CN107284521A - The control method of the electro-hydraulic steering of vehicle multi-mode formula - Google Patents

Abstract

The invention discloses a control method for multi-mode electro-hydraulic steering of a vehicle. The method includes: step 1, obtaining the set steering mode; step 2, judging whether the steering mode is the rear axle lock mode; if yes, then performing step 3; otherwise Execute step 4; step 3, control the centering and locking of the rear steering axle, and return to step 1; step 4, detect the state of the rear steering axle; step 5, judge whether the rear steering axle is centering and locking: if yes, go to step 6; otherwise, go to step 7; step 6, when it is detected that the front steering axle produces a steering action and the rotation angle of the front steering axle is within the first preset range for the first time, the rear steering axle is unlocked and follows the steering of the front steering axle, and returns to step 1; Step 7, the rear steering axle follows the steering of the front steering axle, and returns to step 1. The invention can effectively improve the adaptability of the multi-axle vehicle to different working conditions, the turning safety and handling stability in the high-speed state, and simultaneously take into account the passability in the low-speed state.

Description

Control method for vehicle multi-mode electro-hydraulic steering

technical field

The invention relates to the technical field of special vehicle chassis, and more specifically, the invention relates to a control method for multi-mode electro-hydraulic steering of a vehicle.

Background technique

The multi-axle heavy-duty special vehicle chassis has the characteristics of long body, large tonnage, and many axles. The steering performance of the chassis directly affects the handling stability, active safety and economical use of the vehicle; at the same time, special vehicles are required under complex off-road driving conditions. The chassis should have high maneuverability and smoothness. Therefore, heavy-duty vehicle chassis generally adopt multi-axis steering technology.

However, the traditional mechanical transmission hydraulic power-assisted multi-axis steering system mechanically connects the steering rods of the front and rear axle groups through connecting rods, and arranges hydraulic power cylinders on each axle to achieve steering assistance. Due to the long wheelbase of the multi-axis chassis, Usually there are problems such as difficulty in rod arrangement and large flexibility. The steering system using hydrostatic transmission between the front axle and the rear axle group can effectively improve the driving stability of the vehicle, but the hydraulic system of the hydrostatic transmission is complicated and difficult to change, and it still cannot fully adapt to the current use of the steering system. need.

Therefore, how to improve the driving safety and handling stability under the premise of ensuring the driving stability of the multi-axle heavy-duty special vehicle has become a technical problem to be solved urgently and the focus of research by those skilled in the art.

Contents of the invention

In order to solve the problems existing in the existing steering method of mechanical transmission and hydraulic power assistance, such as the difficulty in the arrangement of the rod system and the relatively large flexibility, the present invention innovatively provides a control method for the multi-mode electro-hydraulic steering of vehicles, which provides a new solution for the steering of multi-axle vehicles. An effective solution, which has completely broken through the traditional mechanical transmission hydraulic power-assisted multi-axis steering control scheme. The invention is developed based on the compact structure and multi-mode steering requirements of multi-axle vehicles, so as to make up for the shortcomings of traditional steering technology and effectively improve multi-axle vehicles. The steering characteristics of the vehicle can effectively provide the passability of the vehicle at low speeds and the stability of high-speed driving, and at the same time effectively improve the handling stability of the vehicle.

In order to achieve the above technical purpose, the present invention discloses a control method for multi-mode electro-hydraulic steering of a vehicle. The control method includes the following steps:

Step 1. Obtain the currently set steering mode when the vehicle is powered on;

Step 2, judging whether the current steering mode is the rear axle lock mode: if yes, go to step 3; if not, go to step 4;

Step 3, control the rear steering axle to be in the centering lock state, return to step 1;

Step 4, detecting the state of the rear steering axle;

Step 5, judging whether the current state of the rear steering axle is the centering lock state: if yes, then execute step 6 while the engine is on; if not, then execute step 7 when the engine is on;

Step 6, when it is detected that the front steering axle produces a steering action and the rotation angle of the front steering axle is within the first preset range for the first time, the rear steering axle is unlocked and follows the steering of the front steering axle, and returns to step 1;

Step 7, the rear steering axle follows the steering of the front steering axle, and returns to step 1.

Based on the above-mentioned multi-mode electro-hydraulic steering control method, the present invention has high rationality and safety, has outstanding advantages such as rigorous control logic, strong versatility, and is suitable for multi-axis electronically controlled hydraulic power steering systems. Handling stability and driving safety of high-speed vehicles, while taking into account the passability requirements of low-speed turns. In addition, the control strategy of the multi-mode electro-hydraulic steering system of the present invention is highly versatile, and it is designed on the basis of the target vehicle type. Under the technical inspiration of the present invention, it can be applied to other various vehicle types with only minor changes.

