LOAD CELL

• US 20080022784A1
• Filed: 08/24/2007
• Published: 01/31/2008
• Est. Priority Date: 03/03/2005
• Status: Active Grant

• Current Assignee: Bag Bizerba Automotive GmbH (Bizerba SE & Co. KG)
• Original Assignee: Bag Bizerba Automotive GmbH (Bizerba SE & Co. KG)
• Inventors: Baltinger, Joerg, Wehinger, Rolf-Dieter, Plocher, Thomas, Metzger, Frank
• Granted Patent: US 7,444,889 B2
• Time in Patent Office: Days
• US Class Current: 73/862.621
• CPC Class Codes: G01G 3/12 wherein the weighing element is in the form of a solid body stressed by pressure or tension during weighing
• CPC Class Codes: G01L 1/04 by measuring elastic deformation of gauges, e.g. of springs
• CPC Class Codes: G01L 1/14 by measuring variations in capacitance or inductance of electrical elements, e.g. by measuring variations of frequency of electrical oscillators

Abstract

To provide a load cell, having a force transducer for recording tensile and compressive forces that are to be determined, which can be produced more economically and, in particular, can also be handled more easily during the adjustment of the sensor arrangement than hitherto, the force transducer comprising a flectionally elastic element and a force introduction part acting on the flectionally elastic element, having a sensor arrangement for detecting a deformation of the flectionally elastic element and the transformation thereof into an electric weighing signal, and having a housing receiving the force transducer and the sensor arrangement, with a flectionally rigid wall part, on which the flectionally elastic element of the force transducer is held, it is proposed that the sensor arrangement be arranged on a separate carrier, which is held on the flectionally rigid wall part and/or a flectionally rigid base part region of the housing

Claims

1. A load cell, comprising:

a force transducer for recording tensile and compressive forces to be determined;

wherein the force transducer comprises a flectionally elastic element and a force introduction part acting on the flectionally elastic element;

a sensor arrangement for detecting a deformation of the flectionally elastic element and the transformation thereof into an electric weighing signal; and

a housing receiving the force transducer and the sensor arrangement with a flectionally rigid wall part, on which the flectionally elastic element of the force transducer is held;

wherein the sensor arrangement is arranged on a separate carrier, which is held on at least one of the flectionally rigid wall part and a flectionally rigid base part region of the housing.

2. The load cell according to claim 1, wherein the carrier is held and supported exclusively on the flectionally rigid wall part of the housing.

3. The load cell according to claim 1, wherein the sensor arrangement comprises a transmitter element and a sensor element, a first of these two elements being held stationarily on the carrier and the second of these elements being held movably on the carrier with respect to the first element.

4. The load cell according to claim 3, wherein the second element is held on a spring part of the carrier.

5. The load cell according to claim 3, wherein the second element is arranged in a neutral point of the Sectionally elastic element in the unloaded state of the force transducer.

6. The load cell according to claim 1, wherein the sensor arrangement is a sensor arrangement for contact-free path measurement.

7. The load cell according to claim 6, wherein the sensor arrangement is a Hall sensor arrangement.

8. The load cell according to claim 6, wherein the sensor arrangement is an optical sensor arrangement.

9. The load cell according to claim 3, wherein at least one of the transmitter element and the sensor element is mechanically held on the carrier.

10. The load cell according to claim 1, wherein the flectionally elastic element comprises a flectionally elastic membrane, which is held on the flectionally rigid wall part of the housing by its edge region.

11. The load cell according to claim 10, wherein the flectionally elastic membrane is a metal membrane.

12. The load cell according to claim 10, wherein the flectionally elastic membrane comprises a central recess.

13. The load cell according to claim 12, wherein the membrane is configured as an annular disc.

14. The load cell according to claim 1, wherein the force introduction part and the Sectionally elastic element are configured in one piece.

15. The load cell according to claim 1, wherein the force introduction part is displaceably arranged coaxially in a through-opening of the housing.

16. The load cell according to claim 1, wherein the force introduction part has a foot part acting on the flectionally elastic element and a contact element which can be adjusted relative to the foot part and is arranged in mechanical contact with a component of the sensor arrangement held movably on the carrier.

