Liquid-sealed bushing and method for manufacturing liquid-sealed bushing

Abstract

To provide a liquid seal bush or the like reduced in cost and excellent in manufacturability.SOLUTION: A plurality of liquid chambers 5 which are spaced apart from each other in a circumferential direction between the outer cylinder member 2 and the rubber elastic body 4 and in which a hydraulic fluid L is accommodated, and an orifice flow path 6 which allows the plurality of liquid chambers 5 to communicate with each other, the rubber elastic body 4 and the outer cylinder member 2 are sealed by directly joining both end sides of the plurality of liquid chambers 5 and the orifice flow path 6 in the axial direction of the outer cylinder member 2.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a liquid-sealed bushing and a method for manufacturing the liquid-sealed bushing. [Background technology]

[0002] As an example of a liquid-sealed bushing, Patent Document 1 discloses a liquid-filled vibration-damping device used for automobile suspension bushings, etc. This liquid-filled vibration-damping device has a rubber elastic body interposed between an inner cylinder and an outer cylinder, and a pair of recesses formed on either side of the inner cylinder at the axial center of the rubber elastic body are filled with liquid to form liquid chambers, with the pair of liquid chambers communicating with each other via a restricting passage.

[0003] The manufacturing method for this liquid-filled vibration-damping device involves first placing the inner cylinder and a ring, which is placed between the rubber elastic body and the outer cylinder, in a rubber vulcanization mold, and then injecting rubber material between them and vulcanizing to form a rubber molded member in which the inner cylinder and the ring are vulcanized and bonded together. At this time, a rubber film is formed on the outer periphery of the ring.

[0004] Next, the restricting passage component is fitted onto the formed rubber molded member and inserted into the outer cylinder, and the outer cylinder is fixed by drawing in the radial direction and compressing the rubber elastic body. After that, the upper and lower axial ends of the outer cylinder are crimped to seal the rubber membrane on the outer periphery of the ring and the outer cylinder. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 10-231884 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in order to form a pair of liquid chambers and a restrictive passageway connecting them between the rubber elastic body and the outer cylinder, the above-mentioned liquid-filled vibration-damping device (liquid-sealed bushing) requires the formation of recesses for the liquid chambers in a pre-formed rubber molded member, as well as the provision of a ring for joining to the outer cylinder. Furthermore, restrictive passage-forming members are also required to form the restrictive passageway connecting the liquid chambers, and there are problems with the high cost due to the need for many parts, and the complicated manufacturing process due to the large number of manufacturing steps.

[0007] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a liquid-sealed bushing that is cost-effective and easy to manufacture, and a method for manufacturing the liquid-sealed bushing. [Means for solving the problem]

[0008] In order to achieve the above-mentioned object, the present invention provides a liquid-sealed bushing comprising an outer tube member, an inner tube member disposed within the hollow portion of the outer tube member, and a rubber elastic body interposed between the outer tube member and the inner tube member, wherein a plurality of liquid chambers spaced apart in the circumferential direction and containing hydraulic fluid are provided between the outer tube member and the rubber elastic body, and an orifice flow path connecting the plurality of liquid chambers, and wherein the rubber elastic body and the outer tube member are directly joined and sealed at both ends of the plurality of liquid chambers and the orifice flow path in the axial direction of the outer tube member. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a liquid-sealed bushing that is cost-effective and easy to manufacture, and a method for manufacturing the liquid-sealed bushing. Problems, configurations, and effects other than those described above will become clear from the description of the following embodiments. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view of a liquid-sealed bushing according to an embodiment, taken along an axial direction. [Figure 2] 2 is a cross-sectional view taken along the line AA in FIG. 1. [Figure 3]3 is a cross-sectional view of FIG. 2 taken along line B-B. [Figure 4] FIG. 4 is a flow chart showing a method for manufacturing a liquid-sealed bushing. [Figure 5] FIG. 10 is a cross-sectional view showing a state in which a core forming die is disposed inside an outer cylindrical member. [Figure 6] FIG. 10 is a view showing an outer cylindrical member provided with a core. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In this embodiment, a liquid-sealed bushing used in a connecting portion between a vehicle body and a suspension arm will be described as an example.

