Connecting rod balancing mode of beam-pumping unit

Abstract

The invention relates to a connecting rod balancing mode of a beam-pumping unit, which comprises a connecting rod lower joint, a crank pin bearing seat, a crank pin, a crank, a crank pin bearing cover and a crank pin bearing, the connecting rod balancing structure is characterized in that the connecting rod lower joint or the crank pin bearing seat is connected with a connecting rod balancing box to form the connecting rod balancing structure of the beam-pumping unit, and the connecting rod balancing box is connected with the connecting rod lower joint or the crank pin bearing seat through a flange or a pin shaft. The balance box is arranged at the lower end of the connecting rod or on the crank pin bearing seat, a new balance mode is achieved, the balance weight is arranged at the lower end of the connecting rod or on the crank pin bearing seat, the stress of the crank pin is reduced, the risk of breakage of the crank pin is reduced, and meanwhile the defect that the balance inertia load of the walking beam is large is overcome.

Description

Technical Field

[0001] The invention belongs to the technical field of oil field crude oil exploitation, and in particular relates to a connecting rod balancing method of a walking beam type oil pumping unit. Background Art

[0002] Beam pumping units are essential equipment for crude oil extraction in oilfields. Currently, there are four main balancing methods for beam pumping units: beam balancing, crank balancing, compound balancing, and pneumatic balancing. The first three are mechanically balanced and are the most popular balancing methods. First, beam balancing uses a counterweight at the tail of the beam to balance the load on the rod. Its advantage is that it directly balances the load on the polished rod, reducing stress on the tail shaft, connecting rod, and crankpin, making balance adjustment easy. However, its disadvantages are that the tail shaft and connecting rod assembly are subject to alternating tensile and compressive loads, which can easily cause fatigue. Furthermore, the counterweight carries a large dynamic load, so operating speeds must be limited and the counterweight cannot be too heavy. Otherwise, if the polished rod breaks, the counterweight will move in a near-free fall, causing severe damage to the pumping unit and limiting its use in deep wells with heavy loads. Second, crank balancing uses a counterweight on the reducer crank, which is an indirect balancing method. Its advantages are low dynamic load and good shock resistance, making it suitable for deep wells with heavy loads. The disadvantage is that the connecting rod and crankpin are subjected to great stress. If the crankpin breaks due to fatigue, it will cause serious damage to the entire machine. When adjusting the balance, the crank counterweight needs to be moved. Due to the heavy weight of the counterweight, on-site operation is troublesome and the safety risk is high. 3. Composite balancing: This is a balancing method that distributes the counterweight to both the rocker and the crank. It combines the advantages of both and avoids their disadvantages to a certain extent. However, the crankpin is still subjected to great stress, and crankpin fracture is still the main cause of serious damage. It is also inconvenient to adjust the balance.

[0003] Beam pumping units are characterized by their outdoor operation, heavy loads, and 24 / 7 continuous operation. A failure can cause well production to stop and incur high repair costs. Crankpin fatigue fracture accounts for a significant proportion of serious pumping unit failures, accounting for approximately 30-40%. Therefore, reducing crankpin stress and increasing crankpin reliability are key approaches to reducing failure rates. Optimizing crankpin stress through balancing can reduce the probability of crankpin fracture. Summary of the Invention

[0004] The purpose of the present invention is to overcome the shortcomings of the above-mentioned technology and provide a connecting rod balancing method for a walking beam pumping unit. A connecting rod balancing box is installed at the lower end of the connecting rod of the walking beam pumping unit. The gravity of the connecting rod balancing box directly acts on the connecting rod, thereby reducing the force on the crank pin, optimizing the force state of the crank pin, and reducing the inertia load of the entire machine.

[0005] To achieve the above-mentioned purpose, the present invention adopts the following technical solutions: a connecting rod balancing method for a walking beam pumping unit, including a connecting rod lower joint, a crank pin bearing seat, a crank pin, a crank, a crank pin bearing cover and a crank pin bearing, the connecting rod lower joint and the crank pin bearing seat are fixedly connected to the integral connecting rod crank pin structure, a connecting rod balance box is connected to the connecting rod lower joint or the crank pin bearing seat, forming a connecting rod balancing structure of the walking beam pumping unit, and the connecting rod balance box is connected to the connecting rod lower joint or the crank pin bearing seat through a flange or a pin shaft.

