CA1169333A - Oil well pump drives and servo control mechanisms therefor - Google Patents
Oil well pump drives and servo control mechanisms thereforInfo
- Publication number
- CA1169333A CA1169333A CA000384960A CA384960A CA1169333A CA 1169333 A CA1169333 A CA 1169333A CA 000384960 A CA000384960 A CA 000384960A CA 384960 A CA384960 A CA 384960A CA 1169333 A CA1169333 A CA 1169333A
- Authority
- CA
- Canada
- Prior art keywords
- sucker rod
- pump
- operatively connected
- invention according
- walking beam
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 239000003129 oil well Substances 0.000 title claims abstract description 17
- 230000007246 mechanism Effects 0.000 title claims description 12
- 230000005540 biological transmission Effects 0.000 claims abstract description 19
- 238000006073 displacement reaction Methods 0.000 claims abstract description 17
- 230000002706 hydrostatic effect Effects 0.000 claims abstract description 16
- 235000003642 hunger Nutrition 0.000 abstract description 2
- 206010041954 Starvation Diseases 0.000 abstract 1
- 230000037351 starvation Effects 0.000 abstract 1
- 239000003921 oil Substances 0.000 description 6
- 238000010586 diagram Methods 0.000 description 4
- 230000008901 benefit Effects 0.000 description 3
- 238000005086 pumping Methods 0.000 description 3
- 230000006872 improvement Effects 0.000 description 2
- 230000000712 assembly Effects 0.000 description 1
- 238000000429 assembly Methods 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 239000000295 fuel oil Substances 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 230000035939 shock Effects 0.000 description 1
- 238000004904 shortening Methods 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
- F16H61/38—Control of exclusively fluid gearing
- F16H61/40—Control of exclusively fluid gearing hydrostatic
- F16H61/42—Control of exclusively fluid gearing hydrostatic involving adjustment of a pump or motor with adjustable output or capacity
- F16H61/433—Pump capacity control by fluid pressure control means
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/12—Methods or apparatus for controlling the flow of the obtained fluid to or in wells
- E21B43/121—Lifting well fluids
- E21B43/126—Adaptations of down-hole pump systems powered by drives outside the borehole, e.g. by a rotary or oscillating drive
- E21B43/127—Adaptations of walking-beam pump systems
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B47/00—Pumps or pumping installations specially adapted for raising fluids from great depths, e.g. well pumps
- F04B47/02—Pumps or pumping installations specially adapted for raising fluids from great depths, e.g. well pumps the driving mechanisms being situated at ground level
- F04B47/022—Pumps or pumping installations specially adapted for raising fluids from great depths, e.g. well pumps the driving mechanisms being situated at ground level driving of the walking beam
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
- F16H61/38—Control of exclusively fluid gearing
- F16H61/40—Control of exclusively fluid gearing hydrostatic
- F16H61/4183—Preventing or reducing vibrations or noise, e.g. avoiding cavitations
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16H—GEARING
- F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
- F16H61/38—Control of exclusively fluid gearing
- F16H61/40—Control of exclusively fluid gearing hydrostatic
- F16H61/42—Control of exclusively fluid gearing hydrostatic involving adjustment of a pump or motor with adjustable output or capacity
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Mining & Mineral Resources (AREA)
- Mechanical Engineering (AREA)
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Environmental & Geological Engineering (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Rehabilitation Tools (AREA)
Abstract
OIL WELL PUMP DRIVES AND SERVO CONTROL MECHANISMS THEREFOR
ABSTRACT OF THE INVENTION
A hydrostatic transmission with a variable dis-placement pump and a fixed displacement axial motor is operatively connected to a walking beam type oil well pump. Included is a vibration monitor to sense the vi-brations in the sucker rod thus indicating oil starva-tion at the pump so that electric controls can operate to modify the speed of the up and down strokes of the sucker rod by means of a servo connection to the varia-ble speed pump portion of the transmission. This means that the operation of the sucker rod can be controlled so that the output of the well pump can coincide with and not exceed the inflow rate from the well to the pump.
The motor can be run in either direction with different and variable speeds for the up and down movement of the sucker rod.
ABSTRACT OF THE INVENTION
A hydrostatic transmission with a variable dis-placement pump and a fixed displacement axial motor is operatively connected to a walking beam type oil well pump. Included is a vibration monitor to sense the vi-brations in the sucker rod thus indicating oil starva-tion at the pump so that electric controls can operate to modify the speed of the up and down strokes of the sucker rod by means of a servo connection to the varia-ble speed pump portion of the transmission. This means that the operation of the sucker rod can be controlled so that the output of the well pump can coincide with and not exceed the inflow rate from the well to the pump.
