Motor iron core inter-sheet pressure monitoring structure and testing method

Abstract

The invention discloses a motor iron core inter-sheet pressure monitoring structure and a testing method, the monitoring structure comprises at least three pressure sensors, two punching sheets in a motor iron core are used as a first punching sheet and a second punching sheet for testing, and the first punching sheet and the second punching sheet are fixedly connected along the thickness direction; the second punching sheet is provided with a plurality of arrangement grooves, the pressure sensors are fixed in the arrangement grooves respectively, and the tops of the pressure sensors are flush with the outer surface of the second punching sheet. According to the motor iron core inter-sheet pressure monitoring structure, the technical problem that in the prior art, iron cores of different topological structures cannot use the same monitoring module, so that cost is high is solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of generator manufacturing, and in particular relates to a pressure monitoring structure and a testing method between motor core sheets. Background Art

[0002] Electric motors are rotating machines, and their core components, the rotor or stator, need to maintain a certain pressure during use to keep the stator or rotor compact during rotation and reduce mechanical vibration. Core lamination is a key process in motor manufacturing, and inter-lamina pressure is an important control indicator for the core. It will directly affect the insulation state and iron loss level of the laminations, and thus directly affect the performance of the entire machine. The inter-lamina pressure cannot be too high, as excessive pressure will damage the insulation layer of the rotor or stator laminations and cause a sharp increase in iron loss. Ideally, the pressure between the laminations is uniform and the pressure level is appropriate. Common core laminations have an annular structure, including an inner lamination circle, an outer lamination circle, and multiple ventilation holes arranged between the inner and outer lamination circles. At present, there are two main methods for testing the pressure between core laminations: (1) Indirect method: collect the compression rate data of the core under different stacking pressures, draw a curve of the relationship between the two, measure the residual compression of the core after stacking, reversely calculate the core stacking pressure based on the curve, and then convert it into inter-lamina pressure based on the area; (2) Direct method: bury a force sensor inside the rotor core or at the connection interface of the fastening structure, collect data in real time and transmit it to the computer, and use monitoring software to read the pressure data.

[0003] Existing technologies that use indirect methods to measure inter-lamellar pressure, such as a method for manufacturing a motor stator core disclosed in Chinese invention patent application publication number CN107370303A, detect the actual compression of the stator core under different stacking pressures, draw a stacking pressure-compression curve, and use the core compression to infer the stacking pressure, thereby controlling the pressure between the core laminations. This patent converts the average inter-lamellar pressure, and it is impossible to understand the specific pressure distribution. In addition, the compression rate measurement under different stacking pressures is carried out using a hydraulic press in the free stacking state of the core. After the core is stacked, the actual inter-lamellar pressure is determined by the combined effects of the pressure ring holding structure, the core interference fit, and the fastening connection structure (welding / bolts / rivets, etc.). The core deformation varies under different pressure holding methods, and the measurement results differ from the actual application level of the core. At the same time, there are circumferential non-uniformity and manual measurement errors in the stacking height measurement. The error is even greater than the deformation of the core itself. The measurement accuracy is limited and the measurement process is cumbersome. Existing technologies that use direct methods to measure inter-lamina pressure, such as the one disclosed in Chinese Patent Authorization Announcement No. CN206756345U, describe a pressure monitoring structure for generator stator core lamina. This structure assembles sector-shaped pressure detection plates into an annular detection module, which is placed in the core. Data is transmitted to a monitoring computer via an acquisition system, enabling real-time monitoring of inter-lamina pressure. The sector-shaped pressure monitoring plates in this patent must avoid screws, rivets, magnets, or bars in the core, resulting in the inability to use the same set of monitoring modules for cores with different topological structures. Furthermore, the monitoring accuracy of the detection module is related to the number of rings in the annular monitoring module and the number of rings within each ring. Improving measurement accuracy requires a significant cost increase. Existing technologies that use direct methods to measure inter-lamellar pressure, such as the stator structure and stator measurement point arrangement method disclosed in Chinese Patent Application Publication No. CN114301193A, and the stator core compression fault detection device, detection method, generator set monitoring system, and computer-readable storage medium disclosed in Chinese Patent Application Publication No. CN114301193A, all propose placing a sensor between the core and the locking member and determining the core compression state based on pressure changes in the sensor. However, these methods are unsuitable for cores that are not screw-fastened. Furthermore, the pressure directly measured by the sensor is the pressure between the screw and the punching sheet, and cannot determine the inter-lamellar pressure of the punching sheet. Summary of the Invention

