Abstract:
A pressure responsive oil flow regulating supply valve assembly includes an oil supply input; an oil supply output; an oil flow path defined between the input and output. A valving mechanism located in the oil flow path includes a device for restricting oil flow at a first level in response to normal pressure and for restricting oil flow at a second level in response to high pressure conditions. In addition, other levels of restriction may be provided for other pressure conditions.

Description:
TECHNICAL FIELD  
         [0001]    This invention is directed to oil flow control and more particularly to an oil-flow regulating supply valve for a compressor which is responsive to changes in pressure for changing oil flow volume to the compressor.  
         BACKGROUND ART  
         [0002]    In compressors, oil is often supplied for lubrication from a pressurized oil sump. Since the oil is pressure-fed an oil pump is typically not used in a compressor system but oil flow is usually regulated by internal oil metering orifices. In low pressure situations, such as at ambient temperature start up where refrigerant pressures are low, the compressor may operate for a period of time without enough pressure differential to allow the supply of oil at an adequate level. Conventionally, an auxiliary oil pump is used to make up the pressure shortage or a variable restriction is provided on the vapor line downstream of the oil separator and sump to induce a pressure differential. Both solutions can be costly and the provision of a variable restriction can cause an undesirable performance penalty.  
           [0003]    Also, during normal operation, it may be desirable to regulate oil flow at extreme operating conditions in a manner other than that provided by internal oil metering orifices.  
           [0004]    Therefore, a solution is necessary to provide the benefits of an auxiliary pump or vapor line restriction while eliminating the cost and potential performance penalty. It is also desired to provide a more complex, or programmed, regulation of oil flow than that provided by a simple orifice.  
         DISCLOSURE OF INVENTION  
         [0005]    The primary object of this invention is to provide an improved pressure responsive oil flow regulating supply valve for a compressor.  
           [0006]    Another object of the present invention is to provide a pressure responsive oil flow regulating supply valve adaptive to multiple pressure situations.  
           [0007]    Still another object of the present invention is to provide a pressure responsive oil flow regulating supply valve having a translating spool with varying diameter sections moveable into the oil flow path for regulating oil in response to pressure changes.  
           [0008]    And still another object of the present invention is to provide a pressure responsive oil flow regulating supply valve having a translating plunger for exposing one or multiple orifices to oil flow for regulating oil in response to pressure changes.  
           [0009]    The foregoing objects and following advantages are achieved by the pressure responsive oil flow regulating supply valve of the present invention which includes an oil supply input; an oil supply output; an oil flow path defined between the input and output; and a valving mechanism located in the oil flow path, the valving mechanism including means for restricting oil flow at predetermined different levels in response to differing pressure conditions.  
           [0010]    In one preferred embodiment, the means for restricting preferably comprises a biased spool with multiple portions of differing diameter. Each of the multiple portions has a diameter for restricting flow at one of the predetermined levels in response to varying pressure conditions.  
           [0011]    Alternatively, and in another preferred embodiment, the means for restricting comprises a plunger and bore assembly. The plunger translates in the bore formed in the valve assembly housing and the assembly further includes a master orifice and a secondary orifice. The secondary orifice is closed during high pressure for restricted flow and the secondary and master orifices are open during low pressure for increased flow. Additional orifices may also be added to provide additional increments of flow restriction at various pressures.  
           [0012]    In another embodiment, the means for restricting further includes means for restricting flow in response to extreme conditions at a first intermediate level between the high level and the low level restrictions. 
       
    
    
