Dynamic Damper

Abstract

To provide a dynamic damper suppressing degradation in productivity of constituting members, and capable of achieving improvement of assembly operation efficiency and reduction of costs.SOLUTION: A dynamic damper 1 includes: a U-shaped outside fitting 3 having both side walls 9; a U-shaped inside fitting 4 arranged inside the outside fitting and having both side pieces 11 facing the both side walls; four elastic bodies 5 vulcanized and adhered to between the both side walls of the outside fitting and the both side pieces of the inside fitting; a rectangular mass member 6 arranged inside the inside fitting; and a pair of fastening bolts 7 for fixing the mass member to the inside fitting. There are provided: bolt insertion holes 9b penetratingly formed in the both side walls; insertion holes 11a penetratingly formed in the both side pieces; and female screw holes 6a formed in both side portions of the mass member and screwed and fixed with male screw potions 13b of the fastening bolts. The mass member is connected and fixed to the inside fitting with the fastening bolts inserted via the insertion hole of the outside fitting.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a dynamic damper that is attached to a vibration source, such as the body of an automobile, to damp vibrations of a specific frequency. [Background technology]

[0002] A known conventional dynamic damper is disclosed in Patent Document 1 below.

[0003] As shown in Figures 5(a) and (b), this dynamic damper 30 has an outer metal fitting 31 with a U-shaped cross section which is attached to the vibration source of the vehicle, a weight 32 made of a substantially rectangular metal material which is arranged inside the outer metal fitting 31, and four upper and lower pairs of first and second rubber elastomers 33 and 34 which are integrally provided on upper and lower opposing surfaces of the weight 32 which face the upper and lower surfaces, respectively, of the outer metal fitting 31.

[0004] The outer metal fitting 31 has a bottom wall portion 31a, a first side wall portion 31b and a second side wall portion 31c which are integrally provided on the upper and lower side edges of the bottom wall portion 31a, and a first mounting piece 31d which extends upward and a second mounting piece 31e which extends downward which are integrally provided on the outer end edges of the first and second side wall portions 31b, 31c. A plurality of bolt holes 35 are formed in the first and second mounting pieces 31d, 31e, and the dynamic damper 30 is attached to the seat back by a plurality of bolts (not shown) which are inserted into the bolt holes 35.

[0005] A first elongated hole 36 and a second elongated hole 37 are formed penetrating the first side wall portion 31b and the second side wall portion 31c of the outer metal fitting 31 at positions offset in the front-rear direction.

[0006] On the other hand, the weight 32 has a rubber film covering the entire surface, and a first insertion hole 32a and a second insertion hole 32b are formed on the upper and lower opposing surfaces at positions corresponding to the first long hole 36 and the second long hole 37, respectively.

[0007] A first pin member 38 and a second pin member 39 made of rubber are inserted into the first elongated hole 36 and the second elongated hole 37 and are adhesively fixed into the first insertion hole 32a and the second insertion hole 32b without any gaps. The first pin member 38 and the second pin member 39 are arranged in a non-contact state with the first elongated hole 36 and the second elongated hole 37 in a normal state, and are configured to move the weight 32 only in the fore-and-aft direction of the vehicle body (X direction) along the first and second elongated holes 36, 37 in response to vibration, thereby preventing the weight 32 from falling off the outer metal fitting 31.

[0008] The first and second elastic bodies 33, 34 are formed in a columnar shape having an approximately square cross section, with one end of each fixed to the inner surface of the first and second side wall portions 31b, 31c of the outer metal fitting 31, and the other end fixed to the upper and lower surfaces of the weight 32, respectively, by vulcanization adhesion.

[0009] With these configurations, even if the weight 32 moves in the X direction, it is possible to suppress the weight 32 from swinging in the Y direction perpendicular to the X direction with the first and second elastic bodies 33, 34 as fulcrums. Therefore, it is possible to suppress the occurrence of distortion in each of the first and second elastic bodies 33, 34. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Patent No. 4857216 (Fig. 1, Fig. 2) Summary of the Invention [Problem to be solved by the invention]

[0011] However, in the dynamic damper described in Patent Document 1, the entire surface of the weight 32 is integrally coated with a rubber film. Therefore, if the outer shape of the weight 32 is enlarged in order to increase the mass of the weight 32, the molded product produced during vulcanization molding with the rubber film will become larger, limiting the number of pieces that can be molded at one time and lengthening the vulcanization time, which may reduce productivity.

