JP2005127443A - Variable damping force - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrain generation of heat and heighten the variable responsiveness of damping force. <P>SOLUTION: A piston 4 with a piston rod 3, the tip side of which is slidably passed through one end of a casing 1, is stored in the casing 1, thereby forming two fluid chambers 5a, 5b partitioned by the piston 4. A passage 7 is formed as a clearance gap between the outer peripheral surface of the piston 4 and the inner wall surface of the casing 1, and the fluid chambers 5a, 5b and the passage 7 are filled with a magnetic fluid 6. A magnetic force generating mechanism 21 formed by integrally fitting a piezoelectric element 22 to a supermagnetostrictive element 23 is provided in the interior of the piston 4, and an external power supply 10 is connected to the piezoelectric element 22 through an electric wire 11. In the case of changing the damping force, an electric current is applied to the piezoelectric element 22 to apply distortion of the supermagnetostrictive element 23 with deformation of the piezoelectric element 22, thereby generating magnetic field. The magnetic field is applied to the magnetic fluid 6 to heighten the viscosity of the magnetic fluid 6, whereby the damping force is increased by heightening the resistance when the magnetic fluid 6 passes through the passage 7. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

The present invention relates to a variable attenuator for changing the viscosity of a magnetic fluid, which is a working medium, among variable attenuators for attenuating shocks, motions, and vibrations generated in various structures and devices. It is.

Attenuator (damper) that attenuates the amplitude of vibration control objects such as various structures and devices by converting the energy of shock, motion and vibration generated in various structures and devices into heat and dissipating it. As one type, there is a variable damping device that can change the damping force.
As one of such variable damping devices, a type using a magnetic fluid (MR fluid) as a working medium is known.

A variable damping device using this type of magnetic fluid has the following configuration, as shown schematically in FIG. 10 as an example of a double rod type. That is, the piston 4 is housed in a long cylinder type casing 1 having a through hole 2 for passing the piston rods 3a and 3b at the axial positions of both ends so as to be reciprocally movable in the axial direction. Two fluid chambers 5 a and 5 b partitioned by the piston 4 are formed at both axial ends in the casing 1. Further, piston rods 3a and 3b, which are slidably passed through the through holes 2 of the casing 1, are fixed to both end faces of the piston 4, and the piston rods 3a and 3b are moved along with the reciprocating movement of the piston 4. The casing 1 can be relatively displaced in the axial direction. Further, a passage 7 for allowing the magnetic fluid 6 serving as a working medium to move between the fluid chambers 5a and 5b while generating a required resistance is provided between the outer peripheral surface of the piston 4 and the casing 1. Each of the fluid chambers 5a is formed by a gap provided between the inner wall surface and the fluid chamber 5a.
, 5b and the passage 7 are filled with a magnetic fluid 6, which is formed by uniformly dispersing magnetic particles such as fine iron powder in a viscous fluid such as silicon oil. Furthermore, the piston 4 has a configuration in which an electromagnetic coil 9 is wound around a piston core 8 made of a soft magnetic material such as carbon steel, and an external power source 10 is connected to the electromagnetic coil 9 with one piston rod 3a. It is connected to the inside of the piston core 8 via an electric wire 11 led to the inside. Therefore, by energizing the electromagnetic coil 9, a magnetic field is generated in the electromagnetic coil 9,
The piston 4 can function as an electromagnet.

When a variable damping device having such a configuration is used, the variable damping device is interposed between a fixed object 12 and a damping object (not shown) that is desired to attenuate shocks, motions, and vibrations of various structures or devices. The outer ends of the piston rods 3a and 3b and the casing 1 are attached to the attenuation object and the fixed side 12, respectively.
When the piston 4 integral with the piston rods 3a and 3b is reciprocated in the casing 1 when the piston 4 is relatively displaced with respect to the fixed side 12 due to vibration, the magnetic fluid is moved when the piston 4 reciprocates. A damping action is performed by the resistance when 6 is moved through the passage 7 between the fluid chambers 5a and 5b.

In the above, when the damping force is changed, the external power source 10 energizes the electromagnetic coil 9 of the piston 4 to generate a magnetic field, the magnetic field generated by the electromagnetic coil 9 is applied to the magnetic fluid 6, and By changing the strength of the magnetic field generated by controlling the magnetomotive force in the electromagnetic coil 9, the magnetic fluid 6 is changed from the viscosity in the initial state where the magnetic field does not act,
The viscosity is increased so as to increase in accordance with the strength of the magnetic field, and the magnetic particles in the magnetic fluid 6 are adsorbed on the outer peripheral surface portion of the piston 4 that is electromagnetized when the electromagnetic coil 9 is energized. Thus, the cross-sectional area of the passage 7 formed between the outer peripheral surface of the piston 4 and the inner wall surface of the casing 1 is reduced. Accordingly, the damping force is increased by increasing the resistance when the magnetic fluid 6 is moved through the passage 7 between the fluid chambers 5a and 5b as the piston 4 reciprocates in the casing 1. It can be raised.

By the way, in recent years, focusing on the inverse magnetostriction effect that changes the internal magnetization by applying stress to a magnetic material magnetized in a magnetic field, as an element that converts voltage into magnetization, an outline is shown in FIGS. As shown, an electromagnetic conversion element for controlling magnetic force has been proposed (see, for example, Non-Patent Document 1). This is because the giant magnetostrictive element 13 and the piezoelectric element (piezo element) 14 are connected to the movable yoke 1.
5 are arranged in series with the magnetic yokes 5 interposed therebetween, and the super magnetostrictive element 13 and the piezoelectric element 14 are sandwiched between the two magnetic yokes 16 and 17 from the outside in the series direction. Tighten with a non-magnetic stainless steel bolt (not shown) so that relative displacement can be constrained in a state where some strain is generated in the giant magnetostrictive element 13, and further, the movable yoke 15 and the magnetic force are arranged in parallel with the giant magnetostrictive element 13. Magnet (permanent magnet) 1 magnetized in the longitudinal direction between the yoke 16
The first magnetic circuit 19 is composed of the giant magnetostrictive element 13 and the magnet 18.
a, and the second magnetic circuit 19b including the magnet 18 and the gap 20 are formed in parallel.

