A steering assist system based on vehicle multi-link rear suspension system

Abstract

The present invention provides a steering assist system based on a multi-link rear suspension system of a vehicle: the system comprises a steering link and a lifting mechanism; the first end of the steering link is movably connected to the rear wheel of the vehicle, and the second end of the steering link is connected to the lifting mechanism; the lifting mechanism is fixedly connected to the vehicle frame and is used to lift or lower the second end of the steering link; in an initial state, an extension line of the steering link, an extension line of an upper suspension swing arm of the vehicle and an extension line of a lower suspension swing arm of the vehicle intersect at one point, and the multi-link rear suspension system is in a geometric equilibrium state at this time, and the rear wheel toe angle will not be changed when the vehicle turns; when the lifting mechanism lifts or lowers the second end of the steering link so that the extension line of the steering link, the extension line of the upper suspension swing arm of the vehicle and the extension line of the lower suspension swing arm of the vehicle no longer intersect at one point, the geometric equilibrium state of the multi-link rear suspension system is destroyed, and the rear wheel toe angle will be changed due to the suspension displacement caused by the center of gravity transfer when the vehicle turns.

Description

Technical Field

[0001] The invention relates to a multi-link rear suspension system, in particular to a steering assist system based on the multi-link rear suspension system of a vehicle. Background Art

[0002] When a vehicle is turning at high speed, the center of gravity shifts, and different rear wheel toe angles will greatly affect the vehicle's cornering performance. At the same time, different rear wheel toe angles will also affect the vehicle's performance when driving in a straight line. For example, when the rear wheel toe angle is slightly inward, the vehicle's stability can be increased when turning at high speed. However, when the rear wheel toe angle is slightly inward, tire friction will form resistance to forward driving and accelerate tire wear. Therefore, when designing the rear suspension of the vehicle, it is necessary to find an appropriate value to try to meet the performance of both turning and straight driving.

[0003] Some multi-link rear suspension systems use the difference in link lengths to allow the rear wheels to use the body roll during cornering to increase the toe angle of the outer rear wheels. However, since this method of changing the rear wheel toe angle by relying on suspension geometry is based on the compression of the suspension springs, in addition to the rear wheel toe angle changing due to the body roll during cornering, the rear wheel toe angle will also change due to the compression of the suspension springs when passing uneven roads, or when braking, or when accelerating. However, the change in the rear wheel toe angle in these cases is usually not conducive to the vehicle's driving performance.

[0004] In recent years, passenger cars have gradually adopted rear-wheel steering technology to improve the maneuverability of the vehicle during low-speed parking, high-speed straight-line driving performance, and vehicle stability during high-speed cornering. The rear-wheel steering system can adjust the rear wheel angle in real time, allowing the vehicle to take into account both cornering and straight-line performance. The existing rear-wheel steering system mainly has a steering machine similar to the front-wheel steering to achieve lateral stretching of the connecting rod that controls the direction in the multi-link rear suspension system. Since it is on the rear wheel, this device for lateral stretching of the connecting rod is usually electrically driven, which can achieve synchronous control of the two rear wheels, or independent control of the rear wheels. The device that synchronously controls the two rear wheels can only achieve rear-wheel steering. The device for independently controlling the rear wheels can realize rear wheel steering and arbitrary change of the rear wheel toe angle. However, this method of changing the rear wheel toe angle by lateral stretching of the connecting rod has limitations. First, since the rear wheel is turned directly by stretching the connecting rod, a relatively large force is required to complete it. At the same time, the vehicle switches from straight driving to turning in a very short time, which means that the electronic servo device used to drive the rear wheel steering needs to have a relatively large power; secondly, since the rear wheel steering is completed by directly pulling the connecting rod by the electronic servo device, the failure of the electronic servo device will bring great safety hazards to the entire vehicle, especially when driving at high speeds. Once the electronic servo device makes an error, it is easy to cause steering at the wrong time, which will cause the entire vehicle to lose control or even roll over. Summary of the invention

[0005] The technical problem to be solved by the present invention is to overcome the defects of the above-mentioned prior art and provide a steering assist system based on a vehicle multi-link rear suspension system which has a simple structure, does not require a high-power servo device, and has a low safety hazard to the vehicle when a failure occurs.

