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TECHNICAL FIELD 
       [0001]    The present invention relates to the technical field of oil production equipment for an oil field, more particularly to a flywheel energy storage oil pumping machine. 
       BACKGROUND 
       [0002]    The working principle of an oil pumping machine with a sucker rod is pumping petroleum out from an oil well through the vertical up-and-down movement of the sucker rod. An oil pumping machine with a sucker rod in the prior art generally comprises a speed reducer, a balance system, a reversing device and various mechanical driving devices. The energy transfer way of such an oil pumping machine with a sucker rod is: electric motor-belt wheel-speed reducer-balance system-reversing device-various mechanical driving devices. There are many transfer links, resulting in high energy consumption and serious waste. During the operating of such oil pumping machines, the work done by the oil pumping machines is not uniform due to their structural features. In the up-and-down stroke of such an oil pumping machine, the energy required by the sucker rod varies greatly, while the output power of the electric motor must correspond to the power required by the movement of the sucker rod. Specifically, the power of the electric motor must meet maximum power in the up-and-down stroke. Therefore, the installed capacity of the electric motor is large, generally multiple times larger than actually required average power, and even above 7 times. Meanwhile, due to the starting characteristics of the electric motor, there is a large impact to the power grid, thereby causing serious pollution to the power grid. A Chinese Utility Model CN200982182Y, published on Nov. 28, 2007, disclosed such an oil pumping machine. 
       SUMMARY OF THE INVENTION 
       [0003]    In view of the deficiencies in the prior art, the object of the present invention is to provide a flywheel energy storage oil pumping machine, which is simple in structure, cheap, small in volume, light in weight, small in the installed capacity of the electric motor, low in energy consumption, high in efficiency, low in failure rate, and free from pollution to the power grid. 
         [0004]    To solve the above technical problem, the present invention employs the following technical solution: a flywheel energy storage oil pumping machine is provided, comprising an electric motor and a control device, and further comprising a rotary spindle; 
         [0005]    a lifting roller, used for raising and lowering a sucker rod, sleeved on the rotary spindle, the separation or joining of the rotary spindle from/with the lifting roller being realized via clutches; 
         [0006]    a roller drive wheel, fixedly connected with the lifting roller to form a whole; 
         [0007]    an energy adjustment flywheel; 
         [0008]    a transmission, a low-speed end of which is connected to the rotary spindle while a high-speed end of which is connected to the energy adjustment flywheel; 
         [0009]    an energy feedback device, used for transferring, to the energy adjustment flywheel via the transmission, energy generated during lowering the sucker rod, to realize the accelerated rotation of the energy adjustment flywheel for energy storage, the energy of the energy adjustment flywheel being able to be transferred to the lifting roller for raising the sucker rod when the lifting roller raises the sucker rod; 
         [0010]    In the flywheel energy storage oil pumping machine provided by the present invention, the rotary spindle is driven by the electric motor, and through transmission, the energy adjustment flywheel begins to rotate. When the flywheel reaches to a certain rotate speed, the sucker rod begins to be lifted, and the pumping machine begins to work. When the pumping machine is working, the potential energy of the sucker rod during its down stroke is transferred to the energy adjustment flywheel via the energy feedback device, and then converted by the energy adjustment flywheel into the accelerated rotation of the energy adjustment flywheel, so that the energy is stored. Meanwhile, the energy feedback device may control the speed of the sucker rod during the down stroke, thereby making the down stroke of the sucker rod very stable and decreasing the impact. During the up stroke of the sucker rod, the sucker rod is driven to rise through the rotational energy of the energy adjustment flywheel, thus to release energy. In this way, the output power of the electric motor does not have to correspond to the instant power consumption of the sucker rod during rising of the sucker rod. Therefore, the power of the electric motor can almost get close to a theoretical minimum value, thereby greatly reducing the installed capacity of the electric motor, making the power output more stable, decreasing the impact to the power grid, and greatly reducing the pollution to the power grid. In addition, the oil pumping machine provided by the present invention is not provided with a balance system, a four-bar linkage and other essential members of an existing oil pumping machine, so its structure is simple, both its size and weight are reduced greatly, and its reliability is enhanced greatly. 
