Liquid-sealed bushing manufacturing method

Abstract

To provide a manufacturing method of a liquid sealing bush which can obtain the liquid sealing bush more easily.SOLUTION: A liquid sealing bush manufacturing method is used to manufacture a liquid sealing bush 1 and includes: a vulcanization step in which a no-liquid bush 1' is obtained by vulcanization molding; and a working fluid injection step in which working fluid 5 is injected into the no-liquid bush. The no-liquid bush includes an inner cylinder 2, an outer cylinder 3, and a body rubber 4 connecting the inner cylinder with the outer cylinder. An inner peripheral surface of the body rubber has: a pair of joint parts 41 which is joined at their entire peripheries to an outer peripheral surface and / or an axial end surface of the inner cylinder on both axial sides; and a non-joint part 42 which extends between the pair of joint parts and is not joined to the inner cylinder. In the working fluid injection step, the working fluid is injected into a gap G between the non-joint part of the body rubber and the inner cylinder in the non-liquid bush to expand the gap with the working fluid and thereby form a liquid chamber 6 to obtain the liquid sealing bush.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a liquid-sealed bush.

Background Art

[0002] Conventionally, there is a method for manufacturing a liquid-sealed bush by integrally vulcanization-molding an inner cylinder, a ring, and rubber therebetween, fitting a member for sealing a liquid chamber thereto, and then inserting these components into an outer cylinder or the like (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0004] However, the conventional method for manufacturing a liquid-sealed bush is complicated, and there is room for simplification.

[0005] An object of the present invention is to provide a method for manufacturing a liquid-sealed bush that allows the liquid-sealed bush to be obtained more easily.

Means for Solving the Problem

[0006] [1] A method for manufacturing a liquid-sealed bush for producing the liquid-sealed bush, comprising: a vulcanization step of obtaining a liquid-free bush by vulcanization molding; a working fluid injection step of injecting a working fluid into the liquid-free bush; including; the liquid-free bush includes: an inner cylinder; an outer cylinder; a main body rubber that connects the inner cylinder and the outer cylinder to each other; and; the inner peripheral surface of the main body rubber is A pair of joints are joined to the outer circumferential surface and / or axial end face of the inner cylinder on both sides in the axial direction, A non-jointed portion extends between the pair of jointed portions and is not joined to the inner cylinder, It has, A method for manufacturing a liquid-sealed bush, wherein in the hydraulic fluid injection step, the hydraulic fluid is injected into the gap between the non-jointed portion of the main body rubber and the inner cylinder of the liquid-free bush, and a liquid chamber is formed by expanding the gap with the hydraulic fluid to obtain a liquid-sealed bush. This makes it easier to obtain liquid-filled bushings.

[0007] [2] The outer cylinder has an outer cylinder through hole that penetrates the outer cylinder radially, The liquid-sealed bush manufacturing method according to [1], wherein in the hydraulic fluid injection step, while the gap is expanded with the hydraulic fluid, the portion of the main body rubber facing the outer cylinder through hole is pushed into the outer cylinder through hole by the hydraulic fluid. This makes it easier to inflate the liquid chamber.

[0008] [3] The outer cylinder through hole is A pair of wide holes spaced apart from each other in the circumferential direction, The pair of wide holes are connected to each other, and a narrow hole is provided which has a narrower width in the axial direction than the pair of wide holes. It has, The liquid-sealed bush manufacturing method according to [2], wherein in the hydraulic fluid injection step, a pair of main fluid chambers are formed between the portion of the main body rubber facing the pair of wide holes and the inner cylinder, and an orifice connecting the pair of main fluid chambers is formed between the portion of the main body rubber facing the narrow hole and the inner cylinder. This allows for the formation of a pair of main fluid chambers and an orifice connecting them.

[0009] [4] The liquid-filled bush manufacturing method according to any one of [1] to [3], wherein the outer surface of the inner cylinder has a bulge-shaped portion that protrudes toward the outer circumference. In this case, higher spring stiffness can be achieved with respect to displacement in the direction perpendicular to the axis.

[0010] [5] The pair of joints of the main body rubber are joined to the outer surface of the inner cylinder, excluding the bulge-shaped portion, and / or to the axial end face of the inner cylinder, over the entire circumference. The liquid-sealed bush manufacturing method according to [4], wherein the non-jointed portion of the main body rubber is not joined to the bulge-shaped portion of the inner cylinder. In this case, the spring stiffness with respect to displacement in the twisting direction can be further reduced.

[0011] [6] The liquid-sealed bush manufacturing method according to [2] or [3], further comprising a spacer member fitting step, after the working fluid injection step, of fitting a spacer member into the outer cylinder through hole to thereby seal the outer cylinder through hole. This prevents deformation of the outer cylinder of the liquid-sealing bush when the liquid-sealing bush is pressed into the external cylindrical member. [Effects of the Invention]

[0012] This invention provides a method for manufacturing liquid-sealed bushings that allows for easier acquisition of liquid-sealed bushings. [Brief explanation of the drawing]

