Lower cross arm connecting structure and steering structure for steer-by-wire vehicle and control method of lower cross arm connecting structure and steering structure
阅读说明：本技术 一种用于线控转向车辆上的下横臂连接结构和转向结构及其控制方法 (Lower cross arm connecting structure and steering structure for steer-by-wire vehicle and control method of lower cross arm connecting structure and steering structure ) 是由 靳立强 任思佳 张志阳 牟希东 靳博豪 张骁 郭垠锴 于 2019-11-08 设计创作，主要内容包括：本发明公开了一种用于线控转向车辆上的下横臂连接结构,包括：转向节；转向电机座,其固定设置在所述转向节的一侧,所述转向电机座一侧开设有第一轴孔；下横臂,其一侧设置有两个支耳,所述支耳内部设置有第二轴孔；销轴,其同时穿过所述第二轴孔和所述第一轴孔,使所述下横臂与所述转向电机座转动连接；两个轴套,其分别套设在所述销轴的两端,两个第一轴承,其内圈分别对应套设在所述轴套的另一端上；两个压盖,其分别对应抵靠在在所述第一轴承的外圈上,并与所述第二轴孔固定连接,所述压盖上沿轴向方向开设有内螺纹孔；两个压紧螺栓。本结构能够在车轮跳动时,防止电机座与下横臂在车辆运动时产生间隙。(The invention discloses a lower cross arm connecting structure used on a steer-by-wire vehicle, which comprises: a knuckle; the steering motor base is fixedly arranged on one side of the steering knuckle, and a first shaft hole is formed in one side of the steering motor base; the lower cross arm is provided with two support lugs on one side, and a second shaft hole is formed in each support lug; the pin shaft penetrates through the second shaft hole and the first shaft hole simultaneously to enable the lower cross arm to be connected with the steering motor base in a rotating mode; the two shaft sleeves are respectively sleeved at two ends of the pin shaft, and the inner rings of the two first bearings are respectively sleeved at the other ends of the shaft sleeves correspondingly; the two pressing covers are correspondingly abutted against the outer ring of the first bearing respectively and are fixedly connected with the second shaft hole, and an internal threaded hole is formed in each pressing cover along the axial direction; two hold-down bolts. This structure can prevent that motor cabinet and lower xarm from producing the clearance when the vehicle motion when the wheel is beated.)
1. A lower cross arm connection structure for a steer-by-wire vehicle, comprising:
a knuckle;
the steering motor base is fixedly arranged on one side of the steering knuckle, and a first shaft hole is formed in one side of the steering motor base;
the lower cross arm is provided with two support lugs on one side, and a second shaft hole is formed in each support lug;
the pin shaft penetrates through the second shaft hole and the first shaft hole simultaneously to enable the lower cross arm to be connected with the steering motor base in a rotating mode;
the two shaft sleeves are respectively sleeved at two ends of the pin shaft, and one end of each shaft sleeve is abutted against one end of the first shaft hole;
the inner rings of the two first bearings are respectively sleeved on the other end of the shaft sleeve correspondingly;
the two pressing covers are correspondingly abutted against the outer ring of the first bearing respectively and are fixedly connected with the second shaft hole, and an internal threaded hole is formed in each pressing cover along the axial direction;
and one end of each of the two compression bolts is provided with an external thread and is respectively arranged at the internal thread hole in a matching way, and the other end of each of the two compression bolts is abutted against the end surface of the pin shaft.
2. The lower cross arm connection structure for a steer-by-wire vehicle according to claim 1, wherein both ends of the knuckle extend outward to form a first extension and a second extension, respectively, and the steering motor base is fixedly provided on the first extension.
3. The lower cross arm connecting structure for the steer-by-wire vehicle as recited in claim 2, wherein said steering motor base is further provided with a groove; and
further comprising: the second bearing is arranged at the bottom of the steering motor base, a bearing outer ring of the second bearing is in interference fit with the groove, and a bearing inner ring of the second bearing abuts against the first extending part.
4. The lower cross arm connection structure for a steer-by-wire vehicle according to claim 3, wherein the first bearing and the second bearing are both tapered roller bearings.
