JP4671176B2 - Fluid filled vibration isolator - Google Patents

Description

  The present invention relates to a fluid-filled vibration damping device that obtains a vibration-proofing effect based on the flow action of an incompressible fluid sealed inside, and for example, a fluid that can be suitably used as an engine mount for automobiles, etc. The present invention relates to a sealed vibration isolator.

  Conventionally, as an anti-vibration device interposed between members constituting a vibration transmission system, a fluid-filled type anti-vibration using a vibration-proof effect based on a fluid action such as a resonance action of an incompressible fluid enclosed therein is used. Shaking devices are known. Such a vibration isolator generally connects a first mounting member and a second mounting member with a main rubber elastic body, while the main rubber elastic body forms a part of a wall portion, and a wall portion. Are formed with an equilibrium chamber composed of a flexible membrane, in which an incompressible fluid such as water is sealed in each of the pressure receiving chamber and the equilibrium chamber, and the pressure receiving chamber and the equilibrium chamber communicate with each other. An orifice passage is provided.

  In particular, in an engine mount for an automobile, in order to obtain an effective anti-vibration performance against vibrations in a plurality of frequency ranges such as low-frequency large-amplitude engine shake and high-frequency small-amplitude idling vibration, for example, Patent Literature 1 (Japanese Patent Laid-Open No. 57-009340), a hydraulic pressure absorption mechanism is also employed. Such a fluid pressure absorbing mechanism accommodates the movable plate so as to be displaceable by a predetermined amount in the plate thickness direction in a partition member that partitions the pressure receiving chamber and the equilibrium chamber, and balances the pressure receiving chamber with respect to the wall portions on both sides in the displacement direction of the movable plate. The structure is such that a communication hole is formed in each one of the chambers.

  By adopting such a hydraulic pressure absorption mechanism, fluctuations in pressure in the pressure receiving chamber when the orifice passage is substantially clogged when a vibration having a high frequency and a small amplitude than the tuning frequency range of the orifice passage is input can be reduced. Absorption can be reduced by allowing the pressure receiving chamber to escape to the equilibrium chamber based on the displacement. On the other hand, when low frequency large amplitude vibration is input, the movable plate overlaps the walls on both sides of the partition member in the displacement direction and the communication hole is closed, so that effective pressure fluctuation is generated in the pressure receiving chamber, and the orifice passage The amount of fluid flow through is secured. As a result, while maintaining the vibration-proofing effect of the orifice passage against low-frequency large-amplitude vibration, it is possible to maintain high vibration-proof performance by suppressing high dynamic springs when inputting high-frequency small-amplitude vibration. .

  By the way, in a conventional fluid-filled vibration isolator having an orifice passage and a fluid pressure absorbing mechanism as described above, if a large vibration load is input between the first mounting member and the second mounting member, There is a case where abnormal vibration or vibration is emitted from the vibration device. Specifically, in an automobile that employs a fluid-filled vibration isolator as an engine mount, when traveling on a wavy road, a speed breaker, etc., there is a risk of generating abnormal noise or impact that can be felt by the passenger in the passenger compartment. .

  The occurrence of such abnormal noise and vibration, when shocking vibration is input, the fluid flow between the pressure receiving chamber and the equilibrium chamber by the orifice passage and the pressure absorption of the pressure receiving chamber by the hydraulic pressure absorbing mechanism cannot follow, This is considered to be due to the fact that a significant negative pressure is instantaneously generated in the pressure receiving chamber, and bubbles that can be understood as cavitation are formed by liberation and evaporation of dissolved gas from the sealed fluid. Such bubbles generate a large impact when they grow and collapse as the negative pressure in the pressure receiving chamber increases. This is considered to be the water hammer pressure, propagated to the first mounting member and the second mounting member, and transmitted to the body of the automobile, thereby generating abnormal noise and impact as described above.

  In order to deal with such a problem, for example, in Patent Document 2 (Japanese Patent Laid-Open No. 61-171931), a hydraulic pressure absorbing partition rubber film (movable) is provided so as to partition the pressure receiving chamber and the equilibrium chamber. A structure in which a cut is formed in the film) has been proposed. In such a structure, when the pressure difference between the pressure receiving chamber and the equilibrium chamber becomes large, the partition rubber film is greatly elastically deformed so that the notch is opened. Thereby, it is possible to eliminate the pressure difference between the pressure receiving chamber and the equilibrium chamber.

  However, in such a structure proposed in Patent Document 1, not only when a negative pressure is generated in the pressure receiving chamber, but also when a positive pressure is generated, the partition rubber film is opened, so that at the time of vibration input, It becomes difficult to sufficiently obtain the relative pressure fluctuation between the pressure receiving chamber and the equilibrium chamber. As a result, there is a problem that it becomes difficult to secure the amount of fluid flow through the orifice passage, and the desired vibration-proofing effect by the orifice passage is not sufficiently exhibited.

