JP4792414B2 - Fluid filled vibration isolator - Google Patents

Description

The present invention relates to an anti-vibration device used as, for example, an automobile engine mount and the like, and more particularly, a fluid-filled anti-vibration device that obtains an anti-vibration effect by utilizing the flow action of an incompressible fluid enclosed therein. It is about.

  2. Description of the Related Art Conventionally, a fluid-filled vibration isolator is known as a type of anti-vibration coupling body or anti-vibration support body that is mounted between members constituting a vibration transmission system. Such a vibration isolator generally includes a pressure receiving chamber in which a first mounting member and a second mounting member are connected by a main rubber elastic body, a part of the wall portion is configured by the main rubber elastic body, and deformation. An equilibrium chamber in which a part of the wall portion is configured by an easy flexible film is provided, and an incompressible fluid is sealed in the pressure receiving chamber and the equilibrium chamber. The pressure receiving chamber and the equilibrium chamber are communicated with each other based on a relative pressure fluctuation caused between the pressure receiving chamber and the equilibrium chamber when vibration is input between the first mounting member and the second mounting member. The vibration isolating effect can be exhibited based on the resonance action of the fluid that can flow through the orifice passage formed as described above.

  By the way, the anti-vibration effect based on the resonance action of the incompressible fluid that is caused to flow through the orifice passage can hardly be exhibited effectively only in a specific frequency range that has been tuned in advance. Therefore, in order to improve the anti-vibration performance by avoiding remarkably high dynamic spring at the time of vibration input particularly in the frequency range higher than the tuning frequency range of the orifice passage, for example, as disclosed in Patent Document 1 or 2, A hydraulic pressure absorption mechanism using a movable plate has been proposed. In general, this hydraulic pressure absorption mechanism has a structure in which a movable rubber film is disposed at the central portion of a partition member that partitions the pressure receiving chamber and the equilibrium chamber so as to be minutely displaceable. In this movable rubber film, the pressure in the heavy pressure chamber is exerted on one surface and the pressure in the equilibrium chamber is exerted on the other surface by the pressure receiving chamber side window portion and the equilibrium chamber side window portion formed on the partition member. It is like that.

  Then, by exerting the low dynamic spring effect of the movable rubber film based on the pressure difference between the pressure receiving chamber and the equilibrium chamber, the movable rubber film is slightly displaced, so that the minute pressure fluctuation of the pressure receiving chamber at the time of vibration input in the high frequency range To be absorbed. On the other hand, at the time of vibration input in the low frequency range in which the orifice passage is tuned, the amplitude of the vibration is large, so that the movable rubber film is brought into contact with and overlapped with the equilibrium chamber side window, for example. Is substantially occluded. As a result, the pressure absorption of the pressure receiving chamber by the hydraulic pressure absorbing mechanism is avoided, and the relative pressure fluctuation between the pressure receiving chamber and the equilibrium chamber is effectively generated, and the fluid flow through the orifice passage between the two chambers A sufficient amount is ensured so that the vibration isolation effect by the orifice passage is exhibited.

  However, in such a hydraulic pressure absorption mechanism, the movable rubber film hits the partition member due to a minute displacement of the movable rubber film, and this impact is likely to be generated as abnormal noise. there were.

  In order to cope with such a problem, for example, Patent Document 1 proposes a structure in which a small lip-shaped protrusion is integrally formed on the surface of the movable rubber film and the impact at the time of hitting is absorbed by the small protrusion. Has been. However, with the structure as described in Patent Document 1, a sufficient noise reduction effect has not yet been obtained.

  In Patent Document 2, a structure is proposed in which the outer peripheral edge of the movable rubber film is constricted and constrained to limit the displacement amount of the movable rubber film and prevent the partition member from being hit. . However, even with the structure as described in Patent Document 3, generation of abnormal noise has been pointed out, and a sufficient noise reduction effect has not been obtained, and further countermeasures have been desired.

JP-A 64-49731 JP-A-6-307491

  Here, the present invention has been made in the background as described above, and the problem to be solved is to suppress the generation of abnormal noise caused by hitting the movable rubber film against the partition member. An object of the present invention is to provide a fluid-filled vibration isolator having a novel structure.

  As a result of the inventor's repeated experiments and examinations on the above-described problems, the generation of abnormal noise is caused by striking the partition member when the large rubber vibration is simply input and the movable rubber film is excessively displaced. The knowledge that it was not caused only by the hit was obtained.

  That is, in a fluid-filled vibration isolator equipped with a movable rubber film, the movable rubber film resonates and moves greatly even when vibration is input in a high frequency range, and the hitting against the partition member occurs continuously. It has been found that sound is produced.

