Dynamic damper

Abstract

To provide a dynamic damper capable of improving the yield of a fall-off prevention plate.SOLUTION: In a dynamic damper 20 in which an inner peripheral surface of a shaft-shaped member 21 and an outer peripheral surface of a cylindrical mass body 25 are connected by a vibration control substrate 26, a fall-off prevention plate 30 is attached to the shaft-shaped member 21. When viewed in an axial direction, an outer shape of body parts 32, 33 of the fall-off plate 30 is polygonal. As a result, when forming the plurality of fall-off prevention plates 30 from a flat plate material P, the yield of the fall-off prevention plates 30 can be improved compared to when the outer shape of the body parts 32, 33 is circular with a mounting part 31 as a center.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a dynamic damper equipped with a fall-off prevention plate for preventing a mass body from falling off, and more particularly to a dynamic damper that can improve the yield of fall-off prevention plates. [Background technology]

[0002] In vehicles such as automobiles and industrial machines, there are many harmful vibrations such as engine vibrations and resonance that occurs during driving (operation), so dynamic dampers are sometimes built in to suppress these harmful vibrations. Some dynamic dampers are equipped with a cylindrical shaft-like member attached to the mating member whose vibration is to be suppressed, a cylindrical mass body that coaxially surrounds the shaft-like member, and an elastic vibration-isolating base that connects the outer circumferential surface of the shaft-like member and the inner circumferential surface of the mass body.

[0003] In Patent Document 1, in order to prevent a mass body from falling off from a shaft-shaped member attached to a mating member due to damage to the vibration-proof base, a circular anti-fall-off plate with an outer diameter larger than the inner diameter of the mass body is attached to the end of the shaft-shaped member opposite the mating member. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2000-337431 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, when forming multiple disc-shaped anti-fall-out plates in the above-mentioned conventional technology by cutting them out from a flat plate material, it is difficult to ensure the yield, which is the ratio of the finished weight of the anti-fall-out plates to the input weight of the plate material.

[0006] The present invention has been made to solve the above-mentioned problems, and has an object to provide a dynamic damper that can improve the yield of anti-fall-off plates. [Means for solving the problem]

[0007] To achieve this objective, the dynamic damper of the present invention comprises an axial member having a first and second axial end, the second end being attached to a mating member, a cylindrical mass body surrounding the axial member, a vibration-damping base made of an elastic material connecting the inner surface of the axial member and the outer surface of the mass body, and an anti-slip plate attached to the first end of the axial member, the anti-slip plate comprising an attachment portion attached and superimposed on the first end, and a main body portion extending from the attachment portion in at least one direction perpendicular to the axis of the axial member, and the outer shape of the main body portion when viewed in the axial direction is polygonal. Effect of the Invention

[0008] According to the dynamic damper described in claim 1, the outer shape of the main body of the fall-off prevention plate as viewed from the axial direction (as viewed in the axial direction) is polygonal. This makes it possible to reduce waste from the plate material when forming multiple fall-off prevention plates from a flat plate material by bringing the sides of each main body close to each other or making them approximately coincident. As a result, the yield of fall-off prevention plates can be improved by having the outer shape of the main body be polygonal compared to when it is circular with the mounting part at the center.

[0009] The dynamic damper according to claim 2 achieves the following effect in addition to the effect achieved by the dynamic damper according to claim 1. When viewed in the axial direction, the outer shape of the fall-off prevention plate, including the mounting portion and the main body portion, is polygonal. This makes it possible to reduce waste from the plate material by bringing the edges of each fall-off prevention plate close to each other or roughly matching them when forming multiple fall-off prevention plates from a flat plate material. This makes it possible to further improve the yield of fall-off prevention plates.

[0010] The dynamic damper according to claim 3 achieves the following effect in addition to the effect achieved by the dynamic damper according to claim 2. The outer shape of the fall-off prevention plate when viewed in the axial direction is rectangular (including square). This makes it easier to make the sides of each fall-off prevention plate approximately coincident with each other when forming multiple fall-off prevention plates from a flat plate material, further reducing the amount of waste from the plate material. This further improves the yield of fall-off prevention plates.