[0012] 1 to 3, the liquid-sealed bushing 1 according to this embodiment is configured to include an outer cylindrical member 2, an inner cylindrical member 3 arranged coaxially within the hollow portion of the outer cylindrical member 2, and a rubber elastic body 4 that is interposed between the outer cylindrical member 2 and the inner cylindrical member 3 to connect them. Between the outer cylindrical member 2 and the rubber elastic body 4 of the liquid-sealed bushing 1, there are provided a plurality of liquid chambers 5 that contain a working fluid L, and orifice flow paths 6 that connect the liquid chambers 5 together.

[0013] In this embodiment, two liquid chambers 5 are provided at two locations circumferentially spaced apart from each other on either side of the inner cylindrical member 3, at 180 degrees opposite each other. An orifice flow path 6 is provided along the inner peripheral surface 2A of the outer cylindrical member 2, and connects the two liquid chambers 5 on both sides of each liquid chamber 5.

[0014] The inner cylindrical member 3 is a cylindrical member made of metal and is disposed at the center of the liquid-sealed bushing 1. The inner cylindrical member 3 has a hollow hole 3A that passes through along the axial direction, and is fixed to a suspension arm or the like via a bolt that is inserted into the hollow hole 3A. Both axial ends of the inner cylindrical member 3 protrude beyond both axial ends of the outer cylindrical member 2.

[0015] The outer cylindrical member 2 is a cylindrical member made of metal, and is disposed radially outward of and spaced from the inner cylindrical member 3. An outer peripheral surface 2B of the outer cylindrical member 2 is a portion that is held by a bracket or the like on the vehicle body side.

[0016] Two communication holes 2C that communicate between the inside and outside of the outer cylindrical member 2 are provided in the outer cylindrical member 2, spaced apart in the circumferential direction of the outer cylindrical member 2. The communication holes 2C are provided at two locations that are 180 degrees apart, corresponding to the positions of the liquid chambers 5 formed between the outer cylindrical member 2 and the rubber elastic body 4. Therefore, the liquid chambers 5 communicate with the outside through the communication holes 2C.

[0017] The rubber elastic body 4 is interposed between the outer cylindrical member 2 and the inner cylindrical member 3 when they are attached to the mold, and elastically connects the outer cylindrical member 2 and the inner cylindrical member 3. The rubber elastic body 4 has, at a portion facing the outer cylindrical member 2, two recesses 4A recessed toward the inner cylindrical member 3 near the center in the axial direction of the outer cylindrical member 2, and two grooves 4B connecting the two recesses 4A. Each recess 4A and the inner circumferential surface 2A of the outer cylindrical member 2 form a liquid chamber 5, and each groove 4B and the inner circumferential surface 2A of the outer cylindrical member 2 form an orifice flow path 6.

[0018] A hydraulic fluid L, such as an ethylene glycol solution, is poured into the fluid chamber 5 and the orifice flow path 6, and a rivet 7 having sealing properties is inserted into the communication hole 2C to seal it.

[0019] As shown in Fig. 4, in the manufacturing method of the liquid seal bushing 1, first, a core 8 for forming the liquid chamber 5 and the orifice flow path 6 is formed inside the outer cylindrical member 2 (core forming step: S1). As shown in Fig. 5, the core 8 is formed by placing a core forming die 9 for forming the core 8 in contact with the entire inner peripheral surface 2A of the outer cylindrical member 2. At this time, the core forming die 9 is placed inside the outer cylindrical member 2 in a state where it is heated to a predetermined temperature, which will be described later.

[0020] By disposing the core molding die 9 inside the outer cylindrical member 2, a space equivalent to the two liquid chambers 5 and the two orifice flow paths 6 is formed between the core molding die 9 and the inner peripheral surface 2A of the outer cylindrical member 2. At this time, the core molding die 9 is disposed so that the two communication holes 2C provided in the outer cylindrical member 2 are respectively positioned in the spaces forming the two liquid chambers 5.

[0021] Next, with the outer tubular member 2 and the core mold 9 heated to a predetermined temperature (described below), a polymer material for forming the core 8 is injected through the communicating hole 2C of the outer tubular member 2. This polymer material is, for example, a polymer material that hardens at high temperatures and fluidizes at low temperatures; in this case, it is adjusted to exhibit high rigidity at the molding temperature of the rubber elastomer 4 and to become fluid after the molded rubber elastomer 4 is cooled. An example of such a polymer material is a novel polymer hydrogel developed by a research group at the Graduate School of Advanced Life Science, Hokkaido University (published in Advance Materials, published November 18, 2019).

