A beam-pumping unit's connecting rod balancing mechanism

Abstract

This utility model relates to a connecting rod balancing mechanism for a beam pumping unit, comprising a lower connecting rod joint, a crank pin bearing housing, a crank pin, a crank, a crank pin bearing cover, and a crank pin bearing. The lower connecting rod joint and the crank pin bearing housing are fixedly connected as an integral connecting rod-crank pin structure. The key feature is that a connecting rod balance box is connected to the lower connecting rod joint or the crank pin bearing housing, forming the connecting rod balancing structure of the beam pumping unit. The connecting rod balance box is connected to the lower connecting rod joint or the crank pin bearing housing via a flange or pin. This utility model achieves a new balancing method by setting a balance box at the lower end of the connecting rod or the crank pin bearing housing. The counterweight is set at the lower end of the connecting rod or the crank pin bearing housing, reducing the force on the crank pin and lowering the risk of crank pin breakage. It also avoids the drawback of large inertial loads in beam balancing.

Description

Technical Field

[0001] This utility model belongs to the field of oilfield crude oil extraction technology, and in particular relates to a connecting rod balancing mechanism for a beam pumping unit. Background Technology

[0002] Beam pumping units are the most important equipment for crude oil extraction in oil fields. There are currently four main balancing methods for beam pumping units: beam balancing, crank balancing, combined balancing, and pneumatic balancing. The first three are mechanical balancing methods and are the most mainstream. 1. Beam balancing: A counterweight is installed at the tail of the beam to balance the load on the headstock. Its advantages are that it directly balances the load on the polished rod, resulting in less stress on the tail shaft, connecting rod, and crank pin, and easy adjustment. Disadvantages are that the tail shaft and connecting rod assembly are subjected to alternating tensile and compressive loads, making them prone to fatigue. Furthermore, the dynamic load of the counterweight is relatively large, so the operating speed cannot be high, and the counterweight cannot be too heavy. Otherwise, if the polished rod breaks, the counterweight will fall almost freely, and the huge impact will cause serious damage to the pumping unit. This limits its use in deep wells with high loads. 2. Crank balancing: The counterweight is located on the crank of the reducer, which is an indirect balancing method. Its advantages are lower dynamic load, better impact resistance, and suitability for deep wells with high loads. The disadvantages are that the connecting rod and crank pin are subjected to great stress, and once the crank pin fatigues and breaks, it will cause serious damage to the entire machine. Adjusting the balance requires moving the crank counterweight, which is cumbersome and poses a significant safety risk due to its weight. 3. Compound balancing: This method distributes the counterweight between the walking beam and the crank, combining the advantages of both and mitigating their disadvantages to some extent. However, the crank pin is still subjected to significant stress, and crank pin breakage remains a major cause of serious damage. Adjusting the balance is also inconvenient.

[0003] Beam pumping units are characterized by operating in the field, under heavy loads, and running continuously 24 hours a day. A malfunction can lead to well shutdown and high repair costs. Among the failures causing serious damage to pumping units, crankpin fatigue fracture accounts for a significant proportion, approximately 30-40%. Therefore, reducing the stress on the crankpin and increasing its reliability are crucial ways to reduce the failure rate. Optimizing the stress on the crankpin through balancing methods can reduce the probability of crankpin fracture. Utility Model Content

[0004] The purpose of this utility model is to overcome the shortcomings of the above-mentioned technology and provide a connecting rod balancing mechanism for a beam pumping unit. A connecting rod balancing box is installed at the lower end of the connecting rod of the beam pumping unit. The gravity of the connecting rod balancing box acts directly on the connecting rod, thereby reducing the force on the crank pin, optimizing the stress state of the crank pin, and reducing the inertial load of the whole machine.

[0005] To achieve the above objectives, this utility model adopts the following technical solution: a connecting rod balancing mechanism for a beam pumping unit, comprising a lower connecting rod joint, a crank pin bearing seat, a crank pin, a crank, a crank pin bearing cover, and a crank pin bearing. The lower connecting rod joint and the crank pin bearing seat are fixedly connected to an integral connecting rod-crank pin structure. A connecting rod balancing box is connected to the lower connecting rod joint or the crank pin bearing seat, forming the connecting rod balancing structure of the beam pumping unit. The connecting rod balancing box is connected to the lower connecting rod joint or the crank pin bearing seat via a flange or a pin.

