Membrane Air Dryer with Dynamic Sweep Control
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Solution Overview
Problem
Membrane air dryers for locomotives face challenges such as high ambient temperatures, environmental hazards, and inefficiencies due to constant sweep air flow, which wastes air and depletes reservoir pressure, especially when the locomotive is idled.
Innovation Solution
A membrane air dryer design that includes a housing with concentric sweep air passages, a solenoid-controlled drain valve, and a brake controller to manage sweep air flow dynamically, ensuring air is only consumed when needed, and maintaining dry air in the reservoir by controlling the sweep air flow based on brake system usage and compressor status.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If constant sweep air flow is used to maintain dry air and pressure differential across the membrane, then the membrane drying function is ensured, but air is wasted and reservoir pressure is depleted
Solution Approach 1:
The patent applies dynamics by transitioning from constant sweep air flow to variable sweep air flow controlled by a controller that responds to brake system conditions. The controller dynamically adjusts the sweep air valve opening based on reservoir pressure, brake application status, and compressor operation, ensuring the membrane functions reliably only when needed while minimizing air waste during idle periods.
Solution Approach 2:
The patent implements feedback through a control system that continuously monitors reservoir pressure, brake application status, and compressor operation. This feedback loop adjusts the sweep air flow rate accordingly - maintaining sufficient flow to keep the membrane dry when brakes are applied, and reducing or stopping flow when brakes are not applied, thereby preventing air waste while ensuring reliable drying function when needed.
2Stress or pressure
If sweep air orifices are used to control sweep air volume and create pressure drop, then the membrane pressure differential is maintained, but the system complexity increases with fixed orifice design
Solution Approach 1:
The patent replaces fixed sweep air orifices with a dynamic control system using a controllable valve (such as a solenoid valve or proportional valve) managed by a controller. This allows the sweep air flow rate and pressure differential to be dynamically adjusted based on actual brake system conditions, reducing device complexity by eliminating fixed restrictive orifices while maintaining or improving pressure control effectiveness.
Solution Approach 2:
The patent changes the control parameter from fixed orifice geometry to variable valve opening controlled by electrical signals. The controller adjusts the sweep air flow parameters (flow rate, pressure) based on brake application status and reservoir pressure conditions, providing flexible control without the complexity of precisely engineered fixed orifices.
3Volume of moving object
If the membrane air dryer is packaged inside the reservoir with pre-filter, then space is saved and weight is minimized, but the membrane is exposed to high ambient temperatures and environmental hazards
Solution Approach 1:
The patent applies nesting by placing the membrane air dryer assembly inside the reservoir, utilizing the existing reservoir space. The pre-filter is positioned at the reservoir inlet, the membrane element is housed within the reservoir volume, and the sweep air passages utilize the annular space between the membrane and reservoir wall, thereby minimizing installation space while protecting the membrane from environmental hazards through the reservoir housing.
Solution Approach 2:
The patent provides thermal protection by positioning the membrane air dryer inside the reservoir, which serves as a protective housing shielding the membrane from high ambient temperatures and environmental hazards such as flying stone ballast. The reservoir acts as a cushioning barrier before harmful factors can reach the sensitive membrane element.
4Reliability
If sweep air is provided continuously to maintain membrane dryness, then the membrane remains effective, but reservoir pressure is depleted during locomotive idle periods
Solution Approach 1:
The patent implements periodic action by controlling sweep air flow to operate only during brake application periods rather than continuously. The controller activates the sweep air valve when brake application is detected and deactivates it when brakes are not applied, providing periodic rather than continuous sweep air flow. This maintains membrane effectiveness during brake use while preserving reservoir air quantity during idle periods.
Solution Approach 2:
The patent applies dynamics by making sweep air flow conditional and variable rather than constant. The controller dynamically adjusts sweep air flow based on brake system status, providing sufficient flow to maintain membrane dryness during brake applications and reducing or stopping flow during idle periods, thereby balancing membrane effectiveness with reservoir air conservation.
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 design minimizes weight, protects the membrane from extreme temperatures, eliminates installation piping, and optimizes air usage by only consuming sweep air when necessary, reducing waste and ensuring efficient drying of air in the locomotive's brake system.
Implementation Method 1
membranes consisting of a permeable membrane capable of blocking the passage of nitrogen and oxygen molecules, but allowing water vapor molecules to pass through
Implementation Method 2
creating the partial pressure differential to drive the water vapor out
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The membrane (40) air dryer includes a housing (44) with an air inlet (46) adjacent a first end of the housing, an air outlet (48) adjacent a second end of the housing, a sweep air inlet (51) and a sweep air outlet (54). A first sweep air passage in the housing extends between the first and second ends of the membrane along. The surfaces of the membrane. The first sweep air passage has an inlet adjacent the air outlet and an outlet adjacent the air inlet and connected to the sweep air outlet. The sweep air inlet and outlet is adjacent the air inlet. A second sweep air passage extends between the first and second ends of the membrane. The second sweep air passage has an inlet (140) that is connected to the sweep air inlet and is adjacent the air inlet and has an outlet (154) that is adjacent the air outlet and in fluid communication with the inlet of the first sweep air passage. The membrane air dryer is mounted to extend into the reservoir (26).