JPH0686526A - Brushless dc motor - Google Patents

Abstract

PURPOSE:To provide a brushless DC motor which makes the use of a single- sided circuit board possible, makes magnetic poles for polarity detection of the rotor magnets unnecessary, and improves the arrangement and fitting of the coils of a frequency generator and a hall element to the circuit board. CONSTITUTION:Concerning to brushless DC motor provided with a rotor 3 consisting of rotor magnets 5 and magnets for a frequency generator 4, a stator 6 opposed to this rotor, and a circuit board 1, stepped parts 4c or grooves are provided at the parts of the magnets 4 for a frequency generator. Along with it, a surface-fitting Hall element 16 is arranged on the circuit board 1 as a magnetic pole detecting element for the rotor magnets 5. To this circuit board 1, frequency generator coils 15 are fixed by soldering as individual electronic parts formed into modules. And these frequency generator coils 15 are arranged on a high-permeability material such as an iron board, etc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a DC brushless motor used in office equipment such as LBP and PPC.

[0002]

2. Description of the Related Art The prior art is disclosed in JP-A-58-179.
It was constructed as shown in Japanese Patent Publication No. 150. Next, the essential points of the configuration will be described with reference to FIGS. FIG. 9 is a partially longitudinal front view showing the structure of a conventional DC brushless motor. In the figure, 1 is a circuit board, 2 is a bracket, and 3 is a rotor. The rotor 3 is composed of a frequency generator magnet 4, a rotor magnet 5, a holder-3a for holding them, and a shaft 13 integrally supporting the holder-3a and the bush 3b. The frequency generator magnet 4 is provided at the tip of the rotor magnet 5. Reference numeral 6 is a stator, and 6a is a stator winding. The stator 6 is arranged so as to face the rotor magnet 5 with a small gap, and includes a bearing housing 9 and a ball bearing 1.
It is supported by the rotary shaft 13 via 1a and 11b. In addition,
8 is a nylon clip, 10 is a screw, 12 is a snap ring,
The rotor 3 can freely rotate around the stator 6. On the other hand, the frequency generator coil 7 is arranged on the circuit board 1 so as to face the frequency generator magnet 4 with a slight gap therebetween. FIG. 10 is an enlarged front view of the main part of the frequency generator magnet 4 and the rotor magnet 5 shown in FIG. 9 in an enlarged manner. As shown in the figure, the inner circumference of the rotor magnet 5 is magnetized. In the vicinity of the magnetic pole detecting magnetic pole portion 4b having the same polarity as the polarized magnetic pole portion 5a, a magnetic pole detecting hall element 16a to be described later with reference to FIG.
16c is arranged on the back side of the circuit board 1 by soldering. FIG. 11 shows the arrangement structure of the frequency generator coil 7,
Reference numeral 1 is a circuit board, 7 is a frequency generator coil, and 7a is a coil pattern formed on the circuit board 1. The coil pattern is provided about 360 ° with respect to the center of the frequency generator magnet 4 in the area where the magnetic pole exists. To be In addition, 16a to 16c are hall elements for magnetic pole detection.

As shown in FIG. 10, the magnets 4 and 5 are magnetized in the direction A (radial inner circumference) for motor drive, and are magnetized to have a magnetic pole portion 5a and a collar portion which have the same poles as the magnetic pole portion 5a. The magnetic pole portion 4b for magnetic pole detection and the magnetic pole portion 4a for frequency generator for speed detection are arranged in parallel and magnetized in the B and C directions, respectively. The magnetic pole portion 4b for magnetic pole detection is shown in FIG.
The polarity is detected by the loop elements 16a, 16b, 16c to switch the current to the stator winding 6a to drive the motor, and the frequency generator magnetic pole portion 4a and the frequency generator coil 7 of FIG. The output of the frequency generator is detected by the interaction of the coil pattern 7a, and the control device controls the speed.

[0004]

By the way, in the case of the above-mentioned conventional structure, there are the following problems. The coil pattern of the frequency generator coil is formed directly on the circuit board. Since the rotor and the stator are arranged in the same direction as the coil pattern surface, the space is limited. It was difficult to place all electronic components on the coil pattern side, and therefore it was difficult to make the circuit board on one side. Since the pole element for magnetic pole detection is arranged immediately below the magnetic pole for magnetic pole detection, the position and arrangement with the coil pattern existing over almost the entire circumference is limited, and there is a large design limitation. Since the hall element for magnetic pole detection is to be mounted, the magnetic pole for magnetic pole detection having the same polarity as the rotor magnetic pole must be provided in parallel with the frequency generator magnetic pole separately from the inner circumference of the rotor magnet. was there. SUMMARY OF THE INVENTION It is an object of the present invention to provide a DC brushless motor that solves the above problems (problems) of the conventional one.

