A walking beam pumping unit crank pin bearing fault diagnosis method

Abstract

The present application belongs to the technical field of fault detection of beam pumping unit, and particularly relates to a beam pumping unit crank pin bearing fault diagnosis method. The method comprises: obtaining the horse head displacement curve and the indicator diagram of the beam pumping unit, and determining the crank pin bearing fault of the pumping unit when the horse head displacement curve and the indicator diagram in a certain stroke satisfy any of the following conditions: burrs appear in the corresponding points of the first half of the horse head displacement curve in the horse head upward process, and the loading line in the indicator diagram is twisted; burrs appear in the corresponding points of the first half of the horse head displacement curve in the downward process of the horse head, and the unloading line in the indicator diagram is twisted; burrs appear in the corresponding points of the first half in the upward process of the horse head and in the corresponding points of the first half in the downward process of the horse head, and the loading line and the unloading line in the indicator diagram are twisted. The method does not need to be inspected by a person on the site, can simply, quickly and timely find the crank pin bearing fault of the pumping unit, and ensures the normal operation of the pumping unit.

Description

Technical Field

[0001] This invention belongs to the field of fault detection technology for beam pumping units, specifically relating to a fault diagnosis method for crank pin bearings in beam pumping units. Background Technology

[0002] my country has over 200,000 pumping units of various types, with beam pumping units accounting for more than 90% of the total in operation in oilfields. Pumping units include both surface and downhole equipment. While remote diagnostic methods based on dynamometer card changes can be used to diagnose the operating conditions of downhole equipment, this method is not currently applied to surface equipment fault diagnosis. In field operation, beam pumping units frequently experience vibrations, shaking, abnormal noises, and even overturning due to the susceptibility of crank pins (in surface equipment) to failure. Failure to detect and address these issues promptly during inspections can negatively impact the stable operation of oil and gas production. Currently, surface equipment inspections primarily rely on manual on-site inspections, video inspections, and drone inspections. These methods all suffer from varying degrees of high cost, low efficiency, and delayed fault detection, affecting the safe operation of pumping units and consequently the normal operation of oil and gas production. Summary of the Invention

[0003] The purpose of this invention is to provide a method for diagnosing crank pin bearing faults in a beam pumping unit, in order to solve the technical problems of high cost and low efficiency of on-site inspections and the inability to detect crank pin bearing faults in pumping units in a timely manner.

[0004] To solve the above-mentioned technical problems, the present invention provides a method for diagnosing crank pin bearing faults in a beam pumping unit, the method comprising:

[0005] Obtain the displacement curve and indicator diagram of the walking beam pumping unit. If the displacement curve and indicator diagram of the walking beam pumping unit within a certain stroke meet any of the following conditions, the crank pin bearing of the pumping unit is determined to be faulty:

[0006] The donkey head displacement curve shows burrs at corresponding points in the first half of the upward movement of the donkey head, and the loading line in the indicator diagram shows twisting.

[0007] The donkey head displacement curve shows burrs at corresponding points in the first half of the donkey head's descent process, and the load reduction line in the indicator diagram shows twisting.

[0008] The donkey head displacement curve shows burrs at the corresponding points in the first half of the upward movement and the first half of the downward movement, and the loading and unloading lines in the indicator diagram are twisted.

[0009] The term "torsion" refers to the displacement change trend of points exceeding a set number that is opposite to the normal change trend, and the deviation of the load value of these points from the corresponding load value in the normal indicator diagram is greater than the set tort threshold of the indicator diagram.

[0010] Furthermore, when the absolute value of the difference between the displacement of a certain point in the first half of the donkey head displacement curve during the upward movement of the donkey head and the average displacement of the two adjacent points, and the ratio of the total displacement of the donkey head in one stroke to the set displacement burr degree threshold, it is determined that a burr has appeared in the corresponding point in the first half of the upward movement of the donkey head displacement curve.

[0011] Furthermore, when the absolute value of the difference between the displacement of a certain point in the first half of the donkey head displacement curve and the average displacement of the two adjacent points during the downward movement of the donkey head is greater than or equal to the ratio of the total displacement of the donkey head in one stroke to the set displacement burr degree threshold, it is determined that a burr has appeared in the corresponding point in the first half of the downward movement of the donkey head displacement curve.

