Dual-Material Bushing Piston for Compressor Wear Reduction

Solution Overview

Problem

Compressor unloader piston assemblies experience excessive wear on sealing members and piston bore damage due to side forces, requiring premature replacement of sealing members and accelerating wear, while separate guide features increase manufacturing costs and complexity.

Innovation Solution

A piston and cylinder assembly with a housing and piston that uses two bushings of different materials around different portions of the piston to guide it within the bore, reducing side loads on sealing members and preventing damage, eliminating the need for separate guide features.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If separate guide features are used to shield the unloader piston o-rings from side forces, then the sealing members are protected from excessive wear, but manufacturing costs and complexity increase

Engineering Contradiction:

Improvesealing member durabilityVSAvoidmanufacturing complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The guide features are merged with the piston body itself, integrating the guiding function into the piston structure rather than using separate guide components. This eliminates the need for additional separate guide features while still protecting the sealing members from side forces, thereby reducing manufacturing complexity and costs while maintaining reliability

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The piston body is designed to serve multiple functions: it provides the sealing surface for the o-rings, guides the piston movement within the bore, and shields the sealing members from side forces through integrated guide features. This multi-functionality eliminates the need for separate dedicated guide components, reducing overall device complexity while maintaining protective function

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If separate guide features are used to shield the unloader piston o-rings from side forces, then the sealing members are protected from excessive wear, but manufacturing costs increase

Engineering Contradiction:

Improvesealing member durabilityVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The guide features are merged with the piston body itself, integrating the guiding function into the piston structure rather than using separate guide components. This eliminates the need for additional separate guide features while still protecting the sealing members from side forces, thereby reducing manufacturing complexity and costs while maintaining reliability

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The piston body is designed to serve multiple functions: it provides the sealing surface for the o-rings, guides the piston movement within the bore, and shields the sealing members from side forces through integrated guide features. This multi-functionality eliminates the need for separate dedicated guide components, reducing overall device complexity while maintaining protective function

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Ease of manufacture

If traditional single-material bushings are used, then manufacturing is simpler, but the piston cannot effectively handle varying side forces at different portions

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidpiston guidance effectiveness

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

Different portions of the piston are equipped with bushings made of different materials optimized for their specific functional requirements. The first bushing material is selected for its properties suitable for the first portion's operating conditions, while the second bushing material is selected for the second portion's conditions. This local differentiation improves the effectiveness of side force management and piston guidance while maintaining reasonable manufacturing simplicity

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The piston assembly uses composite construction with multiple materials - specifically, different bushing materials applied to different portions of the piston. This composite approach allows each bushing to be optimized for its specific location and loading conditions, improving overall reliability and guidance effectiveness while remaining manufacturable through established composite manufacturing techniques

Inventive Principle:

Principle #40Composite materials

Data Source

PatentUS8573113B2Piston and cylinder assembly

Publication Date: 2013.11.05 BENDIX COMMERCIAL VEHICLE SYSTEMS LLC

AI summary

A piston and cylinder assembly includes a housing defining a bore. A piston is sized to reciprocate in the bore. A first sealing member provides a sealing engagement between the piston and a wall of the bore. A first bushing, of a first material, is around a first portion of the piston toward a first end of the piston. A second bushing, of a second material, is around a second portion of the piston toward a second end of the piston. The first and second bushings guide the piston within the bore. The first material is different than the second material.