JPH04197070A - Brushless servo motor - Google Patents

Abstract

PURPOSE:To reduce manpower in assemblage and to facilitate molding of resin by providing a multipolar magnetic drum mounted coaxially with a rotor magnet for generating torque and a magnet for commutation sensor. CONSTITUTION:A brushless motor comprises a rotor magnet 23 which contributes to generation of motor torque and a magnet for commutation sensor constituted into a single ring magnet. A magnetic short ring 31 is mounted on the end face of a magnetic drum 32 so that the magnetic drum is not subjected to leakage flux from the magnet, and the magnetic drum 32 is mounted through the magnetic short ring 31. In other words, when a multipolar magnetic drum 32 is mounted coaxially with a magnet 23 for generating torque and a magnet for commutation sensor, magnetic interference between the magnetic drum and other magnets can be avoided and resin molding of motor is facilitated resulting in an inexpensive motor excellent in water resistance.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a brushless servo motor incorporating a magnetic encoder.

BACKGROUND OF THE INVENTION In recent years, brushless servo motors have come to be widely used in the mechatronics field due to their high-speed response and maintenance-free nature. Recently, brushless servo motors have also begun to be considered in addition to stepping motors in the field of car electronics. This is because the positioning resolution is much higher than that of the conventional mainstream control using a solenoid, and furthermore, it has characteristics of faster response than a stepping motor and lower noise.

A conventional brushless servo motor will be explained below.

FIG. 6 is a structural sectional view of a brushless servo motor having a magnetic encoder.

1 is a shaft, 2 is a rotor core, 3 is a rotor magnet, 4 is a stator core, 5 is a motor frame, 6 is a bracket,
7 and 8 are bearings, 9 is a commutation sensor magnet,
10 is a Hall element or Hall IC 111 is a printed wiring board, 12 is a magnetic drum, 13 is a magnetoresistive element, 14 is a boss, and 15 is an encoder cover.

The operation of the brushless servo motor configured as above will be explained below.

First, shaft 1 and rotor core 2. The rotor magnet 3 is fixed. This rotor assembly is connected to the motor frame 5 through bearings 7 and 8. Combined with bracket 6. On the other hand, a magnetic drum 12 and a commutation sensor magnet 9 are fixed to the boss 14. The commutation sensor magnet 9 is normally magnetized to have the same number of poles as the rotor magnet 3. Further, the magnetic drum 12 is multi-pole magnetized according to the positioning resolution required of the brushless servo motor. The commutation sensor magnet 9 and the magnetic drum 12 are mounted on the side of the shaft 1 opposite to the output shaft. Further, a Hall element or Hall ICl0 is disposed on the printed wiring board 11 positioned with respect to the motor frame 5 so as to face the commutation sensor magnet 9. Further, a magnetic resistance element 13 is arranged to face the magnetic drum 12 described above.

Problems to be Solved by the Invention However, in the conventional configuration, the sensor magnet was attached from the side opposite to the output shaft after the motor section was assembled. assembly.

An example of difficult adjustment is that the coaxiality between the inner diameter of the boss 14 and the outer diameter of the magnetic drum 12 must be within 5 μm, and a high-precision jig and many man-hours are required when press-fitting the boss 14 onto the shaft 1. was. Furthermore, after the rotor core 2, rotor magnets 3, bearings 8, etc. are attached, it is necessary to inspect the deflection of the opposite output shaft of the shaft 1, which increases the number of assembly and inspection steps. Furthermore, when the motor frame 5 and the bracket 6 are made by resin molding, the encoder part cannot be integrated, so it is difficult to obtain any advantage from resin molding.

In view of the above-mentioned problems, an object of the present invention is to provide a brushless servo motor that is inexpensive and has excellent water resistance, which can reduce the number of assembly steps and can be easily molded with resin.

Means for Solving the Problems To achieve this object, the brushless servo motor of the present invention consists of a rotor magnet part that contributes to motor torque generation and a commutation sensor magnet part, which are composed of one ring-shaped magnet, and the leakage magnetic flux is reduced. A magnetic short section made of a magnetic material is attached to the end face of the magnetic drum so as not to affect the magnetic drum, which will be described later, and the magnetic drum section is attached via the magnetic short section.

Function: This configuration allows the magnetic drum section to be installed later.
, a magnetic encoder can be configured, making it possible to significantly reduce assembly man-hours. Furthermore, since the encoder section is disposed between the input and output bearings, the stator can be configured into a cup shape, which improves the effectiveness of resin molding.

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

FIG. 1 shows a structural sectional view of a brushless servo motor according to an embodiment of the present invention.

In FIG. 1, 21 is a shaft, 22 is a rotor core,
23 is a rotor magnet, 24 is a stator core, 25 is a frame, 26 is a bracket, 27.28 is a bearing, 29 is a Hall element or Hall IC 130 is a printed wiring board, 31 is a magnetic short ring, 32 is a magnetic drum, 33 is a magnetic resistance The element 34 is a magnetic drum boss, and 35 is a C ring.

FIG. 2 shows the motor shown in FIG. 1 in a resin molded state.