         [0011]    As a preferred technical solution of the present invention, the energy feedback device comprises a drive shaft and a first drive wheel and a second drive wheel disposed on the drive shaft, the first drive wheel or the second drive wheel being connected to the drive shaft via an energy feedback clutch, the first drive wheel and the roller drive wheel being a pair of meshed gears, and the second drive wheel being connected to the transmission. 
         [0012]    As a preferred technical solution of the present invention, the energy feedback device comprises a rotating shaft, a first drive wheel and a second drive wheel, the rotating shaft being connected to the second drive wheel via an energy feedback clutch, the first drive wheel, the second drive wheel and the roller drive wheels being gears, the first drive wheel being positioned between the roller drive wheel and the second drive wheel and being meshed with both the roller drive wheel and the second drive wheel, and the second drive wheel being connected to the transmission. 
         [0013]    As a preferred technical solution of the present invention, the energy feedback device comprises a drive shaft and a first drive wheel, the drive shaft being connected to the first drive wheel via an energy feedback clutch, and the first drive wheel being connected to the roller drive wheel via a driving belt. 
         [0014]    As a preferred technical solution of the present invention, the energy feedback device comprises a drive shaft, a transition wheel fixedly connected to the rotary spindle, and a first drive wheel and a second drive wheel disposed on the drive shaft, the first drive wheel or the second drive wheel being connected to the drive shaft via an energy feedback clutch, the first drive wheel and the roller drive wheel being a pair of meshed gears, and the second drive wheel being connected to the transition wheel via a driving belt. 
         [0015]    As a preferred technical solution of the present invention, the energy feedback device comprises a drive shaft, a transition wheel fixedly connected to the rotary spindle, and a first drive wheel and a second drive wheel disposed on the drive shaft, the first drive wheel or the second drive wheel being connected to the drive shaft via an energy feedback clutch, the second drive wheel and the transition wheel being a pair of meshed gears, and the first drive wheel being connected to the roller drive wheel via a driving belt. 
         [0016]    As a preferred technical solution of the present invention, the energy feedback device comprises a drive shaft, a transition wheel fixedly connected to the rotary spindle, and a first drive wheel and a second drive wheel disposed on the drive shaft, the first drive wheel or the second drive wheel being connected to the drive shaft via an energy feedback clutch, the first drive wheel, the second drive wheel and the roller drive wheel being gears, the first drive wheel being meshed with the roller drive wheel, the transition wheel being provided with internal teeth, and the second drive wheel being meshed with the internal teeth. 
         [0017]    As a preferred technical solution of the present invention, an electric motor gear, meshed with the internal teeth, is mounted on the output shaft of the electric motor; or, the output shaft of the electric motor is connected to the transmission via an electric motor clutch. 
         [0018]    As a preferred technical solution of the present invention, the energy feedback clutch is an overrun clutch. 
         [0019]    The energy feedback clutch may be a mechanical clutch, for example, the whole clutch is divided into a fixed portion and a slide portion that can be engaged with each other. The slide portion may be pushed by an oil cylinder or air cylinder, so that the slide portion is joined with the fixed portion. If the energy feedback clutch is an overrun clutch, the structure of the whole energy feedback device is simpler, and standard components may be purchased directly. 
         [0020]    As a preferred technical solution of the present invention, the energy generated during lowering the sucker rod is transferred to the energy adjustment flywheel via the transmission to realize the accelerated rotation of the energy adjustment flywheel; or, the energy generated during lowering the sucker rod passes through the rotary spindle first and is then transferred to the energy adjustment flywheel via the transmission to realize the accelerated rotation of the energy adjustment flywheel. 
         [0021]    As an important component of the flywheel energy storage oil pumping machine provided by the present invention, the energy feedback device can transfer the energy generated during lowering the sucker rod to the energy adjustment flywheel, and then the energy is converted into the accelerated rotation of the energy adjustment flywheel to realize energy storage. Therefore, transfer links should be reduced to as few as possible, in order to improve the efficiency and lower the failure rate. The two transfer ways mentioned above have few intermediate links and high efficiency. 
