An electrically controlled grading valve group for a motor grader and a hydraulic system of a full drive motor grader

Abstract

The utility model provides a kind of for motor grader's electric control leveling valve group and the hydraulic system of full drive motor grader, it is related to motor grader field, the scheme used is: including proportional reversing valve one and proportional reversing valve two, the oil inlet of proportional reversing valve one and proportional reversing valve two can be communicated with oil supply pump, the oil outlet of proportional reversing valve one and proportional reversing valve two can be communicated with left lifting oil cylinder and right lifting oil cylinder respectively, further include pilot valve one and pilot valve two, the electrical signal interface of pilot valve one and pilot valve two can be electrically connected with motor grader controller, the oil inlet of pilot valve one and pilot valve two can be communicated with oil supply pump, the oil outlet of pilot valve one is communicated with the control oil port of proportional reversing valve one, the oil outlet of pilot valve two is communicated with the control oil port of proportional reversing valve two.The utility model can automatically adjust spade position, improve the automation level and accuracy of adjustment.

Description

Technical Field

[0001] This utility model relates to the field of motor graders, and in particular to an electrically controlled leveling valve assembly for motor graders and a hydraulic system for all-drive motor graders. Background Technology

[0002] The leveling hydraulic system of a grader is the core module for achieving its high-precision leveling operation. It is mainly used to control the lifting, tilting, and lateral movement of the scraper (shovel) to ensure the ground is flat. This system uses hydraulic power to drive the actuators, combined with sensors and a control system to achieve automated leveling, and is widely used in road construction, mining, farmland reclamation, and other scenarios.

[0003] In the prior art, Chinese invention patent CN 106836337 B discloses a variable displacement hydraulic system for a grader, including shuttle valve I, shuttle valve II, load-sensitive multi-way valve I, and load-sensitive multi-way valve II. Load-sensitive multi-way valves I and II are connected to an oil tank via a priority valve and a load-sensitive piston pump. The other five valves in load-sensitive multi-way valve I are connected to corresponding actuators, and the other five valves in load-sensitive multi-way valve II are connected to other corresponding actuators. Load-sensitive multi-way valve I is connected to the right lifting cylinder of the blade. Valve II is connected to the left lifting cylinder of the shovel blade. The two inlets of shuttle valve I are connected to the load-sensitive port of the priority valve and the load-sensitive multi-way valve I, respectively. The outlet of shuttle valve I is connected to the control port of the load-sensitive plunger pump. The two inlets of shuttle valve II are connected to the load-sensitive port of the filling valve and the load-sensitive port of the steering gear, respectively. The outlet of shuttle valve II is connected to the load-sensitive port of the priority valve. In this technical solution, the load-sensitive variable pump has the function of sensing the load, which can ensure that the flow rate and pressure are continuously matched with the power demand, and the power consumption is low.

[0004] In the above technical solution, load-sensitive multi-way valve I is connected to the right lifting cylinder of the blade, and load-sensitive multi-way valve II is connected to the left lifting cylinder of the blade. During adjustment, the load-sensitive multi-way valve first requires the operator to apply force to the pilot handle, and then responds to drive the right and left lifting cylinders of the blade to adjust the blade angle. This adjustment method has a low level of automation and relies entirely on the operator's experience to convert the blade position information into the flow information of the load-sensitive multi-way valve, resulting in low adjustment accuracy. Utility Model Content

[0005] To address the technical problems of low automation and insufficient precision in adjusting the two blade lifting cylinders of graders in the prior art, this utility model provides an electronically controlled leveling valve assembly for graders and a hydraulic system for all-drive graders, which can automatically adjust the blade position, improving the automation level and accuracy of the adjustment.

[0006] In a first aspect, this utility model provides an electrically controlled leveling valve assembly for a grader to solve the above-mentioned technical problems. The assembly includes a proportional directional valve one and a proportional directional valve two. The oil inlets of both the proportional directional valve one and the proportional directional valve two are connected to an oil supply pump. The oil outlet of the proportional directional valve one is connected to a left lifting cylinder, and the oil outlet of the proportional directional valve two is connected to a right lifting cylinder. The assembly also includes a pilot valve one and a pilot valve two. The electrical signal interfaces of both the pilot valve one and the pilot valve two are electrically connected to a grader controller. The oil inlets of both the pilot valve one and the pilot valve two are connected to an oil supply pump. The oil outlet of the pilot valve one is connected to the control port of the proportional directional valve one, and the oil outlet of the pilot valve two is connected to the control port of the proportional directional valve two.

[0007] This invention converts the adjustment electrical signal of the blade into a pressure signal of the pilot valve by setting pilot valve one and pilot valve two, and then into a flow signal of the proportional directional valve, so as to realize the electronic leveling of the whole vehicle controller, eliminating manual operation and control, and achieving a high level of automation and high accuracy in leveling.