When the rear axle of the present invention is unlocked, the unlocking action can only be completed when the front axle rotation angle reaches within the first preset range. This design makes the rear steering axle unable to unlock when the current steering axle rotation angle is greater than the first preset range, avoiding this The reverse steering of the rear steering axle follows, in line with the driving characteristics and habits of the vehicle.

Further, in step 1, the steering mode includes a road steering mode;

In step 6 or step 7, when the rear steering axle follows the steering of the front steering axle in the highway steering mode, the rotation angle of the rear steering axle is related to the rotation angle of the front steering axle and the real-time vehicle speed: when the vehicle speed is less than the first threshold, the rotation angle of the rear steering axle is related to the front The steering axle angle is the same; when the vehicle speed is greater than or equal to the first threshold and less than the second threshold, under the same front steering axle angle, the rear steering axle angle decreases with the increase of vehicle speed; when the vehicle speed is greater than or equal to the second threshold And when it is less than or equal to the third threshold, the steering angle of the rear steering axle is zero; when the vehicle speed is greater than the third threshold, the electromagnetic reversing valve driving the rear steering axle is powered off, and the rear steering axle is controlled to be in a centering lock state.

In the highway steering mode, the steering angle of the rear steering axle gradually decreases with the increase of the vehicle speed until it is aligned and locked at high speed, which ensures the stability and safety of the vehicle at high speed, avoids tail flicking and other phenomena, and improves the driver's awareness of the vehicle. manipulation. When the electromagnetic reversing valve of the steering axle is powered off after being driven by the present invention, the YA3 electromagnetic reversing valve and the YA4 electromagnetic reversing valve are powered off, so that the four-axle power-assisted centering cylinder is centered and locked and the five-bridge power-assisted centering cylinder is centered and locked , To ensure that the solenoid valve is accidentally powered off or lost, the rear axle can be immediately centered and locked to avoid steering out of control, improve safety, and prevent the occurrence of danger. Moreover, in the road steering mode, the design of the relationship between the power supply or power-off status of YA3 and YA4 and the speed of the vehicle avoids frequent lock-up power supply and power-off operations when the vehicle speed fluctuates, which can greatly improve the service life of components. .

Further, in step 1, the steering mode also includes a field steering mode;

In step 6 or step 7, when the rear steering axle follows the steering of the front steering axle in the field steering mode, the vehicle speed at this time is less than or equal to the fourth threshold, and the rotation angle of the rear steering axle is related to the rotation angle of the front steering axle, wherein the fourth threshold is less than first threshold. The field steering mode is designed to meet the needs of the vehicle to obtain the minimum turning radius when passing through a narrow field. At this time, the rear axle has a large turning angle, so this mode is only suitable for low-speed driving. The invention innovatively designs three steering modes, which can realize the needs of the vehicle in different working conditions. Under various driving conditions, the driver can conveniently select the steering mode that best meets the current road conditions, so that the overall performance of the vehicle can reach optimal.

Further, in step 6 or step 7, in the field steering mode, if the vehicle speed is always greater than the fourth threshold within the first duration, the field steering mode is automatically switched to the road steering mode, and the rear steering axle angle is changed at a constant rate during the switching process. Smooth transition.

In the present invention, when the field steering mode is used for driving, the system automatically switches to the road steering mode after the vehicle speed clock is greater than the fourth threshold and lasts for a first period of time, so as to ensure the steering stability during high-speed driving and avoid tail flicking, sharp turns, Occurrence of adverse working conditions such as rollover.

Further, in step 6 or step 7, when the current steering mode is the road steering mode automatically switched through the field steering mode, if the vehicle speed is always less than the fifth threshold and the front steering axle angle is in the second preset range within the second time period , the road steering mode is automatically switched to the field steering mode, and the rear steering axle angle transitions smoothly at a constant rate during the switching process; wherein, the fifth threshold is smaller than the fourth threshold.

Further, in step 6 or step 7, in the road steering mode or field steering mode, if the front steering axle rotation angle is within the third preset range, the rear steering axle rotation angle is set to zero. The corner within the third preset range is the corner dead zone of the rear steering axle. The design of the dead zone of the corner of the rear axle can avoid the response of the rear steering axle caused by small disturbance input and improve the stability and safety of the vehicle when driving at high speed. Especially when driving at high speed, avoid excessive steering sensitivity of the rear axle.