[0012] Furthermore, the normal indicator diagram is the indicator diagram or theoretical indicator diagram when the pumping unit is not malfunctioning.

[0013] Furthermore, an alarm will be triggered when the donkey head displacement decreases or remains unchanged during the upward phase of the donkey head displacement curve.

[0014] Furthermore, an alarm is triggered when the displacement of the pumping unit's pumping head increases or remains unchanged during the downward phase of the pumping head displacement curve.

[0015] Furthermore, when the maximum value of the donkey head load curve in this stroke is greater than the maximum value of the load curve in the previous stroke, and the degree of the greater value is greater than or equal to the first set threshold, an alarm is triggered.

[0016] Furthermore, when the maximum value of the donkey head load curve of the stroke is greater than the maximum value of the load curve within a set time period before the stroke, and the degree of the greater value is greater than or equal to the second set threshold, an alarm is triggered.

[0017] This invention is a pioneering invention, and its beneficial effects are as follows: This invention applies the method originally used for downhole equipment diagnosis to the fault diagnosis of surface equipment. Through research, it was found that when the crank pin bearing of the pumping unit fails, the displacement curve of the pumping unit and the indicator diagram will show corresponding changes. When the crank pin bearing of the pumping unit has faults such as ball or raceway peeling, cracks or corrosion, it will cause wear on the shaft or bearing seat, resulting in changes in the length of the connecting rod and the length of the crank. Because the crank pin bearing, in addition to rotating at low speed, also revolves around the output shaft of the gearbox, after the crank pin bearing is damaged, the ball bearing failure point rotates circumferentially within the bearing cavity due to gravity. Theoretically, the fault symptoms can appear at any point. However, the force transmitted from the connecting rod to the crank pin shaft is tensile stress during the upstroke and compressive stress during the downstroke. Therefore, early fault symptoms appear more often after the crank has rotated to the highest or lowest position of the crank head. At the moment of reversing unloading or reversing loading, ball jamming and misalignment will cause the crank to exhibit short-term non-uniform rotation characteristics. This is reflected in the displacement curve as burrs appearing after the crank has rotated to the highest or lowest position of the crank head, and the corresponding loading or unloading lines in the indicator diagram will show twisting. Based on this, the present invention determines the crank pin bearing failure of the pumping unit through the following three situations: 1) burrs appear at corresponding points in the first half of the upward movement of the donkey head displacement curve, and the loading line in the indicator diagram shows twisting; 2) burrs appear at corresponding points in the first half of the downward movement of the donkey head displacement curve, and the unloading line in the indicator diagram shows twisting; 3) burrs appear at corresponding points in both the first half of the upward and downward movement of the donkey head displacement curve, and the loading and unloading lines in the indicator diagram show twisting. Furthermore, the present invention determines twisting when the displacement change trend at points exceeding a set number is opposite to the normal trend, and the deviation of the load value at these points from the corresponding load value in the normal indicator diagram is greater than the set twisting threshold. Based on this discovery, the present invention proposes a method for diagnosing the crank pin bearing of the pumping unit using the donkey head displacement curve and indicator diagram. This eliminates the need for on-site inspections and allows for simple, quick, and timely detection of crank pin bearing failures in the pumping unit, ensuring its normal operation. Attached Figure Description

[0018] Figure 1 This is an equivalent model diagram of a beam pumping unit according to an embodiment of the present invention;

[0019] Figure 2 This is a theoretical donkey head displacement curve diagram of an embodiment of the method of the present invention;

[0020] Figure 3 This is a theoretical donkey head load curve diagram of an embodiment of the method of the present invention;

[0021] Figure 4 This is a theoretical indicator diagram of the oil pumping unit according to an embodiment of the method of the present invention;

[0022] Figure 5 These are the donkey head displacement curve and donkey head load curve diagrams for the first pumping unit crank pin bearing failure in the method embodiment of the present invention.

[0023] Figure 6 This is the indicator diagram of the first oil pump crank pin bearing failure in the method embodiment of the present invention;

[0024] Figure 7 This is a diagram showing the displacement curve and load curve of the donkey head when the crank pin bearing of the second pumping unit fails, according to a method embodiment of the present invention.

