JPS62114462A - Linear motor - Google Patents

Abstract

PURPOSE:To unnecessitate sensor bias magnet, by utilizing leakage flux generated due to a magnet in the space of a mover core and a stator core confronted with each other and on the periphery, as the bias magnetic flux of a magnetic sensor. CONSTITUTION:A linear motor is organized with a stator 1, a mover core 2, a magnet 3, wheels 4, and the like. Then, a magnetic sensor 8 is fixed on the mover core 2 via a sensor-fitting bed 6. Then, due to the magnet 3, magnetic flux is formed between the right and left mover cores 2 and the stator 1, and passes a magnetic pole tooth group 2-1 as main magnetic flux F, but by a part of the flux, leakage flux F2 is formed in the space of the mover core 2 and the stator 1 confronted with each other and on the periphery. By applying the leakage flux F2 as the bias magnetic flux of the magnetic sensor 8, sensor signal can be obtained without using a bias magnet.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a linear motor that can be applied to linear positioning mechanisms of typewriters, printers, etc., and linear constant speed feeding mechanisms of optical systems of copying machines, image scanners, etc. It is related to.

BACKGROUND OF THE INVENTION In recent years, linear stepping motors have become widely used in office machines, but due to open-loop control, they are open during the tax adjustment period and cannot be used at high speeds. Therefore, attempts are being made to increase the speed of the motor by detecting the position of the motor and performing closed-loop control.

An example of the conventional linear motor mentioned above will be described below with reference to the drawings.

4 and 5 show the structure of a conventional linear motor. In FIGS. 4 and 5, 1 is a stator. Reference numeral 1-1 denotes a magnetic column, which is formed at a constant pitch in the longitudinal direction of the stator 1, and the phase difference between the two left and right columns is 1. /2
It's a bitch. 2 is Muuuakoa, which is divided into left and right sides. 2-1 is a magnetic pole tooth group, which has the same pitch as the magnetic pole tooth row 1-1, and faces the magnetic pole tooth row 1-1 through a certain gap, and is spaced at 1/3 pitch from each other. Has a phase difference. Groups of magnetic pole teeth of the same phase are arranged on the left and right sides of the Mova core 2, and there are a total of six groups of magnetic pole teeth. 3 is a magnet, which excites the magnetic pole tooth group 2-1. 2-2 is a coil that excites the left and right magnetic pole tooth groups 2-1 of the Mova core 2 in the same phase, and the magnetic flux formed by the magnet 3 is strengthened by the right (left) magnetic pole tooth group, so that the left (right) magnetic pole IfIn has three phases so that they weaken each other.

Reference numeral 4 denotes wheels, which allow the mover core 2 to run smoothly on the stator 1. Reference numeral 5 denotes an axle, which holds the wheels 4 and supports the mover core 2 so that it does not stick to the stator 1. 8 is a magnetic sensor that detects the unevenness of the magnetic pole tooth row 1-1 and converts it into an electric signal. 10 is a sensor bias magnet, which biases the magnetic sensor 8. 9 is a sensor holder made of non-magnetic material;
The magnetic sensor 8 faces the magnetic pole tooth row 1-1 with a constant gap therebetween, and also has a constant phase with respect to the magnetic pole tooth group 2-1. It holds a magnetic sensor 8.

7 is a screw, and the Ren' holder 9 is moved to Move Ania 2.
Fixed to.

The operation of the linear motor configured as above will be described below.

First, the magnetic sensor 8 is given a bias magnetic flux F1 as shown in FIG. S by the sensor bias magnet 10+' knee, but if the mover core 2 moves,
The bias magnetic flux F1 changes according to the unevenness of the surface. However, as shown in FIG. 6, the electrical resistance of the magnetic sensor 8 changes in response to changes in the external magnetic field, so the magnetic sensor 8 converts the unevenness of the magnetic pole tooth row 1-1 into an electrical signal as the mover core 2 moves. It becomes possible to convert. At this time, magnetic sensor 8
If three sensing sections having a phase difference of 1/3 pitch are provided within the sensor, three-phase electrical signals can be obtained. Generally, the electric signal is a three-phase sine wave signal, but depending on how the sensor bias magnetic flux F1 is applied, a distorted wave close to a square wave can also be obtained.

On the other hand, the generation of thrust is between the magnetic pole teeth rr12-1 and the magnetic pole m row 1.
It utilizes the reluctance change depending on the relative position of −1, and is generally applied to hybrid stepping motors and the like. That is, by exciting the 3-phase coil 2-1 wound around the magnetic pole tooth group 2-1 facing the magnetic pole tooth row 1-1, the magnetic pole tooth group 1-1 and the magnetic pole tooth group 2-1 are magnetized. A suction force acts, and its forward direction component acts as a thrust force. Therefore, by switching the excitation of the three-phase coil 2-1 in a timely manner, the mover core 2 moves forward or backward. At this time, the timing of excitation is set to 3 of the above-mentioned sensor 8.
If a phase electric signal (hereinafter referred to as a sensor signal) is applied, a brushless motor is constructed. (Unexamined Japanese Patent Publication No. 58-
198162) Problems to be Solved by the Invention However, in the above configuration, the sensor bias magnet 10 is required, and the shape of the sensor holder 9 also becomes large, so it is necessary to provide it outside the mover core 2. The problem was that the effective stroke of the motor was shortened by that amount.

