Device and method for acquiring real-time damping coefficient of automobile shock absorber

Abstract

The invention relates to a device and a method for acquiring a real-time damping coefficient of an automobile shock absorber. The device comprises an upper acceleration sensor, a lower acceleration sensor, a strain gauge, a data acquisition module and a data processing module. The upper acceleration sensor and the lower acceleration sensor are attached to the upper end and the lower end of the shock absorber, the strain gauge is attached to a shock absorber support, dynamic signals are collected through the data collection module and processed through the data processing module, and relative acceleration signals are obtained through signals of the upper acceleration sensor and the lower acceleration sensor. Relative speed signals of the shock absorber are obtained by analyzing and processing relative acceleration signals, the relation coefficient of structural strain and force of the shock absorber is conveniently obtained through the finite element technology, and the damping force of the shock absorber is calculated and obtained based on actually-tested strain data. Effective damping force signals F, shock absorber relative speed signals V and shock absorber real-time damping coefficients C can be rapidly obtained, and users can conveniently check and take the signals in real time.

Description

Technical Field

[0001] The invention relates to the technical field of automobile shock absorber damping monitoring, and more specifically to a device and method for obtaining a real-time damping coefficient of an automobile shock absorber. Background Art

[0002] In the actual dynamic operation of the vehicle, the shock absorber plays an important role in the vehicle vibration, vehicle motion posture and other performance. Among them, the damping coefficient is an important parameter of the shock absorber. In the field of vehicle suspension system development and adjustment, especially in the development of active suspension and real-time control of suspension status, it is necessary to know the information of the real-time damping coefficient of the shock absorber. The shock absorber is a vulnerable part of the vehicle. After a certain mileage of use, the performance of the shock absorber is prone to change or attenuation. Therefore, the damping coefficient measured when the shock absorber leaves the factory cannot meet the needs of technicians. In addition, the damping coefficient of the shock absorber affects the dynamic load of the shock absorber on the vehicle body structure, which has an important impact on the fatigue life of the structure. Therefore, how to obtain the damping coefficient in real time and establish a technical method for real-time monitoring is an important issue that needs to be tackled and solved in the development of suspension and complete vehicles. Summary of the invention

[0003] The object of the present invention is to provide a device and method for obtaining the real-time damping coefficient of a vehicle shock absorber to solve the above-mentioned problem.

[0004] The present invention adopts the following technical solution: A device for acquiring a real-time damping coefficient of an automobile shock absorber comprises an upper acceleration sensor, a lower acceleration sensor, a strain gauge, a data acquisition module and a data processing module, wherein the upper acceleration sensor is arranged at the upper end of the shock absorber, the lower acceleration sensor is arranged at the lower end of the shock absorber, the strain gauge is arranged on a shock absorber support at the lower end of the shock absorber, the data acquisition module is electrically connected to the upper acceleration sensor, the lower acceleration sensor and the strain gauge respectively, and acquires dynamic signals fed back by them, the data acquisition module is connected to the data processing module, and transmits the acquired dynamic signals to the data processing module for processing and operation to obtain result data.

[0005] Furthermore, the upper acceleration sensor and the lower acceleration sensor are capacitive sensors, and the surfaces of the upper acceleration sensor and the lower acceleration sensor are oriented parallel to the axis of the shock absorber.

[0006] Furthermore, the strain gauge is mounted at a position in the shock absorber support which is sensitive to the load and has a small strain change gradient.

[0007] Preferably, the strain gauge is mounted on a plane on a shock absorber support at the lower end of the shock absorber, and the plane is located at a peripheral plane of a fixed end of the shock absorber mounted on the shock absorber support.

[0008] Furthermore, it also includes a storage medium, which is electrically connected to the data processing module and is used to store result data.

[0009] A method for obtaining a real-time damping coefficient of a vehicle shock absorber comprises the following steps: S1. Mount the upper acceleration sensor and the lower acceleration sensor at the locations with large stiffness at the upper and lower ends of the shock absorber respectively, and the mounting surfaces of the upper acceleration sensor and the lower acceleration sensor are oriented parallel to the axis of the shock absorber.

