Vehicle fastener detection method and system

Abstract

The invention provides a vehicle fastener detection method and system, and the method comprises the following steps: configuring a to-be-detected vehicle to be in a full-load state, and executing driving tests under different working conditions; acquiring sampling data in a working condition test process, and establishing a torque recession prediction model based on the sampling data; setting a detection torque value based on a torque recession rate output by the torque recession prediction model, applying a rotating torque of the detection torque value to the target bolt, and judging whether the target bolt rotates or not: if the target bolt rotates, generating an anomaly detection report and triggering an alarm. Sampled data corresponding to dynamic loads and environmental factors in a working condition form are obtained, a torque recession prediction model is established according to the sampled data, and differential detection threshold values are set in combination with stress distribution characteristics of a power assembly, chassis suspension and a vehicle body connection point, so that the bolt looseness detection rate and detection efficiency are improved, and the detection accuracy is improved. And the whole vehicle reliability verification period is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle detection, and in particular to a vehicle fastener detection method and system. Background Art

[0002] High-strength threaded fasteners are widely used in important joints of automobiles. As the trend of lightweighting of the entire vehicle promotes the use of lightweight materials such as aluminum alloy, some welded structures are changed to bolt connections, further enhancing the application of high-strength threaded fasteners.

[0003] In existing technologies, since loose connections may occur in various extreme working conditions and the stress forms of various vehicle systems are different, traditional component bench tests and system bench tests cannot fully cover the working conditions where thread loosening may occur. In addition, the fixed torque test corresponding to the safety factor cannot reflect the torque decay caused by dynamic loads and environmental factors in actual use, resulting in poor detection results and insufficient reliability verification. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a vehicle fastener detection method and system, aiming to solve the technical problem of poor reliability detection effect of vehicles in the prior art.

[0005] In order to achieve the above objectives, in a first aspect, the present invention provides: a vehicle fastener detection method, comprising the following steps: Configure the vehicle to be tested to a fully loaded state and perform driving tests under different working conditions; An inertial measurement unit and temperature sensors are installed at the powertrain mounting points, chassis suspension connection points, and body connection points to obtain sampled data during the operating test process and establish a torque decay prediction model based on the sampled data. A detection torque value is set based on the torque decay rate output by the torque decay prediction model. After several test cycles, a rotational torque of the detection torque value is applied to the target bolt using a digital torque wrench to determine whether the target bolt rotates. If the target bolt rotates, the current operating parameters and sampling data of the inertial measurement unit and temperature sensor are stored in real time through the vehicle-mounted OBD interface to generate an abnormality detection report.

[0006] According to one aspect of the above technical solution, after the step of determining whether the target bolt has rotated, the method further includes: If the target bolt does not rotate, continue to the next stage of testing until the reliability verification of the vehicle is completed.

[0007] According to one aspect of the above technical solution, the calculation expression of the torque decay prediction model is: ; Where, is the torque decay rate after the kth cycle, K is the number of cycles, is the working condition decay weight coefficient of the kth cycle, is the equivalent load cycle number of the kth cycle, is the normalized value of the maximum acceleration of the kth cycle, is the main frequency value of the vibration signal measured and obtained by the inertial measurement unit, is the reference frequency, is the frequency sensitivity coefficient, T is the ambient temperature obtained by the temperature sensor, is the reference temperature, is the thermal expansion coefficient parameter, is the temperature correction factor.

[0008] According to one aspect of the above technical solution, the calculation expression for setting the detection torque value based on the torque decay rate output by the torque decay prediction model is: ; Where, is the detected torque value, is the initial assembly torque value of the target bolt, is the torque decay rate of the kth cycle, is the safety attenuation factor.

[0009] According to one aspect of the above technical solution, the step of applying a rotational torque of a detection torque value to a target bolt by a digital torque wrench specifically includes: Performing weight coefficient correction on the detection torque value based on the installation area of ​​the target bolt to obtain a corrected detection torque value; Apply a rotational torque to the target bolt using a digital torque wrench to correct the detection torque value.

[0010] According to one aspect of the above technical solution, the weight coefficient of the powertrain installation point is 1.2, the weight coefficient of the chassis suspension connection point is 1, and the weight coefficient of the body connection point is 0.8.

