Torsional damper

Abstract

To provide a torsional damper with a structure capable of reducing radiation noise from a hub with higher versatility.SOLUTION: A torsional damper 100 includes: a hub 10 fixed to a rotation shaft; a ring-shaped vibration ring 30 disposed along an outer periphery of the hub 10; and a ring-shaped elastomer 20 interposed between the vibration ring 30 and the hub 10. The vibration ring 30 includes: a ring-shaped body part 31; and a projection part 36 projecting from the body part 31. The vibration ring 30 includes the projection part 36 which makes the radial resonance frequency of the vibration ring 30 close to the radial resonance frequency of the hub 10.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a torsional damper. [Background technology]

[0002] A torsional damper (TVD) is a product that is attached to the tip of a crankshaft (rotating shaft) and has the function of absorbing vibrations that occur in the crankshaft. The torsional damper includes a hub, a vibration ring, and a ring-shaped elastic body interposed between the hub and the vibration ring. The vibration ring resonates in the rotational direction, so that the torsional damper suppresses (absorbs) vibrations in the torsional direction of the crankshaft. The rotational resonance frequency of the vibrating ring is often approximately 300 to 600 Hz. The vibrating ring also resonates in the axial direction. The axial resonance frequency of the vibrating ring is several hundred Hz, which is similar to the torsional vibration.

[0003] Incidentally, noise emitted from the hub is often problematic due to local axial resonance of the hub, and the frequency is high, at several thousand Hz.

[0004] Patent Document 1 describes a technique for forming a cavity in a hub (boss portion of the document) of a torsional damper (crank pulley of the document) in order to reduce the noise emitted from the hub. This technique utilizes the interference of sound waves. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2020-41684 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the technology of Patent Document 1, in order to reduce the noise radiated from the hub, it is necessary to create a cavity in the hub, and therefore it is necessary to set the volume and opening area of ​​the cavity according to the frequency of the radiated sound. For this reason, it is expected that this technology will not work depending on the size of the torsional damper, and it is a technology lacking in versatility.

[0007] The present invention has been made in consideration of the above problems, and provides a torsional damper having a structure capable of reducing noise radiated from a hub with greater versatility. [Means for solving the problem]

[0008] According to the present invention, there is provided a hub fixed to a rotating shaft; a ring-shaped vibration ring disposed along the outer periphery of the hub; a ring-shaped elastic body interposed between the vibration ring and the hub; A torsional damper comprising: The vibration ring has a ring-shaped main body and a protrusion protruding from the main body, The protrusions on the vibrating ring provide a torsional damper in which the radial resonant frequency of the vibrating ring approaches the axial resonant frequency of the hub. Effect of the Invention

[0009] According to the present invention, it is possible to reduce noise radiated from a hub with greater versatility. [Brief description of the drawings]

[0010] [Figure 1] FIG. 2 is a front view of the torsional damper according to the embodiment. [Diagram 2] FIG. 2 is a perspective cross-sectional view taken along line AA in FIG. [Diagram 3] FIG. 2 is a cross-sectional view taken along line AA in FIG. [Figure 4]1 is a schematic diagram showing a state in which a torsional damper according to an embodiment is attached to a crankshaft of an engine. [Diagram 5] 11A and 11B are diagrams illustrating the results of a natural vibration analysis of a vibration ring of the torsional damper according to the embodiment. [Figure 6] 11A and 11B are diagrams illustrating the results of a natural vibration analysis of a vibration ring of the torsional damper according to the embodiment. [Figure 7] 11A and 11B are diagrams illustrating the results of a natural vibration analysis of a vibration ring of the torsional damper according to the embodiment. [Figure 8] 11A and 11B are diagrams illustrating the results of a natural vibration analysis of a vibration ring of the torsional damper according to the embodiment. [Figure 9] 13A and 13B are diagrams showing the results of natural vibration analysis of a vibration ring of a torsional damper according to a comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In all the drawings, the same components are denoted by the same reference numerals, and the description thereof will be omitted as appropriate.

