JP5847029B2 - Fluid filled vibration isolator - Google Patents

Description

  The present invention relates to a fluid-filled vibration isolator that is applied to an engine mount or the like of an automobile.

  2. Description of the Related Art Conventionally, there has been known a fluid-filled vibration isolator that is interposed between one member and the other member constituting a vibration transmission system, and that these members mutually provide anti-vibration connection or anti-vibration support. In the fluid-filled vibration isolator, a first attachment member attached to one member constituting a vibration transmission system and a second attachment member attached to the other member are elastically connected by a main rubber elastic body. It has a structure. Furthermore, a pressure receiving chamber and an equilibrium chamber filled with an incompressible fluid are formed on both sides of the partition member supported by the second mounting member, and the pressure receiving chamber and the equilibrium chamber communicate with each other by an orifice passage. Has been. Furthermore, in order to obtain an anti-vibration effect against vibration at a frequency higher than the tuning frequency of the orifice passage, a plate-shaped movable member is disposed in the accommodation space of the partition member, and the pressure receiving chamber is balanced on both surfaces of the movable member. A structure in which the hydraulic pressure of one of the chambers is exerted is also adopted. For example, Japanese Patent Application Laid-Open No. 2010-7836 (Patent Document 1).

  By the way, in the fluid filled type vibration isolator, there is a possibility that the generation of abnormal noise due to cavitation becomes a problem when a shocking heavy load is input. That is, when the pressure in the pressure receiving chamber is significantly reduced due to the input of a large load, bubbles due to cavitation are generated in the pressure receiving chamber, and abnormal noise based on the energy of the shock wave when the bubbles disappear may be generated.

  Therefore, in Patent Document 1 or the like, a leak hole is formed to communicate the accommodating space for accommodating the movable member and the pressure receiving chamber, and further, the accommodating space is blocked from the equilibrium chamber by the movable member when the pressure receiving chamber is pressurized. In addition, the accommodation space is communicated with the equilibrium chamber when the pressure receiving chamber is depressurized. As a result, when a negative pressure is exerted on the pressure receiving chamber, the pressure receiving chamber and the equilibrium chamber communicate with each other through the accommodation space and the leak hole, so that the fluid flows from the equilibrium chamber to the pressure receiving chamber, thereby reducing the negative pressure in the pressure receiving chamber. Thus, the generation of abnormal noise caused by cavitation is prevented. In the structure of Patent Document 1, the movable member has a movable film structure in which the movable member is sufficiently positioned with respect to the partition member, and a hydraulic pressure absorbing action is exhibited by deformation of the movable film, and even when the movable film is in a deformed state. It cannot come into contact with the inner wall surface of the housing space provided with the leak hole. Therefore, communication between the pressure receiving chamber and the equilibrium chamber through the accommodation space and switching between the shutoff are stably realized by the deformation of the movable film, and generation of cavitation noise is effectively prevented. .

  However, in order to obtain a vibration isolation effect or the like based on the hydraulic pressure transmission effect exerted by deformation or displacement of the movable member, a case where a structure that allows the displacement of the movable member relative to the partition member is more easily adopted, etc. Then, it is difficult to uniformly determine the deformation or displacement of the movable member. When the movable member can be deformed or displaced relatively freely in the accommodation space as described above, the opening of the leak hole is covered with the movable member depending on the deformation or displacement of the movable member. There was a risk of being blocked.

JP 2010-7836 A

  The present invention has been made in the background of the above-described circumstances, and the problem to be solved is a simple method using the movable member while effectively obtaining the vibration-proofing effect exhibited by the deformation or displacement of the movable member. An object of the present invention is to provide a fluid-filled vibration isolator having a novel structure capable of stably reducing cavitation noise due to the structure.

  That is, according to the first aspect of the present invention, the first attachment member and the second attachment member are elastically connected by the main rubber elastic body, and the partition member supported by the second attachment member is sandwiched between the first attachment member and the second attachment member. A pressure receiving chamber in which a part of the wall is made of the main rubber elastic body is formed on the side of the wall, and an equilibrium chamber in which a part of the wall is made of a flexible film is formed on the other side. In addition, an orifice passage is formed to allow the pressure receiving chamber and the equilibrium chamber to communicate with each other. A plate-like movable member is disposed in the accommodation space formed in the partition member, and the movable chamber is movable. In the fluid filled type vibration damping device in which one of the fluid pressure in the pressure receiving chamber and the fluid pressure in the equilibrium chamber is exerted on both surfaces of the member, a cylindrical buffer is disposed in the accommodation space. The movable member is disposed in the central hole of the cylindrical buffer, and the peripheral wall of the cylindrical buffer is formed in the housing space. A leak space that is overlapped with the contact surface of the movable member on the inner surface and that opens to the inner surface of the peripheral wall of the storage space that is overlapped with the opening end surface of the cylindrical shock absorber and extends outward from the storage space Is formed, and a leak hole is formed to communicate the leak void with the pressure receiving chamber, and a short-circuit passage that communicates the pressure receiving chamber and the equilibrium chamber when the pressure receiving chamber is depressurized with the leak void. The leak hole is formed to include the opening, and the opening of the leak space to the accommodation space is either in the thickness direction of the movable member or in the axial direction of the cylindrical shock absorber. It is characterized by being made smaller than the movable member in the length direction orthogonal to the above.

  According to the fluid-filled vibration isolator configured as described above according to the first aspect, when a large negative pressure is applied to the pressure receiving chamber, the fluid flows into the pressure receiving chamber from the equilibrium chamber through the short-circuit path. The pressure drop in the pressure receiving chamber is alleviated. As a result, the generation of bubbles due to cavitation is avoided, and cavitation noise due to shock waves or the like when the bubbles disappear is prevented.

