Pumping unit based on permanent magnet type magnetic lead screw motor

Abstract

The invention relates to the technical field of oil extraction equipment, in particular to an oil pumping unit based on a permanent magnet type magnetic lead screw motor, which comprises a magnetic lead screw motor, a controller and an oil well pump, and is characterized in that a magnetic lead screw nut and a permanent magnet synchronous rotating motor rotor form a common rotating part of the magnetic lead screw motor; the rotating part is coaxially sleeved outside the magnetic lead screw rotor and is positioned between the stator and the rotor; and the controller is used for driving the rotor to rotate, converting rotary motion into linear reciprocating motion of the rotor through the magnetic lead screw, and driving the oil well pump to lift crude oil. Direct non-contact conversion of rotation linear motion is achieved through the permanent magnet type magnetic lead screw motor, friction loss and inertia loads caused by multi-stage transmission are avoided, the transmission efficiency of the system is greatly improved, under the condition that the same lifting work is completed, electric energy consumption can be effectively reduced, and the energy-saving effect is obvious.

Description

Technical Field

[0001] This invention relates to the field of oil production equipment technology, specifically to an oil pumping unit based on a permanent magnet screw motor. Background Technology

[0002] Currently, the most commonly used oil extraction machinery in the petroleum industry is the beam pumping unit. This type of pumping unit uses a four-bar linkage to convert the rotary motion of the electric motor into the linear reciprocating motion of the suspension point.

[0003] However, the structural characteristics of this mechanism also lead to inherent limitations: on the one hand, the long transmission chain, joint friction and inertial load result in generally low transmission efficiency and high energy loss; on the other hand, the stroke length of the suspension point is limited by the geometric dimensions of the mechanism, so the stroke of the beam pumping unit is generally small.

[0004] With the continuous development of my country's oilfields, the extraction environment is becoming increasingly complex. In particular, with the increase in the number of high-viscosity oil wells, high-water-cut oil wells, low-production oil wells and offshore oil wells, as well as the continuous deepening of oil reservoirs, the demand for more efficient and longer-stroke pumping units is becoming increasingly urgent.

[0005] In recent years, in order to solve the above problems, some scholars have proposed a solution to replace the rotary motor in the submersible electric pump with a linear motor. These solutions abandon the complex energy conversion path of "rotary motor-mechanical transmission-linear motion" and instead use a linear motor to directly drive the double-acting reciprocating oil pump, realizing the direct conversion of electrical energy into linear mechanical energy and improving the efficiency and stability of the system.

[0006] However, due to the inherent defects of linear motor drive schemes, such as low output thrust and low thrust density, oil pumping unit systems driven by linear motors often have problems such as excessive size, high cost and limited thrust, making these schemes difficult to promote. Summary of the Invention

[0007] The purpose of this invention is to address the shortcomings of existing technologies by providing an oil pumping unit based on a permanent magnet magnetic screw motor. By introducing a permanent magnet magnetic screw, electrical energy is directly converted into mechanical energy for linear reciprocating motion, thereby improving transmission efficiency, reducing oil pumping energy consumption, and enhancing output thrust.

[0008] The technical solution of this invention is: an oil pumping unit based on a permanent magnet lead screw motor, comprising: A magnetic lead screw consists of a nut and a mover, with the mover coaxially disposed inside the nut and there is no mechanical contact between the two. A permanent magnet synchronous rotary motor includes a stator and a rotor. The rotor is connected to a nut and forms a common rotating part of a magnetic screw motor. This rotating part is coaxially sleeved outside the mover. An oil pump is connected to one end of the mover; The controller is used to drive the rotor to rotate and convert the rotational motion into the linear reciprocating motion of the mover through the magnetic lead screw, thereby driving the oil pump to work.

[0009] Preferably, the permanent magnet synchronous rotary motor further includes a housing, with a front end cover and a rear end cover detachably and sealed at both ends of the housing, the stator being fixedly installed inside the housing, and the rotor being connected to the housing via a set of thrust bearings.

[0010] Preferably, the mover includes a mover screw and a helically distributed first permanent magnet, the first permanent magnet being attached to the outer surface of the mover screw; the nut includes a nut yoke and a helically distributed second permanent magnet, the second permanent magnet being attached to the inner surface of the nut yoke; the nut yoke and the mover screw are coaxially arranged, with an annular air gap between them.

