A design method for rotor multilayer casing

Abstract

The present invention provides a design method for a rotor multilayer sleeve, which relates to the field of motors, and comprises: obtaining data of a single-layer sleeve, constructing a multilayer sleeve model containing n sub-sleeves and having an average thickness based on the data of the single-layer sleeve, correcting the average thickness of each sub-sleeve based on the gradient change of shear stress in the radial direction of the single-layer sleeve and obtaining a corrected model, assembling the corrected model on a permanent magnet, and performing simulation to judge whether the radial and tangential stresses on the permanent magnet meet the strength requirements; the multilayer sleeve of the present application adopts a multilayer and small thickness form, which can reduce the span range of the overall stress of the multilayer sleeve without changing the mechanical properties of the motor rotor, and the stress distribution of each layer of the sub-sleeve is more uniform, thereby improving the utilization rate of the sleeve.

Description

Technical Field

[0001] The invention relates to the field of motors, and in particular to a design method for a rotor multi-layer sleeve. Background Art

[0002] Compared with traditional permanent magnet motors, high-speed permanent magnet motors have higher power density and greater performance advantages in many industrial fields, so they have become a hot spot in the development of motor science. However, the characteristics of high-speed motors make them more demanding in terms of strength and heat dissipation, and their development is also restricted for this reason. The speed of high-speed motors is relatively high, and the centrifugal force on their rotors is much greater than that of conventional permanent magnet motors. In order to enable the motor rotor to operate safely and stably under large centrifugal forces, corresponding measures need to be taken to protect the rotor; excessive temperature can also cause irreversible demagnetization of permanent magnets. Measures to solve the above problems usually use a single-layer carbon fiber sheath for protection.

[0003] The main structure of the rotor consists of three parts: the shaft, the permanent magnet and the surface-mounted sleeve. Figure 1 and 2 For a single-layer jacket, the equivalent stress it receives decreases linearly along the radius. The equivalent stress on the inner surface of the jacket is the largest, and the equivalent stress on the outer surface is the smallest. The force span on both sides is large, resulting in low efficiency of the single-layer jacket. In order to meet the design requirements, the design of the single-layer jacket needs to meet the extreme stress conditions in terms of jacket size and strength, so that the outer diameter part has redundant strength, resulting in a larger jacket size, heavier mass, and smaller stator-rotor gap. Summary of the invention

[0004] The present invention provides a design method for a rotor multi-layer sleeve, the purpose of which is to provide a design method for the multi-layer sleeve so as to make the overall force distribution of the multi-layer sleeve more uniform, improve the use efficiency of the sleeve, and reduce the total thickness of the multi-layer sleeve.

[0005] In order to achieve the above object, an embodiment of the present invention provides a design method for a rotor multilayer sleeve, which is characterized by comprising:

[0006] Obtaining data of a 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;

[0007] 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.

[0008] 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;

[0009] 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.

[0010] Preferably, in obtaining the single-layer sheath data, the shear stress value in the radial direction includes the maximum shear stress value σ max and the shear load w corresponding to the maximum shear stress s , max .

[0011] Preferably, in constructing the basic model, the number of sub-sheaths and the average thickness of the sub-sheaths are obtained by the equation group:

[0012]

[0013] Where n is the number of sub-sheaths, h is the sheath height, and w is 平 is the average thickness of the sub-sheath, and w is the total thickness of the single-layer sheath;

[0014] The maximum shear stress σ max and shear load w s , max Substituting into the equations, we can obtain the number of sub-sheaths n and the average thickness w of the sub-sheaths: 平 , the number n of sub-sheaths is rounded up.

[0015] Preferably, when correcting, w 平 As the thickness of the innermost sub-sheath, the thickness of each sub-sheath is thinned outwards layer by layer. The thickness of each sub-sheath after thinning is:

[0016]

[0017] In the formula, w ′ is the thickness of each layer of sub-sheath after thinning, w 平 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.

[0018] The above scheme of the present invention has the following beneficial effects:

[0019] In the present application, the multi-layer sheath adopts a multi-layer, small thickness form, which can reduce the overall stress span range of the multi-layer sheath without changing the mechanical properties of the motor rotor. The stress distribution of each layer of the sub-sheath is more uniform, which improves the utilization rate of the sheath and reduces the total thickness of the multi-layer sheath to a certain extent.

[0020] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of stress gradient of single-layer sheath;

[0022] Figure 2 is a schematic diagram of a single-layer sheath;

[0023] Figure 3 It is a schematic diagram of the process of the present invention. DETAILED DESCRIPTION

[0024] In order to make the technical problems, technical solutions and advantages to be solved by the present invention more clear, a detailed description will be given below with reference to the accompanying drawings and specific embodiments.

