Rotary damper

Abstract

Provided is a rotary damper capable of appropriately removing bubbles generated during assembly.　The present invention provides a rotary damper that comprises a housing, a shaft, a cap, and a sealing member, wherein: the housing has a bottomed cylindrical shape having a filling space, and is configured such that the filling space is filled with viscous fluid; the shaft is configured to be fitted into the housing so as to be capable of rotating relative thereto; the cap has a cylindrical shape, has an insertion hole through which the shaft is inserted, and is configured such that an outer peripheral surface thereof comes into contact with an inner peripheral surface of the housing, and an inner peripheral surface thereof comes into contact with the sealing member; the sealing member has an annular shape, and is attached to the shaft such that the inner peripheral surface thereof comes into contact with the shaft; and the filling space is sealed by the cap coming into contact with the sealing member between the inner peripheral surface of the housing and the shaft.

Description

Rotary damper

[0001] The present invention relates to a rotation damper for applying an appropriate rotational resistance to a hinge shaft of an opening / closing member.

[0002] Patent Document 1 discloses a rotation damper for applying an appropriate rotational resistance to a hinge shaft of an opening / closing member such as a lid for a console box of a vehicle.

[0003] Patent No. 4657083

[0004] When assembling a rotational damper, air bubbles sometimes form in the viscous fluid in the filled space of the housing when the shaft is introduced into the filled space in the housing. In such cases, with conventional technology, it is difficult to remove the air bubbles from the viscous fluid in the filled space because the filled space of the housing is sealed when the shaft is installed. Air bubbles in the viscous fluid may prevent the rotational damper from applying a stable braking torque to the hinge shaft. Therefore, a technology that can properly remove air bubbles that form during assembling a rotational damper is desired.

[0005] The present invention has been made in view of the above circumstances, and aims to provide a rotary damper that can properly remove air bubbles that are generated during assembly.

[0006] According to the present invention, the following inventions are provided: [1] A rotary damper comprising a housing, a shaft, a cap, and a seal member, wherein the housing is cylindrical with a bottom and has a filling space configured to be filled with a viscous fluid, the shaft is configured to be attached to the housing so as to be rotatable relative to the housing, and has a flange portion and a seal member attachment portion, the flange portion is formed with an outer diameter that matches the inner diameter of the housing, the seal member attachment portion is configured so that the seal member is attached closer to an opening of the housing than the flange portion, and the cap is cylindrical and has a cap through which the shaft is inserted. a rotary damper having an insertion hole through which the cap is inserted, the outer peripheral surface of which abuts the inner peripheral surface of the housing, and the inner peripheral surface of which abuts the seal member, the seal member being annular and attached to the shaft so that its inner peripheral surface abuts the shaft, the filled space being sealed between the inner peripheral surface of the housing and the shaft by the inner peripheral surface of the cap abutting the seal member, and a space defined by the cap, the seal member attachment portion, the inner peripheral surface of the housing, and the flange portion being configured as a seal chamber for accommodating the seal member. [2] The rotary damper according to [1], wherein a first clearance is formed between the cap and the flange portion in the seal chamber when the filled space is sealed. [3] The rotary damper according to [1] or [2], wherein the housing has an end face on the opening side, and a second clearance is formed between the cap and the end face when the filled space is sealed.[4] The rotary damper according to any one of [1] to [3], wherein the cap has a first surface, a joint portion, an inner circumferential surface, and a guide portion, the first surface faces the flange portion of the shaft, the joint portion is configured to be welded to the housing, the inner circumferential surface has a seal portion and a bearing portion, the seal portion is an area that abuts against the seal member when the filling space is sealed, the bearing portion is an area that supports the shaft so that it can rotate relatively freely, the guide portion is disposed between the first surface and the joint portion, and is configured to have a length that is equal to or longer than the length of the welded area with the housing in the rotational axis direction of the rotary damper. [5] The rotary damper according to any one of [1] to [4], wherein the housing and the shaft have attachment portions that can be attached to a rotating member side and a main body member side, respectively, and the attachment portion of the housing and the attachment portion of the shaft are configured to be symmetrical to each other in the rotational axis direction of the rotary damper.

[0007] In the rotary damper of the present invention, when the shaft with the sealing member attached is attached to the housing, the filling space of the housing is not sealed until the cap is attached, so even if air bubbles remain in the viscous fluid during assembly, they can be easily removed appropriately.

