JPH0426348A - synchronous motor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] 3. Detailed description of the invention [Industrial application field] The present invention relates to the structure of a synchronous motor.

[Prior Art] For example, there is a single-phase step motor in which the shape of the pole teeth is asymmetric, as in the Japanese Patent Publication No. 50-83.

[Problems to be Solved by the Invention] However, in the conventional technology described above, since the stepping motor is used, a pulse signal must be applied to drive it. For example, in a computer with a built-in microprocessor and a control system, It is possible to use a signal from a losser, but if the device does not have such a signal generating device, a new means for generating a drive signal is required, which is expensive. Furthermore, when stepping motors are rotated at high speeds or subjected to high loads, there is a so-called step-out phenomenon in which they become unable to synchronize with the input signal, and sometimes the direction of rotation is not determined and the motor may reverse. Ta.

Therefore, the present invention aims to solve such problems.The purpose of the present invention is to provide a low-cost drive circuit that does not require pulse signals, and which is capable of preventing step-out or reversal even under high-speed rotation and high load. To provide a synchronous motor that can always rotate in one direction without any problems.

[! ! [Means for solving the problem] A rotor that is a cylindrical permanent magnet magnetized with multiple poles, and a circular asymmetric shape that exerts a force that rotates the rotor in a certain direction when it changes from a non-excited state to an energized state. The same number of pole teeth are arranged facing the rotor magnet in the circumferential direction, and it is equipped with a sensor that detects the rotation angle of the rotor magnet and switches the direction of the current flowing through the excitation coil, and rotates in one direction. Features.

[Example] Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a sectional view of the synchronous motor of the present invention, and the rotor is composed of a rotor magnet 1 which is a cylindrical permanent magnet magnetized with multiple poles, a yoke 2, and a shaft 3. On the outer periphery of the rotor magnet 1, a plurality of pole teeth 5 of the stator 4 and a plurality of pole teeth 6 of the stator 4' are arranged alternately in the circumferential direction, facing the poles of the rotor magnet. A sensor 7 for detecting the rotation angle of the rotor magnet l is disposed at one location between the rotor magnet l and the pole tooth 6. The pole teeth 5 and 6 are formed by bending stators 4 and 4' made of high magnetic permeability thin plates inward in the circumferential direction. An annular excitation coil 8 is housed in the stator. The stators 4 and 41 are fixed to the flanges 10 and 10', and the rotors are built into bearings 9 which are also fixed to the flanges 10 and 10'.

FIG. 2 is a developed view of the pole teeth and the sensor rotor magnet for explaining the relationship between the pole teeth, the sensor, and the poles of the rotor magnet and their operation according to the present invention. FIG. 2(a) is a developed view in a non-excited state, in which a large number of pole teeth 5 of the stator 4 and a large number of pole teeth 6 of the stator 4° are alternately arranged facing the multi-poles of the rotor magnet 1. ing. A sensor 7 for detecting the rotation angle of the rotor magnet is installed in a part between the pole teeth 5 and 6.

In this embodiment, a Hall sensor was used to detect the rotation angle of the rotor from changes in the magnetic flux of the rotor magnet. The sensor 7 is placed offset from the center of the rotor magnet 1 and the pole tooth 5. This is because the shapes of the pole teeth 5 and 6 are asymmetrical, and the position where the magnetic resistance is minimum is a position slightly shifted from the center of the pole of the pole teeth 5 and 6 and the rotor magnet 1.

Further, in the excitation state, since the pole teeth 5 and 6 are similarly asymmetrical, the timing at which the excitation current is switched changes. FIG. 5 is a drive circuit diagram of the motor of the present invention,
12 is a DC power supply; 11 is a unipolar drive circuit of transistors for switching the current flowing through the coil 8; The sensor 7 turns the transistor 11 ON and OFF alternately by sensing the N pole and S pole of the rotor magnet.
F to excite the right A phase of the coil 8 and the left one to drive the motor.

