Self-optimizing detergent controller for minimizing detergent set-point overshoot
First Claim
1. An apparatus for optimizing detergent concentration in a warewashing machine with minimal overshoot, comprising:
- means for determining whether a detergent needs to be added to a wash solution;
means for feeding the detergent into the wash solution;
sensor means for measuring a detergent concentration in the wash solution;
means for calculating a rate of increase for the detergent concentration in the wash solution; and
means for determining an appropriate on-time and off-time for the means for feeding using derivative control, wherein the appropriate on-time and off-time is determined based on balancing the rate of increase for the detergent concentration in the wash solution and compensation for any latency time with a need to minimize overshoot in the detergent concentration wherein the means for determining further comprises means for discontinuing the means for feeding when overshoot in the detergent concentration is anticipated based upon the rate of increase.
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Abstract
An apparatus and method for programming a detergent controller to vary the detergent concentration set-point according to the time of day and to achieve detergent concentration levels quickly without incurring overshoot. Thus, the present invention insures that the warewashing machine is operated at optimum efficiency and cost. To vary the set-point according to the time of day, the invention combines the features of a microprocessor, a clock and a controller into one unit. The user enters the time setting and set point into the controller. The microprocessor then compares the real-time clock signal with the user time settings and outputs an appropriate set-point value from the microprocessor to the controller. To achieve detergent concentration levels quickly without incurring overshoot, the controller senses the detergent concentration and dispenses the proper detergent level to the warewashing machine according to a predetermined detergent feed time based on the previous response time and the programmed set-point. Thus, the controller can change the response function if and when conditions change.
80 Citations
14 Claims
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1. An apparatus for optimizing detergent concentration in a warewashing machine with minimal overshoot, comprising:
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means for determining whether a detergent needs to be added to a wash solution; means for feeding the detergent into the wash solution; sensor means for measuring a detergent concentration in the wash solution; means for calculating a rate of increase for the detergent concentration in the wash solution; and means for determining an appropriate on-time and off-time for the means for feeding using derivative control, wherein the appropriate on-time and off-time is determined based on balancing the rate of increase for the detergent concentration in the wash solution and compensation for any latency time with a need to minimize overshoot in the detergent concentration wherein the means for determining further comprises means for discontinuing the means for feeding when overshoot in the detergent concentration is anticipated based upon the rate of increase. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of optimizing detergent concentration in a warewashing machine using a controller, comprising the steps of:
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determining, in the controller, whether a detergent needs to be added to a wash solution in the warewashing machine; feeding the detergent into the wash solution under a control of the controller; measuring, in the controller, a detergent concentration in the wash solution using a sensor coupled to the controller; calculating, in the controller, a rate of increase for the detergent concentration in the wash solution; and determining, in the controller, an appropriate on-time and off-time for the feeding step, wherein the appropriate on-time and off-time is determined based on balancing the rate of increase for the detergent concentration in the wash solution and compensation for any latency time with a need to minimize overshoot in the detergent concentration, wherein the determining in the controller an appropriate on-time and off-time step further comprises a step of discontinuing the feeding step when overshoot in the detergent concentration is anticipated based upon the rate of increase. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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Specification