Vibration Damping Device

Abstract

To absorb vibration energy of a seat in two directions.SOLUTION: A vibration damping device 40 includes: a shoulder bolt 42 attached to a seat frame 10A; a weight member 46 in which a through hole 46A into which the shoulder bolt 42 is inserted is eccentrically provided and which may move in an axial direction D of the shoulder bolt 42 and in a circumferential direction E of the shoulder bolt 42; and coil springs 50 which are disposed at both sides of the weight member 46 in the axial direction D and allow the weight member 46 to vibrate in the axial direction D and the circumferential direction E.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a vibration damping device. [Background technology]

[0002] 2. Description of the Related Art It is known to provide a vibration damping device for damping vibrations of a seat in a vehicle or the like (see, for example, Patent Document 1).

[0003] Patent Document 1 discloses a technology in which a dynamic damper including a weight and an elastic member that supports the weight so that it can vibrate is provided with a movement restriction means that restricts the movement of the weight in a predetermined direction. This makes it possible to restrict the movement of the weight in the predetermined direction in the dynamic damper, thereby efficiently exerting a vibration-damping effect against vibrations in a specific direction that should be damped. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-111295 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, the technique described in Patent Document 1 has a problem in that the weight is configured to vibrate in one direction, and therefore cannot absorb the vibration energy of the seat in two directions.

[0006] SUMMARY OF THE PRESENT EMBODIMENT In consideration of the above, an object of the present invention is to provide a vibration damping device capable of absorbing vibration energy of a seat in two directions. [Means for solving the problem]

[0007] The vibration damping device of the present invention as described in claim 1 comprises an axis member attached to a seat frame, a weight member having an eccentrically arranged through hole through which the axis member is inserted and capable of moving in the axial direction and circumferential direction of the axis member, and spring members arranged on both sides of the weight member in the axial direction and capable of vibrating the weight member in the axial and circumferential directions.

[0008] According to the present invention as set forth in claim 1, by providing a spring member that allows the weight member to vibrate in the axial and circumferential directions, when the seat vibrates, the weight member vibrates in the axial and circumferential directions of the shaft member. Then, by setting the natural frequency of the weight member to correspond to the resonance frequency of the seat, the weight member resonates with the resonance of the seat. As a result, the vibration energy of the seat in the axial direction of the shaft member and the orthogonal direction perpendicular to the axial direction is converted into vibration energy in the axial and circumferential directions of the weight member. As a result, the vibration energy of the seat in the axial direction of the shaft member and the orthogonal direction perpendicular to the axial direction is absorbed, and the vibration of the seat is effectively damped.

[0009] In the vibration damping device of the present invention as described in claim 2, in the vibration damping device as described in claim 1, the spring members arranged on both sides of the weight member in the axial direction are arranged to urge the weight member in opposite directions to each other in the axial direction and to urge the weight member in opposite directions to each other in the circumferential direction.

[0010] According to the present invention as set forth in claim 2, the spring members are provided so as to bias the weight member in opposite directions in the axial direction, so that a spring force acts on the weight member in the axial direction without fixing the weight member and the spring member. Also, the spring members are provided so as to bias the weight member in opposite directions in the circumferential direction, so that a spring force acts on the weight member in the circumferential direction without fixing the weight member and the spring member. Therefore, the spring forces can be constantly applied to the weight member in the axial and circumferential directions. As a result, the vibration of the weight member in the axial and circumferential directions can be stabilized.

[0011] In the vibration damping device of the present invention described in claim 3, in the vibration damping device described in claim 1 or claim 2, the spring member is a torsion coil spring having a spiral compression coil portion and arm portions extending from both ends of the compression coil portion.

[0012] According to the present invention described in claim 3, by making the spring member a torsion coil spring having a spiral compression coil portion and arm portions extending from both ends of the compression coil portion, the compression coil portion acts to vibrate the weight member in the axial direction of the shaft member, and the compression coil portion and the arm portions act to vibrate the weight member in the circumferential direction of the shaft member. Therefore, with a simple configuration, the weight member can be vibrated in the axial direction of the shaft member and the weight member can be vibrated in the circumferential direction of the shaft member. As a result, with a simple configuration, it is possible to absorb the vibration energy of the seat in the axial direction of the shaft member and in the orthogonal direction perpendicular to the axial direction.

[0013] In the vibration damping device of the present invention described in claim 4, in the vibration damping device described in claim 3, the torsion coil spring is arranged in a state compressed in the axial direction and biased in the circumferential direction.

