Abstract:
An oscillating variable displacement ring pump provides both positive and variable displacement. A housing circumscribes a pump chamber. The pump chamber encases an oscillating ring driven by a crank assembly. The ring encircles an end of the crank assembly. The crank assembly includes an annular spacer that rolls inside the ring. When the pump chamber is sealed, rotation of the crank assembly causes ring oscillation in the chamber. Ring oscillation creates vacuum pressure, which draws substances into pump chamber via an inlet port while pumping out substances of the pump chamber via an outlet port. A valve within the pump chamber contacts the ring and follows ring oscillation to help separate incoming substances from outgoing substances. The pump can include an adjustable internal by-pass means to control the volume and pressure of substances delivered by the pump.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of U.S. application Ser. No. 11/818,781 filed Jun. 15, 2007, which is incorporated by reference herein in its entirety. 
    
    
     TECHNICAL FIELD 
     The invention relates to the field of variable displacement pumps. In particular, the invention relates to an oscillating variable displacement ring pump that draws and delivers substances, such as liquids, into and out of a pump chamber by movement of a displacement ring. 
     BACKGROUND 
     Displacement pumps can take the form of gear pumps, vane-type pumps and oscillating slide pumps. With these forms of pumps, the volume of substances displaced or delivered is typically fixed due to the physical dimensions of the pumps and cannot be easily varied. It is, therefore, desirable to provide a pump that can be easily changed to vary the amount of substances displaced or delivered. 
     SUMMARY 
     An oscillating variable displacement ring pump is provided. In one embodiment, the pump can have a housing circumscribing a pump chamber. The pump chamber includes an inlet port and an outlet port. The pump chamber encases an oscillating variable displacement ring. A valve within the pump chamber contacts the ring to help isolate the outlet port from the inlet port and to separate incoming substances from outgoing substances. The pump draws and delivers substances by movement of the displacement ring within the pump chamber. When the pump chamber is sealed, ring oscillation creates a vacuum on the inlet port and pressure on the outlet port. The vacuum draws substances into the pump chamber through the inlet port while driving substances out of pump chamber through the outlet port. 
     In one embodiment, a crankshaft rotatably disposed within the pump housing drives ring oscillation. In this embodiment, the crankshaft comprises an input shaft and an offset shaft whereby rotation of input shaft rotates the offset shaft. The offset shaft is located inside the pump chamber and is encircled by the ring. A spacer, such as a bearing, is set on the offset shaft and rolls inside the ring as the crankshaft rotates. The diameter of the spacer and the width of the ring sidewall is chosen such that there is minimal clearance between the ring and the spacer and between the ring and the chamber sidewall. 
     In another embodiment, the housing can form a pump face, which opens into the pump chamber. A cover plate can attach to the housing to cover the pump face and to form an airtight seal with the pump chamber. The cover plate can attach to the housing, by attaching means including, but not limited to, bolts and screws. 
     In one embodiment, the pump can comprise a valve that has an anchored end and a free end. The anchored end can be pivotally attached to the pump chamber&#39;s inside wall at a position between the inlet port and the outlet port. The free end extends toward the pump chamber&#39;s centre. The valve can pivot into a recess in the pump chamber&#39;s inside wall in order to make the valve flush with the inside wall surface. During pumping, the valve free end contacts the ring and follows the ring&#39;s oscillating movement as the pump is operating. In response to ring contact, the free end is cyclically pushed into the recess until the pushing force from the oscillating ring has passed. The ring and the valve separate the inlet port from the outlet port. The valve can be of various types or styles, including but not limited to a flapper valve, a sliding valve, a wedge valve, a reed valve and a rocking valve. 
     In another embodiment, the pump can comprise a slider valve slidably disposed in the housing between the inlet port and the outlet port to separate and isolate the two ports from each other. The slider valve can further comprise a bias mechanism to urge the slider valve into the pump chamber and contact the ring and follow the ring&#39;s oscillating movement as the pump is operating. In other embodiments, the pump can further comprise a shoe disposed between the slider valve and the ring that can be configured to match the curvature of the ring and to move as the ring oscillates. 
     In another embodiment, the pump can include adjustable internal by-pass protection means to prevent over-pressuring and to control the output pressure of substances being pumped. The by-pass protection means can comprise, but is not limited to: (a) a check valve, a needle valve or a poppet valve located in a passageway connecting the outlet port to the inlet port, or (b) a spring mounted directly on the offset shaft to limit the pressure applied to ring against the internal wall of the pump chamber allowing substances to by-pass internally in the pump chamber past the ring. In another embodiment, the passageway valve can be controlled by a spring-loaded mechanism, such as a thumbscrew or other suitable means, to adjust and set the pressure at which the valve will open. 
     The pump on/off means can include, but is not limited to, an electric clutch or a mechanically engaging a gear or shaft operatively coupled to the crankshaft. 
     In one embodiment, the pump can provide both positive and variable displacement, wherein the volume of substances displaced by the pump can be varied, by increasing or decreasing ring diameter without affecting ring thickness or any other pump dimensions. The volume displaced by the pump is calculable and, therefore, the ring dimensions required for delivering an exact volume per revolution can also be calculated. The volume of substances displaced by the pump per crankshaft revolution is inversely proportional to the ring diameter. As the ring diameter is increased, the volume available for substances in the chamber decreases. 