The motor can be run in either direction with different and variable speeds for the up and down movement of the sucker rod.
Description
~ 1 ~9333 OIL WELL PUMP DRIVES AND SEKVO CONTROL MECHANISMS THEREFOR
BACKGROUND OF THE INVENTION
This invention relates to new and useful improve-ments in oil well pump drives of the walking beam type in-cluding a servo control mechanisms therefor.
Conventionally, said walking beam type pump drives include an eccentric which is driven by a source of power such as an electric motor or gasoline engine operatively connected to the eccentric by means of a plurality of drive belts.
: These conventional drive mechanisms require rela-tively large horsepower (amp draw of the electric motor or horsepower For a gas engine) particularly for the start-up of standard walking beam type pumps as there is a relatively ` large mass to accelerate.
Other disadvantages of conventional drive means - include the fact that conventional electric motor and V-belt drives provide a sucker rod pull at the peak force thereof, equivalent to approximately double the rated electric motor horsepower required, it being understood that the electric motor is over-sized to begin with because of the aforemen-tioned high inertia load on start-up. This means that the peak horsepower is delivered under jamming conditions and ,~,, ,~ :
1 ~ 69~3~
is generally sufficiently high to actually fracture the sucker rod. This also places strain on other components because of the maximum stress loads applied thereto, said other components including such items as gear box and other connectiny bearings between various components.
SUMMARY OF THE INVENTION
The present invention overcomes these disadvantages and permits, among other things, means whereby the mass of the walking beam assembly is accelerated at a controlled rate so that the amperage draw on start-up is of a similar value to the operating amperage.
In accordance with the invention there is provided in a drive assembly for walking beam type oil well pumps which include a walking beam, a sucker rod connected to one end thereof and being operatively connected to a deep well pump, an eccentric drive operatively connected to the other ~.
end of said walking beam and a source of power for operating ~ said eccentric and hence said walking beam, said source oP-~ power including a hydrostatic transmission assembly, said ` 20 hydrostatic transmission assembly including a variable dis-placement axial piston pump and:a fixed displacement axial piston motor operatively connected thereto; a servo control ~- mechanism including an electro servo-type valve speratively connected to:the variable displacement axial piston pump, :
;. ~, .
`: :
~ ~ &~33 electric sensor means operatively connected to said servo-valve and means to adjust said electrical sensor means whereby the speed of the upstroke of the sucker rod may be varied from 0 to maximum and further means to adjust said electric sensor means whereby the speed of the down-stroke of the sucker rod may be varied from 0 to maximum independently of the speed of the upstroke thereof.
Another aspect of the invention is to provide a dr;ve assembly for walking beam type oil well pumps com-lQ prising a walking beam mounted ~or reciprocation, a sucker rod connected to one end thereof and being operatively connected to a deep well pump, an eccentric drive opera-tively connected to the other end of the sucker rod, a source of power for said eccentric and hence said walking beam, said source of power including a hydrostatic trans-: mission assembly, said hydrostatic transmission assembly including a variable displacement axial piston pump and a fixed displacement axial piston motor operatively connected thereto, and a servo control mechanism for said transmission, said servo control mechanism includ;ng an electric servo-~- valve operatively connected to the variable dlsplacement a~ial piston pump, electric sensor means operatively con-nected to said servo-valve, and means to adjust said elec-tric sensor means whereby the speed of the upstroke o~ the r -
BACKGROUND OF THE INVENTION
This invention relates to new and useful improve-ments in oil well pump drives of the walking beam type in-cluding a servo control mechanisms therefor.
Conventionally, said walking beam type pump drives include an eccentric which is driven by a source of power such as an electric motor or gasoline engine operatively connected to the eccentric by means of a plurality of drive belts.
: These conventional drive mechanisms require rela-tively large horsepower (amp draw of the electric motor or horsepower For a gas engine) particularly for the start-up of standard walking beam type pumps as there is a relatively ` large mass to accelerate.
Other disadvantages of conventional drive means - include the fact that conventional electric motor and V-belt drives provide a sucker rod pull at the peak force thereof, equivalent to approximately double the rated electric motor horsepower required, it being understood that the electric motor is over-sized to begin with because of the aforemen-tioned high inertia load on start-up. This means that the peak horsepower is delivered under jamming conditions and ,~,, ,~ :
1 ~ 69~3~
is generally sufficiently high to actually fracture the sucker rod. This also places strain on other components because of the maximum stress loads applied thereto, said other components including such items as gear box and other connectiny bearings between various components.
SUMMARY OF THE INVENTION
The present invention overcomes these disadvantages and permits, among other things, means whereby the mass of the walking beam assembly is accelerated at a controlled rate so that the amperage draw on start-up is of a similar value to the operating amperage.
