Grader Walking System Control Strategy and Grader Walking System

Abstract

This invention relates to the field of engineering machinery technology, specifically disclosing a control strategy and system for a grader's walking system. The system includes an oil tank, a front-wheel drive module, and a rear-wheel drive module. The front-wheel drive module includes a make-up oil pump, two corresponding travel pumps, two freewheel valves, and two motor assemblies. The freewheel valves have three states: free, driven, and transition. In the free state, the inlet and outlet of the motor assemblies are connected to the oil tank. In the driven state, the travel pumps and motor assemblies form a closed hydraulic circuit. In the transition state, the inlet of the make-up oil pump is simultaneously connected to the inlet and outlet of the motor assemblies. When executing the mode switching control strategy, when the front-wheel drive module intervenes, it ensures the vehicle is in neutral and the vehicle speed V < vkm / h. The freewheel valves are first modulated into the transition state, directing the make-up oil pressure to both sides of the hydraulic motors to reduce impact. This improves the stability of the grader's walking system.

Description

Technical Field

[0001] This invention relates to the field of engineering machinery technology, and in particular to the control strategy of the grader's walking system and the grader's walking system. Background Technology

[0002] A grader is an earthmoving machine that uses a scraper to level the ground. The scraper is mounted between the front and rear axles and can be raised, lowered, tilted, rotated, and extended. It operates flexibly and accurately, is easy to operate, and provides high precision in leveling the ground. It is suitable for constructing roadbeds and pavements, building slopes, excavating ditches, mixing road mixtures, clearing snow, pushing loose materials, and maintaining dirt and gravel roads.

[0003] Most motor graders are currently rear-wheel drive with the front wheels being passive, although some are all-wheel drive. Rear-wheel drive motor graders are only suitable for a limited range of working conditions, and increasingly more applications require power from the front wheels. Therefore, all-wheel drive motor graders are gaining popularity.

[0004] Existing all-wheel drive graders typically have hydraulically driven front wheels and mechanically driven rear wheels. When the grader starts in front drive mode, the sudden pressure change in the front wheel hydraulic system can easily cause hydraulic shock, damaging the front wheel hydraulic system and reducing the user experience of the grader.

[0005] Therefore, there is an urgent need for a control strategy and a proper grader walking system to solve the above problems. Summary of the Invention

[0006] The purpose of this invention is to provide a control strategy and a walking system for a motor grader, in order to solve the problem in the related technology that when the motor grader starts the front drive, the sudden change in pressure in the front wheel hydraulic system can easily lead to hydraulic shock, which damages the front wheel hydraulic system and reduces the user experience of the motor grader.

[0007] On the one hand, the present invention provides a control strategy for a grader walking system, which is applied to the grader walking system. The grader walking system includes an oil tank, a front wheel drive module and a rear wheel drive module. The front wheel drive module includes an oil replenishment pump and two walking pumps, two free wheel valves and two motor sets that correspond one-to-one with the three.

[0008] The grader's walking system control strategy includes a mode switching control strategy, which includes:

[0009] A10: Grader starts;

[0010] A20: Determine if a rear wheel independent drive command has been issued. If yes, execute A30; otherwise, execute A40.

[0011] A30: The free wheel valve is in a free state, the rear wheel drive module works independently, and the free state means that the oil inlet and oil outlet of the motor assembly are respectively connected to the oil tank;

[0012] A40: Determine if the speed of the grader V < vkm / h and it is in neutral. If yes, execute A50; otherwise, execute A30.

[0013] A50: The free wheel valve switches to the transition state, adjusts the displacement of the travel pump to match the actual vehicle speed, and after t seconds, switches to the drive state. The transition state is that the oil outlet of the oil replenishment pump is simultaneously connected to the oil inlet and outlet of the motor assembly. The drive state is that the travel pump and the motor assembly are connected to form a closed hydraulic circuit.

[0014] A60: Determine if a front wheel independent drive command has been issued. If yes, execute A70; otherwise, execute A80.

[0015] A70: The front-wheel drive module operates independently;

[0016] A80: The front-wheel drive module and the rear-wheel drive module work together.

[0017] As a preferred technical solution for the grader's walking system control strategy, the grader's walking system control strategy further includes a braking control strategy, which includes:

[0018] B10: Collect the braking signal of the grader;

[0019] B20: Determine if a brake signal is generated. If yes, execute B40; otherwise, execute B30.

[0020] B30: The freewheel valve is in the free state, execute B60;

[0021] B40: Determine if the vehicle is in all-wheel drive mode. If yes, execute B50; otherwise, execute B30.

[0022] B50: The pressure of the travel pump is reduced to the set pressure of the replenishing pump or slightly higher than the set pressure of the replenishing pump;

[0023] B60: The service braking module brakes the two rear wheels of the rear-wheel drive module and returns to B10.

[0024] As a preferred technical solution for the control strategy of the grader's walking system, the B50 further includes: the rate of decrease in the displacement of the walking pump is consistent with the rate of decrease in the overall vehicle speed.

