Load cells and scales therefrom

• US 5,090,493 A
• Filed: 10/29/1990
• Issued: 02/25/1992
• Est. Priority Date: 10/29/1990
• Status: Expired due to Term

• Current Assignee: International Road Dynamics Incorporated (Quarterhill Inc. (f/k/a Wi-LAN Inc.))
• Original Assignee: International Road Dynamics Incorporated (Quarterhill Inc. (f/k/a Wi-LAN Inc.))
• Inventors: Taylor, Brian, Bergan, Terry
• Primary Examiner(s): MILLER JR, GEORGE
• Application Number:
  US07/604,475
• Time in Patent Office: 484 Days
• Field of Search: 73/862.65, 177/128, 177/134, 177/211, 177/229, 338/5
• US Class Current: 177/211
• CPC Class Codes: G01G 3/1408 the supports being of the column type, e.g. cylindric

Abstract

A novel load cell for use in novel wheel load scales and novel weigh-in-motion scales is provided herein. The load cell comprises a metal rod or bar, with a strain transducer secured to a flattened portion of each of the upper and lower faces of the metal bar. A signal wire has its terminal secured to an end face of each of such strain transducer, and a strain relief means is interposed between each such signal wire terminal and its associated strain transducer. When mounted within a closed bore which is parallel to the upper surface of a flat plate of elastic material, e.g., sheet metal, in a particularly-recited manner, an improved wheel load scale or weigh-in-motion scale is provided. This provides a light weight, low profile, scale which is isolated from external interference, which improves the accuracy of the scale.

Claims

1. A load cell comprising:

a metal rod or bar having upper and lower faces;

a strain transducer secured to a portion of each of the upper and lower faces of said metal bar;

a signal wire having its terminal secured to one end face of each said strain transducer; and

a strain relief means interposed between each said signal wire terminal and an associated said strain transducer.

2. The load cell of claim 1 wherein said strain transducers are situated on a reduced thickness portion of said metal rod or bar.

3. The load cell of claim 2 wherein each said signal wire is disposed within a respective groove in said reduced thickness portion of said metal rod or bar.

4. The load cell of claim 2 wherein said strain transducer comprises an electric resistance-type strain gauge.

5. The load cell of claim 4 wherein said electric resistance-type strain gauge is a very thin film of highly polarized polyvinylidene fluoride.

6. The load cell of claim 2 wherein said terminal between each said signal wire and an associated said strain transducer comprises a solder terminal.

7. The load cell of claim 2 wherein each said strain relief means comprises a strain relief bubble.

8. A flat plate wheel load indicator adapted for support at its lateral edges, said plate having its lateral edges slotted to form a plurality of laterally-extending webs;

a single cavity extending into each of said webs from said lateral edges; and

a load cell, as claimed in claim 1, removably slidably disposed within each said cavity, said strain transducers forming part of said load cell being unadhered to any wall of said cavity.

9. The load wheel scale as claimed in claim 8, wherein said cavities are each formed by closed bores.

10. The wheel load scale as claimed in claim 9, wherein said bores start from a lateral edge of said plate and extend transversely into said plate.

11. The wheel load scale as claimed in claim 8, including a depending foot to support said plate, the other areas of said plate being unsupported.

12. The wheel load scale as claimed in claim 8, wherein each longitudinal side of said plate is provided with two such webs.

13. The wheel load scale as claimed in claim 8, wherein said plate is made of steel or aluminum or of a high-strength light metal alloy.

14. A wheel load scale as claimed in claim 8, including a handle provided in each lateral edge of the plate.

15. A wheel load scale as claimed in claim 8, including a display panel mounted on a transverse edge of the plate.

16. A wheel load scale as claimed in claim 15, wherein said display panel is supplied with electrical power from a storage battery.

17. A wheel load scale as claimed in claim 16, wherein said storage battery may be charged through a charging connector.

18. A weigh-in-motion scale comprising:

a flat plate of elastic material having measuring properties, said plate being adapted to be supported at two opposed lateral edges and including pockets disposed in pairs and forming webs between them;

a closed cavity provided in each web extending in a direction substantially-parallel to the upper surface of said plate; and

a load cell, as claimed in claim 1, removably slidably disposed within each said cavity, said strain transducer forming part of said load cell being unadhered to any wall of said cavity.

19. The weigh-in-motion scale of claim 18, disposed in a rectangular frame, the interior thereof being provided with a peripheral frame having a plurality of scale frame bearing pads to support a like member of webs of said plate.

20. The weigh-in-motion scale as claimed in claim 18, wherein said cavities are formed by closed bores.

21. The weigh-in-motion scale as claimed in claim 20, wherein said pockets are spaced from a lateral edge of said plate, and wherein said bores start from a lateral edge of said plate and extend transversely into said plate.

22. The weigh-in-motion scale as claimed in claim 19, including a depending foot secured to each said bearing pads to support said webs, the other areas of said plate being unsupported.

23. The weigh-in-motion scale as claimed in claim 19, wherein each longitudinal side of said plate is provided with two such webs.

24. The weigh-in-motion scale as claimed in claim 18, wherein said plate is made of steel or aluminum or of a high-strength light metal alloy.