Motor driven appliance and protection method thereof

Patent metadata

Field	Value
Publication number	US-9634583-B2
Application number	US-201514612626-A
Country	US
Kind code	B2
Filing date	Feb 3, 2015
Priority date	Feb 5, 2014
Publication date	Apr 25, 2017
Grant date	Apr 25, 2017

Abstract

A motor driven appliance in one aspect of embodiments of the present disclosure comprises a motor, a first switching element, a second switching element, an operation unit, a control unit, and a monitoring unit. The first and second switching elements are provided on a current path from a power source to the motor, and are connected in series to each other. The monitoring unit monitors an operating state of a protection function by the control unit, and, when the protection function is activated, outputs an OFF signal for turning off the second switching element.

First claim

What is claimed is:

1. A motor driven appliance comprising:
a motor;
first and second switching elements that are provided on a current path from a power source to the motor, and are connected in series to each other;
an operation unit configured to accept an external operation input for driving the motor;
a control unit configured to activate a control function to output a control signal for turning on the first switching element in accordance with an operating state of the operation unit, and a protection function to stop the output of the control signal irrespective of the operating state of the operation unit when a predetermined protection condition is satisfied while the control signal is being output; and
a monitoring unit configured to monitor an operating state of the protection function by the control unit and, when the protection function is activated, output an OFF signal for turning off the second switching element.

2. The motor driven appliance according to claim 1 ,
wherein the monitoring unit is configured to monitor the operating state of the protection function based on states of at least two monitored objects in the motor driven appliance.

3. The motor driven appliance according to claim 2 ,
wherein a first monitored object of the at least two monitored objects is a monitored object that changes its state in accordance with the operating state of the motor, and
the monitoring unit is configured to output the OFF signal, after the motor starts to be driven, and when the first monitored object is in a state that satisfies a motor stop condition that is a condition under which the motor stops and when a second monitored object of the at least two monitored objects is in a specific state.

4. The motor driven appliance according to claim 3 ,
wherein the second monitored object is the operation unit, and
the specific state comprises a state in which a predetermined operation for driving the motor is made to the operation unit.

5. The motor driven appliance according to claim 3 ,
wherein the motor stop condition comprises a condition that no voltage is applied to the motor necessary to drive the motor.

6. The motor driven appliance according to claim 3 ,
wherein the motor stop condition comprises a condition that the control signal is not being output from the control unit.

7. The motor driven appliance according to claim 3 ,
wherein the first switching element comprises a first terminal and a second terminal, and is configured such that, when the first switching element is turned on, a current to flow from the power source to the motor flows from the first terminal to the second terminal through the first switching element, and
the motor stop condition comprises a condition that a voltage between the first terminal and the second terminal is equal to or greater than a predetermined voltage threshold that is greater than a voltage at which the first switching element is turned on and the motor is driven.

8. The motor driven appliance according to claim 1 , further comprising
a forcing turn-off unit configured to turn off the first switching element irrespective of whether the control signal is being output from the control unit when the OFF signal is being output from the monitoring unit.

9. The motor driven appliance according to claim 1 ,
wherein the monitoring unit is further configured to continue the output of the OFF signal until a specific release condition is satisfied if it outputs the OFF signal.

10. The motor driven appliance according to claim 9 ,
wherein the release condition comprises a condition that the operation unit is operated to a predetermined state for stopping the driving of the motor.

11. A protection method of a motor driven appliance comprising a motor and an operation unit configured to accept an external operation input for driving the motor, the method comprises:
providing first and second switching elements connected in series to each other on a current path from a power source to the motor;
activating a protection function to turn off the first switching element thereby to stop the motor irrespective of an operating state of the operation unit when a predetermined protection condition is satisfied; and
monitoring an operating state of the protection function to turn off the second switching element when the protection function is activated.

12. A protection method of a motor driven appliance comprising a motor and an operation unit configured to accept an external operation input for driving the motor, the method comprises:
providing first and second switching elements connected in series to each other on a current path from a power source to the motor;
activating a protection function to turn off the first switching element thereby to stop the motor irrespective of an operating state of the operation unit when a predetermined protection condition is satisfied; and
monitoring an operating state of the protection function to output an OFF signal for turning off the second switching element when the protection function is activated.

Assignees

• Makita Corp

Inventors

• Suda Hidekazu

Classifications

• H02P3/02 Primary

  Details {of stopping control} · CPC title

• H02P29/0241 Primary

  the fault being an overvoltage · CPC title