Power head torque release device, control method and engineering machinery

Abstract

The invention relates to the technical field of hydraulic control systems, in particular to a power head torque release device, a control method and engineering machinery. The power head torque release device comprises a main pump and a power head motor, and is characterized by further comprising an auxiliary valve group, and a C1 port and a C2 port of the auxiliary valve group are connected to a first main oil way and a second main oil way respectively; the auxiliary valve group comprises a shuttle valve, a pressure reducing valve, an electric proportional pressure reducing valve and a flow control valve; a port A3 and a port B3 of the flow control valve are respectively connected with the port C1 and the port C2; the auxiliary valve group has a first state and a second state; and the pressure of the k port can be controlled by controlling the control current of the electric proportional pressure reducing valve so as to control the opening degree of the flow control valve. Therefore, torque release of the power head is stable and controllable under the condition that a main oil way is not changed, and the problems that in the prior art, the torque release process before rod replacement of a drilling machine is large in operation difficulty, a motor is prone to being damaged, and construction efficiency is affected are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of hydraulic control systems, and in particular to a power head torque release device, a control method and engineering machinery. Background Art

[0002] With the increasing number of large-scale natural gas and oil pipeline projects, large-diameter, long-distance projects are increasingly being constructed using trenchless horizontal directional drilling (HDD). The requirements for large HDD construction are becoming increasingly stringent. In recent years, the number of projects involving lengths exceeding 1,000 meters and pipe diameters exceeding 1 meter has been increasing.

[0003] Due to the large diameter and long length of the pipe, the construction torque and push-pull forces increase significantly. When the hole diameter is expanded, the drill head drags the drill pipe backward. When it reaches the rear rod change position, the driller (the operator of the drill rig) needs to remove the drill pipe. At this time, the driller will first loosen the power head rotary handle (used to control the rotation of the power head motor) to maintain the drill pipe torque by relying on the hydraulic system's inherent locking function. However, the driller needs to release this torque before removing the drill pipe. The usual operation method is for the driller to reverse the power head rotary handle to slowly release the system torque. However, this operation is difficult to release due to the poor controllability of the handle, unstable dead zone, and load fluctuations. It usually takes a long time, especially for novice drillers. During operation, the torque release process is often uncontrollable, causing the motor to overspeed and damage, seriously affecting construction efficiency and poor safety. Summary of the Invention

[0004] The purpose of the present invention is to provide a power head torque release device, control method and engineering machinery. By setting an auxiliary valve group, the electric proportional pressure reducing valve shall not be energized in the normal working mode, and the auxiliary valve group does not participate in the oil circuit control. In the torque release mode, the electric proportional pressure reducing valve shall be energized. By controlling the current of the electric proportional pressure reducing valve, the speed and speed change rate threshold of the power head motor can be controlled to achieve the purpose of stable and controllable torque release of the power head.

[0005] In order to achieve the above purpose, the present invention adopts the following technical solutions: In a first aspect, the present invention provides a power head torque release device, comprising a main pump and a power head motor, wherein a reverse oil port of the power head motor is connected to port A of the main pump via a first main oil circuit, and a forward oil port of the power head motor is connected to port B of the main pump via a second main oil circuit; characterized in that it further comprises: An auxiliary valve group, wherein ports C1 and C2 of the auxiliary valve group are connected to the first main oil circuit and the second main oil circuit respectively; the auxiliary valve group includes a shuttle valve, a pressure reducing valve, an electric proportional pressure reducing valve and a flow control valve; ports A3 and B3 of the flow control valve are connected to ports C1 and C2 respectively; The auxiliary valve group has a first state and a second state; in normal working mode, the main pump outputs hydraulic oil, the auxiliary valve body is in the first state, the electric proportional pressure reducing valve is not energized, and the A3 port and B3 port of the flow control valve are cut off; in torque release mode, the main pump is in a zero output state, the auxiliary valve body is in the second state, the electric proportional pressure reducing valve is energized, and the hydraulic oil flows in from the C1 port or the C2 port and then passes through the shuttle valve, the pressure reducing valve and the electric proportional pressure reducing valve to act on the k port of the flow control valve, so that the A3 port and the B3 port of the flow control valve are conductive; by controlling the control current of the electric proportional pressure reducing valve, the pressure of the k port can be controlled to control the opening degree of the flow control valve.

