Two-axis sensor body for a load transducer

• US 9,778,122 B2
• Filed: 08/01/2014
• Issued: 10/03/2017
• Est. Priority Date: 08/01/2013
• Status: Active Grant

• Current Assignee: MTS Systems Corporation (Illinois Tool Works Inc.)
• Original Assignee: MTS Systems Corporation (Illinois Tool Works Inc.)
• Inventors: Meyer, Richard A., Josephson, Robert L., Christopherson, Jason A., Osmundson, Todd Robert, LaMoore, Nicholas Devon, Rogotzke, Riley August
• Primary Examiner(s): Caputo, Lisa
• Assistant Examiner(s): Tran, Tran M
• Application Number:
  US14/449,849
• Publication Number:
  US 20150033875A1
• Time in Patent Office: 1,159 Days
• CPC Class Codes: G01L 1/2206 Special supports with preselected places to mount the resistance strain gauges; Mounting of supports
• CPC Class Codes: G01L 1/26 Auxiliary measures taken, or devices used, in connection with the measurement of force, e.g. for preventing influence of transverse components of force, for preventing overload
• CPC Class Codes: G01L 5/00 Apparatus for, or methods of, measuring force, work, mechanical power, or torque, specially adapted for specific purposes
• CPC Class Codes: G01L 5/162 of piezoresistors
• CPC Class Codes: G01L 5/168 using counterbalancing forces
• CPC Class Codes: G01M 9/02 Wind tunnels
• CPC Class Codes: G01M 9/062 Wind tunnel balances; Holding devices combined with measuring arrangements

Abstract

In one aspect, a transducer body includes a support having clevis halves. The sensor body includes a generally rigid peripheral member disposed about a spaced-apart central hub joined to each of the clevis halves. At least three flexure components couple the peripheral member to the hub. The flexure components are spaced-apart from each other at generally equal angle intervals about the hub; the sensor body further including a flexure assembly for some flexure components joining the flexure component to at least one of the hub and the peripheral member, the flexure assembly being compliant for forces in a radial direction from the hub to the peripheral member. Each flexure assembly is configured such that forces transferred concentrate strain at a midpoint along the length of each corresponding flexure component.

Claims

1. A transducer body, comprising:

a support comprising a pair of clevis halves; and

sensor body coupled to each of the clevis halves, wherein the sensor body is disposed between the clevis halves and configured to deflect with forces along two orthogonal axes, wherein the sensor body includes a peripheral member disposed about a spaced-apart central hub, the central hub being joined to each of the clevis halves with the peripheral member spaced apart from each clevis half, wherein at least three flexure components couple the peripheral member to the central hub, and wherein the flexure components are spaced-apart from each other at angular intervals about the central hub;

the sensor body further including a flexure assembly for each of said at least three flexure components joining its flexure component to at least one of the central hub and the peripheral member, each flexure assembly being compliant for forces in a radial direction from the central hub through the flexure component and to the peripheral member, wherein at least two flexure assemblies are configured such that forces transferred between the central hub and the peripheral member concentrate strain at a midpoint along a longitudinal length of each corresponding flexure component configured for strain measurement, and wherein the at least two flexure assemblies and the corresponding flexure component midpoint are collinear.

2. The transducer body of claim 1 wherein each flexure assembly is configured such that forces transferred between central hub and the peripheral member cause a first force at the connection of the flexure component to the central hub to be equal and opposite to a second force at the connection of the flexure component to the peripheral member, wherein the first and second force are tangential to the radial direction of each corresponding flexure component.

3. The transducer body of claim 1 wherein at least two flexure components are configured to concentrate strain in shear.

4. The transducer body of claim 1 wherein at least two flexure components are configured to concentrate strain in bending.

5. The transducer body of claim 1 wherein at least two flexure components are configured with a pair of beams.

6. The transducer body of claim 5 wherein the pair of beams of each flexure component of said at least two flexure components is formed by an aperture.

7. The transducer body of claim 1, and further comprising:

a biasing assembly connected between the support and the sensor body and configured to provide a bias force between the sensor body and the support.

8. The transducer body of claim 7 wherein the biasing assembly comprises a bias connector configured to operate in tension to provide the bias force.

9. The transducer body of claim 8 wherein the biasing assembly comprises a removable biasing actuator configured to be connected between the sensor body and the support.

10. The transducer body of claim 8 wherein the bias connector comprises an elongated strap having a width of the strap greater than a thickness of the strap.

11. The transducer body of claim 10 wherein the biasing assembly comprises a pair of straps provided on opposite portions of the transducer body that are symmetrical.

12. The transducer body of claim 11 wherein the biasing connector comprises a flexible member fixedly connected to one of the sensor body or the support.