[0004] In response to the current technical problems, the present invention aims to provide a pressure monitoring structure and testing method between motor core plates. The monitoring structure can solve the technical problem in the prior art that cores with different topological structures cannot use the same set of monitoring modules, resulting in high costs.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A pressure monitoring structure between motor core sheets has the following structural features: it includes at least three pressure sensors, uses two punching sheets in the motor core as the first punching sheet and the second punching sheet for testing, and the first punching sheet and the second punching sheet are fixedly connected along the thickness direction; the second punching sheet is provided with multiple arrangement grooves, and the pressure sensors are respectively detachably fixed in the arrangement grooves, and the top of the pressure sensor is flush with the outer surface of the second punching sheet.

[0007] The pressure sensor can be fixed in the arrangement slot by bonding, or it can be adjusted by using a precision gap sheet so that it is in the same plane as the outer surface of the second punching sheet. By directly setting the pressure sensor inside the punching sheet of the motor core, the pressure between the sheets in different areas of the punching sheet can be directly measured. In addition, when the pressure sensor measures the internal pressure of the motor core punching sheet, it is not affected by the core fastening method. The pressure monitoring structure between the motor core sheets of the present application is applicable to both the stator core and the rotor core. It is directly made by cutting two punching sheets in the existing motor core, and the number of pressure sensors can be increased or decreased as needed. After the monitoring is completed, the pressure sensor can be recycled and reused, so that the pressure sensor can be flexibly used on the motor core punching sheets of different topological structures, with flexible reorganization, reduced cost, and improved measurement efficiency. The pressure monitoring structure between the motor core sheets of the present application can use a small-range pressure sensor to measure high-voltage motor core products by dividing the pressure at the measuring point, with high sensitivity and strong range adaptability.

[0008] Preferably, the plurality of arrangement grooves are evenly distributed on the second punching sheet, and a pressure sensor is provided in each arrangement groove.

[0009] Preferably, the plurality of arrangement slots are arranged in a ring on the second punching plate. When the actual application does not focus on the pressure distribution between the core plates but focuses on the pressure between the plates, the pressure sensor can be arranged in one of the inner ring area, the middle ring area and the outer ring area of ​​the second punching plate.

[0010] Preferably, the plurality of arrangement slots are respectively arranged around the inner circle of the second punch, the ventilation hole, and the outer circle of the punch. The arrangement slots arranged around the inner circle of the punch are located in the inner ring area of ​​the second punch, the arrangement slots arranged around the ventilation hole are located in the middle ring area of ​​the second punch, and the arrangement slots arranged around the outer circle of the punch are located in the outer ring area of ​​the second punch. The shapes of the punches of different motors vary, but all have an inner circle of the punch, ventilation holes, and an outer circle of the punch. The more pressure sensors there are, the more accurate the measurement.

[0011] In order to facilitate the wiring of the pressure sensor, preferably, the arrangement grooves located around the inner circle of the punch are connected to the ventilation holes or connected to the side wall where the inner circle of the punch is located, the arrangement grooves located around the ventilation holes are connected to the ventilation holes, and the arrangement grooves located around the outer circle of the punch are connected to the side wall where the outer circle of the punch is located.

[0012] Specifically, the motor core is a rotor core, and the second punching sheet is provided with multiple groups of magnetic steel slots, with the arrangement slots located around the outer circumference of the punching sheet being arranged between two adjacent groups of magnetic steel slots. The rotor core punching sheet is provided with multiple groups of magnetic steel slots depending on the number of stages, and the arrangement slots around the outer circumference of the punching sheet can be arranged based on the distribution characteristics of the magnetic steel slots.

[0013] Specifically, the arrangement groove is a through hole along the thickness direction of the second punching sheet, and the pressure sensor adopts a thin film pressure sensor, the thickness of which is less than or equal to the thickness of the second punching sheet. The thin film pressure sensor can adopt piezoresistive, piezoelectric or other types.

