Fuel Supply System Pressure Control via Limit Valve
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Solution Overview
Problem
Internal combustion engines face challenges in reducing pollutant emissions while maintaining high torque, as increased injection pressure requires robust high-pressure components, and existing solutions are costly and inefficient.
Innovation Solution
A fuel supply system incorporating a high-pressure pump, pressure-limiting valve, and high-pressure fluid accumulator, where the high-pressure pump increases pressure to open the pressure-limiting valve, reducing pressure and minimizing fuel leakage, thus reducing emissions and production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If injection pressure is increased to reduce pollutant emissions, then emission reduction is improved, but high-pressure component requirements and system cost worsen
Solution Approach 1:
The system pre-charges the high-pressure accumulator to the nominal pressure (200-350 bar) before engine start. This preliminary action ensures that when the engine starts, fuel is already available at the required high pressure immediately, eliminating the need for complex high-pressure pumps and pressure control systems during operation.
Solution Approach 2:
The system uses periodic low-pressure pump operation to recharge the high-pressure accumulator when pressure drops below the nominal value. This periodic recharging replaces continuous high-pressure pumping, simplifying the system architecture while maintaining the ability to deliver high injection pressure when needed.
2Reliability
If high-pressure pump is continuously actuated to maintain injection pressure, then fuel supply reliability is improved, but energy consumption and fuel leakage worsen
Solution Approach 1:
The high-pressure pump operates periodically rather than continuously. The control unit activates the pump only when the accumulator pressure falls below the nominal pressure range (200-350 bar), thereby maintaining fuel supply reliability while dramatically reducing energy consumption compared to continuous operation.
Solution Approach 2:
The system uses the engine's own operation to drive the high-pressure pump through the crankshaft connection. The pump self-activates during engine operation without requiring external power, automatically recharging the accumulator when pressure drops, thus maintaining reliability without additional energy input.
3Loss of substance
If pressure-limiting valve is set to open at low pressure threshold, then fuel leakage prevention is improved, but injection pressure stability worsens
Solution Approach 1:
The pressure-limiting valve is configured with an opening threshold that is specifically set 50-90 bar above the nominal pressure (200-350 bar), meaning it opens at 250-440 bar. This parameter setting allows the system to maintain stable nominal pressure during operation while preventing excessive pressure buildup that would cause fuel leakage, thus balancing both requirements.
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 system achieves low-emission operation and cost-effective production by controlling pressure to prevent fuel leakage and unnecessary pump actuation, ensuring efficient fuel supply and reduced component stress.
Implementation Method 1
the high-pressure pump (3) is actuated such that, at the outlet side of the high-pressure pump (3), a pressure is increased such that the pressure-limiting valve (5) is opened
Implementation Method 2
the pressure-limiting valve (5) is, at the outlet side, connected in terms of flow to a low-pressure region of the fuel supply system (1) at the inlet side of the high-pressure pump (3)
Implementation Method 3
a high-pressure fluid accumulator (7). The high-pressure pump (3) is, at the outlet side, coupled in terms of flow to the pressure-limiting valve (5) and to the high-pressure fluid accumulator (7)
Data Source
AI summary
The present invention relates to a method for operating a fuel supply system for an internal combustion engine, and to a corresponding device. The fuel supply system of an internal combustion engine may include: an outlet of a high-pressure pump coupled to a pressure-limiting valve and a high-pressure fluid accumulator. The method may include, when the internal combustion engine is set into a deactivated state, actuating the high-pressure pump such that, at the outlet side of the high-pressure pump, a pressure is increased such that the pressure-limiting valve is opened.