Hybrid coolant pump

Abstract

A hybrid coolant pump with two modes of operation, an electric motor operation and a mechanical pulley-driven operation. A friction clutch assembly is positioned inside the motor housing and includes a softening spring which minimizes parasitic clutch power consumption.

What is claimed is: 
     
         1 . A method of operating a dual mode coolant pump for a vehicle, said coolant pump comprising an impeller shaft with an impeller at one end, an electronic motor drive for rotating said impeller shaft, a mechanical drive for rotating said impeller shaft, a clutch mechanism for engaging and disengaging said mechanical drive from said impeller shaft, and a control system for activating said clutch mechanism, for engaging and disengaging said mechanical drive and for activating and deactivating said electric motor drive; said method of operating said coolant pump comprising:
 activating said electric motor drive and disengaging said mechanical drive during a first range of operation of said coolant pump;   engaging said mechanical drive during a second range of operation of said coolant pump;   activating said electric motor drive and disengaging said mechanical drive during a third range of operation of said coolant pump, said third range of operating being an over-drive condition; and   wherein said second range of operation is greater than said first range of operation.   
     
     
         2 . The method as described in  claim 1  wherein said electric motor is a brushless DC motor. 
     
     
         3 . The method as described in  claim 1  wherein said mechanical drive comprises an engine pulley. 
     
     
         4 . The method as described in  claim 1  wherein said clutch mechanism is a friction clutch mechanism. 
     
     
         5 . The method as described in  claim 4  wherein said friction clutch mechanism comprises a carrier member, a flux plate member, a solenoid member, a friction lining carrier member, and a spring member. 
     
     
         6 . The method as described in  claim 5  wherein said spring member is a compression spring member. 
     
     
         7 . The method as described in  claim 1  wherein said second range of operation comprises efficiency loss in the electric drive mode. 
     
     
         8 . The method as described in  claim 1  wherein said second range of operation comprises pump impeller speeds from 0 to about 7000 rpm, and said first range of operation comprising pump impeller speeds from 0 to about 4000 rpm. 
     
     
         9 . A method of comprising a dual mode coolant pump for a vehicle, said coolant pump comprising an impeller shaft with an impeller at one end, an electric motor drive for rotating said impeller shaft, a mechanical drive for rotating said impeller shaft, a clutch mechanism for engaging and disengaging said mechanical drive from said impeller shaft, and a control system for activating said clutch mechanism, for engaging and disengaging said mechanical drive for an activating and deactivating said electric motor drive; said method of operating said coolant pump comprising:
 activating said electric motor drive and disengaging said mechanical drive during a first range of operation of said coolant pump; and   wherein said second range of operating is greater than said first range of operation.   
     
     
         10 . The method as described in  claim 9  wherein said electric motor is a brushless DC motor. 
     
     
         11 . The method as described in  claim 9  wherein said mechanical drive comprises an engine pulley. 
     
     
         12 . The method as described in  claim 9  wherein said clutch mechanism is a friction clutch mechanism. 
     
     
         13 . The method as described in  claim 9  wherein said friction clutch mechanism comprises a carrier member, a flux plate member, a solenoid member, a friction lining carrier member, and a spring member. 
     
     
         14 . The method as described in  claim 9  wherein said spring member is a compression spring member. 
     
     
         15 . The method as described in  claim 9  wherein said second range of operation comprises efficiency loss in the electric drive mode. 
     
     
         16 . The method as described in  claim 9  wherein said second range of operation comprises pump impeller speeds from 0 to about 7000 rpm, and said first range of operation comprising pump impeller speeds from 0 to about 4000 rpm.