Shape memory alloy actuator for valve for a vapour compression system

An actuator for a valve in a refrigeration system, the actuator comprising:

• an elongated Shape Memory Alloy element having a distal end configured to be distant to a valve element of the valve and a proximal end configured to be proximate to the valve element of the valve, the Shape Memory Alloy element extending from the distal end to the proximal end, the distal end of the Shape Memory Alloy element being connected to a housing of the Shape Memory Alloy element, the Shape Memory Alloy element being electrically insulated from the housing;
• an encapsulation that encapsulates at least a portion of the Shape Memory Alloy element;
• and
• an elastic element disposed between the encapsulation and the valve element;
• wherein the Shape Memory Alloy element comprises at least two extensions, and wherein the encapsulation comprises at least two pipes or two tubes or two rods, each of the at least two pipes or two tubes or two rods having an elongated internal cavity for accommodating one of the at least two extensions of the Shape Memory Alloy;
• and
• wherein a thermal conductivity of the encapsulation is lower than a thermal conductivity of the Shape Memory Alloy element.

A valve for a vapour compression system, comprising:

• a valve body with at least one inlet and at least one outlet;
• a valve element positioned inside the valve body;
• a stop positioned inside the valve body having a proximal side facing the valve element and a distal side facing away from the valve element;
• and
• an actuator comprising:
• a Shape Memory Alloy element having a distal end distant to the valve element and a proximal end proximate to the valve element, the Shape Memory Alloy element comprising at least a first extension and a second extension extending from the distal end to the proximal end;
• a first encapsulation encapsulating the first extension of the Shape Memory Alloy element, the first encapsulation providing a thermal resistance between a temperature of the first extension of the Shape Memory Alloy element and a temperature of an environment of the first encapsulation;
• and
• a second encapsulation encapsulating the second extension of the Shape Memory Alloy element, the second encapsulation providing a thermal resistance between a temperature of the second extension of the Shape Memory Alloy element and a temperature of an environment of the second encapsulation;
• wherein the first and second encapsulations extend through the stop so that at least a first portion of the first encapsulation and a first portion of the second encapsulation extend beyond the distal side of the stop, and at least a second portion of the first encapsulation and a second portion of the second encapsulation extend beyond the proximal side of the stop;
• wherein a thermal conductivity of the first encapsulation is lower than a thermal conductivity of the Shape Memory Alloy element;
• and
• wherein a thermal conductivity of the second encapsulation is lower than the thermal conductivity of the Shape Memory Alloy element.