In accordance with the invention there is provided in a drive assembly for walking beam type oil well pumps which include a walking beam, a sucker rod connected to one end thereof and being operatively connected to a deep well pump, an eccentric drive operatively connected to the other ~.
end of said walking beam and a source of power for operating ~ said eccentric and hence said walking beam, said source oP-~ power including a hydrostatic transmission assembly, said ` 20 hydrostatic transmission assembly including a variable dis-placement axial piston pump and:a fixed displacement axial piston motor operatively connected thereto; a servo control ~- mechanism including an electro servo-type valve speratively connected to:the variable displacement axial piston pump, :
;. ~, .
`: :
~ ~ &~33 electric sensor means operatively connected to said servo-valve and means to adjust said electrical sensor means whereby the speed of the upstroke of the sucker rod may be varied from 0 to maximum and further means to adjust said electric sensor means whereby the speed of the down-stroke of the sucker rod may be varied from 0 to maximum independently of the speed of the upstroke thereof.
Another aspect of the invention is to provide a dr;ve assembly for walking beam type oil well pumps com-lQ prising a walking beam mounted ~or reciprocation, a sucker rod connected to one end thereof and being operatively connected to a deep well pump, an eccentric drive opera-tively connected to the other end of the sucker rod, a source of power for said eccentric and hence said walking beam, said source of power including a hydrostatic trans-: mission assembly, said hydrostatic transmission assembly including a variable displacement axial piston pump and a fixed displacement axial piston motor operatively connected thereto, and a servo control mechanism for said transmission, said servo control mechanism includ;ng an electric servo-~- valve operatively connected to the variable dlsplacement a~ial piston pump, electric sensor means operatively con-nected to said servo-valve, and means to adjust said elec-tric sensor means whereby the speed of the upstroke o~ the r -
2 ~ 3 3 3 sucker rod may be varied from O to maximum and further means to adjust said electric sensor means whereby the ; speed of the downstroke of the sucker rod may be varied from O to maximum independently of the speed of the up-stroke thereof.
Another advantage of the present device is the provision of a conventional hydrostatic power source wh;ch, in conjunction with a servo control mechanism, gives complete control of the operation of the walking beam assembly and hence the oil well pump connected there-to.
A still further advantage of the present inven-tion is to provide a dev;ce of the character herewith;n descr;bed which is well suited to the purpose for which it is designed.
With the foregoing in view, and other advantages as will become apparent to those skilled in the art to which this invention relates as this specification proceeds, the invention is herein described by reference to the ac-companying drawings forming a part~ hereof, which includes - a description of the preferred typical embodiment of the principles of the present invention, in whlch:
DESCRIPTION OF THE`DRAWINGS
:
Figure 1 is a schematic diagram o-f the servo con-.
- . ., ., :
-- ~ ' ' ~' :
trol mechanism.
Figure 2 i5 a schematic diagram of a walking beam type oil well pump assembly.
Figure 3 is a schematic diagram of a hydrostatic drive for the walking beam assembly.
Figure 4 is a schematic diagram of the stroke con-troller per se.
I~n the drawings like characters of reference indi-cate corresponding parts in the different figures.
DETAILED DESCRI PTION
Proceeding therefore to describe the ;nvention gene-rally, reference should first be made to Figures 1 and 2 in which 10 shows a central pivot support for a conventional walking beam collectively designated 11 driven by an eccentric shown schematically by reference character 12 operatively con-nected to one end 13 of the walking beam. The walking beam ~s operatively connected by the other end thereof, as by pivot bearing 14, to a sucker rod 25 extending downwardly into the well (not illustrated) and being operatively connected to an :
~ 20 oil well pump 16 shown schematically.
.
Conventionally, the eccent~ric 12 is operatively connected to a source of power such as an electric motor or gas engine (not illustrated), the drive being by a plurality of V-belts.~
Counterweights 17 are situated on the end 13 of . .
: ` :
, ~ the walking beam to counterbalance the weight of the sucker rod assembly 15 which extends to the bot$om of the well.
It will therefore be appreciated that an extremely high mass is involved which, under normal circumstances, ~.
requires a relatively large horsepower motor in order to start up the operation of the walking beam and the sucker rod assembly. It will also be appreciated that this large horsepower with a relatively large amperage draw, is not necessary to operate the assembl~y once it is up to opera-ting speed, but that such large horsepower is available in the event that Jamming occurs in the sucker rod and/or pump assembly and it is this additional horsepower that causes wear and sometimes breakage of the various compo- ~
nents~apart from the fact that power requirements are also `
heavY-Flgure 1 shows schematically the improvements con-tained within this invention.
