Torque measuring device and method based on Archimedes spiral angle displacement conversion

Abstract

The invention discloses a torque measuring device and method based on Archimedes spiral corner displacement conversion. The device comprises an elastic shaft, a first displacement sensor and a second displacement sensor, and a first measuring gear and a second measuring gear which are of an integrated structure with the elastic shaft are arranged on the outer side of the elastic shaft. The two displacement sensors are respectively arranged right below the two measuring gears; carrying out a calibration experiment on the relation between the angular displacement at each measurement gear and the output quantity of the corresponding displacement sensor; calibration experiment results are processed to obtain proportionality coefficients of the two measuring gears and extreme values of output quantities of the two displacement sensors; the output quantities of the two displacement sensors in the torque loading process are collected in real time; actual measurement data is processed to obtain angular displacement variation before and after torque loading at the two measuring gears, the difference value of the two angular displacement variation is the relative torsion angle of the two ends of the elastic shaft, and the torque of the rotating shaft to be measured is calculated. The method is suitable for dynamic torque monitoring of a rotating mechanical system.

Description

Technical Field

[0001] The present invention relates to the technical field of torque measurement, and more specifically, to a torque measurement device and method based on the conversion of the torsional angle displacement of an Archimedean spiral line. Background Art

[0002] Rotary power transmission is one of the important means of power transmission in a rotary mechanical system, and the torque change of a mechanical power device is an important piece of information about its operating condition.

[0003] Currently, torque measurement solutions are mainly optimized in terms of making the torque measurement results more accurate, achieving non-contact measurement, and having characteristics such as high sensitivity and high resolution. Although there are various torque sensors currently, they can be roughly divided into strain type, stress type, and deformation type.

[0004] ① The strain type sensor refers to pasting a strain sensitive element on the surface of the shaft to be measured, and obtaining the torque signal by measuring the strain. This is a relatively traditional method, and most of these principle methods belong to contact type measurement methods. The additional mass of the sensor may damage the structure of the high-speed rotating shaft and cause vibration. For example, a resistance strain gauge torque sensor, a fiber Bragg grating torque sensor, and a surface acoustic wave torque sensor.

[0005] ② The stress type sensor measures the torque by observing the change in a corresponding physical quantity of a special material shaft under mechanical stress and combining the relationship between the shear stress on the surface of the elastic body and the torque. This principle method is sensitive to changes in environmental conditions, has a high cost, and the relationship between the corresponding physical quantity and the stress change is complex and non-linear, requiring multiple calibrations. Common stress type sensors include magnetoelastic torque sensors and photoelastic torque sensors.

[0006] ③ The deformation type torque sensor is based on the fact that a deformation angle will be generated between two cross-sections of an elastic shaft under the action of torque. By reading the magnitude of this angle, torque measurement can be achieved. Summary of the Invention

[0007] The purpose of the present invention is to overcome the deficiencies in the prior art, and a torque measurement device and method based on the conversion of the torsional angle displacement of an Archimedean spiral line are proposed. The axial torsional angle of the elastic shaft under load is linearly converted into a radial displacement amount, which has the advantages of non-contact measurement, high precision, anti-interference, dynamic response, simple installation, multi-parameter measurement, low cost, and wide application range.

[0008] The purpose of the present invention can be achieved by the following technical solutions.

[0009] A torque measurement device based on the conversion of the angular displacement of an Archimedean spiral includes an elastic shaft, a first displacement sensor, and a second displacement sensor. A first measurement gear and a second measurement gear, which are of an integral structure with the elastic shaft, are arranged on the outer side of the elastic shaft. During measurement, the first displacement sensor and the second displacement sensor are respectively placed directly below the first measurement gear and the second measurement gear.

[0010] Further, the first measurement gear and the second measurement gear have the same shape and are symmetrically arranged on the outer side of the elastic shaft. The first measurement gear, the second measurement gear, and the elastic shaft are arranged along the same axis.

[0011] Further, key grooves are provided at both ends of the elastic shaft and are used to connect the driving end motor and the rotating shaft to be measured at the load end through couplings respectively during torque measurement.

[0012] Further, the cross-sectional edge contour lines of the first measurement gear and the second measurement gear are each composed of 8 segments of Archimedean spirals. Specifically, they are obtained by symmetrically arranging a segment of Archimedean spiral multiple times, and the distance from the points on the edge line to the axis changes within [a, b]. The polar coordinate equation of this segment of Archimedean spiral is:

[0013]

[0014] Among them, ρ is the polar radius and θ is the polar angle. That is, the curve starts from θ = 0, and as the angle increases, the polar radius ρ increases uniformly.