     In another embodiment, the pump can be used with a ring of a customized size. Furthermore, the pump can be used with a kit, wherein the kit contains rings of differing diameters, allowing user to change the volume of substances displaced by the pump in order to provide the desired pumping rate. 
     In representative embodiments, the pump can have few moving parts to promote ease of repair. The pump can be designed with little friction loss in order to lengthen the duration of time the pump stays in calibration and to help ensure long, dependable substance delivery. To reduce wear and to help prevent unwanted or accidental adjustment, the pump can be internally adjustable and can have no exposed parts. 
     In a representative embodiment, the pump can have a simple design, which allows the pump: (a) to be manufactured at low cost, compared to other pumps in the field; (b) to be used for a variety of applications; and (c) to be made small and light relative to the substance it can inject. In other embodiments, the pump can be made mostly out of plastic for use in small, every day public applications such as soap injectors or agricultural chemical injectors. In further embodiments, the pump can be made with extreme precision with materials to be used in applications including but not limited to medicine, aerospace, or military applications. 
     Broadly stated, in some embodiments a pump is provided, comprising: a housing comprising an exterior surface and an enclosed interior chamber with a sidewall, the chamber substantially circular in cross-section; an inlet port providing communication between the exterior surface and the interior chamber; an outlet port providing communication between the exterior surface and the interior chamber; a crank assembly comprising a longitudinal axis rotatably disposed within said housing wherein the longitudinal axis is substantially coaxially aligned with the center of the circular cross-section of the interior chamber, the crank assembly configured for receiving input rotational power; a spacer support operatively connected to the crank assembly, the spacer support disposed within the interior chamber, the spacer support further comprising a spacer pin; an annular spacer rotatably disposed on the spacer pin; an annular ring disposed in the interior chamber, the annular ring further comprising a sidewall disposed between the annular spacer and the interior chamber sidewall, the width of the ring sidewall being substantially the same as the minimum distance separating the annular spacer and the interior chamber sidewall; and a slider valve slidably disposed in the housing, the slider valve configured to maintain contact with the ring as the crank assembly is rotating thereby substantially isolating the inlet port from the outlet port. 
     Broadly stated, in some embodiments a pump is provided, comprising: a housing comprising an exterior surface and an enclosed interior chamber with a sidewall, the chamber substantially circular in cross-section; an inlet port providing communication between the exterior surface and the interior chamber; an outlet port providing communication between the exterior surface and the interior chamber; a crankshaft comprising a longitudinal axis rotatably disposed within the housing wherein the longitudinal axis is substantially coaxially aligned with the center of the circular cross-section of the interior chamber, the crankshaft further configured for receiving input rotational power; an offset shaft having an axis disposed on the crankshaft wherein the offset shaft axis is offset and substantially parallel to the longitudinal axis whereby the offset shaft moves in a substantially circular path within the interior chamber when the crankshaft is rotating; an annular spacer rotatably disposed on the offset shaft; an annular ring disposed about the offset shaft, the annular ring having a sidewall disposed between the spacer and the interior chamber sidewall, the width of the ring sidewall being substantially the same as the minimum distance separating the spacer and the interior chamber sidewall; and a valve disposed between the inlet and outlet ports, the valve configured to maintain contact with the ring as the crankshaft is rotating thereby substantially isolating the inlet port from the outlet port. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front elevation cross-sectional view depicting a housing of one embodiment of an oscillating ring pump. 
         FIG. 2  is a front elevation cross-sectional view depicting one embodiment of an oscillating ring pump. 
         FIG. 3  is a side elevation cross-sectional exploded view depicting the pump of  FIG. 2 . 
         FIG. 4  is a front elevation cross-sectional view depicting a first alternate embodiment of an oscillating ring pump. 
         FIG. 5  is a front elevation cross-sectional view depicting a second alternate embodiment of an oscillating ring pump. 
         FIG. 6  is a front elevation cross-sectional view depicting a third alternate embodiment of an oscillating ring pump. 
         FIG. 7  a front elevation cross-sectional view depicting a fourth alternate embodiment of an oscillating ring pump. 
         FIG. 8  is a front elevation cross-sectional view depicting a fifth alternate embodiment of an oscillating ring pump. 
         FIG. 9  is a top cross-sectional plan view depicting a pressure relief/bypass valve on the ring pump of  FIG. 2 . 
         FIG. 10  is a front elevation cross-sectional view depicting the oscillating ring pump of  FIG. 2  with the ring located near top dead centre (“TDC”). 
         FIG. 11  is a front elevation view depicting the oscillating ring pump of  FIG. 2  with the ring rotated about 80° clockwise from TDC. 
         FIG. 12  is a front elevation view depicting the oscillating ring pump of  FIG. 2  with the ring rotated about 175° clockwise from TDC. 
         FIG. 13  is a front elevation view depicting the oscillating ring pump of  FIG. 2  with the ring rotated about 240° clockwise from TDC. 
         FIG. 14  is a front elevation view depicting the oscillating ring pump of  FIG. 2  with the ring rotated about 270° clockwise from TDC. 
         FIG. 15A  is a side elevation cross-sectional view depicting a sixth alternate embodiment of an oscillating ring pump. 
