Ejector having an actuation mechanism with a pilot valve and an equalization passage between two cylinder chambers

Abstract

An ejector ( 1; 100 ), e.g. for a refrigerant circuit, with a primary inlet ( 2 ), a secondary inlet ( 7 ), an outlet ( 12 ), a nozzle ( 5 ), and a mixing portion ( 6, 10 ) includes an actuating mechanism ( 30 ) moving a needle ( 20 ) between an opened position and a closed position. The actuation mechanism ( 30 ) includes a piston ( 31 ) in a cylinder ( 35 ), wherein a first cylinder chamber ( 37 ) is in fluid communication with the primary inlet ( 2 ) and a second cylinder chamber ( 38 ) is in fluid communication with the first cylinder chamber ( 37 ). The second cylinder chamber ( 38 ) is in fluid communication with the secondary inlet ( 7 ) and/or the outlet ( 12 ) via a drain passage ( 39, 53, 54, 55, 56, 57 ) when a pilot valve ( 50 ) arranged in the drain passage ( 39, 53, 54, 55, 56, 57 ) is in an open state. For ensuring smooth opening and closing, the fluid communication of the second cylinder chamber ( 38 ) with the first cylinder chamber ( 37 ) is provided by an equalization passage ( 32 ), wherein a flow cross-section of the equalization passage ( 32 ) is larger than a flow cross-section of the drain passage ( 39, 53, 54, 55, 56, 57 ).

What is claimed is: 
     
         1 . An ejector comprising
 a primary inlet; a secondary inlet; and an outlet;   a nozzle for jetting fluid supplied at the primary inlet into a mixing portion for sucking fluid supplied at the secondary inlet into the mixing portion);   a needle and a needle seat, wherein the needle seat is arranged downstream of the primary inlet and upstream of the nozzle; and   an actuating mechanism for moving the needle between an opened position, in which the needle is lifted from the needle seat for allowing fluid flow past the needle seat, and a closed position, in which the needle abuts the needle seat and blocks fluid flow past the needle seat, wherein the actuating mechanism comprises:   a cylinder with a piston connected to the needle, wherein a first cylinder chamber is maximized when the needle is in its opened position and a second cylinder chamber is maximized when the needle is in its closed position, wherein the first cylinder chamber is in fluid communication with the primary inlet via a chamber inlet, and wherein the second cylinder chamber is in fluid communication with the first cylinder chamber, and   a drain passage with a pilot valve, wherein the second cylinder chamber is in fluid communication with the secondary inlet and/or the outlet via the drain passage when the pilot valve is in an open state,   wherein the fluid communication of the second cylinder chamber with the first cylinder chamber is provided by an equalization passage, wherein a flow cross-section of the equalization passage is larger than a flow cross-section of the drain passage.   
     
     
         2 . The ejector according to  claim 1 , wherein a piston area, which is a cross-section area of the piston, is at least 1000 times the flow cross-section of the equalization passage. 
     
     
         3 . The ejector according to  claim 1 , wherein a needle seat area, which is a cross-section area of the needle seat where the needle engages the needle seat in the closed position, is in the range from 1,005 to 1,4 times a flow cross-section of the nozzle. 
     
     
         4 . The ejector according to  claim 1 , wherein the pilot valve is a solenoid valve. 
     
     
         5 . The ejector according to  claim 1 , wherein the piston area corresponds to at least 20 times the needle seat area. 
     
     
         6 . The ejector according to  claim 1 , wherein a stroke(S) of the needle between the closed position and the opened position correspond to at least 2*(A noz /π) 0,5 , where A noz  is the flow cross-section of the nozzle. 
     
     
         7 . The ejector according to  claim 1 , wherein the ejector includes a check valve for preventing fluid flow from the outlet to the secondary inlet. 
     
     
         8 . The ejector according to  claim 1 , wherein the equalization passage is formed in the piston. 
     
     
         9 . The ejector according to  claim 1 , wherein the flow cross-section of the equalization passage is in the range from 1,2 to 2,5 times the flow cross-section of the drain passage when the pilot valve is in an open state. 
     
     
         10 . The ejector according to  claim 1 , wherein a nozzle inlet is formed directly upstream of the nozzle, wherein the nozzle inlet tapers toward the nozzle, wherein the needle seat is located in the nozzle inlet, and wherein a length (W) of the nozzle inlet corresponds to at least 1,8 times the stroke (S) of the needle between the closed position and the opened position. 
     
     
         11 . The ejector according to  claim 1 , wherein the ejector comprises a resilient member acting against minimizing the second cylinder chamber by the piston. 
     
     
         12 . The ejector according to  claim 1 , wherein the ejector is configured such that an opening time of the needle is at least 0,5 s and/or that a closing time of the needle is at least 1 s. 
     
     
         13 . The ejector according to  claim 1 , wherein the flow cross-section of the nozzle is at least 50 mm 2 . 
     
     
         14 . The ejector according to  claim 1 , wherein the cylinder is formed by a cylinder insert and a top cover, wherein an elastic member biases the cylinder insert in abutment against the top cover. 
     
     
         15 . An ejector assembly comprising at least two ejectors according to  claim 1 .