Rocking Beam Stirling Drive for Piston Side-Load Reduction
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Solution Overview
Problem
Existing Stirling cycle machines face challenges due to increased side loads on pistons, leading to engine noise, reduced efficiency, and shorter lifespan, which existing improvements have attempted to address but often result in heavier and bulkier machines.
Innovation Solution
A rocking beam drive mechanism that converts linear piston motion to rotary motion, utilizing 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 and reduce angular deviation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional piston and crankshaft linkage is used, then rotary motion is achieved, but side loads on pistons increase causing noise, wear, and reduced efficiency
Solution Approach 1:
The coupling assembly is divided into multiple components: piston rod, link rod, and coupling means (flexible joint, roller bearing, hinge, or flexure). This segmentation allows each component to perform its specific function while collectively reducing side loads on the piston through the flexible coupling mechanism.
Solution Approach 2:
The coupling means acts as an intermediary between the piston rod and link rod, allowing relative motion and reducing the transmission of lateral forces. This intermediary element (flexible joint, roller bearing, hinge, or flexure) absorbs angular deviations and prevents direct transmission of side loads to the piston.
2Reliability
If drive mechanisms are improved to reduce side loads, then piston wear and noise decrease, but machine weight and bulk increase
Solution Approach 1:
Instead of trying to strengthen the piston and cylinder to withstand side loads, the invention inverts the approach by designing the coupling assembly to actively reduce side loads. The flexible joint, roller bearing, hinge, or flexure in the coupling means creates a mechanism that naturally minimizes lateral forces, achieving reliability without increased weight.
Solution Approach 2:
The invention changes the mechanical parameters of the coupling system by introducing flexible joints, roller bearings, hinges, or flexures that alter the force transmission characteristics. These parameter changes allow the system to operate with reduced side loads while maintaining compact dimensions and acceptable weight.
3Productivity
If piston alignment is not maintained, then lateral forces increase, but this causes increased friction and reduced machine efficiency
Solution Approach 1:
The coupling assembly introduces dynamic elements (flexible joint, roller bearing, hinge, or flexure) that allow the mechanism to adapt to angular deviations during operation. This dynamic coupling maintains optimal piston alignment by absorbing lateral movements, thereby reducing friction and improving overall machine efficiency.
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 effectively reduces side loads on pistons, enhancing the efficiency and lifespan of Stirling cycle machines while maintaining a compact design, thereby improving the operational performance and longevity of the engines.
Implementation Method 1
a rocking beam drive mechanism that converts linear piston motion to rotary motion, utilizing a rocking beam with a rocker pivot, coupling assemblies, and a crankshaft
Implementation Method 2
minimizing side loads through flexible joints and linear bearings to maintain linear piston motion
Implementation Method 3
minimizing side loads through flexible joints and linear bearings to maintain linear piston motion
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.