Dynamic dumper and propeller shaft

Abstract

To provide a dynamic dumper and a propeller shaft which can suppress a decrease in holding force of a cylindrical member by a first elastic member.SOLUTION: In a dynamic dumper DD and a propeller shaft PS according to the present invention: a first end wall part 321 and a second end wall part 322 which are a pair of end wall parts are provided at both axial ends of an outer peripheral face 302 of a cylindrical member 3; a first elastic member 4 is bound by three faces of the outer peripheral face 302 of the cylindrical member 3, and first and second end wall parts 321, 322; and a radial length of the first elastic member 4 is larger than the first and second end wall parts 321, 322 of the cylindrical member 3 when viewed in a radial direction on a cross section cut in an axial direction. This can suppress a decrease in holding force of the cylindrical member 3 by the first elastic member 4 by suppressing a release of the first and second end wall parts 321, 322 in an axial direction of the first elastic member 4 even when the first elastic member 4 is cracked due to thermal aging.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a dynamic damper and a propeller shaft. [Background technology]

[0002] A known conventional dynamic damper is, for example, that described in Patent Document 1 below.

[0003] In brief, this dynamic damper comprises a cylindrical member housed on the inner circumferential side of the vibration-exciting member, a first elastic member provided on the outer circumferential side of the cylindrical member and elastically supporting the cylindrical member on the inner circumferential surface of the vibration-exciting member, a weight member disposed on the inner circumferential side of the cylindrical member, and a second elastic member interposed between the cylindrical member and the weight member and elastically supporting the weight member on the inner circumferential surface of the cylindrical member. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-216578 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the conventional dynamic damper, the first elastic member is released in the axial direction of the tubular member. Therefore, when cracks occur in the first elastic member due to thermal aging, the compressive force of the first elastic member is released, making it more likely to escape in the axial direction. This may result in a decrease in the holding force of the first elastic member, and there is still room for improvement.

[0006] Therefore, the present invention was devised in consideration of the technical problems with the conventional dynamic dampers, and aims to provide a dynamic damper and a propeller shaft that can suppress a decrease in the holding force of the cylindrical member by the first elastic member. [Means for solving the problem]

[0007] In one aspect of the present invention, the tubular member has end wall portions on the outer peripheral surfaces of both axial ends, and when viewed from the radial direction in a cross section cut in the axial direction, the radial length of the first elastic member is greater than the radial length of the end wall portions of the tubular member. [Effects of the Invention]

[0008] According to the present invention, it is possible to suppress a decrease in the holding force of the first elastic member for holding the tubular member. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a half cross-sectional view taken along the direction of the rotation axis of a propeller shaft equipped with a dynamic damper according to the present invention. [Figure 2] 1 is a perspective view of a dynamic damper according to a first embodiment of the present invention. [Figure 3] FIG. 3 is a front view of the dynamic damper shown in FIG. 2. [Figure 4] FIG. 4 is a cross-sectional view taken along line AA in FIG. [Figure 5] FIG. 5 is an axial cross-sectional view of the propeller shaft showing the mounting state of the dynamic damper shown in FIG. 4. [Figure 6] FIG. 5 is an axial cross-sectional view of a dynamic damper according to a second embodiment of the present invention. [Figure 7] FIG. 7 is an axial cross-sectional view of the propeller shaft showing the mounting state of the dynamic damper shown in FIG. 6. [Figure 8] FIG. 10 is an axial cross-sectional view of a dynamic damper according to a third embodiment of the present invention. [Figure 9] FIG. 9 is a cross-sectional view in the axial direction of the propeller shaft showing the mounting state of the dynamic damper shown in FIG. 8. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of a dynamic damper and a propeller shaft according to the present invention will be described in detail with reference to the drawings. Note that in the following embodiments, the dynamic damper and propeller shaft will be described as being applied to a propeller shaft for an automobile, as in the prior art. In other words, the dynamic damper according to the present invention can be applied to various vibration-exciting members in addition to the propeller shaft for an automobile exemplified in this embodiment.

[0011] [First embodiment] 1 to 5 show a first embodiment of a dynamic damper and a propeller shaft according to the present invention. In the following description, for convenience, the left side of Fig. 1 will be referred to as the "front" and the right side as the "rear," and the direction along the rotation axis Z in Fig. 1 to 5 will be referred to as the "axial direction," the direction perpendicular to the rotation axis Z as the "radial direction," and the direction around the rotation axis Z as the "circumferential direction."

[0012] (Propeller shaft configuration) FIG. 1 shows a half cross-sectional view of a propeller shaft for an automobile to which the present invention is applied, taken along the direction of a rotation axis Z.

