A high-precision flange-type large torque sensor bending moment absorption groove structure and method

Abstract

The present invention relates to a high-precision flange-type, high-torque sensor bending moment absorption groove structure and method. The structure includes a flange plate with four torque absorption grooves disposed therein, arranged on the outer and inner surfaces of the two flange plates, forming outer and inner bending moment absorption grooves. The method includes determining the aperture of the outer absorption groove, the radial width of the outer torque groove, the axial depth of the outer groove, the width and depth of the inner groove, and the radial distance between the outer and inner grooves, and verifying the structural strength of the sensor. The present invention modifies the structure of the flange plate and adds grooves to reduce the influence of axial bending moment on the strain value of the measurement area, thereby preventing interference with the torque value measured by the strain gauge, thereby improving the measurement accuracy of the flange-type torque sensor in practical applications.

Description

Technical Field

[0001] The present invention relates to a high-precision flange-type large torque sensor, and in particular to a bending moment absorption groove structure and a design method of the high-precision flange-type large torque sensor. Background Art

[0002] Torque sensors are widely used in rotating power machinery and equipment in the fields of rail transportation, aviation, aerospace, shipbuilding, marine engineering, road transportation, etc. Their measurement accuracy is of great significance for judging the operating status of the shaft system and power system and achieving equipment safety early warning.

[0003] Currently, mainstream torque sensors mostly use strain gauge methods for measurement, and their structural forms can be roughly divided into two types: one is the serial shaft type and the other is the flange type.

[0004] Tandem torque sensors have a wide range of applications, offering high measurement accuracy, fast rotational speeds, and a mature sensor structure. The principles of torque transmission are well-established, with established theoretical and empirical formulas and numerous mathematical models available for reference. However, in the field of high-torque sensors, this structural form has a significant drawback: when measuring high torques, the tandem sensor becomes extremely large, making installation difficult. For example, when measuring torques up to 200 kNm, the sensor's radial dimension is a full meter, and the shaft diameter exceeds 100 mm. If this type of sensor is not considered during the design phase, later installation of a tandem torque sensor can be extremely difficult. Therefore, tandem torque sensors are often used in applications with low torques and high rotational speeds.

[0005] Another structural type is the flange-type, similar to a rigid coupling. It connects to the shaft via two flanges, with the hollow shaft area between the two flanges serving as the measurement zone. This type of torque sensor is often used in high-torque and ultra-high-torque applications and offers higher measurement accuracy. Compared to tandem-type torque sensors, flange-type torque sensors are compact, have a wide measurement range, take up little space, and are easy to install. However, their disadvantages are their low rotational speed, making them unsuitable for ultra-high-speed applications. Furthermore, due to their structural design, flange-type torque sensors are susceptible to interference from external forces such as axial bending moments, which can affect measurement accuracy.

[0006] In order to solve the influence of axial bending moment on the measurement area and improve the measurement accuracy of the flange torque sensor, it is necessary to improve the flange torque sensor. Summary of the Invention

[0007] The present invention aims to address the impact of axial thrust, bending moment, and other factors on the measurement accuracy of flange-mounted torque sensors by providing a high-precision, high-torque sensor with a bending moment absorption groove structure and method. This structural design modifies the flange plate structure and adds grooves to reduce the impact of axial bending moment on the strain value in the measurement area. This prevents interference with the torque value measured by the strain gauge, thereby improving the measurement accuracy of the flange-mounted torque sensor in practical applications.

[0008] The present invention is achieved through the following technical solutions.

[0009] A high-precision flange-type large torque sensor bending moment absorption groove structure includes a flange plate. Four moment absorption grooves are provided in the flange plate, which are respectively arranged on the outer surface and inner surface of two flange plates to form a bending moment absorption outer groove and a bending moment absorption inner groove.

[0010] Furthermore, the dimensions of the moment absorbing outer groove are: radial width 5 mm, axial depth 17.5 mm.

[0011] Furthermore, the dimensions of the moment absorbing inner groove are: radial width 5 mm, axial depth 9 mm.

