Protecting car engines and controlling their temperature by using shape memory alloy as an automatic mechanical cooling sensor

Abstract

Shape memory alloys (SMA) are smart materials with a dual function as a sensor as well as an actuator that can generate cyclic contraction and extension when exposed to an increasing and decreasing temperature. In this work, the potential of SMA in the form of spring as an actuator that activates a warning system for detecting high temperatures in vehicle engine is investigated. The working principle of SMA spring is it activates thermomechanically to generate linear reciprocating motion as a result of the contraction (heated) and extension (cooled). This unique feature is employed in the design of a new type of smart automatic switch that regulates and controls the temperature of the vehicle engine instead of using conventional sensors such as thermocouple. The smart automatic switch has two poles positive and negative, where the positive pole represents the SMA spring, which is completely immersed in the water of the engine. While the negative pole is the operating shaft that collects all the parts of the smart switch and is installed on the engine body. A lab scale experiment was conducted to analyse the displacements and results shown that contraction of 20 mm can be produced from the SMA spring due to pulling force when the temperature of the engine increases from 50 ℃ to 80 ℃ and the recovery of the SMA spring to the original position can be obtained by the pushing force 0.5 N from a bias spring when the temperature decreased. From this experiment, a design of the smart switch is that can be utilized the shape memory function is presented. The simplified design proposed demonstrates the shape memory alloy as having good potential in automotive applications such as this as it low cost, space saving, silent operation, and simple in design aspect.