JP3903979B2 - Pneumatic vibration type active vibration isolator - Google Patents

Description

  The present invention relates to an active vibration isolator having a fluid chamber filled with an incompressible fluid and capable of appropriately adjusting the vibration isolating characteristics by controlling internal pressure and fluid flow in the fluid chamber. In particular, the present invention relates to an active vibration isolator of a pneumatic vibration type that controls an internal pressure and a fluid flow in a fluid chamber by utilizing a fluctuation in air pressure.

  As a type of anti-vibration device as an anti-vibration coupling body or an anti-vibration support body interposed between members constituting the vibration transmission system, the first mounting member and the second mounting member that are attached to the members that are anti-vibration connected to each other The attachment members are separated from each other and connected by a main rubber elastic body interposed between them, while forming a fluid chamber in which an incompressible fluid is enclosed, and a part of the wall of the fluid chamber There is known an active vibration isolator in which the vibration isolating characteristic is adjusted by controlling the internal pressure and fluid flow of the fluid chamber by vibrating the movable member. For example, the vibration isolators described in JP-A-60-8540, JP-A-61-2939, and JP-A-61-191543 are examples thereof. Such an active vibration isolator, for example, applies a vibration force having an amplitude or a phase corresponding to the vibration to be damped to a member to be damped, thereby causing vibration in the vibration proof object. For example, the present invention can be advantageously applied to automobile engine mounts, body mounts, and the like.

  By the way, in the conventional active vibration isolator as described above, in order to vibrate the movable member, generally, an electromagnetic driving means that requires expensive and complicated parts such as a permanent magnet and a coil is employed. There was a problem that it was difficult to manufacture and an increase in size and weight was inevitable. In view of this, the present applicant previously described a working air chamber sealed on the opposite side of the fluid chamber with a movable member constituting a part of the wall portion of the fluid chamber in JP-A-9-3527 or the like. A pneumatic vibration-driven active vibration isolator has been clarified, which is configured to change the internal pressure in the fluid chamber by applying a pressure change to the working air chamber. In such an anti-vibration device, it is not necessary to incorporate an excitation means such as an electromagnetic drive unit in the anti-vibration device, the number of parts can be reduced and manufacturability can be improved, and downsizing and weight reduction can be advantageous. Can be achieved.

  By the way, in such an active vibration isolator of a pneumatic vibration type, for example, the working air chamber is connected to the switching valve through the air supply / discharge path in order to exert a pressure change on the working air chamber. By the switching operation of the switching valve, the working air chamber is alternately and repeatedly communicated with two air pressure sources having different pressures. More specifically, for example, by adopting a negative pressure source and the atmosphere as two air pressure sources, switching operation of the switching valve is performed at an appropriate cycle, and negative pressure supply to the working air chamber and release to the atmosphere are repeated. In addition, an internal pressure fluctuation or excitation force having a frequency corresponding to the switching operation cycle of the switching valve can be advantageously exerted between the fluid chamber, and thus the first mounting member and the second mounting member.

  However, when the present inventors have further studied the vibration isolator having the structure according to the earlier application, it is caused by the switching operation of the switching valve and the like, and enters the working air chamber through the air supply / discharge passage. It has been found that fluctuations in the air pressure that are exerted tend to inherently include not only the intended frequency component corresponding to the switching period of the switching valve, but also other secondary frequency components. Since the secondary frequency component is basically not correlated with the vibration component to be damped, the air pressure fluctuation having the secondary frequency component is exerted on the working air chamber. As a result, an internal pressure fluctuation having a frequency component that does not correspond to the vibration to be damped is generated in the fluid chamber, which may adversely affect the vibration proofing effect. For example, in an engine mount for automobiles, body vibration noise or noise in a frequency range other than the original vibration-proofing purpose is caused by an excitation force caused by air pressure fluctuation having a secondary frequency component being exerted on the body. There was a possibility that chatter vibrations and the like would occur, and the anti-vibration performance might deteriorate.

Japanese Patent Application Laid-Open No. 60-8540 JP 61-2939 A Japanese Utility Model Publication No. 61-191543 Japanese Patent Laid-Open No. 9-3527

  Here, the present invention has been made in the background as described above, and the problem to be solved is that air pressure fluctuations having a frequency component corresponding to a high degree to the vibration to be vibrated are applied. Provided is a pneumatic vibration isolation device capable of controlling vibration isolation characteristics with high accuracy by exerting on an air chamber, and capable of obtaining a desired vibration isolation performance advantageously and stably. There is.

