Abstract:
A transmissionless variable output pumping unit comprising a multiple crankshaft pump driven by a prime mover. The apparatus includes an adjustment mechanism for adjusting a phase angle between first and second crankshafts. Plungers in the pump are disposed in cylinders forming part of a pumping chamber. When the phase angle is at a minimum, the plungers operate together for maximum discharge from the pump. When the phase angle is at a maximum, the plungers operate substantially opposite one another for zero discharge. The phase angle may be infinitely adjusted between the minimum and maximum.

Description:
BACKGROUND  
         [0001]    This invention relates to reciprocating pumping units, and more particularly, a pumping unit having variable output without using a transmission between the pump and the prime mover therefor.  
           [0002]    Reciprocating pumping units are well known, and such units have been used extensively in oil field applications, such as for pumping water into and out of the wells. Reciprocating pumps are known as fixed or positive displacement pumps.  
           [0003]    Prime mover power sources for these pumps are typically diesel engines, but other devices may be used. Multi-ratio automatic transmissions are typically used to drive the pumps to achieve a finite selection of flow rates or pumping rates. Minor flow rate “rangeability” is enabled within any given gear in the transmission by varying the engine speed, but this often requires the engine to operate at less than its maximum horsepower capability which is obviously inefficient. Further, such pumping unit configurations cannot begin pumping at full engine speed, because they are not capable of withstanding the sudden stress on engaging the transmission at full engine speed. Instead, the transmission is shifted into the selected gear while the engine is at low speed, and the pump is at rest. The gear range is selected based on the desired initial pump discharge rate. After engaging the transmission, the engine speed is increased, thus transferring power through the torque converter in the transmission. Only then can the engine speed be increased to the engine&#39;s maximum horsepower rating. Once pumping has thus commenced, the transmissions may be shifted “on-the-fly” to achieve various discharge flow rates in an attempt to keep the engine operating near its peak power speed.  
           [0004]    Such pumping unit designs do not provide infinitely variable discharge rates at full horsepower, and there is a need for a pumping unit which does provide this feature. A further problem with the prior art pumping units is that, as power requirements increase, the reliability of existing transmissions has proven to decrease to an unacceptable level.  
           [0005]    The present invention solves these problems by providing a variable displacement pumping machine consisting of a multiple-crankshaft pump driven by a rotational power source which is enabled to operate at a constant speed if desired and thus take full advantage of the full power of the power source at any given discharge flow rate.  
         SUMMARY  
         [0006]    The transmissionless variable output pumping unit of the present invention comprises a multiple crankshaft pump and a rotational prime mover or power source to drive the pump. The pumping unit can operate at a constant speed so that it can take advantage of the full power output of the prime mover at any particular discharge flow rate selected for the pump. The prime mover may be operated at various speeds depending on the desire output horsepower.  
           [0007]    Rotational power is transmitted from the prime mover or movers through a synchronizing mechanism, and individual drive trains are coupled to each pump crankshaft. The individual drive systems are configured to cause the pump crankshafts to rotate at the same speed either in the same or opposite directions. The drive systems are positively synchronized in at least one position along the drive train. One or more of the individual drive trains comprises at least one planetary speed reducer. At least one of these planetary speed reducers is mounted such that it allows the traditionally stationary portion of its gearing to be rotated via a positioning mechanism to impart a phase lead or lag in its associated drive train. The traditionally stationary portion of the gear is typically the outer ring gear, but the invention is not intended to be so limited. The phase difference is used to alter the rotational relationship of the crankshafts in such a fashion as to increase or decrease the effective displacement of the pump.  
           [0008]    The invention may be described as a pumping apparatus comprising a first cylinder, a second cylinder, a first plunger reciprocably disposed in the first cylinder and adapted for pumping fluid from the first cylinder, a second plunger reciprocably disposed in the second cylinder and adapted for pumping fluid from the second cylinder, a first crankshaft connectable to a prime mover and connected to the first plunger, a second crankshaft connectable to the prime mover and connected to the second plunger, and an adjustment mechanism connected to at least one of the first and second crankshafts such that a phase angle between the first and second crankshafts may be adjusted.  
