CA1196547A - Hydraulic oil pump - Google Patents
Hydraulic oil pumpInfo
- Publication number
- CA1196547A CA1196547A CA000405100A CA405100A CA1196547A CA 1196547 A CA1196547 A CA 1196547A CA 000405100 A CA000405100 A CA 000405100A CA 405100 A CA405100 A CA 405100A CA 1196547 A CA1196547 A CA 1196547A
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- CA
- Canada
- Prior art keywords
- pump
- reservoir
- motor
- hydraulic
- stroke
- 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
Classifications
-
- 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
- F04B47/04—Pumps or pumping installations specially adapted for raising fluids from great depths, e.g. well pumps the driving mechanisms being situated at ground level the driving means incorporating fluid means
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Fluid-Pressure Circuits (AREA)
Abstract
Abstract:
A jack pump of the type used to pump crude oil from oil wells. The jack pump comprises a reciprocating hydraulic motor fox operating sucker rods extending down the well to a down hole pump. The motor has a power stroke for lifting the sucker rods and a dissipating stroke allowing the sucker rods to fall again. The jack pump includes a variable displacement hydraulic pump, a gas-charged accumulator, a reservoir for hydraulic fluid and a hydraulic flow control circuit connecting the motor, pump, accumulator and reservoir. The flow control circuit allows the jack pump to operate as follows. During the power stroke of the hydraulic motor, pressurized fluid flows from the accumulator to the motor to operate the latter. During the dissipating stroke of the motor, fluid flows from the motor to the reservoir. During both the power stroke and the dissipating stroke, the pump operates continuously and under balanced load to charge hydraulic fluid from the reservoir to the accumulator.
A jack pump of the type used to pump crude oil from oil wells. The jack pump comprises a reciprocating hydraulic motor fox operating sucker rods extending down the well to a down hole pump. The motor has a power stroke for lifting the sucker rods and a dissipating stroke allowing the sucker rods to fall again. The jack pump includes a variable displacement hydraulic pump, a gas-charged accumulator, a reservoir for hydraulic fluid and a hydraulic flow control circuit connecting the motor, pump, accumulator and reservoir. The flow control circuit allows the jack pump to operate as follows. During the power stroke of the hydraulic motor, pressurized fluid flows from the accumulator to the motor to operate the latter. During the dissipating stroke of the motor, fluid flows from the motor to the reservoir. During both the power stroke and the dissipating stroke, the pump operates continuously and under balanced load to charge hydraulic fluid from the reservoir to the accumulator.
Description
~ydraulic oil pump Background of the invention I. Field of the Invention This invention relates to jack pumps of the type used to pump crude oil from oil wells.
II. Description of the Prior Art When an oil well has insufficient pressure to force the oil to the surface, pumping equipment is used to raise the oil. The conventional method of lifting oil from the bottom of an oil well employs a reciprocating rod connected to a device at the surface which causes the rod to move up and down. At its lower end, the reciprocating rod is connected to a displacement pump positioned below the fluid level within the oil well.
The most common type of surface device for reciprocating the rod takes the form of a walking beam supported on a vertical post. The beam is attached to the supporting vertical post by means of an interposed oscillating journal assembly connected to the centre of the beam in the conventional rockinghorse style configuration, ..~,, ..~.~
. .
.
or at one end of the beam in the unitorque and the air balance style of units. A rotating eccentric connected to one end of the rocking beam, or connected to a mid position of the end supported beams, causes the free end of the beam to move up and down. This end,being connected to the oilwell rods,causes the reciprocating pumping action.
This form of device has many well known advantages and disadvantages.
A second form of surface device consists of a verti-cally mounted hydraulic ram connected at its lower end to the reciprocating rod extending Erom the surface of the yroundO Examples of this type of surEace device are disclosed in Canadian patent 1l032,064 issued on May 30, 1978 to Canadian Foremost Ltd. ; Canadian patent 1,076,926 issued on May 6, 1980 to Canadian Foremost Ltc~. ; U.S.
patent 3~491,538 issued on January 27, 1970 to Driltrol;
and U.S. patent 4,249,376 issued on February 10, 19~1 to Weckerly.
There are numerous forms of hydraulically activated oilwell pumping units that make use of hydraulic energy to lift the sucker rods. In most instances devices and arrangments are not incorporated whereby the energy created by the downward action of the sucker rods is accumulated for reuse in support of the upward stroke action. The patents mentioned above attempt to accumulate a portion of the energy that is expended by the downward action of the sucker rods. This mav take the form of a pressurized reservoir which will contain the fluid expelled from the cylinder of the hydraulic ram or motor together with a pressuri~ed gas. On the downstroke of the piston in the cylinder the weight of the reciprocating rods is used to drlve hydraulic fluid from the cylinder into the accumulator that contains a head of pressurized qas, urther compressing the gas within ~he accumula-tor. The hwdraulic pump used to operate the hydraulicram is efEectively idling during this phase of the jl~'J
cycle. In the case of the closed loop hydraulic system the pressurized hydraulic fluid from the cylinder is directed into the suction port oE the hydraulic pump which controls the movement of the fluid during the downstroke.
During the upstroke the fluid from the accumulator is fed to the hydraulic pump where the pressure is boosted and then supplied to the hydraulic cylinder. In another form of device the gas being compressed is contained in a dry accumulator (does not contain oil). The action of the falling rods causes a piston in the gas cyclinder to compress the gasO ~he oil from the hydraulic oil cylinder is directed to the suction port of the pump and is directed to atmospheric vented storage. The pump controls the downward movement of the piston. The pump does little or no work on the downstroke. The pressurized gas exerting upward pressure within the independent cylinder forces an independent piston, that is connected by the device to the hydraulic piston, upwardly and in this way augments the lifting force of the hydraulic motor system.
Accordingly the accumulator acts to counterbalance the weight of the reciprocating ~ods so that less work has to be carried out by the hydraulic pump during the upstroke action. Because the hydraulic pump operates at no load or partial load during the downstroke of the jack pump, only half or a reduced portion of the power available to the unit during the cycle of operation is made use of. As most power supply is charged for on a maximum-use basis this results in excess ca~ital costs and o~erating cllarges .
In the patents mentioned above the speed of the piston motor action is controlled directly by the capacity of the hydraulic pump~
Summary of the Invention It is an object of the present invention to make full .
use oE the hydraulic pump and power source equipment (energizing motor) throughout the complete cycle of operation of the hydraulic jack pumpO
It is a further object of the invention, at least in preferred forms, to incorporate an adjustable facility that allows for the accumulation of a portion of the energy by the pump assembly during the downs~roke of the pumping cycleO
According to one aspect of the invention there is provided a jack pump comprising: a reciprocating hydraulic motor having a power stroke and a dissipating stroke; a hydraulic pump having an inlet and an outlet for hydraulic fluid; at least one pressurized accumulator;
a reservoir for hydraulic fluid; and a hydraulic flow con-trol circuit interconnecting said motor, pump, accumulator and reservoir, said flow control circuit comprising: first pipe means interconnecting said reservoir and the inlet of said pump for enabling the pump to draw hydraulic fluid from said reservoir second pipe means directly connecting the outlet of said pump to said at least one pressurized accumulator so that hydraulic fluid may be pumped on a continuous basis to said at least one accumulator; third pipe means connecting said at least one accumulator to said hydraulic motor to enable pressurized hydraulic fluid to pass from said accumulator to said motor to cause said power stroke; fourth pipe means connecting said hydraulic motor to said reservoir to enable hydraulic fluid from said motor to pass directly to said reservoir during said dissipating stroke; sensor means to d~termine when said motor has terminated its power stroke and its dissipating stroke respectively; and valve means controlled by said sensor means and acting on sa.id third and fourth pipe means to permit pressurized fluid to pass through said third pipe means ~or said Power stroke and through said fourth pipe means during said dissinating stroke without restrictiny the flow of fluid through said ~irst and -4a-second pipe means caused by continuous operation of said pump.