  Moreover, there is a problem that it is difficult to set the opening condition of the cut in consideration of the characteristics and thickness dimensions of the partition rubber film, the size and shape of the formed cut, and the like only by forming the cut in the partition rubber film. That is, the notch is easily opened and the pressure fluctuation in the pressure receiving chamber is unnecessarily absorbed, and the vibration isolation effect by the orifice passage is hindered. There is a risk that it will be difficult to avoid the shocking negative pressure.

  In addition, due to repeated deformation of the partition rubber film, the incision progresses and becomes larger, or the characteristics of the partition rubber film change over time, so that the opening condition of the cut changes. Therefore, there is a problem that it is difficult not only to set the desired characteristic but also to obtain the set characteristic stably.

JP-A-57-009340 Japanese Patent Laid-Open No. 61-171931

  Here, the present invention has been made in the background as described above, and the problem to be solved is to quickly eliminate the excessive negative pressure generated in the pressure receiving chamber when a large vibration load is input. It is an object of the present invention to provide a fluid-filled vibration isolator having a novel structure that has a simple structure and high practicality, and that can suppress the occurrence of abnormal noise and impact that may be caused by cavitation.

  Hereinafter, the aspect of this invention made | formed in order to solve such a subject is described. In addition, the component employ | adopted in each aspect as described below is employable by arbitrary combinations as much as possible. Further, aspects or technical features of the present invention are not limited to those described below, but are described in the entire specification and drawings, or an invention that can be understood by those skilled in the art from those descriptions. It should be understood that it is recognized based on thought.

  That is, a feature of the present invention is that the first mounting member and the second mounting member are connected by the main rubber elastic body, and a pressure receiving chamber in which a part of the wall portion is configured by the main rubber elastic body, An orifice passage in which a part of the wall portion forms an equilibrium chamber composed of a flexible membrane, and the pressure receiving chamber and the equilibrium chamber are in communication with each other by enclosing an incompressible fluid in the pressure receiving chamber and the equilibrium chamber And a partition member that is supported by the second mounting member and divides the pressure receiving chamber and the equilibrium chamber, and accommodates the movable plate so as to be displaceable by a predetermined amount in the plate thickness direction and on both sides of the movable plate in the displacement direction. In the fluid-filled vibration isolator comprising a hydraulic pressure absorbing mechanism in which a communication hole that opens in each one of the pressure receiving chamber and the equilibrium chamber is formed in the wall portion, the movable plate is formed of an elastic material, At least the pressure receiving chamber side wall portion of the hydraulic pressure absorbing mechanism is formed of an elastic material. Accordingly, the wall and the movable plate are elastically deformed so as to protrude toward the pressure receiving chamber in a state where the movable plate is overlapped with the wall on the pressure receiving chamber side in the hydraulic pressure absorbing mechanism. It is to be able to be harassed.

  In a fluid-filled vibration isolator having a structure according to the present invention, when an input of low-frequency large-amplitude vibration such as an engine shake, for example, an orifice passage is based on a relative pressure fluctuation caused between a pressure receiving chamber and an equilibrium chamber. The anti-vibration effect is exhibited based on the fluid action such as the resonance action of the fluid that causes the fluid to flow. At that time, in the hydraulic pressure absorption mechanism, the displacement of the movable plate is limited by contact with the wall portions on the pressure receiving chamber side and the equilibrium chamber side, so that it does not function sufficiently, and the pressure fluctuation in the pressure receiving chamber is effectively generated. Will be. On the other hand, for example, when high-frequency small-amplitude vibration such as idling vibration or running-over noise is input, the flow resistance of the orifice passage is remarkably increased and becomes substantially closed. However, in the hydraulic pressure absorption mechanism, the movable plate is on the pressure-receiving chamber side. By allowing displacement between the wall portion on the equilibrium chamber side, the pressure fluctuation of the pressure receiving chamber is absorbed so as to be released to the equilibrium chamber, and the deterioration of the vibration proof performance due to the remarkably high dynamic spring is avoided, Good vibration-proof performance will be exhibited. In particular, when a small amplitude vibration is input, the movable plate displaces between the pressure receiving chamber side wall and the equilibrium chamber side wall in an unconstrained state, so that an extremely effective anti-vibration performance improvement effect is exhibited. It is done.

  Here, in particular, in the fluid filled type vibration damping device according to the present invention, when an excessive and shocking vibration load is input, when a sudden negative pressure is generated in the pressure receiving chamber, the pressure receiving chamber and the equilibrium chamber are notable. Due to the pressure difference, the movable plate constituting the hydraulic pressure absorbing mechanism comes into contact with and overlaps the wall portion on the pressure receiving chamber side. As a result, the communication hole formed in the wall portion on the pressure receiving chamber side in the hydraulic pressure absorbing mechanism is in a closed state, but both the movable plate and the pressure receiving chamber side wall portion that overlap each other are both made of an elastic material in the present invention. Therefore, the movable plate and the pressure receiving chamber side wall portion are overlapped with each other so that the movable plate and the pressure receiving chamber side wall are convex toward the pressure receiving chamber side based on the relative pressure difference between the pressure receiving chamber and the equilibrium chamber. It will swell and elastically deform.

