JP3704874B2 - Electric tool - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a power tool, particularly a hand-held power tool such as a power drill or a power screwdriver.
[0002]
[Prior art]
As shown in FIG. 6, the hand-held power tool generally includes a motor 2 at the rear end of the cylindrical housing 1 and a speed reducer 3 for reducing the output of the motor 2 at the front end. Further, the grip 4 having the switch handle 50 and the switch 5 that is opened and closed by the operation of the switch handle 50 is connected. In the figure, reference numeral 7 denotes a mounting plate for connecting the motor 2 and the speed reducer 3.
[0003]
In this case, the grip 4 is connected to the middle of the cylindrical housing 1 in terms of weight balance. Further, as shown in FIG. 7, the connection terminal 20 in the motor 2 is provided not on the front end side from which the output shaft 21 protrudes but on the rear end side.
Further, in a device capable of controlling the rotational speed of the motor 2, a heat radiating plate 60 to which a switching element 6 for driving a motor such as an FET is fixed is housed behind the motor 2 at the rear end of the housing 1. Yes.
[0004]
[Problems to be solved by the invention]
In the structure described above, the switch 5 in the grip 4 and the connection terminal 20 of the motor 2 are connected by drawing a long lead wire 51, and the wiring resistance is large, resulting in heat generation, lower output of the motor 2, and ease of assembly. It has the problem of being bad.
Also, the lead wire 52 for connecting the switch 5 and the switching element 6 must be long in the same manner as the lead wire 51, and must be accommodated in a narrow space between the motor 2 and the housing 1. Is bad.
[0005]
Further, the cooling air vent 23 is provided on the rear end surface and the rear outer peripheral surface of the motor 2, but the heat radiating plate 60 of the switching element 6 has a flow of the cooling air W passing through the air vent 23. It is a hindrance.
The mounting plate 7 has the motor 2 attached to one side and the speed reducer 3 attached to the other side. This assembly takes time.
[0006]
The present invention has been made in view of the above points, and the object of the present invention is to shorten and simplify the routing of the internal wiring, and to improve the output and assemblability. An object of the present invention is to provide an electric tool capable of further improving the assembling property by reducing the number of points, improving the cooling efficiency, and further improving the centering property between the motor and the speed reducer. .
[0007]
[Means for Solving the Problems]
Thus, the present invention incorporates a motor at the rear end of the cylindrical housing and a reduction gear for reducing the motor output at the front end and a switching element for driving the motor , and a switch is arranged in the middle of the cylindrical housing. the electric power tool connecting the grip is, the motor is provided with a connection pin output shaft connected to a reduction gear which is connected by a commutator and brushes as well as the lead frame to the switch at the front end projecting, motor A bracket provided with a cooling vent is formed by a good heat conductor, the switching element is attached to the bracket, and the bracket is integrally provided with a reduction plate coupling mounting plate. It has the feature in being. The distance between the switch on the grip and the connection terminal of the motor can be shortened , and connection is made with a lead frame without drawing a long lead wire. Reduction and output improvement can also be obtained .
[0008]
And since the switching element for driving the motor is also disposed in the vicinity of the front end of the motor, also it is possible to shorten the distance between the switch and the switching element arranged in the grip, also closes the front end face of the motor The bracket is formed of a good thermal conductor and the switching element for driving the motor is attached to the bracket. The bracket also serves as the heat dissipation plate for the switching element, so there is no need for an independent heat dissipation plate. can be reduced, because they provide a cooling vents in the bracket, it is possible to obtain an improvement in the cooling efficiency of the motor, in order to further is provided integrally mounting plate for the reduction gear connected to the bracket In addition , a separate mounting plate is not required.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
An example of an embodiment of the present invention will be described. FIGS. 1 to 3 show a motor 2 used in an electric power tool according to the present invention, and a bottomed cylindrical casing 25 having a closed rear end and the casing. A magnet 29 is fixed and a rotor 28 fixed to the output shaft 21 is supported and disposed in a motor housing including a bracket 26 that closes the front end opening 25. In the figure, reference numeral 24 denotes a crimping piece provided on the casing 25 to fix the bracket 26.
[0010]
