Dishwasher appliances generally include a tub that defines a wash compartment. Rack assemblies can be mounted within the wash compartment of the tub for receipt of articles for washing. Spray assemblies within the wash compartment can apply or direct wash fluid towards articles disposed within the rack assemblies in order to clean such articles. Multiple spray assemblies can be provided including e.g., a lower spray arm assembly mounted to the tub at a bottom of the wash compartment, a mid-level spray arm assembly mounted to one of the rack assemblies, and/or an upper spray assembly mounted to the tub at a top of the wash compartment. Other configurations may be used as well.
A dishwashing appliance is typically equipped with at least one pump for circulating wash fluid through the multiple spray assemblies during a wash or rinse cycle or discharging wash fluid from the dishwasher appliance during a drain cycle. During a wash cycle, the pump circulates the wash fluid through the multiple spray assemblies to clean articles placed within the wash compartment. The soiled wash fluid falls down and collects in a sump portion of the dishwasher appliance before being recirculated by the pump. As the wash cycle progresses and the wash fluid continues to circulate, the wash fluid becomes soiled and cleaning efficiency is decreased.
Notably, certain dishwasher appliances include a turbidity sensor for measuring the soil level of wash fluid being circulated through the dishwasher appliance. When the soil level of the wash fluid (e.g., as measured by the turbidity sensor) exceeds a certain threshold, the dishwasher appliance may initiate a full or partial drain cycle. In this manner, heavily soiled wash fluid may be discharged and the dishwasher appliance may be replenished with fresh wash fluid if another wash or rinse cycle is needed.
During a drain cycle, the pump will operate to discharge wash fluid for a predetermined amount of time. Notably, the time required to drain the wash fluid from a particular dishwasher appliance varies significantly depending upon a variety of factors. For example, the height of the discharge drain in the room where the dishwasher appliance is located may vary. In addition, clogged drains, inefficient pumps, variations in water valves, or other appliance variations can cause significant variation in the amount of time required to discharge all wash fluid in the sump.
Because the drain time is often fixed by the manufacturer, the fixed drain time is often selected to ensure full draining of the sump portion in the most demanding application. Therefore, in most applications, the actual drain time can be significantly less than the drain time fixed by the manufacturer. In this regard, the pump runs longer than necessary to ensure all of the wash fluid is discharged, resulting in wasted energy and increased noise levels which are disturbing to consumers.
Some dishwasher appliances might use a dedicated water level indicator to measure the level of water remaining in the sump portion of the dishwasher appliance. However, such water level indicators can add to the overall cost of producing the appliance, require time consuming and inconvenient calibration, result in a more complicated control system, and increase the likelihood of malfunction and required repair.
Accordingly, a dishwashing appliance that can be configured to operate a drain cycle for the minimal time needed to drain wash fluid from the sump would be useful. More particularly, a turbidity sensor that incorporates a water level indicator that may be used to determine the water level during a drain cycle and eliminate the need for an additional measuring device would be especially beneficial.