Variable displacement lubricant pump

Abstract

A lubricant pump includes a housing having a shiftable control ring which radially confines a pumping chamber, an outlet chamber, a rotor, a pumping chamber pressure section, and a slide bearing. An interface between the outlet chamber and the control ring defines an outside pressure surface of the control ring. An interface between the pumping chamber pressure section and the control ring defines an inside pressure surface of the control ring. The slide bearing supports the control ring within the housing and includes a first slide bearing surface defined by the housing and which extends in a slide plane, and a second slide bearing surface defined by the control ring. An outside projection area defined by an orthographic projection of the outside pressure surface onto the slide plane is smaller than a maximum inside projection area defined by an orthographic projection of the inside pressure surface onto the slide plane.

What is claimed is: 
     
         1 - 5 . (canceled) 
     
     
         6 . A variable displacement lubricant pump for providing a pressurized lubricant, the variable displacement lubricant pump comprising:
 a static pump housing;   a control ring which is arranged within the static pump housing, the control ring being configured to be shiftable and to radially confine a pumping chamber which is configured to be substantially cylindrical, the control ring comprising a radial outside, an inside pressure surface, and an outside pressure surface;   an outlet chamber which is partially confined by the radial outside of the control ring, an interface between the outlet chamber and the control ring defining the outside pressure surface of the control ring;   a rotatable pump rotor which is arranged within the pumping chamber, the rotatable pump rotor comprising a plurality of rotor vanes which define a plurality of pumping chamber compartments;   a pumping chamber pressure section which is defined by those pumping chamber compartments of the plurality of pumping chamber compartments which are directly fluidically connected with the outlet chamber via a discharge opening, an interface between the pumping chamber pressure section and the control ring defining the inside pressure surface of the control ring; and   a slide bearing which is arranged to adjoin the outlet chamber and which is configured to shiftably support the control ring within the static pump housing, the slide bearing comprising,
 a first slide bearing surface which is defined by the static pump housing and which extends in a slide plane, and 
 a second slide bearing surface which is defined by the control ring, 
   wherein,   an outside projection area is defined by an orthographic projection of the outside pressure surface onto the slide plane,   a maximum inside projection area is defined by an orthographic projection of the inside pressure surface onto the slide plane, and   the outside projection area is smaller than the maximum inside projection area.   
     
     
         7 . The variable displacement lubricant pump as recited in  claim 6 , wherein,
 a minimum inside projection area is defined by the orthographic projection of the inside pressure surface onto the slide plane, and   the outside projection area is smaller compared to the minimum inside projection area.   
     
     
         8 . The variable displacement lubricant pump as recited in  claim 6 , wherein,
 a pumping chamber centerline extends parallel to the slide plane, and   the outside pressure surface is arranged completely at an outlet-sided lateral side of the pumping chamber centerline.   
     
     
         9 . The variable displacement lubricant pump as recited in  claim 8 , wherein the outside pressure surface is arranged within an angular range of 45° to 135° with respect to a pumping chamber center starting at the pumping chamber centerline. 
     
     
         10 . The variable displacement lubricant pump as recited in in  claim 6 , further comprising:
 a control chamber which is configured to hydraulically control a position of the control ring,   wherein,   the slide bearing is configured to fluidically separate the outlet chamber and the control chamber.