[0010] S2. The strain gauge is mounted at a position in the shock absorber support that is sensitive to load and has a small strain gradient.

[0011] S3, the acquisition module respectively collects the upper dynamic acceleration signal a of the upper end of the shock absorber fed back by the upper acceleration sensor 1 , the lower dynamic acceleration signal a of the lower end of the shock absorber fed back by the lower acceleration sensor 2 As well as the dynamic strain signal e of the shock absorber support measuring point, a dynamic signal is formed and transmitted to the data processing module.

[0012] S4, the data processing module analyzes and processes the acceleration signal in the dynamic signal, and converts the dynamic acceleration signal a 1 Subtract the dynamic acceleration signal a 2 The relative acceleration signal a is obtained; based on the relative acceleration, the relative acceleration time domain signal a(r) is obtained, the relative acceleration time domain signal a(r) is converted into a spectrum through discrete Fourier transform, and decomposed into acceleration signal components under various frequency components; in combination with the actual working conditions of the vehicle, the integral calculation frequency band range is determined, the acceleration signal component is integrated once, and the velocity signal v(r) is obtained through inverse fast Fourier transform, and finally the shock absorber relative velocity time domain signal V is obtained.

[0013] S5. The data processing module multiplies the dynamic strain signal e in the dynamic signal by the relationship coefficient α between the shock absorber support load and the measuring point strain to obtain the shock absorber support load signal, that is, the shock absorber damping force F, that is, F=α*e.

[0014] S6. Combining the shock absorber damping force obtained above with the shock absorber relative speed, and dividing the shock absorber damping force F by the shock absorber relative speed signal V to obtain the real-time resistance coefficient C of the shock absorber, that is, C=F / V.

[0015] S7, transmitting the result data of the damping force signal F, the shock absorber relative speed signal V, and the shock absorber real-time damping coefficient C to a storage medium in real time, completing storage for real-time viewing and retrieval.

[0016] Furthermore, in step S3, the acquisition module uses a sampling rate of more than 200 Hz when acquiring signals.

[0017] Furthermore, in step S4, the calculation formula of the relative acceleration signal a is a= a 1 - a 2 Among them, when the upper acceleration sensor or the lower acceleration sensor is mounted on the shock absorber, if the orientation of the sensor is facing downward, during data processing, the dynamic acceleration signal corresponding to the sensor facing downward is multiplied by -1 before entering into the calculation formula for calculation.

[0018] Furthermore, in step S4, the relative acceleration time domain signal a(r) is transformed into a spectrum by discrete Fourier transform and decomposed into acceleration signal components under various frequency components, wherein the decomposition formula is: ; In the formula, N is the number of sampled data; k, r are 0, 1…N-1; A(k) is the Fourier transform of a(r); The acceleration signal component is integrated once, where the formula is: , in, ; In the formula, v ( r ) is the speed; f d and f u are the lower cutoff frequency and the upper cutoff frequency respectively; f is the frequency resolution; j is an imaginary unit; H ( k ) is the coefficient, which takes the value 1 for the valid calculation frequency band and takes the value 0 for the unnecessary frequency band to achieve thorough filtering.

[0019] Furthermore, in step S5, the method for obtaining the relationship coefficient α between the shock absorber support load and the measuring point strain is to first perform finite element meshing on the shock absorber support, establish a finite element model, and apply a unit load at the load input point of the shock absorber support. F 0 , its direction is from the shock absorber support to the shock absorber. In the result file, read the strain value corresponding to the measured strain position e 0 ; Unit load F 0 Divide by the strain value e 0 We get the relationship coefficient α, that is, α= F 0 / e 0 .