[0006] Optionally, the a port and b port of the shuttle valve are connected to the C1 port and C2 port respectively, and the c port of the shuttle valve is connected to the P1 port of the pressure reducing valve; the A1 port of the pressure reducing valve is connected to the P2 port of the electric proportional pressure reducing valve, and the P2 port of the electric proportional pressure reducing valve is connected to the k port of the flow control valve.

[0007] Optionally, the electric proportional pressure reducing valve is a three-way pressure reducing valve; the left end of the electric proportional pressure reducing valve is provided with a first return spring and is connected to the A2 port, the right end of the electric proportional pressure reducing valve is the electric control end, and the T port of the electric proportional pressure reducing valve is connected to the oil tank through the L port of the auxiliary valve group.

[0008] Optionally, the flow control valve includes a reversing valve, and the reversing valve includes a left position and a right position; the left end of the reversing valve is connected to the K port, and the right end is provided with a second return spring; When the electric proportional pressure reducing valve is not energized, the K port is pressureless, the reversing valve is in the right position, the oil inlet and oil outlet of the reversing valve are cut off, and the A3 port and B3 port of the flow control valve are cut off; When the electric proportional pressure reducing valve is energized, the hydraulic oil acts on the k port, the reversing valve is switched to the left position, and the A3 port and the B3 port of the flow control valve are connected.

[0009] Optionally, the flow control valve further includes a relief valve, the oil inlet of the relief valve is connected to the A3 port and the B3 oil port, and the oil outlet of the relief valve is connected to the oil inlet of the reversing valve.

[0010] In a second aspect, the present invention provides a method for controlling a torque release device of a power head, which is performed using the torque release device of the power head, and comprises the following steps: Step S1: Check whether the control current of the main pump is 0; if it is 0, go directly to step 2; if not, adjust the control current of the main pump to 0 and then go to step 2; Step S2: The main pump maintains a zero output state, obtains the current displacement of the power head motor, calculates the required control current according to the motor speed calculation formula, and inversely calculates the control current change rate according to the angular acceleration calculation formula; Step S3: The controller outputs the calculated control current and the control current change rate to control the motor speed and angular acceleration to be lower than a preset safety threshold.

[0011] Optionally, the motor speed calculation formula is: n=Q / V=KI / V, Among them, Q is the flow rate passing through the flow control valve, n is the motor speed, K is the valve characteristic slope, I is the control current of the electric proportional pressure reducing valve 8, and V is the current displacement of the motor.

[0012] Optionally, the angular acceleration calculation formula is: α=Δn / Δt=ΔQ / (V×Δt)=KΔI / (V×Δt), Wherein Δn is the speed increment, Δt is the time change, and ΔI is the control current increment of the electric proportional pressure reducing valve 8.

[0013] Optionally, the calculation formula for the current displacement of the motor is: V = V0 × (i2-i) / (i2-i1); Where V is the current displacement of the motor, V0 is the maximum displacement of the motor, i is the current value of the motor displacement control current, i1 is the starting value of the motor displacement control current, and i2 is the final value of the motor displacement control current.

[0014] In a third aspect, the present invention provides an engineering machine, including the power head torque release device Compared with the prior art, the present invention has the following beneficial effects: The present invention enables the auxiliary valve group to operate in the first state, blocking ports A3 and B3, allowing independent control of the main oil circuit, normal operation of the power head motor, and independent operation of the drilling rig. The auxiliary valve group's second state connects ports A3 and B3, and by controlling the control current of the electro-proportional pressure reducing valve, the pressure at port K can be controlled to control the opening of the flow control valve. This ensures stable and controllable torque release from the power head while maintaining the main oil circuit. This solves the existing problem of difficult torque release before drilling rig rod change, which can easily lead to motor damage and thus affect construction efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is the hydraulic principle diagram of the present invention; Figure 2 This is a schematic diagram of the auxiliary valve group of the present invention; Figure 3is a flow chart of the control method of the present invention; Figure 4 It is a logic control block diagram of the present invention; Figure 5 It is the curve of the power head motor speed changing with the reversing valve current; Figure 6 It is a curve showing the change of the current displacement of the power head motor as the motor coil control current changes.

