Variable Valve Gear Intake Timing Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing variable valve gear systems for internal combustion engines face challenges in optimizing fuel efficiency during both low-load and high-load operations, as advancing the intake valve closing timing to reduce negative pressure and pumping loss at low loads can lead to knocking at high loads, compromising fuel efficiency.
Innovation Solution
A variable valve gear system that dynamically controls the intake valve's opening and closing timings using a combination of a camshaft phase change mechanism and a variable valve lift mechanism, advancing the closing timing below a predetermined range at low loads and delaying it beyond the bottom dead center at high loads to mitigate knocking and improve fuel efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the closing timing of the intake valve is advanced during low-load operation, then negative pressure in the intake manifold is reduced and pumping loss is mitigated, but during high-load operation this timing advancement causes the actual compression ratio to become excessively high leading to knocking
Solution Approach 1:
The patent applies dynamics by making the valve timing adjustable rather than fixed. The variable valve timing mechanism allows the closing timing of the intake valve to be dynamically changed based on operating conditions (low-load vs. high-load operation), enabling the system to optimize performance across different operating ranges without suffering from the trade-off of a fixed timing setting
Solution Approach 2:
The patent changes the timing parameter of the intake valve closing event based on load conditions. During low-load operation, the closing timing is advanced to reduce pumping loss, while during high-load operation, the closing timing is delayed to prevent excessive compression ratio and knocking. This parameter adjustment resolves the contradiction by adapting the timing to operational requirements
2Object-affected harmful factors
If the closing timing of the intake valve is delayed during high-load operation to prevent knocking, then fuel efficiency is improved, but during low-load operation this delayed timing increases negative pressure and pumping loss
Solution Approach 1:
The variable valve timing mechanism enables dynamic adjustment of the intake valve closing timing based on real-time operating conditions. The system transitions from a static timing setting to a dynamic one, allowing optimization for both low-load (advanced timing) and high-load (delayed timing) operations, thereby resolving the energy loss contradiction
Solution Approach 2:
The timing parameter is varied according to load conditions to optimize performance. Advanced timing is used during low-load operation to minimize pumping loss, while delayed timing is applied during high-load operation to prevent knocking. This conditional parameter change resolves the contradiction between energy efficiency and knocking prevention
3Device complexity
If a fixed valve timing is used, then the mechanism is simple, but it cannot optimize fuel efficiency for both low-load and high-load operations simultaneously
Solution Approach 1:
The patent transitions from a fixed valve timing mechanism to a variable one, accepting increased complexity in exchange for the ability to optimize fuel efficiency across the entire operating range. The dynamic adjustment capability allows the system to achieve superior fuel economy by adapting timing to specific operating conditions
Solution Approach 2:
The variable valve timing mechanism serves multiple functions: it optimizes fuel efficiency during low-load operation by advancing timing, prevents knocking during high-load operation by delaying timing, and maintains compatibility with existing engine architectures. This multi-functionality justifies the added complexity
Data Source
AI summary
In a variable valve gear for an internal combustion engine provided with a camshaft phase change mechanism for variably controlling opening and closing timings of an intake valve, the camshaft phase change mechanism and a variable valve lift mechanism are controlled so that the closing timing of the intake valve is advanced beyond a predetermined range T1 including a bottom dead center when a load L of the internal combustion engine is less than a first predetermined value L1 and that the closing timing of the intake valve is delayed beyond the predetermined range T1 when the load L of the internal combustion engine is not less than the first predetermined value L1.