Abstract:
A shut-off valve for pressurized fluids in an air cooling/heating apparatus that includes at least one condenser and at least one fluid evaporator communicating with each other by a pipe. The valve includes two ducts each containing a restrictor coaxially formed with a capillary designed to cause rapid expansion of the fluid when it emerges from the capillary, thus allowing expansion of the fluid in either the heating or cooling mode. The valve further includes a duct for sampling the pressurized fluid before expansion during operation in either the heating or cooling mode.

Description:
RELATED CASES 
     The present application claims priority to European Patent Application Serial No. 00830714.2-2301; filed Oct. 30, 2000. 
     1. Field of the Invention 
     The present invention relates to a shut-off valve for pressurized fluids in an air cooling/heating system such as air conditioners and the like. 
     2. Background of the Invention 
     It is known in the art of air conditioners and heat pumps that a condenser and an evaporator must be placed in communication with each other by means of shut-off valves and other devices designed to cause expansion of the refrigerant as the refrigerant flows from one component to another. 
     Specifically, in refrigerant systems operating in both the cooling and heating modes, two expansion devices may be incorporated into one system allowing for expansion of the fluid in either direction. A shut-off valve may also be incorporated into a system when there is a need to terminate refrigerant flow, such as for example, during servicing. The refrigerant system may also include a sampling port for detecting and measuring the pressure of the high-pressure refrigerant before the refrigerant enters the expansion device. Furthermore, the ability to easily interchange the expansion device allows the degree of expansion to be selectively varied after installation of the shut-off valve. 
     Combining the shut-off valve, expansion devices and sampling device into one unit is desirable to reduce the complexity of a refrigerant system. However, known refrigerant systems lack a mechanism for sampling the liquid refrigerant before the liquid enters the expansion devices in both the cooling and heating modes. Therefore, a need exists for a shutoff valve that allows for sampling high-pressure liquid between two expansion devices. 
     SUMMARY OF THE INVENTION 
     The present invention resolves the above noted problem by providing a mechanism that permits sampling of fluid refrigerant before expansion in either the cooling or heating mode. In particular, a shut-off valve is disclosed that includes at least two ducts. A first duct is positioned in communication with an evaporator. A second duct is positioned in communication with a condenser. Preferably, a third duct is adapted for receiving an instrument for sampling the fluid. A restrictor is arranged within the first and second ducts wherein each restrictor is formed with a capillary through which fluid passes and which causes rapid expansion of the fluid when the fluid exits from the capillary. Each restrictor is confined to an area defined by a cartridge and the body of the valve allowing limited axial movement of the restrictor in the direction of the fluid flow. 
     In accordance with the preferred embodiment, an insert member retains a cartridge in the first duct. The insert member is preferably retained by a flared nut threaded onto an externally threaded end of the first duct thereby clamping a flared end of a pipe directly against a conical surface of the insert member forming a seal. A cartridge in the second duct is preferably retained by a pipe received in a counterbore created between the second duct and the cartridge. The pipe is fixedly attached to the body of the valve by brazing or other suitable means of attachment. 
     In operation, the pressurized fluid flows from duct one to duct two in the heating mode and from duct two to duct one in the cooling mode. The valve is arranged such that duct three, or the duct receiving the sampling instrument, is positioned between ducts one and two. In this arrangement, the instrument may measure the pressure of the fluid as it flows between duct one and duct two. The shut-off valve arrangement is advantageous because it allows the fluid to be sampled before expansion in either the heating or cooling mode. 
     In accordance with a second embodiment, each cartridge is retained by a pipe received in a counterbore created between each cartridge and the corresponding duct. The pipe is fixedly attached to the body of the valve by brazing or other suitable means of attachment. A brazed pipe connection is advantageous because it requires fewer elements than a flared pipe connection. 
