Opposed Piston Engine Offset Crankshafts In-Phase Timing
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Solution Overview
Problem
Conventional opposed piston engines require crankshaft phase shifts and exhaust/inlet port valves, leading to increased stresses, reverse torsional losses, and complexity, which can be costly and prone to breakage.
Innovation Solution
The opposed piston engine operates with the inlet and exhaust piston crankshafts rotating in phase, eliminating the need for phase shifts and valves by synchronizing the movement of the pistons to close the exhaust port before the inlet port, reducing stress and complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a crankshaft phase shift is provided so that the inlet piston movement lags the exhaust piston movement, then the inlet port opens after the exhaust port has opened (reducing blowback), but reverse torsional losses increase as the inlet piston moves toward top dead center against expanding combustion gases and engine components are subjected to increased stresses
Solution Approach 1:
Instead of using a crankshaft phase shift to sequence port opening (conventional approach), the patent inverts the approach by using offset crankshaft axes with in-phase rotation. The offset positioning of the crankshaft axes relative to the cylinder centerline naturally sequences the port opening timing through the piston geometry and connection rod arrangement, eliminating the need for phase shifting while avoiding reverse torsional losses.
2Object-generated harmful factors
If a crankshaft phase shift is provided to sequence port opening, then blowback is reduced, but engine components are subjected to increased stresses necessitating strong, typically heavy components
Solution Approach 1:
The patent inverts the conventional approach by eliminating crankshaft phase shift and instead using offset crankshaft axes with in-phase rotation. This configuration reduces stress on engine components by avoiding the out-of-phase piston movements, allowing for lighter component designs while still achieving proper port sequencing through the offset geometry.
3Ease of operation
If an exhaust port valve and/or inlet port valve is provided to control port opening and closing timing, then desired timing is achieved without crankshaft phase shift, but device complexity increases and additional equipment subject to breakage is introduced
Solution Approach 1:
The patent extracts and eliminates the exhaust port valve and inlet port valve from the engine system. By using offset crankshaft axes with in-phase rotation, the natural piston movement geometry achieves the desired port timing without requiring additional valve mechanisms, thereby reducing device complexity and eliminating potential points of failure.
Solution Approach 2:
The offset crankshaft configuration enables the pistons themselves to control port opening and closing timing through their natural reciprocating motion, without requiring separate valve actuation systems. The engine mechanism serves its own timing control function through the geometric relationship between the offset crankshafts and cylinder ports.
Data Source
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AI summary
In an opposed piston engine, an inlet piston crankshaft axis and an exhaust piston crankshaft axis both ex tend parallel to a central cylinder plane extending through a centerpoint of a cylinder of the engine and along a central axis of the cylinder. The inlet piston crankshaft axis and the exhaust piston crankshaft axis are both offset from the central cylinder plane. The inlet piston and the exhaust piston linked to the inlet piston crankshaft and the exhaust piston crankshaft are arranged so that the inlet piston closes an inlet port as the inlet piston moves from its bottom dead center toward its top dead center at substantially a same time as the exhaust piston closes the exhaust port as the exhaust piston moves from its bottom dead center toward its top dead center.