  In this way, the negative pressure in the pressure receiving chamber is reduced or eliminated by bulging toward the pressure receiving chamber while the movable plate and the pressure receiving chamber side wall overlap with each other. As a result, cavitation in the pressure receiving chamber is effectively avoided. Can be done.

  In addition, the pressure receiving chamber side wall portion in the hydraulic pressure absorption mechanism is formed of an elastic material, but when normal high frequency small amplitude vibration is input, fluid flow through the communication hole formed in the pressure receiving chamber side wall portion is allowed. Since the communication hole avoids that a large pressure is exerted on the pressure receiving chamber side wall itself, it is considered that there are almost no problems caused by forming the pressure receiving chamber side wall portion with an elastic material.

  Therefore, in the fluid filled type vibration damping device according to the present invention, the vibration damping effect against the low frequency large amplitude vibration based on the fluid flow action through the orifice passage, and the vibration damping effect against the high frequency small amplitude amplitude by the hydraulic pressure absorption mechanism, Cavitation can be reduced or avoided based on the elastic deformation of the movable plate and the pressure receiving chamber side wall constituting the hydraulic pressure absorbing mechanism while ensuring good in both cases. This makes it possible to effectively reduce or eliminate abnormal noise and impact that are thought to be caused by cavitation during input.

  In addition, the present invention can be easily realized only by changing the material of the members and parts constituting the conventional hydraulic pressure absorption mechanism to an appropriate elastic material, and therefore, special parts, special parts, and manufacturing processes are required. Therefore, there is no problem that the size and weight of the vibration isolator are increased, and therefore, there is an advantage that it can be practically used.

  By the way, in the present invention as described above, for example, the movable plate made of an elastic material is made smaller than the wall portion on the pressure receiving chamber side made of an elastic material in the hydraulic pressure absorbing mechanism, A configuration in which the entire movable plate overlaps with the pressure receiving chamber side wall portion formed of an elastic material is preferably employed.

  Thus, by making the movable plate smaller than the portion formed of the elastic material in the pressure receiving chamber side wall, the movable plate overlaps the pressure receiving chamber side wall in the hydraulic pressure absorbing mechanism when an excessive vibration load is input. The elastic deformation toward the pressure receiving chamber as a whole is easily generated, and the effect of avoiding cavitation can be exhibited more advantageously. Further, since the entire movable plate is elastically deformed in a state where it overlaps the pressure receiving chamber side wall formed of an elastic material, local bending and strain concentration on the movable plate can be avoided, and Durability can also be improved.

  That is, in the present invention, in the hydraulic pressure absorbing mechanism, it is desirable that the entire portion of the pressure receiving chamber side wall where the movable plates overlap is formed of an elastic material. For example, the entire pressure receiving chamber side wall is formed of an elastic material. Such a configuration is also preferably employed.

  In the present invention, for example, a configuration in which the wall portion on the equilibrium chamber side in the hydraulic pressure absorption mechanism is formed of a hard material is suitably employed.

  In this way, by adopting the equilibrium chamber side wall portion made of a hard material in the hydraulic pressure absorption mechanism, it is based on the elastic deformation of the equilibrium chamber side wall portion and the movable plate when the positive pressure is generated without the problem of cavitation in the pressure receiving chamber. The pressure absorbing action of the pressure receiving chamber is suppressed. As a result, the pressure fluctuation of the pressure receiving chamber at the time of inputting the low frequency large amplitude vibration is more effectively generated, and the vibration isolation effect by the orifice passage is more effectively exhibited.

  On the other hand, in the present invention, instead of such a mode in which the equilibrium chamber side wall portion is formed of a hard material, a mode in which the equilibrium chamber side wall portion in the hydraulic pressure absorption mechanism is formed of an elastic material can also be adopted. It is.

  In this way, by adopting the equilibrium chamber side wall portion made of an elastic material in the hydraulic pressure absorption mechanism, the movable plate is moved to the equilibrium chamber side wall portion based on the relative pressure difference between the pressure receiving chamber and the equilibrium chamber when large amplitude vibration is input. It is possible to reduce the hitting sound and impact when hitting. In the present invention, in order to achieve the same object, for example, instead of or in addition to forming the equilibrium chamber side wall portion with an elastic material, at least the contact surface between the movable plate and the equilibrium chamber side wall portion is used. On the other hand, it is also effective to form an elastic protrusion for buffering.

  Further, as described above, when the equilibrium chamber side wall portion made of an elastic material is employed in the hydraulic pressure absorbing mechanism, an aspect in which the rigidity of the equilibrium chamber side wall portion is larger than the rigidity of the pressure receiving chamber side wall portion is also preferably employed. .

