JP2011185411A - Mounting structure for dynamic damper of drive shaft - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide mounting structure for a dynamic damper of a drive shaft, preventing runout of a drive shaft even if a drive shaft is broken. <P>SOLUTION: In the dynamic damper mounted at an intermediate part in a longitudinal direction of the drive shaft 1, a weakest part 11 is formed at the intermediate part in the longitudinal direction of the drive shaft 1. A mass part 21 is formed of rigid metallic material and covers over a predetermined axial region around the weakest part as a center, so that the mass part 21 can restrict the runout of the broken part when the drive shaft 1 is broken at the weakest part 11. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a structure for mounting a dynamic damper to a dynamic damper.

  Conventionally, there has been known a vehicle in which a drive shaft is provided between a differential gear of a transmission and a drive wheel, and a driving force is transmitted to the drive wheel by the drive shaft. In order to suppress the noise and vibration associated with the rotation of the drive shaft, there is a type in which a dynamic damper is provided at an intermediate portion in the longitudinal direction of the drive shaft.

  Generally, a dynamic damper is formed with a cylindrical mass portion having a diameter larger than the outer diameter of the drive shaft by a predetermined amount, and elastic support portions on both axial sides of the mass portion, and the elastic support portion is fixed to the drive shaft. Of structure.

  In conventional drive shafts, the parts located in the joint boots at both ends in the axial direction are often narrow, and if the drive shaft breaks due to abnormal load on the drive wheels, it can break at this joint part High nature. In this case, if the vehicle speed is high and the rotation speed of the shaft is high, the joint boot may be torn and the shaft may swing and damage peripheral components (such as a brake hose). On the other hand, when a drive shaft whose both ends are not the weakest is used, it is unclear at which part the drive shaft breaks. Therefore, as described above, the shaft may swing around at the broken portion, and there is a possibility that peripheral parts may be damaged.

  In Patent Document 1, an annular groove is formed in the middle portion of the drive shaft in the longitudinal direction, an annular protrusion is formed on the inner peripheral surface of the central portion of the symmetrical dynamic damper, and this annular protrusion is formed into an annular recess of the drive shaft. The thing which fits into the groove | channel and made the fastening band unnecessary is disclosed.

  In Patent Document 2, a small-diameter portion having a predetermined length is formed in the middle portion in the longitudinal direction of the drive shaft, a dynamic damper is mounted across the small-diameter portion, and both axial end portions of the dynamic damper are connected to the drive shaft by fastening bands. A structure that is fastened to the outer peripheral portion is disclosed.

  In Patent Document 1, when it is assumed that the annular groove of the drive shaft is the weakest part, when the drive shaft breaks at the annular groove, the broken part is easily removed from the dynamic damper. For this reason, the dynamic damper cannot hold the broken portion of the drive shaft and cannot prevent the drive shaft from swinging.

  In Patent Document 2, even if it is assumed that the small-diameter portion is the weakest portion, the small-diameter portion has a predetermined length, so it is unclear at which part of the small-diameter portion the fracture occurs. Although the outer periphery of the small diameter portion is covered with a dynamic damper, when the end portion of the small diameter portion is broken, the broken portion is detached from the mass portion and can be bent.

Japanese Patent Laid-Open No. 10-132027 JP-A-8-28627

  An object of the present invention is to provide a drive shaft dynamic damper mounting structure capable of preventing the drive shaft from swinging even when the drive shaft is broken.

  In order to achieve the above object, the present invention integrally includes a cylindrical mass portion covering the outer periphery of the drive shaft and elastic support portions formed on both sides in the axial direction of the mass portion, and the elastic support portion is provided. In the mounting structure of the dynamic damper attached to the middle of the drive shaft in the longitudinal direction by supporting the drive shaft, the weakest part of the drive shaft is formed at the middle of the drive shaft in the longitudinal direction, and the mass The mass portion is formed of a metal material having rigidity, and when the drive shaft is broken at the weakest portion, the mass portion is the weakest so that the mass portion can regulate the swing of the broken portion of the drive shaft. The drive shaft dynamic damper is characterized in that the outer periphery of the drive shaft is covered over a predetermined axial direction centered on the portion. To provide a path mounting structure.