         FIG. 15B  is a side elevation cross-sectional view depicting a seventh alternate embodiment of an oscillating ring pump. 
         FIG. 16  is front elevation cross-sectional view depicting an alternate embodiment of the oscillating ring pump of  FIG. 7 . 
         FIG. 17  is an exploded perspective view, depicting the oscillating ring pump of  FIG. 16 . 
         FIG. 18  is an exploded perspective view depicting the crankshaft of the oscillating ring pump of  FIG. 17 . 
         FIG. 19  is a side elevation cross-sectional view depicting the crankshaft of  FIG. 18 . 
         FIG. 20  is a side cross-sectional view depicting the oscillating ring pump of  FIG. 16 . 
         FIG. 21  is a perspective view depicting the oscillating ring pump of  FIG. 16 . 
         FIG. 22  is a front elevation cross-sectional view depicting the proximity sensors of the oscillating ring pump of  FIG. 21 . 
         FIG. 23  is a front elevation cross-sectional view depicting the oscillating ring pump of  FIG. 16  with the ring located near TDC. 
         FIG. 24  is a front elevation cross-sectional view depicting the oscillating ring pump of  FIG. 16  with the ring rotated about 90° clockwise from TDC. 
         FIG. 25  is a front elevation cross-sectional view depicting the oscillating ring pump of  FIG. 16  with the ring rotated about 180° clockwise from TDC. 
         FIG. 26  is a front elevation cross-sectional view depicting the oscillating ring pump of  FIG. 16  with the ring rotated about 270° clockwise from TDC. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Shown in  FIG. 1  is a representative embodiment of housing  12  of pump  10 . Housing  12  comprises pump chamber  14  having sidewall  13 . In this embodiment, chamber  14  can be substantially circular in cross-section. Pump  10  comprises inlet and outlet ports  16  and  18  that provide communication between exterior side  11  of pump  10  and chamber  14 . Inlet port  16  terminates in chamber inlet  17  in chamber  14 . Outlet port  18  terminates in chamber outlet  19  in chamber  14 . In the illustrated embodiment, pump  10  can comprise flapper valve  22  that comprises fixed end  32  and free end  30 . Valve  22  can be pivotally attached to housing  12  at pivot point  34  between inlet port  16  and outlet port  18  thereby allowing valve free end  30  swing towards and away from the center of chamber  14 . Housing  12  can further comprise recess  15  whereby valve  22  can swing into recess  15  and be substantially flush with chamber sidewall  13 . 
     Referring to  FIG. 2 , an embodiment of pump  10  is shown with crankshaft  24  disposed at the center of chamber  14 . Crankshaft  24  has a longitudinal axis that is substantially perpendicular to chamber wall  7  and is coaxially aligned with the center of chamber  14 . Disposed on crankshaft  24  is offset shaft  26 . Offset shaft  26  has an axis that is offset and substantially parallel to the longitudinal axis of crankshaft  24  such that offset shaft  26  moves in a circular path within chamber  14  as crankshaft  24  rotates. Annular spacer  28  is placed on offset shaft  26  and can freely rotate about offset shaft  26 . In one embodiment, spacer  28  can comprise a roller bearing. In other embodiments, spacer  28  can comprise a needle bearing, a bushing or any other suitable bearing member that can rotate about offset shaft  26  as would be obvious to those skilled in the art. Disposed within chamber  14  is annular pump ring  20  such that it is placed about offset shaft  26 . Ring  20  comprises sidewall  21  that has a thickness that can be equal to or less than the minimum distance separating the outer edge of spacer  28  and chamber sidewall  13  whereby there is minimal clearance between spacer  28  and ring  20  and between ring  20  and sidewall  13 . In this manner, ring  20  can freely rotate or oscillate within chamber  14  as crankshaft  24  rotates yet maintain contact between spacer  28  and sidewall  13 . In another embodiment, ring sidewall  21  can have a rectangular cross-section to maximize the contact with spacer  28  and sidewall  13 . 
     Pump  10  can further comprise inlet check, valve  42  and outlet check valve  44 . Check valve  42  can include ball  46  and spring  50 . Spring  50  urges ball  46  to rest on valve seat  48  thereby sealing off inlet port  16 . Check valve  42  acts to prevent substances from prematurely entering chamber  14 . The spring constant of spring  50  determines the required pressure to lift ball  46  off of valve seat  48  and allow substances to enter chamber  14 . Similarly, check valve  44  acts to prevent substances from prematurely exiting chamber  14 . The spring constant of spring  56  determines the required pressure to lift ball  52  off of valve seat  54  and allow substances to exit chamber  14 . In representative embodiment, check valve  42  can be configured with a release pressure of approximately 2 p.s.i. whereas check valve  44  can be configured with a release pressure of approximately 10 p.s.i. 
     In further embodiments, housing  12  can comprise o-ring groove  8  and boltholes  6 . An o-ring seal can be placed in groove  8  to provide a seal between housing  12  and a cover (not shown) that can be bolted to housing  12  using bolts engaging boltholes  6 . 