In order to solve such a problem, the feature of the present invention is that the first mounting member and the second mounting member that are attached to the members that are vibration-proof connected to each other are arranged apart from each other. A fluid chamber in which an incompressible fluid is sealed is formed while being connected by a main rubber elastic body interposed therebetween, and a part of a wall portion of the fluid chamber is configured by a movable member, and the movable member A working air chamber sealed on the opposite side of the fluid chamber is formed on the opposite side, and a pressure change is applied to the working air chamber to vibrate the movable member, thereby reducing internal pressure and fluid flow in the fluid chamber. In the active vibration isolator of pneumatic vibration type that is controlled to adjust the vibration isolating characteristics, the fluid chamber has a part of a wall portion constituted by the main rubber elastic body so that a pressure change occurs when vibration is input. Main liquid chamber to be generated and the movable A part of the wall portion is made of a material and includes a sub liquid chamber communicated with the main liquid chamber through the orifice passage, and the resonance frequency of the fluid that flows through the orifice passage is such as idle vibration. It is tuned to the vibration in the medium frequency vibration region, and the internal pressure change is generated in the secondary liquid chamber by the vibration of the movable member, while the working air chamber changes the pressure in the working air chamber. Is connected to a switching valve through an air supply / exhaust passage, and the working air chamber is alternately and repeatedly communicated with two air pressure sources having different pressures by the switching operation of the switching valve. Periodic air pressure fluctuations are generated in the working air chamber, and the movable member includes a rubber elastic plate having a restoring force to a certain shape based on elasticity. On the other hand, on the air supply / exhaust path, a silencer set so as to be able to reduce air pressure fluctuations in a higher-order frequency range that deviates from the frequency of vibration to be vibrated is disposed, This is to reduce the air pressure fluctuation at a higher frequency than the basic air pressure fluctuation frequency due to switching of the switching valve.

  In the active vibration isolator of the pneumatic vibration type constructed according to the present invention as described above, the damping effect of the air pressure fluctuation by the silencer disposed on the air supply / discharge path does not correspond to the vibration to be vibrated. Air pressure fluctuations with frequency components are reduced on the air supply / exhaust path leading to the working air chamber, so that transmission of such frequency components to the working air chamber, and hence vibration deterioration in the vibration-proof object is reduced or prevented. The Rukoto. Furthermore, the silencer can suppress the damping effect of the frequency component corresponding to the vibration to be damped to a low level by adjusting its characteristics appropriately. In contrast, an effective anti-vibration effect is stably exhibited.

  Further, an active vibration isolator of a pneumatic vibration type structured according to the present invention includes a vibration isolator main body configured to include first and second mounting members, a main rubber elastic body, a fluid chamber, and the like, The air pressure source and the like can be realized by an extremely simple and simple configuration by adding a silencer on the air supply / exhaust path without any special modification, and there is also an advantage that it is easy to put into practical use. is there.

  In the present invention, any silencer may be used as long as it can exhibit a damping effect against air pressure fluctuations in a specific frequency range. In addition to a conventionally known resonator type (resonance type), a cavity type or an interference type may be used. Various types such as molds can be used singly or in combination. In particular, the damping effect on the air pressure fluctuation of the frequency component corresponding to the vibration to be damped can be reduced. What can be set sufficiently lower than the damping effect on is desirable. Furthermore, a plurality of silencers can be arranged on the air supply / discharge path, and at this time, different frequency characteristics of the air pressure fluctuation attenuation effect may be set for each silencer. In addition, the form and material of the air supply / discharge path are not particularly limited, but the material has sufficient deformation strength against the air pressure fluctuation exerted, and at least strength sufficient to prevent blockage due to deformation. For example, metal, resin, rubber or the like is employed. Here, when the air supply / discharge path is elastically deformed by air pressure fluctuation, there is a possibility that secondary air pressure fluctuation caused by the elastic deformation of the air supply / discharge path may be caused, but the structure according to the present invention is adopted. In the active vibration isolator, an effective reduction effect can be obtained by such a silencer even for such air pressure fluctuations.

  In the active vibration isolator having a structure according to the present invention, for example, the working air chamber is connected to a pressure control type air pressure source such as an air cylinder mechanism through the air supply / discharge passage. However, it is preferable that the working air chamber is connected to a switching valve through an air supply / exhaust passage, and the working air chamber has a pressure different from each other by the switching operation of the switching valve. By alternately and repeatedly communicating with two air pressure sources having a pressure, a pressure change is caused in the working air chamber. Note that it is effective to employ a suitable combination of negative pressure, positive pressure and atmospheric pressure as the air pressure source. Further, as the switching valve, a solenoid valve or the like is preferably employed because it is easy to control and has excellent responsiveness.

  As described above, if a plurality of air pressure sources are alternately communicated to the working air chamber by the switching valve, it is possible to change the air pressure in the working air chamber with a very simple structure. In the anti-vibration device for use, by using the negative pressure and the atmospheric pressure generated in the intake system of the internal combustion engine, it is not necessary to provide a special air pressure source, and simplification of the structure is advantageously achieved.

  In addition, as a result of investigation by the present inventor, when the pressure change is generated in the working air chamber by causing the working air chamber to alternately communicate with different air pressure sources by the switching operation of the switching valve, Since the air pressure in the air supply / discharge path is distorted due to the ON / OFF (open / close) control of the switching operation in a pulsed manner, the air pressure exerted on the working air chamber should be isolated from vibration. It was recognized that secondary frequency components that do not correspond to vibrations are likely to travel, but in that case, the present invention is applied, and as described above, the silencer is disposed on the air supply / discharge path, which is extremely excellent. The anti-vibration effect can be exhibited stably.

