Electro-hydraulic steering start-stop smooth control system of engineering machinery and control method thereof

Abstract

The application discloses an electro-hydraulic steering start-stop smooth control system of an engineering machine and a control method thereof in the technical field of engineering machines, and the system comprises: a steering actuator comprising a left turning oil cylinder and a right turning oil cylinder; a steering control valve connected with the left turning oil cylinder and the right turning oil cylinder and used for supplying oil to the left turning oil cylinder or the right turning oil cylinder; a steering wheel and a hydraulic steering gear, the steering wheel is connected with a control end of the hydraulic steering gear, the hydraulic steering gear is connected with a control end of the steering control valve, and the hydraulic steering gear is used for driving the steering control valve to act; a one-way valve and an electronic limit valve are further arranged on a control oil circuit between the hydraulic steering gear and the steering control valve and are used for guaranteeing steering start-stop smoothness; and a motor pump, an input end of which is connected with a hydraulic oil tank, and an output end of which is connected with the steering control valve and the hydraulic steering gear, is used for supplying oil to the steering control valve and the hydraulic steering gear. The application can significantly improve the steering operation experience of the engineering machine based on the above system and the corresponding control method.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of engineering machinery, and in particular to an electro-hydraulic steering start-stop smooth control system of engineering machinery and a control method thereof. BACKGROUND

[0002] With the transformation of engineering machinery to electronic control, intelligentization and greenization, higher requirements are put forward for the steer-by-wire system. There are generally three kinds of steering systems for engineering machinery: deflection type, hinged type and sliding type. Among them, the hinged steering vehicle refers to a vehicle whose vehicle body is composed of two or more separate frames, and the front and rear frames are relatively deflected through hydraulic or other action forms to achieve the purpose of steering, such as loaders, road rollers, land levelers and mine trucks, etc. Compared with other steering modes, hinged steering has many advantages, such as small turning radius, under the same wheelbase and track, the turning radius of hinged steering is about 80% of that of front wheel steering, and if the braking torque is reasonably utilized, the turning radius can be further reduced; the energy consumed in the steering process is low because the sliding resistance does not need to be overcome; there is no relative deflection between the wheels and the frame, and no steering drive axle is needed. These advantages promote more and more manufacturers to choose this simple and efficient steering mode for engineering vehicles. The widespread application of hinged steering engineering vehicles in construction exposes some shortcomings, among which the most influential one on safety is the poor lateral stability. Hinged steering engineering vehicles have road driving requirements in some countries and regions, and the speed is relatively high, so there are higher requirements for steering stability. The conventional flow amplification steering system is prone to have large steering impact and unstable steering when steering at a high vehicle speed. Therefore, the smoothness and safety of hinged steer-by-wire engineering vehicles are gradually valued by people. SUMMARY

[0003] The present application aims at overcoming the deficiencies in the prior art, and provides an electro-hydraulic steering start-stop smooth control system of engineering machinery and a control method thereof, which solves the technical problem of how to improve the smoothness and safety of hinged steer-by-wire engineering vehicles.

[0004] To achieve the above-mentioned purpose, the present application adopts the following technical scheme:

[0005] In a first aspect, the present application provides an electro-hydraulic steering start-stop smooth control system of engineering machinery, comprising:

[0006] a steering actuator comprising a left turning oil cylinder and a right turning oil cylinder;

[0007] a steering control valve connected to the input ends of the left turning oil cylinder and the right turning oil cylinder, for supplying oil to the left turning oil cylinder or the right turning oil cylinder;

[0008] The steering system includes a steering wheel and a hydraulic steering gear. The steering wheel is connected to the control end of the hydraulic steering gear, and the hydraulic steering gear is connected to the control end of the steering control valve to drive the steering control valve. A one-way valve and an electronic limit valve are also provided on the left turn control oil circuit and the right turn control oil circuit between the hydraulic steering gear and the steering control valve to ensure smooth steering start and stop.

[0009] An electric pump, whose input end is connected to a hydraulic oil tank and whose output end is connected to the steering control valve and the hydraulic steering gear, is used to supply oil to the steering control valve and the hydraulic steering gear.

