Vacuum varnishing equipment for motor windings and varnishing process thereof

Abstract

The present invention relates to the field of vacuum varnishing, and in particular to a vacuum varnishing device for motor windings and a varnishing process thereof. The varnishing process comprises: obtaining winding structural parameters of the motor winding and dynamic viscosity data of the insulating varnish, and determining initial varnishing parameters based thereon; placing the motor winding vertically in an axial direction into an immersion cylinder and pre-baking the motor winding, allowing the motor winding to cool naturally after the pre-baking, and then vacuum evacuating the immersion cylinder; injecting insulating varnish after the vacuum evacuation, and performing pressure varnishing according to the initial varnishing parameters; real-time monitoring of the temperature data of the motor winding to determine the varnishing front travel speed, and adjusting the varnishing pressure accordingly; determining a penetration depth characterization value based on the temperature data to adjust the varnishing pressure and varnishing duration; and after the pressure varnishing is completed, unloading the pressure and sequentially performing back-painting, dripping, secondary back-painting, low-temperature drying, and high-temperature curing. The present invention reduces the probability of insufficient varnish penetration of the motor winding during vacuum varnishing.

Description

Technical Field

[0001] The present invention relates to the technical field of vacuum varnishing, and in particular to vacuum varnishing equipment for motor windings and a varnishing process thereof. Background Art

[0002] Motor varnishing involves immersing motor components, particularly coils and other key components, in a specialized insulating varnish to improve their insulation and durability. This process aims to create a uniform insulation layer inside and outside the motor to prevent leakage, short circuits, and other electrical failures during operation. It also protects the motor's internal components from erosion and damage from external factors. Improving the motor's insulation and durability is an integral part of the motor manufacturing process.

[0003] The Vacuum Pressure Impregnation (VPI) insulation process involves pre-baking the workpiece to remove moisture, then cooling it and placing it in a vacuum environment to remove air and volatiles from the blank coil. The process then relies on the gravity of the paint liquid and the capillary action of the coil in the vacuum, as well as dry compressed air or inert gas, to apply a certain pressure to the impregnation paint liquid after the vacuum is released, allowing the paint liquid to quickly penetrate and fill the inner layer of the insulation structure.

[0004] However, due to differences in motor winding gap density and capillary coefficient, the insulating paint may not be able to penetrate evenly into deep gaps, resulting in insufficient penetration or voids in local areas. At the same time, the viscosity of the insulating paint changes with temperature during the dipping process, affecting the penetration efficiency, which can easily lead to over-dipping (waste of materials) or under-dipping (reduced insulation), resulting in a decrease in the quality of the dipping paint.

[0005] Chinese Patent Publication No.: CN116455161A discloses a method for vacuum dipping of permanent magnet motor rotors, comprising: applying a release agent on the outer surfaces of the two shaft bodies of the rotor shaft, the outer surface of the upper pressure plate, and the outer surface of the lower pressure plate; installing a protective sleeve on the shaft body facing upward; entering the vacuum tank for dipping; exiting the tank; primary cleaning: removing the protective sleeve, cleaning the outer surface of the upward shaft extension, cleaning the surface of the upper pressure plate and the root of the groove thereon, and cleaning the outer cylindrical surface of the rotor core; drying; secondary cleaning: cleaning the outer surface of the downward shaft extension and the surface of the lower pressure plate. The present invention has the advantages of significantly shortening the dipping and cleaning operation time, and improving the dipping and cleaning efficiency and cleaning quality. It can be seen that the above-mentioned method for vacuum dipping of permanent magnet motor rotors has the problem of insufficient penetration depth and uneven distribution of insulating varnish in complex winding gaps. Summary of the Invention

[0006] To this end, the present invention provides a vacuum varnishing device for motor windings and a varnishing process thereof, so as to overcome the problem of insufficient penetration depth of insulating varnish in complex winding gaps in the prior art.

[0007] To achieve the above object, the present invention provides a coating process for motor windings, comprising:

[0008] Step S1, obtaining winding structure parameters of the motor winding to be impregnated and dynamic viscosity data of the insulating varnish, wherein the winding structure parameters include winding gap density and winding capillary coefficient;

[0009] Step S2, determining initial paint dipping parameters according to the winding structure parameters and the dynamic viscosity data, wherein the initial paint dipping parameters include initial paint dipping pressure and paint dipping time;

[0010] Step S3, placing the motor winding vertically in the immersion tank along the axial direction and pre-baking it, allowing the motor winding to cool naturally after the pre-baking is completed, and when the motor winding cools to a preset temperature, vacuum evacuating the immersion tank;

[0011] Step S4, after the vacuum exhaust is completed, injecting insulating paint into the immersion tank, and performing pressure immersion varnishing on the motor winding according to the initial immersion varnishing parameters;

[0012] Step S5, real-time monitoring of the temperature data of the motor winding during the pressure varnish dipping process, determining the speed of the varnish dipping front according to the temperature data, and adjusting the current varnish dipping pressure according to the varnish dipping front speed and the winding gap density;

[0013] Step S6, determining a penetration depth characterizing value according to the temperature data, and correcting the current immersion pressure and the immersion time according to the penetration depth characterizing value and the immersion front travel speed;

[0014] Step S7, after the pressure dipping is completed, the pressure is unloaded and the paint back, paint dripping, secondary paint back, low temperature drying and high temperature curing are carried out in sequence to obtain the motor winding finished product that has completed the paint dipping process.