[0012] The torsional damper 100 of this embodiment comprises a hub 10 fixed to a rotating shaft (crankshaft 61 shown in Figure 4), a ring-shaped vibrating ring 30 arranged along the outer periphery of the hub 10, and a ring-shaped elastic body 20 interposed between the vibrating ring 30 and the hub 10. The vibration ring 30 has a ring-shaped main body 31 and a protrusion 36 protruding from the main body 31. Since the vibration ring 30 has the protrusion 36, the radial resonance frequency of the vibration ring 30 approaches the axial resonance frequency of the hub 10. Here, the fact that the radial resonant frequency of the vibrating ring 30 approaches the axial resonant frequency of the hub 10 because the vibrating ring 30 has the protrusion 36 means that if the protrusion 36 were removed from the vibrating ring 30, the radial resonant frequency of the vibrating ring 30 would move away from the axial resonant frequency of the hub 10. In this embodiment, the shape, dimensions and arrangement of the protrusions 36 are set (tuned) so that the radial resonance frequency of the vibration ring 30 approaches the axial resonance frequency of the hub 10. The radial resonance frequency of the vibration ring 30 is tuned to be within a range of ±10% of the axial resonance frequency of the hub 10 .

[0013] According to this embodiment, the vibrating ring 30 has a protrusion 36 protruding from the main body 31, so that the rigidity (resistance to vibration) of the vibrating ring 30 can be made anisotropic, and the vibrating ring 30 can be made to locally resonate in the radial direction at the same resonance frequency when the hub 10 resonates in the axial direction. Here, the local resonance of the vibrating ring 30 refers to a resonance mode in which the vibrating ring 30 itself deforms locally or overall, and is to be distinguished from a resonance mode in which the vibrating ring 30 reciprocates in a direction in which its center of gravity is located without substantially deforming. In addition, the radial resonance frequency of the vibrating ring 30 refers to the natural frequency of a mode in which the vibrating ring 30 itself locally resonates inward and outward in its radial direction. This forces the elastic body 20 holding the vibrating ring 30 to do work (repeated compression and expansion motion), increasing the damping force of the elastic body 20 and further reducing the vibration of the hub 10 itself, thereby reducing the sound radiated from the hub 10.

[0014] In this embodiment, unlike the technology of Patent Document 1, there is no need to provide a cavity in the hub 10, so sound radiation from the hub 10 can be reduced with greater versatility regardless of the size of the torsional damper.

[0015] This will be explained in more detail below. In the following description, the axial direction of the rotating shaft (crankshaft 61) is simply referred to as the axial direction, and the axis of the rotating shaft is simply referred to as the axis AX. In the direction of the axis AX, the tip side of the rotating shaft is simply referred to as the tip side or distal side D (see Figs. 3 and 4), and the base side of the rotating shaft is simply referred to as the base side or proximal side P (see Figs. 3 and 4). In addition, the direction perpendicular to the axis AX is simply referred to as the radial direction.

[0016] As shown in any one of Figures 1 to 3, the hub 10 has a fixed part 13 to which a rotating shaft (crankshaft 61 (Figure 4)) is fixed, a donut-shaped, disk-like stay 11 that protrudes radially outward from the fixed part 13, and a rim 12 that is disposed around the stay 11. The rim 12 constitutes the outer periphery (outermost periphery) of the hub 10. The stay 11 is formed in a disk shape that is perpendicular to the crankshaft 61, and connects the rim 12 and the fixed part 13.

[0017] The fixing portion 13 is formed, for example, in a cylindrical shape. The internal space of the fixing portion 13 serves as a mounting hole 14 into which the tip of the crankshaft 61 is inserted and fixed. When the torsional damper 100 is attached to the crankshaft 61, the axial direction of the crankshaft 61 and the axial direction of the mounting hole 14 coincide. More specifically, the axis of the mounting hole 14 coincides with the axis AX of the crankshaft 61. For example, a key groove 15 extending in the axial direction of the mounting hole 14 is formed at one location in the circumferential direction of the mounting hole 14. By striking a key (e.g., a rectangular metal block: not shown) so as to fit into both this key groove 15 and a key groove (not shown) formed in the crankshaft 61, the relative rotation between the crankshaft 61 and the torsional damper 100 is restricted, and the crankshaft 61 and the torsional damper 100 rotate integrally. That is, the hub 10 has a key groove 15 for connecting the hub 10 and a rotating shaft via a key in a state in which relative rotation between the hub 10 and the rotating shaft is restricted.