[0010] Optionally, the steering actuator further includes a left-turn explosion-proof valve, a left-turn check valve, a right-turn explosion-proof valve, and a right-turn check valve for pressure reduction and oil replenishment. One end of the left-turn explosion-proof valve and the left-turn check valve are connected to the input end of the left-turn cylinder, and the other end is connected to the hydraulic oil tank. One end of the right-turn explosion-proof valve and the right-turn check valve are connected to the input end of the right-turn cylinder, and the other end is connected to the hydraulic oil tank.

[0011] Optionally, the steering actuator further includes an angle sensor for detecting the steering angle, the angle sensor being disposed at the hinge point between the left-turn cylinder or the right-turn cylinder and the turntable.

[0012] Optionally, the steering control valve includes a directional valve, a flow amplification valve, and a hydraulic bypass valve. The output end of the motor pump is connected to the input end of the flow amplification valve, the output end of the flow amplification valve is connected to the input end of the directional valve, and the output L end and output R end of the directional valve are respectively connected to the input ends of the left-turn cylinder and the right-turn cylinder. The hydraulic bypass valve is connected to the control end of the flow amplification valve for damping control.

[0013] Optionally, the steering control valve further includes a priority valve, the input end of which is connected to the output end of the motor pump, the output CF end of which is connected to the input ends of the flow amplification valve and the hydraulic steering gear, and the output EF end of which is connected to the hydraulic working system.

[0014] Optionally, an accumulator is also provided in the oil line connecting the motor pump and the hydraulic steering gear. The accumulator includes a one-way throttle valve and an accumulator tank. The one-way throttle valve is connected in series in the oil line connecting the motor pump and the hydraulic steering gear. The opening of the accumulator tank is connected to the oil line connecting the one-way throttle valve pump and the hydraulic steering gear. The accumulator is used to assist the hydraulic steering gear in smooth steering.

[0015] Optionally, the steering system further includes a speed sensor for detecting the steering speed of the steering wheel.

[0016] Optionally, the motor pump comprises a motor and an electric control plunger pump coaxially connected, the electric control plunger pump is used for providing oil supply power, and the motor is used for driving the electric control plunger pump to act.

[0017] In a second aspect, the present application provides a buffer control method of an electro-hydraulic steering start-stop smooth control system, which adopts the electro-hydraulic steering start-stop smooth control system, and the buffer control method comprises the following steps:

[0018] obtaining a real-time steering angle of the steering actuator;

[0019] when the steering angle enters a steering angle buffer range of the limit position, the left turning control oil path or the right turning control oil path between the hydraulic steering gear and the steering control valve is cut off through the corresponding electronic limit valve;

[0020] the steering control valve stops working, the engineering machinery is turned to the limit position under the action of inertia, the electric control plunger pump is rapidly discharged, the motor speed is slowly reduced to the standby speed, and the engineering machinery is stopped smoothly;

[0021] wherein the steering angle buffer range is , is a limit position steering angle calibration value, is a preset deviation value.

[0022] In a third aspect, the present application provides a smooth control method of an electro-hydraulic steering start-stop smooth control system, which adopts the electro-hydraulic steering start-stop smooth control system, and the smooth control method comprises the following steps:

[0023] when the steering speed of the steering wheel , the steering flow is not requested, the electric control plunger pump is in standby displacement, and the motor is in standby speed;

[0024] when the steering speed of the steering wheel , it is judged as a misoperation, the steering flow is not requested, the electric control plunger pump is in standby displacement, and the motor is in standby speed;

[0025] when the steering speed of the steering wheel , it is judged as normal steering operation, the steering flow is set as a calibration flow, the target displacement of the electric control plunger pump is calculated through a flow-displacement interpolation table, the electric control plunger pump is raised from standby displacement to the target displacement, and the motor is in standby speed;

[0026] when the steering speed of the steering wheel , it is judged as normal steering operation, the requested steering flow is calculated through a steering wheel steering speed-flow interpolation table, the target displacement of the electric control plunger pump is calculated through a flow-displacement interpolation table, the electric control plunger pump is raised from standby displacement to the target displacement, and the motor is in standby speed;

[0027] When the steering speed of the steering wheel is less than the minimum steering speed and greater than the maximum steering speed If it is determined as normal steering operation, the electric control plunger pump is raised from standby displacement to maximum displacement, the target speed of the motor is calculated through the steering wheel steering speed-motor speed interpolation table, and the motor is raised from standby speed to the target speed.

