US 5,475,614 A · Method and apparatus for controlling a variable fluid delivery system

Abstract

A fluid delivery control system is provided for controlling a fluid delivery system to deliver a fluid under pressure at a target flow rate. In a hybrid mode, the preferred fluid delivery control system is responsive to signals from a pressure sensor and a flowmeter. Primary feedback control is provided using the sensed pressure from the pressure sensor, and the sensed flow rate from the flowmeter is utilized to provide compensation for the pressure responsive feedback control and to provide accurate measurements of flow rate and total flow for the fluid delivery system. The preferred fluid delivery control system is also capable of operating in flowmeter and pressure modes which are only responsive to signals from a flowmeter and a pressure sensor, respectively. In the preferred embodiment, the fluid delivery control system is utilized in a mobile sprayer system for applying an agent over a surface. A constant application rate of agent over the surface is maintained by varying the delivery rate of the fluid delivery system with the speed of the sprayer system.

Claims21

Dependent claims

A fluid delivery system for delivering a fluid to an output at a target flow rate, comprising:

(a) delivery means for providing a fluid under pressure to an output, the delivery means being controllable to deliver the fluid at a plurality of delivery rates;
(b) a pressure sensor configured to provide a pressure signal representative of fluid pressure in the delivery means;
(c) a flowmeter configured to provide a flow rate signal representative of fluid flow rate in the delivery means;
(d) control means, responsive to the pressure signal, for controlling the delivery means to deliver fluid to the output at the target flow rate, wherein the target flow rate and the pressure signal are related by a control equation having a compensation factor;
and
(e) compensation means for controlling the compensation factor to vary the responsiveness of the control equation in response to deviations between a flow rate value calculated from the pressure signal and a flow rate value measured from the flow rate signal.

3 more elements

A fluid delivery system for delivering a fluid to an output at a target flow rate, comprising:

(a) delivery means for providing a fluid under pressure to an output the delivery means being controllable to deliver the fluid at a plurality of delivery rates;
(b) a pressure sensor configured to provide a pressure signal representative of fluid pressure in the delivery means:
(c) a flowmeter configured to provide a flow rate signal representative of fluid flow rate in the delivery means:
(d) control means, responsive the pressure signal, for controlling the delivery means to deliver fluid to the output at the target flow rate by comparing the pressure signal with a target pressure computed from the target flow rate, wherein the target flow rate and the pressure signal are related by a control equation, wherein the target pressure is related to the target flow rate by the equation:
##EQU7## wherein the nozzle factor is a constant representative of the relationship between flow rate and the square root of pressure in the delivery means, and wherein the delta nozzle factor is representative of an error in the nozzle factor;
and
(e) compensation means for controlling the delta nozzle factor to vary the responsiveness of the control equation in response to deviations between a flow rate value calculated from the pressure signal and a flow rate value measured from the flow rate signal.

4 more elements

A sprayer control system for controlling a sprayer delivery system to deliver an agent from a source of agent to an output at a target application rate, wherein the sprayer delivery system is of the type which is controllable to provide an agent under pressure at a plurality of delivery rates, the sprayer control system comprising:

(a) pressure sensing means for providing a pressure signal representative of agent pressure in the sprayer delivery system;
(b) flow rate sensing means for providing a flow rate signal representative of agent flow rate in the sprayer delivery system;
(c) control means for controlling the sprayer delivery system to deliver agent at the target application rate, wherein the control means includes error determining means, responsive to the pressure signal, for determining error between a flow rate sensed by the pressure sensing means and the target application rate;
and
(d) compensation means, responsive to the flow rate signal, for varying the responsiveness of the error determining means to the pressure signal, to compensate for variations between the flow rate sensed by the pressure sensing means and an actual flow rate sensed by the flow rate sensing means.

2 more elements

A method for controlling a delivery system to deliver a fluid to an output at a target flow rate, wherein the delivery system is of the type which is controllable to provide a fluid under pressure at a plurality of delivery rates, the method comprising the steps of:

(a) sensing fluid pressure in the delivery system and providing a pressure signal representative thereof;
(b) sensing fluid flow rate in the delivery system and providing a flow rate signal representative thereof;
(c) controlling the delivery system to deliver fluid at the target flow rate responsive to the pressure signal, wherein the target flow rate and pressure signal are related by a control equation, the controlling step including the steps of:
(1) comparing the pressure signal with a target pressure, wherein the target pressure is computed from the target flow rate using the control equation, the control equation having a nozzle factor constant representative of the relationship between flow rate and the square root of pressure in the delivery system, and a delta nozzle factor representative of error in the nozzle factor;
(2) computing the percent error between the target pressure and the pressure signal from the pressure sensor;
and
(3) regulating pressure in the delivery system responsive to the percent error between the target pressure and the pressure signal;
and
(d) varying the responsiveness of the control equation responsive to the flow rate signal to compensate for variations between a flow rate value calculated from the pressure signal and the actual flow rate determined from the flow rate signal.

6 more elements

Dependencies are inferred from the claim text.

Method and apparatus for controlling a variable fluid delivery system

Life of this patent

Method and apparatus for controlling a variable fluid delivery system

Life of this patent

Abstract

Claims21