Variable Force Engine Valve Actuation for Energy Efficiency
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Solution Overview
Problem
Hydraulic actuation systems for engine valves face challenges in immediate response and energy efficiency due to the need for high return spring force and pressure levels, which can result in energy consumption and vibration issues, especially in variable actuation systems that require precise control.
Innovation Solution
An auxiliary device is introduced to vary the force keeping the engine valve closed during its rotation cycle, using a solenoid, an auxiliary elastic element, or a hydraulic cylinder to reduce the force required for opening and maintain closure, allowing for lower pressure levels and improved responsiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high force return spring is used to ensure the engine valve remains closed, then the valve closure reliability is improved, but the energy consumption increases and the opening stage cannot be facilitated
Solution Approach 1:
The patent applies a variable return force mechanism where the return spring force is not constant but varies during the cam rotation cycle. The return force is higher when the valve should remain closed and reduced when opening is required, enabling the system to maintain reliability while reducing energy consumption during critical phases.
Solution Approach 2:
The invention implements periodic variation of the return spring force through cam profile design that modulates the spring compression. This periodic action creates high return force during closure-critical phases and reduced force during opening phases, resolving the contradiction between maintaining closure reliability and reducing energy consumption.
2Speed
If a high pressure level is maintained in the fluid volume to ensure immediate valve actuation, then the response time is improved, but the energy consumption increases
Solution Approach 1:
The patent employs dynamic pressure control where the fluid pressure is not maintained at a constant high level but varies according to operational requirements. The pressure is elevated during phases requiring immediate response and reduced during other phases, achieving fast actuation when needed while minimizing energy consumption overall.
3Reliability
If a high load return spring is used to keep the valve closed, then the valve remains securely closed during cam rotation, but vibrations and noise increase
Solution Approach 1:
The invention uses periodic modulation of the return spring force through cam profile design. The spring force is intensified during phases where secure closure is critical and attenuated during other phases, thereby maintaining valve stability when needed while reducing vibrations and noise during non-critical phases.
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 solution ensures reliable and precise actuation of engine valves with reduced energy consumption and minimized vibrations, enabling efficient operation across varying engine conditions without the need for high pressure levels.
Implementation Method 1
an auxiliary device for applying an additional force to the engine valve, tending to keep the engine valve in a closed position
Implementation Method 2
an auxiliary elastic element carried by a supporting structure that is fixed with respect to said engine valve during the movement of the engine valve
Implementation Method 3
a hydraulic cylinder including two cylinder elements slidably mounted with each other, and defining a cylinder chamber between them, and a spring tending to keep said cylinder elements in a position corresponding to a maximum elongation configuration of said cylinder chamber
Data Source
AI summary
An actuating system of an engine valve comprises a movable member, for example, in the form of a master piston controlled by a cam of a camshaft. A slave piston is hydraulically controlled by the master piston by means of a volume of pressurized fluid, to open said engine valve against the action of a return spring. The system also comprises an auxiliary device for applying an additional force to the engine valve to keep the engine valve in a closed position. The auxiliary device is configured or controlled in such a way that the total force tending to keep the engine valve in its closed position varies during each rotation cycle of the cam. The total force is higher at least in one part of the rotation cycle of the cam wherein the engine valve must remain in its closed position, and is, instead, reduced at least in one part of the rotation cycle of the cam wherein the engine valve is not in its closed position.