[0011] In another aspect, the present invention provides a vehicle fastener detection system, comprising: A test module is used to configure the vehicle to be tested to a fully loaded state and perform driving tests under different working conditions; A decay prediction module is used to configure inertial measurement units and temperature sensors at powertrain mounting points, chassis suspension connection points, and body connection points to obtain sampled data during the operating test process and establish a torque decay prediction model based on the sampled data; The first detection module is configured to set a detection torque value based on the torque decay rate output by the torque decay prediction model, and after a number of test cycles, apply a rotational torque of the detection torque value to the target bolt using a digital torque wrench, and determine whether the target bolt rotates. The alarm module is used to store the current working condition parameters and the sampling data of the inertial measurement unit and the temperature sensor in real time through the vehicle-mounted OBD interface if the target bolt rotates, and generate an abnormality detection report.

[0012] According to one aspect of the above technical solution, the system further includes: The second detection module is used to continue the next stage of testing if the target bolt does not rotate until the reliability verification of the vehicle is completed.

[0013] According to one aspect of the above technical solution, the first detection module is specifically configured to: Performing weight coefficient correction on the detection torque value based on the installation area of ​​the target bolt to obtain a corrected detection torque value; Apply a rotational torque to the target bolt using a digital torque wrench to correct the detection torque value.

[0014] Compared with the existing technology, the beneficial effects of the present invention are: by obtaining sampling data corresponding to dynamic loads and environmental factors in the working condition form, and establishing a torque decay prediction model based on the sampling data, and setting differentiated detection thresholds in combination with the stress distribution characteristics of the powertrain, chassis suspension and body connection points, the detection rate and detection efficiency of bolt loosening are improved, and the reliability verification cycle of the whole vehicle is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Schematic diagram of the process of the vehicle fastener detection method in the first embodiment of the present invention; Figure 2 This is a structural block diagram of a vehicle fastener detection system according to a second embodiment of the present invention; The following specific embodiments will further illustrate the present invention in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0016] To facilitate understanding of the present invention, the present invention will be described more fully below with reference to the accompanying drawings. The drawings illustrate several embodiments of the present invention. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the present invention.

[0017] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be an intermediate element. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or there may be an intermediate element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only.

[0018] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one skilled in the art to which this invention pertains. The terms used in this specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0019] Example 1 See also Figure 1 , which is a flow chart of a vehicle fastener detection method according to a first embodiment of the present invention. As shown in the figure, the method includes the following steps: Step S100: The vehicle to be tested is configured to be fully loaded, and driving tests under different working conditions are performed.

[0020] In some application scenarios of this embodiment, the test vehicle is a new vehicle, and its condition meets the requirements of GB / T 12534 General Rules for Motor Vehicle Road Test Methods. Before the test begins, the vehicle's odometer and speedometer are calibrated and recorded, and the four-wheel alignment parameters, unladen mass, and fully laden mass are measured. The vehicle's operating condition test standards at the Xiangyang test site are as follows: 1. Vehicles must drive at a constant speed of 45 km / h through the long wave road and at a speed of 10 km / h through the twisted road.

[0021] 2. Make a U-turn north, pass the auxiliary road, then make a U-turn south, and drive at a speed of 25 km / h, crossing the bumpy and pothole-prone roads with the left and right wheels alternating.

[0022] 3. After passing the auxiliary road, turn north and drive through the bumpy road and potholes with both wheels at a speed of 25 km / h.

[0023] 4. Enter Belgium Road and drive along it for a full circle at a constant speed of 30 km / h.

[0024] 5. Enter the dust hole next to the traffic light simulation road and perform two curb impacts at a speed of 5-10 km / h. Turn around according to the road sign and then perform two curb impacts in the opposite direction.

[0025] 6. Enter a general highway and perform emergency braking three times on brake belt No. 3 and brake belt No. 4 on the general highway at an initial speed of 25 km / h, for a total of six emergency braking times.

[0026] 7. Enter the standard slope, press the brake pedal at 16.6% to stop on the slope, operate the brake pedal to make the vehicle slowly slide backward slightly, immediately pull the parking brake handle to park the vehicle, and then start on the slope to pass the 16.6% slope.

[0027] 8. Enter the square at the bottom of a standard slope, reverse 15 meters, brake to a stop at 0.2g, and then turn the steering wheel left and right at a normal speed to the limit position once each. Repeat the above test method in a cycle.

[0028] In step S200, an inertial measurement unit (IMU) and temperature sensors are deployed at the powertrain mounting points, chassis suspension connection points, and body connection points to obtain sampled data from the operating test process. A torque fade prediction model is then established based on this data. The inertial measurement unit (IMU) uses a three-axis accelerometer.

