Adjusting device, multi-link suspension, vehicle and method for designing a multi-link suspension

Abstract

The present application belongs to the technical field of automobile suspension, and relates to a regulating device, a multi-link suspension, a vehicle and a multi-link suspension design method. The regulating device is connected between a subframe and a longitudinal swing arm of the multi-link suspension, and comprises a regulating bolt, a regulating nut, a regulating washer and a first regulating support. The first regulating support is provided with a first arc-shaped rack and a first arc-shaped hole. The shank of the regulating bolt passes through the longitudinal swing arm, the first arc-shaped hole and the regulating washer. The regulating washer is fixed on the regulating bolt, and the outer ring of the regulating washer is provided with a gear ring engaged with the first arc-shaped rack. When the regulating nut is loosened, the regulating washer is driven to move along the first arc-shaped rack by rotating the regulating bolt, so that the shank of the regulating bolt slides along the first arc-shaped hole, and the relative position of the subframe and the longitudinal swing arm is adjusted, so as to realize the adjustment of the pitch center of the multi-link suspension. The regulating device can reduce the development time and cost of repeated production of sample parts and chassis adjustment.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of automobile suspension, in particular relates to a adjusting device, a multi-link suspension, a vehicle and a multi-link suspension design method. BACKGROUND

[0002] During acceleration or braking, due to inertia, axle load transfer will occur, accompanied by deformation of the front and rear suspensions, the vehicle body will rotate around the pitch center, and pitch motion will occur, that is, the common nodding and lifting phenomenon. During low-speed braking, in addition to the nodding phenomenon of the vehicle body, the front and rear will often move together, especially for pure electric vehicles, which seriously affects the ride comfort. Considering vehicle handling and ride comfort, it is desirable to have a smooth vehicle body motion, i.e., to reduce the pitch motion of the vehicle body and the front and rear movement. The pitch motion of the vehicle body is closely related to the overall weight, center of mass and suspension, and for the suspension, the design of the pitch center is particularly important, and the design of the pitch center of the front and rear suspensions determines the longitudinal center of the vehicle.

[0003] Five-link suspensions are widely used in mid-to-high-end vehicles due to their large design freedom, simple structure, and high integration of linkages on the rear subframe. In recent years, five-link suspensions have also been widely used in mid-to-high-end electric vehicles due to their ability to increase battery pack space. Past five-link designs have focused more on anti-nodding and longitudinal displacement changes, while pure electric vehicles have a low center of mass and a large weight due to the placement of the battery at the bottom of the vehicle. Pitch motion and front and rear movement are obvious during low-speed braking, which can easily cause user complaints about ride comfort.

[0004] In addition, for pitch motion, late-stage tuning can be optimized accordingly, which generally involves increasing the damper damping force to reduce the amount of braking nodding, but this will increase the front and rear movement and make the suspension stiffer, sacrificing comfort. Therefore, it is difficult to balance pitch motion suppression and front and rear movement suppression by simply tuning, and early matching design from the pitch center is needed.

[0005] However, in the prior art, the pitch center of the suspension is basically determined at the initial stage of project development, and repeated production of sample parts and chassis tuning is required in the later stage to meet the design requirements, increasing development time and cost. SUMMARY

[0006] The present application solves the technical problem that in the prior art, the pitch center of the suspension is basically determined at the initial stage of project development, and repeated production of sample parts and chassis tuning is required in the later stage to meet the design requirements, increasing development time and cost. The present application provides an adjusting device, a multi-link suspension, a vehicle and a multi-link suspension design method.

[0007] To solve the above technical problems, in one aspect, the present application provides an adjusting device connected between a subframe and a trailing arm of a multi-link suspension, the adjusting device comprising an adjusting bolt, an adjusting nut, an adjusting washer and a first adjusting bracket, the first adjusting bracket being fixed to the subframe and located at one side of the trailing arm;

[0008] The first adjusting bracket is provided with a first arc-shaped rack and a first arc-shaped hole, the shank of the adjusting bolt passes through the trailing arm, the first arc-shaped hole and the adjusting washer, the adjusting washer is fixed to the adjusting bolt, the adjusting nut is threadedly connected to the tail end of the adjusting bolt, and the outer ring of the adjusting washer is provided with a gear ring engaged with the first arc-shaped rack;

[0009] When the adjusting nut is tightened, the adjusting nut is pressed against the adjusting washer to temporarily fix the subframe and the trailing arm; when the adjusting nut is loosened, the adjusting washer can be driven to move along the first arc-shaped rack by rotating the adjusting bolt, so that the shank of the adjusting bolt slides along the first arc-shaped hole, thereby adjusting the relative position of the subframe and the trailing arm to achieve adjustment of the pitch center of the multi-link suspension.

[0010] Optionally, the first arc-shaped hole is in the shape of a circular arc, and the radius of the first arc-shaped hole is equal to the length of the trailing arm.

[0011] Optionally, the first adjusting bracket is further provided with a first stop wall opposite to the first arc-shaped rack, the side of the first stop wall facing the first arc-shaped rack is a first stop surface, and the gear ring is in contact with the first stop surface.

[0012] The first arc-shaped hole is located between the first stop wall and the first arc-shaped rack, and the adjusting washer is accommodated in the space defined between the first stop wall and the first arc-shaped rack.

[0013] Optionally, the first stop surface, the first arc-shaped hole and the first arc-shaped rack have the same extension direction.

[0014] Optionally, the inner hole wall of the adjusting washer protrudes towards the center to form a limiting block, the shank of the adjusting bolt is provided with a limiting groove extending in the axial direction thereof, and the limiting block is inserted into the limiting groove to limit the relative rotation of the adjusting washer and the adjusting bolt.

[0015] Optionally, two limiting blocks are provided, two limiting grooves are provided, and the two limiting blocks are arranged at intervals in the circumferential direction of the adjusting washer, each limiting block being inserted into the corresponding limiting groove.

[0016] Optionally, the adjusting device further comprises a first fixing bracket for fixing the first adjusting bracket on the sub-frame.

[0017] Optionally, a gear is fixed or integrally formed on the side of the head of the adjusting bolt towards the adjusting nut.

