Chassis adjustment method and system of medium-sized bus and vehicle

Abstract

The invention discloses a chassis adjusting method and system of a medium-sized bus and a vehicle, and belongs to the technical field of vehicles, the chassis adjusting method comprises the steps that firstly, before a torsion bar spring is assembled, pre-tightening operation is conducted on connecting bolts of a front lining and a rear lining of a lower control arm, and first pre-tightening torque is achieved; then the eccentric gaskets of the front bush and the rear bush are corrected, so that the eccentric gaskets are located at the center positions; after it is confirmed that the first pre-tightening torque is correct and the eccentric gasket is located at the center position, the step of four-wheel positioning adjustment of the vehicle is executed, that is, before four-wheel positioning, the fastening requirement of a connecting bolt in the chassis split charging technology is proposed, internal force generated by deformation of a front bush and a rear bush of the lower control arm is reduced and released, and then the lower control arm is fixed. The working efficiency is improved, standardization of the operation process is achieved, meanwhile, internal force accumulation of a suspension system caused by misoperation is reduced, the problem of deviation of the minibus is solved at the minimum cost, and therefore the driving safety of the minibus is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicles, and in particular to a chassis adjustment method, an adjustment system and a vehicle for a medium-sized bus. Background Art

[0002] The vehicle's ability to drive straight has a significant impact on driving safety and driving experience. If the vehicle is prone to deviation during driving, it will not only easily cause traffic accidents, but also increase the burden on the driver and cause tire wear problems. For medium-sized buses (also known as minibuses), if the off-line vehicles are simply matched through four-wheel alignment, it is easy to cause individual problem handling, making it difficult to ensure production consistency and repeatability. In addition, since minibuses carry a large number of people, it is particularly important to solve the deviation problem in order to improve safety. Summary of the invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a chassis adjustment method for a medium-sized bus, which can effectively solve the problem that the medium-sized bus is prone to deviation and improve the driving safety of the vehicle.

[0004] The present invention also provides a tuning system and a vehicle for executing the above chassis tuning method.

[0005] According to a first aspect of an embodiment of the present invention, a method for adjusting the chassis of a medium-sized bus, the chassis comprises a frame, a left suspension structure, a right suspension structure and a torsion bar spring, the left suspension structure and the right suspension structure respectively comprise an upper control arm, a lower control arm and a steering knuckle, the upper control arm is connected between the frame and the upper part of the steering knuckle; the lower control arm comprises a front connecting arm and a rear connecting arm, the front connecting arm is provided with a front bushing, the rear connecting arm is provided with a rear bushing, one end of the front connecting arm and the rear connecting arm are connected and connected to the lower part of the steering knuckle, the other end of the front connecting arm is connected to the frame through the front bushing, the other end of the rear connecting arm is connected to the frame through the rear bushing, the front bushing and the rear bushing are respectively connected to the frame through connecting bolts, the torsion bar spring is connected to the frame, and the method for adjusting the chassis comprises: Before assembling the torsion bar spring, pre-tightening the connecting bolts of the front bushing and the rear bushing to reach a first pre-tightening torque; Correcting the eccentric washers of the front bushing and the rear bushing so that the eccentric washers are in a centered position; After the first preload torque is correct and the eccentric gasket is centered, the four-wheel alignment adjustment of the vehicle is performed.

[0006] The chassis calibration method for a medium-sized bus according to an embodiment of the present invention has at least the following beneficial effects: The chassis tuning method is aimed at medium-sized buses. First, before assembling the torsion bar spring, the connecting bolts of the front bushing and the rear bushing of the lower control arm are pre-tightened to reach the first pre-tightening torque; then the eccentric washers of the front bushing and the rear bushing are corrected to make the eccentric washers in the center position, that is, the eccentric holes of the eccentric washers are vertically upward; after confirming that the first pre-tightening torque is correct and the eccentric washers are in the center position, the four-wheel alignment adjustment step of the vehicle is performed, that is, before the four-wheel alignment, the tightening requirements of the connecting bolts in the chassis sub-assembly process are proposed to reduce and release the internal force generated by the deformation of the front bushing and the rear bushing of the lower control arm, improve work efficiency and realize standardization of the operation process, while reducing the accumulation of internal forces of the suspension system caused by improper operation, and positively solving the deviation problem that plagues medium-sized buses at the lowest cost, thereby improving the driving safety of the vehicle.

[0007] According to some embodiments of the present invention, the chassis further includes a stabilizer bar, the stabilizer bar includes a bar body and bent sections connected to both ends of the bar body, the frame includes a longitudinal beam and a cross beam connected to each other, and the chassis adjustment method includes: After assembling the torsion bar spring, adjusting the torsion bar spring to achieve a preset torque; After adjusting the torsion bar spring, the rod body is connected to the longitudinal beam, and the bent sections at both ends of the rod body are respectively connected to the lower control arms of the left suspension structure and the right suspension structure.

[0008] According to some embodiments of the present invention, after the stabilizing bar is installed, the method further comprises: Using a level to adjust the steering wheel centering, and after the steering wheel centering, determining whether a difference in toe angles between the left wheel and the right wheel is greater than or equal to a first preset value; When the toe angle difference is greater than or equal to the first preset value, the toe angle difference is made smaller than a second preset value by rotating the steering wheel, and the steering wheel is reassembled, and the second preset value is smaller than the first preset value.

[0009] According to some embodiments of the present invention, performing four-wheel alignment adjustment on a vehicle includes: The height of the chassis, the camber angle of the front wheels, the caster angle and the toe angle of the front wheels are adjusted in sequence.

[0010] According to some embodiments of the present invention, adjusting the height of the chassis includes: The height of the chassis is measured by using an auxiliary tool, and the upper edge of the bracket at the height of both sides of the auxiliary tool is used as a reference. The height of the chassis is adjusted by the adjusting bolt at the rear end of the torsion bar spring, so that the center of the cam bolt of the lower control arm on the front side of the chassis is aligned with the reference surface of the auxiliary tool, and the height tolerance on both sides does not exceed 1mm; After adjusting the height of the chassis, a line is drawn on the corresponding cam bolt head with the reference surface of the auxiliary tool as a reference, and the mark is used for rechecking.

[0011] According to some embodiments of the present invention, adjusting the front wheel toe angle includes: When the initial toe angle of the front wheel is greater than or equal to the third preset value and the value of the kingpin caster angle cannot be read, pre-adjusting the toe angle of the front wheel until the value of the kingpin caster angle can be read; The adjusting of the height of the chassis, the adjusting of the camber angle of the front wheels, the adjusting of the caster angle and the adjusting of the toe angle of the front wheels are performed repeatedly in sequence.