With such a configuration, normally, as shown in FIG. 11A, the magnetostrictive element 13 is magnetized by the magnetomotive force generated by the magnet 18, and the second magnetic circuit 1 including the magnet 18 and the gap 20 is used.
In 9b, an appropriate suction force can be generated. Further, as shown in FIG. 11B, when a positive voltage is applied to the piezoelectric element 14 to cause the piezoelectric element 14 to expand and deform, the giant magnetostrictive element 13 is compressed by the amount of the expansion change. By reducing the distortion, the magnetization of the giant magnetostrictive element 13 can be reduced by the inverse magnetostrictive effect. Accordingly, if the magnetic flux generated from the magnet 18 is constant, the first magnetic circuit 1 including the super magnetostrictive element 13 and the magnet 18 is used.
Since the magnetic flux of 9a is decreased, the magnetic flux of the second magnetic circuit 19b by the magnet 18 and the gap 20 can be increased, and the attractive force acting between the yokes can be increased.
On the other hand, by applying a negative voltage to the piezoelectric element 14 to cause the piezoelectric element 14 to contract and deform,
As the magnetization of the giant magnetostrictive element 13 is increased to increase the magnetization, and the magnetic flux of the first magnetic circuit 19a by the giant magnetostrictive element 13 and the magnet 18 is increased, the magnet 18 is made to correspond to the increase.
Thus, the magnetic flux of the second magnetic circuit 19b due to the gap 20 can be reduced to reduce the attractive force acting between the yokes.

Special table 2001-507434 gazette Ueno, Kaoru, Tani, "Magnetic Magnetostriction / Piezoelectric Magnetic Transformer for Controlling Magnetic Force and its Application to Electrolevation", Transactions of the Japan Society of Mechanical Engineers (C), 2001, 67, 658, p. 1897-1904

However, in the conventional variable damping device as shown in Patent Document 1, it is necessary to energize the electromagnetic coil 9 in order to apply a magnetic field to the magnetic fluid 6 in order to change the damping force. In operation over time, the electromagnetic coil 9 generates heat due to coil resistance, and energy is released to the outside as heat, so that there is a problem that power loss is large. Further, when the temperature of the magnetic fluid 6 rises as the electromagnetic coil 9 generates heat, the property (characteristics) of the magnetic fluid 6 changes, which may cause a reduction in damping force.

Furthermore, for example, in the equipment used under conditions that cannot release heat from the atmosphere, such as vacuum conditions such as outer space or conditions close to vacuum, or equipment used under extremely low temperature conditions, heat generation is disadvantageous. It is difficult to employ a variable attenuation device.

Furthermore, the damping force is variably controlled by changing the current applied to the electromagnetic coil 9, but in this case, the variable response of the damping force becomes worse due to the counter electromotive force generated in the electromagnetic coil 9. That is, there is a problem that the high-frequency response is poor because it has a time constant to form an electric circuit with a coil and has the characteristics of a low-pass filter.

The non-patent document 1 uses the inverse magnetostriction effect generated by applying stress to the giant magnetostrictive element 13 disposed in the magnetic field, so that the magnet 18 is used as the giant magnetostrictive element 13. It is necessary to provide it in parallel. The giant magnetostrictive element 13 is arranged in series via the piezoelectric element 14 and the movable yoke 15 so that a slight distortion is generated in the initial state, that is, a slight magnetic field is generated. The idea of generating a magnetic field to be applied to the magnetic fluid by the giant magnetostrictive element only when it is desired to change the damping force as in the variable damping device of the present invention to be described later is absolutely not. It is not shown and is not even suggested.

Therefore, the present invention can be used for equipment that can suppress heat generation and that is used under conditions that cannot release heat from the atmosphere, such as vacuum conditions such as outer space or conditions that are close to vacuum, or equipment that is used under cryogenic conditions. It is an object of the present invention to provide a variable damping device that can be advantageous and that is responsive to control.

In order to solve the above problems, the present invention slidably accommodates a piston with a piston rod in a casing, forms two fluid chambers partitioned by the piston in the casing, and each of the fluids The chambers communicate with each other through a required passage so that the magnetic fluid filled in each fluid chamber passes through the passage, and further includes a super magnetostrictive element and a piezoelectric element, and the piezoelectric element is deformed when energized. Thus, the magnetic force generation mechanism configured to generate a magnetic field by applying strain to the giant magnetostrictive element is provided in the vicinity of the fluid chamber or in the vicinity of the passage.

In addition, the magnetic force generation mechanism has a giant magnetostrictive element disposed on one end side in the deformation direction when the piezoelectric element is energized, and the piezoelectric element and the giant magnetostrictive element are constrained from both ends, thereby energizing the piezoelectric element. A structure in which a magnetic field can be generated by applying a strain in the compression direction to the giant magnetostrictive element by stretching and deformation.

Further, the magnetic force generation mechanism is configured such that the giant magnetostrictive element is integrally joined to a surface along the deformation direction when the piezoelectric element is energized, and the magnetostrictive element is strained along with the deformation when the piezoelectric element is energized. It is set as the structure which can provide and generate | occur | produce a magnetic field.

Furthermore, the piezoelectric element has a flat plate shape and the giant magnetostrictive element has a flat plate shape, which are stacked and joined together to form a magnetic force generation mechanism.

Furthermore, a rod-shaped super magnetostrictive element is inserted and arranged inside a cylindrical piezoelectric element that deforms in the axial direction when energized, and the inner surface of the piezoelectric element and the outer surface of the super magnetostrictive element are joined together. A rod-shaped piezoelectric element that is deformed in the axial direction when energized is inserted and arranged inside a cylindrical super magnetostrictive element configured to form a magnetic force generation mechanism, and the outer surface of the piezoelectric element and the super The magnetostrictive element is integrally joined to the inner surface to form a magnetic force generation mechanism.

