Gear Pump with Etched Surfaces for High-Pressure Lubrication
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Solution Overview
Problem
Fuel pumps with leaded bronze bearings face limitations in operational pressure, temperature, and speed due to reduced lubrication film thickness at high temperatures and increased wear from vapor-filled cavities, leading to galling and friction welding issues.
Innovation Solution
The introduction of chamfered portions on the radially outwardly facing surfaces of gear teeth, which enhance lubricant retention and fluid film thickness, allowing for increased pressures and speeds while using non-traditional bearing and gear material couples, and improving heat transfer and load-carrying capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If leaded bronze bearings are used, then conformability and thermal conductivity are improved, but operational pressure and temperature limits are reduced due to galling and friction welding
Solution Approach 1:
The patent applies different surface properties to different regions of the bearing. The bearing surface is selectively coated or treated to create zones with varying friction and wear characteristics. This allows the bearing to maintain conformability and thermal conductivity of leaded bronze while introducing local regions that resist galling and friction welding at critical contact points.
Solution Approach 2:
The patent combines leaded bronze bearing material with additional surface layers or coatings that provide enhanced resistance to galling and friction welding. This composite approach maintains the base material's conformability and thermal conductivity while adding protective surface properties that enable operation at higher pressures and temperatures.
2Temperature
If fuel temperature increases, then cooling capability is improved, but lubricating film thickness is reduced leading to increased wear
Solution Approach 1:
The patent modifies surface parameters of the bearing or gear surfaces to maintain adequate lubricating film thickness at elevated temperatures. This may include changing surface roughness, introducing micro-dimples or reservoirs for lubricant retention, or applying coatings that maintain lubrication properties at high temperatures despite reduced fuel viscosity.
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 chamfered portions increase the fluid film thickness to full hydrodynamic lubrication, enhancing the service life of the pump, supporting higher operational ranges without loss of lubrication and reducing friction and heat generation.
Implementation Method 1
The chamfered portions increase the fluid film thickness to full hydrodynamic lubrication
Implementation Method 2
The fuel, in addition to being passed through the pump, acts primarily as a coolant and a lubricant for pump components
Implementation Method 3
The fuel, in addition to being passed through the pump, acts primarily as a coolant and a lubricant for pump components
Data Source
AI summary
A gear for a pump includes a gear body defining a root circle, and a plurality of gear teeth extending from the gear body radially outwardly of the root circle. Each of the plurality of gear teeth have a tip portion, a leading edge, a trailing edge, a circular thickness defined between the leading edge and the trailing edge, a first radially outwardly facing surface and a second radially outwardly facing surface. At least one of the first radially outwardly facing surface and the second radially outwardly facing surface includes a chamfered portion that extends from the leading edge toward the trailing edge across a portion of the circular thickness.