  Moreover, the opening of the cylindrical shock absorber is arranged so as to face the opening of the leak cavity, and the short hole is formed by the central hole of the cylindrical shock absorber communicating with the leak cavity, thereby forming a short circuit. The passage is formed with a sufficient passage cross-sectional area, and the reduction of cavitation noise is effectively realized.

  In this case, since the movable member is disposed in the central hole of the cylindrical shock absorber, the movable member enters the leak void formed in the axially outward direction of the cylindrical shock absorber. This is prevented by making the portion smaller than the movable member. Therefore, by connecting the central hole of the cylindrical shock absorber to the leak space, the short-circuit path is formed with a sufficient cross-sectional area, and unintentional blocking of the short-circuit path due to the movable member entering the leak space is prevented. Thus, cavitation noise can be stably and effectively prevented.

  The cylindrical shock absorber is larger than the movable member in the length direction, as is apparent from the fact that the movable member is disposed in the central hole. Therefore, the opening to the accommodation space of the leak space is made smaller than the movable member in the length direction, so that the cylindrical shock absorber is disposed non-adhering in the accommodation space and is relative to the partition member. When the displacement is allowed, the cylindrical shock absorber is prevented from entering the leak space, and the short-circuit path is kept in communication.

  Further, by arranging the movable member in the central hole of the cylindrical shock absorber, it is possible to effectively reduce the hitting sound generated when the movable member hits the wall inner surface of the housing space with a small number of parts. In combination with the above-described effect of preventing abnormal cavitation noise, excellent quietness is realized.

  According to a second aspect of the present invention, in the fluid-filled vibration isolator described in the first aspect, an inner dimension in the length direction of the leak space is an inner dimension in the length direction of the accommodation space. It is made smaller than the size.

  According to the second aspect, by making the leak void smaller in the length direction than the accommodation void, it is possible to make it difficult for the movable member disposed in the accommodation void to enter the leak void.

  According to a third aspect of the present invention, in the fluid-filled vibration isolator described in the second aspect, the leak void is formed in the middle in the length direction of the accommodation void.

  According to the third aspect, since a step is formed between the accommodation space and the leak space on both sides in the length direction, the movable member enters the leak space more due to contact with the step. Effectively prevented.

  According to a fourth aspect of the present invention, in the fluid-filled vibration isolator described in any one of the first to third aspects, between the leak void and the accommodation void, A restricting projection is formed to separate the accommodating cavity, and the opening to the accommodating cavity of the leak cavity is divided on both sides in the length direction across the restricting projecting part, and the leaked parts are divided. The openings of the voids to the accommodation voids are all made smaller than the movable member in the length direction.

  According to the fourth aspect, since the opening to the accommodation space of the leak space is divided by the restriction protrusion, even if a relatively large leak space is formed, the length direction of each opening Can be made smaller than the movable member. As a result, the movable member is prevented from entering the leak space by abutting against the restricting protrusion, and the short-circuit path is maintained in a communicating state.

  According to a fifth aspect of the present invention, in the fluid-filled vibration damping device according to any one of the first to fourth aspects, the pressure receiving chamber of the orifice passage is more leaky than the accommodating space. It is formed at a position close to the communication port on the side, and the opening of the leak hole to the pressure receiving chamber is disposed near the communication port on the pressure receiving chamber side of the orifice passage.

  According to the fifth aspect, when the internal pressure of the pressure receiving chamber decreases, the fluid that flows into the pressure receiving chamber from the equilibrium chamber through the short circuit passage is supplied to the vicinity of the communication port on the pressure receiving chamber side of the orifice passage where bubbles due to cavitation are likely to occur. . As a result, the negative pressure in the pressure receiving chamber in the vicinity of the communication port of the orifice passage is quickly reduced or eliminated, and the generation of bubbles due to cavitation is reduced, so that noise caused by cavitation is prevented.

  According to the present invention, the leak space that is communicated with the pressure receiving chamber and the accommodation space to form the short-circuit path is made smaller than the movable member in the length direction at the opening to the accommodation space. This prevents the movable member from entering the leak space through the opening of the cylindrical shock absorber, even if the leak space is formed on the opening side of the cylindrical shock absorber with respect to the housing space. This can prevent the leak hole from being blocked by the movable member. Therefore, when the pressure in the pressure receiving chamber is reduced, the short-circuit path is stably maintained in a communication state, and the generation of abnormal noise due to cavitation is prevented.

It is a longitudinal cross-sectional view which shows the engine mount as the 1st Embodiment of this invention, Comprising: The figure corresponded in the II cross section of FIG. It is another longitudinal cross-sectional view of the engine mount shown by FIG. 1, Comprising: The figure corresponded in the II-II cross section of FIG. The top view of the partition member which comprises the engine mount shown by FIG. The top view which shows the state which removed the upper partition member from the partition member shown by FIG. The top view which shows the shock absorbing rubber attached to the partition member shown by FIG. VI-VI sectional drawing of FIG. The longitudinal cross-sectional view of the principal part which shows the state in which the negative pressure was applied to the pressure receiving chamber in the engine mount shown by FIG. The top view which shows the state which removed the upper partition member from the partition member which comprises the engine mount as the 2nd Embodiment of this invention. The top view which shows the state which removed the upper partition member from the partition member which comprises the engine mount as the 3rd Embodiment of this invention. The top view which shows the state which removed the upper partition member from the partition member which comprises the engine mount as another one Embodiment of this invention. The top view which shows the partition member which comprises the engine mount as another one Embodiment of this invention.

