Land leveler walking system control strategy and land leveler walking system

Abstract

The invention relates to the technical field of engineering machinery, and particularly discloses a land leveler walking system control strategy and a land leveler walking system.The land leveler walking system is applied to a land leveler walking system.The land leveler walking system comprises an oil tank, a front wheel driving module and a rear wheel driving module; the two walking pumps, the two free wheel valves and the two motor sets are in one-to-one correspondence with the oil supplementing pump, each free wheel valve comprises a free state, a driving state and a transition state, in the free state, oil inlets and oil outlets of the motor sets are communicated with the oil tank, and in the driving state, the oil inlets and the oil outlets of the motor sets are communicated with the oil tank. The walking pump and the motor set are connected to form a closed hydraulic loop, and in the transition state, an oil inlet of the oil supplementing pump is communicated with an oil inlet and an oil outlet of the motor set at the same time. And when the mode switching control strategy is executed and the front wheel driving module intervenes, it is guaranteed that the vehicle is in the neutral gear and the vehicle speed V is smaller than vkm / h. The transition state of the free wheel valve is modulated firstly, oil supplementing pressure is led to the two sides of the hydraulic motor, and impact is reduced. And the stability of the walking system of the land leveler is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of engineering machinery, and in particular to a control strategy for a motor grader traveling system and a motor grader traveling system. Background Art

[0002] A motor grader is an earth-moving machine that uses a scraper to level the ground. The scraper is installed between the front and rear axles of the machine and can be raised and lowered, tilted, rotated and extended. It is flexible and accurate in movement, easy to operate, and can level the ground with high precision. It is suitable for building roadbeds and pavements, building slopes, and digging ditches. It can also mix road mixtures, remove snow, push bulk materials, and maintain dirt and gravel roads.

[0003] The current motor graders are mainly rear-wheel driven, with the front wheels as passive wheels, and some are all-wheel drive motor graders. Motor graders with rear-wheel drive alone are only suitable for single working conditions, and the front wheels are required to provide power in more and more working conditions. Therefore, all-wheel drive motor graders are gradually becoming popular.

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

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

[0006] The purpose of the present invention is to provide a control strategy for a motor grader travel system and a motor grader travel system, so as to solve the problem in the related art that when the motor grader starts the front drive, the pressure in the front wheel hydraulic system changes suddenly, which easily causes hydraulic shock, 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 motor grader travel system, which is applied to a motor grader travel system, wherein the motor grader travel system comprises a fuel tank, a front wheel drive module and a rear wheel drive module, wherein the front wheel drive module comprises a replenishing pump and two travel pumps, two free wheel valves and two motor groups corresponding to each other;

[0008] The control strategy of the motor grader travel system includes a mode switching control strategy, and the mode switching control strategy includes:

[0009] A10: The grader starts;

[0010] A20: Determine whether a rear wheel independent driving command is issued. If yes, execute A30; if no, execute A40;

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

[0012] A40: Determine whether the speed of the grader V is less than vkm / h and the grader is in neutral. If so, execute A50; otherwise, execute A30.

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

[0014] A60: Determine whether the front wheel independent driving command is issued. If yes, execute A70; if no, execute A80;

[0015] A70: the front wheel drive module works alone;

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

[0017] As a preferred technical solution of the control strategy of the grader travel system, the control strategy of the grader travel system also includes a braking control strategy, and the braking control strategy includes:

[0018] B10: collecting the brake signal of the grader;

[0019] B20: Determine whether a brake signal is generated. If yes, execute B40; if no, execute B30;

[0020] B30: the free wheel valve is in the free state, and B60 is executed;

[0021] B40: Determine whether the vehicle is in front and rear all-wheel drive mode. If yes, execute B50; if no, execute B30;

[0022] B50: The travel pump pressure is adjusted down to the set pressure of the charge pump or slightly higher than the set pressure of the charge pump;

[0023] B60: The service brake 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 travel system, the B50 also includes: the travel pump displacement reduction rate is consistent with the vehicle speed reduction rate.

[0025] As a preferred technical solution of the control strategy of the grader walking system, the control strategy of the grader walking system also includes a steering control strategy, and the steering control strategy 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 so, execute C30; if not, execute C10;

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

[0029] C40: According to the calculation results, the displacement of the two travel pumps is adjusted.

