Method and system for coordinated weight reduction of motor-housing of a ducted fan

Abstract

The application relates to the technical field of precision machining measurement, in particular to a motor-shell collaborative weight-reducing assembly method and system of a ducted fan, which comprises the following steps: obtaining assembly design parameters of a motor and a shell under the condition that total assembly weight-reducing constraints are met, and calculating vibration intensity based on the assembly design parameters; wherein the assembly design parameters comprise motor rotor mass, motor rotor angular velocity, eccentricity of a motor rotor mass center relative to a rotating axis, eccentric mass coefficient, vibration transmission path efficiency, shell effective bearing area and shell material allowable stress; and determining whether the assembly quality of the motor and the shell is qualified based on the vibration intensity and obtained assembly process parameters. The application can accurately realize collaborative weight-reducing assembly of the motor and the shell under the premise of meeting total assembly weight-reducing constraints, and improve assembly quality and assembly precision.

Description

Technical Field

[0001] This application relates to the field of precision machining and measurement technology, specifically to an assembly method and system for coordinated weight reduction of the motor and housing of a ducted fan. Background Technology

[0002] Ductless fans are widely used in aero engines, drone propulsion systems, and industrial ventilation equipment. In the design of ducted fans, the assembly quality of the motor and housing directly affects the overall performance, reliability, and service life of the unit.

[0003] Currently, when designing a coordinated weight reduction assembly for the motor and housing, the common approach is to optimize the motor structure and housing structure separately.

[0004] However, the main problem with this assembly method is that the overall assembly quality (such as assembly weight and assembly accuracy) of the separately designed motor and housing may not meet the expected requirements after assembly, affecting the performance and reliability of the whole machine. Summary of the Invention

[0005] This application provides an assembly method and system for coordinated weight reduction of the motor and housing of a ducted fan, which can accurately achieve coordinated weight reduction assembly of the motor and housing while meeting the overall assembly weight reduction constraints, thereby improving assembly quality and assembly accuracy.

[0006] In a first aspect, this application provides an assembly method for coordinated weight reduction of the motor and housing of a ducted fan, the method comprising: Under the condition that the weight reduction constraint of the overall assembly is met, the assembly design parameters of the motor and the housing are obtained, and the vibration intensity is calculated based on the assembly design parameters. Among them, the assembly design parameters include the motor rotor mass, the motor rotor angular velocity, the eccentricity of the motor rotor center of mass relative to the axis of rotation, the eccentricity mass coefficient, the vibration transmission path efficiency, the effective bearing area of ​​the housing, and the allowable stress of the housing material. Based on the vibration intensity and the acquired assembly process parameters, it is determined whether the assembly quality of the motor and the housing is up to standard.

[0007] Secondly, this application provides an assembly system for coordinated weight reduction of the motor and housing of a ducted fan, the system comprising: The vibration intensity calculation module is used to obtain the assembly design parameters of the motor and the housing under the condition that the overall assembly weight reduction constraint is met, and to calculate the vibration intensity based on the assembly design parameters. Among them, the assembly design parameters include the motor rotor mass, the motor rotor angular velocity, the eccentricity of the motor rotor center of mass relative to the rotation axis, the eccentricity mass coefficient, the vibration transmission path efficiency, the effective bearing area of ​​the housing, and the allowable stress of the housing material. The assembly process inspection module is used to determine whether the assembly quality of the motor and housing is up to standard based on vibration intensity and acquired assembly process parameters.

[0008] As can be seen from the above technical solution, this application has at least the following beneficial effects: 1) This application obtains the assembly design parameters of the motor and housing while ensuring that the overall assembly weight reduction constraint is met, and comprehensively considers the weight reduction target and assembly quality, thus achieving a coordinated weight reduction design for the motor and housing. This approach changes the problem of uncontrollable overall assembly quality caused by optimizing the motor and housing separately in the traditional method, ensuring that the assembly quality is effectively guaranteed while achieving the weight reduction target; 2) This application determines whether the assembly quality of the motor and housing is qualified based on vibration intensity and acquired assembly process parameters. Vibration intensity, as a characteristic parameter, allows for the quantitative assessment of the impact of factors such as motor rotor eccentricity and housing dynamic response on assembly quality. The assembly quality qualification determination ensures that each assembly meets performance requirements, preventing defective products from flowing into subsequent processes, thereby improving the overall performance and reliability of the machine. 3) This application introduces vibration intensity as a characteristic parameter to quantitatively evaluate assembly quality. Vibration intensity is related to parameters such as motor rotor mass, angular velocity, effective bearing area of ​​the housing, and allowable material stress, enabling the calculation and determination of assembly quality. This quantitative evaluation method provides an objective basis for assembly quality control and solves the problem that assembly accuracy and weight may not meet expectations in traditional methods. Attached Figure Description

[0009] Figure 1 A flowchart illustrating an assembly method for coordinated weight reduction of a ducted fan motor and housing, provided in an embodiment of this application; Figure 2 This is a schematic diagram of an assembly method system for coordinated weight reduction of a ducted fan motor and housing, provided in an embodiment of this application. Detailed Implementation

[0010] To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings. The described embodiments should not be regarded as limitations on this application. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0011] The manufacturing of ducted fan housings involves a complete technology chain with multiple coupled processes and progressively increasing precision, encompassing several consecutive stages including casting, process inspection, heat treatment control, dimensional finishing, and final performance verification. Within this technology chain, the systematic integration and performance verification of the final assembly stage play a crucial role: if the final stage cannot transform the accumulated geometric precision and material properties of the upstream processes into overall machine performance that meets design specifications, the entire manufacturing process will struggle to form an effective product value loop, and all the precision control achievements from the early stages will not be fully realized in the final product. Therefore, achieving a paradigm shift from "single-process qualification" to "overall machine performance compliance" is a core prerequisite for ensuring that the entire manufacturing process ultimately converges to the design goals.

