Fault diagnosis method for rotary steerable hydraulic system

Abstract

The application relates to a fault diagnosis method of a rotary steering hydraulic system, which comprises the following steps: selecting a corresponding motor according to the number of plungers of a plunger pump of the rotary steering hydraulic system; obtaining an empirical waveform pattern of phase current of any phase of a stator three-phase coil in a motor rotation process of the same number of pole pairs, and calculating an actual rotating speed of the motor according to the empirical waveform pattern; driving the plunger pump by using the selected motor, obtaining the pressure of the rotary steering hydraulic system, and obtaining an actual waveform pattern of phase current of any phase of the stator three-phase coil in the motor rotation process; if it is determined that the rotary steering hydraulic system is abnormal according to the pressure and the actual rotating speed, determining whether the plunger pump is abnormal and whether a pressure sensor is faulty according to the actual waveform pattern. The application realizes the purpose of evaluating whether the functions of key components of the hydraulic system are normal without disassembly.

Description

Technical Field

[0001] This invention belongs to the field of fault diagnosis technology, and specifically relates to a fault diagnosis method for a rotary guide hydraulic system. Background Technology

[0002] The hydraulic schematic diagram of the rotary guide hydraulic system is as follows: Figure 1 As shown, during the operation of the rotary guide hydraulic system, the motor drives the piston pump to deliver hydraulic oil from the compensator assembly to the piston cylinder, pushing the piston outward. Before the piston reaches the limit, the pressure in the rotary guide hydraulic system increases slowly. After the piston reaches the limit, the hydraulic oil begins to return to the compensator assembly through the throttle valve on the valve seat of the motor assembly, forming an oil circuit circulation. The flowing hydraulic oil generates pressure through the throttle valve, and this pressure is proportional to the displacement of the piston pump. The relief valve is generally not open, and it will only open when the pressure in the hydraulic system exceeds the pressure design value.

[0003] When a rotary guide hydraulic system is working normally, the motor current corresponds directly to the hydraulic system pressure and the motor speed. When the hydraulic system malfunctions: the hydraulic system pressure, motor speed, and motor current no longer match, showing significant differences from normal values. Based on this characteristic, maintenance personnel can easily detect hydraulic system abnormalities, but locating the fault point within the hydraulic system is more difficult because critical components along the hydraulic linkage can potentially fail. Therefore, if... Figure 2 As shown, when an abnormality occurs in the rotary guide hydraulic system, the hydraulic system needs to be disassembled and all its components inspected. The piston pump is the key component that generates pressure in the hydraulic system and is also the most complex component. Its working condition (the efficiency of the piston pump) often requires a dedicated pump tester to be tested. Therefore, the existing method of disassembling the hydraulic system and inspecting each component is not only time-consuming and labor-intensive, but also requires various specialized testing equipment to evaluate whether the hydraulic system components are functioning properly. Summary of the Invention

[0004] In order to solve all or some of the above problems, the present invention aims to provide a fault diagnosis method for a rotary guide hydraulic system. The present invention achieves the goal of assessing whether the functions of key components of the hydraulic system are normal without disassembly.

[0005] According to one aspect of the present invention, a fault diagnosis method for a rotary guide hydraulic system is provided, comprising: Select the appropriate motor based on the number of plungers in the plunger pump of the rotary guide hydraulic system; The empirical waveform of the phase current of any one phase of the stator three-phase coil during one revolution of the motor with the same number of pole pairs is obtained, and the actual speed of the motor is calculated based on the empirical waveform. Using the selected motor to drive the plunger pump, the pressure of the rotary guide hydraulic system and the actual waveform of the phase current of any one phase of the stator three-phase coil during one revolution of the motor are obtained. If an abnormality is determined in the rotary guide hydraulic system based on the pressure and the actual rotational speed, then the actual waveform graph is used to determine whether the piston pump is abnormal and whether the pressure sensor is faulty.

