Vibration Damping Device

Abstract

To reduce costs for processing of a weight member.SOLUTION: A vibration damping device 40 includes: a shoulder bolt 42 attached to a seat frame 10A; a weight member 46 which is formed on an outer peripheral surface along an axial direction D of the shoulder bolt 42, has a first groove part 46A and a second groove part 46B in which the shoulder bolt 42 fits, and may move along the axial direction D; and a first coil spring 48A and a second coil spring 48B provided at both sides of the weight member 46 in the axial direction D.SELECTED DRAWING: Figure 5

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 damper device having a weight with a central through hole, a central guide rod that is inserted into the central through hole of the weight to allow the weight to slide, a right-side central spring that is arranged to the right of the central guide rod, and a left-side central spring that is arranged to the left of the central guide rod. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-108905 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 cost of machining the weight increases because a central through hole is formed in the weight.

[0006] In consideration of the above, an object of the present invention is to provide a vibration damping device that can reduce the cost associated with processing a weight member. [Means for solving the problem]

[0007] The vibration damping device of the present invention as described in claim 1 comprises an axle member attached to a seat frame, a weight member formed on an outer surface along the axial direction of the axle member, having a groove portion into which the axle member fits, and movable along the axial direction, and a coil spring provided on both sides of the weight member in the axial direction.

[0008] According to the present invention described in claim 1, the weight member has a groove on its outer circumferential surface into which the shaft member fits, so that the weight member can move along the axial direction of the shaft member without providing a through hole in the weight member. The groove of the weight member into which the shaft member fits is formed by processing the outer circumferential surface of the weight member, without drilling a through hole in the weight member. As a result, the cost associated with processing the weight member can be reduced.

[0009] In a vibration damping device according to the present invention as set forth in claim 2, in the vibration damping device as set forth in claim 1, two shaft members are provided so as to be point-symmetrical with respect to the center of gravity of the weight member when viewed from the axial direction.

[0010] According to the present invention described in claim 2, two shaft members are provided so as to be point symmetrical with respect to the center of gravity of the weight member, and the shaft members are disposed on either side of the weight member. Therefore, the weight member is moved in the axial direction using the two shaft members as rails. As a result, the weight member is moved in the axial direction stably. Therefore, the weight member performs the desired operation, and the weight member can be vibrated at the target resonant frequency.

[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 groove portion is formed so as to expand in diameter toward the outside of the weight member in a plane perpendicular to the axial direction.

[0012] According to the present invention as set forth in claim 3, the groove is formed so as to expand in diameter toward the outside of the weight member in a plane perpendicular to the axial direction, and therefore an undercut, which is a shape that is shaded when viewed from one direction, is not formed in the groove. Therefore, the groove can be easily formed by cutting. As a result, the processing cost of the weight member can be reduced.

[0013] In the vibration damping device of the present invention described in claim 4, in the vibration damping device described in any one of claims 1 to 3, the weight member has protrusions on both sides in the axial direction that protrude outward along the axial direction, and the coil spring is arranged to fit into the protrusions.

[0014] According to the present invention as set forth in claim 4, the coil spring is provided so as to fit into the protruding portion of the weight member, and the inside of the coil spring is supported by the protruding portion. Therefore, the coil spring can be positioned relative to the weight member. As a result, the weight member performs the desired operation, and the weight member can be vibrated at the target resonant frequency. Effect of the Invention

[0015] According to the vibration damping device of the present invention, the cost associated with processing the weight member can be reduced. [Brief description of the drawings]