[0013] [Figure 1] This is a diagram illustrating the vulcanization process in a liquid-filled bush manufacturing method according to one embodiment of the present invention, and is an axial cross-sectional view schematically showing a liquid-free bush obtained by the vulcanization process. [Figure 2] This is an axial cross-sectional view of the fluid-free bushing shown in Figure 1, but with a different cross-section than that shown in Figure 1. [Figure 3] This is a schematic side view showing the liquid-free bushing in Figure 1 when viewed radially. [Figure 4] FIG. 3 is a side view schematically showing the no-liquid bush of FIG. 3 when viewed in the radial direction from an angle different from that of FIG. 3. [Figure 5] FIG. 2 is a drawing for explaining a joined portion and a non-joined portion in the inner cylinder of FIG. 1. [Figure 6] FIG. 6(a) is an axial sectional view schematically showing the no-liquid bush immediately after the vulcanization step, FIG. 6(b) is an axial sectional view schematically showing a state where the no-liquid bush has cooled after the state of FIG. 6(a), and FIG. 6(c) is an axial sectional view schematically showing the no-liquid bush after the drawing step is performed following the state of FIG. 6(b). [Figure 7] FIG. 7 is a drawing for explaining a working liquid injection step in the method for manufacturing a liquid-sealed bush according to one embodiment of the present invention, and is an axial sectional view schematically showing the liquid-sealed bush obtained by performing the working liquid injection step on the no-liquid bush of FIGS. 1 to 4. [Figure 8] FIG. 8 is an axial sectional view showing the liquid-sealed bush of FIG. 7 with a cross section different from that of FIG. 7. [Figure 9] FIG. 9 is a side view schematically showing the liquid-sealed bush of FIG. 7 when viewed in the radial direction. [Figure 10] FIG. 10 is a side view schematically showing the liquid-sealed bush of FIG. 9 when viewed in the radial direction from an angle different from that of FIG. 9. [Figure 11] FIG. 11 is a side view schematically showing the liquid-sealed bush after the spacer member fitting step is performed following the state of FIG. 9, when viewed in the radial direction. [Figure 12] FIG. 12 is a side view schematically showing the liquid-sealed bush of FIG. 11 when viewed in the radial direction from an angle different from that of FIG. 11. [Figure 13] FIG. 13 is a perspective view schematically showing the spacer member of FIGS. 11 to 12. [Figure 14] FIG. 14 is an axial sectional view schematically showing, together with an outer cylindrical member, the liquid-sealed bush that is press-fitted into the outer cylindrical member after the states of FIGS. 11 to 12. [Figure 15]This is an axial cross-sectional view showing the liquid-sealed bush and the external cylindrical member from Figure 14, but with a different cross-section than that of Figure 14. [Figure 16] Figure 14 is a cross-sectional view perpendicular to the axis, showing the liquid-sealed bush and the external cylindrical member along line AA in Figure 14. [Modes for carrying out the invention]

[0014] The liquid-filled bush obtained by the liquid-filled bush manufacturing method according to the present invention is preferably used in, for example, vehicle suspension systems (e.g., MacPherson strut type suspension systems), and is preferably used in, for example, link mechanisms (suspension arms, etc.) of vehicle suspension systems. The following describes an embodiment of the liquid-filled bush manufacturing method according to this invention, with reference to the drawings.

[0015] Figures 1 to 16 are diagrams illustrating a liquid-filled bush manufacturing method according to one embodiment of the present invention. The liquid-filled bush manufacturing method of this embodiment is used to manufacture a liquid-filled bush 1 as shown in Figures 14 to 16, for example. The liquid-filled bush 1 in the example of Figures 14 to 16 is configured to be suitably used in a vehicle suspension system (e.g., a MacPherson strut suspension system), and is configured to be suitably used in, for example, a link mechanism (suspension arm, etc.) of a vehicle suspension system. More specifically, the liquid-filled bush 1 in the example of Figures 14 to 16 is configured to be press-fitted into the inner circumferential surface of an external cylindrical member A1 (e.g., cylindrical member A1 of a suspension arm A (Figure 16) of a vehicle suspension system). The axial direction of the liquid-filled bush 1 in the example of Figures 14 to 16 is oriented to be substantially horizontal. However, the liquid-filled bush 1 in each example described herein may be used for any application other than those described above. Furthermore, the axial direction of the liquid-filled bush 1 may be oriented in any direction.

[0016] The liquid-sealed bush manufacturing method of this embodiment includes at least a vulcanization step and a working fluid injection step. In the vulcanization process, a liquid-free bush 1' (Figures 1-4) is obtained by vulcanization molding. In the hydraulic fluid injection process, hydraulic fluid 5 is injected into the fluid-free bush 1', thereby obtaining the fluid-sealed bush 1 (Figures 7 to 10). The fluid-sealed bush 1 has a structure in which hydraulic fluid 5 is sealed inside the fluid-free bush 1'. Therefore, unless otherwise specified, the fluid-sealed bush 1 has the same configuration as the fluid-free bush 1'. The following provides a more detailed explanation of these points. In this specification, the liquid-free bush 1' and the liquid-filled bush 1 may be simply referred to as "bush (1', 1)". Furthermore, in order to facilitate understanding of the orientation of bushes 1' and 1 shown in each drawing, this specification defines an XYZ Cartesian coordinate system fixed to bushes 1' and 1, as shown in each drawing. The X-axis is parallel to the central axis O3 of bushes 1' and 1. Also, in this specification, as shown in each drawing, one side in the Y-axis direction is referred to as the "first Y-axis side (Y1)," and the other side in the Y-axis direction is referred to as the "second Y-axis side (Y2)."

[0017] In this specification, when describing bushes 1', 1, for convenience, unless otherwise specified, the structure described will be that of bushes 1', 1 when no input is applied to them and they are in a normal, stationary state, as shown in each drawing.

