MOTOR-DRIVEN APPLIANCE

• US 20150042247A1
• Filed: 07/24/2014
• Published: 02/12/2015
• Est. Priority Date: 08/07/2013
• Status: Active Grant

• Current Assignee: Makita Corporation
• Original Assignee: Makita Corporation
• Inventors: KUSAKAWA, Takuya
• Granted Patent: US 9,866,153 B2
• Time in Patent Office: Days
• US Class Current: 318/139
• CPC Class Codes: B25F 5/00 Details or components of portable power-driven tools not particularly related to the operations performed and not otherwise provided for
• CPC Class Codes: H02P 6/26 Arrangements for controlling single phase motors
• CPC Class Codes: H02P 7/2913 whereby the speed is regulated by measuring the motor speed and comparing it with a given physical value

Abstract

A motor-driven appliance includes a motor and a control unit that controls a drive output to the motor. The control unit detects a state amount indicating an operational state of the motor to derive a fluctuation range of fluctuation in the state amount. The control unit detects whether the motor is in an unloaded state or in a loaded state, based on the derived fluctuation range to perform the drive output to the motor, based on the detected result.

Claims

1. A motor-driven appliance comprising:

a motor; and

a control unit that is configured to control a drive output to the motor, the control unit comprising;

a state amount detection unit that is configured to detect a state amount indicating an operational state of the motor;

a fluctuation range derivation unit that is configured to derive a fluctuation range of fluctuation in the state amount, based on the state amount detected by the state amount detection unit;

a load presence/absence detection unit that is configured to detect whether the motor is in an unloaded state or in a loaded state, based on the fluctuation range derived by the fluctuation range derivation unit; and

a drive output unit that is configured to perform the drive output to the motor, based on the state detected by the load presence/absence detection unit.

2. The motor-driven appliance according to claim 1, wherein the drive output unit is configured to perform the drive output to the motor so that a number of rotations of the motor is larger in the loaded state than in the unloaded state, based on the state detected by the load presence/absence detection unit.

3. The motor-driven appliance according to claim 1,

wherein the control unit comprises:

a fluctuation occurrence determination unit that is configured to determine, at each predetermined determination timing, whether the fluctuation range derived by the fluctuation range derivation unit is equal to or larger than a predetermined fluctuation occurrence detection threshold;

a number-of-fluctuation-detections counting unit that is configured to count a number of fluctuation detections, which is a number of times the fluctuation range is determined by the fluctuation occurrence determination unit to be equal to or larger than the fluctuation occurrence detection threshold; and

a number-of-fluctuation-detections determination unit that is configured to determine whether the number of fluctuation detections counted by the number-of-fluctuation-detections counting unit is equal to or larger than a predetermined number-of-fluctuation-detections threshold, and

wherein the load presence/absence detection unit determines that the motor has been brought into the loaded state if the number of fluctuation detections is determined by the number-of-fluctuation-detections determination unit to be equal to or larger than the number-of-fluctuation-detections threshold.

4. The motor-driven appliance according to claim 3, wherein the control unit comprises a number-of-fluctuation-detections initialization unit that initializes the number of fluctuation detections counted by the number-of-fluctuation-detections counting unit to an initial value if a state in which the fluctuation range is not determined by the fluctuation occurrence determination unit to be equal to or larger than the fluctuation occurrence detection threshold has continued for a predetermined first determination time period.

5. The motor-driven appliance according to claim 3, comprising a threshold setting input unit that is configured to receive a setting input of at least either the fluctuation occurrence detection threshold or the number-of-fluctuation-detections threshold,

wherein the control unit comprises a threshold setting unit that is configured to set the at least either the fluctuation occurrence detection threshold or the number-of-fluctuation-detections threshold inputted by the threshold setting input unit as a setting input value.

6. The motor-driven appliance according to claim 5, wherein the threshold setting input unit comprises at least either an operation input receiving unit that is configured to receive the setting input by operation input to an operation unit provided in the motor-driven appliance or a communication input receiving unit that is configured to receive the setting input by communication from an external device.

7. The motor-driven appliance according to claim 3, comprising:

a battery that is configured to supply electric power to the motor; and

a voltage detection unit that is configured to detect a voltage of the battery,

wherein the control unit comprises a threshold change unit that is configured to change the at least either the fluctuation occurrence detection threshold or the number-of-fluctuation-detections threshold, based on the voltage of the battery detected by the voltage detection unit.

8. The motor-driven appliance according to claim 1, wherein the load presence/absence detection unit determines that the motor has been brought into the loaded state if a state in which the fluctuation range derived by the fluctuation range derivation unit is equal to or smaller than a predetermined no-fluctuation threshold indicating no fluctuation in the state amount has continued for a predetermined second determination time period.

9. The motor-driven appliance according to claim 1, wherein the drive output unit is configured to perform, in the unloaded state, a drive output under no load for rotating the motor at a predetermined number of rotations under no load;

and to perform, in the loaded state, a drive output under load for rotating the motor at a predetermined number of rotations under load that is larger than the number of rotations under no load.

10. The motor-driven appliance according to claim 9, comprising a number-of-rotations setting input unit that is configured to receive a setting input of at least either the number of rotations under no load or the number of rotations under load,

wherein the control unit comprises a number-of-rotations setting unit that is configured to set the at least either the number of rotations under no load or the number of rotations under load inputted by the number-of-rotations setting input unit as a setting input value.

11. The motor-driven appliance according to claim 10, wherein the number-of-rotations setting input unit comprises at least either an operation input receiving unit that is configured to receive the setting input by operation input to an operation unit provided in the motor-driven appliance or a communication input receiving unit that is configured to receive the setting input by communication from an external device.

12. The motor-driven appliance according to claim 9, comprising a selection input receiving unit that is configured to receive, in a case where a change to the unloaded state is detected after a change from the unloaded state to the loaded state has been detected by the load presence/absence detection unit, a selection input as to whether the drive output to the motor by the drive output unit is to be changed from the drive output under load to the drive output under no load, or the drive output under load is to be maintained as it is,

wherein the drive output unit performs, in a case where a change to the unloaded state is detected after a change from the unloaded state to the loaded state has been detected by the load presence/absence detection unit, the drive output to the motor according to input received by the selection input receiving unit.

13. The motor-driven appliance according to claim 12, wherein the selection input receiving unit comprises at least either an operation input receiving unit that is configured to receive the selection input by operation input to an operation unit provided in the motor-driven appliance or a communication input receiving unit that is configured to receive the selection input by communication from an external device.

14. The motor-driven appliance according to claim 1,

wherein the state amount detection unit is configured to detect a current flowing in the motor as the state amount, and

wherein the fluctuation range derivation unit is configured to derive an amplitude of the current detected by the state amount detection unit as the fluctuation range.

15. The motor-driven appliance according to claim 1, comprising:

an appliance element; and

a drive mechanism that is configured to reciprocatingly drive the appliance element by converting a rotation of the motor to a reciprocating movement and transmitting the reciprocating movement to the appliance element,

wherein the appliance element driven reciprocatingly is brought into contact with a workpiece to thereby enable processing of the workpiece.