[0025] As a preferred technical solution for the grader's walking system control strategy, the grader's walking system control strategy further includes a steering control strategy, which includes:

[0026] C10: Collect the position of the articulated steering cylinder of the articulated steering module and the position of the front wheel steering cylinder of the front wheel steering module;

[0027] C20: Determine whether the position of the articulated steering cylinder and / or the position of the front wheel steering cylinder has changed. If yes, execute C30; otherwise, execute C10.

[0028] C30: Calculate the speed deviation between the left and right front wheels and the displacement of the two travel pumps on the left and right sides;

[0029] C40: Adjust the displacement of the two traveling pumps according to the calculation results.

[0030] As a preferred technical solution for the control strategy of the grader's walking system, the steering control strategy further includes:

[0031] C50: Measure whether the actual speed of the two motor sets is within the calculated speed range. If yes, execute C10; otherwise, execute C60.

[0032] C60: Based on the deviation between the actual speed and the calculated speed of the two motor sets, adjust the calculation results of the left and right travel pumps, and return to C40.

[0033] As a preferred technical solution for the grader's walking system control strategy, the grader's walking system control strategy further includes a front-to-rear wheel power distribution control strategy, which includes:

[0034] D10: The grader is in all-wheel drive mode;

[0035] D20: Measure the front wheel load a and the rear wheel load b;

[0036] D30: Is the ratio of the front wheel load to the rear wheel load equal to a / b±c? If yes, then execute D40; otherwise, execute D50.

[0037] D40: Maintain current driving status;

[0038] D50: Adjust the displacement of the travel pump to synchronize the speed of the front and rear wheels.

[0039] As a preferred technical solution for the control strategy of the grader's walking system, the D50 specifically includes:

[0040] D501: Determine the relationship between the ratio R of the front wheel load to the rear wheel load and a / b±c. If R < a / b±c, then execute D502; if R > a / b±c, then execute D503.

[0041] D502: Adjusts the displacement of the travel pump to increase front wheel drive force.

[0042] D503: Adjusts the displacement of the travel pump to reduce the driving force of the front wheels.

[0043] On the other hand, the present invention provides a grader walking system, controlled by a grader walking system control strategy according to any of the above-mentioned solutions, including:

[0044] tank;

[0045] The front-wheel drive module includes two travel pumps, two freewheel valves, two motor assemblies, and a fuel replenishment pump. Each of the travel pumps, freewheel valves, and motor assemblies is connected in a one-to-one correspondence. The fuel replenishment pump's inlet is connected to the fuel tank, and the fuel replenishment pump's outlet is connected to the fuel tank. The fuel replenishment pump's displacement is less than the travel pump's displacement. The freewheel valves have three states: a free state, a driven state, and a transition state. In the free state, the travel pump's outlet and inlet are connected, and the motor assemblies' inlets and outlets are respectively connected to the fuel tank. In the driven state, the travel pump's outlet is connected to the motor assemblies' inlets, and the motor assemblies' outlet is connected to the travel pump's inlet. In the transition state, the travel pump's outlet and inlet are connected, and the motor assemblies' inlets and outlets are simultaneously connected to the fuel replenishment pump's outlet.

[0046] The rear-wheel drive module can work synchronously with the front-wheel drive module or work independently.

[0047] A service braking module, which is used to brake the two rear wheels of the rear wheel drive module;

[0048] The grader includes an articulated steering module and a front wheel steering module, wherein the articulated steering cylinder of the articulated steering module and the front wheel steering cylinder of the front wheel steering module are capable of controlling the steering of the grader.

[0049] As a preferred technical solution for the grader's walking system, the motor assembly includes a first valve, a first motor, and a second motor. The first port of the first valve serves as the oil inlet of the motor assembly, the second port of the first valve serves as the oil outlet of the motor assembly, the third port of the first valve is connected to the oil inlet of the first motor, the fourth port of the first valve is connected to the oil inlet of the second motor, and the oil outlets of the first motor and the second motor are connected to the fifth port of the first valve. The first valve includes a first position a and a second position a. At the first position a, the first port of the first valve is connected to both the third and fourth ports of the first valve, and the second port is connected to the fifth port. At the second position a, the first port of the first valve is connected to the third port of the first valve, and the second port of the first valve is connected to both the fourth and fifth ports of the first valve.

[0050] As a preferred technical solution for the grader walking system, the first valve includes a first valve body, a first valve core and a first return spring. The first valve core is slidably disposed in the first valve body. The first valve body is provided with a first control oil port. The first control oil port of the first valve body is located on one side of the first valve core. The first return spring is disposed in the first valve body and located on the other side of the first valve core.

[0051] The front-wheel drive module also includes a speed control valve. The first interface of the speed control valve is connected to the oil outlet of the oil replenishment pump, the second interface of the speed control valve is connected to the oil tank, and the third interface of the speed control valve is connected to the control oil port of the first valve. The speed control valve includes a first position b and a second position b. At the first position b, the first interface and the third interface of the speed control valve are connected. At the second position b, the second interface and the third interface of the speed control valve are connected.

