JP5399147B2 - Vibration isolator - Google Patents

Description

  The present invention relates to a fluid-filled vibration isolator that prevents transmission of vibration from a member that generates vibration, and more particularly, to a vibration isolator that is suitably used for an engine mount of an automobile.

  For example, in a vehicle such as a passenger car, an anti-vibration device serving as an engine mount is disposed between an engine serving as a vibration generating unit and a vehicle body serving as a vibration receiving unit. In the vibration isolator, when the inner cylinder and the outer cylinder vibrate in the axial direction due to vibration generated from the engine, the vibration is attenuated by liquid movement between the main liquid chamber and the sub liquid chamber. . For example, in the vibration isolator described in Patent Document 1, in addition to the above structure, a plurality of fluid chambers (liquid chambers) are also arranged in a direction orthogonal to the axial direction (axial direction) to vibrate in the axial direction. Attenuation is caused by liquid movement between a plurality of liquid chambers.

  By the way, in the structure described in Patent Document 1, a movable rubber film is provided that forms a through hole penetrating the inner shaft member in a direction perpendicular to the axis and closes the through hole in a fluid-tight manner. By being exposed to the pressure, the structure is designed to relieve pressure fluctuations in the fluid chamber (so-called “pressure release”) against high-frequency vibrations.

  However, in the structure of Patent Document 1, since the movable rubber film is provided in the through hole formed in the inner shaft member, the shape and size of the movable rubber film are limited, and there is a limit to effectively perform the pressure relief. is there. Further, since the inner shaft member is generally made of metal, manufacturing costs are increased if through holes are formed in the metal member.

JP 2006-64119 A

  In consideration of the above facts, the present invention can effectively perform pressure release in the axial direction in a vibration isolator that attenuates vibration not only in the main vibration direction but also in the axial direction perpendicular to the main vibration direction. In addition, an object is to obtain a vibration isolator that can be manufactured at low cost.

  In the first aspect of the present invention, the first mounting member is formed in a cylindrical shape and connected to one of the vibration generating portion and the vibration receiving portion, and is connected to the other of the vibration generating portion and the vibration receiving portion, and the first mounting member A second mounting member disposed on the inner peripheral side of the member, an elastic body disposed between the first mounting member and the second mounting member and connecting the first mounting member and the second mounting member; Liquid is sealed between the partition member and the partition member constituting the main liquid chamber in which the liquid is sealed between the elastic member and the internal volume changes with elastic deformation of the elastic body. And a diaphragm member constituting a sub liquid chamber whose internal volume changes in response to a change in liquid pressure, a first restricting passage enabling movement of liquid between the main liquid chamber and the sub liquid chamber, A recess that is provided in the elastic body and forms a liquid chamber between the first mounting member and the liquid chamber; A partition partitioning into a plurality of pressure receiving liquid chambers arranged in a direction intersecting the axial direction of the first mounting member, a plurality of the pressure receiving liquid chambers, or each of the pressure receiving liquid chambers and the sub liquid chamber A second restriction passage that allows liquid to move between them, and a pressure difference reducing means that is provided in the partition and reduces the pressure difference between the plurality of pressure receiving liquid chambers.

  In this vibration isolator, when vibration is transmitted from the vibration generating portion to one of the first mounting member and the second mounting member, the vibration isolator is disposed between the first mounting member and the second mounting member to connect them. The elastic body is elastically deformed. Then, the vibration is absorbed by the vibration absorbing action based on the internal friction or the like of the elastic body, and the vibration transmitted to the vibration receiving portion side is reduced.

  Liquid is sealed in each of the main liquid chamber formed between the elastic body and the partition member and the sub liquid chamber formed between the partition member and the diaphragm member. The movement of the liquid with the sub liquid chamber is enabled by the first restriction passage. Therefore, when the first mounting member and the second mounting member vibrate in the axial direction and the internal volume of the main liquid chamber changes with the elastic deformation of the elastic body, a part of the liquid moves between the sub liquid chamber. Therefore, this can absorb the input vibration in the axial direction.

  Further, in this vibration isolator, a liquid chamber is formed between the concave portion provided in the elastic body and the first mounting member, and the liquid chamber intersects the axial direction of the first mounting member by the partition wall. Are divided into a plurality of pressure receiving liquid chambers. Then, the movement of the liquid between the plurality of pressure receiving liquid chambers or between each of the pressure receiving liquid chambers and the sub liquid chamber is enabled by the second restriction passage. Therefore, when the first mounting member and the second mounting member vibrate in a direction orthogonal to the axial direction (axial direction), the pressure receiving liquid chambers or between each of the pressure receiving liquid chambers and the sub liquid chambers. The liquid moves. Thereby, the input vibration can be absorbed even in the direction perpendicular to the axis.