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

  FIG. 1 and FIG. 2 show an engine mount 10 for an automobile as a first embodiment of a fluid filled type vibration damping device having a structure according to the present invention. The engine mount 10 has a structure in which a first attachment member 12 and a second attachment member 14 are elastically connected by a main rubber elastic body 16, and the first attachment member 12 is attached to a power unit (not shown). By attaching the second attachment member 14 to a vehicle body (not shown), the power unit is supported by the vehicle body in a vibration-proof manner. In the following description, the vertical direction means the vertical direction in FIG. 1 that is the axial direction of the engine mount 10 in principle.

  More specifically, the first mounting member 12 is a high-rigidity member formed of iron, aluminum alloy or the like, and has a generally circular block shape with a small diameter as a whole, and the upper portion has a substantially cylindrical shape. And has a substantially truncated cone shape in the opposite direction in which the lower portion gradually decreases in diameter toward the lower side. Further, the first mounting member 12 is formed with a bolt hole 18 extending vertically on the central axis and opening on the upper surface, and a thread is formed on the inner peripheral surface.

  The second mounting member 14 is a highly rigid member formed of the same material as the first mounting member 12 and has a thin cylindrical shape with a large diameter. In addition, a constricted portion 20 having a groove shape that opens to the outer peripheral side is provided at the upper end portion of the second mounting member 14, and the flange portion 22 protrudes from the upper end of the constricted portion 20 toward the outer peripheral side. Yes.

  Then, the first mounting member 12 and the second mounting member 14 are arranged such that the first mounting member 12 is spaced above the second mounting member 14 on the same central axis, and the first mounting member 12 12 and the second mounting member 14 are elastically connected by a main rubber elastic body 16. The main rubber elastic body 16 has a thick-walled large-diameter substantially truncated cone shape, and the end portion on the small-diameter side is vulcanized and bonded to the first mounting member 12, and the end portion on the large-diameter side is also vulcanized. The constricted portion 20 of the second attachment member 14 is overlapped and vulcanized and bonded to the outer peripheral surface. In the present embodiment, the main rubber elastic body 16 is formed as an integrally vulcanized molded product including the first mounting member 12 and the second mounting member 14.

  Furthermore, a large-diameter recess 24 is formed in the main rubber elastic body 16. The large-diameter recess 24 is a recess having a substantially mortar shape in the opposite direction that opens to the large-diameter side end face of the main rubber elastic body 16, and is formed in the central portion in the radial direction of the main rubber elastic body 16.

  Furthermore, a seal rubber layer 26 extends from the outer peripheral side of the large-diameter recess 24 in the main rubber elastic body 16. The seal rubber layer 26 is a rubber elastic body having a thin and large-diameter substantially cylindrical shape, is integrally formed with the main rubber elastic body 16, and is fixed to the inner peripheral surface of the second mounting member 14.

  A flexible film 28 is attached to the integrally vulcanized molded product of the main rubber elastic body 16. The flexible film 28 is a rubber film having a thin disk shape or a circular dome shape, and has sufficient slackness in the axial direction. Further, an annular fixing portion 30 is integrally formed at the outer peripheral end portion of the flexible film 28, and the outer peripheral surface of the fixing portion 30 is vulcanized and bonded to the inner peripheral surface of the annular fixing member 32.

  Then, the fixing member 32 is inserted into the lower opening of the second mounting member 14, and the second mounting member 14 is subjected to diameter reduction processing such as an eight-way drawing, whereby the fixing member 32 is Fit on the mounting member 14, the flexible membrane 28 is disposed to close the lower opening of the second mounting member 14. A seal rubber layer 26 is interposed between the second mounting member 14 and the fixing member 32, and the second mounting member 14 and the fixing member 32 are fixed in a fluid tight manner.

  By attaching the flexible membrane 28 to the integrally vulcanized molded product of the main rubber elastic body 16 in this way, the space between the axially opposed surfaces of the main rubber elastic body 16 and the flexible membrane 28 is limited to the external space. Thus, a fluid chamber 34 is formed which is sealed and sealed with an incompressible fluid. The incompressible fluid sealed in the fluid chamber 34 is not particularly limited, and for example, water, alkylene glycol, polyalkylene glycol, silicone oil, or a mixture thereof can be used. Further, in order to efficiently obtain a vibration isolation effect based on the fluid flow action described later, it is desirable to employ a low viscosity fluid of 0.1 Pa · s or less.

  A partition member 36 is accommodated in the fluid chamber 34. The partition member 36 has a thick, substantially disk shape as a whole, and includes an upper partition member 38 and a lower partition member 40.

  As shown in FIGS. 1 to 3, the upper partition member 38 has a substantially disc shape, and a central recess 42 that opens upward is formed in the central portion in the radial direction, and will be described later. The volume of the chamber 72 is ensured efficiently. Furthermore, an upper groove 44 is formed at the outer peripheral end of the upper partition member 38 while being open to the outer peripheral surface and extending in a circumferential direction with a predetermined length, and one end of the upper groove 44 is an upper communication port 46. And communicated with the central recess 42, and the other end opens to the lower surface.

  Further, a first communication hole 48 penetrating vertically is formed in a central portion of the bottom wall of the central recess 42. The first communication hole 48 has a substantially rectangular shape when viewed in the axial direction, and a pair of first communication holes 48, 48 are provided at a predetermined distance in the short side direction. Further, a leak hole 50 is formed in the bottom wall portion of the central recess 42. The leak hole 50 is a circular hole having an opening area smaller than that of the first communication hole 48, and vertically penetrates the bottom wall portion of the central recess 42 at a position away from the first communication hole 48. Yes. Note that the leak hole 50 of the present embodiment is formed at a position closer to the upper communication port 46 of the upper groove 44 than the first communication hole 48.