According to another aspect of the invention there is provided a method of operating a jack pump including a reciprocating hydraulic motor having a power stroke and a dis.sipating stroke, at least one pressurized accumulator, a hydraulic pump, a reservoir for hydraulic fluid and a hydraulic flow circuit interconnecting said motor, pump, accumulator and reservoir; said me~hod comprising: operat-ing said pump ,continuously throughout each cycle comprising a power stroke and a dissipating stroke of said motor to continuously charge said pressurizedaccumulator with hydraulic fluid from said reservoir; directing fluid from said accumulator to said motor during said power stroke in order to actuate said motor; and directing fluid from said motor directly to said reservoir during said dissipating stroke.
In a preferred form of the invention, the reservoir is maintained under a superatmospheric pressure.
An advantage of the invention, at least in its preferred forms, is that it can utilize a minimum power source at a level rate of usage throughout the full cycle period and that it can conserve a reasonably large portion of the energy that is expended by the downward action of the sucker rods; this conserved or accumulated energy to be used in support of the hydraulic pump, reducing the power required to charge the power accumulators inter-posed between the hydraulic pump and the hydraulic motor. The invention can also provide a means of raising the sucker rods at a rate of speed greater than that which would be possible if the pump acted directly to supply the oil volume required to move the piston upwardly in ~he mo-tor, and ~rovldes a means of allowing the sucker rods to return to their lower position unimpeded by mechanical constraints inherent within the jack pump.
It is a further advantage of the present invention, at least in preferred forms, that it can divide the upstroke action and the downstroke action of the hydraulic jack pump in order to control and maximize independently the functions of lift (upstroke) and the function of freefall (downstroke)~
The described invention, at least in the pre-ferred forms, maximizes the speed of rise of the sucker rods consistent with the capacity of the oil-well e~uipment, and maximizes the rate of fall by a self-regulating system of the sucker rods consistent with the oilwell production characteristics, and conserves the maximum amount of expended energy during the downward movement of the sucker rods, the maximum being determined by the production characteristics of the oilwell; and further utilizes the power available on a 60 second per minute basis.
This invention is designed in particular to deal with and satisfy the very difficult production problems of heavy viscous oil production.
Heavy viscous oil is produced by different methods ranging from what is termed as primary production which, in so far as jack pumps are concerned, is the pumping of the oil by a conventional downhole pump without the assistance of pressurization of the formation or heating 3~ of the oil to cause it to be less viscous; to tertiary production systems which may involve pressurizing the formation reservoir and heating the oil in ~ . In order to maximize production it is necessary to raise the pump plunger as rapidly as possible consistent with downhole considerations and eqoipment constraints and then to allow , ,~
i i the sucker rods together with the pump plunger to return to the bottom position as rapidly as possibleO During a ter~iary pxoduction cycle that employs a method of heating the oil bear-ing formation, the oil originally produced is warm and flows reasonably freely. As the cycle proqresses to its final phase, the oil becomes cooler and more viscousO As the oil becomes more viscous the oil in the production tubing tends to restrict the action of the sucker rods when falling to their bottom posit:ion. This change in rate of speed is gradual and progresC;ive. In order to allow the pump to function to permit the return of the sucker rods to the lower position as rapidly as possible throughout the changing cycle, ;t is necessary to permit a maximum degree of freefall action. In one form of the invention later described this is accomplished by accumulating a maximum amount of the energy expended by the sucker rods returniny to the lower position consistent with allowing sufficient downward force due to gravity in order to cause the rods to fall at their maximum rate of fall. This form of the invention further allows the maximization of the above action by virtue of having the energy accumulation system pursuant to the upward thrust of the piston incorporated with;n the system in such a manner as to not restrict the freefall action of the rods in any way; and by virtue of having the downthrust energy accumulation system operate entirely independent of the upward thrust system which allows for independent regulation of the downward thrust energy accumulation~ makin~ it possible to use any portion of the rod fall energy to force the downward movement of the sucker rods within the shortest possible time. The time period will adjust automatically in accordance with the change in viscosity of the crude oil within the production column.
During the period of the downward movement of the sucker rods, the hydraulic pump forces oil into the 6~
:
accumulator positioned downstream from the hydraulic pump, recharging the oil volume that was allowed to move into the cylinder during the upstroke of the 3ack pump. During the upstroke period the hydraulic pump continues to charge the accumulator. This allows full cycle utilization of pump capacity and power provided.
The upstroke action is governed by the capacity of the accumulators positioned between the hydraulic pump and the cylinder to deliver pressurized fluid to the cylinder.
10 This is regulated independently from the pump's volume capacity. This technique maximizes the speed of the upstroke~ However, the volume of fluid supplied by the pump over a full cycle is equal to that required by the cylinder during the upstroke.
The system allows:
1. the maximum upward speed of the sucker rods that their design and other production considerations will permit;
II. Description of the Prior Art When an oil well has insufficient pressure to force the oil to the surface, pumping equipment is used to raise the oil. The conventional method of lifting oil from the bottom of an oil well employs a reciprocating rod connected to a device at the surface which causes the rod to move up and down. At its lower end, the reciprocating rod is connected to a displacement pump positioned below the fluid level within the oil well.
The most common type of surface device for reciprocating the rod takes the form of a walking beam supported on a vertical post. The beam is attached to the supporting vertical post by means of an interposed oscillating journal assembly connected to the centre of the beam in the conventional rockinghorse style configuration, ..~,, ..~.~
. .
.
or at one end of the beam in the unitorque and the air balance style of units. A rotating eccentric connected to one end of the rocking beam, or connected to a mid position of the end supported beams, causes the free end of the beam to move up and down. This end,being connected to the oilwell rods,causes the reciprocating pumping action.
This form of device has many well known advantages and disadvantages.
A second form of surface device consists of a verti-cally mounted hydraulic ram connected at its lower end to the reciprocating rod extending Erom the surface of the yroundO Examples of this type of surEace device are disclosed in Canadian patent 1l032,064 issued on May 30, 1978 to Canadian Foremost Ltd. ; Canadian patent 1,076,926 issued on May 6, 1980 to Canadian Foremost Ltc~. ; U.S.
patent 3~491,538 issued on January 27, 1970 to Driltrol;
and U.S. patent 4,249,376 issued on February 10, 19~1 to Weckerly.
