A new type of resistance strain load sensor and measuring device

Abstract

The present invention provides a novel resistance strain type load sensor and measuring device, comprising: a base, a plurality of elastic bodies, a force-bearing member, an adjustment mechanism, and a plurality of strain gauges; wherein each elastic body comprises a connecting rod and a deformable member sleeved on the middle portion of the connecting rod, and each strain gauge is arranged on the corresponding deformable member; the first end of the connecting rod is detachably arranged on the base, the second end of the connecting rod is detachably connected to the adjustment mechanism, the first end of the force-bearing member abuts against the adjustment mechanism, and the second end of the force-bearing member is used to contact the object to be measured, wherein the adjustment mechanism is capable of adjusting the initial deformation values ​​of the plurality of elastic bodies; the plurality of strain gauges are used to be electrically connected to a static strain gauge, so that the plurality of strain gauges can display the deformation amount of the deformable member sensed by the multiple strain gauges on the static strain gauge, thereby solving the problem of measurement error of the existing resistance strain type load sensor due to the influence of initial stress.

Description

Technical Field

[0001] The present invention relates to the field of measurement, and in particular to a novel resistance strain type load sensor and a measuring device. Background Art

[0002] A resistance strain load sensor is a type of load sensor that produces elastic deformation under the action of an external force, causing the resistance strain gauge (conversion element) attached to its surface to also deform. After the resistance strain gauge is deformed, its resistance value will change (increase or decrease), and then the corresponding measurement circuit converts this resistance change into an electrical signal (voltage or current), thereby completing the process of converting the external force into an electrical signal. However, the initial stress of the elastic part is nonlinear, and the measured result is affected by the initial stress, which will result in errors.

[0003] In view of this, this application is filed. Summary of the Invention

[0004] The invention discloses a novel resistance strain type load sensor and a measuring device, aiming to solve the problem that the existing resistance strain type load sensor has measurement error due to the influence of initial stress.

[0005] The first embodiment of the present invention provides a novel resistance strain type load sensor, comprising: a base, a plurality of elastic bodies, a force-bearing member, an adjustment mechanism, and a plurality of strain gauges;

[0006] Wherein, each of the elastic bodies includes a connecting rod and a deformable member sleeved on the middle portion of the connecting rod, and each of the strain gauges is configured on the corresponding deformable member;

[0007] The first end of the connecting rod is detachably disposed on the base, the second end of the connecting rod is detachably connected to the adjustment mechanism, the first end of the force-bearing member abuts against the adjustment mechanism, and the second end of the force-bearing member is used to contact the object to be measured, wherein the adjustment mechanism is capable of adjusting the initial deformation values ​​of the plurality of elastic bodies;

[0008] The plurality of strain gauges are used to be electrically connected to a static strain gauge, so that the plurality of strain gauges can display the deformation amount of the deformable member sensed by the plurality of strain gauges on the static strain gauge.

[0009] Preferably, the adjustment structure includes a support plate and a plurality of adjustment members;

[0010] The second end of each connecting rod passes through the support plate, and each adjusting member is correspondingly configured on the second end of the connecting rod. The first surface of the support plate contacts the deformable member, and the second surface of the support plate contacts the force-bearing member.

[0011] The adjusting member is configured to rotate on the connecting rod to adjust the initial deformation value of the deforming member.

[0012] Preferably, it further comprises: a shell, and a cover detachably connected to the shell;

[0013] The base is arranged inside the shell, and the force-bearing member passes through the top of the cover.

[0014] Preferably, the force-bearing member includes: a first column, a second column connected to the first column, a third column connected to the second column, and a fourth column connected to the third column;

[0015] Wherein, the diameter of the second column is greater than the diameter of the first column, and the diameter of the third column is greater than the diameter of the fourth column;

[0016] The first column passes through the top of the cover, the upper surface of the second column is used to abut against the inner surface of the top of the cover, the lower surface of the third column is used to contact the support plate, and the fourth column passes through the support plate.

[0017] Preferably, an interface is provided on the side of the housing;

[0018] Wherein, the interface is used to connect the strain gauge and the static strain gauge.

