JP2003159669A - Power tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power tool that can be selectively used in either operation requiring accuracy or inaccuracy and that facilitates control with good operability without dropping machining accuracy or using other tool. <P>SOLUTION: The power tool features to enable switching on and off an electronic control circuit 4 having a software start circuit that lets an edge tool operate by means of the rotation of a motor 3 and gradually increases the revolution speed of the motor 3 as time goes on after start. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hand-held power tool that can be used properly when performing operations such as cutting and punching using a power tool, depending on the purpose of the work.

[0002]

2. Description of the Related Art Generally, when performing a work such as cutting or drilling, it is not necessary to have an accuracy such as cutting or drilling a rough position, and a predetermined position. There are cases where it is necessary to accurately cut or punch holes.

The power tool in the former case is as follows:
A general electric tool that immediately attains a predetermined rotation speed may be used. On the other hand, the latter electric power tool for accurately cutting or punching a predetermined position is disclosed in Japanese Utility Model Laid-Open No. 57-202684, in which the number of revolutions gradually increases with time after starting. An electric power tool with a soft start circuit that enables increased soft start is disclosed.

Further, Japanese Patent Laid-Open No. 63-251175 discloses a soft start adapter provided with a soft start circuit in addition to an electric power tool, and the power plug of the soft start adapter is inserted into a power outlet. There is disclosed a technique in which an electric tool having no soft start circuit can be soft-started by inserting an insertion plug of the electric tool into an electric tool socket of a soft start adapter.

However, in the former technique, there is a problem in that it is necessary to have an electric power tool used for work that does not require accuracy and an electric power tool used for work that requires accuracy. In other words, if an electric tool that does not have a soft start circuit is used to perform work that requires accuracy, a large reaction or shock at start-up causes the hand holding the electric tool to shake, resulting in misalignment and poor machining accuracy. Could be. On the contrary, if you perform work that does not require accuracy with an electric tool equipped with a soft start circuit,
Although the recoil and the impact at the time of start-up are small, it takes time to reach the optimum number of rotations for the work, and the workability is deteriorated.

In the latter technique, the plug of the electric tool is inserted into the soft start adapter, if necessary,
There is a problem that it has to be removed, workability is poor, and the power tool and the soft start adapter are different, especially the soft start adapter is not used at all times, so it is lost. Easy, etc.
There is a problem that it is not preferable in terms of management.

[0007]

SUMMARY OF THE INVENTION Therefore, the present invention is intended to solve the above-mentioned problems, and one machine can be used for both work that does not require accuracy and work that requires accuracy. The purpose of the present invention is to provide an electric power tool that can be used for a long time and that does not reduce the processing accuracy, has good workability, and is easy to manage.

[0008]

According to a first aspect of the present invention for solving the above problems, the rotation of the motor 3 is used to operate the tip tool, and the rotation speed of the motor 3 is set to An electric power tool provided with an electronic control circuit 4 having a soft start circuit that gradually increases with time is characterized in that the electronic control circuit 4 can be turned on and off.

Next, the invention according to claim 2 relates to claim 1
In the electric power tool described in (1) above, the electronic control circuit 4 is provided with an adjusting means 9 capable of adjusting the time required to reach a predetermined rotation speed after the motor 3 is started by soft start.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit diagram showing a first embodiment of the present invention. FIG. 2 is a circuit diagram showing a second embodiment of the present invention. FIG. 3 is a side view of an electric circular saw equipped with the circuit of the second embodiment.

In FIG. 1, 1 is an AC power source, 2 is a main switch, 3 is a motor, 5 is a sensor provided near the motor 3 for detecting the rotation of the motor, and 4 is a motor 3 based on a signal from the sensor 5. It is an electronic control circuit having a feedback circuit (not shown) for controlling the rotation speed. Further, the electronic control circuit 4 is provided with an IC (not shown) having a soft start circuit for soft starting the motor 3, a triac, a resistor, a capacitor, a diode and the like. And this electronic control circuit 4
A circuit is provided for bypassing. This bypass circuit is provided with a soft start changeover switch 6 for opening and closing this circuit.

In an electric tool having such a circuit,
When performing work that does not require accuracy, the soft start changeover switch 6 is closed so that a current flows through the circuit bypassing the electronic control circuit 4 (soft start off state). When the main switch 2 is turned on in this state, no current flows through the soft start circuit provided in the electronic control circuit 4, and the motor 3 immediately reaches a predetermined rotation speed, which enables quick work.