  As a result, in the pressure receiving chamber side wall portion, elastic deformation is allowed to the pressure receiving chamber side relatively easily in a state where the movable plates are overlapped, thereby effectively preventing cavitation in the pressure receiving chamber, and the equilibrium chamber side wall portion. Thus, it is possible to reduce the occurrence of a hitting sound or the like when the movable plate strikes while suppressing the pressure absorption of the pressure receiving chamber due to the elastic deformation at the time of inputting the low frequency large amplitude vibration. In addition, the elasticity of the pressure receiving chamber side wall and the equilibrium chamber side wall can be set by, for example, changing the material of the elastic material to be formed, adjusting the thickness of the wall, or the wall formed by the elastic material. This can be done by embedding or fixing a deformation restraining material such as a canvas, a synthetic resin film, a partial reinforcing plate, or the like.

In the present invention, for example, configuration in which the spring rigidity of the walls of the pressure receiving chamber side in front Symbol hydraulic pressure absorbing mechanism formed of an elastic material is greater than the spring stiffness of the movable plate, it is preferably employed The This suppresses excessive displacement of the pressure-receiving chamber side wall during normal low-frequency large-amplitude vibration or high-frequency small-amplitude vibration input, making the desired vibration-proofing effect more stable in the orifice passage and hydraulic pressure absorption mechanism. Can be demonstrated.

  As described above, in the fluid-filled vibration isolator having a structure according to the present invention, the generation of excessive negative pressure in the pressure receiving chamber can be quickly reduced or eliminated by skillfully utilizing the hydraulic pressure absorption mechanism to prevent cavitation. Therefore, it is possible to solve problems such as abnormal noise and impact caused by cavitation with a simple structure.

  First, the engine mount 10 for motor vehicles as 1st embodiment of this invention is shown by FIGS. 1-2. In the engine mount 10, a first mounting member 12 as a first mounting member and a second mounting member 14 as a second mounting member are in the input direction of the main vibration to be shaken in FIG. They are spaced apart from each other in the vertical direction and have a structure that is elastically connected by interposing a main rubber elastic body 16 therebetween.

  Although not clearly shown in the drawings, the first mounting bracket 12 is mounted on the power unit side and the second mounting bracket 14 is mounted on the body side, so that the power unit is supported by vibration isolation against the body. It has become.

  In such a mounting state, the power unit weight is exerted as an initial load between the first mounting bracket 12 and the second mounting bracket 14, and the main rubber elastic body 16 is elastically deformed. The first mounting bracket 12 and the second mounting bracket 14 are positioned close to each other by a predetermined amount. Further, under such a mounting state, main vibrations to be vibrated are input in a substantially vertical direction in FIG. 1, and the first mounting bracket 12 and the second mounting bracket 14 are relatively displaced in the approach / separation direction. It is supposed to be squeezed. In the following description, the vertical direction means the vertical direction in FIG. 1 in principle.

  More specifically, the first mounting bracket 12 has a circular flat plate shape, and a first mounting bolt 18 that protrudes upward is fixed to the center portion. Then, the first mounting bracket 12 is mounted and fixed to a power unit (not shown) by the first mounting bolt 18.

  On the other hand, the second mounting bracket 14 is formed by a cylindrical bracket 20 and a bottom bracket 22 with a deep bottomed cylindrical shape as a whole.

  The cylindrical metal fitting 20 has a large-diameter cylindrical shape, with the stepped portion 24 formed in the axially intermediate portion sandwiching the stepped portion 24, the axially upper side is a small-diameter portion 26, and the axially lower side is a large-diameter. A caulking portion 30 is integrally formed at the opening edge on the large diameter portion 28 side. The bottom metal fitting 22 has a shallow bottomed cylindrical shape, and a flange portion 32 that extends outward in the radial direction is integrally formed at the periphery of the opening.

  Then, the cylindrical fitting 20 is coaxially overlapped on the opening side of the bottom fitting 22, and the caulking portion 30 of the tubular fitting 20 is caulked and fixed to the flange portion 32 of the bottom fitting 22. A metal fitting 14 is configured. Note that second mounting bolts 36, 36 projecting downward are fixed to the bottom wall portion 34 of the bottom metal member 22, and the second mounting bolts 36, 36 provide a second mounting bolt. The metal fitting 14 is attached and fixed to a body (not shown).

  Moreover, the main rubber elastic body 16 has a substantially truncated cone shape as a whole, and a recess 19 is formed in the opening portion on the lower side in the axial direction. Further, the main rubber elastic body 16 has a first mounting bracket 12 vulcanized and bonded to the end surface on the small diameter side, and a second mounting bracket 14 is formed on the outer peripheral surface of the large diameter end portion. The small-diameter portion 26 of the tubular fitting 20 to be vulcanized is bonded. In short, the main rubber elastic body 16 is formed as an integrally vulcanized molded product 38 having the first mounting bracket 12 and the cylindrical bracket 20. Further, the main rubber elastic body 16 is vulcanized and bonded to the small-diameter portion 26 of the tubular metal fitting 20, whereby the upper opening (opening on the small-diameter portion 26 side) of the tubular metal fitting 20 is fluid-tightly closed. .

