Intelligent traction pin for connecting tractor and semitrailer

Abstract

The invention discloses an intelligent traction pin for connecting a tractor and a semitrailer. The intelligent traction pin comprises a hollow traction pin body, a strain gauge bracket, a strain gauge set, anti-vibration foam and a data resolving module. The hollow traction pin is provided with a hole which is coaxial with the rotation center of the hollow traction pin and is used for accommodating a hinge force measuring element; the strain gauge bracket is a bridge between the hollow traction pin and the strain gauge group, and the strain gauge bracket is mounted in the hollow traction pin and deforms together with the hollow traction pin; the strain gauge group is attached to the strain gauge bracket and forms a differential bridge to sense the deformation of the hollow traction pin in real time; and the data resolving module resolves the voltage value output by the differential bridge and sends the calculated hinging force to the outside. According to the method, the current hinging force borne by the traction pin can be calculated according to the real-time deformation of the traction pin, and data preparation is made for intelligent algorithms such as stability control and quality identification of the semi-trailer train.

Description

Technical Field

[0001] This invention belongs to the field of intelligent connection and status monitoring technology for commercial vehicles, specifically relating to an intelligent towing pin device for semi-trailers, and more particularly to a semi-trailer and tractor connection component with integrated sensing and detection functions, which can realize real-time perception and estimation of towing pin articulation force, and is suitable for safety monitoring and intelligent operation and maintenance scenarios of heavy transport semi-trailers. Background Technology

[0002] In the intelligent semi-trailer operation system, the traction pin, as the core load-bearing component connecting the tractor and the semi-trailer, bears the crucial articulation force, a key indicator reflecting the mechanical transmission state of the connection interface between the two vehicles. It is also a critical input parameter for the semi-trailer's intelligent control program to achieve precise regulation. With the intelligent upgrade of commercial vehicles, functions such as adaptive braking and driving posture correction in semi-trailers all rely on real-time and accurate articulation force data as a basis for decision-making. When a semi-trailer is in complex conditions such as starting on an incline, emergency braking, or cornering, the articulation force will exhibit significant dynamic fluctuations. By identifying these fluctuation characteristics, the intelligent control program can quickly adjust the braking force distribution ratio of the braking system, effectively avoiding dangerous situations such as rollovers and fishtailing. Simultaneously, based on the articulation force variation pattern, the loading status of the cargo can be indirectly monitored, providing data support for operation and maintenance scheduling. However, most existing semi-trailer traction pins are purely mechanical structures, possessing only basic connection functions and unable to output articulation force parameters. This forces the intelligent control program to rely on empirical models for estimation, making it difficult to meet the safety requirements of complex transportation scenarios in terms of control accuracy and response speed.

[0003] Strain gauges are mature components for precise measurement of mechanical quantities. Their core measurement principle is based on the resistance-strain effect of metallic conductors: when a conductor undergoes elastic deformation under stress, its resistance changes systematically with the mechanical deformation, and the change in resistance exhibits a stable linear relationship with strain. After the strain gauge is tightly bonded to the stress-sensitive area of ​​the traction pin using a special adhesive, the minute elastic deformation caused by the hinge force on the traction pin is synchronously transmitted to the strain gauge. When the strain gauge is stretched, the length of the internal conductor increases and the cross-sectional area decreases, resulting in an increase in resistance; conversely, when compressed, the resistance decreases. The strain gauge is connected to a bridge circuit, which converts the resistance fluctuations into a measurable voltage signal. This signal is then processed by a data processing unit and converted into a hinge force value using calibration coefficients. This principle has been widely validated in the field of mechanical structure mechanics measurement, possessing advantages such as high measurement accuracy and strong environmental adaptability, making it perfectly suited for parameter monitoring requirements in dynamic stress scenarios of traction pins. Summary of the Invention

[0004] The purpose of this invention is to provide an intelligent towing pin for connecting a tractor and a semi-trailer, in order to solve the problems encountered in the background art.

[0005] To achieve the above objectives, the present invention provides the following solution:

[0006] A smart traction pin for connecting a tractor and a semi-trailer consists of a hollow traction pin (1), a strain gauge bracket (2), a strain gauge assembly (3), anti-vibration foam (4), and a data calculation module (5).

[0007] The hollow traction pin (1) has the same external dimensions as the standard 90 traction pin and has a square blind hole with a side length of [missing information]. The centroid is coaxial with the traction pin; the end of the blind hole extends 5 mm into the end cylinder of the traction pin; the mounting end of the hollow traction pin (1) has a threaded hole, which is coaxial with the aforementioned square blind hole; the mounting end of the hollow traction pin (1) refers to the end face used for fixing to the semi-trailer; the aforementioned square blind hole is connected to the threaded hole; the threaded hole is located at the end of the hollow traction pin (1) and forms a seal with the end cap (6); the side length of the blind hole cross section is... The following condition must be met: the strength reduction factor of the traction pin corresponding to the blind hole. Less than the threshold of the traction pin strength weakening factor The traction pin strength weakening factor The calculation formula is:

[0008]

[0009] In the formula and The diameter and length of the section where the traction pin mates with the saddle are measured in millimeters. Poisson's ratio for hollow traction pin material; The machining accuracy coefficient for a square blind hole; The uniformity coefficient of the hollow traction pin material; The fatigue coefficient of the hollow traction pin material;

[0010] The threshold of the traction pin strength weakening factor This is a critical value set to ensure that the traction pin meets the predetermined safety strength.

[0011] The strain gauge bracket (2) is a rectangular thin-walled structure, consisting of upper and lower bottom surfaces with a thickness greater than the side surfaces and partially hollowed-out side surfaces; the upper and lower bottom surfaces of the strain gauge bracket (2) form a transition fit with the blind hole of the hollow traction pin (1), if the design working condition strength coefficient The transition fit used is H7 / m6; otherwise, the transition fit used is H7 / n6. The threshold value for the working condition strength coefficient was determined to be 0.58 through experiments; the formula for calculating the design working condition strength coefficient is as follows:

[0012]

[0013] In the formula, These are the ramp frequency factor and the bump intensity factor, respectively. The weighting factors for the slope frequency factor and the bump intensity factor are 0.38 and 0.62, respectively. As a positive exponent, we take 0.7;

[0014] The strain gauge bracket (2) has a thickness of 5 mm on both the top and bottom surfaces. The blind hole mating positions with the hollow traction pin are located on the shaft sections on both sides of the mating position between the hollow traction pin and the saddle. When installing the strain gauge bracket, the hollow traction pin must be heated. There is a directional mark on the outer side of the bottom surface of the strain gauge bracket near a certain edge, indicating the front of the strain gauge bracket. Facing the bottom surface of the strain gauge bracket (2), determine the left, right and rear of the strain gauge bracket based on the front of the strain gauge bracket. When installing, the front of the strain gauge bracket should coincide with the direction of travel of the semi-trailer.