[0006] Furthermore, the connecting rod balancing box is a box body for containing a plurality of small balancing blocks, forming a balancing weight box for placing and taking out small balancing weight blocks to facilitate adjustment of the overall weight.

[0007] Furthermore, the connecting rod balance box is provided with a balance box flange, the inner hole of the balance box flange is larger than the outer conical surface of the crank pin bearing seat, the balance box flange is provided with bolt through holes corresponding to the threaded holes of the connecting rod lower joint flange, the balance box flange is mounted on the outside of the connecting rod lower joint flange, and is fastened to the crank pin bearing seat by bolts, forming a fixed connection structure between the connecting rod balance box and the connecting rod crank pin structure.

[0008] Furthermore, a parallel ear plate is provided on the top of the connecting rod balance box, and a connecting pin hole is provided on the parallel ear plate. The parallel ear plate is pin-connected to the bridge flange, and the bridge flange is fastened to the connecting rod lower joint flange and the crank pin bearing seat by bolts. The inner hole of the bridge flange is larger than the outer circle of the conical surface of the crank pin bearing seat, and a lug is provided under the bridge flange, and a hinge pin hole is provided on the lug. The parallel ear plate on the top of the balancing weight box body is plugged into the bridge flange and pin-connected by a cylindrical pin to form an eccentric pin connection structure of the connecting rod crank pin structure and the balancing weight box.

[0009] Furthermore, a parallel ear plate is provided on the top of the connecting rod balance box, and the parallel ear plate is connected to a double-layer hinge mechanism. The double-layer hinge mechanism includes a balance box bearing, a bearing seat, a balance box connecting plate, an inner bearing pressure cover, an outer bearing pressure cover and a crankpin bearing pressure cover. The crankpin bearing pressure cover is in the shape of a circular stepped platform, and the crankpin bearing pressure cover is fixed to the crankpin bearing seat. The inner ring of the balance box bearing is connected to the stepped platform of the crankpin bearing pressure cover, and the outer ring of the balance box bearing is connected to the inner circle of the balance box connecting plate. The outer bearing pressure cover presses the outer ring of the balance box bearing and is fixed to the balance box connecting plate. The inner bearing pressure cover presses the inner ring of the balance box bearing and is fixed to the crankpin bearing pressure cover. The balance box connecting plate is bolted to the parallel ear plate on the top of the connecting rod balance box to form a concentric pin connection structure of the connecting rod balance box and the connecting rod crankpin structure.

[0010] Beneficial effects: Compared with the prior art, the present invention sets a balance box on the lower end of the connecting rod or the crank pin bearing seat to achieve a new balancing method. The new connecting rod balancing method achieves the purpose of small pumping machine load and simple and convenient balance adjustment. It can also obtain comprehensive optimal performance by scientifically distributing the proportions of walking beam balance, crank balance and connecting rod balance, reduce the inertial load of the whole machine load, and greatly reduce the force on the crank pin. It has the advantages of good energy saving effect, high reliability, low cost, simple installation and adjustment, etc. The balance weight is set at the lower end of the connecting rod, which reduces the force on the crank pin and reduces the risk of crank pin breakage. At the same time, it also avoids the disadvantage of large inertial load of the walking beam balance weight. The present invention can be used for new pumping unit design and can also be used for the modification of existing models. According to different oil well working conditions, the connecting rod balance can be used alone or in combination with the walking beam balance and crank balance to achieve the effect that is most conducive to the operation of the whole machine. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a structural principle diagram of the connecting rod balance of the present invention;

[0012] Figure 2 Schematic diagram of the fixed connection between the connecting rod crank pin structure and the balance weight box in Example 1;

[0013] Figure 3 yes Figure 2 Right view;

[0014] Figure 4 Schematic diagram of the eccentric pin connection between the connecting rod crankpin structure and the balance weight box in Example 2;

[0015] Figure 5 yes Figure 4 Right view;

[0016] Figure 6 Schematic diagram of the concentric pin connection structure between the connecting rod crank pin structure and the balance weight box in Example 3;

[0017] Figure 7 yes Figure 6 Right view;

[0018] Figure 8 It is a schematic diagram of the local structure of the connecting rod crank pin assembly;

