High-Pressure Fuel Pump Plunger Sealing for Leakage and Seizure
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Solution Overview
Problem
Existing high-pressure fuel pumps face challenges in minimizing leakage between the pumping plunger and the plunger bore, while avoiding the risks of plunger seizure due to heat expansion and poor lubrication, which requires tight manufacturing tolerances and complex match honing processes.
Innovation Solution
The high-pressure fuel pump incorporates a pumping plunger with an annular sealing ring groove and a sealing ring that engages the plunger bore in an interference fit, providing radial and axial compression to minimize fuel leakage and accommodate a wider diametric clearance of 13 to 30 microns between the plunger and the bore.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If a plunger pump is used to supply high-pressure fuel, then the fuel can be supplied at high pressure, but the pump becomes large in size and complex in structure
Solution Approach 1:
The pump body is divided into a common rail and multiple separate injection nozzles. The common rail serves as a pressure accumulation chamber that receives fuel from the fuel pump, while each injection nozzle independently receives fuel from the common rail. This segmentation allows the system to achieve high pressure without requiring each individual injection point to be directly connected to a complex high-pressure pump mechanism.
Solution Approach 2:
The common rail serves multiple functions: it acts as a pressure accumulation chamber, a distribution manifold, and a pressure regulation system. By using a single common rail structure to serve multiple injection nozzles, the system reduces overall complexity while maintaining high-pressure fuel delivery capability across all cylinders.
2Stress or pressure
If a plunger pump is used to supply high-pressure fuel, then the fuel can be supplied at high pressure, but the pump becomes large in size
Solution Approach 1:
The pump body is divided into a common rail and multiple separate injection nozzles. The common rail serves as a pressure accumulation chamber that receives fuel from the fuel pump, while each injection nozzle independently receives fuel from the common rail. This segmentation allows the system to achieve high pressure without requiring each individual injection point to be directly connected to a complex high-pressure pump mechanism.
Solution Approach 2:
The common rail serves multiple functions: it acts as a pressure accumulation chamber, a distribution manifold, and a pressure regulation system. By using a single common rail structure to serve multiple injection nozzles, the system reduces overall complexity while maintaining high-pressure fuel delivery capability across all cylinders.
3Productivity
If a in-cylinder injection system is used, then fuel can be injected directly into the combustion chamber, but the injection system becomes complex and expensive
Solution Approach 1:
The pump body is divided into a common rail and multiple separate injection nozzles. The common rail serves as a pressure accumulation chamber that receives fuel from the fuel pump, while each injection nozzle independently receives fuel from the common rail. This segmentation allows the system to achieve high pressure without requiring each individual injection point to be directly connected to a complex high-pressure pump mechanism.
Solution Approach 2:
The common rail acts as an intermediary between the fuel pump and the injection nozzles. It receives high-pressure fuel from the pump, maintains pressure, and distributes fuel to multiple nozzles. This intermediary structure simplifies the overall system by decoupling the high-pressure generation function from the injection function, allowing each component to be optimized independently.
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 design enhances the efficiency of the high-pressure fuel pump, particularly at low rotational speeds, by reducing fuel leakage and minimizing the risk of plunger seizure, thereby allowing for a downsized fuel pumping capacity and eliminating the need for costly match honing processes.
Implementation Method 1
a sealing ring which engages the plunger bore in an interference fit to prevent fuel from escaping the pumping chamber between the interface of the pumping plunger and the plunger bore
Implementation Method 2
A pumping plunger is reciprocated within the plunger bore by a camshaft of the internal combustion engine such that each cycle of the pumping plunger increases and decreases the volume of the pumping chamber
Implementation Method 3
The pumping plunger is attached to a cam follower which contacts a cam shaft, in use, to drive reciprocating movement of the pumping plunger
Implementation Method 4
a return spring is compressed axially between the pump housing and the cam follower to maintain the cam follower in contact with the camshaft, in use
Data Source
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AI summary
A high-pressure fuel pump (22) includes a pump housing (30) which defines a pumping chamber (32), a fuel inlet (38) which allows low-pressure fuel into the pumping chamber (32), a fuel outlet (40) which allows high-pressure fuel out of the pumping chamber (32), and a plunger bore (34) which extends along an axis (36) and opens into the pumping chamber (32). The high-pressure fuel pump (22) also includes a pumping plunger (42) which reciprocates within the plunger bore (34) along the axis (36) such that reciprocation of the pumping plunger (42) within the plunger bore (34) increase and decreases a volume of the pumping chamber (32). The pumping plunger (42) includes a sealing ring groove (64) which is concentric with the plunger bore (34), the sealing ring groove (64) including a sealing ring (66) therein which engages the plunger bore (34) in an interference fit. A diametric clearance greater than 12 microns is provided between the pumping plunger (42) and the plunger bore (34).