     In operation, ring  20  can be an oscillating variable displacement ring. The movement of ring  20  pumps substances in and out of chamber  14  via inlet port  16  and outlet port  18 , respectively. Crankshaft  24  rotates to move offset shaft  26  in a circular path. Rotation of offset shaft  26  causes ring  20  to oscillate within chamber  14 . Oscillation of ring  20  creates vacuum pressure on inlet port  16  to draw substances into pump chamber  14 . The vacuum pressure is greater than the release pressure of check valve  42  thereby allowing substances to enter chamber  14  via chamber inlet  17 . As ring  20  moves within chamber  14 , substances are pushed towards chamber outlet  19  and check valve  44 . The pressure on the substances being pumped will exceed the release pressure of check valve  44  and allow substances to then exit via outlet port  18 . All the while, the pressure of the substances in chamber  14  will urge free end  30  of flapper valve  22  to maintain contact with ring  20  so as to provide a barrier that prevents substances from moving towards chamber inlet  17 . 
     By maintaining contact with ring  20 , free end  30  can be pushed into recess  15  by the movement of ring  20  until ring  20  has cyclically moved past recess  15 . Fixed end  32  is positioned on sidewall  13  such that flapper valve  22  covers chamber outlet  19  when pushed into recess  15  by ring  20  thereby closing off chamber outlet  19 . 
     Referring to  FIG. 3 , an exploded side view of pump  10  is shown. In this embodiment, crankshaft  24  can be operatively coupled to input shaft  29  that passes through opening  27  in housing  12  and can be supported by a pair of bearings  31 . Bearings  31  can be of the tapered roller variety or any other suitable replacement such as ball bearing, needle bearing, bushing or any other bearing as well known to those skilled in the art. Pump  10  can further include seal  25  disposed around crankshaft  24  to seal off chamber  14 . When assembled, spacer  28  is set upon offset shaft  26  and ring  20  is set upon spacer  28 . O-ring  9  can be placed in groove  8 . Cover  33  is placed against o-ring  9  on housing  12  to enclose and seal chamber  14 . Cover  33  can be secured into position with retainer ring  35  fastened to housing  12  by bolts  5  threaded into boltholes  6 . Cover  33  can be made of any suitable material that can withstand the pressure of substances being delivered by pump  10 . In a representative embodiment, cover  33  can be made of transparent Plexiglas of suitable thickness so as to enable visual inspection of pump  10  when in operation. 
     Referring to  FIG. 4 , another embodiment of pump  10  is shown. In this embodiment, flapper valve  22  can further include reed valve  36 . Reed valve  36  has fixed end  40  and free end  38 . Reed valve  36  can be positioned between flapper valve  22  and ring  20 . Reed valve  36  can be made of flexible material, such as spring steel or other suitable materials as known to those skilled in the art. The inclusion of reed valve  36  can enhance the seal made by flapper valve  22  when it contacts ring  20 . 
     In another embodiment, pump  10  can include biasing means to urge flapper valve  22  to contact ring  20 . In one embodiment, the biasing means can comprise spring  23  or it can be any other suitable mechanism as known to those skilled in the art. 
     Referring to  FIG. 5 , another embodiment of pump  10  is shown. In this embodiment, pump  10  can use wedge  58  as a valve as described above. Wedge  58  has fixed end  62  that is pivotally attached to housing  12  at pivot point  64  and free end  60  that contacts ring  20 . In this embodiment, spring  66  urges wedge  58  towards ring  20 . Spring  66  is secured in place by spring sleeve  68  and bolt  70  threaded into opening  74  in housing  12 . Shim  72  can be placed between spring  66  and bolt  70 . Shim  72  can be varied in thickness to vary the pre-load tension on spring  66 , that is, thinner shims will reduce the tension whereas thicker shims will increase the tension. 
     Referring to  FIG. 6 , another embodiment of pump  10  is shown. In this embodiment, slider valve  76  can be used to separate or isolate inlet  16  from outlet  18 . Slider valve  76  comprises valve face  77  that contacts ring  20 . Slider valve  76  is slidably disposed in valve guide opening  80  in housing  12  that is configured to receive slider valve  76 . Spring  78  can be disposed within opening  80  and valve  76  as illustrated to provide biasing means to urge slider valve  76  to the center of chamber  14  and to have slider valve face  77  maintain contact with ring  20 . In this embodiment, slider valve  76  can be configured to be substantially perpendicular to exterior surface  11  of housing  12 . 
     Referring to  FIG. 7 , another embodiment of pump  10  is shown. In this embodiment, pump  10  can have slider valve  82  slidably disposed in valve guide opening  90  disposed in housing  12  to receive slider valve  82 . Slider valve  82  can further comprise ball end  84  with valve shoe  86  rotatably coupled thereon. Shoe  86  can rotate on ball end  84  to maintain contact with ring  20  as ring  20  oscillates within chamber  14 . Spring  78  can be disposed within opening  90  and valve  82  as illustrated to provide biasing means to urge slider valve  82  to the center of chamber  14  and to have slider valve shoe  86  maintain contact with ring  20 . 