[0015] The strain gauge group (3) is divided into a longitudinal strain gauge group (311, 312) and a transverse strain gauge group (321, 322), which are installed on the strain gauge bracket (2). The longitudinal strain gauge group (311, 312) consists of a longitudinal primary strain gauge group (311) and a longitudinal secondary strain gauge group (312), and the transverse strain gauge group (321, 322) consists of a transverse primary strain gauge group (321) and a transverse secondary strain gauge group (322). Each secondary strain gauge group consists of four strain gauges. The four strain gauges of each strain gauge group form a differential bridge. The four strain gauges of each secondary strain gauge group are installed on a plane perpendicular to the axis of the hollow traction pin (1), and the distance between the plane and the installation end of the hollow traction pin (1) is [missing information]. The unit is millimeters; The subscript i is 1, representing the longitudinal strain gauge group; the subscript i is 2, representing the transverse strain gauge group; the subscript j is 1, representing the first-stage strain gauge group; the subscript j is 2, representing the second-stage strain gauge group.

[0016] The vibration damping foam (4) is a cylindrical sponge, which is composed of two layers of different materials arranged concentrically and is filled inside the strain gauge bracket (2);

[0017] The data calculation module (5) consists of a microcontroller connected to the four differential bridges. It calculates the force on the intelligent traction pin based on the output voltage value of the differential bridges. The calculation process includes:

[0018] a) Calculate the strain at each position of the hollow traction pin based on the strain gauge output voltage value. The calculation formula is as follows:

[0019]

[0020] In the formula, This is the input voltage of the differential bridge, in volts. This is the output voltage of the bridge circuit, in volts. For strain at various positions of the hollow traction pin, the definition method of the subscripts is the same as... same; The nominal sensitivity of the strain gauge is a dimensionless parameter. This is the intercept correction value. This is the slope correction value. The way the subscripts i and j are defined is the same as They are the same and are dimensionless parameters;

[0021] b) Based on the strain at each position of the hollow traction pin (1) calculated. Calculate the component forces at each position of the hollow traction pin. The calculation formula is as follows:

[0022]

[0023] In the formula, the calculated component force at each position of the hollow traction pin is... The subscript i is 1, which means the calculated force is longitudinal, and 2 means the calculated force is transverse. j is 1, which means the calculated force is solved by the first-stage strain gauge group in the longitudinal or transverse direction, and j is 2, which means the calculated force is solved by the second-stage strain gauge group in the longitudinal or transverse direction. The elastic modulus of the selected material;

[0024] c) Calculate the component forces at each position of the hollow traction pin based on the calculated results. and confidence coefficient The total longitudinal force on the hollow traction pin was calculated using a weighted average. and lateral force The calculation formula is as follows:

[0025]

[0026] d) The data calculation module sends out the calculated longitudinal force. and lateral force .

[0027] The machining accuracy coefficient of the square blind hole The calculation formula is:

[0028]

[0029] In the formula, This represents the actual roughness of the wall of a square blind hole, in micrometers. As the reference roughness, take micrometer; The angle between the direction of the hole wall machining texture and the rotation axis of the hollow traction pin is measured in radians. The Vickers hardness value after the hole wall is machined; This represents the original Vickers hardness value of the material.

[0030] The uniformity coefficient of the hollow traction pin material The calculation formula is:

[0031]

[0032] In the formula, Let be the equivalent diameter of the i-th defect in the hollow traction pin material. The equivalent diameter refers to the diameter of the corresponding sphere when the defect is converted into a sphere of equal volume, and the unit is millimeters. The number of defects per unit volume; The total volume of the defective area in the material is expressed in cubic millimeters. This represents the maximum carbon concentration in the section where the hollow traction pin meets the saddle. This represents the minimum carbon concentration in the region. The nominal average carbon concentration in this region is obtained by looking up the material grade in a table. Expressed as a mass fraction, it represents the weight of carbon in grams per 100 grams of material; This refers to the maximum grain diameter of the section where the hollow traction pin meets the saddle. The minimum grain diameter is the section where the hollow traction pin mates with the saddle. The average grain diameter is the section where the hollow traction pin mates with the saddle. All units are in micrometers;

[0033] The fatigue coefficient of the hollow traction pin material The calculation formula is:

[0034]

[0035] In the formula, This represents the total number of stress cycles within the design life. This refers to the stress amplitude in actual work, in megapascals (MPA). The symmetrical cyclic fatigue limit of the material is expressed in megapascals (MPa).

[0036] Constructing the quality requirement coefficient of the traction pin The calculation formula is:

[0037]

[0038] In the formula, For the weight of the semi-trailer; Design load mass; The baseline semi-trailer weight is 3 tons; The baseline load mass is taken as 10 tons; Designed for usage time; For the baseline usage period, we take 15 years; For design working condition strength coefficient; These are positive coefficients, and are taken as 0.3, 0.2, and 1.1 respectively.

[0039] The ramp frequency factor in the formula for calculating the strength coefficient of the design working condition The calculation formula is:

[0040]

[0041] The bump intensity factor in the formula for calculating the design working condition intensity coefficient The calculation formula is:

[0042]

[0043] in, The frequency of the ramp is expressed as times per hundred kilometers. The frequency reference value for the ramp is 5 times per 100 kilometers; The maximum slope is expressed as a percentage. The baseline slope value is 5%. The standard deviation of the slope is expressed as a percentage. The frequency of bumps is measured in times per minute. The baseline value for the frequency of turbulence is 10 times per minute; Maximum turbulence acceleration, in meters per second squared; The baseline value for turbulence acceleration is taken as 2 meters per second squared. The average duration of a single jolt, in seconds; The baseline value for the average duration of a single turbulence is 0.5 seconds; the index =1.2, =1.5, =1.3, =1.4; The ramp frequency reference value Slope reference value Bump frequency reference value Bump acceleration reference value The baseline value for the average duration of a single turbulence. This data was obtained from data collected and analyzed by the test vehicle under representative working conditions.

