Control and protection methodologies for a motor control module

• US 7,817,384 B2
• Filed: 05/20/2009
• Issued: 10/19/2010
• Est. Priority Date: 10/12/2005
• Status: Expired due to Fees

• Current Assignee: Black & Decker Incorporated (Stanley Black & Decker, Inc.)
• Original Assignee: Black & Decker Incorporated (Stanley Black & Decker, Inc.)
• Inventors: Kalbfleisch, William G., Privett, Zollie W., Woods, Samuel G., Forster, Michael K., Leh, Jason K., Beers, David R., Vanko, John C., Gallagher, William F., Usselman, Robert A.
• Primary Examiner(s): Leykin; Rita
• Application Number:
  US12/469,376
• Publication Number:
  US 20090224703A1
• Time in Patent Office: 517 Days
• Field of Search: 361/33, 361/87, 318/432, 318/434
• US Class Current: 361/33
• CPC Class Codes: B24B 23/028 Angle tools
• CPC Class Codes: B24B 55/00 Safety devices for grinding or polishing machines; Accessories fitted to grinding or polishing machines for keeping tools or parts of the machine in good working condition of general applicability for machine tools B23Q11/00; in general F16P
• CPC Class Codes: H02H 5/04 responsive to abnormal temperature specially adapted for electric machines H02H7/0852
• CPC Class Codes: H02H 7/08 for dynamo-electric motors
• CPC Class Codes: H02K 11/33 Drive circuits, e.g. power electronics H02K11/38 takes precedence
• CPC Class Codes: H02M 5/2573 with control circuit
• CPC Class Codes: H02P 25/14 Universal motors H02P25/12 takes precedence
• CPC Class Codes: H02P 29/02 Providing protection against overload without automatic interruption of supply protection against faults of stepper motors H02P8/36
• CPC Class Codes: Y10T 408/65 Means to drive tool

Abstract

A motor control module designed to control operation of a plurality of different motors in a plurality of different tools a power tool uses an electronic clutch in the module in conjunction with a mechanical clutch in the tool to protect the tool against an overload event. The module is adapted to implement methods to provide aural and/or tactile feedback to a tool user as a warning of an impending or current fault condition in the tool. The module can prevent power from inadvertently turning on either after an overload event has cleared with the tool plugged in and its power switch on, or after plugging in the tool within the power switch on. The control module is adapted to provide torque control for the power tool, to estimate tool motor temperature and to inform a tool user when a servicing need in the tool is required.

Claims

1. A method of estimating tool motor temperature of a tool motor in a corded power tool, comprising:

comparing a motor current value representing an estimate of what temperature the tool'"'"'s motor will be after a given time period has elapsed, assuming constant current, to a temperature register value representing an estimate of the motor temperature at a present point in time, and

updating the temperature register value based on the comparison so that the temperature register value equals the motor current value after the given time period has elapsed wherein upon tool startup, an initial temperature register value is determined by

retrieving stored temperature data at the previous tool shutdown from a memory of a controller in the tool, the stored temperature data including a latest temperature register value at the last tool shutdown and a latest controller temperature at the last shutdown, after a given delay upon tool startup, determining controller temperature at startup, and

comparing the determined controller temperature at startup to the stored controller temperature to determine the initial temperature register value.

2. The method of claim 1, wherein determining controller temperature at startup includes measuring controller temperature at startup from a sensor.

3. The method of claim 1, wherein determining controller temperature at startup includes estimating controller temperature at startup based on a junction voltage of an active electronic device in the power tool.

4. The method of claim 1, wherein the initial temperature register value is set to zero if controller temperature at startup is less than stored controller temperature.

5. The method of claim 1, wherein the initial temperature register value on startup is set to the latest stored temperature register value if controller temperature at startup is within a given margin to the latest stored controller temperature at the previous tool shutdown.

6. The method of claim 1, wherein a first preload value stored in memory is set as the initial temperature register value if the comparison step indicates a warm controller at startup and a second preload value stored in memory is set as the initial temperature register value if the comparison step indicates a hot controller at startup.

7. The method of claim 1, wherein updating the temperature register value includes increasing the temperature register value if the motor current value is greater than the temperature register value or decreasing the temperature register value if the motor current value is less than the temperature register value.