17. The load cell according to claim 16, wherein the mechanical contact of the contact element with the movable component is a substantially point-wise contact.

18. The load cell according to claim 16, wherein the contact element has a rounded tip, by means of which the mechanical contact with the movable component of the sensor arrangement can be produced.

19. The load cell according to claim 18, wherein the rounded tip of the contact element is in sliding mechanical contact with the movably held component of the sensor arrangement.

20. The load cell according to claim 16, wherein the housing has a through-opening and the foot part of the force introduction part has a larger radial dimension than the through-opening of the housing.

21. The load cell according to claim 15, wherein the force introduction part projects out of the housing through the through-opening.

22. The load cell according to claim 1, wherein the load cell has stop means, which limit the movement of the force introduction part upon the action of force.

23. The load cell according to claim 22, wherein the stop means limit the movement of the force introduction part upon the action of tensile forces and also compressive forces.

24. The load cell according to claim 23, wherein the stop means comprise a first element, which is supported on the outside of the housing.

25. The load cell according to claim 24, wherein the first element of the stop means has a receiver for an elastomer element on its side facing the outside of the housing.

26. The load cell according to claim 24, wherein the first element is arranged on region of the force introduction part arranged outside the housing.

27. The load cell according to claim 23, wherein the stop means comprise a second element, which is supported on the inside of the housing.

28. The load cell according to claim 27, wherein the second element is configured as a foot part of the force introduction part.

29. The load cell according to claim 1, wherein the housing substantially surrounds the force transducer and the sensor arrangement on all sides.

30. The load cell according to claim 1, wherein the housing comprises a cover element a base element and a flectionally rigid side wall connecting the cover element to the base element.

31. The load cell according to claim 30, wherein the housing is multi-part.

32. The load cell according to claim 31, wherein the housing is formed from a cover part and a base part.

33. The load cell according to claim 31, wherein the parts of the housing are welded to one another.

34. The load cell according to claim 30, wherein the housing has a through-opening and the cover element surrounds the through-opening of the housing to receive and guide through the force introduction part.

35. The load cell according to claim 1, wherein the housing comprises a through-opening for at least one of electrical supply lines and signal lines.

36. The load cell according to claim 30, wherein the base element has one or more fastening elements.

37. The load cell according to claim 36, wherein a threaded part is configured on the base element.

38. The load cell according to claim 37, wherein the threaded part is configured in one piece with the base element.

39. The load cell according to claim 32, wherein the flectionally elastic element is held between two housing parts with a force fit.

40. The load cell according to claim 1, wherein the Sectionally element is connected to the housing by means of a weld point.

41. The load cell according to claim 1, wherein the carrier is connected to the housing with a material connection.

42. The load cell according to claim 11, wherein the housing has a through-opening that is configured as a guide for the force introduction part.

43. The load cell according to claim 42, wherein the through-opening of the housing guides the force introduction part so as to be secured against tilting moments.

44. The load cell according to claim 11, wherein the housing has a through-opening, and a gap, the gap having a width of about 0.1 mm to about 0.5 mm, present between the force introduction part and the through-opening.

45. The load cell according to claim 3, wherein the transmitter element and the sensor element are arranged non-centrally on the carrier.

46. The load cell according to claim 45, wherein the transmitter element is arranged below the sensor element, the sensor element being movable in a space above the transmitter element.

47. The load cell according to claim 45, wherein the carrier has a recess, in which the sensor element is arranged.

48. The load cell according to claim 47, wherein the recess is formed on a spring part of the carrier.

49. The load cell according to claim 45, wherein the transmitter element and the sensor element are arranged transversely offset with respect to an axis of a contact element.

50. The load cell according to claim 1, wherein the carrier has a contact region, which is concave.

51. The load cell according to claim 50, wherein the contact region is arranged between spaced-apart spring webs.

52. The load cell according to claim 1, further comprising a spring part supported on the carrier wherein the spring part has spaced-apart spring webs, which webs include spaced-apart weakening zones.

53. The load cell according to claim 52, wherein corresponding weakening zones of different spring webs are located at the same height.

54. The load cell according to claim 1, wherein the carrier is held between two housing parts with a force fit.