Overflow Valve Spring Chamber Pulsation Control
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Solution Overview
Problem
New high-pressure pump concepts in fuel injection systems cause disruptive pressure pulsations in the line system of fuel supply devices, leading to inefficiencies and strong pulsations in the low-pressure circuit.
Innovation Solution
The overflow valve is designed to move synchronously with the stroke frequency of the high-pressure pump, using a Venturi nozzle to connect the spring chamber to the suction side, creating a medium negative pressure and reducing fuel leakage, thereby minimizing pulsations by diverting fuel leakage from the spring chamber and reducing the fuel cushion in the spill line.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional overflow valve is used with a spring chamber connected to the spill line via hydraulic connecting lines with throttles, then the valve can divert excess fuel, but disruptive pressure pulsations occur in the line system due to strong displacement effects in the low-pressure circuit
Solution Approach 1:
The patent extracts the harmful pressure pulsations from the spring chamber by connecting it to the suction side of the high-pressure pump instead of the spill line. This removes the source of pulsations (fuel leakage in the spring chamber) from the return circuit, preventing them from propagating through the system.
Solution Approach 2:
The suction side of the high-pressure pump acts as an intermediary that absorbs pressure pulsations. By connecting the spring chamber to this intermediary, the system converts harmful pulsations into useful fuel delivery that can be regulated by the pump's suction mechanism, rather than transmitting them directly to the return line.
2Reliability
If the spring chamber is connected to the spill line with throttles, then fuel leakage can be diverted, but the valve piston's ability to oscillate is impaired due to hydraulic damping
Solution Approach 1:
The patent removes the hydraulic damping effect by extracting the spring chamber connection from the spill line circuit. Without the throttles in the spill line, the valve piston can oscillate freely in response to pressure changes, maintaining its ability to track pressure variations without being dampened by restricted flow paths.
3Stress or pressure
If fuel leakage accumulates in the spring chamber, then the valve can maintain pressure, but the play between the valve piston and cylinder guide caused by manufacturing losses is amplified
Solution Approach 1:
The patent extracts fuel leakage from the spring chamber by providing a dedicated suction connection to the high-pressure pump. This prevents fuel accumulation that would otherwise amplify the effects of manufacturing play between the valve piston and cylinder guide, allowing the valve to maintain pressure control without being sensitive to dimensional tolerances.
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 solution effectively absorbs and releases volume on the inlet side, reducing pressure pulsations in the fuel supply device, particularly in one- or two-piston high-pressure pumps, and decreases the influence of manufacturing play on valve piston movement, leading to a more stable operation.
Implementation Method 1
By connecting the spring chamber to the suction side of the Venturi nozzle, a medium negative pressure is specifically generated within the spring chamber
Data Source
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AI summary
The invention proposes a fuel supply device of a fuel injection system of an internal combustion engine, and an embodiment of the overflow valve (30) for the same. The fuel supply device has a high-pressure pump (18) in addition to the overflow valve (30). The overflow valve (30) conducts a nonrequired fuel quantity from the high-pressure pump (18) into a spill line (28). The overflow valve (30) has a spring chamber (32) which is hydraulically connected to the spill line (28). For the hydraulic connection of the spring chamber (32) to the spill line (28), a discharge line (29) is provided which is hydraulically connected to a suction side (41) of a Venturi nozzle (40).