[0018] Figures 1 to 4 schematically show the liquid-free bush 1' obtained by the vulcanization process. Figure 1 is an axial cross-sectional view schematically showing the liquid-free bush 1' through the central axis O3 and parallel to the XZ plane. Figure 2 is an axial cross-sectional view of the liquid-free bush 1' of Figure 1 through the central axis O3 and parallel to the XY plane. Figure 3 is a schematic side view schematically showing the liquid-free bush 1' of Figure 1 viewed radially from the first side Y1 in the Y-axis direction toward the second side Y2 in the Y-axis direction. Figure 4 is a schematic side view schematically showing the liquid-free bush 1' of Figure 3 viewed radially from the second side Y2 in the Y-axis direction toward the first side Y1 in the Y-axis direction. The fluid-free bushing 1' comprises an inner cylinder 2, an outer cylinder 3, and a rubber body 4 (Figures 1 to 4). The inner circumferential surface of the rubber body 4 in the fluid-free bushing 1' has a pair of joint portions 41 and a non-joint portion 42 (Figures 1 to 2).

[0019] Examples of materials that make up the inner cylinder 2 include metal and / or resin.

[0020] The outer cylinder 3 is located on the outer circumference of the inner cylinder 2. The inner cylinder 2 is arranged coaxially with the outer cylinder 3; in other words, the central axis O2 of the inner cylinder 2 coincides with the central axis O3 of the outer cylinder 3.

[0021] In this specification, the central axis O3 of the outer cylinder 3 is considered to be the central axis O3 of bushes 1', 1. In this specification, unless otherwise specified, the direction parallel to the central axis O3 of bushes 1', 1 is referred to as the "axial direction," the side of bushes 1', 1 that is farther from the center in the axial direction is referred to as the "outer side in the axial direction," the side of bushes 1', 1 that is closer to the center in the axial direction is referred to as the "inner side in the axial direction," the direction perpendicular to the central axis O3 of bushes 1', 1 is referred to as the "perpendicular direction," the side of bushes 1', 1 that is closer to the central axis O3 is referred to as the "inner circumference side," the side of bushes 1', 1 that is farther from the central axis O3 is referred to as the "outer circumference side," the circumferential direction centered on the central axis O3 of bushes 1', 1 is referred to as the "circumferential direction," and the radial direction centered on the central axis O3 of bushes 1', 1 is referred to as the "radial direction."

[0022] The main rubber body 4 is made of rubber. The rubber constituting the main rubber body 4 may be, for example, self-lubricating rubber or other rubber with a low coefficient of friction. The main rubber body 4 is located between the inner cylinder 2 and the outer cylinder 3 in the radial direction. The main rubber body 4 connects the inner cylinder 2 and the outer cylinder 3 to each other. The main rubber body 4 extends around the entire circumference between the inner cylinder 2 and the outer cylinder 3, and thus forms a cylindrical shape.

[0023] Preferably, the outer surface of the main rubber body 4 is joined to the inner surface of the outer cylinder 3 in the portion where it is in contact with the inner surface of the outer cylinder 3. The joining between the main rubber body 4 and the outer cylinder 3 may be done by any method, such as vulcanization bonding and / or bonding via an adhesive.

[0024] As described above, the inner circumferential surface of the main rubber body 4 has a pair of joint portions 41 and a non-joint portion 42 (Figures 1-2).

[0025] The pair of joint portions 41 on the inner circumferential surface of the main rubber body 4 are located on both sides in the axial direction with respect to the axial center of the bush 1' (the same axial position as the axial center of the outer cylinder 3), and are joined to the outer circumferential surface of the inner cylinder 2 over its entire circumference (Figures 1-2). In addition, in the examples described herein, the case is not limited to the case in which each of the pair of joints 41 is joined only to the outer circumferential surface of the inner cylinder 2, as shown in the examples in Figures 1 and 2. Although not shown, each of the pair of joints 41 may be joined only to the axial end face of the inner cylinder 2, or it may be joined to both the outer circumferential surface and the axial end face of the inner cylinder 2.

[0026] The non-joint portion 42 on the inner circumferential surface of the main rubber 4 extends between the pair of joint portions 41 (Figures 1-2). The non-joint portion 42 is not joined to the inner cylinder 2 (specifically, the outer circumferential surface of the inner cylinder 2). The non-joint portion 42 is radially opposite to the inner cylinder 2 (specifically, the outer circumferential surface of the inner cylinder 2). The non-joint portion 42 may or may not be in contact with the inner cylinder 2 (specifically, the outer circumferential surface of the inner cylinder 2). The non-joint portion 42 is located in the axial center of the bush 1' and is located on the axial center of the bush 1'. It is preferable that the non-joint portion 42 extends around the entire circumference. In the liquid-free bush 1', the gap G between the non-joint portion 42 of the main rubber 4 and the inner cylinder 2 may be almost or completely compressed.

[0027] As shown in Figures 1-2 and 5, in this specification, the portion of the inner cylinder 2's surface that is joined to the joint portion 41 of the main body rubber 4 is referred to as the "joint portion 21," and the portion that is not joined to the non-joint portion 42 of the main body rubber 4 but faces the non-joint portion 42 is referred to as the "non-joint portion 22." In the example shown, the joint portion 21 is located on the outer circumferential surface of the inner cylinder 2. In addition, in the examples described herein, the outer circumferential surface of the inner cylinder 2 is not limited to the case shown in Figures 1-2 and 5, where the inner cylinder 2 has a pair of joints 21 located on both sides in the axial direction with respect to the axial center of the bush 1' and a non-jointed portion 22 between them. Although not shown, the inner cylinder 2 may have a pair of joints 21 located on both sides in the axial direction with respect to the axial center of the bush 1', and the outer circumferential surface of the inner cylinder 2 may have a non-jointed portion 22. Alternatively, both the outer circumferential surface and the axial end faces of the inner cylinder 2 may have a pair of joints 21 located on both sides in the axial direction with respect to the axial center of the bush 1', and the outer circumferential surface of the inner cylinder 2 may have a non-jointed portion 22.