[0012] Furthermore, the first pin member 38 and the second pin member 39 are provided separately, and when assembling the weight 32 to the outer metal fitting 31, in the final process the first and second pin members 38, 39 are fixed to the respective insertion holes 32a, 32b of the weight 32 via the respective long holes 36, 37 of the outer metal fitting 31. This increases the number of assembly steps and parts, which may result in a decrease in assembly efficiency and a rise in costs.

[0013] The present invention has been devised in consideration of the technical problems associated with the conventional dynamic dampers described above, and provides a dynamic damper which suppresses decline in productivity of the components and reduces the number of assembly steps and parts, thereby improving assembly work efficiency and reducing costs. [Means for solving the problem]

[0014] The invention according to claim 1 of the present application comprises an outer member attached to a vibration source and having a pair of left and right side walls, an inner member arranged inside the outer member and having both side pieces facing the both side walls, a plurality of elastic bodies vulcanized and bonded between the inner surfaces of both side walls of the outer member and the outer surfaces of the both side pieces of the inner member, a mass member arranged inside the inner member, and a pair of connecting members for fixing the mass member to the inner member, the outer member has insertion holes formed through both side walls thereof, and through which the connecting members are inserted; the inner member has insertion holes formed through both side pieces thereof, and through which the shafts of the connecting members are inserted; and a pair of fixing holes formed on both sides of the mass member, and into which the tips of the shafts of the connecting members inserted through the insertion holes are fixed; the mass member is connected and fixed to the inner member by the connecting members inserted through the insertion holes of the outer member; The elastic bodies are disposed on both side walls of the outer member and at four corners of both side pieces of the inner member, each of the insertion holes on both side walls of the outer member is formed at a position avoiding the elastic body, and a recess is formed around each of the insertion holes, recessed toward the inner member; With the tip of the connecting member fixed to the fixing hole of the mass member, the head of the connecting member is disposed inside the recess. It is characterized by the following. Effect of the Invention

[0015] According to the present invention, it is possible to suppress a decrease in the productivity of components of a dynamic damper, and to improve the efficiency of assembly work and reduce costs by reducing the number of assembly steps and parts. [Brief description of the drawings]

[0016] [Figure 1] 1 is an overhead view showing a front suspension member of an automobile to which a dynamic damper according to the present invention is attached; [Diagram 2] FIG. 2 is a plan view of the dynamic damper of the present embodiment. [Diagram 3] 3 is a cross-sectional view taken along line AA in FIG. 2. [Figure 4] FIG. 2 is a right side view of the dynamic damper. [Diagram 5] 1A and 1B show a conventional dynamic damper attached to a vehicle seat back, where (a) is a view from the front of the vehicle and (b) is a view from below. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A dynamic damper according to an embodiment of the present invention will now be described with reference to the drawings. In this embodiment, the dynamic damper is applied to a front suspension member of an automobile.

[0018] FIG. 1 is a perspective view showing a front suspension member of an automobile to which a dynamic damper according to the present invention is attached.

[0019] As is well known, the front suspension member 01, which is a source of vibration in an automobile, suppresses twisting of the body while driving, absorbs shocks from the road surface, and improves ride comfort and handling stability, and is composed of a square frame 02 formed from highly rigid hot-rolled steel plate for welded structures, as shown in Figure 1. This front suspension member 01 supports the engine, steering, etc. in addition to the front suspension.

[0020] The dynamic damper 1, which is a vibration suppression device, is attached to the front suspension member 01 at a position indicated by an arrow in FIG.

[0021] FIG. 2 is a plan view of the dynamic damper of this embodiment, FIG. 3 is a cross-sectional view taken along line AA in FIG. 2, and FIG. 4 is a right side view of the dynamic damper.

