阅读说明：本技术 一种商用车盘式制动器总成btv的测量及数据处理方法 (Method for measuring and processing data of BTV (brake torque converter) of commercial vehicle disc brake assembly ) 是由 王应国 曾繁卓 张志� 雷文 李伟 任学良 于 2021-10-12 设计创作，主要内容包括：本发明提出了一种商用车盘式制动器总成BTV的测量及数据处理方法,该测量系统包括制动器惯性试验台,还包括用于测量制动器产生的制动力的力传感器、用于测量制动盘速度的速度传感器、用于测量制动盘加速度的加速度传感器、用于向制动管路加压的加压器、用于测量制动盘温度的温度传感器、控制器和计时器；控制器根据力传感器、速度传感器、加速度传感器、加压器、温度传感器和计时器之一或者任意组合测得的数据,获取BTV值。本发明能够对BTV值进行测量。(The invention provides a method for measuring and processing data of a commercial vehicle disc brake assembly BTV, wherein a measuring system comprises a brake inertia test bed, a force sensor for measuring braking force generated by a brake, a speed sensor for measuring the speed of a brake disc, an acceleration sensor for measuring the acceleration of the brake disc, a pressurizer for pressurizing a brake pipeline, a temperature sensor for measuring the temperature of the brake disc, a controller and a timer; the controller acquires the BTV value according to data measured by one or any combination of a force sensor, a speed sensor, an acceleration sensor, a pressurizer, a temperature sensor and a timer. The invention can measure the BTV value.)

1. A measuring system of a commercial vehicle disc brake assembly BTV comprises a brake inertia test bed and is characterized by further comprising a force sensor for measuring braking force generated by a brake, a speed sensor for measuring speed of a brake disc, an acceleration sensor for measuring acceleration of the brake disc, a pressurizer for pressurizing a brake pipeline, a temperature sensor for measuring temperature of the brake disc, a controller and a timer;

the force data output end of the force sensor is connected with the force data input end of the controller, the speed data output end of the speed sensor is connected with the speed data output end of the controller, the speed data output end of the acceleration sensor is connected with the acceleration data output end of the controller, the temperature data output end of the temperature sensor is connected with the temperature data input end of the controller, the pressurization/decompression data output end of the controller is connected with the pressurization/decompression data input end of the pressurizer, the pressure data output end of the pressurizer is connected with the pressure data input end of the controller, the starting timing data output end of the controller is connected with the starting timing data input end of the timer, the stopping timing data output end of the controller is connected with the stopping timing data input end of the timer, and the timing data output end of the timer is connected with the timing data input end of the controller;

the controller acquires the BTV value according to data measured by one or any combination of a force sensor, a speed sensor, an acceleration sensor, a pressurizer, a temperature sensor and a timer.

2. The measuring system for a commercial vehicle disc brake assembly BTV according to claim 1, characterized by further comprising a support frame, wherein a mounting plate is arranged on the support frame, a speed sensor fixing mounting seat for fixedly mounting a speed sensor is arranged on the mounting plate, an acceleration sensor fixing mounting seat for fixedly mounting an acceleration sensor is arranged on the mounting plate, and a temperature sensor fixing mounting seat for fixedly mounting a temperature sensor is arranged on the mounting plate;

the speed sensor is fixedly installed on the speed sensor fixed installation seat, the acceleration sensor is fixedly installed on the acceleration sensor fixed installation seat, and the temperature sensor is fixedly installed on the temperature sensor fixed installation seat.

3. A data processing method of a commercial vehicle disc brake assembly BTV is characterized by comprising the following steps:

s1, the controller judges whether the rotating speed of the brake disc reaches a preset initial speed threshold value:

if the rotating speed of the brake disc reaches the preset initial speed threshold, the brake disc keeps rotating at the preset initial speed threshold, and step S2 is executed;

if the rotating speed of the brake disc is higher than the preset initial speed threshold, the controller sends a control signal to the brake inertia test bed of the brake inertia test bed, controls the rotating speed of the brake disc to be reduced, enables the rotating speed of the brake disc to be equal to the preset initial speed threshold, and returns to the step S1;

if the rotating speed of the brake disc is lower than the preset initial speed threshold, the controller sends a control signal to the brake inertia test bed of the brake inertia test bed, controls the rotating speed of the brake disc to be increased, enables the rotating speed of the brake disc to be equal to the preset initial speed threshold, and returns to the step S1;

s2, the controller sends a control signal to the pressurizer, and the pressurizer pressurizes the brake pipeline to enable the acceleration detected by the acceleration sensor to be a preset acceleration threshold value;

when the pressure value input by the pressurizer to the brake pipeline is equal to a preset pressure threshold value and the duration time is greater than or equal to a preset time threshold value, the controller sends a timing starting control signal to the timer of the pressurizer, and the timer records that the time is t 1;

when the controller receives that the speed detected by the speed sensor is smaller than or equal to a preset speed threshold value, the preset speed threshold value is smaller than a preset initial speed threshold value, the controller sends a timing stopping control signal to a timer of the controller, and the timer records that the time is t 2;

s3, obtaining the braking force generated by the brake and detected by the force sensor at the time period of t 1-t 2, fitting the braking force according to the time period of t 1-t 2 to obtain a braking force fitting curve, and obtaining a braking torque curve through the braking force fitting curve;

and S4, obtaining the BTV value according to the brake torque curve.

4. A data processing method of a commercial vehicle disc brake assembly BTV according to claim 3, wherein in step S4, the BTV value calculating method comprises the steps of:

s41, numbering all wave crests and wave troughs on the braking torque curve in sequence, wherein the wave crests and the wave troughs are respectively X₁、X₂、X₃、……、X_x，Y₁、Y₂、Y₃、……、Y_yWherein X represents the total number of peaks, y represents the total number of valleys, and X₁Denotes the 1 st peak, X₂Denotes the 2 nd peak, X₃Denotes the 3 rd peak, X_xDenotes the x peak, Y₁Denotes the 1 st trough, Y₂Denotes the 2 nd trough, Y₃Denotes the 3 rd trough, Y_yRepresents the y trough;

s42, acquiring adjacent peak-valley difference values of adjacent peaks and valleys;

and S43, obtaining a BTV value according to the difference value of adjacent peaks and valleys.

5. A data processing method of a commercial vehicle disc brake assembly BTV according to claim 3, wherein in step S42, the calculation method of the adjacent peak-to-valley difference value is:

wherein, | | represents taking an absolute value;

e_Xvrepresenting a braking torque value corresponding to the v peak; v ∈ {1,2,3,..., x };

V_v,δrepresenting adjacent peak-to-valley difference values;

or/and in step S43, the BTV value is calculated by the following method:

wherein, V_v,δRepresenting a phaseA difference between adjacent peaks and valleys;

x represents the total number of peaks;

y represents the total number of troughs;

V_avgthe BTV value is shown.

