Filter Device for CTIS Air Supply Integrity
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Solution Overview
Problem
Central tyre inflation systems (CTIS) face issues with air leaks into the CV joint enclosure due to the ingress of compressed air, which is not effectively addressed by vented gaiters, and existing solutions do not adequately prevent the entry of lubricants into the air supply lines within vehicle axles.
Innovation Solution
A filter device comprising a gas-permeable pre-filter element and a gas-permeable, liquid-impermeable filter element is fluidly coupled to the conduit, allowing gas to flow while preventing liquids from entering, using materials like porous foam and oleophobic membranes to inhibit liquid ingress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If vented gaiters are used to equalise pressure, then air leakage is reduced, but the gaiters can become obstructed and venting efficiency deteriorates
Solution Approach 1:
A filter device is introduced as an intermediary component between the CV joint enclosure and the external environment. This filter device includes a gas-permeable pre-filter element and a gas-permeable liquid-impermeable filter element that selectively allow gas to pass while blocking liquids, thereby maintaining pressure equalisation without obstruction from lubricants
Solution Approach 2:
The filter device utilizes porous materials with specific permeability characteristics. The pre-filter element is gas-permeable to allow air flow, while the liquid-impermeable filter element has pore structures that permit gas molecules to pass but block larger liquid molecules, enabling selective filtration
2Reliability
If the gaiter is sealed to prevent air leakage, then air supply efficiency is improved, but lubricants can ingress into the air supply lines
Solution Approach 1:
The filter device serves as an intermediary barrier at the conduit entrance, allowing air to pass through to maintain air supply integrity while simultaneously blocking lubricants from entering the air supply lines and contaminating internal components
Solution Approach 2:
The filter device provides localized protection at the critical interface where the conduit enters the CV joint enclosure. The different layers of the filter (gas-permeable pre-filter and gas-permeable liquid-impermeable element) have different local properties that together achieve both air flow and liquid blocking 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
The filter device effectively prevents liquid ingress into the conduit, ensuring that compressed air can flow through the system without contamination, maintaining the integrity of the air supply and protecting internal components from lubricants like grease or oil.
Implementation Method 1
a gas-permeable pre-filter element
Implementation Method 2
a gas-permeable, liquid-impermeable filter element
Data Source
AI summary
A filter device for a conduit includes a gas-permeable pre-filter element and a gas-permeable, liquid-impermeable filter element. The filter device is configured to be fluidly coupled to a conduit such that a gas can flow, in sequence, through the pre-filter element, the filter element and then the conduit. The filter device can be used in each of a vehicle hollow driveshaft and a hollow wheel stub axle forming a CV joint having a compressed air supply line which passes therethrough. Compressed air can be supplied via the air supply line without the need for an additional fluid transfer device fluidly connecting the driveshaft and the stub axle's conduits.