JP2009022121A - Linear motor and linear actuator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a linear motor and a linear actuator whose overall length is not significantly increased even if the stroke is lengthened. <P>SOLUTION: A peripheral yoke forme of a magnetic material is placed in proximity to the peripheral portion of an exciting coil. The yoke and the coil can be moved relative to each other. As a result, it is possible to obtain a linear motor whose overall length is not significantly increased even if a stroke is lengthened. Further, it is possible to obtain an actuator short in overall length whose sectional area is increased as compared with a conventional case and whose overall length is increased only by an amount equivalent to an increase in the stroke even if the stroke is lengthened. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to, for example, a linear motor used in a precision positioning system and a linear actuator using the linear motor, and in particular, even if the stroke is lengthened, the total length is only increased by about the stroke increase, and has a small cross-sectional area and It relates to the device designed to shorten the overall length.

As a linear motor capable of non-contact driving, there are those disclosed in Patent Document 1, Patent Document 2, and Patent Document 3, for example.
JP 2005-328586 A JP 2001-333567 A Japanese Patent Laid-Open No. 10-313566

In the case of the linear motors described in Patent Document 1, Patent Document 2, and Patent Document 3, there is a problem that sufficient thrust cannot be obtained, and a steep peak of the magnetic field near the interface between adjacent permanent magnets. As a result, there is a problem that the magnetic field distribution has a non-uniform magnetic field distribution, which causes a variation in thrust and lowers positioning accuracy.

Accordingly, the present patent applicant has filed patent applications relating to Japanese Patent Application No. 2007-28147 and Japanese Patent Application No. 2007-51051 as solutions to these problems (these two cases have not been disclosed). The configuration of the linear motor disclosed in these patent applications will be described below.

First, the linear motor disclosed in the patent application related to Japanese Patent Application No. 2007-28147 has a configuration as shown in FIG. First, there is a stator 101. This stator 101 includes a yoke 103, three U-phase coils 121, a V-phase coil 123, a W-phase coil 125 and the like arranged on the inner peripheral side of the yoke 103. It is composed of The yoke 103 is made of a magnetic material having a high magnetic permeability, for example, soft iron. Guide members 107 and 109 are attached to both ends of the yoke 103.

In this case, a three-phase coil drive system is adopted, and the above three coils having different phases, that is, a U-phase coil 121, a V-phase coil 123, and a W-phase coil 125 are combined into one set. A set is installed. In this case, the driving of the U-phase coil 121, the V-phase coil 123, and the W-phase coil 125 is a sine wave drive.

In addition, five permanent magnets 113 are connected to the inner peripheral side of the U-phase coil 121, V-phase coil 123, and W-phase coil 125. Shafts 115 and 117 are connected to both ends of the permanent magnet 113. The shafts 115 and 117 are disposed through the guide members 107 and 109.

  Next, the linear motor disclosed in the patent application related to Japanese Patent Application No. 2007-51051 is configured as shown in FIGS. First, there is a stator 201. The stator 201 includes a yoke 203 and a coil 205 installed on the inner peripheral side of the yoke 203. The coil 205 is composed of four sets of three-phase coils 207, and the three-phase coil 207 is composed of a U-phase coil 207a, a V-phase coil 207b, and a W-phase coil 207c. The yoke 203 is made of a magnetic material having a high magnetic permeability, for example, soft iron. Guide members 209 and 211 are attached to both ends of the yoke 203.

A mover 213 is accommodated and arranged on the inner peripheral side of the coil 205 in a state in which it can move in the left-right direction in the figure. The mover 213 has a configuration in which a plurality (six in the case of this embodiment) of permanent magnets 215 having a cylindrical shape are stacked and arranged. Further, shafts 217 and 219 are attached to both ends of the plurality of permanent magnets 215. The shafts 217 and 219 are disposed through the guide members 209 and 211.

The shaft 219 is provided with a linear scale portion 243. That is, a flat portion 241 is provided on a part of the shaft 219, and a linear scale portion 243 is provided on the flat portion 241. The linear scale portion 243 has a striped configuration and a scale function, and is provided by plating and etching. The guide member 211 is formed with a rectangular opening 245. Reference numerals 231, 233, and 235 in the figure indicate A-phase sensors, B-phase sensors, and Z-phase sensors.

