Electro-hydraulic steering start-stop stability control system of engineering machinery and control method of electro-hydraulic steering start-stop stability control system

Abstract

The invention discloses an electro-hydraulic steering start-stop stability control system of engineering machinery and a control method of the electro-hydraulic steering start-stop stability control system in the technical field of engineering machinery, and the system comprises a steering execution mechanism which comprises a left-turning oil cylinder and a right-turning oil cylinder; the steering control valve is 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; the steering gear comprises a steering wheel and a hydraulic steering gear, the steering wheel is connected with the control end of the hydraulic steering gear, and the hydraulic steering gear is connected with the control end of the steering control valve and used for driving the steering control valve to act; a one-way valve and an electronic limiting valve are further arranged on a control oil way between the hydraulic steering gear and the steering control valve and used for ensuring stable steering start and stop; the input end of the motor pump is connected with the hydraulic oil tank, and the output end of the motor pump is connected with the steering control valve and the hydraulic steering gear and used for supplying oil to the steering control valve and the hydraulic steering gear. Based on the system and the corresponding control method, the steering operation experience of the engineering machinery can be remarkably improved.

Description

Technical Field

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

[0002] As construction machinery is transforming towards electric control, intelligence and greenness, higher requirements are placed on the wire control steering system. There are generally three types of steering systems for construction machinery: deflection type, articulated type and sliding type. Among them, articulated steering vehicles refer to vehicles whose bodies are composed of two or more separate front and rear frames, and whose steering purpose is achieved by relative deflection of the front and rear frames through hydraulic or other forms of action, such as loaders, rollers, graders and mining trucks. Compared with other steering methods, articulated steering has many advantages, such as small turning radius. Under the same wheelbase and track, the turning radius of articulated steering is about 80% of the turning radius of front wheel steering. If the braking torque can be used reasonably, the turning radius can be further reduced; since there is no need to overcome the sliding resistance, the energy consumed in the steering process is low; there is no relative deflection between the wheel and the frame, and no steering drive axle is required. These advantages have prompted more and more manufacturers to choose this simple and efficient steering method for construction vehicles. The widespread use of articulated steering engineering vehicles in construction has exposed some shortcomings. Among them, the shortcoming that has the greatest impact on safety is its poor lateral stability. Articulated steering engineering vehicles are required to travel on roads in some countries and regions, with relatively high speeds, and have high requirements for steering stability. Conventional flow amplification steering systems are prone to large steering shocks and unstable steering when turning at high speeds. As a result, the stability and safety of articulated wire-controlled steering engineering vehicles have gradually been valued by people. Summary of the invention

[0003] The purpose of the present invention is to overcome the deficiencies in the prior art, to provide an electro-hydraulic steering start-stop smooth control system for engineering machinery and a control method thereof, and to solve the technical problem of how to improve the stability and safety of articulated wire-controlled steering engineering vehicles.

[0004] To achieve the above object, the present invention is implemented by adopting the following technical solutions: In a first aspect, the present invention provides an electro-hydraulic steering start-stop smooth control system for engineering machinery, comprising: Steering actuator, including left-turn cylinder and right-turn cylinder; A steering control valve connected to the input ends of the left-turn oil cylinder and the right-turn oil cylinder, and used for supplying oil to the left-turn oil cylinder or the right-turn oil cylinder; The steering gear comprises a steering wheel and a hydraulic steering gear, wherein the steering wheel is connected to a control end of the hydraulic steering gear, and the hydraulic steering gear is connected to a control end of the steering control valve, and is used to drive the steering control valve to operate; 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, and are used to ensure smooth start and stop of the steering; The motor pump has an input end connected to the hydraulic oil tank and an output end connected to the steering control valve and the hydraulic steering gear, and is used for supplying oil to the steering control valve and the hydraulic steering gear.

[0005] Optionally, the steering actuator also 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 reducing pressure and replenishing oil. One end of the left-turn explosion-proof valve and the left-turn check valve is 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 is connected to the input end of the right-turn cylinder, and the other end is connected to the hydraulic oil tank.

[0006] Optionally, the steering actuator further includes an angle sensor for detecting a steering angle, and the angle sensor is disposed at a hinge between the left-turn cylinder or the right-turn cylinder and the turntable.

