Transmissionless variable output pumping unit

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.

BACKGROUND

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.

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.

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'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.

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.

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

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.

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.

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.

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.

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.

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.

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.

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.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

First Embodiment

Referring now to the drawings, and more particularly toFIGS. 1 and 2, a first embodiment of a transmissionless variable output pumping unit of the present invention is shown and generally designated by the numeral10. First embodiment pumping unit10comprises a first pumping section12and a second pumping section14. First and second pumping sections12and14are synchronized and driven by a gear train which will be subsequently described herein. First and second pumping sections12and14are 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.

First and second pumping sections12and14operatively engage a pump housing16having a first cylinder bore18and a second cylinder bore20therein. It will be seen that first and second cylinder bores18and20are coaxial in first embodiment pumping unit10and in communication with one another. First and second cylinder bores18and20form portions of a pumping chamber22within pump housing16. First and second cylinder bores18and20are also illustrated as having substantially the same diameter.

Pump housing16has an inlet or suction port24and an outlet or discharge port26therein. An inlet or suction valve28is disposed in pump housing16such that it allows fluid to flow from inlet port24into pumping chamber22while preventing reverse flow. An outlet or discharge valve30is also disposed in pump housing16, and the discharge valve30allows fluid to flow from pumping chamber22into discharge port26while preventing reverse flow. Inlet valve28and discharge valve30are 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 unit10will be further described herein.

First pumping section12comprises a first piston or plunger32reciprocably disposed in first cylinder bore18. First plunger32is attached to a first connecting rod34which is in turn attached to a first crankshaft36. First crankshaft36is rotatably disposed in a first crankcase38which is attached to pump housing16adjacent to first cylinder bore18. The rotational mounting of first crankshaft36in first crankcase38is substantially known in the art.

Similarly, second pumping section14comprises a second piston or plunger40reciprocably disposed in second cylinder bore20. Second plunger40is attached to a second connecting rod42which is in turn attached to a second crankshaft44. Second crankshaft44is rotatably disposed in a second crankcase46which is attached to pump housing16adjacent to second cylinder bore20. The rotational mounting of second crankshaft44in second crankcase46is substantially known in the art.

Each of crankshafts36and44can have multiple plungers mounted thereon, not just the single ones illustrated. Also, crankshafts36and44can be rotated in opposite directions if desired.

FIG. 1illustrates first embodiment pumping unit10in a maximum pumping configuration wherein first and second pumping sections12and14operate in phase with one another. That is, in this maximum pumping configuration, first and second plungers32and40always move in opposite directions to one another. During a suction or intake cycle, first and second plungers32and40both move outwardly from pumping chamber22, and during a pumping or discharge cycle, the first and second plungers32and40both move inwardly toward the pumping chamber22. If first crankshaft36is rotated at an angle, Ø, from bottom dead center and second crankshaft44is rotated at an angle, β, from bottom dead center, then:
Ø=β

With first embodiment pumping unit10in this maximum pumping configuration, fluid enters pumping chamber22through inlet valve28. When the pressure of fluid in pumping chamber22is less than the pressure in inlet port24less the pressure necessary to overcome the force of the springs in inlet valve28, inlet valve28will open and fluid will flow inwardly therethrough. Fluid will not flow backward through discharge valve30. When first and second plungers32and40reach 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 chamber22is greater than the pressure in discharge port26plus the pressure necessary to overcome the force of the springs in discharge valve30, discharge valve30will open and fluid will flow outwardly therethrough. Fluid will not flow backward through inlet valve28. It will be seen by those skilled in the art that this operation of first and second pumping sections12and14in phase with one another will produce the maximum flow of fluid through first embodiment pumping unit10.

It should be noted that, while inlet valve28and discharge valve30are 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.

Referring now toFIG. 2, a zero discharge configuration of first embodiment pumping unit10is illustrated. In this zero pumping configuration, first and second pumping sections12and14operate 180 degrees out of phase with one another. That is, in this zero pumping configuration, first and second plungers32and40always move in the same direction as one another. During a first cycle, first and second plungers32and40both move to the right with respect to pumping chamber22, and during another pumping cycle, first and second plungers32and40both move to the left with respect to pumping chamber22. If first crankshaft36is rotated at an angle, Ø, from bottom dead center and second crankshaft44is rotated at an angle, β, from bottom dead center, then:
Ø=β−180°

With first embodiment pumping unit10in this zero pumping configuration, substantially no fluid enters pumping chamber22through inlet valve28or is discharged therefrom through discharge valve30. It will be seen by those skilled in the art that the total volume of pumping chamber22does 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

Referring now toFIG. 3, a second embodiment of the transmissionless variable output pumping unit of the present invention is shown and generally designated by the numeral100. Second embodiment pumping unit100comprises a first pumping section112and a second pumping section114. First and second pumping sections112and114are synchronized and driven by a gear train which will be subsequently described herein. First and second pumping sections112and114are positive displacement types.