[0014] According to the present invention described in claim 4, by arranging the torsion coil spring in an axially compressed state, when the weight member moves in one axial direction of the shaft member, one of the torsion coil springs is further compressed, and the other torsion coil spring is expanded but maintained in a compressed state. Therefore, when the weight member vibrates in the axial direction, the torsion coil spring is always in contact with the weight member. Furthermore, by arranging the torsion coil spring in a circumferentially biased state, when the weight member moves in one axial direction of the shaft member, one of the torsion coil springs is further biased, and the other torsion coil spring maintains a biased state while the biasing force weakens. Therefore, when the weight member vibrates in the circumferential direction, the torsion coil spring is always in contact with the weight member. As a result, it is possible to suppress abnormal noise generated between the weight member and the torsion coil spring.

[0015] In the vibration damping device of the present invention described in claim 5, in the vibration damping device described in any one of claims 1 to 4, the spring member arranged on one side of the weight member in the axial direction and the spring member arranged on the other side of the weight member in the axial direction are formed to be the same shape.

[0016] According to the present invention as set forth in claim 5, the spring member arranged on one side of the weight member in the axial direction and the spring member arranged on the other side are made to have the same shape, so that the same spring member can be used, thereby reducing the manufacturing cost of the spring member. Effect of the Invention

[0017] The vibration damping device according to the present invention is capable of absorbing the vibration energy of the seat in two directions. [Brief description of the drawings]

[0018] [Figure 1] 1 is a perspective view of a vehicle seat according to an embodiment of the present invention, viewed from diagonally forward left of the seat. [Diagram 2] 1 is a perspective view of a seat frame of a vehicle seat according to an embodiment of the present invention, as viewed from diagonally forward left of the seat. [Diagram 3] 1 is a perspective view showing a state in which a vibration damping device according to an embodiment of the present invention is attached to a bracket attached to a seat frame. [Figure 4] 1 is an exploded perspective view showing a vibration damping device according to an embodiment of the present invention; [Diagram 5] 1 is a side view showing a vibration damping device according to an embodiment of the present invention as viewed from the front of a seat. [Figure 6] 4 is a cross-sectional view showing the vibration damping device according to the present embodiment, showing the AA cross section of FIG. [Figure 7] 2 is a schematic diagram showing a vibration model of the vibration damping device according to the embodiment; FIG. [Figure 8] 8A and 8B are cross-sectional views for explaining the operation of the vibration damping device according to the present embodiment, in which FIG. 8(A) shows a state in which the weight member has been moved to one end side, and FIG. 8(B) shows a state in which the weight member has been moved to the other end side. [Figure 9] 9A and 9B are side views for explaining the operation of the vibration damping device according to the present embodiment, in which FIG. 9A shows a state in which the weight member has moved to the rear side, and FIG. 9B shows a state in which the weight member has moved to the front side. [Figure 10] 13 is a perspective view showing a state in which a vibration damping device according to another embodiment is attached to a bracket attached to a seat frame. FIG. [Figure 11] 13 is a perspective view showing a state in which a vibration damping device according to another embodiment is attached to a bracket attached to a seat frame. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] The vibration damping device according to this embodiment will be described below with reference to the drawings. Note that the arrow FR shown in each drawing indicates the front in the seat front-rear direction, the arrow UP indicates the upper side in the seat up-down direction, and the arrow RH indicates the right side in the seat width direction. Also, the arrow D indicates the axial direction of the stepped bolt, and the arrow E indicates the circumferential direction of the stepped bolt. Hereinafter, when the directions of the front-rear, up-down, and left-right are simply used for the description, they refer to the front-rear, up-down, and left-right directions of the vehicle seat, respectively, and the left-right directions of the vehicle seat, respectively, when facing the traveling direction, unless otherwise specified. Also, when the directions of the one end side and the other end side are simply used for the description, they refer to the axial direction of the stepped bolt, unless otherwise specified. Also, in FIG. 2, the headrest stay of the headrest constituting the seat frame is omitted from the illustration.

[0020] An example of the vibration damping device of this embodiment that is applied to a vehicle seat provided in a vehicle will be described.

[0021] [Vehicle seat configuration] 1 and 2, the vehicle seat 10 includes a seat cushion 12 on which an occupant sits, a seat back 14 that supports the upper body of the occupant, a headrest 16 that is provided on the seat upper side of the seat back 14 and supports the head of the occupant, and a seat frame 10A that forms the framework of the vehicle seat 10. The seat frame 10A includes a cushion frame 18 and a seat back frame 28.