[0016] [Figure 1] 1 is a perspective view of a vehicle seat according to a first embodiment, 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 a first embodiment, 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 a first embodiment 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 a first embodiment; [Diagram 5] 4 is a cross-sectional view showing the vibration damping device according to the first embodiment, showing the AA cross section of FIG. 3. [Figure 6] 4 is a cross-sectional view showing the vibration damping device according to the first embodiment, showing the cross section taken along line BB in FIG. 3. [Figure 7] FIG. 2 is a schematic diagram showing a vibration model of the vibration damping device according to the first embodiment. [Figure 8]8A and 8B are cross-sectional views illustrating the operation of the vibration damping device according to the first embodiment, in which FIG. 8(A) shows a state in which the weight member has moved to one end side, and FIG. 8(B) shows a state in which the weight member has moved to the other end side. [Figure 9] 5 is a cross-sectional view showing a state in which an outer circumferential surface of the weight member according to the first embodiment is being machined. FIG. [Figure 10] FIG. 6 is a cross-sectional view showing a vibration damping device according to a second embodiment. [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. [Figure 12] 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

[0017] [First embodiment] The vibration damping device according to the first 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 vertical 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. Hereinafter, when the directions of the front-rear, the up-down, and the left-right are simply used for the description, they indicate the front-rear, the up-down, and the left-right of the vehicle seat 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 are relative 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.

[0018] The vibration damping device of the first embodiment will be described as being applied to a vehicle seat provided in a vehicle.

[0019] [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.

[0020] 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.

[0021] 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 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] As shown in FIG. 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.

[0026] [Configuration of vibration damping device] As shown in FIG. 4, the vibration damping device 40 includes a shoulder bolt 42 serving as a shaft member, a collar member 44, a weight member 46, a coil spring 48, a first plate member 52, and a second plate member 54.

[0027] (weight member 46) 4 and 5, the weight member 46 is made of metal and formed into a cylindrical shape. The weight member 46 has a first groove portion 46A and a second groove portion 46B as groove portions formed on the outer circumferential surface, and a first protruding portion 46C and a second protruding portion 46D as protruding portions formed on both ends in the axial direction D.

[0028] 6, the first groove portion 46A and the second groove portion 46B are formed to be point symmetrical with respect to the center of gravity P1 of the weight member 46 when viewed from the axial direction D. In other words, the first groove portion 46A and the second groove portion 46B are provided on both sides of the center of gravity P1 of the weight member 46 when viewed from the axial direction D. Note that the first groove portion 46A and the second groove portion 46B have substantially the same configuration except for the positions at which they are formed, and therefore the following description will mainly focus on the first groove portion 46A.

[0029] The first groove portion 46A is formed in a groove shape recessed from the outer circumferential surface of the weight member 46 toward the radially inward side of the weight member 46. The first groove portion 46A is formed in a groove shape whose approximately semicircular shape in a plane perpendicular to the axial direction D extends in the axial direction D. The first groove portion 46A is formed so as to expand in diameter toward the radially outward side of the weight member 46 in the plane perpendicular to the axial direction D.

[0030] The stepped bolt 42 is fitted into the first groove portion 46A and the second groove portion 46B via the collar member 44. The weight member 46 is configured to be movable in the axial direction D along the collar member 44.

[0031] As shown in Figs. 4 and 5, the first protrusion 46C is formed in a cylindrical shape protruding from an end face on the other end side in the axial direction D toward the other end side along the axial direction D. The axis of the first protrusion 46C is provided so as to coincide with the axis of the weight member 46. The outer diameter of the first protrusion 46C is formed to be approximately the same as the inner diameter of the coil spring 48. The second protrusion 46D is formed in a cylindrical shape protruding from an end face on one end side in the axial direction D toward one end side along the axial direction D. The outer diameter of the second protrusion 46D is formed to be approximately the same as the inner diameter of the coil spring 48.

[0032] (Shoulder bolt 42) As shown in Figures 4 and 5, the stepped bolt 42 is made of metal and has a shaft portion 42A, a male thread portion 42C formed on one end side of the shaft portion 42A, and a head portion 42B formed on the other end side of the shaft portion 42A.

