Scroll Compressor Sliding Bearing With Spherical Graphite
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Solution Overview
Problem
Bearing used in scroll compressors face issues with poor lubrication in mixed refrigerant atmospheres and high-speed high-load conditions, leading to durability and noise problems, and existing sliding bearings lack seizure and abrasion resistance, while roll bearings require high accuracy and are costly, and flake-shaped graphite orientations cause wear.
Innovation Solution
A scroll compressor with sliding bearings featuring a graphite-based resin layer on a back metal, where graphite particles have a high degree of graphitization, spherical shape, and specific shape factors, providing improved seizure and wear resistance, and reducing friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If flake-shaped graphite is used in sliding bearings, then lubrication is provided, but graphite orientation causes wear and reduces durability
Solution Approach 1:
The patent replaces flake-shaped graphite with spherical graphite particles having a shape factor of 0.8 or more. This spheroidality prevents orientation during operation, eliminating the wear problem caused by aligned flake graphite while maintaining effective lubrication through the spherical particles rolling and distributing evenly in the resin matrix.
Solution Approach 2:
The patent changes the shape parameter of graphite from flake-shaped to spherical by specifying a shape factor of 0.8 or more. It also controls the graphitization degree parameter at 0.6 or more to ensure proper lubrication properties. These parameter changes transform the graphite behavior from orientation-prone to orientation-resistant while maintaining lubrication effectiveness.
2Reliability
If roll bearings are used to ensure durability, then reliability improves, but manufacturing cost and complexity increase
Solution Approach 1:
The patent employs a sliding bearing with a relatively simple structure that can be manufactured more economically than roll bearings. By using spherical graphite particles in a resin matrix, the bearing achieves adequate durability without requiring the complex precision manufacturing of roll bearings, effectively replacing an expensive component with a more affordable alternative that meets performance requirements.
Solution Approach 2:
The patent creates a composite sliding bearing material combining resin matrix with spherical graphite particles (5-60 wt%). This composite provides the necessary durability and lubrication properties, replacing the need for expensive roll bearings while achieving comparable or sufficient performance at lower manufacturing cost and complexity.
3Reliability
If graphite content is increased to improve lubrication, then seizure resistance improves, but material strength decreases
Solution Approach 1:
The patent optimizes the graphite content parameter to a specific range of 5-60 wt% and controls the shape factor at 0.8 or more. This parameter combination ensures sufficient lubrication and seizure resistance while maintaining adequate material strength. The spherical shape and controlled content prevent both insufficient lubrication and excessive softening.
Solution Approach 2:
The patent creates local quality differentiation by using spherical graphite particles that distribute uniformly throughout the resin matrix. This uniform distribution ensures consistent lubrication properties and maintains structural integrity, achieving both seizure resistance and strength through optimized local material composition rather than uniform high graphite content.
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 enhances wear resistance, seizure resistance, and quietness, while reducing the size and weight of the compressor, and is cost-effective by using uniformly dispersed graphite, maintaining consistent wear conditions and improving durability.
Implementation Method 1
a sliding layer which graphite having a high degree of graphitization and a unique shape is dispersed in a resin
Data Source
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AI summary
[Problem] To exchange the roller bearing that has been used in a scroll compressor mounted in an automobile with a m slide bearing. To provide a slide bearing having a performance that is at least equivalent to that of a roller bearing. [Solution] The slide bearing results from baking onto a back metal a sliding layer of 5-60 wt% graphite having an average diameter of 5-50 µm and a graphitization degree of at least 0.6, the remainder comprising a polyimide resin and/or a polyamide-imide resin. The form of the graphite has: (a) an average shape factor (YAVE) as defined of 1-4 for the particles excluding the minute particles that are no greater than 0.5 times the average diameter, and there being at least 70% by number of particles having a shape factor (Y) in the range of 1-1.5; or (b) graphite particles having a particle ratio of at least 0.5 being at least 50% of the total by number.