JP2012140974A - Cylindrical vibration damping device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cylindrical vibration damping device having a novel structure that satisfies both axial load bearing and lateral vibration isolation and sufficiently secures a linear region of spring characteristics in the axial lateral directions.SOLUTION: In the cylindrical vibration damping device 10, an inner axis member 12 and an outer cylindrical member 14 are coupled with a body rubber elastic body 16. A plurality of protrusions 52 are axially disposed separately from each other on the outer peripheral surface of the inner axis member 12 fixed to the body rubber elastic body 16. In axial projection, all of tip ends of the protrusions 52 has a height which does not reach a fixing surface of the body rubber elastic body 16 in the outer cylindrical member 14, and the protrusions 52 are buried in the body rubber elastic body 16. In addition, the thickness of the body rubber elastic body 16 between facing surfaces of the inner axis member 12 and the outer cylindrical member 14 is larger in a portion where the protrusion 52 is not formed than a portion where the protrusion 52 is formed.

Description

  The present invention relates to a cylindrical vibration isolator suitably used for, for example, a suspension member mount of an automobile.

  2. Description of the Related Art Conventionally, a cylindrical vibration isolator has been known as a type of a vibration isolator that is interposed between members constituting a vibration transmission system and that mutually antivibrates and connects these members. The cylindrical vibration isolator has a structure in which an inner shaft member and an outer cylinder member are elastically connected by a main rubber elastic body. For example, when used as a suspension member mount, the inner shaft member is attached to a vehicle body. At the same time, the outer cylinder member is attached to the suspension member (subframe), so that the suspension member is supported in a vibration-proof manner with respect to the vehicle body.

  By the way, in a cylindrical vibration isolator, an excellent load resistance may be required in the axial direction, and in that case, it is desirable to set a large spring constant in the axial direction. Therefore, in Japanese Utility Model Laid-Open No. 4-113343 (Patent Document 1) and the like, a protrusion projecting from the inner shaft member toward the outer peripheral side is provided in order to ensure load resistance in the axial direction.

  However, when such a protrusion is provided, the thickness dimension in the direction perpendicular to the axis of the main rubber elastic body is reduced at the portion where the protrusion is formed. In some cases, the constant becomes large and it is difficult to realize the required spring characteristics.

  In view of this, Japanese Patent Application Laid-Open No. 8-233007 (Patent Document 2) proposes a structure that can suppress the spring constant in the direction perpendicular to the axis while increasing the spring constant in the axial direction. That is, in Patent Document 2, the axial end portion of the outer cylindrical member is extended to the inner peripheral side, and is arranged so as to overlap with the projection provided on the inner shaft member in the axial projection. The main rubber elastic body is compressed between the axial directions of the outer cylinder member, and the protruding front end surface of the protrusion is reduced so that the protrusion between the protrusion and the outer cylinder member is perpendicular to the axial direction of the main rubber elastic body. The part to be compressed is limited.

  However, in such a cylindrical vibration isolator described in Patent Document 2, a part of the main rubber elastic body is sandwiched between the axial directions of the inner shaft member and the outer cylinder member, and the compression spring component is predominantly used. Since the spring constant in the axial direction is increased by this, there is a case where non-linear load-displacement characteristics become a problem in the axial direction. In other words, even if the relative displacement amount between the inner shaft member and the outer cylinder member is within the normal use range, the axial spring constant changes non-linearly with respect to the displacement amount and increases remarkably. There was a risk that the vibration effect would not be fully exhibited.

Japanese Utility Model Publication No. 4-113343 JP-A-8-233007

  The present invention has been made in the background of the above-mentioned circumstances, and the problem to be solved is to achieve a high level of both load resistance in the axial direction and vibration insulation in the direction perpendicular to the axis. A cylindrical vibration isolator having a novel structure capable of sufficiently securing a linear region of spring characteristics in the direction and preventing a rapid change in the spring constant with respect to the displacement amount of the inner shaft member and the outer cylindrical member in the axial direction. There is to do.

  That is, the first aspect of the present invention is a cylindrical vibration damping device in which an outer cylindrical member is disposed on the outer peripheral side of an inner shaft member, and the inner shaft member and the outer cylindrical member are connected by a main rubber elastic body. A plurality of protrusions are provided on the outer peripheral surface of the inner shaft member fixed to the main rubber elastic body so as to be spaced apart from each other in the axial direction, and the tip ends of the protrusions are projected in the axial direction. The outer cylinder member has a protruding height that does not reach the fixing surface of the main rubber elastic body, and the protrusions are embedded in the main rubber elastic body, and the inner shaft member and the outer cylinder member are opposed to each other. The thickness dimension of the main rubber elastic body between the surfaces is larger at the portion where the protrusion is not formed than at the portion where the protrusion is formed.

  According to the cylindrical vibration isolator having the structure according to this aspect, since the protrusion is provided on the outer peripheral surface of the inner shaft member, the spring constant in the axial direction is set large, and The load resistance is improved. As a result, even when a static load input in the axial direction is large, occurrence of cracks or the like in the main rubber elastic body is prevented, and sufficient durability is ensured. In particular, since the protrusion is embedded in the main rubber elastic body, it is possible to set a larger spring constant in the axial direction, and a cylindrical vibration isolator having excellent load resistance in the axial direction. Can be realized.