  The partition wall is provided with pressure difference reducing means for reducing the pressure difference between the plurality of pressure receiving liquid chambers. Therefore, when high-frequency vibration (for example, vibration that prevents the second restriction passage from acting as a liquid movement passage) is input in the direction perpendicular to the axis, the pressure difference reducing means reduces the pressure difference between the plurality of pressure receiving liquid chambers, The pressure fluctuation in the pressure receiving liquid chamber is suppressed (so-called “pressure release” is performed). Thus, even when high-frequency vibration is input in the direction perpendicular to the axis, the vibration can be absorbed and the function as a vibration isolator can be exhibited.

  Moreover, the pressure difference reducing means is provided on the partition wall. Since it is not necessary to process the second mounting member or the like such as providing a through hole, it can be manufactured at low cost. In addition, compared to the configuration in which the movable rubber film is provided in the through hole of the second mounting member, the degree of freedom of the shape and size of the portion that substantially acts as the pressure release is increased. It becomes possible to carry out effectively.

  According to a second aspect of the present invention, in the first aspect of the present invention, the pressure difference reducing means is constituted by a thin portion in which the partition wall is locally thinned, and a portion of the partition wall other than the thin portion. Is a thick part that is relatively thicker than the thin part.

  Therefore, the pressure difference between the pressure receiving liquid chambers, that is, the pressure fluctuation can be absorbed by the deformation of the thin portion. Since the pressure difference reducing means can be configured only by forming the thin wall portion on the partition wall, the influence on the performance of the entire vibration isolator is reduced, and the original vibration isolating performance of the vibration isolator can be maintained high.

  Moreover, the part other than the thin part of the partition is a thick part that is relatively thicker than the thin part. Therefore, it is possible to support a part of the axial load of the first mounting member and the second mounting member by the thick portion.

  According to a third aspect of the present invention, in the second aspect of the present invention, the thick portion is continuous from one end to the other end in the axial direction in the partition wall.

  Therefore, it is possible to more reliably support a part of the axial load as compared with a configuration in which the thick portion is not continuous from one end to the other end in the axial direction.

  In the invention of claim 4, in the invention of claim 2 or claim 3, the thin portion is formed in a circular shape when the partition is viewed from the front.

  Thus, by making a thin part circular, the effect of the pressure relief with respect to the area of a thin part can be exhibited highly compared with the case where it is set as shapes other than circular. In addition, when the thin wall portion is formed in a polygonal shape, for example, corners exist around the thin wall portion, so stress concentration may occur in the corner portions. Since there is no stress, stress concentration does not occur, and the durability of the partition wall is increased.

  The invention according to claim 5 is the invention according to any one of claims 1 to 4, wherein the elastic body is gradually expanded from the second mounting member toward the partition member. A conical portion having a truncated cone shape, and a lid portion that extends radially outward from the second mounting member on the opposite side of the partition member when viewed from the cone portion and serves as a lid for the liquid chamber. ing.

  By forming the frustoconical conical portion on the elastic body, the main liquid chamber can be formed between the elastic member and the partition member, and a large volume as the elastic body can be secured, resulting in high durability. Moreover, the liquid chamber (pressure receiving liquid chamber) between the concave portion of the elastic body and the first mounting member can be reliably maintained by configuring the liquid chamber lid by the lid portion extended from the elastic body.

  Since the present invention is configured as described above, it is possible to effectively perform pressure relief in the axial direction in the vibration isolator that attenuates vibration not only in the main vibration direction but also in the axial direction perpendicular to the main vibration direction. Moreover, it can be manufactured at low cost.

It is a perspective view which fractures | ruptures and shows the structure of the vibration isolator which concerns on 1st Embodiment of this invention along an axial direction. It is a perspective view which shows the internal structure of the vibration isolator which concerns on 1st Embodiment of this invention. It is a perspective view which fractures | ruptures and shows the internal structure of the vibration isolator which concerns on 1st Embodiment of this invention to the axial direction. It is sectional drawing of the axial direction which shows the structure of the vibration isolator which concerns on 1st Embodiment of this invention. It is sectional drawing of the direction of an axial direction which shows the structure of the vibration isolator which concerns on 1st Embodiment of this invention. It is a graph which shows the relationship between the input frequency which acts on the axial direction of a vibration isolator, the dynamic spring constant in the amplitude of +/- 0.3mm, and the loss coefficient in the amplitude of +/- 1.0mm. It is a perspective view which fractures | ruptures and shows the internal structure of the vibration isolator which concerns on the modification of 1st Embodiment of this invention to the axial direction. It is a perspective view which fractures | ruptures and shows the internal structure of the vibration isolator which concerns on the modification of 1st Embodiment of this invention to the axial direction. It is sectional drawing of the axial direction which shows the structure of the vibration isolator which concerns on the modification of 1st Embodiment of this invention. The structure of the vibration isolator which concerns on the modification of 1st Embodiment of this invention is partially expanded and shown in a partition, (A) is sectional drawing of a vertical direction, (B) is XX of (A). It is sectional drawing.