           [0009]    The phase angle may be adjusted between minimum and maximum phase angles corresponding to minimum and maximum pumping rates for the first and second plungers. Preferably, the phase angle may be infinitely adjusted between the minimum and maximum phase angles. The minimum phase angle is zero, and the maximum phase angle may be 180 degrees.  
           [0010]    In one embodiment of the invention, the first and second cylinders are coaxial and have substantially the same diameter. In another embodiment, the first and second cylinders are angularly disposed to one another, such as at 90 degrees.  
           [0011]    The apparatus further comprises a drive train connecting the first and second crankshafts to the prime mover. In a preferred embodiment, this drive train comprises a first drive shaft driven by the prime mover, a second drive shaft driven by the prime mover, a first gear train connected between the first drive shaft and the first crankshaft, and a second gear train connected between the second drive shaft and the second crankshaft. The first gear train is a planetary gear train having a fixed first outer housing, the second gear train is a planetary gear train having a second outer housing, and the adjustment mechanism further comprises an angular adjustment for the second outer housing corresponding to the phase angle.  
           [0012]    One embodiment of the adjustment mechanism comprises a lever extending from the first outer housing. In another, the second outer housing has an outer geared surface, and the adjustment mechanism comprises a spur gear engaged with the outer geared surface. In a different drive train, the second outer housing has an outer geared surface, and the adjustment mechanism comprises a worm gear engaged with the outer geared surface.  
           [0013]    Numerous objects and advantages of the invention will become apparent when the following detailed description of the preferred embodiments is read in conjunction with the drawings illustrating such embodiments.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]    [0014]FIG. 1 shows a first embodiment of a transmissionless variable output pumping unit of the present invention having coaxial plungers in a maximum discharge configuration.  
         [0015]    [0015]FIG. 2 shows the first embodiment in a zero discharge configuration.  
         [0016]    [0016]FIG. 3 illustrates a second embodiment of the invention having plungers that are angularly disposed to one another.  
         [0017]    [0017]FIG. 4 shows a third embodiment of the invention having plungers that are angularly disposed and have a crossover position.  
         [0018]    [0018]FIG. 5 shows details of gear trains used to adjust the phase angle between crankshafts in any of the embodiments of the invention, including a manual adjustment mechanism.  
         [0019]    [0019]FIG. 6 is a detailed view of an adjustment mechanism having a spur gear drive.  
         [0020]    [0020]FIG. 7 is a detailed view of an adjustment mechanism having a worm gear drive.  
         [0021]    [0021]FIG. 8 shows details of one of the gear trains including a planet carrier. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
     First Embodiment  
       [0022]    Referring now to the drawings, and more particularly to FIGS. 1 and 2, a first embodiment of a transmissionless variable output pumping unit of the present invention is shown and generally designated by the numeral  10 . First embodiment pumping unit  10  comprises a first pumping section  12  and a second pumping section  14 . First and second pumping sections  12  and  14  are synchronized and driven by a gear train which will be subsequently described herein. First and second pumping sections  12  and  14  are positive displacement types. It should be understood that any of the pumping units described herein could have additional pumping sections, and the invention is not intended to be limited to those with two.  
         [0023]    First and second pumping sections  12  and  14  operatively engage a pump housing  16  having a first cylinder bore  18  and a second cylinder bore  20  therein. It will be seen that first and second cylinder bores  18  and  20  are coaxial in first embodiment pumping unit  10  and in communication with one another. First and second cylinder bores  18  and  20  form portions of a pumping chamber  22  within pump housing  16 . First and second cylinder bores  18  and  20  are also illustrated as having substantially the same diameter.  