Further, in step 6 or step 7, in the highway steering mode, if the front steering axle angle is outside the third preset range, the rear steering axle angle is calculated in the following manner: Step S1, determine the rear steering axle angle according to the front steering axle angle The basic target angle of rotation; step S2, determine the angle percentage according to the current vehicle speed; step S3, determine the rear steering axle angle by using the basic target angle of rotation and the angle percentage.

Further, in the process of controlling the steering of the vehicle, when the switching conditions between the modes are met, the manually selected steering mode will automatically take effect;

Manually turn on or off the rear axle lock mode through the rear axle lock rocker switch with the highest priority; manually switch road steering mode to rear axle lock mode, manually switch field steering mode to rear axle lock mode, manually switch rear axle The lock-up mode to the road steering mode need to meet the same effective conditions: the vehicle speed is less than the fifth threshold and the front steering axle angle is within the second preset range;

Manually select the road steering mode or the field steering mode through the human-computer interaction interface; when manually switching the road steering mode to the field steering mode, if the vehicle speed is less than the fifth threshold and the front steering axle angle is within the second preset range, the manual switching will take effect; When manually switching the field steering mode to the highway steering mode, if the vehicle speed is lower than the fifth threshold, the manual switching will take effect.

When the driver performs the steering mode switching operation, if the steering mode switching conditions are not met at that time, the steering mode switching cannot be performed immediately, and the switching action can only be completed after the conditions are met, which ensures the stability and safety of the steering mode switching. Avoid the sudden state change of the rear axle, improve the smoothness of switching and the seamless connection of corners in different modes.

Through the settings of the rear axle locking rocker switch and HMI in the cab, the driver can conveniently operate and monitor the status of the steering system, improve the sense of driving control, and meet the design concept of ergonomics. More specifically, the rear axle lock rocker switch has the highest priority, and its default state is the rear axle lock mode, which improves the safety and handling stability of the vehicle and avoids adverse phenomena such as rear axle flicking; through the HMI, it can Switch between highway steering mode and field steering mode, check current steering mode, check steering parameter information, check steering alarm information, check historical faults, and debug steering system to meet the requirements of drivers and related operators on the steering system. Omnidirectional monitoring and management make the present invention have outstanding advantages such as convenience and simplicity.

Further, the first preset range is -3°～﹢3°, the second preset range is -3°～﹢3°, and the third preset range is -3°～﹢3° , the first threshold is 30km/h, the second threshold is 45km/h, the third threshold is 50km/h, the fourth threshold is 15km/h, and the fifth threshold is 5km/h , the first duration is 3s, and the second duration is 3s.

The invention adopts a reasonable control method and control parameters, effectively guarantees the control accuracy and response speed of the rear axle, and satisfies the reasonable control under various error conditions.

Further, the vehicle is a five-axle special vehicle with five steering axles, wherein the first and second axles are front steering axles with synchronous mechanical control hydraulic steering, the third axle is a non-steering axle, and the fourth and fifth axles are rear axles. Steering bridge and independent electronically controlled hydraulic steering; during the steering process, the turning angle of the fourth axle is smaller than that of the fifth axle.

The beneficial effects of the present invention are: the present invention can effectively improve the adaptability of multi-axle vehicles to different working conditions, the driving safety and handling stability when turning at high speeds, and at the same time take into account the requirements for passability at low speeds, and meet the Basic driving habits of conventional vehicles.

Description of drawings

FIG. 1 is a schematic flowchart of a control method for multi-mode electro-hydraulic steering of a vehicle according to the present invention.

Fig. 2 is a system block diagram for implementing the control method of the vehicle multi-mode electro-hydraulic steering of the present invention.

Figure 3 is a graph of the basic target rotation angle.

Fig. 4 is a curve diagram of the control steering angle target value in the highway steering mode.

detailed description

The control method of the vehicle multi-mode electro-hydraulic steering according to the present invention will be explained and described in detail below in conjunction with the accompanying drawings.

As shown in Figures 1 and 2, the present invention discloses a control method for multi-mode electro-hydraulic steering of a vehicle. This embodiment takes a five-axis special vehicle as an example to design a multi-mode electro-hydraulic steering control strategy, which has five Steering bridges, wherein the first and second axles are front steering axles with synchronous mechanical control of hydraulic steering, and the third axle is a non-steering bridge. The electronically controlled hydraulic power steering scheme, the present invention serves as the four-bridge and five-bridge independent electronically controlled hydraulic steering of the rear steering bridge, making the steering action of the vehicle more flexible and coordinated, and meeting the corner requirements of various steering modes; in this embodiment, the A dual-channel angle sensor is arranged at the left wheel of the above-mentioned first, fourth and fifth bridges to monitor the rotation angle of each wheel. By installing the dual-channel angle sensor, redundant detection of the rotation angle can be performed. When the dual-channel angle When the sensor is working normally, the average value of the two output signals is taken as the final measurement value of the angle signal, and at the same time, the mutual judgment is made by comparing the two signals to improve safety and reliability. In order to improve steering safety and stability, in the steering process realized by the present invention, the turning angle of the front four-axle is smaller than the turning angle of the rear five-axle, thereby effectively improving the steering stability, reliability and safety. In addition, the present invention carries out all-round three-dimensional monitoring and output of the steering system by setting relevant sensors and buzzers, and simultaneously extracts information such as vehicle speed and engine speed, and completes comprehensive control of the steering system in combination with other relevant parameters. In this embodiment, the electro-hydraulic steering input and input signal are as follows.

