Fan/radiator combination for snowmobile with liquid cooled engine

Claim 1

In a snowmobile of the type including a frame, a body supported on said frame, said body including an engine compartment and a hood secured to said body in covering relation with respect to said engine compartment, an internal-combustion engine mounted in said engine compartment, said engine including an output shaft and liquid coolant passages extending through a cylinder block and cylinder head, the improvement comprising: (a) an air inlet opening formed through the thickness dimension of said body at a predetermined location relative to said engine compartment; (b) a radiator of the type including tube means held in spaced relation by a plurality of heat conducting fins for conveying a coolant liquid therethrough and disposed in said engine compartment in generally sealed relation with and proximate said air inlet opening in said body; (c) fan means operatively coupled to said output shaft for forcing air entering said opening over said heat conducting fins at a rate substantially proportional to the generated engine heat output; (d) sealed duct means disposed in said engine compartment and including a first portion surrounding said fan and said radiator for effectively excluding air in said engine compartment external of said duct means from the air stream being moved over said heat conducting fins by said fan, said first portion maintaining a negative pressure between said radiator and said fan for drawing air through said heat conducting fins; (e) said sealed duct means having a second portion downstream of said fan for exhausting heated air to the ambient; (f) coolant pump means operatively coupled to said output shaft to be driven by said shaft, said pump having a suction inlet and a pressure outlet; (g) hose means for coupling said inlet and outlet of said coolant pump means in fluid circuit with said tube means of said radiator and with said liquid coolant passages in said cylinder block and cylinder head, and (h) an exhaust connection attached to said engine within said engine compartment for carrying exhaust gases from one or more cylinders of said engine to an exhaust pipe, said exhaust connection having liquid coolant passages within the walls thereof, said liquid coolant passages of said exhaust connection being in said fluid circuit and isolated from said exhaust gases.