JP3488845B2 - Linear motor - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a linear motor. More specifically, the present invention relates to a linear motor suitable for use in FA (factory automation).

[0002]

2. Description of the Related Art In a conventional linear motor, a mover 101 is moved along two linear guides 103 provided on a stator 102, as shown in FIG.
The facing surface 104 of the magnetic circuit that generates thrust is disposed between the two linear guides 103. That is, the facing surface 104 of the magnetic circuit is one surface and is formed between the two linear guides. Further, various sensors 105 such as a linear encoder that detects the position of the mover 101 are attached to an external surface position such as a side surface of the linear motor.

[0003]

However, in the above-mentioned linear motor, since the facing surface 104 of the magnetic circuit is formed between the two linear guides 103, the stator 102 is not formed.
The magnetic attraction force generated between the movable element 101 and the movable element 101 acts as a force that deforms the stator 102 and the movable element 101 as indicated by a two-dot chain line in FIG. For this reason, it is necessary to make the stator 102 and the mover 101 thick and to reinforce them to ensure rigidity, which hinders the reduction in size and weight of the linear motor.
Further, since the facing surface 104 of the magnetic circuit is one, it is difficult to obtain high thrust.

An object of the present invention is to provide a linear motor capable of canceling the magnetic attraction force generated between the stator and the mover and increasing the number of facing surfaces of the magnetic circuit.

[0005]

In order to achieve the above object, a linear motor according to a first aspect of the present invention is arranged on a frame having a U-shaped cross section and a straight longitudinal direction, and two walls in the longitudinal direction of the frame. Armor having a fixed core, a coil facing the core, an armature-side block in which an armature and a magnet are integrally provided, and a linear guard arranged inside the frame.
A id, the linear guide rail is fixed to the frame, by fixing the linear guide of the slide block on the armature side block, relatively straight one side against the other side of the frame and an armature-side block While making it movable,
Fix the linear scale of the linear encoder to the rail,
A linear block is provided with a sensor having a gap and facing each other on a slide block.

Therefore, the armature side block is arranged inside the frame, and the opposing surfaces of the magnetic circuit are formed at two positions sandwiching the armature side block. Therefore, the thrust is generated at two places, and the magnetic attraction force generated on the facing surface of the magnetic circuit can be canceled. Further, since the armature block is arranged inside the frame, the linear scale of the linear encoder and the sensor are also arranged inside the frame. The linear motor relatively moves the frame and the armature side block along the linear guide by the thrust generated on the opposing surfaces of the magnetic circuits at two locations.

According to the linear motor of the second aspect, the armature-side block is a mover, the frame is a stator, and the mover is capable of linearly moving with respect to the frame. Therefore, by installing the frame on, for example, a factory line, the armature-side block can be moved from a predetermined position to a predetermined position along the linear guide.

In the linear motor according to the third aspect, the linear scale is a magnetic linear scale, and the magnetic sensors are opposed to each other. Therefore, the relative position between the armature-side block and the frame can be magnetically detected.

According to the linear motor of the fourth aspect, a magnetic resistance element is used for the magnetic sensor. Reliability is improved by using a magnetoresistive element that has been used as a magnetic sensor and has a large technical accumulation.

A linear motor according to a fifth aspect is
A sensor reflection plate is fixed to the side surface of the slide block, and a plurality of position detection sensors are arranged at positions facing the sensor reflection plate of the frame. In order to improve the accuracy of position detection by the linear scale, it is effective to adopt the vernier method. The vernier method has the same structure as a large number of short linear scales are connected and the position can be detected in one of the linear scales. Since it is not possible to detect together with which position the linear scale is located, it is necessary to detect this by another means. In the linear motor according to claim 5, of the plurality of position detection sensors, based on the information indicating which position detection sensor detects the sensor reflector, the linear scale at which the currently detected position is. About the position.