[0006] Furthermore, obtaining the empirical waveform of the phase current of any one phase of the stator three-phase coil during one revolution of the motor, and calculating the actual speed of the motor based on the empirical waveform, further includes: Based on experience, the empirical waveform diagram of the phase current of any one phase in the three-phase stator coil during one revolution of the motor is obtained. The actual speed of the motor is calculated based on the empirical waveform and the number of pole pairs of the motor.

[0007] Furthermore, the step of calculating the actual speed of the motor based on the empirical waveform and the number of pole pairs of the motor further includes: The period of current variation with time is calculated based on the empirical waveform; and The actual rotational speed of the motor is calculated based on the cycle and the number of pole pairs of the motor.

[0008] Furthermore, the calculation of the actual rotational speed of the motor based on the period and the number of pole pairs of the motor specifically involves: The actual rotational speed of the motor is equal to the product of 60, the reciprocal of the period in seconds, and the reciprocal of the number of pole pairs of the motor. The unit of the actual rotational speed of the motor is revolutions per minute.

[0009] Furthermore, the specific steps of selecting the appropriate motor based on the number of plungers in the plunger pump of the rotary guide hydraulic system are as follows: Select a motor whose number of pole pairs is equal to the number of pistons in the piston pump of the rotary steered hydraulic system.

[0010] Furthermore, before determining whether the rotary guide hydraulic system is abnormal based on the pressure and the actual rotational speed, and before determining whether the piston pump is abnormal based on the actual waveform graph, and whether the pressure sensor is faulty, the method further includes: Determine whether there is any abnormality in the rotary guide hydraulic system based on the actual rotational speed and the pressure.

[0011] Furthermore, if an abnormality is determined in the rotary guide hydraulic system based on the pressure and the actual rotational speed, then determining whether the piston pump is abnormal based on the actual waveform graph and determining whether the pressure sensor is faulty further includes: If the rotary guide hydraulic system is determined to be abnormal based on the pressure and the actual rotation speed, then the piston pump is determined to be abnormal based on the actual waveform and the empirical waveform. If the plunger pump is faulty, replace the plunger pump and then check the pressure sensor for faultyness again. If the plunger pump is normal, then the pressure sensor is determined to be faulty.

[0012] Furthermore, if the rotary guide hydraulic system is determined to be abnormal based on the pressure and the actual rotational speed, then determining whether the piston pump is abnormal based on the actual waveform and the empirical waveform specifically involves: If the rotary guide hydraulic system is determined to be abnormal based on the pressure and the actual rotation speed, and the peak value of the actual waveform is equal to the peak value of the empirical waveform, and the number of peak values ​​of the actual waveform is less than the number of peak values ​​of the empirical waveform, then it is determined that some pistons of the piston pump have failed. If the rotary guide hydraulic system is determined to be abnormal based on the pressure and the actual rotation speed, and the peak value of the actual waveform is less than the peak value of the empirical waveform, and the number of peak values ​​of the actual waveform is equal to the number of peak values ​​of the empirical waveform, then it is determined that the piston pump has a decrease in pumping efficiency due to wear.

[0013] Furthermore, the step of replacing the plunger pump and then re-evaluating whether the pressure sensor is faulty if the plunger pump is malfunctioning specifically involves: If the plunger pump is malfunctioning, replace it with a normal plunger pump. Then, determine whether the hydraulic system is malfunctioning based on the pressure of the rotary guide hydraulic system corresponding to the normal plunger pump and the actual speed of the motor. If the hydraulic system is still malfunctioning, then the pressure sensor is determined to be faulty.

[0014] As can be seen from the above technical solution, the fault diagnosis method for a rotary guide hydraulic system provided by the present invention has the following beneficial effects: This invention can accurately identify whether the efficiency of a piston pump is normal by measuring the phase current waveform of any one phase in the three-phase coil of the motor stator; it can infer whether the pressure sensor is working properly based on the motor speed, the pressure of the rotary guide hydraulic system and the evaluation effect of the piston pump efficiency; this invention achieves the goal of evaluating the function of key components of the hydraulic system without disassembly. Attached Figure Description

