JPS62138071A - Linear motor - Google Patents

Abstract

PURPOSE:To increase the displacement of a clamping means, and to move an actuator easily on the release of the clamping means by providing a function mechanically amplifying the displacement of the length of a piezoelectric element as a drive source for the clamping means. CONSTITUTION:Voltage is applied to a piezoelectric effect element 1a, and levers 4a, 4b press guides 5a, 5b and an amplifying mechanism 6a is fixed. Voltage is applied to a piezoelectric effect element 1c, and the piezoelectric effect element 1c is extended, thus shifting an amplifying mechanism 6b in the left direction. Voltage is applied to a piezoelectric effect element 1b, and levers 4c, 4d press the guides 5a, 5b and the amplifying mechanism 6b is fastened. The levers 4a, 4b are detached from the guides 5a, 5b when the voltage of the piezoelectric effect element 1a is brought to zero, and the piezoelectric effect element 1c is shrunk and the amplifying mechanism 6a is moved in the left direction when the voltage of the piezoelectric effect element 1a is brought to zero. A series of said operation is repeated.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a beam near motor. More specifically, the present invention relates to a step-type linear motor that uses a piezoelectric element as a drive source and is capable of precise positioning.

Conventional technology Conventionally, what is widely known as a linear motor includes:
First, there is one that uses electromagnetic force. A linear motor like this uses electromagnetic force by combining an electromagnet and a coil, and can be realized relatively easily and inexpensively, but on the other hand, the power consumption is extremely large compared to the driving force. , precisely control the amount of displacement of the actuator (
The drawback is that it is difficult to sell wholesale.

In particular, the control of the displacement amount, that is, the positioning of the actuator, is difficult due to the limitations of the processing accuracy of electromagnets, even with step-type linear motors that are designed with emphasis on the control of the displacement amount.
The actuator positioning accuracy that can be achieved is 0.1mm.
The steps were the limit.

On the other hand, a step-type near moke using a piezoelectric element as a driving source of an actuator has been realized for use in applications requiring particularly precise position control. An example of a near motor using such a piezoelectric element is shown in FIG. 4, which is a schematic diagram.
A pair of annular clamp elements 42a and 42b are configured such that the shaft 41 passes through them, and these pair of clamp elements 4 are connected via coupling members 43a and 43b.
The actuator is composed of a telescopic element 44 that connects 2a42b. Clamp elements 42a, 42
b and the elastic element 44 are made of a material having a piezoelectric effect, and when a voltage is applied to the clamp elements 42a and 42b, the inner diameter of the clamp elements 42a and 42b is reduced, and the elastic element 44 expands and contracts parallel to the direction of movement of the actuator. Furthermore, each element is configured to individually control the applied voltage.

To briefly explain the operation of the near motor, first, when a voltage is applied to one of the clamp elements 42, for example 42a, the inner diameter of the clamp element 42a becomes smaller, and the shaft 41 is fastened to the actuator! 15 is fixed on the shaft 41. Next, a voltage is applied to the elastic element 44 to bring it into an expanded state. Then the other clamp element 4
After applying a voltage to 2b to bring it into a fastened state, the clamp element 4
After stopping the voltage application to 2a and releasing the fastened state,
The voltage application to the elastic element 44 is stopped to release the expanded state.

Through this series of operations, the actuator 45 moves from the clamp element 42a side toward the clamp element 42b side by a distance corresponding to the amount of expansion of the expandable element 44. By repeating this operation, the actuator 45
You can move only the desired nail.

A step-type linear motor using a piezoelectric element as described above can control the amount of movement of its actuator extremely precisely compared to one using electromagnetic force. That is, the amount of one expansion and contraction of the telescopic element that defines the amount of movement of the actuator is approximately several micrometers, and by counting the number of cycles of operation described above, it is possible to control the amount of movement on the order of micrometers. In addition, since the operation stroke always includes fastening of the guide means by the clamp means, displacement errors due to friction are also extremely small.

Problems to be Solved by the Invention The fastening of the guide means using a piezoelectric element as described above or by the clamping means of a near motor depends exclusively on deformation of the piezoelectric material constituting the clamping means. is extremely small; for example, in the actual example of the conventional linear motor mentioned above, the change in the inner diameter of the clamping means was about 5 μm for an applied voltage of 400 μm.

Therefore, in order to ensure that the actuator can move freely without applying voltage to the clamping means, the shaft serving as the guiding means is required to have extremely high dimensional accuracy. That is, in the above-mentioned example, since the change in the inner diameter of the clamping means due to voltage application is about 5 μm, the dimensional accuracy of the shaft surface must be 2.5 μm or less or smooth movement of the actuator will be hindered.

