OIL-PUMPING MACHINE

TECHNICAL FIELD

The disclosure relates to the field of oil-pumping machine, and particularly to a wheel-cylinder type oil-pumping machine.

BACKGROUND OF THE INVENTION

The beam crank-balanced pumping unit is widely used in extracting oil from a non-flowing well. With a history of one hundred years, this way of oil pumping has high electrical energy consumption, low operational efficiency, great mechanical impact force, and high cement and steel consumption. To reduce oil extraction costs, energy conservation and emission reduction has become major topics on how to improve efficiency in the oil extraction industry of the world.

Chinese patent application No. 200310100186.X discloses an oil pumping and workover unit comprising a head sheave shaft, a speed reducer, a gear, a pinion, an electric motor, a hoist rope of a head sheave, a balance weight, a balance weight carriage, a guide wire rope, a oil pumping polished rod, a main frame, a support platform and a head sheave (traction wheel), wherein the gear and the head sheave are fixed together and mounted on the head sheave shaft through a head sheave bearing, and a head sheave shaft fastener is used to fix the head sheave shaft on the support platform, or alternatively the gear and the head sheave are mutually fastened with the head sheave shaft, with both ends of the head sheave shaft fixed by a bearing on the support platform on which the speed reducer, the electric motor, a brake and an overload protector are mounted. The support platform is fixed on the top of the main frame. An oil pumping rod eye at one end is connected to the oil pumping rod and at the other end connected to the head sheave shaft through a traction rope for the oil pumping rod eye. The balance weight is fixed on the circumference of the head sheave via the balance weight carriage, the rod eye and the balance weight traction rope. The electric motor couples to the speed reducer through a brake and a coupler. The output shaft of the speed reducer couples to the pinion that meshes with the gear. Compared with the beam crank-balanced pumping unit, this new oil pumping and workover unit improves gross efficiency significantly and meantime to some extent functions as a workover rig. However, a professional workover rig may be still required for accomplishing some complicated workover. In this case, the head sheave and some components positioned above the oil pumping rod have to be displaced integrally, which causes a lot of inconvenience. In addition, as the oil pumping and workover unit needs to function as a workover rig, some components, such as electric motor and transmission device need to be modified accordingly.

Chinese patent application No. 03102663.X discloses a double-drive oil-pumping machine, wherein a support on its top has one or more upper guide sheave and at its bottom has a lower guide sheave. The upper guide sheave is fixedly mount on the support, and the upper guide sheave on the side of the support is occupied the space above an oil pumping rod, such that during workover the upper guide sheave must be dismantled to leave the space above the oil pumping rod. Typically, the dismantlement of the guide sheave is time and energy consuming. In some circumstance, even if the upper guide sheave were disassembled, it is still difficult to make room for the workover, and therefore the entire oil-pumping machine needs to be moved away during workover.

The co-assigned Chinese patent application No. 200710063926.5 submitted on Feb. 14, 2007 discloses an oil-pumping machine comprising a dividable guide sheave. When workover is needed, one can manually pull a support of the guide sheave to rotate around an axis in parallel to an oil pumping rod, thereby moving the guide sheave leaving the space above the oil pumping rod to make room for the workover. For this oil-pumping machine, the support of the guide sheave needs to be manually pulled. In addition, the oil-pumping machine has other shortcomings, such as large volume of secondary sheave and low reverse smoothness.

Furthermore, the existing oil-pumping machines are generally driven by friction and external gear mesh. Friction driving is prone to slip and has low efficiency. Gear mesh driving results in high wear and has a stress concentration per unit area and a large occupied space.

Therefore, there is a need for an oil-pumping machine that is easy to maintain, runs stably and has a compact structure. Moreover, there is a need for an oil-pumping machine that is expected to reduce energy consumption and can take the advantages of utilizing clean energies.

SUMMARY OF THE INVENTION

An Object of the disclosure is to provide a modified oil-pumping machine that costs low in oil extraction, has remarkable energy-saving effects and features a compact structure and simple maintenance.

An oil-pumping machine comprises a main frame, a oil pumping rod, a balance weight, a platform disposed on top of the main frame, and an electric motor, a guide sheave and a secondary sheave that are disposed on the platform, wherein the electric motor is configured to drive the secondary sheave to rotate about longitudinal axis thereof, and the secondary sheave comprises a left and right halves disposed along the axis. The circumference of the secondary sheave is provided with 2×n first holes, with the respective n first holes arranged on the left half and right half respectively. A balance weight traction rope extends from each of the first holes respectively and is connected to a fastener on the balance weight to constitute a balance weight operation and traction system. The circumference of the secondary sheave is further provided with 2×n second holes, with the respective n second holes arranged on the left and right halves respectively. An oil pumping rod suspension rope extends from each of the second holes respectively and is connected to the oil pumping rod through the guide sheave via a tractor to constitute an oil pumping rod operation and traction system. 2×m circles of spiral grooves are formed around the circumference of the secondary sheave, n and m being natural numbers and m>n, wherein the m circles of the spiral grooves are disposed on the left half while the other m circles of the spiral grooves are disposed on the right half, and the spiral grooves on the left half has a spiral direction opposite to that of the spiral grooves on the right half. The first holes and the second holes are arranged within the spiral grooves in a spaced manner such that at least part of the spiral grooves is shared by both the oil pumping rod suspension rope and the balance weight traction rope during operation, and thus the oil pumping rod suspension rope and the balance weight traction rope, in opposite directions, wind around or unwind from the at least part of the spiral grooves without interfering with each other. Preferably, each of the first holes and the adjacent second hole are configured such that at least part of the spiral grooves extending therebetween is shared by the oil pumping rod suspension rope and the balance weight traction rope extending therefrom. Consequently, the secondary sheave has a narrow width, and the electric motor acts only to change the directions of an up-and-down reciprocating movement of the oil pumping rod and the balance weight under gravity and to overcome the friction between the circumference of the wheel-cylinder type secondary sheave and the surface of wire rope, greatly increasing the energy efficiency. Moreover, the narrow width of the secondary sheave can adapt well to the existing width of the balance weight. In addition, the oil pumping rod suspension rope and the balance weight traction rope always run in a direction opposite to the moment of the secondary sheave.

According to a preferred embodiment of the disclosure, the first and second holes are alternately arranged on the left half and/or right half along the axial direction. Preferably, the 2×n first and/or second holes are arranged along a straight line parallel to the longitudinal axis in a spaced manner, and more preferably, the 2×n first and/or second holes are symmetrical with respect to a horizontal centre line.

