阅读说明：本技术 车辆底盘紧固连接系统失效检测方法及装置 (Failure detection method and device for vehicle chassis fastening connection system ) 是由 叶乐舟 吴宗乐 吴东存 欧阳海 夏政邦 于 2021-08-05 设计创作，主要内容包括：本发明提供了一种车辆底盘紧固连接系统失效检测方法及装置,该方法包括以下步骤：在螺栓端部中心钻孔,将电阻式应变片固定在该孔内；检测电阻式应变片的电阻值变化量,根据电阻值变化量计算螺栓的应变值,进而根据螺栓的应变值计算出螺栓的伸长量；根据螺栓的伸长量计算螺栓对连接件的夹紧力：根据夹紧力判断底盘紧固连接系统是否失效。本发明在螺栓端部中心钻孔,并将电阻式应变片固定在该孔内,进而通过检测电阻式应变片的阻值变化,计算得到车辆底盘紧固连接系统的夹紧力,以此判断底盘紧固连接系统是否失效；如检测到连接系统失效或异常值时,及时通过向驾驶员预警或主动干预,避免造成更为严重的后果。(The invention provides a failure detection method and a device for a fastening and connecting system of a vehicle chassis, wherein the method comprises the following steps: drilling a hole in the center of the end part of the bolt, and fixing the resistance type strain gauge in the hole; detecting the resistance value variation of the resistance type strain gauge, calculating the strain value of the bolt according to the resistance value variation, and further calculating the elongation of the bolt according to the strain value of the bolt; and (3) calculating the clamping force of the bolt on the connecting piece according to the elongation of the bolt: and judging whether the chassis fastening and connecting system fails according to the clamping force. According to the invention, holes are drilled in the centers of the end parts of the bolts, the resistance type strain gauges are fixed in the holes, and then the clamping force of a vehicle chassis fastening and connecting system is calculated by detecting the resistance value change of the resistance type strain gauges, so that whether the chassis fastening and connecting system fails or not is judged; if the failure or abnormal value of the connecting system is detected, the driver is warned in time or intervened actively, so that more serious consequences are avoided.)

1. A method of detecting failure of a vehicle chassis fastening connection system, comprising the steps of:

drilling a hole in the center of the end part of the bolt, and fixing the resistance type strain gauge in the hole;

the resistance value variation of the resistance type strain gauge is detected, the strain value of the bolt is calculated according to the resistance value variation, the elongation of the bolt is calculated according to the strain value of the bolt, and the calculation formula is as follows:

in the formula, epsilon is a strain value of the bolt, delta L is an elongation of the bolt, L is an original length of the bolt, delta R is a resistance value variation of the resistance type strain gauge, R is an original resistance value of the resistance type strain gauge, and K is a strain sensitivity coefficient;

and (3) calculating the clamping force of the bolt on the connecting piece according to the elongation of the bolt:

wherein T is a tightening force, E is an elastic modulus of a bolt material, A_SIs the average cross-sectional area of the bolt;

and judging whether the chassis fastening and connecting system fails according to the clamping force.

2. The vehicle chassis fastening attachment system failure detection method of claim 1, wherein the resistive strain gage is secured within the hole with an adhesive.

3. The vehicle chassis fastening attachment system failure detection method of claim 1, wherein the bore diameter isOr

4. The vehicle chassis fastening connection system failure detection method of claim 3, wherein the bore diameter is at least M12 for a bolt size less than M12When the bolt specification is larger than M12, the hole diameter of the drilled hole is

5. The method of claim 1, wherein the resistance change of the resistive strain gauge is detected by a detector, and the detector is connected to the plurality of resistive strain gauges.

6. The method as claimed in claim 1, wherein the resistance change of the resistive strain gauge is detected by a detector, and after the resistance change is detected by the detector, the data is transmitted to the vehicle ECU through the CAN bus, and the ECU calculates the clamping force.

