CN118677143B

CN118677143B - Design method of rotor multilayer sheath

Info

Publication number: CN118677143B
Application number: CN202410688860.2A
Authority: CN
Inventors: 毛承清; 蒋煜东; 陈琪妍; 张恒; 阮金港; 张聪
Original assignee: Hunan Guoci Power Technology Co ltd
Current assignee: Hunan Guoci Power Technology Co ltd
Priority date: 2024-05-30
Filing date: 2024-05-30
Publication date: 2025-03-14
Anticipated expiration: 2044-05-30
Also published as: CN118677143A

Abstract

The application provides a design method of a rotor multilayer sheath, which relates to the field of motors and comprises the steps of obtaining data of a single-layer sheath, constructing a multilayer sheath model with n sub-sheaths and average thickness based on the data of the single-layer sheath, correcting the average thickness of each sub-sheath based on the gradient change of the tangential stress of the single-layer sheath in the radial direction, obtaining a corrected model, assembling the corrected model onto a permanent magnet, and carrying out simulation to judge whether the radial and tangential stress of the permanent magnet meets the strength requirement.

Description

Design method of rotor multilayer sheath

Technical Field

The invention relates to the field of motors, in particular to a design method of a rotor multilayer sheath.

Background

Compared with the traditional permanent magnet motor, the high-speed permanent magnet motor has higher power density and has larger performance advantages in a plurality of industrial fields, thereby becoming a hot spot for development of motor disciplines. But the characteristics of high-speed motors make their demands on strength and heat dissipation higher, and their development is limited for this reason. The rotating speed of the high-speed motor is larger, the centrifugal force born by the rotor is far larger than that of a conventional permanent magnet motor, corresponding measures are needed to protect the rotor in order to ensure that the motor rotor can safely and stably run under the larger centrifugal force, and the irreversible loss of the magnet can be caused by the too high temperature. Measures to solve the problems are usually protected by a single-layer carbon fiber sheath.

The main structure of the rotor consists of a rotating shaft, a permanent magnet and a surface-mounted sheath. Referring to fig. 1 and 2, for a single-layer sheath, the magnitude of the equivalent stress born by the sheath decreases linearly along the radial direction, the equivalent stress born by the inner surface of the sheath is the largest, the equivalent stress born by the outer surface is the smallest, and the stress spans on the inner side and the outer side are larger, so that the use efficiency of the single-layer sheath is lower. The single-layer sheath design is required to meet the limit stress conditions such as sheath size, strength and the like in order to meet the design requirement, so that the outer diameter part has redundant strength, and the designed sheath is larger in size, larger in mass and smaller in stator-rotor gap.

Disclosure of Invention

The invention provides a design method of a rotor multi-layer sheath, and aims to provide a design method of a multi-layer sheath, so that the overall stress distribution of the multi-layer sheath is more uniform, the service efficiency of the sheath is improved, and the total thickness of the multi-layer sheath is reduced.

In order to achieve the above object, an embodiment of the present invention provides a method for designing a rotor multi-layer jacket, which is characterized by comprising:

The method comprises the steps of obtaining data of a single-layer sheath, sleeving the single-layer sheath on a rotor, driving the rotor to normally operate, measuring the numerical value and gradient change of the shear stress of the single-layer sheath in the radial direction, and measuring the shear force load and the thickness of the single-layer sheath;

Constructing a basic model of the multi-layer sheath, namely constructing the basic model of the multi-layer sheath based on the thickness of the single-layer sheath, wherein the multi-layer sheath is formed by coaxially sleeving n sub-sheaths, the number of the sub-sheaths is obtained by combining the maximum shear stress and the shear force load with the height and the thickness of the single-layer sheath, and the average thickness of each sub-sheath in the multi-layer sheath is obtained based on the number of the sub-sheaths;

the basic model of the multilayer sheath is corrected to obtain a corrected multilayer sheath model, wherein the thickness of the inner-most layer sub sheath is maintained unchanged, and the thicknesses of other sub sheaths are reduced layer by layer based on the radial shear stress gradient change of the single-layer sheath, so as to obtain a corrected multilayer sheath;

And assembling the corrected multilayer sheath onto the permanent magnet for stress analysis, namely calculating radial and tangential stresses born by the permanent magnet, determining the number and thickness of the sub-sheaths if the radial and tangential stresses born by the permanent magnet meet the strength requirement, and reducing the number of the sub-sheaths by one if the radial and tangential stresses do not meet the strength requirement, and reconstructing a basic model and a corrected model.

Preferably, in acquiring the single-layer sheath data, the values of the shear stress in the radial direction include a shear stress maximum σ _max and a shear force load w _s,_max corresponding to the shear stress maximum.