[0013] 1, the propeller shaft PS according to this embodiment mainly includes a first joint J1, a first shaft S1, a second joint J2, a second shaft S2, and a third joint J3. The propeller shaft PS has a middle portion supported by a vehicle body (not shown) by a well-known center bearing CB that is suspended from the vehicle body (not shown) via a bracket BKT.

[0014] The first joint J1 and the second joint J2 are both well-known Cardan joints serving as universal joints. The first joint J1 is located at the front end of the propeller shaft PS and connects the first shaft S1 to the drive source side of the vehicle, such as a transmission output shaft (not shown). The second joint J2 is located at the rear end of the propeller shaft PS and connects the second shaft S2 to the drive wheel side of the vehicle, such as a differential input shaft (not shown). The third joint J3 is a sliding constant velocity joint known as a tripod joint and is located in the middle of the propeller shaft PS, connecting the first shaft S1 and the second shaft S2 so that they can rotate at a constant speed. In other words, the propeller shaft PS transmits rotational force from the drive source side to the drive wheels side of the vehicle.

[0015] Furthermore, the first shaft S1 and the second shaft S2 each have a first tube 1 and a second tube 2 formed in a generally cylindrical shape, and correspond to the vibration excitation members according to the present invention, which vibrate in response to external inputs from the vehicle (not shown). A dynamic damper DD that suppresses vibration of the first shaft S1 and the second shaft S2 is provided on the inner periphery of each of the first tube 1 and the second tube 2. That is, the dynamic damper DD, which serves as a dynamic vibration absorber, is fixed by press-fitting to the inner periphery of each of the first shaft S1 and the second shaft S2.

[0016] (Dynamic damper configuration) Fig. 2 shows a perspective view of the dynamic damper DD according to this embodiment. Fig. 3 shows a front view of the dynamic damper DD shown in Fig. 2. Fig. 4 shows an axial cross-sectional view of the dynamic damper DD taken along line AA in Fig. 3. Fig. 5 shows an enlarged cross-sectional view of a main part in the axial direction of the propeller shaft PS, showing the installation state of the dynamic damper DD shown in Fig. 4.

[0017] For example, as shown in Figures 2 to 5, the dynamic damper DD comprises a tubular member 3 formed in a generally cylindrical shape, a first elastic member 4 that elastically supports the tubular member 3 on the inner surfaces 10, 20 of the first tube 1 and the second tube 2, respectively, a weight member 5 arranged on the inner side of the tubular member 3, and a second elastic member 6 that elastically supports the weight member 5 on the inner surface 301 of the tubular member 3.

[0018] The cylindrical member 3 integrally includes a cylindrical base 31 that is continuous in an endless manner along the circumferential direction, and a pair of end walls, a first end wall 321 and a second end wall 322, that are provided at both axial ends of the cylindrical base 31 and extend radially outward from the outer circumferential surface 302 of the cylindrical base 31. In other words, the cylindrical member 3 is formed so that its cross section is generally U-shaped and opens radially outward, because the cylindrical base 31, the first end wall 321, and the second end wall 322 are integrally formed.

[0019] The cylindrical base 31 is made of a metal material and is formed in a generally cylindrical shape, extending in the axial direction along the rotation axis Z of the propeller shaft PS. The cylindrical base 31 has an outer diameter smaller than the inner diameters of the first tube 1 and the second tube 2, and is configured to form a predetermined radial gap C1 between the first tube 1 and the second tube 2. The cylindrical base 31 also has a constant inner diameter along the axial direction, and has a cylindrical space 33 inside that opens on both sides in the axial direction.

[0020] The first end wall portion 321 and the second end wall portion 322 extend radially outward generally perpendicular to the outer peripheral surface 302 of the cylindrical base 31 so that the angle (minor angle) θ between them and the outer peripheral surface 302 is generally 90°, and are provided around the entire circumference of the cylindrical member 3. The first end wall portion 321 and the second end wall portion 322 are formed to have a height (radial length Tp) that is equal to or greater than half the thickness (radial length Tg) of the first elastic member 4. In other words, the first end wall portion 321 and the second end wall portion 322 are formed so that a radial gap C2 between the first end wall portion 321 and the second end wall portion 322 and the inner peripheral surfaces 10, 20 of the first tube 1 and the second tube 2 is equal to or less than half the radial gap C1 between the cylindrical base 31 and the inner peripheral surfaces 10, 20 of the first tube 1 and the second tube 2.