[0044] The limit of the traction pin strength weakening factor Based on the quality requirement coefficient of the traction pin The calculation is as follows:

[0045]

[0046] in This is a conservative coefficient; the larger the conservative coefficient, the lower the limit of the traction pin strength weakening factor. The smaller the value, the higher the strength requirement for the intelligent traction pin; the specific value is determined through experiments.

[0047] The selected rectangular blind hole has a cross-sectional side length of... Corresponding traction pin strength reduction factor Not greater than ;choose The upper limit is 0.9 to 1 times the cross-sectional side length of the cuboid blind hole.

[0048] The longitudinal strain gauge groups (311, 312) are installed in front of and behind the strain gauge bracket, and the transverse strain gauge groups (321, 322) are installed to the left and right of the strain gauge bracket; strain gauges installed at the same height and position on the strain gauge bracket are placed side by side in the transverse direction; for the longitudinal strain gauge groups, facing the front of the strain gauge bracket (2), those installed on the left are called the left position, and those installed on the right are called the right position; for the transverse strain gauge groups, facing the left side of the strain gauge bracket (2), those installed on the left are called the left position, and those installed on the right are called the right position; the distance from the plane formed by the installation positions of each secondary strain gauge group to the installation end of the hollow traction pin (1) is... The selection of strain gauges should ensure that the strain gauges are completely within the traction pin shaft section coupled to the saddle of the hollow traction pin, and meet the following requirements: , ;

[0049] The differential bridge is according to Figure 4 The circuit is connected in the following manner: for each secondary strain gauge group (311, 312) of the longitudinal strain gauge group, the strain gauge (3111, 3121) installed on the left front of the strain gauge bracket (2) is installed at position A of the differential bridge; the strain gauge (3112, 3122) installed on the right front of the strain gauge bracket (2) is installed at position D of the differential bridge; the strain gauge (3114, 3124) installed on the left rear of the strain gauge bracket (2) is installed at position B of the differential bridge; and the strain gauge (3112, 3122) installed on the right rear of the strain gauge bracket (2) is installed at position D of the differential bridge. Position C; For each secondary strain gauge group (321, 322) of the transverse strain gauge group, the strain gauge (3211, 3221) installed on the left side of the strain gauge bracket (2) is installed at position A of the differential bridge; the strain gauge (3212, 3222) installed on the right side of the strain gauge bracket (2) is installed at position D of the differential bridge; the strain gauge (3224, 3214) installed on the left side of the right side of the strain gauge bracket (2) is installed at position B of the differential bridge; and the strain gauge (3213, 3223) installed on the right side of the right side of the strain gauge bracket (2) is installed at position C of the differential bridge.

[0050] After the strain gauge bracket (2) with strain gauge assembly (3) and anti-vibration foam (4) is installed into the hollow traction pin (1), the resistance value of each strain gauge is recorded again and counted as... The unit is ohms. Subscript i = 1 represents a longitudinal strain gauge group, and subscript i = 2 represents a transverse strain gauge group; subscript j = 1 represents a first-stage strain gauge group, and subscript j = 2 represents a second-stage strain gauge group; subscript k represents the strain gauge number, which can be 1, 2, 3, or 4. The resistance subscript of the strain gauge is the same as the last three digits of the strain gauge part number; the resistance of each strain gauge in the strain gauge group before installation is... .

[0051] The inner ring of the vibration-damping foam has a Shore hardness of [missing value]. The free radius is The unit is millimeters, and the Shore hardness of the outer ring foam is [value missing]. The free outer radius is The unit is millimeters;

[0052] The formula for calculating the free radius of the inner circle of the foam is as follows:

[0053]

[0054] in This is the baseline value for the free radius of the inner circle, in millimeters, calibrated experimentally. The inner radius is the operating response coefficient, 0 < <0.5;

[0055] The formula for calculating the free radius of the outer ring of the anti-vibration foam is as follows:

[0056]

[0057] in This is the baseline value for the outer free radius, in millimeters, calibrated experimentally. The outer radius is the operating response coefficient, 0.8 < <1.5;

[0058] The formula for calculating the Shore hardness of the inner ring is as follows:

[0059]

[0060] in The basic hardness of the inner ring foam is 20 < <40; The inner ring hardness response coefficient is 0.3 < <0.8;

[0061] The formula for calculating the Shore hardness of the outer ring is as follows:

[0062]

[0063] in The basic hardness of the outer ring foam is 40 < <60; The outer ring hardness response coefficient is 1.0 < <2.0;

[0064] The above parameters Calibration was achieved through experiments.

[0065] The data processing module (5) pre-writes the resistance value of the strain gauge before installation. And the resistance of each strain gauge after installing the strain gauge bracket (2) with strain gauge assembly (3) and vibration damping foam (4) into the hollow traction pin (1). The intercept correction value Calculation formula:

[0066] In the formula The intercept correction coefficients are determined experimentally; the subscripts i and j are defined in the same way as... same;

[0067] The slope correction value Calculation formula:

[0068]

[0069] In the formula The slope correction coefficients are determined experimentally; the subscripts i and j are defined in the same way as... same;

[0070] The confidence coefficient The calculation formula is:

[0071]

[0072] In the formula, The historical average consistency coefficient. For temperature coefficient, coefficient The way the subscripts i and j are defined is the same as same; Strain at various positions of the hollow traction pin The standard deviation, the way the subscripts i and j are defined is the same as same;

[0073] The formula for calculating the historical average consistency coefficient is as follows:

[0074]

[0075] In the formula, For historical strain values, the subscripts i, j, k have the same meaning as the variables. Similarly, the subscript m represents the strain as the data from the m-th historical record; The average of historical strain values;

[0076] The temperature coefficient The calculation formula is:

[0077]

[0078] In the formula This indicates the internal temperature of the hollow traction pin (1), in degrees Celsius. To calibrate the temperature, subscripts i, j and Subscripts have the same meaning; This refers to the longitudinal temperature influence coefficient, where i=1 represents the lateral temperature influence coefficient, and i=2 represents the lateral temperature influence coefficient. The results were determined experimentally.