  As shown in FIGS. 1 and 4, the lower partition member 40 has a substantially disk shape with a thick central portion, and a thin flange-like portion 52 projects from the lower end to the outer peripheral side thereof. ing. The flange-like portion 52 extends with a predetermined length less than one circumference in the circumferential direction, and one end portion is an inclined portion that gradually becomes thicker toward the outer side in the circumferential direction, and the other end portion. Is open downward in the axial direction. Further, between the both end portions of the flange-shaped portion 52, the same thick partition wall portion 56 as the central portion protrudes.

In addition, an accommodation recess 58 that opens upward is formed in the radial center portion of the lower partition member 40. The housing recess 58 has a substantially rectangular shape when viewed in the axial direction, and extends in the vertical direction with a substantially constant cross-sectional shape. In the following description, in principle, the long side direction (the vertical direction in FIG. 3) of the housing recess 58 will be described as the length direction. Further, the inner dimension of the housing recess 58 in the length direction is L ₁ .

  Further, a second communication hole 60 is formed through the bottom wall portion of the housing recess 58. The second communication hole 60 has a rectangular section substantially the same as that of the first communication hole 48 and extends up and down. Like the first communication hole 48, the second communication hole 60 is separated by a predetermined distance in the short side direction. Communication holes 60, 60 are provided. The second communication hole 60 is provided so that the short side direction thereof substantially coincides with the long side direction of the housing recess 58. In the combined state of the upper and lower partition members 38, 40 described later, The long side direction of the communication hole 48 substantially coincides with the long side direction of the second communication hole 60.

The lower partition member 40 is provided with a leak recess 62. The leak recess 62 is a recess that extends outward in the short side direction from the housing recess 58, and opens on the upper surface of the lower partition member 40. Further, the leakage recesses 62, together are formed in the central portion of the length direction of the housing recess 58, its length inside dimension: from L _1: the length direction inside dimension of L ₂ is housing recess 58 It is also small. In the present embodiment, the inner dimension of the leak recess 62 in the depth direction is substantially the same as the inner dimension of the housing recess 58 in the depth direction.

Further, a limiting protrusion 64 is provided between the leak recess 62 and the accommodation recess 58. The restricting projection 64 is formed in a connection opening to the accommodation recess 58 in the leak recess 62, and projects linearly from the bottom surface of the leak recess 62 upward with a substantially constant rectangular cross section. Further, the length dimension L _{3 of} the restriction protrusion 64 is smaller than the inner dimension L _{2 of} the leak recess 62, and both sides in the length direction with the leak protrusion 62 sandwiching the restriction protrusion 64. In FIG. Note that the protrusion height dimension of the restricting protrusion 64 is the same as or slightly smaller than the depth dimension of the housing recess 58 and the leak recess 62. When the projecting height dimension of the restricting protrusion 64 is smaller than the depth dimensions of the accommodating recess 58 and the leak recess 62, the projecting height dimension of the restricting protrusion 64 and the accommodating recess 58 are reduced. And the difference with the depth dimension of the leak recess 62 is made smaller than the thickness dimension of the opposing board part 82a mentioned later.

  And the upper partition member 38 and the lower partition member 40 are piled up and down, and are mutually fixed with a pin, a screw, etc. Further, the lower wall portion of the upper groove 44 of the upper partition member 38 is disposed to face the flange-like portion 52 of the lower partition member 40 so as to be spaced upward, thereby opening to the outer peripheral side and extending in the circumferential direction. A groove is formed, and the concave groove and the upper groove 44 communicate with each other at the end in the circumferential direction, so that a circumferential groove 66 extending in a spiral shape with a length of less than two laps in the circumferential direction is formed. .

  Further, the opening of the accommodation recess 58 of the lower partition member 40 is covered with the upper partition member 38, so that an accommodation space 68 is formed between the upper and lower partition members 38, 40. A first communication hole 48 is formed through the upper wall portion of the accommodation space 68, and a second communication hole 60 is formed through the lower wall portion of the accommodation space 68.

  Further, the opening of the leak recess 62 of the lower partition member 40 is covered with the upper partition member 38, so that a leak space 70 is formed between the upper and lower partition members 38, 40. The leak vacant space 70 is open to a part of the peripheral wall of the accommodating vacant space 68 and communicates with the accommodating vacant space 68. A leak hole 50 is formed through the upper partition member 38 so as to cover the leak recess 62, and the leak hole 50 communicates with the leak space 70.

Furthermore, a restricting projection 64 is provided between the accommodating cavity 68 and the leaking cavity 70, and the accommodating cavity 68 and the leaking cavity 70 are separated by a central portion in the length direction by the restricting projection 64. In addition, the opening portion of the leak space 70 to the accommodation space 68 is divided into two in the length direction with the restricting protrusion 64 interposed therebetween. Accordingly, the opening to the housing space 68 of the leakage cavity 70, the inner dimension of its length direction is the _{(L 2 -L 3) / 2} .

  The partition member 36 having such a structure is accommodated in the fluid chamber 34 and extends in the direction perpendicular to the axis, and the outer peripheral end is supported by the second mounting member 14. As a result, the fluid chamber 34 is divided into two parts up and down across the partition member 36. Above the partition member 36, a part of the wall portion is constituted by the main rubber elastic body 16, and the internal pressure is applied when vibration is input. A pressure receiving chamber 72 is formed in which fluctuations are induced. On the other hand, below the partition member 36, a part of the wall portion is formed of the flexible film 28, and an equilibrium chamber 74 is formed in which volume change is easily allowed by deformation of the flexible film 28. ing. The pressure receiving chamber 72 and the equilibrium chamber 74 are filled with the above-described incompressible fluid.

