Development of a Lightweight, Compact and Energy Efficient Pinch Valve Driven by Shape Memory Alloy Wires

In this paper, the development process of a shape memory alloy (SMA) driven pinch valve is proposed. The features of SMA actuator wires like small installation space, small weight, and the high energy density, allow for designing compact systems with high force outputs. A functional prototype is presented, allowing for closing forces of up to 250 N and 3 mm of stroke, which enables pinching hoses up to a diameter of 5 mm. It is driven by four mechanically parallel 500 micrometer diameter wires to open the valve and two 300 micrometer diameter to close the valve and cut off the medium flow inside of the hose. This SMA driven pinch valve features a spring-loaded toggle mechanism. It leads to stable and energy free position holding in both, opened and closed state of the valve, compared to commonly used valves, which allow for only one energy free position. As the system can be built without using any ferromagnetic materials the valve is predestined to be used in Magnetic Resonance Imaging (MRI). Due to the higher energy efficiency and weight reduction in comparison to commonly used solenoid pinch valves, they can be a substitute in a variety of applications.