[0020] From the above description of the structure of the present invention, it can be seen that compared with the prior art, the present invention has the following advantages: 1. The present invention mounts acceleration sensors on the upper and lower ends of the shock absorber and strain gauges on the shock absorber support, collects dynamic signals through a data acquisition module, processes the dynamic signals through a data processing module, obtains relative acceleration signals through signals from the upper and lower acceleration sensors, obtains shock absorber relative velocity signals by analyzing and processing the relative acceleration signals, and conveniently obtains the coefficient of relationship between the shock absorber structure strain and force through finite element technology. The shock absorber damping force is calculated and obtained based on the strain data of actual tests, ensuring quick acquisition of effective damping force signals F, shock absorber relative velocity signals V, and shock absorber real-time damping coefficients C, so that users can view and use them in real time.

[0021] 2. The present invention adopts a patch-mounted capacitive acceleration sensor and a mounted strain gauge, so that the installation structure of the entire device is compact, simple and convenient, and has good operability and wide applicability.

[0022] 3. The data processing module of the present invention effectively eliminates the trend term error of the integration by filtering in the frequency domain method in addition to the acceleration signal; at the same time, in the integration process, it only needs to be converted into acceleration signal components at each frequency, and the interchange relationship between sine and cosine in the frequency domain, including phase interchange, is used to avoid the time domain signal error from being accumulated and amplified, thereby improving the accuracy of the obtained speed signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a simple schematic diagram of the structure of the device of the present invention.

[0024] The numbers in the figure are: upper acceleration sensor 11, lower acceleration sensor 12, strain gauge 20, data acquisition module 30, data processing module 40, storage medium 50, shock absorber 60 DETAILED DESCRIPTION

[0025] The specific implementation of the embodiment of the present invention is described below with reference to the accompanying drawings.

[0026] Reference Figure 1 A device for acquiring a real-time damping coefficient of a vehicle shock absorber includes an upper acceleration sensor 11, a lower acceleration sensor 12, a strain gauge 20, a data acquisition module 30, a data processing module 40 and a storage medium 50.

[0027] Reference Figure 1, the upper acceleration sensor 11 is arranged at the upper end of the shock absorber 60, and the lower acceleration sensor 12 is arranged at the lower end of the shock absorber 60. In this embodiment, the upper acceleration sensor 11 and the lower acceleration sensor 12 are capacitive sensors, and the upper acceleration sensor 11 and the lower acceleration sensor 12 are respectively arranged at the positions with large rigidity at the upper and lower ends of the shock absorber 60, and the upper acceleration sensor 11 and the lower acceleration sensor 12 are oriented parallel to the axis of the shock absorber 60.

[0028] Reference Figure 1 The strain gauge 20 is mounted on a position of the shock absorber support (not shown) which is sensitive to the load and has a small strain change gradient. Specifically, in this embodiment, the strain gauge 20 is mounted on a plane on the shock absorber support at the lower end of the shock absorber 60. The plane is located at the peripheral plane of the fixed end of the shock absorber 60 mounted on the shock absorber support. In this embodiment, it is preferably a plane 10 mm away from the fixed end where the shock absorber 60 is mounted.

[0029] The data acquisition module 30 is electrically connected to the upper acceleration sensor 11, the lower acceleration sensor 12 and the strain gauge 20 respectively, and collects the dynamic signals fed back by them, the dynamic signals including the upper dynamic acceleration signal a fed back by the upper acceleration sensor 11 1 , the lower dynamic acceleration signal a fed back by the lower acceleration sensor 12 2 And the dynamic strain signal e of the shock absorber support measuring point (the installation point where the strain gauge 20 is installed).

[0030] The data acquisition module 30 is connected to the data processing module 40, and transmits the collected dynamic signals to the data processing module 40 for processing and calculation to obtain result data. The result data includes the damping force signal F, the shock absorber relative speed signal V, and the shock absorber real-time damping coefficient C. The storage medium 50 is electrically connected to the data processing module 40 and is used to store the result data for real-time viewing and access.

[0031] Reference Figure 1 The method for using the device is as follows: A method for obtaining the real-time damping coefficient of a vehicle shock absorber, comprising the following steps: S1. The upper acceleration sensor 11 and the lower acceleration sensor 12 are respectively mounted on the upper and lower ends of the shock absorber 60 at positions with large rigidity, and the mounting surfaces of the upper acceleration sensor 11 and the lower acceleration sensor 12 are oriented parallel to the axis of the shock absorber 60.