[0015] Figure 1Hydraulic schematic diagram of a rotary guide hydraulic system; Figure 2 This is a schematic diagram illustrating a handling method for abnormal situations in a rotary guide hydraulic system in the prior art; Figure 3 This is a schematic diagram of energy transmission in a rotary guide hydraulic system. Figure 4 A flowchart of a fault diagnosis method for a rotary guide hydraulic system; Figure 5 This is a schematic diagram illustrating a method for handling abnormalities in the rotary guide hydraulic system, as described in an embodiment of the present invention. Figure 6 This is an empirical waveform diagram of the phase current of any one phase in the three-phase stator coil during one revolution of the motor. Figure 7 This is a schematic diagram comparing empirical waveforms and actual waveforms. Detailed Implementation

[0016] To better understand the purpose, structure, and function of this invention, a fault diagnosis method for a rotary guide hydraulic system of this invention will be described in further detail below with reference to the accompanying drawings.

[0017] The embodiments of the present invention are based on, as follows Figure 3 The energy transfer diagram shown reveals relevant factors associated with the failure of the rotary guide hydraulic system.

[0018] Specifically, the input power of the hydraulic system drive motor is set to P. 电机输入 The voltage of the drive motor is U 电机 The current of the drive motor is I 电机 The relationship between the three is as follows: P 电机输入 =U 电机 I 电机 Formula 1 Set the output power of the drive motor to P 电机输出 The torque of the drive motor is Te, and the speed of the drive motor is R. PM The efficiency of the drive motor is Then the following equation exists: P 电机输出 =P 电机输入 =Te R PM Formula 2 Set the input power of the plunger pump to P. 泵输入 The energy transfer efficiency from the drive motor to the plunger pump is Then, the following relationship exists between the three: P 泵输入 =P 电机输出 Formula 3 Set the output power of the plunger pump to P 泵输出 The pressure of the rotary guide hydraulic system is Pa. 液压 The displacement of the plunger pump is F 液压 The efficiency of the plunger pump is Then the following relationship exists: P 泵输出 =P 泵输入 =Pa 液压 Formula 4 Based on the foregoing reasoning, we can obtain the following equation: P 电机输入 =U 电机 I 电机 =Pa 液压 Formula 5 As can be seen from Equation 5, the motor current I 电机 Pressure Pa of rotary guide hydraulic system 液压 The displacement F of the plunger pump 液压 There is a positive correlation. Based on this, the pressure of the hydraulic system and the displacement of the piston pump can be determined by measuring the current of the motor.

[0019] Among them, L 节流阀 The flow resistance value of the throttle valve assembly is represented by R. PM As shown above, the speed of the drive motor is represented by Rev, and the displacement of the plunger pump per revolution is represented by Rev. Then, the following equations six and seven have the following relationship: Pa 液压 ≈F 液压 L 节流阀 Formula Six F 液压 =R PM Rev. 7 According to Equation 7, the speed R of the drive motor is... PM With the displacement F of the plunger pump 液压 Positive correlation, displacement F of the plunger pump 液压 And the pressure Pa of the rotary guide hydraulic system 液压 Therefore, when the rotary guide hydraulic system is functioning normally, there is a matching relationship between the speed of the drive motor and the pressure of the rotary guide hydraulic system. Here, the speed of the drive motor refers to the actual speed of the drive motor.

