JP2002346953A - Power tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power tool that can reduce the size of a housing owing to a reduced number of part items and is easy to hold and use owing to an improved weight balance. SOLUTION: The power tool has the housing l for housing a motor 2 and a fan 3 attached to the motor 2, and a gearbox 5 housing gears for transmitting rotation of the motor. An electronic control circuit 10 for rotational frequency control on the motor 2 is disposed in a substantial center-of-gravity position of the power tool between the motor 2 and the gearbox 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric tool such as an electric circular saw and an electric screwdriver, and more particularly to an electric tool having an electronic control circuit for controlling the number of rotations of a motor.

[0002]

2. Description of the Related Art A conventional power tool will be described with reference to FIGS. FIG. 3 is a front sectional view of a conventional electric circular saw, and FIG. 4 is a side view of the electric circular saw of FIG. As shown in these drawings, inside the housing 10, the motor 20, the fan 30 fixed to the shaft 20a of the motor 20, and the space between the motor 20 and the fan 30, the amount of cooling air generated by the fan 30 is increased. Fan casing 40 is housed. The gear box 5 is located on the side of the fan 30 and is fixed to the housing 10 by screws (not shown) or the like.
In the housing 0, a pinion gear 20b integrally provided at one end of the shaft 20a and a gear 60 which meshes with the pinion gear 20b to change the rotation of the motor 20 are housed. On the upper side of the housing 10, a handle 10a is provided for gripping the electric tool.

Further, a magnetized core 80 and a magnetic sensor 90, which constitute a device for detecting rotation of the motor 20, are provided at a tail portion of the housing 10 opposite to the gear box 50, and a motor. Electronic control circuit 100 for controlling the number of rotations of 20 and electronic control circuit 10
A connector 101 and the like for connecting 0 are attached. An opening 10b is provided in a part of the housing 10 for facilitating the work of attaching these parts, and the opening 10b is covered and covered by a tail cover 70.

[0004]

In the above-mentioned conventional electric power tool, an electronic control circuit for controlling the number of rotations of the motor includes:
In the housing, not only is attached to a tail portion opposite to the gear box side, but also wiring cords and connectors for connecting this electronic control circuit are attached to the same side. Therefore, in the housing, the tail portion must be made large, and a tail cover that covers the opening provided for facilitating the work of assembling these components must be provided. In addition to the increase, there is a problem that the housing also becomes large.

Further, many parts such as an electronic control circuit are gathered in a tail portion of the housing opposite to the gear box side, and the housing itself also has a large tail portion and a heavy weight. When the handle is grasped, it is difficult to hold the handle and it is difficult to use the handle.

[0006] The present invention is intended to solve such a problem, and the number of parts can be reduced, so that the housing can be made smaller and the weight balance is improved, so that it is easy to hold and use. An object of the present invention is to provide a power tool.

[0007]

According to a first aspect of the present invention, there is provided a motor, comprising: a motor;
1 for accommodating a fan 3 mounted on a housing
An electronic control circuit 10 for controlling the number of rotations of the motor 2 in an electric tool having a gear box 5 containing gears for transmitting the rotation of the motor. The power tool is provided substantially at the center of gravity of the power tool.

The invention according to a second aspect is characterized in that the electronic control circuit 10 according to the first aspect is mounted on a fan casing 4 for increasing the cooling efficiency of the fan 3.

[0009]

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

An embodiment according to the present invention is shown in FIGS.
FIG. 1 is a front sectional view of an electric circular saw which is an electric tool of the present embodiment. FIG. 2 is a sectional view of the fan casing 4 of the present invention. The main body of the electric circular saw according to the present embodiment includes a housing 1 and a gear box 5. Housing 1
Is provided with a handle 1a for gripping the electric tool. The handle 1a is provided on or near the center of gravity of the power tool. Housing 1
Inside, a motor 2 having an armature 21 and a field 22 is accommodated with one end of a shaft 2 a thereof being supported by the housing 1 and the other end thereof being supported by the gear box 5.

