ELECTRIC WORKING MACHINE

• US 20170302211A1
• Filed: 04/11/2017
• Published: 10/19/2017
• Est. Priority Date: 04/18/2016
• Status: Active Grant

• Current Assignee: Makita Corporation
• Original Assignee: Makita Corporation
• Inventors: NAKAMOTO, Akihiro, KATO, Itsuku, KAWAI, Yuki
• Granted Patent: US 10,541,636 B2
• Time in Patent Office: Days
• CPC Class Codes: B23D 45/16 Hand-held sawing devices with circular saw blades
• CPC Class Codes: B23D 47/12 of drives for circular saw blades
• CPC Class Codes: B23D 59/001 Measuring or control devices, e.g. for automatic control of work feed pressure on band saw blade measuring in general G01; controlling in general G05
• CPC Class Codes: B27B 9/00 Portable power-driven circular saws for manual operation details or components, e.g. handles, casings, of portable power-driven tools not particularly related to the operation performed B25F5/00
• CPC Class Codes: H02M 1/083 for the ignition at the zero crossing of the voltage or the current
• CPC Class Codes: H02M 1/322 Means for rapidly discharging a capacitor of the converter for protecting electrical components or for preventing electrical shock
• CPC Class Codes: H02M 7/06 using discharge tubes without control electrode or semiconductor devices without control electrode
• CPC Class Codes: H02P 2201/03 AC-DC converter stage controlled to provide a defined DC link voltage
• CPC Class Codes: H02P 2207/05 Synchronous machines, e.g. with permanent magnets or DC excitation
• CPC Class Codes: H02P 27/06 using dc to ac converters or inverters H02P27/05 takes precedence
• CPC Class Codes: H02P 3/18 for stopping or slowing an ac motor
• CPC Class Codes: H02P 3/22 by short-circuit or resistive braking

Abstract

An electric working machine of an example of the present disclosure includes: a motor; a power supply portion; a controller; and a voltage detector. The power supply portion generates a DC voltage to drive the motor by rectifying an AC voltage supplied from an AC power source and smoothing by a capacitor. The controller controls energization of the motor. The voltage detector detects the AC voltage. The controller is configured to interrupt the energization when the voltage detector does not detect the AC voltage.

Claims

1. An electric working machine comprising:

a motor;

a power supply portion to generate a DC voltage to drive the motor by rectifying an AC voltage supplied from an AC power source and smoothing by a capacitor;

a controller that controls energization of the motor from the power supply portion; and

a voltage detector that detects the AC voltage,

wherein the controller is configured to interrupt the energization when the voltage detector does not detect the AC voltage.

2. The electric working machine according to claim 1, wherein the voltage detector is configured to detect a zero-cross point of the AC voltage.

3. The electric working machine according to claim 1, further comprising:

a voltage generator that receives the DC voltage outputted from the power supply portion via the capacitor and generates a drive voltage to drive the controller.

4. The electric working machine according to claim 1, further comprising:

a discharger that discharges an electric charge of the capacitor following a command of the controller,

wherein the controller is configured to output the command to the discharger and allows the discharger to discharge the electric charge of the capacitor when the voltage detector does not detect the AC voltage.

5. The electric working machine according to claim 4, wherein the discharger includes a first resistor and a transistor that is turned to an on state in response to a command from the controller and connects the first resistor to the capacitor in parallel.

6. The electric working machine according to claim 5, further comprising:

a second resistor connected to the capacitor in parallel,

wherein a resistance value of the first resistor is smaller than a resistance value of the second resistor.

7. The electric working machine according to claim 1, wherein

the power supply portion includes a diode bridge that rectifies the full waves of the AC voltage inputted from the AC power source and the capacitor that smooths rectified electric current.