There are numerous forms of hydraulically activated oilwell pumping units that make use of hydraulic energy to lift the sucker rods. In most instances devices and arrangments are not incorporated whereby the energy created by the downward action of the sucker rods is accumulated for reuse in support of the upward stroke action. The patents mentioned above attempt to accumulate a portion of the energy that is expended by the downward action of the sucker rods. This mav take the form of a pressurized reservoir which will contain the fluid expelled from the cylinder of the hydraulic ram or motor together with a pressuri~ed gas. On the downstroke of the piston in the cylinder the weight of the reciprocating rods is used to drlve hydraulic fluid from the cylinder into the accumulator that contains a head of pressurized qas, urther compressing the gas within ~he accumula-tor. The hwdraulic pump used to operate the hydraulicram is efEectively idling during this phase of the jl~'J
cycle. In the case of the closed loop hydraulic system the pressurized hydraulic fluid from the cylinder is directed into the suction port oE the hydraulic pump which controls the movement of the fluid during the downstroke.
During the upstroke the fluid from the accumulator is fed to the hydraulic pump where the pressure is boosted and then supplied to the hydraulic cylinder. In another form of device the gas being compressed is contained in a dry accumulator (does not contain oil). The action of the falling rods causes a piston in the gas cyclinder to compress the gasO ~he oil from the hydraulic oil cylinder is directed to the suction port of the pump and is directed to atmospheric vented storage. The pump controls the downward movement of the piston. The pump does little or no work on the downstroke. The pressurized gas exerting upward pressure within the independent cylinder forces an independent piston, that is connected by the device to the hydraulic piston, upwardly and in this way augments the lifting force of the hydraulic motor system.
Accordingly the accumulator acts to counterbalance the weight of the reciprocating ~ods so that less work has to be carried out by the hydraulic pump during the upstroke action. Because the hydraulic pump operates at no load or partial load during the downstroke of the jack pump, only half or a reduced portion of the power available to the unit during the cycle of operation is made use of. As most power supply is charged for on a maximum-use basis this results in excess ca~ital costs and o~erating cllarges .
In the patents mentioned above the speed of the piston motor action is controlled directly by the capacity of the hydraulic pump~
Summary of the Invention It is an object of the present invention to make full .
use oE the hydraulic pump and power source equipment (energizing motor) throughout the complete cycle of operation of the hydraulic jack pumpO
It is a further object of the invention, at least in preferred forms, to incorporate an adjustable facility that allows for the accumulation of a portion of the energy by the pump assembly during the downs~roke of the pumping cycleO
According to one aspect of the invention there is provided a jack pump comprising: a reciprocating hydraulic motor having a power stroke and a dissipating stroke; a hydraulic pump having an inlet and an outlet for hydraulic fluid; at least one pressurized accumulator;
a reservoir for hydraulic fluid; and a hydraulic flow con-trol circuit interconnecting said motor, pump, accumulator and reservoir, said flow control circuit comprising: first pipe means interconnecting said reservoir and the inlet of said pump for enabling the pump to draw hydraulic fluid from said reservoir second pipe means directly connecting the outlet of said pump to said at least one pressurized accumulator so that hydraulic fluid may be pumped on a continuous basis to said at least one accumulator; third pipe means connecting said at least one accumulator to said hydraulic motor to enable pressurized hydraulic fluid to pass from said accumulator to said motor to cause said power stroke; fourth pipe means connecting said hydraulic motor to said reservoir to enable hydraulic fluid from said motor to pass directly to said reservoir during said dissipating stroke; sensor means to d~termine when said motor has terminated its power stroke and its dissipating stroke respectively; and valve means controlled by said sensor means and acting on sa.id third and fourth pipe means to permit pressurized fluid to pass through said third pipe means ~or said Power stroke and through said fourth pipe means during said dissinating stroke without restrictiny the flow of fluid through said ~irst and -4a-second pipe means caused by continuous operation of said pump.
According to another aspect of the invention there is provided a method of operating a jack pump including a reciprocating hydraulic motor having a power stroke and a dis.sipating stroke, at least one pressurized accumulator, a hydraulic pump, a reservoir for hydraulic fluid and a hydraulic flow circuit interconnecting said motor, pump, accumulator and reservoir; said me~hod comprising: operat-ing said pump ,continuously throughout each cycle comprising a power stroke and a dissipating stroke of said motor to continuously charge said pressurizedaccumulator with hydraulic fluid from said reservoir; directing fluid from said accumulator to said motor during said power stroke in order to actuate said motor; and directing fluid from said motor directly to said reservoir during said dissipating stroke.
In a preferred form of the invention, the reservoir is maintained under a superatmospheric pressure.
An advantage of the invention, at least in its preferred forms, is that it can utilize a minimum power source at a level rate of usage throughout the full cycle period and that it can conserve a reasonably large portion of the energy that is expended by the downward action of the sucker rods; this conserved or accumulated energy to be used in support of the hydraulic pump, reducing the power required to charge the power accumulators inter-posed between the hydraulic pump and the hydraulic motor. The invention can also provide a means of raising the sucker rods at a rate of speed greater than that which would be possible if the pump acted directly to supply the oil volume required to move the piston upwardly in ~he mo-tor, and ~rovldes a means of allowing the sucker rods to return to their lower position unimpeded by mechanical constraints inherent within the jack pump.
It is a further advantage of the present invention, at least in preferred forms, that it can divide the upstroke action and the downstroke action of the hydraulic jack pump in order to control and maximize independently the functions of lift (upstroke) and the function of freefall (downstroke)~
The described invention, at least in the pre-ferred forms, maximizes the speed of rise of the sucker rods consistent with the capacity of the oil-well e~uipment, and maximizes the rate of fall by a self-regulating system of the sucker rods consistent with the oilwell production characteristics, and conserves the maximum amount of expended energy during the downward movement of the sucker rods, the maximum being determined by the production characteristics of the oilwell; and further utilizes the power available on a 60 second per minute basis.
This invention is designed in particular to deal with and satisfy the very difficult production problems of heavy viscous oil production.
Heavy viscous oil is produced by different methods ranging from what is termed as primary production which, in so far as jack pumps are concerned, is the pumping of the oil by a conventional downhole pump without the assistance of pressurization of the formation or heating 3~ of the oil to cause it to be less viscous; to tertiary production systems which may involve pressurizing the formation reservoir and heating the oil in ~ . In order to maximize production it is necessary to raise the pump plunger as rapidly as possible consistent with downhole considerations and eqoipment constraints and then to allow , ,~
i i the sucker rods together with the pump plunger to return to the bottom position as rapidly as possibleO During a ter~iary pxoduction cycle that employs a method of heating the oil bear-ing formation, the oil originally produced is warm and flows reasonably freely. As the cycle proqresses to its final phase, the oil becomes cooler and more viscousO As the oil becomes more viscous the oil in the production tubing tends to restrict the action of the sucker rods when falling to their bottom posit:ion. This change in rate of speed is gradual and progresC;ive. In order to allow the pump to function to permit the return of the sucker rods to the lower position as rapidly as possible throughout the changing cycle, ;t is necessary to permit a maximum degree of freefall action. In one form of the invention later described this is accomplished by accumulating a maximum amount of the energy expended by the sucker rods returniny to the lower position consistent with allowing sufficient downward force due to gravity in order to cause the rods to fall at their maximum rate of fall. This form of the invention further allows the maximization of the above action by virtue of having the energy accumulation system pursuant to the upward thrust of the piston incorporated with;n the system in such a manner as to not restrict the freefall action of the rods in any way; and by virtue of having the downthrust energy accumulation system operate entirely independent of the upward thrust system which allows for independent regulation of the downward thrust energy accumulation~ makin~ it possible to use any portion of the rod fall energy to force the downward movement of the sucker rods within the shortest possible time. The time period will adjust automatically in accordance with the change in viscosity of the crude oil within the production column.
