JP2006144885A - Vibration suppressing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vibration suppressing device using a piezoelectric element capable of stably providing a vibration suppressing effect. <P>SOLUTION: This vibration suppressing device V suppresses the vibration of a vibration suppressed object 1 by the piezoelectric element 2 converting the mechanical energy to an electric energy of the vibration suppressed object (transmission case) 1 under vibration and an electric circuit 4 converting an electric energy generated in the piezoelectric element 2 into a heat energy and consuming the heat energy. The vibration suppressing device comprises a cover member (cover) 3 covering and holding the piezoelectric element 2 and fixedly holding the piezoelectric element in the clearance thereof from the vibration suppressed object 1 and a fluid (grease) 6 filled between the piezoelectric element 2 and the vibration suppressed object 1 and between the piezoelectric element 2 and the cover member 3. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an apparatus for suppressing vibration using a piezoelectric element, and more particularly to a passive type vibration suppressing apparatus.

  A piezoelectric element generates an electromotive force according to an applied load. Therefore, if the electric power is consumed as heat, the mechanical energy is absorbed as thermal energy, and the vibration is absorbed by the piezoelectric element and the electric circuit. Or can be suppressed. One example thereof is described in Patent Document 1. The device described in Patent Document 1 holds a piezoelectric element from a direction of its operating axis by a pair of connecting members having a larger elastic modulus than that of the piezoelectric element, and a fastening member such as a bolt is provided in a through hole provided in the connecting member. The piezoelectric element is configured to be inserted and fixed to the object to be controlled, and in that state, the piezoelectric element is connected to an external circuit. Therefore, according to such a structure, the deformation or movement of the vibration control object can be transmitted to the piezoelectric element through the connection member having a large elastic modulus, and as a result, vibration energy, that is, mechanical energy can be converted into electric energy. It is said that.

In connection with the technology for absorbing or suppressing vibration, Patent Document 2 discloses that a fluid film is formed between a bearing that supports a rotating shaft and a fixed surface, and the bearing is supported by the fluid film pressure. A squeeze film damper bearing that reduces vibration of a high-speed rotating shaft such as a centrifugal compressor by utilizing a so-called fluid squeeze action is described.
JP 2000-357824 A JP-A-8-261231

  In the vibration damping device using a piezoelectric element described in Patent Document 1, a connecting member having a larger elastic modulus than that of the piezoelectric element is disposed at both ends in the operation axis direction of the piezoelectric element, and screw holes processed into the connecting member are provided. The piezoelectric element is fixed to the damping object by screwing the connecting member to the damping object with a countersunk screw. However, the contact state (for example, contact area and contact surface pressure) between the piezoelectric element and the connecting member changes due to variations in the dimensional accuracy of the piezoelectric element or countersunk screw or the processing accuracy of the screw hole, and as a result, desired vibration suppression The effect may not be obtained stably.

  Therefore, the piezoelectric element is fixed to the object to be controlled by a cover provided with a space for accommodating the piezoelectric element, that is, the piezoelectric element is accommodated in the space provided on the inner surface of the cover, and the cover is fastened with bolts, for example. It can be considered that the piezoelectric element is fixed to the vibration suppression object in a state where the piezoelectric element is in contact with the cover and the vibration suppression object by fixing the vibration element to the vibration suppression object by the above method. However, in that case, the surface of the piezoelectric element may be damaged by minute friction between the piezoelectric element, the cover, and the vibration control object generated when the vibration control object vibrates. For example, when the electrode on the surface of the piezoelectric element is damaged, the damaged portion does not function as a piezoelectric element, and the vibration suppressing effect by the piezoelectric element is reduced. Eventually, in this case as well, there is a possibility that the desired vibration suppressing effect cannot be obtained stably.

  The present invention has been made paying attention to the above technical problem, and an object of the present invention is to provide a vibration suppressing device using a piezoelectric element capable of stably obtaining a vibration suppressing effect.

  In order to achieve the above-mentioned object, the invention of claim 1 includes a piezoelectric element that converts mechanical energy of a vibration-damping object into electrical energy, and electrical energy generated by the piezoelectric element is converted into thermal energy. In a vibration suppressing device that suppresses vibration of the vibration suppression object by a consumed electric circuit, a lid member that covers and holds the piezoelectric element and is fixed between the vibration suppression object and the piezoelectric element And the damping object, and a fluid filled between the piezoelectric element and the lid member.

