CN110282012B - A method for calculating the target position of a rear axle steering hydraulic cylinder and its steering system - Google Patents

Abstract

The invention provides a method for calculating a target position of a rear axle steering hydraulic cylinder and a steering system thereof. According to the invention, by adding an innovative intelligent target displacement function, closed-loop control of steering hydraulic cylinders and steering wheel operation can be accurately realized, and the control is accurate. The system has safe and reliable performance, greatly improves the safety and stability of the system, and has stable and reliable system design.

Description

A method for calculating the target position of a rear axle steering hydraulic cylinder and its steering system

technical field

The patent of the present invention relates to a high-reliability electromechanical-electrical-hydraulic all-wheel steering system suitable for wheeled vehicles, which belongs to the fields of mechanical, hydraulic and motor vehicle applications.

Background technique

Wheeled equipment is an important part of the army's weapon equipment system, and it is an important land mobile platform for the army, navy and air force to realize the development strategy of "global mobility, three-dimensional protection, and multi-dimensional and multi-energy". Vehicle mobility, in a broad sense, refers to the ability to quickly reach space and regions, including tactical mobility, strategic/campaign mobility. For wheeled vehicles, the improvement of mobility is more focused on improving soft ground and random off-road ground. The passing ability, the driving performance in the plateau and the mountain, the air transportability, etc. The essence of the wheeled vehicle steering system is based on the steering radius of the vehicle, which reflects the degree of agreement between the vehicle's driving trajectory and the driver's intention in time and space, and the degree of stability of the vehicle's driving state. Therefore, steering maneuverability is a decisive factor affecting vehicle maneuverability. Through all-wheel steering technology, reducing the low-speed steering radius, enhancing high-speed stability, and providing special steering forms such as oblique driving has become a worldwide solution to improve the mobility of wheeled vehicles. An effective approach to common problems.

(1) Wheeled vehicles, especially multi-axle wheeled vehicles, through the application of the all-wheel steering system can significantly reduce the steering radius of the vehicle at low speed and improve the vehicle's maneuverability. Internationally, the new 8X8 wheeled armored vehicles are generally based on the 1 and 2-axis steering, and the 4-axis steering is added to improve mobility. Some models use 1, 2, 3, and 4-axis steering, which can generally reduce vehicle steering. Radius around 30%. The multi-wheel/all-wheel steering forms are complex and diverse due to factors such as the number of tactical vehicles changing with the mission profile, the number of axles, and the complex layout. Therefore, at the beginning of the system design, the steering system dynamics, vehicle dynamics The forward design method of the joint virtual road test environment verifies the influence of the function of the all-wheel steering system on the vehicle handling stability, so as to preliminarily determine the operating conditions and the overall scheme.

(2) Compared with engineering vehicles, wheeled vehicles have more complex working conditions and harsher environments. The response characteristics and impact resistance of the follow-up steering axle are the common problems affecting the handling stability and safety of vehicles. The all-wheel steering system of military wheeled vehicles mostly adopts the technical scheme of electro-hydraulic system. The system principle, composition and use method are relatively close to the field of engineering vehicles, but the use environment of military vehicles is more severe. In the case of low-speed off-road roads, steering The non-linear load on the axle will increase rapidly. The statistical average value shows that it is usually about three times larger than the load of the steering axle, which will have a great impact on the response of the follow-up steering axle. Therefore, in the all-wheel steering system of military vehicles, Usually, energy storage devices and elastic devices are added to solve the problems of low-speed shock resistance and high-speed elimination of high-frequency oscillation.

(3) In the case of mode switching and system failure, the active return of the follow-up steering axle and the neutral steering stiffness are the key technologies to ensure the reliability of the system. Under complex load conditions, function switching or system failure of the all-wheel steering system, the follow-up steering axle needs to be able to automatically return to alignment and ensure the steering stiffness in the neutral state, otherwise it will directly affect the vehicle's maneuverability and safety. Therefore, The device that can realize the function of maintaining the center position of the follow-up steering axle and actively returning to the front has become the top priority to ensure its reliability and vehicle driving safety.

From the above comparison, the variable vehicle structure, complex application environment, and harsh use conditions of wheeled vehicles have brought great challenges to the reliable application of all-wheel steering technology on wheeled vehicles. The technical architecture of the all-wheel steering system of engineering vehicles cannot meet the requirements of use. Therefore, it can simultaneously have the dynamic response and shock resistance of the follow-up steering axle in complex environments, and the neutral steering stiffness of the follow-up steering axle under nonlinear loads. The all-wheel steering system with the three core capabilities of the follow-up steering axle active return in the state of system failure and vehicle damage will become a highly reliable all-wheel steering system suitable for wheeled vehicles.

Therefore, developing a high-reliability electro-mechanical-hydraulic all-wheel steering system with the functions of passive neutral position return and rigid locking of the steering axle is the most effective way to solve the above technical problems.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is: how to provide a highly reliable electromechanical-electrical-hydraulic all-wheel steering system.

In order to achieve the above object, technical scheme of the present invention is as follows:

A method for calculating the target position of a rear axle steering hydraulic cylinder, characterized in that when the rear axle participates in steering, the controller needs to calculate the rear axle steering hydraulic pressure by reading the signal of the steering wheel angle sensor when the driver turns the steering wheel The target position of the cylinder is controlled by the current control mode to control the spool opening of the three-position four-way proportional valve, and finally the steering hydraulic cylinder can be extended to the absolute target position, and finally the rear axle steering rod system is driven to achieve the same direction and the opposite direction to the front axle. turn.

Preferably, the controller estimates the value of the steering angle of the front axle wheel according to the value collected by the steering wheel angle sensor, combined with the transmission ratio of the hydraulic steering gear of the front axle and the angular transmission ratio of the steering rod system of the front axle, and then according to the same direction or reverse mode Combine the corresponding co-directional coefficient and reverse coefficient to determine the value of the wheel steering angle of the rear axle, and then combine with the angular transmission ratio of the rear axle steering rod system to obtain the target rotation angle of the left swing arm, and install the rear axle steering hydraulic cylinder through the left swing arm. The arm length is calculated to obtain the piston telescopic target displacement value of the rear axle steering hydraulic cylinder.

Preferably, its control method is as follows:

Among them: θ _sw is the steering wheel angle (°), which is the value collected by the angle sensor, and the range is -900°～900°;

L is the wheelbase of the vehicle (mm), which belongs to the overall layout parameter of the vehicle, ranging from 2800 to 3200;

L _g is the piston telescopic target displacement value of the rear axle steering hydraulic cylinder; the output value is calculated for the system;

L _gg is the distance from the center hole of the left swing arm in the steering rod system of the rear axle to the axis of the ball stud for installing the steering hydraulic cylinder of the rear axle (mm), in the range (180～280);

i _f is the angular transmission ratio of the steering rod system of the front axle, ranging from 0.8 to 1.3;

i _R is the angular transmission ratio of the rear axle steering rod system, ranging from 0.8 to 1.3;

i _T is the steering coefficient of the front and rear axles in the same direction, ranging from 0.2 to 0.8;

i _q is the transmission ratio of the hydraulic power steering gear, which is a constant;

λ is the equivalent wheelbase coefficient of the front axle from the instantaneous center of steering.

