Four-wheel steering suspension system and control method for new energy vehicles

Abstract

The present invention discloses a four-wheel steering suspension system and a control method for a new energy vehicle, belonging to the technical field of the chassis of a new energy vehicle. Among them, the four-wheel steering suspension system of the new energy vehicle includes a front wheel assembly, which includes a left front wheel and a right front wheel, a suspension structure connecting the two wheels and a steering gear, and the steering gear is controllably connected to and controls the rotation direction and angle of the left front wheel and the right front wheel; a rear wheel assembly, which includes a left rear wheel and a right rear wheel, a suspension structure connecting the two wheels, and steering components are arranged in the suspension structure, and the steering components are used to independently control the rotation direction and angle of the left rear wheel and the right rear wheel; a controller, according to the instruction of the vehicle control host, controls the steering components to independently control the rotation direction and angle of the left rear wheel and the right rear wheel.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy vehicle chassis, and particularly to a four-wheel steering suspension system and a control method for new energy vehicles. Background Art

[0002] The rear-wheel steering of a vehicle means that in addition to the front-wheel steering, the angle of the rear wheels can also be adjusted to assist in steering. In this way, the rear wheels can deflect in the same direction as the front wheels at low speeds and in the opposite direction at high speeds. It can improve the vehicle's flexibility. When parking or turning around at low speeds, the rear wheels deflecting in the same direction as the front wheels can make the vehicle body more flexible and reduce the turning radius. It can also enhance stability. During high-speed driving, the rear wheels deflecting in the opposite direction helps to improve the vehicle's straight-line stability and the response speed when changing lanes.

[0003] Therefore, in some high-performance vehicles, especially new energy vehicles that are vigorously developed in China, both front-wheel and rear-wheel steering systems are equipped, that is, the so-called four-wheel steering suspension system. It combines the advantages of front-wheel steering and rear-wheel steering, automatically adjusts the angles of the front and rear wheels under different speed conditions to achieve the best handling effect and safety, and plays corresponding advantages in multiple usage scenarios.

[0004] However, in the existing rear-wheel steering structure, the main body usually follows the integrated steering seat structure of the front-wheel steering. Due to the complex structure of the rear wheels and the rear axle position, multiple components need to be arranged, such as arranging a four-wheel drive system, part of the battery or fuel tank, or when arranging the motor and drive structure, it is easy to have situations such as unreasonable structural configuration or occupying the interior space of the carriage. At the same time, when the rear wheels are running, especially when the vehicle is running at high speed, the stability requirements for the rear wheels are extremely high. A slight deviation will cause the vehicle to exhibit abnormal attitude phenomena with a control difficulty exceeding expectations. Especially in the face of special situations such as wet and slippery roads, abnormal potholes or flat tires, the traditional rear-wheel steering structure still has multiple deficiencies. Therefore, more attempts and research are needed for the four-wheel steering of new energy vehicles. Summary of the Invention

[0005] The purpose of the present invention is to provide a four-wheel steering suspension system and a control method for new energy vehicles, by improving the rear-wheel steering structure of the vehicle, providing vehicle controllability, and achieving targeted control in multiple usage scenarios.

[0006] To achieve the above purpose, the technical solution of the present invention is as follows:

[0007] The four-wheel steering suspension system of a new energy vehicle includes

[0008] A front-wheel assembly, including a left front wheel and a right front wheel, a suspension structure and a steering gear connecting the two wheels, and the steering gear is controlled and connected to control the rotation direction and angle of the left front wheel and the right front wheel;

[0009] Rear wheel assembly, including a left rear wheel and a right rear wheel, a suspension structure connecting the two wheels, and steering components arranged in the suspension structure for independently controlling the rotation direction and angle of the left rear wheel and the right rear wheel;

[0010] A controller, according to the instructions of the vehicle control host, controls the steering components to independently control the rotation direction and angle of the left rear wheel and the right rear wheel;

[0011] A rotation angle sensor is arranged at the steering component for real-time acquisition of the current rotation angle value of the left rear wheel or the right rear wheel and feedback of the rotation angle value to the vehicle control host;

[0012] The steering component is arranged at the lower swing arm or lower link of the left rear wheel and the right rear wheel, one end is hinged to the steering seat through a ball joint component, and the other end is hinged to the lower swing arm or lower link. A rotation driving mechanism is arranged at the hinge of the lower swing arm or lower link. The rotation driving mechanism is connected to the controller and drives the corresponding rotation of the steering seat through a link component.

[0013] Further, the steering component includes a first link and a second link. The first link is connected to the steering arm of the steering seat through a first ball joint. The other end of the first link is hinged to the second link. The other end of the second link is connected to the lower swing arm or lower link through a second ball joint. A rotation driving mechanism is arranged on the second link.

