JP4871673B2 - DC brushless motor cooling structure - Google Patents

Description

  The present invention relates to a stator cooling structure mainly in a DC brushless motor suitable as a drive source for an electric power tool such as an impact driver.

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 Since the electric circuit board for rotating the rotor by sequentially supplying current to each drive coil of the child is provided, and no brush and commutator are required, the device can be made compact and maintenance-free.
In such a DC brushless motor, it is necessary to cool the heat generated by energizing the drive coil or the like in order to prevent malfunction of the sensor substrate. Conventionally, a technique for cooling a drive coil in a DC brushless motor is disclosed in, for example, Japanese Patent Application Laid-Open No. 2004-274800. This conventional cooling structure is configured to allow the outside air introduced by the cooling fan to flow between adjacent drive coils of the stator. According to such a conventional structure, the drive coil and its periphery are efficiently cooled to provide a sensor substrate. Such malfunctions can be prevented in advance.
JP 2004-274800 A

  However, according to the above-described conventional cooling structure, although the cooling effect can be enhanced on the surface side of the wound drive coil, the inside of the drive coil and the stator core may still be insufficiently cooled. . It is an object of the present invention to enable more efficient cooling of these.

Said subject is solved by each following invention.
1st invention is the cooling structure of the stator of a DC brushless motor, Comprising: A stator has a some cylindrical part and the several tooth part which protrudes in the radial direction center side from the internal peripheral surface of a cylindrical part. An electric insulation member is provided that covers the iron core and the inner peripheral surface of the cylindrical portion and covers the range excluding the tip end surface of the tooth portion, and is wound around the range covered with the electric insulation member of each tooth portion and is driven coil Is a cooling structure in which an exposed portion that is not covered with an electrical insulating member is provided on the inner peripheral surface of the cylindrical portion within a range in which the winding does not contact between adjacent drive coils.
According to the first aspect of the present invention , the exposed portion that is not covered with the electrical insulating member is provided between the adjacent drive coils on the inner peripheral side of the cylindrical portion, and the stator core is exposed. The stator core is cooled more efficiently.
2nd invention is a cooling structure of the stator of a DC brushless motor, Comprising: A stator has a some cylindrical part and the several tooth part which protrudes in the radial direction center side from the internal peripheral surface of a cylindrical part. An electric insulation member is provided that covers the iron core and the inner peripheral surface of the cylindrical portion and covers the range excluding the tip end surface of the tooth portion, and is wound around the range covered with the electric insulation member of each tooth portion and is driven coil The cooling structure is provided with a ventilation groove that is not covered with the electrical insulating member from the base side to the tip side of the tooth portion in a range where the winding does not contact in the drive coil.
According to the second aspect of the invention , the cooling air flows from the base part of the drive coil to the tip part through the ventilation groove not covered with the electrical insulating member, whereby the tooth part and the winding are efficiently cooled.

Next, although not included in the invention described in the scope of claims, an embodiment (first embodiment) of the first invention will be described based on FIGS. 1 to 6 as a related invention . FIG. 1 shows a DC brushless motor 10 according to the first 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. A sensor board 30 including three magnetic sensors 31 to 31 for detection and an electric control board having 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, six tooth portions 21 a to 21 a are provided in a state of projecting 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 configured by being wound around a portion of each tooth portion 21 a covered with the electrical insulating member 22. In the drawing, reference numeral 23a is attached to the winding portion. 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 sensor substrate 30 is fixed without rattling in the plate thickness direction by engaging claws 22 a to 22 a provided integrally with the electrical insulating member 22. Further, the sensor substrate 30 is also appropriately positioned with respect to the position around the axis line J by positioning protrusions (not shown).

The DC brushless motor 10 according to the first embodiment is mainly characterized by the cooling structure of the stator 20. FIG. 2 shows the stator 20 alone. As described above, the inner peripheral surface of the stator core 21 and the six tooth portions 21 a to 21 a are covered with the electrical insulating member 22. The drive coil 23 is configured by being wound around a range covered with the electrical insulating member of each tooth portion 21a. As a result that the inner peripheral surface of the stator core 21 is not covered with the electrical insulating member 22 in a range where the winding portion 23a of each drive coil 23 is not in contact (a range not covered with the winding portion 23a), Exposed portions 21b to 21b in which the stator core 21 is exposed are provided. Each exposed portion 21b is provided with a relatively small width from the front end in the axis J direction of the stator core 21 to the rear end. The exposed portion 21b has a comparatively small width and is equivalent to a configuration in which the electric insulating member is omitted from the front end to the rear end in the axis J direction of the stator core 21.

According to the cooling structure configured as described above, a part of the inner peripheral side of the stator core 21 is exposed in a range where the winding portion 23a of the drive coil 23 does not contact (a range that does not affect the magnetic field). Yes. For this reason, when the cooling fan 17 rotates integrally with the rotor 11, outside air is introduced into the housing of the electric tool, and this is blown against the rotor 11, the stator 20, etc., and a part thereof is exposed to the exposed portion. Directly sprayed on 21b-21b. For this reason, compared with the case where the inner peripheral surface of the stator 20 is entirely covered with the electrical insulating member 22, the stator core 21 and thus the stator 20 can be cooled more efficiently.
The first embodiment illustrated above can be implemented with various modifications. For example, although the configuration in which the exposed portions 21b to 21b are provided at a total of six locations between the adjacent drive coils 23 and 23 is illustrated, the number may be reduced to 1 to 5 locations. Moreover, although each exposed part 21b illustrated the structure provided continuously in the whole range of the axis line J direction from the front end of the stator core 21 to the rear end, you may provide intermittently or partially.

