JP2008200792A - Power tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power tool which ensures high strength by covering the entire body with a metallic housing, and forms small and compact body by shortening a periphery distance necessary for electrical insulation. <P>SOLUTION: A portable circular saw (power tool) is formed of a resin housing 3 in which a motor 2 is housed, the metallic housing 4 covering the resin housing 3, a carbon brush 24 for feeding power to the motor 2, and a metallic brush holder 26 for movably holding the carbon brush 24. Herein the brush holder 26 is inserted into a hole 4b formed in the metallic housing 4 and detachably held in a hole 3a formed in the resin housing 3. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electric tool in which a resin housing that houses a motor is covered with a metal housing.

  Conventionally, since the housing that covers the motor of the electric tool is generally made of resin, there has been a problem that if the housing is struck against other objects during operation or transportation, the housing is easily damaged. For this reason, the structure which covers a resin-made housing with a metal housing is proposed.

  In power tools, power is supplied to the motor via a carbon brush that is in sliding contact with the armature of the rotor. The carbon brush is worn by sliding contact with the armature, so it can be easily replaced. For this purpose, a configuration is adopted in which the carbon brush is detachably held with respect to the housing.

  Here, the structure of the power feeding part of the conventional electric power tool will be described with reference to FIGS. 9 and 10.

  9 is a cross-sectional view of a power feeding portion of a conventional power tool, FIG. 10 is a cross-sectional view taken along the line DD of FIG. 9, and the illustrated power tool houses a motor 102 in a resin housing 103. The housing 103 is covered with a metal housing 104.

  A carbon brush 124 is in contact with the outer periphery of the armature 123 of the motor 102 by a spring 125, and the carbon brush 124 is radiated in a radial direction (vertical direction in FIGS. 9 and 10) by a metal brush holder 126. Is slidably held on the surface. Here, a power supply wire 127 is connected to the outer periphery of the brush holder 126, and the outer periphery of the brush holder 126 is covered with a resin sleeve 128, and both are integrated to form one part. Although not shown, the armature 123 has carbon brushes 124 in contact with two locations facing the outer periphery thereof.

  A cap 129 is screwed to the inner periphery of the outer end portion of the resin sleeve 128, and the spring 125 is compressed between the cap 129 and the carbon brush 124. It is urged inward and pressed against the outer periphery of the armature 123 with a predetermined pressure.

  By the way, holes 103 a and 104 b are respectively formed in the resin housing 103 and the metal housing 104, and the carbon brush 124, the brush holder 126, and the resin sleeve 128 that are assembled and integrated in advance are connected to the resin housing 103. The holes 103 a and 104 b of the metal housing 104 are inserted into the housings 103 and 104, and these are detachably held when the resin sleeve 128 is fitted into the hole 104 b of the metal housing 104. Then, by tightening a screw 130 screwed into the metal housing 104 and pressing it on the outer periphery of the resin sleeve 128, the assembled carbon brush 124, the brush holder 126, and the resin sleeve 128 are made into the metal housing. 104 is fixed.

  However, in the conventional power tool feeding structure shown in FIG. 9 and FIG. 10, a configuration in which the integrated brush holder 126 and the resin sleeve 128 are held in the metal housing 104 is employed. The brush holder 126 and the metal housing 104 are close to each other, and the edge distance necessary for electrical insulation between the brush holder 126 and the metal housing 104 is increased, and it is necessary to secure a relatively large insulating space S shown in FIG. . For this reason, there has been a problem that the metal housing 104 and, consequently, the entire power tool is increased in size.

  The present invention has been made in view of the above problems, and the object of the invention is to reduce the edge distance necessary for electrical insulation while covering the whole with a metal housing to ensure high strength, and to be compact and compact. An object of the present invention is to provide an electric tool that can be made simple.

  In order to achieve the above object, the invention described in claim 1 is a resin housing that houses a motor, a metal housing that covers the resin housing, a carbon brush for supplying power to the motor, and a movable motor. In the electric tool including the metal brush holder to hold, the brush holder is detachably held in the hole formed in the resin housing through the hole formed in the metal housing. .

