Steering brake hydraulic system

Abstract

The utility model provides a steering brake hydraulic system which comprises an automatic auxiliary steering system which comprises a first module and a second module, and the first module is connected with the second module. The first module comprises a first pump assembly, a one-way valve set and a brake unit. The first pump assembly is connected with the brake unit through the one-way valve set. The second module comprises a first control valve, an electromagnetic valve set and an angle sensor, the angle sensor is connected with the first control valve, the first pump assembly is connected with the first control valve through a one-way valve set, and the first control valve is connected with the braking unit through the electromagnetic valve set and used for achieving braking. According to the steering and braking hydraulic system, an operator can be assisted to make a turn with a small radius through the first module and the second module of the automatic auxiliary steering system, the driver can cope with various working conditions in field operation without having high driving experience and rich driving skills, and the operation safety is guaranteed.

Description

Technical Field

[0001] The present application relates to the technical field of tractor manufacturing, and in particular to a steering brake hydraulic system. Background Art

[0002] Tractor steering is divided into three structures according to the form of the whole machine platform structure: front-wheel steering, articulated steering and all-wheel steering. Among them, front-wheel steering is mostly used in frameless tractors (the front and rear wheels are of different sizes), articulated steering is mostly used in high-horsepower articulated tractors (the front and rear wheels are of the same size), and all-wheel steering is used for tractors of individual manufacturers (the front and rear wheels are of the same size) with integral frames.

[0003] When the tractor is in the field, the turning radius in some working conditions is small, and the conventional steering mentioned above cannot achieve a small-radius turn. Especially for large tractors, due to the large size of the entire machine, the conventional steering mentioned above cannot achieve a small-radius turn.

[0004] In response to this situation, some braking methods involve human intervention during the steering process, using the operator's foot to step on the brake pedal to achieve unilateral auxiliary braking, and then during the normal turning process, due to unilateral auxiliary braking on one side, the tire on the auxiliary braking side is at a lower speed or even stops rotating, while the tire on the other side speeds up due to the bridge differential effect (the bridge differential effect allows the two wheels to rotate at different speeds to meet the different driving distances of the wheels on both sides when the vehicle turns. When turning, the outer wheel needs to travel a longer distance and the inner wheel needs to travel a shorter distance, thereby achieving the purpose of meeting the different driving distances of the wheels) to achieve a small radius turn, or even a small radius turn in which one side of the vehicle is stationary while the other side tire turns around the stationary tire. For the existing braking methods, the operator needs a high level of driving skills and rich driving experience to cope with a variety of working conditions in field operations, and improper operation may also cause the risk of rollover.

[0005] Therefore, it is necessary to design a steering brake hydraulic system to solve the above problems. Utility Model Content

[0006] In view of this, in order to overcome the defects of the prior art, the utility model provides a steering brake hydraulic system, which effectively solves the problem that the existing braking method requires manual operation, tests the operator's driving level and easily creates safety risks.

[0007] According to a steering brake hydraulic system provided by the utility model, the steering brake hydraulic system includes an automatic auxiliary steering system, the automatic auxiliary steering system includes a first module and a second module, the first module is connected to the second module; the first module includes a first pump component by outputting pressure, a one-way valve group for controlling flow direction and a brake unit for braking the tractor, the first pump component is connected to the brake unit through the one-way valve group, and the first pump component can drive the brake unit to achieve braking through the one-way valve group; the second module includes a first control valve, a solenoid valve group and an angle sensor, the angle sensor is arranged on the tractor for detecting the steering angle of the tractor, the angle sensor is connected to the first control valve, the first pump component is connected to the first control valve through the one-way valve group, the first control valve is connected to the brake unit through the solenoid valve group, and the angle feedback by the angle sensor causes the first control valve to output different pressures for controlling the brake unit to achieve corresponding braking.

[0008] Preferably, the second module also includes a second control valve and a first pressure sensor group, the first pressure sensor group is arranged in the braking unit for detecting the pressure value, the second control valve is arranged between the one-way valve group and the braking unit, the second control valve is connected to the first pressure sensor group and the braking unit, and the value fed back by the first pressure sensor group is used to enable the second control valve to adjust the output pressure to adjust the auxiliary braking pressure.

[0009] Preferably, the first control valve is a proportional pressure reducing valve, and the second control valve is a proportional solenoid valve.

[0010] Preferably, the steering brake hydraulic system also includes a conventional steering system and a controller, wherein the controller can enable the tractor to switch between the conventional steering system and the automatic assisted steering system, and the conventional steering system and the automatic assisted steering system are arranged in parallel; the conventional steering system includes a second pump assembly for outputting pressure, a steering control unit for controlling the output pressure, and a steering execution unit for steering the tractor, and the second pump assembly is connected to the steering execution unit through the steering control unit.

