JP2012241822A - Dynamic damper for hollow shaft - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dynamic damper that can secure excellent dynamic vibration absorption characteristics in a low-frequency region and further improve the versatility of an elastic body in the tuning of the dynamic vibration absorption characteristics.SOLUTION: The dynamic damper includes a mass body 11 freely inserted to the inner periphery of a hollow shaft 2 that is a vibration reducing object; a pair of elastic bodies 12 composed of a rubber elastic material, which are disposed on both axial sides of the mass body 11 with outer diameter parts thereof being fitted to the inner peripheral surface of the hollow shaft 2; and an insert member 13 which is inserted to the inner periphery of the mass body 11 to connect one axial end of each elastic body 12 to the mass body 11.

Description

  The present invention relates to a dynamic damper that is attached to an inner circumferential space of a hollow shaft, such as a propeller shaft of an automobile, and suppresses vibration and noise generated in the hollow shaft.

  Typical conventional technology of a dynamic damper that is installed in the inner space of the propeller shaft that transmits the driving force output from the engine of the automobile via the transmission to the rear wheels and suppresses vibration and noise generated in the propeller shaft Are disclosed in Patent Documents 1 to 4 below.

  Among them, the dynamic damper disclosed in Patent Document 1 is an outer press-fitted into the inner periphery of the propeller shaft 100 via an elastic layer 104 made of a rubber material or a synthetic resin material having rubber-like elasticity, as shown in FIG. An elastic body 103 made of a rubber material or a synthetic resin material having rubber-like elasticity is interposed between the ring 101 and a metal mass body 102 arranged on the inner periphery thereof, and the elastic body 103 has a circumferential direction or the like. The mass body 102 is elastically connected to the outer ring 101 by a plurality of elastic support portions 103a formed at intervals. According to this configuration, the elastic support portion 103a of the elastic body 103 that elastically supports the mass body 102 on the outer ring 101 serves as a compression spring against the input vibration in the direction perpendicular to the axis. In order to reduce the spring constant of the elastic support portion 103a in order to ensure the vibration absorption characteristics, it is necessary to reduce the volume of the elastic support portion 103a. For this reason, the durability of the elastic support portion 103a is lowered and is easily broken. There is concern.

  On the other hand, as shown in FIG. 10, the dynamic damper disclosed in Patent Document 2 has an inner periphery of the propeller shaft 200 on both sides in the axial direction of the metal mass body 202 that is loosely inserted into the inner periphery of the propeller shaft 200. A cylindrical elastic body 201 that is press-contacted to the surface is integrally molded. Since the elastic body 201 becomes a shear spring against the input vibration in the direction perpendicular to the axis, the spring constant is reduced and the low frequency region is used. It is possible to ensure excellent dynamic vibration absorption characteristics.

  In addition, as shown in FIG. 11, the dynamic damper disclosed in Patent Document 3 includes a propeller shaft that is press-fitted with fixing metal fittings 303 on both sides in the axial direction of a metal mass body 302 that is loosely inserted into the inner periphery of the propeller shaft 300. A cylindrical elastic body 301 that is pressed against the inner peripheral surface of 300 is integrally formed. Like the dynamic damper shown in FIG. 10, the elastic body 301 becomes a shear spring against input vibration in the direction perpendicular to the axis. is there.

  Further, the dynamic damper disclosed in Patent Document 4 is the same, and as shown in FIG. 12, the propeller shaft 400 is provided on both sides in the axial direction of the metal mass body 402 that is loosely inserted into the inner periphery of the propeller shaft 400. An annular elastic body 401 press-contacted to the inner peripheral surface is integrally formed, and the elastic body 401 serves as a shear spring against input vibration in the direction perpendicular to the axis.

JP-A-9-53686 JP 2007-177830 A JP-A-5-149386 JP 2003-294025 A

  However, in any of the dynamic dampers shown in FIGS. 10 to 12 (Patent Documents 2 to 4), since the elastic body becomes a shear spring against the input vibration in the direction perpendicular to the axis, even in the low frequency region, even if the volume is increased. Excellent dynamic vibration-absorbing characteristics can be secured, and therefore durability can be improved, and it is advantageous in terms of releasability from the mold after vulcanization molding. Therefore, the axial size of the dynamic damper as a whole becomes longer, the mold structure becomes complicated, and productivity is easily restricted.