The control method of the multi-mode electro-hydraulic steering of the vehicle includes the following steps:

Step 1. Obtain the currently set steering mode when the vehicle is powered on; in the present invention, the steering mode includes rear axle lock mode, highway steering mode and field steering mode.

It should be noted that the present invention realizes the driver to operate the three modes by setting the rear axle locking rocker switch and the human-machine interface (HMI) inside the cab, such as the switching operation between the three modes, but only the The switching action of the steering mode can only be performed when the switching condition is met. Among them, the default position of the rear axle lock rocker switch is the rear axle lock mode. When passing through a complex road surface, you can choose the rear axle lock mode open position to be the rear axle steerable state, and the rear axle steerable state includes road steering mode and field steering mode, the default is highway steering mode. In the Human-Machine Interface (HMI), the road steering mode and field steering mode can be selected or switched. In this embodiment, the human-machine interaction interface (HMI) may include a system main interface, a steering parameter interface, a steering debugging interface, and a historical fault query interface. For the Human-Machine Interface (HMI), when the switching conditions between the road steering mode and the field steering mode are not met, the HMI mode selection button is gray and unavailable to avoid human misoperation; when the switching conditions are met, the HMI mode selection button The button is highlighted and can be operated. The HMI mode selection button is unavailable and the design of the highlight can remind the driver more intuitively and clearly, avoid unnecessary redundant operations, and simplify driving difficulty. When the vehicle is powered on and the engine is stopped, the selection and switching of the steering mode is not subject to the above switching conditions.

Step 2, judging whether the current steering mode is the rear axle lock mode: if yes, go to step 3; if not, go to step 4.

Step 3, control the rear steering axle to be in the centering lock state, return to step 1.

Step 4, detecting the status of the rear steering axle.

Step 5, judging whether the current state of the rear steering axle is centered and locked: if yes, execute step 6; if not, execute step 7.

Step 6, when it is detected that the front steering axle produces a steering action and the rotation angle of the front steering axle is within the first preset range for the first time, the rear steering axle is unlocked, followed by the steering of the front steering axle, and then returns to step 1. Specifically, as shown in Figure 3 and Figure 4, if the current mode is road steering mode, when the rear steering axle follows the front steering axle in road steering mode, the angle of the rear steering axle is also related to the angle of the front steering axle and the real-time vehicle speed: When the vehicle speed is less than the first threshold, the angle of the rear steering axle is the same as that of the front steering axle; increase and decrease; when the vehicle speed is greater than or equal to the second threshold and less than or equal to the third threshold, the rear steering axle is fully returned to the center, so that the rear steering axle angle is zero; when the vehicle speed is greater than the third threshold, the rear steering axle is driven The electromagnetic reversing valves YA3 and YA4 are always in the power-off state, and the rear steering axle is in the centering lock state after control. If the current mode is the field steering mode, when the rear steering axle follows the front steering axle in the field steering mode, the vehicle speed is less than or equal to the fourth threshold, and the rotation angle of the rear steering axle is related to the rotation angle of the front steering axle, where the fourth threshold is smaller than the first a threshold. In the road steering mode or field steering mode, the present invention innovatively sets the dead zone of corners: if the corner angle of the front steering axle is within the third preset range, the corner angle of the rear steering axle is set to zero. In addition, in the road steering mode, if the front steering axle angle is outside the third preset range, the rear steering axle angle is calculated as follows:

Step S1, determining the basic target steering angle of the rear steering axle according to the steering angle of the front steering axle;

Step S2, determine the percentage of rotation angle according to the current vehicle speed; for the vehicle speed, the present invention collects two road speed signals through different channels, as a redundant design, for example, when the two road speed signals work normally, take the average value of the two road output signals as the vehicle speed The final measurement of the signal.

Step S3, using the basic target steering angle and the steering angle percentage to determine the steering angle of the rear steering axle.

