Method of operating drill with solid state speed control

• US 7,861,796 B2
• Filed: 02/09/2009
• Issued: 01/04/2011
• Est. Priority Date: 11/04/2005
• Status: Expired due to Fees

• Current Assignee: Credo Technology Corporation, Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Pozgay, David, DeCicco, John, Kovarik, Illya
• Primary Examiner(s): Smith; Scott A.
• Application Number:
  US12/367,698
• Publication Number:
  US 20090148139A1
• Time in Patent Office: 694 Days
• Field of Search: 173/176, 173/1, 173/2, 173/217, 173/171, 173/213, 318/376, 318/808, 318/268, 318/254, 318/798, 318/810, 318/438, 318/432, 310/47, 310/50
• US Class Current: 173/1
• CPC Class Codes: B25B 21/00 Portable power-driven screw or nut setting or loosening tools; details or components, e.g. casings, bodies, of portable power-driven tools not particularly related to the operation performed B25F5/00; for mounting or dismounting wheels B60B29/006; Attachments for drilling apparatus serving the same purpose machines B23P19/06
• CPC Class Codes: B25B 23/14 Arrangement of torque limiters or torque indicators in wrenches or screwdrivers couplings for transmitting rotation or clutches F16D; devices for measuring torque per se G01L
• CPC Class Codes: B25F 5/02 Construction of casings, bodies or handles B25F5/006, B25F5/008 take precedence
• CPC Class Codes: H01H 9/061 enclosing a continuously variable impedance
• CPC Class Codes: H02P 7/29 using pulse modulation
• CPC Class Codes: Y10S 388/937 Hand tool

Abstract

A method of operating a hand power tool in one embodiment includes generating a variable speed control signal with a solid state switch that corresponds to a selected speed for a motor, generating a pulse width modulated (PWM) signal corresponding to the variable speed control signal, generating H-bridge driving signals for an H-bridge circuit in correspondence with the PWM signal, and selectively coupling a motor to a power source using the H-bridge circuit in accordance with the H-bridge driving signals.

Claims

1. A method of operating a hand power tool comprising:

generating a variable speed control signal with a solid state switch in correspondence with a reflected optical signal that corresponds to a selected speed for a motor;

generating a pulse width modulated (PWM) signal corresponding to the variable speed control signal;

generating H-bridge driving signals for an H-bridge circuit in correspondence with the PWM signal;

selectively coupling a motor to a power source using the H-bridge circuit in accordance with the H-bridge driving signals;

traversing a moveable member having a reflective surface through a distance between a stop position and a full speed position;

biasing the moveable member toward the stop position; and

directing an optical signal toward the reflective surface of the moveable member to generate the reflected optical signal.

2. The method of claim 1 further comprising:

generating a dynamic braking signal in response to a motor torque signal being equal to or greater than a torque limit signal; and

generating H-bridge driving signals for the H-bridge circuit that correspond to the dynamic braking signal.

3. The method of claim 2, the dynamic braking signal generation including:

generating a rectangular waveform.

4. The method of claim 3, the rectangular waveform generation including:

generating a rectangular waveform having an off-state of at least about 200 μ

seconds.

5. The method of claim 2 further comprising:

inverting a motor direction control signal; and

reversing a polarity of a battery coupled to the motor in response to the inverted motor direction control signal during an off-state of the rectangular waveform.

6. The method of claim 2 further comprising:

inverting a motor direction control signal; and

disabling the dynamic brake signal generation in response to the motor direction control signal being inverted.

7. A method of operating a hand power tool comprising:

biasing a moveable member having a reflective surface toward a stop position;

forcing the biased moveable member toward a full speed position;

generating an optical signal;

reflecting the optical signal off of the reflective surface;

generating a variable speed control signal that corresponds to the reflected optical signal;

generating a pulse width modulated (PWM) signal corresponding to the variable speed control signal;

generating H-bridge driving signals corresponding to the PWM signal; and

selectively coupling a motor to a power source in accordance with the H-bridge driving signals.

8. The method of claim 7 further comprising:

generating a motor torque signal; and

generating a dynamic braking signal for the H-bridge circuit in response to the motor torque signal being equal to or greater than a torque limit signal.

9. The method of claim 8, wherein generating dynamic braking signals comprises:

generating a dynamic braking signal having a rectangular waveform.

10. The method of claim 9, wherein generating dynamic braking signals comprises:

generating a rectangular waveform having an off-state of at least about 200 μ

seconds for the dynamic braking signal.

11. The method of claim 9, wherein generating dynamic braking signals comprises:

generating a rectangular waveform having a frequency of about 30 Hz.

12. The method of claim 7, further comprising:

generating a dynamic braking signal with an off-state;

providing a motor direction control signal;

inverting the motor direction control signal;

coupling the inverted motor direction control signal to a driver circuit; and

reversing a battery polarity coupled to the motor after the off-state of the dynamic braking signal.

13. A method of operating a hand power tool comprising:

positioning a moveable member having a reflective surface at a location between a stop position and a full speed position;

reflecting an optical signal off of the reflective surface of the positioned moveable member;

generating a variable speed control signal based upon the reflected optical signal;

generating a pulse width modulated (PWM) signal based upon the variable speed control signal;

generating H-bridge driving signals based upon the PWM signal; and

coupling a motor to a power source based upon the H-bridge driving signals.

14. The method of claim 13 further comprising:

generating a motor torque signal;

generating a dynamic braking signal in response to the motor torque signal being equal to or greater than a torque limit signal; and

generating H-bridge dynamic braking signals for the H-bridge circuit corresponding to the dynamic braking signal.

15. The method of claim 14, wherein generating dynamic braking signals comprises:

generating a dynamic braking signal having a rectangular waveform.

16. The method of claim 15, wherein generating dynamic braking signals comprises:

generating a rectangular waveform having an off-state of at least about 200 μ

seconds for the dynamic braking signal.

17. The method of claim 16, wherein generating dynamic braking signals comprises:

generating a rectangular waveform having a frequency of about 30 Hz.

18. The method of claim 13, further comprising:

providing a motor direction control signal;

inverting the motor direction control signal;

coupling the inverted motor direction control signal to a driver circuit; and

reversing a battery polarity coupled to the motor after the off-state of the dynamic braking signal.