A 4X4 electro-hydraulic all-wheel steering system, characterized by comprising a rear axle steering hydraulic cylinder (6), the rear axle steering hydraulic cylinder (6) comprising a cylinder barrel (88), a piston rod (87), a ball stud (36), a clamp (90), an oil cylinder displacement sensor (35), which has a first interface (34) and a second interface (33) respectively connected to the third interface (3) of the rear axle steering integrated valve group (8) through oil pipes 8-P2), the fourth interface (8-T2); the cylinder displacement sensor (35) is installed inside the cylinder; one end of the rear axle steering hydraulic cylinder assembly (6) is connected to the vehicle body attachment through a joint bearing, and the other end is connected to the vehicle body through a joint bearing. The ball head (36) is connected with the left swing arm (70) of the rear axle steering rod system (10), so as to realize the fixing of the rear axle steering hydraulic cylinder assembly (6). The first port (34) of the road is connected with the fifth port (8-A) of the rear axle steering integrated valve group (8), and the second port (33) is connected with the sixth port (8) of the rear axle steering integrated valve group (8). -B) connection, the piston telescopic target displacement value of the rear axle steering hydraulic cylinder adopts the method described above.

The oil outlet of the rear axle steering oil tank assembly is connected with the oil inlet end of the rear axle electric steering pump assembly through an oil pipe, and the oil return port is connected with the oil return port T of the rear axle steering integrated valve group through an oil pipe; the rear axle electric steering The oil outlet of the pump assembly is connected with the oil inlet of the rear axle steering integrated valve group through an oil pipe; the first interface of the rear axle steering hydraulic cylinder assembly is connected with the A port of the rear axle steering integrated valve group through an oil pipe, and the rear axle steering The second port of the hydraulic cylinder assembly is connected with the B port of the rear axle steering integrated valve group through an oil pipe, the rear axle steering hydraulic cylinder assembly is connected with the left swing arm of the rear axle steering rod system, and the steering return locking mechanism assembly is connected. The first port of the unlocking cylinder is connected with the P2 port of the rear axle steering integrated valve group through the oil pipe, and the second port of the unlocking cylinder of the steering return locking mechanism assembly is connected with the T2 port of the rear axle steering integrated valve group through the oil pipe. The return locking mechanism assembly is connected with the right swing arm of the rear axle steering rod system; the rear axle steering integrated valve group is the aforementioned rear axle steering integrated valve group.

Preferably, the first interface is an oil inlet port, which is connected to the oil outlet of the rear axle steering pump assembly, and the second interface is an oil return port that is connected to the oil return port of the rear axle steering oil tank assembly; The four ports are respectively connected with the first port and the second port of the unlocking cylinder of the steering return locking mechanism assembly; the fifth port and the sixth port are connected with the first port and the second port of the rear axle steering hydraulic cylinder assembly.

Preferably, the rear axle steering integrated valve group is fixed on the vehicle body bottom plate through the through hole on the valve body.

Preferably, the steering return locking mechanism assembly is connected with the right swing arm of the steering rod system of the rear axle through a ball stud.

Preferably, the steering wheel and steering gear assembly includes a steering wheel, a combination switch, a first steering transmission shaft, a second steering transmission shaft, a steering wheel angle sensor, an angle transmission case, an intermediate transmission shaft assembly and a hydraulic power steering assembly; the steering wheel and The first steering transmission shaft is connected, and a combination switch bracket is processed in the middle of the first steering transmission shaft for installing the combination switch; the steering wheel angle sensor is installed on the first steering transmission shaft; the first steering transmission shaft is connected with the second steering transmission shaft, One end of the first steering transmission shaft is connected with the steering wheel, the other end is connected with the second steering transmission shaft, the other end of the second steering transmission shaft is connected with the angle transmission case, and one end of the intermediate transmission shaft assembly is matched with the angle transmission case through the universal joint spline. connected, and the other end is connected with the input shaft of the hydraulic power steering gear assembly.

Preferably, the hydraulic power steering gear assembly has two oil circuit interfaces, an oil inlet port P and an oil return port T, which are respectively connected to the oil outlet port of the front axle steering pump and the oil return port of the front axle steering oil tank assembly.

Preferably, the rear axle steering integrated valve group includes a valve body, a three-position four-way proportional reversing valve, two balance valves, four two-position two-way solenoid valves, a two-position three-way solenoid valve and a check valve; the rear axle The steering integrated valve group is fixed on the bottom plate of the vehicle body through the through hole on the valve body, and it has 6 oil circuit ports; the first port is the oil inlet port P connected with the oil outlet port of the rear axle steering pump assembly, the second port is The oil return port T is connected with the oil return port of the rear axle steering oil tank; the third port P2 and the fourth port T2 are respectively connected with the first port and the second port of the unlocking oil cylinder (44) of the steering return locking mechanism assembly. , the fifth port A and the sixth port B are connected to the first port and the second port of the rear axle steering hydraulic cylinder assembly. Unlock the cylinder

Preferably, the rear axle steering hydraulic cylinder includes a cylinder barrel, a piston rod, a ball head, a clamp, and an oil cylinder displacement sensor, which has a first interface and a second interface respectively connected to the fifth interface and the second interface of the rear axle steering integrated valve group through oil pipes. Six ports; the oil cylinder displacement sensor is installed inside the cylinder; one end of the rear axle steering hydraulic cylinder assembly is connected to the vehicle body attachment through a joint bearing, and the other end is connected to the left swing arm of the rear axle steering rod system through a ball The axle steering hydraulic cylinder assembly is fixed, the first port of the upper oil circuit of the rear axle steering hydraulic cylinder assembly is connected to the fifth port of the rear axle steering integrated valve group, and the second port is connected to the sixth port of the rear axle steering integrated valve group .

Preferably, the steering return locking mechanism assembly includes an unlocking oil cylinder, an unlocking spring, a return spring, a mechanical lock assembly, a rotating pin shaft, a return cylinder, a telescopic cylinder, a telescopic shaft, a left support fixing nut, and a left spring support Seat assembly, right spring support assembly, retaining ring between cylinders, pin shaft, unlocking spring support, unlocking cylinder upper bracket, unlocking cylinder lower bracket, ball stud, locking sensor, unlocking sensor, return spring left and right Both ends are loaded into the return cylinder through the left spring support assembly and the right spring support assembly, and the return spring is compressed to the left and right by pushing the left spring support assembly and the right spring support assembly respectively; The shaft runs through the return cylinder and the telescopic cylinder, and can reciprocate and extend relative to the return cylinder and the telescopic cylinder without being locked; Support fixing nut and ball stud assembly; one end of the unlocking cylinder is connected to the upper bracket of the unlocking cylinder by means of a pin and a joint bearing, and the other end is connected to the mechanical lock assembly by means of a pin and a joint bearing; the upper bracket of the unlocking cylinder . The lower bracket of the unlocking cylinder is clamped and fixed in the outer slot of the return cylinder by 4 bolts; the unlocking spring support is fixed on the upper end of the telescopic cylinder by bolts; the device adopts two unlocking springs, one end of the unlocking spring is hung on the mechanical lock assembly On the pin connected to the unlocking cylinder, the other end is hung on the pin of the spring support. The mechanical lock assembly is fixed on the telescopic cylinder through the rotating pins on both sides, and the mechanical lock can rotate up and down around the rotating pins on both sides to complete the unlocking and locking of the telescopic shaft; the retaining ring between the return cylinder and the cylinder block It is connected with the telescopic cylinder through 8 evenly distributed bolts; the unlocking sensor support is fixed on the flange surface of the return cylinder through a threaded connection, the unlocking sensor is fixed on the unlocking sensor support through a threaded connection, and the locking sensor is fixed through a threaded connection on the mechanical lock assembly.

