High pressure solar powered pump

Abstract

A solar powered pump assembly delivers high pressure liquid in relatively small volumes. The assembly includes a d.c. motor powered by the solar panel having a gearmotor output shaft driving a multilobe cam which acts against a lever which in turn acts against a follower assembly to reciprocate an input rod of a small reciprocating pump. A voltmeter or voltage measuring circuit is used to detect the voltage output of the solar panel and battery and interrupt operation of the pump assembly in the event the voltage output thereof falls below a predetermined value. A stroke adjustment mechanism may be used to limit the range of oscillating movement of the lever thereby leading to a wide range of daily volume output of the reciprocating pump.

Description

This invention relates to a solar powered pump that is capable of delivering small quantities of liquid at high pressure.

BACKGROUND OF THE INVENTION

Solar powered pumps are commonly used in the oil and gas industry to deliver small quantities of chemicals at remote locations where electrical power is unavailable. Although there are many potential applications inside and outside of the oil and gas industry for solar powered pumps, the current common uses are where surfactants are injected through a capillary string into a gas well in an attempt to discharge liquids from the well, corrosion inhibitors are injected into a well or pipeline or methanol is injected into a gas stream to prevent the formation of gas hydrates. Typically the pump delivers into an 800 psig, or less, line so the pump has to generate about 800 psig outlet pressure.

There are situations where greater outlet pressure is needed, as where the well being pumped into operates at a higher pressure, where methanol is injected upstream of a choke, or where chemicals are injected into high pressure flow lines or into high pressure gas condensate wells or the like. The industry has reacted to produce higher pressure pumps simply by making them bigger, i.e. bigger motors using more power thereby requiring larger solar panels, larger batteries and the like.

Disclosures of interest are found in U.S. Pat. Nos. 4,681,515; 4,744,334; 4,802,829; 5,244,362 and 5,293,892.

SUMMARY OF THE INVENTION

In this invention, a solar powered pump includes a solar panel, a direct current or d.c. motor having an output shaft driving a mechanism that, in turn, reciprocates a small conventional reciprocating pump. The mechanism driven by the d.c. motor includes a multilobe cam, a lever that is pivoted by the cam and, in turn, reciprocates the input rod of the pump. A spring returns the lever and retracts the pump input rod so the next movement of the cam again oscillates the lever, drives the pump and delivers a small quantity of high pressure liquid. By driving the d.c. motor intermittently, the amount of electrical power consumed can be reduced significantly. By also controlling the stroke of the pump, the amount of liquid delivered over time can be controlled very closely. The result is a pump having greater capabilities as the high pressure low volume pumps of the prior art using significantly smaller d.c. motors and significantly smaller solar modules while giving equal or better performance at lower costs.

It is an object of this invention to provide an improved solar powered pump that delivers high pressure liquid in small volumes.

Another object of this invention is to provide a solar powered pump assembly that provides a transmission or reduction unit between a d.c. motor and a reciprocating pump.

These and other objects and advantages of this invention will become more fully apparent as this description proceeds, reference being made to the accompanying drawings and appended claims.

IN THE DRAWINGS

FIG. 1 is a side view of a solar powered pump assembly of this invention;

FIG. 2 is an end view of the solar powered pump assembly of FIG. 1;

FIG. 3 is a schematic drawing of the pump assembly of FIGS. 1 and 2;

FIG. 4 is a view, with one wall removed, of the mechanism used to convert rotation of the motor into reciprocation of the pump;

FIG. 5 is an enlarged view of a rocker assembly used to connect an end of the lever to a reciprocating rod; and

FIG. 6 is an enlarged view of an assembly, analogous to FIG. 5, for connecting the end of the lever to the input of the reciprocating pump.

DETAILED DESCRIPTION

Referring to FIGS. 1-5, a pump assembly 10 of this invention comprises, as major components, a frame 12, a reservoir 14 of liquid to be pumped, a solar panel 16, a battery 18, a control module 20, a d.c. motor 22 powered by the solar panel 16, a mechanism 24 converting rotation of the motor 22 into a reciprocating motion, and a small reciprocating pump 26 having its suction 28 connected to the reservoir 14 and having an outlet or discharge 30 delivering low volumes of liquid at high pressure to a well or pipeline being served.

The frame 12 may be of any suitable type and is typically made of a noncorrodible or protected metal, such as a painted or galvanized metal, aluminum, stainless steel or the like, and is of sufficient strength and durability to support and house the various components of the pump assembly 10.

The reservoir 14 is typically a plastic container of sufficient volume to hold a substantial amount of the pumped liquid. A typical application will involve pumping perhaps five gallons of liquid per day, so a one hundred eighty tank will provide substantial operating time before refilling.

The solar panel 16 may be of any suitable size and type. One size pump assembly of this invention uses a fifty five watt solar panel and a fifty ampere battery powering a 1/20th horsepower d.c. motor and has proved suitable during endurance tests.