6. A data processing method of a commercial vehicle disc brake assembly BTV according to claim 3, characterized in that in step S3, the calculation method of the braking torque curve is:

wherein the content of the first and second substances,representing a braking force fitting curve;

f represents the moment arm value;

the braking torque curve is shown.

7. A data processing method for a commercial vehicle disc brake assembly BTV according to claim 3, wherein in step S3, the method for obtaining a braking force fitting curve through braking force fitting comprises the following steps:

s31, carrying out fast Fourier transform on the braking force in the time period from t1 to t2 to obtain a braking force frequency domain signal;

s32, extracting the frequency F in the braking force frequency domain signal_fThe phase angle of (d), f is 1,2,3, … …, τ, τ represents the total number of different frequencies;

s33, extracting the frequency F in the braking force frequency domain signal_fThe amplitude of (d);

s34, extracting the frequency F in the braking force frequency domain signal_fA deviation value of (d);

s35, according to the phase angle in step S32 and the amplitude in step S33The value and the deviation value in step S34 are obtained as F_fThe braking force curve of (d);

and S35, fitting the braking force curve according to the braking force curves with different frequencies to form a braking force fitting curve.

8. The data processing method of a commercial vehicle disc brake assembly BTV according to the claim 3, characterized in that, before the step S1, the method further comprises the step S0 of converting the rotation speed of the main shaft of the brake inertia test stand with the vehicle speed or/and calculating the test rotational inertia;

the calculation method for the conversion of the main shaft rotating speed and the vehicle speed of the brake inertia test bed comprises the following steps:

n＝2.65V/r，

wherein n represents the rotation speed of the main shaft of the brake inertia test bed;

v represents a test vehicle speed;

r represents the wheel rolling radius.

The calculation method of the test rotational inertia comprises the following steps:

I＝G_mr²，

wherein I represents a calculated value of the moment of inertia;

G_mthe maximum design total mass of the automobile is distributed to the mass born by the wheel corresponding to the tested brake according to the braking force distribution ratio design value;

r represents the wheel rolling radius.

9. A method of processing data for a commercial vehicle disc brake assembly BTV according to claim 3 further comprising processing the brake disc for thermal deformation.

10. A data processing system of a commercial vehicle disc brake assembly BTV is characterized by comprising a curve data acquisition module, a curve peak detection module, a curve trough detection module, a peak number counting module, a trough number counting module, a calculation module and a display module;

the data output end of the curve data acquisition module is connected with the data input end of the curve crest detection module, the data output end of the curve crest detection module is connected with the data input end of the crest number statistic module, the data output end of the curve data input module is connected with the data input end of the curve trough detection module, the data output end of the curve trough detection module is connected with the data input end of the trough number statistic module, the data output end of the crest number statistic module is connected with the crest data input end of the calculation module, the data output end of the trough number statistic module is connected with the trough data input end of the calculation module, and the data output end of the calculation module is connected with the data input end of the display module;

the curve data acquisition module is used for acquiring a braking torque curve, the curve crest detection module is used for detecting crest positions and corresponding peak values in the braking torque curve, the curve trough detection module is used for detecting trough positions and corresponding trough values in the braking torque curve, the crest number counting module is used for counting the total number of the crests, the trough number counting module is used for counting the total number of the troughs, the calculation module is used for calculating BTV values according to the crest positions and the corresponding peak values detected by the curve crest detection module, the trough positions and the corresponding peak values detected by the curve trough detection module, the total number of the crests counted by the crest number counting module and the total number of the troughs counted by the trough number counting module, and the display module is used for displaying the braking torque curve and the BTV values.

Technical Field

The invention relates to the technical field of commercial vehicle disc brake assembly braking torque fluctuation (BTV), in particular to a method for measuring and processing data of the BTV of a commercial vehicle disc brake assembly.

Background

From the perspective of the subjective evaluation of the whole vehicle, the comfort of braking is an important index of the driving experience, and the comfort of driving is directly influenced by the problem of shaking in the braking process. From the excitation source, the problem of jitter in the braking process is mainly caused by braking pressure fluctuation and braking torque fluctuation; the brake torque is generated in the brake, and the shaking caused by the fluctuation of the brake torque is transmitted to the vehicle body and the steering system through the suspension system, so that the driving feeling is influenced. It can be seen that the measurement of the braking torque fluctuations of a disk brake assembly is particularly important in a model test of the latter.

Disclosure of Invention

The invention aims to at least solve the technical problems in the prior art, and particularly creatively provides a method for measuring and processing data of a commercial vehicle disc brake assembly BTV.

In order to achieve the aim, the invention provides a measuring system of a commercial vehicle disc brake assembly BTV, which comprises a brake inertia test bed, a force sensor for measuring braking force generated by a brake, a speed sensor for measuring the speed of a brake disc, an acceleration sensor for measuring the acceleration of the brake disc, a pressurizer for pressurizing a brake pipeline, a temperature sensor for measuring the temperature of the brake disc, a controller and a timer, wherein the brake inertia test bed is used for measuring the braking force generated by the brake;

the force data output end of the force sensor is connected with the force data input end of the controller, the speed data output end of the speed sensor is connected with the speed data output end of the controller, the speed data output end of the acceleration sensor is connected with the acceleration data output end of the controller, the temperature data output end of the temperature sensor is connected with the temperature data input end of the controller, the pressurization/decompression data output end of the controller is connected with the pressurization/decompression data input end of the pressurizer, the pressure data output end of the pressurizer is connected with the pressure data input end of the controller, the starting timing data output end of the controller is connected with the starting timing data input end of the timer, the stopping timing data output end of the controller is connected with the stopping timing data input end of the timer, and the timing data output end of the timer is connected with the timing data input end of the controller;

the controller acquires the BTV value according to data measured by one or any combination of a force sensor, a speed sensor, an acceleration sensor, a pressurizer, a temperature sensor and a timer.

In a preferred embodiment of the present invention, the present invention further comprises a support frame, wherein the support frame is provided with an installation plate, the installation plate is provided with a speed sensor fixing installation seat for fixedly installing a speed sensor, the installation plate is provided with an acceleration sensor fixing installation seat for fixedly installing an acceleration sensor, and the installation plate is provided with a temperature sensor fixing installation seat for fixedly installing a temperature sensor;

the speed sensor is fixedly installed on the speed sensor fixed installation seat, the acceleration sensor is fixedly installed on the acceleration sensor fixed installation seat, and the temperature sensor is fixedly installed on the temperature sensor fixed installation seat.

