Pump

Abstract

A pump includes a main body having upper and lower body parts that confine a chamber and an inlet, respectively, an inlet valve including a valve seat and a ball member seated movably on the valve seat to block fluid communication between the inlet and the chamber, a delivery shaft including a valve-control segment and a delivery segment that is formed with a channel to be disposed in fluid communication with the chamber, a piston disposed movably in the chamber, an elastic component disposed in the main body for providing a biasing force to move the valve-control segment of the delivery shaft away from the inlet valve, and a delivery tube operable to drive movement of the delivery shaft toward the inlet valve such that the valve-control segment forces the ball member to be seated on the valve seat.

1 . A pump comprising: 
 a tubular main body extending along an axis and having an upper body part confining a chamber, and a lower body part connected to said upper body part and confining an inlet distal from said upper body part;    an inlet valve including a valve seat formed in said lower body part, and a ball member disposed in said lower body part and seated movably on said valve seat to block fluid communication between said inlet and said chamber;    a delivery shaft extending through said upper body part into said chamber along said axis, and including an upper delivery segment, a lower valve-control segment, and a piston-seating segment disposed between said delivery and valve-control segments, said delivery segment being formed with a channel to be disposed in fluid communication with said chamber;    a piston disposed movably in said chamber and including a sleeve portion sleeved on said delivery segment of said delivery shaft, a peripheral portion disposed around said sleeve portion and in sealing contact with said upper body part, and a connecting portion that interconnects said sleeve and peripheral portions;    an elastic component disposed in said main body for providing a biasing force to move said valve-control segment of said delivery shaft away from said inlet valve, and to cause said piston-seating segment of said delivery shaft to push said sleeve portion of said piston away from said inlet valve; and    a delivery tube sleeved on said delivery segment of said delivery shaft and operable to drive movement of said delivery shaft toward said inlet valve such that said valve-control segment of said delivery shaft forces said ball member to be seated on said valve seat, and to drive movement of said piston toward said inlet valve.    
   
   
       2 . The pump as claimed in  claim 1 , wherein fluid communication between said channel and said chamber is prevented when said piston-seating segment of said delivery shaft abuts against said sleeve portion of said piston, 
 pressure in said chamber when said piston is driven by said delivery tube toward said inlet valve causing said sleeve portion of said piston to move away from said piston-seating segment of said delivery shaft to permit fluid communication between said channel and said chamber.    
   
   
       3 . The pump as claimed in  claim 1 , wherein said upper body part has a larger cross-section than that of said lower body part, 
 said main body further having a shoulder part between said upper and lower body parts, said shoulder part cooperating with said piston-seating segment of said delivery shaft to limit movement of said delivery shaft toward said inlet valve upon operation of said delivery tube.    
   
   
       4 . The pump as claimed in  claim 1 , wherein said delivery segment of said delivery shaft has an outer surface, and said channel includes at least three fluid ducts that extend parallel to said axis, that are angularly spaced apart from each other relative to said axis, and that are indented from said outer surface of said delivery segment toward said axis.  
   
   
       5 . The pump as claimed in  claim 1 , wherein said channel extends along said axis, and said delivery segment is further formed with a radial port to communicate fluidly said channel and said chamber.  
   
   
       6 . The pump as claimed in  claim 1 , wherein said elastic component is a compression spring sleeved on said valve-control segment of said delivery shaft and having opposite ends that abut against said lower body part of said main body and said piston-seating segment of said delivery shaft, respectively.