A hydraulic control system for a rotary drilling rig and a rotary drilling rig

Abstract

This application discloses a hydraulic control system for a rotary drilling rig and a rotary drilling rig itself, relating to the field of rotary drilling rig technology. The hydraulic control system includes a power head motor with a forward rotation port and a reverse rotation port. The forward rotation port is connected to a forward rotation port oil circuit, and the reverse rotation port is connected to a reverse rotation port oil circuit. When the power head motor reverses, the hydraulic oil in the forward rotation port oil circuit flows to the oil tank through the return port. The hydraulic control system also includes a balance valve assembly and a replenishment oil circuit. The balance valve assembly is located in the forward rotation port oil circuit and is used to generate pressure when the drill rod releases its elastic torsional force to resist drill rod reset. The replenishment oil circuit is connected to the return port and the reverse rotation port oil circuit and is used to replenish the hydraulic oil from the return port to the reverse rotation port to prevent the power head motor from sucking in cavitation. The above-mentioned hydraulic control system for a rotary drilling rig solves the problem that after forward drilling is completed, the drill rod's elastic torsional rebound causes the power head to reverse rapidly, resulting in motor stall and cavitation.

Description

Technical Field

[0001] This application relates to the field of rotary drilling rig technology, and in particular to a hydraulic control system for a rotary drilling rig and a rotary drilling rig. Background Technology

[0002] Please see Figure 1 A rotary drilling rig is a heavy equipment used for pile foundation construction. It mainly consists of a main chassis 1, a power head 2, a drill rod 3, and drilling tools 4.

[0003] Please refer to the following: Figure 2 During deep hole drilling with a rotary drilling rig, drill rod 3 (thin-walled telescopic drill rod) extends to the bottom of the hole. During forward drilling, the power head 2 drives drill rod 3, which in turn drives the drill string 4 clockwise. When transmitting torque from the power head 2, the slender drill rod 3 undergoes elastic torque deformation before transmitting torque to the drill string 4 for cutting through rock or soil layers. However, please refer to [further details omitted]. Figure 3 and Figure 4 After drilling is completed in the forward direction, the drill bit 4 remains embedded in the rock layer. At this point, the clamping force is greater than the elastic torsional force of drill rod 3. Although drilling has stopped, the elastic torsional force of drill rod 3 is still retained. Please refer to [further details]. Figure 5 and Figure 6 Due to operational requirements, the power head 2 needs to be reversed before lifting the drill rod 3. At the moment the power head 2 is reversed, the drill teeth of the drill bit 4 disengage from the embedded layer, and the elastic torsional force of the drill rod 3 is suddenly released, causing the power head 2 to reverse rapidly. The hydraulic motor is also passively reversed rapidly, causing the motor to stall and suck in air, resulting in cavitation damage to the drilling rig, reduced system efficiency, abnormal vibration and noise, and other hazards. Utility Model Content

[0004] The purpose of this application is to provide a hydraulic control system for a rotary drilling rig and a rotary drilling rig in general, which solves the problem that after the forward drilling is completed, the drill rod rebounds due to elastic twisting, causing the power head to reverse rapidly, resulting in the power head motor stalling and the motor sucking in air.

[0005] To achieve the above objectives, this application provides a hydraulic control system for a rotary drilling rig, including a power head motor for driving the drill rod to rotate forward and backward. The power head motor has a forward rotation port and a reverse rotation port. The forward rotation port is connected to a forward rotation port oil circuit, and the reverse rotation port is connected to a reverse rotation port oil circuit. When the power head motor reverses, the hydraulic oil in the forward rotation port oil circuit flows to the oil tank through the return port. The hydraulic control system for the rotary drilling rig also includes:

[0006] The balance valve assembly, located in the forward rotation port oil circuit, is used to generate pressure when the drill pipe releases its elastic torsional force to resist the drill pipe's return to its original position.

[0007] The oil replenishment circuit is connected to the oil return port and the reverse port oil circuit. It is used to replenish the hydraulic oil from the oil return port to the reverse port to prevent the power head motor from sucking in cavitation.

[0008] In some embodiments, the balance valve assembly includes a relief valve located in the forward rotation port oil passage, which is used to open when the pressure in the forward rotation port oil passage reaches a set threshold.

[0009] In some embodiments, the relief valve is provided with a control port, which is connected to the reverse port oil circuit, so that the relief valve opens when it receives a preset hydraulic oil signal from the reverse port oil circuit.