The invention also discloses a data processing method of the commercial vehicle disc brake assembly BTV, which comprises the following steps:

s1, the controller judges whether the rotating speed of the brake disc reaches a preset initial speed threshold value:

if the rotating speed of the brake disc reaches the preset initial speed threshold, the brake disc keeps rotating at the preset initial speed threshold, and step S2 is executed;

if the rotating speed of the brake disc is higher than the preset initial speed threshold, the controller sends a control signal to the brake inertia test bed of the brake inertia test bed, controls the rotating speed of the brake disc to be reduced, enables the rotating speed of the brake disc to be equal to the preset initial speed threshold, and returns to the step S1;

if the rotating speed of the brake disc is lower than the preset initial speed threshold, the controller sends a control signal to the brake inertia test bed of the brake inertia test bed, controls the rotating speed of the brake disc to be increased, enables the rotating speed of the brake disc to be equal to the preset initial speed threshold, and returns to the step S1;

s2, the controller sends a control signal to the pressurizer, and the pressurizer pressurizes the brake pipeline to enable the acceleration detected by the acceleration sensor to be a preset acceleration threshold value;

when the pressure value input by the pressurizer to the brake pipeline is equal to a preset pressure threshold value and the duration time is greater than or equal to a preset time threshold value, the controller sends a timing starting control signal to the timer of the pressurizer, and the timer records that the time is t 1;

when the controller receives that the speed detected by the speed sensor is smaller than or equal to a preset speed threshold value, the preset speed threshold value is smaller than a preset initial speed threshold value, the controller sends a timing stopping control signal to a timer of the controller, and the timer records that the time is t 2;

s3, obtaining the braking force generated by the brake and detected by the force sensor at the time period of t 1-t 2, fitting the braking force according to the time period of t 1-t 2 to obtain a braking force fitting curve, and obtaining a braking torque curve through the braking force fitting curve;

and S4, obtaining the BTV value according to the brake torque curve.

In a preferred embodiment of the present invention, in step S4, the method for calculating the BTV value includes the steps of:

s41, numbering all wave crests and wave troughs on the braking torque curve in sequence, wherein the wave crests and the wave troughs are respectively X₁、X₂、X₃、……、X_x，Y₁、Y₂、Y₃、……、Y_yWherein X represents the total number of peaks, y represents the total number of valleys, and X₁Denotes the 1 st peak, X₂Denotes the 2 nd peak, X₃Denotes the 3 rd peak, X_xDenotes the x peak, Y₁Denotes the 1 st trough, Y₂Denotes the 2 nd trough, Y₃Denotes the 3 rd trough, Y_yRepresents the y trough;

s42, acquiring adjacent peak-valley difference values of adjacent peaks and valleys;

and S43, obtaining a BTV value according to the difference value of adjacent peaks and valleys.

In a preferred embodiment of the present invention, in step S42, the method for calculating the difference between adjacent peaks and valleys is:

wherein, | | represents taking an absolute value;

representing a braking torque value corresponding to the v peak; v ∈ {1,2,3,..., x };

V_v,δrepresenting the adjacent peak-to-valley difference.

In a preferred embodiment of the present invention, in step S43, the BTV value is calculated by:

wherein, V_v,δRepresenting adjacent peak-to-valley difference values;

x represents the total number of peaks;

y represents the total number of troughs;

V_avgthe BTV value is shown.

In a preferred embodiment of the present invention, in step S3, the braking torque curve is calculated by:

wherein the content of the first and second substances,representing a braking force fitting curve;

f represents the moment arm value;

the braking torque curve is shown.

In a preferred embodiment of the present invention, in step S3, the method for obtaining a braking force fitting curve through braking force fitting includes the steps of:

s31, carrying out fast Fourier transform on the braking force in the time period from t1 to t2 to obtain a braking force frequency domain signal;

s32, extracting the frequency F in the braking force frequency domain signal_fThe phase angle of (d), f is 1,2,3, … …, τ, τ represents the total number of different frequencies;

s33, extracting the frequency F in the braking force frequency domain signal_fThe amplitude of (d);

s34, extracting the frequency F in the braking force frequency domain signal_fA deviation value of (d);

s35, obtaining a frequency F according to the phase angle in the step S32, the amplitude in the step S33 and the deviation value in the step S34_fThe braking force curve of (d);

and S35, fitting the braking force curve according to the braking force curves with different frequencies to form a braking force fitting curve.

In a preferred embodiment of the present invention, step S0 is further included before step S1, and the method includes converting the rotation speed of the main shaft of the brake inertia test stand with the vehicle speed or/and calculating the test moment of inertia;

the calculation method for the conversion of the main shaft rotating speed and the vehicle speed of the brake inertia test bed comprises the following steps:

n＝2.65V/r，

wherein n represents the rotation speed of the main shaft of the brake inertia test bed;

v represents a test vehicle speed;

r represents the wheel rolling radius.

The calculation method of the test rotational inertia comprises the following steps:

I＝G_mr²，

wherein I represents a calculated value of the moment of inertia;

G_mthe maximum design total mass of the automobile is distributed to the mass born by the wheel corresponding to the tested brake according to the braking force distribution ratio design value;

r represents the wheel rolling radius.

In a preferred embodiment of the invention, the method further comprises the step of treating the brake disc in a hot deformation mode.

The invention also discloses a data processing system of the commercial vehicle disc brake assembly BTV, which comprises a curve data acquisition module, a curve peak detection module, a curve trough detection module, a peak number counting module, a trough number counting module, a calculation module and a display module;

the data output end of the curve data acquisition module is connected with the data input end of the curve crest detection module, the data output end of the curve crest detection module is connected with the data input end of the crest number statistic module, the data output end of the curve data input module is connected with the data input end of the curve trough detection module, the data output end of the curve trough detection module is connected with the data input end of the trough number statistic module, the data output end of the crest number statistic module is connected with the crest data input end of the calculation module, the data output end of the trough number statistic module is connected with the trough data input end of the calculation module, and the data output end of the calculation module is connected with the data input end of the display module;

the curve data acquisition module is used for acquiring a braking torque curve, the curve crest detection module is used for detecting crest positions and corresponding peak values in the braking torque curve, the curve trough detection module is used for detecting trough positions and corresponding trough values in the braking torque curve, the crest number counting module is used for counting the total number of the crests, the trough number counting module is used for counting the total number of the troughs, the calculation module is used for calculating BTV values according to the crest positions and the corresponding peak values detected by the curve crest detection module, the trough positions and the corresponding peak values detected by the curve trough detection module, the total number of the crests counted by the crest number counting module and the total number of the troughs counted by the trough number counting module, and the display module is used for displaying the braking torque curve and the BTV values.

In conclusion, due to the adoption of the technical scheme, the BTV value can be measured.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

FIG. 1 is a graphical representation of a BTV measurement profile for a disc brake assembly according to the present invention.

FIG. 2 is a schematic diagram of the initial test curve for BTV of the present invention.

FIG. 3 is a schematic diagram of the BTV curve and the test results of the present invention.

FIG. 4 is a schematic diagram of the thermal deformation testing principle of the brake disc of the present invention.

FIG. 5 is a schematic view showing the measurement position of the displacement sensor in the thermal deformation test according to the present invention.

