Speed controller for portable electric cutting tool

Abstract

An electric circular saw (A) having a soft start function with which the rotational speed of a motor (9) reaches a preset speed in a constant speed operation region after a predetermined soft start time after the start of the motor. Response of rotational speed feedback control applied to the motor (9) is slowed and overshoot control is performed at a point after the start of the motor (9) at which point the motor operation is changed from an acceleration operation region to a constant speed operation region, where the overshoot control is control for forcibly allowing the speed of the motor (9) to exceed set speed that is most appropriate for cutting and then allowing the speed to decrease to the set speed. Consequently, reaction opposite to that occurring while motor operation is changed from the acceleration operation region to the constant speed operation region is suppressed without extending the soft start time, and as a result, workability and operability of the electric circular saw (A) are enhanced.

Description

Speed ​​control device for portable electric cutting tools technical field The invention relates to a speed control device of a portable electric cutting tool, especially with a soft start function. Background technique Portable electric cutting tools such as electric circular saws have a large reaction when the motor is started. Therefore, conventionally, in speed control of a motor, for example, a method of suppressing the reaction of the motor by performing a control called a soft start function for 0.7 to 2 seconds from startup is generally known. This soft start function, while suppressing the reaction (opposite to the rotation direction of the motor) at the start, also suppresses the sudden lack of acceleration when moving from the acceleration operation area (soft start area) to the constant speed operation area. , the opposite reaction to the start-up. On the other hand, when the soft start is completed and turns to the constant speed operation area, as a transi...

AI Technical Summary

Problems solved by technology

However, in contrast to this, in the case of an electric cutting tool (such as an electric circular saw, etc.) that is frequently turned on / off, if the soft start time to reach the constant speed operation area is lengthened, this part will reach the most suitable starting point. The time in the constant-speed operation region of the power-off speed (set speed), that is, the waiting time from the start of the most suitable speed to the start of the work becomes longer, and the workability becomes very bad.

Also, when eliminating or reducing the occurrence of excessive movement like Patent Document 1, the above-mentioned opposite reaction will occur and cannot be eliminated or reduced due to excessive

In particular, in a bladed tool with a large diameter and weight such as an electric circular saw, at point C when the acceleration operation region moves to a constant speed operation region, a large force is generated on the bladed tool due to the inertia of the bladed tool. The acceleration quickly becomes zero, and thus, the opposite reaction (the force to raise the front side of the circular saw with the point of the handle as the fulcrum) opposite to the reaction at startup (the force to lower the front side of the circular saw with the point of the handle as the fulcrum) is generated. Force), the opposite reaction at this time is caused by the above-mentioned non-produced or reduced motion, which cannot be suppressed (offset)

For this reason, deterioration of operability cannot be avoided

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