[0020] For a plunger pump, each set of plunger oil circuits consists of three parts: the plunger, the suction check valve, and the discharge check valve. During normal operation, the swashplate rotates under the drive of the motor, causing the plunger to reciprocate up and down. When the plunger moves downwards, due to the plunger's suction effect, a negative pressure is generated in the plunger chamber, opening the suction check valve and allowing hydraulic oil to enter the plunger chamber. When the plunger moves upwards, the hydraulic oil is compressed, generating high pressure, thus closing the suction check valve and simultaneously opening the discharge check valve, discharging the hydraulic oil from the plunger chamber from the plunger pump outlet, establishing an oil circuit circulation. During normal operation, the plunger pump operates at a stable pressure, and the motor rotates at a constant speed. When the motor drives the swashplate, causing the plunger to move upwards, the following conditions can be approximated: the plunger discharge pressure is approximately constant, and the plunger discharge volume is approximately constant. Based on this, the power of the plunger pump at this time can be calculated using the following formula: P 柱塞 =Pa 柱塞 F 柱塞 Formula 8 In Formula 8, P 柱塞 This indicates the power of the plunger pump, in Pa. 柱塞 F represents the discharge pressure of the plunger pump. 柱塞 This indicates the oil discharge flow rate of the plunger pump. At this time, the plunger pump is driven entirely by the motor, so the power of the motor is proportional to the power of the plunger pump. If the plunger pump cannot work properly, it is manifested by the plunger discharge pressure and discharge flow rate being close to 0. At this time, the power of the motor is small and the amplitude of the motor phase current is low. Based on this, it can be determined whether the plunger pump can work properly.

[0021] Based on the aforementioned principles, embodiments of the present invention provide a fault diagnosis method for a rotary guide hydraulic system, such as... Figures 4-5 As shown, the method includes the following steps: Step S001: Select the appropriate motor according to the number of plungers in the plunger pump of the rotary guide hydraulic system; Step S002: Obtain the empirical waveform of the phase current of any one phase in the three-phase stator coil during one revolution of the motor, and calculate the actual speed of the motor based on the empirical waveform. Step S003: Using the selected motor to drive the plunger pump, obtain the pressure of the rotary guide hydraulic system and the actual waveform of the phase current of any one phase of the stator three-phase coil during one revolution of the motor. Step S004: If the rotary guide hydraulic system is found to be abnormal based on the pressure and actual speed, then determine whether the piston pump is abnormal based on the actual waveform graph, and whether the pressure sensor is faulty.

[0022] Traditional troubleshooting methods for rotary steering hydraulic systems require disassembling the system and then inspecting critical components using specialized testing equipment. This invention eliminates the need for disassembly. By measuring the phase current signal of the motor driving the piston pump using a current probe, and comparing this phase current signal with the pressure of the rotary steering hydraulic system, it's possible to quickly and accurately determine if the piston pump is malfunctioning. Only when the piston pump is functioning normally, but the actual motor speed and the pressure of the rotary steering hydraulic system do not match, is it suspected that the pressure sensor may be faulty. In this case, the hydraulic system can be disassembled and the pressure sensor inspected.

[0023] In this embodiment, the actual rotational speed of the motor is used, so there is no need to question the accuracy of the actual rotational speed. When using a measured rotational speed, it is also necessary to determine whether the measured rotational speed is accurate. Thus, assuming the measured rotational speed is accurate, that is, equal to the actual rotational speed, the matching between the measured rotational speed and the pressure of the rotary guide hydraulic system is used to determine whether the rotary guide hydraulic system is malfunctioning.

[0024] The rotary guide hydraulic system uses a motor-driven piston pump to circulate hydraulic oil. The circulating oil passes through a throttle valve to generate pressure; an internal pressure sensor monitors the internal pressure. When the hydraulic system malfunctions, it manifests as a mismatch between the motor's actual speed and the system's pressure. Numerous potential fault points exist, making troubleshooting complex. This invention measures the phase current of the drive motor in the hydraulic system. Based on this phase current, the motor's actual speed can be obtained, effectively assessing the piston pump efficiency and verifying the pressure sensor's functionality.

[0025] Specifically, step S001, which selects the appropriate motor based on the number of plungers in the rotary guide hydraulic system's plunger pump, involves selecting a motor with a pole pair number equal to the number of plungers in the rotary guide hydraulic system's plunger pump.

[0026] Specifically, if the number of plungers in the plunger pump is set to N, then a motor with a corresponding number of pole pairs is selected to drive it. In this way, by matching the current period of the N-pole pair motor with the rotation period of the plunger pump, it is possible to intuitively reflect whether each group of plungers in the plunger pump is working properly.