[0033] As shown in Fig. 6, two stepped bolts 42 are provided so as to be point symmetrical with respect to the center of gravity P1 of the weight member 46 when viewed from the axial direction D. The two stepped bolts 42 are provided on both sides of the center of gravity P1 of the weight member 46 when viewed from the axial direction D. As shown in Figs. 5 and 6, one stepped bolt 42 fits into the first groove portion 46A via a collar member 44, and the other stepped bolt 42 fits into the second groove portion 46B via the collar member 44.

[0034] The shaft portion 42A is formed in a cylindrical shape. The length of the shaft portion 42A in the axial direction D is formed to be longer than the weight member 46. The male screw portion 42C is cylindrical with an outer diameter smaller than that of the shaft portion 42A, and has a screw thread formed on the outer circumferential surface. The head portion 42B is cylindrical with an outer diameter larger than that of the shaft portion 42A.

[0035] (Colored material 44) As shown in FIG. 4 and FIG. 5, 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 length of the collar member 44 in the axial direction D is formed to be approximately the same as the length 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. The collar member 44 is also interposed between the shaft portion 42A and the coil spring 48.

[0036] (First plate member 52) 4 and 5, the first plate member 52 is provided on the other end side of the weight member 46 in the axial direction D via a first coil spring 48A described later. The first plate member 52 is formed in a generally diamond-shaped plate having a larger outer shape than the weight member 46 when viewed from the axial direction D. The first plate member 52 may be made of metal. The first plate member 52 includes a protrusion 52A and a through hole 52B.

[0037] The protrusion 52A is formed in a cylindrical shape protruding toward one end side along the axial direction D. The axis of the protrusion 52A is provided to coincide with the axis of the weight member 46. The outer diameter of the protrusion 52A is formed to be approximately the same as the inner diameter of the coil spring 48.

[0038] Two through holes 52B are provided corresponding to the positions where the two stepped bolts 42 are installed. The through holes 52B are formed penetrating the first plate member 52 in the plate thickness direction. The inner diameter of the through holes 52B is formed to be substantially the same as the outer diameter of the shaft portion 42A. The shaft portion 42A of the stepped bolt is inserted into the through holes 52B.

[0039] (Second plate member 54) The second plate member 54 is provided on one end side of the weight member 46 in the axial direction D via a second coil spring 48B described later. The second plate member 54 is formed in a generally diamond-shaped plate having a larger outer shape than the weight member 46 when viewed from the axial direction D. The second plate member 54 may be made of metal. The second plate member 54 includes a protrusion 54A and a screw hole 54B.

[0040] The protrusion 54A is formed in a cylindrical shape protruding toward the other end side along the axial direction D. The axis of the protrusion 54A is provided to coincide with the axis of the weight member 46. The outer diameter of the protrusion 54A is formed to be approximately the same as the inner diameter of the coil spring 48.

[0041] Two screw holes 54B are provided corresponding to the positions where the two stepped bolts 42 are installed. The screw holes 54B penetrate the second plate member 54 in the plate thickness direction, and have female threads formed on the inner circumferential surface. The male threaded portion 42C of the stepped bolt 42 is adapted to be attached to the screw holes 54B of the second plate member 54.

[0042] (coil spring 48) 4 and 5, the coil springs 48 are provided on both sides of the weight member 46 in the axial direction D. The coil springs 48 include a first coil spring 48A and a second coil spring 48B.

[0043] The first coil spring 48A is disposed on the other end side of the weight member 46. In a compressed state, the first coil spring 48A is disposed between an end face on the other end side of the weight member 46 and an end face on one end side of the first plate member 52. One end side of the first coil spring 48A in the axial direction D is fitted into the first protruding portion 46C. The other end side of the first coil spring 48A in the axial direction D is fitted into the convex portion 52A of the first plate member 52.

[0044] The second coil spring 48B is disposed on one end side of the weight member 46. In a compressed state, the second coil spring 48B is disposed between an end face on one end side of the weight member 46 and an end face on the other end side of the second plate member 54. One end side of the second coil spring 48B in the axial direction D is fitted into the convex portion 54A of the second plate member 54. The other end side of the second coil spring 48B in the axial direction D is fitted into the second protruding portion 46D.

