JP5512781B2 - Electric tool having a DC brushless motor - Google Patents

Description

This invention relates to an electric tool having a D C brushless motor.

In this DC brushless motor, a rotor having a magnet (permanent magnet) attached to a rotor core having a laminated steel plate structure and a drive coil wound around each tooth portion of the stator core having a laminated steel plate structure are arranged around the rotor. , A sensor substrate having a magnetic sensor (Hall element) for detecting the position of the magnetic pole of the rotor, and the position of the magnetic pole of the rotor detected by this sensor substrate, and fixing based on this flowing sequentially current to the drive coils of the child is provided with electrothermal circuit board to rotate the rotor, Ru can be made compact and maintenance-free equipment because it does not require a brush and a commutator.
As the brushless motor of traditional, for example, Japanese Patent No. 3545215 No. technique disclosed in Japanese has become known.

Japanese Patent No. 3545215

An object of this invention is to provide the electric tool which has DC brushless motor which can attach a sensor board | substrate .

For this reason, the present invention has the following structure.
1st invention is arrange | positioned at the inner peripheral side of the stator core, the electric insulation member which covers at least one part of the said stator core, the drive coil wound around the said electric insulation member, and the said stator core A rotor core, a magnet fixed to the rotor core, a rotating shaft fixed to the rotor core and having one end and the other end, and a cooling fan disposed on the one end side of the rotor core One end side bearing which is disposed on the one end side of the cooling fan and rotatably supports the rotating shaft, and the other end which is disposed on the other end side of the rotor core and rotatably supports the rotating shaft. A DC brushless motor having a side bearing, a sensor substrate disposed on the other end side of the drive coil and fixed to the insulating member, and a magnetic sensor attached to the one end side surface of the sensor substrate is driven. Built-in as a source A power tool having a housing, wherein the sensor board is attached by screwing in a state where the sensor board is positioned by the electrical insulating member, and the cooling fan is opposed to the drive coil. The sensor substrate is disposed on the other end side of the drive coil so as to face the drive coil, the sensor substrate has a hole, and the diameter of the hole Is formed larger than the diameter of the other end side bearing, and at least a part of the one end side surface of the stator core is exposed from the electric insulating member, and the cooling fan rotates. The electric tool is characterized in that outside air is introduced into the housing, and the rotor and the stator are cooled by the outside air.

It is a longitudinal cross-sectional view of the DC brushless motor which concerns on embodiment of this invention. FIG. 2 is a front view of the DC brushless motor, as viewed from (2) in FIG. 1. It is the (3) part enlarged view of FIG. 1, Comprising: It is a longitudinal cross-sectional view which shows the engagement state of the engaging claw with respect to a sensor board | substrate. It is an enlarged side view of a nail | claw part. It is an expansion perspective view of the nail | claw part of an engagement nail | claw. FIG. 6 is a cross-sectional view taken along the line (6)-(6) in FIG.

Next, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a DC brushless motor 10 according to the present embodiment. The DC brushless motor 10 is a motor having a four-pole structure, and includes a rotor (rotor) 11, a stator (stator) 20 that positions the rotor 11 on the inner peripheral side, and positions of magnetic poles of the rotor 11. The sensor board | substrate 30 provided with the three Hall elements 31-31 for detection and the electric control board | substrate which has a drive circuit are provided. Illustration of the electric control board is omitted.
The rotor 11 includes a rotor core 12 in which a large number of circular thin steel plates are stacked. Around the rotor core 12, four-pole ring magnets 13 to 13 are fixed. A rotating shaft 14 is fixed to the center of the rotor core 12.
The rotating shaft 14 protrudes from both sides of the rotor core 12. The rotating shaft 14 is supported by a housing (not shown) of an electric tool in which the DC brushless motor 10 is housed so as to be rotatable around an axis J through bearings 15 and 16. Hereinafter, the rotation axis J direction of the rotor 14 is also referred to as the machine tool length direction. A cooling fan 17 is attached on the left side of the rotating shaft 14 between the rotor core 12 and the bearing 16. The cooling fan 17 rotates integrally with the rotor 11. As the cooling fan 17 rotates, outside air is introduced into the housing of the electric tool, and the rotor 11 and the stator 20 are cooled by the outside air (motor cooling air).
The stator 20 has a substantially cylindrical shape, and is made of a stator core 21 having a laminated steel plate structure in which a large number of thin steel plates are laminated, and a synthetic resin called an insulator that electrically insulates the stator core 21. An electrical insulating member 22 is provided. On the inner peripheral side of the stator core 21, a plurality (six in this example) of tooth portions 21 a to 21 a are provided in a state of protruding from the circumferentially equally divided position toward the radial center.
A range excluding the outer peripheral surface of the stator core 21 and the tip surfaces of the tooth portions 21 a to 21 a is covered with an electrical insulating member 22. A drive coil 23 is wound around a portion of each tooth portion 21 a covered with the electrical insulating member 22. The distal end surface of each tooth portion 21 a that is not covered by the electrical insulating member 22 is located in a state where a certain gap is provided between the distal end surface and the peripheral surface of the rotor 11.

