Reduction of cavitation in fuel pumps

Abstract

A fluid gear pump gear arranged to rotate about a first axis. The fluid gear pump gear includes a concentrically disposed first hub portion and a plurality of first teeth radially projecting and circumferentially spaced about the first hub portion, the first hub portion and the first teeth being coated with a vapor-deposited of cavitation resistant coating. The gear also includes a first shaft on which the first hub portion is carried.

What is claimed is: 
     
         1 . A fluid gear pump comprising:
 a first gear constructed and arranged to rotate about a first axis, the first gear including a concentrically disposed first hub portion and a plurality of first teeth radially projecting and circumferentially spaced about the first hub portion, the first teeth being coated with a vapor-deposited of cavitation resistant coating;   a second gear operably coupled to the first gear for rotation about a second axis, the second gear including a concentrically disposed second hub portion and a plurality of second teeth radially projecting and circumferentially spaced about the second hub portion, wherein at a time in operation the plurality of first teeth and the plurality of second teeth contact at first contact point and a second contact point to create a backlash volume interposed between the first contact point and the second contact point;   a first bearing abutting and coaxial to the first hub portion; and   a second bearing abutting and coaxial to the second hub portion.   
     
     
         2 . The fluid gear pump as set forth in  claim 1 , wherein the coating is deposited by filter arc deposition. 
     
     
         3 . The fluid gear pump as set forth in  claim 2 , wherein the coating is nickel titanium (NiTi). 
     
     
         4 . The fluid gear pump as set forth in  claim 1 , wherein the coating is deposited by chemical vapor deposition (CVD) or physical vapor deposition (PVD). 
     
     
         5 . The fluid gear pump as set forth in  claim 4 , wherein the coating is at least one of titanium nitride, titanium aluminium nitride (TiAlN), titanium aluminum silicon nitride or a tungsten containing material. 
     
     
         6 . The fluid gear pump as set forth in  claim 1 , wherein the coating is a diamond-like carbon 
     
     
         7 . The fluid gear pump set forth in  claim 1 , further comprising:
 a first shaft on which the first gear is carried; and   a second shaft on which the second gear is carried;   wherein the second gear is coated with the vapor-deposited of cavitation resistant coating.   
     
     
         8 . The fluid gear pump as set forth in  claim 7 , further comprising a third gear carried on the second shaft. 
     
     
         9 . The fluid gear pump as set forth in  claim 8 , wherein one or more of the first, second and third gears include a nickel titanium coating thereon. 
     
     
         10 . A method of reducing cavitation during fluid gear pump operation, the method comprising:
 rotating a first gear around first axis, the first gear including a concentrically disposed first hub portion and a plurality of first teeth radially projecting and circumferentially spaced about the first hub portion, wherein the first teeth are coated with a vapor-deposited of cavitation resistant coating;   rotating a second gear coupled to the first gear about a second axis, the second gear including a concentrically disposed second hub portion and a plurality of second teeth radially projecting and circumferentially spaced about the second hub portion, wherein the plurality of first teeth engage the plurality of second teeth; and   transferring fluid from a low pressure side to a high pressure side when the first gear is rotating and the second gear is rotating.   
     
     
         11 . A method as set forth in  claim 10 , wherein the first gear is coated with nickel titanium. 
     
     
         12 . A method as set forth in  claim 11 , wherein the first gear is coated with one of: titanium nitride, titanium aluminium nitride (TiAlN), titanium aluminum silicon nitride, tungsten or tungsten carbide, or a diamond-like carbon. 
     
     
         13 . A fluid gear pump gear arranged to rotate about a first axis, the fluid gear pump gear comprising:
 a concentrically disposed first hub portion and a plurality of first teeth radially projecting and circumferentially spaced about the first hub portion, the first hub portion and the first teeth being coated with a vapor-deposited of cavitation resistant coating; and   a first shaft on which the first hub portion is carried   
     
     
         14 . The fluid gear pump gear of  claim 13 , wherein the first gear is coated with nickel titanium. 
     
     
         15 . A fluid gear pump gear of  claim 13 , wherein the first gear is coated with one of: titanium nitride, titanium aluminium nitride (TiAlN), titanium aluminum silicon nitride, tungsten or tungsten carbide, or a diamond-like carbon. 
     
     
         16 . The fluid gear pump gear as set forth in  claim 15 , further comprising a second gear carried on the first shaft.