  According to a second aspect of the present invention, in the first aspect of the invention, the outer periphery of the brush holder is covered with a resin sleeve, the two are integrated into one component, and a cap is screwed onto the resin sleeve. It is characterized by.

  According to a third aspect of the present invention, the electric power tool according to the first or second aspect is provided with a disk-shaped saw blade that is rotationally driven by the motor, and a fulcrum portion that is integrally formed with the metal housing. The metal housing is moved up and down together with the resin housing, the motor, and the saw blade to adjust the cutting depth.

  According to the first aspect of the present invention, since the conductive brush holder is held in the hole formed in the non-conductive resin housing, the distance between the brush holder and the metal housing is larger than the conventional one, and the electrical The edge surface distance required for mechanical insulation is short, and as a result, the size of both housings, and thus the entire power tool, can be reduced. Further, since the resin housing is covered with a metal housing having a strength higher than that of the resin, the strength of the electric tool can be increased.

  According to the second aspect of the present invention, the outer periphery of the brush holder is covered with the resin sleeve so that both are formed as one part, and the cap is screwed onto the resin sleeve, so that the cap holder is integrated without being removed. The brush holder, the resin sleeve, and the carbon brush can be integrally attached and detached as a unit, and the carbon brush can be easily replaced with good workability.

  Since the fulcrum part used as the rotation center of an electric tool was integrally formed in the metal housing according to the invention of Claim 3, the intensity | strength of a fulcrum part is raised.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

<Embodiment 1>
1 is a side view of a portable circular saw as an embodiment of the electric tool according to the present invention, FIG. 2 is a broken sectional view taken along line AA in FIG. 1, and FIG. 3 is a sectional view taken along line BB in FIG. 4 is a cross-sectional view taken along the line CC of FIG. 3, FIG. 5 is a perspective view of a resin housing, and FIG. 6 is a perspective view of a metal housing.

  As shown in FIG. 2, the portable circular saw 1 according to the present embodiment includes a resin housing 3 that houses a motor 2 that is a drive source, and a metal housing 4 that covers the resin housing 3. A handle 5 is attached to the metal housing 4.

  The rotor 6 of the motor 2 is rotatably supported at both ends in the axial direction by bearings 7 and 8, and a pinion 9 is integrally formed at the front end in the axial direction (the left side in FIG. 2 is the front). ing. A cooling fan 10 is bound to a portion of the rotor 6 at the rear of the bearing 7.

  Further, below the rotor 6, a drive shaft 11 is arranged in parallel with the rotor 6 so as to be rotatably supported by bearings 12 and 13 at both ends in the axial direction. A gear 14 that meshes with the pinion 9 is attached. A disc-shaped saw blade 15 is detachably attached to the front end portion of the drive shaft 11 with a bolt 16, and a substantially upper half portion of the outer periphery of the saw blade 15 is covered with a saw cover 17. Further, the outer peripheral portion of the substantially semicircular portion other than the portion covered by the saw cover 17 of the saw blade 15 is covered with a protective cover 18 that is concentric with the saw blade 15 and is held rotatably. The protective cover 18 is urged in a direction to cover the outer periphery of the saw blade 15 by a return spring 19 and rotates against the urging force of the return spring 19 by swinging of the saw blade 15 in a cutting operation. The saw blade 15 is exposed.

  Incidentally, the resin housing 3, the metal housing 4, the motor 2, the saw blade 15, and the like described above are supported by the base 20 so as to be rotatable up and down around the pin 21 shown in FIG. 1. Here, as shown in FIG. 6, an arm 4A is integrally formed on the front end side portion of the metal housing 4, and a boss portion 4a, which is a fulcrum portion, is integrally formed at the tip of the arm 4A. ing.

  On the other hand, as shown in FIG. 1, a bracket 21 is erected on one end of the base 20, and the bracket 21 is inserted into the boss 4 a of the arm 4 </ b> A formed on the metal housing 4. As described above, the resin housing 3, the metal housing 4, the motor 2, the saw blade 15, and the like are supported by the pins 21 so as to be vertically rotatable with respect to the base 20.

  Here, the power feeding structure to the motor 2 will be described with reference to FIGS.

