Dishwashing appliance and siphoning prevention

Abstract

A dishwashing appliance may include a cabinet, a tub, a spray assembly, a drain pump, and a controller. The tub may be positioned within the cabinet and define a wash chamber. The spray assembly may be positioned within the wash chamber. The drain pump may be in fluid communication with the wash chamber. The controller may be configured to initiate a washing operation. The washing operation may include activating the drain pump for an activation period, deactivating the drain pump for a deactivation period, detecting a first water condition upstream from the drain pump during the deactivation period, detecting, following detecting the first water condition, a second water condition upstream from the drain pump during the deactivation period, comparing the second water condition to the first water condition, and directing the drain pump based on the comparison of the second water condition to the first water condition.

1 . A dishwashing appliance, comprising:
 a cabinet;   a tub positioned within the cabinet and defining a wash chamber for receipt of articles for washing;   a spray assembly positioned within the wash chamber;   a drain pump in fluid communication with the wash chamber; and   a controller in operative communication with the drain pump, the controller being configured to initiate a washing operation, the washing operation comprising
 activating the drain pump for an activation period, 
 deactivating the drain pump for a deactivation period, 
 detecting a first water condition upstream from the drain pump during the deactivation period, 
 detecting, following detecting the first water condition, a second water condition upstream from the drain pump during the deactivation period, 
 comparing the second water condition to the first water condition, and 
 directing the drain pump based on the comparison of the second water condition to the first water condition. 
   
     
     
         2 . The dishwashing appliance of  claim 1 , wherein the first water condition is a first pressure (P 1 ), and wherein the second water condition is a second pressure (P 2 ). 
     
     
         3 . The dishwashing appliance of  claim 2 , further comprising:
 a pressure sensor disposed upstream from the drain pump,   wherein the first pressure is detected at the pressure sensor, and   wherein the second pressure is detected at the pressure sensor.   
     
     
         4 . The dishwashing appliance of  claim 1 , wherein comparing the second water condition to the first water condition comprises determining the second water condition is less than a variable threshold relative to the first water condition. 
     
     
         5 . The dishwashing appliance of  claim 1 , wherein directing the drain pump comprises reactivating the drain pump. 
     
     
         6 . The dishwashing appliance of  claim 5 , wherein reactivating the drain pump is for a reactivation period. 
     
     
         7 . The dishwashing appliance of  claim 6 , wherein the reactivation period is limited to a predetermined time period for reactivation, and wherein the washing operation further comprises deactivating, again, the drain pump in response to expiration of the predetermined time period for reactivation. 
     
     
         8 . The dishwashing appliance of  claim 1 , wherein the washing operation further comprises
 activating a circulation pump following reactivating the drain pump.   
     
     
         9 . The dishwashing appliance of  claim 1 , wherein the washing operation further comprises
 measuring expiration of a set period following detecting the first water condition,   wherein detecting the second water condition is in response to measuring expiration of the set period.   
     
     
         10 . A method of operating a dishwashing appliance comprising a sump and a drain pump downstream from the sump, the method comprising:
 activating the drain pump for an activation period;   deactivating the drain pump for a deactivation period;   detecting a first water condition upstream from the drain pump during the deactivation period;   detecting, following detecting the first water condition, a second water condition upstream from the drain pump during the deactivation period;   comparing the second water condition to the first water condition; and   directing the drain pump based on the comparison of the second water condition to the first water condition.   
     
     
         11 . The method of  claim 10 , wherein the first water condition is a first pressure (P 1 ), and wherein the second water condition is a second pressure (P 2 ). 
     
     
         12 . The method of  claim 11 , wherein the first pressure is detected at a pressure sensor mounted within the sump, and wherein the second pressure is detected at the pressure sensor. 
     
     
         13 . The method of  claim 10 , wherein comparing the second water condition to the first water condition comprises determining the second water condition is less than a variable threshold relative to the first water condition. 
     
     
         14 . The method of  claim 10 , wherein directing the drain pump comprises reactivating the drain pump. 
     
     
         15 . The method of  claim 14 , wherein reactivating the drain pump is for a reactivation period. 
     
     
         16 . The method of  claim 15 , wherein the reactivation period is limited to a predetermined time period for reactivation, and wherein the method further comprises deactivating, again, the drain pump in response to expiration of the predetermined time period for reactivation. 
     
     
         17 . The method of  claim 10 , further comprising:
 activating a circulation pump following reactivating the drain pump.   
     
     
         18 . The method of  claim 10 , further comprising:
 measuring expiration of a set period following detecting the first water condition,   wherein detecting the second water condition is in response to measuring expiration of the set period.