Abstract:
An air compressor system having an air/oil separator for use with an air compressor, the air/oil separator including a separator tank having a side wall with an air exit port; a separator element hold down mechanism between the separator element and a lid mounted on the separator tank; and a separator element oil scavenge device which scavenges oil from the bottom of the separator element and passes the scavenged oil through the side wall of the separator tank. A method of replacing a separation element in a separation chamber of the air/oil separator including the steps of removing the separator element from the separation chamber without disconnecting the scavenge device attached thereto, and positioning a replacement separator element within the separation chamber, such that a scavenge device securely affixed thereto is caused to communicate with the side wall of the separator tank.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates generally to a compressor system. More particularly, the present invention relates to an air/oil separator tank for use with an air compressor.  
         BACKGROUND OF THE INVENTION  
         [0002]    In conventional air compressor systems air is compressed in a compression chamber or airend of a compressor, for example, by a set of rotary screws, and a lubricant, such as oil, is injected into the compression chamber and mixes with the compressed air. The oil is generally injected into the compression chamber for a number of reasons including cooling the air compressor system, lubricating bearings, balancing axial forces and sealing the rotary screws. Although using oil is essential for operating these types of air compressor systems, the oil must be removed from the stream of compressed air before the compressed air may be used downstream for pneumatic equipment and/or other tools.  
           [0003]    In such conventional air compressor systems, the compressed air and oil mixture discharged from the airend of the compressor flows with a high velocity into a separator tank where the air and oil of the air/oil mixture are caused to separate. The separator tank is usually cylindrical and the air/oil mixture is directed around an inner wall of a separation chamber. The combination of the centrifugal forces acting on the air/oil mixture and contact between the air/oil mixture and the inner wall of the separation chamber causes much of the oil to separate from the air/oil mixture, thereby allowing gravity to draw most of the oil downwardly into a lower portion of the separation chamber and also allowing the air to separate from the oil and flow upwardly into an upper portion of the separation chamber to achieve primary separation.  
           [0004]    In these conventional air compressor systems, the compressed air, along with some fine oil droplets or mist entrained therein, passes through a separator element placed within the upper portion of the separation chamber, thereby coalescing most of the remaining oil in the air stream to achieve secondary separation before the compressed air is transferred out of the separator tank. The coalesced oil pools in a bottom portion of the separator element and is returned to the airend of the compressor by a scavenging line.  
         SUMMARY OF THE INVENTION  
         [0005]    Conventional air compressor systems as described above typically include a lid mounted on the separator tank to hold the separator element within the separation chamber of the separator tank. The separator element must be held in place because there is an upward force on the separator element due to the pressure differential between the wet side (outer) and dry side (inner) portions of the separator element. Conventional air compressor systems include an air exit port in the lid, and typically, a minimum pressure check valve (MPCV) assembly is operatively connected to the air exit port in the lid. After passing through the MPCV assembly, the compressed air is typically sent to an aftercooler, and then the cooled compressed air may be conveyed to pneumatic equipment and/or other tools. As can be appreciated by those skilled in the art, it is generally necessary to service or replace separator elements from time-to-time. In the conventional air compressor systems described above, before a separator element can be serviced or replaced, the air discharge hose and MPCV assembly, which usually includes associated fittings, must be disconnected from the lid. This increases the time required to service or replace the separator element. Thus, there is a need for an air compressor system which eliminates the necessity of disconnecting the air discharge hose and MPCV assembly from the separator tank prior to servicing or replacing a separator element.  
           [0006]    The conventional way to remove oil from inside a separator element of the air compressor systems described above is to pass an independent scavenge tube through the lid mounted on the tank and down into an open area of the separator element. The scavenge tube extends to the bottom of the separator element and draws off the excess oil to prevent saturation of the separating media of the separator element. Positioning the scavenge tube through the lid and down into the open area of the separator element can be problematic. If the scavenge tube is too long, it may puncture the bottom of the separator element. If the scavenge tube is too short, it may not be sufficiently effective in removing the oil. In addition, before the separator element is replaced, the scavenge tube must be removed from the separator tank lid. Thus, there is a need for a scavenging device which is easy to install, which does not adversely affect the servicing or replacing of a separator element, and which also effectively removes oil from the bottom of the separator element.  
           [0007]    The present invention provides in one aspect thereof, a separator tank having an air exit port in a side wall of the tank, rather than in the lid of the tank as is the case with many known designs. Air from an air/oil mixture flows into an upper portion of a separation chamber of the tank, through a separator element positioned within the upper portion of the separation chamber, and out the air exit port in the side wall of the tank. An MPCV assembly is operatively connected to the air exit port in the side wall of the tank. Because the MPCV assembly and air discharge hose are not attached to the lid of the separator tank, in order to service or replace the separator element, the lid mounted on the separator tank is simply removed or pivoted out of the way to allow access to the separator element, without having to first disconnect the discharge hose and MPCV assembly.  