[0027] Taking a 3-pole motor and a 3-plunger plunger pump as an example: Assuming a uniform load, when the 3-pole motor rotates one revolution (360°), the phase current of any one phase changes 3 times in a period of (120°). Therefore, the phase current can reflect the motor load in the 120° sector. The 3 plungers of the plunger pump are distributed in 120° sectors. Therefore, the magnitude of the motor phase current in each 120° sector can accurately reflect the power of the plunger and assess whether the plunger function is normal.

[0028] Step S002 obtains the empirical waveform of the phase current of any one phase of the stator three-phase coil during one revolution of the motor, and calculates the actual speed of the motor based on the empirical waveform, which further includes: Based on experience, the empirical waveform diagram of the phase current of any one phase in the three-phase stator coil during one revolution of the motor is obtained; The actual speed of the motor is calculated based on the empirical waveform and the number of pole pairs of the motor.

[0029] Specifically, the actual speed of the motor is calculated based on empirical waveform graphs and the number of pole pairs of the motor as follows: the period of current change with time is calculated based on empirical waveform graphs; and the actual speed of the motor is calculated based on the period and the number of pole pairs of the motor.

[0030] The actual speed of the motor is calculated based on the period and the number of pole pairs. Specifically, the actual speed of the motor is equal to the product of 60, the reciprocal of the period in seconds, and the reciprocal of the number of pole pairs. The unit of the actual speed of the motor is revolutions per minute.

[0031] Specifically, let the actual speed of the motor be n, in revolutions per minute (r / min), the period be T, in seconds (s), and the number of pole pairs of the motor be equal to the number of plungers in the plunger pump, denoted by N. n=60 / (TN) Equation 9 The empirical waveform of the phase current of any phase in the three-phase stator coil during one revolution of a motor with 3 pole pairs is shown below. Figure 6 As shown, where, Figure 6 The negative value indicates that the direction is opposite to the corresponding positive value. In this embodiment, the period of current change is obtained by using the empirical waveform of the phase current of any one phase in the three-phase coil of the stator during one rotation of the motor. Then, the actual speed of the motor is calculated based on the period of current change and the number of pole pairs of the motor.

[0032] As mentioned above, there is a matching relationship between the actual speed of the drive motor and the pressure of the rotary guide hydraulic system. Therefore, step S003 obtains the pressure of the rotary guide hydraulic system. The pressure and the actual speed of the motor calculated above can be used to determine whether the rotary guide hydraulic system is abnormal.

[0033] Therefore, before determining whether the rotary guide hydraulic system is abnormal based on the pressure and actual rotational speed in step S004, and before determining whether the piston pump is abnormal based on the actual waveform graph, and before determining whether the pressure sensor is faulty, the method of this embodiment further includes: Determine if there are any abnormalities in the rotary guide hydraulic system based on the actual rotational speed and pressure.

[0034] The actual rotational speed at this point is the speed calculated according to Equation 9. Then, the matching of the actual rotational speed and the pressure of the rotary guide hydraulic system is used to determine whether the rotary guide hydraulic system is malfunctioning. This embodiment eliminates the possibility of mistakenly identifying the rotary guide hydraulic system as malfunctioning due to inaccurate rotational speed.

[0035] In addition, for cases where the motor speed is measured, it is also necessary to determine whether the measured speed is accurate. In order to determine whether the rotary guide hydraulic system is abnormal, the matching between the measured speed and the pressure of the rotary guide hydraulic system is used, provided that the measured speed is accurate.

[0036] The main causes of abnormalities in the rotary steering hydraulic system are: 1. Decreased plunger pump efficiency μ. This decrease can be due to two reasons: a) failure of one or more plungers due to oil cleanliness issues; b) decreased pumping efficiency due to plunger pump wear. 2. Under normal conditions, a malfunctioning pressure sensor can cause a mismatch between the actual motor speed and the pressure in the rotary steering hydraulic system.

[0037] As mentioned above, a malfunctioning piston pump manifests as a low amplitude of the motor's phase current. Therefore, in this embodiment of the invention, the piston pump is driven by a selected motor, and the actual waveform of the phase current of any one phase of the stator's three-phase coil during one revolution of the motor is obtained. The malfunction of the piston pump can then be determined based on this actual waveform. Conversely, if the rotary guide hydraulic system is malfunctioning while the piston pump is functioning normally, the problem lies with the pressure sensor in the rotary guide hydraulic system.