[0014] Further, the first ball joint is arranged at the lower side position behind the vehicle's forward driving direction of the wheel center point.

[0015] Further, the second ball joint is arranged at a position close to the installation structure of the lower swing arm or lower link and the vehicle frame.

[0016] Further, the second link extends outward at the hinge with the first link and is provided with a hinge structure. A third ball joint is arranged at the lower swing arm or lower link. A driving mechanism is arranged between the third ball joint and the hinge structure. The driving mechanism is used to drive the second link and make it rotate around the second ball joint, so that the steering component constructs a triangular stress structure with the first link and the second link as the framework and a triangular stress structure with the second link and the driving mechanism as the framework.

[0017] Further, a locking mechanism is arranged at the front end of the second link for restricting the rotation of the second link and keeping the corresponding wheel in a straight driving state.

[0018] Further, a V-shaped groove is arranged at the front end of the second link. The locking mechanism includes a block and a block driving mechanism. The front end of the block is provided with a V-shaped protrusion, and the front end of the V-shaped protrusion can be embedded in the V-shaped groove.

[0019] A four-wheel steering control method, applied to the above four-wheel steering suspension system, includes:

[0020] The control host obtains the driving speed value V and the front-wheel steering angle A of the current vehicle through vehicle functional components;

[0021] If the driving speed value V is greater than the first set value V1 and the front-wheel steering angle value A is greater than the first set value A1, the controller deflects the rear wheels in the same direction as the front-wheel steering angle, and the deflection angle of the rear wheel on the outer side of the turn is greater than that of the rear wheel on the inner side of the turn;

[0022] If the driving speed value V is less than the second set value V2 and the front-wheel steering angle value A is greater than the second set value A2, the controller deflects the rear wheels in the direction opposite to the front-wheel steering angle, and the deflection angle of the rear wheel on the outer side of the turn is greater than that of the rear vehicle on the inner side of the turn;

[0023] If the driving speed value V is negative and the front-wheel steering angle value A is greater than the second set value A2, the controller deflects the rear wheels in the direction opposite to the front-wheel steering angle, and the deflection angle of the rear wheel on the outer side of the turn is greater than that of the rear vehicle on the inner side of the turn.

[0024] A control method for stable vehicle driving, applied to the above four-wheel steering suspension system, includes:

[0025] The control host obtains the driving speed value V and the front-wheel steering angle A of the current vehicle through vehicle functional components;

[0026] The control host obtains the rotation speed conditions of the current four tires through the ABS sensing components of the wheels;

[0027] When the rotation speed of the left front wheel or the right front wheel is significantly less than that of the other three wheels, and the driving speed value V is greater than the third set value V3 and the front-wheel steering angle value A is greater than the third set value A3, the controller deflects the rear wheels in the same direction as the front-wheel steering angle;

[0028] When the rotation speed of the left rear wheel or the right rear wheel is significantly less than that of the other three wheels, and the driving speed value V is greater than the third set value V3, the controller deflects the normal rear wheels in the same direction as the front wheels and performs a straight-line locking operation on the abnormal rear wheels.

[0029] Further, when the rotation speed of the left rear wheel or the right rear wheel is significantly less than that of the other three wheels, and the driving speed value V is greater than the third set value V3 and the front-wheel steering angle value A is greater than the third set value A3, the controller deflects the normal rear wheels in the same direction as the front-wheel steering angle.

[0030] Adopting this solution and comparing with the prior art, it has the following advantages:

[0031] The four-wheel steering suspension system of new energy vehicles in this solution is applied to new energy vehicles. Through electronic control and the vehicle host, the steering control of the four wheels, especially the rear wheels, can be implemented. Through the cooperation of the steering control of the front wheels and the rear wheels, functions such as high-speed fast lanes and low-speed turning with a small turning radius can be achieved. This solution adopts an independent rear-wheel component structure, that is, the left and right rear wheels adopt completely independent steering components, and the steering components are completely arranged at the lower swing arm or lower link of the rear wheels. At the same time, a lightweight structure is arranged to reduce the unsprung mass. Compared with the traditional rear-wheel steering system with an integrated steering gear structure, it does not need to occupy the rear-wheel chassis space, and can perform separate and precise angle control on the left and right rear wheels, so as to realize the rear-wheel functions in multiple scenarios in real time, greatly improving the driving functionality and stability of the vehicle;

