TECHNICAL FIELD 
     The present invention relates to pneumatic parts feeders for separating, orienting and continuously feeding parts, and particularly to parts feeders in which a circulating air flow or vortex is generated. 
     BACKGROUND OF THE INVENTION 
     Devices are known which take parts such as springs or O-rings, and the like, and separate or untangle and orient the parts in a predetermined manner, facilitating use of the parts in subsequent manufacturing operations. 
     The patent publication DE102008054106 describes a pneumatic parts feeder comprising a cylinder in which a vortex is induced by tangentially aligned air inlets near the lower end of the cylinder and a helical rib provided on the cylindrical wall. The vortex entrains the parts, which are thereby singularised and rise up the helical rib toward an outlet near the top of the cylinder. 
     The publication DE4442337 describes a pneumatic parts feeder comprising a conical bowl in which a vortex is induced by a tangentially directed air jet provided at the top of the bowl. An aperture is provided at the narrowest, lowermost section of the bowl through which parts to be fed are injected by a piston. The vortex entrains the parts, which are thereby singularised and rise up the wall of the bowl toward a tangentially aligned discharge outlet near the top of the bowl. Only the parts having a specified orientation are able to pass through the discharge outlet. 
     These machines have a simple, low-cost construction providing cost effectiveness and reliability, however there is a need for improvements in this technology which retain its advantages while addressing some of the operational drawbacks that have been identified. These operational drawbacks include the relatively high air flow rate required to entrain the products, and the flexibility of operation, particularly the ability to readily reconfigure the machine to feed different parts. In addition, it has been found that oversize parts, or parts which are defective (e.g. broken or deformed) or bound together (e.g. tangled), degrade machine performance and are difficult to remove. It is an object of the present invention to overcome or substantially ameliorate the above disadvantages or, more generally, to provide an improved pneumatic parts feeder. 
     DISCLOSURE OF THE INVENTION 
     According to one aspect of the present invention there is provided a parts feeder comprising: 
     a vortex chamber having a wall disposed generally symmetrically about an axis; 
     an outlet port in the vortex chamber through which parts are fed to an outlet channel exiting the vortex chamber; 
     a vortex generator disposed at one end of the vortex chamber for generating a vortex in the vortex chamber; and 
     at least one opening extending through the vortex generator, such that parts may pass out of the vortex chamber through the opening. 
     Preferably the vortex chamber tapers in an axial direction between a narrow end and a broad end, and the vortex generator is disposed proximate the narrow end. 
     Preferably the wall is circular in cross section and frusto-conical. 
     Preferably the outlet channel extends tangentially to the wall. Preferably the outlet channel extends tangentially to a spiral path on the wall along which the parts are impelled by the vortex. Preferably the outlet port is disposed intermediate the narrow end and broad end. 
     Preferably the vortex chamber further comprises an annular wall fixed to the broad end, the annular wall defining a central aperture from which air may escape the vortex chamber. Preferably the annular wall lies in a plane substantially perpendicular to the axis. 
     Preferably the parts feeder further comprises an inlet for feeding parts into the vortex chamber, the inlet being disposed opposite the one end, most preferably proximate the broad end. Optionally, parts may be introduced into the vortex chamber by way of the at least one opening. Preferably the inlet is substantially axially aligned. Preferably a mouth of the inlet projects axially through the central aperture in the annular wall. 
     The vortex generator may comprise an axial flow fan, the fan comprising an impeller mounted to rotate about the axis, the impeller having a plurality of blades, and wherein the at least one opening comprises a plurality of openings between adjacent blades. The impeller may comprise a hub to which the blades are fixed and the at least one opening extending axially through the hub. A motor for turning the impeller may be mounted coaxially with the impeller, or else eccentrically with the impeller. 
