CN114936492A

CN114936492A - Method for improving checking precision of motion clearance of passenger vehicle suspension

Info

Publication number: CN114936492A
Application number: CN202210552631.9A
Authority: CN
Inventors: 李继川; 韩超; 王涛; 邓石超; 王旭; 赵星明; 许晓珊
Original assignee: FAW Group Corp
Current assignee: FAW Group Corp
Priority date: 2022-05-19
Filing date: 2022-05-19
Publication date: 2022-08-23

Abstract

The invention discloses a method for improving the checking precision of the suspension motion clearance of a passenger vehicle, which comprises the steps of dividing a three-dimensional model mesh of each part; after the material attribute and the unit attribute are given, outputting a grid model file; establishing the connection relation of all parts, wherein the auxiliary frame and the control arm are connected with the vehicle body through a bushing, and the auxiliary frame is connected with the steering knuckle through a bushing; simulating the bushings by using a Connector unit, obtaining a translational rigidity curve of each bushing, and assigning the translational rigidity curve to the corresponding Connector unit; applying load working condition setting of a suspension under a whole vehicle coordinate system, and completing construction of a system model; outputting a deformed grid of the odb file result of all parts of the suspension system under the working conditions of the jump-up limit and the jump-down limit in Abaqus software, and importing the deformed grid into hypermesh software; the method aims to solve the problem of checking the movement clearance of the suspension system of the passenger car, and compared with the traditional suspension system movement clearance checking method, the method can improve the precision of checking the movement clearance.

Description

Method for improving checking precision of motion clearance of passenger vehicle suspension

Technical Field

The invention relates to the technical field of vehicle design, in particular to a method for improving checking precision of a suspension motion gap of a passenger vehicle.

Background

When a vehicle runs on a road, different road conditions can be met. The suspension system can generate a motion form of jumping up and jumping down along with the change of road conditions. During the up-jump and down-jump movements, relative motion is generated between the parts of the suspension system. If the initial clearance between the components is not properly designed, motion interference will occur. The motion interference can cause abnormal sound of the vehicle, and interference indentation can occur among parts due to serious interference; the indentation is a source of fatigue cracks, and fatigue failure can occur after a long time, so that serious potential safety hazards exist. Therefore, checking the movement gap of the suspension system is particularly important in the early stage of vehicle development; and the accuracy of the movement clearance check reflects the design level of the suspension.

The general process of checking the motion clearance of the suspension system is as follows: and checking the gaps of all parts under the postures of the upper jump limit and the lower jump limit in the designed posture of the suspension, and if all parts under the two postures of the limit are not interfered, the problem of motion interference cannot occur in the motion process.

At present, two methods for checking the motion clearance of a suspension system are mainly used, one is Dmu motion simulation based on Catia software, and the other is dynamic motion simulation based on Adams software. The two methods can realize the checking of the movement clearance of the suspension system, but the precision is poor, and all the movement interference problems cannot be identified.

Dmu method can take into account kinematic pairs in the suspension system, but cannot take into account the effect of the stiffness of the rubber bushing and the elastic deformation of the components during suspension motion. Adams dynamic motion simulation can consider the influence of the rigidity of a kinematic pair and a bush on the motion of a suspension system, and because parts of the Adams dynamic motion simulation are all rigid bodies, the elastic deformation of the parts is not considered; and the elastic deformation of the parts often influences the stress of the system, and sometimes even subverts the simulation result.

Disclosure of Invention

The invention aims to provide a method for improving the checking precision of the motion clearance of a passenger vehicle suspension, so as to solve the problems in the background technology.

In order to achieve the purpose, the invention provides the following technical scheme: a method for improving the checking precision of the motion clearance of a passenger vehicle suspension comprises the following components of an auxiliary frame, a steering knuckle, a spring, an upper spring cushion, a lower spring cushion, a shock absorber, a stabilizer bar, an upper control arm, a lower control arm, a toe-in arm, a longitudinal arm buffer block and a wheel center, and comprises the following steps:

establishing a three-dimensional model of each component of the suspension;

carrying out mesh division on the three-dimensional model of each part in Hypermesh software;

respectively endowing the divided grids with material attributes and unit attributes, and outputting a grid model file generated by Hypermesh software;

importing the grid model file into Hypermesh software, and establishing connection relations among all components, wherein an auxiliary frame, an upper control arm, a lower control arm, a toe-in arm and a longitudinal arm are connected with a vehicle body through bushings, and the auxiliary frame is connected with a steering knuckle through the bushings;