[0018] The plate surface of the stay 11 is perpendicular to the axial direction of the mounting hole 14. The stay 11 has, for example, a plurality of through holes 16 that penetrate the stay 11 in the thickness direction (the left-right direction in FIG. 3) and are arranged at equal intervals in the circumferential direction. 1, for example, these through holes 16 are formed to have the same shape and dimensions as one another and are disposed equidistant from the center C (FIG. 1) of the torsional damper 100 when viewed from the front. In the case of this embodiment, for example, as shown in FIG. 1, the stay 11 has four through holes 16 disposed at equal intervals in the circumferential direction of the torsional damper 100.

[0019] The rim 12 is formed in a cylindrical shape and is disposed coaxially with the fixing portion 13 . The cylindrical fixing portion 13 protrudes, for example, from the inner peripheral edge of the stay 11 toward the proximal side P. The rim 12 protrudes, for example, from the outer circumferential edge of the stay 11 toward both the proximal side P and the distal side D. For example, the protruding length of the rim 12 from the outer circumferential edge of the stay 11 to the proximal side P is smaller than the protruding length of the rim 12 from the outer circumferential edge of the stay 11 to the distal side D.

[0020] The elastic body 20 is formed in a cylindrical shape. The material of the elastic body 20 is, for example, rubber. The inner peripheral surface of the elastic body 20 is in close contact with the outer peripheral surface of the rim 12.

[0021] The main body 31 of the vibration ring 30 is formed, for example, in a cylindrical shape, and is disposed coaxially with the rim 12. The vibration ring 30 (main body 31) is fitted to the outer periphery of the hub 10 via the elastic body 20. The inner peripheral surface of the vibration ring 30 (the inner peripheral surface of the main body 31) is in close contact with the outer peripheral surface of the elastic body 20. The elastic body 20 is sandwiched between the inner peripheral surface of the vibration ring 30 (the inner peripheral surface of the main body 31) and the outer peripheral surface of the rim 12, and is compressed in the radial direction.

[0022] The dimension of the main body 31 in the axial direction is, for example, larger than the dimension of the rim 12 in the axial direction. For example, the base end face 33 of the main body 31 is located closer to the base end than the base end face of the rim 12. However, the present invention is not limited to this example, and the dimension of the main body 31 in the axial direction may be set to be equivalent to the dimension of the rim 12 in the axial direction.

[0023] In this embodiment, the torsional damper 100 also functions as a crank pulley. For this reason, a V-groove 35 is formed on the outer circumferential surface 34 of the main body 31 of the vibration ring 30. More specifically, a plurality of (e.g., six) V-grooves 35 are formed on the outer circumferential surface 34. Here, the outer circumferential surface 34 of the main body 31 has a formation region 34a where the V groove 35 is formed, and a non-formation region 34b where the V groove 35 is not formed. The non-formation region 34b is located, for example, closer to the tip side than the formation region 34a.

[0024] The entire hub 10 is integrally formed, for example, from a metal material. That is, the entire hub 10 including the stays 11, the rim 12, and the fixing portion 13 is integrally formed from a metal material.

[0025] The vibrating ring 30 is formed as a single unit, for example, from a metal material. That is, the entire vibrating ring 30 including the main body 31 and the protrusions 36 is formed as a single unit from a metal material.

[0026] As shown in FIG. 4, the torsional damper 100 is used by being attached to, for example, a crankshaft 61 of a vehicle engine. For example, with the tip of the crankshaft 61 fitted into the mounting hole 14 of the hub 10, the hub 10 is fixed to the crankshaft 61 using a fastener such as a bolt 65, thereby attaching the torsional damper 100 to the crankshaft 61.

