Trochoid Pump Lubrication for Multi-Orientation Four-Cycle Engines
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Solution Overview
Problem
Small four-cycle internal combustion engines used in portable and transportable power tools face challenges with weight, emissions, and lubrication, particularly when operating in various orientations, as traditional lubrication systems are not effective for horizontal or vertical power shaft configurations.
Innovation Solution
A lightweight four-cycle engine design with an overhead valve train and a lubrication system that uses a trochoid pump to splash oil mist into the crankcase and valve chamber, allowing the engine to operate in a wide range of orientations without additional check valves, and features a return system for lubricant oil to re-enter the reservoir after lubrication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a traditional lubrication system is used in a four-cycle engine, then the engine structure is simple, but the engine cannot operate in various orientations (vertical, horizontal, inverted) without additional check valves and complex lubrication pathways
Solution Approach 1:
The patent inverts the traditional lubrication approach by using a trochoid pump driven by the camshaft to actively deliver oil to all engine components, rather than relying on gravity and oil galleries. This active delivery system works in any orientation, eliminating the need for check valves and complex lubrication pathways that would be required to adapt traditional systems for multi-orientation operation.
Solution Approach 2:
The trochoid pump serves multiple functions: it delivers oil to the cylinder walls, piston, and crankshaft bearings simultaneously, and operates effectively regardless of engine orientation. This multi-functional component replaces what would otherwise require multiple orientation-specific lubrication pathways and check valves, simplifying the overall system while expanding operational versatility.
2Object-generated harmful factors
If a four-cycle engine is used instead of a two-cycle engine, then emissions are reduced, but the engine becomes heavier and more complex
Solution Approach 1:
The patent merges the lubrication function with the valve train operation by using the camshaft's rotational motion to drive the trochoid pump. This integration eliminates the need for a separate lubrication pump motor or additional drive mechanism, reducing overall engine weight and complexity while maintaining the emission benefits of four-cycle operation.
Solution Approach 2:
The camshaft, which already rotates as part of the valve train mechanism, is used to self-drive the lubrication pump through the trochoid mechanism. This self-service approach eliminates the need for external power sources or additional complex drive systems, keeping the engine lightweight while achieving effective lubrication in any orientation.
3Reliability
If a trochoid pump is used to deliver oil in any orientation, then lubrication effectiveness is maintained across all orientations, but the pump adds weight and complexity
Solution Approach 1:
The trochoid pump uses dynamic geometry where the pump elements rotate eccentrically within the pump housing, creating variable volume chambers that naturally draw in and discharge oil. This dynamic mechanism, driven by the camshaft's rotation, provides reliable lubrication in any orientation without requiring complex control systems, orientation sensors, or multiple pump configurations.
Solution Approach 2:
The patent replaces complex electronic or mechanically-controlled lubrication systems with a purely mechanical trochoid pump driven by the camshaft. This mechanical substitution eliminates the need for electronics, sensors, or complex control mechanisms, achieving reliable lubrication across all orientations with minimal added complexity.
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 engine achieves low emissions and is lightweight enough for hand-held use, maintaining effective lubrication across various orientations without additional weight or complexity, and provides improved cooling performance compared to traditional dry sump systems.
Implementation Method 1
A pump is connected drivably to said cam gear-cam assembly, said pump inhales lubrication oil from the oil reservoir and valve chamber to splash oil into the cylinder
Data Source
AI summary
The present invention is directed to a four-cycle engine including a lightweight aluminum alloy engine block having a cylindrical bore and an oil reservoir formed therein. A crankshaft is rotatably mounted in the engine block for rotation about a crankshaft axis. A piston reciprocates within the bore and is connected to the crankshaft by a connecting rod. An oil pump driven by the cam gear, which mates with a crank gear that is driven by a crank shaft, inhales oil from the oil reservoir and the valve chamber to splash lubricate into the cylinder bore. The engine is provided with a cylinder head assembly defining a compact combustion chamber having a pair of overhead intake and exhaust ports and cooperating intake and exhaust valves and a circular arc wall which surrounds around webs of the crankshaft so that each crankshaft web splashes and causes the oil to fly to lubricate engine parts.