     Referring to  FIG. 8 , another embodiment of pump  10  is shown. In this embodiment, slider valve  92  and valve guide opening  94  disposed at an angle with respect to exterior surface  11  of housing  12 . In a representative embodiment, slider valve  92  and opening  94  are canted at an angle of approximately 10° off of vertical. In this embodiment, slider valve  92  can include opening  97  configured to receive valve shoe  98  that maintains contact with ring  20  as it rotates within chamber  14 . In this embodiment, shoe  98  can be semi-circular in cross-section and can have a concave contact surface for contacting ring  20 . Spring  96  can be disposed within opening  94  and valve  92  as illustrated to provide biasing means to urge slider valve  92  to the center of chamber  14  and to have slider valve shoe  98  maintain contact with ring  20 . 
     Referring to  FIG. 9 , another embodiment of pump  10  is shown. In this embodiment, pump  10  can comprise passageway  100  disposed in housing  12  to provide means for controlling the output pressure or amount of substances delivered by pump  10 . In the illustrated embodiment, housing  12  can comprise passageway  99  that provides communication between passageway  100  and the passageway that connects chamber outlet  19  to output port  18 . Passageway  99  can further comprise valve seat  108  for receiving ball valve  106 . Biasing means can be provided to urge ball valve  106  against valve seat  108  to close off passageway  99 . In the illustrated embodiment, the biasing means can include thumbscrew  104 , spring  110  and spring sleeve  112 . Spring  110  and spring sleeve  112  can be slidably disposed within opening  114  of thumbscrew  104 . The output pressure of substances delivered by pump  10  is dependent on the pressure required to lift ball valve  106  off of valve seat  108 . The more thumbscrew  104  is threaded into housing  12 , the more spring  110  is compressed to increase the pressure required to open ball valve  106 . The more thumbscrew  104  is threaded out of housing  12 , the less spring  110  is compressed thereby decreasing the pressure to open ball valve  106 . In a further embodiment, passageway  100  can comprise access port  101  and plug  102  to close off port  101  during operation of pump  10 . It should obvious to those skilled in the art that means other than a ball valve can be used to control the output pressure of substances delivered by pump  10  such as a needle valve as well as any other suitable means. 
     Referring to  FIGS. 10 to 14 , operation of an embodiment of pump  10  is illustrated. In  FIG. 10 , pump  10  is shown with ring  20  at approximately top dead center (“TDC”). For the purpose of these illustrations, substances are contained in pump chamber  14  in this initial condition. Pump  10  begins to operate when input rotational power is applied to crankshaft  24 . The input rotational power is applied to an input shaft (not shown) operatively attached to crankshaft  24 . The input rotational power can be obtained from any suitable source such as a motor or from rotating shafts that are operatively coupled to the input shaft, either by meshed gears, a belt and pulleys, a chain and sprockets or any other suitable means as well known to those skilled in the art. In the illustrated embodiment, crankshaft  24  can rotate clockwise as shown in chamber  14  thereby allowing flapper valve  22  to move away from recess  15 . It should be obvious to one skilled in the art, however, that pump  10  can be assembled in a mirrored configuration whereupon crankshaft  24  can rotate in a counter clockwise direction. 
     Referring to  FIG. 11 , ring  20  is at approximately 80° rotated from TDC. In this position, flapper valve  22  has moved away from recess  15  to expose chamber outlet  19 . Substances in pump chamber  14  are forced through chamber outlet  19  and exit through check valve  44  and output port  18 . As ring  20  rotates clockwise, pump chamber inlet side  14   a  is formed and begins to create a vacuum to draw in substances through inlet port  16 , check valve  42  and chamber inlet  17 . 
     Referring to  FIG. 12 , pump ring  20  is shown at approximately 175° rotated from TDC. In this position, pump chamber inlet side  14   a  is approximately the same volume as pump chamber outlet side  14   b . As ring  20  rotates clockwise, the volume of pump chamber outlet side  14   b  decreases thereby forcing substances through chamber outlet  19  to exit through check valve  44  and outlet port  18 . Flapper valve  22  acts as a barrier between pump chamber outlet side  14   b  and pump chamber inlet side  14   a . As crankshaft  24  continues to rotate clockwise, pump chamber inlet side  14   a  increases in volume thereby drawing in more substances in through chamber inlet  17 . 
     Referring to  FIG. 13 , pump ring  20  is shown at approximately 240° rotated from TDC. In this position, the volume of pump chamber outlet side  14   b  has decreased and flapper valve  22  has begun to retreat back into recess  15  to close off chamber outlet  19 . The volume of pump chamber inlet side  14   a  continues to increase to draw in more substances through chamber inlet  17 . 
     Referring to  FIG. 14 , pump ring  20  is shown at approximately 270° rotated from TDC whereby the volume of pump chamber outlet side  14   b  has been decreased to nearly zero. Flapper valve  22  is almost fully retracted into recess  15  to close off chamber outlet  19 . As pump ring  20  continues to move clockwise to TDC, the pumping process continues in the manner described whereby substances are drawn into and pumped out of pump chamber  14  simultaneously with each revolution of crankshaft  24 . The volume of substances displaced by pump  10  in each revolution of crankshaft  24  is a function of the diameter of ring  20 . As the diameter of ring  20  is increased, the amounts of substances drawn in and expelled by pump  10  decreases as the available volume for pump chamber inlet and outlet sides  14   a  and  14   b  has decreased. Similarly, as the diameter of ring  20  is decreased, the amounts of substances drawn in and expelled by pump  10  increases as the available volume for pump chamber inlet and outlet sides  14   a  and  14   b  has increased. 