[0016] In the figure: 1. Main pump, 2. Auxiliary valve group, 3. Power head motor 1, 4. Power head motor 2, 5. Pressure sensor 1, 6. Pressure sensor 2, 7. Speed ​​sensor; 8. Electric proportional pressure reducing valve; 9. Flow control valve; 10. Shuttle valve; 11. Pressure reducing valve. DETAILED DESCRIPTION

[0017] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more. In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0018] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Example 1

[0019] Combine Figure 1-Figure 2,,This embodiment provides a power head torque release device, including a main pump 1 and a power head motor, the reverse oil port of the power head motor is connected to the oil outlet A of the main pump 1 through a first main oil circuit, and the forward oil port of the power head motor is connected to the oil outlet B of the main pump 1 through a second main oil circuit; in a specific embodiment, there are two power head motors, namely power head motor 1 3 and power head motor 2 4.

[0020] The power head torque release device also includes an auxiliary valve group 2, whose C1 and C2 ports are connected to the first and second main oil circuits, respectively. The auxiliary valve group 2 includes a shuttle valve 10, a pressure reducing valve 11, an electric proportional pressure reducing valve 8, and a flow control valve 9. The electric proportional pressure reducing valve 8, flow control valve 9, shuttle valve 10, and pressure reducing valve 11 are all standard components and are installed on the manifold. The working oil ports A3 and B3 of the flow control valve 9 are connected to the C1 and C2 ports, respectively. The flow control valve 9 has its own pressure compensator, which ensures that the flow through the flow control valve 9 is related only to the valve opening itself and not to the system pressure difference, resulting in a linear control curve.

[0021] The auxiliary valve group 2 has a first state and a second state.

[0022] The torque release device for the power head has two control modes: normal operation mode and torque release mode. Both control modes are input via a switch or display. The controller recognizes the switch or display input and controls the operation of the main pump 1 and the auxiliary valve assembly 2. This embodiment automatically determines the current condition based on the switch or display input, notifies the user via the display, and then controls the operation of the auxiliary valve assembly 2 and the main pump 1, demonstrating interactive automatic control.

[0023] In normal operation mode, the main pump 1 delivers hydraulic oil, the auxiliary valve body is in the first state, the coil of the electric proportional pressure reducing valve 8 is de-energized, and the working oil ports A3 and B3 of the flow control valve 9 are blocked, that is, the oil circuit is disconnected. At this time, the main oil circuit is independently controlled and has nothing to do with the auxiliary valve group 2. This mode is used for independent operation of the drilling rig.

[0024] In torque release mode, the main pump 1 is in a neutral, zero-output state, the auxiliary valve body is in the second state, and the coil of the electric proportional pressure-reducing valve 8 is energized. Hydraulic oil flows in through ports C1 or C2, passes through the shuttle valve 10, the pressure-reducing valve 11, and the electric proportional pressure-reducing valve 8, and acts on the control port k of the flow control valve 9, thereby connecting the working ports A3 and B3 of the flow control valve 9. By controlling the control current of the electric proportional pressure-reducing valve 8, the pressure at port k can be controlled, thereby controlling the opening degree of the flow control valve 9.

[0025] Specifically, the oil inlet a and the oil inlet b of the shuttle valve 10 are connected to the C1 and C2 ports respectively, and the oil outlet c of the shuttle valve 10 is connected to the P1 port of the pressure reducing valve 11; the A1 port of the pressure reducing valve 11 is connected to the P2 port of the electric proportional pressure reducing valve 8, and the P2 port of the electric proportional pressure reducing valve 8 is connected to the k port of the flow control valve 9.