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

[0031] C50: Measure whether the actual speeds of the two motor groups are within the calculated speed range. If so, execute C10; if not, execute C60;

[0032] C60: According to the deviation between the actual rotation speed of the two motor groups and the calculated rotation speed, the calculation results of the left and right travel pumps are adjusted, and the process returns to C40.

[0033] As a preferred technical solution of the control strategy of the motor grader walking system, the control strategy of the motor grader walking system also includes a front and rear wheel power distribution control strategy, and the front and rear wheel power distribution control strategy includes:

[0034] D10: the motor grader is in front and rear 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, execute D40; if no, execute D50;

[0037] D40: Maintain the current driving state;

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

[0039] As the preferred technical solution of the control strategy of the grader 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, execute D502; if R>a / b±c, execute D503;

[0041] D502: Adjust the displacement of the travel pump to increase the front wheel driving force:

[0042] D503: Adjust the travel pump displacement to reduce the front wheel driving force.

[0043] On the other hand, the present invention provides a grader travel system, which is controlled by the grader travel system control strategy in any of the above schemes, including:

[0044] tank;

[0045] The front-wheel drive module comprises two travel pumps, two free-wheel valves, two motor groups and an oil replenishment pump, wherein the two travel pumps, the two free-wheel valves and the two motor groups correspond to each other one by one, the oil inlet of the oil replenishment pump is connected to the oil tank, the oil replenishment port of the travel pump is connected to the oil tank, the displacement of the oil replenishment pump is smaller than the displacement of the travel pump, the free-wheel valve comprises a free state, a driving state and a transition state, in the free state, the oil outlet and the oil inlet of the travel pump are connected, the oil inlet and the oil outlet of the motor group are connected to the oil tank respectively, in the driving state, the oil outlet of the travel pump is connected to the oil inlet of the motor group, the oil outlet of the motor group is connected to the oil inlet of the travel pump, in the transition state, the oil outlet and the oil inlet of the travel pump are connected, the oil inlet and the oil outlet of the motor group are simultaneously connected to the oil outlet of the oil replenishment pump;

[0046] A rear-wheel drive module, working synchronously with the front-wheel drive module or working independently;

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

[0048] The articulated steering module and the front wheel steering module, the articulated steering cylinder of the articulated steering module and the front wheel steering cylinder of the front wheel steering module can control the steering of the grader.

[0049] As a preferred technical solution for the grader travel system, the motor group includes a first valve, a first motor and a second motor. The first interface of the first valve serves as the oil inlet of the motor group, and the second interface of the first valve serves as the oil outlet of the motor group. The third interface of the first valve is connected to the oil inlet of the first motor, and the fourth interface of the first valve is connected to the oil inlet of the second motor. The oil outlet of the first motor and the oil outlet of the second motor are connected to the fifth interface of the first valve. The first valve includes a first position a and a second position a. In the first position a of the first valve, the first interface of the first valve is respectively connected to the third interface and the fourth interface of the first valve, and the second interface is connected to the fifth interface. In the second position a of the first valve, the first interface of the first valve is connected to the third interface of the first valve, and the second interface of the first valve is respectively connected to the fourth interface and the fifth interface of the first valve.

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

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

[0052] The beneficial effects of the present invention are:

[0053] The present invention provides a control strategy for a grader travel system and a grader travel system, which are applied to the grader travel system. The grader travel system includes a fuel tank, a front-wheel drive module and a rear-wheel drive module. The front-wheel drive module includes an oil replenishment pump and two travel pumps corresponding to each other, two free-wheel valves and two motor groups. The oil inlet of the oil replenishment pump and the oil replenishment port of the travel pump are respectively connected to the fuel tank. The displacement of the oil replenishment pump is smaller than the displacement of the travel pump. The free-wheel valve includes a free state, a driving state and a transition state. In the free state, the oil inlet and the oil outlet of the motor group are respectively connected to the fuel tank. In the driving state, the travel pump and the motor group are connected to form a closed hydraulic circuit. In the transition state, the oil outlet of the oil replenishment pump is simultaneously connected to the oil inlet and the oil outlet of the motor group. When the free-wheel valve is in the free state, the oil inlet and outlet of the motor group are connected to the oil tank, so that the two front wheels are in a free rotation state. When the free-wheel valve is in the driving state, the travel pump drives the oil to flow in the closed hydraulic circuit composed of the travel pump and the motor group, thereby realizing the motor group driving the corresponding front wheel rotation. When the free-wheel valve is in the transition state, the oil replenishment pump pumps the oil in the oil tank into the oil inlet and outlet of the motor group at the same time, so that the motor group always maintains a certain pressure inside, and can rotate with the movement of the grader.