The operation of the brushless servo motor of this embodiment configured as described above will be described below.

First, printed wiring board 30 is placed opposite stator core 24 . For this purpose, a part of the insulator inserted into the stator core may be used for positioning and holding. Next, the magnetoresistive element 33 disposed on the printed wiring board 30 and the magnetic drum 32 are fixed using a jig or the like so that the gap between them is appropriate. In this state, the stator core assembly is attached to the frame 25 and bracket 26.
Insert and fix into a frame assembly consisting of.

Next, the already magnetized rotor assembly is inserted into the stator assembly and fixed with the C-ring 35.

As described above, according to this embodiment, the magnetic drum is integrated on the rotor, which greatly simplifies the assembly process, resulting in a significant cost reduction effect.

Further, magnetic interference between the magnetic drum 32 and the rotor magnet 23 is reduced by the magnetic short ring 31.

FIG. 3 is a diagram showing magnetic leakage at the end face of the rotor magnet 23. Leakage magnetic flux is generated at the end face as shown in the figure. This magnetic field is strong enough to interfere with the magnetic field of the magnetic drum 32, and depending on the brushless servo motor, this end face magnetic flux can be used to generate a commutation signal.

The magnetic short ring 31 completely absorbs this end face magnetic flux. However, if the Hall element or Hall IC 29 detects the magnetic field near the end face of the rotor magnet, the operating point of the magnet will drop significantly near the magnetic short ring 31. It is possible to maintain the magnetic field near the end face above a certain level by fixing the end face with a small gap between the ends.

Other embodiments of the present invention will be described below with reference to the drawings.

In FIG. 5, 21 is a shaft, 22 is a rotor core,
23 is a rotor magnet, 36 is a commutation sensor magnet, 37 is a holder for the commutation sensor magnet 36, 32 is a magnetic drum, 38 is a holder for the magnetic drum 32, and 39 is a spacer.

The structure of the encoder section of the brushless servo motor configured as above will be explained below.

The holder 37 is made of a magnetic material such as an iron-based material, and functions as a magnet holder and a magnetic short section at the same time. Commutation sensor magnets do not need to be as strong as rotor magnets;
In order to reduce costs, it may be better to separate them.

Effects of the Invention The present invention can significantly reduce assembly man-hours by providing a multi-pole magnetized magnetic drum coaxially arranged with the torque generating rotor magnet and the commutation sensor magnet. Further, by providing a magnetic short section, magnetic interference between the magnetic drum and other magnets can be avoided. Furthermore, by adopting this structure, the motor can be easily molded with resin, and a brushless servo motor that is inexpensive and has excellent water resistance can be realized.

[Brief explanation of the drawing]

Fig. 1 is a structural cross-sectional view of a brushless servo motor according to an embodiment of the present invention, Fig. 2 is a cross-sectional view of a brushless servo motor having a resin molded structure of the present invention, and Fig. 3 is a magnetic leakage of the rotor magnet end face. FIG. 4 is an explanatory diagram of a magnetic short ring, FIG. 5 is a detailed diagram of a brushless motor according to another embodiment of the present invention, and FIG. 6 is a structural sectional view of a conventional brushless servo motor. 1.21...Shaft, 2,22...
Rotor core, 3, 23... Rotor magnet for torque generation, 4° 24... Stator core, 5, 25...
...Frame, 6,26...Bracket, 7.8.27.28...Bearing, 9,36...
... Commutation sensor magnet, 10.29.
...Hall element or Hall IC111, 30...
...Printed wiring board, 12.32...Magnetic drum, 13.33...Magnetic resistance element, 14゜34...Boss, 15...・Cover, 31
...Magnetic short ring, 35...C
Ring, 37.38...Holder, 39...
··Spacer. Name of agent: Patent attorney Haruaki Ogata and 2 others＼
Cup figure 5

Claims (5)

[Claims] (1) In a permanent magnet rotation type motor, a brushless servo motor has a magnetic drum that is arranged coaxially with a torque-generating rotor magnet and a commutation sensor magnet that contribute to motor torque generation, and has a multi-pole magnetized outer periphery. . (2) The magnetoresistive element for detecting magnetic changes on the outer circumferential surface of the magnetic drum according to claim 1 is fixed on a printed wiring board on which the detected signal processing circuit, the commutation sensor, and the signal processing circuit are mounted, The printed wiring board is
The brushless servo motor according to claim 1, wherein the brushless servo motor is positioned and held by a portion of an insulator inserted into the stator core. (3) The rotor magnet or the commutation sensor magnet according to claim 1 has a magnetic short portion made of a magnetic material on the end face thereof, and a magnetic drum is disposed at a certain gap from the magnetic short portion. brushless servo motor. (4) The brushless servo according to claim 1 or 3, wherein the magnetic short portion according to claim 3 is arranged with a slight gap between the end face of the rotor magnet or the commutation sensor magnet. motor. (5) A brushless servo motor according to claim 1, wherein the main magnet and the commutation sensor magnet are separated, and the holder of the commutation sensor magnet forms a magnetic short section.