7. The vehicle chassis fastening system failure detection method of claim 1, wherein determining whether the chassis fastening system fails based on the clamping force comprises the steps of:

s11, when the vehicle is started, calculating the primary clamping force, and judging whether the clamping force is in a first preset range; if yes, the vehicle is started normally, and then step S13 is executed; if not, go to step S12;

s12, judging whether the clamping force is in a second preset range; if yes, the vehicle is started and the driver is reminded to maintain in time, and then step S13 is executed; if not, the vehicle is not allowed to run;

s13, recalculating the clamping force once every fixed time or when the vehicle abnormally vibrates, and judging whether the new clamping force is in a first preset range; if so, the vehicle normally runs, and then step S13 is executed; if not, go to step S14;

s14, judging whether the new clamping force is in a second preset range; if yes, reminding the driver of timely maintenance, and then executing step S13; if not, reminding the driver to search for a safe place to park.

8. The vehicle chassis fastening connection system failure detection method of claim 7, wherein the first predetermined range is within ± 10% of the defined value and the second predetermined range is within ± 30% of the defined value.

9. The method for detecting failure of fastening and connecting system of vehicle chassis according to claim 7, wherein the vehicle speed is limited to 60km/h when the driver is reminded to maintain the vehicle in time.

10. A vehicle chassis fastening connection system failure detection apparatus for implementing the vehicle chassis fastening connection system failure detection method according to any one of claims 1 to 9, comprising a detected bolt, a resistance strain gauge, a detector, an ECU;

the detected bolt is connected with a part of the chassis, and a hole is drilled in the center of the end part of the detected bolt; the resistance-type strain gauge is fixed in the hole; the resistance-type strain gauge is connected with a detector, and the detector detects the resistance value variation of the resistance-type strain gauge; the detector is connected with the ECU through a CAN bus, and the ECU calculates the clamping force.

Technical Field

The invention belongs to the field of vehicle chassis fastening and connecting systems, and particularly relates to a method and a device for detecting failure of a vehicle chassis fastening and connecting system.

Background

The automobile chassis parts are mostly connected through fasteners such as bolts and nuts, and a fastening system must provide enough clamping force so as to resist impact and vibration encountered during automobile running and ensure that the connecting system does not have abnormal functions.

In the vehicle model development and after-sale process of each host factory, excessive moment attenuation and loosening of chassis bolts occur even in connection failure, and therefore a case of large-scale vehicle recall due to failure of a fastening connection system also occurs.

Currently, each host factory mainly tests the clamping force of a fastener through a bench test and a whole vehicle endurance test, and the clamping force is used as an important basis for judging whether a fastening connection system fails or not. Through tracking and verifying clamping force, the fastening torque of enough clamping force can be provided in the solidification, and then this moment of solidification on the batch production car.

Disclosure of Invention

The invention aims to provide a method and a device for detecting the failure of a fastening and connecting system of a vehicle chassis, which can detect the clamping force of a chassis fastening piece in real time and prevent the failure of the fastening and connecting system of the vehicle chassis.

The technical scheme adopted by the invention is as follows:

a method of detecting failure of a vehicle chassis fastening connection system, comprising the steps of:

drilling a hole in the center of the end part of the bolt, and fixing the resistance type strain gauge in the hole;

the resistance value variation of the resistance type strain gauge is detected, the strain value of the bolt is calculated according to the resistance value variation, the elongation of the bolt is calculated according to the strain value of the bolt, and the calculation formula is as follows:

in the formula, epsilon is a strain value of the bolt, delta L is an elongation of the bolt, L is an original length of the bolt, delta R is a resistance value variation of the resistance type strain gauge, R is an original resistance value of the resistance type strain gauge, and K is a strain sensitivity coefficient;

and (3) calculating the clamping force of the bolt on the connecting piece according to the elongation of the bolt:

wherein T is a tightening force, E is an elastic modulus of a bolt material, A_SIs the average cross-sectional area of the bolt;

and judging whether the chassis fastening and connecting system fails according to the clamping force.

Further, an adhesive is used to secure the resistive strain gage within the aperture.

Further, the bore diameter isOr

Further, when the bolt specification is smaller than M12, the hole diameter of the drill hole isWhen the bolt specification is larger than M12, the hole diameter of the drilled hole is

Furthermore, the resistance value variation of the resistance-type strain gauge is detected by a detector, and the detector is connected with the resistance-type strain gauges.

Furthermore, the resistance value variation of the resistance-type strain gauge is detected by using a detector, after the resistance value variation is detected by the detector, data are transmitted to an ECU (electronic control unit) of the vehicle through a CAN (controller area network) bus, and the ECU calculates the clamping force.