simulating a Connector unit established by Hypermesh software, wherein two nodes of the Connector unit are respectively and rigidly connected with other components, establishing a local Cartesian coordinate system of the bushing at all positions of the bushing, and establishing a relation between the Connector unit and the local coordinate system;

obtaining a translational stiffness curve of each bushing, and assigning the stiffness curve of each bushing to a corresponding connector unit respectively;

applying load working condition setting of a suspension under a whole vehicle coordinate system, wherein the load working conditions are a preloading working condition, an up-jump limit working condition and a down-jump limit working condition respectively;

outputting the displacement of all the nodes and completing the construction of a system model;

outputting the system model as an inp file, submitting the inp file to abaqus software for calculation, and outputting a calculation result of the odb file;

and outputting the deformed grids of the odb file results of all parts of the suspension system under the working conditions of the jump-up limit and the jump-down limit in the Abaqus software, and importing the deformed grids into hypermesh software.

Further, the grid unit comprises a solid grid unit and a plate shell grid unit, wherein the auxiliary frame, the steering knuckle, the upper control arm, the upper cushion, the lower cushion and the spring are divided into the solid grid unit, and the lower control arm, the longitudinal arm and the toe-in arm are divided into the plate shell grid unit.

Further, the spring is divided into hexahedral units.

Further, the rigidity of the spring is determined by meshing the three-dimensional model of the spring; and obtaining the axial rigidity of the buffer block through a test curve.

Further, a liner translational stiffness curve is obtained by formula 1, and the stiffness curve is assigned to the connector unit, wherein formula 1 is:

wherein x is the compression of the liner thickness, k is the liner linear stiffness, T is the liner thickness, α is the correction factor, α > 0 and is a real number.

Furthermore, a three-dimensional model established by the auxiliary frame, the steering knuckle, the upper spring cushion, the lower spring cushion, the shock absorber, the stabilizer bar, the upper control arm, the lower control arm and the toe-in arm, the trailing arm and the buffer block is a three-dimensional model of a designed posture, and the three-dimensional model of the spring is a three-dimensional model of a free posture.

Furthermore, a lower spring cushion is rigidly connected with the control arm, an upper spring cushion is rigidly connected with the vehicle body, and the spring is respectively abutted against the upper spring cushion and the lower spring cushion; the buffer block is simulated by a SpringA unit, one end of the unit is rigidly connected to the control arm, and the other end of the unit is rigidly connected to the vehicle body; the wheel center point is rigidly connected with the auxiliary frame bearing; the vehicle body is not included in the system model, and each point on the vehicle body is defined as a constraint point.

Further, the load condition applied under the whole vehicle coordinate system is set to be the constraint setting and the loading setting.

Further, still include: the constraint of the preloading working condition is set as 6 directional degrees of freedom of respective connection points of the auxiliary frame, the control arm and the buffer block and the vehicle body, and 3 directional degrees of freedom of a wheel center point, and the loading of the preloading working condition is set as that the upper cushion of the spring is compressed to a designed attitude position; the constraint of the up-jump limit working condition is set as 6 directional degrees of freedom of respective connection points of the auxiliary frame, the control arm and the buffer block and the vehicle body, at the moment, the upper cushion of the spring is kept at a designed attitude position, and the load of the up-jump limit working condition is set as a preload working condition, and the wheel center is forced to move upwards to the up-jump limit position; the restraint of the limited working condition of the kick-down is set as 6 direction degrees of freedom of respective connection points of the auxiliary frame, the control arm and the buffer block with the vehicle body, the upper soft cushion of the spring is kept at the position of the designed posture at the moment, the loading of the limited working condition of the kick-down is set as the preloading working condition, and the wheel center applies forced displacement downwards to the limited position of the kick-down.

Furthermore, the plate shell unit directly generates geometry, and the entity unit generates a face surface and then generates the face surface into geometry; and outputting all the geometries as igs files, and finally importing the igs files into cata software for checking the result of gap checking.

Compared with the prior art, the invention has the beneficial effects that: the method aims to solve the problem of checking the movement clearance of the suspension system of the passenger car, and compared with the traditional suspension system movement clearance checking method, the method can improve the precision of checking the movement clearance.

Drawings

FIG. 1 is a flowchart of a method for improving the checking accuracy of the suspension motion gap of a passenger vehicle according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of an E-type multi-link suspension configuration in accordance with an embodiment of the present invention;

FIG. 3 is a graph of the stiffness of the Y-direction bushing of the lower control arm in an embodiment of the present invention;

FIG. 4 is a schematic diagram of gap checking according to an embodiment of the present invention;

FIG. 5 is a liner stiffness curve processing equation in an embodiment of the present invention;

in the figure: 1. a soft cushion is arranged on the spring; 2. a spring; 3. an auxiliary frame; 4. a buffer block; 5. a lower control arm; 6. a soft cushion under the spring; 7. a toe-in arm; 8. a knuckle; 9. a trailing arm; 10. an upper control arm.