[0027] As an example, the engine is an in-line 4-cylinder, 4-stroke engine. In this case, the engine has four cylinders arranged in series, and the reciprocating motion of the pistons reciprocating in the cylinders is converted into rotational motion via connecting rods and transmitted to the crankshaft 61. The sliding direction of the pistons is perpendicular to the axis AX of the crankshaft 61. The engine has a crank pin 62, a crank journal 63, a crank arm 64, and a counterbalance (not shown) for each cylinder. The position of the crank pin 62 is set so as to drive the first and fourth pistons counting from the torsional damper 100 side in phase with each other, and to drive the second and third pistons in phase with each other but 180 degrees out of phase with the first and fourth pistons.

[0028] In this embodiment, the torsional damper 100 has a V-groove 35 and also functions as a crank pulley. The V-groove 35 is for winding a power transmission belt around it to drive accessories such as a water pump and an air conditioner compressor. When the engine starts and the crankshaft 61 rotates, the torsional damper 100 also rotates, so that power is transmitted via the belt to the accessories such as the water pump and the air conditioner compressor.

[0029] Torsional damper 100 has a natural frequency in the torsional direction. Therefore, when torsional vibration occurs as crankshaft 61 rotates, if the natural frequency of torsional damper 100 in the torsional direction is tuned to match the torsional resonance frequency of crankshaft 61, the torsional vibration generated in crankshaft 61 can be absorbed by torsional damper 100 and reduced.

[0030] Not only torsional vibration but also axial vibration occurs in the crankshaft 61, and the axial vibration of the crankshaft 61 causes the hub 10 to resonate in the axial direction. In this embodiment, since the vibration ring 30 has the protrusions 36 as described above, the axial vibration of the hub 10 can be reduced, and the sound radiated from the hub 10 can be reduced.

[0031] In this embodiment, the protrusion 36 protrudes in the axial direction from the end face 32 of the main body 31 in the axial direction. More specifically, the protrusion 36 protrudes from the end face 32 on the tip side (distal side D) of the main body 31 to the distal side D. However, the present invention is not limited to this example, and the protrusion 36 may protrude from the end face 33 on the base end side (proximal side P) of the main body part 31 to the proximal side P. Also, the protrusion 36 may protrude radially outward from the outer peripheral surface 34 (particularly, the non-forming region 34b) of the main body part 31. Also, the vibrating ring 30 may have both a protrusion 36 protruding from the end face 32 on the tip end side (distal side D) of the main body part 31 of the vibrating ring 30 to the distal side D, and a protrusion 36 protruding from the end face 33 on the base end side (proximal side P) of the main body part 31 of the vibrating ring 30 to the proximal side P.

[0032] In this embodiment, the vibration ring 30 has a plurality of protrusions 36 that are arranged intermittently in the circumferential direction. This makes it possible to give the rigidity (resistance to vibration) of the vibrating ring 30 anisotropy at multiple points in the circumferential direction, making it possible to more easily and efficiently force the elastic body 20 to do work (repeated compression and expansion movements), thereby increasing the damping force of the elastic body 20 and reducing the sound radiated from the hub 10.

[0033] The vibrating ring 30 has three or more protrusions 36 . This makes it possible to give the rigidity of the vibrating ring 30 anisotropy at three or more points on the vibrating ring 30, making it possible to more easily and efficiently force the elastic body 20 to do work, thereby increasing the damping force of the elastic body 20 and reducing the sound radiated from the hub 10.