The conventional configuration has the following problems. That is, in the case of the conventional linear motor, there is almost no problem in the case of a short stroke, but there is a problem that the total length is significantly increased when the stroke is lengthened. Details will be described below.
For example, in the case of the linear motor shown in FIG. 5, even if the permanent magnet 113 arranged on the inner peripheral side of the yoke 103 moves, the magnetic attractive force between the permanent magnet 113 and the yoke 103 does not change ( When the permanent magnet 113 approaches the end of the yoke 103, the magnetic flux distribution becomes non-uniform and a large magnetic attractive force is generated. Therefore, the design is such that the end of the permanent magnet 113 can move only slightly before the end of the yoke 103. If the stroke is to be lengthened, the permanent magnet 113 must be lengthened by the stroke, and the yoke 103 must be lengthened by an amount corresponding to the length of the permanent magnet 113 and the amount of movement of the permanent magnet 113 increased. . That is, it is necessary to increase the length of the yoke 103 by twice the increasing stroke, and as a result, when the stroke is increased, the entire length of the linear actuator is abruptly increased.
In the case of the linear actuator shown in FIGS. 6 and 7, the linear actuator shown in FIG. 5 is provided with a linear scale 243 (linear encoder). The total length of the linear actuator is even longer.

The present invention has been made based on such points, and an object of the present invention is to provide a linear motor and a linear actuator that do not significantly increase the overall length even if the stroke is lengthened.

In order to solve the above-mentioned problem, the linear motor according to claim 1 of the present invention has an outer peripheral magnetic material yoke arranged in the vicinity of the outer periphery of the exciting coil, and the outer peripheral magnetic material yoke and the exciting coil can move relative to each other. It is characterized by being.
According to a second aspect of the present invention, the linear motor according to the first aspect is characterized in that an end magnetic material yoke is disposed at an end of the outer peripheral magnetic material yoke.
According to a third aspect of the present invention, there is provided the linear motor according to the first aspect, wherein a groove is cut out in a part of the outer peripheral magnetic material yoke.
According to a fourth aspect of the present invention, there is provided the linear motor according to the third aspect, wherein the outer peripheral magnetic yoke is housed in a housing.
According to a fifth aspect of the present invention, the linear motor according to the first aspect is characterized in that a sliding guide is used on the inner peripheral side of the exciting coil.
According to a sixth aspect of the present invention, there is provided the linear motor according to the fifth aspect, wherein the sliding guide is made of a nonmagnetic metal.
According to a seventh aspect of the present invention, in the linear motor according to the sixth aspect, a sintered body is used for the sliding surface of the sliding guide.
The linear motor according to claim 8 is the linear motor according to claim 7, wherein the surface of the sintered body is coated with Teflon (registered trademark) resin.
According to a ninth aspect of the present invention, there is provided the linear motor according to the first aspect, wherein a guide holder is provided before and after the exciting coil, and the guide holder is connected using a connecting member. Is.
The linear motor according to claim 10 is the linear motor according to claim 9, wherein a linear scale is attached to the connecting member.
A linear actuator according to an eleventh aspect uses the linear motor according to any one of the first to tenth aspects.