[0008] FIG. 1A is a perspective view of a rotary damper 10 according to one embodiment of the present invention, FIG. 1B is a perspective view showing a state in which a shaft 14 and a cap 16 have been removed from a housing 12, and FIG. 1C is a perspective view of the rotary damper 10 viewed from a different angle than FIG. 1A. FIG. 2A is a cutaway view of the housing 12 and the cap 16 of the rotary damper 10 of FIG. 1A, FIG. 2B is a side cross-sectional view of the rotary damper 10, and FIG. 2C is an enlarged view of region A in FIG. 2B. FIG. 3A is a view of the housing 12 viewed from an angle allowing the interior to be seen, FIG. 3B is a perspective view of the shaft 14, FIG. 3C is a plan view of the rotary damper 10, FIG. 3D is a cross-sectional view taken along line B-B of FIG. 3C, FIG. 3E is a front view of the rotary damper 10, and FIG. 3F is a cross-sectional view taken along line C-C of FIG. 3E. FIG. 4A is a perspective view of the cap 16, and FIG. 4B is a side cross-sectional view of the cap 16. Fig. 5A is a perspective view showing the rotary damper 10 in a state before assembly, and Fig. 5B is a view showing the housing 12 in a state before assembly. Fig. 6A is a view showing the state in which the shaft 14 with the seal member 18 attached is being attached to the housing 12, Fig. 6B is a view showing the rotary damper 10 before the cap 16 is attached, Fig. 6C is a view showing the rotary damper 10 after the cap 16 is attached, and Fig. 6D is an enlarged view of the vicinity of the seal member 18 in Fig. 6C.

[0009] The following describes embodiments of the present invention. The various features shown in the following embodiments can be combined with each other. Furthermore, each feature can be an independent invention.

[0010] <Overall Configuration of Rotary Damper 10> The rotary damper 10 is configured to apply a suitable rotational resistance to a hinge shaft (hinge portion) that connects a rotating member, such as a lid, to a main body member. In this embodiment, the rotary damper 10 is intended for use in generating a braking torque for damping the rotational movement of a lid for a console box in a car or a trash can lid, but is not limited to this. As shown in Figures 1A to 1C, the rotary damper 10 includes a housing 12, a shaft 14, a cap 16, and a sealing member (e.g., an O-ring) 18.

[0011] 2A to 2C and 3A, the housing 12 is made of resin or the like and has a bottomed cylindrical shape (bottomed tubular shape) with a filling space 121. For ease of explanation, FIG. 2A shows the housing 12 and cap 16 cut away. The filling space 121 of the housing 12 is filled with a viscous fluid for generating braking torque. In this embodiment, silicone oil is used as the viscous fluid, but viscous fluids other than silicone oil may also be used.

[0012] The housing 12 also has a bearing portion 122, blade portions 123, an end surface 124, and an attachment portion 125. The bearing portion 122 is configured to support the first shaft portion 14a at the tip of the shaft 14 so as to be relatively rotatable. As shown in Fig. 3A, the blade portions 123 are provided to rise from an inner circumferential surface 128. The end surface 124 is a surface facing a flange portion 163 of the cap 16, which will be described later. The attachment portion 125 is configured to be connected to a hinge shaft of a rotating member (lid) or a main body member.

[0013] <Shaft 14> The shaft 14 is configured to be mounted to the housing 12 so as to be rotatable relative to the housing 12. The shaft 14 is made of resin, metal, or the like. The shaft 14 has a second shaft portion 14b and a third shaft portion 14c arranged so as to be continuous with the first shaft portion 14a at the tip. A blade portion 143 is provided on the second shaft portion 14b. An attachment portion 145 is provided on the third shaft portion 14c. The attachment portion 145 is configured to be connected to a hinge shaft of a rotating member (lid) or a main body member. The attachment portion 145 of the shaft 14 and the attachment portion 125 of the housing 12 are configured to have symmetrical shapes (both convex or concave) in the direction of the rotation axis of the rotary damper 10. Therefore, the attachment portion 145 and the attachment portion 125 can be attached to either the hinge shaft on the rotating member side or the hinge shaft on the main body member side. Furthermore, in order to enable the mounting portion 145 and the mounting portion 125 to rotate integrally with the hinge shaft of the rotating member (lid) or the main body member, each mounting portion has an H-cut portion whose cross section, normal to the rotation axis direction, is processed into an oval shape. However, the shapes of the mounting portion 145 and the mounting portion 125 may be other shapes such as a cylindrical shape, and other flat cuts may be used instead of the H-cut.