         [0022]    The present invention has the following advantages: 
         [0023]    1. The oil pumping machine has a simple structure, high efficiency, small installed capacity of the electric motor, no pollution to the power grid, low failure rate and high reliability; 
         [0024]    2. The overall structure of the oil pumping machine is simplified greatly, so a large amount of steel is saved, the cost is reduced, and the competitiveness is enhanced; the oil pumping machine is small in size, so it is convenient for transportation and installation; and in addition, the whole oil pumping machine may be protected with a housing, so the protection grade of the oil pumping machine is improved; 
         [0025]    3. With strong adaptability, the oil pumping machine may be applied to regular oil wells or heavy oil recovery; and it may be applied to oil recovery at both land and sea. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]    The present invention will be further described as below with reference to accompanying drawings: 
           [0027]      FIG. 1  is a structure diagram of Embodiment 1 of the present invention; 
           [0028]      FIG. 2  is a structure diagram of Embodiment 2 of the present invention; 
           [0029]      FIG. 3  is a structure diagram of Embodiment 3 of the present invention; 
           [0030]      FIG. 4  is a structure diagram of Embodiment 4 of the present invention; 
           [0031]      FIG. 5  is a structure diagram of Embodiment 5 of the present invention; 
           [0032]      FIG. 6  is a structure diagram of Embodiment 6 of the present invention; and 
           [0033]      FIG. 7  is a structure diagram of Embodiment 7 of the present invention; 
       
    
    
       [0034]    In the figures:
     1 —electric motor;  2 —rotary spindle;  3 —control device;  4 —lifting roller;  5 —clutch;  6 —roller drive wheel;  7 —energy adjustment flywheel;  8 —transmission;  9 —energy feedback device;  901 —drive shaft;  902 —transition wheel;  902   a —internal teeth;  903 —first drive wheel;  904 —second drive wheel;  905 —energy feedback clutch;  906 —driving belt;  10 —electric motor gear;  11 —electric motor clutch.   
 
       DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0036]    The following description illustrates only the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. 
       Embodiment 1 
       [0037]    Referring to  FIG. 1 , a flywheel energy storage oil pumping machine comprises an electric motor  1  and a control device  3 , and further comprises a rotary spindle  2 , a lifting roller  4 , a roller drive wheel  6 , an energy adjustment flywheel  7 , a transmission  8 , and an energy feedback device  9 . The control device  3  comprises a PLC (Programmable Logic Controller), a position switch, a connection cable, etc., and is used for controlling the action of the whole oil pumping machine. The electric motor  1  may be a general electric motor or a variable-frequency electric motor. The rotary spindle  2  is an integral spindle. Of course, the rotary spindle  2  may be one formed by integrating a plurality of split spindles via couplers or by welding or other manners. 
         [0038]    The electric motor  1  drives the rotary spindle  2  to rotate. The lifting roller  4  is connected to a sucker rod (not shown) via a soft connector. The sucker rod is driven to rise by the forward rotation of the lifting roller  4 , while during lowering, the sucker rod drives the lifting roller  4  to rotate reversely, so that up stroke and down stroke of the whole oil pumping machine are completed, and the oil pumping work is thus completed. The lifting roller  4  is sleeved on the rotary spindle  2 , so that the relative rotation can be generated between the lifting roller  4  and the rotary spindle  2 . The rotary spindle  2  is separated from or joined with the lifting roller  4  via clutches  5 . The clutches  5  may be electromagnetic clutches, friction clutches, hydraulic clutches or other known clutches. In this embodiment, the clutches  5  are mechanical clutches, and there are total two clutches  5  disposed at two ends of the lifting roller  4 . Of course, there may be only one clutch  5 . Each clutch  5  includes two portions, one of which is a fixed portion directly fixed on the lifting roller  4 , while the other one is a slide portion connected to the rotary spindle  2  in a form of spline. The two portions are provided with a neck and a latch which are engaged with each other. Pushed by an air cylinder, an oil cylinder or other devices, the slide portion may slide left and right in the axial direction, thereby realizing the join (separation) of the lifting roller  4  with (from) the rotary spindle  2 . The roller drive wheel  6  is fixedly connected to the lifting roller  4  by welding, screwing or other known fixing manners. The transmission  8  may be in many forms. The transmission  8  may be a two-stage, three-stage, four-stage or five-stage transmission, or a continuously variable transmission, or a comprehensive transmission. However, no matter in which form, the transmission  8  has a low-speed end and a high-speed end. The low-speed end of the transmission  8  is connected to the rotary spindle  2 , so that the rotation speed of the rotary spindle  2  is relatively low, usually dozens of revolutions per minute; and the high-speed end of the transmission  8  is connected to the energy adjustment flywheel  7 . After the energy adjustment flywheel  7  is connected to the high-speed end, its rotation speed is very high and may reach hundreds and even thousands of revolutions per minute. The energy adjustment flywheel  7  may be directly fixed on the shaft at the high-speed end of the transmission  8 , or, disposed on the shaft specially and then connected to the shaft at the high-speed end of the transmission  8 . 
