High Vacuum Ejector

Abstract

An ejector for generating a vacuum comprising a first stage. The first stage comprises a drive nozzle and a ring drive nozzle. The drive nozzle is for generating a drive jet of air from a flow of compressed air and directing the drive jet of air into a first stage expansion nozzle in order to entrain air in a volume surrounding the drive jet of air into the jet flow to generate a vacuum across the first stage. The ring drive nozzle is for generating a drive ring of air from the flow of compressed air and directing the drive ring of air onto the jet flow and the entrained air, and into an inlet of an exit expansion nozzle.

1 . An ejector for generating a vacuum comprising:
 a first section comprising:   a drive nozzle for generating a drive jet of air from a flow of compressed air and directing the drive jet of air into a first section expansion nozzle in order to entrain air in a volume surrounding the drive jet of air into a jet flow to generate a vacuum across the first section; and   a ring drive nozzle for generating a drive ring of air from the flow of compressed air and directing the drive ring of air onto the jet flow and the entrained air, and into an inlet of an exit expansion nozzle.   
     
     
         2 . The ejector of  claim 1 , wherein the first section expansion nozzle comprises a diverging section, the diverging section of the first section expansion nozzle diverges in a direction of airflow through the first section expansion nozzle. 
     
     
         3 . The ejector of  claim 1 , wherein the drive ring of air is directed over an outlet of the first section expansion nozzle. 
     
     
         4 . The ejector of  claim 3 , wherein the outlet of the first section comprises an outlet of the first section expansion nozzle and an outlet of the ring drive nozzle. 
     
     
         5 . The ejector of  claim 1 , wherein the inlet of the exit expansion nozzle defines a stepwise expansion in the diameters between an outlet of the first section and the inlet of the exit expansion nozzle. 
     
     
         6 . The ejector of  claim 5 , wherein an outlet of the first section expansion nozzle, an outlet of the ring drive nozzle and the stepwise expansion in the diameters between the outlet of the first section and the inlet of the exit expansion nozzle, are aligned along a direction of airflow through the ejector. 
     
     
         7 . The ejector of  claim 1 , wherein the drive ring of air is directed onto the jet flow and the entrained air at the inlet of the exit expansion nozzle. 
     
     
         8 . The ejector of  claim 1 , wherein the exit expansion nozzle comprises a diverging section, the diverging section of the exit expansion nozzle diverges in a direction of airflow through the exit expansion nozzle. 
     
     
         9 . The ejector of  claim 8 , wherein the drive ring of air is directed onto the jet flow and the entrained air at least in the diverging section of the of the exit expansion nozzle. 
     
     
         10 . The ejector of  claim 8 , wherein the diverging section of the exit expansion nozzle defines a stepwise expansion in the diameter of the diverging section. 
     
     
         11 . The ejector of  claim 1 , wherein the exit expansion nozzle comprises a converging section, the converging section of the exit expansion nozzle converges in a direction of airflow through the exit expansion nozzle. 
     
     
         12 . The ejector of  claim 11 , wherein the drive ring of air is directed onto the jet flow and the entrained air at least in the converging section of the of the exit expansion nozzle. 
     
     
         13 . The ejector of  claim 1 , wherein the exit expansion nozzle comprises a straight section, the straight section of the exit expansion nozzle is straight in a direction of airflow through the exit expansion nozzle. 
     
     
         14 . The ejector of  claim 13 , wherein the drive ring of air is directed onto the jet flow and the entrained air at least in the straight section of the of the exit expansion nozzle. 
     
     
         15 . A method of generating a vacuum from a flow of compressed air, comprising:
 supplying the flow of compressed air to a drive nozzle to generate a drive jet of air;   directing the drive jet of air into a first section expansion nozzle;   generating a vacuum by entraining air in a volume surrounding the drive jet of air into a jet flow;   supplying the flow of compressed air to a ring drive nozzle to generate a drive ring of air; and   directing the drive ring of air onto the jet flow and the entrained air, and into an inlet of an exit expansion nozzle.   
     
     
         16 . The method of  claim 15 , wherein the drive ring of air is directed onto the jet flow and the entrained air, and into the inlet of the exit expansion nozzle in order to accelerate the flow of air through the first section expansion nozzle. 
     
     
         17 . The ejector of  claim 9 , wherein the diverging section of the exit expansion nozzle defines a stepwise expansion in the diameter of the diverging section.