[0015] Further, both the first displacement sensor and the second displacement sensor adopt non-contact eddy current displacement sensors.

[0016] The object of the present invention can also be achieved by the following technical solutions.

[0017] A torque measurement method based on the conversion of the angular displacement of an Archimedean spiral includes the following steps:

[0018] S1: Conduct a calibration experiment on the relationship between the angular displacement at each measurement gear and the output of the corresponding displacement sensor

[0019] Under the same conditions as the actual measurement scenario, one end of the elastic shaft is connected to the driving end motor through a coupling, and the other end is connected to a high-precision angle encoder through a coupling. The first displacement sensor and the second displacement sensor are respectively fixedly placed directly below the first measurement gear and the second measurement gear. A calibration experiment is conducted on the relationship between the output of each group of displacement sensors and the angular displacement at the measurement gear to determine the relationship between the angular displacement at each measurement gear and the output of the corresponding displacement sensor;

[0020] S2: Process the results of the calibration experiment

[0021] Process the calibration experiment results to obtain the proportionality coefficient k1 of the first measurement gear, the proportionality coefficient k2 of the second measurement gear, and the maximum value L of each period of the output L1 of the first displacement sensor 1MAX and the minimum value L 1MIN ; the maximum value L of each period of the output L2 of the second displacement sensor 2MAX and the minimum value L 2MIN ;

[0022] S3: Obtain measured data

[0023] Under the conditions of the measured scenario, replace the high-precision angle encoder connected to the elastic shaft with the rotating shaft to be measured, start the motor, and collect the output L1 of the first displacement sensor and the output L2 of the second displacement sensor in real time during the torque loading process;

[0024] S4: Process measured data

[0025] According to k1, k2, and L obtained from processing the calibration experiment results in step S2 1MAX 、L 1MIN 、L 2M 、L 2MIN , and the output L1 and L2 of the two displacement sensors collected in real time through step S3, use the inverse calculation data processing method to obtain the angular displacement change amounts Δγ1 and Δγ2 before and after torque loading at the first measurement gear 2 and the second measurement gear 3 respectively. The difference between the two angular displacement change amounts is the relative torsional angle at both ends of the elastic shaft Calculate the torque T of the rotating shaft to be measured using the following formula

[0026]

[0027] where l represents the distance between the cross-sections of the two measurement gears, G represents the shear modulus of elasticity of the elastic shaft material, and d represents the diameter of the circular shaft part of the elastic shaft between the two measurement gears;

[0028] where the process of obtaining the relative torsional angle at both ends of the elastic shaft is as follows:

[0029] Taking the first displacement sensor 5 as an example, the output of the first displacement sensor before torque loading is L 1.0 , taking the output minimum value L 1.0 before the value of L 1MIN as the origin of the function, use the proportionality coefficient k1, the maximum value L 1MAX and the minimum value L 1MIN obtained from the calibration experiment in step S2 to determine the "L1 - γ1" relationship; determine the initial rotation angle γ 1.0 before torque loading according to L 1.0 before torque loading and its rising or falling state; for L 1.1For the value, the local rotation angle γ1′ after removing the integral period part after torque loading is obtained by the same method. .1 ; During the change process of L 1MIN The number of occurrences determines the integral period number n1. From n1 and γ 1.1 ′, the angular displacement after loading torque is obtained:

[0030]

[0031] Then, the change amount Δγ1 of the angular displacement before and after torque loading at the first measuring gear is:

[0032] Δγ1 = γ 1.1 - γ 1.0

[0033] According to the same determination method as Δγ1 above, the change amount Δγ2 of the angular displacement before and after torque loading at the second measuring gear is obtained;

[0034] For the elastic shaft, there is:

[0035]

[0036] Furthermore, the specific process of the calibration experiment in step S1: The motor starts to drive the elastic shaft to rotate. The high-precision angle encoder simultaneously measures the angular displacements γ1 and γ2 of the elastic shaft at the two measuring gears. Within the range of 360° for one rotation of the elastic shaft, an angle point is selected every 5°, and the output quantities L1 and L2 of the two displacement sensors are synchronously recorded to determine the relationships between γ1 and L1, and γ2 and L2.

