Device for adjusting the measurement range of captors fitted with force balances particularly for pressure conveyors

Claim 2

In a force balance of the type comprising a balance-beam subjected to a displacement in accordance with a change in magnitude of a variable force to be measured and wherein said displacement is measured as a function of the force required to rebalance the beam, the improvement comprising a magnetically operated device for establishing the rebalancing force, said device including a winding comprising a plurality of coils having a predetermined turn ratio and which can be selectively connected in series, the number of coils in series circuit determining the force for rebalancing the balance-beam, switch means associated with each coil for selectively connecting the same into said series circuit, a power supply for feeding said series connected coils, circuit means including an amplifier for connecting the power supply to the series connected coils and means for controlling the amplification factor in proportion to the displacement of said balance-beam.

Claim 3

In a force balance as claimed in claim 1 wherein each of said switch means is connected across the end terminals of the appertaining coil.

Claim 4

In a force balance as claimed in claim 1 wherein the number of turns of the coils are chosen according to a binary ratio and further comprising a variable resistor connected in parallel to one of said coils whereby the force exerted by said one coil may be adjusted to a value between zero and the maximum force exertable thereby.

Claim 5

In a force balance as claimed in claim 1 wherein the coils may be selectively coupled in series and wherein said switches short-circuit said coils when closed and further comprising a variable resistor connected in parallel to one of said coils for adjusting the force exerted by said one coil between zero and the maximum force exertable thereby.

Claim 6

In a force balance as claimed in claim 1 wherein sAid coils are associated with the balance beam and the circuit means including an amplifier also includes a detector for sensing the position of the balance beam.

Claim 7

A force balance for determining fluid pressure differentials by a servo-rebalance system comprising a casing having opposed fluid ports therein, two distortable spaced parallel diaphragms mounted in said casing between said fluid ports, a fixed partition between said disphragms provided with a port therethrough, a bellows element mounted on said partition and surrounding said port on one side thereof, a magnetically operated device mounted on the same side of the partition as said bellows for establishing a rebalancing force, a balance-beam pivotally mounted adjacent said bellows and said magnetic device, one arm of said balance-beam being connected to said bellows to actuate same when said beam is pivoted, a plurality of coils connected to the other arm of the beam and having a predetermined turn ratio and which can be selectively connected in series, the number of coils in series circuit determining the force for rebalancing the balance-beam switch means associated with each coil for selectively connecting the same into said series circuit, a power supply connected to an amplifier for feeding said series connected coils, the space between said spaced diaphragms in which said balance-beam, said magnetic device, said plurality of coils and said bellows are disposed being filled with an incompressible liquid, whereby variations in the pressure of the fluid entering one of said fluid ports will distort said spaced diaphragms and thus actuate said balance-beam, and magnetic detector means responsive to movement of said balance beam for controlling the amplification factor of said amplifier and accordingly the current to at least one of said coils to restore the balance-beam to a null position and means for measuring the amount of current required.

Claim 8

A force balance for determining fluid pressure differentials by a servo-rebalance system comprising a casing having opposed fluid ports therein, two distortable spaced parallel diaphragms mounted in said casing between said fluid ports, a fixed partition between said disphragms provided with a port therethrough, a bellows element mounted on said partition and surrounding said port on one side thereof, a magnetically operated device mounted on the same side of the partition as said bellows for establishing a rebalancing force, a balance-beam pivotally mounted adjacent said bellows and said magnetic device, one arm of said balance-beam being connected to said bellows to actuate same when said beam is pivoted, a plurality of coils connected to the other arm of the beam and having a predetermined turn ratio and which can be selectively connected in series, the number of coils in series circuit determining the force for rebalancing the balance-beam switch means associated with each coil for selectively connecting the same into said series circuit, a power supply connected to an amplifier for feeding said series connected coils, the space between said spaced diaphragms in which said balance-beam, said magnetic device, said plurality of coils and said bellows are disposed being filled with an incompressible liquid, whereby variations in the pressure of the fluid entering one of said fluid ports will distort said spaced diaphragms and thus actuate said balance-beam, and magnetic detector means responsive to movement of said balance beam for controlling the amplification factor of said amplifier and accordingly the current to at least one of said coils to restore the balance-beam to a null position and means for measuring the amount of current required.