A steering hydraulic system applied to a multi-axle vehicle and a control method thereof

Abstract

The application discloses a kind of steering hydraulic system and control method applied to multi-axle vehicle, belong to vehicle technical field.The steering system includes frame, front axle, rear axle, engine, steering wheel, control mechanism, actuating mechanism, the both ends of front axle are equipped with front wheel, the both ends of rear axle are equipped with rear wheel, actuating mechanism includes hydraulic cylinder, hydraulic cylinder is located on rear axle, control mechanism is located on frame or rear axle, control mechanism is used to receive engine speed information, steering wheel angle information, front wheel angle information, rear wheel angle information, vehicle speed information, the displacement information of hydraulic cylinder piston rod, and the extension of control hydraulic cylinder.The application can improve the mobility of multi-axle vehicle, reduce the use cost of multi-axle vehicle, improve the adaptability of multi-axle vehicle to road, help the popularization and use of multi-axle vehicle.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of vehicles, in particular to a steering hydraulic system applied to a multi-axle vehicle and a control method thereof. BACKGROUND

[0002] With the development of society and the progress of science and technology, the demand for large vehicles is increasing. In order to protect the road surface from serious damage, the state has limited the size and weight of all large vehicles. In order to improve the steering and lifting capacity, the traditional large vehicle axial configuration can not meet the needs of the vehicle by only increasing the axial size and strength, so the multi-axle vehicle emerges as the times require.

[0003] The use of the multi-axle vehicle has the following defects:

[0004] Firstly, because the wheelbase of the multi-axle vehicle is long, the rear axle cannot be actively steered, so the maneuverability is lacking during steering;

[0005] Secondly, because the rear axle of the multi-axle vehicle cannot be actively steered, the multi-axle vehicle has a large steering radius, which increases tire wear and leads to an increase in the use cost of the vehicle;

[0006] Thirdly, because the multi-axle vehicle has a large steering radius, the multi-axle vehicle needs more space when steering, and because the traffic infrastructure in underdeveloped areas lacks straight and wide roads, the multi-axle vehicle is difficult to adapt to the narrow and not straight roads in this area, thereby reducing the adaptability of the multi-axle vehicle to the road;

[0007] The above-mentioned defects of the multi-axle vehicle are not conducive to the popularization and use of the multi-axle vehicle. SUMMARY

[0008] The present application is aimed at the above-mentioned deficiencies in the prior art, and provides a steering hydraulic system applied to a multi-axle vehicle and a control method thereof, which can improve the maneuverability of the multi-axle vehicle, reduce the use cost of the multi-axle vehicle, improve the adaptability of the multi-axle vehicle to the road, and help the popularization and use of the multi-axle vehicle.

[0009] To achieve the above-mentioned purpose, the present application provides the following technical scheme:

[0010] A steering hydraulic system applied to a multi-axle vehicle, comprising a vehicle frame, a front axle, a rear axle, an engine, a steering wheel, a control mechanism, and an actuating mechanism, both ends of the front axle are provided with front wheels, both ends of the rear axle are provided with rear wheels, a hydraulic cylinder is arranged on the rear axle, the control mechanism is arranged on the vehicle frame or the rear axle, the control mechanism is used for receiving engine speed information, steering wheel angle information, front wheel angle information, rear wheel angle information, vehicle speed information, and displacement information of a hydraulic cylinder piston rod, and controlling the extension and retraction of the hydraulic cylinder.

[0011] Further, the control mechanism adopts a first control mechanism, the first control mechanism is arranged on the frame, the first control mechanism includes an ECU controller, a servo motor, a gear pump, an oil tank, a check valve, a control valve, a hydraulic pipe, a sensor; the ECU controller is used for receiving engine speed information, steering wheel angle information, front wheel angle information, rear wheel angle information, vehicle speed information, displacement information of the hydraulic cylinder piston rod, and controlling the servo motor to run; the servo motor is used for driving the gear pump to run; the gear pump is used for pumping hydraulic oil in the oil tank; the oil tank is used for storing hydraulic oil; the check valve is used for controlling the one-way flow of hydraulic oil in the oil tank; in the hydraulic cylinder extension and retraction process, the control valve is used for controlling the hydraulic cylinder oil return port on the hydraulic cylinder to be closed, and in the hydraulic cylinder maintaining the middle state, the control valve is used for controlling the hydraulic cylinder oil return port on the hydraulic cylinder to be opened to drain oil; the hydraulic pipe is used for connecting the oil tank and the hydraulic cylinder, the control valve and the hydraulic cylinder, and the control valve and the oil tank; the sensor is used for detecting the displacement information of the hydraulic cylinder piston rod and transmitting the displacement information of the hydraulic cylinder piston rod to the ECU controller.

[0012] Further, the first control mechanism further includes a shaft coupling and a connecting disc, the ECU controller is arranged at the end of the servo motor, the output end of the servo motor is connected to the input end of the gear pump through the shaft coupling, the gear pump is connected to the oil tank through the connecting disc, the inside of the oil tank is provided with the check valve, the control valve is arranged on the shaft coupling, and the sensor is arranged on the hydraulic cylinder.

[0013] Further, the sensor adopts a microelectronic optical sensor, and the microelectronic optical sensor is arranged in the hydraulic cylinder.

