Mass and force meter

• US 4,075,887 A
• Filed: 12/22/1975
• Issued: 02/28/1978
• Est. Priority Date: 01/23/1975
• Status: Expired due to Term

• Current Assignee: K-Tron Patent AG (Hillenbrand Incorporated)
• Original Assignee: Wirth Gallo & Company
• Inventors: Gallo, Mario
• Primary Examiner(s): Ciarlante, Anthony V.
• Application Number:
  US05/643,326
• Time in Patent Office: 799 Days
• Field of Search: 73/141 R, 73/141 A, 73/DIG. 1, 73/517 AV, 177/210 R, 177/210 FP
• US Class Current: 73/862.59
• CPC Class Codes: G01G 3/16 measuring variations of frequency of oscillations of the body
• CPC Class Codes: G01L 1/10 by measuring variations of frequency of stressed vibrating elements, e.g. of stressed strings using resistance strain gauges G01L1/22
• CPC Class Codes: Y10S 73/01 Vibration

Abstract

A force and mass meter using two transversally vibrating preloaded strings as the force sensitive members. The two strings are placed in a transverse magnetic field and are caused to vibrate by means of an exciting current flowing across them which is delivered by one exciter each. The exciters consist of a metering bridge, and an operational amplifier deriving the exciting current from the error signal measured across the bridge. Mutual interference of the two exciters is drastically reduced, when the point of common potential of the two exciters is connected with at least one conductor to each of the exciters.

Claims

1. A mass and force meter comprising a frame, a digital evaluation and display device, two pre-tensioned electrically conductive strings, each having one end thereof fixed electrically insulated to said frame, a force distributor, the other end of said strings being connected electrically to said force distributor, an exciter comprising electrical circuits for each string controlling an alternative current, two electric conductors, one in each of said circuits being electrically connected to said force distributor, a magnetic field extending over a part of the length of said strings, said alternative current exciting said strings to transversal vibrations, first and second transmission elements for transmitting to said strings a pre-tensioning force and a force proportional to the mass or force to be measured respectively, an electrically insulating element at each end of said transmission elements, said insulating elements being connected to said force distributor, which is thereby electrically insulated from said frame, the other ends of said transmission elements being operatively connected to receive their respective forces, means for applying to the evaluation and display device resultant frequency variations caused by the variations of tension of said strings due to the application of the force proportional to the mass or force to be measured.

2. A mass and force meter comprising a frame, a digital evaluation and display device, two pre-tensioned electrically conductive strings, each having one end thereof fixed electrically insulated to said frame, a force distributor, the other end of said strings being connected electrically to said force distributor, an exciter comprising electrical circuits for each string controlling an alternative current, two electric conductors, one in each of said circuits being electrically connected to said force distributor, each of said electric conductors closing one of said electrical circuits, a magnetic field extending over a part of the length of said strings, said alternative current exciting said strings to transversal vibrations, first and second transmission elements for transmitting to said strings a pre-tensioned force and a force proportional to the mass for force to be measured respectively, an electrically insulating element at each end of said transmission elements, said insulating elements being connected to said force distributor, which is thereby electrically insulated from said frame, the other ends of said transmission elements being operatively connected to receive their respective forces, means for applying to the evaluation and display device resultant frequency variations caused by the variations of tension of said strings due to the application of the force proportional to the mass or force to be measured.

3. A mass and force meter comprising a frame, a digital evaluation and display device, two pre-tensioned electrically conductive strings, each having one end thereof fixed electrically insulated to said frame, a force distributor, the other end of said strings being connected electrically to said force distributor, an exciter comprising electrical circuits for each string controlling an alternative current, three electric conductors in said circuits being electrically connected to said force distributor, one of said electric conductors closing said circuits of both said exciters, each of the other two of said three electrical conductors closing a respective circuit of each of said electrical circuits, a magnetic field extending over a part of the length of said strings, said alternative current exciting said strings to transversal vibrations, first and second transmission elements for transmitting to said strings a pre-tensioning force and a force proportional to the mass or force to be measured respectively, an electrically insulating element at each end of said transmission elements, said insulating elements being connected to said force distributor, which is thereby electrically insulated from said frame, the other ends of said transmission elements being operatively connected to receive their respective forces, means for applying to the evaluation and display device resultant frequency variations caused by the variations of tension of said strings due to the application of the force proportional to the mass or force to be measured.