Engine Lubrication System Using Pressure Pulsations and Check Valves
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Solution Overview
Problem
Existing lubrication systems for two-stroke engines that mix lubricating oil with the intake mixture lead to oil deposition on engine surfaces, causing increased THC emissions, white smoke, and abnormal combustion, and require complex oil pumps, making them unsuitable for general-purpose engines.
Innovation Solution
A lubrication system that utilizes pressure pulsations in the crankcase chamber to recover and supply lubricating oil in mist form without a pump, using a network of passages and check valves to manage oil flow and mixing with intake air, allowing for efficient lubrication and oil recovery with a simple structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lubricating oil is injected into the intake passage in mist form using a pump, then the lubricating oil can be supplied to various parts of the engine, but the size and complexity of the engine increases
Solution Approach 1:
The invention extracts the pump component from the lubrication system and replaces it with a passive check valve mechanism. The oil pump is completely removed, and its function is replaced by utilizing the existing pressure pulsations in the crankcase chamber to drive oil flow through check valves, thereby simplifying the engine structure while maintaining reliable lubrication supply.
Solution Approach 2:
The system uses the engine's own operational characteristics (pressure pulsations during reciprocating movement) to drive the lubrication system. The pressure variations generated by the piston movement automatically open and close the check valves to pump oil without requiring an external power source or additional mechanical components.
2Reliability
If lubricating oil is injected into the intake passage in mist form, then lubrication is achieved, but oil is deposited on the wall surfaces of the intake passage causing increased THC emissions and abnormal combustion
Solution Approach 1:
The system recovers deposited oil from the intake passage wall surfaces before it can be sucked into the combustion chamber in substantial amounts. The check valves are positioned to capture oil that condenses or deposits on the intake passage walls during the suction stroke, preventing it from entering the combustion chamber and causing harmful emissions.
Solution Approach 2:
The invention implements an oil recovery mechanism where lubricating oil that deposits on the intake passage wall surfaces is collected and returned to the oil supply system through the check valve mechanism, rather than being discarded into the combustion chamber. This recycles the oil and prevents emission problems.
3Reliability
If an oil pump is used to supply lubricating oil, then adequate lubrication can be provided, but fuel economy deteriorates due to additional energy consumption
Solution Approach 1:
The lubrication system is made self-powered by utilizing the pressure pulsations that naturally occur during the engine's reciprocating operation. The check valves passively respond to these pressure variations, eliminating the need for an externally powered oil pump and the associated fuel consumption.
Solution Approach 2:
The active mechanical pump system is replaced with a passive valve-based mechanism that uses the engine's inherent pressure oscillations to drive oil flow. This substitution eliminates the energy-consuming mechanical pumping action while maintaining adequate lubrication supply.
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
The system effectively supplies lubricating oil to engine parts, recovers deposited oil, and reduces emissions by eliminating the need for a pump, improving fuel economy and simplifying engine design.
Implementation Method 1
a pressure in a crankcase chamber (2A) pulsates owing to a reciprocating movement of a piston (23) in a cylinder (22)
Implementation Method 2
The gas in the gas phase part of the oil tank is pressurized by the pressure in the crankcase chamber to be pumped toward the intake passage via the second passage
Implementation Method 3
the lubricating oil in the liquid phase part is placed under pressure from the gas phase part, and is fed to the second passage via the third passage
Implementation Method 4
As the lubricating oil is mixed with the gas under pressure at the connecting part between the second passage and the third passage, the lubricating oil is atomized, and oil mist is produced
Implementation Method 5
a first check valve (69) provided in the first passage to permit a flow from the crankcase chamber to the oil tank but not in a reverse direction
Data Source
AI summary
A lubrication system for an engine is provided which includes an oil tank, a first passage communicating a bottom part of the crankcase chamber with an upper part of the oil tank, a first check valve provided in the first passage to permit a flow from the crankcase chamber to the oil tank but not in a reverse direction, a second passage communicating an upper part of the oil tank with an upper part of the crankcase chamber, a second check valve provided in the second passage to permit a flow from the oil tank to the crankcase chamber but not in a reserve direction and a third passage communicating a lower part of the oil tank with the second passage.