[0019] Preferably, the connecting rod and the deformable member are made of 45# steel.

[0020] A second embodiment of the present invention provides a measuring device, comprising: a static strain gauge and a novel resistance strain type load sensor as described above, wherein the static strain gauge is electrically connected to the plurality of strain gauges.

[0021] Based on a new type of resistance strain load sensor and measuring device provided by the present invention, the initial deformation values ​​of multiple elastic bodies are adjusted by the adjustment mechanism, so that the relationship between stress and strain is linearized. The second end of the force-bearing member contacts the object to be measured, and the first end of the force-bearing member contacts the elastic body through the adjustment mechanism. The strain gauge can sense the deformation of the elastic body and display it on the static strain gauge, thereby solving the problem of error in measurement results of existing resistance strain load sensors due to the influence of initial stress. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 1 is a schematic diagram of the expanded structure of a novel resistive strain gauge load sensor provided by the first embodiment of the present invention;

[0023] Figure 21 is a cross-sectional schematic diagram of a novel resistance strain type load sensor provided by the present invention;

[0024] Figure 3 is a schematic diagram of the elastic body and the adjustment mechanism provided by the present invention being installed on a base;

[0025] Figure 4 is a cross-sectional view of the elastic body and the adjustment mechanism provided by the present invention installed on the base;

[0026] Figure 5 Schematic diagram of the structure of the elastomer provided by the present invention;

[0027] Figure 6 This is a schematic diagram of the stress-strain curve of 45# steel provided by the present invention;

[0028] Figure 7 This is a schematic diagram of a half-bridge circuit provided by the present invention. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the invention for which protection is sought, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0030] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0031] The invention discloses a novel resistance strain type load sensor and a measuring device, aiming to solve the problem that the existing resistance strain type load sensor has measurement error due to the influence of initial stress.

[0032] See also Figures 1 to 5 , the first embodiment of the present invention provides a novel resistance strain type load sensor, comprising: a base 3, a plurality of elastic bodies 2, a force-bearing member 9, an adjustment mechanism 1, and a plurality of strain gauges 4;

[0033] Each of the elastic bodies 2 includes a connecting rod 21 and a deformable member 22 sleeved on the middle portion of the connecting rod 21 , and each of the strain gauges 4 is disposed on the corresponding deformable member 22 ;

[0034] The first end of the connecting rod 21 is detachably disposed on the base 3, and the second end of the connecting rod 21 is detachably connected to the adjustment mechanism. The first end of the force-bearing member 9 abuts against the adjustment mechanism 1, and the second end of the force-bearing member 9 is used to contact the object to be measured, wherein the adjustment mechanism 1 is capable of adjusting the initial deformation values ​​of the plurality of elastic bodies 2;

[0035] The plurality of strain gauges 4 are used to be electrically connected to a static strain gauge, so that the plurality of strain gauges 4 can display the deformation amount of the deformable member 22 sensed by the plurality of strain gauges 4 on the static strain gauge.

[0036] It should be noted that the inventors have discovered that the resistance strain type load sensor will produce elastic deformation under the action of external force. However, the initial stress of the elastic member is nonlinear, and the measured result is affected by the initial stress and may have errors.

[0037] In this embodiment, the initial deformation values ​​of the plurality of elastic bodies 2 are adjusted by the adjustment mechanism 1, so that the relationship between stress and strain is linearized. The second end of the force-bearing member 9 contacts the object to be measured, and the first end of the force-bearing member 9 contacts the elastic body 2 through the adjustment mechanism 1. The strain gauge 4 can sense the deformation of the elastic body 2 and display it on the static strain gauge, thereby solving the problem that the measurement results of the existing resistance strain type load sensor have errors due to the influence of the initial stress.

[0038] In a possible embodiment of the present invention, the adjustment structure includes a support plate 12 and a plurality of adjustment members 11;

[0039] The second end of each connecting rod 21 passes through the support plate 12, and each adjusting member 11 is correspondingly configured on the second end of the connecting rod 21. The first surface of the support plate 12 contacts the deformable member 22, and the second surface of the support plate 12 contacts the force-bearing member 9.