[0054] When executing the mode switching control strategy, after the motor grader is started, when the rear wheel drive command is recognized, the freewheel valve is adjusted to the free state so that the two front wheels of the front wheel drive module can rotate together with the two rear wheels of the rear wheel drive module to avoid affecting the operation of the rear wheel drive module. When the rear wheel drive command is not recognized, it means that the motor grader will start the front wheel drive mode or the front and rear full drive mode. Both modes require the front wheel drive module to start working. If the vehicle intervenes in the front drive during the driving process, the motor group housing pressure will be higher, exceeding the allowable value, which will have an adverse effect on the life of the motor. Therefore, the program setting does not allow this operation. It must be ensured that the vehicle is in neutral and the speed V<vkm / h. In order to prevent the motor group from switching directly from low pressure to high pressure, the freewheel valve is first modulated to the transition state, and the oil replenishment pressure is led to both sides of the hydraulic motor to reduce the impact. At the same time, the displacement of the travel pump is adjusted to match the actual vehicle speed. After t seconds, it is switched to the driving state, so that the motor group is pre-filled with the oil replenishment pressure. When the motor group oil inlet is connected to the high-pressure oil, the impact on the motor group caused by the direct high pressure is avoided. The stability of the grader's travel system is improved, and the driver's experience is improved. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0057] Figure 3 It is a fluid circuit diagram of a free wheel valve in a fluid circuit of a motor grader travel system in an embodiment of the present invention in a free state;

[0058] Figure 4 It is a fluid circuit diagram of a free wheel valve in a fluid circuit of a motor grader travel system in an embodiment of the present invention in a driving state;

[0059] Figure 5 It is a fluid circuit diagram of a free wheel valve in a fluid circuit of a motor grader travel system in an embodiment of the present invention in a transition state;

[0060] Figure 6 It is a flow chart of the mode switching control strategy of the motor grader walking system control strategy in an embodiment of the present invention;

[0061] Figure 7 It is a flow chart of the braking control strategy of the motor grader walking system control strategy in an embodiment of the present invention;

[0062] Figure 8 A flow chart of the steering control strategy of the motor grader travel system control strategy in an embodiment of the present invention;

[0063] Fig. 9 The flowchart of the front and rear wheel power distribution control strategy of the motor grader walking system control strategy in the embodiment of the present invention is shown.

[0064] In the figure:

[0065] 1. Fuel tank;

[0066] 2. Front wheel drive module; 21. Oil charge pump; 22. Travel pump; 23. Free wheel valve; 231. Second valve; 232. Third valve; 24. Motor group; 241. First valve; 242. First motor; 243. Second motor; 25. Speed ​​regulating 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 DESCRIPTION