[0019] Figure 9 It is the force component diagram of the connecting rod as a two-force rod hinged at both ends;

[0020] Figure 10 This is a schematic diagram of connecting rod force analysis after adding connecting rod balance;

[0021] Figure 11 The load is close to the standard dynamometer diagram;

[0022] Figure 12 It is a comparison curve of the crankpin force calculation results of the connecting rod counterweight and the crankpin force calculation results of the connecting rod counterweight when the crank rotates 5°;

[0023] Figure 13 It is a simplified diagram of a four-bar mechanism;

[0024] Figure 14 This is the comparison curve after calculating the angular acceleration of the connecting rod and the rocker beam when the crank rotates 5°;

[0025] Figure 15 It is the inertia load curve of the walking beam counterweight and the connecting rod counterweight.

[0026] In the figure: 1. Connecting rod, 1-1. Connecting rod lower joint, 1-2. Connecting rod lower joint flange, 2. Crank pin bearing seat, 3. Crank pin, 4. Crank, 5. Crank pin bearing cover, 6. Crank pin bearing, 7. Connecting rod balance box, 7-1. Balance box flange, 8. Oil beam, 9. Donkey head, 10. Bracket, 11. Bridge flange, 12. Cylindrical pin, 14. Connecting bearing, 15. Bearing seat, 16. Balance box connecting plate, 17. Bearing inner pressure cover, 18. Bearing outer pressure cover. DETAILED DESCRIPTION

[0027] In order to be able to more clearly understand the above-mentioned objects, features and advantages of the present invention, the present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that, in the absence of conflict, the embodiments of the present application and the features in the embodiments can be combined with each other. In the following description, many specific details are set forth in order to fully understand the present invention, and the embodiments described are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by technicians in the technical field of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0028] In the various embodiments of the present invention, for ease of description and not limitation, the term "connection" used in the patent application specification and claims is not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "below," "left," and "right" are used solely to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship also changes accordingly.

[0029] See attached for details Figure 1This embodiment provides a balancing method for a walking beam pumping unit, including an oil beam 8, a donkey head 9, a bracket 10, a connecting rod 1, a crank pin bearing seat 2, a crank pin 3, a crank 4, a crank pin bearing cap 5 and a crank pin bearing 6. The connecting rod lower joint and the crank pin bearing seat are fixedly connected to the integral connecting rod crank pin structure. A connecting rod balance box 7 is connected to the connecting rod lower joint 1-1 or the crank pin bearing seat 2, forming a connecting rod balancing structure of the walking beam pumping unit. The connecting rod balance box is connected to the connecting rod lower joint or the crank pin bearing seat through a flange or a pin shaft.

[0030] A preferred solution of this embodiment is that the connecting rod balancing box is a box body for containing a plurality of small balancing blocks, forming a balancing weight box for placing and removing small balancing weight blocks to facilitate adjustment of the overall weight.

[0031] like Figure 8 As shown, the connecting rod crankpin assembly structure includes a connecting rod lower joint 1-1, a crankpin bearing seat 2, a crankpin 3, a crank 4, a crankpin bearing cap 5, and a crankpin bearing 6. The crankpin bearing seat has an outer conical surface, the large end of which is provided with a flange. The flange is provided with a threaded hole corresponding to the through-hole of the connecting rod lower joint flange. The crankpin bearing is fixedly connected to the crankpin, and the crankpin is fixedly connected to the crank thread through its outer conical surface. The connecting rod lower joint is a special flange. The inner hole of the flange is a tapered hole that matches the outer conical surface of the crankpin bearing seat. The inner hole is surrounded by concentrically arranged through-holes corresponding to the threaded holes of the crankpin bearing seat flange. During structural assembly, the inner conical hole of the lower joint flange is pressed and fixed to the outer conical surface of the crankpin bearing seat with bolts, thereby hingedly connecting the connecting rod lower joint and the crankpin to form an integral connecting rod crankpin structure. The connecting rod crankpin structure is prior art and will not be described in detail. The key point of the present invention is the connection of the connecting rod balance box to the connecting rod crankpin structure, specifically, the connection of the connecting rod balance box to the connecting rod lower joint 1-1 of the connecting rod crankpin structure, or the connection of the connecting rod balance box to the crankpin bearing. Because the connecting rod lower joint and the crankpin bearing seat are fixedly connected to form the aforementioned connecting rod crankpin structure, the balance weight box is equivalently connected to either the connecting rod lower joint or the crankpin bearing seat. It is important to note that the connecting rod balance box is not connected to the crank.