  In addition, the protrusion is formed with a protruding height at which the tip does not reach the fixing surface of the main rubber elastic body in the outer cylindrical member in the axial projection. Therefore, it is possible to prevent the main rubber elastic body from being sandwiched between the inner shaft member and the outer cylinder member and compressed when the vibration is input in the axial direction. As a result, a larger linear region is secured in the axial spring characteristics (load-displacement characteristics), so that a large static load is input in the axial direction or a large amplitude vibration is input in the axial direction. Even in this case, the rapid increase of the axial spring is avoided, and an effective anti-vibration effect is exhibited.

  The reason why a large linear region is ensured is that the main rubber elastic body is thick at the portion where the protrusion is axially removed, so that the substantial free length of the main rubber elastic body is increased. It is also possible that Further, in a state where the relative displacement amount between the inner shaft member and the outer cylinder member is small, the spring of the thin portion of the main rubber elastic body provided at the projecting portion acts predominantly, while the inner shaft member and the outer cylinder member act. When the relative displacement amount of the cylindrical member increases, the influence of the spring of the thick-walled portion of the main rubber elastic body provided at the portion where the protrusion is removed increases, and the initial hard spring characteristics and a sufficiently large linear region are obtained. It is also conceivable that both securing can be achieved.

  A plurality of protrusions are formed apart from each other in the axial direction, and the main rubber elastic body is thick between the protrusions. In short, in the main rubber elastic body, the thinned portion by the formation of the protrusion is made relatively small, and the spring constant in the direction perpendicular to the axis due to the formation of the protrusion is suppressed. As a result, a vibration isolation effect effective against vibration in a direction perpendicular to the axis is exhibited, and the intended vibration isolation effect can be obtained.

  Further, since the main rubber elastic body is thickened at the portion where the protrusion is removed, when vibration is input in a direction perpendicular to the axis from which the protrusion protrudes, the protrusion and the outer cylinder member in the main rubber elastic body. Since the portion compressed between the two escapes to the thick portion off the protrusion, deformation of the main rubber elastic body is sufficiently allowed. As a result, an increase in the spring constant in the direction perpendicular to the axis is suppressed, and a vibration isolation effect for vibration input in the direction perpendicular to the axis can be effectively obtained.

  According to a second aspect of the present invention, in the cylindrical vibration isolator described in the first aspect, the side surface of the recess formed between the axial directions of the plurality of protrusions is an inclined surface, The recess gradually widens in the axial direction toward the opening side.

  According to the second aspect, since the recess gradually expands in the axial direction toward the opening side, the deformation restraining action by the protrusion on the thick portion of the main rubber elastic body that has entered the recess. Is suppressed. As a result, when the inner shaft member and the outer cylinder member are relatively displaced, a linear region of the spring characteristics is sufficiently secured, and a sudden increase in the spring constant is avoided, so that the desired vibration isolation effect is effectively obtained. be able to.

  According to a third aspect of the present invention, in the cylindrical vibration isolator described in the first or second aspect, a protruding tip surface of the protrusion is a convex curved surface.

  According to the third aspect, the projecting tip surface of the projecting portion is formed of a smooth curved surface that is convex toward the outer peripheral side, so that stress is concentrated in the fixing portion of the main rubber elastic body to the projecting portion. The occurrence of cracks and the like due to an adverse effect is prevented, and durability is improved.

  According to a fourth aspect of the present invention, in the cylindrical vibration damping device described in any one of the first to third aspects, the volume of the recess formed between the axial directions of the plurality of protrusions is It is set to 10% or more and 50% or less of the volume of the main rubber elastic body.

  According to the fourth aspect, since the volume of the recess is set to 10% or more with respect to the volume of the main rubber elastic body, the rubber volume of the main rubber elastic body is sufficiently secured at the formation portion of the recess. As a result, the securing of the linear region of the spring characteristics and the low spring in the direction perpendicular to the axis are both effectively realized. Further, since the volume of the recess is set to 50% or less with respect to the volume of the main rubber elastic body, the main rubber elastic body is arranged with a sufficient thickness between the opposing surfaces of the protrusion and the outer cylinder member. Thus, sufficient durability against the load input in the axial direction is realized.

  According to a fifth aspect of the present invention, in the cylindrical vibration damping device described in any one of the first to fourth aspects, a pair of straight portions has a diameter of the inner shaft member on the main rubber elastic body. It is formed sandwiched in the direction.

  According to the fifth aspect, at the time of vibration input between the inner shaft member and the outer cylindrical member, the main rubber elastic body is allowed to bulge out to the pair of straight portions, so that it becomes easier to deform. As a result, a larger linear region of the spring characteristics is secured, and the spring constant in the direction perpendicular to the axis can be set smaller.

  Moreover, since the spring constant in the direction perpendicular to the axis can be set small by providing a thick portion of the main rubber elastic body between the plurality of protrusions, the axis perpendicular to the axis is relatively small. Anti-vibration characteristics required in the direction can be realized. As a result, the spring constant in the axial direction can be kept large even when the straight portion is formed, and sufficient load resistance can be ensured.

  According to a sixth aspect of the present invention, in the cylindrical vibration isolator described in any one of the first to fifth aspects, the plurality of protrusions are annular and extend in the circumferential direction. The recess formed between the axial directions of the protrusions is formed into a groove shape extending continuously over the entire circumference.