During the period of the downward movement of the sucker rods, the hydraulic pump forces oil into the 6~
:
accumulator positioned downstream from the hydraulic pump, recharging the oil volume that was allowed to move into the cylinder during the upstroke of the 3ack pump. During the upstroke period the hydraulic pump continues to charge the accumulator. This allows full cycle utilization of pump capacity and power provided.
The upstroke action is governed by the capacity of the accumulators positioned between the hydraulic pump and the cylinder to deliver pressurized fluid to the cylinder.
10 This is regulated independently from the pump's volume capacity. This technique maximizes the speed of the upstroke~ However, the volume of fluid supplied by the pump over a full cycle is equal to that required by the cylinder during the upstroke.
The system allows:
1. the maximum upward speed of the sucker rods that their design and other production considerations will permit;
2. the full use of the time involved in the downward movement of the rods to maximize the use of hydraulic pump and power supply capacity in the process of recharging the accumulators;
3. the freedom to maximize the downward movement of the sucker rods by allowing use of that amount of downward force that is required to move the rods to their lowest position as rapidly as possible; and
4. to conserve any energy generated by the freefall of the rods that is excessive to that force required to return the rods to their lowest position within the time frame dictated by production program considerations.
The accumulators as used in this present invention are rreferably of the closed chamber form. The charged gas can-not escape without a conscious action of bleeding off.
Description o~ the Drawings Figure 1 is a diagram of the hydraulic circuit of one ., .
~8--embodiment of the invention showing the operation during the start~p of the unit;
Figure 2 is a diagram of the same hydraulic circuit showing the operation during the upstroke of the cycle;
Figure 3 is a diagram of the same hydraulic circuit showing the operation during the downstroke of the cycle;
and Figure 4 is a perspective diagram showing various parts of the pump jack e~uipment used in the circuit of Figures 1-3 but omitting connecting tubing.
Description of the Preferred Embodiments Figures 1 to 3 shou the same hydraulic pumping unit, which is an embodiment of the present invention, in three different phases of operation, as described below.
The main parts of the hydraulic pumping unit are as follows. A cylinder 7 is mounted vertically above a well head (not shown). The cylinder contains a hydraulically activated piston 45 connected to a piston rod 46. The piston rod 46 is connected to a polish rod (not shown) at the well head, and the polish rod is in turn connected to sucker rods (not shown) connected to a pump at the bottom of the well. Repeated raising of the piston 45 in cylinder 7 by the pressure of hydraulic fluid under the piston, and lowering of the piston under the weight of the sucker rods, causes oil to be pumped from the well.
Hydraulic fluid is supplied through first pipe means ~line D) from a reservoir 28 to the inlet of pump 2 and thence through second pipe means to accumulators 3 for use in operating the piston 45. Third pipe means connect the accumulators 3 to the cylinder 7 and ~ourth pipe means connect the cylinder 7 to ~he reservoir 28. The flow of hydraulic fluid is governed by a cîrcuit which includes sensors in the Eorm of limit control valves 8 and 9 operated in turn by an actuator in the form of a projection 100 on piston rod 46. The drawings show a space between projection 100 and limit control valves ~ and 9 but in reality the limit control , . , ~
valves are of course positioned to contactl and thus to be operated by, ~he projection 100.
Figure 1 shows the start up procedure necessary for preparing the unit for normal operation. A predetermined
The accumulators as used in this present invention are rreferably of the closed chamber form. The charged gas can-not escape without a conscious action of bleeding off.
Description o~ the Drawings Figure 1 is a diagram of the hydraulic circuit of one ., .
~8--embodiment of the invention showing the operation during the start~p of the unit;
Figure 2 is a diagram of the same hydraulic circuit showing the operation during the upstroke of the cycle;
Figure 3 is a diagram of the same hydraulic circuit showing the operation during the downstroke of the cycle;
and Figure 4 is a perspective diagram showing various parts of the pump jack e~uipment used in the circuit of Figures 1-3 but omitting connecting tubing.
Description of the Preferred Embodiments Figures 1 to 3 shou the same hydraulic pumping unit, which is an embodiment of the present invention, in three different phases of operation, as described below.
The main parts of the hydraulic pumping unit are as follows. A cylinder 7 is mounted vertically above a well head (not shown). The cylinder contains a hydraulically activated piston 45 connected to a piston rod 46. The piston rod 46 is connected to a polish rod (not shown) at the well head, and the polish rod is in turn connected to sucker rods (not shown) connected to a pump at the bottom of the well. Repeated raising of the piston 45 in cylinder 7 by the pressure of hydraulic fluid under the piston, and lowering of the piston under the weight of the sucker rods, causes oil to be pumped from the well.
Hydraulic fluid is supplied through first pipe means ~line D) from a reservoir 28 to the inlet of pump 2 and thence through second pipe means to accumulators 3 for use in operating the piston 45. Third pipe means connect the accumulators 3 to the cylinder 7 and ~ourth pipe means connect the cylinder 7 to ~he reservoir 28. The flow of hydraulic fluid is governed by a cîrcuit which includes sensors in the Eorm of limit control valves 8 and 9 operated in turn by an actuator in the form of a projection 100 on piston rod 46. The drawings show a space between projection 100 and limit control valves ~ and 9 but in reality the limit control , . , ~
valves are of course positioned to contactl and thus to be operated by, ~he projection 100.
Figure 1 shows the start up procedure necessary for preparing the unit for normal operation. A predetermined
5 quantity of oil is charged to reservoir 28 and the reservoir 28 is charged with pressurized gas (e.g.
nitrogen3 to a minimum of 10 p.s.i. Gas is charged to accumulators 3 up to a p.s.i. equal to the amount of lifting pressure that is to be required below piston 45.
Low pressure acc~ulators 10 and 21 are charged with a suitable amount of gas. Valve 22 is closed. The projection 100 on the lower position of piston rod 46 impinges against a plunger of limit control valve 9O
Valve 9 will move to the open position as soon as pressurized fluid is received from line A~
Electric motor 1 is started causing variable speed hydraulic pump 2 to operate. Oil is drawn through first pipe means from reservoir 28 by the pump through valve 30 and filter 29, and the fluid is directed through second pipe means to accumulators 3 through check valve 37 and shutoff valves 38 and 39 that are in the open positions.
A pump discharge pressure of approximately 110% of the lifting pressure within cylinder 7 is employed. When this pressure is reached, the pump 2 pressure is main-tained by means of a pressure compensating device.