[0032] Example 1

[0033] See attached for details Figure 2-3 The connecting rod balance box is provided with a balance box flange 7-1. The inner hole of the balance box flange is larger than the outer conical surface of the crank pin bearing seat. The balance box flange is provided with bolt through holes corresponding to the threaded holes of the connecting rod lower joint flange 1-2. The balance box flange is sleeved on the outside of the connecting rod lower joint flange and is fastened to the crank pin bearing seat by bolts to form a fixed connection structure between the connecting rod balance box and the connecting rod crank pin structure.

[0034] Example 2

[0035] See attached for details Figure 4-5 A parallel ear plate is provided on the top of the connecting rod balance box, and a connecting pin hole is provided on the parallel ear plate. The parallel ear plate is pinned to the bridge flange 11, and the bridge flange is fastened to the connecting rod lower joint flange and the crank pin bearing seat by bolts. The inner hole of the bridge flange is larger than the outer circle of the conical surface of the crank pin bearing seat. A lug is provided at the bottom of the bridge flange, and a hinge pin hole is provided on the lug. The parallel ear plate on the top of the balancing weight box body is plugged into the bridge flange and pinned by a cylindrical pin 12 to form an eccentric pin connection structure of the connecting rod crank pin structure and the balancing weight box.

[0036] Example 3

[0037] See attached for details Figure 6-7 , the preferred solution of this embodiment is: a parallel ear plate 7-2 is provided on the top of the connecting rod balance box, and the parallel ear plate is connected to a double-layer hinge mechanism, and the double-layer hinge mechanism includes a balance box bearing 14, a bearing seat 15, a balance box connecting plate 16, a bearing inner pressure cover 17, a bearing outer pressure cover 18 and a crankpin bearing pressure cover 5, and the crankpin bearing pressure cover is in the shape of a circular stepped platform, and the crankpin bearing pressure cover is fixed to the crankpin bearing seat, and the inner ring of the balance box bearing is connected to the stepped platform of the crankpin bearing pressure cover, and the outer ring of the balance box bearing is connected to the inner circular groove of the balance box connecting plate, the outer pressure cover of the bearing presses the outer ring of the balance box bearing and is fixed to the balance box connecting plate, the inner pressure cover of the bearing presses the inner ring of the balance box bearing and is fixed to the crankpin bearing pressure cover, and the balance box connecting plate is bolted to the parallel ear plate on the top of the connecting rod balance box to form a concentric pin connection structure of the connecting rod balance box and the connecting rod crankpin structure.

[0038] Design principle of connecting rod balance

[0039] The core of connecting rod balancing technology is to install a balancing weight box at the lower end of the connecting rod. There are three main ways to connect the connecting rod balancing box:

[0040] Direct connection: The counterweight box is directly fixed to the connecting rod lower joint or crankpin bearing seat. This method of counterweight box has an additional bending moment on the connecting rod and is suitable for working conditions where the counterweight box is not too heavy.

[0041] Eccentrically hinged: The counterweight box is hinged to a connecting plate, which is fixed to the connecting rod's lower joint or crankpin bearing seat. This type of counterweight box produces minimal additional bending moment on the connecting rod and is suitable for most operating conditions.

[0042] Concentric articulation: The counterweight box is articulated to the connecting rod lower joint or crankpin bearing seat, with the articulation center concentric with the crankpin axis. This method of counterweight box does not generate additional bending moment on the connecting rod and is suitable for working conditions with large counterweight boxes.

[0043] The calculation data of the present invention for reducing the inertial load of the entire vehicle:

[0044] The present invention evenly distributes the proportions of the walking beam balance, crank balance, and connecting rod balance to achieve comprehensive optimal performance, reduce the inertial load of the entire dynamic load, and significantly reduce the force on the crank pin. This is further illustrated by mechanical calculations.

