JPS6223353A - Brushless motor - Google Patents

Abstract

PURPOSE:To enable the position of a rotor to be directly detected and facilitate adjustment and enable component parts to be miniaturized, by fixing a non- contact position sensor composed of a substrate with a vaporized thin film magnetic reluctance element, on the inner periphery of a stator core. CONSTITUTION:On the inner periphery of a stator core 4, a non-contact position sensor 7 composed of a substrate with a vaporized thin film magnetic reluctance element is set. The non-contact position sensor 7 is set in close contact with the outer periphery of at least one core 1 of rotor cores 1, 2, and the output of a plurality of electrical signals with the variation in a rough sine wave shape according to the rugged pole teeth of the core 1 and with mutually different phases is generated.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application λ The present invention relates to a brushless motor used in reluctance 1 torque type servo motors used in office automation equipment.

Conventional technology In recent years, Stella I, a reluctance torque motor, has been developed.
Ping motors are used in many office automation equipment because of their good positioning, controllability, and low cost.

Hereinafter, an example of the above-mentioned conventional stepping motor will be described with reference to the drawings.

FIG. 6 shows a structural diagram of a conventional stepping motor. 19 is rotor core 1.20 is rotor core 2.
21 is a permanent magnet, 22 is a stator core, and 23 is a coil. Although the magnetic pole teeth are not shown in the figure, the rotor core 1
．． It is formed on the outer periphery of the magnetic pole tooth groups A, B, C, and D as well as on the inner periphery of the magnetic pole tooth groups A, B, C, and D.

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

The rotor core 1 and the rotor core 2 are arranged with a permanent magnet in between, and are shifted from each other by 1/2 pitch of the magnetic pole tooth pitch. The flow of the magnetic flux is as shown by the solid arrow. Next, the magnetic pole tooth groups A and B of the stator core are arranged to be shifted from each other by 1/4 pitch of the magnetic pole tooth pitch with respect to the rotor magnetic pole teeth. Furthermore, a coil is wound around these magnetic pole tooth groups. The coil magnetic flux is, for example, as indicated by the dotted arrow in the figure. The coil magnetic flux cancels out or strengthens the magnet magnetic flux, causing the rotor to rotate and maintain a magnetically stable state. By changing the energization mode of the coils, the rotor is maintained in its respective magnetically stable state, and by continuously changing the energization mode, rotational motion is obtained. However, stepping motors have a fatal drawback. This means that a tax adjustment phenomenon will occur. If you speed up the switching of the coil's energization mode, the rotor will switch to the next energization mode when it has not reached the magnetic stability point or is in a transient state to an oscillatory stable state. , the rotor becomes unable to follow the input signal. At that time, torque can no longer be extracted. Therefore, it is difficult to extract torque during high-speed rotation, resulting in low power.

To solve this problem, closed-loop driving of stepping motors has been used. This prevents step-out (and allows torque to be extracted during high-speed rotation. In order to perform this closed-loop operation, a position sensor is required to detect the rotor position. This position sensor can also be of magnetic type. There is also an optical type.

FIG. 7 shows the structure of a conventional position sensor and its attachment to a stepping motor.

26 is a stepping motor, 27 is a shaft, 28 is N
S alternately magnetized magnetic drums, 29 magnetic sensors, 3
0 is the sensor mounting base.

The operation of the stepping motor with a position sensor configured as above will be explained below. A magnetic material is coated on the outer periphery of the magnetic drum 28, and is magnetized alternately in NS as shown in the figure. The drum is directly connected to the shaft 27 of the stepping motor 26, and the magnetic sensor 29
By attaching the stepper motor to the frame of the stepping motor, the position of the motor can be detected. The magnetic sensor 29 is made as shown in FIG. The figure shows magnetic sensor 2
9 represents only one phase. (a) shows a state in which one phase of magnetoresistive elements 31 is deposited on a glass substrate 32. (b) shows its equivalent circuit. (c) shows the arrangement of the magnetoresistive elements with respect to the drum and the output state according to their mutual positional relationship.

In reality, two-phase or three-phase multiphase output is often used.

Problems to be Solved by the Invention However, with the above configuration, care must be taken regarding the magnetization state of the magnetic drum, the eccentricity of the magnetic drum, etc. It is also necessary to match the position of the rotor with the position of magnetization of the NS on the drum. Furthermore, since it is attached externally to the stepping motor, there is a problem in that it is not suitable for miniaturization.

In view of the above-mentioned problems, the present invention provides a brushless motor that is suitable for miniaturization, is easy to adjust, and constitutes a rough tangent torque type servo motor.

Means for Solving the Problems In order to solve the above problems, the brushless motor of the present invention is arranged on the inner periphery of the stator core, and at least one of the first core and the second core of the rotor core. A thin film magnetoresistive element is disposed close to the outer periphery of one of the cores, and is made of a substrate on which a thin film magnetoresistive element is deposited, so that it changes in a substantially sinusoidal manner according to the unevenness of the magnetic pole teeth of the core, and is capable of extracting a plurality of electrical signals having mutually different phases. It is equipped with a contact position sensor.

Function: With the above-described configuration, the present invention directly detects the rotating core, so there is no need to consider eccentricity or magnetization. Furthermore, since the motor has a built-in position sensor, it is suitable for miniaturization. Furthermore, since the sensor can be positioned by the stator core, no adjustment is required.

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

FIG. 1 shows a configuration diagram of a reluctance torque type servo motor in one embodiment of the present invention.

In FIG. 1, 1 is a first rotor core, 2 is a second rotor core, 3 is a permanent magnet, 4 is a stator core, 5 is a coil, 6 is a shaft, 7 is a magnetic position sensor, 8 is a sensor holding base, 9 is a stator protrusion provided on the stator core 4,
The sensor holding stand 8 is positioned and supported.