[0052] The beneficial effects of this invention are as follows:

[0053] This invention provides a control strategy and a motor grader walking system for a motor grader. The motor grader walking system includes an oil tank, a front-wheel drive module, and a rear-wheel drive module. The front-wheel drive module includes a supplementary oil pump, two corresponding travel pumps, two free wheel valves, and two motor sets. The oil inlet of the supplementary oil pump and the oil inlet of the travel pump are respectively connected to the oil tank. The displacement of the supplementary oil pump is smaller than that of the travel pump. The free wheel valves include a free state, a driven state, and a transition state. In the free state, the oil inlet and outlet of the motor sets are respectively connected to the oil tank. In the driven state, the travel pumps and motor sets are connected to form a closed hydraulic circuit. In the transition state, the oil outlet of the supplementary oil pump is simultaneously connected to the oil inlet and outlet of the motor sets. When the freewheel valve is in the free state, both the inlet and outlet of the motor unit are connected to the oil tank, allowing the two front wheels to rotate freely. When the freewheel valve is in the driven state, the travel pump drives the hydraulic fluid to flow in the closed hydraulic circuit formed by the travel pump and the motor unit, thereby enabling the motor unit to drive the corresponding front wheels to rotate. When the freewheel valve is in the transition state, the replenishing pump pumps the oil from the oil tank into both the inlet and outlet of the motor unit simultaneously, ensuring that the motor unit maintains a certain pressure while still rotating as the grader moves.

[0054] When executing the mode switching control strategy, after the grader starts and a rear-wheel independent drive command is detected, the freewheel valve is adjusted to the free state. This allows the two front wheels of the front-wheel drive module to rotate together with the two rear wheels of the rear-wheel drive module, thus avoiding interference with the operation of the rear-wheel drive module. If no rear-wheel independent drive command is detected, it indicates that the grader is about to activate either front-wheel independent drive mode or all-wheel drive mode. Both modes require the front-wheel drive module to operate. If front-wheel drive is engaged during vehicle movement, the pressure in the motor housing will be too high, exceeding the allowable value and adversely affecting the motor's lifespan. Therefore, this operation is not allowed in the program; the vehicle must be in neutral and the speed V < v km / h. To prevent a direct switch from low pressure to high pressure within the motor housing, the freewheel valve is first adjusted to a transition state, directing the replenishment pressure to both sides of the hydraulic motor to reduce impact. Simultaneously, by adjusting the travel pump displacement to match the actual vehicle speed, and then switching to the aforementioned drive state after t seconds, the motor assembly can be pre-filled with replenishing oil pressure. When high-pressure oil is supplied to the motor assembly's oil inlet, the impact caused by directly supplying high pressure to the motor assembly is avoided. This improves the stability of the grader's travel system and enhances the driver's experience. Attached Figure Description

[0055] Figure 1 This is a transmission route diagram of the grader's walking system in an embodiment of the present invention;

[0056] Figure 2 This is a hydraulic circuit diagram of the grader's walking system in an embodiment of the present invention;

[0057] Figure 3 This is a hydraulic circuit diagram showing the free wheel valve in the free state of the motor grader's walking system in an embodiment of the present invention;

[0058] Figure 4 This is a hydraulic circuit diagram showing the free wheel valve in the driving state of the motor grader walking system in an embodiment of the present invention;

[0059] Figure 5 This is a hydraulic circuit diagram showing the freewheel valve in the transition state of the motor grader's walking system in an embodiment of the present invention;

[0060] Figure 6 This is a flowchart of the mode switching control strategy of the grader walking system in an embodiment of the present invention;

[0061] Figure 7 This is a flowchart of the braking control strategy of the grader walking system control strategy in an embodiment of the present invention;

[0062] Figure 8 This is a flowchart of the steering control strategy of the grader walking system control strategy in an embodiment of the present invention;

[0063] Figure 9 This is a flowchart of the front and rear wheel power distribution control strategy of the grader walking system in an embodiment of the present invention.

[0064] In the picture:

[0065] 1. Fuel tank;

[0066] 2. Front wheel drive module; 21. Oil replenishment pump; 22. Travel pump; 23. Freewheel valve; 231. Second valve; 232. Third valve; 24. Motor assembly; 241. First valve; 242. First motor; 243. Second motor; 25. Speed ​​control valve;

[0067] 3. Service brake module; 4. Articulated steering module; 41. Articulated steering cylinder; 5. Front wheel steering module; 51. Front wheel steering cylinder. Detailed Implementation