[0007] Optionally, the steering control valve includes a reversing valve, a flow amplifying valve and a hydraulically controlled bypass valve, the output end of the motor pump is connected to the input end of the flow amplifying valve, the output end of the flow amplifying 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-turn cylinder and the right-turn cylinder; the hydraulically controlled bypass valve is connected to the control end of the flow amplifying valve for damping control.

[0008] Optionally, the steering control valve also includes a priority valve, the input end of the priority valve is connected to the output end of the motor pump, the output CF end of the priority valve is connected to the input end of the flow amplification valve and the hydraulic steering gear, and the output EF end of the priority valve is connected to the hydraulic working system.

[0009] Optionally, an accumulator is also provided on the oil circuit connecting the motor pump and the hydraulic steering gear, and the accumulator includes a one-way throttle valve and an energy storage tank. The one-way throttle valve is connected in series to the oil circuit connecting the motor pump and the hydraulic steering gear, and the opening of the energy storage tank is connected to the oil circuit connecting the one-way throttle valve pump and the hydraulic steering gear. The accumulator is used to assist the hydraulic steering gear in steering smoothly.

[0010] Optionally, the steering gear also includes a rotation speed sensor, and the rotation speed sensor is used to detect the steering speed of the steering wheel.

[0011] Optionally, the motor pump includes an electrically controlled plunger pump and a motor that are coaxially connected, the electrically controlled plunger pump is used to provide oil supply power, and the motor is used to drive the electrically controlled plunger pump to operate.

[0012] In a second aspect, the present invention provides a buffer control method for an electro-hydraulic steering start-stop smooth control system, using the electro-hydraulic steering start-stop smooth control system, the buffer control method comprising: Obtaining the real-time steering angle of the steering actuator; When the steering angle enters the steering angle buffer range of the extreme position, the left turn control oil circuit or the right turn control oil circuit between the hydraulic steering gear and the steering control valve is cut off by the corresponding electronic limit valve; The steering control valve stops working, and the construction machinery turns to the limit position under the action of inertia. The electric-controlled plunger pump quickly returns the pump, and the motor speed slowly drops to the standby speed, so that the construction machinery stops smoothly. Wherein, the steering angle buffer range is , is the steering angle calibration value of the extreme position, is the preset deviation value.

[0013] In a third aspect, the present invention provides a smooth control method of an electro-hydraulic steering start-stop smooth control system, using the above-mentioned electro-hydraulic steering start-stop smooth control system, the smooth control method comprising: When the steering wheel speed , then no steering flow is requested, the electronically controlled piston pump is set to standby displacement, and the motor is set to standby speed; When the steering wheel speed , it is judged as a wrong operation, and the steering flow is not requested. The electronically controlled plunger pump is set to standby displacement and the motor is set to standby speed; When the steering wheel speed , it is judged as a normal steering operation, the steering flow is requested to be set to the calibrated flow, the target displacement of the electronically controlled piston pump is calculated by the flow-displacement interpolation table, the electronically controlled piston pump is increased from the standby displacement to the target displacement, and the motor is at the standby speed; When the steering wheel speed , it is judged as a normal steering operation, the requested steering flow is calculated through the steering wheel steering speed-flow interpolation table, the target displacement of the electronically controlled plunger pump is calculated through the flow-displacement interpolation table, the electronically controlled plunger pump is increased from the standby displacement to the target displacement, and the motor is at the standby speed; When the steering wheel speed , it is judged as a normal steering operation, the electronically controlled plunger pump is increased from the standby displacement to the maximum displacement, the target speed of the motor is calculated by the steering wheel steering speed-motor speed interpolation table, and the motor is increased from the standby speed to the target speed.

