded product 50 in such a way that it weakens the restoring force. As the rotational speed increases, the rubber molded product 50 becomes more likely to detach from the wheel 60.

[0065] Therefore, a fibrous base material 52 is provided on the second surface F2d. Consequently, the fibrous base material 52 is positioned closer to the second surface F2d than to the first surface F1d. As a result, the second surface F2a is less stretchable than the first surface F1d due to the fibrous base material 52, thereby reducing deformation of the elastic portion 51 that causes the second surface F2d to stretch in the circumferential direction. This prevents the rubber molded product 50 from coming off the wheel 60. Furthermore, since the elongation of the first surface F1a is hardly restricted by the fibrous base material 52, the flexibility and other properties of the rubber material can be utilized on the first surface F1d. This allows the rubber molded product 50 to function optimally as the tire body.

[0066] In this embodiment, the fibrous base material 52 is exposed to the second surface F2d. This allows for a favorable reduction in deformation of the elastic portion 51 such that the second surface F2d stretches in the circumferential direction, compared to an embodiment in which the fibrous base material 52 is positioned between the second surface F2d and the center ANd in the thickness direction of the elastic portion 51. In other words, the deformation of the elastic portion 51 is reduced compared to an embodiment in which the fibrous base material 52 is positioned between the second surface F2d and the center ANd in the thickness direction of the elastic portion 51.

[0067] The second embodiment described above also makes it possible to suitably reduce the deformation of the elastic portion 51 while making use of the properties of the rubber material, such as its flexibility.

[0068] 3. Third Embodiment The third embodiment of this disclosure will be described below. In the following description, matters similar to those described in the first embodiment will be omitted as appropriate.

[0069] Figure 6 is a cross-sectional view of a structure 3 using a rubber molded product 80 according to the third embodiment. The structure 3 is a pressure regulating valve that adjusts the pressure in the internal space S1 of the casing 70, and is used, for example, as an explosion-proof valve for the cells of a battery module such as a lithium-ion battery. The casing 70 is provided with a plurality of holes 71 for connecting the internal space S1 and the external space S2. The plurality of holes 71 are arranged along the circumferential direction centered on the axis AX2. The structure 3 closes each hole 71 when the pressure in the internal space S1 is below a predetermined level, and opens each hole 71 when the pressure in the internal space S1 is above a predetermined level. This adjusts the pressure in the internal space S1 of the casing 70 to be below a predetermined level.

[0070] Structure 3 comprises a rubber molded product 80 and a fixing member 90.

[0071] The rubber molded product 80 is an umbrella-shaped elastic body having a base portion 81 and a membrane portion 82. The membrane portion 82 is an example of an "elastic portion".

[0072] The base portion 81 is part of the rubber molded product 80 and is fixed to the casing 70. The base portion 81 is positioned on the axis AX2 and has a hole 81a along the axis AX2. A fixing member 90 is inserted into the hole 81a.

[0073] The membrane portion 82 is a part of the rubber molded product 80 and is a membrane-like portion positioned in the external space S2 so as to cover the aforementioned plurality of holes 71 collectively. The membrane portion 82 extends away from the base portion 81 in a direction away from the axis AX2 and has a circular outer shape centered on the axis AX2 when viewed in the direction along the axis AX2. Furthermore, when viewed in a direction perpendicular to the axis AX2, the membrane portion 82 has a curved shape that is convex in the direction from the internal space S1 toward the external space S2. The peripheral end face of the membrane portion 82 functions as a sealing surface 82a that contacts the casing 70.

[0074] The fixing member 90 is a rod-shaped member for fixing the rubber molded product 80 to the casing 70. The fixing member 90 is inserted into the hole 81a of the base portion 81 and then fitted into the hole 72 of the casing 70, thereby fixing the rubber molded product 80 to the casing 70. At this time, the shape of the fixing member 90 is not limited to the example shown in Figure 6, but is arbitrary.

[0075] In the structure 3 outlined above, when the pressure in the internal space S1 is below a predetermined level, the restoring force due to the elastic deformation of the membrane portion 82 causes the sealing surface 82a to adhere tightly to the casing 70 around its entire circumference, thus closing the hole 71 with the rubber molded product 80. On the other hand, when the pressure in the internal space S1 is above a predetermined level, the pressure in the internal space S1 deforms the membrane portion 82 toward the external space S2 against the restoring force, creating a gap between the sealing surface 82a and the casing 70, thus releasing the closure of the hole 71 by the rubber molded product 80.