[0045] The weight member 46 is biased toward one end by the first coil spring 48A and toward the other end by the second coil spring 48B. Elastic energy (biasing force) is stored in the first coil spring 48A and the second coil spring 48B. As a result, the weight member 46 is disposed at approximately the center of the axial direction D of the shaft portion 42A of the stepped bolt 42. In other words, the weight member 46 is subjected to so-called forced vibration, in which the biasing forces of the first coil spring 48A and the second coil spring 48B act.

[0046] 3, the vibration damping device 40 formed in this manner is attached to the bracket 34 by attaching a nut 43 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.

[0047] 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.

[0048] [Natural frequency of weight member] The natural frequency of the weight member 46 is set to be the same as the resonance frequency of the vehicle seat 10. As shown in FIG. 7, the spring constant k1 of the first coil spring 48A and the spring constant k2 of the second coil spring 48B are set so that the resonance frequency of the vehicle seat 10 and the natural frequency of the weight member 46 are the same. 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 the first 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 coil spring 48A and the spring constant k2 of the second coil spring 48B are set so that the natural frequency f of the weight member 46 is set to the resonance frequency of the vehicle seat 10.

[0049] [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 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 coil spring 48B is compressed, and the first coil spring 48A 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 coil spring 48A is compressed, and the second coil spring 48B is expanded but maintained in a compressed state.

[0050] In this way, the weight member 46 reciprocates along the collar member 44 in the axial direction D due to the first coil spring 48A and the second coil spring 48B, and resonates. That is, vibration energy due to vibration at the resonant frequency 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 of the vehicle seat 10 is absorbed, and the vibration of the vehicle seat 10 is damped.

[0051] [Actions and Effects of the First Embodiment] Next, the operation and effects of the vibration damping device 40 of the first embodiment will be described.

[0052] The vibration damping device 40 of the first embodiment comprises a stepped bolt 42 attached to a seat frame 10A, a weight member 46 formed on the outer peripheral surface along the axial direction D of the stepped bolt 42, having a first groove portion 46A and a second groove portion 46B into which the stepped bolt 42 fits, and capable of moving along the axial direction D, and a first coil spring 48A and a second coil spring 48B provided on both sides of the weight member 46 in the axial direction D.

[0053] The weight member 46 has a first groove portion 46A and a second groove portion 46B that are formed along the axial direction D of the stepped bolt 42 and into which the stepped bolt 42 fits, allowing the weight member 46 to move in the axial direction D of the stepped bolt 42. The natural frequency of the weight member 46 is set to correspond to the resonance frequency of the vehicle seat 10, so that the weight member 46 resonates with the resonance of the vehicle seat 10. This converts the vibration energy of the vehicle seat 10 into the vibration energy of the weight member 46. As a result, the vibration energy of the vehicle seat 10 is absorbed, and the vibration of the vehicle seat 10 is effectively damped.

[0054] Moreover, by providing the first groove portion 46A and the second groove portion 46B, into which the stepped bolt 42 fits, on the outer circumferential surface of the weight member 46, the weight member 46 can move along the axial direction D of the stepped bolt 42 without providing a through hole in the weight member 46. Therefore, the first groove portion 46A and the second groove portion 46B of the weight member 46, into which the stepped bolt 42 fits, are formed by machining the outer circumferential surface of the weight member 46, without performing hole machining to open a through hole in the weight member 46. As a result, the machining cost of the weight member 46 can be reduced, and the cost of the vibration damping device 40 can be reduced.

[0055] Incidentally, when forming a through hole in the weight member 46, the length of the processing tool (e.g., an end mill) increases, and therefore the processing tool may be deformed during processing. In that case, the through hole formed by the hole processing may not have the desired shape.

