JP5306558B2 - Linear motor - Google Patents

Description

The present invention relates to a linear motor including a slide bearing disposed between a movable portion and a fixed portion, and a sliding member disposed eccentrically from the central axis of the fixed portion.

In a conventional linear motor, the shaft member (first sleeve) has N-pole and S-pole permanent magnets alternately formed along the axial direction in the interior thereof, and further improves thrust between the permanent magnets. A structure provided with a magnetic body (yoke) is employed. The coil surrounding the outer periphery of the shaft member is provided in the movable part, and the shaft member moves linearly relative to the movable part in the axial direction of the shaft member inside the movable part located on the outer peripheral side of the shaft member. A bearing for guiding the movement is provided. A linear motor having such a structure has a structure in which a cylindrical or quadrangular bearing and a movable part are arranged around a shaft member, and a minute gap is provided between the bearing and the shaft member to facilitate relative motion. (For example, refer to Patent Document 1).

Japanese Patent Laid-Open No. 9-182408 (page 4, FIG. 1)

Since the conventional linear motor is configured as described above, rattling and fluctuation occur between the bearing and the shaft member by a minute gap provided between the bearing and the shaft member. For example, in a shaft type linear motor in which a shaft that transmits thrust to the machine is provided in the movable part, there is a problem in that the positioning accuracy of the shaft tip part is lowered.

The present invention has been made to solve the above-described problems, and its purpose is to eliminate rattling and fluctuation between the bearing and the shaft member. For example, the positioning accuracy of the shaft tip portion of the shaft type linear motor Is to make it higher.

In the linear motor according to the present invention, the linear motor includes a fixed portion and a movable portion that is located inside the fixed portion and is provided so as to be relatively displaceable in the axial direction with respect to the fixed portion. A magnet part made up of a plurality of permanent magnets laminated in the axial direction, and a first sliding part made of a magnetic material that is arranged at one end of the magnet part and slides and guides the inside of the fixed part in the axial direction. The fixed portion is provided inside the fixed portion with a first bearing made of a non-magnetic material that is in contact with the inner surface of the fixed portion that slidably supports the first sliding portion, and provides a magnetic flux to its inner space. A plurality of coils that are generated and act on the magnet part to relatively displace the movable part, and the first sliding part has a central axis of the first sliding part formed from the central axis of the inner space formed by the coil. By being eccentrically arranged on the first bearing side and contacting the first bearing, Magnetic attraction force from the magnet to act on the eccentric direction.

According to the present invention, the positioning accuracy of the shaft tip portion of the shaft type linear motor can be increased, and the shaft type linear motor can be applied to precision electronic devices such as surface mounters and board inspection machines.

It is sectional drawing of the shaft type linear motor which shows Example 1 of this invention. It is a disassembled perspective view of the shaft type linear motor which shows Example 1 of this invention. It is a block diagram of the control part of the shaft type linear motor which shows Example 1 of this invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a structural diagram of a plain bearing of a shaft type linear motor showing Embodiment 1 of the present invention. It is sectional drawing of the shaft type linear motor which shows Example 2 of this invention. It is sectional drawing of the shaft type linear motor which shows Example 3 of this invention. It is a block diagram of the plain bearing of the shaft type linear motor which shows Example 4 of this invention. It is sectional drawing of the shaft type linear motor which shows Example 5 of this invention. It is sectional drawing of the shaft type linear motor which shows Example 6 of this invention.

Example 1.
1 is a cross-sectional view of a shaft type linear motor showing Embodiment 1 of the present invention, and FIG. 2 is an exploded perspective view of the shaft type linear motor showing Embodiment 1 of the present invention. 1 and 2, reference numeral 1 denotes a fixed portion of the shaft type linear motor, and 2 denotes a movable portion of the shaft type linear motor, which can be displaced relative to the fixed portion 1 in the axial direction. 31 is a slide bearing that functions as a first bearing and has an L-shaped cross section along the axial direction, 51 is a power supply lead wire, and 11 is a plurality for generating a magnetic flux by causing a current to flow from the power supply lead wire 51. A coil 12, a resin bobbin that insulates the plurality of coils 11, an upper frame 13 serving as a magnetic circuit for the generated magnetic flux, and a cross section 14 along the axial direction, serving as a magnetic circuit for the generated magnetic flux. U-shaped lower frame, 15 is a base for increasing mechanical rigidity, 16 is a bearing that supports a shaft, 17 is a bracket that holds the bearing 16, 18 is a cover that prevents foreign matter from entering, 41 is a position The fixed portion 1 is a slide bearing 31, a coil 11, a bobbin 12, an upper frame 13, a lower frame 14, a base 15, a bearing 16, a bracket 17, a cover 18, and a position detector 41. It is made.