[0011] The dynamic damper according to claim 4 has the following effects in addition to those of the dynamic damper according to claim 3. The outer shape of the fall-off prevention plate when viewed in the axial direction is a rectangle with two perpendicular sides of different lengths. The length of the long side of this rectangle can prevent the mass body from falling off when the vibration-isolating base is damaged. Furthermore, by rotating the main body around the mounting part, interference between the items around the dynamic damper and the fall-off prevention plate can be easily avoided.

[0012] The dynamic damper according to claim 5 achieves the following effects in addition to those achieved by the dynamic damper according to claim 4. The main body is provided on both sides of the mounting part in the axis-perpendicular direction. The dimension from the outer circumferential surface of the shaft-shaped member to the tip of the main body in the axis-perpendicular direction is equal to or greater than the difference between the maximum value of the inner diameter of the mass body and the minimum value of the outer diameter of the shaft-shaped member. As a result, even if the outer circumferential surface of the shaft-shaped member and the inner circumferential surface of the mass body come into contact with each other in the circumferential direction when the vibration-isolating base is damaged, parts of the mass body and the main body overlap when viewed in the axial direction. Therefore, even if the anti-drop-off plate is rectangular, the reliability of preventing the mass body from falling off when the vibration-isolating base is damaged can be improved.

[0013] The dynamic damper of claim 6 achieves the following effects in addition to those of the dynamic damper of claim 5. The main body is provided only on one side of the mounting part in the direction perpendicular to the axis, making it possible to reduce the weight of the fall-off prevention plate. Furthermore, the main body is located on the upper half of the circumference around the mounting part. When the vibration-isolating base is damaged, the mass body is likely to be displaced downward relative to the shaft-shaped member due to gravity, so the mass body is likely to get caught on the main body provided on the upper half of the circumference. This ensures time for the mass body to fall over the main body. The contact sound between the mass body and the main body or shaft-shaped member that occurs before the mass falls off can encourage replacement of the dynamic damper.

[0014] The dynamic damper according to claim 7 achieves the following effect in addition to the effect achieved by the dynamic damper according to any one of claims 1 to 6. The anti-fall-off plate has a hook portion bent from the tip of the main body in the axis-perpendicular direction toward the mass body. When the vibration-isolating base is damaged, the mass body may strike the anti-fall-off plate, causing the main body to bend in the axial direction with the vicinity of the mounting portion as a fulcrum. In this case, the hook portion faces outward in the axis-perpendicular direction and toward the mass body, so that the vibration-isolating base that remains attached to the mass body, or the mass body itself, is likely to be caught by the hook portion. This hooking makes it difficult for the mass body to fall off the shaft-shaped member even if the main body is bent. [Brief description of the drawings]

[0015] [Figure 1] FIG. 2 is a perspective view of a vibration isolation unit to which a dynamic damper is attached in the first embodiment. [Diagram 2] FIG. 2A is a cross-sectional view of a dynamic damper, and FIG. 2B is a schematic cross-sectional view of the dynamic damper when the vibration-isolating base is broken. [Diagram 3] 2 is a perspective view of the dynamic damper and the anti-vibration unit with the fall-off prevention plate rotated relative to FIG. 1. FIG. [Figure 4] 5A to 5C are schematic diagrams showing a method for manufacturing the fall-off prevention plate. [Diagram 5]FIG. 13(a) is a cross-sectional view of a dynamic damper according to a second embodiment, and FIG. 13(b) is a perspective view of a dynamic damper according to a third embodiment. [Figure 6] FIG. 13(a) is a cross-sectional view of a dynamic damper in a fourth embodiment, and (b) is a schematic cross-sectional view of the dynamic damper when the vibration-isolating base is broken. [Figure 7] FIG. 1A is a schematic diagram showing a method for manufacturing a fall-off prevention plate, and FIG. 1B and FIG. 1C are schematic diagrams showing modified examples of the fall-off prevention plate. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, preferred embodiments will be described with reference to the accompanying drawings. Fig. 1 is a perspective view of an anti-vibration unit 10 to which a dynamic damper 20 according to a first embodiment is attached. The anti-vibration unit 10 is an engine mount that is installed in a vehicle such as an automobile to reduce vibrations transmitted from the engine to the vehicle body.

