Cryogenic Fluid Storage Unit With Bellows-Isolated High-Pressure Transfer
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Solution Overview
Problem
Existing cryogenic fluid storage units for vehicles face challenges with high internal pressures, leading to thick walls and significant mass, which is disadvantageous for on-board applications, and rely on unreliable piston pumps for high-pressure fluid injection, causing bearing seizure issues.
Innovation Solution
A cryogenic fluid storage unit with an internal reservoir, external reservoir separated by a low-pressure intermediate space, and a cryogenic fluid transfer member comprising a movable piston, motor, and mechanical transmission isolated by a bellows, which operates under vacuum to prevent bearing seizure and enhance reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If the storage unit is designed to withstand high internal pressures (above 27 bar), then the hydrogen injection pressure requirement is met, but the wall thickness becomes very thick and the mass becomes very significant
Solution Approach 1:
The storage unit is divided into two separate reservoirs (internal reservoir for cryogenic hydrogen and external reservoir for high-pressure hydrogen) connected by a transfer member. This segmentation allows the internal reservoir to operate at low pressure (1-27 bar) with thinner walls, while the external reservoir handles the high-pressure injection (40-200 bar) separately, thus reducing the overall mass while meeting pressure requirements.
2Stress or pressure
If piston pumps are used to increase the pressure of cryogenic fluid for injection, then the required high injection pressure (40-200 bar) is achieved, but the reliability becomes very low due to bearing seizure
Solution Approach 1:
A bellows is introduced as an intermediary element between the cryogenic fluid and the motor/transmission components. The bellows isolates the motor and mechanical transmission from direct contact with cryogenic hydrogen, preventing bearing seizure while still allowing the transfer of mechanical motion to drive the piston pump, thus achieving high injection pressure with improved reliability.
3Ease of operation
If the motor and mechanical transmission are exposed to cryogenic fluid, then direct drive is possible, but the bearings seize due to contact with hydrogen
Solution Approach 1:
The bellows serves as a mediator that transmits mechanical motion from the motor to the piston pump while preventing direct contact between the cryogenic hydrogen and the motor/transmission components. This allows direct drive functionality to be maintained while protecting the bearings from hydrogen exposure, ensuring long service life.
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 solution provides a compact and reliable cryogenic fluid storage unit capable of achieving high discharge pressures without piston wear, ensuring long service life and efficient fluid transfer to internal combustion engines.
Implementation Method 1
a bellows (47) isolating the motor (33) and the mechanical transmission (35) from the cryogenic fluid
Implementation Method 2
They are in contact with a vacuum prevailing in the low-pressure intermediate space
Data Source
AI summary
A storage unit comprises an internal reservoir and an external reservoir, where the internal reservoir and the external reservoir are separated from each other by an intermediate space. A cryogenic fluid transfer member is housed in the intermediate space, and the cryogenic fluid the transfer member comprises a body delimiting a chamber, an intake placing the chamber in communication with a cryogenic fluid storage volume delimited in the internal reservoir, a discharge, a movable member configured to move relative to the body by varying a volume of the chamber), a motor, and a mechanical transmission transmitting a movement from an output shaft of the motor to the movable member. The movable member is connected to the body by a bellows isolating the motor and the mechanical transmission from cryogenic fluid.