Metered pulse pump

Abstract

A metering pulse pump for metering an additive liquid into a liquid carrier under high pressure includes a rapidly reciprocating piston pump having a number of pumping chambers and having an inlet connectable to a source of liquid and an outlet, and an outlet line carrying liquid from the outlet under high pressure; a source of additive liquid; a differential piston pump having an inlet connectable to the source of additive liquid, an inlet check valve, a pumping chamber, an outlet check valve, and an outlet connected to the outlet line; and a connection from one of the reciprocating pump pumping chambers to the differential piston pump feeding high-pressure liquid to start the pumping stroke of the differential piston pump. In one embodiment, a spring is used to return the differential piston on its intake stroke. In a second embodiment, a connection from another of the reciprocating pump pumping chambers, which is out of phase with the first chamber, is used to return the differential piston on its intake stroke.

1 . A metering pulse pump for metering an additive liquid into a liquid carrier under high pressure, the pump comprising: 
 (a) a rapidly reciprocating piston pump having a plurality of pumping chambers and having an inlet connectable to a source of liquid and an outlet, and an outlet line carrying liquid from the outlet under high pressure;    (b) a source of additive liquid;    (c) a differential piston pump having an inlet connectable to the source of additive liquid, an inlet check valve, a pumping chamber, an outlet check valve, and an outlet connected to the outlet line; and    (d) a connection from one of the plurality of reciprocating pump pumping chambers to the differential piston pump feeding high-pressure liquid to start the pumping stroke of the differential piston pump.    
   
   
       2 . The apparatus of  claim 1 , wherein the differential piston pump further comprises a differential piston having a first portion and a second portion, the differential piston reciprocating in a chamber, the first portion having a larger surface area than the second portion.  
   
   
       3 . The apparatus of  claim 2 , further comprising a spring biasing the differential piston pump toward its return stroke.  
   
   
       4 . The apparatus of  claim 3 , wherein high-pressure liquid from one of the plurality of reciprocating pump pumping chambers engages the first portion and wherein high-pressure liquid in the outlet line engages the second portion, the difference in surface areas between the first portion and the second portion biasing the differential piston to pump the additive liquid into the outlet line.  
   
   
       5 . The apparatus of  claim 1 , further comprising a connection from another of the plurality of reciprocating pump pumping chambers to the differential piston pump feeding high-pressure liquid to start the return stroke of the differential piston pump.  
   
   
       6 . The apparatus of  claim 5 , wherein the first portion is engaged by liquid from one of the plurality of reciprocating pump pumping chambers, the second portion engages liquid from another of the plurality of reciprocating pump pumping chambers, and wherein liquid pressures in each of the reciprocating pump pumping chambers vary inversely.  
   
   
       7 . The apparatus of  claim 4 , wherein the first portion directly contacts high-pressure liquid from one of the plurality of reciprocating pump pumping chambers.  
   
   
       8 . The apparatus of  claim 7 , wherein the second portion directly contacts high-pressure liquid in the outlet line.  
   
   
       9 . In a rapidly reciprocating piston pump having a plurality of pumping chambers and having an inlet connectable to a source of liquid and an outlet, and an outlet line carrying liquid from the outlet under high pressure, the improvement comprising: 
 (a) a source of additive liquid;    (b) a differential piston pump having an inlet connectable to the source of additive liquid, an inlet check valve, a pumping chamber, an outlet check valve, and an outlet connected to the outlet line; and    (c) a connection from one of the plurality of reciprocating pump pumping chambers to the differential piston pump feeding high-pressure liquid to start the pumping stroke of the differential piston pump.    
   
   
       10 . The apparatus of  claim 9 , wherein the differential piston pump further comprises a differential piston having a first portion and a second portion, the differential piston reciprocating in a chamber, the first portion having a larger surface area than the second portion.  
   
   
       11 . The apparatus of  claim 10 , further comprising a spring biasing the differential piston pump toward its return stroke.  
   
   
       12 . The apparatus of  claim 11 , wherein high-pressure liquid from one of the plurality of reciprocating pump pumping chambers engages the first portion and wherein high-pressure liquid in the outlet line engages the second portion, the difference in surface areas between the first portion and the second portion biasing the differential piston to pump the additive liquid into the outlet line.  
   
   
       13 . The apparatus of  claim 10 , further comprising a connection from another of the plurality of reciprocating pump pumping chambers to the differential piston pump feeding high-pressure liquid to start the return stroke of the differential piston pump.  
   
   
       14 . The apparatus of  claim 13 , wherein the first portion is engaged by high-pressure liquid from one of the plurality of reciprocating pump pumping chambers, the second portion engages high-pressure liquid from another of the plurality of reciprocating pump pumping chambers, and wherein liquid pressures in each of the reciprocating pump pumping chambers vary inversely.