           [0008]    The present invention provides in another aspect thereof, a separator element hold down mechanism between the separator element and the lid to position the separator element within the separation chamber and in spaced relation from the lid. Air separated from the air/oil mixture will flow through the separator element, towards the lid, and out the air exit port in the side wall of the separator tank.  
           [0009]    The present invention provides in another aspect thereof, a separator element oil scavenge device which draws oil up off of the bottom of the separator element, and which transports the scavenged oil through the side wall of a separator tank. In one embodiment of the present invention, the scavenge device includes a tube which is integrally formed with the separator element. Once the tube is securely attached to the separator element and an end of the tube is located at a predetermined position relative to the bottom of the separator element, there is no need for independent adjustment of the tube relative to the bottom of the separator element and, as a consequence, no risk of making the tube too long or too short.  
           [0010]    Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims and drawings in which like numerals are used to designate like features. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]    [0011]FIG. 1 is a perspective view of an air compressor system embodying the present invention.  
         [0012]    [0012]FIG. 2 is a perspective view of a separator tank shown in FIG. 1.  
         [0013]    [0013]FIG. 3 is a cross-sectional view of a separator tank assembly shown in FIG. 1.  
         [0014]    [0014]FIG. 4 is a partial cross-sectional view of a portion of an alternative embodiment of a separator tank assembly of the present invention.  
         [0015]    [0015]FIG. 5 is a partial cross-sectional view of a portion of an alternative embodiment of a separator tank assembly of the present invention.  
         [0016]    [0016]FIG. 6 is a partial cross-sectional view of a portion of an alternative embodiment of a separator tank assembly of the present invention.  
         [0017]    [0017]FIG. 7 is a perspective view of the separator element hold down mechanism of FIG. 6.  
         [0018]    [0018]FIG. 8 is a partial cross-sectional view of a portion of an alternative embodiment of a separator tank assembly of the present invention.  
         [0019]    [0019]FIG. 9 is a partial cross-sectional view of a portion of an alternative embodiment of a separator tank assembly of the present invention. 
     
    
       [0020]    Before the embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. The use of “including” and “comprising” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items and equivalents thereof.  
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0021]    Illustrated in FIG. 1 is an air compressor system  10  embodying the present invention. It should be understood that the present invention is capable of use in other compressor systems, and the air compressor system  10  is merely shown and described as an example of one such system.  
         [0022]    The air compressor system  10  illustrated in FIG. 1 includes a compressor  14 , a motor  18 , and a separator tank  22 . Although the separator tank  22  as disclosed herein is used to separate oil from an air/oil mixture, it is contemplated that the separator tank  22  may be used to separate a volume of gas from any mixed media combination, including any gas/liquid combination. In addition, it is contemplated that the compressor  14  may be any suitable compressor, such as an oil-flooded air compressor. However, for the purposes of describing the preferred embodiment, the compressor  14  is a rotary screw compressor.  
         [0023]    The separator tank  22  may be constructed of any number of suitable materials. However, in a preferred embodiment, the separator tank  22  is a cast separator tank. Air enters the compressor  14  and is compressed by rotary screws (not shown) found within the compressor  14 . Oil is injected into the compressor  14  to lubricate the rotary screws and a gearbox (not shown) which drives the rotary screws. The oil further serves as a sealing means for the compressor  14 . The compressed air and some of the oil travel out of the rotary screws through an airend discharge opening of the compressor and into an airend inlet opening  26  (FIG. 2) in the separator tank  22 . The separator tank  22  serves to separate oil from the compressed air and also serves as an oil sump for the oil used to lubricate the rotary screws, the gearbox and other components. The compressed air and oil enter the separator tank  22  and are caused to undergo a cyclonic motion within the separator tank  22 . As the compressed air and oil are flung around an inner surface of the separator tank  22 , the oil will slide down the inner surface of the separator tank  22  and collect in the bottom of the separator tank  22 , and the air will move up and out of the; separator tank  22  for further filtering, cooling and ultimate use.  
         [0024]    Referring to FIG. 3, the separator tank  22  includes a side wall  30  and defines a separation chamber  34  having a lower portion  38  and an upper portion  42 . The lower portion  38  of the separation chamber  34  serves as an oil reservoir or sump for the oil that is separated from the air/oil mixture introduced into the separation chamber  34  via channel  46  (see also FIG. 2) during the primary separation process. A channel  50  communicates with the bottom of the lower portion  38  of the separation chamber  34 . Pressure within the separator tank  22  forces the oil collected in the lower portion  38  of the separation chamber  34  to flow through the channel  50  and back to the compression chamber of the compressor  14  to lubricate the rotary screws, the gearbox and other components.  
