JPS631020B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a brushless electric motor, and more particularly to a mounting structure for a Hall element that detects the position of a rotor.

Hall elements are widely used as magnetically sensitive elements in brushless motors in which the rotor position is detected by a magnetically sensitive element, and the detected output drives and controls a power transistor to sequentially energize each armature winding. It is being

This Hall element, as shown in FIG.
If the arrangement is not made so that the magnetic flux crosses perpendicularly to the sensing surface Z, the Hall voltage that is the output signal will be small and the variation will be large, making it impossible to perform sufficient control. Various efforts have been made to date.

For example, as shown in FIG. 7, a position detection magnet 23 having the same number of magnetic poles as the rotor 22 is provided on the rotating shaft 21 of the electric motor, and the position detection magnets 23 are arranged around the position detection magnet 23 at equal angles to each other. At the interval,
A mounting plate 24 for mounting the Hall element having a facing surface horizontally facing the magnet 23 is formed, and the Hall element 12 is mounted on the inner diameter side of this mounting plate.

Although not shown, a mounting plate for the Hall element is provided extending axially from the inner surface of the end bracket of the motor for a position detection magnet having the same number of magnetic poles as the rotor. It is also possible to attach the Hall element on the inner diameter side so that the detection surface of the Hall element is close to and faces the position detection magnet.

However, in these conventional methods, (1)
The Hall element is small, for example, 3 mm x 3 mm x 1.6 mm, so it is difficult to install. (2) Accurate positioning,
It has various problems, such as being difficult to fix and easily causing variations in Hall voltage, conduction line width, etc., and (3) making the Hall element mounting plate and its mounting structure complicated.

The present invention has been made in view of the above circumstances, and it is possible to easily install the Hall element so that the detection surface faces the magnet rotor or the detection magnet, and to prevent variations in the mounting position of the Hall element. The purpose of the present invention is to provide a brushless electric motor that can be driven and controlled stably without causing problems.

The present invention will be explained below based on embodiments shown in the drawings.

FIG. 1 is a longitudinal cross-sectional view of a brushless motor according to the present invention, FIG. 2 is a view showing a board for mounting a Hall element, and FIG. 3 is a cross-sectional view taken along line A-A. Further, FIGS. 4 and 5 are enlarged views of essential parts for explaining the mounting state of the Hall element, and FIG. 6 is a diagram showing another embodiment of the present invention.

In FIG. 1, 1 is the stator of the electric motor,
The winding 3 is formed by winding a coil annularly in each slot of the iron core 2, and the FRP is applied from the outer periphery.
The frame 4 is formed by integrally molding a resin material such as (Fibered Resin Plastic).

Reference numeral 5 denotes a rotor of an electric motor, and a magnet 6 is attached to the outer periphery of the rotor to constitute a magnet rotor.

7 is a rotating shaft of the rotor 5, and end brackets 10, 1 are fitted and attached to the frame 4.
1 via shaft supports 8 and 9.

On the inside of the motor of the frame 4, a rotor 5 is located slightly axially inward from the end of the magnet 6 of the rotor 5.
a stepped portion 4a formed in a concentric disc-shaped groove;
The side wall of this step 4a is cut out to form the step 4a.
A step portion 4b of a horizontal groove communicating with the outside of the electric motor on the same surface as the groove is integrally provided with resin at the time of frame formation.

The Hall element 12 is a board 13 for mounting the Hall element.
This board 13 is formed of a flat double-sided wiring board such as a PC board, and includes a disk portion 13a having a hole 14 larger in diameter than the magnet 6 of the rotor 5, and a hole 14 from this disk portion 13a. Drawer part 13 extending in one direction
It is composed of b.

A notch 15 for attaching a Hall element is formed in the inner circumference of the hole 14 of the substrate 13 in a radial direction from the inner circumferential surface.

As shown in FIGS. 4 and 5, the Hall element 12 has a sensing surface Z with respect to the inner peripheral surface of the substrate 13.
are arranged at almost right angles, and each output terminal is attached to each notch 15 so as to straddle the inner peripheral surface of the board 13, and the output terminal is soldered to the wiring pattern on both sides to connect the electrical A physical connection is made.

The board thickness of the board 13 and the size of the notch 15 are determined according to the dimensions and shape of the Hall element 12. For example, it is preferable that the board thickness of the board 13 be set to the distance t between the output terminals of the Hall element 12, and the distance between the output terminals By making the distance t and the thickness of the substrate 13 substantially equal, the terminal wire can be connected to the wiring pattern without bending, so that no mechanical strain is applied to the terminal portion of the Hall element 12 due to bending. Damage to parts can be prevented and reliability can be improved. Furthermore, installation becomes easier.

