Variable Intake Valve Actuation for Engine Noise Reduction
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Solution Overview
Problem
Existing systems for variable actuation of engine intake valves experience excessive noise during partial engine loads due to rapid closing movements of the intake valves when uncoupled from their control cams, despite hydraulic braking, and air displacement contributes to noise generation.
Innovation Solution
An internal-combustion engine with an electrically actuated control valve having three operating positions (completely open, partially open, and completely closed) allows for adjustable speed control of the intake valve closing movement by varying the rate at which the pressure chamber is emptied, enabling slower valve closure at partial engine loads to minimize noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the pressure chamber is emptied rapidly to uncouple the intake valve from the cam, then the valve closes quickly improving responsiveness, but excessive noise is generated during partial engine loads
Solution Approach 1:
The control valve transitions from a static two-position design to a dynamic three-position design, enabling the system to adaptively select between fast closing (position 1), controlled closing (position 2), and closed (position 3) states based on real-time operating conditions such as engine load and speed, thereby optimizing the trade-off between responsiveness and noise
Solution Approach 2:
The invention changes the flow rate parameter of hydraulic fluid from the pressure chamber by introducing an intermediate partially open position of the control valve, allowing the system to modulate the closing speed of the intake valve according to operating conditions, reducing noise during partial loads while maintaining fast response when needed
2Device complexity
If a single electrically actuated control valve is used for each cylinder, then device complexity is reduced, but the ability to precisely control valve closing speed is limited
Solution Approach 1:
The control valve's opening is segmented into three distinct states (fully open, partially open, fully closed), allowing precise control of hydraulic fluid flow rate without requiring multiple separate valves, thus maintaining simplicity while enhancing control capability
Solution Approach 2:
The single control valve performs multiple functions by operating in three positions: it can fully open for rapid pressure chamber emptying, partially open for controlled emptying to reduce noise, and fully closed to maintain pressure, eliminating the need for separate valves for different closing speed requirements
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 adjustable closing speed of the intake valves reduces noise levels during partial engine loads by modulating the valve closure rate, enhancing operational quietness and efficiency.
Implementation Method 1
a pressurized-fluid chamber (C), facing which is a pumping plunger (16) connected to the tappet of the valve
Implementation Method 2
at least one intake valve and at least one exhaust valve associated to said intake and exhaust ducts and provided with respective return springs that push them towards a closed position
Implementation Method 3
a single, electrically actuated, control valve for each cylinder, adapted to set in communication said pressurized-fluid chamber with a discharge channel
Data Source
AI summary
An internal-combustion engine includes a system for variable actuation of intake valves, including a control valve for each cylinder, which controls communication of a pressurized-fluid chamber with a discharge channel. The control valve has at least three different positions, namely, a first completely open position, a second partially open position, and a third completely closed position. Electronic control means are programmed for keeping the control valve in its closed position in operating stages in which the intake valve must remain coupled to the respective cam and for bringing the control valve from its completely closed position to its partially open position or to its completely open position in operating stages in which the intake valve must be uncoupled from the respective cam, selection between the first position and said second position of the control valve being made as a function of one or more operating parameters of the engine.