[0017] The vibration isolation unit 10 includes a cylindrical first member 11 attached to the engine side, a cylindrical second member 12 attached to the vehicle body side, and a connecting member (not shown) made of an elastic body such as rubber or elastomer that connects the first member 11 and the second member 12. The second member 12 surrounds the first member 11 and is fixed to the vehicle body by three legs 13 extending downward. A dynamic damper 20 is attached to the vibration isolation unit 10 (counterpart member) via a bracket 14 (see FIG. 2(a)) that spans two of the three legs 13.

[0018] The dynamic damper 20 will be described with reference to Fig. 2(a) in addition to Fig. 1. Fig. 2(a) is a cross-sectional view of the dynamic damper 20. Note that the cross-sectional view of Fig. 2(a) is a cross-sectional view along the up-down direction, including the axis C of the shaft-shaped member 21 of the dynamic damper 20. Note that in this specification, the direction of this axis C will be simply referred to as the axial direction, and the direction perpendicular to the axis C will be referred to as the axial-perpendicular direction.

[0019] The dynamic damper 20 is a device for suppressing harmful vibrations such as vibrations of an engine or resonance that occurs during driving (operation). The dynamic damper 20 includes a shaft-shaped member 21, a cylindrical mass body 25 that surrounds the shaft-shaped member 21, a vibration-isolating base 26 that connects the shaft-shaped member 21 and the mass body 25, and a drop-off prevention plate 30 that is attached to the shaft-shaped member 21.

[0020] The shaft-shaped member 21 is a cylindrical metal member centered on the axis C, and has an outer diameter R2 that is approximately uniform in the circumferential direction. The shaft-shaped member 21 has a first end 22 and a second end 23 in the axial direction. The shaft portion of a bolt 24 inserted from the first end 22 protrudes from the second end 23, and the protruding portion is attached to the bracket 14 of the vibration-proof unit 10. In this way, the second end 23 of the shaft-shaped member 21 is attached to the bracket 14.

[0021] The mass body 25 is a cylindrical metallic member centered on the axis C, and is formed with a large wall thickness. The inner diameter R1 of the mass body 25 is approximately uniform in the circumferential direction. The mass body 25 is disposed coaxially with the outer circumferential surface of the shaft-shaped member 21 at a predetermined interval. The shaft-shaped member 21 protrudes from the mass body 25 on both sides in the axial direction.

[0022] The vibration-isolating base 26 is a cylindrical member made of an elastic body such as rubber or a thermoplastic elastomer. The inner peripheral surface of the vibration-isolating base 26 is vulcanization-bonded to the outer peripheral surface of the shaft-shaped member 21, and the outer peripheral surface of the vibration-isolating base 26 is vulcanization-bonded to the inner peripheral surface of the mass body 25. In this way, the vibration-isolating base 26 connects the outer peripheral surface of the shaft-shaped member 21 and the inner peripheral surface of the mass body 25 around the entire circumference.

[0023] The anti-fall-off plate 30 is intended to prevent the mass body 25 from falling off from the shaft-shaped member 21 in the event of damage to the vibration-isolating base 26. Note that in this specification, preventing falling off is not limited to completely preventing the mass body 25 from falling off from the shaft-shaped member 21, but also includes making it difficult for the mass body 25 to fall off from the shaft-shaped member 21.

[0024] The fall-off prevention plate 30 is formed in a flat plate shape and includes an attachment portion 31 and a pair of main body portions 32, 33. The attachment portion 31 is a portion that is sandwiched between the first end 22 of the shaft-shaped member 21 and the head of the bolt 24, and is attached to the first end 22 by overlapping it. A through hole is formed in the center of the attachment portion 31, into which the shaft portion of the bolt 24 is inserted.

[0025] The main body portion 32 is a portion that extends upward from the mounting portion 31 in the direction perpendicular to the axis. The main body portion 33 is a portion that extends downward from the mounting portion 31 in the direction perpendicular to the axis. The main body portions 32, 33 are integrally molded with the mounting portion 31. The external shape of each of the main body portions 32, 33 is a rectangle with two perpendicular sides of different lengths when viewed in the axial direction.

[0026] Furthermore, the outer shape of the fall-off prevention plate 30 including the mounting portion 31 and the main body portions 32 and 33 is a rectangle with two perpendicular sides of different lengths when viewed in the axial direction. A long side 30a of this rectangle is formed along the vertical direction, and a short side 30b, which is shorter than the long side 30a, is formed along the horizontal direction.

