Supercharger with heat insulated gear case

Abstract

A positive displacement supercharger includes a housing having a rotor cavity. A pair of positive displacement rotors are oppositely rotatable in the rotor cavity and have interleaved helical lobes forming rotor chambers operative to carry air axially from an inlet end to an outlet end of the cavity. A gear case adjacent the rotor cavity is drivably connected with and supports the rotors, the gear case including a bearing housing having an end surface facing the rotor cavity and the outlet ends of the rotors. A heat insulating material is applied to the end surface of the bearing housing and is effective to reduce heat flow between the rotor cavity and the end surface of the bearing housing to effectively reduce lubricating oil temperatures in the gear case. The insulating material may be a ceramic plate fixed to the bearing housing end surface.

1 . A positive displacement supercharger comprising:
 a housing including a rotor cavity having a surrounding cavity wall;   a pair of positive displacement rotors oppositely rotatable in the rotor cavity and having interleaved helical lobes forming rotor chambers operative to carry air axially from an inlet end of the cavity to an outlet end of the cavity;   a gear case received within the rotor cavity and drivably connected with and supporting the rotors at outlet ends thereof, the gear case including a bearing housing having an end surface facing the rotor cavity and the outlet ends of the rotors; and   a heat insulating material applied to the end surface of the bearing housing and effective to reduce heat flow between the rotor cavity, with the rotors and compressed air therein, and the end surface of the bearing housing to effectively limit lubricating oil temperatures in the gear case.   
   
   
       2 . A supercharger as in  claim 1  wherein the heat insulating material is a ceramic. 
   
   
       3 . A supercharger as in  claim 2  wherein the ceramic is formed as a preformed plate. 
   
   
       4 . A supercharger as in  claim 3  wherein the ceramic plate is secured to the end surface of the bearing housing by mechanical fasteners. 
   
   
       5 . A supercharger as in  claim 3  wherein the ceramic plate is secured to the end surface of the bearing housing by an adhesive.