  Further, the outer peripheral surface of the partition member 36 is overlapped with the second mounting member 14 via the seal rubber layer 26, so that the outer peripheral opening of the circumferential groove 66 is covered fluid-tightly by the second mounting member 14. Thus, a tunnel-like flow path extending in the circumferential direction is formed. One end in the circumferential direction of the tunnel-shaped flow path is communicated with the pressure receiving chamber 72 through the upper communication port 46, and the other end in the circumferential direction is communicated with the equilibrium chamber 74 through the lower communication port 54. An orifice passage 76 that communicates the chamber 72 and the equilibrium chamber 74 with each other is formed by using the circumferential groove 66. The orifice passage 76 adjusts the ratio (A / L) of the passage cross-sectional area (A) and the passage length (L) while taking into account the wall spring rigidity of the pressure receiving chamber 72 and the equilibrium chamber 74, thereby making the engine shake. Is tuned to a low frequency of about 10 Hz. Further, in the present embodiment, the leak space 70 is formed closer to the upper communication port 46, which is the opening on the pressure receiving chamber 72 side of the orifice passage 76 than the accommodation space 68. An opening to the pressure receiving chamber 72 is disposed in the vicinity of the upper communication port 46.

  In the accommodation space 68, a shock absorbing rubber 78 as a cylindrical shock absorber is accommodated. As shown in FIGS. 5 to 6, the buffer rubber 78 is formed of a hollow rubber elastic body, has a substantially rectangular shape when viewed in the axial direction, and has a central hole penetrating in the short side direction. The internal space 80 is provided.

  More specifically, the shock absorbing rubber 78 is a belt-shaped cylindrical body that is flattened by crushing a cylindrical body having a substantially constant width endless in one direction, and a pair of opposed plate portions. 82a, 82b and a pair of side plate portions 84a, 84b that connect the pair of opposing plate portions 82a, 82b to each other.

  The pair of opposing plate portions 82a and 82b are plate-like bodies that have a substantially rectangular shape corresponding to each other when viewed in the axial direction, and are arranged to face each other with a predetermined distance therebetween in the vertical direction. In addition, four first window portions 86 are formed in the counter plate portion 82a, and four second window portions 88 are formed in the counter plate portion 82b. The first window portion 86 has a substantially rectangular cross section and vertically penetrates the counter plate portion 82a, and the four first window portions 86 are arranged across a crosspiece portion that is substantially cross-shaped when viewed in the axial direction. . On the other hand, the second window part 88 has a rectangular section substantially the same as the first window part 86 and vertically penetrates the counter plate part 82 b, and the four second window parts 88 are the first window part 86. Are arranged at corresponding positions.

  In addition, a pair of side plate portions 84a and 84b extending inward in the opposing direction of the pair of counter plate portions 82a and 82b are integrally formed at both ends in the long side direction of the pair of counter plate portions 82a and 82b. The pair of opposing plate portions 82a and 82b are connected to each other by the pair of side plate portions 84a and 84b. The pair of opposing plate portions 82a and 82b are connected to each other by the pair of side plate portions 84a and 84b, thereby forming a band-shaped cylindrical cushioning rubber 78 and a pair of opposing plate portions 82a and 82b. An internal space 80 surrounded by the pair of side plate portions 84a and 84b is formed.

  As shown in FIG. 4, the buffer rubber 78 having such a structure is fitted into the housing recess 58 of the lower partition member 40. Then, the upper partition member 38 is overlapped and fixed to the lower partition member 40, so that the buffer rubber 78 is accommodated in the accommodation space 68, and the inner surface of the upper wall of the accommodation space 68 is covered with the opposing plate portion 82a. In addition, the inner surface of the lower wall of the accommodation space 68 is covered with a counter plate portion 82b. In the state in which the buffer rubber 78 is disposed in the accommodation space 68, the pair of side plate portions 84 a and 84 b have a predetermined gap with respect to the inner surface of the peripheral wall (the inner surfaces of both the left and right walls in FIG. 1). It is desirable that they are opposed to each other.

  Further, the first window portion 86 of the buffer rubber 78 is positioned with respect to the first communication hole 48 of the upper partition member 38 and communicated with each other, and the second window portion 88 of the buffer rubber 78 is positioned below. They are positioned with respect to the second communication hole 60 of the partition member 40 and communicate with each other. Thereby, the fluid flow path 90 which connects the pressure receiving chamber 72 and the equilibrium chamber 74 to each other includes the first and second communication holes 48 and 60, the first and second window portions 86 and 88, and the accommodation space. 68 and an internal space 80.

  A movable film 92 as a movable member is disposed on the fluid flow path 90. The movable film 92 is a substantially rectangular plate-shaped rubber elastic body integrally formed with the buffer rubber 78, and protrudes from the side plate portion 84 a to the internal space 80 and extends in a direction substantially perpendicular to the axis. Further, as shown by a broken line in FIG. 5, the movable film 92 includes four first window portions 86 and four second windows in the long side direction and the short side direction of the opposing plate portions 82a and 82b. The first window portion 86 and the second window portion 88 are entirely overlapped with the movable film 92 in the axial projection. The movable film 92 extends between the opposing surfaces of the opposing plate portion 82a and the opposing plate portion 82b, and spreads away from both of the opposing plate portions 82a and 82b. In the present embodiment, the movable film 92 is thinner than the opposing plate portions 82a and 82b, and is easily elastically deformed.

  Further, the movable film 92 is disposed so as to spread substantially orthogonally to the fluid flow path 90 extending in the axial direction in the state where the movable film 92 is disposed in the accommodation space 68 together with the buffer rubber 78. The fluid pressure of the pressure receiving chamber 72 is exerted on the upper surface of the movable film 92 through the first communication hole 48 and the first window portion 86, and the second communication hole 60 and the second window portion are disposed on the lower surface of the movable film 92. The hydraulic pressure of the equilibrium chamber 74 is exerted through 88. Thereby, the movable film 92 is slightly deformed up and down in the internal space 80 based on the relative pressure fluctuation between the pressure receiving chamber 72 and the equilibrium chamber 74.