According to the variable damping device of the present invention, the following excellent effects are exhibited.
(1) A piston with a piston rod is slidably accommodated in a casing, two fluid chambers partitioned by the piston are formed in the casing, and the fluid chambers communicate with each other through a required passage. In addition, the magnetic fluid filled in each fluid chamber passes through the passage, and further, the magnetostrictive element is composed of a super magnetostrictive element and a piezoelectric element, and is deformed when the piezoelectric element is energized. Since the magnetic force generating mechanism configured to generate a magnetic field is provided in the vicinity of the fluid chamber or in the vicinity of the passage, the super magnetostrictive element can be obtained by energizing and deforming the piezoelectric element. When the piston is reciprocated in the casing, the magnetic fluid is generated by applying a strain to the magnetic fluid to increase the viscosity of the magnetic fluid. One of it is possible to increase the resistance of the magnetic fluid flows through the passageway in between the fluid chambers, it is possible to change the damping force.
(2) The change in the damping force can be carried out by energizing and deforming the piezoelectric element. Since this piezoelectric element acts as a capacitor element electrically, the direct-current applied voltage for generating a certain strain is applied. On the other hand, since the deformed state can be maintained with the power consumption of the degree of charge retention, when holding the giant magnetostrictive element in a state of applying the required strain and continuing to generate the required magnetic field, almost no power is consumed. The energy efficiency can be greatly increased as compared with a variable attenuation device having a conventional electromagnetic coil.
(3) In addition, since no electromagnetic coil is used, coil heat generation can be prevented, and since there is almost no heat generation from the giant magnetostrictive element and piezoelectric element, the vibration energy of the object to be attenuated is converted into heat. The amount of heat generated can be made substantially equal to the amount of heat generated when dissipated, so that the amount of heat generated can be greatly reduced compared to the variable damping mechanism having the conventional electromagnetic coil described above. The present invention can be advantageously applied to various devices used in an environment where heat cannot be released to the atmosphere such as a space, or devices used in a cryogenic environment.
(4) Since the possibility of heating the magnetic fluid can be suppressed, it is possible to prevent the magnetic fluid from changing its properties and reducing the damping force.
(5) Since the electric circuit can have a circuit configuration without a coil, there is no back electromotive force generated by the coil as in the conventional variable attenuation mechanism, so there is no electrical low-pass filter characteristic and attenuation. The variable response of the force can be fast.
(6) In addition, the magnetic force generation mechanism includes a giant magnetostrictive element disposed on one end side in the deformation direction when the piezoelectric element is energized, and restrains the piezoelectric element and the giant magnetostrictive element from both ends, By adopting a configuration that can generate a magnetic field by applying a strain in the compression direction to the giant magnetostrictive element by stretching deformation during energization, strain is applied to the giant magnetostrictive element by stretching deformation of the piezoelectric element. A magnetic force generating mechanism that can be generated can be easily configured.
(7) Further, the magnetic force generation mechanism is configured such that the giant magnetostrictive element is integrally joined to a surface along a deformation direction when the piezoelectric element is energized, and the giant magnetostrictive element is accompanied by the deformation when the piezoelectric element is energized. By applying a strain to the piezoelectric element and generating a magnetic field, the piezoelectric element and the giant magnetostrictive element are not restricted from the outside, and the piezoelectric element and the giant magnetostrictive element are strained along with expansion and contraction when the piezoelectric element is energized. Thus, a magnetic force generation mechanism that can generate a magnetic field can be easily configured.
(8) Furthermore, the piezoelectric element and the giant magnetostriction are formed by forming the piezoelectric element into a flat plate shape and forming the super magnetostrictive element into a flat plate shape, laminated and integrally bonded to form a magnetic force generation mechanism. A magnetic force generation mechanism formed by joining elements can be easily formed.
(9) A rod-shaped giant magnetostrictive element is inserted and disposed inside a cylindrical piezoelectric element that deforms in the axial direction when energized, and the inner side surface of the piezoelectric element and the outer side surface of the giant magnetostrictive element are joined together. A rod-shaped piezoelectric element that is deformed in the axial direction when energized is inserted and arranged inside a cylindrical super magnetostrictive element configured to form a magnetic force generation mechanism, and the outer surface of the piezoelectric element and the super A magnetic force generating mechanism that can apply uniform strain to the giant magnetostrictive element by deformation of the piezoelectric element by forming a magnetic force generating mechanism by integrally joining the inner surface of the magnetostrictive element. It can be easily configured.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

FIGS. 1A and 1B show a case where the present invention is applied to a single-rod variable attenuation device as an embodiment of the variable attenuation device of the present invention. The piston 4 is accommodated so as to be reciprocally movable in the axial direction, and two fluid chambers 5 a and 5 b partitioned by the piston 4 are formed in the casing 1. A piston rod 3 having a base end fixed integrally on one side of the piston 4 is slidably inserted through the through-hole 2 and protrudes to the outside of the casing 1. The rod 3 moves in the longitudinal direction together with the piston 4. It can be so.
Further, a gap having a required interval to be a passage 7 for the magnetic fluid 6 is formed between the outer peripheral surface of the piston 4 and the inner wall surface of the casing 1, and the two fluid chambers 5 a and 5 b and the passage 7 are connected to each other in FIG. A magnetic fluid 6 similar to that shown in FIG. Furthermore, the axial center portion of the piston 4 has a hollow structure, and a magnetic force (magnetic field) generating mechanism 21 composed of the piezoelectric element 22 and the giant magnetostrictive element 23 is provided therein, and the piezoelectric element 22 of the magnetic force generating mechanism 21 is provided in the piezoelectric element 22. An external power source 10 (see FIG. 10) is connected via an electric wire 11 disposed through the inside of the piston rod 3.

The magnetic force generation mechanism 21 is configured such that the direction in which the piezoelectric element 22 expands or contracts when energized and the direction in which the giant magnetostrictive element 23 should be distorted to generate a magnetic field are aligned in the same direction. 22 and a giant magnetostrictive element 23 are provided in a series arrangement or a parallel arrangement so that the giant magnetostrictive element 23 can be distorted by deformation when the piezoelectric element 22 is energized. With this configuration, when the piston 4 is moved in the casing 1 by the giant magnetostrictive element 23 to which strain is applied in accordance with the deformation of the piezoelectric element 22, the passage 7.
It is possible to generate a magnetic field for acting on the magnetic fluid 6 through which the liquid is circulated.