[0005]

In order to solve the above problems (problems), the DC brushless motor of the present invention is provided with a step portion or a groove portion in a part of a magnet for a frequency generator, A fan-shaped frequency generator coil part, which is formed by forming a coil pattern on a substrate of high magnetic permeability material such as an iron substrate, is assembled on a circuit board as one electronic component. With a slight gap between them, the magnets for the frequency generator are made to face each other. On the other hand, a square hole for positioning the hall element is provided on the back side of the circuit board, and the hall element is inserted into this square hole from the back side of the board. On the other hand, a pattern for soldering and fixing four hole element lead terminal portions on the back surface of the board.
Land and fix it by imposition. By doing so, the surface of the hall element is arranged on the front side of the circuit board, at a position slightly submerged from the surface of the board, with the magnetically sensitive surface facing the front side, and the magnetic pole magnetized on the inner circumference of the rotor magnet. Is configured to detect. In this case, the fixing of the hole element shall be such that the lead terminal is faced to the pattern land as described above, and the direction of the hole element is aligned with the soldering direction when soldering to the circuit board. Arrange them so that soldering work is easy. The center angle between the center of the frequency generator coil and the center of the hall element is arranged in the region of 90 ° to 270 °.

[0006]

In the above structure, since the frequency generator coil is prepared as one electronic component, it is possible to realize a single-sided board, and a high-permeability material such as an iron board is used as a back yoke. The output of the generator has been increased. In addition, the space which has been conventionally 360 ° is reduced to a range of 1/2 to 1/4. When the fan shape is used, the space of the generator coil on the circuit board is greatly reduced. Conventionally, due to this space saving, there was a design restriction on the placement of the hall elements, but there was a margin for placing at least the remaining space on the circumference. In addition, the axial magnetic flux leaking from the magnetic poles magnetized inside the rotor magnet is faced by providing a step or groove in a part of the magnet for the frequency generator, which is the end face of the flange of the rotor magnet. Even if it is directly detected by the Hall element, it is possible to detect without receiving magnetic interference from the frequency generator magnet and without giving magnetic interference.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the embodiments of FIGS. 1 to 3 shown in the drawings. First Embodiment: FIG. 1 is a vertical sectional front view showing a basic structure of a DC brushless motor to which the present invention is applied. In the figure, the components corresponding to those of the conventional one are denoted by the same reference numerals as those in FIG. For the sake of simplicity, each hole element 1 of the present invention is
6A to 16C may be collectively referred to as the hall element 16 in the following description. That is, in the present invention, the step portion 4c is provided in a part of the frequency generator magnet 4 provided in the flange portion of the rotor magnet 5, and the frequency generator coil portion 15 is provided on the circuit board 1 as one electronic component. As a result, the frequency generator magnet 4 is faced to the generator coil portion 15 with a slight gap. In addition, a plurality of hole elements 1 are provided on the back side of the circuit board 1.
6 is arranged to detect the magnetic pole by receiving the axial flux leaked in the axial direction from the magnetic pole magnetized on the inner circumference of the rotor magnet 5 by the hall element 16.

2 to 5, the frequency generator coil portion 15 and the coil portion 1 of the circuit board 1 of the present invention are mainly used.
An embodiment of a method of fixing the coil element 15 and a method of combining the coil element 15 and the respective hall elements 16 including the arrangement of the hall elements 16 will be described. As shown in FIGS. 2 and 3, in the circuit board 1, a fan-shaped frequency generator coil unit 1 in which a coil pattern 15a is formed on a board 15f made of a material having a high magnetic permeability such as iron.
5 as one electronic component is positioned on the circuit board 1 by the positioning portions 15b and 15c, and the jumper wire 1
It is fixed by soldering with 5d and 15e. In FIG. 3, the positioning portions 15b and 15c for the circuit board 1 and the generator coil portion 15 are formed by the extruded portion 15b ₁ and the hole 15b _2, and the extruded portion 15c ₁ and the hole 15c ₂ , respectively. ， It is not limited to this. On the other hand, each of the hall elements 16A to 16C includes a hall element fixing hole 1a provided at a predetermined position of the circuit board 1 and a circuit board as shown in FIGS. 2, 4A and 4B. The pattern land 1b provided on the back surface of the No. 1 is fixed by imposing an imposition using the hole element lead terminal portion 16d. In the illustrated example, four pattern lands 1b and lead terminal portions 16d are electrically contacted. By inserting and arranging the imposition component on the back surface of the circuit board 1 and the discrete component from the surface, all the soldering is done on the back surface side, so that the circuit board 1 is configured as a single-sided board.

