JP2006167843A - Power tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power tool such as a hand-held grinder, effectively cooling a bearing of the power tool. <P>SOLUTION: In this power tool, a motor 5 for driving a tool part 2 is stored in a resin-made housing 1, and a bearing 8 supporting a motor shaft 6 is held in the housing 1 through a bearing holding part. The bearing holding part is fixed to the housing 1 as a heat transfer bearing holding member 3 separate from the resin-made housing 1, and part of the heat transfer bearing member 3 is exposed as a radiating part 3b from the surface of the housing 1. Heat generated in the bearing 8 can be radiated from the radiating part 3b of the heat transfer bearing holding member 3 to the outside of the housing 1 to properly cool the bearing 8. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a power tool such as a hand-held grinder.

  A power tool such as a hand-held grinder has a resin housing. A motor for driving the tool portion is housed in the housing, and a bearing for supporting the motor shaft is formed through a bearing holding portion integrally formed with the housing. It is hold | maintained in a housing (for example, refer patent document 1).

  If the motor is started and the motor shaft rotates at a high speed in the housing when working with a power tool, the bearing will generate heat and adversely affect the resin bearing holder. To prevent this, there is a gap between the bearing holder and the bearing. Attempts have been made to dissipate heat generated in the bearing from the bearing house and the heat dissipating part formed in the bearing house (for example, refer to Patent Document 2). .

JP 2002-154042 A Japanese Patent Laid-Open No. 9-285976

  However, in the conventional heat dissipation method, since the bearing house is housed in the housing, the heat dissipation is low and there is a possibility that the bearing holding portion and the like may still be adversely affected.

  Therefore, an object of the present invention is to provide a power tool such as a portable grinder that can solve the above-mentioned problems.

  In order to solve the above-mentioned problem, the invention according to claim 1 is directed to a bearing for supporting a motor shaft (6) in which a motor (5) for driving a tool portion (2) is housed in a resin housing (1). 8) In the electric tool in which the housing (1) is held via the bearing holding portion, the bearing holding portion is a heat transfer bearing holding member (3) separate from the resin housing (1). ) And a power tool in which a part of the heat conductive bearing holding member (3) is exposed from the surface of the housing (1) as a heat radiating portion (3b) is employed.

  Moreover, the invention according to claim 2 is the electric tool according to claim 1, wherein the air hole (19) through which the cooling air of the motor (5) passes is formed in the heat conductive bearing holding member (3). adopt.

  According to a third aspect of the present invention, in the electric tool according to the first or second aspect, the fin (3c) with which the cooling air of the motor (5) contacts is formed on the heat conductive bearing holding member (3). Adopt a power tool.

  According to a fourth aspect of the present invention, in the electric tool according to any one of the first to third aspects, the resin housing (1) is divided and the heat conductive bearing holding member (3) is entirely formed. An electric tool sandwiched between connecting portions of the housing (1) so as to be exposed on the surface of the housing (1) over the circumference is employed.

  Moreover, the invention which concerns on Claim 5 is an electric tool in any one of Claim 1 thru | or 4. WHEREIN: The thermal radiation part (3b) which is a part of heat conductive bearing holding member (3) is a housing (1). The electric tool exposed from the surface of the housing (1) at a location separated from the gripping part of the) is adopted.

  The invention according to claim 6 is the electric tool according to any one of claims 1 to 5, wherein the insulating cushion body (18) is provided between the heat-conductive bearing holding member (3) and the bearing (8). ) Is used.

  According to the first aspect of the present invention, the motor (5) for driving the tool portion (2) is housed in the resin housing (1), and the bearing (8) for supporting the motor shaft (6) is provided in the housing ( 1) In the electric tool held by the bearing holding portion, the bearing holding portion is fixed to the housing (1) as a heat conductive bearing holding member (3) separate from the resin housing (1), Since a part of this heat transfer bearing holding member (3) is an electric tool exposed from the surface of the housing (1) as a heat radiating part (3b), heat generated in the bearing (8) is transferred to the heat transfer bearing holding member. Heat can be radiated from the heat radiating portion (3b) of (3) to the outside of the housing (1), and the bearing (8) can be cooled appropriately.

  According to the second aspect of the present invention, in the electric tool according to the first aspect, the air hole (19) through which the cooling air of the motor (5) passes is formed in the heat conductive bearing holding member (3). Therefore, the flow of the cooling air of the motor (5) is improved to improve the cooling efficiency of the motor (5), and at the same time the heat generated in the bearing (8) is transferred to the heat transfer bearing holding member (by the cooling air of the motor (5)). The heat can be radiated more effectively from 3).