FIG. 6 is a schematic view of the displacement curve measured in the cold state of the present invention.

FIG. 7 is a graph showing the displacement curve measured in the thermal state of the present invention.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.

The invention provides a measuring system of a commercial vehicle disc brake assembly BTV, which comprises a brake inertia test bed, a force sensor for measuring braking force generated by a brake, a speed sensor for measuring the speed of a brake disc, an acceleration sensor for measuring the acceleration of the brake disc, a pressurizer for pressurizing a brake pipeline, a temperature sensor for measuring the temperature of the brake disc, a controller and a timer, wherein the brake inertia test bed is used for measuring the braking force generated by the brake;

the force data output end of the force sensor is connected with the force data input end of the controller, the speed data output end of the speed sensor is connected with the speed data output end of the controller, the speed data output end of the acceleration sensor is connected with the acceleration data output end of the controller, the temperature data output end of the temperature sensor is connected with the temperature data input end of the controller, the pressurization/decompression data output end of the controller is connected with the pressurization/decompression data input end of the pressurizer, the pressure data output end of the pressurizer is connected with the pressure data input end of the controller, the starting timing data output end of the controller is connected with the starting timing data input end of the timer, the stopping timing data output end of the controller is connected with the stopping timing data input end of the timer, and the timing data output end of the timer is connected with the timing data input end of the controller;

the controller acquires the BTV value according to data measured by one or any combination of a force sensor, a speed sensor, an acceleration sensor, a pressurizer, a temperature sensor and a timer. And sending out audible and visual alarm by the controller according to the fact that the obtained BTV value is larger than or equal to the preset BTV threshold value, and reminding workers of paying attention to the test state.

In a preferred embodiment of the present invention, the present invention further comprises a support frame, wherein the support frame is provided with an installation plate, the installation plate is provided with a speed sensor fixing installation seat for fixedly installing a speed sensor, the installation plate is provided with an acceleration sensor fixing installation seat for fixedly installing an acceleration sensor, and the installation plate is provided with a temperature sensor fixing installation seat for fixedly installing a temperature sensor;

the speed sensor is fixedly installed on the speed sensor fixed installation seat, the acceleration sensor is fixedly installed on the acceleration sensor fixed installation seat, and the temperature sensor is fixedly installed on the temperature sensor fixed installation seat.

The invention also discloses a data processing method of the commercial vehicle disc brake assembly BTV, which comprises the following steps:

s1, the controller judges whether the rotating speed of the brake disc reaches a preset initial speed threshold value:

if the rotating speed of the brake disc reaches the preset initial speed threshold, the brake disc keeps rotating at the preset initial speed threshold, and step S2 is executed;

if the rotating speed of the brake disc is higher than the preset initial speed threshold, the controller sends a control signal to the brake inertia test bed of the brake inertia test bed, controls the rotating speed of the brake disc to be reduced, enables the rotating speed of the brake disc to be equal to the preset initial speed threshold, and returns to the step S1;

if the rotating speed of the brake disc is lower than the preset initial speed threshold, the controller sends a control signal to the brake inertia test bed of the brake inertia test bed, controls the rotating speed of the brake disc to be increased, enables the rotating speed of the brake disc to be equal to the preset initial speed threshold, and returns to the step S1;

s2, the controller sends a control signal to the pressurizer, and the pressurizer pressurizes the brake pipeline to enable the acceleration detected by the acceleration sensor to be a preset acceleration threshold value;

when the pressure value input by the pressurizer to the brake pipeline is equal to a preset pressure threshold value and the duration time is greater than or equal to a preset time threshold value, the controller sends a timing starting control signal to the timer of the pressurizer, and the timer records that the time is t 1;

when the controller receives that the speed detected by the speed sensor is smaller than or equal to a preset speed threshold value, the preset speed threshold value is smaller than a preset initial speed threshold value, the controller sends a timing stopping control signal to a timer of the controller, and the timer records that the time is t 2;

s3, obtaining the braking force generated by the brake and detected by the force sensor at the time period of t 1-t 2, fitting the braking force according to the time period of t 1-t 2 to obtain a braking force fitting curve, and obtaining a braking torque curve through the braking force fitting curve;

and S4, obtaining the BTV value according to the brake torque curve.

In a preferred embodiment of the present invention, in step S4, the method for calculating the BTV value includes the steps of:

s41, numbering all wave crests and wave troughs on the braking torque curve in sequence, wherein the wave crests and the wave troughs are respectively X₁、X₂、X₃、……、X_x，Y₁、Y₂、Y₃、……、Y_yWherein X represents the total number of peaks, y represents the total number of valleys, and X₁Denotes the 1 st peak, X₂Denotes the 2 nd peak, X₃Denotes the 3 rd peak, X_xDenotes the x peak, Y₁Denotes the 1 st trough, Y₂Denotes the 2 nd trough, Y₃Denotes the 3 rd trough, Y_yRepresents the y trough;

s42, acquiring adjacent peak-valley difference values of adjacent peaks and valleys;

and S43, obtaining a BTV value according to the difference value of adjacent peaks and valleys.

In a preferred embodiment of the present invention, in step S42, the method for calculating the difference between adjacent peaks and valleys is:

wherein, | | represents taking an absolute value;

representing a braking torque value corresponding to the v peak; v ∈ {1,2,3,..., x };

representing the braking torque value corresponding to the delta wave crest; δ ∈ {1,2,3,..., y };

o denotes a neighborhood relationship;

V_v,δrepresenting the adjacent peak-to-valley difference.

In a preferred embodiment of the present invention, in step S43, the BTV value is calculated by:

wherein, V_v,δRepresenting adjacent peak-to-valley difference values;

x represents the total number of peaks;

y represents the total number of troughs;

V_avgthe BTV value is shown.

In a preferred embodiment of the present invention, in step S3, the braking torque curve is calculated by:

wherein the content of the first and second substances,representing a braking force fitting curve;

f represents the moment arm value;

the braking torque curve is shown.