Reference character 18 shows generally, a hydrosta-tic transmission which includes a relatively small electric motor 19 o~peratively connected ~to a va~riable displacement axial pi~ston pump collect~ively des;gnate~d 20;dri~ving a fix-ed displacement axiàl piston motor collectively designated 21, the output shaft 22 of whlch is oper~atively connected to t~he ecc;entric~12 of the wal~kin~g beam~assembly Via a gear-~ox 22A. ~Shaft 22 may be directly connected~to the gearbox as shown or may be connected~via V-belts.
:" :
:
- ~ ,, ' In detail, Figure 3 shows schematically, the con~
struction and operation o~ the hydrostatic transmission which is substantially conventional. The electric motor 19 (or gas engine) is operatively connected to the input shaft 23 of the pump 20 which is provided with a variable swash plate 24 controlled by servo pistons 25 which in turn are operated by a control valve 26 normally manually operated by means of a control lever 27.
Oil reservoir 28 is connected via line 29 to a charge pump 30 and thence to the operating pistons 31.
High pressure oil flows via conduit 32, to the axial piston motor 21, with the other conduit 33 completing the circuit to the pump 20.
The motor 21 inc1udes a fixed swash plate 34 which is operatively connected via the pistons 35, to the lines 32 and 33. The swash plate 34 drives the output shaft Z2 which is operatively connected to the eccentric 12 as hereinbefore described.
In the present invention, the control valve 2~ is : 20 replaced by an electric servo valve 36 which is of conven-~ tional construction and which is connected by cables 37 to - an electric sensor assembly collectively designated 38. This electric sensor 38 includes gauges 39 and 40 and controls 39A
and 40A ~or setting and controlling manually the ,i :
, .
~, . .. .
1 3 6~333 upstroke and downstroke of the sucker rod 15 respectively.
Alternatively, a vibration monitor 41 is shown schematically in Figure l~ operatively connected to a trans-ducer 42 which in turn provides input to the electr;c sensor means 38.
It is a well known fact that if the upstroke of the sucker rod 15 is too fast, thereby starving the pump 15 of oil, vibration is i~nduced within the sucher rod 15.
The vlbration monitor operatively connected to the sensor means 38 permits automatic adjustment of the up-stroke speed thus enabling the output of the pump to coincide with or not exceed the inflow rate of the oil from the well to the pump inlet.
Such walking beam pumps are often used for rela-tively heavy oil so that the downstroke of the sucker rod is often desirably slower than the upstroke as the piston assem-bly on the lower end of the sucker rod has to pass through the oil collected in the pump.
~ The controls in the electric sensor enables the `;~ 20 speeds of the upstroke and downstroke of the sucker rod~to be adjusted independently of one another to provide optimum pumping conditlons. ~ ~
The design of variable displacement axia1 piston pumps are such that when the~ swash plate 24 is neutral, there is no output from the pump. As the swash plate is :
: :
::
: . . ~ . ~ . :
:
.
:: ` :` ~ `: : :
1 1 ~9333 inclined in one direction or the other, minimum output is provided to the motor 21 so that by starting at 0 and in-creasing the pum~ output to the desired rotational speed, the relatively large horsepower requirements of convention-al motors~ are eliminated. The present drive accelerates the mass at a slow controlled rate so that the amperage draw on the startup is of similar value to the full opera-ting amperage.
Secondly, the drive is infinitely variable from 0 to maximum in either direction. Maximum is that speed attainable by the maximum volume of the pump 20 and the volume of the fluid used in the hydraulic motor 21 known as the volumetric displacement of the motor. This allows full control of the upstroke and downstroke speeds of the sucker rod independently of each other and provides the opportunity to "fine tune" the pumping rate to coincide with the inflow rate of oil in the well therefore provid-ing maximum pumping efficiency which is an extremely im-portant consideration for walking beam type oil well pumps.
Thirdly, t~he drive control controls the stress on all rotating and reciprocating components, bu~t more impor-tantly, controls the stress on the sucker rod. As men-tioned previously, the conventional electric motor and V-belt drive will provide a rod pull at a peak force equiva-.. .. .:, ~
.
. . , .
1 ~ 69333 lent to approximately double the rated electric motor horse-power required to operate the pump once speed is obtained.
The electric motor has to be over-sized because of the high ; inertia load on start-up so that the peak horsepower deli-vered under a jamming condition is generally suf~iciently high to actually fracture the sucker rod. The hydraulic pump 20 oF the present invention is provided with a pump . pressure over-ride control~ e;ther hydraulic or electric (not illustrated) that will~ control th~e maximum pressure : 10 and hence the output torque 24 which l~n turn of course controls the force operating on the su~cker rod (in order to prevent large ~shock loads from occurring and thereby decreasing sucker rod damage).
