Opposed-Piston Piston Assembly for Cooling and Injector Placement
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Solution Overview
Problem
Existing opposed-piston engine piston designs face challenges in achieving effective piston thermal management and compact engine configurations due to restrictions on the placement of stationary oil jets and fuel injectors caused by the separate wristpin support structure.
Innovation Solution
The piston design eliminates the separate wristpin support structure, allowing for a wristpin bore formed integrally with the piston skirt, which enables more favorable positioning of stationary oil jets and fuel injectors, particularly with diametrically-opposed injection regions on the end surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate wristpin support structure is used, then the wristpin can be properly supported, but the placement of stationary oil jets and fuel injectors is restricted
Solution Approach 1:
The patent merges the separate wristpin support structure with the piston skirt by forming the wristpin bore integrally with the piston skirt. This integration eliminates the need for a separate support structure and its attachment features, thereby removing the restrictions on placing stationary oil jets and fuel injectors. The wristpin is now directly supported by the integral bore in the piston skirt, enabling more flexible and favorable positioning of cooling and injection components.
2Volume of moving object
If stationary oil jets are positioned favorably for compact engine configuration, then engine size is reduced, but piston thermal management effectiveness is compromised
Solution Approach 1:
By integrating the wristpin bore directly into the piston skirt, the patent removes the attachment features that previously constrained oil jet positioning. This allows stationary oil jets to be optimally positioned for both compact engine configuration and effective piston thermal management, resolving the trade-off between engine size and cooling effectiveness.
Solution Approach 2:
The patent enables different regions of the piston to have optimized local characteristics. The integral wristpin bore allows stationary oil jets to be positioned at specific locations that provide favorable cooling to the piston crown and end surface, while maintaining compact overall engine dimensions. This local optimization of cooling delivery addresses the thermal management requirement without compromising compactness.
3Ease of manufacture
If injection regions are positioned on the end surface, then fuel injection is enabled, but the separate wristpin support structure restricts optimal positioning
Solution Approach 1:
The integration of the wristpin bore into the piston skirt eliminates the attachment features that restricted injection region positioning. This allows injection regions to be optimally positioned on the end surface for effective fuel injection, while the integral structure provides the necessary support without geometric constraints from separate mounting features.
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 piston thermal management by allowing for more effective coolant delivery and fuel injection, while also enabling a more compact engine configuration by optimizing the placement of oil jets and fuel injectors.
Implementation Method 1
streams of liquid coolant enter the annular cooling gallery
Implementation Method 2
optimal cooling effect when the streams of coolant are aligned with injection trenches
Implementation Method 3
stationary oil jets that deliver the streams of coolant to the annular cooling gallery
Implementation Method 4
fuel emitted through diametrically-opposed fuel injectors enters a combustion chamber
Implementation Method 5
fuel injected into the charge air... The mixture of charge air and fuel is compressed... When compression causes the mixture to reach an ignition temperature, the fuel ignites. Combustion results, driving the pistons apart
Data Source
AI summary
A piston for an opposed-piston, internal combustion engine includes a crown with an end surface having a bowl shaped to form a combustion chamber with an end surface of an opposing piston in the opposed-piston engine. A substantially circumferential top land of the crown meets the end surface at a substantially circular peripheral edge, and a skirt comprising a sidewall extends from a substantially circumferential belt region of the crown. A wristpin bore with a wristpin axis opens through the sidewall. The end surface of the piston includes a pair of injection regions across which fuel is injected into the bowl. The injection regions are disposed in substantially diametrically-opposed quadrants of the end surface which are defined by the wristpin axis and a connecting rod envelope axis substantially orthogonal to the wristpin axis. Each injection region extends along a respective arc concentric with the substantially circular peripheral edge.