[0056] In the first embodiment, as shown in Fig. 7, the first groove portion 46A and the second groove portion 46B are formed by processing the outer peripheral surface of the weight member 46 with the processing tool 60. Therefore, it is possible to use a processing tool 60 having a shorter length than in the case of drilling holes. As a result, deformation of the processing tool 60 is suppressed, and processing accuracy can be improved.

[0057] In addition, a coil spring is used as the biasing member that biases the weight member 46. Therefore, the stroke of the weight member 46 can be made longer than when a rubber member is used as the biasing member. As a result, the kinetic energy of the weight member 46 can be increased. Therefore, the vibration damping device 40 can be made compact and lightweight with a simple configuration.

[0058] In the vibration damping device 40 of the first embodiment, two shoulder bolts 42 are provided so as to be point-symmetrical with respect to the center of gravity P1 of the weight member 46 when viewed in the axial direction D.

[0059] By providing two stepped bolts 42 so as to be point-symmetrical with respect to the center of gravity P1 of the weight member 46, the stepped bolts 42 are disposed on either side of the weight member 46. Therefore, the weight member 46 is moved in the axial direction D using the two stepped bolts 42 as rails. As a result, the weight member 46 is moved stably in the axial direction. Therefore, the weight member 46 performs the desired operation, and the weight member 46 can be vibrated at the targeted resonant frequency.

[0060] In the vibration damping device 40 of the first embodiment, the stepped bolt 42 is formed so as to increase in diameter toward the outside of the weight member 46 in a plane perpendicular to the axial direction D.

[0061] In a plane perpendicular to the axial direction D, the first groove portion 46A and the second groove portion 46B are formed so as to expand in diameter toward the outside of the weight member 46, so that undercuts, which are shapes that are shaded when viewed from one direction, are not formed in the first groove portion 46A and the second groove portion 46B. Therefore, as shown in Fig. 7, the first groove portion 46A and the second groove portion 46B are easily formed by the processing tool 60. As a result, the processing cost of the weight member 46 can be reduced.

[0062] In the first embodiment of the vibration damping device 40, the weight member 46 has a first protrusion 46C and a second protrusion 46D on both sides in the axial direction D, which protrude outward along the axial direction D, and the first coil spring 48A is adapted to fit into the first protrusion 46C, and the second coil spring 48B is adapted to fit into the second protrusion 46D.

[0063] The first coil spring 48A is fitted into the first protruding portion 46C of the weight member 46, and the second coil spring 48B is fitted into the second protruding portion 46D of the weight member 46, so that the insides of the first coil spring 48A and the second coil spring 48B are supported by the protruding portions. Therefore, the first coil spring 48A and the second coil spring 48B can be positioned with respect to the weight member 46. As a result, the weight member 46 performs the desired operation, and the weight member 46 can be vibrated at a target resonant frequency.

[0064] In the vibration damping device 40 of the first embodiment, the coil spring 48 is arranged in a compressed state.

[0065] By disposing the coil springs 48 in a compressed state, when the weight member 46 moves along the shoulder bolt 42, one of the coil springs 48 is further compressed, while the other coil spring 48 is expanded but maintained in a compressed state. Therefore, when the weight member 46 vibrates, the coil springs 48 are always in contact with the weight member 46. As a result, abnormal noise generated between the weight member 46 and the coil springs 48 can be suppressed.

[0066] The vibration damping device 40 of the first 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.

[0067] 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.

[0068] In the vehicle seat 10 of the first embodiment, the natural frequency of the weight member 46 is set to be the same as the resonant frequency of the vehicle seat 10.

[0069] By setting the natural frequency of the weight member 46 to be the same as the resonance frequency of the vehicle seat 10, the weight member 46 resonates with the resonance of the vehicle seat 10. This converts the vibration energy of the vehicle seat 10 into the vibration energy of the weight member 46. As a result, the vibration energy of the vehicle seat 10 is absorbed, and the vibration of the vehicle seat 10 is effectively damped.

[0070] In the vehicle seat 10 of the first 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.