A ring-shaped magnetizing core 8 is fitted and fixed near the end of the shaft 2a opposite to the gear box 5 side. And it rotates integrally with the shaft 2a. A magnetic sensor 9 is mounted in the housing 1 near the magnetized core 8. The number of rotations of the motor 2 is detected by the magnetized core 8 and the magnetic sensor 9.

A pinion gear 2b is integrally provided at the end of the shaft 2a on the side of the gear box 5, meshes with the gear 6, reduces the rotation of the motor 2, and transmits the rotation to the blade. Further, a fan 3 (in this case, a centrifugal fan) is integrally mounted on the shaft 2a side of the gear box 5 at a fixed distance from the armature 21 by press fitting or the like. In order to cool the motor 2, the fan 3 sucks air from an opening (not shown) provided in a tail portion of the housing 1 opposite to the gear box 5 and sends it out to the gear box 5.

Between the armature 21 and the fan 3, a fan casing 4 whose outer periphery is held by the inner wall of the housing 1 is close to the fan 3, especially at or near the center of gravity of the power tool of the present embodiment. Installed. The fan casing 4 has a ring shape having a hole 4a at the center as shown in FIG. The shaft 2a is provided through the center of the hole 4a. This hole 4
a is made larger than the outer diameter of the armature 21, the fan 3 draws air from an opening (not shown) provided in the tail portion of the housing 1, and the inner diameter of the hole 4a and the shaft Cooling air is sent out to the gear box 5 side through a gap with the outer diameter of 2a.

Further, a ring-shaped groove 4b is provided on a side surface of the fan casing 4. An electronic control circuit 10 in which a triac, a resistor, a capacitor, a diode, an IC, and the like (not shown) are arranged on a substrate (not shown) is attached to the groove 4b. Since the electronic control circuit 10 is mounted on the side surface of the fan casing 4 close to the fan 3, the power control elements in the electronic control circuit 10 can be efficiently cooled.

In the electric power tool according to the present invention, the electronic control circuit 10 is mounted on the fan casing 4 provided substantially at the center of gravity of the electric power tool. And the size of the housing 1 on the side opposite to the gear box 5 can be reduced. Further, the electronic control circuit 10
Since the power tool is provided almost at the center of gravity of the power tool, the weight balance is not deteriorated, and the power tool is easily held.
In addition, a power tool having a good weight balance can be provided regardless of the presence or absence of the electronic control circuit 10.

As shown in FIG. 2, a radius R is provided at a corner of the hole 4a of the fan casing 4 on the motor 2 side. By providing the radius R, the motor 2
The air can be more efficiently sent out from the side of the gear box 5 to the side of the gear box 5.

In this embodiment, when the electronic control circuit is provided, the electric tool in which the fan is provided on the side of the gearbox with respect to the motor has been described. The present invention can also be applied to a power tool provided on the side opposite to the side.

[0018]

As described above, in the electric power tool according to the present invention, the electronic control circuit for controlling the number of revolutions of the motor is provided between the motor and the gearbox and substantially at the center of gravity of the electric power tool. Since the power tool is provided, a power tool having a good weight balance can be provided, and a power tool which is easy to hold and easy to use can be provided. Further, by mounting the electronic control circuit on the fan casing, the number of components can be reduced, and the housing can be reduced in size.

[Brief description of the drawings]

FIG. 1 is a front sectional view of an electric circular saw which is an electric tool according to an embodiment of the present invention.

FIG. 2 is a sectional view of a fan casing according to the embodiment of the present invention.

FIG. 3 is a front sectional view of an electric circular saw according to the related art.

FIG. 4 is a side view of an electric circular saw according to the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Housing 2 Motor 3 Fan 4 Fan casing 5 Gearbox

Claims (2)

[Claims] An electric power tool having a housing for accommodating a motor and a fan attached to the motor, and a gear box for accommodating a gear for transmitting the rotation of the motor, the power tool comprising: An electric tool characterized in that an electronic control circuit for performing the operation is provided between the motor and the gear box and substantially at the center of gravity of the electric tool. 2. An electric tool, wherein the electronic control circuit according to claim 1 is mounted on a fan casing that increases the cooling efficiency of the fan.