  According to the invention according to claim 3, in the electric tool according to claim 1 or claim 2, the fin (3c) with which the cooling air of the motor (5) contacts is formed in the heat conductive bearing holding member (3). Therefore, the heat generated in the bearing (8) can be radiated more effectively by applying the cooling air of the motor (5) to the fin (3c).

  According to the invention of claim 4, in the electric tool according to any one of claims 1 to 3, the resin housing (1) is divided and formed so that the heat transfer bearing holding member (3) Since the power tool is sandwiched between the connecting portions of the housing (1) so as to be exposed on the surface of the housing (1) over the circumference, the heat transfer bearing holding member (3) is firmly fixed to the housing (1). At the same time, since the area exposed to the outside of the housing (1) increases, the cooling effect of the bearing (8) is improved. In this case, the appearance of the electric power tool can be improved by forming the surface of the heat conductive bearing holding member (3) and the surface of the housing (1) on the same plane.

  According to the invention which concerns on Claim 5, in the electric tool in any one of Claim 1 thru | or 4, the heat radiating part (3b) which is a part of heat conductive bearing holding member (3) is a housing (1 ) Is a power tool that is exposed from the surface of the housing (1) at a location separated from the gripping portion, so that the hand holding the worker's housing (1) is the heat radiating portion (3b) of the heat transfer bearing holding member (3). ) Accordingly, it is possible to prevent the cooling effect from being lowered by the heat radiating portion (3b) of the heat conductive bearing holding member (3).

  According to the invention which concerns on Claim 6, in the electric tool in any one of Claims 1 thru | or 5, an insulating cushion body (18) is provided between a heat conductive bearing holding member (3) and a bearing (8). ) Is provided with an insulating cushion body (18), so that vibration, impact, etc. can be mitigated, and the gap between the heat conductive bearing holding member (3) and the motor (5) is properly adjusted. Can be insulated.

  The best mode for carrying out the invention will be described below with reference to the drawings.

  As shown in FIGS. 1A, 1B, and 1C, the portable grinder as the electric tool has a resin housing 1 formed in a substantially cylindrical shape so that an operator can hold it with one hand. In addition, it has a disk-shaped grindstone 2 which is a tool part for performing a grinding operation.

  The resin-made housing 1 is divided into front and rear, and the outer peripheral surface of a heat conductive bearing holding member 3 described later is exposed from the joint. The front housing 1a serving as a gripping part to be grasped by the operator's hand is formed into a substantially cylindrical shape by resin injection molding, and the rear housing 1b is formed by combining the upper and lower split pieces formed by resin injection molding. Is formed into a substantially cylindrical shape. A metal gear case 4 is connected to the front end of the front housing 1a serving as a grip portion, and the grindstone 2 is disposed below the gear case 4.

  As shown in FIGS. 2 and 3, a motor 5 for driving the grindstone 2 is accommodated in the front housing 1a. The motor 5 is arranged such that the motor shaft 6 is positioned on the axial center of the cylindrical front housing 1a. The front end portion 6a of the motor shaft 6 protrudes from the front housing 1a into the gear case 4 and is supported by a front bearing 7 fixed in the gear case 4, and the rear end portion 6b of the motor shaft 6 is a front housing. A rear bearing 8 supports the rear portion 1a. The motor shaft 6 is supported at both ends by front and rear bearings 7 and 8 and rotates at high speed.

  A cooling fan 9 is fixed to the front end 6a of the motor shaft 6 so as to be accommodated in the front housing 1a. The cooling fan 9 is fixed in the front housing 1a and is surrounded by a casing 10 having a hole 10a through which cooling air is passed at the center. As shown in FIGS. 2 and 3, a gap b is provided between the motor 5 and the inner wall surface of the front housing 1a, and an intake hole a is formed in the rear housing 1b connected to the rear end of the front housing 1a. An exhaust hole c is formed in the gear case 4 connected to the front end of the front housing 1a. When the cooling fan 9 rotates together with the motor shaft 6, outside air is taken into the rear housing 1b from the intake hole a, cools the motor 5 through the gap b of the front housing 1a, and then goes out of the machine through the exhaust hole c. Discharged.

  A commutator 11 is attached to the rear end 6 b of the motor shaft 6, and a brush 12 attached to the front housing 1 a is in contact with the commutator 11. The commutator 11 and the brush 12 are also cooled by the cooling fan 9 by the cooling air taken from the intake port a.