[0032] The steering component in this solution is framed at the lower swing arm or lower link, without the need for a large-scale redesign of the structure of the existing vehicle, and is implemented through the driving mechanism of the first link, the second link and the high-precision servo cylinder. The first link and the second link form a triangular force-bearing structure, and the second link and the driving mechanism form a triangular force-bearing structure, greatly improving the structural stability. The main body of the rotational force of the wheel is transmitted to the subframe through the structure of the first link and the second link, reducing the force distribution on the servo cylinder driving mechanism, and the configuration of changing a large stroke to a small angle improves the accuracy of wheel rotation and the controllability of the servo cylinder driving mechanism. At the same time, arranging the entire steering component at the lower swing arm or lower link can reduce the influence of the up and down shock movement of the vehicle driving wheels on the steering system, making its working interference less and the work more stable;

[0033] A locking mechanism is arranged at the end of the second link of the steering component in this solution, which can perform locking operations when the rear wheels are in a straight state during normal vehicle driving. Therefore, the running stability of the vehicle is greatly improved, and the servo cylinder driving mechanism for controlling the rear-wheel steering can be reduced to the standby state, which can reduce its working intensity and improve its service stability and service life;

[0034] A four-wheel steering control method in this solution realizes application functions in multiple scenarios through independent angle control of the rear wheels. Especially by implementing different rear-wheel deflection angles on the two rear wheels, in the scenario of relatively high-speed vehicle driving, the tracking performance of the vehicle can be improved, and the occurrence of side slip, oversteering or understeering can be reduced; when the vehicle is in scenarios such as low-speed turning or reverse parking, the driving stability of the vehicle can be improved, the turning radius can be reduced, and the convenience of turning and entering and leaving the parking space can be improved;

[0035] This solution provides a vehicle driving stability control method, specifically for situations such as wheel anomalies (e.g., tire blowouts) at high speeds. In such situations, the driver, due to unilateral pull, is prone to excessive steering in the opposite direction, potentially causing the vehicle to lose control or roll over. By steering the rear wheels in the same direction as the front wheels, this solution can reduce oversteer and rollover, thereby significantly improving stability and controllability in extreme situations.

[0036] This solution can perform differentiated and functional operations in multiple vehicle driving scenarios by performing completely independent control and adjustment of the rear wheels. It has excellent promotion significance and will play a positive role in my country's new energy vehicle technology and applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 Schematic diagram of the structure of the vehicle of the preferred embodiment.

[0038] Figure 2 Schematic diagram of the rear wheel assembly structure of a vehicle.

[0039] Figure 3 Schematic diagram of the steering component layout for the right rear wheel.

[0040] Figure 4 It is a structural diagram of the steering component.

[0041] Figure 5 A top view of the steering component.

[0042] Figure 6 This is a simplified structural diagram of the rotating state.

[0043] Figure 7 Schematic diagram of the locking mechanism structure.

[0044] Figure 8 This is a schematic diagram of the four-wheel structure of the vehicle in a straight line state.

[0045] Figure 9 This is a schematic diagram of the four-wheel structure in the first working state.

[0046] Figure 10 This is a schematic diagram of the four-wheel structure in the second working state.

[0047] Figure 11 This is a schematic diagram of the four-wheel structure in the third working state.

[0048] Figure 12 This is a schematic diagram of the four-wheel structure in the fourth working state. DETAILED DESCRIPTION

[0049] refer to Figures 1 to 5 , a four-wheel steering suspension system for new energy vehicles, including

[0050] The front-wheel assembly includes a left front wheel and a right front wheel, a suspension structure connecting the two wheels, and a steering gear 11. The steering gear 11 controls the connection and controls the rotation direction and angle of the left front wheel and the right front wheel;

[0051] The rear-wheel assembly includes a left rear wheel and a right rear wheel, and a suspension structure connecting the two wheels. Steering components 2 are arranged in the suspension structure. The steering components 2 are used to independently control the rotation direction and angle of the left rear wheel and the right rear wheel;

[0052] The controller, according to the instructions of the vehicle control host, controls the steering components to independently control the rotation direction and angle of the left rear wheel and the right rear wheel;

[0053] The rotation angle sensor is arranged at the steering component 2, and is used to obtain the current rotation angle value of the left rear wheel or the right rear wheel in real time, and feed back the rotation angle value to the vehicle control host;

[0054] Specifically, the four wheels of the vehicle are installed at the subframe 10 through the suspension structure. The subframe 10 is connected to the vehicle body 1 and constructs the entire vehicle body structure. Among them, the left front wheel and the right front wheel receive the control of the driver through the steering gear 11, or receive the control of the vehicle control host in the case of intelligent driving, to realize the synchronous rotation control of the left front wheel and the right front wheel, and further control the driving direction of the vehicle;

[0055] In order to realize the steering control of the rear wheels, the left rear wheel and the right rear wheel are connected to the subframe 10 through the lower control arm 12. A ball joint is arranged at the front end of the lower control arm 12. The ball joint is connected to a steering seat 14. Structures such as a spring and a shock absorber are arranged above the steering seat 14 to realize the up and down shock absorption movement of the wheel 13 and realize the function of rotating around the ball joint.