The use of the hydrostatic transmission enables the operator to infinitely vary the speed of the upstroke of the sucker rod from 0 to maximum and also to infinitely ;~ ~ vary the speed of the downstroke of the sucker rod from 0 to maximum independently of the upstroke speed.
~: It enables the control;to be obtained as to the maximum s~tress applied to the~sucker rod~by controlling the maximum output~pressure of the hydrauli:c pump 20.
It controls~the stress on~ the rotating parts in-~cluding the:el:ectric~motor~by startlng the entlre mass from a 0 speed and accelerating very slowly thereby eli-~ ? : : : : `
::
' , :
1 1 693~3 minating power surges in the electric motor.
It controls the outflow rate of the individual well to coincide with the inflow rate underground. This may be accomplished either manually or automatically by picking up sucker rod vibrations and converting them to a signal that would automatically change the pump time cycle to coincide with the required flow rate.
It will also control the rotation of the eccen-tric to enable rotation in either direction to be obtain-ed without reversing the rotation of the electric motor.
Apart from the foregoing, it will be obvious to those skilled in the art that the velocity profile of the upstroke and downstroke may readily be completely control-led in order to provide a constant lineal speed by short-ening the accelerating and decelerating time span of the rotary motion eccentric.
Finally, complete remote control of all the con-trol aspects mentioned previously, may readily be obtained by conventional equipment.
Since var~lous modifications can be made in my in-vention as hereinabove described, and many apparently wide-ly different embodlments of same made within the spirit and scope of the claims without departing ~rom such spirit and ~ scope, it is intended that all matter contained in the ac-..
. . . ~:
1 ~ 6a333 companying specification shall be interpreted as illustra-tive only and not in a limiting sense.
, :
. :
:
:
: ,, - : ~ . , . .
Another advantage of the present device is the provision of a conventional hydrostatic power source wh;ch, in conjunction with a servo control mechanism, gives complete control of the operation of the walking beam assembly and hence the oil well pump connected there-to.
A still further advantage of the present inven-tion is to provide a dev;ce of the character herewith;n descr;bed which is well suited to the purpose for which it is designed.
With the foregoing in view, and other advantages as will become apparent to those skilled in the art to which this invention relates as this specification proceeds, the invention is herein described by reference to the ac-companying drawings forming a part~ hereof, which includes - a description of the preferred typical embodiment of the principles of the present invention, in whlch:
DESCRIPTION OF THE`DRAWINGS
:
Figure 1 is a schematic diagram o-f the servo con-.
- . ., ., :
-- ~ ' ' ~' :
trol mechanism.
Figure 2 i5 a schematic diagram of a walking beam type oil well pump assembly.
Figure 3 is a schematic diagram of a hydrostatic drive for the walking beam assembly.
Figure 4 is a schematic diagram of the stroke con-troller per se.
I~n the drawings like characters of reference indi-cate corresponding parts in the different figures.
DETAILED DESCRI PTION
Proceeding therefore to describe the ;nvention gene-rally, reference should first be made to Figures 1 and 2 in which 10 shows a central pivot support for a conventional walking beam collectively designated 11 driven by an eccentric shown schematically by reference character 12 operatively con-nected to one end 13 of the walking beam. The walking beam ~s operatively connected by the other end thereof, as by pivot bearing 14, to a sucker rod 25 extending downwardly into the well (not illustrated) and being operatively connected to an :
~ 20 oil well pump 16 shown schematically.
.
Conventionally, the eccent~ric 12 is operatively connected to a source of power such as an electric motor or gas engine (not illustrated), the drive being by a plurality of V-belts.~
Counterweights 17 are situated on the end 13 of . .
: ` :
, ~ the walking beam to counterbalance the weight of the sucker rod assembly 15 which extends to the bot$om of the well.
It will therefore be appreciated that an extremely high mass is involved which, under normal circumstances, ~.
requires a relatively large horsepower motor in order to start up the operation of the walking beam and the sucker rod assembly. It will also be appreciated that this large horsepower with a relatively large amperage draw, is not necessary to operate the assembl~y once it is up to opera-ting speed, but that such large horsepower is available in the event that Jamming occurs in the sucker rod and/or pump assembly and it is this additional horsepower that causes wear and sometimes breakage of the various compo- ~
nents~apart from the fact that power requirements are also `
heavY-Flgure 1 shows schematically the improvements con-tained within this invention.