Further, whether the chassis fastening and connecting system fails or not is judged according to the clamping force, and the method comprises the following steps:

s11, when the vehicle is started, calculating the primary clamping force, and judging whether the clamping force is in a first preset range; if yes, the vehicle is started normally, and then step S13 is executed; if not, go to step S12;

s12, judging whether the clamping force is in a second preset range; if yes, the vehicle is started and the driver is reminded to maintain in time, and then step S13 is executed; if not, the vehicle is not allowed to run;

s13, recalculating the clamping force once every fixed time or when the vehicle abnormally vibrates, and judging whether the new clamping force is in a first preset range; if so, the vehicle normally runs, and then step S13 is executed; if not, go to step S14;

s14, judging whether the new clamping force is in a second preset range; if yes, reminding the driver of timely maintenance, and then executing step S13; if not, reminding the driver to search for a safe place to park.

Further, the first predetermined range is within ± 10% of the defined value, and the second predetermined range is within ± 30% of the defined value.

Further, when the driver is reminded to maintain in time, the vehicle speed is limited to 60 km/h.

A vehicle chassis fastening connection system failure detection device for realizing the vehicle chassis fastening connection system failure detection method comprises a detected bolt, a resistance-type strain gauge, a detector and an ECU;

the detected bolt is connected with a part of the chassis, and a hole is drilled in the center of the end part of the detected bolt; the resistance-type strain gauge is fixed in the hole; the resistance-type strain gauge is connected with a detector, and the detector detects the resistance value variation of the resistance-type strain gauge; the detector is connected with the ECU through a CAN bus, and the ECU calculates the clamping force.

The invention has the beneficial effects that:

according to the invention, holes are drilled in the centers of the end parts of the bolts, the resistance type strain gauges are fixed in the holes, and then the clamping force of the vehicle chassis fastening and connecting system is calculated by detecting the resistance value change of the resistance type strain gauges, so that whether the chassis fastening and connecting system fails or not is judged. If the failure or abnormal value of the connecting system is detected, the driver is warned in time or intervened actively, so that more serious consequences are avoided.

Bolts with similar specifications can use the same strain gauge, and meanwhile, a detector can share a plurality of connection points, so that the cost increment of the whole vehicle is small.

Drawings

FIG. 1 is a schematic view of a vehicle chassis fastening system failure detection apparatus according to an embodiment of the present invention.

FIG. 2 is a flow chart of a method for detecting failure of a vehicle chassis fastening system in accordance with an embodiment of the present invention.

In the figure: 101-first connecting wire harness, 102-second connecting wire harness, 103-detector, 201-engine bracket, 202-swing arm, 203-steering knuckle.

Detailed Description

The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that it would be obvious to those skilled in the art that various changes and modifications can be made without departing from the spirit of the invention. All falling within the scope of the present invention.

The failure detection method and the device for the vehicle chassis fastening connection system can detect the fastener clamping force of key and important connection points of the vehicle chassis in real time, if the connection fails, the fastener clamping force can be immediately fed back to a driver through a vehicle machine, and the vehicle can be intelligently controlled to carry out a series of protection measures. The scheme can also meet the requirements of reliability and durability, and can be used in mass production vehicles.

The technical scheme of the invention is as follows:

1. bolt preparation

Firstly, drilling a hole in the center of the end face of the bolt head, then cleaning the inner wall of the hole, and then inserting the resistance type strain gauge into the hole of the bolt and embedding and fixing the strain gauge by using special adhesive.

According to the type of the bolt, the top of the bolt is pushedRecommended bore diameter of(bolt size less than M12) and(bolt size greater than M12). Bolts of similar specifications may use the same strain gage.

The detection principle of the resistance type strain gauge is as follows: when the metal material of the strain gauge is stressed to cause expansion, the resistance value can be increased or decreased within a certain range. Because of the foil gage is fixed in the bolt hole by special insulating cement parcel, the length change of bolt can lead to the length change of foil gage in step, and the wire is connected foil gage and detector back, and the detector can detect out the damping change of foil gage in real time. By detecting changes in resistance values, according to the formula(K is a strain sensitive coefficient and is determined by the material of the strain gauge), the strain value epsilon of the bolt can be obtained, and then the elongation delta L of the bolt can be calculated. In the bolt tightening process, the bolt is located in the elastic interval, and the tensile force borne by the bolt can be correspondingly obtained according to the elongation of the bolt, namely the clamping force provided by the bolt for the connected piece.

