Hydraulic Intake Valve Actuation System Refill Mechanism
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Solution Overview
Problem
The existing internal-combustion engine systems with hydraulic actuation for variable intake valve control face issues with fluid leakage over prolonged inactivity, leading to potential engine starting failures due to empty pressure chambers.
Innovation Solution
An auxiliary fluid tank is connected to the pressure chamber via a non-return valve, and the electronic control system is programmed to refill the pressure chamber before engine ignition by using the electrical machine to rotate the camshaft and control valve, acting as a suction pump to draw fluid from the auxiliary tank.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the hydraulic system is connected directly to the exhaust volume, then the system can be refilled during normal operation, but fluid leaks continuously from the pressure chamber during inactivity
Solution Approach 1:
The hydraulic system is segmented into two separate tanks: the first tank (exhaust volume) connected to the pressure chamber during operation, and the second tank (auxiliary tank) isolated from the pressure chamber. This segmentation allows the first tank to handle operational fluid exchange while the second tank serves as a protected reserve that prevents fluid loss during inactivity.
Solution Approach 2:
A non-return valve is introduced as an intermediary component between the second tank and the pressure chamber. This valve acts as a one-way gate that allows fluid to flow from the second tank to the pressure chamber when needed, but prevents any backflow or leakage, thus protecting the hydraulic system during prolonged inactivity.
2Reliability
If the electrical machine rotates the camshaft during cranking, then the pumping plunger can refill the pressure chamber, but fuel injection cannot occur simultaneously
Solution Approach 1:
The system performs preliminary refilling of the pressure chamber from the auxiliary tank before engine ignition is attempted. The electronic control unit detects low fluid levels during cranking and activates the refilling operation in advance, ensuring the hydraulic system is ready for valve actuation before fuel injection begins.
Solution Approach 2:
The electronic control unit implements periodic monitoring of fluid levels in the pressure chamber during the cranking phase. When insufficient fluid is detected, the system periodically activates the refilling mechanism until adequate fluid levels are restored, then transitions to normal fuel injection operations.
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
Ensures the hydraulic system is refilled automatically, preventing engine starting failures due to fluid leakage and maintaining system functionality after prolonged inactivity.
Implementation Method 1
a non-return valve (700) that enables passage of fluid only in a direction from the tank (600) to the pressure chamber (C)
Implementation Method 2
the pumping plunger functions as suction pump for recalling fluid from said auxiliary tank to the pressure chamber
Implementation Method 3
respective return springs that push them towards a closed position
Data Source
AI summary
In an engine having an electronically controlled hydraulic system for variable actuation of intake valves, an operating step of refilling, prior to ignition of the engine, is activated to refill a pressure chamber of the system with fluid when, after prolonged engine inactivity, the chamber has been emptied. In this refilling step, fuel supply to the engine is inhibited, and a camshaft is rotationally driven following upon activation of an engine-starting electrical machine. In this way, a pumping member associated to a tappet for actuating an intake valve is used as a pump for drawing fluid into the pressure chamber from an auxiliary fluid tank. During this step, a control valve is opened and closed in synchronism with movement of the pumping member so as to be open when the pumping member advances towards the pressure chamber and closed when the pumping member moves away from the pressure chamber.