  According to the 6th aspect, it can avoid that the relative direction in the circumferential direction of an inner shaft member and an outer cylinder member is limited by formation of a protrusion or a recess. Therefore, for example, the setting operation of the inner shaft member and the outer cylinder member with respect to the vulcanization mold of the main rubber elastic body can be facilitated, and the occurrence of defects due to misdirection can be avoided.

  According to a seventh aspect of the present invention, in the cylindrical vibration damping device described in any one of the first to sixth aspects, a separate cylindrical member is externally fitted to the inner shaft member. The plurality of protrusions are formed on the cylindrical member.

  According to the seventh aspect, it is possible to simplify the shape of the inner shaft member and to facilitate manufacture as compared with the case where the protrusion is directly formed on the inner shaft member. In addition, if the cylindrical member is formed of synthetic resin or the like, it is possible to easily form a protrusion having an arbitrary shape, and therefore it is possible to easily provide a protrusion according to the required spring characteristics and the like.

  According to the present invention, by forming the protrusions on the outer peripheral surface of the inner shaft member, the load resistance in the axial direction is sufficiently ensured, and a plurality of protrusions are formed. Since the main rubber elastic body is thick, the spring constant in the direction perpendicular to the axis is suppressed. Further, the main rubber elastic body is thickened at the portion where the protrusion is removed, and a large linear region of the spring characteristic is secured, so that excellent vibration isolation performance can be obtained.

It is a longitudinal cross-sectional view which shows the vehicle mounting state of the suspension member mount as a 1st Embodiment of this invention, Comprising: The figure equivalent to the II cross section of FIG. FIG. 3 is a front view of the suspension member mount shown in FIG. 1. FIG. 3 is a plan view of the suspension member mount shown in FIG. 2. FIG. 3 is a bottom view of the suspension member mount shown in FIG. 2. VV sectional drawing of FIG. VI-VI sectional drawing of FIG. The longitudinal cross-sectional view which shows the vehicle mounting state of the suspension member mount as the 2nd Embodiment of this invention. FIG. 8 is a cross-sectional view of the suspension member mount shown in FIG. 7 and corresponds to a VIII-VIII cross section of FIG. 7. The graph which shows the load-displacement characteristic in the axial direction of the suspension member mount shown by FIG. The longitudinal cross-sectional view which shows the vehicle mounting state of the suspension member mount as the 3rd Embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 shows a suspension member mount 10 as a first embodiment of a cylindrical vibration isolator according to the present invention in a mounted state on a vehicle. As shown in FIGS. 2 to 6, the suspension member mount 10 has a structure in which an inner shaft member 12 and an outer cylinder member 14 disposed on the outer peripheral side thereof are elastically connected by a main rubber elastic body 16. The inner shaft member 12 is attached to the vehicle body 18 side, and the outer cylinder member 14 is attached to the suspension member 20 side, so that the inner shaft member 12 is attached to the vehicle. In the following description, the up and down direction refers to the up and down direction in FIG. 1 that is a substantially vertical direction in the vehicle mounted state and is the axial direction of the suspension member mount 10.

  More specifically, the inner shaft member 12 is a thick, small-diameter, generally cylindrical shape, linearly extending in the vertical direction, and is a highly rigid member formed of iron or an aluminum alloy. The inner shaft member 12 is fixed to the vehicle body 18 by mounting bolts 22 and mounting nuts 24.

  The outer cylinder member 14 has a thin cylindrical shape with a large diameter, and is a highly rigid member similar to the inner shaft member 12. Further, the lower end portion of the outer cylinder member 14 is bent and extends radially outward, and an annular contact flange portion 26 is formed. The outer cylinder member 14 is fitted in the mounting recess 27 of the suspension member 20.

  The outer cylinder member 14 is extrapolated to the inner shaft member 12 and is disposed on the outer peripheral side of the inner shaft member 12 with a predetermined distance therebetween. The radial direction of the inner shaft member 12 and the outer cylinder member 14 A main rubber elastic body 16 is disposed therebetween. The main rubber elastic body 16 has a thick, large-diameter, generally cylindrical shape, and its inner peripheral surface is vulcanized and bonded to the inner shaft member 12 and a cylindrical member 48 described later, and the outer peripheral surface is an outer cylinder. The member 14 is vulcanized and bonded. The main rubber elastic body 16 of the present embodiment is formed as an integrally vulcanized molded product including the inner shaft member 12, a cylindrical member 48 described later, and the outer cylindrical member 14.

  Further, the main rubber elastic body 16 is formed with a pair of straight portions 28 and 28 which are opposed to each other in one radial direction (left and right direction in FIG. 6) with the inner shaft member 12 interposed therebetween. The straight portion 28 is formed so as to penetrate the radial intermediate portion of the main rubber elastic body 16 in the axial direction, and extends in the circumferential direction with a predetermined length of slightly less than a half circumference. Further, the width of the straight portion 28 in the radial direction gradually decreases toward the center in the axial direction.