[0037] Furthermore, in step S2, the results of the calibration experiment are processed to obtain the proportionality coefficient k1 of the first measuring gear, the proportionality coefficient k2 of the second measuring gear, the maximum value L 1MAX and the minimum value L 1MIN of each period of the output quantity L1 of the first displacement sensor, the maximum value L 2MAX and the minimum value L 2MIN of each period of the output quantity L2 of the second displacement sensor; The specific process is as follows:

[0038] Statistically analyze the changes in the output of the displacement sensor corresponding to the change in the angular displacement, mark the turning points of the change trend, that is, the positions where the maximum and minimum values appear, to obtain L 1MAX 、L 1MI 、L 2MA 、L 2MIN, the data between the two extreme points should conform to the linear variation of the displacement sensor output with the corresponding angular displacement; the proportionality coefficients of L1 and γ1 should switch between k1 and -k1, and the proportionality coefficients of L2 and γ2 should switch between k2 and -k2. The proportionality coefficients of each linear variation region are obtained by the method of linear fitting, and the average values of the proportionality coefficients of the rising (or falling) stages of the displacement sensor output in each section are calculated to obtain k1 and k2 respectively.

[0039] The object of the present invention can also be achieved by the following technical solutions.

[0040] A torque measurement system based on the conversion of the angular displacement of an Archimedean spiral, characterized in that it includes a single-chip microcomputer, a host computer, and a torque measurement device based on the conversion of the angular displacement of an Archimedean spiral; the torque measurement device based on the conversion of the angular displacement of an Archimedean spiral collects the output quantities L1 and L2 of two displacement sensors during the torque loading process, and transmits them to the single-chip microcomputer through the IIC interface. The single-chip microcomputer stores a program to implement the measured data processing process of the above-mentioned torque measurement method based on the conversion of the angular displacement of an Archimedean spiral, obtains the torque value of the rotating shaft, and displays it on the host computer interface.

[0041] Compared with the prior art, the beneficial effects brought by the technical solution of the present invention are:

[0042] The present invention uses an elastic shaft as a torque-sensitive element and measures torque based on the principle that the elastic shaft generates torsional deformation under the action of torque. An elastic shaft measuring gear is designed using an Archimedean spiral. Measuring gears with 8 identical Archimedean spiral segments as the edges are processed at both ends of the elastic shaft. Under normal working conditions, the elastic shaft undergoes torsional deformation while rotating dynamically. The special shape structure of the elastic shaft linearly converts the torsional angle generated by the elastic shaft under torsion into a measurable radial displacement variable using the geometric characteristics of the spiral. The shape of the Archimedean spiral at the edge of the measuring gear is reasonably designed to ensure the linear relationship between the sensor output and the radial displacement, which makes the output of the eddy current displacement sensor linearly related to the torque in a cycle. This method has the advantages of integrated measurement of multiple physical quantities, non-contact measurement, anti-interference, and dynamic response, and is suitable for the high-precision and real-time measurement requirements of the angle and torque in industrial environments.

[0043] The present invention uses an eddy current displacement sensor to collect displacement information. The relationship between the angular displacement of the elastic shaft and the output of the displacement sensor is obtained through a calibration experiment, and an inverse calculation is performed at the single-chip microcomputer end to calculate the torque of the elastic shaft. The absolute torsional angle of the measuring gear can be obtained using the torque value, realizing the synchronous measurement of the angle and torque. The present invention adopts a non-contact measurement method, which has the characteristics of high precision, high dynamic response, on-line measurement, strong anti-interference ability, and integrated measurement of multiple physical quantities, and is suitable for high-precision torque monitoring and fault diagnosis in fields such as industrial transmission, new energy vehicles, and aerospace. Description of the Drawings

[0044] Figure 1 It is a schematic diagram of the torsional deformation of the elastic shaft.

[0045] Figure 2 It is a schematic diagram of the torque measurement device based on the angular displacement conversion of the Archimedean spiral in the present invention;

[0046] Markings in the figure: 1 - keyway; 2 - first measurement gear; 3 - second measurement gear; 4 - elastic shaft; 5 - first displacement sensor; 6 - second displacement sensor.

[0047] Figure 3 It is a cross-sectional view of the Archimedean spiral and the elastic shaft measurement gear.

[0048] Figure 4 It is a graph of the angular displacement - displacement sensor output relationship when the elastic shaft rotates only.

[0049] Figure 5 It is a schematic diagram of the L1-Δγ1 solving process.

[0050] Figure 6 It is a principle block diagram of the torque measurement method based on the Archimedean spiral torsion - linear displacement conversion. Specific implementation mode

[0051] The present invention will be further described below with reference to the accompanying drawings.