  According to a second aspect of the present invention, in the first aspect of the present invention, there is provided a storage portion for storing the fluid between the piezoelectric element and the damping object and between the piezoelectric element and the lid member. It is an apparatus characterized by being provided.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the object to be damped and the lid member are respectively formed of materials having the same linear expansion coefficient. It is a device.

  According to the first aspect of the present invention, when the object to be controlled vibrates, a repetitive load due to the vibration acts on the piezoelectric element, and an electromotive force based on the load is generated, and a current flows in the electric circuit. In the electric circuit, the current is converted into heat and consumed. That is, mechanical energy (vibration energy or strain energy) due to vibration is changed into thermal energy and consumed, and as a result, mechanical energy is reduced and vibration is suppressed. At this time, friction is generated between the surface of the piezoelectric element and the object to be damped and the lid member when a repeated load due to vibration is applied, but between the piezoelectric element and the object to be damped, and between the piezoelectric element and the lid. The lubrication action of the fluid filled between the members relaxes the friction between them and prevents or suppresses the surface of the piezoelectric element from being damaged by the friction. Therefore, it can be avoided or suppressed that the surface of the piezoelectric element, for example, an electrode provided on the surface is damaged and the vibration suppressing effect by the piezoelectric element is reduced. As a result, the vibration suppressing effect by the piezoelectric element can be stably obtained.

  In addition, since fluid is filled between the piezoelectric element and the object to be damped and between the piezoelectric element and the lid member, a load in the compression direction or shear direction due to vibration acts between them. The so-called fluid squeeze action provides damping performance against the vibration. Therefore, the vibration suppression effect by the squeeze action can be obtained together with the vibration suppression effect by the piezoelectric element, and the vibration suppression performance as the vibration suppression device can be improved.

  Further, according to the second aspect of the present invention, there is provided a reservoir for storing the fluid filled between the piezoelectric element and the vibration damping object and between the piezoelectric element, so that the fluid is Prevents or suppresses exhaustion and exhaustion from all the gaps between the piezoelectric element, the vibration control object and the lid member, lubrication effect by the fluid, and fluid squeeze action between them The vibration damping effect due to can be maintained.

  According to the invention of claim 3, the vibration damping object and the lid member are respectively formed of materials having the same linear expansion coefficient, so that the piezoelectric element and the vibration damping object are changed by temperature change. It can be avoided or suppressed that the contact state with the object or the contact state between the piezoelectric element and the lid member changes and the vibration suppressing effect by the piezoelectric element is lowered. As a result, the vibration suppressing effect by the piezoelectric element can be stably obtained.

  The present invention will be described based on specific examples. FIG. 1 is a schematic diagram for explaining a first configuration example of a vibration suppression device V according to the present invention, and shows a state in which the vibration suppression device V is installed on a vibration control object 1. Further, in the first configuration example, an example is shown in which the vibration suppression target 1 is a transmission case 1 mounted on a vehicle, for example.

  In FIG. 1, the piezoelectric element 2 is fixed to a predetermined vibration suppression target portion of the transmission case 1 by a cover 3. Here, the piezoelectric element 2 is a member that converts mechanical energy such as vibration energy or strain energy into electric energy, generates dielectric polarization according to stress, and generates electromotive force. And it is formed from ceramics, such as barium titanate and PZT, for example like the conventional one. The piezoelectric element 2 has a flat plate shape, for example, and is formed so that the polarization direction is the thickness direction of the flat plate shape (vertical direction in FIG. 1). On both end faces 2a and 2b in the polarization direction, electrodes 2p and 2n formed by applying, for example, conductive metal paste are provided.

  The piezoelectric element 2 is connected to an electric circuit 4 for converting the electric energy generated in the piezoelectric element 2 into heat and consuming it. The electric circuit 4 includes, for example, a resistor and a coil (both not shown) connected in series, and is electrically connected to the electrodes 2p and 2n of the piezoelectric element 2 via, for example, lead wires 4p and 4n, respectively. It is connected to the.