[0076] The molded rubber product 80 comprises a rubber material and a sheet-like fibrous base material 83. The molded rubber product 80 is formed, for example, by insert molding using the fibrous base material 83 as an insert. Through this insert molding, the fibrous base material 83 is bonded to the molded rubber product 80 by vulcanization adhesion. The fibrous base material 83 may also be bonded to the molded rubber product 80 by chemical adhesion or an adhesive.

[0077] The membrane portion 82 has a first surface F1e and a second surface F2e opposite to the first surface F1e. The first surface F1e is the surface of the membrane portion 82 facing the external space S2. The second surface F2e is the surface of the membrane portion 82 facing the internal space S1. The membrane portion 82 is subjected to an external force or load such that compressive stress is generated on the first surface F1e and tensile stress is generated on the second surface F2e in order to obtain a restoring force by elastic deformation as described above. Therefore, the rigidity of the membrane portion 82 is set so that the hole 71 opens and closes at a desired pressure.

[0078] On the other hand, the first surface F1e is exposed to the external space S2 and may be subjected to external forces, such as high-pressure water ejected from a high-pressure washer. In this case, it is conceivable that the unintended deformation of the membrane portion 82 may cause the blockage of the hole 71 by the rubber molded product 80 to be released.

[0079] Therefore, a fibrous base material 83 is provided on the first surface F1e. Consequently, the fibrous base material 83 is positioned closer to the first surface F1e than to the second surface F2e. In other words, the fibrous base material 83 is positioned on the first surface F1e side with respect to the center ANe in the thickness direction of the film portion 82.

[0080] Because the fibrous base material 83 is positioned offset from the central ANe in this way, the first surface F1e is less likely to stretch due to the fibrous base material 34 compared to the second surface F2e. This increases the bending rigidity of the membrane portion 82 in bending deformation that generates tensile stress on the first surface F1e and compressive stress on the second surface F2e. Furthermore, since the elongation of the second surface F2e is hardly restricted by the fibrous base material 83, the flexibility and other properties of the rubber material can be utilized in bending deformation of the membrane portion 82 that generates compressive stress on the first surface F1e and tensile stress on the second surface F2e. This reduces the likelihood of the closure of the holes 71 by the rubber molded product 80 being released due to unintended deformation of the membrane portion 82.

[0081] The third embodiment described above also makes it possible to suitably reduce the deformation of the membrane portion 82 while making use of the properties of the rubber material, such as its flexibility.

[0082] 4. Variations Each of the forms exemplified above can be modified in various ways. Specific examples of modifications that can be applied to each of the aforementioned forms are given below. Two or more forms arbitrarily selected from the following examples can be combined as appropriate, provided they do not contradict each other.

[0083] 4-1. Variation 1 In the first embodiment described above, an example is shown in which the sealing device 10 has fiber base materials 34 and 35, but the device is not limited to this embodiment, and for example, one of the fiber base materials 34 and 35 may be omitted. Also, the sealing member 30 may have fiber base materials other than the fiber base materials 34 and 35.

[0084] 4-2. Variation 2 In the first embodiment described above, an example is shown in which the sealing device 10 has lips 32 and 33, but the invention is not limited to this embodiment, and for example, one of the lips 32 and 33 may be omitted.

[0085] 4-3. Variation 3 In the aforementioned first embodiment, an example is provided in which a sealing member 30 that slides on the shaft 120 is used. However, the present disclosure is not limited to this embodiment, and can also be applied to an embodiment in which a sealing member that slides on the housing 110 is used. In this case, the sealing member is fixed to the shaft 120, and for example, a fibrous material is provided on the lip of the sealing member.

[0086] 4-4. Variation 4 This disclosure is not limited to the rubber molded articles exemplified in the embodiments described above, but is applicable to various rubber molded articles having elastic parts that are subjected to bending loads or external forces.

[0087] 5. Addendum From the above embodiments or modifications, for example, the following embodiments can be understood.

[0088] (Note 1) A first embodiment of a preferred example of a rubber molded article of the present disclosure is a rubber molded article that is subjected to a load or external force such that, under normal use conditions, compressive stress is generated on the first surface and tensile stress is generated on the second surface, wherein the elastic part comprises a rubber material and a sheet-like fibrous base material, and the fibrous base material is positioned closer to the first surface than to the second surface.