Next, when performing work requiring accuracy, the soft start changeover switch 6 is opened so that no current flows in the circuit bypassing the electronic control circuit 4 (soft start ON state). When the main switch 2 is turned on in this state, a current flows through the soft start circuit provided in the electronic control circuit 4, and the motor 3 gradually increases its rotation speed with the passage of time, and a predetermined time passes. After that, the predetermined number of rotations is reached. As a result, recoil and impact at the time of start-up are reduced, the hand holding the electric tool is not shaken, and positional deviation does not occur, and accurate work with high processing accuracy is possible. In addition, the operator's concern about machining accuracy and fatigue are reduced.

Next, the circuit of the second embodiment will be described with reference to FIG. The same members as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted. Reference numeral 7 is an electronic control circuit that controls the number of rotations of the motor 3 based on the signal from the sensor 5. Reference numeral 8 is an IC provided in the electronic control circuit 7 and having a soft start circuit (not shown). Reference numeral 61 is a soft start changeover switch connected to the terminal of the IC 8. This soft start switch 61
If is closed and the terminals of IC8 are short-circuited, the soft start circuit will not function. FIG. 2 shows a state in which the soft start changeover switch 61 is opened and the soft start circuit functions. Reference numeral 9 denotes a variable capacitor for soft start adjustment which is arranged in parallel with the soft start changeover switch 61 and is connected to the terminal of the IC 8.

FIG. 3 is a side view showing an electric circular saw provided with the circuit of the second embodiment, and 11 is an electric circular saw body. Two
Is a main switch provided in the electric circular saw body 11, 61
Is a soft start changeover switch, and 10 is a soft start adjustment dial, which is attached to the variable capacitor 9 for soft start adjustment shown in FIG.

In the electric circular saw shown in FIG. 3, on / off (open / close) of the soft start circuit (not shown) can be selected by the soft start changeover switch 61, so that the work which does not require accuracy is performed. Therefore, one electric circular saw can be used properly for tasks that require accuracy. Further, when the soft start adjustment dial 10 is rotated while the soft start changeover switch 61 is open (soft start on), the capacity of the variable capacitor 9 for soft start adjustment changes, and the predetermined number of rotations during soft start. You can adjust the time to reach. Therefore, not only one electric circular saw can be used properly, but more appropriate soft start conditions can be selected according to the inertia of the tip tool, work content, and the like.

In the circuit of this embodiment, an electronic control circuit provided with a feedback circuit of a type in which the rotation speed of the motor is directly detected by a sensor is shown. However, a type of controlling the rotation speed by detecting a current value, or a software It can also be applied to a circuit including a control circuit having only a start circuit. In addition, although the electric circular saw is shown in the present embodiment, the present invention is not limited to the electric power tool,
For example, it can be applied to a drill, a grinder, a driver drill, a jigsaw, a polisher and the like.

[0019]

As described above, according to the power tool of the present invention, in the power tool provided with the electronic control circuit having the soft start circuit for gradually increasing the rotation speed of the motor with the lapse of time after starting, By making it possible to turn on and off the electronic control circuit that has this soft start circuit, it is possible to use it selectively for both work that does not require accuracy and work that requires accuracy with one unit. Therefore, it is possible to provide an electric power tool that has good workability and is easy to manage without lowering the processing accuracy. Also, after the motor is started by soft start in the electronic control circuit,
By making it possible to adjust the time required to reach the predetermined rotation speed, more appropriate soft start conditions can be selected, and the above-mentioned effect can be further enhanced.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a first embodiment of the present invention.

FIG. 2 is a circuit diagram showing a second embodiment of the present invention.

FIG. 3 is a side view of an electric circular saw provided with the circuit of the second embodiment.

[Explanation of symbols]

1 power supply 2 Main switch 3 motor 4, 7 Electronic control circuit 5 sensors 6,61 Soft start changeover switch

Claims (2)

[Claims] 1. A power tool comprising an electronic control circuit having a soft start circuit for operating a tip tool by utilizing rotation of a motor and gradually increasing the number of rotations of the motor with the lapse of time after starting, An electric tool characterized in that the electronic control circuit can be turned on and off. 2. The electric power tool according to claim 1, wherein the electronic control circuit is provided with an adjusting unit capable of adjusting a time until a predetermined rotation speed is reached after the motor is started by soft start. And an electric tool.