[0006] Furthermore, the connecting rod balance box is a box that holds several small balance blocks, forming a balance balance box that facilitates the adjustment of the overall weight by placing and removing the small balance blocks.

[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 fitted onto the outer side 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, the top of the connecting rod balance box is provided with a parallel ear plate, and the parallel ear plate is provided with a connecting pin hole. The parallel ear plate is pinned to the bridge flange. The bridge flange is fastened to the lower connecting rod 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. The lower side of the bridge flange is provided with a lug, and the lug is provided with a hinge pin hole. The parallel ear plate on the top of the balance counterweight box is inserted into the bridge flange and pinned by a cylindrical pin, forming an eccentric pin connection structure between the connecting rod crank pin structure and the balance counterweight box.

[0009] Furthermore, the top of the connecting rod balance box is provided with a parallel ear plate, which is connected to a double-layer hinge mechanism. The double-layer hinge mechanism includes a balance box bearing, a bearing housing, a balance box connecting plate, an inner bearing cover, an outer bearing cover, and a crank pin bearing cover. The crank pin bearing cover is shaped like a circular stepped platform and is fixedly connected to the crank pin bearing housing. The inner ring of the balance box bearing is connected to the stepped platform of the crank pin bearing 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 cover presses against the outer ring of the balance box bearing and is fixedly connected to the balance box connecting plate. The inner bearing cover presses against the inner ring of the balance box bearing and is fixedly connected to the crank pin bearing cover. The balance box connecting plate is bolted to the parallel ear plate at the top of the connecting rod balance box, forming a concentric pin connection structure between the connecting rod balance box and the connecting rod crank pin structure.

[0010] Beneficial Effects: Compared with existing technologies, this invention features a balance box installed at the lower end of the connecting rod or on the crank pin bearing seat, creating a new balancing mechanism. This novel connecting rod balancing mechanism achieves the goals of lower dynamic load and simpler, more convenient balancing adjustment in pumping units. Furthermore, by scientifically allocating the proportions of walking beam balancing, crank balancing, and connecting rod balancing, optimal overall performance can be obtained, reducing the overall dynamic load inertia and significantly decreasing the stress on the crank pin. It offers advantages such as good energy saving, high reliability, low cost, and simple installation and adjustment. The counterweight is located at the lower end of the connecting rod, reducing the stress on the crank pin and lowering the risk of crank pin breakage. It also avoids the drawback of high inertial load from the walking beam counterweight. This invention can be used in the design of new pumping units as well as for the retrofitting of existing models. For different well conditions, connecting rod balancing can be applied alone or in any combination with walking beam balancing and crank balancing to achieve the most beneficial effect for the overall unit operation. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the connecting rod balancing structure of this utility model;

[0012] Figure 2 This is a schematic diagram of the fixed connection between the connecting rod crank pin structure and the balance counterweight box in Embodiment 1;

[0013] Figure 3 yes Figure 2 The right view;

[0014] Figure 4 This is a schematic diagram of the eccentric pin connection between the connecting rod crank pin structure and the balance counterweight box in Embodiment 2;

[0015] Figure 5 yes Figure 4 The right view;

[0016] Figure 6 This is a schematic diagram of the concentric pin connection structure of the connecting rod crank pin structure and the balance counterweight box in Embodiment 3.

[0017] Figure 7 yes Figure 6 The right view;

[0018] Figure 8 This is a partial structural diagram of the connecting rod crank pin assembly;

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

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

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

[0022] Figure 12 The curves show a comparison of the calculated forces on the crank pin with and without a connecting rod balance weight after the crank rotates 5°.

[0023] Figure 13 This is a simplified diagram of a four-bar linkage;

[0024] Figure 14 The curves are comparisons of the calculated angular accelerations of the connecting rod and walking beam after the crank rotates by 5°.

[0025] Figure 15 These are the inertial load curves of the walking beam counterweight and the connecting rod counterweight.