[0012] Furthermore, the distance between the moment absorbing outer groove and the moment absorbing inner groove is 15 mm.

[0013] A method for implementing a high-precision flange-type large torque sensor bending moment absorption groove structure, the specific steps are as follows:

[0014] Step 1: Determine the aperture of the outer absorption tank according to the size of the bolt hole diameter and the flange outer diameter, so that the distance from the bolt hole diameter to the flange outer diameter is equal to the distance from the bolt hole diameter to the outer absorption tank aperture;

[0015] Step 2: Determine the radial width of the torque outer groove. Apply axial bending moment to the sensor through finite element simulation analysis. Take the torque groove width as input and the bending moment absorption effect and structural strength as output. Combined with the actual size of the flange, the optimal bending moment groove width is finally obtained.

[0016] Step 3: Determine the axial depth of the outer groove. Based on the finite element simulation results, take the moment groove depth as input, the moment absorption effect and structural strength as output, and combine the actual size of the elastomer to obtain the most ideal moment groove depth.

[0017] Step 4: Determine the width and depth of the inner groove, as well as the radial distance between the outer groove and the inner groove. Taking the outer groove as the standard, first ensure that the shear stress in the outer groove does not exceed the allowable shear stress of 100 MPa. Secondly, it is necessary to ensure that the shear stress of the inner groove is also less than 100 MPa. If the conditions cannot be met, the stress concentration is alleviated by reducing the depth of the inner groove until the shear stress of the inner and outer grooves is less than 100 MPa. Finally, determine the radial distance between the inner and outer grooves, as well as the width and depth of the inner groove.

[0018] Step 5: Verify the structural strength of the sensor by using finite element simulation to ensure that the maximum stress value of the inner and outer grooves is less than 100 MPa under the rated torque load.

[0019] Furthermore, in step 2, we first assume that the groove depth is 10 mm. Based on the calculation results, we propose the relationship between the equivalent stress in the groove and the groove width:

[0020] M=-1.16d 3 +26.33d-200.13d+664

[0021] Where: M is the equivalent stress in the slot, d is the slot width;

[0022] According to the calculation results of the groove width and the stress value of the measuring area, it can be concluded that the groove width design only needs to meet the strength requirements and flange size requirements.

[0023] Furthermore, in step three, the relationship between the outer groove depth and the shear stress in the groove is fitted based on the finite element simulation results:

[0024] M 切 =3.584l 外 +37.12

[0025] Where: M 切 is the shear stress in the groove, l 外 is the outer groove depth;

[0026] Under the premise of ensuring that the shear stress in the groove does not exceed the allowable shear stress of the material, and considering the groove depth and the bending moment absorption effect, the relationship between the outer groove depth and the stress in the strain zone is fitted according to the finite element simulation results:

[0027]

[0028] Where: N is the stress in the strain measurement area, l 外 is the outer groove depth;

[0029] The conclusion is that the lower the stress, the more obvious the absorption effect.

[0030] Furthermore, in step five, the structural strength of the sensor is verified using the finite element simulation method, and the stress and strain of the elastomer with and without absorption grooves under torque and axial bending moment are analyzed and compared; the constraint conditions with and without absorption grooves are completely consistent, and a fixed constraint is applied to the bolt hole of one side flange, and a torque of 200kNm is loaded on the bolt hole of the other side flange, and an axial bending moment of 50kN is applied to one of the bolt holes. In addition, axial and radial constraints are applied to the stop to restore the actual usage conditions to the greatest extent.

[0031] The beneficial effects of the present invention are:

[0032] The present invention modifies the structure of the flange and adds grooves to reduce the influence of the axial bending moment on the strain value of the measuring area, so that the torque value measured by the strain gauge is not disturbed, thereby improving the measurement accuracy of the flange-type torque sensor in practical applications.