[0018] The adjusting device further comprises a second adjusting bracket fixed on the sub-frame and located on the other side of the trailing arm; the second adjusting bracket is provided with a second arc-shaped gear rack and a second arc-shaped hole, and the adjusting bolt passes through the second arc-shaped hole.

[0019] When the adjusting nut is loosened, the adjusting washer is driven to move along the first arc-shaped gear rack and the gear is driven to move along the second arc-shaped gear rack by rotating the adjusting bolt, so that the rod of the adjusting bolt slides along the first arc-shaped hole and the second arc-shaped hole.

[0020] Optionally, the second adjusting bracket is further provided with a second stop wall opposite to the second arc-shaped gear rack, and the side of the second stop wall towards the second arc-shaped gear rack is a second stop surface, and the gear is in contact with the second stop surface.

[0021] The second arc-shaped hole is located between the second stop wall and the second arc-shaped gear rack, and the gear is accommodated in the space defined between the second stop wall and the second arc-shaped gear rack.

[0022] Optionally, the second stop surface, the second arc-shaped hole and the second arc-shaped gear rack have the same extension direction.

[0023] Optionally, the adjusting device further comprises a second fixing bracket for fixing the second adjusting bracket on the sub-frame.

[0024] In another aspect, the embodiments of the present application further provide a multi-link suspension comprising a sub-frame, a trailing arm and the above-mentioned adjusting device.

[0025] Optionally, the multi-link suspension is a multi-link rear suspension, and the sub-frame is a rear sub-frame. For example, the multi-link suspension is a five-link rear suspension.

[0026] Optionally, the multi-link suspension further comprises a steering arm, an air spring, a toe arm, a shock absorber, a rear axle knuckle, a drive shaft, a guide arm, a stabilizer bar, a stabilizer bar pull rod and a camber arm.

[0027] The outer end of the toe arm, the guide arm and the longitudinal swing arm is connected with the rear axle joint through a bushing, the outer end of the swing arm and the camber arm is connected with the rear axle joint through a ball joint bushing, the inner end of the swing arm and the camber arm is connected with the subframe through a bushing, the upper end of the shock absorber is connected with the vehicle body through a bushing, the lower end of the shock absorber is connected with the camber arm through a bushing, the upper end of the air spring is mounted on the vehicle body longitudinal beam, the lower end of the air spring is connected with the camber arm, the stabilizer bar pull rod is connected with the guide arm, and the stabilizer bar is mounted on the subframe.

[0028] The adjusting device of the embodiment of the present application and the multi-link suspension, the adjusting device is connected between the subframe and the longitudinal swing arm of the multi-link suspension, the adjusting device comprises an adjusting bolt, an adjusting nut, an adjusting washer and a first adjusting bracket, the first adjusting bracket is fixed on the subframe and located on one side of the longitudinal swing arm. The first adjusting bracket is provided with a first arc-shaped rack and a first arc-shaped hole, the rod part of the adjusting bolt passes through the longitudinal swing arm, the first arc-shaped hole and the adjusting washer, the adjusting washer is fixed on the adjusting bolt, the adjusting nut is threadedly connected at the tail end of the adjusting bolt, and the outer ring of the adjusting washer is provided with a gear ring engaged with the first arc-shaped rack. During the chassis tuning stage, the adjusting nut is loosened, the adjusting washer is driven to move along the first arc-shaped rack by rotating the adjusting bolt, so that the rod part of the adjusting bolt slides along the first arc-shaped hole, and the relative position of the subframe and the longitudinal swing arm is adjusted, so as to realize the adjustment of the pitch center of the multi-link suspension. In this way, means for subsequent chassis tuning is added, and the contradiction between low-speed active body nodding and front-rear movement is more comprehensively balanced without increasing the tuning sample and cost, so that the balance of vehicle handling stability and smoothness is achieved, and the vehicle performance is improved. Moreover, by reasonably designing the adjusting device, a reasonable variable range of the pitch center of the multi-link suspension can be matched at the early stage of project development, and the wheel attitude is ensured unchanged, the development time and cost of repeated sample making and chassis tuning in the later stage are reduced, and the accuracy and efficiency of automobile development and design are improved.

[0029] In another aspect, the embodiment of the present application further provides a vehicle comprising the above-mentioned multi-link suspension.

[0030] In another aspect, the embodiment of the present application further provides a multi-link suspension design method based on the above-mentioned multi-link suspension, comprising:

[0031] A differential equation of dynamic motion of body braking pitching is established, and the body pitching angle and the longitudinal displacement are solved;

[0032] A braking nodding mechanical equation is established to represent the relationship between the pitch center height and the body pitching;

[0033] According to the hard points of the multi-link suspension, a pitch center motion equation of the multi-link suspension is established;

[0034] According to the pitch center motion equation of the multi-link suspension, the relationship between the movement displacement of the adjusting bolt and the pitch center is obtained.

[0035] The relationship between the movement displacement of the adjusting bolt and the body pitching and the front and rear movement is obtained.

[0036] According to the movement displacement of the adjusting bolt, the structural size of the first arc-shaped hole is designed.

[0037] Optionally, the multi-link suspension is a five-link suspension, and the body braking pitching dynamics motion differential equation is established, including:

[0038] The five-degree-of-freedom body braking pitching dynamics motion differential equation is established.

[0039] Optionally, the five-degree-of-freedom body braking pitching dynamics motion differential equation is represented by the following formula:

[0040]

[0041] wherein, ∑M yz represents the pitching moment generated by the vertical suspension force, and is represented by the following formula:

[0042] ∑M yz = -L f S zf + L r S zr (2) ; S zf represents the front suspension vertical force, S zr represents the rear suspension vertical force, L f represents the distance between the pitch center and the front axle, L r represents the distance between the pitch center and the rear axle.

[0043] ∑M yt represents the pitching moment generated by the braking force, and is represented by the following formula:

[0044] ∑M yt = h g (F xf +F xr ) (3) ; h g represents the height of the center of mass, F xf represents the front axle load of the whole vehicle, F xr represents the rear axle load of the whole vehicle.

