Cam Ring Bearing Flow Control for Vane Pump Efficiency
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Solution Overview
Problem
Current rotating ring vane pumps experience reduced mechanical and volumetric efficiency at low speeds due to insufficient friction between the cam ring and vanes, leading to increased parasitic leakage and larger pump sizes, which are undesirable for fuel systems.
Innovation Solution
A variable displacement pump with a fluid bearing supports the cam ring, and a valve system regulates fluid flow to the bearing, allowing selective reduction or termination of cam ring bearing flow at low speeds to enhance efficiency and reduce pump size and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If cam ring bearing flow is curtailed to increase volumetric efficiency, then pump flow capacity increases, but mechanical efficiency is significantly reduced
Solution Approach 1:
The patent applies dynamics by making the bearing flow supply conditional rather than static. The cam ring bearing flow is dynamically controlled based on operating conditions - supplied when pump speed is below a threshold to maintain mechanical efficiency, and curtailed when pump speed exceeds the threshold to maximize volumetric efficiency and flow capacity. This dynamic adaptation resolves the contradiction between mechanical efficiency and pump flow capacity.
Solution Approach 2:
The patent changes the parameter of bearing flow supply from constant to variable based on pump speed. By monitoring pump speed and adjusting the bearing flow parameter accordingly (supplied below threshold speed, curtailed above threshold speed), the system optimizes the balance between mechanical efficiency and volumetric efficiency, resolving the contradiction between these two performance metrics.
2Weight of moving object
If pump flow capacity is minimized to reduce physical size and weight, then pump size and weight decrease, but parasitic internal leakage increases
Solution Approach 1:
The patent applies local quality by providing bearing flow selectively to specific operating conditions rather than uniformly across all conditions. The flow control mechanism ensures that bearing flow is supplied locally (at low speeds) where it is needed to prevent leakage, while being curtailed at high speeds where full flow capacity is required. This localized quality control reduces overall parasitic leakage without requiring increased pump size.
3Loss of energy
If cam ring bearing flow is supplied continuously to maintain mechanical efficiency, then mechanical efficiency is maintained, but pump sizing is forced to accommodate engine start conditions
Solution Approach 1:
The patent applies periodic action by supplying bearing flow only during specific periods or conditions (low pump speeds below the threshold) rather than continuously. The flow control mechanism periodically activates bearing flow supply based on speed conditions, maintaining mechanical efficiency when needed while allowing full flow capacity during high-speed operation, thus avoiding the constraint of sizing for engine start conditions only.
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 solution improves mechanical and volumetric efficiency by reducing parasitic leakage, allowing the pump to be sized for more desirable take-off conditions, resulting in a smaller, lighter package with optimized performance across a range of operating conditions.
Implementation Method 1
This journal bearing acts as a combination hydrostatic and hydrodynamic bearing
Implementation Method 2
This journal bearing acts as a combination hydrostatic and hydrodynamic bearing
Implementation Method 3
The cam ring that is supported by the bearing is driven by friction between the cam ring at the interface with the vanes
Data Source
Figure 1~2
Figure 3~4
AI summary
A pump assembly includes a housing having a chamber in communication with an inlet and an outlet. A rotating ring, variable displacement vane pump is received in the chamber. The pump, and particularly the rotating ring, is supported by a fluid bearing in the chamber. A control is provided for selectively altering fluid flow to the bearing in response to one of hydrodynamic bearing pressure, boost flow pressure, and the pump stroke.