  Further, in the active vibration isolator having a structure according to the present invention, the movable member may be any member as long as it can exert the pressure fluctuation of the working air chamber on the fluid chamber based on the displacement or deformation thereof. A movable member configured to include a rubber elastic plate having a restoring force to a certain shape based on elasticity is suitably employed. If such a movable member is employed, the movable member is returned to and held at a substantially constant position in a state where the air pressure exerted on the working air chamber is released, so that the internal pressure of the fluid chamber can be easily controlled. In addition, when the air pressure exerted on the working air chamber is released, the movable member is returned to a predetermined position. For example, as the air pressure exerted on the working air chamber, only one of the negative pressure and the positive pressure is used. Adopting fluctuating air pressure or fluctuating air pressure by switching between one of negative pressure or positive pressure of a certain magnitude and atmospheric pressure, etc., it is possible to vibrate the movable member advantageously. . In addition, in order to assist the restoring force to a certain shape based on the elasticity of the movable member, it is possible to provide a biasing means that constantly applies a biasing force in a specific direction to the movable member. If a spring or the like is employed, the restoring property of the movable member to a certain shape can be obtained very advantageously and stably over a long period of time.

  Further, in the active vibration isolator having a structure according to the present invention, the specific structure of the fluid chamber is not particularly limited, and an internal pressure fluctuation is generated in the fluid chamber by applying a pressure change to the working air chamber. Any anti-vibration characteristic can be realized based on the pressure change in the fluid chamber and the fluid flow action in the fluid chamber. Specifically, for example, such a fluid chamber includes a main liquid chamber in which a part of the wall portion is configured by the main rubber elastic body and an internal pressure fluctuation is generated at the time of vibration input. A structure is adopted in which another portion of the wall portion is constituted by a movable member, and the internal pressure fluctuation is directly generated in the main liquid chamber by the vibration of the movable member. If such a fluid chamber structure is employed, the vibration isolation characteristics can be controlled by directly controlling the internal pressure of the main liquid chamber by the vibration of the movable member.

  In addition, the fluid chamber includes a main liquid chamber in which a part of the wall portion is configured by the main rubber elastic body and a pressure change is generated at the time of vibration input, and a part of the wall portion is configured by the movable member and passes through the orifice passage. A structure in which a sub liquid chamber communicated with the main liquid chamber is included so that a change in internal pressure is generated in the sub liquid chamber by the vibration of the movable member may be employed. If such a fluid chamber structure is adopted, the pressure fluctuations in the main liquid chamber due to vibration input will occur because the movable member is vibrated and the pressure change is exerted on the sub liquid chamber by exerting air pressure fluctuations on the working air chamber. In consideration of the above, by controlling the internal pressure of the secondary liquid chamber by exciting the movable member with an appropriate phase difference with respect to the input vibration, the flow of fluid flowing through the orifice passage and the main liquid chamber through the orifice passage are controlled. Based on the internal pressure control, the desired vibration isolation characteristics can be obtained advantageously.

  At that time, if the resonance action of the movable member is used, the movable member can be more efficiently vibrated to obtain more excellent vibration isolation performance. Alternatively, the fluid chamber includes a main liquid chamber in which a part of the wall is configured by the main rubber elastic body and a pressure change is generated when vibration is input, while a part of the wall is a flexible membrane. The structure is formed by forming an equilibrium chamber in which an incompressible fluid is sealed, and a fluid communication path that allows the equilibrium chamber to communicate with the main liquid chamber. It is also possible.

  If such a fluid chamber structure and an equilibrium chamber are adopted, a pressure change is generated in the main liquid chamber at the time of vibration input, resulting in a pressure difference between the main liquid chamber and the equilibrium chamber. The fluid flow through the fluid communication path is generated, and an effective vibration-proofing effect is exhibited based on the fluid action such as the resonance action of the fluid flowed through the fluid communication path.

  In the pneumatic vibration type active vibration isolator having the structure according to the present invention as described above, it is not necessary to incorporate a special member to configure the actuator means for exciting the movable member, and it can be applied from the outside. Since the movable member is vibrated based on the air pressure exerted on the air chamber, the active vibration isolator capable of controlling the vibration isolating characteristics can be advantageously realized with a simple structure and a small number of parts.

  Moreover, in such an active vibration isolator of the pneumatic vibration type, the fluctuation of the air pressure in the frequency range that does not correspond to the vibration to be vibrated in the vibration isolating object with respect to the air pressure fluctuation exerted on the working air chamber through the air supply / discharge path However, even if for some reason, the air pressure fluctuation in other frequency ranges can be reduced by the silencer. On the other hand, it can be done with high accuracy, and thereby adverse effects on vibrations in other frequency ranges can be avoided very advantageously, and the effective anti-vibration effect is stabilized against vibrations to be isolated. Can be demonstrated.