5. The lower cross arm connection structure for a steer-by-wire vehicle according to claim 4, wherein a power output of the steering motor is fixedly connected to the first extension portion after passing through the second bearing.
6. The lower cross arm connection structure for a steer-by-wire vehicle according to claim 5, wherein a lower hole is opened in the first extension portion, and a key is provided in the lower hole.
7. The lower cross arm connecting structure for a steer-by-wire vehicle according to claim 6, wherein a key groove is provided on a power output end of the steering motor and is provided to match with the key, fixing the power output end of the steering motor to the knuckle.
8. The lower cross arm connection structure for a steer-by-wire vehicle according to claim 7, wherein a shoulder is provided on the other end of the boss, and the inner race of the first bearing is provided on the shoulder.
9. A steering structure for use in a steer-by-wire vehicle, characterized by using the lower cross arm connection structure for use in a steer-by-wire vehicle according to any one of claims 1 to 8, further comprising:
the steering motor is fixedly arranged on the steering motor base;
and the power output end of the steering motor penetrates through the steering motor base and is fixedly connected with the steering knuckle.
10. A control method for a steering structure on a steer-by-wire vehicle, characterized by comprising:
when the vehicle is turning, the steering wheel angle α and the vehicle speed v are input into the fuzzy controller to output the theoretical wheel angle
Theoretical turning angle of wheel in ith control process
Wherein the steering wheel angle α, the vehicle speed v, and the theoretical angle of rotation of the wheel
the theoretical turning angle
the empirical formula of the working current of the steering motor in the control process is as follows:
in the formula IeFor a set working current, i is a steering transmission ratio, β is a steering wheel angle, theta is an automobile mass center deflection angle, L is a reduction box output shaft length, and r is a reductionThe radius of an output shaft of the speed box, m is the mass of the automobile, v is the speed of the automobile, t is the running time of the automobile, and C is a compensation constant.
Technical Field
The invention relates to a lower cross arm connecting structure and a steering structure for a steer-by-wire vehicle and a control method thereof, belonging to the field of automobile steering control.
Background
The Wire-controlled steering, namely 'ser-By-Wire', belongs to one of the Wire-controlled technologies 'X-By-Wire'. steer-By-Wire was originally derived from aerospace technology and from "Fly-By-Wire" for aviation driving, and subsequently, with the development of electronic technology and control technology, more and more people began to study the application of steer-By-Wire in the automotive field.
As early as the 60's of the 20 th century, Kasselmann, germany, attempted to replace mechanical steering systems with electronic control systems, but limited by the state of the art that has not been successful. In 1990, the german gallop company started the research of steer-by-wire and introduced an F400Carving concept car based on the research of steer-by-wire. In 2000, BMW introduced a Z22 concept vehicle, and the steering angle of the steering wheel was reduced by an appropriate control strategy, thereby reducing the operation difficulty of the driver. In 2010, Toyota corporation introduced a FT-EV II concept vehicle, and the functions of accelerating and braking the vehicle were realized through knobs and keys. In 2015, inflixianidi introduced the first global mass-produced vehicle model Q50 to which steer-by-wire was applied.
The domestic research on steer-by-wire began late, beginning in the 90 s of the 20 th century. With the promotion of national policies, many powerful enterprises such as gasoline, east wind and the like and all scientific research units increase the research on steering vehicles and produce a series of achievements.
Along with the improvement of the requirements of people on living standard and the continuous deterioration of the environment in recent years, the energy-saving, environment-friendly and safety subjects of automobiles are increasingly emphasized by people and receive more and more attention, and the in-wheel motor steer-by-wire vehicle shows wide prospects.
Disclosure of Invention
The invention designs and develops a lower cross arm connecting structure for a steer-by-wire vehicle, which can enable a motor base to rotate around a pin shaft through the matching of a first bearing and a pressing mechanism when wheels jump, prevent the motor base and the lower cross arm from generating a gap when the vehicle moves and improve the stability when the vehicle moves.
The invention also designs and develops a steering structure for the steer-by-wire vehicle, which can directly drive the steering knuckle and the wheels to rotate through the steering motor when the vehicle steers, and has flexible rotation and large steering angle.
