Abstract:
For pumps, compressors, and air or hydraulic motors with multiple cylinders such as swashplate or nutating type pumps and compressors with axial pistons arranged about a central axis, a orbit valve is connected through an eccentric and bearing to the shaft and caused to orbit around an axis of the shaft by rotation of the shaft. Grooves in the orbit valve surface alternately connect a port in each cylinder with a fixed intake and an exhaust port in the valve plate ties for optimal performance without depending on pressure differential otherwise needed to open and close passive flapper or poppet-type valves. The orbiting motion provides direct acting valve action for intake and exhaust functions with much slower relative motion and far less friction than a rotating valve of similar size.

Description:
[0001]    The present application claims priority from U.S. provisional application 60/610,013 filed Sep. 15, 2004. 
     
     FIELD 
       [0002]    The present invention comprises valves for the porting of intake and exhaust in reciprocating pumps, including vacuum pumps and compressors, and more particularly in multi-cylinder pumps such as swashplate or nutating or wobble-piston type pumps or pumps with axial pistons arranged about a central axis. 
       BACKGROUND 
       [0003]    Passive valves, such as flapper, poppet or umbrella valves, are used for intake and exhaust porting for reciprocating piston pumps. A flapper valve is typically made of a thin, flat material. Stainless steel has been used for higher pressure flapper valve applications and elastomers have been used for small, low-pressure flapper valve applications. Poppet valves are typically made of a harder material that is biased against a valve plate using a spring. An umbrella valve is usually made of an elastomeric material and includes a built-in attachment method for retaining itself against the valve plate while covering several small holes. Each of these passive valve systems are activated by fluid pressure acting against the valve such that fluid is allowed to pass in one direction only. 
         [0004]    Passive valve systems are limited by the speed at which they can respond and tend to become more restrictive and much less effective at higher speeds. 
         [0005]    Direct-acting valve systems are known. Cardillo, U.S. Pat. No. 5,058,485, discloses a direct-acting orbiting ring valve for a hydraulic swashplate type pump. White, U.S. Pat. No. 4,877,383, discloses a direct-acting valve such as an orbiting valve for a gerotor device. U.S. Pat. No. 6,224,349 discloses a direct-acting orbiting valve for a swashplate type pump 
       SUMMARY 
       [0006]    The present invention provides a direct-acting, orbiting valve system for reciprocating piston pumps, including compressors and vacuum pumps, that provides greater pumping efficiency at higher speed ranges than currently feasible with passive valving systems. 
         [0007]    The invention provides both intake and exhaust valve functions using a single orbiting valve member to alternately route the cylinder ports to separate intake and exhaust ports. In addition, a single orbiting valve member can be provided with port routing for separate pressure and vacuum cylinders connected to the same valve plate of a multi-cylinder machine. 
         [0008]    The invention reduces the ultimate torque required and the frictional losses associated with an orbiting valve member by allowing the member to rotate slightly under conditions of stiction creating a twisting motion that results in a mechanical advantage to more easily break away the stiction-adhered surfaces of the orbiting valve and the valve plate as compared to a rotary valve. 
         [0009]    In one embodiment of the invention, routing of intake and exhaust is accomplished by using concentric grooves in the orbiting valve to interconnect cylinder ports in the valve plate with the intake and exhaust ports in the valve plate. In an alternative embodiment the invention provides routing of intake and exhaust with discrete, non-concentric groove segments in the orbiting valve member. In this case the orbiting valve is constrained from rotating by a compliant member. 