     In accordance with a third embodiment, an insert member retains each cartridge in both the first and second ducts. Each insert member is retained by a nut threaded onto an externally threaded end of each duct thereby clamping a flared end of a pipe directly against a conical surface of the insert member forming a seal. A flared pipe connection is advantageous because the connection can be disassembled allowing the substitution of a restrictor with a different capillary diameter. The ability to interchange a restrictor allows the shut-off valve to be field serviced without the need for complex brazing operations. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The features and inventive aspects of the present invention will become more apparent upon reading the following detailed description, claims, and drawings, of which the following is a brief description: 
     FIG. 1 is a partially sectioned view of a shut-off valve according to the present invention; 
     FIG. 2 is a partially sectioned exploded view of the shut-off valve; 
     FIG. 3 is a partially sectioned view of the shut-off valve operating in the heating mode; 
     FIG. 4 is a partially sectioned view of the shut-off valve operating in the cooling mode; 
     FIG. 5 is a cross sectional view along the plane indicated by  5 — 5  in FIG. 4.; 
     FIG. 6 is a partially sectioned view of a second embodiment of a shut-off valve having two brazed pipe connections; and 
     FIG. 7 is a partially sectioned view of a third embodiment of a shut-off valve having two flared pipe connections. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring to FIGS. 1 and 2, a preferred embodiment of a shut-off valve  10  in accordance with the principles of the current invention is shown. Shut-off valve  10  includes a body  12  that has formed therethrough, at least two ducts. A first duct  14  communicates with an evaporator (not illustrated). A second duct  16  communicates with a condenser (not illustrated). Preferably, valve body  12  includes a third duct  18  that is adapted to receive a sampling mechanism  20  for allowing the detection and measurement of the fluid pressure between ducts  14 ,  16  and  18 , to be explained in further detail below. Valve  10  further includes an obturator  22  that may be displaced by rotation between a closed position in which fluid flow between first duct  14  and second duct  16  is blocked (not shown) and an open position in which flow between first duct  14  and second duct  16  is permitted (shown as open in FIG.  1 ). 
     As seen in FIG. 2, first duct  14 , that is in communication with the evaporator, is formed inside a first outlet  24  of body  12  with an external thread  26  located on body  12 . Outlet  24  has positioned therein three coaxial seats  28 ,  30  and  32 . Coaxial seats  28 ,  30  and  32  receive and house a restrictor  34 , a cartridge  36  and an insert member  38  respectively. 
     The inside diameter of each coaxial seat  28 ,  30  and  32  is slightly larger than the outside diameter of restrictor  34 , cartridge  36  and insert member  38  respectively, such that restrictor  34 , cartridge  36  and insert member  38  are slidably assembled in their respective seats without interference. A filtering element  40 , having a screen portion  42  of suitable gauge, is fixedly attached to a distal end  43  of cartridge  36  and is designed to trap contaminants in order to prevent blockage in the system. Preferably, filtering element  40  is retained within a forward chamber  44  of cartridge  36  by press fit engagement. However, other suitable attachment mechanisms may be employed. 
     Restrictor  34  is formed with an axial capillary duct  46  with a predetermined diameter that corresponds to the desired degree of expansion of the fluid. Restrictor  34  is provided with a plurality of radial fins  47  that terminate in a projection  48 . Radial fins  47  cooperate with both an interior surface  50  of cartridge  36  and seat  28  to create a plurality of flow channels  52  (best seen in FIG. 5) for the free flow of fluid. A void  54 , (best seen in FIG. 1) defined between an interior angled sealing surface  56  of cartridge  36  and a shoulder  58  of seat  28 , allows for a limited degree of axial movement of restrictor  34 . Projection  48  is designed to cooperate with shoulder  58  of seat  28  in order to limit axial movement of restrictor  44  in a direction towards obturator  22 . Similarly, internally angled sealing surface  56  of cartridge  36  is designed to cooperate with a sealing end  60  of restrictor  34  to limit axial movement of restrictor  34  in a direction toward a connecting pipe  62 . 
     Insert member  38  has an end portion  64  received within outlet  24  so as to engage an upper angled portion  66  of cartridge  36  and retain cartridge  36  in seat  30 . A cylindrical portion  68  of insert member  38  engages seat  32  in outlet  24  so as to provide a seal to prevent the passage of fluid. Preferably, cylindrical portion  68  of insert member  38  is also formed with an annular seat  70  housing an annular sealing element  72  such as an O-ring. Insert member  38  further includes a conical surface  73  designed to cooperate with a flared end  74  of connecting pipe  62  to ensure a seal. Insert member  38  is preferably retained in seat  32  by a nut  76  that can be tightened on external thread  26  of outlet  24 . An internal conical surface  78  of nut  76  acts against flared end  74  of connecting pipe  62  forming a seal between connecting pipe  62  and insert member  38 . 