  Also, when changing the stiffness (spring constant) of the elastic body and the weight (shape) of the mass body in order to tune the dynamic vibration absorption characteristics by the resonance frequency of the dynamic damper, the size and shape of the mass body are changed. In each case, it is necessary to manufacture a mold for integrally molding an elastic body to a mass body, that is, there is a problem that the versatility of the mold is poor and therefore the cost is increased.

  The present invention has been made in view of the above points, and its technical problem is to ensure excellent dynamic vibration absorption characteristics in a low frequency region and to tune dynamic vibration absorption characteristics. An object of the present invention is to provide a dynamic damper capable of improving the versatility of an elastic body.

  As a means for effectively solving the technical problem described above, a hollow shaft dynamic damper according to the invention of claim 1 includes a mass body loosely inserted on an inner periphery of a hollow shaft to be reduced in vibration, A pair of elastic bodies made of a rubber-like elastic material that is arranged on both sides in the axial direction and whose outer diameter portion is fitted to the inner peripheral surface of the hollow shaft, and inserted into the inner periphery of the mass body, And an insertion member for coupling one end in the axial direction to the mass body. The rubber-like elastic material here is a rubber material or a synthetic resin material having rubber-like elasticity.

  The dynamic damper having the above-described configuration can be easily assembled by coupling a pair of elastic bodies formed separately from the mass body to both sides in the axial direction of the mass body via insertion members. And, since the elastic body is coupled to the mass body at one end in the axial direction and the outer diameter portion is fitted to the inner peripheral surface of the hollow shaft, it becomes a shear spring against the input vibration in the direction perpendicular to the axis. The spring constant can be set low. For this reason, excellent dynamic vibration absorption characteristics in the low frequency region are secured, and it is not necessary to reduce the volume of the elastic body in order to lower the spring constant as in the case of supporting the mass body in the compression direction. The durability of the elastic body can be improved.

  In addition to the elastic body being molded separately from the mass body, the insertion member that couples the mass body and the elastic body also functions as part of the mass in the spring-mass system using the elastic body as a spring. When tuning the dynamic vibration absorption characteristics (resonance frequency of the dynamic damper), it is not necessary to manufacture a mold for integrally molding the elastic body to the mass body every time the size or shape of the mass body is changed. As a result, the versatility of the metal mold | die which shape | molds this elastic body can be improved.

  The dynamic damper for a hollow shaft according to the invention of claim 2 is characterized in that, in the configuration described in claim 1, the elastic body is integrally vulcanized and bonded to the insertion member.

  According to the above configuration, since the elastic body and the insertion member are integrated by vulcanization adhesion in advance, it is only necessary to couple the insertion member integral with the elastic body to the mass body at the time of assembly. It becomes easy. Further, since the insertion member may be sufficiently smaller than the mass body, it is possible to prevent an increase in the size of the mold for integrally molding the elastic body with the insertion member.

  A dynamic damper for a hollow shaft according to a third aspect of the invention is characterized in that, in the configuration described in the first or second aspect, the mass body, the elastic body and the insertion member are cylindrical or annular.

  According to the above configuration, even if cleaning liquid or the like enters the inner circumferential space of the hollow shaft, it is easily discharged through the inner circumference of the cylindrical or annular mass body, the elastic body, and the insertion member. It is possible to prevent the cleaning liquid and the like from remaining in the peripheral space.

  According to the dynamic damper for a hollow shaft according to the present invention, excellent dynamic vibration absorption characteristics in a low frequency region can be secured, and the dynamic vibration absorption characteristics can be tuned separately from an elastic body by a mass body or an insertion member. Therefore, the versatility of the mold for molding the elastic body can be improved, and the elastic body made of a rubber-like elastic material is integrally vulcanized in the mass body. Since it is not bonded, the mass body can be easily recycled after it is discarded.