         [0010]    The foregoing and other aspects of the invention, such as the inventions features, objects and advantages, are apparent in the brief description of the drawings, detailed description, attached drawings and attached claims. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0011]      FIG. 1  is a perspective view of a reciprocating pump which embodies the features of one embodiment of the present invention; 
           [0012]      FIG. 2  is a side view of the pump shown in  FIG. 1 ; 
           [0013]      FIG. 3  is a top view of the reciprocating pump shown in  FIG. 1 ; 
           [0014]      FIG. 4  is a bottom view of the reciprocating pump shown in  FIG. 1 ; 
           [0015]      FIG. 5   a  is a sectional view taken along section line  5 - 5  of  FIG. 2 ; 
           [0016]      FIG. 5   b  is a perspective of the cross section shown in  FIG. 5   a;    
           [0017]      FIG. 6   a  is a perspective view of the orbiting valve of the pump of  FIG. 1 , looking into a face surface of the valve having two concentric grooves therein; 
           [0018]      FIG. 6   b  is a plan view of the orbiting valve&#39;s grooved surface shown in  FIG. 6 ; 
           [0019]      FIG. 7  is a perspective view of the valve plate of the pump of  FIG. 1 , looking into a face surface of the valve plate having three cylinders emanating therefrom; for convenience of illustration the plate has been shown with a squarish shape as opposed to its actual round shape as indicated in  FIGS. 5   a ,  5   b;    
           [0020]      FIG. 8  is a perspective view of the valve plate shown in  FIG. 7 , looking into a face surface opposite the surface shown in  FIG. 7 ; 
           [0021]      FIG. 9  is a face plan view of an assembly of components from the pump of  FIG. 1 , wherein the assembly has a valve plate having three cylinders, an orbiting valve, and an eccentric interfacing the valve plate with the orbit valve; for convenience, the orbit valve circumferential projection seen in  FIG. 5   a  is not shown; also for convenience of illustration the valve plate has been shown with a squarish shape as opposed to its actual round shape as indicated in  FIGS. 5   a ,  5   b ; wherein the view looks towards the pump&#39;s motor end, away from the pump end opposite the motor, and into the face surface of the valve plate having the cylinders emanating therefrom; 
           [0022]      FIGS. 10   a - 10   e  are plan views generally the same as shown in  FIG. 9 , except for further convenience, only one cylinder and its associated cylinder port are shown; the Figures show the orbiting valve&#39;s sequence relative to stated positions of the piston; 
           [0023]      FIG. 11  is a partial cross sectional view taken along a longitudinal axis of a pump having an alternative embodiment of the invention, wherein the pump has its orbit valve eccentric on the opposite side of the valve plate as compared to the placement of the orbit valve in  FIG. 5   a;    
           [0024]      FIG. 12   a  is a face plan view of an assembly of components from a pump of the type shown in  FIG. 1 ; the view shows an alternative embodiment of the invention, wherein the assembly has a multi cylinder valve plate, for convenience, only one cylinder is shown; an orbiting valve having multiple segmented intake through ports and multiple segmented exhaust grooves, again for convenience, only one exhaust segment is shown; and an eccentric interfacing the valve plate with the orbiting valve, wherein the view looks towards the pump&#39;s motor end, away from the pump end opposite the motor, and into the face surface of the valve plate having the cylinders emanating therefrom; 
           [0025]      FIG. 12   b  is a perspective view of the assembly shown in  FIG. 12   a ; for convenience, the arms shown emanating from the orbiting valve in this perspective view were omitted from the plan view in  FIG. 12   a;    
           [0026]      FIG. 13  is a top perspective view of the orbiting valve eccentric of the pump of  FIG. 1 ; 
           [0027]      FIG. 14  is an end perspective view of the shaft, orbiting valve eccentric and orbiting valve of  FIG. 1  assembled together. 
       
    
    
     DETAILED DESCRIPTION  
       [0028]    Referring now to  FIGS. 1-5   b , nutating or wobble-piston type compressor or pump  100  has a housing  102 . The housing  102  encloses a crank case volume  104 . The pump has certain main drive components in the housing. The main drive components in the housing include shaft  18 , eccentric  64 , eccentric bearing  62 , wobble member  60 , and cross-type universal joint  56 . Universal joint  56  has two of its opposed arms journalled or coupled to connector  59  and the other two of its opposed arms journalled or coupled to wobble or yoke member  60 . 
         [0029]    The wobble member  60  has three arms  74  all of which are the same as each other. Only one arm  74  is shown. Each arm has, at its end, a ball head  76 . 
         [0030]    Pump  100  has three pistons, all of which are the same. Only one piston  14   a ,  14   b  is fully shown. Each piston has a piston head  14   b  and piston rod  14   a . Each piston rod  14   a  is hollow and contains a socket halve  78 . Each wobble member&#39;s ball head  76  is coupled to a piston rod  14   a  via the socket half  78 . 