[0026] The electric proportional pressure reducing valve 8 is a three-way pressure reducing valve 11; the left end of the electric proportional pressure reducing valve 8 is provided with a first return spring and is connected to the A2 port, the right end of the electric proportional pressure reducing valve 8 is the electric control end, and the T port of the electric proportional pressure reducing valve 8 is connected to the oil tank through the L port of the auxiliary valve group 2. When the electric proportional pressure reducing valve 8 is not energized, under the action of the first return spring, the P2 port and the A2 port are not connected. When the electric proportional pressure reducing valve 8 is energized, the P2 port and the A2 port are connected, and the A2 port outputs hydraulic oil. If the pressure at the A2 port is greater than the preset pressure, the pressure at the A2 port acts on the left end of the electric proportional pressure reducing valve 8, and the P2 port and the A2 port of the electric proportional pressure reducing valve 8 are cut off to protect the oil circuit.

[0027] The flow control valve 9 includes a reversing valve, which includes a left position and a right position; the left end of the reversing valve is connected to the k port, and the right end is provided with a second return spring; when the electric proportional pressure reducing valve 8 is not energized, the k port is pressureless, the reversing valve is in the right position, the oil inlet and oil outlet of the reversing valve are cut off, and the A3 port and B3 port of the flow control valve 9 are cut off; when the electric proportional pressure reducing valve 8 is energized, the hydraulic oil acts on the k port, the reversing valve is switched to the left position, and the A3 port and B3 port of the flow control valve 9 are connected.

[0028] The flow control valve 9 also includes a relief valve, the oil inlet of which is connected to the A3 port and the B3 port, and the oil outlet of which is connected to the oil inlet of the reversing valve. The relief valve is used to cut off the A3 port and the B3 port to protect the oil circuit when the pressure at the A3 port or the B3 port exceeds a preset threshold.

[0029] The oil flow process in the auxiliary valve group 2 is explained as follows: Step 1. Connect the oil port a or oil port b of the shuttle valve 10 to the oil port c, and the oil port c outputs to the oil inlet P1 of the pressure reducing valve 11. The working oil port A1 of the pressure reducing valve 11 outputs to the oil port P2 of the electric proportional pressure reducing valve 8; Step 2: Control the change of the control current of the electric proportional pressure reducing valve 8 according to the corresponding control method; Step 3: The control current of the electric proportional pressure reducing valve 8 changes so that the pressure at port A2 changes. Different control current values ​​correspond to different pressures at port A2. Step 4: The pressure at port A2 acts on the control oil port K, which is the control end, to switch the flow control valve 9 to the right position. Different pressures at port K correspond to different opening degrees of the flow control valve 9. Step 5: After the transposition, the A3 port and the B3 port of the flow control valve 9 are connected. The degree of connection depends on the opening degree of the flow control valve 9 in step 4. In step 6 and step 5, the greater the degree of connectivity between port A3 and port B3, the greater the flow of hydraulic oil between port A3 and port B3. Since the pressures at port A3 and port B3 are not equal (the drill pipe counter-torque acts on the power head), the corresponding motor rotational angular velocity is greater. Step 7. Simultaneously with Step 3, changes in the control current of the electric proportional pressure reducing valve 8 cause corresponding changes in port A2. The faster the control current changes, the faster the pressure at port A2 changes. Consequently, the faster the spool of the corresponding flow control valve 9 moves, the faster the connectivity between ports A3 and B3 changes. The greater the hydraulic oil flow between ports A3 and B3, the greater the corresponding motor angular acceleration. The control objective of this embodiment is to ensure that both the motor speed and the speed change rate do not exceed a set threshold.