[0027] Next, the function of the drop-off prevention plate 30 will be described with further reference to Fig. 2(b). Fig. 2(b) is a schematic cross-sectional view of the dynamic damper 20 when the vibration-isolating base 26 is damaged. Fig. 2(b) illustrates an example of damage to the vibration-isolating base 26 in which both the adhesive surface between the shaft-shaped member 21 and the vibration-isolating base 26 and the adhesive surface between the mass body 25 and the vibration-isolating base 26 peel off, causing the vibration-isolating base 26 to fall off.

[0028] 2(b), the function of the drop-off prevention plate 30 will be described below, but it also functions in other cases of damage. Other cases of damage include when the adhesive surface between either the shaft-shaped member 21 or the mass body 25 and the vibration-isolating base 26 peels off, or when the vibration-isolating base 26 is separated (broken) in the direction perpendicular to the axis.

[0029] When the vibration-isolating base 26 is damaged, the connection between the shaft-shaped member 21, which is fixed to the vehicle via the bracket 14 and the vibration-isolating unit 10, and the mass body 25 is released. At this time, because the vibration-isolating unit 10, which is sufficiently larger than the inner diameter of the mass body 25, is attached to the second end 23 of the shaft-shaped member 21, the mass body 25 does not essentially fall off from the second end 23 side.

[0030] On the other hand, there is a risk that the mass body 25 may fall off from the first end 22 of the shaft-shaped member 21. However, in this embodiment, a fall-prevention plate 30 that protrudes from the shaft-shaped member 21 in the axis-perpendicular direction is attached to the first end 22, so it is possible to prevent the mass body 25 from going over the fall-prevention plate 30 and falling off. This fall-prevention plate 30 has main body portions 32, 33 on both sides of the mounting portion 31 in the axis-perpendicular direction, so that the mass body 25 is less likely to go over the fall-prevention plate 30, making it even more difficult for the mass body 25 to fall off.

[0031] Here, when the drop-out prevention plate 30 having the main body portions 32, 33 on both sides is rectangular, there is a risk that the mass body 25 will exceed the drop-out prevention plate 30 and fall off, depending on the relationship of each dimension. For example, if the dimension L from the outer circumferential surface of the shaft-shaped member 21 to the tip (short side 30b) of the main body portions 32, 33 in the axis-perpendicular direction is less than the difference (R1-R2) between the inner diameter R1 of the mass body 25 and the outer diameter R2 of the shaft-shaped member 21, there is a risk that the mass body 25 will exceed the drop-out prevention plate 30, depending on the length of the short side 30b.

[0032] In contrast, in this embodiment, because dimension L is equal to or greater than the difference (R1-R2), even if circumferential portions of the outer circumferential surface of shaft-shaped member 21 and the inner circumferential surface of mass body 25 come into contact with each other when vibration-isolating base 26 is damaged as shown in Fig. 2(b), portions of mass body 25 and main bodies 32, 33 will overlap when viewed in the axial direction. As a result, since mass body 25 basically does not exceed drop-out prevention plate 30, even if drop-out prevention plate 30 is rectangular, it is possible to improve the reliability of preventing mass body 25 from falling off when vibration-isolating base 26 is damaged.

[0033] Fig. 3 is a perspective view of the dynamic damper 20 and the anti-vibration unit 10 with the anti-fall-off plate 30 rotated with respect to Fig. 1. Fig. 3 shows a case where an article 15 mounted on a vehicle together with the anti-vibration unit 10 is placed close to and below the shaft-shaped member 21. In this case, if the anti-fall-off plate 30 is circular or square when viewed in the axial direction, the anti-fall-off plate 30 may interfere with the article 15, making it impossible to attach the anti-fall-off plate 30 to the shaft-shaped member 21. Furthermore, if the anti-fall-off plate 30 is made small, such as circular, in order to avoid this interference, it may not be possible to sufficiently prevent the mass body 25 from falling off.

[0034] In contrast, the fall-off prevention plate 30 of this embodiment is rectangular with long sides 30a and short sides 30b. Therefore, as described above, the length of the long sides 30a can prevent the mass body 25 from falling off when the vibration-isolating base 26 is damaged. Furthermore, by rotating the main body 32 around the mounting part 31 from the state shown in Fig. 1 to the state shown in Fig. 3, interference between the article 15 and the fall-off prevention plate 30 can be easily avoided.