[0079] The beneficial effects of this invention are:

[0080] The hollow traction pin in this invention has a hole coaxial with its own rotation center to accommodate the element for measuring the articulation force. A strain gauge bracket acts as a bridge between the hollow traction pin and the strain gauge assembly. The strain gauge bracket is installed inside the hollow traction pin and deforms along with it. The strain gauge assembly is attached to the strain gauge bracket and forms a differential bridge to sense the deformation of the hollow traction pin in real time. The data calculation module calculates the voltage value output by the differential bridge and sends the calculated articulation force externally. This invention can calculate the current articulation force on the traction pin based on its real-time deformation, providing data preparation for intelligent algorithms such as semi-trailer stability control and quality identification. Attached Figure Description

[0081] The invention will now be further described with reference to the accompanying drawings:

[0082] Figure 1 This is an overall axonometric drawing of an intelligent traction pin for connecting a tractor and a semi-trailer, as described in this invention.

[0083] Figure 2 This is a cross-sectional view of an intelligent traction pin for connecting a tractor and a semi-trailer, as described in this invention.

[0084] Figure 3 This invention relates to a strain gauge bracket and vibration damping foam assembly for an intelligent traction pin used in tractor-trailer connections;

[0085] Figure 4 This is a strain gauge group layout diagram of an intelligent traction pin for connecting a tractor and a semi-trailer, as described in this invention.

[0086] Figure 5 This is a reference diagram showing the attachment position of the differential bridge of the intelligent traction pin for connecting a tractor and a semi-trailer, as described in this invention. Detailed Implementation

[0087] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0088] refer to Figure 1 , Figure 2 The present invention describes an intelligent traction pin for connecting a tractor and a semi-trailer, comprising a hollow traction pin (1), a strain gauge bracket (2), a strain gauge assembly (3), vibration damping foam (4), and a data processing module (5). The installation method of the above components is as follows: Figure 2 As shown, to clearly demonstrate the internal structure, Figure 2 The anti-vibration foam (4) is not shown in the cross-sectional view;

[0089] The hollow traction pin (1) has the same external dimensions as the standard 90 traction pin and has a square blind hole with a side length of and its centroid is coaxial with the traction pin. The end of the blind hole extends 5 mm into the end cylinder of the traction pin. The mounting end of the hollow traction pin (1) has a threaded hole, which is coaxial with the square blind hole. The mounting end of the hollow traction pin (1) refers to the end face used to fix it to the semi-trailer. The square blind hole is connected to the threaded hole. The threaded hole is located at the end of the hollow traction pin (1) and forms a seal with the end cap (6).

[0090] The strain gauge bracket (2) is installed on the inner wall of the hollow traction pin (1), and the strain gauge assembly (3) is attached to the strain gauge bracket (2). After the strain gauge assembly (3) is attached, the strain gauge bracket (2) is filled with anti-vibration foam (4) to provide protection and support; the data calculation module (5) is connected to the strain gauge assembly (3) and is used to calculate the measurement signal.

[0091] The side length of the blind hole cross section The following condition must be met: the strength reduction factor of the traction pin corresponding to the blind hole. Less than the threshold of the traction pin strength weakening factor The traction pin strength weakening factor The calculation formula is:

[0092]

[0093] In the formula and The diameter and length of the section where the traction pin mates with the saddle are measured in millimeters. Poisson's ratio for hollow traction pin material; The machining accuracy coefficient for a square blind hole; The uniformity coefficient of the hollow traction pin material; The fatigue coefficient of the hollow traction pin material;

[0094] The threshold of the traction pin strength weakening factor This is a critical value set to ensure that the traction pin meets the predetermined safety strength.

[0095] Reference Figure 2 , Figure 3 The strain gauge bracket (2) is a rectangular thin-walled structure, consisting of upper and lower bottom surfaces with a thickness greater than the side surface and partially hollowed-out side surfaces; the upper and lower bottom surfaces of the strain gauge bracket (2) form a transition fit with the blind hole of the hollow traction pin (1), if the design working condition strength coefficient The transition fit used is H7 / m6; otherwise, the transition fit used is H7 / n6. The threshold value for the working condition strength coefficient was determined to be 0.58 through experiments; the formula for calculating the design working condition strength coefficient is as follows:

[0096]

[0097] In the formula, These are the ramp frequency factor and the bump intensity factor, respectively. The weighting factors for the slope frequency factor and the bump intensity factor are 0.38 and 0.62, respectively. As a positive exponent, we take 0.7;

[0098] The strain gauge bracket (2) has a thickness of 5 mm on both the top and bottom surfaces. The blind hole mating positions with the hollow traction pin are located on the shaft sections on both sides of the mating position between the hollow traction pin and the saddle. When installing the strain gauge bracket, the hollow traction pin must be heated. There is a directional mark on the outer side of the bottom surface of the strain gauge bracket near a certain edge, indicating the front of the strain gauge bracket. Facing the bottom surface of the strain gauge bracket (2), determine the left, right and rear of the strain gauge bracket based on the front of the strain gauge bracket. When installing, the front of the strain gauge bracket should coincide with the direction of travel of the semi-trailer.

[0099] Reference Figure 4The strain gauge group (3) is divided into a longitudinal strain gauge group (311, 312) and a transverse strain gauge group (321, 322), which are installed on the strain gauge bracket (2). The longitudinal strain gauge group (311, 312) consists of a longitudinal first-stage strain gauge group (311) and a longitudinal second-stage strain gauge group (312), and the transverse strain gauge group (321, 322) consists of a transverse first-stage strain gauge group (321) and a transverse second-stage strain gauge group (322). Each secondary strain gauge group consists of four strain gauges. The four strain gauges of each strain gauge group form a differential bridge. The four strain gauges of each secondary strain gauge group are installed on a plane perpendicular to the axis of the hollow traction pin (1), and the distance between the plane and the installation end of the hollow traction pin (1) is [missing information]. The unit is millimeters; The subscript i is 1, representing the longitudinal strain gauge group; the subscript i is 2, representing the transverse strain gauge group; the subscript j is 1, representing the first-stage strain gauge group; the subscript j is 2, representing the second-stage strain gauge group.