[0038] Specifically, if step S004 determines that there is an abnormality in the rotary guide hydraulic system based on the pressure and actual rotational speed, then further steps include determining whether the piston pump is abnormal based on the actual waveform graph and whether the pressure sensor is faulty, including: Step S0041: If the rotary guide hydraulic system is found to be abnormal based on the pressure and actual speed, then the piston pump is determined to be abnormal based on the actual waveform graph and the empirical waveform graph. Step S0042: If the plunger pump is malfunctioning, replace the plunger pump and then check the pressure sensor for faults again. Step S0043: If the plunger pump is normal, the pressure sensor is determined to be faulty.

[0039] When an anomaly is determined in the rotary guide hydraulic system based on actual speed and pressure, this embodiment of the invention can determine whether the piston pump is malfunctioning based on actual and empirical waveforms. After replacing the piston pump, the replacement piston pump is driven by a motor to obtain the actual waveform of the phase current and the system pressure again. Then, the pressure sensor is again assessed based on the obtained actual waveform and pressure. If the piston pump is determined to be functioning correctly based on the actual and empirical waveforms, but the actual speed and pressure of the motor are indeed mismatched, then the pressure sensor is determined to be malfunctioning.

[0040] This invention achieves the goal of accurately identifying whether a piston pump in a hydraulic system has failed without disassembling the system. Piston pump failures account for over 60% of hydraulic system malfunctions. Furthermore, because this application uses the actual rotational speed, it eliminates the problem of mismatch between the measured rotational speed and the pressure of the rotary guide hydraulic system due to inaccurate speed measurement. If a measured rotational speed is used, it is also necessary to determine whether the measured speed is inaccurate. That is, the method of this invention can accurately identify whether the piston pump in the hydraulic system has failed and whether the motor speed measurement is accurate without disassembling the hydraulic system. If neither of these two situations exists, it is determined that the pressure sensor may be faulty. In this case, the hydraulic system is disassembled and the pressure sensor is tested.

[0041] Therefore, by measuring the phase current waveform of any one phase in the three-phase coil of the motor stator, this embodiment of the invention can accurately identify whether the piston pump efficiency is normal. Based on the evaluation results of the motor speed and piston pump efficiency, it can further infer whether the pressure sensor is working properly. This embodiment of the invention achieves the goal of evaluating the function of key components of the hydraulic system without disassembly.

[0042] Specifically, in step S0041, if an abnormality is determined in the rotary guide hydraulic system based on the pressure and actual rotational speed, then the abnormality of the piston pump is determined based on the actual waveform graph and the empirical waveform graph. If an abnormality is found in the rotary steering hydraulic system based on pressure and actual speed, and the peak value of the actual waveform is equal to the peak value of the empirical waveform, and the number of peak values ​​of the actual waveform is less than the number of peak values ​​of the empirical waveform, then it is determined that some pistons of the piston pump have failed. If an abnormality is determined in the rotary guide hydraulic system based on pressure and actual speed, and the peak value of the actual waveform is less than the peak value of the empirical waveform, and the number of peak values ​​of the actual waveform is equal to the number of peak values ​​of the empirical waveform, then it is determined that the piston pump has a decrease in pumping efficiency due to wear.

[0043] As mentioned above, there are two situations where the efficiency of a plunger pump decreases: failure of one or more plungers, and decreased pumping efficiency due to wear. In this embodiment of the invention, the abnormal condition of the plunger pump can be determined by comparing the actual waveform with empirical waveforms.

[0044] Specifically, in cases where an abnormality has been determined in the rotary guide hydraulic system, such as Figure 7 As shown, if the peak value of the actual waveform is equal to the peak value of the empirical waveform, and the number of peak values ​​in the actual waveform is less than the number of peak values ​​in the empirical waveform, then it is determined that there is one or more abnormalities in the plunger pump. Figure 7 It has 3 plungers, and the corresponding number of motor pole pairs is 3. Figure 7 The graph on the left is an empirical waveform graph. Figure 7 The right-hand image shows the actual waveform. Figure 7 It can be seen that the actual waveform only has two peaks during one rotation of the motor, which indicates that one of the three plungers in the plunger pump has failed.