Further, the linear motor according to claim 6 is
A reflection type photoelectric sensor is used for the position detection sensor. Reliability is improved by using a reflective photoelectric sensor, which has been used a lot and has a large technical accumulation as a position detection sensor.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The structure of the present invention will be described below in detail based on the best mode shown in the drawings.

1 to 5 show an example of an embodiment of a linear motor to which the present invention is applied. This linear motor is an armature having a frame 1 having a U-shaped cross section and a straight longitudinal direction, a core 2 arranged on two vertical walls 1 a of the frame 1, and a coil 3 facing the core 2. 4 and armature 4
And a magnet 5 are integrally provided on the armature side block 6, the rail 7 of the linear guide 9 is fixed to the frame 1, the slide block 8 of the linear guide 9 is fixed to the armature side block 6, and the frame is fixed. 1 and armature side block 6
And one side of the linear scale relative to the other side, and linear scale 11 of the linear encoder 10
Is fixed to the rail 7, and the sensor 12 facing the linear scale 11 with a gap is disposed on the slide block 8.

In this embodiment, the armature block 6 is a mover, the frame 1 is a stator, and the frame 1 is a stator.
On the other hand, the mover can move straight ahead. However,
Of course, the relationship between the armature-side block 6 and the mover may be reversed so that the armature-side block 6 serves as the stator and the frame 1 serves as the mover.

Side plates 13 are attached to both ends of the frame 1 as a stator in the longitudinal direction, and linear guides 9 are installed between the side plates 13. The upper surface of the armature-side block 6 is a table 14.

The armature side block 6 is arranged inside the frame 1, and the frame-shaped block 2 having a U-shaped cross section is provided.
Since the cores 2 are arranged on the one wall 1a, the facing surfaces 15 of the magnetic circuit are formed on both sides of the armature block 6.

The linear scale 11 is, for example, a magnetic linear scale, and is embedded in the rail 7 of the linear guide 9. A magnetic sensor 12 is arranged to face the linear scale 11 with a predetermined gap therebetween. That is, the magnetic sensor 12 and the linear scale 11 are
It is arranged inside the frame 1 having a U-shaped cross section. As the magnetic sensor 12, for example, a magnetoresistive element is used. However, it goes without saying that it is not limited to the magnetoresistive element. The linear scale 11 is magnetized at predetermined intervals, and the magnetic sensor 12 counts the magnetized portion, so that the position of the armature-side block 6 can be detected. In this embodiment, the magnetic sensor 12 is attached to the bottom surface of the block 16 fixed to one end surface of the armature-side block 6 so as to be arranged on the slide block 8 side.

The linear scale 11 is of a vernier type, for example, and is provided with a position detection sensor 17 for detecting the position of the armature side block 6 for each length of the vernier. FIG. 6 conceptually shows the relationship between the linear scale 11 and the position detection sensor 17. A sensor reflection plate 18 is fixed to a side surface of the slide block 8, and a plurality of position detection sensors 17 are provided at positions of the frame 1 facing the sensor reflection plate 18.
Is provided. The sensor reflection plate 18 and the position detection sensor 17 are arranged inside the frame 1 having a U-shaped cross section. The position detection sensor 17 is, for example, a reflective photoelectric sensor, and is provided for each vernier 11 a of the linear scale 11. Sensor reflector 18 and magnetic sensor 1
Since 2 moves integrally with the armature block 6, the position information detected by the magnetic sensor 12 by the position detection sensor 17 and the sensor reflection plate 18 is the vernier 11a.
Can be detected. When the linear scale 11 of the linear encoder 10 is of the vernier type, the resolution of the linear encoder 10 can be increased.