[0028] Compared with the prior art, the present application has the following beneficial effects:

[0029] The electro-hydraulic steering start-stop smooth control system and control method of the engineering machinery provided by the present application ensure smooth steering start-stop of the engineering machinery, and have certain economy and universality. On the basis of the system, the buffer control method and the smooth control method control the motor, the electric control plunger pump and the electronic limit valve L / R respectively, so as to eliminate the problems in the conventional system, such as large steering torque at start, large impact and shaking at stop, non-energy-saving of the steering system, and complicated and poor effect of the steering limit position calibration process. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 is a structural schematic diagram of the electro-hydraulic steering start-stop smooth control system of the engineering machinery provided by the embodiment of the present application;

[0031] Figure 2 is a flowchart of the buffer control method of the electro-hydraulic steering start-stop smooth control system provided by the embodiment of the present application;

[0032] Figure 3 is a flowchart of the smooth control method of the electro-hydraulic steering start-stop smooth control system provided by the embodiment of the present application;

[0033] Figure 4 is a flowchart of the limit angle calibration of the electro-hydraulic steering start-stop smooth control system provided by the embodiment of the present application;

[0034] In the figure, the following are marked:

[0035] 1, steering actuator; 1.1, angle sensor; 1.2, left turning oil cylinder; 1.3, right turning oil cylinder; 1.4, left turning explosion-proof valve; 1.5, left turning check valve; 1.6, right turning explosion-proof valve; 1.7, right turning check valve;

[0036] 2, steering control valve; 2.1, reversing valve; 2.2, flow amplification valve; 2.3, hydraulic control bypass valve; 2.4, priority valve;

[0037] 3, motor pump; 3.1, electric control plunger pump; 3.2, motor;

[0038] 4, accumulator; 4.1, check valve; 4.2, accumulator tank;

[0039] 5, controller;

[0040] 6. Steering system; 6.1. Hydraulic steering system; 6.2. Speed ​​sensor;

[0041] 7. Electronic limit valve; 7.1. Left control electronic limit valve; 7.2. Right control electronic limit valve;

[0042] 8. Check valve; 8.1. Left-controlled check valve; 8.2. Right-controlled check valve. Detailed Implementation

[0043] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0044] Example 1:

[0045] like Figure 1 As shown, this embodiment of the invention provides an electro-hydraulic steering start-stop smooth control system for engineering machinery, including a steering actuator 1, a steering control valve 2, a steering gear 6, and a motor pump 3.

[0046] The steering actuator includes a left-turn cylinder 1.2 and a right-turn cylinder 1.3, which drive the articulated steering mechanism to rotate. When the left-turn cylinder 1.2 is engaged, left turn is achieved; when the right-turn cylinder 1.3 is engaged, right turn is achieved.

[0047] The steering actuator also includes a left-turn explosion-proof valve 1.4, a left-turn check valve 1.5, a right-turn explosion-proof valve 1.6, and a right-turn check valve 1.7. One end of the left-turn explosion-proof valve 1.4 and the left-turn check valve 1.5 is connected to the input end of the left-turn cylinder 1.2, and the other end is connected to the hydraulic oil tank. One end of the right-turn explosion-proof valve 1.6 and the right-turn check valve 1.7 is connected to the input end of the right-turn cylinder 1.3, and the other end is connected to the hydraulic oil tank. The left-turn explosion-proof valve 1.4, the left-turn check valve 1.5, the right-turn explosion-proof valve 1.6, and the right-turn check valve 1.7 are used for pressure reduction and oil replenishment to ensure normal steering operation.

[0048] The steering actuator also includes an angle sensor 1.1, which is located at the hinge between the left-turn cylinder 1.2 or the right-turn cylinder 1.3 and the turntable, and is used to detect the steering angle and provide signal feedback.

