JP2016124422A - Center bearing support - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the centrifugal whirling of a propeller shaft caused by resonance.SOLUTION: In a center bearing support 1 in which an inner ring 12 attached to an external peripheral face of a propeller shaft 3 and holding a center bearing 4 is arranged at an internal periphery of an outer ring 11 fixed to a vehicle body side via an annular elastic support member 14 which is composed of a rubbery elastic material, and protrusively bent to a front side of a vehicle, the elastic support member 14 has resonance frequencies which are different from one another in a circumferential direction by having a plurality of relatively-thick wall parts 141 and relatively-thin wall parts 142 alternately in the circumferential direction.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a center bearing support that elastically supports a center bearing that rotatably supports a propeller shaft of an automobile on the lower side of a vehicle body.

  As a center bearing support that is attached to the lower surface of the vehicle body and elastically supports a center bearing mounted on the propeller shaft, a center bearing support as shown in FIG. 4 is conventionally known. That is, the center bearing support 100 shown in FIG. 4 has an annular elastic support member 101 bent in a substantially U-shaped convex section toward the front side of the vehicle (left side in the figure), and vulcanized and bonded integrally to the outer peripheral end thereof. The outer ring 102, the inner ring 103 integrally vulcanized and bonded to the inner peripheral portion of the elastic support member 101, and the pressing ring 104 that is fitted and integrated with the inner ring 103 and presses the outer race 111 are provided. .

  In the center bearing support 100, the outer ring 102 is fitted to the lower bracket 130 of the vehicle body, and the inner ring 103 is fitted to the outer race 111 of the center bearing 110 attached to the outer periphery of the propeller shaft 120. The center bearing 110 is elastically supported on the lower side of the vehicle body via an elastic support member 101 made of a rubber-like elastic material (rubber material or synthetic resin material having rubber-like elasticity). Vibration absorption and buffering are performed between the propeller shaft 120 side and the vehicle body side (see, for example, Patent Document 1 below).

  By the way, in this type of center bearing support 100, since the resonance frequency of a spring-mass system in which the propeller shaft 120 is a mass body and the elastic support member 101 is a spring generally exists in the vicinity of 10 to 30 Hz, For example, in the process in which the vibration frequency of the propeller shaft 120 passes through this frequency band, there is a problem that the amplitude of the swing of the propeller shaft 120 increases due to resonance.

  As a means for preventing such swinging, the elastic support member is formed in a non-circular thick wall shape, and a large number of bevels (through holes in the axial direction) are opened so that the spring of the elastic support member is circumferential. There is known a technique for suppressing swinging due to resonance by changing characteristics (see, for example, Patent Document 2 below).

  However, since the center bearing support is located on the underside of the vehicle body and is always exposed to the external environment, such as the muddy water coming in, the ones that have tickled elastic support members are immediately clogged with stepping stones and mud. If icing occurs within the edge, the durability of the elastic support member may be reduced.

JP-A-8-216710 Japanese Patent Publication No. 8-33164

  The present invention has been made in view of the above points, and a technical problem thereof is to suppress the swing of the propeller shaft due to resonance.

  As a means for effectively solving the technical problem described above, the center bearing support according to the invention of claim 1 has a center bearing attached to the outer periphery of the propeller shaft on the inner periphery of the outer ring fixed to the vehicle body side. In the center bearing support in which the inner ring to be held is provided through an annular elastic support member made of a rubber-like elastic material and bent in a convex shape toward the front side of the vehicle, the elastic support member is relatively A plurality of thin portions relative to the thick portions are alternately provided in the circumferential direction. The rubber-like elastic material is a rubber material or a synthetic resin material having rubber-like elasticity.

  In the center bearing support configured as described above, the elastic support member travels by elastically connecting the outer ring fixed to the vehicle body side and the inner ring holding the center bearing attached to the outer periphery of the propeller shaft. Vibration absorption and buffering are performed between the propeller shaft side and the vehicle body side. The elastic support member has a plurality of relative thick portions and relatively thin portions alternately in the circumferential direction, thereby having different spring constants in the circumferential direction alternately, that is, the resonance frequency is alternately in the circumferential direction. Therefore, the whirling of the propeller shaft is suppressed.

  The center bearing support according to a second aspect of the present invention is the structure according to the first aspect, wherein the thick portions are formed on the upper side and the lower side of the inner ring, and each of the thick portions, the thin portions, The boundary is composed of a stepped surface extending in the radial direction on the surface of the elastic support member facing the front side.