[0025] Figure 8 This is a diagram illustrating the dynamometer function of the second pumping unit crank pin bearing failure according to a method embodiment of the present invention.

[0026] Figure 9 This is a flowchart of a method for diagnosing crank pin bearing faults in a beam pumping unit according to an embodiment of the present invention. Detailed Implementation

[0027] This invention applies methods originally used for downhole equipment diagnosis to fault diagnosis of surface equipment. Research reveals that when the crankpin bearing of a pumping unit fails, the displacement curve and indicator diagram show corresponding changes. When the crankpin bearing of the pumping unit experiences problems such as ball or raceway spalling, cracks, or corrosion, it causes wear on the shaft or bearing housing. Figure 1As shown, this causes changes in the lengths of the connecting rod BC and the crank AB. Since the crank pin bearing, in addition to its low-speed rotation, also revolves around the gearbox output shaft, after the crank pin bearing fails, due to gravity, the ball bearing failure point rotates circumferentially within the bearing cavity. Theoretically, the fault symptoms can appear at any point. However, the force transmitted from the connecting rod to the crank pin shaft is tensile stress during the upstroke and compressive stress during the downstroke. Therefore, early fault symptoms are more likely to appear after the crank rotates to B1 (the highest point of the crank head) or B2 (the lowest point of the crank head). At the moment of reversing unloading or reversing loading, ball jamming and misalignment will cause short-term non-uniform rotation of the crank. This manifests as burrs on the displacement curve after the crank rotates to the highest or lowest point of the crank head, and twisting of the loading or unloading lines on the corresponding indicator diagram. Based on this, the present invention determines the crank pin bearing failure of the pumping unit through the following three situations: 1) burrs appear at corresponding points in the first half of the upward movement of the donkey head displacement curve, and the loading line in the indicator diagram shows twisting; 2) burrs appear at corresponding points in the first half of the downward movement of the donkey head displacement curve, and the unloading line in the indicator diagram shows twisting; 3) burrs appear at corresponding points in both the first half of the upward and downward movement of the donkey head displacement curve, and the loading and unloading lines in the indicator diagram show twisting. Furthermore, the present invention determines twisting when the displacement change trend at points exceeding a set number is opposite to the normal trend, and the deviation of the load value at these points from the corresponding point load value in the normal indicator diagram is greater than the set indicator diagram twisting threshold. Based on this discovery, the present invention proposes a method for diagnosing the crank pin bearing of the pumping unit using the donkey head displacement curve and indicator diagram. This eliminates the need for on-site inspections by maintenance personnel, enabling simple, quick, and timely detection of crank pin bearing failures in the pumping unit, ensuring its normal operation.

[0028] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0029] Method Implementation Examples:

[0030] The beam pumping unit is a type of four-bar pumping unit, and its equivalent model is as follows: Figure 1 As shown, AB is the crank of the pumping unit, with AB2 as the crank's rotation angle 0. The crank rotates counterclockwise with an angular velocity ω. The movement of point B on the crank varies with time t and the crank's rotation angle, exhibiting a sinusoidal characteristic. B1 and B2 in the figure represent different positions of point B.

[0031] The method for detecting crank pin bearing failure in an oil pumping unit according to the present invention, such as... Figure 9 As shown, it includes the following steps:

[0032] Step 1: Obtain the displacement curve, load curve, and indicator diagram of the pumping unit for one stroke.

[0033] Sensors mounted on the walking beam of the pumping unit acquire the pumping unit head displacement curve as a function of crank angle and the pumping unit head load curve as a function of crank angle for one stroke. A dynamometer diagram showing the relationship between head load and displacement is then derived from these two curves. One stroke consists of a top stroke and a bottom stroke; the crank pin rotates one revolution, and the crank angle changes from 0 to 2π.

