JPH04295263A - Brushless motor - Google Patents

Abstract

PURPOSE:To stabilize the operation of a Hall element and improve the heat radiation of electronic parts, using a lend frame for the connection of a driving circuit. CONSTITUTION:This is equipped with an electric circuit where Hall elements 17 and 18 are mounted on both sides of the metallic thin plate (lead frame) in the shape of circuit wiring, and an end bracket 22 made of synthetic resin, to which this electric circuit is fixed or which made in a body with this electric circuit. One part A of the lead frame 21 forms the connector to be connected with an external circuit. Since components are mounted on both sides, the Hall element can be disposed on the magnet side, and the operation becomes stable. Since a lead frame is used, it is excellent in heat radiation.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small brushless motor used in audio equipment, video equipment, etc.

0002

[Prior Art] In recent years, motors used in audio equipment, video equipment, etc. detect the rotational position of the rotor using a position detector such as a Hall element, instead of the conventional DC motor with brushes and a commutator. The drive transistors built into the integrated circuit connected in series with the multi-phase coils are sequentially turned on.
Brushless motors configured to rotate a rotor have been widely used because of their high reliability and long life.

FIG. 4 is a sectional view showing the structure of a conventional brushless motor. Reference numeral 2 denotes a rotor frame made of a magnetic material such as an iron plate, and a cylindrical permanent magnet 1 having a plurality of magnetic poles magnetized in the circumferential direction is fixed to the inside of the rotor frame, and a boss 13 is installed in the center of the rotor frame 2. The rotary shaft 3 is press-fitted through. Reference numeral 6 denotes an armature made of laminated silicon steel plates, etc., around which a drive coil 8 is wound with an insulating layer 14 in between. Further, a bearing housing 16 in which a first bearing member 9 that rotatably supports the rotor is press-fitted is attached to the inner diameter portion of the armature. Further, at the bottom of the stator, there is a Hall element 17 that detects the magnetic flux of the permanent magnet 1 of the rotor to detect the position of the rotor, and a signal from the Hall element 17 is detected to control energization of the drive coil. A circuit board 10 made of phenolic resin on which a drive IC and electronic components 18 are mounted is mounted, and the winding end of the drive coil 8 is soldered to the board through an insertion hole in the circuit board 10. The circuit board 10 also includes a connector 2 for electrical connection with the set-side circuit.
0 is installed. Further, a motor case 5 is provided with a second bearing member 4 that supports the rotor in the center thereof;
The motor is comprised of an iron plate end bracket 11 that fixes a bearing housing 16 to the motor case 5. Note that 15 is a thrust receiver.

0004

[Problems to be Solved by the Invention] However, when a conventional circuit board made of phenolic resin is used in the above configuration, the board warps due to the influence of temperature and humidity, and the gap between the Hall element and the permanent magnet increases. Sometimes the magnetic flux cannot be detected, causing problems such as the motor not rotating. Furthermore, the heat conductivity of the circuit board is poor and heat dissipation from the drive IC is not sufficient, resulting in deterioration of characteristics and, in severe cases, damage to the IC.

[0005] Furthermore, when a motor is installed in a set, it is often installed with the output shaft facing down and the end bracket facing up. Therefore, when using a single-sided board,
There was a copper foil surface on the end bracket side for ease of work such as connector installation. In that case, the Hall element was mounted on the opposite side of the substrate to the magnet as shown in FIG. 4, making it difficult to detect magnetic flux.

The present invention solves the above-mentioned problems, and has good heat dissipation, which reduces the temperature rise of electronic components such as drive ICs, and because it is a double-sided mounting type, the Hall element can be mounted on the magnet side to ensure stable operation. It is an object of the present invention to provide a brushless motor having an electric circuit configured to be less susceptible to the effects of temperature and humidity.

[0007]

[Means for Solving the Problems] In order to achieve the above object, the brushless motor of the present invention has Hall elements and drive ICs on both sides of a lead frame which is formed by plating a pressed thin metal plate in the shape of circuit wiring. It is also used as an end bracket for an electric circuit motor, which is made by mounting electronic components such as and hardening them with resin molding.