Reference character 18 shows generally, a hydrosta-tic transmission which includes a relatively small electric motor 19 o~peratively connected ~to a va~riable displacement axial pi~ston pump collect~ively des;gnate~d 20;dri~ving a fix-ed displacement axiàl piston motor collectively designated 21, the output shaft 22 of whlch is oper~atively connected to t~he ecc;entric~12 of the wal~kin~g beam~assembly Via a gear-~ox 22A. ~Shaft 22 may be directly connected~to the gearbox as shown or may be connected~via V-belts.
:" :
:
- ~ ,, ' In detail, Figure 3 shows schematically, the con~
struction and operation o~ the hydrostatic transmission which is substantially conventional. The electric motor 19 (or gas engine) is operatively connected to the input shaft 23 of the pump 20 which is provided with a variable swash plate 24 controlled by servo pistons 25 which in turn are operated by a control valve 26 normally manually operated by means of a control lever 27.
Oil reservoir 28 is connected via line 29 to a charge pump 30 and thence to the operating pistons 31.
High pressure oil flows via conduit 32, to the axial piston motor 21, with the other conduit 33 completing the circuit to the pump 20.
The motor 21 inc1udes a fixed swash plate 34 which is operatively connected via the pistons 35, to the lines 32 and 33. The swash plate 34 drives the output shaft Z2 which is operatively connected to the eccentric 12 as hereinbefore described.
In the present invention, the control valve 2~ is : 20 replaced by an electric servo valve 36 which is of conven-~ tional construction and which is connected by cables 37 to - an electric sensor assembly collectively designated 38. This electric sensor 38 includes gauges 39 and 40 and controls 39A
and 40A ~or setting and controlling manually the ,i :
, .
~, . .. .
1 3 6~333 upstroke and downstroke of the sucker rod 15 respectively.
Alternatively, a vibration monitor 41 is shown schematically in Figure l~ operatively connected to a trans-ducer 42 which in turn provides input to the electr;c sensor means 38.
It is a well known fact that if the upstroke of the sucker rod 15 is too fast, thereby starving the pump 15 of oil, vibration is i~nduced within the sucher rod 15.
The vlbration monitor operatively connected to the sensor means 38 permits automatic adjustment of the up-stroke speed thus enabling the output of the pump to coincide with or not exceed the inflow rate of the oil from the well to the pump inlet.
Such walking beam pumps are often used for rela-tively heavy oil so that the downstroke of the sucker rod is often desirably slower than the upstroke as the piston assem-bly on the lower end of the sucker rod has to pass through the oil collected in the pump.
~ The controls in the electric sensor enables the `;~ 20 speeds of the upstroke and downstroke of the sucker rod~to be adjusted independently of one another to provide optimum pumping conditlons. ~ ~
The design of variable displacement axia1 piston pumps are such that when the~ swash plate 24 is neutral, there is no output from the pump. As the swash plate is :
: :
::
: . . ~ . ~ . :
:
.
:: ` :` ~ `: : :
1 1 ~9333 inclined in one direction or the other, minimum output is provided to the motor 21 so that by starting at 0 and in-creasing the pum~ output to the desired rotational speed, the relatively large horsepower requirements of convention-al motors~ are eliminated. The present drive accelerates the mass at a slow controlled rate so that the amperage draw on the startup is of similar value to the full opera-ting amperage.
Secondly, the drive is infinitely variable from 0 to maximum in either direction. Maximum is that speed attainable by the maximum volume of the pump 20 and the volume of the fluid used in the hydraulic motor 21 known as the volumetric displacement of the motor. This allows full control of the upstroke and downstroke speeds of the sucker rod independently of each other and provides the opportunity to "fine tune" the pumping rate to coincide with the inflow rate of oil in the well therefore provid-ing maximum pumping efficiency which is an extremely im-portant consideration for walking beam type oil well pumps.
Thirdly, t~he drive control controls the stress on all rotating and reciprocating components, bu~t more impor-tantly, controls the stress on the sucker rod. As men-tioned previously, the conventional electric motor and V-belt drive will provide a rod pull at a peak force equiva-.. .. .:, ~
.
. . , .
1 ~ 69333 lent to approximately double the rated electric motor horse-power required to operate the pump once speed is obtained.
The electric motor has to be over-sized because of the high ; inertia load on start-up so that the peak horsepower deli-vered under a jamming condition is generally suf~iciently high to actually fracture the sucker rod. The hydraulic pump 20 oF the present invention is provided with a pump . pressure over-ride control~ e;ther hydraulic or electric (not illustrated) that will~ control th~e maximum pressure : 10 and hence the output torque 24 which l~n turn of course controls the force operating on the su~cker rod (in order to prevent large ~shock loads from occurring and thereby decreasing sucker rod damage).
The use of the hydrostatic transmission enables the operator to infinitely vary the speed of the upstroke of the sucker rod from 0 to maximum and also to infinitely ;~ ~ vary the speed of the downstroke of the sucker rod from 0 to maximum independently of the upstroke speed.
