Drain Pump Shutoff Using Current and Voltage Thresholds
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Solution Overview
Problem
Existing laundry treating appliances, such as clothes washers, face operational concerns due to pumps being unable to operate efficiently when there is insufficient liquid, leading to undesirable noise and potential motor damage, as they primarily rely on liquid presence to function.
Innovation Solution
A controller is used to monitor the change in electrical current and voltage supplied to the drain pump, allowing it to automatically shut off when specific thresholds are met, thereby preventing damage and noise by distinguishing between liquid and air pumping states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the drain pump operates continuously to drain liquid from the treating chamber, then the productivity is improved, but the pump may be damaged or generate noise when pumping air instead of liquid
Solution Approach 1:
The controller monitors electrical current and voltage parameters from the pump motor and uses this feedback to detect when the pump transitions from liquid pumping to air pumping. When the feedback indicates air pumping conditions (current drop below threshold, voltage change beyond threshold), the controller automatically shuts off the pump, preventing damage and noise while maintaining high productivity during actual drainage operations.
2Device complexity
If the pump operates without sufficient liquid, then the device complexity is reduced, but harmful factors are generated including noise and potential motor damage
Solution Approach 1:
The patent replaces complex mechanical liquid level detection systems with an electrical parameter monitoring system. The controller simply monitors current and voltage electrical parameters, compares them against predetermined thresholds, and controls the pump based on these electrical readings. This substitution maintains low device complexity while effectively preventing harmful factors by detecting air pumping conditions through electrical parameter changes.
3Reliability
If the pump is shut off automatically when liquid is insufficient, then the reliability is improved, but the productivity may be reduced due to premature shutdown
Solution Approach 1:
The controller monitors changes in electrical parameters (current and voltage) to detect the transition from liquid pumping to air pumping. By setting appropriate thresholds for current drop and voltage change, the system accurately identifies when liquid is depleted and shuts off the pump at the optimal moment. This parameter-based control ensures the pump operates at full productivity during actual drainage while shutting off reliably when liquid is insufficient, balancing both productivity and reliability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution effectively prevents pump damage and noise by accurately determining when to shut off the drain pump, ensuring efficient operation and extending the pump's lifespan.
Implementation Method 1
An operational concern with most liquid pumps is that the pump can only be operated when there is sufficient liquid to satisfy the pump, which prevents undesirable noise generated when a liquid pump is pumping substantial amounts of air and also reduces the likelihood of damaging the motor of the pump.
Implementation Method 2
A controller may be used to monitor the change in electrical current and voltage supplied to the pump. In this way, the controller can be used to turn off the pump when the change in electrical current supplied to the pump satisfies a first threshold and the change in the electrical voltage supplied to the pump satisfies a second threshold.
Data Source
AI summary
A laundry treating appliance having a pump, such as a drain pump, with an automatic shutoff, and a method for controlling the shut off of the pump.