Aircraft Brake Actuator Wear Compensation via Friction Stop
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Solution Overview
Problem
Aircraft hydraulic brake actuators require a simplified structure that maintains effective contact with friction elements despite wear, ensuring consistent braking performance without complex wear take-up devices.
Innovation Solution
A braking actuator with a simplified wear take-up device using a friction member that serves as both a movable stop and a support for an elastic return member, allowing the elastic member to compress and push the stop back when the piston's operational stroke is consumed, maintaining contact with friction elements and compensating for wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a traditional wear take-up device with a movable stop mounted on a central rod is used, then the piston can maintain contact with friction elements during wear, but the structure becomes more complex with additional components like the central rod and friction rings
Solution Approach 1:
The movable stop and friction member are merged into a single integrated component. The friction member directly contacts the sleeve wall and serves as the movable stop, eliminating the need for a separate central rod and friction rings. This integration maintains the wear compensation function while significantly simplifying the overall structure.
Solution Approach 2:
The central rod and friction rings are extracted/removed from the system. The invention achieves the same wear take-up function without these intermediate components by having the friction member act directly on the sleeve wall, reducing the number of parts and simplifying the mechanism.
2Device complexity
If the movable stop is reduced to a simple friction member, then the structure is simplified, but the elastic return member must generate sufficient force to push back the friction member when the piston stroke is consumed
Solution Approach 1:
The elastic member's force characteristics are optimized to provide sufficient return force. The spring is designed with appropriate stiffness and pre-compression to generate enough force to push the friction member back against friction resistance, ensuring reliable operation despite the simplified structure.
3Length of moving object
If the piston operational stroke is made sufficient for normal braking, then free rotor rotation is allowed, but the piston may not remain close to friction elements as friction elements wear out
Solution Approach 1:
The system dynamically adapts to wear through the friction member's movement. As friction elements wear and the gap increases, the piston extends further during braking, carrying the friction member along. The friction member progressively advances along the sleeve wall, automatically compensating for wear and maintaining optimal contact without requiring a longer initial piston stroke.
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, simplified structure that ensures consistent braking performance by advancing the retracted position of the piston to maintain contact with friction elements, effectively addressing wear-related issues without increasing complexity.
Implementation Method 1
an elastic member (16) towards the retracted position resting on the movable stop... the elastic member having during its compression an increase in force sufficient to be able to push back the movable stop
Implementation Method 2
the movable stop is reduced to a friction member rubbing against the liner, so that one of the faces of the friction member serves as a stop defining the retracted position of the piston
Implementation Method 3
the elastic member is an elastic spring whose turns can become contiguous under the force applied by the pressurized fluid. Thus compacted, the helical spring behaves like a non-deformable solid capable of pushing the mobile stop
Data Source
Figure 1~3
Figure 4~5
AI summary
The invention relates to a brake actuator for an aircraft hydraulic brake, intended to be brought into one of the cavities of a brake ring, the actuator comprising a sleeve (1) adapted to be received by sealing in the cavity of the ring, a piston (3) mounted to slide by sealing in the sleeve along a sliding axis (X) to apply a braking force on friction elements when a pressurized fluid is introduced into the cavity, and having a determined operating stroke, a wear compensation device (10) which defines a retraction position of the piston in the sleeve by means of a movable stop (11) which can be advanced by the piston when a braking force is applied, and an elastic element (16) for returning the piston to the retraction position bearing against the movable stop.According to the invention, the movable stop is reduced to a friction element rubbing against the sleeve, so that one of the faces of the friction element serves as a stop defining the retraction position of the piston, and the other of the faces serves as a support for the elastic return element, the elastic element presenting during its compression an increase of force sufficient to be able to push back the movable stop in the event that the piston does not touch the friction elements when its operational stroke has already been consumed.