[0012] According to some embodiments of the present invention, a steering tie rod is provided on both sides of the chassis, the steering tie rod on one side is connected to the steering knuckle of the left suspension structure, and the steering tie rod on the other side is connected to the steering knuckle of the right suspension structure, and the two steering tie rods are connected by a connecting rod, and the method for adjusting the toe angle of the front wheel also includes: After the front wheel toe angle is adjusted, the length difference of the steering tie rod assembly on both sides is set to be less than or equal to 3 mm.

[0013] According to some embodiments of the present invention, adjusting the camber angle of the front wheels includes: The connecting torque of the connecting bolts of the front bushing is adjusted to a range of 48 Nm to 52 Nm. After the adjustment is completed, the connecting bolts of the front bushing are tightened according to a second pre-tightening torque, and the range of the second pre-tightening torque is 80 Nm to 120 Nm.

[0014] According to some embodiments of the present invention, adjusting the caster angle includes: On the premise that the front wheel camber angle is qualified, the kingpin caster angle is adjusted, and the connecting torque of the connecting bolt of the rear bushing is adjusted to the range of 48Nm to 52Nm. After the adjustment is completed, the connecting bolt of the rear bushing is tightened according to the third pre-tightening torque, and the range of the third pre-tightening torque is 80Nm to 120Nm.

[0015] According to some embodiments of the present invention, the calibration method further comprises: When the medium-sized bus has a deviation problem, the height of the chassis on one side of the deviation direction is adjusted to be higher than the height on the other side, and the height difference between the two sides is less than or equal to 10 mm; The caster angle of the chassis on one side of the deviation direction is adjusted to be greater than the caster angle on the other side, and the difference between the caster angles on both sides is greater than or equal to 30°.

[0016] A chassis calibration system for a medium-sized bus according to a second aspect of an embodiment of the present invention comprises: The chassis comprises a frame, a left suspension structure, a right suspension structure and a torsion bar spring, the left suspension structure and the right suspension structure respectively comprise an upper control arm, a lower control arm and a steering knuckle, the upper control arm is connected between the frame and the upper part of the steering knuckle; the lower control arm comprises a front connecting arm and a rear connecting arm, the front connecting arm is provided with a front bushing, the rear connecting arm is provided with a rear bushing, one end of the front connecting arm and the rear connecting arm are connected and connected to the lower part of the steering knuckle, the other end of the front connecting arm is connected to the frame through the front bushing, the other end of the rear connecting arm is connected to the frame through the rear bushing, the front bushing and the rear bushing are respectively connected to the frame through connecting bolts, the torsion bar spring is connected to the frame, and the chassis tuning system comprises: A first actuator is configured to pre-tighten the connecting bolts of the front bushing and the rear bushing to reach a first pre-tightening torque before assembling the torsion bar spring; A second actuator is configured to correct the eccentric washers of the front bushing and the rear bushing so that the eccentric washers are in a centered position; The third actuator is configured to perform four-wheel alignment adjustment on the vehicle after the first preload torque is correct and the eccentric spacer is centered.

[0017] The chassis calibration system according to the embodiment of the present invention has at least the following beneficial effects: Before assembling the torsion bar spring, the first actuator is used to pre-tighten the connecting bolts of the front bushing and the rear bushing of the lower control arm and reach the first pre-tightening torque; then the eccentric gaskets of the front bushing and the rear bushing are corrected by the second actuator so that the eccentric gaskets are in a centered position, that is, the eccentric holes of the eccentric gaskets are vertically upward; after confirming that the first pre-tightening torque is correct and the eccentric gaskets are in a centered position, the third actuator is used to perform the steps of adjusting the four-wheel alignment of the vehicle, that is, before the four-wheel alignment, the tightening requirements of the connecting bolts in the chassis assembly process are proposed, the internal force generated by the deformation of the front bushing and the rear bushing of the lower control arm is reduced and released, the work efficiency is improved and the operation process is standardized, while the internal force accumulation of the suspension system caused by improper operation is reduced, and the deviation problem that plagues minibuses is solved positively at the lowest cost, thereby improving the driving safety of the vehicle.

[0018] A vehicle according to a third aspect of an embodiment of the present invention comprises a chassis, and the chassis is calibrated using the chassis calibration method of the first aspect of the embodiment.

[0019] Since the vehicle applies the chassis adjustment method for a medium-sized bus described in the first embodiment, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, which will not be repeated here.

[0020] Other features and advantages of the present invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practicing the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a schematic structural diagram of a chassis of a medium-sized bus according to an embodiment of the present invention; Figure 2 yes Figure 1 A partial schematic diagram of the center left suspension structure and the frame assembly structure; Figure 3 yes Figure 1 A partial schematic diagram of the middle right suspension structure and the frame assembly structure; Figure 4 is a flow chart of a chassis calibration method for a medium-sized bus according to an embodiment of the present invention; Figure 5 is a flow chart of a chassis calibration method for a medium-sized bus according to another embodiment of the present invention; Figure 6 is a flow chart of steps for adjusting the height of a chassis according to an embodiment of the present invention; Figure 7 is a flowchart of steps for adjusting the toe angle of the front wheels according to an embodiment of the present invention; Figure 8 is a flowchart of steps for adjusting the front wheel camber angle and the kingpin caster angle according to an embodiment of the present invention; Fig. 9 The present invention is a flowchart of the steps of correcting the deviation of a medium-sized bus according to an embodiment of the present invention.

[0022] Label: Vehicle frame 100; longitudinal beam 110; cross beam 120; connecting seat 130; Left suspension structure 200; left lower control arm 210; left front connecting arm 211; left front bushing 2111; left rear connecting arm 212; left rear bushing 2121; left steering knuckle 220; Right suspension structure 300; right upper control arm 310; right lower control arm 320; right front connecting arm 321; right front bushing 3211; right rear connecting arm 322; right rear bushing 3221; right steering knuckle 330; Connecting bolt 400; Eccentric spacer 500; Torsion bar spring 600; adjusting bolt 610; Stabilizing rod 700; rod body 710; bending section 720; Steering tie rod 800; connecting rod 810. DETAILED DESCRIPTION

[0023] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0024] In the description of the present invention, it is necessary to understand that the orientation or positional relationship indicated by the terms upper, lower, etc. is based on the orientation or positional relationship shown in the drawings, and is 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 orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0025] In the description of the present invention, the meaning of "more than" is more than two, "greater than", "less than", "exceed" etc. are understood to exclude the number itself, and "above", "below", "within" etc. are understood to include the number itself. If there is a description of "first" or "second", it is only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0026] In the description of the present invention, it should be noted that the terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention in combination with the specific content of the technical solution.