[0014] Further, the control mechanism adopts a second control mechanism, the second control mechanism is arranged on the rear axle, and the second control mechanism includes the ECU controller, the servo motor, the shaft coupling, the gear pump, the connecting disc, the oil tank, the check valve, the control valve, the sensor, and an integrated valve block; the integrated valve block replaces the hydraulic pipe, the shaft coupling, the gear pump, the connecting disc, and the control valve are arranged in the integrated valve block, and the integrated valve block is connected to the hydraulic cylinder.

[0015] A control method applied to a steering hydraulic system of a multi-axle vehicle, comprising the following steps: the control mechanism calculates whether the absolute value of the front wheel steering angle is less than or equal to 3°, when the absolute value of the front wheel steering angle is less than or equal to 3°, the control mechanism controls the hydraulic cylinder to keep the middle state, so that the rear wheel is straight and does not turn; when the absolute value of the front wheel steering angle is greater than 3°, the control mechanism judges whether the vehicle speed is less than 45Km / h and the rear wheel steering angle speed is less than or equal to 8° / s, when the vehicle speed is greater than or equal to 45Km / h or the rear wheel steering angle speed is greater than or equal to 8° / s, the control mechanism controls the hydraulic cylinder to keep the middle state, so that the rear wheel is straight and does not turn; when the vehicle speed is less than 45Km / h and the rear wheel steering angle speed is less than or equal to 8° / s, the control mechanism controls the hydraulic cylinder piston rod to extend, so that the steering direction of the rear wheel is opposite to that of the front wheel.

[0016] Further, when the steering system fails or is damaged, the control mechanism controls the hydraulic cylinder to keep the middle state.

[0017] Further, when the control mechanism successfully receives the error-free signal again, the steering system is out of failure and normally operates.

[0018] Compared with the prior art, the application has the following beneficial effects:

[0019] 1. In the steering system of the application, the control mechanism can control the hydraulic cylinder in the execution mechanism to respond according to the steering angle and vehicle speed of the front axle and other information, so that the rear axle equipped with the hydraulic cylinder can complete active steering, and the maneuverability of the multi-axle vehicle is improved.

[0020] Because the active steering of the rear axle can be realized, the multi-axle vehicle can reduce the steering radius, reduce tire wear, prolong the service life, and reduce the use cost of the multi-axle vehicle.

[0021] Because the steering radius of the multi-axle vehicle can be reduced, the multi-axle vehicle can be applied to roads that are not wide and straight, and the adaptability to roads is improved.

[0022] In summary, the steering system of the application improves the maneuverability of the multi-axle vehicle, reduces the use cost of the multi-axle vehicle, improves the adaptability of the multi-axle vehicle to roads, and is conducive to the popularization and use of the multi-axle vehicle.

[0023] 2. The steering system provided by the application can use an integrated valve block instead of a hydraulic pipe, so that the control mechanism and the execution mechanism can be integrated into an integrated structure, the integration degree is improved, the space occupied by the vehicle frame is reduced, the arrangement and installation of other equipment on the vehicle frame are more convenient, and the use flexibility of the application is improved. BRIEF DESCRIPTION OF DRAWINGS

[0024] ATTACH Figure 1 It is an overall structure schematic diagram of the application.

[0025] Figure 1 Figure 2 Structure diagram of the control mechanism and hydraulic cylinder of Example 1;

[0026] Figure 2 Figure 3 Structure diagram of the control mechanism of Example 1;

[0027] Figure 3 Figure 4 Structure diagram of the control mechanism of Example 1 with the oil tank cutaway;

[0028] Figure 4 Figure 5 Structure diagram of the hydraulic cylinder of Example 1 with the microelectronic optical sensor built-in;

[0029] Figure 5 Figure 6 Interface diagram of the control valve, ECU controller, and oil tank of Example 1 or Example 2;

[0030] Figure 6 Figure 7 Interface diagram of the hydraulic cylinder of Example 1 or Example 2.

[0031] Figure 7 Figure 8 Structure diagram of the control mechanism and hydraulic cylinder of Example 2;

[0032] Figure 8 Figure 9 Structure diagram of the control mechanism of Example 2 without the integrated valve block;

[0033] Figure 9 Figure 10 Structure diagram of the control mechanism of Example 2 without the integrated valve block and with the oil tank cutaway; Figure 10 Figure 11 Structure diagram of the hydraulic cylinder of Example 2 with the microelectronic optical sensor built-in;

[0034] Figure 11 Figure 12 Hydraulic principle diagram of Example 1, 2;

[0035] Figure 12 Figure 13 Schematic diagram of the front-wheel steering mode;

[0036] Figure 13 Figure 14 Schematic diagram of the reverse-phase steering mode;

[0037] Figure 14 Figure 15 Control method principle diagram;

[0038] Figure 15 Figure 16 Figure 16 Figure 15 Enlarged view of A in Figure 16;

[0039] Figure 17 Figure 17 Figure 18 Figure 15 Enlarged view of B in Figure 18;

[0040] Figure 19 Figure 18 Figure 20 Figure 15 Enlarged view of C in Figure 20;

[0041] Attachment Figure 19 is the relationship diagram between steering wheel angle and front wheel angle;

[0042] Attachment Figure 20 is the relationship diagram between the front wheel angle and the rear wheel angle;

[0043] Attachment Figure 21 is the relationship diagram between the target displacement of the hydraulic cylinder piston rod and the rear wheel angle;

[0044] Attachment Figure 22 This is the calculation process diagram for the target displacement S of the hydraulic cylinder piston rod to the target speed N of the servo motor.