[0034] In this embodiment, the radial thickness dimension of the protrusion 36 (thickness dimension D1 shown in FIG. 3) is equal to the radial thickness dimension of the main body 31 (thickness dimension D2 shown in FIG. 3). Since the radial thickness dimension D1 of the protrusion 36 is equivalent to the radial thickness dimension D2 of the main body 31, the dimensions of the protrusion 36 can be sufficiently secured, and the presence of the protrusion 36 can more reliably impart anisotropy to the rigidity of the vibrating ring 30. Furthermore, when forming the protrusions 36 by lathe processing, the outer diameter and inner diameter of the protrusions 36 can be made equal to the inner diameter and outer diameter of the main body 31. That is, for example, as shown in Fig. 3, the position of the inner surface 36a of the protrusions 36 in the radial direction and the position of the inner surface 31a of the main body 31 in the radial direction can be made equal to each other, and the position of the outer surface 36b of the protrusions 36 in the radial direction and the position of the outer surface 31b of the main body 31 in the radial direction can be made equal to each other. This makes it easier to process the protrusions 36, and improves the manufacturability of the vibration ring 30. Here, the radial thickness dimension D1 of the protrusion portion 36 being equivalent to the radial thickness dimension D2 of the main body portion 31 means that the thickness dimension D1 is within ±20% of the thickness dimension D2 (thickness dimension D1 is 0.8 times or more and 1.2 times or less than the thickness dimension D2). In this embodiment, the radial thickness dimension D1 of the protrusion 36 and the radial thickness dimension D2 of the main body 31 are equal to each other.

[0035] In this embodiment, the dimension L1 (FIG. 1) of the protrusion 36 in the circumferential direction is greater than the thickness dimension D1 of the protrusion in the radial direction. This ensures that the weight and volume of the protrusion 36 are sufficient, allowing the vibration ring 30 to deform sufficiently greatly when resonating.

[0036] In this embodiment, the dimension L1 of the protrusion 36 in the circumferential direction is greater than the dimension of the protrusion 36 in the axial direction (the protrusion length D3 of the protrusion 36 (FIG. 3)). This also ensures sufficient weight and volume for the protrusions 36, allowing the vibrating ring 30 to deform sufficiently large during resonance. Here, if the protrusion length D3 of the protrusions 36 becomes excessively large, it is considered that the natural frequency of another deformation mode (local deformation of only the protrusions 36) will decrease, which may become a cause of new noise. However, in this embodiment, by increasing the circumferential dimension L1 of the protrusions 36 instead of the protrusion length D3, the main mode of the vibrating ring 30 can be generated at a desired natural frequency (for example, about 3000 Hz to 5000 Hz). However, if the dimension L1 in the circumferential direction of the protrusions 36 becomes too large and the intervals L21, L22, and L23 between adjacent protrusions 36 become small, the vibration ring 30 becomes difficult to resonate, so it is preferable that the intervals L21, L22, and L23 are larger than the dimension L1. More preferably, the total of the dimensions L1 of all the protrusions 36 (in the example of FIG. 1, dimension L1+dimension L1+dimension L1) is half or less of the circumferential length of the vibration ring 30 in the arrangement area of ​​the protrusions 36 (in the example of FIG. 1, dimension L1+dimension L1+dimension L1+interval L21+interval L22+interval L23).

[0037] In this embodiment, three or more protrusions 36 are arranged at equal intervals in the circumferential direction. This makes it possible to give the rigidity of the vibrating ring 30 anisotropy at three or more points in the circumferential direction, making it possible to more easily and efficiently force the elastic body 20 to do work, thereby increasing the damping force of the elastic body 20 and reducing the sound radiated from the hub 10. Here, the protrusions 36 being arranged at equal intervals in the circumferential direction means that the widest of the intervals L21, L22, and L23 between adjacent protrusions 36 in the circumferential direction is 1.2 times or less than the narrowest one. In this embodiment, the intervals L21, L22, and L23 are the same.

[0038] Here, four or more protrusions 36 may be arranged at equal intervals in the circumferential direction, but it is particularly preferable that the number of protrusions 36 on the vibrating ring 30 is three, and that the three protrusions 36 are arranged at equal intervals in the circumferential direction. In this embodiment, the multiple protrusions 36 are disposed, for example, at equal distances from the center C of the torsional damper 100. In this embodiment, the multiple protrusions 36 are formed to have the same shape and dimensions, and are positioned in a rotationally symmetrical relationship with respect to the center C. Therefore, the dimension L1 of each of the protrusions 36 is equal to each other.