[0049] The steering control valve 2 comprises a reversing valve 2.1, a flow amplification valve 2.2, and a hydraulic control bypass valve 2.3, the output end of the motor pump 3 is connected to the input end of the flow amplification valve 2.2, the output end of the flow amplification valve 2.2 is connected to the input end of the reversing valve 2.1, and the output L end and the output R end of the reversing valve 2.1 are respectively connected to the input end of the left turning oil cylinder 1.2 and the right turning oil cylinder 1.3; the hydraulic control bypass valve 2.3 is connected to the control end of the flow amplification valve 2.2 for damping control. Further, the steering control valve 2 further comprises a priority valve 2.4, the input end of the priority valve 2.4 is connected to the output end of the motor pump 3, the output CF end of the priority valve 2.4 is connected to the input end of the flow amplification valve 2.2 and the hydraulic steering gear 6.1, and the output EF end of the priority valve 2.4 is connected to the hydraulic working system. The high-pressure oil input by the motor pump 3 is preferentially distributed through the priority valve 2.4, one way through the output CF end into the flow amplification valve 2.2, and then into the left turning oil cylinder 1.2 or the right turning oil cylinder 1.3 through the reversing valve 2.1; the other way through the output EF end into other components of the hydraulic working system.

[0050] The steering gear comprises a steering wheel and a hydraulic steering gear 6.1, the steering wheel is connected to the control end of the hydraulic steering gear 6.1, the hydraulic steering gear 6.1 is connected to the control end of the steering control valve 2.1, and is used to drive the steering control valve 2.1 to act; the left turning control oil circuit and the right turning control oil circuit between the hydraulic steering gear 6.1 and the steering control valve 2.1 are further provided with a one-way valve and an electronic limit valve, which are respectively a left control one-way valve 8.1 and a left control electronic limit valve 7.1, a right control one-way valve 8.2 and a right control electronic limit valve 7.2, and the left control one-way valve 8.1 and the right control one-way valve 8.2 can reduce the influence on the reversing valve 2.1 when the steering is slightly operated or stopped, and if the one-way valve is not added, the reversing valve 2.1 will jump when the steering is stopped, causing the vehicle to turn a little after the steering is stopped, and the addition of the one-way valve can perfectly solve such problems.

[0051] When the left turning is at the limit position angle, the left control electronic limit valve 7.1 is powered on to cut off the left side flow of the hydraulic steering gear 6.1, so that the steering control oil circuit is cut off, and the displacement of the electric control plunger pump 3.1 in the motor pump 3 is first reduced to standby displacement, and the motor 3.2 is reduced in speed after the displacement is reduced to standby displacement; when the right turning is at the limit position angle, the right control electronic limit valve 7.2 is powered on to cut off the left side flow of the hydraulic steering gear 6.1, so that the steering control oil circuit is cut off, and the displacement of the electric control plunger pump 3.1 in the motor pump 3 is first reduced to standby displacement, and the motor 3.2 is reduced in speed after the displacement is reduced to standby displacement. The above control through the left control electronic limit valve 7.1 and the right control electronic limit valve 7.2 can reduce energy loss and ensure stable stopping of the whole vehicle when the left turning is at the limit position.

[0052] The steering gear 6 further comprises a rotation speed sensor 6.2 for detecting the rotation speed of the steering wheel. The corresponding steering flow is requested by detecting the rotation speed of the steering wheel, the greater the steering flow, the smaller the torque required for the steering wheel to rotate, and the better the driving experience.

[0053] The oil line connected by the motor pump 3 and the hydraulic steering gear 6.1 is further provided with an accumulator 4, the accumulator 4 comprises a one-way throttle valve 4.1 and an energy storage tank 4.2, the one-way throttle valve 4.1 is connected in series on the oil line connected by the motor pump 3 and the hydraulic steering gear 6.1, and the opening of the energy storage tank 4.2 is connected to the oil line connected by the one-way throttle valve pump 4.1 and the hydraulic steering gear 6.1, when the oil pressure is too low / insufficient flow, the energy storage tank 4.2 releases energy, increases the flow in the hydraulic steering gear 6.1 oil supply P loop, and ensures smooth rapid steering.

[0054] The motor pump 3 comprises a coaxially connected electric control plunger pump 3.1 and a motor 3.2, the electric control plunger pump 3.1 is used to provide oil supply power, and the motor 3.2 is used to drive the electric control plunger pump 3.1 to act. The input end of the electric control plunger pump 3.1 is connected with the hydraulic oil tank, and the output end is connected with the steering control valve 2 and the hydraulic steering gear 6.1, which is used to supply oil to the steering control valve 2 and the hydraulic steering gear 6.1.