[0015] Furthermore, in step S2,

[0016] Determining the initial varnish dipping pressure according to the winding capillary coefficient and the dynamic viscosity data;

[0017] The varnish dipping time is determined according to the winding gap density and the initial varnish dipping pressure.

[0018] Furthermore, the temperature data includes first temperature data, second temperature data and third temperature data uniformly detected from the inner surface of the motor winding in sequence along the rising direction of the varnish liquid level.

[0019] Furthermore, the step S5 includes:

[0020] Step S51, calculating a first temperature change rate, a second temperature change rate, and a third temperature change rate based on the first temperature data, the second temperature data, and the third temperature data, respectively, and determining a position of a coating front of the insulating varnish in the axial direction of the motor winding based on the first temperature change rate, the second temperature change rate, and the third temperature change rate;

[0021] Step S52, calculating the speed of the paint dipping front according to the change of the paint dipping front position over time;

[0022] Step S53, determining the paint dipping pressure adjustment amount according to the paint dipping front travel speed;

[0023] Step S54 , correcting the paint dipping pressure adjustment amount according to the winding gap density to obtain a corrected paint dipping pressure adjustment amount, and adjusting the current paint dipping pressure with the corrected paint dipping pressure adjustment amount.

[0024] Furthermore, in step S51, when the first temperature change rate, the second temperature change rate, or the third temperature change rate satisfies or is greater than or equal to a temperature drop rate threshold, it is determined that the paint dipping front reaches the corresponding temperature sensor position.

[0025] Furthermore, the step S52 includes:

[0026] Step S521, recording the first moment, the second moment, and the third moment corresponding to when the paint dipping front reaches the positions of the first temperature sensor, the second temperature sensor, and the third temperature sensor respectively;

[0027] Step S522: Calculate a first immersion speed based on the time difference between the first moment and the second moment and the axial distance between the first temperature sensor and the second temperature sensor, and calculate a second immersion speed based on the time difference between the third moment and the second moment and the axial distance between the third temperature sensor and the second temperature sensor;

[0028] Step S523: Calculate the paint dipping front moving speed according to the first paint dipping speed and the second paint dipping speed.

[0029] Furthermore, in step S54,

[0030] When the winding gap density is greater than the winding gap density threshold, increasing the paint dipping pressure adjustment amount to obtain the corrected paint dipping pressure adjustment amount;

[0031] When the winding gap density is less than or equal to the winding gap density threshold, the value of the paint dipping pressure adjustment amount is maintained unchanged to obtain the corrected paint dipping pressure adjustment amount.

[0032] Furthermore, step S6 includes:

[0033] Step S61, calculating a first penetration depth characterizing value, a second penetration depth characterizing value, and a third penetration depth characterizing value according to the first temperature change rate, the second temperature change rate, and the third temperature change rate, respectively;

[0034] Step S62, when the pressure immersion reaches the immersion time, comparing the first penetration depth characterizing value, the second penetration depth characterizing value, and the third penetration depth characterizing value with a preset saturation threshold;

[0035] Step S63, determining whether each corresponding position has reached a capillary penetration saturation state;

[0036] Step S64, when there are locations that have not reached the capillary penetration saturation state, calculating an adjustment reference value according to the maximum value of the ratio of the penetration depth representation values ​​of all locations that have not reached the capillary penetration saturation state to the preset saturation threshold;

[0037] Step S65 , increasing the current immersion pressure and the immersion time according to the adjustment reference value and the immersion front speed.

[0038] Furthermore, in step S65,

[0039] The increase range of the current varnish dipping pressure is positively correlated with the adjustment reference value and the varnish dipping front travel speed;

[0040] The increase in the paint dipping time is positively correlated with the adjustment reference value and the speed of the paint dipping front.

[0041] Furthermore, the present invention also provides a vacuum impregnation device for motor windings, comprising:

[0042] An immersion mechanism, which is used to accommodate the motor windings and form a sealed cavity for vacuum exhaust and pressure dipping operations, including an immersion cylinder of a cylindrical pressure-resistant container;

[0043] A paint storage mechanism for storing insulating paint, connected to the immersion cylinder via a paint inlet pipe for injecting insulating paint into the immersion cylinder, and connected to the immersion cylinder via a paint return pipe for collecting returned paint after pressure dipping, wherein the paint storage tank comprises a cylindrical sealed container, and a stirring mechanism is provided inside the paint storage tank for maintaining the fluidity of the insulating paint;

[0044] A vacuum generating mechanism is connected to the top of the immersion cylinder through a vacuum pipe, and is used to vacuum the immersion cylinder to remove air from the winding gap;

[0045] A pressure injection mechanism, which is connected to the top of the immersion cylinder through a high-pressure pipeline, is used to inject gas into the immersion cylinder to pressurize and maintain the paint dipping pressure;

[0046] A temperature control mechanism is connected to the immersion cylinder and inputs dry hot air into the immersion cylinder through a heater and a fan to perform pre-baking and high-temperature curing operations;

[0047] A temperature sensor group, comprising three temperature sensors disposed on the inner surface of the motor winding, for real-time monitoring of temperature changes at different locations of the motor winding;

[0048] The control mechanism is connected to the immersion mechanism, the temperature control mechanism, the paint storage mechanism, the vacuum generating mechanism, the pressure injection mechanism and the temperature sensor group, and is used to receive the temperature sensor group signal, and to adjust the initial parameters of the immersion paint and the immersion paint pressure.

