A gear

Abstract

The present invention provides a gear, belonging to the field of intelligent devices, the gear includes a gear and a speed detection device, the gear end face is provided with a groove, and the speed detection device is embedded in the groove. The speed detection device includes a cube shell, a first physical signal acquisition module, a second physical signal acquisition module, a third physical signal acquisition module, a steel needle, a Bluetooth module and a steel ball; the first physical signal acquisition module is fixed to the inner side of the upper surface of the cube shell by a steel needle, and the second physical signal acquisition module and the third physical signal acquisition module are fixed to the inner side of the cube shell parallel to the gear normal vector by a steel needle; the steel ball is embedded in the cube shell, and a small hole is opened on the outer surface of the cube shell, and the Bluetooth module is fixed in the small hole. The steel ball is embedded in the cube shell. The gear has a simple structure and is suitable for the speed monitoring of gears with high requirements for stability and good transient response capability, and is suitable for working conditions that cannot be directly detected.

Description

Technical Field

[0001] The invention belongs to the field of intelligent devices, and in particular relates to a gear. Background Art

[0002] Gears are mechanical elements with teeth on the wheel rim that can continuously mesh to transmit motion and power. Gears have been used in transmission for a long time. They are widely used in mechanical transmission and the entire mechanical field. With the development of production, the smoothness of gear operation has received attention. Existing speed detection devices usually need to rotate for a long time to detect the speed accordingly, with low detection efficiency and low accuracy of speed detection.

[0003] For example, the pulse light source speed measuring device can detect the photoelectric tachometer and achieve an accuracy of 10 -6 Even higher, however, the intensity of the pulse light source is too strong, which may cause the inspector to be unable to timely discover the tachometer's ability to receive signals or the problem of the tachometer's own light source; secondly, the jump of the pulse light source signal is too ideal and cannot represent the real reflection signal of the directional reflection paper, which is quite different from the working state of the photoelectric tachometer during actual measurement. The pulse light source still has the above disadvantages when used for photoelectric tachometer detection, so it cannot be used for the detection of other types of tachometers.

[0004] With the development of technology and the further improvement of application needs, the requirements for the precision and accuracy of speed sensors are getting higher and higher. The original detection method can no longer meet the production needs of high-precision speed sensors. Therefore, there is a need for a speed sensor detection device with high detection accuracy, high detection efficiency and low misoperation rate. Summary of the invention

[0005] Aiming at the drawbacks of the gear speed sensors commonly used in AC asynchronous motors, such as slow response speed, unstable operation and photoelectric sensors, the present invention proposes a gear, including a gear and a speed detection device, wherein a groove is provided on the end face of the gear, and the speed detection device is embedded in the groove. The speed detection device includes a cube shell, a first physical signal acquisition module, a second physical signal acquisition module, a third physical signal acquisition module, a steel needle, a Bluetooth module and a steel ball; the first physical signal acquisition module is fixed to the inner side of the upper surface of the cube shell by a steel needle, and the second physical signal acquisition module and the third physical signal acquisition module are fixed to the inner side of the cube shell parallel to the gear normal vector by a steel needle; the steel ball is embedded in the cube shell, a small hole is opened on the outer surface of the cube shell, and the Bluetooth module is fixed in the small hole.

[0006] The physical signal acquisition module is a piezoelectric / piezoresistive dual-mode flexible sensor, including a piezoelectric layer and a piezoresistive layer; the piezoelectric layer is composed of a piezoelectric composite film with a microstructure and a gold electrode sprayed on the composite film; the piezoresistive layer is composed of a graphene film sprayed on the surface of the gold electrode with a microstructure and a PDMS with a microstructure; the microstructure is a regular tetrahedral microarray, and the ratio k of the upper bottom surface side length to the lower bottom surface side length of the regular tetrahedral and the array height h satisfy:

[0007]

[0008] in, is the first variable, specifically is the second variable, specifically is the third variable, specifically c ij 、e ij and k ij are the elastic stiffness constant, piezoelectric stress constant and dielectric constant respectively; a2 is the side length of the bottom surface of the regular tetrahedron; F represents pressure, t is time, R is the internal resistance of the voltmeter, and V is the output voltage of the piezoelectric layer.