[0011] Preferably, the one-way valve group includes a first one-way valve, a second one-way valve and a third one-way valve, the second one-way valve and the third one-way valve are connected in parallel, the second one-way valve and the third one-way valve are both connected in series with the first one-way valve, and the first one-way valve is connected to the first pump assembly; the steering control unit includes a priority valve; the steering execution unit includes a steering gear, a first steering cylinder and a second steering cylinder; the second pump assembly is connected to the steering gear through the priority valve, the first steering cylinder and the second steering cylinder are connected in parallel, and the first steering cylinder and the second steering cylinder are both connected in series with the steering gear; the steering control unit also includes a shuttle valve group, which is arranged before the priority valve and the steering gear, and the shuttle valve group includes a first input port connected to the second pump assembly for receiving a load pressure, a second input port that can be connected to a working hydraulic system so as to receive a feedback pressure from the working hydraulic system, and an output port for transmitting the larger pressure at the first input port and the second input port to the second pump assembly to control the operation of the second pump assembly.

[0012] Preferably, the brake unit includes a first brake valve, a second brake valve, a first front and rear brake and a second front and rear brake, the first front and rear brake is connected to the second one-way valve through the first brake valve, and the second front and rear brake is connected to the third one-way valve through the second brake valve.

[0013] Preferably, the first control valve is connected in parallel with the second one-way valve and the third one-way valve, the solenoid valve group includes a first solenoid valve and a second solenoid valve, the first control valve is connected to the first front and rear brakes through the first solenoid valve, and the first control valve is connected to the second front and rear brakes through the second solenoid valve; the first pressure sensor group includes a first pressure sensor and a second pressure sensor, the first pressure sensor is connected to the first solenoid valve, and the second pressure sensor is connected to the second solenoid valve.

[0014] Preferably, the first pressure sensor and the second pressure sensor are one of a strain gauge pressure sensor, a piezoresistive pressure sensor, a capacitive pressure sensor and a piezoelectric pressure sensor.

[0015] Preferably, the one-way valve group also includes an accumulator group, a second pressure sensor group, a second overflow valve and a unloading valve. The first pump assembly is connected to the second overflow valve and the unloading valve. The second overflow valve and the unloading valve are connected to the accumulator group so that the accumulator group starts to fill or stops filling. The second pressure sensor group is connected to the accumulator group to feedback the condition of the accumulator at this time.

[0016] Preferably, the accumulator group includes a first accumulator and a second accumulator, the second pressure sensor group includes a third pressure sensor and a fourth pressure sensor, the first accumulator is connected to the third pressure sensor, the first brake valve and the first front and rear brakes, and the second accumulator is connected to the fourth pressure sensor, the second brake valve and the second front and rear brakes.

[0017] According to the steering brake hydraulic system of the utility model, the first module and the second module of the automatic assisted steering system can assist the operator to make turns with a small radius. The driver does not need to have high driving experience and rich driving skills, and can cope with various working conditions in field operations to ensure operation safety.

[0018] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 A schematic structural diagram of a steering brake hydraulic system according to an embodiment of the utility model is shown;

[0021] Figure 2 A schematic structural diagram of a conventional steering system according to an embodiment of the utility model is shown;

[0022] Figure 3 A schematic structural diagram of an automatic assisted steering system according to an embodiment of the utility model is shown.

[0023] Figure markings: 1-second pump assembly; 2-first overflow valve; 3-priority valve; 4-shuttle valve group; 5-steering gear; 6-first steering cylinder; 7-second steering cylinder; 8-first one-way valve; 9-second one-way valve; 10-first accumulator; 11-third pressure sensor; 12-first brake valve; 13-first pressure sensor; 14-fourth one-way valve; 15-first front brake; 16-first rear brake; 17-second rear brake; 18-second front brake; 19-second pressure sensor; 20-fifth one-way valve; 21-second solenoid valve; 22-first solenoid valve; 23-second brake valve; 24-second control valve; 25-fourth pressure sensor; 26-third one-way valve; 27-first control valve; 28-second accumulator; 29-unloading valve; 30-second overflow valve; 31-first pump assembly; 32-oil tank. DETAILED DESCRIPTION

[0024] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. The components of the embodiments of the present application generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application.