The control module 20 provides many conventional functions and some unconventional functions as pointed out hereinafter. Conventionally, the control module 20 delivers electricity to the d.c. motor 22 intermittently rather than continuously so the motor 22 is driven, for example, four seconds on and twenty seconds off with the on and off times being adjustable to provide a wide range of volume adjustment of the pump assembly 10 while minimizing the consumption of electricity. Unconventionally, the control module 20 includes a circuit or voltmeter 32 for measuring the voltage output of the solar panel 16 and/or battery 18 and prevents delivery of electricity to the pump 22 when the voltage falls below a preselected value. For example, in a system designed to operate at twelve volts, when the voltage measured by the circuit 32 falls below ten volts, a subcircuit 34 of the control module 20 deactivates the pump assembly 10 by opening a switch 36 until such time as solar energy falling on the panel 16 is sufficient to raise the voltage level to a preselected value, for example, twelve volts.

The d.c. motor 22 is of conventional design and preferably includes a gearmotor end 38 having an output shaft 40 extending into a sealed compartment 42 comprising part of the mechanism 24. Although the size and capacity of the motor 22 may vary significantly, depending on the designed size and capacity of the pump assembly 10, a successful design has incorporated a 1/20 horsepower d.c. motor having a five ampere rated input with a gear reducer end providing a nominal 32 rpm rotating output shaft 40 sealed by an O-ring type seal (not shown) against a wall 44 of the compartment 42.

As shown best in FIG. 4, the mechanism 24 is housed inside the compartment 42 which is filled with a suitable lubricating oil and which accordingly has a removable cover 46 closing one side of the compartment 42. The mechanism 24 comprises a multilobe cam 48 attached to the end of the shaft 40. The cam 48 preferably provides three lobes 50 that reciprocate the pump 26 three times per revolution of the shaft 40. The exact number of lobes on the cam 48 depends on the rotational speed and torque output of the gearmotor shaft 40. The cam 48 operates against a lever 52 which is pivoted to the compartment wall 44 by a pivot pin 54 and accordingly moves the lever 52 in a clockwise direction. A return spring assembly 56 operates on the lever 52 and biases the lever 52 in a counterclockwise direction when each cam lobe 50 retreats from engagement with the lever 52.

The opposite end of the lever 52 works against a follower assembly 58 to convert oscillation of the lever 52 into reciprocation of an input rod 60 of the pump 26. The follower assembly 58 includes a rod 62 connected to the input rod 60 in any suitable fashion in order to both push and pull on the rod 60. The rod 62 extends through a metal bushing 64 extending through a wall 66 of the compartment 42. The bushing 64 includes a body 68 having a threaded end and a nut 70 captivating the bushing 64 to the wall 66. A series of O-ring seals 71 seal between the rod 62 and the bushing body 68 and between the bushing body 68 and the wall 66.

The follower assembly 58 also includes a rocker assembly 72 for converting pivotal movement of the end of the lever 52 into reciprocating movement of the rod 62. To this end, the rocker assembly 72 includes a washer or backer plate 74 secured to the rod 62 by a weldment 76 and having an arcuate or partially spherical abutment 78 loosely mounted on the rod 62 and thereby captivated between the end of the lever 52 and the backer plate 74. The rocker assembly 72 also includes a similar washer or backer plate 80 pinned to the rod 62 by a cotter key 82 or other removable device. A partially spherical abutment 84 is loosely mounted on the rod 62 and is thereby captivated between the end of the lever 52 and the backer plate 80. It will accordingly be seen that oscillation of the end of the lever 52 alternately pushes and pulls on the partially spherical abutments 78, 82 and thereby alternately pushes and pulls on the rod 62 thereby reciprocating the rod 62 and reciprocating the input rod 60 of the pump 26. It will also be seen that removing the cotter key 82 allows the spherical abutment 84 to be removed and replaced. By disconnecting the rods 60, 62, the rod 62 may be shifted to allow the spherical abutment 78 to be removed and replaced.

The pump 26 is a conventional low volume reciprocating pump of the type that has been used for decades in the oil and gas industry to deliver small quantities of liquid. A typical pump is commercially available from TXAM Inc, Corpus Christi, Tex. as a Model 5010-60. The pump 26 provides a body 86 having a threaded end 88 captivated to a partition wall 90 by a nut 92. As suggested in FIG. 2, a removable cover 94 may be provided to enclose the compartment 42 and partition wall 90.

An important feature of this invention is the ability to adjust the stroke of the pump 26 in order to more closely control the volume output of the pump 26. To this end, a stroke adjuster 96 includes a hand wheel 98 having a threaded shaft 100 extending through an internally threaded bushing 102 fixed to the partition wall 90 and a locknut 104 selectively fixes the axial position of the threaded shaft 100. A threaded end of the shaft 100 extends into an externally smooth, internally threaded rod 106 which is sealed by a bushing 108 in the wall 66 of the compartment 42 and which allows axial movement of the rod 106. The end 110 of the rod 106 may be extended into the path of movement of the lever 52 and thereby limit the amount of pivotal or oscillatory movement of the lever 52 thereby limiting the range of reciprocating movement of the rod 62 and thereby limiting the range of reciprocating movement of the input rod 60 to control the volume output of the pump 26 on each stroke of the input rod 60. Retracting movement of the rod 106 is limited in any suitable manner, as by placing a shoulder 112 on the rod 106 or making the rod 106 larger adjacent the end 110. It will accordingly be seen that by adjusting the amount of rotation of the motor shaft 40 and limiting the movement of the lever 52, a wide range of adjustment of the daily volume output of the pump 26 is easily achieved.