[0089] In the above embodiment, since the first surface is less stretchable than the second surface due to the fibrous base material, deformation of the elastic part that would generate tensile stress on the first surface and compressive stress on the second surface can be reduced. Furthermore, since the elongation of the second surface is hardly restricted by the fibrous base material, the properties of the rubber material, such as flexibility, can be utilized on the second surface.

[0090] (Note 2) In the second embodiment, which is a preferred example of the first embodiment, the fibrous substrate is exposed on the first surface. In the above embodiment, deformation of the elastic portion that generates tensile stress on the first surface and compressive stress on the second surface can be suitably reduced.

[0091] (Note 3) A third embodiment, which is a preferred example of a rubber molded article of the present disclosure, is a rubber molded article that includes an elastic portion having a first surface which is an outer circumferential surface and a second surface which is an inner circumferential surface, and is subjected to a load or external force such that a greater tensile stress is generated in the circumferential direction on the second surface than on the first surface, wherein the elastic portion includes a rubber material and a sheet-like fibrous base material, and the fibrous base material is positioned closer to the second surface than to the first surface. In this embodiment, since the second surface is less stretchable than the first surface due to the fibrous base material, deformation of the elastic portion such that the second surface stretches in the circumferential direction can be reduced. Furthermore, since the elongation of the first surface is hardly restricted by the fibrous base material, the properties of the rubber material, such as flexibility, can be utilized on the first surface.

[0092] (Note 4) In the fourth embodiment, which is a preferred example of the third embodiment, the fibrous substrate is exposed on the second surface. In the above embodiments, deformation of the elastic portion such that the second surface stretches in the circumferential direction can be suitably reduced.

[0093] (Note 5) In the fifth embodiment, which is a preferred example of any of the first to fourth embodiments, the fiber base material is a nonwoven fabric or a woven fabric. In the above embodiments, the handling of the fiber base material is easy during the manufacture of the rubber molded product.

[0094] (Note 6) In the sixth embodiment, which is a preferred example of the fifth embodiment, the fibrous base material is a woven fabric, and the warp or weft threads are arranged along the direction of the compressive stress or the tensile stress. In the above embodiments, the effect of increasing the rigidity of the elastic part by the fibrous base material can be obtained more efficiently than in embodiments in which the warp or weft threads are arranged along a direction inclined in the direction of the tensile stress or the compressive stress.

[0095] (Note 7) In the seventh embodiment, which is a preferred example of the fifth or sixth embodiment, the fiber base material is integrally molded with the rubber material. In the above embodiments, since the rubber material is embedded between the fibers of the fiber base material, there is an advantage in that the durability of the rubber molded product is easier to improve compared to the embodiment in which the fiber base material is attached to the elastic part with an adhesive.

[0096] (Note 8) In the eighth embodiment, which is a preferred example of any of the first to seventh embodiments, the elastic portion is part of a sealing member that seals the gap between a first member having an inner circumferential surface and a second member having an outer circumferential surface arranged inside the inner circumferential surface. In the above embodiments, a sealing member with excellent sealing performance can be realized.

[0097] (Note 9) In the ninth embodiment, which is a preferred example of any of the first to eighth embodiments, the bending stiffness of the elastic part in the direction of bending deformation is different from the bending stiffness of the elastic part in the direction opposite to the direction of bending deformation. In the above embodiments, the bending stiffness of the elastic part can be suitably increased while making use of the properties of the rubber material, such as flexibility.

[0098] (Note 10) A tenth preferred embodiment of the sealing device of the present disclosure is a sealing device for sealing a gap between a first member having an inner circumferential surface and a second member having an outer circumferential surface disposed inside the inner circumferential surface, comprising a sealing member fixed to one of the first member and the second member and sliding on the other member, wherein the sealing member comprises an elastic portion having a first surface and a second surface opposite to the first surface, the elastic portion is deformed by bending due to a compressive force between the first member and the second member such that compressive stress is generated on the first surface and tensile stress is generated on the second surface, the elastic portion comprises a rubber material and a sheet-like fibrous base material, the fibrous base material is positioned closer to the first surface than to the second surface.

[0099] In the above embodiment, since the fibrous base material is positioned closer to the first surface than to the second surface, the flexibility and other properties of the rubber material can be utilized on the second surface while making the first surface less prone to stretching by the fibrous base material. Therefore, the bending rigidity of the elastic part in bending deformation that generates compressive stress on the second surface and tensile stress on the first surface, while utilizing the flexibility and other properties of the rubber material, can be increased. As a result, unintended deformation of the sealing member can be reduced when assembling the sealing device, etc.