[0045] In the picture:

[0046]

[0047] DETAILED DESCRIPTION

[0048] The following will clearly and completely describe the technical solutions in the embodiments of the present invention 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 making creative efforts are within the scope of protection of the present invention.

[0049] Example 1:

[0050] A steering hydraulic system applied to a multi-axle vehicle comprises a vehicle frame, a front axle, a rear axle, an engine, a steering wheel, a control mechanism, and an actuator.

[0051] Axles, also known as axles, are connected to the vehicle frame via suspension. Wheels are mounted on either end of the axle, and the axle is used to transmit forces and torques in all directions between the frame and the wheels. If there are N axles on a vehicle frame, there are N axles (N is a natural number greater than 3).

[0052] like Figure 1 As shown, when N=5, there are 5 axles on the vehicle frame 10. These 5 axles are respectively denoted as the first axle 11, the second axle 12, the third axle 13, the fourth axle 14, and the fifth axle 15 from the front to the rear of the vehicle.

[0053] like Figure 1As shown, the first axle 11 is driven by the steering wheel. The second axle 12 is close to the first axle 11, so the second axle 12 is connected to the first axle 11 by a tilt linkage 16 and is driven by the first axle 11. The third axle 13 is far from the second axle 12, so the third axle 13 cannot be connected to the second axle 12 by a tilt linkage. The first axle 11 and the second axle 12 are front axles, and the third axle 13 and the axles behind the third axle 13 are rear axles. The wheels at the two ends of the front axles are front wheels, and the wheels at the two ends of the rear axles are rear wheels.

[0054] In order to distinguish the structure of the embodiment 1 from the structure of the embodiment 2, the structure of the embodiment 1 is marked with "a" and the structure of the embodiment 2 is marked with "b".

[0055] As shown in the figure, the steering system of the embodiment 1 includes an actuator, a control mechanism, and a sensor. Figures 1-2 As shown in the figure, the actuator of the steering system of the embodiment 1 includes hydraulic cylinders 20a, which are installed on the third axle 13 and the fourth axle 14. The extension and retraction of the hydraulic cylinders 20a installed on the third axle 13 realize the steering and straightening of the wheels on the third axle 13. The extension and retraction of the hydraulic cylinders 20a installed on the fourth axle 14 realize the steering and straightening of the wheels on the fourth axle 14.

[0056] As shown in the figure, the control mechanism of the steering system of the embodiment 1 includes a first control mechanism, which is installed on the frame 10 near the third axle 13 and on the frame 10 near the fourth axle 14. Figure 1 As shown in the figure, the first control mechanism includes an ECU controller 31a, a servo motor 32a, a coupling 33a, a gear pump 34a, a connecting disc 35a, an oil tank 36a, a one-way valve 37a, a control valve 38a, a sensor, and hydraulic pipes 310. The sensor can be a microelectronic optical sensor 39a.

[0057] Figures 2-4 As shown in the figure, the ECU controller 31a is installed at the end of the servo motor 32a. The ECU controller 31a is used to receive engine speed information, steering wheel angle information, front wheel angle information, rear wheel angle information, vehicle speed information, displacement information of the hydraulic cylinder 20a piston rod, and control the operation of the servo motor 32a.

[0058] As shown in the figure, the output end of the servo motor 32a is connected to the input end of the gear pump 34a through the coupling 33a. The servo motor 32a is used to drive the gear pump 34a to operate. Figures 2-4 As shown in the figure, the output end of the gear pump 34a is connected to the connecting disc 35a through the hydraulic pipes 310. The gear pump 34a is used to drive the hydraulic cylinders 20a to operate.

[0059] Figures 2-4 As shown in the figure, the connecting disc 35a is connected to the one-way valve 37a. The one-way valve 37a is used to control the flow direction of the hydraulic oil in the oil tank 36a.

[0060] As shown in the figure, the one-way valve 37a is connected to the control valve 38a. The control valve 38a is used to control the flow direction of the hydraulic oil in the oil tank 36a. Figures 2-4 ​​As shown, the gear pump 34a is connected with the oil tank 36a through the connecting plate 35a. Specifically, as shown in Figure 4 As shown, the connecting plate 35a is provided with a connecting plate oil outlet 3501a, by which the oil tank 36a and the gear pump oil inlet 3401a are directly connected. The gear pump 34a is used to pump the hydraulic oil in the oil tank 36a.

[0061] As shown in Figures 2-4 As shown, the oil tank 36a is used to store the hydraulic oil required for the extension and retraction of the hydraulic cylinder 20a.

[0062] As shown in Figure 4 As shown, the oil tank 36a is internally provided with a one-way valve 37a. The one-way valve 37a is used to control the one-way flow of the hydraulic oil in the oil tank 36a, preventing backflow.