[0052] When the elastic shaft is subjected to a torque, torsional deformation will occur. During the torsion process, each cross-section of the elastic shaft remains a plane and its shape does not change, but each cross-section rotates relative to the axis. As Figure 1 shown, at two cross-sections A and B with a distance of l, it is manifested as a relative rotation angle

[0053] Through the analysis of the shear stress strain and statics relationship after the elastic shaft is subjected to a torque, the relative rotation angle between cross-sections A and B and the torque T of the elastic shaft is obtained:

[0054]

[0055] For the elastic shaft:

[0056]

[0057] That is:

[0058]

[0059] Among them, T represents the torque on the cross-section; l represents the distance between the two cross-sections; G represents the shear elastic modulus of the material; I Prepresents the polar moment of inertia of the cross section about the center of the circle; d represents the diameter of the circular axis portion of the elastic shaft.

[0060] Example 1

[0061] The present invention adopts a differential measurement method and proposes a torque measurement device based on the angular displacement conversion of the Archimedean spiral. Figure 2 As shown, it mainly includes an elastic shaft 4, a No. 1 displacement sensor 5, and a No. 2 displacement sensor 6. The outer side of the elastic shaft 4 is processed with a No. 1 measuring gear 2 and a No. 2 measuring gear 3 with an integral structure therewith. In order to drive the elastic shaft to rotate and apply torque, key slots 1 are provided at both ends of the elastic shaft 4, which are used to connect the driving end motor and the load end rotating shaft to be measured through a coupling during torque measurement. The No. 1 measuring gear 2 and the No. 2 measuring gear 3 are located between the two key slots 1. The No. 1 measuring gear 2 and the No. 2 measuring gear 3 have the same shape and are symmetrically arranged on the outer side of the elastic shaft 4. The No. 1 measuring gear 2, the No. 2 measuring gear 3, and the elastic shaft 4 are arranged along a coaxial line.

[0062] In the above torque measuring device, the ANSYS simulation software can be used to design the measurement area size (i.e., length l and diameter d) between the two measuring gears on the elastic shaft 4 to ensure that the torsion during the torque loading process is always elastic deformation and the deformation of the elastic shaft meets the sensitivity requirements of the displacement sensor. For example, an elastic shaft made of 6061 aluminum alloy is used as a torque sensitive element, and the torque is measured based on the principle that the elastic shaft is subjected to torsional deformation under the action of torque. The elastic shear modulus of aluminum alloy 6061 is G=26Gpa, and the length of the measurement area between the first measuring gear 2 and the second measuring gear 3 on the elastic shaft 4 is designed to be l=47mm, and the diameter of the measurement area between the first measuring gear 2 and the second measuring gear 3 on the elastic shaft 4 is d=16mm.

[0063] To ensure that the output of the displacement sensor is proportional to the torque applied to the elastic shaft, when designing the cross-sectional shape of the No. 1 measuring gear 2 and the No. 2 measuring gear 3, a metal block of the same material as the elastic shaft 4 can be selected for linear displacement measurement experiments. For example, if the elastic shaft is made of 6061 aluminum alloy, a 6061 aluminum alloy metal block is selected for linear displacement measurement experiments. The experimental data is analyzed and processed - in the corresponding relationship between the displacement and the output of the displacement sensor, the interval with the highest linear correlation is selected as the spacing range between the edge of the measuring gear and the corresponding displacement sensor, and the edge lines of the No. 1 measuring gear 2 and the No. 2 measuring gear 3 are designed accordingly.

[0064] To ensure that the distance between the elastic shaft measuring gear and the sensor always changes within the linear output region of the displacement sensor during the measurement process, the cross-sectional edge contour lines of the first measuring gear 2 and the second measuring gear 3 are both composed of 8 identical Archimedean spirals, such as Figure 3As shown, it is specifically obtained by multiple symmetries of an Archimedean spiral, and the distance from the points on the edge line to the axis changes within [a, b]. The polar coordinate equation of this section of the Archimedean spiral is:

[0065]

[0066] Among them, ρ is the polar radius and θ is the polar angle. That is, the curve starts from θ = 0, and as the angle increases, the polar radius ρ increases uniformly. The determination process of a and b is as follows: First, according to the diameter d of the measurement area of the elastic shaft 4, a reasonable range of the distance between the axis of the measurement gear and the corresponding displacement sensor is selected. During the selection process, it is necessary to ensure that this distance range is not less than the maximum value of the linear range of the displacement sensor. After selecting the distance range between the axis of the measurement gear and the displacement sensor that meets the conditions, the differences are made with the extreme values of the linear output area of the displacement sensor respectively to obtain a and b (assuming b > a).