         [0024]    Pump housing  16  has an inlet or suction port  24  and an outlet or discharge port  26  therein. An inlet or suction valve  28  is disposed in pump housing  16  such that it allows fluid to flow from inlet port  24  into pumping chamber  22  while preventing reverse flow. An outlet or discharge valve  30  is also disposed in pump housing  16 , and the discharge valve  30  allows fluid to flow from pumping chamber  22  into discharge port  26  while preventing reverse flow. Inlet valve  28  and discharge valve  30  are of a kind generally known in the art and allow fluid flow therethrough in only one direction. This flow of fluid through first embodiment pumping unit  10  will be further described herein.  
         [0025]    First pumping section  12  comprises a first piston or plunger  32  reciprocably disposed in first cylinder bore  18 . First plunger  32  is attached to a first connecting rod  34  which is in turn attached to a first crankshaft  36 . First crankshaft  36  is rotatably disposed in a first crankcase  38  which is attached to pump housing  16  adjacent to first cylinder bore  18 . The rotational mounting of first crankshaft  36  in first crankcase  38  is substantially known in the art.  
         [0026]    Similarly, second pumping section  14  comprises a second piston or plunger  40  reciprocably disposed in second cylinder bore  20 . Second plunger  40  is attached to a second connecting rod  42  which is in turn attached to a second crankshaft  44 . Second crankshaft  44  is rotatably disposed in a second crankcase  46  which is attached to pump housing  16  adjacent to second cylinder bore  20 . The rotational mounting of second crankshaft  44  in second crankcase  46  is substantially known in the art.  
         [0027]    Each of crankshafts  36  and  44  can have multiple plungers mounted thereon, not just the single ones illustrated. Also, crankshafts  36  and  44  can be rotated in opposite directions if desired.  
         [0028]    [0028]FIG. 1 illustrates first embodiment pumping unit  10  in a maximum pumping configuration wherein first and second pumping sections  12  and  14  operate in phase with one another. That is, in this maximum pumping configuration, first and second plungers  32  and  40  always move in opposite directions to one another. During a suction or intake cycle, first and second plungers  32  and  40  both move outwardly from pumping chamber  22 , and during a pumping or discharge cycle, the first and second plungers  32  and  40  both move inwardly toward the pumping chamber  22 . If first crankshaft  36  is rotated at an angle, Ø, from bottom dead center and second crankshaft  44  is rotated at an angle, β, from bottom dead center, then:  
         Ø=β 
         [0029]    With first embodiment pumping unit  10  in this maximum pumping configuration, fluid enters pumping chamber  22  through inlet valve  28 . When the pressure of fluid in pumping chamber  22  is less than the pressure in inlet port  24  less the pressure necessary to overcome the force of the springs in inlet valve  28 , inlet valve  28  will open and fluid will flow inwardly therethrough. Fluid will not flow backward through discharge valve  30 . When first and second plungers  32  and  40  reach the end of the suction stroke in which they are the maximum distance away from one another, they reverse direction and move toward each other to form the pumping cycle. When the pressure of fluid in pumping chamber  22  is greater than the pressure in discharge port  26  plus the pressure necessary to overcome the force of the springs in discharge valve  30 , discharge valve  30  will open and fluid will flow outwardly therethrough. Fluid will not flow backward through inlet valve  28 . It will be seen by those skilled in the art that this operation of first and second pumping sections  12  and  14  in phase with one another will produce the maximum flow of fluid through first embodiment pumping unit  10 .  
         [0030]    It should be noted that, while inlet valve  28  and discharge valve  30  are illustrated as spring-loaded plate valves, other types of known pump valves could be used. For example, reed valves could be incorporated. The invention is not intended to be limited to any particular valve construction.  