[0008] Furthermore, the oil inlets of the first pilot valve and the second pilot valve are respectively connected to the oil outlet of the pilot pressure reducing valve, and the oil inlet of the pilot pressure reducing valve can be connected to the oil supply pump.

[0009] This invention reduces pilot oil pressure by setting a pilot pressure reducing valve, thus preventing damage to pilot valve one and pilot valve two due to excessive pressure.

[0010] Furthermore, the oil outlet of the pilot pressure reducing valve is also connected to the oil inlet of the pilot relief valve, and the oil outlet of the pilot relief valve can be connected to the oil tank.

[0011] This invention prevents excessive pressure in the pilot oil circuit from damaging pilot valve 1, pilot valve 2, proportional directional valve 1, and proportional directional valve 2 by setting a pilot relief valve.

[0012] Furthermore, it also includes shuttle valve one and shuttle valve two. The two oil inlets of shuttle valve two are respectively connected to the oil tank and the load sensitive port of the proportional directional valve two. The oil outlet of shuttle valve two is connected to one oil inlet of shuttle valve one, and the other oil inlet of shuttle valve one is connected to the load sensitive port of the proportional directional valve one. The oil inlet of the proportional directional valve one can be connected to the oil supply pump through compensation valve one, and the oil inlet of the proportional directional valve two can be connected to the oil supply pump through compensation valve two.

[0013] This invention enables the output of the larger load signal from two proportional directional valves by setting shuttle valve one and shuttle valve two, thereby meeting the working requirements of lifting cylinders with larger loads.

[0014] Secondly, this utility model also provides a hydraulic system for an all-wheel drive grader, including an oil tank, an oil supply pump, a left lifting cylinder, a right lifting cylinder, a left front wheel travel motor, and a right front wheel travel motor. It also includes the aforementioned electrically controlled leveling valve assembly for the grader. The left front wheel travel motor is connected to the oil supply pump and the oil tank via a first directional control valve. The inlet of the first directional control valve is connected to the oil supply pump via a third compensation valve. The right front wheel travel motor is connected to the oil supply pump and the oil tank via a second directional control valve. The oil inlet of the second directional switch valve is connected to the oil supply pump through the fourth compensation valve. The oil supply pump is a load-sensitive variable pump. The oil outlet of the first shuttle valve is connected to one oil inlet of the fourth shuttle valve. The other oil inlet of the fourth shuttle valve is connected to the load-sensitive port of the second directional switch valve. The oil outlet of the fourth shuttle valve is connected to one oil inlet of the third shuttle valve. The other oil inlet of the third shuttle valve is connected to the load-sensitive port of the first directional switch valve. The oil outlet of the third shuttle valve is connected to the control port of the oil supply pump.

[0015] This invention employs a load-sensitive variable pump as the oil supply pump and incorporates shuttle valves three and four, as well as an electrically controlled leveling valve assembly for graders with shuttle valves one and two. This allows for accurate and timely adjustment of the oil supply pump's flow rate, ensuring that the maximum load requirements of the left front wheel travel motor, right front wheel travel motor, left lifting cylinder, and right lifting cylinder are met. Simultaneously, through the actions of compensation valves one, two, three, and four, the pressure difference between the inlet and outlet of the corresponding directional valves is maintained constant, ensuring that the flow rate through the valves does not fluctuate with changes in the adjusted load pressure.

[0016] Furthermore, it also includes an overflow valve, the oil inlet of which can be connected to the oil supply pump, and the oil outlet of which can be connected to the oil tank.

[0017] This invention, by setting an overflow valve, can ensure that the oil supply pressure of the main oil circuit is within a safe range, and avoid damage to working components such as the travel motor on the main oil circuit due to excessive pressure.

[0018] Furthermore, it also includes pilot valve three and pilot valve four, which are electrically connected to the controller. The oil inlet of pilot valve three and pilot valve four is connected to the oil outlet of the pilot pressure reducing valve. The oil outlet of pilot valve three is connected to the control oil port of the switching directional valve one, and the oil outlet of pilot valve four is connected to the control oil port of the switching directional valve two.

[0019] Furthermore, it also includes a two-position three-way solenoid valve one and a two-position three-way solenoid valve two. Both the two-position three-way solenoid valve one and the two-position three-way solenoid valve two are electrically connected to the controller. The oil inlet of both the two-position three-way solenoid valve one and the two-position three-way solenoid valve two is connected to the oil supply pump. The oil return port of both the two-position three-way solenoid valve one and the two-position three-way solenoid valve two is connected to the oil tank. The oil outlet of the two-position three-way solenoid valve one is connected to the displacement control port of the left front wheel travel motor and the right front wheel travel motor, respectively. The oil outlet of the two-position three-way solenoid valve two is connected to the free wheel oil supply port of the left front wheel travel motor and the right front wheel travel motor, respectively.

