Measurement method of torsional deformation motion trajectory of vehicle leaf spring

Abstract

The present invention relates to the technical field of vehicle whole vehicle testing, and discloses a method for measuring the torsional deformation motion trajectory of a vehicle leaf spring, comprising the following steps: parking the vehicle, installing a cable displacement sensor, installing a force application device, collecting data, calculating the center point position and torsional angle of the leaf spring, and obtaining the characteristics of the measurement point trajectory changing with the braking force. The method for measuring the torsional deformation motion trajectory of a vehicle leaf spring of the present invention has a simple layout and reliable data, and realizes real-time measurement of the motion trajectory of the leaf spring on the whole vehicle, providing data support for design and development.

Description

Technical Field

[0001] The invention relates to the technical field of automobile whole vehicle testing, and in particular to a method for measuring a torsional deformation motion trajectory of a vehicle leaf spring. Background Art

[0002] In actual use, commercial vehicles often experience interference deviation during braking, steering wheel shimmy on bumpy roads, and other phenomena. In response, it is necessary to obtain the motion trajectory of the suspension system under various working conditions, so as to adjust and improve the amount of motion interference between the steering system and the suspension system.

[0003] At present, the determination of the motion interference amount of the steering system and suspension system of commercial vehicles remains only at the theoretical calculation level. The lack of bench and vehicle tests makes it impossible to fully verify the correctness of the theoretical calculation method, and it is impossible to accurately and effectively control the interference amount within a reasonable range, which affects the comfort and handling stability of the vehicle. Summary of the invention

[0004] The purpose of the present invention is to address the deficiencies of the above-mentioned technology and provide a method for measuring the torsional deformation motion trajectory of a vehicle leaf spring. The method has simple layout and reliable data, and realizes real-time measurement of the motion trajectory of the leaf spring on the whole vehicle, providing data support for design and development.

[0005] To achieve the above object, the vehicle leaf spring torsional deformation motion trajectory measurement method involved in the present invention comprises the following steps:

[0006] A) Parking: Park the front and rear wheels of the vehicle horizontally on the steps;

[0007] B) Installing the cable displacement sensor: installing three cable displacement sensors on the left and right sides of the vehicle frame, one of which is located directly above the center point of the leaf spring, and the other two are located on the sides of the leaf spring, to detect a first measuring point and a second measuring point on the leaf spring, wherein the first measuring point and the second measuring point are located above and below the center point of the leaf spring, respectively, and the first measuring point, the second measuring point and the center point of the leaf spring are located on the same straight line;

[0008] C) Installing a force applying device: a force applying position bracket is respectively arranged at the front end and the rear end of the frame, and a force applying device and a tension and pressure sensor are connected in series between the two force applying position brackets through a steel wire rope;

[0009] D) Data collection: starting the force applying device to collect data from the two tension pressure sensors and the six wire displacement sensors;

[0010] E) Calculation of the center point position and twist angle of the leaf spring: The motion trajectory of the first measurement point and the second measurement point on each leaf spring is obtained by the triangle method. The first measurement point, the second measurement point and the center point of the leaf spring are assumed to be three points on the rigid body, and e1 and e2 are assumed to be rigid body basis vectors. For vector Normalized, e2 is a unit vector perpendicular to e1, then the vector at each moment is: p1 and p2 are vectors in the rigid body basis coordinates, which remain unchanged at each moment. The vector coordinate matrix is ​​obtained under the initial conditions: Find the vector at each moment: That is, the position of the center point of the leaf spring at each moment in the test frame coordinate system is obtained, and the vector at each moment is taken The vector angle change in the frame coordinate system is defined as the leaf spring twist angle;

[0011] F) Obtaining the characteristics of the measurement point trajectory changing with the braking force: subtracting the initial position from the center point position trajectory of the leaf spring obtained in step E) to obtain the characteristics of the measurement point trajectory changing with the braking force.

[0012] Preferably, in the step C), the point where the force application position bracket bears the longitudinal force is at the same height as the tire ground contact point in a fully loaded state.

[0013] Preferably, in the step D), when the force applying device is started, the left and right force applying devices are operated synchronously to apply a longitudinal braking force corresponding to a braking deceleration from 0N to 0.8g.

[0014] Preferably, in step D), the Z0 position is selected as the ground, and the X0 position is selected as the middle position of the axle.