[0068] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0069] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The terms "first position" and "second position" refer to two different positions. Furthermore, "above," "on top of," and "over" the first feature in relation to the second feature includes the first feature directly above and diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "under," and "below" the first feature in relation to the second feature includes the first feature directly below and diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0070] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0071] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0072] like Figures 1-5As shown, this embodiment provides a grader walking system, including an oil tank 1, a front-wheel drive module 2, and a rear-wheel drive module. The front-wheel drive module 2 includes two walking pumps 22, two freewheel valves 23, two motor assemblies 24, and a make-up oil pump 21. The two walking pumps 22, two freewheel valves 23, and two motor assemblies 24 are in one-to-one correspondence. The oil inlet and outlet of the motor assembly 24 are simultaneously connected to the oil outlet of the make-up oil pump 21. The oil inlet of the make-up oil pump 21 is connected to the oil tank 1, and the make-up oil port of the walking pump 22 is connected to the oil tank 1. The displacement is less than that of the travel pump 22. The free wheel valve 23 includes a free state, a driven state, and a transition state. In the free state, the oil outlet and oil inlet of the travel pump 22 are connected, and the oil inlet and oil outlet of the motor assembly 24 are respectively connected to the oil tank 1. In the driven state, the oil outlet of the travel pump 22 is connected to the oil inlet of the motor assembly 24, and the oil outlet of the motor assembly 24 is connected to the oil inlet of the travel pump 22. In the transition state, the oil outlet and oil inlet of the travel pump 22 are connected. The rear wheel drive module works synchronously with the front wheel drive module 2 or works independently.

[0073] When the freewheel valve 23 is in the free state, both the oil inlet and outlet of the motor assembly 24 are connected to the oil tank 1, allowing the two front wheels to rotate freely. When the freewheel valve 23 is in the driven state, the travel pump 22 drives the oil to flow in the closed hydraulic circuit formed by the travel pump 22 and the motor assembly 24, thereby enabling the motor assembly 24 to drive the corresponding front wheel to rotate. When the freewheel valve 23 is in the transition state, the replenishing pump 21 pumps the oil from the oil tank 1 into both the oil inlet and outlet of the motor assembly 24 simultaneously, ensuring that the motor assembly 24 maintains a certain pressure while rotating with the movement of the grader.

[0074] Optionally, the motor assembly 24 includes a first valve 241, a first motor 242, and a second motor 243. The first port of the first valve 241 serves as the oil inlet of the motor assembly 24, the second port of the first valve 241 serves as the oil outlet of the motor assembly 24, the third port of the first valve 241 is connected to the oil inlet of the first motor 242, the fourth port of the first valve 241 is connected to the oil inlet of the second motor 243, and the oil outlets of the first motor 242 and the second motor 243 are connected to the fifth port of the first valve 241. The first valve 241 includes a first position a and a second position a. At the first position a, the first port of the first valve 241 is connected to the third and fourth ports of the first valve 241, and the second port is connected to the fifth port. At the second position a, the first port of the first valve 241 is connected to the third port of the first valve 241, and the second port of the first valve 241 is connected to the fourth and fifth ports of the first valve 241. In this embodiment, at the first position a of the first valve 241, the oil inlet of the motor assembly 24 passes through the first interface of the first valve 241 and then enters the first motor 242 and the second motor 243 through the third and fourth interfaces of the first valve 241, respectively. Simultaneously, the oil flowing out of the first motor 242 and the second motor 243 flows through the fifth and second interfaces of the first valve 241 to the oil outlet of the motor assembly 24. At the second position a of the first valve 241, the oil inlet of the motor assembly 24 passes through the first interface of the first valve 241 and then enters the first motor 242 through the third interface of the first valve 241. Simultaneously, the oil flowing out of the first motor 242 flows through the fifth and second interfaces of the first valve 241 to the oil outlet of the motor assembly 24. At this time, the oil outlet of the second motor 243 is connected to the fourth interface of the first valve 241, so the second motor 243 is in a free state.

[0075] Optionally, the first valve 241 can be controlled by comprising a first valve housing, a first valve core, and a first return spring. The first valve core is slidably disposed within the first valve housing. The first valve housing has a first control port located on one side of the first valve core. The first return spring is disposed within the first valve housing and located on the other side of the first valve core. In this embodiment, when high-pressure oil is introduced into the first control port of the first valve housing, the first valve core overcomes the elastic force of the first return spring and switches from the first position a to the second position a. When the high-pressure oil is discharged from the first control port of the first valve housing, the first valve core switches from the second position a to the first position a under the action of the elastic force of the first return spring.

[0076] The front-wheel drive module 2 also includes a speed control valve 25. The first port of the speed control valve 25 is connected to the outlet of the fuel pump 21, the second port of the speed control valve 25 is connected to the fuel tank 1, and the third port of the speed control valve 25 is connected to the control port of the first valve 241. The speed control valve 25 has a first position b and a second position b. In the first position b, the first port and the third port of the speed control valve 25 are connected. In the second position b, the second port and the third port of the speed control valve 25 are connected. In this embodiment, when the speed control valve 25 is in the first position b, the high-pressure oil from the fuel pump 21 enters the first control port of the first valve housing through the speed control valve 25. When the speed control valve 25 is in the second position b, the high-pressure oil from the first control port of the first valve housing flows back to the fuel tank 1 through the speed control valve 25.

[0077] Optionally, the speed control valve 25 is a solenoid valve.

