High-Pressure Fuel Pump Bearing Cooling via Return Line Valve Inversion
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Solution Overview
Problem
Conventional high-pressure fuel pumps for internal combustion engines face increasing mechanical and thermal loads due to rising injection pressures, leading to inadequate bearing capacity and potential cavitation issues.
Innovation Solution
The pressure regulating valve is positioned in the fuel return line, allowing the majority of the prefeed pump's fuel to flow through the pump housing for enhanced cooling and lubrication, and a flow limiting device is used to maintain consistent fuel flow through the bearings, ensuring adequate lubrication and cooling across all operating points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the pressure regulating valve is positioned in the low-pressure circuit as in conventional pumps, then the pump structure is simple, but the bearing capacity is insufficient under increasing injection pressures
Solution Approach 1:
The pressure regulating valve is inverted from its conventional position in the low-pressure circuit to the fuel return line. This inversion changes the pressure distribution in the pump housing, creating elevated pressure that improves bearing capacity and prevents cavitation, while the valve itself remains a standard component.
Solution Approach 2:
The patent changes the pressure parameter distribution within the pump housing by repositioning the pressure regulating valve. This creates a pressure gradient that elevates the pressure environment for the bearings, transforming the thermal and mechanical bearing capacity without changing the bearing components themselves.
2Productivity
If injection pressure is increased to improve fuel injection performance, then the fuel injection system becomes more efficient, but thermal and mechanical loads on the drive shaft and bearings increase
Solution Approach 1:
The patent changes the pressure parameter in the pump housing by repositioning the pressure regulating valve to the fuel return line. This creates an elevated pressure environment that counteracts the increased mechanical loads from higher injection pressures, maintaining bearing reliability while allowing high injection pressure operation.
Solution Approach 2:
The elevated pressure in the pump housing, created by the repositioned pressure regulating valve, acts as a preliminary countermeasure against the increased thermal and mechanical loads. This pre-established pressure environment prevents cavitation and reduces the net load on bearings before the high injection pressure cycles begin.
3Temperature
If fuel flow through the pump housing is increased to improve cooling, then thermal management improves, but the risk of cavitation increases
Solution Approach 1:
The patent changes the pressure parameter distribution by repositioning the pressure regulating valve, creating an elevated pressure environment in the pump housing. This pressure elevation allows increased fuel flow for cooling while preventing cavitation, as the higher ambient pressure raises the cavitation threshold.
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 configuration increases the thermal and mechanical bearing capacity, reduces cavitation, and prevents local overheating, while simplifying the pump construction and reducing production variations' impact on bearing performance.
Implementation Method 1
the first bearing is lubricated by fuel under pressure; and that the first bearing is in hydraulic communication with both the fuel feed line and the fuel return line
Implementation Method 2
the pressure regulating valve serves to regulate the pressure in the low-pressure circuit of the high-pressure fuel pump
Implementation Method 3
a prefeed pump that pumps fuel into the fuel feed line
Implementation Method 4
the majority of the fuel pumped by the prefeed pump flows through the pump housing and as a result contributes to improved cooling of the pump housing and of the drive shaft
Data Source
AI summary
The invention relates to a high-pressure fuel pump comprising a drive shaft supported by bearings, and fuel flows through the bearings in a forced manner in such a way that the mechanical and thermal load-carrying capacity of the bearings, and thus the entire high-pressure fuel pump, is significantly increased.