A walking beam pumping unit reduction gearbox bearing fault diagnosis method

Abstract

The present application belongs to the technical field of fault diagnosis of beam pumping unit, and particularly relates to a fault diagnosis method for the bearing of the reduction gearbox of a beam pumping unit. The method comprises the following steps: obtaining the horsehead displacement curve, the horsehead load curve and the dynamometer diagram of the pumping unit; and when the horsehead displacement curve, the horsehead load curve and the dynamometer diagram in a certain stroke simultaneously satisfy the following conditions, determining the fault of the bearing of the reduction gearbox of the pumping unit: the horsehead displacement curve has dense burrs, and the corresponding points at the highest position of the horsehead are offset from the corresponding points at the highest position of the normal horsehead displacement curve, and the degree of offset is greater than a set offset degree threshold; the deviation of the load value from the maximum load value on the horsehead load curve is less than a set load deviation threshold, the duration is less than a first set time, the deviation of the load value from the minimum load value is less than the set load deviation threshold, the duration is less than a second set time, and the horsehead load curve has dense burrs; and the dynamometer diagram of the pumping unit is an irregular polygon.

Description

Technical Field

[0001] This invention belongs to the field of fault diagnosis technology for beam pumping units, and specifically relates to a method for diagnosing bearing faults in the gearbox of a beam pumping unit. 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 changes in indicator diagrams can be used to diagnose the operating conditions of downhole equipment, this method is not currently applied to fault diagnosis of surface equipment. In field operation, beam pumping units frequently experience vibrations, shaking, abnormal noises, and even rollovers due to the susceptibility of gearbox failures. Failure to detect and address these issues promptly during inspections can negatively impact the stable operation of oil and gas production. Gearbox bearing failure is a common surface fault in beam pumping units. Currently, inspections mainly 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. When gearbox bearing failures are not detected in a timely manner, the safe operation of the pumping unit is affected, thus impacting 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 bearing faults in the gearbox of a beam pumping unit, in order to solve the technical problems of high inspection costs, low efficiency, and untimely fault detection in the gearbox bearings of beam pumping units.

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

[0005] Obtain the displacement curve, load curve, and indicator diagram of the pumping unit. If the displacement curve, load curve, and indicator diagram of the pumping unit simultaneously meet the following conditions during a certain stroke, the gearbox bearing of the pumping unit is determined to be faulty:

[0006] The donkey head displacement curve shows dense spikes, and the corresponding point of the highest point of the donkey head is offset from the corresponding point of the highest point of the donkey head in the normal donkey head displacement curve, and the degree of offset is greater than the set offset degree threshold.

[0007] The duration for which the deviation between the load value and the maximum load value on the donkey head load curve is less than the set load deviation threshold is less than the first set time, the duration for which the deviation between the load value and the minimum load value is less than the set load deviation threshold is less than the second set time, and dense spikes appear on the donkey head load curve.

[0008] The pumping unit's indicator diagram appears as an irregular polygon.

[0009] Furthermore, if the displacement deviation of N2 points out of N1 points on the donkey head displacement curve is greater than the set displacement deviation threshold, then it is determined that the donkey head displacement curve has dense burrs; the displacement deviation is the ratio of the absolute value obtained by subtracting the displacement value of the point from the average displacement of the points before and after the point to the total displacement value of the current stroke, and N1 > N2 ≥ 3.

[0010] Furthermore, the degree of deviation between the highest point of the donkey head displacement curve and the highest point of the normal donkey head displacement curve is: the deviation between the stroke time of the upper stroke of the donkey head displacement curve and the stroke time of the normal donkey head displacement curve, or the deviation between the stroke time of the lower stroke of the donkey head displacement curve and the stroke time of the normal donkey head displacement curve.

[0011] Furthermore, the deviation between the stroke time on the donkey head displacement curve and the stroke time on the normal donkey head displacement curve is calculated as follows: the absolute value of the difference between the stroke time on the donkey head displacement curve and the stroke time on the normal donkey head displacement curve is divided by the stroke time on the normal donkey head displacement curve; the deviation between the stroke time on the donkey head displacement curve and the stroke time on the normal donkey head displacement curve is calculated as follows: the absolute value of the difference between the stroke time on the donkey head displacement curve and the stroke time on the normal donkey head displacement curve is divided by the stroke time on the normal donkey head displacement curve.