[0006] The technical solution of the present invention is to provide a steering assist system based on a vehicle multi-link rear suspension system having the following structure: the system is symmetrically arranged on the inner sides of the two rear wheels of the vehicle, and comprises a steering link and a lifting mechanism; the first end of the steering link is movably connected to the rear wheel of the vehicle, and the second end of the steering link is connected to the lifting mechanism; the lifting mechanism is fixedly connected to the vehicle frame and is used to lift or lower the second end of the steering link;

[0007] In the initial state, the extension line of the steering link, the extension line of the upper suspension arm of the vehicle and the extension line of the lower suspension arm of the vehicle intersect at one point. At this time, the multi-link rear suspension system is in a geometric equilibrium state, and the rear wheel toe angle will not change when the vehicle turns. When the lifting mechanism lifts or lowers the second end of the steering link so that the extension line of the steering link, the extension line of the upper suspension arm of the vehicle and the extension line of the lower suspension arm of the vehicle no longer intersect at one point, the geometric equilibrium state of the multi-link rear suspension system is destroyed, and when the vehicle turns, the rear wheel toe angle will change due to the suspension displacement caused by the transfer of the center of gravity.

[0008] Preferably, the lifting mechanism comprises a lever, a connecting frame and a tie rod servo; the central fixed point of rotation of the lever is connected to the frame through the connecting frame, one end of the lever is hinged to the second end of the steering link, and the other end of the lever is connected to the tie rod servo, and the tie rod servo is used to drive the lever to rotate around the central fixed point.

[0009] Preferably, the lever comprises a first connecting arm and a second connecting arm, and the central fixed point of rotation of the lever is located at the connection between the first connecting arm and the second connecting arm; the length dimension of the first connecting arm is smaller than the length dimension of the second connecting arm.

[0010] Preferably, the connecting frame is provided with a positioning pin, and the lever is provided with a positioning groove matched with the positioning pin; when the positioning pin is located in the positioning groove, the vehicle multi-link rear suspension system is in a geometric equilibrium state. With this arrangement, the tie rod servo can accurately pull the second end of the steering link back to the initial state position after the vehicle turns; the positioning pin is not a necessary component, and positioning can also be performed by the stop position of the tie rod servo.

[0011] Preferably, the tie rod servo may be a drive motor, a drive cylinder or a mechanical drive directly driven by a driver.

[0012] After adopting the above structure, the steering assist system based on the vehicle multi-link rear suspension system of the present invention has the following advantages:

[0013] 1. During normal driving, the multi-link rear suspension system of the vehicle is in a geometric equilibrium state. Even when driving on uneven roads, braking, or accelerating, the rear wheel toe angle will not change, thereby ensuring the vehicle's straight-line driving performance; when steering is required, the tie rod servo is activated to change the position of the second end of the steering link, thereby breaking the geometric equilibrium state of the multi-link rear suspension system, causing the rear wheel toe angle to change due to the compression of the suspension spring by the center of gravity shift when the vehicle is turning, thereby ensuring the stability of the vehicle when turning. Since the rear wheel toe angle is not changed directly by stretching the steering link, but by changing the position of the second end of the steering link to break the geometric equilibrium state of the multi-link rear suspension system, causing the rear wheel toe angle to change due to the compression of the suspension spring by the center of gravity shift when the vehicle is turning, the moving distance and force required for the tie rod servo are greatly reduced, which can reduce the power of the tie rod servo, reduce costs, and reduce accidents.

[0014] 2. The drastic change in the rear wheel camber angle does not come entirely from the action of the tie rod servo on the steering linkage (moving the other end of the steering linkage can slightly change the rear wheel camber angle), but is based on changes in the suspension geometry. When the vehicle turns, the center of gravity shifts and the suspension springs are compressed, which changes the rear wheel camber angle. Therefore, even if the system fails when the vehicle is driving at high speed, as long as the road surface is relatively flat (such as a highway), there is a great chance that the vehicle will stop safely, which greatly reduces the safety hazard to the vehicle when the system fails.

[0015] 3. After the tie rod servo changes the suspension geometry, the rear wheel camber angle will increase with the increase of body roll. The greater the body roll, the more intense the vehicle's cornering, which just meets the vehicle's need for additional camber.

[0016] 4. The change of the position of the second end of the steering link does not require computer control, and a simple switch can achieve functionality. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural schematic diagram of the present invention.

[0018] Figure 2 It is a schematic diagram of the local structure of the present invention.

[0019] Figure 3 It is a schematic structural diagram of the lever of the present invention.

[0020] As shown in the figure:

[0021] 1. Steering link, 2. Lifting mechanism, 3. Lever, 4. Connecting frame, 5. Tie rod servo, 6. First connecting arm, 7. Second connecting arm, 8. Locating pin, 9. Locating groove, 10. Upper suspension swing arm, 11. Lower suspension swing arm. DETAILED DESCRIPTION

[0022] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] In the description of the present invention, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as a limitation on the present invention. At the same time, the terms "first", "second", etc. are only used to distinguish the names of the components, and there is no primary or secondary relationship, and therefore cannot be understood as a limitation on the present invention.

