Vane pump inlet window shape

Abstract

A vane pump has an inlet window and a discharge window formed within a cam surface. The vane pump includes a rotor carrying a plurality of radially extending vanes which are biased into contact with the cam surface. The rotor has a direction of rotation such that one end of the inlet window can be described as an upstream end, and an opposed end as a downstream end. The inlet window extends for a relatively long width along a rotational axis of the rotor at the upstream end. Angularly inwardly extending sides reduce an axial width of the inlet window in a direction moving in a downstream direction from the upstream end.

1 . A vane pump comprising:
 an inlet window and a discharge window, said inlet window being formed within a cam surface;   a rotor carrying a plurality of radially extending vanes which are in contact with said cam surface, said rotor having a direction of rotation such that one end of said inlet window in an upstream end, and an opposed end is a downstream end; and   said upstream end of said inlet window extends generally for a width measured along a rotational axis of said rotor, and there being angularly extending sides which reduce the width of said inlet window in a direction moving towards said downstream end from said upstream end.   
     
     
         2 . The vane pump as set forth in  claim 1 , wherein said upstream end of said inlet window extends parallel to said rotational axis of said rotor. 
     
     
         3 . The vane pump as set forth in  claim 1 , wherein said angularly extending sides merge into a circular section at said downstream end. 
     
     
         4 . The vane pump as set forth in  claim 3 , wherein parallel side portions are positioned between said upstream end and said angularly extending sides. 
     
     
         5 . The vane pump as set forth in  claim 3 , wherein there are curved portions connecting said upstream end to said parallel side portions. 
     
     
         6 . The vane pump as set forth in  claim 3 , wherein said circular section is a complex section having two circular sub-sections. 
     
     
         7 . The vane pump as set forth in  claim 1 , wherein there are two sets of angularly extending sides. 
     
     
         8 . The vane pump as set forth in  claim 7 , wherein a first set of angularly extending sides extend angularly inwardly at a first angle that is greater than a second angle of a second set of angularly extending sides which are positioned downstream of said first set of angularly extending sides. 
     
     
         9 . The vane pump as set forth in  claim 8 , wherein said first and second angles extend axially toward an opposed side in each said set, and are measured from a plane extending parallel to said rotational axis, and wherein said first angle is at least twice as large as said second angle. 
     
     
         10 . The vane pump as set forth in  claim 9 , wherein said first angle is at least four times as large as said second angle. 
     
     
         11 . The vane pump as set forth in  claim 1 , wherein said inlet window is formed in a vane pump liner. 
     
     
         12 . A vane pump comprising:
 a liner body an inlet window and a discharge window, said inlet window being formed within a cam surface;   a rotor carrying a plurality of radially extending vanes which are in contact with said cam surface, said rotor having a direction of rotation such that one end of said inlet window in an upstream end, and an opposed end is a downstream end;   said upstream end of said inlet window extending for a width measured along a rotational axis of said rotor and parallel to said rotational axis, and there being angularly extending sides which reduce the axial width of said inlet window in a direction moving towards said downstream end from said upstream end;   said angularly extending sides merging into a circular section at said downstream end;   parallel side portions positioned between said upstream end and said angularly extending sides; and   curved portions connecting said upstream end to said parallel side portions.   
     
     
         13 . The vane pump as set forth in  claim 12 , wherein said circular section is a complex section having two circular sub-sections. 
     
     
         14 . The vane pump as set forth in  claim 12 , wherein there are two sets of angularly extending sides. 
     
     
         15 . The vane pump as set forth in  claim 14 , wherein a first set of angularly extending sides extend angularly inwardly at a first angle that is greater than a second angle of a second set of angularly extending sides which are positioned downstream of said first set of angularly extending sides. 
     
     
         16 . The vane pump as set forth in  claim 15 , wherein said first and second angles extend axially toward an opposed side in each said set, and measured from a plane extending parallel to said rotational axis, and wherein said first angle is at least twice as large as said second angle. 
     
     
         17 . The vane pump as set forth in  claim 16 , wherein said first angle is at least four times as large as said second angle.