[0015] Preferably, in the step F), the characteristics of the measurement point trajectory changing with the braking force include torsional stiffness characteristics and deformation trajectory characteristics.

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] 1. Indirectly obtain the trajectory of the leaf spring moving with the suspension system, with accurate measurement, and the movement trajectory can be obtained from any point that remains stable with the leaf spring;

[0018] 2. After fitting the motion trajectory of the center point of the leaf spring, corresponding adjustments can be made based on the motion trajectory, which is of great significance to improving driving comfort and handling stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the installation of the wire displacement sensor in the method for measuring the torsional deformation motion trajectory of a vehicle leaf spring of the present invention;

[0020] Figure 2 It is a schematic diagram of the installation of the force applying device in the present invention;

[0021] Figure 3 It is a schematic diagram of the torsional stiffness characteristics of a leaf spring;

[0022] Figure 4 It is a schematic diagram of the twisting deformation trajectory characteristics of the leaf spring;

[0023] Figure 5 Schematic diagram of the intersection of arcs in the triangulation method.

[0024] The components in the figure are numbered as follows:

[0025] Vehicle frame 1, wire displacement sensor 2, force application position bracket 3, steel wire rope 4, force application device 5. DETAILED DESCRIPTION

[0026] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] The present invention provides a method for measuring the torsional deformation motion trajectory of a vehicle leaf spring, comprising the following steps:

[0028] A) Parking: Park the front and rear wheels of the vehicle horizontally on the steps;

[0029] B) Install the wire displacement sensor: Figure 1 As shown, three cable displacement sensors 2 are respectively installed at the left and right side frames 1 of the vehicle, one of which is located directly above the center point P of the leaf spring, and the other two are located on the sides of the leaf spring to detect a first measuring point B1 and a second measuring point B2 on the leaf spring, the first measuring point B1 and the second measuring point B2 are respectively located above and below the center point P of the leaf spring, and the first measuring point B1, the second measuring point B2 and the center point P of the leaf spring are located on the same straight line;

[0030] C) Install the force-applying device: Figure 2 As shown, force application position brackets 3 are respectively arranged at the front end and the rear end of the frame 1, and a force application device 5 and a tension pressure sensor 6 are connected in series between the two force application position brackets 3 through a steel wire rope 4, and the point where the force application position bracket 3 bears the longitudinal force is at the same height as the tire ground contact point in a fully loaded state;

[0031] D) Data collection: Start the force applying device 5, and the left and right force applying devices 5 are operated synchronously, and the longitudinal braking force corresponding to the braking deceleration from 0N to 0.8g is applied, and the data of the two tension pressure sensors 6 and the six cable displacement sensors 2 are collected, and the Z0 position is selected as the ground, and the X0 position is selected as the middle position of the axle;

[0032] E) Calculation of leaf spring center point position and twist angle: The motion trajectory of the first measurement point B1 and the second measurement point B2 on each leaf spring is obtained by the triangle method. The first measurement point B1, the second measurement point B2 and the leaf spring center point P are assumed to be three points on the rigid body, and e1 and e2 are assumed to be rigid body basis vectors. For vector Normalized, e2 is a unit vector perpendicular to e1, then the vector at each moment is: p1 and p2 are vectors in the rigid body basis coordinates, which remain unchanged at each moment. The vector coordinate matrix is ​​obtained under the initial conditions: Find the vector at each moment: That is, the position of the center point P of the leaf spring at each time in the test frame coordinate system is obtained, and the vector at each time is taken The vector angle change in the frame coordinate system is defined as the leaf spring twist angle;

[0033] F) Obtain the characteristics of the measurement point trajectory changing with the braking force: Figure 3 and Figure 4 As shown, the position trajectory of the leaf spring center point P obtained in step E) is subtracted from the initial position to obtain the characteristics of the measurement point trajectory changing with the braking force. The characteristics of the measurement point trajectory changing with the braking force include torsional stiffness characteristics and deformation trajectory characteristics.

[0034] In this embodiment, the principle of the triangle method is as follows Figure 5 As shown, the horizontal and vertical wire displacement sensors 2 record the distance between the measuring point B and the sensor installation point (point A and point C) (the distance values ​​are r1 and r2). The position of the measuring point at different times is the intersection of the arcs with point A and point C as the center and r1 and r2 as the radius. The position points can be calculated by drawing method to obtain the trajectory of the measuring points.

