Coolant pump with electric motor drive and mechanical drive

Abstract

The invention relates to a coolant pump ( 15 ) having a pump wheel ( 13 ) which is arranged on a pump wheel shaft ( 3, 11 ); and having a drive device ( 1; 8, 9 ) for the pump wheel ( 13 ), which drive device has a mechanical drive ( 1 ) and which drive device has an electric-motor drive ( 8, 9 ), wherein the pump wheel shaft is divided into a driving section ( 3 ) and a driven section ( 11 ), and an openable and closable clutch ( 4 ) is arranged between the driving section ( 3 ) and the driven section ( 11 ).

What is claimed is: 
     
         1 . A method for operating a dual mode coolant pump for a vehicle engine, said coolant pump comprising an impeller shaft having a driving section and a driven section, an impeller member at one end of said shaft for circulating coolant in said engine, an electric motor drive for rotating said impeller shaft at said driven section, a mechanical drive for rotating said impeller shaft at said driving section, a clutch mechanism for engaging and disengaging said mechanical drive from said impeller shaft, and a control system for activating and deactivating said mechanical drive and said electric motor drive, said method of operating said coolant pump comprising:
 activating said electric motor drive and deactivating said mechanical drive for pumping coolant through said engine during a first range of impeller rotation speed;   activating said mechanical drive and deactiving said electric motor drive for pumping coolant through said engine during a second range of impeller rotation speed;   said second range of impeller rotation speed being greater than said first range of impeller rotation speed.   
     
     
         2 . The method as set forth in  claim 1  wherein said first range of impeller rotation speed is from about 1000 rpm to about 1500 rpm. 
     
     
         3 . The method as set forth in  claim 1  wherein said second range of impeller rotation is from about 1000 rpm to about 2500 rpm. 
     
     
         4 . The method as set forth in  claim 1  wherein said electric motor is a brushless DC motor. 
     
     
         5 . The method as set forth in  claim 1  wherein said mechanical drive comprises a pulley. 
     
     
         6 . The method as set forth in  claim 1  wherein said clutch mechanism is an openable and closeable clutch. 
     
     
         7 . The method as set forth in  claim 1  wherein said mechanical drive is engaged on the basis of pressure measurements. 
     
     
         8 . The method as set forth in  claim 1  wherein said mechanical drive is engaged on the basis of monitoring of supply of electrical energy. 
     
     
         9 . The method as set forth in  claim 1  wherein said first range of impeller rotation speed comprises coolant temperature from about 80° C. to about 94° C. 
     
     
         10 . The method as set forth in  claim 1  wherein said second range of impeller rotation speed comprises coolant temperature from about 90° C. to about 96° C. 
     
     
         11 . The method as set forth in  claim 1  wherein an auxiliary coolant pump is not required for the vehicle engine. 
     
     
         12 . The method as set forth in  claim 1  further comprising the step of recovering electrical energy from the electric motor drive when said mechanical drive is exclusively activated.