Rotary damper

Abstract

To enable a resistance of viscous fluid to be adjusted according to an ambient temperature, using a gap that is formed between a peripheral wall of a fluid chamber and a vane and allows the viscous fluid to pass therethrough.SOLUTION: The present invention provides a rotary damper comprising a fluid chamber (40) into which viscous fluid is injected, a vane (22) installed in the fluid chamber, and a resin member (30) installed between a peripheral wall (11) of the fluid chamber and the vane, where the resin member comprises a covering part (31) that covers the tip of the vane and is installed with a gap (50) between itself and the peripheral wall, and an engaging portion (32) that engages with the vane to prevent the covering part from moving toward the peripheral wall, and linear expansion coefficients of the vane and the peripheral wall are smaller than a linear expansion coefficient of the resin member.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to a rotary damper. [Background technology]

[0002] Conventionally, a rotary damper is known that includes a fluid chamber into which a viscous fluid is injected, a vane installed in the fluid chamber, and a seal member installed between the peripheral wall of the fluid chamber and the vane. For example, the following Patent Document 1 discloses a seal member used in such a rotary damper. This seal member includes a covering portion (sliding contact portion 33) that covers the tip of the vane (rotor 21) (see FIG. 3 of Patent Document 1).

[0003] However, in the seal member disclosed in Patent Document 1, the covering portion (sliding portion 33) is always in contact with the peripheral wall of the fluid chamber (the inner wall of the casing 1) in order to obtain a seal between the vane and the peripheral wall (see the examples and FIG. 1 of Patent Document 1). Therefore, in this rotary damper, the resistance of the viscous fluid cannot be adjusted according to the ambient temperature by utilizing the gap formed between the peripheral wall and the vane and through which the viscous fluid can pass. That is, since the viscosity of the viscous fluid changes with the change in the ambient temperature, in this rotary damper, the viscosity of the viscous fluid increases at low temperatures (for example, the ambient temperature is -30 degrees Celsius), but the resistance of the viscous fluid increases because the peripheral wall of the fluid chamber (the inner wall of the casing 1) and the vane are sealed by the covering portion and there is no gap between the peripheral wall and the vane through which the viscous fluid can pass. As a result, the braking force at low temperatures is greater than the braking force at normal temperatures (for example, the ambient temperature is +25 degrees Celsius). On the other hand, at high temperatures (for example, when the ambient temperature is +80 degrees Celsius), the viscosity of the viscous fluid decreases, but the gap between the peripheral wall of the fluid chamber (the inner wall of the casing 1) and the vane is sealed by the covering portion, and there is no gap between the peripheral wall and the vane through which the viscous fluid can pass, so the resistance of the viscous fluid is reduced. As a result, the braking force at high temperatures is smaller than the braking force at normal temperatures. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 3053156 Summary of the Invention [Problem to be solved by the invention]

[0005] The problem that the present invention aims to solve is to make it possible to adjust the resistance of the viscous fluid in accordance with the ambient temperature by utilizing the gap formed between the peripheral wall of the fluid chamber and the vane, through which the viscous fluid can pass. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention provides a rotary damper comprising a fluid chamber into which a viscous fluid is injected, a vane installed in the fluid chamber, and a resin member installed between a peripheral wall of the fluid chamber and the vane, wherein the resin member comprises a covering portion that covers the tip of the vane and is installed with a gap between it and the peripheral wall, and an engaging portion that engages with the vane to prevent the covering portion from moving toward the peripheral wall, and wherein the linear expansion coefficients of the vane and the peripheral wall are smaller than the linear expansion coefficient of the resin member. Effect of the Invention

[0007] According to the present invention, the resin member installed between the peripheral wall of the fluid chamber and the vane includes a covering portion that covers the tip of the vane and is installed with a gap between it and the peripheral wall, and an engaging portion that engages with the vane to prevent the covering portion from moving toward the peripheral wall, and since the linear expansion coefficients of the vane and the peripheral wall are smaller than the linear expansion coefficient of the resin member, the resistance of the viscous fluid can be adjusted according to the ambient temperature by utilizing the gap formed between the peripheral wall and the vane and through which the viscous fluid can pass, and as a result, the braking force can be made uniform regardless of the ambient temperature. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a vertical cross-sectional view of a rotary damper according to an embodiment. [Diagram 2] FIG. 2 is a cross-sectional view of the rotary damper according to the embodiment. [Diagram 3] FIG. 3 is a perspective view of a rotor employed in the embodiment. [Figure 4] FIG. 4 is a plan view of the rotor employed in the embodiment. [Diagram 5] FIG. 5 is a perspective view of a resin member used in the embodiment. [Figure 6] FIG. 6 is a plan view of a resin member used in the embodiment. [Figure 7] FIG. 7 is an enlarged view showing a gap formed between the peripheral wall of the fluid chamber and the vane through which the viscous fluid can pass. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to these embodiments. EXAMPLES

[0010] 1 and 2, the rotary damper according to the embodiment includes a housing 10, a rotor 20, and a resin member 30. The housing 10 and the rotor 20 are made of a metal such as a zinc alloy, and the resin member 30 is made of a resin such as polyoxymethylene. Therefore, the linear expansion coefficients of the vanes 22 constituting the rotor 20 and the peripheral wall 11 constituting the housing 10 are smaller than the linear expansion coefficient of the resin member 30.