         [0039]    The energy feedback device  9  is used for transferring, to the energy adjustment flywheel  7 , energy generated during lowering the sucker rod, to realize the accelerated rotation of the energy adjustment flywheel  7 . Then, the energy of the energy adjustment flywheel  7  is transferred to the lifting roller  4  for raising the sucker rod when the lifting roller  4  raises the sucker rod. The energy feedback device  9  at least comprises a drive shaft  901  and an energy feedback clutch  905 . The energy feedback clutch  905  is generally an overrun clutch. There are many ways for the energy generated during lowering the sucker rod to pass through the energy feedback device  9 , wherein, preferably, the energy generated during lowering the sucker rod passes through the energy feedback device  9  first and is then transferred to the energy adjustment flywheel  7  via the transmission  8 , to realize the accelerated rotation of the energy adjustment flywheel  7 ; or, the energy generated during lowering the sucker rod passes through the energy feedback device  9  first, then passes through the rotary spindle  2 , and is finally transferred to the energy adjustment flywheel  7  via the transmission  8 , to realize the accelerated rotation of the energy adjustment flywheel  7 . In this embodiment, the energy generated during lowering the sucker rod passes through the energy feedback device  9  first and is then transferred to the energy adjustment flywheel  7  via the transmission  8 , to realize the accelerated rotation of the energy adjustment flywheel  7 . During the up and down stroke of the sucker rod, the rotation direction of the rotary spindle  2  and the rotation direction of the energy adjustment flywheel keep unchanged. 
         [0040]    In this embodiment, the energy feedback device  9  comprises a drive shaft  901  and a first drive wheel  903  and a second drive wheel  904  disposed on the drive shaft  901 . The first drive wheel  903  is connected to the drive shaft  901  via an energy feedback clutch  905 . That is, one of the first drive wheel  903  and the second drive wheel  904  is connected to the drive shaft  901  via the energy feedback clutch  905 , while the other one is fixedly connected to the drive shaft. In this embodiment, the first drive wheel  903  and the roller drive wheel  6  are a pair of meshed gears; furthermore, the first drive wheel  903  is connected to the drive shaft  901  via the energy feedback clutch  905 . The energy feedback clutch  905  is a sprag overrun clutch. The second drive wheel  904  can be connected to the lower-speed end of the transmission  8  or the other end other than the high-speed end of the transmission, particularly in the case that the transmission  8  is a multi-stage transmission. In this embodiment, the second drive wheel  904  is a gear meshed with a gear at the lower-end of the transmission  8 . A transition wheel  902  is fixed on the rotary spindle  2 . The transition wheel  902  may be a gear meshed with a gear at the lower-end of the transmission  8 . An electric motor gear  10 , meshed with a gear at the high-speed end of the transmission  8 , is mounted on the output shaft of the electric motor  1  via an electric motor clutch  11 . Of course, the electric motor  1  can be connected to a shaft at the high-speed end of the transmission  8  via the electric motor clutch  11 . 