  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 and FIG. 2 respectively show an overall schematic diagram and an explanatory view of a main part of an active vibration isolator constituting an automobile engine mount as a first embodiment of the present invention. This active vibration isolator includes a mount body 10 and air pressure control means for causing a change in air pressure to the mount body 10 to generate a vibration force. The mount body 10 includes a first mounting member 14 as a first mounting member that is mounted on the power unit 12 of the automobile, and a second mounting as a second mounting member that is mounted on the body 16 of the automobile that is the object of vibration isolation. The metal fitting 18 is elastically connected by a main rubber elastic body 20 interposed therebetween, and is interposed between the power unit 12 and the body 16 to support the vibration of the power unit 12 with respect to the body 16. It is supposed to squeeze. The air pressure control means changes the air pressure with respect to the working air chamber 22 formed in the mount body 10 using the negative pressure generated in the intake system of the internal combustion engine of the automobile and the atmospheric pressure as air pressure sources. As a result, an excitation force is generated in the mount body 10 and the excitation force is transmitted to the body 16, and the magnitude of the air pressure fluctuation exerted on the working air chamber 22 according to the vibration to be vibration-isolated By adjusting the phase and the like by the control device 24, the vibration in the body 16 is actively suppressed. Note that the mount body 10 of the present embodiment is capable of exhibiting an effective anti-vibration effect against vertical vibrations in FIGS. 1 and 2.

  More specifically, the first mounting bracket 14 constituting the mount body 10 has a substantially truncated cone shape, and a mounting screw portion 26 protruding upward in the axial direction is formed at the large-diameter end thereof. Are integrally formed. And the 1st attachment metal fitting 14 is attached to the power unit 12 side of a motor vehicle by this attachment screw part 26, as FIG. 1 shows. The main rubber elastic body 20 has a substantially frustoconical shape, and is vulcanized and bonded to the small diameter side end portion with the first mounting bracket 14 being embedded in the axial direction. . A cylindrical connecting fitting 28 is vulcanized and bonded to the outer peripheral surface of the large-diameter end of the main rubber elastic body 20. The main rubber elastic body 20 is formed with a recess 30 that opens to the end surface on the large diameter side.

  On the other hand, the second mounting bracket 18 has a large-diameter cylindrical shape as a whole, and the large-diameter portion 34 is formed on the upper side in the axial direction across the step portion 32 formed in the intermediate portion in the axial direction. In addition, the lower side in the axial direction is a small diameter portion 36. The second mounting bracket 18 is attached to the body 16 side of the automobile as shown in FIG. 1 via a bracket (not shown) that is externally fixed to the large diameter portion 34. Yes. A thin seal rubber layer 38 is provided on each inner peripheral surface of the large diameter portion 34 and the small diameter portion 36, and a thin circle as a flexible film is formed in the opening on the small diameter portion 36 side. A plate-shaped rubber elastic film 40 is disposed, and the outer peripheral edge of the rubber elastic film 40 is vulcanized and bonded to the inner peripheral surface of the small diameter part 36, so that the opening on the small diameter part 36 side is rubber. The elastic membrane 40 is fluid-tightly closed.

  The second mounting bracket 18 is attached to the large-diameter side end of the main rubber elastic body 20 by inserting the large-diameter portion 34 into the coupling bracket 28 and fluid-tightly fixing it. Yes. As a result, the first mounting bracket 14 and the second mounting bracket 18 are elastically coupled via the main rubber elastic body 20 and the opening on the large diameter portion 34 side of the second mounting bracket 18. The portion is covered fluid-tightly by the main rubber elastic body 20, and therefore, inside the second mounting bracket 18, including the inside of the recess 30 provided in the main rubber elastic body 20, a sealed region Is formed.

  Further, a partition member 42 is accommodated in the small diameter portion 36 of the second mounting bracket 18. The partition member 42 has a circular block shape as a whole, and is fitted and fixed fluid-tightly to the inner peripheral surface of the small diameter portion 36. The partition member 42 partitions the sealed region formed inside the second mounting bracket 18 on both axial sides (the main rubber elastic body 20 side and the rubber elastic film 40 side). Accordingly, a part of the wall portion is configured by the main rubber elastic body 20 on the upper side in the axial direction from the partition member 42, and an internal pressure change is caused based on elastic deformation of the main rubber elastic body 20 at the time of vibration input. The main liquid chamber 44 is formed on the lower side in the axial direction than the partition member 42, and a part of the wall portion is constituted by the rubber elastic film 40, and the deformation is caused by the deformation of the rubber elastic film 40. An equilibrium chamber 46 in which the volume change is easily allowed is formed. The main liquid chamber 44 and the equilibrium chamber 46 are filled with incompressible fluid such as water, alkylene glycol, polyalkylene glycol, or silicone oil.