[0040] The adjusting member 11 is configured to rotate on the connecting rod 21 to adjust the initial deformation value of the deforming member 22 .

[0041] It should be noted that the first end of the connecting rod 21 can be configured with an external thread, and the base 3 can be configured with an internal thread adapted to the external thread, so that the connecting rod 21 can be detachably configured on the base 3. In other embodiments, the connecting rod 21 and the base 3 can also be fixed in other ways, which are not specifically limited here.

[0042] In this embodiment, the adjusting member 11 can be a nut, and the second end of the connecting rod 21 can be configured with an external thread. The nut can be adapted to the external thread, and can be tightened to supply a downward force to the second surface of the support plate 12, thereby causing the first surface of the support plate 12 to provide a downward force to the deformable member 22, thereby changing the initial deformation of the deformable member 22. It should be noted that when the force-bearing member 9 receives an external force, it is transmitted to the deformable member 22 through the support plate 12, and the deformation of the strain gauge 4 can be sensed and displayed by the static strain gauge. When the force-bearing member 9 receives the force, its stress-strain curve changes linearly, which can improve the measurement accuracy.

[0043] In a possible embodiment of the present invention, the present invention further includes: a housing 6, and a cover 5 detachably connected to the housing 6;

[0044] The base 3 is disposed inside the housing 6 , and the force-bearing member 9 passes through the top of the cover 5 .

[0045] It should be noted that the shell 6 can be fixed on the base 3, and the shell 6 and the cover 5 can be matched through internal threads and external threads to achieve a detachable connection, which can protect the elastomer 2 and prevent the elastomer 2 from being damaged.

[0046] In a possible embodiment of the present invention, an interface 7 is provided on the side of the housing 6;

[0047] The interface 7 is used to connect the strain gauge 4 and the static strain gauge.

[0048] It should be noted that the static strain gauge may include a voltage source, which can be electrically connected to the strain gauge 4 through the interface 7, wherein the static strain gauge can also sense the voltage change caused by the deformation of the strain gauge 4 through the interface 7, and then measure the gravity of the object to be measured.

[0049] In a possible embodiment of the present invention, the force-bearing member 9 includes: a first column, a second column connected to the first column, a third column connected to the second column, and a fourth column connected to the third column;

[0050] Wherein, the diameter of the second column is greater than the diameter of the first column, and the diameter of the third column is greater than the diameter of the fourth column;

[0051] The first column passes through the top of the cover 5 , the upper surface of the second column is used to abut against the inner surface of the top of the cover 5 , the lower surface of the third column is used to abut against the support plate 12 , and the fourth column passes through the support plate 12 .

[0052] It should be noted that the top of the first column is hemispherical, and the hemispherical top is used to contact the object to be measured. It can transmit the force it receives to the support plate 12 through the lower surface of the third column, and the support plate 12 then feeds back the force to the strain gauge 4, causing the strain gauge 4 to deform.

[0053] In a possible embodiment of the present invention, a gasket 8, such as a rubber gasket, may be disposed between the upper surface of the second column and the top inner surface of the cover 5, which can prevent impurities from entering the housing 6 through the opening into the cover 5, thereby affecting the service life of the resistive strain load sensor.

[0054] In a possible embodiment of the present invention, the connecting rod 21 and the deformable member 22 may be made of 45# steel.

[0055] It should be noted that, in other embodiments, the connecting rod 21 and the deformable member 22 may also be made of other materials, which are not specifically limited here, but these solutions are all within the scope of protection of the present invention.

[0056] The scheme of the present invention is briefly described below:

[0057] There is a stage on the stress-strain curve of 45# steel called the linear elastic region. In this section, stress and strain are directly proportional. The load sensor uses this linear characteristic to measure heavy objects. The stress-strain curve of 45# steel at room temperature is as follows: Figure 6 shown.