[0056] It should be noted that the suspension structure of the wheel has multiple mainstream structures, such as MacPherson suspension, double wishbone suspension or multi-link suspension, etc. Generally speaking, if the steering control of the wheel is to be implemented, a rotatable shaft mechanism in the vertical direction and a driving mechanism for driving the installation part (steering seat) of the vehicle to rotate around the shaft are required. This solution is described with a lower control arm structure, but it does not mean that this solution is only limited to being used in this lower control arm structure. Those skilled in the art can also apply it to various vehicle suspension structures through this solution;

[0057] The steering component 2 is arranged at the lower swing arms of the left and right rear wheels. The steering component 2 includes a first connecting rod 21 and a second connecting rod 22. The first connecting rod 21 is connected to the steering arm 15 of the steering seat 14 through a first ball joint. The other end of the first connecting rod 21 is hinged to the second connecting rod 22. The other end of the second connecting rod 22 is connected to the lower swing arm 2 through a second ball joint. Among them, the first ball joint is arranged at the lower side position behind the center point of the wheel 13 in the vehicle's forward driving direction. By arranging the first ball joint behind the forward movement, the steering component 2 can form a traction and drag structure, which can improve the driving stability and reduce the impact on the steering component in various situations; the second ball joint is arranged at a position close to the installation structure of the lower swing arm 12 and the subframe 10. Such an arrangement can make the best use of the space of the lower swing arm 12, extend the lengths of the first connecting rod 21 and the second connecting rod 22, thereby reducing the influence during the up and down shock absorption movement of the wheel, and making the force on the second ball joint be transmitted to the subframe in the shortest way.

[0058] The second connecting rod 22 extends outward at the hinge joint with the first connecting rod 21 and is provided with a hinge structure. A third ball joint is arranged at the lower swing arm 12. A high-precision servo cylinder 23 is arranged between the third ball joint and the hinge structure. The servo cylinder 23 is connected to the controller and is used to drive the second connecting rod 22 and make it rotate around the second ball joint. Generally speaking, the extended second swing arm 22 is used to increase the force arm, reduce the force on the servo cylinder 23, and make the rotation control more accurate and reliable with a large movement stroke.

[0059] Therefore, at the lower swing arm 12, the steering component 2 constructs a triangular force-bearing structure with the first connecting rod 21 and the second connecting rod 22 as the framework, and a triangular force-bearing structure with the second connecting rod 22 and the servo cylinder 23 as the framework. Through these two triangular force-bearing structures sharing the second connecting rod 22, the entire steering component 2 can be more evenly stressed and the rotation control can be more accurate and reliable. At the same time, within the designed rotation angle, the steering component 2 is always arranged within the corresponding space frame of the lower swing arm and will not invade other body spaces.

[0060] Reference Figure 6, in this embodiment, the maximum steering angle of the rear wheels is designed with a standard of ±10° (where red indicates a +10° deflection of the wheel and blue indicates a -10° deflection) (it should be noted that through appropriate structural optimization, its maximum rotation angle can be greater than ±10° as the design standard). The corresponding rotation angle of the second link 22 is 39.16°. Therefore, the rotation angle at the second link 22 is magnified by 1.958 times; the rotation stroke of the first ball joint is 22.62 units, and the corresponding stroke at the front end of the servo cylinder 23 is 46.92 units. Therefore, the stroke of the servo cylinder 23 is correspondingly magnified by 2.07 times; at the same time, through the force-bearing structures of these two triangles, for the impact force on the wheel, the main body is transmitted from the second ball joint to the lower swing arm 12 and the subframe 10, and the servo cylinder 23 is assigned a relatively small force. Therefore, from this structure, the working intensity of the servo cylinder 23 can be greatly reduced, and its controllability and stability can be improved.