A specific configuration of the magnetic force generation mechanism 21 will be described. FIG. 1B shows an example of a type in which the piezoelectric element 22 and the giant magnetostrictive element 23 are arranged in parallel. That is, two plate-like piezoelectric elements which are extended or contracted in the longitudinal direction by energization on both sides of a plate-like giant magnetostrictive element 23 capable of generating a magnetic field by applying strain in the longitudinal direction. The element 22 is arranged, and the piezoelectric elements 22 are integrally bonded and fixed to both surfaces of the giant magnetostrictive element 23 with an epoxy adhesive or the like. With such a configuration, each of the piezoelectric elements 2 described above is used.
2 is energized, and the piezoelectric elements 22 are extended or contracted in the longitudinal direction in synchronization with each other. The magnetic field can be generated by applying a strain that causes contraction.

The piezoelectric element 22 can freely set the energization direction and the direction of expansion or contraction with the energization in the same direction or orthogonal directions by appropriately adjusting the crystal orientation. For this reason, when the flat plate-shaped piezoelectric element 22 is elongated or contracted in the longitudinal direction in the above, if it is necessary to energize the flat plate-shaped piezoelectric element 22 in the thickness direction, FIG. As shown in FIG. 4B, a wrap-around electrode 24 is integrally attached to each piezoelectric element 22 so that a part of the electrode wraps around to the anti-joint surface side with the giant magnetostrictive element 23 on the joint face side with the giant magnetostrictive element 23. Thus, a joint is integrally fixed to the giant magnetostrictive element 23 via the wraparound electrode 24, and the surface of the piezoelectric element 22 on the side of the anti-supermagnetostrictive element 23 and the wraparound electrode 24 wrap around to the side of the antiferromagnetic magnetostrictive element 23. Connect the electric wire 11 to the set electrode part,
The external power supply 10 may be connected.

  Other components that are the same as those shown in FIG.

When using the variable damping device of the present invention having the above-described configuration, a damping object (not shown) that desires damping of impact, motion, and vibration of various structures or devices, and a fixed side (not shown) The casing 1 is arranged between the one end of the casing 1 and the other end of the casing 1 on the fixed side, and the other end of the piston rod 3 is attached to the other end of the target and the fixed side. In this state, when the object to be attenuated is relatively displaced with respect to the fixed side due to impact, motion or vibration, the piston 4 integral with the piston rod 3 is reciprocated in the casing 1, and the piston 4 As the magnetic fluid 6 is reciprocally moved through the passage 7 between the fluid chambers 5a and 5b, a damping action is performed.

In the above, when the external power source 10 energizes the piezoelectric element 22 of the magnetic force generation mechanism 21 via the electric wire 11, the piezoelectric element 22 is deformed in the longitudinal direction with a deformation amount corresponding to the voltage supplied from the external power source 10. It is deformed so as to expand or contract. As a result, the super magnetostrictive element 23 is stretched in the longitudinal direction or strained in the contraction direction with a strength corresponding to the deformation amount of the piezoelectric element 22, so that a magnetic field is generated by the super magnetostrictive element 23. . Since the giant magnetostrictive element 23 of the magnetic force generating mechanism 21 is provided inside the piston 4, it is generated by the giant magnetostrictive element 23 with respect to the magnetic fluid 6 existing around the piston 4. A magnetic field is applied. For this reason, the magnetic fluid 6 is increased in viscosity so as to increase in viscosity according to the strength of the magnetic field from the viscosity in the initial state where no magnetic field is applied, and the magnetic fluid 6 is formed on the outer peripheral surface portion of the piston 4. 6 magnetic particles are adsorbed,
The cross-sectional area of the passage 7 formed by a gap formed between the outer peripheral surface of the piston 4 and the inner wall surface of the casing 1 can be reduced. From this, the resistance when the magnetic fluid 6 is moved through the passage 7 between the fluid chambers 5a and 5b with the reciprocating movement of the piston 4 in the casing 1 is increased, and the damping force is increased. Will be enhanced.

Thus, according to the variable damping mechanism of the present invention, the damping force can be changed by energizing the piezoelectric element 22 of the magnetic force generating mechanism 21. At this time, the piezoelectric element 22 is electrically connected to the capacitor. Since the deformed state can be maintained by supplying electric power of the same level as that of charge retention (to compensate for the charge leakage due to the leakage current of the capacitor), the super magnetostrictive element 23 is held in a state in which the required strain is applied and required. When the magnetic field is continuously generated, power is hardly consumed. Therefore, the energy efficiency can be greatly increased as compared with a variable attenuation device provided with a conventional electromagnetic coil.

In addition, since no electromagnetic coil is used, heat generation from the coil can be prevented, and there is almost no heat generation from the giant magnetostrictive element 23 and the piezoelectric element 22. Therefore, the heat generation from the variable damping device of the present invention is the piston rod 3. The vibration energy of the object to be attenuated that is input from the outside after passing through is almost equal to the calorific value converted into heat, and the calorific value can be greatly reduced compared to the conventional variable attenuation mechanism equipped with the electromagnetic coil. For this reason, it can be advantageously applied to various devices used in an environment where heat cannot be released into the atmosphere such as in a vacuum or outer space, or devices used in a cryogenic environment. Furthermore, the possibility that the magnetic fluid 6 is heated can be suppressed, and the possibility that the damping force is reduced due to the change in the properties of the magnetic fluid 6 can be prevented.

Furthermore, since the electric circuit can be configured without a coil, there is no back electromotive force generated by the coil as in the conventional variable attenuation mechanism, and therefore there is no electrical low-pass filter characteristic, and attenuation. The variable response of the force can be fast.

Next, FIGS. 2 (a), (b), and (c) show another example of the magnetic force generation mechanism 21 of the type in which the piezoelectric element 22 and the giant magnetostrictive element 23 are mounted in parallel as an application example of the above embodiment. It is shown.