A sensor substrate 30 is attached to the front surface (right end surface in FIG. 1) of the electrical insulating member 22. The present embodiment is characterized by a structure for attaching the sensor substrate 30 to the electrical insulating member 22 and thus to the stator 20. On the front side of the electrical insulating member 22, a substantially circular step portion 22a is provided over the entire circumference. The sensor substrate 30 is accommodated in the stepped portion 22a and positioned in the surface direction.
The sensor substrate 30 has a substantially disk shape, and an escape hole 30a for positioning the rotation shaft 14 of the rotor 11 is provided at the center thereof. Further, a terminal connection plate portion 30b for wiring connection is provided in a state of projecting in the radial direction below the sensor substrate 30. The terminal connecting plate portion 30b extends to the outer peripheral side (downward in FIGS. 1 and 2) of the electrical insulating member 22 through a cutout portion 22b in which a part of the stepped portion 22a is cut out.
The three magnetic sensors 31 to 31 attached to the sensor substrate 30 are sensors for detecting which position of the magnetic pole of the rotor 11 is opposed to which tooth portion 21a of the stator 20. In the example, a Hall element is used. As shown in FIG. 2, the sensor substrate 30 is positioned and fixed by three engagement claws 32 to 32 that are provided at three equal positions around the electrical insulating member 22. Each engaging claw 32 has the same configuration. Details of the engaging claw 32 are shown in FIGS.

As shown in FIG. 3, the three engaging claws 32 to 32 are integrally provided so as to protrude from the outer peripheral side of the stepped portion 22 a of the electrical insulating member 22 to the front side in the longitudinal direction (rightward in FIGS. 1 and 3). As shown by a two-dot chain line in FIG. 3, each is provided so as to be elastically deformable so as to bend outward in the radial direction as a whole. As shown in FIG. 4, each engaging claw 32 includes an engaging arm portion 32 e extending from the peripheral portion of the electrical insulating member 22 to the front in the machine length direction, and a claw protruding radially inward from the distal end portion of the engaging arm portion 32 e. A portion 32a is provided.
Each engagement arm portion 32e has a flat plate shape with a rectangular cross section. Each claw portion 32a has a guide surface 32d on the front surface side and an engagement surface 32b on the rear surface side. The guide surface 32d is inclined in a direction in which the front end side (lower side in FIG. 3) is displaced rearward with respect to the machine direction (rotation axis J of the rotary shaft 14). On the other hand, the engagement surface 32b is inclined in a direction that displaces the front end side (lower side in FIG. 3) to the front side (right side in FIG. 3) with respect to the machine direction (rotation axis J of the rotary shaft 14).
Further, a detent protrusion 32c having a triangular cross section is integrally provided inside each engagement arm 32e. Each rotation prevention protrusion 32c is formed in the range from the base part to the engaging surface 32d of the nail | claw part 32a along the length direction. Engagement recesses 30a to 30a are formed at the three-peripheral positions of the sensor substrate 30 corresponding to the rotation stop protrusions 32c. The sensor substrate 30 is positioned (rotated) around the rotation axis J of the rotation shaft 14 by the state where the rotation protrusion 32c of the engagement claw 32 is fitted in each engagement recess 30a.

  According to the attachment structure of the sensor substrate 30 configured as described above, when attaching the sensor substrate 30 to the front end surface of the electrical insulating member 22, the peripheral portion of the sensor substrate 30 is formed by the three engagement claws 32 to 32. If the sensor substrate 30 is pushed in while being brought into contact with each guide surface 32d and bent in the radial direction against the elastic force of each engagement claw 32, the sensor substrate 30 is mounted in the stepped portion 22a. be able to. In this attached state, the engagement surfaces 32b of the three engagement claws 32 to 32 are pressed against the edge of the sensor substrate 30 by the elastic force of the engagement arm portion 32e. For this reason, the elastic force of the three engagement arm portions 32e to 32e is in the plate thickness direction due to the tilting action of the engagement surface 32b, and the sensor substrate 30 is attached to the front end surface of the electrical insulating member 22. This acts in the direction of pressing against the bottom of the stepped portion 22a (the direction indicated by the white arrow in FIG. 3). As described above, the sensor substrate 30 is assembled in a state in which the engagement surface 32b of each engagement claw 32 is constantly pressed to the edge thereof and is pressed against the stepped portion 22a. It can be installed without any sticking.