~: It enables the control;to be obtained as to the maximum s~tress applied to the~sucker rod~by controlling the maximum output~pressure of the hydrauli:c pump 20.
It controls~the stress on~ the rotating parts in-~cluding the:el:ectric~motor~by startlng the entlre mass from a 0 speed and accelerating very slowly thereby eli-~ ? : : : : `
::
' , :
1 1 693~3 minating power surges in the electric motor.
It controls the outflow rate of the individual well to coincide with the inflow rate underground. This may be accomplished either manually or automatically by picking up sucker rod vibrations and converting them to a signal that would automatically change the pump time cycle to coincide with the required flow rate.
It will also control the rotation of the eccen-tric to enable rotation in either direction to be obtain-ed without reversing the rotation of the electric motor.
Apart from the foregoing, it will be obvious to those skilled in the art that the velocity profile of the upstroke and downstroke may readily be completely control-led in order to provide a constant lineal speed by short-ening the accelerating and decelerating time span of the rotary motion eccentric.
Finally, complete remote control of all the con-trol aspects mentioned previously, may readily be obtained by conventional equipment.
Since var~lous modifications can be made in my in-vention as hereinabove described, and many apparently wide-ly different embodlments of same made within the spirit and scope of the claims without departing ~rom such spirit and ~ scope, it is intended that all matter contained in the ac-..
. . . ~:
1 ~ 6a333 companying specification shall be interpreted as illustra-tive only and not in a limiting sense.
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. :
:
:
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Claims
WHAT I CLAIM AS MY INVENTION IS:
(1) In a drive assembly for walking beam type oil well pumps which include a walking beam, a sucker rod connected to one end thereof and being operatively connec-ted to a deep well pump, an eccentric drive operatively connected to the other end of said walking beam and a source of power for operating said eccentric drive and hence said walking beam, said source of power including a hydrostatic transmission assembly, said hydrostatic trans-mission assembly including a variable displacement axial piston pump and a fixed displacement axial piston motor operatively connected thereto; a servo control mechanism for said transmission, said servo control mechanism in-cluding an electro servo-type valve operatively connected to the variable displacement axial piston pump, and an electric sensor operatively connected to said servo-valve, said electrical sensor being adjustable and controllable whereby the speed of the upstroke and the downstroke of the sucker rod may be varied from O to maximum independently of one another.
(2) The invention according to Claim 1 which includes a sucker rod vibration monitor operatively connec-ted to said sucker rod and to said electric sensor means, to adjust and control the outflow rate of the oil well to coincide with and not exceed the inflow rate to the oil well pump.
(3) The invention according to Claim 1 in which said electric sensor means includes means to sense the up-per and lower positions of the stroke of said sucker rod.
(4) The invention according to Claim 2 in which said electric sensor means includes means to sense the up-per and lower positions of the stroke of said sucker rod.
(5) A drive assembly for walking beam type oil well pumps comprising a walking beam mounted for recipro-cation, a sucker rod connected to one end thereof and be-ing operatively connected to a deep well pump, an eccen-tric drive operatively connected to the other end of the sucker rod, a source of power for said eccentric drive and hence said walking beam, said source of power including a hydrostatic transmission assembly, said hydrostatic trans-mission assembly including a variable displacement axial piston pump and a fixed displacement axial piston motor operatively connected thereto, and a servo control mecha-nism for said transmission, said servo control mechanism including an electric servo-valve operatively connected to the variable displacement axial piston pump, an elec-tric sensor operatively connected to said servo-valve, said electric sensor being adjustable and controllable whereby the speed of the upstroke and downstroke of the sucker rod may be varied from O to maximum independently of one another.
(6) The invention according to Claim 5 which includes a sucker rod vibration monitor operatively connec-ted to said sucker rod and to said electric sensor, to con-trol the outflow rate of the oil well pump to coincide with and not exceed the inflow rate to the oil well pump.
(7) The invention according to Claim 5 in which said electric sensor means includes means to sense the up-per and lower positions of the stroke of said sucker rod.
(8) The invention according to Claim 6 in which said electric sensor means includes means to sense the up-per and lower positions of the stroke of said sucker rod.
(9) The invention according to Claim 5 which includes means to control the maximum pressure of the hydrostatic transmission thereby controlling the maximum stress on the sucker rod.
(10) The invention according to Claim 6 which in-cludes means to control the maximum pressure of the hydro-static transmission thereby controlling the maximum stress on the sucker rod.
(11) The invention according to Claim 7 which includes means to control the maximum pressure of the hy-drostatic transmission thereby controlling the maximum stress on the sucker rod.