[0025] In the description of the embodiments of the present application, it should be noted that the terms "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, or the positions or positional relationships in which the product of the application is usually placed when in use. They are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply 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 a limitation on the present application. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0026] In addition, the terms "horizontal", "vertical" and the like do not mean that the components are required to be absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0027] In the description of the embodiments of the present application, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "setting", "installation", "connection", and "connection" 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 connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0028] According to a steering brake hydraulic system provided by the utility model, Figures 1 to 3 As shown, the steering brake hydraulic system is used for a tractor and can assist the tractor in performing small-angle braking and steering. The steering brake hydraulic system includes an automatic assisted steering system, which includes a first module and a second module.

[0029] In the following description, reference will be made to Figures 1 to 3 The detailed structure of the automatic assisted steering system of the steering brake hydraulic system including the first module and the second module is specifically described.

[0030] like Figure 1 and Figure 3 As shown, in an embodiment, the automatic assisted steering system includes a first module and a second module, the first module is connected to the second module, the first module is a brake hydraulic module, and the second module is an auxiliary brake rotation module; the first module can output the pressure required for braking, and the second module can realize assisted braking steering.

[0031] Specifically, the first module includes a first pump assembly 31 for outputting pressure, a one-way valve group for controlling flow direction, and a brake unit for braking the tractor. The first pump assembly 31 is connected to the brake unit through the one-way valve group. The first pump assembly 31 can drive the brake unit to achieve braking through the one-way valve group. The first pump assembly 31 can be an automatic pump.

[0032] The auxiliary brake rotation system includes a first control valve 27, a solenoid valve group and an angle sensor (not shown). The angle sensor is arranged on the tractor to detect the steering angle of the tractor. The angle sensor can be arranged on the articulated pin shaft to feed back the angle value by detecting the rotation angle between the articulated frame and the front frame, or a magnetic telescopic sensor built into or external to the steering cylinder can be used to detect the extension length of the piston rod. In addition, the following controller (not shown) can calculate the steering angle of the entire tractor according to the detected angle value or extension length and the parameters of the overall steering structure of the tractor. It should be noted here that the angle sensor, steering cylinder, magnetic telescopic sensor and controller are all components in the prior art, and their structures, installation methods, detection methods and calculation methods are all known to those skilled in the art and will not be repeated here.

[0033] The angle sensor is connected to the first control valve 27, the first pump assembly 31 is connected to the first control valve 27 through a one-way valve group, the first control valve 27 is connected to the brake unit through a solenoid valve group, and the angle fed back by the angle sensor is used to make the first control valve 27 output different pressures to control the brake unit to achieve corresponding braking.

[0034] The first pump assembly 31 is capable of drawing hydraulic fluid from the oil tank 32 and delivering the hydraulic fluid to a brake unit or a control unit of the tractor to brake or steer the tractor.

[0035] Preferably, if Figure 1 and Figure 3 As shown, in the embodiment, the auxiliary brake rotation system also includes a second control valve 24 and a first pressure sensor group. The first pressure sensor group is arranged in the brake unit for detecting the pressure value. The second control valve 24 is arranged between the one-way valve group and the brake unit. The second control valve 24 is connected to the first pressure sensor group and the brake unit. The value fed back by the first pressure sensor group is used to enable the second control valve 24 to adjust the output pressure to adjust the auxiliary braking pressure.

[0036] Preferably, the first control valve 27 is a proportional pressure reducing valve, and the second control valve 24 is a proportional solenoid valve.

[0037] Preferably, if Figure 1 and Figure 3 As shown, in an embodiment, the one-way valve group may include a first one-way valve 8, a second one-way valve 9 and a third one-way valve 26, the second one-way valve 9 and the third one-way valve 26 are connected in parallel, the second one-way valve 9 and the third one-way valve 26 are both connected in series with the first one-way valve 8, and the first one-way valve 8 is connected to the first pump assembly 31; the first one-way valve 8 is arranged in the main pipeline, the second one-way valve 9 and the third one-way valve 26 are arranged in the branch pipeline, and respectively control the front and rear wheels on the left side and the front and rear wheels on the right side of the tractor.

[0038] The brake unit may include a first brake valve 12, a second brake valve 23, a first front and rear brake, and a second front and rear brake. The first front and rear brake may include a first front brake 15 and a first rear brake 16, and the second front and rear brake may include a second front brake 18 and a second rear brake 17. The first front brake 15 and the first rear brake 16 are connected to the second check valve 9 through the first brake valve 12, and the second front brake 18 and the second rear brake 17 are connected to the third check valve 26 through the second brake valve 23. The first brake valve 12 and the second brake valve 23 can make the tractor brake relatively smoothly, and the first front and rear brake and the second front and rear brake can brake the wheels on both sides of the tractor respectively. It should be noted here that the first brake valve 12, the second brake valve 23, the first front and rear brake and the second front and rear brake can all be components in the prior art, and those skilled in the art can make reasonable selections according to the vehicle model and vehicle design of the tractor.