It is sectional drawing which cuts and shows 1st embodiment of the dynamic damper for hollow shafts which concerns on this invention by the plane which passes along an axial center. It is a cross-sectional perspective view of the state before the assembly which cuts and shows the dynamic damper for hollow shafts of 1st embodiment by the plane which passes along an axial center. It is a cross-sectional perspective view of the assembly state which cut | disconnects and shows the dynamic damper for hollow shafts of 1st embodiment by the plane which passes along an axial center. It is sectional drawing which cuts and shows 2nd embodiment of the dynamic damper for hollow shafts which concerns on this invention by the plane which passes along an axial center. It is sectional drawing of the state before the assembly which cuts and shows the dynamic damper for hollow shafts of 2nd Embodiment by the plane which passes along an axial center. It is sectional drawing which cut | disconnects and shows 3rd embodiment of the dynamic damper for hollow shafts which concerns on this invention by the plane which passes along an axial center. It is a cross-sectional perspective view of the state before the assembly which shows the dynamic damper for hollow shafts of 3rd Embodiment cut | disconnected by the plane which passes along an axial center. It is a cross-sectional perspective view of the assembly state which cut | disconnects and shows the dynamic damper for hollow shafts of 3rd embodiment by the plane which passes along an axial center. It is sectional drawing which cuts and shows an example of the conventional dynamic damper for hollow shafts in the plane which passes along an axial center. It is a cross-sectional perspective view which cuts and shows the other example of the conventional dynamic damper for hollow shafts in the plane which passes along an axial center. It is sectional drawing which cuts and shows the other example of the conventional dynamic damper for hollow shafts in the plane which passes along an axial center. It is sectional drawing which cuts and shows the other example of the conventional dynamic damper for hollow shafts in the plane which passes along an axial center.

  Hereinafter, preferred embodiments of a dynamic damper for a hollow shaft according to the present invention will be described with reference to the drawings. 1 to 3 show a first embodiment.

  In FIG. 1, reference numeral 1 is a dynamic damper, and 2 is a propeller shaft of an automobile. The propeller shaft 2 corresponds to the hollow shaft described in claim 1, that is, has a hollow cylindrical shape, and the dynamic damper 1 is attached to the inner circumferential space of the propeller shaft 2.

  The dynamic damper 1 includes a mass body 11 that is loosely inserted into the inner periphery of the propeller shaft 2 to be reduced in vibration, and is disposed on both sides in the axial direction of the mass body 11, and an outer diameter portion 12 a is an inner peripheral surface 2 a of the propeller shaft 2. A pair of elastic bodies 12 made of a rubber-like elastic material (rubber material or a synthetic resin material having rubber-like elasticity) to be fitted on the inner surface of the elastic body 12 and the mass body 11. And a pair of insertion members 13 that are inserted into the inner periphery and couple one end of the elastic body 12 in the axial direction to the mass body 11.

  The mass body 11 is made of, for example, a relatively thick cylindrical body made of metal, has a required axial length, and has an outer peripheral surface formed with a smaller diameter than the inner peripheral surface 2 a of the propeller shaft 2. Yes. Further, chamfers 11 a are formed on the inner peripheral edges of both ends in the axial direction of the mass body 11.

  The elastic body 12 has an annular shape, and the outer diameter portion 12 a is formed to have a larger diameter than the outer diameter of the mass body 11 and has an appropriate margin for the inner peripheral surface 2 a of the propeller shaft 2. Further, one end of the elastic body 12 in the axial direction is integrally vulcanized and bonded to the outer peripheral surface of the insertion member 13, and the bonded portion 12b is appropriately tightened to the inner peripheral surface 11b of the mass body 11. A cylindrical elastic membrane portion 12c having a margin is extended. And between the said adhesion part 12b and the outer-diameter part 12a, it is the spring part 12d which receives a shear deformation mainly with the relative displacement of the propeller shaft 2 and the mass body 11 at the axis orthogonal direction. The outer diameter portion 12a is divided in the circumferential direction by a plurality of recesses 12e.

  The insertion member 13 is made of a metal cylinder, and its outer peripheral surface has a smaller diameter than the inner peripheral surface 11 b of the mass body 11. As shown in FIG. 2, the integrally molded product including the elastic body 12 and the insertion member 13 positions and sets the insertion member 13 in a mold for vulcanization molding (not shown), and from the outer peripheral side of the insertion member 13. The annular cavity defined by the die is filled with unvulcanized rubber material toward the outer peripheral side on the one side in the axial direction, and heated and pressurized to be inserted simultaneously with the vulcanization molding of the elastic body 12. The member 13 is vulcanized and bonded to the outer peripheral surface.