2. Vehicle detector fixing

The detector is typically bolted to chassis-mounting structures, such as the engine bracket, the rear bracket, and the torsion beam, to prevent the cable from loosening due to movement of the chassis assembly. In order to improve the detection efficiency and reduce the repeated utilization of resources, the arrangement position of the detector can be determined according to the distribution positions of key and important connecting points, so that the same detector can detect the bolt lengths of a plurality of connecting points in real time.

In the conventional suspension, as shown in fig. 1, 101 and 102 are both a connection harness between a bolt and a detector 103, and a damping change of a bolt strain gauge is transmitted to the detector 103 through the harness. 202 is a swing arm, 203 is a knuckle, and the swing arm 202 and the engine bracket 201, the knuckle 203 and the swing arm 202 are all connected through bolts and belong to a key connection point. The detector 103 is arranged in the middle of the engine bracket 201, and real-time detection of a plurality of connection points such as connection points of the left and right triangular arms and the bracket, connection points of the shock absorber and the steering knuckle 203, and connection points of the steering knuckle 203 and the bracket is realized through a plurality of wiring harnesses connected with the detector 103.

Arranging the wiring harness: the line of the detection circuit is confirmed in advance, and then the clamping hole is reserved in the structural member of the chassis, so that the wiring harness can be installed quickly in mass production.

3. The detector is connected with the bolt

And after the key and important connecting point fastener is screwed down according to a defined screwing process, wiring the detector and the fastener. Signal transmission: after the detector detects the change of the damping value of the strain gauge, the data is transmitted to the ECU in real time through the CAN bus, the ECU calculates the strain value of the bolt through calculation according to the variation of the damping force, further, the tension/pressure of the bolt is calculated according to the strain value of the bolt, namely the clamping force of the bolt on a connected piece is calculated, and the final calculation result and the range of the clamping force of a preset fastener are subjected to point inspection.

The formula used in the above process is as follows:

bolt strain:

bolt length change: Δ L ═ epsilon L

The bolt generates a clamping force:

in the formula, E is the elastic modulus of the material used for the bolt, MPa; a. the_SEvaluation of the sectional area of the bolt, mm²。

As shown in FIG. 1, the present invention provides a vehicle chassis fastening connection system failure detection strategy comprising the steps of:

s11, when the vehicle is started, calculating the primary clamping force, and judging whether the clamping force is in a first preset range; if yes, the vehicle is started normally, and then step S13 is executed; if not, go to step S12;

s12, judging whether the clamping force is in a second preset range; if yes, the vehicle is started and the driver is reminded to maintain in time, and then step S13 is executed; if not, the vehicle is not allowed to run;

s13, recalculating the clamping force once every fixed time or when the vehicle abnormally vibrates, and judging whether the new clamping force is in a first preset range; if so, the vehicle normally runs, and then step S13 is executed; if not, go to step S14;

s14, judging whether the new clamping force is in a second preset range; if yes, reminding the driver of timely maintenance, and then executing step S13; if not, reminding the driver to search for a safe place to park.

Further, the first predetermined range is within ± 10% of the defined value, and the second predetermined range is within ± 30% of the defined value.

Further, when the driver is reminded to maintain in time, the vehicle speed is limited to 60 km/h.

The invention also provides a failure detection device of the vehicle chassis fastening and connecting system for realizing the failure detection method of the vehicle chassis fastening and connecting system, which comprises a detected bolt, a resistance-type strain gauge, a detector and an ECU;

the detected bolt is connected with a part of the chassis, and a hole is drilled in the center of the end part of the detected bolt; the resistance-type strain gauge is fixed in the hole; the resistance-type strain gauge is connected with a detector, and the detector detects the resistance value variation of the resistance-type strain gauge; the detector is connected with the ECU through a CAN bus, and the ECU calculates the clamping force.

The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes or modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention. The embodiments and features of the embodiments of the present application may be combined with each other arbitrarily without conflict.