[0024] like Figure 1 , Figure 2 and Figure 3 As shown;

[0025] The present invention discloses a steering assist system based on a vehicle multi-link rear suspension system having the following structure: the system is symmetrically arranged at the inner rear end of two rear wheels of the vehicle, and comprises a steering link 1 and a lifting mechanism 2; the first end of the steering link 1 is movably connected to the rear wheel of the vehicle, and the second end of the steering link 1 is connected to the lifting mechanism 2; the lifting mechanism 2 is fixedly connected to the vehicle frame, and is used to lift or lower the second end of the steering link 1; the lifting mechanism 2 comprises a lever 3, a connecting frame 4 and a pull rod servo 5; the central fixed point of rotation of the lever 3 is connected to the vehicle frame through the connecting frame 4, one end of the lever 3 is hinged to the second end of the steering link 1, and the other end of the lever 3 is connected to the pull rod servo 5, and the pull rod servo 5 is used to drive the lever 3 to rotate around the central fixed point; the lever 3 comprises a first connecting arm 6 and a second connecting arm 7, the central fixed point of rotation of the lever 3 is located at the connection between the first connecting arm 6 and the second connecting arm 7, and a concave cavity is formed between the steering link 1 and the first connecting arm 6; the length dimension of the first connecting arm 6 is smaller than the length dimension of the second connecting arm 7, and after such arrangement, the power required by the pull rod servo 5 can be further reduced by utilizing the principle of the lever 3;

[0026] In the initial state, the extension line of the steering link 1, the extension line of the upper suspension arm 10 of the vehicle and the extension line of the lower suspension arm 11 of the vehicle intersect at one point. At this time, the multi-link rear suspension system is in a geometric equilibrium state. Even when passing over uneven roads, braking, or accelerating, the rear wheel toe angle will not change, thereby ensuring the vehicle's straight-line driving performance.

[0027] When the vehicle is turning at high speed, if the opening of the concave cavity formed between the steering link 1 and the first connecting arm 6 faces upward, the second end of the steering link 1 is lifted by the tie rod servo 5 and the lever 3, and the steering link 1 slightly pushes the rear wheel to make the rear wheel camber slightly inward. At the same time, since the geometric balance state of the vehicle's multi-link rear suspension system is destroyed, the suspension spring is compressed due to the center of gravity shift when the vehicle is turning, and the rear wheel camber is further increased, thereby ensuring the stability of the vehicle when turning; after the tie rod servo 5 changes the suspension geometry, the rear wheel camber angle will increase with the increase of the body roll. The greater the body roll, the more intense the vehicle's cornering will be, which just meets the vehicle's need for additional camber. The height to which the steering link 1 is lifted cannot exceed the highest point to prevent the vehicle body from swaying and causing rollover (at the highest point, the steering link 1 and the first connecting arm 6 are located on the same straight line); if the concave cavity formed between the steering link 1 and the first connecting arm 6 is open downward, the second end of the steering link 1 is lowered through the pull rod servo 5 and the lever 3, and the steering link 1 cannot be lowered beyond the lowest point (at the lowest point, the steering link 1 and the first connecting arm 6 are located on the same straight line).

[0028] When the vehicle turns at a low speed, if the opening of the concave cavity formed between the steering link 1 and the first connecting arm 6 faces upward, the second end of the steering link 1 can be lowered by the pull rod servo 5 and the lever 3 to make the rear wheel toe angle slightly outward to reduce the turning radius of the vehicle; if the opening of the concave cavity formed between the steering link 1 and the first connecting arm 6 faces downward, the second end of the steering link 1 can be lifted by the pull rod servo 5 and the lever 3 to make the rear wheel toe angle slightly outward to reduce the turning radius of the vehicle.

[0029] The same principle as above, if the steering assist system based on the vehicle multi-link rear suspension system is symmetrically arranged at the inner front end of the two rear wheels of the vehicle, when the vehicle is turning at high speed, if the opening of the concave formed between the steering link 1 and the first connecting arm 6 faces upward, the second end of the steering link 1 is lowered by the tie rod servo 5 and the lever 3 to make the rear wheel toe angle slightly inward eight; if the opening of the concave formed between the steering link 1 and the first connecting arm 6 faces downward, the second end of the steering link 1 is lifted by the tie rod servo 5 and the lever 3 to make the rear wheel toe angle slightly inward eight, so as to ensure the stability of the vehicle when turning. When the vehicle is turning at low speed, if the opening of the concave formed between the steering link 1 and the first connecting arm 6 faces upward, the second end of the steering link 1 can be lifted by the tie rod servo 5 and the lever 3 to make the rear wheel toe angle slightly outward eight, so as to reduce the turning radius of the vehicle; if the opening of the concave formed between the steering link 1 and the first connecting arm 6 faces downward, the second end of the steering link 1 can be lowered by the tie rod servo 5 and the lever 3 to make the rear wheel toe angle slightly outward eight.

