JPH03169086A - Magnetostrictive actuator - Google Patents

Abstract

PURPOSE:To improve the abrasion resistance of a magnetostrictive material by arranging the constitution such that the whole periphery of the magnetostrictive material is coated with self lubricating agent. CONSTITUTION:This is put in such structure that the whole periphery of a magnetostrictive actuator is coated with self lubricating material 31-33. For the self lubricating material 31-33, if the use temperature is room temperature about 100 deg.C, metallic plating such as In, Cu, etc., is suitable, and if the use temperature is higher temperature, ceramic coating such as carbon, chromium oxide, titanium oxide, etc., is suitable. For the coating method, baking, plating, deposition, sputtering, flame-coating, alloying, or the like is used. Hereby, an electrostrictive actuator, wherein abrasion resistance is improved, can be obtained.

Description

[Detailed Description of the Invention] [Industrial Field of Application] [Prior Art] Recently, vibrators. Magnetostrictive elements are increasingly being used in place of piezoelectric elements as movable elements in acoustic equipment and displacement actuators. This trend is due to the emergence of magnetostrictive elements that are superior to piezoelectric elements in terms of energy density, electromechanical conversion coefficient, usable temperature, etc. Such magnetostrictive elements, especially rare-class magnetostrictive elements, are increasingly attracting attention. Therefore, we have developed a conventional magnetostrictive actuator using such a magnetostrictive element. This will be explained with reference to the drawings. An example is shown in FIG. The magnetostrictive actuator 1 shown in the figure is roughly composed of a cylindrical magnetostrictive material 3 in a cylinder 2, and a ram 4 for outputting the magnetostrictive displacement χ of the magnetostrictive material 3 to the outside. Specifically, a coil 6 wound around a bobbin 5 is provided on the outer periphery of the magnetostrictive material 3, and a bias magnet (usually a permanent magnet) 7 is further provided on the outer periphery of this coil 6. A coil 6, a bias magnet 7, and yokes 81 and 82 of the magnetostrictive material 3 are provided at both ends of the magnetostrictive material 3 in the potato direction. The yoke 81 at the left end in the figure is in contact with the cylinder 2 and covers the fixed side of the magnetostrictive actuator 1. On the other side, the yoke 81 at the left end in the figure is
The left end in the drawing contacts the magnetostrictive material 3, and the right end in the drawing contacts the ram 4 via a retainer 9 made of a non-magnetic material. The ram 4 protrudes outward from an opening at the right end of the cylinder 2 in a slidable manner. Furthermore, retainer 9 and Shinonda 2
An elastic body 10 is housed between the magnetostrictive material 3 and the
A compressive force is constantly applied via the retainer 9 and the yoke 82. This compressive force is the prestress in the magnetostrictive material 3. As is well known, this prestress and the bias magnetic field generated by the bias magnet 7 have the effect of improving the magnetostrictive properties of the magnetostrictive material 3. Such a magnetostrictive actuator 1 becomes a vibrator when an alternating current or pulsating current is passed through the coil 6. Conversely, if a direct current is applied to the coil 6, the magnetostrictive actuator 1 becomes a displacement actuator. In the magnetostrictive actuator 1 shown in the figure, the length of the magnetostrictive material 3 in the longitudinal direction is shorter than the length of the coil 6 in the longitudinal direction. The reason for this is in the magnetic circuit in which the magnetic flux from the coils 6 and the bias magnet 7 passes through the yokes 81 and 82 and the magnetostrictive material 3. This is because consideration is given so that the magnetic fluxes within the magnetostrictive material 3 are parallel.

Problems to be Solved by the Invention] Magnetostrictive elements (magnetostrictive materials) have the above-mentioned advantages compared to piezoelectric elements (piezoelectric materials).

However, even such magnetostrictive materials are not without problems. One of the biggest problems is that magnetostrictive materials tend to wear out easily.This can be summarized as follows.

(1) Side wear Magnetostrictive materials expand and contract due to changes in the magnetic field applied to them.

For example, as can be seen from the above example of the conventional magnetostrictive actuator, when the magnetostrictive material expands and contracts, the bobbin and the magnetostrictive material come into contact, causing wear on the side surfaces of the magnetostrictive material that are prone to wear.

(2) End face wear When an alternating magnetic field is applied to a magnetostrictive material, the penetration depth of the magnetic flux is determined by the frequency of the alternating magnetic field.

In other words, the higher the frequency. The penetration depth of the magnetic flux becomes shallower (this is the so-called skin effect). Therefore, when an alternating magnetic field is applied, the strain on the end face of the magnetostrictive material differs between the shaft center portion and the shaft peripheral portion. As a result, uniform deformation does not occur at the end face of the magnetostrictive material. In other words, the end face of the magnetostrictive material and the yoke (or ram, etc. in some cases) that abuts the magnetostrictive material come into uneven contact, and as a result, wear of the end face abutting portion is accelerated.

The above-mentioned side and end surface wear occurs more frequently in the magnetostrictive material of the bristless type magnetostrictive actuator.

In view of the problems of the prior art, it is an object of the present invention to provide a magnetostrictive actuator that can improve wear resistance.

[Means for Solving the Problems] In order to achieve the above object, the magnetostrictive actuator according to the present invention has a self-lubricating agent applied to the other Ff4 member that contacts the self-lubricating strained material around the entire circumference of the magnetostrictive material. A coating structure may also be used. Furthermore, a self-lubricating agent may be interposed between the magnetostrictive material and other components that come into contact with the magnetostrictive material. Note that in these three configurations, the self-lubricating material may be a low wear rate material.