[0022] The seat cushion 12 is formed of a foam such as a urethane pad, and is fixed to a cushion frame 18 shown in FIG.

[0023] 2, slide rails 20 extending along the front-rear direction of the seat are provided on the lower sides of both ends in the seat width direction of the cushion frame 18. The pair of left and right slide rails 20 are fixed to a vehicle body floor portion 26 via front seat brackets 22 provided at the front of the slide rails 20 and rear seat brackets 24 provided at the rear of the slide rails 20. The vehicle seat 10 is slidable along the front-rear direction of the vehicle via the pair of left and right slide rails 20.

[0024] As shown in FIG. 1, the seat back 14, like the seat cushion 12, is formed of a foam such as a urethane pad, and is fixed to a seat back frame 28 shown in FIG.

[0025] 2, the seatback frame 28 includes a lower frame 25 disposed below the seatback frame 28, and an upper frame 27 disposed above the seatback frame 28. The lower frame 25 is provided with a reclining device 29 that enables the seatback frame 28 to be tilted in the front-rear direction of the vehicle relative to the cushion frame 18. A headrest stay (not shown) of the headrest 16 is connected to the upper frame 27. The lower frame 25 and the upper frame 27 are connected via a plurality of bolts 32.

[0026] 2, a vibration damping device 40 is attached to a metal bracket 34 that is attached by a mounting bracket or the like (not shown) to an upper end member 27A that forms the upper end of the upper frame 27. The vibration damping device 40 is provided approximately in the center in the seat width direction.

[0027] 3, the bracket 34 is formed in an L-shape and has a first piece 34A extending in the seat width direction and a second piece 34B extending in the seat front-rear direction. A cylindrical protrusion 34C protruding toward the other end is formed on the side surface of the other end of the second piece 34B.

[0028] [Configuration of vibration damping device] As shown in FIG. 4, the vibration damping device 40 includes a shoulder bolt 42 as a shaft member, a collar member 44, a weight member 46, and a torsion coil spring 50 as a spring member.

[0029] (Shoulder bolt 42) As shown in Figures 4 and 6, the stepped bolt 42 is made of metal and has a shaft portion 42A, a male threaded portion 42C formed on one end side of the shaft portion 42A, a head portion 42B formed on the other end side of the shaft portion 42A, a convex portion 42D formed on the head portion 42B, and a positioning portion 42E formed on the other end side of the male threaded portion 42C.

[0030] The shaft portion 42A is formed in a cylindrical shape. The male screw portion 42C is cylindrical and has a smaller outer diameter than the shaft portion 42A, and has a screw thread formed on its outer circumferential surface.

[0031] Head 42B is formed in an egg shape having an outer diameter larger than shaft 42A. Head 42B is disposed in a position in which the apex of the egg shape faces diagonally upward and forward on the seat. Convex portion 42D is formed in a cylindrical shape protruding toward one end from a surface on one end side of head 42B. Convex portion 42D is formed at a position away from shaft 42A. Convex portion 42D is formed near the apex of egg-shaped head 42B. Convex portion 42D is formed diagonally upward and forward on the seat from shaft 42A.

[0032] The positioning portion 42E is formed between the shaft portion 42A and the male screw portion 42C. The positioning portion 42E is formed in a quadrangular prism shape. Note that the positioning portion 42E may be formed in a polygonal prism shape.

[0033] (Colored material 44) The collar member 44 is disposed radially outward of the shaft portion 42A of the stepped bolt 42. The collar member 44 is made of resin and formed into a cylindrical shape. The inner diameter of the collar member 44 is formed to be approximately the same as the outer diameter of the shaft portion 42A. The shaft portion 42A of the stepped bolt 42 is inserted into the collar member 44, and the outer circumferential surface of the shaft portion 42A is covered by the collar member 44. In other words, the collar member 44 is interposed between the weight member 46 and the shaft portion 42A. In addition, the collar member 44 is interposed between the shaft portion 42A and the coil spring 50.

[0034] (weight member 46) 4 and 6, the weight member 46 is disposed radially outward of the collar member 44. The weight member 46 is made of metal and formed into a rectangular prism shape extending in the axial direction D. The weight member 46 has a through hole 46A penetrating in the axial direction D. The through hole 46A is formed at a position eccentric to the center of gravity of the weight member 46 when viewed from the axial direction D.