[0045] ∑M yg represents the pitching moment generated by the gravity, and is represented by the following formula:

[0046] ∑M yg = m s gh d sinθ (4) ; m swherein m represents the mass of the sprung mass, g represents the acceleration of gravity, h d wherein ΔH represents the height difference between the pitch center and the center of mass, and θ represents the vehicle body pitch angle.

[0047] Optionally, the establishing of the braking head-up mechanical equation comprises:

[0048] The actual front suspension head-up angle equation and the actual rear suspension head-up angle equation are respectively established.

[0049] Optionally, the actual front suspension head-up angle equation is represented by the following formula:

[0050] tan θ f = H / (βL) (5); θ f wherein θ represents the actual front suspension head-up angle, H represents the center of mass height, β represents the front braking force distribution coefficient, and L represents the wheelbase;

[0051] The actual rear suspension head-up angle equation is represented by the following formula:

[0052] tan θ r = H / ((1-β)L) (6); θ r wherein θ represents the actual rear suspension head-up angle.

[0053] Optionally, the method further comprises:

[0054] comparing the actual front suspension head-up angle θ f with the ideal front suspension head-up angle θ fi , comparing the actual rear suspension head-up angle θ r with the ideal rear suspension head-up angle θ ri ; specifically:

[0055] when tan θ f > tan θ fi and tan θ r > tan θ ri , the actual pitch center height is greater than the center of mass height H, and the pitch moment My during braking causes the head-up phenomenon;

[0056] when tan θ f = tan θ fi and tan θ r = tan θ ri , the actual pitch center height is equal to the center of mass height H, and ΔH = 0, the pitch is not deformed;

[0057] in other cases, the actual pitch center height is less than the center of mass height H, and ΔH is not 0, and the braking pitch moment causes the head-down phenomenon.

[0058] Optionally, the establishing of the multi-link suspension pitch center motion equation comprises:

[0059] The virtual swing arm length equation is established.

[0060] The virtual swing arm angle equation is established.

[0061] Optionally, the virtual swing arm length equation is represented by the following formula:

[0062] Lsw = (DX 2 + DZ 2 ) ∧ 0.5 / Dφ (7); DX represents the wheel center longitudinal displacement change, DZ represents the wheel center vertical displacement change, and Dφ represents the wheel center rotation angle change;

[0063] The virtual swing arm degree equation is represented by the following formula:

[0064] Dφ = atan (DX / DZ) (8).

[0065] Optionally, the relationship between the movement displacement of the adjusting bolt and the pitch center is obtained, including:

[0066] The adjusting bolt is set as the inner point of the longitudinal swing arm, the length of the longitudinal swing arm is kept unchanged, and the toe camber angle is kept unchanged, the vertical height difference Δh of the point on the circular arc of the first arc-shaped hole and the design position hard point is taken as a variable, and the relationship between the virtual swing arm length L SW , the virtual swing arm angle φ and the vertical height difference Δh is obtained; represented by the following formula:

[0067] φ = f (Δh) (9);

[0068] L SW = g (Δh) (10);

[0069] The height h v of the pitch center is calculated; represented by the following formula:

[0070] h v = L SW sin (φ) + R (11); R represents the tire static radius.

[0071] Optionally, the relationship between the adjustable movement mechanism displacement and the vehicle body pitch and front and rear movement is obtained, including:

[0072] The relationship between the movement displacement Δh of the adjusting bolt and the vehicle body longitudinal displacement x is solved by combining formulas (9)-(11) as follows:

[0073] θ = f1 (Δh) (12);

[0074] x = f2 (Δh) (13);

[0075] Wherein, the height difference h d = h g -h v between the mass center and the pitch center.

[0076] Optionally, according to the motion displacement of the adjusting bolt, the structural size of the first arc-shaped hole comprises:

[0077] The first arc-shaped hole is determined as a circular arc, and a circular arc radius is a length of the longitudinal swing arm;

[0078] A planar geometric equation of the adjusting bolt is established as follows:

[0079] L tr 2 =(Δh) 2 +(L tr -ΔL) 2 (14);

[0080] Wherein, L tr is the length of the longitudinal swing arm, Δh is the motion displacement of the adjusting bolt, O1 is an inner point of the longitudinal swing arm, O2 is an outer point of the longitudinal swing arm, and Q is a hard point of the adjusting bolt;

[0081] The up and down adjustment range of the adjusting bolt is determined according to the planar geometric equation.

[0082] Optionally, the up and down adjustment range of the adjusting bolt is-20mm-20mm according to the planar geometric equation, and the height adjustment range of the trim center is-30mm-30mm.

[0083] Optionally, after the structural size of the first arc-shaped hole is designed according to the motion displacement of the adjusting bolt, the method further comprises:

[0084] An ADAMS model containing the adjusting device is established, low-speed braking simulation is carried out, and the contradiction between the braking nodding and the front and rear movement is optimized, so that the performance matching in the early stage of design and the performance prediction in the later stage of adjustment are realized. BRIEF DESCRIPTION OF DRAWINGS

[0085] Figure 1 is a schematic diagram of a multi-link suspension provided by an embodiment of the present application;

[0086] Figure 2 is an assembly diagram of the adjusting device, the subframe and the longitudinal swing arm of the multi-link suspension provided by an embodiment of the present application;

[0087] Figure 3 is a local enlarged view of the adjusting device position in Figure 2 ;

[0088] Figure 4 is a schematic diagram of the adjusting bolt of the adjusting device provided by an embodiment of the present application;

[0089] Figure 5 is a schematic diagram of the first adjusting support of the adjusting device provided by an embodiment of the present application;

[0090] Figure 6is a schematic view of an adjusting washer of an adjusting device provided by an embodiment of the present application;

[0091] Figure 7 is a flow chart of a multi-link suspension design method provided by an embodiment of the present application;

[0092] Figure 8 is a parameter schematic view of establishing a body braking pitching dynamics motion differential equation of a multi-link suspension design method provided by an embodiment of the present application;

[0093] Figure 9 is a parameter schematic view of establishing a braking nodding mechanical equation of a multi-link suspension design method provided by an embodiment of the present application;

[0094] Figure 10 is a parameter schematic view of establishing a multi-link suspension trim center motion equation of a multi-link suspension design method provided by an embodiment of the present application;

[0095] Figure 11 is a parameter schematic view of establishing a plane in geometry equation of an adjusting bolt of a multi-link suspension design method provided by an embodiment of the present application.