According to a further preferred embodiment, the first and second holes are offset from each other at an angle of α of 110°-145°, e.g. 120°, around the circumference of the secondary sheave. Moreover, the number of circles formed by the oil pumping rod suspension rope and the balance weight traction rope in the spiral grooves is determined by the stroke of the oil-pumping machine and the diameter of the secondary sheave. For instance, in the event that the stroke of the oil-pumping machine is 8 meters, n=2 and m=8, that is, the secondary sheave is provided with four first holes for the balance weight traction rope and four second holes for the oil pumping rod suspension rope with 16 circles of the spiral grooves, wherein 8 circles of the spiral grooves are arranged on the left half of the circumference of the secondary sheave with left hand spiral, and the other 8 circles are arranged on the right half with right hand spiral. However, it also falls within the scope of the disclosure that the 8 circles of the spiral grooves are arranged on the left half with right hand spiral and the other 8 circles are arranged on the right half with left hand spiral. The winding length of the oil pumping rod suspension rope and the balance weight traction rope in the spiral grooves during operation is longer than the stroke of the oil-pumping machine. Preferably, during the operation of the oil-pumping machine, at least part of the balance weight traction rope still winds around the spiral grooves at a top dead center of the stroke of the oil-pumping machine, and at least part of the oil pumping rod suspension rope still winds around the spiral grooves at a bottom dead center of the stroke of the oil-pumping machine. In installation, the oil pumping rod suspension rope and the balance weight traction rope are configured such that, for example when the oil pumping rod suspension rope winds around the entire span of the spiral grooves extending between the first hole and the adjacent second hole, the balance weight traction rope completely leaves the spiral grooves, or vice versa.

In the abovementioned embodiment, four balance weight traction ropes extending from four first holes can be formed by one single main rope. One end of the main rope is fastened in a first one of the four first holes closest to the secondary sheave via an adjustable fastener. The other end of the main rope extends from the first one of the first holes, then into the secondary sheave through a second one of the first holes that is next to the first one, then out of the secondary sheave through a third one of the first holes that is next to the second one, and then into the secondary sheave through a fourth one of the first hole that is next to the third one, and then is fastened herein via an adjustable fastener, thereby forming four balance weight traction ropes of equal length. The balance weight traction ropes are arranged such that they can easily self adjust the tension of each traction rope per se during long-term operation. With a movable block adjuster arranged along the rope, the main rope is capable of correcting and adjusting looseness itself. Similarly, four oil pumping rod suspension ropes can also be formed by one single main rope. It could be conceivable that other numbers of the balance weight traction ropes and the oil pumping rod suspension ropes are applicable.

According to a preferred embodiment of the disclosure, a flat spiral spring arrangement is mounted at two ends in the interior of the secondary sheave respectively, and the two flat spiral spring arrangements have different spiral directions from each other. When the oil-pumping machine is at the highest or lowest point of the stroke, only one of flat spiral spring arrangements is in an energy storage mode, wherein the extensible length of the springs is greater than the stroke of the oil pumping rod, such that the inertia upon reversal of the secondary sheave is limited by damping. Such flat spiral springs can eliminate collision caused by mechanical reversal impact during internal gear mesh, reduce wear of both of tooth surfaces, alleviate inertia and impact caused by simultaneous mechanical reversal of the electric motor and the secondary sheave, and thereby achieve smooth mechanical reversal.

According to a further embodiment of the disclosure, the oil-pumping machine also comprises a guide sheave support with one end pivotally mounted on the platform and with another end, as a cantilever, extending beyond the platform and provided with the guide sheave. The guide sheave support and the guide sheave are driven to pivot upwardly with respect to the platform in a plane perpendicular to the plane of the platform by means of the rotation of the secondary sheave. In an aspect, a connection mechanism is provided for releasably connecting the guide sheave support to a main body of the secondary sheave when the oil pumping rod suspension rope needs to detach from the oil pumping rod to pivot the guide sheave upwardly. The connection mechanism comprises a first connection portion on the guide sheave support, a second connection portion on the secondary sheave, and a connection cable that releasably connects the first and second connection portions to each other. When the secondary sheave rotates, the connection cable pulls the guide sheave support and thus the guide sheave to pivot upwardly. As an alternative, the connection mechanism comprises, instead of the connection cable, a connection portion on the guide sheave support for releasably mounting the oil pumping rod suspension rope on the guide sheave support in the event that the guide shave needs to pivot upwardly, such that when the secondary sheave rotates, the oil pumping rod suspension rope pulls the guide sheave support and thus the guide sheave to pivot upwardly. Consequently, during workover, after an operation tractor of workover rig is equipped on top of the oil pumping rod, the electric motor drives the secondary sheave to make the guide sheave pivot upwardly, such that the tractor of the oil-pumping machine and the oil pumping rod suspension rope are pulled backwards together in grooves of the guide sheave to an erected position, where the guide sheave is in a workover position. Consequently, it can easily make room for workover without any manual operation and facilitate a safe operation. Preferably, there is a workover setting mode on a control panel of a control system, so as to achieve highly automatic workover.

Preferably, the oil-pumping machine of the disclosure also comprises a positioning tab arranged adjacent to the oil pumping rod on the platform and for adjusting and positioning the guide sheave. The positioning tab is configured to cooperate with a recess on the guide sheave support to position the guide sheave and adjust the elevation angle between the guide sheave and the platform. Consequently, when the workover is finished, the guide sheave can accurately return to a lower position. In this case, the positioning tab for adjusting and positioning the guide sheave is in form of two bolts screwedly mounted on two sides of the platform. The recess is in form of a groove on two sides of the guide sheave support. The elevation angle of the guide sheave is adjustable by screwing the bolts, which facilitates upward pivoting of the guide sheave. In accordance with a preferred embodiment of the disclosure, the elevation angle is 6°-12°. A fine adjustment of fore and aft positions of the guide sheave relative to the wellhead can be achieved also by adjusting the elevation angle. Besides, the cooperation between the positioning tab for adjusting and positioning the guide sheave and the recess under the tab can further prevent the guide sheave from offset leftwards or rightwards, and thereby improve stability of the structure.

In the disclosure, the main frame of oil-pumping machine is configured as a vertical sleeve, which comprises a vertical sleeve cavity, a gate, an electric control cabinet for controlling the electric motor arranged within the vertical sleeve cavity. The balance weight and the traction rope thereof extend into the vertical sleeve cavity. The height of the vertical-cylinder main frame depends on the displacement of the stroke of the oil pumping rod during pumping. With regard to the thickness of steel material used for the vertical-cylinder main frame, enhancement of rigidity of the frame shall be taken into consideration. The electric control cabinet is positioned on the backside of the main frame gate under indoor working condition.