  As described above, the present inventor has newly found out that the occurrence of abnormal noise is caused by the resonance of the movable rubber film, and completes the present invention based on such new knowledge. Has been reached.

  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, according to the first aspect of the present invention, the first mounting member and the second mounting member are connected by the main rubber elastic body, and a part of the wall portion is configured by the main rubber elastic body so that pressure is applied at the time of vibration input. A pressure receiving chamber in which fluctuations are generated and an equilibrium chamber in which a part of the wall portion is made of a flexible film and volume change is allowed are arranged on both sides of the partition member supported by the second mounting member. Forming and sealing the incompressible fluid in the pressure receiving chamber and the equilibrium chamber, and providing a first orifice passage on the outer periphery of the partition member to communicate the pressure receiving chamber and the equilibrium chamber with each other. A movable rubber film is disposed in the central portion of the movable rubber film, and a pressure receiving chamber side window that applies the pressure of the pressure receiving chamber to one surface of the movable rubber film and a pressure of the equilibrium chamber to the other surface of the movable rubber film. A fluid-filled vibration isolator having a pressure absorbing mechanism provided on the partition member with an equilibrium chamber side window In, along with the one of the outer peripheral edge and the central portion of the moveable rubber film by the partition member allowed to clamp the holding, to form the second orifice passage between the pressure receiving chamber-side window by the equilibrium chamber-side window, movable The natural frequency of the elastic deformation of the movable rubber film is set on the high frequency side as compared with the resonance frequency of the fluid that flows through the second orifice passage based on the elastic deformation of the rubber film . The opening area of the pressure receiving chamber side window is set within a range of 1/3 to 1/2 of the area of the movable part in the movable rubber film .

  In the fluid-filled vibration isolator constructed according to this aspect, when a small amplitude vibration having a frequency higher than the resonance frequency of the fluid flowing through the first orifice passage is input, Pressure fluctuations induced in the pressure receiving chamber as the flow resistance significantly increases are exerted on the movable rubber film through the pressure receiving chamber side window. The pressure fluctuation in the pressure receiving chamber is reduced or eliminated by being released to the equilibrium chamber through the window on the equilibrium chamber side based on the minute displacement or deformation of the movable rubber film, thereby exhibiting a good vibration isolation effect. Can be done.

  Particularly in this embodiment, the second orifice passage is formed by the pressure receiving chamber side window portion and the equilibrium chamber side window portion. Therefore, when a vibration having a frequency close to or close to the resonance frequency of the fluid flowing through the second orifice passage is input, the movable rubber film is based on the resonance action of the fluid flowing through the second orifice passage. The low dynamic spring effect can be produced more effectively, and the hydraulic pressure absorbing action based on the minute displacement of the movable rubber film can be produced more effectively.

  Further, particularly in this embodiment, the natural frequency of elastic deformation of the movable rubber film is set on the high frequency side compared to the resonance frequency of the fluid that flows through the second orifice passage. Therefore, in the state where the natural frequency of elastic deformation of the movable rubber film or a high frequency vibration close thereto is input, the flow resistance of the fluid flowing through the second orifice passage is remarkably increased, and the second orifice The fluid pressure exerted on the movable rubber membrane through the passage is limited. Therefore, in a state where the natural frequency of elastic deformation of the movable rubber film is input, the displacement due to the resonance of the movable rubber film can be suppressed by suppressing the pressure fluctuation exerted on the movable rubber film. As a result, the hitting of the partition member due to the resonance displacement of the movable rubber film can be suppressed, and the generation of abnormal noise can be suppressed. In this aspect, since it is possible to suppress the resonance displacement without directly restraining the movable rubber film, the vibration is higher in frequency than the resonance frequency of the fluid flowing through the first orifice passage. On the other hand, it is possible to suppress the generation of abnormal noise and the like without impairing the low dynamic spring effect due to the minute displacement of the movable rubber film.

  In addition, the natural frequency of elastic deformation of the movable rubber film in this aspect does not mean the natural frequency of the movable rubber film alone, but is assembled in the vibration isolator to hold the outer peripheral edge. It means the natural frequency of elastic deformation of the movable rubber film that is expressed in a specific state disposed in the fluid. That is, the natural frequency of elastic deformation of the movable rubber film and the resonance frequency of the fluid that flows through the second orifice passage in this embodiment are specified in relation to each other in the assembled state to the vibration isolator. is there.