In the field steering mode, if the vehicle speed is always greater than the fourth threshold within the first period of time, the field steering mode is automatically switched to the road steering mode, and the rear steering axle angle is smoothly transitioned at a constant rate during the switching process. When the current steering mode is the road steering mode automatically switched by the field steering mode, if the vehicle speed is always less than the fifth threshold and the front steering axle angle is within the second preset range within the second time period, the road steering mode is automatically switched to the field Steering mode, and the steering angle of the rear steering axle transitions smoothly at a constant rate during the switching process; wherein, the fifth threshold is smaller than the fourth threshold. In the process of controlling the steering of the vehicle, when the switching conditions between the modes are met, the manually selected steering mode will automatically take effect; the rear axle lock mode can be manually turned on or off through the rear axle lock rocker switch with the highest priority; the road steering can be switched manually Mode to rear axle lock mode, manual switch from field steering mode to rear axle lock mode, manual switch from rear axle lock mode to highway steering mode must meet the same valid conditions: the vehicle speed is less than the fifth threshold and the front steering axle angle is at the first 2. Within the preset range; manually select the road steering mode or the field steering mode through the man-machine interface; when manually switching the road steering mode to the field steering mode, if the vehicle speed is less than the fifth threshold and the front steering axle angle is within the second preset range , the manual switch takes effect; when manually switching the field steering mode to the highway steering mode, if the vehicle speed is less than the fifth threshold, the manual switch takes effect.

Step 7, the rear steering axle follows the steering of the front steering axle, and returns to step 1. Specifically, as shown in Figure 3 and Figure 4, if the current mode is road steering mode, when the rear steering axle follows the front steering axle in road steering mode, the angle of the rear steering axle is also related to the angle of the front steering axle and the real-time vehicle speed: When the vehicle speed is less than the first threshold, the angle of the rear steering axle is the same as that of the front steering axle; increase and decrease; when the vehicle speed is greater than or equal to the second threshold and less than or equal to the third threshold, the rear steering axle angle is zero; when the vehicle speed is greater than the third threshold, the electromagnetic reversing valve driving the rear steering axle is powered off , After controlling, the steering axle is in the centering lock state. If the current mode is the field steering mode, when the rear steering axle follows the front steering axle in the field steering mode, the vehicle speed is less than or equal to the fourth threshold, and the rotation angle of the rear steering axle is related to the rotation angle of the front steering axle, where the fourth threshold is smaller than the first a threshold. In the highway steering mode or the field steering mode, if the front steering axle rotation angle is within the third preset range, the rear steering axle rotation angle is zero. In addition, in the road steering mode, if the front steering axle angle is outside the third preset range, the rear steering axle angle is calculated as follows:

In step S1, the basic target angle of the rear steering axle is determined according to the angle of the front steering axle; in this embodiment, the basic target angles of the fourth and fifth axles are calculated according to the angle output value of the first axle, as shown in FIG. 3 .

Step S2, determine the percentage of rotation angle according to the current vehicle speed, as shown in FIG. 4 .

Step S3, using the basic target rotation angle and the rotation angle percentage to determine the steering angle of the rear steering axle. In this embodiment, the product of the basic target rotation angle and the rotation angle percentage is the rotation angle of the fourth and fifth axles, that is, the control target value.

In the field steering mode, if the vehicle speed is always greater than the fourth threshold within the first period of time, the field steering mode is automatically switched to the road steering mode, and the rear steering axle angle is smoothly transitioned at a constant rate during the switching process. When the current steering mode is the road steering mode automatically switched by the field steering mode, if the vehicle speed is always less than the fifth threshold and the front steering axle angle is within the second preset range within the second time period, the road steering mode is automatically switched to the field Steering mode, and the steering angle of the rear steering axle transitions smoothly at a constant rate during the switching process; wherein, the fifth threshold is smaller than the fourth threshold. In the process of controlling the steering of the vehicle, when the switching conditions between the modes are met, the manually selected steering mode will automatically take effect; the rear axle lock mode can be manually turned on or off through the rear axle lock rocker switch with the highest priority; the road steering can be switched manually Mode to rear axle lock mode, manual switch from field steering mode to rear axle lock mode, manual switch from rear axle lock mode to highway steering mode must meet the same valid conditions: the vehicle speed is less than the fifth threshold and the front steering axle angle is at the first 2. Within the preset range; manually select the road steering mode or the field steering mode through the man-machine interface; when manually switching the road steering mode to the field steering mode, if the vehicle speed is less than the fifth threshold and the front steering axle angle is within the second preset range , the manual switch takes effect; when manually switching the field steering mode to the highway steering mode, if the vehicle speed is less than the fifth threshold, the manual switch takes effect.