[0022] As shown in FIG. 2, the dynamic damper 1 comprises a mounting bracket 2 that is directly fixed to the frame 02 of the front suspension member 01, which is a vibration source, an outer metal fitting 3 that is an outer member that is attached to the frame 02 via the mounting bracket 2, an inner metal fitting 4 that is an inner member that is arranged inside the outer metal fitting 3, a plurality of rubber elastic bodies 5 (four in this embodiment) that are arranged and fixed between the outer metal fitting 3 and the inner metal fitting 4, a mass member 6 that is a mass member that is arranged inside the inner metal fitting 4, and fastening bolts 7, 7 that are a pair of connecting members that connect and fix the mass member 6 to the inner metal fitting 4.

[0023] As shown in Figures 2 and 3, this dynamic damper 1 is arranged so that the up-down direction (arrow X direction) in Figure 3 corresponds to the up-down direction of the vehicle body, the left-right direction (arrow Y direction) corresponds to the width direction of the vehicle body, and the front-to-rear direction (arrow Z direction) in Figure 2 approximately corresponds to the front-to-rear direction of the vehicle body.

[0024] The mounting bracket 2 is formed of a metal plate in a rectangular shape extending in the vehicle body width direction in the direction of arrow Y, and at the center positions of the front and rear ends are formed bolt insertion holes 2a, 2b through which fixing bolts (not shown) for fixing to the frame 02 of the front suspension member 01 are inserted.

[0025] The outer metal fitting 3 is formed by bending a metal plate into a U-shape, and has a bottom wall 8 fixed to the upper surface of the mounting bracket 2, and a pair of side walls 9, 9 rising from both longitudinal edges of the bottom wall 8. The bottom wall 8 is fixed to the upper surface of the mounting bracket 2 by, for example, welding.

[0026] The side walls 9, 9 have recesses 9a, 9a recessed toward the inner metal fitting 4 at approximately the center in the up-down and left-right directions. Each recess 9a, 9a is formed along the width direction of the side walls 9, 9 and has a vertical cross section that is approximately U-shaped. The depth of each recess 9a, 9a is deeper than the outer surface of the heads 12, 12 of the fastening bolts 7, 7. In other words, as described later, the depth is set so that when the fastening bolts 7, 7 are screwed into the mass member 6, the heads 12, 12 are accommodated and disposed within the recesses 9a, 9a. The bottom of each recess 9a, 9a has a bolt insertion hole 9b, 9b through which the shafts 13, 13 of the fastening bolts 7, 7 can be inserted, formed at the center in the longitudinal direction.

[0027] The inner metal fitting 4, like the outer metal fitting 3, is formed by bending a metal plate into a U-shape, and has a bottom 10 arranged parallel to the bottom wall 8 of the outer metal fitting 3, and a pair of side pieces 11, 11 rising up from both longitudinal edges of the bottom 10.

[0028] The inner fitting 4 is formed such that the thickness W1 of the plate material is thinner than the thickness W of the outer fitting 3, and is disposed inside the outer fitting 3 in the same orientation with a specified gap. That is, the bottom 10 of the inner fitting 4 is disposed parallel to the bottom wall 8 of the outer fitting 3 with a specified gap, and the two side pieces 11, 11 are disposed parallel to both side walls 9, 9 of the outer fitting 3 with a certain gap C between them.

[0029] The side pieces 11, 11 have insertion holes 11a, 11a formed at approximately the center thereof through which small-diameter male threaded portions 13b, 13b provided at the tips of the shaft portions 13, 13 of the fastening bolts 7, 7 described below are inserted.

[0030] 2 and 3, each of the four elastic bodies 5 has a substantially hand drum-shaped cross section and extends in the width direction (Z direction) of the outer metal fitting 3 and the inner metal fitting 4, forming a substantially elliptical vertical cross section. The elastic bodies 5 are disposed at the four corners of both side walls 9, 9 of the outer metal fitting 3 and both side pieces 11, 11 of the inner metal fitting 4, that is, disposed at the four corners at a predetermined distance from each other in the directions of the arrow X and the arrow Z. The two ends of each elastic body 5 in the direction of the arrow Y are vulcanized and bonded to the inner surfaces of the both side walls 9, 9 and the outer surfaces of the both side pieces 11, 11, and each is formed to have a substantially elliptical, thick cross section extending in the Z direction, so that it is tuned to a vibration with a relatively medium frequency and small amplitude.