[0029] Preferably, in this embodiment, the calculation expression of the torque decay prediction model is: ; Where, is the torque decay rate after the kth cycle, K is the number of cycles, is the working condition decay weight coefficient of the kth cycle, is the equivalent load cycle number of the kth cycle, is the normalized value of the maximum acceleration of the kth cycle, is the main frequency value of the vibration signal measured and obtained by the inertial measurement unit, is the reference frequency, is the frequency sensitivity coefficient, T is the ambient temperature obtained by the temperature sensor, is the reference temperature, is the thermal expansion coefficient parameter, is the temperature correction coefficient. The weight coefficient of the working condition decay of the kth cycle is calibrated through bench test. The acceleration spectrum of different working conditions is simulated on the MTS hydraulic vibration table, and the bolt preload decay curve is recorded. The acceleration amplitude of the long wave road condition is large, and its weight coefficient is higher than that of the flat road condition. Used to quantify the cumulative effect of working conditions, the vibration signal is collected through the inertial measurement unit (IMU) and the main frequency value is extracted through FFT analysis , Used to quantify the nonlinear effect of frequency on torque decay, calibrated by material fatigue test, in this embodiment, the frequency sensitivity coefficient of the bolt is 0.023Hz −1 .

[0030] Step S300 sets a detection torque value based on the torque decay rate output by the torque decay prediction model. After several test cycles, a rotational torque corresponding to the detection torque value is applied to the target bolt using a digital torque wrench to determine whether the target bolt has rotated. Specifically, the inspection direction is the tightening direction, and the torque is slowly increased until the detection torque value is reached. If no rotation occurs, a value of "OK" is recorded; if rotation occurs, the torque at that time is recorded, along with the test data. Inspection areas include the front overhang, front axle, rear overhang, rear axle, brake body, control components, steering components, drive shaft, wheel rim nuts, engine mounts, fuel components, cooling components, exhaust components, cab mounts, transmission, and major body fasteners.

[0031] In step S400 , if the target bolt rotates, the current operating parameters and the sampling data of the inertial measurement unit and the temperature sensor are stored in real time through the vehicle-mounted OBD interface to generate an abnormality detection report.

[0032] Evaluation criteria include: Looseness of any wheel nut two or more times within every 30 cycles (an NG test); looseness of the brake disc and brake base plate mounting fasteners (if even one is loose) (an NG test); looseness of the brake wheel cylinder mounting fasteners (if even one is loose) (an NG test); and visual inspection of the brake base plate for no deformation (bend less than 1mm, twist less than 2mm). Visual inspection of the friction pad and brake backing plate for no deformation, and visual inspection of the drum brake shoe for no wavy deformation.

[0033] In summary, the vehicle fastener detection method in the above-mentioned embodiment of the present invention obtains sampled data corresponding to dynamic loads and environmental factors in the working condition form, establishes a torque decay prediction model based on the sampled data, and sets differentiated detection thresholds based on the stress distribution characteristics of the powertrain, chassis suspension, and body connection points, thereby improving the detection rate and detection efficiency of bolt loosening and reducing the vehicle reliability verification cycle.

[0034] Example 2 A second embodiment of the present application further provides a vehicle fastener detection system, which is used to implement the aforementioned embodiments and preferred embodiments. Details already described are omitted for clarity. As used below, terms such as "module," "unit," and "subunit" may refer to a combination of software and / or hardware that implements a predetermined function. While the systems described in the following embodiments are preferably implemented in software, implementation using hardware, or a combination of software and hardware, is also possible and contemplated.

[0035] like Figure 2 As shown, the system includes: a testing module 100 , a decay prediction module 200 , a first detection module 300 and an alarm module 400 .

[0036] The test module 100 is used to configure the vehicle to be tested to a fully loaded state and perform driving tests under different working conditions; The decay prediction module 200 is used to configure an inertial measurement unit and a temperature sensor at the powertrain mounting point, the chassis suspension connection point, and the body connection point to obtain sampled data during the working condition test process and establish a torque decay prediction model based on the sampled data; The first detection module 300 is used to set a detection torque value based on the torque decay rate output by the torque decay prediction model, and after several test cycles, apply a rotational torque of the detection torque value to the target bolt through a digital torque wrench to determine whether the target bolt rotates: The alarm module 400 is used to store the current working condition parameters and the sampling data of the inertial measurement unit and the temperature sensor in real time through the vehicle-mounted OBD interface if the target bolt rotates, and generate an abnormality detection report.