[0061] Reference Figure 7 , in some embodiments, a locking mechanism 3 is arranged at the front end of the second link 22. The locking mechanism 3 is used to limit the rotation of the second link 22 and keep the corresponding wheel 13 in a straight-ahead driving state all the time. Specifically, a V-shaped groove is arranged at the front end of the second link 22. The locking mechanism 3 includes a mounting seat 34 ( Figure 7 The mounting seat shown in the figure is its sectional structure), a clamping block 31, and an electromagnetic cylinder 35. The mounting seat 34 is fixedly installed on the lower swing arm 12 correspondingly. The front end of the clamping block 31 is provided with a V-shaped protrusion. The front end of this V-shaped protrusion can be embedded in the V-shaped groove arranged on the second link 22. The rear end of the clamping block 31 is provided with two straight rods 32. The straight rods 32 are restricted to be installed at the mounting seat 34. A compression spring 33 is arranged on the straight rods 32. The compression spring 33 forces the clamping block 32 to fit towards the V-shaped groove of the second link 22 and makes the two fit tightly. An electromagnetic cylinder 35 is arranged at the middle position between the two straight rods 32. The electromagnetic cylinder 35 is installed inside the mounting seat 34. The actuator of the electromagnetic cylinder 35 is connected to the rear end of the straight rod 32 and is used to force the straight rod 32 and the clamping block 31 to move away from the V-shaped groove and realize the separated state of the clamping block 31 and the V-shaped groove. The electromagnetic cylinder 35 is connected to the controller.

[0062] In terms of electrical connection, in current new energy vehicles, the on-vehicle host, that is, the vehicle control host, controls the vehicle through the driver's operation or intelligent driving operation. In this solution, the vehicle control host collects data including the vehicle's working conditions and other data through multiple components and implements corresponding operations. The vehicle control host is connected to the servo cylinder 23, the electromagnetic cylinder 35, and the rotation angle sensor through a controller. Among them, the servo cylinder 23 can be a drive structure with a worm and worm gear to achieve a self-locking function. The servo cylinder 23 matches the deflection angle of the corresponding rear wheel according to the initially set stroke relationship. The rotation angle sensor can be arranged at the second ball head, and the current rotation angle of the second connecting rod can be accurately obtained through a high-precision combined Hall sensor, so as to achieve its precise angle control and angle holding. The electromagnetic cylinder 35 is in a closed state in most cases. At this time, the locking mechanism 3 implements the locking operation on the second connecting rod 22. Since the V-shaped groove has a large-angle opening, the actual stroke of the block 31 can achieve its function at about 5 millimeters, so its operation is fast and accurate. Under the working logic control of the vehicle control host, at the moment before the servo cylinder 23 drives the second connecting rod 22 to rotate, the electromagnetic cylinder 35 can separate the block 31 from the second connecting rod 22. At the same time, when implementing the locking operation, it is ensured that the second connecting rod 22 is in a state aligned with the block 31 (that is, the corresponding wheel is in a straight running state), so as to achieve the coordinated operation of the entire steering component 2.

[0063] This solution also includes a four-wheel steering control method, which is applied to the above four-wheel steering suspension system and includes:

[0064] The control host obtains the current vehicle driving speed value V and the front wheel steering angle A through vehicle functional components;

[0065] If the driving speed value V is greater than the first set value V1 and the front wheel steering angle value A is greater than the first set value A1, the controller deflects the rear wheels in the same direction as the front wheel steering angle direction, and the deflection angle of the rear wheel on the outer side of the turn is greater than the deflection angle of the rear vehicle on the inner side of the turn;

[0066] When the driving speed value V is less than the first set value V1 or the front wheel steering angle value A is less than the first set value A1;

[0067] The controller adjusts the left rear wheel and the right rear wheel to a straight running state and implements a locking operation on the left rear wheel and the right rear wheel.

[0068] Reference Figure 8 Figure 9, specifically, in this scenario, the vehicle is traveling at a relatively high speed, and rear-wheel steering is used to improve its lane-changing flexibility. The first set value V1 can be 70 kilometers per hour, and the first set value A1 can be ±8°. It should be noted that the first set value V1 and the first set value A1 can be a pair of combined values. In the trigger condition, the greater the speed, the smaller the steering angle. For the rear-wheel deflection, the greater the speed, the relatively smaller the deflection angle of the rear wheels;

[0069] In this method, by making the deflection angle of the rear wheel ( Figure 9 the right rear wheel in the middle) on the outer side of the turn slightly larger than the deflection angle of the rear wheel ( Figure 9 the left rear wheel in the middle) on the inner side of the turn, first, a certain internal binding force is generated through the difference in the deflection angles of the two rear wheels, thereby improving the stability of the vehicle and preventing oversteering. Second, a certain internal resistance is achieved through the right rear wheel, thereby preventing the tail of the vehicle from skidding outward, thus improving the stability and flexibility of the vehicle during driving.

[0070] If the driving speed value V is less than the second set value V2, and the front-wheel steering angle value A is greater than the second set value A2, the controller implements the deflection of the rear wheels in the direction opposite to the front-wheel steering angle direction, and makes the deflection angle of the rear wheel on the outer side of the turn greater than the deflection angle of the rear vehicle on the inner side of the turn.