  Furthermore, since the movable film 92 is accommodated in the internal space 80 of the buffer rubber 78, the opposing plate portions 82 a and 82 b of the buffer rubber 78 are brought into contact with the movable film 92 on the inner surface of the wall of the storage space 68. Are placed one on top of the other. Thereby, the impact force when the movable film 92 abuts against the inner wall surface of the accommodation space 68 is relaxed based on the internal friction of the buffer rubber 78 and the like, and the hitting sound is reduced. Since the shock absorbing rubber 78 has a cylindrical shape and the movable film 92 is disposed in the inner space 80 which is a central hole, the movable film 92 is against the inner wall surfaces on both the upper and lower sides of the accommodation space 68. The impact force at the time of hitting is reduced by the buffer rubber 78, and the hitting sound is more effectively prevented.

  When a medium-frequency small-amplitude vibration corresponding to idling vibration is input, the movable film 92 is slightly displaced up and down within the internal space 80, so that the hydraulic pressure is transmitted between the pressure receiving chamber 72 and the equilibrium chamber 74. It is like that. On the other hand, at the time of inputting low-frequency large-amplitude vibration, the fluid film 90 is blocked by the movable film 92 closing either the first window portion 86 or the second window portion 88, and the fluid passage 90 is passed through. By preventing the transmission of the hydraulic pressure, the anti-vibration effect due to the fluid flow through the orifice passage 76 is effectively exhibited. In short, in the present embodiment, the hydraulic pressure transmission mechanism that transmits the hydraulic pressure of the pressure receiving chamber 72 to the equilibrium chamber 74 when the medium frequency small amplitude vibration is input includes the movable film 92. In the present embodiment, the tuning frequency of the fluid flow path 90 is set to a medium frequency range corresponding to idling vibration, but can also be set to a high frequency range corresponding to traveling noise and the like.

  Further, the shock-absorbing rubber 78 in the form of a belt-shaped cylindrical body is disposed so as to open in the short side direction of the accommodation space 68, and one opening of the shock-absorbing rubber 78 faces the leak space 70. Opened, the internal space 80 of the buffer rubber 78 is communicated with the leak space 70. The leak space 70 is always in communication with the pressure receiving chamber 72 through the leak hole 50, and is in communication with the equilibrium chamber 74 through the internal space 80, the second window 88, and the second communication hole 60. It is like that. As a result, the short-circuit passage 94 that connects the pressure receiving chamber 72 and the equilibrium chamber 74 to each other includes the leak hole 50, the leak space 70, the internal space 80, the second window 88, and the second communication hole. 60. As described above, since the intermediate portion of the short-circuit passage 94 includes the leak space 70 and the internal space 80 that are directly communicated with each other, the passage cross-sectional area of the short-circuit passage 94 can be easily ensured to be large. Can do.

  When a negative pressure is applied to the pressure receiving chamber 72, the movable film 92 is sucked toward the pressure receiving chamber 72 as shown in FIG. 7, and the first window 86 is blocked by the movable film 92. At the same time, the second window 88 is held in communication. As a result, the fluid flow path 90 is shut off and the short-circuit passage 94 is held in communication, and the fluid flows from the equilibrium chamber 74 to the pressure receiving chamber 72 through the short-circuit passage 94. As a result, the negative pressure in the pressure receiving chamber 72 is reduced, and the generation of abnormal noise due to cavitation is prevented. In addition, since the passage cross-sectional area of the short-circuit passage 94 is easily set large, it is easy to secure the amount of fluid flowing through the short-circuit passage 94, and the negative pressure of the pressure receiving chamber 72 is reduced by the fluid flow through the short-circuit passage 94. The pressure is quickly reduced, and cavitation noise is effectively prevented.

Therefore, in the engine mount 10, the short-circuit passage 94 is stably maintained in a communication state when the pressure in the pressure receiving chamber 72 is reduced. That is, the depth dimension d of the leak space 70 is set to be larger than the total thickness t of the movable film 92 and the opposing plate portion 82a: t, regardless of the change in the vertical position due to the elastic deformation of the movable film 92. Instead, the leak void 70 is maintained in communication with the internal void 80. Furthermore, the protruding length dimension L ₄ of the movable film 92 is larger than the length dimension of the opening portion of the leak cavity 70 to the accommodation cavity 68: (L ₂ −L ₃ ) / 2, and the movable film 92 is movable. The film 92 is prevented from entering the leak void 70. Thereby, even if a negative pressure is applied to the pressure receiving chamber 72 and the movable film 92 is sucked to the pressure receiving chamber 72 side, it is possible to prevent the opening of the leak hole 50 from being blocked by the movable film 92. The short-circuit passage 94 is maintained in a communication state.

Further, the inside dimension in the length direction of the leak space 70: L ₂ is made smaller than the inside dimension in the length direction of the accommodation space 68: L ₁ , so that the leak space 70 is in the middle in the length direction of the accommodation space 68. The movable film 92 is provided so as to straddle in the length direction of the opening to the accommodation space 68 of the leak space 70. As a result, even if the protruding tip portion of the movable film 92 that tends to increase in displacement due to elastic deformation is displaced so as to protrude outward in the axial direction from the opening portion of the buffer rubber 78, The abutment prevents entry into the leak space 70.

