Controlled power fade for battery powered devices

• US 9,071,069 B2
• Filed: 04/06/2011
• Issued: 06/30/2015
• Est. Priority Date: 04/07/2010
• Status: Active Grant

• Current Assignee: Black & Decker Incorporated (Stanley Black & Decker, Inc.)
• Original Assignee: Black & Decker Incorporated (Stanley Black & Decker, Inc.)
• Inventors: Brotto, Daniele C., Forster, Michael K., Leh, Jason K., Lin, Wing W.
• Primary Examiner(s): Ro, Bentsu
• Assistant Examiner(s): DINH, THAI T
• Application Number:
  US13/080,712
• Publication Number:
  US 20110248653A1
• Time in Patent Office: 1,546 Days
• Field of Search: 318/139, 318/430, 318/443, 318/454, 318/455, 318/471, 318/478, 318/479, 318/490, 320/116, 320/118, 320/132, 320/134, 320/145, 324/429, 324/431, 324/433
• US Class Current: 1/1
• 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: B25F 5/02 Construction of casings, bodies or handles B25F5/006, B25F5/008 take precedence
• CPC Class Codes: B25F 5/021 with guiding devices guiding devices for hand tools on stands or supports B25H1/0078
• CPC Class Codes: G01R 31/3646 for indicating electrical conditions or variables, e.g. visual or audible indicators
• CPC Class Codes: G01R 31/374 with means for correcting the measurement for temperature or ageing
• CPC Class Codes: G01R 31/3835 involving only voltage measurements
• CPC Class Codes: G01R 31/385 Arrangements for measuring battery or accumulator variables for monitoring G01R31/382
• CPC Class Codes: H01H 2009/065 Battery operated hand tools in which the battery and the switch are directly connected
• CPC Class Codes: H01H 9/061 enclosing a continuously variable impedance
• CPC Class Codes: H01M 10/441 for several batteries or cells simultaneously or sequentially
• CPC Class Codes: H01M 10/448 End of discharge regulating measures
• CPC Class Codes: H01M 2010/4271 Battery management systems including electronic circuits, e.g. control of current or voltage to keep battery in healthy state, cell balancing
• CPC Class Codes: H01M 2010/4278 Systems for data transfer from batteries, e.g. transfer of battery parameters to a controller, data transferred between battery controller and main controller
• CPC Class Codes: H01M 2220/30 Batteries in portable systems, e.g. mobile phone, laptop
• CPC Class Codes: H01M 50/569 Constructional details of current conducting connections for detecting conditions inside cells or batteries, e.g. details of voltage sensing terminals battery terminal connectors with integrated measuring arrangements G01R31/364
• CPC Class Codes: H01R 12/7005 Guiding, mounting, polarizing or locking means; Extractors for printed circuit boards H05K
• CPC Class Codes: H01R 13/112 forked sockets having two legs
• CPC Class Codes: H02J 7/00034 Charger exchanging data with an electronic device, i.e. telephone, whose internal battery is under charge
• CPC Class Codes: H02J 7/00041 in response to measured battery parameters, e.g. voltage, current or temperature profile
• CPC Class Codes: H02J 7/0013 acting upon several batteries simultaneously or sequentially H02J7/1423 takes precedence
• CPC Class Codes: H02J 7/0019 : using switched or multiplexed charge circuits
• CPC Class Codes: H02J 7/0025 : Sequential battery discharge in systems with a plurality of batteries
• CPC Class Codes: H02J 7/0029 : with safety or protection devices or circuits
• CPC Class Codes: H02J 7/00306 : Overdischarge protection
• CPC Class Codes: H02J 7/0031 : using battery or load disconnect circuits H02J9/002 takes precedence
• CPC Class Codes: H02J 7/0045 : concerning the insertion or the connection of the batteries
• CPC Class Codes: H02J 7/0048 : Detection of remaining charge capacity or state of charge [SOC]
• CPC Class Codes: H02J 7/0063 : with circuits adapted for supplying loads from the battery
• CPC Class Codes: H02J 7/00714 : in response to battery charging or discharging current
• CPC Class Codes: H02J 7/007182 : in response to battery voltage
• CPC Class Codes: H02P 3/08 : for stopping or slowing a dc motor
• CPC Class Codes: H02P 31/00 : Arrangements for regulating or controlling electric motors not provided for in groups H02P1/00 - H02P5/00, H02P7/00 or H02P21/00 - H02P29/00
• CPC Class Codes: H02P 7/285 : controlling armature supply only
• CPC Class Codes: H02P 7/29 : using pulse modulation
• CPC Class Codes: Y02E 60/10 : Energy storage using batteries
• CPC Class Codes: Y02P 70/50 : Manufacturing or production processes characterised by the final manufactured product

Abstract

A method is provided for operating a power tool having a motor powered by a battery. The method includes: delivering power from the battery to the motor in accordance with an operator input; detecting a condition of the power tool indicating a shutdown of the power is imminent; and fading the power delivered from the battery to the motor, in response to the detected condition, through the use of a controller residing in the power tool.