[0039] Preferably, if Figure 1 and Figure 3 As shown, in the embodiment, the first control valve 27 is connected in parallel with the second one-way valve 9 and the third one-way valve 26. The solenoid valve group includes a first solenoid valve 22 and a second solenoid valve 21. The first control valve 27 is connected to the first front and rear brakes through the first solenoid valve 22, and the first control valve 27 is connected to the second front and rear brakes through the second solenoid valve 21. The first control valve 27 can output different pressures, which are then transmitted to the first front and rear brakes or the second front and rear brakes through the solenoid valves.

[0040] Preferably, if Figure 1 and Figure 3 As shown, in the embodiment, the first pressure sensor group library includes a first pressure sensor 13 and a second pressure sensor 19, the first pressure sensor 13 is connected to the first solenoid valve 22, the second pressure sensor 19 is connected to the second solenoid valve 21, and the first pressure sensor 13 and the second pressure sensor 19 are used to detect the actual value of the auxiliary brake pressure, thereby facilitating the input signal controlled by the first control valve 27. The first solenoid valve 22 is connected to the first front and rear brakes through the fourth one-way valve 14, and the second solenoid valve 21 is connected to the second front and rear brakes through the fifth one-way valve 20.

[0041] Preferably, if Figure 1 and Figure 3As shown, in the embodiment, the one-way valve group also includes an accumulator group, a second pressure sensor group, a second overflow valve 30 and a unloading valve 29, the first pump assembly 31 is connected to the second overflow valve 30 and the unloading valve 29, the second overflow valve 30 and the unloading valve 29 are connected to the accumulator group so that the accumulator group starts to fill or stops filling; the second pressure sensor group is connected to the accumulator group to feedback the condition of the accumulator at this time. Specifically, the accumulator group may include a first accumulator 10 and a second accumulator 28, the second pressure sensor group may include a third pressure sensor 11 and a fourth pressure sensor 25, the first accumulator 10 and the third pressure sensor 11 may be arranged in the same branch with the first brake valve 12, the first front brake 15 and the first rear brake 16, the second accumulator 28 and the fourth pressure sensor 25 may be arranged in the same branch with the second brake valve 23, the second front brake 18 and the second rear brake 17, the accumulator group may convert part of the energy in the system into compression energy or potential energy and store it, and then release it when needed to help maintain the stability of the system pressure. The third pressure sensor 11 and the fourth pressure sensor 25 are used to detect the set filling start pressure and the filling stop pressure of the accumulator respectively. When the accumulator is lower than the filling set pressure, the pressure switch is triggered, the unloading valve 29 loses power, and the first pump assembly 31 fills the accumulator through the first one-way valve 8. When the accumulator reaches the filling stop pressure, the other pressure switch is triggered, the unloading valve 29 is energized, and the first pump assembly 31 unloads through the unloading valve 29.

[0042] Preferably, in the embodiment, the first pressure sensor 13 , the second pressure sensor 19 , the third pressure sensor 11 and the fourth pressure sensor 25 may be, for example, strain gauge pressure sensors, piezoresistive pressure sensors, capacitive pressure sensors and piezoelectric pressure sensors.

[0043] Preferably, if Figure 1 and Figure 2 As shown, in the embodiment, the steering brake hydraulic system also includes a conventional steering system and a controller (not shown), and the controller can be a whole machine controller of the tractor. The controller can switch the tractor between the conventional steering system and the automatic auxiliary steering system, for example, a mode switching switch (not shown) is provided, and the mode switching switch is connected to the controller. The user selects the control mode of the tractor at this time through the mode switch.

[0044] Preferably, if Figure 1 As shown, in the embodiment, the conventional steering system and the automatic assisted steering system are arranged in parallel.

[0045] Preferably, if Figure 1 and Figure 2As shown, in the embodiment, the conventional steering system includes a second pump assembly 1 for outputting pressure, a steering control unit for controlling the output pressure, and a steering execution unit for steering the tractor, and the second pump assembly 1 is connected to the steering execution unit through the steering control unit. The second pump assembly 1 can extract hydraulic fluid from the oil tank 32 and deliver the hydraulic fluid to the steering control unit and the steering execution unit to steer the tractor, and the second pump assembly 1 can be a variable displacement pump.