[0020] This invention uses a two-position three-way solenoid valve to adjust the displacement of the left and right front wheel travel motors, enabling precise control of the motors' mechanical motion states (such as speed, torque, and power). The two-position three-way solenoid valve allows the travel motors to rotate freely without the application of hydraulic driving force, meeting the actual needs of the equipment in scenarios such as transportation, maintenance, and emergency handling, and avoiding mechanical failures or operational risks caused by motor lock-up.

[0021] Furthermore, it also includes a back pressure valve, the oil outlet of which is connected to the oil tank, the oil inlet of which is connected to the oil outlet of the first relief valve and the oil outlet of the pilot pressure reducing valve, and the oil inlet of which is also connected to the return oil outlet of the first proportional directional valve, the second proportional directional valve, the first on / off directional valve and the second on / off directional valve.

[0022] This invention improves system stability by adding a back pressure valve to increase the return oil resistance.

[0023] Furthermore, it also includes a second overflow valve, the oil inlet of which is connected to the oil outlet of the third shuttle valve, and the oil outlet of the second overflow valve is connected to the oil tank.

[0024] This invention prevents damage to the oil supply pump caused by excessive load pressure by setting an overflow valve 2.

[0025] As can be seen from the above technical solutions, this utility model has the following advantages:

[0026] This invention provides an electrically controlled leveling valve assembly for a grader and a hydraulic system for an all-wheel-drive grader. By setting pilot valve one and pilot valve two, the adjustment electrical signal of the blade is converted into a pressure signal of the pilot valve, which is then converted into a flow signal of the proportional directional valve. This achieves electrically controlled leveling by the vehicle controller, eliminating manual operation and achieving a high level of automation and accuracy. A pilot pressure reducing valve lowers the pilot oil pressure, preventing damage to pilot valves one and two due to excessive pressure. A pilot relief valve prevents damage to pilot valves one and two, as well as proportional directional valves one and two, due to excessive pilot oil pressure. Shuttle valves one and two can output the larger load signal from the two proportional directional valves to meet the working needs of the lifting cylinder with a larger load. By using a load-sensitive variable pump as the oil supply pump and setting shuttle valves three and four, as well as an electrically controlled leveling valve assembly for the grader with shuttle valves one and two, the flow rate of the oil supply pump can be accurately and timely adjusted to ensure the left front wheel travels smoothly. The system addresses the maximum load requirements of the travel motor, right front wheel travel motor, left lifting cylinder, and right lifting cylinder. Simultaneously, through the actions of compensation valves one, two, three, and four, it maintains a constant pressure difference between the inlet and outlet of the corresponding directional valves, ensuring that the flow rate through the valves does not fluctuate with changes in adjusted load pressure. The relief valve one ensures that the main oil circuit's supply pressure remains within a safe range, preventing damage to working components such as the travel motor from excessive pressure. The two-position three-way solenoid valve one allows adjustment of the displacement of the left and right front wheel travel motors, achieving precise control of the motor's mechanical motion (such as speed, torque, and power). The two-position three-way solenoid valve two allows the travel motors to rotate freely without hydraulic drive force, meeting the actual needs of the equipment in transportation, maintenance, and emergency handling scenarios, and preventing mechanical failures or operational risks due to motor lock-up. The back pressure valve increases return oil resistance, improving system stability. The relief valve two prevents damage to the oil supply pump from excessive load pressure. Attached Figure Description

[0027] To more clearly illustrate the technical solution of this utility model, the drawings used in the description will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 This is a diagram of the hydraulic system according to a specific embodiment of the present invention.

[0029] Figure 2 This is a diagram of the hydraulic system according to the second specific embodiment of this utility model.

[0030] Figure 3This is a hydraulic system diagram of the electrically controlled leveling valve group and the switching directional valve one, switching directional valve two, pilot valve four, and pilot valve three used in the second specific embodiment of this utility model for a grader.