[0058] The elastic limit of 45# steel is 420Mpa. The elastic limit is the maximum stress that can be sustained in the linear stage. If the applied stress is greater than the elastic limit, some of the material will be permanently deformed. After unloading, the material will not completely return to its original shape. The safety factor is 1.5, so the maximum allowable stress is

[0059]

[0060] In this structure, the area A1 of the outer steel single structure is:

[0061] A1=π(R 2 -r 2 )=π×(15 2 -13.5 2 )=134mm 2

[0062] Between 20 MPa and 450 MPa, the relationship between stress and strain is linearized. However, because the safety factor allows the stress to be controlled below 280 MPa, the linear range should be controlled between 20 MPa and 280 MPa. It should be noted that the contact area refers to the contact area between the deformable member 22 and the support plate 12.

[0063] During the operation of the double steel structure, the outer steel is under compression and the inner steel is under tension. The applied preload is the stress in the middle of the linear range. This allows the instrument to have good safety performance and measurement range. Therefore, the applied preload should be:

[0064]

[0065] The corresponding stress value after applying preload is σ m =150Mpa, set the state after applying preload force to 0 state, considering the external steel, the maximum force that a single piece can withstand is:

[0066] F1=(σ max -σ m )A=(280-150)×134=17420N

[0067] In a possible embodiment of the present invention, since the elastic body 2 is a double steel structure, four groups of such double steel structures can be used. After the load G is applied, the outer steel body of the double steel structure is compressed (i.e., the deformable member 22 is compressed), and the pressure increases compared to the state of 0, and the pressure increase value is F1. The inner steel body is tensile (i.e., the connecting rod 21 is tensile), and the tension is reduced compared to the state of 0, and the tension reduction value is F2. The radius of the inner steel is 10 mm and the area is A2. Since the deformation of the two steels in the double steel structure is the same, their stress and strain are the same.

[0068] F1=σ×A1,F2=σ×A2

[0069]

[0070] The maximum force that the entire instrument can withstand is:

[0071] F 总 =G=4×57486=229944N

[0072]

[0073] Therefore, the measurable range of this instrument is 0 to 23463 kg.

[0074] It should be noted that in this embodiment, if the measurement range needs to be adjusted, the number of elastic bodies 2 (i.e., the dual steel structure) can be changed, for example, to six. Of course, the structure of the elastic body 2 can also be adjusted, for example, the contact area between the deformable member 22 and the support plate 12 can be adjusted. These solutions can be configured accordingly based on actual conditions and are not specifically limited here, but all of these solutions are within the scope of protection of the present invention.

[0075] The working principle of strain gauge resistance sensor: When a conductor or semiconductor is subjected to external force, a piezoresistive effect will occur, causing its resistance value to change. At this time, by measuring the size of the resistance value, the size of the external force can be reflected. The resistance type strain gauge 4 sensor can use a bridge measurement circuit. The double steel structure adopts a half-bridge connection method, such as Figure 7 shown.

[0076] The circuit of the half-bridge connection method is connected to four strain gauges 4, two of which are under pressure and the other two are not under force.

[0077] If R1R3=R2R4, then the bridge output voltage Uab=0, and the bridge is said to be in a balanced state. If R1R3≠R2R4, then the bridge is in an unbalanced state, and the bridge output voltage is:

[0078]

[0079] Properly selecting the resistors can eliminate the influence of the bridge's constant output, making the output voltage dependent solely on the strain gauge 4. When the bridge resistance change is much smaller than its own resistance, the bridge's output voltage is proportional to the algebraic sum of the resistance changes in each arm. Therefore, the bridge's output voltage can reflect the resistance change caused by the measured value. That is, when ΔR < < R, the output voltage is:

[0080]

[0081] This product uses identical resistors, so R1 = R2 = R3 = R4. However, only R1 and R3 are subject to force, and the force applied is identical, resulting in a change in resistance. Because the force applied is identical, their resistance changes by the same amount: ΔR1 = ΔR3. R2 and R4 are not subject to force, so their resistance does not change. Therefore, the output voltage is:

[0082]

[0083] The instrument connects the wires of the strain gauge 4 to a static strain gauge via an external interface 7. Using the static strain gauge, a half-bridge method is used to measure stress and strain via the changes in the resistance voltage of the elastic body 2. The calibration factor (sensitivity) of the load cell is first calibrated using a known weight. The strain value measured by the static strain gauge is then measured to calculate the weight of the load-bearing object.