  In the present invention, the weakest portion is formed in advance in the dynamic damper mounting portion of the drive shaft, and even if the drive shaft breaks, it is set so that it always breaks at the weakest portion. The mass portion of the dynamic damper is formed of a metal material having rigidity, and this mass portion covers a predetermined axial region centering on the weakest portion of the drive shaft. Therefore, when the drive shaft is broken at the weakest portion, the mass portion can regulate the swing of the broken portion. Relative rotation occurs between the broken one drive shaft portion and the other drive shaft portion, but the relative rotation can be allowed by sliding of the elastic support portion of the dynamic damper. As a result, it is possible to prevent damage to the peripheral parts due to the swinging of the broken part. Since the drive shaft is broken and the driving force is not transmitted, it can be immediately known that the drive shaft is broken.

  The elastic support portions formed at both ends of the dynamic damper are supported by the drive shaft. When this support portion is displaced in the axial direction with respect to the drive shaft, the broken portion of the drive shaft is detached from the mass portion of the dynamic damper. there is a possibility. Therefore, circumferential grooves or circumferential ribs are formed on both sides of the weakest part of the drive shaft, the elastic support part is fitted into the circumferential grooves or circumferential ribs, and the outer periphery is fastened to the fastening band. It is good to conclude with. When the drive shaft is broken, a force in the pulling direction acts on the dynamic damper on both sides of the broken portion. On the other hand, since the elastic support portion of the dynamic damper is fitted to the circumferential groove or the circumferential rib of the drive shaft and fastened by the fastening band, the dynamic damper is not detached from the circumferential groove or the circumferential rib. The mass portion can always cover the fracture portion. As a result, it is possible to more effectively prevent the broken portion from swinging.

  As described above, according to the dynamic damper mounting structure of the present invention, when the drive shaft breaks at the weakest portion, the mass portion of the dynamic damper having rigidity extends over a predetermined axial region centering on the weakest portion. Therefore, the mass portion can regulate the swing of the broken portion. As a result, it is possible to eliminate the damage to the peripheral parts due to the swinging of the broken part.

It is a general view of an example of the drive shaft which attached the dynamic damper concerning the present invention. It is an expanded sectional view of the principal part of the drive shaft shown in FIG. FIG. 3 is an enlarged cross-sectional view of a main part of the drive shaft shown in FIG. 2 in a broken state. It is a principal part expanded sectional view of 2nd Example of a drive shaft.

  FIG. 1 shows an embodiment of a drive shaft according to the present invention. The drive shaft 1 is used for an independent suspension type front wheel drive vehicle. One end shaft portion 2 (for example, the left shaft portion) is connected to a differential gear, and the other end shaft portion 3 (for example, the right shaft portion) is a drive wheel. Connected to (front wheel). The one end shaft portion 2 is connected to the drive shaft 1 via a universal joint 4 so that the angle can be changed. The other end shaft portion 3 is also connected via a universal joint 5 so that the angle can be changed. The universal joints 4 and 5 are covered with boots 6 and 7, respectively.

  As shown in FIG. 2, a constricted portion 11 is formed at an intermediate portion in the length direction of the drive shaft 1, and the constricted portion 11 is the weakest portion in the entire drive shaft. The constricted portion 11 is configured by forming an outer peripheral groove on the drive shaft 1, and the axial dimension S thereof is set to be short (for example, 5 cm or less). Therefore, in the unlikely event that the drive shaft 1 breaks, the constricted portion 11 is set to be surely broken. Circumferential groove portions 12 and 13 are formed on both sides of the constricted portion 11. The circumferential groove portions 12 and 13 are configured between two pairs of ribs 12a, 12b, 13a, and 13b formed on the outer periphery of the drive shaft 1.

  A dynamic damper 20 is attached to the middle portion in the length direction of the drive shaft 1 so as to cover the outer periphery of the constricted portion 11. The dynamic damper 20 includes a cylindrical mass portion 21 that covers the outer periphery of the drive shaft 1 and a rubber-like elastic body 22 that covers the periphery of the mass portion 21. The mass portion 21 is formed in a cylindrical shape by a metal material (for example, iron) having rigidity and weight, and has a function of suppressing noise and vibration of the drive shaft 1 during normal running and suppressing swinging when the drive shaft 1 is broken. Have. The mass portion 21 does not need to be formed of a cylindrical part. For example, the mass portion 21 may be formed in a substantially cylindrical shape by bending a flat metal plate into a cylindrical shape. Therefore, you may have a slit in an axial direction. The inner diameter of the mass portion 21 is larger than the outer diameter of the drive shaft 1, and the axial dimension L of the mass portion 21 is set sufficiently longer than the axial dimension S of the constricted portion 11. In this embodiment, the inner peripheral side of the mass portion 21 is covered with a portion 22c of the rubber-like elastic body 22, and a predetermined gap δ is formed between the inner peripheral surface of the portion 22c and the outer peripheral surface of the drive shaft 1. Has been. The gap δ and the dimension L are set to dimensions such that when the drive shaft 1 is broken at the constricted portion 11, the broken portion is not detached from the mass portion 21, and the mass portion 21 can regulate the swing of the broken portion. ing. Note that the mass portion 21 may be exposed on the inner surface without the inner peripheral surface of the mass portion 21 being covered by the portion 22c of the rubber-like elastic body 22.