  In the center bearing support configured as described above, since the thick portions are located on the upper side and the lower side of the inner ring, the surface of the elastic support member facing the front side extends in the radial direction, and each thick portion and each thin portion The step surface that constitutes the boundary has a gradient between the inner diameter side and the outer diameter side, so that the muddy water that has flown from the front side to the surface of the elastic support member during traveling of the vehicle is deposited under the inner ring. It also serves as a means for guiding to flow downward.

  According to a third aspect of the present invention, there is provided a center bearing support having a dust cover which is attached to the outer peripheral surface of the propeller shaft and surrounds the outer peripheral side of the end portion of the inner ring. The front end of the elastic member is closely opposed to the surface of the thick portion of the elastic support member.

  In the center bearing support configured as described above, the dust cover constitutes a labyrinth seal between the inner ring and the elastic support member, and the gap is narrowed with the surface of the thick part of the elastic support member. In particular, it is difficult for muddy water or the like to enter between the thick wall portion located on the upper side of the inner ring and the dust cover, and the gap between the dust cover and the surface of the thin wall portion located on both sides in the horizontal direction of the inner ring. Therefore, a discharge flow path such as muddy water to the stepped surface constituting the boundary between the thick part and each thin part is secured.

  According to the center bearing support according to the present invention, the elastic support member is provided with spring constants that are alternately changed in the circumferential direction, so that swinging of the propeller shaft due to resonance can be suppressed.

It is the figure which looked at preferable embodiment of the center bearing support which concerns on this invention from the front side. FIG. 2 is a cross-sectional view in a mounted state showing a preferred embodiment of the center bearing support according to the present invention, cut along a plane passing through the line II-O-II ′ of FIG. FIG. 2 is a half cross-sectional view in a mounted state showing a preferred embodiment of the center bearing support according to the present invention, cut along a plane parallel to the axis O through line III-O in FIG. 1. FIG. 6 is a half cross-sectional view of a mounting state in which a center bearing support according to the prior art is cut along a plane passing through an axis O.

  Hereinafter, a preferred embodiment of a center bearing support according to the present invention will be described with reference to FIGS. 1, 2, and 3. 2 and 3, the left side is the front side of the vehicle, and the right side is the rear side.

  Reference numeral 1 shown in FIGS. 1 and 2 is a center bearing support, reference numeral 2 is a bracket fixed to the vehicle body side, reference numeral 3 shown in FIG. 2 is a propeller shaft, and reference numeral 4 is a center bearing.

  The propeller shaft 3 includes a propeller shaft main body 31 and a collar 32 attached to the outer peripheral surface thereof. Among these, the propeller shaft main body 31 is sequentially increased by a plurality of step portions 31a and 31b from the rear side to the front side. The collar 32 is mounted on the outer peripheral surface 31c on the rear side from the small-diameter side step portion 31a in the propeller shaft main body 31, and is symmetrical to the large-diameter side step portion 31b in the propeller shaft main body 31 on the outer peripheral surface. A stepped portion 32a is formed.

  The center bearing 4 is a ball bearing having a known structure having an outer race 41 and an inner race 42 arranged concentrically with each other, and a number of steel balls 43 rotatably held at equal intervals in the circumferential direction therebetween. The steel balls 43 are lubricated between the outer race 41 and the inner race 42 with grease (not shown).

  The center bearing support 1 is disposed on the inner peripheral surface of the support ring 21 of the bracket 2 attached to the lower side of the vehicle body, and is disposed on the inner periphery of the outer ring 11 and is attached to the propeller shaft 3. An inner ring 12 fitted to the outer race 41 of the center bearing 4, and a holding ring 13 fitted and integrated on the rear side of the inner ring 12 to hold the outer race 41 in the axial direction between the inner ring 12 and The elastic support member 14 elastically connects the outer ring 11 and the inner ring 12.

  The outer ring 11, the inner ring 12 and the holding ring 13 are made of a metal such as steel, and the elastic support member 14 is formed of a rubber-like elastic material (rubber material or a synthetic resin material having rubber-like elasticity). It has been done. The outer peripheral portion 14a of the elastic support member 14 is integrally vulcanized and bonded to the outer ring 11, and the inner peripheral portion 14b is integrally vulcanized and bonded to the outer peripheral surface of the inner ring 12, and the outer peripheral portion 14a and the inner peripheral portion 14b. A bellows-shaped bent portion 14c that is bent in a substantially U-shaped cross section convex toward the front side is formed therebetween.