[0078] Optionally, the freewheel valve 23 may include a second valve 231 and a third valve 232. The second valve 231 includes a second valve housing and a second valve core slidably disposed within the second valve housing. The oil outlet of the travel pump 22 is connected to the first oil port of the second valve housing, the second oil port of the second valve housing is connected to the oil inlet of the travel pump 22, the third oil port of the second valve housing is connected to the oil inlet of the motor assembly 24, the fourth oil port of the second valve housing is connected to the oil outlet of the motor assembly 24, and the fifth oil port of the second valve housing is selectively connected to the oil outlet of the replenishing pump 21 or the oil tank 1. The second valve core slides within the second valve housing, thereby allowing the second valve core to include a first position c and a second position c, with both the free state and the transition state being consistent with... The first position c of the second valve core corresponds to the driving state and the second position c of the second valve core. In the free state, the second valve core is located at the first position c of the second valve core. The first and second interfaces of the second valve housing are connected. The third, fourth, and fifth interfaces are interconnected. The fifth interface is connected to the oil tank 1. In the driving state, the second valve core is located at the second position c of the second valve core. The first and third interfaces of the second valve housing are connected. The second and fourth interfaces are connected. In the transition state, the second valve core is located at the first position c of the second valve core. The first and second interfaces of the second valve housing are connected. The third, fourth, and fifth interfaces are interconnected. The fifth interface is connected to the replenishing pump 21.

[0079] The second valve 231 also includes a second return spring, and the second valve housing also includes a first control port and a second control port. The first control port and the second return spring of the second valve housing are both located on one side of the second valve core, and the second port of the second valve housing is located on the other side of the second valve core.

[0080] The third valve 232 includes a third valve housing and a third valve core slidably disposed within the third valve housing. The first port of the third valve housing is connected to the oil outlet of the replenishing pump 21, the second port of the third valve housing is connected to the oil tank 1, the third port of the third valve housing is connected to the first control port of the second valve housing, and the fourth port of the third valve housing is connected to the fifth port and the second control port of the second valve housing, respectively. The third valve core includes a first position d, a second position d, and a third position d. When the third valve core is in the first position d, the first port and the fourth port of the third valve housing are connected, and the second port and the third port of the third valve housing are connected. When the third valve core is in the second position d, the first port of the third valve housing is blocked, and the second port of the third valve housing is connected to both the third and fourth ports of the third valve housing, respectively. When the third valve core is in the third position d, the second port of the third valve housing is blocked, and the first port of the third valve housing is connected to both the third and fourth ports of the third valve housing, respectively.

[0081] Optionally, the second valve 231 is a solenoid valve and the third valve 232 is a hydraulic control valve.

[0082] Optionally, in the rear-wheel drive module, the engine, gearbox, balance cable, and two rear wheels are sequentially connected to drive the rear wheels of the grader.

[0083] Optionally, the grader's walking system also includes a service brake module 3, which is used to brake the two rear wheels of the rear-wheel drive module.

[0084] Optionally, the grader's walking system also includes an articulated steering module 4 and a front wheel steering module 5, wherein the articulated steering cylinder 41 of the articulated steering module 4 and the front wheel steering cylinder 51 of the front wheel steering module 5 can control the grader's steering.

[0085] like Figure 6 As shown, the grader's walking system control strategy includes a mode switching control strategy, which includes:

[0086] A10: Grader starts;

[0087] A20: Determine if a rear wheel independent drive command has been issued. If yes, execute A30; otherwise, execute A40.

[0088] In this step, the operator can issue a separate drive command for the rear wheels by operating the control panel of the grader.

[0089] A30: Freewheel valve 23 is in the free state, and the rear wheel drive module works independently;

[0090] In this step, when the rear wheel independent drive command is detected, the free wheel valve 23 is adjusted to the free state so that the two front wheels of the front wheel drive module 2 can rotate together with the two rear wheels of the rear wheel drive module, so as to avoid affecting the operation of the rear wheel drive module.

[0091] A40: Determine if the grader speed V < vkm / h and is in neutral. If yes, execute A50; otherwise, execute A30.

[0092] In this step, if the vehicle engages front-wheel drive while in motion, the pressure on the motor assembly 24 housing will be high, exceeding the allowable value, which will adversely affect the motor's lifespan. Therefore, the program is set to disallow this operation, and the vehicle must be in neutral and the vehicle speed V < vkm / h. Specifically, the value of v is 0.5km / h-1km / h, preferably 0.5km / h.

[0093] A50: Free wheel valve 23 switches to transition state, adjusts the displacement of travel pump 22 to match the actual vehicle speed, and after t seconds, switches to drive state;

[0094] In this step, to prevent the motor assembly 24 from directly switching from low pressure to high pressure, the freewheel valve 23 is first adjusted to a transition state, directing the replenishing oil pressure to both sides of the hydraulic motor to reduce impact. Simultaneously, the displacement of the travel pump 22 is adjusted to match the actual vehicle speed. After t seconds, the drive state is switched back, allowing the motor assembly 24 to be pre-filled with replenishing oil pressure. When high-pressure oil is supplied to the oil inlet of the motor assembly 24, the impact caused by directly supplying high pressure to the motor assembly 24 is avoided. This improves the stability of the grader's travel system and enhances the driver's experience.

[0095] A60: Determine if a front wheel independent drive command has been issued. If yes, execute A70; otherwise, execute A80.