[0014] A flange portion 142 and a seal member attachment portion 146 are provided at the boundary between the second shaft portion 14b and the third shaft portion 14c. The flange portion 142 is formed with an outer diameter that matches the inner diameter of the housing 12. The seal member attachment portion 146 is a recess formed around the entire periphery on the opening side (third shaft portion 14c side) of the flange portion 142, and the seal member 18 is attached here.

[0015] <Braking Torque During Relative Rotation Between Housing 12 and Shaft 14> Here, using Figures 3A to 3F, the braking torque due to the blades 123 of the housing 12 and the blades 143 of the shaft 14 will be described. Two blades 123 are provided facing each other at 180-degree opposing positions (positions symmetrical with respect to the rotation axis) on the inner circumferential surface 128. On the other hand, two blades 143 are provided at 180-degree opposing positions on the circumferential surface of the second shaft portion 14b. Also, as shown in Figure 3B, a groove 144 is provided in the first shaft portion 14a of the shaft 14. The groove 144 has the function of guiding a viscous fluid interposed between the bearing portion 122 of the housing 12 and the first shaft portion 14a of the shaft 14 toward the second shaft portion 14b. Furthermore, even if air becomes trapped in the viscous fluid inside the bearing portion 122 of the housing 12 during assembly, the air can be released to the outside of the housing 12 via the groove portion 144, which has the advantageous effect of allowing the air to escape.

[0016] When the shaft 14 rotates relative to the housing 12, the flow of the viscous fluid in the filled space 121 of the housing 12 is restricted by the vanes 123 and 143. During the relative rotation between the housing 12 and the shaft 14, the viscous fluid moves between multiple chambers (four chambers in this embodiment) defined by the vanes 123 and 143 in the filled space 121. The viscous fluid moves through narrow gaps, generating resistance against the relative rotation between the housing 12 and the shaft 14, which becomes a braking torque. A desired amount of braking torque can be obtained by appropriately adjusting the number and arrangement of the vanes 123 and 143, the size of the gap between the vanes 123 and the second shaft portion 14b, and the size of the gap between the vanes 143 and the inner circumferential surface 128, etc.

[0017] <Cap 16> The cap 16 is made of resin and has a cylindrical shape as shown in FIGS. 4A and 4B . The cap 16 has an insertion hole 161 through which the third shaft portion 14c of the shaft 14 is inserted. When attached to the housing 12, the cap 16 is configured so that its outer peripheral surface abuts against the inner peripheral surface 128 of the housing 12, and its inner peripheral surface 162 inside the insertion hole 161 abuts against the seal member 18. More specifically, the inner peripheral surface 162 has a seal portion 162a and a bearing portion 162b. The seal portion 162a is a region that abuts against the seal member 18 when the cap 16 is attached (when the filling space 121 is sealed). The abutment or pressure contact between the seal portion 162a and the seal member 18 seals the filling space 121 of the housing 12. The bearing portion 162b is a region that supports the third shaft portion 14c of the shaft 14 so that it can rotate relatively freely. The cap 16 is configured so that, in the rotation axis direction (left-right direction in FIG. 4B ), the length of the seal portion 162a is greater than the thickness (wire diameter) of the cross section of the seal member 18, and the length of the bearing portion 162b is greater than the length of the seal portion 162a. By configuring the seal portion 162a and the bearing portion 162b continuously on the inner circumferential surface 162, it is possible to form a guide portion 168 that is longer than the welded region.

[0018] The cap 16 has a flange portion 163, a first surface 165a, a second surface 165b, and a joint portion 166. The flange portion 163 is disposed on the outside of the housing 12 when the cap 16 is attached to the housing 12. In this case, the first surface 165a faces the flange portion 142 of the shaft 14, and the second surface 165b faces the end surface 124 of the housing 12. The joint portion 166 is a region that is welded to the joint portion 126 (see FIG. 2C ) of the housing 12. In this embodiment, the joint portion 166 of the cap 16 is pressed against the joint portion 126 of the housing 12, which is inclined at an angle of approximately 45 degrees with respect to the rotation axis direction, while pressing an ultrasonic horn 20 (see FIG. 6C ) against the axially outer end surface of the cap 16 to generate vibration and heat. Of course, the welding method is not limited to this.

