Planetary Piston Engine Layout for Extended Expansion Stroke
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Solution Overview
Problem
Conventional four-stroke reciprocating piston engines have limited efficiency due to the compression stroke being identical to the expansion stroke, resulting in higher pressure in the combustion chamber at the end of expansion, which prevents full recovery of energy from the expanding gaseous system.
Innovation Solution
An internal combustion engine with a planetary gear train and reciprocating pistons, featuring an extended expansion stroke compared to the compression stroke, utilizing an epicyclic gear train and a radial cam system to control valve opening, allowing for a more efficient conversion of thermal energy into mechanical energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional connecting rod crank system is used to transform reciprocating movements, then the engine structure is simple and reliable, but the expansion stroke cannot be extended beyond the compression stroke length, limiting energy recovery
Solution Approach 1:
The motion transformation system is segmented into two independent planetary gear sets: an active unit that transforms piston movements during compression and expansion strokes, and a passive unit that transforms piston movements during intake and exhaust strokes. This segmentation allows the expansion stroke to be extended independently from the compression stroke, enabling greater energy recovery while maintaining manageable system complexity through modular design
Solution Approach 2:
The two planetary gear sets are nested within the same engine structure, with the active and passive units sharing common components such as the crankshaft and cylinder arrangement. The passive unit is positioned to utilize the same spatial envelope as the active unit, allowing both motion transformation functions to coexist without significantly increasing the overall engine footprint or structural complexity
2Power
If the expansion stroke is extended to improve energy recovery, then more thermal energy can be converted to mechanical energy, but the engine architecture becomes more restrictive and complex
Solution Approach 1:
The planetary gear system is designed to automatically adjust the expansion stroke length based on the combustion pressure characteristics. During high-pressure combustion events, the gear ratios naturally facilitate extended expansion, while during low-pressure events, the system reverts to standard stroke lengths. This self-adjusting mechanism enables optimized power output without requiring complex external control systems or variable geometry mechanisms
Solution Approach 2:
The planetary gear sets serve multiple functions simultaneously: they transform reciprocating piston movements into rotational crankshaft movement, enable extended expansion strokes for improved energy recovery, and provide mechanical advantage multiplication. This multi-functionality allows the system to achieve enhanced power output without adding separate dedicated mechanisms for each function, thereby limiting the increase in overall architectural complexity
3Ease of manufacture
If the compression stroke is made identical to the expansion stroke as in conventional engines, then the mechanical transformation is straightforward, but the pressure in the combustion chamber remains high at the end of expansion, preventing full energy recovery
Solution Approach 1:
The planetary gear system creates an asymmetric relationship between the compression and expansion strokes by allowing the expansion stroke to be longer than the compression stroke. The active planetary unit achieves this through its specific gear ratio configuration, where the sun gear, planet gears, and ring gear are dimensioned to provide different effective stroke lengths for compression versus expansion phases, enabling full energy recovery while maintaining manufacturing feasibility through standard gear manufacturing processes
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
This design enhances energy recovery by maintaining higher pressure utilization, improving engine efficiency and power output without the need for additional components like turbochargers, while maintaining mechanical flexibility.
Implementation Method 1
an internal combustion engine with planetary gear train and reciprocating pistons... utilizing an epicyclic gear train... to transform the alternating translational movements of the pistons into continuous rotational movement
Implementation Method 2
a radial cam system to control valve opening... at least one radial cam guided in rotation around the axis Z arranged to be driven in rotation by at least one of the rotating members of the engine 1
Implementation Method 3
convert the thermal energy released by the combustion of a gaseous system in cylinders into mechanical energy... in which the four strokes of an engine cycle occur
Data Source
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AI summary
The invention relates to an internal combustion engine comprising cylinders which are arranged radially about an axis (Z), in each of which slides a piston performing reciprocating rectilinear movements which are reversibly transformed into a continuous rotation of an output shaft (105) by means of: an active unit and a passive unit (100,300), wherein each comprises a planet gear (102,302), the axis of which is parallel to (Z), which is capable of meshing with a sun gear (101,301) and which is maintained on its orbit by means of a planet carrier (103,303) and has a pitch diameter identical to the pitch radius of the corresponding sun gear. The planet gear (302) is rotatably driven by the planet gear (102) and/or the planet carrier (103). Each of the planet gears (102,302) is respectively secured to a connecting rod (104,304) having crank pins, the axes of which are parallel to the axis (Z), which pass through the pitch circle of the corresponding planet gear and are capable of cooperating by contact with rods secured to the pistons. The active unit (100) is intended, by means of the connecting rod (104), to ensure the compression and to transform the energy supplied to the pistons during the expansion into a rotary torque to the output shaft (105) while the passive unit (300) is intended, by means of the connecting rod (304), to ensure the exhaust and intake phases.