         [0041]    The working principle of the flywheel energy storage oil pumping machine will be described in brief as below with reference to this embodiment. The oil pumping machine provided by this embodiment is mounted on a pedestal. To begin the operation, start the electric motor  1 , and the rotary spindle  2  will be driven to rotate. A transition wheel is fixed on the rotary spindle  2 . The transition wheel may be a gear meshed with a gear at the lower-end of the transmission  8 . The energy adjustment flywheel  7  is driven via the transmission  8  to rotate by the rotation of the transition wheel. When the rotation speed of the energy adjustment flywheel  7  reaches a set value, under the control of the control device  3 , the clutches  5  begin to act and turn into a joined state from a separated state, so that the rotary spindle  2  is joined with the lifting roller  4 . The lifting roller  4  drives the sucker rod to rise to enter an up stroke. During the up stroke, a part of energy of the energy adjustment flywheel  7  is consumed, and the rotation speed is lowered. When the sucker rod is raised to a predetermined height, the control device  3  instructs the clutches  5  to separate from each other according to a preset program, so that the rotary spindle  2  is separated from the lifting roller  4 . Due to the gravity of the sucker rod, the sucker rod falls to enter a down stroke and drags the lifting roller  4  to drive the roller drive wheel  6  to rotate reversely, so that the roller drive wheel  6  drives the first drive wheel  903  to rotate. Furthermore, the rotation speed of the first drive wheel  903  increases with the increase of the falling speed of the sucker rod. When the rotation speed of the second riving wheel  904  is the same as that of the first drive wheel  903 , due to the overrun clutch, the second drive wheel  904  and the first drive wheel  903  rotate coaxially at the same speed, further to drive the energy adjustment flywheel  7  to rotate faster via the transmission  8 , so that the energy is stored. Meanwhile, the speed of free falling of the sucker rod is controlled, so that the sucker rod falls stably and the impact force of the sucker rod is minimized. The stroke length of the flywheel energy storage oil pumping machine provided by this embodiment is not constricted to the structure due to its structural characteristics, so the flywheel energy storage oil pumping machine is applied to not only oil wells of general stroke length but also oil wells of a stroke above 10 m. 
       Embodiment 2 
       [0042]    Referring to  FIG. 2 , in this embodiment, the energy feedback device  9  is of another structure, and the transmission  8  will be changed in structure with the structure change of the energy feedback device  9 . The energy feedback device  9  comprises a rotating shaft  907 , a first drive wheel  903  and a second drive wheel  904 . The transmission  8  is a multi-stage transmission, and further has a plurality of connecting ends other than the high-speed end and the low-speed end. The connecting shaft of one of the connecting ends is fixedly connected to the rotating shaft  907 . Of course, the rotating shaft  907  may be a part extending from the connecting end. The rotating shaft  907  is connected to the second drive wheel  904  via an energy feedback clutch  905 , wherein, the energy feedback clutch  905  is a sprag overrun clutch. The first drive wheel  903 , the second drive wheel  904  and the roller drive wheel  6  are gears. The first drive wheel  903  is positioned between the roller drive wheel  6  and the second drive wheel  904  and meshed with both the roller drive wheel  6  and the second drive wheel  904 . The first drive wheel  903  is fixed on a drive shaft and able to rotate. The electric motor  1  is connected to a shaft at the high-speed end of the transmission  8  via an electric motor clutch  11 . The remaining is the same as Embodiment 1. 
       Embodiment 3 
       [0043]    Referring to  FIG. 3 , the energy feedback device  9  comprises a drive shaft  901 . The drive shaft  901  is connected to a first drive wheel  903  via an energy feedback clutch  905 . The transmission  8  further has a plurality of connecting ends other than the high-speed end and the low-speed end. The connecting shaft of one of the connecting ends is fixedly connected to the drive shaft  901 . Of course, the drive shaft  901  may be a part extending from the connecting end. The energy feedback clutch  905  is an overrun clutch. The first drive wheel  903  is connected to the roller drive wheel  6  via a driving belt  906 . The remaining is the same as Embodiment 2. 
       Embodiment 4 
       [0044]    Referring to  FIG. 4 , the energy feedback device  9  comprises a drive shaft  901 , a transition wheel  902  fixedly connected to the rotary spindle  2 , and a first drive wheel  903  and a second drive wheel  904  disposed on the drive shaft  901 . The first drive wheel  903  is connected to the drive shaft  901  via an energy feedback clutch  905 . The second drive wheel  904  is directly fixed on the drive shaft  901 . The first drive wheel  903  and the roller drive wheel  6  are a pair of meshed gears. The second drive wheel  904  is connected to the transition wheel  902  via a driving belt  906 . The electric motor  1  is connected to a shaft at the high-speed end of the transmission  8  via an electric motor clutch  11 . The energy generated during lowering the sucker rod passes through the energy feedback device  9 , then passes through the rotary spindle  2  and is transferred to the energy adjustment flywheel  7  via the transmission  8 , to realize the accelerated rotation of the energy adjustment flywheel  7 . The remaining is the same as Embodiment 1. 