[0046] Preferably, if Figure 1 and Figure 2 As shown, in the embodiment, the steering control unit includes a priority valve 3; the steering execution unit includes a steering gear 5, a first steering cylinder 6 and a second steering cylinder 7; the second pump assembly 1 is connected to the steering gear 5 through the priority valve 3, the first steering cylinder 6 and the second steering cylinder 7 are connected in parallel, and the first steering cylinder 6 and the second steering cylinder 7 are both connected in series with the steering gear 5, and the steering gear 5 can drive the first steering cylinder 6 or the second steering cylinder 7, so that the left or right wheel of the tractor rotates.

[0047] Preferably, if Figure 1 and Figure 2 As shown, in the embodiment, the steering control unit also includes a shuttle valve group 4, which is arranged before the priority valve 3 and the steering gear 5. The shuttle valve group 4 includes a first input port connected to the second pump assembly 1 for receiving load pressure, a second input port that can be connected to the working hydraulic system (not shown, the working hydraulic system is connected to the EF port) to receive feedback pressure from the working hydraulic system, and an output port for transmitting the larger of the pressures at the first input port and the second input port to the second pump assembly 1 to control the operation of the second pump assembly 1.

[0048] Preferably, if Figure 1 and Figure 2 As shown, in the embodiment, the steering control unit further comprises a first overflow valve 2 connected to the second pump assembly 1. The first overflow valve 2 can prevent the hydraulic oil pressure in the hydraulic system from exceeding the rated load, thus playing a role of safety protection.

[0049] Specifically, when the steering wheel of the tractor drives the steering gear 5 to rotate, the second pump assembly 1 outputs high-pressure oil into the steering gear 5 through the CF port of the priority valve 3, and then flows into the first steering cylinder 6 and the second steering cylinder 7, thereby further driving the articulated frame and the front frame to rotate relative to each other to achieve articulated steering. The load pressure during the steering process is fed back to the LS feedback port of the second pump assembly 1 through the LS2 port and the shuttle valve group 4, so that the output pressure of the second pump assembly 1 is equal to the load pressure + LS set pressure difference value. The EF port of the oil tank 32 is connected to the working hydraulic system. When the working hydraulic multi-way valve is actuated, part of the high-pressure oil is supplied to the working hydraulic system through the EF port, and at the same time, the load pressure of the working hydraulic system is fed back to the LS port of the second pump assembly 1 after selection through the LS1 port and the shuttle valve group 4. The shuttle valve group 4 selects the high pressure of the working hydraulic system and the steering load and feeds it back to the second pump assembly 1 to achieve the control of the second pump assembly 1.

[0050] The use process of the steering brake hydraulic system is as follows: when in the auxiliary brake steering mode, the automatic auxiliary steering function of the tractor can be realized through the following steps.

[0051] In the first step, an angle sensor is used to detect the current steering angle of the tractor, and the current steering angle is set to β. The angle sensor can be set on the articulated pin shaft to feed back the angle value by detecting the rotation angle between the articulated frame and the front frame, or a magnetic telescopic sensor built into or external to the steering cylinder can be used to detect the extension length of the piston rod. In addition, the following controller (not shown) can calculate the steering angle of the entire tractor according to the detected angle value or extension length and the parameters of the overall steering structure of the tractor.

[0052] The second step is to set the threshold α of the auxiliary braking steering angle, 0≤α≤maximum steering angle value βmax, α is the threshold of the auxiliary braking steering angle, and the operator can set different steering angle thresholds according to the situation. At this time, the second control valve 24 is energized and the control current is maximum, the second control valve 24 is completely in the right position, and the opening is maximum;

[0053] Step 3: When β≥α, the solenoid valve group is energized, and the controller calculates the pressure that the first control valve 27 needs to output according to the current steering angle β and the set steering angle threshold α. The pressure flows to the brake unit through the solenoid valve group, so that the brake unit brakes and limits the rotation speed of the wheel on one side.

[0054] The fourth step is that according to the drive axle differential theory, 2× drive axle input speed = left wheel speed + right wheel speed, and then the wheel speed on one side is limited to gradually decrease until it reaches zero, and then the wheel speed on the other side is increased according to the drive axle differential theory until the wheel speed increases to 2× drive axle input speed, thereby achieving a larger left and right wheel speed difference at the same steering angle than conventional steering, and achieving a smaller turning radius;

[0055] Step 5: When the steering angle β continues to increase, according to the relationship between the auxiliary brake pressure and the steering angle, the auxiliary brake pressure P f =k×P max ×(β-α) / (β max -α);

[0056] Where: P f is the auxiliary brake pressure, i.e., controls the output value of the first control valve 27;

[0057] K is the linear sensitivity coefficient of auxiliary braking and steering angle, which is a fixed value and can be set to different values ​​according to the whole tractor;

[0058] P max When the tractor is equipped with auxiliary equipment, the tire rolling resistance is calculated according to the field working conditions, and then the brake pressure bar required when one side of the wheel is locked is calculated based on the rolling resistance. It can also be set by the whole machine.