[0067] In the above torque measurement device, both the first displacement sensor 5 and the second displacement sensor 6 adopt non-contact eddy current displacement sensors to realize the acquisition of displacement information. The eddy current displacement sensor can accurately reflect the displacement of metal materials within a small range, has low requirements for the torsional deformation of the elastic shaft, and is suitable for the elastic shafts of most metal materials. The core principle of the eddy current displacement sensor is based on electromagnetic induction and eddy current effect - when high-frequency alternating current passes through the coil, an alternating magnetic field induces eddy currents on the surface of the elastic shaft, and the secondary magnetic field generated by the eddy currents changes the impedance of the coil. By detecting the impedance change, the displacement between the elastic shaft and the coil can be calculated.

[0068] As Figure 4 shown, taking the output L1 of the first displacement sensor as an example, when L1 changes at the extreme point p corresponding to 45°, the points q and r correspond to the same ΔL. At this time, it is impossible to judge the change direction of the rotation angle only based on the change of the L1 curve. When the system starts, it is in a torque-free state. Since the angular displacements γ1 = γ2 at the measurement gear, L1 and L2 are in the same phase state. Therefore, to avoid misjudgment of the torque direction, the starting measurement point of the eddy current displacement sensor should avoid the extreme points (i.e., the starting point and the ending point positions) of the edge line of the measurement gear of the elastic shaft.

[0069] During measurement, the first displacement sensor 5 and the second displacement sensor 6 are respectively placed directly below the first measurement gear 2 and the second measurement gear 3 to collect the radial displacement of the measurement gear. The elastic shaft 4 is fixed on the test bench through bearing connecting seats at both ends. Specifically, high-precision bearings are respectively installed at both ends of the elastic shaft 4 to ensure that the elastic shaft can rotate freely. The bearings are placed in the bearing connecting seats and installed between the keyway on the side where the elastic shaft is located and the measurement gear to play a role in supporting and fixing, preventing interference from axial force and bending moment loads.

[0070] During the dynamic rotation of the elastic shaft, angular displacement will occur regardless of whether torque is applied to cause torsional deformation. Among them, the angular displacement in the torque-free state is only caused by the rotational motion, while the angular displacement after torque is applied includes two factors: torsional deformation and rotational motion. Both of these situations will cause the elastic shaft to generate an angular displacement γ, thereby causing a change in the distance between the measuring gear and the displacement sensor. Therefore, this method can also measure the overall rotation angle of the elastic shaft at the same time.

[0071] Embodiment 2

[0072] Using the torque measurement device based on the conversion of the angular displacement of the Archimedean spiral in the above Embodiment 1, the present invention also proposes a torque measurement method based on the conversion of the angular displacement of the Archimedean spiral for realizing real-time online measurement of dynamic torque. The specific steps are as follows:

[0073] S1: Conduct a calibration experiment on the relationship between the angular displacement at each measuring gear and the output of the corresponding displacement sensor

[0074] Under the actual online test conditions, factors such as the sensitivity of the displacement sensor, the material and size of the elastic shaft are all fixed values, and their influence on the relationship between L and torque and rotation angle is relatively complex, and there is a periodic linear correspondence relationship between "L-γ". Therefore, a calibration method is used to determine the relationship between the output L of the displacement sensor and the angular displacement γ.

[0075] Under the same conditions as the actual measurement scenario, one end of the elastic shaft 4 is connected to the driving end motor through a coupling, and the other end is connected to a high-precision angle encoder through a coupling. A first displacement sensor 5 and a second displacement sensor 6 are respectively fixedly placed directly below the first measuring gear 2 and the second measuring gear 3. A calibration experiment is conducted on the relationship between the output of each group of displacement sensors and the angular displacement at the measuring gear to determine the relationship between the angular displacement at each measuring gear and the output of the corresponding displacement sensor.

[0076] The specific calibration process: The motor starts to drive the elastic shaft 4 to rotate, and the high-precision angle encoder simultaneously measures the angular displacements γ1 and γ2 of the elastic shaft at the two measuring gears. Within the range of 360° of one rotation of the elastic shaft, an angle point is selected every 5°, and the outputs L1 and L2 of the two displacement sensors are synchronously recorded to determine the relationships between γ1 and L1, and γ2 and L2.