     In another embodiment of pump  10 , pump  10  can be provided with a kit having a multiple number of rings  20  in various diameters but all having sidewall  21  of the same thickness. In this fashion, pump  10  can be easily configured to change the amount of substances it can displace or deliver simply by changing ring  20  of one diameter for another ring  20  having a different diameter. In this regard, a pump having variable displacement can be provided. 
     Referring to  FIG. 15A , a side view of pump  10  is shown. In this embodiment, crankshaft  24  can be operatively coupled to input shaft  29  that passes through opening  27  in housing  12  and can be supported by a pair of bearings  31 . Disposed on the end of offset shaft  26  is opening  128  that can receive offset shaft  126  disposed on crankshaft  120 . Crankshaft  120  can be rotatably disposed within housing cover  116  that can be, in turn, fastened to housing  12  using bolts, screws or any other suitable means. O-ring  7  can be placed between housing  12  and housing cover  116  to seal off chamber  14 . Crankshaft  12  can be operatively coupled to output shaft  122  which can be supported in shaft opening  118  of housing cover  116  by bearings  124 . Bearings  31  and  124  can be of the tapered roller variety or any other suitable replacement such as ball bearing, needle bearing, bushing or any other bearing as well known to those skilled in the art. Output shaft  122  can be used in any number of ways to provide rotational power to other devices. In one embodiment, one or more pumps  10  can be connected in tandem whereby the input shaft of one pump  10  is operatively coupled to the output shaft of a previous pump  10 . In this fashion, different substances can be pumped simultaneously at the same, one substance per pump in the tandem. 
     Referring to  FIG. 15B , another embodiment of pump  10  is shown. In some embodiments, pump  10  can comprise two or more chambers stacked end-to-end. In the illustrated embodiment, pump  10  can comprise chambers  14  and  130  separated by adaptor plate  136 , which can further comprise crankshaft extension adaptor  146  rotatably disposed in an opening disposed therein. Ring  20  and the inlet and outlet check valves are not shown in the figure to simplify the description of this embodiment of pump  10  but would otherwise be included in a working version of this embodiment. Offset shaft  126  can be operatively coupled to adaptor  146 . Offset shaft  126  can be rotatably disposed in opening  128  disposed in offset shaft  26 . Chamber  130  can be defined by housing  138  operatively coupled to adaptor plate  136 , and end cover plate  150  operatively coupled to housing  138 . In some embodiments, extension adaptor  146  can comprise extension offset shaft  148  extending into chamber  130 . Offset shaft  148  can further comprise coupler  140  extending therefrom to operatively couple crankshaft end support ring  144 . Support ring  144  can be disposed in recess  152  disposed in end cover plate  150 . In some embodiments, end cover plate  150  can further comprise end support bearing  142  disposed on protrusion  154  extending from end cover plate  150  in recess  152 . In operation, crankshaft  24  rotates thereby causing offset shaft  26  to rotate within chamber  14 . This can cause adaptor  146  to rotate and, hence, offset shaft  148  to rotate in chamber  130 . The coupling of offset shaft  148  to end support ring  144  via coupler  140  can support the rotation of offset shaft  148  in chamber  130  as support ring  144  rotates on bearing  142 . When rings  20  are placed on offset shafts  26  and  148  in chambers  14  and  130 , respectively, substances being pumped in chamber  14  can exit through outlet port  132  whereas substances being pumped in chamber  130  can exit through outlet port  134 . It is obvious to those skilled in the art that pump  10  as illustrated can be adapted to have multiple chambers or pump stages stacked end-to-end. 
     In another embodiment, two or more pumps can be connected in tandem to pump the same substance thereby increasing the amount of substances that can be delivered per revolution of the pump crankshafts. 
     In a further embodiment, an input manifold, as well known to those skilled in the art, can be used to collectively feed the input ports of the tandem-connected pumps from a single source of substances. 
     In yet another embodiment, an output manifold can be used to connect the output ports of the tandem-connected pumps to a single output whereby all of the pumped substances are delivered from a single output port. 
     In yet a further embodiment, the offset shafts of the tandem-connected pumps can be rotationally spaced apart from one another with respect to the longitudinal axis of the crankshafts. For example, in a two tandem pump configuration, the offset shafts can be spaced approximately 180° apart. For a three tandem pump configuration, the offset shafts can be spaced approximately 120° apart, and so on. By configuring the offset shafts in this manner, especially when using an output manifold, the pulsing of delivered substances that naturally occurs with a single pump can be reduced or smoothed out in the delivery of substances exiting the output manifold. 
     Referring to  FIG. 16 , another embodiment of pump  10  is shown. This embodiment is similar to the embodiment shown in  FIG. 7  except that inlet  16  and outlet  18  converge to form valve chamber  47 . In this  FIG. 16 , inlet  16  and outlet  18  are shown without check valves installed. It is obvious to those skilled in the art that check valves as shown  FIG. 7 , or their functional equivalents, can be installed in inlet  16  and outlet  18  to enable the functioning of pump  10 . 