[0100] Reference Figure 3 The vibration damping foam (4) is a cylindrical sponge, which is composed of two layers of different materials arranged concentrically and is filled inside the strain gauge bracket (2);

[0101] Reference Figure 2 The data calculation module is installed in the end cap (6) and consists of a micro-microcontroller connected to the four differential bridges. It calculates the force on the intelligent traction pin based on the output voltage value of the differential bridges. The calculation process includes:

[0102] a) Calculate the strain at each position of the hollow traction pin based on the strain gauge output voltage value. The calculation formula is as follows:

[0103]

[0104] In the formula, This is the input voltage of the differential bridge, in volts. This is the output voltage of the bridge circuit, in volts. For strain at various positions of the hollow traction pin, the definition method of the subscripts is the same as... same; The nominal sensitivity of the strain gauge is a dimensionless parameter. This is the intercept correction value. This is the slope correction value. The way the subscripts i and j are defined is the same as They are the same and are dimensionless parameters;

[0105] b) Based on the strain at each position of the hollow traction pin (1) calculated. Calculate the component forces at each position of the hollow traction pin. The calculation formula is as follows:

[0106]

[0107] In the formula, the calculated component force at each position of the hollow traction pin is... The subscript i is 1, which means the calculated force is longitudinal, and 2 means the calculated force is transverse. j is 1, which means the calculated force is solved by the first-stage strain gauge group in the longitudinal or transverse direction, and j is 2, which means the calculated force is solved by the second-stage strain gauge group in the longitudinal or transverse direction. The elastic modulus of the selected material;

[0108] c) Calculate the component forces at each position of the hollow traction pin based on the calculated results. and confidence coefficient The total longitudinal force on the hollow traction pin was calculated using a weighted average. and lateral force The calculation formula is as follows:

[0109]

[0110] d) The data calculation module sends out the calculated longitudinal force. and lateral force .

[0111] Machining accuracy coefficient of square blind holes The calculation formula is:

[0112]

[0113] In the formula, This represents the actual roughness of the wall of a square blind hole, in micrometers. As the reference roughness, take micrometer; The angle between the direction of the hole wall machining texture and the rotation axis of the hollow traction pin is measured in radians. The Vickers hardness value after the hole wall is machined; This represents the original Vickers hardness value of the material.

[0114] Hollow traction pin material uniformity coefficient The calculation formula is:

[0115]

[0116] In the formula, Let be the equivalent diameter of the i-th defect in the hollow traction pin material. The equivalent diameter refers to the diameter of the corresponding sphere when the defect is converted into a sphere of equal volume, and the unit is millimeters. The number of defects per unit volume; The total volume of the defective area in the material is expressed in cubic millimeters. This represents the maximum carbon concentration in the section where the hollow traction pin meets the saddle. This represents the minimum carbon concentration in the region. The nominal average carbon concentration in this region is obtained by looking up the material grade in a table. Expressed as a mass fraction, it represents the weight of carbon in grams per 100 grams of material; This refers to the maximum grain diameter of the section where the hollow traction pin meets the saddle. The minimum grain diameter is the section where the hollow traction pin mates with the saddle. The average grain diameter is the section where the hollow traction pin mates with the saddle. All units are in micrometers;

[0117] Fatigue coefficient of hollow traction pin material The calculation formula is:

[0118]

[0119] In the formula, This represents the total number of stress cycles within the design life. This refers to the stress amplitude in actual work, in megapascals (MPA). The symmetrical cyclic fatigue limit of the material is expressed in megapascals (MPa).

[0120] Constructing the quality requirement coefficient of the traction pin The calculation formula is:

[0121]

[0122] In the formula, For the weight of the semi-trailer; Design load mass; The baseline semi-trailer weight is 3 tons; The baseline load mass is taken as 10 tons; Designed for usage time; For the baseline usage period, we take 15 years; For design working condition strength coefficient; These are positive coefficients, and are taken as 0.3, 0.2, and 1.1 respectively.

[0123] The ramp frequency factor in the formula for calculating the strength coefficient of the design working condition. The calculation formula is:

[0124]

[0125] Bump intensity factor in the formula for calculating the intensity coefficient of design working conditions The calculation formula is:

[0126]

[0127] in, The frequency of the ramp is expressed as times per hundred kilometers. The frequency reference value for the ramp is 5 times per 100 kilometers; The maximum slope is expressed as a percentage. The baseline slope value is 5%. The standard deviation of the slope is expressed as a percentage. The frequency of bumps is measured in times per minute. The baseline value for the frequency of turbulence is 10 times per minute; Maximum turbulence acceleration, in meters per second squared; The baseline value for turbulence acceleration is taken as 2 meters per second squared. The average duration of a single jolt, in seconds; The baseline value for the average duration of a single turbulence is 0.5 seconds; the index =1.2, =1.5, =1.3, =1.4; The ramp frequency reference value Slope reference value Bump frequency reference value Bump acceleration reference value The baseline value for the average duration of a single turbulence. This data was obtained from data collected and analyzed by the test vehicle under representative working conditions.

[0128] Traction pin strength weakening factor limit Based on the quality requirement coefficient of the traction pin The calculation is as follows:

[0129]

[0130] in This is a conservative coefficient; the larger the conservative coefficient, the lower the limit of the traction pin strength weakening factor. The smaller the value, the higher the strength requirement for the intelligent traction pin; the specific value is determined through experiments.

[0131] The selected rectangular blind hole has a cross-sectional side length of... Corresponding traction pin strength reduction factor Not greater than ;choose The upper limit is 0.9 to 1 times the cross-sectional side length of the cuboid blind hole.