[0021] The first end wall portion 321 and the second end wall portion 322 are formed flat such that their tip surfaces 321a and 322a are generally parallel to the inner circumferential surfaces 10 and 20 of the first tube 1 and the second tube 2. Furthermore, in this embodiment, the tip surfaces 321a and 322a of the first end wall portion 321 and the second end wall portion 322 are connected to the inner side surfaces 321b and 322b and the outer side surfaces 321c and 322c via corners 331 and 332 that are generally right-angled, respectively.

[0022] The first elastic member 4 is made of an elastically deformable material, such as a rubber material, and is formed in an endless shape that is continuous in the circumferential direction. The first elastic member 4 is provided along the outer peripheral surface 302 of the tubular member 3 and surrounds the outer peripheral surface 302 of the tubular base 31. The first elastic member 4 is set to have a thickness (radial length Tg) that is greater than the radial gap C1 between the first tube 1 and the second tube 2 and the tubular member 3. With this configuration, the dynamic damper DD is fixed by press-fitting to the inner peripheral surfaces 10 and 20 of the first tube 1 and the second tube 2, respectively. As a result, the first elastic member 4 is compressively deformed between the inner peripheral surfaces 10 and 20 of the first tube 1 and the second tube 2 and the outer peripheral surface 302 of the tubular member 3, and elastically supports the tubular member 3 at the inner peripheral surfaces 10 and 20 of the first tube 1 and the second tube 2.

[0023] The first elastic member 4 is formed so that its axial width gradually decreases toward the outer periphery and its cross section is generally trapezoidal, thereby preventing the first elastic member 4 from protruding from the radial gap C2 between the first tube 1 and the second tube 2 and the first end wall portion 321 and the second end wall portion 322 during elastic deformation when the dynamic damper DD is attached to the inner periphery of the first tube 1 and the second tube 2 (see FIG. 5).

[0024] The weight member 5 is made of a metal material and is formed into a generally cylindrical shape, and is set to a weight that can suppress vibrations of the vibration-exciting members, the first tube 1 and the second tube 2. Since it is necessary to ensure a certain radial gap Cx between the weight member 5 and the cylindrical member 3, the weight of the weight member 5 is adjusted by increasing or decreasing the axial length L of the weight member 5.

[0025] The second elastic member 6 is formed endlessly and circumferentially continuous, and is interposed radially between the cylindrical member 3 and the weight member 5 over the entire circumference. The second elastic member 6 is made of an elastically deformable material, such as a rubber material, and integrally includes an outer peripheral portion 61, an inner peripheral portion 62, and a connecting portion 63 that connects the outer peripheral portion 61 and the inner peripheral portion 62. The outer peripheral portion 61 has an axial width equal to the axial width of the inner peripheral surface 301 of the cylindrical member 3, extends over the entire axial area of ​​the inner peripheral surface 301 of the cylindrical member 3, and is fixed to the inner peripheral surface 301 of the cylindrical member 3 by a predetermined fixing method, such as vulcanization bonding. The inner peripheral portion 62 is disposed opposite the inner peripheral side of the outer peripheral portion 61, and is fixed to the outer peripheral surface 50 of the weight member 5 by a predetermined fixing method, such as vulcanization bonding. The connecting portion 63 integrally includes thick portions 631 arranged at approximately equal intervals in the circumferential direction, and thin membrane-like portions 632 provided between the thick portions 631 in the circumferential direction and connecting the thick portions 631 together.

[0026] (Effects of this embodiment) As described above, in the conventional dynamic damper DD, the first elastic member 4 is released in the axial direction of the cylindrical member 3. Therefore, when cracks occur in the first elastic member 4 due to thermal aging, the compressive force of the first elastic member 4 is released and the first elastic member 4 is likely to escape in the axial direction. This may result in a decrease in the holding force of the first elastic member 4, and there is still room for improvement.

[0027] In contrast, in the dynamic damper DD and propeller shaft PS according to this embodiment, a pair of end walls, a first end wall 321 and a second end wall 322, are provided at both axial ends of the outer peripheral surface 302 of the cylindrical member 3, and the first elastic member 4 is constrained by three surfaces consisting of the outer peripheral surface 302 of the cylindrical member 3 and the first end wall 321 and the second end wall 322. In other words, by providing the first end wall 321 and the second end wall 322, the radial gap C2 between the inner peripheral surfaces 10 and 20 of the first tube 1 and the second tube 2 and the tip end surfaces 321 a and 322 a of the first end wall 321 and the second end wall 322, which exposes the first elastic member 4 to the outside, is reduced compared to the radial gap C1 between the inner peripheral surfaces 10 and 20 of the first tube 1 and the second tube 2 and the outer peripheral surface 302 of the cylindrical base 31, which corresponds to the conventional open state. Therefore, even if a crack occurs in the first elastic member 4 due to thermal aging, the first end wall portion 321 and the second end wall portion 322, in other words, the reduced radial gap C2, prevents the first elastic member 4 from escaping in the axial direction. This makes it possible to prevent a decrease in the holding force of the first elastic member 4 for holding the tubular member 3.