  FIG. 1 shows a vibration isolator 12 according to a first embodiment of the present invention. The vibration isolator 12 is used as an engine mount in an automobile, for example. An engine serving as a vibration generating unit is supported on a vehicle body serving as a vibration receiving unit. In the drawings, symbol S indicates the axial center of the vibration isolator 12. The direction along the axial center S is the axial direction of the vibration isolator 12, and the direction orthogonal to the axial center S (axial direction) is prevented. The radial direction of the vibration device 12 is assumed.

  As shown in detail in FIG. 2, the vibration isolator 12 has an outer cylinder 14 formed in a substantially cylindrical shape. At a position below the center in the axial direction of the outer cylinder 14, a reduced diameter portion 14N that is reduced in diameter via a stepped portion 14D is formed. Also, a substantially cylindrical covering rubber 16 is vulcanized and coated over substantially the entire inner peripheral surface of the outer cylinder 14. From the vicinity of the lower end of the covering rubber 16, a diaphragm 18 is integrally extended radially inward.

  The diaphragm 18 is a film-like member that is curved so that a central portion thereof is convex upward, and forms a sub liquid chamber 30 between the diaphragm 18 and the orifice cylinder 26 described later. The sub liquid chamber 30 is expanded and contracted by the deformation of the diaphragm 18 so that the volume thereof is changed. The lower end of the covering rubber 16 wraps around from the lower side of the outer cylinder 14 to the outer side in the radial direction, and is in close contact with the outer peripheral surface of the reduced diameter portion 14N. The outer cylinder 14 and the covering rubber 16 constitute a first mounting member 20 according to the present invention.

  A plurality of (for example, three) leg portions (not shown) extend radially outward from the outer cylinder 14, and the vibration isolator 12 is inserted into the bolt insertion hole at the tip of the leg portion. It can be attached to the car body. Instead of (or in combination with) the legs, a bracket may be fixed to the outer cylinder 14 and the outer cylinder 14 may be attached to the vehicle body using the bracket.

  A cylindrical inner cylinder 22 is disposed inside the outer cylinder 14 so as to be positioned at the axis S. The lower bottom portion of the inner cylinder 22 is closed, but the upper bottom portion is opened and a female screw 22M is formed on the inner periphery. An engine-side bolt or the like is screwed into the female screw 22M, for example, so that the engine is supported by the vibration isolator 12. Note that the vibration isolator 12 of the present embodiment also has an effect of attenuating vibration in the axial direction, but the axis of the inner cylinder 22 is the axis of the outer cylinder 14 when no vibration is input. Is consistent with

  A rubber elastic body 24 is disposed between the inner cylinder 22 and the outer cylinder 14 (covering rubber 16), and the inner cylinder 22 and the outer cylinder 14 are connected by the rubber elastic body 24. Further, an orifice cylindrical body 26 and a partition disk 32 are arranged between the rubber elastic body 24 and the diaphragm 18 or the covering rubber 16.

  The rubber elastic body 24 has a truncated cone-shaped rubber main body portion 24 </ b> B that is extended from the lower portion of the inner cylinder 22 toward the orifice cylindrical body 26 and gradually expanded in diameter. Further, from the upper side of the rubber body 24B, the diameter gradually increases while extending toward the upper end of the outer cylinder 14 (that is, toward the side opposite to the partition disk 32 when viewed from the rubber body 24B). And a lid portion 24L. And the liquid chamber 40 which concerns on this invention is comprised among the rubber main-body part 24B, the cover part 24L, and the 1st attachment member 20 (covering rubber | gum 16). By making the rubber main body portion 24B such a shape, the volume can be increased, and the durability is improved.

  The orifice cylindrical body 26 has a substantially disc-shaped orifice disc portion 26D, and a substantially cylindrical orifice cylinder portion 26E that is erected upward from the outer periphery of the orifice disc portion 26D. The outer edge portion of the lower surface of the orifice cylindrical portion 26E is supported on the rubber elastic body 16 at the step portion 14D. A partition disk 32 is supported above the orifice disk part 26D, and a main liquid chamber 28 is formed between the partition disk 32 and the rubber main body part 24B of the rubber elastic body 24. ing. The main liquid chamber 28 is filled with a liquid such as ethylene glycol or silicon oil. Further, a sub liquid chamber 30 is formed between the orifice disk portion 26 </ b> D and the diaphragm 18. Similarly to the main liquid chamber 28, the sub liquid chamber 30 is filled with a liquid such as ethylene glycol or silicon oil.