Therefore, when using a piezoelectric element or manufacturing a near motor, it is necessary to precisely finish the surface of the shaft while matching the clamp element with the actual shaft, which is an extremely complicated process. However, despite its excellent displacement control performance, it has not been possible to use electromagnetic force or replace it with the near motor.

The present invention utilizes a conventional piezoelectric element or a near motor.
It is an object of the present invention to provide a near motor that can be manufactured relatively easily and retains its advantages, except for the above-mentioned drawbacks.

Means for solving the problem The problem with the conventional piezoelectric element or near motor described above is that the deformation of the piezoelectric material is extremely small, ensuring free movement of the actuator when the clamping means is released. This required extremely high machining precision. Therefore, the present inventors adopted a structure that ensures free movement of the actuator when the clamping means is released by mechanically amplifying the displacement of the piezoelectric element provided in the clamping means. The present invention has been completed by making it possible to reduce the requirements for machining accuracy, reduce manufacturing costs while maintaining high displacement control ability, and at the same time make the operation even more reliable.

That is, according to the present invention, there is provided a linear motor comprising a guide means and an actuator that moves along the guide means, the actuator being provided with a pair of clamp means, each of the clamp means having a first piezoelectric element. and means for mechanically amplifying the amount of displacement in the length of the first piezoelectric element and fixing the actuator to the guide means by the displacement, further comprising means for fixing the actuator with respect to the guide means, and the actuator is further provided with a means for mechanically amplifying the displacement amount of the length of the first piezoelectric element and fixing the actuator to the guide means by the displacement; Provided is a linear motor characterized by comprising a second piezoelectric element interconnecting the actuators and expanding and contracting in a direction parallel to the moving direction of the actuator.

According to a preferred embodiment of the present invention, the guide means has at least one pair of opposing surfaces, and 1) [1] the actuator moves along the opposing inner side of the guide means; Can be configured to move.

Further, the fixing means includes a U-shaped support rigidly connected to one end of the first piezoelectric element, and a pair of abutting members tiltably attached to the legs of the support. The pair of abutting members are also connected to the other leg portions of the first piezoelectric element, and as the first piezoelectric element expands, the corresponding abutting members use the connecting portion with the support as a fulcrum. It is also possible to configure the guide member so that the actuator is tilted as shown in FIG.

Eave J The operation of the linear motor according to the present invention as described above will be explained. The first piezoelectric element pushes one end of the abutting member by expanding due to the application of a voltage, and the other end of the abutting member is also correspondingly displaced by this action. At this time, the distance from the tilting axis of the contact member to the connection part of the member with the piezoelectric element!
If the distance from the tilting axis to the part where the abutment member abuts the guide means is β<, the displacement of the abutment member at the abutment part with the guide means is equal to the displacement of the first piezoelectric element. It is magnified by 572 times the length displacement. Therefore, when the clamping means is released, the distance between the guide means and the abutting member is easily ensured, so when manufacturing the linear motor according to the present invention, high machining accuracy is not required as with conventional piezoelectric linear motors. .

The operation of the linear motor according to the present invention having such characteristics will be described in more detail with reference to examples below.

Embodiment FIG. 1 is a diagram schematically showing an example of a linear motor according to the present invention.

Piezoelectric elements 1 (LA, LB, LC) utilize a laminated piezoelectric element in which a ceramic piezoelectric material made of lead zirconate titanate, etc., and an internal electrode made of silver, palladium alloy, etc. are stacked in layers and integrated. . Furthermore, the length of this piezoelectric element 1 in the direction of expansion and contraction is 9 mm, and the expansion displacement when a DC voltage of 100 volts is applied is 6.5 mm.
μm1 The generated force at that time is 13 kg.

The clamping means 6a, 6b are hinges 2a to 2h.

It is composed of functional members such as sabots 3a and 3b and levers 4a to 4d, but in this embodiment, it is manufactured as an integral piece from a metal plate by electrical discharge machining. The material is piezoelectric effect element 1a
, lc is used, and the thickness is 2 mm.

The piezoelectric elements 1a to 1c, supports 3a and 3b, and levers 4a to 4d can be connected with an adhesive such as epoxy resin. In addition, guides 5a and 5b serving as guide means
was made by cutting a metal rod.

First, a mechanism for mechanically amplifying the displacement generated in the piezoelectric effect elements 1a and lc using the lever principle will be described. When a voltage is applied to the piezoelectric effect element 1a, its displacement moves in the direction of pushing up the lever 4a via the hinge 2a.

The lever 4a tilts using the hinge 2a. The displacement amplification factor n at this time is determined by the distance β between the hinges 2a and 2b and the length of the lever 4a shown in FIG.
It can be expressed as n-L/n. Lever 4a with the above-mentioned mechanism.