[0068] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0069] In the description of the present invention, it should be noted that the orientations or positional relationships indicated by the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. Among them, the terms "first position" and "second position" are two different positions, and the first feature "above", "above" and "above" the second feature include the first feature being directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. The first feature "below", "below" and "below" the second feature include the first feature being directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0070] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0071] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0072] like Figure 1 to Figure 5As shown, the present embodiment provides a travel system for a grader, including a fuel tank 1, a front wheel drive module 2 and a rear wheel drive module. The front wheel drive module 2 includes two travel pumps 22, two free wheel valves 23, two motor groups 24 and an oil replenishment pump 21. The two travel pumps 22, the two free wheel valves 23 and the two motor groups 24 correspond to each other one by one. The oil inlet and the oil outlet of the motor group 24 are simultaneously connected to the oil outlet of the oil replenishment pump 21. The oil inlet of the oil replenishment pump 21 is connected to the fuel tank 1. The oil replenishment port of the travel pump 22 is connected to the fuel tank 1. The displacement is smaller than that of the travel pump 22, and the free-wheel valve 23 includes a free state, a driving state and a transition state. In the free state, the oil outlet and the oil inlet of the travel pump 22 are connected, and the oil inlet and the oil outlet of the motor group 24 are connected to the oil tank 1 respectively. In the driving state, the oil outlet of the travel pump 22 is connected to the oil inlet of the motor group 24, and the oil outlet of the motor group 24 is connected to the oil inlet of the travel pump 22. In the transition state, the oil outlet and the 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 free-wheel valve 23 is in the free state, the oil inlet and the oil outlet of the motor group 24 are both connected to the oil tank 1, so that the two front wheels are in a free rotation state at this time. When the free-wheel valve 23 is in the driving state, the travel pump 22 drives the oil to flow in the closed hydraulic circuit composed of the travel pump 22 and the motor group 24, thereby realizing the motor group 24 driving the corresponding front wheels to rotate. When the free-wheel valve 23 is in the transition state, the oil replenishment pump 21 pumps the oil in the oil tank 1 into the oil inlet and the oil outlet of the motor group 24 at the same time, so that the motor group 24 always maintains a certain pressure inside, and can rotate with the movement of the grader.

[0074] Optionally, the motor group 24 includes a first valve 241, a first motor 242 and a second motor 243, the first interface of the first valve 241 serves as the oil inlet of the motor group 24, the second interface of the first valve 241 serves as the oil outlet of the motor group 24, the third interface of the first valve 241 is connected to the oil inlet of the first motor 242, the fourth interface of the first valve 241 is connected to the oil inlet of the second motor 243, the oil outlet of the first motor 242 and the oil outlet of the second motor 243 are connected to the fifth interface of the first valve 241, the first valve 241 includes a first position a and a second position a, in the first position a of the first valve 241, the first interface of the first valve 241 is respectively connected to the third interface and the fourth interface of the first valve 241, and the second interface is connected to the fifth interface, in the second position a of the first valve 241, the first interface of the first valve 241 is connected to the third interface of the first valve 241, and the second interface of the first valve 241 is respectively connected to the fourth interface and the fifth interface of the first valve 241. In this embodiment, in the first position a of the first valve 241, the oil at the oil inlet of the motor group 24 passes through the first interface of the first valve 241, and then enters the first motor 242 and the second motor 243 from the third interface and the fourth interface of the first valve 241, respectively. At the same time, the oil flowing out of the first motor 242 and the second motor 243 flows to the oil outlet of the motor group 24 through the fifth interface and the second interface of the first valve 241. In the second position a of the first valve 241, the oil at the oil inlet of the motor group 24 passes through the first interface of the first valve 241, and then enters the first motor 242 from the third interface of the first valve 241. At the same time, the oil flowing out of the first motor 242 flows to the oil outlet of the motor group 24 through the fifth interface and the second interface of the first valve 241. 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 at this time.

[0075] As for how the first valve 241 is controlled, optionally, the first valve 241 includes a first valve housing, a first valve core and a first return spring, the first valve core is slidably disposed in the first valve housing, the first valve housing is provided with a first control oil port, the first control oil port of the first valve housing is located on one side of the first valve core, and the first return spring is disposed in the first valve housing and is located on the other side of the first valve core. In this embodiment, when high-pressure oil is introduced into the first control oil 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 in the first control oil port of the first valve housing is removed, the first valve core switches from the second position a to the first position a under the elastic force of the first return spring.

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

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

[0078] As for the specific structure of the free-wheel valve 23, optionally, the free-wheel valve 23 includes 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 in 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 group 24, the fourth oil port of the second valve housing is connected to the oil outlet of the motor group 24, 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 in the second valve housing, so that the second valve core includes a first position c and a second position c, and the free state and the transition state are both connected. The first position c of the second valve core corresponds to the driving state, and the second position c of the second valve core corresponds to the driving state. In the free state, the second valve core is located at the first position c of the second valve core, the first interface and the second interface of the second valve housing are connected, the third interface, the fourth interface and the fifth interface are connected to each other, and 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 interface and the third interface of the second valve housing are connected, and the second interface and the fourth interface are connected. In the transition state, the second valve core is located at the first position c of the second valve core, the first interface and the second interface of the second valve housing are connected, the third interface, the fourth interface and the fifth interface are connected to each other, and the fifth interface is connected to the oil replenishment pump 21.