     In some embodiments, pump  10  can comprise slider valve  82  slidably disposed in a valve guide opening disposed in housing  12  to receive slider valve  82 . Slider valve  82  can further comprise ball end  84  with valve shoe  86  rotatably coupled thereon. The combination of slider valve  82  and valve shoe  86  can extend through valve chamber  47  to contact ring  20  thereby separating and isolating inlet  16  from outlet  18 . Shoe  86  can rotate on ball end  84  to maintain contact with ring  20  as ring  20  oscillates within chamber  14 . Spring  78  can be disposed within slider valve  82  as illustrated to provide biasing means to urge slider valve  82  to the center of chamber  14  and to have slider valve shoe  86  maintain contact with ring  20 . Bolt  2  can thread into the valve guide opening to adjust the bias on spring  78 . Locknut  4  can be disposed on bolt  2  to tighten against housing  12  to keep bolt  2  in position once the desired bias on slider valve  82  has been set. Bolt  2  can further comprise o-ring  3  disposed therearound in the valve guide opening as means to prevent substances being pumped through pump  10  by escaping through the valve guide opening. In some embodiments, spacer  28  can comprise a bearing to, contact ring  20  and bias ring  20  towards sidewall  13  of chamber  14 . In some embodiments, spacer  28  can be disposed on sliding support  107 , which can be disposed between a pair of support guides  111  that limit the motion of sliding support  107  to that of a linear motion in the channel defined by offset faces  114  and guides  111 . 
     Referring to  FIG. 17 , an exploded view of pump  10  is shown. In some embodiments, crank assembly  55  can comprise crankshaft  24 , sliding support  107 , guides  111  and spacer  28 . Crank assembly  55  can pass through bearing spacer  1 , bearing  31  and seal assembly  25  through chamber  14  of housing  12  to pass through another bearing  31  and pulser ring  37 , which is held in position on crankshaft  24  by locknuts  5 . When assembled, ring  37  is disposed within bracket housing  39  whereby ring  37  can rotate therein in proximity to proximity sensors  41  mounted on bracket housing  39 . Proximity sensors  41  can comprise rotation detection means as well known to those skilled in the art to determine direction and rate of rotation of crankshaft  24 . Once crank assembly  55  is disposed within housing  12 , with ring  20  disposed within chamber  14 , chamber  14  can be enclosed by pump cover  33  attached to housing face  49  of housing  12 . Cover  33  can further comprise o-ring  9  placed in a groove disposed thereon to provide sealing means between cover  33  and housing face  49  to keep substances being pumped by pump  10  in chamber  14 . 
     Referring to  FIGS. 18 to 20 , one embodiment of crank assembly  55  is illustrated. In some embodiments, crank assembly  55  can comprise crankshaft  24  having longitudinal opening  95  extending partially into crankshaft  24  from one end. Spring rod  103  can be inserted into opening  95 , which can be further affixed to crankshaft  24  by rod end  121  being firmly seated in opening  123  disposed therein. In this configuration, spring rod  103  can be comprised of metal or other functionally equivalent material as well known to those skilled in the art such that spring rod  103  can function or operate as a cantilever spring. 
     In some embodiments, spring rod  103  can further comprise end  93  that can be configured to engage opening  119  disposed on sliding support  107 . In some embodiments, sliding support  107  can comprise two halves that can be assembled together with fasteners  109  to support spacer pin  105  disposed between the two halves that can further comprise spacer  28  rotatably disposed thereon. It is obvious to those skilled in the art that sliding support  107  can be comprised of a singular or integral member configured to support spacer pin  105 . When spring rod  103  is disposed within opening  95  and sliding support  107  is disposed on end  93 , sliding support  107  can move linearly in channel  91  formed by offset faces  114  disposed on the end of crankshaft  24 . In some embodiments, offset support guides  111  can be attached to offset faces  114  with dowel pins  112  extending into dowel holes  117  and fasteners  113  threaded into threaded openings  115  to further define channel  91 . When crank assembly  55  is assembled and inserted into chamber  14  with ring  20 , spring rod  103  can act as a bias mechanism to apply force to sliding support  107  and spacer  28  to bias or urge ring  20  towards sidewall  13 . This can be seen in  FIG. 20 . The physical dimensions of slider support  107 , spacer  28  and ring  20  can be selected such that spring rod  103  is deflected when these elements are disposed in chamber  14 . In so doing, spring rod  103  can apply force via sliding support  107  and spacer  28  to ring  20  to maintain contact with sidewall  13  as pump  10  is operating. 
     In some embodiments, these elements can also function as a built-in pressure relief valve for pump  10 . If the pressure of substances being pumped by pump  10  exceeds the pressure exerted on ring  20  by spring rod  103 , spring rod  103  can then deflect such that ring  20  can move away from sidewall  13  thereby allowing the pressure of the pumped substances to equalize throughout chamber  14 . 
     Referring to  FIG. 21 , a perspective view of pump  10  is shown. In this embodiment, pump  10  can comprise bracket housing  39  disposed on one thereof, bracket housing  39  further comprising a plurality of proximity sensors  41 . In the illustrated embodiment, four proximity sensors  41  are shown although it is obvious to those skilled in the art that fewer or more proximity sensors  41  can be disposed on bracket housing  39 . 