  In the fluid-filled vibration isolator having the structure according to this aspect, the dynamic spring constant of the movable rubber film is set high by holding the outer peripheral edge portion and the central portion of the movable rubber film narrowly, and the movable rubber film The natural frequency of elastic deformation can be set in a high frequency region. At the same time, by setting the opening size of the pressure receiving chamber side window portion to be small, it is possible to effectively cause the fluid flow action by the second orifice passage formed including the pressure receiving chamber side window portion. As a result, when vibration corresponding to the natural frequency of elastic deformation of the movable rubber film is input, the vibration is higher than the tuning frequency of the second orifice passage. Becomes a substantially closed state, resulting in a markedly high dynamic spring. Accordingly, the resonance displacement of the movable rubber film can be restrained and restrained by the fluid, and the hitting of the partition member due to the resonance displacement can be advantageously restrained.

  According to a third aspect of the present invention, in the fluid-filled vibration isolator according to the first or second aspect, the resonance frequency of the fluid allowed to flow through the second orifice passage is within a range of 50 Hz to 200 Hz. And the natural frequency of elastic deformation of the movable rubber film is set in the range of 200 Hz to 500 Hz.

  In the fluid-filled vibration isolator having the structure according to this aspect, the hydraulic pressure absorbing action of the movable rubber film based on the fluid action of the fluid flowing through the second orifice passage against high-frequency small-amplitude vibration such as traveling noise. When high-frequency acceleration noise is input compared to running noise, the use of high dynamic springs based on substantial blockage of the second orifice passage is used. By suppressing the resonance displacement of the movable rubber film, it is possible to suppress the hit of the movable rubber film against the partition member. Therefore, it is possible to obtain an excellent anti-vibration effect against high-frequency vibration due to the hydraulic pressure absorption action and to suppress the generation of abnormal noise.

  Hereinafter, in order to clarify the present invention more specifically, embodiments of the present invention will be described in detail with reference to the drawings.

  First, FIG. 1 shows an automobile engine mount 10 as a fluid-filled vibration isolator as one embodiment of the present invention. In the engine mount 10, a main mounting rubber elastic body 16 includes a first mounting bracket 12 as a first mounting member and a second mounting bracket 14 as a second mounting member which are disposed at a predetermined distance from each other. The first mounting bracket 12 is attached to a power unit (not shown) while the second mounting bracket 14 is attached to a mounting hole 84 provided in the vehicle body via a bracket 82 described later. By being press-fitted and attached to the vehicle body side, the power unit is supported in a vibration-proof manner with respect to the vehicle body. Further, under such a mounted state, the engine mount 10 has a shared load of the power unit between the first mounting bracket 12 and the second mounting bracket 14 in the mount center axis direction which is the vertical direction in FIG. As a result, the main rubber elastic body 16 is elastically deformed in the direction in which the first mounting bracket 12 and the second mounting bracket 14 approach each other. Further, the main vibration to be vibration-proofed is input between the first mounting bracket 12 and the second mounting bracket 14 in a direction in which the mounting brackets 12 and 14 approach / separate each other. ing. In the following explanation, the vertical direction means the vertical direction in FIG. 1 in principle.

  More specifically, the first mounting member 12 has a substantially columnar shape with a protruding tip portion having a truncated frustoconical shape in the reverse direction, and a flange extending radially outward at the upper end portion in the axial direction. The part 18 is integrally formed. Further, a bolt hole 20 that opens upward is formed on the central axis of the first mounting bracket 12, and the first mounting bracket 12 is secured by a fixing bolt (not shown) that is screwed into the bolt hole 20. It is designed to be fixed on the power unit side. In addition, a circumferential positioning protrusion 21 protrudes upward and is integrally formed on the upper end surface of the first mounting member 12.

  On the other hand, the second mounting bracket 14 includes a cylindrical portion 22 having a large-diameter cylindrical shape, and a constricted portion that protrudes radially inward by bending or the like at the upper opening of the cylindrical portion 22. 24 is formed, and a flange-like portion 26 that extends outward in the radial direction is integrally formed at the opening periphery of the constricted portion 24.