[0055] Further, the electro-hydraulic steering start-stop smooth control system can also be provided with a controller 5, which is connected with the angle sensor 1.1, the rotation speed sensor 6.2, the motor 3.2, the left control electronic limit valve 7.1 and the right control electronic limit valve 7.2 through the controller, and the rotation speed of the motor 3.2 and the displacement of the electric control plunger pump 3.1, and the opening and closing of the left control electronic limit valve 7.1 and the right control electronic limit valve 7.2 are controlled by logic.

[0056] Embodiment two:

[0057] Based on the electro-hydraulic steering start-stop smooth control system of the engineering machinery provided in embodiment one, the embodiment of the present application provides a buffer control method of the electro-hydraulic steering start-stop smooth control system, as shown in Figure 2 The method comprises the following steps:

[0058] Step S1, obtaining the real-time steering angle of the steering actuator. The steering angle is obtained from the angle sensor 1.1.

[0059] Step S2, when the steering angle enters the steering angle buffer range of the limit position, the left turn control oil line or the right turn control oil line between the steering gear and the steering control valve is cut off through the corresponding electronic limit valve.

[0060] The steering angle buffer range is , The limit position of the steering angle is the calibration value, and the preset deviation value.

[0061] If the steering angle of the left turn enters the limit position of the steering angle buffer range, the left electronic limit valve 7.1 is opened to cut off the left turn control oil path between the steering gear and the steering control valve 2.

[0062] If the steering angle of the right turn enters the limit position of the steering angle buffer range, the right electronic limit valve 7.2 is opened to cut off the right turn control oil path between the steering gear and the steering control valve 2.

[0063] Step S3, the steering control valve stops working, the construction machinery is turned to the limit position under the action of inertia, the electric control plunger pump is quickly discharged, the motor speed is slowly reduced to the standby speed, and the construction machinery is stopped smoothly.

[0064] Example Three

[0065] Based on the electro-hydraulic steering start-stop smooth control system of the construction machinery provided in the example one, the example of the present application provides a smooth control method of the electro-hydraulic steering start-stop smooth control system, as shown in the figure, including the following steps: Figure 3

[0066] When the steering speed of the steering wheel is , the steering flow is not requested, the electric control plunger pump is in standby displacement, and the motor is in standby speed;

[0067] When the steering speed of the steering wheel is , it is judged as a misoperation, the steering flow is not requested, the electric control plunger pump is in standby displacement, and the motor is in standby speed;

[0068] When the steering speed of the steering wheel is , it is judged as normal steering operation, the requested steering flow is set to the calibrated flow, the target displacement of the electric control plunger pump is calculated through the flow-displacement interpolation table, the electric control plunger pump is raised from the standby displacement to the target displacement, and the motor is in standby speed;

[0069] When the steering speed of the steering wheel is , it is judged as normal steering operation, the requested steering flow is calculated through the steering wheel steering speed-flow interpolation table, the target displacement of the electric control plunger pump is calculated through the flow-displacement interpolation table, the electric control plunger pump is raised from the standby displacement to the target displacement, and the motor is in standby speed;

[0070] When the steering speed of the steering wheel is , it is judged as normal steering operation, the electric control plunger pump is raised from the standby displacement to the maximum displacement, the target speed of the motor is calculated through the steering wheel steering speed-motor speed interpolation table, and the motor is raised from the standby speed to the target speed.

[0071] ​Further, if it is detected that the steering is turned to the limit position or the electric control plunger pump is over-pressured and the motor is over the rated torque, the electric control plunger pump displacement is first reduced to the minimum standby displacement, and then the motor speed is reduced to the minimum standby speed, to ensure the stability of the system.

[0072] If it is detected that the steering wheel speed is 0 and this state is maintained for m seconds, and the work device handle signal is maintained as 0 within m seconds, the motor zero rotation is requested to achieve the purpose of green energy saving.

[0073] Embodiment Four

[0074] Based on the electro-hydraulic steering start-stop smooth control system of the engineering machinery provided in Embodiment One, an extreme angle calibration method of the electro-hydraulic steering start-stop smooth control system is provided, as shown in Figure 4 , comprising the following steps:

[0075] (1) Turn the engineering machinery to the limit position; specifically including the left limit position and the right limit position.

[0076] (2) Calibrate the steering angle corresponding to the limit position by pressing the calibration button on the controller, and record it as the calibration value ; the calibration value can be used for the buffer control in Embodiment Two.