In a preferred embodiment of the present invention, in step S3, the method for obtaining a braking force fitting curve through braking force fitting includes the steps of:

s31, carrying out fast Fourier transform on the braking force in the time period from t1 to t2 to obtain a braking force frequency domain signal; the method for calculating the braking force frequency domain signal comprises the following steps:

wherein the FFT represents a fast Fourier transform algorithm;

k braking force values in a time period from t1 to t2 are input into a fast Fourier transform algorithm and are transformed into frequency domain signals;

h represents a braking force frequency domain signal;

s32, extracting the frequency F in the braking force frequency domain signal_fThe phase angle (f) is 1,2,3, … …, τ, τ represents the total number of different frequencies, and the phase angle is calculated by:

Pa_f＝angle(F_f)，

wherein, F_fRepresents a frequency;

angle () represents a phase angle extraction algorithm;

Pa_frepresents a phase angle;

s33, extracting the frequency F in the braking force frequency domain signal_fThe amplitude of (d); method for calculating amplitude value thereofComprises the following steps:

Am_f＝Amplitude Algorithm(F_f)，

wherein, F_fIndicates the frequency, f is 1,2,3, … …, tau indicates the total number of different frequencies;

amplitude Algorithm () represents an Amplitude extraction Algorithm;

Am_frepresenting an amplitude value;

s34, extracting the frequency F in the braking force frequency domain signal_fA deviation value of (d); the calculation method of the deviation value comprises the following steps:

De_f＝Distance Algorithm(F_f)，

wherein Distance Algorithm () represents a deviation degree extraction Algorithm;

F_findicates the frequency, f is 1,2,3, … …, tau indicates the total number of different frequencies;

De_frepresents a deviation value;

s35, obtaining a frequency F according to the phase angle in the step S32, the amplitude in the step S33 and the deviation value in the step S34_fBraking force curve of frequency F_fThe expression of the braking force curve of (a) is:

wherein Am is_fRepresenting an amplitude value;

F_findicates the frequency, f is 1,2,3, … …, tau indicates the total number of different frequencies;

Pa_frepresents a phase angle;

De_frepresents a deviation value;

representing a frequency of F_fThe braking force curve of (d);

t represents a time;

s35, fitting the braking force curves with different frequencies into a braking force fitting curve, wherein the calculation method for fitting the braking force curves with different frequencies into the braking force fitting curve comprises the following steps:

wherein the content of the first and second substances,representing a frequency of F₁The braking force curve of (d);

representing a frequency of F₂The braking force curve of (d);

representing a frequency of F₃The braking force curve of (d);

representing a frequency of F_τThe braking force curve of (d); f₁≠F₂≠F₃≠…F_τ；

A brake force fit curve is shown.

In a preferred embodiment of the present invention, step S0 is further included before step S1, and the method includes converting the rotation speed of the main shaft of the brake inertia test stand with the vehicle speed or/and calculating the test moment of inertia;

the calculation method for the conversion of the main shaft rotating speed and the vehicle speed of the brake inertia test bed comprises the following steps:

n＝2.65V/r，

wherein n represents the rotation speed of the main shaft of the brake inertia test bed;

v represents a test vehicle speed;

r represents the wheel rolling radius.

The calculation method of the test rotational inertia comprises the following steps:

I＝G_mr²，

wherein I represents a calculated value of the moment of inertia;

G_mthe maximum design total mass of the automobile is distributed to the mass born by the wheel corresponding to the tested brake according to the braking force distribution ratio design value;

r represents the wheel rolling radius.

1. Simulation of BTV (brake torque vector) braking condition of disc brake assembly by using brake inertia rack

Mounting a commercial vehicle disc brake assembly on an inertia test bench according to the actual vehicle mounting requirement, and calculating rotational inertia according to the total full-load mass of the vehicle, the braking force distribution ratio and the whole bridge bearing load; the BTV braking condition of the disc brake assembly is simulated by controlling the rotating speed of the motor and the pressure of the brake pipe.

1.1 measurement principle of brake torque fluctuation of commercial vehicle disc brake assembly

The brake torque fluctuation of the disc brake assembly, referred to as "assembly BTV" for short, refers to the maximum difference between adjacent peaks and troughs of the brake torque in the effective braking time in the braking process, expressed in Nm units. The disc brake assembly BTV test curve is shown in fig. 1.

The BTV measurement curve of the disc brake assembly shown in fig. 1 reflects the time-dependent changes in brake line pressure, brake torque, and vehicle speed during a single braking event. The effective braking time in the primary braking process refers to the time from 0.3s after the braking pressure reaches the given pressure to the time when the vehicle speed reaches 10 km/h. And (3) keeping the pressure of a brake pipeline constant in the braking process, ensuring that the braking torque can fluctuate up and down, and finding out the average value of the difference values of adjacent wave crests and wave troughs of the braking torque in the effective braking time, namely the braking torque fluctuation in the braking process.

1.2 preparation of the test

1.2.1 calculation of the rotational speed of the test bed spindle

The rotating speed of a main shaft of the brake inertia test bed and the vehicle speed are converted according to the following relation:

n 2.65V/r (formula 1)

In formula 1:

n is the main shaft rotating speed of the brake inertia test bed, and the unit rotation per minute is r/min;

v is the test vehicle speed, and the unit kilometer per hour is km/h;

r is the rolling radius of the wheel, and the unit meter is m.

1.2.2 calculation of test moment of inertia

The experimental moment of inertia is calculated as follows:

I＝G_mr²(formula 2)

In formula 2:

i-calculated value of moment of inertia in kg.m²；

G_mDistributing the maximum designed total mass of the automobile to the part of the mass born by the wheels corresponding to the tested brake according to the braking force distribution ratio design value in unit kg;

r-rolling radius of wheel, unit m.

1.3 specification of test conditions

1.3.1 run-in test

(a) The initial braking speed is 50 km/h;

(b) the test cooling air speed is 11m/s, and the temperature of the cooling air is room temperature;

(c) the pressure of a brake pipeline is adjusted to ensure that the brake deceleration reaches 3m/s²Braking from the initial braking speed to the final speed of zero;

(d) the braking interval time is determined by controlling the initial temperature of the brake not to exceed 120 ℃;

(e) the number of running-ins is determined such that the contact area between the brake lining and the brake disc reaches 80% or more.

1.3.2 disk brake Assembly BTV verification test

The assembly BTV test was performed as in table 1;

TABLE 1 BTV test sequence

1.4 gantry simulation brake Process

The disc brake assembly is installed on a commercial vehicle brake inertia test bed to realize the measurement of the commercial vehicle disc brake assembly BTV, and a K-type thermocouple (the temperature measuring range is minus 40 ℃ to 1300 ℃) is installed on the effective friction radius of the outer friction plate, and the distance between the surface of the thermocouple (temperature sensor) and the surface of the friction plate is about 0.5mm to 1 mm. The brake disc is connected to a direct current motor through a middle support and a transmission shaft, wherein the motor is used for simulating the rotating speed of a wheel, and the flywheel disc is used for simulating the load borne by the disc brake assembly. The fixed end of the brake assembly is connected to a tailstock of the commercial vehicle inertia test bench, and a force arm on the tailstock is connected with the force sensor; in the braking process, the braking force generated by the brake is transmitted to the force sensor through the force arm, and the product of the testing value of the force sensor and the force arm is the braking torque in the test.

Taking a set of BTV raw data measured by a certain commercial vehicle air disc brake as an example, an initial BTV test curve is shown in fig. 2. The BTV data processing and steps are as follows:

determining a starting point t1 of an effective braking time of the BTV data according to the time and pipe pressure data;

determining the end point t2 of the effective braking time of the BTV data according to the time and the vehicle speed data;

from the time, the braking torque data within the active braking time, i.e. between the time start point t1 and the end point t2, are identified. Then calculating the maximum torque difference value of the adjacent wave crests and wave troughs of the identified braking torque data, and then counting the average value V_avgAnd the average value V is_avgThe BTV value tested for the set of air disc brake assemblies.