[0059] β is the current steering angle;

[0060] α is the auxiliary braking steering angle threshold. The operator can set different steering angle thresholds according to the situation, 0≤α value≤maximum steering angle value βmax;

[0061] β max It is the maximum steering angle, which is determined by the steering mechanism of the whole machine.

[0062] In the sixth step, the controller increases the control current of the first control valve 27 to output a larger auxiliary braking pressure, which flows to the brake unit, so that the wheel on one side is braked, further limiting the rotation speed of the wheel on one side, increasing the rotation speed of the wheel on the other side, achieving a larger rotation speed difference, and thus achieving a smaller turning radius.

[0063] Preferably, in an embodiment, the use process of the steering brake hydraulic system may further include the following steps for adjusting the auxiliary brake pressure.

[0064] In the first step, when the steering angle β ≥ α and β is gradually increasing, the second control valve 24 is energized and the control current is kept at the maximum, and the second control valve 24 is completely in the right position;

[0065] When the steering angle β changes from large to small and β≥α, the controller reduces the control current of the first control valve 27 according to the relationship algorithm between the auxiliary brake pressure and the steering angle, so as to output a smaller auxiliary brake pressure. At the same time, the second control valve 24 is energized and the control current is kept gradually decreasing from the current value, so that the second control valve 24 is in a state between the left position and the right position, thereby opening part of the channel between the brake pipeline and the oil tank 32, so that the oil in the brake pipeline is throttled and depressurized through the throttling effect of the second control valve 24, thereby reducing the auxiliary brake pressure.

[0066] In the second step, the first pressure sensor group is used to assist in detecting the actual value of the brake pressure and to control the input signal of the current size of the second control valve 24, thereby controlling the opening amplitude of the second control valve 24 to achieve the required auxiliary brake pressure;

[0067] In the third step, the first control valve 27 outputs a smaller auxiliary braking pressure, which flows to the brake of one wheel, changes the synovial pressure of the brake friction pad, thereby adjusting the rotation speed of one wheel, and realizing auxiliary braking steering with different speed differences.

[0068] Preferably, in an embodiment, the steering brake hydraulic system may further include an auxiliary brake steering mode and a normal steering mode that can be switched to each other, and a user can select the auxiliary brake steering mode or the normal steering mode through a mode switch connected to the controller.

[0069] The steering brake hydraulic system may further include the following steps for determining whether the user requires the entire vehicle to be braked.

[0070] The first step is that in the auxiliary brake steering mode, when the tractor's whole machine sensor detects that the user steps on the brake pedal, the controller determines that the whole tractor needs to be braked, the control current of the first control valve 27 is minimum, the output pressure is 0, the second control valve 24 loses power, the solenoid valve group loses power, the auxiliary brake pressure in the brake pipeline is released, and the brake system pressure enters the brake unit, so that the whole tractor is braked;

[0071] The second step is to cancel the auxiliary braking steering mode when the user steps on the brake pedal; when the user takes his foot off the brake pedal and does not brake, the normal steering mode is defaulted and the user can re-enter the auxiliary braking steering mode through the mode switch connected to the controller.

[0072] Preferably, when the user selects the conventional steering mode, when the user rotates the steering wheel to drive the steering gear 5 to rotate, the second pump assembly 1 outputs high-pressure oil into the steering gear 5 through the CF port of the priority valve 3, and then flows into the first steering cylinder 6 and the second steering cylinder 7, thereby further driving the articulated frame and the front frame to rotate relative to each other to realize articulated steering. In this mode, the user is required to independently control the steering of the tractor.

[0073] Preferably, when the user selects the auxiliary braking steering mode, taking right steering as an example (i.e., the first front brake 15 and the first rear brake 16 are actuated to brake the wheels on that side), when the whole machine steering angle β ≥ α value (auxiliary braking steering angle threshold, the operator can set different steering angle thresholds according to the situation, 0 ≤ α value ≤ maximum steering angle value βmax) is detected, the first solenoid valve 22 is energized, the first solenoid valve 22 is in the left position, and at the same time the second control valve 24 is energized and the control current is maximum, and the second control valve 24 is completely in the right position.