[0009] Furthermore, the regular tetrahedral microarray is preferably a pyramidal microarray.

[0010] Furthermore, the height of the regular tetrahedral pyramid microarray is preferably h=40 μm.

[0011] Furthermore, the piezoelectric layer is prepared by the following method:

[0012] (1) 1 g of BTO nanoparticles was soaked in 10 mL of H2O2 at 90°C for 6 h to modify the surface of the BTO nanoparticles to obtain h-BTO powder, which was then taken out and dried.

[0013] (2) Take 0.025 g of the h-BTO powder prepared in step (1) and dissolve it in 10 mL of DMF. At the same time, take 0.225 g of P(VDF-TrFE) powder and dissolve it in another 10 mL of DMF. Then, mix the two DMF solutions evenly.

[0014] (3) Spin-coat the mixed solution in step (2) onto a silicon template having a regular tetrahedral microarray, the size of the silicon template being 1 cm*1 cm, and dry at a constant temperature until solidified into a film, then anneal at 120°C for 2 h and then cool to room temperature, and then peel off the composite film from the silicon template.

[0015] (4) Gold electrodes with a thickness of 100 nm are plated on the two surfaces of the composite film obtained in step (3), and a lead is connected to each of them. 10 mL of 0.75 mg / mL graphene solution is drop-coated on the gold electrodes with the microarray surface and dried. A lead is connected to the graphene surface to prepare a piezoelectric film with a regular tetrahedral microarray.

[0016] Furthermore, the piezoresistive layer is prepared by the following method:

[0017] (1) PDMS and curing agent were mixed evenly in a mass ratio of 10:1 and vacuum-dried to remove bubbles;

[0018] (2) Spin-coating the PDMS with bubbles removed onto a silicon template having a regular tetrahedral microarray, the size of the silicon template being 1 cm*1 cm, drying at a constant temperature until solidified into a film, and peeling off the silicon template;

[0019] (3) 10 mL of 0.75 mg / mL graphene solution was drop-coated onto the PDMS surface with the microarray and dried, and a lead was drawn out from the graphene surface to obtain a piezoresistive layer with a regular tetrahedral microarray.

[0020] Compared with the prior art, the present invention has the following beneficial effects: the physical signal acquisition module used in the gear of the present invention is a dual-mode sensor, which is used to detect the change of the potential signal caused by the gear speed and the instantaneous change of the speed. And the gear transmission state can be further inferred according to the sensor signal, and then the motion analysis and fault analysis can be performed. The physical signal acquisition module has very high sensitivity and stability, and can not only detect dynamic signals quickly and accurately; but also detect static forces according to the steady-state current value, and accurately calculate the stress state and deformation state. Steel balls are used to convert physical quantities, and the spherical shape can ensure the consistency of all directions, thereby reducing the system error. Through the dual-mode sensor, comprehensive analysis is performed to ensure data diversity. Bluetooth transmission avoids the situation of stray wire entanglement. By real-time monitoring of the working condition of the gear to analyze whether the gear is working normally, the present invention can analyze the gear working condition from the root of the transmission, and can reflect the working condition of the gear most intuitively and accurately. Based on the above characteristics, the gear structure is simple and suitable for high stability requirements, good transient response ability, and suitable for speed monitoring of working conditions that cannot be directly detected. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of the gear of the present invention;

[0022] Figure 2 It is a structural schematic diagram of a rotation speed detection device;

[0023] Figure 3 It is a structural schematic diagram of a piezoelectric / piezoresistive dual-mode sensor;

[0024] Figure 4 It is a test table for the stress process and loading rate

[0025] Figure 5 Actual pressure loading process and test result data;

[0026] Figure 6 It is a flowchart of signal transmission when the present invention works;

[0027] Figure 7 This is a schematic diagram of how gears work in a gearbox. DETAILED DESCRIPTION

[0028] like Figure 1 , 2 The figure is a schematic diagram of the gear structure of the present invention, including a gear speed detection device, wherein a groove is provided on the end face of the gear, and the speed detection device is embedded in the groove. The speed detection device includes a cube shell 1, a first physical signal acquisition module 4, a second physical signal acquisition module 2, a third physical signal acquisition module 6, a steel needle 3, a Bluetooth module 5 and a steel ball 7; the first physical signal acquisition module 4 is fixed to the inner side of the upper surface of the cube shell 1 through the steel needle 3, and the second physical signal acquisition module 2 and the third physical signal acquisition module 6 are fixed to the inner side of the cube shell 1 parallel to the gear normal vector through the steel needle 3; the steel ball 7 is embedded in the cube shell 1, and a small hole is opened on the outer surface of the cube shell 1, and the Bluetooth module 5 is fixed in the small hole.

