Flow-regulating expansion valve

Abstract

To provide a small-sized solenoid-driven flow-regulating expansion valve which can be realized at low cost. In a flow-regulating expansion valve according to the present invention, a pipe forming a body thereof not only accommodates internal structures, such as a flow-regulating mechanism, a movable core, and a fixed core, but also serves as a part of piping of a refrigeration cycle. Further, a solenoid section including a solenoid coil is disposed outside the pipe in a manner surrounding the same. Therefore, substantial integration of the flow-regulating mechanism in the piping of the refrigeration cycle can be achieved, which makes the entire flow-regulating expansion valve very simple in construction. As a result, reduction of the size of the flow-regulating expansion valve and resultant reduction of material costs and manufacturing costs can be achieved, which makes it possible to achieve low costs of the flow-regulating expansion valve.

1 . A flow-regulating expansion valve provided in a flow passage of refrigerant circulating through a refrigeration cycle, for decompressing refrigerant flowing in from an upstream side thereof by adiabatically expanding the refrigerant, and delivering the refrigerant at a constant flow rate set by a value of an electric current supplied to a solenoid coil, the flow-regulating expansion valve comprising: 
 a pipe forming a part of the refrigerant flow passage;    a fixed core in the form of a hollow cylinder fixed in the pipe;    a movable core in the form of a hollow cylinder disposed in the pipe in a manner opposed to the fixed core in an axial direction such that the movable core is movable in the axial direction;    the solenoid coil circumferentially disposed outside the pipe in a manner surrounding the pipe, for generating a magnetic circuit including the movable core and the fixed core by an electric current which is externally supplied, to generate a solenoid force a magnitude of which corresponds to a value of the supplied electric current to thereby move the movable core to a predetermined reference position with respect to the fixed core; and    a flow-regulating mechanism provided in the pipe, for performing valve-opening or valve-closing operation while moving the movable core to and from the predetermined reference position to adjust an internal passage cross-section, and delivering the refrigerant downstream at the constant flow rate.    
   
   
       2 . The flow-regulating expansion valve according to  claim 1 , wherein the flow-regulating mechanism comprises: 
 a restriction formed by a fixed passage having a predetermined passage cross-section;    a valve seat provided in the pipe; and    a valve element formed such that the valve element can be removably seated on the valve seat by motion of the movable core, the valve element allowing the refrigerant to flow downstream through a gap between the valve element and the valve seat when the valve element is open, and    wherein a passage cross-section formed between the valve element and the valve seat is adjusted by the motion of the movable core such that a differential pressure across the restriction is held constant, whereby the flow rate of the refrigerant flowing downstream is held constant.    
   
   
       3 . The flow-regulating expansion valve according to  claim 2 , comprising a hollow member having one end-side part thereof fixedly fitted in the movable core and an opposite end-side part thereof slidably inserted in the fixed core, a part of the opposite end-side part being reduced in inner diameter to form the restriction, and a plurality of support portions formed at circumferentially spaced intervals in a manner extending from an extreme end of the opposite end-side part, and 
 wherein the valve seat is formed on an end of the fixed core opposite from the movable core, and    wherein the valve element has a guide portion in the form of a hollow cylinder guided by a hollow shaft in the form of a bottomed hollow cylinder provided on a side of the fixed core opposite from the movable core, and a valve portion configured such that the valve portion can be seated on the valve seat, the valve portion being formed with a communication hole for communicating between an inside of the guide portion and an inside of the hollow shaft, the valve element being urged toward the fixed core by a elastic member provided within the hollow shaft, and    wherein energization of the solenoid coil causes the hollow member to urge the valve element via the support portions to thereby move the valve element away from the valve seat such that the passage cross-section is formed between the valve element and the valve seat.    
   
   
       4 . The flow-regulating expansion valve according to  claim 2 , comprising a solid shaft in the form of a stepped column, the solid shaft having the movable core fitted on one end-side part thereof formed with a stepped portion to guide the movable core in directions of motion thereof, an opposite-end side part of the solid shaft being fixed in the pipe, and 
 a sealing member mounted on an end face of the movable core opposite from the fixed core and a one end-side end face of the solid shaft in a manner hermetically covering the end faces, and    wherein the valve seat is formed on a movable core-side end of the fixed core, and    wherein the movable core has a body in the form of a hollow cylinder having a valve portion of the valve element formed at an extreme end thereof such that the valve portion can be seated on the valve seat, and a non-magnetic member in the form of a hollow cylinder formed in a manner continuous with the body and extending therefrom into the fixed core, the non-magnetic member being circumferentially formed with a flange for forming the restriction between an inner wall of the fixed core and the flange, and forms a predetermined inner space between the stepped portion of the solid shaft and the movable core itself.    
   
   
       5 . The flow-regulating expansion valve according to  claim 2 , comprising a solid shaft in the form of a stepped column, the solid shaft having the movable core fitted on one end-side part thereof formed with a stepped portion to guide the movable core in directions of motion thereof, an opposite-end side part of the solid shaft being fixed in the pipe, and 
 wherein the valve seat is formed on a movable core-side end of the fixed core, and    wherein the movable core has a body in the form of a hollow cylinder having a valve portion of the valve element formed at an extreme end thereof such that the valve portion can be seated on the valve seat, and a non-magnetic member in the form of a hollow cylinder formed in a manner continuous with the body and extending therefrom into the fixed core, the non-magnetic member being circumferentially formed with a flange for forming the restriction between an inner wall of the fixed core and the flange, and forms a predetermined inner space between the stepped portion of the solid shaft and the movable core itself, and    wherein sliding surfaces of the solid shaft and the movable core, which communicate with the inner space, on a side opposite from the fixed core, are configured to have a length not shorter than a predetermined length such that leakage of the refrigerant via the sliding surfaces can be suppressed.    
   