[0096] The reference signs in the specification are as follows:

[0097] 1. subframe;

[0098] 2. longitudinal swing arm;

[0099] 3. adjusting device;31, adjusting bolt;311, limiting groove;312, gear;32, adjusting nut;33, adjusting washer;331, gear ring;332, limiting block;34, first adjusting support;341, first arc-shaped rack;342, first arc-shaped hole;343, first stop wall;3431, first stop surface;35, first fixed support;36, second adjusting support;361, second arc-shaped rack;362, second stop wall;37, second fixed support.

[0100] 4. swing arm;5, air spring;6, toe arm;7, shock absorber;8, rear axle joint;9, transmission shaft;10, guide arm;20, stabilizer bar;30, stabilizer bar pull rod;40, camber arm. DETAILED DESCRIPTION

[0101] In order to make the technical problems solved by the present application, technical solutions and beneficial effects clearer, the following combines the drawings and examples to make the present application further detailed. It should be understood that the specific examples described herein are only used to explain the present application, and are not used to limit the present application.

[0102] Referring to Figures 1 to 6The embodiment of the present application provides a multi-link suspension, which comprises a subframe 1, a longitudinal swing arm 2 and an adjusting device 3, the adjusting device 3 is connected between the subframe 1 and the longitudinal swing arm 2, the adjusting device 3 comprises an adjusting bolt 31, an adjusting nut 32, an adjusting washer 33 and a first adjusting bracket 34, the first adjusting bracket 34 is fixed on the subframe 1 and located on one side of the longitudinal swing arm 2, a first arc-shaped gear rack 341 and a first arc-shaped hole 342 are arranged on the first adjusting bracket 34, the rod part of the adjusting bolt 31 penetrates through the longitudinal swing arm 2, the first arc-shaped hole 342 and the adjusting washer 33, the adjusting washer 33 is fixed on the adjusting bolt 31, the adjusting nut 32 is threadedly connected to the tail end of the adjusting bolt 31, and the outer ring of the adjusting washer 33 is provided with a gear ring 331 which is engaged with the first arc-shaped gear rack 341.

[0103] When the adjusting nut 32 is tightened, the adjusting nut 32 is pressed on the adjusting washer 33 to temporarily fix the subframe 1 and the longitudinal swing arm 2, and when the adjusting nut 32 is loosened, the adjusting washer 32 can be driven to move along the first arc-shaped gear rack 341 by rotating the adjusting bolt 31, so that the rod part of the adjusting bolt 31 slides along the first arc-shaped hole 342, thereby adjusting the relative position of the subframe 1 and the longitudinal swing arm 2 to realize the adjustment of the pitch center of the multi-link suspension.

[0104] In an embodiment, the first arc-shaped hole 342 is in a circular arc shape, and the radius of the first arc-shaped hole 342 is the length of the longitudinal swing arm 2.

[0105] In an embodiment, referring to Figure 3 and Figure 5 , the first adjusting bracket 34 is further provided with a first stop wall 343 opposite to the first arc-shaped gear rack 341, the side of the first stop wall 343 facing the first arc-shaped gear rack 341 is a first stop surface 3431, and the gear ring 331 is in contact with the first stop surface 3431. The first arc-shaped hole 342 is located between the first stop wall 343 and the first arc-shaped gear rack 341, and the adjusting washer 33 is contained in the space defined between the first stop wall 343 and the first arc-shaped gear rack 341. In this way, the internal space of the first adjusting bracket 34 is reasonably utilized to contain the adjusting washer 33, so as to reduce the volume of the adjusting device.

[0106] In an embodiment, referring to Figure 3 and Figure 5 , the first stop surface 3431, the first arc-shaped hole 342 and the first arc-shaped gear rack 341 are in the same extension direction. In this way, the movement of the adjusting washer 33 is not easy to be stuck.

[0107] In an embodiment, referring to Figure 4 andFigure 6 The inner hole wall of the adjusting washer 33 is protruded to the center to form a limiting block 332, and the outer periphery of the rod of the adjusting bolt 31 is provided with a limiting slot 311 extending along the axial direction, and the limiting block 332 is inserted into the limiting slot 311 to limit the relative rotation between the adjusting washer 33 and the adjusting bolt 31.

[0108] In an embodiment, two limiting blocks 332 are provided, and two limiting slots 311 are provided, and the two limiting blocks 332 are arranged at intervals in the circumferential direction of the adjusting washer 33, and each limiting block 332 is inserted into the corresponding limiting slot 311. By arranging the two sets of limiting blocks 332 and limiting slots 311 at intervals in the circumferential direction, the connection between the adjusting washer 33 and the adjusting bolt 31 can be more stable.

[0109] In an embodiment, referring to Figure 3 The adjusting device further comprises a first fixing bracket 35 for fixing the first adjusting bracket 34 on the auxiliary frame 1.

[0110] In an embodiment, referring to Figure 3 and Figure 4 The head of the adjusting bolt 31 is fixed or integrally formed with a gear 312 on the side facing the adjusting nut 32; the adjusting device further comprises a second adjusting bracket 36 fixed on the auxiliary frame 1 and located on the other side of the longitudinal swing arm 2; the second adjusting bracket 36 is provided with a second arc-shaped gear rack 361 and a second arc-shaped hole, and the adjusting bolt 31 passes through the second arc-shaped hole. The second adjusting bracket 36 is symmetrically arranged with the first adjusting bracket 34.

[0111] When the adjusting nut 32 is loosened, the adjusting washer 33 can be driven to move along the first arc-shaped gear rack 341 and the gear 312 can be driven to move along the second arc-shaped gear rack 361 by rotating the adjusting bolt 31, so that the rod of the adjusting bolt 31 slides along the first arc-shaped hole 342 and the second arc-shaped hole. In this way, both ends of the length direction of the adjusting bolt 31 can be supported to improve the stability of movement and improve the adjustment accuracy.