     Second duct  16 , in communication with the condenser, is formed inside a second outlet  80  of body  12 . Outlet  80  has formed therein two coaxial seats  82  and  84 . Coaxial seats  82  and  84  receive and house a cartridge  36   a  and a restrictor  34   a  that are substantially identical to cartridge  36  and restrictor  34  in first duct  14 . Cartridge  36   a  is retained in seat  82  by a second connecting pipe  86  that is positioned in a counterbore  88  created between an upper angled portion  66   a  of cartridge  36   a  and seat  82 . Connecting pipe  86  is fixedly attached to valve body  12  preferably by brazing connecting pipe  86  to outlet  80 . However other suitable methods of attaching connecting pipe  86  and outlet  80  may also be employed. 
     As illustrated in FIG. 3, during operation in the heating mode, fluid flows through valve  10  from connecting pipe  62  to connecting pipe  86 , first passing through filtering element  40 . The pressure of the fluid itself produces axial movement of restrictor  34  away from cartridge  36  thus causing opening of flow channels  52 . In this configuration, the fluid from pipe  62  is able to flow freely around a sealing end  60  of restrictor  34  into first duct  14  through flow channels  52 . When obturator  22  is in the open position, fluid may freely flow from first duct  14  into second duct  16  whereby the fluid encounters restrictor  34   a.  The pressure of the fluid itself produces movement of restrictor  34   a  until a sealing end  60   a  of restrictor  34   a  makes contact with an internal angled sealing surface  56   a  of cartridge  36   a , thus effecting a seal. In this configuration, the fluid from second duct  16  is able to flow freely until it encounters restrictor  34   a  where, in order for it to pass through restrictor  34   a , the fluid is necessarily channeled into capillary  46   a  causing expansion of the fluid as the fluid exits capillary  46   a  at sealing end  60   a . The expanded fluid then exits valve  10  into pipe  86  through a filtering element  40   a.    
     Operation occurs in a substantially similar manner, but in the opposite direction, during operation of the valve in the cooling mode as illustrated in FIG.  4 . During operation in the cooling mode, fluid enters outlet  80  through pipe  86  whereby fluid pressure produces movement in restrictor  34   a  away from cartridge  36   a  causing an opening of flow channels  52   a . When obturator  22  is in the open position, fluid is then directed into duct  14  such that fluid pressure produces movement in restrictor  34  towards cartridge  36  to effect a seal between sealing end  60  of restrictor  34  and angled sealing surface  56  of cartridge  36 . In this configuration, the fluid is able to flow freely until it encounters restrictor  34  where it is channeled through capillary  46  causing expansion of the fluid as the fluid exits capillary  46  at sealing end  60 . 
     In operation, fluid flows through valve  10  from pipe  62  to pipe  86  in the heating mode and from pipe  86  to pipe  62  in the cooling mode. In the heating mode, fluid freely flows around restrictor  34  into duct  14 . When the obturator  22  is in the open position, the fluid is then free to flow into duct  16  and duct  18 . Once in duct  18 , the fluid pressure may be detected and measured via sampling mechanism  20  received in duct  18 . Operation occurs in a substantially similar manner, but in the opposite direction, during operation of the valve in the cooling mode. 
     FIG. 6 illustrates a variation of embodiment of valve  10  in which a brazed connection is used at both the first and second outlets. The valve operation and expansion process perform identically as described in the configurations illustrated in FIGS. 3 and 4. A brazed pipe connection is advantageous because it requires fewer assembly elements. 
     FIG. 7 illustrates a variation of the embodiment of valve  10  in which a flared connection is used at both the first and second outlets. The valve operation and expansion process perform identically as described in the configurations illustrated in FIGS. 3 and 4. A flared connection is advantageous because the connection can be easily disassembled allowing the substitution of restrictors. The ability to interchange a restrictor allows the shutoff valve to be field serviced without the need for complex brazing operations. Furthermore, restrictors with different capillary diameters may be employed such that the degrees of expansion may be selectively varied. 
     Preferred embodiments of the present invention have been disclosed. A person of ordinary skill in the art would realize, however, that certain modifications would come within the teachings of this invention. Therefore, the following claims should be studied to determine the true scope and content of the invention.