[0030] In addition, the torque release device in this embodiment can be used in both open hydraulic systems and closed hydraulic systems. The control principles are similar, and the present invention takes a closed hydraulic system as an embodiment. Example 2

[0031] Combine Figure 3-Figure 5 This embodiment provides a control method, which is performed using the power head torque release device described in Example 1, and includes the following steps: Step S1: Detect whether the control current of the main pump 1 is 0; Step S2: If it is 0, go directly to step 2; if it is not 0, remind the user to adjust the control current of the main pump 1 to 0 and then go to step 2; Step S3: Detecting the pressure values ​​of pressure sensor 1 5 and pressure sensor 2 6 and the control current of the motor displacement respectively; Step S4: determining the desired speed threshold n1 of the motor; Step S5: Main pump 1 maintains a zero output state, obtains the current displacement of the power head motor, and calculates the theoretical motor speed; The calculation formula for the current displacement of the motor is: V = V0 × (i2-i) / (i2-i1); Where V is the current displacement of the motor, V0 is the maximum displacement of the motor, i is the current value of the motor displacement control current, i1 is the starting value of the motor displacement control current, and i2 is the final value of the motor displacement control current.

[0032] Step S6: Make the theoretical motor speed n0 less than the desired speed threshold n1; Step S7: The motor speed n is monitored in real time by the speed sensor 7, and the control current of the electric proportional pressure reducing valve 8 is adjusted in real time to make n less than the desired speed threshold n1.

[0033] In step S7, the required control current of the electric proportional pressure reducing valve 8 is calculated according to the motor speed calculation formula, and the control current change rate of the electric proportional pressure reducing valve 8 is inversely calculated according to the angular acceleration calculation formula; the controller outputs the calculated control current and the control current change rate of the electric proportional pressure reducing valve 8 to control the motor speed and angular acceleration to be lower than the preset safety threshold.

[0034] In a specific embodiment, the motor speed calculation formula is: n=Q / V=KI / V, Among them, Q is the flow rate passing through the flow control valve 9, n is the motor speed, K is the valve characteristic slope, I is the control current of the electric proportional pressure reducing valve 8, and V is the current displacement of the motor.

[0035] In another specific embodiment, the angular acceleration calculation formula is: α=Δn / Δt=ΔQ / (V×Δt)=KΔI / (V×Δt), Wherein Δn is the speed increment, Δt is the time change, and ΔI is the control current increment of the electric proportional pressure reducing valve 8.

[0036] The calculation formula for the current displacement of the motor is: V = V0 × (i2-i) / (i2-i1); Where V is the current displacement of the motor, V0 is the maximum displacement of the motor, i is the current value of the motor displacement control current, i1 is the starting value of the motor displacement control current, and i2 is the final value of the motor displacement control current.

[0037] The pressure sensor 1 5 and the pressure sensor 2 6 are respectively connected to the M1 port and the M2 port of the auxiliary valve group 2. The pressure values ​​detected by the pressure sensor 1 5 and the pressure sensor 2 6 are used for real-time detection in the normal working mode and for determining the release moment in the torque release mode. When the pressure value drops to the preset value, it is determined that the torque release is completed. Example 3

[0038] This embodiment provides an engineering machine including the power head torque release device. The engineering machine includes a drilling rig, which is a machine equipped with an open hydraulic system or a closed hydraulic system. The present invention uses a trenchless horizontal directional drilling rig as an embodiment.

[0039] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A power head torque release device, comprising a main pump (1) and a power head motor, wherein the reverse oil port of the power head motor is connected to the A port of the main pump (1) through a first main oil circuit, and the forward oil port of the power head motor is connected to the B port of the main pump (1) through a second main oil circuit; characterized in that: Also includes: an auxiliary valve group (2), wherein the C1 port and the C2 port of the auxiliary valve group (2) are respectively connected to the first main oil circuit and the second main oil circuit; the auxiliary valve group (2) comprises a shuttle valve (10), a pressure reducing valve (11), an electric proportional pressure reducing valve (8) and a flow control valve (9); the A3 port and the B3 port of the flow control valve (9) are respectively connected to the C1 port and the C2 port; The auxiliary valve group (2) has a first state and a second state; in a normal working mode, the main pump (1) outputs hydraulic oil, the auxiliary valve body is in the first state, the electric proportional pressure reducing valve (8) is not energized, and the A3 port and the B3 port of the flow control valve (9) are cut off; In the torque release mode, the main pump (1) is in a zero output state, the auxiliary valve body is in a second state, the electric proportional pressure reducing valve (8) is energized, and hydraulic oil flows in from the C1 port or the C2 port and passes through the shuttle valve (10), the pressure reducing valve (11) and the electric proportional pressure reducing valve (8) to act on the k port of the flow control valve (9), so that the A3 port and the B3 port of the flow control valve (9) are connected; by controlling the control current of the electric proportional pressure reducing valve (8), the pressure at the k port can be controlled to control the opening degree of the flow control valve (9).

