JP2013217402A - Vibration-proof bush - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease a multiplication rate of a vibration-proof bush such as a suspension bush of an automobile or the like.SOLUTION: A vibration-proof bush 10 includes an inner cylinder 12 and a cylindrical rubber elastic body 14 disposed on an outer periphery of the inner cylinder 12, and is to be press-fitted to the inside of a cylindrical holder. A slit 22 extending in an axial direction is formed on an outer peripheral surface of the rubber elastic body 14.

Description

  The present invention mainly relates to an anti-vibration bush such as a suspension bush of an automobile.

  In general, an anti-vibration bush such as a suspension bush for absorbing vibrations of an engine and a vehicle body to improve riding comfort and reduce noise is used in an automobile (for example, see Patent Document 1 below).

  In such an anti-vibration bush, suppression of vibration and noise in a high frequency region around 100 Hz is required. In order to suppress noise in the high frequency range, it is effective to reduce the value of dynamic magnification (dynamic spring constant (Kd) / static spring constant (Ks)), that is, in a vibration state that transmits engine vibration. It is effective to have a small dynamic spring constant and a large static stiffness, i.e., a static spring constant, indicating the support performance of the engine and the vehicle body.

JP 2003-343625 A

  However, there is a strong demand for further improvement in riding comfort and noise reduction, and there is a demand for further reduction in dynamic magnification in the vibration-proof bushing as described above.

  The present invention has been made in view of the above points, and an object thereof is to provide an anti-vibration bush capable of reducing the dynamic magnification.

  An anti-vibration bush according to the present invention includes an inner cylinder and a cylindrical rubber elastic body provided on an outer periphery of the inner cylinder, and the anti-vibration bush is press-fitted inside a cylindrical holder. A slit extending in the axial direction is provided on the outer peripheral surface of the body.

  In the vibration-proof bushing of the present invention, three or more slits may be provided at equal intervals in the circumferential direction.

  In the vibration-isolating bush of the present invention, the rubber elastic body includes a pair of flange portions protruding radially outward at both axial end portions and a pair of circumferentially provided inner sides of the pair of flange portions. An annular recess and a contact portion sandwiched between the pair of annular recesses in an axial direction may be provided, and the slit extending in the axial direction may be provided in the contact portion. In this case, the slit provided in the contact portion may be provided. The total groove width of the slits may be 3 to 20% of the peripheral length of the contact portion.

  With the anti-vibration bush of the present invention, the dynamic magnification can be reduced, and vibration and noise in a high frequency region around 100 Hz can be reduced.

Sectional drawing which shows the attachment state of the anti-vibration bush which concerns on one Embodiment of this invention. The side view of the anti-vibration bush which concerns on one Embodiment of this invention. FIG. 3 is a cross-sectional view taken along line AA in FIG. 2. The principal part enlarged view of FIG. BB sectional drawing of FIG.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, the vibration isolating bush 10 of the present embodiment includes a metal cylindrical inner cylinder 12 and a rubber elastic body 14 vulcanized and bonded to the outer peripheral surface of the inner cylinder 12. While being press-fitted into a cylindrical holder 2 provided on the lower arm 1, the vehicle body side frame 3 is fixed to the inner cylinder 12 by bolts 4, so that the vehicle body side frame 3 is attached to a connecting portion between the lower arm 1 and the vehicle body side frame 3.

  As shown in FIGS. 2 to 4, the rubber elastic body 14 has a cylindrical shape that is shorter in the axial direction X than the inner cylinder 12 that coaxially surrounds the inner cylinder 12. The rubber elastic body 14 has a pair of flanges 16 projecting radially outward at both ends in the axial direction X, and a pair of annular recesses 18 recessed radially inward inside the pair of flanges 16. Is formed. A region sandwiched in the axial direction X by the pair of annular recesses 18 is provided with a thick contact portion 20 that protrudes radially outward from the annular recess 18.

  The pair of flanges 16 have a slightly larger outer diameter than the contact part 20, and the axial direction X of the holder 2 prevents the vibration isolating bush 10 from falling out of the holder 2 of the lower arm 1 in the attached state shown in FIG. Abuts against the end face.

  The pair of annular recesses 18 are provided along the circumferential direction, and when the contact portion 20 is press-fitted into the holder 2 of the lower arm 1, the rubber in the contact portion 20 is allowed to flow in the axial direction X to facilitate the press-fitting operation. To.

  The pair of annular recesses 18 of the rubber elastic body 14 before press-fitting has a conical inclined surface in which at least the side wall on the side of the contact portion 20 among the side walls gradually increases in diameter toward the contact portion 20. . On the other hand, the side wall of the pair of annular recesses 18 on the flange 16 side forms a vertical wall that protrudes outward in the radial direction in accordance with the end wall surface of the holder 2 of the lower arm 1 to be fitted.

  The contact portion 20 is formed such that the outer diameter of the lower arm 1 before being press-fitted into the holder 2 is larger than the inner diameter of the holder 2, and is fitted and held in the holder 2 in the attached state shown in FIG.

