Ultrasonic Fill Level Sensor Foam Barrier Design
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Solution Overview
Problem
Devices for measuring the fill level of liquids in containers using ultrasonic sensors face challenges in accurately determining oil levels in running engines due to foam interference, as gas bubbles disrupt the reflection of ultrasonic waves, requiring effective protection against oil foam ingress.
Innovation Solution
The device incorporates a cover with inner and outer ventilation holes and strategically positioned screens that extend from the measuring tube to the cover's side wall, trapping air bubbles and creating a barrier against oil foam, enhancing stability and preventing foam penetration, even when the vehicle is inclined.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If ventilation holes are provided in the cover to allow liquid to rise and fall in the measuring tube, then the ease of operation is improved, but oil foam can enter through the ventilation holes and interfere with measurements
Solution Approach 1:
Screens are introduced as intermediary elements between the inner and outer ventilation holes. These screens act as mediators that allow air passage while blocking oil foam from entering the measuring tube, thus resolving the contradiction between maintaining ventilation functionality and preventing harmful foam ingress.
Solution Approach 2:
The screens are positioned specifically at critical locations within the cover structure where oil foam could potentially enter through ventilation holes. By applying the screen barrier locally at these vulnerable points rather than throughout the entire device, the solution maintains operational ease while providing targeted protection against foam interference.
2Reliability
If screens are added to block oil foam from entering the measuring tube, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The cover structure is segmented into functional zones with screens positioned only where needed to block foam while maintaining ventilation. This segmentation approach allows the device to achieve improved reliability through targeted foam blocking without adding complex structures throughout the entire device, thus managing device complexity effectively.
3Measurement precision
If multiple screens are provided to trap air bubbles and block foam, then the measurement precision is improved, but the manufacturing complexity increases
Solution Approach 1:
The screens serve multiple functions simultaneously: they block oil foam from entering the measuring tube, trap air bubbles to maintain a clear liquid column, and allow ventilation through their mesh structure. This multi-functionality enables the device to achieve improved measurement precision without proportionally increasing manufacturing complexity, as a single component design accomplishes multiple protective functions.
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 configuration effectively prevents oil foam from entering the measuring tube, providing stable and accurate fill level measurements by trapping air bubbles and allowing foam to drain, thus ensuring reliable operation under various conditions.
Implementation Method 1
ultrasonic waves are emitted from the bottom of the device and reflected at the phase boundary between the oil and the air above it to be received by the ultrasonic sensor again
Implementation Method 2
at least four screens are provided between the one or more inner ventilation holes and the one or more outer ventilation holes, so that when the device is operating at least two air bubbles are trapped in the region of the screens
Data Source
AI summary
A device for measuring a fill level of a liquid in a container with an ultrasonic sensor, wherein the ultrasonic sensor is arranged at the bottom end of a damping cup with a measuring tube, wherein the top area of the measuring tube has at least one inner ventilation hole and a cover assigned to the inner ventilation hole. The cover surrounds at least the upper end area of the measuring tube and itself has at least one outer ventilation hole, wherein at least one screen is present in the cover and is in contact with the cover at the top. The screen is in contact with the cover at the top and extends horizontally from the measuring tube as far as a side wall of the cover.