  Here, the partition member 42 includes an outer wall member 50 having a substantially thick bottomed cylindrical shape provided with a central concave portion 48 that opens upward in the axial direction, and is integrated with an opening-side end portion of the outer wall member 50. The formed outer flange portion 52 is superimposed on the stepped portion 32 of the second mounting bracket 18 and sandwiched between the main rubber elastic body 20 and fixedly assembled to the second mounting bracket 18. It has been. In addition, a concave groove 54 that is open to the outer peripheral surface and extends in the circumferential direction is formed in the peripheral wall portion of the outer wall member 50, and the concave groove 54 is covered with the small diameter portion 36 of the second mounting bracket 18. As a result, the main liquid chamber 44 and the equilibrium chamber 46 communicate with each other, and a fluid communication path 56 that allows fluid flow between the chambers 44 and 46 is formed. In the present embodiment, the length of the fluid communication path 56 is set so that an effective vibration-proofing effect against low-frequency vibration is exhibited based on the resonance action of the fluid flowing through the fluid communication path 56. The cross-sectional area is set.

  A rubber elastic plate 58 and a lid member 60 as movable members are sequentially fitted in the central recess 48 of the outer wall member 50 in the axial direction and fixedly assembled to the outer wall member 50. The rubber elastic plate 58 has a thick disk shape, and a portion of the outer peripheral edge portion extending over a predetermined width is inclined downward in the axial direction toward the outer peripheral side. The fitting ring 62 is vulcanized and bonded. Then, when the fitting ring 62 is press-fitted into the central recess 48 of the outer wall member 50 and fixed, the rubber elastic plate 58 spreads in the direction perpendicular to the axis at the bottom of the central recess 48 and the central portion is the central recess 48. It is positioned so as to be spaced apart upward from the bottom surface, and is arranged in a state in which elastic deformation or elastic displacement is allowed. The lid member 60 has a thick disk shape, and is press-fitted into the central concave portion 48 of the outer wall member 50 so as to be fitted and fixed to cover the opening of the central concave portion 48. It is installed.

The opening of the central recess 48 is covered with a lid member 60 and the inside thereof is fluid-tightly partitioned by a rubber elastic plate 58, so that the rubber elastic plate 58 and the lid member are formed in the central recess 48. A sub liquid chamber 64 is formed which is located between 60 and in which the same incompressible fluid as the main liquid chamber 44 is enclosed. Further, the cover member 60 is formed with a circumferential groove 66 that is open on the outer peripheral surface and extends in the circumferential direction. The circumferential groove 66 is covered with the peripheral wall portion of the outer wall member 50, thereby the main liquid chamber 44 and An orifice passage 68 is formed which communicates the sub liquid chamber 64 with each other and allows fluid flow between the chambers 44 and 64. In this embodiment, the resonance frequency of the fluid that flows through the orifice passage 68 is set higher than the resonance frequency of the fluid that flows through the fluid communication passage 56 that connects the main liquid chamber 44 and the equilibrium chamber 46. . Specifically, for example, fluid communication passage 56 side to the frequency vibration range in the idle vibration or the like orifice passage 68 side to the low-frequency vibration range such as shake, are their respective tuning.

  Furthermore, the working air chamber 22 is formed which is located on the opposite side of the sub liquid chamber 64 with the rubber elastic plate 58 interposed therebetween and is sealed with respect to the external space. The outer wall member 50 is formed with an air communication passage 70 extending radially between the working air chamber 22 and the equilibrium chamber 46, and an inner end portion of the air communication passage 70 is formed on the bottom surface of the central recess 48. While being opened and communicating with the working air chamber 22, the outer end portion of the air communication passage 70 is formed in the peripheral wall portion of the outer wall member 50 and penetrates through the second mounting bracket 18 to open to the outer peripheral surface. The port 72 communicated with each other.

  The mount main body 10 is connected to air pressure control means for switching and controlling the vibration isolation characteristics of the mount main body 10 in the mounted state as described above. That is, when the mount body 10 is mounted, an air supply / discharge path 74 is connected to the port 72 provided in the mount body 10, and the working air chamber 22 is connected to the negative pressure pump through the air supply / discharge path 74. And a negative pressure tank 76 that stores negative pressure generated by a negative pressure source such as an intake system of an internal combustion engine. Further, a switching valve 78 is provided on the air supply / discharge path 70 that connects the port 72 to the negative pressure tank 76, and by the switching operation of the switching valve 78, the working air chamber 22 is connected to the negative pressure tank 76. It is alternatively connected to the atmosphere. As the switching valve 78, an electromagnetic valve that can be switched at a high speed is preferably employed.

  As a result, periodic air pressure fluctuations are generated in the working air chamber 22 by switching the switching valve 78 at an appropriate cycle. The rubber elastic plate 58 is positioned above (sub liquid chamber 64 side) in a state where the working air chamber 22 is connected to the atmosphere, based on a balance with a restoring force or the like due to elasticity of the rubber elastic plate 58 itself. Although being held in a squeezed state, when a negative pressure is applied to the working air chamber 22, the rubber elastic plate 58 is displaced downward (to the working air chamber 22 side) against the restoring force due to the elasticity. In addition, when the negative pressure of the working air chamber 22 is released from this state, the rubber elastic plate 58 is restored and displaced upward (on the side of the sub liquid chamber 64) based on the restoring force due to elasticity. As a result, the rubber elastic plate 58 is reciprocated up and down (vibrated) in accordance with the valve operation of the switching valve 78.