[0010] In some embodiments, a throttle valve and a pressure-stabilizing check valve are provided on the oil line between the control oil port and the reverse oil port.

[0011] In some embodiments, the balance valve assembly further includes a forward rotation valve, which is connected in parallel with the relief valve. The forward rotation valve is used to supply hydraulic oil through the forward rotation port oil circuit to the forward rotation port to realize the forward rotation of the power head motor.

[0012] In some embodiments, a replenishing oil check valve is provided on the replenishing oil line, and the conduction direction of the replenishing oil check valve is from the return oil port to the reverse oil port.

[0013] In some embodiments, a return back pressure valve is provided on the oil line between the replenishment oil line and the oil tank. The return back pressure valve is used to generate pressure so that the hydraulic oil at the return port is replenished into the reverse port through the replenishment check valve.

[0014] In some embodiments, the hydraulic control system of the rotary drilling rig further includes a replenishing accumulator, which is connected to a replenishing oil circuit. The replenishing accumulator is used to release the stored hydraulic oil into the replenishing oil circuit when the power head motor is passively reversed.

[0015] In some embodiments, the hydraulic control system of the rotary drilling rig further includes a pressure sensor and a controller. The pressure sensor is located in the forward rotation port oil circuit and is used to detect the pressure in the forward rotation port oil circuit. The controller is communicatively connected to the pressure sensor and the balance valve assembly and is used to control the opening pressure of the balance valve assembly according to the pressure signal detected by the pressure sensor.

[0016] This application also provides a rotary drilling rig, including the rotary drilling rig hydraulic control system of any of the above.

[0017] Compared to the aforementioned background technology, the hydraulic control system for rotary drilling rigs provided in this application includes a power head motor for driving the drill rod to rotate forward and backward. The power head motor has a forward rotation port and a reverse rotation port. The forward rotation port is connected to a forward rotation port oil circuit, and the reverse rotation port is connected to a reverse rotation port oil circuit. When the power head motor reverses, the hydraulic oil in the forward rotation port oil circuit flows to the oil tank through the return port. The hydraulic control system for rotary drilling rigs also includes a balance valve assembly and a replenishment oil circuit. The balance valve assembly is located in the forward rotation port oil circuit and is used to generate pressure when the drill rod releases its elastic torsional force to resist drill rod resetting. The replenishment oil circuit is connected to the return port and the reverse rotation port oil circuit and is used to replenish the hydraulic oil from the return port to the reverse rotation port to prevent the power head motor from sucking in cavitation.

[0018] This design, by adding a balance valve assembly to the forward rotation port oil circuit of the power head motor, immediately generates back pressure when the drill pipe, twisted clockwise, releases its elastic torsional force and resets. This back pressure counteracts and absorbs the torsional force of the drill pipe's elastic reset, thus preventing the power head motor from stalling and reversing. Furthermore, by adding a replenishment oil circuit, when the power head motor is passively reversed due to the release of the drill pipe's elastic torsional force, the system's return oil promptly enters the reverse port through the replenishment oil circuit, preventing the power head motor from sucking in cavitation. This design, through the back pressure control of the balance valve assembly and the synergistic effect of the replenishment oil circuit, solves the problems of motor reversal and cavitation caused by the drill pipe's elastic reset, improving system safety and equipment lifespan. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the overall structure of the rotary drilling rig in the embodiments of this application.

[0021] Figure 2 A schematic diagram of drilling to transmit torque to the drill pipe.

[0022] Figure 3 This is a front view of the drill bit cutting and drilling process.

[0023] Figure 4 This is a top view of the drilling tool cutting and drilling process.

[0024] Figure 5 Front view of drill pipe torsional force release.

[0025] Figure 6 A top view showing the release of torsional forces on the drill pipe.

[0026] Figure 7 This is a hydraulic schematic diagram of the hydraulic control system of the rotary drilling rig in the embodiments of this application.

[0027] Figure 8 for Figure 7 Connection diagram of the central balancing valve assembly.