  Furthermore, a partition member 40 and a diaphragm 42 as a flexible film are assembled to the integrally vulcanized molded product 38 of the main rubber elastic body 16 formed so as to include the first mounting member 12 and the cylindrical member 20 as described above. It has been.

  The diaphragm 42 is formed of a thin rubber film, and has a shape that swells upward with a sufficient slack in the central portion, so that deformation is easily allowed. An annular support fitting 44 having an annular shape is vulcanized and bonded to the outer peripheral edge of the diaphragm 42.

  Then, the annular support fitting 44 is fitted into the large diameter portion 28 of the tubular fitting 20 constituting the second mounting fitting 14, and between the stepped portion 24 of the tubular fitting 20 and the flange portion 32 of the bottom fitting 22. The two mounting brackets 14 are assembled by being caulked and fixed together with the flange portion 32 by the caulking portion 30 of the cylindrical metal fitting 20. The caulking fixed portion by the caulking portion 30 includes a seal rubber layer 46 integrally formed with the main rubber elastic body 16 on the stepped portion 24 of the cylindrical metal fitting 20 and a seal rubber integrally formed with the diaphragm 42 on the annular support metal fitting 44. Layer 48 is fluid tightly sealed.

  Thereby, the opening part (opening part by the side of the large diameter part 28) of the axial direction lower side of the cylinder metal fitting 20 is fluid-tightly obstruct | occluded by the diaphragm 42. FIG. As a result, a fluid chamber 50 that is fluid-tightly partitioned from the outside is formed between the opposing surfaces of the main rubber elastic body 16 and the diaphragm 42 that are opposed to each other inside the cylindrical metal fitting 20. The fluid chamber 50 is filled and filled with an incompressible fluid such as water, alkylene glycol, polyalkylene glycol, or silicone oil.

  Further, the partition member 40 is disposed in the fluid chamber 50 in the accommodated state. The partition member 40 has a substantially disk shape as a whole, and is disposed so as to spread in the direction perpendicular to the axis of the second mounting bracket 14, and the outer peripheral portion is fixed by the second mounting bracket 14. Is supported.

  Thus, when the partition member 40 is disposed in the fluid chamber 50, the fluid chamber 50 is vertically divided into two by the partition member 40. And above the partition member 40, the pressure receiving chamber 52 in which a part of the wall portion is composed of the main rubber elastic body 16 is formed. On the other hand, below the partition member 40, an equilibrium chamber 54 in which a part of the wall portion is constituted by the diaphragm 42 is formed.

  That is, the pressure receiving chamber 52 is vibrated based on the elastic deformation of the main rubber elastic body 16 when vibration is input, thereby causing pressure fluctuation. On the other hand, in the equilibrium chamber 54, the volume change is easily allowed based on the elastic deformation of the diaphragm 42 constituting the wall portion, and the pressure fluctuation is quickly absorbed.

  Here, the partition member 40 is configured to include upper and lower plate fittings 56 and 58 each having a thin and substantially disk shape that are superposed on each other. The upper and lower plate fittings 56 and 58 are sandwiched between the stepped portion 24 of the second mounting fitting 14 and the annular support fitting 44 of the diaphragm 42 at the outer peripheral edge portion where the upper and lower plate fittings are superposed in close contact with each other. Thus, together with the annular support fitting 44, the second attachment fitting 14 is caulked and fixed by the caulking portion 30. Thereby, the partition member 40 is arrange | positioned in the formation part of the level | step-difference part 24 of the cylindrical metal fitting 20 which comprises the 2nd attachment metal fitting 14 in the state which spreads in the direction orthogonal to an axis.

  Further, the upper and lower plate fittings 56 and 58 have their central portions protruding upward in a circular plate shape, and the outer diameter dimensions of the circular plate-like protruding portions of the two plate fittings 56 and 58 are different from each other. Thus, an orifice passage 60 is formed between the overlapping surfaces of the two plate fittings 56 and 58 so that the outer peripheral portion extends in the circumferential direction by a predetermined length of one turn or less.

  One end of the orifice passage 60 is connected to the recess 19 through a communication hole 62 formed in the upper plate fitting 56, and the other end of the orifice passage 60 is connected to the lower plate fitting 58. It is opened to the outside of the recess 19 through the communication hole 63 formed in the bottom. Accordingly, the orifice passage 60 allows the pressure receiving chamber 52 and the equilibrium chamber 54 to communicate with each other. Further, particularly in the present embodiment, a low frequency large wave equivalent to an engine shake or the like is based on the resonance action of the fluid that can flow through the orifice passage 60 by appropriately adjusting the passage length and the passage sectional area of the orifice passage 60. It is tuned so as to exhibit a damping effect against amplitude vibration.