[0028] The joining between the main body rubber 4 and the inner cylinder 2 at the joints 41 and 21 may be done by any method, such as vulcanization bonding and / or bonding via an adhesive. Examples of methods for forming the joints 41, 21 and the non-joints 42, 22 will be described in more detail later.

[0029] For example, in the injection process, it is preferable to inject unvulcanized rubber to constitute the main body rubber 4 into a mold in which the inner cylinder 2 and outer cylinder 3 are set, and then in the vulcanization process, to vulcanize the liquid-free bush 1' using the same mold.

[0030] In the hydraulic fluid injection process following the vulcanization process, hydraulic fluid 5 is injected into the gap G between the non-jointed portion 42 of the main rubber 4 and the non-jointed portion 22 of the inner cylinder 2 in the fluid-free bush 1', and a liquid chamber 6 is formed by expanding the gap G with the hydraulic fluid 5, thereby obtaining a liquid-sealed bush 1 (Figures 7 to 10). Figures 7 to 10 schematically show the liquid-sealed bush 1 obtained after the working fluid injection process (and the plug insertion process described later). Figure 7 is an axial cross-sectional view schematically showing the liquid-sealed bush 1 with a cross section passing through the central axis O3 and parallel to the XZ plane. Figure 8 is an axial cross-sectional view of the liquid-sealed bush 1 of Figure 7 with a cross section passing through the central axis O3 and parallel to the XY plane. Figure 9 is a schematic side view schematically showing the liquid-sealed bush 1 of Figure 7 viewed radially from the first side Y1 in the Y-axis direction toward the second side Y2 in the Y-axis direction. Figure 10 is a schematic side view schematically showing the liquid-sealed bush 1 of Figure 9 viewed radially from the second side Y2 in the Y-axis direction toward the first side Y1 in the Y-axis direction. Before performing the hydraulic fluid injection process, an injection hole H is formed in the fluid-free bush 1' (Figures 2 and 4). The injection hole H connects the gap G between the non-joint portion 22 of the inner cylinder 2 and the non-joint portion 42 of the main rubber body 4 to the outside of the fluid-free bush 1'. As shown in the examples in Figures 2 and 4, the injection hole H may pass through the outer cylinder 3 and the main rubber body 4 of the fluid-free bush 1' between the gap G and the outside of the fluid-free bush 1'. In this case, the method for forming the injection hole H in advance can be arbitrary, but for example, a through hole may be formed in advance at the corresponding location of the outer cylinder 3, and a projection for forming the injection hole H may be provided on the mold used during the injection process and vulcanization process. In the hydraulic fluid injection process, hydraulic fluid 5 is injected from the outside through the injection hole H into the gap G between the non-joint portion 22 of the inner cylinder 2 and the non-joint portion 42 of the main body rubber 4 (Figures 7-8). The liquid chamber 6 formed by expanding the gap G with hydraulic fluid 5 is partitioned by the non-joint portion 42 of the main body rubber 4 and the non-joint portion 22 of the inner cylinder 2 in the liquid-sealing bush 1, and is filled with hydraulic fluid 5. In the hydraulic fluid injection process, it is preferable to inject the hydraulic fluid 5 while applying pressure.

[0031] The working fluid 5 consists of, for example, ethylene glycol, silicone oil, etc.

[0032] It is preferable to perform the plug insertion step after the hydraulic fluid injection step. When performing the plug insertion process, as shown in Figures 8 and 10, the plug P is inserted into the injection hole H from the outside of the liquid-sealing bush 1 to seal the injection hole H. This prevents the working fluid 5 from leaking out. However, after the working fluid injection process, the injection hole H may be sealed by other means.

[0033] In this embodiment, as described above, in the vulcanization process, a liquid-free bush 1' is obtained having a pair of joint portions 41 on both sides in the axial direction and a non-joint portion 42 between them on the inner circumferential surface of the main body rubber 4. In the subsequent hydraulic fluid injection process, hydraulic fluid 5 is injected into the gap G between the non-joint portion 42 of the main body rubber 4 and the non-joint portion 22 of the inner cylinder 2 in the liquid-free bush 1', and a liquid chamber 6 is formed by expanding the gap G with the hydraulic fluid 5, thereby obtaining a liquid-sealed bush 1. Since the pair of joint portions 41 on both sides of the non-joint portion 42 of the main body rubber 4 are joined to the inner cylinder 2 around the entire circumference, the gap G between the non-joint portion 22 of the inner cylinder 2 and the non-joint portion 42 of the main body rubber 4, and thus the liquid chamber 6, becomes a sealed space sealed by the pair of joint portions 41 on both sides. Therefore, it is possible to suppress leakage of hydraulic fluid 5 from between the main body rubber 4 and the inner cylinder 2 without requiring any further members to seal the gap G and thus the liquid chamber 6. Therefore, the process of assembling the additional components becomes unnecessary, making it easier to obtain the liquid-sealed bush 1. Furthermore, the number of parts in the liquid-sealed bush 1 can be reduced. Thus, it becomes possible to reduce both time and cost. Furthermore, in this embodiment, as described above, in the liquid-sealed bush 1, the main body rubber 4 is joined to the inner cylinder 2 around its entire circumference at a pair of joints 41 on both sides in the axial direction, while the non-jointed portion 42 between the pair of joints 41 is not joined to the inner cylinder 2 (Figures 7-8). Therefore, when the inner cylinder 2 is displaced relative to the outer cylinder 3 in a torsional direction (the direction in which the inner cylinder 2 rotates circumferentially relative to the outer cylinder 3) or a twisting direction (the direction in which the central axis O2 of the inner cylinder 2 tilts relative to the central axis O3 of the outer cylinder 3), the main body rubber 4 is fixed on the inner cylinder 2 at a pair of joints 21 on both sides in the axial direction, but can move relatively freely relative to the inner cylinder 2 at the non-jointed portion 22 between them. Therefore, during torsional or twisting displacement, the portion of the main body rubber 4 near the pair of joints 41 contributes to the spring rigidity, but the portion of the main body rubber 4 near the non-jointed portion 42 contributes little to or no to the spring rigidity. Therefore, compared to a case where the main rubber body 4 is joined to the inner cylinder 2 over its entire surface, the area of ​​the part of the main rubber body 4 joined to the inner cylinder 2 is smaller, which reduces the rigidity in the torsional and twisting directions, and consequently makes the inner cylinder 2 more susceptible to torsional and twisting relative to the outer cylinder 3. This improves the performance as a liquid-filled bushing for a vehicle's suspension system. Furthermore, in each example described herein, the presence of the non-jointed portion 42 of the main rubber 4 does not affect the displacement in the direction perpendicular to the axis. Therefore, when the inner cylinder 2 is displaced in the direction perpendicular to the outer cylinder 3, the main rubber 4 can exhibit spring rigidity equal to or greater than that of the main rubber 4 if it were joined to the inner cylinder 2 across its entire surface, and consequently, it can exhibit good performance as a liquid-filled bushing for a vehicle suspension system.

