Variable Oscillating Cam Valve Actuation
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Solution Overview
Problem
Current variable valve actuation (VVA) systems, particularly hydraulic ones, suffer from inefficiency which increases brake specific fuel consumption (BSFC) and mechanical systems have limited flexibility and engine architecture capabilities.
Innovation Solution
A high-efficiency variable valve actuation system utilizing a variable oscillating cam mechanism with an intermediate lever and cam phasers to enable various valve timing, lift, and duration control, allowing for early or late intake and exhaust valve events, and independent lift of intake valves, integrated with a bi-directional rotatable pivot control shaft and rocker arm appendages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If hydraulic VVA systems are used to achieve variable valve actuation functionality, then valve timing control is improved, but brake specific fuel consumption increases by 1-3% due to energy loss
Solution Approach 1:
The patent replaces the hydraulic actuation system with a purely mechanical variable oscillating cam system. The cam profile geometry directly controls valve timing and lift without requiring hydraulic fluid pressure, eliminating the energy losses associated with hydraulic pumps, fluid compression, and leakage. The mechanical cam-follower arrangement maintains valve control functionality while significantly improving fuel efficiency.
Solution Approach 2:
The variable oscillating cam mechanism serves multiple functions simultaneously: it controls valve timing, valve lift, and valve duration through a single integrated mechanical structure. The cam profile can be designed to provide different valve events (early intake closure, late exhaust opening, etc.) without requiring separate hydraulic actuators for each function, reducing overall system complexity and energy consumption.
2Loss of energy
If conventional mechanical VVA systems are used to maintain high efficiency, then fuel consumption is reduced, but engine architecture flexibility and capability are limited
Solution Approach 1:
The patent employs a variable oscillating cam mechanism where the cam profile can dynamically adjust its effective geometry through a controlled oscillation or rotation of the cam shaft relative to the follower. This dynamic adjustment allows the same mechanical system to provide different valve timing and lift characteristics for various engine operating conditions and architectures, greatly enhancing adaptability while maintaining mechanical efficiency.
Solution Approach 2:
The valve actuation system is segmented into independent controllable elements through the variable oscillating cam approach. Each cylinder or valve train can potentially have independent cam oscillation control, allowing for cylinder deactivation, selective valve timing adjustment, and compatibility with different engine configurations (inline, V-type, rotary) without requiring a complete redesign of the mechanical actuation system.
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 and aftertreatment performance by optimizing valve actuation regimes, improving fuel efficiency, and expanding engine architecture applicability while reducing fuel consumption and emissions.
Implementation Method 1
The camshaft includes a first cam. The control shaft includes a second cam. The valve actuation system is adapted to be driven by the first cam and the second cam.
Implementation Method 2
The intermediate arm is adapted to oscillate by the action of the first cam about a first pin.
Implementation Method 3
The first rocker is rotatably positioned on the control shaft and includes a foot at a first end and a second roller at a second end opposite the first end. The foot causes movement of the valve by the action of the first cam.
Data Source
AI summary
A high-efficiency mechanism for variable valve actuation with increased engine architecture applicability is described. The high efficiency mechanism introduces an intermediate lever having a secondary cam profile forming a variable oscillating cam between a rotating camshaft and a rocker arm.