[0112] In an embodiment, referring to Figure 3 The second adjusting bracket 36 is further provided with a second stop wall 362 opposite to the second arc-shaped gear rack 361, the side of the second stop wall 362 facing the second arc-shaped gear rack is a second stop surface, the gear 312 is in contact with the second stop surface; the second arc-shaped hole is located between the second stop wall 362 and the second arc-shaped gear rack 361, and the gear 312 is accommodated in the space defined between the second stop wall 362 and the second arc-shaped gear rack 361.

[0113] In an embodiment, the second stop surface, the second arc-shaped hole and the second arc-shaped rack 361 are in the same direction of extension. In this way, the movement of the gear 312 is not easily stuck.

[0114] In an embodiment, the adjusting device further comprises a second fixing bracket 37 for fixing the second adjusting bracket 36 on the subframe 1.

[0115] In an embodiment, referring to Figure 1 , the multi-link suspension is a multi-link rear suspension, and the subframe is a rear subframe. For example, the multi-link suspension is a five-link rear suspension. The multi-link suspension further comprises a toe arm 6, an air spring 5, a toe arm 6, a shock absorber 7, a rear axle knuckle 8, a drive shaft 9, a guide arm 10, a stabilizer bar 20, a stabilizer bar pull rod 30 and a camber arm 40; the outer end of the toe arm 6, the guide arm 10 and the toe arm 2 is connected to the rear axle knuckle 8 through a bushing, the outer end of the toe arm 4 and the camber arm 40 is connected to the rear axle knuckle 8 through a ball joint bushing, the inner end of the toe arm 4 and the camber arm 40 is connected to the subframe 1 through a bushing, the upper end of the shock absorber 7 is connected to the vehicle body through a bushing, the lower end of the shock absorber 7 is connected to the camber arm 40 through a bushing, the upper end of the air spring 5 is mounted on the vehicle body longitudinal beam, the lower end of the air spring 5 is connected to the camber arm 40, the stabilizer bar pull rod 30 is connected to the guide arm 10, and the stabilizer bar 20 is mounted on the subframe 1.

[0116] Referring to Figure 1 , the multi-link suspension comprises a subframe 1 and a left-right symmetrical two-side suspension structure, and each side suspension structure comprises a toe arm 2, an adjusting device 3, a toe arm 4, an air spring 5, a toe arm 6, a shock absorber 7, a rear axle knuckle 8, a drive shaft 9, a guide arm 10, a stabilizer bar 20, a stabilizer bar pull rod 30 and a camber arm 40.

[0117] The adjusting device and the multi-link suspension of the embodiment of the present application can drive the adjusting washer 33 to move along the first arc-shaped rack 341 by rotating the adjusting bolt 31 to make the rod part of the adjusting bolt 31 slide along the first arc-shaped hole 342, thereby adjusting the relative position of the auxiliary frame 1 and the longitudinal swing arm 2 to realize the adjustment of the pitch center of the multi-link suspension. In this way, the subsequent chassis adjustment can be increased, the contradiction between the low-speed active body nodding and the front and rear movement can be more comprehensively balanced without increasing the adjustment sample and the cost, the balance of the vehicle handling stability and the smoothness can be achieved, and the vehicle performance can be improved. Moreover, by reasonably designing the adjusting device, the reasonable variable range of the pitch center of the multi-link suspension can be matched in the early stage of the project development, and the wheel posture can be ensured unchanged, the development time and the cost of the repeated sample production and the chassis adjustment in the later stage can be reduced, and the accuracy and the efficiency of the automobile development design can be improved.

[0118] Referring to Figure 7 The embodiment of the present application also provides a multi-link suspension design method based on the above multi-link suspension, which comprises the following steps:

[0119] A body braking pitching dynamics differential equation is established to solve the body pitching angle and the longitudinal displacement;

[0120] A braking nodding mechanical equation is established to represent the relationship between the pitch center height and the body pitching;

[0121] According to the hard points of the multi-link suspension, a multi-link suspension pitch center motion equation is established;

[0122] According to the multi-link suspension pitch center motion equation, the relationship between the motion displacement of the adjusting bolt and the pitch center is solved;

[0123] The relationship between the motion displacement of the adjusting bolt and the body pitching and the front and rear movement is solved;

[0124] According to the motion displacement of the adjusting bolt, the structural size of the first arc-shaped hole is designed.

[0125] In an embodiment, the multi-link suspension is a five-link suspension, and the establishment of the body braking pitching dynamics differential equation comprises the following steps:

[0126] A five-degree-of-freedom body braking pitching dynamics differential equation is established.

[0127] Referring to Figure 8 In an embodiment, the five-degree-of-freedom body braking pitching dynamics differential equation is represented by the following formula:

[0128]

[0129] Where, ∑M yzrepresents the pitch moment generated by the front suspension vertical force, and is represented by the following equation:

[0130] ∑M yz = -L f S zf +L r S zr (2) ; S zf represents the front suspension vertical force, S zr represents the rear suspension vertical force, L f represents the distance between the center of gravity and the front axle, L r represents the distance between the center of gravity and the rear axle;

[0131] ∑M yt represents the pitch moment generated by the braking force, and is represented by the following equation:

[0132] ∑M yt = h g (F xf +F xr ) (3) ; h g represents the height of the center of gravity, F xf represents the front axle load of the vehicle, F xr represents the rear axle load of the vehicle;

[0133] ∑M yg represents the pitch moment generated by the gravity, and is represented by the following equation:

[0134] ∑M yg = m s gh d sin θ (4) ; m s represents the sprung mass, g represents the gravity acceleration, h d represents the height difference between the center of gravity and the center of mass, and θ represents the pitch angle of the vehicle body.

[0135] The vehicle longitudinal rigid body dynamics motion differential equation is represented by the following equation:

[0136] ma x = -F xf -F xr (1A) ; wherein, is the total longitudinal acceleration, including the longitudinal acceleration and the acceleration caused by the pitch and the vertical.