  A shallow circular recess 64 is formed in the central portion of the lower plate metal fitting 58. Further, an appropriate number of equilibrium chamber side communication holes 68 penetrating in the thickness direction are formed in the bottom wall portion 66 of the circular recess 64.

  Furthermore, a through hole 70 is formed in the central portion of the upper plate metal member 56 with a diameter that substantially corresponds to the circular recess 64 of the lower plate metal member 58 described above. Further, an annular flange 72 rising upward is integrally formed at the opening peripheral edge of the through hole 70 in the upper plate metal fitting 56. A disc-shaped rubber wall plate 74 is disposed in the through hole 70, and the outer peripheral edge portion thereof is vulcanized and bonded to the annular flange 72 of the upper plate metal piece 56. In short, the rubber wall plate 74 extends in the direction perpendicular to the axis within the through hole 70 of the upper plate metal piece 56 and is disposed so as to cover the through hole 70. Further, an appropriate number of pressure receiving chamber side communication holes 76 penetrating in the thickness direction are formed in the rubber wall plate 74.

  As a result, in the central portion of the upper and lower plate fittings 56, 58 surrounded by the orifice passage 60, the opening of the circular recess 64 of the lower plate fitting 58 is a rubber wall plate 74 fixed to the upper plate fitting 56. By being covered, a circular accommodation space 78 is formed which extends with a substantially constant gap dimension in the direction perpendicular to the axis between the axially opposed surfaces of the bottom wall portion 66 of the circular recess 64 and the rubber wall plate 74. . As is clear from this, in the present embodiment, the pressure receiving chamber side wall portion of the accommodation space 78 is constituted by the rubber wall plate 74 made of a rubber elastic body, while the equilibrium chamber side wall portion is made of a rigid lower plate metal 58. The bottom wall portion 66 is formed.

  A movable plate 80 is accommodated in the accommodation space 78. The movable plate 80 has a disc shape and is formed of a rubber elastic body. As shown in FIG. 2, the movable plate 80 has a thickness dimension between the upper and lower walls of the accommodation space 78, that is, the bottom wall 66 of the circular recess 64 and the rubber wall plate 74. It is made smaller than the distance between opposing surfaces. Furthermore, the outer diameter of the movable plate 80 is smaller than the inner diameter of the accommodation space 78, that is, the inner diameter of the circular recess 64.

  Thereby, the movable plate 80 is within the allowable displacement range limited by the contact between the rubber wall plate 74 constituting the upper and lower wall portions and the bottom wall portion 66 of the circular recess 64 in the accommodation space 78. Therefore, displacement in the plate thickness direction is allowed. In addition, the movable plate 80 is separated from the upper and lower plate fittings 56, 58, the rubber wall plate 74, and the like between the allowable displacements, and is displaced in the plate thickness direction without being subjected to displacement resistance by them. It is supposed to be.

  The movable plate 80 is configured such that the pressure in the pressure receiving chamber 52 is exerted on the upper surface through the pressure receiving chamber side communication hole 76, and the pressure in the equilibrium chamber 54 is exerted on the lower surface through the equilibrium chamber side communication hole 68. It is like that. Therefore, at the time of vibration input between the first mounting bracket 12 and the second mounting bracket 14, the movable plate 80 is moved based on the relative pressure fluctuation caused between the pressure receiving chamber 52 and the equilibrium chamber 54. In the housing space 78, it is displaced in the plate pressure direction.

  Thus, when high frequency small amplitude vibrations such as idling vibrations and running noises that are higher than the tuning frequency of the orifice passage 60 are input, the orifice passage 60 is substantially closed, but the pressure receiving chamber 52 The generated pressure fluctuation is absorbed so as to escape to the equilibrium chamber 54 based on the displacement of the movable plate 80 in the accommodation space 78. As a result, it is possible to avoid a significant deterioration of the dynamic spring characteristics associated with the substantial closing of the orifice passage 60 and to exhibit a good vibration isolation performance. As is apparent from this, in this embodiment, the movable plate 80 is housed in the housing space 78 formed by the upper and lower metal plates 56 and 58 and the rubber wall plate 74 so as to be displaceably accommodated. The mechanism is configured.

  In this state, the rubber wall plate 74 constituting the upper side wall portion of the accommodation space 78 is formed of a rubber elastic body. However, the fluid flow through the pressure receiving chamber side communication hole 76 is allowed, so that the rubber wall No great pressure is exerted on the plate 74 itself. Therefore, a problem caused by elastic deformation of the rubber wall plate 74 does not become a problem.