  Furthermore, a pair of lower stopper rubbers 30 extending in the circumferential direction with a length of a little less than a half in the circumferential direction are integrally formed on the main rubber elastic body 16 so as to face each other in the radial direction (left and right direction in FIG. 4). The lower stopper rubber 30 protrudes downward from the contact flange portion 26 of the outer cylindrical member 14, and gradually becomes narrower in the radial direction toward the protruding tip side. Further, a plurality of small protrusions protrude from the surface of the lower stopper rubber 30. The surface of the contact flange portion 26 is covered with a covering rubber layer integrally formed with the main rubber elastic body 16, and a lower stopper rubber 30 is integrally formed so as to protrude downward from the covering rubber layer. ing.

  Further, the main rubber elastic body 16 is integrally formed with a fitting rubber 32 protruding on the outer peripheral surface of the outer cylinder member 14. The fitting rubber 32 is an annular rubber elastic body continuously extending in the circumferential direction. As shown in FIGS. 2 and 5, the three fitting rubbers 32 are separated by a predetermined distance in the axial direction. , 32, 32 are provided on the outer peripheral surface of the outer cylinder member 14. In addition, the axial direction end surface of the fitting rubber 32 is an inclined surface, and the axial dimension of the fitting rubber 32 is gradually reduced toward the outer peripheral side. Further, as shown in FIG. 6, the fitting rubber 32 is integrally formed with the main rubber elastic body 16 through a communication hole 34 provided in the outer cylinder member 14.

  As shown in FIG. 1, the inner shaft member 12 is attached to the vehicle body 18 by a mounting bolt 22 through which the inner shaft member 12 is inserted and a mounting nut 24 screwed to the mounting bolt 22, and the outer cylinder. The member 14 is fitted in the mounting recess 27 provided in the suspension member 20 and attached to the suspension member 20. A fitting rubber 32 is interposed between the outer cylindrical member 14 and the peripheral wall portion of the mounting recess 27, and the fitting rubber 32 is compressed in the radial direction of the outer cylindrical member 14 and the mounting recess 27. Has been.

  A stopper member 36 is fixed to the upper end of the inner shaft member 12. The stopper member 36 includes an upper stopper plate 38 and an upper stopper rubber 40 fixed thereto. The upper stopper plate 38 has a substantially disc shape, and is formed with a bolt insertion hole penetrating the center portion, and a peripheral portion of the bolt insertion hole is formed between the upper end surface of the inner shaft member 12 and the vehicle body 18. It is sandwiched between and fixed. An upper stopper rubber 40 protruding downward is vulcanized and bonded to the upper stopper plate 38. The upper stopper rubber 40 has a cylindrical sealing portion 42 whose inner peripheral portion covers the upper end portion of the inner shaft member 12, and the outer peripheral portion gradually becomes narrower in the radial direction toward the protruding tip. A contact portion 44 is provided.

  The upper stopper plate 38 of the stopper member 36 is disposed to face the upper bottom wall 45 of the mounting recess 27 of the suspension member 20 with a predetermined distance in the axial direction when the suspension member mount 10 is mounted on the vehicle. The As a result, a bound stopper mechanism that limits the amount of axial downward displacement of the inner shaft member 12 relative to the outer cylinder member 14 is realized by the contact between the upper stopper plate 38 and the upper bottom wall portion 45. In addition, since the contact portion 44 of the upper stopper rubber 40 is interposed between the opposing surfaces of the upper stopper plate 38 and the upper bottom wall portion 45, the upper stopper plate 38 and the upper bottom wall portion 45 are brought into contact with each other. The impact is alleviated and the occurrence of hitting sound is prevented. The sealing portion 42 of the upper stopper rubber 40 is pressed against the upper surface of the main rubber elastic body 16 on the outer peripheral side of the inner shaft member 12 to prevent rainwater or the like from adhering to the inner shaft member 12. .

  On the other hand, a lower stopper plate 46 is fixed to the lower end of the inner shaft member 12. The lower stopper plate 46 has a substantially disc shape and is formed with a bolt insertion hole penetrating the center portion. The peripheral edge of the bolt insertion hole is the lower end surface of the inner shaft member 12 and the head of the mounting bolt 22. It is sandwiched between and fixed.

  The lower stopper plate 46 is disposed to face the contact flange portion 26 of the outer cylinder member 14 at a predetermined distance in the axial direction when the suspension member mount 10 is mounted on the vehicle. Thus, a rebound stopper mechanism that limits the amount of axial displacement of the inner shaft member 12 with respect to the outer cylinder member 14 is realized by the contact between the lower stopper plate 46 and the contact flange portion 26. In addition, since the lower stopper rubber 30 is interposed between the opposing surfaces of the lower stopper plate 46 and the contact flange portion 26, the impact caused by the contact between the lower stopper plate 46 and the contact flange portion 26 is reduced. The occurrence of hitting sound is prevented. Since a large number of small protrusions are formed on the surface of the lower stopper rubber 30, the impact at the time of contact with the lower stopper plate 46 is further alleviated, and the hitting sound is further reduced. .

  In the suspension member mount 10 having such a structure, a cylindrical member 48 is attached to a fixed portion of the main rubber elastic body 16 in the inner shaft member 12. The tubular member 48 has a substantially cylindrical fitting portion 50 formed of a hard synthetic resin or metal, and the fitting portion 50 is externally fitted and fixed to an intermediate portion in the axial direction of the inner shaft member 12. The main rubber elastic body 16 is embedded.

