Shape Memory Alloy Drive With Dual Reservoir Thermal Cycling
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Solution Overview
Problem
Existing drive systems that convert thermal energy into mechanical or electrical energy using shape memory alloys face challenges in maintaining consistent temperature differences and are often complex and expensive due to the need for specialized mechanisms to move the shape memory elements.
Innovation Solution
A drive system utilizing a metal element with shape memory characteristics, such as Nitinol, that contracts uniaxially within a cylinder housing, with separate temperature-controlled media reservoirs and valves to maintain temperature differences, allowing for efficient energy conversion through a cyclic pumping process controlled by a reciprocating cylinder piston.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a specialized mechanism is used to move the shape memory element, then the shape memory element can be actuated, but the device complexity and cost increase
Solution Approach 1:
The shape memory element actuates itself through direct thermal exposure without requiring external mechanical actuation mechanisms. The metal element undergoes thermal expansion and contraction in response to temperature changes, eliminating the need for complex specialized mechanisms to move it.
Solution Approach 2:
The patent replaces mechanical actuation mechanisms with direct thermal action. Instead of using mechanical devices to move the shape memory element, the system uses thermal energy directly to induce expansion and contraction of the metal element, substituting a mechanical system with a thermal field approach.
2Productivity
If temperature differences are not maintained, then the system is simpler, but energy conversion efficiency decreases
Solution Approach 1:
The system utilizes the phase transition properties of the shape memory alloy, which undergoes reversible martensitic transformation at specific temperatures. By maintaining temperature differences, the metal element cycles between austenite and martensite phases, enabling continuous energy conversion without requiring complex active temperature control mechanisms.
Solution Approach 2:
The patent changes the temperature parameter to control the state of the shape memory element. By varying temperature between hot and cold reservoirs, the system controls the expansion and contraction of the metal element, achieving efficient energy conversion through simple thermal parameter changes rather than complex control mechanisms.
3Use of energy by moving object
If the metal element is exposed to excessive temperature, then thermal energy can be utilized, but the metal element loses its cycling properties and becomes damaged
Solution Approach 1:
The system incorporates feedback through the cyclic operation of the shape memory element. The metal element's phase transformation properties provide inherent feedback - when the temperature exceeds the maximum threshold, the element undergoes irreversible changes that prevent further cycling. This feedback mechanism naturally limits temperature exposure to protect the element's reliability.
Solution Approach 2:
The patent designs the system with pre-established temperature boundaries and protective measures. The housing structure and thermal management system are configured beforehand to prevent excessive temperature exposure, cushioning against potential damage before it occurs by maintaining temperatures within the safe operating range of the shape memory alloy.
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 system effectively converts thermal energy into mechanical work with high efficiency and simplicity, maintaining consistent temperature differences and reducing the complexity and cost of the drive system, enabling the use of waste heat as an energy source.
Implementation Method 1
at least one metal element (20) having shape memory characteristics, in particular in the form of a nitinol spring
Implementation Method 2
The contraction of the metal element preferably takes place in a uniaxial direction and is reversible
Implementation Method 3
maintaining consistent temperature differences and reducing the complexity and cost of the drive system, enabling the use of waste heat as an energy source
Data Source
Figure 1
Figure 2
Figure 3(a)~3(d)
AI summary
The invention relates to a drive system (100; 200; 300) based on the cyclical conversion of thermal energy into mechanical or electrical energy using a temperature difference between at least two media (M1, M2) and the contraction of a metal element exhibiting shape memory properties. According to the invention, the drive system (100; 200; 300) comprises a first and a second store (11; 12) containing media (M1, M2) at different temperatures (T1, T2), the second store (12) having a passage (36) for direct connection through the bottom (18) of the housing (34). The housing (34) is a cylinder (10) containing a cylinder piston (15) arranged in a liquid-tight and gas-tight manner and dividing the cylinder (10) into two cylinder spaces (14; 16) of variable volumes, one cylinder space (14) containing the metal element (20) and the other cylinder space (16) containing the restoring element (37). The metal element (20) is secured to a fixing point (A) on the cylinder piston (15) and to a fixing point (B) located inside the second store (12) such that part (33) of the metal element (20) is in contact with the medium of the second store (12).