[0071] Reference Figure 10 , specifically, in this scenario, the vehicle is traveling at a relatively low speed, and rear-wheel steering is used to reduce the turning radius and improve the flexibility of turning or cornering. The second set value V2 can be 30 kilometers per hour, and the second set value A2 can be ±15°. Simply put, in the case where the vehicle speed is slow and the turning direction is large; by making the deflection angle of the rear wheel ( Figure 10 the right rear wheel in the middle) on the outer side of the turn greater than the deflection angle of the rear wheel ( Figure 10 the left rear wheel in the middle) on the inner side of the turn, thus a certain internal resistance is achieved through the left rear wheel, thereby preventing the tail of the vehicle from skidding outward, thus improving the stability and flexibility of the vehicle during turning and cornering.

[0072] If the driving speed value V is negative, and the front-wheel steering angle value A is greater than the second set value A2, the controller implements the deflection of the rear wheels in the direction opposite to the front-wheel steering angle direction, and makes the deflection angle of the rear wheel on the outer side of the turn greater than the deflection angle of the rear vehicle on the inner side of the turn.

[0073] Specifically, in this scenario, the vehicle is reversing at a slow speed. This situation is similar to the previous scenario of slow cornering. When the vehicle is reversing or parking in reverse, the speed is slow and the turning direction is large. By making the deflection angle of the rear wheel on the outer side of the turn greater than the deflection angle of the rear wheel on the inner side of the turn, a certain internal resistance is achieved, thereby preventing the tail of the vehicle from skidding outward and improving the stability and flexibility of the vehicle during reverse operation.

[0074] A control method for stable vehicle driving, applied to the above four-wheel steering suspension system, includes:

[0075] The control host obtains the driving speed value V and the front-wheel steering angle A of the current vehicle through vehicle functional components;

[0076] The control host senses the rotational speed of the current four tires through the ABS sensors of the wheels;

[0077] When the rotational speed of the left front wheel or the right front wheel is significantly less than that of the other three wheels, and the driving speed value V is greater than the third set value V3, and the front-wheel steering angle value A is greater than the third set value A3, the controller deflects the rear wheels in the same direction as the front-wheel steering angle, and makes the deflection angle of the rear wheel on the outer side of the turn greater than the deflection angle of the rear vehicle on the inner side of the turn.

[0078] When the rotational speed of the left rear wheel or the right rear wheel is significantly less than that of the other three wheels, and the driving speed value V is greater than the third set value V3, the controller deflects the normal rear wheels in the same direction as the front wheels and performs a straight-line locking operation on the abnormal rear wheels.

[0079] When the rotational speed of the left rear wheel or the right rear wheel is significantly less than that of the other three wheels, and the driving speed value V is greater than the third set value V3, and the front-wheel steering angle value A is greater than the third set value A3, the controller deflects the normal rear wheels in the same direction as the front-wheel steering angle.

[0080] Specifically, in this scenario, when the vehicle is driving at a high speed, such as in the case of a tire blowout, the vehicle deflects due to the pulling of the blown-out tire, and the driver makes a reverse steering operation to correct the direction;

[0081] Through a large amount of data analysis by the inventor, due to the lack of corresponding experience, when a tire blows out, especially when the front tire blows out, because the vehicle deflects, most drivers will reverse-steer, and ultimately the vehicle will skid, collide or roll over in the direction of the reverse-steering. This method is used to deal with this situation to improve the stability of the vehicle;

[0082] Reference Figure 11 , when the right front wheel (Figure 11 a flat tire occurs in the red tire as shown), the first set value V3 can be 80 kilometers per hour, and the third set value A3 can be ±10°. By making the deflection angle of the rear wheel on the outer side of the turn ( Figure 11 the right rear wheel as shown) greater than that of the rear wheel on the inner side of the turn ( Figure 11 the left rear wheel as shown), first, a certain internal binding force is generated through the difference in the deflection angles of the two rear wheels, thereby improving the stability of the vehicle and preventing oversteering. Second, a certain internal resistance is achieved through the left rear wheel, thereby preventing the tail of the vehicle from sliding outward or even rolling over, etc., and thus the driving stability of the vehicle when a flat tire occurs can be improved.

[0083] Reference Figure 12 , when a flat tire occurs in the left rear wheel ( Figure 12 the red tire as shown), the first set value V3 can be 80 kilometers per hour, and the third set value A can be ±10°. By setting the rear wheel on the outer side of the turn ( Figure 12 the right rear wheel as shown), that is, the normal wheel, to deflect in the same direction as the front wheel, and performing a straight-line locking operation on the abnormal rear wheel, that is, Figure 12 the left rear wheel as shown, the occurrence of oversteering is prevented, thereby preventing the tail of the vehicle from sliding outward or even rolling over, etc., and thus the driving stability of the vehicle when a flat tire occurs can be improved.