[0096] A70: Front-wheel drive module 2 operates independently;

[0097] A80: The front-wheel drive module 2 and the rear-wheel drive module work together.

[0098] like Figure 7 As shown, optionally, the grader's walking system control strategy also includes a braking control strategy, which includes:

[0099] B10: Collects the braking signal of the grader;

[0100] In this embodiment, the braking signal generated by the brake pedal is collected and analyzed.

[0101] B20: Determine if a brake signal is generated. If yes, execute B40; otherwise, execute B30.

[0102] In this step, the front wheels can only be braked via hydraulic circuit or disengaged from drive, while the rear wheels are braked by a brake caliper; that is, when the brake pedal is pressed, only the rear wheels brake. If the front wheel drive module 2 disengages from drive, the freewheel valve 23 needs to be adjusted to the free state; otherwise, the braking speeds of the front and rear wheels will be inconsistent. In this situation, if intermittent braking is applied, and the brake pedal is released, the front wheel drive module 2 will return to the drive state. At this time, the front wheel drive module 2 is constantly switching between the free state and the drive state, resulting in a poor driving experience and negatively impacting the lifespan of the hydraulic motor. Therefore, it is necessary to determine whether there is intermittent braking in the brake signal.

[0103] B30: Freewheel valve 23 is in the free state, execute B60.

[0104] In this step, if there is intermittent braking, the free wheel valve 23 needs to be switched to the free state, at which point the front wheel rotates along with the rear wheel.

[0105] B40: Determine if the vehicle is in all-wheel drive mode. If yes, execute B50; otherwise, execute B30.

[0106] B50: The pressure of the travel pump 22 is reduced to the set pressure of the oil replenishment pump 21 or slightly higher than the set pressure of the oil replenishment pump 21. The rate of decrease in the displacement of the travel pump 22 is consistent with the rate of decrease in the overall vehicle speed.

[0107] In this step, the pressure of the travel pump 22 is reduced to or slightly higher than the set pressure of the auxiliary pump 21, thus keeping the motor assembly 24 at a lower pressure. To ensure consistent braking speed between the front and rear wheels and prevent a sudden drop in the motor assembly 24 speed from causing dragging and cavitation, the rate of decrease in the displacement of the travel pump 22 is consistent with the rate of decrease in the overall vehicle speed. If the brake pedal is released, the all-wheel drive mode can continue because the freewheel valve 23 is in the driven state, protecting the motor and avoiding any impact on the front wheel drive module 2 during braking.

[0108] B60: Service brake module 3 brakes the two rear wheels of the rear-wheel drive module, then returns to B10.

[0109] like Figure 8 As shown, optionally, there is a steering angle deviation between the left and right front wheels. If this deviation is not corrected, the front wheels on one side will wear unevenly. To address this issue, the grader's travel system control strategy also includes a steering control strategy, which includes:

[0110] C10: Collect the position of articulated steering cylinder 41 and the position of front wheel steering cylinder 51;

[0111] C20: Determine whether the position of the articulated steering cylinder 41 and / or the position of the front wheel steering cylinder 51 has changed. If yes, execute C30; otherwise, execute C10.

[0112] This step is used to determine whether the grader has turned. Specifically, displacement sensors are installed on the articulated steering cylinder 41 and the front wheel steering cylinder 51. The displacement sensors calculate the grader's steering angle signal and transmit it to the vehicle controller.

[0113] C30: Calculate the speed deviation between the left and right front wheels and the displacement of the two left and right travel pumps (22).

[0114] In this step, the controller calculates the speed deviation between the left and right front wheels, and calculates the displacement of the two travel pumps 22 based on the speed deviation.

[0115] C40: Adjust the displacement of the two traveling pumps 22 according to the calculation results.

[0116] In this step, the displacement of the two traveling pumps 22 is adjusted according to the calculation results.

[0117] C50: Measure whether the actual speed of the two motor sets 24 is within the calculated speed range. If yes, execute C10; otherwise, execute C60.

[0118] In this step, a speed sensor is installed on the motor assembly 24 to monitor the real-time output speed of the motor assembly 24. Based on whether the actual speed of the motor assembly 24 is within the calculated speed range, it is determined whether the adjustment of the displacement of the walking pump 22 meets the requirements.

[0119] C60: Based on the deviation between the actual speed and the calculated speed of the two motor sets 24, adjust the calculation results of the left and right walking pumps 22, and return to C40.

[0120] In this step, if the actual speed of the two motor groups 24 is not within the calculated speed range, the calculation results are fine-tuned, and C40 is re-executed based on the fine-tuned calculation structure.

[0121] like Figure 9 As shown, to ensure that both the front-wheel drive module 2 and the rear-wheel drive module exert reasonable traction, front and rear wheel load force control is superimposed. Since the mass distribution between the front and rear axles is a:b, the overall vehicle traction is optimal when the front and rear wheel load ratio is a:b, meaning there is no slippage. Therefore, it is necessary to adjust the driving force of the front-wheel drive module 2 and the driving force of the rear-wheel drive module. Optionally, the grader's travel system control strategy also includes a front-to-rear wheel power distribution control strategy, which includes:

[0122] D10: The grader is in all-wheel drive mode.