Furthermore, in 1st Embodiment demonstrated above, it was set as the structure which raises the cooling effect of the said stator core 21 by providing the exposed parts 21b-21b in the internal peripheral surface of the stator core 21, but for example, FIG. As shown in FIGS. 4 to 6, by providing the drive coil 43 with a ventilation groove, the cooling effect of the tooth portions 41a to 41a and the windings can be mainly enhanced. The illustrated first embodiment is an embodiment according to the first invention that is not included in the invention described in the claims , and the second embodiment described below is the invention described in the claims (first 2) .
The exposed portion of the stator core 21 is different between the first embodiment and the second embodiment. The description of components and members that do not need to be changed is omitted by using the same reference numerals.
The stator 40 of the second embodiment includes a stator core 41 having a substantially cylindrical shape and an electrical insulating member 42 covering the stator core 41. On the inner peripheral side of the stator core 41, tooth portions 41a to 41a extending toward the radial center side are provided at six equal positions in the circumferential direction, as in the first embodiment. A range excluding the tip surface of each tooth portion 41a and the outer peripheral surface of the stator core is covered with an electrical insulating member 42. The drive coil 43 is configured by being wound around a range covered with the electrical insulating member 2 of each tooth portion 41a to 41a. In the drawing, reference numeral 43a is attached to the winding portion.
Each tooth portion 41a is covered with an electrical insulating member 42 except for its tip surface. However, ventilation grooves 42 a and 42 a that are not covered with the electrical insulating member 42 are provided on the front end face and the rear end face. Each ventilation groove 42a is set to a width dimension sufficiently smaller than the width of the tooth portion 41a, and the winding portion 43a of the tooth portion 41a does not come into contact with the stator core 41 (tooth portion 41a). Yes.
The inner peripheral end of each ventilation groove 42a is opened toward the rotor 11 side. The outer peripheral side end of each ventilation groove 42a reaches the outer peripheral side end of the winding part 43a.

According to the cooling structure of the second embodiment described above, outside air is introduced into the housing of the electric tool by rotating the cooling fan 17 integrally with the rotor 11, and this is blown onto the rotor 11, the stator 20, and the like. As a result, a part of the air flows in the ventilation groove 42a provided in each drive coil 43, so that each wire of the winding portion 43a can be more surely combined with the cooling air flowing on the surface side of the winding portion 43a. Can be cooled. Moreover, since the winding part 43a can be cooled from the inside and the tooth part 41a of the stator core 41 can be directly cooled, the drive coil 43 and thus the stator 40 can be more effectively cooled. .
The embodiment exemplified above can be further modified. For example, although the configuration in which the ventilation grooves 42a and 42a are provided on both the front side and the rear side of the tooth portion 41a is illustrated, a configuration in which a ventilation path is provided in only one of them may be employed.
In addition, the stator can be cooled more effectively by combining the cooling structure of the first embodiment and the cooling structure of the second embodiment.
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.

It is a longitudinal sectional view of the DC brushless motor according to the first embodiment. It is a front view of the stator single-piece | unit provided with the cooling structure of 1st Embodiment. FIG. 3 is a cross-sectional view taken along the line (3)-(3) in FIG. It is a front view of the stator single-piece | unit provided with the cooling structure of 2nd Embodiment. FIG. 5 is a cross-sectional view taken along line (5)-(5) in FIG. 4 and is a longitudinal cross-sectional view of the front portion of the stator. FIG. 6 is a sectional view taken along line (6)-(6) in FIG. 5 and is a longitudinal sectional view of a drive coil.

DESCRIPTION OF SYMBOLS 10 ... DC brushless motor 11 ... Rotor 12 ... Rotor core J ... Rotating axis 13 ... Ring magnet 14 ... Rotating axis 15, 16 ... Bearing 17 ... Cooling fan 20 ... Stator (1st Embodiment)
DESCRIPTION OF SYMBOLS 21 ... Stator iron core, 21a ... Tooth part 22 ... Electrical insulation member, 22a ... Engagement claw 23 ... Drive coil 30 ... Sensor substrate 31 ... Magnetic sensor (Hall element)
40. Stator (second embodiment)
41 ... Stator core, 41a ... Tooth part 42 ... Electrical insulation member, 42a ... Ventilation groove 43 ... Drive coil, 43a ... Winding part

Claims (1)

A stator brush cooling structure of a DC brushless motor, wherein the stator includes a cylindrical core portion and a stator core having a plurality of teeth protruding from the inner peripheral surface of the cylindrical portion toward the center in the radial direction, An electric insulating member that covers the inner peripheral surface of the cylindrical portion and covers the range excluding the tip end surface of the tooth portion , and is wound around the range covered by the electric insulating member of each tooth portion and is driven by the drive coil Is configured,
The cooling structure which provided the ventilation groove which is not covered with the said electrical insulation member from the base side of the said tooth | gear part to the front end side in the range which a winding does not contact in the said drive coil.

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