[0100] (Note 11) In the 11th embodiment, which is a preferred example of the 10th embodiment, the elastic portion is a lip that slides against the inner or outer circumferential surface. In the above embodiment, unintended deformation of the lip can be reduced, and a lip with excellent sealing properties can be realized.

[0101] (Note 12) In the twelfth embodiment, which is a preferred example of the eleventh embodiment, the fibrous substrate is arranged to avoid the contact area between the lip and the other member. This prevents the adhesion between the lip and the other member from being impaired by irregularities caused by the fibrous substrate. [Explanation of Symbols]

[0102] 1... Mechanism, 2... Structure, 3... Structure, 10... Sealing device (rubber molded product), 20... Reinforcing ring, 21... First part, 22... Second part, 30... Seal member, 31... Fixing part, 32... Lip (elastic part), 32a... Projection, 32b... Recess, 34... Fiber base material, 33... Lip (elastic part), 35... Fiber base material, 40... Spring, 50... Rubber molded product, 51... Elastic part, 52... Fiber base material, 60... Wheel, 61... Outer surface, 70... Casing, 71... Hole, 72... Hole, 80... Rubber molded product, 81... Base, 81a... Hole, 82... Membrane part (elastic part), 82a... Seal surface, 83... Fiber base material, 90 …fixing member, 110…housing, 111…inner surface, 120…shaft, 121…outer surface, 200…test piece, 201…test piece, 202…fiber base material, 301…upper mold, 302…lower mold, ANa…center, ANb…center, ANC…center, ANd…center, ANe…center, AX…axis, AX1…axis, AX2…axis, F1a…first surface, F1b…first surface, F1c…first surface, F1d…first surface, F1e…first surface, F2a…second surface, F2b…second surface, F2c…second surface, F2d…second surface, F2e…second surface, H…hole, S…space, S1…internal space, S2…external space.

Claims

1. A rubber molded product having an elastic portion having a first surface and a second surface opposite to the first surface, wherein under normal use conditions, a load or external force is applied such that compressive stress is generated on the first surface and tensile stress is generated on the second surface, The elastic portion comprises a rubber material and a sheet-like fibrous base material. The fibrous substrate is positioned closer to the first surface than to the second surface. Rubber molded product.

2. The fibrous substrate is exposed on the first surface, The rubber molded article according to claim 1.

3. A rubber molded product having an elastic portion having a first surface which is an outer circumferential surface and a second surface which is an inner circumferential surface, wherein the second surface is subjected to a load or external force such that a greater tensile stress is generated in the circumferential direction on the second surface than on the first surface, The elastic portion comprises a rubber material and a sheet-like fibrous base material. The fibrous substrate is positioned closer to the second surface than to the first surface. Rubber molded product.

4. The fibrous substrate is exposed on the second surface, The rubber molded article according to claim 3.

5. The aforementioned fibrous base material is a nonwoven fabric or a woven fabric. The rubber molded article according to claim 1.

6. The fibrous base material is a woven fabric, and the warp or weft threads are arranged along the direction of the compressive stress or the tensile stress. The rubber molded article according to claim 5.

7. The fibrous substrate is integrally molded with the rubber material. The rubber molded article according to claim 5 or 6.

8. The elastic portion is part of a sealing member that seals the gap between a first member having an inner circumferential surface and a second member having an outer circumferential surface positioned inside the inner circumferential surface. The rubber molded article according to claim 1.

9. The bending stiffness of the elastic portion in the direction of the bending deformation is different from the bending stiffness of the elastic portion in the direction opposite to the direction of the bending deformation. The rubber molded article according to claim 1.

10. A sealing device for sealing the gap between a first member having an inner circumferential surface and a second member having an outer circumferential surface disposed inside the inner circumferential surface, The first member and the second member are provided with a sealing member that is fixed to one of the members and slides on the other member. The sealing member is The elastic portion comprises a first surface and a second surface opposite to the first surface, The elastic portion is bent and deformed by the compressive force between the first member and the second member such that compressive stress is generated on the first surface and tensile stress is generated on the second surface. The elastic portion comprises a rubber material and a sheet-like fibrous base material. The fibrous substrate is positioned closer to the first surface than to the second surface. Sealing device.

11. The elastic portion is a lip that slides against the inner or outer circumferential surface. The sealing device according to claim 10.

12. The fibrous substrate is arranged so as to avoid contact areas between the lip and the other member. The sealing device according to claim 11.

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