[0034] The formation of the joint portion 41 and the non-joint portion 42 in the liquid-free bush 1' is preferably carried out during the vulcanization process. One method for forming the joint portion 41 and the non-joint portion 42 in the vulcanization process is as follows. First, in the adhesive application process prior to the vulcanization process, the portion of the inner cylinder 2 surface that will become the non-joint portion 22 is masked, and then adhesive is applied to the portion of the inner cylinder 2 surface that will become the joint portion 21. This prevents adhesive from being applied to the portion of the inner cylinder 2 surface that will become the non-joint portion 22. After that, the masking is removed. Then, in the injection process, unvulcanized rubber to constitute the main body rubber 4 is injected into a mold in which the inner cylinder 2 and outer cylinder 3 are set, and then, in the vulcanization process, the liquid-free bush 1' is vulcanized using the same mold. In this case, during the vulcanization process, the main body rubber 4 is joined to the portion of the inner cylinder 2 surface to which adhesive has been applied, forming the joint portion 41, while the masked portion of the inner cylinder 2 surface (i.e., the portion to which adhesive has not been applied) is not joined, forming the non-joint portion 42. Another method for forming the joint portion 41 and the non-joint portion 42 in the vulcanization process is as follows. First, in the adhesive sheet application process prior to the vulcanization process, an adhesive sheet is applied to the portion of the inner cylinder 2's surface that will become the joint portion 21. At this time, the adhesive sheet is not applied to the portion of the inner cylinder 2's surface that will become the non-joint portion 22. Subsequently, in the injection process, unvulcanized rubber for forming the main body rubber 4 is injected into a mold in which the inner cylinder 2 and outer cylinder 3 are set, and then, in the vulcanization process, the liquid-free bush 1' is vulcanized using the same mold. In this case, during the vulcanization process, the main body rubber 4 is joined to the portion of the inner cylinder 2's surface to which the adhesive sheet has been applied, forming the joint portion 41, while the portion of the inner cylinder 2's surface to which the adhesive sheet has not been applied is not joined, forming the non-joint portion 42. For example, the adhesive sheet described in Japanese Patent No. 4681634 may be used. Another method for forming the joint portion 41 and the non-joint portion 42 in the vulcanization process is as follows. First, in the surface processing process before the vulcanization process, the portion of the inner cylinder 2 surface that will become the joint portion 21 is surface-processed with a laser, thereby forming a number of micro-grooves in that portion of the inner cylinder 2. The portion of the inner cylinder 2 surface that will become the non-joint portion 22 is not surface-processed. Subsequently, in the injection process, unvulcanized rubber to constitute the main body rubber 4 is injected into a mold in which the inner cylinder 2 and outer cylinder 3 are set, and then, in the vulcanization process, the liquid-free bush 1' is vulcanized using the mold. In this case, during the vulcanization process, the main body rubber 4 enters the micro-grooves in the surface-processed portion of the inner cylinder 2 surface and is joined to that portion by the anchoring effect, forming the joint portion 41, while the portion of the inner cylinder 2 surface that has not been surface-processed is not joined, forming the non-joint portion 42. For this surface treatment, for example, those described in Japanese Patent Publication No. 2020-116862 and Japanese Patent No. 6489908 may be used. However, methods other than those described above may be used to form the joint portion 41 and the non-joint portion 42.

[0035] Figure 6(a) is a schematic axial cross-sectional view of the liquid-free bush 1' immediately after the vulcanization process, and Figure 6(b) is a schematic axial cross-sectional view of the liquid-free bush 1' after it has cooled down following the state shown in Figure 6(a). As shown in Figures 6(a) to 6(b), after the vulcanization process, the main rubber 4 of the liquid-free bush 1 gradually shrinks as it cools. During this time, the gap G between the non-jointed portion 42 of the main rubber 4 and the non-jointed portion 22 of the inner cylinder 2 may expand.