The invention also discloses a data processing system of the commercial vehicle disc brake assembly BTV, which comprises a curve data acquisition module, a curve peak detection module, a curve trough detection module, a peak number counting module, a trough number counting module, a calculation module and a display module;

the data output end of the curve data acquisition module is connected with the data input end of the curve crest detection module, the data output end of the curve crest detection module is connected with the data input end of the crest number statistic module, the data output end of the curve data input module is connected with the data input end of the curve trough detection module, the data output end of the curve trough detection module is connected with the data input end of the trough number statistic module, the data output end of the crest number statistic module is connected with the crest data input end of the calculation module, the data output end of the trough number statistic module is connected with the trough data input end of the calculation module, and the data output end of the calculation module is connected with the data input end of the display module;

the curve data acquisition module is used for acquiring a braking torque curve, the curve crest detection module is used for detecting crest positions and corresponding peak values in the braking torque curve, the curve trough detection module is used for detecting trough positions and corresponding trough values in the braking torque curve, the crest number counting module is used for counting the total number of the crests, the trough number counting module is used for counting the total number of the troughs, the calculation module is used for calculating BTV values according to the crest positions and the corresponding peak values detected by the curve crest detection module, the trough positions and the corresponding peak values detected by the curve trough detection module, the total number of the crests counted by the crest number counting module and the total number of the troughs counted by the trough number counting module, and the display module is used for displaying the braking torque curve and the BTV values. The BTV curve and the test results are shown in fig. 3.

In a preferred embodiment of the invention, the method further comprises the step of treating the brake disc in a hot deformation mode. Specifically, the invention discloses a system for measuring the thermal deformation of a brake disc, which comprises a brake inertia test bed and 1 group of displacement sensors or 2 groups of displacement sensors;

the speed sensor is used for measuring the rotation speed of the brake disc, the acceleration sensor is used for measuring the acceleration of the brake disc, and the temperature sensor is used for measuring the temperature of the brake disc;

the speed data output end of the speed sensor is connected with the speed data input end of the controller, the acceleration data output end of the acceleration sensor is connected with the acceleration input end of the controller, and the temperature data output end of the temperature sensor is connected with the temperature data input end of the controller;

when the displacement sensor is 1 group of displacement sensors, the displacement sensor comprises M displacement sensors, wherein M is a positive integer greater than or equal to 2 and is respectively a 1 st displacement sensor, a 2 nd displacement sensor, a 3 rd displacement sensor, … … and an Mth displacement sensor; the displacement data output end of the zeta-th displacement sensor is connected with the displacement data input zeta-th end of the controller, zeta is a positive integer less than or equal to M (at the moment, the displacement data output end of the 1 st displacement sensor is connected with the displacement data input 1 st end of the controller, the displacement data output end of the 2 nd displacement sensor is connected with the displacement data input 2 nd end of the controller, the displacement data output end of the 3 rd displacement sensor is connected with the displacement data input 3 rd end of the controller, … …, and the displacement data output end of the Mth displacement sensor is connected with the displacement data input Mth end of the controller);

when the displacement sensors are 2 groups of displacement sensors, the displacement sensors are respectively a 1 st group of displacement sensor and a 2 nd group of displacement sensor, the 1 st group of displacement sensor comprises M displacement sensors, M is a positive integer greater than or equal to 2 and is respectively a 1 st displacement sensor, a 2 nd displacement sensor, a 3 rd displacement sensor, … … and an Mth displacement sensor, the 2 nd group of displacement sensor comprises N displacement sensors, N is a positive integer greater than or equal to 2 and is respectively an M +1 th displacement sensor, an M +2 th displacement sensor, an M +3 th displacement sensor, … … and an M + N th displacement sensor; the displacement data output end of the zeta-th displacement sensor is connected with the zeta-th displacement data input end of the controller, zeta is a positive integer less than or equal to M + N (at this time, the displacement data output end of the 1 st displacement sensor is connected with the 1 st displacement data input end of the controller, the displacement data output end of the 2 nd displacement sensor is connected with the 2 nd displacement data input end of the controller, the displacement data output end of the 3 rd displacement sensor is connected with the 3 rd displacement data input end of the controller, … …, the displacement data output end of the M + N displacement sensor is connected with the M + N displacement data input end of the controller, when 2 is taken at M, N, the displacement data output end of the 1 st displacement sensor is connected with the 1 st displacement data input end of the controller, and the displacement data output end of the 2 nd displacement sensor is connected with the 2 nd displacement data input end of the controller, the displacement data output end of the 3 rd displacement sensor is connected with the 3 rd end of the displacement data input of the controller, and the displacement data output end of the 4 th displacement sensor is connected with the 4 th end of the displacement data input of the controller. ) (ii) a Preferably, when M is 2, the 1 st group of displacement sensors includes 2 displacement sensors, which are the 1 st displacement sensor (non-contact displacement sensor 1) and the 2 nd displacement sensor (non-contact displacement sensor 2), respectively, and the 2 nd group of displacement sensors includes 2 displacement sensors, which are the 3 rd displacement sensor (non-contact displacement sensor 3) and the 4 th displacement sensor (non-contact displacement sensor 4), respectively;

the controller judges the thermal deformation of the brake disc according to data measured by the speed sensor, the acceleration sensor, the temperature sensor and 1 group of displacement sensors or 2 groups of displacement sensors. According to the invention, according to whether the measured thermal deformation is greater than or equal to the preset thermal deformation threshold value or not, if the measured thermal deformation is greater than or equal to the preset thermal deformation threshold value, the controller sends out a warning to the working personnel, wherein the warning can be an audible and visual alarm or a short message, so that the working personnel can be reminded in time; after the test was stopped, the generated temperature-heat distortion curve was stored in the test database as a picture.

In a preferred embodiment of the invention, 1 set of displacement sensors is located on one side of the brake disc;

the 1 st group of the 2 groups of displacement sensors is located on one side of the brake disc and the 2 nd group of the 2 groups of displacement sensors is located on the other side of the brake disc.

In a preferred embodiment of the invention, all displacement sensors measure different points on the same radius on the brake disc.

In a preferred embodiment of the present invention, the present invention further comprises a connecting plate, a first fixing plate for fixedly mounting M displacement sensors, and a second fixing plate for fixedly mounting N displacement sensors, wherein the first fixing plate and the second fixing plate are movably disposed in parallel and vertically on the connecting plate, a parallel distance between the first fixing plate and the second fixing plate is Lmm, mm is a length unit millimeter, the first fixing plate and the second fixing plate are located on the same surface of the connecting plate, the M displacement sensors are fixedly mounted on the first fixing plate, and the N displacement sensors are fixedly mounted on the second fixing plate; the connecting plate sets up on the support frame.