[0035] 4 is a schematic diagram showing a manufacturing method of the fall-off prevention plate 30. A plurality of fall-off prevention plates 30 are manufactured by cutting out from a flat plate-shaped plate material P. Since each of the fall-off prevention plates 30 is rectangular, for example, by forming the long sides 30a to approximately coincide with each other and the short sides 30b to approximately coincide with the edge of the plate material P, the waste portion of the plate material P can be reduced. Therefore, the yield rate, which is the ratio of the product weight of the fall-off prevention plates 30 to the input weight of the plate material P, can be improved.

[0036] In addition, depending on the size of the plate material P, the layout when forming multiple fall-off prevention plates 30 from the plate material P may be such that the short sides 30b are approximately aligned with each other, or the long sides 30a are approximately aligned with each other and the short sides 30b are approximately aligned with each other. The multiple short sides 30b may be approximately aligned with the long sides 30a. In addition, "approximately aligned" does not necessarily mean that the long sides 30a and the short sides 30b are completely aligned, and there may be a slight gap between them.

[0037] Next, a second embodiment will be described with reference to Fig. 5(a). In the first embodiment, a fall-off prevention plate 30 in which main body parts 32, 33 are provided on both sides of the mounting part 31 in the direction perpendicular to the axis is described. In contrast, in the second embodiment, a fall-off prevention plate 41 in which a main body part 32 is provided only on one side of the mounting part 31 in the direction perpendicular to the axis is described. Note that the same parts as in the first embodiment are given the same reference numerals and the following description will be omitted.

[0038] Fig. 5(a) is a cross-sectional view of a dynamic damper 40 according to the second embodiment. The cross-sectional view of Fig. 5(a) is a cross-sectional view along the up-down direction and includes the axis C. The dynamic damper 40 includes a shaft-shaped member 21, a mass body 25, a vibration-isolating base 26, and a drop-off prevention plate 41.

[0039] The fall-off prevention plate 41 is obtained by omitting the main body portion 33 extending downward from the mounting portion 31 compared to the fall-off prevention plate 30 in the first embodiment, and is otherwise configured the same as the fall-off prevention plate 30. That is, the fall-off prevention plate 41 includes the mounting portion 31 and the main body portion 32 extending upward from the mounting portion 31. In this way, since the main body portion 32 is provided only on one side of the mounting portion 31 in the direction perpendicular to the axis, the fall-off prevention plate 41 can be made lighter.

[0040] When the vibration-isolating base 26 is damaged, the mass body 25 is likely to be displaced downward relative to the shaft-shaped member 21 due to gravity, and the mass body 25 is likely to get caught on the main body portion 32 extending upward from the mounting portion 31. This ensures time for the mass body 25 to pass over the main body portion 32 and fall off. The contact noise between the mass body 25 and the main body portion 32 or the shaft-shaped member 21 that occurs before the mass body 25 falls off can be heard to urge the driver of the vehicle to replace the dynamic damper 40.

[0041] Furthermore, the main body portion 32 need not necessarily extend vertically upward from the mounting portion 31, but may be located in the upper half of the circumference of the mounting portion 31. In this case as well, the mass body 25 can be easily caught by the main body portion 32, and the time until the mass body 25 falls off can be secured.

[0042] However, it is preferable that main body 32 extends vertically upward from attachment portion 31. In this case, for mass body 25 to fall off, mass body 25 needs to be displaced upward by a larger amount than in any other direction than vertically upward, making it difficult for mass body 25 to fall off.

[0043] Next, a third embodiment will be described with reference to Fig. 5(b). In the first embodiment, the entire outer shape of the fall-off prevention plate 30 is rectangular. In contrast, in the third embodiment, the outer shape of a portion of the fall-off prevention plate 51 is rectangular. Note that the same parts as in the first embodiment are given the same reference numerals and the following description will be omitted.

[0044] Fig. 5(b) is a perspective view of the dynamic damper 50 in the third embodiment. The cross-sectional view of the dynamic damper 50 is substantially the same as Fig. 2(a). The dynamic damper 50 includes a shaft-shaped member 21, a mass body 25, a vibration-isolating base 26, and a drop-off prevention plate 51.