The invention also designs and develops a control method for the steering structure of the steer-by-wire vehicle, which improves the control precision of the steering angle and the steering angle of the wheels in the steering process by monitoring the driving parameters in the steering process and controlling the actual turning angle of the wheels by a control system.
The technical scheme provided by the invention is as follows:
a cross arm connection for use above and below a steer-by-wire vehicle, comprising:
a knuckle;
the steering motor base is fixedly arranged on one side of the steering knuckle, and a first shaft hole is formed in one side of the steering motor base;
the lower cross arm is provided with two support lugs on one side, and a second shaft hole is formed in each support lug;
the pin shaft penetrates through the second shaft hole and the first shaft hole simultaneously to enable the lower cross arm to be connected with the steering motor base in a rotating mode;
the two shaft sleeves are respectively sleeved at two ends of the pin shaft, and one end of each shaft sleeve is abutted against one end of the first shaft hole;
the inner rings of the two first bearings are respectively sleeved on the other end of the shaft sleeve correspondingly;
the two pressing covers are correspondingly abutted against the outer ring of the first bearing respectively and are fixedly connected with the second shaft hole, and an internal threaded hole is formed in each pressing cover along the axial direction;
and one end of each of the two compression bolts is provided with an external thread and is respectively arranged at the internal thread hole in a matching way, and the other end of each of the two compression bolts is abutted against the end surface of the pin shaft.
Preferably, both ends of the knuckle respectively extend outwards to form a first extension part and a second extension part, and the steering motor base is fixedly arranged on the first extension part.
Preferably, the steering motor base is further provided with a groove; and
further comprising: the second bearing is arranged at the bottom of the steering motor base, a bearing outer ring of the second bearing is in interference fit with the groove, and a bearing inner ring of the second bearing abuts against the first extending part.
Preferably, the first bearing and the second bearing are both tapered roller bearings.
Preferably, the power output end of the steering motor passes through the second bearing and then is fixedly connected with the first extension part.
Preferably, the first extending portion has a lower hole, and the lower hole has a key.
Preferably, a key groove is formed in the power output end of the steering motor, and is matched with the key, so that the power output end of the steering motor is fixed with the steering knuckle.
Preferably, a shoulder is provided on the other end of the sleeve, and the inner race of the first bearing is provided on the shoulder.
A steering structure for use in a steer-by-wire vehicle, using a lower cross arm connection structure for use in a steer-by-wire vehicle, comprising:
the steering motor is fixedly arranged on the steering motor base;
and the power output end of the steering motor penetrates through the steering motor base and is fixedly connected with the steering knuckle.
A control method for a steering structure on a steer-by-wire vehicle, characterized by comprising:
when the vehicle is turning, the steering wheel angle α and the vehicle speed v are input into the fuzzy controller to output the theoretical wheel angle
Theoretical turning angle of wheel in ith control process
Wherein the steering wheel angle α, the vehicle speed v, and the theoretical angle of rotation of the wheel
the theoretical turning angle
the empirical formula of the working current of the steering motor in the control process is as follows:
in the formula IeFor a set operating current, i is the steering driveThe ratio is β, theta is the steering wheel angle, theta is the automobile mass center deflection angle, L is the reduction gearbox output shaft length, r is the reduction gearbox output shaft radius, m is the automobile mass, v is the automobile speed, t is the automobile running time, and C is the compensation constant.
The invention has the following beneficial effects: the invention provides a connecting structure for a lower cross arm of a wheel hub motor steer-by-wire vehicle, which can adjust the clearance between a steering motor base at a hinged position and the lower cross arm, ensure that the axial clearance at the connecting position of the steering motor base and the lower cross arm is not changed, prevent the relative motion between the steering motor base and the lower cross arm when the vehicle moves and improve the safety, the stability and the smoothness when the vehicle moves.
The structure can fix the axial relative position between the steering motor base and the lower cross arm, prevent the problems of wheel shake and inaccurate steering angle caused by axial movement between the steering knuckle and the lower cross arm due to the clearance caused by manufacturing error, abrasion deformation and the like at the joint of the lower cross arm, and improve the performance of the vehicle during movement.