         [0025]    FIGS.  3 - 6  and  8 - 9  schematically illustrate separator elements  54  used in the secondary separation process. Although the illustrated separator elements  54  may have slightly different configurations, with reference to FIG. 9, each separator element  54  generally has a cylindrical body comprising inner  55  and outer  56  perforate metal shells, filter media  57  sandwiched between the shells  55  and  56 , an open top  58 , a closed bottom  62 , and an internal passage (represented by arrow  64 ) where substantially oil-free compressed air flows from the separation chamber  34  of the separator tank  22 . During the secondary separation process, oil pooled in the bottom  62  of the separator element  54  will be piped back to the compressor  14  via a scavenging device as described in detail below. It should be noted that the present invention is capable of use with many different separator elements, and the separator elements  54  are merely shown and described as examples of such separator elements.  
         [0026]    Referring now to FIG. 3, the separator element  54  is placed within the upper portion  42  of the separation chamber  34 . An annular flange  66  extends around the top portion  58  of the separator element  54 . The separator tank  22  includes a ledge  70  which extends circumferentially around an inner surface  74  of the side wall  30  of the separator tank  22 . The flange  66  of the separator element  54  rests on the ledge  70  of the side wall  30 . It should be noted that when the separator tank  22  is a cast separator tank, it is preferable for the ledge  70  to be an integrally cast member of the separator tank. As previously explained, air from the air/oil mixture introduced into the separation chamber  34  will flow upwardly into the upper portion  42  of the separation chamber  34  and through the separator element  54 .  
         [0027]    The separator tank  22  includes an air exit port  78  in the side wall  30  of the separator tank  22  for the air from the air/oil mixture that flows through the separator element  54 . An MPCV assembly  82  is operatively connected, preferably threadably connected, to the air exit port  78 . Lid  86  is mounted on the separator tank  22 . When it is desirable to service or replace the separator element  54 , lid  86  is simply removed or pivoted out of the way to provide quick and easy access to the separator element  54 , without having to first disconnect the MPCV assembly  82  from the air exit port  78 .  
         [0028]    In an alternative embodiment, a boss  90  (FIGS. 2 and 4) having a channel  94  (FIGS. 2 and 4) therethrough extends outwardly from the side wall  30  of the separator tank  22 . The boss  90  is arranged so that the air exit port  78 ′ (FIG. 4) in the side wall  30  aligns with the channel  94  to provide an air exit passageway  98  (FIG. 4) out of the upper portion  42  of the separation chamber  34 . MPCV assembly  82  (FIG. 4) is operatively connected to the channel  94  of the boss  90 . In a preferred embodiment, the separator tank  22  is a cast separator tank and the boss  90  is an integrally cast member of the separator tank  22 .  
         [0029]    Referring again to FIG. 3, during operation of the compressor system  10 , an upwardly acting resultant force within the separation chamber  34  is applied against the bottom  62  of the separator element  54 . Thus, a separator element hold down mechanism  102  is provided between the separator element  54  and the lid  86  to position and hold the separator element  54  within the separation chamber  34 . The separator element hold down mechanism  102 , which is in the shape of an annular spacer ring, engages the flange  66  (or flange  66 ′ as shown in FIG. 8) of the separator element  54  to hold the separator element  54  against the ledge  70  on the side wall  30  when the lid  86  is closed. The separator element hold down mechanism  102  positions the separator element  54  away from the lid  86 , and it also includes a plurality of apertures  106  (or  106 ′ as shown in FIG. 8) or holes which allow the air to flow through the separator hold down mechanism  102  to reach the air exit port  78  (or  78 ′ as shown in FIG. 8) in the side wall  30  of the separator tank  22 . The separator element hold down mechanism according to the present invention may comprise many different shapes and configurations, so long as it functions to position and hold the separator element within the separation chamber, and so long as it allows the air which travels through the separator element to reach the air exit port in the side wall of the separator tank.  
         [0030]    For example, with reference to FIG. 5, the separator element hold down mechanism  102 ′ includes a plurality of bolts  110  which threadably extend through the lid  86 ′ and which engage the flange  66 ′ of the separator element  54  to hold the separator element  54  against the ledge  70  on the side wall  30 . Each bolt  110  includes an O-ring seal  114  between itself and the lid  86 ′ to better seal the air space provided between the bottom of the lid  86  and the top  58  of the separator element  54 . Air flowing up, through the separator element  54  simply changes direction and flows out of the air exit port  78 ′ in the side wall  30  of the separator tank  22 .  