         [0031]    As can be seen in  FIGS. 7 and 9 , each piston is associated with a respective cylinder  20   a ,  20   b  and  20   c . Each cylinder has associated with it a cylinder port  28   a ,  28   b  and  28   c . See  FIGS. 7 ,  8  and  9 . The cylinder ports  28   a ,  28   b ,  28   c  each comprise elongated cylinder groove port portions  28   a ″,  28   b ″,  28   c ″ and small centrally located oval cylinder through port portions  28   a ′,  28   b ′,  28   c ′. The small oval portions are the only portions of the cylinder ports that actually pass through the valve plate. The center of UV joint  56  is aligned along the center the shaft axis  18   a.    
         [0032]    During operation of pump  100  drive shaft  18  is rotated by the motor  58 , the stator of which is affixed to the end cover  52 , which is affixed, via wall  103 , to housing  102  to enclose orbiting valve  16 , orbiting valve eccentric  30 , orbiting valve eccentric bearing  32  and counter moment mass  54 . 
         [0033]    As the motor shaft  18  rotates, eccentric  64 , through bearing  62 , causes wobble member  60  to wobble and thereby drive rod  14   a  in a predominantly reciprocating motion. Orbiting valve eccentric  30 , acting through orbiting valve eccentric bearing  32 , causes orbiting valve  16  to orbit about the shaft centerline  18  as it slides relative to the valve plate  25 . Two concentric grooves  22  and  24 , in the orbiting valve  16 , alternately slide over the cylinder ports  28   a ,  28   b  and  28   c  to provide sequenced fluid communication with intake port  27  and exhaust port  26 . See  FIG. 9 ,  10   a - 10   e . Groove  22  can be described as a pressure or exhaust groove and groove  24  can be described as an intake groove. The dashed line in  FIGS. 5   a ,  5   b  indicates fluid communication between exhaust port  26  shown in  FIG. 9  and connector tube  46  shown in  FIG. 5   a . Fluid intake is routed through port  44  of the attenuation chamber  48  , through ports  42  into the crankcase chamber  104  and then through valve intake port  27 . The arrows in  FIGS. 5   a ,  5   b  show the fluid flow direction. 
         [0034]      FIG. 5   a  and  FIG. 5   b  show piston rod  14   a  in a top dead center position such that cylinder through port  28   a  is no longer connected to exhaust groove  22  or intake groove  24 . 
         [0035]    Now referring more particularly to  FIGS. 10   a - 10   e , the orbiting valve sequence can be further seen. In these Figures, for ease of reference, only one cylinder  20   a  and its associated cylinder port  28   a  are shown. Also, for ease of reference, the projection  16   c  is not shown. Each of the other cylinders  20   b ,  20   c  are going through exactly the same sequence except the cylinders are 120° out of phase with each other. Looking into the valve plate  16  from the cylinder side, the direction of orbit valve  16  is indicated by arrow  70  and is counterclockwise. The angular orientation of the shaft  18  relative to orbit valve  16  during the sequence is marked by darkened area  30   a . The degrees of rotation can thus be correlated to the piston&#39;s position. 
         [0036]    In understanding the below description of how  FIGS. 10   a - 10   e , depict the orbit valve&#39;s sequencing, it is important to note that the orbiting valve being sequenced by eccentric  30 , relative to the piston, is phased to be 90° out of phase with the motion of the pistons. At the start of the sequence,  FIG. 10   a , the piston is at the top dead center (TDC) position, see  FIG. 5   a  and  5   b . The cylinder port  28   a  is not in communication with either the exhaust or pressure groove  22  or the intake groove  24 . The intake groove  24  is ready to communicate with the cylinder port  28   a . In  FIG. 10   a  the center  16   a  of orbiting valve  16  is shown displaced to the left. The direction of displacement, if an “x, y” graph  17 , oriented about shaft  18 &#39;s center line, were superimposed over  FIG. 10   a , would be “−x”. The amount of displacement is determined by the offset  30   b  ( FIG. 13 ) of the orbiting valve eccentric  30  from shaft centerline  18   a . The center  16   a  of orbit valve  16  is not displaced along the y axis when rod  14   a  is in the top dead center position. The orbit valve center  16   a  is thus centered vertically with respect to shaft  18 . In the top dead center position, the orbiting valve center  16   a  is located predominantly 90 degrees counterclockwise from the top cylinder  20   a  shown in  FIG. 10   a.    