  At the center of the orifice disc portion 26D, an upper concave portion 56A having a concave upper surface side and a lower concave portion 56B having a circular concave portion on the lower surface side are formed, whereby the orifice disc portion 26D is partially thinned. A thin portion 58 is formed. The circular membrane 34 is accommodated in the upper recess 56A without any gaps, and the membrane 34 is covered with a partition disk 32 from above. A plurality of through holes 60 and 62 are formed in the thin wall portion 58 and the partition disk 32 so that the pressure of the main liquid chamber 28 and the sub liquid chamber 30 acts on the membrane 34 through the through holes 60 and 62, respectively. It has become.

  An annular thin ring portion 34S is formed in the membrane 34, and relative fluctuations in the pressures of the main liquid chamber 28 and the sub liquid chamber 30 are generated at a high frequency that cannot be absorbed by fluid movement through the first orifice 36 described later. Then, the thin ring portion 34S of the membrane 34 is deformed, and this pressure fluctuation is alleviated.

  A spiral first orifice 36 surrounding the thin portion 58 is formed in the orifice disc portion 26D. The upper end of the first orifice 36 communicates with the main liquid chamber 28 through a communication hole 38 formed in the partition disk 32, and the lower end of the first orifice 36 opens downward and communicates with the sub liquid chamber 30. . Thus, the first orifice 36 is a flow path that allows the liquid to move between the main liquid chamber 28 and the sub liquid chamber 30. In particular, the length and cross-sectional area of the first orifice 36 as a flow path are set corresponding to vibrations in a specific frequency range (for example, shake vibrations), and the liquid in the main liquid chamber 28 and the sub liquid chamber 30 is set. The vibration energy is adjusted to be absorbed by the movement.

  As can be seen from FIGS. 2 and 3, two partition walls 42 that partition the liquid chamber 40 in the direction perpendicular to the axis are formed between the rubber body 24 </ b> B and the lid 24 </ b> L. The partition wall 42 has a symmetrical shape about the axis S and is continuous from the lid portion 24L to the rubber main body portion 24B. Further, as shown in FIGS. 4 and 5, the tip end of the partition wall 42 (the end portion farthest from the axis S) is in pressure contact with the inside of the first mounting member 20 (covering rubber 16). The partition wall 42 divides the liquid chamber 40 into two pressure receiving liquid chambers 40A and 40B. As can be seen from FIG. 4, the upper portion of the partition wall 42 extends upward from the lid portion 24L.

  As shown in FIG. 1, a flat cylindrical holding cylinder 44 is disposed on the outer peripheral surface of the rubber main body 24 </ b> B of the rubber elastic body 24 and is vulcanized and bonded. The holding cylinder 44 is pressure-bonded to the inner peripheral surface of the orifice cylindrical portion 26E of the orifice cylindrical body 26, so that inadvertent misalignment between the rubber elastic body 24 and the orifice cylindrical body 26 is suppressed. A ring-shaped holding ring 46 is disposed on the outer peripheral surface of the lid portion 24L of the rubber elastic body 24 and is vulcanized and bonded. The lower surface of the holding ring 46 is in close contact with the upper surface of the outer cylinder 14, and the lid 24 </ b> L of the rubber elastic body 24 is fixed to the outer cylinder 14 by fixing the holding ring 46 to the outer cylinder 14. .

  The holding cylinder 44 and the holding ring 46 are connected and integrated by a plurality of support plates 48 formed therebetween. In the present embodiment, as shown in detail in FIG. 5, two support plates 48 are formed so as to be symmetrical with respect to the axis S, and have a predetermined length (see FIG. 5) in the circumferential direction. Width) and is formed so as to be located in the middle of the partition wall 42. Each of the support plates 48 is curved in an arc shape with the axis S as the center, and the inner surface of the support plate 48 (the inner peripheral surface on the axis S side) has a rubber main body 24B of the rubber elastic body 24 and The rubber constituting the lid portion 24L is extended and vulcanized and bonded, and the inner surface side of the support plate 48 is covered with this rubber. On the other hand, the outer surface of the support plate 48 is pressed against the covering rubber 16.