[0074] The whole machine controller calculates the required output pressure of the first control valve 27 according to the current steering angle β and the set steering angle threshold α, and then controls the current of the first control valve 27 to achieve the corresponding pressure output. The pressure flows through the left position of the first solenoid valve 22 and then flows through the fourth one-way valve 14 to the brake of the right wheel (i.e., the first front brake 15 and the first rear brake 16), thereby limiting the rotation speed of the right front and rear wheels. Because the left and right wheels of the bridge achieve differential speed through the differential, according to the bridge differential theory, 2 times × the input speed of the bridge = the left wheel speed + the right wheel speed. Therefore, when the right wheel speed is limited to become smaller or even zero, the left wheel speed becomes faster according to the differential theory, even to 2 × the input speed of the bridge, thereby achieving a larger left and right wheel speed difference at the same steering angle than conventional steering, and achieving a smaller turning radius.

[0075] When the steering wheel controls the steering gear 5 to continue steering and the steering angle β continues to increase, the controller increases the control current of the first control valve 27 according to the relationship algorithm between the auxiliary braking pressure and the steering angle to output a larger auxiliary braking pressure to flow to the brakes of the front and rear wheels on the right side (i.e., the first front brake 15 and the first rear brake 16) through the fourth one-way valve 14, further limiting the rotation speed of the front and rear wheels on the right side, increasing the rotation speed of the wheels on the other side, achieving a larger rotation speed difference, and thus achieving a smaller turning radius.

[0076] When the steering angle β changes from large to small and β≥α, the controller reduces the control current of the first control valve 27 according to the relationship algorithm between the auxiliary brake pressure and the steering angle to achieve the output of a smaller auxiliary brake pressure; at the same time, the second control valve 24 is energized and the control current is kept gradually reduced from the current value, so that the second control valve 24 is in a state between the left position and the right position, and then the partial channel between the brake pipeline and the oil tank 32 is opened, so that the oil in the brake pipeline is throttled and depressurized through the throttling effect of the second control valve 24, thereby reducing the auxiliary brake pressure; the first pressure sensor 13 is used to detect the actual value of the auxiliary brake pressure, and is used to control the input signal of the current size of the second control valve 24, thereby controlling the opening amplitude of the second control valve 24 to achieve the required auxiliary brake pressure. At the same time, the first control valve 27 outputs a smaller auxiliary brake pressure to flow to the brakes of the front and rear wheels on the right side through the fourth one-way valve 14, changing the synovial pressure of the brake friction pad, thereby achieving the speed adjustment of the front and rear wheels on the right side, and achieving auxiliary brake steering with different speed differences.

[0077] During the auxiliary braking and steering process, when the whole machine sensor detects that the brake pedal is stepped on, the controller determines that the whole tractor needs to brake. At this time, the control current of the first control valve 27 is minimum and the output pressure is 0; and the second control valve 24 is powered off and in the left position, the first solenoid valve 22 is powered off, and the first solenoid valve 22 is in the right position, the auxiliary braking pressure in the brake pipeline is released, and the braking system pressure enters the brake pipeline and the brake through the upper position of the first brake valve 12 to achieve vehicle braking; during the foot braking process, the auxiliary braking and steering mode is canceled; when the foot is off the brake pedal and no braking is performed, the whole machine defaults to the normal steering mode; when the auxiliary braking and steering mode is needed, the auxiliary braking and steering mode must be entered again by selecting the mode switch.

[0078] The steering brake hydraulic system can assist the operator in making small-radius turns through the first module and the second module of the automatic assisted steering system. It does not require the driver to have high driving experience and rich driving skills, and can cope with various working conditions in field operations to ensure operation safety.

[0079] Finally, it should be noted that the above-described embodiments are only specific implementation methods of the present application, which are used to illustrate the technical solutions of the present application, rather than to limit them. The protection scope of the present application is not limited thereto. Although the present application is described in detail with reference to the above-described embodiments, ordinary technicians in the field should understand that any technician familiar with the technical field can still modify the technical solutions recorded in the above-described embodiments within the technical scope disclosed in the present application, or can easily think of changes, or make equivalent replacements for some of the technical features therein; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A steering brake hydraulic system for a tractor, characterized in that: The steering brake hydraulic system includes an automatic assisted steering system, the automatic assisted steering system includes a first module and a second module, the first module is connected to the second module; The first module includes a first pump assembly for outputting pressure, a one-way valve group for controlling flow direction, and a brake unit for braking the tractor, wherein the first pump assembly is connected to the brake unit through the one-way valve group, and the first pump assembly can drive the brake unit to achieve braking through the one-way valve group; The second module includes a first control valve, a solenoid valve group and an angle sensor. The angle sensor is arranged on the tractor to detect the steering angle of the tractor. The angle sensor is connected to the first control valve. The first pump assembly is connected to the first control valve through the one-way valve group. The first control valve is connected to the brake unit through the solenoid valve group. The angle fed back by the angle sensor causes the first control valve to output different pressures to control the brake unit to achieve corresponding braking.