[0014] Based on the same inventive concept, the present invention also provides a method for testing pressure between motor core laminations, which uses the above-mentioned pressure testing structure between motor core laminations, including the following steps:

[0015] Step S1: Assemble the motor core according to the assembly sequence, and place the motor core inter-lamina pressure test structure between the laminations of the motor core;

[0016] Step S2: applying different and gradually increasing stacking forces to the motor core, recording the pressure data of each pressure sensor under each stacking force, summing the pressure data under each stacking force, and drawing a relationship diagram between the stacking force and the sum of the pressure data;

[0017] Step S3: Adjust the stacking force to the working pressure of the motor core, and tighten the motor core with fasteners under this pressure. Then remove the stacking force, record the sum of the pressure data of each pressure sensor at this time, and derive the stacking force corresponding to the sum of the pressure data in the relationship diagram in step S2.

[0018] The present invention relates to a method for testing the pressure between motor core laminations. By placing a pressure sensor in the arrangement slot of the second punching lamination, when the second punching lamination is subjected to a large pressure, only a small portion of the pressure is distributed to the sensor, and the vast majority is absorbed by the second punching lamination. In step S2, the pressure distributed by the pressure sensor under a known stacking pressure is obtained, and a relationship diagram of the stacking pressure and the sum of the measured pressures is plotted. In step S3, a round nut can be used as the fastener for the rotor core. After the stacking pressure is withdrawn, the stacking pressure under the pressure can be obtained by matching the measured pressure to the relationship diagram in step S2. This stacking pressure is the inter-lamination pressure of the motor core.

[0019] Specifically, in step S2, a polynomial is used to fit the stack pressure and the sum of the pressure data from each pressure sensor, or a relationship curve is drawn between the stack pressure and the sum of the pressure data from each pressure sensor. When using a polynomial for fitting, the higher the order of the polynomial, the higher the fitting accuracy. For piezoresistive thin film pressure sensors, a fourth-order polynomial or less is generally sufficient. If a polynomial fitting is used, in step S3, the pressures measured by each pressure sensor are directly summed and substituted into the polynomial to obtain the corresponding stack pressure. If a relationship curve is drawn, the pressures measured by each pressure sensor are summed and mapped to the relationship curve to obtain the corresponding stack pressure.

[0020] Preferably, step S4 and step S5 are also included. Step S4: mark the data of each pressure sensor in step S3 at the position corresponding to the second punching sheet to obtain a pressure distribution diagram, and compare the pressure data of each pressure sensor with the average value of the pressure data of each pressure sensor to determine the tightness of each area of ​​the second punching sheet; step S5: after the test is completed, disassemble each pressure sensor for reuse.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] 1. The pressure monitoring structure and testing method between the machine core sheets of the present application sets each pressure sensor inside the punching sheet of the motor core, which can directly measure the pressure between the sheets in different areas of the punching sheet, and when the pressure sensor measures the internal pressure of the motor core punching sheet, it is not affected by the core fastening method.

[0023] 2. The pressure monitoring structure and testing method between machine core sheets of the present application are applicable to both stator cores and rotor cores. They are directly produced by cutting two punching sheets in the existing motor core, and the number of pressure sensors can be increased or decreased according to needs. After the monitoring is completed, the pressure sensors can be recycled and reused, so that the pressure sensors can be flexibly used on motor core punching sheets with different topological structures, with flexible reorganization, reduced costs, and improved measurement efficiency.

[0024] 3. The pressure monitoring structure and testing method between the core sheets of the present application can measure the high-voltage motor core products with a small-range pressure sensor by dividing the pressure at the measuring point, with high sensitivity and strong range adaptability. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic diagram of the pressure monitoring structure between the core sheets of the machine according to the present invention;

[0026] Figure 2 yes Figure 1 BB cross-sectional structure diagram in;

[0027] Figure 3 yes Figure 1 Schematic diagram of the three-dimensional structure;

[0028] Figure 4 yes Figure 1 Schematic diagram of the circuit connection of the pressure sensor;

[0029] Figure 5 The figure is a schematic diagram of the connection structure of the motor core when the pressure test method between the core sheets of the motor is used for testing.

[0030] In the figure

[0031] 1-rotating shaft; 2-rotor pressure ring; 3-motor core; 4-round nut; 5-pressure conversion module; 6-data acquisition module; 7-pressure sensor; 8-layout slot; 9-first punching plate; 10-second punching plate; 1001-inner circle of punching plate; 1002-ventilation hole; 1003-outer circle of punching plate; 1004-magnetic steel slot. DETAILED DESCRIPTION

[0032] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments. It should be noted that the embodiments and features of the embodiments may be combined unless they conflict. For ease of description, the words "upper," "lower," "left," and "right" appear below merely to indicate the directions of upper, lower, left, and right in the accompanying drawings and do not limit the structure.