[0012] Furthermore, the method for determining the presence of dense spikes in the donkey head load curve is as follows: when the load deviation of N4 points out of N3 points on the donkey head load curve is greater than the set load deviation threshold, the donkey head load curve is determined to have dense spikes; the load deviation is the ratio of the absolute value obtained by subtracting the load value of the point from the average load of the points before and after the point to the maximum load value, and N3 > N4 ≥ 3.

[0013] Furthermore, the normal donkey head displacement curve is the donkey head displacement curve when the pumping unit is not malfunctioning or the theoretical donkey head displacement curve.

[0014] 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.

[0015] 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.

[0016] 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.

[0017] 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.

[0018] This invention is a pioneering invention with the following beneficial effects: It applies the remote diagnostic technology of dynamometer charts, originally used for downhole equipment fault diagnosis, to the fault diagnosis of surface equipment. Research and analysis revealed that when the gearbox bearing of a beam pumping unit malfunctions, it causes wear on the shaft or bearing housing, leading to vibrations in the gear meshing during gearbox operation. This results in changes in the donkey head displacement, with the donkey head displacement curve exhibiting dense burrs. In severe cases, intermittent jamming and failure of the gear transmission in the gearbox occur, causing uneven upstroke and downstroke times, resulting in unstable pumping unit operation and intermittent stops. The highest point on the donkey head displacement curve shifts to the left or right, no longer in the middle of each stroke. When the gearbox bearing jams or fails, the load cannot be transmitted from the gearbox to the pumping unit's beam and donkey head, resulting in a decrease in the measured load value. When the gearbox bearing rotates back to normal, the load value suddenly increases again. Therefore, the load curve exhibits dense burrs, and the stable portion (upward and downward lines) becomes shorter. The dynamometer chart combines the abnormal changes in displacement and load, presenting them as an irregular polygon. Based on this discovery, this invention identifies typical characteristics of the donkey head displacement curve, donkey head load curve, and indicator diagram when the gearbox bearing fails. These characteristics include: dense burrs on the donkey head displacement curve; a deviation between the corresponding point at the highest point of the donkey head and the corresponding point at the highest point of the donkey head on the normal donkey head displacement curve, with the deviation exceeding a set deviation threshold; dense burrs on the donkey head load curve; and shortened or even disappeared upward and downward stabilizing lines; and the pumping unit indicator diagram appearing as an irregular polygon. These characteristics serve as the basis for judging gearbox bearing failure. When the above characteristics appear within a certain stroke of a beam pumping unit, a diagnostic method can be used to directly determine that the gearbox bearing of the pumping unit has failed. This method provides a simple, convenient, quick, and timely diagnosis of the gearbox bearing of a beam pumping unit, eliminating the need for inspection personnel to conduct on-site inspections and saving labor costs. Attached Figure Description

[0019] Figure 1 This is an equivalent model diagram of a beam pumping unit according to an embodiment of the present invention;

[0020] Figure 2 This is a theoretical donkey head displacement curve diagram of an embodiment of the method of the present invention;

[0021] Figure 3 This is a theoretical donkey head load curve diagram of an embodiment of the method of the present invention;

[0022] Figure 4 This is a theoretical indicator diagram of the oil pumping unit according to an embodiment of the method of the present invention;

[0023] Figure 5 This is a diagram showing the displacement curve and load curve of the donkey head when the bearing of the pumping unit gearbox is damaged, according to an embodiment of the method of the present invention.

[0024] Figure 6 This is another embodiment of the method of the present invention, showing the displacement curve and load curve of the donkey head when the bearing of the pumping unit gearbox is damaged;

[0025] Figure 7 This is a diagram showing the operation of an oil pump when the gearbox bearing is damaged, according to an embodiment of the present invention.