The operation of the pump 2 pressurizes lLne A causing fluid to flow through valve 9 Erom port P to B and thence to port A of valve 11. This opens valve 11 so that fluid flows from line A to valve 4, causing valve 4 to open.
Needle valve 23 is opened manually allowing fluid to pass through line E to a position within the cylinder 7 below piston 45. Pressurization of line E causes oil to flow to valve 5, thus opening valve 5. Valve 23 is now manually closed. Manual operation of valve 23 is required at this stage because, during initial startup, the total system is not pressurized. A predetermined amount of oil is let into accumulators 10 and 21 through valve 49. Valve 49 is then closed and the unit is ready for operation.
Figure 2 shows the operation of the unit during the upstroke. Valve 22 is opened sufficiently and acts as a flow control valveO Oil frc,m accumulators 3 is forced into line B, through valve 22 to cylinder 7 via vaLves 4, 5 and 6, (i.e. the third pipe means) causing the piston 45 ~o begin to rise to its uppermost position. The rate of rise oE the piston that is desired is converted into oil volume per second at a desired pressure adequate to lift the weight attached to piston rod 46. The desired rate of flow is set on valve 22. The desired pressure is set on the pump pressure control. The pump volume control is set to provide a volume of oil slightly in excess of that set on valve 22. Valve 4 is kept in the open position because of the pressurized fluid it receives from valve 11 which in turn is kept open by the pressurized ~luid it receives from valve 9. Valve 5 is kept open by the pressurized fluid it receives from line ~. The piston 45 continues to rise at the desired rate until projection 100 on piston rod 46 contacts a plunger of limit control valve 8.
Figure 3 shows the operation of the pumping unit during the downstroke. Depression of the plunger of limit control valve 8 by projection 100 causes oil to flow from line A to ports P and B and then to port B of valve 11.
Valve 11 then directs pressurized fluid from line A to valve 12, opening it. Valve 4 is vented through valve 11 to a sump reservoir 33 via valve 17, thus allowing valve 4 to assume the closed position. Valve 5 remains in the open position. Oil flows from cylinder 7 through line ~, through flow control valve 6, line C and valve 12 to the reservoir 28 (i.e. the fourth pipe means), Because of the gas pressure in reservoir 28, the weight ,, of the sucker rods attached to piston rod 46 is counter-balanced to some extent. The gas pressuxe is selected to be compatible with production characteristics and a normal setting is about one halE of the cylinder lifting pressure.
In the event that the restric:tions within the oil produc-tion column in the well are not adequate to retard the rate of downward movement of the sucker rods to a sufficient extent, the rate of downward movement can be controlled by valve 6. This valve can be adjusted manually.
Accumulators 10 and 21 together with needle control valves 13, 15, 17 and 19 serve the purpose of dampening the change in force at the top and bottom of the piston stroke.
Oil from the A piston of valve 11 can escape through valve 9 to be vented to tank 33. The small amount of bypass oil from pump 2 is vente~ into tank 33. Tank 33 ~lso receives oil from valves 5, 4, 12, 8 and 9 during operation of these valves. The pipes conveying the fluid to tank 33 act as Eifth pipe means~ The level of oil in tank 33 is controlled by float switch 31. when the switch is operated, oil is drawn from tank 33 by pump 34 oper-ated by electric motor 35 and transferred to reservoir 28 (through sixth pipe means). The pressure setting on pump 34 is controlled by pressure relief valve 36, which is set at a p.s.i. somewhat greater than the maximum in reservoir 28.
Valve 5 is an emergency control valve to shut off fluid to the cylinder. If the sucker rod attached to piston rod 46 should break, piston 45 would have free upward movement and the pressure within cylinder 7 would be rapidly reduced. Valve S is held in the open position by pressure from line E which has the same pressure as the fluid in the cylinder. If the pressure falls in line E, valve S closes~ shutting ofE the flow of oil to line E and the cylinder.
i. ~, During the period of discharge of oil from cylinder 7, i.e. the downstroke, the hydraulic pump 2 continues to draw oil from reservoir 28, pressurize it and charge it to accumulators 3, thus replenishing the charge of pressurized oil in the accumulators 3. Pump 2 operates continuously under load during the full cycle of operation of the pumping unit, thus putting the pump to maximum use for efficiency.
It can be seen that the rate at which the piston rises within the cylinder is determined by the load suspended from the piston rod, the pressure maintained in accumulators 3 and the amount of fluid that is allowed to pass through valve 22. For example, the gallons per minute of fluid that can be charged to cylinder 7 from the accumulators 3 can be considerably greater than the gallons per minute output of the pump. The pump can utilize the longer period of downstroke to recharge the accumulators 3 with sufficient hydraulic oil for the upstroke. For example, if t.he piston rises in 15 seconds and falls in 45 seconds, the system allows three times as long for the pump to accumulate the pressurized fluid in the accumulators, than is required for the discharge of the pr~ssurized oil from the accumulators. In this case, the power requirement of the motor 1 that operates pump 2 may be 1/3 of that required to raise the piston in a system employing a direct pump to cylinder connection. Thus by charging accumulators 3 with a pressure related to the lift required by piston 45, by setting valve 22 to minimize the period of the upstroke, and by setting the pump pressure and volume in proper relationship with the maximum pressure and volume required in accumulators 3, the action of the hydraulic pump can be set to use the minimum amount of power consistent with the time available (~ull cycle period) to adequately charge accumulators 3 to provide the necessary energy for raising the piston.
~,t,S'",~
-12a-The system also all.ows for flexible control of the downward action of the sucker rods when the fluidity of the produced oil is sufficlent to allow the sucker rods to fall freely, the rate of fall can be conkrolled by valve 6 and the restrictive pressure maintained ih reservoir 28.
It is necessary ~o leave sufficient difference between the pressure below the piston in the cylinder and the pressure within the reservoir 28 to permit as rapid a fall of the sucker rods as production conditions allow. The rate of rod all is governed by production constraints and not by i5~
limitations within the pumping unit structure, As was the case with the upstroke so it is with the case of the downstroke, i.e, the system allows for optimization of the respective movements. Both the upstroke and the down-stroke are dealt with as individual components of thetotal cycle. It is thus possible to balance the time ratios and ~he power factors within the widest possible ranges~
~eservoir 28 reclaims energy generated by the downward fall of the sucker rods that is not required to return the sucker rods to their lower position. The pressurized fluid from reservoir 28 is fed to the inlet of pump 2 where the pressure is further boosted for delivery to accumulators 3. The pressurization of the fluid in reservoir 28 thus reduces the power requirement of the pump for delivering pressuri~ed ~luid to the accumulators 3.
As an example, the pump pressure may be 2000 p.s.i.
and the pressure in the reservoir may be 1000 p.s.i~
Figure 4 show~ the various components of the equipment described in connection with Figures 1, 2 and 3, inter-connecting conduits having been omitted for the sake of clarity.
The accumulators 3, combined hydraulic pump 2 and motor 1, the oil accumulator reservoir 28 and a cooler 66 for the hydraulic fluid are mounted on a supporting plate 80.