[0026] In the diagram: 1. Connecting rod; 1-1. Lower connector of connecting rod; 1-2. Lower connector flange of connecting rod; 2. Crank pin bearing housing; 3. Crank pin; 4. Crank; 5. Crank pin bearing cap; 6. Crank pin bearing; 7. Connecting rod balance box; 7-1. Balance box flange; 8. Oil beam; 9. Donkey head; 10. Bracket; 11. Overpass flange; 12. Cylindrical pin; 14. Connecting bearing; 15. Bearing housing; 16. Balance box connecting plate; 17. Inner bearing cover; 18. Outer bearing cover. Detailed Implementation

[0027] To better understand the above-mentioned objectives, features, and advantages of this utility model, the present utility model will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. Many specific details are set forth in the following description to provide a thorough understanding of this utility model; the described embodiments are merely some, not all, of the embodiments of this utility model. All other embodiments obtained by those skilled in the art based on the embodiments of this utility model without inventive effort are within the scope of protection of this utility model. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this utility model pertains. The terminology used in this specification of the utility model is for the purpose of describing particular embodiments only and is not intended to limit the utility model.

[0028] In the various embodiments of this utility model, 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 can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "below," "left," and "right" are used only to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship also changes accordingly.

[0029] See appendix for details Figure 1This embodiment provides a balancing mechanism for a 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 cover 5, and a crank pin bearing 6. The lower connector of the connecting rod is fixedly connected to the crank pin bearing seat as an integral connecting rod and crank pin structure. A connecting rod balance box 7 is connected to the lower connector 1-1 or the crank pin bearing seat 2, forming the connecting rod balancing structure of the beam pumping unit. The connecting rod balance box is connected to the lower connector of the connecting rod or the crank pin bearing seat through a flange or a pin.

[0030] In a preferred embodiment, the connecting rod balance box is a box that holds several small balance blocks, forming a balance balance box that allows for easy adjustment of the overall weight by placing and removing the small balance blocks.

[0031] like Figure 8 As shown, the connecting rod crank pin assembly structure includes a connecting rod lower connector 1-1, a crank pin bearing housing 2, a crank pin 3, a crank 4, a crank pin bearing cap 5, and a crank pin bearing 6. The crank pin bearing housing has an outer conical surface, with a flange at the large end of the conical surface. The flange has a threaded hole corresponding to the through hole of the connecting rod lower connector flange. The crank pin bearing is fixedly connected to the crank pin, and the crank pin is fixedly connected to the crank thread through its outer conical surface. The connecting rod lower connector is a special flange with an inner hole that mates with the outer conical surface of the crank pin bearing housing. Concentric through holes corresponding to the threaded holes of the crank pin bearing housing flange are arranged around the inner hole. During installation, bolts are used to press and fix the inner conical hole of the lower connector flange to the outer conical surface of the crank pin bearing housing, thus achieving a hinged connection between the connecting rod lower connector and the crank pin to form an integral connecting rod crank pin structure. The connecting rod crank pin structure is existing technology and will not be described in detail further. The key point of this utility model is the connection between the connecting rod balance box and the connecting rod crank pin structure, specifically, the connecting rod balance box is connected to the lower connector 1-1 of the connecting rod crank pin structure, or the connecting rod balance box is connected to the crank pin bearing. Since the lower connector and the crank pin bearing seat are fixedly connected and assembled to form the aforementioned connecting rod crank pin structure, the balance weight box is equivalent whether it is fixedly connected to the lower connector or the crank pin bearing seat. It should be noted that the connecting rod balance box is not connected to the crank.

[0032] Example 1

[0033] See appendix 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 fitted onto the outer side 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.

[0034] Example 2

[0035] See appendix for details Figure 4-5 The top of the connecting rod balance box is provided with a parallel ear plate, and the parallel ear plate is provided with a connecting pin hole. The parallel ear plate is pinned to the bridge flange 11. The bridge flange is fastened to the lower connecting rod 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. The lower side of the bridge flange is provided with a lug, and the lug is provided with a hinge pin hole. The parallel ear plate on the top of the balance counterweight box is inserted into the bridge flange and pinned by a cylindrical pin 12, forming an eccentric pin connection structure between the connecting rod crank pin structure and the balance counterweight box.