Preferably, in constructing the base model, the number of sub-sheaths and the average thickness of the sub-sheaths are obtained from the set of equations:

Wherein n is the number of sub-sheaths, h is the sheath height, w _{Flat plate} is the average thickness of the sub-sheaths, and w is the total thickness of the single-layer sheath;

Substituting the maximum value sigma _max of the shear stress and the shear force load w _s,_max into the equation set to obtain the number n of the sub-jackets and the average thickness w _{Flat plate} of the sub-jackets, wherein the number n of the sub-jackets is rounded up.

Preferably, in the correction, w _{Flat plate} is taken as the thickness of the innermost sub-sheath, and the thickness of each layer of sub-sheath is thinned outwards layer by layer, and the thinned thickness of each layer of sub-sheath is as follows:

Wherein, w ^′ is the thickness of each layer of sub-sheath after thinning, w _{Flat plate} is the thickness of the innermost layer of sub-sheath, x is the stress magnitude corresponding to the stress gradient change corresponding to the sub-sheath, and F is the stress magnitude of the innermost layer of sub-sheath.

The scheme of the invention has the following beneficial effects:

In the application, the multilayer sheath adopts a mode of multiple layers and small thickness, the span range of the whole stress of the multilayer sheath can be reduced under the condition of not changing the mechanical property of the motor rotor, the stress distribution of each layer of sub-sheath is more uniform, the utilization rate of the sheath is improved, and the total thickness of the multilayer sheath is also reduced to a certain extent.

Additional features and advantages of the invention will be set forth in the detailed description which follows.

Drawings

FIG. 1 is a schematic illustration of the stress gradient of a single layer jacket;

FIG. 2 is a schematic illustration of a single layer sheath;

Fig. 3 is a schematic flow chart of the present invention.

Detailed Description

In order to make the technical problems, technical solutions and advantages to be solved more apparent, the following detailed description will be given with reference to the accompanying drawings and specific embodiments.

As shown in fig. 3, an embodiment of the present invention provides a method for designing a rotor multi-layer jacket, including the following steps:

And (3) acquiring data of the single-layer sheath, namely sleeving the single-layer sheath on the rotor, wherein the single-layer sheath is required to meet the requirement of strength of the permanent magnet on radial and tangential stress. The thickness of the single layer sheath was measured. The rotor is driven to normally move, and the numerical value and gradient change of the shear stress sigma of the single-layer sheath in the radial direction are measured, wherein the shear stress sigma comprises the maximum shear stress sigma _max. The magnitude of the shear force load, including the maximum shear force w _s,_max, was measured.

Constructing a basic model of the multi-layer sheath, namely constructing the multi-layer sheath comprising n sub-sheaths by taking the thickness w of the single-layer sheath as a reference, wherein the n sub-sheaths are coaxially sleeved outside from inside to outside, and the heights of the sub-sheaths are the same as those of the single-layer sheath.

And obtaining a formula I based on a shear stress calculation formula, a sectional area formula and a sectional area relation between the sub-sheath and the multi-layer sheath. The shear stress calculation formula is as follows:

where σ is the shear stress, w _s is the shear load, and a _{Total (S)} is the cross-sectional area of the single layer sheath.

The formula of the sectional area is:

A=h×w_{Flat plate}

wherein A is the sectional area of the sub-sheath, h is the height of the sub-sheath, and w _{Flat plate} is the average thickness of the sub-sheath. Sub-sheath and multi-layer sheath the cross-sectional area relationship is that

A_{Total (S)}=n×A

Where n is the number of sub-jackets.

The first formula is:

Meanwhile, taking the relation between the thickness of the single-layer sheath and the average thickness of the sub-sheaths as a formula II, constructing an equation set by using the formula I and the formula, substituting the shear stress maximum value sigma _max and the shear force load w _s,_max corresponding to the shear stress maximum value into the equation set to obtain the number n of the sub-sheaths and the average thickness w _{Flat plate} of the sub-sheaths, and constructing a basic model by using the number n of the sub-sheaths and the average thickness w _{Flat plate} of the sub-sheaths.

The formula II is:

w=n×w_{Flat plate}

Where w is the thickness of the single layer sheath and w _{Flat plate} is the average thickness of the sub-sheath.

After the number n of sub-jackets is obtained, if n is not an integer, n is rounded up.