[0031] In the diagram: 1. Oil tank; 2. Oil supply pump; 3. Back pressure valve; 4. Relief valve 1; 5. Pilot pressure reducing valve; 6. Pilot relief valve; 7. Two-position three-way solenoid valve 1; 8. Two-position three-way solenoid valve 2; 9. Left front wheel travel motor; 10. Right front wheel travel motor; 11. Left lifting cylinder; 12. Right lifting cylinder; 13. Pilot valve 3; 14. Pilot valve 4; 15. Electrically controlled leveling valve assembly for graders; 16. Compensating valve 3; 17. Compensating valve 4; 19. Pilot valve 1; 20. Pilot valve 2; 21. Proportional directional valve 2; 22. Shuttle valve 2; 23. Shuttle valve 1; 24. Compensating valve 2; 25. Compensating valve 1; 26. Proportional directional valve 1; 27. Switching directional valve 2; 28. Switching directional valve 1; 29. ​​Relief valve 2. Detailed Implementation

[0032] To make the objectives, features, and advantages of this utility model more apparent and understandable, the technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings of the specific embodiments. Obviously, the embodiments described below are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this patent, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this patent. Specific Implementation Method 1

[0034] like Figure 1As shown in the figure, this specific embodiment provides an electrically controlled leveling valve assembly for a grader, including a proportional directional valve 26, a proportional directional valve 21, a pilot valve 19, and the pilot valve 20. The oil inlet of the proportional directional valve 26 can be connected to the oil supply pump 2 through a compensation valve 25. The oil inlets of the proportional directional valve 21 can also be connected to the oil supply pump 2. The oil outlet of the proportional directional valve 26 can be connected to the left lifting cylinder 11, and the oil outlet of the proportional directional valve 21 can be connected to the right lifting cylinder 12. The electrical signal interfaces of the pilot valve 19 and the pilot valve 20 can both be electrically connected to the grader controller. The oil inlets of the pilot valve 19 and the pilot valve 20 can also be connected to the oil supply pump 2. Pump 2 is connected. The oil outlet of pilot valve 19 is connected to the control oil port of proportional directional valve 26, and the oil outlet of pilot valve 20 is connected to the control oil port of proportional directional valve 21. In this specific embodiment, the return oil port of left lifting cylinder 11 is connected to the return oil inlet of proportional directional valve 26, and the return oil outlet of proportional directional valve 26 is connected to oil tank 1. The oil outlet of proportional directional valve 21 is connected to the inlet of right lifting cylinder 12, and the return oil port of right lifting cylinder 12 is connected to the return oil inlet of proportional directional valve 21. The return oil outlet of proportional directional valve 21 is connected to oil tank 1. Each of the main valve cores of proportional directional valve 26 and proportional directional valve 21 has a control oil chamber (A). (A) and (B), the pilot oil enters different oil chambers through the switching of the corresponding pilot valves, realizing bidirectional movement of the valve core (e.g., the valve core moves to the right when oil enters chamber A, and moves to the left when oil enters chamber B); after this setting, pilot valve 19 and pilot valve 20 convert the electrical signal of the controller into the pressure signal of the hydraulic oil. The pilot oil flowing to pilot valve 19 and pilot valve 20 is output with the corresponding pressure and enters the control oil port of proportional directional valve 16 and proportional directional valve 21. In the control oil chamber of proportional directional valve 16 and proportional directional valve 21, the valve core is pushed to move in the corresponding direction and displacement, thereby realizing flow control, so that the displacement of the left lifting cylinder 11 and the right lifting cylinder 12 can be automatically and accurately adjusted.

[0035] This specific embodiment converts the adjustment electrical signal of the blade into pressure signals of the pilot valves 19 and 20, and then into flow signals of the corresponding proportional directional valves, thereby achieving electronically controlled leveling. Compared with the prior art, where the operator provides signals to the multi-way valves by operating the pilot handle, manual operation is eliminated. There is no need for manual judgment of the relationship between the position, hydraulic signals, and the movement of the pilot handle. The leveling has a high level of automation and high accuracy.

[0036] like Figure 2 and Figure 3As shown, preferably, the oil inlets of the pilot valve 19 and the pilot valve 20 are respectively connected to the oil outlet of the pilot pressure reducing valve 5, and the oil inlet of the pilot pressure reducing valve 5 can be connected to the oil supply pump 2; by setting the pilot pressure reducing valve 5 to reduce the pilot oil pressure, damage to the pilot valve 19 and the pilot valve 20 due to excessive pressure is avoided.

[0037] To avoid damage to components due to excessive pilot oil pressure, such as Figure 2 and Figure 3 As shown, in this specific embodiment, the oil outlet of the pilot pressure reducing valve 5 is also connected to the oil inlet of the pilot relief valve 6, and the oil outlet of the pilot relief valve 6 can be connected to the oil tank 1. With this setting, when the pilot oil circuit pressure exceeds the pressure threshold of the pilot relief valve 6, the pilot relief valve 6 opens and directly guides the pilot oil back to the oil tank 1, avoiding it from entering the pilot valve 19 and the pilot valve 20.