  The cover 3 is a cover member that covers and holds the piezoelectric element 2 and is sandwiched and fixed between the cover 3 and the same material as the material that forms the transmission case 1, or a material that forms the transmission case 1. And a material having the same linear expansion coefficient. That is, the cover 3 is formed with a recess 3a for covering and holding the piezoelectric element 2 on the inner surface thereof, that is, the surface (the lower surface in FIG. 1) facing the transmission case 1 of the cover 3, The piezoelectric element 2 is held in the recess 3a and is fastened to the transmission case 1 by being fastened with a bolt 5 in a direction perpendicular to the surface of the transmission case 1, for example.

  At this time, the depth of the recess 3a (that is, the length in the vertical direction in FIG. 1) is set to an appropriate predetermined dimension in consideration of the thickness of the piezoelectric element 2, that is, the length of the piezoelectric element 2 in the polarization direction. That is, when the cover 3 is fixed to the transmission case 1 with the piezoelectric element 2 held in the recess 3a, the cover 3 is bolted in the direction perpendicular to the surface of the transmission case 1 as described above. A state in which the piezoelectric element 2 and the transmission case 1 and between the piezoelectric element 2 and the cover 3 are brought into contact with each other with an appropriate surface pressure, and an appropriate compressive stress is generated in the piezoelectric element 2 in the polarization direction. Thus, the piezoelectric element 2 can be fixed to the transmission case 1. Therefore, vibration generated in the transmission case 1 can be efficiently transmitted to the piezoelectric element 2, and as a result, vibration of the transmission case 1 can be effectively reduced or suppressed.

  Further, when the ambient temperature around the vibration suppressing device V or the temperature of the vibration suppressing device V itself changes, the transmission case 1 and the cover 3 expand or contract, and the contact state between the piezoelectric element 2 and the transmission case 1 or the piezoelectricity. There is a possibility that the contact state between the element 2 and the cover 3 changes, for example, a gap is formed in the contact portion between the piezoelectric element 2 and the transmission case 1 or the cover 3, and the vibration suppression effect by the piezoelectric element 2 is reduced. There is. Therefore, in the vibration suppression device V according to the present invention, as described above, the transmission case 1 and the cover 3 are each formed of the same material or a material having the same linear expansion coefficient. It is possible to avoid or suppress the fluctuation of the vibration suppressing effect by the piezoelectric element 2 due to the temperature change. As a result, the vibration suppressing effect by the piezoelectric element 2 can be stably obtained.

  As described above, when the piezoelectric element 2 is fixed in a state of being sandwiched between the transmission case 1 and the cover 3 by the cover 3, the piezoelectric element 2 and the transmission case 1 and between the piezoelectric element 2 and the cover are covered. 3 is filled with a predetermined fluid 6 and enclosed. Here, the predetermined fluid 6 has an appropriate viscosity capable of staying without flowing out between the piezoelectric element 2 and the transmission case 1 and between the piezoelectric element 2 and the cover 3, and is appropriate. In this specific example, an example in which grease 6 for lubricating machine parts is used as the fluid 6 is shown.

  Although not particularly illustrated, a space defined by the recess 3a and the transmission case 1 is a fluid such as grease 6 around the recess 3a at the contact portion when the cover 3 is fixed to the transmission case 1. It is sealed by a predetermined method so as to have a sealing property. Although not particularly shown, when the electric circuit 4 is installed outside the cover 3, that is, at a place other than the inside of the recess 3a, a predetermined method is similarly applied to a portion where the lead wires 2p and 2n are drawn from the recess 3a. It is sealed by.

  Next, an operation in the first configuration example of the vibration suppressing device V will be described. When vibration occurs in the transmission case 1, a repeated load due to the vibration acts on the piezoelectric element 2, and the piezoelectric element 2 generates an electromotive force based on the load. Then, a current due to the electromotive force flows through the electric circuit 4 connected to the electrodes 2p and 2n of the piezoelectric element 2, and mainly generates Joule heat by the resistance and is consumed as heat. That is, mechanical energy (vibration energy or distortion energy) due to vibration generated in the transmission case 1 is consumed by being converted into thermal energy, and as a result, mechanical energy is reduced and vibration is suppressed.

