Variable Compression Ratio Engine via Phasing Device
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Solution Overview
Problem
Current internal combustion engines operating on the Atkinson cycle face challenges in varying compression ratios without increasing cost, weight, and packaging complexity, while maintaining fuel economy benefits.
Innovation Solution
An internal combustion engine design featuring a phasing device with an electric motor, gearbox, and gear system that adjusts the rotational speed of the control shaft relative to the crankshaft, allowing for selective variation of the compression stroke length and compression ratio, thereby enabling operation on the Atkinson cycle across different engine conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If technologies are added to vary compression ratio, then the ability to selectively vary compression ratio is improved, but cost and weight increase
Solution Approach 1:
The control shaft serves multiple functions: it controls the intake valve timing and duration, and simultaneously controls the compression ratio by adjusting the piston position at top dead center. This multi-functionality reduces the need for separate mechanisms, thereby reducing overall weight while maintaining compression ratio variability.
Solution Approach 2:
The patent combines the compression ratio control mechanism with the existing valve train system by using the control shaft to actuate both the intake valve and the piston position. This merging of functions into a single integrated system reduces the number of separate components, thereby reducing cost and weight.
2Adaptability or versatility
If technologies are added to vary compression ratio, then the ability to selectively vary compression ratio is improved, but packaging requirements increase
Solution Approach 1:
The control shaft performs multiple functions within a single component structure, controlling both valve timing and compression ratio. This eliminates the need for separate dedicated compression ratio control mechanisms, thereby reducing packaging requirements while maintaining the ability to vary compression ratio.
Solution Approach 2:
The patent integrates the compression ratio control function into the existing valve train architecture by having the control shaft simultaneously operate the intake valve and the piston position mechanism. This consolidation reduces the overall engine packaging volume while preserving compression ratio variability.
3Use of energy by moving object
If compression stroke length is reduced for Atkinson cycle, then fuel economy is improved, but compression ratio varies under different conditions
Solution Approach 1:
The patent employs a dynamic control system where the control shaft can adjust the piston position at top dead center based on operating conditions. This allows the compression ratio to be dynamically varied - maintaining a reduced compression stroke for fuel economy during efficient operating conditions, while increasing compression ratio when needed for high load or cold starting conditions.
Solution Approach 2:
The system changes the compression ratio parameter dynamically by adjusting the piston position at top dead center through the control shaft mechanism. This allows the engine to operate with a reduced compression stroke for fuel economy during normal conditions, while being able to increase compression ratio when performance requirements demand it.
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 allows for efficient fuel economy benefits by varying the compression ratio, maintaining the advantages of the Atkinson cycle across high load/high speed and low load/low speed conditions without adding significant cost or weight, and optimizing engine performance.
Implementation Method 1
A phasing device is supported by the engine block between and interconnecting the crankshaft and the control shaft and rotates the control shaft at a rotational speed relative to the rotational speed of the crankshaft
Implementation Method 2
An internal combustion engine design featuring a phasing device with an electric motor, gearbox, and gear system that adjusts the rotational speed of the control shaft relative to the crankshaft
Data Source
AI summary
A internal combustion engine comprises an engine block defining a cylinder bore, and a piston slideably supported within the cylinder bore. The piston slides reciprocally within the cylinder bore throughout an engine cycle through a piston compression stroke having a compression stroke length and a piston expansion stroke having an expansion stroke length. A crankshaft is rotatably supported by the engine block and rotatable about a crank axis, and a drive gear is co-axially mounted on the crankshaft. A control shaft is rotatably supported by the engine block and rotatable about a control axis that is parallel to and distal from the crank axis. A driven gear is coaxially mounted on the control shaft. A link rod is rotatably connected to the crankshaft and rotatable relative to the crankshaft about an axis that is parallel to and distal from the crank axis. A lower connecting rod has a first end rotatably connected to the link rod, and a second end rotatably connected to the control shaft and is rotatable relative to the control shaft about an axis that is parallel to and distal from the control axis, and an upper connecting rod has a first end rotatably connected to the link rod, and a second end rotatably connected to the piston. A phasing device is supported by the engine block between and interconnecting the crankshaft and the control shaft, and includes an idler shaft rotatable about a phase axis, an electric motor adapted to rotate the idler shaft, a gearbox mounted co-axially on the idler shaft, a crank gear supported on the gearbox co-axial to the idler shaft, and a control shaft gear mounted co-axially on the idler shaft distal from the crank gear. The drive gear engages the crank gear and transfers rotation of the crank shaft to the idler shaft, and the driven gear engages the control shaft gear and transfers rotation of the idler shaft to the control shaft, and when the electric motor rotates the idler shaft, the gearbox is adapted to allow the rotational speed of the idler shaft to change relative to the rotational speed of the crank shaft to change the rotational speed of the control shaft relative to the crankshaft and change the clearance volume.