In this embodiment, the parameters involved above are specifically as follows: the first preset range is -3°～﹢3°, the second preset range is -3°～﹢3°, and the third preset range is -3°～ ﹢3°, the first threshold is 30km/h, the second threshold is 45km/h, the third threshold is 50km/h, the fourth threshold is 15km/h, the fifth threshold is 5km/h, the first duration is 3s, The second duration is 3s. For example, for the road steering mode, when the vehicle speed is increased, when the vehicle speed reaches 30km/h, under the same steering angle of the first axle, as the vehicle speed continues to increase, the rear axle rotation angle gradually decreases; until the vehicle speed reaches 45km/h After h, the rear axle will return to normal; when the vehicle decelerates, when the vehicle speed is higher than 50km/h, YA3 and YA4 are always in the power-off state; when the vehicle speed is higher than 45km/h and lower than 50km/h, YA3, YA4 YA4 remains in the original state; when the vehicle speed is lower than 45km/h, if the rear axle is locked, YA3 and YA4 are in the power-off state; if the rear axle is in the unlocked state, YA3 and YA4 are in the power-on state . For another example, for the field steering mode, the field steering mode is only valid when the vehicle speed is lower than 15km/h; when the vehicle speed exceeds 15km/h and lasts for 3s, the field steering mode will automatically switch to the highway steering mode, and the corner Smooth transitions at a constant rate. After the vehicle steering mode is automatically switched to the road steering mode due to overspeeding in the field steering mode, when the vehicle speed returns below 5km/h and the first axle turning angle is within ±3° for 3s, the vehicle steering mode is switched back to the field steering mode, and the Corners transition smoothly at a constant rate during the process.

As shown in Figure 3, set the dead zone angle of the wheel to be ±3°. After the dead zone angle is exceeded, the rear steering axle angle quickly follows. The Ackermann principle performs cornering for steering. Let the left wheel rotation angle of the first bridge be α, and the left wheel rotation angle of the fourth or fifth bridge be θ, as follows:

1. Four bridges (highway steering mode)

When -3≤α≤3

θ = 0

When -10<α<-3

When 3<α<10

When -27.4≤α≤-10 and 10≤α≤31

When α＜-27.4

θ=7.6

When α>31

θ=-8.8

2. Five bridges (highway steering mode)

When -3≤α≤3

θ = 0

When -10<α<-3

When 3<α<10

When -27.4≤α≤-10 and 10≤α≤31

When α＜-27.4

θ = 16.8

When α>31

θ=-19.2

3. Four Bridges (Site Steering Mode)

When -3≤α≤3

θ = 0

When -10<α<-3

When 3<α<10

When -27.4≤α≤-10 and 10≤α≤31

When α＜-27.4

θ = 13.2

When α>31

θ=-15.2

4. Five bridges (field steering mode)

When -3≤α≤3

θ = 0

When -10<α<-3

When 3<α<10

When -27.4≤α≤-10 and 10≤α≤31

When α＜-27.4

θ = 23.2

When α>31

θ=-26.5

When the engine is running, the steering mode switching conditions are shown in the table below, and the mode switching can only be completed when the steering mode switching conditions are met. When the driver performs the steering mode switching operation, but the vehicle state does not meet the steering mode switching conditions, the control system will automatically complete the steering mode switching action after the steering mode switching conditions are met.

