Two-Stroke Engine Lubrication System Using Pressure Pulsation
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Solution Overview
Problem
Existing two-stroke engines face challenges with lubrication systems that require an oil pump, increasing engine size and complexity, and result in lubricating oil deposition on intake passage walls, leading to increased THC emissions, white smoke, and abnormal combustion when lubricating oil is mixed with the intake in mist form.
Innovation Solution
A lubrication system that utilizes pressure pulsation from the crankcase chamber to recover and supply lubricating oil in mist form to engine parts without a pump, using a network of check valves and passages to manage oil flow and prevent reverse flow, allowing for efficient lubrication and oil recovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lubricating oil is injected into the intake passage in mist form, then various sliding parts of the engine are lubricated, but the lubricating oil is deposited on the wall surfaces of the intake passage and causes increased THC emissions, white smoke, and abnormal combustion
Solution Approach 1:
The patent implements an oil recovery system where deposited lubricating oil on intake passage walls is collected and returned to the carburetor for re-vaporization and re-injection. This closed-loop system recovers oil that would otherwise be wasted or cause harmful emissions, converting a harmful byproduct into a useful resource for continuous lubrication.
Solution Approach 2:
The system establishes a feedback mechanism where the amount and condition of deposited oil is continuously monitored (through the oil sensor) and this information is used to regulate the oil injection process. The recovered oil is fed back into the system to maintain optimal lubrication levels while preventing excessive deposition that would cause emissions problems.
2Reliability
If an oil pump is used to supply lubricating oil, then adequate lubrication is achieved, but the size and complexity of the engine increases
Solution Approach 1:
The patent employs a self-service lubrication system where the engine's own operating conditions (intake manifold vacuum, oil deposition on walls, temperature variations) are utilized to automatically pump, vaporize, and distribute lubricating oil without requiring an external oil pump. The system uses the engine's natural cycles to drive oil recovery and redistribution, eliminating the need for additional mechanical pumping components.
Solution Approach 2:
The patent replaces the traditional mechanical oil pump system with a vaporization-based distribution system. Instead of using mechanical force to pump and distribute oil, the system uses thermal energy to vaporize oil and the resulting vapor pressure differentials to distribute it throughout the intake system, substituting a mechanical solution with a thermal-fluid approach.
3Reliability
If lubricating oil is mixed with fuel and injected into intake air, then lubrication is achieved, but oil deposition on intake passage walls occurs
Solution Approach 1:
The patent implements an oil recovery system where deposited lubricating oil on intake passage walls is collected and returned to the carburetor for re-vaporization and re-injection. This closed-loop system recovers oil that would otherwise be wasted or cause harmful emissions, converting a harmful byproduct into a useful resource for continuous 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
The system effectively supplies lubricating oil to engine parts in mist form, reducing emissions and combustion issues by using pressure pulsation for oil recovery and distribution, eliminating the need for a pump and simplifying the engine structure.
Implementation Method 1
a pressure in an internal space (60) including a crankcase chamber (2A) thereof pulsates owing to a reciprocating movement of a piston in a cylinder
Implementation Method 2
a first check valve (69) provided in the first passage to permit a flow from the internal space to the oil tank but not in a reverse direction
Implementation Method 3
a flow regulator valve (82) provided in a part of the third passage located between the third check valve and the second passage for regulating a flow of lubricating oil flowing through the third passage
Data Source
AI summary
An internal combustion engine having an internal space including a crankcase chamber includes an oil tank, a first passage communicating a lower part of the internal space with a gas phase part of the oil tank, a first check valve provided in the first passage to permit a flow from the internal space to the oil tank, a second passage communicating the gas phase part with the internal space, a second check valve provided in the second passage to permit a flow from the second passage to the internal space, a third passage communicating a liquid phase part of the oil tank with the second passage, a third check valve provided in the third passage to permit a flow from the oil tank to the second passage, and a flow regulator valve provided in the third passage for regulating a flow of lubricating oil flowing through the third passage.