[0045] The fall-off prevention plate 51 is formed in a flat plate shape and includes an attachment portion 52 and a pair of main body portions 53, 54. The attachment portion 52 is a portion that is sandwiched between the first end 22 of the shaft-shaped member 21 and the head of the bolt 24, and is attached by overlapping the first end 22. The attachment portion 52 is in the shape of an annular plate with a through hole formed in the center, into which the shaft portion of the bolt 24 is inserted.

[0046] The main bodies 53 and 54 are rectangular in shape with the short sides 30b shorter than those of the main bodies 32 and 33 in the first embodiment, but otherwise have the same configuration as the main bodies 32 and 33. The short sides 30b of the main bodies 53 and 54 are smaller than the outer diameter of the attachment portion 52. This allows the weight of the fall-off prevention plate 51 to be reduced compared to the fall-off prevention plate 30 in the first embodiment.

[0047] Even when multiple fall-off prevention plates 51 are formed from a flat plate material P, the edges of the main body parts 53, 54 can be brought close to each other or made to coincide with each other to reduce waste from the plate material P. Therefore, the yield of fall-off prevention plates 51 can be improved by having the main body parts 53, 54 have a rectangular outer shape compared to a circular shape with the mounting part 52 at the center.

[0048] Next, a fourth embodiment will be described with reference to Fig. 6(a) to Fig. 7(a). In the fourth embodiment, a case where hook portions 62, 63 are provided on a fall prevention plate 61 in contrast to the first embodiment will be described. Note that the same parts as those in the first embodiment are given the same reference numerals and the following description will be omitted.

[0049] Fig. 6(a) is a cross-sectional view of the dynamic damper 60 in the fourth embodiment. Fig. 6(b) is a schematic cross-sectional view of the dynamic damper 60 when the vibration-isolating base 26 is damaged. The cross-sectional views of Fig. 6(a) and Fig. 6(b) are cross-sectional views along the up-down direction including the axis C.

[0050] 6(a), the dynamic damper 60 includes a shaft-shaped member 21, a mass body 25, an anti-vibration base 26, and a drop-off prevention plate 61. The drop-off prevention plate 61 is obtained by adding hook portions 62, 63 to the drop-off prevention plate 30 (the mounting portion 31 and the main body portions 32, 33) in the first embodiment.

[0051] The hook portion 62 is a portion bent substantially perpendicularly from the tip (upper short side 30b) of the main body 32 in the axis-perpendicular direction toward the mass body 25. The hook portion 63 is a portion bent substantially perpendicularly from the tip (lower short side 30b) of the main body 33 in the axis-perpendicular direction toward the mass body 25. The attachment portion 31, the main bodies 32 and 33, and the hook portions 62 and 63 are integrally molded.

[0052] 6(b), when the vibration-isolating base 26 is damaged, the mass body 25 hits the anti-drop-off plate 61, and the main body portions 32, 33 may bend in the axial direction with the vicinity of the mounting portion 31 as a fulcrum. This bending may cause the mass body 25 to easily go over the anti-drop-off plate 61 and fall off.

[0053] However, in this embodiment, when main body portions 32, 33 are bent as described above, tips 64 of hook portions 62, 63 face outward in the axis-perpendicular direction and toward mass body 25. As a result, when mass body 25 attempts to pass over anti-drop plate 61, a part of vibration-isolating base 26 that remains attached to mass body 25, or mass body 25 itself, is more likely to get caught on tips 64 of hook portions 62, 63. This catch makes it difficult for mass body 25 to fall off shaft-shaped member 21 even if main body portions 32, 33 are bent.

[0054] 7(a) is a schematic diagram showing a manufacturing method of the drop-out prevention plate 61. A plurality of drop-out prevention plates 61 are manufactured by cutting out from a flat plate material P. Specifically, first, a plurality of intermediate materials are cut out from the plate material P in a layout in which the long sides 30a of the drop-out prevention plates 61 coincide with each other, and the portions that become the tips 64 of the hook parts 62, 63 coincide with each other. Then, in each of the intermediate materials, the hook parts 62, 63 are bent relative to the main parts 32, 33 to form the short sides 30b, thereby forming the drop-out prevention plate 61. In this case as well, the yield of the drop-out prevention plates 61 can be improved, as in the first embodiment.