Drawings
Fig. 1 is a schematic structural view of a steering system of a steer-by-wire vehicle according to the present invention.
Fig. 2 is a schematic structural view of the connection between the steering motor base and the lower cross arm.
Fig. 3 is an exploded view of the connection structure of the steering motor base and the lower cross arm according to the present invention.
Fig. 4 is a schematic cross-sectional view of the connection between the steering motor base and the lower cross arm according to the present invention.
Fig. 5 is a partially enlarged schematic view of the joint of the steering motor base and the lower cross arm.
Detailed Description
The present invention is further described in detail below with reference to the attached drawings so that those skilled in the art can implement the invention by referring to the description text.
As shown in fig. 1 to 5, the present invention provides a lower cross arm connecting structure for a steer-by-wire vehicle, comprising: the steering knuckle comprises a steering knuckle 100, a steering motor base 200, a lower cross arm 400, a spring shock absorber 500, a hub motor 600 and an upper cross arm 700.
As shown in fig. 1, both ends of the knuckle 100 extend toward one side of the knuckle 100 to form a first extension 110 and a second extension 120, the other side of the knuckle 100 is provided with a hub motor 600 and a brake caliper 610, a steering motor base 200 is fixedly arranged on the first extension 110, an upper cross arm 700 is fixedly connected to the second extension 120, a lower cross arm 400 is rotatably connected to one side of the motor base 200, and a spring damper 500 is connected between the upper cross arm 700 and the lower cross arm 400.
As shown in fig. 2 to 5, a first shaft hole 220 is formed at one side of the motor base 200, two support lugs 410 are provided at one side of the lower cross arm 400 facing the motor base 200, and a second shaft hole 411 is formed at the support lugs 410 along the axial direction.
In the present invention, it is preferable that the second shaft hole 411 has a stepped structure. Including first step portion, second step portion and third step portion, wherein, first step portion has the internal thread, and first step portion, second step portion and the coaxial setting of third step portion and diameter reduce in proper order.
The two ends of the pin shaft 210 are respectively sleeved with a shaft sleeve 250, one end of the pin shaft 210 penetrates through the second shaft hole 411 and the first shaft hole 220 to rotatably connect the motor base 200 and the lower cross arm 400, one end of the shaft sleeve 210 abuts against the end surface of the first shaft hole 220, the other end of the shaft sleeve 210 is provided with a shoulder, the first bearing 260 is arranged on the shoulder, the inner bearing ring of the first bearing 260 abuts against the shoulder and is in interference fit with the shoulder, the shaft sleeve 210 is located in the second step portion and is provided with a sealing ring 240, and the first bearing 260 is located above the sealing ring 240. The pin 210 is in transition fit with the first shaft hole 220 and the shaft sleeve 250.
The gland 270 has an external thread, and can be matched with the internal thread of the first stepped portion to fix the gland 270 to the first stepped portion. The gland 270 sets up at the top of bearing 260 to compress tightly first bearing 260 through the cooperation of gland 270 and first step portion, put at the central point of gland 270, seted up the internal thread hole along the axial, the one end of clamp bolt 280 has the external screw thread with internal thread hole assorted, the other end of clamp bolt 280 passes internal thread hole and first bearing 260 back in proper order, supports and leans on the terminal surface of round pin axle 210.
In the present invention, it is preferable that the first bearing 260 is a tapered roller bearing.
During installation, the first bearing 260 is pressed by screwing the gland 270, and then the shaft sleeve 250 is pressed by the first bearing 260, so that one end of the shaft sleeve 250 abuts against the end face of the first shaft hole 220 of the motor base 200, and the relative position between the motor base 200 and the lower cross arm 400 is fixed. By tightening the hold-down bolt 280, the position of the pin shaft 210 in the axial direction can be fixed, and the pin shaft 210 is prevented from shaking left and right to generate noise when the vehicle runs.