  When vibration occurs in the transmission case 1 in this way, the surface of the piezoelectric element 2 that is in contact with the transmission case 1 and the cover 3, that is, both end faces 2 a and 2 b in the polarization direction of the piezoelectric element 2 in this first configuration example. When the electrode 2p, 2n provided in each is subjected to a repeated load due to vibration, friction occurs between the surfaces of the transmission case 1 and the cover 3 facing the electrodes 2p, 2n. At this time, as described above, since the grease 6 is filled and sealed between the piezoelectric element 2 and the transmission case 1 and between the piezoelectric element 2 and the cover 3, the lubricating action of the grease 6 is achieved. Thus, friction generated between them is relieved, and the electrodes 2p and 2n are prevented or suppressed from being damaged by friction. Therefore, it can avoid or suppress that each electrode 2p, 2n of the piezoelectric element 2 is damaged and the vibration suppressing effect by the piezoelectric element 2 is reduced, and the vibration suppressing effect by the piezoelectric element 2 can be stably obtained. Can do.

  Further, as described above, the grease 6 is filled between the piezoelectric element 2 and the transmission case 1 and between the piezoelectric element 2 and the cover 3, so that a compression direction or a shearing direction due to vibrations therebetween. When the above stress is generated, it is possible to obtain a damping performance against vibration due to a so-called fluid squeeze action.

  Here, the squeeze action of the fluid will be briefly described. FIG. 3 is a schematic diagram for explaining the outline of the squeeze action. FIG. 3A shows a state in which no vibration is generated in the transmission case 1, and FIG. Shows a state where vibration occurs.

  FIG. 3 shows the state in which the surface of the transmission case 1 is in contact with the surface of the piezoelectric element 2, more specifically, the surface of the electrode 2n, by enlarging the cross section in the direction perpendicular to the contact surface C. The space 6 defined by the surface of the transmission case 1 and the surface of the electrode 2n of the piezoelectric element 2 facing each other and contacting the surface of the electrode 2n is filled or sealed with grease 6. It shows the state being done.

  When vibration is generated in the transmission case 1 from the state where the transmission case 1 is not vibrated, that is, the state shown in FIG. 3A, a repeated load is applied due to the vibration, as shown in FIG. Moreover, loads Fv and Fh in the direction perpendicular to the contact surface C and in the shear direction act on the contact surface C between the transmission case 1 and the electrode 2n of the piezoelectric element 2. Therefore, on the contact surface C, for example, the vertical load Fv in the direction indicated by the arrow Fv (downward in FIG. 3B) acts, and the direction indicated by the arrow Fh (leftward in FIG. 3B). The transmission case 1 moves relative to the piezoelectric element 2 in the direction indicated by the arrow Fh. That is, a minute slip occurs on the contact surface C.

  At this time, in the portion indicated by the range A in FIG. 3B, the volume of the space defined by minute irregularities on the surfaces of the transmission case 1 and the electrode 2n of the piezoelectric element 2 in the portion is the state before vibration occurs. (Ie, the state shown in FIG. 3A). Then, as the volume decreases, the grease 6 filled and sealed in the portion flows out (squeezed out) from a so-called throttle portion as shown by a range B in FIG. In that case, a frictional resistance is generated between the grease 6 squeezed out from the throttle portion and the throttle portion. Therefore, mechanical energy due to vibration is consumed as frictional resistance, and mechanical energy, that is, vibration is reduced.

  As described above, the volume of the space in which the fluid is encapsulated changes due to the shear force and vertical load acting on the contact surface of the fluid encapsulated in the minute irregularities on the contact surface between the two objects, A so-called squeeze action is an action in which a fluid is squeezed out from an orifice-like gap on the contact surface and frictional resistance is generated at that time, thereby obtaining a damping property against vibration.

  As described above, when the vibration suppressing device V is configured as in the first configuration example described above, when vibration occurs in the transmission case 1, mechanical energy (vibration energy or strain energy) due to the vibration is generated. Then, the electric energy is converted from the piezoelectric element 2, and the current due to the electric energy flows through the electric circuit 4 and is consumed as heat. Eventually, mechanical energy due to vibration generated in the transmission case 1 is consumed as heat after being converted into electric energy, and as a result, vibration of the transmission case 1 can be suppressed or attenuated.