  In the present embodiment, the holding cylinder 44, the holding ring 46, and the support plate 48 are integrally formed of metal or the like, and the rubber elastic body 24 is vulcanized and bonded inside the holding cylinder 44 and the holding ring 46. ing. And the member integrated in this way is press_fitted inside the 1st attachment member 20 (covering rubber | gum 16).

  In this embodiment, in particular, the support plate 48 is supported so that the width direction (the direction along the inner peripheral surface of the covering rubber 16) and the partition wall 42 are substantially parallel when viewed in the direction along the axis S. The positional relationship between the plate 48 and the partition wall 42 is determined. In other words, when viewed in the direction along the axis S, the support plates 48 and the partition walls 42 are alternately arranged at equal intervals in the circumferential direction at a central angle of 90 degrees.

  A concave groove 50 is formed on the outer peripheral surface of the orifice cylindrical portion 26E of the orifice cylindrical body 26. In the portion where the concave groove 50 is formed, two second orifices 52A corresponding to the pressure receiving liquid chambers 40A and 40B, respectively, between the orifice cylindrical portion 26E and the first mounting member 20 (covering rubber 16). 52B is configured. The second orifices 52 </ b> A and 52 </ b> B are partially opened at the upper ends thereof to communicate with the corresponding pressure receiving liquid chambers 40 </ b> A and 40 </ b> B, respectively, and the lower ends thereof are also opened to communicate with the auxiliary liquid chamber 30. Accordingly, the second orifices 52A and 52B are flow paths that allow the fluid to move between the corresponding pressure receiving liquid chambers 40A and 40B and the sub liquid chamber 30, respectively. The lengths and cross-sectional areas of the second orifices 52A and 52B as flow paths are set corresponding to vibrations in a specific frequency range, and liquid movement between the pressure receiving liquid chambers 40A and 40B and the auxiliary liquid chamber 30 The vibration energy is adjusted so as to be absorbed.

  As shown in detail in FIGS. 4 and 5, each of the partition walls 42 has a circular recess in which both surfaces of the partition wall 42 are locally recessed at a position approximately in the center in the vertical direction and approximately in the center in the radial direction. 54 is formed. That is, in the partition wall 42, a thin portion 42U that is locally thin is formed by the recess 54, and a portion other than the thin portion 42U is a relatively thick portion 42A. In particular, the thick portion 42A has a shape that continues from the upper end (lid portion 24L) to the lower end (rubber body portion 24B) on the radially outer side and the inner side of the partition wall 42. The recess 54 is formed to be circular when the partition wall 42 is viewed from the front.

  When the thickness of the partition wall 42 in the thin wall portion 42U is generated at a high frequency such that the relative fluctuation in the pressure receiving liquid chambers 40A and 40B cannot be absorbed by the fluid movement with the sub liquid chamber 30 through the second orifices 52A and 52B, It is determined so that the pressure fluctuation can be reduced by the deformation of the thin portion 42U. On the other hand, the thickness of the thick wall portion 42A is such that the partition wall 42 is securely pressed against the covering rubber 16 so that the space between the partition wall 42 and the covering rubber 16 is liquid-tight, and the lid portion 24L is reliably supported. At the same time, when the inner cylinder 22 and the outer cylinder 14 move relative to each other, they are elastically deformed so that a resistance against the relative movement is exhibited, and the energy of the relative movement can be effectively dissipated by the internal friction. ing.

  Next, the operation of the vibration isolator 12 of this embodiment will be described.

  When the engine is activated, vibration from the engine is transmitted to the rubber elastic body 24 through the inner cylinder 22. At this time, the rubber elastic body 24 acts as a vibration absorber, and the input vibration is absorbed by a damping action due to internal friction or the like accompanying the deformation of the rubber elastic body 24.

  Here, the main vibrations input from the engine to the vibration isolator 12 are vibrations (main vibrations) generated when the piston in the engine reciprocates in the cylinder, and the rotation speed of the crankshaft in the engine changes. Vibration (sub-vibration) generated by the operation. In addition, vibrations input to the vibration isolator 12 from the vehicle body side include inputs close to the main vibration and the sub vibration described above. The rubber elastic body 24 can be absorbed by a damping action due to internal friction or the like, regardless of whether the input vibration is a main vibration or a secondary vibration. Actually, a vibration obtained by combining the main vibration and the sub-vibration acts on the vibration isolator 12, but for the sake of convenience, the behavior of the vibration isolator 12 will be described separately for each vibration. In this vibration isolator 12, as an example of the arrangement direction, the main amplitude direction is aligned with the axial direction of the vibration isolator 12, and the sub-amplitude direction is aligned with the axial direction of the vibration isolator 12. doing.

