Electromagnetically compensated balance or dynamometer

• US 4,004,458 A
• Filed: 03/05/1976
• Issued: 01/25/1977
• Est. Priority Date: 03/13/1975
• Status: Expired due to Term

• Current Assignee: Sartorius-Werke GmbH
• Original Assignee: Sartorius-Werke GmbH
• Inventors: Berg, Christoph, Knothe, Erich, Melcher, Franz Josef
• Primary Examiner(s): Myracle, Jerry W.
• Application Number:
  US05/664,416
• Time in Patent Office: 326 Days
• Field of Search: 73/141 R, 310/14, 310/23, 310/30, 310/13
• US Class Current: 73/862.61
• CPC Class Codes: G01G 7/04 with means for regulating the current to solenoids
• CPC Class Codes: G01L 1/086 using electrostatic or electromagnetic counterbalancing forces

Abstract

A balance or dynamometer which comprises a coil in the work gap of an eleomagnet having a core provided with discrete groups of turns, the number of ampere turns in the groups of turns corresponding to the sequence or code values of a preselector code, the coil and electromagnet being disturbed from a predetermined position relative to each other under the influence of a force; such disturbance being recorded by a position indicator connected to the input of a forward/backward counter; means for arranging that the number registered in the counter at any one time connects an associated number of groups of turns to a constant current source connected to the coil; the coil and electromagnet returning to said predetermined position when the counter has connected an appropriate number of groups of turns to the constant current source to compensate for the disturbing force.

Claims

1. An electromagnetically compensated balance or dynamometer which comprises a coil disposed in the work gap of a magnet, said magnet being an electromagnet having a soft magnet core provided with discrete groups of turns, the number of ampere turns in the groups of turns corresponding to the sequence of code values of a preselected code, either said coil or magnet being movable and being deflected out of a predetermined equilibrium position relative to the unmovable one of the magnet or coil under the influence of a force, a position indicator, logic means including a counter, the input of the counter being connected to the position indicator and the output of the counter being connectable to selected ones of the groups of turns to provide a concordance between the count held in the counter and the number of ampere turns in the selected groups of turns, and a constant current source;

the position indicator;

in the presence of a deflection, controlling the counter as a function of the direction of deflection, and the logic means connecting the output of the constant current source to the coil and to the particular groups of turns associated with the count held in the counter whereby the deflection is compensated and the movable one of the magnet or coil is returned to its predetermined equilibrium position and the final count held in the counter is proportional to the magnitude of the force.

2. A balance or dynamometer according to claim 1, wherein, in the presence of a deflection, the position indicator connects the output of a cyclic oscillator, as a function of the direction of deflection, to the forward or backward input of a coded forward/backward counter, the outputs of which counter are associated with the digits of a specific code, and the logic means comprises switch means wherein switches are respectively connected to individual groups of turns, each switch being controlled by an associated one of the coded outputs of the forward/backward counter.

3. A balance or dynamometer according to claim 2, wherein the switches are two-position selector switches which alternatively connect their associated groups of turns to the constant current source or by-pass them as a function of the count in the counter.

4. A balance or dynamometer according to claim 2, wherein the position indicator exhibits two directional outputs, each of which is amplified and then connected to separate AND-gates, a second input of each AND gate being connected to the output of the cyclic oscillator, and the output of each AND gate being connected to the forward or backward input of the forward/backward counter.

5. A balance or dynamometer according to claim 1, wherein the selected code for the groups of turns is binary code (2ⁿ), BCD code (2⁰, 2¹, 2², 2³ , 10 ×

2⁰, 10 ×

2¹, 10 ×

2², 10 ×

2³, 10² ×

0 . . . ), or ternary code (3ⁿ).

6. A balance or dynamometer according to claim 5, wherein the code of the counter outputs corresponds to the code of the groups of turns.

7. A balance or dynamometer according to claim 5, wherein between the counter and the groups of turns is provided a code converter which adapts the code of the counter ouputs of the code of the groups of turns.

8. A balance of dynamometer according to claim 1, wherein the logic means switches over in large steps between the higher ranking coded groups of turns in the case of a deflection exceeding a preselected value, and in small steps for a deflection not exceeding the preselected value.

9. A balance or dynamometer according to claim 1, wherein the output of the constant current source is controlled by a reference standard.

10. A balance or dynamometer according to claim 1, wherein the groups of turns of the lowest ranking decades exhibit a number of turns higher by a preselected factor and a fixed fraction of the constant current equal to the reciprocal of this factor is fed to them.

11. In an electromagnetically compensated balance or dynamometer having a coil disposed in the work gap of a magnet, either said coil or magnet being movable and being deflected out of a predetermined equilibrium position relative to the unmovable one of the magnet or coil under the influence of a force, and a position indicator which, in the presence of a deflection, controls a counter as a function of the direction of deflection, the output signals of said counter returning the coil or magnet to said predetermined equilibrium position, the improvement which comprises providing a constant current source, a cyclic oscillator, and a plurality of two position selector switches, said counter being a forward/backward counter and said magnet being an electromagnet having a soft core provided with discrete groups of turns, the number of ampere turns corresponding to the sequence of code values of a preselected code;

the position indicator, in the presence of a deflection, connecting the output of the cyclic oscillator, as a function of the direction of deflection, to the forward or backward input of the coded forward/backward counter, the ouputs of which counter are associated with the digits of a specific code, the two position selector switches being respectively connected to individual groups of turns, each switch being controlled by an associated one of the coded outputs of the forward/backward counter and which connect their associated groups of turns to the constant current source or by-pass them as a function of the count in the counter, whereby the deflection is compensated and the moveable one of the magnet or coil is returned to its predetermined equilibrium position and the final count held in the counter is proportional to the magnitude of the force.