         [0031]    As another example, with reference to FIGS.  6 - 7 , the separator element hold down mechanism  102 ″ is a generally annular spacer ring  118  having a top ring  122 , a bottom ring  126 , and a plurality of columns  130  extending between the top  122  and bottom  126  rings, thereby defining a plurality of air passages  134 . The spacer ring  118  engages the flange  66 ′ of the separator element  54  to hold the separator element against the ledge  70  on the side wall  30  when the lid  86  is closed. Air flowing up through the separator element  54  passes through the air passages  134  on its way to the air exit port  78 ′. In an alternative embodiment, the annular spacer ring is a solid cast annular ring having an aperture therethrough to allow the air passing through the separator element to reach the air exit port.  
         [0032]    Preferably, ledge  70  on the side wall  30  of the separator tank  22  includes an annular groove  138  for receiving an O-ring seal  142  (see, e.g., FIG. 6). The O-ring seal  142  is positioned between the flange  66 ′ (or flange  66  as shown in FIG. 3) of the separator element  54  and the ledge  70  of the side wall  30  to provide an appropriate seal and to accommodate stack-up manufacturing/assembly tolerances in the separator tank assemblies shown in FIGS.  3 - 6  and  8 - 9 .  
         [0033]    As mentioned above and with reference to FIG. 9, oil mist coalesced by the secondary separator element  54  is drawn inward towards passage  64 , runs down inner shell  55  and collects at the bottom  62  of the separator element  54 . The coalesced oil is drawn out of the bottom  62  of the separator element  54  by a separator element oil scavenge device  146 . The scavenged oil is piped back to the compressor  14  for use by the compressor  14 .  
         [0034]    With continued reference to FIG. 9, the separator element oil scavenge device  146  includes a scavenge tube or pipe  150 . The tube is preferably a metal tube but, may be made of other suitable materials, such as plastic. One end  154  of the tube  150  is located near the bottom  62  of the separator element  54 . The tube  150  extends up through the passage  64  of the separator element  54 , and along and above the open end  58  of the separator element  54 . Although not shown, a support member may extend across the open end  58  of the separator element  54 . The tube  150  would then extend through the support member. The tube  150  extends back through the flange  66 ′ of the separator element  54 . The tube  150  also suitably extends through the spacer ring  118 . The tube  150  is preferably tack welded to either or both of the flange  66 ′ and support member (not shown) to locate the end  154  of the tube  150  a predetermined distance from the bottom  62  of the separator element  54 . Because the tube  150  is incorporated into the structure of the separator element  54 , during assembly of the separator tank  22 , no independent adjustment of the scavenge tube  150  is necessary to ensure that the tube  150  is spaced an optimum distance from the bottom  62  of the separator element  54 . A channel  158  is provided in the side wall  30  of the separator tank  22 . The channel  158  opens through the ledge  70  on the side wall  30  and is adapted to receive a portion of the tube  150 . An O-ring seal  162  is placed around end  164  of the tube  150  which extends through the flange  66 ′. The channel  158  is also adapted to receive the O-ring seal  162  to provide an appropriate seal.  
         [0035]    Upon assembly of the separator tank  22 , the separator element  54  is placed within the separation chamber  34  such that the end  164  of the tube  150  extending through the flange  66 ′ is received by the channel  158 . As shown in FIG. 9, the tube  150  may be used as a handle for placing and removing the separator element  54  into and from the separator tank  22 . To replace the separator element  54 , the lid  86  is opened and the separator element  54  is removed without having to first disassemble the scavenge device  146 . To reinstall a separator element  54  into the separation chamber  34 , a separator element  54  and its securely attached scavenge device is simply deposited within the separation chamber  34  as described above. Once the lid  86  is closed, the separator hold down mechanism will hold the separator element in place.  
         [0036]    [0036]FIG. 8 illustrates an alternative separator element oil scavenge device  146 ′ which includes a scavenge tube  166 , such as a Teflon tube. One end  170  of the tube  166  is connected to a fitting  174  found in the bottom  62  of the separator element  54  and the other end  178  of the tube  166  is connected to a fitting  182  extending through a channel  158 ′ in the side wall  30  of the separator tank  22 .  
         [0037]    Variations and modifications of the foregoing are within the scope of the present invention. It is understood that the invention disclosed and defined herein extends to all alternative combinations of two or more of the individual features mentioned or evident from the text and/or drawings. All of these different combinations constitute various alternative aspects of the present invention. The embodiments described herein explain the best modes known for practicing the invention and will enable others skilled in the art to utilize the invention. The claims are to be construed to include alternative embodiments to the extent permitted by the prior art.  
         [0038]    Various features of the invention are set forth in the following claims.