The dimensions of the notch 15 are also determined by the width of the Hall element being b,
Assuming that the thickness is d, if the width in the circumferential direction is approximately b and the depth in the radial direction is approximately d, positioning and mounting of the Hall element 12 will be easy, and the small Hall element 12 will be It can be installed accurately in a predetermined position and can be securely fixed.

Since the Hall elements 12 do not protrude from the inner circumferential surface of the substrate 13 and have substantially the same height, they do not come into contact with each other due to eccentricity of the rotor during assembly.

Actually, the dimensions of the Hall element 12 are 3 mm x 3 mm x
1.6 mm (a x b x d), distance between terminals 1.6 mm (t), board 13 thickness 1.6 mm, notch width and depth dimensions of 3 mm and 1.6 mm, respectively, is an extremely excellent detection device. is obtained.

The substrate 13 is attached with its disc portion 13a in close contact with the stepped portion 4a of the frame 4, and its pull-out portion 13b in close contact with the stepped portion 4b, respectively, and the stepped portions 4a and 4b are used for axial and radial positioning.

Therefore, the detection surface Z of the Hall element 12 to which the substrate 13 is attached faces the outer peripheral surface of the magnet,
And they are arranged close to each other on concentric circles.

Although it is sufficient to fix the substrate 13 by adhesive means such as adhesion, it is preferable to bring the substrate 13 into close contact with the step portions 4a and 4b and then sandwich it between the end brackets 11 with an insulating plate (not shown) interposed therebetween. You can also do it.

The drawn-out portion 13b of the board 13 is exposed to the outside of the motor, and a brushless motor is constructed by connecting a power source and a control mechanism to the wiring pattern of this exposed portion.

According to the above configuration, since the detection surface Z of the Hall element 12 is arranged facing the magnet 6 of the rotor 5, which is the object to be detected, the Hall element 12 operates efficiently and provides a stable output with little variation in Hall voltage. Obtainable.

Furthermore, since a flat wiring board can be used as the substrate 13 for mounting the Hall element, the structure can be extremely simplified, and the mounting space can be reduced to improve the mounting density inside the motor.

Further, since a notch 15 for attaching the Hall element is formed in the inner peripheral surface of the substrate 13 and the Hall element 12 is attached within this notch 15, accurate positioning and fixing can be easily performed.

This notch 15 can be integrally formed by press working when creating the substrate 13, and has a simple structure and is extremely easy to manufacture.

By bringing this board 13 into close contact with the stepped portions 4a and 4b formed inside the motor, the board 13
3 can be accurately positioned and easily fixed by gluing or the like, so the mounting structure of the board 13 is also simplified.

On the other hand, as for the mounting structure of the board 13, as shown in FIG.
The stepped portion 3 is formed inside the steel plate bracket 31 by press drawing or by welding parts.
The same effect can be obtained by forming a substrate 13 on which the Hall element 12 is fixed.

Moreover, instead of detecting the leakage magnetic flux of the magnet 6 of the rotor 5, a detection body having the same number of magnetic poles as the rotor 5 is provided on the rotating shaft 7, and a Hall element 1 is attached to this detection body.
Similar effects can be obtained even when the substrates 13 are attached so that the substrates 2 face each other.

Further, by making the substrate 13 a double-sided wiring board, the output terminals of the Hall element 12 can be wired on each side, which makes the work easier and the wiring pattern itself can be simplified.

As explained above, according to the present invention, it is possible to efficiently operate the Hall element to obtain a stable output with little variation, and it is also possible to easily install the Hall element without causing variation in the mounting position. A brushless electric motor can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a vertical sectional view of a brushless motor according to the present invention, FIG. 2 is a diagram showing a board for mounting a Hall element, FIG.
FIG. 5 is an enlarged view showing how the Hall element is mounted, FIG. 6 is a diagram showing another embodiment of the present invention, and FIG. 7 is a diagram showing an example of the conventional Hall element mounting state. FIG. 8 is a diagram showing the general shape of a Hall element. 12... Hall element, 13... Substrate, 15...
Notch, 4a, 4b, 32...Stepped portion, Z...Detection surface.

Claims (1)

[Claims] 1. In a brushless motor that detects a magnetic signal output from a detected object in response to the rotational position of the rotor using a Hall element, and energizes the armature winding in response to this detection signal, a brushless motor consists of a cylindrical magnet. A double-sided wiring board for mounting a Hall element is provided, which forms a rotor and has a large diameter hole that passes through the rotor. 1. A brushless motor, characterized in that the brushless motor is mounted so as to straddle double-sided wiring, and has a stepped portion for mounting a board inside the motor so that the board faces the rotor.