  Further, friction is generated between the surface of the piezoelectric element 2, that is, the surfaces of the electrodes 2p and 2n, and the transmission case 1 and the cover 3 when a repeated load is applied by vibration. Due to the lubricating action of the grease 6 filled and sealed between the piezoelectric element 2 and the cover 3, the friction between them is relieved, and the electrodes 2 p and 2 n of the piezoelectric element 2 may be damaged by the friction. Prevented or suppressed. Therefore, it can be avoided or suppressed that the electrodes 2p and 2n of the piezoelectric element 2 are damaged and the vibration suppressing effect by the piezoelectric element 2 is reduced, and the vibration suppressing effect by the piezoelectric element 2 can be stably obtained. it can.

  Further, as described above, since the grease 6 is filled and sealed between the piezoelectric element 2 and the transmission case 1 and between the piezoelectric element 2 and the cover 3, a vibration damping effect due to a so-called squeeze action is provided. The vibration suppression performance as the vibration suppression device V can be improved.

  As described above, the transmission case 1 and the cover 3 are formed of the same material or materials having the same linear expansion coefficient, so that the vibration caused by the piezoelectric element 2 accompanying a temperature change. The fluctuation of the suppression effect can be avoided or suppressed, and the vibration suppression effect by the piezoelectric element 2 can be stably obtained.

  FIG. 2 is a schematic diagram for explaining a second configuration example of the vibration suppression device V according to the present invention. In FIG. 2A, the vibration suppression device V is controlled as in the case of FIG. The state which is installed in the shaking object 1, ie, the transmission case 1, is shown. FIG. 2B is a view of the concave portion 3a of the cover 3 in the second configuration example as viewed from the front (that is, from the lower side in FIG. 2A), and FIG. It is the figure which looked at the surface of the predetermined | prescribed vibration suppression object location of the transmission case 1 in a 2nd structural example from the front (namely, from the upper side in Fig.2 (a)).

  The second configuration example shown in FIG. 2 stores grease 6 in a predetermined vibration suppression target portion of the transmission case 1 and the recess 3a of the cover 3 as compared with the first configuration example shown in FIG. In this example, dimples 7 are provided, and the same parts as those shown in FIG. 1 are denoted by the same reference numerals as those shown in FIG.

  2A, a large number of dimples 7 are formed on the surface of the recess 3a of the cover 3 (the lower surface in FIG. 2A) as shown in FIG. 2B. Similarly, a large number of dimples 7 are formed on the surface of the predetermined vibration suppression target portion of the transmission case 1 (the upper surface in FIG. 2A) as shown in FIG. Yes.

  The dimple 7 is a hollow having a shape obtained by hollowing out the surface of the concave portion 3 a of the cover 3 and the surface of a predetermined vibration suppression portion of the transmission case 1, and the piezoelectric element 2 is sandwiched between the cover 3 and the transmission case 1. When the grease 6 is filled between the piezoelectric element 2 and the transmission case 1 and between the piezoelectric element 2 and the cover 3, the grease 6 is stored in the recessed portion. Is formed. That is, the dimple 7 functions as a storage portion that stores the grease 6 between the piezoelectric element 2 and the transmission case 1 and between the piezoelectric element 2 and the cover 3.

  The dimples 7 are arranged almost evenly in the range of the portion of the surface of the concave portion 3a of the cover 3 and the surface of the predetermined vibration suppression target portion of the transmission case 1 facing the piezoelectric element 2, for example, They are set to be equally spaced from each other.

  The size of the depression of the dimple 7, that is, the volume of the portion storing the grease 6 of the dimple 7 is, for example, the usage environment, the vibration mode, the shape of the portion, or the part at a predetermined vibration suppression target portion of the transmission case 1. It is set to a predetermined size in consideration of the lifetime.