[0132] Reference Figure 4The longitudinal strain gauge groups (311, 312) are installed in front of and behind the strain gauge bracket, and the transverse strain gauge groups (321, 322) are installed on the left and right sides of the strain gauge bracket; strain gauges installed at the same height and position on the strain gauge bracket are placed side by side in the transverse direction; for the longitudinal strain gauge group, facing the front of the strain gauge bracket (2), the one installed on the left is called the left position, and the one installed on the right is called the right position; for the transverse strain gauge group, facing the left side of the strain gauge bracket (2), the one installed on the left is called the left position, and the one installed on the right is called the right position; the distance from the plane formed by the installation positions of each secondary strain gauge group to the installation end of the hollow traction pin (1) is... The selection of strain gauges should ensure that the strain gauges are completely within the traction pin shaft section coupled to the saddle of the hollow traction pin, and meet the following requirements: , ;

[0133] Reference Figure 4 , Figure 5 Each secondary strain gauge group (311, 312) of the longitudinal strain gauge group is installed at position A of the differential bridge where the strain gauge (3111, 3121) is located in front of the strain gauge bracket (2) on the left; at position D of the differential bridge where the strain gauge (3112, 3122) is located in front of the strain gauge bracket (2) on the right; at position B of the differential bridge where the strain gauge (3114, 3124) is located in rear of the strain gauge bracket (2) on the left; and at position C of the differential bridge where the strain gauge (3112, 3122) is located in rear of the strain gauge bracket (2). For each secondary strain gauge group (321, 322) of the transverse strain gauge group, the strain gauge (3211, 3221) installed on the left side of the strain gauge bracket (2) is installed at position A of the differential bridge; the strain gauge (3212, 3222) installed on the right side of the strain gauge bracket (2) is installed at position D of the differential bridge; the strain gauge (3224, 3214) installed on the right side of the strain gauge bracket (2) is installed at position B of the differential bridge; and the strain gauge (3213, 3223) installed on the right side of the strain gauge bracket (2) is installed at position C of the differential bridge.

[0134] After the strain gauge bracket (2) with strain gauge assembly (3) and anti-vibration foam (4) is installed into the hollow traction pin (1), the resistance value of each strain gauge is recorded again and counted as... The unit is ohms. Subscript i = 1 represents a longitudinal strain gauge group, and subscript i = 2 represents a transverse strain gauge group; subscript j = 1 represents a first-stage strain gauge group, and subscript j = 2 represents a second-stage strain gauge group; subscript k represents the strain gauge number, which can be 1, 2, 3, or 4. The resistance subscript of the strain gauge is the same as the last three digits of the strain gauge part number; the resistance of each strain gauge in the strain gauge group before installation is... .

[0135] The inner ring of the vibration-damping foam has a Shore hardness of [missing value]. The free radius is The unit is millimeters, and the Shore hardness of the outer ring foam is [value missing]. The free outer radius is The unit is millimeters;

[0136] The formula for calculating the free radius of the inner circle of the foam is as follows:

[0137]

[0138] in This is the baseline value for the free radius of the inner circle, in millimeters, calibrated experimentally. The inner radius is the operating response coefficient, 0 < <0.5;

[0139] The formula for calculating the free radius of the outer ring of the anti-vibration foam is as follows:

[0140]

[0141] in This is the baseline value for the outer free radius, in millimeters, calibrated experimentally. The outer radius is the operating response coefficient, 0.8 < <1.5;

[0142] The formula for calculating the Shore hardness of the inner ring is as follows:

[0143]

[0144] in The basic hardness of the inner ring foam is 20 < <40; The inner ring hardness response coefficient is 0.3 < <0.8;

[0145] The formula for calculating the Shore hardness of the outer ring is as follows:

[0146]

[0147] in The basic hardness of the outer ring foam is 40 < <60; The outer ring hardness response coefficient is 1.0 < <2.0;

[0148] The above parameters Calibration was achieved through experiments.

[0149] The data processing module pre-writes the resistance value of the strain gauge before installation. And the resistance of each strain gauge after installing the strain gauge bracket (2) with strain gauge assembly (3) and vibration damping foam (4) into the hollow traction pin (1). The intercept correction value Calculation formula:

[0150] In the formula The intercept correction coefficients are determined experimentally; the subscripts i and j are defined in the same way as... same;

[0151] The slope correction value Calculation formula:

[0152]

[0153] In the formula The slope correction coefficients are determined experimentally; the subscripts i and j are defined in the same way as... same;

[0154] The confidence coefficient The calculation formula is:

[0155]

[0156] In the formula, The historical average consistency coefficient. For temperature coefficient, coefficient The way the subscripts i and j are defined is the same as same; Strain at various positions of the hollow traction pin The standard deviation, the way the subscripts i and j are defined is the same as same;

[0157] The formula for calculating the historical average consistency coefficient is as follows:

[0158]

[0159] In the formula, For historical strain values, the subscripts i, j, k have the same meaning as the variables. Similarly, the subscript m represents the strain as the data from the m-th historical record; The average of historical strain values;

[0160] The temperature coefficient The calculation formula is:

[0161]

[0162] In the formula This indicates the internal temperature of the hollow traction pin (1), in degrees Celsius. To calibrate the temperature, subscripts i, j and Subscripts have the same meaning; This refers to the longitudinal temperature influence coefficient, where i=1 represents the lateral temperature influence coefficient, and i=2 represents the lateral temperature influence coefficient. The results were determined experimentally.

