Rotating Clutch Piston Pressure Balancing Against Auto-Actuation
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Solution Overview
Problem
Existing transmission systems for aircraft low spool turbomachines face issues with auto-actuation of the rotating hydraulically actuated control piston, leading to unintended engagement of clutches, which is typically addressed by using large springs that increase weight and size.
Innovation Solution
A clutch assembly with a rotating control piston that modulates between disengaged and engaged positions via hydraulic pressure in a control pressure chamber and a pressure balancing chamber, filled with fluid, and includes orifices for fluid entry and exit, along with glide rings and a chamber divider connected to the output shaft, to prevent auto-actuation by balancing fluid pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If large springs are used to prevent control piston auto-actuation, then reliability is improved, but weight and device complexity increase
Solution Approach 1:
The patent applies hydraulic pressure balancing through a pressure balancing chamber filled with hydraulic fluid. The chamber is divided into a control pressure chamber and a pressure balancing chamber by a chamber divider. Hydraulic pressure in both chambers counteracts centrifugal forces that cause auto-actuation, eliminating the need for heavy mechanical springs while maintaining reliability.
Solution Approach 2:
The patent changes the physical state and pressure parameters of hydraulic fluid in the balancing chamber to counteract the centrifugal forces. By modulating hydraulic pressure in the control pressure chamber relative to the pressure balancing chamber, the system prevents piston auto-actuation without requiring large mechanical springs.
2Reliability
If large springs are used to prevent control piston auto-actuation, then reliability is improved, but device complexity and size increase
Solution Approach 1:
The patent replaces complex mechanical spring assemblies with a hydraulic pressure balancing system. The chamber divider creates two separate hydraulic chambers that work together to balance pressures, providing a more compact and less complex solution than traditional spring-based auto-actuation prevention mechanisms.
3Measurement precision
If hydraulic pressure modulation is used to control piston movement, then precision control is improved, but sensitivity to pressure fluctuations increases
Solution Approach 1:
The pressure balancing chamber acts as a counterbalance to the control pressure chamber. By maintaining equal hydraulic pressure in both chambers, the system counteracts the effects of pressure fluctuations and centrifugal forces, preventing auto-actuation while allowing precise control through controlled pressure differentials.
Solution Approach 2:
The dual-chamber hydraulic system with pressure balancing provides inherent stability against pressure-induced auto-actuation. The chamber divider separates the control function from the balancing function, allowing precise control through the control pressure chamber while the pressure balancing chamber compensates for pressure variations and centrifugal effects.
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 solution effectively reduces the incidence of unintentional clutch engagement by balancing fluid pressures, eliminating the need for large springs, thus reducing weight and size while maintaining precise control over gear ratio selection.
Implementation Method 1
The control piston is moved between a disengaged position and an engaged position via modulation of hydraulic pressure in the control pressure chamber
Implementation Method 2
the control piston is subject to inadvertently auto-actuating... large springs are used to prevent this auto-actuation problem... pressure balancing chamber filled with hydraulic fluid
Implementation Method 3
one or more glide rings positioned between the chamber divider and a radially outer wall of the piston member
Data Source
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AI summary
A clutch assembly includes a clutch pack (50), and a rotating control piston (48) selectably engageable with the clutch pack (50) via movement of the clutch piston along an axis of rotation of the control piston (48). The clutch piston includes a piston member (54) engageable with the clutch pack (50), a cover plate (58) installed into the piston member (54) to define an enclosed volume, and an axially fixed chamber divider (72) positioned in the enclosed volume to divide the enclosed volume into a control pressure chamber and a pressure balancing chamber. Both the control pressure chamber and the pressure balancing chamber are filled with hydraulic fluid, and the control piston (48) is moved between a disengaged position and an engaged position via modulation of hydraulic pressure in the control pressure chamber.