Variable Valve Timing Oil Passage Layout for Pressure Stability
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Solution Overview
Problem
Internal combustion engines experience hydraulic pressure insufficiency in variable valve timing mechanisms due to oil leakage, leading to reduced efficiency and potential inoperability of the oil jet and variable valve timing mechanisms.
Innovation Solution
The configuration of oil passages and control valves is optimized such that the connection passage supplying oil to the variable valve timing mechanism with greater oil leakage is located downstream, ensuring higher hydraulic pressure is maintained for the mechanism with lesser leakage, and the oil control valve is positioned centrally to enhance responsivity but increase leakage, thereby managing oil leakage effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the connection passage to the variable valve timing mechanism with greater oil leakage is placed upstream, then easier oil supply is achieved, but hydraulic pressure insufficiency occurs in the downstream mechanism
Solution Approach 1:
The patent applies local quality by differentiating the oil supply arrangement for each variable valve timing mechanism based on its specific leakage characteristics. The connection passage for the mechanism with greater leakage (intake side) is positioned downstream, while the connection passage for the mechanism with lesser leakage (exhaust side) is positioned upstream. This localized optimization ensures that each mechanism receives appropriate hydraulic pressure despite differences in their leakage rates.
Solution Approach 2:
The patent changes the spatial arrangement parameter of the connection passages in the oil passage system. By switching from a uniform upstream connection arrangement to a differentiated arrangement where one connection is upstream and another is downstream based on leakage characteristics, the system maintains adequate hydraulic pressure for both mechanisms while accounting for their different oil leakage rates.
2Speed
If the oil control valve is positioned centrally in the variable valve timing mechanism, then responsivity is improved, but oil leakage increases
Solution Approach 1:
The patent converts the harmful effect of increased oil leakage from the centrally positioned oil control valve into a beneficial lubrication effect. The leaked oil is directed to lubricate the cam sprocket and timing chain, reducing wear on these components. This transforms what would normally be a loss into a useful function that benefits another part of the system.
3Ease of manufacture
If oil leakage from variable valve timing mechanisms is increased, then lubrication of cam sprockets is improved, but hydraulic pressure insufficiency worsens
Solution Approach 1:
The patent applies local quality by selectively positioning connection passages at different locations (upstream vs. downstream) based on the specific leakage characteristics of each variable valve timing mechanism. The mechanism with greater leakage (intake side) receives oil from the downstream connection, while the mechanism with lesser leakage (exhaust side) receives oil from the upstream connection. This localized differentiation maintains hydraulic pressure while allowing beneficial leakage for lubrication.
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 configuration limits hydraulic pressure insufficiency in the downstream variable valve timing mechanisms, maintains proper operation of the oil jet, and reduces wear on cam sprockets by effectively utilizing leaked oil for lubrication, thus improving the engine's responsiveness and preventing mechanism inoperability.
Implementation Method 1
Oil pumped by an oil pump is supplied from the main oil passage of the cylinder head
Implementation Method 2
changes an opening/closing timing of an exhaust valve by supply and drainage of oil
Implementation Method 3
reduces wear on cam sprockets by effectively utilizing leaked oil for lubrication
Data Source
AI summary
An internal combustion engine includes exhaust-side and intake-side variable valve timing mechanisms, an oil passage defined in the cylinder head, an exhaust-side connection passage that branches from the oil passage to conduct oil to the exhaust-side variable valve timing mechanism, and an intake-side connection passage that branches from the oil passage to conduct oil to the intake-side variable valve timing mechanism. The connection passage that conducts oil to one of the exhaust-side variable valve timing mechanism and the intake-side variable valve timing mechanism that has a greater amount of oil leakage when oil having the same pressure is supplied to the variable valve timing mechanisms to operate the variable valve timing mechanisms is located at a downstream side in the oil passage of the connection passage that conducts oil to the variable valve timing mechanism that has a smaller amount of oil leakage.