[0036] A throttling process (Figure 6(c)) may be performed after the vulcanization process and before the working fluid injection process. Figure 6(c) is a schematic axial cross-sectional view showing the liquid-free bush 1' after the throttling process has been performed after the liquid-free bush 1' has cooled down after the vulcanization process (Figure 6(b)). In the drawing process, the outer cylinder 3 is drawn radially inward, thereby reducing its diameter. This compresses the main body rubber 4, increasing its rigidity and thus improving its durability. The narrowing process (Figure 6(c)) can reduce the gap G between the non-jointed portion 42 of the main rubber body 4 and the non-jointed portion 22 of the inner cylinder 2. However, the pressing process does not need to be performed.

[0037] In bushes 1' and 1, it is preferable that the outer cylinder 3 has an outer cylinder through hole 33 that penetrates the outer cylinder 3 radially, as shown in Figures 1 to 4. In this case, during the hydraulic fluid injection process, while the gap G between the non-jointed portion 42 of the main body rubber 4 and the non-jointed portion 22 of the inner cylinder 2 is expanded by the hydraulic fluid 5, the portion 43 of the main body rubber 4 facing the outer cylinder through hole 33 is pushed outward toward the outer circumference towards the inner cylinder through hole 33 by the hydraulic fluid 5 (Figures 7 to 10). This makes it easier to expand the gap G and thus the liquid chamber 6, and also makes it possible to increase the amount of liquid in the liquid chamber 6. In this specification, "the portion 43 of the main body rubber 4 that faces the outer cylinder through hole 33" refers to the entire thickness of the portion of the main body rubber 4 that faces the outer cylinder through hole 33 in the radial direction (i.e., the portion extending from the outer peripheral surface to the inner peripheral surface in the radial direction). From the viewpoint of making it easier to inflate the gap G and, consequently, the liquid chamber 6 with the working fluid 5, it is preferable that at least a part (preferably the whole) of the inner circumferential surface of the portion 43 of the main body rubber 4 facing the outer cylinder through hole 33 constitutes a non-joint portion 42, as shown in the example in Figures 7 and 8. In this case, the portion 43 of the main body rubber 4 facing the outer cylinder through hole 33 is located between the outer cylinder through hole 33 and the non-joint portion 42 in the radial direction, so it becomes relatively easy to displace in the radial direction, and consequently, it becomes easier to inflate the gap G and, consequently, the liquid chamber 6, and it becomes possible to increase the amount of liquid in the liquid chamber 6. In addition, since the liquid chamber 6 is more easily formed on the inner circumferential side of the outer cylinder through hole 33, it becomes easier to form the liquid chamber 6 in the desired position (on the inner circumferential side of the outer cylinder through hole 33). The portion of the gap G that is not located on the inner circumference side of the outer cylinder through-hole 33 (i.e., the portion located in the area excluding the region occupied by the outer cylinder through-hole 33 in the axial and circumferential directions) is relatively less likely to expand, so a liquid chamber 6 is not substantially formed there and can be maintained in a nearly or completely closed state. From a similar viewpoint, it is preferable that the outer cylinder through hole 33 is located on the axial center of the outer cylinder 3, as shown in Figures 1 to 4.

[0038] In bushes 1' and 1, it is preferable that the outer cylinder through-hole 33 extends only over a portion of the circumferential direction, as shown in Figures 1 to 4, Figure 16, etc. In this case, the injection hole H for injecting the working fluid 5 may be provided in the area of ​​the bushes 1', 1 excluding the area occupied by the outer cylinder through hole 33 in the circumferential direction, as shown in Figures 4 and 16. From the viewpoint of improving the vibration damping effect of the liquid chamber 6, as shown in the examples in Figures 1 to 4 and Figure 16, the outer cylinder through hole 33 (and thus the liquid chamber 6) is preferably extended over an angular range of 90° or more around the central axis O3, more preferably over an angular range of 180° or more, and for example, more preferably over an angular range of 300° or more.

[0039] In bush 1', 1, as shown in Figures 1 to 4, the outer cylinder through hole 33 may have a pair of wide holes 331 and a narrow hole 332. The pair of wide holes 331 are spaced apart from each other in the circumferential direction. In the example shown, the pair of wide holes 331 are located at both ends in the circumferential direction of the outer cylinder through hole 33. The narrow hole portion 332 connects the pair of wide hole portions 331 and has a narrower axial width than each of the pair of wide hole portions 331. When the outer cylinder through-hole 33 is configured in this way, a fluid chamber 6 can be formed in the working fluid injection process, having a pair of main fluid chambers 61 and an orifice 62 connecting the pair of main fluid chambers 61 (Figures 7 to 10). More specifically, a pair of main fluid chambers 61 are formed between the portion 431 of the main body rubber 4 facing the pair of wide holes 331 and the non-joint portion 22 of the inner cylinder 2, and an orifice 62 is formed between the portion 432 of the main body rubber 4 facing the narrow hole 332 and the non-joint portion 22 of the inner cylinder 2. The orifice 62 is narrower in the axial direction than each of the pair of main fluid chambers 61. This allows for the formation of a pair of main fluid chambers 61 and an orifice 62 connecting them. Consequently, a vibration damping effect can be achieved due to the flow resistance of the working fluid 5 moving back and forth within the orifice 62. Furthermore, dynamic characteristics at a predetermined frequency can be obtained through fluid resonance within the orifice 62. The pair of wide holes 331 (and consequently the pair of main liquid chambers 61) may have the same or different widths in the axial direction. However, the shape of the outer cylinder through hole 33 can be arbitrary; for example, the outer cylinder through hole 33 may have a constant axial width along its entire length in the circumferential direction.

