Patent Publication Number: US-2007102030-A1

Title: Dishwasher having a variable speed circulation pump controlled responsive to sensed turbidity

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
      This application is a continuation application of application Ser. No. 10/280,357, filed Oct. 25, 2002, the entire disclosure of which is hereby incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION  
      The present invention relates to dishwashers, and particularly relates to dishwashers that sense turbidity of washing liquid within the dishwasher.  
     BACKGROUND OF THE INVENTION  
      The soil removing ability of a dishwasher is related to the hydraulic force and/or volume of washing fluid that is applied to the dishes that are to be washed. Hydraulic force and/or volume are related to the size, operating capacity, etc. of the pump moving the washing fluid. Typically, a specific level of hydraulic force and/or volume output from a pump has an associated level of output noise and energy consumption by the pump.  
     BRIEF SUMMARY OF THE INVENTION  
      In accordance with one aspect, the present invention provides a dishwasher that includes an enclosure within which dishes are washed with a wash liquid. A pump moves the wash liquid to wash the dishes within the enclosure. The pump has a plurality of operational states. A sensor senses turbidity within the wash liquid. The dishwasher includes means to control the operational state of the pump in response to the sensed turbidity.  
      In accordance with another aspect, the present invention provides a dishwasher that includes an enclosure within which dishes are washed with a wash liquid. A pump moves the wash liquid. The pump has a plurality of fluid flow output rates. A sensor senses turbidity within the wash liquid. The dishwasher includes means to control the output flow rate of the pump in response to the sensed turbidity. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The forgoing and other features and advantages of the present invention will become apparent to those skilled in the art to which the present invention relates upon reading the following description with reference to the accompanying drawings, wherein:  
       FIG. 1  is a schematic illustration of a dishwasher having a variable speed circulation pump and a turbidity sensor for use in control of the pump in accordance with the present invention; and  
       FIG. 2  is a flow chart for a process in accordance with the present invention.  
    
    
     DESCRIPTION OF EXAMPLE EMBODIMENTS  
      One example of dishwasher  10 , in accordance with the present invention, is schematically shown in  FIG. 1 . The dishwasher  10  has an enclosure  12  within which dishes (e.g., plates, cups, bowls, tableware, pots, pans, etc.) are placed for cleaning. In the illustrated example, the dishwasher  10  has racks  14  for supporting the dishes. Also, the dishwasher  10  has washing liquid (e.g., water and detergent) delivery components  16 , such as spray heads or spray arms. The dishwasher  10  may have other and/or different structure(s).  
      During operation, the washing liquid is circulated within the dishwasher  10  via a pump  20 . In the shown example, the pump  20  draws the wash liquid from a sump area  22  (e.g., a low area of the enclosure  12 ) and supplies the wash liquid, via connecting hoses/pipes  24  to the delivery components  16 . In turn the wash liquid is applied to the dishes via the delivery components  16  and subsequently falls to the sump area  22 . The wash liquid undergoes a plurality of circulations.  
      During the washing of the dishes, particulate matter (e.g., food residue) is washed from the dishes and is carried away from the dishes by the wash liquid. The particulate matter provides a level of turbidity within the washing liquid. Hereinafter, the particulate matter level within the washing liquid is referred to as turbidity. The turbidity may be indicative of the level of cleanness of the dishes. It has been appreciated by the inventor that cleaning of dishes is affected by the volume and/or pressure of the wash liquid applied to the dishes. Also, it has been appreciated by the inventor that energy consumption and output noise levels are related to pump operation.  
      In accordance with the present invention, the volume and/or pressure of the wash liquid applied to the dishes is changed in response to the turbidity of the washing liquid. Specifically, the pump  20  is configured to have a plurality of operational states that each provides a different output flow rate (e.g., flow volume and/or speed) of the wash liquid. The output flow rate can also be considered in terms of hydraulic pressure. A turbidity sensor  28  senses the turbidity of the wash liquid. The sensed turbidity  28  is used to control the operational state of pump  20 .  
      In the shown example, the pump  20  includes a pump motor  30  that has a plurality of operation speeds. As such, the motor  30  is referred to as a variable speed motor. In particular, the motor  30  has at least two speeds (e.g., low and high). In one example, a low speed would be for very quiet washing and the high speed would be for ultra scrubbing power.  
      A controller  32  is operatively connected  34  to the turbidity sensor  28 , to receive a signal indicative of the sensed turbidity. The controller  32  is operatively connected  36  to the pump motor  30  to control the pump motor in response to the sensed turbidity. The controller  32  may have any suitable construction and configuration for controlling the motor  30  in response to the sensed turbidity. In the shown example, the controller  32  has a portion  40  for determining the turbidity level using the signal from the turbidity sensor  28 . A portion  42  of the controller  32  controls pump speed, and is operatively connected  44  to the turbidity level determination portion  40  and operatively connected  36  to the pump motor  30 . In the shown example, a motor sensor  46  (e.g., a Hall effect sensor) senses the operation speed of the motor  30  and is operatively connected  48  to the pump speed control portion  42 . As such, a feedback or monitor aspect can be utilized in the control of the pump speed.  
      In the shown example, a manual override portion  50  of the controller  32  is operatively connected  52  to the pump speed control portion  42 . The manual override portion  50  is operatively connected  54  to a manual override selection component  56  (e.g., a selection switch). A manual override allows a user to select pump speed that is not dependent upon the sensed turbidity level.  
      It is to be appreciated the controller  32  may have other components and/or functions. Specifically, in the shown example, the controller  32  has portion(s)  58  that utilize the determined turbidity level to control other aspects of the dishwasher. For example, the turbidity level may be utilized to determine whether to input fresh water.  
      Turning to the determination(s) that are utilized for changing operational speed of the pump motor  30 , it is to be appreciated that any suitable determination(s) may be utilized. For example, a determination of whether the turbidity level has exceed a preset threshold may be used.  
      An example of a process performed by the dishwasher of  FIG. 1 , in accordance with the present invention, is shown in  FIG. 2 . The process  100  is initiated at step  102  and proceeds to step  104 . At step  104  the pump is operated at a first speed. At step  106 , the turbidity is sensed. At step  108 , it is determined in the turbidity is above a threshold value.  
      If the determination at step  108  is affirmative (i.e., the turbidity is above the threshold), then the process  100  loops to step  106 . The pump speed is not changed, and the turbidity is again sensed, at step  106 , and compared to the threshold, at step  108 .  
      If the determination at step  108  is negative (i.e., the turbidity is at or below the threshold), the process proceeds to step  110 . At step  110 , the pump is set to a second speed. The process  100  ends at set  112 .  
      From the above description of the invention, those skilled in the art will perceive improvements, changes and modifications. Such improvements, changes and modifications within the skill of the art are intended to be covered by the appended claims.