  As shown in FIG. 2, a small bevel gear 13 that is fixed to the front end 6 a of the motor shaft 6 and a large bevel gear 14 that meshes with the small bevel gear 13 are housed in the gear case 4. The large bevel gear 14 is fixed to a drive shaft 16 that is vertically supported by a gear case 4 via a bearing 15. The drive shaft 16 protrudes below the gear case 4, and the grindstone 2 is detachably fixed to the protruding portion. The Power is transmitted from the motor shaft 6 to the small bevel gear 13 and the large bevel gear 14 by the rotation of the motor 5, and the grindstone 2 rotates to grind the workpiece (not shown).

  As shown in FIG. 3, an on / off switch 15 and the like are accommodated in the rear housing 1b. When the operator switches the on / off switch 15, the motor 5 rotates or stops.

  When the motor shaft 6 of the motor 5 rotates, the front and rear bearings 7 and 8 generate heat, but the heat generated in the front bearing 7 is transmitted to the metal gear case 4 and radiated outside the machine. Further, the heat generated in the rear bearing 8 is radiated to the outside from the heat conductive bearing holding member 3 shown in FIGS. 4 (A), (B), (C), (D), and (E).

  This heat transfer bearing holding member 3 is provided to fulfill the role of a bearing holding portion that has been molded integrally with the housing and the role of cooling the rear bearing 8 in order to hold the rear bearing 8 in a resin housing. It is done. That is, as shown in FIGS. 2 and 3, the heat transfer bearing holding member 3 is fixed to the housing 1 as a separate member from the resin housing 1, and a part of the heat transfer bearing holding member 3 radiates heat. As a part, it is exposed from the surface of the housing 1.

  As shown in FIGS. 4 (A), (B), (C), (D), and (E), the heat transfer bearing holding member 3 extends radially between the inner ring 3a, the outer ring 3b, and the inner and outer rings 3a and 3b. And a plurality of arms 3c connecting the two, and the whole is integrally formed of a metal having a good thermal conductivity, such as an aluminum alloy. Incidentally, when the heat conductive bearing holding member 3 is made of, for example, an aluminum die casting alloy and the housing 1 is made of, for example, nylon resin or ABS resin, the thermal conductivity is 92 to 96 W / m · K for the aluminum die casting alloy, and the nylon resin. Or since it is 0.19-0.36 W / m * K in an ABS resin, this heat conductive bearing holding member 3 can acquire the big heat dissipation effect.

  The rear end of the inner ring 3a is closed by the end plate 17, and the rear bearing 8 is fitted into the recess of the inner ring 3a formed thereby as shown in FIGS. An insulating cushion body 18 is provided between the inner ring 3a and the rear bearing 8 as necessary. As described above, the insulating cushion body 18 is interposed between the heat conductive bearing holding member 3 and the rear bearing 8, so that vibration, impact, etc. applied to the motor 5, the bearing 8 and the like are alleviated, and the heat conductive bearing holding member. 3 and the motor 5 are electrically insulated.

  An air hole 19 that is a substantially fan-shaped through hole is formed between the plurality of arms 3c. The cooling air taken in from the intake port a by the cooling fan 9 passes through these air holes 19, and the arm 3 c functions as a cooling fin that enhances the cooling effect by the contact of the cooling air. It is also possible to increase the cooling effect by adding various fins to the arm 3c and other parts. In each arm 3c, a set screw insertion hole 20 is formed so as to cross the arm 3c, and as shown in FIG. 3, a set screw 21 passed through each insert hole 20 is screwed into the rear end of the front housing 1a. Thus, the heat conductive bearing holding member 3 is fixed to the housing 1.

  As described above, since the heat conductive bearing member 3 is located at a portion separated from the front housing 1a which is the grip portion of the housing 1, the hand of the operator holding the grip portion is exposed to the heat conductive bearing member 3. Therefore, the cooling effect is prevented from being reduced.

  As shown in FIGS. 1 to 3, the outer ring 3 b is sandwiched between the connecting portions of the front and rear housings 1 a and 1 b that are separately formed. Specifically, as shown in FIGS. 2 and 4C and 4E, a boss portion 22 projecting rearward from the rear end of the front housing 1a connects the air hole 19 of the heat conductive bearing holding member 3 to the rear housing. The fixing screw 23 inserted through the rear housing 1b from the rear end of the rear housing 1b is screwed into the boss portion 22 so that the front and rear housings 1a and 1b sandwich the heat conductive bearing holding member 3 therebetween. Connected and integrated. Further, the outer ring 3b is sandwiched between connecting portions of the front and rear housings 1a and 1b so as to be exposed on the surface of the housing 1 over the entire circumference of the housing 1 from the joints of the front and rear housings 1a and 1b. Thereby, the area exposed outside the housing 1 increases. Although it is possible to form irregularities to be cooling fins on the outer periphery of the outer ring 3b, in the case of this embodiment, the surface of the heat conductive bearing holding member 3 and the surface of the housing 1 are formed on the same surface. Is done.