[0031] The size of the cross-sectional shape of this elastic body 5 can be changed as desired depending on the object to which the dynamic damper 1 is attached, that is, the frequency of vibration to be reduced.

[0032] The mass member 6 is formed, for example, from an iron-based metal material into a substantially rectangular prism and has a predetermined mass, with its length L in the Y direction (vehicle width direction) being slightly smaller than the distance between both side pieces 11, 11 of the inner metal fitting 4, and its length L1 in the Z direction (vehicle front-rear direction) being larger than the length of the inner metal fitting 4 in the Z direction, and is housed within the inner metal fitting 4.

[0033] The mass member 6 is also formed on both sides with a pair of female threaded holes 6a, 6a which are fixing holes into which the male threaded portions 13b, 13b of the fastening bolts 7, 7 are screwed. These female threaded holes 6a, 6a are formed coaxially from both side surfaces of the mass member 6 toward the center of gravity P of the mass member 6.

[0034] The size and shape of the mass member 6 can be changed as desired according to the specific frequency of the vibration source.

[0035] The fastening bolts 7, 7 are made of an iron-based metal material, and have heads 12, 12 and shafts 13, 13 formed integrally with the heads 12, 12.

[0036] 3 and 4, the heads 12, 12 are formed in a flat disk shape, and are formed at the center of their outer surfaces with hexagonal grooves 12a, 12a into which the tip of a hexagonal wrench (not shown), which is a screwing tool, is fitted. The heads 12, 12 are also formed so that their outer diameter is larger than the inner diameter of the bolt insertion holes 9b, 9b of the outer fitting 3.

[0037] The shaft portions 13, 13 have cylindrical large diameter portions 13a, 13a provided at the base side of the heads 12, 12, and male thread portions 13b, 13b having a smaller diameter than the large diameter portions 13a, 13a and integrally formed at the tip portions of the large diameter portions 13a, 13a.

[0038] The outer diameter of each of the large diameter portions 13a, 13a is formed to be smaller than the inner diameter of the bolt insertion holes 9b, 9b of the outer fitting 3 and larger than the inner diameter of each of the insertion holes 11a, 11a of the inner fitting 4.

[0039] The male threaded portions 13b, 13b are formed so that their outer diameter is slightly smaller than the inner diameter of each insertion hole 11a, 11a of the inner fitting 4, and are capable of being screwed into each female threaded hole 6a, 6a of the mass member 6 via each insertion hole 11a, 11a. Moreover, each male threaded portion 13b, 13b is formed so that its axial length is shorter than the length of each female threaded hole 6a, 6a.

[0040] In addition, when each male threaded portion 13b, 13b is screwed into each female threaded hole 6a, 6a, the annular end faces 13c, 13c on the male threaded portion 13b, 13b side abut (seat) on the hole edge of each insertion hole 11a, 11a, thereby regulating the maximum screwing amount of the fastening bolts 7, 7.

[0041] In addition, each of the fastening bolts 7, 7 connects the mass member 6 to the inner fitting 4 by screwing each of the male threaded portions 13b, 13b into each of the female threaded holes 6a, 6a of the mass member 6, and also prevents the mass member 6 from falling off inadvertently.

[0042] Each of the elastic bodies 5 is provided at a position where the elastic center of each of the elastic bodies 5 coincides or nearly coincides with the center of gravity P of the mass member 6 with respect to the vibration of translational movement in the vehicle body up-down direction (X direction), vehicle body width direction (Y direction), and vehicle body fore-aft direction (Z direction) from the front suspension member 01, which is the vibration source, relative to the dynamic damper 1. [Function and effect of the dynamic damper in this embodiment] The effects of the dynamic damper 1 of this embodiment, which is configured as described above, will be described below.

[0043] According to the dynamic damper 1 of this embodiment, the elastic bodies 5 are previously vulcanized and bonded between the outer metal fitting 3 and the inner metal fitting 4, and the outer metal fitting 3 and the inner metal fitting 4 are connected via the elastic bodies 5. In this state, the bottom wall 8 of the outer metal fitting 3 is attached to the upper surface of the mounting bracket 2 by welding, and in this state, the large diameter portions 13a, 13a of the shafts of the fastening bolts 7, 7 are inserted into the bolt insertion holes 9b, 9b of the outer metal fitting 3. Thereafter, the male threaded portions 13b, 13b of the shafts 13, 13 are inserted into the insertion holes 11a, 11a of the inner metal fitting 4 and lightly screwed into the female threaded holes 6a, 6a on both the left and right sides of the mass member 6.