[0077] (3) If re-calibration is needed, press the re-calibration button on the controller to clear the historical calibration data, and repeat the above two calibration steps to complete the re-calibration.

[0078] In summary, the flow amplification valve to the hydraulic steering gear is provided with a check valve and an accumulator, to prevent the on-off valve core in the flow amplification valve from moving back and forth, and the electric control plunger pump and the motor control are combined to eliminate the phenomenon of excessive starting torque during fast operation when starting steering, and the angle sensor at the hinge and the steering wheel speed sensor signal are combined to control the speed of the motor and the displacement of the electric control pump, to eliminate the whole machine shaking when stopping steering, and the mechanical limit valve is replaced by an electronic limit valve to solve the problem that the mechanical limit valve needs to be manually adjusted by the mechanical limit valve when the hydraulic control steering valve is at the limit position, the limit position calibration is performed by the angle sensor at the hinge, the whole machine offline calibration process is simplified, and the production efficiency is improved. The present application can significantly improve the steering driving experience of the engineering machinery, and simplify the whole machine steering calibration process.

[0079] Those skilled in the art will appreciate that embodiments of the present application can be readily used as software, hardware, or a combination of software and hardware. In a software embodiment, the methods can be tangibly embodied in a machine-readable storage medium having stored thereon instructions that can be used to program a computer to perform any of the methods. The software implementation can be initialized by loading and executing a set of instructions arranged to perform one of the methods into the computer's memory. Alternatively, hard-wired circuitry can be used in place of, or in combination with, software instructions. Thus, the

[0080] The present application is described in reference to the flowchart and / or block diagrams of the methods, apparatus (systems) and computer program products according to embodiments of the application. It will be understood that each block of the flowchart and / or block diagrams, and combinations of blocks in the flowchart and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart and / or block diagram block or blocks. Figure 1 one or more functions specified in one or more of the flowchart or block diagram block or blocks. Figure 1 means for performing the function specified by the flowchart or block diagram block or blocks.

[0081] These computer program instructions can also be stored in a computer- readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instructions which implement the flowchart or block diagram block or blocks. Figure 1 one or more functions specified in one or more of the flowchart or block diagram block or blocks. Figure 1 means for performing the function specified by the flowchart or block diagram block or blocks.

[0082] The computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the flowchart or block diagram block or blocks. Figure 1 one or more functions specified in one or more of the flowchart or block diagram block or blocks. Figure 1 means for performing the function specified by the flowchart or block diagram block or blocks.

[0083] The above description is only preferred embodiments of the present application. It is obvious that those skilled in the art can make some improvements and modifications without departing from the technical principles of the present application. These improvements and modifications should also be considered as falling within the protection scope of the present application.

Claims

1. A control method of an electro-hydraulic steering start-stop smooth control system, characterized by, The electro-hydraulic steering start-stop smooth control system comprises a steering actuator, a steering control valve, a steering gear and a motor pump; the steering gear comprises a steering wheel and a hydraulic steering gear, the steering wheel is connected with a control end of the hydraulic steering gear, the hydraulic steering gear is connected with a control end of the steering control valve, and is used for driving the steering control valve to act; a left turning control oil path and a right turning control oil path between the hydraulic steering gear and the steering control valve are further provided with a check valve and an electronic limit valve, which are used for ensuring the steering start-stop smoothness; the motor pump is connected with a hydraulic oil tank at an input end and connected with the steering control valve and the hydraulic steering gear at an output end, and is used for supplying oil to the steering control valve and the hydraulic steering gear; the motor pump comprises an electric control plunger pump and a motor which are coaxially connected, the electric control plunger pump is used for providing oil supply power, and the motor is used for driving the electric control plunger pump to act; The control method comprises a buffering control method and / or a smooth control method; The buffering control method comprises: acquiring a real-time steering angle of the steering actuator; when the steering angle enters a steering angle buffering range of a limit position, the left turning control oil path or the right turning control oil path between the hydraulic steering gear and the steering control valve is cut off through the corresponding electronic limit valve; the steering control valve stops working, the engineering machinery is turned to the limit position under the action of inertia, the electric control plunger pump is rapidly drained, the motor speed is slowly reduced to standby speed, and the engineering machinery is stopped smoothly; The turning angle buffer range is , The turning angle calibration value of the limit position is The preset deviation value is The smooth control method comprises: When the steering speed of the steering wheel is If the steering speed is less than the first threshold value, the steering flow is not requested, the electric control plunger pump is set to standby displacement, and the motor is set to standby speed. When the steering speed of the steering wheel If so, it is determined as a misoperation, and the steering flow is not requested, the electric control plunger pump is set to standby displacement, and the motor is set to standby speed. When the steering speed of the steering wheel If the steering speed is less than the threshold value, it is determined that the steering operation is normal, the request steering flow is set to the calibration flow, the target displacement of the electric control piston pump is calculated through the flow-displacement interpolation table, the electric control piston pump is raised from the standby displacement to the target displacement, and the motor is at the standby speed. When the steering speed of the steering wheel If yes, it is judged as normal steering operation, the requested steering flow is calculated through the steering speed-flow interpolation table of the steering wheel, the target displacement of the electric control piston pump is calculated through the flow-displacement interpolation table, the electric control piston pump is raised from the standby displacement to the target displacement, and the motor is at standby speed. When the steering speed of the steering wheel If the steering speed of the steering wheel is less than the threshold value, it is determined that the steering operation is normal, the electric control plunger pump is raised from standby displacement to maximum displacement, the target speed of the motor is calculated through the steering speed-motor speed interpolation table, and the motor is raised from standby speed to the target speed.