That is, the magnetic force generation mechanism 21 shown in FIG. 2 (a) is a plate-like piezoelectric element that is extended or contracted in the longitudinal direction when energized, like the piezoelectric element 22 in the embodiment shown in FIG. 22 is a plate-shaped giant magnetostrictive element 23 that can generate a magnetic field by applying strain to the both sides thereof in the longitudinal or contraction direction along the longitudinal direction.
Are arranged so as to overlap each other, and the superposed surfaces of the respective giant magnetostrictive elements 23 are integrally bonded and fixed to both surfaces of the piezoelectric element 22 by an epoxy adhesive or the like.

Further, the magnetic force generation mechanism 21 shown in FIG. 2 (b) has a cylindrical shape having an inner diameter of a required dimension, and extends inside or contracts in the axial direction when energized. A giant magnetostrictive element 23 having a cylindrical shape having an outer diameter corresponding to the inner diameter of the first electrode and being capable of generating a magnetic field by applying strain in an extending or contracting direction along the axial direction; In addition, the superposed portion of the outer peripheral surface of the giant magnetostrictive element 23 and the inner peripheral surface of the piezoelectric element 22 is integrally joined and fixed with an epoxy adhesive or the like. The magnetic force generation mechanism 21 shown in FIG. 2 (c) has a cylindrical shape having an outer diameter of a required dimension, outside the piezoelectric element 22 that extends or contracts in the axial direction when energized. A giant magnetostrictive element 23 having a cylindrical shape with an inner diameter corresponding to the diameter and configured to generate a magnetic field by applying strain in an extending or contracting direction along the axial direction; and A superposed portion of the inner peripheral surface of the giant magnetostrictive element 23 and the outer peripheral surface of the piezoelectric element 22 is integrally joined and fixed with an epoxy adhesive or the like. Thus, as shown in FIGS. 2B and 2C, the piezoelectric element 22 and the giant magnetostrictive element 23 are arranged concentrically, so that the piezoelectric element 22 is deformed at the time of energization, and the giant magnetostrictive element 23 is evenly strained. It is good also as a structure which enabled it to provide.

Further, the magnetic force generation mechanism 21 shown in FIGS. 3A and 3B shows an example in which the piezoelectric element 22 and the giant magnetostrictive element 23 are arranged in series. The required shape, for example, the required rectangular parallelepiped in FIG. shape,
In FIG. 3B, a magnetic field can be generated by applying a compressive strain to one end side along the direction of expansion and deformation when the piezoelectric element 22 having a cylindrical shape is energized from the direction along the direction of deformation of the piezoelectric element 22. Thus, the giant magnetostrictive element 23 having a shape corresponding to the piezoelectric element 22 is arranged in series, and the pressing plate member 2 is disposed on both ends of the piezoelectric element 22 and the giant magnetostrictive element 23 arranged in series.
5 and the presser plate members 25 are connected to each other via bolts 26 so that the interval between the presser plate members 25 can be kept constant. In such a configuration, the piezoelectric element 2 is energized at a required voltage with the piezoelectric element 22.
2 is deformed so as to extend, and a strain in the compression direction is applied to the super magnetostrictive element 23 by an amount corresponding to the expansion deformation of the piezoelectric element 22, thereby generating a magnetic field by the super magnetostrictive element. It is good also as what made it possible to do.

When the pressing plate members 25 are connected to each other by the bolts 26 in the magnetic force generation mechanism 21 shown in FIGS. 3A and 3B, the piezoelectric elements 22 arranged in series by the pressing plate members 25.
And the giant magnetostrictive element 23 are pressed from both ends so that a precompression force is applied so that the piezoelectric element 22 and the giant magnetostrictive element 23 are not separated. However, in this case, the super magnetostrictive element 23 has a very large compressive stress so that a magnetic field that acts on the magnetic fluid 6 is not generated from the super magnetostrictive element 23 when the piezoelectric element 22 is not energized. Is not working.

Any of the magnetic force generation mechanisms 21 shown in FIGS. 2 (a), (b), and (c) and FIGS.
In this case, strain can be applied to the giant magnetostrictive element 23 by deformation when the piezoelectric element 22 is energized, and a magnetic field for acting on the magnetic fluid 6 can be generated by the giant magnetostrictive element 23.

Next, FIG. 4 shows another embodiment of the present invention. In the same configuration as shown in FIGS. 1 (a) and (b), the passage 7 of the magnetic fluid 6 between the fluid chambers 5a and 5b Instead of forming a gap between the outer peripheral surface of the piston 4 and the inner wall surface of the casing 1, the piston 4
Are provided with one or more orifices 27 penetrating in the axial direction.
The magnetic fluid 6 can be used as a passage between the fluid chambers 5a and 5b.

Other configurations are the same as those shown in FIGS. 1A and 1B, and the same components are denoted by the same reference numerals.

According to the present embodiment, the piezoelectric element 2 is switched by switching off and on the energization of the piezoelectric element 22 of the magnetic force generation mechanism 21 provided in the piston 4 and changing the energization voltage.
2 is applied to the magnetic fluid 6 flowing through the orifice 27 of the piston 4 so that the magnetic fluid 6 flows through the orifice 27.
Since the resistance when passing through can be changed, the damping force can be made variable, and the same effect as that of the embodiment shown in FIGS.

FIG. 5 shows still another embodiment of the present invention. In the same configuration as shown in FIGS. 1A and 1B, the magnetic force generation mechanism 21 is replaced with the piston 4 inside. Thus, it is attached to the outer peripheral portion of the casing 1.

In this case, the magnetic force generation mechanism 21 efficiently generates a magnetic field generated by the giant magnetostrictive element 23 with respect to the passage 7 of the magnetic fluid 6 formed between the outer peripheral surface of the piston 4 and the inner wall surface of the casing 1. In order to be able to act, for example, the piezoelectric element 22, the giant magnetostrictive element 23 and the presser plate members 2 arranged in series in the same manner as the magnetic force generation mechanism 21 shown in FIG.
5 is formed in a ring shape having an inner diameter corresponding to the outer diameter of the casing 1, and each ring-shaped piezoelectric element 22 and the giant magnetostrictive element 23 are arranged in series, and a pressing plate is provided from both ends in the axial direction. A magnetic force generation mechanism 21 formed by restraining deformation in the axial direction by the member 25 is provided on the casing 1.
Are fitted to the outer peripheral surface of the casing 1 via one presser plate member 25, for example.