[0077] S2: Process the results of the calibration experiment

[0078] In the calibration experiment results, since the two measuring gears are obtained by symmetry of multi-segment Archimedean spiral lines, the output quantities L1 and L2 of the first displacement sensor 5 and the second displacement sensor 6 should show periodic linear changes, and the proportionality coefficient between L1 and γ1 should switch between k1 and -k1, and the proportionality coefficient between L2 and γ2 should switch between k2 and -k2. Process the calibration experiment results of step S1 to obtain the proportionality coefficient k1 of the first measuring gear, the proportionality coefficient k2 of the second measuring gear, and the maximum value L of each period of the output quantity L1 of the first displacement sensor 1MAX and the minimum value L 1MIN 、the maximum value L of each period of the output quantity L2 of the second displacement sensor 2MA and the minimum value L 2MIN .

[0079] k1, k2, L 1MAX 、L 1MIN 、L 2MAX 、L 2MIN The specific determination process: Statistically analyze the changes in the output of the displacement sensor corresponding to the angular displacement change, mark the turning points of the change trend, that is, the positions where the maximum and minimum values appear, to obtain L 1MAX 、L 1MIN 、L 2MAX 、L 2MIN . The data between the two extreme points should conform to the linear change of the displacement sensor output with the corresponding angular displacement. The proportionality coefficient between L1 and γ1 should switch between k1 and -k1, and the proportionality coefficient between L2 and γ2 should switch between k2 and -k2. Use the method of linear fitting to obtain the proportionality coefficient of each linear change region, and calculate the average value of the proportionality coefficients in the rising (or falling) stage of the output of each displacement sensor to obtain k1 and k2 determined under this measurement condition respectively.

[0080] S3: Acquisition of measured data

[0081] Under the measured scene conditions, at this time, only need to replace the high-precision angle encoder connected to the elastic shaft 4 with the rotating shaft to be measured at the load end, keep other experimental conditions unchanged, start the motor to drive the rotation, and collect the output quantities L1 and L2 of the two displacement sensors in real time during the torque loading process.

[0082] S4: Processing of measured data

[0083] According to k1, k2, L 1MAX 、L 1MIN 、L 2MAX 、L 2MIN, the output values L1 and L2 of the two displacement sensors collected in real time through step S3 are used to obtain the angular displacement change amounts Δγ1 and Δγ2 before and after torque loading at the first measuring gear 2 and the second measuring gear 3 respectively by using the following inverse calculation data processing method.

[0084] Taking the first displacement sensor 5 as an example, before torque loading (when the motor is not started), the output value of the first displacement sensor is L 1.0 (initial position), taking L 1.0 value of the previous output minimum value L 1MIN as the function origin, using the proportionality coefficients k1, maximum value L 1MAX , minimum value L 1MIN obtained from the calibration experiment in step S2 to determine the "L1-γ1" relationship, as Figure 5 shown. At this time, the function origin can be known. According to L 1.0 before torque loading and its rising or falling state, determine the initial rotation angle γ 1.0 before torque loading; for the L 1.1 value after torque loading, use the same method to obtain the local rotation angle γ1′ .1 after removing the integral cycle part after torque loading. Determine the number of integral cycles n1 through the number of times L 1MIN appears during the change process, and obtain the angular displacement after loading torque from n1 and γ 1.1 ′:

[0085]

[0086] Then the angular displacement change amount Δγ1 before and after torque loading at the first measuring gear is:

[0087] Δγ1 = γ 1.1 - γ 1.0 (6)

[0088] According to the same determination method as Δγ1 above, obtain the angular displacement change amount Δγ2 before and after torque loading at the second measuring gear.

[0089] For the elastic shaft (assuming Δγ1 > Δγ2):

[0090]

[0091] The difference between the two angular displacement change amounts is the relative torsional angle at both ends of the elastic shaft Use the following formula to calculate the torque T of the measured rotating shaft:

[0092]

[0093] Among them, l represents the distance between the cross-sections of the two measuring gears, G represents the shear elastic modulus of the elastic shaft material, and d represents the diameter of the circular shaft part of the elastic shaft between the two measuring gears.