  Furthermore, a restricting protrusion 64 is provided between the accommodating space 68 and the leak space 70, and the restricting protrusion 64 is located on the middle side of the movable film 92. The movable film 92 protruding outward in the axial direction from the internal space 80 is more advantageously prevented from entering the leak space 70 by abutting against the limiting protrusion 64. In particular, in the present embodiment, since the leak hole 50 is disposed on the opposite side of the accommodation space 68 with the restricting protrusion 64 interposed therebetween, the leak hole 50 is more reliably prevented from being blocked by the movable film 92.

  As described above, the movable film 92 is prevented from entering the leak space 70 and the leak hole 50 is always kept in communication, so that the negative pressure is applied to the pressure receiving chamber 72 through the short-circuit passage 94. Fluid flow is allowed stably, and cavitation noise is prevented by reducing negative pressure. In addition, since the short circuit path 94 can be secured without restricting the elastic deformation of the movable film 92, the anti-vibration effect (vibration insulation effect by the low dynamic spring) exhibited by the elastic deformation of the movable film 92 is also effective. Can get to.

  Further, not only the movable film 92 is prevented from entering the leak void 70 but also the buffer rubber 78 disposed in a non-adhesive manner with respect to the accommodation void 68 is prevented from entering the leak void 70. Therefore, positioning means such as adhesion and locking for positioning the buffer rubber 78 in the accommodation space 68 is not required, and the structure can be simplified and the buffer rubber 78 can be easily arranged.

  Further, when a negative pressure is applied to the pressure receiving chamber 72 so as to cause cavitation, the movable film 92 is displaced toward the counter plate portion 82a, so that the counter plate portion 82b of the cylindrical buffer rubber 78 and the movable film 92 are displaced. The space between the facing and the surface expands rapidly. In this case, when the buffer rubber 78 is disposed in a non-adhesive manner with respect to the accommodation space 68, the counter plate is arranged so as to compensate the negative pressure between the counter surfaces of the counter plate portion 82 b and the movable film 92. The portion 82b is sucked and displaced toward the counter plate portion 82a. The displacement of the counter plate portion 82b is not immediately stopped at the neutral position where the negative pressure is eliminated, but is maintained from the neutral position to the counter plate portion 82a side by inertia. As a result, positive pressure acts between the opposing plate portion 82b and the movable film 92, so that the fluid between the opposing surfaces of the opposing plate portion 82b and the movable film 92 enters the leak space 70 from the opening of the buffer rubber 78. It is discharged toward the pressure receiving chamber 72 through the leak hole 50. As described above, since the buffer rubber 78 has a cylindrical shape, a further improvement in the effect of reducing cavitation noise can be expected even by a pump action using elastic deformation of the buffer rubber 78.

  In the present embodiment, the opening on the pressure receiving chamber 72 side of the leak hole 50 is disposed in the vicinity of the upper communication port 46 of the orifice passage 76. As a result, fluid is supplied from the equilibrium chamber 74 to the vicinity of the upper communication port 46 of the orifice passage 76 where the generation of bubbles due to cavitation is likely to be a problem, and the negative pressure at that location is quickly reduced. It is possible to more effectively prevent the generation of bubbles and abnormal noise resulting therefrom.

  FIG. 8 shows a lower partition member 100 and a buffer rubber 78 that constitute an engine mount as a second embodiment of the present invention. In the following description, members and parts that are substantially the same as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted. In addition, substantially the same structure as that of the first embodiment is adopted for portions not shown in the drawing.

More specifically, the lower partition member 100 has a leak recess 102. The leak recess 102 is a recess that opens in the center upper surface of the lower partition member 100 and extends to the side in the short side direction of the housing recess 58 and has the same inner dimensions as the housing recess 58 in the depth direction. It is formed with. Further, in the leak recess 102 of the present embodiment, the inner dimension L _{5 in} the length direction is substantially the same as the inner dimension L ₁ in the length direction of the housing recess 58. Then, the opening to the accommodation recess 58 of the leak recess 102 is bisected by the restricting projection 64 provided at substantially the center in the length direction, and the inner dimension in the length direction of each opening: (L ₅ − L ₃ ) / 2 is made smaller than the dimension of the movable film 92 in the length direction: L ₄ .

  Also in the structure shown in this embodiment, the movable film 92 and the buffer rubber 78 are prevented from entering the leak recess 102, and the leak hole 50 is always kept in communication. It is possible to prevent the short-circuit path 94 from being interrupted when negative pressure is applied to 72.

  Further, as is clear from the structure shown in the present embodiment, the leak space does not need to be smaller in the length direction than the accommodation space, and even if it is the same size, the leak space By making the opening to the accommodation space smaller than the movable member, it is possible to prevent the movable member from entering the leak space.

  FIG. 9 shows a lower partition member 110 constituting an engine mount as a third embodiment of the present invention in a state in which a buffer rubber 78 is disposed in the accommodation recess 58. The lower partition member 110 has a structure in which the limiting protrusion 64 is omitted as compared to the lower partition member 110 shown in the first embodiment.

  Also in the structure shown in this embodiment, the opening to the accommodation space 68 in the leak space 70 is made smaller than the movable film 92 in the length direction, and the movable film 92 is leaked to the leak space 70. In other words, the movable film 92 is prevented from entering the leak space 70 because the opening is disposed across the opening in the length direction. As a result, when the negative pressure is applied to the pressure receiving chamber 72, the short-circuit passage 94 is maintained in a communicating state, and cavitation noise is stably prevented.

  As mentioned above, although embodiment of this invention was explained in full detail, this invention is not limited by the specific description. For example, in the above-described embodiment, the accommodation recess 58 and the leak recess 62 are formed at the substantially radial center of the lower partition member 40. However, like the lower partition member 120 shown in FIG. 58 and the leak recess 62 may be provided at a position biased toward the outer peripheral side.