[0026] Figure 8 This is a flowchart of a method for diagnosing bearing faults in a beam pumping unit gearbox, according to an embodiment of the present invention. Detailed Implementation

[0027] This invention applies the remote diagnostic technology of dynamometer charts, originally used for fault diagnosis of downhole equipment, to fault diagnosis of surface equipment. Research and analysis revealed that when the gearbox bearing of a beam pumping unit malfunctions, it causes wear on the shaft or bearing housing, leading to vibrations in the gear meshing during gearbox operation. This results in changes in the head displacement, with the head displacement curve exhibiting dense burrs. In severe cases, intermittent jamming and failure of the gear transmission in the gearbox occur, causing uneven upstroke and downstroke times, resulting in unstable pumping unit operation and intermittent stops. The highest point on the head displacement curve shifts to the left or right, no longer in the middle of each stroke. When the gearbox bearing jams or fails, the load cannot be transmitted from the gearbox to the walking beam and head of the pumping unit, resulting in a decrease in the measured load value. When the gearbox bearing rotates back to normal, the load value suddenly increases again. Therefore, the load curve exhibits dense burrs, and the stable portion (upward and downward lines) becomes shorter. The dynamometer chart combines the abnormal changes in displacement and load, presenting them as an irregular polygon. Based on this discovery, this invention identifies typical characteristics of the donkey head displacement curve, donkey head load curve, and indicator diagram when the gearbox bearing fails. These characteristics include: dense burrs on the donkey head displacement curve; a deviation between the corresponding point at the highest point of the donkey head and the corresponding point at the highest point of the donkey head on the normal donkey head displacement curve, with the deviation exceeding a set deviation threshold; dense burrs on the donkey head load curve; and shortened or even disappeared upward and downward stabilizing lines; and the pumping unit indicator diagram appearing as an irregular polygon. These characteristics serve as the basis for judging gearbox bearing failure. When the above characteristics appear within a certain stroke of a beam pumping unit, a diagnostic method can be used to directly determine that the gearbox bearing of the pumping unit has failed. This method provides a simple, convenient, quick, and timely diagnosis of the gearbox bearing of a beam pumping unit, eliminating the need for inspection personnel to conduct on-site inspections and saving labor costs.

[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] like Figure 8 As shown, the method for diagnosing bearing faults in the gearbox of a beam pumping unit according to the present invention includes the following steps:

[0032] Step 1: Obtain the pumping unit's pumping head operation data during one stroke, and obtain the pumping head displacement curve, pumping head load curve, and indicator diagram for that stroke.

[0033] A stroke consists of a topstroke and a bottomstroke. Plot the head displacement curve as a function of crank angle (ωt) and the head load curve as a function of crank angle (ωt) for this stroke. Simultaneously, plot the indicator diagram of the head load as a function of head displacement for this stroke.

[0034] In this embodiment, N (256) points are taken at equal intervals within a stroke, and the load value and displacement value of each point are collected synchronously to draw the donkey head displacement curve and donkey head load curve of the stroke, and draw the indicator diagram based on the donkey head displacement curve and donkey head load curve.

[0035] The theoretical displacement curve of a beam pumping unit under normal operating conditions is a smooth, non-standard sine wave. At π+α, the beam head displacement curve reaches its highest point, and the beam head is also at its highest position; at 0 or 2π, the beam head displacement curve reaches its lowest point, and the beam head is at its lowest position. Figure 2 As shown.

[0036] Under theoretical conditions, when the pumping unit moves upward, the load on the pumping head mainly includes the weight of the rod and the weight of the liquid column above the piston. When the pumping unit moves downward, the load on the pumping head mainly consists of the weight of the rod in the liquid column. Theoretically, the loads on the pumping head during upward and downward movements are two horizontal lines. The transition from upward to downward and from downward to upward movements, based on the loads on the pumping head at the upward and downward suspension points, is further superimposed with the change in the elastic load of the rod, forming a trapezoidal curve, as shown below. Figure 3 As shown.

[0037] The theoretical indicator diagram only considers the static load borne by the donkey head suspension point and the elastic deformation of the pipe rod caused by the static load; the load-displacement curve is a parallelogram. For example... Figure 4 As shown.

[0038] When the gearbox bearing fails, because the gearbox bearing rotates a full circle, the rolling element failure point rotates continuously along the circumference within the bearing cavity, and jamming can occur at any time. The burrs on the crankshaft displacement curve and crankshaft load curve can occur at any phase of the crank angle without a fixed pattern, causing damage to the indication of power. Figure 4 The shapes of the edges and four points change irregularly. Through research and analysis, this invention has found that when the gearbox bearing is damaged, the donkey head displacement curve, donkey head load curve, and indicator diagram typically exhibit the following characteristics: the donkey head displacement curve shows dense burrs, and the corresponding point at the highest point of the donkey head is offset compared to the normal donkey head displacement curve; the donkey head load curve shows dense burrs, and the upward and downward load stability lines become shorter or even disappear; the pumping unit indicator diagram presents as an irregular polygon. Therefore, this invention can determine whether the gearbox bearing of the pumping unit is faulty by judging whether the above characteristics are present.