In a preferred embodiment of the present invention, a speed sensor fixing mount for fixedly mounting a speed sensor is provided on the first fixing plate or the second fixing plate, and the speed sensor is fixedly mounted on the speed sensor fixing mount;

an acceleration sensor fixing installation seat for fixedly installing an acceleration sensor is arranged on the first fixing plate or the second fixing plate, and the acceleration sensor is fixedly installed on the acceleration sensor fixing installation seat;

and a temperature sensor fixing installation seat for fixedly installing a temperature sensor is arranged on the first fixing plate or the second fixing plate, and the temperature sensor is fixedly installed on the temperature sensor fixing installation seat.

The invention also discloses a data processing method for the thermal deformation of the brake disc, which comprises the following steps:

s1, starting the brake inertia test bed;

s2, measuring the displacement value of the brake disc when the brake disc is not braked by the displacement sensor to obtain the cold displacement average value of the brake disc rotating at low speed in the cold state;

s3, measuring the displacement value which reaches the condition when the brake disc is braked by the displacement sensor to obtain the average value of the thermal displacement of the brake disc in the braking process under the thermal state;

s4, obtaining an absolute deformation according to the cold state displacement average value in the step S2 and the hot state displacement average value in the step S3;

and S5, obtaining the thermal deformation amount of the brake disc according to the absolute deformation amount of the step S4. The invention can measure the thermal deformation of the brake disc. According to whether the measured thermal deformation is larger than or equal to a preset thermal deformation threshold or not, if the measured thermal deformation is larger than or equal to the preset thermal deformation threshold, the controller sends out a warning to a worker, wherein the warning can be an audible and visual alarm or a short message so as to remind the worker in time; after the test was stopped, the generated temperature-heat distortion curve was stored in the test database as a picture.

In a preferred embodiment of the present invention, the method for calculating the average value of the dynamic displacement in step S2 is:

wherein Ci_ColdThe average value of the cold state displacement of the ith displacement sensor in the cold state is shown;

Ci_coldJ represents the displacement value of the ith displacement sensor at the position j in the cold state;

J_iindicating the total number of measurement positions of the i-th displacement sensor.

In a preferred embodiment of the present invention, the calculation method of the thermal state displacement average value in step S3 is:

wherein Ci_{Heat generation}Representing the average value of the thermal state displacement of the ith displacement sensor in the thermal state; i is a positive integer less than or equal to M or M + N; (when i is M + N, C1_{Heat generation}Represents the average value of the thermal state displacement of the 1 st displacement sensor in the thermal state, C2_{Heat generation}Represents the average value of the thermal state displacement of the 2 nd displacement sensor in the thermal state, C3_{Heat generation}Represents the average thermal state displacement of the 3 rd displacement sensor in the thermal state, … …, CM + N_{Heat generation}Representing the average value of the thermal state displacement of the M + N displacement sensor in the thermal state; when i is M, C1_{Heat generation}Represents the average value of the thermal state displacement of the 1 st displacement sensor in the thermal state, C2_{Heat generation}Represents the average value of the thermal state displacement of the 2 nd displacement sensor in the thermal state, C3_{Heat generation}Indicating the average thermal state displacement of the 3 rd displacement sensor in the thermal state, … …, CM_{Heat generation}Representing the average value of the thermal state displacement of the Mth displacement sensor in the thermal state; )

Ci_{Heat generation}J represents the displacement value of the ith displacement sensor at the position j in the thermal state;

J_iindicating the total number of measurement positions of the i-th displacement sensor.

In a preferred embodiment of the present invention, the method for calculating the absolute deformation amount in step S4 is:

ΔCi＝|Ci_{heat generation}-Ci_Cold|，

Wherein Ci_{Heat generation}Representing the average value of the thermal state displacement of the ith displacement sensor in the thermal state;

Ci_coldRepresents the average value of the thermal state displacement of the ith displacement sensor in the cold state;

| represents an absolute value;

Δ Ci represents an absolute deformation amount of the i-th displacement sensor.

In a preferred embodiment of the present invention, in step S5, the method for calculating the amount of thermal deformation is:

Q＝Max(|ΔCp-ΔCq|,|ΔCp′-ΔCq′|)，

wherein Max () represents taking the maximum value;

Δ Cp represents an absolute deformation amount of the pth displacement sensor; p is a positive integer less than or equal to M;

Δ Cq represents an absolute deformation amount of the q-th displacement sensor; q is a positive integer less than or equal to M, and q is not equal to p;

Δ Cp 'represents an absolute deformation amount of the p' th displacement sensor; p' is a positive integer less than or equal to M + N and greater than M;

Δ Cq 'represents an absolute deformation amount of the q' th displacement sensor; q' is a positive integer less than or equal to M + N and greater than M; q '≠ p';

q represents the amount of thermal deformation.

The calculation method of the thermal deformation amount comprises the following steps:

Q＝Max(|ΔCp-ΔCq|)，

wherein Max () represents taking the maximum value;

Δ Cp represents an absolute deformation amount of the pth displacement sensor; p is a positive integer less than or equal to M;

Δ Cq represents an absolute deformation amount of the q-th displacement sensor; q is a positive integer less than or equal to M, and q is not equal to p;

q represents the amount of thermal deformation.

In step S1, calculation of the test moment of inertia is included, and the calculation of the test moment of inertia includes calculation of the front brake test moment of inertia or/and calculation of the rear brake test moment of inertia. Wherein:

the method for calculating the test inertia of the front brake comprises the following steps:

in the formula:

I_qcalculated value of the moment of inertia of the front brake in kg m²；

G_a-total mass in kg of vehicle fully loaded;

b-distance from center of gravity to rear axle, unit m;

h_g-height of center of gravity in m when the vehicle is fully loaded;

r-rolling radius of wheel, unit m;

l is vehicle wheel base, unit m.

The method for calculating the test inertia of the rear brake comprises the following steps:

in the formula:

I_h-calculation of the moment of inertia of the rear brake, kg · m²；

G_a-total mass of vehicle fully loaded, kg;

a-the distance from the center of gravity to the front axle, m;

h_g-height of center of gravity m when vehicle is fully loaded;

r-rolling radius of wheel, unit m;

l is vehicle wheel base, m.

1. Principle for measuring thermal deformation of brake disc

The thermal deformation of the brake disc means a phenomenon that the entire brake disc working surface is deflected in one direction by high frictional temperature during high-speed braking of the brake assembly, and is expressed in mm. The brake disc heat distortion test schematic is shown in figure 4. During the high-speed braking process of the brake, the brake disc rotates continuously, and the direct measurement of the deformation of the brake disc is not achievable, so that the mode of indirectly measuring the thermal deformation of the brake disc is needed.