[0040] If the outer cylinder 3 has an outer cylinder through hole 33, it is preferable to perform the spacer member fitting process (Figures 11-12) after the working fluid injection process. Figure 11 is a schematic side view showing the liquid-sealed bush 1 after the spacer member fitting process has been performed, viewed radially from the first side Y1 in the Y-axis direction to the second side Y2 in the Y-axis direction, relative to the state after the working fluid injection process (Figure 9). Figure 12 is a schematic side view showing the liquid-sealed bush 1 of Figure 11 viewed radially from the second side Y2 in the Y-axis direction to the first side Y1 in the Y-axis direction. The axial and perpendicular cross-sectional views of the liquid-sealed bush 1 in the state shown in Figures 11 to 12 are almost the same as those shown in Figures 14 to 16. In the spacer member fitting process, the spacer member 7 is fitted into the outer cylinder through hole 33 of the outer cylinder 3, thereby closing the outer cylinder through hole 33. This allows the strength of the part of the outer cylinder 3 that is missing due to the outer cylinder through hole 33 to be compensated for by the spacer member 7. Therefore, deformation of the outer cylinder 3 of the liquid-sealed bush 1 can be effectively suppressed when the liquid-sealed bush 1 is press-fitted into the external cylindrical member A1 (for example, the cylindrical member A1 of the suspension arm A of a vehicle suspension system (Figure 16)). Figures 14 to 16 show the state after the liquid-sealed bush 1 has been press-fitted into the external cylindrical member A1 (for example, the cylindrical member A1 of the suspension arm A (Figure 16) of a vehicle's suspension system) after the spacer member fitting process. Figure 14 is an axial cross-sectional view schematically showing the liquid-sealed bush 1 and the external cylindrical member A1 in a cross section that passes through the central axis O3 and is parallel to the XZ plane. Figure 15 is an axial cross-sectional view showing the liquid-sealed bush 1 and the external cylindrical member A1 of Figure 14 in a cross section that passes through the central axis O3 and is parallel to the XY plane. Figure 16 is an axial cross-sectional view showing the liquid-sealed bush 1 and the external cylindrical member A1 of Figure 14 in a cross section along line AA of Figure 14. It is preferable that the spacer member 7 has a shape and dimensions that substantially match the shape of the outer cylinder through hole 33 of the outer cylinder 3. That is, in the spacer member fitting process, it is preferable that almost the entire outer cylinder through hole 33 is filled by the spacer member 7. In this example, as shown in Figure 13, the spacer member 7 extends only over a portion of the circumferential direction and has a roughly C-shape. In this example, the spacer member 7 has a pair of wide spacer portions 71 and a narrow spacer portion 72. The pair of wide spacer portions 71 are located at both ends of the spacer member 7 in the circumferential direction. The narrow spacer portion 72 connects the pair of wide spacer portions 71 and has a width in the axial direction that is narrower than the pair of wide spacer portions 71. The pair of wide spacer portions 71 are fitted into a pair of wide holes 331 of the outer cylinder through hole 33, and the narrow spacer portion 72 is fitted into a narrow hole 332 of the outer cylinder through hole 33. The spacer member 7 is preferably made of an elastic material, for example, metal or resin. This allows the spacer member fitting process to be performed more easily, as the spacer member 7 can be fitted into the outer cylinder through hole 33 in an expanded (increased diameter) state, and then reduced in diameter by restoring it after fitting. However, the spacer member fitting process does not need to be performed.

[0041] In bushes 1' and 1, it is preferable that the outer circumferential surface of the inner cylinder 2 has a bulge-shaped portion 23 that protrudes toward the outer circumferential side, as shown in Figures 1 to 2, Figure 5, etc. In this case, the portion of the inner circumferential surface of the main body rubber 4 that contacts the bulge-shaped portion 23 of the inner cylinder 2 will have a concave shape that is recessed toward the outer circumferential side to fit the bulge-shaped portion 23. It is preferable that the bulge-shaped portion 23 extends around the entire circumference in an annular shape. When the outer circumferential surface of the inner cylinder 2 has a bulge-shaped portion 23, the thickness of the main rubber 4 in the axial direction becomes relatively thinner in the portion of the main rubber 4 that faces the bulge-shaped portion 23 in the axial direction. As a result, the main rubber 4 can exhibit higher spring rigidity with respect to the relative displacement of the inner cylinder 2 in the axial direction. The outer circumferential surface of the inner cylinder 2 may have a bulge-shaped portion 23 and a pair of non-bulge-shaped portions 24 located on both sides of the bulge-shaped portion 23 in the axial direction and not having a bulge shape, as shown in the example in Figure 5. The non-bulge-shaped portions 24 are preferably configured to be linear (for example, cylindrical) along the axial direction, as shown in the example in Figure 5. Alternatively, although not shown in the illustration, the outer circumferential surface of the inner cylinder 2 may have only the bulge-shaped portion 23.

[0042] In bushes 1' and 1, as described above, when the outer circumferential surface of the inner cylinder 2 has a bulge-shaped portion 23, it is preferable that, as shown in Figures 1 to 2, Figure 5, etc., the pair of joint portions 41 of the main rubber 4 are joined to the portion of the outer circumferential surface of the inner cylinder 2 excluding the bulge-shaped portion 23 (i.e., the non-bulge-shaped portion 24) and / or the axial end face of the inner cylinder 2, and the non-joint portion 42 of the main rubber 4 is not joined to part or all of the bulge-shaped portion 23 of the inner cylinder 2 (i.e., part or all of the bulge-shaped portion 23 forms the non-joint portion 22). In this case, when the inner cylinder 2 is displaced in the twisting direction in the liquid-sealed bush 1, the non-joint portion 42 of the main rubber 4 moves more smoothly around the non-joint portion 22, which is made up of the bulge-shaped portion 23 of the inner cylinder 2. Therefore, the spring stiffness against displacement in the twisting direction can be further reduced.