[0063] As shown in Figures 2-4 As shown, the control valve 38a is installed on the housing of the shaft coupling 33a. On the one hand, during the extension and retraction of the hydraulic cylinder 20a, the control valve 38a ensures that the hydraulic cylinder oil return port 2003a on the hydraulic cylinder 20a is closed; on the other hand, when the hydraulic cylinder 20a is in the neutral state, the control valve 38a controls the hydraulic cylinder oil return port 2003a on the hydraulic cylinder 20a to open and drain.

[0064] As shown in Figures 5-7 As shown, the micro-electronic optical sensor 39a is used to detect the displacement information of the piston rod of the hydraulic cylinder 20a. The micro-electronic optical sensor 39a is installed in the hydraulic cylinder 20a, and the micro-electronic optical sensor 39a is electrically connected with the ECU controller 31a. Specifically, the micro-electronic optical sensor 39a is sequentially connected through the sensor interface 2004a provided on the hydraulic cylinder 20a, the CAN bus, and the ECU sensor interface 3101a connected to the ECU controller 31a.

[0065] The hydraulic pipe fitting 310 is used to realize the connection of the hydraulic cylinder 20a and the control valve 38a, the connection of the hydraulic cylinder 20a and the oil tank 36a, and the connection of the control valve 38a and the oil tank 36a. Specifically, as shown in Figures 6-7 As shown, the hydraulic cylinder 20a is provided with a hydraulic cylinder oil inlet 2001a, a hydraulic cylinder oil outlet 2002a, and a hydraulic cylinder oil return port 2003a; the control valve 38a is provided with a control valve oil inlet 3801a and a control valve oil outlet 3802a; and the oil tank 38a is provided with an oil tank oil return port 3601a.

[0066] As shown in Figure 12As shown, the hydraulic oil delivered by the gear pump 34a is delivered to the hydraulic cylinder inlet 2001a through the hydraulic pipe 310, and is delivered to the hydraulic cylinder outlet 2002a through the hydraulic pipe 310. A branch of the hydraulic pipe 310 leading to the hydraulic cylinder inlet 2001a is connected to the control valve inlet 3801a of the first control valve 38a. A branch of the hydraulic pipe 310 leading to the hydraulic cylinder outlet 2002a is connected to the control valve inlet 3801a of the second control valve 38a. The control valve outlet 3802a of the first control valve 38a and the control valve outlet 3802a of the second control valve 38a are connected to the tank return 3601a through the hydraulic pipe 310. The connection end of the control valve outlet 3802a of the first control valve 38a and the control valve outlet 3802a of the second control valve 38a is also connected to the hydraulic cylinder return 2003a through the hydraulic pipe 310.

[0067] In the steering system of the embodiment 1, the ECU controller 31a receives the steering angle and the vehicle speed of the front two axles (i.e. the first axle 11 and the second axle 12) and controls the servo motor 32a to rotate. The servo motor 32a drives the gear pump 34a to suck the hydraulic oil in the tank 36a, and then delivers the hydraulic oil to the hydraulic cylinder 20a, so as to extend the hydraulic cylinder 20a and rotate the wheels on the third axle 13 and the fourth axle 14 by a certain angle. Meanwhile, the micro-electronic optical sensor 39a built in the hydraulic cylinder 20a feeds back the displacement of the piston rod of the hydraulic cylinder 20a to the ECU controller 31a in time. The ECU controller 31a responds in time, and the steering of the third axle 13 and the fourth axle 14 is completed.

[0068] From the above use process, it can be seen that:

[0069] In the steering system of the embodiment 1, the hydraulic cylinder 20a in the actuating mechanism is installed on the rear axle, and the control mechanism is installed on the vehicle frame 10 near the rear axle, so the actuating mechanism and the control mechanism are in a split structure.

[0070] In the steering system of the embodiment 1, the control mechanism can control the hydraulic cylinder 20a in the actuating mechanism to respond according to the steering angle and the vehicle speed of the front axle, so as to complete the active steering of the rear axle, and improve the maneuverability of the multi-axle vehicle.

[0071] Because the active steering of the rear axle can be realized, the multi-axle vehicle can reduce the steering radius, reduce the tire wear, prolong the service life, and reduce the use cost of the multi-axle vehicle.

[0072] Because the steering radius of the multi-axle vehicle can be reduced, the multi-axle vehicle can be applied to roads that are not wide and not straight, and the adaptability to roads is improved.

[0073] In summary, the steering system of the embodiment 1 improves the maneuverability of the multi-axle vehicle, reduces the use cost of the multi-axle vehicle, improves the adaptability of the multi-axle vehicle to the road, and is conducive to the popularization and use of the multi-axle vehicle.

[0074] Embodiment 2

[0075] The steering system of the embodiment 1 is applied to the third axle 13 and the fourth axle 14, and the steering system of the embodiment 2 is applied to the fifth axle 15.

[0076] As shown in Figure 1 and Figure 8 , in the steering system of the embodiment 2, the actuator includes a hydraulic cylinder 20b. The hydraulic cylinder 20b is installed on the fifth axle 15, and the extension and retraction strokes of the hydraulic cylinder 20b realize the steering and straightening of the wheels on the fifth axle 15 of the vehicle.