Such an arrangement improves the current electric control cabinets in outdoor working condition and enhances safety and anti-theft security. It is advantageous in that the control panel of the electric control cabinet is positioned externally onto the gate at operator's eye level, so as to facilitate an operator's manipulation. According to an aspect of the disclosure, the secondary sheave at at least one end, preferably one end of interior cylinder thereof, has an annular gear which meshes with an output gear shaft of a multi-stage speed reducer. An input end of the multi-stage speed reducer couples to the output shaft of the electric motor through a coupler. The internal gear mesh transmission between the annular gear and the output gear shaft has a similar effect in rigidity, strength and reliability as compared to traditional beam-pumping units, and meanwhile it improves mechanical structure of traditional external gear transmission and work conditions of transmission system and makes maintenance easier. Furthermore, incorporating with the annular gear at one end of the wheel-cylinder secondary sheave not only reduces the size of the device and the force of rotational inertia, but also saves the cost greatly. Moreover, use of the wheel-cylinder type secondary sheave in the disclosure enhances control of revolution of the machine during reversing of the electric motor, improves overall performance of the electric motor and the controller, and allows matched operation.

Alternatively, the electric motor couples to and drives the secondary sheave by means of the transmission in form of a planetary gearing mechanism. For instance, the annular gear is similarly configured, and a sun gear, a planet gear, a planet carrier or the like may be further provided, in replace of the speed reducer.

Compared with the external gear having a traditional ratio of 1:1, the above-mentioned arrangement has a significantly increased gear ratio between the annular gear and the output gear shaft, such as of 1:2.5. Preferably, the planetary gearing shift mechanism has a gear ratio of more than 5, such that a transmission ratio is optimized. Consequently, the mechanical torque of transmission is increased, and rigidity of the transmission mechanism is improved. Moreover, the input end of the multi-stage speed reducer couples to the output shaft of the electric motor through a coupler. A power-off brake disc is positioned between the coupler and the input end of the multi-stage speed reducer, forming both mechanical and electrical driving system. The transmission mechanism can be simplified by omitting a traditional gearbox and transmission shaft thereof, so as to allow the transmission with gear teeth but without transmission shaft. Furthermore, the sun gear, planet gear and planet carrier are all positioned inside the cylinder body of the secondary sheave, which leads to a more compact transmission system.

At the time of light load, the electric motor may directly couple to and drive the secondary sheave.

In the disclosure, with an aim to effectively make use of wind energy in the nature, the oil-pumping machine is provided with a wind power system comprising wind generator, a fan controller and a storage battery which are connected to each other in sequence. The storage battery is connected to a control and management system of the oil-pumping machine through an inverter, wherein the wind generator is arranged on the platform on top of the main frame, and the storage battery is mounted within the balance weight.

In another aspect of the disclosure, with an aim to take advantage of the solar energy in the nature, the oil-pumping machine is provided with a solar energy generating system comprising a photovoltaic module, a photovoltaic controller and a storage battery which are connected to each in sequence. The storage battery is connected to the control and management system of the oil-pumping machine through an inverter.

In another aspect of the disclosure, the oil-pumping machine is provided with both a wind power system and a luminous energy power system. The wind power system comprises wind generator, a fan controller and a storage battery which are connected to each other in sequence, wherein the storage battery is connected to the control management system of the oil-pumping machine through an inverter. The solar energy generating system comprises a photovoltaic module connected to the storage battery, wherein a photovoltaic controller is provided between the photovoltaic module and the storage battery.

In addition, the balance weight operation and traction system is configured to have a slightly lighter balance weight than the weight of the oil pumping rod operation and traction system. During normal operation of the oil-pumping machine, the current difference between the forward and reverse running of the electric motor is preferably in range of 1-2 ampere.

The disclosure also provides various control systems for the oil-pumping machine, which can realize flexible reverse through cooperation of the mechanical mechanism and electric motor, reduce impact on the mechanical components, and increase strength and durability of the mechanical mechanism, electric motor and controller during long-term running.

BRIEF DESCRIPTION OF THE DRAWINGS

The complete and enable disclosure of the present invention includes a best mode to those skilled in the art, which will be further described below in detail in conjunction with the accompanying drawings, wherein:

FIG. 1 is a side view of an embodiment of the oil-pumping machine according to the invention, showing the guide sheave in operation and workover positions;

FIG. 2 is a side view of the oil-pumping machine as shown in FIG. 1 in operation position;

FIG. 3 is a front view of the oil-pumping machine as shown in FIG. 1;

FIG. 4 is a schematic view of the flat spiral spring positioned inside the secondary sheave;

FIG. 5 is a schematic view of the oil pumping rod suspension rope almost completely winding around the secondary sheave;

FIG. 6 is a schematic view of the balance weight traction rope almost completely winding around the secondary sheave;

FIG. 7 is a top view of the working platform of the oil-pumping machine as shown in FIG. 1;

FIG. 8 is a schematic view of the position relation among the oil pumping rod suspension rope, balance weight traction rope, guide sheave and secondary sheave;

FIGS. 9
a and 9b schematically shows an arrangement of the oil pumping rod suspension rope and balance weight traction rope winding around the spiral grooves in another embodiment of the present invention;

FIG. 9
c is a schematically side view of FIGS. 9a and 9b, showing two opposite directions of the secondary sheaves respectively for upward and downward strokes of the oil pumping rod;

FIG. 10
a shows a curve regarding direction reverse of the electric motor output shaft the when the induction motor is out of control;

FIG. 10
b shows a curve regarding direction reverse of the secondary sheave when the induction motor is out of control;

FIG. 10
c shows a curve regarding the physical properties of direction reverse of mesh engagement between the transmission output gear shaft and the internal gear of the secondary sheave cylinder when the induction motor is out of control;

FIG. 11
a shows a curve regarding physical properties of the flat spiral springs within the secondary sheave cylinder, wherein forward and reverse forces are generated simultaneously;

FIG. 11
b shows the electrical damping properties at the time of direction reverse of the output shaft when the induction motor and permanent magnet synchronous motor are under control;

FIG. 11
c is a graphic showing the comparison between the working conditions curves of the oil-pumping machine in the disclosure and of the known beam-pumping unit;

FIG. 12 schematically shows operation control of upward and downward speeds V1 and V2 in the strokes D of the oil pumping rod by means of the control system according to the present invention;

FIG. 13 is a side view of another embodiment of the oil-pumping machine according to the present invention, showing operation and workover positions of the guide sheave;

FIG. 14 is a side view of the oil-pumping machine as shown in FIG. 13 during operation;

FIG. 15
a is a top view of the working platform of the oil-pumping machine as shown in FIG. 13;

FIGS. 15
b and 15c show the electric motor and the transmission respectively;

FIG. 16 is a schematic view of another embodiment of the oil-pumping machine, as shown on FIG. 13, with a wind power system and luminous energy power system;

FIG. 17 is a schematic view showing an arrangement of the wind power system and luminous energy power system in the oil-pumping machine according to the present invention;

FIG. 18 is a schematic view of the planetary gearing transmission mechanism and flat spiral springs arranged within the secondary sheave.