On the other hand, 32 is a sliding member that slides and guides the surface of the slide bearing 31 that functions as a first sliding portion, and 21 is a magnet portion that generates thrust by interaction with the magnetic flux generated by the plurality of coils 11. A plurality of permanent magnets stacked in order to achieve this. 22 is made of a magnetic material or a non-magnetic material, and is arranged between the plurality of permanent magnets 21 so that the N pole and S pole magnetic poles of the plurality of laminated permanent magnets 21 are alternately formed in the axial direction. The spacer 23 is a shaft coupling member, 24 is a shaft (shaft) for transmitting the generated thrust to the machine, and the movable part 2 includes a sliding member 32, a permanent magnet 21, a spacer 22, and a shaft coupling member 23. The movable part 2 is connected to the end of the shaft 24. The other end of the shaft 24 protrudes outside the fixed part 1 and is used for position detection. The central axis of the plurality of permanent magnets 21, the central axis of the spacer 22, and the central axis of the shaft coupling member 23 coincide with the central axis of the shaft 24. The movable part 2 is disposed inside the fixed part 1 and has a structure movable in the Z direction in FIG. The plurality of coils 11 and the plurality of bobbins 12 are arranged concentrically outside the plurality of permanent magnets 21, and the central axes of the plurality of coils 11 and the central axes of the plurality of bobbins 12 are Each coincides with the central axis of the shaft 24.

Reference numeral 42 denotes a scale, 25 denotes a shaft tip of the shaft 24, 26 denotes a scale coupling member, and 52 denotes a position detector lead. The scale 42 is coupled to the shaft distal end portion 25 by the scale coupling member 26, and has a structure that can move according to the movement of the shaft 24. The scale 42 has optical or magnetic position information recorded therein, and the position detector 41 coupled to the fixed portion 1 detects the position of the shaft 24 in the Z direction in FIG. In addition, the position signal is transmitted from the position detector lead wire 52 to the control unit.

The A-A ′ cross section and the B-B ′ cross section are cross sections along the XY plane of the shaft type linear motor shown in FIG. 1.

FIG. 3 is a configuration diagram of a control unit of the shaft type linear motor showing the first embodiment of the present invention. In FIG. 3, 90 is a control unit, and 100 is a shaft type linear motor. 91 is a position control circuit, 92 is a speed control circuit, 93 is a current control circuit, and 99 is a current detector. A control unit 90 is a position control circuit 91, a speed control circuit 92, a current control circuit 93, and a current detector 99. Composed.

Position information detected by the scale 42 and the position detector 41 is fed back to the control unit 90 of the shaft type linear motor 100. The position control circuit 91 performs position control by comparing the position feedback value from the position detector 41 with the command value, and the speed control circuit 92 differentiates the output value from the position control circuit 91 and the position feedback value. The current control circuit 93 can perform thrust control by comparing the output value from the speed control circuit 92 and the current feedback value from the current detector 99, respectively.

FIG. 4 is a structural diagram of a plain bearing of a shaft type linear motor showing Embodiment 1 of the present invention. 61 is a magnetic flux, and 62a and 62b are magnetic attractive forces generated by the influence of the magnetic flux 61 produced by the permanent magnet 21.

The slide bearing 31 is made of resin (non-magnetic material), and has a L-shaped cross section along the axial direction as shown in the A-A ′ cross section of FIG. 4. On the other hand, the sliding member 32 is, for example, an S50C material, and the upper frame 13 and the lower frame 14 are, for example, SPCC materials, all of which are magnetic materials. Here, the sliding member 32 is not concentric with respect to the central axis of the inner space of the coil 11 arranged concentrically with respect to the central axis of the shaft 24, and is installed so as to be eccentric to the sliding bearing 31 side. The As a result, the gap between the sliding member 32 and the upper frame 13 and the gap between the sliding member 32 and the lower frame 14 are each on the side where the slide bearing 31 having an L-shaped cross section is interposed (A in FIG. 4). In the cross section -A ', it does not exist on the left side surface and the bottom surface of the sliding member 32, and has a predetermined distance on the non-intervening side (the right side surface and the top surface of the sliding member 32 in the AA' cross section in FIG. 4). Will exist.