E-effect The difference between the inventions of claim 1 and claim 2 is the use of the coating destination of the self-lubricating agent. If the invention of claim 1,
The coating target is a magnetostrictive material, and in the invention of local claim 2, the coating target is an object that comes into contact with the magnetostrictive material (in the conventional example, the bobbin 5). The invention of claim 3 is an intermediate aspect between the inventions of claims 1 and 2, in which a self-lubricating agent is interposed in the gap between the magnetostrictive material and the object that abuts the magnetostrictive material. In the invention of claim 4,
In the invention according to claims 1 to 3, the self-lubricating agent is a material with a low wear rate. This was done in view of the purpose of the invention, ie, reducing the wear of magnetostrictive materials.

[Examples] Examples of the present invention will be described below. The embodiment of claim 1 is:
The following elements can be exemplified in the configuration "III or I in which the entire circumference of the magnetostrictive material of the magnetostrictive actuator is coated with a self-lubricating agent".

(1) Self-lubricating material 2 If the operating temperature is room temperature to about 100 degrees Celsius, metal plating such as In or Cu is suitable. On the other hand, if the operating temperature is higher, a ceramic coating such as carbon, chromium oxide or titanium oxide is suitable.

(2) Coating method: This includes baking, plating,
This includes vapor deposition, sputtering, thermal spraying, and alloying.

The embodiment of claim 2 can exemplify the following constituent features in its configuration: "In the magnetostrictive actuator, other structural members that come into contact with the magnetostrictive material are coated with a self-lubricating agent."

(3) Self-lubricating material: Same as (1) above.

(4) Other components: For example, in the configuration example shown in FIG. 1 or 2, the bobbin 5, yoke 81, . It is 82. In short, it refers to other structural members that are in contact with the magnetostrictive material (Fig. 1 will be described in the experimental example described later).

The embodiment of claim 3 has the following configuration in its configuration: "In a magnetostrictive actuator, a self-lubricating agent is interposed between a magnetostrictive material and another component that comes into contact with the magnetostrictive material." Components can be exemplified.

(5) Other structural members: - Same as in (4).

(6) Self-lubricating agent 2 If the operating temperature is between room temperature and 100 degrees C, polymeric materials such as Teflon, metal soap, grease, etc.
Oil, molybdenum disulfide, etc. are suitable. On the other hand, if the operating temperature is higher, ceramics such as chromium oxide or titanium oxide are suitable.

(7) Intervention method 2 Spraying, coating, etc. correspond to this.

In the embodiment of claim 4, the following components can be exemplified in the configuration "the configurations of claims 1 to 3 in which the self-lubricating material is a low wear rate material".

(8) Low wear rate materials 2 In terms of (6) above, polymeric materials such as Teflon, metal soaps, molybdenum disulfide, etc. correspond to these materials.

Experimental example Some experimental results of the above examples are described below.

The experiment was conducted using the embodiment of the magnetostrictive actuator based on the present invention shown in FIG. The configuration of this figure 1 is as follows.
The configuration is substantially the same as the configuration shown in FIG. 2 described in the prior art section. Therefore, the differences between Figure 1 and Figure 2, which have already been explained, will be explained below, but explanations of the same parts will be given to avoid duplication. Description will be omitted below. The experimental examples are a conventional magnetostrictive actuator in which the side surface 31 and both end surfaces 32 and 33 of the magnetostrictive material 3 are made of untreated magnetostrictive material in the magnetostrictive actuator shown in FIG. The frequency of fretting was compared. The relative values of fretting frequency are shown in the table below. In addition, in FIG. 1, the drawing numbers 31, 32, and 33 also refer to the self-lubricating material or the low wear rate material according to claims 1 to 4.

Table 1 In this experimental example, as shown in the table above, the wear resistance of the magnetostrictive actuator according to the example is improved compared to the conventional magnetostrictive actuator (untreated Dy-Tb-Fe alloy).

[Effects of the Invention] As explained above, the magnetostrictive actuator according to the present invention has a structure in which a self-lubricating agent is coated or interposed around the entire circumference of the magnetostrictive material, so that the wear resistance of the magnetostrictive material can be improved. can.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an embodiment of a magnetostrictive actuator according to the present invention, and FIG. 2 is a sectional view of an example of a conventional magnetostrictive actuator. 1...Magnetostrictive actuator 2...Cylinder 3...Magnetostrictive Materials 31, 32, 33 - Self-lubricating material 4 - Ram 5 - Bobbin 6 - Coil 7 - Bias magnet 81, 82 - Yoke 9 - Retainer 10 - Elastic body χ magnetostrictive displacement

Claims (4)

[Claims] (1) A magnetostrictive actuator characterized by a structure in which the entire circumference of the magnetostrictive material of the magnetostrictive actuator is coated with a self-lubricating agent. (2) A magnetostrictive actuator characterized in that other components that come into contact with the magnetostrictive material are coated with a self-lubricating agent. (3) A magnetostrictive actuator characterized by a structure in which a self-lubricating agent is interposed between a magnetostrictive material and another component that comes into contact with the magnetostrictive material. (4) The magnetostrictive actuator according to claim 1, 2 or 3, wherein the self-lubricating material is a low wear rate material.