Detailed Description

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

In the description of the present invention, "a plurality" means two or more unless otherwise specified; the terms "upper", "lower", "left", "right", "inner", "outer", "front", "rear", "head", "tail", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are merely for convenience in describing the present invention and to simplify the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed in a particular orientation, and be operated, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," "third," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the present invention, it is to be noted that, unless otherwise explicitly specified or limited, the terms "connected" and "connected" are to be interpreted broadly, e.g., as being fixed or detachable or integrally connected; can be mechanically or electrically connected; may be directly connected or indirectly connected through an intermediate. The specific meanings of the above terms in the present invention can be understood in a specific case to those of ordinary skill in the art.

In view of the above problems, it is an object of the present invention to provide a method for improving the accuracy of checking the backlash of a suspension. The method mainly comprises the steps of building a suspension system finite element model, considering rigidity curves of a lining and a buffer block, calculating the suspension system finite element model by utilizing Abaqus software to obtain suspension system postures under different working conditions, and checking gaps of parts of the suspension system under different postures.

Referring to the attached drawings of the specification, the invention provides a technical scheme that: a method for improving the checking precision of the motion clearance of a passenger vehicle suspension is disclosed, as shown in figure 2, the suspension components comprise a sub-frame 3, a steering knuckle 8, a spring 2, an upper spring soft pad 1, a lower spring soft pad 6, a shock absorber, a stabilizer bar, an upper control arm 10, a lower control arm 5, a toe-in arm 7, a trailing arm 9, a buffer block 4 and a wheel center, as shown in figure 1, the method comprises the following steps:

s100, establishing a three-dimensional model of each part of the suspension;

s200, carrying out mesh division on the three-dimensional model of each part in Hypermesh software;

s300, respectively endowing the divided grids with material attributes and unit attributes, and outputting a grid model file generated by Hypermesh software;

s400, importing the grid model file into Hypermesh software, and establishing connection relations among all parts, wherein as shown in FIG. 2, an auxiliary frame 3, an upper control arm 10, a lower control arm 5, a toe-in arm 7 and a longitudinal arm 9 are connected with a vehicle body through bushings, and the auxiliary frame 3 is connected with a steering knuckle 8 through bushings;

the bushing is simulated by a Connector unit established by Hypermesh software, two nodes of the unit are respectively and rigidly connected with other components, a local Cartesian coordinate system of the bushing is established at all positions of the bushing, and the relationship between the Connector unit and the local coordinate system is established;

s500, applying load working condition setting of the suspension under a whole vehicle coordinate system, wherein the load working conditions are a preloading working condition, an up-jump limit working condition and a down-jump limit working condition respectively;

s600, outputting the displacement of all the nodes and completing the construction of a system model;

s700, outputting the system model as an inp file, submitting the inp file to abaqus software for calculation, and outputting a calculation result of the odb file;

and S800, outputting the deformed grids of the odb file results under the working conditions of the upper jump limit and the lower jump limit of all parts of the suspension system in the Abaqus software, and importing the deformed grids into hypermesh software.

In the above embodiment, preferably, the suspension is an E-type multi-link suspension.

Optionally, the grid cells include solid grid cells and shell grid cells, wherein the subframe 3, the knuckle 8, the upper control arm 10, the sprung cushion 1, and the spring 2 are divided into the solid grid cells, and the lower control arm 5, the trailing arm 9, and the toe-in arm 7 are divided into the shell grid cells.

Alternatively, the spring 2 is divided into hexahedral units.

In the above embodiment, since the calculation is quasi-static, the damper is not operated, and the influence of the damper is ignored.

Optionally, the stiffness of the spring 2 is determined by meshing the three-dimensional model of the spring 2; and obtaining the axial rigidity of the buffer block through a test curve.

Optionally, a liner translational stiffness curve is obtained by equation 1, and the stiffness curve is assigned to a connector unit, where equation 1 is:

wherein x is the compression amount of the thickness of the lining, k is the linear rigidity of the lining, T is the thickness of the lining, alpha is a correction coefficient, alpha is more than 0 and is a real number.

