JPH02119547A - Noise field generation preventive device in power tool having double insulation structure - Google Patents

Abstract

PURPOSE:To miniaturize the title noise field generation preventive device, and to obviate the generation of noise field by installing one surface face of a plate- shaped insulator to the stator core of a commutator motor and connecting the other surface of the insulator to the metallic section of a power tool through another electrode. CONSTITUTION:A space section having a comparatively large sectional area for forming a cooling air path 3 is shaped between the main body case 2 of the power tool combining the case of a communication motor 4 and the stator core 5 of the commutator motor 4. Consequently, the formation of a capacity connector 17 for preventing the generation of noise field and the wiring of one electrode 16 can be conducted only by mounting an insulator 18 forming the capacity connector 17 for preventing the generation of noise field and the other electrode 21 at the positions of the outer circumference of the stator core 5 combining one electrode 16. Accordingly, the power tool can be miniaturized while wirings are connected easily, and the generation of noise field from a hedge trimmer 1 can be obviated effectively under a state in which the productivity of the power tool is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a power tool driven by a commutator motor, in particular of double insulated construction, the housing of which is at least partially made of metal. This invention relates to the structure of a noise radio wave generation prevention device.

(Prior Art) Conventionally, in electric tools in which a tool such as a cutter is driven by the rotation of a commutator or an electric motor, electro-sound radio waves are generated mainly from the spark generation part between the commutator and the brush, and this noise radio wave is It acts as an interference radio wave on surrounding electrical equipment, especially wireless equipment such as televisions and radio shades, and interferes with the reception of these wireless equipment.

As a preventive measure, generally the commutator motor is made of Ti.
Connect a check coil and a capacitor to the power supply circuit, or connect the capacitance between the armature of the commutator motor and the armature shaft between metal parts such as the stator core and the bearing case that holds the bearing of the electric machine's f-axis. Methods of mainly preventing the generation of asymmetrical voltage noise radio waves are known.

(Problem to be solved by the invention) However, in the former case, a special space is required to connect the choke coil, which is one of the reasons for preventing the miniaturization of power tools, and also requires a lot of effort to connect the wires. This has the disadvantage of reducing the productivity of the power tool accordingly. In addition, in the latter case, the stator core and m1
When connected with a conductor to a metal part such as the bearing case of ll-@, the human body comes into contact with Li2.The bearing case with it is only functionally insulated from the stator core, but not protectively insulated, so it passes electrical standards. could not.

Moreover, the same result was obtained even if the connection was made through a capacitor.

(Means for Solving the Problems) The present invention provides an electric tool that drives a tool by rotation of a commutator motor. ! ! One side of a plate-shaped insulator for preventing the generation of noise radio waves is attached to the stator core of the Ryuko electric coil as one electrode, and the insulator is attached to the other side of the insulator. Take the other electrode of approximately the same area as (J), and further connect the other electrode to the metal part of the electric fJ+ tool that is electrically connected to the electric fi-axis of the commutator motor. To the tool [
It is located in the noise radio wave generation prevention device.

(Function) In the case of the noise radio wave generation prevention device for a power tool with a double insulation structure configured in this way, there is a gap between the power tool case which also serves as the case of the commutator motor and the stator core of the commutator motor. There is a space with a relatively large cross-sectional area to form a cooling air passage, and the stator core exposed to the cooling air passage, in this case, 941 sound radio waves are placed on the outer circumference of the stator core that also serves as one electrode. In order to prevent this, one side of the plate-shaped insulator is attached, and the other side of the insulator is connected to the metal part of the power tool that is electrically connected to the armature shaft of the commutator motor via the other electrode. Thus, the stator core and armature shaft of the commutator motor can be easily connected capacitively.

(Effects of the Invention) As a result, the present invention makes it possible to attach a noise radio wave generation prevention device to the rectifier pre-current 1lJ131 for a power tool without requiring special space and with some wiring work omitted. This enables the miniaturization of power tools, facilitates wiring connections, and eliminates asymmetric voltage N.
It is also possible to effectively prevent the generation of acoustic waves.

(Embodiment) Next, the configuration of an embodiment of the present invention will be explained with reference to the drawings.

An electric T shell, for example, a well-known hedge trimmer 1 used for pruning trees or trimming fresh jf1, has a synthetic resin body case 2 in which a cooling air passage 3 is formed. In addition to the stator core 5 being removed, the armature shaft 7 of the armature 6 is rotatably supported via a bearing 8.9, and the pinion gear formed on the armature shaft 7 of the armature 6 is 180 attached to gear 11 for reduction gear meshing with 10
Eccentric cams (not shown) having different degrees and phases rotate, and the movable blades 14, 15 between the metal guide plates 12, 13 are mounted so as to be able to reciprocate over a fixed linear distance.

