High-Pressure Pump Auxiliary Fuel Chamber Cooling
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Solution Overview
Problem
High-pressure pumps in direct-injection engines face issues with vapor lock and plunger seizure due to high-temperature fuel leaking from the pressurizing chamber, which existing cooling methods fail to adequately address, especially when the pressure increases.
Innovation Solution
A high-pressure pump design that includes a plunger, cylinder, pressurizing chamber, auxiliary fuel chamber, and return passage, where high-temperature fuel leaking through the clearance is collected and cooled externally, preventing vapor lock and seizure by efficiently cooling the fuel through an external cooling unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a large amount of low-temperature fuel is supplied to the cooling chamber to cool high-temperature fuel, then the temperature of high-temperature fuel is reduced, but the load of the low-pressure pump increases
Solution Approach 1:
The harmful high-temperature fuel is extracted from the pressurizing chamber through the clearance between cylinder and plunger and collected in a separate auxiliary fuel chamber. This isolation allows the high-temperature fuel to be cooled separately without requiring large amounts of low-temperature fuel from the main fuel supply, thereby reducing the load on the low-pressure pump while still achieving effective cooling.
Solution Approach 2:
The fuel system is segmented into main fuel chamber and auxiliary fuel chamber. The auxiliary fuel chamber specifically receives and cools the high-temperature leaked fuel separately from the main fuel supply system. This segmentation enables targeted cooling of only the problematic high-temperature fuel portion rather than cooling the entire fuel supply, reducing the cooling demand on the low-pressure pump.
2Stress or pressure
If the pressure applied by the high-pressure pump is increased beyond the pressure in the related art, then the pumping capability is improved, but the temperature of the fuel leaking out from the pressurizing chamber is more considerably increased
Solution Approach 1:
The high-temperature leaked fuel, which was previously a harmful byproduct causing vapor lock and seizure, is converted into a manageable stream by collecting it in the auxiliary fuel chamber. The return passage provides a dedicated cooling pathway that efficiently removes the excess heat generated by high-pressure operation, transforming the harmful thermal effect into a controlled cooling process that enables higher pumping pressures without the risk of vapor lock.
3Temperature
If existing cooling methods are used to cool high-temperature fuel, then some cooling effect is achieved, but sufficient and effective cooling cannot be achieved at high pressures
Solution Approach 1:
The auxiliary fuel chamber acts as an intermediary between the pressurizing chamber and the return passage. It collects the high-temperature leaked fuel and provides a dedicated cooling pathway through the return passage to an external cooling unit. This intermediary structure ensures that only the high-temperature leaked fuel is cooled through this efficient pathway, providing sufficient and effective cooling even at high pressures where conventional methods fail.
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 design effectively prevents vapor lock and plunger seizure by ensuring sufficient cooling of high-temperature fuel, even at increased pressures, and reduces component costs through simplified manufacturing processes.
Implementation Method 1
a plunger (41) which slides inside an inner wall surface of a cylinder (20) so as to suction fuel supplied from a low-pressure pump (92) to pressurize the fuel in a pressurizing chamber (22)
Implementation Method 2
the fuel leaking out from the pressurizing chamber to a non-pressurizing chamber side through a clearance between the cylinder and the plunger has a high temperature due to heat generation
Implementation Method 3
the collected fuel flows toward the external cooling unit through the return passage
Implementation Method 4
Fuel leaking out from the pressurizing chamber through a clearance between the cylinder and the plunger is collected inside the auxiliary fuel chamber, and the collected fuel flows toward the external cooling unit through the return passage
Data Source
AI summary
A high-pressure pump includes a plunger, a cylinder, a pressuring chamber, a pump body, a main fuel chamber, an auxiliary fuel chamber and a return passage. The cylinder slidably houses the plunger therein. The pump body houses the cylinder and has an end surface on an opposite side of the pump body relative to the pressurizing chamber in an axial direction. The main fuel chamber is in the pump body. The auxiliary fuel chamber has a side defined by one end of the cylinder on an opposite side of the cylinder relative to the pressurizing chamber. The return passage is inside the pump body and is in fluid communication with an external cooling unit. Fuel leaking out from the pressurizing chamber through a clearance between the cylinder and the plunger is collected inside the auxiliary fuel chamber, and the collected fuel flows toward the external cooling unit through the return passage.