[0038] In order to ensure that the output flow of the vehicle's hydraulic system meets the maximum load requirements of this leveling valve assembly, such as Figure 1 As shown, in this specific embodiment, it also includes shuttle valve 1 23 and shuttle valve 22. The two oil inlets of shuttle valve 22 are respectively connected to the oil tank 1 and the load-sensitive port of proportional directional valve 21. The oil outlet of shuttle valve 22 is connected to one oil inlet of shuttle valve 1 23. The other oil inlet of shuttle valve 1 23 is connected to the load-sensitive port of proportional directional valve 1 26. The oil inlet of proportional directional valve 1 26 can be connected to the oil supply pump 2 through compensation valve 1 25. The oil inlet of proportional directional valve 21 can be connected to the oil supply pump 2 through compensation valve 2 24. With this configuration, the larger load signal of the two proportional directional valves can be output through the synergistic action of shuttle valve 1 23 and shuttle valve 2 22, so that the adjustment of the output flow of the vehicle hydraulic system meets the maximum load requirement of this leveling valve group. The other proportional directional valve with a smaller load is kept working normally through the action of compensation valve 1 25 and compensation valve 2 24. In this specific embodiment, both compensation valve 1 25 and compensation valve 2 24 are pressure compensation valves.

[0039] The process of the grader automatically adjusting the blade position is as follows:

[0040] One or more GNSS antennas are installed on the blade or other parts of the grader. These antennas receive navigation signals from satellites to obtain the grader's position information, including longitude, latitude, and elevation. The grader is also equipped with various other sensors to help determine the blade's attitude. The grader establishes a coordinate system with a fixed point or plane as a reference. It uses a GNSS receiver to receive and process the signals from the GNSS antennas, calculates the position of the GNSS antenna phase center, and combines the angle and displacement information measured by the sensors. Through specific algorithms and formulas, it calculates the blade's position vector and attitude information in the coordinate system, including the blade's lifting height, tilt angle, and lateral displacement. The calculated actual position and attitude of the blade are compared with the pre-set target position and attitude to obtain the deviation. The target position and attitude information can come from a digital work site model or be a set value input by the operator on the control interface according to the work requirements. The controller calculates the direction and magnitude of adjustment required based on the deviation and generates corresponding control signals. The control signals are transmitted to the leveling valve group to drive the corresponding lifting cylinder to perform the action.

[0041] The working process of this electrically controlled leveling valve assembly is as follows:

[0042] When the blade height needs to be adjusted, hydraulic oil reaches compensation valve 25 and compensation valve 24 via oil supply pump 2. Simultaneously, pilot valve 19 and pilot valve 20 receive corresponding electrical signals and output pilot hydraulic oil at a certain pressure. This drives the valve cores of proportional directional valve 26 and proportional directional valve 21 to move a corresponding distance in the corresponding direction, causing compensation valve 25 and compensation valve 24 to connect with the inlets of proportional directional valve 26 and proportional directional valve 21, respectively, thus enabling proportional directional control. The return oil outlets of valve 1 (26) and proportional directional valve 2 (21) are connected to oil tank 1. The oil enters the inlet of the left lifting cylinder 11 and / or the right lifting cylinder 12 respectively, and then flows back to oil tank 1 from the outlet of the left lifting cylinder 11 and / or the right lifting cylinder 12, thereby realizing the adjustment of the blade. When the blade height does not need to be adjusted, the valve cores of proportional directional valve 1 (26) and proportional directional valve 2 (21) are in the neutral position, the hydraulic oil cannot reach the left lifting cylinder 11 and the right lifting cylinder 12, and the blade does not move. Specific Implementation Method Two

[0044] like Figure 2As shown, this specific embodiment provides a hydraulic system for an all-wheel drive grader, including an oil tank 1, an oil supply pump 2, a left lifting cylinder 11, a right lifting cylinder 12, a left front wheel travel motor 9, and a right front wheel travel motor 10. It also includes an electrically controlled leveling valve assembly 15 for the grader as described in Specific Embodiment 1. The left front wheel travel motor 9 is connected to the oil supply pump 2 and the oil tank 1 via a first switching directional valve 28. The first switching directional valve 28 can adjust the start, stop, and direction of the left front wheel travel motor 9. The oil inlet of the first switching directional valve 28 is connected to the oil supply pump 2 via a third compensation valve 16, which is a pressure compensation valve. The right front wheel travel motor 10 is connected to the oil supply pump 2 and the oil tank 1 via a second switching directional valve 27. The switch directional valve 27 can adjust the start, stop, and steering of the right front wheel travel motor 10. The oil inlet of the switch directional valve 27 is connected to the oil supply pump 2 through the compensation valve 4 17, which is a pressure compensation valve. The oil supply pump 2 is a load-sensitive variable pump. The oil outlet of the shuttle valve 1 23 is connected to one oil inlet of the shuttle valve 4 31. The other oil inlet of the shuttle valve 4 31 is connected to the load-sensitive port of the switch directional valve 27. The oil outlet of the shuttle valve 4 31 is connected to one oil inlet of the shuttle valve 3 30. The other oil inlet of the shuttle valve 3 30 is connected to the load-sensitive port of the switch directional valve 1 28. The oil outlet of the shuttle valve 3 30 is connected to the control oil port of the oil supply pump 2.

