Rinse aid release detection method

• US 8,540,820 B2
• Filed: 10/21/2009
• Issued: 09/24/2013
• Est. Priority Date: 10/21/2009
• Status: Active Grant

• Current Assignee: Whirlpool Corporation
• Original Assignee: Whirlpool Corporation
• Inventors: Lau, Brooke L., Allen, Douglas T., King, Jonathan D., Szostak, Jacek
• Primary Examiner(s): Kornakov, Michael
• Assistant Examiner(s): WHATLEY, KATELYN B
• Application Number:
  US12/582,789
• Publication Number:
  US 20110088724A1
• Time in Patent Office: 1,434 Days
• Field of Search: 134/18, 134/58.D, 134/56.D
• US Class Current: 134/18
• CPC Class Codes: A47L 15/0034 Drying phases, including dripping-off phases
• CPC Class Codes: A47L 15/0055 Metering or indication of used products, e.g. type or quantity of detergent, rinse aid or salt; for measuring or controlling the product concentration
• CPC Class Codes: A47L 15/4221 Arrangements for redirection of washing water, e.g. water diverters to selectively supply the spray arms A47L15/0078 takes precedence
• CPC Class Codes: A47L 15/4297 Arrangements for detecting or measuring the condition of the washing water, e.g. turbidity
• CPC Class Codes: A47L 2401/023 Quantity or concentration of the consumable product
• CPC Class Codes: A47L 2401/10 Water cloudiness or dirtiness, e.g. turbidity, foaming or level of bacteria
• CPC Class Codes: A47L 2501/03 Water recirculation, e.g. control of distributing valves for redirection of water flow
• CPC Class Codes: A47L 2501/07 Consumable products, e.g. detergent, rinse aids or salt
• CPC Class Codes: A47L 2501/30 Regulation of machine operational steps within the washing process, e.g. performing an additional rinsing phase, shortening or stopping of the drying phase, washing at decreased noise operation conditions

Abstract

A dishwashing machine configured to detect the presence of rinse aid in fluid in a washing chamber of the dishwashing machine. An electronic controller selects the drying stage of the dishwashing cycle based on whether rinse aid is present.

Claims

1. A method of detecting a rinse aid in a dishwashing cycle, comprising:

determining a first turbidity level of fluid in a washing chamber during a rinsing stage of a dishwashing cycle and while the fluid is being sprayed into the washing chamber,

generating a control signal to operate a dispenser during the rinsing stage,

determining a second turbidity level of fluid in the washing chamber after generation of the control signal and while the fluid is being sprayed into the washing chamber,

determining if a rinse aid is present in fluid in the washing chamber based on the first turbidity level and the second turbidity level by;

determining whether the second turbidity level is greater than or equal to the first turbidity level, calculating a difference between the second turbidity level and the first turbidity level when the second turbidity level is greater than or equal to the first turbidity level, and concluding the rinse aid is present when the difference between the second turbidity level and the first turbidity level exceeds a predetermined threshold value, and

selecting a drying stage of the dishwashing cycle based on whether rinse aid is present.

2. The method of claim 1, wherein determining if the rinse aid is present includes:

comparing the second turbidity level to the first turbidity level, and

concluding the rinse aid is not present if the second turbidity level is less than the first turbidity level.

3. The method of claim 1, wherein selecting the drying stage of the dishwashing cycle includes selecting a standard drying stage having a standard duration and a standard temperature if the rinse aid is not present in fluid.

4. The method of claim 3, wherein selecting the drying stage of the dishwashing cycle includes selecting a modified drying stage having a duration less than the standard duration if the rinse aid is present in fluid.

5. The method of claim 3, wherein selecting the drying stage of the dishwashing cycle includes selecting a modified drying stage having a temperature less than the standard temperature if the rinse aid is present in fluid.

6. The method of claim 1, further comprising:

supplying fluid alternately to an upper spray arm and a lower spray arm such that the upper spray arm and the lower spray arm alternately circulate fluid in a washing chamber,

suspending the supply of fluid to the lower spray arm before determining the first turbidity level such that fluid is circulated continuously from the upper spray arm, and

resuming the supply of fluid to the lower spray arm after determining the second turbidity level.

7. A method of performing a rinsing operation in a dishwashing machine including a tub defining a washing chamber, a number of dish racks positioned in the washing chamber, a pump operable to circulate fluid onto the number of dish racks during a dishwashing cycle, a turbidity sensor operable to measure turbidity of fluid in the washing chamber and generate an electrical output signal indicative thereof, an electronic controller, electrically coupled to the turbidity sensor, including (i) a processor, and (ii) a memory device electrically coupled to the processor, the memory device having stored therein a plurality of instructions for execution by the processor, an electronically-controlled dispenser electrically coupled to the controller and having a receptacle formed therein configured receive a rinse aid and a hatch extending over an opening defined in a front surface of the receptacle, and an electric heating element electrically coupled to the controller and configured to heat fluid in the washing chamber, said method comprising:

(a) causing the controller to communicate with the turbidity sensor to determine a turbidity level of fluid in the washing chamber by;

operating the electric heating element to heat fluid in the washing chamber to a first temperature, communicating with the turbidity sensor to determine a first turbidity level of fluid in the washing chamber at the first temperature and before the rinse aid is added to the washing chamber, causing the controller to operate the dispenser to open the hatch such that rinse aid may pass from the dispenser into the washing chamber, determining a second turbidity level of fluid in the washing chamber, and calculating a difference between the second turbidity level and the first turbidity level,

(b) determining a presence of a rinse aid in fluid in the washing chamber based on the turbidity level,

(c) heating fluid in the washing chamber to a second temperature,

(d) completing the rinsing operation, and

(e) modifying a drying stage of the dishwashing cycle when rinse aid has been determined to be present in the fluid.

8. The method of claim 7, further comprising:

determining the rinse aid is present when a difference between the second turbidity level and the first turbidity level is greater than a predetermined threshold value.

9. The method of claim 7, wherein the dishwasher further includes:

a lower spray arm positioned below one of the number of dishracks, the lower spray arm being fluidly coupled to the pump to circulate fluid;

an upper spray arm positioned above the lower spray arm, the upper spray arm being fluidly coupled to the pump to alternately circulate fluid with the lower spray arm; and

a diverter valve electrically coupled to the controller and configured to alternately supply fluid to the upper spray arm and the lower spray arm, and said method further comprises;

(a) operating the diverter valve to suspend the supply of fluid to the lower spray arm such that the upper spray arm continuously circulates fluid,

(b) communicating with the turbidity sensor to determine the first turbidity level and second turbidity level while the upper spray arm continuously circulates fluid, and

(c) operating the diverter valve to resume the supply of fluid to the lower spray arm such that the lower spray arm alternately circulates fluid with the upper spray arm.