As described above, in order to solve the above-described problem, the linear motor according to claim 1 of the present invention has the outer peripheral magnetic material yoke disposed in the vicinity of the outer periphery of the exciting coil, and the outer peripheral magnetic material yoke, the exciting coil, and the like. Since it is configured to be capable of relative movement, the total length of the linear motor can be shortened. That is, in order to increase the stroke, it is only necessary to increase the number of permanent magnets. In this case, the total length of the linear motor only needs to be increased by the amount of increase of the permanent magnets, that is, by the stroke. In addition, compared with a conventional typical single-axis actuator, which is a rotary motor and an actuator using a ball screw, at least the rotation motor can be significantly shortened by an amount that is unnecessary.
According to a second aspect of the present invention, in the linear motor according to the first aspect, the end magnetic material yoke is disposed at the end of the outer peripheral magnetic material yoke. Since the portion comes close to the end of the linear motor, magnetic flux leakage can be prevented from the end and a magnetic circuit can be formed, and the magnetic flux density of the permanent magnet at the end can be improved.
According to a third aspect of the present invention, in the linear motor according to the first aspect of the present invention, since the groove is notched in a part of the yoke made of the outer peripheral magnetic material, the movement of the movable part can be easily taken out. be able to.
According to a fourth aspect of the present invention, in the linear motor according to the third aspect of the present invention, since the outer peripheral magnetic material yoke is housed in the housing, the outer peripheral magnetic material yoke is maintained in the cylindrical shape. Accordingly, a small linear motor with a narrow gap can be obtained.
Further, the linear motor according to claim 5 is the linear motor according to claim 1, wherein a sliding guide is used on the inner peripheral side of the exciting coil, so that the gap between the permanent magnet and the exciting coil is increased. It can be stabilized in a narrow space, and it is possible to reduce the size of the linear motor.
According to a sixth aspect of the present invention, in the linear motor according to the fifth aspect, since the sliding guide is made of a nonmagnetic metal, the generated thrust can be secured without disturbing the flow of magnetic flux. Further, by using a non-magnetic metal, good thermal conductivity can be obtained and a larger current can be flowed, which greatly contributes to miniaturization as a linear motor.
According to a seventh aspect of the present invention, in the linear motor according to the sixth aspect, since the sintered body is used for the sliding surface of the sliding guide, a smoother operation can be provided.
Further, the linear motor according to claim 8 is the linear motor according to claim 7, wherein the surface of the sintered body is coated with Teflon (registered trademark) resin, so that a smoother operation can be obtained. It can be done.
According to a ninth aspect of the present invention, in the linear motor according to the first aspect, a guide holder is provided before and after the exciting coil, and the guide holder is connected by using a connecting member. Therefore, for example, a configuration in which the sliding guide is divided into two parts can also be realized.
The linear motor according to claim 10 is the linear motor according to claim 9, wherein a linear scale is attached to the connecting member, so that a desired linear encoder can be configured without requiring a new plane space. In this case, the total length of the linear actuator is not increased.
Further, since the linear actuator according to claim 11 is configured to use the linear motor according to any one of claims 1 to 10, the cross-sectional area is increased as compared with the conventional example, but the stroke is lengthened. Thus, it is possible to obtain an actuator having a short overall length in which the overall length is increased only by an approximately stroke increase.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. First, there is a housing 1, and a yoke 3 made of an outer peripheral magnetic material is accommodated and disposed inside the housing 1. Further, end magnetic material yokes 5 and 7 are provided at both ends of the outer peripheral magnetic material yoke 3. A magnet holder 9 is installed on the inner peripheral side of the yoke 3 made of the outer peripheral magnetic material, and a plurality of permanent magnets 11 are accommodated in a stacked and arranged state on the inner peripheral side of the magnet holder 9. Yes.

  Guide holders 13 and 13 are installed between the magnet holder 9 and the outer peripheral magnetic material yoke 3, and the guide holders 13 and 13 are made of a nonmagnetic metal (in this embodiment). In this case, a phosphor bronze sliding guide 15 is provided. An exciting coil 17 is installed on the outer peripheral side of the sliding guide 15. The excitation coil 17 is composed of three sets of three-phase coils 19, and the three-phase coil 19 is composed of a U-phase coil 19a, a V-phase coil 19b, and a W-phase coil 19c. Then, by switching the U-phase coil 19a, the V-phase coil 19b, the W-phase coil 19c and the direction in which the current flows, the coil 17 and the movable part integrated therewith are moved in either the left or right direction in the figure. It is something to be made.

  A part of the guide holders 13 and 13 is exposed and arranged outside through the opening 21 formed in the housing 1 and the yoke 3 made of the outer peripheral magnetic material, and is connected through the connecting member 23. Has been. A slider 25 is attached to the connecting member 23. A rail 27 is laid on the housing 1, and the slider 25 is installed so as to reciprocate along the rail 27.