[0049] Compared with the existing technology, the beneficial effect of the present invention is that, by establishing a dynamic mapping mechanism between winding structure parameters and varnish dipping process parameters, combined with real-time closed-loop regulation of temperature feedback, the present invention significantly improves the control of the penetration process of insulating varnish in the motor winding, and solves the problem of insufficient penetration caused by parameter curing in traditional processes.

[0050] Furthermore, the present invention determines the initial varnish dipping parameters by collaborative analysis based on the winding gap density and capillary coefficient, so that the initial process conditions are accurately matched with the physical properties of the winding, avoiding insufficient penetration or waste of insulating varnish caused by blind setting.

[0051] Furthermore, the present invention monitors the winding temperature in real time and associates it with a paint immersion depth prediction model to dynamically adjust the paint immersion pressure and temperature, thereby overcoming the uncontrollable factor that the paint liquid viscosity changes with temperature and ensuring continuous optimization of the penetration process.

[0052] Furthermore, the present invention dynamically coordinates the temperature platform trigger mechanism with the paint immersion time, thereby shortening the ineffective paint immersion time while ensuring the minimum penetration depth, improving production efficiency and reducing energy consumption.

[0053] Furthermore, the present invention uses a multi-parameter collaborative adjustment mechanism to make the process adaptive to windings of different specifications, maintain the optimal penetration state without human intervention, and significantly reduce dependence on operating experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 This is a flow chart of a varnish dipping process for motor windings according to an embodiment of the present invention;

[0055] Figure 2 This is a flow chart of step S5 of the varnish dipping process for motor windings according to an embodiment of the present invention;

[0056] Figure 3 This is a flow chart of step S6 of the varnish dipping process for motor windings according to an embodiment of the present invention;

[0057] Figure 4 Schematic diagram of a paint dipping device for motor windings according to an embodiment of the present invention;

[0058] In the figure, 1-immersion tank; 2-paint storage tank; 21-paint supply pipe; 22-paint return pipe; 3-vacuum generating mechanism; 41-heater; 42-fan. DETAILED DESCRIPTION

[0059] In order to make the objects and advantages of the present invention more clearly understood, the present invention is further described below in conjunction with embodiments; it should be understood that the specific embodiments described herein are merely used to explain the present invention and are not intended to limit the present invention.

[0060] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention.

[0061] It should be noted that, in the description of the present invention, terms such as "up", "down", "left", "right", "inside", and "outside" indicating directions or positional relationships are based on the directions or positional relationships shown in the accompanying drawings. This is only for the convenience of description and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present invention.

[0062] Furthermore, it should be noted that, in the description of the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0063] See also Figure 4 As shown, it is a schematic diagram of a paint dipping device for motor windings according to an embodiment of the present invention; this embodiment provides a paint dipping device, comprising:

[0064] An immersion mechanism, which is used to accommodate the motor windings and form a sealed cavity for performing vacuum exhaust and pressure dipping operations, and includes an immersion cylinder 1 which is a cylindrical pressure-resistant container;

[0065] A paint storage mechanism for storing insulating paint, connected to the immersion tank 1 via a paint inlet pipe 21 for injecting insulating paint into the immersion tank 1, and connected to the immersion tank 1 via a paint return pipe 22 for collecting returned paint after pressure dipping, wherein the paint storage tank 2 comprises a cylindrical sealed container, and a stirring mechanism is provided inside the paint storage tank 2 to maintain the fluidity of the insulating paint;

[0066] A vacuum generating mechanism 3 is connected to the top of the immersion cylinder 1 through a vacuum pipe, and is used to vacuum the immersion cylinder to remove air from the winding gap;

[0067] A pressure injection mechanism, which is connected to the top of the immersion cylinder 1 through a high-pressure pipeline, is used to inject gas into the immersion cylinder 1 to pressurize and maintain the paint dipping pressure;

[0068] A temperature control mechanism is connected to the immersion tank and inputs dry hot air into the immersion tank 1 through a heater 41 and a fan 42 to perform pre-baking and high-temperature curing operations;

[0069] A temperature sensor group, which includes three temperature sensors arranged on the inner surface of the motor winding to monitor the temperature changes at different positions of the motor winding in real time;

[0070] The control mechanism is connected to the immersion mechanism, the temperature control mechanism, the paint storage mechanism, the vacuum generating mechanism 3, the pressure injection mechanism and the temperature sensor group, and is used to receive the temperature sensor group signal, and to adjust the initial parameters of the immersion paint and the immersion paint pressure.