         [0031]    Referring now to FIG. 2, a zero discharge configuration of first embodiment pumping unit  10  is illustrated. In this zero pumping configuration, first and second pumping sections  12  and  14  operate 180 degrees out of phase with one another. That is, in this zero pumping configuration, first and second plungers  32  and  40  always move in the same direction as one another. During a first cycle, first and second plungers  32  and  40  both move to the right with respect to pumping chamber  22 , and during another pumping cycle, first and second plungers  32  and  40  both move to the left with respect to pumping chamber  22 . If first crankshaft  36  is rotated at an angle, Ø, from bottom dead center and second crankshaft  44  is rotated at an angle, β, from bottom dead center, then:  
         Ø=β−180° 
         [0032]    With first embodiment pumping unit  10  in this zero pumping configuration, substantially no fluid enters pumping chamber  22  through inlet valve  28  or is discharged therefrom through discharge valve  30 . It will be seen by those skilled in the art that the total volume of pumping chamber  22  does not change. The fluid in it is simply moved back and forth so that nothing changes and no fluid is pumped in or out. This assumes that any heating of the fluid by this movement and any related change in density of the fluid is insignificant.  
       Second Embodiment  
       [0033]    Referring now to FIG. 3, a second embodiment of the transmissionless variable output pumping unit of the present invention is shown and generally designated by the numeral  100 . Second embodiment pumping unit  100  comprises a first pumping section  112  and a second pumping section  114 . First and second pumping sections  112  and  114  are synchronized and driven by a gear train which will be subsequently described herein. First and second pumping sections  112  and  114  are positive displacement types.  
         [0034]    First and second pumping sections  112  and  114  operatively engage a pump housing  116  having a first cylinder bore  118  and a second cylinder bore  120  therein. In this second embodiment pumping unit  100 , first and second cylinder bores  118  and  120  are angularly disposed from one another and are in communication with one another. FIG. 3 illustrates this to be an angle of approximately 90 degrees, but the invention is not intended to be limited to any particular angle. First and second cylinder bores  118  and  120  form portions of a pumping chamber  122  within pump housing  116 . First and second cylinder bores  118  and  120  are also illustrated as having substantially the same diameter.  
         [0035]    Pump housing  116  has an inlet or suction port  124  and an outlet or discharge port  126  therein. An inlet or suction valve  128  is disposed in pump housing  116  such that it allows fluid to flow from inlet port  124  into pumping chamber  122  while preventing reverse flow. An outlet or discharge valve  130  is also disposed in pump housing  116 , and discharge valve  130  allows fluid to flow from pumping chamber  122  into discharge port  126  while preventing reverse flow. Inlet valve  128  and discharge valve  130  are of a kind generally known in the art and allow fluid flow therethrough in only one direction. This flow of fluid through second embodiment pumping unit  100  will be further described herein.  
         [0036]    First pumping section  112  comprises a first piston or plunger  132  reciprocably disposed in first cylinder bore  118 . First plunger  132  is attached to a first connecting rod  134  which is in turn attached to a first crankshaft  136 . First crankshaft  136  is rotatably disposed in a first crankcase  138  which is attached to pump housing  116  adjacent to first cylinder bore  118 . The rotational mounting of first crankshaft  136  in first crankcase  138  is substantially known in the art.  
         [0037]    Similarly, second pumping section  114  comprises a second piston or plunger  140  reciprocably disposed in second cylinder bore  120 . Second plunger  140  is attached to a second connecting rod  142  which is in turn attached to a second crankshaft  144 . Second crankshaft  144  is rotatably disposed in a second crankcase  146  which is attached to pump housing  116  adjacent to second cylinder bore  120 . The rotational mounting of second crankshaft  144  in second crankcase  146  is substantially known in the art.  
         [0038]    Each of crankshafts  136  and  144  can have multiple plungers mounted thereon, not just the single ones illustrated. Also, crankshafts  136  and  144  can be rotated in opposite directions if desired.  