     BRIEF DESCRIPTIONS OF THE DRAWINGS  
       [0013]    [0013]FIG. 1 is a plan view of the first embodiment of the oil flow regulating valve assembly of present invention, shown in the normal pressure and normal oil flow rate state.  
         [0014]    [0014]FIG. 2 is a plan view of the valve assembly shown in FIG. 1, in the high pressure, high oil flow rate state.  
         [0015]    [0015]FIG. 3 is a plan view of the valve shown in FIG. 1, in the extreme high pressure, mid-level oil flow rate state.  
         [0016]    [0016]FIG. 4 is a plan view of the valve shown in FIG. 1, in the extreme low pressure, mid-level oil flow rate state.  
         [0017]    [0017]FIG. 5 is a plan view of the second embodiment of the valve of the present invention, shown in the normal pressure and normal oil flow rate state.  
         [0018]    [0018]FIG. 6 is a plan view of the valve shown in FIG. 5, in the low pressure, high oil flow rate state. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0019]    Referring now to the drawings in detail, there is shown in FIG. 1 a pressure regulating oil supply valve assembly for use in an air conditioning or refrigeration compressor such as a twin screw compressor, which is designated generally as  10 .  
         [0020]    The valve assembly  10  generally includes housing  12 , oil supply inlet  14 , oil supply outlet  16 , and spindle  18 . Spindle  18  is slideably positioned in a bore  20  within housing  12  and is biased in bore  20  via spring  22 . As shown in FIG. 1, the valve assembly is located in the compressor between the oil supply from the separator and the oil supply to the compressor. Accordingly, the valve assembly, and specifically spindle  18  operate to variably restrict flow to the compressor in accordance with variable pressure conditions.  
         [0021]    Referring still to FIG. 1, spindle  18  includes multiple diameter portions  24 ,  26 ,  28 , and  30 . As shown in FIG. 1, spindle  18  is positioned in bore  20  such that diameter portion  26  is positioned in the oil flow path between the oil supply from the separator to the oil supply to the compressor. The position shown in FIG. 1 is a first level normal pressure position, whereby diameter portion  26  having the largest diameter portion of spindle  18 , is positioned in the oil flow path. Accordingly, in normal pressure conditions, spindle  18  operates to regulate flow to the lowest flow rate condition.  
         [0022]    Referring to FIG. 2, spindle  18  is shown in the high pressure position, whereby diameter portion  28  is positioned in the oil flow path such that at high pressure, a second level minimal flow restriction is provided by spool or spindle  18 . As shown in FIG. 3, Spindle  18  has shifted all the way to the left, indicative of an extreme high pressure situation such that oil flow is again restricted, but by diameter portion  30  of Spindle  18  at a third intermediate level between the normal pressure and high pressure spindle restrictions.  
         [0023]    Finally, as shown in FIG. 4, at extreme low pressure conditions diameter portion  24  is positioned in the oil flow path substantially restricting oil flow, to a fourth level, substantially the same level of restriction provided by diameter portion  30  for the extreme pressure conditions.  
         [0024]    In operation, and referring to FIGS.  1 - 4 , spindle  18  is positioned in bore  20  of valve assembly  10  and as shown in FIG. 4, under low pressure start up conditions diameter portion  24  resides in the oil path substantially reducing oil flow. This position would also apply in the case that discharge pressure is lost within the compressor. As indicated in FIG. 1, as a pressure differential builds to normal levels within the compressor, Spindle  18  shifts within bore  20  over the bias of spring  22  such that diameter portion  26  moves into the oil flow path and under these normal conditions, the oil flow is substantially restricted at a maximum level for spindle  18 , as made possible by the large diameter portion  26 . As indicated in FIG. 2, as pressure differential further increases, under high pressure conditions, spindle  18  shifts to the left against the bias of spring  22  such that diameter portion  28  moves into the flow path of the oil flowing through the valve assembly  10 . As shown by the figures, diameter portion  28  is the smallest diameter portion of spindle  18  and accordingly, under high pressure, high volume oil flow is allowed by spindle  18 . As shown in FIG. 3, during operation, if an extremely high pressure situation arises, spindle  18  shifts all the way to the left in bore  20  against the bias of spring  22  thereby placing diameter portion  30  in the flow path of the oil flowing from the separator to the compressor. Accordingly, oil flow is restricted at a greater level than as provided by the high pressure position, due to diameter portion  30 .  
         [0025]    Referring now to FIG. 5, a second embodiment of the pressure regulating oil supply valve assembly is shown, fixed to the end of a screw rotor housing defining an oil path between the oil separator and the screw rotor housing. Valve assembly  110  generally includes a housing  112 , a translating plunger  114 , a biasing spring  116 , a master orifice  118 , and a secondary orifice  120 .  
         [0026]    Housing  112  is preferably cylindrical in shape, with plunger  114  residing and translating in a bore  122  therein. As shown, bore  122  includes a large portion  124  and a smaller portion  126 , wherein spool  114  resides and translates in large portion  124  and spring  116  resides in small portion  126 , biasing plunger  114  toward the oil inlet  128 . Master orifice  118  extends through the closed end  130  of plunger  114 , allowing flow of oil through spring  116  and out second stage orifice  132  in housing  112 , which functions to throttle the oil flow to predetermined flow rates. Secondary orifice  120  extends substantially perpendicularly to master orifice  118  and resides in housing  112  spaced from exit orifice  132  toward oil inlet  128 . In the high pressure position as shown in FIG. 5, secondary orifice  132  is blocked for flow therethrough via the outer wall  134  of plunger  114 . In low pressure situations as shown in FIG. 6, spring  116  forces plunger  114  toward the oil inlet  128 , exposing secondary orifice  120 .  
         [0027]    In operation, and referring to FIGS. 5 and 6, valve assembly  110  is positioned on the screw housing and as shown in FIG. 6 under low pressure or start up conditions both the master and secondary orifices are exposed for high volume oil flow. This position would also apply in the case that discharge pressure is lost within the compressor and a low pressure condition exists, or at start up. As indicated in FIG. 5, as a pressure differential builds within the compressor, plunger  114  translates within large bore portion  124  over the bias of spring  116  such that outer wall  134  of plunger  114  moves over secondary orifice  120 , blocking the oil path thereto and allowing oil flow only through the master orifice. Additional orifices could be provided for the purpose of more particularly adjusting oil flow, such that as pressure builds a plurality of orifices are sequentially closed or such that as pressure lessons, a plurality of orifices are sequentially opened. Such additional orifices could be located in housing  120 , substantially parallel to secondary orifice  112 .  
         [0028]    The primary advantage of this invention is that an improved pressure responsive oil flow regulating supply valve is provided for a compressor.  
         [0029]    Another advantage of the present invention is that a pressure responsive oil flow regulating supply valve is provided, which is adaptive to multiple pressure situations.  
         [0030]    Still another advantage of the present invention is that a pressure responsive oil flow regulating supply valve having a translating spool with varying diameter sections is provided for regulating oil in response to pressure changes.  
         [0031]    And still another advantage of the present invention is that a pressure responsive oil flow regulating supply valve is provided, having a translating plunger for exposing one or multiple orifices to oil flow for regulating oil in response to pressure changes.  
         [0032]    Although the invention has been shown and described with respect to the best mode embodiment thereof, it should be understood by those skilled in the art that the foregoing and various other changes, omissions, and additions in the form and detail thereof may be made without departing from the spirit and scope of the invention.