  Further, when low-frequency large-amplitude vibration such as an engine shake that requires an anti-vibration effect by the orifice passage 60 is input, the amount of displacement of the movable plate 80 is the bottom of the circular recess 64 constituting the upper and lower walls of the accommodation space 78. Since it is limited by contacting the wall portion 66 and the rubber wall plate 74, the pressure fluctuation is not absorbed by the displacement of the movable plate 80. Therefore, the relative pressure fluctuation between the pressure receiving chamber 52 and the equilibrium chamber 54 is effectively generated, and the vibration isolation effect based on the fluid flow through the orifice passage 60 is effectively exhibited.

  Further, when the engine mount 10 having the above-described structure is mounted and an excessive vibration load is impacted when the vehicle steps over, etc., an excessive negative pressure is generated in the pressure receiving chamber 52. There is.

  In that case, an extremely large pressure difference is induced between the pressure receiving chamber 52 and the equilibrium chamber 54, and this pressure difference is also exerted on the partition member 40. Here, in particular, when an excessive negative pressure is generated in the pressure receiving chamber 52, the entire movable plate 80 comes into contact with and overlaps the rubber wall plate 74 by the negative pressure. Further, since the negative pressure in the pressure receiving chamber 52 cannot be absorbed by only the displacement of the movable plate 80 in the accommodation space 78, the pressure receiving chamber 52 is further separated from the rubber wall plate 74 and the movable plate 80 that overlap each other. Negative pressure is applied from the side. At this time, the communication hole 62 of the rubber wall plate 74 is substantially cut off due to the movable plate 80 being overlapped from the lower surface, so that a large negative pressure is exerted on the rubber wall plate 74 as well. Acts on the side.

  As a result, the rubber wall plate 74 formed of a rubber elastic body is elastically deformed so as to bulge and protrude toward the pressure receiving chamber 52 as a whole while overlapping with the movable plate 80 formed of a rubber elastic body. Is allowed and is elastically deformed as such. The negative pressure in the pressure receiving chamber 52 can be quickly reduced or eliminated by the displacement accompanying the elastic deformation toward the pressure receiving chamber 52 as a whole when the rubber wall plate 74 and the movable plate 80 overlap each other.

  Therefore, even when an excessive vibration load is input, generation of excessive negative pressure in the pressure receiving chamber 52 can be avoided, and cavitation is prevented, so that abnormal noise and vibration that may be caused by generation of bubbles accompanying cavitation are prevented. The occurrence of this can be effectively prevented.

  Further, particularly in this embodiment, the pressure receiving chamber side wall portion of the accommodation space 78 of the movable plate 80 is constituted by the rubber wall plate 74 made of a rubber elastic body, whereas the equilibrium chamber side wall portion is a rigid lower plate. Since the metal plate 58 is configured, even when a large positive pressure generated in the pressure receiving chamber 52 is exerted on the movable plate 80 and the movable plate 80 overlaps the lower plate metal plate 58, the displacement of the movable plate 80 is further increased. Be blocked. Therefore, for example, the positive pressure induced in the pressure receiving chamber 52 at the time of vibration input such as engine shake is avoided from being unnecessarily absorbed by the hydraulic pressure absorbing mechanism, and low frequency large amplitude vibration such as engine shake is avoided. , The relative pressure fluctuation is efficiently generated between the pressure receiving chamber 52 and the equilibrium chamber 54, and the amount of fluid flow through the orifice passage 60 is advantageously ensured. The anti-vibration effect by the squeezed fluid is effectively exhibited.

  It is desirable that the movable plate 80 is set to be easily elastically deformed as compared with the rubber wall plate 74. As a result, problems such as a decrease in the vibration isolation effect due to the orifice passage 60 due to unnecessary elastic deformation of the rubber wall plate 74 are avoided. Further, the elastic deformation that bulges toward the pressure receiving chamber 52 in a state where the movable plate 80 overlaps the rubber wall plate 74 is prevented from being unnecessarily limited by the movable plate 80. In addition, when the movable plate 80 is displaced, it is possible to reduce the impact sound and impact when the movable plate 80 comes into contact with the inner surface of the accommodation space 78. In particular, in order to reduce the hitting sound or the like of the movable plate 80, for example, as shown in the present embodiment, an elastic protrusion for buffering is provided on the contact surface of the movable plate 80 with respect to the inner surface of the accommodation space 78. It is also effective to form it.

  As mentioned above, although embodiment of this invention was explained in full detail, this is an illustration to the last, Comprising: This invention is not interpreted limitedly by the specific description in this embodiment.

  For example, as shown in FIG. 3, in the hydraulic pressure absorbing mechanism, the lower wall portion of the accommodation space 78 in which the movable plate 80 is disposed is replaced with a rubber wall plate (upper side) constituting the upper wall portion in the embodiment. Similarly to the rubber wall plate 74, the lower rubber wall plate 82 made of a rubber elastic body may be used. As a result, it is possible to mitigate the impact sound and impact at the time of contact with the lower rubber wall plate 82 of the movable plate 80.