[0032] S2. The strain gauge 20 is mounted on a position of the shock absorber support that is sensitive to the load and has a small strain gradient. The specific position is preferably the plane described above.

[0033] S3, the acquisition module respectively collects the upper dynamic acceleration signal a of the upper end of the shock absorber 60 fed back by the upper acceleration sensor 11 1, the lower dynamic acceleration signal a of the lower end of the shock absorber 60 fed back by the lower acceleration sensor 12 2 and the dynamic strain signal e of the shock absorber support measuring point, forming a dynamic signal, and transmitting it to the data processing module 40. Among them, the acquisition module adopts a sampling rate of more than 200 Hz when acquiring signals to cover vibration waveforms under various working conditions and frequencies.

[0034] S4, the data processing module 40 analyzes and processes the acceleration signal in the dynamic signal, and converts the dynamic acceleration signal a 1 Subtract the dynamic acceleration signal a 2 The relative acceleration signal a is obtained. The calculation formula of the relative acceleration signal a is a= a 1 - a 2 ; Wherein, when the upper acceleration sensor 11 or the lower acceleration sensor 12 is mounted on the shock absorber 60, if the orientation of the sensor is facing downward, then during data processing, the dynamic acceleration signal corresponding to the sensor facing downward is multiplied by -1 before entering into the calculation formula for calculation. For ease of understanding, for example: the upper acceleration sensor 11 is mounted on the upper end of the shock absorber 60 facing downward; the lower acceleration sensor 12 is mounted on the lower end of the shock absorber 60 facing upward, then, when calculating the relative acceleration signal a, the upper dynamic acceleration signal a is first obtained. 1 Multiply the value by -1; then subtract the dynamic acceleration signal a 2 The value of is obtained to obtain the relative acceleration signal a. In order to improve the accuracy of the acceleration calculation result, the present invention preferably adopts frequency method filtering.

[0035] Based on the relative acceleration, the relative acceleration time domain signal a(r) is obtained, and the relative acceleration time domain signal a(r) is converted into a spectrum through discrete Fourier transform (DFT) and decomposed into acceleration signal components under various frequency components; the decomposition formula is: ; In the formula, N is the number of sampled data; k, r are 0, 1…N-1; A(k) is the Fourier transform of a(r).

[0036] Determine the integral calculation frequency band range, integrate the acceleration signal component once, and obtain the velocity signal v(r) through the inverse fast Fourier transform (IFFT), where the formula is: , in, ; In the formula, v ( r ) is the speed; f d and fu are the lower cutoff frequency and the upper cutoff frequency respectively; f is the frequency resolution; j is an imaginary unit; H ( k ) is the coefficient, which takes the value 1 for the valid calculation frequency band and takes the value 0 for the unnecessary frequency band to achieve thorough filtering.

[0037] Combined with the actual working conditions of the car, the preferred f d 0.5Hz and f u The relative speed signal V of the shock absorber is finally obtained.

[0038] S5. The data processing module 40 multiplies the dynamic strain signal e in the dynamic signal by the relationship coefficient α between the shock absorber support load and the measuring point strain to obtain the shock absorber support load signal, that is, the damping force F of the shock absorber 60, that is, F=α*e.

[0039] The method for obtaining the relationship coefficient α between the shock absorber support load and the measuring point strain is to first divide the shock absorber support into finite element meshes, establish a finite element model, and apply a unit load at the load input point of the shock absorber support. F 0 , its direction is from the shock absorber support to the shock absorber 60, in the result file, read the strain value corresponding to the measured strain position e 0 ; Unit load F 0 Divide by the strain value e 0 We get the relationship coefficient α, that is, α= F 0 / e 0 .

[0040] S6. Combining the damping force of the shock absorber 60 obtained above with the relative speed of the shock absorber 60, and dividing the damping force F of the shock absorber 60 by the relative speed signal V of the shock absorber, to obtain the real-time resistance coefficient C of the shock absorber 60, that is, C=F / V.

