Rotating Piston Assembly for Variable Compression Ratio
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Solution Overview
Problem
Dual fuel engines with fixed compression ratios operate suboptimally for both natural gas and diesel fuels, as natural gas engines typically have lower compression ratios than diesel engines, limiting their efficiency.
Innovation Solution
A piston assembly that rotates to change compression ratios by using a hydraulic chamber with active and passive fluid pressures, allowing the engine to switch between low and high compression ratios, enabling efficient operation with both natural gas and diesel fuels by adjusting the distance between the piston and pin carrier.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed compression ratio is used in dual fuel engines, then the engine structure remains simple, but the engine operates suboptimally for both natural gas and diesel fuels
Solution Approach 1:
The piston assembly is designed to rotate between two orientations (low compression ratio orientation and high compression ratio orientation) to dynamically adjust the compression ratio based on the fuel being used. This dynamic adjustment allows the engine to optimize performance for either natural gas or diesel fuel while maintaining a relatively simple mechanical structure through the use of hydraulic pressure to drive the rotation.
2Adaptability or versatility
If hydraulic fluid is supplied at active fluid pressure to rotate the piston, then the compression ratio increases to high compression ratio, but the hydraulic system complexity increases
Solution Approach 1:
The hydraulic system is designed to use the engine's own lubricating oil as the hydraulic fluid, eliminating the need for a separate hydraulic fluid reservoir and pump system. The lubricating oil is diverted through control valves to create hydraulic pressure for piston rotation, and the system uses the engine's existing mechanical resources to maintain and circulate the hydraulic fluid, thereby reducing overall system 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
Enables efficient operation of dual fuel engines by adjusting compression ratios from less than 15:1 to greater than 15:1, improving fuel efficiency and adaptability between natural gas and diesel modes.
Implementation Method 1
The piston rotates from a low compression ratio orientation with respect to the piston carrier to a high compression ratio orientation responsive to an active fluid pressure in the hydraulic chamber
Implementation Method 2
The piston rotates from the high compression ratio orientation to the low compression ratio orientation responsive to a passive fluid pressure, which is less than the active fluid pressure, in the hydraulic chamber
Implementation Method 3
The piston has a plurality of first wedges respectively contacting a plurality of second wedges of the pin carrier in a hydraulic chamber. Each of the first wedges has a hydraulic surface exposed to fluid pressure in the hydraulic chamber
Data Source
AI summary
An internal combustion engine includes a piston assembly with a piston rotatably connected to a pin carrier. The piston can rotate about a cylinder axis from a low compression ratio orientation to a high compression ratio orientation when an electronically controlled pump of a compression ratio controlled fluid circuit is activated. The piston includes a plurality of first wedges in contact with a plurality of respective second wedges of the pin carrier in a hydraulic chamber. The first wedges have hydraulic surfaces exposed to fluid pressure in the hydraulic chamber in order to hydraulically rotate the piston relative to the pin carrier. The engine may be configured to burn diesel fuel and natural gas.