Ultrasonic Coolant Level Sensor With Vertical Standpipe
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Solution Overview
Problem
Existing methods for estimating coolant levels in a coolant reservoir are inaccurate due to variations in reservoir dimensions with temperature and the location of ultrasonic sensors, which can lead to unclear low coolant levels and difficulties in differentiating between actual low levels and sensor degradation, especially when coolant is isolated in the power train.
Innovation Solution
A method involving a vertical, hollow standpipe fluidically coupled to the coolant overflow reservoir, equipped with an ultrasonic sensor, where the sensor estimates the coolant level based on echo times and compensates for changes due to vehicle motion, ensuring accurate coolant level inference by accounting for slosh and fluid transfer between the standpipe and reservoir.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an ultrasonic sensor is installed at the bottom of the coolant reservoir to estimate fluid level, then the coolant level can be detected, but the estimation becomes inaccurate due to thermal expansion of the reservoir dimensions and difficulty in distinguishing low coolant levels from sensor degradation
Solution Approach 1:
A vertical standpipe is introduced as an intermediary component between the coolant reservoir and the ultrasonic sensor. The standpipe provides a controlled, narrow measurement chamber where coolant level can be accurately detected. The standpipe is fluidically coupled to the reservoir, allowing coolant to rise into it, but isolates the sensor from the thermal expansion issues of the main reservoir. This intermediary structure enables reliable distinction between actual low coolant levels and sensor degradation.
2Temperature
If the coolant reservoir dimensions vary with temperature, then thermal expansion occurs, but this causes inconsistencies in the estimated coolant level
Solution Approach 1:
The coolant level measurement system is segmented into two distinct parts: the main coolant reservoir and a separate vertical standpipe. The standpipe is a narrow, isolated chamber that contains the ultrasonic sensor. By segmenting the measurement function from the storage function, the system eliminates the problem of thermal expansion affecting the measurement chamber dimensions. The standpipe's narrow cross-section and isolated position minimize thermal effects, providing consistent measurement reference.
3Measurement precision
If the sensor is located at the bottom of the container, then coolant level can be measured, but at low coolant levels it becomes unclear whether the fluid level is low or empty
Solution Approach 1:
The standpipe creates a localized measurement zone with distinct physical characteristics from the main reservoir. The narrow diameter and vertical orientation of the standpipe create a clearly defined coolant-air interface that is easily detectable by the ultrasonic sensor. This localized structure ensures that even at low coolant levels, the meniscus in the standpipe remains clearly visible and measurable, eliminating the ambiguity present in the larger reservoir.
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 approach enhances the accuracy and reliability of coolant level estimation, reducing engine overheating by accurately determining coolant levels and compensating for errors caused by thermal fluctuations and vehicle motion, thereby preventing false low readings and improving engine performance.
Implementation Method 1
an ultrasonic sensor... transmits a signal to the top of the vertical tube, an echo of the signal being received at the sensor after being reflected off the top of the tube
Data Source
AI summary
Methods and systems are providing for improving engine coolant level estimation to reduce engine overheating. The level of fluid in a coolant overflow reservoir is inferred based on the fluid level in a hollow vertical standpipe fluidically coupled to the reservoir at top and bottom locations, while the fluid level in the standpipe is estimated based on echo times of an ultrasonic signal transmitted by a sensor positioned in a recess at the bottom of the vertical standpipe. Sensor output is compensated with a term based on vehicle motion parameters to compensate for fluid level distortion due to motion-induced slosh.