  That is, as shown in FIG. 2, the dynamic damper 1 inserts the insertion member 13 in the integrally formed product of the elastic body 12 and the insertion member 13 into the inner periphery of the mass body 11 from both sides in the axial direction. As shown in FIG. 3, the elastic film portion 12 c of the elastic body 12 vulcanized and bonded to the outer peripheral surface 13 is press-fitted into the inner peripheral surface 11 b of the mass body 11. At this time, since the chamfer 11a is formed at the inner peripheral edges of both ends in the axial direction of the mass body 11, it is possible to prevent the elastic film portion 12c of the elastic body 12 from being damaged in the press-fitting process into the mass body 11. The elastic film portion 12c is compressed in the radial direction between the outer peripheral surface of the insertion member 13 and the inner peripheral surface 11b of the mass body 11 to compensate for a significant fitting force on the inner peripheral surface 11b of the mass body 11. The mass body 11 and the elastic bodies 12 on both axial sides thereof are firmly connected to each other.

  The dynamic damper 1 constitutes a spring-mass system in which the elastic body 12 (spring portion 12d) is a spring and the mass body 11 and the insertion member 13 are masses, and the radial resonance frequency thereof is the mass body 11. And the sum of the mass of the pair of insertion members 13 and the radial shear spring constant of the spring portion 12d of the elastic body 12 are tuned to a frequency band in which the amplitude of vibration generated in the propeller shaft 2 increases most. That is, the insertion member 13 functions as a part of the mass in the spring-mass system as well as a means for compensating for the fitting force of the elastic body 12 to the elastic film portion 12c.

  As shown in FIG. 1, the dynamic damper 1 configured as described above moves the outer diameter portion 12 a of the elastic body 12 on both axial sides of the mass body 11 to a predetermined position on the inner peripheral surface 2 a of the propeller shaft 2. It is attached by press fitting.

  Here, since the dynamic damper 1 includes the annular elastic body 12, the cylindrical insertion member 13, and the mass body 11, the propeller shaft is mounted after the dynamic damper 1 is attached to the inner periphery of the propeller shaft 2. When cleaning 2 is performed, the cleaning liquid that has entered the internal space of the dynamic damper 1 during the cleaning process is easily discharged through the inner periphery of the dynamic damper 1. Alternatively, part of the cleaning liquid is also discharged through the recess 12e formed in the outer diameter portion 12a of the elastic body 12. For this reason, it is possible to prevent the cleaning liquid from remaining in the inner circumferential space of the propeller shaft 2.

  Next, in the mounted state shown in FIG. 1, when vibration in the direction perpendicular to the axis is generated as the propeller shaft 2 rotates, the elastic body 12 (spring portion 12 d) is used as a spring, and the mass body 11 and the insertion member 13 are used as mass. Since the resonance frequency of the spring-mass system (dynamic damper 1) is tuned to a frequency band in which the amplitude of vibration of the propeller shaft 2 increases most, the dynamic damper 1 resonates in such a frequency band and its vibration waveform. By the dynamic vibration absorption action in which the phase of the input vibration is opposite to that of the input vibration, the amplitude peak of the input vibration can be reduced, and the vibration and noise of the propeller shaft 2 can be effectively reduced.

  According to the dynamic damper 1, since the spring portion 12d of the elastic body 12 is mainly subjected to shear deformation with respect to the input vibration in the direction perpendicular to the axis, the radial spring constant is lowered, and excellent in the low frequency region. The dynamic vibration absorption characteristics can be ensured.

  Further, since the integrally molded product of the elastic body 12 and the insertion member 13 is a separate member with respect to the mass body 11, for example, the dynamic vibration absorption of the dynamic damper 1 is changed in response to a change in the specification of the propeller shaft 2 to be reduced in vibration. In order to make the characteristics correspond, for example, without changing the specification of the integrally molded product of the elastic body 12 and the insertion member 13, only the mass is changed by changing the length of the mass body 11 or the like, thereby resonating the spring-mass system. The frequency can be tuned. For this reason, it is not necessary to manufacture a die for integrally molding the elastic body 12 and the insertion member 13 every time the size and shape of the mass body 11 are changed, and the cost required for tuning can be reduced.