Since the present embodiment is applied to a three-phase brushless motor, three hall elements 16A, 1 are used.
6B and 16C are arranged on the circuit board 1,
The respective hall elements 16A to 16C may be arranged so that the directions of the hall elements are parallel to the soldering direction when soldering to the circuit board 1 so that the arrangement work and the soldering work can be easily performed. . In this respect, the conventional hole elements 16a to 16
In the case of c, it is a simplification of the troublesome arrangement work of arranging the centers of the magnetic poles 5a of the rotor magnet 5 toward the inner circumference. As a result, as shown in FIG. 2, the central angle θ formed by the center line L of the generator coil portion 15 and the center line L ′ of each of the hall elements 16A to 16C as shown in FIG.
Is approximately 90 ° to 180 ° (about 135 in FIG. 2)
As an example), the layout has a design margin in the radial and circumferential directions. This means that the frequency generator coil unit 15 is prepared as one electronic component, so that it is possible to realize a single-sided board and further the iron board 15f.
Since (Fig. 3) functions as a back yoke and increases the output of the generator, the coil pattern is almost 36
The one that covers the entire circumference of 0 ° is its 1/2 to 1/4 (180
Since it was possible to reduce the angle to 90 °) and to form a fan-shaped structure, the space of the generator coil portion 15 on the circuit board was reduced.
It is possible to significantly reduce the amount of space. This space saving has hitherto been a design constraint on the arrangement of the hall elements, but at least the margin for arranging in the remaining space on the circumference can be greatly expanded.

FIG. 5 shows the shape of the rotor magnet flange, the magnetization of the rotor magnet magnetic pole, the magnetization of the frequency generator magnet, and the method of detecting each magnetic pole, so that they can be compared with the conventional one shown in FIG. It is shown in. That is, in the conventional type, as shown in FIG.
The frequency generator magnet 4 provided at the tip of the rotor is the frequency generator magnetic pole portion 4a of the flange portion of the rotor magnet 5.
And the magnetic pole detecting magnetic pole portion 4b of the motor magnet corresponding to this base portion.
b and the frequency generator magnetic pole portion 4a are parallelly magnetized in the axial direction (the directions of magnetization are B and C directions respectively), and the magnetization A of the rotor magnet magnetic pole is not directly detected but the magnetization B is rotated. -The magnetic poles of the tamagnets are detected by the magnetization C to detect the magnetic poles of the frequency generator. On the other hand, in the first embodiment of the present invention, the step portion 4c is provided in a part of the frequency generator magnet 4 of FIG. 5, and the frequency generator coil pattern 15a immediately below the frequency generator magnetic pole portion 4a is provided. (Fig. 2) speed detection is performed, and the radial magnetization A of the rotor magnet 5 is detected.
The leakage magnetic flux A '(the direction perpendicular to the magnetization A) of the magnetic pole portion 5a magnetized by means of the stepped portion 4c is detected by the surface-mounted hall elements 16A to 16C shown in FIG.
Therefore, the frequency generator magnetic pole portion 4a and the leakage magnetic flux A'of the magnetic pole portion 5a of the rotor magnet 5 can be detected without receiving any magnetic interference with each other. Therefore, in the present embodiment, as in the conventional method,
In order to detect the magnetic pole portion 5a separately from the magnetic pole portion 5a of the tamagnet 5, it is no longer necessary to provide an auxiliary magnetic pole portion for detection such as the magnetic pole portion 4b for magnetic pole detection.

Second Embodiment: FIGS. 6 to 8 are explanatory views showing a second embodiment of the present invention. FIG. 6 is a vertical sectional front view of a main part, and as shown in the figure, a groove 4d is provided at a substantially central portion of the frequency generator magnet 4 provided at the tip of the rotor magnet 5, and the structure thereof is shown. There are features. FIG. 7 is an enlarged view showing the shapes of the magnets 4 and 5 and the groove 4d, the magnetized state of the magnetic poles, and the leakage magnetic flux in this embodiment rotated by 90 °. As shown in FIG. Magnet 5
The leakage flux A'caused by the magnetization A of the magnetic pole portion 5a of
Although the magnetic pole portion 5a of the tamagnet 5 is detected, it is shown that these detections can be performed without magnetic interference with each other. Figure 8
Is an example in which the central angle θ ′ between the center M of the generator coil portion 15 ′ and the center M ′ of the hall elements 16A to 16C is about 90 ° in the present embodiment, and at least the frequency generator coil portion 1
It is shown that the space between 5'and the hall elements 16A to 16C is about half of the conventional one. In each of the above-described embodiments, the magnet for the frequency generator is integrally formed on the brim portion that abuts on the tip of the rotor magnet, and the required magnetization is performed to form the magnetic pole. It goes without saying that it is also possible to integrally combine a separate body from the rotor magnet.