In addition, the present invention detects and judges each signal in real time. When a failure occurs, relevant actions and alarms are executed to ensure reliability and safety during driving; specifically, when the main pump of the electro-hydraulic steering system of the rear axle fails, The emergency pump can immediately output power to the hydraulic system. At this time, in order to avoid heat generation and other problems caused by the long-term operation of the emergency pump, it is judged that when the first bridge rotation angle is within ±3° and maintained for more than 3s, align the fourth and fifth bridges with the electromagnetic reversing valve (YA3 electromagnetic reversing valve and YA4 electromagnetic reversing valve) Reversing valve) is powered off, and after another 3 seconds, the YA2 electromagnetic reversing valve is energized, so that the emergency circuit of the rear axle is unloaded, and the rear axle remains locked in the neutral position without steering action. The steering system designed based on the steering control method of the present invention comprehensively considers the safety issues under various working conditions, and performs relevant actions and alarms for various errors and failures that may occur, ensuring safe driving. Absolute reliability and safety in the process. The main interface of the steering system designed based on the steering control method of the present invention may include the following contents: current steering mode, steering mode selection button, current vehicle speed, "first bridge angle sensor channel 1 fault" alarm, "first bridge angle sensor channel 2 fault "alarm, "abnormal angle sensor of the first bridge" alarm, "fourth bridge angle sensor channel 1 failure" alarm, "fourth bridge angle sensor channel 2 failure" alarm, "fourth bridge angle sensor abnormality" alarm, "fifth bridge angle sensor channel 1 failure" alarm, Fault" alarm, "Fifth Bridge Angle Sensor Channel 2 Failure" alarm, "Fifth Bridge Angle Sensor Abnormality" alarm, "Vehicle Speed Signal Failure" alarm, "Fourth Bridge Angle Out of Tolerance" alarm, "Fifth Bridge Angle Out of Tolerance" alarm, " "Emergency stop recommended" prompt, "fourth axle alignment failure" alarm, "fifth axle alignment failure" alarm, "site steering mode overspeed, switched to road steering mode" prompt, "rear axle working pressure too low" alarm, " Rear axle main pump failure" alarm, "rear axle emergency oil source has been unloaded" prompt, "steering mode cannot be switched temporarily" prompt, "steering angle is too large" alarm, "fourth axle exceeds the maximum turning angle" alarm, "fifth axle Exceeding the maximum steering angle" alarm, "Not in the rear axle lock mode, height adjustment is prohibited" prompt; the steering parameter interface includes the following content: current vehicle speed, angle sensor channel 1 angle of the first axle, angle sensor channel 2 angle of the first axle, real-time information of the first axle Angle, four-bridge angle sensor channel 1 angle, four-bridge angle sensor channel 2 angle, four-bridge real-time angle, five-bridge angle sensor channel 1 angle, five-bridge angle sensor channel 2 angle, five-bridge real-time angle, four-bridge real-time angle error, Real-time angle error of the fifth axle, emergency oil source pressure, oil cylinder pressure of the fourth axle, oil cylinder pressure of the fifth axle, and steering system pressure of the rear axle. Turn to the debugging interface to perform the zeroing operation of the angle sensor; the historical fault query interface records the following content: fault occurrence time, fault content, fault occurrence time, and the data measured by all sensors in 10 sampling periods before and after it. The historical fault codes can only be cleared manually, and the historical data is updated rollingly, with the latest fault information as the top information. From the "steering system main interface", you can enter the "steering parameter interface", "steering debugging interface" and "historical fault query interface" by entering the password. When the manual switch between road steering mode and field steering mode is not satisfied, the steering mode selection button in the "steering system main interface" becomes "disabled" mode (gray, no response when pressed), and the steering mode cannot be selected through the HMI. The electro-hydraulic steering fault handling and prompt information are shown in the table below.

In addition, the terms "first" and "second" are used for descriptive purposes only, and cannot be interpreted as indicating or implying relative importance or implicitly specifying the quantity of indicated technical features. Thus, the features defined as "first" and "second" may explicitly or implicitly include at least one of these features. In the description of the present invention, "plurality" means at least two, such as two, three, etc., unless specifically defined otherwise.

In the description of this specification, descriptions referring to the terms "this embodiment", "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" mean that the embodiments are combined A specific feature, structure, material, or characteristic described by or example is included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the described specific features, structures, materials or characteristics may be combined in any suitable manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine different embodiments or examples and features of different embodiments or examples described in this specification without conflicting with each other.

The above are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and simple improvements made on the essence of the present invention should be included within the protection scope of the present invention. For example, after the present invention is simply modified, it can be commonly used in other types of vehicles.

Claims (10)

1. the control method of the electro-hydraulic steering of vehicle multi-mode formula, it is characterised in that：The control method comprises the following steps,

Step 1, the steering pattern of current setting is obtained under vehicle power-up state；

Step 2, whether judge current steering pattern is back axle lockdown mode：If it is, performing step 3；If it is not, then holding Row step 4；

Step 3, control rear steering bridge is in centering lockup state, return to step 1；

Step 4, the state of rear steering bridge is detected；

Step 5, whether the state for judging current rear steering bridge is centering lockup state：If it is, performing step 6；If It is no, then perform step 7；

Step 6, when the corner for detecting front steering axle generation go to action and front steering axle is in the first preset range first When, rear steering bridge unlocks, follows front steering axle to turn to, return to step 1；

Step 7, rear steering bridge follows front steering axle to turn to, return to step 1.