[0071] 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.

[0072] In the vehicle seat 10 of the first embodiment, the shoulder bolt 42 is disposed along the seat width direction.

[0073] By arranging the stepped bolt 42 along the seat width direction, vibrations of the vehicle seat 10 along the seat width direction can be damped.

[0074] Second Embodiment The vibration damping device of the second embodiment differs from the vibration damping device of the first embodiment in that the configuration of the shaft member is different.

[0075] [Configuration of vibration damping device] The configuration of the vibration damping device of the second embodiment will be described below. Note that the same terms or symbols will be used to describe the same or equivalent parts as those described in the first embodiment.

[0076] 10, the vibration damping device 140 includes three shoulder bolts 42 as shaft members. The weight member 146 includes a first groove portion 146A, a second groove portion 146B, and a third groove portion 146C as grooves formed on the outer circumferential surface.

[0077] The first groove portion 146A, the second groove portion 146B, and the third groove portion 146C are disposed evenly in the circumferential direction of the weight member 146 with respect to a center of gravity P1 of the weight member 146 when viewed in the axial direction D.

[0078] The stepped bolt 42 is fitted into the first groove portion 146A, the second groove portion 146B, and the third groove portion 146C via the collar member 44. The weight member 146 is configured to be movable in the axial direction D along the collar member 44.

[0079] In the vibration damping device 140 configured as above, the weight member 146 is supported by three shoulder bolts 42. Therefore, the weight member 146 is more stably moved in the axial direction D. As a result, the weight member 146 performs the desired operation, and the weight member 146 can be vibrated at the target resonance frequency. Note that other configurations and functions and effects are substantially the same as those of the above embodiment, and therefore description thereof will be omitted.

[0080] The vibration damping device of the present invention has been described above based on the above-mentioned embodiments. However, the specific configuration is not limited to these embodiments, 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.

[0081] In the above embodiment, an example has been shown in which the vibration damping device 40, 140 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. 11, 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. In this case, vibrations along the seat front-rear direction of the vehicle seat 10 can be damped.

[0082] 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.

[0083] 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.

[0084] 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.

[0085] In the first embodiment, an example has been shown in which the vibration damping device 40 includes two stepped bolts 42, and in the second embodiment, the vibration damping device 140 includes three stepped bolts 42. However, the vibration damping device may include one stepped bolt 42, or four or more stepped bolts 42.

[0086] In the above embodiment, an example has been shown in which the weight member 46 is formed in a cylindrical shape. However, the weight member is not limited to this form, and may be, for example, a rectangular parallelepiped, a spherical shape, a polygonal prism shape, or other shapes.

[0087] 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 of trains, airplanes, ships, and other vehicles. [Explanation of symbols]

[0088] 10 Vehicle seats 10A Seat frame 40 Vibration damping device 42 Shoulder bolt (an example of a shaft component) 46 Weight member 46A First Groove (An example of a groove) 46B Second groove portion (an example of a groove portion) 46C First protrusion (an example of a protrusion) 46D Second protrusion (an example of a protrusion) 48A First coil spring (an example of a coil spring) 48B Second coil spring (an example of a coil spring)

Claims

1. A shaft member attached to a seat frame; a weight member that is formed on an outer peripheral surface of the shaft member along an axial direction, the weight member having a groove into which the shaft member is fitted, and that is movable along the axial direction; A coil spring provided on both sides of the weight member in the axial direction; A vibration damping device comprising:

2. The shaft member is provided in two pieces so as to be point symmetrical with respect to the center of gravity of the weight member when viewed in the axial direction.

2. The vibration damping device of claim 1.

3. The groove is formed so as to expand in diameter toward the outside of the weight member in a plane perpendicular to the axial direction.

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

4. The weight member includes protrusions protruding outward along the axial direction on both sides in the axial direction, The coil spring is provided to fit into the protruding portion. A vibration damping device according to any one of claims 1 to 3.

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