[0028] Furthermore, in this embodiment, a pair of end walls, the first end wall 321 and the second end wall 322, are provided around the entire circumference of the tubular member 3. As a result, when a crack occurs in the first elastic member 4 due to thermal aging, it is possible to prevent the first elastic member 4 from escaping in the axial direction around the entire circumference of the tubular member 3, and it is possible to effectively prevent a decrease in the holding force of the first elastic member 4 for the tubular member 3.

[0029] Furthermore, in this embodiment, the height (radial length Tp) of the pair of end walls, the first end wall 321 and the second end wall 322, is set to be equal to or greater than half the thickness (radial length Tg) of the tubular member 3. This makes it possible to make relatively small the radial gap C2 between the inner circumferential surfaces 10, 20 of the first tube 1 and the second tube 2, which correspond to the excitation members, and the first end wall 321 and the second end wall 322. This makes it possible to more effectively prevent the first elastic member 4 from escaping in the axial direction when cracks occur in the first elastic member 4 due to thermal aging.

[0030] In addition, in this embodiment, the pair of end walls, the first end wall portion 321 and the second end wall portion 322, are configured to extend perpendicularly radially outward relative to the outer peripheral surface 302 of the cylindrical member 3 so that the angle (minor angle) θ between them and the outer peripheral surface 302 of the cylindrical base 31 is approximately 90°. Therefore, the first end wall portion 321 and the second end wall portion 322 appropriately suppress axial escape of the first elastic member 4 when cracks occur in the first elastic member 4 due to thermal aging, thereby effectively suppressing a decrease in the holding force of the first elastic member 4 for the cylindrical member 3 and ensuring good productivity of the dynamic damper DD.

[0031] Second Embodiment 6 and 7 show a second embodiment of the dynamic damper and propeller shaft according to the present invention, in which the configuration of the pair of end wall portions according to the present invention (the first end wall portion 321 and the second end wall portion 322 according to the first embodiment) is modified. Note that the basic configuration other than these modifications is the same as that of the first embodiment, and therefore the same components as those in the first embodiment are denoted by the same reference numerals and description thereof will be omitted.

[0032] That is, in this embodiment, the tip surfaces 321a, 322a and inner surfaces 321b, 322b of a pair of end wall portions, the first end wall portion 321 and the second end wall portion 322, which were configured as corner portions in the first embodiment, are connected by R-chamfered portions 341, 342 whose cross sections are arc-shaped.

[0033] As described above, in this embodiment, the first end wall portion 321 and the second end wall portion 322 serving as a pair of end walls each have R-chamfered portions 341, 342 having an arc-shaped axial cross section at the inner edge of the tip portion facing the first elastic member 4. That is, with respect to the first end wall portion 321 and the second end wall portion 322, the tip surfaces 321a, 322a and the inner surfaces 321b, 322b of the first end wall portion 321 and the second end wall portion 322 are connected by the R-chamfered portions 341, 342 having an arc-shaped transverse cross section. This makes it possible to suppress stress concentration on the first end wall portion 321 and the second end wall portion 322 relative to the first elastic member 4 when the first elastic member 4 elastically deforms, and to suppress the expansion of cracks that occur in the first elastic member 4 due to thermal aging.

[0034] Third Embodiment 8 and 9 show a third embodiment of the dynamic damper and propeller shaft according to the present invention, in which the configuration of the pair of end wall portions according to the present invention (the first end wall portion 321 and the second end wall portion 322 according to the first embodiment) is modified. Note that the basic configuration other than these modifications is the same as that of the first embodiment, and therefore the same components as those in the first embodiment are denoted by the same reference numerals and description thereof will be omitted.

[0035] That is, in this embodiment, the tip ends 321d, 322d of the pair of end wall portions, the first end wall portion 321 and the second end wall portion 322, extend in an inclined manner so as to be inclined radially outward and axially inward relative to the outer circumferential surface 302 of the tubular member 3. Specifically, the tip ends 321d, 322d of the first end wall portion 321 and the second end wall portion 322 are inclined axially inward at an inclination angle θ that follows the tapered axial end faces of the first elastic member 4, whose axial width gradually decreases toward the outer circumferential side in a free state. Note that this embodiment illustrates an example in which only the tip ends 321d, 322d of the first end wall portion 321 and the second end wall portion 322 are inclined as one aspect of the present invention in which the first end wall portion 321 and the second end wall portion 322 are inclined. However, the entire first end wall portion 321 and the second end wall portion 322 may be inclined axially inward.

