Mechanical switchable automotive coolant pump

Abstract

A coolant pump for providing a coolant to an engine includes a pump frame, a rotatable rotor shaft, a pulley wheel co-rotatably fixed to the rotor shaft, an axially shiftable ferromagnetic rotatable pump wheel, and an electromagnetic wet friction clutch arrangement. The pump wheel is axially shiftable with respect to the rotor shaft and the pump frame. The clutch arrangement comprises a static electromagnet, a clutch disk co-rotatably supported by the rotor shaft, a first clutch friction surface arranged at the clutch disk and a thereto corresponding second clutch friction surface arranged at the pump wheel, and a separate stop friction surface arranged at the pump wheel and a thereto corresponding static stop friction surface arranged at the static pump frame. The electromagnet, when fully energized, axially attracts the pump wheel so that the separate stop friction surface and the static stop friction surface engage to stop the pump wheel.

What is claimed is: 
     
         1 - 11 . (canceled) 
     
     
         12 : A mechanical switchable automotive coolant pump for providing a liquid coolant for an automotive engine, the mechanical switchable automotive coolant pump comprising:
 a static pump frame;   a rotor shaft configured to rotate, the rotor shaft being rotatably supported at the static pump frame;   a pulley wheel configured to be co-rotatably fixed to the rotor shaft and to be mechanically driven by the automotive engine;   a pump wheel comprising a ferromagnet, the pump wheel being configured to rotate and to be axially shiftable, and to be rotatably supported and axially shiftable with respect to each of the rotor shaft and the static pump frame; and   an electromagnetic wet friction clutch arrangement comprising,
 a static electromagnet configured to be energized, 
 a clutch disk which is co-rotatably supported by the rotor shaft, 
 a first clutch friction surface arranged at the clutch disk, 
 a second clutch friction surface arranged at the pump wheel, the first clutch friction surface corresponding to the second clutch friction surface, 
 a separate stop friction surface arranged at the pump wheel, and 
 a static stop friction surface arranged at the static pump frame, the separate stop friction surface corresponding to the static stop friction surface, 
 wherein, 
 the static electromagnet, when fully energized, axially attracts the pump wheel so that the separate stop friction surface and the static stop friction surface engage with each other, thereby stopping the pump wheel. 
   
     
     
         13 : The mechanical switchable automotive coolant pump as recited in  claim 12 , further comprising:
 a preload spring configured to axially preload the clutch disk into an engaged clutch position.   
     
     
         14 : The mechanical switchable automotive coolant pump as recited in  claim 12 , wherein the clutch disk is ferromagnetic and is supported to be axially shiftable at the rotor shaft so that the clutch disk is axially attracted by the electromagnet when energized. 
     
     
         15 : The mechanical switchable automotive coolant pump as recited in  claim 14 , wherein the pump wheel further comprises a non-ferromagnetic pump wheel body which comprises pump blades and with a separate ferromagnetic clutch ring which is fixed to the non-ferromagnetic pump wheel body. 
     
     
         16 : The mechanical switchable automotive coolant pump as recited in  claim 15 , wherein the second clutch friction surface and the separate stop friction surface are arranged at the separate ferromagnetic clutch ring. 
     
     
         17 : The mechanical switchable automotive coolant pump as recited in  claim 12 , further comprising an axial stop surface configured to axially stop the clutch disk in a disengaged clutch position. 
     
     
         18 : The mechanical switchable automotive coolant pump as recited in  claim 12 , wherein the separate stop friction surface and the static stop friction surface are configured to lie in a transversal plane. 
     
     
         19 : The mechanical switchable automotive coolant pump as recited in  claim 15 , further comprising:
 a first electromagnetic gap between the separate ferromagnetic clutch ring and the clutch disk,   a second electromagnetic gap between the separate ferromagnetic clutch ring and the static electromagnet, and   a third electromagnetic gap between the clutch disk and the static electromagnet,   wherein,   the first electromagnetic gap is at least two times larger than the second electromagnetic gap and the third electromagnetic gap.   
     
     
         20 : The mechanical switchable automotive coolant pump as recited in  claim 19 , wherein the first electromagnetic gap is at least 1.0 mm. 
     
     
         21 : The mechanical switchable automotive coolant pump as recited in  claim 19 , wherein the pump wheel further comprises a separate non-ferromagnetic friction ring which is arranged in the first electromagnetic gap between the separate ferromagnetic clutch ring and the clutch disk. 
     
     
         22 : The mechanical switchable automotive coolant pump as recited in  claim 12 , further comprising:
 an electronic clutch control,   wherein,   the electronic clutch control is configured to fully energize the static electromagnet so as to obtain a full-engagement-state where the pump wheel is stopped, and   the electronic clutch control is configured to partially energize the static electromagnet so as to obtain an intermediate-engagement-state where the pump wheel is not completely stopped.