[0045] Refer again Figure 7 , Figure 7 If the peak value of the phase current in the empirical waveform is 1A, and the peak value of the actual waveform is less than that of the empirical waveform, but the number of peak values ​​in the actual waveform is equal to the number of peak values ​​in the empirical waveform, then it is determined that the plunger pump has a problem of reduced pumping efficiency due to wear.

[0046] Specifically, in step S0042, if the plunger pump is malfunctioning, the plunger pump is replaced and the pressure sensor is checked again to determine if it is faulty. If the piston pump is malfunctioning, replace it with a normal piston pump. Then, determine whether the hydraulic system is malfunctioning based on the pressure of the rotary guide hydraulic system corresponding to the normal piston pump and the actual speed of the motor. If the hydraulic system is still malfunctioning, then the pressure sensor is faulty.

[0047] If the piston pump is determined to be faulty based on actual and experienced waveform data, it is also necessary to determine whether the pressure sensor of the rotary steering hydraulic system is malfunctioning. In this case, the piston pump needs to be replaced with a known good one. The pressure and actual motor speed collected after replacing the piston pump should then be used to reassess the hydraulic system for any abnormalities. If the rotary steering hydraulic system still exhibits abnormalities after replacing the piston pump, then the pressure sensor of the rotary steering hydraulic system is likely also faulty.

[0048] Finally, if the rotary guide hydraulic system is found to be abnormal based on the pressure and actual speed, and the piston pump is found to be normal based on the actual waveform and empirical waveform, then the problem is most likely a fault in the pressure sensor, which can be calibrated and verified.

[0049] Finally, if step S004 determines that there is an abnormality in the rotary guide hydraulic system based on the pressure and actual rotational speed, and then determines whether the piston pump is abnormal based on the actual waveform graph, and whether the pressure sensor is faulty, the method of this embodiment of the invention further includes: By modifying key components in the piston pump and measuring the phase current characteristics of the motor when driving the piston pump, a phase current characteristic database is established. Subsequently, when the hydraulic system detects a decrease in piston pump efficiency, the failed key components in the piston pump can be quickly diagnosed based on the characteristic current waveforms stored in the phase current characteristic database.

[0050] Specifically, for example, by changing the plunger, suction check valve, or discharge check valve in the plunger pump, and using a motor with the same number of pole pairs as the number of plungers in the plunger pump to drive the changed plunger, the phase current characteristics of any one phase of the stator three-phase coil during one revolution of the motor can be obtained. Based on the obtained phase current characteristics, a phase current characteristic library can be established, and then when it has been determined that the plunger pump efficiency has decreased, the specific faulty component of the plunger pump can be obtained.

[0051] Therefore, by measuring the phase current waveform of any one phase in the three-phase coil of the motor stator, this embodiment of the invention can accurately identify whether the piston pump efficiency is normal; based on the motor speed, the pressure of the rotary guide hydraulic system, and the evaluation effect of the piston pump efficiency, it can be inferred whether the pressure sensor is working properly; this embodiment of the invention achieves the purpose of evaluating whether the functions of key components of the hydraulic system are normal without disassembly.

