Patent Publication Number: US-6334320-B1

Title: Electronic manifold for a refrigerant servicing unit

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority under 35 U.S.C. §1.119(e) on U.S. Provisional Application No. 60/126,961 entitled ELECTRONIC MANIFOLD FOR A REFRIGERANT SERVICING UNIT, filed on Mar. 30, 1999, by William C. Brown and James P. Biedenharn, the entire disclosure of which is incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to an electronic refrigeration servicing unit and particularly to an improved manifold for coupling the unit to a refrigeration circuit. 
     Typically, when servicing refrigeration circuits, it is necessary to use manifold gauges which are coupled to the refrigeration circuit utilizing hoses for the high and low pressure sides of the system. The hoses typically are five to six feet in length and, therefore, have a significant interior volume. Small refrigerant systems, such as ice makers and the like, utilize a relatively small amount of refrigerant and the coupling of hoses leading to servicing gauges itself causes a loss of refrigerant from the system which can be sufficient to require recharging. Thus, when testing a refrigerant circuit, it is possible that the testing procedure itself adversely affects a system which may otherwise have been fully charged by leaking refrigerant into the hoses such that recharging becomes necessary. Also, with relatively long hoses, refrigerant is lost to the atmosphere during servicing, which is undesirable in view of environmental concerns. Such hoses, when used with the variety of different refrigerants now in common use, can also cause cross contamination of refrigerants and their associated lubricants. 
     SUMMARY OF THE INVENTION 
     The system of the present invention eliminates the need for lengthy hoses by providing a manifold having an electrical pressure transducer which is coupled to electrical displays, thereby eliminating the need for conventional pressure gauges with hoses attached to the refrigeration circuit. In a preferred embodiment of the invention, a pressure transducer is incorporated in a manifold with one end which threads directly onto the refrigeration unit. The manifold also has a coupling which allows attachment of a servicing hose for recharging the refrigeration unit, if necessary. 
     Thus, with the system of the present invention, the pressure of a refrigeration circuit can be monitored without any significant refrigerant loss and, if further servicing is necessary, allows the coupling of a vacuum pump and a refrigerant source directly to the refrigerant circuit and continuous monitoring of the system during servicing. As a result, the risk of cross-mixing refrigerants is eliminated which could occur with conventional hoses employed for servicing different units having different refrigerants. Loss of refrigerant when servicing small units is minimized. Also, there is little or no venting of refrigerant from hoses to the environment. The electrical leads from the transducers to the hand-held electronic diagnostic unit are flexible and lightweight and, therefore, easy to handle, store and maneuver in tight places encountered in servicing refrigeration units. 
     These and other features, objects and advantages of the present invention will become apparent upon reading the following description thereof together with reference to the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front elevational view of a servicing unit embodying the present invention; 
     FIG. 2 is a perspective view of the servicing unit shown in FIG. 1; 
     FIG. 3 is a partly exploded perspective view of a manifold and electrical connection from the pressure transducer contained therein to the service unit shown in FIGS. 1 and 2; 
     FIG. 4 is a perspective view of the manifold shown in FIG. 3, shown coupled to a refrigeration circuit for monitoring the pressure of the system; and 
     FIG. 5 is a perspective view of the manifold shown in FIGS. 3-4, shown with a servicing hose coupled thereto for adding refrigerant or for evacuating the system. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring initially to FIGS. 1 and 2, there is shown the hand-held electronic diagnostic unit  10  of the present invention including a housing  12 , which can be held in a person&#39;s hand  13 . Housing  12  includes a wire hanger  14  for alternatively hooking the instrument at a convenient location during servicing of a refrigeration circuit. The unit  10  includes a display panel  16  for the low pressure side and a display panel  18  for the high pressure side, as well as control switches  19 - 22  for controlling the power for the unit, the mode of operation, the stored pressure information, and resetting the pressure displays. Housing  12  also includes a socket for receiving one of several refrigerant identification keys  24 , each of which includes a ROM memory with a table programmed for pressure and temperatures for a given refrigerant. The memory is coupled to a microprocessor contained within the servicing unit  10  to calibrate the instrument for a particular type of refrigerant. 
