Piston Engine Fluid Bearing Clearance Control
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Solution Overview
Problem
Piston engines face challenges in managing the clearance gap between the piston and cylinder, leading to increased heat transfer, friction, and mechanical losses due to higher compression ratios, which affect combustion phasing and component durability.
Innovation Solution
The implementation of a piston engine system that includes a fluid bearing in the clearance gap, self-centering features, heat pipes, and adjustable cylinder liners to control the clearance gap and temperature, utilizing fluid passages and sensors to manage the gap and prevent piston-cylinder contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If compression ratio is increased, then thermal efficiency is improved, but heat transfer from combustion chamber increases
Solution Approach 1:
A fluid bearing is introduced as an intermediary substance between the piston and cylinder wall to manage heat transfer. The bearing fluid acts as a thermal mediator that controls the rate of heat transfer from the combustion chamber through the piston, allowing high compression ratios to be maintained while preventing excessive heat transfer that would otherwise occur through direct contact.
2Power
If compression ratio is increased, then power output is improved, but friction and mechanical losses increase
Solution Approach 1:
A fluid bearing system is implemented between the piston and cylinder wall, replacing traditional mechanical contact with fluid film support. This pneumatic/hydraulic approach eliminates solid-to-solid friction, allowing the engine to operate at high compression ratios that increase power output without the corresponding increase in friction losses that would normally accompany higher mechanical loads.
3Productivity
If compression ratio is increased, then combustion efficiency is improved, but combustion phasing control becomes difficult
Solution Approach 1:
The fluid bearing serves as a thermal intermediary that modulates heat transfer rates, which in turn affects combustion chamber temperature and pressure profiles. This intermediary control mechanism allows for better management of combustion phasing by adjusting thermal conditions, enabling high compression ratios to achieve improved combustion efficiency while maintaining controllable combustion timing.
4Loss of energy
If clearance gap is reduced, then mechanical losses are reduced, but piston alignment and prevention of piston-wall contact becomes difficult
Solution Approach 1:
A fluid bearing system is introduced to replace direct mechanical contact between the piston and cylinder wall. The fluid film maintains a controlled clearance gap that prevents piston-wall contact and ensures proper piston alignment through hydrodynamic or hydrostatic pressure distribution, while the narrow gap minimizes mechanical losses from leakage and friction.
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 solution reduces friction and mechanical losses, improves combustion efficiency, and enhances the durability of engine components by maintaining optimal clearance and temperature control.
Implementation Method 1
The heat pipe may include a fluid such as, for example, water, ethanol, ammonia, or sodium, which may undergo a vapor-liquid phase transition.
Implementation Method 2
a fluid bearing in the clearance gap between a bore of a cylinder and a piston assembly
Data Source
AI summary
A piston engine may include a piston and cylinder assembly. A piston assembly may be configured to translate in a cylinder liner, which may form a bore in the cylinder. The cylinder liner may be deformable, and deformations of the cylinder liner may affect the clearance gap between the piston assembly and the cylinder. A liner fluid may be supplied to the cylinder liner to create a pressure differential across the liner, and a resulting deformation. The liner fluid may be used to provide cooling as well as liner deformation to control the clearance gap. A cylinder may include one or more fluid passages configured to provide heating, cooling, or both. A cylinder may include one or more localized heat sources such as, for example, electric resistance heaters or heating fluid passages.