[0022] When injecting the polymer material, the outer tube member 2 is heated to the aforementioned predetermined temperature, which is equal to or higher than the molding temperature of the rubber elastic body 4 and allows the polymer material to harden. After the injected polymer material has hardened, the core molding die 9 is removed. At this time, as shown in Figure 6, the injected polymer material is expelled from the communicating hole 2C of the outer tube member 2 and hardens, fixing the core 8 to the outer tube member 2, and the core 8, made of hardened polymer material, is provided inside the outer tube member 2 as an integral part of the outer tube member 2.

[0023] Next, the outer cylindrical member 2 and the inner cylindrical member 3, each having the core 8 attached thereto, are placed in a rubber elastic body molding die for molding the rubber elastic body 4, and molten rubber is injected between the outer cylindrical member 2 and the inner cylindrical member 3, each having the core 8 attached thereto, and then cooled to mold the rubber elastic body 4 (rubber elastic body molding step: S2). As a result, a liquid chamber 5 and an orifice flow path 6 are formed between the outer cylindrical member 2 and the rubber elastic body 4, and the inner peripheral surface 2A of the outer cylindrical member 2 and the outer peripheral surface of the inner cylindrical member 3 are vulcanization bonded together. At room temperature when the rubber elastic body 4 is molded, the core 8 is softened and in a sol-like state.

[0024] Next, for example, air is injected from one of the communication holes 2C, and the polymer material that has been turned into a solubilized solution in the liquid chamber 5 and the orifice flow path 6 is discharged from the other of the communication holes 2C (discharge step: S3). As a result, the liquid chamber 5 and the orifice flow path 6 become empty spaces.

[0025] Finally, the hydraulic fluid L is poured through the communication holes 2C, and the two communication holes 2C are sealed by inserting rivets 7, thereby completing the liquid seal bushing 1 (hydraulic fluid pouring step: S4).

[0026] According to the liquid-sealed bushing 1 of this embodiment, the liquid chamber 5 and orifice flow path 6 formed between the outer tube member 2 and the rubber elastic body 4 interposed between the outer tube member 2 and the inner tube member 3 are directly joined and sealed at both ends in the axial direction of the outer tube member 2, making it possible to seal the rubber elastic body 4 and the outer tube member 2 by vulcanization bonding caused by molding the rubber elastic body 4.

[0027] Therefore, unlike conventional liquid-sealed bushings, there is no need for a ring for joining the outer cylindrical member to a molded rubber member in which the inner cylindrical member and the rubber elastic body are integrated, or for a restricting passage component for forming a restricting passage, which makes it possible to reduce the number of constituent parts and keep costs low, and also improves manufacturability by reducing the number of manufacturing steps, making it possible to further reduce costs.

[0028] Furthermore, according to the manufacturing method of the liquid-sealed bushing 1 of this embodiment, the core 8, which is placed inside the outer tube member 2 together with the inner tube member 3 when molding the rubber elastic body 4, is formed from a polymeric material that hardens at the molding temperature of the rubber elastic body 4.Therefore, by placing the core 8 inside the outer tube member 2 and molding the rubber elastic body 4, it is possible to prevent unvulcanized rubber from entering the areas that form the liquid chamber 5 and orifice flow path 6 between the rubber elastic body 4 and the outer tube member 2.

[0029] Furthermore, the polymer material forming the core 8 softens when cooled after molding the rubber elastic body 4, so it is possible to easily form the liquid chamber 5 and the orifice flow path 6 between the rubber elastic body 4 and the outer cylindrical member 2 simply by discharging the softened polymer material. Furthermore, since the liquid seal bushing 1 can be manufactured simply by molding the rubber elastic body 4 using the outer cylindrical member 2, the inner cylindrical member 3, and the core 8, it is possible to keep the number of parts used to a minimum. This makes it possible to manufacture the liquid seal bushing 1 easily while keeping costs low.

