Stirling Cycle Machine Rocking Beam Drive Mechanism
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Solution Overview
Problem
Existing Stirling cycle machines face challenges with friction and side loads due to piston misalignment and lateral forces, leading to increased noise, wear, and reduced efficiency and lifespan, with previous 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
1Ease of operation
If traditional piston and crankshaft linkage is used, then rotary motion is achieved, but side loads and friction increase due to piston misalignment
Solution Approach 1:
A coupling assembly with coupling means is introduced as an intermediary between the piston rod and rocking beam. This coupling means accommodates misalignment and reduces lateral forces on the piston, allowing the piston to maintain linear motion while still transmitting force to the rocking beam for rotary motion conversion.
Solution Approach 2:
The system changes the operational parameters by allowing controlled angular deviation of the coupling assembly and rocking beam during operation. This dynamic parameter adjustment enables the mechanism to adapt to operational conditions, maintaining linear piston motion while achieving rotary output without excessive side loads.
2Reliability
If drive mechanisms are improved to reduce side loads, then piston friction decreases, but the machine becomes heavier and bulkier
Solution Approach 1:
The coupling assembly incorporates flexible coupling means that dynamically adapt to misalignment conditions during operation. This dynamic capability allows the system to reduce side loads on the piston without requiring heavy rigid alignment mechanisms, maintaining lightweight construction while improving reliability.
Solution Approach 2:
The drive mechanism is segmented into distinct functional components: the piston rod, coupling assembly with coupling means, rocking beam, and crankshaft. This segmentation allows each component to be optimized independently, enabling the coupling means to handle misalignment without requiring the entire mechanism to be oversized or heavier.
3Ease of operation
If coupling assembly allows angular deviation, then linear piston motion is maintained, but mechanical efficiency may be reduced
Solution Approach 1:
The coupling means is designed to accommodate small angular deviations and misalignments through controlled parameter changes in the coupling geometry. By allowing these minor parameter variations, the system maintains linear piston motion while minimizing energy loss through friction and misalignment, preserving mechanical efficiency.
Data Source
AI summary
A Stirling cycle machine. The machine includes at least one rocking drive mechanism including a rocking beam having a rocker pivot, at least one cylinder and at least one piston. The piston is housed within a respective cylinder and is capable of substantially linearly reciprocating within the respective cylinder. The drive mechanism includes at least one coupling assembly. Also, a crankcase housing the rocking beam and housing a first portion of the coupling assembly is included. The machine also includes a working space housing the at least one cylinder, the at least one piston and a second portion of the coupling assembly. An airlock is included between the workspace and the crankcase and a seal is included for sealing the workspace from the airlock and crankcase. A burner and burner control system is also included for heating the machine and controlling ignition and combustion in the burner.