That is, the giant magnetostrictive element 23 has a ring shape having an inner diameter corresponding to the outer shape of the casing 1 and can generate a magnetic field by applying a compressive stress in the axial direction, and the piezoelectric element 22 has a similar ring shape. In addition, it is assumed that it can be extended and deformed along the axial direction when energized, and is fitted to the outer periphery of the casing 1 on one side of the holding plate member 25 fixed to the outer peripheral surface at the required position in the axial direction of the casing 1. The giant magnetostrictive element 23 and the piezoelectric element 22 are arranged in series, and the other presser plate member 25 is fitted to the outer periphery of the casing 1, and the presser plate member 25 is fixed to the outer peripheral surface of the casing 1. The presser plate member 25 has a bolt 26
By connecting with each other, the positions of both ends of the piezoelectric element 22 and the giant magnetostrictive element 23 arranged in series can be constrained. When the magnetic field generated from the super magnetostrictive element 23 can be applied uniformly to the magnetic fluid 6 and the passage 7 in the casing 1, the super magnetostrictive element 23 is arranged in the axial direction of the casing 1. It is desirable to be located in the middle part.

Other configurations are the same as those shown in FIGS. 1A and 1B, and the same components are denoted by the same reference numerals.

According to the present embodiment, by energizing the piezoelectric element 22 and deforming the piezoelectric element 22 in the expansion direction, the super magnetostrictive element 23 can be strained in the compression direction to generate a magnetic field, and the The magnetic field generated by the giant magnetostrictive element 23 is changed to increase the viscosity of the magnetic fluid 6 by acting on the magnetic fluid 6 in the casing 1 and is generated by the giant magnetostrictive element 23 in the passage 7 portion of the magnetic fluid 6. By applying the applied magnetic field, the area of the passage 7 can be reduced by the adsorption action of the magnetic particles in the magnetic fluid 6 located in the passage 7 portion. From this,
Along with the reciprocating movement of the piston 4 in the casing 1, the resistance when the magnetic fluid 6 passing through the passage 7 passes through the passage 7 can be increased, and the damping force can be made variable. Therefore, also in this embodiment, the same effect as that of the embodiment shown in FIGS.

FIG. 6 shows still another embodiment of the present invention. In the same configuration as shown in FIGS. 1A and 1B, instead of providing the magnetic force generating mechanism 21 inside the piston 4, FIG. The casing 1 is attached to one end on the head side.

In this case, as the magnetic force generation mechanism 21, the super magnetostrictive element 23 for generating a magnetic field can be arranged as close to the magnetic fluid in the casing 1 as possible so that the head side of the casing 1 can be arranged. As shown in FIG. 3 (a), the piezoelectric element 22 and the giant magnetostrictive element 23 arranged in series at the end are restrained by the pressing plate member 25 from both ends, and the giant magnetostrictive element 23 side in the magnetic force generating mechanism 21 is configured. In this configuration, the outer surface of the presser plate member 25 is integrally attached.

Other configurations are the same as those shown in FIGS. 1A and 1B, and the same components are denoted by the same reference numerals.

According to the present embodiment, when the piezoelectric element 22 is energized to deform the piezoelectric element 22 in the expansion direction, the giant magnetostrictive element 23 is compressed and distorted in accordance with the amount of change, and the distorted giant magnetostriction. A magnetic field is generated by the element 23. When the generated magnetic field acts on the magnetic fluid 6 in the casing 1, the viscosity of the magnetic fluid 6 is changed so that the viscosity increases. Therefore, the resistance when the magnetic fluid 6 is caused to flow through the passage 7 with the movement of the piston 4 is increased, whereby the damping force is changed.

Therefore, also in this embodiment, the same effect as that of the embodiment shown in FIGS.

FIG. 7 shows still another embodiment of the present invention. In the same configuration as the embodiment shown in FIGS. 1A and 1B, the passage 7 of the magnetic fluid 6 is connected to the outer peripheral surface of the piston 4. Instead of forming a gap between the casing 1 and the inner wall surface of the casing 1, at both axial end positions of the casing 1,
Both ends of the bypass pipe 28 having a required diameter are connected in communication, and the bypass pipe 28 is connected.
The magnetic fluid 6 which makes fluid chambers 5a and 5b formed on both sides of the piston 4 communicate with each other
Further, a magnetic force generating mechanism 21 is attached to the outer periphery of the intermediate portion of the bypass pipe 28 so that a magnetic field can be efficiently applied to the magnetic fluid 6 flowing in the bypass pipe 28. It is a thing.

As the magnetic force generating mechanism 21, for example, as shown in FIG. 2B, a giant magnetostrictive element 23 that can generate a magnetic field by applying an expansion or contraction strain in the axial direction is arranged on the center side. In addition, a cylindrical piezoelectric element 22 that expands or contracts in the axial direction when energized is fitted to the outer periphery of the outer periphery of the super magnetostrictive element 23 and the piezoelectric element 22.
In the configuration in which the inner peripheral surface of is integrally bonded with an epoxy adhesive or the like,
A through hole 29 having a diameter corresponding to the outer diameter of the bypass pipe 28 is provided in the axial center of the giant magnetostrictive element 23. The through-hole 29 of the giant magnetostrictive element 23 having such a configuration is fitted to the outer periphery of the bypass pipe 28 and fixed to a required portion of the outer peripheral surface of the bypass pipe 28 by a fixing means (not shown). In this configuration, the magnetic force generating mechanism 21 is attached to 28.

Other configurations are the same as those shown in FIGS. 1A and 1B, and the same components are denoted by the same reference numerals.