  The first mounting bracket 12 is disposed on the substantially same central axis at a predetermined distance above the second mounting bracket 14 in the axial direction, and the first mounting bracket 12 and the second mounting bracket 12 are attached to each other. The metal fitting 14 is elastically connected by the main rubber elastic body 16. The main rubber elastic body 16 has a large-diameter substantially truncated cone shape, and a large-diameter recess 28 that opens downward in the axial direction is formed on the large-diameter side end face. Further, the first mounting bracket 12 is embedded in the small diameter side end portion of the main rubber elastic body 16 and vulcanized and bonded, and the large diameter side end outer peripheral surface is within the upper end portion of the second mounting bracket 14. The peripheral surface is vulcanized and bonded. Thus, the first mounting bracket 12 and the second mounting bracket 14 are connected by the main rubber elastic body 16, and one opening of the cylindrical portion 22 of the second mounting metal 14 is the main rubber elastic body. 16 is closed fluid-tightly. A seal rubber 30 integrally formed with the main rubber elastic body 16 is attached to the inner peripheral surface of the cylindrical portion 22 of the second mounting bracket 14 over substantially the entire surface. The main rubber elastic body 16 is formed to extend above the flange-shaped portion 26 of the second mounting bracket 14, and the main rubber elastic body 16 is attached to the upper surface of the flange-shaped portion 26. ing.

  Further, a diaphragm 32 as a flexible film is disposed in the lower opening of the second mounting bracket 14. The diaphragm 32 is a thin rubber film having a substantially dome shape that has sufficient slack and is easily deformed. A cylindrical contact portion 33 is integrally formed at the center portion of the diaphragm 32. Further, a metal ring 34 is vulcanized and bonded to the outer peripheral edge of the diaphragm 32. Then, after the metal ring 34 is inserted into the lower opening of the second mounting bracket 14, the second mounting bracket 14 is subjected to diameter reduction processing or caulking processing, whereby the metal ring 34 is The metal ring 34 is axially lowered by a locking claw 36 formed by being fitted and fixed to the mounting bracket 14 and bending the opening peripheral edge of the second mounting bracket 14 radially inward. The escape to the is prevented. As a result, the lower opening of the second mounting bracket 14 is fluid-tightly closed by the diaphragm 32, so that the main rubber elastic body 16 and the diaphragm 32 are opposed to each other inside the second mounting bracket 14. Between the surfaces, a fluid chamber 38 in which an incompressible fluid is sealed is formed. As the incompressible fluid sealed in the fluid chamber 38, water, alkylene glycol, polyalkylene glycol, silicone oil, or the like can be used. However, the vibration isolation effect based on the resonance action of the fluid described later is effective. Therefore, a low-viscosity fluid having a viscosity of 0.1 Pa · s or less is desirable.

  A partition member 40 having a substantially cylindrical shape as a whole is accommodated in the fluid chamber 38 formed in this manner, and the outer peripheral edge of the partition member 40 has a main rubber elastic body 16. Is held between the large-diameter side end face of the metal ring 34 and the upper end face in the axial direction of the metal ring 34, and the outer peripheral face thereof is held narrowly by the second mounting fitting 14 having a reduced diameter. The mounting bracket 14 is fixedly supported. The fluid chamber 38 is partitioned in the axial direction by the partition member 40. Therefore, a part of the wall portion is constituted by the main rubber elastic body 16 on the upper side of the partition member 40, and pressure fluctuation occurs when vibration is input. A pressure receiving chamber 42 is formed, and an equilibration chamber 44 is formed below the partition member 40. The equilibrium chamber 44 is formed with a part of the wall portion of the diaphragm 32 and the volume change is allowed.

  As shown in FIGS. 2 and 3, the partition member 40 is configured by superimposing a first partition fitting 46 and a second partition fitting 48 serving as divided partition plates on each other in the plate thickness direction. . In addition, as these 1st and 2nd partition metal fittings 46 and 48, although a press-molded product and a die-cast molded product can be employ | adopted, for example, even if formed with the hard synthetic resin material by which injection molding was carried out good.

  The first partition fitting 46 has a thick, substantially disk shape, and a recess 50 having a large-diameter circular shape that opens upward is formed in the center portion. In the central portion of the bottom of the recess 50, a plurality of (four in the present embodiment) upper through holes 52 as the pressure receiving chamber side windows are provided in the thickness direction. Each upper through-hole 52 has a substantially 扇 -shaped shape having a diameter of about 1/3 of the diameter of the bottom of the recess 50 and extending over about ¼ circumference. The four upper through holes 52 are arranged at substantially equal intervals in the circumferential direction of the bottom of the recess 50. In addition, a circumferential groove 54 is formed in the outer peripheral edge portion of the first partition metal 46 so as to surround the recess 50 and extend in a radially outward direction, extending a little less than one round.

