WO2007142299A1

WO2007142299A1 - Brushless motor

Info

Publication number: WO2007142299A1
Application number: PCT/JP2007/061551
Authority: WO
Inventors: Kigen Agehara; Tomonori Ichiba
Original assignee: Max Co., Ltd.
Priority date: 2006-06-09
Filing date: 2007-06-07
Publication date: 2007-12-13
Also published as: CN101467335B; JP2007330076A; CN101467335A; TW200824230A; JP4857924B2

Abstract

In a brushless motor, (i) a switching element (10), which turns on and off energization of a coil (32) arranged on a stator (3), is adhesively fixed to a bottom outer surface of a bottomed cylindrical heat dissipating housing (1). (ii) A rotor (2) and a stator (3) are stored inside the heat dissipating housing (1), and a fixing section (16) for fixing a bearing (30) for the rotor (2) is arranged on the bottom inner surface. (iii) On an end portion on the side of the heat dissipating housing (1) of a rotating shaft (20) of the rotor (2), a cooling fan (22) for cooling the heat dissipating housing (1) is fixed. A storing recessed section (24) for storing the bearing (30) is formed at the center of the cooling fan (22).

Description

Specification

Brushless motor

Technical field

[0001] The present invention relates to a brushless motor, and more particularly to a brushless motor including a cooling fan that cools heat generated from a switching element.

Background art

Conventionally, in order to cool the heat generated by the switching element for turning on / off the current to the stator coil, the heat dissipating member is fixed to the stator core, and the heat generated by the switching element is applied to the heat dissipating member. There has been proposed a brushless motor in which a stator core has a function of a radiating fin by dissipating heat and dissipating heat to the stator core (for example, JP 2004-357371 A).

[0003] In the brushless motor described above, the switching element is fixed to the heat radiating member, and this heat radiating member is fixed to the stator core. Cooling by the cooling fan indirectly cools the switching element via the stator core and heat dissipation member. However, since the switching element is fixed in an upright state on the substrate, the overall length is not necessarily improved although the size is reduced.

Disclosure of the invention

[0004] One or more embodiments of the present invention can improve the cooling efficiency by directly cooling the switching element with a cooling fan, and can reduce the size by bringing the switching element into close contact with the heat dissipation housing. A brushless motor is provided.

According to a first aspect of the present invention, a brushless motor according to one or more embodiments of the present invention has the following requirements.

(i) The switching element for turning on / off the energization of the stator coil is tightly fixed to the bottom outer surface of the bottomed cylindrical heat radiating housing.

(ii) The rotor and the stator are accommodated inside the heat radiating housing, and a fixing portion for fixing a bearing that supports the rotating shaft of the rotor is provided on the inner surface of the bottom.

(iii) A cooling fan is fixed to the rotating shaft of the rotor, and the fixing fan is fixed to the center of the cooling fan. Provided a recess for receiving the fixed part

[0006] Further, according to a second aspect of the present invention, in the brushless motor according to one or more embodiments of the present invention, the heat radiating housing is formed of a metal excellent in heat conduction, and the fixed portion of the bearing is A plurality of engaging grooves are formed on the peripheral surface of the heat radiating housing from the opening side to the bottom side, and the outer peripheral surface of the stator is engaged with the engaging grooves. Preferably, convex pieces are formed.

[0007] According to the first aspect described above, the switching element is fixed in close contact with the heat radiating housing, and the cooling fan wind is blown directly onto the heat radiating housing, so that the cooling efficiency of the switching element is improved. In addition, since the rotor bearing is housed inside the cooling fan, the overall length of the brushless motor is shortened.

[0008] In addition, in a brushless motor (impact driver) that is now on the market, it functions as a bearing for a rotor that rotates on a pedestal force formed on the outer housing of the plastic. In such a conventional brushless motor, variations in the molding accuracy of the pedestal cannot be denied, and if the molding accuracy of the pedestal is poor, misalignment occurs, causing noise, and variations in the accuracy of molding of the pedestal are It was connected to the variation. However, according to the brushless motor of the second aspect described above, since the fixing portion of the rotor bearing is cut in the metal heat radiating housing, the accuracy of the fixing portion is increased and noise due to misalignment is generated. And variations in performance can be avoided.

[0009] Other features and advantages will be apparent from the description of the examples and the appended claims.

Brief Description of Drawings

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

[Figure 2] Rear perspective view of the brushless motor

[Fig.3] Exploded perspective view of the brushless motor

[Fig. 4] Perspective view of the back side for explaining the mounting state of the switching element to the heat radiating housing. [Fig. 5] Vertical sectional view of the brushless motor.

[Fig. 6 (a)] Perspective view showing cooling fan and bearing

[FIG. 6 (b)] A perspective view illustrating a state in which a bearing is attached to the cooling fan.

[Fig. 7] Cross-sectional view of the main part explaining the relationship between the cooling fan and the bearing FIG. 8 is a front perspective view illustrating another example of a brushless motor according to the present invention.