[0044] Next, the hexagonal wrench fitted into the hexagonal grooves 12a, 12a of the heads 12, 12 of the fastening bolts 7, 7 is rotated to screw the male threaded portions 13b, 13b into the female threaded holes 6a, 6a and tighten the bolts 7, 7. This causes the mass member 6 to be firmly fastened to the inner fitting 4.

[0045] As the fastening bolts 7, 7 are screwed in, the end faces 13c, 13c of the large diameter portions 13a, 13a come into contact (seat) with the hole edges of the insertion holes 11a, 11a, thereby restricting further screwing in. In other words, the maximum tightening amount of the fastening bolts 7, 7 is restricted.

[0046] In addition, in this state, the fastening bolts 7, 7 have heads 12, 12 housed in the respective recesses 9a, 9a of the outer fitting 3, as shown in FIG. 3, and therefore the heads 12, 12 do not protrude from the outer surfaces of the respective side walls 9, 9 of the outer fitting 3.

[0047] Next, by attaching and fixing the mounting bracket 2 to the front suspension member 01 with two fixing bolts, the dynamic damper 1 can be reliably fixed to the front suspension member 01 at a predetermined position.

[0048] As described above, in this embodiment, since the outer surface of the mass member is not coated with a rubber film as in the prior art, the number of pieces that can be molded at one time is not limited even if the mass, i.e., the volume, of the mass member 6 is increased, and the vulcanization time can be shortened, thereby suppressing a decrease in productivity.

[0049] Moreover, the fastening bolts 7, 7 that secure the mass member 6 to the inner metal fitting 4 that is integrally joined with the outer metal fitting 3 can also be used to prevent the mass member 6 from falling off, which reduces the number of assembly steps and parts, improving the efficiency of the assembly work and reducing costs. In other words, preventing the mass member 6 from falling off means that even if the four elastic bodies 5 are broken while the vehicle is running due to deterioration over time or long-term vibration, the outer diameter of the heads 12, 12 is formed larger than the inner diameter of the bolt insertion holes 9b, 9b, so that the mass member 6 can be prevented from falling off from the outer metal fitting 9.

[0050] Furthermore, since the heads 12, 12 of each fastening bolt 7, 7 are accommodated within the respective recesses 9a, 9a of the outer fitting 3, they do not protrude beyond the outer surfaces of both side walls 9, 9 of the outer fitting 3, thereby making it possible to reduce the size of the entire dynamic damper 1.

[0051] Furthermore, since the bolt insertion holes 9b are formed to be sufficiently larger than the outer diameter of the large diameter portions 13a, interference with the outer circumferential surfaces of the large diameter portions 13a during vibration can be suppressed, and therefore a decrease in the vibration suppression effect of the mass member 6 and the elastic bodies 5 can be prevented.

[0052] Furthermore, because the center of elasticity of each elastic body 5 coincides with the center of gravity P of the mass member 6 with respect to the translational vibration in the vertical direction (arrow X direction), width direction (arrow Y direction), and longitudinal direction (arrow Z direction), the mass member 6 does not rotate and is therefore not affected by natural vibration in the rotational direction. This increases the vibration damping effect of the dynamic damper 1.

[0053] As described above, when the mass member 6 is fixed to the inner metal fitting 4 by the fastening bolts 7, 7, the shafts 13, 13 of the fastening bolts 7, 7 are inserted into the bolt insertion holes 9b, 9b of the outer metal fitting 3 and the insertion holes 11a, 11a of the inner metal fitting 4 while the male threaded portions 13b, 13b are screwed into the female threaded holes 6a, 6a of the mass member 6, and the end faces 13c, 13c of the large diameter portions 13a, 13a come into contact (seat) with the hole edges of the insertion holes 11a, 11a, restricting further screwing. This prevents the fastening bolts 7, 7 from being screwed excessively into the female threaded holes 6a, 6a. Therefore, the outward protrusions of both heads 12, 12 are the same, and a good weight balance can be achieved in the mass member 6. In other words, the heads 12 of both fastening bolts 7, 7 are substantially the same and do not protrude outward beyond the heads 12 of the other, so that the weight balance of the mass member 6 can be achieved.