[0029] The first, second and third physical signal acquisition modules are all piezoelectric / piezoresistive dual-mode flexible sensors, such as Figure 3 The schematic diagram of the structure of the piezoelectric / piezoresistive dual-mode sensor includes a piezoelectric layer and a piezoresistive layer; the piezoelectric layer is composed of a piezoelectric composite film with a microstructure and a gold electrode sprayed on the composite film; the piezoresistive layer is composed of a graphene film sprayed on the surface of the gold electrode with a microstructure and a PDMS with a microstructure; the microarray structure is a regular tetrahedral microarray, according to the constitutive equation of the piezoelectric effect:

[0030]

[0031]

[0032] where c ij 、e ij and k ij are the elastic stiffness constant, piezoelectric stress constant and dielectric constant, σ ij is stress, ε ij is the strain, D is the electric displacement, and E is the electric field intensity.

[0033] When the piezoelectric film is subjected to a normal force, σ11 and σ22 are both equal to 0. The above equations (2) and (3) are combined to express:

[0034]

[0035] Eliminating ε11, ε22 and ε33, we get:

[0036]

[0037] Where: D3 is the normal phase electric displacement,

[0038]

[0039]

[0040]

[0041] According to the relationship between electric field and electric potential:

[0042]

[0043] The normal electric displacement of the piezoelectric film is further obtained as:

[0044]

[0045] V is the output voltage of the piezoelectric film, and l is the thickness of the P(VDF-TrFE) film.

[0046] According to Maxwell's equations and Ohm's law, the magnitude of the current I is related to the electric displacement D3, the voltage V and the resistance R, according to the relationship between them:

[0047]

[0048]

[0049] Where t is time, A is the force area of ​​the piezoelectric film. After eliminating the current I and the electric displacement D3, we get:

[0050]

[0051] again

[0052]

[0053] According to the initial condition V (t＝0) =0, the output voltage V is:

[0054]

[0055] Where:

[0056]

[0057] In order to further improve the piezoelectric effect of the piezoelectric film, a regular tetrahedral micro-array structure is introduced on the surface of the planar film. Compared with the planar film structure, Figure 1 As shown, the cross-sectional area of ​​the tetrahedral structure in the vertical direction is different, and the normal stress σ on the piezoelectric film is 33 The stress in the vertical direction is equal, while the stress σ of the tetrahedron on the vertical section is 33 are different.

[0058] Assume that the side length of the top surface of the tetrahedron is a1, the side length of the bottom is h, and the height is h. Then the average stress of the tetrahedron can be expressed as:

[0059]

[0060] In the formula, the geometric parameter k is defined as a2 / a1. When k = 1, the area of ​​the top surface of the regular tetrahedron is equal to the area of ​​the bottom surface, and it can be regarded as a micro unit of the plane film. From formula (17), it can be seen that when the height h of the tetrahedron and the bottom side length a2 remain unchanged, the smaller the top side length a1 is, the greater the average stress σ' 33 In order to obtain the output voltage value between the upper and lower end faces of the regular tetrahedron, the average stress σ'33 is substituted into

[0061]

[0062] It follows that:

[0063]

[0064] From formula (1), it can be seen that the output voltage of the piezoelectric sensor is proportional to the geometric parameters k and height h of the regular tetrahedral microstructure. Therefore, in order to improve the sensing performance of the piezoelectric sensing layer, the area of ​​the top surface of the microstructure should be reduced as much as possible and the height of the microstructure should be increased. Therefore, when the regular tetrahedral is a pyramid structure, the sensing performance of the piezoelectric layer reaches the best. When the base of the pyramid microstructure is extended to 60μm, the maximum height that can be prepared by the current microstructure processing technology is 40μm.

