High pressure seal for a pump system for pumping liquid under high pressure

Abstract

A system for pumping liquid under high pressure includes a housing and a high pressure seal. The housing houses a pump assembly and a chamber assembly that includes a chamber for containing high pressure liquid. The seal separates high pressure area in the chamber assembly from low pressure area in the pump assembly. The seal includes a seal opening that receives a piston that moves axially to increase pressure on the liquid in the chamber; an active sealing area adjacent the chamber; a compressible sealing area adjacent the active sealing area; and a connection channel formed through the compressible sealing area between the seal opening and a leakage space formed between the housing and the high pressure seal. The connection channel conducts the liquid, leaked into the leakage space from the chamber, from the leakage space to the seal opening during operation of the piston, providing lubrication for the piston.

What is claimed is: 
     
         1 . A system for pumping liquid under high pressure, the system comprising:
 a housing configured to house a chamber assembly and a pump assembly, the chamber assembly comprising a chamber for containing a liquid under high pressure;   a high pressure seal separating a high pressure area in the chamber assembly from a low pressure area in the pump assembly, the high pressure seal comprising:
 a seal opening configured to receive a piston operable by the pump assembly and configured to move axially within the seal opening to increases pressure on the liquid in the chamber; 
 an active sealing area adjacent the chamber; 
 a compressible sealing area adjacent the active sealing area; and 
 a connection channel formed through a wall of the compressible sealing area between the seal opening and a leakage space formed between the housing and the high pressure seal, the connection channel being configured to conduct the liquid, leaked into the leakage space from the chamber, from the leakage space to the seal opening during operation of the piston, 
   wherein the liquid conducted from the leakage space to the seal opening provides lubrication for the piston as the piston moves axially within the seal opening.   
     
     
         2 . The system of  claim 1 , wherein the high pressure seal further comprises:
 an axial fixing portion configured to attach the high pressure seal to the housing.   
     
     
         3 . The system of  claim 1 , wherein the compressible sealing area is formed of an elastomeric material. 
     
     
         4 . The system of  claim 3 , wherein the compressible sealing area compresses axially and expands radially as a pressure differential between the high pressure area in the chamber assembly and the low pressure area in the pump assembly increases. 
     
     
         5 . The system of  claim 3 , wherein active sealing area is hydraulically supported. 
     
     
         6 . The system of  claim 5 , wherein active sealing area defines a circumferential spring channel that contains a spring for exerting a radially inward force on the piston in the seal opening and a radially outward force on the housing to enhance sealing of the seal. 
     
     
         7 . The system of  claim 5 , wherein hydraulic resistance of the high pressure seal is adjustable. 
     
     
         8 . The system of  claim 7 , wherein the hydraulic resistance of the high pressure seal is adjustable to between about 1 percent and about 60 percent of pressure in the high pressure area. 
     
     
         9 . The system of  claim 8 , wherein the hydraulic resistance of the high pressure seal is adjustable due to a cross sectional geometry of the connection channel. 
     
     
         10 . The system of  claim 8 , wherein the hydraulic resistance of the high pressure seal is adjustable due to a number of connection channels. 
     
     
         11 . The system of  claim 8 , wherein the hydraulic resistance of the high pressure seal is adjustable due to supports or porous fillings of the connection channel. 
     
     
         12 . The system of  claim 8 , wherein the hydraulic resistance of the high pressure seal is adjustable due to a porous connection between the active sealing area and the compressible sealing area. 
     
     
         13 . The system of  claim 1 , wherein the low pressure area is substantially ambient pressure. 
     
     
         14 . The system of  claim 1 , further comprising:
 a cap contained within the housing in the pump assembly; and   a cap ring contained within the cap, the cap ring being adjacent the compressible sealing area, wherein the compressible sealing area compresses axially against at least the cap ring, holding the high pressure seal in position between the chamber and the pump assembly.   
     
     
         15 . The system of  claim 14 , wherein the cap defines a cap opening and the cap ring defines a cap ring opening, each of the cap opening and the cap ring opening being aligned with the seal opening and configured to receive the piston, and wherein a clearance between the cap ring opening and the piston is tight enough to prevent contact between the cap opening and an outer surface of the piston while operating. 
     
     
         16 . The system of  claim 1 , wherein liquid also leaks from the chamber directly into the seal opening during operation of the piston. 
     
     
         17 . A high pressure seal separating high and low pressure areas in a pump system, the high pressure seal comprising:
 an active sealing area adjacent a chamber containing a liquid under high pressure;   a compressible sealing area adjacent the active sealing area;   a seal opening configured to receive a piston configured to move axially within the seal opening to increases pressure on the liquid in the chamber; and   a connection channel formed through the compressible sealing area, the connection channel being configured to connect the seal opening and a leakage space formed between a seal engagement surface of a housing containing the high pressure seal and a housing abutment surface of the high pressure seal,   wherein a first leakage path enables the liquid to leak directly from the chamber to the seal opening, and   wherein a second leakage path enables the liquid to leak from the chamber to the leakage space, and from the leakage space through the connection channel to the seal opening.   
     
     
         18 . The seal of  claim 17 , wherein the liquid from the first and second leakage paths provides lubrication for the piston as the piston moves axially within the seal opening. 
     
     
         19 . The seal of  claim 17 , wherein the high pressure seal further comprises:
 an axial fixing portion configured to provide a sealing attachment between the high pressure seal and the housing.   
     
     
         20 . The seal of  claim 17 , wherein the active sealing area defines a circumferential spring channel that contains a spring for exerting a radially inward force on a surface of the piston in the seal opening and a radially outward force on the seal engagement surface of the housing to enhance sealing.