The operation of the reluctance torque type servo motor configured as above will be explained. Although magnetic pole teeth are not shown in the figure, they are formed on the outer periphery of the rotor core 1.2 and further on the inner periphery of the magnetic pole tooth groups A, B, , C, , 'X, U. Rotor core 1 and rotor core 2 sandwich a permanent magnet,
They are arranged to be shifted from each other by 1/2 pitch of the magnetic pole tooth pitch. The flow of the magnetic flux is as shown by the solid arrow.

Next, the magnetic pole tooth groups A, B, and C of the stator core 4 are shifted from each other by 1/3 of the magnetic pole tooth pitch with respect to the rotor magnetic pole teeth. That is, B is shifted by 1/3 pitch with respect to A, and C is shifted by 1/3 pitch with respect to B.

Furthermore, a coil 5 is wound around these magnetic pole tooth groups. The coil magnetic flux cancels out or strengthens the magnet magnetic flux to rotate the rotor and maintain it in a magnetically stable state. By appropriately selecting the energized phase of the motor coil, the motor can continue to rotate.

Next, regarding the sensor, since the motor of this embodiment has three phases, the sensor output also has three phases. FIG. 2 shows the structure of the sensor. The magnetoresistive element 11 deposited on the glass substrate 12 is
Its resistance value changes depending on the strength of the magnetic field applied to it. Regarding only the l-phase, two magnetoresistive elements are arranged with a distance of 1/2 pitch of the magnetic pole tooth pitch. If you wire it as shown in Figure 2 (a), (b
), and the resulting waveform is as shown in Figure 3. Since the rotor core sandwiches a permanent magnet, this becomes a bias magnet, and a magnetic field whose intensity is adjusted by the magnetic pole teeth of the rotor core exists around the outer periphery of the rotor core. By bringing the above-mentioned sensor close to it, a substantially sinusoidal waveform can be obtained as an electrical signal.

Note that the mounting position of the sensor is not unrelated to the stator magnetic pole teeth. Therefore, the sensor 14 or the sensor holding stand 15
To position the stator core 13, as shown in FIG.
It is necessary to establish a

In the above-mentioned embodiment, a three-phase motor was described, but the same can be said of the two-phase motor shown in FIG. In this case, the sensor output will be in two phases.

Effects of the Invention As described above, the present invention provides a non-contact substrate made of a substrate on which thin-film magnetoresistive elements are deposited so that a plurality of electrical signals having mutually different phases can be extracted, changing in a substantially sinusoidal manner according to the irregularities of the magnetic pole teeth of the rotor core. Since the contact position sensor is arranged on the inner periphery of the stator core and is further arranged close to the outer periphery of at least one of the first core and second core of the rotor core, the position of the rotor can be directly detected. This makes adjustment easy, and since the sensor is built into the motor, it is suitable for miniaturization. Furthermore, since the sensor is positioned using at least one protrusion or notch provided on the inner circumference of the stator, there is no need to adjust the mutual positional relationship between the sensor and the stator.
It is possible to place

[Brief explanation of drawings]

FIGS. 1(a) and (b) are a sectional view and a plan view of a motor showing an embodiment of the present invention, FIGS. 2(a) and (b) are a configuration diagram and an equivalent circuit diagram of a position sensor, and FIG. 4 and 5 are sectional views showing the positioning structure of the sensor. FIGS. 6(a) and 6(b) are sectional views and plan views of a conventional stepping motor. Figure 7 a), (
FIG. 8(a), (b), and (C) are a configuration diagram, an equivalent circuit diagram, and an output waveform diagram showing the principle of the conventional position sensor. 1...First rotor core, 2...Second rotor core, 3...Hoss magnet, 4.13...
... Stator core, 5 ... Coil, 7.14
...Position sensor, 8.15...Sensor holding stand, 9.16...Protrusion, 17...
・Notch part. Name of agent: Patent attorney Toshio Nakao (1 person) Figure 1 (b) 1! 2 Figure +■-◎■ (a) (b) Figure 3 oo oo o. Aλ Aλ AA 00 02 op B 100 88 BB No. 4 Figure 13 - Fixed 5 cores (a) (b) (c) (d) Figure 5 b) Figure 7 (a) Figure 8 oo oo o. Aλ Aλ AX

Claims (3)

[Claims] (1) A first core made of a magnetic material having uneven magnetic pole teeth formed at a constant angular pitch on the outer periphery, and a magnetic pole having the same magnetic pole teeth as the first core, A rotating device consisting of a second core made of a magnetic material whose teeth are shifted by 1/2 pitch of the magnetic pole tooth pitch, and a permanent magnet sandwiched between the two cores and magnetized in the thickness direction. A child core faces the rotor core while maintaining a slight gap,
a stator core made of a magnetic material having a plurality of magnetic pole tooth groups having a plurality of magnetic pole teeth having the same angular pitch as the magnetic pole teeth of the rotor core; a coil wound around the magnetic tooth group; and the stator. is arranged on the inner periphery of the rotor core, is arranged close to the outer periphery of at least one of the first core and the second core of the rotor core, and is arranged in a substantially sinusoidal shape according to the unevenness of the magnetic pole teeth of the rotor core. A brushless motor equipped with a non-contact position sensor consisting of a substrate on which a thin film magnetoresistive element is deposited so that multiple electrical signals that change and have different phases can be extracted. (2) The brushless motor according to claim 1, wherein at least one protrusion is provided on the inner circumference of the stator core to position the sensor or the sensor holding stand. (3) The brushless motor according to claim 1, wherein at least one notch is provided in the inner circumference of the stator core to position the sensor or the sensor holding stand.