[0028] in:

[0029] 1-Main chassis, 2-Power head, 3-Drill pipe, 4-Drilling tools;

[0030] 10-Power head motor, 20-Forward rotation port oil circuit, 30-Reverse rotation port oil circuit, 40-Oil tank, 50-Balance valve assembly, 501-Relief valve, 5011-Control oil port, 502-Throttle valve, 503-Pressure stabilizing check valve, 504-Forward rotation conduction valve, 60-Maintenance oil circuit, 601-Maintenance check valve, 70-Return oil back pressure valve, 80-Maintenance accumulator, 90-Directional control valve. Detailed Implementation

[0031] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0032] To enable those skilled in the art to better understand the present application, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] Please see Figure 7 and Figure 8 , Figure 7 This is a hydraulic schematic diagram of the hydraulic control system of the rotary drilling rig in the embodiments of this application. Figure 8 for Figure 7 Connection diagram of the central balancing valve assembly.

[0034] The hydraulic control system for rotary drilling rigs provided in this application includes a power head motor 10 for driving the drill rod 3 to rotate in both directions. The power head motor 10 is provided with a forward rotation port A and a reverse rotation port B. The forward rotation port A is connected to a forward rotation port oil circuit 20, and the reverse rotation port B is connected to a reverse rotation port oil circuit 30.

[0035] Oil enters through port A (forward rotation) and exits through port B (reverse rotation). When the power head motor 10 rotates forward, oil enters through port B (reverse rotation) and exits through port A (forward rotation). When the power head motor 10 rotates in reverse, the hydraulic oil in the forward rotation port oil circuit 20 flows to the oil tank 40 through the return port T.

[0036] Furthermore, the hydraulic control system of the rotary drilling rig also includes a balance valve assembly 50 and a replenishing oil circuit 60. The balance valve assembly 50 is located in the forward rotation port oil circuit 20 and is used to generate pressure when the drill rod 3 releases its elastic torsional force to resist the drill rod 3 from resetting. The replenishing oil circuit 60 is connected to the return port T and the reverse rotation port oil circuit 30, and is used to replenish the hydraulic oil from the return port T to the reverse rotation port B to prevent the power head motor 10 from drawing in cavitation.

[0037] It should be noted that at the instant the power head motor 10 reverses and starts, and at the instant the drill pipe 3 elastically resets, the balance valve assembly 50 forms a back pressure resistance in the return oil circuit. This effectively counteracts the reset force of the drill pipe 3, slows down the elastic reset speed of the drill pipe 3, and prevents the power head motor 10 from stalling and reversing due to sudden unloading. At the same time, the reverse port B requires a large amount of oil replenishment, which can be provided in a short time using the system's return oil.

[0038] This configuration, by adding a balance valve assembly 50 to the forward rotation port oil passage 20 of the power head motor 10, ensures that when the clockwise twisted drill pipe 3 releases its elastic torsional force and resets, the balance valve assembly 50 immediately generates back pressure to counteract and absorb the torsional force of the drill pipe 3's elastic reset, thereby preventing the power head motor 10 from stalling and reversing. Furthermore, by adding a replenishing oil passage 60, when the power head motor 10 is passively reversed due to the release of the drill pipe 3's elastic torsional force, the system return oil promptly enters the reverse port B through the replenishing oil passage 60, effectively preventing the power head motor 10 from sucking in cavitation. Cavitation can lead to cavitation, poor lubrication, and component damage; the replenishing oil passage 60 significantly reduces these risks.

[0039] In other words, the hydraulic control system of the rotary drilling rig provided in this application uses the back pressure generated by the balance valve group 50 to absorb the torsional force released when the telescopic drill rod 3 of the rotary drilling rig reverses, thereby eliminating the reverse stall phenomenon of the rotary drilling rig power head motor 10. Furthermore, by using the low-pressure return oil of the system to replenish oil to the reverse port B of the passively reversed power head motor 10 in a timely manner, the cavitation phenomenon of the rotary drilling rig power head motor 10 is eliminated.

[0040] This design, through the back pressure control of the balance valve group 50 and the synergistic effect of the oil replenishment circuit 60, solves the problems of motor reversal and air suction caused by the elastic reset of the drill pipe 3, thereby improving system safety and equipment service life.

[0041] Of course, depending on actual needs, the number of the power head motor 10 and the balance valve group 50 used to control the drill pipe 3 are both two sets.

[0042] In some embodiments, the balance valve assembly 50 includes an overflow valve 501, which is disposed in the forward rotation port oil passage 20 and is used to open when the pressure in the forward rotation port oil passage 20 reaches a set threshold.

