阅读说明：本技术 一种车辆前束自动调节装置及车辆前束自动调节方法 (Automatic adjusting device and method for vehicle toe-in ) 是由 汪洪波 史根木 米向东 张惠迪 韩涛 花千禧 许宇航 冯立钊 于 2021-07-05 设计创作，主要内容包括：本发明涉及一种车辆前束自动调节装置及车辆前束自动调节方法。所述装置包括分别安装在车辆的转向器中齿条的相对两端上的两个调节机构,两个调节机构分别用于在车辆行驶过程中实现车辆的前束调节。每个调节机构包括横拉杆接头、前束调节接头、主动轮、电机、位移传感器、控制器。前束调节接头包括接头杆、从动轮、齿轮轴、深沟球轴承、推力球轴承。位移传感器实时检测齿轮轴裸露在转向器中齿条外的伸长量,控制器判定伸长量是否在一个预设的伸长量范围内,如果不在则驱动电机使伸长量在预设的伸长量范围内,实现车辆的前束调节。本发明具有体积较小、结构简单、成本低等特点,具有易检查和排除问题所在的优势。(The invention relates to an automatic adjusting device and an automatic adjusting method for vehicle toe-in. The device comprises two adjusting mechanisms which are respectively arranged at two opposite ends of a rack in a steering gear of the vehicle, and the two adjusting mechanisms are respectively used for realizing toe-in adjustment of the vehicle in the running process of the vehicle. Each adjusting mechanism comprises a tie rod joint, a toe-in adjusting joint, a driving wheel, a motor, a displacement sensor and a controller. The toe-in adjusting joint comprises a joint rod, a driven wheel, a gear shaft, a deep groove ball bearing and a thrust ball bearing. The displacement sensor detects the elongation of the gear shaft exposed outside the rack in the steering gear in real time, the controller judges whether the elongation is within a preset elongation range, and if not, the drive motor drives the elongation to be within the preset elongation range, so that toe-in adjustment of the vehicle is realized. The invention has the characteristics of small volume, simple structure, low cost and the like, and has the advantage of easy inspection and problem elimination.)

1. An automatic adjusting device for a vehicle toe-in comprises two adjusting mechanisms which are respectively arranged at two opposite ends of a rack (1) in a steering gear of the vehicle, wherein the two adjusting mechanisms are respectively used for adjusting the relative lengths of a left transverse pull rod and a right transverse pull rod of the vehicle relative to a left wheel and a right wheel of the vehicle in the running process of the vehicle so as to realize the toe-in adjustment of the vehicle, and the automatic adjusting device is characterized in that:

each adjustment mechanism includes:

the tie rod joints (4) are fixed on the corresponding tie rods;

toe-in adjustment joint, comprising: the device comprises a joint rod (8), a driven wheel (9), a gear shaft (2), a deep groove ball bearing (10) and a thrust ball bearing (11); one end of the joint rod (8) is in transmission connection with the driven wheel (9) through a thrust ball bearing (11), and the other opposite end of the joint rod (8) is fixed on the tie rod joint (4); one end of a gear shaft (2) is in transmission connection with a driven wheel (9) through a deep groove ball bearing (10), the other opposite end of the gear shaft (2) is inserted into the end face of the corresponding end of a rack (1) in a steering gear in a threaded connection mode, and centers of a tie rod joint (4), a joint rod (8), the driven wheel (9), the gear shaft (2) and the rack (1) in the steering gear are all located on the same straight line; the extension amount of a gear shaft (2) exposed outside a rack (1) in the steering gear is changed under the assistance of a deep groove ball bearing (10) through the rotation of a driven wheel (9), and a tie rod joint (4) is pushed or pulled under the assistance of a thrust ball bearing (11), so that the synchronous adjustment of a corresponding tie rod and the corresponding extension amount is realized;

the driving wheel (6) is meshed with the driven wheel (9);

the motor (5) drives the driving wheel (6) to rotate;

the displacement sensor detects the elongation in real time, and the elongation represents the relative length of the corresponding tie rod;

and the controller is used for judging whether the elongation is within a preset elongation range or not, and if not, driving the motor (5) to rotate the driving wheel (6) to enable the driving wheel (6) to drive the driven wheel (9) to rotate, so that the elongation is adjusted to enable the elongation to be within the preset elongation range, and the toe-in adjustment of the vehicle is realized.

