JPH06335230A - Permanent magnet type linear synchronous motor - Google Patents

Abstract

PURPOSE:To enable a movable element to be set to a constant phase position on a magnetic pole automatically by stopping the conduction to a coil. CONSTITUTION:In this linear synchronous motor, a movable element 7 is automatically set to a constant phase position on a magnetic pole due to the magnetic force of a small magnet 8 provided at the movable element after the supply of the drive current to an armature coil 6 stops.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a permanent magnet type linear synchronous motor in which a permanent magnet and an armature coil move relative to each other.

[0002]

2. Description of the Related Art Conventionally, a plurality of permanent magnets arranged in a yoke via a magnetic gap so that adjacent magnetic poles are different from each other and the polarities of different magnetic poles are opposed to each other, and a plurality of permanent magnets inside the magnetic gap. A linear motor is known which has an armature coil provided in the armature coil, and causes a permanent magnet and the armature coil to move relative to each other by supplying a drive current to the armature coil. Such linear motors include a type in which a permanent magnet is fixed and the armature coil is moved (moving coil type), and a type in which the armature coil is fixed and a permanent magnet is moved (movable magnet type). There is. Then, conventionally, the control of the linear motor has been performed as follows. A Hall element is provided in each coil, and the Hall element detects a magnetic pole and sends a magnetic pole detection signal to the drive unit. On the other hand, the linear motor is provided with a position detector (encoder) and sends a position signal from this position detector to the main control unit. The main control unit generates a thrust command value (torque command value) based on this position signal and the target movement amount and sends it to the drive unit. The drive unit energizes and switches the coil based on the magnetic pole detection signal and the thrust command value. When the target movement amount is finally reached, the coil is de-energized and the mover stops. As described above, conventionally, the position detector (encoder) is used to output the thrust command value, and the hall element is used to switch the coil. As a technique related to this, for example, Japanese Patent Laid-Open No. 63-
There are 103653 and so on.

[0003]

In the above conventional linear motor, the mover must always detect the magnetic pole on the stator side. A Hall element is required to determine the magnetic pole on the mover side. Then, it is necessary to flow a drive current to the mover based on the magnetic pole detection signal of the Hall element.

Therefore, the present invention has been made in view of the above-mentioned problems of the prior art, and its object is to make the mover automatically move to a constant phase position on the magnetic pole when the coil is de-energized. To be set.

[0005]

In order to achieve the above object, in the permanent magnet type linear synchronous motor of the present invention, adjacent magnetic poles are different from each other, and polarities of different magnetic poles are opposed to each other. The permanent magnet and the armature coil are provided with a plurality of permanent magnets arranged in the yoke via the magnetic gap and an armature coil provided in the magnetic gap, and by supplying a drive current to the armature coil. In a linear motor in which the and are relatively moved, a small magnet is arranged at a predetermined position of the armature coil, and after the supply of the drive current to the armature coil is stopped, the magnetic force of the small magnet causes the mover to move to the magnetic pole. It is configured to be set at the upper constant phase position.

[0006]

In the present invention, since the small magnet is provided at the predetermined position of the armature coil, if the supply of the drive current to the armature coil is stopped, then the magnetic force of the small magnet causes the mover to move on the magnetic pole. It is automatically set to a fixed phase position. Therefore, it is not necessary to determine the magnetic pole, and the Hall element can be omitted. Along with this, the circuit and wiring for switching the coil based on the signal of the Hall element becomes unnecessary,
The control circuit itself is also simplified.

[0007]

Embodiments of the present invention will be described with reference to the drawings. First, FIG. 2 shows a cross section of a main part of a permanent magnet type linear synchronous motor of the present invention. A center yoke 2 and a side yoke 3 are fixed on the base 1. Inside the center yoke 2 and the side yoke 3, a plurality of permanent magnets 4 are arranged. The permanent magnet 4 is arranged in a direction perpendicular to the plane of the drawing. Opposing permanent magnets 4a and 4b are arranged with a constant magnetic gap 5 interposed therebetween. An armature coil 6 is arranged in this magnetic gap 5.

The armature coil 6 is composed of a multi-phase coil, and by switching the current flowing through each coil, the armature coil 6 can move in a fixed direction with a constant thrust. As the armature coil 6 moves in this way, the mover 7 having the armature coil moves. The linear synchronous motor of FIG. 2 is of a type having two thrust generating portions, but the present invention is not limited to this, and is applicable to, for example, a linear synchronous motor of a type having only one thrust generating portion. is there.

Next, FIG. 1 shows an outline of a control system for a linear synchronous motor. Center yoke 2 and side yoke 3
Inside, a plurality of permanent magnets 4 are arranged such that the polarities of adjacent magnetic poles are different from each other. Further, the magnetic poles of the facing permanent magnets 4a and 4b are different from each other. An armature coil 6 is arranged in the magnetic gap 5 between the opposing permanent magnets 4a and 4b. And
A small magnet 8 is provided at a predetermined position of the armature coil 6. As the small magnet 8, a magnet that generates a force larger than static friction is used.

