Electrical generator or motor structure – Non-dynamoelectric – Piezoelectric elements and devices
Reexamination Certificate
2001-05-09
2003-05-27
Ramirez, Nestor (Department: 2834)
Electrical generator or motor structure
Non-dynamoelectric
Piezoelectric elements and devices
C257S420000, C257S415000, C248S550000, C318S114000
Reexamination Certificate
active
06570298
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a vibration control device having a solid-state actuator and its driving method, which can be used in an active vibration-eliminating device for actively eliminating environmental vibration of a floor, etc. from precision equipment and a microvibration applying device for carrying out a simulating operation on a microvibration environment and for measuring the microvibration sensitivity of a device.
BACKGROUND OF THE INVENTION
In recent years, solid-state actuators, such as piezo-elements and magnetostrictive elements, have been used in various fields, such as vibration controlling operations for vibration protection and vibration elimination and vibration generating operations. However, these solid-state actuators have a relatively small displacement when used independently, with the result that in most cases, they fail to achieve a desired object. For this reason, the application of a vibration control device in which a displacement enlarging mechanism using a large-diameter piston and a small-diameter piston with a gap filled with liquid and a solid-state actuator are combined has been proposed (for example, see Japanese Unexamined Patent Publication No. 301354/1995 (Hei 7-301354)). Such a vibration control device using combined displacement enlarging mechanism and solid-state actuator makes it possible to enlarge the displacement of the solid-state actuator in accordance with the ratio of areas of the large-diameter piston and the small-diameter piston, and consequently to obtain the corresponding output from the small-diameter piston side.
The above-mentioned vibration control device having the displacement enlarging mechanism and the solid-state actuator is superior in the vibration-blocking performance (active vibration blocking performance) in low frequency bands at the time when an active controlling operation is carried out while the solid-state actuator is being driven. However, since the active controlling operation potentially possesses the possibility of generating vibration, it is difficult to apply the active controlling operation to vibration control at high frequency bands. Therefore, at high frequency bands, it is preferable to carry out the vibration controlling operation by effectively utilizing a natural vibration-blocking characteristic (passive vibration-blocking characteristic) that the vibration control device itself possesses. However, the above-mentioned vibration control device having the displacement enlarging mechanism and the solid-state actuator has a comparatively high natural frequency, and fails to provide a sufficient passive vibration-blocking characteristic at high frequency bands. Moreover, there have been ever-increasing demands for small-size vibration control devices having solid-state actuators.
Here, the above-mentioned vibration control device having the displacement enlarging mechanism and the solid-state actuator fails to generate a great output displacement since the displacement of the solid-state actuator is small and since it is difficult to provide a great difference in the areas of the large-diameter piston and the small-diameter piston. For this reason, the above-mentioned vibration control device cannot be applied to operations, such as position control and attitude control, in which, in particular, a greater displacement is required. Moreover, in the above-mentioned vibration control device, in the case when a control target member is comparatively soft (in particular, when the rigidity of the supporting system supporting the actuator and the control target member is not sufficient), it is sometimes difficult to carry out an appropriate controlling operation on the control target member since the displacement is absorbed by the deformation of the control target member.
Moreover, the above-mentioned Japanese Unexamined Patent Publication No. 301354/1995 (Hei 7-301354)) does not clearly describe about a means for carrying out the vibration controlling operation with multiple-dimensional, multiple degrees of freedom in the vibration control device having the displacement enlarging mechanism and the solid-state actuator.
SUMMARY OF THE INVENTION
The main object of the present invention is to provide a vibration control device and a driving method suitable for such a device, which has a comparatively small size, and has a low natural frequency so that it exerts a superior passive vibration-blocking performance at high frequency bands, while maintaining a superior active vibration-blocking performance at low frequency bands.
Moreover, another object of the present invention is to provide a vibration control device and a driving method suitable for such a device, which can generate a comparatively great output displacement.
Still another object of the present invention is to provide a vibration control device and a driving method suitable for such a device, which has a low natural frequency so that it exerts a superior passive vibration-blocking performance at high frequency bands, while maintaining a superior active vibration-blocking performance at low frequency bands, and also carries out the vibration controlling operation with multiple-dimensional, multiple degrees of freedom.
In order to achieve one of the above-mentioned objects, a vibration control device in accordance with one aspect of the present invention is provided with: a displacement enlarging mechanism having first and second movable sections that are arranged so that a displacement inputted to the first movable section is enlarged and taken out from the second movable section; a solid-state actuator that is placed on a side opposite to the second movable section with respect to the first movable section, and is allowed to shift in a direction so as to move the first movable section of the displacement enlarging mechanism based upon an electric signal supplied thereto; and an inside elastic member that is placed between the second movable section and the solid-state actuator in series therewith.
In this vibration control device, a solid-state actuator is placed on the first movable section side of the displacement enlarging mechanism which enlarges the displacement inputted to the first movable section, and outputs the resulting displacement from the second movable section. The application of such a displacement enlarging mechanism makes it possible to enlarge the displacement of the solid-state actuator. For this reason, it is possible to provide a superior active vibration blocking performance in low frequency bands when, for example, a vibration controlling operation or a vibration-eliminating operation is carried out.
In a conventional active vibration-eliminating device using a solid-state actuator such as a piezo-electric element, an actuator having a multiple laminated layers of solid-state elements has been used so as to gain a longer stroke of the solid-state actuator. For example, in a solid-state actuator using piezo elements, piezo elements of d33-type are laminated as high as 10 cm so as to provide a displacement of approximately 70 ìm. In contrast, in the present invention, when a displacement enlarging mechanism having a displacement enlarging rate of 10 times is used, it is possible to easily obtain an amount of distortion of 150 ìm by using laminated piezo elements having a length of 20 mm. This makes it possible to cut costs greatly and consequently to devote greatly to the promotion of active vibration control devices.
Moreover, the application of the displacement enlarging mechanism makes it possible to easily obtain a greater displacement so that the vibration control device can also be applied to the positional control and attitude control, which have not been realized without using an air actuator. Furthermore, in the case when a control target member is comparatively soft (in particular, when the rigidity of the supporting system supporting the actuator and the control target member is not sufficient), a vibration control device without a displacement enlarging mechanism
Aguirrechea J.
Rosenthal & Osha L.L.P.
Tokkyokiki Co., Ltd.
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