Cabin Air Compressor Cover Plate Thermal Expansion
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Solution Overview
Problem
In cabin air compressors, the cover plate often binds during movement due to radial expansion of the diffuser housing and cover plate, leading to performance issues.
Innovation Solution
A cylindrical cover plate with a specific inner diameter and thickness is designed to reduce binding, featuring 19 holes for pin engagement, made from 300 series corrosion-resistant steel, allowing for optimized rotation and reduced leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cover plate and diffuser housing are made from corrosion-resistant materials and operate under high temperature conditions, then reliability and durability are improved, but thermal expansion causes radial growth leading to binding between the cover plate
Solution Approach 1:
The patent applies parameter changes by modifying the inner diameter of the cover plate from 14.825 inches to 14.840 inches, creating a 0.015-inch clearance gap. This dimensional parameter change compensates for thermal expansion of both the cover plate and diffuser housing, preventing binding while maintaining reliability under high-temperature operating conditions.
Solution Approach 2:
The patent implements beforehand cushioning by pre-establishing a clearance gap through the enlarged inner diameter. This gap acts as a buffer that absorbs the radial expansion that occurs during operation, preventing direct contact and binding between the cover plate and diffuser housing before the expansion problem can manifest.
2Ease of operation
If the cover plate inner diameter is increased to prevent binding, then ease of operation is improved, but leakage between the cover plate and diffuser housing increases
Solution Approach 1:
The patent optimizes the inner diameter parameter to 14.840 inches, which is sufficiently enlarged to prevent binding during operation but controlled to minimize leakage. This precise parameter adjustment balances the conflicting requirements of smooth rotation and leakage prevention.
Solution Approach 2:
The patent applies local quality by providing 19 holes through the cover plate body. These localized features allow pins to engage with the drive ring, creating discrete contact points that maintain proper positioning and sealing at critical locations while the overall enlarged diameter prevents binding.
3Temperature
If the cover plate thickness is reduced to minimize thermal mass and expansion, then thermal expansion effects are reduced, but structural strength and durability decrease
Solution Approach 1:
The patent specifies that the cover plate be made from 300 series corrosion-resistant steel, a composite material formulation that provides optimal balance between thermal expansion properties and structural strength. This material selection allows the plate to maintain adequate thickness for strength while having controlled thermal expansion characteristics.
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 effectively minimizes binding and ensures smooth operation by maintaining optimal clearance between the cover plate and diffuser housing, enhancing airflow control and compressor performance.
Implementation Method 1
The cover plate may be associated with the drive ring and rotating within a channel in the diffuser housing. In the past, this cover plate has sometimes binded during movement.
Implementation Method 2
the cover plate often binds during movement due to radial expansion of the diffuser housing and cover plate
Data Source
AI summary
A cover plate for use in a cabin air compressor is a generally cylindrical body with 19 holes extending through the body and an inner bore defining an inner diameter centered on a center axis. The body has a thickness in a dimension measured perpendicular to the central axis. The inner diameter is 14.840 inches (37.693 centimeters) plus/minus .005 inch (0.013 centimeter). A diffusor housing, a cabin air compressor and a method of replacing a cover plate are also disclosed.