Control drive circuit for electric power tool

Abstract

In a control drive circuit for an electric power tool, a bridge-structured motor, which has a bridge structure and includes switching elements and a motor body, is connected to a power supply unit without any mechanical contacts, and an electric power is supplied to a control circuit for controlling the switching elements by turning on a trigger switch. Further, a circuit switch is provided at power supply sides of drive circuits for driving the switching elements, the circuit switch being controlled by the control circuit to interrupt supply of the electric power to the drive circuits.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects and features of the present invention will become apparent from the following description of embodiments, given in conjunction with the accompanying drawings, in which:

FIG. 1 is a circuit diagram showing a control drive circuit in accordance with an embodiment of the present invention;

FIG. 2 illustrates a circuit diagram showing a control drive circuit in accordance with another embodiment of the present invention; and

FIG. 3 depicts a circuit diagram showing a conventional control drive circuit.

Claims

1. A control drive circuit for an electric power tool, wherein a motor, which has a bridge structure and includes switching elements and a motor body, is connected to a power supply unit without any mechanical contacts, and an electric power is supplied to a control circuit for controlling the switching elements by turning on a trigger switch, andwherein a circuit switch is provided at power supply sides of drive circuits for driving the switching elements, the circuit switch being controlled by the control circuit to interrupt supply of the electric power to the drive circuits.

2. The control drive circuit of claim 1, wherein the supply of the electric power to the control circuit is interrupted after the circuit switch has been turned off.

3. The control drive circuit of claim 1, wherein the circuit switch is turned on after the electric power has been supplied to the control circuit.

4. The control drive circuit of claim 1, wherein the circuit switch is provided at either or both of an upper and a lower portion in the bridge structure.

5. The control drive circuit of claim 1, wherein the circuit switch is turned off after a lapse of time required for a braking operation in turning off the motor.

6. The control drive circuit of claim 1, wherein the circuit switch is connected in anti-parallel with a diode.

7. A control drive circuit for an electric power tool, wherein a motor, which has a bridge structure and includes switching elements and a motor body, is connected to a power supply unit without any mechanical contacts, and an electric power is supplied to a control circuit for controlling the switching elements by turning on a trigger switch, andwherein forcible turn-off units for forcibly turning off the switching elements according to an output of the control circuit are provided.