During installation, grease lubrication is needed between the first bearing 260 and the pin shaft 210, the lubrication degree is increased, and noise generated during vehicle movement is reduced. In the process of wheel flipping, the motor base 200 and the lower cross arm 400 rotate around the pin shaft 210, at this time, the shaft sleeve 250, the inner ring of the first bearing 260 and the pin shaft 210 rotate along with the rotation of the motor base 200, and the outer ring of the first bearing 260, the gland 270 and the compression bolt 280 are kept consistent.
Compared with the traditional method that a smooth through hole is formed in the steering motor base and the lower cross arm, and the pin shaft directly penetrates through the steering motor base and the lower cross arm, the structure is in threaded fit with the second shaft hole 411 through the gland 270 to tightly press the shaft sleeve 250, so that the problems of wheel shaking and inaccurate steering angle caused by axial displacement between the motor base 200 and the lower cross arm 400 during vehicle movement due to a gap between the motor base 200 and the lower cross arm 400 caused by manufacturing, friction and the like can be effectively prevented, and the safety, the stability and the smoothness during vehicle movement are improved.
The present invention also provides a steering structure for a steer-by-wire vehicle, comprising: the steering knuckle comprises a steering knuckle 100, a steering motor base 200, a steering motor 300, a lower cross arm 400, a spring shock absorber 500, a hub motor 600 and an upper cross arm 700.
As shown in fig. 1, both ends of a knuckle 100 extend to one side of the knuckle 100 to form a first extension 110 and a second extension 120, the other side of the knuckle 100 is provided with a hub motor 600 and a brake caliper 610, a steering motor base 200 is fixedly arranged on the first extension 110, a steering motor 300 is fixedly arranged on the motor base 200, an upper cross arm 700 is fixedly connected to the second extension 120, a lower cross arm 400 is rotatably connected to one side of the motor base 200, and a spring damper 500 is connected between the upper cross arm 700 and the lower cross arm 400.
The upper cross arm 700 is connected with the second extending portion 120 of the steering knuckle 100 through a ball pin, the power output end of the steering motor 300 is connected with the reduction gearbox 310, the steering motor 300 is fixedly connected with the reduction gearbox 310 through a bolt, and the reduction gearbox 310 is fixed with the steering motor base 200 through a bolt.
The center of the steering motor base 200 is provided with a groove 230, the rotating bearing is arranged in the groove 230, the outer ring of the rotating bearing is in interference fit with the groove 230, the inner ring of the rotating bearing abuts against the top of the first extending part 110, and the first extending part 110 is provided with a lower hole, wherein the groove 230, the rotating bearing and the lower hole are coaxially arranged, the lower hole is internally provided with a key, and the output end of the reduction gearbox 310 is provided with a key groove, so that the output end of the reduction gearbox 310 can drive the steering knuckle 100 to rotate by the rotation of the steering motor 300 after sequentially passing through the inner ring and the lower hole of the rotating bearing and is fixedly connected with the first extending part 110.
In the present invention, it is preferable that the rotary bearing is a tapered roller bearing.
As shown in fig. 2 to 5, a first shaft hole 220 is formed at one side of the motor base 200, two support lugs 410 are provided at one side of the lower cross arm 400 facing the motor base 200, and a second shaft hole 411 is formed at the support lugs 410 along the axial direction.
In the present invention, it is preferable that the second shaft hole 411 has a stepped structure. Including first step portion, second step portion and third step portion, wherein, first step portion has the internal thread, and first step portion, second step portion and the coaxial setting of third step portion and diameter reduce in proper order.
The two ends of the pin shaft 210 are respectively sleeved with a shaft sleeve 250, one end of the pin shaft 210 penetrates through the second shaft hole 411 and the first shaft hole 220 to rotatably connect the motor base 200 and the lower cross arm 400, one end of the shaft sleeve 210 abuts against the end surface of the first shaft hole 220, the other end of the shaft sleeve 210 is provided with a shoulder, the first bearing 260 is arranged on the shoulder, the inner bearing ring of the first bearing 260 abuts against the shoulder and is in interference fit with the shoulder, the shaft sleeve 210 is located in the second step portion and is provided with a sealing ring 240, and the first bearing 260 is located above the sealing ring 240. The pin 210 is in transition fit with the first shaft hole 220 and the shaft sleeve 250.