A linear scale 29 is attached to the slider 25 side. A circuit board 31 is installed on the housing 1 side, and an encoder sensor 33 is installed on the circuit board 31. A flat cable 35 is installed on the housing 1 side.

As described above, according to the present embodiment, the following effects can be obtained.
First, in the case of the present embodiment, the outer peripheral magnetic material yoke 3 and the exciting coil 17 at the outer peripheral portion of the exciting coil 17 are used to stop and fix the relative movement between the outer magnetic material yoke 3 and the permanent magnet 11. Since it is configured to be able to move relative to the linear motor, the overall length of the linear motor can be shortened.
For example, in order to increase the stroke, it is only necessary to increase the permanent magnet 11, and in that case, the total length of the linear motor only needs to be increased by the increase of the permanent magnet 11, that is, the stroke.
Compared with a conventional rotary motor that is a typical single-axis actuator and an actuator using a ball screw, at least the rotation motor can be significantly shortened.
Further, since the end magnetic material yokes 5 and 7 are provided at the end of the magnetic material yoke 3 near the outer peripheral portion, the end of the permanent magnet 11 comes close to the end of the linear motor. Magnetic flux can be prevented while preventing magnetic flux leakage, and the magnetic flux density of the permanent magnet 11 at the end can be improved.
Further, when the exciting coil 17 side is a movable part and the permanent magnet 11 side is a fixed part, it is necessary to take out the force of the linear motor from the movable part inside the fixed part. Therefore, in the case of the present embodiment, the opening 21 is formed in a part of the housing 1 and the yoke 3 made of the outer peripheral portion magnetic material, whereby the movement of the movable portion can be taken out.
In addition, when a part of the outer peripheral magnetic material yoke 3 is cut out to form the opening 21, the circular shape of the outer peripheral magnetic material yoke 3 is easily distorted. Since the outer peripheral magnetic material yoke 3 is inserted into the housing 1 having a circular hole, the circular shape of the outer peripheral magnetic yoke 3 can be maintained. Thereby, a small gap small linear motor can be obtained.
In the present embodiment, since the exciting coil 17 is arranged around the sliding guide 15, the gap between the permanent magnet 11 and the exciting coil 17 can be narrowed and stabilized. As a result, the linear motor can be miniaturized.
In the present embodiment, a portion of the phosphor bronze sliding guide 15 is press-fitted into the front and rear guide holders 13 and 13 to fix the exciting coil 17 and the magnet holder 9 into which the permanent magnet 11 is inserted. Since the sliding guide portion serving as the guide member is configured, the linear motor can also be reduced in size.
Further, in this case, the generated thrust can be secured without disturbing the flow of magnetic flux by making the sliding guide portion non-magnetic. Further, by using a non-magnetic metal, good thermal conductivity can be obtained and a larger current can be flowed, which greatly contributes to miniaturization as a linear motor.
In addition, since the linear scale 29 is attached under the connecting member 23 and the encoder sensor 33 is disposed under the linear scale 29, a desired linear encoder can be configured without requiring a new plane space. In this case, the total length of the linear actuator is not increased.
A part of the guide holders 13 and 13 is exposed through the opening 21 of the yoke 3 made of the outer peripheral magnetic material and is connected by a connecting member 23. Further, a part of the guide holders 13 and 13 is a slider. 25, thereby achieving a function of preventing rotation of the cylindrical sliding guide portion, and a load can be placed on the slider 25 and driven for positioning.


In addition, although the cross-sectional area is increased as compared with the prior application example, it is possible to obtain a linear actuator having a short overall length, which can increase the overall length only by the stroke increase even if the stroke is lengthened.

Next, a second embodiment of the present invention will be described with reference to FIG. In the case of the second embodiment, a sintered body layer 51 is formed on the sliding surface of the sliding guide 15 made of phosphor bronze in the first embodiment. The peripheral surface is thinly coated with Teflon (registered trademark) resin. In the drawing, a coating portion of Teflon (registered trademark) resin is denoted by reference numeral 53.
Other configurations are the same as those in the first embodiment, and the same portions are denoted by the same reference numerals and description thereof is omitted.