  The cylindrical member 48 is formed with a plurality of protrusions 52. As shown in FIG. 5, the protrusions 52 are formed at both ends in the axial direction of the fitting portion 50. As shown by the broken lines in FIG. Projecting toward both sides in the direction (vertical direction in FIG. 6). In short, in this embodiment, the four protrusions 52 are formed, and the cylindrical member 48 is an integrally molded product in which the protrusions 52 are connected to each other at the base end portion. Further, the protrusion 52 protrudes in the radial direction orthogonal to the facing direction of the pair of straight portions 28, 28, and the plurality of protrusions 52 are all positioned away from the pair of straight portions 28, 28 in the circumferential direction. Is provided.

  Further, the projecting tip surface 54 of the projecting portion 52 is a smooth arcuate curved surface having a substantially semicircular shape in the longitudinal section, and has a convex shape toward the outer peripheral side. And the protrusion front end surface 54 of the protrusion 52 is smoothly connected to the surface of the fitting part 50 provided on the base end side without having a break point or the like.

  In addition, a pair of protrusions 52 and 52 are formed apart from each other in the axial direction, so that a recess 56 is formed between the protrusions 52. The recess 56 is formed in the central portion of the cylindrical member 48 in the axial direction, and has a groove shape that opens to the outer peripheral side and extends in the circumferential direction by a predetermined length. Furthermore, it is desirable for the recess 56 to have a maximum axial dimension (axial dimension at the opening) set in a range of 100% to 300% with respect to the depth dimension, and more preferably. , 120% to 200%. In particular, in the recess 56 of the present embodiment, the axial dimension is sufficiently larger than the depth dimension, so that it is relatively shallow.

  The total volume of the recesses 56 is preferably set in a range of 10% to 50%, more preferably 15% to 30% with respect to the volume of the main rubber elastic body 16. ing. In the present embodiment, the total volume of the recesses 56 is set to about 20% of the volume of the main rubber elastic body 16.

  Further, the surfaces on both axial sides of the recess 56 are inclined surfaces 58 that gradually incline outward in the axial direction toward the outer peripheral side. The inclined surface 58 may have a planar shape, but is configured by a combination of curved surfaces in the present embodiment. By providing such an inclined surface 58, the recess 56 has an expanded shape in which the opening is made larger than the bottom surface.

  And the cylindrical member 48 provided with the protrusion 52 and the recess 56 is externally fitted to the inner shaft member 12 in advance, and the main body is provided between the inner shaft member 12 provided with the cylindrical member 48 and the outer cylindrical member 14. The rubber elastic body 16 is vulcanized. As a result, the outer peripheral surface of the cylindrical member 48 is entirely covered with the main rubber elastic body 16 including the formation portion of the protrusion 52, and the cylindrical member 48 including the protrusion 52 becomes the main rubber elastic body 16. The cylindrical member 48 and the outer cylindrical member 14 are connected by the main rubber elastic body 16.

  In the mounting state on the inner shaft member 12, the protrusion 52 protrudes radially outward from the outer peripheral surface of the inner shaft member 12, and to the main rubber elastic body of the outer cylinder member 14 in the axial projection. The protruding height does not reach the fixed surface. Thereby, the main rubber elastic body 16 is interposed between the protruding front end surface 54 of the protrusion 52 and the opposing surface of the outer cylinder member 14 in the direction perpendicular to the axis. In the present embodiment, the inner peripheral surface of the outer cylindrical member 14 has a cylindrical shape extending linearly in the axial direction, and the protrusion 52 does not overlap the outer cylindrical member 14 in the axial projection. The cylinder member 14 is spaced from the inner peripheral side.

  Furthermore, the thickness dimension of the main rubber elastic body 16 between the opposed surfaces of the inner shaft member 12 and the outer cylindrical member 14 is such that the protruding portion 52 is compared with the portion where the protruding portion 52 is formed at the mounting portion of the cylindrical member 48. It is enlarged at a portion where the portion is not formed (the portion where the recess 56 is formed). Referring to FIG. 5, the thickness dimension in the radial direction of the main rubber elastic body 16 is the dimension T of the thick portion 60 that has entered the recess 56, and is fixed to the protruding tip surface 54 of the protrusion 52. The thickness of the thin portion 62 is larger than t.

  Further, in the single member state of the suspension member mount 10, the protrusion 52 on the lower side of the cylindrical member 48 is positioned so that the apex of the protrusion 52 is below the outer cylindrical member 14 as shown in FIG. 5. . Then, when the suspension member mount 10 is mounted on the vehicle and the supporting load of the suspension member 20 is input in the axial direction, as shown in FIG. It fits inside the member 14. Thus, the main rubber elastic body 16 is interposed between the protrusions 52 and the outer cylindrical member 14 facing each other in the direction perpendicular to the axis without any gap. When the suspension member mount 10 is mounted on the vehicle, the main rubber elastic body 16 has a curved shape whose upper end surface is substantially along the surface of the upper protrusion 52 and whose lower end surface extends in a direction substantially perpendicular to the axis. To be deformed.