[0011] The housing 10 includes a cylindrical peripheral wall 11, a partition wall 12 protruding from the peripheral wall 11, an upper wall 13 closing one end of the peripheral wall 11, and a lower wall 14 closing the other end of the peripheral wall 11. The partition wall 12 is a partition that separates two fluid chambers 40 formed in the housing 10.

[0012] The fluid chamber 40 is a space into which a liquid viscous fluid such as oil is injected, and is formed around the shaft 21 that constitutes the rotor 20. The fluid chamber 40 is divided into two chambers, a first chamber 41 and a second chamber 42, by the vane 22 that constitutes the rotor 20.

[0013] 3, the rotor 20 includes a shaft 21 and vanes 22 protruding from the shaft 21. The shaft 21 is connected to an object that transmits a rotational force to the rotor 20. However, depending on the mode of use, there may be cases where the housing 10 rotates around the rotor 20. In this case, the shaft 21 is connected to an object that prevents the rotor 20 from rotating.

[0014] As shown in FIG. 2, the vane 22 is disposed in the fluid chamber 40 and moves within the fluid chamber 40 as the shaft 21 rotates.

[0015] 4, both side surfaces 22a, 22b of the vane 22 are inclined so that the cross section (longitudinal cross section) of the vane 22 becomes larger toward the tip 22c. In the embodiment, the entire side surfaces 22a, 22b are inclined so that the inclination continues from the base 22d of the vane 22 to the tip 22c of the vane 22, but a slope may be formed on only a part of the side surfaces 22a, 22b (for example, the base 22d of the vane 22 and the part from halfway to the tip 22c of the vane 22 to the tip 22c of the vane 22).

[0016] With reference to FIG. 5, the resin member 30 is configured to have a covering portion 31 and an engaging portion 32.

[0017] The covering portion 31 is a portion that covers the tip surface of the vane 22, and has a shape that can cover the entire tip 22c of the vane 22. As shown in Fig. 7, the covering portion 31 is installed with a gap 50 between it and the peripheral wall 11 of the fluid chamber 40 (the peripheral wall 11 that constitutes the housing 10).

[0018] 6, the engagement portion 32 is composed of a first engagement portion 32a extending downward from the left end of the covering portion 31, and a second engagement portion 32b extending downward from the right end of the covering portion 31. The first engagement portion 32a and the second engagement portion 32b have inclined inner surfaces 32c and 32d that match the inclinations of the side surfaces 22a and 22b of the vane 22, respectively.

[0019] As shown in FIG. 7, the engagement portions 32 are disposed on both sides of the vane 22 such that the vane 22 is sandwiched between the first engagement portion 32a and the second engagement portion 32b.

[0020] 7, the covering portion 31 of the resin member 30 is disposed with a gap 50 between it and the peripheral wall 11 of the fluid chamber 40 (the peripheral wall 11 constituting the housing 10), so that the gap 50 through which the viscous fluid can pass is formed between the vane 22 and the peripheral wall 11 of the fluid chamber 40. This gap 50 is the gap between the covering portion 31 of the resin member 30 and the peripheral wall 11 of the fluid chamber 40.

[0021] In the rotary damper according to the embodiment, when the shaft 21 rotates in one direction (clockwise in FIG. 2), the vane 22 pressurizes the viscous fluid in the first chamber 41. The viscous fluid in the first chamber 41 passes through the gap 50 between the covering portion 31 of the resin member 30 and the peripheral wall 11 of the fluid chamber 40 and moves to the second chamber 42. The gap 50 is set to a dimension that generates resistance to the viscous fluid when the viscous fluid passes through it, and therefore, when the shaft 21 rotates, a braking force that decelerates the rotational speed of the shaft 21 is generated.

[0022] When the shaft 21 rotates in the reverse direction (counterclockwise in FIG. 2), the vane 22 pressurizes the viscous fluid in the second chamber 42. The viscous fluid in the second chamber 42 passes through the gap 50 between the covering portion 31 of the resin member 30 and the peripheral wall 11 of the fluid chamber 40 and moves to the first chamber 41. Therefore, similar to the case where the shaft 21 rotates in one direction, a braking force that decelerates the rotational speed of the shaft 21 is generated when the shaft 21 rotates.