2. The automatic vehicle toe adjustment device according to claim 1, wherein each adjustment mechanism further comprises a first housing (3); the driven wheel (9) is accommodated in the first shell (3), and part of gears of the driven wheel (9) are exposed out of the first shell (3) to be meshed with the driving wheel (6); the joint rod (8) and the gear shaft (2) are connected with the driven wheel (9) by extending into the first shell (3).

3. The automatic adjusting device for the toe-in of a vehicle according to claim 2, wherein a window (31) is formed on one side of the first shell (3), and two through holes (32) are formed in the first shell (3) and located on two opposite sides of the window (31); one end of the joint rod (8) is in transmission connection with the driven wheel (9) through one of the through holes (32), and the other opposite end of the joint rod (8) is fixed on the tie rod joint (4); one end of the gear shaft (2) is in transmission connection with the driven wheel (9) through another through hole (32), and part of gears of the driven wheel (9) are exposed outside the first shell (3) through the window (31) to be meshed with the driving wheel (6).

4. The automatic adjusting device for vehicle toe-in according to claim 3, wherein the first housing (3) comprises a first cover body (33) and a second cover body (34) which are mutually covered, two through holes (32) are respectively formed on the first cover body (33) and the second cover body (34), and the window (31) is formed at the joint of the first cover body (33) and the second cover body (34).

5. The automatic vehicle toe adjustment device according to claim 4, wherein the first cover body (33) and the second cover body (34) are in a shape like a Chinese character 'ji', the protruding parts of the first cover body (33) and the second cover body (34) are opposite to form a containing space for containing the driven wheel (9), and two ends of the first cover body (33) are respectively fixed with two ends of the second cover body (34).

6. The automatic vehicle toe adjustment device according to claim 4, wherein the first cover (33) and the second cover (34) are fixed by a plurality of screws (12).

7. The automatic vehicle toe adjustment device according to claim 2, wherein each adjustment mechanism further comprises a second housing (13), and the second housing (13) accommodates the first housing (3) and the driving wheel (6).

8. A vehicle toe-in automatic adjustment method is characterized by comprising the following steps:

the method comprises the following steps of firstly, installing the automatic vehicle toe-in adjusting device according to any one of claims 1 to 7 on a vehicle;

secondly, acquiring the elongation of a gear shaft (2) of the automatic vehicle toe-in adjusting device, which is exposed outside a rack (1) in a steering gear;

step three, judging whether the elongation is within a preset elongation range;

and step four, if the elongation is not in the preset elongation range, driving a motor (5) of the automatic vehicle toe-in adjusting device so as to adjust the elongation, so that the elongation is in the preset elongation range, and adjusting the toe-in of the vehicle.

9. A vehicle, comprising:

two wheels;

a rack bar (1) in the steering gear for assisting the steering of the two wheels;

two tie rods arranged at two opposite ends of a rack (1) in the steering gear;

the automatic vehicle toe-in adjusting device is used for adjusting the relative lengths of the two tie rods relative to the two wheels so as to realize toe-in adjustment of the vehicle;

the method is characterized in that: the automatic vehicle toe adjustment device according to any one of claims 1 to 7.

10. The vehicle according to claim 9, characterized in that the end surfaces of the opposite ends of the rack (1) in the steering gear are respectively provided with two screw holes for being respectively in threaded connection with the two gear shafts (2).

Technical Field

The invention relates to the field of automobile steering systems, in particular to an automatic vehicle toe-in adjusting device, an automatic vehicle toe-in adjusting method and a vehicle provided with the automatic vehicle toe-in adjusting device.

Background

When the automobile wheel is positioned, in order to prevent the tire from sliding relative to the ground during the running process of the automobile due to the existence of the camber angle, the additional abrasion of the tire is caused. The front ends of the left and right wheels are typically tilted inward or outward by the same angle, which is referred to as toe-in. If the front ends of the left and right wheels tilt inwards, the front end is called a positive toe-in, as shown in FIG. 1; if the front ends of the left and right wheels are tilted outward, it is called a negative toe-in, as shown in fig. 2.