Preferably, the rear axle steering pump assembly includes a motor and a rear axle steering pump, which has an oil inlet and an oil outlet; the oil outlet is connected to the first port P of the rear axle steering integrated valve group through a high-pressure oil pipe; the oil inlet The port is connected with the second port T of the rear axle steering integrated valve group through a low-pressure oil pipe; it is fixed on the vehicle body attachment through bolt connection.

Compared with the prior art, the present invention has the following advantages:

1) A new control relationship has been developed. Through the control relationship of the two working modes of "front and rear axle steering in the same direction" and "reverse steering of front and rear axles", the controller is based on the value collected by the steering wheel angle sensor, combined with the hydraulic steering of the front axle. According to the transmission ratio of the front axle and the angular transmission ratio of the steering rod system of the front axle, the value of the steering angle of the front axle wheel is estimated, and then the value of the steering angle of the rear axle wheel is determined according to the same-direction or reverse mode combined with the corresponding same-direction coefficient and reverse coefficient. , and then combined with the angular transmission ratio of the steering rod system of the rear axle, the target rotation angle of the left swing arm 70 is obtained, and the arm length of the rear axle steering hydraulic cylinder 6 is calculated to obtain the target displacement value of the piston of the rear axle steering hydraulic cylinder 6 through the installation of the left swing arm . By adding an innovative intelligent target displacement function, the closed-loop control of the steering hydraulic cylinder and steering wheel manipulation can be precisely realized, and the control is precise. It has safe and reliable performance, greatly improves the security and stability of the system, and the system design is stable and reliable.

2) Developed a new steering return locking mechanism assembly, which can complete the follow-up expansion and contraction with the rear axle steering hydraulic cylinder when the rear axle is steered normally; when the rear axle is not steering, it can keep the rear axle steering rod tied in the middle Mechanical maintenance and rigid locking of position; when electrical or hydraulic failure occurs in the all-wheel steering system, it can realize passive active return and complete rigid locking, which greatly improves the reliability of the whole set of all-wheel steering device.

3) Developed the rear axle steering integrated valve group structure. The structure and layout of the valve group are reasonable, easy to process, small in space, more reasonable in oil circuit, small in pressure loss, convenient for pipe layout, and convenient for adjustment and operation of each control valve. By adding a three-position four-way proportional valve, the opening of the spool can be precisely controlled, and then the expansion and contraction of the rear axle steering hydraulic cylinder with the target displacement can be precisely controlled to realize the closed-loop control of the steering hydraulic cylinder and steering wheel manipulation.

4) A new electro-mechanical-hydraulic steering system has been developed. The all-wheel steering system of this structure can be conveniently switched between the three modes, and can realize the closed-loop control of the steering hydraulic cylinder and the steering wheel, as well as the passive active return and rigidity of the steering axle. The unlocking and locking control of the locking device has many advantages. In addition, the hydraulic source of the front and rear axles is independent, and the system is safe and reliable.

5) Developed a new all-wheel steering controller assembly. It is convenient to switch between the three modes, considering a variety of failure modes, ensuring the reliable performance of the system under various failure modes. By adding an innovative intelligent target displacement function, the closed-loop control of the steering hydraulic cylinder and steering wheel manipulation can be precisely realized, and the control is precise.

Description of drawings

Fig. 1 Structure diagram of a high reliability electromechanical-electrical-hydraulic all-wheel steering system

Figure 2 Structural diagram of steering wheel and power steering gear assembly

Figure 2-1 Combination switch structure diagram

Figure 2-2 Structure diagram of combination switch bracket

Figure 2-3 Structure diagram of drive shaft assembly 1

Figure 2-4 Front axle steering pump structure diagram

Figure 2-5 Front axle steering oil tank structure diagram

Figure 2-6 Front axle steering oil tank clamp

Figure 3 Front view of the rear axle steering integrated valve group

Figure 4 Structure diagram of the rear axle steering hydraulic cylinder

Figure 4-1 Top view of the rear axle steering hydraulic cylinder

Figure 5 Structural diagram of the rear axle neutral locking mechanism

Figure 5-1 Cross-sectional view of the rear axle neutral locking mechanism

Figure 6 Structural diagram of rear axle steering pump assembly

Figure 6-1 Rear axle steering pump assembly structure Figure 2

Figure 7 Structural diagram of rear axle steering oil tank assembly

Figure 7-1 Front axle steering oil tank clamp diagram

Figure 8 Working principle diagram of hydraulic system

FIG. 9 is a schematic diagram of the equivalent wheelbase coefficient.

The reference numbers are as follows:

Structure diagram of a high-reliability machine-electric-hydraulic all-wheel steering system: 1 Steering wheel and steering gear assembly; 2 Front axle steering oil tank assembly; 3 Front axle steering pump; 4 Rear axle steering oil tank assembly; 5 Front axle steering rod system; 6 rear axle steering hydraulic cylinder assembly; 7 steering return locking mechanism assembly; 8 rear axle steering integrated valve group; 9 all-wheel steering controller assembly; 10 rear axle steering rod system; 11 Rear axle electric steering pump assembly; 70 left swing arm; 71 right swing arm; 72 steering rocker arm;

Structural diagram of steering wheel and power steering gear assembly: 12 steering wheel; 19 first steering transmission shaft; 14 second steering transmission shaft; 13 steering wheel angle sensor; 15 angle transmission box; 16 intermediate transmission shaft assembly; 17 hydraulic power steering gear assembly to make;

Combination switch: 80 left handle, 82 fixing hole, 81 right handle;

Combination switch bracket: 83 threaded through holes, 19 steering shafts;

The overall structure of the steering transmission shaft: 84 combination switch bracket, 85 adjustment mechanism, 86 mounting holes;

Front axle steering pump structure diagram: 301 oil inlet, 302 oil outlet, 303 steering pump mounting hole, 304 steering pump spline shaft;

Front axle steering oil tank structure diagram: 203 steering oil tank; 204 oil tank bracket; 201 oil outlet, 202 oil return port;

Front axle steering oil tank clamp diagram: 205 front axle steering oil tank bracket; 206 clamp;

Front view of the rear axle steering integrated valve group: 24 valve body; 25 three-position four-way proportional reversing valve; 26 two balance valves; four two-position two-way solenoid valves (27, 28, 30, 31); 29 two-position Three-way solenoid valve; 32 check valve; oil ports 8-P, 8-T, 8-P2, 8-T2, 8-A, 8-B;

Rear axle steering hydraulic cylinder structure diagram: 88 cylinder barrel, 87 piston rod, 36 ball head pin, 90 clamp, 89 slot, 35 cylinder displacement sensor, 34 first interface, 33 second interface;

Top view of the rear axle steering hydraulic cylinder: 37 joint bearings;

Rear axle neutral locking mechanism: 44 unlocking cylinder, 52 unlocking spring, 56 return spring, 48 mechanical lock assembly, 60 rotating pin, 45 return cylinder, 49 telescopic cylinder, 40 telescopic shaft, 41 left support fixed Nut, 55 left spring support assembly, 57 right spring support assembly, 47 retaining ring between cylinders, 50 pin, 54 unlocking spring support, 43 unlocking cylinder upper bracket, 42 unlocking cylinder lower bracket, 38 ball head pin, 46 locking sensor, 51 unlocking sensor, 58 unlocking the second interface of the oil cylinder, 59 unlocking the first interface of the oil cylinder;

Rear axle steering pump assembly structure diagram: 110 oil outlet, 112 mounting holes;

Rear axle steering pump assembly structure Figure 2: 111 oil inlet, 112 mounting holes;

Rear axle steering oil tank assembly structure diagram: 403 steering oil tank; 404 oil tank bracket; 401 oil outlet, 402 oil return port;

Front axle steering oil tank clamp diagram: 405 rear axle steering oil tank bracket; 406 clamp;

Detailed ways

The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

In this article, if there are no special instructions, when it comes to formulas, "/" means division, and "×" and "*" mean multiplication.