[0055] The tip 64 is formed in a sawtooth shape. This makes it easier for the tip 64 to catch on a part of the vibration-isolating base 26 that remains attached to the mass body 25 when the mass body 25 attempts to pass over the curved main body portions 32, 33 as shown in Figure 6(b). As a result, it becomes more difficult for the mass body 25 to fall off the shaft-shaped member 21.

[0056] Furthermore, since the multiple fall-off prevention plates 61 are cut out from the plate material P in a layout in which the sawtooth tips 64 are aligned with each other, post-processing for forming the tips 64 from the straight portions is not required. In addition, the waste generated when forming the tips 64 from the straight portions can be reduced, and the yield of the fall-off prevention plates 61 can be improved.

[0057] The present invention has been described above based on the embodiments, but the present invention is not limited to the above embodiments, and it can be easily imagined that various improvements and modifications are possible within the scope of the present invention. For example, the mating member to which the dynamic dampers 20, 40, 50, 60 are attached is not limited to the vibration isolation unit 10 of the vehicle. Other mating members include vibration isolation devices other than the vibration isolation unit 10 (engine mount), and predetermined parts of the vehicle body. In addition, the mating member is not limited to a part of the vehicle, and may be a part of industrial machinery, etc.

[0058] In the above embodiment, the shaft-shaped member 21 and the mass body 25 are cylindrical, but this is not necessarily limited to this. For example, the shaft-shaped member 21 may be rectangular or columnar. When the shaft-shaped member 21 is columnar, the counter member or the drop-out prevention plate 30, 41, 51, 61 may be attached to the first end 22 or the second end 23 by screws, rivets, adhesive, welding, or the like.

[0059] The outer peripheral surface of shaft-shaped member 21, the inner peripheral surface of mass body 25, and the outer peripheral surface of mass body 25 are not limited to a substantially perfect circle in a cross section perpendicular to axis C, and may be an ellipse or a polygon. If the inner diameter of mass body 25 and the outer diameter of shaft-shaped member 21 are thereby non-uniform in the circumferential direction, the maximum value of the inner diameter of mass body 25 is taken as R1, and the minimum value of the outer diameter of shaft-shaped member 21 is taken as R2. If dimension L described in the first embodiment is equal to or greater than the difference (R1-R2) between these values, it is possible to improve the reliability of preventing mass body 25 from falling off when vibration-proof base 26 is damaged.

[0060] Also, the dimension L may be less than the difference (R1-R2). Even in this case, as described in the second embodiment, it is possible to ensure the time until the mass body 25 exceeds the main bodies 32 and 33 and falls off, and it is possible to prompt the replacement of the dynamic damper 20.

[0061] In the above embodiment, the vibration-isolating base 26 is cylindrical, but this is not necessarily limited to this. The shape of the vibration-isolating base 26 may be changed as appropriate depending on the shape of the outer circumferential surface of the shaft-shaped member 21 and the inner circumferential surface of the mass body 25. Furthermore, the vibration-isolating base 26 is not limited to connecting the shaft-shaped member 21 and the mass body 25 over the entire circumference, and may connect only parts of them in the circumferential direction.

[0062] In the above-mentioned first, second and fourth embodiments, the outer shape of the fall-off prevention plate 30, 41, 61 as viewed in the axial direction is a rectangle with two perpendicular sides of different lengths, but this is not necessarily limited to this. Modified examples of the outer shape of the fall-off prevention plate are shown in Fig. 7(b) and Fig. 7(c).

[0063] The fall-prevention plate 70 in FIG. 7(b) has a square (a type of rectangular) outer shape when viewed in the axial direction (when viewed in the plate thickness direction). The vicinity of the central through-hole of the fall-prevention plate 70 corresponds to the mounting portion, and the portion extending radially from the mounting portion in the axially perpendicular direction corresponds to the main body. When forming a plurality of fall-prevention plates 70 from a flat plate material P, as in the first embodiment, the edges of each fall-prevention plate 70 are made to substantially coincide with each other, thereby reducing the amount of waste from the plate material P. This improves the yield of the fall-prevention plates 70.

