Fixed Wobbler with DLC Coating for Aircraft Hydraulic Units
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Solution Overview
Problem
Packaging constraints in aircraft integrated drive generators require redesigning components of the hydraulic unit, specifically the variable and fixed wobblers, to maintain constant generator speed despite varying engine rotational speeds.
Innovation Solution
A fixed wobbler design with a body having specific dimensions, an angled surface, a friction-reducing coating, and a locking feature, optimized to reduce size and weight while maintaining operational efficiency, is introduced. The fixed wobbler includes an Amorphous Diamond-like Carbon Coating and precise geometric features to enhance performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the fixed wobbler is redesigned to reduce size, then packaging constraints are satisfied, but manufacturing precision requirements increase due to tight tolerances
Solution Approach 1:
The patent applies parameter changes by optimizing the fixed wobbler's dimensional parameters within tight tolerance ranges. The outer diameter is specified as 2.1655±0.0007 inches and inner diameter as 1.043±0.003 inches, representing precise parameter control to achieve both size reduction and functional requirements. The angled surface parameter (12.75°-16.75°) is also optimized to maintain hydraulic unit efficiency while minimizing component size.
Solution Approach 2:
The patent employs composite materials by applying an Amorphous Diamond-like Carbon Coating to the fixed wobbler body. This coating reduces friction between the fixed wobbler and pistons, compensating for the reduced size and tight tolerances. The combination of the metal body substrate and diamond-like carbon coating creates a composite structure that achieves both compact dimensions and high manufacturing precision through reduced wear and friction.
2Volume of moving object
If the fixed wobbler size is reduced, then packaging constraints are satisfied, but the component weight decreases
Solution Approach 1:
The patent optimizes the fixed wobbler's geometric parameters to reduce both volume and weight simultaneously. By specifying precise dimensional parameters (outer diameter 2.1655±0.0007 inches, inner diameter 1.043±0.003 inches) and optimizing the angled surface configuration, the design achieves minimum material usage while maintaining structural integrity and functional performance in the reduced-size component.
Solution Approach 2:
The diamond-like carbon coating applied to the fixed wobbler provides a lightweight protective layer that reduces friction and wear without adding significant weight. This coating enables the use of optimized, reduced dimensions while maintaining the component's durability and performance, effectively decoupling weight reduction from strength compromise.
3Productivity
If tight dimensional tolerances are specified, then operational efficiency is maintained, but manufacturing complexity increases
Solution Approach 1:
The patent specifies optimized parameter ranges rather than fixed values where appropriate, such as the angled surface (12.75°-16.75°) and friction coating thickness (3-5 microns). This approach maintains hydraulic unit efficiency by ensuring parameters fall within performance-critical ranges while providing manufacturing flexibility, thereby reducing complexity compared to specifying exact fixed values for all dimensions.
Solution Approach 2:
The application of diamond-like carbon coating with specified thickness (3-5 microns) provides a standardized solution for friction reduction that simplifies manufacturing. Rather than requiring complex surface treatments or precision machining to achieve low friction, the coating process provides a repeatable, controlled method to maintain operational efficiency while simplifying the manufacturing workflow.
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 redesigned fixed wobbler effectively maintains constant rotational speed of the generator by adjusting to varying engine speeds, improving the hydraulic unit's efficiency and reliability within the packaging constraints of aircraft systems.
Implementation Method 1
The second surface comprises a friction-reducing coating; wherein the friction-reducing coating is between approximately 3 microns and approximately 5 microns; wherein the friction-reducing coating is an Amorphous Diamond-like Carbon Coating
Data Source
AI summary
A fixed wobbler of a hydraulic unit includes a body having a first end and an opposite second end, the first end defining a first surface, and the second end defining a second surface oriented at an angle relative to the first surface, the body having an outer diameter and an inner wall defining an inner diameter, wherein the outer diameter is approximately 2.1655+0.0000-0.0007 inches (5.5004+0.000-0.0018 cm), and wherein the inner diameter is approximately 1.043.+-.0.003 inches (2.6492.+-.0.0076 cm).