     The vortex generator may comprise an axially symmetrical generator body through which the at least one opening extends, flow-directing means fixed to the generator body for producing an air flow with a tangential component, and an air supply for providing air to the flow-directing means. The generator body may be substantially cylindrical, but optionally the generator body may be tapered in the axial direction in like manner to the wall of the vortex chamber. The air supply may comprise a fan, compressor or reservoir of compressed air. The air supply may comprise an air flow amplifier. 
     The flow-directing means may comprise a nozzle fixed to the generator body and configured to direct a jet of air from the air supply. The nozzle may direct the jet of air in a direction with both an axial component and component substantially tangential to a surface of the generator body. The nozzle may comprise an air flow amplifier. 
     The flow-directing means may comprise static blades fixed within the generator body, wherein the at least one opening comprises a plurality of openings between adjacent static blades, and wherein air from the air supply passes through the plurality of openings between adjacent static blades. 
     The flow-directing means may comprise one or more passages formed in the generator body. The one or more passages may comprise helical passages extending between axially opposing ends of the generator body. 
     In another aspect the invention provides for the use of a parts feeder substantially as described above, wherein the outlet port has a profile complementary to the form of the parts. Preferably operation of the parts feeder comprises aligning the axis substantially upright and periodically stopping the vortex generator to allow parts to drop out of the vortex chamber through the at least one opening. 
     This invention provides a parts feeder which is effective and efficient in operational use, has an overall simple design which minimizes manufacturing costs and maximizes performance, and which addresses problems with the prior art machines. By providing a vortex generator at the lower end of the vortex chamber, with an opening extending therethrough, defective parts, oversize parts, or parts which are tangled or held together may readily be removed, and the machine is readily reconfigured to feed different parts. In addition, it has been found that the air flow rate required to entrain the products can be reduced. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Preferred forms of the present invention will now be described by way of example with reference to the accompanying drawings, wherein: 
         FIG. 1  is a schematic exploded isometric view of a first embodiment of the parts feeder according to the invention; 
         FIG. 2   a  is a schematic isometric view of the parts feeder of  FIG. 1  assembled; 
         FIG. 2   b  is schematic section in a transverse plane through the outlet port of the parts feeder of  FIG. 2   a;    
         FIG. 3   a  is a schematic isometric view of a second embodiment of the parts feeder according to the invention; 
         FIG. 3   b  is schematic section in a transverse plane through the outlet port of the parts feeder of  FIG. 3   a;    
         FIGS. 4 to 7  are schematic sectional views in longitudinal planes showing first through fourth alternative vortex generators respectively, for use with the parts feeder of the invention; 
         FIG. 8  is a schematic isometric view of a fifth alternative vortex generator; 
         FIGS. 9 and 10  are side and top views of the vortex generator of  FIG. 8 ; 
         FIG. 11  is a schematic top view of the vortex generator of the parts feeders of  FIGS. 1-3 ; 
         FIG. 12  is a schematic, partially sectioned side view of the vortex generator of  FIG. 11 , and 
         FIG. 13  is a schematic sectional view in longitudinal plane showing a sixth alternative vortex generator. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to  FIGS. 1 ,  2   a  and  2   b , a parts feeder  10  according to a first embodiment of the invention generally includes a vortex chamber  11 , a vortex generator  12  and an outlet part  13 . The vortex chamber  11  has a wall  14  which is rotationally symmetric about an axis  15 . As used herein, the term “axial” refers to a direction substantially parallel to the axis  4 . As illustrated, the wall  14  may be frusto-conical with a circular cross section, tapering in the axial direction between a narrow end  115  and a broad end  16 . Circular rims of the ends  115 ,  16  may lie in respective parallel planes transverse to the axis  15 . A slotted outlet port  23  may be provided in the wall  14  intermediate the ends  115 ,  16  and sized to removeably receive the outlet part  13 , which may have a bar-like form. An annular wall  18  of planar form may be fixed to the broad end  16  so as to form an inwardly projecting lip bounding a central aperture  19  from which air may escape the vortex chamber. Holes (not shown) may be provided in the wall  14  proximate the end  115 , through which air may be drawn into the vortex chamber  11  by the vortex. 