[0065] The physical signal acquisition module is prepared by the following method:

[0066] Preparation of piezoelectric layer:

[0067] (1) 1 g of BTO nanoparticles was added to a H2O2 (35%, 10 mL) solution and ultrasonicated for 1 h to fully disperse the BTO nanoparticles in the H2O2 solution. The solution was then kept at 100°C for 8 h, centrifuged and dried in an oven at 70°C.

[0068] (2) Take 25 mg of the h-BTO nanoparticles prepared in (1) and disperse them in 10 ml of N,N-dimethylformamide (DMF) by ultrasonic dispersion for 1 h.

[0069] (3) 225 mg of PVDF-TrFE powder was dissolved in 10 ml of DMF, and the two solutions were mixed and mechanically stirred for 4 h.

[0070] (4) Spin-coat the h-BTO / P(VDF-TrFE) solution on a silicon template with a size of 1cm*1cm and set the working speed to 1000r / min. The whole process is divided into three stages, the first of which is the startup stage, in which the suction cup is stably accelerated to the working speed. When the speed reaches the target, slowly drip the solution onto the silicon template and maintain the speed for 30s to evenly cover the silicon template with the solution. In the third stage, the speed is reduced to zero, and the coating process is completed.

[0071] (5) Take out the silicon template covered with the solution, put it into a vacuum drying oven and dry it at a constant temperature of 80°C for about 1 hour. After solidification into a film, anneal it at 120°C for 2 hours to improve the crystallinity of the piezoelectric film. After cooling to room temperature, the film is peeled off from the silicon template, so that a pyramid microstructure array is prepared on one side of the piezoelectric film.

[0072] (6) Gold electrodes were prepared on the upper and lower surfaces of the film using electron beam evaporation technology, and two copper wires were connected to each end of the upper and lower electrodes using silver glue. rGO was spin-coated onto the pyramid microstructure of the piezoelectric layer as the upper electrode of the piezoresistive layer.

[0073] Preparation of piezoresistive layer:

[0074] (1) First, the surface of the silicon template with microstructure is hydrophobic. The size of the silicon template is 1cm*1cm

[0075] , PDMS and curing agent were mixed evenly in a mass fraction ratio of 10:1, and air bubbles were removed by vacuum.

[0076] (2) PDMS is then spin-coated (1000 rpm / min) onto the hydrophobic treated surface and heated for curing. After the PDMS is cured into a film, the PDMS is peeled off from the silicon template surface in deionized water to obtain a PDMS surface with a pyramid microstructure.

[0077] (3) After drying at room temperature, the PDMS surface with the pyramid microstructure is plasma treated to enhance the hydrophilicity of PDMS so that the graphene sheets in the solution can be evenly distributed on the microstructure surface.

[0078] (4) Spin-coat the rGO solution (0.75 mg / mL) on the PDMS surface with pyramid microstructures, heat and dry, and then spin-coat the rGO solution 10 times (500 rpm / min). Finally, connect the copper wire on the rGO layer with silver glue.

[0079] (5) Finally, packaging is performed. The packaging material used is PDMS purchased from the American company Daconin. The ratio of PDMS to curing agent is 10:1. During the device packaging process, PDMS is first spin-coated on a glass culture dish and placed in an oven at 80°C for 5 minutes. When the PDMS is in a semi-cured state, it is removed from the oven and the piezoelectric layer is attached to the semi-cured PDMS film. The piezoresistive layer is attached to another semi-cured PDMS film in the same way.

[0080] When the gear starts to rotate, due to the initial inertia, the steel ball hits the first physical signal acquisition module. When the gear rotates in different directions, the steel ball hits the physical signal acquisition module (the second or third physical signal acquisition module) on different sides. The rotation direction of the gear is determined by detecting the positive and negative pulse signals of the piezoelectric layer of the physical signal acquisition module. When the gear starts to accelerate, due to the centrifugal force, the steel ball will squeeze the first physical signal acquisition module located on the steel ball. The pressure on the first physical signal acquisition module increases with the increase of acceleration, and the current value output by the piezoresistive layer will also increase. When the gear rotates at a constant speed, the force on all physical signal acquisition modules remains unchanged. After eliminating interference, the piezoresistive signal remains stable. When the gear accelerates, the steel ball accelerates, the force on the third physical signal acquisition module increases, and the piezoresistive signal increases. When the gear decelerates, the steel ball also decelerates after a certain delay, the force on the third physical signal acquisition module decreases, the piezoresistive signal decreases, and after a short delay, the force on the second physical signal acquisition module increases, and the piezoresistive signal increases. The steel ball converts the speed signal during mechanical movement into pressure, which acts on the physical signal acquisition module.