[0052] It should be noted that, unless otherwise stated, the technical or scientific terms used in this application should have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered within the scope of the claims and specification of the present invention. In particular, as long as there is no structural conflict, the various technical features mentioned in the embodiments can be combined in any way. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A fault diagnosis method for a rotary guide hydraulic system, characterized in that, The rotary guide hydraulic system is powered by a motor-driven piston pump, which forms a hydraulic oil circulation loop. The circulating oil circuit generates pressure through a throttle valve. The method includes: Select the appropriate motor based on the number of plungers in the plunger pump of the rotary guide hydraulic system; The empirical waveform of the phase current of any one phase of the stator three-phase coil during one revolution of the motor is obtained, and the actual speed of the motor is calculated based on the empirical waveform. Using the selected motor to drive the plunger pump, the pressure of the rotary guide hydraulic system and the actual waveform of the phase current of any one phase of the stator three-phase coil during one revolution of the motor are obtained. Based on whether the actual rotational speed and the pressure match, determine whether there is any abnormality in the rotary guide hydraulic system; If an abnormality is determined in the rotary guide hydraulic system based on the pressure and the actual rotational speed, then the abnormality of the piston pump is determined based on the actual waveform graph, and the fault of the pressure sensor is determined based on the actual waveform graph. The pressure sensor is used to monitor the pressure. If an abnormality is determined in the rotary guide hydraulic system based on the pressure and the actual rotational speed, then determining whether the piston pump is abnormal based on the actual waveform and whether the pressure sensor is faulty further includes: If the rotary guide hydraulic system is determined to be abnormal based on the pressure and the actual rotation speed, then the piston pump is determined to be abnormal based on the actual waveform and the empirical waveform. If the plunger pump is faulty, replace the plunger pump and then check the pressure sensor for faultyness again. If the plunger pump is normal, then the pressure sensor is determined to be faulty.

2. The method according to claim 1, characterized in that, The step of obtaining the empirical waveform of the phase current of any one phase of the stator three-phase coil during one revolution of the motor, and calculating the actual speed of the motor based on the empirical waveform, further includes: Based on experience, the empirical waveform diagram of the phase current of any one phase in the three-phase stator coil during one revolution of the motor is obtained. The actual speed of the motor is calculated based on the empirical waveform and the number of pole pairs of the motor.

3. The method according to claim 2, characterized in that, The step of calculating the actual speed of the motor based on the empirical waveform and the number of pole pairs of the motor further includes: The period of current variation with time is calculated based on the empirical waveform; and The actual rotational speed of the motor is calculated based on the cycle and the number of pole pairs of the motor.

4. The method according to claim 3, characterized in that, The calculation of the actual rotational speed of the motor based on the period and the number of pole pairs of the motor is specifically as follows: The actual rotational speed of the motor is equal to the product of 60, the reciprocal of the period in seconds, and the reciprocal of the number of pole pairs of the motor. The unit of the actual rotational speed of the motor is revolutions per minute.

5. The method according to claim 1, characterized in that, The specific steps for selecting the appropriate motor based on the number of plungers in the plunger pump of the rotary guide hydraulic system are as follows: Select a motor whose number of pole pairs is equal to the number of pistons in the piston pump of the rotary steered hydraulic system.

6. The method according to claim 1, characterized in that, If the rotary guide hydraulic system is determined to be abnormal based on the pressure and the actual rotational speed, then determining whether the piston pump is abnormal based on the actual waveform and the empirical waveform specifically involves: If the rotary guide hydraulic system is determined to be abnormal based on the pressure and the actual rotation speed, and the peak value of the actual waveform is equal to the peak value of the empirical waveform, and the number of peak values ​​of the actual waveform is less than the number of peak values ​​of the empirical waveform, then it is determined that some pistons of the piston pump have failed. If the rotary guide hydraulic system is determined to be abnormal based on the pressure and the actual rotation speed, and the peak value of the actual waveform is less than the peak value of the empirical waveform, and the number of peak values ​​of the actual waveform is equal to the number of peak values ​​of the empirical waveform, then it is determined that the piston pump has a decrease in pumping efficiency due to wear.

7. The method according to claim 1, characterized in that, If the plunger pump is malfunctioning, the procedure of replacing the plunger pump and then re-evaluating whether the pressure sensor is faulty is as follows: If the plunger pump is malfunctioning, replace it with a normal plunger pump. Then, determine whether the rotary guide hydraulic system is malfunctioning based on the pressure of the rotary guide hydraulic system corresponding to the normal plunger pump and the actual speed of the motor. If the rotary guide hydraulic system is still malfunctioning, then the pressure sensor is determined to be faulty.

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