[0034] As the crank angle ranges from 0 to π+α, the pumping unit's "donkey head" moves upward, and the donkey head displacement curve monotonically increases. At this point, the donkey head load equals the weight of the rod column plus the weight of the liquid column above the piston. The donkey head reaches its highest position when the crank angle is π+α. As the crank angle ranges from π+α to 2π, the pumping unit's "donkey head" moves downward, and the donkey head displacement curve monotonically decreases. The donkey head load equals the weight of the rod column, and reaches its lowest point when the crank angle is 2π (i.e., 0).

[0035] Under normal operating conditions of the pumping unit, multiple sets of data are collected within one stroke. The theoretical donkey head displacement curve obtained by plotting points is a non-standard sine curve, such as... Figure 2 As shown; the obtained theoretical load curve is a "trapezoidal line", as shown. Figure 3 As shown. The theoretical indicator diagram is obtained as follows. Figure 4 As shown, it is a parallelogram.

[0036] In this embodiment, N (256) points are taken at equal intervals within one stroke, and the displacement and load values ​​of these N points are collected synchronously. Then, the points are plotted to draw the displacement curve of the pumping unit's head, and the pumping unit's indicator diagram is obtained based on the displacement curve of the pumping unit's head and the load values ​​of the corresponding points.

[0037] This invention reveals that early failures of crank pin bearings occur because, in addition to low-speed rotation, the crank pin bearing also revolves around the output shaft of the gearbox. After the crank pin bearing fails, due to gravity, the ball bearing failure point rotates circumferentially within the bearing cavity. Theoretically, the failure symptoms can appear at any point on the indicator diagram. However, the force transmitted from the connecting rod to the crank pin shaft is tensile stress during the upstroke and compressive stress during the downstroke. Therefore, early failure symptoms are more likely to appear after the crank rotates to B1 (the highest point of the crank head) or B2 (the lowest point of the crank head). During reversing unloading or reversing loading, ball jamming and misalignment will cause short-term non-uniform rotation of the crank. The displacement curve is prone to burrs and becomes less smooth after the crank angle 0 point (the lowest point of the crank head) or π+α point (the highest point of the crank head). Obvious twisting phenomena are likely to appear on the loading line AB or unloading line CD of the indicator diagram.

[0038] Therefore, this invention can determine whether the crank pin bearing of the oil pumping unit is faulty by obtaining the displacement curve and indicator diagram of the donkey head.

[0039] Step 2: Determine whether burrs appear at the corresponding points in the first half of the donkey head displacement curve during the upward movement of the donkey head and the corresponding points in the first half of the downward movement of the donkey head.

[0040] When the crank pin bearing of an oil pump experiences problems such as ball or raceway spalling, cracks, or corrosion, it will cause wear on the shaft or bearing housing. Figure 1 As shown, this causes changes in the lengths of the connecting rod BC and the crank AB. Since the crank pin bearing, in addition to its low-speed rotation, also revolves around the gearbox output shaft, after the crank pin bearing fails, due to gravity, the ball bearing failure point rotates circumferentially within the bearing cavity. Theoretically, the fault symptoms can appear at any point. However, the force transmitted from the connecting rod to the crank pin shaft is tensile stress during the upstroke and compressive stress during the downstroke. Therefore, early fault symptoms are more likely to appear after the crank rotates to B1 (the highest point of the crank head) or B2 (the lowest point of the crank head). At the moment of reversing unloading or reversing loading, ball jamming and misalignment will cause short-term non-uniform rotation of the crank, which manifests as burrs on the displacement curve after the crank rotates to the highest or lowest point of the crank head.

[0041] When the crank pin bearing is damaged, the displacement of the donkey head will change abruptly after the donkey head moves to the lowest and highest positions. This is reflected on the curve as burrs appearing after the upper dead point (the point corresponding to the highest position of the donkey head), which is the corresponding point in the first half of the downward movement of the donkey head, or after the lower dead point (the lowest position of the donkey head), which is the corresponding point in the first half of the upward movement of the donkey head.

[0042] Specifically, in this embodiment, the method for determining whether burrs appear at the corresponding points in the first half of the donkey head displacement curve during the upward movement of the donkey head is as follows: when the absolute value of the difference between the displacement of a certain point in the first half of the upward movement of the donkey head displacement curve and the average displacement of the two adjacent points is greater than or equal to the ratio of the total displacement of the donkey head in one stroke to the set displacement burr degree threshold, it is determined that burrs appear at the corresponding points in the first half of the upward movement of the donkey head displacement curve.