[0045] 1. When the balancing effect is the same, connecting rod balancing can reduce the crankpin force compared to crank balancing:

[0046] The tension on the connecting rod generated by the crank counterweight is transmitted to the connecting rod via the crankpin. However, with connecting rod balancing, which involves placing a counterweight at the lower end of the connecting rod, a portion of the connecting rod tension is provided directly by the counterweight, bypassing the crankpin. Therefore, while achieving the same balancing effect, connecting rod balancing can reduce the crankpin force compared to crank balancing. In principle, if the crank counterweight is removed, the crankpin only transmits the tension on the connecting rod generated by the net torque of the reducer, resulting in much less stress on the crankpin. In actual design, since crank balancing can achieve a greater balancing torque with less weight by adjusting the position of the counterweight, some crank balancing can be retained, reducing the size of the connecting rod counterweight box and facilitating space layout.

[0047] Since the connecting rod balance does not change the parameters of the four-bar mechanism, it can be considered that the crank balance effect is the same, which means that the tension P of the connecting rod on the rocker beam is L constant.

[0048] See attached for details Figure 9 , take the connecting rod as the research object, and its deadweight is negligible. Before adding the connecting rod balance box, the connecting rod is a two-force rod hinged at both ends. The two ends are respectively subjected to the tension of the tail shaft and the crank pin. The two forces are equal in magnitude and opposite in direction, so the crank pin is subjected to force F 销 for:

[0049] F 销 =P L ,

[0050] Where: P L is the pulling force of the tail shaft on the connecting rod.

[0051] After adding a balance weight to the lower end of the connecting rod, the force analysis is as follows Figure 10 As shown, assuming that its gravity is Q 连 , the distance from the force point to the crank pin is L P , the angle between the connecting rod and the plumb bob is α 连 ,

[0052] Taking the moment of the crank pin, the connecting rod balance weight forms an additional bending moment M on the connecting rod. 附 , the tail shaft normal force P Lt To balance:

[0053] Q 连 .L P .sinα 连 =PLt L

[0054] Due to L P Much smaller than the connecting rod length L, α 连 Generally it does not exceed 17°, so if the weight of the connecting rod balance box is not large, the additional bending moment can be ignored. 曲 for:

[0055] F 曲 =P Lz -Q 连 cosα 连

[0056] (Note: If the additional bending moment cannot be ignored, the structural design can adopt a method in which the hinge point of the balance box and the lower end of the connecting rod is concentric with the crank pin, that is, Lp = 0, which completely eliminates the additional bending moment of the balance box on the connecting rod.)

[0057] From the above calculations, it can be seen that the connecting rod balancing technology can significantly reduce the force on the crank pin.

[0058] Example

[0059] See the attached standard indicator diagram for details. Figure 11 Substituting the design parameters for a CYJ12-6-73HF composite balanced pumping unit into the design example, the relevant parameters are as follows: R = 1510mm, A = 5500mm, C = 2930mm, P = 5840mm, H = 5702mm, and I = 3065mm. The distance from the connecting rod counterweight to the crankpin center is designed to be Lp = 300mm. The equivalent counterweight of the crank is reduced by 20kN, and the connecting rod counterweight is 20kN. Assuming the maximum load Pmax = 100kN and the minimum load Pmin = 60kN at the donkey head suspension point, the loads are close to the standard dynamometer diagram.

[0060] Comparison curves such as Figure 12 As shown in the figure, the crankpin forces with and without connecting rod counterweights are calculated for every 5° rotation of the crank. It can be seen that the connecting rod counterweight can significantly reduce the crankpin forces, with an average reduction of about 20kN, a decrease of 10.4%, thereby reducing the risk of crankpin fracture and extending the service life of the crankpin.

[0061] 2. When the balancing effect is the same, the connecting rod balance can reduce the overall dynamic load compared to the walking beam balance:

[0062] Beam balancing achieves balance by adding a counterweight to the end of the beam. Because the beam swings widely and reciprocates, the angular acceleration varies significantly, resulting in a high inertial load on the crank counterweight. Connecting rod balancing, on the other hand, achieves the same balancing effect, but because the connecting rod swings more narrowly, with the lower end showing the greater swing, results in a lower dynamic load and a lower center of gravity, contributing to stable operation of the entire machine. The following calculations illustrate this point.

[0063] like Figure 13 As shown, the walking beam pumping unit is a typical four-bar simplified mechanism.