In a cold state, the brake disc rotates at a low speed, and the average displacement value of the non-contact displacement sensor 1 from the brake disc is C1_ColdThe average displacement value of the non-contact displacement sensor 2 from the brake disc is C2_ColdThe average displacement value of the non-contact displacement sensor 3 from the brake disc is C3_ColdThe average displacement value of the non-contact displacement sensor 4 from the brake disc is C4_Cold。

In a hot state, the average value of the displacement of the non-contact displacement sensor 1 from the brake disc in the brake braking process is C1_{Heat generation}The average displacement value of the non-contact displacement sensor 2 from the brake disc is C2_{Heat generation}The average displacement value of the non-contact displacement sensor 3 from the brake disc is C3_{Heat generation}The average displacement value of the non-contact displacement sensor 4 from the brake disc is C4_{Heat generation}。

After the distances between the four non-contact displacement sensors and the brake disc in the cold state and the hot state are measured, the absolute deformation of the four positions of the brake disc can be calculated, and the specific arithmetic relation is as follows:

ΔC1＝|C1_{heat generation}-C1_ColdL (equation 3)

ΔC2＝|C2_{Heat generation}-C2_ColdL (equation 4)

ΔC3＝|C3_{Heat generation}-C3_ColdL (equation 5)

ΔC4＝|C4_{Heat generation}-C4_ColdL (equation 6)

After the absolute deformation of the four positions of the brake disc is measured, the larger absolute value of the subtraction of the absolute deformation of the two points on the inner side of the brake disc is compared with the absolute value of the subtraction of the absolute deformation of the two points on the outer side of the brake disc, and the specific arithmetic relation is as follows:

the amount of thermal deformation of the brake disc is Max (| Δ C1- Δ C2|, | Δ C3- Δ C4|) (formula 7)

2. Test scheme for thermal deformation of brake disc

2.1 installation requirements of non-contact Displacement sensor

A non-contact displacement sensor with the measuring range of 0 mm-2.5 mm is used in the brake disc thermal deformation test, the distance between a probe of the sensor and the brake disc is installed and controlled within the effective measuring range, the sampling frequency is 1kHz, and the measuring points are shown in figure 5, wherein the displacement sensor 2 and the displacement sensor 4 measure the inner diameter deformation of the brake disc, and the displacement sensor 1 and the displacement sensor 3 measure the outer diameter deformation of the brake disc.

TABLE 2 brake disc position definition

Inner diameter (mm)	Outer diameter (mm)
		The inner edge of the brake disc is 10mm outwards	Brake disc outer edge 10mm inwards

2.2 calculation of test moment of inertia

The experimental moment of inertia is calculated as follows:

method for calculating test inertia of front brake

In the formula:

I_qcalculated value of the moment of inertia of the front brake in kg m²；

G_a-total mass in kg of vehicle fully loaded;

b-distance from center of gravity to rear axle, unit m;

h_g-height of center of gravity in m when the vehicle is fully loaded;

r-rolling radius of wheel, unit m;

l is vehicle wheel base, unit m.

Rear brake test inertia calculation method

In the formula:

I_h-calculation of the moment of inertia of the rear brake, kg · m²；

G_a-total mass of vehicle fully loaded, kg;

a-the distance from the center of gravity to the front axle, m;

h_g-height of center of gravity m when vehicle is fully loaded;

r-rolling radius of wheel, unit m;

l is vehicle wheel base, m.

2.3 specification of test conditions

Before the thermal deformation test of the table 3, when the temperature of the brake disc reaches (50 +/-1) DEG C, the rotating speed of the main shaft is constant at 30r/min, the time of measuring data is 8s, and the average value of the displacement of each non-contact displacement sensor from the brake disc in the process that the brake disc rotates for 4 circles in a cold state is recorded; the average value of the displacement of each non-contact displacement sensor from the brake disc during the last braking of the single braking heat distortion and the continuous braking heat distortion is recorded in table 3. And then calculating the thermal deformation amount of the brake disc in single braking and continuous braking according to formulas 3 to 7.

TABLE 3 Heat distortion test sequence

Serial number	Parameter(s)	Single brake heat distortion	Continuous braking thermal deformation
				1	Initial speed of brake (km/h)	Vmax	100
2	Brake end speed (km/h)	20	20
				3	Braking deceleration (g)	0.5	0.5
4	Cooling Rate (km/h)	20	20
				5	Cooling wind speed (km/h)	2	2
6	Initial temperature per cycle brake (. degree. C.)	100	100
				7	Number of single-cycle braking	1	15
8	Number of cycles	5	3
				9	Two adjacent brake intervals(s) within a single cycle	-	45

2.4 bench test

The device for testing the thermal deformation of the brake disc is carried on a brake inertia test bed to realize the measurement of the thermal deformation of the brake disc, the surface of a thermocouple is about (0.5-1) mm away from the outer friction surface of the brake disc on the effective friction radius of the outer friction surface of the brake disc, and a K-type thermocouple is arranged (the temperature measurement range is-40 ℃ -1300 ℃). The brake disc passes through the bearing frame to be connected with the tailstock, and the displacement sensor support mounting is at the rack stiff end, and four non-contact displacement sensor require to install in the brake disc both sides according to fig. 5.

3. Data processing of brake disc thermal deformation

Taking a group of thermal deformation original data measured by a brake disc for a certain type of vehicle as an example, displacement values of four non-contact displacement sensors from the brake disc are measured respectively in a cold state and a hot state, displacement curves of the four non-contact displacement sensors from the brake disc measured in the cold state are shown in fig. 6, and displacement curves of the four non-contact displacement sensors from the brake disc measured in the hot state are shown in fig. 7.

The data measured in the cold state are as follows:

C1_cold＝1.656mm，C2_Cold＝1.404mm，C3_Cold＝1.497mm，C4_Cold＝1.376mm。

The measured data in the thermal state are as follows:

C1_{heat generation}＝2.089mm，C2_{Heat generation}＝1.656mm，C3_{Heat generation}＝0.961mm，C4_{Heat generation}＝1.059mm。

Calculating the absolute deformation of the four positions of the brake disc:

ΔC1＝|C1_{heat generation}-C1_Cold2.089-1.656 | 0.433mm

ΔC2＝|C2_{Heat generation}-C2_Cold1.656-1.404 mm 0.252mm

ΔC3＝|C3_{Heat generation}-C3_Cold0.961-1.497 | 0.536mm

ΔC3＝|C3_{Heat generation}-C3_Cold1.376-1.059 | 0.317mm

The amount of thermal deformation of the brake disc was calculated as follows:

the heat distortion amount of the brake disc is Max (| DeltaC 1-DeltaC 2|, | DeltaC 3-DeltaC 4|)

Max (I0.433-0.252I, I0.536-0.317I)

＝Max(0.181，0.219)

＝0.219mm

While embodiments of the invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.