[0027] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the embodiments described below are only some embodiments of the present invention, not all embodiments.

[0028] refer to Figures 1 to 3The chassis of a medium-sized bus according to an embodiment of the present invention is described, and the chassis includes a frame 100, a left suspension structure 200, a right suspension structure 300 and a torsion bar spring 600, wherein the left suspension structure 200 is the left suspension of the front wheel, the right suspension structure 300 is the right suspension of the front wheel, the frame 100 includes two longitudinal beams 110 arranged left and right and a plurality of cross beams 120 connected between the two longitudinal beams 110, the length of the longitudinal beam 110 is greater than the length of the cross beam 120, the left suspension structure 200 is installed on the left side of the frame 100, and the right suspension structure 300 is installed on the right side of the frame 100. Two torsion bar springs 600 are provided, one of which is used to connect the left suspension structure 200 to the frame 100, and the other torsion bar spring 600 is used to connect the right suspension structure 300 to the frame 100. The shock and vibration caused by uneven road surface are absorbed and buffered during the driving of the vehicle. When the wheel encounters an obstacle, the torsion bar spring 600 will be twisted and deformed, converting the up and down movement of the wheel into the torsion deformation of the spring, thereby effectively reducing the impact and vibration of the vehicle and passengers, playing the role of buffering and shock absorption, maintaining the stability of the vehicle body, etc. The left suspension structure 200 and the right suspension structure 300 respectively include an upper control arm, a lower control arm and a steering knuckle, the steering knuckle is used to connect the wheel, the upper control arm is connected between the frame 100 and the upper part of the steering knuckle, and the lower control arm is connected between the frame 100 and the lower part of the steering knuckle.

[0029] The left suspension structure 200 of the front wheel and the right suspension structure 300 of the front wheel are described below with reference to specific examples.

[0030] Reference Figure 2 As shown, Figure 2 A partial schematic diagram of the assembly structure of the left suspension structure 200 and the vehicle frame 100 is shown. The left suspension structure 200 of the front wheel includes a left upper control arm, a left lower control arm 210 and a left steering knuckle 220. One end of the left upper control arm is connected to the upper end of the left steering knuckle 220, and the other end is hinged to the left longitudinal beam 110. The left lower control arm 210 includes a left front connecting arm 211 and a left rear connecting arm 212. The left front connecting arm 211 is provided with a left front bushing 2111, and the left rear connecting arm 212 is provided with a left rear bushing 2121. One end of the left front connecting arm 211 and the left rear connecting arm 212 are connected and connected to the lower end of the left steering knuckle 220. Specifically, the rotation connection can be realized through a spherical mechanism. The left steering knuckle 220 is used to connect the left front wheel. The left front connecting arm 211 is rotatably connected to the cross beam 120 near the front side of the frame 100 through the left front bushing 2111, and the left rear connecting arm 212 is rotatably connected to the longitudinal beam 110 of the frame 100 through the left rear bushing 2121, wherein the cross beam 120 and the longitudinal beam 110 are respectively provided with mounting holes, the left front bushing 2111 is connected to the mounting hole of the cross beam 120 through the connecting bolt 400, and the left rear bushing 2121 is connected to the mounting hole of the longitudinal beam 110 through the connecting bolt 400, thereby realizing the assembly of the left suspension structure 200 of the front wheel and the frame 100.

[0031] Reference Figure 3 As shown, Figure 3 A partial schematic diagram of the assembly structure of the right suspension structure 300 and the vehicle frame 100 is shown. The right suspension structure 300 of the front wheel includes a right upper control arm 310, a right lower control arm 320 and a right steering knuckle 330. One end of the right upper control arm 310 is connected to the upper end of the right steering knuckle 330, and the other end is hinged to the right longitudinal beam 110; the right lower control arm 320 includes a right front connecting arm 321 and a right rear connecting arm 322. The right front connecting arm 321 is provided with a right front bushing 3211, and the right rear connecting arm 322 is provided with a right rear bushing 3221. One end of the right front connecting arm 321 and the right rear connecting arm 322 are connected and connected to the lower end of the right steering knuckle 330. Specifically, the rotation connection can be realized through a spherical mechanism. The right steering knuckle 330 is used to connect the right front wheel. The right front connecting arm 321 is rotatably connected to the cross beam 120 near the front side of the frame 100 through the right front bushing 3211, and the right rear connecting arm 322 is rotatably connected to the longitudinal beam 110 of the frame 100 through the right rear bushing 3221, wherein the cross beam 120 and the longitudinal beam 110 are respectively provided with mounting holes, the right front bushing 3211 is connected to the mounting hole of the cross beam 120 through the connecting bolt 400, and the right rear bushing 3221 is connected to the mounting hole of the longitudinal beam 110 through the connecting bolt 400, thereby realizing the assembly of the right suspension structure 300 of the front wheel and the frame 100.

[0032] The front bushings and rear bushings on the left and right sides are mainly used to fill the gap between the suspension structure and the connecting bolts 400 to achieve the fixing effect. Since the front bushings and rear bushings are made of rubber, they have a certain elasticity, which helps to alleviate the vibration and impact from the road surface, ensure the handling stability, and make the driver feel more comfortable.

[0033] It can be understood that the connecting bolt 400 between the left front bushing 2111 and the right front bushing 3211 is a first connecting bolt, and the connecting bolt 400 between the left rear bushing 2121 and the right rear bushing 3221 is a second connecting bolt. The camber angle of the front wheel can be adjusted by adjusting the first connecting bolt. Specifically, the camber angle of the left front wheel can be adjusted by adjusting the connecting torque of the connecting bolt 400 of the left front bushing 2111, and the camber angle of the right front wheel can be adjusted by adjusting the connecting torque of the connecting bolt 400 of the right front bushing 3211. The castor angle of the front wheel can be adjusted by adjusting the second connecting bolt 400. Specifically, the kingpin inclination angle of the left rear wheel can be adjusted by adjusting the connecting torque of the connecting bolt 400 of the left rear bushing 2121, and the kingpin inclination angle of the right front wheel can be adjusted by adjusting the connecting torque of the connecting bolt 400 of the right rear bushing 3221.