[0019] Compared to typical rotary damper caps, the cap 16 according to this embodiment is configured with a longer distance between the joint 166 and the first surface 165a. This is to prevent molten resin from flowing out and reaching the first surface 165a when welding the joint 126 of the housing 12 to the joint 166 of the cap 16. When the molten resin solidifies during the welding process when the cap 16 is attached, it forms what is known as a weld burr. If this weld burr reaches the first clearance 15a (see FIG. 2C ) between the first surface 165a and the flange portion 142, it can adversely affect the rotary damper 10, such as preventing the desired torque from being obtained, individual variations in torque, abnormal noise during operation, reduced durability, and welding at undesired locations. For this reason, the cap 16 is provided with a guide portion 168 that is sufficiently long in the rotational axis direction. In the direction of the rotation axis, the length of the guide portion 168 is preferably at least twice the length of the welded region between the joint portion 126 and the joint portion 166, and more preferably at least three times the length.

[0020] <Sealing Member 18> The sealing member 18 has an annular shape and is attached to the sealing member attachment portion 146 of the shaft 14 so that its inner circumferential surface abuts against it, as shown in FIG. 2B . The sealing member attachment portion 146 is disposed outside the flange portion 142 of the shaft 14. Therefore, when the cap 16 is attached, the sealing member 18 attached to the sealing member attachment portion 146 can abut against the seal portion 162a on the inner circumferential surface 162 of the cap 16. Unlike conventional sealing, which is achieved by a seal between the inner circumferential surface 128 of the housing 12 and the sealing member 18, when the cap 16 is attached, the sealing member 18 and the seal portion 162a seal the filling space 121. More precisely, the sealing is achieved by sandwiching the cap 16 and the sealing member 18 between the sealing member attachment portion 146 and the inner circumferential surface 128. In other words, the space defined by the cap 16, the seal member attachment portion 146, the inner circumferential surface 128, and the flange portion 142 is configured as a seal chamber that accommodates the seal member 18. In this embodiment, a rubber O-ring is used as the seal member 18, but the present invention is not limited to this.

[0021] The rotary damper 10 is configured so that a second clearance 15b is formed in addition to the first clearance 15a when the cap 16 is attached. The second clearance 15b is provided between the second surface 165b of the flange portion 163 of the cap 16 and the end surface 124 of the housing 12 on the opening side. The second clearance 15b facilitates assembly so that the first clearance 15a is set to a desired size. The second clearance 15b also serves to maintain the first clearance 15a at a desired size even if a dimensional error or the like occurs in the cap 16. To properly form the second clearance 15b, for example, it is recommended to design the distance between the flange portion 163 and the joint portion 166 of the cap 16 to be slightly longer than usual.

[0022] By providing the first clearance 15a and the second clearance 15b, the degree of freedom in adjusting the braking torque setting is improved.

[0023] <Assembly of the Rotary Damper 10> Next, assembly of the rotary damper 10 will be described using Figures 5 and 6. Figure 5A shows the housing 12, shaft 14, cap 16, and seal member 18 before assembly of the rotary damper 10. First, as shown in Figure 5B, the housing 12 is placed with the attachment portion 125 facing downward, and a predetermined amount of viscous fluid (not shown) is injected into the filling space 121. Thereafter, as shown in Figure 6A, the seal member 18 is attached to the seal member attachment portion 146 of the shaft 14, and the shaft 14 is introduced into the filling space 121.

[0024] It is conceivable that air may be mixed into the viscous fluid when the shaft 14 is introduced into the filled space 121. The rotary damper 10 employs a configuration in which, even when the shaft 14 with the sealing member 18 is attached to the housing 12, the filled space 121 is not completely sealed until the cap 16 is attached. In other words, the sealing function of the sealing member 18 is not fully realized at this point. For this reason, it is recommended that a predetermined degassing time be allowed to pass after the shaft 14 is attached to the housing 12 before attaching the cap 16. This degassing time can be appropriately set depending on the viscosity of the viscous fluid. For example, when a viscous fluid with a low viscosity is used, the degassing time is shortened. On the other hand, when a viscous fluid with a high viscosity is used, the degassing time is lengthened. In this way, by setting an appropriate degassing time depending on the viscosity of the viscous fluid used, air bubbles mixed in the viscous fluid are less likely to remain.

