Ultrasonic Liquid Level Venting Layout for Bubble-Free Sensing
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Solution Overview
Problem
Conventional liquid level detecting devices in urea water tanks of construction machines are prone to inaccurate readings due to the ingress of air bubbles, which are generated by the sloshing of urea water during operation on uneven terrain, leading to reduced reliability in detecting the liquid level position.
Innovation Solution
A liquid level detecting device with a tubular case featuring a water flow hole covered by a porous film and a venting tube with external and internal venting holes, designed to prevent the ingress of air bubbles from the venting hole into the case, maintaining even pressure and allowing air exchange without obstructing the flow of urea water.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the air vent is covered with a porous membrane to prevent ingress of air bubbles, then the reliability of liquid level detection is improved, but the airflow resistance increases and the pressure balance is compromised
Solution Approach 1:
The air vent is divided into multiple separate vent holes instead of a single opening. This segmentation allows air to pass through multiple pathways while reducing the likelihood that liquid or air bubbles will block all pathways simultaneously, thereby maintaining airflow without requiring a porous membrane that would increase resistance
Solution Approach 2:
The vent holes are positioned at different locations and orientations on the air vent structure. By distributing the vent holes in different spatial dimensions, the system ensures that liquid sloshing in one direction will not block all vent pathways, maintaining air exchange capability while preventing liquid ingress
2Adaptability or versatility
If the urea water tank is operated on rugged and uneven land, then the construction machine's operational capability is improved, but air bubbles are generated and the liquid level detection accuracy deteriorates
Solution Approach 1:
Air bubbles are extracted or removed from the system by providing dedicated vent holes that allow air to escape from the urea water tank. The vent holes are strategically positioned to capture and vent air bubbles before they can interfere with the liquid level detection process, thereby maintaining detection accuracy during operation on rugged terrain
Solution Approach 2:
The air vent with multiple vent holes provides preliminary action by preventing air bubbles from accumulating in the first place. The vent holes are positioned to intercept air bubbles early in their formation and progression, preventing them from reaching the liquid level sensor and causing detection errors
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
The device effectively prevents air bubbles from entering the detection area, ensuring accurate liquid level detection by maintaining consistent pressure and airflow, thereby enhancing the reliability of the detection process.
Implementation Method 1
an ultrasonic sensor provided underneath the housing and detecting a liquid level position by reflecting ultrasound oscillating upward off a liquid level of urea water
Data Source
AI summary
A liquid level detecting device (21) includes a venting tube (27) located on an upper side (other side) of a case (22) opposite a water flow hole (25) and an ultrasonic sensor (23) and provided so as to penetrate a side surface portion (22A) of the case (22). In addition, the venting tube (27) is provided with external venting holes (28) that are open outward of the case (22) and an internal venting hole (29) that is open on the upper side (other side) of the case (22) within the case (22) and in communication with the external venting holes (28).