[0033] Finite element simulation was used to analyze and compare the stress and strain of elastomers with and without absorption grooves under torque and axial bending moment. Under axial bending moment and thrust torque, the stress in the measurement area of the sensor with absorption grooves was significantly lower than that of the sensor without absorption grooves. Furthermore, the error of the elastomer with absorption grooves under simultaneous bending moment and axial thrust was significantly lower (7.5%) than that of the elastomer without absorption grooves (10.43%), demonstrating a significant bending moment absorption effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is a schematic diagram of the torque-strain relationship of the elastic shaft;

[0035] Figure 2 This is a schematic diagram of the basic structure of the torque sensor;

[0036] Figure 3 This is a schematic diagram of the bending moment absorption groove structure of a high-precision flange-type large torque sensor;

[0037] Figure 4 is a schematic diagram of the strain measurement area;

[0038] Figure 5 is a schematic diagram of constraints;

[0039] Figure 6 is the stress value in the absorption tank;

[0040] Figure 7 is the stress value in the measurement area;

[0041] Figure 8 It is the trend diagram of outer groove depth and stress magnitude in groove;

[0042] Figure 9 It is the trend diagram of outer groove depth and stress magnitude in strain measurement area;

[0043] Figure 10 This is the relationship diagram between the inner and outer groove spacing and stress. DETAILED DESCRIPTION

[0044] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0045] A torque sensor measures torque based on the changes in physical parameters generated by an elastic shaft when transmitting torque. These changes can include deformation, strain, and other physical parameters. Common strain gauge torque sensors measure torque by attaching strain gauges to the surface of the elastic shaft. When torque is applied to the shaft, the shaft undergoes torsional deformation, generating the maximum shear strain τ in the direction of a ±45° angle with the axis. Applying a resistance strain gauge in this direction can measure the applied torque.

[0046] When the elastic shaft is subjected to torque, the torque-strain relationship can be expressed as Figure 1 analyze:

[0047] When a torque M is applied to an elastic shaft of length L, fixed at one end and the other end, the shaft will experience torsional deformation. Assuming the deformation is very small, the length and cross-sectional area of the shaft remain unchanged, and any two cross-sections rotate relative to each other around the central axis, a torsion angle is generated. When the shear stress on the shaft does not exceed the material's tolerance limit, the torque M can be expressed as

[0048]

[0049] Where: r is the radius of the cross section of the elastic axis;

[0050] Ip - polar moment of inertia of the elastic axis;

[0051] G - shear modulus of the material;

[0052] τ - Maximum shear strain at the surface of the elastic axis.

[0053] According to the above torque-strain relationship diagram, in order to measure the torque value M, it is only necessary to measure the strain τ by sticking a strain gauge on the shaft.

[0054] The basic structure of the torque sensor is as follows Figure 2 As shown in the figure, it mainly consists of an elastic body 1 (i.e., elastic sensitive element) and a strain gauge 2. The working principle of the torque sensor is to attach a resistance strain gauge to an elastic shaft. When torque M acts on the measured shaft, the shaft undergoes torsional deformation, causing the strain of the strain gauge to change, which in turn causes a relative change in the resistance of the strain gauge. The output is a voltage signal proportional to the torque. The voltage change is captured through signal acquisition technology, and the measured torque value is obtained through data processing.

[0055] Torque sensors often achieve extremely high measurement accuracy in laboratory environments, with static indication errors exceeding 0.1%. However, in actual working environments, such as those in the shipbuilding, wind power, and automotive industries, torque sensors operate in harsh environments. In the shipbuilding, wind power, and aerospace industries, the measured shafts often experience axial movement and misalignment, generating axial bending moments. Strain gauges capture these axial bending moments, affecting the normal operation of the sensor and, consequently, the measurement accuracy. Furthermore, the measured shafts often experience vibration, eccentricity, and even unequal bolt preloads, all of which can cause bending moments in the measurement area. The resulting strain signals can also be captured by the strain gauges, affecting the measurement accuracy.

[0056] The present invention aims to solve the influence of axial thrust and bending moment on the measurement area and improve the measurement accuracy of flange-type torque sensors. Taking the independently developed 200kNm torque sensor elastomer as the research object, the sensor is 3D modeled using commercial engineering software, and the flange structure is modified. Under the premise of not affecting the structural strength, a high-precision flange-type large torque sensor bending moment absorption groove structure is formed. Figure 3 As shown, four moment absorbing grooves 4 are provided in the two flanges, which are arranged on the outer and inner surfaces of the left and right flanges 3 and 5, respectively, to absorb axial bending moments.