Correcting the basic model of the multilayer sheath to obtain a corrected multilayer sheath model:

specifically, w _{Flat plate} is taken as the thickness of the innermost sub-sheath, the thickness of each layer of sub-sheath is thinned outwards layer by layer to obtain a corrected multi-layer sheath model, and the thinned thickness of each layer of sub-sheath is as follows:

w ^′ is the thickness of each layer of sub-sheath after thinning, w _{Flat plate} is the thickness of the innermost layer of sub-sheath, x is the stress corresponding to the stress gradient change of the sub-sheath, and F is the stress of the innermost layer of sub-sheath.

And carrying out stress analysis on the permanent magnet in the corrected multilayer sheath:

Assembling the corrected multilayer sheath model on the permanent magnet, calculating the radial and tangential stresses of the permanent magnet in the corrected multilayer sheath model, if the radial and tangential stresses of the permanent magnet meet the strength requirement, the corrected multilayer sheath is qualified, if the radial and tangential stresses of the permanent magnet do not meet the strength requirement, the number of the sub-sheaths in the basic model is reduced by one, the average thickness w _{Flat plate} of the sub-sheaths after the number of the sub-sheaths is reduced is obtained, the basic model is reconstructed, and the basic model is corrected again, and the stress analysis is carried out on the permanent magnet until the radial and tangential stresses of the permanent magnet meet the strength requirement.

In the application, the multilayer sheath adopts a mode of multiple layers and small thickness, the span range of the whole stress of the multilayer sheath can be reduced under the condition of not changing the mechanical property of the motor rotor, the stress distribution of each layer of sub-sheath is more uniform, the utilization rate of the sheath is improved, and the total thickness of the multilayer sheath is also reduced to a certain extent. When the total thickness is reduced, the cost of the multilayer jacket is reduced, the wear of the multilayer jacket is reduced, and the wind wear of the rotor is reduced.

While the foregoing is directed to the preferred embodiments of the present invention, it will be appreciated by those skilled in the art that various modifications and adaptations can be made without departing from the principles of the present invention, and such modifications and adaptations are intended to be comprehended within the scope of the present invention.

Claims

1. A method for designing a rotor multilayer sheath, comprising:

Obtaining data of the single-layer sheath: a single-layer sheath is placed on the rotor, and the rotor is driven to operate normally, and the value and gradient change of the shear stress of the single-layer sheath in the radial direction are measured, and the shear force load and the thickness of the single-layer sheath are measured;

Constructing a basic model of a multilayer sheath: Based on the thickness of a single-layer sheath, construct a basic model of a multilayer sheath, in which the multilayer sheath is composed of n sub-sheaths coaxially arranged. The number of sub-sheaths is obtained by combining the maximum shear stress and shear force load with the height and thickness of the single-layer sheath. Based on the number of sub-sheaths, the average thickness of each sub-sheath in the multilayer sheath is obtained.

The basic model of the multilayer jacket is modified to obtain a modified multilayer jacket model: the thickness of the innermost sub-jacket is kept unchanged, and the thickness of other sub-jackets is gradually reduced based on the shear stress gradient change of the single-layer jacket in the radial direction to obtain a modified multilayer jacket;

The revised multi-layer sheath is assembled on the permanent magnet for force analysis: the radial and tangential stresses on the permanent magnet are calculated. If the radial and tangential stresses on the permanent magnet meet the strength requirements, the number and thickness of the sub-sheaths are determined; if not, the number of sub-sheaths is reduced by one, and the basic model and the revised model are reconstructed.

2. The design method of a rotor multilayer sleeve according to claim 1 is characterized in that: in obtaining the single-layer sleeve data, the value of the shear stress in the radial direction includes the maximum shear stress value σ _max and the shear force load w _s,max corresponding to the maximum shear stress value.

3. The design method of the rotor multilayer sleeve according to claim 2 is characterized in that:

In constructing the basic model, the number of sub-sheaths and the average thickness of the sub-sheaths are obtained by the equation group:

Where n is the number of sub-sheaths, h is the height of the sheath, w _is the average thickness of the sub-sheath, and w is the total thickness of the single-layer sheath;

Substituting the maximum shear stress σ _max and the shear force load w _s,max into the equation group, the number n of sub-sheaths and the average thickness w _flat of the sub-sheaths are obtained, and the number n of sub-sheaths is rounded up.

4. The design method of the rotor multilayer sleeve according to claim 3 is characterized in that:

During the correction, w _level is used as the thickness of the innermost sub-sheath, and the thickness of each sub-sheath is thinned layer by layer outwards. The thickness of each sub-sheath after thinning is:

Wherein, w' is the thickness of each layer of sub-sheath after thinning, w _level is the thickness of the innermost sub-sheath, x is the force magnitude corresponding to the force gradient change of the sub-sheath, and F is the force magnitude of the innermost sub-sheath.