[0036] Example 3

[0037] See appendix for details Figure 6-7 In a preferred embodiment, the connecting rod balance box is provided with a parallel ear plate 7-2 at its top. The parallel ear plate is connected to a double-layer hinge mechanism. The double-layer hinge mechanism includes a balance box bearing 14, a bearing seat 15, a balance box connecting plate 16, an inner bearing cover 17, an outer bearing cover 18, and a crank pin bearing cover 5. The crank pin bearing cover is in the shape of a circular stepped platform and is fixedly connected to the crank pin bearing seat. The inner ring of the balance box bearing is connected to the stepped platform of the crank pin bearing cover. The outer ring of the balance box bearing is connected to the inner circular groove of the balance box connecting plate. The outer bearing cover presses against the outer ring of the balance box bearing and is fixedly connected to the balance box connecting plate. The inner bearing cover presses against the inner ring of the balance box bearing and is fixedly connected to the crank pin bearing cover. The balance box connecting plate is bolted to the parallel ear plate at the top of the connecting rod balance box, forming a concentric pin connection structure between the connecting rod balance box and the connecting rod crank pin structure.

[0038] Design principle of link balance

[0039] The core of linkage balancing technology is installing a counterweight box at the lower end of the linkage. There are three main ways to connect the linkage balance box:

[0040] Direct fixed connection: The counterweight box is directly fixed to the lower connector of the connecting rod or the crank pin bearing seat. This method of counterweight box exerts an additional bending moment on the connecting rod and is suitable for working conditions where the weight of the counterweight box is not too large.

[0041] Eccentric hinge: The counterweight box is hinged to a connecting plate, which is fixedly connected to the lower joint of the connecting rod or the crank pin bearing seat. This method of counterweight box generates a very small additional bending moment on the connecting rod and is suitable for most working conditions.

[0042] Concentric hinge: The counterweight box is hinged to the lower joint of the connecting rod or the crank pin bearing seat, with the hinge center concentric with the crank pin axis. This method of counterweight box does not generate additional bending moment on the connecting rod and is suitable for large counterweight box applications.

[0043] The calculation data for reducing the overall vehicle's inertial load according to this invention are as follows:

[0044] This invention achieves optimal overall performance by evenly distributing the balance between the walking beam, crank, and connecting rod, reducing the overall inertial load and significantly decreasing the stress on the crankpin. This is further illustrated by mechanical calculations.

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

[0046] The tension on the connecting rod generated by the crank counterweight is transmitted to the connecting rod through the crank pin. However, with connecting rod balancing (i.e., a counterweight is placed at the lower end of the connecting rod), a portion of the connecting rod tension is directly provided by the counterweight, bypassing the crank pin transmission. Therefore, for the same balancing effect, connecting rod balancing reduces the stress on the crank pin compared to crank balancing. In principle, if crank balancing is removed, the crank pin only transmits the tension generated by the reducer's net torque on the connecting rod, resulting in a much smaller stress on the crank pin. In practical design, since crank balancing can achieve a larger balancing torque with a smaller weight by adjusting the position of the counterweights, partial crank balancing can be retained to keep the connecting rod balance box relatively small and facilitate space arrangement.

[0047] Since connecting rod balancing does not change the parameters of a four-bar linkage, it can be assumed that the crank balancing effect is the same. This means that the tension P of the connecting rod on the walking beam is the same. L constant.

[0048] See appendix for details Figure 9 Taking the connecting rod as the object of study, its self-weight is negligible. Before adding the connecting rod balance box, the connecting rod is a two-force member hinged at both ends, with the tail shaft and crank pin exerting tension forces on each end respectively. The two forces are equal in magnitude and opposite in direction, so the crank pin experiences a force F. 销 for:

[0049] F 销 =P L ,

[0050] Where: P L This is the tension force exerted by the tail shaft on the connecting rod.

[0051] After adding a counterweight to the lower end of the connecting rod, the force analysis is as follows: Figure 10 As shown, assume its gravity is Q. 连 The distance from the point of force to the crank pin is L. P The angle between the connecting rod and the plumb line is α. 连 ,

[0052] Taking the moment about the crankpin, the connecting rod counterweight creates an additional bending moment M on the connecting rod. 附 The normal force P from the tail axis Lt To achieve balance:

[0053] Q 连 .L P .sinα连 =P Lt L

[0054] Because of L P Much smaller than the link length L, α 连 The angle is generally no more than 17°, so if the connecting rod balance box is not heavy, the additional bending moment can be ignored. At this point, the crank pin experiences a force F. 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 be improved by making the hinge point between the balance box and the lower end of the connecting rod concentric with the crank pin, i.e., Lp=0, which completely eliminates the additional bending moment of the balance box on the connecting rod.)

