MRI Thermal Bus Structure for Faster Shield Heat Removal
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Solution Overview
Problem
Conventional magnetic resonance imaging devices face challenges in efficiently managing thermal energy transfer and mechanical support for their thermal shields, leading to high thermal resistance, slow heat removal, and temperature fluctuations that affect image quality and system stability.
Innovation Solution
A magnetic resonance imaging device with a thermal bus structure that includes a shield structure and thermal bus elements to reduce the length of thermal paths, enhance mechanical support, and improve heat removal efficiency, using materials like copper and aluminum for the thermal shield and bus elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the thermal shield is cooled via a cold head of a cryocooler with a thermal path around the superconducting magnet, then the thermal shield can be cooled, but the thermal resistance is high and the time constant for heat removal is long
Solution Approach 1:
The patent introduces a thermal bus structure that extends through the center of the superconducting magnet along the magnetic field direction, creating a new thermal conduction path through the third dimension (axial direction) rather than only around the magnet. This dimensional change reduces thermal path length and thermal resistance while maintaining effective heat removal from the thermal shield.
2Strength
If the thermal shield is made strong enough to bear forces during operation and quench events, then mechanical strength is sufficient, but material selection is complicated by multiple design constraints
Solution Approach 1:
The patent merges the thermal bus structure with the magnet support structure, creating a unified component that serves both thermal conduction and mechanical support functions. This integration reduces the number of separate components and simplifies material selection by consolidating design constraints into a single structure that can be optimized for both thermal and mechanical performance.
Solution Approach 2:
The thermal bus structure is designed to perform multiple functions simultaneously: it provides thermal conduction from the thermal shield to the cold head, supports the superconducting magnet mechanically, and maintains structural integrity during quench events. This multi-functionality reduces overall system complexity while meeting all design requirements.
3Use of energy by moving object
If the cryocooler operates in energy saving modes with reduced compressor speed, then energy consumption is reduced, but temperature fluctuations occur that affect image quality
Solution Approach 1:
The thermal bus structure acts as a thermal intermediary with high thermal conductivity that efficiently couples the thermal shield to the cold head. This improved thermal coupling reduces the thermal time constant, allowing the system to maintain temperature stability during partial-load operation and enabling energy-saving modes without sacrificing image quality through temperature fluctuations.
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 enhances heat removal rates, reduces material costs, allows for larger patient bores, and improves image quality by minimizing temperature fluctuations and mechanical deformations.
Implementation Method 1
a thermal bus structure (31) comprising a plurality of thermal bus elements (31i) arranged at non-perpendicular angles with respect to a direction of access of the object into the imaging region (36), wherein the plurality of thermal bus elements provides a thermal connection between the first stage (50) of the cold head (32a) and the shield structure (12)
Implementation Method 2
a shield structure (12) arranged between the gradient system (19) and the main magnet (17), wherein the shield structure reduces a transport of heat energy to the main magnet (17)
Implementation Method 3
a cryocooler (32) including a cold head (32a), wherein the first stage of the cold head is thermally connected to the shield structure via the thermal bus structure
Data Source
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AI summary
The invention relates to a magnetic resonance imaging device (11) comprising a main magnet (17), a gradient system (19) including at least one gradient coil, a thermal bus structure (31), a shield structure (12) arranged between the gradient system (19) and the main magnet (17) and a cryocooler (32) including a cold head, wherein the shield structure (12) is configured to reduce a transport of heat energy to the main magnet (17) and wherein the main magnet (17) comprises a magnet spacer configured for spacing individual coils of the main magnet (17), wherein the thermal bus structure (31) comprises at least one thermal bus element extending through the magnet spacer for providing a thermal connection between the cold head of the cryocooler (32) and the shield structure (12).