In order to solve the problems in the prior art, the present invention provides a highly reliable electro-mechanical-hydraulic all-wheel steering system and its rear axle passive self-returning and locking device, especially a 4X4 electro-hydraulic all-wheel steering system. The front axle of the all-wheel steering device of the system adopts the form of hydraulic power-assisted mechanical steering, and the rear axle adopts an electronically controlled hydraulic cylinder to drive the rear axle to steer. Preferably, the high-reliability 4X4 electro-hydraulic all-wheel steering system and its rear axle passive self-aligning and locking device are suitable for wheeled vehicles of more than 5 tons.

The system and its rear axle self-aligning and locking device will be described in detail below with reference to the accompanying drawings.

As shown in Figure 1, the electromechanical all-wheel steering system includes a steering wheel and steering gear assembly 1, a front axle steering oil tank assembly 2, a front axle steering pump 3, a rear axle steering oil tank assembly 4, and a front axle steering Rod system 5, rear axle steering hydraulic cylinder assembly 6, steering return locking mechanism assembly 7, rear axle steering integrated valve group 8, all-wheel steering controller assembly 9, rear axle steering rod system 10, rear axle electric Steering pump assembly 11. The steering wheel and steering gear assembly 1 is connected with the front axle steering rod system 5; the front axle steering pump 3 is installed on the engine, and is driven by the engine to provide a power source to the system, preferably a high-pressure power source; the front axle steering oil tank assembly 2 is out of The oil port 19 is connected with the oil inlet end 22 of the front axle steering pump 3 through an oil pipe, and the oil return port 20 is connected with the oil return port of the power steering gear assembly 17 in the steering wheel and the power steering gear assembly 1 through an oil pipe.

The oil outlet 402 of the rear axle steering oil tank assembly 4 is connected with the oil inlet 111 of the rear axle electric steering pump assembly 11 through an oil pipe, and the oil return port 401 and the oil return port T of the rear axle steering integrated valve group 8 are connected by an oil pipe Connection; the oil outlet 110 of the rear axle electric steering pump assembly 11 is connected with the oil inlet end 8-P of the rear axle steering integrated valve group 8 through the oil pipe; the first interface 34 of the rear axle steering hydraulic cylinder assembly 6 is connected to the rear axle The A port 8-A of the steering integrated valve group 8 is connected through an oil pipe, the second port 33 of the rear axle steering hydraulic cylinder assembly 6 is connected with the B port 8-B of the rear axle steering integrated valve group 8 through an oil pipe, and the rear axle steering The hydraulic cylinder assembly 6 is connected to the left swing arm 70 of the rear axle steering rod system 10, preferably through the ball stud 36; the first interface 59 (oil inlet) of the unlocking cylinder 44 of the steering return locking mechanism assembly 7 It is connected with the P2 port 8-P2 of the rear axle steering integrated valve group 8 through the oil pipe, and the second port 58 (oil outlet) of the unlocking cylinder 44 of the steering return locking mechanism assembly 7 is connected with the rear axle steering integrated valve group 8 T2 The port 8-T2 is connected through an oil pipe, and the steering return locking mechanism assembly 7 is connected with the right swing arm 71 of the rear axle steering rod system 10 , preferably through the ball stud 38 .

Through the above solution, the front and rear axle steering systems are mechanically installed relatively independently, and an independent hydraulic source is used to control the rear axle steering valve group through the all-wheel steering controller 9 to realize three steering modes of the front and rear axles.

Preferably, the steering wheel and steering gear assembly 1 is located in the cockpit of the vehicle, and is fixed to the mounting bracket at the instrument panel in the cockpit through the four oblong holes on the angle adjustment mechanism 20 .

Preferably, the power steering gear assembly 17 in the steering wheel and steering gear assembly 1 is connected with the steering rocker arm 72 of the steering rod system 5 of the front axle through a tapered spline.

Figure 2 shows the steering wheel and steering gear assembly of the present invention. As shown in FIG. 2 , the steering wheel and steering gear assembly 1 includes a steering wheel 12 , a combination switch 18 , a first steering transmission shaft 19 , a second steering transmission shaft 14 , a steering wheel angle sensor 13 , an angle transmission case 15 , and an intermediate transmission shaft assembly 16 and the hydraulic power steering assembly 17. The steering wheel 12 is connected with the first steering transmission shaft 19, and a combination switch bracket is processed in the middle of the first steering transmission shaft 19 for installing the combination switch, preferably the radial installation of the transmission shaft is convenient for connecting the combination switch 18 and the first steering transmission shaft 19 coaxially installed and fixed; the steering wheel angle sensor 13 is installed on the first steering transmission shaft 19 through interference fit; preferably installed under the combined switch bracket of the first steering transmission shaft 19; the first steering transmission shaft 19 and the second steering transmission The shaft 14 is connected, preferably, a spline shaft is processed at the bottom of the first steering transmission shaft 19 to be connected with the second steering transmission shaft 14; one end of the first steering transmission shaft 19 is connected with the steering wheel 12, preferably through a universal joint spline. The other end is connected with the second steering transmission shaft 14, preferably through a universal joint spline; one end of the second steering transmission shaft 14 is connected with the steering transmission shaft assembly 19, preferably through a universal joint spline, and the other end is connected with The angle transmission case 15 is connected, preferably by the universal joint spline; one end of the intermediate transmission shaft assembly 16 is connected with the angle transmission case 15 through the universal joint spline, and the other end is connected with the hydraulic power steering through the universal joint spline. The input shaft of the actuator assembly 17 is connected. In this way, when the driver manipulates the steering wheel 12 , the first steering transmission shaft 19 , the second steering transmission shaft 14 , the steering wheel angle sensor 13 , the angle transmission case 15 and the external spline output end of the hydraulic power steering gear assembly 17 are driven with Coaxial rotation, while the steering wheel angle sensor 14 sends the steering wheel angle signal to the all-wheel steering controller assembly 9.

Preferably, the center of the steering wheel 12 is machined with an inner spline hole, and the top of the first steering transmission shaft 19 is machined with a spline shaft, which is inserted into the inner spline hole in the center of the steering wheel 12 and locked by a nut to complete the steering wheel 11 and the first steering transmission. Connection of shaft 19;

Preferably, four oblong holes are machined on the mechanism 20 for fixing the steering wheel and the power steering assembly 1 on the dashboard.

Preferably, the angle transmission box 15 is installed between the second steering transmission shaft 14 and the power steering gear 17 , the function is to ensure the flexibility of the installation and arrangement of the steering wheel 12 and the power steering gear 17 in the actual vehicle.