(12) The invention according to Claim 8 which includes means to control the maximum pressure of the hy-drostatic transmission thereby controlling the maximum stress on the sucker rod.
(1) In a drive assembly for walking beam type oil well pumps which include a walking beam, a sucker rod connected to one end thereof and being operatively connec-ted to a deep well pump, an eccentric drive operatively connected to the other end of said walking beam and a source of power for operating said eccentric drive and hence said walking beam, said source of power including a hydrostatic transmission assembly, said hydrostatic trans-mission assembly including a variable displacement axial piston pump and a fixed displacement axial piston motor operatively connected thereto; a servo control mechanism for said transmission, said servo control mechanism in-cluding an electro servo-type valve operatively connected to the variable displacement axial piston pump, and an electric sensor operatively connected to said servo-valve, said electrical sensor being adjustable and controllable whereby the speed of the upstroke and the downstroke of the sucker rod may be varied from O to maximum independently of one another.
(2) The invention according to Claim 1 which includes a sucker rod vibration monitor operatively connec-ted to said sucker rod and to said electric sensor means, to adjust and control the outflow rate of the oil well to coincide with and not exceed the inflow rate to the oil well pump.
(3) The invention according to Claim 1 in which said electric sensor means includes means to sense the up-per and lower positions of the stroke of said sucker rod.
(4) The invention according to Claim 2 in which said electric sensor means includes means to sense the up-per and lower positions of the stroke of said sucker rod.
(5) A drive assembly for walking beam type oil well pumps comprising a walking beam mounted for recipro-cation, a sucker rod connected to one end thereof and be-ing operatively connected to a deep well pump, an eccen-tric drive operatively connected to the other end of the sucker rod, a source of power for said eccentric drive and hence said walking beam, said source of power including a hydrostatic transmission assembly, said hydrostatic trans-mission assembly including a variable displacement axial piston pump and a fixed displacement axial piston motor operatively connected thereto, and a servo control mecha-nism for said transmission, said servo control mechanism including an electric servo-valve operatively connected to the variable displacement axial piston pump, an elec-tric sensor operatively connected to said servo-valve, said electric sensor being adjustable and controllable whereby the speed of the upstroke and downstroke of the sucker rod may be varied from O to maximum independently of one another.
(6) The invention according to Claim 5 which includes a sucker rod vibration monitor operatively connec-ted to said sucker rod and to said electric sensor, to con-trol the outflow rate of the oil well pump to coincide with and not exceed the inflow rate to the oil well pump.
(7) The invention according to Claim 5 in which said electric sensor means includes means to sense the up-per and lower positions of the stroke of said sucker rod.
(8) The invention according to Claim 6 in which said electric sensor means includes means to sense the up-per and lower positions of the stroke of said sucker rod.
(9) The invention according to Claim 5 which includes means to control the maximum pressure of the hydrostatic transmission thereby controlling the maximum stress on the sucker rod.
(10) The invention according to Claim 6 which in-cludes means to control the maximum pressure of the hydro-static transmission thereby controlling the maximum stress on the sucker rod.
(11) The invention according to Claim 7 which includes means to control the maximum pressure of the hy-drostatic transmission thereby controlling the maximum stress on the sucker rod.
(12) The invention according to Claim 8 which includes means to control the maximum pressure of the hy-drostatic transmission thereby controlling the maximum stress on the sucker rod.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000384960A CA1169333A (en) | 1981-09-01 | 1981-09-01 | Oil well pump drives and servo control mechanisms therefor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000384960A CA1169333A (en) | 1981-09-01 | 1981-09-01 | Oil well pump drives and servo control mechanisms therefor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1169333A true CA1169333A (en) | 1984-06-19 |
Family
ID=4120848
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000384960A Expired CA1169333A (en) | 1981-09-01 | 1981-09-01 | Oil well pump drives and servo control mechanisms therefor |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1169333A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0474338A1 (en) * | 1990-07-02 | 1992-03-11 | Honda Giken Kogyo Kabushiki Kaisha | Hydraulic transmission system |
| US5259193A (en) * | 1989-07-28 | 1993-11-09 | Honda Giken Kogyo Kabushiki Kaisha | Hydraulic transmission system |
-
1981
- 1981-09-01 CA CA000384960A patent/CA1169333A/en not_active Expired
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5259193A (en) * | 1989-07-28 | 1993-11-09 | Honda Giken Kogyo Kabushiki Kaisha | Hydraulic transmission system |
| EP0474338A1 (en) * | 1990-07-02 | 1992-03-11 | Honda Giken Kogyo Kabushiki Kaisha | Hydraulic transmission system |
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| MKEX | Expiry |