  That is, when the rubber elastic plate 58 is vibrated in this way, the internal pressure of the sub liquid chamber 64 is changed and the internal pressure difference with the main liquid chamber 44 is positively generated. The fluid through the orifice passage 68 between the sub liquid chamber 64 and the main liquid chamber 44 is generated by exciting the rubber elastic plate 58 at a frequency corresponding to the input vibration to cause an internal pressure fluctuation in the sub liquid chamber 64. The flow is actively generated. As a result, the amount of fluid flow through the orifice passage 68 is advantageously ensured, and the vibration isolation effect based on the fluid action such as the resonance action of the fluid can be exhibited extremely effectively. Further, in the resonance frequency range of the fluid flowing through the orifice passage 68, the internal pressure control of the main liquid chamber 44 can be performed very efficiently based on the resonance action of the fluid. A small change in internal pressure, in other words, a small change in air pressure in the working air chamber 22, may cause a large internal pressure fluctuation in the main liquid chamber 44, thereby generating an exciting force that counteracts vibrations of the body 16. It can be done. As is clear from this, in the mount main body 10 of the present embodiment, the fluid chamber is configured including the main liquid chamber 44 and the sub liquid chamber 64.

  The air pressure fluctuation generated in the working air chamber 22 and the internal pressure fluctuation generated in the auxiliary liquid chamber 64 correspond to the magnitude and phase of the air pressure exerted on the working air chamber 22. Therefore, when the switching operation of the switching valve 78 is controlled by the control device 24, the phase and magnitude of the air pressure exerted on the working air chamber 22 takes into account the pressure transmission time to the main liquid chamber 44, and the like. Thus, it is controlled so as to have an appropriate magnitude with an appropriate phase difference with respect to the input vibration. As the control method, feedback control such as adaptive control that minimizes the error signal, map control based on a predetermined set value, or the like can be employed. Specifically, for example, based on vehicle state signals such as engine speed, shift position, air conditioner switch state, etc., the frequency, amplitude, phase, etc. of the body vibration in question are determined from data obtained in advance. The control device 24 generates a switching control signal for the switching valve 78 so that an excitation force that counteracts the body vibration in an opposite phase to the body vibration is exerted on the body 16, and an amplifier or the like is generated as necessary. The switching valve 78 is switched at an appropriate cycle and phase according to the control signal so that an effective damping effect is exhibited. It has become.

  Further, the air supply / discharge path 74 is provided with a silencer 82 located on the mount body 10 side of the switching valve 78 on the transmission path of the variable air pressure generated by the switching operation of the switching valve 78. Is provided. The silencer 82 is opened and communicated with the peripheral wall surface of the air supply / discharge passage 74, branches from the air supply / discharge passage 74, extends at a predetermined length: L, and has a distal end portion hermetically sealed by the lid 84. It is comprised by the hollow tube body 86 obstruct | occluded by. Thus, as is well known, the silencer 82 is appropriately adjusted in the length: L of the hollow tube body 86, so that the frequency (frequency) region corresponding to the length: L is adjusted. With respect to the air vibration (air pressure fluctuation), an effective reduction effect based on the resonance damping action of the wave can be exhibited.

  Here, the length L of the hollow tubular body 86 is not reduced as much as possible with respect to the air pressure fluctuation corresponding to the vibration frequency to be vibrated in the body 16, and other air pressure fluctuations, That is, the body 16 is adjusted so as to exhibit an effective reduction effect as much as possible with respect to air pressure fluctuations that do not correspond to the vibration frequency to be suppressed. Specifically, for example, depending on the pulse-like switching operation of the switching valve 78, the air supply / discharge path 74 has a higher order (for example, secondary or 3rd order) than the basic air pressure fluctuation frequency due to switching of the switching valve 78. The following high frequency components are likely to occur, and this higher order component deviates from the ideal sinusoidal air pressure fluctuation. Therefore, the length L of the hollow tubular body 86 is set so that an effective reduction effect can be exhibited.

  Therefore, in the vibration isolator having the above-described structure, among the air pressure fluctuations exerted on the working air chamber 22 through the air supply / discharge passage 74, noiseless air pressure fluctuations that do not correspond to body vibrations are reduced or reduced by the silencer 82. Is eliminated, the air pressure variation corresponding to the body vibration to be vibrated is effectively exerted on the working air chamber 22, and only the internal pressure variation effective for damping or preventing the body vibration is exerted. Is exerted on the sub liquid chamber 64 and the main liquid chamber 44, and problems such as the deterioration of the vibration state of the body 16 due to the excitation force caused by the fluctuation of the internal pressure in the frequency region other than the vibration suppression target are advantageously avoided. It is.