[0030] Furthermore, the softened polymeric material that formed the core 8 is discharged from the communication hole 2C that is provided in the outer cylindrical member 2 and connects the liquid chamber 5 to the outside, so that the softened polymeric material in the liquid chamber 5 can be more reliably discharged to the outside from the communication hole 2C. At this time, air is injected through one of the two communication holes 2C and the polymeric material is discharged from the other communication hole 2C, so that the polymeric material can be easily discharged by the air.

[0031] In the above embodiment, an example has been described in which the softened polymer material in the liquid chamber 5 and the orifice flow path 6 is discharged by air, but the present invention is not limited to this. For example, if the hydraulic fluid L is injected through one of the two communication holes 2C and the injected hydraulic fluid L pushes out and discharges the softened polymer material from the other communication hole 2C, the work efficiency can be further improved.

[0032] Furthermore, if a polymeric material that hardens in high temperature ranges and becomes fluid in low temperature ranges can be used as the working fluid L, then by forming the core 8 from the working fluid L, there is no need for a discharge step of discharging the softened polymeric material after molding the rubber elastic body 4, and the liquid-sealed bushing 1 can be manufactured more easily and in a shorter time.

[0033] In the above embodiment, an example in which two liquid chambers 5 are provided has been described, but three or more liquid chambers may be provided.

[0034] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the gist of the present invention. The present invention covers all technical matters included in the technical ideas described in the claims. The above-described embodiments are preferred examples, but a person skilled in the art can realize various alternatives, modifications, variations, or improvements from the contents disclosed in this specification, and these are included in the technical scope described in the appended claims. [Explanation of symbols]

[0035] 1 Liquid-sealed bushing 2. Outer cylinder member 2A Inner surface 2B Outer surface 2C communication hole 3. Inner cylinder member 3A hollow hole 4. Rubber elastic body 4A Recess 4B Groove 5 Liquid chamber 6 Orifice flow path 7 Rivets 8 Core 9 Core mold L Hydraulic fluid

Claims

1. an outer cylindrical member; an inner cylindrical member disposed in a hollow portion of the outer cylindrical member; a rubber elastic body interposed between the outer cylindrical member and the inner cylindrical member, a plurality of fluid chambers, spaced apart in a circumferential direction between the outer cylindrical member and the rubber elastic body, each containing a hydraulic fluid; an orifice flow path that connects the plurality of liquid chambers; the rubber elastic body and the outer cylindrical member are directly joined and sealed at both ends of the plurality of liquid chambers and the orifice flow path in the axial direction of the outer cylindrical member; A liquid-sealed bushing characterized by the above.

2. 2. The liquid-sealed bushing according to claim 1, The outer cylinder member has a communication hole that connects the liquid chamber with the outside. A liquid-sealed bushing characterized by the above.

3. 3. The liquid-sealed bushing according to claim 2, the communication hole is provided in each of the at least two liquid chambers; A liquid-sealed bushing characterized by the above.

4. A method for manufacturing the liquid-sealed bushing according to claim 1, a core forming step of forming a core for forming the liquid chamber and the orifice flow path from a material that is hardened at a molding temperature of the rubber elastic body and that softens after molding of the rubber elastic body; a rubber elastic body molding step of molding the inner cylindrical member and the core disposed inside the outer cylindrical member to form the rubber elastic body; having A method for manufacturing a liquid-sealed bushing.

5. 5. The method for manufacturing a liquid-sealed bushing according to claim 4, a discharging step of discharging the softened core, A method for manufacturing a liquid-sealed bushing.

6. 6. The method for manufacturing a liquid-sealed bushing according to claim 5, After the core is softened, it is discharged from a communication hole that communicates the liquid chamber of the outer cylindrical member with the outside. A method for manufacturing a liquid-sealed bushing.

7. 7. The method for manufacturing a liquid-sealed bushing according to claim 6, A plurality of the communication holes are provided, The working fluid is injected through one of the plurality of communication holes, and the softened core is discharged through a communication hole different from the communication hole into which the working fluid is injected. A method for manufacturing a liquid-sealed bushing.

8. 5. The method for manufacturing a liquid-sealed bushing according to claim 4, The core is formed by the hydraulic fluid. A method for manufacturing a liquid-sealed bushing.

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