When a current is passed through the coil 3 of the armature 4, thrust is generated between the core 2 and the armature 4, and the armature side block 6 moves along the linear guide 9 with respect to the frame 1. Since the facing surface 15 of the magnetic circuit that generates the thrust is formed at two positions sandwiching the armature-side block 6, the magnetic attraction force generated in the facing surface 15 of the magnetic circuit can be canceled. Therefore, the required rigidity can be obtained without making the frame 1 and the like thick, and the linear motor can be made smaller and lighter. Further, since it is possible to prevent the frame 1 and the like from being deformed due to the magnetic attraction force, it is possible to prevent a change in the gap between the linear scale 11 and the magnetic sensor 12, and it is possible to improve the detection accuracy. Further, as compared with the conventional linear motor in which the facing surface 15 of the magnetic circuit is one, since the facing surface 15 of the magnetic circuit is formed at two places, it is possible to obtain a limit thrust about twice as much.

The position of the armature side block 6 is detected by the linear scale 11, the magnetic sensor 12, the position detection sensor 17 and the sensor reflector plate 18. Since these are arranged inside the frame 1, the structure is not easily affected by the surroundings of the linear motor. Further, since the linear scale 11 is attached to the center of thrust of the linear motor, the linear scale 11 is driven when the linear motor is driven.
The gap fluctuation between the magnetic sensor 12 and the magnetic sensor 12 can be suppressed, and the gap management is easy. In addition, the linear scale 11 and the magnetic sensor 12 can be arranged at a position that is not easily affected by the leakage magnetic flux of the linear motor body. For these reasons, highly accurate position detection becomes possible.

The above-mentioned embodiment is an example of a preferred embodiment of the present invention, but the present invention is not limited to this, and various modifications can be made without departing from the gist of the present invention. For example, although the linear scale 11 of the linear encoder 10 is embedded in the rail 7 of the linear guide 9 in the above description, it may be attached onto the rail 7 as shown in FIG. 7.

Although the magnetic encoder is used as the linear encoder 10, an optical linear encoder or the like may be used.

Further, although the reflection type photoelectric sensor is used as the position detecting sensor 17, a transmission type photoelectric sensor or a magnetic proximity sensor may be used, for example.

Further, a chuck, a jig, an arm or the like may be attached to the armature side block 6. In this case, the side plate 13 may be removed from the frame 1 in order to avoid interference with the chuck, the jig, the arm and the like. By removing the side plate 13, the rail 7 of the linear guide 9 and the table 1
An object to be moved such as a work can be placed in the space above 4.

[0025]

As described above, in the linear motor according to the first aspect, a frame having a U-shaped cross section and a straight longitudinal direction, a core arranged on two vertical walls of the frame, and a core An armature having a coil facing each other, an armature-side block integrally provided with the armature and a magnet, and a frame.
With a linear guide arranged inside the arm, the rail of the linear guide is fixed to the frame, the slide block of the linear guide is fixed to the armature side block, and the frame and the armature side block are fixed on one side. Since the linear scale of the linear encoder is fixed to the rail and the sensors facing each other with a gap in the linear scale are arranged on the slide block, it is possible to move straight relative to the other side. It is possible to dispose the linear guide and the armature side block at the same time, and to form the facing surface of the magnetic circuit at two places sandwiching the armature side block. For this reason, the magnetic attraction forces generated on the opposing surfaces of the magnetic circuit can be canceled each other, and the magnetic circuit is in a balanced state, and the rigidity of the frame etc. is not required to be very large. Can be converted. In addition, since the surface of the linear motor that outputs thrust (opposing surface of the magnetic circuit) can be formed at two locations, it is possible to obtain a limit thrust that is about twice as large as that of a surface having one opposing surface of the magnetic circuit. . Further, since the magnetic circuit of the linear motor and the linear encoder can be housed inside the U-shape of the frame, these can be protected against mechanical disturbance.

Further, since the linear guide and the armature side block are arranged inside the frame, the linear encoder can be attached to the thrust center of the linear motor.
Therefore, the gap between the linear scale and the sensor does not easily change when the linear motor is driven, and the gap management is easy. Further, the linear encoder can be arranged at a position where it is unlikely to be affected by the leakage magnetic flux of the linear motor body. For these reasons, highly accurate position detection becomes possible.