  On the other hand, the second partition metal 48 has a thick, substantially disk shape having substantially the same outer diameter as that of the first partition metal 46, and has a large opening at the center thereof. A recess 56 having a circular shape with a diameter is formed with an inner diameter dimension slightly smaller than the bottom of the recess 50 formed in the first partition metal fitting 46. A plurality (four in the present embodiment) of lower through holes 58 serving as equilibrium chamber side windows are provided in the center portion of the bottom of the recess 56 in the thickness direction. Each lower through hole 58 has a shape similar to that of the upper through hole 52 formed in the first partition metal fitting 46, and has a diameter of about 1/3 of the diameter of the bottom of the recess 56 and is approximately 1 / 4 It is made into the substantially fan shape which spreads over 4 circumferences. The four lower through holes 58 are disposed at substantially equal intervals in the circumferential direction of the bottom of the recess 56. On the opposite side of the recess 56 in the second partition metal fitting 48, a circular lower recess 60 having a diameter substantially equal to that of the recess 56 and opening downward is formed, and the bottom wall of the recess 56 is formed. The thickness dimension is reduced. In addition, a circumferential groove 62 that extends a little less than one round so as to surround the recess 56 is formed on the outer peripheral edge of the second partition metal 48 so as to open upward.

  And the partition member 40 is comprised by the 1st partition metal fitting 46 and the 2nd partition metal fitting 48 being piled up and down on the central axis, and being assembled | attached fixedly. Here, the opening of the recess 56 of the second partition fitting 48 is covered with the bottom surface of the first partition fitting 46, so that an accommodation space 64 is formed in the central portion in the partition member 40. Yes.

  A rubber elastic film 66 as a movable rubber film is accommodated in the accommodation space 64. The rubber elastic film 66 has a generally disc shape as a whole, and is thicker than the main body portion 68 in the axial direction with respect to the outer peripheral edge portion of the disc-shaped main body portion 68 having a substantially constant thickness dimension. An outer periphery holding portion 70 is integrally formed as an annular protrusion that protrudes on both sides and continuously extends over the entire circumferential direction. Furthermore, a central holding portion 72 is integrally formed at the central portion of the rubber elastic film 66 as a central protrusion that is thicker than the main body portion 68 and protrudes on both sides in the axial direction. The main body portion 68 includes a plurality of annular rib protrusions 74 that protrude slightly in the vertical direction of the main body portion 68 and extend over the entire circumference on the concentric axis with the main body portion 68 (in this embodiment, 2 When the rubber elastic film 66 is excessively displaced, the first or second partition metal fittings 46 and 48 are abutted against each other in a shock-absorbing manner.

  With the rubber elastic film 66 having such a structure accommodated in the recess 56 of the second partition metal 48, the first partition metal 46 is overlaid from above, so that the inside of the partition member 40 is obtained. The accommodation space 64 is formed, and the rubber elastic film 66 is accommodated in the accommodation space 64. The central sandwiching portion 72 and the outer periphery sandwiching portion 70 of the rubber elastic film 66 are sandwiched from above and below in the axial direction by the bottom surface of the recess 56 and the bottom surface of the first partition member 46 in the second partition member 48. As a result, the center holding portion 72 is nipped and fixed, and the outer periphery holding portion 70 is fixed in a fluid-tight manner. Here, it is preferable that the diameter of the central holding portion 72 is 2 to 5 mm, and the tightening margin is 5 to 30%. In this embodiment, the diameter of the central holding portion 72 is 5 mm and the axial direction. The height dimension is 7 mm at non-narrow pressure to 6 mm at narrow pressure, and the tightening margin is (7-6) /7≈14.3%.

  Thus, the main body portion 68 of the rubber elastic film 66 accommodated and disposed in the accommodation space 64 is disposed in a stretched state in a direction perpendicular to the axis. The upper surface of the main body portion 68 is directly exposed to the upper pressure receiving chamber 42 through the upper through hole 52 of the first partition member 46 so that the pressure of the pressure receiving chamber 42 is exerted. On the other hand, the lower surface of the main body portion 68 is directly exposed to the lower equilibrium chamber 44 through the lower through-hole 58 of the second partition member 48 so that the pressure of the equilibrium chamber 44 is exerted. Here, the total opening area of the upper through holes 52 formed in the first partition metal fitting 46 is set within a range of 1/3 to 1/2 of the area of the main body portion 68 of the rubber elastic film 66. . In particular, in the present embodiment, the lower through hole 58 of the second partition fitting 48 is also substantially the same shape as the upper through hole 52 of the first partition fitting 46. Is also set within a range of 1/3 to 1/2 of the area of the main body portion 68 of the rubber elastic film 66.