[0034] Reference Figures 1 to 3As shown, the chassis also includes a stabilizer bar 700, which includes a rod body 710 and a bent section 720 connected to both ends of the rod body 710. The two longitudinal beams 110 are respectively provided with a connecting seat 130, one of which is arranged close to the left suspension structure 200, and the other connecting seat 130 is arranged close to the right suspension structure 300. The two ends of the rod body 710 are respectively rotatably connected to the two connecting seats 130, and the bent sections 720 at both ends of the rod body 710 are respectively facing the rear side of the frame 100 and are bent outward along the width direction of the frame 100. The bending section 720 at the left end of the rod body 710 is connected to the left front connecting arm 211, and the connection position of the bending section 720 at the left end is located between the left front bushing 2111 and the left steering knuckle 220; the bending section 720 at the right end of the rod body 710 is connected to the right front connecting arm 321, and the connection position of the bending section 720 at the right end is located between the right front bushing 3211 and the right steering knuckle 330. In this way, the overall strength of the stabilizer bar 700 can be improved, and a better stabilizing effect can be achieved without increasing the weight of the stabilizer bar 700.

[0035] Reference Figure 2 and Figure 3 As shown, the left and right sides of the chassis are respectively provided with a steering tie rod 800, one end of the left steering tie rod 800 is connected to the left steering knuckle 220, one end of the right steering tie rod 800 is connected to the right steering knuckle 330, and the other end of the left steering tie rod 800 is connected to the other end of the right steering tie rod 800 through a connecting rod 810. The steering tie rods 800 on both sides can ensure that the two wheels can maintain synchronous movement when turning. When the driver turns the steering wheel, the steering tie rod 800 will transfer the motion to the left and right steering knuckles 330, thereby controlling the steering of the wheels. At the same time, the steering tie rod 800 can also adjust the wheel toe angle to ensure the straight-line driving stability of the wheels.

[0036] It is understandable that the material of the frame 100 of the present embodiment can be aluminum alloy, which adopts an integral hollow casting process. This process has a higher material utilization rate than the split type and reduces welding tooling, and has a simple structural design and light weight. The cross beam 120 and the longitudinal beam 110 are respectively provided with a connection structure, and the mounting holes are respectively provided in the connection structure, so that the front bushing and the rear bushing bear the longitudinal force and the lateral force of the vehicle respectively, which can make the suspension force uniform, the strength and durability of the suspension are better, and the stability of the whole vehicle is better. In addition, in the embodiment, the left steering knuckle 220 and the right steering knuckle 330 are respectively an integrally formed structure, and the material of the left steering knuckle 220 and the right steering knuckle 330 is aluminum alloy, and the casting and forging process is used for forming. The casting and forging process can make the material present better mechanical properties, and can ensure the connection strength of the steering knuckle with the upper control arm, the lower control arm and the steering tie rod 800 and other structures.

[0037] refer to Figures 4 to 9A chassis calibration method according to an embodiment of the present invention is described, which is applied to a medium-sized bus. The chassis calibration method is explained below with a specific example.

[0038] Reference Figure 4 As shown, the chassis calibration method of a medium-sized bus in the embodiment includes but is not limited to the following steps: Step S100, before assembling the torsion bar spring 600, pre-tighten the connecting bolts 400 of the front bushing and the rear bushing to reach a first pre-tightening torque; Step S200, calibrating the eccentric gasket 500 of the front bushing and the rear bushing so that the eccentric gasket 500 is in a central position; Step S300: After the first pre-tightening torque is correct and the eccentric spacer 500 is centered, the four-wheel alignment adjustment of the vehicle is performed.

[0039] It can be understood that the left front bushing 2111 is connected to the mounting hole on the left side of the cross beam 120 through the connecting bolt 400, the left rear bushing 2121 is connected to the mounting hole on the left side of the longitudinal beam 110 through the connecting bolt 400, the right front bushing 3211 is connected to the mounting hole on the left side of the cross beam 120 through the connecting bolt 400, and the right rear bushing 3221 is connected to the mounting hole on the right side of the longitudinal beam 110 through the connecting bolt 400. Among them, the first connecting bolt and the second connecting bolt are pre-tightened before the torsion bar spring 600 is assembled to reduce and release the influence of the internal force generated by the deformation of the front bushing and the rear bushing of the lower control arm on the torsion bar spring 600. Pre-tightening can be understood as loosening the first connecting bolt and the second connecting bolt by a certain angle, and then applying a certain torque by means of a torque tool, etc., so that the first connecting bolt and the second connecting bolt are deformed to a certain extent, and the tightening force reaches a certain standard, thereby achieving the expected tightening effect. The pre-tightening operation can effectively prevent the connection bolt 400 from being deformed and loosened due to external forces during long-term operation, maintain the tightness of the connection, and make the chassis more reliable. If the first connection bolt 400 and the second connection bolt 400 are pre-tightened after the torsion bar spring 600 is assembled, the internal force generated by the deformation of the front bushing and the rear bushing will affect the torque adjustment of the torsion bar spring 600, reducing the calibration accuracy.

[0040] In some embodiments, the first connecting bolt and the second connecting bolt are pre-tightened to reach a first pre-tightening torque, the first pre-tightening torque is 100Nm, and there may be a fluctuation of ±20Nm, that is, the range of the first pre-tightening torque is 80Nm to 120Nm, so that the tightening force meets the tightness requirements of the minibus chassis. When the first pre-tightening torque meets the above range, it means that the first pre-tightening torque reaches a correct state or a qualified state. It can be understood that the maximum value of the first pre-tightening force is 120Nm and the minimum value is 80Nm, which can be adjusted according to actual application requirements.

[0041] It is understandable that the front bushing and the rear bushing have eccentric washers 500 respectively, and the alignment parameters of the wheel, such as the toe angle and the camber angle, can be adjusted by adjusting the eccentric washers 500 of the front bushing and the rear bushing, thereby affecting the handling and stability of the vehicle. After the connecting bolts 400 of the front bushing and the rear bushing are pre-tightened, the eccentric washers 500 of the front bushing and the rear bushing are corrected so that the eccentric washers 500 are in the center position, that is, the eccentric holes of the eccentric washers 500 are vertically upward, which is convenient for the subsequent four-wheel alignment of the wheel.

[0042] After the above steps S100 and S200, step S300 is performed, that is, after the first preload torque is correct and the eccentric gasket 500 is centered, the four-wheel alignment adjustment of the vehicle is performed, that is, before the four-wheel alignment, the tightening requirements of the connecting bolts 400 in the chassis subassembly process are proposed to reduce and release the internal force generated by the deformation of the front bushing and the rear bushing of the lower control arm, improve work efficiency and realize the standardization of the operation process, while reducing the accumulation of internal forces of the suspension system caused by improper operation, and can solve the deviation problem of the minibus at the lowest cost, thereby improving the driving safety of the vehicle. Among them, the purpose of the four-wheel alignment adjustment is to keep the car stable and straight and easy to steer, reduce the wear of tires and steering parts during driving, and specifically, by adjusting parameters such as kingpin castor, kingpin inclination, wheel camber and toe, the vehicle's handling, stability and safety can be optimized.