   
       6 . The flow-regulating expansion valve according to  claim 2 , comprising a solid shaft in the form of a column, the solid shaft having the movable core fitted on one end-side part thereof to guide the movable core in directions of motion thereof, an opposite-end side part of the solid shaft being fixed in the pipe, and 
 wherein the movable core has a body in the form of a hollow cylinder having a valve portion of the valve element formed at an extreme end thereof such that the valve portion can be seated on the valve seat, and forming a predetermined clearance passage axially extending between the pipe and the movable core itself, and a flow-reducing portion formed continuous with the valve portion, and having a flange formed thereon in a protruding manner to form the restriction between an inner wall of the pipe or a hollow cylindrical member fitted in the pipe, the movable core further forming, between the solid shaft and the movable core itself, a predetermined inner space for communicating with the refrigerant flow passage.    
   
   
       7 . The flow-regulating expansion valve according to  claim 6 , wherein the fixed core, the movable core, and the hollow cylindrical member having the valve seat fixed in the pipe are arranged in the mentioned order from an upstream side of the refrigerant flow passage, and 
 wherein an upstream end of the solid shaft extends through the fixed core while maintaining a refrigerant passage, with an extreme upstream end of the solid shaft fixed on an upstream end of the fixed core, and    wherein an elastic member is interposed between a downstream end of the solid shaft and an inner wall of the movable core, for connecting between the solid shaft and the movable core to support the movable core.    
   
   
       8 . The flow-regulating expansion valve according to  claim 2 , comprising a solid shaft in the form of a column, the solid shaft having the movable core fitted on one end-side part thereof to guide the movable core in directions of motion thereof, an opposite-end side part of the solid shaft being fixed in the pipe, and 
 wherein the fixed core has the valve seat formed on a movable core-side end thereof, with a flange formed thereon in a manner protruding inward at a predetermined axial location, and    wherein the movable core comprises:    a body in the form of a hollow cylinder having a valve portion of the valve element formed at an extreme end thereof such that the valve portion can be seated on the valve seat, and forming a predetermined clearance passage axially extending between the pipe and the movable core itself, the movable core further forming, between the solid shaft and the movable core itself, a predetermined inner space for communicating with the refrigerant flow passage; and    a pressure-equalizing pipe fitted in the body in a manner extending into the fixed core and communicating with the inner space, and    wherein the restriction is formed between an end of the pressure-equalizing pipe and the flange part.    
   
   
       9 . The flow-regulating expansion valve according to  claim 2 , comprising a solid shaft in the form of a column, the solid shaft having the movable core fitted on one end-side part thereof to guide the movable core in directions of motion thereof, an opposite-end side part of the solid shaft being fixed in the pipe, and 
 wherein the fixed core has the valve seat formed on a movable core-side end thereof, and further the fixed core has a flange formed thereon in a manner protruding inward at a predetermined axial location, and a passage pipe extending into the movable core, and    wherein the movable core has a body in the form of a hollow cylinder having a valve portion of the valve element formed at an extreme end thereof such that the valve portion can be seated on the valve seat, and forming a predetermined clearance passage axially extending between the pipe and the movable core itself, the movable core further forming, between the solid shaft and the movable core itself, a predetermined inner space for communicating with the refrigerant flow passage, and    wherein the restriction is formed between the passage pipe and the movable core.    
   
   
       10 . The flow-regulating expansion valve according to  claim 2 , comprising a solid shaft in the form of a stepped column, the solid shaft having the movable core fitted on one end-side part thereof formed with a stepped portion to guide the movable core in directions of motion thereof, an opposite-end side part of the solid shaft being fixed in the fixed core, and 
 a sealing member mounted on an end face of the movable core opposite from the fixed core and a one end-side end face of the solid shaft in a manner hermetically covering the end faces, and    wherein the valve seat is formed on a movable core-side end of the fixed core, and    wherein the movable core has a body in the form of a hollow cylinder having a valve portion of the valve element formed at an extreme end thereof such that the valve portion can be seated on the valve seat, and forms a predetermined inner space between the solid shaft and the movable core itself, and a predetermined clearance axially extending between the pipe and the movable core itself, the restriction being formed by the clearance.    
   
   
       11 . The flow-regulating expansion valve according to  claim 2 , wherein the valve seat is formed on a movable core-side end of the fixed core, and 
 wherein the movable core has a body in the form of a hollow cylinder having a valve portion of the valve element formed at an extreme end thereof such that the valve portion can be seated on the valve seat, with a portion thereof in the vicinity of the valve portion being reduced in inner diameter to form the restriction, and a large-bore part thereof formed on a side of the restriction opposite from the fixed core being fitted on a hollow cylindrical member rigidly fitted in the pipe, such that the movable core is guided by the hollow cylindrical member.