If the magnetic force of the small magnet 8 is too large, the thrust will be reduced. Therefore, the magnetic force of the small magnet 8 is preferably about 5% of the magnetic flux density of the magnetic gap 5. With such a magnetic force, an increase in thrust ripple can be suppressed as much as possible. Further, the linear synchronous motor A is provided with position detecting means B for detecting the position of the armature coil 6. The position detecting means B is composed of a read head 9 arranged at a predetermined position of the armature coil 6 and a scale 10 fixedly arranged. The scale 10 has opaque graduations on a transparent glass at regular intervals, and the graduation is optically read by the reading head 9.

The position detecting means B is connected to the control section C. The control unit C has a calculation unit 11 and a ring counter 12. The calculation unit 11 inputs a movement amount pulse signal 17 from the reading head 9 and a command input (target movement amount pulse).
A thrust command signal 14 is generated based on Also,
The ring counter 12 counts the movement amount pulse signal 17 from the reading head 9 and generates a switching signal 15 each time the reference pulse number is reached. The control section C is connected to a drive section D having a power amplifier. This drive unit D
It is connected to the armature coil 6 which is a mover of the linear motor A, and a predetermined drive current is supplied to the armature coil 6 based on the thrust command signal 14 from the arithmetic unit 11 and the switching signal 15 from the ring counter 12 is supplied. Based on the armature coil 6
Switch the current of.

Finally, the operation of the present invention will be described. First,
The armature coil 6, which is a mover, is set at a constant phase position on the magnetic pole. This is because if the supply of the drive current to the armature coil 6 is stopped, the small magnet 8 provided in the armature coil 6
By the magnetic force of, the armature coil 6 is automatically set at a constant phase position on the magnetic pole. That is, when the energization of the armature coil 6 is stopped, an attractive force acts between the predetermined permanent magnets 40 arranged on the yokes 2 and 3 and the small magnets 8, and the armature coil 6 automatically moves. It is set at a constant phase position on the magnetic pole.

Next, a command input 13 indicating a target movement amount (target movement pulse number) of the armature coil 6 is input to the control section C in advance. Then, when a predetermined drive current is supplied to the armature coil 6, a thrust is generated between the permanent magnet 4 and the armature coil 6, and the armature coil 6 moves in a fixed direction. Then, the position detecting means B sends the movement amount pulse signal 17 of the armature coil 6 to the control section C. Computing unit 1
1 generates a thrust command signal 14 based on the moving amount pulse signal 17 and the target moving amount 13 and sends it to the drive unit D. The drive unit D supplies a drive current based on the thrust command signal 14 to the armature coil 6 of the linear synchronous motor A.

The ring counter 12 counts the moving amount pulse signal 17 and generates a switching signal 15 each time the reference pulse number is reached and sends it to the drive unit D. The drive unit D switches the current of the armature coil 6 based on the switching signal 15. As a result, a thrust in a fixed direction is generated and the armature coil 6 moves in the fixed direction. When the calculation unit 11 detects that the armature coil 6 has moved by the target movement amount, the calculation unit 11 sends a thrust command signal 14 to that effect to the drive unit D. The drive unit D stops the supply of the drive current to the armature coil 6 based on the thrust command signal 14.

After that, the armature coil 6 is again set to the constant phase position on the magnetic pole by the magnetic force of the small magnet 8 provided on the armature coil 6 which is the mover. As described above, in this embodiment, since the magnetic pole counter is initialized by the small magnet 8 provided in the armature coil 6, the Hall element is not required, and the control circuit can be simplified accordingly. In the above embodiment, the permanent magnet 4 is fixed and the armature coil 6 is moved, but the present invention is not limited to this, and the armature coil 6 is fixed and the permanent magnet 4 is moved. It is also applicable to the linear synchronous motor of.

[0016]

According to the present invention, since the mover is set to the constant phase position on the magnetic pole by utilizing the small magnet provided in the armature coil, it is not necessary to judge the magnetic pole. The Hall element can be omitted. Along with this, a circuit for switching the coil based on the signal from the Hall element is not needed, and the control circuit itself can be simplified.

[Brief description of drawings]

FIG. 1 is a diagram showing an outline of a control system of a permanent magnet type linear synchronous motor.

FIG. 2 is a sectional view of a main part of a permanent magnet type linear synchronous motor.

[Explanation of symbols]

 A linear synchronous motor B position detection means C control unit D drive unit 4 permanent magnet 5 magnetic gap 6 armature coil 7 mover 8 small magnet 9 read head 10 scale

Claims (1)

[Claims] 1. A plurality of permanent magnets arranged in a yoke via a magnetic gap so that adjacent magnetic poles are different from each other and the polarities of the different magnetic poles face each other, and the permanent magnets are provided in the magnetic gap. In a linear motor having a fixed armature coil and a drive current flowing through the armature coil, the permanent magnet and the armature coil are moved relatively to each other. A permanent magnet linear synchronization characterized in that a magnet is arranged, and after the supply of the drive current to the armature coil is stopped, the mover is set to a constant phase position on the magnetic pole by the magnetic force of this small magnet. motor.