[0025] like Figure 3 As shown, an embodiment of the present invention provides a method for designing a rotor multilayer sleeve, comprising the following steps:

[0026] Obtain data of a single-layer sheath: A single-layer sheath is placed on the rotor, and the single-layer sheath is required to meet the radial and tangential stresses of the permanent magnets to meet the strength requirements. Measure the thickness of the single-layer sheath. Drive the rotor to move normally, and measure the radial value and gradient change of the shear stress σ of the single-layer sheath, where the shear stress σ includes the maximum shear stress σ max . Measure the value of shear load, which includes the maximum shear force w s , max .

[0027] Constructing a basic model of a multilayer sheath: Taking the thickness w of a single-layer sheath as a reference, construct a multilayer sheath including n sub-sheaths, wherein the n sub-sheaths are coaxially arranged from the inside to the outside, and the height of the sub-sheath is the same as that of the single-layer sheath.

[0028] Based on the shear stress calculation formula, the cross-sectional area formula and the cross-sectional area relationship between the sub-sheath and the multi-layer sheath, formula 1 is obtained. The shear stress calculation formula is:

[0029]

[0030] Where σ is shear stress, w s is the shear load, A 总 is the cross-sectional area of ​​a single-layer sheath.

[0031] The cross-sectional area formula is:

[0032] A=h×w 平

[0033] Where A is the cross-sectional area of ​​the sub-sheath, h is the height of the sub-sheath, and w is 平 is the average thickness of the sub-sheath. The cross-sectional area relationship between the sub-sheath and the multi-layer sheath is

[0034] A 总 =n×A

[0035] Where n is the number of sub-sheaths.

[0036] Formula 1 is:

[0037]

[0038] At the same time, the relationship between the thickness of the single-layer sheath and the average thickness of the sub-sheath is used as Formula 2, and Formula 1 and Formula 2 are used to construct an equation system, and the maximum shear stress σ max and the shear load w corresponding to the maximum shear stress s , max Substitute into the equations to obtain the number of sub-sheaths n and the average thickness of the sub-sheaths w 平 , with the number of sub-sheaths n and the average thickness of the sub-sheaths w 平 Build the base model.

[0039] Formula 2 is:

[0040] w=n×w 平

[0041] Where w is the thickness of the single-layer sheath, w 平 is the average thickness of the sub-sheath.

[0042] After obtaining the number n of sub-sheaths, if n is not an integer, n is rounded up.

[0043] The basic model of the multilayer sheath is modified to obtain the modified multilayer sheath model:

[0044] Specifically, w 平 As the thickness of the innermost sub-sheath, the thickness of each sub-sheath is thinned outward layer by layer to obtain the modified multi-layer sheath model. The thickness of each sub-sheath after thinning is:

[0045]

[0046] w ′ is the thickness of each layer of sub-sheath after thinning, w 平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.

[0047] Perform force analysis on the permanent magnet in the modified multi-layer sheath:

[0048] The modified multilayer sheath model is assembled on the permanent magnet, and the radial and tangential stresses of the permanent magnet in the modified multilayer sheath model are calculated. If the radial and tangential stresses of the permanent magnet meet the strength requirements, the modified multilayer sheath is qualified. If the radial and tangential stresses of the permanent magnet do not meet the strength requirements, the number of sub-sheaths is reduced by one in the basic model to obtain the average thickness w of the sub-sheaths after the number of sub-sheaths is reduced. 平 The basic model is reconstructed, the basic model is modified again, and the force analysis of the permanent magnet is performed until the radial and tangential stresses on the permanent magnet meet the strength requirements.

[0049] In the present application, the multi-layer sheath adopts a multi-layer, small thickness form, which can reduce the span range of the overall stress of the multi-layer sheath without changing the mechanical properties of the motor rotor, and the stress distribution of each layer of the sub-sheath is more uniform, which improves the utilization rate of the sheath and reduces the total thickness of the multi-layer sheath to a certain extent. When the total thickness is reduced, the cost of the multi-layer sheath is reduced, the wear of the multi-layer sheath is reduced, and the wind wear of the rotor is reduced.

[0050] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A design method for a rotor multilayer casing, characterized in that: include: Obtaining data of a 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 the rotor multilayer sleeve according to claim 1 is characterized in that: In obtaining single-layer jacket data, the shear stress values ​​in the radial direction include the maximum shear stress σ max and the shear load w corresponding to the maximum shear stress s，max .

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 from the equations: Where n is the number of sub-sheaths, h is the sheath height, and w is 平 is the average thickness of the sub-sheath, and w is the total thickness of the single-layer sheath; The maximum shear stress σ max and shear load w s，max Substituting into the equations, we can obtain the number of sub-sheaths n and the average thickness w of the sub-sheaths: 平 , 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: When correcting, w 平 As the thickness of the innermost sub-sheath, the thickness of each sub-sheath is thinned outwards layer by layer. The thickness of each sub-sheath after thinning is: Where w' is the thickness of each layer of sub-sheath after thinning, w 平 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.

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