[0077] As shown in Figure 1 and Figure 8 , in the steering system of the embodiment 2, the control mechanism includes a second control mechanism, which is installed on the fifth axle 15. The second control mechanism includes an ECU controller 31b, a servo motor 32b, a shaft coupling 33b, a gear pump 34b, a connecting disc 35b, an oil tank 36b, a one-way valve 37b, a control valve 38b, a sensor, and an integrated valve block 311. The sensor is a microelectronic optical sensor 39b.

[0078] As shown in Figure 8 , the ECU controller 31b is installed at the end of the servo motor 32b. The ECU controller 31b is used to receive engine speed information, steering wheel angle information, front wheel angle information, rear wheel angle information, vehicle speed information, displacement information of the hydraulic cylinder 20b piston rod, and control the operation of the servo motor 32b.

[0079] As shown in Figures 9-10 , the output end of the servo motor 32b is connected with the input end of the gear pump 34b through the shaft coupling 33b. The servo motor 32b is used to drive the gear pump 34b to operate.

[0080] As shown in Figures 9-10 , the gear pump 34b is connected with the oil tank 36b through the connecting disc 35b. Specifically, as shown in Figure 10 , the connecting disc 35b is provided with a connecting disc oil outlet 3501b, and the oil tank 36b and the gear pump oil inlet 3401b are directly connected through the connecting disc oil outlet 3501b. The gear pump 34b is used to suck the hydraulic oil in the oil tank 36b.

[0081] As shown in Figures 8-10 , the oil tank 36b is used for the hydraulic oil required for the extension and retraction of the hydraulic cylinder 20b.

[0082] AsFigure 10 As shown, a one-way valve 37b is installed inside the oil tank 36b. The one-way valve 37b is used to control the one-way flow of the hydraulic oil in the oil tank 36b to prevent backflow.

[0083] like Figure 9 As shown, control valve 38b is mounted on the housing of coupling 33b. During the extension and retraction of hydraulic cylinder 20b, control valve 38b ensures that hydraulic cylinder return port 2003b on hydraulic cylinder 20b is closed. Furthermore, when hydraulic cylinder 20b remains in the neutral position, control valve 38b opens hydraulic cylinder return port 2003b on hydraulic cylinder 20b to drain oil.

[0084] like Figure 11 As shown, microelectronic optical sensor 39b is used to detect the displacement of hydraulic cylinder 20b. Microelectronic optical sensor 39b is installed inside hydraulic cylinder 20b and is electrically connected to ECU controller 31b. Specifically, microelectronic optical sensor 39b is connected to ECU sensor interface 3101b on ECU controller 31b via sensor interface 2004b provided on hydraulic cylinder 20b, the CAN bus, and finally the ECU sensor interface 3101b.

[0085] like Figure 8 As shown, the integrated valve block 311 houses the coupling 33b, the gear pump 34b, the connecting plate 35b, and the control valve 38b. The integrated valve block 311 is installed on the hydraulic cylinder 20b. The integrated valve block 311 can replace the hydraulic pipe 310 in Example 1 to achieve the connection between the hydraulic cylinder 20b and the control valve 38b, the connection between the hydraulic cylinder 20b and the oil tank 36b, and the connection between the control valve 38b and the oil tank 36b. Specifically, as shown in FIG. Figures 6-7 As shown, the hydraulic cylinder 20b is provided with a hydraulic cylinder oil inlet 2001b, a hydraulic cylinder oil outlet 2002b, and a hydraulic cylinder oil return port 2003b, the control valve 38b is provided with a control valve oil inlet 3801b, a control valve oil outlet 3802b, and the oil tank 38b is provided with an oil tank return port 3601b.

[0086] like Figure 12As shown, the hydraulic oil delivered by the gear pump 34b is delivered to the hydraulic cylinder inlet 2001b through the flow channel in the integrated valve block 311, and is delivered to the hydraulic cylinder outlet 2002b through the flow channel in the integrated valve block 311. A branch is split from the flow channel in the integrated valve block 311 leading to the hydraulic cylinder inlet 2001b and connected to the control valve inlet 3801b of the first control valve 38b. A branch is split from the flow channel in the integrated valve block 311 leading to the hydraulic cylinder outlet 2002b and connected to the control valve inlet 3801b of the second control valve 38b. The control valve outlet 3802b of the first control valve 38b and the control valve outlet 3802b of the second control valve 38b are connected together through the flow channel in the integrated valve block 311 and connected to the tank return port 3601b. The connection end of the control valve outlet 3802b of the first control valve 38b and the control valve outlet 3802b of the second control valve 38b is also connected to the hydraulic cylinder return port 2003b through the flow channel in the integrated valve block 311.

[0087] In operation, the steering system of this embodiment 2 receives the steering angle and vehicle speed information from the front two axles (i.e. the first axle 11 and the second axle 12) and controls the servo motor 32b to rotate, which drives the gear pump 34b to suck oil and deliver the hydraulic oil in the tank 36b to the hydraulic cylinder 20b, so as to extend the hydraulic cylinder 20b and rotate the wheels of the fifth axle 15 by a certain angle. At the same time, the micro-electronic optical sensor 39b built in the hydraulic cylinder 20b collects the displacement of the piston rod of the hydraulic cylinder 20b and sends it to the ECU controller 31b. The ECU controller 31b responds in time to complete the steering work of the fifth axle 15.

