Strain gauge system

• US 3,899,924 A
• Filed: 06/07/1973
• Issued: 08/19/1975
• Est. Priority Date: 06/07/1973
• Status: Expired due to Term

• Current Assignee: Richard Edward Klein
• Original Assignee: Richard Edward Klein
• Inventors: Klein, Richard Edward
• Primary Examiner(s): Myracle, Jerry W.
• Assistant Examiner(s): Kreitman, Stephen A.
• Application Number:
  US05/367,828
• Time in Patent Office: 803 Days
• Field of Search: 73/88.5R,88R,141A,141R 177/136,210,211 323/75C,75A,79 324/71R
• US Class Current: 73/862.628
• CPC Class Codes: G01G 3/1402 Special supports with preselected places to mount the resistance strain gauges; Mounting of supports

Abstract

A strain gauge system incorporating a plurality of pairs of strain gauges, each of which is mounted on an axle or the like, said strain gauges being connected in a plurality of bridge circuits, each having an independent power supply, with the bridge circuits being connected in series to produce an output voltage which is proportional to the total load. A manually operable voltage source is connected with the output of the bridge circuits, and an operational amplifier is connected with the voltage source to sense when the output voltage of the bridge circuit equals the manually selected voltage. An output signal is produced selectively when a null condition is reached or when a condition corresponding to a predetermined load is approached from either direction.

Claims

1. A strain gauge load measuring system comprising a pair of strain gauges mounted on a load-supporting member, each of said strain gauges being located at a different predetermined distance from a supported end of said member, bridge circuit means interconnected with said strain gauges for deriving a signal having an amplitude dependent upon an actual load supported by said member, manually settable voltage divider means for setting a first reference signal to represent a first reference load, detector means connected with said bridge circuit means and with said voltage divider means for producing a signal indicating a net difference between said actual load signal and said first reference signal, means for producing a second manually adjustable reference level to represent a partial load, and comparator means for comparing said net difference signal and said second reference level and operative to produce a binary signal indicating the polarity of said net difference signal relative to said second reference level, whereby said bInary signal is in a first binary state when said net difference signal is one one side of said second reference level and in a second binary state when said net difference signal is on the other side of said second reference level.

2. A strain gauge load measuring system as defined in claim 1 and further comprising manual selectively operable sign-controlling means connected with said second reference level means for selectively assigning a positive and negative sign to said second reference level to characterize said partial load selectively as an increment and decrement of load relative to said first reference load, and further comprising first switch means for selectively rendering said comparator means responsive to conditions in which said net difference signals has a positive or a negative polarity relative to said second reference level.

3. A strain gauge load measuring system as defined in claim 2 and wherein said sign-controlling means includes second switch means arranged for simultaneous operation with said first switch means.

4. A strain gauge load measuring system as defined in claim 1 and further comprising indicating means connected with said detector means for indicating when said net difference signal is zero, whereby said indicating means indicates when said actual load is equal to said first reference load set in said voltage divider means.

5. A strain gauge load measuring system as defined in claim 1 and further comprising an additional pair of strain guages mounted on an additional load supporting member, and wherein said bridge circuit has four legs composed of the two pairs of said strain gauges, whereby each of said bridge circuits produces an output voltage proportional to the total load supported by the two load supporting members.

6. A strain gauge load measuring system as defined in claim 5 and including additional ones of said load supporting members and said bridge circuits, and means for connecting the output voltages produced by each of said bridge circuits in series to produce a composite total output voltage corresponding to the load supported by all of said load supporting members.