In the AA ′ cross section of FIG. 4, the magnetic flux 61 is magnetic between the upper frame 13 that is a magnetic material and the permanent magnet 21, and between both side surfaces of the U-shaped lower frame 14 that is a magnetic material and the permanent magnet 21. A cross section as a material is formed between the lower surface of the U-shaped lower frame 14 and the permanent magnet 21. Under the influence of the magnetic flux 61 formed, magnetic attractive forces 62a and 62b are generated between the sliding member 32, which is a magnetic material, and the upper frame 13 and the U-shaped lower frame 14, which are magnetic materials. 32 is disposed in such a way that the lower frame 14 has an L-shaped slide bearing 31 on the side where the L-shaped slide bearing 31 is interposed. Therefore, the bias of the sliding member 32 causes the magnetic attraction force 62a to generate a slide having an L-shaped cross section. It acts strongly on the side where the bearing 31 is interposed (the left side surface and the lower surface of the sliding member 32 in the AA ′ cross section of FIG. 4), and the magnetic attractive force 62b is not on the side where the L-shaped slide bearing 31 is not interposed (FIG. In the section AA ′ of FIG. 4, the sliding member 32 has almost no effect on the right side surface and the upper surface.

In the shaft type linear motor configured as described above, the sliding member 32 and the sliding bearing 31 having an L-shaped cross section are always in contact with each other with a constant magnetic attractive force 62a. There is no gap between the slide bearings 31. As a result, there is no rattling or fluctuation caused by the gap that has occurred in the configuration of the conventional shaft type linear motor, and the positioning accuracy of the shaft tip 25 is increased. It becomes possible. In addition, when trying to reduce the gap with the configuration of the conventional shaft type linear motor, it is necessary to process the dimensions of the sliding member 32 and the slide bearing 31 with high accuracy. The linear motor configuration does not require any processing.

As described above, according to the configuration of the shaft type linear motor described in the first embodiment, the positioning accuracy of the shaft tip portion of the shaft type linear motor can be increased. A motor can be applied. For example, it is possible to increase the density of components mounted on an electronic substrate.

Example 2
In the first embodiment of the present invention, the case where only one end portion of the movable portion 2 is used as the slide bearing 31 has been described. However, as shown in FIG. The sliding bearing 31b as the second bearing may be used, and the same effect can be obtained by such a configuration. Corresponding to the sliding bearings 31a, 31b at both ends of the movable part 2, on both sides sliding with the sliding bearings 31a, 31b of the fixed part 1, a sliding member 32a, which is a first sliding part, A sliding member 32b, which is the second sliding portion, is installed.

Example 3
In the first and second embodiments of the present invention, the case where the positional accuracy in the X and Y directions is ensured by using two surfaces of the L-shaped slide bearing 31 is described. In the case of only one direction, for example, only the X direction, as shown in FIG. 6, the slide bearing 35 may be formed in a flat plate shape parallel to the lower surface of the lower frame 14 along the axial direction. In this case, the same effects as those of the first and second embodiments can be obtained.

Example 4
FIG. 7 is a structural diagram of a plain bearing of a shaft type linear motor showing Embodiment 4 of the present invention. Reference numeral 71 denotes a first intermediate member, which is an intermediate member in FIG.

The slide bearing 31 is made of resin (non-magnetic material) and has an L-shaped cross section along the axial direction as shown in the AA ′ cross section of FIG. It is in contact. Further, the intermediate member 71 is a magnetic material such as an SPCC material, for example, and has an L-shaped cross section along the axial direction as shown in the AA ′ cross section of FIG. And is in contact with the lower surface. On the other hand, the sliding member 32 is, for example, an S50C material, and the upper frame 13 and the lower frame 14 are, for example, SPCC materials, all of which are magnetic materials. Here, the sliding member 32 is installed so as to coincide with the central axis of the inner space of the coil 11 arranged concentrically with respect to the central axis of the shaft 24. As a result, the gap between the sliding member 32 and the upper frame 13 and the gap between the sliding member 32 and the lower frame 14 are the sides where the slide bearing 31 and the intermediate member 71 having an L-shaped cross section are interposed ( In the AA ′ cross section of FIG. 7, it does not exist on the left side and lower surface of the sliding member 32, and on the non-intervening side (the right side surface and upper surface of the sliding member 32 in the AA ′ cross section of FIG. 7). It exists with a predetermined distance.