[0081] Note: If the gear working plane is horizontal, the steel ball gravity has no effect. If the steel ball works on other planes, the direction of gravity can be determined by integral calculation of its position (the steel ball position is relatively fixed to the cube shell), thereby eliminating gravity interference and achieving optimization.

[0082] According to Newton's second law and the centrifugal force formula, the force signal is converted into acceleration and speed signals. The physical signal acquisition module in the gear enables the piezoelectric sensing mechanism and the piezoresistive sensing mechanism to cooperate with each other, completing functions that a single-mode sensor cannot achieve. It can not only detect static force changes, but also feedback high-frequency signal stimulation, and obtain more information in the process of detecting the force or deformation of the object.

[0083] During the pressure loading process, the dual-mode sensor outputs piezoelectric and piezoresistive signals simultaneously. Figure 4The waveform diagram of the piezoelectric signal and the piezoresistive signal is shown in Figure 2. The pressure magnitude, pressure direction, and pressure loading and unloading rate during the pressure loading process can be inferred from the piezoelectric signal and the piezoresistive signal.

[0084] First, the direction of pressure can be determined based on the positive and negative values ​​of the piezoelectric signal and the change in the current value. When the piezoelectric pulse is positive and the current signal increases, it means that the sensor is under pressure. Then, the pressure loading rate can be detected based on the size of the piezoelectric peak. When the peak value of the piezoelectric pulse is 0.22V, based on the relationship between the sensor output voltage and the loading rate V out =(r-0.1)×0.23, the pressure loading rate is calculated to be r=1.05kPa / s. At this time, the actual pressure loading rate is 1kPa / s, and the error between the test data and the actual data is only 5%. At the same time, the pressure can be detected from the piezoresistive signal. When the piezoresistive signal ΔI / I0=29.6, according to the relationship between the relative current change of the piezoresistive layer and the pressure magnitude: ΔI / I0=(P-0.015)×14.5, the pressure is calculated to be 2.06kPa. At this time, the actual pressure is 2kPa, and the sensor error is only 3%. It can be seen that the piezoresistive layer can accurately detect the pressure. In addition, when the voltage signal is negative and the current value decreases, it means that the pressure is in the unloading process; when the voltage signal is negative and the current value increases, it means that the pressure is in the reverse loading process.

[0085] Therefore, combining the piezoelectric signal and the piezoresistive signal of the dual-mode sensor can reproduce the force process of the object, such as Figure 5 As shown, the dotted line is the test result obtained by the piezoelectric signal and the piezoresistive signal, and the solid line is the actual pressure loading process. It can be seen that the pressure loading process drawn according to the test results is very close to the actual loading process, indicating that the physical signal acquisition module of the present invention has good sensing accuracy and can fully reproduce the force process of the object.

[0086] like Figure 6 The figure shows a flow chart of signal transmission during operation of the present invention. (1) During the transmission process, the gear drives the steel ball to move and touch the physical signal acquisition module, causing it to deform slightly. Due to the force-electricity conversion characteristics of the physical signal acquisition module, the force signal is converted into an electrical signal, which is transmitted to the computer via the Bluetooth module. (2) The signal received by the computer is processed to obtain acceleration data, and the real-time speed of the gear can be obtained by integrating the time.