[0035] The stepped bolt 42 and the collar member 44 are inserted into the through hole 46A. The weight member 46 is provided so as to be movable in the axial direction D of the stepped bolt 42 via the collar member 44 and to be rotatable in the circumferential direction E of the stepped bolt 42. In other words, the weight member 46 is provided so as to be movable in the axial direction D and the circumferential direction E via the collar member 44, with the stepped bolt 42 as an axis.

[0036] The weight member 46 has a protrusion 46B provided on an end face on the other end side, and a protrusion 46C provided on an end face on one end side.

[0037] The protrusion 46B is formed in a cylindrical shape protruding from the end face on the other end side toward the other end side. The protrusion 46B is formed diagonally downward and forward on the seat from the through hole 46A. The protrusion 46B is formed below the seat from the protrusion 42D.

[0038] The protrusion 46C is formed in a cylindrical shape protruding from an end face on one end side toward one end side. The protrusion 46C is formed diagonally upward and forward from the through hole 46A on the seat.

[0039] (Torsion coil spring 50) 4 and 6, the torsion coil spring 50 is disposed radially outward of the collar member 44. The torsion coil spring 50 is composed of a first torsion coil spring 52 provided on the other end side of the weight member 46 in the axial direction D, and a second torsion coil spring 54 provided on one end side of the weight member 46 in the axial direction D.

[0040] As shown in FIGS. 4 and 5, the first torsion coil spring 52 has a spiral compression coil portion 52A and arm portions 52B extending from both ends of the compression coil portion 52A.

[0041] The compression coil portion 52A is formed in a spiral shape so as to create gaps between the wires and prevent them from being in close contact. The compression coil portion 52A is disposed so as to surround the outer periphery of the collar member 44. The compression coil portion 52A is formed in a size that allows the shaft portion 42A of the shoulder bolt 42 and the collar member 44 to be inserted therethrough. The outer diameter of the compression coil portion 52A is formed larger than the inner diameter of the through hole 46A of the weight member 46.

[0042] The arm portion 52B on one end side is formed to extend downward from one end side of the compression coil portion 52A, and the arm portion 52B on the other end side is formed to extend upward from the other end side of the compression coil portion 52A.

[0043] The first torsion coil spring 52 is disposed between the other end face of the weight member 46 and one end face of the head 42B in a state compressed in the axial direction D. When the first torsion coil spring 52 is biased in the circumferential direction E, the arm portion 52B on the other end side is hooked on the protrusion 42D, and the arm portion 52B on the one end side is hooked on the protrusion 46B.

[0044] The second torsion coil spring 54 has a spiral compression coil portion 54A and arm portions 54B extending from both ends of the compression coil portion 54A, and is formed in the same shape as the first torsion coil spring 52.

[0045] 5, second torsion coil spring 54 is disposed between an end face on one end side of weight member 46 and a side face on the other end side of second piece 34B in a state compressed in axial direction D. When second torsion coil spring 54 is biased in circumferential direction E, arm portion 54B on the other end side is hooked on protrusion 46C, and arm portion 54B on one end side is hooked on protrusion 34C.

[0046] The weight member 46 is biased toward one end by the first torsion coil spring 52, and toward the other end by the second torsion coil spring 54. Elastic energy (biasing force) is stored in the first torsion coil spring 52 and the second torsion coil spring 54. As a result, the weight member 46 is disposed at approximately the center of the shaft portion 42A of the stepped bolt 42 in the axial direction D.

[0047] The weight member 46 is biased in one direction in the circumferential direction E by the first torsion coil spring 52, and is biased in the other direction in the circumferential direction E by the second torsion coil spring 54. Elastic energy (biasing force) is stored in the first torsion coil spring 52 and the second torsion coil spring 54. As a result, the biasing forces of the first torsion coil spring 52 and the second torsion coil spring 54 act on the weight member 46 in the axial direction D and the circumferential direction E, resulting in so-called forced vibration.

[0048] The first torsion coil spring 52 and the second torsion coil spring 54 thus arranged urge the weight member 46 in opposite directions to each other in the axial direction D, and also urge the weight member 46 in opposite directions to each other in the circumferential direction E. The first torsion coil spring 52 and the second torsion coil spring 54 enable the weight member 46 to vibrate in the axial direction D and the circumferential direction E.