First and second pumping sections112and114operatively engage a pump housing116having a first cylinder bore118and a second cylinder bore120therein. In this second embodiment pumping unit100, first and second cylinder bores118and120are angularly disposed from one another and are in communication with one another.FIG. 3illustrates 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 bores118and120form portions of a pumping chamber122within pump housing116. First and second cylinder bores118and120are also illustrated as having substantially the same diameter.

Pump housing116has an inlet or suction port124and an outlet or discharge port126therein. An inlet or suction valve128is disposed in pump housing116such that it allows fluid to flow from inlet port124into pumping chamber122while preventing reverse flow. An outlet or discharge valve130is also disposed in pump housing116, and discharge valve130allows fluid to flow from pumping chamber122into discharge port126while preventing reverse flow. Inlet valve128and discharge valve130are 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 unit100will be further described herein.

First pumping section112comprises a first piston or plunger132reciprocably disposed in first cylinder bore118. First plunger132is attached to a first connecting rod134which is in turn attached to a first crankshaft136. First crankshaft136is rotatably disposed in a first crankcase138which is attached to pump housing116adjacent to first cylinder bore118. The rotational mounting of first crankshaft136in first crankcase138is substantially known in the art.

Similarly, second pumping section114comprises a second piston or plunger140reciprocably disposed in second cylinder bore120. Second plunger140is attached to a second connecting rod142which is in turn attached to a second crankshaft144. Second crankshaft144is rotatably disposed in a second crankcase146which is attached to pump housing116adjacent to second cylinder bore120. The rotational mounting of second crankshaft144in second crankcase146is substantially known in the art.

Each of crankshafts136and144can have multiple plungers mounted thereon, not just the single ones illustrated. Also, crankshafts136and144can be rotated in opposite directions if desired.

FIG. 3illustrates second embodiment pumping unit100in a maximum pumping configuration wherein first and second pumping sections112and114operate in phase with one another. That is, in this maximum pumping configuration, first and second plungers132and140always move in the same direction with respect to pumping chamber122. During a suction or intake cycle, first and second plungers132and140both move away from pumping chamber122toward a bottom dead center position, and during a pumping or discharge cycle, first and second plungers132and140both move toward pumping chamber122to a top dead center position. If first crankshaft136is rotated at an angle, Ø, from bottom dead center and second crankshaft144is rotated at an angle, β, from bottom dead center, then:
Ø=β

With second embodiment pumping unit100in this maximum pumping configuration, fluid enters pumping chamber122through inlet valve128. When the pressure of fluid in pumping chamber122is less than the pressure in inlet port124less the pressure necessary to overcome the force of the springs in inlet valve128, inlet valve128will open and fluid will flow inwardly therethrough. Fluid will not flow backward through discharge valve130. When first and second plungers132and140reach the end of the suction stroke in which they are the maximum distance away from pumping chamber122, they reverse direction and move toward pumping chamber122to form the pumping cycle. When the pressure of fluid in pumping chamber122is greater than the pressure in discharge port126plus the pressure necessary to overcome the force of the springs in discharge valve130, discharge valve130will open and fluid will flow outwardly therethrough. Fluid will not flow backward through inlet valve128. It will be seen by those skilled in the art that this operation of first and second pumping sections112and114in phase with one another will produce the maximum flow of fluid through second embodiment pumping unit100.