  Electric power is supplied to the motor 2 through carbon brushes 24 (only one of them is shown in FIGS. 3 and 4) that is slidably contacted with two opposite positions on the outer periphery of the armature 23 of the rotor 6. 23, the carbon brush 24 is detachably held with respect to the resin housing 3 and the metal housing 4 so that it can be easily replaced. Therefore, as shown in FIGS. 5 and 6, circular holes 3 a and 4 b (only one in FIGS. 5 and 6) are formed on opposite sides of the rear ends of the resin housing 3 and the metal housing 4. Are respectively formed. As shown in FIGS. 3 and 4, the inner diameter of the circular hole 4 b formed in the metal housing 4 is set larger than the inner diameter of the circular hole 3 a formed in the resin housing 3.

  As shown in FIGS. 3 and 4, carbon brushes 24 are brought into contact with two opposing portions of the outer periphery of the armature 23 by springs 25, and the carbon brushes 24 are radially arranged by a metal brush holder 26. It is held so as to be slidable (in the vertical direction in FIGS. 3 and 4). Here, a power supply wire 27 is connected to the outer periphery of the brush holder 26, and the outer periphery of the brush holder 26 is covered with a resin sleeve 28, and both are integrated to form one part.

  A cap 29 is screwed on the inner periphery of the outer end of the resin sleeve 28, and the spring 25 is compressed between the cap 29 and the carbon brush 24. The spring 25 causes the carbon brush 24 to move in the radial direction. The armature 23 is biased inward and pressed against the outer periphery of the armature 23 with a predetermined pressure.

  Incidentally, as described above, the resin housing 3 and the metal housing 4 are respectively formed with the circular holes 3a and 4b (see FIGS. 5 and 6), and the carbon brush 24 and the brush holder that are assembled and integrated in advance. 26 and the resin sleeve 28 are inserted into the housings 3 and 4 through the circular holes 3 a and 4 b of the resin housing 3 and the metal housing 4, and the resin sleeve 28 is inserted into the circular holes 3 a of the resin housing 3. It is detachably held by being fitted. When the carbon brush 24, the brush holder 26, and the resin sleeve 28 are held by the resin housing 3 in this way, the screws 30 that are screwed into the resin housing 3 are inserted from the holes 3 b formed in the resin housing 3. When tightened with a tool (not shown) such as a screwdriver, the assembled and integrated carbon brush 24, brush holder 26, and resin sleeve 28 are fixed to the resin housing 3, and the removal of these is reliably prevented. . In the assembled state, the cap 29 is accommodated in the metal housing 4 so that the cap 29 does not protrude from the outer surface of the metal housing 4.

  Thus, in the portable circular saw 1 configured as described above, when a switch (not shown) is turned on to supply power to the motor 2, the motor 2 is started, and the rotation of the rotor 6 meshes with each other. The pinion 9 and the gear 14 are decelerated and transmitted to the drive shaft 11, and the drive shaft 11 and the saw blade 15 mounted on the drive shaft 11 are rotationally driven at a predetermined speed. Disconnected. The cutting depth at this time is determined by holding the handle 5 and moving the resin housing 3, the metal housing 4, the motor 2, the saw blade 15, etc. up and down integrally with the base 20 around the pin 21. Adjusted by.

  As described above, in the present embodiment, the conductive brush holder 26 is held in the circular hole 3a formed in the non-conductive resin housing 3, so that the distance between the brush holder 26 and the metal housing 4 is larger than the conventional distance. As a result, the distance between the edges required for electrical insulation between the two housings can be shortened. As a result, the housings 3 and 4 and thus the portable circular saw 1 as a whole can be reduced in size and size. If the housings 3 and 4 are reduced in size and size in this way, the range in which the housings 3 and 4 and the saw blade 15 can be rotated up and down increases, and as a result, the adjustment allowance for the cutting depth also increases. An effect is obtained. As shown in FIG. 7, if the lengths of the brush holder 26 and the resin sleeve 28 are shortened, the resin housing 3 and the metal housing 4 can be further reduced in size and size.

  In the portable circular saw 1 according to the present embodiment, since the resin housing 3 is covered with the metal housing 4 having a higher strength than the resin, the strength of the portable circular saw 1 is increased, Even if the portable circular saw 1 hits another object during transportation, problems such as easy damage will not occur.