[0049] The vibration damping device 40 configured in this manner is attached to the second piece 34B of the bracket 34, as shown in Figures 3 and 6. A rectangular through-hole 34D penetrating the second piece 34B in the plate thickness direction is formed in the second piece 34B. The vibration damping device 40 is positioned with respect to the bracket 34 by inserting the positioning portion 42E of the stepped bolt 42 into the through-hole 34D.

[0050] The vibration damping device 40 is attached to the bracket 34 by attaching a washer 62 and a nut 64 to the male threaded portion 42C of the stepped bolt 42 via the second piece 34B. The vibration damping device 40 is attached to the bracket 34 so that the axial direction D of the stepped bolt 42 is aligned along the seat width direction. The vibration damping device 40 is attached via the bracket 34 to an upper end member 27A arranged on the upper end side of the seat frame 10A.

[0051] The vibration damping device 40 may also be provided on a headrest stay (not shown) of the headrest 16 that supports the head of a seated occupant.

[0052] [Natural frequency of weight member] The natural frequency of the weight member 46 in the axial direction D is set to be the same as the resonant frequency of the vehicle seat 10 in the seat width direction, and the natural frequency of the weight member 46 in the circumferential direction E is set to be the same as the resonant frequency of the vehicle seat 10 in the seat fore-aft direction.

[0053] As shown in FIG. 7, the spring constant k1 of the first torsion coil spring 52 and the spring constant k2 of the second torsion coil spring 54 are set so that the resonant frequency in the seat width direction of the vehicle seat 10 is the same as the natural frequency of the weight member 46 in the axial direction D. For example, in free vibration, if the mass of the weight member 46 is M and the spring constant is k, the frequency (natural frequency) f of the weight member 46 is calculated by Equation (1). In this embodiment, since the vibration is forced, the natural frequency f of the weight member 46 is calculated by Equation (2). In other words, the spring constant k1 of the first torsion coil spring 52 and the spring constant k2 of the second torsion coil spring 54 are set so that the natural frequency f of the weight member 46 in the axial direction D is set to the resonant frequency in the seat width direction of the vehicle seat 10.

[0054] In addition, the spring constant k1 of the first torsion coil spring 52 and the spring constant k2 of the second torsion coil spring 54 are set so that the resonant frequency in the seat front-rear direction of the vehicle seat 10 is the same as the natural frequency in the circumferential direction E of the weight member 46. In other words, the spring constant k1 of the first torsion coil spring 52 and the spring constant k2 of the second torsion coil spring 54 are set so that the natural frequency f of the weight member 46 in the circumferential direction E is set to the resonant frequency in the seat front-rear direction of the vehicle seat 10.

[0055] [Operation of vibration damping device] When vibrations occur in the vehicle during idling or driving, the vehicle seat 10 vibrates via the vehicle body floor portion 26. When the vehicle seat 10 vibrates in the seat width direction at a resonant frequency, as shown in FIG. 8(A), the weight member 46 moves along the collar member 44 to one end side in the axial direction D. At this time, the second torsion coil spring 54 is compressed, and the first torsion coil spring 52 is expanded but maintained in a compressed state. Next, as shown in FIG. 8(B), the weight member 46 moves along the collar member 44 to the other end side in the axial direction D. At this time, the first torsion coil spring 52 is compressed, and the second torsion coil spring 54 is expanded but maintained in a compressed state.

[0056] In this way, the weight member 46 reciprocates in the axial direction D along the collar member 44 due to the first torsion coil spring 52 and the second torsion coil spring 54, and resonates. That is, vibration energy due to vibration at the resonant frequency in the seat width direction of the vehicle seat 10 is converted into kinetic energy that moves the weight member 46. As a result, the vibration energy due to vibration at the resonant frequency in the seat width direction of the vehicle seat 10 is absorbed, and the vibration in the seat width direction of the vehicle seat 10 is damped.

[0057] When the vehicle seat 10 vibrates in the seat fore-and-aft direction at the resonant frequency, as shown in Fig. 9(A), the weight member 46 rotates toward the rear of the seat around the shaft portion 42A of the shoulder bolt 42 via the collar member 44. At this time, the biasing force of the first torsion coil spring 52 increases, and the biasing force of the second torsion coil spring 54 decreases but the biased state is maintained.

[0058] 9(B), the weight member 46 rotates toward the front of the seat around the shaft portion 42A of the shoulder bolt 42 via the collar member 44. At this time, the biasing force of the second torsion coil spring 54 increases, and the biasing force of the first torsion coil spring 52 decreases but the biased state is maintained.