In the AA ′ cross section of FIG. 7, the magnetic flux 61 is magnetic between the upper frame 13 that is a magnetic material and the permanent magnet 21, and between the right side surface of the U-shaped lower frame 14 that is a magnetic material and the permanent magnet 21. A cross section that is a material is formed between the lower surface of the L-shaped intermediate member 71 and the permanent magnet 21, and a cross section that is a magnetic material is formed between the right side surface of the L-shaped intermediate member 71 and the permanent magnet 21. Under the influence of the formed magnetic flux 61, magnetic attractive forces 62a and 62b are formed between the sliding member 32, which is a magnetic material, the upper frame 13, which is a magnetic material, the U-shaped lower frame 14, and the L-shaped intermediate member 71. However, the magnetic attractive force 62a is on the side where the L-shaped cross-section bearing 31 and the intermediate member 71 are interposed (the left side surface and the lower surface of the sliding member 32 in the AA 'cross section in FIG. 7). It acts strongly, and the magnetic attractive force 62b hardly acts on the side where the L-shaped plain bearing 31 and the intermediate member 71 are not interposed (the right side surface and the top surface of the sliding member 32 in the AA ′ cross section in FIG. 7). become.

In the shaft type linear motor configured as described above, the sliding member 32 and the sliding bearing 31 having an L-shaped cross section are always in contact with each other with a constant magnetic attractive force 62a. There is no gap between the slide bearings 31. As a result, there is no rattling or fluctuation caused by the gap that has occurred in the configuration of the conventional shaft type linear motor, and the positioning accuracy of the shaft tip 25 is increased. It becomes possible. In addition, when trying to reduce the gap with the configuration of the conventional shaft type linear motor, it is necessary to process the dimensions of the sliding member 32 and the slide bearing 31 with high accuracy. The linear motor configuration does not require any processing.

As described above, according to the configuration of the shaft-type linear motor described in the fourth embodiment, the positioning accuracy of the shaft tip portion of the shaft-type linear motor can be increased. A motor can be applied. For example, it is possible to increase the density of components mounted on an electronic substrate.

Example 5 FIG.
In the fourth embodiment of the present invention, the case where the intermediate member 71 is applied only to one end of the movable portion 2 has been described. However, as shown in FIG. 8, the intermediate member that is the first intermediate member at both ends of the movable portion 2. 71a and the intermediate member 71b which is a 2nd intermediate member may be applied, and the same effect can be acquired also by such a structure.

Example 6
In the fourth embodiment and the fifth embodiment of the present invention, the case where the positional accuracy in the X and Y directions is ensured by using two surfaces of the L-shaped intermediate member 71 is described. In the case of only one direction, for example, only the X direction, as shown in FIG. 9, the intermediate member 75 may be formed in a flat plate shape parallel to the lower surface of the lower frame 14 along the axial direction. In this case, the same effects as those of the fourth and fifth embodiments can be obtained.

In the configuration of the shaft type linear motor described in the fourth to sixth embodiments, the case where the intermediate members 71, 71a, 71b and the lower frame 14 are handled as separate members has been described. , 71a, 71b, the same effect can be obtained in the configuration of the new lower frame 14.

In the first to sixth embodiments of the present invention, the case where the present invention is applied to a shaft type linear motor has been described. However, the present invention is not limited to this, and the same effect can be obtained when applied to other linear motors. Can be obtained.

DESCRIPTION OF SYMBOLS 1 Fixed part, 2 Movable part, 11 Coil, 12 Bobbin, 13 Upper frame, 14 Lower frame, 15 Base, 16 Bearing, 17 Bracket, 18 Cover, 21 Permanent magnet, 22 Spacer, 23 Shaft coupling member, 24 Shaft, 25 Shaft tip, 26 Scale coupling member, 31 Slide bearing, 31a Slide bearing, 31b Slide bearing, 32 Slide member, 32a Slide member, 32b Slide member, 35 Slide bearing, 41 Position detector, 42 Scale, 51 Power supply Lead wire, 52 position detector lead wire, 61 magnetic flux, 62a magnetic attractive force, 62b magnetic attractive force, 71 intermediate member, 71a intermediate member, 71b intermediate member, 75 intermediate member, 90, control unit, 91 position control circuit, 92 Speed control circuit, 93 Current control circuit, 99 Current detector, 00 shaft-type linear motor.