[0043] Reference Figure 5 As shown, the chassis calibration method of the medium-sized bus in the embodiment also includes but is not limited to the following steps: Step S400: After assembling the torsion bar spring 600, the torsion bar spring 600 is adjusted to reach a preset torque.

[0044] It should be noted that after the connecting bolts 400 of the front bushing and the rear bushing are pre-tightened, the two torsion bar springs 600 are assembled to the frame 100. After the torsion bar springs 600 are assembled, the torsion bar springs 600 are adjusted to reach a preset torque, which can meet the torque requirements of the minibus chassis. When the torsion bar springs 600 are torsionally deformed, sufficient resistance torque can be generated to effectively play a role in buffering and shock absorption, maintaining vehicle body stability, etc. The preset torque is set according to actual application requirements and is not specifically limited.

[0045] Step S500 , after adjusting the torsion bar spring 600 , the rod body 710 is connected to the longitudinal beam 110 , and the bent sections 720 at both ends of the rod body 710 are connected to the lower control arms of the left suspension structure 200 and the right suspension structure 300 , respectively.

[0046] It is understood that the specific connection structure of the stabilizer bar 700 can be found in the above Figures 1 to 3In the illustrated embodiment, the two longitudinal beams 110 are respectively provided with a connecting seat 130, and the two ends of the rod body 710 are rotatably connected to the two connecting seats 130 respectively. The bent section 720 at the left end of the rod body 710 is connected to the left front connecting arm 211, and the connecting position of the bent section 720 at the left end is located between the left front bushing 2111 and the left steering knuckle 220. The bent section 720 at the right end of the rod body 710 is connected to the right front connecting arm 321, and the connecting position of the bent section 720 at the right end is located between the right front bushing 3211 and the right steering knuckle 330, thereby realizing the assembly of the stabilizer bar 700. The above-mentioned connection structure can improve the overall strength of the stabilizer bar 700, and play a better stabilizing role without increasing the weight of the stabilizer bar 700.

[0047] It should be noted that the pre-tightening process of the connecting bolt 400 of the lower control arm, and the assembly sequence of the stabilizer bar 700 and the torsion bar spring 600 belong to the chassis sub-assembly process. After completing the above-mentioned chassis sub-assembly process, the embodiment of the present invention also needs to adjust the handbrake cable before the four-wheel alignment. The adjustment degree of the handbrake cable is the basis for the adjustment of the four-wheel alignment parameters. The effect of the handbrake cable adjustment is that the brake drum just cannot rotate when the handbrake is lifted, and the brake drum can rotate after the handbrake is lowered, thereby optimizing the handbrake cable adjustment, thereby reducing the sway of the vehicle caused by parking drag during the four-wheel alignment measurement process and improving the accuracy of the toe value measurement.

[0048] Reference Figure 5 As shown, in the embodiment, after the step of installing the stabilizer bar 700 is completed, the following steps are also included but not limited to: Step S600, using a level to adjust the steering wheel to the center, and after the steering wheel is adjusted to the center, determining whether the difference between the toe angles of the left wheel and the right wheel is greater than or equal to a first preset value; Step S700, when the toe angle difference is greater than or equal to the first preset value, the steering wheel is turned to make the toe angle difference less than the second preset value, and the steering wheel is reassembled, and the second preset value is less than the first preset value.

[0049] Specifically, the level is used as an auxiliary measuring tool, and the level can be a bubble level or a laser level. The level is used to measure whether the steering wheel is centered in the horizontal direction, which is easy to operate. After the steering wheel is centered, it is determined whether the difference in the toe angles of the left and right wheels is greater than or equal to a first preset value. The first preset value can be set to 3°, 5°, 8°, etc., and can be selected according to the actual application requirements of the minibus.

[0050] When the toe angle difference is greater than or equal to the first preset value, it means that the toe angle difference between the left wheel and the right wheel is large. At this time, the length of the steering tie rod 800 is not adjusted, but the steering wheel is turned to make the toe angle difference less than the second preset value. The second preset value is less than the first preset value, and the toe angle difference between the left wheel and the right wheel is as close as possible. For example, the second preset value can be 0°, 1°, etc. When the second preset value is 0, it means that the toe angles of the left wheel and the right wheel are equal. When the toe angle difference is less than the second preset value, the steering wheel is reassembled and re-centered, and the step of determining whether the toe angle difference between the left wheel and the right wheel is greater than or equal to the first preset value is repeated until the steering wheel reaches the centered position and the toe angle difference between the left wheel and the right wheel is as close as possible.

[0051] After the steering wheel is adjusted, the four-wheel alignment of the vehicle is performed, specifically adjusting the height of the chassis, adjusting the camber angle of the front wheels, adjusting the kingpin caster angle and adjusting the front wheel toe angle in sequence, which improves work efficiency and standardizes the operation process. It is also beneficial to reduce the internal force accumulation of the suspension system caused by improper operation.

[0052] Reference Figure 6 As shown in the figure, the steps of adjusting the height of the chassis in the embodiment specifically include but are not limited to the following steps: Step S800, using an auxiliary tool to measure the height of the chassis, taking the upper edge of the bracket at both sides of the auxiliary tool as a reference, adjusting the height of the chassis through the adjusting bolt 610 at the rear end of the torsion bar spring 600, so that the center of the cam bolt of the lower control arm on the front side of the chassis is aligned with the reference surface of the auxiliary tool, and the height tolerance on both sides does not exceed 1mm; Step S900, after adjusting the height of the chassis, a line is drawn on the corresponding cam bolt head based on the reference surface of the auxiliary tool to mark it, and then the mark is rechecked.

[0053] It is understood that the auxiliary tool is a measuring tool for the bracket structure. In the process of using the auxiliary tool to measure the height of the chassis, ensure that the upper edge of the bracket at the height of both sides of the auxiliary tool is the reference surface, which will be used to align a specific part of the chassis. Use the adjustment bolt 610 at the rear end of the torsion bar spring 600 to adjust the height of the chassis. This step requires careful operation to ensure that the height of the chassis meets the predetermined requirements and meets the reference standard that the center of the cam bolt of the lower control arm on the front side of the chassis is aligned with the reference surface of the auxiliary tool.

