JP3637265B2 - Position detection device and brushless motor equipped with the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a position detection device for a brushless motor, and more particularly to a mounting structure for attaching a position detection hall element to a printed circuit board.
[0002]
[Prior art]
Conventionally, in order to obtain rotor position information, a Hall element is attached to an SECC steel plate, and a rotor magnet moves on the Hall element to obtain a rotor position output. However, this method has a drawback in that the pattern is formed on the iron plate, so that processing is complicated and expensive.
In view of this, a proposal has been made in which a printed board such as a paper phenolic board is disposed on an iron plate and a pattern is formed on the printed board.
This will be described below with reference to the drawings. FIG. 2 is a cross-sectional view showing a position detecting device in which a printed board such as a paper phenol board is stacked on a conventional iron plate, a pattern is formed on the printed board, and a Hall element is mounted on the pattern. In the figure, 1 is an iron plate, 2 is a printed circuit board superimposed on the iron plate 1, 3 is a land connected to a pattern 20 formed on the printed circuit board 2, 4 is the land 3 and the pattern 20 Is a resist coating. Reference numeral 5 denotes a hall element, and 6 is a lead of the hall element 5, two for normal input and one for output are provided and fixed to the land 3 by soldering or the like. Reference numeral 7 denotes an element made of, for example, indium / antimony (InSb), gallium arsenide (GaAs) or the like, and is electrically connected to the corresponding lead 6 from the four corners by the bonding wire 8. Reference numeral 9 denotes a magnetic flux collecting plate made of ferrite or the like. Reference numeral 10 denotes a rotor magnet configured integrally with a rotor (not shown).
[0003]
[Problems to be solved by the invention]
The brushless motor position detection device configured as described above is inexpensive because the pattern is formed on the printed circuit board, but compared with the iron plate 1 with the position detection device mounted directly on the iron plate and the Hall element. Is increased by the thickness of the printed circuit board (about 0.8 mm), and the output of the Hall element is reduced by that amount. Accordingly, the brushless motor using the position detection device has a weak position detection output, so that it cannot avoid the disadvantage that the position information is difficult to recognize.
[0004]
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a position detection device that solves the above-described drawbacks and that has a simple structure and does not reduce the output of the Hall element. Furthermore, another object of the present invention is to provide a brushless motor that can easily recognize position information of a brushless motor using a position detection device using a Hall element.
[0005]
[Means for Solving the Problems]
According to the first aspect of the present invention, in a position detection device in which a printed circuit board having a pattern formed on an iron plate is overlaid and a Hall element is mounted on the pattern on the printed circuit board, a through hole is formed in the printed circuit board. This is achieved by forming a half-cut protrusion on the iron plate, inserting the protrusion into a through-hole, arranging the iron plate and the hall element close to each other, and picking up a large amount of magnetic flux. it can. Further, according to the invention described in claim 2, this can be achieved by providing a brushless motor provided with the position detecting device described in claim 1.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a cross-sectional view showing a first embodiment of the present invention. In the figure, reference numeral 15 denotes a hall element. The Hall element 15 includes an element 17 made of indium / antimony (InSb), gallium arsenide (GaAs), indium / arsenic (InAs) silicon (Si), or the like at substantially the center. Reference numeral 16 denotes a lead of the hall element 15, and two for normal bias and one for output (16 a, 16 c, 16 b, and 16 d) are provided diagonally, and bonding wires 18 (18 a. 18c, 18b and 18d). A magnetic flux collecting plate 19 such as ferrite is provided close to the element 17. The element 17, the magnetic flux collecting plate 19, the bonding wire 18 and one end of the lead 16 are integrally molded with resin to constitute the Hall element 15. Reference numeral 12 denotes a printed circuit board such as a paper phenol plate in which a pattern 20 is formed on one surface and a through hole 12a is provided at a position where the Hall element 15 is mounted. Reference numeral 13 denotes a land provided at the tip of the pattern 20. On the land 13, the other end of the lead 16 (the leg of the hall element 15) is placed, fixed by soldering or the like, and electrically connected. When the lead 16 shown in FIG. 1 is a bias lead, the output lead is not shown because it is in a direction perpendicular to these leads. Reference numeral 14 denotes a resist for insulating the pattern 20 and the land 13. 11 is an iron plate provided under the printed circuit board 12, and a protrusion 11a is formed by half-cutting at a position corresponding to the through hole, and the tip of the protrusion 11a is in contact with the lower surface of the Hall element 15 or It is close. Reference numeral 10 denotes a rotor magnet disposed facing the Hall element 15 with a slight gap.
[0007]
As described above, in the present embodiment, by providing the through hole 12a in the printed circuit board 12, the printed circuit board 12 is placed on the iron plate 11, but the bottom surface of the Hall element 15 is directly on the bottom surface. Since the protrusion 11a of the iron plate 11 comes, the output of the Hall element 15 does not decrease. For this reason, an inexpensive brushless motor can be provided.
[0008]
【The invention's effect】
As described above, according to the present invention, in a position detection device in which a printed board having a pattern formed on an iron plate is overlaid and a Hall element is mounted on the pattern on the printed board, the iron plate is half-punched. By forming a protrusion and providing a through hole in the printed circuit board, and inserting the protrusion of the iron plate into this through hole, the protrusion and the Hall element are placed close to each other, It is possible to provide a position detection device that is inexpensive and does not reduce the output of the Hall element 15 even though the printed circuit board is mounted. Therefore, a brushless motor using such a position detection device has an effect of easily recognizing position information.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a first embodiment of the present invention.
FIG. 2 is a cross-sectional view showing a conventional position detection device.
[Explanation of symbols]
1,11 Iron plate 2,12 Printed circuit board 3,13 Land 4,14 Resist 5,15 Hall element 6,16 Lead 7,17 Element 8,18 Bonding wire 9,19 Magnetic flux collecting plate 10 Rotor magnet

Claims (2)

  In a position detection device in which a printed circuit board having a pattern formed on an iron plate is overlaid and a Hall element is mounted on the pattern on the printed circuit board, a through hole is provided in the printed circuit board, and a half-extruded protrusion on the iron plate A position detecting device in a brushless motor in which the protrusion is inserted into a through hole, the iron plate and the Hall element are arranged close to each other, and a large amount of magnetic flux can be picked up.   A brushless motor comprising the position detection device according to claim 1.

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