[0025] After a predetermined degassing time has elapsed, as shown in FIG. 6C , the cap 16 is attached to the housing 12, and ultrasonic welding is performed using an ultrasonic horn 20 with a ring-shaped tip. The joint 126 of the housing 12 and the joint 166 of the cap 16 are melted by frictional heat generated at their interface by ultrasonic vibrations, and are integrated at the welded portion 22 (see FIG. 6D ). The molten resin flowing out of the welded portion 22 is typically contained in a burr pocket 24. The cap 16 is provided with a sufficiently long guide portion 168, so the molten resin does not reach the first clearance 15 a. Furthermore, because the cap 16 is designed to form the second clearance 15 b, there is no inconvenience such as being unable to set the first clearance 15 a to a desired size due to physical interference between the housing 12 and the cap 16, etc.

[0026] As described above, in the rotational damper 10 according to this embodiment, it is easy to remove air bubbles from the viscous fluid in the filling space 121 of the housing 12. Also, it is easy to obtain a desired braking torque by suitably adjusting the size of the first clearance 15a. Furthermore, the inconvenience of loss of stability in the operation of the rotational damper 10 due to welding burrs generated during ultrasonic welding is unlikely to occur.

[0027] <Other Embodiments> In the above-described embodiment, a configuration is adopted in which a braking torque is generated regardless of the direction of rotation, but it is also possible to adopt a configuration in which a braking torque is generated only during rotation in one direction using movable vanes, etc. Furthermore, although a cylindrical shape is adopted as the shape of the rotary damper 10, the outer shape of the rotary damper 10 does not necessarily have to be circular, and other shapes can be adopted.

[0028] 10: Rotary damper, 12: Housing, 14: Shaft, 14a: First shaft portion, 14b: Second shaft portion, 14c: Third shaft portion, 15a: First clearance, 15b: Second clearance, 16: Cap, 18: Sealing member, 20: Ultrasonic horn, 22: Welded portion, 24: Burr pocket, 121: Filling space, 122: Bearing portion, 123: Blade portion, 124: End surface, 125: mounting portion, 126: joint portion, 128: inner peripheral surface, 142: flange portion, 143: blade portion, 144: groove portion, 145: mounting portion, 146: seal member mounting portion, 161: insertion hole, 162: inner peripheral surface, 162a: seal portion, 162b: bearing portion, 163: flange portion, 165a: first surface, 165b: second surface, 166: joint portion, 168: guide portion

Claims

1. A rotary damper comprising a housing, a shaft, a cap, and a seal member, wherein the housing is cylindrical with a bottom and has a filling space, and is configured so that a viscous fluid is filled in the filling space, the shaft is configured to be attached to the housing so as to be able to rotate relatively thereto, and has a flange portion and a seal member attachment portion, the flange portion is formed with an outer diameter that matches the inner diameter of the housing, and the seal member attachment portion is configured so that the seal member is attached closer to the opening of the housing than the flange portion, the cap is cylindrical and has an insertion hole through which the shaft is inserted, and its outer surface abuts against the inner surface of the housing and its inner surface abuts against the seal member, the seal member is annular and is attached to the shaft so that its inner surface abuts against the shaft, and the filling space is sealed between the inner surface of the housing and the shaft by the inner surface of the cap abutting against the seal member, A rotary damper, wherein a space defined by the cap, the seal member attachment portion, the inner circumferential surface of the housing, and the flange portion is configured as a seal chamber that accommodates the seal member.

2. A rotary damper according to claim 1, wherein a first clearance is formed between the cap and the flange portion in the seal chamber when the filling space is sealed.

3. A rotary damper according to claim 2, wherein the housing has an end face on the opening side, and when the filling space is sealed, a second clearance is formed between the cap and the end face.

4. A rotary damper as set forth in claim 2 or claim 3, wherein the cap has a first surface, a joint, an inner circumferential surface, and a guide portion, the first surface faces the flange portion of the shaft, the joint portion is configured to be welded to the housing, the inner circumferential surface has a seal portion and a bearing portion, the seal portion is an area that abuts against the seal member when the filling space is sealed, and the bearing portion is an area that supports the shaft so that it can rotate relatively freely, and the guide portion is arranged between the first surface and the joint portion, and is configured to have a length in the direction of the rotational axis of the rotary damper that is equal to or greater than the length of the welded area with the housing.

5. A rotary damper as set forth in claim 2 or 3, wherein the housing and the shaft have mounting portions that can be attached to the rotating member side and the main body member side, respectively, and the mounting portion of the housing and the mounting portion of the shaft are configured to have shapes that are symmetrical to each other in the direction of the rotation axis of the rotary damper.

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