[0057] As can be seen from the above calculations, the connecting rod balancing technology can significantly reduce the stress on the crank pin.

[0058] Example

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

[0060] Comparison curves as follows Figure 12 As shown, the forces on the crank pin with and without connecting rod balance weights were calculated for every 5° of crank rotation. It can be seen that the connecting rod balance weight can significantly reduce the forces on the crank pin, by an average of about 20kN, a reduction of 10.4%, thereby reducing the risk of crank pin breakage and extending the service life of the crank pin.

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

[0062] Balance is achieved by adding a counterweight to the tail of the walking beam. Because the walking beam has a large swing amplitude and reciprocates, the angular acceleration changes significantly, resulting in a large inertial load on the crank counterweight. In contrast, connecting rod balance, achieving the same balancing effect, has a smaller swing amplitude, with the larger amplitude occurring at the bottom. This results in a smaller dynamic load and a lower center of gravity, which is beneficial for the stable operation of the entire machine. The following calculations illustrate this.

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

[0064] We use the vector method for calculation. The four links—crank, connecting rod, walking beam rear arm, and base rod R, P, C, K—can be represented as follows: , , , For ease of analysis, the positive directions of each angle in the diagram 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 member are all calculated from the base member OO1, and are positive values ​​in the counterclockwise direction.

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

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

[0069] The geometric relationships in the diagram are as follows:

[0070]

[0071] θ2=2π-θ+α

[0072]

[0073]

[0074]

[0075]

[0076]

[0077]

[0078] In the diagram, the relationships between the vectors are as follows:

[0079] + = +

[0080] This can be represented using a complex vector as:

[0081]

[0082] (Because the angle between K and the base rod OO1 is a fixed value of 0, there is no coefficient.)

[0083] Differentiate both sides of the above equation with respect to time:

[0084]

[0085] According to Euler's formula The above formula can be rewritten as:

[0086]

[0087] Setting the real and imaginary parts of both sides equal, we obtain the system of equations:

[0088]

[0089]

[0090] By solving the simultaneous equations and taking the derivative, the angular velocities of the connecting rod and the walking beam can be obtained. , for

[0091]

[0092]

[0093] Differentiating the above two equations with respect to time yields the angular accelerations of the connecting rod and the traveling beam. and

[0094]

[0095]

[0096] In the formula, ,

[0097] Since the crank rotates at a basically uniform speed, ,but and for:

[0098]

[0099]

[0100] The velocity of the center of gravity, Vmove, and the acceleration, amove, of the balance weight on the walking beam can be calculated using the following formulas:

[0101]

[0102]

[0103] The velocity VQ of the center of gravity of the connecting rod counterweight can be calculated by the following formula:

[0104] The magnitude of the velocity at point A, at the crank pin of the connecting rod, is ωR, and its direction is perpendicular to the crank. According to the four-bar linkage parameter diagram and the laws of rigid body planar motion, the velocity components along the connecting rod direction at points A, B, and Q are equal, which can be expressed as:

[0105]

[0106] Similarly, the velocity component of point A perpendicular to the connecting rod direction is:

[0107]

[0108] The velocity component at point B perpendicular to the connecting rod is:

[0109]

[0110] Based on the planar motion of a rigid body, the velocity component of point Q in the direction perpendicular to the link can be obtained as follows:

[0111]

[0112] Clearly, the absolute velocity value V at point Q Q for:

[0113]

[0114] The acceleration at the center of gravity Q of the connecting rod's counterweight can be decomposed into the acceleration in the direction of the connecting rod and the acceleration perpendicular to the connecting rod, which can be respectively decomposed into the acceleration V. QP and V QT Find the derivative, and then calculate its absolute acceleration a. Q for:

[0115]

[0116] Third, calculations show that if the same balancing effect as the walking beam balancing is achieved by using connecting rod balancing, that is, comparing the inertial loads of the two with the condition that the moments about the central axis are equal, the inertial load of connecting rod balancing is much smaller than that of walking beam balancing.