[0011] Preferably, both the first permanent magnet and the second permanent magnet are radially magnetized, with their N and S magnetic poles arranged alternately along the axial direction periodically, and no gaps are left between the magnetic poles.

[0012] Preferably, the first and second permanent magnets are made of neodymium iron boron. The thrust is zero when any magnetic pole on the first permanent magnet is axially opposite to the corresponding magnetic pole on the second permanent magnet, and the thrust is maximum when the relative displacement between the two magnetic poles is half a pole pitch.

[0013] Preferably, both the moving screw and the nut yoke are made of magnetically conductive material, thereby forming a low magnetic resistance magnetic path, providing a closed loop path for the magnetic field coupled between the first permanent magnet and the second permanent magnet. Both the nut yoke and the second permanent magnet are ring structures.

[0014] Preferably, the pole distance, width, and rotation direction of the first and second permanent magnets are consistent.

[0015] Preferably, the magnetic screw nut is rigidly connected to the rotor of the permanent magnet synchronous rotary motor, together forming the rotating part of the magnetic screw motor and performing synchronous rotational motion.

[0016] Preferably, a sealing gasket is press-fitted to the bottom of the thrust bearing. The sealing gasket is used to assist in the positioning of the thrust bearing and to achieve static sealing.

[0017] Preferably, the controller is used to acquire the position and angle signals of the mover and the rotor, calculate the reference angular position of the rotor based on the deviation between the target position and the current position of the mover, and output a control signal to the driver through current loop control, so that the stator generates the rotating magnetic field required to drive the rotor, thereby controlling the rotor to rotate, so as to realize the closed-loop control of the linear reciprocating motion of the mover.

[0018] Compared with the prior art, the present invention has the following advantages: This invention eliminates the complex mechanical conversion links such as the four-bar linkage, gearbox, and belt drive in traditional beam pumping units. It achieves direct, contactless conversion of "rotational-linear" motion through a permanent magnet screw motor, avoiding frictional losses and inertial loads caused by multi-stage transmission. The system transmission efficiency is greatly improved, and under the condition of completing the same lifting work, it can effectively reduce power consumption and achieve significant energy saving. The magnetic screw structure, which is composed of a helical distribution of permanent magnets, directly converts the rotational torque into axial thrust through magnetic field coupling. Its thrust density can be several times that of a conventional linear motor of the same volume, overcoming the inherent defects of low thrust and large size of linear motors. It is particularly suitable for mining scenarios such as deep wells and heavy oil wells that require large thrust and long stroke. The permanent magnet synchronous rotary motor and magnetic lead screw are integrated into a single rotating part, resulting in a compact overall structure and small axial dimension, facilitating downhole installation and layout. The power transmission process involves no mechanical contact, resulting in low wear, low noise, long service life, and no need for lubrication or maintenance, making it suitable for harsh downhole working environments.

[0019] This invention improves performance while simplifying the structure, reducing maintenance costs, and keeping overall manufacturing costs under control. It is particularly suitable for oilfield development where energy efficiency, thrust, and reliability are critical, and has promising prospects for industrialization and economic benefits. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the axial cross-sectional structure of a permanent magnet lead screw motor. Figure 3 This is a partial structural diagram of the magnetic lead screw, showing the magnet layout of the mover and nut; In the diagram: 1. Housing, 2. Stator, 3. Rotor, 4. Front cover, 5. Rear cover, 6. Nut, 7. Mover, 8. Thrust bearing, 9. Sealing gasket, 10. Controller, 11. Oil pump; 31. Nut yoke, 32. Second permanent magnet, 71. Moving screw, 72. First permanent magnet. Detailed Implementation

[0021] The present invention will be further described below with reference to the accompanying drawings and embodiments. Example 1

[0022] like Figure 1 and Figure 2As shown, an oil pumping unit based on a permanent magnet screw motor includes a housing 1, a stator 2, a rotor 3, a front end cover 4, a rear end cover 5, a nut 6, a mover 7, a thrust bearing 8, a sealing gasket 9, a controller 10, and an oil pump 11.

[0023] The housing 1 is made of duplex steel with corrosion resistance and high strength. It is cylindrical in shape and contains stator 2, rotor 3 and nut 6. The stator 2, rotor 3 and nut 6 are coaxially arranged with the housing 1.

