OPTICAL TORQUE SENSOR

• US 20080060451A1
• Filed: 09/12/2007
• Published: 03/13/2008
• Est. Priority Date: 09/12/2006
• Status: Active Grant

• Current Assignee: Black & Decker Incorporated (Stanley Black & Decker, Inc.)
• Original Assignee: Black & Decker Incorporated (Stanley Black & Decker, Inc.)
• Inventors: Puzio, Daniel
• Granted Patent: US 7,591,195 B2
• Time in Patent Office: Days
• US Class Current: 73/862.324
• CPC Class Codes: B25B 23/1456 having electrical components
• CPC Class Codes: B25B 23/147 specially adapted for electrically operated wrenches or screwdrivers
• CPC Class Codes: G01L 3/12 involving photoelectric means
• CPC Class Codes: G01L 3/1421 using optical transducers

Abstract

A torque sensor that includes a sensor housing, a sensor input member at least partially received in the sensor housing, a sensor output member at least partially received in the sensor housing, a torsionally resilient coupling member that couples the sensor input member to the sensor output member and an optical sensor system that includes a light source, one or more encoders and one or more optical sensors. The encoder or encoders periodically transmit light between the light source and the at least one optical sensor based on an amount of relative rotation between the sensor input member and the sensor output member.

Claims

1. A torque sensor comprising:

a sensor housing;

a sensor input member at least partially received in the sensor housing;

a sensor output member at least partially received in the sensor housing;

a torsionally resilient coupling member that couples the sensor input member to the sensor output member; and

an optical sensor system that includes a light source, at least one encoder and at least one optical sensor, the at least one encoder periodically transmitting light between the light source and the at least one optical sensor based on an amount of relative rotation between the sensor input member and the sensor output member.

2. The torque sensor of claim 1, wherein the at least one optical sensor is a single optical sensor.

3. The torque sensor of claim 1, wherein the at least one encoder includes a first encoder wheel that is coupled for rotation with the sensor input member.

4. The torque sensor of claim 3, wherein the at least one encoder includes a second encoder wheel that is coupled for rotation with the sensor output member.

5. The torque sensor of claim 4, wherein the first and second encoder wheels are spaced apart from one another along a rotational axis of the sensor input member.

6. The torque sensor of claim 1, wherein the at least one encoder includes an annular ring with a plurality of circumferentially spaced apart teeth.

7. The torque sensor of claim 6, wherein the at least one encoder includes an aperture that is formed through the sensor output member.

8. The torque sensor of claim 7, wherein an annular light guide is disposed about the sensor output member.

9. The torque sensor of claim 8, wherein a second annular light guide is disposed inwardly of the annular ring.

10. The torque sensor of claim 1, wherein the coupling member includes a torsion spring that is formed of wire.

11. The torque sensor of claim 1, wherein the optical sensor system is an incremental encoder.

12. A torque sensor comprising:

a rotatable sensor input member;

a rotatable sensor output member;

a torsionally resilient coupling member that couples the sensor input member to the sensor output member; and

an optical sensor system that employs light to correlate relative rotation between the sensor input member and the sensor output member to a magnitude of a torque that is transmitted through the torque sensor.

13. The torque sensor of claim 12, wherein the optical sensor system is an incremental encoder.

14. The torque sensor of claim 12, wherein the optical sensor system includes a first encoder member and a second encoder member, the first and second encoder members cooperating to permit transmission of light between a light source and at least one optical sensor at a plurality of predetermined angles of relative rotation between the sensor input member and the sensor output member.

15. The torque sensor of claim 14, wherein the torsionally resilient coupling member includes a torsion spring that is formed of wire.

16. A power tool comprising:

a tool portion having a motor and a transmission; and

a torque sensor that includes a rotatable sensor input member that is coupled for rotation with an output member of the transmission, a rotatable sensor output member, a torsionally resilient coupling member that couples the sensor input member to the sensor output member, and an optical sensor system that employs light to correlate relative rotation between the sensor input member and the sensor output member to a magnitude of a torque that is transmitted through the torque sensor.

17. The power tool of claim 16, wherein the torque sensor further comprises a controller that controls the motor in response to the magnitude of the torque that is transmitted through the torque sensor.

18. The power tool of claim 17, wherein the controller is configured to determine that a predetermined amount of torque is transmitted through the sensor portion and to responsively cause the motor to operate so that the sensor output member is rotated through a predetermined angle.

19. The power tool of claim 17, wherein the controller is configured to determine that a predetermined amount of torque is transmitted through the sensor portion and to responsively cause the motor to halt.

20. The power tool of claim 16, wherein the optical system includes a first encoder and a second encoder and wherein an amount of light that is transmitted through the first and second encoders varies in response to the magnitude of the torque that is transmitted through the torque sensor in a predetermined direction.

21. The power tool of claim 20, wherein the first and second encoders have a pair of windows that overlap one another to permit light to be transmitted through the first and second encoders.

22. The power tool of claim 21, wherein each of the windows has a pair of circumferentially-extending edges that diverge away from one another.

23. The power tool of claim 20, wherein an amount of light that is transmitted through the first and second encoders decreases as increasing torque is transmitted through the torque sensor in a direction opposite the predetermined direction.

24. The power tool of claim 23, wherein each of the windows has a pair of circumferentially-extending edges that diverge away from one another.

25. The power tool of claim 20, wherein an amount of light that is transmitted through the first and second encoders changes based an amount of relative rotation between the first and second encoders and wherein the change is non-linear.