[0059] In this way, the weight member 46 resonates in a pendulum motion in the circumferential direction E by the first torsion coil spring 52 and the second torsion coil spring 54. That is, vibration energy due to vibration of the resonant frequency in the seat front-rear direction of the vehicle seat 10 is converted into kinetic energy that moves the weight member 46. As a result, the vibration energy due to vibration of the resonant frequency in the seat front-rear direction of the vehicle seat 10 is absorbed, and the vibration of the vehicle seat 10 in the seat front-rear direction is damped.

[0060] [Actions and Effects of the Present Embodiment] Next, the operation and effects of the vibration damping device 40 of this embodiment will be described.

[0061] The vibration damping device 40 of this embodiment includes a stepped bolt 42 attached to the seat frame 10A so as to extend in the seat width direction, a weight member 46 having an eccentrically arranged through hole 46A through which the stepped bolt 42 is inserted and which is movable in the axial direction D of the stepped bolt 42 and in the circumferential direction E of the stepped bolt 42, and torsion coil springs 50 arranged on both sides of the axial direction D of the weight member 46 and which enable the weight member 46 to vibrate in the axial direction D and the circumferential direction E.

[0062] By providing the torsion coil spring 50 that allows the weight member 46 to vibrate in the axial direction D, when the vehicle seat 10 vibrates in the seat width direction, the weight member 46 vibrates in the axial direction D of the stepped bolt 42. Then, by setting the natural frequency of the weight member 46 to correspond to the resonance frequency of the vehicle seat 10, the weight member 46 resonates with the resonance of the vehicle seat 10. As a result, the vibration energy of the vehicle seat 10 in the seat width direction is converted into vibration energy in the axial direction D of the weight member 46. As a result, the vibration energy of the vehicle seat 10 in the seat width direction is absorbed, and the vibration of the vehicle seat 10 is effectively damped.

[0063] Moreover, by allowing the weight member 46 to vibrate in the circumferential direction E by the torsion coil spring 50, when the vehicle seat 10 vibrates in the seat front-rear direction, the weight member 46 vibrates in the circumferential direction E of the stepped bolt 42. By setting the natural frequency of the weight member 46 to correspond to the resonance frequency of the vehicle seat 10, the weight member 46 resonates with the resonance of the vehicle seat 10. As a result, the vibration energy of the vehicle seat 10 in the seat front-rear direction is converted into vibration energy in the circumferential direction E of the weight member 46. As a result, the vibration energy of the vehicle seat 10 in the seat front-rear direction is absorbed, and the vibration of the vehicle seat 10 is effectively damped.

[0064] That is, it is possible to absorb vibration energy of the vehicle seat 10 in two directions, that is, the seat width direction and the seat front-rear direction.

[0065] Furthermore, by providing the through hole 46A, through which the stepped bolt 42 is inserted, eccentrically in the weight member 46, when the vehicle seat 10 vibrates, a pendulum vibration is generated in the weight member 46 with the stepped bolt 42 as a fulcrum. Therefore, the vibration of the vehicle seat 10 is easily converted into a pendulum vibration of the weight member 46. As a result, the vibration energy of the vehicle seat 10 in the front-rear direction of the seat is sufficiently absorbed, and the vibration of the vehicle seat 10 is effectively damped.

[0066] In the vibration damping device 40 of this embodiment, the first torsion coil spring 52 and the second torsion coil spring 54, which are arranged on either side of the weight member 46 in the axial direction D, are arranged to urge the weight member 46 in opposite directions to each other in the axial direction D and to urge the weight member 46 in opposite directions to each other in the circumferential direction E.

[0067] The first torsion coil spring 52 and the second torsion coil spring 54 are arranged to bias the weight member 46 in opposite directions in the axial direction D, so that a spring force acts on the weight member 46 in the axial direction D without fixing the weight member 46 to the first torsion coil spring 52 and the second torsion coil spring 54. Also, the first torsion coil spring 52 and the second torsion coil spring 54 are arranged to bias the weight member 46 in opposite directions in the circumferential direction E, so that a spring force acts on the weight member 46 in the circumferential direction E, so that the weight member 46 is not fixed to the first torsion coil spring 52 and the second torsion coil spring 54.

[0068] Therefore, a spring force can be constantly applied to the weight member 46 in the axial direction D and the circumferential direction E. As a result, the spring constant k1 of the first torsion coil spring 52 and the spring constant k2 of the second torsion coil spring 54 can be stabilized, and the vibration of the weight member 46 in the axial direction D and the circumferential direction E can be stabilized. Furthermore, by stabilizing the vibration of the weight member 46 in the axial direction D and the circumferential direction E, the generation of abnormal noise can be suppressed.