  Further, in the vibration isolator as described above, since it is not necessary to incorporate an actuator member such as an electromagnetic drive means in the mount body 10, the structure is extremely simple and easy to manufacture, and it is light, compact and inexpensive. There are advantages. In addition, since the structure is simple, it is excellent in durability and reliability, and there is an advantage that it is easy to deal with even when a failure occurs.

  Further, in such a vibration isolator, the internal pressure fluctuation is generated in the sub-liquid chamber 64 and the main liquid chamber 44 by vibrating the rubber elastic plate 58 using negative pressure. In an automobile using this, the negative pressure generated in the intake system or the like can be used advantageously, and there is an advantage that no special drive energy generating means is required. If compressed air is easily obtained, it is of course possible to vibrate the rubber elastic plate 58 using positive pressure instead of negative pressure.

  By the way, as the silencer 82 disposed on the air supply / discharge passage 74, in addition to the side branch type as described above, various silencers having various structures capable of exhibiting an effective reduction effect against air pressure fluctuations in a specific frequency range. Can be employed. Specifically, for example, as shown in FIG. 3, a resonance silencer in which a resonance box 88 of a predetermined size is provided at the tip of a branched hollow tube 86, or as shown in FIG. As shown in FIG. 5, a resonance type silencer in which a plurality of enlarged diameter portions 90 having a predetermined size are arranged in the axial direction and arranged in series with respect to the air supply / discharge passage 74. In addition, a resonance box 92 that covers the outer periphery of the air supply / discharge passage 74 is provided, and a communication hole 94 that communicates with an internal space of a predetermined size formed by the resonance box 92 is provided in the peripheral wall portion of the air supply / discharge passage 74. As shown in FIG. 6, a resonant silencer, or a hollow silencer in which an expansion box 96 having a predetermined volume is arranged in series with respect to the air supply / discharge path 74, as shown in FIG. As shown, the air supply / discharge path 7 is placed in an expansion box 98 having a predetermined volume arranged in series on the air supply / discharge path 74. As shown in FIG. 8, a hollow silencer in which an input side opening end and an output side opening end are inserted with a predetermined length, an expansion box 100 having a predetermined volume is formed at a bent portion of the air supply / discharge passage 74. As shown in FIG. 9, the cavity silencer installed substantially in series, and further, two points spaced apart in the axial direction in the air supply / discharge passage 74 are connected to the length of the air supply / discharge passage 74. Or an expansion silencer provided with a bypass conduit 102 communicating with a predetermined length different from the above, or in an expansion box 104 arranged in series on an air supply / discharge passage 74 as shown in FIG. In addition, any air outlet type silencer, in which the input side of the air supply / discharge path 74 is opened and communicated through the pore 106, can be used.

  Furthermore, the mount body also causes an internal pressure variation in the fluid chamber at a cycle corresponding to the variation cycle of the working air pressure by causing the air pressure variation to occur in the working air chamber formed inside. The anti-vibration characteristics can be changed and controlled by the fluid flow effect generated in the fluid chamber and the excitation force exerted between the first mounting member and the second mounting member due to the pressure fluctuation of the fluid chamber. Any structure may be used as long as it is an active vibration isolator body of a pneumatic vibration type, and its structure is not limited. Specifically, for example, by directly configuring a part of the wall portion of the main liquid chamber 44 with the rubber elastic plate 58, the internal pressure of the main liquid chamber 44 is increased by the displacement of the rubber elastic plate 58 that is vibrated. A mount body or the like that is directly controlled can also be used. Alternatively, as disclosed in Japanese Patent Application Laid-Open No. 9-3527, etc., the first mounting member and the outer cylinder member are separated by a shaft member and an outer cylinder member that are arranged at a predetermined distance in the direction perpendicular to the axis. The two attachment members are configured, and a main rubber elastic body is interposed between the shaft member and the outer cylinder member facing each other in the direction perpendicular to the axis, and a fluid chamber is formed between the shaft member and the outer cylinder member. A formed cylindrical mount body or the like can also be used.

  Further, a mass member made of a high specific gravity material such as a metal is fixed to the central portion of the rubber elastic plate 58, and the natural frequency of the rubber elastic plate 58 is adjusted to utilize the resonance action of the rubber elastic plate 58. Further, it is possible to improve the efficiency of pressure transmission from the working air chamber 22 to the sub liquid chamber 64.

  Further, in the air pressure control means in the above embodiment, the negative pressure tank 76 is provided on the air supply / exhaust passage 74. However, if an effective negative pressure can be obtained, such a negative pressure tank 76 is not necessarily provided. There is no.

  In addition, it goes without saying that the present invention can be similarly applied to various types of pneumatic vibration isolator other than the automobile engine mount.

  In addition, although not enumerated one by one, the present invention is not construed as being limited by the description relating to the above-described embodiment, and is implemented in a mode in which various changes, modifications, improvements, and the like are added based on the knowledge of those skilled in the art. Needless to say, any such embodiment is included in the scope of the present invention without departing from the spirit of the present invention.

