Control device for variable speed electric motors, particularly for power tools

Abstract

A control device for a variable speed motor of an electric tool, comprising an electronic drive unit connected to a terminal of a power supply to supply power to at least one motor, and an optical switch device triggers the electronic drive unit. The optical switching device comprises a light emitting device and a light converting device which detects the light and converts the light into an electronically changed signal, the light converting device is connected to an electronic drive unit for controlling at least one motor, wherein the light emitting device comprises at least one light emitting diode via a small power circuit Connected in parallel to the power terminal, the at least one light emitting diode is a white light, high brightness light emitting diode, when the motor is a DC motor, an input resistance is included in the small power supply circuit to protect the at least one light emitting diode Diode, when the motor is an AC motor, at least one capacitor is included in the small power supply circuit to generate capacitive phase shift by converting the voltage phase and current phase to make them differ by 90 degrees, so that the electric energy wasted by the capacitor is zero.

Description

technical field [0001] The invention relates to a control device for controlling a variable speed motor. The control device of the present invention is especially used in the field of hand-held electric tools, such as electric drills, hammer drills, electric circular saws, reciprocating saws, jig saws, electric wood milling, electric planers, sanders and sanders, etc., as well as other small electric tools. instrument. Background technique [0002] The trigger of the operating control is usually mounted on the handle of the power tool so that the operator can operate the trigger with one or more fingers while holding the tool. This control device operates the power tool by starting the motor and adjusting its speed from zero to maximum. [0003] The control devices mentioned above generally include a mechanical main switch to connect the main power supply to a control circuit, the variable resistor or potentiometer is mechanically connected to the control device, and the p...

AI Technical Summary

Problems solved by technology

However, the use of such devices has so far been limited to single-color LEDs (such as red, green, or yellow), whose limited spectrum makes it difficult to drive receiving devices unless multiple LEDs are used to increase light intensity

Obviously, using multiple LEDs can have a big impact on the size of the trigger switch

[0022] There is also a disadvantage in these solutions related to the power supply circuit

In fact, the working voltage of LEDs is very low (about 2 volts), which requires a transformer to continuously reduce the main voltage (110 / 230V), and such a transformer will be difficult to fit into a hand-held power tool due to size constraints

Another way to power the LEDs is to use a resistor divider, but this method also has a heat dissipation problem and wastes more power

Moreover, the use of multiple LEDs produces a large beam, requiring the use of a large shutter, which is difficult to fit into a limited space

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