[0043] In this embodiment, the method for determining whether burrs appear at the corresponding points in the first half of the donkey head displacement curve during the downward movement of the donkey head is as follows: when the absolute value of the difference between the displacement of a certain point in the first half of the downward movement of the donkey head displacement curve and the average displacement of the two adjacent points is greater than or equal to the ratio of the total displacement of the donkey head in one stroke to the set displacement burr degree threshold, it is determined that burrs appear at the corresponding points in the first half of the downward movement of the donkey head displacement curve.

[0044] The points corresponding to the first half of the donkey head displacement curve during the upward movement of the donkey head are represented as 0~(π+α) / 2 in the theoretical donkey head displacement curve, and the points corresponding to the first half of the downward movement of the donkey head are π+α~3(π+α) / 2.

[0045] In this embodiment, the threshold for displacement burr is set to 1%. When the calculated ratio exceeds this threshold, obvious burrs can be seen at the corresponding position on the donkey head displacement curve. Figure 5 , Figure 7 The figures show the displacement and load curves of the pumping unit's crankshaft bearing when both units experience crankshaft bearing failure. The green curve represents the displacement curve, with the horizontal axis representing the product of angular velocity ω and time t, and the vertical axis representing the displacement. A noticeable spike appears on the curve after the highest or lowest point, indicating a spike in the first half of the upward or downward movement of the pumping unit. The red curve is the dynamometer diagram, with the horizontal axis representing displacement and the vertical axis representing load. The gray curve is the load curve, with the horizontal axis representing the product of angular velocity ω and time t, and the vertical axis representing load. This curve shows no significant change compared to the normal load curve; therefore, the load curve is not required for diagnosis in this invention.

[0046] There are four possible outcomes for step two: no burrs appear at either the first half of the upward or downward movement of the beam pumping unit; burrs appear at both the first half of the upward and downward movement of the beam pumping unit; burrs appear only at the first half of the upward movement of the beam pumping unit; or burrs appear only at the first half of the downward movement of the beam pumping unit. If no burrs appear at either the first half of the upward or downward movement of the beam pumping unit, it can be directly determined that the crank pin bearing of the beam pumping unit is not faulty. For the remaining three scenarios where burrs appear, further fault diagnosis requires consultation with the indicator diagram.

[0047] Step 3: Determine whether there is obvious twisting at the corresponding position of the burr on the indicator diagram of the donkey head displacement curve.

[0048] When the crank pin bearing of an oil pump experiences problems such as ball or raceway spalling, cracks, or corrosion, it will cause wear on the shaft or bearing housing. Figure 1 As shown, this causes changes in the lengths of the connecting rod BC and the crank AB. Since the crank pin bearing, in addition to its low-speed rotation, also revolves around the gearbox output shaft, after the crank pin bearing fails, due to gravity, the ball bearing failure point rotates circumferentially within the bearing cavity. Theoretically, the fault symptoms can appear at any point. However, the force transmitted from the connecting rod to the crank pin shaft is tensile stress during the upstroke and compressive stress during the downstroke. Therefore, early fault symptoms are more likely to appear after the crank rotates to B1 (the highest point of the crank head) or B2 (the lowest point of the crank head). At the moment of reversing unloading or reversing loading, ball jamming and misalignment will cause short-term non-uniform rotation of the crank. This manifests as burrs on the displacement curve after the crank rotates to the highest or lowest point of the crank head, and twisting of the loading or unloading lines on the corresponding indicator diagram.

[0049] In the event of a crank pin bearing failure in a beam pumping unit, when the crank pin bearing is damaged, the displacement of the pumping head becomes abnormal while the load on the pumping head remains unchanged. Therefore, the dynamometer diagram of the pumping unit will also change, specifically manifested as a noticeable twisting phenomenon at the corresponding position on the dynamometer diagram. Thus, the specific judgment in step three is as follows:

[0050] 1. When burrs appear at corresponding points in the first half of the donkey head displacement curve during the upward movement of the donkey head, determine whether the loading line in the indicator diagram is twisted.