[0057] A method for realizing an axial bending moment absorption groove of a flange-type torque sensor, the specific steps are as follows:

[0058] Step 1: Determine the aperture of the external absorption trough. Determine the aperture of the external absorption trough based on the bolt hole diameter and the flange outer diameter, making the distance from the bolt hole diameter to the flange outer diameter equal to the distance from the bolt hole diameter to the external absorption trough aperture.

[0059] Step 2: Determine the radial width of the outer moment groove. Using finite element simulation, apply axial bending moment to the sensor, using the moment groove width as input and the moment absorption and structural strength as output. Combined with the actual flange dimensions, assuming a groove depth of 10 mm, the optimal moment groove width is determined.

[0060] According to the calculation results, the relationship between the equivalent stress in the slot and the slot width is proposed:

[0061] M=-1.16d 3 +26.33d-200.13d+664

[0062] M is the equivalent stress in the tank

[0063] d is the slot width

[0064] According to the groove width and measuring area A (see Figure 4) The calculation results of the stress values show that the slot width has little effect on the absorption of bending moment. Therefore, the slot width design only needs to meet the strength requirements and flange size requirements.

[0065] Step 3: Determine the axial depth of the outer groove. Based on the finite element simulation results, the moment groove depth is used as input, the bending moment absorption effect and structural strength are used as output, and the actual size of the elastomer is combined with a groove width of 5mm to obtain the optimal moment groove depth.

[0066] According to the finite element simulation results, the relationship between the outer groove depth and the shear stress in the groove is fitted:

[0067] M 切 =3.584l 外 +37.12

[0068] M 切 : Shear stress in the groove

[0069] l 外 : Outer groove depth

[0070] On the premise of ensuring that the shear stress in the groove does not exceed the allowable shear stress of the material, the groove depth and the bending moment absorption effect are considered. According to the finite element simulation results, the relationship between the outer groove depth and the stress size in the strain zone is fitted. The lower the stress, the more obvious the absorption effect.

[0071]

[0072] N: stress in strain measurement area

[0073] l 外 : Outer groove depth

[0074] Step 4: Determine the width and depth of the inner groove, as well as the radial distance between the outer and inner grooves. Using the outer groove as a guide, first ensure that the shear stress in the outer groove does not exceed the allowable shear stress of 100 MPa. Second, ensure that the shear stress in the inner groove is also less than 100 MPa. If these conditions cannot be met, reduce the inner groove depth to alleviate stress concentration until the shear stress in both the inner and outer grooves is less than 100 MPa. Finally, determine the radial distance between the inner and outer grooves, as well as the width and depth of the inner groove.

[0075] Step 5: Verify the structural strength of the sensor. Verify the structural strength through finite element simulation to ensure that the maximum stress value of the inner and outer grooves is less than 100 MPa under the rated torque load.

[0076] Finite element simulation method is used to analyze and compare the stress and strain of elastic bodies with and without absorption grooves under torque and axial bending moment.

[0077] The constraints with and without absorption tanks are exactly the same. The constraints are as follows: Figure 5 shown.

[0078] Fixed support was applied to the bolt holes of the left flange 3, a torque of 200 kNm was applied to the bolt holes of the right flange 5, and a 50 kN axial bending moment was applied to one of the bolt holes. In addition, axial and radial support were applied to the stop to maximize the reproduction of actual usage conditions.

[0079] The simulation results are shown in the following table:

[0080]

[0081] As can be seen from the above table,

[0082] Under axial bending moment and thrust torque, the stress in the measurement area of the sensor with the absorption groove is significantly lower than that of the sensor without the absorption groove. Furthermore, the error of the elastic body with the absorption groove under the simultaneous action of bending moment and axial thrust is significantly lower (7.5%) than that of the elastic body without the absorption groove (10.43%), indicating a significant bending moment absorption effect.