Therefore, the same effect as in the case of the first embodiment can be obtained, and a smoother operation can be provided.
There are two types of lubricants, liquid lubricants and solid lubricants such as the above-mentioned Teflon (registered trademark) resin, but in the case of liquid lubricants, there are also problems such as scattering. Is preferred.

The present invention is not limited to the first and second embodiments.
For example, in the case of the first and second embodiments, the phosphor bronze sliding guide 15 is formed by forming a sintered body layer 51 on a phosphor bronze plate and placing Teflon (registered trademark) resin thereon. It is coated and formed into a cylindrical shape (C shape). However, products with a long length have a high press pressure, resulting in decreased productivity. Therefore, a configuration in which the sliding guide 15 is divided into two parts is conceivable. Even in this case, the guide holders 13 and 13 before and after the exciting coil 17 are connected by using an external connecting member 23. For example, even if the sliding guide 15 is divided into two, the guide holders 13 and 13 are externally connected. Therefore, even the sliding guide 15 divided into two can be integrated.
Needless to say, even if the movable portion and the fixed portion are interchanged, the same function is exhibited.
In addition, the illustrated configuration is merely an example and is not limited thereto.

The present invention relates to a linear motor and a linear actuator using the linear motor, and in particular, even if the stroke is lengthened, the total length is only increased by about the stroke increase, and the device is devised so as to have a small cross-sectional area and a short total length. For example, it is suitable for a linear actuator used in a precision positioning system.

It is a figure which shows the 1st Embodiment of this invention, and is sectional drawing which shows the structure of a linear actuator (II sectional drawing of FIG. 2). FIG. 2 shows a first embodiment of the present invention, and FIG. 2 is a sectional view taken along line II-II in FIG. It is a figure which shows the 1st Embodiment of this invention, and is III-III sectional drawing of FIG. It is a figure which shows the 2nd Embodiment of this invention, and is sectional drawing which shows the structure of the linear actuator equivalent to FIG. 3 which shows 1st Embodiment. It is a figure which shows a prior application example, and is a longitudinal cross-sectional view of a linear actuator. It is a figure which shows a prior application example, and is a longitudinal cross-sectional view of a linear actuator. FIG. 7A is an enlarged cross-sectional view showing a part a of FIG. 6, FIG. 7B is a cross-sectional view taken along line bb of FIG. 7A, and FIG. These are cc arrow directional views of Fig.7 (a).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Housing 3 Peripheral part magnetic material yoke 5 End part magnetic material yoke 7 End part magnetic material yoke 9 Magnet holder 11 Permanent magnet 13 Guide holder 15 Sliding guide 17 Excitation coil 19 Three-phase coil 21 Opening part 23 Connecting member 25 Slider 27 Rail 29 Linear scale 33 Encoder sensor 51 Sintered body layer 53 Teflon (registered trademark) resin coating part

Claims (11)

A linear motor characterized in that an outer peripheral magnetic material yoke is disposed in the vicinity of an outer periphery of an exciting coil, and the outer peripheral magnetic material yoke and the exciting coil are capable of relative movement. The linear motor according to claim 1,
A linear motor comprising an end magnetic material yoke disposed at an end of the outer peripheral magnetic material yoke. The linear motor according to claim 1,
A linear motor characterized in that a groove is cut out in a part of the yoke made of the outer peripheral portion magnetic material. The linear motor according to claim 3,
A linear motor characterized in that the outer peripheral magnetic material yoke is housed in a housing. The linear motor according to claim 1,
A linear motor characterized in that a sliding guide is used on the inner peripheral side of the exciting coil. The linear motor according to claim 5,
A linear motor characterized in that the sliding guide is made of non-magnetic metal. The linear motor according to claim 6,
A linear motor using a sintered body on a sliding surface of the sliding guide. The linear motor according to claim 7, wherein
A linear motor characterized in that a surface of the sintered body is coated with Teflon (registered trademark) resin. The linear motor according to claim 1,
Guide motors are provided before and after the exciting coil, respectively, and the guide holders are connected using a connecting member. The linear motor according to claim 9, wherein
A linear motor, wherein a linear scale is attached to the connecting member. A linear actuator using the linear motor according to claim 1.

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