Closed loop control of compressible fluid addition to a mixture of such fluid and a liquid
AssigneeCincinnati Milacron Inc.
InventorsGilbert R. Belangee, Robert J. Dransman, Kirby L. Stone
Life of this patent
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Abstract
In reaction injection molding facilities of the recirculation type, a closed loop system controls the addition of a gas to a mixture of liquid and gas. The system takes a sample volume of the liquid and forces a plunger into the sample volume. The distance travelled by the plunger between two preset pressures of the sample is measured and compared to a reference distance to get a control signal that is used to operate a valve that controls gas admission to the mixture.
Claims22
A closed loop apparatus to control the flow of a gas into a liquid in automatic response to a determination or measurement of the gas in a sample of a mixture of said gas and said liquid comprising
- a recirculation system for said mixture having connected in series a source for said mixture, a place of use of said mixture, and a metering pump which has a plunger reciprocatable in a chamber;
- first, second and third conduit means connected, respectively, between said source and said place, said place and said pump, and said pump and said source;
- means for adding gas to liquid connected into at least one of said recirculation system and conduit means;
- means to trap a sample of said mixture within said metering pump responsive to a trap signal to do so and to untrap such a sample responsive to another signal;
- means to determine the actual distance moved by said plunger in said chamber to change the pressure of said sample from a first preselected pressure to a second preselected pressure and to produce an actual distance signal representative of said actual distance;
- means to combine said actual distance signal with a set point signal to produce a control signal;
- means to control the gas flow to said means for adding gas in response to said control signal;
- and
- means to transmit the respective signals from where produced to where utilized.
A process for closed loop control of the addition of a first fluid to a second or to a mixture of the aforesaid fluids to make a compressible mixture comprising the steps of
- providing, respectively, a trap chamber that includes a plunger reciprocable therein, means to add said first fluid into a fluid selected from the group consisting of said second fluid and a mixture of said first and second fluids to form said compressible mixture of fluids, and control means responsive to positioning of said plunger in said trap chamber for manipulating said means to add;
- trapping a sample of said mixture in said trap chamber;
- advancing said plunger into said chamber to change the pressure of said sample from a first preselected pressure to a second preselected pressure that is higher;
- producing an actual distance signal representative of the amount said plunger is advanced while changing the sample pressure as aforesaid;
- combining said actual distance signal with a set point signal to produce a control signal, said set point signal having been stored in said control means and producing a control signal representative of at least a portion of any difference between the signals so combined;
- and
- controlling the flow of said first fluid into said fluid selected from said group by applying said control signal to said control means.
Apparatus to provide a control signal representative of the compressability of gas and liquid mixture comprising
- a plunger reciprocable within a trap chamber;
- means to provide an actual distance signal representative of the actual amount said plunger advances into said trap chamber to change the pressure therein from a first preselected pressure to a second and higher preselected pressure;
- means to store and provide a set point signal representative of a preselected amount of such plunger advance;
- and
- means to compare said set point signal with said actual distance signal and produce a control signal representative of the comparison.
A closed loop system for circulating a fluid from a source to a place of use and recirculating to said source from said place so much of said fluid and as is not consumed at said place of use and comprising
- adding means for adding a compressible fluid to said fluid;
- control means for controlling said adding means;
- trap means for trapping a sample that is representative of said fluid;
- means to compress said sample by forcing a member thereinto;
- means to determine the actual distance travelled by said member to change the pressure in said sample by some predetermined amount and to provide a distance signal representative of said distance travelled;
- computing means to obtain a control signal from said distance signal from said measuring means;
- and
- means to apply said control signal to said control means;
- whereby closed loop feedback control of the addition of said compressible fluid to said fluid is achieved.
Dependencies are inferred from the claim text.