     Referring to  FIG. 22 , a cross-sectional view of bracket housing  39  is shown. In this embodiment, ring gear  37  (as attached to crankshaft  24  and as shown in  FIG. 20 ) is shown disposed within bracket housing  39 , ring gear  37  configured to rotate within bracket housing  39  as crankshaft  24  rotates. In some embodiments, ring gear  37  can comprise a plurality of ring gear teeth  51  that can operate in conjunction with proximity sensors  41  wherein a general purpose computer, a microprocessor, a microcontroller or other functionally equivalent as well known to those skilled in the art (not shown) operatively connected to proximity sensors  41  can determine the direction of rotation and rate of rotation of crankshaft  24  when pump  10  is operating. The information concerning the direction and rate of rotation can be used by those skilled in the art to determine the volume of substances being pumped through pump  10  having consideration to the physical dimensions and parameters of pump  10  including, but not limited to, the volume of chamber  14  and the size of ring  20 . 
     Referring to  FIGS. 23 to 26 , operation of the embodiment of pump  10  shown in  FIG. 16  is illustrated. For simplicity, these figures do not show include the check valves that would normally be disposed in inlet  16  and outlet  18 . The operation of this embodiment of pump  10  is similar to other embodiments of pump  10 , as described in detail above and as shown in the attached figures, save for the differences as discussed below. 
     In  FIG. 23 , pump  10  is shown with ring  20  at approximately TDC. In this position, ring  20  has compressed slider valve  82  upwards and sealed off valve chamber  47  wherein no substances can enter chamber  14  through inlet  16 , or exit chamber  14  through outlet  18 . For the purpose of these illustrations, substances are contained in pump chamber  14  in this initial condition. Pump  10  begins to operate when input rotational power is applied to crankshaft  24 . The input rotational power is applied to an input shaft (not shown) operatively attached to crankshaft  24 . The input rotational power can be obtained from any suitable source such as a motor or from rotating shafts that are operatively coupled to the input shaft, either by meshed gears, a belt and pulleys, a chain and sprockets or any other suitable means as well known to those skilled in the art. In the illustrated embodiment, crankshaft  24  can rotate clockwise as shown in chamber  14  thereby allowing slider valve  82  to move downward in valve chamber  47  and to open a communication path between chamber  14  and outlet  18 . It should be obvious to one skilled in the art, however, that pump  10  can be assembled in a mirrored configuration whereupon crankshaft  24  can rotate in a counter clockwise direction. 
     Referring to  FIG. 24 , ring  20  is shown at approximately 90° rotated clockwise from TDC. In so doing, the movement of ring  20  divides chamber  14  into two parts: chamber  14   a , which is formed between inlet  16  and where ring  20  contacts sidewall  13 ; and chamber  14   b , which is formed between outlet  18  and where ring  20  contacts sidewall  13 . In this position, ring  20  has moved away from valve chamber  47  and slider valve  82  has extended down somewhat to open a communication path between inlet  16  and chamber  14   a , and a communication path between outlet  18  and chamber  14   b . Slider valve  82  acts as a barrier between chambers  14   a  and  14   b  and to separate and isolate inlet  16  from outlet  18 . Substances in chamber  14   b  are moved towards outlet  18  as ring  20  rotates clockwise, as shown in the figure, while simultaneously drawing in substances into chamber  14   a  through inlet  16  due the vacuum or negative pressure that forms within chamber  14   a  as it increases in volume when ring  20  rotates from TDC. 
     Referring to  FIG. 25 , pump ring  20  is shown at approximately 180° rotated from TDC. In this position, pump chamber inlet side  14   a  is approximately the same volume as pump chamber outlet side  14   b . As ring  20  continues to rotate clockwise, the volume of pump chamber outlet side  14   b  decreases thereby forcing substances through outlet port  18 . Slider valve  82  and valve shoe  86  act as a barrier between chamber  14   a  and chamber  14   b . As crankshaft  24  continues to rotate clockwise, pump chamber inlet side  14   a  increases in volume thereby drawing in more substances in through inlet  16 . 
     Referring to  FIG. 26 , pump ring  20  is shown at approximately 270° rotated clockwise from TDC. In this position, the volume of chamber  14   b  has decreased and slider valve  22  has begun to retreat back into valve chamber  47 . The volume of chamber  14   a  continues to increase to draw in more substances through chamber inlet  16 . 
     As pump ring  20  continues to move clockwise back to TDC, the pumping process continues in the manner described whereby substances are drawn into and pumped out of pump chamber  14  simultaneously with each revolution of crankshaft  24 . The volume of substances displaced by pump  10  in each revolution of crankshaft  24  is a function of the diameter of ring  20 . As the diameter of ring  20  is increased, the amounts of substances drawn in and expelled by pump  10  decreases as the available volume chambers  14   a  and  14   b  has decreased. Similarly, as the diameter of ring  20  is decreased, the amounts of substances drawn in and expelled by pump  10  increases as the available volume for chambers  14   a  and  14   b  has increased. 
     Although a few embodiments have been shown and described, it will be appreciated by those skilled in the art that various changes and modifications might be made without departing from the scope of the invention. The terms and expressions used in the preceding specification have been used herein as terms of description and not of limitation, and there is no intention in the use of such terms and expressions of excluding equivalents of the features shown and described or portions thereof, it being recognized that the scope of the invention is defined and limited only by the claims that follow.