[0071] Please continue reading Figure 1 As shown, it is a flow chart of the varnish dipping process for motor windings according to an embodiment of the present invention, including:

[0072] Step S1, obtaining winding structure parameters of the motor winding to be impregnated and dynamic viscosity data of the insulating varnish, wherein the winding structure parameters include winding gap density and winding capillary coefficient;

[0073] In a specific embodiment, the winding gap density of the motor winding is obtained by intercepting motor winding samples from the same batch, performing three-dimensional imaging using an industrial CT scanner, and using image processing software (VGStudioMAX) to measure the area ratio of the winding gap at at least five equidistant sections along the axial direction of the winding. The arithmetic average of the measured values ​​of the winding gap area ratio of each section is taken as the winding gap density, which is dimensionless and has a value range of 0 to 1.

[0074] In a specific embodiment, the capillary coefficient of the motor winding is obtained by cutting a typical winding section from the same batch of motor windings to prepare a standard winding sample with a diameter of 10 mm and a length of 50 mm (including a conductor, an insulation layer, and a gap structure);

[0075] Use acetone as the standard test liquid, fix the sample vertically on a bracket, ensure that the axis of the sample is vertical, and immerse the lower end of the sample in a container filled with acetone under constant temperature conditions to a depth of 1mm to 2mm to prevent the rising process of the liquid from being affected by other factors.

[0076] It is understood that acetone has a known viscosity and is a commonly used solvent with a low surface tension, making it suitable for capillary action testing.

[0077] Use a high-speed camera to record the process of the liquid rising in the winding gap. The camera should be placed perpendicular to the sample so that the change of the liquid rising height over time can be clearly recorded.

[0078] A small amount of fluorescent dye is added to acetone to facilitate observation of the rising height of the liquid without changing the surface tension and viscosity of the liquid.

[0079] Data on the time-varying liquid rise height is extracted from high-speed camera video. Generally, the relationship between the liquid rise height h and time t conforms to the Washburn equation. Because the winding structure is complex and not a single capillary tube but a porous medium, the winding sample can be treated as a porous medium and characterized by the capillary coefficient K.

[0080] Specifically, the capillary coefficient K is defined as: K = (γ × r × cosθ) / η0;

[0081] According to the Washburn equation, h 2 = (K / 2) × t;

[0082] Where γ is the surface tension of the standard test fluid, r is the capillary radius, θ is the contact angle, and η0 is the viscosity of the standard test fluid.

[0083] Through experimental data, we get h 2 The slope of the graph of the relationship between t and K is K / 2, so the capillary coefficient K is calculated in mm. 2 / s.

[0084] In a specific embodiment, the dynamic viscosity data of the insulating paint is obtained as follows: using a rotational viscometer to measure at a constant temperature of 25±0.5°C, selecting rotor No. 3 to test the dynamic viscosity value of the insulating paint at a speed of 12 rpm (unit: Pa·s), recording the torque value in the stable rotation state and converting it into a dynamic viscosity value, repeating the measurement three times and taking the arithmetic mean to obtain the dynamic viscosity data of the insulating paint.

[0085] The method for obtaining the winding gap density and winding capillary coefficient of the motor winding, as well as the dynamic viscosity data of the insulating paint is prior art. Those skilled in the art can adaptively replace the acquisition method and acquisition equipment while achieving the same effect, which will not be repeated here.

[0086] It can be understood that the winding gap density reflects the tightness of the insulating material between the conductors within the motor winding and the distribution characteristics of the gaps. Its value directly determines the complexity of the insulating paint's penetration path and flow resistance within the winding. The winding capillary coefficient characterizes the winding material's capillary adsorption capacity for the insulating paint. This parameter is determined by the conductor surface characteristics, the pore structure of the insulating material, and the surface tension of the liquid. It is used to predict the spontaneous penetration rate of the insulating paint in the microscopic pores. The insulating paint dynamic viscosity parameter reflects the flow properties of the paint liquid at a specific temperature and is a key physical indicator for calculating the pressure and penetration time required for varnish dipping. The synergistic effect of these three parameters jointly determines the kinetic behavior of the insulating paint's penetration within the winding: the gap density affects the geometric characteristics of the macroscopic flow channel, the capillary coefficient dominates the infiltration efficiency of the microscopic pores, and the dynamic viscosity determines the paint liquid's ability to overcome flow resistance. The combination of these three parameters provides the physical basis for precisely controlling the varnish dipping pressure, temperature, and time parameters, ensuring that the insulating paint can achieve complete coverage from the winding surface to the deep conductor.

[0087] Step S2, determining initial paint dipping parameters according to the winding structure parameters and the dynamic viscosity data, wherein the initial paint dipping parameters include initial paint dipping pressure and paint dipping time;

[0088] Specifically, in step S2, the initial paint dipping pressure is determined according to the winding capillary coefficient and the dynamic viscosity data; and the paint dipping time is determined according to the winding gap density and the initial paint dipping pressure.

[0089] In a specific embodiment, the calculation formula of the initial immersion pressure is:

[0090] ,

[0091] Where m is the initial immersion pressure coefficient, unit is (mm / s) 2 ;

[0092] Preferably, m is 10 (mm / s) 2 ~14 (mm / s) 2 , which is determined through historical experiments and will not be repeated here; η is the dynamic viscosity data, the unit is Pa·s; K is the winding capillary coefficient.