[0039] Step 2: Determine whether the donkey head displacement curve has dense spikes and whether the offset between the corresponding point of the highest point of the donkey head and the corresponding point of the highest point of the donkey head on the normal donkey head displacement curve is greater than the set offset threshold.

[0040] Gearbox bearing failure can cause vibrations in the meshing of gears during gearbox operation, resulting in changes in the donkey head displacement. The donkey head displacement curve will show dense burrs. In severe cases, the gear transmission in the gearbox will intermittently jam and fail, leading to uneven upstroke and downstroke times. This will cause the pumping unit to run unstablely and stop intermittently. The highest point on the donkey head displacement curve will shift to the left or right and will no longer be in the middle of each stroke.

[0041] In this embodiment, the method for determining whether dense burrs appear on the donkey head displacement curve is as follows: if the displacement deviation of N2 points out of N1 points on the donkey head displacement curve is greater than the set displacement deviation threshold, then the donkey head displacement curve is determined to have dense burrs; otherwise, it is determined that no dense burrs appear. The displacement deviation is the ratio of the absolute value obtained by subtracting the displacement value of the point from the average displacement of the points before and after the point to the total displacement value of the current stroke, and N1 > N2 ≥ 3.

[0042] In this embodiment, the displacement deviation threshold is set to 1%. When the displacement deviation exceeds this value, obvious burrs can be seen on the donkey head displacement curve. Figure 5 and Figure 6 As shown in the figure, the red curve is the donkey head displacement curve, with the horizontal axis representing the product of angular velocity ω and time t, and the vertical axis representing the donkey head displacement; the blue curve is the donkey head load curve, with the horizontal axis representing the product of angular velocity ω and time t, and the vertical axis representing the donkey head displacement.

[0043] In this embodiment, the degree of deviation between the highest point of the donkey head displacement curve and the highest point of the normal donkey head displacement curve is: the deviation between the stroke time of the upper stroke of the donkey head displacement curve and the stroke time of the normal donkey head displacement curve, or the deviation between the stroke time of the lower stroke of the donkey head displacement curve and the stroke time of the normal donkey head displacement curve.

[0044] In this embodiment, the deviation between the stroke time on the donkey head displacement curve and the stroke time on the normal donkey head displacement curve is calculated as follows: the absolute value of the difference between the stroke time on the donkey head displacement curve and the stroke time on the normal donkey head displacement curve is divided by the stroke time on the normal donkey head curve.

[0045] In this embodiment, the deviation between the stroke time of the donkey head displacement curve and the stroke time of the normal donkey head displacement curve is calculated as follows: the absolute value of the difference between the stroke time of the donkey head displacement curve and the stroke time of the normal donkey head displacement curve is divided by the stroke time of the normal donkey head displacement curve.

[0046] In this embodiment, the offset threshold is set to 5%. When the offset of the point corresponding to the highest point of the donkey's head is greater than this value, a clear offset of the point corresponding to the highest point of the donkey's head displacement curve can be seen on the donkey's head displacement curve.

[0047] Under normal circumstances, the highest point of the gearbox (top dead center) is approximately located near the middle of the displacement curve. However, when the gearbox bearing malfunctions, such as... Figure 5 and Figure 6 As shown, the point corresponding to the highest position of the donkey's head is clearly shifted to the right, that is, there is a significant deviation in the time taken for the upstroke and the downstroke.

[0048] Step 3: Determine whether the donkey head load curve appears. The duration for which the deviation between the load value and the maximum load value on the donkey head load curve is less than the set load deviation threshold is less than the first set time, the duration for which the deviation between the load value and the minimum load value is less than the set load deviation threshold is less than the second set time, and the donkey head load curve shows dense spikes.

[0049] Gearbox bearing failure can cause vibrations in the meshing of gears during gearbox operation. In severe cases, the gear transmission in the gearbox may experience intermittent jamming and failure. When the gearbox bearing jams or fails, the load cannot be transferred from the gearbox to the walking beam and the pumping unit head, and the measured load value will decrease. When the gearbox bearing rotates back to normal, the load value suddenly increases again. Therefore, the load curve shows dense spikes and the stable part (upper and lower lines) becomes shorter.