Further, even if there is some variation in the thickness of the sensor substrate 30, each engagement arm portion 32 e is elastically deformed radially outward and the engagement surfaces 32 b to 32 b are pressed against the edge of the sensor substrate 30. As long as the sensor substrate 30 is held in a state of being pressed in the plate thickness direction by the elastic force of the engagement arm portions 32e to 32e, the sensor substrate 30 can be attached in a state where there is no backlash in the plate thickness direction.
Further, the engagement arm portion 32e of each engagement claw 32 is provided with a detent projection 32c, and each detent projection 32c is fitted into the engagement recess 30a in the attached state of the sensor substrate 30, Thereby, the rotation of the sensor substrate 30 is prevented. As described above, the engaging claws 32 to 32 provided at the three-way positions in the circumferential direction have two functions, that is, a positioning function in the thickness direction of the attached sensor substrate 30 and a positioning (rotation prevention) function around the rotation axis J. I have. Therefore, each mechanism can be efficiently arranged in a limited space called the end face of the electrical insulating member as compared with the case where they are provided separately.
Also, if the sensor board is pressed against the stepped portion 22a while spreading the three engaging claws 32 to 32 outward in the radial direction, the mounting is completed. It is possible to speed up the assembly process of the sensor substrate.

The embodiment described above can be implemented with various modifications. For example, the anti-rotation protrusion 32c of each engagement claw 32 has a configuration having a triangular cross-section, but other anti-rotation protrusions having a cross-sectional arc shape and a rectangular cross-section may be used. Further, the detent protrusion 32c of each engagement claw 32 may be omitted.
Moreover, although the structure which provides an engagement nail | claw in the trisection position of the circumferential direction was illustrated, four or more places may be sufficient.
Furthermore, it is good also as a structure which attaches the said sensor board | substrate using screwing and adhesion | attachment together in the illustrated attachment structure.
Moreover, although the case where the sensor substrate is attached to the front side of the stator is illustrated, the present invention can be similarly applied to the case where it is attached to the rear side.
The cooling fan 17 can be applied to the same cooling structure even if the cooling fan 17 is arranged on the front side in addition to the arrangement arranged on the rear side of the rotor.
Furthermore, although the DC brushless motor incorporated as a drive source of an electric tool was illustrated, it can apply similarly to what is used as a drive source of other apparatuses.

DESCRIPTION OF SYMBOLS 10 ... DC brushless motor 11 ... Rotor 12 ... Rotor core J ... Rotating axis 13 ... Ring magnet 14 ... Rotating shafts 15, 16 ... Bearing 17 ... Cooling fan 20 ... Stator 21 ... Stator iron core, 21a ... Tooth part 22 ... Electrically insulating member, 22a ... Step part, 22b ... Notch part 23 ... Drive coil 30 ... Sensor substrate, 30a ... Release hole, 30b ... Terminal connection plate part 31 ... Magnetic sensor (Hall element)
32 ... engaging claw 32a ... claw part, 32b ... engaging surface, 32c ... detent protrusion, 32d ... guide surface 32e ... engaging arm part

Claims (1)

A stator core,
An electrically insulating member covering at least a part of the stator core;
A drive coil wound around the electrically insulating member;
A rotor core disposed on the inner peripheral side of the stator core;
A magnet fixed to the rotor core;
A rotating shaft fixed to the rotor core and having one end and the other end;
A cooling fan disposed on the one end side of the rotor core;
One end side bearing disposed on the one end side of the cooling fan and rotatably supporting the rotating shaft;
The other end side bearing which is disposed on the other end side of the rotor core and supports the rotating shaft rotatably;
A sensor substrate disposed on the other end side of the drive coil and fixed to the electrical insulating member;
A magnetic sensor attached to the surface of the one end side of the sensor substrate;
DC brushless motor with a built-in drive source,
An electric tool having a housing,
The electrical insulating member is provided with a stepped portion capable of positioning the sensor substrate in the surface direction and the rotational direction, and a plurality of stepped portions are disposed on the outer peripheral side of the stepped portion so as to be located radially outside the sensor substrate. And a cutout portion formed by cutting out a part of the stepped portion , and the sensor substrate has a projecting portion that projects radially outward from the cutout portion. ,
The sensor substrate is attached in a state where the sensor substrate is positioned by the electrical insulating member and pressed against the step portion using screwing together, and has a hole, and the diameter of the hole is that of the other end side bearing. Formed larger than the diameter,
The cooling fan is disposed on the one end side of the drive coil so as to face the drive coil, and the sensor substrate is disposed on the other end side of the drive coil so as to face the drive coil. And
At least a part of the end surface on the one end side of the stator core is exposed from the electrical insulating member,
When the cooling fan rotates, outside air is introduced into the housing, and the rotor and stator are cooled by the outside air.

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