Warewash machine system and method for detecting clogged wash arm

Abstract

A method of detecting a clogged or partially clogged wash arm in a warewash machine involves the steps of: monitoring a rotational speed of the wash arm during a washing step of aware cleaning cycle or operation; and comparing the monitored rotation speed to a set threshold speed and, if the monitored rotational speed falls below the set threshold speed, triggering an operator alert to advise the machine operator to check the wash arm. An advantageous sensor arrangement associated with a wash arm manifold is also provided.

What is claimed is: 
     
         1 . A method of automated operation of a warewash machine that includes a chamber for receiving wares to be washed, a wash arm mounted for rotation within the chamber and including multiple nozzles for spraying wash liquid, the method including:
 delivering a recirculated wash liquid to the wash arm for spraying during a ware cleaning operation;   monitoring rotational speed of the wash arm during the delivering step;   comparing the monitored rotational speed to a set threshold speed that is greater than zero speed; and   if the monitored rotational speed falls below the set threshold speed, triggering an operator alert to advise the machine operator to check the wash arm.   
     
     
         2 . The method of  claim 1  wherein the set threshold speed corresponds to a speed above which wares are adequately cleaned and below which wares are not adequately cleaned as determined by prior testing. 
     
     
         3 . The method of  claim 1  wherein the monitoring step is carried out utilizing a magnet located on a rotatable hub member to which the wash arm is mounted and a magnetic detector mounted in a manifold that feeds water to the wash arm. 
     
     
         4 . The method of  claim 3  wherein the manifold includes a first portion internal of the chamber and a second portion external of the chamber, and the magnetic detector is mounted into the manifold through a slot or opening that is accessed via the second portion and that extends up into the first portion. 
     
     
         5 . The method of  claim 1  wherein a controller of the machine is configured such that the operator alert is only communicated after the ware cleaning operation is completed. 
     
     
         6 . The method of  claim 1  wherein the machine includes multiple wash arms and the operator alert identifies a specific one of the wash arms that should be checked. 
     
     
         7 . The method of  claim 1  wherein the machine includes multiple wash arms that are monitored, and each wash arm has a corresponding set threshold speed stored in memory of a controller of the machine. 
     
     
         8 . A warewash machine, comprising:
 a chamber for receiving wares to be washed, the chamber accessible via a door;   a wash arm in the chamber, the wash arm mounted to a rotatable hub member, the wash arm including multiple nozzles for spraying recirculated wash liquid, the rotatable hub member including a trigger element thereon;   a manifold for delivering wash liquid to the wash arm, the manifold including a detector positioned for detecting the trigger element as it rotates past the detector;   a controller connected with the detector to monitor wash arm rotational speed, the controller configured to responsively identify a clogged or potentially clogged condition of the wash arm.   
     
     
         9 . The warewash machine of  claim 8  wherein the trigger element is an RF element and the detector is an RF detector. 
     
     
         10 . The warewash machine of  claim 8  wherein the trigger element is a magnet and the detector is a magnetic detector. 
     
     
         11 . The warewash machine of  claim 10  wherein the manifold includes a first portion internal of the chamber and a second portion external of the chamber, and the magnetic detector is mounted into the manifold through a slot or opening that is accessed via the second portion and that extends up into the first portion. 
     
     
         12 . The warewash machine of  claim 8  wherein the controller is configured to compare the monitored rotational speed to a set threshold speed and, if the monitored rotational speed falls below the set threshold speed, to trigger an operator alert to advise the machine operator to check the wash arm. 
     
     
         13 . The warewash machine of  claim 12  wherein the set threshold speed corresponds to a speed above which wares are adequately cleaned and below which wares are not adequately cleaned. 
     
     
         14 . The warewash machine of  claim 12  wherein the controller is configured such that the operator alert is only delivered after a ware cleaning cycle is completed so to limit the likelihood that the machine operator will stop the machine during the ware cleaning cycle. 
     
     
         15 . A warewash machine, comprising:
 a chamber for receiving wares to be washed, the chamber accessible via a door;   a wash arm in the chamber, the wash arm mounted to a rotatable hub member, the wash arm including multiple nozzles for spraying recirculated wash liquid, the rotatable hub member including a trigger element thereon;   a manifold for delivering wash liquid to the wash arm, the manifold including a detector positioned for detecting the trigger element as it rotates past the detector, wherein the manifold includes a first portion internal of the chamber and a second portion external of the chamber, and the detector is mounted into the manifold through a slot or opening that is accessed via the second portion and that extends up into the first portion so that the detector can be accessed and/or replaced from external of the chamber;   a controller connected with the detector to monitor wash arm rotational speed.   
     
     
         16 . The warewash machine of  claim 12  wherein the trigger element is an RF element and the detector is an RF detector. 
     
     
         17 . The warewash machine of  claim 12  wherein the trigger element is a magnet and the detector is a magnetic detector. 
     
     
         19 . The warewash machine of  claim 12  wherein the controller is configured to compare the monitored rotational speed to a set threshold speed and, if the monitored rotational speed falls below the set threshold speed, to trigger an operator alert to advise the machine operator to check the wash arm. 
     
     
         20 . The warewash machine of  claim 19  wherein:
 the set threshold speed corresponds to a speed above which wares are adequately cleaned and below which wares are not adequately cleaned; and 
 the controller is configured such that the operator alert is only delivered after a ware cleaning cycle is completed so to limit the likelihood that the machine operator will stop the machine during the ware cleaning cycle.