[0088] From the above process, it can be seen that:

[0089] The steering system provided by this embodiment 2 uses the integrated valve block 311 instead of the hydraulic pipe 310 in the steering system of embodiment 1, so as to integrate the control mechanism and the actuator into an integrated structure, improve the integration degree, and thus facilitate the reduction of the space occupied by the frame 10, the arrangement and installation of other devices on the frame 10, and the use flexibility.

[0090] Embodiment 3:

[0091] The steering system of embodiment 1 is used on the third axle 13 and the fourth axle 14 of the five-axle vehicle, and the steering system of embodiment 2 is used on the fifth axle 15 of the five-axle vehicle, so as to realize the mixed use of the steering system of embodiment 1 and the steering system of embodiment 2. In the mixed use, the steering processes of the third axle 13, the fourth axle 14 and the fifth axle 15 are performed synchronously, so as to complete the steering work of the whole vehicle.

[0092] In addition, the steering system of Embodiment 1 and the steering system of Embodiment 2 can also be used in place of each other.

[0093] If the vehicle steering rod space is small and the frame 10 is large, only the steering system of Embodiment 1 can be used on the third axle 13, the fourth axle 14, the fifth axle 15, the sixth axle, and the Nth axle.

[0094] If the vehicle frame 10 is small and compact, and cannot be installed on the frame 10, only the steering system of Embodiment 2 can be used on the third axle 13, the fourth axle 14, the fifth axle 15, the sixth axle, and the Nth axle.

[0095] Embodiment 4:

[0096] The front axle front wheels and the rear axle rear wheels of the vehicle have two steering modes, which are the front wheel steering mode as shown in Figure 13 and the reverse phase steering mode as shown in Figure 14 In the front wheel steering mode, the front wheels rotate and move, and the rear wheels are in a straight-ahead non-steering state, at which time the hydraulic cylinders 20a / b on the rear axle are in a neutral state. In the reverse phase steering mode, the steering directions of the front wheels and the rear wheels are opposite, at which time the hydraulic cylinder 20a / b piston rod on the rear axle is in an extended state.

[0097] A steering hydraulic system applied to a multi-axle vehicle, referred to as a steering system, has an initial starting process: referring to Figure 16 When the ECU controller 31a / b receives a message that the engine speed exceeds the preset speed 400 r / m i n , the above-mentioned steering system is activated. After the steering system is powered on, the rear wheels need to automatically follow the front wheels to rotate and compensate for the difference caused by the automatic rotation of the steering wheel, at which time the maximum rotation speed of the rear wheels is limited to 3° / s. The default steering mode of the steering system is the reverse phase steering mode. The steering system performs CANopen initialization, IO port initialization, sends bus heartbeat messages to check the on-off state of the circuit, calibrates sensor parameters, controls the power-on of the servo motor 32a / b, and detects whether the rear axle sensor signal is consistent with the front wheel rotation angle target (such as a parking state, the front wheels are in a left turning state, and then the sensor detects whether the hydraulic cylinder 20a / b piston rod is in an extended state).

[0098] In order to realize the acceptance of control signals and the sending of control instructions, the ECU controller 31a / b includes at least the following five kinds of messages:

[0099] ① The rear axle lifting position signal (ASC1) is sent by the ECAS: when the lifting instruction is sent, the steering is not turned.

[0100] ②Front axle vehicle speed signal (EBC2) is sent by EBS: provides vehicle speed information for the electrically controlled rear axle, is an important message, when the vehicle speed is greater than 45km / h, the rear axle does not turn.

[0101] ③Engine speed signal (EEC1) is sent by the engine: the engine immediately turns after ignition, this message is used to activate the steering system when the engine speed is greater than 400.

[0102] ④Steering wheel angle signal (SAS_SAS) is sent by the steering angle sensor.

[0103] ⑤VDHR mileage information message, sent from the instrument.

[0104] All signals have self-recovery function, that is, when the message is wrong at a certain time, the rear axle does not turn, and when the message returns to normal, the rear axle returns to the turning function. Due to the failure of ECU controller 31a / b, some messages are not sent, which also causes the rear axle not to turn.

[0105] A control method applied to a steering hydraulic system of a multi-axle vehicle, as shown in Figure 17 , comprising the following steps:

[0106] The ECU controller 31a / b calculates and judges whether the front wheel angle is within ±3°. If yes (i.e. the front wheel angle is within ±3°), the rear wheel does not turn, the steering system executes the front wheel steering mode, and plays the role of early correction. At this time, the ECU controller 31a / b only receives the steering wheel angle signal and does not calculate. The ECU controller 31a / b sends a voltage signal to the servo motor 31a / b, so that the hydraulic cylinder 20a / b remains in the middle position (at this time, the hydraulic cylinder 20a / b piston rod extends by a certain range). Through the sensor, the displacement signal of the hydraulic cylinder 20a / b piston rod is transmitted to the ECU controller 31a / b. The ECU controller 31a / b compares the actual displacement signal of the hydraulic cylinder 20a / b piston rod with the theoretical displacement signal to verify the middle position keeping effect of the hydraulic cylinder 20a / b.

[0107] If not (i.e. the front wheel angle is not within ±3°), the steering system first judges whether the vehicle speed is less than 45Km / h and the rear wheel angle speed is less than or equal to 8° / s in real time. If not, execute the above front wheel steering mode.

