Stirling Cycle Drive Mechanism With Rocking Beam Piston Alignment
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Solution Overview
Problem
Stirling cycle machines face challenges due to friction and side loads from misaligned pistons, leading to increased noise, reduced efficiency, and shorter engine life, with existing improvements resulting in heavier and bulkier machines.
Innovation Solution
A rocking beam drive mechanism that converts linear piston motion to rotary motion, using a rocking beam with a rocker pivot, coupling assemblies, and a crankshaft, minimizing side loads through flexible joints and linear bearings to maintain linear piston motion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If traditional piston and crankshaft linkage is used, then rotary motion is achieved, but side loads and friction increase leading to reduced efficiency and increased noise
Solution Approach 1:
A rocking beam is introduced as an intermediary component between the piston and crankshaft. The piston connects to the rocking beam via a coupling assembly, which then connects to the crankshaft. This intermediary rocking beam converts the piston's linear motion into rotary motion while maintaining minimal side loads on the piston throughout the entire motion cycle, resolving the contradiction between energy efficiency and operational smoothness.
Solution Approach 2:
The coupling assembly incorporates dynamic elements including a flexible joint and roller bearing that allow the connection between piston and rocking beam to adapt during motion. The roller bearing rides in a slot on the rocking beam, creating a dynamic constraint system that maintains proper alignment and minimizes friction while allowing the necessary motion transformation.
2Loss of energy
If drive mechanisms are improved to reduce side loads, then efficiency increases, but the machine becomes heavier and bulkier
Solution Approach 1:
The drive mechanism is segmented into distinct functional components: the piston, coupling assembly with roller bearing, rocking beam, and crankshaft. This segmentation allows each component to be optimized for its specific function while keeping the overall design compact. The rocking beam acts as a separate lever arm that transforms motion without adding significant weight, unlike traditional连杆 mechanisms that require heavier components to manage side loads.
Solution Approach 2:
Multiple functions are merged into the rocking beam component. It serves as both the motion transformation element and the structural link between piston and crankshaft. The coupling assembly combines the flexible joint and roller bearing into a single integrated connection system, reducing the number of separate components and overall machine weight while maintaining efficiency.
3Productivity
If piston alignment is maintained to reduce friction, then efficiency improves, but complexity of drive mechanism increases
Solution Approach 1:
The rocking beam serves as a mediator that simplifies the overall mechanism by providing a straightforward lever arm connection. Instead of complex multi-linkage systems or guided mechanisms to maintain piston alignment, the rocking beam's pivot geometry naturally constrains the piston to linear motion while maintaining minimal side loads throughout the cycle, achieving alignment without excessive complexity.
Solution Approach 2:
The coupling assembly uses a roller bearing that moves in a curved slot on the rocking beam. This curved path provides the necessary geometric constraint to maintain proper alignment between piston and rocking beam throughout the motion cycle, ensuring efficient operation with minimal friction while using a simple curved geometry rather than complex mechanical constraints.
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
The solution reduces side loads on pistons, enhancing the efficiency and lifespan of Stirling cycle machines while maintaining a compact design, improving noise reduction and operational stability.
Implementation Method 1
a rocking beam having a rocker pivot, at least one cylinder and at least one piston. The piston is housed within a respective cylinder. The piston is capable of substantially linearly reciprocating within the respective cylinder
Implementation Method 2
The linear motion of the piston is converted to rotary motion of the rocking beam
Implementation Method 3
minimizing side loads through flexible joints and linear bearings to maintain linear piston motion
Implementation Method 4
The linear bearing includes an opening to accommodate the coupling assembly
Implementation Method 5
minimizing side loads through flexible joints and linear bearings to maintain linear piston motion
Implementation Method 6
at least one coupling assembly having a proximal end and a distal end. The proximal end is connected to the piston and the distal end is connected to the rocking beam by an end pivot
Data Source
AI summary
A Stirling cycle machine with a liquid fuel/gaseous fuel burner. The burner may include a preheater to capture the thermal energy of the exhaust. The burner directs the preheated air to each burner head, where it enters a prechamber. Each burner head includes a fuel nozzle that directs liquid or gaseous fuel into the prechamber. The prechamber is fluidically connected to a combustion chamber via a prechamber nozzle that has a smaller opening than the prechamber. The burner head ignites the fuel air mixture in the prechamber with an ignitor located above or within the prechamber. The flame is initially lit as a diffusion flame in the prechamber. The flame is pushed out of the prechamber into the combustion chamber by an increased air flow rate. The liquid fuel from the nozzle now evaporates in the prechamber and forms a prevaporized flame in the combustion chamber.