[0064] We use the vector method for calculation. The four rods crank, connecting rod, rocker arm and base rod R, P, C, K can be expressed as: For the convenience of analysis, the positive directions of the angles in the figure are defined as follows:

[0065] The crank angle θ is measured from the 12 o'clock position and is positive in the clockwise direction;

[0066] The reference angles θ2, θ3, θ4, etc. of each rod are all measured from the base rod OO1 and are positive in the counterclockwise direction.

[0067] The geometric dimensions of each rod are specified as follows: R—crank pin rotation radius, P—connecting rod length, C—swinging beam rear arm length, K—base rod length, A—swinging beam front arm length, I—base rod horizontal projection length.

[0068] Among them, the only active variable is θ2, and the other variables are intermediate variables.

[0069] The geometric relationship in the figure is:

[0070]

[0071] θ2=2π-θ+α

[0072]

[0073]

[0074] In the figure, the relationship between the vectors is:

[0075]

[0076] It can be expressed as a complex vector:

[0077]

[0078] (Because the angle between K and base rod OO1 is fixed at 0, there is no coefficient.)

[0079] Derivative of both sides of the above equation with respect to time:

[0080]

[0081] According to Euler's formula e iθ =cosθ+isinθ, the above formula can be rewritten as:

[0082] Rθ2icosθ2-Rθ2sinθ2+Pθ3icosθ3-Pθ3sinθ3βCθ4icosθ4-Cθ2sinθ4

[0083] Let the real and imaginary parts of both sides be equal, and we get the system of equations:

[0084] Rθ2cosθ2+Pθ3cosθ3=Cθ4cosθ4

[0085] Rθ2sinθ2+Pθ3sinθ3=Cθ2sinθ4

[0086] Solve the equations and take the derivative to get the angular velocity of the connecting rod and the rocker beam. for

[0087] Taking the derivatives of the above two equations with respect to time, we can get the angular acceleration of the connecting rod and the rocker beam. and

[0088] Where,

[0089] Since the crank rotates at a constant speed, but and for:

[0090]

[0091] The velocity of the center of gravity V and the acceleration a of the walking beam counterweight can be calculated by the following formula:

[0092]

[0093] The center of gravity velocity VQ of the connecting rod counterweight can be calculated by the following formula:

[0094] The velocity of point A at the connecting rod crankpin is ωR, and its direction is perpendicular to the crank. According to the four-bar linkage parameter diagram and the law of rigid body plane motion, the velocity components of points A, B, and Q along the connecting rod direction are equal, which can be expressed as:

[0095]

[0096] Similarly, the velocity component of point A in the direction perpendicular to the connecting rod is:

[0097]

[0098] The velocity component of point B in the direction perpendicular to the connecting rod is:

[0099]

[0100] According to the plane motion of the rigid body, the velocity component of point Q in the vertical direction of the connecting rod can be obtained as:

[0101]

[0102] Obviously, the absolute velocity value V at point Q Q for:

[0103]

[0104] The acceleration of the center of gravity Q of the connecting rod balance weight is decomposed into the connecting rod direction and the connecting rod vertical direction, which can be used to calculate V QP and V QT Take the derivative and then calculate its absolute acceleration a Q for:

[0105]

[0106] 3. Through calculation, we know that if the connecting rod balance is used to achieve the same balancing effect as the walking beam balance, that is, the inertia load of the two is compared under the condition that the moments about the center axis are equal, the inertia load of the connecting rod balance is much smaller than that of the walking beam balance.

[0107] Substituting the static analysis above for the design example of a CYJ12-6-73HF pumping unit, R = 1510mm, A = 5500mm, C = 2930mm, P = 5840mm, H = 5702mm, I = 3065mm, and Lp = 300mm, we assume the beam counterweight is 20kN. We design the connecting rod counterweight to be 27.3kN, assuming the moment about the center axis is equal.

[0108] See attached for details Figure 14 Calculate the angular acceleration of the connecting rod and the rocker beam for every 5° rotation of the crank, and you can get the comparison curve

[0109] The calculation results show that the maximum angular acceleration of the connecting rod is 0.04m / s 2 , only the maximum angular acceleration of the rocker beam is 0.13m / s 2 One third of .