  The rubber elastic film 66 has a central sandwiching portion 72 and an outer peripheral sandwiching portion 70 sandwiched between the first and second partition fittings 46 and 48, while the other main body portion 68 is composed of the first and second partitioning portions 46 and 48. The second partition members 46 and 48 are spaced apart from each other, so that substantially the entire main body portion 68 is disposed in an unconstrained state with respect to the first and second partition members 46 and 48 in the vertical direction. The body portion 68 is allowed to be freely deformed.

  As apparent from this, in the present embodiment, the upper through hole 52 and the lower through hole 58 constitute a through hole, and a rubber elastic film 66 is disposed so as to close the through hole. A pressure absorbing mechanism is configured in which the rubber elastic film 66 is elastically deformed based on a pressure difference between the pressure receiving chamber 42 and the equilibrium chamber 44 exerted on both surfaces of the rubber elastic film 66. Here, the natural frequency of the elastic deformation of the rubber elastic film 66 is set in the accommodating space 64 in which the fluid is sealed, and the central holding portion 72 and the outer peripheral holding portion 70 are held and fixed. In the assembled state, it is set to a predetermined frequency within a range of 200 Hz to 500 Hz.

  At the same time, a second orifice passage 75 is formed by the upper through hole 52 and the lower through hole 58. Based on the resonance action of the fluid that flows through the second orifice passage 75, a traveling boom noise or the like is generated. The channel cross-sectional areas and lengths of the upper and lower through holes 52 and 58 are set so that an effective vibration-proofing effect against high-frequency vibrations is exhibited. Particularly in this embodiment, the tuning frequency of the second orifice passage 75 formed by the upper and lower through holes 52 and 58 is set to a value lower than the natural frequency of elastic deformation of the rubber elastic film 66. For example, it is set to a predetermined frequency within a range of 50 Hz to 200 Hz.

  Further, the peripheral groove 62 of the second partition fitting 48 is covered with the first partition fitting 46 at the outer peripheral edge of the partition member 40, while the circumferential groove 54 of the first partition fitting 46 is sealed with the seal rubber 30. And the connection hole 73 formed at the bottom of the circumferential groove 54 of the first partition fitting 46 and penetrating in the thickness direction is connected to the circumferential groove 62 of the second partition fitting 48. A first orifice passage 76 extending in the circumferential direction with a length of a little less than two rounds is formed in the outer circumferential portion of the partition member 40, and the first orifice passage 76 has first and second end portions in the circumferential direction. It communicates with each one of the pressure receiving chamber 42 and the equilibrium chamber 44 through communication holes 78 and 80 formed in the second partition metal fittings 46 and 48. Then, based on the pressure difference generated between the pressure receiving chamber 42 and the equilibrium chamber 44 at the time of vibration input, a predetermined vibration isolation effect is exhibited by the flow action of the fluid flowing through the first orifice passage 76. It has become. In the present embodiment, the first orifice is effective so as to exhibit an effective anti-vibration effect against low-frequency vibration such as a shake based on the resonance action of the fluid flowing through the first orifice passage 76. The flow path cross-sectional area and length of the passage 76 are set.

  For example, as shown in FIG. 4, the engine mount 10 having such a structure is press-fitted and fixed in a mounting hole 84 of a bracket 82 welded to a bracket fixed to a body of an automobile. The bracket 82 has a large-diameter substantially cylindrical shape, and a flange-like portion 86 that extends outward in the radial direction is integrally formed in the opening on the upper side in the axial direction, while the bottom wall at the lower end in the axial direction is formed. A communication hole 88 is provided through the part.

  Then, the engine mount 10 is press-fitted and fixed to the bracket 82 from above in the axial direction. Here, the flange-like portion 26 of the second mounting bracket 14 in the engine mount 10 is overlapped with the flange-like portion 86 of the bracket 82.

  In this way, the engine mount 10 is press-fitted and fixed to the mounting hole 84 of the bracket 82 welded to the bracket fixed to the vehicle body, so that the second mounting bracket 14 is moved to the vehicle body side. It is attached. On the other hand, the first mounting bracket 12 is attached to a power unit (not shown) by a bolt or the like that is screwed into the bolt hole 20 so that the power unit is supported in a vibration-proof manner with respect to the vehicle body. .

  In the engine mount 10 having the above-described structure, when vibrations in a substantially vertical direction are input between the first mounting bracket 12 and the second mounting bracket 14 while being mounted on an automobile, for example, In the case of vibration in a low frequency range such as an engine shake, the relative pressure difference is generated between the pressure receiving chamber 42 and the equilibrium chamber 44. An effective anti-vibration effect is exhibited based on the resonance action of the fluid flowing through one orifice passage 76.