  In addition, as long as the leak hole 50 is provided so as to communicate the leak void 70 with the pressure receiving chamber 72, the position of the leak hole 50 is not particularly limited, and the accommodation void 68 is not necessarily sandwiched by the limiting protrusion 64. It may not be arranged on the opposite side. Specifically, for example, like the upper partition member 130 shown in FIG. 11, the leak hole 50 is adjacent to the restricting protrusion 64 in the length direction to the accommodation cavity 68 of the leak cavity 70. It may be provided near the opening.

  In addition, the leak space does not necessarily have to be formed with the same depth as the accommodation space, and communicates with the internal space of the cylindrical buffer body when the negative pressure is applied to the pressure receiving chamber (when the pressure is reduced). As long as this is the case, it may be formed with a depth dimension smaller than the accommodation space. The state of communication between the leak space and the internal space of the cylindrical shock absorber when negative pressure is applied to the pressure receiving chamber is determined when the movable member is in contact with the opposing plate portion on the pressure receiving chamber side. This is realized by setting the dimensions of each part so that the inner wall surface on the equilibrium chamber side is positioned between the movable member and the counter plate part on the equilibrium chamber side.

  The axial projection shape of the leak space is not necessarily limited to a rectangle, and may be, for example, a semicircular shape.

  In addition, when the inside dimension in the length direction of the leak space is smaller than that of the storage space, the leak space is preferably arranged in the middle of the length of the storage space, but there is a limitation. It may be arranged at the end in the length direction.

  Further, a plurality of leak vacant spaces may be formed, and each may be communicated with the accommodating vacant space. Further, a plurality of leak holes and limiting protrusions may be provided, and a plurality of leak holes and limiting protrusions may be provided in one leak space, or one each in a plurality of leak spaces. Leak holes and limiting protrusions may be provided one by one, and a plurality of leak holes and limiting protrusions may be provided as a whole.

  In the above embodiment, the movable film 92 integrally formed with the buffer rubber 78 is illustrated as the movable member. However, a movable plate separate from the buffer rubber 78 is provided in the internal space 80 with the buffer rubber 78. The structure may be arranged so as to be independently displaceable.

  Further, the cylindrical shock absorber is not limited to a continuous cylindrical shape without being interrupted as a whole, and may be divided, for example, at one place or a plurality of places on the circumference as long as it is tubular as a whole. .

  The present invention is not only applied to the engine mount, but can be suitably applied to various fluid-filled vibration isolator devices including a body mount and a member mount. Further, the scope of application of the present invention is not limited to a fluid-filled vibration isolator for automobiles, and is also applicable to a fluid-filled vibration isolator used for other than automobiles, such as motorcycles, railway vehicles, and industrial vehicles. Can be done.

10: engine mount (fluid-filled vibration isolator), 12: first mounting member, 14: second mounting member, 16: main rubber elastic body, 28: flexible membrane, 36: partition member, 46: Upper communication port (communication port on the pressure receiving chamber side of the orifice passage), 50: leak hole, 64: restricting protrusion, 68: accommodating space, 70: leak space, 72: pressure receiving chamber, 74: equilibrium chamber, 78: Buffer rubber (cylindrical buffer), 80: internal space (center hole), 92: movable member, 94: short-circuit path

Claims (5)

The first mounting member and the second mounting member are elastically connected by a main rubber elastic body, and a part of the wall portion is on one side of the partition member supported by the second mounting member. A pressure receiving chamber made of a rubber elastic body is formed, and on the other side, an equilibrium chamber having a wall part formed of a flexible film is formed. Further, the pressure receiving chamber and the equilibrium chamber are formed. Are formed in the housing space formed in the partition member, and a plate-like movable member is disposed on both sides of the movable member. In the fluid-filled vibration isolator to which one of the hydraulic pressures of the equilibrium chamber is exerted,
A cylindrical buffer is disposed in the accommodation space, and the movable member is disposed in a central hole of the cylindrical buffer, and a peripheral wall of the cylindrical buffer is a wall of the storage space. While overlaid on the strike surface of the movable member on the inner surface,
A leak void is formed in the inner surface of the peripheral wall of the housing space that is overlapped with the opening end surface of the cylindrical buffer body and extends outward from the housing space, and the leak space is formed in the pressure receiving chamber. A leak hole that communicates is formed, and when the pressure receiving chamber is depressurized, a short circuit passage that communicates the pressure receiving chamber and the equilibrium chamber is formed including the leak void and the leak hole,
Further, the opening of the leaky space to the accommodation space is longer than the movable member in the length direction perpendicular to both the thickness direction of the movable member and the axial direction of the cylindrical shock absorber. A fluid-filled vibration isolator characterized by being made small.   The fluid-filled type vibration damping device according to claim 1, wherein an inner dimension in the length direction of the leak void is smaller than an inner dimension in the length direction of the accommodation void.   The fluid-filled vibration isolator according to claim 2, wherein the leak space is formed in the middle in the length direction of the accommodation space.   A restricting protrusion is formed between the leaky space and the accommodating space to separate the leaked space and the accommodating space, and an opening of the leaking space to the accommodating space is the restricting protrusion. The first and second leakage spaces are divided into both sides in the length direction, and the openings to the accommodation spaces are made smaller than the movable member in the length direction. The fluid-filled vibration isolator according to any one of the above.   The leak space is formed at a position closer to the communication port on the pressure receiving chamber side of the orifice passage than the accommodation space, and the opening of the leak hole to the pressure receiving chamber is the pressure receiving pressure of the orifice passage. The fluid-filled vibration isolator according to any one of claims 1 to 4, wherein the fluid-filled vibration isolator is disposed near a communication port on the chamber side.

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