Pumping mechanism with plunger

Abstract

A pumping mechanism includes a barrel assembly having a plunger bore. The plunger bore has a longitudinal axis. The pumping mechanism also includes a plunger configured to slide within the plunger bore parallel to the longitudinal axis. The pumping mechanism further includes a push rod separate from the plunger. The push rod is configured to move away from the plunger to be spaced from the plunger, and the push rod is further configured to move within the plunger bore to push the plunger.

What is claimed is: 
     
         1 . A pumping mechanism comprising:
 a barrel assembly including a plunger bore, the plunger bore having a longitudinal axis;   a plunger configured to slide within the plunger bore parallel to the longitudinal axis; and   a push rod separate from the plunger, the push rod being configured to move away from the plunger to be spaced from the plunger, the push rod being further configured to move within the plunger bore to push the plunger.   
     
     
         2 . The pumping mechanism of  claim 1 , wherein:
 the plunger is configured to slide in a first direction along the longitudinal axis and a second direction opposite the first direction along the longitudinal axis; and   the push rod is configured to move away from the plunger to allow the plunger to move in the first direction and to push the plunger in the second direction.   
     
     
         3 . The pumping mechanism of  claim 2 , wherein the plunger bore is configured to receive a flow of pressurized fluid to push the plunger in the first direction. 
     
     
         4 . The pumping mechanism of  claim 3 , further including an inlet check valve configured to control flow directed into the plunger bore to push the plunger in the first direction. 
     
     
         5 . The pumping mechanism of  claim 3 , further including an outlet check valve configured to control at least a first portion of the flow of pressurized fluid directed from the plunger bore to an outlet passage in the barrel assembly, the outlet passage having at least a portion that is generally parallel to and separate from the plunger bore. 
     
     
         6 . The pumping mechanism of  claim 5 , wherein the plunger bore is configured to supply a second portion of the flow of pressurized fluid out of the barrel assembly from the plunger bore, the second portion being separate from the first portion of the flow of pressurized fluid. 
     
     
         7 . The pumping mechanism of  claim 1 , wherein:
 the plunger bore includes a proximal end, a distal end having a lateral dimension that is smaller than a lateral dimension of the proximal end, and a transition portion formed at a transition between the proximal end and the distal end of the plunger bore;   the plunger includes a main portion, a distal portion having a lateral dimension that is smaller than a lateral dimension of the main portion, and a shoulder formed at a transition between the main portion and the distal portion; and   the shoulder of the plunger is configured to abut against the transition portion to limit movement of the plunger into the distal end of the plunger bore.   
     
     
         8 . The pumping mechanism of  claim 7 , wherein:
 the transition portion has an edge that is angled with respect to the longitudinal axis, and the shoulder is angled with respect to the longitudinal axis; and   an angle differential between an angle of the edge of the transition portion and an angle of the shoulder is approximately 3° to 6°.   
     
     
         9 . The pumping mechanism of  claim 1 , wherein the plunger is sealless. 
     
     
         10 . A pump comprising:
 a reservoir configured to store a fluid; and   at least one pumping mechanism at least partially disposed in the reservoir, the at least one pumping mechanism including:
 a barrel assembly including a plunger bore, the plunger bore having a longitudinal axis and being fluidly connected to the reservoir, 
 a plunger configured to slide within the plunger bore along the longitudinal axis in a first direction and in a second direction opposite the first direction, and 
 a push rod separate from the plunger, the push rod being configured to move away from the plunger to allow the plunger to move in the first direction, the push rod being further configured to move within the plunger bore to push the plunger in the second direction to direct the fluid to a discharge passage of the pump. 
   
     
     
         11 . The pump of  claim 10 , wherein the plunger bore is configured to receive a flow of pressurized fluid to push the plunger in the first direction. 
     
     
         12 . The pump of  claim 10 , wherein the barrel assembly includes an outlet check valve configured to control an amount of the fluid directed into the discharge passage of the pump. 
     
     
         13 . The pump of  claim 12 , wherein the push rod is configured to push the plunger distally in the plunger bore along the longitudinal axis to direct the fluid past the outlet check valve toward the discharge passage. 
     
     
         14 . The pump of  claim 10 , wherein the barrel assembly includes an inlet check valve configured to control an amount of the fluid entering the plunger bore from the reservoir, and the plunger is configured to move in the first direction in the plunger bore when a pressurized fluid is directed to the plunger bore via the inlet check valve. 
     
     
         15 . A fluid system comprising:
 a storage tank configured to store a fluid;   a pump fluidly connected to the storage tank to receive the fluid;   a boost pump configured to pressurize the fluid to communicate the fluid from the storage tank into the pump;   wherein the pump includes;
 a reservoir configured to store the fluid pressurized by the boost pump; and 
 at least one pumping mechanism at least partially disposed in the reservoir, the at least one pumping mechanism including: 
 a barrel assembly including a plunger bore, the plunger bore having a longitudinal axis and being fluidly connected to the reservoir, 
 a plunger configured to slide within the plunger bore along the longitudinal axis in a first direction and in a second direction opposite the first direction, and 
 a push rod separate from the plunger, the push rod being configured to move away from the plunger to allow the plunger to move in the first direction due to a pressure from the fluid pressurized by the boost pump, the push rod also being configured to move within the plunger bore to push the plunger in the second direction to direct the fluid to a discharge passage of the pump. 
   
     
     
         16 . The fluid system of  claim 15 , wherein the barrel assembly includes an inlet check valve configured to control an amount of the fluid entering the plunger bore from the reservoir. 
     
     
         17 . The fluid system of  claim 16 , wherein the inlet check valve is configured to close when the plunger slides in the second direction. 
     
     
         18 . The fluid system of  claim 15 , wherein the barrel assembly includes an outlet check valve configured to control an amount of the fluid directed to the discharge passage of the pump. 
     
     
         19 . The fluid system of  claim 15 , wherein the plunger bore includes an inlet configured to receive the fluid pressurized by the boost pump and an outlet configured to direct fluid leaking between the plunger and the plunger bore back to the storage tank. 
     
     
         20 . The fluid system of  claim 19 , wherein the plunger is configured to slide in the first direction due to a pressure differential between a pressure acting on a distal end of the plunger and a pressure acting on a proximal end of the plunger, the pressure acting on the distal end of the plunger being generally equal to the pressure of the fluid pressurized by the boost pump, the pressure acting on the proximal end of the plunger being generally equal to a pressure of the fluid in the storage tank.