Next, an excitation state in which a current is passed through the excitation coil 8 will be explained. Figure 2 (a) shows a state in which the sensor 7 detects the NWA of the rotor magnet l from a stationary state, and the stator 4 and pole teeth 5 are excited to the S pole, and one stator 4° and 6 are excited to the N pole. (the excitation coil is not shown), the pole teeth 5 attract the S pole of the rotor rotor magnet 1, and the pole teeth 6 attract the N pole of the rotor rotor magnet 1, and the rotor magnet moves to the right as shown by the arrow in the figure ( At this time, the shape of the pole teeth is asymmetrical, so when the rotor magnet 1 rotates and the maximum torque is obtained, it should not be located near the center of the pole tooth shape and the center of the pole of the rotor magnet 1, but as shown in the figure. In the case of shape, it shifts to the right.

If the pole tooth shape is made asymmetrical so that it protrudes to the right, the stable point of the rotor magnet in the non-excited state will be at the position where the magnetic resistance is minimized near the center of gravity of the pole tooth shape.

In the excitation state, the protrusion on the right side has a stronger force acting on the rotor magnet, so the rotor moves to the right.

Next, a case where the rotor magnet 1 advances (rotates) and the boundary line between the S pole and the N pole of the rotor magnet 1 reaches the position of the sensor 7 will be described. FIG. 2(b) is a developed view explaining when the boundary line between the poles of the rotor magnet 1 comes to the position of the sensor 7. At this time, the sensor 7 cannot receive magnetic flux from the rotor magnet l. No signal is output to the transistor, so no current flows through the excitation coil either, resulting in a non-excitation state.

The rotor magnet 1 cannot remain stationary at this position, so it moves to the right until it reaches the stable point of minimum magnetic resistance, as shown in Figure 2 (
c) is a developed diagram illustrating the state when the next stable point has been reached; the sensor 7 detects the S pole of the rotor magnet, the stator 4 and the pole teeth 5 are set to the N pole, and one stator 4 is set to the N pole. ' and pole tooth 6
is excited to the S pole. Similarly to (a), a force acts on the rotor and the rotor magnet 1 moves in the direction of the arrow on the right.
) By repeating step (C), continuous rotation in one direction becomes possible.

FIG. 4 is a developed view when the shape of the pole teeth is changed, and the same effect as described above was obtained even with such a shape.

As mentioned above, not only is it possible to always start in one predetermined direction from a stationary state, but the excitation of the pole teeth is switched by determining the polarity of the rotor magnet, so even if a large load is applied, it will not rotate. There is no possibility of reverse direction or loss of synchronization.

In this embodiment, a Hall element is used as the sensor for detecting the rotation angle of the rotor magnet, but it is also possible to use an encoder, magnetostrictive cable, etc. to detect the rotor angle and switch the excitation. It is possible to obtain the following effects.

[Effects of the Invention] As described above, according to the present invention, a plurality of asymmetrical pole teeth facing each other alternately in the circumferential direction are arranged,
By switching the direction of the current flowing through the excitation coil according to the rotation angle of the rotor, it is possible to always self-start in one direction, and even when a load is applied to the motor, it is always possible to rotate in one direction. This structure has a small number of parts and a simple shape, so it is inexpensive and has excellent productivity.

[Brief explanation of drawings]

FIG. 1 is a sectional view of the synchronous motor of the present invention, and FIG. 2(a)
(b) and (c) are exploded views of the pole teeth and the rotor magnet for explaining the relationship and operation between the pole teeth and the sensor rotor magnet poles, and FIG. 3 is a drive circuit diagram of the motor of the present invention. FIG. 4 is a developed view when the shape of the pole teeth of the present invention is changed.・Rotor magnet ・Yoke ・Shaft 4゛ ... Stator 6 ... Pole tooth ・Sensor coil ・Bearing 10' ・Flange 1 ・ 2 ・ 3 ・ 4. 5. 7 ・ 8 ・ 9 ・ 10. 1 l ・ 12 ・ ・Transistors, power supplies and above Applicant: Seiko Epson Corporation Representative Patent Attorney Kizobe Suzuki and 1 other person Figure 3

Claims (1)

[Claims] The rotor is a cylindrical permanent magnet magnetized with multiple poles, and the rotor magnets are asymmetric in shape and are opposed to each other in the circumferential direction, where a force is exerted that rotates the rotor in a certain direction when it changes from a non-excited state to an energized state. A synchronous motor is characterized in that it has a configuration in which the same number of pole teeth are arranged, and is equipped with a sensor for detecting the rotation angle of a rotor magnet and switching the direction of current flowing through an excitation coil, and that it rotates in one direction.