[0137] The sprung mass vertical dynamics motion differential equation is represented by the following equation,

[0138] m s a z = S zf +S zr (1B) ; wherein, is the total vertical acceleration, respectively, are front and rear suspension vertical forces.

[0139] Equation (1) can be obtained from Equation (1A) and Equation (1B).

[0140] In an embodiment, establishing the braking head-up mechanical equation comprises:

[0141] The front suspension actual head-up resistance angle equation and the rear suspension actual head-up resistance angle equation are respectively established.

[0142] In an embodiment, referring to Figure 9 , the front suspension actual head-up resistance angle equation is expressed as:

[0143] tanθ f = H / (βL) (5); θ f represents the actual front suspension head-up resistance angle, H represents the center of mass height, β represents the front braking force distribution coefficient, and L represents the wheelbase;

[0144] The rear suspension actual head-up resistance angle equation is expressed as:

[0145] tanθ r = H / ((1-β)L) (6); θ r represents the actual rear suspension head-up resistance angle.

[0146] Figure 9 , G represents the center of mass, L represents the wheelbase (a+b), H represents the center of mass height, H i represents the ideal pitch center height, P represents the pitch center, P i represents the ideal pitch center, β represents the front braking force distribution coefficient, E1 and E2 represent longitudinal equivalent swing arm centroids (virtual hinge points), θ fi , θ ri represent ideal front and rear suspension head-up resistance angles, θ f , θ r represent actual front and rear head-up resistance angles.

[0147] In an embodiment, the method further comprises:

[0148] Comparing the actual front suspension head-up resistance angle θ f with the ideal front suspension head-up resistance angle θ fi , comparing the actual rear suspension head-up resistance angle θ r with the ideal rear suspension head-up resistance angle θ ri ; specifically:

[0149] When tanθ f > tanθ fi and tanθ r > tanθ ri , the actual pitch center height is greater than the center of mass height H, and the pitch moment My during braking causes the head-up phenomenon;

[0150] When tanθ f = tanθ fi and tanθ r = tanθ ri , the actual pitch center height is equal to the mass center height H, ΔH = 0, and the pitch is not deformed;

[0151] In other cases, the actual pitch center height is less than the mass center height H, ΔH ≠ 0, and the braking pitch moment causes the nodding phenomenon.

[0152] Referring to Figure 10 , in an embodiment, establishing the pitch center motion equation of the multi-link suspension includes:

[0153] establishing a virtual swing arm length equation;

[0154] establishing a virtual swing arm angle equation.

[0155] Optionally, the virtual swing arm length equation is represented by the following formula:

[0156] Lsw= (DX 2 +DZ 2 )∧0.5 / Dφ (7);DX represents the change in longitudinal displacement of the wheel center, DZ represents the change in vertical displacement of the wheel center, and Dφ represents the change in rotation angle of the wheel center;

[0157] The virtual swing arm angle equation is represented by the following formula:

[0158] Dφ=atan(DX / DZ) (8)。

[0159] In an embodiment, obtaining the relationship between the motion displacement of the adjusting bolt and the pitch center includes:

[0160] Setting the adjusting bolt as an inner point of the longitudinal swing arm, keeping the length of the longitudinal swing arm unchanged and the toe angle unchanged, taking the vertical height difference Δh between the upper point of the first arc-shaped hole and the designed position hard point as a variable, obtaining the relationship between the virtual swing arm length L SW , the virtual swing arm angle φ and the vertical height difference Δh; represented by the following formula:

[0161] φ=f(Δh) (9);

[0162] L SW =g(Δh) (10);

[0163] calculating the height h v of the pitch center; represented by the following formula:

[0164] h v =L SW sin(φ)+R (11);R represents the static radius of the tire.

[0165] In an embodiment, the relationship between the displacement of the adjustable motion mechanism and the pitch and fore-aft movement of the vehicle body is obtained as follows:

[0166] The relationship between the displacement of the adjusting bolt and the longitudinal displacement of the vehicle body is obtained according to the equations (9)-(11) as follows:

[0167] θ = f1(Δh) (12);

[0168] x = f2(Δh) (13);

[0169] wherein the height difference between the center of mass and the pitch center h d = h g -h v .

[0170] Referring to Figure 11 In an embodiment, the structural size of the first arc-shaped hole is designed according to the displacement of the adjusting bolt as follows:

[0171] The first arc-shaped hole is determined to be a circular arc, and the radius of the circular arc is the length of the longitudinal swing arm;

[0172] The in-plane geometric equation of the adjusting bolt is established as follows:

[0173] L tr 2 = (Δh) 2 +(L tr -ΔL) 2 (14);

[0174] wherein L tr is the length of the longitudinal swing arm, Δh is the displacement of the adjusting bolt, O1 is the inner point of the longitudinal swing arm, O2 is the outer point of the longitudinal swing arm, and Q is the hard point of the adjusting bolt;

[0175] The up and down adjustment range of the adjusting bolt is determined according to the above in-plane geometric equation.

[0176] In an embodiment, the up and down adjustment range of the adjusting bolt is determined to be -20mm-20mm according to the above in-plane geometric equation, and the height adjustment range of the pitch center is -30mm-30mm.

[0177] The adjusting device adjusts the gear on the adjusting bolt to mesh with the second arc-shaped gear rack of the second adjusting support, and the gear ring on the adjusting washer to mesh with the first arc-shaped gear rack on the first adjusting support, and the adjusting bolt is inserted into the first arc-shaped hole on the first adjusting support and the second arc-shaped hole on the second adjusting support. By rotating the head of the adjusting bolt, the gear on the adjusting bolt and the gear ring on the adjusting washer are rotated, so that the adjusting bolt moves along the designed arc line (determined by the first arc-shaped hole), so as to achieve the relationship between the motion displacement and the longitudinal center x=f2(Δh), and realize the purpose of adjusting the longitudinal center.

[0178] In an embodiment, after the structure size of the first arc-shaped hole is designed according to the motion displacement of the adjusting bolt, the following steps are further included:

[0179] An ADAMS model containing the adjusting device is established, low-speed braking simulation is carried out, and the contradiction between braking head and front-back movement is optimized, so as to perform performance matching in the early stage and performance prediction in the later stage.

