Leverless scale sensor

• US 4,143,727 A
• Filed: 03/30/1977
• Issued: 03/13/1979
• Est. Priority Date: 03/30/1977
• Status: Expired due to Term

• Current Assignee: Revere Transducers, Inc. (Vishay Intertechnology Incorporated)
• Original Assignee: Revere Corporation of America
• Inventors: Jacobson, Walter E.
• Primary Examiner(s): Miller, Jr., George H.
• Application Number:
  US05/782,714
• Time in Patent Office: 713 Days
• Field of Search: 177/211, 177/229, 177/255, 177/DIG. 3, 73/141 A
• US Class Current: 177/211
• CPC Class Codes: G01G 3/1404 combined with means to connect the strain gauges on electrical bridges
• CPC Class Codes: G01G 3/1412 the supports being parallelogram shaped

Abstract

This weighing scale has a platform, a load cell supporting the platform and a base supporting the load cell. The load cell utilizes electrical strain gage elements, which are connected in an electrical circuit controlling an indicator. The scale is constructed to be unaffected by the eccentricity of the load on the platform. The scale is particularly suited for use in retail or other establishments, where loads are placed on the platform casually and rapidly, so that eccentric loading is common. The load cell comprises an integral block of material divided by four transversely bored holes and two horizontal slots into two relatively rigid vertical members and three relatively flexible horizontal members connecting the vertical members. The platform is supported on one of the vertical members. The base is connected to the other vertical member. The upper and lower horizontal members transfer all bending moments due to eccentric loads from one vertical member to the other. The middle horizontal member is constructed so that it is stressed substantially only by the vertical component of the load. The strain gage elements are on this middle horizontal member and thus measure only the vertical load.

Claims

1. A load cell for converting variations in a force into variations in a force into variations in an electrical condition, comprising:

a. a pair of spaced, relatively rigid, parallel members extending in the direction of a force to be measured;

b. a pair of spaced, relatively flexible, parallel members extending between the relatively rigid members at right angles thereto and connected only thereto;

c. a fifth member extending between the relatively rigid members at right angles thereto and connected only thereto, said fifth member being located between and spaced from said flexible members and comprising;

1. two flexible elements, respectively fixed at one end to respective ones of said pair of relatively rigid members and having their opposite ends extending therefrom toward the other of said pair of relatively rigid members, said opposite ends being spaced and aligned in said direction; and

2. a flexure element connected between said opposite ends of said two flexible elements and extending in said direction, said flexure element being stressed longitudinally by said force and having four semicylindrical notches, one on each of its side faces adjacent each end thereof, said notches making said element laterally flexible in response to forces perpendicular to said force to be measured so that substantially only a force parallel to said force to be measured is transmitted through said fifth member; and

d. electrical strain responsive means on at least one of the flexible elements for converting strain variations therein to variations in an electrical condition which measures said force and is unaffected by moments due to eccentric application of said force to one of said rigid members.

2. A load cell as in claim 1, including transversely extending semicylindrical notches on the opposite recessed faces of the flexure element at the middle thereof.

3. A load cell as in claim 1, including:

a. a pair of aligned recesses in opposite faces of a narrow neck of said one flexible element, leaving a thin web of material between said aligned recesses;

b. a pair of holes having their centers aligned along a line parallel to the force being measured and extending through said web and leaving a narrow bridging portion thereof; and

c. said strain responsive means includes strain gage elements located on said narrow bridging portion of the web.