[0037] Preferably, in this embodiment, the system further includes: The second detection module is used to continue the next stage of testing if the target bolt does not rotate until the reliability verification of the vehicle is completed.

[0038] Preferably, in this embodiment, the first detection module 300 is specifically configured to: Performing weight coefficient correction on the detection torque value based on the installation area of ​​the target bolt to obtain a corrected detection torque value; Apply a rotational torque to the target bolt using a digital torque wrench to correct the detection torque value.

[0039] The technical features of the above-described embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0040] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art could make various modifications and improvements without departing from the spirit of the present application, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A vehicle fastener detection method, characterized in that: The following steps are involved: Configure the vehicle to be tested to a fully loaded state and perform driving tests under different working conditions; An inertial measurement unit and temperature sensors are installed at the powertrain mounting points, chassis suspension connection points, and body connection points to obtain sampled data during the operating test process and establish a torque decay prediction model based on the sampled data. A detection torque value is set based on the torque decay rate output by the torque decay prediction model. After several test cycles, a rotational torque of the detection torque value is applied to the target bolt using a digital torque wrench to determine whether the target bolt rotates. If the target bolt rotates, the current operating parameters and sampling data of the inertial measurement unit and temperature sensor are stored in real time through the vehicle-mounted OBD interface to generate an abnormality detection report.

2. The vehicle fastener detection method according to claim 1, characterized in that: After the step of determining whether the target bolt rotates, the method further includes: If the target bolt does not rotate, continue to the next stage of testing until the reliability verification of the vehicle is completed.

3. The vehicle fastener detection method according to claim 1, characterized in that: The calculation expression of the torque decay prediction model is: ； Where, is the torque decay rate after the kth cycle, K is the number of cycles, is the working condition decay weight coefficient of the kth cycle, is the equivalent load cycle number of the kth cycle, is the normalized value of the maximum acceleration of the kth cycle, is the main frequency value of the vibration signal measured and obtained by the inertial measurement unit, is the reference frequency, is the frequency sensitivity coefficient, T is the ambient temperature obtained by the temperature sensor, is the reference temperature, is the thermal expansion coefficient parameter, is the temperature correction factor.

4. The vehicle fastener detection method according to claim 3, characterized in that: The calculation expression for setting the detection torque value based on the torque decay rate output by the torque decay prediction model is: ； Where, is the detected torque value, is the initial assembly torque value of the target bolt, is the torque decay rate of the kth cycle, is the safety attenuation factor.

5. The vehicle fastener detection method according to claim 4, characterized in that: The steps of applying a rotational torque of a detection torque value to a target bolt by using a digital torque wrench specifically include: Performing weight coefficient correction on the detection torque value based on the installation area of ​​the target bolt to obtain a corrected detection torque value; Apply a rotational torque to the target bolt using a digital torque wrench to correct the detection torque value.

6. The vehicle fastener detection method according to claim 5, characterized in that: The weight coefficient of the powertrain installation point is 1.2, the weight coefficient of the chassis suspension connection point is 1, and the weight coefficient of the body connection point is 0.

8.

7. A vehicle fastener detection system, characterized in that: include: A test module is used to configure the vehicle to be tested to a fully loaded state and perform driving tests under different working conditions; A decay prediction module is used to configure inertial measurement units and temperature sensors at powertrain mounting points, chassis suspension connection points, and body connection points to obtain sampled data during the operating test process and establish a torque decay prediction model based on the sampled data; The first detection module is configured to set a detection torque value based on the torque decay rate output by the torque decay prediction model, and after a number of test cycles, apply a rotational torque of the detection torque value to the target bolt using a digital torque wrench, and determine whether the target bolt rotates. The alarm module is used to store the current working condition parameters and the sampling data of the inertial measurement unit and the temperature sensor in real time through the vehicle-mounted OBD interface if the target bolt rotates, and generate an abnormality detection report.

8. The vehicle fastener detection system according to claim 7, characterized in that: The system further comprises: The second detection module is used to continue the next stage of testing if the target bolt does not rotate until the reliability verification of the vehicle is completed.

9. The vehicle fastener detection system according to claim 7, characterized in that: The first detection module is specifically configured to: Performing weight coefficient correction on the detection torque value based on the installation area of ​​the target bolt to obtain a corrected detection torque value; Apply a rotational torque to the target bolt using a digital torque wrench to correct the detection torque value.

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