  First, the case where the main vibration is input to the vibration isolator 12 will be described. In the vibration isolator 12, the main liquid chamber 28 communicates with the sub liquid chamber 30 through the first orifice 36. Therefore, when main vibration is input to the inner cylinder 22 from the engine side, the rubber elastic body 24 is elastically deformed along the main amplitude direction, and the internal volume of the main liquid chamber 28 is expanded and contracted. As a result, the liquid flows between the main liquid chamber 28 and the sub liquid chamber 30 through the first orifice 36 in synchronization with the input vibration.

  Here, the path length and the cross-sectional area of the first orifice 36 are set to correspond to the frequency of a specific input vibration (for example, shake vibration). Therefore, a resonance phenomenon (liquid column resonance) occurs in the liquid that flows between the main liquid chamber 28 and the sub liquid chamber 30 through the first orifice 36. The input vibration in the main amplitude direction can be particularly effectively absorbed by the pressure change and viscous resistance of the liquid accompanying the liquid column resonance.

  Further, when the frequency of the input vibration in the main amplitude direction is high and the first orifice 36 is clogged, that is, when the liquid becomes difficult to flow, the membrane 34 vibrates along the axial direction in synchronization with the input vibration. As a result, an increase in the dynamic spring constant accompanying an increase in the hydraulic pressure in the main liquid chamber 28 can be suppressed. That is, even when such high-frequency vibration is input in the main amplitude direction, the so-called “pressure release” is performed to keep the dynamic spring constant of the rubber elastic body 24 low. Vibration can be effectively absorbed.

  Next, the case where the secondary vibration is input to the vibration isolator 12 will be described. In the vibration isolator 12 of the present embodiment, the pressure receiving liquid chambers 40A and 40B are communicated with the sub liquid chamber 30 through the second orifices 52A and 52B, respectively. Therefore, when a secondary vibration is input to the inner cylinder 22 from the engine side, the rubber elastic body 24 is elastically deformed along the sub-amplitude direction, and the internal volumes of the pressure receiving liquid chambers 40A and 40B are expanded and contracted. As a result, the liquid flows between the pressure receiving liquid chambers 40A and 40B and the sub liquid chamber 30 through the second orifices 52A and 52B in synchronization with the input vibration.

  Here, the path length and the cross-sectional area in the second orifices 52A and 52B are set so as to correspond to the frequency of a specific input vibration. For this reason, a resonance phenomenon (liquid column resonance) occurs in the liquid that flows between the pressure receiving liquid chambers 40A and 40B and the sub liquid chamber 30 through the second orifices 52A and 52B. The input vibration in the sub-amplitude direction can be particularly effectively absorbed by the pressure change and viscous resistance of the liquid accompanying the liquid column resonance.

  Further, when the frequency of the input vibration in the sub-amplitude direction is high and the second orifices 52A and 52B are clogged, that is, when it becomes difficult for the liquid to flow, the thin portion 42U of the partition wall 42 vibrates in synchronization with the input vibration. . As a result, an increase in the dynamic spring constant associated with a change in the fluid pressure in the pressure receiving fluid chambers 40A and 40B can be suppressed. That is, in the present embodiment, the dynamic spring constant of the rubber elastic body 24 is kept low by performing so-called “pressure release” not only in the main vibration direction but also in the input of the high-frequency vibration in the sub-vibration direction. High-frequency vibrations can be effectively absorbed by the elastic deformation of the rubber elastic body 24.

  FIG. 6 shows an example of the relationship between the dynamic spring constant and the loss coefficient of the rubber elastic body 24 with respect to the frequency of the input vibration in the sub-amplitude direction. In this graph, the thick line indicates the dynamic spring constant, and the thin line indicates the loss coefficient. Moreover, in each, the continuous line has shown the vibration isolator 12 of this embodiment, and the dashed-two dotted line has shown the vibration isolator of the comparative example. In the vibration isolator of the comparative example, a portion corresponding to the thin portion 42U of the present embodiment is not formed in the partition wall 42, but the other structure is the same as that of the vibration isolator 12 of the present embodiment.

  In this graph, first, as can be seen by comparing the solid line of the thin line and the two-dot chain line, in the high frequency region (for example, 15 Hz or more), the present embodiment and the comparative example have almost the same loss factor. . Further, as can be seen by comparing the bold solid line and the two-dot chain line, in this embodiment, the dynamic spring constant is lower in the present embodiment than in the comparative example. In particular, in the vibration isolator having a structure in which each of the pressure receiving liquid chambers 40A and 40B communicates with the sub liquid chamber, it is assumed that the dynamic spring constant in the high frequency region is increased. The dynamic spring constant at is reliably reduced.