Claims

1. An intelligent towing pin for connecting a tractor and a semi-trailer, characterized in that, The intelligent traction pin is used to obtain the articulation force of the tractor and semi-trailer. It consists of a hollow traction pin (1), a strain gauge bracket (2), a strain gauge group (3), anti-vibration foam (4), and a data calculation module (5). The hollow traction pin (1) has the same external dimensions as the standard 90 traction pin and has a square blind hole with a side length of [missing information]. The centroid is coaxial with the traction pin; the end of the blind hole extends 5 mm into the end cylinder of the traction pin; the mounting end of the hollow traction pin (1) has a threaded hole, which is coaxial with the aforementioned square blind hole; the mounting end of the hollow traction pin (1) refers to the end face used for fixing to the semi-trailer; the aforementioned square blind hole is connected to the threaded hole; the threaded hole is located at the end of the hollow traction pin (1) and forms a seal with the end cap (6); the side length of the blind hole cross section is... The following condition must be met: the strength reduction factor of the traction pin corresponding to the blind hole. Less than the threshold of the traction pin strength weakening factor The traction pin strength weakening factor The calculation formula is: In the formula and The diameter and length of the section where the traction pin mates with the saddle are measured in millimeters. Poisson's ratio for hollow traction pin material; The machining accuracy coefficient for a square blind hole; The uniformity coefficient of the hollow traction pin material; The fatigue coefficient of the hollow traction pin material; The threshold of the traction pin strength weakening factor This is a critical value set to ensure that the traction pin meets the predetermined safety strength. The strain gauge bracket (2) is a rectangular thin-walled structure, consisting of upper and lower bottom surfaces with a thickness greater than the side surfaces and partially hollowed-out side surfaces; the upper and lower bottom surfaces of the strain gauge bracket (2) form a transition fit with the blind hole of the hollow traction pin (1), if the design working condition strength coefficient The transition fit used is H7 / m6; otherwise, the transition fit used is H7 / n6. The threshold value for the working condition strength coefficient is used; the formula for calculating the design working condition strength coefficient is as follows: In the formula, These are the ramp frequency factor and the bump intensity factor, respectively. These are the weighting factors for the slope frequency factor and the bump intensity factor; It is a positive exponent; The strain gauge bracket (2) has a thickness of 5 mm on both the top and bottom surfaces. The blind hole mating positions with the hollow traction pin are located on the shaft sections on both sides of the mating position between the hollow traction pin and the saddle. When installing the strain gauge bracket, the hollow traction pin must be heated. There is a directional mark on the outer side of the bottom surface of the strain gauge bracket near a certain edge, indicating the front of the strain gauge bracket. Facing the bottom surface of the strain gauge bracket (2), the left, right and rear of the strain gauge bracket are determined according to the front of the strain gauge bracket. When installing, the front of the strain gauge bracket is in the same direction as the semi-trailer. The strain gauge group (3) is divided into a longitudinal strain gauge group (311, 312) and a transverse strain gauge group (321, 322), which are installed on the strain gauge bracket (2). The longitudinal strain gauge group (311, 312) consists of a longitudinal primary strain gauge group (311) and a longitudinal secondary strain gauge group (312), and the transverse strain gauge group (321, 322) consists of a transverse primary strain gauge group (321) and a transverse secondary strain gauge group (322). Each secondary strain gauge group consists of four strain gauges. The four strain gauges of each strain gauge group form a differential bridge. The four strain gauges of each secondary strain gauge group are installed on a plane perpendicular to the axis of the hollow traction pin (1), and the distance between the plane and the installation end of the hollow traction pin (1) is [missing information]. The unit is millimeters; The subscript i is 1, representing the longitudinal strain gauge group; the subscript i is 2, representing the transverse strain gauge group; the subscript j is 1, representing the first-stage strain gauge group; the subscript j is 2, representing the second-stage strain gauge group. The vibration damping foam (4) is a cylindrical sponge, which is composed of two layers of different materials arranged concentrically and is filled inside the strain gauge bracket (2); The data calculation module (5) consists of a micro microcontroller connected to the four differential bridges, and calculates the force on the intelligent traction pin based on the output voltage value of the differential bridges. The solution process includes: a) Calculate the strain at each position of the hollow traction pin based on the strain gauge output voltage value. The calculation formula is as follows: In the formula, This is the input voltage of the differential bridge, in volts. This is the output voltage of the bridge circuit, in volts. For strain at various positions of the hollow traction pin, the definition method of the subscripts is the same as... same; The nominal sensitivity of the strain gauge is a dimensionless parameter. This is the intercept correction value. This is the slope correction value. The way the subscripts i and j are defined is the same as They are the same and are dimensionless parameters; b) Based on the strain at each position of the hollow traction pin (1) calculated. Calculate the component forces at each position of the hollow traction pin. The calculation formula is as follows: In the formula, the calculated component force at each position of the hollow traction pin is... The subscript i is 1, which means the calculated force is longitudinal, and 2 means the calculated force is transverse. j is 1, which means the calculated force is solved by the first-stage strain gauge group in the longitudinal or transverse direction, and j is 2, which means the calculated force is solved by the second-stage strain gauge group in the longitudinal or transverse direction. The elastic modulus of the selected material; c) Calculate the component forces at each position of the hollow traction pin based on the calculated results. and confidence coefficient The total longitudinal force on the hollow traction pin was calculated using a weighted average. and lateral force The calculation formula is as follows: d) The data calculation module sends out the calculated longitudinal force. and lateral force .

2. The intelligent towing pin for connecting a tractor and a semi-trailer according to claim 1, characterized in that, The machining accuracy coefficient of the square blind hole The calculation formula is: In the formula, This represents the actual roughness of the wall of a square blind hole, in micrometers. As the reference roughness; The angle between the direction of the hole wall machining texture and the rotation axis of the hollow traction pin is measured in radians. The Vickers hardness value after the hole wall is machined; This represents the original Vickers hardness value of the material. The uniformity coefficient of the hollow traction pin material The calculation formula is: In the formula, Let be the equivalent diameter of the i-th defect in the hollow traction pin material. The equivalent diameter refers to the diameter of the corresponding sphere when the defect is converted into a sphere of equal volume, and the unit is millimeters. The number of defects per unit volume; The total volume of the defective area in the material is expressed in cubic millimeters. This represents the maximum carbon concentration in the section where the hollow traction pin meets the saddle. This represents the minimum carbon concentration in the region. The nominal average carbon concentration in this region is obtained by looking up the material grade in a table. Expressed as a mass fraction, it represents the weight of carbon in grams per 100 grams of material; This refers to the maximum grain diameter of the section where the hollow traction pin meets the saddle. The minimum grain diameter is the section where the hollow traction pin mates with the saddle. The average grain diameter is the section where the hollow traction pin mates with the saddle. All units are in micrometers; The fatigue coefficient of the hollow traction pin material The calculation formula is: In the formula, This represents the total number of stress cycles within the design life. This refers to the stress amplitude in actual work, in megapascals (MPA). The symmetrical cyclic fatigue limit of the material is expressed in megapascals (MPa). Constructing the quality requirement coefficient of the traction pin The calculation formula is: In the formula, For the weight of the semi-trailer; Design load mass; Based on the standard semi-trailer weight; The reference load mass; Designed for usage time; Based on the usage time; For design working condition strength coefficient; It is a positive coefficient; The ramp frequency factor in the formula for calculating the strength coefficient of the design working condition The calculation formula is: The bump intensity factor in the formula for calculating the design working condition intensity coefficient The calculation formula is: in, The frequency of the ramp is expressed as times per hundred kilometers. This is the reference value for ramp frequency; The maximum slope is expressed as a percentage. This is the baseline value for slope. The standard deviation of the slope is expressed as a percentage. This refers to the frequency of turbulence. This serves as a reference value for the frequency of turbulence. Maximum turbulence acceleration, in meters per second squared; This is the baseline value for bump acceleration; The average duration of a single jolt, in seconds; The average duration of a single turbulence event is the baseline; index =1.2, =1.5, =1.3, =1.4; The ramp frequency reference value Slope reference value Bump frequency reference value Bump acceleration reference value The baseline value for the average duration of a single turbulence. This data was obtained from data collected and analyzed by the test vehicle under representative working conditions. The limit of the traction pin strength weakening factor Based on the quality requirement coefficient of the traction pin The calculation is as follows: in This is a conservative coefficient; the larger the conservative coefficient, the lower the limit of the traction pin strength weakening factor. The smaller the value, the higher the strength requirement for the intelligent traction pin; the specific value is determined through experiments. The selected rectangular blind hole has a cross-sectional side length of... Corresponding traction pin strength reduction factor Not greater than ;choose The upper limit is 0.9 to 1 times the cross-sectional side length of the cuboid blind hole.

