Dishwasher with turbidity sensing mechanism
First Claim
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1. A dishwasher comprising:
- a wash chamber for receiving fluid and articles to be washed in the fluid;
a spray mechanism for spraying fluid into said chamber to remove soil from articles therein;
a pump connected to said chamber, a conduit connecting said pump to said spray mechanism;
said pump being selectively operable to withdraw fluid from said chamber and to supply the fluid to said spray mechanism through said conduit;
a turbidity sensing mechanism including a transparent tube in fluid flow relationship with said conduit between said pump and said spray mechanism;
a source of electromagnetic radiation directed into the fluid in said tube;
a sensor detecting electromagnetic radiation propagated through the fluid in said tube and providing a frequency signal representative of the turbidity of the fluid in said tube;
said turbidity sensing mechanism includes an elongated housing connected in said conduit, said transparent tube being mounted within said housing in fluid flow relationship with said conduit;
said housing defining a cavity therein around said tube;
said source of electromagnetic radiation being mounted in said cavity adjacent said tube and said sensor being mounted in said cavity adjacent said tube substantially opposite said source.
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Abstract
A turbidity sensing mechanism for a dishwasher is connected in the fluid circulation conduit between the pump and the spray mechanism. The mechanism includes a hollow housing enclosing a hollow transparent tube connected in fluid flow relationship with the conduit. A source of electromagnetic radiation and a radiation-to-frequency sensor are positioned inside the housing on opposite sides of the tube.
86 Citations
10 Claims
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1. A dishwasher comprising:
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a wash chamber for receiving fluid and articles to be washed in the fluid; a spray mechanism for spraying fluid into said chamber to remove soil from articles therein; a pump connected to said chamber, a conduit connecting said pump to said spray mechanism;
said pump being selectively operable to withdraw fluid from said chamber and to supply the fluid to said spray mechanism through said conduit;a turbidity sensing mechanism including a transparent tube in fluid flow relationship with said conduit between said pump and said spray mechanism;
a source of electromagnetic radiation directed into the fluid in said tube;
a sensor detecting electromagnetic radiation propagated through the fluid in said tube and providing a frequency signal representative of the turbidity of the fluid in said tube;said turbidity sensing mechanism includes an elongated housing connected in said conduit, said transparent tube being mounted within said housing in fluid flow relationship with said conduit; said housing defining a cavity therein around said tube; said source of electromagnetic radiation being mounted in said cavity adjacent said tube and said sensor being mounted in said cavity adjacent said tube substantially opposite said source. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A dishwasher comprising:
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a wash chamber for receiving fluid and articles to be washed in the fluid; a spray mechanism for spraying fluid into said chamber to remove soil from articles therein; a pump connected to said chamber, a conduit connecting said pump to said spray mechanism;
said pump being selectively operable to withdraw fluid from said chamber and to supply the fluid to said spray mechanism through said conduit;a turbidity sensing mechanism including a transparent tube in fluid flow relationship with said conduit between said pump and said spray mechanism;
a source of electromagnetic radiation directed into the fluid in said tube;
a sensor detecting electromagnetic radiation propagated through the fluid in said tube and providing a frequency signal representative of the turbidity of the fluid in said tube;a water inlet mechanism for supplying fluid to said chamber; drain mechanism for evacuating fluid from said chamber; a controller responsive to frequency signals from said sensor and effective to cause said dishwasher to execute a washing sequence of a series of operations, each operation including a step of supplying fluid to said chamber, a step of circulating the fluid and a step of evacuating the fluid from said chamber; said controller being operative to calibrate said sensor by repeatedly sampling the frequency signals from said sensor, over a measurement interval prior to the circulating step of the initial operation of a washing sequence, determining whether the value of that frequency signal is within a predetermined band of frequency signal values; and
repeatedly varying the measurement interval over which the frequency signal is measured until the frequency signal value is within the predetermined band of frequency signal values; and
storing the measurement interval over which the frequency signal value that is within the predetermined band of frequency signal values is measured for use as the measurement interval when subsequently sampling the frequency signal from said sensor to obtain liquid turbidity measurements during the balance of the washing sequence.
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Specification