[0123] D20: Measure the load on the front wheel (a) and the load on the rear wheel (b).

[0124] In this step, the engine load of the rear drive module is measured. The front wheel load 'a' is calculated by measuring the pressure of the motor assembly 24 of the front drive module using sensors. Since the front-drive grader is primarily in driving mode when in all-wheel drive, and the working device is not moving significantly, the working, cooling, and other load values ​​remain essentially constant. Therefore, the data measured at idle speed is used as the working, cooling, and other load values. Thus, the rear wheel load 'b' = engine load - working, cooling, and other loads - front wheel load. Preferably, a / b = 3 / 7.

[0125] D30: Is the ratio of the front wheel load to the rear wheel load equal to a / b±c? If yes, then execute D40; otherwise, execute D50.

[0126] In this step, c represents the allowable error value. If the front wheel load is a / b ± c compared to the rear wheel load, the vehicle is considered to be moving normally, and D40 is executed; otherwise, D50 is executed.

[0127] D40: Maintain current driving status.

[0128] The D50 specifically includes:

[0129] D501: Determine the relationship between the ratio R of the front wheel load to the rear wheel load and a / b±c. If R < a / b±c, then execute D502; if R > a / b±c, then execute D503.

[0130] D502: Adjust the displacement of the travel pump 22 to increase the driving force of the front wheels.

[0131] In this step, if the ratio R of the front wheel load to the rear wheel load is less than a / b±c, then the rear wheel is pushing the front wheel to move. The vehicle may be traveling on relatively muddy ground or uphill. In this case, while ensuring the speed is consistent, the displacement of the travel pump 22 is slightly adjusted to increase the pressure in the front wheel drive module 2 and increase the front wheel drive force.

[0132] D503: Adjust the displacement of the travel pump 22 to reduce the driving force of the front wheels.

[0133] If the ratio R of the front wheel load to the rear wheel load is greater than a / b±c, then the front wheel is dragging the rear wheel and the rear wheel is not exerting actual traction. It is then determined that the vehicle may be traveling on relatively soft ground, such as sand or snow. In this case, while ensuring the speed remains the same, the displacement of the travel pump 22 is slightly adjusted to reduce the pressure in the front wheel drive module 2 and reduce the front wheel drive force.

[0134] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A control strategy for a grader's walking system, applied to the grader's walking system, characterized in that: The grader's walking system includes an oil tank (1), a front wheel drive module (2) and a rear wheel drive module. The front wheel drive module (2) includes an oil replenishment pump (21), two walking pumps (22) that correspond one-to-one with the three, two free wheel valves (23) and two motor sets (24). The grader's walking system control strategy includes a mode switching control strategy, which includes: A10: Grader starts; A20: Determine if a rear wheel independent drive command has been issued. If yes, execute A30; otherwise, execute A40. A30: The free wheel valve (23) is in a free state and controls the rear wheel drive module to work independently. The free state means that the oil inlet and oil outlet of the motor assembly (24) are connected to the oil tank (1) respectively. A40: Determine if the speed of the grader V < vkm / h and it is in neutral. If yes, execute A50; otherwise, execute A30. A50: The freewheel valve (23) switches to the transition state, adjusts the displacement of the travel pump (22) to match the actual vehicle speed, and after t seconds, switches to the drive state. The transition state is that the oil outlet of the oil replenishment pump (21) is simultaneously connected to the oil inlet and oil outlet of the motor assembly (24). The drive state is that the travel pump (22) and the motor assembly (24) are connected to form a closed hydraulic circuit. A60: Determine if a front wheel independent drive command has been issued. If yes, execute A70; otherwise, execute A80. A70: The front-wheel drive module (2) operates independently; A80: The front-wheel drive module (2) and the rear-wheel drive module work together.

2. The control strategy for the grader's walking system according to claim 1, characterized in that, The grader's walking system control strategy also includes a braking control strategy, which includes: B10: Collect the braking signal of the grader; B20: Determine if a brake signal is generated. If yes, execute B40; otherwise, execute B30. B30: The freewheel valve (23) is in the free state, and B60 is executed; B40: Determine if the vehicle is in all-wheel drive mode. If yes, execute B50; otherwise, execute B30. B50: The pressure of the walking pump (22) is reduced to the set pressure of the oil replenishment pump (21) or slightly higher than the set pressure of the oil replenishment pump (21); B60: The service braking module (3) brakes the two rear wheels of the rear wheel drive module and returns to B10.

3. The control strategy for the grader's walking system according to claim 2, characterized in that, The B50 also includes: the rate at which the displacement of the travel pump (22) decreases is consistent with the rate at which the vehicle speed decreases.

4. The control strategy for the grader's walking system according to claim 1, characterized in that, The grader's walking system control strategy also includes a steering control strategy, which includes: C10: Collect the position of the articulated steering cylinder (41) of the articulated steering module (4) and the position of the front wheel steering cylinder (51) of the front wheel steering module (5); C20: Determine whether the position of the articulated steering cylinder (41) and / or the position of the front wheel steering cylinder (51) has changed. If yes, execute C30; otherwise, execute C10. C30: Calculate the speed deviation between the left and right front wheels and the displacement of the two travel pumps (22) on the left and right sides; C40: Adjust the displacement of the two walking pumps (22) according to the calculation results.