  Elastic support portions 22 a and 22 b are integrally formed by elastic bodies 22 on both axial sides of the mass portion 21. The elastic support portions 22a and 22b are respectively fitted into the circumferential groove portions 12 and 13 of the drive shaft 1, and the elastic support portions 22a and 22b are driven by fastening the outer peripheries of the elastic support portions 22a and 22b with fastening bands 25 and 26. The shaft 1 is attached so as not to move in the axial direction.

  Here, the function of the dynamic damper 20 when the drive shaft 1 is broken will be described with reference to FIG. If an abnormal load is applied to the drive wheels during traveling, the drive shaft 1 may break. In that case, as shown in FIG. 3, the drive shaft 1 always breaks at the constricted portion 11 which is the weakest portion. One side of the drive shaft 1 that is broken is driven by a drive source, but the other side is a driven side, so that relative rotation occurs. At this time, one of the elastic support portions 22a and 22b attached to the drive shaft 1 slides with respect to the drive shaft 1, so that the drive shaft 1 is idled at the portion of the dynamic damper 20. When the drive shaft 1 is broken, a force in the pulling direction acts on the dynamic damper 20 on both sides of the broken portion, but the elastic support portions 22a and 22b of the dynamic damper 20 are fitted to the circumferential groove portions 12 and 13, Since the outer periphery is fastened by the fastening bands 25 and 26, the elastic support portions 22 a and 22 b do not come off from the circumferential groove portions 12 and 13. The broken drive shaft 1 may be bent at the broken portion, but the bending of the predetermined angle or more is restricted by the mass portion 21 of the rigid dynamic damper 20, so that the drive shaft 1 does not swing. As a result, it is possible to prevent damage to peripheral parts due to the swinging of the drive shaft 1 at the time of breakage, and secondary defects can be eliminated.

  FIG. 4 shows a second embodiment of the present invention. The same parts as those in the first embodiment (FIG. 2) are denoted by the same reference numerals, and redundant description is omitted. In this embodiment, circumferential ribs 14 and 15 are provided on both sides of the weakest portion 11, and elastic support portions 22a and 22b of the dynamic damper 20 are fitted outside the ribs 14 and 15, so that the elastic support portions 22a and 22b are fitted. Are fastened with fastening bands 25, 26. Also in this case, it is possible to prevent the elastic support portions 22a and 22b from being detached from the circumferential ribs 14 and 15 when the drive shaft 1 is broken.

  Although the circumferential groove portions 12 and 13 and the circumferential ribs 14 and 15 are provided in order to restrict the axial displacement of the elastic support portions 22a and 22b at the time of fracture, a step portion is formed instead of the circumferential grooves and ribs. Alternatively, the elastic support portion may be bonded and fixed to the drive shaft by vulcanization bonding or the like.

  The weakest portion 11 of the drive shaft 1 is not limited to the constricted portion in which the outer peripheral groove is formed as in the embodiment. For example, a notch or a concave portion is formed in a part of the circumferential direction, or a hole penetrating in the radial direction. Etc. may be formed.

1 Drive shaft 2, 3 Shaft part 4, 5 Universal joint 11 Constricted part (weakest part)
12, 13 Circumferential groove portions 14, 15 Circumferential rib 20 Dynamic damper 21 Mass portion 22 Rubber elastic bodies 22a, 22b Elastic support portions 25, 26 Fastening band

Claims (1)

A cylindrical mass portion that covers the outer periphery of the drive shaft and elastic support portions formed on both sides in the axial direction of the mass portion are integrally provided, and the elastic support portion is supported by the drive shaft, thereby In the mounting structure of the dynamic damper attached to the middle part in the length direction,
The weakest part of the drive shaft is formed in the middle part in the longitudinal direction of the drive shaft,
The mass portion is formed of a rigid metal material,
When the drive shaft breaks at the weakest portion, the mass portion extends over a predetermined axial region around the weakest portion so that the mass portion can regulate the swing of the broken portion of the drive shaft. The drive shaft dynamic damper mounting structure is characterized by covering the outer periphery of the drive shaft.

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