[0180] The multi-link suspension design method of the embodiment of the present application establishes a longitudinal and vertical combined dynamics motion equation (a body braking pitching dynamics motion differential equation) in the braking process. Compared with the current consideration of only a single performance target, the body pitching and front-back movement can be designed and analyzed in the design stage, and the risk of unacceptable performance caused by repeated design in the later stage or even the design that cannot be changed in the later stage is reduced.

[0181] In addition, the longitudinal center adjustable displacement mechanism (adjusting device) is designed, which can provide an effective means for later chassis tuning, and the real vehicle tuning is confirmed according to the design result, so as to balance and optimize the body pitching and front-back movement performance.

[0182] In addition, the longitudinal center adjustable displacement mechanism (adjusting device) has a simple structure and is easy to realize, and can be customized according to the demand, and the relationship between the longitudinal center adjustable displacement mechanism and the performance is quantified, so as to save the cost of tuning samples and improve the verification efficiency of tuning.

[0183] In addition, the embodiment of the present application also provides a vehicle comprising the multi-link suspension of the above-mentioned embodiment.

[0184] The above only describes the preferred embodiments of the present application and is not intended to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An adjusting device, characterized in that The adjusting device is connected between the auxiliary frame and the trailing arm of the multi-link suspension, and comprises an adjusting bolt, an adjusting nut, an adjusting washer and a first adjusting support fixed to the auxiliary frame and located at one side of the trailing arm; The first adjusting support is provided with a first arc-shaped rack and a first arc-shaped hole, the rod of the adjusting bolt passes through the trailing arm, the first arc-shaped hole and the adjusting washer, the adjusting washer is fixed to the adjusting bolt, the adjusting nut is threadedly connected to the tail end of the adjusting bolt, and the outer ring of the adjusting washer is provided with a gear ring engaged with the first arc-shaped rack; When the adjusting nut is tightened, the adjusting nut is pressed on the adjusting washer to temporarily fix the auxiliary frame and the trailing arm; when the adjusting nut is loosened, the adjusting washer can be driven to move along the first arc-shaped rack by rotating the adjusting bolt, so that the rod of the adjusting bolt slides along the first arc-shaped hole, thereby adjusting the relative position of the auxiliary frame and the trailing arm to achieve adjustment of the pitch center of the multi-link suspension; The first arc-shaped hole is in the shape of a circular arc; The adjusting device further comprises a first fixing support for fixing the first adjusting support to the auxiliary frame.

2. The adjustment device of claim 1, wherein The radius of the first arc-shaped hole is equal to the length of the trailing arm.

3. The adjustment device of claim 1, wherein, The first adjusting support is further provided with a first stop wall opposite to the first arc-shaped rack, the side of the first stop wall facing the first arc-shaped rack is a first stop surface, and the gear ring is in contact with the first stop surface; The first arc-shaped hole is located between the first stop wall and the first arc-shaped rack, and the adjusting washer is accommodated in the space defined between the first stop wall and the first arc-shaped rack.

4. The adjustment device of claim 3, wherein The first stop surface, the first arc-shaped hole and the first arc-shaped rack have the same extension direction.

5. The adjustment device of claim 1, wherein, The inner hole wall of the adjusting washer protrudes towards the center to form a limiting block, the outer periphery of the rod of the adjusting bolt is provided with a limiting groove extending in the axial direction, and the limiting block is inserted into the limiting groove to limit the relative rotation of the adjusting washer and the adjusting bolt.

6. The adjustment device of claim 5, wherein, The limiting block is provided with two limiting grooves, and the two limiting blocks are arranged at intervals in the circumferential direction of the adjusting washer, and each limiting block is inserted into the corresponding limiting groove.

7. The adjustment device according to any one of claims 1 to 6, characterized in that The head of the adjusting bolt is fixed or integrally formed with a gear on the side facing the adjusting nut; The adjusting device further comprises a second adjusting support fixed to the auxiliary frame and located at the other side of the trailing arm, the second adjusting support is provided with a second arc-shaped rack and a second arc-shaped hole, and the adjusting bolt passes through the second arc-shaped hole; When the adjusting nut is loosened, the adjusting washer can be driven to move along the first arc-shaped rack and the gear can move along the second arc-shaped rack by rotating the adjusting bolt, so that the rod of the adjusting bolt slides along the first arc-shaped hole and the second arc-shaped hole.

8. The adjustment device of claim 7, wherein, The second adjusting support is further provided with a second stop wall opposite to the second arc-shaped rack, a side of the second stop wall facing the second arc-shaped rack is a second stop surface, and the gear is in contact with the second stop surface; The second arc-shaped hole is located between the second stop wall and the second arc-shaped rack, and the gear is contained in a space defined between the second stop wall and the second arc-shaped rack.

9. The adjustment device of claim 8, wherein, The second stop surface, the second arc-shaped hole and the second arc-shaped rack have a same extension direction.

10. The adjustment device of claim 7, wherein, The adjusting device further comprises a second fixing support for fixing the second adjusting support on the sub-frame.

11. A multi-link suspension characterized in that, The adjusting device comprises a sub-frame, a longitudinal swing arm and the adjusting device according to any one of claims 1-10.

12. The multi-link suspension of claim 11, wherein, The multi-link suspension is a multi-link rear suspension, and the sub-frame is a rear sub-frame.

13. The multi-link suspension of claim 12, wherein, The multi-link suspension further comprises a swing arm, an air spring, a toe arm, a shock absorber, a rear axle joint, a transmission shaft, a guide arm, a stabilizer bar, a stabilizer bar pull rod and a camber arm. Outer ends of the toe arm, the guide arm and the longitudinal swing arm are connected to the rear axle joint through a bushing, outer ends of the swing arm and the camber arm are connected to the rear axle joint through a spherical hinge bushing, inner ends of the swing arm and the camber arm are connected to the sub-frame through a bushing, an upper end of the shock absorber is connected to a vehicle body through a bushing, a lower end of the shock absorber is connected to the camber arm through a bushing, an upper end of the air spring is mounted on a vehicle body longitudinal beam, a lower end of the air spring is connected to the camber arm, the stabilizer bar pull rod is connected to the guide arm, and the stabilizer bar is mounted on the sub-frame.