[0064] The fall-prevention plate 80 in Fig. 7(c) has an outer shape of an equilateral triangle when viewed in the axial direction (when viewed in the plate thickness direction). In the fall-prevention plate 80, the vicinity of the central through-hole corresponds to the mounting portion, and the portion extending radially from the mounting portion in the direction perpendicular to the axis corresponds to the main body. When forming a plurality of fall-prevention plates 80 from a flat plate material P, similar to the first embodiment, the edges of each fall-prevention plate 80 are made to substantially coincide with each other, thereby reducing the amount of waste from the plate material P. This improves the yield of the fall-prevention plates 80.

[0065] Furthermore, the outer shape of the fall-prevention plate as viewed in the axial direction may be a polygonal shape other than a rectangular shape or an equilateral triangle shape. In any shape, it is easier to bring the sides of each fall-prevention plate close to each other or to roughly coincide with each other when forming multiple fall-prevention plates from a flat plate material P, compared to when the outer shape of the fall-prevention plate is circular. As a result, the yield of the fall-prevention plates can be improved.

[0066] Furthermore, the overall outer shape of the fall-prevention plate need not necessarily be polygonal, as long as the main body parts 53, 54 provided around the mounting part 52 are polygonal, as in the third embodiment. If the main body parts 53, 54 are polygonal, it is easy to bring the sides of the main body parts 53, 54 close to each other or approximately coincide with each other when forming a plurality of fall-prevention plates from a flat plate material P. As a result, the yield of the fall-prevention plates can be improved.

[0067] The number of the main bodies 53, 54 is not limited to two, but may be three or more, or may be one as in the second embodiment. However, it is preferable that the number of the main bodies 53, 54 is two or less, since this makes it easier to compact the layout when forming a plurality of fall-off prevention plates from the plate material P.

[0068] In the above fourth embodiment, the tip 64 of the hook portion 62, 63 is described as being sawtooth-shaped, but this is not necessarily limited to this. For example, the tip 64 may be linear or curved. Also, the hook portion 62, 63 may be provided on the fall-off prevention plate 41, 51 in the second and third embodiments. [Explanation of symbols]

[0069] 10 Anti-vibration unit (counterpart) 14 Bracket (part of the mating component) 20,40,50,60 Dynamic Damper 21 Shaft-shaped member 22 1st end 23 2nd end 25 mass body 26 Anti-vibration base 30,41,51,61,70,80 Anti-fall plate 31,52 Mounting part 32, 33, 53, 54 Main body 62,63 Hook section

Claims

1. a shaft-shaped member having a first end and a second end in an axial direction, the second end being attached to a mating member; A cylindrical mass body surrounding the shaft-shaped member; an elastic vibration-isolating base that connects an inner peripheral surface of the shaft member and an outer peripheral surface of the mass body; a drop-out prevention plate attached to the first end of the shaft-shaped member, The fall-off prevention plate has an attachment portion attached to the first end in a superimposed manner; a main body portion extending from the attachment portion in at least one direction perpendicular to the axis of the shaft-shaped member, A dynamic damper characterized in that the outer shape of the main body when viewed in the axial direction is polygonal.

2. 2. The dynamic damper according to claim 1, wherein the outer shape of the fall-off prevention plate when viewed in the axial direction is polygonal.

3. 3. The dynamic damper according to claim 2, wherein an outer shape of the fall-off prevention plate when viewed in the axial direction is rectangular.

4. 4. The dynamic damper according to claim 3, wherein the outer shape of the fall-off prevention plate as viewed in the axial direction is a rectangle having two perpendicular sides of different lengths.

5. The main body portion is provided on both sides of the attachment portion in a direction perpendicular to the axis, 5. A dynamic damper as claimed in claim 4, characterized in that the dimension from the outer peripheral surface of the shaft-shaped member to the tip of the main body in the axis-perpendicular direction is greater than or equal to the difference between the maximum value of the inner diameter of the mass body and the minimum value of the outer diameter of the shaft-shaped member.

6. 2. The dynamic damper according to claim 1, wherein the main body portion is provided on only one side of the mounting portion in the direction perpendicular to the axis, and is positioned around an upper half of the mounting portion.

7. 7. The dynamic damper according to claim 1, wherein the anti-fall-off plate has a hook portion bent from a tip of the main body portion in the axis-perpendicular direction toward the mass body.

Images