[0084] So far, this solution provides differential rear-wheel steering control methods for multiple scenarios to improve the stability, controllability, and flexibility of the vehicle. It can be understood that the scenarios applied in this solution have wide adaptability and cannot be exemplified one by one. However, implementing differential steering control of the rear wheels through the vehicle control host will surely be more widely applied and provide a more stable and reliable experience for drivers or passengers.

[0085] In summary, the four-wheel steering suspension system of new energy vehicles in this solution is applied to new energy vehicles. Through electronic control and the vehicle host, the steering control of the four wheels, especially the rear wheels, can be implemented. Through the cooperation of the steering control of the front wheels and the rear wheels, high-speed fast lanes and low-speed low-turning-radius cornering can be achieved. This solution adopts an independent rear-wheel component structure, that is, the left and right rear wheels adopt completely independent steering components, and the steering components are completely arranged at the lower swing arm or lower link of the rear wheels. At the same time, a lightweight structure is adopted to reduce the unsprung mass. Compared with the traditional rear-wheel steering system with an integrated steering gear structure, it does not need to occupy the rear-wheel chassis space and can perform precise angle control on the left and right rear wheels separately, so as to realize the rear-wheel function in multiple scenarios in real time, greatly improving the driving functionality and stability of the vehicle;

[0086] The steering component of this solution is framed at the lower swing arm or lower link, without the need for large-scale re-design of the structure of existing vehicles. It is implemented through the driving mechanism of the first link, the second link, and the high-precision servo cylinder. The first link and the second link form a triangular stress structure for the frame, and the second link and the driving mechanism form a triangular stress structure for the frame, greatly improving the structural stability. The main body of the rotational force of the wheel is transmitted to the subframe through the structures of the first link and the second link, reducing the force distribution on the servo cylinder driving mechanism. With the configuration of large stroke and small angle, the accuracy of wheel rotation and the controllability of the servo cylinder driving mechanism are improved. At the same time, arranging the entire steering component at the lower swing arm or lower link can reduce the impact of the up and down shock movement of the vehicle's driving wheels on the steering system, resulting in less working interference and more stable operation;

[0087] A locking mechanism is arranged at the end of the second link of the steering component of this solution, which can perform locking operations when the rear wheels of the vehicle are in a straight state during normal driving. Therefore, the stability of vehicle operation is greatly improved, and the servo cylinder driving mechanism for controlling the rear-wheel steering can be in a standby state, reducing its working intensity and improving its service stability and service life;

[0088] A four-wheel steering control method of this solution realizes application functions in multiple scenarios by independently controlling the angles of the rear wheels. Especially by implementing different rear-wheel deflection angles for the two rear wheels, in the scenario of relatively high-speed driving of the vehicle, the tracking performance of the vehicle can be improved, and the occurrence of side slip, oversteering, or understeering can be reduced; when the vehicle is in scenarios such as low-speed turning or reverse parking, the driving stability of the vehicle can be improved, the turning radius can be reduced, and the convenience of turning and entering and leaving the parking space can be improved;

[0089] A vehicle stable driving control method of this solution mainly deals with situations such as abnormal wheels (such as flat tires) during high-speed driving of the vehicle. In this case, due to unilateral pulling, the driver of the vehicle is prone to oversteering in the opposite direction, resulting in vehicle out-of-control or rollover. This solution can reduce the phenomena of oversteering and rollover by implementing the operation of steering the rear wheels in the same direction as the front wheels, thus greatly improving the stability and controllability in extreme states;

[0090] By completely independently controlling and adjusting the rear wheels, this solution can perform differential and functional operations in multiple vehicle driving scenarios, which has excellent promotional significance and plays a positive role in the technology and application of new energy vehicles in China.