[0041] S7, transmitting the result data of the damping force signal F, the shock absorber relative speed signal V, and the shock absorber real-time damping coefficient C to the storage medium 50 in real time, completing the storage, for real-time viewing and retrieval.

[0042] In summary, the present invention mounts acceleration sensors on the upper and lower ends of the shock absorber 60, mounts strain gauges 20 on the shock absorber support, collects dynamic signals through the data acquisition module 30, and processes the dynamic signals through the data processing module. Through the finite element technology, the relationship coefficient between the structural strain and force of the shock absorber 60 is conveniently obtained, and the damping force of the shock absorber 60 is calculated and obtained based on the strain data of the actual test, ensuring the quick acquisition of effective damping force signal F, shock absorber relative velocity signal V, and shock absorber real-time damping coefficient C.

[0043] The present invention proposes a device and method for obtaining the damping coefficient of the shock absorber 60 in real time. Compared with the technical method of directly installing force sensors and displacement sensors, the present invention avoids the problems of high purchase cost of force sensors and displacement sensors, insufficient space for disassembly and assembly of sensors and shock absorber 60, etc., and adopts a patch-mounted capacitive acceleration sensor and a patch-mounted strain gauge 20, so that the installation structure of the entire device is compact, simple and convenient, with good operability and wide applicability.

[0044] That is, the present invention effectively eliminates the trend term error of the integration through frequency domain filtering; at the same time, in the integration process, it only needs to be converted into acceleration signal components at each frequency, and the interchange relationship between sine and cosine in the frequency domain, including phase interchange, is used to avoid the time domain signal error from being accumulated and amplified, thereby improving the accuracy of the obtained speed signal.

[0045] The above is only a specific implementation of the present invention, but the design concept of the present invention is not limited thereto. Any non-substantial changes to the present invention using this concept shall be deemed as an infringement of the protection scope of the present invention.

Claims

1. A real-time damping coefficient acquisition device for a vehicle shock absorber, a real-time damping coefficient acquisition device for a vehicle shock absorber, characterized in that: It includes an upper acceleration sensor, a lower acceleration sensor, a strain gauge, a data acquisition module and a data processing module. The upper acceleration sensor is arranged at the upper end of the shock absorber, the lower acceleration sensor is arranged at the lower end of the shock absorber, and the strain gauge is arranged on the shock absorber support at the lower end of the shock absorber. The data acquisition module is electrically connected to the upper acceleration sensor, the lower acceleration sensor and the strain gauge respectively, and collects the dynamic signals fed back by them. The data acquisition module is connected to the data processing module, and transmits the collected dynamic signals to the data processing module for processing and operation to obtain result data.

2. The device for obtaining the real-time damping coefficient of a vehicle shock absorber according to claim 1, characterized in that: The upper acceleration sensor and the lower acceleration sensor are capacitive sensors, and the surfaces of the upper acceleration sensor and the lower acceleration sensor are oriented parallel to the axis of the shock absorber.

3. The device for obtaining the real-time damping coefficient of a vehicle shock absorber according to claim 1, characterized in that: The strain gauge is mounted on a position of the shock absorber support that is sensitive to load and has a small strain gradient.

4. The device for obtaining the real-time damping coefficient of a vehicle shock absorber according to claim 3, characterized in that: The strain gauge is mounted on a plane on a vibration absorber support at the lower end of the vibration absorber, and the plane is located at a peripheral plane of a fixed end of the vibration absorber mounted on the vibration absorber support.

5. The device for obtaining the real-time damping coefficient of a vehicle shock absorber according to claim 1, characterized in that: It also includes a storage medium, which is electrically connected to the data processing module and is used to store result data.

