JPH03145960A - Pole tooth profile of stepping motor - Google Patents

Abstract

PURPOSE:To obtain a high torque over a broad range of speed by setting the width of a pole tooth to a specific rate of the magnetized pitch of a rotor magnet in a PM type stepping motor consisting of a stator yoke and the multipolar magnetized rotor magnet. CONSTITUTION:To make small (thin) of the width (tp) of a pole tooth 6 causes that torque in a low speed area becomes smaller and unpractical. The width (tp) of the pole tooth 6 is set wider than 40% of a magnetizing pitch (mp), because there are problems in the workability and economic efficiency when the strength decreases to cause easy bending due to thinning of the pole tooth 6. When the width (tp) of the pole tooth 6 is larger, the maximum width of the pole tooth 6 is less than 70% of the magnetized pitch (mp) because an available speed area is narrow and unpractical.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to the shape of pole teeth of a PM stepping motor.

[Prior art] PM type stepping motor is an inexpensive motor, and FD
It is widely used in information devices such as digital cameras and printers. P
An M-type stepping motor has a stator having a plurality of pole teeth arranged in the circumferential direction, a coil wound around each pole tooth to generate magnetic flux, and a plurality of attachments on the outer peripheral surface facing the stator pole teeth. It consists of a rotor with magnetized permanent magnets. FIG. 3 is a perspective view of the stepping motor, in which numeral 1 denotes a stator and is composed of two stators. 2 is a multipolar magnetized rotor permanent magnet, 3 is a motor shaft, 4 is a coil that excites the yoke, 5 is a flange, and 6 is a plurality of pole teeth provided in the circumferential direction facing the rotor permanent magnet. be.

[Problems to be Solved by the Invention] However, with the conventional technology described above, motor performance cannot be achieved with high torque over a wide speed range (frequency). The shape of the motor's pole teeth and coils were changed to meet the required performance of the equipment used, such as high torque in the high-speed range. Therefore, there have been problems such as the use area of the motor is narrow and it is difficult to use the motor, and the management of the motor is complicated, requiring a lot of management man-hours and causing an increase in costs.

SUMMARY OF THE INVENTION The present invention is intended to solve these problems, and its purpose is to provide a pole tooth shape for a motor that is easy to use and inexpensive, which can provide high torque over a wide range of speeds.

[Means for solving the problem] An outer yoke having a plurality of pole teeth arranged in the circumferential direction;
In PM type stepping motors, which are composed of a stator yoke made up of a combination of inner yokes with a plurality of pole teeth arranged in the circumferential direction, and a multi-pole magnetized rotor magnet, the pole tooth width is determined by the magnetization of the rotor magnet. 40 magnetic pitch
% or more and 70% or less.

[Example] A motor with 200 steps per revolution was manufactured by magnetizing the outer yoke with 50 pole teeth, the inner yoke with 50 pole teeth, and the rotor magnet with 100 poles. Figure 1 is a developed view of the rotor permanent magnets and pole teeth, showing the relationship between the rotor magnets and the pole teeth. 2 is a rotor permanent magnet magnetized with multiple poles, and 6 is a rotor permanent magnet provided opposite to the rotor permanent magnet. It is a polar tooth. The rotor permanent magnet 2 is m
It is multi-pole magnetized with a pitch of p. The width of the pole tooth 6 is t
When p is the ratio of the magnetization pitch mp to the pole tooth width tp and expressed in km (km = t pi m p), there is a deep relationship between the ratio km of the magnetization pitch and the pole tooth width and the motor torque characteristics. Found.

Figure 2 shows the motor torque characteristics, magnetization pitch, and pole tooth width ratio k.
It is a figure showing the relationship with m. In addition, km represents the pole tooth width with respect to the magnetization pitch of the rotor magnet, and when the value of km is small, the pole tooth width tp is narrow, and conversely, as the value of km is large, the pole tooth width tp is wide. .

km where the value of km is small and the pole tooth width is narrow = 0. For 4, the torque decreases in the low speed range, but the decrease in torque is small even in the higher speed range, whereas the km value is large and the pole tooth width is wide = km =
0. 7 can obtain larger torque than km=0.4 in the low speed range. However, in the high speed range, the degree of torque decrease becomes large. The most desirable km value is 0.0, which can be used in a wide range from low speeds to high speeds and can provide high torque. 5~
0. It is 6. If the pole tooth width is set within a range of 50 to 60% of the magnetization pitch, it is possible to meet the demands of most users.

The pole tooth width is km=0. If it is made smaller (thinner) than 4, the torque in the low speed range will become smaller, making it impractical, and the thinner pole teeth will cause problems in workability and economy, such as lowering the strength and making it easier to bend. To avoid this, the pole tooth width was set to 40% or more of the magnetized pitch. Also, km=0.
If it is 7 or more, the usable speed range is narrow and it is not practical, so the maximum width of the pole teeth is set to 70% or less of the magnetized pitch.

[Effects of the Invention] As described above, according to the present invention, high torque can be achieved over a wide range from low speed range to high speed range by setting the pole tooth width to 40% or more and 70% or less of the magnetization pitch of the rotor magnet. Therefore, there is no need to prepare several dedicated motors in response to the user's requests, and it is possible to respond with one motor. This has the effect of reducing management man-hours and reducing costs.

[Brief explanation of the drawing]

Figure 1 is a developed view of the rotor magnet and pole teeth, Figure 2 is a diagram showing the relationship between motor torque characteristics and the ratio of magnetization pitch to pole tooth width, and Figure 3 is a perspective view of a conventional stepping motor. It is.・Stator・Permanent magnet・Motor shaft・Coil・Flange・Pole tooth 2 yIP White 4 Koi Ishi S, V Lance also, Mr. Konegawara

Claims (1)

[Claims] an outer yoke having a plurality of circumferentially arranged pole teeth;
In PM type stepping motors, which are composed of a stator yoke made up of a combination of inner yokes with a plurality of pole teeth arranged in the circumferential direction, and a multi-pole magnetized rotor magnet, the pole tooth width is determined by the polarization of the rotor magnet. 40 magnetic pitch
% or more and 70% or less.