[0045] This specific embodiment uses a load-sensitive variable pump as the oil supply pump 2, and sets up shuttle valve three, shuttle valve four, and an electronically controlled leveling valve group 15 for the grader with shuttle valve one 23 and shuttle valve two 22. This allows for accurate and timely adjustment of the flow rate of the oil supply pump 2, ensuring that the maximum load requirements of the left front wheel travel motor 9, right front wheel travel motor 10, left lifting cylinder 11, and right lifting cylinder 12 are met. At the same time, through the action of compensation valve one 25, compensation valve two 24, compensation valve three 16, and compensation valve four 17, the pressure difference between the inlet and outlet of the corresponding directional valve is kept constant, ensuring that the pressure through the corresponding directional valve does not fluctuate with the change in hydraulic oil flow rate after adjustment.

[0046] As a preferred option, such as Figure 2 and Figure 3 As shown, in this specific embodiment, an overflow valve 4 is also included. The oil inlet of the overflow valve 4 can be connected to the oil supply pump 2, and the oil outlet of the overflow valve 4 can be connected to the oil tank 1. By setting the overflow valve 4, the oil supply pressure of the main oil circuit can be ensured to be within a safe range, and excessive pressure can be avoided to prevent damage to the working components such as the travel motor on the main oil circuit. In this specific embodiment, the overflow valve 4 is a pilot overflow valve.

[0047] In this specific embodiment, pilot valve three 13 and pilot valve four 14 are also included. Pilot valve three 13 and pilot valve four 14 are electrically connected to the controller. The oil inlet of pilot valve three 13 and pilot valve four 14 is connected to the oil outlet of pilot pressure reducing valve 5. The oil outlet of pilot valve three 13 is connected to the control oil port of switch reversing valve one 28. The oil outlet of pilot valve four 14 is connected to the control oil port of switch reversing valve two 27.

[0048] To meet the needs of various working conditions, such as Figure 2 As shown, this specific embodiment also includes a two-position three-way solenoid valve 7 and a two-position three-way solenoid valve 8. The electrical signal interfaces of both the two-position three-way solenoid valve 7 and the two-position three-way solenoid valve 8 are electrically connected to the controller. The oil inlets of both the two-position three-way solenoid valve 7 and the two-position three-way solenoid valve 8 are connected to the oil supply pump 2. The oil return ports of both the two-position three-way solenoid valve 7 and the two-position three-way solenoid valve 8 are connected to the oil tank 1. The oil outlet of the two-position three-way solenoid valve 7 is connected to the displacement control ports of the left front wheel travel motor 9 and the right front wheel travel motor 10, respectively. The oil outlet of the two-way solenoid valve 8 is connected to the free wheel oil supply ports of the left front wheel travel motor 9 and the right front wheel travel motor 10, respectively. The displacement of the left front wheel travel motor 9 and the right front wheel travel motor 10 can be adjusted through the two-position three-way solenoid valve 7, so as to achieve precise control of the mechanical motion state of the motor (such as speed, torque and power) and meet the working needs under various working conditions. The two-position three-way solenoid valve 8 can make the travel motor rotate freely without the application of hydraulic driving force, so as to meet the actual needs of the equipment in the scenarios of transportation, maintenance and emergency handling, and avoid mechanical failure or operational risks caused by the travel motor locking.

[0049] As a preferred option, such as Figure 2 As shown, this specific embodiment also includes a back pressure valve 3. The oil outlet of the back pressure valve 3 is connected to the oil tank 1, and the oil inlet of the back pressure valve 3 is connected to the oil outlet of the overflow valve 4 and the oil outlet of the pilot pressure reducing valve 5. The oil inlet of the back pressure valve 3 is also connected to the return oil outlet of the proportional directional valve 26, the proportional directional valve 21, the switch directional valve 28, and the switch directional valve 27. By setting the back pressure valve 3, the return oil resistance can be increased to improve the system stability.

[0050] like Figure 2 As shown, this specific embodiment also includes a second overflow valve 29, the oil inlet of which is connected to the oil outlet of the fourth shuttle valve, and the oil outlet of the second overflow valve 29 is connected to the oil tank 1; by setting the second overflow valve 29, damage to the oil supply pump 2 is avoided due to excessive load pressure.