[0054] Furthermore, because the heads 12, 12 of the fastening bolts 7, 7 are formed in a flat disk shape, they can be easily accommodated within the recesses 9a, 9a of the outer metal fitting 3, and since they do not protrude to the outside from within the recesses 9a, 9a, the dynamic damper can be further reduced in size.

[0055] The present invention is not limited to the configurations of the above-described embodiments. For example, the shapes of the outer metal fitting 3 and the inner metal fitting 4 and the shape of the mass member 6 can be further modified.

[0056] In addition, in this embodiment, the pair of female screw holes 6a, 6a of the mass member 6 are provided coaxially, but it is also possible to provide them offset from each other in the front-rear or up-down direction.

[0057] In addition, the dynamic damper can also be applied to other vibrating members of a vehicle body or to vibrating members of ships and the like other than automobiles. [Explanation of symbols]

[0058] 01...Front suspension member 02...Frame 1. Dynamic damper 2…Mounting bracket 3...Outer metal fittings (outer member) 4…Inner metal fitting (inner component) 5...Elastic body 6…Mass member 7... Fastening bolt (connecting member) 8…Bottom wall 9…Both side walls 9a…Recess 9b...Bolt insertion hole (insertion hole) 10...bottom 11...Both sides 11a…insertion hole 12...Head 13...Shaft 13a…Large diameter section 13b…Male thread 13c...end face P: Center of gravity of mass member

Claims

1. the vibration source is attached to an outer member having a pair of left and right side walls, an inner member is disposed inside the outer member and has two side pieces facing the both side walls, a plurality of elastic bodies vulcanized and bonded between the inner surfaces of the both side walls of the outer member and the outer surfaces of the both side pieces of the inner member, a mass member disposed inside the inner member, and a pair of connecting members for fixing the mass member to the inner member, the outer member has insertion holes formed through both side walls thereof, and through which the connecting members are inserted; the inner member has insertion holes formed through both side pieces thereof, and through which the shafts of the connecting members are inserted; and a pair of fixing holes formed on both sides of the mass member, and into which the tips of the shafts of the connecting members inserted through the insertion holes are fixed; the mass member is connected and fixed to the inner member by the connecting members inserted through the insertion holes of the outer member; The elastic bodies are disposed on both side walls of the outer member and at four corners of both side pieces of the inner member, each of the insertion holes on both side walls of the outer member is formed at a position avoiding the elastic body, and a recess is formed around each of the insertion holes, recessed toward the inner member; A dynamic damper, characterized in that, when the tip end of the connecting member is fixed in the fixing hole of the mass member, the head of the connecting member is disposed inside the recess.

2. 2. The dynamic damper according to claim 1, When the dynamic damper is applied to a vibration source of a vehicle body, A dynamic damper characterized in that the center of elasticity of the elastic body in each vibration direction from the vibration source to the dynamic damper in the vertical direction, width direction, and longitudinal direction of the vehicle body is aligned with or nearly aligned with the center of gravity of the mass member.

3. 2. The dynamic damper according to claim 1, The fixing holes formed on both sides of the mass member are female threaded holes, The connecting member has a head and a shaft portion integrally provided with the head, a male screw portion is formed at a tip end of the shaft portion, the male screw portion being screwed into each of the female screw holes at both sides of the mass member, A dynamic damper characterized in that the shaft portion has a large diameter portion on the head side having an outer diameter larger than the inner diameter of each insertion hole of the inner member, and when the male threaded portion is screwed into the female threaded hole, the end face of the large diameter portion on the male threaded portion side abuts against the hole edge of each insertion hole, regulating the maximum screwing amount.

4. 2. The dynamic damper according to claim 1, A dynamic damper characterized in that the head of the connecting member is formed in a flat disk shape and has a hexagonal groove for a screwing tool formed in the central position of its outer surface.

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