The hydraulic power steering gear assembly 17 has two oil circuit interfaces, an oil inlet port P and an oil return port T, which are respectively connected to the oil outlet port 302 of the front axle steering pump 3 and the oil return port 201 of the front axle steering oil tank assembly 2 ;

Preferably, the front axle steering pump 3 is installed on the engine. As shown in Figures 2-4, the front axle steering pump 3 has two oil port interfaces, the first interface 301 and the oil outlet of the front axle steering oil tank assembly 2 202 is connected, the second interface 302 is connected with the oil inlet P of the hydraulic power steering gear assembly 17, and its function is to provide a hydraulic power source for the front axle steering system;

As shown in Figures 2-5, the front axle steering oil tank assembly 2 includes a steering oil tank 203 and an oil tank bracket 204. The steering oil tank 203 is fixed on the vehicle body through the oil tank bracket 205, which has two oil circuit interfaces. They are the oil outlet 202 and the oil return port 201 respectively. The oil outlet 202 is connected to the oil inlet 301 of the steering pump 3, and the oil return port 201 is connected to the oil return port T of the hydraulic power steering gear assembly 1 and the rear axle steering integrated valve. The second port 8-T of the group 8 is connected, and its function is to provide a hydraulic source for the front axle steering system.

As shown in FIG. 3 , the rear axle steering integrated valve group 8 includes a valve body 24 , a three-position four-way proportional reversing valve 25 , two balance valves 26 , and four two-position two-way solenoid valves 27 , 28 , 30 and 31 As well as the two-position three-way solenoid valve 29 and the one-way valve 32 . The rear axle steering integrated valve group 8 is fixed on the vehicle body bottom plate through the through hole on the valve body 24, and it has 6 oil circuit interfaces, and the interface is preferably a ferrule type straight-through joint structure.

Preferably, the valve body 24 is a cubic structure, which includes six faces, the two balance valves 26, the four two-position two-way solenoid valves 27, 28, 30 and 31, and the two-position three-way solenoid valve valves 29. The one-way valve 32 is located on the first surface, and the four interfaces of the third interface 8-P2, the fourth interface 8-T2, the fifth interface 8-A, and the sixth interface 8-B are located perpendicular to the first surface. On the connected second surface, the first interface 8-P and the second interface 8-T are located on the third surface connected with the first surface and the second surface, the fourth surface is opposite to the third surface, and the three-position four-way The proportional reversing valve 25 is located in the middle position of the fourth surface.

Preferably, on the first face, the valves 27, 28 and 31 are located on the side away from the second face, from the third face to the fourth face, the valves 31, 28 and 27 are arranged in sequence; the side close to the second face Valves 29 and 30 are provided, and the valves 30 and 29 are arranged in sequence from the third surface to the fourth surface, and the valves 30 and 29 are arranged on the side close to the third surface; the one-way valve 32 is located between the valves 30 and 31; Two balancing valves 26 are located between valve 29 and the fourth face and between valves 27, 28 and the second face.

On the second face, the interfaces 8-P2 and 8-T2 are arranged on the side close to the first face, preferably on the side close to the third face, wherein from the third face to the fourth face, the ports 8-P2 and 8-T2 are arranged in sequence. P2, 8-T2; the interfaces 8-A, 8-B are arranged on the side away from the first surface, preferably on the side close to the fourth surface, from the third surface to the fourth surface, the interface 8-B is arranged in sequence from the third surface to the fourth surface. , 8-A.

On the third surface, the first interface 8-P and the second interface 8-T are disposed close to the first surface, wherein the first interface 8-P is farther from the second surface than the second interface 8-T.

The above structural layout can make the rear axle steering integrated valve group 8 more reasonable in structure, easy to process, occupy less space, more reasonable in oil circuit, small in pressure loss, convenient for pipe layout, and convenient for adjustment and operation of each control valve. Figure 3 shows the rear axle steering integrated valve group structure. The valve group structure is reasonable in layout, easy to process, occupies less space, more reasonable in the oil circuit, small in pressure loss, convenient for pipe layout, and convenient for adjustment and operation of each control valve. By adding a three-position four-way proportional valve, the opening of the spool can be precisely controlled, and then the expansion and contraction of the rear axle steering hydraulic cylinder with the target displacement can be precisely controlled to realize the closed-loop control of the steering hydraulic cylinder and steering wheel manipulation.

The first interface is the oil inlet port 8-P, which is connected to the oil outlet 110 of the rear axle steering pump assembly 11, and the second interface is the oil return port 8-T and the oil return port 401 of the rear axle steering oil tank assembly 4 connection; the third interface 8-P2 and the fourth interface 8-T2 are respectively connected with the first interface 59 and the second interface 58 of the unlocking cylinder 44 of the steering return locking mechanism assembly 7; the fifth interface 8-A, the first interface 58 The six ports 8 -B are connected with the first port 34 and the second port 33 of the rear axle steering hydraulic cylinder assembly 6 .

The function of the rear axle steering integrated valve group 8 is: according to the steering mode selected by the driver, receiving the switch signal provided by the all-wheel steering controller, and simultaneously controlling the four two-position two-way solenoid valve valves 27, 28, and 30 , valve 31, two-position three-way solenoid valve 29 to switch the oil circuit, so as to realize three modes of steering: front axle steering, front and rear axle same-direction steering, and front and rear axle reverse steering according to the steering mode required by the driver; rear axle steering The integrated valve group 8 receives the current signal provided by the all-wheel steering controller, controls the valve body opening of the three-position four-way proportional reversing valve 25, and realizes the smooth follow-up of the steering rod system of the rear axle to the steering of the front axle. Specifically: the two-position and two-way solenoid valves 27 and 28 are respectively connected in series with ports A, namely 8-A and B, namely between 8-B and T, namely 8-T. After the power is turned on, the rear axle The two cavities of the steering cylinder are connected and are in an unloading state; after the solenoid valve is powered off, the rear axle steering cylinder can build pressure, and the controller controls the rear axle steering hydraulic cylinder 6 piston rod by controlling the power supply current of the three-position four-way proportional reversing valve 25 The two balance valves 26 are connected in series between the three-position four-way proportional reversing valve 25 and the A port 8-A and B port 8-B respectively, which can protect the pressure of the two chambers of the rear axle steering hydraulic cylinder 6 The role of pressure to ensure the steady state of each position in the steering process; the two-position two-way solenoid valve 30 and the two-position three-way solenoid valve 29 are connected in series between P port 8-P, T port 8-T and P2 port 8-P2 port During the time, the controller controls the power supply of the two-position two-way solenoid valve 30 and the two-position three-way solenoid valve 29 to realize the charging and discharging of the rod cavity of the unlocking cylinder 44; Unified return to the rear axle steering oil tank assembly 4.

The rear axle steering integrated valve group 8 is an inventive point of the present invention. Through this invention, the rear axle can realize the steering mode among the three steering modes: front axle steering, front and rear axle same-direction steering, and front and rear axle reverse steering. Oil circuit switching.

As shown in FIG. 4, the rear axle steering hydraulic cylinder 6 includes a cylinder barrel 88, a piston rod 87, a ball stud 36, a clamp 90, and a cylinder displacement sensor 35, which has a first interface 34 and a second interface 33 through the high-pressure oil pipe The fifth port 8-A and the sixth port 8-B of the rear axle steering integrated valve group 8 are respectively connected; the oil cylinder displacement sensor 35 is installed inside the cylinder; The groove is machined, the ball head is screwed on the output end of the piston rod, and the groove is locked with a clamp to fix the screwing depth of the ball head. The fixed end of the cylinder barrel is processed with an annular groove, and the joint bearing is pressed into it, and the cylinder barrel is fixed at the attachment seat of the rear axle steering hydraulic cylinder through the pin shaft. One end of the rear axle steering hydraulic cylinder assembly 6 is connected with the vehicle body attachment seat through a joint bearing, and the other end is connected with the left swing arm 70 of the rear axle steering rod system 10 through the ball stud 36, so as to realize the rear axle steering hydraulic cylinder assembly 6. fixed, the first port 34 of the upper oil circuit of the rear axle steering hydraulic cylinder assembly 6 is connected to the fifth port 8-A of the rear axle steering integrated valve group 8, and the second port 33 is connected to the sixth port 8-A of the rear axle steering integrated valve group 8. Interface 8-B is connected.