[0039] As described above, in this embodiment, the number of through holes 16 is 4, and the number of protrusions 36 is 3. In other words, the number of through holes 16 and the number of protrusions 36 are relatively prime to each other. That is, in this embodiment, the hub 10 has a fixed portion 13 to which the rotating shaft is fixed, a plate-shaped stay 11 protruding radially outward from the fixed portion 13, and a rim 12 arranged around the stay 11, and the stay 11 has a plurality of through holes 16 that penetrate the stay 11 in the thickness direction and are arranged at equal intervals in the circumferential direction, and the number of through holes 16 and the number of protrusions 36 are mutually prime. This makes the deformation of the elastic body 20 more complex, and the effect of the elastic body 20 in damping the vibration of the vibrating ring 30 is enhanced. More specifically, when the four through holes 16 are arranged at equal intervals as in this embodiment, the hub 10 including the stays 11 has a deformation mode in which, for example, a state in which the hub 10 is elliptical in the vertical direction and a state in which the hub 10 is elliptical in the horizontal direction are alternately repeated. Also, when the three protrusions 36 are arranged at equal intervals, the vibrating ring 30 has three equally spaced deformation modes in the circumferential direction (described later with reference to Figs. 5 to 8). This makes the deformation of the elastic body 20 sandwiched between the hub 10 and the elastic body 20 more complex, and the effect of the elastic body 20 in damping the vibration of the vibrating ring 30 is enhanced. Here, the fact that the multiple through holes 16 are disposed at equal intervals in the circumferential direction means that the widest of the intervals L41, L42, L43, and L44 (FIG. 1) between adjacent through holes 16 in the circumferential direction is 1.2 times or less the narrowest. In this embodiment, the intervals L41, L42, L43, and L44 are the same as each other. Furthermore, when the number of through holes 16 and the number of protrusions are relatively prime to each other, the combination of the number of through holes 16 and the number of protrusions is not limited to 4 and 3 as in this embodiment. For example, the number of through holes 16 may be 3 and the number of protrusions may be 4, or the number of through holes 16 may be 4 and the number of protrusions may be 5.

[0040] In the present embodiment, the multiple through holes 16 are arranged, for example, at equal distances from the center C of the torsional damper 100. In this embodiment, the multiple through holes 16 are formed to have the same shape and dimensions, and are positioned in a rotationally symmetrical relationship with respect to the center C. Therefore, the dimension L3 of each of the through holes 16 in the circumferential direction is equal to each other.

[0041] Next, the results of a natural vibration analysis of the vibrating ring of the torsional damper according to the embodiment will be described with reference to FIGS. The vibrating ring 30 changes shape from the shape shown in FIG. 5 through the shape shown in FIG. 6 (undeformed state) and the shape shown in FIG. 7 to the shape shown in FIG. 8, and then alternately repeats these changes. The length of time required for the shape shown in FIG. 5 to change to the shape shown in FIG. 6 is equal to the length of time required for the shape shown in FIG. 6 to change to the shape shown in FIG. 8. After changing to the shape shown in Fig. 8, it passes through the shape shown in Fig. 6 and then changes again to the shape shown in Fig. 5. The length of time required for the shape shown in Fig. 8 to change to the shape shown in Fig. 6 is also equal to the length of time required for the shape shown in Fig. 6 to change to the shape shown in Fig. 5. FIG. 7 shows a timing exactly midway between the timing at which the shape shown in FIG. 6 results and the timing at which the shape shown in FIG. 8 results.

[0042] 5 to 8 show the analysis results when the end surface 33 (FIG. 3) of the vibrating ring 30 is restrained. In reality, as described above, the inner peripheral surface of the vibrating ring 30 is restrained by the elastic body 20, so the shapes (deformation of the vibrating ring 30) shown in FIGS. 5 to 8 differ from the actual shape, but they show deformation of the vibrating ring 30 with the same tendency as the actual deformation. 5 to 8 show the analysis results when the shape and dimensions of the protrusions 36 are tuned so that the radial resonance frequency of the vibrating ring 30 is approximately 3800 Hz, which is assumed to be the axial resonance frequency of the hub 10.