[0093] It can be understood that the winding capillary coefficient K reflects the permeability of the winding gap, the dynamic viscosity η affects the flow resistance of the paint liquid, and high pressure can accelerate the paint liquid to fill high-density gaps, but excessive pressure should be avoided to prevent winding deformation.

[0094] The calculation formula for the immersion time is specifically:

[0095] ,

[0096] Wherein, T0 is the reference immersion time in hours (h), preferably, 2h, ρ is the winding gap density, c is the time proportional coefficient, in h·Mpa, preferably, c is 0.5h·Mpa.

[0097] It can be understood that the higher the winding gap density ρ, the longer the paint immersion time is required to ensure that the paint liquid fully fills the gap. At the same time, since high pressure can accelerate the paint liquid to fill high-density gaps, the paint immersion time can be appropriately shortened.

[0098] Step S3, placing the motor winding vertically in the immersion tank 1 along the axial direction and pre-baking it, allowing the motor winding to cool naturally after the pre-baking is completed, and when the motor winding cools to a preset temperature, vacuum evacuating the immersion tank 1;

[0099] In a specific embodiment, the workpiece is pre-baked at a temperature of 80°C to 110°C for 2 to 3 hours. After pre-baking, the motor windings are cooled to a preset temperature of 40°C, and then the immersion cylinder 1 is vacuum-exhausted. After vacuum exhaust, the vacuum level is less than or equal to 100 Pa, and the vacuum is maintained for 3 to 4 hours. The above-described pre-baking, cooling, and vacuuming procedures are conventional techniques and will not be further described.

[0100] Step S4, after the vacuum exhaust is completed, insulating paint is injected into the immersion tank 1, and the motor winding is pressure-impregnated according to the initial parameters of the immersion paint;

[0101] In a specific embodiment, after the vacuum period is complete, the paint is applied, and the temperature of the insulating paint is 25°C. After the insulating paint is applied and the foam disappears, the liquid level of the insulating paint is required to be 100 mm above the highest part of the workpiece surface. The motor windings are then pressure dipped at the initial dipping pressure and dipping time.

[0102] It is understandable that, while meeting the process requirements, a large temperature difference is selected between the insulating paint temperature and the cooling temperature of the motor winding, so as to determine the varnish dipping process through the subsequent temperature change of the motor winding.

[0103] Step S5, real-time monitoring of the temperature data of the motor winding during the pressure varnish dipping process, determining the speed of the varnish dipping front according to the temperature data, and adjusting the current varnish dipping pressure according to the varnish dipping front speed and the winding gap density;

[0104] Specifically, the temperature data includes first temperature data, second temperature data and third temperature data uniformly detected from the inner surface of the motor winding in sequence along the rising direction of the varnish liquid level.

[0105] Please continue reading Figure 2 As shown, it is a flow chart of step S5 of the paint dipping process for motor windings according to an embodiment of the present invention. Specifically, step S5 includes:

[0106] Step S51, calculating a first temperature change rate, a second temperature change rate, and a third temperature change rate based on the first temperature data, the second temperature data, and the third temperature data, respectively, and determining a position of a coating front of the insulating varnish in the axial direction of the motor winding based on the first temperature change rate, the second temperature change rate, and the third temperature change rate;

[0107] Specifically, in step S51, when the first temperature change rate, the second temperature change rate, or the third temperature change rate satisfies or is greater than or equal to a temperature drop rate threshold, it is determined that the paint dipping front reaches the corresponding temperature sensor position.

[0108] In a specific embodiment, temperature data is collected in real time by a first temperature sensor (at the top of the winding), a second temperature sensor (at the middle of the winding), and a third temperature sensor (at the bottom of the winding).

[0109] Calculate the temperature change rate every 10 seconds. Specifically,

[0110] First temperature change rate = (current first temperature - first temperature 10 seconds ago) / 10, unit is ℃ / s.

[0111] The second and third temperature change rates are calculated similarly.

[0112] The temperature drop rate threshold is set to 0.4°C / s. That is, if the temperature change rate of any sensor is ≥ 0.4°C / s, it is determined that the paint immersion front has reached the sensor position.

[0113] Step S52, calculating the speed of the paint dipping front according to the change of the paint dipping front position over time;

[0114] Specifically, step S52 includes:

[0115] Step S521, recording the first moment, the second moment, and the third moment corresponding to when the paint dipping front reaches the positions of the first temperature sensor, the second temperature sensor, and the third temperature sensor respectively;

[0116] Step S522: Calculate a first immersion speed based on the time difference between the first moment and the second moment and the axial distance between the first temperature sensor and the second temperature sensor, and calculate a second immersion speed based on the time difference between the third moment and the second moment and the axial distance between the third temperature sensor and the second temperature sensor;

[0117] Step S523: Calculate the paint dipping front moving speed according to the first paint dipping speed and the second paint dipping speed.