[0035] The above method cleverly uses the triangle method to measure the motion trajectory of two points in the same plane, thereby obtaining the trajectory of the leaf spring moving with the suspension system. Although the triangle method can only obtain the position of points in the plane, for the front suspension movement, the main movement of the parts under the bouncing and braking conditions is in the plane parallel to the frame. Therefore, ignoring the movement in the Y direction greatly simplifies the measurement and calculation methods, and the impact on the measurement accuracy can be ignored.

[0036] The method for measuring the motion trajectory of the torsion deformation of a vehicle leaf spring of the present invention indirectly obtains the trajectory of the leaf spring moving with the suspension system, and the measurement is accurate. The motion trajectory can be obtained from any point that remains stable and unchanged with the leaf spring, wherein the most meaningful point is the front axle knuckle point. The motion trajectory of this point is directly related to the motion interference amount of the steering system and the suspension system. Whether the motion trajectory of this point is appropriate and the degree of overlap between the motion trajectory of the steering rod and the motion trajectory of this point directly affect the performance of the vehicle. If the interference amount is too large, it will cause problems such as unintentional rotation of the steering wheel during vertical jumping and deviation during braking. After the motion trajectory of the center point of the leaf spring is fitted, corresponding adjustments can be made according to the motion trajectory, which is of great significance to improving driving comfort and handling stability.

Claims

1. A method for measuring the torsional deformation motion trajectory of a vehicle leaf spring, characterized in that: The steps include: A) Parking: Park the front and rear wheels of the vehicle horizontally on the steps; B) Installing the cable displacement sensor: installing three cable displacement sensors (2) on the left and right side frames (1) of the vehicle, respectively, wherein one of the cable displacement sensors (2) is located directly above the center point P of the leaf spring, and the other two are located on the sides of the leaf spring, to detect a first measuring point B1 and a second measuring point B2 on the leaf spring, wherein the first measuring point B1 and the second measuring point B2 are located above and below the center point P of the leaf spring, respectively, and the first measuring point B1, the second measuring point B2 and the center point P of the leaf spring are located on the same straight line; C) installing a force applying device: a force applying position bracket (3) is respectively arranged at the front end and the rear end of the vehicle frame (1), and a force applying device (5) and a tension pressure sensor (6) are connected in series between the two force applying position brackets (3) via a steel wire rope (4); D) Data collection: starting the force applying device (5) to collect data from the two tension pressure sensors (6) and the six tension wire displacement sensors (2); E) Calculation of the center point position and twist angle of the leaf spring: The motion trajectory of the first measurement point B1 and the second measurement point B2 on each leaf spring is obtained by the triangle method. The first measurement point B1, the second measurement point B2 and the center point P of the leaf spring are assumed to be three points on the rigid body, and e1 and e2 are assumed to be rigid body basis vectors. For vector Normalized, e2 is a unit vector perpendicular to e1, then the vector at each moment is: p1 and p2 are vectors in the rigid body basis coordinates, which remain unchanged at each moment. The vector coordinate matrix is ​​obtained under the initial conditions: Find the vector at each moment: That is, the position of the center point P of the leaf spring at each time in the test frame coordinate system is obtained, and the vector at each time is taken The vector angle change in the frame coordinate system is defined as the leaf spring twist angle; F) Obtaining the characteristics of the measurement point trajectory changing with the braking force: subtracting the initial position from the position trajectory of the center point P of the leaf spring obtained in step E) to obtain the characteristics of the measurement point trajectory changing with the braking force.

2. The method for measuring the torsional deformation motion trajectory of a vehicle leaf spring according to claim 1, characterized in that: In the step C), the point where the force application position bracket (3) bears the longitudinal force is at the same height as the tire ground contact point in the fully loaded state.

3. The method for measuring the torsional deformation motion trajectory of a vehicle leaf spring according to claim 1, characterized in that: In the step D), when the force applying device (5) is started, the left and right force applying devices (5) are operated synchronously to apply a longitudinal braking force corresponding to a braking deceleration from 0N to 0.8g.

4. The method for measuring the torsional deformation motion trajectory of a vehicle leaf spring according to claim 1, characterized in that: In the step D), the Z0 position is selected as the ground, and the X0 position is selected as the middle position of the axle.

5. The method for measuring the torsional deformation motion trajectory of a vehicle leaf spring according to claim 1, characterized in that: In the step F), the characteristics of the measurement point trajectory changing with the braking force include torsional stiffness characteristics and deformation trajectory characteristics.

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