High-Pressure Pump Leakage Line Routing for Thermal Management
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Solution Overview
Problem
Conventional high-pressure pump arrangements experience overheating and reduced service life due to leakage fuel recirculation, especially during part-load operation, leading to uneven heating and decreased conveying capacity.
Innovation Solution
The scavenging line is connected to the pump suction chamber, allowing leakage fuel to be flushed into a low-pressure area, and a separate flushing line with a throttle is used to manage fuel flow, preventing excessive heating by ensuring continuous scavenging even during zero delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional leakage line returns leaked fuel to the pump suction chamber, then the fuel is recirculated, but this causes significant heating of the pump elements and reduces service life
Solution Approach 1:
The harmful recirculation path is extracted and removed from the system. The leakage line is disconnected from the pump suction chamber and instead leads directly to the tank, eliminating the heating circuit that caused excessive temperature rise in pump elements during part-load operation.
Solution Approach 2:
The leaked fuel, which previously caused harmful heating when recirculated, is now redirected to serve a beneficial cooling function. By leading the leakage fuel directly to the tank, it removes heat from the system rather than adding it, converting a harmful thermal effect into a beneficial cooling effect.
2Loss of substance
If the metering unit is closed during zero delivery, then fuel loss is reduced, but fuel still escapes from the metering unit outlet and can enter the pump working chamber
Solution Approach 1:
A flushing line acts as an intermediary path between the metering unit outlet and the pump suction chamber. This flushing line with its throttle allows controlled passage of fuel to prevent pressure buildup that would force fuel into the pump working chamber, while the separate leakage line provides an additional safety path directly to the tank.
Solution Approach 2:
The fuel control system is segmented into separate functional paths: a flushing line with throttle for pressure control, a leakage line with valve for direct tank return, and the main metering path. This segmentation allows independent control of each function to simultaneously achieve fuel loss reduction and pump protection.
3Ease of operation
If the flushing line with throttle is used to discharge leakage fuel, then fuel flow is controlled, but the throttle can become clogged with abrasive solids in heavy oil
Solution Approach 1:
Different parts of the system have different quality requirements: the flushing line throttle handles clean fuel from the tank, while the leakage line valve handles fuel that has already been through the pump and contains abrasive solids. This local differentiation of quality requirements prevents clogging by directing contaminated fuel away from the sensitive throttle.
Solution Approach 2:
Instead of having the flushing line handle all leakage fuel control, the system inverts the approach by having the leakage line with its more robust valve handle the contaminated fuel from the pump, while the flushing line with the sensitive throttle handles only clean fuel from the tank.
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 effectively prevents the formation of heating circuits and reduces overheating, thereby extending the service life and maintaining efficient operation of high-pressure pump elements.
Implementation Method 1
the leakage flows occurring at pressures of around 2000 bar during the pumping process cause significant heating
Implementation Method 2
at least one flushing line having a throttle for discharging a flushing quantity coming from the metering unit from the fuel supply downstream of the metering unit leading away a low pressure area
Implementation Method 3
the high-pressure pump serves to pump fuel from a fuel tank into a high-pressure container, the so-called rail, with the fuel in the high-pressure container being kept under sufficient pressure to allow the fuel to be injected into the combustion chamber
Implementation Method 4
the pump chamber of which can be connected via a suction valve to a pump suction chamber fed by a fuel supply
Data Source
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AI summary
In a high-pressure pump arrangement for pumping combustible fuel from a tank into a high-pressure container, wherein at least one pump element consisting of pump cylinder and pump piston is provided whose pump chamber can be connected via a suction valve to a pump suction chamber supplied by a fuel supply and via a pressure valve to the high-pressure container, wherein the pump element comprises a leakage line for returning into the pump suction chamber leakage fuel which flows off between pump piston and pump cylinder, and wherein the fuel supply has a metering unit, and at least one purging line, having a throttle, for evacuating a purging quantity coming from the metering unit into a low-pressure region leads off from the fuel supply downstream of the metering unit, the at least one purging line (24, 24') is connected to the pump suction chamber (12) such that the purging quantity flows through the pump suction chamber (12).