Cam Ring Topology for Uniform Pressure Distribution
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Solution Overview
Problem
Existing hydrostatic positive displacement machines experience increased wear due to non-uniform surface pressure distribution between the cam ring and housing, particularly at higher pressures, leading to complex and costly solutions such as rolling or revolving contact support.
Innovation Solution
The implementation of a cam ring with a topology that deviates from a plane in the load-free mode, optimizing the outer circumferential surface segment to distribute surface pressure uniformly and reduce stress peaks, allowing for lower wear without the need for complex support mechanisms, achieved through methods like erosion or 3-D milling and finite element design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the cam ring is supported on inner surface segments of the housing by its outer circumferential surface segments, then the displacement volume can be adjusted, but non-uniform surface pressure distribution occurs leading to increased wear at higher pressures
Solution Approach 1:
The outer circumferential surface segment is given a specific non-planar topology with elevated edge regions and a depressed central region. This local geometric variation creates a non-uniform initial surface configuration that compensates for the non-uniform pressure distribution during operation, resulting in more uniform contact pressure and reduced wear at high pressures.
Solution Approach 2:
The cam ring's outer circumferential surface is designed with curved topographic features rather than flat surfaces. The elevated edge regions and depressed central region create a three-dimensional curved topology that optimizes contact pressure distribution with the housing surface, transforming the pressure distribution from non-uniform to more uniform under load.
2Reliability
If groove profiles are formed in the surface segments to create a hydrostatic relief field, then friction is reduced, but production cost increases
Solution Approach 1:
Instead of adding grooves to create hydrostatic relief, the invention changes the topographic parameters of the outer circumferential surface itself. By elevating the edges and depressing the center region, the surface topology is modified to inherently distribute pressure uniformly, eliminating the need for additional grooving operations and associated production costs.
3Reliability
If rolling or revolving contact support is used for the cam ring, then wear is reduced, but device complexity increases
Solution Approach 1:
The cam ring's outer circumferential surface is designed to self-optimize its contact characteristics with the housing through its inherent non-planar topology. The elevated edges and depressed center create automatic pressure distribution equalization during operation, eliminating the need for external rolling or revolving support mechanisms and keeping the device simple.
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
This approach reduces wear by ensuring force transmission occurs via the entire outer surface segment, minimizing surface pressure and stress peaks, thus extending the lifespan of the machine while maintaining a simplified and cost-effective design.
Implementation Method 1
optimizing the outer circumferential surface segment to distribute surface pressure uniformly and reduce stress peaks
Implementation Method 2
When some of the working spaces are in pressure medium connection with the high pressure, deformation of the cam ring results from the pressure force acting on the cam ring
Implementation Method 3
achieved through methods like erosion or 3-D milling and finite element design
Data Source
AI summary
A hydrostatic positive displacement machine has a cam ring for adjusting the displacement volume thereof. This cam ring is guided in translation by approximately diametrically arranged outer circumferential surface segments on associated inner surface segments of a housing of the positive displacement machine.