[0033] like Figure 1 and Figure 2 As shown, the pressure monitoring structure between the core sheets provided by this embodiment includes eighteen pressure sensors 7, which are piezoresistive thin film sensors with a thickness of 0.35 mm. Figure 4 As shown, the eighteen pressure sensors 7 are all connected to the pressure conversion module 5, and the pressure conversion module 5 is connected to the data acquisition module 6. The pressure sensors 7, the pressure conversion module 5 and the data acquisition module 6 are supporting products. Two punching sheets in the motor core 3 are used as the first punching sheet 9 and the second punching sheet 10 for testing. The first punching sheet 9 and the second punching sheet 10 are fixedly connected along the thickness direction by bonding. The motor core 3 of this embodiment is the rotor core, and the thickness of the first punching sheet 9 and the second punching sheet 10 are both 0.35 mm. Eighteen arrangement slots 8 are provided on the second punching sheet 10, and the arrangement slots 8 are through holes along the thickness direction of the second punching sheet 10. The pressure sensors 7 are fixed in the arrangement slots 8 by bonding, and the top of the pressure sensor 10 is flush with the outer surface of the second punching sheet 10. The second punching sheet 10 is an annular structure. Six ventilation holes 1002 are provided between the inner circle 1001 and the outer circle 1003 of the second punching sheet 10, and six groups of magnetic steel slots 1004 are provided on the inner side of the outer circle 1003 of the punching sheet. As shown Figure 1 and Figure 3As shown, six arrangement slots 8 are provided around the inner circle 1001 of the second punch 10. These slots 8 are located at the ends of the six ventilation holes 1002, and the arrangement slots 8 communicate with the ventilation holes 1002. Each ventilation hole 1002 of the second punch 10 has a slot 8 in the middle, which communicates with the ventilation hole 1002. Six arrangement slots 8 are provided around the outer circle 1003 of the second punch 10. Each arrangement slot 8 is located between two adjacent groups of magnetic steel slots 1004, and the arrangement slot 8 communicates with the side wall where the outer circle 1003 of the punch is located.

[0034] This embodiment further provides a method for testing the pressure between motor core laminations, which uses the above-mentioned structure for testing the pressure between motor core laminations and includes the following steps:

[0035] Step S1: Figure 5 As shown, the rotating shaft 1 is placed vertically, and the rotor pressing ring 2, multiple punching sheets, the pressure test structure between the motor core sheets, multiple punching sheets and the rotor pressing ring 2 are dropped in sequence, wherein the second punching sheet 10 is located on the top of the first punching sheet 9, and the first punching sheet 9 and the second punching sheet 10 are located in the middle of the motor core 3;

[0036] Step S2: Using a hydraulic press, apply a gradually increasing stacking force (0-200 kN, in increments of 10 kN) to the rotor pressing ring 3 on top of the motor core 3, record the pressure data of each pressure sensor 10 at each stacking force, sum the pressure data at each stacking force, plot a relationship between the stacking force and the sum of the pressure data, and fit the stacking force to the sum of the pressure data of each pressure sensor 7 using a fourth-order polynomial.

[0037] Step S3: Adjust the stacking pressure to 150KN. Figure 5 As shown, the motor core 3 is locked with the round nut 4 under the pressure, and then the stacking pressure of the hydraulic press is removed. The sum of the pressure data of each pressure sensor 7 at this time is recorded, and the corresponding stacking pressure is calculated using the fourth-order polynomial in step S2;

[0038] Step S4: Mark the data of each pressure sensor 7 in step S3 at the corresponding position of the second punching sheet 10 to obtain a pressure distribution diagram, and compare the pressure data of each pressure sensor 7 with the average pressure data of each pressure sensor 7 to determine the tightness of each area of ​​the second punching sheet 10;

[0039] Step S5: After the test is completed, open the round nut 4, remove the rotor pressure ring 2, multiple punching sheets, the first punching sheet 9 and the second punching sheet 10 in turn, remove each pressure sensor 7 and reuse it, and the first punching sheet 9 and the second punching sheet 10 can be remade according to different rotor core topologies.

[0040] The contents described in the above embodiments should be understood as these embodiments are only used to more clearly illustrate the invention, and are not used to limit the scope of the invention. After reading the present invention, various equivalent modifications to the embodiments made by those skilled in the art fall within the scope defined by the claims attached to the present invention.