5. The control strategy for the grader's walking system according to claim 4, characterized in that, The steering control strategy also includes: C50: Measure whether the actual speed of the two motor sets (24) is within the calculated speed range. If yes, execute C10; otherwise, execute C60. C60: Based on the deviation between the actual speed and the calculated speed of the two motor sets (24), adjust the calculation results of the left and right walking pumps (22) and return to C40.

6. The control strategy for the grader's walking system according to claim 1, characterized in that, The grader's walking system control strategy also includes a front-to-rear wheel power distribution control strategy, which includes: D10: The grader is in all-wheel drive mode; D20: Measure the front wheel load a and the rear wheel load b; D30: Is the ratio of the front wheel load to the rear wheel load equal to a / b±c? If yes, then execute D40; otherwise, execute D50. D40: Maintain current driving status; D50: Adjust the displacement of the walking pump (22) to synchronize the speed of the front and rear wheels.

7. The control strategy for the grader's walking system according to claim 6, characterized in that, The D50 specifically includes: D501: Determine the relationship between the ratio R of the front wheel load to the rear wheel load and a / b±c. If R < a / b±c, then execute D502; if R > a / b±c, then execute D503. D502: Adjust the displacement of the travel pump (22) to increase the driving force of the front wheels. D503: Adjust the displacement of the travel pump (22) to reduce the driving force of the front wheels.

8. A grader walking system, controlled by the grader walking system control strategy according to any one of claims 1-7, characterized in that, include: Fuel tank (1); The front-wheel drive module (2) includes two travel pumps (22), two freewheel valves (23), two motor sets (24), and a fuel replenishment pump (21). The two travel pumps (22), two freewheel valves (23), and two motor sets (24) correspond one-to-one. The fuel replenishment pump (21) has its inlet connected to the fuel tank (1), and the fuel replenishment port of the travel pumps (22) is connected to the fuel tank (1). The displacement of the fuel replenishment pump (21) is less than that of the travel pumps (22). The freewheel valves (23) include a free state, a driven state, and a... In the transition state, in the free state, the oil outlet and oil inlet of the walking pump (22) are connected, and the oil inlet and oil outlet of the motor assembly (24) are respectively connected to the oil tank (1). In the driving state, the oil outlet of the walking pump (22) is connected to the oil inlet of the motor assembly (24), and the oil outlet of the motor assembly (24) is connected to the oil inlet of the walking pump (22). In the transition state, the oil outlet and oil inlet of the walking pump (22) are connected, and the oil inlet and oil outlet of the motor assembly (24) are simultaneously connected to the oil outlet of the replenishing pump (21). The rear-wheel drive module works synchronously with the front-wheel drive module (2) or independently; Service brake module (3), the service brake module (3) is used to brake the two rear wheels of the rear wheel drive module; The articulated steering module (4) and the front wheel steering module (5) are equipped with an articulated steering cylinder (41) of the articulated steering module (4) and a front wheel steering cylinder (51) of the front wheel steering module (5), which can control the steering of the grader.

9. The grader walking system according to claim 8, characterized in that, The motor assembly (24) includes a first valve (241), a first motor (242), and a second motor (243). The first port of the first valve (241) serves as the oil inlet of the motor assembly (24), the second port of the first valve (241) serves as the oil outlet of the motor assembly (24), the third port of the first valve (241) is connected to the oil inlet of the first motor (242), the fourth port of the first valve (241) is connected to the oil inlet of the second motor (243), and the oil outlets of the first motor (242) and the second motor (243) are connected to the fifth port of the first valve (241). The first valve (241) includes a first position a and a second position a. At the first position a of the first valve (241), the first port of the first valve (241) is connected to the third port and the fourth port of the first valve (241) respectively, and the second port is connected to the fifth port. At the second position a of the first valve (241), the first port of the first valve (241) is connected to the third port of the first valve (241), and the second port of the first valve (241) is connected to the fourth port and the fifth port of the first valve (241) respectively.

10. The grader walking system according to claim 9, characterized in that, The first valve (241) includes a first valve body, a first valve core and a first return spring. The first valve core is slidably disposed in the first valve body. The first valve body is provided with a first control oil port. The first control oil port of the first valve body is located on one side of the first valve core. The first return spring is disposed in the first valve body and located on the other side of the first valve core. The front wheel drive module (2) also includes a speed control valve (25). The first interface of the speed control valve (25) is connected to the oil outlet of the oil replenishment pump (21). The second interface of the speed control valve (25) is connected to the oil tank (1). The third interface of the speed control valve (25) is connected to the first control oil port of the first valve (241). The speed control valve (25) includes a first position b and a second position b. At the first position b, the first interface of the speed control valve (25) and the third interface of the speed control valve (25) are connected. At the second position b, the second interface of the speed control valve (25) and the third interface of the speed control valve (25) are connected.

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