[0051] 2. When burrs appear at corresponding points in the first half of the donkey head displacement curve during the downward movement of the donkey head, determine whether the load shearing line in the indicator diagram is twisted.

[0052] 3. When burrs appear simultaneously at the corresponding points in the first half of the donkey head displacement curve during the upward movement of the donkey head and at the corresponding points in the first half of the downward movement of the donkey head, determine whether the loading line and unloading line in the indicator diagram twist at the same time.

[0053] In this embodiment, the method for determining whether a twist occurs at a corresponding position on the indicator diagram is as follows: if the displacement change trend of points exceeding a set number of points at the corresponding position on the indicator diagram is opposite to the normal change trend, and the deviation of the load value of these points from the load value of the corresponding point on the normal indicator diagram is greater than the set indicator diagram twist threshold, then a twist occurs at the corresponding position on the indicator diagram. Specifically, when the displacement change trend of points exceeding a set number of points on the loading line of the indicator diagram is opposite to the normal change trend, and the deviation of the load value of these points from the load value of the corresponding point on the normal indicator diagram is greater than the set indicator diagram twist threshold, then a twist occurs on the loading line; when the displacement change trend of points exceeding a set number of points on the unloading line of the indicator diagram is opposite to the normal change trend, and the deviation of the load value of these points from the load value of the corresponding point on the normal indicator diagram is greater than the set indicator diagram twist threshold, then a twist occurs on the unloading line.

[0054] Normal indicator diagram loading line ( Figure 4 The trend of displacement from A to B is that the displacement increases continuously with the increase of load, and the unloading line ( Figure 4 The trend of the change from C to D is that the displacement decreases continuously as the load decreases.

[0055] In this embodiment, the number of points is set to 3, and the threshold for the degree of distortion in the indicator diagram is set to 2%. An indicator diagram exhibiting distortion is shown below. Figure 6 , Figure 8 As shown. The normal indicator diagram is the indicator diagram or theoretical indicator diagram when the pumping unit is not malfunctioning.

[0056] In this embodiment, all set thresholds are obtained by analyzing and calculating the changes in displacement curves and indicator diagrams during abnormal conditions using statistical methods. When the corresponding threshold is exceeded, obvious abnormal changes can be seen on the curve. For example, the threshold for the degree of displacement burr is set by obtaining multiple displacement curves when the crank pin bearing of the pumping unit fails, calculating the deviation between the displacement value at the corresponding burr position and the normal displacement value, obtaining the average value of all deviations, and setting the threshold for the degree of displacement burr based on the average value.

[0057] Step 4: When all the above conditions are met, it is determined that the crank pin bearing of the oil pumping unit has failed.

[0058] This invention obtains the displacement curve and indicator diagram of the pumping unit's crankshaft bearing during one stroke. When these curves show specific changes, it determines that the crankshaft bearing of the pumping unit has malfunctioned. This eliminates the need for manual inspection, saving manpower and improving efficiency. At the same time, it can perform real-time detection, enabling timely detection of crankshaft bearing malfunctions in the pumping unit and preventing safety accidents.

[0059] In addition, the oil pumping unit crank pin bearing fault diagnosis method of the present invention also alarms when the following conditions occur:

[0060] 1. When the donkey head displacement curve shows a decrease or no change in the donkey head displacement during the upward movement of the donkey head;

[0061] 2. The donkey head displacement curve shows either an increase or no change in displacement during the downward movement of the donkey head in the pumping unit;

[0062] 3. The maximum value of the load curve of the donkey head at a certain moment is greater than the maximum value of the load curve within N strokes set before the certain moment, and the degree of the greater is greater than or equal to the first set degree threshold of 10%.

[0063] 4. The maximum value of the donkey head load curve at a certain moment is greater than the maximum value of the load curve within a set time period before that moment, and the degree of the difference is greater than or equal to the second set threshold of 10%.

[0064] If any of the above situations occur, it indicates that the pumping unit is malfunctioning and an alarm needs to be triggered. Staff should conduct inspections to ensure the normal operation of the pumping unit.

