Vane pump with one or more less restricted vanes

Abstract

A vane pump that employs one or more less restricted vanes (or looser vanes) within its rotor is described herein. The less restricted vane(s) are configured to radially move outwardly before the remaining vanes during startup. In one case, for example, at least one vane has a different thickness (e.g., thinner) as compared to the thickness of the remaining vanes. In another case, at least one slot has a different width (e.g., wider) as compared to the width of the other slots. The less restricted vane facilitates a cold start in highly viscous oil by allowing easier radial displacement and thus earlier initial build-up of pressure in the pump. The pump may be used with an engine or transmission.

What is claimed is: 
     
         1 . A vane pump comprising:
 an inlet for receiving fluid from a source;   an outlet for delivering pressurized fluid to a system therefrom;   a pressure chamber cam having an internal space defined by an inside surface and communicated to the inlet and outlet;   a rotor rotatably received within the internal space of the pressure chamber cam, the rotor having a plurality of radial slots and a plurality of vanes received and movable within respective radial slots radially towards the inside surface of the pressure chamber cam; and   a drive shaft connected to the rotor for rotating the rotor to cause the vanes to draw lubricant in from the inlet and pressurize the lubricant for expelling out through the outlet;   the rotor having the radial slots thereof communicated to the pressurized fluid to bias the vanes radially outward therefrom using the fluid pressure;   wherein, for at least one of the plurality of vanes, a distance between an outer face of the at least one vane and an inner face of its respective slot is greater than distances between outer faces of the remaining vanes and inner faces of their respective slots to facilitate radially outward movement thereof towards the inside surface of the pressure chamber cam by centrifugal force during initial start-up of the pump.   
     
     
         2 . The vane pump according to  claim 1 , wherein at least one of the plurality of vanes in the rotor has a lower thickness relative to thicknesses of the remaining vanes to facilitate radially outward movement thereof towards the inside surface of the pressure chamber cam by centrifugal force during initial start-up of the pump. 
     
     
         3 . The vane pump according to  claim 1 , wherein at least one of the plurality of radial slots in the rotor has a higher width relative to widths of other slots, such that the respective vane received within the at least one radial slot of different width is configured for radially outward movement towards the inside surface of the pressure chamber cam by centrifugal force during initial start-up of the pump. 
     
     
         4 . The vane pump according to  claim 2 , wherein each of the plurality of vanes has essentially the same radial length. 
     
     
         5 . The vane pump according to  claim 2 , wherein each of the plurality of vanes has essentially the same height. 
     
     
         6 . The vane pump according to  claim 2 , wherein at least two of the plurality of vanes in the rotor have the lower thickness relative to the thicknesses of the remaining vanes to facilitate radially outward movement towards the inside surface of the pressure chamber cam by centrifugal force during the initial start-up of the pump. 
     
     
         7 . The vane pump according to  claim 6 , wherein the at least two vanes have the same thickness. 
     
     
         8 . The vane pump according to  claim 2 , wherein less than half of the plurality of vanes in the rotor have the lower thickness relative to the thicknesses of the remaining vanes, and wherein the less than half of the plurality of vanes have the same thickness. 
     
     
         9 . The vane pump according to  claim 3 , wherein each of the plurality of slots has essentially the same radial length. 
     
     
         10 . The vane pump according to  claim 3 , wherein each of the plurality of vanes has essentially the same thickness. 
     
     
         11 . The vane pump according to  claim 3 , wherein at least two of the plurality of slots in the rotor have the higher width relative to widths of the other slots, such that the at least two vanes are configured for radially outward movement towards the inside surface of the pressure chamber cam by centrifugal force during initial start-up of the pump. 
     
     
         12 . The vane pump according to  claim 11 , wherein the at least two slots have essentially the same width. 
     
     
         13 . The vane pump according to  claim 9 , wherein less than half of the plurality of slots in the rotor have a different width relative to widths of the other slots, and wherein the less than half of the plurality of slots have the same width. 
     
     
         14 . The vane pump according to  claim 1 , further comprising a first plate and a second plate provided on either side of the pressure chamber cam, wherein the drive shaft extends through the first plate and into the internal space of the pressure chamber cam. 
     
     
         15 . The vane pump according to  claim 14 , wherein the drive shaft is further connected to the second plate. 
     
     
         16 . The vane pump according to  claim 2 , wherein the lower thickness of the at least one of the plurality of vanes is between approximately 0.02 mm and approximately 0.100 mm thinner than the thicknesses of the remaining vanes. 
     
     
         17 . The vane pump according to  claim 3 , wherein the higher width of the at least one radial slot is between approximately 0.02 mm and approximately 0.100 mm higher than the widths of the other slots. 
     
     
         18 . The vane pump according to  claim 1 , wherein the system is a transmission or an engine. 
     
     
         19 . A system comprising:
 an engine or a transmission, and   a vane pump, the vane pump comprising:
 an inlet for receiving fluid from a source; 
 an outlet for delivering pressurized fluid to the engine or transmission; 
 a pressure chamber cam having an internal space defined by an inside surface and communicated to the inlet and outlet; 
 a rotor rotatably received within the internal space of the pressure chamber cam, the rotor having a plurality of radial slots and a plurality of vanes received and movable within respective radial slots radially towards the inside surface of the pressure chamber cam; and 
 a drive shaft connected to the rotor for rotating the rotor to cause the vanes to draw lubricant in from the inlet and pressurize the lubricant for expelling out through the outlet; 
 the rotor having the radial slots thereof communicated to the pressurized fluid to bias the vanes radially outward therefrom using the fluid pressure; 
 wherein, for at least one of the plurality of vanes, a distance between an outer face of the at least one vane and an inner face of its respective slot is greater than distances between outer faces of the remaining vanes and inner faces of their respective slots to facilitate radially outward movement thereof towards the inside surface of the pressure chamber cam by centrifugal force during initial start-up of the pump. 
   
     
     
         20 . The system according to  claim 19 , wherein at least one of the plurality of vanes in the rotor has a lower thickness relative to thicknesses of the remaining vanes to facilitate radially outward movement thereof towards the inside surface of the pressure chamber cam by centrifugal force during initial start-up of the pump. 
     
     
         21 . The system according to  claim 19 , wherein at least one of the plurality of radial slots in the rotor has a higher width relative to widths of other slots, such that the respective vane received within the at least one radial slot of different width is configured for radially outward movement towards the inside surface of the pressure chamber cam by centrifugal force during initial start-up of the pump.