  In the embodiment shown in FIG. 3, the upper rubber wall plate 74 and the lower rubber wall plate 82 have different actions and purposes, so that the rubber material, thickness dimension, and the like are different from each other. The spring characteristics such as spring stiffness may be different. Specifically, for example, by making the rigidity of the lower rubber wall plate 82 greater than the rigidity of the upper rubber wall plate 74, the upper rubber wall plate 74 may be more easily elastically deformed than the lower rubber wall plate 82. Good. Thereby, the upper rubber wall plate 74 and the movable plate 80 are overlapped with the lower rubber wall plate 82 while advantageously ensuring the effect of preventing cavitation based on elastic deformation such that the upper rubber wall plate 74 and the movable plate 80 swell toward the pressure receiving chamber 52 side. It is possible to suppress a decrease in the orifice effect due to the positive pressure absorbing action of the pressure receiving chamber 52 due to elastic deformation that bulges toward the equilibrium chamber 54 side in a state where the plates 80 overlap.

  Further, as shown in FIG. 4, in the hydraulic pressure absorbing mechanism, the upper rubber wall plate 84 of the accommodation space 78 in which the movable plate 80 is disposed may be formed with a size smaller than that of the movable plate 80. good. As a result, it is possible to adjust the spring characteristics of the upper rubber wall plate 74 harder by setting the effective area of the upper rubber wall plate 84 small while ensuring the movable effective area of the movable plate 80 sufficiently. Thus, the degree of freedom in design and the degree of freedom in tuning can be improved.

The longitudinal section explanatory view showing the engine mount as one embodiment of the present invention. The principal part expansion explanatory drawing of the engine mount shown by FIG. The principal part expansion explanatory view corresponding to Drawing 2 in the engine mount as another embodiment of the present invention. The principal part expansion explanatory view corresponding to Drawing 2 in the engine mount as still another embodiment of the present invention.

Explanation of symbols

10 engine mount, 12 first mounting bracket, 14 second mounting bracket, 40
Partition member, 42 Diaphragm, 52 Pressure receiving chamber, 54 Equilibrium chamber, 56 Upper plate fitting, 58 Lower plate fitting, 60 Orifice passage, 64 Circular recess, 66 Bottom wall portion, 68
Equilibrium chamber side communication hole, 74 Rubber wall plate, 76 Pressure receiving chamber side communication hole, 78 Storage space, 80 Movable plate, 82 Lower rubber wall plate, 84 Upper rubber wall plate

Claims (6)

The first mounting member and the second mounting member are connected by a main rubber elastic body, and a pressure receiving chamber in which a part of the wall part is configured by the main rubber elastic body and a part of the wall part is a flexible film. Forming an equilibrated chamber, enclosing an incompressible fluid in the pressure receiving chamber and the equilibrium chamber to provide an orifice passage for communicating the pressure receiving chamber and the equilibrium chamber with each other, and the second mounting member In the partition member that is supported and partitions the pressure receiving chamber and the equilibrium chamber, the movable plate is accommodated so as to be displaceable by a predetermined amount in the plate thickness direction, and the pressure receiving chamber and the equilibrium chamber are disposed on the wall portions on both sides in the displacement direction of the movable plate. In a fluid-filled vibration isolator that constitutes a hydraulic pressure absorbing mechanism in which a communication hole that opens in one of the above is formed,
The movable plate is formed of an elastic material, and at least the pressure receiving chamber side wall portion of the hydraulic pressure absorption mechanism is formed of an elastic material, whereby the pressure plate chamber side wall portion of the hydraulic pressure absorption mechanism is formed. A fluid-filled type vibration damping device, wherein the wall portion and the movable plate can be elastically deformed so as to protrude toward the pressure receiving chamber side in a state where the movable plate is overlaid.   The movable plate made of an elastic material is made smaller than the wall on the pressure receiving chamber side made of an elastic material in the hydraulic pressure absorbing mechanism, and the entire movable plate is made of an elastic material. The fluid filled type vibration damping device according to claim 1, wherein the fluid filled type vibration damping device overlaps with a wall portion on the pressure receiving chamber side.   The fluid-filled vibration isolator according to claim 1 or 2, wherein a wall portion on the equilibrium chamber side in the hydraulic pressure absorbing mechanism is formed of a hard material.   The fluid-filled vibration isolator according to claim 1 or 2, wherein a wall portion on the equilibrium chamber side in the hydraulic pressure absorbing mechanism is formed of an elastic material.   5. The fluid filled type vibration damping device according to claim 4, wherein the rigidity of the wall portion on the equilibrium chamber side in the hydraulic pressure absorption mechanism is larger than the rigidity of the wall portion on the pressure receiving chamber side. Fluid-filled according to the spring stiffness of the wall of the pressure receiving chamber side in any one of claims 1 to 5 and greater than the spring stiffness of the movable plate prior SL hydraulic pressure absorbing mechanism formed of an elastic material Anti-vibration device.

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