FIG. 9 is an exploded perspective view illustrating the configuration of a brushless motor according to a second exemplary embodiment.

FIG. 10 is an exploded perspective view illustrating a brushless motor according to a third exemplary embodiment.

FIG. 11 is a rear perspective view illustrating the configuration of the brushless motor according to the third exemplary embodiment.

[0011] 1 Heat dissipation housing

2 rotor

3 Stator

4 Inner cover

10 Switching element

16 Fixed part

22 Cooling fan

24 Housing recess (bulging part)

30 Bearing

32 coils

BEST MODE FOR CARRYING OUT THE INVENTION

[0012] Exemplary embodiments of the present invention will be described below with reference to the drawings.

[0013] <First exemplary embodiment>

FIG. 1 is a front perspective view showing an example of a brushless motor according to a first exemplary embodiment of the present invention. FIG. 2 is a rear perspective view of the brushless motor. Fig. 3 is an exploded perspective view of the brushless motor. This brushless motor includes a heat radiating housing 1, a rotor 2, a stator 3, and an inner cover 4. The rotor 2 and the stator 3 are accommodated in the heat dissipation housing 1 and the inner cover 4 is fixed to the heat dissipation housing 1 with screws, so that the heat dissipation housing 1, the rotor 2, the stator 3 and the inner cover 4 are integrated as a brushless motor. Composed.

The heat radiating housing 1 is formed in a bottomed cylindrical shape with a material having high thermal conductivity such as aluminum. As shown in FIG. 4, a switching element 10 such as an FET is screwed to the bottom outer surface la in a state of being laid down and in close contact. The heat of the switching element 10 is transferred to the heat dissipation housing 1. Conduct. The terminal 10a of the switching element 10 is bent at a right angle toward the rear. A terminal 10 a of the switching element 10 is inserted into a through hole 12 formed in the circuit board 11. The circuit board 11 is fixed to the heat radiating housing 1. If the terminal 10 a is soldered, the circuit board 11 on which the switching element 10 is arranged is fixed to the heat radiating housing 1.

Furthermore, a large number of vent holes 13 are formed on the bottom surface side of the peripheral surface lb of the heat radiating housing 1.

A plurality of engaging grooves 14 are formed on the peripheral surface on the opening side toward the bottom surface. Further, a connecting piece 15 having a screw hole is formed on the peripheral surface on the opening side so as to protrude.

[0016] The center of the inner surface lc of the bottom portion bulges to the front and is molded. A fixed portion 16 that fixes the bearing 30 of the mouth 2 by cutting is formed in the bulged portion (see FIG. 5).

A pinion gear 21 is provided at the tip of the rotating shaft 20 of the rotor 2. A cooling fan 22 is fixed to the rear end of the heat radiating housing 1 side. In the cooling fan 22, as shown in FIG. 6 (a), the center of the disk 23 bulges in an annular shape. Fins 25 are formed radially from the peripheral surface of the bulging portion 24. A large number of air holes 26 and 27 are formed in the disc 23 and the bulging portion 24.

The bulging portion 24 constitutes a housing portion for the bearing 30 that supports the rotating shaft of the rotor 2. As shown in FIGS. 6 (b) and 7, when the bearing 30 is attached to the rotary shaft 20 of the rotor 2, the bearing 30 is housed in the interior 24a of the bulging portion 24, and the cooling fan 22 and The bearings 30 are almost flush with each other, and the bearing 30 is almost within the thickness of the cooling fan 22.

[0019] When the bearing 30 is fixed to the fixed portion 16 of the heat radiating housing 1, the fixed portion 16 is accommodated in the bulging portion 24 together with the bearing 30 (see FIG. 5), and the cooling fan 22 and the heat radiating housing 1 The inner surface of the bottom portion is in a state of facing the nearest side lc, and the cooling effect by the cooling fan 22 can be maximized.

A plurality of cores 31 are formed on the stator 3 from the inner wall surface toward the inside. A winding wire (coil) 32 is wound around the core 31. Engaging protrusions 33 that engage with the engaging grooves 14 of the heat radiating housing 1 are formed on the outer wall surface, so that the heat radiating housing 1 securely holds the stator 3 during assembly.

[0021] The inner cover 4 has a ring gear 34 fixed inside. The rotation of the rotor is reduced by a planetary gear structure (not shown) and transmitted to the output shaft. In the case of this product, the rotation of the rotor is transmitted to the impact torque generation mechanism after deceleration, and the impact torque is generated and screw Tighten. If it is a drill driver, this impact torque generation mechanism is directly transmitted to the output shaft.