  In the suspension member mount 10 of the present embodiment having such a structure, the protrusion 52 that protrudes radially outward from the outer peripheral surface of the inner shaft member 12 is provided, so that the spring in the axial direction is provided. Has been hardened. As a result, even when a large shared support load is input from the suspension member 20 that supports the differential device or the like, sufficient load resistance is exhibited and necessary durability can be ensured. . In particular, the main rubber elastic body 16 is fixed so as to cover the entire surface of the protrusion 52, and the protrusion 52 is embedded in the main rubber elastic body 16, so that an axial spring is provided. Can be set to be harder and load resistance can be improved.

  Moreover, the protrusion 52 is formed with a protruding height at which the tip of the protrusion 52 does not reach the fixing surface of the main rubber elastic body 16 in the outer cylindrical member 14 in the axial projection. Therefore, the main rubber elastic body 16 is not sandwiched between the inner shaft member 12 having the protrusion 52 and the outer cylindrical member 14 in the axial direction and compressed, and the divided support input to the suspension member mount 10 is supported. Even when the load is large, the linearity of the spring characteristics is ensured. As a result, it is possible to effectively obtain an anti-vibration effect against input vibration in the vehicle mounted state.

  Further, a plurality of protrusions 52 having a reduced projecting tip area are partially provided in the axial direction, and recesses 56 are formed between the protrusions 52, and the main body rubber is formed in the recesses 56. The elastic body 16 enters and a thick portion 60 is formed. As a result, an increase in the spring constant due to the formation of the protrusion 52 is reduced in the direction perpendicular to the axis, and the spring can be set sufficiently soft. Therefore, it is possible to ensure the degree of freedom in tuning the spring characteristics in the direction perpendicular to the axis, and to achieve the required spring characteristics.

  Furthermore, the inner surfaces of both sides in the axial direction of the recess 56 are inclined surfaces 58 that gradually incline outward in the axial direction toward the outer peripheral side, and the recess 56 gradually expands toward the opening side. Thus, the thick-walled portion 60 of the main rubber elastic body 16 is easily deformed during vibration input, and a small spring constant in the direction perpendicular to the axis and an expansion of the linear region in the axial spring characteristics are more effective. Has been realized.

  The total volume of the recesses 56 is set to 10% or more with respect to the volume of the main rubber elastic body 16. Thereby, the rubber volume of the thick portion 60 of the main rubber elastic body 16 filled in the recess 56 is sufficiently ensured, the spring constant in the direction perpendicular to the axis is reduced, and the linear region of the spring characteristic in the axis direction is reduced. Ensuring is effectively realized in both cases. On the other hand, the total volume of the recesses 56 is set to 50% or less with respect to the volume of the main rubber elastic body 16. As a result, a sufficient volume of the portion other than the thick portion 60 is secured in the main rubber elastic body 16, so that the thin main rubber elastic body 16 disposed between the opposing surfaces of the protrusion 52 and the outer cylindrical member 14 is thin. Also in the portion 62, a sufficient thickness dimension (diameter dimension) is ensured, shear strain due to load input in the axial direction is reduced, and sufficient durability is ensured.

  Further, the projecting tip surface 54 of the projecting portion 52 is a smooth curved surface that is convex toward the outer peripheral side, and is smoothly connected to the inner surface of the recess 56, so that the outer peripheral surface of the cylindrical member 48 is The whole is composed of smooth surfaces without corners. Thus, the outer peripheral surface of the cylindrical member 48 that is the fixing surface of the main rubber elastic body 16 is a smooth surface, so that damage or peeling of the main rubber elastic body 16 due to stress concentration is avoided, Durability is improved.

  Further, the tubular member 48 is formed separately from the inner shaft member 12 and is externally fitted to the inner shaft member 12 and fixed thereafter. As a result, the inner shaft member 12 itself can have a simple straight pipe shape, and is easy to manufacture. In addition, the cylindrical member 48 is formed of a synthetic resin excellent in moldability by utilizing the fact that it is separate from the inner shaft member 12 made of metal in order to ensure rigidity. The protrusion 52 and the recess 56 can be easily formed and set on the outer peripheral surface of the inner shaft member 12.

  The main rubber elastic body 16 is provided with a pair of straight portions 28, 28, and a softer spring is set in the facing direction of the straight portions 28, 28. In addition, since the pair of straight portions 28 and 28 are opposed to each other in the radial direction orthogonal to the protruding direction of the protrusion 52, the pair of straight portions 28 and 28 are arranged in two directions perpendicular to the axis perpendicular to each other by the relatively small straight portion 28. It is possible to set a sufficiently large spring ratio. As a result, in the axial direction, a decrease in spring constant due to the formation of the straight portion 28 is suppressed, and excellent load resistance is realized. In other words, since the protrusions 52 are partially provided on the circumference, the spring ratio in the two directions perpendicular to the axis is set to be large, thereby advantageously ensuring the spring in the axial direction. -ing

  Next, FIG. 7 shows a suspension member mount 70 as a second embodiment of the cylindrical vibration damping device according to the present invention in a mounted state on the vehicle. In the following description, members and portions that are substantially the same as those in the first embodiment are denoted by the same reference numerals in the drawings, and the description thereof is omitted.

  In the suspension member mount 70 of this embodiment, a cylindrical member 72 is attached to the inner shaft member 12. The cylindrical member 72 has a substantially cylindrical shape and includes a fitting portion 50 that is externally fitted to an intermediate portion of the inner shaft member 12 and a plurality of protrusions 74 that project from the fitting portion 50 toward the outer peripheral side. .