[0069] In the vibration damping device 40 of this embodiment, the first torsion coil spring 52 and the second torsion coil spring 54 have helical compression coil portions 52A, 54A and arm portions 52B, 54B extending from both ends of the compression coil portions 52A, 54A.

[0070] The first torsion coil spring 52 and the second torsion coil spring 54 have helical compression coil portions 52A, 54A and arm portions 52B, 54B extending from both ends of the compression coil portions 52A, 54A, so that the compression coil portions 52A, 54A act to cause the weight member 46 to vibrate in the axial direction D of the stepped bolt 42, and the compression coil portions 52A, 54A and the arm portions 52B, 54B act to cause the weight member 46 to vibrate in the circumferential direction E of the stepped bolt 42. Therefore, with a simple configuration, the weight member 46 can be vibrated in the axial direction D of the stepped bolt 42 and the weight member 46 can be vibrated in the circumferential direction E of the stepped bolt 42. As a result, with a simple configuration, it is possible to absorb vibration energy of the vehicle seat 10 in the seat width direction and the seat front-rear direction.

[0071] In the vibration damping device 40 of this embodiment, the first torsion coil spring 52 and the second torsion coil spring 54 are provided in a state where they are compressed in the axial direction D and biased in the circumferential direction E.

[0072] By disposing the first torsion coil spring 52 and the second torsion coil spring 54 in a compressed state in the axial direction D, when the weight member 46 moves to one side in the axial direction D of the shoulder bolt 42, the first torsion coil spring 52 is further compressed and the second torsion coil spring 54 is extended but maintained in a compressed state. Therefore, when the weight member 46 vibrates in the axial direction D, the first torsion coil spring 52 and the second torsion coil spring 54 are always in contact with the weight member 46. As a result, abnormal noise generated between the weight member 46 and the first torsion coil spring 52 and the second torsion coil spring 54 can be suppressed.

[0073] Furthermore, by arranging the first torsion coil spring 52 and the second torsion coil spring 54 in a state in which they are biased in the circumferential direction E, when the weight member 46 moves to one side in the circumferential direction E of the stepped bolt 42, the first torsion coil spring 52 is further biased, and the second torsion coil spring 54 maintains its biased state while the biasing force weakens. Therefore, when the weight member 46 vibrates in the circumferential direction E, the first torsion coil spring 52 and the second torsion coil spring 54 are always in contact with the weight member 46. As a result, abnormal noise generated between the weight member 46 and the first torsion coil spring 52 and the second torsion coil spring 54 can be suppressed.

[0074] In other words, in both cases where the weight member 46 moves in the axial direction D of the stepped bolt 42 and where the weight member 46 moves in the circumferential direction E of the stepped bolt 42, abnormal noise generated between the weight member 46 and the first torsion coil spring 52 and the second torsion coil spring 54 can be suppressed.

[0075] In the vibration damping device 40 of this embodiment, the first torsion coil spring 52 arranged on one side of the weight member 46 in the axial direction D and the second torsion coil spring 54 arranged on the other side of the weight member 46 in the axial direction D are formed to have the same shape.

[0076] By making the first torsion coil spring 52 arranged on one side of the weight member in the axial direction D and the second torsion coil spring 54 arranged on the other side have the same shape, the same spring member can be used, which reduces the manufacturing cost of the spring member.

[0077] The vibration damping device 40 of this embodiment is provided on the seat back 14 that supports the upper body of a seated occupant, or on the headrest 16 that supports the head of a seated occupant.

[0078] Meanwhile, the vehicle seat 10 is attached to the vehicle body floor portion 26 via the slide rails 20 and the seat brackets so as to be slidable in the front-rear direction of the vehicle. In other words, since the lower end of the vehicle seat 10 is supported by the slide rails 20, the seat back 14 and the head rest 16 become free ends in the vehicle seat 10 and vibrate more than the seat cushion 12. For this reason, by providing the vibration damping device 40 to the seat back 14 or the head rest 16, which vibrate more than the seat cushion 12, it is possible to effectively absorb the vibration energy of the vehicle seat 10 and improve the damping efficiency for damping the vibration of the vehicle seat 10.