  Moreover, in the vibration isolator 12 of this embodiment, the part other than the thin part 42U in the partition wall 42 is a thick part 42A, and the partition wall 42 has a predetermined thickness by the thick part 42A. Therefore, the vibration damping effect in the direction perpendicular to the axis can be sufficiently exhibited. In addition, the lid portion 24L of the rubber elastic body 24 can be reliably supported with respect to the rubber main body portion 24B by the thick portion 52A. In particular, the thick portion 42A has a shape that continues from the upper end (lid portion 24L) to the lower end (rubber body portion 24B) on the radially outer side and the inner side of the partition wall 42. For this reason, when the main vibration in the main amplitude direction is input to the inner cylinder 22, a part of the load can be supported by the thick portion 42A (the rubber elastic body 24 as a whole has a portion that can support the load in the main vibration direction. It will increase).

  Moreover, in the vibration isolator 12 of this embodiment, in order to perform “pressure release” in the direction perpendicular to the axis, it is only necessary to form the thin wall portion 42U in the partition wall 42, and the shape of other parts in the vibration isolator 12 can be changed. Therefore, the influence on the overall performance of the vibration isolator 12 is reduced. That is, the vibration isolator 12 can maintain the originally required vibration isolating performance.

  Of course, the thin portion according to the present invention is not limited to the circular thin portion 42U described above. That is, it is only necessary that “pressure release” can be performed on the pressure receiving liquid chambers 40A and 40B. However, when the shape is not circular, the curvature of the outer peripheral portion of the thin portion 42U changes when the thin portion 42U is viewed from the front. In particular, when the thin-walled portion 42U is formed in, for example, a polygonal shape or the like, a portion having a locally large curvature (corresponding to a corner portion) is present, and thus stress concentration tends to occur in such a portion. On the other hand, it is preferable to make the thin-walled portion circular because stress concentration can be prevented and durability becomes high. In addition, when the thin portion 42U is made circular, the effect of “pressure release” on the area when the thin portion 42U is viewed from the front is enhanced as compared with a shape other than the circular shape.

  Moreover, although the example which formed the thin part 42U in both surfaces in each of the two partition 42 was mentioned above, the site | part and number which form the thin part 42U are not limited to this. For example, as in the first modification shown in FIG. 7, the thin portion 42 </ b> U may be formed only on one surface of each partition wall 42. Moreover, you may form the thin part 42U in both surfaces only in one partition 42 like the 2nd modification shown in FIG.

  Further, in the above, the support plate 48 so that the width direction of the support plate 48 (the direction along the inner peripheral surface of the covering rubber 16) and the partition wall 42 are substantially parallel when viewed in the direction along the axis S. However, instead of this, for example, as shown in FIG. 9, a support plate 48 is disposed on the front end side (the side far from the inner cylinder 22) of the partition wall 42 and vulcanized and bonded to the partition wall 42. Other configurations may be used. In the structure shown in FIG. 9, since the tip of the partition wall 42 is pressed against the covering rubber 16, when an excessive input acts on the partition wall 42, a slight deviation (however, the covering rubber 16 is provided between the covering rubber 16). No gap is formed with respect to the outer wall 16, and the stress concentration on the partition wall 42 can be alleviated, so that the durability is improved. However, when the rubber elastic body 24 having the structure shown in FIG. 5 is manufactured, it is difficult to pull out the mold only by a single pulling direction with respect to the mold (for example, when pulling in the direction of the arrow N1). It is difficult to remove the mold part that has entered the recess 54. Also, when the mold part is pulled out in the direction of the arrow N2, it hits the support plate 48), and the structure of the mold becomes complicated. On the other hand, in the structure shown in FIG. 9, when the rubber elastic body 24 is manufactured, the mold can be pulled out in the direction of the arrow N3.

  Furthermore, the pressure difference reducing means of the present invention is not limited to the thin portion 42U in which the partition wall 42 is partially thinned, and may have a modified structure shown in FIG. 10, for example. In this structure, a communication path 64 that communicates the pressure receiving liquid chambers 40A and 40B is formed in the partition wall 42, and moves into the pressure receiving liquid chamber 40A side part and the pressure receiving liquid chamber 40B side part in the communication path 64. A movable member 66 that can be partitioned is disposed. The moving member 66 is held by springs 68 from both sides along the communication path 64, and a force for returning to the initial position acts from the springs 68 when displaced from the initial position. Therefore, in this structure, when a pressure difference occurs between the pressure receiving liquid chambers 40A and 40B, the moving member 66 moves in the communication path 64, and this pressure difference is reduced. Of course, the pressure difference reducing means can be configured with a simple structure by forming the thin portion 42U shown in FIG.

