Four-Stroke Engine Oil Groove Pressure Pulsation Lubrication
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Solution Overview
Problem
Existing lubricating structures for four-stroke engines require a dedicated check valve to return surplus lubricating oil from the valve chamber to the crank chamber, which hinders the flow of lubricating oil mist and necessitates a dedicated supply line, complicating the lubrication of the valve driving mechanism.
Innovation Solution
A lubricating structure with a first oil groove for introducing mist from the crank chamber to the valve chamber and a second oil groove with a larger cross-sectional area for returning surplus oil to the crank chamber, utilizing pressure pulsations to facilitate oil flow without a dedicated part, such as a check valve.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a check valve is installed to return surplus lubricating oil from the valve chamber to the crank chamber, then the surplus oil can be returned properly, but the check valve hinders the flow of lubricating oil mist and requires a dedicated supply line, increasing device complexity
Solution Approach 1:
The patent removes the check valve from the system and extracts only the necessary oil return function through a simplified groove structure. The second groove provides the oil return path without requiring a dedicated check valve, thereby eliminating the complexity while maintaining the surplus oil return capability.
Solution Approach 2:
The first groove serves multiple functions: it supplies lubricating oil mist to the valve chamber during normal operation and also allows surplus oil to return to the crank chamber when pressure differential reverses. This multi-functional groove design eliminates the need for separate dedicated components for oil supply and return.
2Reliability
If a dedicated lubricating oil supply line is installed to forcibly lubricate the valve driving mechanism, then reliable lubrication is achieved, but the device complexity increases
Solution Approach 1:
The lubrication system uses the engine's own pressure pulsations to automatically regulate oil flow. During compression stroke, positive pressure forces oil mist through the first groove to lubricate the valve mechanism; during intake stroke, negative pressure allows surplus oil to return through the second groove. This self-regulating mechanism eliminates dedicated supply lines and external control systems.
Solution Approach 2:
The patent utilizes the periodic pressure pulsations inherent in the four-stroke engine cycle to control oil flow direction. The alternating positive and negative pressure phases naturally drive oil mist into the valve chamber during compression and allow return flow during intake, providing periodic lubrication without complex continuous supply systems.
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
Effectively returns surplus lubricating oil to the crank chamber, ensuring reliable lubrication of the valve driving mechanism and preventing oil mist from entering the intake port, thus maintaining efficient engine operation without the need for a dedicated check valve.
Implementation Method 1
Reciprocating motion of a piston causes pressure in the crank chamber to pulsate by alternating positive pressure and negative pressure
Implementation Method 2
the pressure in the valve chamber causes a pulsation difference such as a pulsation delay (phase difference) or amplitude reduction (amplitude difference) with respect to the pressure in the crank chamber and results in a state of being higher than the pressure in the crank chamber
Data Source
AI summary
A lubricating structure for a four-stroke engine includes a first oil groove and a second oil groove. The engine includes a crankcase, a cylinder, a cylinder head and an oil pan. The crankcase makes up a crank chamber. The cylinder head is equipped with a valve chamber housing valve driving mechanism. The oil pan is provided on a bottom of the crank chamber. The first oil groove leads mist of the lubricating oil in the crank chamber to the valve chamber by communicating the crank chamber and the valve chamber with each other. The second oil groove leads surplus lubricating oil in the valve chamber to the oil pan in the crank chamber by communicating a lower part of the valve chamber with a neighborhood of the oil pan in the crank chamber. The first oil groove is set smaller in flow path cross-sectional area than the second oil groove.