         [0037]    Moving on in the sequence,  FIG. 10   b , the piston has traveled halfway down (away from valve plate  25 ) the cylinder  20   a . Cylinder through groove  28   a ″ is in communication with intake groove  24 . Next,  FIG. 10   c , the piston has traveled to bottom dead center (BDC), a maximum distance from valve plate  25 . Cylinder port  28   a  is not in communication with either the intake  24  or pressure groove  22 . As the piston moves from BDC position, to a position approximately at the center of the upward stroke, the cylinder through port  228   a ′ is not in communication with either intake nor exhaust groove. This allows the pressure to build up within the cylinder to a level nearly equal to that pressure in the exhaust groove. Next,  FIG. 10   d , the piston has traveled midway up the cylinder, i.e., at middle of upstroke and point of maximum compression. Finally, in  FIG. 10   e , the piston is 45° before TDC. The cylinder port  28   a , by way of cylinder groove portion  28   a ″, is open to the exhaust or pressure groove  22 . The relative position of the other ports  28   b ,  28   c , when the piston is 45° before TDC , can be seen in  FIG. 9 . 
         [0038]    In the above described sequence, the orbit valve  16  is not restrained from rotation about its own axis, but since the grooves  22  and  24  are circular the orbit valve can rotate as well as orbit, although the rotation about its own axis does not affect its operation. In addition, the combination of bearing  32  and the friction of the orbit valve  16  against the valve plate  25  would result in the motion being largely orbital with only little, if any, rotation. Further the grooves  22  and  24  do not pass through the orbit valve to form a through space. 
         [0039]    The use of a cylinder port with a grooved portion  28   a ″ and a through portion  28   a ′ is believed to be advantageous over the use of a simple through port. Also, having the inner groove  22  as the exhaust groove  22  , as opposed to the outer groove, is believed to be advantageous in that the surface area forming the inner groove is less than the outer groove. The smaller area reduces the forces on the orbit valve  16  resulting from the fluid pressure. The orbiting valve  16 , however, could be configured with the outer groove as the exhaust groove. 
         [0040]    A further feature that can be included in a pump embodying the invention is an axial spring bias force  86  that may be provided between the orbiting valve  16  and a stationary structure attached to the housing, such as end cover  52 . The spring serves to overcome the net separation forces caused by the difference between (1) the fluid pressure acting on an area of the surface of the orbiting valve  16  contacting the valve plate  25  and (2) the fluid pressure acting on the surface of the orbit valve opposite the orbit valves sealing surface. The spring assures sealing between the land areas surrounding the grooves  22 ,  24  and the valve plate  25  of housing  102 . Alternatively, one or more axially extending springs could provide a biasing force between the orbiting valve  16  and eccentric  30 . To improve biasing of the orbit valve, a circumferential projection  16   c  is provided on the valve&#39;s end wall surface opposite the valve surface having the concentric grooves. The circumferential projection defines a space to receive an end coil of spring  86 . The projection of course does not have to be continuous. As an alternative to a projection, a groove can be provided to receive an end coil of the spring. For convenience, the spring  86  is not shown in its actual relative coiled and flexed state. 
         [0041]    Referring to  FIGS. 12   a  and  12   b , an alternative embodiment having a segmented orbit valve with a combination of grooved segments and through segments is shown. The associated valve plate  225 , would have  3  cylinders, for convenience only one cylinder  220   a  is shown. The valve plate would have three cylinder ports, again for convenience only, port  228   a , comprising groove portion  228   a ″ and through portion  228   a ′ is shown. The valve plate further has three exhaust ports; for convenience only one  226   a  is shown. 
         [0042]    The orbiting valve  216  shown in  FIGS. 12   b  and  12   a  has three intake segments  224   a ,  224   b ,  224   c ; each would be uniquely associated with one of the three cylinders. In the shown embodiment intake  224   a  is associated with cylinder  220   a . The intake segments completely pass through the orbit valve. Having the intake segments as through apertures, allows for direct intake into the associated cylinder port, thus eliminating the need for any intake ports in the valve plate. 
         [0043]    The orbiting valve of  FIGS. 12   a  and  12   b  would also have three grooved segmented exhaust ports; for convenience only exhaust port  222   a  is shown. Each exhaust port segment is uniquely associated with a cylinder and a cylinder port. In the shown embodiment grooved exhaust segment  226   a  is associated with cylinder port  228   a  and cylinder  220   a . The exhaust segments do not pass through the orbit valve. The orbit valve would have a projection similar to the projection  16   c  shown in  FIGS. 5   a , 5   b . For convenience, the projection is not shown in  FIGS. 12   a ,  12   b.    