[0043] In this way, when drill pipe 3 releases energy due to elastic deformation, the pressure in the forward rotation port oil circuit 20 rises sharply. The relief valve 501 opens when it reaches a set threshold. The relief valve 501 generates back pressure in the forward rotation port oil circuit 20 through throttling damping to counteract the reset torque of drill pipe 3, thereby preventing the motor from stalling or reversing due to sudden load changes. Simultaneously, the rapid response characteristic of the relief valve 501 can promptly regulate pressure fluctuations, ensuring stable motor speed and reducing damage to the transmission system from hydraulic shocks.

[0044] In addition, by adjusting the set pressure of the overflow valve 501, it can be adapted to different working conditions (such as different drill pipe materials or formation hardness), thus improving the system's flexibility.

[0045] In some embodiments, the overflow valve 501 is provided with a control port 5011, which is connected to the reverse port oil passage 30, so that the overflow valve 501 opens when it receives a preset hydraulic oil signal from the reverse port oil passage 30.

[0046] On the one hand, when the reverse port oil circuit 30 generates a high-pressure oil signal, this signal is transmitted to the overflow valve 501 through the control port 5011, causing it to open rapidly. The overflow valve 501 releases some oil to the oil tank 40, generating back pressure in the forward port oil circuit 20, which directly counteracts the elastic reset torque of the drill rod 3. The generation of back pressure can prevent the motor from stalling and reversing due to sudden load changes. This is especially suitable for the scenario of releasing the elastic potential energy of the drill rod 3 when rotary drilling rigs and other equipment are operating in hard rock formations, ensuring the stability of the power head operation. On the other hand, when the power head motor 10 is in normal (active) reverse rotation, the oil pressure signal of the reverse port oil circuit 30 is transmitted to the overflow valve 501 through the control port 5011. The overflow valve 501 switches to the open state, realizing the hydraulic oil flow in the reverse port oil circuit 30, which is conducive to realizing the normal (active) reverse rotation process of the power head motor 10.

[0047] It should be noted that the power head motor 10 can rotate normally (actively) in reverse to allow the drill bit to detach from the rock or soil layer and unlock the drill rod 3, thus facilitating subsequent rod lifting operations.

[0048] In some embodiments, a throttle valve 502 and a pressure-stabilizing check valve 503 connected in parallel with the throttle valve 502 are provided on the oil line between the control oil port 5011 and the reverse oil line 30.

[0049] When the oil flows from the reverse port 30 to the control port 5011, the pressure-stabilizing check valve 503 closes due to reverse pressure, allowing the oil to flow only through the throttle valve 502. At this time, the throttle valve 502 reduces the cross-sectional area of ​​the flow channel, generating a throttling damping effect. This slows down the oil flow rate, prevents a sudden increase in oil pressure at the reverse port B, absorbs hydraulic shock energy, reduces pipeline vibration and noise, and prevents the motor from stalling and reversing due to sudden load changes.

[0050] When the oil needs to flow from control port 5011 to reverse port B (e.g., when the system actively drives the motor to reverse), the pressure-regulating check valve 503 opens in the forward direction, allowing the oil to flow directly through its low-resistance channel with almost no pressure drop. This ensures rapid execution of the reverse command and avoids unnecessary energy consumption by the throttle valve 502 during forward operation. During non-operational phases, the reverse sealing characteristic of the pressure-regulating check valve 503 prevents oil from flowing back from the reverse port oil circuit 30 to the control port 5011, preventing pressure leakage in the control oil circuit and ensuring the reliability of the control signal.

[0051] In some embodiments, the balance valve assembly 50 further includes a forward rotation valve 504, which is connected in parallel with the relief valve 501. The forward rotation valve 504 is used to supply hydraulic oil through the forward rotation port oil passage 20 into the forward rotation port A to realize the forward rotation of the power head motor 10.

[0052] Of course, depending on actual needs, the forward rotation valve 504 is a one-way valve, used to ensure forward operation efficiency and reverse locking safety. Specifically, when the power head motor 10 rotates forward, the forward rotation valve 504 opens, and the oil passes through with extremely low resistance, which facilitates the system to smoothly execute the forward rotation action of the power head motor 10.

[0053] In some embodiments, the replenishing oil circuit 60 is provided with a replenishing oil check valve 601, and the conduction direction of the replenishing oil check valve 601 is from the return oil port T to the reverse oil circuit 30.