14. A vehicle characterized by comprising: The multi-link suspension comprises the multi-link suspension according to any one of claims 11-13.

15. A method of designing a multi-link suspension based on the multi-link suspension of any one of claims 11-13, characterized by, The method comprises: A differential equation of body braking pitch dynamics is established, and a body pitch angle and a longitudinal displacement are solved; A braking nodding mechanical equation is established to represent a relationship between a height of a center of gravity and the body pitch; A center of gravity motion equation of the multi-link suspension is established according to hard points of the multi-link suspension; A relationship between a motion displacement of the adjusting bolt and the center of gravity is solved according to the center of gravity motion equation of the multi-link suspension; A relationship between the motion displacement of the adjusting bolt and the body pitch and the front and rear displacement is solved; A structure size of the first arc-shaped hole is designed according to the motion displacement of the adjusting bolt.

16. The multi-link suspension design method of claim 15, wherein, The multi-link suspension is a five-link suspension, and the establishing of the differential equation of body braking pitch dynamics comprises: A differential equation of five-degree-of-freedom body braking pitch dynamics is established.

17. The multi-link suspension design method of claim 16, wherein, The differential equation of five-degree-of-freedom body braking pitch dynamics is represented by the following formula: （1）； wherein represents the pitch moment generated by the vertical suspension force, and is represented by the following equation: (2); represents a front suspension vertical force, represents a rear suspension vertical force, represents a distance between a metacenter and a front axle, represents a distance between a metacenter and a rear axle; a pitch moment representing the braking force generation, represented by the following equation: (3); denotes the height of the center of mass, denotes the front axle load of the whole vehicle, denotes the rear axle load of the whole vehicle; represents the pitch moment due to gravity, which is represented by the following equation: (4); denotes the sprung mass, denotes the gravitational acceleration, denotes the height difference between the center of gravity and the center of mass, denotes the vehicle body pitch angle.

18. The multi-link suspension design method of claim 17, wherein, The establishing of the braking nodding mechanical equation comprises: A front suspension actual anti-nodding angle equation and a rear suspension actual anti-nodding angle equation are respectively established.

19. The multi-link suspension design method of claim 18, wherein, The front suspension actual anti-nodding angle equation is represented by the following formula: (5); denotes the actual front-suspension anti-nodding angle, denotes the height of the center of mass, denotes the front-brake-force distribution coefficient, denotes the wheelbase; The rear suspension actual anti-nodding angle equation is represented by the following formula: (6); represents the actual rear suspension anti-nodding angle.

20. The multi-link suspension design method of claim 19, wherein, The method further comprises: actual front suspension anti-dive angle ideal front suspension anti-dive angle actual rear suspension anti-dive angle ideal rear suspension anti-dive angle ; in particular: When > and > the actual pitch center height is greater than the height of the center of mass H, and the pitch moment My during braking causes the head-up phenomenon. When = 0, the actual pitch center height is equal to the mass center height H, and the pitch deformation is zero. and = 0, the actual pitch center height is equal to the mass center height H, and the pitch deformation is zero. , the actual pitch center height is equal to the mass center height H, and the pitch deformation is zero. In other cases, an actual pitch center height is less than a center of gravity height H, ΔH is not 0, and a braking pitch moment causes nodding.

21. The multi-link suspension design method of claim 20, wherein, The establishing of the center of gravity motion equation of the multi-link suspension comprises: A virtual swing arm length equation is established; A virtual swing arm angle equation is established.

22. The multi-link suspension design method of claim 21, wherein, The virtual swing arm length equation is represented by the following formula: (7); represents a wheel center longitudinal displacement change, represents a wheel center vertical displacement change, represents a wheel center rotation angle change; The virtual swing arm degree equation is represented by the following formula: （8）。 23. The multi-link suspension design method of claim 22, wherein, The solving of the relationship between the motion displacement of the adjusting bolt and the center of gravity comprises: The adjusting bolt is arranged as a point inside the longitudinal swing arm, the length of the longitudinal swing arm is kept unchanged, and the toe camber angle is kept unchanged, and the vertical height difference between the point on the circular arc of the first arc-shaped hole and the design position hard point is obtained is a variable , the virtual swing arm angle , and the vertical height difference ; and is represented by the following formula: （9）； （10）； The height of the center of longitudinal inclination is calculated ; is represented by the following formula: (11); represents the static radius of the tire.

24. The multi-link suspension design method of claim 23, wherein, Obtaining the relationship between the displacement of the adjustable motion mechanism and the pitch and fore-aft movement of the vehicle body includes: The movement displacement of the adjusting bolt is solved in combination with formulas (9)-(11) The relationship with the longitudinal displacement x of the vehicle body is as follows: （12）； （13）； wherein the height difference between the center of mass and the trim center .

25. The multi-link suspension design method of claim 24, wherein, According to the movement displacement of the adjusting bolt, designing the structural size of the first arc-shaped hole includes: Determining that the first arc-shaped hole is a circular arc, and the circular arc radius is the length of the longitudinal swing arm; Establishing the in-plane geometric equation of the adjusting bolt as follows: （14）； wherein, L is the length of the longitudinal swing arm, D is the motion displacement of the adjustment bolt, P is the inner point of the longitudinal swing arm, Q is the outer point of the longitudinal swing arm, and Determining the up-down adjustment range of the adjusting bolt from the above in-plane geometric equation.

26. The multi-link suspension design method of claim 25, wherein, The up-down adjustment range of the adjusting bolt is-20mm-20mm, and the height adjustment range of the center of gravity is-30mm-30mm.

27. The multi-link suspension design method of claim 25, wherein, After designing the structural size of the first arc-shaped hole according to the movement displacement of the adjusting bolt, further includes: Establishing an ADAMS model containing the adjusting device, performing low-speed braking simulation, optimizing the contradiction between braking nodding and fore-aft movement, and performing performance matching for early-stage design and performance prediction for later-stage adjustment.

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