  In the above description, the vibration isolator 12 has a structure in which the pressure receiving liquid chambers 40A and 40B are communicated with the sub liquid chamber 30 through the second restriction passage (second orifices 52A and 52B). Other structures may be employed. For example, instead of the second orifices 52A and 52B, a structure in which a direct communication path that directly communicates the pressure receiving liquid chambers 40A and 40B is provided as the second restriction path may be used. Furthermore, as the second restriction passage, the direct communication passage and the second orifices 52A and 52B of the embodiment of the present invention may be used in combination. In particular, when the pressure receiving liquid chambers 40A and 40B communicate with the sub liquid chamber 30, the pressure fluctuation of the pressure receiving liquid chamber can be more effectively absorbed by the expansion and contraction of the sub liquid chamber. Further, in the configuration in which the pressure-receiving liquid chambers 40A and 40B communicate with the sub liquid chamber, it is assumed that the dynamic spring constant in the high frequency region increases as described above due to the volume change of the sub liquid chamber. The Therefore, the present invention is particularly suitable for a configuration in which the pressure receiving liquid chambers 40A and 40B and the sub liquid chamber communicate with each other.

  In any configuration, in the vibration isolator 12 of the present embodiment, the thin wall portion 42U for releasing the pressure receiving liquid chambers 40A, 40B is formed in the partition wall 42 that divides the two pressure receiving liquid chambers 40A, 40B. In addition, since it is not necessary to perform processing such as forming a through hole in the inner cylinder 22, it can be manufactured at low cost. Further, in the configuration in which the movable rubber film or the like is provided in the through-hole of the inner cylinder 22, there is a great restriction on the shape and size of the movable rubber film), but when the thin wall portion 42U is provided in the partition wall 42 as in the present embodiment, the shape In addition, since the degree of freedom in size increases, it becomes possible to perform pressure relief in the axial direction more reliably.

12 Vibration isolator 14 Outer cylinder 16 Cover rubber 18 Diaphragm 20 Mounting member 22 Inner cylinder 24 Rubber elastic body 24B Rubber body section 24L Lid section 26 Orifice cylinder body 26E Orifice cylinder section 26D Orifice disk section 28 Main liquid chamber 30 Sub liquid chamber 32 Partition disk 34 Membrane 36 Orifice 38 Communication hole 40 Liquid chamber 40A, 40B Pressure receiving liquid chamber 42 Partition 42A Thick part 42U Thin part 44 Holding cylinder 46 Holding ring 48 Support plate 50 Groove 52A Orifice 54 Concave S Shaft center

Claims (5)

A first mounting member formed in a cylindrical shape and connected to one of the vibration generating portion and the vibration receiving portion;
A second mounting member connected to the other of the vibration generating portion and the vibration receiving portion and disposed on the inner peripheral side of the first mounting member;
An elastic body arranged between the first mounting member and the second mounting member and connecting the first mounting member and the second mounting member;
A partition member that constitutes a main liquid chamber in which a liquid is enclosed between the elastic member and an internal volume changes with elastic deformation of the elastic body,
A diaphragm member constituting a sub liquid chamber in which a liquid is enclosed between the partition member and an internal volume changes in accordance with a change in liquid pressure;
A first restriction passage that allows liquid to move between the main liquid chamber and the sub liquid chamber;
A recess which is provided in the elastic body and forms a liquid chamber between the first mounting member;
A partition that divides the liquid chamber into a plurality of pressure receiving liquid chambers arranged in a direction intersecting the axial direction of the first mounting member;
A second restriction passage that allows movement of liquid between the plurality of pressure receiving liquid chambers or between each of the pressure receiving liquid chambers and the sub liquid chamber;
A pressure difference reducing means for reducing a pressure difference between the plurality of pressure receiving liquid chambers provided in the partition;
A vibration isolator. The pressure difference reducing means is
It is constituted by a thin portion where the partition wall is locally thin,
The vibration isolator according to claim 1, wherein a portion of the partition other than the thin portion is a thick portion that is relatively thicker than the thin portion.   The vibration isolator according to claim 2, wherein the thick part is continuous from one end to the other end in the axial direction in the partition wall.   The vibration isolator according to claim 2 or 3, wherein the thin portion is formed in a circular shape when the partition is viewed from the front. The elastic body is a truncated cone-shaped conical portion that is extended from the second mounting member toward the partition member and gradually expanded in diameter;
A lid portion extending radially outward from the second mounting member on the opposite side of the partition member as seen from the conical portion and serving as a lid of the liquid chamber;
The vibration isolator according to any one of claims 1 to 4, further comprising:

Images