Ejector, ejector production method, and method for setting outlet flow path of diffuser

Abstract

An ejector includes a nozzle, a suction chamber, and a diffuser. An outlet flow path includes a narrowed flow path having a first tapered surface narrowed toward downstream, a parallel flow path having a constant sectional area, and a parallel flow path having a second tapered surface expanded toward downstream. The diffuser further includes an attachment configured to change the dimensions of the outlet flow path. The attachment changes the dimensions of the outlet flow path such that the ratio of the tapered angle of the first tapered surface to the tapered angle of the second tapered surface is higher as the sectional area, i.e., the inner diameter, of the parallel flow path is smaller.

What is claimed: 
     
         1 . An ejector comprising:
 a nozzle configured to eject first fluid;   a suction chamber configured to house the nozzle and to suck second fluid by negative pressure generated by ejection of the first fluid from the nozzle; and   a diffuser including an outlet flow path and configured to mix and discharge the first fluid and the second fluid of the suction chamber,   wherein the outlet flow path includes a narrowed flow path having a first tapered surface narrowed toward downstream, a parallel flow path connected to a downstream end of the narrowed flow path and having a constant sectional area, and an expanded flow path connected to a downstream end of the parallel flow path and having a second tapered surface expanded toward downstream,   the diffuser further includes a changing unit configured to change a dimension of the outlet flow path, and   the changing unit changes the dimension of the outlet flow path such that a ratio of a tapered angle of the first tapered surface to a tapered angle of the second tapered surface is higher as the sectional area of the parallel flow path is smaller.   
     
     
         2 . The ejector according to  claim 1 , wherein
 the changing unit changes the dimension of the outlet flow path such that a length of the parallel flow path is shorter as the sectional area of the parallel flow path is smaller.   
     
     
         3 . The ejector according to  claim 2 , wherein
 the changing unit changes the dimension of the outlet flow path such that the length of the parallel flow path changes in proportion to an inner diameter of the parallel flow path.   
     
     
         4 . The ejector according to  claim 1 , wherein
 part of the diffuser is formed from a replaceable attachment,   the changing unit is the attachment,   the attachment includes at least part of the narrowed flow path, the parallel flow path, and at least part of the expanded flow path, and   the dimension of the outlet flow path is changed by replacement of the attachment.   
     
     
         5 . A method for manufacturing an ejector including a nozzle configured to eject first fluid, a suction chamber configured to house the nozzle and to suck second fluid by negative pressure generated by ejection of the first fluid from the nozzle, and a diffuser including an outlet flow path having a narrowed flow path having a first tapered surface narrowed toward downstream, a parallel flow path connected to a downstream end of the narrowed flow path and having a constant sectional area, and an expanded flow path connected to a downstream end of the parallel flow path and having a second tapered surface expanded toward downstream and configured to mix and discharge the first fluid and the second fluid of the suction chamber, comprising:
 a setting step of setting a dimension of the outlet flow path; and   a preparation step of preparing the diffuser having the dimension of the outlet flow path set at the setting step,   wherein at the setting step, the dimension of the outlet flow path is set such that a ratio of a tapered angle of the first tapered surface to a tapered angle of the second tapered surface is higher as the sectional area of the parallel flow path is smaller.   
     
     
         6 . The method for manufacturing the ejector according to  claim 5 , wherein
 at the preparation step, the diffuser having the outlet flow path set at the setting step is prepared by replacement of a replaceable attachment of the diffuser including the attachment.   
     
     
         7 . A method for setting an outlet flow path of a diffuser including an outlet flow path having a narrowed flow path having a first tapered surface narrowed toward downstream, a parallel flow path connected to a downstream end of the narrowed flow path and having a constant sectional area, and an expanded flow path connected to a downstream end of the parallel flow path and having a second tapered surface expanded toward downstream and used for an ejector, comprising:
 a step of setting a sectional area of the parallel flow path; and   a step of setting a dimension of the outlet flow path such that a ratio of a tapered angle of the first tapered surface to a tapered angle of the second tapered surface is higher as the sectional area of the parallel flow path is smaller.