[0054] After completing the alignment, check the height tolerance on both sides of the chassis. The height tolerance on both sides should not exceed 1mm. It can be understood that the smaller the height tolerance on both sides, the closer the height values ​​on both sides of the chassis are to the design values, thereby improving the dimensional accuracy of the chassis, which has a positive impact on the vehicle's driving stability, handling and safety performance. For example, the height tolerance can be 1mm, 0.8mm, 0.5mm, etc., which ensures the stability and stability of the chassis. When the chassis height meets the requirements and the height tolerance on both sides is within the allowable range, the measurement results should be recorded and confirmed. The embodiment of the present invention proposes the requirement of left-right symmetry of the chassis height to reduce the lateral force offset of the front suspension system.

[0055] In the above step S900, after adjustment, the reference surface of the auxiliary tool is used as a reference, and a line mark is made on the corresponding cam bolt head to facilitate subsequent re-inspection. The position where the center of the rear point cam bolt of the front lower control arm of the chassis is aligned with the reference surface of the auxiliary tool can be quickly determined. Through the above steps, the chassis height auxiliary measurement control point can be proposed, and whether the vehicle height status is abnormal can be discovered in time, saving the re-inspection process, improving the measurement convenience and reducing the on-site equipment investment.

[0056] Reference Figure 7 As shown in the figure, the steps of adjusting the front wheel toe angle in the embodiment include but are not limited to the following steps: Step S1000, when the initial toe angle of the front wheel is greater than or equal to the third preset value and the value of the kingpin caster angle cannot be read, pre-adjust the toe angle of the front wheel until the value of the kingpin caster angle can be read; Step S1100, repeatedly adjusting the height of the chassis, adjusting the camber angle of the front wheels, adjusting the caster angle and adjusting the toe angle of the front wheels.

[0057] It should be noted that before adjusting the front wheel toe angle, tighten the steering wheel so that the steering wheel cannot turn, and then determine whether the initial front wheel toe angle is greater than or equal to a third preset value. The third preset value may be the maximum threshold of the front wheel toe angle, and the third preset value is adjusted to a suitable value according to the actual application requirements of the vehicle model. When the initial front wheel toe angle is greater than or equal to the third preset value, it means that the initial front wheel toe angle is too large, resulting in the inability to read the kingpin caster angle value, pre-adjust the front wheel toe angle until the kingpin caster angle value can be read, and then repeat the adjustment of the chassis height, the front wheel camber angle, the kingpin caster angle, and the front wheel toe angle to perform four-wheel alignment adjustment.

[0058] It is understandable that the left and right sides of the chassis are respectively provided with a steering tie rod 800, and the steering tie rods 800 on both sides can ensure that the two wheels can maintain synchronous movement when turning. When the driver turns the steering wheel, the steering tie rod 800 will transmit the movement to the left and right steering knuckles 330, thereby controlling the steering of the wheels. Since the steering tie rod 800 can adjust the wheel toe angle, the straight-line driving stability of the wheel is guaranteed. The steering tie rods 800 and the connecting rod 810 on both sides of the embodiment constitute a steering tie rod assembly, which can be understood as the total length of the steering tie rods 800 and the connecting rod 810 at both ends. After the step of adjusting the front wheel toe angle, by setting the assembly length of the steering tie rods 800 on both sides, the difference in assembly length is less than or equal to 3mm.

[0059] When adjusting the toe angle of the front wheels of the vehicle, ensuring that the difference in the length of the steering tie rod 800 assembly is within the above range can improve the handling and stability of the vehicle. The toe angle is adjusted to a suitable value according to the vehicle specifications and other factors. After adjusting the toe angle, it is necessary to check the length of the steering tie rod 800 and set the difference in the length of the steering tie rod 800 assembly to be less than or equal to 3mm. If the difference exceeds 3mm, it is necessary to adjust the length of the steering tie rod 800 until the difference meets the requirements.

[0060] Reference Figure 8 As shown in the figure, the steps of adjusting the front wheel camber angle and the kingpin caster angle in the embodiment specifically include but are not limited to the following steps: Step S1200, adjusting the connection torque of the connection bolt 400 of the front bushing to a range of 48Nm to 52Nm, and after the adjustment is completed, tightening the connection bolt 400 of the front bushing according to a second pre-tightening torque, the range of the second pre-tightening torque being 80Nm to 120Nm.

[0061] Step S1300, adjust the kingpin caster angle under the premise that the front wheel camber angle is qualified, adjust the connecting torque of the connecting bolt 400 of the rear bushing to the range of 48Nm to 52Nm, and after the adjustment is completed, tighten the connecting bolt 400 of the rear bushing according to the third pre-tightening torque, and the range of the third pre-tightening torque is 80Nm to 120Nm.

[0062] It should be noted that the camber angle of the front wheel should be adjusted as little as possible. If it must be adjusted, the connection torque of the front bushing connection bolt 400 can be loosened to an adjustable degree, which is approximately 50 Nm. Considering that when the front bushing connection bolt 400 is completely loosened, the camber value may jump rapidly, so it is avoided to completely loosen the front bushing connection bolt 400. After the adjustment is completed, the front bushing connection bolt 400 is tightened according to the second pre-tightening torque, and the value range of the second pre-tightening torque is 100 ± 20 Nm.

[0063] Since the large deviation of the front wheel camber angle may cause the kingpin castor angle value to be unreadable, it is necessary to adjust the kingpin castor angle under the premise of the qualified front wheel camber angle, that is, to loosen the connection torque of the rear bushing connection bolt 400 to an adjustable degree, which is about 50Nm. Considering that when the rear bushing connection bolt 400 is completely loosened, it is easy to cause the castor value to jump rapidly, so avoid completely loosening the rear bushing connection bolt 400. After the adjustment is completed, tighten the rear bushing connection bolt 400 according to the third pre-tightening torque, and the value range of the third pre-tightening torque is 100±20Nm.

[0064] It should be noted that all the connecting bolts 400 of the lower control arm are fully tightened according to the design requirements, and then the toe angle is adjusted. After the toe angle adjustment is completed, the steering tie rod 800 is tightened to adjust the nut torque, and the four-wheel alignment is re-measured, and the last measured value is saved as the final data of the vehicle.

[0065] It can be understood that the four-wheel alignment adjustment process includes chassis height adjustment accuracy, four-wheel alignment adjustment process, and pre-tightening and tightening process of camber and caster bolts, which is a key implementation approach to control deviation. The dimensional symmetry of the stabilizer bar 700 is an important object of parts quality assurance. The steps of the above-mentioned embodiment can be suitable for the chassis height measurement control points of minibus models, improve measurement convenience and reduce on-site equipment investment; and propose the requirement of left-right symmetry of chassis height to reduce the lateral force offset of the front suspension system; and by proposing the tightening process requirements of the control arm bolts at the chassis subassembly station and the four-wheel alignment station, the internal force generated by the deformation of the front suspension bushing is reduced and released; it is proposed to optimize the chassis subassembly process and the four-wheel alignment adjustment process, improve work efficiency and realize standardization of the operation process, and at the same time reduce the internal force accumulation of the suspension system caused by improper operation.