The gland 270 has an external thread, and can be matched with the internal thread of the first stepped portion to fix the gland 270 to the first stepped portion. The gland 270 sets up at the top of bearing 260 to compress tightly first bearing 260 through the cooperation of gland 270 and first step portion, put at the central point of gland 270, seted up the internal thread hole along the axial, the one end of clamp bolt 280 has the external screw thread with internal thread hole assorted, the other end of clamp bolt 280 passes internal thread hole and first bearing 260 back in proper order, supports and leans on the terminal surface of round pin axle 210.
In the present invention, it is preferable that the first bearing 260 is a tapered roller bearing.
During installation, the first bearing 260 is pressed by screwing the gland 270, and then the shaft sleeve 250 is pressed by the first bearing 260, so that one end of the shaft sleeve 250 abuts against the end face of the first shaft hole 220 of the motor base 200, and the relative position between the motor base 200 and the lower cross arm 400 is fixed. By tightening the hold-down bolt 280, the position of the pin shaft 210 in the axial direction can be fixed, and the pin shaft 210 is prevented from shaking left and right to generate noise when the vehicle runs.
During installation, grease lubrication is needed between the first bearing 260 and the pin shaft 210, the lubrication degree is increased, and noise generated during vehicle movement is reduced. In the process of wheel flipping, the motor base 200 and the lower cross arm 400 rotate around the pin shaft 210, at this time, the shaft sleeve 250, the inner ring of the first bearing 260 and the pin shaft 210 rotate along with the rotation of the motor base 200, and the outer ring of the first bearing 260, the gland 270 and the compression bolt 280 are kept consistent.
The invention also provides a control method of the steering structure for the steer-by-wire vehicle, which improves the control precision and efficiency of the wheel turning angle in the steering process by monitoring the driving parameters in the steering process and controlling the actual turning angle of the wheel by the control system.
The steering motor 500 is mainly controlled to rotate by one of three control methods of position, speed and current, different control modes are selected according to different requirements, current loop control is generally selected when a vehicle runs normally, and the vehicle enters position loop control when wheels are ready to steer by 90 degrees.
When the driver rotates the steering wheel, the rotation angle sensor measures the angle of the driver rotating the steering wheel and transmits a corresponding rotation angle signal to the control system. The control system processes the input steering wheel angle signal according to the information such as the vehicle speed signal and the like to obtain the angle which the wheels should rotate, and transmits the corresponding signal to the steering motor controller. The steering motor controller adopts fuzzy PID control, and comprises the following specific steps:
when the vehicle is turning, the steering wheel angle α and the vehicle speed v are input into the fuzzy controller to output the theoretical wheel angle
Theoretical turning angle of wheel in ith control process
Wherein, steering wheel angle α, vehicle speed v, theoretical angle of wheel
Theoretical cornerThe ambiguity field of the deviation e from the actual turning angle theta of the wheel is [ -1,1]The quantification factor is 1; the ambiguity field of the deviation change rate ec is [ -1,1]The quantification factor is 1;
wheel of vehicleThe inter-rotation angle theta is controlled by a PID controller, and in the ith control process, the theoretical rotation angle theta of the wheel is controlled
In the control process, the rotation angle of the steering motor 300 is controlled by controlling the current of the steering motor 300, and the empirical formula of the working current of the steering motor 300 in the control process is as follows:
wherein, IeFor a set operating current, the unit is A, i is a steering transmission ratio, β is a steering wheel angle, the unit is theta, theta is an automobile mass center deflection angle, the unit is DEG, L is a reduction gearbox output shaft length, the unit is mm, r is a reduction gearbox output shaft radius, the unit is mm, m is an automobile mass, the unit is kg, v is an automobile speed, the unit is m/s, t is an automobile running time, the unit is s, and C is a compensation constant.
While embodiments of the invention have been described above, it is not limited to the applications set forth in the description and the embodiments, which are fully applicable in various fields of endeavor to which the invention pertains, and further modifications may readily be made by those skilled in the art, it being understood that the invention is not limited to the details shown and described herein without departing from the general concept defined by the appended claims and their equivalents.
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