[0024] Both the front cover 4 and the rear cover 5 are made of stainless steel and are fastened to both ends of the housing 1 by multiple circumferentially arranged fasteners to form an installation chamber. The fasteners can be bolts or screws.

[0025] like Figure 1 As shown, the permanent magnet synchronous rotary motor includes a stator 2 and a rotor 3. The stator 2 is located on the outer layer of the rotor 3. The rotor 3 is rigidly connected to the nut 6 of the magnetic screw, together forming the rotating part of the magnetic screw motor. This rotating part is supported and installed in the housing 1 by a thrust bearing 8, and is coaxially sleeved on the outside of the mover 7.

[0026] like Figure 1 As shown, the magnetic lead screw includes a nut 6 and a mover 7. The mover 7 is located in the innermost layer. It passes through the internal through hole of the nut 6 and extends to both sides of the front end cover 4 and the rear end cover 5, but does not make mechanical contact with the nut 6. The lower end of the mover 7 is rigidly connected to the oil pump 11 through a connector. The connection method is a flange connection.

[0027] The magnetic lead screw converts the rotational mechanical energy transmitted from the permanent magnet synchronous rotary motor into linear mechanical energy output. The magnetic lead screw and the permanent magnet synchronous rotary motor together form a magnetic lead screw motor.

[0028] like Figure 3 As shown, the mover 7 includes a mover screw 71 and a first permanent magnet 72. The mover screw 71 is a solid cylinder, and the first permanent magnet 72 is attached to the outer surface of the mover screw 71 in a spiral shape. The nut 6 is composed of a nut yoke 31 and a second permanent magnet 32, both of which are hollow annular structures. The second permanent magnet 32 ​​is also arranged in a spiral shape and attached to the inner surface of the nut yoke 31. Its pole distance, width and direction of rotation are consistent with those of the first permanent magnet 72.

[0029] The nut yoke 31 and the moving screw 71 are both made of magnetically conductive materials with a certain rigidity, such as low-carbon steel, to provide a path for the closed loop of magnetic lines of force.

[0030] Both the first permanent magnet 72 and the second permanent magnet 32 ​​are made of neodymium iron boron material and are magnetized radially. The N and S magnetic poles of the permanent magnets are arranged alternately along the axial direction periodically, and there are no gaps between the magnetic poles. The annular space between the first permanent magnet 72 and the second permanent magnet 32 ​​forms a uniform working air gap.

[0031] like Figure 3 As shown, the thrust bearing 8 is a double-direction thrust ball bearing, which is installed at both ends of the axial direction of the rotating part of the magnetic screw motor to bear the axial reaction force generated when the mover 7 moves linearly; a sealing gasket 9 is press-fitted at the bottom of the thrust bearing 8 near the mover screw. The sealing gasket 9 is made of fluororubber material to achieve static sealing between it and the mover screw 71, preventing downhole media from entering the motor.

[0032] The controller 10 is installed behind the rear cover 5 and is connected to the motor and power supply via cables. It is responsible for driving and controlling the entire system. When the controller is working, it drives the motor rotor to rotate according to a preset strategy. Through the coupling effect of the helical magnetic field between the second permanent magnet and the first permanent magnet, the rotating electromagnetic torque is directly converted into axial thrust, thereby driving the oil pump fixed to the mover to perform linear reciprocating motion and complete the lifting of crude oil.

[0033] The specific work process is as follows: After the system is powered on, the controller 10 first completes the system self-test and initialization, drives the mover 7 to the mechanical zero position, and sets its target motion law through internal program or external command; After entering steady-state operation, the controller system collects the position of the mover 7 and the angle of the rotor 3 in real time. Based on the position deviation and the pitch of the magnetic screw, it calculates the reference angular position of the rotor 3. Then, the control algorithm tracks and calculates the reference position angle, outputting a q-axis reference current command (d-axis set to zero) to generate the required electromagnetic thrust. Then, through the built-in current loop controller, such as a PI controller, it calculates the required voltage control quantity based on the difference between the reference current and the feedback current. The controller 10 generates a corresponding control signal based on the calculated voltage control quantity, driving the stator 2 of the permanent magnet synchronous rotary motor to generate a rotating magnetic field, thereby causing the rotor 3 to rotate. After each control cycle ends, a stop command is checked. If no stop command is found, the above control cycle continues to ensure that the mover 7 moves according to the set pattern. If a stop command is found, the mover 7 is controlled to return smoothly to the zero position, and then the system is shut down in an orderly manner. In this way, in the working state, the controller 10 realizes stable and automated control of the linear reciprocating motion of the mover 7, thereby completing the work of lifting underground crude oil to the surface.