  The outer race 41 of the center bearing 4 is press-fitted into the inner peripheral surface of the intermediate portion in the axial direction of the inner ring 12, and the axially intermediate fitting step portion 12 a of the inner ring 12 and the holding ring 13 from both sides in the axial direction. The inner race 32 of the center bearing 4 is fitted to the outer peripheral surface of the propeller shaft main body 31 and is sandwiched from both sides in the axial direction by the small diameter side step portion 31 a and the collar 32.

  A dust cover 15 made of metal such as steel is mounted on the rear outer peripheral surface 31d of the large-diameter side step portion 31b of the propeller shaft body 31 in the propeller shaft 3 and is located on the front side of the inner ring 12. A dust cover 16 made of metal such as steel is mounted on the front side outer peripheral surface 32b of the step portion 32a of the collar 32 in the shaft 3 and is located on the rear side of the press ring 13.

  Among these, the front dust cover 15 has a cover main body portion 15a extending in a cylindrical shape so as to surround the outer peripheral side of the front side end portion 12b of the inner ring 12 from the fitting portion with the propeller shaft main body 31. The front-side end portion 12 b of the inner ring 12 is bent toward the inner diameter side and is in close proximity to the inner diameter portion of the dust cover 15 or the outer peripheral surface of the propeller shaft main body 31. Therefore, a labyrinth seal LS1 having a zigzag gap is formed between the end 12b of the inner ring 12 and the inner peripheral portion 14b of the elastic support member 14 and the outer peripheral surface of the dust cover 15 and the propeller shaft body 31. Has been.

  Further, the dust cover 16 on the rear side has a cover main body portion 16a that extends in a cylindrical shape from the fitting portion with the collar 32 toward the inner peripheral space of the fitting portion 13b of the holding ring 13 to the inner ring 12. The inner diameter portion of the retaining ring 13 extends from the contact portion of the center bearing 4 with the outer race 41 to the rear side of the center bearing 4, and the inner diameter end portion 13 a is bent toward the inner diameter side, It is in close proximity to the surface. For this reason, a labyrinth seal LS <b> 2 is formed between the fitting portion 13 b and the inner diameter end portion 13 a of the press ring 13 and the outer peripheral surfaces of the dust cover 16 and the collar 32.

  Two relatively thick portions 141 and two relatively thin portions 142 are alternately formed in the circumferential direction on the inner peripheral portion 14 b of the elastic support member 14. Specifically, the relative thick portion 141 of the inner peripheral portion 14b of the elastic support member 14 is located above and below the inner ring 12 as shown in FIG. , Located on both sides of the inner ring 12 in the horizontal direction.

  The thick portion 141 and the thin portion 142 are formed with a difference in height (thickness) toward the front side of the inner peripheral portion 14b of the elastic support member 14, and each thick portion 141 and The boundary with each thin portion 142 is formed of a step surface 143 extending in the radial direction on the front-facing surface of the inner peripheral portion 14 b of the elastic support member 14. The step surface 143 also serves as a means for guiding the muddy water that has flown from the front side to the surface of the elastic support member 14 to flow down. As shown in FIGS. 2 and 3, the front-facing surfaces of the thick portion 141 and the thin portion 142 are small diameter cylindrical portions between the fitting step portion 12 a and the front side end portion 12 b in the inner ring 12. From the outer peripheral surface of 12c, it has stood up in the radial direction so as to form a plane substantially orthogonal to the axis O.

  As described above, since the thick portion 141 and the thin portion 142 are formed with a difference in height (thickness) toward the front side in the inner peripheral portion 14b of the elastic support member 14, FIG. As shown in FIG. 5, the length of the bellows-shaped bent portion 14c is relatively shorter by ΔL in the portion located on the outer diameter side of the thick portion 141 than in the portion located on the outer diameter side of the thin portion 142. Yes. For this reason, the elastic support member 14 has a relatively high spring constant in the vertical direction in which the thick portion 141 is formed, and has a relatively low spring constant in the horizontal direction in which the thin portion 142 is formed. That is, the high spring region and the low spring region are distributed alternately in the circumferential direction.

  A pair of drain grooves 144 extending obliquely downward (in the radial direction) on the lower side of the inner ring 12 is formed on the front surface of the bellows-shaped bent portion 14c. Each drainage groove 144 is continuous with a step surface 143 (lower step surface 143L in FIG. 1) between the lower thick portion 141 and the thin portions 142 on both sides thereof. Further, the drainage groove 144 is formed to be wide on the inner diameter side (upper side) and narrower on the outer diameter side (lower side).