  A plurality of slits 22 extending along the axial direction X are provided on the outer peripheral surface of the contact portion 20 at equal intervals in the circumferential direction. In the present embodiment, six slits 22 having the same shape are axial centers. It is provided every 60 degrees around O.

  The number of slits 22 provided in the contact portion 20 is not particularly limited, but three or more slits 22 are provided in the contact portion in that the spring constant of the vibration isolating bush 10 can be made uniform around the axis O. It is preferable to provide it at equal intervals in the circumferential direction of 20.

  The slit 22 has a cross-sectional groove shape that is recessed inward in the radial direction of the contact portion 20. The slit 22 is provided over the entire axial direction of the contact portion 20, and both ends of the slit 22 open to the pair of annular recesses 18. Yes. If the contact portion 20 is provided with the slit 22, the amount of rubber disposed between the inner cylinder 12 and the holder 2 of the lower arm 1 is reduced, and the holding force of the vibration isolating bush 10 by the holder 2 may be reduced. Therefore, the holding force of the vibration isolating bush 10 by the holder 2 may be suppressed by increasing the thickness of the contact portion 20 with the same amount of rubber as the rubber reduced by providing the slit 22.

  Here, when an example of each dimension is given with reference to FIG. 4, the thickness (radial length) A of the contact portion 20 is set to 8 mm, and the groove depth B of the slit 22 is set to 1 to 2 mm. The sum of the groove widths W of the slits 22 (in this embodiment, 6 times W) can be set to 3 to 20% of the circumferential length of the contact portion 20 provided with the slits 22. If the total groove width W is less than 3% of the circumference of the contact portion 20, it is difficult to obtain the effect of reducing the dynamic magnification. If it is greater than 20%, the vibration resistance bush 10 is attached to the holder 2 of the lower arm 1 by the holder 2. Since the holding force of the vibration isolating bush 10 is reduced, the total groove width W of the slit 22 is preferably set to 3 to 20% of the circumferential length of the contact portion 20.

  In the above-described embodiment, the rubber elastic body 14 provided on the outer peripheral surface of the inner cylinder 12 is provided with the slit 22 in the contact portion 20 in the vibration isolating bush 10 including the flange portion 16, the annular recess portion 18, and the contact portion 20. However, the rubber elastic body 14 has a shape in which a slit extending along the axial direction X is provided in a portion that abuts the inner surface of the holder 2 in a mounted state of the vibration isolating bush 10 press-fitted into the holder 2 of the lower arm 1. There is no particular limitation as long as it is.

  Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.

  For the vibration isolating bush 10 of the above embodiment, the anti-vibration bushes of the example and the comparative example were made as an experiment.

  The anti-vibration bush of the embodiment is an anti-vibration bush in which the rubber elastic body includes a collar portion, an annular recess, a contact portion, and a slit. In the embodiment 1, the contact portion has three slits in the circumferential direction, etc. In the second embodiment, six slits are provided in the contact portion at equal intervals in the circumferential direction.

  In the anti-vibration bushing of the comparative example, the rubber elastic body has the same shape of the flange portion, the annular concave portion, and the contact portion as in Examples 1 and 2, but the slit is not provided in the contact portion. Only the presence or absence is different from that of the embodiment.

  About the obtained anti-vibration bush, each measuring method which measured the static spring constant and the dynamic spring constant is as follows.

Static spring constant: A static spring constant was measured by applying a weight of 4000 N to the vibration-proof bushing.

-Dynamic spring constant: The dynamic spring constant was measured by applying vibration with an amplitude of 0.05 mm and a frequency of 100 Hz to the anti-vibration bush.

  The results are as shown in Table 1. The static spring constant is the same in both the comparative example and the example, but the dynamic spring constant is an example in which a slit is provided in the contact portion compared to the comparative example in which no slit is provided in the contact portion. The constant was reduced and the multiplication factor was reduced by about 7 to 9%, and the anti-vibration performance in the high frequency range was improved.

DESCRIPTION OF SYMBOLS 1 ... Lower arm 2 ... Holder 3 ... Car body side frame 4 ... Bolt 10 ... Anti-vibration bush 12 ... Inner cylinder 14 ... Rubber elastic body 16 ... Eaves part 18 ... Ring-shaped recessed part 20 ... Contact part 22 ... Slit

Claims (4)

  An anti-vibration bush having an inner cylinder and a cylindrical rubber elastic body provided on the outer periphery of the inner cylinder and press-fitted inside the cylindrical holder extends in the axial direction on the outer peripheral surface of the rubber elastic body An anti-vibration bush characterized by being provided with a slit.   The anti-vibration bush according to claim 1, wherein three or more slits are provided at equal intervals in the circumferential direction.   The rubber elastic body includes a pair of flanges protruding radially outward at both axial ends, a pair of annular recesses provided along the circumferential direction inside the pair of flanges, and the pair of annular members The anti-vibration bush according to claim 1, further comprising a contact portion sandwiched in the axial direction by a recess, wherein the slit extending in the axial direction is provided in the contact portion.   The anti-vibration bush according to claim 3, wherein a total groove width of the slits provided in the contact portion is 3 to 20% of a circumferential length of the contact portion.

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