[0022] According to the brushless motor having the above configuration, the switching element 10 is fixed to the heat dissipation housing 1, the cooling fan 22 and the bearing 30 are attached to the rotor 2, and the housing unit in which the circuit board 11 is fixed to the heat dissipation housing 1. The rotor 2 and the stator 3 are accommodated. At this time, the bearing 30 of the rotor 2 is fitted into the fixed portion of the heat radiating housing 1, the engaging convex piece 33 of the stator 3 is engaged with the engaging groove 14 of the heat radiating housing 1, and the rotor is connected to the bearing portion of the inner cover 4. After fitting the front bearing 30 of 2, the assembly force S can be achieved by connecting the heat dissipation housing 1 and the inner cover 4 with screws. As a result, the brushless motor can be unitized, and when it is assembled in an apparatus such as an impact driver, it can be pre-assembled as a motor unit, so that the installation time in the apparatus can be shortened. In addition, the problem of the conventional brushless motor, which requires high manufacturing accuracy of the resin housing and stabilizes the performance when placed directly in the housing, can be avoided.

[0023] Also, the bearing 30 of the rotor 2 is supported by the heat radiating housing 1 and the inner cover 4, and the heat radiating housing 1 and the stator 3 are engaged by the engaging groove 14 and the engaging convex piece 33. Since the unit is unitized, the misalignment between the rotor 2 and the stator 3 rotating at high speed can be suppressed, and the generation of noise in the apparatus force can be suppressed.

[0024] Further, the switching element 10 that generates heat is laid down and fixed to the outside of the bottom surface of the heat radiating housing 1, and a cooling fan 22 is disposed close to the inside of the bottom surface to enhance the heat radiation effect. The overall length of the motor can be reduced, which can contribute to downsizing of the apparatus.

[0025] <Second exemplary embodiment>

In the brushless motor of the first exemplary embodiment, the force for connecting the heat radiating housing 1 and the inner cover 4 by using screws. In the second exemplary embodiment, as shown in FIG. Use the motor nut 40 to connect the heat radiating housing 1 and the inner cover 4 together. The motor nut 40 is formed in a ring shape and is formed by forming a thread 41 on the inner peripheral surface. A screw groove 42 is provided around the opening-side peripheral surface of the heat radiating housing 1, and the inner cover is provided. Positioning projection 43 is formed on No. 4 and the rotor 2 and stator 3 are accommodated in the heat radiating housing 1, and then the positioning projection 43 of the inner cover 4 is engaged with the engaging groove 14 of the heat radiating housing 1 so that the motor nut As shown in FIG. 9, the inner cover 4 and the heat radiating housing 1 can be connected by screwing 40 into the heat radiating housing 1. According to this motor, since the connecting piece for connecting the inner cover 4 and the heat radiating housing 1 does not need to be formed to protrude, there is no protrusion on the peripheral surface of the motor, and assembling to the device is improved. Power S can be.

In addition, in the case of the impact driver, the above-mentioned motor assembly is a force motor that realizes unitization of the motor and simplifies the assembly process in the line. This will be explained based on FIG. In this case, heat dissipation housing 1, stator 3, and inner cover 4 are integrally connected to impact driver assembly 50 with two screws 51, 51. Heat dissipation housing 1, stator 3, inner cover 4 is formed with connecting pieces 52, 53, 54 each having a through hole for inserting the screw 51, and the connecting piece 55 of the impact driver assembly 50 is formed with a screw hole to which the screw 51 is screwed. The pieces 53 and 54 are combined while being engaged with the engaging groove 14 of the heat radiating housing 1, and the screw 51 inserted from the through hole of the engaging piece 52 passes through the connecting pieces 52, 53 and 54, and the By screwing into a screw hole formed in the connecting piece 55 of the assembly 50, the motor can be assembled integrally with the impact driver assembly 50 as shown in FIG.

[0027] According to the assembly of the motor described above, the entire drive system inside the product (for example, impact driver) can be assembled, and the assembly process can be further simplified.

[0028] Although the invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention. is there.

[0029] This application is based on a Japanese patent application filed on June 9, 2006 (Japanese Patent Application No. 2006-161261), the contents of which are incorporated herein by reference. Industrial applicability

INDUSTRIAL APPLICABILITY The present invention can be used for a brushless motor, more specifically, a brushless motor provided with a cooling fan that cools heat generated from a switching element.

Claims

The scope of the claims

[1] a bottomed cylindrical heat radiating housing;

A rotor housed inside the heat dissipation housing;

A stator housed inside the heat dissipation housing;

A switching element that is closely fixed to the outer surface of the bottom of the heat-dissipating housing, and that turns on and off the energization of the stator coil;

A fixing portion provided on an inner surface of a bottom portion of the heat dissipation housing and fixing the bearing of the rotor;

A cooling fan fixed to the end of the rotor rotating shaft on the side of the heat dissipating housing and cooling the heat dissipating housing;

A brushless motor comprising: a housing recess formed in the center of the cooling fan and housing the bearing.

[2] Furthermore, a plurality of engagement grooves formed on the peripheral surface of the heat dissipation housing from the opening side to the bottom side of the heat dissipation housing;

The brushless motor according to claim 1, further comprising: an engaging convex piece formed on an outer peripheral surface of the stator and engaged with the engaging groove.

[3] The heat radiating housing is formed of a metal having excellent heat conduction,

The fixed part of the bearing is formed by cutting.

The brushless motor according to claim 2.