The toe-in has a large relationship with the running deviation of the vehicle and the wear of the tires during running. Especially, in the process of turning the vehicle, the lateral force applied to the inner wheel and the outer wheel is different, and the load is transferred. At this time, the influence of the same toe-in angle of the left and right wheels on the steering cannot be offset, and the change of the yaw rate and the lateral acceleration of the whole vehicle can be influenced, so that the steering stability of the whole vehicle is influenced. At present, the toe-in is basically adjusted by adjusting the length of the steering tie-rod when the vehicle is stationary. However, the traditional adjusting mode is time-consuming, labor-consuming and troublesome, and the accuracy of toe-in adjustment is not high; on the other hand, the toe-in has a large influence on the operation stability during the dynamic driving of the vehicle, so the optimal toe-in adjustment mode is not adjustment in a stationary state, but the size of the toe-in is adjusted in real time during the driving of the vehicle according to the information such as the speed and the road condition of the vehicle during the driving.

The invention patent application CN104290814A discloses a hydraulic steering wheel toe-in value adjusting mechanism. The mechanism has ingenious design and novel design. In the running process of the vehicle, the length of the tie rod is adjusted through a hydraulic mechanism such as a servo electro-hydraulic cylinder and the like, and then the toe-in of the vehicle is adjusted. And the electro-hydraulic servo cylinder in the device is provided with an MR displacement sensor, so that the length of the transverse pull rod can be accurately controlled, and the accuracy of toe-in adjustment is improved. However, when the hydraulic mechanism is in failure, the hydraulic mechanism is not easy to check and eliminate. Especially when oil leakage occurs, it may cause inconvenience in maintenance and use of the apparatus.

Disclosure of Invention

In view of the above, the present invention is directed to a vehicle toe-in automatic adjusting device, a vehicle toe-in automatic adjusting method, and a vehicle having the vehicle toe-in automatic adjusting device, which are used to solve the technical problem that the conventional vehicle is not easy to check and eliminate when a hydraulic mechanism fails.

The invention adopts the following technology to realize, a vehicle toe-in automatic regulating device comprises two regulating mechanisms which are respectively arranged on the two opposite ends of a rack in a steering gear of a vehicle, the two regulating mechanisms are respectively used for regulating the relative lengths of a left transverse pull rod and a right transverse pull rod of the vehicle relative to a left wheel and a right wheel of the vehicle in the running process of the vehicle so as to realize the toe-in regulation of the vehicle, and each regulating mechanism comprises:

the tie rod joints are fixed on the corresponding tie rods;

toe-in adjustment joint, comprising: the joint rod, the driven wheel, the gear shaft, the deep groove ball bearing and the thrust ball bearing; one end of the joint rod is in transmission connection with the driven wheel through a thrust ball bearing, and the other opposite end of the joint rod is fixed on the tie rod joint; one end of the gear shaft is in transmission connection with the driven wheel through a deep groove ball bearing, the other opposite end of the gear shaft is inserted into the end face of the corresponding end of the rack in the steering gear in a threaded connection mode, and the centers of the tie rod joint, the joint rod, the driven wheel, the gear shaft and the rack in the steering gear are all positioned on the same straight line; the extension amount of a gear shaft exposed outside a rack in the steering gear is changed under the assistance of a deep groove ball bearing through the rotation of a driven wheel, and a tie rod joint is pushed or pulled under the assistance of a thrust ball bearing, so that the synchronous adjustment of a corresponding tie rod and the corresponding extension amount is realized;

the driving wheel is meshed with the driven wheel;

the motor drives the driving wheel to rotate;

the displacement sensor detects the elongation in real time, and the elongation represents the relative length of the corresponding tie rod;

the controller judges whether the elongation is within a preset elongation range or not, and if not, the driving wheel is driven by the driving motor to rotate, so that the driving wheel drives the driven wheel to rotate, the elongation is adjusted, the elongation is within the preset elongation range, and toe-in adjustment of the vehicle is realized.

As a further improvement of the above solution, each adjusting mechanism further comprises a first housing; the driven wheel is accommodated in the first shell, and part of gears of the driven wheel are exposed outside the first shell so as to be meshed with the driving wheel; the joint rod and the gear shaft are connected with the driven wheel by extending into the first shell.

Furthermore, a window is formed in one side of the first shell, and two through holes which are oppositely arranged are formed in the first shell and are respectively positioned on two opposite sides of the window; one end of the joint rod is in transmission connection with the driven wheel through one of the through holes, and the other opposite end of the joint rod is fixed on the tie rod joint; one end of the gear shaft is in transmission connection with the driven wheel through another through hole, and part of gears of the driven wheel are exposed outside the first shell through the window to be meshed with the driving wheel.