[0051] The working process of the hydraulic system of this all-drive grader is as follows:

[0052] Hydraulic oil in tank 1 is pumped by oil supply pump 2 to compensation valves 1-25, 2-24, 3-16, and 4-17. Pilot valves 1-19, 2-20, 3-13, and 4-14 output pilot oil of corresponding pressure according to the electrical signal given by the controller. The pilot oil drives the valve cores of proportional directional valves 1-26, 2-21, 1-28, and 2-27 to perform corresponding actions. The hydraulic oil in compensation valves 1-25, 2-24, 3-16, and / or 4-17 enters the front left wheel travel motor, front right wheel travel motor, left lifting cylinder 11, or right lifting cylinder 12 through the corresponding directional valves. If necessary, 2-position 3-way solenoid valve 7 adjusts the displacement of the front left wheel travel motor and the front right wheel travel motor according to the signal from the controller. 2-position 3-way solenoid valve 8 allows the travel motor to rotate freely without hydraulic driving force according to the signal from the controller.

[0053] As can be seen from the above specific embodiments, this utility model has the following beneficial effects:

[0054] 1. By setting pilot valve 19 and pilot valve 20, the adjustment electrical signal of the blade is converted into the pressure signal of the pilot valve, and then into the flow signal of the proportional directional valve, so as to realize the electronic leveling of the whole vehicle controller, eliminating the need for manual operation and control, and achieving a high level of automation and high accuracy in leveling.

[0055] 2. By setting the pilot pressure reducing valve 5, the pilot oil pressure is reduced to avoid damage to the pilot valve 19 and pilot valve 20 due to excessive pressure.

[0056] 3. By setting the pilot relief valve 6, excessive pilot oil circuit pressure is prevented from causing damage to pilot valve 19, pilot valve 20, proportional directional valve 1 26, and proportional directional valve 21.

[0057] 4. By setting shuttle valve 1 23 and shuttle valve 2 22, the larger load signal of the two proportional directional valves can be output to meet the working needs of the lifting cylinder with a larger load.

[0058] 5. By using a load-sensitive variable pump as the oil supply pump 2, and setting up shuttle valve 30, shuttle valve 4 31, and an electronically controlled leveling valve group 15 for the grader with shuttle valve 1 23 and shuttle valve 2 22, the flow rate of the oil supply pump 2 can be accurately and timely adjusted to ensure that the maximum load requirements of the left front wheel travel motor 9, right front wheel travel motor 10, left lifting cylinder 11, and right lifting cylinder 12 are met. At the same time, through the action of compensation valve 1 25, compensation valve 2 24, compensation valve 3 16, and compensation valve 4 17, the pressure difference between the inlet and outlet of the corresponding reversing valve is kept constant, ensuring that the flow rate through the valve does not fluctuate with the change of the adjusted load pressure.

[0059] 6. By setting the overflow valve 4, the oil supply pressure of the main oil circuit can be kept within a safe range, avoiding damage to the working components such as the travel motor on the main oil circuit due to excessive pressure.

[0060] 7. The displacement of the left front wheel travel motor 9 and the right front wheel travel motor 10 can be adjusted by the two-position three-way solenoid valve 7, so as to achieve precise control of the mechanical motion state of the motor (such as speed, torque and power). The two-position three-way solenoid valve 8 can make the travel motor rotate freely without the application of hydraulic driving force, so as to meet the actual needs of the equipment in the scenarios of transportation, maintenance and emergency handling, and avoid mechanical failure or operational risks caused by motor lock-up.

[0061] 8. By setting back pressure valve 3, the return oil resistance can be increased, thus improving system stability;

[0062] 9. By setting the overflow valve 29, damage to the oil supply pump 2 can be avoided due to excessive load pressure.

[0063] The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An electrically controlled grading valve group for a grader, comprising a proportional directional valve one (26) and a proportional directional valve two (21), an oil inlet of each of the proportional directional valve one (26) and the proportional directional valve two (21) being able to communicate with an oil supply pump (2), an oil outlet of the proportional directional valve one (26) being able to communicate with a left lift cylinder (11), and an oil outlet of the proportional directional valve two (21) being able to communicate with a right lift cylinder (12), characterized in that, It also includes pilot valve one (19) and pilot valve two (20). The electrical signal interfaces of pilot valve one (19) and pilot valve two (20) can be electrically connected to the grader controller. The oil inlets of pilot valve one (19) and pilot valve two (20) can be connected to the oil supply pump (2). The oil outlet of pilot valve one (19) is connected to the control oil port of proportional directional valve one (26). The oil outlet of pilot valve two (20) is connected to the control oil port of proportional directional valve two (21).

2. The electronically controlled grade valve pack for a motor grader of claim 1, wherein, The inlets of the first pilot valve (19) and the second pilot valve (20) are respectively connected to the outlet of the pilot pressure reducing valve (5), and the inlet of the pilot pressure reducing valve (5) can be connected to the oil supply pump (2).