         [0039]    [0039]FIG. 3 illustrates second embodiment pumping unit  100  in a maximum pumping configuration wherein first and second pumping sections  112  and  114  operate in phase with one another. That is, in this maximum pumping configuration, first and second plungers  132  and  140  always move in the same direction with respect to pumping chamber  122 . During a suction or intake cycle, first and second plungers  132  and  140  both move away from pumping chamber  122  toward a bottom dead center position, and during a pumping or discharge cycle, first and second plungers  132  and  140  both move toward pumping chamber  122  to a top dead center position. If first crankshaft  136  is rotated at an angle, Ø, from bottom dead center and second crankshaft  144  is rotated at an angle, β, from bottom dead center, then:  
         Ø=β 
         [0040]    With second embodiment pumping unit  100  in this maximum pumping configuration, fluid enters pumping chamber  122  through inlet valve  128 . When the pressure of fluid in pumping chamber  122  is less than the pressure in inlet port  124  less the pressure necessary to overcome the force of the springs in inlet valve  128 , inlet valve  128  will open and fluid will flow inwardly therethrough. Fluid will not flow backward through discharge valve  130 . When first and second plungers  132  and  140  reach the end of the suction stroke in which they are the maximum distance away from pumping chamber  122 , they reverse direction and move toward pumping chamber  122  to form the pumping cycle. When the pressure of fluid in pumping chamber  122  is greater than the pressure in discharge port  126  plus the pressure necessary to overcome the force of the springs in discharge valve  130 , discharge valve  130  will open and fluid will flow outwardly therethrough. Fluid will not flow backward through inlet valve  128 . It will be seen by those skilled in the art that this operation of first and second pumping sections  112  and  114  in phase with one another will produce the maximum flow of fluid through second embodiment pumping unit  100 .  
         [0041]    A zero discharge configuration of second embodiment pumping unit  100  is when first and second pumping sections  112  and  114  operate 180 degrees out of phase with one another. That is, in this zero pumping configuration, first and second plungers  132  and  140  always move in opposite directions with respect to pumping chamber  122 . During a first cycle, first plunger  132  moves toward pumping chamber  122  while second plunger  140  moves away from pumping chamber  122 . During a second pumping cycle, first plunger  132  moves away from pumping chamber  122 , and second plunger  140  moves toward pumping chambers  122 . If first crankshaft  136  is rotated at an angle, Ø, from bottom dead center and second crankshaft  144  is rotated at an angle, β, from bottom dead center, then:  
         Ø=β−180° 
         [0042]    With second embodiment pumping unit  100  in this zero pumping configuration, substantially no fluid enters pumping chamber  122  through inlet valve  128  or is discharged therefrom through discharge valve  130 . It will be seen by those skilled in the art that the total volume of pumping chamber  122  does not change. The fluid in it is simply moved back and forth so that nothing changes and no fluid is pumped in or out. This assumes that any heating of the fluid by this movement and any related change in density of the fluid is insignificant.  
       Third Embodiment  
       [0043]    Referring now to FIG. 4, a third embodiment of the transmissionless variable output pumping unit of the present invention is shown and generally designated by the numeral  150 . Third embodiment pumping unit  150  is similar to second embodiment pumping unit  100  in that the cylinders are angularly disposed from one another. The same reference numerals are used for similar components. In third embodiment pumping unit  150 , however, plunger  132  can cross over plunger  140  as shown. This minimizes the unswept volume in pumping chamber  122 .  
       Gear Train Detail  
       [0044]    [0044]FIGS. 5-7 show different embodiments of a gear drive train to operate pumping unit  10 ,  100  or  150 . Referring specifically to FIG. 5, one embodiment drive train  200  is shown. Drive train  200  may be used to drive any of the pumping unit embodiments previously described herein. As illustrated, drive train  200  is driven by a prime mover such as a diesel engine  202 , although other prime movers would also be acceptable. Diesel engine  202  has a dual power take-off  201  connected thereto so that rotational power is provided to a first drive shaft  204  and a second drive shaft  206 .  