In the linear motor according to the second aspect,
The armature block is a mover, the frame is a stator, and the mover can move straight with respect to the frame.By installing the frame on a factory line, for example, the armature block can be moved along the linear guide in a predetermined direction. It can be moved from a position to a predetermined position.

According to the linear motor of the third aspect,
Since the linear scale is a magnetic linear scale and the magnetic sensors are opposed to each other, the relative position of the armature-side block and the frame can be magnetically detected. In this case, it is preferable to use a magnetoresistive element for the magnetic sensor as in the linear motor of the fourth aspect. The durability and reliability of the linear encoder can be improved by using a magnetoresistive element that has been used a lot and has a large technical accumulation.

According to the linear motor of the fifth aspect,
The sensor reflector is fixed to the side surface of the slide block, and multiple position detection sensors are arranged at the positions facing the sensor reflector of the frame, so it is possible to use the vernier method as a linear encoder, and it is highly accurate. It becomes possible to detect the position of. In this case, it is preferable to use a reflective photoelectric sensor as the position detection sensor as in the linear motor of the sixth aspect. By using a reflective photoelectric sensor, which has a lot of experience in use as a position detection sensor and has a lot of technical accumulation,
The durability and reliability of the position detection sensor can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view taken along the line II of FIG. 2, showing an example of an embodiment of a linear motor of the present invention.

FIG. 2 is a plan view of the linear motor.

3 is a cross-sectional view of the linear motor taken along the line III-III in FIG.

4 is a cross-sectional view of the linear motor taken along the line IV-IV in FIG.

5 is a cross-sectional view of the linear motor taken along the line VV of FIG.

FIG. 6 is a conceptual diagram showing a relationship between a linear scale and a position detection sensor.

FIG. 7 shows another embodiment of the linear motor of the present invention,
It is sectional drawing in the same position as FIG.

FIG. 8 is a conceptual diagram of a conventional linear motor.

[Explanation of symbols]

1 frame 1a wall 2 cores 3 coils 4 armature 5 magnets 6 Armature side block 7 rails 8 slide blocks 9 Linear guide 10 linear encoder 11 linear scale 12 Magnetic sensor 17 Position detection sensor 18 Sensor reflector

Continuation of the front page (56) Reference JP-A-8-251904 (JP, A) JP-A-1-318538 (JP, A) JP-A 64-50750 (JP, A) JP-A-60-226762 (JP , A) JP-A-11-154019 (JP, A) JP-A-7-327352 (JP, A) Actual Kaihei 2-97863 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB) Name) H02K 41/00

Claims (6)

(57) [Claims] 1. A frame having a U-shaped cross section and a linear longitudinal direction, a core arranged on two vertical walls of the frame, an armature having a coil facing the core, an armature and a magnet. an armature-side block provided integrally bets, deflection
With a linear guide arranged inside the arm, the rail of the linear guide is fixed to the frame, the slide block of the linear guide is fixed to the armature side block, and the frame and the armature side block are fixed on one side. The linear scale is relatively movable with respect to the other side, the linear scale of the linear encoder is fixed to the rail, and the sensor having a gap in the linear scale and facing each other is arranged on the slide block. Linear motor. 2. The linear motor according to claim 1, wherein the armature-side block is a mover, the frame is a stator, and the mover can move linearly with respect to the frame. 3. The linear motor according to claim 1, wherein the linear scale is a magnetic linear scale, and the magnetic sensors are opposed to each other. 4. The linear motor according to claim 3, wherein a magnetic resistance element is used for the magnetic sensor. 5. The sensor reflection plate is fixed to a side surface of the slide block, and a plurality of position detection sensors are arranged at positions facing the sensor reflection plate of the frame. The linear motor described in Crab. 6. The linear motor according to claim 5, wherein a reflective photoelectric sensor is used as the position detection sensor.