Rotary Engine Journal Bearing Lubrication
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Solution Overview
Problem
Existing rotary engines face challenges in efficiently lubricating bearings and gear components, leading to reduced engine efficiency, increased vibration, and limited size due to the reliance on ball or needle bearings and the need for oil to be mixed with fuel, which results in unburned hydrocarbons and lowered fuel efficiency.
Innovation Solution
A rotary engine with an integrated lubricating unit that supplies oil directly to bearings and gear components through a journal bearing system, using an oil pan, oil pump, and oil supply passages, allowing for separate lubrication and oil circulation, reducing oil leakage and enhancing engine performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If ball bearing or needle bearing is used to support the crankshaft, then the engine structure remains compact, but the bearing is difficult to replace and has limited load support capability
Solution Approach 1:
The patent transitions from point-contact ball/needle bearings to surface-contact journal bearings, fundamentally changing the contact parameter from point to surface. This enables the bearing to be divided into upper and lower halves that can be separately installed and replaced, improving both load support capability and replaceability.
2Reliability
If oil is introduced into the air-fuel mixture for lubrication, then lubrication is provided, but oil is not supplied to portions where mixture is not provided and fuel efficiency decreases
Solution Approach 1:
The patent segments the lubrication system from the fuel injection system, creating a separate oil supply pathway through oil holes and oil passages. This ensures oil is delivered directly to bearing surfaces independent of fuel mixture distribution, achieving complete lubrication coverage without compromising fuel efficiency.
Solution Approach 2:
The patent introduces dedicated oil passages and oil holes as intermediary structures to transport lubricant directly to the bearing surfaces. This intermediary system ensures reliable oil supply to all lubrication points regardless of fuel mixture flow, solving the coverage problem while maintaining fuel efficiency.
3Reliability
If journal bearing is applied to increase engine size and improve reliability, then load support and reliability improve, but a separate lubrication system is required increasing complexity
Solution Approach 1:
The patent merges the lubrication system with the crankcase structure by forming oil passages and oil holes directly in the crankcase. This integration approach provides reliable journal bearing lubrication while minimizing system complexity, as the lubrication pathways are built into the existing structural component rather than added as separate systems.
4Strength
If bearing size is increased to improve load support, then reliability improves, but the engine size increases
Solution Approach 1:
The journal bearing structure utilizes the rotational motion of the crankshaft itself to generate hydrodynamic pressure within the oil film, eliminating the need for large bearing dimensions or external lubrication mechanisms. The bearing surfaces are designed to self-lubricate through the relative motion between the crankshaft journal and bearing, maintaining compact engine size while supporting high loads.
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 solution enables effective lubrication of bearings and gear components, increasing engine size and capacity, improving fuel efficiency, reducing unburned hydrocarbons, and extending bearing lifespan by providing a direct and controlled oil supply, while also reducing noise and vibration.
Implementation Method 1
an oil pump to pump up oil filled in the oil pan
Implementation Method 2
a journal bearing method, it is important to apply lubricant to a journal surface
Data Source
AI summary
A rotary engine having a crankshaft, a housing provided with lobe accommodating portions arranged to surround the crankshaft, and combustion chambers communicating with the lobe accommodating portions, a rotor rotatable eccentrically with respect to the crankshaft and provided with lobes continuously accommodated in the lobe accommodating portions, a housing cover provided with a bearing portion through which the crankshaft is inserted so as to be rotatably supported, and a lubricating unit to supply oil to the bearing portion, wherein the lubricating unit includes an oil pan to accommodate oil therein, an oil pump to pump up oil filled in the oil pan, and an oil supply passage having both ends located in the oil pump and the bearing portion, respectively, is provided. This structure may allow direct and effective lubrication of the bearing portion, and can employ a journal bearing.