[0012]

Since the DC brushless motor to which the present invention is applied has the above-mentioned structure, it has the following excellent effects. Since the frequency generator coil section was prepared as one electronic component, a single-sided board could be realized. Since the frequency generator coil part is formed on the substrate of high magnetic permeability material such as iron substrate, the output can be increased, and the generator coil can be reduced to 1/2 to 1/4 of the circumferential area compared to the conventional one.
Further, when the coil pattern was formed in a fan shape, the generator coil could be made more compact. Since a step or groove is provided in a part of the frequency generator magnet provided at the tip of the rotor magnet, the detection of the magnetic pole of the rotor magnet is performed in the magnetizing direction of the inner circumference of the rotor magnet. And the leakage magnetic flux in the direction of the C axis perpendicular to
Since it can be detected by the faced hall element, it is not necessary to provide the same number of magnetic poles for magnetic pole detection as the rotor magnet as in the conventional case, and magnetic interference with the frequency generator magnetic pole is eliminated. I was able to prevent it. Providing a step or groove on the frequency generator magnet,
Due to the combined effect of being able to directly detect the leakage magnetic flux of the rotor magnet magnetic pole with a faced hall element without magnetic interference, it is possible to design the layout of the frequency generator coil section and the hall element. We were able to greatly increase the margin.

[Brief description of drawings]

FIG. 1 is a half-section vertical front view showing an embodiment of the basic configuration of a DC brushless motor to which the present invention is applied.

FIG. 2 is a front view (left side view in FIG. 1) of the circuit board in which the frequency generator coil unit and the hall element unit are assembled in the first embodiment of the present invention.

FIG. 3 is a vertical cross-sectional front view of a circuit in which the frequency generator coil unit of FIG. 2 is mainly assembled.

4A and 4B show a circuit in which the hall element portion of FIG. 2 is assembled. FIG. 4A is a vertical sectional front view and FIG. 4B is a bottom view thereof.

FIG. 5 is an enlarged view of the essential parts showing the shapes of magnets 4 and 5 in FIG. 1 as the first embodiment of the present invention, the magnetized states of the magnetic poles, and the leakage flux, which are rotated by 90 °.

FIG. 6 is a vertical sectional front view of a half portion showing a second embodiment of the present invention.

FIG. 7 shows a magnet 4 in the second embodiment shown in FIG.
The main part showing the shape of FIG.
It is the enlarged view rotated and shown.

FIG. 8 is a front view of a circuit board showing a third embodiment of the present invention, which is conventionally required by setting a central angle θ ′ to about 90 ° by a combination arrangement of a frequency generator section and a hall element group. The circuit board area is reduced to about 1/2.

FIG. 9 is a vertical sectional front view of a half portion of a DC brushless motor including a conventional frequency generator section and a magnetic pole detection section.

FIG. 10 is a view showing the shapes of the rotor magnet 5 and the frequency generator magnet 4 shown in FIG.
It is the enlarged view shown by rotating 0 degree.

11 is a coil pattern and ho of the circuit board 1 of FIG.
It is a front view showing an example of arrangement of the rule element.

[Explanation of symbols]

1: Circuit board 3: Rotor 4: Frequency generator magnet 4a: Frequency generator magnetic pole portion 4c: Step portion 4d: Groove portion 5: Rotor magnet 15: Frequency generator coil portion 15a: Coil pattern 16A to 16C, 16: Imposition hole element (hole element)

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Masaru Minagawa 3-93 Aioi-cho, Kiryu-shi, Gunma Japan Servo Co., Ltd. Kiryu Plant

Claims (4)

[Claims] 1. A rotor in which a magnet for a frequency generator and a rotor magnet are integrally formed, the rotor having a stator having a winding facing the rotor and the rotor.
In a DC brushless motor, a mounting bracket that supports the rotating shaft, bearings, etc., and a circuit board equipped with a control and drive circuit are placed in the axial gap between this rotor and the stator.
A step portion or a groove portion is provided in a part of the frequency generator magnet, and an imposition hall element is arranged on the circuit board as a magnetic pole detection portion of the rotor magnet. DC brushless motor, characterized in that the machine coil is fixed by soldering as a modularized electronic component, and the frequency generator coil is arranged on a high magnetic permeability material such as an iron substrate. Ta. 2. The DC brushless motor according to claim 1, wherein the frequency generator coil portion is formed into a fan shape as a whole including the coil pattern of the frequency generator. 3. The imposition hall element according to claim 1, wherein the imposition hole element is fixed to the pattern land of the circuit board by soldering to the lead terminal portion thereof. DC brushless motor. 4. The center of the imposition hall element and the center of the frequency generator coil section are arranged at least 90 ° to 180 ° apart from each other about the axis of rotation. The DC brushless motor according to any one of 1.