Supercharger charge air cooler with improved air flow characteristics

A supercharger for supplying pressurized air to an engine including:

• a housing,
• meshing rotors with their outer surfaces in sealing contact with the housing, the housing having an inlet port to admit air between the meshing rotors and an outlet port to expel pressurized air from the meshing rotors, the rotors accepting air from the inlet port and propelling it in a heated and pressurized state to the outlet port as the rotors are rotated, and
• a charge air cooler adjacent the outlet port to receive and remove heat from the flow of pressurized air propelled through the outlet port by the rotors in order to reduce the temperature and increase the density of the pressurized air supplied to the engine,
• wherein the charge air cooler comprises:
• an inlet-side core for transmitting the flow of air propelled by the rotors, and
• an outlet-side core spaced from the inlet-side core to form an air chamber therebetween and receiving the flow of heated and pressurized air transmitted from the inlet-side core and further transmitting the flow of air,
• each core having
• coolant conduits extending transversely to the flow of air, the coolant conduits conducting a flow of liquid coolant through the coolant conduits in the outlet-side core and the inlet-side core, and
• fins joined to the coolant conduits for contact with the flow of air, the fins being arranged with a predetermined density, and
• the inlet-side core fin density being lower than the outlet-side core fin density, whereby the inlet-side core presents less resistance to the flow of air than the outlet-side core and the outlet-side core presents greater surface area for heat conductance from the flow of air than the inlet-side core,
• the different fin densities providing a first pressure drop in the inlet-side core and a second pressure drop in the outlet-side core and a first temperature drop in the inlet-side core and a second temperature drop in the outlet-side core such that the combined pressure and temperature drops in the two cores produce a lower pressure drop and higher temperature drop than in inlet-side and outlet-side cores with identical fin density, for more efficient operation of the charge air cooler.

A method of operating a supercharger to supply pressurized air to an engine, comprising;

• providing a housing with rotors sealingly mounted for rotation therein;
• accepting air into the housing from an inlet port and propelling it in a heated and pressurized state from the housing through an outlet port as the rotors are rotated,
• passing the air propelled from the housing outlet port through a charge air cooler having an upstream core and a downstream core spaced from the upstream core to form an air chamber therebetween, each core having coolant conduits for conducting a flow of liquid coolant transversely to the flow of air and fins joined to the coolant conduits for contact with the flow of air,
• arranging the fins in each core with a predetermined density, the upstream core fin density being lower than the downstream core fin density,
• first transmitting the flow of air propelled by the rotors through the upstream core with lower fin density, through the air chamber and to the outlet-side core, and
• then transmitting the air received from the upstream core through the downstream core with greater fin density and to the engine,
• whereby the upstream core presents less resistance to the flow of air than the downstream core and the downstream core presents greater surface area for heat conductance from the flow of air than the upstream core,
• the different fin densities providing a first pressure drop in the upstream core and a second pressure drop in the downstream core and a first temperature drop in the upstream core and a second temperature drop in the downstream core such that the combined pressure and temperature drops in the two cores produce a lower pressure drop and higher temperature drop than in upstream and downstream cores with identical fin density, for more efficient operation of the charge air cooler.