[0079] The second valve 231 also includes a second return spring, and the second valve housing also includes a first control oil port and a second control oil port. The first control oil 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 oil 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 in the third valve housing. The first interface of the third valve housing is communicated with the oil outlet of the replenishing pump 21, the second interface of the third valve housing is communicated with the oil tank 1, the third interface of the third valve housing is communicated with the first control oil port of the second valve housing, and the fourth interface of the third valve housing is communicated with the fifth interface of the second valve housing and the second control oil 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 located at the first position d of the third valve core, the first interface of the third valve housing is communicated with the fourth interface of the third valve housing, and the second interface of the third valve housing is communicated with the third interface of the third valve housing; when the third valve core is located at the second position d of the third valve core, the first interface of the third valve housing is blocked, and the second interface of the third valve housing is respectively communicated with the third interface and the fourth interface of the third valve housing; when the third valve core is located at the third position d of the third valve core, the second interface of the third valve housing is blocked, and the first interface of the third valve housing is respectively communicated with the third interface and the fourth interface of the third valve housing.

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

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

[0083] Optionally, the motor grader travel system further includes a service brake module 3, and the service brake module 3 is used to brake the two rear wheels of the rear wheel drive module.

[0084] Optionally, the motor grader travel system further includes an articulated steering module 4 and a front wheel steering module 5 , and 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 steering of the motor grader.

[0085] like Figure 6 As shown, the control strategy of the grader travel system includes a mode switching control strategy, and the mode switching control strategy includes:

[0086] A10: The grader starts;

[0087] A20: Determine whether a rear wheel independent driving command is issued. If yes, execute A30; if no, execute A40;

[0088] In this step, the staff can issue a rear wheel independent drive command by operating the control panel of the grader.

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

[0090] In this step, when the rear wheel independent drive instruction is identified, the free wheel valve 23 is adjusted to a 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 to avoid affecting the operation of the rear wheel drive module.

[0091] A40: Determine whether the grader speed V is less than vkm / h and is in neutral. If so, execute A50; otherwise, execute A30.

[0092] In this step, if the vehicle intervenes in the front drive during the driving process, the housing pressure of the motor group 24 will be higher, exceeding the allowable value, which will have an adverse effect on the life of the motor. Therefore, the program setting does not allow such operation. It must be ensured that the vehicle is in neutral and the speed V is less than vkm / h. Specifically, the value of v is 0.5km / h-1km / h, and preferably, the value of v is 0.5km / h.

[0093] A50: The free-wheel valve 23 switches to the transition state, and adjusts the displacement of the travel pump 22 to match the actual vehicle speed. After t seconds, it switches to the driving state;

[0094] In this step, in order to prevent the motor group 24 from directly switching from low pressure to high pressure, the free wheel valve 23 is first adjusted to the transition state, and the oil replenishment pressure is introduced to both sides of the hydraulic motor to reduce the impact. At the same time, the displacement of the travel pump 22 is adjusted to match the actual vehicle speed. After t seconds, it is switched to the driving state, so that the motor group 24 is pre-filled with the oil replenishment pressure. When the oil inlet of the motor group 24 passes through the high-pressure oil, the impact on the motor group 24 caused by the direct high pressure passing through the motor group 24 is avoided. The stability of the grader travel system is improved, and the driver's experience is improved.

[0095] A60: Determine whether the front wheel independent driving command is issued. If yes, execute A70; if no, execute A80;

[0096] A70: Front-wheel drive module 2 works alone;

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

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

[0099] B10: Collect the brake signal of the grader;

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

[0101] B20: Determine whether a brake signal is generated. If yes, execute B40; if no, execute B30;

[0102] In this step, since the front wheel can only rely on the hydraulic circuit to brake or the front wheel quits driving, and the rear wheel has brakes, that is, when the brake pedal is pressed, only the rear wheel is braked. If the front wheel drive module 2 quits driving, the free wheel valve 23 needs to be adjusted to the free state, otherwise the front and rear wheel braking speeds will be inconsistent. In this case, if the brake is applied, after the brake pedal is lifted, the front wheel drive module 2 returns to the driving state. At this time, the front wheel drive module 2 constantly switches between the free state and the driving state, which is not good for the driving experience and the life of the hydraulic motor. Therefore, it is necessary to determine whether the brake signal has a braking situation.