[0108] If yes (i.e. the vehicle speed is less than 45Km / h and the rear wheel angle speed is less than or equal to 8° / s), the steering system executes the reverse phase steering mode. The ECU controller 31a / b receives the steering wheel angle signal, calculates the front wheel angle from the steering wheel angle, and calculates the ideal front wheel angle according to the curve corresponding relationship as shown in Figure 19 . Then, the ideal front wheel angle is calculated according to the curve corresponding relationship as shown in Figure 20The ideal rear wheel turning angle is calculated based on the curve corresponding to the Figure 21 The curve relationship shown in FIG2 is used to calculate the target displacement S of the piston rod of the hydraulic cylinder 20a / b. The target displacement S of the piston rod of the hydraulic cylinder 20a / b is input and the formula (N=AS / V 排 t) to obtain the target speed N of the servo motor 32a / b (see Figure 22 The ECU controller 31a / b converts the target speed into a voltage signal, sends the voltage signal to the servo motor 32a / b, drives the gear pump 34a / b to supply oil, and then realizes the extension of the piston rod of the hydraulic cylinder 20a / b (the hydraulic cylinder 20a / b converts the extension amount of the piston rod into an angle of the rear wheel). The built-in sensor of the piston rod of the hydraulic cylinder 20a / b transmits the information to the ECU controller 31a / b via the CAN bus. The ECU controller 31a / b compares the actual displacement signal of the piston rod of the hydraulic cylinder 20a / b with the theoretical displacement signal to verify the steering effect.

[0109] The steering system will only recognize that the switching conditions are effective and execute the corresponding switching request if the above switching conditions are met for more than 1 second.

[0110] The control method of the present invention presets response modes for abnormal situations such as steering system failure or damage, including emergency centering mode, automatic return mode, steering system self-recovery mode, servo motor 32a / b self-recovery mode, and steering error automatic correction mode. Figure 18 shown.

[0111] (1) Emergency centering mode: When the steering system fails, an alarm signal or fault code of the corresponding type and a fault code or diagnostic code of the corresponding position are sent to the ECU controller 31a / b, and the steering system immediately switches to the front-wheel steering mode, and the rear axle hydraulic cylinder 20a / b is locked in the centering state.

[0112] Steering system faults include vehicle speed message faults, engine speed message faults, steering wheel angle message faults, mileage information message faults, and ECU controller 31a / b faults. The above five types of faults include signal loss, signal error, and message failure.

[0113] (2) Automatic return mode: When the steering system is damaged, the hydraulic cylinder oil return port 2003a / b is immediately opened, and the hydraulic oil in the hydraulic cylinder 20a / b can be directly returned to the oil tank 36a / b from the hydraulic cylinder oil return port 2003a / b, so that the piston rod of the hydraulic cylinder 20a / b can automatically return to the neutral position.

[0114] Damage to the steering system includes circuit breakage, rupture of the hydraulic pipe 310, and the like.

[0115] (3) Steering system self-recovery mode: when the steering system fails, the steering system adopts the emergency centering mode of the (1) item, and real-time monitoring is performed. If the ECU controller 31a / b receives no error signal again, the steering system failure is removed, the steering system automatically recovers to the normal steering mode, and mode judgment is performed.

[0116] (4) Servo motor 32a / b self-recovery mode: when the temperature of the servo motor 32a / b is too high and exceeds the set early warning temperature value, the servo motor 32a / b sends an alarm to the ECU controller 31a / b, the ECU controller 31a / b sends a control signal to the servo motor 32a / b, linear flow reduction is performed, and when the temperature of the servo motor 32a / b is reduced to the normal range, the servo motor 32a / b can work normally. When the voltage of the servo motor 32a / b is too high and exceeds the set maximum temperature voltage and lasts for 200 ms, the servo motor 32a / b sends an alarm to the ECU controller 31a / b, the ECU controller 31a / b sends a voltage signal to make the servo motor 32a / b stop, and the servo motor 32a / b can work normally under normal voltage.

[0117] (5) Steering error automatic correction mode: after the vehicle is turned off, the steering wheel is automatically returned to about 100°, and there is a rotation of the front axle. At this time, because of the power-off after the vehicle is turned off, the rear wheel does not rotate, and there is an error between the target value and the control value of the rear wheel. The steering system is powered on, the rear wheel needs to automatically follow, and the difference caused by the automatic rotation of the steering wheel is compensated. At this time, the maximum speed limit of the rear wheel is 3° / s.

[0118] For those skilled in the art, according to the teachings of the present application, the changes, modifications, replacements and variations made to the embodiments without departing from the principles and spirits of the present application still fall within the protection scope of the present application.