2. the control method of the electro-hydraulic steering of vehicle multi-mode formula according to claim 1, it is characterised in that：

In step 1, the steering pattern includes highway steering pattern；

In step 6 or step 7, when rear steering bridge follows the front steering axle to turn under highway steering pattern, rear steering bridge corner is simultaneously It is related to front steering axle corner, real-time speed：When speed is less than first threshold, rear steering bridge corner and front steering axle corner phase Together；When speed is more than or equal to first threshold and is less than Second Threshold, in the case of same front steering axle corner, rear steering bridge Corner reduces with the increase of speed；When speed is more than or equal to Second Threshold and is less than or equal to three threshold values, make rear steering Bridge corner is zero；When speed is more than three threshold values, the solenoid directional control valve of driving rear steering bridge is set to power off, control at rear steering bridge In centering lockup state.

3. the control method of the electro-hydraulic steering of vehicle multi-mode formula according to claim 2, it is characterised in that：

In step 1, the steering pattern also includes place steering pattern；

In step 6 or step 7, when rear steering bridge follows the front steering axle to turn under the steering pattern of place, now speed is less than or waited In the 4th threshold value, rear steering bridge corner is related to front steering axle corner, wherein, the 4th threshold value is less than first threshold.

4. the control method of the electro-hydraulic steering of vehicle multi-mode formula according to claim 3, it is characterised in that：Step 6 or step 7 In, under the steering pattern of place, if speed is consistently greater than the 4th threshold value in the first duration, place steering pattern automatically switches To highway steering pattern, and in handoff procedure, rear steering bridge corner is seamlessly transitted with constant rate of speed.

5. the control method of the electro-hydraulic steering of vehicle multi-mode formula according to claim 4, it is characterised in that：Step 6 or step 7 In, when current steering pattern is the highway steering pattern automatically switched by place steering pattern, if in the second duration Speed is consistently less than the 5th threshold value and front steering axle corner is in the second preset range, then highway steering pattern is automatically switched to Place steering pattern, and rear steering bridge corner is seamlessly transitted with constant rate of speed in handoff procedure；Wherein, the 5th threshold value is less than 4th threshold value.

6. the control method of the electro-hydraulic steering of vehicle multi-mode formula according to claim 5, it is characterised in that：Step 6 or step 7 In, under highway steering pattern or place steering pattern, if front steering axle corner is in the 3rd preset range, make rear steering Bridge corner is zero.

7. the control method of the electro-hydraulic steering of vehicle multi-mode formula according to claim 6, it is characterised in that：Step 6 or step 7 In, under highway steering pattern, if front steering axle corner is in outside the 3rd preset range, rear steering is calculated in the following way Bridge corner：

Step S1, the elementary object corner of rear steering bridge is determined according to front steering axle corner；

Step S2, corner percentage is determined according to current vehicle speed；

Step S3, rear steering bridge corner is determined using the elementary object corner and corner percentage.

8. the control method of the electro-hydraulic steering of vehicle multi-mode formula according to any claim in claim 5 to 7, its feature It is：During controlling Vehicular turn, when the switching condition between meeting pattern, the steering pattern manually selected is given birth to automatically Effect；

By the back axle locking rocker switch of highest priority it is manually opened or close back axle lockdown mode；Manual switching highway turns To pattern to back axle lockdown mode, manual switching place steering pattern to back axle lockdown mode, manual switching back axle lockdown mode Identical effective term need to be met to highway steering pattern：Speed is less than the 5th threshold value and front steering axle corner is in second and preset In the range of；

Highway steering pattern or place steering pattern are manually selected by human-computer interaction interface；Manual switching highway steering pattern is extremely During the steering pattern of place, if speed is less than the 5th threshold value and front steering axle corner is in the second preset range, cut manually Change and come into force；During manual switching place steering pattern to highway steering pattern, if speed is less than the 5th threshold value, manual switching life Effect.

9. the control method of the electro-hydraulic steering of vehicle multi-mode formula according to claim 8, it is characterised in that：Described first presets Scope is 3 ° of 3 °~﹢ of ﹣, and second preset range is 3 ° of 3 °~﹢ of ﹣, and the 3rd preset range is 3 ° of 3 °~﹢ of ﹣, described first Threshold value is 30km/h, and the Second Threshold is 45km/h, and the 3rd threshold value is 50km/h, and the 4th threshold value is 15km/h, 5th threshold value is 5km/h, a length of 3s when described first, a length of 3s when described second.

10. the control method of the electro-hydraulic steering of vehicle multi-mode formula according to claim 1 or 9, it is characterised in that：The vehicle For five axle special vehicles, with five steeraxles, wherein, a bridge and two bridges are front steering axle and synchronization mechanism control hydraulic rotation To three bridges are non-steering axle, and four bridges and five bridges are rear steering bridge and independent electric-controlled hydraulic is turned to；In steering procedure, four bridge corners Less than five bridge corners.