[0103] B30: Free-wheel valve 23 is in free state, execute B60.

[0104] In this step, if there is a braking situation, the free wheel valve 23 needs to be switched to a free state, and the front wheel rotates with the rotation of the rear wheel.

[0105] B40: Determine whether the vehicle is in front and rear all-wheel drive mode. If yes, execute B50; if no, execute B30;

[0106] B50: The pressure of the travel pump 22 is adjusted down to the set pressure of the charge pump 21 or slightly higher than the set pressure of the charge pump 21. The displacement reduction rate of the travel pump 22 is consistent with the speed reduction rate of the vehicle.

[0107] In this step, the pressure of the travel pump 22 is adjusted down to the set pressure of the oil replenishment pump 21 or slightly higher than the set pressure of the oil replenishment pump 21, so that the motor group 24 is always at a lower pressure. To ensure the same braking speed of the front and rear wheels and avoid the sudden decrease in the speed of the motor group 24 to cause reverse drag and air suction, the displacement reduction rate of the travel pump 22 is consistent with the speed reduction rate of the vehicle. If the brake pedal is released, the free wheel valve 23 is in the driving state, and the full drive mode can be continued, which protects the motor and avoids the impact on the front wheel drive module 2 during the braking process.

[0108] B60: The service brake module 3 brakes the two rear wheels of the rear-wheel drive module and returns to B10.

[0109] like Figure 8 As shown, optionally, there is a steering angle deviation between the left front wheel and the right front wheel. If this deviation is not corrected, the front wheels on the left and right sides will be worn. If this problem is not solved, the control strategy of the grader walking system also includes a steering control strategy, which includes:

[0110] C10: collecting the position of the articulated steering cylinder 41 and the position of the 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 so, execute C30; if not, execute C10;

[0112] This step is used to determine whether the grader is turning. Specifically, displacement sensors are installed on the articulated steering cylinder 41 and the front wheel steering cylinder 51, and the grader steering angle signal is calculated by the displacement sensor and transmitted to the vehicle controller.

[0113] C30: Calculate the speed deviation of the left and right front wheels and the displacement of the 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 according to the speed deviation.

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

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

[0117] C50: Measure whether the actual rotation speeds of the two motor groups 24 are within the calculated rotation speed range. If so, execute C10; if not, execute C60;

[0118] In this step, a speed sensor for monitoring the real-time output speed of the motor group 24 is provided on the motor group 24. According to whether the actual speed of the motor group 24 is within the calculated speed range, it is judged whether the adjustment of the displacement of the travel pump 22 meets the requirements.

[0119] C60: According to the deviation between the actual rotation speed of the two motor groups 24 and the calculated rotation speed, the calculation results of the left and right travel pumps 22 are adjusted, and the process returns to C40.

[0120] In this step, if the measured actual rotation speeds of the two motor groups 24 are not within the calculated rotation speed range, the calculation result is fine-tuned, and C40 is re-executed according to the fine-tuned calculation structure.

[0121] like Fig. 9 As shown, in order to make both the front-wheel drive module 2 and the rear-wheel drive module exert reasonable traction, the front and rear wheel load force control is superimposed. Since the mass distribution of the front axle and the rear axle is a:b, the traction of the whole vehicle is best when the load ratio of the front wheel and the rear wheel is a:b, that is, there is no slipping. For this reason, 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 control strategy of the grader walking system also includes the front and rear wheel power distribution control strategy, and the front and rear wheel power distribution control strategy includes:

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

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

[0124] In this step, the engine load of the rear drive module is measured. The front wheel load a is calculated by the pressure of the motor group 24 of the front drive module measured by the sensor. Since the front-drive grader is mainly in driving condition when it is fully driven, and the working device basically does not move when it is working, the working, heat dissipation and other load values ​​are basically unchanged, and the data measured at idle speed is taken as the working, heat dissipation and other load values. Then the rear wheel load b = engine load - working, heat dissipation 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, execute D40; if no, execute D50;

[0126] In this step, c is the allowable error value. If the front wheel load is a / b±c, the vehicle is judged to be running normally, and D40 is executed, otherwise D50 is executed.