In the hedge trimmer 1 formed in this way, the stator core 5 of the commutator motor 814 is provided with a capacitive connection body for preventing the generation of noise radio waves, using the stator core 5 as one electrode 16 in the portion exposed to the cooling air passage 3. 17, in this case, one side of the insulator 18 made of Bakelite or ceramic or the like with a frame 19 formed on the outer periphery is attached via an adhesive, and the insulator In the recess 20 in one of the frame parts 18, the other electrode 21 forming the receiving contact body 17 on the other side of the insulator 18, in this case, the recess 2
The other electrode 21 with a size corresponding to the area of 0 is attached via adhesive, and a lead terminal 22 for external wiring is connected to the other 1 fl 121 through the end J-Oki passing hole 3. The insulating material cover 24 is recessed 2 while protruding to the outside.
0 and is attached via adhesive to form a noise/radio wave generation prevention enclosure suspension connection body 17, and the external wiring lead terminal 22 is connected to a power line or armature corresponding to the noise/radio wave generation prevention circuit. Bearing supporting armature 6@7 8.
9, etc., in this case, conduction is established to the bearing 8 that supports the armature shaft 7 of the quadrature armature 6 through the metal plate 22' (see Utility Model Application No. 60-6116 previously filed by the applicant). The capacitive connection body 1 for preventing the generation of noise radio waves is connected to the support @25 that rotatably supports the reduction gear 11 so as to
7, thereby creating a rectifier ' as shown in FIG.
T-den i! The stator core 5 of ll1a4 is capacitively coupled to the armature 7 of the armature 6 through a capacitive connector 17 for preventing the generation of noise radio waves, and the generation of noise radio waves mainly due to asymmetrical voltages is prevented.

Next, the operation of this embodiment will be explained.

In the case of the capacitive capacitor connection body 17 for preventing the generation of noise radio waves in the hedge trimmer 1 of the power tool configured as described above, the main body case 2 of the power tool which also serves as the case of the commutator motor 4 and the stator core 5 of the commutator motor 4 are used. There is a space with a relatively large cross-sectional area for forming a cold 1Jl air passage 3 between the stator core 5 exposed in this cooling air passage 3, which in this case also serves as one electrode 16. The formation of the capacitive connector 17 and the wiring of one electrode 16 can be completed by simply pasting the insulator 18 forming the capacitive connector 17 for preventing noise radio wave generation on the outer periphery of the stator core 5 and the other electrode 21 with adhesive. As a result, in this case, the capacitive connection body 17 for preventing the generation of noise radio waves can be connected to the commutator motor 4 of the power tool without requiring any special space, but with some wiring work omitted. This allows for the formation of mounting numbers and wiring, which makes it possible to reduce the size of the electric shell, facilitate wiring connections, and improve the productivity of the power tool. The generation of radio noise can be effectively prevented.

In addition, as shown in FIGS. 5 and 6, the capacitive connection body 17 for preventing noise radio wave generation of this embodiment has an insulating structure between the stator core 5 of the upper electrode 16 on one side and the electrode 21 on the other side. In addition to sandwiching the body 18, there is an insulation between the second one electrode 28 connected to the stator core 5 through the lead terminal 27 protruding from the end f insertion hole 26 and the other 11f pole 21. Two capacitive connecting bodies 30 for preventing the generation of noise radio waves can be connected with the body 29 in between, or two or more capacitive connecting bodies 30 can be connected in parallel for preventing the generation of noise radio waves. In addition to the shape shown in the drawings, the shape of the capacitor connector for preventing noise radio wave generation attached to the stator core 5 is as follows: Can be set arbitrarily.

[Brief explanation of the drawing]

FIG. 1 is a cutaway side view of an embodiment of the present invention, FIG. 2 is an enlarged cutaway side view of four parts thereof, FIG. 3 is a perspective view thereof, FIG. FIG. 6 is a cutaway side view and a perspective view of another embodiment of the case 30 for preventing radio wave generation. 1...Hedge trimmer 4...Commutator motor 5.
・Stator core 16 ・One electrode 17 ・
... IΔ radio wave generation prevention dosage connector 18 ... insulator
21... Electrode for use 22... Lead end f Applicant: Makita Denn Mfg. Co., Ltd. Agent Patent attorney: Oka 1'B Hidehiko (3 others)] 7 Figure 4 s5

Claims (1)

[Claims] In an electric tool that drives a tool by rotation of a commutator motor, one surface of a plate-shaped insulator is provided on a stator core of the commutator motor, and the stator core is used as one electrode to prevent generation of noise radio waves. and a second electrode having an area substantially equal to that of the insulator is attached to the other surface of the insulator, and the other electrode is electrically connected to the armature shaft of the commutator motor. A noise radio wave generation prevention device for a power tool with a double insulation structure, which is connected to a metal part.