The cylinder 7 containing the piStOIl 45 with dependent piston rod 46, is mounted on a triangular cage 81 formed by triangular end plates 82 and 83 separated by support rods 84, 85, and 86. The cage 81 is located above a well head, from which a polish rod 89 extends. The polish rod 89 is connected to the lower end of the piston rod 46 by a screw coupling 90. Projection 100 is located at the upper end of the polish rod (or alternatively at the lower end of the piston rod) for actuation of limit control valves 8 and g.
The pcsitions of limit controls 8 and 9 limit the length of the stroke of the piston 45 in the cylinder 7, since reversal of the piston takes place when the control 8 or 9 is actuated by the pro~ection 100. To enable the length of the stroke of ~he piston to be varied, the positions of the limit controls 8 and 9 are variable.
Each of these controls is slidably mounted on a vertical rod 91~ The rod is triangular in cross-section so that the limit controls 8 and 9 cannot rotate on the rod, but only move upwardly or downwardly. Vertical adjustment of the limit controls is controlled by a second vertical rod 92 extending through the limit control casings. This rod has an outer helical thread which engages with an internal thread (not shown~ in the limit control casings~ Rotation of the rod 92 in one direction or the other thus raises or lowers the limit controls 8 and 9. Rotation of the ro~ 92 can be controlled by a pulley arrangement 93.
The system of this invention allows the energy generated by the prime mover to be used at a uniform and steady rate throughout the full cycle of operation, by accumulating fluid under pressure during the full cycle period.
This is achieved by accumulating energy at an even rate throughout the full cycle period and using it for a portion of the cycle period that is less than 1/2 of the total cycle time.
Power requirements are further reduced by accumulating any surplus energy generated by the downward pull of the sucker rod and feeding this energy to the hydraulic pump on a continuous basis, thus augmenting the pump's action of storing energy in accumulators 3.
The above represents a preferred form of the invention.
,~.''~
..
Other forms of the invention falling within the scope of the following claims are possible, as will be apparent to a person skilled in the art. For example, resevoir 28 may be vented to the atmosphere so ~hat none of the energy of the free fall of the piston 45 together with the sucker rod string is recovered in reservoir 28 and by pass oil from the pump and regulating valves can be fed directly to reservoir 28 thus by-passing tank 33. This may be desir-able when no restriction on the free kall action of the 10 sucker rod string is requiredl. Further methods of counter balancing the weigh~ o~ the sucker rod string may be employed without affecting the basic action of this invention. This may be desirable when the diffeLence between the weight of the sucker rod s~ring and that of 15 the fluid column in the well is very great.
nitrogen3 to a minimum of 10 p.s.i. Gas is charged to accumulators 3 up to a p.s.i. equal to the amount of lifting pressure that is to be required below piston 45.
Low pressure acc~ulators 10 and 21 are charged with a suitable amount of gas. Valve 22 is closed. The projection 100 on the lower position of piston rod 46 impinges against a plunger of limit control valve 9O
Valve 9 will move to the open position as soon as pressurized fluid is received from line A~
Electric motor 1 is started causing variable speed hydraulic pump 2 to operate. Oil is drawn through first pipe means from reservoir 28 by the pump through valve 30 and filter 29, and the fluid is directed through second pipe means to accumulators 3 through check valve 37 and shutoff valves 38 and 39 that are in the open positions.
A pump discharge pressure of approximately 110% of the lifting pressure within cylinder 7 is employed. When this pressure is reached, the pump 2 pressure is main-tained by means of a pressure compensating device.
The operation of the pump 2 pressurizes lLne A causing fluid to flow through valve 9 Erom port P to B and thence to port A of valve 11. This opens valve 11 so that fluid flows from line A to valve 4, causing valve 4 to open.
Needle valve 23 is opened manually allowing fluid to pass through line E to a position within the cylinder 7 below piston 45. Pressurization of line E causes oil to flow to valve 5, thus opening valve 5. Valve 23 is now manually closed. Manual operation of valve 23 is required at this stage because, during initial startup, the total system is not pressurized. A predetermined amount of oil is let into accumulators 10 and 21 through valve 49. Valve 49 is then closed and the unit is ready for operation.
Figure 2 shows the operation of the unit during the upstroke. Valve 22 is opened sufficiently and acts as a flow control valveO Oil frc,m accumulators 3 is forced into line B, through valve 22 to cylinder 7 via vaLves 4, 5 and 6, (i.e. the third pipe means) causing the piston 45 ~o begin to rise to its uppermost position. The rate of rise oE the piston that is desired is converted into oil volume per second at a desired pressure adequate to lift the weight attached to piston rod 46. The desired rate of flow is set on valve 22. The desired pressure is set on the pump pressure control. The pump volume control is set to provide a volume of oil slightly in excess of that set on valve 22. Valve 4 is kept in the open position because of the pressurized fluid it receives from valve 11 which in turn is kept open by the pressurized ~luid it receives from valve 9. Valve 5 is kept open by the pressurized fluid it receives from line ~. The piston 45 continues to rise at the desired rate until projection 100 on piston rod 46 contacts a plunger of limit control valve 8.
Figure 3 shows the operation of the pumping unit during the downstroke. Depression of the plunger of limit control valve 8 by projection 100 causes oil to flow from line A to ports P and B and then to port B of valve 11.
Valve 11 then directs pressurized fluid from line A to valve 12, opening it. Valve 4 is vented through valve 11 to a sump reservoir 33 via valve 17, thus allowing valve 4 to assume the closed position. Valve 5 remains in the open position. Oil flows from cylinder 7 through line ~, through flow control valve 6, line C and valve 12 to the reservoir 28 (i.e. the fourth pipe means), Because of the gas pressure in reservoir 28, the weight ,, of the sucker rods attached to piston rod 46 is counter-balanced to some extent. The gas pressuxe is selected to be compatible with production characteristics and a normal setting is about one halE of the cylinder lifting pressure.
In the event that the restric:tions within the oil produc-tion column in the well are not adequate to retard the rate of downward movement of the sucker rods to a sufficient extent, the rate of downward movement can be controlled by valve 6. This valve can be adjusted manually.
Accumulators 10 and 21 together with needle control valves 13, 15, 17 and 19 serve the purpose of dampening the change in force at the top and bottom of the piston stroke.
Oil from the A piston of valve 11 can escape through valve 9 to be vented to tank 33. The small amount of bypass oil from pump 2 is vente~ into tank 33. Tank 33 ~lso receives oil from valves 5, 4, 12, 8 and 9 during operation of these valves. The pipes conveying the fluid to tank 33 act as Eifth pipe means~ The level of oil in tank 33 is controlled by float switch 31. when the switch is operated, oil is drawn from tank 33 by pump 34 oper-ated by electric motor 35 and transferred to reservoir 28 (through sixth pipe means). The pressure setting on pump 34 is controlled by pressure relief valve 36, which is set at a p.s.i. somewhat greater than the maximum in reservoir 28.