[0079] In the vehicle seat 10 of this embodiment, the vibration damping device 40 is provided on the upper end side of the seat back frame 28 that constitutes the framework of the seat back 14.

[0080] Incidentally, since the seat back 14 has a larger outer shape than the headrest 16, it is easy to ensure a space for installing the vibration damping device 40. By providing the vibration damping device 40 on the upper end side of the seat back frame 28 that constitutes the framework of the seat back 14, it is possible to ensure sufficient space for installing the vibration damping device 40.

[0081] The vibration damping device of the present invention has been described above based on the above embodiment. However, the specific configuration is not limited to this embodiment, and design changes are permitted as long as they do not deviate from the gist of the invention according to each claim in the scope of the claims.

[0082] In the above embodiment, an example has been shown in which the vibration damping device 40 is attached to the bracket 34 so that the axial direction D of the stepped bolt 42 is aligned along the seat width direction. However, as shown in Fig. 10, the vibration damping device 40 may also be attached to the first piece 34A of the bracket 34 so that the axial direction D of the stepped bolt 42 is aligned along the seat front-rear direction when the seat back 14 is in an upright position. Even in this case, it is possible to damp vibrations in the seat width direction and the seat front-rear direction of the vehicle seat 10.

[0083] 12, the vibration damping device 40 may be attached to the bracket 134 so that the axial direction D of the shoulder bolt 42 is aligned along a direction that includes components in the seat width direction, the seat front-rear direction, and the seat up-down direction. In this case, the vehicle seat 10 can damp vibrations that include components in the seat width direction, the seat front-rear direction, and the seat up-down direction of the vehicle seat 10.

[0084] In the above embodiment, an example has been shown in which the spring member is the torsion coil spring 50. However, the spring member is not limited to this embodiment, and may be any member that applies a spring force to the weight member 46 in the axial direction D and the circumferential direction E of the shoulder bolt 42. For example, a spring member that applies a spring force to the weight member 46 in the axial direction D and a spring member that applies a spring force to the weight member 46 in the circumferential direction E may be provided separately.

[0085] In the above embodiment, an example has been shown in which the weight member 46 is formed in a quadrangular prism shape. However, the weight member is not limited to this form, and may also be formed in a cylindrical or polygonal prism shape.

[0086] In the above embodiment, an example was shown in which one vibration damping device 40 was provided in the vehicle seat 10. However, the vehicle seat 10 may be provided with a plurality of vibration damping devices.

[0087] In the above embodiment, an example has been shown in which the vibration damping device 40 is provided at approximately the center in the seat width direction, at the upper end of the upper frame 27. However, the vibration damping device 40 may be provided on the right or left side in the seat width direction, or may be provided on the headrest stay, the lower frame 25, or the cushion frame 18.

[0088] In the above embodiment, an example was shown in which the vibration damping device of the present invention is applied to a vehicle seat, but the vibration damping device of the present invention can also be applied to seats in trains, airplanes, ships, and other vehicles. [Explanation of symbols]

[0089] 10 Vehicle seats 10A Seat frame 40 Vibration damping device 42 Shoulder bolt (an example of a shaft component) 46 Weight member 46A through hole 50 Torsion coil spring (an example of a spring component) 52 First torsion coil spring (an example of a spring member) 52A compression coil section 52B Arm 54 Second torsion coil spring (an example of a spring member) 54A Compression Coil Section 54B Arm D-axis direction E Circumferential direction

Claims

1. A shaft member attached to a seat frame; a weight member having an eccentric through hole through which the shaft member is inserted, the weight member being movable in an axial direction of the shaft member and in a circumferential direction of the shaft member; spring members arranged on both sides of the weight member in the axial direction to enable the weight member to vibrate in the axial direction and the circumferential direction; A vibration damping device comprising:

2. The spring members arranged on both sides of the weight member in the axial direction are provided to urge the weight member in opposite directions to each other in the axial direction and to urge the weight member in opposite directions to each other in the circumferential direction.

2. The vibration damping device of claim 1.

3. The spring member is a torsion coil spring having a spiral compression coil portion and arm portions extending from both ends of the compression coil portion.

3. A vibration damping device according to claim 1 or 2.

4. The torsion coil spring is provided in a state where it is compressed in the axial direction and is biased in the circumferential direction.

4. The vibration damping device of claim 3.

5. The spring member disposed on one side of the weight member in the axial direction and the spring member disposed on the other side of the weight member in the axial direction are formed in the same shape. A vibration damping device according to any one of claims 1 to 4.

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