Variable displacement lubricant pump

Abstract

A variable displacement lubricant pump for providing a pressurized lubricant for an internal combustion engine. The variable displacement lubricant pump includes a shiftable control ring, a pump rotor comprising a plurality of slidable vanes which rotate in the control ring, a hydraulic pressure control comprising a control chamber which comprises a lateral control chamber wall, and a control ring plunger shiftable along the lateral control chamber wall, a first eccentricity limiting opening arranged in the lateral control chamber wall, a second eccentricity limiting opening arranged in the lateral control chamber wall, and an eccentricity limiting control system which connects or disconnects the first eccentricity limiting opening and the second eccentricity limiting opening to atmospheric pressure dependent on a lubricant temperature. The hydraulic pressure control directly actuates and controls an eccentricity of the control ring.

What is claimed is: 
     
         1 - 7 . (canceled) 
     
     
         8 . A variable displacement lubricant pump for providing a pressurized lubricant for an internal combustion engine, the variable displacement lubricant pump comprising:
 a control ring configured to be shiftable;   a pump rotor comprising a plurality of slidable vanes which are configured to rotate in the control ring;   a hydraulic pressure control comprising a control chamber which comprises a lateral control chamber wall, and a control ring plunger configured to be shiftable along the lateral control chamber wall, the hydraulic pressure control being configured to directly actuate and to control an eccentricity of the control ring;   a first eccentricity limiting opening arranged in the lateral control chamber wall;   a second eccentricity limiting opening arranged in the lateral control chamber wall; and   an eccentricity limiting control system configured to connect or disconnect the first eccentricity limiting opening and the second eccentricity limiting opening to atmospheric pressure dependent on a lubricant temperature.   
     
     
         9 . The variable displacement lubricant pump as recited in  claim 8 , further comprising a third eccentricity limiting opening arranged in the lateral control chamber wall. 
     
     
         10 . The variable displacement lubricant pump as recited in  claim 9 , wherein the eccentricity limiting control system comprises at least one bimetal element configured to open or close at least one of the first eccentricity limiting opening, the second eccentricity limiting opening, and the third eccentricity limiting opening. 
     
     
         11 . The variable displacement lubricant pump as recited in  claim 9 , wherein,
 the first eccentricity limiting opening comprises a first bimetal element configured to close the first eccentricity limiting opening in a closed position of the first bimetal element,   the second eccentricity limiting opening comprises a second bimetal element configured to close the second eccentricity limiting opening in a closed position of the second bimetal element, and   the second eccentricity limiting opening comprises a third bimetal element configured to close the third eccentricity limiting opening in a closed position of the third bimetal element.   
     
     
         12 . The variable displacement lubricant pump as recited in  claim 11 , further comprising:
 a fourth bimetal element; and   a separate valve plunger configured to open or close at least one of the first eccentricity limiting opening, the second eccentricity limiting opening, and the third eccentricity limiting opening depending on a position of the separate valve plunger, the separate valve plunger being actuated by the fourth bimetal element.   
     
     
         13 . The variable displacement lubricant pump as recited in  claim 12 , further comprising:
 a preload element;   wherein, the separate valve plunger is preloaded by the preload element into a closed position where each of the first eccentricity limiting opening, the second eccentricity limiting opening, and the third eccentricity limiting opening is closed.   
     
     
         14 . The variable displacement lubricant pump as recited in  claim 8 , wherein a switching temperature TS of the eccentricity limiting control system is between 0° C. and 100° C.