  Therefore, as described above, the dimples 7 that store the grease 6 are provided between the piezoelectric element 2 and the transmission case 1 and between the piezoelectric element 2 and the cover 3. 6 can be prevented or suppressed from being depleted. For example, as described above in the description of the squeeze action according to FIG. 3, when a minute slip occurs on the contact surface C between the piezoelectric element 2 and the transmission case 1 (or the cover 3) due to vibration, for example, FIG. ), The grease 6 stored in the dimple 7 is newly supplied to the piezoelectric element 2 and the transmission even if the grease 6 flows out to the portion other than the contact surface C from the narrow gap as shown by the range B in FIG. In the contact surface C between the case 1 and between the piezoelectric element 2 and the cover 3, it is prevented or suppressed that all the grease 6 flows out and is exhausted. Therefore, the lubrication effect by the grease 6 on the friction between the piezoelectric element 2 and the transmission case 1 and the cover 3 and the vibration damping effect by the squeeze action of the grease 6 between them can be maintained.

  As described above, the vibration suppression device V is configured as in the above-described second configuration example, so that the vibration suppression effect by the piezoelectric element 2 and the grease 6 are reduced as in the case of the first configuration example described above. The lubrication effect due to the vibration and the vibration damping effect due to the squeeze action of the grease 6 can be obtained together, the vibration suppression performance as the vibration suppression device V can be improved, and between the piezoelectric element 2 and the transmission case 1 In addition, it is possible to prevent or suppress the exhaustion of the grease 6 between the piezoelectric element 2 and the cover 3, and to maintain the lubrication effect and the vibration damping effect by the grease 6.

  The present invention is not limited to the specific examples described above. For example, the shape of the piezoelectric element 2 may be, for example, a disc shape other than the rectangular flat plate shape, and in consideration of the shape of the vibration suppression target portion, the form of vibration, manufacturing restrictions, etc. An appropriate predetermined shape can be obtained. Along with this, the shape of the cover 3 can also be an appropriate predetermined shape.

  In the above-described specific example, the fluid filled between the piezoelectric element 2 and the transmission case 1 that is the object to be damped, and between the piezoelectric element 2 and the cover 3 that is the lid member is used for lubricating the mechanical parts. However, the present invention is not limited to this, and other fluids such as wax may be used.

  Furthermore, in the specific example mentioned above, although the example in which the dimple 7 was provided as a storage part which stores the fluid, ie, grease 6, is shown, the shape of the storage part is not limited to this. A large number of grooves for storage can be arranged in parallel or in a lattice shape, or any shape taking into account the shape of the vibration suppression target portion, the form of vibration, and the like.

  And the damping object in this invention is not limited to the transmission case 1 mentioned above, All the members and structures which can install the vibration suppression apparatus V in this invention of the structure mentioned above in a damping object location Etc. can be targeted.

It is a figure which shows typically the 1st structural example of this invention, Comprising: It is a figure which shows the state by which the vibration suppression apparatus is installed in the damping object. It is a figure which shows the 2nd structural example of this invention typically, Comprising: (a) is a figure which shows the state in which the vibration suppression apparatus is installed in the damping object, (b) is a cover member (C) is the figure which looked at the surface of the predetermined | prescribed damping object location of the damping object from the front. It is a figure for demonstrating the squeeze effect | action of a fluid, Comprising: (a) is a figure which shows the state which has not generated the vibration in the damping object, (b) is the state in which the vibration has occurred in the damping object FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Transmission case (damping object), 2 ... Piezoelectric element, 3 ... Cover (lid member), 4 ... Electric circuit, 6 ... Grease (fluid), 7 ... Dimple (storage part).

Claims (3)

The vibration of the vibration suppression object is suppressed by a piezoelectric element that converts mechanical energy of the vibration suppression object into electric energy and an electric circuit that converts the electric energy generated by the piezoelectric element into heat energy and consumes it. In the vibration suppression device,
A lid member that covers and holds the piezoelectric element and is sandwiched and fixed between the object to be damped;
A vibration suppressing apparatus comprising: a fluid filled between the piezoelectric element and the vibration suppression object and between the piezoelectric element and the lid member.   2. The vibration according to claim 1, wherein a reservoir for storing the fluid is provided between the piezoelectric element and the damping object and between the piezoelectric element and the lid member. Suppression device.   3. The vibration suppressing device according to claim 1, wherein the vibration suppression object and the lid member are each formed of a material having the same linear expansion coefficient. 4.

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