Systems and methods for failure detection of a pressure sensor in washing machine appliances
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Solution Overview
Problem
Existing washing machine appliances lack effective methods to accurately detect failures in pressure sensors, which can lead to improper operation due to incorrect fluid level detection.
Innovation Solution
Implementing a system with a turbidity sensor, conductivity sensor, and temperature sensor, along with a controller, to monitor and compare measurements against reference values to determine the presence or absence of fluid in the wash tub, thereby detecting pressure sensor failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pressure sensor is used to detect fluid level in the wash tub, then the washing machine can operate in various cycles with fluid handling, but the pressure sensor may fail without detection leading to improper operation
Solution Approach 1:
The system continuously monitors pressure sensor readings and compares them against expected values for different wash tub conditions (empty, partially full, full). When the pressure sensor reading deviates from expected values, the controller triggers verification using alternative detection methods, creating a feedback loop that ensures accurate fluid level detection even when the pressure sensor fails
Solution Approach 2:
The controller is pre-programmed with expected pressure sensor readings for various fluid levels and wash cycle conditions. Before relying on pressure sensor data for critical operations, the system performs preliminary checks to verify readings fall within expected ranges, and prepares alternative detection methods in advance to validate fluid presence if pressure sensor failure is detected
2Measurement precision
If multiple sensors are implemented to detect pressure sensor failure, then detection accuracy improves, but device complexity increases
Solution Approach 1:
The existing pressure sensor serves dual purposes: it continues to provide primary fluid level information for wash cycle control while simultaneously acting as part of the failure detection system. The controller uses the same pressure sensor readings to both monitor fluid levels and verify sensor functionality by comparing readings against expected values, eliminating the need for separate dedicated failure detection sensors
Solution Approach 2:
The pressure sensor system performs self-verification through the controller's analysis of reading patterns and consistency. The system monitors its own operational integrity by checking whether pressure sensor outputs align with expected physical conditions, allowing the washing machine to detect sensor failures without requiring external monitoring equipment
Data Source
AI summary
A controller is in signal communication with a pressure sensor, a turbidity sensor, a conductivity sensor and a temperature sensor. The controller is configured to monitor the pressure measurement of the pressure sensor and record an ambient temperature measurement in response to the pressure measurement stabilizing. The controller is also configured to record a turbidity measurement from the turbidity sensor, a conductivity measurement from the conductivity sensor, and a temperature measurement from the temperature sensor in response to the pressure measurement incrementing. Additionally, the controller is configured to compare the turbidity measurement to a reference turbidity value, the conductivity measurement to a reference conductivity value, and the temperature measurement to the ambient temperature measurement, and determine either a presence or an absence of fluid in the wash tub based at least in part on the turbidity measurement, the conductivity measurement, and the temperature measurement.