Claims

1. Four-wheel steering suspension system for new energy vehicles, characterized in that: Comprising: A front wheel assembly, including a left front wheel and a right front wheel, a suspension structure and a steering gear connecting the left front wheel and the right front wheel, and the steering gear connecting and controlling the rotation direction and angle of the left front wheel and the right front wheel; A rear wheel assembly, including a left rear wheel and a right rear wheel, a suspension structure connecting the left rear wheel and the right rear wheel, and steering components are arranged in the suspension structure, and the steering components are used to independently control the rotation direction and angle of the left rear wheel and the right rear wheel; A controller, according to the instruction of the vehicle control host, controls the steering components to implement independent control of the rotation direction and angle of the left rear wheel and the right rear wheel; A rotation angle sensor, arranged at the steering component, is used to obtain the current rotation angle value of the left rear wheel or the right rear wheel in real time, and feedback the rotation angle value to the vehicle control host; The steering component is arranged at the lower swing arm or lower link of the left rear wheel and the right rear wheel, one end is hinged to the steering seat through a ball head component, and the other end is hinged to the lower swing arm or lower link. A rotation driving mechanism is arranged at the hinge of the lower swing arm or lower link. The rotation driving mechanism is connected to the controller and drives the steering seat to rotate correspondingly through the steering component; The steering component includes a first link and a second link. The first link is connected to the steering arm of the steering seat through a first ball head. The other end of the first link is hinged to the second link. One end of the second link is connected to the lower swing arm or lower link through a second ball head, and a rotation driving mechanism is arranged on the second link; The second link extends outward at the hinge with the first link, and an articulated structure is arranged. A third ball head is arranged at the lower swing arm or lower link. A rotation driving mechanism is arranged between the third ball head and the articulated structure. The rotation driving mechanism is used to drive the second link and make it rotate around the second ball head, so that the steering component constructs a triangular force-bearing structure with the first link and the second link as the framework, and a triangular force-bearing structure with the second link and the rotation driving mechanism as the framework.

2. The four-wheel steering suspension system of the new energy vehicle according to claim 1, wherein: The first ball head is arranged at the lower rear position of the vehicle driving direction at the center point of the wheel.

3. The four-wheel steering suspension system of the new energy vehicle according to claim 1, wherein: The second ball head is arranged at a position close to the installation structure of the lower swing arm or lower link and the vehicle frame.

4. The four-wheel steering suspension system of the new energy vehicle according to claim 1, characterized in that: A locking mechanism is arranged at the front end of the second link, and the locking mechanism is used to limit the rotation of the second link and make the corresponding wheel in a straight driving state.

5. The four-wheel steering suspension system of the new energy vehicle according to claim 4, characterized in that: A V-shaped groove is arranged at the front end of the second link. The locking mechanism includes a block and a block driving mechanism. The front end of the block is provided with a V-shaped protrusion, and the front end of the V-shaped protrusion can be embedded in the V-shaped groove arranged therein.

6. A four-wheel steering control method is applied to the four-wheel steering suspension system according to any one of claims 1 to 5, characterized in that: Comprising: The control host obtains the current vehicle driving speed value V and the front wheel steering angle A through vehicle functional components; If the driving speed value V is greater than the first set value V1, and the front wheel steering angle value A is greater than the first set value A1, the controller deflects the rear wheels in the same direction as the front wheel steering angle direction, and the deflection angle of the rear wheel on the outer side of the turn is greater than the deflection angle of the rear wheel on the inner side of the turn; If the driving speed value V is less than the second set value V2 and the front wheel steering angle value A is greater than the second set value A2, the controller deflects the rear wheels in a direction opposite to the front wheel steering angle, and the deflection angle of the rear wheel on the outer side of the turn is greater than that of the rear vehicle on the inner side of the turn; If the driving speed value V is negative and the front wheel steering angle value A is greater than the second set value A2, the controller deflects the rear wheels in a direction opposite to the front wheel steering angle, and the deflection angle of the rear wheel on the outer side of the turn is greater than that of the rear vehicle on the inner side of the turn.

7. A control method for stable vehicle driving, which is applied to the four-wheel steering suspension system according to any one of claims 1 to 5, characterized in that: Including: The control host obtains the driving speed value V of the current vehicle and the front wheel steering angle A through vehicle functional components; The control host obtains the rotation speed conditions of the current four tires through the ABS sensing components of the wheels; When the rotation speed of the left front wheel or the right front wheel is significantly less than that of the other three wheels, and the driving speed value V is greater than the third set value V3, and the front wheel steering angle value A is greater than the third set value A3, the controller deflects the rear wheels in the same direction as the front wheel steering angle; When the rotation speed of the left rear wheel or the right rear wheel is significantly less than that of the other three wheels, and the driving speed value V is greater than the third set value V3, the controller deflects the normal rear wheels in the same direction as the front wheels and performs a straight-line locking operation on the abnormal rear wheels.

8. A control method for stable vehicle driving according to claim 7, characterized in that: When the rotation speed of the left rear wheel or the right rear wheel is significantly less than that of the other three wheels, and the driving speed value V is greater than the third set value V3, and the front wheel steering angle value A is greater than the third set value A3, the controller deflects the normal rear wheels in the same direction as the front wheel steering angle.

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