  Moreover, since the elastic body 12 made of a rubber-like elastic material is not vulcanized and bonded to the mass body 11, the mass body 11 can be easily recycled after being discarded.

  Next, FIGS. 4 and 5 show a second embodiment of the dynamic damper for a hollow shaft according to the present invention.

  In the dynamic damper 1 according to this embodiment, the difference from the first embodiment described above is that the elastic body 12 is not formed with the elastic film portion 12c covering the outer peripheral surface of the insertion member 13, and the inner periphery of the mass body 11 is not formed. The outer peripheral surface of the insertion member 13 is metal-fitted to the surface 11b. Other parts are basically the same as those of the first embodiment.

  That is, in the second embodiment, an integrally molded product including the elastic body 12 and the insertion member 13 is manufactured, and the insertion member 13 of the integrally molded product is formed from both sides in the axial direction of the mass body 11 as shown in FIG. Can be assembled by press fitting into the inner periphery of the mass body 11 and metal fitting, and can achieve the same effect as the first embodiment.

  Further, FIGS. 6 to 8 show a third embodiment of the hollow shaft dynamic damper according to the present invention.

  The dynamic damper 1 according to this embodiment is different from the first and second embodiments described above in that the elastic body 12 and the insertion member 13 are not vulcanized and bonded, and the insertion member 13 is an elastic film in the elastic body 12. It exists in the point press-fitted in the internal peripheral surface of the part 12c. Other parts are basically the same as those of the first embodiment.

  That is, as shown in FIG. 7, the dynamic damper 1 inserts the elastic film portion 12c of the elastic body 12 from both sides in the axial direction into the inner peripheral surface 11b of the axial end portion of the mass body 11, and then inserts the insertion member 13 By press-fitting into the inner periphery of the elastic membrane portion 12c, it is assembled as shown in FIG. The elastic membrane portion 12c is compressed in the radial direction between the inner peripheral surfaces 11b of the mass body 11 by the press-fitting of the insertion member 13, and compensates for a significant fitting force on the inner peripheral surface 11b of the mass body 11. The mass body 11 and the elastic bodies 12 on both axial sides thereof are firmly connected to each other.

  The insertion member 13 is first inserted into the inner periphery of the elastic film portion 12 c of the elastic body 12 and temporarily assembled, and then the elastic film portion 12 c and the insertion member 13 are inserted into the inner peripheral surface 11 b in the axial end portion of the mass body 11. It is also possible to assemble by press-fitting at the same time.

  According to the third embodiment, in addition to realizing the same effect as the first embodiment, since the elastic body 12 and the insertion member 13 are separate, the resonance frequency of the mass change can be reduced. Tuning may be performed by changing the length or thickness of the mass body 11 or by changing the length or thickness of the insertion member 13 without changing the length or thickness of the mass body 11. Since it is easy, the degree of freedom in tuning can be improved.

  Moreover, since the elastic body 12 made of a rubber-like elastic material is not vulcanized and bonded to the mass body 11 and the insertion member 13, not only the mass body 11 but also the insertion member 13 can be easily recycled after disposal. Can do.

DESCRIPTION OF SYMBOLS 1 Dynamic damper 11 Mass body 12 Elastic body 12a Outer diameter part 12b Adhesion part 12c Elastic film part 12d Spring part 12e Recess 13 Insert member 2 Propeller shaft (hollow shaft)

Claims (3)

  A mass body loosely inserted in the inner periphery of the hollow shaft to be reduced in vibration, and a rubber-like elastic material that is disposed on both sides in the axial direction of the mass body and whose outer diameter portion is fitted on the inner peripheral surface of the hollow shaft. A hollow shaft dynamic damper, comprising: a pair of elastic bodies; and an insertion member that is inserted into an inner periphery of the mass body and couples one end of the elastic body in the axial direction to the mass body.   2. The dynamic damper for a hollow shaft according to claim 1, wherein the elastic body is integrally vulcanized and bonded to the insertion member.   The dynamic damper for a hollow shaft according to claim 1 or 2, wherein the mass body, the elastic body, and the insertion member are cylindrical or annular.

Images