2. The power head torque release device according to claim 1, characterized in that: The a port and the b port of the shuttle valve (10) are connected to the C1 port and the C2 port respectively; the c port of the shuttle valve (10) is connected to the P1 port of the pressure reducing valve (11); the A1 port of the pressure reducing valve (11) is connected to the P2 port of the electric proportional pressure reducing valve (8); and the P2 port of the electric proportional pressure reducing valve (8) is connected to the k port of the flow control valve (9).

3. The power head torque release device according to claim 1, characterized in that: The electric proportional pressure reducing valve (8) is a three-way pressure reducing valve (11); the left end of the electric proportional pressure reducing valve (8) is provided with a first return spring and is connected to the A2 port, the right end of the electric proportional pressure reducing valve (8) is an electric control end, and the T port of the electric proportional pressure reducing valve (8) is connected to the oil tank via the L port of the auxiliary valve group (2).

4. The power head torque release device according to claim 3, characterized in that: The flow control valve (9) comprises a reversing valve, the reversing valve comprising a left position and a right position; the reversing valve has a left end connected to the k port and a second return spring is provided at the right end; When the electric proportional pressure reducing valve (8) is not energized, there is no pressure at the k port, the reversing valve is in the right position, the oil inlet and oil outlet of the reversing valve are cut off, and the A3 port and B3 port of the flow control valve (9) are cut off; When the electric proportional pressure reducing valve (8) is energized, hydraulic oil acts on the k port, the reversing valve is switched to the left position, and the A3 port and the B3 port of the flow control valve (9) are connected.

5. The power head torque release device according to claim 4, characterized in that: The flow control valve (9) further comprises a relief valve, wherein the oil inlet of the relief valve is connected to the A3 port and the B3 oil port, and the oil outlet of the relief valve is connected to the oil inlet of the reversing valve.

6. A control method for a torque release device of a power head, characterized in that: The method is carried out by using the torque release device of the power head according to any one of claims 1 to 5, which comprises the following steps: Step S1: Detect whether the control current of the main pump (1) is 0; if it is 0, directly proceed to step 2; if it is not 0, adjust the control current of the main pump (1) to 0 and then proceed to step 2; Step S2: the main pump (1) maintains a zero output state, obtains the current displacement of the power head motor, calculates the required control current according to the motor speed calculation formula, and reversely calculates the control current change rate according to the angular acceleration calculation formula; Step S3: The controller outputs the calculated control current and the control current change rate to control the motor speed and angular acceleration to be lower than a preset safety threshold.

7. The control method of the torque release device of the power head according to claim 6, characterized in that: The motor speed calculation formula is: n=Q / V=KI / V, Wherein, Q is the flow rate through the flow control valve (9), n is the motor speed, K is the valve characteristic slope, I is the control current of the electric proportional pressure reducing valve 8, and V is the current displacement of the motor.

8. The control method of the torque release device of the power head according to claim 6, characterized in that: The angular acceleration calculation formula is: α=Δn / Δt=ΔQ / (V×Δt)=KΔI / (V×Δt), Wherein Δn is the speed increment, Δt is the time change, and ΔI is the control current increment of the electric proportional pressure reducing valve 8 .

9. The control method of the torque release device of the power head according to claim 6, characterized in that: The calculation formula for the current displacement of the motor is: V = V0 × (i2-i) / (i2-i1); Where V is the current displacement of the motor, V0 is the maximum displacement of the motor, i is the current value of the motor displacement control current, i1 is the starting value of the motor displacement control current, and i2 is the final value of the motor displacement control current.

10. An engineering machine, comprising the power head torque release device according to any one of claims 1 to 5.

Images