[0014] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides an electro-hydraulic steering start-stop smooth control system and control method for engineering machinery. The system ensures the smooth start-stop of the steering of the engineering machinery and has certain economy and universality. On the basis of the system, the buffer control method and the smooth control method respectively control the motor, the electric control plunger pump and the electronic limit valve L / R, eliminating the problems of large steering wheel starting torque, large shock and shaking when stopping the whole machine, non-energy-saving steering system, and cumbersome steering limit position calibration process and poor effect generated in the conventional system. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a structural schematic diagram of an electro-hydraulic steering start-stop smooth control system for engineering machinery provided by an embodiment of the present invention; Figure 2 It is a flow chart of a buffer control method of an electro-hydraulic steering start-stop smooth control system provided by an embodiment of the present invention; Figure 3 It is a flow chart of a stable control method of an electro-hydraulic steering start-stop stable control system provided by an embodiment of the present invention; Figure 4 It is a schematic diagram of a flow chart of a limit angle calibration of an electro-hydraulic steering start-stop stability control system provided by an embodiment of the present invention; The markings in the figure are: 1. Steering actuator; 1.1. Angle sensor; 1.2. Left-turn cylinder; 1.3. Right-turn cylinder; 1.4. Left-turn explosion-proof valve; 1.5. Left-turn check valve; 1.6. Right-turn explosion-proof valve; 1.7. Right-turn check valve; 2. Steering control valve; 2.1. Directional valve; 2.2. Flow amplification valve; 2.3. Hydraulic bypass valve; 2.4. Priority valve; 3. Motor pump; 3.1. Electric-controlled plunger pump; 3.2. Motor; 4. Accumulator; 4.1. One-way throttle valve; 4.2. Accumulator tank; 5. Controller; 6. Steering gear; 6.1. Hydraulic steering gear; 6.2. Speed ​​sensor; 7. Electronic limit valve; 7.1. Left control electronic limit valve; 7.2. Right control electronic limit valve; 8. Check valve; 8.1. Left control check valve; 8.2. Right control check valve. DETAILED DESCRIPTION

[0016] 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 solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0017] Embodiment 1:

[0018] like Figure 1 As shown, an embodiment of the present 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.

[0019] The steering actuator includes a left-turn oil cylinder 1.2 and a right-turn oil cylinder 1.3, which are used to drive the articulated wire-controlled steering mechanism to rotate. When the left-turn oil cylinder 1.2 is supplied with oil and works, a left turn is achieved, and when the right-turn oil cylinder 1.3 is supplied with oil and works, a right turn is achieved.

[0020] 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 oil 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 oil 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 to reduce pressure and replenish oil to ensure normal steering action.

[0021] The steering actuator also includes an angle sensor 1.1, which is arranged at the hinge between the left-turn oil cylinder 1.2 or the right-turn oil cylinder 1.3 and the turntable, and is used to detect the steering angle and provide signal feedback.

[0022] The steering control valve 2 includes a reversing valve 2.1, a flow amplifying valve 2.2 and a hydraulically controlled bypass valve 2.3. The output end of the motor pump 3 is connected to the input end of the flow amplifying valve 2.2, the output end of the flow amplifying valve 2.2 is connected to the input end of the reversing valve 2.1, the output L end and the output R end of the reversing valve 2.1 are respectively connected to the input ends of the left-turn oil cylinder 1.2 and the right-turn oil cylinder 1.3; the hydraulically controlled bypass valve 2.3 is connected to the control end of the flow amplifying valve 2.2 for damping control. Further, the steering control valve 2 also includes 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 amplifying 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 passes through the output CF end to enter the flow amplifier valve 2.2, and then passes through the reversing valve 2.1 to enter the left-turn cylinder 1.2 or the right-turn cylinder 1.3; the other way passes through the output EF end to enter other components of the hydraulic working system.

[0023] The steering gear includes 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 to drive the steering control valve 2.1 to operate. A check 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 6.1 and the steering control valve 2.1, which are respectively denoted as a left control check valve 8.1 and a left control electronic limit valve 7.1, and a right control check valve 8.2 and a right control electronic limit valve 7.2. The left control check valve 8.1 and the right control check valve 8.2 can reduce the influence of a small steering operation or a stop operation on the reversing valve 2.1. If no check valve is added, the reversing valve 2.1 will jump when the steering stops, causing it to rotate after the steering stops. Adding a check valve can perfectly solve this problem.