As shown in FIG. 2, the discharge 30 of the pump 26 delivers high pressure liquid to a piping assembly 114 including a pressure gauge 116, a conduit 118 leading to the site of use of the pumped liquid and a pressure bypass conduit 120 leading to the tank 14. A pressure relief valve 122 limits the maximum pressure delivered to the output conduit 118, in a conventional manner.

Referring to FIG. 6, there is illustrated another follower assembly 124 for connecting the output end of the lever 126 to a rod 128 which pushes and pulls on the input rod 60 of the pump 26. The follower assembly 124 includes brackets or guides 130 which constrain movement of a cylindrical body 132 in an axial direction as suggested by the arrow 134. A notch 136 provided in the body 132 receives a ball or other low friction device 138 for reciprocating the body 132 and rod 128 in response to oscillating movement of the lever 126.

It will be apparent that considerable leeway exists in sizing and selecting the d.c. motor, the gear reductions provided by the gear motor end, the solar panel, the number of lobes on the cam, the size of the lever, position of its pivot pin and the like. It will accordingly be seen that the drain on the battery 18 and solar panel 16 is much reduced by this invention, meaning that smaller solar panels, smaller d.c. motors, higher pressures, larger volumes, or combinations of these advantages is allowed by this invention.

Although this invention has been disclosed and described in its preferred forms with a certain degree of particularity, it is understood that the present disclosure of the preferred forms is only by way of example and that numerous changes in the details of operation and in the combination and arrangement of parts may be resorted to without departing from the spirit and scope of the invention as hereinafter claimed.

Claims

1. A high pressure low volume pump assembly comprising

a solar panel,

a d.c. motor powered by the solar panel and having an output shaft providing at least one cam lobe,

a lever abutting the cam and pivotable about an axis,

a return mechanism biasing the lever toward the cam, and

a reciprocating pump having an input rod and a follower assembly on the input rod abutting the lever so that rotation of the cam causes reciprocation of the input rod thereby powering the reciprocating pump.

2. The high pressure low volume pump assembly of claim 1 further comprising an oil filled compartment having therein the cam, the lever, the return mechanism and the follower, the motor output shaft and pump input rod extending-through a wall of the compartment.

3. The high pressure low volume pump assembly of claim 2 wherein the follower assembly comprises an auxiliary rod coaxial with the input rod of the reciprocating pump, the auxiliary rod extending through a wall of the compartment and a rocker assembly connecting the auxiliary rod and the lever for reciprocating the auxiliary rod upon oscillation of the lever.

4. The high pressure low volume pump assembly of claim 1 wherein the cam comprises multiple lobes.

5. The high pressure low volume pump assembly of claim 1 wherein the cam comprises three lobes.

6. The high pressure low volume pump assembly of claim 1 further comprising a battery for storing electrical energy from the solar panel and a control system for the d.c. motor including a device for measuring voltage output of the battery and a system for interrupting operation of the d.c. motor when the measured voltage output falls below a predetermined value.

7. The high pressure low volume pump assembly of claim 1 wherein the follower assembly comprises an auxiliary rod coaxial with the input rod of the reciprocating pump and a rocker assembly connecting the auxiliary rod and the lever for reciprocating the auxiliary rod upon oscillation of the lever, the rocker assembly comprising a pair of arcuate abutments loosely mounted on the auxiliary rod and facing and abutting the lever and a backer plate for each arcuate abutment constraining movement of the arcuate abutments away from the lever.

8. The high pressure low volume pump assembly of claim 7 wherein the arcuate abutments are partially spherical.

9. The high pressure low volume pump assembly of claim 1 further comprising a selector for limiting pivotal movement of the lever about the axis and thereby limiting movement of the input rod of the reciprocating pump and limiting volume output of the reciprocating pump.

10. The high pressure low volume pump assembly of claim 9 wherein the selector comprises a threaded rod extending into a path of movement of the lever.

11. The high pressure low volume pump assembly of claim 1 wherein the follower assembly comprises a body mounted for axial movement and providing a notch therein, a low friction device connected to an output end of the lever and residing in the notch so that oscillation of the lever causes reciprocation of the input rod thereby powering the reciprocating pump.

12. A high pressure low volume pump assembly comprising

a solar panel in circuit with a battery for storing electrical energy produced by the solar panel;

a d.c. motor powered by the solar panel and battery and having an output shaft;

a reciprocating pump having an input rod;

a force transmitting device for converting rotation of the motor output shaft into reciprocation of the pump input rod; and

a control system for the d.c. motor including a device for measuring voltage output of the battery and a system for interrupting operation of the d.c. motor when the measured voltage output falls below a predetermined value.