[0110] Further calculate the center of gravity acceleration of the beam counterweight and the connecting rod counterweight. According to the acceleration formula, the inertia load curve comparison of the beam counterweight and the connecting rod counterweight can be calculated. Figure 15 :

[0111] The calculation results show that if the same balancing effect is achieved, the maximum inertia load of the connecting rod counterweight is only 0.04kN, while the maximum inertia load of the walking beam counterweight is 1.07kN. Compared with the inertia load of the connecting rod counterweight, it can be ignored.

[0112] Because the counterweight is located at the lower end of the connecting rod, it acts similarly to a beam balance, directly balancing the load on the polished rod. This reduces the stress on the crankpin and the risk of crankpin breakage, while also avoiding the drawback of the large inertial load of the beam balance. To facilitate manufacturing and installation, the counterweight at the lower end of the connecting rod is designed as a box structure with an internal counterweight block connected to the lower end of the connecting rod, making overall manufacturing, installation, and balance adjustment simple and convenient.

[0113] The above-mentioned detailed description of the optimal configuration structure of the balance block of a walking beam pumping unit with reference to the embodiment is illustrative rather than restrictive. Several embodiments can be listed according to the limited scope. Therefore, changes and modifications without departing from the overall concept of the present invention should fall within the scope of protection of the present invention.

Claims

1. A connecting rod balancing system for a beam pumping unit, comprising a connecting rod lower joint, a crankpin bearing seat, a crankpin, a crank, a crankpin bearing cap, and a crankpin bearing, wherein the connecting rod lower joint and the crankpin bearing seat are fixedly connected to form an integral connecting rod crankpin structure, characterized in that: The connecting rod lower joint or crank pin bearing seat is connected to a connecting rod balance box to form a connecting rod balance structure of the walking beam pumping unit. The connecting rod balance box is connected to the connecting rod lower joint or crank pin bearing seat through a flange or a pin shaft.

2. The connecting rod balancing method of the beam pumping unit according to claim 1 is characterized by: The connecting rod balancing box is a box body for containing a plurality of small balancing blocks, forming a balancing weight box for placing and taking out small balancing weight blocks to facilitate adjustment of the overall weight.

3. The connecting rod balancing method of the beam pumping unit according to claim 1 or 2, characterized in that: The connecting rod balance box is provided with a balance box flange, the inner hole of the balance box flange is larger than the outer conical surface of the crank pin bearing seat, the balance box flange is provided with bolt through holes corresponding to the threaded holes of the connecting rod lower joint flange, the balance box flange is sleeved on the outside of the connecting rod lower joint flange, and is fastened to the crank pin bearing seat by bolts, forming a fixed connection structure between the connecting rod balance box and the connecting rod crank pin structure.

4. The connecting rod balancing method of the beam pumping unit according to claim 1 or 2, characterized in that: A parallel ear plate is provided on the top of the connecting rod balance box, a connecting pin hole is provided on the parallel ear plate, a lug is provided on the lower end of the connecting rod lower joint flange, a hinge pin hole is provided on the lug, the parallel ear plate is plugged into the connecting rod lower joint flange and connected by a cylindrical pin to form an eccentric pin connection structure between the connecting rod balance box and the connecting rod crank pin structure.

5. The connecting rod balancing method of the beam pumping unit according to claim 1 or 2, characterized in that: The connecting rod balance box is provided with a parallel ear plate on the top, and the parallel ear plate is connected to the double-layer hinge mechanism. The double-layer hinge mechanism includes a balance box bearing, a bearing seat, a balance box connecting plate, an inner bearing pressure cover, an outer bearing pressure cover and a crankpin bearing pressure cover. The crankpin bearing pressure cover is in the shape of a circular stepped platform. The crankpin bearing pressure cover is fixed to the crankpin bearing seat. The inner ring of the balance box bearing is connected to the stepped platform of the crankpin bearing pressure cover. The outer ring of the balance box bearing is connected to the inner circle of the balance box connecting plate. The outer bearing pressure cover presses the outer ring of the balance box bearing and is fixed to the balance box connecting plate. The inner bearing pressure cover presses the inner ring of the balance box bearing and is fixed to the crankpin bearing pressure cover. The balance box connecting plate is bolted to the parallel ear plate on the top of the connecting rod balance box to form a concentric pin connection structure of the connecting rod balance box and the connecting rod crankpin structure.

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