[0117] Substituting the above static analysis data into the design example of a pumping unit CYJ12-6-73HF, we find R=1510mm, A=5500mm, C=2930mm, P=5840mm, H=5702mm, I=3065mm, and Lp=300mm. Assuming the walking beam counterweight is 20kN, and designing the connecting rod counterweight with equal moments about the central axis, we arrive at 27.3kN.

[0118] See appendix for details Figure 14By calculating the angular acceleration of the connecting rod and the walking beam for every 5° rotation of the crank, a comparison curve can be obtained.

[0119] Calculation results show that the maximum angular acceleration of the connecting rod is 0.04 m / s². 2 Only the maximum angular acceleration of the walking beam is 0.13 m / s². 2 One-third.

[0120] Further calculations are performed on the center of gravity accelerations of the walking beam counterweight and the connecting rod counterweight. Based on the acceleration formula, the inertial load curves of the walking beam counterweight and the connecting rod counterweight can be calculated, for example... Figure 15 :

[0121] The calculation results show that, to achieve the same balancing effect, the maximum inertial load of the connecting rod balance weight is only 0.04 kN, while the maximum inertial load of the walking beam balance weight is 1.07 kN. The inertial load of the connecting rod balance weight is negligible compared to that of the walking beam balance weight.

[0122] Because the counterweight is located at the lower end of the connecting rod, it functions similarly to a walking beam counterweight, directly balancing the load on the bare rod. This reduces the stress on the crank pin, lowering the risk of crank pin breakage, while also avoiding the drawback of large inertial loads inherent in walking beam counterweights. For ease of manufacturing and installation, the counterweight at the lower end of the connecting rod is designed as a box structure with internal counterweight blocks connected to the lower end of the connecting rod, simplifying overall manufacturing, installation, and balance adjustments.

[0123] The above detailed description of the connecting rod balancing mechanism of a beam pumping unit with reference to the embodiments is illustrative rather than limiting. Several embodiments can be listed according to the defined scope. Therefore, changes and modifications without departing from the overall concept of this utility model should be within the protection scope of this utility model.

Claims

1. A connecting rod balancing mechanism for a beam pumping unit, comprising a lower connecting rod joint, a crank pin bearing housing, a crank pin, a crank, a crank pin bearing cap, and a crank pin bearing, wherein the lower connecting rod joint is fixedly connected to the crank pin bearing housing as an integral connecting rod-crank pin structure, characterized in that: A connecting rod balance box is connected to the lower connector of the connecting rod or the crank pin bearing seat, forming the connecting rod balance structure of the walking beam pumping unit. The connecting rod balance box is connected to the lower connector of the connecting rod or the crank pin bearing seat through a flange or a pin.

2. The beam-pumping unit connecting-rod balancing mechanism according to claim 1, characterised in that: The connecting rod balance box is a box that holds several small balance blocks, forming a balance balance box that allows for easy adjustment of the overall weight by placing and removing the small balance blocks.

3. The beam-pumping unit connecting-rod balancing mechanism according to claim 1 or 2, characterised 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 fitted onto the outer side 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 beam-pumping unit connecting-rod balancing mechanism according to claim 1 or 2, characterised in that: The top of the connecting rod balance box is provided with a parallel ear plate, and the parallel ear plate is provided with a connecting pin hole. The lower end of the connecting rod lower joint flange is provided with a lug, and the lug is provided with a hinge pin hole. The parallel ear plate is inserted into the connecting rod lower joint flange and is pinned 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 beam-pumping unit connecting-rod balancing mechanism according to claim 1 or 2, characterised in that: The top of the connecting rod balance box is provided with a parallel lug plate, which is connected to a double-layer hinge mechanism. The double-layer hinge mechanism includes a balance box bearing, a bearing housing, a balance box connecting plate, an inner bearing cover, an outer bearing cover, and a crank pin bearing cover. The crank pin bearing cover is shaped like a circular stepped platform and is fixedly connected to the crank pin bearing housing. The inner ring of the balance box bearing is connected to the stepped platform of the crank pin bearing 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 cover presses against the outer ring of the balance box bearing and is fixedly connected to the balance box connecting plate. The inner bearing cover presses against the inner ring of the balance box bearing and is fixedly connected to the crank pin bearing cover. The balance box connecting plate is bolted to the parallel lug plate at the top of the connecting rod balance box, forming a concentric pin connection structure between the connecting rod balance box and the connecting rod crank pin structure.

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