LIST OF REFERENCE SIGNS

1—oil pumping rod, 2—oil pumping rod suspension rope, 3—tractor, 4—guide sheave, 5—wheel-cylinder type secondary sheave (secondary sheave), 5a—first hole, 5b—second hole, 6—transmission, 6a—sun gear, 6b—planet gear, 6c—planet carrier, 6e—electromagnetic brake, 7—annular gear, 8—top support platform, 9—vertical sleeve type main frame, 10—balance weight traction rope, 11—balance weight, 11′—fixing and guiding rope, 12—control cabinet, 13—flat spiral spring, 14—gate of electric control cabinet, 15—secondary sheave support, 16—fastener for balance weight traction rope, 17—fastening hole for balance weight traction rope, 18—output shaft of multi-stage speed reducer, 19—secondary sheave shaft, 20—support for guide sheave, 21—guide sheave bearing, 22—positioning tab for adjusting and positioning guide sheave, 24—fixing and adjusting unit, 106—multi-stage speed reducer, 26—brake, 27—electric motor, 28—coupler, 29—spiral groove, 30—top platform sealing cover, 114—control panel, 115—guide cable, 116—storage battery, 117—photovoltaic module, 118—stop mechanism for horizontal rotation of the fan, 123—wind generator, 124—wind wheel, 125—fan controller, 126—inverter, 128—fan cabin, 129—photovoltaic controller, and 31—control, management and drive system of oil-pumping machine.

DESCRIPTION OF DETAILED EMBODIMENTS

Referring now to the following discussion in connection with the accompanying drawings, illustrative embodiments of the disclosure are described in detail. It is conceivable by those skilled in the art that although the drawings represent some possible features of the disclosure, the drawings are not necessarily to precisely scale and certain features may be exaggerated, sectioned or removed to better illustrate or explain the present disclosure.

FIGS. 1-3 show a preferred embodiment of the oil-pumping machine in the invention. As shown in FIG. 1, the cylinder-type oil-pumping machine of the invention mainly comprises a vertical sleeve type main frame 9, a oil pumping rod 1, a balance weight 11, a platform 8 on top of the main frame, and an electric motor 27, a multi-stage speed reducer 106, a guide sheave 4 extending beyond the platform as an cantilever and a secondary sheave 5 supported by a secondary sheave support 15 on the platform 8. Preferably, a top platform sealing cover 30 is mounted on the platform 8 to prevent from exterior influence. The electric motor couples to and drives the secondary sheave 5 through the multi-stage speed reducer 106. However, the electric motor can directly (e.g., under light load) or via other means indirectly couple to and drive the secondary sheave to rotate about its longitudinal axis, as further described below. In the embodiment, the main frame 9 comprises a vertical sleeve type cavity, within which a control cabinet 12 for controlling the electric motor is positioned and into which the balance weight 11 and the balance weight traction rope 10 extend, and a gate 14. It is conceivable by those skilled in the art that the height of the vertical sleeve type main frame 9 depends on the displacement of the stroke during pumping. The steel materials for vertical sleeve type main frame are selected to strengthen the rigidity of the derrick. The electric control cabinet 12 is arranged on the backside of the gate 14 under an indoor working condition. This improves the outdoor working condition of the current control cabinet and enhances safety and anti-theft security. Advantageously, a control panel of the control cabinet positioned externally onto the gate at operator's eye level, so as to facilitate manipulation.

In a more preferred embodiment, in order to reduce the height of the vertical sleeve type main frame 9, a recess is arranged within the vertical sleeve type cavity below the balance weight, which allows the balance weight 11 to extend into the recess during downward running. Therefore, without a change in the stroke of the oil pumping rod, the height of the vertical sleeve type main frame 9 can be decreased to some extent.

In the disclosure, the secondary sheave is configured such that an oil pumping rod suspension rope and a balance weight traction rope can fully wind around the cylinder-type secondary sheave respectively, as schematically shown in FIGS. 5 and 6. For clarity, the balance weight traction rope is omitted in FIG. 5, so is the oil pumping rod suspension rope in FIG. 6. The solid lines in FIGS. 5 and 6 refer to the suspension rope or traction rope and the dashed lines represent the spiral grooves that are not occupied by the suspension rope or traction rope. To show that the suspension rope or traction rope in FIGS. 5 and 6 are overhanging, the secondary sheave 5 in FIG. 5 or 6 is, for example, seen from the front or back of the oil-pumping machine. However, it can be understood by those skilled in the art that the winding configuration of the suspension rope or traction rope is schematically illustrated, to which the present invention is not intended to be limited. For instance, the first or second holes can be in other positions and the suspension rope or traction rope winds in more or less coils. Complete winding of the suspension rope or traction rope means that the balance weight traction rope or the oil pumping rod suspension rope respectively winds around the secondary sheave to the greatest extent when the oil pumping rod is on the top and bottom dead center of the stroke. As illustratively shown in FIG. 5, for example, the secondary sheave has a diameter of 1 meter and a stroke of 8 meters, and then the circumference of the secondary sheave 5S is provided with 2×n (=4) second holes 5b that are arranged in a spaced manner along a straight line parallel to the longitudinal axis of the secondary sheave, with two left and right second holes symmetrically situated on the left and right side of the secondary sheave, respectively. An oil pumping rod suspension rope 2 extends from each of the second holes 5b respectively, goes around the guide sheave 4 and then is connected to the oil pumping rod 1 via a tractor 3, which constitutes an operation and traction system for the oil suspension rod. As shown in FIG. 5 to 7, the circumference of the cylinder-type secondary sheave 5 is provided with 2×n (=4) first holes 5a that are arranged in a spaced manner along a straight line parallel to the longitudinal axis of the secondary sheave, with two first left and right holes situated on the left and right respectively. A balance weight traction rope 10 extends from each of the first holes 5a respectively, and is connected to a fastener 16 for the balance weight traction rope arranged on the balance weight 1 via a fastening hole 17 (FIG. 6) for the balance weight traction rope, which constitutes an operation and traction system for the balance weight traction rope. In the illustrated embodiment, the four second holes 5b for the oil pumping rod suspension rope 2 are closer to the center of the secondary sheave than the four first holes 5a for the balance weight traction rope 10. Nevertheless, the four first holes 5a may be closer to the center of the secondary sheave than the four second holes 5b, which is also within the protection scope of the invention.