[0008]

[Function] As described above, by using a lead frame formed by pressing a metal plate, heat dissipation of the drive IC is improved, and warpage of the board caused by temperature and humidity is also reduced. In addition, since it is double-sided mounted, magnetic flux can be detected in close proximity by attaching the Hall element to the magnet side.
The operation of the Hall element becomes stable.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the brushless motor of the present invention will be described below with reference to FIGS. 1, 2, and 3.

FIG. 1 is a sectional view of a motor according to an embodiment of the present invention, and FIG. 2 is a plan view of an assembled electric circuit and armature of the present invention.
FIG. 3 shows a lead frame-shaped electrical circuit before the end bracket is integrally molded.

As shown in FIG. 3, the electric circuit of the brushless motor of the present invention includes a lead frame 21 formed by pressing a metal base material (for example, a copper plate) into the shape of circuit wiring;
After the double-sided plating process, the Hall element 17 is placed in the predetermined position.
Electronic components 18 such as a drive IC are mounted. At this time, the Hall element 17 is mounted on the side of the rotor facing the permanent magnets, and the electronic component 18 is also mounted on the back side of the rotor in order to rationalize space. Thereafter, the lead frame 21 and the electric circuit on which the components are mounted are integrally molded with synthetic resin, and the lead portions are cut. Incidentally, as shown in the figure, a large number of lead frames 21 are made in succession from a metal strip, and are punched out one by one by press working. The electrical circuit constructed in this manner constitutes the end bracket of the motor, as will be described later.

FIG. 1 shows an embodiment of the present invention incorporating the electric circuit described above, and 2 is a rotor frame made of a magnetic material such as an iron plate, inside which a plurality of magnetic poles are magnetized in the circumferential direction. A cylindrical permanent magnet 1 is fixedly attached to the rotor frame 2.
A rotary shaft 3 is press-fitted into the central portion of the rotary shaft 3 via a boss 13. Reference numeral 6 denotes an armature made of laminated silicon steel plates, etc., and a drive coil 8 is wound around the outer periphery of the armature with an insulating layer 14 in between. Further, a bearing housing 16 in which one bearing member 9 that rotatably supports the rotor is press-fitted is attached to the inner diameter portion of the armature. Further, a lead frame 21 is attached to the lower part of the stator, and the winding end of the drive coil 8 is wound around a connecting pin of the lead frame 21 as shown by a dotted line B and connected by soldering. FIG. 2 shows a front view of the assembled state of the stator and the electric circuit consisting of the lead frame, Hall element 17, and electronic component 18. Further, the terminal portion A of the lead frame 21 is molded as a connector for electrical connection with a set-side circuit. The electric circuit is fixed or molded integrally with an end bracket 22 that fixes the stator to the motor case 5.

[0013]

As is clear from the above description, the brushless motor of the present invention can stabilize position detection because the Hall element can be mounted facing the permanent magnet. Furthermore, since a lead frame is used for circuit connection, heat dissipation is good, and there is almost no warpage due to the effects of temperature and humidity. Furthermore, since it is mounted on both sides, a space-saving circuit can be constructed, and the motor can be made smaller. Further, electrical connection with the set-side circuit does not require a separate connector, and a part of the lead frame fulfills this role, which has a great effect on reducing assembly man-hours and costs.

[Brief explanation of the drawing]

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

[Figure 2] Assembly front view of the stator and electric circuit of the same brushless motor

[Figure 3] Diagram explaining lead frame manufacturing

[Figure 4] Cross-sectional view of a conventional brushless motor

[Explanation of symbols]

17 Hall element 18 Electronic component 21 Lead frame (circuit wiring-shaped thin metal plate) 22 End bracket A Connector

Claims (3)

[Claims] 1. A brushless motor comprising an electric circuit in which a Hall element and electronic components are mounted on both sides of a thin metal plate shaped like circuit wiring, and a synthetic resin end bracket to which the electric circuit is fixed. 2. The brushless motor according to claim 1, wherein the electric circuit and the end bracket are integrally molded by insert molding. 3. The brushless motor according to claim 1, wherein a part of the thin metal plate forms a connector for connecting the motor to a cassette side circuit.