[0118] In a specific embodiment, the moment when the paint front reaches three sensors is recorded, specifically,

[0119] The first moment (T1) is when the paint dipping front reaches the first temperature sensor at the top;

[0120] The second moment (T2) is when the paint dipping front reaches the second temperature sensor in the middle;

[0121] The third moment (T3) is when the paint dipping front reaches the third temperature sensor at the bottom;

[0122] The calculation speed can be obtained as follows:

[0123] First dipping speed = (distance between the second temperature sensor and the first temperature sensor) / (T2-T1);

[0124] Second dipping speed = (distance between the third temperature sensor and the second temperature sensor) / (T3-T2);

[0125] It can be obtained that the speed of the paint front = (first paint speed + second paint speed) / 2.

[0126] Step S53, determining the paint dipping pressure adjustment amount according to the paint dipping front travel speed;

[0127] In a specific embodiment, the target speed range is set to [2 mm / s, 3 mm / s];

[0128] If the measured speed is less than 2 mm / s, the immersion pressure adjustment amount = 0.1 MPa × (2 mm / s - measured speed);

[0129] If the measured speed is greater than 3 mm / s, the paint immersion pressure adjustment amount = -0.05 MPa × (measured speed - 3 mm / s).

[0130] Step S54 , correcting the paint dipping pressure adjustment amount according to the winding gap density to obtain a corrected paint dipping pressure adjustment amount, and adjusting the current paint dipping pressure with the corrected paint dipping pressure adjustment amount.

[0131] Specifically, in step S54, when the winding gap density is greater than the winding gap density threshold, the paint immersion pressure adjustment amount is increased to obtain the corrected paint immersion pressure adjustment amount; when the winding gap density is less than or equal to the winding gap density threshold, the value of the paint immersion pressure adjustment amount is maintained unchanged to obtain the corrected paint immersion pressure adjustment amount.

[0132] In a specific embodiment, the winding gap density threshold is set to 0.2. If the measured winding gap density ρ>0.2, then the corrected immersion pressure adjustment amount = immersion pressure adjustment amount × 1.5;

[0133] If the measured winding gap density ρ≤0.2, then the correction varnish dipping pressure adjustment amount = varnish dipping pressure adjustment amount;

[0134] The final adjustment of the varnish dipping pressure is to increase the corrected varnish dipping pressure adjustment amount.

[0135] It's understandable that the core principle of this step (step S5) is the coupling of heat exchange and capillary penetration. After pre-baking, the winding temperature (approximately 40°C) is much higher than the insulating varnish temperature (approximately 25°C). When the varnish front reaches a certain location, rapid heat exchange occurs between the low-temperature insulating varnish and the high-temperature winding, causing a sudden drop in temperature at that location (temperature drop rate ≥ 0.4°C / s). After the front passes, capillary action causes the insulating varnish to continue penetrating deeper into the microgaps, but the heat exchange intensity weakens, and the temperature drop rate gradually slows. A slow varnishing speed (<2 mm / s) indicates insufficient driving force, requiring increased pressure to improve varnish fluidity. A fast varnishing speed (>3 mm / s) can easily lead to trapped bubbles, requiring reduced pressure. The winding gap density correction effect is as follows: a high gap density (ρ > 0.2) indicates a larger gap between the windings, resulting in less resistance to varnish flow, requiring increased pressure adjustment for a faster response. A low gap density (ρ ≤ 0.2) indicates narrow microgaps, requiring careful adjustment to avoid excessive pressure and winding deformation.

[0136] The present invention uses dynamic closed-loop control to locate the paint dipping front in real time using the temperature change rate, and dynamically adjusts the pressure in combination with speed feedback, effectively preventing uneven paint film (too fast speed) or insufficient penetration (too slow speed), improving the reliability of the insulation layer, and avoiding the blind reliance of traditional processes on fixed parameters. The winding gap density is introduced to correct the pressure adjustment amount, making the control strategy adaptive to different winding structures (such as high-density small motors and low-density large motors).

[0137] Step S6, determining a penetration depth characterizing value according to the temperature data, and correcting the current immersion pressure and the immersion time according to the penetration depth characterizing value and the immersion front travel speed;

[0138] Please continue reading Figure 3As shown, it is a flow chart of step S6 of the paint dipping process for motor windings according to an embodiment of the present invention. Specifically, step S6 includes:

[0139] Step S61, calculating a first penetration depth characterizing value, a second penetration depth characterizing value, and a third penetration depth characterizing value according to the first temperature change rate, the second temperature change rate, and the third temperature change rate, respectively;

[0140] In a specific embodiment, the temperature change rate data (in °C / s) of the first, second, and third temperature sensors are acquired in real time, and the corresponding penetration depth representation value is calculated. The calculation formula of the penetration depth representation value is specifically:

[0141] ,

[0142] Where D is the penetration depth characterization value, unit is ℃ / s 2 ; k is the penetration depth coefficient, ranging from 2 to 3, preferably, k is 2.5; dT / dt 2 is the acceleration of the temperature change rate, in °C / s 2 .

[0143] It can be understood that for the first temperature change rate, the second temperature change rate and the third temperature change rate, there are respectively a first penetration depth characterization value D1, a second penetration depth characterization value D2 and a third penetration depth characterization value D3.