Furthermore, the first shell comprises a first cover body and a second cover body which are mutually covered, the two through holes are respectively formed in the first cover body and the second cover body, and the window is formed in the joint of the first cover body and the second cover body.

Furthermore, the first cover body and the second cover body are in a shape like a Chinese character 'ji', the protruding parts of the first cover body and the second cover body are opposite to form a containing space for containing the driven wheel, and two ends of the first cover body are respectively fixed with two ends of the second cover body.

Furthermore, the first cover body and the second cover body are fixed through a plurality of screws.

Still further, each adjusting mechanism further comprises a second shell, and the second shell accommodates the first shell and the driving wheel.

The invention also provides a vehicle toe-in automatic adjusting method, which comprises the following steps:

step one, installing the automatic adjusting device for the toe-in of any vehicle on the vehicle;

secondly, acquiring the elongation of a gear shaft of the automatic vehicle toe-in adjusting device, which is exposed outside a rack in a steering gear;

step three, judging whether the elongation is within a preset elongation range;

and step four, if the elongation is not in the preset elongation range, driving a motor of the automatic vehicle toe-in adjusting device so as to adjust the elongation, so that the elongation is in the preset elongation range, and adjusting the toe-in of the vehicle.

The present invention also provides a vehicle, comprising:

two wheels;

a rack in a steering gear for assisting the steering of the two wheels;

two tie rods mounted on opposite ends of a rack in a steering gear;

the automatic vehicle toe-in adjusting device is used for adjusting the relative lengths of the two tie rods relative to the two wheels so as to realize toe-in adjustment of the vehicle;

wherein: the automatic vehicle toe-in adjusting device is any of the automatic vehicle toe-in adjusting devices.

As a further improvement of the scheme, two screw holes which are respectively in threaded connection with two gear shafts are respectively formed in the end faces of two opposite ends of the rack in the steering gear.

The invention has the characteristics of small volume, simple structure, low cost and the like. The automatic adjusting device for the toe-in of the vehicle can pull the cross pull rod to further pull the wheel to rotate around the main pin. This is also one of the principles of a steering system to effect steering of a vehicle, such as a racing car. Therefore, if the toe adjustment joint of the device has enough telescopic stroke, the device can also independently realize the steering function of the racing car and realize the unmanned steering of the racing car, and in addition, the existence of the automatic toe adjustment device of the vehicle cannot influence the driving of a driver, thereby providing a new idea for the design of the steering system of the university student unmanned formula racing car.

When the steering wheel is used as an unmanned steering system, independent steering of the left wheel and the right wheel of the front axle of the racing car can be realized. For the steering system of the unmanned vehicle, the optimal steering effect is as follows: when the racing car passes through a curve, the decision-making mechanism calculates the most appropriate inner and outer wheel turning angles according to information such as road conditions and speed, considering characteristics such as tire cornering and principles such as ackermann steering geometry of the racing car, and then the control system of the racing car controls an unmanned steering system of the racing car to execute the steering. In the conventional integral steering, the steering angle of the left wheel and the right wheel can hardly reach the target angle simultaneously due to the mechanical structural connection of the left wheel and the right wheel, and the problem can not occur when the left wheel and the right wheel are independently steered. Therefore, the automatic adjusting device for the vehicle toe-in has certain reference significance to the design of a future vehicle steering system.

Drawings

Fig. 1 is a schematic view of a forward toe phenomenon of a conventional vehicle caused by inward inclination of front ends of left and right wheels.

Fig. 2 is a schematic view of a negative toe-in phenomenon of the conventional vehicle due to the occurrence of a situation in which the front ends of the left and right wheels are tilted outward.

Fig. 3 is a schematic view of an application of the automatic vehicle toe-in adjusting apparatus of the present invention.

Fig. 4 is a schematic perspective view of the adjusting mechanism of the automatic toe-in adjusting device of the vehicle shown in fig. 3 after removing a half of the housing of the second housing.

Fig. 5 is a schematic perspective view of the adjusting mechanism of the automatic toe-in adjusting device of the vehicle shown in fig. 4 from another perspective after the whole housing is removed.

Fig. 6 is an exploded perspective view of the adjustment mechanism of fig. 5.

Fig. 7 is a graph showing the results of stress analysis of the two drive wheels of fig. 5.

Fig. 8 is a graph showing the results of strain analysis of the two drive wheels of fig. 5.

Fig. 9 is a graph showing the results of stress analysis after the two driving wheels and the rack of the steering gear in fig. 5 are fixed.

