Cryogenic Regulating Valve Rack-Pinion Clearance Adjustment
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Solution Overview
Problem
Cryogenic regulation valves in aeronautical and astronautical engines, such as rocket engines, face challenges in precision due to functional play in mechanisms like the Pable-Crémaillère transmission system, which can be affected by temperature variations leading to dimensional changes and impacting the valve's precision and robustness.
Innovation Solution
A cryogenic regulation valve with a gable/rack transmission system that includes an annular bonding flange allowing for precise adjustment of the rack's position relative to the gable, using a rotation mechanism to minimize functional play and maintain lineic contact, thereby improving precision and robustness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the rack and pinion transmission system uses fixed clearances, then the manufacturing is simpler, but the valve precision deteriorates due to functional play affecting accuracy
Solution Approach 1:
The patent applies the dynamics principle by making the clearance in the rack and pinion transmission system adjustable rather than fixed. The adjustment mechanism allows the clearance to be modified based on operating conditions, particularly temperature variations. This resolves the contradiction by enabling precise valve operation through dynamic clearance adjustment while maintaining a relatively simple transmission system structure.
Solution Approach 2:
The patent applies the parameter changes principle by allowing the clearance parameter in the transmission system to be changed according to operating conditions. The adjustment mechanism modifies the physical clearance between rack and pinion teeth, optimizing the Hertzian pressure contact and minimizing functional play. This enables precise valve operation across different temperature ranges without requiring a completely complex transmission system design.
2Manufacturing precision
If the clearance is reduced to minimize functional play, then the valve precision improves, but the risk of hyperstaticity and operational blocking increases
Solution Approach 1:
The patent applies the dynamics principle by implementing an adjustable clearance mechanism that allows the system to adapt between minimal clearance (for precision) and adequate clearance (for reliability). The adjustment mechanism ensures that the clearance never becomes zero, preventing hyperstaticity and operational blocking while maintaining sufficient precision for valve operation. This dynamic adjustment resolves the contradiction between precision and reliability.
Solution Approach 2:
The patent applies the preliminary anti-action principle by pre-configuring the adjustment mechanism to prevent hyperstaticity before it occurs. The system is designed with built-in adjustment capabilities that allow operators to optimize clearance settings, preventing the conditions that would lead to operational blocking. This preliminary preparation ensures both precision and reliability are maintained.
3Strength
If the materials are selected for strength, then the structural integrity improves, but the differential thermal contraction increases causing play in the mechanism
Solution Approach 1:
The patent applies the parameter changes principle by making the clearance parameter adjustable to compensate for differential thermal contraction. As temperature changes cause different materials to contract or expand at different rates, the adjustment mechanism modifies the clearance to maintain optimal Hertzian pressure contact and minimize functional play. This resolves the contradiction by allowing strong structural materials to be used while maintaining mechanism precision through parameter adjustment.
Solution Approach 2:
The patent applies the thermal expansion principle by designing the adjustment mechanism to account for and compensate for differential thermal contraction of various materials. The system allows clearance adjustment based on temperature conditions, ensuring that thermal expansion and contraction of different materials do not create excessive play in the mechanism. This enables the use of strong structural materials while maintaining precision across the operating temperature range.
4Reliability
If the clearance is increased to avoid hyperstaticity, then the operational reliability improves, but the valve precision deteriorates due to excessive functional play
Solution Approach 1:
The patent applies the dynamics principle by implementing an adjustable clearance mechanism that allows the system to optimize the balance between reliability and precision. The adjustment mechanism enables the clearance to be minimized (improving precision) while maintaining sufficient gap to prevent hyperstaticity (maintaining reliability). This dynamic adjustment resolves the contradiction by allowing the system to operate in the optimal clearance range under different conditions.
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 enables precise adjustment of functional play, enhancing the precision and robustness of the valve operation while maintaining favorable Hertz pressure contact, even under varying temperatures.
Implementation Method 1
a rolling element arranged at least partly in the valve body, movable in translation along a second axis substantially perpendicular to the first axis, and comprising a rack, the rack being engaged with the pinion so that a rotation of the transmission shaft causes a translation of the rolling element
Implementation Method 2
a first end of the rolling element being guided in translation by a first fixed bearing
Implementation Method 3
a second end of the rolling element being guided in translation by a second bearing
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
Regulating valve (1) with rack/pinion transmission system for an aircraft or spacecraft, comprising a valve body (10), a transmission shaft (40), a throttling element (30), a rack (32) of the throttling element being engaged with a pinion (42) of the shaft (40), a first end of the throttling element being guided in translational movement by a first bearing (51), and a second end of the throttling element being guided in translational movement by a second bearing (52), the valve comprising an annular connecting flange (20) fixed to the valve body (10), the annular connecting flange (20) extending radially between an internal face (22) that exhibits symmetry of revolution about a second axis (X') of the throttling element (30) and an external face (24) that exhibits symmetry of revolution about a central axis (X), the internal face (22) comprising a radially internal housing (26) in which the second bearing (52) is housed, the second axis (X') being offset radially from the central axis (X).