     In addition, the housing  12  includes a first socket  30  for receiving a plug  32  coupled to an electrical conductor  34  leading to a pressure transducer or sensor  36  (FIG.  3 ), as described in greater detail below. The housing also includes a second socket  31  for receiving plug  33  coupled to conductor  35  also coupled to another pressure sensor for the high pressure side of the refrigeration circuit being serviced. Finally, housing  12  includes an additional socket  37  for receiving a plug  38  coupled to a conductor  39  leading to a temperature probe which can be attached to the refrigeration circuit for reading ambient, suction line, shell, evaporator, or condenser temperatures during a servicing cycle. 
     The housing  12  is relatively compact, as seen in FIG. 1, and can be hand-held or hooked utilizing the wire hanger  14  to the refrigeration unit being serviced. The display contained within the housing  10 , the microprocessor and its programming forms no part of the present invention other than to utilize the electrical signals from the unique manifolds  50  (FIGS. 3-5) employed for low side and high side pressure sensing, as now described in connection with FIGS. 3-5. 
     Referring to FIG. 3, there is shown a generally T-shaped manifold  50  which includes a body  52  having a conventional electrically actuated pressure transducer  36  threaded into the center thereof and communicating with the interior space  51  of the manifold  50 . One end of the manifold  50  includes a female threaded coupling  54  for attachment of the manifold to a nipple on the refrigerant circuit being serviced, as illustrated in FIG.  4 . Coupling  54  is conventionally rotatably mounted to the manifold utilizing a suitable seal and gasket to allow its knurled outer surface to be rotated for attaching the manifold  50  in sealing engagement with the refrigeration unit. The end of manifold  50  opposite coupling  54  includes a male threaded quarter-inch flare-type coupling  56  internally including a Schraeder valve near such coupling for sealing the coupling  56  until such time as refrigerant is to be passed through the coupling. A sealed end cap  58  is tethered to the coupling  56  by means of a strap  59 . 
     In use, a pair of the manifolds  50  integrally including pressure transducers  36  are attached to the high and low side of the refrigerant circuit  60  (one transducer is shown in FIG. 4) utilizing the threaded coupling  54 . The electrical conductor  34  for each of the pressure transducers is then extended from the refrigerant circuit and plugged into the sockets  30  and  31  of the servicing unit  10  as illustrated in FIG. 1 for receiving operating power and providing pressure representative signals to unit  10 . For servicing requiring temperature measurements, the temperature probe is also plugged into the unit  10  utilizing plug  38  and socket  37 . The servicing unit is then operated in a normal fashion through the sequence of pressure and temperature measurements to determine whether additional refrigerant is required or the system needs to be otherwise serviced. 
     If additional refrigerant is required, on either the high end or the low end of the system, as illustrated in FIG. 5, the protective cap  58  is removed from the manifold  50  and a service hose  70  is attached to the coupling  56  utilizing a standard threaded coupling  72 . Hose  70  is coupled to a supply hose  74  through a valve  76 . The valve is actuated while the service personnel monitors the pressure until a desired amount of refrigerant has been added to either the high side or the low side. As can be seen with the system of the present invention, only the T-shaped manifolds  50  are attached to the refrigeration circuit for purposes of monitoring the pressures, thus eliminating the hoses typically associated with servicing units and the accompanying loss of refrigerant, cross contamination and other problems associated with servicing hoses. The remote commercially available pressure sensors are integrally installed in the manifolds  50  such that a convenient coupling is also provided for the addition of refrigerant, as illustrated in FIG. 5, or for the evacuation of the refrigeration circuit utilizing a vacuum pump. Such a system, therefore, greatly simplifies the servicing of a refrigeration circuit and, particularly where small charges of refrigerant are employed, prevents unnecessary escape and loss of refrigerant. 
     It will become apparent to those skilled in the art that various modifications to the preferred embodiment of the invention can be made without departing from the spirit or scope of the invention as defined by the appended claims.