[0024] When the left turn is at the extreme position angle, the left control electronic limit valve 7.1 is energized, cutting off the left flow of the hydraulic steering gear 6.1, so that the steering control oil circuit is cut off, and at the same time, the displacement of the electronically controlled plunger pump 3.1 in the motor pump 3 is first reduced to the standby displacement, and the motor 3.2 reduces the speed after the displacement is reduced to the standby displacement; when the right turn is at the extreme position angle, the right control electronic limit valve 7.2 is energized, cutting off the left flow of the hydraulic steering gear 6.1, so that the steering control oil circuit is cut off, and the displacement of the electronically controlled plunger pump 3.1 in the motor pump 3 is first reduced to the standby displacement, and the motor 3.2 reduces the speed after the displacement is reduced to the standby displacement. The above control of the left control electronic limit valve 7.1 and the right control electronic limit valve 7.2 can reduce energy loss and ensure that the whole vehicle stops smoothly when stopping at the left steering extreme position.

[0025] The steering gear 6 also includes a speed sensor 6.2, which is used to detect the steering speed of the steering wheel. The corresponding steering flow is requested by detecting the steering wheel speed. The greater the steering flow, the smaller the torque required for steering wheel rotation, and the better the driving experience.

[0026] An accumulator 4 is also provided on the oil circuit connecting the motor pump 3 and the hydraulic steering gear 6.1. 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 to the oil circuit connecting the motor pump 3 and the hydraulic steering gear 6.1. The opening of the energy storage tank 4.2 is connected to the oil circuit connecting the one-way throttle valve pump 4.1 and the hydraulic steering gear 6.1. When the oil pressure is too low / the flow rate is insufficient, the energy storage tank 4.2 releases energy to increase the flow rate in the oil supply P circuit of the hydraulic steering gear 6.1, thereby ensuring fast and smooth steering.

[0027] The motor pump 3 includes 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 operate. The input end of the electric control plunger pump 3.1 is connected to the hydraulic oil tank, and the output end is connected to the steering control valve 2 and the hydraulic steering gear 6.1, and is used to supply oil to the steering control valve 2 and the hydraulic steering gear 6.1.

[0028] Furthermore, the electro-hydraulic steering start-stop smooth control system can also be provided with a controller 5, which is connected to the angle sensor 1.1, the 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 speed of the motor 3.2 and the displacement of the electric control plunger pump 3.1, as well as the switching of the left control electronic limit valve 7.1 and the right control electronic limit valve 7.2 are controlled through logic.

[0029] Embodiment 2:

[0030] Based on the electro-hydraulic steering start-stop smooth control system for engineering machinery provided in Example 1, the embodiment of the present invention provides a buffer control method for the electro-hydraulic steering start-stop smooth control system, such as Figure 2 As shown, the following steps are included: Step S1, obtaining the real-time steering angle of the steering actuator. The steering angle is obtained from the angle sensor 1.1.

[0031] Step S2: When the steering angle enters the steering angle buffer range of the extreme position, the left turn control oil circuit or the right turn control oil circuit between the steering gear and the steering control valve is cut off by the corresponding electronic limit valve.

[0032] Steering angle buffer range is , is the steering angle calibration value of the extreme position, is the preset deviation value.

[0033] If the left turn steering angle enters the steering angle buffer range of the extreme position, the left turn control oil circuit between the steering gear and the steering control valve 2 is cut off by the left electronic limit valve 7.1.

[0034] If the right turn steering angle enters the steering angle buffer range of the extreme position, the right turn control oil circuit between the steering gear and the steering control valve 2 is cut off by the right electronic limit valve 7.2.

[0035] Step S3, the steering control valve stops working, the engineering machinery turns to the extreme position under the action of inertia, the electric-controlled plunger pump quickly returns, and the motor speed slowly drops to the standby speed, so that the engineering machinery stops smoothly.

