Fuel Injection Pump Valve Timing to Suppress Cavitation Erosion
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Solution Overview
Problem
Conventional accumulator fuel injection apparatuses experience cavitation erosion and high-pressure fuel spilling due to rapid backflow, leading to reduced durability and increased energy consumption, especially in high-capacity pumps.
Innovation Solution
The apparatus controls the electromagnetic valve to close during the upstroke of the plunger and keep closed for a period during the downstroke, then opens to communicate the plunger room with the fuel feed/spill passage only when the pressure equals or decreases to the fuel feed/spill passage level, preventing rapid high-pressure fuel backflow and spilling, and utilizing a plunger with a lead edge to manage the inlet/spill port timing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the electromagnetic valve is opened when the plunger room pressure is high to allow rapid fuel discharge, then fuel injection efficiency is improved, but cavitation erosion and durability are worsened
Solution Approach 1:
The electromagnetic valve is opened in advance during the upstroke of the plunger, before the high-pressure fuel discharge phase, to allow low-pressure fuel to enter the plunger room. This preliminary action ensures that when the valve closes and high-pressure discharge begins, the plunger room is already filled with fuel at appropriate pressure, preventing cavitation erosion while maintaining injection efficiency.
2Stability of the object's composition
If the electromagnetic valve is opened early to allow fuel spillout, then pressure pulsation is reduced, but fuel leakage and energy loss increase
Solution Approach 1:
The control system monitors the plunger room pressure and the timing of plunger movement, and uses this feedback information to determine the optimal moment to open the electromagnetic valve. By opening the valve at the precise moment during the upstroke when pressure conditions are appropriate, the system reduces pressure pulsation during discharge while preventing excessive fuel spillout and energy loss.
3Object-generated harmful factors
If the electromagnetic valve remains closed longer during downstroke, then fuel spilling is prevented, but pressure buildup and cavitation risk increase
Solution Approach 1:
The electromagnetic valve timing is dynamically adjusted based on the real-time position and movement of the plunger. The valve is opened at a specific point during the upstroke and closed at a specific point during the downstroke, creating a dynamic control strategy that prevents fuel spilling while managing pressure buildup to avoid cavitation risk.
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 approach prevents cavitation erosion, enhances durability, reduces energy consumption by minimizing pressure pulsation and fuel leakage, and allows for a smaller fuel feed pump, thereby increasing energy efficiency.
Implementation Method 1
controlling opening/closing of a low pressure side fuel feed passage by means of an electromagnetic valve provided to each pump
Implementation Method 2
high pressure fuel pumps each of which compresses fuel introduced into its plunger room to high pressure by its plunger fitted in its plunger barrel and reciprocated by means of a fuel cam
Implementation Method 3
high pressure fuel remaining in the plunger room spills out from the plunger room to the fuel feed/spill passage of low pressure at high speed
Data Source
AI summary
A fuel injection apparatus for engines is provided, with which occurrence of cavitation erosion on constituent parts of the high pressure fuel pump and fuel feed line to the pump in the apparatus is suppressed and high durability is attained even in the case of a high pressure fuel pump increased largely in capacity. Each of high pressure fuel pumps to supply high pressure fuel to a common rail comprises an electromagnetic valve which is controlled by a controller such that fuel is discharged from the plunger room by closing the electromagnetic valve in the up stroke of the plunger until the plunger reaches its top dead center, the electromagnetic valve is kept closed for some period in the down stroke of the plunger, then the electromagnetic valve is opened to allow the plunger room to be communicated with a fuel feed/spill passage.