Controllable coolant pump

Abstract

A controllable coolant pump for a coolant circuit of an internal combustion engine, the coolant pump including a hollow bearing shaft which is supported in a bearing sleeve, carries a drive wheel at one end, and is permanently connected at its opposite end to an impeller, the impeller having a stop surface at the end face thereof; the space between the stop surface and the impeller forming the pumping cross section for a coolant, and a piston that can be axially displaced by an actuation unit being disposed in the hollow bearing shaft and provided at its outer end with a guide plate having a collar facing the impeller for completely or partially closing the pumping cross section in accordance with the position of the piston. The actuation unit has a release lever which can be pivoted by an electromechanical actuating element about an axis of rotation, thus allowing axial positioning of the piston.

1 - 10 . (canceled) 
     
     
         11 . A controllable coolant pump for a coolant circuit of an internal combustion engine, the coolant pump comprising:
 a hollow bearing shaft supported in a bearing sleeve and carrying a drive wheel at one end, the hollow bearing shaft being permanently connected at an opposite end to an impeller, the impeller having a stop surface at the end face thereof; the space between the stop surface and the impeller forming the pumping cross section for a coolant; and   a piston axially displaceable by an actuation unit disposed in the hollow bearing shaft and provided at an outer end with a guide plate having a collar facing the impeller for completely or partially closing the pumping cross section in accordance with the position of the piston,   the actuation unit having a release lever pivotable by an electromechanical actuating element about an axis of rotation to permit axial positioning of the piston.   
     
     
         12 . The controllable coolant pump as recited in  claim 11  wherein the release lever is pivoted at the bearing sleeve. 
     
     
         13 . The controllable coolant pump as recited in  claim 11  wherein the release lever has a first lever arm and a second lever arm, and an axial bearing is provided between the second lever arm of the release lever and the piston. 
     
     
         14 . The controllable coolant pump as recited in  claim 13  wherein the axial bearing includes two disks having rolling elements disposed therebetween. 
     
     
         15 . The controllable coolant pump as recited in  claim 13  wherein the second lever arm of the release lever has two spaced-apart end portions engaging the axial bearing. 
     
     
         16 . The controllable coolant pump as recited in  claim 15  wherein the two-spaced-apart end sections engage a disk of the axial bearing. 
     
     
         17 . The controllable coolant pump as recited in  claim 11  wherein the electromechanical actuating element has an axially displaceable lead screw acting upon the release lever. 
     
     
         18 . The controllable coolant pump as recited in  claim 17  wherein the lead screw is coupled to a lead screw nut driven by an electric motor. 
     
     
         19 . The controllable coolant pump as recited in  claim 18  wherein the electric motor has a pinion meshing with the lead screw nut. 
     
     
         20 . The controllable coolant pump as recited in  claim 19  wherein the coolant pump includes a second electromechanical actuating element for pivoting the release lever, the second electromechanical actuating element being independent of the first electromechanical actuating element. 
     
     
         21 . The controllable coolant pump as recited in  claim 11  further comprising a sensor for detecting the axial position of the piston.