Articulating drill with optical speed control and method of operation

• US 7,708,085 B2
• Filed: 11/03/2006
• Issued: 05/04/2010
• Est. Priority Date: 11/04/2005
• Status: Active Grant

• Current Assignee: Credo Technology Corporation, Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Pozgay, David, DeCicco, John, Kovarik, Illya
• Primary Examiner(s): Rada; Rinaldi I.
• Assistant Examiner(s): LOW, LINDSAY M
• Application Number:
  US11/592,829
• Publication Number:
  US 20070144872A1
• Time in Patent Office: 1,278 Days
• Field of Search: 173/1, 173/2, 250/214
• US Class Current: 173/176
• 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 power tool includes an optical speed control switch for controlling the variable speed of an electrical motor in the tool. The tool includes a moveable member having a reflective surface and the moveable member traversing a distance between a stop position and a full speed position, a biasing member operatively coupled to the moveable member to bias the moveable member toward the stop position, an optical signal generator for generating an optical signal, the optical signal generator being oriented so that the optical signal is directed toward the reflective surface of the moveable member, and a speed control signal generator for generating a speed control signal that corresponds to a reflection of the generated optical signal reflected by the reflective surface of the moveable member.

Claims

1. A power tool, comprising:

a battery,

a motor having an output shaft,

a bit holder configured to rotate in response to rotation of the output shaft,

a printed circuit board,

a collapsible rubber cover having a reflective surface and defining an interior space in which the reflective surface is located, the collapsible cover being configured to move between a stop position and a full speed position,

a trigger structure movably mounted to the printed circuit board, the collapsible cover being interposed between the trigger structure and the printed circuit board,

a spring supported by the printed circuit board and configured to bias the trigger structure away from the printed circuit board,

an optical signal generator for generating an optical signal, the optical signal generator being oriented so that the optical signal is directed toward the reflective surface to produce a reflected optical signal which is reflected by the reflective surface,

a speed control signal generator having a light sensor and configured to receive the reflected optical signal with the light sensor and generate an analog speed control signal in response thereto that corresponds to an intensity of the reflected optical signal,

a timing signal generator configured to receive the analog speed control signal and generate a digital speed control signal in response thereto that corresponds to a magnitude of the analog speed control signal,

a solid state switching device configured to receive the digital speed control signal and selectively couple the battery to the motor in response thereto so as to rotate the output shaft,

wherein the optical signal generator and the light sensor are both mounted on the printed circuit board,

wherein the collapsible rubber cover is positioned to cover both the optical signal generator and the light sensor, and

wherein the collapsible rubber cover moves between the stop position and the full speed position in response to movement of the trigger structure in relation to the printed circuit board.

2. The tool of claim 1, wherein the optical signal generator is an infrared (IR) signal generator.

3. The tool of claim 2, wherein the speed control signal generator is an optical-transistor.

4. The tool of claim 3, wherein the optical signal generator and the optical-transistor are located in a single housing having a sight glass for emitting an IR signal and receiving a reflected IR signal.

5. The tool of claim 3, wherein the optical signal generator and the optical-transistor are located in a single housing having a first sight glass for emitting an IR signal and a second sight glass for receiving a reflected IR signal.

6. The power tool of claim 1, wherein the reflective surface is mounted to an inside portion of the collapsible rubber cover.

7. The power tool of claim 1, wherein the collapsible rubber cover comprises a collapsible rubber boot.

8. The power tool of claim 1, wherein:

the digital speed control signal includes a timing pulse having a logical on-state corresponding to the magnitude of the analog speed control signal, and

the solid state switching device is coupled to the timing signal generator to receive the timing pulse.

9. The power tool of claim 8, wherein the solid state switching device includes a MOSFET that includes:

a gate coupled to the timing signal generator to receive the timing pulse,

a drain coupled to a terminal of the motor, and

a source coupled to electrical ground.

10. The power tool of claim 9, wherein the solid state switching device couples the drain to the source so that the terminal of the motor is coupled to electrical ground during the logical on-state of the timing pulse.

11. The power tool of claim 1, wherein:

the digital speed control signal is a PWM digital speed control signal, and

the solid state switching device is configured to receive the PWM digital speed control signal and selectively couple the battery to the motor in response thereto.