[0054] In this way, the system return oil enters the reverse port B of the power head motor 10 in time through the replenishment check valve 601, thus preventing the power head motor 10 from sucking in air.

[0055] In some embodiments, a return back pressure valve 70 is provided on the oil line between the replenishment oil line 60 and the oil tank 40. The return back pressure valve 70 is used to generate pressure so that the hydraulic oil at the return port T is replenished into the reverse port B through the replenishment check valve 601.

[0056] The system return oil flows back to the hydraulic oil tank 40 through the return oil back pressure valve 70. The return oil back pressure valve 70 generates a certain low back pressure in the system return oil. When the power head motor 10 is passively reversed, the system return oil enters the reverse port B of the power head motor 10 in time through the replenishment check valve 601, thus preventing the power head motor 10 from sucking in air.

[0057] In some embodiments, the hydraulic control system of the rotary drilling rig further includes a replenishing accumulator 80, which is connected to the replenishing oil circuit 60. The replenishing accumulator 80 is used to release the stored hydraulic oil into the replenishing oil circuit 60 when the power head motor 10 is passively reversed.

[0058] The low-pressure oil stored in the accumulator 80 will also release a large amount of pressure oil in time when the power head motor 10 is passively reversed, and replenish the reverse port B of the power head motor 10, thus preventing the power head motor 10 from sucking in air.

[0059] In this way, by utilizing the low-pressure return oil of the system and the oil stored in the accumulator 80, oil is promptly replenished to the reverse port B of the passively reversed power head motor 10, thus eliminating the air suction phenomenon of the rotary drilling rig's power head motor 10.

[0060] Using the above setup, at the moment the power head motor 10 reverses and starts, and at the moment the twisted drill rod 3 elastically resets, the balance valve group 50 forms a back pressure resistance in the system's return oil circuit, which can slow down the speed of the drill rod 3's elastic reset. At the same time, the reverse port B requires a large amount of oil replenishment. By using the return oil back pressure (hydraulic oil from the reversing valve 90) + the auxiliary oil replenishment accumulator 80, sufficient replenishment can be provided in a short time.

[0061] In some embodiments, the hydraulic control system of the rotary drilling rig further includes a pressure sensor and a controller. The pressure sensor is located in the forward rotation port oil circuit 20 and is used to detect the pressure in the forward rotation port oil circuit 20. The controller is communicatively connected to the pressure sensor and the balance valve assembly 50 and is used to control the opening pressure of the balance valve assembly 50 according to the pressure signal detected by the pressure sensor.

[0062] Understandably, the pressure sensor monitors the pressure changes in the forward rotation port oil circuit 20 in real time. When the drill pipe 3 suddenly releases its reset energy due to elastic torsion, the oil pressure in the forward rotation port A will rise sharply. The controller identifies this pressure peak (e.g., exceeding a set threshold such as 35MPa) within milliseconds and immediately increases the opening pressure of the balance valve assembly 50 (e.g., by increasing the current of the solenoid coil of the relief valve 501) to generate a stronger back pressure. This back pressure directly counteracts the elastic reset torque of the drill pipe 3, preventing the power head motor 10 from stalling or reversing due to sudden load changes.

[0063] Compared to traditional mechanical balancing valves that require a preset fixed opening pressure and cannot adapt to sudden load changes, the closed-loop control system of this application dynamically adjusts the balancing valve group 50 through pressure feedback, improving the response speed by more than 50%.

[0064] It is important to note that the controller only increases the back pressure of the balance valve assembly 50 when a pressure surge is detected, maintaining a lower opening pressure (e.g., 5-10 MPa) under normal operating conditions. Compared to traditional constant back pressure designs, this reduces throttling energy loss by 15%-20%.

[0065] At the same time, when the drill pipe 3 resets, causing the motor to reverse passively, the oil pressure at the reverse port B drops sharply (possibly below 1MPa). After the controller detects the low pressure signal, it can immediately start the oil replenishment circuit 60, reduce the back pressure of the return oil back pressure valve 70, and quickly inject the oil from the oil tank 40 into the reverse port B of the power head motor 10. The oil replenishment circuit 60 can replenish the flow gap within 100ms, avoid the formation of a vacuum on the low-pressure side, and eliminate the risk of cavitation.