A zero discharge configuration of second embodiment pumping unit100is when first and second pumping sections112and114operate 180 degrees out of phase with one another. That is, in this zero pumping configuration, first and second plungers132and140always move in opposite directions with respect to pumping chamber122. During a first cycle, first plunger132moves toward pumping chamber122while second plunger140moves away from pumping chamber122. During a second pumping cycle, first plunger132moves away from pumping chamber122, and second plunger140moves toward pumping chambers122. If first crankshaft136is rotated at an angle, Ø, from bottom dead center and second crankshaft144is rotated at an angle, β, from bottom dead center, then:
Ø=β−180°

With second embodiment pumping unit100in this zero pumping configuration, substantially no fluid enters pumping chamber122through inlet valve128or is discharged therefrom through discharge valve130. It will be seen by those skilled in the art that the total volume of pumping chamber122does 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

Referring now toFIG. 4, a third embodiment of the transmissionless variable output pumping unit of the present invention is shown and generally designated by the numeral150. Third embodiment pumping unit150is similar to second embodiment pumping unit100in that the cylinders are angularly disposed from one another. The same reference numerals are used for similar components. In third embodiment pumping unit150, however, plunger132can cross over plunger140as shown. This minimizes the unswept volume in pumping chamber122.

Gear Train Detail

FIGS. 5–7show different embodiments of a gear drive train to operate pumping unit10,100or150. Referring specifically toFIG. 5, one embodiment drive train200is shown. Drive train200may be used to drive any of the pumping unit embodiments previously described herein. As illustrated, drive train200is driven by a prime mover such as a diesel engine202, although other prime movers would also be acceptable. Diesel engine202has a dual power take-off201connected thereto so that rotational power is provided to a first drive shaft204and a second drive shaft206.

A first planetary gear reducer or gear train208is connected to first drive shaft204. First planetary gear reducer208has a first outer housing210with a set of planetary gears212,214, and216disposed therein and around a first sun gear215on an end of first drive shaft204. A first planet carrier217holds planetary gears,212,214, and216in relationship to one another.

Referring now toFIG. 8, details of first planet carrier217are shown. Planetary gears212,214, and216have a planetary gear shaft240,242, and244correspondingly extending therefrom. Planetary gear shafts240,242, and244fit in openings246,248, and250, respectively, in first planet carrier217. As first drive shaft204is driven by diesel engine202, first sun gear215engages and drives planetary gears212,214, and216so that they orbit around first sun gear215. It will be seen by those skilled in the art that this causes corresponding rotation of first planet carrier217. First planet carrier217has a first output shaft252which is integral with or connected to first crankshaft36or136. A speed reducer (not shown) of a kind known in the art may be used between first output shaft252and first crankshaft36or136if desired.

Similarly, a second planetary gear reducer or gear train218is connected to second drive shaft206. Second planetary gear reducer218has a second outer housing220with a set of planetary gears222,224, and226disposed therein and around a second sun gear225on an end of second drive shaft206. A second planet carrier227holds planetary gears222,224, and226in relationship to one another.

Second planet carrier227is substantially identical to first planet carrier217previously described and shown inFIG. 8. Second planet carrier227has a second output shaft254that is integral with or connected to second crankshaft44or144. Again, a speed reducer (not shown) of a kind known in the art may be used between second output shaft254and second crankshaft44or144if desired.

First outer housing210is fixed and cannot rotate. Second outer housing220is not fixed. It may be rotated about second drive shaft206. An adjustment mechanism228is used to rotate second outer housing220by an angle corresponding to the desired phase angle relationship between first and second pumping sections12and14, such as the maximum and zero pumping configurations previously described or anything in between. In the embodiment ofFIG. 5, adjustment mechanism228is shown as a lever230. Lever230can be actuated by hand or by some other means, such as a pneumatic or hydraulic cylinder (not shown).

Referring now toFIG. 6, a different adjustment mechanism228′ is shown having a spur gear drive. In this embodiment, planetary gears222,224, and226and second planet carrier227are the same as previously described. Planetary gears222,224, and226are disposed around second sun gear225and within a second outer housing in the form of a first spur gear232. A second spur gear234is engaged with the geared surface of first spur gear232and is mounted on a gear shaft236. Gear shaft236can be driven by any means known in the art such as a rotary actuator, servo motor, etc.

Referring now toFIG. 7, an additional adjustment mechanism228″ is shown having a worm gear drive. In this embodiment, planetary gears222,224, and226and second planet carrier227are the same as previously described. Planetary gears222,224, and226are disposed around second sun gear225and within a second outer housing in the form of a first gear256. A worm gear258is engaged with the geared surface of first gear256. A worm gear shaft260extends from worm gear258. Worm gear shaft260can be driven by any means known in the art such as a rotary actuator, servo motor, etc.

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.