In addition, since the number of parts increases, the mounting pitch accuracy of Muu°Acore 2 and magnetic sensor 8, magnetic sensor 8 and magnetic pole tooth row 1,
-1 and the mounting gap accuracy was poor.

In view of the above problems, the present invention provides a linear motor that does not require a sensor bias magnet and has a long effective stroke of the mover core.

Means for Solving the Problems In order to solve the above problems (two), the linear motor of the present invention includes a stator having a row of magnetic pole teeth formed at a constant pitch in the operator direction, and a stator having a stator magnetic pole arranged in a matrix. Provided between a mover core having a plurality of m groups of magnetic poles in which the phases of the m groups of magnetic poles facing each other at the same pitch and with a certain gap are shifted at a certain ratio, and the 11 teeth of the Tj1 pole of the mover core. and a magnetic sensor placed in a space formed by the stator and Moore core facing each other.

Operation The present invention uses the leakage flux generated in the space where the Moore core and the stator core face each other and its surroundings by the magnet as the bias magnetic flux of the magnetic sensor, thereby eliminating the need for a bias magnet and achieving a compact shape. It can be done. Furthermore, the effective stroke of the Movacore can also be made longer.

EXAMPLE Hereinafter, a linear motor according to an example of the present invention will be described with reference to the drawings.

FIG. 1 shows the structure of a linear motor according to a first embodiment of the present invention, and FIG. 2 is a sectional view taken along line AB in FIG. In FIGS. 1 and 2, reference numeral 6 denotes a sensor mounting base, on which a magnetic sensor 8 is fixed, and is fixed to the mover core 2 with screws 7.

The operation of the linear motor configured as described above will be described below with reference to FIGS. 1 and 2.

As shown in FIG. 1, a magnetic flux F1 is formed between the left and right mover cores 2 and the stator by the magnets 3. As shown in Figure 2 (most of the magnetic flux passes through the magnetic pole teeth 1 and 2-1 as the main magnetic flux F, a weak leakage magnetic flux F
2 exists. By applying this deflection magnetic flux as the bias magnetic flux F1 of the magnetic sensor 8, a sensor signal can be extracted without using a bias magnet.

Furthermore, since the shape is compact, the effective stroke of the Movacore can also be long.

Furthermore, if the sensor mounting base is made of a magnetic material, the leakage magnetic flux can be concentrated on the magnetic sensor 8, so that the sensor signal can also be thick (and can be stably extracted).

FIG. 3 is a structural diagram of a linear motor showing a second embodiment of the present invention.

The difference from the structure shown in FIG. 1 is that a convex portion 2a is provided on a part of the mover core 2, and a magnetic sensor 8 is directly fixed thereto. With this configuration, it is possible to concentrate the leakage magnetic flux on the magnetic sensor and generate a large sensor signal of 1q, and also eliminates the need for parts such as the screw 7 and the sensor mounting base 6, making it possible to have a more compact shape. Furthermore, since the magnetic sensor 8 is directly attached to the mover core 2, pitch deviations and gap deviations caused by attachment can be made extremely small, and the quality of the sensor signal is further improved.

Effects of the Invention As described above, the present invention provides a stator having a magnetic pole tooth row formed at a constant pitch in the longitudinal direction, and a group of magnetic pole teeth facing the stator magnetic pole tooth row with the same pitch and a constant gap. A mover core having a plurality of magnetic pole tooth groups whose mutual phases are shifted at a constant rate, a magnet provided between the magnetic pole tooth groups of the mover core, and a space formed by the stator and the mover core facing each other. To provide an inexpensive linear motor that can reduce and simplify the number of mounting parts for a magnetic sensor, lengthen the effective stroke of a mover core, and improve mounting pitch accuracy and reliability by providing a magnetic sensor on which the magnetic sensor is attached. be able to.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the structure of a linear motor in an embodiment of the cylinder 1 of the present invention, FIG. 2 is a sectional view taken along line A-B in FIG. 1, and FIG. 4 and 5 are diagrams showing the structure of a conventional linear motor, and FIG. 6 is a diagram showing the characteristics of a magnetic sensor. 1... Stator, 1-1... Magnetic pole tooth row, 2... Mover core, 2-1... Magnetic pole tooth group, 3...・Magnet, 8...Magnetic sensor.

Claims (3)

[Claims] (1) The mutual phase of a stator having a magnetic pole tooth row formed at a constant pitch in the longitudinal direction and a group of magnetic pole teeth facing the stator magnetic pole tooth row at the same pitch and with a constant gap between them is constant. a mover core having a plurality of magnetic pole teeth groups displaced at a rate of Equipped with a linear motor. (2) The linear motor according to claim 1, wherein the magnetic sensor is disposed in a part of the mover core via a magnetic material. (3) The linear motor according to claim 1, wherein the magnetic sensor is provided in a part of the mover core and fixed to a convex portion of the mover core.