       Embodiment 5 
       [0045]    Referring to  FIG. 5 , the energy feedback device  9  comprises a drive shaft  901 , a transition wheel  902  fixedly connected to the rotary spindle  2 , and a first drive wheel  903  and a second drive wheel  904  disposed on the drive shaft  901 . The first drive wheel  903  is connected to the drive shaft  901  via an energy feedback clutch  905 . The second drive wheel  904  and the transition wheel  902  are a pair of meshed gears. The first drive wheel  903  is connected to the roller drive wheel  6  via a driving belt  906 . The remaining is the same as Embodiment 4. 
       Embodiment 6 
       [0046]    Referring to  FIG. 6 , the energy feedback device  9  comprises a drive shaft  901 , a transition wheel  902  fixedly connected to the rotary spindle  2 , and a first drive wheel  903  and a second drive wheel  904  disposed on the drive shaft  901 . The first drive wheel  903  is connected to the drive shaft  901  via an energy feedback clutch  905 . The second drive wheel  904  is directly fixed on the drive shaft  901 . The first drive wheel  903 , the second drive wheel  904  and the roller drive wheel  6  are gears. The first drive wheel  903  is meshed with the roller drive wheel  6 . The transition wheel  902  is provided with internal teeth  902   a.  The second drive wheel  904  is meshed with the internal teeth  902   a.  An electric motor gear  10 , meshed with the internal teeth  902   a,  is mounted on the output shaft of the electric motor  1  via an electric motor clutch  11 . The remaining is the same as Embodiment 4. 
       Embodiment 7 
       [0047]    Referring to  FIG. 7 , the roller drive wheel  6  is a gear. The energy feedback device  9  comprises a drive shaft  901  and an energy feedback clutch  905  disposed on the drive shaft. The transmission  8  at least has a low-speed end and a high-speed end. A connecting shaft at the high-speed end of the transmission  8  is fixedly connected to the drive shaft  901 . The transmission  8  may further have a plurality of connecting ends other than the low-speed end and the high-speed end. The drive shaft  901  may be fixedly connected to the connecting shaft of one of the connecting ends. Of course, the drive shaft  901  may be a part extending from the connecting end. The energy feedback clutch  905  is preferably an overrun clutch. When the energy feedback clutch  905  is an overrun clutch, a first drive wheel, meshed with the roller drive wheel, is mounted on the energy feedback clutch  905 . The remaining is the same as Embodiment 3. 
         [0048]    The foregoing description just illustrates the present invention to enable an ordinary person skilled in the art to implement the solutions perfectly, and is not intend to limit the present invention. For those skilled in the art, various modifications may be made as required without creative efforts to these embodiments after reading the specification. However, these uncreative modifications, as long as within the scope defined by the claims of the present invention, shall be protected by the Patent Law.

Summary:
Disclosed is a flywheel energy storage oil pumping machine, comprising an electric motor ( 1 ) and a control device ( 3 ), and also comprising a rotary spindle ( 2 ), a lifting roller ( 4 ) for lifting an oil sucker rod, a roller drive wheel ( 6 ), an energy adjustment flywheel ( 7 ), a transmission ( 8 ) and an energy feedback device ( 9 ), wherein the lifting roller ( 4 )is sheathed on the rotary spindle ( 2 ), and the separation and reunion between the rotary spindle ( 2 ) and the lifting roller ( 4 ) are achieved via a clutch ( 5 ); the roller drive wheel ( 6 ) is fixedly connected to the lifting roller ( 4 ); and a low-speed end of the transmission ( 8 ) is connected to the rotary spindle ( 2 ), and a high-speed end is connected to the energy adjustment flywheel ( 7 ). The flywheel energy storage oil pumping machine is simple in structure, low in cost, small in size, light in weight, small installation capacity of an electric motor, low in energy consumption, high in efficiency and low in failure rate, and has nearly no pollution in a power grid.