Non-return valve and filter arrangement

A non-return valve for protecting an air filter from backflow of hot exhaust gases, said non-return valve comprising:

• a valve body having a flow passage extending between inlet and outlet ends of said valve body;
• a valve plate arranged in and slideably constrained to move along a predetermined axis in said valve body, said valve plate movable between an open position and a closed position;
• a force generating elastic element acting upon said valve plate urging said valve plate to move in a blocking direction into said closed position along said axis;
• an elongated guide pin arranged mounted within said valve body and defining said axis along which said valve plate moves, said guide pin extending in said valve body at least partially between inlet and outlet ends of said valve body;
• a sleeve received over and surrounding an exterior of said guide pin, said sleeve having an axial bore into which at least a portion of said guide pin is slideably received, said sleeve including
• a first sleeve section slideably received over and guided by sliding contact with and along a guide surface of said guide pin;
• a second sleeve section circumferentially surrounding at least a portion of a length of said guide pin;
• wherein said sleeve is slidably moveable along at least a portion of a length of said guide surface of said guide pin,
• wherein at least a portion of said elastic element is arranged within said second sleeve section between said second sleeve section and said guide pin,
• wherein said valve plate is mounted to said sleeve to slideably move with said sleeve along said guide pin within said valve body,
• wherein said non-return valve prevents a fluid flow through said valve body in a blocking direction and otherwise releases the fluid flow through said flow passage of said valve body in a direction opposite said blocking direction.