[0127] D40: Maintain current driving status.

[0128] 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, execute D502; if R>a / b±c, execute D503;

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

[0131] In this step, if the ratio R of the front wheel load to the rear wheel load is less than a / b±c, the rear wheels push the front wheels and the vehicle may be traveling on muddy ground or uphill. To ensure a consistent speed, the displacement of the travel pump 22 is fine-tuned to increase the pressure in the front wheel drive module 2 and improve the front wheel driving force.

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

[0133] If the ratio R of the front wheel load to the rear wheel load is greater than a / b±c, it means that the front wheel is dragging the rear wheel and the rear wheel is not exerting actual traction. It is judged that the whole vehicle may be traveling on relatively soft ground, such as sand or snow. In this case, the displacement of the travel pump 22 is fine-tuned while ensuring the speed is consistent, so as to reduce the pressure in the front wheel drive module 2 and reduce the front wheel driving 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 embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. The control strategy of the motor grader travel system is applied to the motor grader travel system, which is characterized by: The motor grader travel system comprises a fuel tank (1), a front wheel drive module (2) and a rear wheel drive module, wherein the front wheel drive module (2) comprises an oil replenishment pump (21), two travel pumps (22) corresponding to each other, two free wheel valves (23) and two motor groups (24); The control strategy of the motor grader travel system includes a mode switching control strategy, and the mode switching control strategy includes: A10: The grader starts; A20: Determine whether a rear wheel independent driving command is issued. If yes, execute A30; if no, execute A40; A30: The free-wheel valve (23) is in a free state and controls the rear-wheel drive module to work alone. The free state means that the oil inlet and the oil outlet of the motor group (24) are respectively connected to the oil tank (1); A40: Determine whether the speed of the grader V is less than vkm / h and the grader is in neutral. If so, execute A50; otherwise, execute A30. A50: The free-wheel valve (23) switches to a transition state, adjusts the displacement of the travel pump (22) to match the actual vehicle speed, and switches to a drive state after t seconds. The transition state is that the oil outlet of the oil replenishment pump (21) is simultaneously connected to the oil inlet and the oil outlet of the motor group (24), and the drive state is that the travel pump (22) and the motor group (24) are connected to form a closed hydraulic circuit; A60: Determine whether the front wheel independent driving command is issued. If yes, execute A70; if no, execute A80; A70: the front wheel drive module (2) works alone; A80: The front-wheel drive module (2) and the rear-wheel drive module work in coordination.

2. The control strategy of the motor grader travel system according to claim 1, characterized in that: The control strategy of the grader travel system also includes a braking control strategy, which includes: B10: collecting the brake signal of the grader; B20: Determine whether a brake signal is generated. If yes, execute B40; if no, execute B30; B30: the free wheel valve (23) is in the free state, and B60 is executed; B40: Determine whether the vehicle is in front and rear all-wheel drive mode. If yes, execute B50; if no, execute B30; B50: the pressure of the travel pump (22) is adjusted down to the set pressure of the oil replenishment pump (21) or slightly greater than the set pressure of the oil replenishment pump (21); B60: The service brake module (3) brakes the two rear wheels of the rear wheel drive module, and returns to B10.

3. The control strategy of the motor grader travel system according to claim 2, characterized in that: The B50 also includes: the displacement reduction rate of the travel pump (22) is consistent with the speed reduction rate of the entire vehicle.

4. The control strategy of the motor grader travel system according to claim 1, characterized in that: The control strategy of the grader walking system also includes a steering control strategy, and the steering control strategy includes: C10: collecting 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 so, execute C30; if not, execute C10; C30: Calculating the speed deviation of the left and right front wheels and the displacement of the left and right travel pumps (22); C40: According to the calculation result, the displacement of the two travel pumps (22) is adjusted.

5. The control strategy of the motor grader travel system according to claim 4, characterized in that: The steering control strategy also includes: C50: Measure whether the actual rotation speeds of the two motor groups (24) are within the calculated rotation speed range. If so, execute C10; if not, execute C60; C60: According to the deviation between the actual rotation speed of the two motor groups (24) and the calculated rotation speed, the calculation results of the left and right travel pumps (22) are adjusted, and the process returns to C40.