Valve 5 is an emergency control valve to shut off fluid to the cylinder. If the sucker rod attached to piston rod 46 should break, piston 45 would have free upward movement and the pressure within cylinder 7 would be rapidly reduced. Valve S is held in the open position by pressure from line E which has the same pressure as the fluid in the cylinder. If the pressure falls in line E, valve S closes~ shutting ofE the flow of oil to line E and the cylinder.
i. ~, During the period of discharge of oil from cylinder 7, i.e. the downstroke, the hydraulic pump 2 continues to draw oil from reservoir 28, pressurize it and charge it to accumulators 3, thus replenishing the charge of pressurized oil in the accumulators 3. Pump 2 operates continuously under load during the full cycle of operation of the pumping unit, thus putting the pump to maximum use for efficiency.
It can be seen that the rate at which the piston rises within the cylinder is determined by the load suspended from the piston rod, the pressure maintained in accumulators 3 and the amount of fluid that is allowed to pass through valve 22. For example, the gallons per minute of fluid that can be charged to cylinder 7 from the accumulators 3 can be considerably greater than the gallons per minute output of the pump. The pump can utilize the longer period of downstroke to recharge the accumulators 3 with sufficient hydraulic oil for the upstroke. For example, if t.he piston rises in 15 seconds and falls in 45 seconds, the system allows three times as long for the pump to accumulate the pressurized fluid in the accumulators, than is required for the discharge of the pr~ssurized oil from the accumulators. In this case, the power requirement of the motor 1 that operates pump 2 may be 1/3 of that required to raise the piston in a system employing a direct pump to cylinder connection. Thus by charging accumulators 3 with a pressure related to the lift required by piston 45, by setting valve 22 to minimize the period of the upstroke, and by setting the pump pressure and volume in proper relationship with the maximum pressure and volume required in accumulators 3, the action of the hydraulic pump can be set to use the minimum amount of power consistent with the time available (~ull cycle period) to adequately charge accumulators 3 to provide the necessary energy for raising the piston.
~,t,S'",~
-12a-The system also all.ows for flexible control of the downward action of the sucker rods when the fluidity of the produced oil is sufficlent to allow the sucker rods to fall freely, the rate of fall can be conkrolled by valve 6 and the restrictive pressure maintained ih reservoir 28.
It is necessary ~o leave sufficient difference between the pressure below the piston in the cylinder and the pressure within the reservoir 28 to permit as rapid a fall of the sucker rods as production conditions allow. The rate of rod all is governed by production constraints and not by i5~
limitations within the pumping unit structure, As was the case with the upstroke so it is with the case of the downstroke, i.e, the system allows for optimization of the respective movements. Both the upstroke and the down-stroke are dealt with as individual components of thetotal cycle. It is thus possible to balance the time ratios and ~he power factors within the widest possible ranges~
~eservoir 28 reclaims energy generated by the downward fall of the sucker rods that is not required to return the sucker rods to their lower position. The pressurized fluid from reservoir 28 is fed to the inlet of pump 2 where the pressure is further boosted for delivery to accumulators 3. The pressurization of the fluid in reservoir 28 thus reduces the power requirement of the pump for delivering pressuri~ed ~luid to the accumulators 3.
As an example, the pump pressure may be 2000 p.s.i.
and the pressure in the reservoir may be 1000 p.s.i~
Figure 4 show~ the various components of the equipment described in connection with Figures 1, 2 and 3, inter-connecting conduits having been omitted for the sake of clarity.
The accumulators 3, combined hydraulic pump 2 and motor 1, the oil accumulator reservoir 28 and a cooler 66 for the hydraulic fluid are mounted on a supporting plate 80.
The cylinder 7 containing the piStOIl 45 with dependent piston rod 46, is mounted on a triangular cage 81 formed by triangular end plates 82 and 83 separated by support rods 84, 85, and 86. The cage 81 is located above a well head, from which a polish rod 89 extends. The polish rod 89 is connected to the lower end of the piston rod 46 by a screw coupling 90. Projection 100 is located at the upper end of the polish rod (or alternatively at the lower end of the piston rod) for actuation of limit control valves 8 and g.
The pcsitions of limit controls 8 and 9 limit the length of the stroke of the piston 45 in the cylinder 7, since reversal of the piston takes place when the control 8 or 9 is actuated by the pro~ection 100. To enable the length of the stroke of ~he piston to be varied, the positions of the limit controls 8 and 9 are variable.
Each of these controls is slidably mounted on a vertical rod 91~ The rod is triangular in cross-section so that the limit controls 8 and 9 cannot rotate on the rod, but only move upwardly or downwardly. Vertical adjustment of the limit controls is controlled by a second vertical rod 92 extending through the limit control casings. This rod has an outer helical thread which engages with an internal thread (not shown~ in the limit control casings~ Rotation of the rod 92 in one direction or the other thus raises or lowers the limit controls 8 and 9. Rotation of the ro~ 92 can be controlled by a pulley arrangement 93.
The system of this invention allows the energy generated by the prime mover to be used at a uniform and steady rate throughout the full cycle of operation, by accumulating fluid under pressure during the full cycle period.
This is achieved by accumulating energy at an even rate throughout the full cycle period and using it for a portion of the cycle period that is less than 1/2 of the total cycle time.
Power requirements are further reduced by accumulating any surplus energy generated by the downward pull of the sucker rod and feeding this energy to the hydraulic pump on a continuous basis, thus augmenting the pump's action of storing energy in accumulators 3.
The above represents a preferred form of the invention.
,~.''~
..
Other forms of the invention falling within the scope of the following claims are possible, as will be apparent to a person skilled in the art. For example, resevoir 28 may be vented to the atmosphere so ~hat none of the energy of the free fall of the piston 45 together with the sucker rod string is recovered in reservoir 28 and by pass oil from the pump and regulating valves can be fed directly to reservoir 28 thus by-passing tank 33. This may be desir-able when no restriction on the free kall action of the 10 sucker rod string is requiredl. Further methods of counter balancing the weigh~ o~ the sucker rod string may be employed without affecting the basic action of this invention. This may be desirable when the diffeLence between the weight of the sucker rod s~ring and that of 15 the fluid column in the well is very great.
Claims (17)
1. A jack pump comprising:
a reciprocating hydraulic motor having a power stroke and a dissipating stroke;
a hydraulic pump having an inlet and an outlet for hydraulic fluid;
at least one pressurized accumulator;
a reservoir for hydraulic fluid; and a hydraulic flow control circuit interconnecting said motor, pump, accumulator and reservoir, said flow control circuit comprising:
first pipe means interconnecting said reservoir and the inlet of said pump for enabling the pump to draw hydraulic fluid from said reservoir;
second pipe means directly connecting the outlet of said pump to said at least one pressurized accumulator so that hydraulic fluid may be pumped on a continuous basis to said at least one accumulator;
third pipe means connecting said at least one accu-mulator to said hydraulic motor to enable pressurized hydraulic fluid to pass from said accumulator to said motor to cause said power stroke;
fourth pipe means connecting said hydraulic motor to said reservoir to enable hydraulic fluid from said motor to pass directly to said reservoir during said dissipating stroke;
sensor means to determine when said motor has terminated its power stroke and its dissipating stroke respectively;
and valve means controlled by said sensor means and acting on said third and fourth pipe means to permit pressurized fluid to pass through said third pipe means for said power stroke and through said fourth pipe means during said dissipating stroke without restricting the flow of fluid through said first and second pipe means caused by continuous operation of said pump.