  On the other hand, when the input vibration is a vibration in a frequency range higher than the tuning frequency of the first orifice passage 76 such as a traveling noise, the flow resistance of the first orifice passage 76 is remarkably increased. Accordingly, the large pressure fluctuation caused in the pressure receiving chamber 42 is reduced or eliminated by the minute elastic deformation of the rubber elastic film 66 and the resonance action of the fluid flowing through the second orifice passage 75. As a result, an extremely high dynamic spring due to the substantial obstruction of the first orifice passage 76 is avoided, and an effective anti-vibration effect is exhibited.

  Further, the input vibration is a vibration in a higher frequency range than the tuning frequency of the second orifice passage 75 such as an engine acceleration noise, for example, in a frequency range close to the natural frequency of the rubber elastic film 66. In the case of vibration, a resonance frequency for causing the rubber elastic film 66 to resonate is given. However, in the present embodiment, the tuning frequency of the second orifice passage 75 is set on the low frequency side as compared with the natural frequency of elastic deformation of the rubber elastic film 66. Therefore, when vibration in a frequency range that causes the rubber elastic film 66 to resonate is input, the flow resistance of the second orifice passage 75 is remarkably increased to make it a highly dynamic spring, whereby the fluid in the accommodation space 64 is obtained. Thus, the elastic rubber film 66 can be restrained, and the resonance displacement of the elastic rubber film 66 can be suppressed. Therefore, it is possible to suppress the rubber elastic film 66 from hitting the first and second partition members 46 and 48, and to suppress the generation of abnormal noise resulting from such hitting.

  As mentioned above, although one Embodiment of this invention was explained in full detail, this is an illustration to the last, Comprising: This invention is not limited at all by the specific description in this Embodiment.

  For example, the central holding portion 72 formed in the rubber elastic film 66 is not always necessary, and the elastic deformation of the rubber elastic film 66 is adjusted by adjusting the thickness dimension of the main body portion 68 of the rubber elastic film 66. The natural frequency may be adjusted.

  In the above embodiment, the outer peripheral edge of the movable rubber film is fixedly supported by the partition member by holding the outer peripheral edge of the movable rubber film with a narrow pressure. The movable rubber film is fixed to the partition member by vulcanizing and bonding the outer peripheral edge of the movable rubber film to the partition member or by bonding the outer peripheral edge of the vulcanized movable rubber film to the partition member. It is also possible to support it.

  Furthermore, in the above-described embodiment, the shape of the equilibrium chamber side window that applies the pressure of the equilibrium chamber to the movable rubber film is the same shape as the pressure receiving chamber side window that applies the pressure of the pressure receiving chamber to the movable rubber film. However, the equilibrium chamber side window may be formed sufficiently large. In this way, the second orifice passage formed by the pressure receiving chamber side window and the equilibrium chamber side window can be formed substantially only by the pressure receiving chamber side window. The tuning frequency of the second orifice passage can be set by adjusting only the cross-sectional area and length of the second orifice passage.

  In addition, although not enumerated one by one, the present invention can be carried out in a mode to which various changes, modifications, improvements and the like are added based on the knowledge of those skilled in the art. It goes without saying that all are included in the scope of the present invention without departing from the spirit of the present invention.

  Tests conducted to confirm the technical effects of the fluid filled type vibration damping device according to the present invention will be described below as examples.

  First, as an example, the engine mount 10 in the above-described embodiment is prepared, and as a comparative example according to the conventional structure, the opening area of the upper through hole 52 and the lower through hole 58 in the engine mount 10 is the main body portion 68 of the rubber elastic film 66. We prepared an engine mount that was approximately the same size. Here, the opening size of the upper through hole 52 and the lower through hole 58 of the engine mount 10 as an embodiment according to the present invention is substantially the same as the opening size of the upper through hole and the lower through hole of the engine mount as a comparative example according to the conventional structure. It is set to 1/2.

  A load corresponding to the engine weight is applied to these engine mounts at room temperature, and vibrations of 100 Hz to 300 Hz with a constant amplitude = 0.05 mm are applied to the first mounting bracket 12 side under such conditions. Changes in the dynamic spring constants of these engine mounts when input was made while gradually changing were measured. FIG. 5 shows a measurement result of the engine mount 10 having a structure according to the present invention as an example, and also shows an engine mount having a structure according to a conventional structure as a comparative example.