In the embodiment shown in FIGS. 5 and 6, the secondary sheave 5 comprises 2×m (=16) circles of spiral grooves 29 around its circumference, with 8 circles of spiral grooves on the left portion of the secondary sheave 5 having left hand spiral and the rest 8 circles of spiral grooves on the right portion having right hand spiral. Four first holes 5a are arranged in the four out of the 16 circles of spiral grooves, correspondingly, while four second holes 5b in another four circles of the 16 circles of spiral grooves. As a result, four balance weight traction ropes 10 extending from the first holes 5a and four oil pumping rod suspension ropes 2 extending from the second holes 5b wind around and are received in the corresponding spiral grooves in the opposite direction during the operation of the oil-pumping machine, without interference with each other, i.e., they wind around or unwind from the secondary sheave without interference with each other. That is to say, the spiral grooves 29 on the secondary sheave 5 are shared by a group of balance weight traction ropes 10 and a group of oil pumping rod suspension ropes 2. When the traction ropes leave the spiral grooves, the suspension ropes wind around and occupy the corresponding spiral grooves, thereby causing no interference with each other. Specifically, in embodiment as shown in FIGS. 5-7, part of the spiral grooves extending between each first hole and the adjacent second hole are shared by the oil pumping rod suspension rope 2 and the balance weight traction rope 10 extending from said holes during the operation of the oil-pumping machine. For instance, as shown in FIGS. 5 and 6, as the secondary sheave 5 rotates from a complete winding configuration of the oil pumping rod suspension rope (FIG. 5) to complete leaving configuration of the suspension rope (FIG. 6), the balance weight traction rope accordingly begins to wind around and then completely wind around the secondary sheave. The concept of winding will be described below with reference to FIG. 9a-9c. The oil pumping rod suspension rope 2 and the balance weight traction rope 10 are designed such that when one of the oil pumping rod suspension rope 2 and the balance weight traction rope 10 completely winds around the spiral grooves extending between the first hole and the adjacent second hole (preferably, the length of ropes are substantively equal to or slightly longer than the length of the spiral grooves), then the other completely leaves the spiral grooves. Moreover, as shown in FIGS. 5 and 6, at least part of the balance weight traction rope still winds around the spiral grooves (in FIG. 6, showing the complete winding of the balance weight traction rope 10) when the oil-pumping machine is at the top dead center of the stroke, so does part of the oil pumping rod suspension rope (in FIG. 5, showing the complete winding of the oil pumping rod suspension rope 2) when the oil-pumping machine is at the bottom dead center of the stroke. The design of “sharing the spiral grooves” in accordance with the invention leads to a sharp decrease in the width of the secondary sheave, thereby significantly reducing the rotational inertia and the volume and use of materials of the oil-pumping machine as well. The use of a plurality of oil pumping rod suspension ropes and balance weight traction ropes greatly increases the operational stability. The looseness of one of the ropes or occurrence of other abnormalities will not affect the normal operation of the oil-pumping machine.

As shown in FIG. 8, the angle α between four first and second holes 5a, 5b along circumference of the secondary sheave is 110°-145°, preferably, 120°, and at least, equal to or more than 60°. The balance weight traction rope 10 and the oil pumping rod suspension rope 2 are configured such that they do not interfere with each other and have opposite torques with respect the secondary sheave 5 during the operation. It could be conceivable by those skilled in the art that the first or second holes can be even numbers except 4, such as 2, 6 and 8, which is also within the scope of the invention. The configuration has greatly improved the operational stability of the oil pumping rod and the balance weight. A slack in one of the ropes will not affect the operation of the balance weight and the oil pumping rod.

According to a more preferred embodiments of the disclosure, a plurality of oil pumping rod suspension rope and balance weight traction rope are formed by one main rope, respectively. For instance, in the embodiment as shown in FIGS. 5-7 in which n=2, four balance weight traction rope formed by one single main rope are configured such that one end of the main rope is fastened in first one out of the four first holes 5a close to one end of the secondary sheave 5 (e.g., the leftmost first hole) via an adjustable fastener, and the other end of the main rope extends out of the first one, then inserts into the secondary sheave 5 through an second one of the first holes which is adjacent to the first one, then extends out of a third one of the first holes adjacent to the second one (a fixing and adjusting unit 24 in form of a fixed pulley protruding inwardly is arranged within the secondary sheave 5 to prevent the wire-type rope from buckling and to adjust the tension of the ropes) and then inserts into a fourth one of the first holes (the rightmost first hole) adjacent to the third one and is fastened there via an adjustable fastener, forming four balance weight traction ropes 10 of equal length. Four oil pumping rod suspension rope formed by one main rope define continuous lower ends (free ends), where two movable pulley (See FIG. 3) are disposed so as to better balance the suspension of the oil pumping rod. Similarly, four suspension ropes formed by one single main rope can also be similarly configured. Moreover, a fixing and adjusting unit in form of a fixed pulley can be provided in the similar manner in the arrangement of the main rope forming the balance weight traction rope. In addition, regardless of the number of the first and second holes, the arrangement mentioned above can also be used.

In reference to another embodiment of the invention as schematically shown in FIGS. 9a to 9c, the sharing configuration of the spiral grooves by the balance weight traction rope and the oil pumping rod suspension rope is illustrated, showing the concept of the invention. In the embodiment, the inclination angle of the spiral grooves is exaggeratedly shown and in the illustrated example, it only shows n=1 and m=8, wherein the second holes 5b are closer to the center than the first holes 5a. As shown in FIGS. 9a and 9b, the secondary sheave is bisected into a left half and right half by a horizontal center line TT′ perpendicular to the longitudinal axis of the secondary sheave (the portion of the secondary sheave having an embedded annular gear has not been taken into consideration), wherein the first and second holes as well as spiral grooves are symmetrical with respect to the horizontal center line and the spiral grooves form a “\/” shape on the secondary sheave from a top view. FIG. 9c is a schematically right side view of the secondary sheave, with the illustrated clockwise arrow R1 indicating a direction in which the oil pumping rod suspension rope 2 unwinds from the secondary sheave 5 while the balance weight traction rope 10 winds around the secondary sheave and with the illustrated counterclockwise arrow R2 indicating another direction in which the oil pumping rod suspension rope 2 winds around the secondary sheave 5 while the balance weight traction rope 10 unwinds from the secondary sheave. Consequently, when the secondary sheave 5 rotates in clockwise direction R1 to drive the oil pumping rod from the top dead center of the stroke towards the bottom dead center, the oil pumping rod suspension rope 2 and the balance weight traction rope 10 move from the arrangement shown in FIG. 9a to that in FIG. 9b (wherein ropes are marked as thick solid lines while the spiral grooves which are not occupied by the ropes as dashed lines). It is apparent that as the oil pumping rod suspension rope 2 continuously leaves the spiral grooves in response to the rotation of the secondary sheave, the balance weight traction rope 10 continuously winds around the shared spiral grooves. Since the four first and second holes 5a, 5b are arranged in the included angle along the circumference of the secondary sheave as mentioned above, the winding extent of the balance weight traction rope 10 will always lag behind the unwinding extent of the oil pumping rod suspension rope 2 in a distance. For example, there exist some spiral grooves which are not occupied by the ropes and shown in dashed lines. When the secondary sheave 5 rotates in the anticlockwise direction R2 to drive the oil pumping rod from the bottom dead center of the stroke towards the top dead center, the oil pumping rod suspension rope 2 and the balance weight traction rope 10 operate reversely.

With a certain number of holes, the quantity of the spiral grooves is determined by the circles of the balance weight traction rope and the oil pumping rod suspension rope to be winding around, which in turn depend on the diameter and stroke of the secondary sheave. It is conceivable by those skilled in the art that the winding length of the balance weight traction rope and the oil pumping rod suspension rope on the secondary sheave is longer than the stroke of the oil-pumping machine, in a bid to ensure the normal operation of the oil-pumping machine.