[0043] As shown in Figs. 5 to 8, the arrangement area of ​​each protrusion 36 in the vibration ring 30 and the surrounding area thereof repeatedly move alternately radially outward and radially inward in synchronization with each other. The portions between adjacent protrusions 36 also repeatedly deform in conjunction with the movement of the arrangement area of ​​each protrusion 36 and the surrounding area. In the state of FIG. 5, the arrangement area of ​​each protrusion 36 and its surrounding area are displaced radially outward, and in the state of FIG. 8, the arrangement area of ​​each protrusion 36 and its surrounding area are displaced radially inward. Therefore, in the state shown in Figure 5, the vibrating ring 30 has an approximately triangular shape with each protrusion 36 as a vertex, and in the state shown in Figure 8, the vibrating ring 30 has an approximately triangular shape with the midpoint between adjacent protrusions 36 as a vertex.

[0044] Here, in the example of Figures 5 to 8 (this embodiment), the vibrating ring 30 is reinforced by each protrusion 36, so that the arrangement area of ​​each protrusion 36 and a relatively wide portion around it displace radially outward and radially inward while "maintaining its shape as a surface." As a result, in an actual state in which the elastic body 20 exists on the inner periphery side of the vibration ring 30, the vibration ring 30 can sufficiently press the elastic body 20, strongly compressing it and deforming it. Therefore, as described above, the elastic body 20 holding the vibrating ring 30 is forced to work (repeated compression and expansion motion), thereby increasing the damping force of the elastic body 20 and further reducing the vibration of the hub 10 itself. As a result, the sound radiated from the hub 10 can be reduced.

[0045] 9 is a diagram showing the results of natural vibration analysis of the vibrating ring 300 of a torsional damper (not shown in its entirety) according to a comparative embodiment. The vibrating ring 300 differs from the vibrating ring 30 of the torsional damper 100 according to this embodiment only in that it does not have the protrusions 36. FIG. 9 also shows the analysis results when the proximal end face of the vibrating ring 300 is restrained. In the case of the vibration ring 300 of the torsional damper according to the comparative embodiment, the deformation of the vibration ring 300 is more localized. That is, instead of each apex of the triangle being locally displaced radially outward, the intermediate portion between the apexes of the triangle is recessed radially inward. Also, the amount of radially outward displacement is smaller than in Figs. 5 and 8. In other words, when the vibrating ring 300 does not have the protrusion 36 as in the comparative embodiment, the deformation of the vibrating ring 30 remains localized, making it difficult to apply a large compressive force to the elastic body 20 compared to the embodiment. In addition, the radial resonance frequency of the vibrating ring 300 in the case of FIG. 9 was about 4270 Hz.

[0046] Although the embodiments and modifications have been described above with reference to the drawings, these are merely examples of the present invention, and various configurations other than those described above can also be adopted.

[0047] For example, the torsional damper 100 is not limited to being used as a crank pulley, and may be used as, for example, a flywheel fixed to the crankshaft 61. In this case, the torsional damper 100 does not need to have the V-groove 35 (and the forming region 34a).

[0048] Further, in the above, an example has been described in which the torsional damper 100 is attached to an in-line four-cylinder engine, but the present invention is not limited to this example, and the torsional damper 100 can also be attached to and used in various types of engines, such as a six-cylinder engine or a V-type engine (such as a V8 engine), and in those cases, the same effects as those described above can be obtained.

[0049] Further, in the above, an example has been described in which the entire vibrating ring 30 (main body portion 31 and protrusion portion 36) is formed as a single unit, but the present invention is not limited to this example, and the main body portion 31 and the protrusion portion 36 may be formed separately, and the vibrating ring 30 may be formed by attaching the protrusion portion 36 to the main body portion 31.