[0023] In the rotary damper according to the embodiment, the linear expansion coefficient of the vane 22 and the peripheral wall 11 of the fluid chamber 40 (the peripheral wall 11 constituting the housing 10) is smaller than that of the resin member 30, so that the vane 22 and the peripheral wall 11 of the fluid chamber 40 hardly shrink even when the ambient temperature becomes low (-30 degrees Celsius), and maintain approximately the same dimensions as at room temperature (+25 degrees Celsius). On the other hand, the linear expansion coefficient of the resin member 30 is larger than that of the vane 22 and the peripheral wall 11 of the fluid chamber 40, so that the resin member 30 shrinks as the ambient temperature decreases from room temperature to a low temperature. As a result, the dimension D (see FIG. 7) of the gap 50 that allows the movement of the viscous fluid between the first chamber 41 and the second chamber 42 expands due to the shrinkage of the resin member 30 when the ambient temperature decreases from room temperature. Therefore, even if the viscosity of the viscous fluid increases due to a decrease in the ambient temperature, the increase in the resistance of the viscous fluid associated with the increase can be suppressed.

[0024] The vane 22 and the peripheral wall 11 of the fluid chamber 40 hardly expand even when the ambient temperature becomes high (+80 degrees Celsius), and maintain approximately the same dimensions as at room temperature. On the other hand, the resin member 30 expands as the ambient temperature rises from room temperature to a high temperature. As a result, the dimension D of the gap 50 that allows the viscous fluid to move between the first chamber 41 and the second chamber 42 shrinks due to the expansion of the resin member 30 when the ambient temperature rises from room temperature. Therefore, even if the viscosity of the viscous fluid decreases due to an increase in the ambient temperature, the accompanying decrease in the resistance of the viscous fluid can be suppressed.

[0025] As described above, the rotary damper of the embodiment can adjust the resistance of the viscous fluid in accordance with the ambient temperature by utilizing the gap 50 formed between the vane 22 and the peripheral wall 11 of the fluid chamber 40 (i.e., the gap between the covered portion 31 of the resin member 30 and the peripheral wall 11 of the fluid chamber 40) through which the viscous fluid can pass, thereby making it possible to uniformize the braking force regardless of the ambient temperature, and more specifically, to reduce the difference between the braking force at low temperatures and the braking force at room temperature, and also to reduce the difference between the braking force at room temperature and the braking force at high temperatures.

[0026] As described above, the rotary damper according to the embodiment prevents the covered portion 31 of the resin member 30 from moving toward the peripheral wall 11 of the fluid chamber 40 (the peripheral wall 11 constituting the housing 10) by the engagement of the engagement portion 32 of the resin member 30 with the vane 22. The shape of the engagement portion 32 for engaging with the vane 22 and the shape of the vane 22 are not limited, but the configuration in which the engagement is achieved by surface contact between the inclined surfaces as in the embodiment is preferable because the shapes of the engagement portion 32 and the vane 22 can be simplified.

[0027] Furthermore, metal has a smaller linear expansion coefficient than resin, which is the material of the resin member 30, and is therefore suitable as a material for the vane 22 and the peripheral wall 11 of the fluid chamber 40 (the peripheral wall 11 that constitutes the housing 10). [Explanation of symbols]

[0028] 10. Housing 11 Peripheral wall (peripheral wall of fluid chamber) 12 Bulkhead 13 Upper wall 14 Lower wall 20 rotors 21 Shaft 22 Vane 30 Resin parts 31 Covering part 32 Engagement part 32a First engaging part 32b Second engaging part 40 Fluid chamber 41 Room 1 42 Room 2 50 Gap

Claims

1. a fluid chamber into which a viscous fluid is injected, a vane disposed in the fluid chamber, and a resin member disposed between a peripheral wall of the fluid chamber and the vane, the resin member includes a covering portion that covers the tip of the vane and is installed with a gap between it and the peripheral wall, and an engaging portion that engages with the vane to prevent the covering portion from moving toward the peripheral wall, The rotary damper, wherein the linear expansion coefficient of the vane and the peripheral wall is smaller than the linear expansion coefficient of the resin member.

2. 2. The rotary damper of claim 1, wherein the vane has sloped sides such that a cross section of the vane expands toward its tip, the engagement portions are disposed on opposite sides of the vane, and each of the engagement portions has a sloped inner surface matching the slope of each side of the vane.

3. 3. The rotary damper according to claim 1, wherein the vane and the peripheral wall are made of metal.

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