6. A method for obtaining the real-time damping coefficient of a vehicle shock absorber, characterized in that: The following steps are involved: S1. Mount the upper acceleration sensor and the lower acceleration sensor at the locations with large stiffness at the upper and lower ends of the shock absorber, respectively, and the surfaces of the upper acceleration sensor and the lower acceleration sensor are oriented parallel to the axis of the shock absorber; S2, the strain gauge is mounted at a position in the shock absorber support that is sensitive to load and has a small strain gradient; S3, the acquisition module respectively acquires the upper dynamic acceleration signal a1 of the upper end of the shock absorber fed back by the upper acceleration sensor, the lower dynamic acceleration signal a2 of the lower end of the shock absorber fed back by the lower acceleration sensor, and the dynamic strain signal e of the shock absorber support measuring point, forms a dynamic signal, and transmits it to the data processing module; S4, the data processing module analyzes and processes the acceleration signal in the dynamic signal, and obtains the relative acceleration signal a by subtracting the upper dynamic acceleration signal a1 from the lower dynamic acceleration signal a2; based on the relative acceleration, the relative acceleration time domain signal a(r) is obtained, and the relative acceleration time domain signal a(r) is converted into a spectrum through discrete Fourier transform, and decomposed into acceleration signal components under various frequency components; combined with the actual working conditions of the vehicle, the integral calculation frequency band range is determined, the acceleration signal component is integrated once, and the velocity signal v(r) is obtained through inverse fast Fourier transform, and finally the shock absorber relative velocity time domain signal V is obtained; S5, the data processing module multiplies the dynamic strain signal e in the dynamic signal by the relationship coefficient α between the shock absorber support load and the measuring point strain to obtain the shock absorber support load signal, that is, the shock absorber damping force F, that is, F=α*e; S6, combining the shock absorber damping force obtained above with the shock absorber relative speed, and dividing the shock absorber damping force F by the shock absorber relative speed signal V to obtain the real-time resistance coefficient C of the shock absorber, that is, C=F / V; S7, transmitting the result data of the damping force signal F, the shock absorber relative speed signal V, and the shock absorber real-time damping coefficient C to a storage medium in real time, completing storage for real-time viewing and retrieval.

7. The method for obtaining the real-time damping coefficient of a vehicle shock absorber according to claim 6, characterized in that: In step S3, the acquisition module uses a sampling rate of more than 200 Hz when acquiring signals.

8. The method for obtaining the real-time damping coefficient of a vehicle shock absorber according to claim 6, characterized in that: In step S4, the calculation formula of the relative acceleration signal a is a= a1- a2; wherein, when the upper acceleration sensor or the lower acceleration sensor is mounted on the shock absorber, if the orientation of the sensor is facing downward, during data processing, the dynamic acceleration signal corresponding to the sensor facing downward is multiplied by -1 before entering into the calculation formula for calculation.

9. The method for obtaining the real-time damping coefficient of a vehicle shock absorber according to claim 6, characterized in that: In step S4, the relative acceleration time domain signal a(r) is transformed into a spectrum by discrete Fourier transform and decomposed into acceleration signal components under various frequency components, wherein the decomposition formula is: ; In the formula, N is the number of sampled data; k, r are 0, 1…N-1; A(k) is the Fourier transform of a(r); The acceleration signal component is integrated once, where the formula is: , in, ; In the formula, v ( r ) is the speed; f d and f u are the lower cutoff frequency and the upper cutoff frequency respectively; f is the frequency resolution; j is an imaginary unit; H ( k ) is the coefficient, which takes the value 1 for the valid calculation frequency band and takes the value 0 for the unnecessary frequency band to achieve thorough filtering.

10. The method for obtaining the real-time damping coefficient of a vehicle shock absorber according to claim 6, characterized in that: In step S5, the method for obtaining the relationship coefficient α between the shock absorber support load and the measuring point strain is to first perform finite element meshing on the shock absorber support, establish a finite element model, and apply a unit load at the load input point of the shock absorber support. F 0, its direction is from the shock absorber support to the shock absorber. In the result file, read the strain value corresponding to the measured strain position e 0; Unit load F 0 divided by the strain value e 0 to get the relationship coefficient α, that is, α= F 0 / e 0.

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