Abstract:
A metering solenoid valve is provided for refrigeration applications, wherein the metering solenoid valve combines the function and characteristics of a solenoid valve and a hand expansion valve into a single valve. The valve includes an adjustable stem housing allowing the flow of the valve to be adjusted.

Description:
CROSS-REFERENCE TO RELATED CASES 
       [0001]    This application claims the benefit of U.S. Provisional Application Ser. No. 61/054,497; filed May 20, 2008, the disclosure of which is expressly incorporated herein by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates, in general, to a metering solenoid valve such as the type used in refrigeration applications, and in particular to a valve that combines a solenoid valve and hand expansion valve into a single valve. 
       BACKGROUND 
       [0003]    A prior art heavy duty solenoid valve  110  is shown in  FIG. 1  as a pilot operated, semi-steel bodied valve suitable for Ammonia, R-12, R-22, and R-502, other refrigerants, certain oils and other fluids approved for use in refrigeration. The valve may be opened by means of the manual opening stem  112  for servicing or in case of electrical power failure (shown covered by cap  113 ). The valve is a pilot operated solenoid shown in  FIG. 1  in its closed position, with the solenoid coil  114  de-energized and the plunger needle  116  and main port plug  118  in the seated position. Electrical energization of the solenoid coil  114  forms a magnetic field, pulling up the plunger which strikes the needle  116 , lifting it off its seat  117 . Upward motion of the needle  116  permits entrance of the fluid from the valve inlet  120  through the pilot port  124  to the top of the power piston  126 . This forces the piston  126  downward and pushes the main port plug  118  open, thereby permitting flow of the refrigerant through the main valve port  188  to the outlet  121 . The closing spring meanwhile is held in a compressed position. De-energization of the solenoid coil  114  permits the spring-assisted needle  116  to drop back into its seat  117 , stopping the flow through the pilot port  124 . Bleed-off, through the bleed hole  128  in the piston  126 , decreases the pressure above the piston  126  and allows the closing spring  130  to force the main port plug  118  upward into a closed position to stop the flow. The pressure difference across the valve  110 , acting upon the area of the valve seat, plus the force of the closing spring  130 , holds the main port plug in a tightly closed position. 
         [0004]    The solenoid valves  110  typically require a hand expansion valve to be used in conjunction with the solenoid valve in order to meter the flow of the refrigerant. Referring to  FIG. 2 , a hand expansion valve  210  is shown having a tapered plug  218  for providing throttling action. 
       SUMMARY 
       [0005]    At least one embodiment of the invention provides a valve assembly comprising: a housing having a valve inlet and a valve outlet; a through port between an inlet fluid passageway and an outlet fluid passageway; a solenoid valve; a piston positioned between the outlet fluid passageway of the inlet and the solenoid valve; a by-pass port extending from the inlet to the solenoid valve; a plug biased against the port and movable between a closed position and a fully retracted position providing an annular opening through the port, a portion of the plug extending beyond the port and terminating at a distal end of the plug, the plug portion having an axial cross-section that gradually decreases toward a distal end of the plug; a manual opening stem engaging the plug and adapted to retract the plug from the port and provide an opening through the port. 
         [0006]    At least one embodiment of the invention provides a solenoid valve assembly comprising: a housing having a valve inlet and a valve outlet; a through port between an inlet fluid passageway and an outlet fluid passageway; a stem housing adjustably attached to the housing; a plug formed generally in a frustoconical shape biased against the port and movable to provide an annular opening through the port, the plug shape and position preventing full flow through the port; a manual opening stem engaging the plug and adapted to retract the plug from the port and provide an opening through the port. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    Embodiments of this invention will now be described in further detail with reference to the accompanying drawings, in which: 
           [0008]      FIG. 1  is a cross-sectional view of a prior art solenoid valve; 
           [0009]      FIG. 2  is a cross-sectional view of a prior art hand expansion valve; 
           [0010]      FIG. 3  is a perspective, cross-sectional view of an embodiment of the metering solenoid valve in accordance with the present invention; 
           [0011]      FIG. 4  is a cross-sectional view of an embodiment of the metering solenoid valve in accordance with the present invention in a closed position; and 
           [0012]      FIG. 5  is a cross-sectional view of an embodiment of the metering solenoid valve in accordance with the present invention in an open position. 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    An embodiment of the present invention is shown in  FIG. 3  as a metering solenoid valve assembly  10  in a perspective cross-sectional view and for additional clarity, in  FIG. 4  as a cross-sectional view in a closed position and in  FIG. 5  as a cross-sectional view in an open position. The valve assembly  10  comprises a housing  20  having an inlet  22 , an outlet  24 , an inlet passageway  26 , an outlet passageway  28  and a through port  30  providing a fluid passageway between the inlet passageway  26  and the outlet passageway  28 . As with the prior art solenoid valve, the inlet passageway  26  includes a by-pass port  32  which extends to a solenoid  34  which when energized allows fluid to flow to a chamber  36  above a piston  40 . The valve assembly  10  also includes a metering/manual open plug assembly  50  comprising a plug  52 , a closing spring  54 , a manual opening stem  56 , and an adjustable stem housing  58 . The metering/manual open plug assembly  50  combines the functionality of the manual open plug of the solenoid valve and the metering function of the hand expansion valve. In operation, the fluid entering chamber  36  forces piston  40  into the housing  20 . The piston engages the plug  52  which moves against the force of the closing spring  54  and opens the through port  30 . The plug  52  is limited in the distance that it is able to move. The end of the plug  52  engages a stop surface of the stem housing  58 . The stem housing  58  is adjustably positioned by threadably setting the depth of the step housing  58  into housing  20 , allowing the amount of flow through the port  30  to be adjusted due to the geometrical shape of the plug  52 . It is noted that the plug  52  shown is tapered in a generally frustoconical shape that extends a distance through the port  30  such that even when the port  30  is open, the plug  52  does not allow full flow through the port  30  and that an annular opening is formed. It is contemplated that other plug shapes could also be used that have a changing cross-sectional dimension along its axial length. 
         [0014]    The valve  10  may be opened by means of the manual opening stem  56  for servicing or in case of electrical power failure. The manual opening stem  56  has a head portion  57  which is coupled to the plug  52 . The stem  56  is threadably engaged by the stem housing  58  such that the valve  10  can be opened by rotating the stem  56 . The stem  56  retracts the plug  52  against the spring force to open the port  30   
         [0015]    The combination of the solenoid valve and the metering valve into a single valve can save in manufacturing costs, inventories, additional welds for two components, etc. 
         [0016]    Although the principles, embodiments and operation of the present invention have been described in detail herein, this is not to be construed as being limited to the particular illustrative forms disclosed. They will thus become apparent to those skilled in the art that various modifications of the embodiments herein can be made without departing from the spirit or scope of the invention.