Cryogenic Plate Positioning With Switchable Indexing
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Solution Overview
Problem
Existing rotational positioning systems fail to operate effectively at very low temperatures and in vacuum conditions due to manufacturing limitations and unsuitability, leading to issues such as decreased belt length, increased tension, stiffness, and potential breakage, as well as the use of bulky and expensive pancake-type stepper motors with limited angular resolution.
Innovation Solution
A positioning system incorporating a plate with a motor, an indexing system, and a reducer with angular backlash, where the indexing system is deactivated during motor operation, allowing precise movement and maintenance of position without negative feedback, and utilizing conventional stepper motors with a solid shaft for reduced costs and increased positioning precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a toothed belt is used for positioning at room temperature, then positioning can be achieved, but at very low temperatures the belt length decreases and tension increases causing the device to become unusable
Solution Approach 1:
The patent replaces the toothed belt transmission with a direct drive system where the motor shaft is directly coupled to the positioning stage. This eliminates the intermediate transmission elements (belt, pulleys) that are sensitive to temperature changes, allowing reliable operation from -250°C to +70°C without the dimensional changes and tension variations that plague belt-driven systems at cryogenic temperatures
Solution Approach 2:
The patent removes the toothed belt and pulley system from the design, extracting the problematic temperature-sensitive components. By using direct motor-to-stage coupling, the system eliminates the transmission chain that causes failure at low temperatures, while maintaining positioning capability through the motor's own resolution and the indexing system
2Reliability
If a pancake-type stepper motor with hollow shaft is used, then cryogenic operation is possible, but the motor becomes bulky and expensive with limited angular resolution
Solution Approach 1:
The patent uses conventional, inexpensive stepper motors with solid shafts instead of specialized cryogenic motors. While conventional motors aren't designed for cryogenic operation, the patent compensates by using materials with similar thermal expansion coefficients and implementing an indexing system, thereby achieving cryogenic compatibility through system-level design rather than requiring expensive specialized components
Solution Approach 2:
The patent makes the indexing system serve multiple functions: it provides precise positioning, maintains position during motor deactivation, compensates for thermal expansion differences, and enables operation with conventional motors. This multi-functional indexing mechanism allows the system to achieve cryogenic compatibility without specialized motors, reducing cost and complexity
3Manufacturing precision
If a gearbox with clearance-free assembly is used to achieve good positioning performance, then positioning precision improves, but the system becomes unsuitable for very low temperatures
Solution Approach 1:
The patent changes the transmission approach from precision gearbox with clearance-free assembly to direct drive with indexing. The indexing system provides the necessary positioning precision through discrete position locking, eliminating the need for complex precision gearboxes that are sensitive to thermal contraction at low temperatures
Solution Approach 2:
The patent segments the positioning function into two independent parts: the motor provides motion capability, while the indexing system provides precision positioning and holding. This segmentation allows each component to be optimized independently - the motor can be a simple conventional type, while the indexing system handles the precision requirements without being temperature-sensitive
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 system achieves high positioning precision and speed, with the ability to operate across a wide temperature range (-250°C to +70°C) and in vacuum conditions, while maintaining discrete positioning and reducing production costs by using conventional stepper motors and materials with similar expansion coefficients.
Implementation Method 1
a return means arranged under the plate, having an elastic nature, so as to exert a restoring force on the plate in the direction of the crown
Implementation Method 2
an electromagnet ensuring the distance of the plate relative to the crown
Data Source
Figure 1~2
Figure 3~5
AI summary
Positioning system comprising a frame (4) and a plate (2), said plate (2) being mounted movable relative to the frame, said plate (2) being able to support an object to be positioned, means for moving the plate relative to the frame to a desired position, and a position indexing system of the plate (2) relative to the frame, the movement means comprising a stepper motor (6) and a reducer (8), said reducer (8) having angular backlash and the indexing system (18) comprising means for making the position indexing of said plate (2) inactive during the operation of the movement means.