According to the present embodiment, when the piston 4 is reciprocated in the casing 1 by the vibration to be attenuated input from the outside via the piston rod 3, the magnetism between the fluid chambers 5a and 5b on both sides of the piston 4 is determined. The fluid 6 is moved through the bypass pipe 28, and a damping effect is exhibited by the resistance when the magnetic fluid 6 flows through the bypass pipe 28.

In this state, when the piezoelectric element 22 of the magnetic force generation mechanism 21 is energized from the external power source 10, the piezoelectric element 22 is expanded or contracted in the axial direction in accordance with the energized voltage. Since the giant magnetostrictive element 23 is distorted so as to expand or contract in the axial direction, a magnetic field is generated by the giant magnetostrictive element 23. Since the super magnetostrictive element 23 is disposed on the outer periphery of the bypass pipe 28, the magnetic field generated by the super magnetostrictive element 23 is efficiently applied to the magnetic fluid 6 in the bypass pipe 28, and the magnetic Fluid 6
Since the viscosity of the bypass pipe 28 can be narrowed by adhering the magnetic particles in the magnetic fluid 6 to the inner surface of the bypass pipe 28, the viscosity can be reduced. 6 can increase the resistance when flowing through the bypass pipe 28, and can thereby be changed so as to increase the damping force.

Therefore, the present embodiment can provide the same effects as those of the embodiment shown in FIGS.

FIG. 8 shows a block diagram of a feedback control system based on the amount of strain of the giant magnetostrictive element 23 as an example of a control system used for controlling the damping force by the variable damping device of the present invention. It is as.

That is, for example, as shown in FIG. 2A, the piezoelectric element 22 of the magnetic force generation mechanism 21 in which the piezoelectric element 22 and the giant magnetostrictive element 23 are arranged in parallel and integrated, The element driving amplifier 10a is connected via the electric wire 11, and the control circuit 30 is connected to the piezoelectric element driving amplifier 10a.

The control circuit 30 previously stores and stores data on the correlation between the strain amount of the giant magnetostrictive element 23 and the damping force in the variable damping device of the present invention, and the damping force command value 31 is given. When this is done, the amount of strain to be applied to the giant magnetostrictive element 23 is calculated according to the command signal 33 input from the amplifier 32 based on the command value 31, and the deformation corresponding to the amount of strain of the giant magnetostrictive element 23 is calculated. The voltage required for deforming the piezoelectric element 22 so as to be an amount is output from the piezoelectric element drive amplifier 10a to the piezoelectric element 22.

Further, a strain gauge 34 is attached to a required position of the giant magnetostrictive element 23, and the strain gauge 3
4, a strain amount detection signal of the giant magnetostrictive element 23 can be output to the control circuit 30 as a correction signal 36.

When a damping force command value 31 is given in a control block configured as described above, a command signal 33 corresponding to the command value 31 is input from the amplifier 32 to the control circuit 30. The control circuit 30 calculates the strain amount of the giant magnetostrictive element 23 when a damping force corresponding to the input command signal 33 is obtained, and the deformation amount corresponds to the calculated value of the strain amount. Piezoelectric element 22
The voltage required for deforming is calculated, and the command of the calculated voltage value is output to the piezoelectric element driving amplifier 10a. Thereafter, the piezoelectric element driving amplifier 10a is connected to the control circuit 30.
The piezoelectric element 22 is energized so as to have a desired voltage based on a command from As a result, the piezoelectric element 22 is deformed according to the energized voltage, and with the deformation of the piezoelectric element 22, the giant magnetostrictive element 23 attached thereto is distorted, and according to the amount of distortion. Since the magnetic field is generated, the viscosity of the magnetic fluid 6 in the casing 1 increases according to the strength of the magnetic field generated by the giant magnetostrictive element 23, thereby changing the damping force of the variable damping device of the present invention. .

At this time, if the strain amount of the giant magnetostrictive element 23 detected by the strain gauge 34 is different from the strain amount calculated based on the damping force command value 31 by the control circuit 30, the dynamic strain amplifier Based on the correction signal 36 input from 35, the strain value of the giant magnetostrictive element 23 detected by the strain gauge 34 is calculated by the control circuit 30 based on the damping force command value 31. The command value of the voltage value output from the control circuit 30 to the piezoelectric element driving amplifier 10a may be corrected so as to coincide with the value of.

Further, FIG. 9 shows another example of the control system used for controlling the damping force by the variable damping device of the present invention, in which feedback control based on the strength of the magnetic force generated from the giant magnetostrictive element 23 is performed. The block diagram of the control system for enabling it to do is shown.

In this case, in the same configuration as shown in FIG. 8, the control circuit uses the correlation data between the strain amount of the giant magnetostrictive element 23 and the strength of the generated magnetic field, and the strength of the magnetic field generated by the giant magnetostrictive element 23. The variable damping device of the present invention has a function of storing and storing data of correlation with damping force in advance, and an amplifier 32 based on the command value 31 when the damping force command value 31 is given. In accordance with the command signal 33 inputted from the above, the strength of the magnetic field to be generated by the giant magnetostrictive element 23 and the amount of strain to be given to the giant magnetostrictive element 23 in order to generate the magnetic field having the strength are calculated. The voltage required to deform the piezoelectric element 22 so as to have a deformation amount corresponding to the strain amount to be applied to the giant magnetostrictive element 23 is output from the piezoelectric element drive amplifier 10a to the piezoelectric element 22. There as a control circuit 30a having the ability.

Further, a magnetometer 37 for measuring the strength of the magnetic field generated by the super magnetostrictive element 23 is provided in the vicinity of the super magnetostrictive element 23, and the magnetometer 37 generates the magnetometer 37 with the magnetometer 37. The measured value of the magnetic field strength can be output as the correction signal 36 to the control circuit 30a.