Claims

1. A steering hydraulic system for a multi-axle vehicle, comprising a vehicle frame, a front axle, a rear axle, an engine, and a steering wheel, wherein front wheels are provided at both ends of the front axle and rear wheels are provided at both ends of the rear axle, and wherein: It also includes a control mechanism and an actuator, the actuator includes a hydraulic cylinder, the hydraulic cylinder is provided on the rear axle, the control mechanism is provided on the vehicle frame or the rear axle, the control mechanism is used to receive engine speed information, steering wheel angle information, front wheel angle information, rear wheel angle information, vehicle speed information, displacement information of the hydraulic cylinder piston rod, and control the extension and retraction of the hydraulic cylinder; The control mechanism adopts a first control mechanism, which includes an ECU controller, a servo motor, a gear pump, an oil tank, a one-way valve, a control valve, a hydraulic pipe fitting, and a sensor; The ECU controller is used to receive engine speed information, steering wheel angle information, front wheel angle information, rear wheel angle information, vehicle speed information, displacement information of the hydraulic cylinder piston rod, and control the operation of the servo motor; The servo motor is used to drive the gear pump; The gear pump is used to pump the hydraulic oil in the oil tank; The oil tank is used to store hydraulic oil; The one-way valve is used to control the one-way outflow of hydraulic oil in the oil tank; During the extension and retraction process of the hydraulic cylinder, the control valve is used to control the closure of the hydraulic cylinder return oil port on the hydraulic cylinder. When the hydraulic cylinder maintains the neutral state, the control valve is used to control the opening of the hydraulic cylinder return oil port on the hydraulic cylinder to drain oil. Hydraulic pipe fittings are used to connect oil tanks and hydraulic cylinders, control valves and hydraulic cylinders, control valves and oil tanks; The sensor is used to detect the displacement information of the hydraulic cylinder piston rod and transmit the displacement information of the hydraulic cylinder piston rod to the ECU controller; The hydraulic oil delivered by the gear pump is delivered to the oil inlet of the hydraulic cylinder through hydraulic pipe fittings in one way, and is delivered to the oil outlet of the hydraulic cylinder through hydraulic pipe fittings in the other way. A branch is branched off on the hydraulic pipe fitting delivered to the oil inlet of the hydraulic cylinder and connected to the control valve oil inlet of the first control valve. A branch is branched off on the hydraulic pipe fitting delivered to the oil outlet of the hydraulic cylinder and connected to the control valve oil inlet of the second control valve. The control valve oil outlet of the first control valve and the control valve oil outlet of the second control valve are combined and connected to the oil return port of the oil tank through hydraulic pipe fittings. The control valve oil outlet of the first control valve and the control valve oil outlet of the second control valve are combined and connected to the oil return port of the hydraulic cylinder through hydraulic pipe fittings.

2. A steering hydraulic system for a multi-axle vehicle according to claim 1, characterized in that: The first control mechanism is arranged on the vehicle frame.

3. A steering hydraulic system for a multi-axle vehicle according to claim 2, characterized in that: The first control mechanism also includes a coupling and a connecting disk. The ECU controller is arranged at the end of the servo motor. The output end of the servo motor is connected to the input end of the gear pump through a coupling. The gear pump is connected to the oil tank through a connecting disk. The one-way valve is provided inside the oil tank. The control valve is provided on the coupling. The sensor is provided on the hydraulic cylinder.

4. A steering hydraulic system for a multi-axle vehicle according to claim 3, characterized in that: The sensor is a microelectronic optical sensor, and the hydraulic cylinder is provided with the microelectronic optical sensor.

5. The steering hydraulic system for a multi-axle vehicle according to claim 4, characterized in that: The control mechanism adopts a second control mechanism, which is arranged on the rear axle. The second control mechanism includes the ECU controller, the servo motor, the coupling, the gear pump, the connecting plate, the oil tank, the one-way valve, the control valve, the sensor, and an integrated valve block. The integrated valve block replaces the hydraulic pipe fittings. The coupling, gear pump, connecting plate, and control valve are all arranged in the integrated valve block, and the integrated valve block is connected to the hydraulic cylinder.

6. A control method for a steering hydraulic system of a multi-axle vehicle according to any one of claims 1 to 5, characterized in that: The method comprises the following steps: the control mechanism calculates and determines whether the absolute value of the front wheel turning angle is less than or equal to 3°; when the absolute value of the front wheel turning angle is less than or equal to 3°, the control mechanism controls the hydraulic cylinder to maintain a neutral state so that the rear wheels go straight without turning; When the absolute value of the front wheel steering angle is greater than 3°, the control mechanism determines whether the vehicle speed is less than 45 km / h and whether the rear wheel steering angular velocity is less than or equal to 8° / s. When the vehicle speed is greater than or equal to 45 km / h or the rear wheel steering angular velocity is greater than or equal to 8° / s, the control mechanism controls the hydraulic cylinder to maintain the neutral state, so that the rear wheels go straight without turning; When the vehicle speed is less than 45 km / h and the rear wheel angular velocity is less than or equal to 8° / s, the control mechanism controls the hydraulic cylinder piston rod to extend so that the rear wheels turn in opposite directions to the front wheels.

7. The control method for a steering hydraulic system of a multi-axle vehicle according to claim 6, characterized in that: When the steering hydraulic system applied to a multi-axle vehicle fails or is damaged, the control mechanism controls the hydraulic cylinder to maintain a neutral state.

8. The control method for a steering hydraulic system of a multi-axle vehicle according to claim 7, characterized in that: When the control mechanism successfully receives the correct signal again, the steering hydraulic system applied to the multi-axle vehicle is freed from fault and the steering hydraulic system applied to the multi-axle vehicle operates normally.

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