[0087] like Figure 7 The figure shows that the gear of the present invention is used in a reduction gear box. During the operation of the reduction gear box, the gear can well detect the motion state of the invisible gear inside the gearbox. According to the gear acceleration data, its meshing condition and transmission effect can be judged. Figure 7, gear b can measure the input gear speed n1, and gear c can measure the input gear speed n2. When the rightmost small gear (number of teeth z1) on the input end is meshed with the large gear (number of teeth z2) on the output end, the maximum speed reduction is achieved. Ideally, the transmission ratio is the gear ratio, that is, However, when the gear is severely worn or damaged, i will change slightly. In addition, the small range of fluctuations in i measured by the gear can be used to calculate the side clearance of the gear meshing according to the basic parameters of the gear to improve the production process or adjust the working state of the machine to improve production efficiency.

Claims

1. A gear, characterized in that: It comprises a gear and a speed detection device, wherein a groove is provided on the end face of the gear, and the speed detection device is embedded in the groove; the speed detection device comprises a cube shell, a first physical signal acquisition module, a second physical signal acquisition module, a third physical signal acquisition module, a steel needle, a Bluetooth module and a steel ball; the first physical signal acquisition module is fixed to the inner side of the upper surface of the cube shell by the steel needle, and the second physical signal acquisition module and the third physical signal acquisition module are fixed to the inner side of the cube shell parallel to the gear normal vector by the steel needle; the steel ball is embedded in the cube shell, a small hole is opened on the outer surface of the cube shell, and the Bluetooth module is fixed in the small hole; The physical signal acquisition module is a piezoelectric / piezoresistive dual-mode flexible sensor, including a piezoelectric layer and a piezoresistive layer; the piezoelectric layer is composed of a piezoelectric composite film with a microstructure and a gold electrode sprayed on the composite film; the piezoresistive layer is composed of a graphene film sprayed on the surface of the gold electrode with a microstructure and a PDMS with a microstructure; the microstructure is a regular tetrahedral microarray, and the ratio k of the upper bottom surface side length to the lower bottom surface side length of the regular tetrahedral and the array height h satisfy: in, is the first variable, specifically is the second variable, specifically is the third variable, specifically c ij 、e ij and k ij are the elastic stiffness constant, piezoelectric stress constant and dielectric constant respectively; a2 is the side length of the bottom surface of the regular tetrahedron; F represents pressure, t is time, R is the internal resistance of the voltmeter, and V is the output voltage of the piezoelectric layer.

2. The gear according to claim 1, characterized in that: The regular tetrahedral microarray is a pyramid-shaped microarray.

3. The gear according to claim 1, characterized in that: The height of the regular tetrahedral microarray is h=40 μm.

4. The gear according to claim 1, characterized in that: The piezoelectric layer is prepared by the following method: (1) 1 g of BTO nanoparticles were soaked in 10 mL of H2O2 at 90°C for 6 h to modify the surface of the BTO nanoparticles to obtain h-BTO powder, which was then taken out and dried; (2) Take 0.025 g of the h-BTO powder prepared in step (1) and dissolve it in 10 mL of DMF. At the same time, take 0.225 g of P(VDF-TrFE) powder and dissolve it in another 10 mL of DMF. Then, mix the two DMF solutions evenly. (3) Spin coating the mixed solution in step (2) on a silicon template having a regular tetrahedral microarray, the size of the silicon template being 1 cm*1 cm, and drying at a constant temperature until solidified into a film, and then annealing at 120° C. for 2 h and then cooling to room temperature, and then peeling the composite film from the silicon template; (4) Gold electrodes with a thickness of 100 nm are plated on the two surfaces of the composite film obtained in step (3), and a lead is connected to each of them. 10 mL of 0.75 mg / mL graphene solution is drop-coated on the gold electrodes with the microarray surface and dried. A lead is connected to the graphene surface to prepare a piezoelectric film with a regular tetrahedral microarray.

5. The gear according to claim 1, characterized in that: The piezoresistive layer is prepared by the following method: (1) PDMS and curing agent were mixed evenly in a mass ratio of 10:1 and vacuum-dried to remove bubbles; (2) Spin-coating the PDMS with bubbles removed onto a silicon template having a regular tetrahedral microarray, the size of the silicon template being 1 cm*1 cm, drying at a constant temperature until solidified into a film, and peeling off the silicon template; (3) 10 mL of 0.75 mg / mL graphene solution was drop-coated onto the PDMS surface with the microarray and dried, and a lead was drawn out from the graphene surface to obtain a piezoresistive layer with a regular tetrahedral microarray.

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