[0066] Reference Fig. 9 As shown, it is understandable that if the minibus is in a poor running state, the deviation problem cannot be solved by normal adjustment methods. In some embodiments, the following steps are used to solve the problem: Step S1400: Adjust the height of the chassis on one side of the deviation direction to be higher than the height on the other side, and the height difference between the two sides is less than or equal to 10 mm.

[0067] Specifically, the chassis height on one side of the deviation direction is adjusted to be higher than the other side, and the maximum height difference between the two sides does not exceed 10 mm. The height difference between the two sides depends on the degree of deviation. For example, the height difference between the two sides can be 5 mm, 8 mm, 10 mm, etc.

[0068] Step S1500, adjusting the caster angle of the chassis on one side of the deviation direction to be greater than the caster angle on the other side, and the difference between the caster angles on both sides is greater than or equal to 30°.

[0069] Specifically, the caster angle on one side of the deviation direction is adjusted to be greater than that on the other side, and the difference between the caster angles on both sides does not exceed 30°. The difference between the caster angles on both sides depends on the degree of deviation. For example, the difference between the caster angles on both sides can be 20°, 25°, 30°, etc. It can be understood that the above steps are countermeasures for special situations and can effectively improve deviation.

[0070] It should be noted that the present invention solves the deviation problem of minibuses at the lowest cost from the dimensions of chassis assembly process control and vehicle four-wheel alignment adjustment process control; and promotes standardized operating procedures, weakens the impact of operator differences and reduces repeated operations, improves production consistency and shortens vehicle off-line time, and can achieve a one-time pass rate of vehicle off-line dynamic inspection from 40% to more than 90%, greatly reducing rework work and ensuring the stability of production rhythm; and reduces the sensitivity of the vehicle's straight-line ability to tires, relaxes the tire taper force requirements, reduces the defective rate of tires, and saves development costs.

[0071] An embodiment of the present invention further provides a chassis tuning system, which is applicable to medium-sized buses, which may be a medium-sized bus powered by an internal combustion engine or a medium-sized bus powered by an electric motor (eg, a hybrid electric vehicle).

[0072] It should be noted that the chassis adjustment system of the medium-sized bus includes a first actuator, a second actuator and a third actuator. Among them, the first actuator is configured to pre-tighten the connecting bolts 400 of the front bushing and the rear bushing before assembling the torsion bar spring 600, and reach the first pre-tightening torque. Specifically, the first actuator can perform the above-mentioned step S100 to pre-tighten the first connecting bolt 400 and the second connecting bolt 400 before assembling the torsion bar spring 600, reduce and release the influence of the internal force generated by the deformation of the front bushing and the rear bushing of the lower control arm on the torsion bar spring 600, and the pre-tightening of the connecting bolt 400 can effectively prevent the connecting bolt 400 from being deformed and loosened due to external forces during long-term working, maintain the tightness of the connection, and make the chassis more reliable. The second actuator is configured to correct the eccentric gasket 500 of the front bushing and the rear bushing so that the eccentric gasket 500 is in a centered position. The third actuator is configured to perform four-wheel alignment adjustment on the vehicle after the first preload torque is correct and the eccentric gasket 500 is centered. Specifically, the second actuator can perform the above step S200, and the third actuator can perform the above step S300. The positioning parameters of the wheel can be adjusted by adjusting the eccentric gasket 500 of the front bushing and the rear bushing. After preloading the connecting bolts 400 of the front bushing and the rear bushing, the eccentric gasket 500 of the front bushing and the rear bushing is corrected so that the eccentric gasket 500 is centered, which is convenient for subsequent four-wheel alignment of the wheel.

[0073] Before assembling the torsion bar spring 600, the first actuator is used to pre-tighten the connecting bolts 400 of the front bushing and the rear bushing of the lower control arm and reach a first pre-tightening torque; then the eccentric gasket 500 of the front bushing and the rear bushing is corrected by the second actuator so that the eccentric gasket 500 is in a centered position, that is, the eccentric hole of the eccentric gasket 500 is vertically upward; after confirming that the first pre-tightening torque is correct and the eccentric gasket 500 is in a centered position, the third actuator is used to perform the steps of adjusting the four-wheel alignment of the vehicle, that is, before the four-wheel alignment, the tightening requirements of the connecting bolts 400 in the chassis assembly process are proposed, the internal force generated by the deformation of the front bushing and the rear bushing of the lower control arm is reduced and released, the work efficiency is improved and the operation process is standardized, while the internal force accumulation of the suspension system caused by improper operation is reduced, and the deviation problem that plagues minibuses is solved positively at the lowest cost, thereby improving the driving safety of the vehicle.

[0074] In addition, the second actuator can also perform steps such as assembly of the torsion bar spring 600 and the state of the stabilizer bar 700, such as the above-mentioned step S400, step S500, etc., and the third actuator can also perform steps of four-wheel alignment, such as the above-mentioned step S800, step S900, step S1000, step S1100, etc.

[0075] The present invention also provides a vehicle, which is a medium-sized bus, and uses the chassis calibration method of the above embodiment to calibrate the chassis of the medium-sized bus. Figures 1 to 3 The chassis tuning method can be performed as follows: Figure 4 Steps S100 to S300 of the method, Figure 5 Steps S400 to S700 of the method, Figure 6 Method steps S800 to S900, etc.

[0076] The device embodiments described above are merely illustrative, and the units described as separate components may or may not be physically separated, that is, they may be located in one place or distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0077] It should be noted that the vehicle needs to have an internal combustion engine that can output power, or an electric motor that can store mechanical energy as a generator. When the vehicle is a new energy vehicle, it can be a hybrid vehicle or a pure electric vehicle. Since the vehicle applies all the technical solutions of the above-mentioned chassis tuning method, it at least has all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be repeated here.

[0078] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of ordinary technicians in the relevant technical field without departing from the purpose of the present invention.

