Single-Sided Impeller Fuel Pump Axial Force Balancing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Regenerative fuel pumps have a high wet circle index, leading to significant friction losses and reduced efficiency when handling high-pressure fuel, necessitating a solution that maintains robust axial clearances while lowering the wet circle index.
Innovation Solution
A fuel pump design featuring a single-sided impeller that is free floating on a shaft, with a cover and body configuration that balances axial forces to maintain minimal clearance and reduce friction losses, allowing for efficient pressurization of fuel to at least 2 bar without the need for additional structural components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a double sided impeller is used to maintain robust axial clearances for high pressure fuel pumping, then the pump can handle high pressure fuel reliably, but the wet circle index becomes high leading to increased friction losses
Solution Approach 1:
The invention extracts one side of the impeller (removing vanes and flow channels from one axial side) to eliminate the corresponding friction losses and reduce the wet circle index, while maintaining the necessary axial clearance through the single-sided design and force balancing mechanism
Solution Approach 2:
The impeller is designed with asymmetric configuration where only one side has vanes and flow channels, creating an asymmetric structure that reduces the wet circle index while the force balancing mechanism ensures reliable operation at high pressures
2Loss of energy
If a single sided impeller is used to reduce the wet circle index and improve efficiency, then friction losses are reduced, but maintaining robust axial clearances becomes more difficult
Solution Approach 1:
The invention applies force balancing mechanism that creates counteracting forces on the impeller to maintain robust axial clearances. The cover-side force from fuel in the cover flow channel and the body-side force from fuel in the outlet passageway are sized to be approximately equal, providing axial balance without requiring bearings or additional structural components
Solution Approach 2:
The invention changes the geometric parameters of the impeller exposure areas - the exposed area on the body-side is sized to provide a body side axial force approximately equal to the cover-side axial force, and the pressure balance channels are positioned and sized to achieve force balance, thereby maintaining reliable axial clearances with a single-sided design
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 design effectively reduces the wet circle index by 20-35%, enhancing hydraulic efficiency and enabling the pump to handle high-pressure fuel efficiently, while maintaining the necessary axial clearance and balancing forces to prevent wear and ensure reliable operation.
Implementation Method 1
The impeller is connected to the shaft for rotation as well as for axial translation relative to the shaft. That is, the impeller is free floating on the shaft.
Implementation Method 2
rotation of the impeller and its vanes pressurizing the lower pressure fuel provided at an inlet end of the cover flow channel, which is forced to an outlet end of the cover flow channel
Implementation Method 3
one or both of the body and the cover may define pressure balance channels in fluidic communication with either high or low pressure fuel, which can be adjusted to provide a balanced impeller
Data Source
AI summary
A fuel pump is provided having improved efficiency by lowering the wet circle index of the pump while maintaining robust axial clearances to meet the demands of an automotive application. One embodiment includes a fuel pump for pressurizing fuel for delivery to an engine of a motor vehicle. The fuel pump generally comprises a housing, a motor, a single sided impeller, a cover and a body. The provision of a single sided impeller greatly reduces the wet circle index and improves the pump efficiency. The cover, impeller, and body are structured to axially balance the impeller which is free floating on the shaft of the motor.