Split Cycle Engine Shuttle Valve Pressure Loss Reduction
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Solution Overview
Problem
Conventional internal combustion engines face inefficiencies due to conflicting requirements for heat rejection during different strokes, leading to low fuel efficiency, incomplete combustion, and harmful emissions, with existing dual-piston and split-cycle engine configurations failing to effectively govern working fluid transfer without pressure loss and minimizing dead space between cylinders.
Innovation Solution
A bi-directional fluid flow split-cycle internal combustion engine with a single crossover valve and a shuttle mechanism that alternately couples and decouples compression, combustion, and expansion chambers, utilizing temperature-differentiated cylinders to enhance fuel energy conversion into mechanical work, and a phase shifting module to control piston phases for optimized operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional internal combustion engines use a single cylinder for all four strokes, then the engine structure is simple, but fuel efficiency is low due to heat rejection during compression and high temperature during intake
Solution Approach 1:
The engine is divided into separate compression and expansion cylinders, allowing independent thermal management for each function. The compression cylinder can be cooled efficiently while the expansion cylinder maintains higher temperature, resolving the heat rejection conflict and improving fuel efficiency
Solution Approach 2:
The patent introduces a temporal dimension to the thermal management problem by separating the four strokes across two cylinders that operate out of phase. This allows the compression cylinder to be cold during compression while the expansion cylinder is hot during power stroke, eliminating the need to compromise between conflicting thermal requirements in a single cylinder
2Loss of energy
If dual-piston split-cycle engine configurations are used to improve fuel efficiency, then energy loss is reduced, but dead space between cylinders increases and pressure loss occurs during fluid transfer
Solution Approach 1:
A crossover valve system acts as an intermediary mechanism between the compression and expansion cylinders. This valve carefully controls the transfer of working fluid at optimal pressure points, minimizing pressure loss and dead space effects while enabling the benefits of split-cycle operation
Solution Approach 2:
The engine timing is arranged so that the compression stroke completes and transfers charge to the expansion cylinder just before the expansion stroke begins. This preliminary action ensures maximum pressure is maintained during transfer, reducing energy loss from pressure drop and minimizing the impact of dead space
3Productivity
If conventional engines operate with high temperature in cylinder during intake and compression, then combustion is easier to initiate, but volumetric efficiency is reduced and piston work increases
Solution Approach 1:
By separating compression and expansion functions into different cylinders, the compression cylinder can be efficiently cooled to reduce temperature during intake and compression. This lowers the temperature penalty on volumetric efficiency and reduces the work required by the piston, while still enabling complete combustion in the expansion cylinder
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 improved fuel efficiency and power output by allowing flexible operation modes and maintaining high-pressure sealing, reducing gas leaks and dead space, thereby enhancing overall engine performance compared to conventional engines.
Implementation Method 1
a single crossover valve and a shuttle mechanism that alternately couples and decouples compression, combustion, and expansion chambers
Implementation Method 2
utilizing temperature-differentiated cylinders to enhance fuel energy conversion into mechanical work
Implementation Method 3
temperature-differentiated cylinders to enhance fuel energy conversion into mechanical work
Implementation Method 4
maintaining high-pressure sealing, reducing gas leaks
Data Source
AI summary
A split-cycle internal combustion engine (ICE) is provided, comprising a compression cylinder, an expansion cylinder and a crossover valve having a valve cylinder housing inside a shuttle and a combustion chamber structure defining a combustion chamber. The shuttle is configured to perform reciprocating motion inside the valve cylinder synchronously with a compression piston and an expansion piston, thereby alternatingly fluidly coupling and decoupling the combustion chamber with the compression cylinder and with the expansion cylinder, selectively. Sealing rings positioned between the valve cylinder and the shuttle prevent gas leaks between them during the reciprocating motion. In some embodiments, a phase shift between the pistons may be set or varied by a piston phase transmission gear. A bi-directional fluid flow split-cycle internal combustion engine (ICE) is also provided having a first cylinder, a second cylinder, a combustion chamber and a single crossover valve fluidly communicating them.