[0144] Step S62, when the pressure immersion reaches the immersion time, comparing the first penetration depth characterizing value, the second penetration depth characterizing value, and the third penetration depth characterizing value with a preset saturation threshold;

[0145] Step S63, determining whether each corresponding position has reached a capillary penetration saturation state;

[0146] In a specific embodiment, when the pressure immersion reaches the immersion time, D1, D2, and D3 are compared with the preset saturation threshold, wherein the preset saturation threshold is 0.1°C / s. 2 If the penetration depth representation value is less than the preset saturation threshold, it is determined that the position is not penetrated and saturated; otherwise, it is determined that the position is penetrated and saturated.

[0147] Step S64 : when there are locations that have not reached the capillary penetration saturation state, an adjustment reference value is calculated based on the maximum value of the ratio of the penetration depth characterization values ​​of all locations that have not reached the capillary penetration saturation state to the preset saturation threshold.

[0148] In a specific embodiment, the difference ratio of all unsaturated locations in a zone is specifically:

[0149] ,

[0150] Among them, R is the difference ratio; D s The preset saturation threshold is 0.1℃ / s 2 .

[0151] Take the maximum value R max as the adjustment reference value.

[0152] Step S65 , increasing the current immersion pressure and the immersion time according to the adjustment reference value and the immersion front speed.

[0153] Specifically, in step S65, the increase in the current paint immersion pressure is positively correlated with the adjustment reference value and the paint immersion front speed; the increase in the paint immersion time is positively correlated with the adjustment reference value and the paint immersion front speed.

[0154] In a specific embodiment, the calculation formulas for the increase in the immersion pressure and the increase in the immersion time are as follows:

[0155] ;

[0156] Among them, △P is the increase in immersion pressure, the unit is MPa, a is the immersion pressure adjustment coefficient, the unit is MPa·s / mm, preferably, 0.05 MPa·s / mm; v is the speed of the immersion front, the unit is mm / s.

[0157] ;

[0158] Among them, △T is the increase in immersion time, unit is s, b is the adjustment coefficient of immersion time, unit is s 2 / mm, preferably, 70s 2 / mm; v is the speed of the paint dipping front, the unit is mm / s.

[0159] It's understandable that the rate of temperature change is correlated with the depth of capillary penetration. When insulating varnish penetrates through capillary action, it absorbs heat from the winding, causing a local temperature drop. The deeper the penetration, the greater the rate of temperature change due to the increased heat exchange area. Through the quantitative relationship established through calibration experiments, temperature data is converted into a quantifiable representation of the penetration depth. A control logic for the difference ratio and adjustment baseline value is established to reflect the degree of penetration loss at the weakest location, ensuring that adjustments cover the worst-case operating conditions. At the same time, combined with the dynamic adjustment parameter for the paint front speed, a slow paint front speed indicates high penetration resistance, requiring a significant increase in pressure to accelerate paint flow. If the paint front speed is fast but the difference ratio is high (locally insufficient penetration), the time must be extended to ensure deep saturation. Simply increasing pressure may cause the paint to flow too quickly and overflow the gap. Simultaneously extending the time balances penetration quality and efficiency.

[0160] Step S7, after the pressure dipping is completed, the pressure is unloaded and the paint back, paint dripping, secondary paint back, low temperature drying and high temperature curing are carried out in sequence to obtain the motor winding finished product that has completed the paint dipping process.

[0161] It is understandable that the processes of the above steps are prior art and will not be described in detail here.

[0162] Thus far, the technical solutions of the present invention have been described in conjunction with the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art may make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will fall within the scope of protection of the present invention.

Claims

1. A coating process for motor windings, characterized in that: include: Step S1, obtaining winding structure parameters of the motor winding to be impregnated and dynamic viscosity data of the insulating varnish, wherein the winding structure parameters include winding gap density and winding capillary coefficient; Step S2, determining initial paint dipping parameters according to the winding structure parameters and the dynamic viscosity data, wherein the initial paint dipping parameters include initial paint dipping pressure and paint dipping time; Step S3, placing the motor winding vertically in the immersion tank along the axial direction and pre-baking it, allowing the motor winding to cool naturally after the pre-baking is completed, and when the motor winding cools to a preset temperature, vacuum evacuating the immersion tank; Step S4, after the vacuum exhaust is completed, injecting insulating paint into the immersion tank, and performing pressure immersion varnishing on the motor winding according to the initial immersion varnishing parameters; Step S5: monitoring the temperature data of the motor winding in the pressure varnishing process in real time, determining the speed of the varnishing front of the insulating varnish according to the temperature data, and adjusting the current varnishing pressure according to the speed of the varnishing front and the winding gap density, wherein the temperature data includes first temperature data, second temperature data, and third temperature data uniformly detected from the inner surface of the motor winding in the direction of rising varnishing liquid level; Step S5 includes: Step S51, calculating a first temperature change rate, a second temperature change rate, and a third temperature change rate based on the first temperature data, the second temperature data, and the third temperature data, respectively, and determining a position of a coating front of the insulating varnish in the axial direction of the motor winding based on the first temperature change rate, the second temperature change rate, and the third temperature change rate; Step S52, calculating the speed of the paint dipping front according to the change of the paint dipping front position over time; Step S53, determining the paint dipping pressure adjustment amount according to the paint dipping front travel speed; Step S54, correcting the paint dipping pressure adjustment amount according to the winding gap density to obtain a corrected paint dipping pressure adjustment amount, and adjusting the current paint dipping pressure with the corrected paint dipping pressure adjustment amount; Step S6, determining a penetration depth characterizing value according to the temperature data, and correcting the current immersion pressure and the immersion time according to the penetration depth characterizing value and the immersion front travel speed; Step S7, after the pressure dipping is completed, the pressure is unloaded and the paint back, paint dripping, secondary paint back, low temperature drying and high temperature curing are carried out in sequence to obtain the motor winding finished product that has completed the paint dipping process.

