Pump inlet assemblies for dishwasher appliances

Abstract

A pump inlet assembly and method of operating a dishwasher appliance are provided. The pump inlet assembly includes an inlet conduit providing fluid communication between a sump and a pump. The inlet conduit defines an integrally formed boss which is coupled with a sensor housing using an overmolding process. A pressure sensor is positioned in the sensor housing and is protected from wash fluid by an airgap defined by the boss. The measured pressure may be used to determine the water level within the dishwasher when the pump is not operating and the suction pressure within the inlet conduit when the pump is operating. The inlet conduit, boss, pressure sensor, and pump housing may be integrally formed by injection molding and/or overmolding processes to reduce costs and the likelihood of leaks.

What is claimed is: 
     
         1 . A dishwasher appliance defining a vertical direction, the dishwasher appliance comprising:
 a wash tub that defines a wash chamber;   a pump for circulating a flow of wash fluid for cleaning articles placed within the wash chamber;   a sump positioned below the wash chamber along the vertical direction, the sump being configured for collecting wash fluid; and   a pump inlet assembly comprising:
 an inlet conduit providing fluid communication between the sump and the pump; 
 a pressure sensor for measuring a pressure of the wash fluid in the inlet conduit; 
 a boss integrally molded with the inlet conduit, the boss defining an airgap; and 
 a sensor housing coupled to the boss above the airgap using an overmolding process, the sensor housing being configured for receiving the pressure sensor. 
   
     
     
         2 . The dishwasher appliance of  claim 1 , wherein the sensor housing is formed by injection molding, and wherein the inlet conduit and the boss are overmolded directly to the sensor housing. 
     
     
         3 . The dishwasher appliance of  claim 1 , wherein the inlet conduit is coupled to the sump proximate a bottom of the sump. 
     
     
         4 . The dishwasher appliance of  claim 1 , wherein the inlet conduit is positioned and oriented such that the boss is disposed at an uppermost position along the vertical direction. 
     
     
         5 . The dishwasher appliance of  claim 1 , further comprising a controller in operative communication with a fluid inlet for controlling a flow of water into the wash chamber and the pressure sensor,
 wherein the pressure sensor measures the pressure of the wash fluid when the pump is not operating and the controller determines a fluid level within the wash chamber based on the pressure measurement.   
     
     
         6 . The dishwasher appliance of  claim 5 , wherein the controller is configured for stopping the flow of water from the fluid inlet when the measured fluid level reaches a predetermined threshold. 
     
     
         7 . The dishwasher appliance of  claim 1 , further comprising a controller in operative communication with a fluid inlet for controlling a flow of water into the wash chamber and the pressure sensor,
 wherein the pressure sensor measures the pressure of the wash fluid when the pump is operating and the controller determines a suction pressure of the pump based on the pressure measurement.   
     
     
         8 . The dishwasher appliance of  claim 7 , wherein the controller is configured for the flow of water from the fluid inlet after the measured suction pressure stabilizes at a predetermined threshold. 
     
     
         9 . A method of manufacturing a fluid circulation assembly of a dishwasher appliance, the dishwasher appliance comprising a pump for circulating a flow of wash fluid for cleaning articles placed within a wash chamber and a sump positioned below the wash chamber for collecting wash fluid, the method comprising:
 providing a sensor housing configured for receiving a pressure sensor;   overmolding an inlet conduit onto the sensor housing, the inlet conduit being coupled to the sensor housing by an integral boss which defines an airgap;   positioning the inlet conduit to establish fluid communication between the sump and the pump; and   positioning the pressure sensor in the sensor housing for measuring a pressure of the wash fluid in the inlet conduit.   
     
     
         10 . The method of  claim 9 , wherein the pressure sensor measures the pressure of the wash fluid when the pump is not operating to determine a fluid level within the wash chamber. 
     
     
         11 . The method of  claim 9 , wherein the pressure sensor measures the pressure of the wash fluid when the pump is operating to determine a suction pressure of the pump. 
     
     
         12 . The method of  claim 9 , wherein positioning the inlet conduit to establish fluid communication between the sump and the pump comprises overmolding the inlet conduit to a pump housing. 
     
     
         13 . A method of operating a dishwasher appliance, the dishwasher appliance comprising a pump for circulating a flow of wash fluid for cleaning articles placed within a wash chamber and a sump positioned below the wash chamber for collecting wash fluid, the method comprising:
 measuring the pressure of wash fluid in an inlet conduit which provides fluid communication between the sump and the pump, a sensor housing being formed integrally with the inlet conduit and being configured for receiving a pressure sensor; and   determining whether the pump is operating based on the pressure measurement from the pressure sensor.   
     
     
         14 . The method of  claim 13 , further comprising determining a fluid level within the sump based on the measured pressure of the wash fluid when the pump is not operating. 
     
     
         15 . The method of  claim 14 , further comprising:
 determining that the fluid level within the sump has exceeded a predetermined threshold; and   initiating an action in response to determining that the fluid level has exceeded the predetermined threshold.   
     
     
         16 . The method of  claim 15 , wherein the predetermined threshold is a maximum fluid level of the dishwasher and the initiated action is shutting off a flow of fluid into the dishwasher. 
     
     
         17 . The method of  claim 15 , wherein the predetermined threshold is a desired fill amount for an operating cycle of the dishwasher and the initiated action is shutting off a flow of fluid into the dishwasher and starting the operating cycle. 
     
     
         18 . The method of  claim 13 , further comprising determining a suction pressure of the pump based on the measured suction pressure of the wash fluid when the pump is operating. 
     
     
         19 . The method of  claim 18 , further comprising:
 determining that the measured suction pressure is unstable; and   initiating an action based on the determination that the measured suction pressure is unstable.   
     
     
         20 . The method of  claim 19 , wherein the measured suction pressure is unstable if the measured suction pressure falls below a low pressure threshold or varies beyond a variability limit, and
 wherein the initiated action is adding fluid to the dishwasher until the measured suction pressure stabilizes.