During the operation of the oil-pumping machine, the electric motor rotates forward to drive the cylinder-type secondary sheave 5 clockwise, wherein four oil pumping rod suspension ropes 2 will wind around the secondary sheave, thus pulling the oil pumping rod 1 to move upward, and the balance weight traction ropes 10 which wound around the spiral grooves in the secondary sheave 5 move downward due to the gravity of the balance weight 11. When the electric motor rotates in an opposite direction, the cylinder-type secondary sheave 5 moves anticlockwise, wherein the balance weight traction ropes 10 will wind around the secondary sheave 5, thus pull the balance weight 11 to move upward, and the oil pumping rod suspension ropes 2 which wound peripherally around the secondary sheave 5 move downward because of a combination of the gravity of the oil pumping rod 1 and reverse rotation of the electric motor 27.

The forward and reverse rotation of the electric motor 27 is only to change the upward and downward reciprocating motion of the oil pumping rod 1 and balance weight 11 under the gravitational field and overcome the friction between the cylinder-type secondary sheave 5 and the traction rope and the suspension rope. The balance and symmetry during the upward and downward movement rely on the potential energy in a gravitational field produced by free fall of the system. The change of movement direction depends on the positive and negative electromotive force of the electric motor 27 together with the gravitation and the symmetry of the mechanical counterweight. The switch between potential energy and kinetic energy can be made best use in mechanical transmission. The digital control technologies of the electric motor allow the numerical control technique to make an accurate control on times and accuracy of the stroke of the oil-pumping machine, and also realize follow-up control on the required load between balance torque and maximum torque. The balance torque occurs at ordinary working conditions while the maximum torque occurs at uninstallation and installation conditions during workover or is required to output by the follow-up control of the electric motor to overcome sandy block under the well. This torque is 2.5 times greater than the torque required when the balance weight 11 is lifted to a loading position, where the gravity of the balance weight 11 is not included.

The cylinder-shaped secondary sheave in its interior comprises an adjustable fastener and a transition fixed pulley (see FIG. 6) for the suspension rope and the traction rope respectively. A fixing and guiding rope 11′ in form of a wire (see FIG. 2) is provided through the center of the balance weight 11. Two pairs of horizontal pulleys parallel to each other suspend on the surface of the rope, aiming to coordinate with the upward and downward travel of the balance weight 11. If the balance weight 11 travels over the stroke, it will be controlled and stopped by a limit switch for upward and downward stroke, and an alarm is activated.

During the operation of the oil-pumping machine, the operation and traction system for balance weight (see FIG. 1) and the operation and traction system for oil pumping rod (see FIG. 2) are in dynamic balance. In order to enable the first and second transmission of the multi-stage speed reducer 106 and the annular gear of the cylinder-type secondary sheave 5 to keep stable during running and reversing, the cylinder-type secondary sheave 5 at two ends of its cylinder interior comprises two of flat spiral spring arrangements 13, respectively (see FIG. 4). When the stroke of the oil-pumping machine is at the highest or lowest point, only one of the flat spiral spring arrangements 13 is in an energy storage mode, wherein the extensible length of the springs is longer than the stroke of the oil pumping rod. The two flat spiral spring arrangements are mounted inside the cylinder-type secondary sheave in opposite directions. As shown in FIG. 11a, during the forward rotation of the electric motor, one of the two spring arrangements store energy while the other arrangement releases energy, producing active and reactive torque and greatly reducing a reversing impact. The flat spiral springs facilitate a smooth reversal of the electric motor 27 and provide both mechanically and electrically flexible follow-up control. This significantly reduces the electrical loss and damage to machines (coupler) caused by frequent reversal of the electric motor 27, is more energy saving, and improves the durability of the electric motor 27 and the electric control and mechanical components. In one example of the installation of the flat spiral springs, either of the two sides of the secondary sheave (head sheave) may be provided with a spring and then the secondary sheave rotates to allow the spring in a maximum energy storage mode, wherein an overall length defined by revolution number and circumference of the head sheave is longer than the stroke length. At the same time, a fastening pin is used to fasten the other end of the flat spiral spring in the head sheave. When the fastening pin is mounted, the head sheave is inhibited from rotating. Then, another flat spiral spring is mounted at the other end of the sheave in a release mode. After that, the head sheave is released.

It is advantageous in the disclosure that the guide sheave 4 is mounted on the guide sheave support 20 via a guide sheave bearing 21 and thus mounted on the platform 8 pivotally in a plane perpendicular to a plane of the platform 8. In addition, the secondary sheave 5 rotates to drive the guide sheave 4 to pivot upwardly relative to the platform 8. Specifically, a suspension loop is provided on the guide sheave support 20 and the cylinder body of the secondary sheave 5. During the workover, when the oil pumping rod and the suspension rope are disconnected and the guide sheave is pulled upwardly and backwards, the suspension loop is hung on the guide sheave support and the secondary sheave, respectively, thereby releasably linking thereto. This arrangement allows the electric motor 27 to drive the secondary sheave 5 to rotate, such that the suspension loop pulls the guide sheave support 20 and thus the guide sheave 5 to move upwardly. Consequently, it easily makes room for workover without any manual dismantlement of the guide sheave or displacement of the entire machine, which saves the cost and time for workover to a great extent. When the guide sheave 5 pivots upwardly, the electric motor is preferably controlled by inching, in order to drive the secondary sheave. Furthermore, the platform is provided with a baffle (not shown) which is used to limit the angle of upward pivot of the guide sheave.

According to a preferred embodiment of the invention, as shown in FIG. 2, the platform 8 at its end adjacent to the oil pumping rod comprises domed bolts 22 for adjusting and positioning guide sheave, which are mounted on both sides of the platform 8 and cooperate with the notch or groove at two sides of the guide sheave support 20 to fix the guide sheave 4 in position and prevent the guide sheave support 20 from deviating, thereby enhancing the structural stability. The height of the domed bolt is adjustable by threading the domed bolt, such that the elevation angle between the guide sheave 4 and the platform 8 can be adjusted. An elevation angle of the guide sheave 4 is set with respect to the platform 8, in order to make the guide sheave to easily pivot upward. In the invention, the elevation angle is in range of 6° to 12°, preferably 8°-10°, and more preferably at 90. Adjustment of the elevation angle can regulate the relative position of the guide sheave and the wellhead.

As mentioned above, the electric motor 27 according to the invention couples to and drives the secondary sheave 5 via the speed reducer 106. According to a preferred embodiment of the invention, the cylinder body of the secondary sheave at one end comprises an annular gear 7 which meshes with the output shaft 18 of the multi-stage speed reducer 106 having the first transmission ratio, thus defining the second transmission ratio between the annular gear and the gear shaft. This design improves the mechanical structure and work environment, provides a compact structure of the transmission and saves the cost of manufacture compared with the traditional internal mesh transmission. Further, the meshed teeth of the internal mesh transmission are increased, thus improving the transfer of mechanical torque, reducing the wear between the teeth, and prolonging the service lifetime of the gear shaft and annular gear.