3. The electrically controlled leveling valve assembly for a grader as described in claim 2, characterized in that, The oil outlet of the pilot pressure reducing valve (5) is also connected to the oil inlet of the pilot relief valve (6), and the oil outlet of the pilot relief valve (6) can be connected to the oil tank (1).

4. The electrically controlled leveling valve assembly for a grader as described in claim 3, characterized in that, It also includes shuttle valve one (23) and shuttle valve two (22). The two oil inlets of shuttle valve two (22) are respectively connected to the oil tank (1) and the load sensitive port of the proportional directional valve two (21). The oil outlet of shuttle valve two (22) is connected to one oil inlet of shuttle valve one (23). The other oil inlet of shuttle valve one (23) is connected to the load sensitive port of the proportional directional valve one (26). The oil inlet of the proportional directional valve one (26) can be connected to the oil supply pump (2) through compensation valve one (25). The oil inlet of the proportional directional valve two (21) can be connected to the oil supply pump (2) through compensation valve two (24).

5. A hydraulic system for an all-wheel drive grader, comprising an oil tank (1), an oil supply pump (2), a left lifting cylinder (11), a right lifting cylinder (12), a left front wheel travel motor (9), and a right front wheel travel motor (10), characterized in that, It also includes the electrically controlled leveling valve assembly (15) for a grader as described in claim 4, wherein the left front wheel travel motor (9) is connected to the oil pump (2) and the oil tank (1) via a switching directional valve one (28), the oil inlet of the switching directional valve one (28) is connected to the oil pump (2) via a compensation valve three (16), the right front wheel travel motor (10) is connected to the oil pump (2) and the oil tank (1) via a switching directional valve two (27), and the oil inlet of the switching directional valve two (27) is connected to the oil pump (2) via a compensation valve four (17). 2) Connected, the oil supply pump (2) is a load-sensitive variable pump, the oil outlet of shuttle valve one (23) is connected to one oil inlet of shuttle valve four (31), the other oil inlet of shuttle valve four (31) is connected to the load-sensitive port of switch reversing valve two (27), the oil outlet of shuttle valve four (31) is connected to one oil inlet of shuttle valve three (30), the other oil inlet of shuttle valve three (30) is connected to the load-sensitive port of switch reversing valve one (28), and the oil outlet of shuttle valve three (30) is connected to the control oil port of the oil supply pump (2).

6. The hydraulic system of the all-drive grader as described in claim 5, characterized in that, It also includes an overflow valve (4), the oil inlet of which can be connected to the oil supply pump (2), and the oil outlet of which can be connected to the oil tank (1).

7. The hydraulic system of the all-drive grader as described in claim 6, characterized in that, It also includes pilot valve three (13) and pilot valve four (14), which are electrically connected to the controller. The oil inlet of the pilot valve three (13) and the pilot valve four (14) are connected to the oil outlet of the pilot pressure reducing valve (5). The oil outlet of the pilot valve three (13) is connected to the control oil port of the switch reversing valve one (28). The oil outlet of the pilot valve four (14) is connected to the control oil port of the switch reversing valve two (27).

8. The hydraulic system of the all-drive grader as described in claim 7, characterized in that, It also includes a two-position three-way solenoid valve one (7) and a two-position three-way solenoid valve two (8). Both the two-position three-way solenoid valve one (7) and the two-position three-way solenoid valve two (8) are electrically connected to the controller. The oil inlet of both the two-position three-way solenoid valve one (7) and the two-position three-way solenoid valve two (8) is connected to the oil supply pump (2). The oil return port of both the two-position three-way solenoid valve one (7) and the two-position three-way solenoid valve two (8) is connected to the oil tank (1). The oil outlet of the two-position three-way solenoid valve one (7) is connected to the displacement control port of the left front wheel travel motor (9) and the right front wheel travel motor (10) respectively. The oil outlet of the two-position three-way solenoid valve two (8) is connected to the free wheel oil supply port of the left front wheel travel motor (9) and the right front wheel travel motor (10) respectively.

9. The hydraulic system of the all-drive grader as described in claim 8, characterized in that, It also includes a back pressure valve (3), the oil outlet of which is connected to the oil tank (1), the oil inlet of which is connected to the oil outlet of the first overflow valve (4) and the oil outlet of the pilot pressure reducing valve (5), and the oil inlet of the back pressure valve (3) is also connected to the oil return outlet of the first proportional directional valve (26), the second proportional directional valve (21), the first switch directional valve (28) and the second switch directional valve (27).

10. The hydraulic system of the all-drive grader as described in claim 9, characterized in that, It also includes a second overflow valve (29), the oil inlet of which is connected to the oil outlet of the third shuttle valve (30), and the oil outlet of the second overflow valve (29) is connected to the oil tank (1).

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