In a control block configured as described above, when a command value 31 of damping force is given, a command signal 33 corresponding to the command value 31 is input from the amplifier 32 to the control circuit 30a. Control circuit 30
a is required to generate the magnetic field strength to be generated by the giant magnetostrictive element 23 when a damping force corresponding to the input command signal 33 is obtained, and to generate a magnetic field of the strength. A strain amount of the giant magnetostrictive element 23 is calculated, a voltage necessary for deforming the piezoelectric element 22 so as to have a deformation amount corresponding to the calculated value of the strain amount is calculated, and a command for the calculated voltage value is calculated. The
Output to the piezoelectric element driving amplifier 10a. Thereafter, the piezoelectric element driving amplifier 10a energizes the piezoelectric element 22 so as to obtain a desired voltage based on a command from the control circuit 30a. As a result, the piezoelectric element 22 is deformed according to the energized voltage, and with the deformation of the piezoelectric element 22, the integrally attached giant magnetostrictive element 23 is distorted, and according to the amount of distortion. Therefore, the viscosity of the magnetic fluid 6 in the casing 1 is increased according to the strength of the magnetic field generated by the giant magnetostrictive element 23, and the damping force of the variable damping device of the present invention is changed. It is done.

At this time, the intensity of the magnetic field generated by the giant magnetostrictive element 23 measured by the magnetometer 37 is generated by the giant magnetostrictive element 23 calculated based on the damping force command value 31 by the control circuit 30a. When the power is different from the strength of the power magnetic field, the correction signal 36 input from the magnetometer 37.
Based on the above, the value of the strength of the magnetic field generated from the giant magnetostrictive element 23 measured by the magnetometer 37 is generated in the giant magnetostrictive element 23 calculated based on the damping force command value 31 by the control circuit 30a. The command value of the voltage value output from the control circuit 30a to the piezoelectric element driving amplifier 10a may be corrected so as to coincide with the value of the magnetic field intensity to be generated.

It should be noted that the present invention is not limited to the above embodiment, and the magnetic force generation mechanism 21 in the embodiment of FIG. 4 is shown in FIGS. 2 (A) (B) (C) and FIG. A magnetic force generation mechanism 21 of the type shown in FIG. Further, if the super magnetostrictive element 23 is distorted in accordance with the deformation of the piezoelectric element 22 so that a magnetic field to be applied to the magnetic fluid 6 by the super magnetostrictive element 23 can be generated, the piezoelectric element 22 and The shape of the giant magnetostrictive element 23, the bonding method between the piezoelectric element 22 and the giant magnetostrictive element 23, and the like may be freely determined according to the shape and arrangement of the attachment location. In each of the above embodiments, the description has been made as a single rod type variable damping device. However, piston rods are attached to both surfaces of the piston 4 so that the tip side slidably penetrates the end of the casing 1 and protrudes to the outside. Needless to say, the present invention can be applied to the double rod type variable damping device and various modifications can be made without departing from the scope of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS One Embodiment of the variable damping device of this invention is shown, (A) is a schematic cut | disconnection side view, (B) is a perspective view which expands and shows a magnetic force generation mechanism. (A), (B), and (C) are perspective views showing other types of magnetic force generation mechanisms in the apparatus of FIG. (A) and (B) are perspective views showing still another type of magnetic force generation mechanism in the apparatus of FIG. It is a general | schematic cutting side view which shows the other form of implementation of this invention. It is a general | schematic cutaway side view which shows other form of implementation of this invention. It is a general | schematic cutaway side view which shows other form of implementation of this invention. It is a general | schematic cutaway side view which shows other form of implementation of this invention. It is a block diagram which shows the feedback control system based on the distortion amount of a giant magnetostrictive element as an example of the control system for controlling the damping force in the variable damping device of this invention. It is a block diagram which shows the feedback control system based on the intensity | strength of the magnetic field generated from a giant magnetostrictive element as another example of the control system for controlling the damping force in the variable damping device of the present invention. It is a cutting | disconnection side view which shows the outline of an example of the variable attenuation apparatus used conventionally. The electromagnetic transducer for magnetic force control based on the inverse magnetostriction effect proposed in the past is shown. (A) shows the initial state, and (B) shows the state in which the piezoelectric element is energized and expanded and deformed. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Casing 3 Piston rod 4 Piston 5a, 5b Fluid chamber 6 Magnetic fluid 7 Passage 21 Magnetic force generation mechanism 22 Piezoelectric element 23 Giant magnetostrictive element 27 Orifice (passage)
28 Bypass pipe (passage)

Claims (6)

A piston with a piston rod is slidably accommodated in a casing, two fluid chambers partitioned by the piston are formed in the casing, and the fluid chambers are communicated with each other through a required passage. A magnetic fluid filled in each fluid chamber passes through the passage, and further includes a super magnetostrictive element and a piezoelectric element. The magnetostrictive element is distorted by deformation when the piezoelectric element is energized to apply a magnetic field. A variable damping device having a configuration in which a magnetic force generation mechanism configured to generate the above is provided in a position near the fluid chamber or a position near the passage. The magnetic force generation mechanism has a giant magnetostrictive element arranged at one end side in the deformation direction when the piezoelectric element is energized, and the piezoelectric element and the giant magnetostrictive element are constrained from both end sides to extend and deform when the piezoelectric element is energized. The variable damping device according to claim 1, wherein a magnetic field can be generated by applying a strain in the compression direction to the giant magnetostrictive element. The magnetic force generation mechanism is such that a giant magnetostrictive element is integrally joined to a surface along a deformation direction when a piezoelectric element is energized, and strain is applied to the giant magnetostrictive element along with the deformation when the piezoelectric element is energized. The variable attenuation device according to claim 1, wherein a magnetic field can be generated. 4. The variable damping device according to claim 3, wherein the piezoelectric element has a flat plate shape and the giant magnetostrictive element has a flat plate shape, which are laminated and joined together to form a magnetic force generating mechanism. A rod-shaped giant magnetostrictive element is inserted and placed inside a cylindrical piezoelectric element that deforms in the axial direction when energized, and the inner surface of the piezoelectric element and the outer surface of the giant magnetostrictive element are joined together to generate a magnetic force. The variable damping device according to claim 3, wherein: A rod-shaped piezoelectric element that deforms in the axial direction when energized is inserted inside the cylindrical giant magnetostrictive element, and the outer surface of the piezoelectric element and the inner surface of the giant magnetostrictive element are joined together to form a magnetic force. 4. The variable damping device according to claim 3, wherein a generation mechanism is formed.

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