Fig. 10 is a graph showing the results of strain analysis of the two driving wheels of fig. 5 after being fixed to the rack of the steering gear.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It will be understood that when an element is referred to as being "mounted on" another element, it can be directly on the other element or intervening elements may also be present. When a component is referred to as being "disposed on" another component, it can be directly on the other component or intervening components may also be present. When an element is referred to as being "secured to" another element, it can be directly secured to the other element or intervening elements may also be present.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "or/and" includes any and all combinations of one or more of the associated listed items.

Referring to fig. 3, the automatic adjusting device for toe-in of a vehicle of the present embodiment is mainly applied to vehicles, especially formula cars. The vehicle mainly includes two wheels (not shown), which are referred to herein as the left and right wheels in front of the vehicle, a rack bar 1 in a steering gear that assists in steering the two wheels, and two tie rods (not shown) that are mounted on opposite ends of the rack bar 1 in the steering gear. The automatic vehicle toe-in adjusting device is used for adjusting the relative length of the two tie rods relative to the two wheels so as to realize toe-in adjustment of the vehicle.

Referring to fig. 4 and 5, the automatic adjusting device for toe-in of a vehicle includes two adjusting mechanisms respectively mounted on opposite ends of a rack 1 in a steering gear of the vehicle, and the two adjusting mechanisms are respectively used for adjusting relative lengths of a left tie rod and a right tie rod of the vehicle with respect to a left wheel and a right wheel of the vehicle during driving of the vehicle, so as to adjust toe-in of the vehicle. Each adjusting mechanism comprises a tie rod joint 4, a toe-in adjusting joint, a driving wheel 6, a motor 5, a displacement sensor (not shown), a controller (not shown), a first shell 3 and a second shell 13. The toe-in adjustment joint includes: the device comprises a joint rod 8, a driven wheel 9, a gear shaft 2, a deep groove ball bearing 10 and a thrust ball bearing 11.

The tie rod joint 4 is fixed on the corresponding tie rod, the tie rod joint 4 can be in a groove-shaped structure, so that one end of the tie rod can extend into the groove-shaped structure and then be fixed through a fastener, and the fastener can be a screw, a bolt and the like, as long as the tie rod and the tie rod joint 4 can be mutually fixed.

Referring to fig. 6, one end of the joint rod 8 is fixed to the tie rod joint 4, and the opposite end of the joint rod 8 is in transmission connection with the driven wheel 9 through a thrust ball bearing 11. The design of the thrust ball bearing 11 enables the driven wheel 9 not to drive the joint rod 8 to rotate when rotating, and only pulls or pushes the joint rod 8 to move correspondingly when the driven wheel 9 moves axially.

One end of the gear shaft 2 is in transmission connection with the driven wheel 9 through a deep groove ball bearing 10, and the design of the deep groove ball bearing 10 enables the driven wheel 9 to rotate and drive the gear shaft 2 to rotate. The opposite end of the pinion shaft 2 is inserted into an end surface of a corresponding end of the rack 1 in the steering gear by means of a screw connection. Because the gear shaft 2 is screwed in the rack 1 in the steering gear, the driven wheel 9 can be rotated to enable the gear shaft 2 to be screwed in or screwed out of the rack 1 in the steering gear, so that the elongation of the gear shaft 2 exposed out of the rack 1 in the steering gear is changed. A threaded hole for screw-fitting with the gear shaft 2 may be opened in advance in the end face of the rack 1 in the steering gear. In order to ensure that the automatic vehicle toe-in adjusting device runs stably and achieves high-performance adjusting performance, the centers of the tie rod joint 4, the joint rod 8, the driven wheel 9, the gear shaft 2 and the rack 1 in the steering gear are all located on the same straight line. The deep groove ball bearing 10 can also reduce the rotational friction of the gear shaft 2 and prevent the first cover 33 and the second cover 34 described below from rotating synchronously with the gear shaft 2.