[0043] As described above, if the outer surface of the inner cylinder 2 has a bulge-shaped portion 23, the bulge shape of the bulge-shaped portion 23 can be any shape as long as it protrudes outward. The bulge shape of the bulge-shaped portion 23 preferably includes a curved portion, as shown in Figures 1-2, Figure 5, etc. In this case, when the inner cylinder 2 is displaced in the twisting direction, the non-joint portion 42 of the main body rubber 4 can move more smoothly around the non-joint portion 22 made up of the bulge-shaped portion 23 of the inner cylinder 2. The bulge shape of the bulge-shaped portion 23 may consist only of a curved shape. The bulge shape of the bulge-shaped portion 23 is preferably a shape without sharp corners, as shown in Figures 1-2, 5, etc. In this case, when the inner cylinder 2 is displaced in the twisting direction, the non-joint portion 42 of the main body rubber 4 can move more smoothly around the non-joint portion 22 made up of the bulge-shaped portion 23 of the inner cylinder 2. The bulge shape of the bulge-shaped portion 23 is preferably such that it gradually moves towards the outer circumference as it approaches the axial center of the liquid-sealed bush 1, as shown in Figures 1-2, 5, etc. In this case, when the inner cylinder 2 is displaced in the twisting direction, the non-joint portion 42 of the main body rubber 4 can move more smoothly around the non-joint portion 22 made up of the bulge-shaped portion 23 of the inner cylinder 2. The bulge shape of the bulge portion 23 may be, for example, spherical. [Industrial applicability]

[0044] The liquid-filled bush obtained by the liquid-filled bush manufacturing method according to the present invention is preferably used in, for example, vehicle suspension systems (e.g., MacPherson strut type suspension systems), and is preferably used in, for example, link mechanisms (suspension arms, etc.) of vehicle suspension systems. [Explanation of Symbols]

[0045] 1: Liquid-filled bushing (bushing), 1': Fluid-free bushing (bushing), 2: Inner cylinder, 21: Joint, 22: Non-joint, 23: Bulge-shaped part, 24: Non-bulge-shaped part, 25: Inner circumference of inner cylinder, 26: Outer circumference of inner cylinder, 3: Outer cylinder, 33: Through hole in outer cylinder, 331: Wide hole section, 332: Narrow hole section, 4: Main body rubber, 41: Joint part, 42: Non-joint part, 43: Part facing the outer cylinder through hole, 431: Part facing the wide hole, 432: Part facing the narrow hole, 5: Working fluid, 6: Liquid chamber, 61: Main liquid chamber, 62: Orifice, 7: Spacer member, 71: Wide spacer section, 72: Narrow spacer section, H: injection hole, O2: Central axis of the inner cylinder, O3: Central axis of the outer cylinder (central axis of the bush), G: Gap, P: Plug, A: Suspension arm, A1: Cylindrical member

Claims

1. A method for manufacturing a liquid-sealed bush, A vulcanization process is used to obtain a liquid-free bush by vulcanization molding, A hydraulic fluid injection step involves injecting hydraulic fluid into the aforementioned fluid-free bush, Includes, The aforementioned fluid-free bushing is Inner cylinder and Outer cylinder and The main body rubber connects the inner cylinder and the outer cylinder, Equipped with, The inner circumferential surface of the aforementioned rubber body is A pair of joints are joined to the outer circumferential surface and / or axial end face of the inner cylinder on both sides in the axial direction, A non-jointed portion extends between the pair of jointed portions and is not joined to the inner cylinder, It has, A method for manufacturing a liquid-sealed bush, wherein in the hydraulic fluid injection step, the hydraulic fluid is injected into the gap between the non-jointed portion of the main body rubber and the inner cylinder of the liquid-free bush, and a liquid chamber is formed by expanding the gap with the hydraulic fluid to obtain a liquid-sealed bush.

2. The outer cylinder has an outer cylinder through hole that penetrates the outer cylinder radially, The liquid-sealed bush manufacturing method according to claim 1, wherein in the hydraulic fluid injection step, while the gap is expanded with the hydraulic fluid, the portion of the main body rubber facing the outer cylinder through hole is pushed into the outer cylinder through hole by the hydraulic fluid.

3. The aforementioned through hole in the outer cylinder is A pair of wide holes spaced apart from each other in the circumferential direction, The pair of wide holes are connected to each other, and a narrow hole is provided which has a narrower width in the axial direction than the pair of wide holes. It has, The method for manufacturing a liquid-sealed bush according to claim 2, wherein in the hydraulic fluid injection step, a pair of main liquid chambers are formed between the portion of the main body rubber facing the pair of wide holes and the inner cylinder, and an orifice connecting the pair of main liquid chambers is formed between the portion of the main body rubber facing the narrow hole and the inner cylinder.

4. The liquid-sealed bush manufacturing method according to any one of claims 1 to 3, wherein the outer circumferential surface of the inner cylinder has a bulge-shaped portion that protrudes toward the outer circumferential side.

5. The pair of joint portions of the main body rubber are joined to the outer surface of the inner cylinder, excluding the bulge-shaped portion, and / or to the axial end face of the inner cylinder, over the entire circumference. The liquid-sealed bush manufacturing method according to claim 4, wherein the non-jointed portion of the main body rubber is not joined to the bulge-shaped portion of the inner cylinder.

6. A method for manufacturing a liquid-sealed bush according to claim 2 or 3, further comprising a spacer member fitting step, after the working fluid injection step, of fitting a spacer member into the outer cylinder through hole to thereby seal the outer cylinder through hole.

Images