6. The control strategy of the motor grader travel system according to claim 1, characterized in that: The control strategy of the motor grader travel system also includes a front and rear wheel power distribution control strategy, and the front and rear wheel power distribution control strategy includes: D10: the motor grader is in front and rear 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, execute D40; if no, execute D50; D40: Maintain the current driving state; D50: adjusting the displacement of the travel pump (22) so as to synchronize the rotation speeds of the front and rear wheels.

7. The control strategy of the motor grader travel 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, execute D502; if R>a / b±c, execute D503; D502: Adjust the displacement of the travel pump (22) to increase the front wheel driving force: D503: Adjust the displacement of the travel pump (22) to reduce the front wheel driving force.

8. A motor grader travel system, controlled by the motor grader travel system control strategy according to any one of claims 1 to 7, characterized in that: include: Fuel tank (1); A front-wheel drive module (2) comprises two travel pumps (22), two free-wheel valves (23), two motor groups (24) and an oil replenishment pump (21), wherein the two travel pumps (22), the two free-wheel valves (23) and the two motor groups (24) correspond to each other in a one-to-one manner, an oil inlet of the oil replenishment pump (21) is connected to the oil tank (1), an oil replenishment port of the travel pump (22) is connected to the oil tank (1), a displacement of the oil replenishment pump (21) is smaller than a displacement of the travel pump (22), and the free-wheel valve (23) comprises a free state, a driving state and a In the transition state, in the free state, the oil outlet and the oil inlet of the travel pump (22) are connected, and the oil inlet and the oil outlet of the motor group (24) are respectively connected to the oil tank (1); in the driving state, the oil outlet of the travel pump (22) is connected to the oil inlet of the motor group (24), and the oil outlet of the motor group (24) is connected to the oil inlet of the travel pump (22); in the transition state, the oil outlet and the oil inlet of the travel pump (22) are connected, and the oil inlet and the oil outlet of the motor group (24) are simultaneously connected to the oil outlet of the replenishing pump (21); A rear-wheel drive module, working synchronously with the front-wheel drive module (2) or working independently; A service brake module (3), the service brake module (3) being used to brake the two rear wheels of the rear wheel drive module; 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 steering of the grader.

9. The motor grader travel system according to claim 8, characterized in that: The motor group (24) comprises a first valve (241), a first motor (242) and a second motor (243); the first interface of the first valve (241) serves as an oil inlet of the motor group (24); the second interface of the first valve (241) serves as an oil outlet of the motor group (24); the third interface of the first valve (241) is in communication with the oil inlet of the first motor (242); the fourth interface of the first valve (241) is in communication with the oil inlet of the second motor (243); the oil outlet of the first motor (242) and the oil outlet of the second motor (243) are in communication with the fifth interface of the first valve (241); The first valve (241) includes a first position a and a second position a. In the first position a of the first valve (241), the first interface of the first valve (241) is respectively connected to the third interface and the fourth interface of the first valve (241), and the second interface is connected to the fifth interface. In the second position a of the first valve (241), the first interface of the first valve (241) is connected to the third interface of the first valve (241), and the second interface of the first valve (241) is respectively connected to the fourth interface and the fifth interface of the first valve (241).

10. The motor grader travel system according to claim 9, characterized in that: The first valve (241) comprises a first valve housing, a first valve core and a first return spring, the first valve core is slidably disposed in the first valve housing, the first valve housing is provided with a first control oil port, the first control oil port of the first valve housing is located on one side of the first valve core, and the first return spring is disposed in the first valve housing and on the other side of the first valve core; The front-wheel drive module (2) further comprises a speed regulating valve (25), wherein a first interface of the speed regulating valve (25) is communicated with an oil outlet of the oil replenishing pump (21), a second interface of the speed regulating valve (25) is communicated with the oil tank (1), a third interface of the speed regulating valve (25) is communicated with the first control oil port of the first valve (241), and the speed regulating valve (25) comprises a first position b and a second position b, wherein at the first position b, the first interface of the speed regulating valve (25) is communicated with the third interface of the speed regulating valve (25), and at the second position b, the second interface of the speed regulating valve (25) is communicated with the third interface of the speed regulating valve (25).

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