[0030] Since the rear wheel toe angle is not changed directly by stretching the steering link 1, but by changing the position of the second end of the steering link 1 to break the geometric equilibrium state of the multi-link rear suspension system, so that the rear wheel toe angle is changed due to the compression of the suspension spring by the center of gravity offset when the vehicle is turning, the moving distance of the tie rod servo 5 and the force required for movement are greatly reduced, which can reduce the power of the tie rod servo 5, reduce costs, and reduce accidents. In addition, since the large change in the rear wheel toe angle is not entirely due to the effect of the tie rod servo 5 on the steering link 1 (moving the other end of the steering link 1 can slightly change the rear wheel toe angle), but on this basis, the suspension geometry is changed, so that the rear wheel toe angle is changed due to the compression of the suspension spring by the center of gravity offset of the vehicle when the vehicle is turning, even if the system fails when the vehicle is driving at high speed, it will not cause safety hazards to the vehicle.

[0031] The tie rod servo 5 may be a drive motor, a drive cylinder, or a mechanical drive directly driven by a driver.

[0032] The connecting frame 4 is provided with a positioning pin 8, and the lever 3 is provided with a positioning groove 9 adapted to the positioning pin 8; when the positioning pin 8 is located in the positioning groove, the vehicle multi-link rear suspension system is in a geometrically balanced state, so that the tie rod servo 5 can accurately pull the second end of the steering link 1 back to the initial state position after the vehicle turns. The positioning pin 8 is not a necessary component and can also be positioned by the stop position of the tie rod servo 5.

[0033] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A steering assist system based on a vehicle multi-link rear suspension system, which is symmetrically arranged on the inner sides of two rear wheels of the vehicle, characterized in that: The vehicle comprises a steering link (1) and a lifting mechanism (2); the first end of the steering link (1) is movably connected to the rear wheel of the vehicle, and the second end of the steering link (1) is connected to the lifting mechanism (2); the lifting mechanism (2) is fixedly connected to the vehicle frame and is used to lift or lower the second end of the steering link (1); In the initial state, the extension line of the steering link (1), the extension line of the upper suspension arm (10) of the vehicle, and the extension line of the lower suspension arm (11) of the vehicle intersect at one point. At this time, the multi-link rear suspension system is in a geometric equilibrium state, and the rear wheel toe angle will not change when the vehicle turns. When the lifting mechanism (2) lifts or lowers the second end of the steering link (1) so that the extension line of the steering link (1), the extension line of the upper suspension arm (10) of the vehicle, and the extension line of the lower suspension arm (11) of the vehicle no longer intersect at one point, the geometric equilibrium state of the multi-link rear suspension system is destroyed, and when the vehicle turns, the rear wheel toe angle will change due to the suspension displacement caused by the center of gravity transfer. During normal driving, the vehicle's multi-link rear suspension system is in a geometrically balanced state. Even when driving on uneven roads, braking, or accelerating, the rear wheel toe angle will not change, thus ensuring the vehicle's straight-line driving performance. When steering is required, the pull rod servo is activated to change the position of the second end of the steering link, thereby breaking the geometric balance state of the multi-link rear suspension system, causing the suspension spring to be compressed due to the center of gravity shift when the vehicle is turning, thereby ensuring the stability of the vehicle when turning; the rear wheel toe angle is not changed directly by stretching the steering link, but by changing the position of the second end of the steering link to break the geometric balance state of the multi-link rear suspension system, causing the suspension spring to be compressed due to the center of gravity shift when the vehicle is turning; The lifting mechanism (2) comprises a lever (3), a connecting frame (4) and a tie rod servo (5); the central fixed point of rotation of the lever (3) is connected to the vehicle frame via the connecting frame (4); one end of the lever (3) is hinged to the second end of the steering link (1); the other end of the lever (3) is connected to the tie rod servo (5); and the tie rod servo (5) is used to drive the lever (3) to rotate around the central fixed point; The connecting frame (4) is provided with a positioning pin (8), and the lever (3) is provided with a positioning groove (9) matched with the positioning pin (8); when the positioning pin (8) is located in the positioning groove, the vehicle multi-link rear suspension system is in a geometrically balanced state.

2. A steering assist system based on a vehicle multi-link rear suspension system according to claim 1, characterized in that: The lever (3) comprises a first connecting arm (6) and a second connecting arm (7); the central fixed point of rotation of the lever (3) is located at the connection between the first connecting arm (6) and the second connecting arm (7); the length of the first connecting arm (6) is smaller than the length of the second connecting arm (7).

3. The steering assist system based on a vehicle multi-link rear suspension system according to claim 1, characterized in that: The tie rod servo (5) may be a drive motor, a drive cylinder, or a mechanical drive directly driven by a driver.

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