Claims

1. A pressure monitoring structure between motor core sheets, characterized by: The invention comprises at least three pressure sensors (7), and uses two punching sheets in a motor core (3) as a first punching sheet (9) and a second punching sheet (10) for testing. The first punching sheet (9) and the second punching sheet (10) are fixedly connected along the thickness direction. The second punching sheet (10) is provided with a plurality of arrangement grooves (8). The pressure sensors (7) are respectively detachably fixed in the arrangement grooves (8), and the top of the pressure sensor (10) is flush with the outer surface of the second punching sheet (10).

2. The motor core pressure monitoring structure according to claim 1, characterized in that: The plurality of arrangement grooves (8) are evenly distributed on the second punching sheet (10), and a pressure sensor (7) is provided in each arrangement groove (8).

3. The motor core pressure monitoring structure according to claim 2, characterized in that: A plurality of arrangement grooves (8) are arranged in a ring shape on the second punching sheet (10).

4. The motor core pressure monitoring structure according to claim 2, characterized in that: The plurality of arrangement grooves (8) are respectively arranged around the punching plate inner circle (1001), the ventilation hole (1002) and the punching plate outer circle (1003) of the second punching plate (10), and the plurality of arrangement grooves (8) are arranged in a ring shape. The arrangement grooves (8) arranged around the punching plate inner circle (1201) are located in the inner ring area of ​​the second punching plate (10), the arrangement grooves (8) arranged around the ventilation hole (1002) are located in the middle ring area of ​​the second punching plate (10), and the arrangement grooves (8) arranged around the punching plate outer circle (1003) are located in the outer ring area of ​​the second punching plate (10).

5. The motor core pressure monitoring structure according to claim 4, characterized in that: The arrangement grooves (8) located around the inner circle (1001) of the punch are connected to the ventilation hole (1002) or are connected to the side wall where the inner circle (1001) of the punch is located; the arrangement grooves (8) located around the ventilation hole (1002) are connected to the ventilation hole (1002); and the arrangement grooves (8) located around the outer circle (1003) of the punch are connected to the side wall where the outer circle (1003) of the punch is located.

6. The motor core pressure monitoring structure according to claim 5, characterized in that: The motor core (3) is a rotor core, and a plurality of groups of magnetic steel slots (1004) are provided on the second punching sheet (10), and arrangement slots (8) located around the outer circle (1003) of the punching sheet are respectively arranged between two adjacent groups of magnetic steel slots (1004).

7. The motor core pressure monitoring structure according to claim 1, characterized in that: The arrangement groove (8) is a through hole along the thickness direction of the second punching sheet (10); the pressure sensor (7) adopts a thin film pressure sensor, the thickness of which is less than or equal to the thickness of the second punching sheet (10).

8. A method for testing pressure between motor core laminations, characterized by: The motor core lamination pressure testing structure according to any one of claims 1 to 7 comprises the following steps: Step S1: assembling the motor core (3) according to the assembly sequence, and placing the motor core inter-lamina pressure test structure between the laminations of the motor core (3); Step S2: applying different and gradually increasing stacking forces to the motor core (3), recording the pressure data of each pressure sensor (10) under each stacking force, summing the pressure data under each stacking force, and drawing a relationship diagram between the stacking force and the sum of the pressure data; Step S3: The stacking force is adjusted to the working pressure of the motor core (3), and the motor core (3) is fastened with a fastener under the pressure, and then the stacking force is removed, and the sum of the pressure data of each pressure sensor (7) at this time is recorded, and the stacking force corresponding to the sum of the pressure data is derived from the relationship diagram in step S2.

9. The method for testing the pressure between motor core laminations according to claim 8, wherein: In step S2, a polynomial is used to fit the stack pressure and the sum of the pressure data of each pressure sensor (7), or a relationship curve between the stack pressure and the sum of the pressure data of each pressure sensor (7) is drawn.

10. The method for testing pressure between motor core laminations according to claim 8, wherein: The method further comprises steps S4 and S5. Step S4: marking the data of each pressure sensor (7) in step S3 at the position corresponding to the second punching sheet (10) to obtain a pressure distribution diagram, and comparing the pressure data of each pressure sensor (7) with the average value of the pressure data of each pressure sensor (7), thereby judging the tightness of each area of ​​the second punching sheet (10); and step S5: after the test is completed, disassembling each pressure sensor (7) for reuse.

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