[0066] In addition, the controller can also determine the current geological condition (hard rock: dP / dt > 10MPa / s; soft soil: dP / dt < 2MPa / s) by analyzing the pressure change curve (such as the pressure rise rate dP / dt). Based on this, it can automatically switch the control strategy of the balance valve group 50: a high back pressure mode (such as 30MPa) is used for hard rock conditions, and a low back pressure mode (such as 10MPa) is used for soft soil conditions.

[0067] The rotary drilling rig provided in this application includes the hydraulic control system of the rotary drilling rig described in the above specific embodiments; other parts of the rotary drilling rig can be referred to in related technologies, and will not be elaborated here.

[0068] It should be noted that in this specification, relational terms such as first and second are used only to distinguish one entity from several other entities, and do not necessarily require or imply any such actual relationship or order between these entities.

[0069] The hydraulic control system for the rotary drilling rig and the rotary drilling rig provided in this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are only for the purpose of helping to understand the solution and core ideas of this application. It should be noted that those skilled in the art can make several improvements and modifications to this application without departing from the principles of this application, and these improvements and modifications also fall within the protection scope of this application.

Claims

1. A hydraulic control system for a rotary drilling rig, comprising a power head motor for driving the drill rod to rotate forward and backward, the power head motor having a forward rotation port and a reverse rotation port, the forward rotation port being connected to a forward rotation port oil circuit, and the reverse rotation port being connected to a reverse rotation port oil circuit, wherein when the power head motor reverses, the hydraulic oil in the forward rotation port oil circuit flows to the oil tank through the return port, characterized in that, The hydraulic control system of the rotary drilling rig also includes: A balance valve assembly, located in the forward rotation port oil circuit, is used to generate pressure when the drill pipe releases its elastic torsional force to resist the drill pipe's reset. The oil replenishment circuit is connected to the oil return port and the oil reversing port, and is used to replenish the hydraulic oil from the oil return port to the oil reversing port to prevent the power head motor from sucking in cavitation.

2. The hydraulic control system for rotary drilling rigs as described in claim 1, characterized in that, The balance valve assembly includes an overflow valve, which is located in the forward rotation port oil circuit and is used to open when the pressure in the forward rotation port oil circuit reaches a set threshold.

3. The hydraulic control system for rotary drilling rigs as described in claim 2, characterized in that, The overflow valve is provided with a control port, which is connected to the reverse port oil circuit, so that the overflow valve opens when it receives a preset hydraulic oil signal from the reverse port oil circuit.

4. The hydraulic control system for rotary drilling rigs as described in claim 3, characterized in that, A throttle valve and a pressure-stabilizing check valve are provided on the oil line between the control oil port and the reverse oil line.

5. The hydraulic control system for rotary drilling rigs as described in claim 2, characterized in that, The balance valve assembly also includes a forward rotation valve, which is connected in parallel with the relief valve. The forward rotation valve is used to supply hydraulic oil through the forward rotation port oil circuit to the forward rotation port so as to realize the forward rotation of the power head motor.

6. The hydraulic control system for a rotary drilling rig as described in any one of claims 1-5, characterized in that, The replenishing oil line is equipped with a replenishing check valve, and the conduction direction of the replenishing check valve is from the return oil port to the reverse oil port.

7. The hydraulic control system for a rotary drilling rig as described in claim 6, characterized in that, A return oil back pressure valve is provided on the oil line between the replenishment oil line and the oil tank. The return oil back pressure valve is used to generate pressure so that the hydraulic oil at the return oil port is replenished into the reverse port through the replenishment oil check valve.

8. The hydraulic control system for a rotary drilling rig as described in any one of claims 1-5, characterized in that, The hydraulic control system of the rotary drilling rig also includes a replenishing accumulator, which is connected to the replenishing oil circuit. The replenishing accumulator is used to release the stored hydraulic oil into the replenishing oil circuit when the power head motor is passively reversed.

9. The hydraulic control system for a rotary drilling rig as described in any one of claims 1-5, characterized in that, The hydraulic control system of the rotary drilling rig also includes a pressure sensor and a controller. The pressure sensor is located in the forward rotation port oil circuit and is used to detect the pressure in the forward rotation port oil circuit. The controller is communicatively connected to the pressure sensor and the balance valve group and is used to control the opening pressure of the balance valve group according to the pressure signal detected by the pressure sensor.

10. A rotary drilling rig, characterized in that, Includes the hydraulic control system for rotary drilling rigs as described in any one of claims 1-9.

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