  Next, the operation of the portable grinder configured as described above will be described.

  1 to 3, when the operator holds the front housing 1 a with one hand and turns on the on / off switch 15 with the finger of the other hand, the motor 5 rotates and the small bevel gear 13 is moved from the motor shaft 6. The power is transmitted to the large bevel gear 14 and the grindstone 2 rotates. Thereby, it can grind with respect to the workpiece | work which is not shown in figure.

  Simultaneously with the rotation of the motor shaft 6, the cooling fan 9 rotates, and outside air is taken into the rear housing 1b from the intake hole a of the rear housing 1b. The outside air cools the motor 5 from the rear housing 1b through the gap b between the inner wall surface of the front housing 1a and the motor 5, and then passes through the hole 10a of the casing 10 and from the exhaust hole c of the gear case 4. It is discharged outside the machine.

  The front and rear bearings 7 and 8 generate heat due to the rotation of the motor shaft 6, but the heat generated in the front bearing 7 is transmitted to the metal of the gear case 4 and radiated from the outer surface to the outside of the machine. 7 is cooled. Moreover, since a worker's hand does not cover the heat-conductive bearing member 3, the cooling effect is prevented from being lowered.

  The heat generated in the rear bearing 8 is transferred to the inner ring 3a, the end plate 17, the arm 3c, and the outer ring 3b of the heat conductive bearing holding member 3, and is radiated from the outer surface of the outer ring 3b to the outside of the machine. To be cooled. Further, when the cooling air from the cooling fan 9 passes through the air holes 19 of the heat transfer bearing holding member 3, the arm 3 c comes in contact with the arm 3 c and takes heat away. Increase.

  When the grinding operation is completed and the operator turns off the on / off switch 15, the motor 5 stops and the grindstone 2 stops rotating. When the motor 5 stops, the cooling fan 9 also stops, but after that, heat is released from the rear bearing 8 through the heat conductive bearing holding member 3 to the outside of the machine.

  Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments. For example, in the above embodiment, the portable grinder has been described as an example, but the present invention can also be applied to other power tools.

The portable grinder which concerns on this invention is shown, (A) is a top view, (B) is a front view, (C) is a bottom view. 2A is a cross-sectional view taken along the line II-II in FIG. FIG. 3B is a cross-sectional view taken along line III-III in FIG. The heat-conductive bearing holding member integrated in the portable grinder which concerns on this invention is shown, (A) is a perspective view, (B) is a front view, (C) is a right view, (D) is a figure (C), DD sectional view taken on line D, (E) is a left side view.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Housing 2 ... Grinding wheel 3 ... Heat-conducting bearing holding member 3b ... Outer ring 3c ... Arm 5 ... Motor 6 ... Motor shaft 8 ... Bearing 18 ... Insulating cushion body 19 ... Air hole

Claims (6)

  In a power tool in which a motor that drives a tool portion is housed in a resin housing, and a bearing that supports the motor shaft is held by the housing via a bearing holding portion, the bearing holding portion is separate from the resin housing. A power tool fixed to a housing as a heat transfer bearing holding member of a body, wherein a part of the heat transfer bearing holding member is exposed as a heat radiating portion from the surface of the housing.   2. The electric tool according to claim 1, wherein an air hole through which the cooling air of the motor passes is formed in the heat conductive bearing holding member.   3. The electric power tool according to claim 1, wherein fins that contact the cooling air of the motor are formed on the heat conductive bearing holding member.   The electric power tool according to any one of claims 1 to 3, wherein the resin housing is divided and formed so that the heat transfer bearing holding member is exposed on the surface of the housing over the entire circumference. An electric tool characterized by being sandwiched.   5. The electric power tool according to claim 1, wherein the heat dissipating part, which is a part of the heat conductive bearing holding member, is exposed from the surface of the housing at a location separated from the grip part of the housing. A featured electric tool.   6. The electric power tool according to claim 1, wherein an insulating cushion body is provided between the heat conductive bearing holding member and the bearing.

Images