The invention changes the elongation of the gear shaft 2 exposed outside the rack 1 of the steering gear under the assistance of the deep groove ball bearing 10 by the rotation of the driven wheel 9, and pushes or pulls the tie rod joint 4 under the assistance of the thrust ball bearing 11, thereby realizing the synchronous adjustment of the corresponding tie rod and the corresponding elongation. The invention can realize the real-time synchronization of the adjustment of the relative lengths of the left and right tie rods of the vehicle relative to the left and right wheels of the vehicle and the adjustment of the elongation of the gear shaft 2 exposed outside the rack 1 in the steering gear on the premise of simple structure, easy maintenance and easy maintenance, which is one of the important design points of the invention,

the driving wheel 6 is meshed with the driven wheel 9, and the motor 5 drives the driving wheel 6 to rotate. When motor 5 starts like this, can rotate action wheel 6, drive through action wheel 6 and follow the rotation of driving wheel 9, follow the rotation of driving wheel 9 and when the pulling or promote the tie rod, reduce in real time or increase the elongation that gear shaft 2 exposes rack 1 in the steering gear outside.

And the displacement sensor detects the elongation in real time, and the elongation represents the relative length of the corresponding tie rod. The displacement sensor can adopt a laser displacement sensor, the laser displacement sensor can monitor the elongation of the gear shaft, and the controller is convenient to adjust the toe-in to carry out accurate control.

The controller judges whether the elongation is within a preset elongation range or not, and if not, the driving motor 5 is driven to rotate the driving wheel 6, so that the driving wheel 6 drives the driven wheel 9 to rotate, the elongation is adjusted, the elongation is within the preset elongation range, and the toe-in adjustment of the vehicle is realized. The invention realizes the self-adaptive automatic control of toe-in regulation by designing data acquisition (realized by a displacement sensor), data processing and decision issuing (realized by a controller) and decision execution (realized by a motor 5), thereby realizing intellectualization and embodying science and technology.

The first housing 3 can improve the safety performance of the driven wheel 9. The driven wheel 9 is accommodated in the first shell 3, and part of the gear of the driven wheel 9 is exposed out of the first shell 3 to be meshed with the driving wheel 6. The joint rod 8 and the gear shaft 2 are connected with the driven wheel 9 by extending into the first shell 3. In other embodiments, the first housing 3 may not be provided.

In this embodiment, a window 31 is formed on one side of the first housing 3, and two through holes 32 are formed on the first housing 3 and located on two opposite sides of the window 31 respectively. One end of the joint rod 8 is in transmission connection with the driven wheel 9 through one of the through holes 32, and the opposite end of the joint rod 8 is fixed on the tie rod joint 4. One end of the gear shaft 2 is in transmission connection with the driven wheel 9 through another through hole 32, and part of the gears of the driven wheel 9 are exposed out of the first shell 3 through the window 31 to be meshed with the driving wheel 6. In the design of the first housing 3, the first housing 3 may include a first cover 33 and a second cover 34 that are covered with each other, two through holes 32 are respectively formed on the first cover 33 and the second cover 34, and the window 31 is formed at the joint of the first cover 33 and the second cover 34. The first cover body 33 and the second cover body 34 can be in a shape like a Chinese character 'ji', the protruding parts of the first cover body 33 and the second cover body 34 are opposite to form a containing space for containing the driven wheel 9, and two ends of the first cover body 33 are respectively fixed with two ends of the second cover body 34. The first cover 33 and the second cover 34 can be fixed by a plurality of screws 12.

The second casing 13 can improve the safety performance of the driving wheel 6 and the driven wheel 9, and the second casing 13 accommodates the first casing 3 and the driving wheel 6. The second shell 13 wraps the driving wheel 6 and the toe-in adjusting joint, the toe-in adjusting joint has a moving space in the second shell 13, the second shell 13 is fixed at the chassis part of the racing car to limit the toe-in adjusting range, and the tie rod joint is provided with a displacement sensor to facilitate accurate adjustment of the toe-in.

When the automatic vehicle toe-in adjusting device of the embodiment is used, the automatic vehicle toe-in adjusting method comprises the following steps:

step one, mounting a vehicle toe-in automatic adjusting device on a vehicle;

secondly, acquiring the elongation of a gear shaft 2 of the automatic vehicle toe-in adjusting device, which is exposed outside a rack 1 in a steering gear;

step three, judging whether the elongation is within a preset elongation range;

and step four, if the elongation is not in the preset elongation range, driving the motor 5 to adjust the elongation so that the elongation is in the preset elongation range, and realizing toe-in adjustment of the vehicle.