[0036] In this manner, in the present embodiment, the tip ends 321d, 322d of the first end wall 321 and the second end wall 322 serving as a pair of end walls are inclined so as to be inclined axially inward. Therefore, compared to the first embodiment in which the first end wall 321 and the second end wall 322 extend vertically, the outer corners 321e, 322e of the tip ends 321d, 322d of the first end wall 321 and the second end wall 322 protrude radially outward, thereby making it possible to reduce the radial gap C2 between the inner circumferential surfaces 10, 20 of the first tube 1 and the second tube 2 and the first end wall 321 and the second end wall 322 (see FIG. 9 ). This more effectively prevents the first elastic member 4 from escaping in the axial direction through the radial gap C2 between the inner surfaces 10, 20 of the first tube 1 and the second tube 2 and the first end wall portion 321 and the second end wall portion 322 when cracks occur in the first elastic member 4 due to thermal aging, thereby more effectively preventing a decrease in the holding force of the first elastic member 4.

[0037] The present invention is not limited to the configurations of the dynamic damper DD and the propeller shaft PS exemplified in the above-described embodiments, and can be freely modified depending on the specifications of the dynamic damper and the propeller shaft to which the present invention is applied, as long as the configuration can achieve the above-described effects of the present invention. [Explanation of symbols]

[0038] 1...first tube (excitation member), 2...second tube (excitation member), 3...cylindrical member, 301...inner peripheral surface, 302...outer peripheral surface, 31...cylindrical base portion, 331...first end wall portion (pair of end wall portions), 332...second end wall portion (pair of end wall portions), 331a, 332a...tip surface, 331b, 332b...inner surface, 331c, 332c...outer surface, 341, 342...R-chamfered portion, 4...first elastic member, 5...weight member, 6...second elastic member, Tg...radial length, Tp...radial length, DD...dynamic damper, PS...propeller shaft,

Claims

1. a cylindrical member accommodated on the inner circumferential side of the cylindrical vibration generating member; a first elastic member provided on an outer circumferential surface of the cylindrical member and elastically supporting the cylindrical member on an inner circumferential surface of the vibration excitation member; a weight member disposed on the inner circumferential side of the cylindrical member; a second elastic member that elastically supports the weight member on an inner circumferential surface of the cylindrical member; Equipped with the cylindrical member has a pair of end wall portions at both axial ends thereof, the end wall portions extending radially outward from an outer circumferential surface of the cylindrical member; When viewed from the radial direction in the cross section cut in the axial direction, the radial length of the first elastic member is greater than the radial length of the pair of end wall portions. A dynamic damper characterized by:

2. 2. The dynamic damper according to claim 1, The pair of end wall portions are provided around the entire circumference of the cylindrical member. A dynamic damper characterized by:

3. 2. The dynamic damper according to claim 1, The radial length of the pair of end wall portions is set to be equal to or greater than half of the radial length of the cylindrical member. A dynamic damper characterized by:

4. 2. The dynamic damper according to claim 1, The pair of end wall portions extend perpendicularly to the outer circumferential surface of the cylindrical member in the radial direction. A dynamic damper characterized by:

5. 2. The dynamic damper according to claim 1, the pair of end wall portions extend obliquely so as to be inclined outward in the radial direction and inward in the axial direction with respect to an outer circumferential surface of the cylindrical member; A dynamic damper characterized by:

6. The dynamic damper according to any one of claims 1 to 5, Each of the pair of end wall portions has an R-chamfered portion on an inner edge of a tip end portion facing the first elastic member, the R-chamfered portion having an arc-shaped cross section in the axial direction. A dynamic damper characterized by:

7. a cylindrical tube supported on the vehicle body and transmitting rotational force; a cylindrical member accommodated on the inner circumferential side of the tube; a first elastic member provided on an outer circumferential surface of the cylindrical member and elastically supporting the cylindrical member on an inner circumferential surface of the vibration excitation member; a weight member disposed on the inner circumferential side of the cylindrical member; a second elastic member that elastically supports the weight member on an inner circumferential surface of the cylindrical member; Equipped with the cylindrical member has a pair of end wall portions at both ends of the cylindrical member in the direction of the rotation axis of the tube, the end wall portions extending radially outward from the outer circumferential surface of the cylindrical member in the direction of the rotation axis, The radial length of the first elastic member is greater than the radial length of the pair of end wall portions. A propeller shaft characterized by:

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