[0034] This invention solves the problems of low transmission efficiency and poor stability caused by the complex mechanical transmission of traditional beam pumping units by introducing a permanent magnet magnetic screw motor. At the same time, it overcomes the shortcomings of low thrust density and small output force of linear motor drive schemes, thereby improving the working efficiency, output thrust and operation stability of the pumping unit system.

[0035] This invention is not limited to the embodiments described above. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of this invention, and the changed content still falls within the protection scope of this invention.

Claims

1. An oil pumping unit based on a permanent magnet lead screw motor, characterized in that: include: A magnetic lead screw consists of a nut and a mover, with the mover coaxially disposed inside the nut and there is no mechanical contact between the two. A permanent magnet synchronous rotary motor includes a stator and a rotor. The rotor is connected to a nut and forms a common rotating part of a magnetic screw motor. This rotating part is coaxially sleeved outside the mover. An oil pump is connected to one end of the mover; The controller is used to drive the rotor to rotate and convert the rotational motion into the linear reciprocating motion of the mover through the magnetic lead screw, thereby driving the oil pump to work.

2. The oil pumping unit based on a permanent magnet lead screw motor according to claim 1, characterized in that: The permanent magnet synchronous rotary motor also includes a housing, with a front cover and a rear cover detachably and sealed at both ends of the housing. The stator is fixedly installed inside the housing, and the rotor is connected to the housing through a set of thrust bearings.

3. The oil pumping unit based on a permanent magnet lead screw motor according to claim 1, characterized in that: The mover includes a mover screw and a first permanent magnet arranged in a spiral pattern, the first permanent magnet being attached to the outer surface of the mover screw; the nut includes a nut yoke and a second permanent magnet arranged in a spiral pattern, the second permanent magnet being attached to the inner surface of the nut yoke; the nut yoke and the mover screw are coaxially arranged, with an annular air gap between them.

4. The oil pumping unit based on a permanent magnet lead screw motor according to claim 3, characterized in that: Both the first and second permanent magnets are radially magnetized, with their N and S magnetic poles arranged alternately along the axial direction periodically, and no gaps between the magnetic poles.

5. An oil pumping unit based on a permanent magnet lead screw motor according to claim 4, characterized in that: The first and second permanent magnets are made of neodymium iron boron. The thrust is zero when any magnetic pole on the first permanent magnet is axially opposite to the corresponding magnetic pole on the second permanent magnet. The thrust is maximum when the relative displacement between the two magnetic poles is half a pole pitch.

6. The oil pumping unit based on a permanent magnet lead screw motor according to claim 3, characterized in that: Both the moving screw and the nut yoke are made of magnetically conductive material, thus forming a low magnetic resistance magnetic path, providing a closed loop path for the magnetic field coupled between the first permanent magnet and the second permanent magnet. Both the nut yoke and the second permanent magnet are ring structures.

7. An oil pumping unit based on a permanent magnet lead screw motor according to claim 3, characterized in that: The pole distance, width, and rotation direction of the first and second permanent magnets are consistent.

8. An oil pumping unit based on a permanent magnet lead screw motor according to claim 3, characterized in that: The magnetic lead screw nut is rigidly connected to the rotor of the permanent magnet synchronous rotary motor, together forming the rotating part of the magnetic lead screw motor and performing synchronous rotational motion.

9. An oil pumping unit based on a permanent magnet lead screw motor according to claim 2, characterized in that: A sealing gasket is press-fitted to the bottom of the thrust bearing. The sealing gasket is used to assist in the positioning of the thrust bearing and to achieve static sealing.

10. An oil pumping unit based on a permanent magnet lead screw motor according to claim 1, characterized in that: The controller is used to collect the position and angle signals of the mover and the rotor, calculate the reference angular position of the rotor based on the deviation between the target position and the current position of the mover, and output a control signal to the driver through current loop control, so that the stator generates the rotating magnetic field required to drive the rotor, thereby controlling the rotor to rotate, so as to realize the closed-loop control of the linear reciprocating motion of the mover.

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