a reciprocating hydraulic motor having a power stroke and a dissipating stroke;
a hydraulic pump having an inlet and an outlet for hydraulic fluid;
at least one pressurized accumulator;
a reservoir for hydraulic fluid; and a hydraulic flow control circuit interconnecting said motor, pump, accumulator and reservoir, said flow control circuit comprising:
first pipe means interconnecting said reservoir and the inlet of said pump for enabling the pump to draw hydraulic fluid from said reservoir;
second pipe means directly connecting the outlet of said pump to said at least one pressurized accumulator so that hydraulic fluid may be pumped on a continuous basis to said at least one accumulator;
third pipe means connecting said at least one accu-mulator to said hydraulic motor to enable pressurized hydraulic fluid to pass from said accumulator to said motor to cause said power stroke;
fourth pipe means connecting said hydraulic motor to said reservoir to enable hydraulic fluid from said motor to pass directly to said reservoir during said dissipating stroke;
sensor means to determine when said motor has terminated its power stroke and its dissipating stroke respectively;
and valve means controlled by said sensor means and acting on said third and fourth pipe means to permit pressurized fluid to pass through said third pipe means for said power stroke and through said fourth pipe means during said dissipating stroke without restricting the flow of fluid through said first and second pipe means caused by continuous operation of said pump.
2. A jack pump according to claim 1 wherein independent flow controls are provided in the third and fourth pipe means to enable the fluid flows through these pipe means during the power stroke and the dissipating stroke, respectively, to be independently adjusted.
3. A jack pump according to claim 1 wherein the reservoir contains a gas under pressure so that fluid from the motor on the dissipating stroke is charged to the reservoir under pressure, thus enabling pressurized fluid from the reservoir to be fed to the inlet of the pump to augment the pump's action of pressurizing the fluid and charging it to said at least one accumulator.
4. A jack pump according to claim 3 wherein the pressure in the reservoir is at least 10 p.s.i.
5. A jack pump according to claim 3 wherein the pressure in the reservoir is approximately one half the pressure required in the hydraulic motor to effect the power stroke.
6. A jack pump according to claim 1 wherein the pressure in said at least one accumulator is at least equal to the pressure required in the hydraulic motor to effect the power stroke.
7. A jack pump according to claim 1 wherein the pump is capable of generating a pressure of approximately 110% of the pressure required in the hydraulic motor to effect the power stroke.
8. A jack pump according to claim 1 further comprising at least one additional pressurized accumulator inter-connected with said flow control circuit to damp rapid changes in hydraulic pressure at the end of the power stroke and/or dissipating stroke.
9. A jack pump according to claim 1 further comprising a pressure sensitive valve in the hydraulic flow control circuit to shut off hydraulic fluid to the motor if the pressure therein falls abnormally quickly due to removal of a load on the jack pump.
10. A jack pump according to claim 1, wherein said motor has a piston, and said sensor means comprise limit controls for limiting the distance of travel of said piston during the power stroke and the dissipating stroke.
11. A jack pump according to claim 10, wherein said limit controls are adjustable so that said distance of travel may be varied.
12. A jack pump according to claim 11, wherein the motor has a piston rod attached to said piston, and said limit controls comprise an actuator on said piston rod and a pair of valves operable by said actuator, said valves being associated with said valve means to control the flow of pressurized fluid through said third and fourth pipe means.
13. A jack pump according to claim 12, wherein said valves are mounted on vertical rods of non-circular cross-section to permit vertical sliding but to prevent rotation, and wherein said valves are mounted on a further vertical rod of circular cross-section having a helical thread engag-ing with a thread of said valves, so that rotation of the threaded rods causes vertical sliding of the valves on the rods of non-circular cross-section.
14. A jack pump according to claim 3 further comprising an additional fluid reservoir vented to the atmosphere, fifth pipe means for conveying discharge fluid from said valve means and seepage fluid from said pump to said additional reservoir, sixth pipe means connecting the additional reservoir to the reservoir containing a gas under pres-sure, and additional pump means for conveying fluid along said sixth pipe means from said additional reservoir to the reservoir containing a gas under pressure.
15. A method of operating a jack pump including a recip-rocating hydraulic motor having a power stroke and a dissipating stroke, at least one pressurized accumulator, a hydraulic pump, a reservoir for hydraulic fluid and a hydraulic flow circuit interconnecting said motor, pump, accumulator and reservoir; said method comprising:
operating said pump continuously throughout each cycle comprising a power stroke and a dissipating stroke of said motor to continuously charge said pressurized accumulator with hydraulic fluid from said reservoir;
directing fluid from said accumulator to said motor during said power stroke in order to actuate said motor;
and directing fluid from said motor directly to said reservoir during said dissipating stroke.
operating said pump continuously throughout each cycle comprising a power stroke and a dissipating stroke of said motor to continuously charge said pressurized accumulator with hydraulic fluid from said reservoir;
directing fluid from said accumulator to said motor during said power stroke in order to actuate said motor;
and directing fluid from said motor directly to said reservoir during said dissipating stroke.
16. A method according to claim 15 which includes pres-surizing said reservoir so that, during said dissipating stroke, fluid from the motor is forced into said pres-surized reservoir to conserve at least some of the energy expended during the dissipating stroke.
17. A method according to claim 15 or claim 16 wherein said power stroke is operated for less than one half the total cycle time.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000405100A CA1196547A (en) | 1982-06-14 | 1982-06-14 | Hydraulic oil pump |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000405100A CA1196547A (en) | 1982-06-14 | 1982-06-14 | Hydraulic oil pump |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1196547A true CA1196547A (en) | 1985-11-12 |
Family
ID=4122999
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000405100A Expired CA1196547A (en) | 1982-06-14 | 1982-06-14 | Hydraulic oil pump |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1196547A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101915231A (en) * | 2010-07-23 | 2010-12-15 | 邯郸新兴重型机械有限公司 | Control method of variable-frequency hydraulic oil pump |
| CN111677705A (en) * | 2020-07-31 | 2020-09-18 | 山东巨能液压机械有限公司 | Hydraulic pumping unit with hydraulic control system |
| CN115256568A (en) * | 2022-08-17 | 2022-11-01 | 崇左广林迪芬新材料科技有限公司 | Heat conduction oil system of continuous flat-pressing plywood production line |
-
1982
- 1982-06-14 CA CA000405100A patent/CA1196547A/en not_active Expired
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101915231A (en) * | 2010-07-23 | 2010-12-15 | 邯郸新兴重型机械有限公司 | Control method of variable-frequency hydraulic oil pump |
| CN111677705A (en) * | 2020-07-31 | 2020-09-18 | 山东巨能液压机械有限公司 | Hydraulic pumping unit with hydraulic control system |
| CN115256568A (en) * | 2022-08-17 | 2022-11-01 | 崇左广林迪芬新材料科技有限公司 | Heat conduction oil system of continuous flat-pressing plywood production line |
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