[0084] The above embodiment has at least the following beneficial effects:

[0085] The dual-steel resistance strain gauge load cell is a new type of load cell. By designing the elastic element 2 as a dual-steel structure, the load cell's measuring range is increased to 50 tons or even more. The optimal linear region of the elastic element 2 can be selected, improving measurement accuracy. This load cell is simple, convenient, and economical, offering broad application prospects and value.

[0086] A second embodiment of the present invention provides a measuring device, comprising: a static strain gauge and a novel resistance strain type load sensor as described above, wherein the static strain gauge is electrically connected to the plurality of strain gauges 4 .

[0087] Based on a new type of resistance strain load sensor and measuring device provided by the present invention, the initial deformation values ​​of multiple elastic bodies 2 are adjusted by the adjustment mechanism 1, so that the relationship between stress and strain is linearized. The second end of the force-bearing member 9 contacts the object to be measured, and the first end of the force-bearing member 9 contacts the elastic body 2 through the adjustment mechanism 1. The strain gauge 4 can sense the deformation of the elastic body 2 and display it on the static strain gauge, thereby solving the problem of error in the measurement results of the existing resistance strain load sensor due to the influence of initial stress.

[0088] The above are only preferred embodiments of the present invention. The protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention.

Claims

1. A resistance strain type load sensor, characterized in that: include: A base, a plurality of elastic bodies, a force-bearing member, an adjustment mechanism, and a plurality of strain gauges; Each of the elastic bodies includes a connecting rod and a deformable member sleeved on the middle portion of the connecting rod, and each of the strain gauges is configured on the corresponding deformable member. The elastic body is a double steel structure, and there are four of them. During the operation of the double steel structure, the outer steel body of the double steel structure, i.e., the deformable member, is compressed, and the pressure increases compared to the zero state; the inner steel body, i.e., the connecting rod, is tensile, and the tension decreases compared to the zero state. The applied preload is a stress at the middle value of the linear range. The first end of the connecting rod is detachably disposed on the base, the second end of the connecting rod is detachably connected to the adjustment mechanism, the first end of the force-bearing member abuts against the adjustment mechanism, and the second end of the force-bearing member is used to contact the object to be measured, wherein the adjustment mechanism is capable of adjusting the initial deformation values ​​of the plurality of elastic bodies; The multiple strain gauges are used to be electrically connected to the static strain gauge so that the multiple strain gauges will display the deformation amount of the deformable part sensed by the multiple strain gauges on the static strain gauge; the adjustment mechanism includes a support plate and multiple adjustment parts; wherein, the second end of each connecting rod passes through the support plate, and each adjustment part is correspondingly configured on the second end of the connecting rod, the first surface of the support plate contacts the deformable part, and the second surface of the support plate contacts the force-bearing part; the adjustment part is configured to rotate on the connecting rod to adjust the initial deformation value of the deformable part.

2. A resistance strain type load sensor according to claim 1, characterized in that: Also includes: A shell and a cover detachably connected to the shell; The base is arranged inside the shell, and the force-bearing member passes through the top of the cover.

3. A resistance strain type load sensor according to claim 2, characterized in that: The force-bearing member includes: a first column, a second column connected to the first column, a third column connected to the second column, and a fourth column connected to the third column; Wherein, the diameter of the second column is greater than the diameter of the first column, and the diameter of the third column is greater than the diameter of the fourth column; The first column passes through the top of the cover, the upper surface of the second column is used to abut against the inner surface of the top of the cover, the lower surface of the third column is used to contact the support plate, and the fourth column passes through the support plate.

4. A resistance strain type load sensor according to claim 2, characterized in that: The side of the shell is provided with an interface; Wherein, the interface is used to connect the strain gauge and the static strain gauge.

5. The resistance strain type load sensor according to claim 1, characterized in that: The connecting rod and the deformable member are made of 45# steel.

6. A measuring device, characterized in that: include: A static strain gauge and a resistance strain type load sensor according to any one of claims 1 to 5, wherein the static strain gauge is electrically connected to the plurality of strain gauges.

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