High Pressure Fuel Pump Zero Flow Lubrication Control
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Solution Overview
Problem
Existing zero flow lubrication strategies for high pressure fuel pumps in internal combustion engines face errors due to changes in fuel system bulk modulus, leading to inadequate lubrication and increased fuel pressure when conditions differ from nominal conditions.
Innovation Solution
A method that learns a transfer function between duty cycle and fuel rail pressure for nominal bulk modulus conditions and applies it at non-nominal conditions with a correction factor based on instantaneous bulk modulus estimates, ensuring proper lubrication without raising fuel rail pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a transfer function learned at nominal bulk modulus conditions is applied at non-nominal conditions, then the zero flow lubrication control is simpler, but errors occur leading to inadequate lubrication and increased fuel pressure
Solution Approach 1:
The patent implements dynamic adaptation of the transfer function by introducing a bulk modulus correction factor that adjusts the duty cycle based on real-time fuel bulk modulus estimates. This transforms the static transfer function into a dynamic one that adapts to changing fuel conditions, resolving the contradiction between control simplicity and lubrication accuracy.
Solution Approach 2:
The patent changes the parameter of the transfer function by applying a correction factor based on bulk modulus variations. Instead of using a fixed transfer function, the system modifies the duty cycle parameter dynamically according to the estimated bulk modulus, allowing the same transfer function structure to work across different fuel conditions while maintaining accuracy.
2Ease of manufacture
If the transfer function is learned at nominal conditions only, then the learning process is simpler, but it cannot adapt to various fuel types and temperature conditions
Solution Approach 1:
The patent makes the transfer function universal by adding a bulk modulus correction mechanism that allows a single learned transfer function to work across multiple fuel types and temperature conditions. The correction factor acts as an adapter that enables the nominal-condition transfer function to function correctly under diverse conditions without requiring separate transfer functions for each scenario.
Solution Approach 2:
The bulk modulus correction factor serves as an intermediary between the nominal-condition transfer function and the actual operating conditions. This intermediary component translates the effects of varying fuel properties into appropriate duty cycle adjustments, allowing the transfer function to adapt to different fuel types and temperatures without relearning.
3Duration of action of stationary object
If the duty cycle is adjusted to provide desired lubrication without raising rail pressure, then pump durability is improved, but errors in transfer function application may cause pressure increases
Solution Approach 1:
The patent implements feedback by continuously monitoring fuel rail pressure and using bulk modulus estimates to adjust the duty cycle. The system compares the actual pressure with the desired pressure and modifies the pump operation accordingly, ensuring that lubrication is maintained while preventing pressure excursions that could compromise control accuracy or pump durability.
Data Source
AI summary
Methods and systems are providing for improving zero flow lubrication (ZFL) of a high pressure fuel pump coupled to direct fuel injectors via a direct injection fuel rail. A ZFL transfer function for the fuel pump is learned while fuel is at non-nominal fuel bulk modulus conditions and corrected for variations from a nominal fuel bulk modulus estimate. When zero flow lubrication of the pump is requested, the pump is operated with a duty cycle based on the learned transfer function and an instantaneous estimate of the fuel bulk modulus to compensate for differences in fuel condition from the nominal fuel bulk modulus estimate.