[0083] Specific embodiments of the present invention:

[0084] Taking a torque sensor with an outer diameter of 550mm, a flange thickness of 40mm, and a measuring area outer diameter of 352.5mm as an example, a torque absorption groove is designed for the sensor. The specific implementation steps are as follows:

[0085] The first thing to confirm is the radial width of the inner and outer grooves. Through simulation analysis, radial widths of the absorption grooves were varied from 0 mm to 10 mm. The outputs were the stress magnitude in the strain zone and the stress within the absorption groove. Lower stress in the strain zone indicates better absorption. The stress within the absorption groove must not exceed the material's allowable equivalent stress of 180 MPa. Assuming these conditions are met, a smaller absorption groove width is more beneficial for mechanical design.

[0086] The simulation results are as follows Figure 6 , as shown in Figure 7, the calculation results show that the equivalent stress in the groove decreases as the outer groove width increases. When the groove depth is greater than or equal to 4mm, the equivalent stress is less than the allowable equivalent stress (180Mpa), and the amplitude of the reduction in the equivalent stress slows down, indicating that the stress concentration phenomenon is gradually alleviated. Therefore, the groove depth should be greater than 4mm. According to the formula, when the groove width is greater than 4.864mm, the equivalent stress is less than the allowable stress of 180Mpa. Considering processing and safety margin, the groove width is 5mm.

[0087] As can be seen from another figure, the slot width has little effect on the absorption of bending moment. Therefore, it only needs to meet the strength requirements and flange size requirements.

[0088] After determining the radial width, the next step is to determine the depth of the outer absorption groove. Through simulation analysis, groove depths ranging from 10 mm to 25 mm were simulated, with a uniform groove width of 5 mm. The output is the stress value in the strain zone and the stress value within the groove. The smaller the stress value in the strain zone, the better the bending moment absorption effect. The stress value within the groove cannot exceed the material's allowable shear stress of 100 MPa.

[0089] The simulation analysis results are as follows Figure 8 As shown in Figure 9, the calculation results show that the stress in the strain measurement area decreases with increasing groove depth, indicating that the deeper the groove, the better the bending moment absorption effect. When the groove depth is less than 20mm, the stress change is not significant. When the groove depth exceeds 20mm, this trend becomes increasingly obvious. However, the stress in the groove increases with increasing depth. When the shear stress is less than 100Mpa, the groove depth is 17.5mm.

[0090] The next step is to determine the depth of the inner absorption groove and the radial distance between the inner and outer grooves. Finite element analysis is used to analyze the radial distances of 0mm, 2.5mm, 5mm, 7.5mm, 10mm, 12.5mm, 15mm, 17.5mm, 20mm, and 22.5mm, respectively. The shear stress of the inner and outer grooves is used as the output. Under the premise of ensuring that the stress in the outer groove does not exceed 100 MPa, the depth of the inner groove and the distance between the inner and outer grooves are determined.

[0091] The calculation results are as follows Figure 10 As shown in the figure, when the distance between the inner and outer grooves is greater than 15mm, the outer groove stress is less than 100Mpa, and the inner groove shear stress is 113Mpa, exceeding the required shear stress of 100Mpa. Therefore, further structural modifications are required. The shear stress of the inner groove can be reduced by shortening the inner groove depth. When the inner groove depth is shortened to 9mm, the design requirements are met.

[0092] Through the above analysis, the outer groove aperture is determined first, and then the inner and outer groove widths, outer groove depth, inner and outer groove spacing, and inner groove depth are determined. Finally, the dimensions of the moment absorbing groove are determined as shown in the following table:

[0093] Radial width Axial depth Inner and outer groove spacing outer groove 5mm 17.5mm 15mm Inner groove 5mm 9mm 15mm

[0094] Finally, the strength and absorption effect of the elastomer are verified. Through the finite element simulation method, the constraints such as Figure 5 shown.