13. The transducer body of claim 12 wherein each flexible member comprises a cantilevered beam with one of the biasing connectors connected to one of the flexible members.

14. The transducer body of claim 12 wherein the flexible member is integrally formed from a single unitary body of one of the sensor body or the support.

15. The transducer body of claim 14 wherein the flexible member is provided on the sensor body.

16. The transducer body of claim 14 wherein the flexible member is provided on the support.

17. The transducer body of claim 10 wherein the biasing assembly comprises a pair of biasing connectors wherein a biasing connector is provided each of opposite portions of the transducer body that are symmetrical.

18. The transducer body of claim 17 wherein a flexible member is provided on each clevis half and a bridging block connects the flexible members together, the bridging block being spaced apart from the sensor body.

19. The transducer body of claim 17 wherein the biasing assembly comprises flexible members, a flexible member being fixedly connected to one of the sensor body or the support.

20. The transducer body of claim 19 wherein the flexible members are integrally formed from a single unitary body of one of the sensor body or the support.

21. The transducer body of claim 1, and further comprising:

a lockup assembly configured to selectively inhibit movement of the sensor body relative to the clevis halves.

22. The transducer body of claim 21 wherein the lockup assembly is configured to inhibit movement of the peripheral member relative to the clevis halves.

23. The transducer body of claim 22 wherein the lockup assembly inhibits movement of the peripheral member by frictional contact.

24. The transducer body of claim 23 wherein the lockup assembly is configured to selectively move portions having engaging surfaces for frictional contact to contact opposed surfaces of the peripheral member, the engaging surfaces and the opposed surfaces being spaced apart from each other to allow forces to be transferred by the flexure components when the lockup assembly is not engaged.

25. The transducer body of claim 24 wherein the lockup assembly comprises a first plate member joined to a first clevis half and a second plate member joined to a second clevis half, wherein the engaging surfaces are disposed on the plate members.

26. The transducer body of claim 25 wherein a portion of each plate member is spaced apart from the associated clevis half.

27. The transducer body of claim 26 wherein when the engaging surfaces engage the opposed surfaces, the portion of each plate member frictionally engages the associated clevis half.

28. The transducer body of claim 27 and further comprising an actuator configured to selectively bring the engaging surfaces in contact with the opposed surfaces and also bring the portions of each plate member into contact with each associated clevis half.

29. The transducer body of claim 28 wherein major surfaces of the portions of the plate members engage major surfaces of the associated clevis halves.

30. The transducer body of claim 29 wherein the engaging surfaces are on the plate members, and wherein each plate member comprises a hinges and a link portion between the hinges, the link portion connecting portions of the plate members having the engaging surfaces with portions of the plate members having the major surfaces.

31. The transducer body of claim 30 wherein the actuator is operably mounted to the portions of the plate members having the engaging surfaces, and wherein the actuator includes a pull rod to selectively pull the pull rod so as to bring the engaging surfaces in contact with the opposed surfaces.

32. The transducer body of claim 31 wherein the pull rod extends through a bore opening to one of the opposed surfaces, the pull rod being spaced apart from inner surfaces of the bore at least when the actuator is not pulling on the pull rod to bring the engaging surfaces in contact with the opposed surfaces.

33. The sensor body of claim 1 and further comprising a strain sensor operably coupled to the midpoint of each flexure component.

34. A transducer body, comprising:

a support comprising a pair of clevis halves; and

a sensor body coupled to each of the clevis halves, wherein the sensor body is disposed between the clevis halves and configured to deflect with forces along two orthogonal axes, wherein the sensor body includes a peripheral member disposed about a spaced-apart central hub, the central hub being joined to each of the clevis halves with the peripheral member spaced apart from each clevis half, wherein at least three flexure components couple the peripheral member to the central hub, and wherein the flexure components are spaced-apart from each other at angular intervals about the central hub;

the sensor body further including a flexure assembly for each of said at least three flexure components joining its flexure component to at least one of the central hub and the peripheral member, the flexure assembly being compliant for forces in a radial direction from the central hub through the flexure component and to the peripheral member, wherein each of at least two flexure assemblies comprises a first connecting web orthogonal to its flexure component, and the first connecting web is disposed to be approximately in line with a midpoint along a longitudinal length of its corresponding flexure component, wherein forces transferred between the central hub and the peripheral member concentrate strain at the midpoint of each corresponding flexure component configured for strain measurement, and wherein the at least two flexure assemblies and the corresponding flexure component midpoint are collinear.

35. The sensor body of claim 34, wherein each of said at least two flexure assemblies comprises a second connecting web on a side of the corresponding flexure component opposite the corresponding first connecting web.

36. The sensor body of claim 34 and further comprising a strain sensor operably coupled to the midpoint of each flexure component.