FIG. 5 shows a schematic structural diagram of the steering return locking mechanism assembly 7 . As shown in FIG. 5, the steering return locking mechanism assembly 7 includes an unlocking cylinder 44, an unlocking spring 52, a return spring 56, a mechanical lock assembly 48, a rotating pin 60, a return cylinder 45, a telescopic cylinder 49, Telescopic shaft 40, left bearing fixing nut 41, left spring bearing assembly 55, right spring bearing assembly 57, retaining ring between cylinders 47, pin 50, unlocking spring bearing 54, unlocking cylinder upper bracket 43, The unlocking cylinder lower bracket 42 , the ball stud 38 , the locking sensor 46 , and the unlocking sensor 51 . The return spring 56 is arranged in the return cylinder 45, and the left and right ends of the return cylinder 45 are respectively connected to the unlocking cylinder bracket and the telescopic cylinder 49, wherein the unlocking cylinder bracket includes the unlocking cylinder upper bracket 43 and the unlocking cylinder lower bracket 42. The upper end of the bracket 43 is connected to one end of the unlocking oil cylinder 44, and the other end of the unlocking oil cylinder 44 is connected to a pin, which is the pin connecting the mechanical lock assembly 48 and the unlocking oil cylinder 44; one end of the unlocking spring 52 is hung on the mechanical lock The assembly 48 is connected to the pin shaft of the unlocking oil cylinder 44, and the other end is hung on the pin shaft of the unlocking spring support 54, and the unlocking spring support 54 is fixed on the upper end of the telescopic cylinder 49; one end of the mechanical lock assembly 48 is fixed on the telescopic cylinder 49 On; the telescopic shaft 40 extends into the return cylinder 45 and the telescopic cylinder 49.

The left and right ends of the return spring 56 are loaded into the return cylinder 45 through the left spring support assembly 55 and the right spring support assembly 57, and by pushing the left spring support assembly 55 and the right spring support assembly 57 respectively The return spring 56 is compressed to the left and right; the telescopic shaft 40 penetrates the return cylinder 45 and the telescopic cylinder 49, and can perform reciprocating and telescopic motions relative to the return cylinder 45 and the telescopic cylinder 49 without being locked; one end of the telescopic shaft 40 The pin shaft 50 is pressed into the radial direction through interference fit, and the other end is screwed into the left support fixing nut 41 and the ball stud 38; one end of the unlocking cylinder is connected to the upper bracket 43 of the unlocking cylinder by means of a pin shaft and a joint bearing, and the other end is connected with the upper bracket 43 of the unlocking cylinder. It is connected with the mechanical lock assembly 48 by means of a pin shaft and a joint bearing; the upper bracket 43 of the unlocking cylinder and the lower bracket 42 of the unlocking cylinder are clamped and fixed in the outer slot of the return cylinder 45 by four bolts; the unlocking spring support 54 passes through The bolt is fixed on the upper end of the telescopic cylinder 49; the device adopts two unlocking springs 52, one end of the unlocking spring 52 is hung on the pin shaft of the mechanical lock assembly 48 and the unlocking cylinder 44, and the other end is hung on the pin shaft of the spring support 54 . The mechanical lock assembly 48 is fixed on the telescopic cylinder 49 through the rotating pin shafts 60 on both sides, and the mechanical lock can rotate up and down around the rotating pin shafts 60 on both sides to complete the unlocking and locking of the telescopic shaft 40; the return cylinder 45 The retaining ring 47 between the cylinders and the telescopic cylinder 49 are connected by evenly distributed 8 bolts; the unlocking sensor support 61 is fixed on the flange surface of the return cylinder 45 by threaded connection, and the unlocking sensor 46 is fixed on the unlocking sensor by threaded connection. On the support 61, the lock sensor 51 is fixed on the mechanical lock assembly 48 through screw connection.

When the front axle is turned, the steering return locking mechanism assembly 7 is in the neutral position and locked. At this time, the return spring 56 drives the left spring support assembly 55 and the right spring support assembly 57 to contact the inner side of the return cylinder 45 and the retaining ring 47 between the cylinders respectively, thereby driving the telescopic shaft 40 to return to the initial neutral position After the return spring 56 returns to the neutral position, the oil ports 8-A and 8-B of the hydraulic valve group are controlled, so that the unloading cylinder 44 is in a free state, and the two unlocking springs 52 drive the mechanical lock assembly 48 to wind As the mechanical lock rotating pin 60 rotates downward, the semicircular slot of the mechanical lock assembly 48 is locked into the pin 50, and the telescopic shaft 40 cannot perform telescopic movement.

When the rear axle participates in steering, the steering return locking mechanism assembly 7 is in a state of unlocking and follow-up. At this time, the first interface 59 of the unlocking cylinder 44 is filled with oil, and the piston rod of the unlocking cylinder 44 shrinks, driving the mechanical lock assembly 48 to rotate upward around the mechanical lock rotating shaft 60 until the signal light of the unlocking sensor 46 lights up, the mechanical lock assembly 48 Unlock in place; at this time, the telescopic shaft 40 can perform reciprocating telescopic movement as required by the movement of the subsequent axle steering rod system: when the telescopic shaft 40 is retracted, the nut 41 pushes the left spring support assembly 55 to move to the right with the telescopic shaft 40, and the right spring supports The seat assembly 57 is in close contact with the retaining ring 47 between the cylinder blocks, and the compression of the telescopic shaft 40 is realized by compressing the return spring 56 to the right; The left spring support assembly 55 is in close contact with the inner surface of the return cylinder 45, and the extension of the telescopic shaft 40 is realized by compressing the return spring to the left.

One end of the steering return locking mechanism assembly 7 is connected with the vehicle body attachment through a joint bearing, and the other end is connected with the right swing arm 71 of the rear axle steering rod system 10 through the ball stud 38, so as to realize the overall steering return locking mechanism. The first port 59 and the second port 58 of the oil circuit of the unlocking cylinder 44 are connected to the third port 8-P2 and the fourth port 8-T2 of the rear axle steering integrated valve group 8.

The steering return locking mechanism assembly of FIG. 5 . When the rear axle is steered normally, it can complete the follow-up expansion and contraction with the rear axle steering hydraulic cylinder; when the rear axle does not steer, it can keep the rear axle steering rod tied in the middle position, mechanically maintaining and rigidly locked; the all-wheel steering system appears electrical Or in the event of hydraulic failure, it can realize passive active return and complete rigid locking, which greatly improves the reliability of the entire set of all-wheel steering.

The all-wheel steering mode switch is integrated inside the vehicle control panel and operated by the driver. It has three working modes: "front axle steering", "front and rear axle steering in the same direction" and "reverse steering of front and rear axles". As shown in Figures 1 to 7, the features of the working principle of a high-reliability electromechanical-electrical-hydraulic all-wheel steering device involved in the patent of the present invention are as follows:

(1) "Front axle steering" mode

In the "front axle steering" mode, the all-wheel steering mode switch is in the front axle steering state, the driver turns the steering wheel, and the steering wheel angle signal is sent to the steering controller. The solenoid valve 31 is powered off, and at the same time, the first port 8-P and the second port 8-T in the rear axle steering integrated valve group 8 are controlled to be unblocked. The purpose is to unload the unlocking cylinder 44, and the unlocking spring 52 drives the mechanical lock. 48 is locked and is in a locked state, ensuring that the rear axle is in the neutral position and does not participate in steering.