[0036] Embodiment three: Based on the electro-hydraulic steering start-stop smooth control system for engineering machinery provided in Example 1, the embodiment of the present invention provides a smooth control method of the electro-hydraulic steering start-stop smooth control system, such as Figure 3 As shown, the following steps are included: When the steering wheel speed , then no steering flow is requested, the electronically controlled piston pump is set to standby displacement, and the motor is set to standby speed; When the steering wheel speed , it is judged as a wrong operation, and the steering flow is not requested. The electronically controlled plunger pump is set to standby displacement and the motor is set to standby speed; When the steering wheel speed , it is judged as a normal steering operation, the steering flow is requested to be set to the calibrated flow, the target displacement of the electronically controlled piston pump is calculated through the flow-displacement interpolation table, the electronically controlled piston pump is increased from the standby displacement to the target displacement, and the motor is at the standby speed; When the steering wheel speed , it is judged as a normal steering operation, the requested steering flow is calculated through the steering wheel steering speed-flow interpolation table, the target displacement of the electronically controlled plunger pump is calculated through the flow-displacement interpolation table, the electronically controlled plunger pump is increased from the standby displacement to the target displacement, and the motor is at the standby speed; When the steering wheel speed , it is judged as a normal steering operation, and the electronically controlled plunger pump is increased 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 increased from the standby speed to the target speed.

[0037] Furthermore, if it is detected that the steering has reached the extreme position or the electric control plunger pump is over-pressured and the motor exceeds the rated torque, the displacement of the electric control plunger pump is first reduced to the minimum standby displacement, and then the motor speed is reduced to the minimum standby speed to ensure system stability.

[0038] If the steering wheel speed is detected to be 0 and this state is maintained for m seconds, and the working device handle signal remains 0 within m seconds, the motor is requested to rotate at zero to achieve the purpose of green energy saving.

[0039] Embodiment 4:

[0040] Based on the electro-hydraulic steering start-stop smooth control system for engineering machinery provided in Example 1, the embodiment of the present invention provides a limit angle calibration method for the electro-hydraulic steering start-stop smooth control system, such as Figure 4 As shown, the following steps are included: (1) Turn the construction machinery to the extreme position, including the left turn extreme position and the right turn extreme position.

[0041] (2) Press the calibration button on the controller to calibrate the steering angle corresponding to the extreme position and record it as the calibration value. ; Calibration value It can be used for the buffer control in the second embodiment.

[0042] (3) If recalibration is required, press the recalibration button on the controller to clear the historical calibration data, repeat the above two calibration steps to complete the recalibration.

[0043] In summary, the present invention adds a one-way valve and an accumulator from the flow amplification valve to the hydraulic steering gear to prevent the switch valve core in the flow amplification valve from moving back and forth, and combines the electronically controlled plunger pump and motor control to eliminate the phenomenon of excessive starting torque during quick operation when steering starts, and combines the angle sensor at the hinge and the steering wheel speed sensor signal to control the motor speed and the displacement of the electronically controlled pump to eliminate the shaking of the whole machine when the steering stops. In view of the problem that the hydraulic steering valve needs to manually adjust the mechanical limit valve when the steering limit position is reached, the mechanical limit valve is changed to an electronic limit valve, and the steering limit position is calibrated in combination with the angle sensor at the hinge, which simplifies the off-line calibration process of the whole machine and improves production efficiency. The present invention can significantly improve the steering driving experience of engineering machinery and simplify the steering calibration process of the whole machine.

[0044] It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0045] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0046] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0047] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0048] 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. An electro-hydraulic steering start-stop smooth control system for engineering machinery, characterized in that: include: Steering actuator, including left-turn cylinder and right-turn cylinder; A steering control valve connected to the input ends of the left-turn oil cylinder and the right-turn oil cylinder, and used for supplying oil to the left-turn oil cylinder or the right-turn oil cylinder; The steering gear comprises a steering wheel and a hydraulic steering gear, wherein the steering wheel is connected to a control end of the hydraulic steering gear, and the hydraulic steering gear is connected to a control end of the steering control valve, and is used to drive the steering control valve to operate; 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, and are used to ensure smooth start and stop of the steering; The motor pump has an input end connected to the hydraulic oil tank and an output end connected to the steering control valve and the hydraulic steering gear, and is used for supplying oil to the steering control valve and the hydraulic steering gear.

2. The electro-hydraulic steering start-stop smooth control system for engineering machinery according to claim 1, characterized in that: The steering actuator also 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 reducing pressure and replenishing oil. One end of the left-turn explosion-proof valve and the left-turn check valve is 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 is connected to the input end of the right-turn cylinder, and the other end is connected to the hydraulic oil tank.