     A funnel  20  may have a conical mouth  21  and a stem  22 , which projects into the central aperture  19 , and the funnel  20  may be symmetrical about axis  15 . With the mouth  21  uppermost the funnel  20  provides an inlet for dropping parts into the vortex chamber  11 . 
     The vortex generator  12  is shown schematically and is disposed at the narrow end  115  for generating a vortex that rises up through the vortex chamber  11 . An opening  29  may extend between axially opposing ends of the vortex generator  12 . Parts are entrained in the vortex produced by the vortex generator  12  and spiral up through the vortex chamber  11 . 
     An outlet channel  26  (indicated by dashed lines in  FIG. 1 ) may extend through the outlet part  13  from an axially elongated mouth in an elongate side  24  to an aperture  25  at one axial end. The outlet channel  26  in the outlet part  13  communicates with the outlet port  23  in the vortex chamber  11  and may be partially curved, having a first concave portion joining tangentially with adjacent wall  14  (a first axis  27  is shown extending through this intersection, tangentially to both the outlet part  13  and the wall  14 ). The outlet channel  26  may then extend linearly in the direction of a second axis  28  through the aperture  25 . The outlet port  23  and partially curved outlet channel  26  have a cross section complementary to the parts to be separated, and thus define an orientation of the parts. By making the outlet part  13  removably mounted to the vortex chamber  11  the parts feeder can be readily reconfigured to suit different parts. 
     The operation of the parts feeder is described below with respect to a second embodiment shown in  FIGS. 3   a  and  3   b , which differs from the parts feeder of  FIGS. 1 ,  2   a  and  2   b  only in respect of the outlet part  113 . Rather than being curved, the outlet channel  126  (indicated by dashed lines in  FIG. 3 ) is straight, and extends linearly between the part outlet port  23  and the aperture  25 , which are at longitudinally opposing ends of the outlet part  113 . Air flow from an air supply (not shown) such as a fan, compressor or reservoir of compressed air is indicated by arrow  30  and is supplied to the vortex generator  12 . Bulk parts  31 , such as O-rings or springs, dropped into the vortex chamber  11  through the funnel  20  fall to the narrow end  115  where they are entrained in a vortex and are thereby separated from one another and orientated. The major part of this circulating air flow exits the vortex chamber  11  through the annular section of central aperture  19  about the stem  22 . The parts  31  individually follow a spiral path  32  along the wall  14 , rising toward the broad end  16 . 
     Outer surfaces of the parts may roll around the surface of the wall, and this action combined with the aerodynamic forces serve to orient the parts in a like manner. The wall is preferably smooth, but optionally, a spiral track (such as one or more grooves in the wall or raised ribs—not shown) may be formed in the wall  14  between the vortex generator  12  and part outlet port  23  to assist in guiding the parts toward the outlet port  23 . 
     Parts  31  propelled along the spiral path  32  and in proper alignment matched with the alignment of the outlet port  23  can thus exit the vortex chamber  11  in a tangential direction to the spiral path  32  via the outlet port  23 . As only one part  31  can pass through the outlet port  23  at a time the parts  31  move successively along the outlet channel  126  to exit the parts feeder  10 . An air jet (not shown) may assist in transmitting the parts  31  through the outlet channel  126 . 
     Stopping the vortex generator  12  allows faulty parts, or parts which are held together etc so as to be unable to individually exit the machine as described above, to drop through the aperture  29 . Optionally, air flow through the vortex generator  12  may be reversed to extract parts through the aperture  29 . The vortex generator  12  may be stopped periodically as required depending upon observations of a technician of the contents of the vortex chamber  11 , such as through a transparent wall or window in the wall. Alternatively, sensors comparing the input numbers of parts (or part weight) delivered to machine, and the output numbers may trigger an alarm or automatic stopping of the vortex generator  12  to allow the vortex chamber  11  to be emptied. 