From the introduction, the automatic vehicle toe-in adjusting device adopts the threaded transmission mechanism to realize the extension and contraction of the toe-in adjusting joint, so that the tie rod joint is synchronously extended and contracted, the tie rod is pulled, the wheel is driven to rotate around the main pin, and the toe-in adjustment is realized. While the screw drive can transmit a large axial force with a small rotational torque. Therefore, the torque required by the selected motor in the automatic vehicle toe-in adjusting device does not need to be too large, and the size of the motor is not too large, so that the automatic vehicle toe-in adjusting device has the advantages of small size, simple structure, low application cost and the like.

For this reason, detailed data analysis is given in the present embodiment. The vehicle toe-in automatic adjusting device needs to overcome the steering resistance moment of a vehicle such as a racing vehicle when in work. And when the racing car is in an in-situ static steering state, the resistance moment is maximum. Therefore, the racing car can start the device in a stationary manner, and the device is subjected to the largest working load.

(1) Steering system calculated load

According to the calculation formula of the pivot steering resistance moment of the racing car:

G＝mgi (1)

wherein: g is the vertical load of the steering wheel of the racing car; m is the total weight of the racing car; g is the acceleration of gravity, 9.8m/s²(ii) a i is the front wheel load ratio of the racing car; m is the pivot steering resistance moment of the racing car; f is the sliding friction coefficient between the tire and the ground, and the value is generally 0.7; and p is the tire inflation pressure.

(2) Steering gear output force of racing car

According to the steering working principle of the racing car, when the racing car steers, the torque of the output force of the steering gear to the kingpin is larger than the pivot steering resistance torque of the tire, and the formula is^[6]：

Wherein: f is the output force of the steering gear; l is the length of the trapezoidal arm; theta is a kingpin inclination angle; eta is the positive efficiency of the steering ladder mechanism.

The parameters of the whole formula car are shown in the following table 1:

TABLE 1

Pivot steering torque:

G=300×0.98×0.47＝1381.8N

output force of the steering gear:

(3) output torque calculation of the electric machine 5

The device wants to change the toe-in of the wheel. After the output torque of the motor 5 is transmitted by the gear (i.e. the driving wheel 6) at the output shaft and the screw thread at the gear shaft part (i.e. the driven wheel 9), the force generated to the tie rod joint is at least larger than the steering gear output force calculated in the above.

The most important to overcome in a screw drive is the friction torque of the screw. According to the literature^[7]The calculation formula of the middle thread transmission, the thread friction torque:

ρ＝arctanf (5)

wherein: λ is the helix lead angle; n is the number of thread lines; p is a screw pitch; (ii) a d₂The pitch diameter of the thread; f is the friction factor, typically 0.09; ρ is the equivalent friction angle. The parameters of the drive thread section designed in the device are as follows in table 2:

TABLE 2

Calculating to obtain:

ρ＝arctan0.09＝0.0898°

considering that in actual operation there may be other resistance in the screw drive, the target torque is set to 0.5 n.m. Gear tooth number Z at output shaft of motor in device₁23, number of gear teeth Z at gear shaft₂Is 17.

The torque required by the small motor is:

according to the calculation result, the device only needs to select a small motor with the rated torque of 0.75 Nm. Generally speaking, without a reducer. The rated torque of the motor is proportional to the size of the motor. Therefore, the size of the motor should be small, the total volume of the device is not too large, and the device does not occupy the space of the front cabin of the racing car excessively and affect the placement and driving of the legs of the driver.

In order to ensure the safety of important parts in the device, the assembled gear transmission part and screw transmission part components in the device are converted into a 'stp' format according to the working load born by the device under the limit working condition obtained in the calculation, and then are introduced into an ANSYS workbench for static analysis [8 ].

First is gear transmission statics analysis. The material of the selected gears and gear shafts is typically 45 steel. The density of the powder is 7890kg/m³Elastic deformation of 2.09X 10¹¹Pa, Poisson's ratio of 0.269, yield strength 355 MPa. The material is added to ANSYS workbench according to the parameter information, and is selected when the parts are introduced.

When the gear transmission part is just started to work, the gear shaft is regarded as a static fixed state, and the gear transmits torque to the gear shaft. Therefore, the gear shaft is fixed, and torque is applied to the gear. The torque value is 676N · m as a result of the above calculation. The mesh is divided into triangles, the size is set as default, and the model is divided into 160686 nodes and 61681 units. The analysis results are shown in FIGS. 7 and 8.

According to the results shown in the figure, the maximum value of equivalent stress in gear transmission under the limit working state is 66.105Mpa, and the maximum value of displacement is 3.309 multiplied by 10^-4mm. According to the mechanical property parameters of the materials mentioned above, the maximum stress borne by the gear transmission is below the safe allowable stress.