The contact portion of lever 4b expands outward, and the lever 4a
, 4b abut against and fix the guides 5a, 5b.

Next, the operation of the linear motor according to the present invention having the above-described structure will be explained. Furthermore, Fig. 2 shows a graph showing the timing of applying voltage to each of the piezoelectric elements 1a to IC, and Figs. 3(a) to 3(e) show the operation of each element of the linear motor step by step. Refer to and explain.

First, as shown in FIG. 3(a), a voltage is applied to the piezoelectric effect element 1a, and the levers 4a and 4b press the guides 5a and 5b to fix the amplification mechanism 6a. The voltage applied to each element at this time corresponds to the interval α-β on the time axis (horizontal axis) of the graph in FIG.

Next, as shown in FIG. 3, etc., a voltage is applied to the piezoelectric effect element IC, and the width of the piezoelectric effect element IC increases by 6.5 μm in the left and right directions, and the amplifier hi6b moves to the left. The voltage applied to each element at this time is based on the time axis (
It corresponds to between 6 and 1 on the horizontal axis).

Next, as shown in FIG. 3(C), a voltage is applied to the piezoelectric effect element 1b, and the levers 4c and 4d press the guides 5a and 5b to fix the amplification mechanism 6b. The voltage applied to each Yonago at this time corresponds to the range 1 to 6 on the time axis (horizontal axis) of the graph in FIG.

Next, as shown in FIG. 3(d), when the voltage of the piezoelectric effect element 1a is made zero, the levers 4a and 4b are separated from the guides 5a and 5b. The voltage applied to each element at this time corresponds to between 6 and 6 on the time axis (horizontal axis) of the graph in FIG.

Next, as shown in FIG. 3(e), when the voltage of the piezoelectric effect element IC is made zero, the width of the piezoelectric effect element IC is reduced by 6.5 μm, and the amplification mechanism 6a moves to the left. The voltage applied to each element at this time corresponds to a period between ε and ζ on the time axis (horizontal axis) of the graph in FIG.

Assuming that the series of operations shown in Fig. 3 (a) to (e) is one stroke, the actuator is 6.5 μm 1 paper 1 in the same figure.
Move from right to left in a plane.

The performance of this linear motor is voltage 100■, frequency 2, 5
When driven by applying a pulse voltage with a period of KHz, the speed was 12 mm 2 /sec and the traction force was 10 kg. Also, the positioning error is 2 μm for a movement of 100 mm.
Met.

Effects of the Invention As detailed above, the linear motor according to the present invention is equipped with a mechanism for mechanically amplifying the displacement of the length of the piezoelectric element, which is the driving force for the operation of the clamping means. The displacement at the contact portion with the guide means is large, facilitating movement of the actuator when the clamp means is released. Therefore, the machining accuracy required to manufacture this linear motor is sufficient for ordinary machining, and the manufacturing cost of the linear motor can be fully comparable to that of conventional electromagnetic linear motors. . In addition, the driving force as a motor has a sufficiently low loss compared to the power consumed, and at the same time, the precision of displacement control as a near motor using piezoelectric elements is better than that using conventional piezoelectric elements. Equally guaranteed.

In this way, linear motors whose displacement can be precisely controlled are used in many applications that require precise positioning, such as computer external storage devices using magnetic disks, printer head drive devices, XY plotters, and camera autofocus mechanisms. It can be used in equipment and has an extremely wide range of industrial applications.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view schematically showing an embodiment of a linear motor according to the present invention, and FIG. 2 is a time chart showing the timing of applying voltage to the piezoelectric element of the linear motor according to the present invention. Figures 3 (a) to (e) are diagrams showing the operation of the near motor shown in Figure 1 and shown in sequence, and Figure 4 is a cross-sectional view of an example of a conventional linear near motor using piezoelectric materials. FIG. (Main reference numbers) 1 (1a to lc)... Piezoelectric effect elements 2a to 2h... Hinge 3a, 3b... Base 4a to 4d... Lever 5a, 5b... Guide 5a, 5b... Clamping means 41. - Shafts 42a, 42b... Clamp element 43... Connection member 44... Expandable element

Claims (1)

[Claims] (1) A linear motor consisting of a guide means and an actuator that moves along the guide means, the actuator having a pair of clamp means, each of the clamp means having a first piezoelectric element and a first piezoelectric element. comprising means for mechanically amplifying the amount of displacement in the length of the first piezoelectric element and fixing the actuator to the guide means by the displacement; The linear motor described above, further comprising a second piezoelectric element connected to the actuator and expanding and contracting in a direction parallel to the moving direction of the actuator.