Variable Valve Actuation with Constant Lift Cam Profile
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing multi-cylinder internal combustion engines face challenges in achieving better performance, lower consumption, and reduced pollutant emissions, particularly in petrol and diesel engines, due to limitations in valve operation systems.
Innovation Solution
The cam controlling each intake valve is designed to generate a lift profile with a substantially constant lift boot portion, combined with a variable valve operating system that adjusts solenoid valve operation based on engine speed and conditions, allowing for optimized overlap of intake and exhaust phases and reducing pollutant emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional valve operating system is used, then the structure is simple, but engine performance is limited and pollutant emissions are high
Solution Approach 1:
The patent implements a variable valve operating system that can dynamically adjust valve lift profiles and timing based on engine operating conditions. The system uses electronic control means to vary the time and extension of valve opening, allowing optimization of engine performance across different operating points while managing complexity through programmable control rather than mechanical complexity
Solution Approach 2:
The patent changes key parameters of valve operation including lift profile, opening time, and closure timing. By electronically controlling solenoid valves to vary these parameters, the system optimizes engine performance, reduces consumption, and lowers pollutant emissions without requiring fundamental structural redesign
2Productivity
If valve opening time is extended to improve scavenging, then air intake is enhanced, but effective compression ratio decreases
Solution Approach 1:
The system dynamically adjusts valve closure timing based on engine operating conditions. At low speeds and high loads, the system extends valve overlap to improve scavenging. At high speeds, it reduces overlap to maintain effective compression ratio, optimizing both parameters across the operating range
Solution Approach 2:
The electronic control system periodically adjusts valve timing parameters based on engine operating phase. The solenoid valves are controlled to vary valve lift profiles in periodic cycles, allowing the engine to optimize scavenging at appropriate moments while maintaining compression ratio when needed
3Power
If intake valve closes early to maintain compression ratio, then power is improved, but scavenging effect is reduced
Solution Approach 1:
The variable valve operating system dynamically adjusts closure timing based on real-time engine conditions. At high speeds, it closes the intake valve early to maintain compression ratio and power output. At low speeds and high loads, it delays closure to improve scavenging effect, optimizing the trade-off across operating conditions
4Productivity
If variable actuation system is implemented to optimize performance, then engine efficiency improves, but device complexity increases
Solution Approach 1:
The patent replaces complex mechanical valve timing mechanisms with an electronic control system. Electronic control means and solenoid valves replace traditional mechanical linkages, allowing software-based optimization of valve operation while reducing mechanical complexity and enabling flexible adjustment of lift profiles and timing
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 enhances engine performance, reduces pollutant emissions, and improves scavenging effects in petrol engines, while in diesel engines, it delays intake valve closure to reduce effective compression ratio, thereby decreasing smoke and nitrogen oxide emissions.
Implementation Method 1
a pumping piston (16) capable of transmitting a force to the stem of the valve (7), in such a manner as to cause the opening of the latter against the action of the spring means (9), through fluid under pressure (preferably oil from the engine lubrication circuit) present in a pressure chamber (C) which faces the pumping piston (16)
Implementation Method 2
said chamber of fluid under pressure being adapted to be connected through a solenoid valve (24) to a discharge channel (23), in order to uncouple the variable actuation valve from its respective tappet and to cause the rapid closure of the valve under the action of its respective biasing spring means
Implementation Method 3
at least one camshaft, for operating the intake valves and the exhaust valves of the cylinders of the engine, through respective tappets
Data Source
AI summary
An internal combustion engine is equipped with a variable actuation system for the intake valves, including a chamber of fluid under pressure interposed between the intake valve and the respective controlling cam, and a solenoid valve whose opening causes the pressure chamber to discharge such as to determine the rapid closure of the valve by effect of the respective biasing spring means, even when the respective cam would tend to keep the valve open. The variable valve operation system is used in combination with the use of cams controlling the intake valves shaped in such a manner as to give rise to an intake valve lift profile including a boot portion at substantially constant lift.