  Further, in the present embodiment, the outer periphery of the brush holder 26 is covered with the resin sleeve 28 to form both parts as one part, and the cap 29 is screwed to the resin sleeve 28, so that the cap 29 is integrated without being removed. The formed brush holder 26, the resin sleeve 28, and the carbon brush 24 can be integrally attached and detached as a unit, and the carbon brush 24 can be easily replaced with good workability.

  Further, in the present embodiment, the boss portion 4 a serving as a fulcrum portion for inserting and supporting the pin 21 serving as the rotation center of the resin housing 3, the metal housing 4, the motor 2, the saw blade 15, etc. is provided on the metal housing 4. Since it is formed integrally with the arm 4A (see FIG. 6), the strength of the fulcrum is increased.

<Embodiment 2>
Next, a second embodiment of the present invention will be described with reference to FIG.

  FIG. 8 is a cross-sectional view of the power feeding part of the portable circular saw according to the second embodiment of the present invention. In this figure, the same elements as those shown in FIG. The re-explanation about them is omitted.

  The present embodiment is characterized in that the resin sleeve 28 in the above embodiment is omitted, and the brush holder 26 is directly fitted and held in the circular hole 3a of the resin housing 3, and the cap 29 is a resin housing. 3 is screwed into the circular hole 3a.

  Thus, in this embodiment, the same effect as in the above embodiment can be obtained, but the brush holder 26 is directly fitted and held in the circular hole 3a of the resin housing 3, so that the structure can be simplified. Can do. However, in the present embodiment, when the carbon brush 24 is replaced, it is necessary to remove the cap 29 and attach / detach the carbon brush 24 and the brush holder 26.

  Although the present invention has been described with respect to the embodiment in which the present invention is applied particularly to a portable circular saw, it is needless to say that the present invention can be similarly applied to any other power tool.

It is a side view of the portable circular saw which concerns on Embodiment 1 of this invention. FIG. 2 is a broken sectional view taken along line AA in FIG. 1. FIG. 3 is a sectional view taken along line B-B in FIG. 2. It is CC sectional view taken on the line of FIG. It is a perspective view of the resin-made housing of the portable circular saw which concerns on Embodiment 1 of this invention. It is a perspective view of the metal housing of the portable circular saw which concerns on Embodiment 1 of this invention. Sectional drawing which shows the modification of the electric power feeding part of the portable circular saw which concerns on Embodiment 1 of this invention (a figure similar to FIG. 4). It is sectional drawing of the electric power feeding part of the portable circular saw which concerns on Embodiment 2 of this invention. It is sectional drawing of the electric power feeding part of the conventional electric tool. FIG. 10 is a sectional view taken along line D-D in FIG. 9.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Portable circular saw 2 Motor 3 Resin housing 3a Round hole (hole) of resin housing
3b Resin housing hole 4 Metal housing 4A Metal housing arm 4a Metal housing boss 4b Metal housing circular hole (hole)
5 Handle 6 Rotor 7, 8 Bearing 9 Pinion 10 Cooling fan 11 Drive shaft 12, 13 Bearing 14 Gear 15 Saw blade 16 Bolt 17 Saw cover 18 Protective cover 19 Return spring 20 Base 21 Pin 22 Bracket 23 Armature 24 Carbon brush 25 Spring 26 Brush Holder 27 Feeding wire 28 Resin sleeve 29 Cap 30 Screw

Claims (3)

In a power tool including a resin housing that houses a motor, a metal housing that covers the resin housing, a carbon brush for supplying power to the motor, and a metal brush holder that holds the motor movably,
An electric tool characterized in that the brush holder is detachably held in a hole formed in the resin housing through a hole formed in the metal housing.   2. The electric tool according to claim 1, wherein an outer periphery of the brush holder is covered with a resin sleeve, and both are integrated to form one part, and a cap is screwed onto the resin sleeve. A disk-shaped saw blade that is driven to rotate by the motor, and the metal housing is moved up and down together with the resin housing, the motor, and the saw blade around a fulcrum formed integrally with the metal housing; The electric tool according to claim 1, wherein the depth of cut is adjustable.

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