In the embodiment, the system comprises three elastic elements, namely a lining, a buffer block and a spring, wherein the rigidity of the spring structure is determined after grid drawing is finished; the buffer block has a simple structure, and can be obtained through a test curve only by considering the axial rigidity, so that the axial rigidity curve of the buffer block can be determined. On the premise of knowing the linear stiffness of each bushing in each direction and the thickness of each direction, a translational stiffness curve of each bushing is obtained by using a formula 1 and adjusting a correction coefficient alpha, fig. 3 is a stiffness curve of the bushing of the lower control arm, and the stiffness curve of each bushing is assigned to a corresponding connector unit respectively.

The bush is generally rubber material, and according to the functional requirement, all has the design requirement to all direction rigidity, and the structure is more complicated. The test of the stiffness curve of the rubber bushing is also complex, and the test stiffness curve under the general condition is only limited to a linear section; even if some non-linear sections exist, the test curve is not smooth and the rigidity suddenly becomes small due to the return phenomenon because the test curve is limited by the capability of equipment. However, in two limit working conditions in the motion interference check of the suspension system, most of the rubber bushings enter a nonlinear interval, so that most of the rigidity curves of the bushings cannot meet the abaqus calculation requirement at present, and the nonlinear section of the curve needs to be processed on the basis of the original bushing curve, so that the curve is smooth and prolonged; but is limited by the treatment level, and the curve difference after treatment is large.

In order to simplify the processing process of the liner curve and unify the processing standard, a liner curve processing method is provided below.

The liner is provided with rigidity in six directions, including three translational rigidities and three rotational rigidities under a liner local coordinate system, and the rigidity in the three rotational directions is in a linear interval in the motion process of the suspension system, so that only the rigidity curves in the three translational directions need to be processed.

As shown in FIG. 3, if the thickness of the lining is Tmm, the translation stiffness curve of the lining is a linear section in the interval of (0-T/3), and is a nonlinear section in the interval of (T/3-2T/3). The stiffness curve needs to ensure that the first derivative at T/3 is liner linear stiffness k and continuous, and the first derivative at 2T/3 tends to be infinite. The processing formula of the rigidity curve of the bushing is shown as formula 1, and the rigidity curve is a piecewise function.

The larger the alpha value is, the faster the speed of the nonlinear section approaching infinity is, and according to partial measurement data of the nonlinear section of the liner stiffness curve, a smooth curve close to a real curve can be fitted by adjusting the alpha value.

According to the method, the rigidity curves of the local coordinate system of the bushing in three translation directions are processed, and each bushing can obtain three smooth translation rigidity curves; and the linear rigidity of the rotation in three directions is added, six-direction rigidity setting of each bushing in a bushing local coordinate system is completed, and the rigidity setting can be assigned to a connector unit of each bushing.

Alternatively, as shown in fig. 2, the three-dimensional models established by the subframe 3, the knuckle 8, the upper spring cushion 1, the lower spring cushion 6, the shock absorber, the stabilizer bar, the upper control arm 10, the lower control arm 5, the toe arm 7, the trailing arm 9, and the cushion block 4 are three-dimensional models of design postures, and the three-dimensional model of the spring 2 is a three-dimensional model of free postures.

Optionally, the lower spring cushion 6 is rigidly connected with the control arm, the upper spring cushion 1 is rigidly connected with the vehicle body, and the spring 2 is respectively abutted against the upper spring cushion 1 and the lower spring cushion 6; the buffer block 4 is simulated by a SpringA unit, one end of the unit is rigidly connected to the control arm, and the other end of the unit is rigidly connected to the vehicle body; the wheel center point is rigidly connected with a bearing of the auxiliary frame 3; the vehicle body is not included in the system model, and each point on the vehicle body is defined as a constraint point.

Optionally, the load condition applied under the whole vehicle coordinate system is set to be the constraint setting and the loading setting.

Optionally, the method further comprises: the constraint of the preloading working condition is set as six directional degrees of freedom of respective connection points of the auxiliary frame 3, the control arm and the buffer block 4 and the vehicle body, three directional degrees of freedom of a wheel center point, and the loading of the preloading working condition is set as that the upper cushion 1 of the spring is compressed to a designed posture position, wherein the designed posture position is preferably 65mm in the Z negative direction;

the constraint of the up-jump limit working condition is set as six directional degrees of freedom of the connection points of the auxiliary frame 3, the control arm and the buffer block 4 with the vehicle body respectively, at the moment, the upper cushion 1 of the spring is kept at the position of the designed posture, the loading of the up-jump limit working condition is set as the preloading working condition, the wheel center is forced to move upwards to the up-jump limit position, wherein the forced displacement is preferably 95mm in the Z positive direction;

the constraint of the limited down-jump working condition is set as six degrees of freedom of respective connection points of the auxiliary frame 3, the control arm and the buffer block 4 and the vehicle body, at the moment, the upper spring cushion 1 is kept at a designed posture position, the loading of the limited down-jump working condition is set as a preloading working condition, the wheel center applies forced displacement downwards to the limited down-jump position, and the preferred forced displacement is Z negative 105 mm.