(2) "Front and rear axle steering in the same direction" mode

In the "front and rear axle steering in the same direction" mode, the oil circuit of the first port 8-P and the third port 8-P2 in the rear axle steering integrated valve group 8 is unblocked, and the oil circuit of the second port 8-T and the fourth port 8-T2 The purpose is to fill the rod cavity of the unlocking cylinder 44 with oil, and drive the mechanical lock 48 to rotate up around the rotating shaft to complete the unlocking; the controller controls the two-position two-way solenoid valve 27 and valve 28 to power on, and realizes the rear axle steering hydraulic cylinder 6 When the driver turns the steering wheel, the steering wheel angle sensor 13 sends the steering wheel angle signal to the steering controller 9, and the control system calculates the target displacement of the rear axle steering hydraulic cylinder 6 according to the control strategy of the front and rear axles steering in the same direction. The current control of the three-position four-way proportional reversing valve 25 accurately realizes the displacement stroke of the rear axle steering hydraulic cylinder 6, and pushes the left steering rocker arm 70 to rotate through the ball stud 36, which drives the rear axle steering rod system to realize the rear axle following the front axle. turn in the same direction;

(3) "Front and rear axle reverse steering" mode

In the "reverse steering of front and rear axles" mode, the oil circuit of the first port P8-P and the third port 8-P2 in the rear axle steering integrated valve group 8 are unblocked, and the oil circuit of the second port T8-T and the fourth port 8-T2 The purpose is to fill the rod cavity of the unlocking cylinder 44 with oil, and drive the mechanical lock 48 to rotate up around the rotating shaft to complete the unlocking; the controller controls the two-position two-way solenoid valve 27 and valve 28 to power on, and realizes the rear axle steering hydraulic cylinder 6 When the driver turns the steering wheel, the steering wheel angle sensor 13 sends the steering wheel angle signal to the steering controller 9, and the control system calculates the target displacement of the rear axle steering hydraulic cylinder 6 according to the control strategy of the reverse steering of the front and rear axles. The current control of the three-position four-way proportional reversing valve 25 accurately realizes the displacement stroke of the rear axle steering hydraulic cylinder 6, and pushes the left steering rocker arm 70 to rotate through the ball stud 36, which drives the rear axle steering rod system to realize the rear axle following the front axle. reverse steering.

As shown in FIG. 6 , the rear axle steering pump assembly 11 includes a motor and a rear axle steering pump, which has an oil inlet 111 and an oil outlet 110 . The oil outlet 110 is connected to the first port P port 8-P of the rear axle steering integrated valve group 8 through the high pressure oil pipe; the oil inlet 111 is connected to the second port T port 8-T of the rear axle steering integrated valve group 8 through the low pressure oil pipe Connection; fixed on the vehicle body attachment by bolting.

In the two working modes of "front and rear axles steering in the same direction" and "reverse steering of front and rear axles", the controller needs to calculate the steering of the rear axle by reading the signal of the steering wheel angle sensor 13 when the driver turns the steering wheel. The target position of the hydraulic cylinder 6 controls the opening of the spool of the three-position four-way proportional valve 25 in the current control mode, and finally realizes that the steering hydraulic cylinder expands and contracts to the absolute target position, and finally drives the rear axle steering rod system 10 to realize the same adjustment to the front axle. Rotate forward and reverse. In the control system, the intelligent target displacement function is innovatively proposed. Specifically, the controller estimates the value of the steering angle of the front axle wheel according to the value collected by the steering wheel angle sensor, combined with the transmission ratio of the hydraulic steering gear of the front axle and the angular transmission ratio of the steering rod system of the front axle, and then according to the same direction or reverse direction The model combines the corresponding co-directional coefficient and reverse coefficient to determine the value of the wheel steering angle of the rear axle, and then combines the angular transmission ratio of the steering rod system of the rear axle to obtain the target turning angle of the left swing arm 70. The rear axle steering hydraulic pressure is installed by the left swing arm. The arm length of the cylinder 6 is calculated to obtain the target displacement value of the piston expansion and contraction of the rear axle steering hydraulic cylinder 6 . Its basic method is as follows:

Where: θ _sw is the steering wheel angle (°), which is the value collected by the angle sensor, and the preferred range is -900° to 900°;

L is the wheelbase of the vehicle (mm), which belongs to the overall layout parameter of the vehicle, and the preferred range is (2800-3200);

L _g is the piston telescopic target displacement value of the rear axle steering hydraulic cylinder 6; the output value is calculated for the system;

L _gg is the distance (mm) from the center hole of the left swing arm 70 in the rear axle steering rod system to the axis of the ball stud 36 for installing the rear axle steering hydraulic cylinder 6, preferably in the range (180-280);

i _f is the angular transmission ratio of the steering rod system of the front axle, preferably in the range of 0.8 to 1.3;

i _R is the angular transmission ratio of the rear axle steering rod system, preferably in the range of 0.8 to 1.3;

i _T is the steering coefficient of the front and rear axles in the same direction, preferably in the range of 0.2 to 0.8;

i _q is the transmission ratio of the hydraulic power steering gear, which is a constant. preferably 26;

λ is the equivalent wheelbase coefficient of the distance between the front axle and the instantaneous center of steering, which is obtained through calculation, and is preferably 0.6 to 0.8. The "wheelbase" of an all-wheel steered vehicle is different from that of a front-axle steered vehicle. It is not the distance between the two axles in a simple sense, but the longitudinal distance from the axle to the instantaneous center of the steering. A "virtual rear axle" is established for the all-wheel steered vehicle. In the analysis, the "virtual rear axle" is regarded as the rear axle of the front axle steered vehicle, which corresponds to the unsteered rear axle of the front axle steered vehicle, and the front axle of the vehicle is along the longitudinal centerline. The distance to the instantaneous center of steering is the "equivalent wheelbase". The ratio of the equivalent wheelbase to the wheelbase is the equivalent wheelbase coefficient, and the determination of this parameter is closely related to the minimum steering radius of the vehicle. See Figure 9 for details. In Figure 9, L is the wheelbase, and λ is the equivalent wheelbase coefficient between the front axle and the instantaneous center of steering.

The present invention has developed a brand-new calculation method for the target displacement value of the piston expansion and contraction of the rear axle steering hydraulic cylinder 6 through a large amount of research. The target displacement function can accurately realize the closed-loop control of the steering hydraulic cylinder and the steering wheel manipulation, and the control is precise; it has safe and reliable performance, which greatly improves the safety and stability of the system, and the system design is stable and reliable, which can ensure the safety of the vehicle.

For safety reasons, if the driver fails to switch to the front axle steering mode in time when the vehicle speed exceeds the limit, the all-wheel steering controller will automatically switch to the front axle steering mode; when an electro-hydraulic failure occurs in the system, the rear axle steering hydraulic cylinder will Unloading, the passive self-aligning and locking device of the rear axle can drive the steering rod of the rear axle to return to the neutral position, and control the mechanical lock to complete the mechanical lock of the rear axle.