As shown in FIG. 7, the input end of the multi-stage speed reducer 106 couples to the output shaft of the electric motor 27 through a coupler 28 and the multi-stage speed reducer 106 is provided with a power-off brake disc 26 (namely, a brake) at the end (outside) distal to the coupler 28, which constitutes a mechanical driving system and electrical transmission system. The multi-stage speed reducer 106 is fixed on the vertical sleeve type platform while the electric motor 27 is positioned on the electric motor support on top of the platform and horizontally engages with the coupler for the multi-stage speed reducer.

However, it is conceivable by those skilled in the art that under a light load, 15 the electric motor may directly couple to the secondary sheave. Alternatively, in other preferred embodiments as shown in FIG. 13-16, the secondary sheave is provided with the annular gear 7, with a difference that the electric motor couples to the annular gear 7 of the secondary sheave 5 by means of a transmission 6.

The embodiments as shown in FIG. 13-15c are generally similar to that shown in FIG. 1, but with one main difference that the transmission 6 in form of a planetary gearing is provided. As shown in FIG. 13, the oil-pumping machine of the disclosure is in form of a cylinder-type oil-pumping machine, wherein the secondary sheave 5 rotates around a secondary sheave shaft 19 extending along the longitudinal axis of the secondary sheave. The transmission 6 comprises a sun gear 6a, four planet gears 6b evenly spaced around the circumference of the sun gear 6a and a planet carrier 6c fixed to the secondary sheave shaft 19, wherein the output end of the electric motor 27 couples to and drives the sun gear 6a to rotate, the sun gear 6a meshes with and thus drives each planet gear 6b to rotate, and the planet gears 6b mesh with the annular gear 7 to drive the secondary sheave 5 to rotate, as shown in FIG. 15a-15c. It could be understood by those skilled in the art that although there are four planet gears 6b in the embodiment, the arrangement having two, three or more than four planet gears is also within the scope of the invention, as desired.

It is Advantageous that the electric motor is in form of a permanent magnetic synchronous tractor 27, of which the output end couples to and thus drives the secondary sheave 5 via the transmission 6. It is known by those skilled in the art that the permanent magnetic synchronous tractor itself has an electromagnetic brake 6e, such that there is no need to provide an additional electromagnetic brake mechanism. The permanent magnetic synchronous tractor in the invention can be available from, for example, the WYJ2-3.001800 gearless three-phase AC tractor produced by Boma Motor Co., Ltd in Xuchang, C N. It can be understood by those skilled in the art that other types of permanent magnetic synchronous tractors could also be used as desired.

The permanent magnetic synchronous tractor is directly connected with the secondary sheave only through the transmission which includes the sun gear, planet gear and planet carrier without a traditional gearbox and relevant drive shaft, thus simplifying the transmission, allowing the driving with gears but without a drive shaft and leading to a more compact transmission system for the oil-pumping machine. As the annular gear is loaded evenly, it significantly improves driving efficiency and has a low wear. As compared to the existing speed reducer with a cylindrical gear, the permanent magnetic synchronous tractor significantly increases the transmission efficiency and minimizes the energy loss. The permanent magnetic synchronous tractor is fixed to the electric motor support on the platform with its output end engaging with the annular gear of the secondary sheave 5 through the planet gears 6b. This transmission system is particularly suitable for the oil-pumping machines that have a long stroke but few stroke times.

Similar to FIG. 4, FIG. 18 shows the flat spiral spring arrangements 13 arranged inside the secondary sheave 5. In FIG. 18, the connection of transmission in form the planetary gearing with the secondary sheave 5 is further shown.

FIG. 16 shows another embodiment that is similar to that shown in FIG. 13-15c, with one difference that, in order to further enhance the strength of the vertical sleeve type main frame, a reinforcement structure is arranged on one side of the vertical sleeve type main frame 9 opposite to the oil pumping rod 1 to form a cavity for the control cabinet. The control cabinet 12 for controlling the electric motor is arranged in the cavity, under an indoor working condition. This improves the outdoor working conditions of the current control cabinet and enhances anti-theft security and safety. Similarly, the control panel 114 of the control cabinet is positioned externally onto the gate at the operator's eye level, thereby facilitating the operation and control without entering into the cavity.

In addition, considering the fact that a single offshore wind generator has a maximum power up to 5000 KW and the onshore wind generator has an output power ranging from 2000 KW to 3000 KW, the wind generator has an improved performance and is sold at a declining price, with mature wind power generation technologies. For the oil-pumping machine as shown in FIGS. 1 to 3, the transmission power, generally speaking, stands at around 10 KW during normal operation. As for a depth of 1,000 m-1,200 m in a well, the balance weight is lifted and put down at an instantaneous power ranging from 20 KW to 25 KW, which largely depends on the torque or speed of the electric motor. Therefore, the ordinary wind generators and luminous energy generators can meet the oil-pumping machine's demand for electricity supply. In the case of deep well, higher power and reserve power for light and wind energy can be used.

Accordingly, in the embodiment as shown in FIG. 16, the oil-pumping machine is provided with a wind power system, comprising a wind generator 123, a fan controller 125 and a storage battery 116 which are connected to each other in sequence. The storage battery 116 is by means of an inverter 126 connected to a control and management system of the oil-pumping machine that is used to control the electric motor 27, as shown in FIG. 17. The wind generator 123 is mounted on the platform 8 on top of the main frame. The diameter of a wind turbine 124 on the wind generator 123 not only depends on the desired output power, but also it should be considered that the running of the wind turbine 124 should not interfere in the normal operation of the oil-pumping machine. A stop mechanism 118 for horizontal rotation of the fan is also provided to limit the rotation range of the wind generator 123 and further prevent the vane of the wind turbine 124 from interfering in the operation of the oil-pumping machine. It is advantageous that the storage battery 116 is positioned within the balance weight 11 and connected to the electric motor via a guide cable 115, thereby saving space and balancing the weight as well.

In addition to the wind power system, the oil-pumping machine is also provided with a luminous energy power system, comprising a photovoltaic module 117 connected to the storage battery 116. A photovoltaic controller 29 is arranged between the photovoltaic module 117 and the storage battery 116.

As the power curve of the wind generator is in relation to the wind force in the wind field, measures are taken to reasonably allocate wind-turbine power. That is the surplus power in strong wind is used for charging, and under a natural condition where the wind energy in the wind field is stronger than the luminous energy, the energy from the luminous energy power system can only be used for charging. The storage battery 116 plays a role of peak modulation. In the invention, the meteorological data of a specific region is input into the control and management system 31 of the oil-pumping machine for management and allocation of power energy as desired. The invention also provides a control system for the oil-pumping machine. The control system mainly comprises an oil-pumping driving device, which is used to drive the oil pumping rod to move upwards and downwards, and a control device for controlling the driving device. The control system may be in form of, for example, the above-mentioned control and management system of the oil-pumping machine or other suitable control systems.

