Warewash machine with soil detection

Abstract

A warewash machine includes a tank for holding liquid to be sprayed on items in a spray chamber and a recirculation line for delivering liquid from the tank to nozzles for spraying. A sensor arrangement is provided for monitoring condition of tank liquid, the sensor arrangement including an light emitter and a light receiver. A control is provided for energizing the light emitter and monitoring output of the light receiver, wherein the control is configured to vary the energization level of the light emitter during sensing to extend a useful range of measurement the sensor arrangement. The sensor arrangement may be located in line with or in parallel with a drain line of the tank.

1 . A warewash machine, comprising:
 a tank for holding liquid to be sprayed on items in a spray chamber;   a recirculation line for delivering liquid from the tank to nozzles for spraying;   a sensor arrangement for monitoring condition of tank liquid, the sensor arrangement including an light emitter and a light receiver; and   a control for energizing the light emitter and monitoring output of the light receiver, wherein the control is configured to vary the energization level of the light emitter during sensing.   
     
     
         2 . The machine of  claim 1  wherein the varying of the energization level of the light emitter produces a varied light intensity output by the light emitter. 
     
     
         3 . The machine of  claim 1  wherein the light emitter comprises multiple light elements and the energization level of the light emitter is varied by changing the number of light emitters that are energized. 
     
     
         4 . The machine of  claim 1 , wherein:
 the control is configured to energize the light emitter at a plurality of stepped energization levels.   
     
     
         5 . The machine of  claim 3  wherein:
 the control is configured to select one of the stepped energization levels for use in determining whether to take action based upon the output of the light receiver at the selected energization level. 
 
     
     
         6 . The machine of  claim 5 , wherein:
 the control is configured to select the stepped energization level at which the output of the light receiver is closest to a mid-range output of the light receiver.   
     
     
         7 - 8 . (canceled) 
     
     
         9 . The machine of  claim 1 , wherein:
 the control is configured to implement a ramped energization of the light emitter.   
     
     
         10 - 11 . (canceled) 
     
     
         12 . The machine of  claim 1 , wherein:
 the sensor arrangement is located along a path that is separate from and not parallel to the recirculation line, the control configured to implement a liquid monitoring operation after liquid travel along the path has stopped.   
     
     
         13 - 19 . (canceled) 
     
     
         20 . A warewash machine, comprising:
 a tank for holding liquid to be sprayed on items in a spray chamber;   a recirculation line for delivering liquid from the tank to nozzles for spraying;   a sensor arrangement for monitoring condition of tank liquid, the sensor arrangement including a light emitter and a light receiver; and   a control for monitoring output of the light receiver,   wherein the sensor arrangement is located along a path that is one of a drain line of the tank or a line in parallel with the drain line, the control configured to implement a liquid monitoring operation after liquid travel along the path has stopped.   
     
     
         21 . The machine of  claim 20  wherein the control is configured to implement a liquid monitoring operation after liquid travel along the path has stopped and a settling period has occurred. 
     
     
         22 . The machine of  claim 20 , wherein:
 the machine is a box-type machine and the monitoring occurs (1) during a recirculating washing operation and/or (2) during a drop down period following the recirculating washing operation.   
     
     
         23 . The machine of  claim 20 , wherein:
 the machine is a conveyor-type machine and the tank is associated with one of a pre-wash zone, wash zone or post-wash zone of the machine.   
     
     
         24 . The machine of  claim 20 , wherein:
 the control is configured to effect energization of the light emitter so as to produce a varying light intensity output from the light emitter.   
     
     
         25 . The machine of  claim 24 , wherein:
 the control is configured to effect energization of the light emitter so as to produce (i) a plurality of stepped light intensities or (ii) a ramped light intensity.   
     
     
         26 . The machine of  claim 22  wherein:
 the control is configured to effect one or more of the following operations based upon output from the sensor arrangement (i) frequency and/or duration of the recirculating washing operation of a cleaning cycle, (ii) drop down duration, (iii) frequency and/or duration of sump drainage, (iv) rinse duration and/or rinse water volume, (v) rinse aid dosing level, (vi) detergent dosing level, (vii) steam cycle, (viii) drying duration, (ix) interruption of the recirculating washing operation of a cleaning cycle with a partial drain followed by refill and continuation of the recirculating washing operation and/or (x) implementation of a partial or full drain after the recirculating washing operation of a cleaning cycle and repetition of the recirculating washing operation of the cleaning cycle before rinse. 
 
     
     
         27 . The machine of  claim 23 , wherein:
 the control is configured to effect one or more of the following operations based upon output from the sensor arrangement (i) dilution of pre-wash liquid, (ii) dilution of main wash liquid, (iii) dilution of post-wash liquid, (iv) conveyance speed, (v) partial or full tank drainage, (vi) final rinse flow rate, (vii) wash flow rate, (viii) rinse aid dosing and/or (ix) detergent dosing.   
     
     
         28 . The machine of  claim 20 , wherein:
 the control evaluates one or more of (1) discrete output level of the light receiver at one or more points in time, (2) a rate of change in output level of the light receiver with respect to time and/or (3) a variance in output level of the light receiver within a set period of time.   
     
     
         29 . The machine of  claim 20 , wherein:
 the sensor arrangement includes vertically spaced light emitter-light receiver pairs at different heights in a sampling zone.   
     
     
         30 . The machine of clam  29 , wherein:
 the sensor arrangement is formed by a clear tubing structure with a sensor module mounted thereto, the clear tubing structure forming part of the path.   
     
     
         31 . The machine of  claim 30 , wherein:
 the light emitter is located on one side of the clear tubing structure and the light receiver is located at an opposite side of the clear tubing structure.