Continuous Variable Valve Lift Mechanism for Engine Fuel Efficiency
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Solution Overview
Problem
Existing engine technologies face challenges in optimizing fuel consumption and engine output due to fixed intake and exhaust valve lift values, which do not adapt effectively to varying engine operation states, particularly in low load conditions.
Innovation Solution
A continuous variable valve lift device that differentiates the valve lift values of two intake valves using a rotatable input shaft, input cam, control shaft, and output rockers with distinct control long holes, allowing for independent control of valve lift based on engine operation, enhancing flowability and fuel efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If fixed cam profiles are used for intake valves, then the structure is simple, but the fuel consumption cannot be optimized in varying engine operation states
Solution Approach 1:
The patent implements a dynamic valve lift control system where the camshaft can rotate relative to the crankshaft to continuously vary the valve lift profile. The camshaft rotation angle is adjusted according to engine operating conditions, transforming the fixed lift mechanism into a dynamic one that adapts to different load and speed conditions, thereby optimizing fuel consumption across the operating range.
Solution Approach 2:
The system changes the valve lift parameter continuously by rotating the camshaft to different angular positions. By varying the camshaft rotation angle relative to the crankshaft, the effective lift profile changes, allowing optimization of intake flow and fuel combustion efficiency for different engine operating states without requiring multiple fixed cam profiles.
2Use of energy by moving object
If unequal valve lift control is implemented for two intake valves, then fuel consumption improves in low load range, but the device structure becomes more complex
Solution Approach 1:
The patent divides the valve train into two independent control paths, one for each intake valve. Each valve has its own rocker arm and spring assembly, allowing independent lift control. The first intake valve can be given a larger lift than the second intake valve in low load conditions, optimizing the air-fuel mixture flow and combustion efficiency without requiring a completely separate control mechanism for each valve.
Solution Approach 2:
The system employs asymmetric valve lift profiles where the two intake valves have different lift values optimized for different functions. One valve is designed with higher lift for better flow at certain conditions, while the other has lower lift for optimal combustion, creating an asymmetric configuration that improves overall engine efficiency in low load operation.
3Power
If continuous variable valve lift control is implemented, then engine output increases, but the reliability of operation may decrease due to complex mechanisms
Solution Approach 1:
The continuous variable valve lift mechanism uses a dynamically adjustable camshaft rotation system with controlled clearances and preloaded springs. The variable clearance mechanism allows smooth transition between different lift ranges while maintaining reliable operation through proper mechanical design of the adjustment components, ensuring consistent performance across the full operating range.
Data Source
AI summary
A continuous variable valve lift device includes a rotatable input shaft, an input cam rotating with the input shaft, a control shaft rotatably disposed parallel to the input shaft, an input rocker mounted to, and rotatable round, the control shaft so as to be in contact with the input cam to have a torque forwarded thereto from the input cam, a control link mounted to the control shaft eccentrically, an input link having one end connected to the input rocker, a connecting rod connected between the other end of the input link and the control link, and a valve operating unit mounted to rotate as one unit with the control shaft for operating the valve, the valve operating unit having a control long hole for movably inserting the connecting rod therein, for improving the fuel consumption at a low load operation range of the engine.