         [0045]    A first planetary gear reducer or gear train  208  is connected to first drive shaft  204 . First planetary gear reducer  208  has a first outer housing  210  with a set of planetary gears  212 ,  214 , and  216  disposed therein and around a first sun gear  215  on an end of first drive shaft  204 . A first planet carrier  217  holds planetary gears,  212 ,  214 , and  216  in relationship to one another.  
         [0046]    Referring now to FIG. 8, details of first planet carrier  217  are shown. Planetary gears  212 ,  214 , and  216  have a planetary gear shaft  240 ,  242 , and  244  correspondingly extending therefrom. Planetary gear shafts  240 ,  242 , and  244  fit in openings  246 ,  248 , and  250 , respectively, in first planet carrier  217 . As first drive shaft  204  is driven by diesel engine  202 , first sun gear  215  engages and drives planetary gears  212 ,  214 , and  216  so that they orbit around first sun gear  215 . It will be seen by those skilled in the art that this causes corresponding rotation of first planet carrier  217 . First planet carrier  217  has a first output shaft  252  which is integral with or connected to first crankshaft  36  or  136 . A speed reducer (not shown) of a kind known in the art may be used between first output shaft  252  and first crankshaft  36  or  136  if desired.  
         [0047]    Similarly, a second planetary gear reducer or gear train  218  is connected to second drive shaft  206 . Second planetary gear reducer  218  has a second outer housing  220  with a set of planetary gears  222 ,  224 , and  226  disposed therein and around a second sun gear  225  on an end of second drive shaft  206 . A second planet carrier  227  holds planetary gears  222 ,  224 , and  226  in relationship to one another.  
         [0048]    Second planet carrier  227  is substantially identical to first planet carrier  217  previously described and shown in FIG. 8. Second planet carrier  227  has a second output shaft  254  that is integral with or connected to second crankshaft  44  or  144 . Again, a speed reducer (not shown) of a kind known in the art may be used between second output shaft  254  and second crankshaft  44  or  144  if desired.  
         [0049]    First outer housing  210  is fixed and cannot rotate. Second outer housing  220  is not fixed. It may be rotated about second drive shaft  206 . An adjustment mechanism  228  is used to rotate second outer housing  220  by an angle corresponding to the desired phase angle relationship between first and second pumping sections  12  and  14 , such as the maximum and zero pumping configurations previously described or anything in between. In the embodiment of FIG. 5, adjustment mechanism  228  is shown as a lever  230 . Lever  230  can be actuated by hand or by some other means, such as a pneumatic or hydraulic cylinder (not shown).  
         [0050]    Referring now to FIG. 6, a different adjustment mechanism  228 ′ is shown having a spur gear drive. In this embodiment, planetary gears  222 ,  224 , and  226  and second planet carrier  227  are the same as previously described. Planetary gears  222 ,  224 , and  226  are disposed around second sun gear  225  and within a second outer housing in the form of a first spur gear  232 . A second spur gear  234  is engaged with the geared surface of first spur gear  232  and is mounted on a gear shaft  236 . Gear shaft  236  can be driven by any means known in the art such as a rotary actuator, servo motor, etc.  
         [0051]    Referring now to FIG. 7, an additional adjustment mechanism  228 ″ is shown having a worm gear drive. In this embodiment, planetary gears  222 ,  224 , and  226  and second planet carrier  227  are the same as previously described. Planetary gears  222 ,  224 , and  226  are disposed around second sun gear  225  and within a second outer housing in the form of a first gear  256 . A worm gear  258  is engaged with the geared surface of first gear  256 . A worm gear shaft  260  extends from worm gear  258 . Worm gear shaft  260  can be driven by any means known in the art such as a rotary actuator, servo motor, etc.  
         [0052]    It will be seen, therefore, that the transmissionless variable output pumping unit of the present invention is well adapted to carry out the ends and advantages mentioned as well as those inherent therein. While several preferred embodiments have been shown for the purposes of this disclosure, numerous changes may be made by those skilled in the art. All such changes are encompassed with the scope and spirit of the appended claims.