Moving Cam Variable Valve Lift for Engine Operation Area
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Solution Overview
Problem
Existing variable valve lift systems for internal combustion engines fail to adequately address expansion of operation area, accurate combustion control, reduction of NOx emissions, and combustion noise improvement, especially in engines with homogeneous mixture compression ignition.
Innovation Solution
A multiple variable valve lift apparatus with a moving cam system, including multiple cams and an operating unit controlled by a solenoid, allows for varying valve lift by selectively guiding cam protrusions to achieve underlap, rebreathing, and long duration operations, enhancing valve timing and lift for improved engine efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an ordinary variable valve lift apparatus is used, then valve lift can be varied depending on RPM, but expansion of operation area, accurate combustion control, reduction of NOx, and combustion noise improvement cannot be satisfied
Solution Approach 1:
The camshaft is divided into multiple independent cams (first cam, second cam, third cam) that can be selectively engaged. Each cam provides a different valve lift profile, allowing the system to segment the valve operation into distinct modes (e.g., high lift, low lift, intermediate lift) to expand the operation area without requiring a completely complex new system architecture.
Solution Approach 2:
The valve lift system dynamically switches between different cam profiles based on operating conditions. The movable cam follower can shift axially to engage different cams on the camshaft, enabling real-time adaptation of valve lift characteristics to expand the operational range of the engine across different RPM and load conditions.
2Manufacturing precision
If multiple cams are introduced to achieve multiple valve lifts, then combustion control accuracy improves, but the structure becomes more complex
Solution Approach 1:
Multiple cam profiles are merged into a single camshaft assembly, with each cam positioned at different axial locations. The movable cam follower integrates the function of selecting between multiple valve lift profiles, combining what could be separate systems into one unified structure that achieves precise combustion control through selective cam engagement.
Solution Approach 2:
The camshaft serves multiple functions by incorporating different cam profiles that can be selectively engaged. Instead of requiring separate camshafts or complex mechanisms for each valve lift mode, this universal camshaft design provides multiple valve lift characteristics (high lift, low lift, intermediate lift) through a single multi-functional component.
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 solution effectively expands the engine's operation area, achieves accurate combustion control, reduces NOx emissions, and improves combustion noise, leading to better fuel efficiency and engine performance.
Implementation Method 1
The operating unit may include a solenoid operated by the controller and a guide part, in which the cam guide protrusion is inserted, selectively protruded depending on an operation of the solenoid so as to guide the cam guide protrusion.
Data Source
AI summary
A multiple variable valve lift apparatus disposed at an intake part and an exhaust part of an engine includes: a moving cam rotating together with a camshaft, being movably disposed in an axial direction of the camshaft, and forming a plurality of cams for realizing valve lift to be different from each other and a cam guide protrusion; an operating unit selectively guiding the cam guide protrusion so as to move the moving cam in an axial direction of the camshaft; a controller controlling an operation of the operating unit; and a valve opening/closing unit opened/closed by contacting any one among the plurality of cams.