2. The control method of the electro-hydraulic steer-by-wire smooth control system according to claim 1, wherein the steering actuator comprises a left turning oil cylinder and a right turning oil cylinder; the steering control valve is connected with input ends of the left turning oil cylinder and the right turning oil cylinder, and is used for supplying oil to the left turning oil cylinder or the right turning oil cylinder.

3. The control method of the electro-hydraulic steer-by-wire smooth control system according to claim 2, wherein The steering actuator further comprises a left turning explosion-proof valve, a left turning check valve, a right turning explosion-proof valve and a right turning check valve which are used for pressure reduction and oil supplement, one end of the left turning explosion-proof valve and the left turning check valve is connected with the input end of the left turning oil cylinder, and the other end is connected with the hydraulic oil tank; one end of the right turning explosion-proof valve and the right turning check valve is connected with the input end of the right turning oil cylinder, and the other end is connected with the hydraulic oil tank.

4. The control method of the electro-hydraulic steer-by-wire smooth control system according to claim 2, wherein The steering actuator further comprises an angle sensor which is used for detecting a steering angle, and the angle sensor is arranged at a hinged position of the left turning oil cylinder or the right turning oil cylinder and a steering wheel.

5. The control method of the electro-hydraulic steer-by-wire smooth control system according to claim 2, wherein The steering control valve comprises a reversing valve, a flow amplification valve and a hydraulic control bypass valve, the output end of the motor pump is connected to the input end of the flow amplification valve, the output end of the flow amplification valve is connected to the input end of the reversing valve, the output L end and the output R end of the reversing valve are respectively connected to the input ends of the left turning oil cylinder and the right turning oil cylinder; the hydraulic control bypass valve is connected to the control end of the flow amplification valve for damping control.

6. The control method of the electro-hydraulic steer-by-wire smooth control system according to claim 5, wherein The steering control valve further comprises a priority valve, the input end of the priority valve is connected with the output end of the motor pump, the output CF end of the priority valve is connected with the input ends of the flow amplification valve and the hydraulic steering gear, and the output EF end of the priority valve is connected to a hydraulic working system.

7. The control method of the electro-hydraulic steer-by-wire smooth control system according to claim 1, wherein The oil circuit connected with the motor pump and the hydraulic steering gear further comprises an accumulator, the accumulator comprising a one-way throttle valve and an accumulator tank, the one-way throttle valve being connected in series with the oil circuit connected with the motor pump and the hydraulic steering gear, and the opening of the accumulator tank being connected to the oil circuit connected with the one-way throttle valve and the hydraulic steering gear, the accumulator being used for assisting steering smoothness of the hydraulic steering gear.

8. The control method of the electro-hydraulic steer-by-wire smooth control system according to claim 1, wherein The steering gear further comprises a rotating speed sensor, the rotating speed sensor being used for detecting a steering rotating speed of the steering wheel.

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