In connection with FIGS. 10a-12, a method of controlling the oil-pumping machine and its effects are described as follow. The overall numerical control for the control system of the oil-pumping machine aims to realize precisely real-time control, targeting in the actual conditions during the operation of the oil-pumping machine, namely stroke times, stroke length and reversing, and obtain optimal efficiency.

FIG. 12 shows a control curve regarding the speed V1 and V2 in the upward and downward stroke D of the oil-pumping machine, wherein C1 and C3 refer to acceleration phase, E1 and E2 to uniform velocity phase, C2 and C4 to speed reduction phase, Z to integral time (see FIG. 11b), D to stroke and T/m to one time of stroke. Firstly, the final stroke value is set to 9 (stroke value may be as precise as decimal places) and then the speeds for upward V1 and downward V2 strokes are set. The downward stroke speed V2 is lower than the upward stroke speed V1, so as to prolong the pumping time for liquid filled in the oil-pumping machine and improve liquid production capacity. The traditional oil-pumping machine is unable to achieve the operation at different upward and downward stroke speeds. The adjustability of the upward and downward stroke speeds V1, V2 is, in fact, done by setting different output frequencies for the forward and backward rotation of the electric motor with an S-shape control. Concerning the control of the stroke times by the control system, the forward and backward rotation of the electric motor 27 represents an operation cycle (T/m) for the upward and downward strokes of the oil pumping rod, with the number of operation cycles per minute being the stroke times. This can be realized by controlling the reversing times of the forward and backward rotation of the electric motor 27 per minute, wherein the forward and backward rotation has different speeds. It mainly focuses on the control of different speeds of the forward and backward rotation, which defines the stroke times and upward and downward stroke speeds of the oil pumping rod.

In addition, the control system provides a flexibly reversing control. At the point of reversing transition between the forward and backward rotation of the electric motor 27, the controller controls the electric motor 27 with an integral time Z of 0.1 s, so as to provide electrical damping for the reversing of the electric motor, and allow a flexibly meshing engagement between a plurality of set of gears in the multi-stage speed reducer 106 (first transmission ratio) and the annular gear (second transmission ratio) within the secondary sheave at the time of forward and backward. This is to prevent from the collision caused by excessive impulse due to reversing transition between forward and backward subjecting to a hard connection in a long term. The control provides a flexible control on the reversing of the electric motor 27. In addition, it has further improved effects in that the mechanically flat spiral springs may provide both active and counteractive forces and energy storage property as well as smooth damping characteristic.

FIG. 10
a shows a curve regarding the relationship between the pressure P and the time T during reversing transition of the forward and backward movement in the output shaft of the electric motor when the induction motor is out of control, which shows changes in the rotational inertia in the reversing area M₁of the electric motor. FIG. 10b shows a curve regarding the relationship between the pressure and the time during reversing transition of the forward and backward movement in the secondary sheave when it is out of control, which shows changes in the rotational inertia in the reversing area M₂of the secondary sheave. FIG. 10c shows a curve regarding the relationship between the pressure and the time during reversing transition of forward and backward movement in the meshing engagement between the output gear shaft of the transmission and the internal teeth in the cylinder of the secondary sheave when the electric motor and secondary sheave are out of control, which shows sum of the rotational inertia and impulse in the reversing area M₃. FIG. 11a is a curve regarding the physical properties of a pair of flat spiral springs within the secondary sheave, which shows simultaneous forward and backward forces occur. As illustrated, when one flat spiral spring is in the energy storage mode Q₁, the other one is in the energy release mode Q_O, referred to as mechanical damping. FIG. 11b shows the relation between the rotational speed and the time during the reversing transition of forward and backward movement in the output shaft when the induction motor or permanent magnet synchronous motor is under control, which shows the integral time Z during the reversing transition, also regarded as electrical damping. An electrical damping control for the oil-pumping machine can be achieved by the control system according to the invention, resulting in a condition curve P₁regarding the cylinder-type oil-pumping machine as shown in FIG. 11c, which shows a significant increase in performance during reversing transition as compared to the condition curve P₂of the beam-pumping unit. For example, an overshoot area S is avoided as shown in the shadow in FIG. 11c.

To sum it up, the oil-pumping machine of the invention has some favorable effects as follows:

1. High power saving rate: The oil-pumping machine of the invention significantly improves the transmission efficiency as compared to the traditional beam-pumping unit shifts by means of changing from a circular motion of the traditional unit to a linear motion, and electricity is cut down by 50%-70%, which is achieved by using a secondary sheave with smaller axial dimension, improved transmission and clean energies.

2. The concept of sharing spiral grooves sharply cuts down the axial dimension of the secondary sheave, thereby reducing energy consumption, offering excellent torque balance and adapting to the current narrow balance weight.

3. Precise adjustment of the balance weight is time- and effort-saving. The oil-pumping machine substantively eliminates the loss caused by renewable generation through electric motor's electromotive force, and an electricity feedback device can be installed to give a feedback generated by the friction force during the reversing to the power grids.

4. It facilitates adjustment of the balance weight, stroke times and stroke. The optimized management on the oil production allows automatically intermittent oil extraction, which is required for optimization of oil extraction. The interval for the intermittent oil extraction can be set as desired which may be automatically performed by the control management system. This can substantially reduce the waste of power and pump wear, prolong the lifetime for the pump and save the electricity.

5. The upward and downward stroke speeds for the oil pumping rod can be adjusted as desired. The faster upward stroke speed and slower downward stroke speed are configured such that a fast fluid output and prolonged oil pumping for the oil filling within the cavity of the oil-pumping machine may be achieved by the faster upward speed and lower downward speed respectively, thereby increasing the pumping efficiency.

6. In the system in the invention, a short message unit of industry grade GSM Chinese (English) may be utilized for detecting watchdog time, instant report, patrol report, check report and watchdog of pause contents, stroke, stroke times, temperature rise, current, voltage, and ammeter value, indicator diagram, P value and S value.

7. The control system of the invention further provides a plurality of connection means for the electric motor and the secondary sheave.

8. The combination of the winding configuration of the secondary sheave and other components of the oil-pumping machine provide an optimally control on the dynamic balance during the operation of the oil-pumping machine.

Although various embodiments of the disclosure have been described in detail, it should be understood that those description is only construed rather than limiting. Those skilled in the art can make various modifications on the illustrative embodiments without departing from the spirit or scope of the invention.

Number	Date	Country	Kind
201110024440.7	Jan 2011	CN	national
201120292680.0	Aug 2011	CN	national

OIL-PUMPING MACHINE

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CPC

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