[0050] If the deviation between the load value and the maximum load value on the donkey-head load curve is less than the set load deviation threshold, this segment of the curve can be considered stable near the maximum load value. This segment can be identified as an upward load stabilization line, and if its duration is less than the first set time, then the upward load stabilization line is considered short. Similarly, if the deviation between the load value and the minimum load value on the donkey-head load curve is less than the set load deviation threshold, this segment of the curve can be considered stable near the minimum load value. This segment can be identified as a downward load stabilization line, and if its duration is less than the second set time, then the downward load stabilization line is considered short.

[0051] When the first and second set times are relatively small, and the above conditions are met, the stability line of the upward process and the load stability line of the downward process are almost invisible on the indicator diagram.

[0052] In this embodiment, the method for determining that the donkey head load curve has dense spikes is as follows: when the load deviation of N4 points out of N3 points on the donkey head load curve is greater than the set load deviation threshold, it is determined that the donkey head load curve has dense spikes; the load deviation is the ratio of the absolute value obtained by subtracting the load value of the point from the average load of the points before and after the point to the maximum load value, and N3 > N4 ≥ 3.

[0053] Step 4: Determine whether the pumping unit indicator diagram is an irregular polygon.

[0054] When the gearbox bearing fails, it causes vibration in the meshing of the gears during operation, resulting in changes in the displacement of the pumping unit's head. The displacement curve of the head exhibits dense burrs. In severe cases, the gear transmission in the gearbox experiences intermittent jamming and failure, leading to uneven upstroke and downstroke times. This results in unstable operation and intermittent stoppages of the pumping unit. The highest point on the displacement curve shifts to the left or right and no longer falls in the middle of each stroke. When the gearbox bearing jams or fails, the load cannot be transferred from the gearbox to the pumping unit's walking beam and head, causing the measured load value to decrease. When the gearbox bearing rotates back to normal, the load value suddenly increases again. Therefore, the load curve exhibits dense burrs, and the stable portion (upward and downward lines) becomes shorter. The dynamometer diagram combines the abnormal changes in displacement and load, presenting them as an irregular polygon.

[0055] The indicator diagram when the bearing of the oil pumping unit gearbox is damaged is as follows: Figure 7 As shown in the figure, the indicator diagrams are all presented as irregular polygons.

[0056] If steps two, three, and four are all determined to be yes, then it can be determined that the gearbox bearing of the oil pumping unit is faulty.

[0057] In this embodiment, all thresholds are obtained by analyzing the displacement curves, load curves, and indicator diagrams of the pumping unit using statistical methods. For example, the displacement deviation threshold is set by obtaining multiple displacement curves when the pumping unit gearbox bearing fails, calculating the deviation between the displacement value at the corresponding burr location and the normal displacement value, obtaining the average value of all deviations, and setting the displacement deviation threshold based on the average value.

[0058] Through the above steps, the method for diagnosing gearbox bearing faults in the beam pumping unit of the present invention can determine whether the gearbox bearing is faulty based on the changes in the beam load curve, beam displacement curve and indicator diagram of the pumping unit. This method is simple and efficient, does not require manual inspection, saves labor costs, and enables more timely diagnosis of gearbox bearings, ensuring the normal operation of the pumping unit.

[0059] In addition, the beam pumping unit gearbox bearing diagnosis method of the present invention also triggers an alarm 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 the M strokes set before the certain moment, and the degree of the greaterness 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 degree 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 gearbox bearing faults in a beam pumping unit. This method can determine a gearbox bearing fault when the beam displacement curve exhibits dense burrs and the corresponding point at the highest point of the beam deviates from the normal beam displacement curve; the beam load curve exhibits dense burrs and the upward and downward stabilizing lines shorten or even disappear; and the pumping unit's indicator diagram shows an irregular polygon. Furthermore, the present invention proposes methods for judging the appearance of dense burrs on the beam displacement curve, the deviation of the corresponding point at the highest point of the beam from the normal beam displacement curve, and the determination of a sawtooth wavy line with a load curve varying within a certain range. These methods convert graphical features into numerical features, facilitating gearbox bearing fault diagnosis using computer programs and processors. Furthermore, the present invention also proposes an alarm method for detecting anomalies in the beam displacement and load curves, enabling timely detection of pumping unit malfunctions, prompting maintenance personnel to conduct inspections and repairs, and ensuring the normal operation of the pumping unit.