[0095] Fixed support was applied to the bolt holes on one side of the flange, a torque of 200 kNm was applied to the bolt holes on the other side of the flange, and a 50 kN axial bending moment was applied to one of the bolt holes. In addition, axial and radial support were applied to the stop to maximize the reproduction of actual usage conditions.

[0096] The effects of the moment absorbing grooves are shown in the following table:

[0097]

Claims

1. A method for implementing a high-precision flange-type large torque sensor bending moment absorption groove structure, the high-precision flange-type large torque sensor bending moment absorption groove structure comprising a flange plate, wherein four torque absorption grooves are provided in the flange plate, and are respectively arranged on the outer surface and inner surface of the two flange plates to form an outer groove and an inner groove, characterized in that: The specific steps of this method are as follows: Step 1: Determine the outer groove diameter based on the bolt hole diameter and flange outer diameter, making the distance from the bolt hole diameter to the flange outer diameter equal to the distance from the bolt hole diameter to the outer groove diameter; Step 2: Determine the radial width of the outer groove. Apply axial bending moment to the sensor through finite element simulation analysis. Take the outer groove width as input and the bending moment absorption effect and structural strength as output. Combined with the actual size of the flange, the optimal outer groove width is finally obtained. Step 3: Determine the axial depth of the outer groove. Based on the finite element simulation results, the outer groove depth is used as input, the bending moment absorption effect and structural strength are used as output, and the actual size of the elastic body is combined to obtain the optimal outer groove depth. Step 4: Determine the width and depth of the inner groove, as well as the radial distance between the outer groove and the inner groove. Taking the outer groove as the standard, first ensure that the shear stress in the outer groove does not exceed the allowable shear stress of 100 MPa. Secondly, the shear stress of the inner groove must also be less than 100 MPa. If these conditions cannot be met, reduce the depth of the inner groove to alleviate stress concentration until the shear stress of both the inner and outer grooves is less than 100 MPa. Finally, determine the radial distance between the inner and outer grooves, as well as the width and depth of the inner groove. Step 5: Verify the structural strength of the sensor by using finite element simulation to ensure that the maximum stress value of the inner and outer grooves is less than 100 MPa under the rated torque load.

2. The implementation method according to claim 1, characterized in that: In step 2, we first assume that the outer groove depth is 10 mm. Based on the calculation results, we propose the relationship between the equivalent stress in the groove and the outer groove width: Where: is the equivalent stress in the tank, is the outer groove width; According to the calculation results of the outer groove width and the stress value of the measuring area, it can be concluded that the outer groove width design only needs to meet the strength requirements and flange size requirements.

3. The implementation method according to claim 1, characterized in that: In step 3, the relationship between the outer groove depth and the shear stress in the groove is fitted based on the finite element simulation results: Where: is the shear stress in the groove, is the outer groove depth; Under the premise of ensuring that the shear stress in the groove does not exceed the allowable shear stress of the material, and considering the outer groove depth and the bending moment absorption effect, the relationship between the outer groove depth and the stress in the strain zone is fitted according to the finite element simulation results: Where: is the stress in the strain measurement area, is the outer groove depth; The conclusion is that the lower the stress, the more obvious the absorption effect.

4. The implementation method according to claim 1, characterized in that: In step five, the structural strength of the sensor is verified using the finite element simulation method, and the stress and strain of the elastomer with and without torque absorption grooves under torque and axial bending moment are analyzed and compared. The constraint conditions of the torque absorption groove and the elastomer without torque absorption groove are completely consistent. A fixed constraint is applied to the bolt hole of one side flange, and a torque of 200kNm is loaded on the bolt hole of the other side flange. An axial bending moment of 50kN is applied to one of the bolt holes. In addition, axial and radial constraints are applied to the stop to restore the actual usage conditions to the greatest extent.

5. The implementation method according to claim 1, characterized in that: The dimensions of the outer groove are: radial width 5 mm, axial depth 17.5 mm.

6. The implementation method according to claim 1, characterized in that: The inner groove dimensions are: radial width 5 mm, axial depth 9 mm.

7. The implementation method according to claim 1, characterized in that: The distance between the outer groove and the inner groove is 15 mm.

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