2. The varnishing process for motor windings according to claim 1, characterized in that: In the step S2, Determining the initial varnish dipping pressure according to the winding capillary coefficient and the dynamic viscosity data; The varnish dipping time is determined according to the winding gap density and the initial varnish dipping pressure.

3. The varnishing process for motor windings according to claim 1, characterized in that: In step S51 , when the first temperature change rate, the second temperature change rate, or the third temperature change rate satisfies or is greater than or equal to a temperature drop rate threshold, it is determined that the paint dipping front reaches the corresponding temperature sensor position.

4. The varnishing process for motor windings according to claim 3, characterized in that: The step S52 includes: Step S521, recording the first moment, the second moment, and the third moment corresponding to when the paint dipping front reaches the positions of the first temperature sensor, the second temperature sensor, and the third temperature sensor, respectively, wherein the first temperature sensor is located at the top of the winding, the second temperature sensor is located in the middle of the winding, and the third temperature sensor is located at the bottom of the winding; Step S522: Calculate a first immersion speed based on the time difference between the first moment and the second moment and the axial distance between the first temperature sensor and the second temperature sensor, and calculate a second immersion speed based on the time difference between the third moment and the second moment and the axial distance between the third temperature sensor and the second temperature sensor; Step S523: Calculate the paint dipping front moving speed according to the first paint dipping speed and the second paint dipping speed.

5. The varnish dipping process for motor windings according to claim 4, characterized in that: In the step S54, When the winding gap density is greater than the winding gap density threshold, increasing the paint dipping pressure adjustment amount to obtain the corrected paint dipping pressure adjustment amount; When the winding gap density is less than or equal to the winding gap density threshold, the value of the paint dipping pressure adjustment amount is maintained unchanged to obtain the corrected paint dipping pressure adjustment amount.

6. The varnish dipping process for motor windings according to claim 5, characterized in that: The step S6 comprises: Step S61, calculating a first penetration depth characterizing value, a second penetration depth characterizing value, and a third penetration depth characterizing value according to the first temperature change rate, the second temperature change rate, and the third temperature change rate, respectively; Step S62, when the pressure immersion reaches the immersion time, comparing the first penetration depth characterizing value, the second penetration depth characterizing value, and the third penetration depth characterizing value with a preset saturation threshold; Step S63, determining whether each corresponding position has reached a capillary penetration saturation state; Step S64, when there are locations that have not reached the capillary penetration saturation state, calculating an adjustment reference value according to the maximum value of the ratio of the penetration depth representation values ​​of all locations that have not reached the capillary penetration saturation state to the preset saturation threshold; Step S65 , increasing the current immersion pressure and the immersion time according to the adjustment reference value and the immersion front speed.

7. The varnish dipping process for motor windings according to claim 6, characterized in that: In the step S65, The increase range of the current varnish dipping pressure is positively correlated with the adjustment reference value and the varnish dipping front travel speed; The increase in the paint dipping time is positively correlated with the adjustment reference value and the speed of the paint dipping front.

8. A vacuum impregnation equipment for motor windings, which is applied to the impregnation process for motor windings according to any one of claims 1 to 7, characterized in that: include: An immersion mechanism, which is used to accommodate the motor windings and form a sealed cavity for vacuum exhaust and pressure dipping operations, including an immersion cylinder of a cylindrical pressure-resistant container; A paint storage mechanism for storing insulating paint, connected to the immersion cylinder via a paint inlet pipe for injecting insulating paint into the immersion cylinder, and connected to the immersion cylinder via a paint return pipe for collecting returned paint after pressure dipping, wherein the paint storage tank comprises a cylindrical sealed container, and a stirring mechanism is provided inside the paint storage tank for maintaining the fluidity of the insulating paint; A vacuum generating mechanism is connected to the top of the immersion cylinder through a vacuum pipe, and is used to vacuum the immersion cylinder to remove air from the winding gap; A pressure injection mechanism, which is connected to the top of the immersion cylinder through a high-pressure pipeline, is used to inject gas into the immersion cylinder to pressurize and maintain the paint dipping pressure; A temperature control mechanism is connected to the immersion cylinder and inputs dry hot air into the immersion cylinder through a heater and a fan to perform pre-baking and high-temperature curing operations; A temperature sensor group, which includes three temperature sensors arranged on the inner surface of the motor winding to monitor the temperature changes at different positions of the motor winding in real time; The control mechanism is connected to the immersion mechanism, the temperature control mechanism, the paint storage mechanism, the vacuum generating mechanism, the pressure injection mechanism and the temperature sensor group, and is used to receive the temperature sensor group signal, and to adjust the initial parameters of the immersion paint and the immersion paint pressure.

Images