  As shown in FIGS. 7 and 8, the protrusion 74 of the present embodiment has a substantially annular shape that continuously extends with a substantially constant cross-sectional shape over the entire circumference, and is predetermined in the axial direction. A pair of protrusions 74 are formed at a distance of. The vertical cross-sectional shape of the protrusion 74 is substantially the same as the vertical cross-sectional shape at the maximum protrusion position of the protrusion 74 of the first embodiment, and the protruding tip surface 54 is substantially semicircular in the vertical cross section. Presents.

  A recess 76 is formed between the pair of protrusions 74 and 74 in the axial direction. The recess 76 has a concave groove shape extending continuously over the entire circumference, and is open to the outer peripheral side. The vertical cross-sectional shape of the recess 76 is substantially the same as the vertical cross-sectional shape of the recess 76 at the maximum projecting position of the protrusion 74 of the first embodiment, and toward the opening side (outer peripheral side). The width gradually increases in the axial direction, and the surfaces on both sides in the axial direction are smoothly connected to the surface of the protrusion 74.

  Also in the suspension member mount 70 having the structure according to this embodiment, the load resistance is improved by the high spring constant in the axial direction and the low spring constant in the direction perpendicular to the axis, as in the first embodiment. The effects of improving the anti-vibration performance by the above and further ensuring the linear region in the spring characteristics are effectively exhibited.

  Further, since the protrusion 74 and the recess 76 are formed in an annular shape extending in the circumferential direction with a substantially constant cross section, the inner shaft member 12 to which the cylindrical member 72 is assembled is connected to the straight portions 28, 28 of the main rubber elastic body 16. There is no need for positioning in the circumferential direction. Therefore, in the vulcanization molding process of the main rubber elastic body 16, the inner shaft member 12 is not vulcanized and bonded to the main rubber elastic body 16 in the wrong direction, and the occurrence of defective products can be suppressed.

  In the suspension member mount 70 of the present embodiment, a large linear region of the spring characteristic is ensured in the axial direction, which is measured in the single item state (not mounted on the vehicle) shown in FIG. It is also clear from the graph showing the actual measurement values of the load-displacement characteristics. That is, the solid line in FIG. 9 showing the load-displacement characteristics of the suspension member mount 70 (Example) shows a conventional structure having a bulge (expanded portion) having no recess 76 in the axially intermediate portion of the inner shaft member. Compared to the broken line in FIG. 9 showing the load-displacement characteristics of the suspension member mount (comparative example), the spring constant in the region where the displacement is small is large. As a result, the suspension member 20 is supported with sufficient spring rigidity, and the deformation amount of the main rubber elastic body 16 is suppressed, so that sufficient durability is ensured. On the other hand, compared to the comparative example, in the example, the increase in load is suppressed from around the amount of displacement exceeding 3a, and the linear region of the spring characteristic is ensured to the larger displacement side. Therefore, in the suspension member mount 70, even when vibration is further input in a state where a large static load is input from the suspension member 20, a rapid increase in the spring constant can be suppressed as compared with the comparative example. Therefore, the intended vibration-proof effect is effectively exhibited. Thus, it has also been confirmed from experimental results that the suspension member mount 70 has an excellent effect that is difficult to achieve with a suspension member mount having a conventional structure.

  Further, a test for confirming the durability of the suspension member mount 70 was performed by applying vibration in a direction perpendicular to the axis from which the protrusion 74 protrudes. That is, as an example, a suspension member mount 70 having a structure according to the present embodiment is prepared, and as a comparative example, a suspension member in which an intermediate sleeve is fixed to the main rubber elastic body between the inner shaft member and the outer cylinder member in the radial direction. Mounts were prepared, and an excitation force in one direction perpendicular to the axis was applied to the suspension member mounts. As a result, the suspension member mount of the comparative example was broken due to cracks in the main rubber elastic body after several tens of thousands of vibrations, but the suspension member mount 70 of the example was also subjected to hundreds of thousands of vibrations. Damage to the extent that would cause problems in performance was not confirmed. As is clear from this, according to the cylindrical vibration isolator having the structure according to the present invention, excellent durability is exhibited even when vibration is input in the direction perpendicular to the axis.

  FIG. 10 shows a suspension member mount 80 as a third embodiment of the cylindrical vibration isolator according to the present invention in a state where it is mounted on a vehicle. A cylindrical member 82 is attached to the inner shaft member 12 of the suspension member mount 80.

  The cylindrical member 82 is integrally provided with a fitting portion 84 having a thick, substantially cylindrical shape, and a plurality of projections 86 protruding from the fitting portion 84 to the outer peripheral side.

  The protrusions 86 extend in a circumferential ring shape, and a plurality of protrusions 86 are formed at a predetermined distance in the axial direction. In addition, the protrusions 86 and 86 at both ends in the axial direction are larger than the other protrusions 86 each having an axial dimension in the middle. Further, the protrusion 86 located at the lower end has a protrusion height smaller than that of the other protrusions 86.

  A recess 88 is formed between the protrusions 86 adjacent in the axial direction. The recess 88 is formed in a concave groove shape that continuously extends over the entire circumference, and opens while gradually widening toward the outer peripheral side. Further, a plurality of recesses 88 are formed at a predetermined distance in the axial direction by sandwiching the protrusions 86, and the protrusions 86 and the recesses 88 are repeatedly formed on the outer peripheral surface of the cylindrical member 82. As a result, it has a wavy shape.