         [0044]    Although the embodiment in  FIGS. 12   a  and  12   b  show their intake segment as passing through the orbit valve; they do not have to pass through the orbit valve. In this case, proper intake porting through the valve plate would have to be provided. Further, in this case, it would be possible to have the exhaust segments as pass through holes thereby eliminating the need for exhaust ports in the valve plate. In this case, the cavity in which the orbit valve is enclosed would have to be pressure sealed. The pressure allowed to build up in the cavity could be made sufficient to overcome the net separation forces between the valve plate and orbit valve so as to eliminate the need for an external biasing force member such as spring  86 . The amount of pressure allowed to act as the biasing force should not be so great as to create undue friction forces between the orbit valve and valve plate. The pressure could be regulated by a pressure regulation port in the cavity or some or some other pressure regulator. 
         [0045]    The orbit valve  216  must be prevented from rotating relative to the housing by use of any of several possible methods including but not limited to an Oldham coupling, one or more idler crank mechanisms, one or more torsional springs, one or more leaf springs, or other compliant mechanisms either separately attached between the disk and the stationary housing or integrated as a monolithic member with the disk itself. For convenience, shown only in the perspective view  12   b , are four integral flexible compliant arms  216   d.    
         [0046]    A spring and projection similar to spring  86  and projection  16   c  could also be used to form a resilient compliant. In this case, the projection used to receive an end coil of the spring would be sized so that the circumferential projection forms a cavity which permits the end coil to snap-fit into the cavity. The snap-fit would serve to couple the spring to the orbit valve with a sufficient frictional fit to resist the torsion forces imparted to the orbit valve by the eccentric. If a groove were used to receive the spring, the groove could have a cavity therein to receive a spring end and thereby limit the orbit valves rotation. 
         [0047]    Referring to  FIGS. 12   a ,  12   b , orbit valve  216  could be used with a pump having compression and vacuum cylinders. The cylinders would be a combination of compression and vacuum cylinders. Each cylinder would be associated with a combination of orbit valve intake/exhaust cavities, which could be combinations of grooves, or through ports. The valve plate and orbit valve would be configured to interconnect the pressure and vacuum cylinders provided within the same pump to the appropriate intake or exhaust ports in the valve plate to sequence and to provide both vacuum and pressure pumping capability with separate fluid circuits; or to provide a combination of pumping and motoring using either a pressure or vacuum fluid source and/or an electric motor in any combination. 
         [0048]    Referring to  FIG. 13  the eccentric  30  could include a portion (not shown) that acts as a counter weight to dynamically balance the primary radial dynamic forces created by the orbiting motion of the orbit valve  16 . In this case counter moment mass  54  would contain a counter moment mass to dynamically balance both the primary drive mechanism unbalance moment of the pump or motor and the unbalance moment created by the orbit valve and its eccentric counter mass being located in two different axial planes. 
         [0049]    In still another aspect of the invention, the orbit valve eccentric  330  may be on the same side of valve plate  325  as the eccentric  64 . See  FIG. 11 . In this case, the eccentric  330  is coupled directly to eccentric  64 . Eccentric  64  imparts an orbiting motion to eccentric  330  by way of eccentric bearings  332 . Eccentric  330  imports an orbiting motion to orbit valve  316  with coupling  300 . 
         [0050]    Although the orbit valve cavities  22 ,  24  have been described as grooves  22 ,  24 , they can also be passages, channels or ducts. Additionally, although both  22  and  24  are described as grooves, they could comprise a combination of grooves and pass through apertures. In this case the porting of the valve plate would follow the principles described with regards to  FIGS. 12   a ,  12   b . The orbit valve can have a variety of shapes beyond those shown or described. The valve plate and housing can also have a variety of shapes beyond those disclosed. 
         [0051]    It should be noted that the term coupling is used inclusively herein to cover both direct and indirect coupling. For instance the shaft  18  is coupled to the wobble member  60  by way of an indirect coupling. The shaft is also coupled to the piston  14   a ,  14   b  by way of an indirect coupling. 
         [0052]    Varying embodiments of the invention have been described in considerable detail. Many modifications and variations to the embodiments described will be apparent to a person of ordinary skill in the art. Therefore, the invention should not be limited to the embodiments described.