The second is an analysis of the threaded drive connection. The material of the rack is still 45 steel. When the screw transmission part is just started to work, the rack is regarded as a static fixed state. The pinion shaft is affected by both the steering resistance and the torque transmitted by the pinion. Before the stress condition is set, the connection relationship between the gear shaft and the rack is set as a threaded connection, and the parameters of the threads are the same as those of the previous step.

The rack was then fixed and, according to the above calculations, a force of 670N and a resisting torque of 500N · m was applied to the gear shaft. The mesh division selects a triangle, the size of the mesh is set to be 2mm, and the model is divided into 128244 nodes and 76664 units. The analysis results are shown in FIGS. 9 and 10. According to the result of the illustration canIt is known that the maximum value of equivalent stress in the screw thread transmission under the extreme working state is 55.494MPa, and the maximum value of displacement is 2.995 multiplied by 10^-4mm. According to the mechanical property parameters of the materials mentioned above, the maximum stress borne by the screw thread during the transmission is below the safe allowable stress.

The stress condition of the device under the limit working condition is calculated. And the stress analysis module of the ANSYS workbench analyzes the stress of the device according to the calculation result, and provides basis and guarantee for the safety of the device.

In the tableIs the toe angle, V is the vehicle speed, and δ is the front wheel steering angle.

By table 3 idealThe V/delta relation table can obtain corresponding toe-in angles under the conditions of different vehicle speeds V and front wheel turning angles deltaCombined with actual toe angleObtaining the deviation value of the toe-in anglePID is adopted for feedback control, and the expression form of a PID controller is as follows:set up K_iIs 1.2, K_pIs 5, K_dIs 0.6. The current vehicle speed V and the front wheel steering angle delta are input and calculated by a PID controller, and then a toe-in angle adjusting signal is output.

When the toe-in adjusting signal is received, the motors in the toe-in adjusting devices at the two ends of the rack rotate at the same speed in the opposite directions, so that the gear at the output shaft is driven to rotate, the gear is meshed with the gear shaft, and the gear shaft can also rotate. The pinion shaft portion is threaded and screwed into the interior of the end of the rack, so that the pinion shaft will move telescopically relative to the rack. Meanwhile, the thrust ball bearing, the left joint shell and the right joint shell are pushed or pulled to move, and the deep groove ball bearing can reduce the rotation resistance of the gear shaft. The movement of the toe-in adjusting joint drives the movement of the tie rod joint, so that the tie rod is driven to pull the wheel to rotate around the main pin, and toe-in is adjusted. And a displacement sensor at the tie rod joint can monitor the displacement of the tie rod joint, and then the toe-in adjusting value of the wheel is calculated through the geometric relationship of the steering mechanism, so that the toe-in is accurately adjusted.

The automatic adjusting device for the toe-in of the vehicle can pull the cross pull rod to further pull the wheel to rotate around the main pin. This is also one of the principles of the steering system to effect racing turns. Therefore, if the toe adjustment joint of the device has enough telescopic stroke, the device can also independently realize the steering function of the racing car and realize the unmanned steering of the racing car, and in addition, the existence of the automatic toe adjustment device of the vehicle cannot influence the driving of a driver, thereby providing a new idea for the design of the steering system of the university student unmanned formula racing car.

When the steering wheel is used as an unmanned steering system, independent steering of the left wheel and the right wheel of the front axle of the racing car can be realized. For the steering system of the unmanned vehicle, the optimal steering effect is as follows: when the racing car passes through a curve, the decision-making mechanism calculates the most appropriate inner and outer wheel turning angles according to information such as road conditions and speed, considering characteristics such as tire cornering and principles such as ackermann steering geometry of the racing car, and then the control system of the racing car controls an unmanned steering system of the racing car to execute the steering. In the conventional integral steering, the steering angle of the left wheel and the right wheel can hardly reach the target angle simultaneously due to the mechanical structural connection of the left wheel and the right wheel, and the problem can not occur when the left wheel and the right wheel are independently steered. Therefore, the automatic adjusting device for the vehicle toe-in has certain reference significance to the design of a future vehicle steering system.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above examples are merely illustrative of several embodiments of the present invention, and the description thereof is more specific and detailed, but not to be construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present invention should be subject to the appended claims.