[0050] Further, in the above, an example has been described in which the entire hub 10 (the stays 11, the rim 12 and the fixed portion 13) are formed as a single unit, but the present invention is not limited to this example, and any one or two of the stays 11, the rim 12 and the fixed portion 13 may be formed separately, and the hub 10 may be formed by assembling them together.

[0051] The present embodiment encompasses the following technical ideas. (1) A hub fixed to a rotating shaft; a ring-shaped vibration ring disposed along the outer periphery of the hub; a ring-shaped elastic body interposed between the vibration ring and the hub; A torsional damper comprising: The vibration ring has a ring-shaped main body and a protrusion protruding from the main body, A torsional damper in which the vibration ring has the protrusion, so that the radial resonance frequency of the vibration ring approaches the axial resonance frequency of the hub. (2) A torsional damper as described in (1), wherein the vibration ring has a plurality of the protrusions arranged intermittently in the circumferential direction. (3) A torsional damper according to (1) or (2), wherein the vibration ring has three or more of the protrusions. (4) A torsional damper as described in (3), in which three or more of the protrusions are arranged at equal intervals in the circumferential direction. (5) The hub is A fixing portion to which the rotating shaft is fixed; a plate-shaped stay protruding radially outward from the fixed portion; A rim disposed around the stay; having The stay has a plurality of through holes penetrating the stay in a thickness direction and arranged at equal intervals in a circumferential direction, The torsional damper according to (4), wherein the number of the through holes and the number of the protrusions are mutually prime. (6) A torsional damper as described in (1) or (2), wherein the protrusion protrudes in the axial direction from an end face of the main body in the axial direction. (7) A torsional damper as described in (6), wherein the radial thickness dimension of the protrusion is equal to the radial thickness dimension of the main body portion. (8) A torsional damper as described in (6), wherein the dimension of the protrusion in the circumferential direction is greater than the thickness dimension of the protrusion in the radial direction. [Explanation of symbols]

[0052] 10. Hub 11 Stay 12 Rims 13 Fixed part 14 Mounting hole 15 Keyway 16 Through hole 20 Elastic Body 30 Vibrating Ring 31 Main body 31a Inside 31b External surface 32 End face 33 End face 34 Outer surface 34a Formation area 34b Non-formation area 35 V groove 36 Protrusion 36a Inside 36b External surface 61 Crankshaft (rotating shaft) 62 Crank pin 63 Crank journal 64 Crank arm 65 volts 100 Torsional Damper 300 Vibrating Ring

Claims

1. A hub fixed to a rotating shaft; a ring-shaped vibration ring disposed along the outer periphery of the hub; a ring-shaped elastic body interposed between the vibration ring and the hub; A torsional damper comprising: The vibration ring has a ring-shaped main body and a protrusion protruding from the main body, A torsional damper in which the vibration ring has the protrusion, so that the radial resonance frequency of the vibration ring approaches the axial resonance frequency of the hub.

2. The torsional damper according to claim 1 , wherein the vibration ring has a plurality of the protrusions arranged intermittently in the circumferential direction.

3. The torsional damper according to claim 1 or 2, wherein the vibration ring has three or more of the protrusions.

4. 4. The torsional damper according to claim 3, wherein three or more of the protrusions are arranged at equal intervals in the circumferential direction.

5. The hub includes: A fixing portion to which the rotating shaft is fixed; a plate-shaped stay protruding radially outward from the fixed portion; A rim disposed around the stay; having The stay has a plurality of through holes penetrating the stay in a thickness direction and arranged at equal intervals in a circumferential direction, The torsional damper according to claim 4 , wherein the number of the through holes and the number of the protrusions are mutually prime.

6. The torsional damper according to claim 1 or 2, wherein the protrusion protrudes in the axial direction from an end face of the main body in the axial direction.

7. The torsional damper according to claim 6 , wherein a radial thickness dimension of the protrusion is equal to a radial thickness dimension of the main body.

8. The torsional damper according to claim 6 , wherein a dimension of the protrusion in a circumferential direction is greater than a thickness dimension of the protrusion in a radial direction.

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