Claims

1. A method for diagnosing bearing faults in a beam pumping unit gearbox, characterized in that, Includes the following steps: Obtain the donkey head displacement curve, donkey head load curve and indicator diagram of the pumping unit. When the donkey head displacement curve, donkey head load curve and indicator diagram of a certain stroke simultaneously meet the following conditions, the gearbox bearing of the pumping unit is determined to be faulty. The donkey head displacement curve shows dense spikes, and the corresponding point of the highest point of the donkey head is offset from the corresponding point of the highest point of the donkey head on the normal donkey head displacement curve, and the degree of offset is greater than the set offset degree threshold. The duration for which the deviation between the load value and the maximum load value on the donkey head load curve is less than the set load deviation threshold is less than the first set time, the duration for which the deviation between the load value and the minimum load value is less than the set load deviation threshold is less than the second set time, and dense spikes appear on the donkey head load curve. The pumping unit's indicator diagram appears as an irregular polygon.

2. The method for diagnosing bearing faults in the gearbox of a beam pumping unit according to claim 1, characterized in that, If the displacement deviation of N2 points out of N1 points on the donkey head displacement curve is greater than the set displacement deviation threshold, then the donkey head displacement curve is determined to have dense burrs. The displacement deviation is the ratio of the absolute value obtained by subtracting the displacement value of the point from the average displacement of the points before and after the point to the total displacement value of the current stroke, and N1 > N2 ≥ 3.

3. The method for diagnosing bearing faults in the gearbox of a beam pumping unit according to claim 1, characterized in that, The degree of deviation between the highest point of the donkey head displacement curve and the highest point of the donkey head displacement curve in the normal donkey head displacement curve is: the deviation between the stroke time of the upper stroke of the donkey head displacement curve and the stroke time of the upper stroke of the normal donkey head displacement curve, or the deviation between the stroke time of the lower stroke of the donkey head displacement curve and the stroke time of the lower stroke of the normal donkey head displacement curve.

4. The method for diagnosing bearing faults in the gearbox of a beam pumping unit according to claim 3, characterized in that, The deviation between the stroke time on the donkey head displacement curve and the stroke time on the normal donkey head displacement curve is calculated as follows: the absolute value of the difference between the stroke time on the donkey head displacement curve and the stroke time on the normal donkey head displacement curve is divided by the stroke time on the normal donkey head displacement curve. The deviation between the stroke time on the donkey head displacement curve and the stroke time on the normal donkey head displacement curve is calculated as follows: the absolute value of the difference between the stroke time on the donkey head displacement curve and the stroke time on the normal donkey head displacement curve is divided by the stroke time on the normal donkey head displacement curve.

5. The method for diagnosing bearing faults in the gearbox of a beam pumping unit according to claim 1, characterized in that, The method for determining the presence of dense spikes in the donkey head load curve is as follows: when the load deviation of N4 points out of N3 points on the donkey head load curve is greater than the set load deviation threshold, the donkey head load curve is determined to have dense spikes; the load deviation is the ratio of the absolute value obtained by subtracting the load value of the point from the average load of the points before and after the point to the maximum load value, and N3 > N4 ≥ 3.

6. The method for diagnosing bearing faults in the gearbox of a beam pumping unit according to any one of claims 1-5, characterized in that, The normal donkey head displacement curve is the donkey head displacement curve when the pumping unit is not malfunctioning or the theoretical donkey head displacement curve.

7. The method for diagnosing bearing faults in the gearbox of a beam pumping unit according to any one of claims 1-5, 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.

8. The method for diagnosing bearing faults in the gearbox of a beam pumping unit according to any one of claims 1-5, characterized in that, An alarm will sound when the displacement of the pumping unit's head increases or remains unchanged during the downward phase of the head displacement curve.

9. The method for diagnosing bearing faults in the gearbox of a beam pumping unit according to any one of claims 1-5, characterized in that, An alarm is triggered when the maximum value of the donkey head load curve in the stroke exceeds the maximum value of the load curve in the previous stroke, and the degree of excess is greater than or equal to the first set threshold.

10. The method for diagnosing bearing faults in the gearbox of a beam pumping unit according to any one of claims 1-5, 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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