2. The steering brake hydraulic system according to claim 1, characterized in that: The second module also includes a second control valve and a first pressure sensor group. The first pressure sensor group is arranged in the braking unit for detecting the pressure value. The second control valve is arranged between the one-way valve group and the braking unit. The second control valve is connected to the first pressure sensor group and the braking unit. The value fed back by the first pressure sensor group enables the second control valve to adjust the output pressure to adjust the auxiliary braking pressure.

3. The steering brake hydraulic system according to claim 2, characterized in that: The first control valve is a proportional pressure reducing valve, and the second control valve is a proportional solenoid valve.

4. The steering brake hydraulic system according to claim 2, characterized in that: The steering brake hydraulic system also includes a conventional steering system and a controller, wherein the controller is capable of switching the tractor between the conventional steering system and the automatic assisted steering system, wherein the conventional steering system and the automatic assisted steering system are arranged in parallel; The conventional steering system includes a second pump assembly for outputting pressure, a steering control unit for controlling the output pressure, and a steering execution unit for steering the tractor, wherein the second pump assembly is connected to the steering execution unit through the steering control unit.

5. The steering brake hydraulic system according to claim 4, characterized in that: The one-way valve group includes a first one-way valve, a second one-way valve and a third one-way valve, the second one-way valve and the third one-way valve are connected in parallel, the second one-way valve and the third one-way valve are connected in series with the first one-way valve, and the first one-way valve is connected to the first pump assembly; The steering control unit includes a priority valve; the steering execution unit includes a steering gear, a first steering cylinder and a second steering cylinder; the second pump assembly is connected to the steering gear through the priority valve, the first steering cylinder and the second steering cylinder are connected in parallel, and the first steering cylinder and the second steering cylinder are both connected in series with the steering gear; The steering control unit also includes a shuttle valve group, which is arranged before the priority valve and the steering gear. The shuttle valve group includes a first input port connected to the second pump assembly for receiving load pressure, a second input port that can be connected to the working hydraulic system to receive feedback pressure from the working hydraulic system, and an output port for transmitting the larger of the pressures at the first input port and the second input port to the second pump assembly to control the operation of the second pump assembly.

6. The steering brake hydraulic system according to claim 5, characterized in that: The brake unit includes a first brake valve, a second brake valve, a first front and rear brake, and a second front and rear brake. The first front and rear brake is connected to the second one-way valve through the first brake valve, and the second front and rear brake is connected to the third one-way valve through the second brake valve.

7. The steering brake hydraulic system according to claim 6, characterized in that: The first control valve is connected in parallel with the second one-way valve and the third one-way valve, the solenoid valve group includes a first solenoid valve and a second solenoid valve, the first control valve is connected to the first front and rear brakes through the first solenoid valve, and the first control valve is connected to the second front and rear brakes through the second solenoid valve; The first pressure sensor group includes a first pressure sensor and a second pressure sensor, the first pressure sensor is connected to the first solenoid valve, and the second pressure sensor is connected to the second solenoid valve.

8. The steering brake hydraulic system according to claim 7, characterized in that: The first pressure sensor and the second pressure sensor are one of a strain gauge pressure sensor, a piezoresistive pressure sensor, a capacitive pressure sensor and a piezoelectric pressure sensor.

9. The steering brake hydraulic system according to claim 6, characterized in that: The one-way valve group also includes an accumulator group, a second pressure sensor group, a second overflow valve and a unloading valve. The first pump assembly is connected to the second overflow valve and the unloading valve. The second overflow valve and the unloading valve are connected to the accumulator group so that the accumulator group starts to fill or stops filling. The second pressure sensor group is connected to the accumulator group to feedback the condition of the accumulator at this time.

10. The steering brake hydraulic system according to claim 9, characterized in that: The accumulator group includes a first accumulator and a second accumulator, the second pressure sensor group includes a third pressure sensor and a fourth pressure sensor, The first accumulator is connected to the third pressure sensor, the first brake valve, and the first front and rear brake, and the second accumulator is connected to the fourth pressure sensor, the second brake valve, and the second front and rear brake.

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