Optionally, the shell unit directly generates geometry, and the entity unit generates a face surface and then generates the face surface into geometry; and outputting all the geometries into an igs file, and finally importing the igs file into cata software for checking the result of gap checking.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims

1. The utility model provides a method for improve passenger car suspension motion clearance check precision, the part of constituteing the suspension includes sub vehicle frame, knuckle, spring, the cushion on the spring, cushion under the spring, bumper shock absorber, stabilizer bar, control arm, buffer block and wheel center, wherein, the control arm includes control arm, lower control arm, toe-in arm, the trailing arm, its characterized in that includes:

establishing a three-dimensional model of each component of the suspension;

2. The method of claim 1, wherein the grid cells comprise solid grid cells and plate shell grid cells, wherein the sub-frame, the knuckle, the upper control arm, the upper cushion, the lower cushion and the spring are divided into solid grid cells, and the lower control arm, the trailing arm and the toe arm are divided into plate shell grid cells.

3. The method for improving the accuracy of checking the running clearance of the suspension of a passenger car as claimed in claim 2, wherein the spring is divided into hexahedral units.

4. The method for improving the checking accuracy of the motion clearance of the suspension of the passenger car according to the claim 1, characterized in that the rigidity of the spring is determined by meshing the three-dimensional model of the spring; and obtaining the axial rigidity of the buffer block through a test curve.

5. The method for improving the motion gap checking accuracy of the passenger vehicle suspension fork according to the claim 1, characterized in that a bushing translation stiffness curve is obtained by the following formula 1, and the stiffness curve is assigned to a connector unit, wherein the formula 1 is as follows:

6. The method for improving the checking accuracy of the motion gap of the suspension of the passenger vehicle as claimed in claim 1, wherein the three-dimensional model built by the auxiliary frame, the steering knuckle, the upper spring cushion, the lower spring cushion, the shock absorber, the stabilizer bar, the upper control arm, the lower control arm, the toe-in arm, the trailing arm and the buffer block is a three-dimensional model of a design posture, and the three-dimensional model of the spring is a three-dimensional model of a free posture.

7. The method for improving the checking accuracy of the motion clearance of the suspension of the passenger car as claimed in claim 1, wherein the lower cushion of the spring is rigidly connected with the control arm, the upper cushion of the spring is rigidly connected with the car body, and the spring is respectively abutted against the upper cushion of the spring and the lower cushion of the spring; the buffer block is simulated by a SpringA unit, one end of the unit is rigidly connected to the control arm, and the other end of the unit is rigidly connected to the vehicle body; the wheel center point of the wheel center is rigidly connected with the auxiliary frame bearing; the vehicle body is not included in the system model, and each point on the vehicle body is defined as a constraint point.

8. The method for improving the checking accuracy of the suspension motion gap of the passenger vehicle according to claim 1, wherein the load condition applied under the whole vehicle coordinate system is set to be a constraint setting and a loading setting.

9. The method for improving the checking precision of the motion clearance of the suspension of the passenger car according to claim 8, is characterized by comprising the following steps:

the constraint of the preloading working condition is set as six directional degrees of freedom of connection points of the auxiliary frame, the control arm and the buffer block with the vehicle body respectively, three directional degrees of freedom of a wheel center point are set, and the loading of the preloading working condition is set as that the cushion on the spring is compressed to a designed attitude position;

the constraint of the up-jump limit working condition is set as six directional degrees of freedom of respective connection points of the auxiliary frame, the control arm and the buffer block with the vehicle body, at the moment, the upper cushion of the spring is kept at a designed attitude position, and the loading of the up-jump limit working condition is set as a preloading working condition, and the wheel center is forced to move upwards to the up-jump limit position;

the constraint of the limited down-jump working condition is set as six directional degrees of freedom of respective connection points of the auxiliary frame, the control arm and the buffer block and the vehicle body, the upper cushion of the spring is kept at a designed attitude position at the moment, and the wheel center is forced to move to the limited down-jump position by applying force under the loading of the limited down-jump working condition set as the preloading working condition.

10. The method for improving the checking precision of the motion clearance of the suspension of the passenger vehicle as claimed in claim 1, wherein the plate shell unit directly generates geometry, and the surface is generated into geometry after the entity unit generates the surface; and outputting all the geometries as igs files, and finally importing the igs files into cata software for checking the result of gap checking.