  The center bearing support 1 having the above configuration supports the center bearing 4 elastically and rotatably on the bracket 2 on the vehicle body side, and when vibration occurs in the rotating propeller shaft 3, the inner ring 12 and the outer ring 11 are supported. The bellows-shaped bent portion 14c of the elastic support member 14 is repeatedly bent and stretched in association with the relative eccentric motion, effectively isolating vibration transmission to the vehicle body side.

  Here, in the process of increasing the vibration frequency of the propeller shaft 3, for example, when the vehicle starts, this vibration frequency is a resonance of a spring-mass system in which the propeller shaft 3 is a mass body and the elastic support member 14 is a spring. It will pass through the frequency band. However, the center bearing support 1 configured as described above has a relatively thick portion 141 positioned above and below the inner ring 12 on the inner peripheral portion 14b of the elastic support member 14 and relative positions positioned on both sides of the inner ring 12 in the horizontal direction. Since the high spring constant and the low spring constant are set alternately in the circumferential direction by having the thin wall portion 142, the resonance frequency changes alternately in the circumferential direction even if the propeller shaft 3 tries to swing. This effectively suppresses the swing of the propeller shaft 3.

  Here, muddy water or the like flying from the front side is difficult to enter the center bearing 4 by the labyrinth seal LS1 bent in a zigzag manner. In particular, since the gap δ1 between the thick wall portion 141 located above and below the inner ring 12 and the cover main body portion 15a of the dust cover 15 is narrow, it is extremely difficult for muddy water or the like to enter here. On the other hand, muddy water or the like from the rear side is difficult to enter the center bearing 4 by the similar labyrinth seal LS2. In addition, since the labyrinth seals LS1 and LS2 are non-contact seals, fuel consumption is not deteriorated due to sliding resistance as in the case where contact-type seals are provided.

  Further, since the gap δ2 between the thin wall portion 142 located on both sides in the horizontal direction of the inner ring 12 and the cover body portion 15a of the dust cover 15 is relatively wide, it jumps here and adheres to the surface of the thin wall portion 142. The muddy water and the like that flows down easily. Then, the step surface 143 (the lower step surface 143L in FIG. 1) constituting the boundary between the thick portion 141 located on the lower side of the inner ring 12 and the thin portions 142 on both sides thereof is from the inner diameter side to the outer diameter side. Since the drainage groove 144 having a slope that decreases toward the surface and further extending with a continuous slope is formed on the surface of the bellows-shaped bent portion 14c, the muddy water that has flowed down the surface of the thin-walled portion 142 is further stepped. Since dripping through the drainage groove 144 from the surface 143L, intrusion of muddy water into the center bearing 4 side is effectively prevented. In addition, since the drainage groove 144 is narrower on the outer diameter side (lower side), the intrusion of muddy water from below due to the splashing of muddy water from the road surface and the like when the vehicle is running is effectively suppressed.

  Further, the step surface 143 between the thick portion 141 and the thin portion 142 and the drainage groove 144 continuous therewith can be used as a circumferential positioning means when the center bearing support 1 is mounted on the bracket 2. . In this case, specifically, for example, by providing a protrusion on the mounting jig and fitting it into the stepped surface 143 or the drainage groove 144, the drainage groove 144 is surely located below the inner ring 12. Thus, positioning in the circumferential direction can be performed.

DESCRIPTION OF SYMBOLS 1 Center bearing support 11 Outer ring 12 Inner ring 13 Holding ring 14 Elastic support member 14a Outer peripheral part 14b Inner peripheral part 141 Thick part 142 Thin part 143 Step surface 144 Drain groove 14c Bellows bending part 15, 16 Dust cover 3 Propeller shaft 4 Center bearing

Claims (3)

  An inner ring that holds a center bearing attached to the outer periphery of the propeller shaft is formed of a rubber-like elastic material and is bent in a convex shape toward the front side of the vehicle. A center bearing support provided via an elastic support member, wherein the elastic support member has a plurality of relative thick portions and relatively thin portions alternately in a circumferential direction.   Stepped surfaces having thick portions formed on the upper and lower sides of the inner ring, and the boundary between each thick portion and each thin portion extending in the radial direction on the surface of the elastic support member facing the front side The center bearing support according to claim 1, comprising:   It has a dust cover that is attached to the outer peripheral surface of the propeller shaft and surrounds the outer peripheral side of the end portion of the inner ring, and the tip of the dust cover is closely opposed to the surface of the thick portion of the elastic support member. The center bearing support according to claim 2.

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