[0094] Embodiment 3

[0095] Based on the above principle, the present invention also proposes a torque measurement system based on the conversion of the rotation angle displacement of the Archimedes spiral, including a single-chip microcomputer, a host computer, and the torque measurement device based on the conversion of the rotation angle displacement of the Archimedes spiral in Embodiment 1, as Figure 6 shown, where A and B are respectively at the first measurement gear and the second measurement gear. The torque measurement device based on the conversion of the rotation angle displacement of the Archimedes spiral collects the output quantities L1 and L2 of the two displacement sensors during the torque loading process, and transmits them to the single-chip microcomputer through the IIC interface. The single-chip microcomputer stores the program to implement the measured data processing process of the torque measurement method based on the conversion of the rotation angle displacement of the Archimedes spiral in Embodiment 2, and obtains the torque value T of the rotating shaft. Serial communication is carried out between the single-chip microcomputer and the host computer, and the torque value T is displayed on the host computer interface to realize torque measurement.

[0096] The present invention utilizes the unique characteristic of the Archimedes spiral of equal-speed radial expansion to linearly convert the axial torsion angle and rotation angle of the elastic shaft under load into radial displacement quantities, and combines non-contact eddy current displacement sensors to achieve accurate calculation of torque. This method has the advantages of non-contact measurement, strong anti-interference ability, and high precision.

[0097] Although the functions and working processes of the present invention are described above in conjunction with the drawings, the present invention is not limited to the above specific functions and working processes. The above specific embodiments are merely illustrative and not restrictive. Under the inspiration of the present invention, those of ordinary skill in the art can also make many forms without departing from the spirit and scope protected by the claims of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. A torque measurement device based on the conversion of the angular displacement of an Archimedean spiral, characterized in that It includes an elastic shaft (4), a first displacement sensor (5), and a second displacement sensor (6). A first measuring gear (2) and a second measuring gear (3) which are of an integral structure with the elastic shaft (4) are arranged on the outer side of the elastic shaft (4). During measurement, the first displacement sensor (5) and the second displacement sensor (6) are respectively placed directly below the first measuring gear (2) and the second measuring gear (3).

2. The torque measuring device based on the conversion of the angular displacement of the Archimedes spiral according to claim 1, characterized in that, The first measuring gear (2) and the second measuring gear (3) have the same shape and are symmetrically arranged on the outer side of the elastic shaft (4). The first measuring gear (2), the second measuring gear (3), and the elastic shaft (4) are arranged along the same axis.

3. The torque measuring device based on the conversion of the angular displacement of the Archimedes spiral according to claim 1, characterized in that, Key grooves (1) are provided at both ends of the elastic shaft (4) and are used to connect the driving end motor and the rotating shaft to be measured at the load end through couplings respectively during torque measurement.

4. The torque measuring device based on the conversion of the angular displacement of the Archimedes spiral according to claim 1, characterized in that The cross-sectional edge contour lines of the first measuring gear (2) and the second measuring gear (3) are each composed of 8 segments of Archimedean spiral lines. Specifically, they are obtained by symmetrically arranging a segment of Archimedean spiral line multiple times, and the distance from the points on the edge line to the axis changes within [a, b]. The polar coordinate equation of this segment of Archimedean spiral line is: where ρ is the polar radius and θ is the polar angle, that is, the curve starts from θ = 0, and as the angle increases, the polar radius ρ increases uniformly.

5. The torque measurement device based on the conversion of the angular displacement of the Archimedean spiral according to claim 1, wherein Both the first displacement sensor (5) and the second displacement sensor (6) adopt non-contact eddy current displacement sensors.