The device is a highly reliable electro-hydraulic all-wheel steering system with passive neutral alignment and rigid locking functions of the steering axle. The driver can realize three steering modes according to the actual road conditions. Front axle steering mode, front and rear axle co-phase steering Mode, front and rear axle out-of-phase steering mode) switching, can simultaneously have the dynamic response and shock resistance of the follow-up steering axle in complex environments, the follow-up steering axle under nonlinear loads The neutral steering stiffness and system failure, vehicle damage Compared with the existing all-wheel steering system, the present invention has the following advantages:

1. The highly reliable electro-hydraulic all-wheel steering system of the present invention has simple structure, stable operation and high reliability. The front and rear axles adopt independent hydraulic sources, and the steering system can realize three steering modes (front axle steering mode, At the same time, from the perspective of active safety, the safety mode can be switched independently according to the actual vehicle safety needs.

2. The present invention designs a steering return locking mechanism assembly, which is the core component of the device and a key component to ensure the reliability and safety of the all-wheel steering vehicle. The mechanism can realize follow-up steering according to the controller's command when the rear steering axle participates in steering; when the rear steering axle does not need to be turned, it can follow the controller's command to turn back to the neutral position, and complete the mechanical locking of the rear axle through the mechanical structure. , reliable and stable; when the vehicle has unforeseen failures, it can drive the rear steering axle to passively return to the neutral position, and complete the mechanical locking of the rear axle through the mechanical structure. This automatic passive return to the neutral position and locking mechanism greatly improves the safety of the all-wheel steer vehicle, which cannot be achieved by the previous all-wheel steer system.

3. The present invention designs a rear axle steering integrated valve group for the all-wheel steering system. The valve group has a high degree of integration and precise control. The precise steering of the rear steering axle is realized by precisely controlling the proportional valve.

It should be noted that those skilled in the art can easily understand that the heavy-duty recirculating ball dual-mode electric power steering device involved in the patent of the present invention can be applied in the steering system of different types of wheeled vehicles with manned and unmanned driving in the above manner. , and various modifications and changes may be made to the patent of the present invention without departing from the spirit and scope of the patent of the present invention as defined by the appended claims.

Although the present invention has been disclosed above with preferred embodiments, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be based on the scope defined by the claims.

Claims (4)

1. the calculation method of the target position of a rear axle steering hydraulic cylinder, it is characterized in that, when the controller all needs when the driver turns the steering wheel, by reading the signal of the steering wheel angle sensor, calculates the target position of the rear axle steering hydraulic cylinder , control the opening of the spool of the three-position four-way proportional valve in the current control mode, and finally realize the telescoping of the steering hydraulic cylinder to the absolute target position, and finally drive the rear axle steering rod system to realize the same and reverse rotation of the front axle; Its control method is as follows:

Among them: θ _sw is the steering wheel angle, which is the value collected by the angle sensor, and the range is -900°～900°; L is the wheelbase of the vehicle, which belongs to the overall layout parameter of the vehicle, ranging from 2800mm to 3200mm; L _g is the piston telescopic target displacement value of the rear axle steering hydraulic cylinder; the output value is calculated for the system; L _gg is the distance from the center hole of the left swing arm in the rear axle steering rod system to the axis of the ball stud for installing the rear axle steering hydraulic cylinder, and the range is 180mm to 280mm; i _f is the angular transmission ratio of the steering rod system of the front axle, ranging from 0.8 to 1.3; i _R is the angular transmission ratio of the rear axle steering rod system, ranging from 0.8 to 1.3; i _T is the steering coefficient of the front and rear axles in the same direction, ranging from 0.2 to 0.8; i _q is the transmission ratio of the hydraulic power steering gear, which is a constant; λ is the equivalent wheelbase coefficient of the front axle from the instantaneous center of steering. 2. The method according to claim 1, wherein the controller estimates the steering wheel steering of the front axle in combination with the transmission ratio of the hydraulic steering gear of the front axle and the angular transmission ratio of the steering rod system of the front axle according to the value collected by the steering wheel angle sensor. The value of the steering angle of the rear axle is then determined according to the same-direction or reverse mode combined with the corresponding same-direction coefficient and reverse coefficient, and then combined with the angular transmission ratio of the rear-axle steering rod system to obtain the target rotation angle of the left swing arm , the left swing arm is installed with the rear axle steering hydraulic cylinder, and the arm length of the rear axle steering hydraulic cylinder is calculated to obtain the piston telescopic target displacement value of the rear axle steering hydraulic cylinder. 3. A 4X4 electro-hydraulic all-wheel steering system, characterized in that it comprises a rear axle steering hydraulic cylinder (6), the rear axle steering hydraulic cylinder (6) comprising a cylinder (88), a piston rod (87), a ball The head pin (36), the clamp (90), and the oil cylinder displacement sensor (35) have a first interface (34) and a second interface (33) respectively connected to the A port of the rear axle steering integrated valve group and the rear axle through an oil pipe Port B of the steering integrated valve group; the cylinder displacement sensor (35) is installed inside the cylinder barrel; one end of the rear axle steering hydraulic cylinder (6) is connected to the vehicle body attachment through a joint bearing, and the other end is connected to the rear axle through a ball stud (36). The left swing arm (70) of the axle steering rod system (10) is connected to realize the fixation of the rear axle steering hydraulic cylinder (6), and the first interface (34) of the upper oil circuit of the rear axle steering hydraulic cylinder (6) is connected with the rear axle steering The A port of the rear axle steering integrated valve group of the integrated valve group (8) is connected, and the second port (33) is connected to the B port of the rear axle steering integrated valve group of the rear axle steering integrated valve group (8). The rear axle The method described in any one of claims 1-2 is adopted for the target displacement value of the piston expansion and contraction of the steering hydraulic cylinder. 4. steering system as claimed in claim 3, described system comprises steering wheel and steering gear assembly, front axle steering oil tank assembly, front axle steering pump, rear axle steering oil tank assembly, front axle steering rod system, Steering return locking mechanism assembly, rear axle steering integrated valve group, all-wheel steering controller assembly, rear axle steering rod system, rear axle electric steering pump assembly, steering wheel and steering gear assembly and front axle steering rod system Connection; the front axle steering pump is installed on the engine, which is driven by the engine to provide power to the system; the oil outlet of the front axle steering oil tank assembly is connected to the oil inlet end of the front axle steering pump through an oil pipe, and the oil return port is connected to the steering wheel and steering wheel The oil return port of the power steering gear assembly in the power steering gear assembly is connected by an oil pipe; The oil outlet of the rear axle steering oil tank assembly is connected with the oil inlet end of the rear axle electric steering pump assembly through an oil pipe, and the oil return port is connected with the oil return port T of the rear axle steering integrated valve group through an oil pipe; the rear axle electric steering The oil outlet of the pump assembly is connected with the oil inlet end of the rear axle steering integrated valve group through an oil pipe; the first interface of the rear axle steering hydraulic cylinder is connected with the A port of the rear axle steering integrated valve group through an oil pipe, and the rear axle steering hydraulic cylinder is connected by an oil pipe. The second interface is connected with the B port of the rear axle steering integrated valve group through the oil pipe, the rear axle steering hydraulic cylinder is connected with the left swing arm of the rear axle steering rod system, and the first interface of the unlocking cylinder of the steering return locking mechanism assembly It is connected with the P2 port of the rear axle steering integrated valve group through an oil pipe, and the second port of the unlocking cylinder of the steering return locking mechanism assembly is connected with the T2 port of the rear axle steering integrated valve group through an oil pipe. It is connected with the right swing arm of the steering rod system of the rear axle.

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