Claims

1. A method for operating a power tool having a motor powered by a battery pack, comprising:

setting the duty cycle of a pulse width modulated control signal in accordance with a position of the trigger switch;

delivering power from the battery pack to the motor in accordance with the control signal, the battery pack having a positive terminal, a negative terminal, and a temperature sense terminal, the battery pack housing a battery coupled to the positive and negative terminals and a temperature sensor arranged between the positive terminal and the temperature sense terminal;

monitoring a temperature of battery pack using a signal received from the temperature sensor via the temperature sense terminal; and

fading the power delivered from the battery to the motor when the temperature exceeds a temperature fade threshold, through the use of a controller residing in the power tool, wherein the fading step comprises;

computing a value of the duty cycle as a function of a value of the temperature,

and

setting the duty cycle of the control signal to the computed value of the duty cycle when the computed value of the duty cycle is less than the duty cycle set in accordance with position of the trigger switch, and retaining the duty cycle set in accordance with the position of the trigger switch when the computed value of the duty cycle is more than the duty cycle set in accordance with the position of the trigger switch.

2. The method of claim 1 further comprises fading the power delivered by an amount that is computed as a function of a value of the temperature.

3. The method of claim 1 wherein fading of the power delivered further comprises decreasing the power delivered as a function of the value of the temperature, where the function is at least one of linear, step, exponential or polynomial.

4. The method of claim 1 further comprises delivering power to the motor in accordance with position of a trigger switch on the tool.

5. The method of claim 1 further comprises decreasing the power delivered linearly as a function of the temperature until the temperature exceeds a temperature cutoff threshold.

6. The method of claim 1 wherein the pulse width modulated control signal is sent from the controller to a control terminal of a switch disposed in series with the battery.

7. A power tool system comprising:

a tool assembly having a motor;

a battery pack that selectively couples to the tool assembly and includes a positive terminal, a negative terminal, and a temperature sense terminal that interface with the tool assembly, wherein the battery pack houses a battery that provides power to the motor via the positive and negative terminals and a thermistor arranged between the positive terminal and the temperature sense terminal;

a trigger switch disposed on the tool assembly; and

a discharge control module within the tool assembly that controls power delivered from the battery to the motor by setting a duty cycle of a pulse width modulated control signal of a switch disposed in series with the battery in accordance with a position of the trigger switch, the discharge control module being further configured to monitor a temperature in the battery pack using a signal from the thermistor received via the temperature sense terminal, and fade the power delivered from the battery to the motor by an amount that is computed as a function of a value of the temperature by adjusting the duty cycle of the control signal, wherein the discharge control module sets the duty cycle of the control signal to a value computed as a function of a value of the temperature when the computed value of the duty cycle is less than the duty cycle set in accordance with position of the trigger switch, and retains the duty cycle of the control signal set in accordance with the position of the trigger switch when the computed value of the duty cycle is more than the duty cycle set in accordance with the position of the trigger switch.

8. The power tool system of claim 7 wherein the discharge control module fades the power delivered by decreasing the power delivered as a function of the value of the temperature, where the function is at least one of linear, step, exponential or polynomial.

9. The power tool system of claim 7 wherein the discharge control module initiates fading of the power delivered when the temperature exceeds a temperature fade threshold and decreases the power delivered linearly as a function of the temperature until the temperature exceeds a temperature cutoff threshold.

10. A method for operating a power tool having a motor powered by a battery pack, comprising:

delivering power from the battery pack to the motor in accordance with an operator input;

monitoring a temperature of battery pack using a temperature sensor electronically coupled to a positive terminal of the battery pack; and

fading the power delivered from the battery to the motor when the temperature exceeds a temperature fade threshold, through the use of a controller residing in the power tool,

wherein monitoring a temperature includes;

monitoring voltage across the temperature sensor;

monitoring voltage of the battery in the battery pack;

calculating a ratio between the voltage across the temperature sensor and the voltage of the battery in the battery pack; and

determining the temperature using the calculated ratio.

11. The method of claim 10 further comprised retrieving the temperature from a data store using the calculated ratio.

12. A power tool system comprising:

a tool assembly having a motor;

a battery pack that selectively couples to the tool assembly and houses a battery that provides power to the motor;

a discharge control module that monitors a temperature in the battery pack using a thermistor disposed in the battery pack and fades the power delivered from the battery to the motor by an amount that is computed as a function of a value of the temperature, wherein the thermistor is electrically coupled to a positive terminal of the battery and accessible to the discharge control module, and wherein the discharge control modules determines the temperature in the battery pack by monitoring voltage across the thermistor, monitoring voltage across the battery in the battery pack, calculating a ratio between the voltage across the thermistor and the voltage of the battery in the battery pack, and determines the temperature using the calculated ratio.

13. The power tool of claim 12, wherein the discharge control module retrieves the temperature from a data store using the calculated ratio.