Dynamometric cell

• US 20060053898A1
• Filed: 09/19/2005
• Published: 03/16/2006
• Est. Priority Date: 03/21/2003
• Status: Active Grant

• Current Assignee: Bag Bizerba Automotive GmbH (Bizerba SE & Co. KG)
• Original Assignee: Bizerba GmbH & Company KG
• Inventors: Wurster, Klaus, Selig, Klaus Peter
• Granted Patent: US 7,380,475 B2
• Time in Patent Office: Days
• US Class Current: 73/818
• CPC Class Codes: B60R 21/01516 using force or pressure sensing means
• CPC Class Codes: G01G 19/4142 for controlling activation of safety devices, e.g. airbag systems electrical circuits for triggering safety arrangements in case of vehicle accidents B60R21/015

Abstract

A dynamometric cell having an elastically deformable force transducer for receiving a weight force and a sensor arrangement for detecting the deformation of the force transducer and its conversion into an electric weight signal is disclosed, wherein the force transducer is connected to a mounting member at its first end and supports a force introduction member at its second end, such that it allows a more exact determination of weight force even when it is incorporated into narrow spaces and wherein the force transducer is designed as a hollow bar with two attenuation zones spaced in longitudinal direction of the bar.

Claims

1. A dynamometric cell with an elastically deformable force transducer for receiving a weight force and a sensor arrangement for detecting the deformation of the force transducer and its conversion into an electric weight signal, wherein the force transducer is connected to a mounting member at a first end and supports a force introduction member at its second end, wherein the force transducer is designed as a hollow bar with two attenuation zones spaced in longitudinal direction of the bar.

2. The dynamometric cell as defined in claim 1, wherein the attenuation zones are designed such that the force transducer is able to carry out elastic deformation movements in more than one plane when acted upon by weight forces to be determined.

3. The dynamometric cell as defined in claim 1, wherein the attenuation zones comprise a section of the hollow bar having a reduced wall thickness.

4. The dynamometric cell as defined in claim 1, wherein the attenuation zones are formed only partially in circumferential direction of the hollow bar in circular segments located radially opposite one another.

5. The dynamometric cell as defined in claim 1, wherein the hollow bar has a polygonal cross section.

6. The dynamometric cell as defined in claim 1, wherein the hollow bar has a circular or oval cross section.

7. The dynamometric cell as defined in claim 1, wherein the hollow bar has a passage in the form of a transverse bore in the area centrally between the attenuation zones.

8. The dynamometric cell as defined in claim 1, wherein the hollow bar has passages in two segments located radially opposite one another, said passages extending at least from the one attenuation zone as far as the other attenuation zone.

9. The dynamometric cell as defined in claim 8, wherein the passages extend essentially as far as the second end of the hollow bar supporting the force introduction member.

10. The dynamometric cell as defined in claim 1, wherein the force introduction member is of a pot-shaped design and surrounds the force transducer with its open end.

11. The dynamometric cell as defined in claim 10, wherein the force introduction member extends essentially over the entire length of the force transducer so that the open end of the force introduction member is arranged so as to be adjacent to the mounting member.

12. The dynamometric cell as defined in claim 10, wherein the force introduction member is essentially free from any apertures.

13. The dynamometric cell as defined in claim 10, wherein the force introduction member and the mounting member have fixing sections defining a force introduction and a force deflection in adjacent planes.

14. The dynamometric cell as defined in claim 1, wherein the force introduction member is of a hollow cylindrical design and is connected at one end to the second end of the force transducer.

15. The dynamometric cell as defined in claim 14, wherein the force introduction member comprises an external thread section at its end connected to the force transducer.

16. The dynamometric cell as defined in claim 14, wherein the force introduction member essentially encloses the force transducer over its entire length.

17. The dynamometric cell as defined in claim 16, wherein the force introduction member is mounted with its other end on the mounting member so as to be movable.

18. The dynamometric cell as defined in claim 17, wherein the mounting member has an annular receiving means for the other end of the force introduction member.

19. The dynamometric cell as defined in claim 17, wherein the force introduction member is held on the mounting member with a stop limiting the movement of the force introduction member.

20. The dynamometric cell as defined in claim 1, wherein a retaining element is arranged on the mounting member coaxially to the hollow bar, said retaining element extending into said bar and serving to hold the sensor arrangement or a part thereof.

21. The dynamometric cell as defined in claim 20, wherein the retaining element comprises a recess for guiding electric signal cables of the sensor arrangement.

22. The dynamometric cell as defined in claim 1, wherein the dynamometric cell comprises an integrated, mechanical overload protection.

23. The dynamometric cell as defined in claim 22, wherein the mechanical overload protection comprises a stop limiting the elastic deformation movement of the force transducer.

24. The dynamometric cell as defined in claim 23, wherein the stop is formed on the retaining element and limits a deformation movement of the force transducer itself.

25. The dynamometric cell as defined in claim 23, wherein the stop is formed on the mounting member and on the force introduction member and limits the deformation movement of the force transducer indirectly.

26. The dynamometric cell as defined in claim 23, wherein the stop is formed on the force introduction member and on the force transducer.

27. The dynamometric cell as defined in claim 13, wherein the retaining element comprises a recess for accommodating a sensor element.

28. The dynamometric cell as defined in claim 27, wherein the recess has a guide element for determining the geometric alignment of the sensor element.

29. The dynamometric cell as defined in claim 1, wherein the sensor arrangement comprises one or more wire strain gauges.

30. The dynamometric cell as defined in claim 1, wherein the sensor arrangement comprises a sensor arrangement for a contact-free distance measurement.

31. The dynamometric cell as defined in claim 1, wherein the sensor arrangement is a sensor arrangement operating inductively.

32. The dynamometric cell as defined in claim 31, wherein the sensor arrangement comprises a Hall sensor and a magnet.

33. The dynamometric cell as defined in claim 32, wherein the magnet is a permanent magnet.

34. The dynamometric cell as defined in claim 32, wherein the magnet is arranged on the force introduction member and the Hall sensor on the retaining element.

35. The dynamometric cell as defined in claim 32, wherein the magnet is arranged on the retaining element and the Hall sensor on the force introduction member.

36. The dynamometric cell as defined in claim 32, wherein the Hall sensor and the magnet of the sensor arrangement are designed and arranged such that in the no-load state of the dynamometric cell the Hall sensor generates an electric signal with a value smaller than a third of the value of the maximum effective signal.

37. The dynamometric cell as defined in claim 36, wherein the magnet is designed to act as a monopole in relation to the Hall sensor and wherein the Hall sensor comprises an even number of sensor elements arranged in the form of a two-dimensional matrix located opposite the monopole, wherein two of the sensor elements form a respective part of an electronic differential circuit.

38. The dynamometric cell as defined in claim 36, wherein the magnet is designed to act as a dipole in relation to the Hall sensor and wherein the Hall sensor comprises one or more sensor elements, the signals of said sensor elements being detectable separately.

39. The dynamometric cell as defined in claim 1, wherein the sensor arrangement comprises an optical sensor element.

40. The dynamometric cell as defined in claim 39, wherein the sensor comprises a light source and a slot diaphragm, and a differential photodiode, wherein the light source and the slot diaphragm are held together on the force transducer and the differential photodiode is arranged on the stationary mounting member of the dynamometric cell.

41. The dynamometric cell as defined in claim 39, wherein the sensor comprises a light source and a slot diaphragm, and a differential photodiode, wherein the light source and the slot diaphragm are arranged together on the stationary mounting member of the dynamometric cell and the differential photodiode is held on the force transducer.