       FIGS. 4 to 7  illustrate alternative vortex generators  112 ,  212 ,  312 ,  412  which are axial flow fans with blades  35  mounted to rotate about the axis  15 , wherein blade rotation imparts swirl to the air flow to generate the vortex. 
     Referring to  FIG. 4 , vortex generator  112  has a cylindrical shroud  36  enclosing an impeller  45  comprising blades  35  fixed to a hub  37 . The blades  35  may be rotated about the axis  15 , for instance, by a coaxial motor  39  and gearbox  38 . Parts-transmitting openings through the vortex generator  112  are provided by the openings  129  between adjacent blades  35 , thus with blade rotation slowed sufficiently, stopped or reversed the parts  31  may drop or be drawn out of the vortex chamber  11  through the openings  129 . 
     In the vortex generator  12  of  FIG. 5  the impeller  145  has a hub  137  to which the blades  35  are fixed is hollow, and may be turned as by an endless belt  40  and pulley  41  driven in turn by the motor  39  and gearbox  38 . In addition to the openings  129 , the opening  229  extending axially through the hub  137  can pass the parts  31 . 
       FIG. 6  shows an impeller  245  in which the blades  35  are fixed to a peripheral ring  44 , with an opening  329  provided between the inner edges of the blades through which the parts  31  can pass. 
     An impeller  345  is shown  FIG. 7  in which the blades  35  are fixed between a peripheral ring  44  and a hollow hub  137 , with the opening  229  provided through the hub  137  for the passage of parts, in addition to the openings  129  provided between the blades  35 . The impeller may be turned as by wheel  45  engaged with the ring  44 , and rotated in turn by the motor  39  via the gearbox  38 . 
       FIGS. 8 to 10  illustrate an alternative vortex generator  512  which includes a cylindrical, tubular body  47  concentric with axis  15  and through which the opening  29  extends. An elongate nozzle  48  may have a circular cross section and may extend through the tubular body  47  and end flush with the internal wall  49 . As best seen in  FIG. 10 , an air jet introduced through the nozzle  48  from an air supply has a component tangential to the wall  49  for inducing a spiral, swirling flow. As best seen in  FIG. 9  the nozzle  48  may be inclined at a helix angle  50  to a transverse plane  51  to impart an axial component to the rotating air flow generated in the body  47 . 
       FIGS. 11 and 12  illustrate the vortex generator  12  of  FIGS. 1 ,  2   a ,  2   b ,  3   a  and  3   b , generally having the form of a tubular body  147  concentric with axis  15 . The body  147  comprises concentric tubular inner and outer members  60 ,  61  with outer and inner walls  62 ,  63  engaged with one another. Disposed between the outer and inner walls  62 ,  63  are passages  65  which may be helical and formed in one of the walls  62 ,  63 . The passages  65  may extend between axially opposing ends of the vortex generator  12  and have like dimensions, and be substantially equally circumferentially spaced. Air from a supply may be simultaneously directed into all of the passages  65 , as from an annular conduit (not shown) connected to the lower end  115 . In this manner each passage  65  generates an air stream in the vortex chamber  11  having both tangential and axial components. 
     Yet another alternative vortex generator  612  is shown in  FIG. 13 , in which static blades  70  are fixed within a tubular body  247 . In this embodiment air from the air supply passes through the openings  129  between adjacent static blades  70 , and the same openings  129  serve to pass the parts when the vortex generator  12  is not operating. 
     Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope thereof.
A parts feeder has a vortex chamber with a wall disposed generally symmetrically about an axis and into which bulk parts are fed. A vortex generator disposed at a narrow end of the chamber generates a spiral vortex that rises up the wall. Parts entrained in the vortex are separated and oriented by the vortex. Properly oriented parts are successively able to pass through an outlet port to exit the vortex chamber; thus continuously feeding parts. An opening extends through the vortex generator. Defective parts, oversize parts, and parts which are tangled or held together may readily be removed from the vortex chamber through the opening.