The output shaft 21 projects outward from the front end on the bracket 26 side. A commutator 35 and a brush 36 are disposed inside the front end side, and the brush 36 is disposed on the front end side. Connected connection terminals 20 are provided. Further, cooling vents 23 are provided on both the front and rear end faces and the outer peripheral face on the front end side, an exhaust centrifugal fan 28 is provided on the front end side of the rotor 28, and an intake axial flow fan 27 is provided on the rear end side. ing.
[0011]
If the motor 2 is used in place of the motor in the electric tool shown in FIG. 6, the connection terminal 20 is positioned almost immediately above the switch 5 disposed in the grip 4, and for this reason, the motor 2 and the switch 5 can be connected in the shortest distance, and a connection using a lead frame instead of a lead wire is also possible.
4 and 5 show an example in which the bracket 26 of the motor 2 is formed of a good thermal conductor such as aluminum so as to have the function of the heat radiating plate 60, and the switching element 6 is attached to the outer surface of the bracket 26. FIG. The connection between the switch 5 and the switching element 6 can also be made at the shortest distance. Further, the air vent 23 is also formed in the bracket 26 so that the cooling air W of the motor 2 can be passed though the heat radiating plate 60 is also used.
[0012]
Further, a ring-shaped mounting plate 17 is integrally formed on the bracket 26 in the illustrated example via a connecting portion 18 having an arc-shaped cross section so that the speed reducer 3 can be directly fixed to the motor 2.
[0013]
【The invention's effect】
As described above, in the present invention, the motor incorporated in the rear end portion of the cylindrical housing is connected to the commutator, the brush, and the switch on the front end side from which the output shaft connected to the speed reducer projects. Therefore, it is possible to shorten the distance between the switch arranged on the grip connected to the middle of the cylindrical housing and the connection terminal of the motor, and it is necessary to route a long lead wire. Therefore, assemblability is improved and heat generation can be reduced and output can be improved.
[0014]
Assembly And in order to be switching elements are disposed in the vicinity of the front end of the motor, also because the distance between the switch and the switching element arranged in the grip can be shortened, leading to long leads are not required In addition to improving the performance, it is not necessary to secure a wiring space for the lead wire between the housing and the motor, so that the housing diameter can be reduced.
[0015]
The mounting of the switching element for driving the motor to the bracket bracket closing the end face of the motor is formed by thermal conductor, since the bracket is double as the heat radiation plate for the switching element, independent Since a heat radiating plate is not required, the number of parts can be reduced and the assemblability can be improved. At the same time, the bracket also contributes to the heat radiation of the motor.
[0016]
Furthermore, because it is provided with a cooling vent to the bracket, that the presence of the heat radiating member of the switching elements that never becomes an obstacle to the cooling air flow of the motor, of course, the passage of cooling air also becomes possible to improve the heat dissipation effect of the switching element, also because they provided integrally mounting plate for the reduction gear connected to the bracket, also the attachment plate for connection with a reduction gear without separately readily The motor and the speed reducer can be directly connected, so that the assemblability can be improved by reducing the number of parts, and the centering property between the motor and the speed reducer can be improved.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a motor in an example of an embodiment of the present invention.
FIG. 2 is a front view of the motor.
FIG. 3 is a rear view of the motor.
FIG. 4 is a broken and exploded perspective view of another example.
FIG. 5 is a longitudinal sectional view of the same.
FIG. 6 is a partial longitudinal sectional view of a conventional example.
FIG. 7 is an exploded perspective view of the above.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Housing 2 Motor 3 Reducer 4 Grip 5 Switch 6 Switching element 20 Connection terminal 21 Output shaft 26 Bracket 35 Commutator 36 Brush

Claims (1)

A motor is built in the rear end of the cylindrical housing, and a speed reducer that reduces the motor output and a switching element for driving the motor are built in the front end, and a grip with a switch arranged in the middle of the cylindrical housing is connected. An electric power tool, wherein the motor includes a commutator, a brush, and a connection terminal connected to the switch by a lead frame on a front end side from which an output shaft connected to a speed reducer projects, and closes the front end surface of the motor. And a bracket provided with a cooling vent is formed of a good thermal conductor, the switching element is attached to the bracket, and the bracket is integrally provided with a reduction plate connecting plate. Electric tool to do.

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