6. A torque measurement method using the torque measurement device based on the conversion of the angular displacement of an Archimedean spiral according to any one of claims 1 to 5 above, characterized in that, It includes the following steps: S1: Conduct a calibration experiment on the relationship between the angular displacement at each measuring gear and the output of the corresponding displacement sensor Under the same conditions as the actual measurement scenario, one end of the elastic shaft is connected to the driving end motor through a coupling, and the other end is connected to a high-precision angle encoder through a coupling. The first displacement sensor and the second displacement sensor are respectively fixedly placed directly below the first measuring gear and the second measuring gear. A calibration experiment is conducted on the relationship between the output of each group of displacement sensors and the angular displacement at the measuring gear to determine the relationship between the angular displacement at each measuring gear and the output of the corresponding displacement sensor; S2: Process the results of the calibration experiment Process the calibration experiment results to obtain the proportionality coefficient k1 of the first measurement gear, the proportionality coefficient k2 of the second measurement gear, the maximum value L of each period of the output L1 of the first displacement sensor 1MAX and the minimum value L 1MIN , the maximum value L of each period of the output L2 of the second displacement sensor 2MAX and the minimum value L 2MIN ; S3: Obtain the measured data Under the conditions of the actual measurement scenario, replace the high-precision angle encoder connected to the elastic shaft with the rotating shaft to be measured, start the motor, and collect the output L1 of the first displacement sensor and the output L2 of the second displacement sensor in real time during the torque loading process; S4: Process the measured data k1, k2, and L obtained by processing the calibration experiment results according to step S2 1MAX , L 1MIN , L 2MAX , L 2MIN , the output quantities L1 and L2 of the two displacement sensors collected in real time through step S3, and the data processing method of back-calculation is used to respectively obtain the angular displacement change amounts Δγ1 and Δγ2 before and after torque loading at the first measuring gear 2 and the second measuring gear 3. The difference between the two angular displacement change amounts is the relative torsional angle at both ends of the elastic shaft Calculate the torque T of the rotating shaft to be measured using the following formula where l represents the distance between the cross-sections of the two measuring gears, G represents the shear modulus of elasticity of the elastic shaft material, and d represents the diameter of the circular shaft part of the elastic shaft between the two measuring gears; Among them, the process of obtaining the relative torsional angle at both ends of the elastic shaft is as follows: is obtained as follows: Taking displacement sensor 5 as an example, the output of displacement sensor 5 before torque loading is L 1.0 , with L 1.0 The previous output minimum value L 1MIN As the origin of the function, the proportional coefficient k1 and the maximum value L obtained by the calibration experiment in step S2 are used. 1MAX , minimum value L 1MIN Determine the "L1-γ1" relationship; according to the L before torque loading 1.0 and its rising or falling state to determine the initial rotation angle γ before torque loading 1.0 ; L after torque loading 1.1 The same method is used to obtain the local rotation angle γ1 after the torque is loaded and the full cycle is removed. ′ .1 ; Through the change process L 1MIN The number of occurrences determines the number of cycles n1, which is determined by n1, γ 1.1 ′Get the angular displacement after loading torque: Then the change in angular displacement Δγ1 before and after torque loading at the first measuring gear is: Δγ1 = γ 1.1 -γ 1.0 According to the same determination method as Δγ1 above, obtain the change in angular displacement Δγ2 before and after torque loading at the second measuring gear; For the elastic shaft, there is:

7. The torque measurement method based on the conversion of the angular displacement of the Archimedes spiral according to claim 6, characterized in that The specific process of the calibration experiment in step S1: The motor starts to drive the elastic shaft to rotate, and the high-precision angle encoder simultaneously measures the angular displacements γ1 and γ2 of the elastic shaft at the two measuring gears. Within the range of 360° of one rotation of the elastic shaft, an angular point is selected every 5°, and the outputs L1 and L2 of the two displacement sensors are synchronously recorded to determine the relationships between γ1 and L1, and γ2 and L2.

8. The torque measurement method based on the conversion of the angular displacement of an Archimedean spiral according to claim 6, wherein In step S2, the calibration experiment results are processed to obtain the proportionality coefficient k1 of the first measurement gear, the proportionality coefficient k2 of the second measurement gear, the maximum value L of each period of the output L1 of the first displacement sensor 1MAX and the minimum value L 1MIN , the maximum value L of each period of the output L2 of the second displacement sensor 2MAX and the minimum value L 2MIN ; The specific process is as follows: Statistically analyze the change in the output of the displacement sensor corresponding to the angular displacement change, mark the turning points of the change trend, that is, the positions where the maximum and minimum values appear, and obtain L 1MAX 、L 1MIN 、L 2MAX 、L 2MIN , the data between the two extreme points should conform to the linear change of the displacement sensor output with the corresponding angular displacement; the proportionality coefficients of L1 and γ1 should switch between k1 and -k1, and the proportionality coefficients of L2 and γ2 should switch between k2 and -k2. Use the method of linear fitting to obtain the proportionality coefficients of each linear change region, and find the average values of the proportionality coefficients of the rising (or falling) stages of the displacement sensor output for each segment to obtain k1 and k2 respectively.

9. A torque measurement system based on the conversion of the angular displacement of an Archimedean spiral, characterized in that, It includes a single-chip microcomputer, a host computer, and the torque measurement device based on the conversion of the angular displacement of the Archimedean spiral according to any one of claims 1 to 5; the torque measurement device based on the conversion of the angular displacement of the Archimedean spiral collects the output quantities L1 and L2 of two displacement sensors during the torque loading process, and transmits them to the single-chip microcomputer through the IIC interface. The single-chip microcomputer stores a program to implement the measured data processing process of the above-mentioned torque measurement method based on the conversion of the angular displacement of the Archimedean spiral, obtains the torque value of the rotating shaft, and displays it on the host computer interface.

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