US 4,225,290 A · Pumping system

Abstract

An improved chromatographic pump control circuit for compensating for pulsation in pump flow over a wide range of flow-rates and pressures and for providing improved protection against pump pressure and motor torque fault conditions. The control circuit is coupled to a pump motor to provide motor speed-up during the repressurization portion of the pump cycle as a function of the set point pump flow rate. The circuit also includes a summing circuit for developing a repressurization signal based on the flow-rate and detected pressure. The signal is coupled to compensate for pulsation by controlling the duration of repressurization with respect to both pressure and the set point of the flow rate. The circuit is additionally coupled to sense pump pressure and motor torque to initiate alarm and pump shutdown during high and low pressure and motor over-torque fault conditions.

Claims26

Dependent claims

A circuit for compensating for pulsations in pump flow-rate by controlling pump motor speed during delivery, refill, and repressurization periods of a pump cycle comprising:

a first pump driven by a first motor;
means for providing at least one signal representing pump flow-rate;
first motor control means coupled to said motor and responsive to said flow-rate signal for driving the first motor at a speed proportional to said flow-rate signal during the delivery period of the pump cycle and at an increased speed during the refill and repressurization periods of the pump cycle;
and
interface control means coupled to said motor control means and responsive to said flow-rate signal for providing a repressurization signal causing the first motor control means to increase motor speed during repressurization for a time period proportional to the magnitude of the repressurization signal.

2 more elements

In a chromatographic system including a chromatographic means providing a stationary phase, a conduit coupled to supply a mobile phase to said stationary phase, first and second fluid reservoirs, a pump coupled to each reservoir to supply fluid from that reservoir to said conduit, a motor coupled to drive each pump, and means for controlling motor speed during delivery, refill and repressurization of each pump cycle to reduce pulsations in the system flow-rate, the improvement in said means for controlling comprising:

means for providing at least one signal representing pump flow-rate;
motor control means coupled to each pump motor and responsive to the flow-rate signal for driving the associated motor at a speed proportional to the flow-rate signal during the delivery period of the pump cycle and at an increased speed during the refill and repressurization periods of the pump cycle;
and
interface control means coupled to said motor control means and responsive to at least one flow-rate input signal for providing at least one repressurization signal causing at least one of said motor control means to increase motor speed during repressurization for a time period proportional to the magnitude of the repressurization signal.

1 more element

Dependencies are inferred from the claim text.

Pumping system

Life of this patent

Pumping system

Life of this patent

Abstract

Claims26