Claims (12)

A linear motor having a fixed part and a movable part located inside the fixed part and provided so as to be relatively displaceable in the axial direction with respect to the fixed part,
The movable part is composed of a magnet part composed of a plurality of permanent magnets stacked in the axial direction, and a magnetic material disposed at one tip of the magnet part and slidingly guiding the inside of the fixed part in the axial direction. A first sliding part,
The fixed portion is provided inside the fixed portion with a first bearing made of a non-magnetic material that is in contact with the inner surface of the fixed portion that slidably supports the first sliding portion. A plurality of coils that generate magnetic flux and act on the magnet portion to relatively displace the movable portion;
The first sliding portion is arranged such that the central axis of the first sliding portion is eccentric to the first bearing side from the central axis of the inner space formed by the coil, and abuts on the first bearing. The linear motor is characterized in that the magnetic attractive force from the permanent magnet acts in an eccentric direction. 2. The linear motor according to claim 1, wherein an inner cross section of the fixed portion is rectangular, the first sliding portion is rectangular, and a cross section of the first bearing is L-shaped. The linear motor according to claim 2, wherein the first bearing has a flat cross section. A linear motor having a fixed part and a movable part located inside the fixed part and provided so as to be relatively displaceable in the axial direction with respect to the fixed part,
The movable part is composed of a magnet part composed of a plurality of permanent magnets stacked in the axial direction, and a magnetic material that is disposed at both ends of the magnet part and slides and guides the inside of the fixed part in the axial direction. Comprising first and second sliding portions;
The fixed portion is provided inside the fixed portion, and first and second bearings made of a nonmagnetic material abutted on the inner surface of the fixed portion that slidably supports the first and second sliding portions. A plurality of coils that generate magnetic flux in their own internal space and act on the magnet part to relatively displace the movable part,
The first and second sliding portions are arranged such that the first and second sliding portion central axes are eccentric from the cross-sectional central axis of the inner space formed by the coil toward the first and second bearings. A linear motor in which the magnetic attraction force from the permanent magnet acts in an eccentric direction by contacting the first and second bearings. 5. An inner cross section of the fixed portion is rectangular, the first and second sliding portions are rectangular, and a cross section of the first and second bearings is L-shaped. The linear motor described in 1. The linear motor according to claim 5, wherein the first and second bearings have a flat cross section. A linear motor having a fixed part and a movable part located inside the fixed part and provided so as to be relatively displaceable in the axial direction with respect to the fixed part,
The movable part is composed of a magnet part composed of a plurality of permanent magnets stacked in the axial direction, and a magnetic material disposed at one tip of the magnet part and slidingly guiding the inside of the fixed part in the axial direction. A first sliding part,
The fixed portion includes a first intermediate member made of a magnetic material fixed to the inner surface of the fixed portion in a non-rotation symmetric manner with respect to the fixed portion central axis, and the first sliding portion slidably supported. A first bearing made of a non-magnetic material that is in contact with the first intermediate member, and a relative displacement of the movable part that is provided inside the fixed part, generates a magnetic flux in its inner space, and acts on the magnet part. A plurality of coils to be
The linear motor according to claim 1, wherein the first sliding portion abuts on the first bearing so that a magnetic attractive force from the permanent magnet acts on the first intermediate member side. The inner cross section of the fixed portion is rectangular, the first sliding portion is rectangular, and the first bearing and the first intermediate member have L-shaped cross sections. The linear motor described in 1. The linear motor according to claim 8, wherein a cross section of the first bearing and the first intermediate member is a flat plate shape. A linear motor having a fixed part and a movable part located inside the fixed part and provided so as to be relatively displaceable in the axial direction with respect to the fixed part,
The movable part is composed of a magnet part composed of a plurality of permanent magnets stacked in the axial direction, and a magnetic material that is disposed at both ends of the magnet part and slides and guides the inside of the fixed part in the axial direction. Comprising first and second sliding portions;
The fixed portion slides between the first and second intermediate members made of a magnetic material fixed to the inner surface of the fixed portion in a non-rotation symmetric manner with respect to the central axis of the fixed portion, and the first and second sliding portions. First and second bearings made of a non-magnetic material abutting against the first and second intermediate members that are movably supported, and provided inside the fixed portion, generate magnetic flux in its own internal space, A plurality of coils that act on the magnet portion to relatively displace the movable portion;
The first and second sliding portions are in contact with the first and second bearings so that a magnetic attraction force from the permanent magnet acts on the first and second intermediate members. motor. An inner cross section of the fixed portion is rectangular, the first and second sliding portions are rectangular, and a cross section of the first and second bearings and the first and second intermediate members are L-shaped. The linear motor according to claim 10, wherein the linear motor is provided. 12. The linear motor according to claim 11, wherein the first and second bearings and the first and second intermediate members have a flat cross section.

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