1 is an overall schematic diagram schematically showing an automobile engine mount device as an embodiment of the present invention. It is explanatory drawing which shows the mount main body and pneumatic control means which are the principal parts in the engine mounting apparatus for motor vehicles shown by FIG. It is explanatory drawing which shows another specific example of the silencer which can be employ | adopted in the engine mount apparatus shown by FIG. It is explanatory drawing which shows another specific example of the silencer which can be employ | adopted in the engine mount apparatus shown by FIG. It is explanatory drawing which shows another specific example of the silencer which can be employ | adopted in the engine mount apparatus shown by FIG. It is explanatory drawing which shows another specific example of the silencer which can be employ | adopted in the engine mount apparatus shown by FIG. It is explanatory drawing which shows another specific example of the silencer which can be employ | adopted in the engine mount apparatus shown by FIG. It is explanatory drawing which shows another specific example of the silencer which can be employ | adopted in the engine mount apparatus shown by FIG. It is explanatory drawing which shows another specific example of the silencer which can be employ | adopted in the engine mount apparatus shown by FIG. It is explanatory drawing which shows another specific example of the silencer which can be employ | adopted in the engine mount apparatus shown by FIG.

Explanation of symbols

10 mount main body 12 a power unit 14 first mounting member 16 Bode over <br/> 18 second mounting member 20 the main rubber elastic body 22 working air chamber 24 controller 44 main liquid chamber 58 rubber elastic plate 64 sub liquid chamber 68 orifices Passage 74 Air supply / discharge passage 78 Switching valve 82 Silencer

Claims (5)

The first mounting member and the second mounting member that are attached to the members that are vibration-proof connected to each other are spaced apart and connected by the main rubber elastic body interposed between them, and the incompressible fluid is enclosed. Forming a fluid chamber, and forming a part of the wall of the fluid chamber with a movable member to form a working air chamber sealed on the opposite side of the fluid chamber with the movable member interposed therebetween, Pneumatic vibration type active vibration isolator which adjusts the vibration isolating characteristic by controlling the internal pressure and fluid flow in the fluid chamber by applying a pressure change to the working air chamber to vibrate the movable member. In
The fluid chamber has a main liquid chamber in which a part of the wall is configured by the main rubber elastic body and a pressure change is generated upon vibration input, and a part of the wall is configured by the movable member and passes through an orifice passage. It is configured to include a sub-liquid chamber is caused to communicate with the main liquid chamber, and the resonance frequency of fluid flowing through the orifice passage, in being tuned to the vibration of frequency vibration range consisting of idling vibration, the movable member the vibration being adapted to the internal pressure change is caused in the sub liquid chamber by and said working air chamber through the air supply and discharge passage on a pressure change in the air chamber for the acting, is connected to the switching valve By the switching operation of the switching valve, the working air chamber is alternately and repeatedly communicated with two air pressure sources having different pressures, whereby periodic air is supplied to the working air chamber. With change is adapted to be caused, the movable member is configured to include the rubber elastic plate having a restoring force to a predetermined shape based on the elastic, the air supply and discharge path, to be damped A silencer that is set so as to reduce the air pressure fluctuation in the higher frequency range that deviates from the frequency of vibration is disposed, and the higher frequency than the basic air pressure fluctuation frequency by switching the switching valve. A pneumatic vibration type active vibration isolator characterized by reducing air pressure fluctuation.
  The silencer is configured by providing a hollow tube whose end is hermetically closed so as to communicate with the air supply / discharge passage, and the length of the hollow tube is to be vibration-proof. 2. An active vibration isolator of pneumatic excitation type according to claim 1, which is adjusted so as to reduce air pressure fluctuation in a higher-order frequency range that is out of the frequency of vibration. The sub liquid chamber is formed on the opposite side of the main liquid chamber with the lid member interposed between the central recess of the partition member partitioning the main liquid chamber by a lid member. 3. The orifice passage is formed in a circumferential groove that opens to the outer peripheral surface of the member and extends in the circumferential direction, and the orifice passage allows the main liquid chamber and the sub liquid chamber to communicate with each other. Pneumatic vibration type active vibration isolator described in 1.   The fluid chamber is configured to include a main liquid chamber in which a part of the wall is formed by the main rubber elastic body and a pressure change is generated when vibration is input, while a part of the wall is flexible. An equilibrium chamber is formed which is made of a membrane and is allowed to change in volume, in which an incompressible fluid is sealed, and a fluid communication path which allows the equilibrium chamber to communicate with the main liquid chamber. 4. A pneumatic vibration type active vibration isolator according to any one of claims 1 to 3.   The first attachment member is attached to the power unit of the automobile, and the second attachment member is attached to the body of the automobile so that the vibration between the power unit and the body is performed. The two air pressure sources are set to a negative pressure and an atmospheric pressure generated in an intake system of an internal combustion engine of an automobile, and the working air chambers are alternately switched by switching the switching valve with respect to the two air pressure sources. 5. The pneumatic vibration type active vibration isolator according to claim 1, wherein the pneumatic vibration type active vibration isolator is connected.

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