3. The intelligent towing pin for connecting a tractor and a semi-trailer according to claim 1, characterized in that, The longitudinal strain gauge groups (311, 312) are installed in front of and behind the strain gauge bracket, and the transverse strain gauge groups (321, 322) are installed to the left and right of the strain gauge bracket; strain gauges installed at the same height and position on the strain gauge bracket are placed side by side in the transverse direction; for the longitudinal strain gauge groups, facing the front of the strain gauge bracket (2), those installed on the left are called the left position, and those installed on the right are called the right position; for the transverse strain gauge groups, facing the left side of the strain gauge bracket (2), those installed on the left are called the left position, and those installed on the right are called the right position; the distance from the plane formed by the installation positions of each secondary strain gauge group to the installation end of the hollow traction pin (1) is... The selection of strain gauges should ensure that the strain gauges are completely within the traction pin shaft section coupled to the saddle of the hollow traction pin, and meet the following requirements: , ; The differential bridge is connected in the manner shown in Figure 4. For each secondary strain gauge group (311, 312) of the longitudinal strain gauge group, the strain gauge (3111, 3121) installed on the left front of the strain gauge bracket (2) is installed at position A of the differential bridge; the strain gauge (3112, 3122) installed on the right front of the strain gauge bracket (2) is installed at position D of the differential bridge; the strain gauge (3114, 3124) installed on the left rear of the strain gauge bracket (2) is installed at position B of the differential bridge; and the strain gauge (3112, 3122) installed on the right rear of the strain gauge bracket (2) is installed at position D of the differential bridge. The position of the differential bridge is C; for each secondary strain gauge group (321, 322) of the transverse strain gauge group, the strain gauge (3211, 3221) installed on the left side of the strain gauge bracket (2) is installed at position A of the differential bridge; the strain gauge (3212, 3222) installed on the right side of the strain gauge bracket (2) is installed at position D of the differential bridge; the strain gauge (3224, 3214) installed on the left side of the strain gauge bracket (2) is installed at position B of the differential bridge; and the strain gauge (3213, 3223) installed on the right side of the strain gauge bracket (2) is installed at position C of the differential bridge. After the strain gauge bracket (2) with strain gauge assembly (3) and anti-vibration foam (4) is installed into the hollow traction pin (1), the resistance value of each strain gauge is recorded again and counted as... The unit is ohms. Subscript i = 1 represents a longitudinal strain gauge group, and subscript i = 2 represents a transverse strain gauge group; subscript j = 1 represents a first-stage strain gauge group, and subscript j = 2 represents a second-stage strain gauge group; subscript k represents the strain gauge number, which can be 1, 2, 3, or 4. The resistance subscript of the strain gauge is the same as the last three digits of the strain gauge part number; the resistance of each strain gauge in the strain gauge group before installation is... .

4. The intelligent towing pin for connecting a tractor and a semi-trailer according to claim 1, characterized in that, The inner ring of the vibration-damping foam has a Shore hardness of [missing value]. The free radius is The unit is millimeters, and the Shore hardness of the outer ring foam is [value missing]. The free outer radius is The unit is millimeters; The formula for calculating the free radius of the inner circle of the foam is as follows: in This is the baseline value for the free radius of the inner circle, in millimeters, calibrated experimentally. The inner radius is the operating response coefficient, 0 < <0.5; The formula for calculating the free radius of the outer ring of the anti-vibration foam is as follows: in This is the baseline value for the outer free radius, in millimeters, calibrated experimentally. The outer radius is the operating response coefficient, 0.8 < <1.5; The formula for calculating the Shore hardness of the inner ring is as follows: in The basic hardness of the inner ring foam is 20 < <40; The inner ring hardness response coefficient is 0.3 < <0.8; The formula for calculating the Shore hardness of the outer ring is as follows: in The basic hardness of the outer ring foam is 40 < <60; The outer ring hardness response coefficient is 1.0 < <2.0; The above parameters Calibration was achieved through experiments.

5. The intelligent towing pin for connecting a tractor and a semi-trailer according to claim 1, characterized in that, The data processing module (5) pre-writes the resistance value of the strain gauge before installation. And the resistance of each strain gauge after installing the strain gauge bracket (2) with strain gauge assembly (3) and vibration damping foam (4) into the hollow traction pin (1). The intercept correction value Calculation formula: In the formula The intercept correction coefficients are determined experimentally; the subscripts i and j are defined in the same way as... same; The slope correction value Calculation formula: In the formula The slope correction coefficients are determined experimentally; the subscripts i and j are defined in the same way as... same; The confidence coefficient The calculation formula is: In the formula, The historical average consistency coefficient. For temperature coefficient, coefficient The way the subscripts i and j are defined is the same as same; Strain at various positions of the hollow traction pin The standard deviation, the way the subscripts i and j are defined is the same as same; The formula for calculating the historical average consistency coefficient is as follows: In the formula, For historical strain values, the subscripts i, j, k have the same meaning as the variables. Similarly, the subscript m represents the strain as the data from the m-th historical record; The average of historical strain values; The temperature coefficient The calculation formula is: In the formula This indicates the internal temperature of the hollow traction pin (1), in degrees Celsius. To calibrate the temperature, subscripts i, j and Subscripts have the same meaning; This refers to the longitudinal temperature influence coefficient, where i=1 represents the lateral temperature influence coefficient, and i=2 represents the lateral temperature influence coefficient. The results were determined experimentally.

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