Fixed Displacement Pump

Abstract

A fixed displacement pump. The fixed displacement pump may include a chamber, a piston positioned within the chamber, and a collar positioned within the chamber to as to limit movement of the piston within the chamber.

1 . A fixed displacement pump, comprising:
 a chamber;   a piston positioned within the chamber; and   a collar positioned within the chamber to as to limit movement of the piston within the chamber.   
   
   
       2 . The fixed displacement pump of  claim 1 , further comprising an electric coil surrounding the chamber. 
   
   
       3 . The fixed displacement pump of  claim 1 , further comprising a piston spring in contact with the piston. 
   
   
       4 . The fixed displacement pump of  claim 3 , wherein the collar is positioned outside of the piston spring. 
   
   
       5 . The fixed displacement pump of  claim 3 , wherein the collar is positioned inside of the piston spring. 
   
   
       6 . The fixed displacement pump of  claim 1 , wherein the collar is integral with the chamber. 
   
   
       7 . The fixed displacement pump of  claim 1 , wherein the collar is nonintegral with the chamber. 
   
   
       8 . The fixed displacement pump of  claim 1 , wherein the collar comprises a predetermined length. 
   
   
       9 . The fixed displacement pump of  claim 1 , further comprising a plurality of collars with varying lengths. 
   
   
       10 . A method of retrofitting a variable displacement pump having a chamber and a piston therein, comprising:
 positioning a collar within the chamber;   limiting the extent of a stroke of the piston within the chamber by the collar; and   operating the pump as a fixed displacement pump.   
   
   
       11 . The method of  claim 10 , further comprising determining a desired length of the stroke of the piston. 
   
   
       12 . The method of  claim 11 , wherein the step of positioning the collar comprises positioning a collar of a predetermined length. 
   
   
       13 . A fixed displacement solenoid pump, comprising:
 a chamber;   a piston positioned within the chamber;   a piston spring in contact with the piston; and   a collar positioned within the chamber to as to limit movement of the piston within the chamber.   
   
   
       14 . The fixed displacement solenoid pump of  claim 13 , further comprising an electric coil surrounding the chamber. 
   
   
       15 . The fixed displacement solenoid pump of  claim 13 , wherein the collar is positioned outside of the piston spring. 
   
   
       16 . The fixed displacement solenoid pump of  claim 13 , wherein the collar is positioned inside of the piston spring. 
   
   
       17 . The fixed displacement solenoid pump of  claim 13 , wherein the collar is integral with the chamber. 
   
   
       18 . The fixed displacement solenoid pump of  claim 13 , wherein the collar is nonintegral with the chamber. 
   
   
       19 . The fixed displacement solenoid pump of  claim 13 , wherein the collar comprises a predetermined length. 
   
   
       20 . The fixed displacement pump of  claim 13 , further comprising a plurality of collars with varying lengths.