3. The electro-hydraulic steering start-stop smooth control system for engineering machinery according to claim 1, characterized in that: The steering actuator also includes an angle sensor for detecting a steering angle, and the angle sensor is arranged at a hinge between the left-turn oil cylinder or the right-turn oil cylinder and the turntable.

4. The electro-hydraulic steering start-stop smooth control system for engineering machinery according to claim 1, characterized in that: The steering control valve includes a reversing valve, a flow amplifying valve and a hydraulically controlled bypass valve. The output end of the motor pump is connected to the input end of the flow amplifying valve, the output end of the flow amplifying 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-turn cylinder and the right-turn cylinder; the hydraulically controlled bypass valve is connected to the control end of the flow amplifying valve for damping control.

5. The electro-hydraulic steering start-stop smooth control system for engineering machinery according to claim 4, characterized in that: The steering control valve also includes a priority valve, the input end of the priority valve is connected to the output end of the motor pump, the output CF end of the priority valve is connected to the input end of the flow amplification valve and the hydraulic steering gear, and the output EF end of the priority valve is connected to the hydraulic working system.

6. The electro-hydraulic steering start-stop smooth control system for engineering machinery according to claim 1, characterized in that: An accumulator is also provided on the oil circuit 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 to the oil circuit connecting the motor pump and the hydraulic steering gear. The opening of the accumulator tank is connected to the oil circuit connecting the one-way throttle valve pump and the hydraulic steering gear. The accumulator is used to assist the hydraulic steering gear in steering smoothly.

7. The electro-hydraulic steering start-stop smooth control system for engineering machinery according to claim 1, characterized in that: The steering gear further comprises a rotation speed sensor, and the rotation speed sensor is used for detecting the steering rotation speed of the steering wheel.

8. The electro-hydraulic steering start-stop smooth control system for engineering machinery according to any one of claims 1 to 7, characterized in that: The motor pump comprises an electrically controlled plunger pump and a motor which are coaxially connected. The electrically controlled plunger pump is used to provide oil supply power, and the motor is used to drive the electrically controlled plunger pump to operate.

9. A buffer control method for an electro-hydraulic steering start-stop smooth control system, characterized in that: Using the electro-hydraulic steering start-stop smooth control system as claimed in claim 8, the buffer control method includes: Obtaining the real-time steering angle of the steering actuator; When the steering angle enters the steering angle buffer range of the extreme position, the left turn control oil circuit or the right turn control oil circuit between the hydraulic steering gear and the steering control valve is cut off by the corresponding electronic limit valve; The steering control valve stops working, and the construction machinery turns to the limit position under the action of inertia. The electric-controlled plunger pump quickly returns the pump, and the motor speed slowly drops to the standby speed, so that the construction machinery stops smoothly. Wherein, the steering angle buffer range is , is the steering angle calibration value of the extreme position, is the preset deviation value.

10. A stable control method for an electro-hydraulic steering start-stop stable control system, characterized in that: The electro-hydraulic steering start-stop smooth control system according to claim 8 is adopted, and the smooth control method comprises: When the steering wheel speed , then no steering flow is requested, the electronically controlled piston pump is set to standby displacement, and the motor is set to standby speed; When the steering wheel speed , it is judged as a wrong operation, and the steering flow is not requested. The electronically controlled plunger pump is set to standby displacement and the motor is set to standby speed; When the steering wheel speed , it is judged as a normal steering operation, the steering flow is requested to be set to the calibrated flow, the target displacement of the electronically controlled piston pump is calculated by the flow-displacement interpolation table, the electronically controlled piston pump is increased from the standby displacement to the target displacement, and the motor is at the standby speed; When the steering wheel speed , it is judged as a normal steering operation, the requested steering flow is calculated through the steering wheel steering speed-flow interpolation table, the target displacement of the electronically controlled plunger pump is calculated through the flow-displacement interpolation table, the electronically controlled plunger pump is increased from the standby displacement to the target displacement, and the motor is at the standby speed; When the steering wheel speed , it is judged as a normal steering operation, the electronically controlled plunger pump is increased from the standby displacement to the maximum displacement, the target speed of the motor is calculated by the steering wheel steering speed-motor speed interpolation table, and the motor is increased from the standby speed to the target speed.

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