Claims

1. A method for adjusting the chassis of a medium-sized bus, characterized in that: The chassis comprises a frame, a left suspension structure, a right suspension structure and a torsion bar spring, the left suspension structure and the right suspension structure respectively comprise an upper control arm, a lower control arm and a steering knuckle, the upper control arm is connected between the frame and the upper part of the steering knuckle; the lower control arm comprises a front connecting arm and a rear connecting arm, the front connecting arm is provided with a front bushing, the rear connecting arm is provided with a rear bushing, one end of the front connecting arm and the rear connecting arm are connected and connected to the lower part of the steering knuckle, the other end of the front connecting arm is connected to the frame through the front bushing, the other end of the rear connecting arm is connected to the frame through the rear bushing, the front bushing and the rear bushing are respectively connected to the frame through connecting bolts, the torsion bar spring is connected to the frame, and the chassis tuning method comprises: Before assembling the torsion bar spring, pre-tightening the connecting bolts of the front bushing and the rear bushing to reach a first pre-tightening torque; Correcting the eccentric washers of the front bushing and the rear bushing so that the eccentric washers are in a centered position; After the first preload torque is correct and the eccentric gasket is centered, the four-wheel alignment adjustment of the vehicle is performed.

2. The method for adjusting the chassis of a medium-sized bus according to claim 1, characterized in that: The chassis further includes a stabilizer bar, the stabilizer bar includes a bar body and bent sections connected to both ends of the bar body, the frame includes a longitudinal beam and a cross beam connected to each other, and the chassis adjustment method includes: After assembling the torsion bar spring, adjusting the torsion bar spring to achieve a preset torque; After adjusting the torsion bar spring, the rod body is connected to the longitudinal beam, and the bent sections at both ends of the rod body are respectively connected to the lower control arms of the left suspension structure and the right suspension structure.

3. The method for adjusting the chassis of a medium-sized bus according to claim 2, characterized in that: After the stabilizer bar is installed, the method further includes: Using a level to adjust the steering wheel centering, and after the steering wheel centering, determining whether a difference in toe angles between the left wheel and the right wheel is greater than or equal to a first preset value; When the toe angle difference is greater than or equal to the first preset value, the toe angle difference is made smaller than a second preset value by rotating the steering wheel, and the steering wheel is reassembled, and the second preset value is smaller than the first preset value.

4. The method for adjusting the chassis of a medium-sized bus according to claim 1, characterized in that: The performing of adjusting the four-wheel alignment of the vehicle comprises: The height of the chassis, the camber angle of the front wheels, the caster angle and the toe angle of the front wheels are adjusted in sequence.

5. The method for adjusting the chassis of a medium-sized bus according to claim 4, characterized in that: The step of adjusting the height of the chassis comprises: The height of the chassis is measured by using an auxiliary tool, and the upper edge of the bracket at the height of both sides of the auxiliary tool is used as a reference. The height of the chassis is adjusted by the adjusting bolt at the rear end of the torsion bar spring, so that the center of the cam bolt of the lower control arm on the front side of the chassis is aligned with the reference surface of the auxiliary tool, and the height tolerance on both sides does not exceed 1mm; After adjusting the height of the chassis, a line is drawn on the corresponding cam bolt head with the reference surface of the auxiliary tool as a reference, and the mark is used for rechecking.

6. The method for adjusting the chassis of a medium-sized bus according to claim 4, characterized in that: The method of adjusting the front wheel toe angle comprises: When the initial toe angle of the front wheel is greater than or equal to the third preset value and the value of the kingpin caster angle cannot be read, pre-adjusting the toe angle of the front wheel until the value of the kingpin caster angle can be read; The adjusting of the height of the chassis, the adjusting of the camber angle of the front wheels, the adjusting of the caster angle and the adjusting of the toe angle of the front wheels are performed repeatedly in sequence.

7. The method for adjusting the chassis of a medium-sized bus according to claim 6, characterized in that: Steering tie rods are respectively provided on both sides of the chassis, the steering tie rod on one side is connected to the steering knuckle of the left suspension structure, and the steering tie rod on the other side is connected to the steering knuckle of the right suspension structure, and the two steering tie rods are connected by a connecting rod, and the method for adjusting the toe angle of the front wheel also includes: After the front wheel toe angle is adjusted, the length difference of the steering tie rod assembly on both sides is set to be less than or equal to 3 mm.

8. The method for adjusting the chassis of a medium-sized bus according to claim 4, characterized in that: The method of adjusting the front wheel camber angle comprises: The connecting torque of the connecting bolts of the front bushing is adjusted to a range of 48 Nm to 52 Nm. After the adjustment is completed, the connecting bolts of the front bushing are tightened according to a second pre-tightening torque, and the range of the second pre-tightening torque is 80 Nm to 120 Nm.

9. The method for adjusting the chassis of a medium-sized bus according to claim 4, characterized in that: The adjusting of the caster angle comprises: On the premise that the front wheel camber angle is qualified, the kingpin caster angle is adjusted, and the connecting torque of the connecting bolt of the rear bushing is adjusted to the range of 48Nm to 52Nm. After the adjustment is completed, the connecting bolt of the rear bushing is tightened according to the third pre-tightening torque, and the range of the third pre-tightening torque is 80Nm to 120Nm.

10. The method for adjusting the chassis of a medium-sized bus according to claim 1, characterized in that: The calibration method further comprises: When the medium-sized bus has a deviation problem, the height of the chassis on one side of the deviation direction is adjusted to be higher than the height on the other side, and the height difference between the two sides is less than or equal to 10 mm; The caster angle of the chassis on one side of the deviation direction is adjusted to be greater than the caster angle on the other side, and the difference between the caster angles on both sides is greater than or equal to 30°.

11. A chassis calibration system for a medium-sized bus, characterized in that: The chassis comprises a frame, a left suspension structure, a right suspension structure and a torsion bar spring, the left suspension structure and the right suspension structure respectively comprise an upper control arm, a lower control arm and a steering knuckle, the upper control arm is connected between the frame and the upper part of the steering knuckle; the lower control arm comprises a front connecting arm and a rear connecting arm, the front connecting arm is provided with a front bushing, the rear connecting arm is provided with a rear bushing, one end of the front connecting arm and the rear connecting arm are connected and connected to the lower part of the steering knuckle, the other end of the front connecting arm is connected to the frame through the front bushing, the other end of the rear connecting arm is connected to the frame through the rear bushing, the front bushing and the rear bushing are respectively connected to the frame through connecting bolts, the torsion bar spring is connected to the frame, and the chassis tuning system comprises: A first actuator is configured to pre-tighten the connecting bolts of the front bushing and the rear bushing to reach a first pre-tightening torque before assembling the torsion bar spring; A second actuator is configured to correct the eccentric washers of the front bushing and the rear bushing so that the eccentric washers are in a centered position; The third actuator is configured to perform four-wheel alignment adjustment on the vehicle after the first preload torque is correct and the eccentric spacer is centered.

12. A vehicle comprising a chassis, characterized in that: The chassis is calibrated using the chassis calibration method described in any one of claims 1 to 10.

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