[0065] The present invention provides a method for diagnosing crank pin faults in a beam pumping unit. This method diagnoses the crank pin bearing based on changes in the pumping unit's head displacement curve and indicator diagram. A fault is identified when burrs appear on the head displacement curve after the corresponding points at the highest and / or lowest points, or when twisting occurs on the loading and / or unloading lines of the indicator diagram. This method eliminates the need for on-site inspections by maintenance personnel, offering a simple and quick diagnostic process, saving manpower, improving diagnostic efficiency, and ensuring the normal operation of the pumping unit. Furthermore, the invention proposes methods for determining whether burrs appear on the displacement curve and for determining twisting on the indicator diagram, which improves the accuracy of crank pin bearing diagnosis. It converts burrs and twisting into corresponding data features, facilitating machine and program identification. Additionally, the beam pumping unit crank pin bearing fault diagnosis method of the present invention can provide alarm prompts when abnormalities occur in the head displacement curve and head load curve, ensuring the normal operation of the pumping unit and eliminating safety hazards caused by pumping unit malfunctions.

Claims

1. A method for diagnosing crank pin bearing faults in a beam pumping unit, characterized in that, The method includes: Obtain the displacement curve and indicator diagram of the walking beam pumping unit. If the displacement curve and indicator diagram of the walking beam pumping unit within a certain stroke meet any of the following conditions, the crank pin bearing of the pumping unit is determined to be faulty: The donkey head displacement curve shows burrs at corresponding points in the first half of the upward movement of the donkey head, and the loading line in the indicator diagram shows twisting. The donkey head displacement curve shows burrs at corresponding points in the first half of the donkey head's descent process, and the load reduction line in the indicator diagram shows twisting. The donkey head displacement curve shows burrs at the corresponding points in the first half of the upward movement and the first half of the downward movement, and the loading and unloading lines in the indicator diagram are twisted. The term "torsion" refers to the displacement change trend of points exceeding a set number that is opposite to the normal change trend, and the deviation of the load value of these points from the corresponding load value in the normal indicator diagram is greater than the set tort threshold of the indicator diagram.

2. The method for diagnosing crank pin bearing faults in a beam pumping unit according to claim 1, characterized in that, When the absolute value of the difference between the displacement of a certain point in the first half of the upward movement of the donkey head displacement curve and the average displacement of the two adjacent points is greater than or equal to the ratio of the total displacement of the donkey head in one stroke to the set displacement burr degree threshold, it is determined that a burr has appeared in the corresponding point in the first half of the upward movement of the donkey head displacement curve.

3. The method for diagnosing crank pin bearing faults in a beam pumping unit according to claim 1, characterized in that, When the absolute value of the difference between the displacement of a certain point in the first half of the donkey head displacement curve and the average displacement of the two adjacent points during the downward movement of the donkey head is greater than or equal to the set displacement burr degree threshold, it is determined that a burr has appeared in the corresponding point in the first half of the downward movement of the donkey head displacement curve.

4. The method for diagnosing crank pin bearing faults in a beam pumping unit according to claim 1, characterized in that, The normal indicator diagram refers to the indicator diagram or theoretical indicator diagram when the pumping unit is not malfunctioning.

5. The method for diagnosing crank pin bearing faults in a beam pumping unit according to any one of claims 1-4, characterized in that, An alarm will be triggered when the donkey head displacement decreases or remains unchanged during the upward phase of the donkey head displacement curve.

6. The method for diagnosing crank pin bearing faults in a beam pumping unit according to any one of claims 1-4, characterized in that, An alarm will be triggered when the displacement of the pumping unit's head increases or remains unchanged during the downward phase of the head displacement curve.

7. The method for diagnosing crank pin bearing faults in a beam pumping unit according to any one of claims 1-4, characterized in that, An alarm is triggered when the maximum value of the load curve of the donkey head in the stroke is greater than the maximum value of the load curve in the previous stroke, and the degree of the excess is greater than or equal to the first set threshold.

8. The method for diagnosing crank pin bearing faults in a beam pumping unit according to any one of claims 1-4, characterized in that, An alarm is triggered when the maximum value of the donkey head load curve during the stroke is greater than the maximum value of the load curve within a set time period prior to the stroke, and the degree of the excess is greater than or equal to the second set threshold.

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