  According to the suspension member mount 80 having the structure according to this embodiment, in addition to the effects shown in the first embodiment, many recesses 88 are formed, and the main rubber elastic body 16 The thick part 60 is divided into a large number and formed. Thereby, at the time of vibration input, the strain input to the thick portion 60 of the main rubber elastic body 16 is dispersed, and the strain of each thick portion 60 is reduced. As a result, the main rubber elastic body 16 is prevented from being cracked, peeled off from the tubular member 82, and the like, and the durability is improved.

  As mentioned above, although embodiment of this invention was explained in full detail, this invention is not limited by the specific description. For example, the cross-sectional shape of the protrusion is not limited to that described in the embodiment. Specifically, for example, the protruding tip surface of the protrusion has a cylindrical portion having a predetermined width in the axial direction and extending in the circumferential direction, in other words, a flat portion extending in the axial direction in the longitudinal section. May be.

  In addition, it is desirable that the plurality of protrusions 52 be separated from each other in the axial direction. However, the protrusions 52 may not necessarily be provided at both ends of the cylindrical member 48, and may be fitted to the inner shaft member 12. The landing part 50 may protrude outward in the axial direction from the position where the protrusion 52 is formed.

  Moreover, in the said embodiment, the protrusion 52 is formed in the cylindrical member 48 separate from the inner shaft member 12, and when the cylindrical member 48 is externally fitted to the inner shaft member 12, the inner shaft Although the protrusion 52 was provided on the outer peripheral surface of the member 12, the protrusion may be integrally formed with the inner shaft member, for example.

  Further, in the above-described embodiment, the projection 52 is located on the inner peripheral side with respect to the outer cylinder member 14 in the axial projection, but the protrusion 52 is fixed to the fixing surface of the main rubber elastic body 16 on the outer cylinder member 14. If they are separated from each other on the inner peripheral side, an overlapping structure in the axial projection can be adopted. Specifically, for example, the outer cylinder member extends to the inner peripheral side at a position where the main rubber elastic body 16 deviates in the axial direction, and the extended portion overlaps the protrusion 52 in the axial projection. Also good.

  The pair of straight portions 28 and 28 are preferably formed for adjusting the spring ratio in two directions perpendicular to the axis and for reducing the spring constant in the direction perpendicular to the axis. Some vibration characteristics can be omitted. Furthermore, the specific structure of the straight portion is not particularly limited, and for example, a concave straight portion that does not penetrate in the axial direction may be employed.

  The present invention is not necessarily applied only to a tubular vibration isolator for automobiles, and can also be applied to a cylindrical vibration isolator used for, for example, a motorcycle, a railway vehicle, an industrial vehicle, and the like. Furthermore, the cylindrical vibration isolator according to the present invention can be employed not only for suspension member mounts but also for engine mounts and differential mounts.

10, 70, 80: Suspension member mount (cylindrical vibration isolator), 12: Inner shaft member, 14: Outer cylinder member, 16: Rubber elastic body of main body, 28: Straight part, 48, 72, 82: Cylindrical member , 52, 74, 86: protrusion, 54: protruding tip surface, 56, 76, 88: recess, 58: inclined surface

Claims (7)

In the cylindrical vibration isolator in which the outer cylindrical member is disposed on the outer peripheral side of the inner shaft member, and the inner shaft member and the outer cylindrical member are connected by the main rubber elastic body,
A plurality of protrusions are provided on the outer peripheral surface of the inner shaft member fixed to the main rubber elastic body so as to be spaced apart from each other in the axial direction. The projecting height does not reach the fixing surface of the main rubber elastic body in the cylindrical member, and the protrusions are embedded in the main rubber elastic body,
The thickness dimension of the main rubber elastic body between the opposed surfaces of the inner shaft member and the outer cylindrical member is made larger at the portion where the protrusion is not formed than at the portion where the protrusion is formed. A cylindrical vibration isolator characterized by comprising:   2. The cylindrical shape according to claim 1, wherein a side surface of a recess formed between the plurality of protrusions in the axial direction is an inclined surface, and the recess gradually widens in the axial direction toward the opening side. Anti-vibration device.   The cylindrical vibration isolator according to claim 1 or 2, wherein a protruding tip surface of the protrusion is a convex curved surface.   The volume of the recess formed between the axial directions of the plurality of protrusions is set to 10% or more and 50% or less of the volume of the main rubber elastic body. The cylindrical vibration isolator as described.   The cylindrical vibration isolator according to any one of claims 1 to 4, wherein the main rubber elastic body is formed with a pair of straight portions sandwiching the inner shaft member in a radial direction.   The plurality of protrusions are formed in an annular shape extending in the circumferential direction, and recesses formed between the axial directions of the plurality of protrusions are formed in a groove shape extending continuously over the entire circumference. The cylindrical vibration isolator according to any one of 1 to 5.   The cylinder according to any one of claims 1 to 6, wherein a separate cylindrical member is externally fitted to the inner shaft member, and the plurality of protrusions are formed with respect to the cylindrical member. Shape anti-vibration device.

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