  In FIG. 5, the resonance of the movable rubber film is detected as a change that decreases after the dynamic spring constant increases, while the orifice resonance is detected as a change that increases after the dynamic spring constant decreases. As is clear from FIG. 5, in the comparative example according to the conventional structure, when vibration of approximately 170 Hz is input, resonance 92 of the movable rubber film is generated and when vibration of approximately 250 Hz is input. An orifice resonance 94 is produced. On the other hand, in the embodiment according to the present invention, when vibration of approximately 140 Hz is input, the orifice resonance 96 is generated, and the frequency of approximately 230 Hz in a high frequency range is higher than the frequency at which the orifice resonance is generated. When vibration is input, resonance 98 of the movable rubber film is generated.

  That is, in the conventional structure, the resonance state of the movable rubber film is generated prior to the orifice resonance, and therefore, it is easy for the partition member to hit by the resonance of the movable rubber film. On the other hand, according to the present invention, since the resonance state of the movable rubber film is generated by vibration input having a frequency higher than the tuning frequency of the orifice, vibration having a frequency that resonates the movable rubber film is input. In this case, the flow resistance of the fluid flowing through the orifice can be remarkably increased to make a highly dynamic spring, and displacement due to resonance of the movable rubber film can be suppressed by the fluid. Therefore, it is possible to suppress the hit of the movable rubber film, and to suppress the occurrence of abnormal noise caused by such hit. Further, in the embodiment according to the present invention, the maximum value of the dynamic spring constant is lower than that of the comparative example, and in the high frequency range, the dynamic spring constant is comparable to that of the comparative example. Has been. In the embodiment, the frequency region in which the dynamic spring constant is maximum is positioned on the lower frequency side as compared with the comparative example, and the change of the dynamic spring constant is also gentle compared with the comparative example. . As described above, in the fluid filled type vibration damping device having the structure according to the present invention, it is possible to obtain a superior vibration damping effect in preventing abnormal noise while suppressing deterioration of the dynamic spring constant in a higher frequency range. it is obvious.

1 is a longitudinal sectional view showing a fluid-filled vibration isolator as one embodiment of the present invention. II-II sectional drawing in FIG. III-III sectional drawing in FIG. The longitudinal cross-sectional view which shows the attachment state to the vehicle of the fluid enclosure type vibration isolator shown in FIG. The graph which shows the result of having measured the spring characteristic of the fluid enclosure type damping device shown in FIG. 1 with the measurement result of a comparative example.

Explanation of symbols

10: Engine mount, 12: First mounting bracket, 14: Second mounting bracket, 16: Rubber elastic body, 32: Diaphragm, 40: Partition member, 42: Pressure receiving chamber, 44: Equilibrium chamber, 52: Upper part Through-hole, 58: Lower through-hole, 66: Rubber elastic membrane, 70: Peripheral pinching portion, 75: Second orifice passage, 76: First orifice passage

Claims (3)

A pressure receiving chamber in which a first mounting member and a second mounting member are connected by a main rubber elastic body, a part of the wall portion is configured by the main rubber elastic body, and pressure fluctuations are generated at the time of vibration input; and a wall portion Are formed on both sides sandwiching the partition member supported by the second mounting member, and a part of the pressure receiving chamber and the equilibrium chamber are formed. A first orifice passage that encloses the incompressible fluid and connects the pressure receiving chamber and the equilibrium chamber to each other is provided on the outer periphery of the partition member, and a movable rubber film is disposed in a central portion of the partition member. And a pressure receiving chamber side window portion that applies pressure of the pressure receiving chamber to one surface of the movable rubber film, and an equilibrium chamber side window portion that applies pressure of the equilibrium chamber to the other surface of the movable rubber film. In the fluid-filled vibration isolator having a pressure absorbing mechanism provided in
The partition member holds the outer peripheral edge portion and the central portion of the movable rubber film with pressure , while the pressure receiving chamber side window portion and the equilibrium chamber side window portion form a second orifice passage, and the movable rubber film The natural frequency of the elastic deformation of the movable rubber film is set on the high frequency side as compared with the resonance frequency of the fluid that flows through the second orifice passage based on the elastic deformation of the movable member, and the pressure receiving force in the partition member A fluid-filled vibration isolator characterized in that the opening area of the chamber-side window is set within a range of 1/3 to 1/2 of the area of the movable part in the movable rubber film .
The fluid-filled vibration isolator according to claim 1, wherein a central portion of the movable rubber film held and clamped by the partition member has a diameter of 2 to 5 mm and a tightening allowance of 5 to 30% .
  2. The resonance frequency of the fluid that is caused to flow through the second orifice passage is set within a range of 50 Hz to 200 Hz, and the natural frequency of elastic deformation of the movable rubber film is set within a range of 200 Hz to 500 Hz. Or the fluid-filled vibration isolator according to 2.

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