[0012] In the aforementioned technology chain, the motor-housing assembly process is the final node of the entire process. It plays a crucial role in integrating the independently manufactured motor and housing into a fully functional propulsion unit. It also serves as the final comprehensive verification stage for the manufacturing precision and form consistency of each upstream stage. After casting, heat treatment control, and dimensional finishing, the housing's wall thickness distribution, geometric contour, and internal structural benchmarks are solidified; the motor rotor's mass, speed, and other parameters are also determined. The assembly stage, while meeting overall weight reduction constraints, verifies the dynamic performance and structural safety of the matched motor and housing through systematic parameter coupling calculations. The synergistic weight reduction and performance compliance achieved in this stage constitute the core performance benchmark for the final delivery of the technology chain.

[0013] However, existing assembly methods suffer from a bottleneck that hinders the realization of full-process value: they typically employ a step-by-step, independent assembly and post-assembly sampling inspection model, failing to establish an assembly quality prediction model based on the dynamic coupling of the motor-casing system. For precision propulsion systems like ducted fans, which have stringent requirements for vibration characteristics and structural lightweighting, empirical assembly and static sampling inspection cannot match the complex coupling relationship between rotor dynamics and casing load-bearing characteristics, leading to deviations between the actual vibration intensity after assembly and the theoretical design value. This integration misalignment will trigger serious cascading consequences: excessive vibration of the assembled propulsion unit will directly threaten the stability and safety of the flight platform; insufficient local load-bearing margin of the casing will limit the implementation boundaries of lightweighting and weight reduction; ultimately, the aerodynamic efficiency, structural lifespan, and mission reliability of the entire aircraft cannot be fully guaranteed.

[0014] Based on this, such as Figure 1 As shown, this embodiment provides a method for synergistic weight reduction assembly of a motor and a housing, specifically including the following steps S101 to S102: Step S101: Under the condition that the weight reduction constraint of the overall assembly is met, obtain the assembly design parameters of the motor and the housing, and calculate the vibration intensity based on the assembly design parameters.

[0015] This application addresses the problem of uncontrollable overall assembly quality caused by separately optimizing the motor structure and housing structure in existing technologies, and provides a collaborative weight reduction assembly method for the motor and housing. The core inventive point of this application lies in: introducing vibration intensity as a characteristic parameter, and linking the overall assembly weight reduction constraint with the assembly quality qualification judgment, thereby achieving a collaborative weight reduction design for the motor and housing.

[0016] Before designing the assembly of the motor and housing, it is necessary to first determine the overall assembly weight reduction constraints. The core invention of this application is to achieve coordinated weight reduction design of the motor and housing, and the prerequisite for coordinated weight reduction is to clearly define the weight reduction target. Only when the overall assembly weight reduction constraints are met can subsequent vibration intensity calculations and assembly quality assessments have practical significance.

[0017] The sources of weight reduction constraints in final assembly include three typical scenarios: First, the design requirements based on the application scenario are determined, such as the need to strictly control the weight of the power system for ducted fans in drones; second, the optimization objectives based on performance goals are determined, such as the requirement for industrial high-speed fans to reduce the casing mass by a certain percentage compared to traditional solutions; and third, the material usage is determined based on cost control, such as the need to limit casing volume or material costs for consumer electronics products.

[0018] After confirming that the overall assembly weight reduction constraint is met, the assembly design parameters for the motor and housing are obtained. These parameters include the motor rotor mass, motor rotor angular velocity, effective bearing area of ​​the housing, and allowable stress of the housing material.

[0019] The first parameter: motor rotor mass This refers to the mass of the motor rotor, measured in kilograms (kg). The rotor mass is a necessary parameter for calculating the vibration excitation source (centrifugal force). According to physics, the essence of the vibration excitation source is the centrifugal force generated by the rotation of an eccentric mass. The centrifugal force is directly proportional to the rotor mass; the greater the rotor mass, the greater the centrifugal force generated, and the stronger the vibration excitation source. Methods for obtaining this mass include: directly extracting the rotor mass parameter from the motor specifications or design BOM; calculating the rotor mass using the attribute query function of CAD software (suitable for the design stage); or weighing the rotor using a precision electronic balance (suitable for situations where a physical sample is available).

[0020] The second parameter: motor rotor angular velocity. This refers to the angular velocity of the motor rotor during operation, measured in radians per second (rad / s). The rotor angular velocity is another essential parameter for calculating centrifugal force. In the calculation of vibration excitation sources, centrifugal force is proportional to the square of the angular velocity. This means that methods of obtaining this velocity include: reading the real-time rotational speed from the motor controller. (Unit: RPM), which can be converted to angular velocity using a formula; or the rated speed can be obtained from the motor specification sheet as a design input parameter.

[0021] The third parameter: eccentricity. Eccentricity It refers to the radial offset of the rotor's center of mass relative to the axis of rotation, and the unit is meters (m).

[0022] Eccentricity is the direct cause of vibration excitation. The essence of vibration excitation is the centrifugal force generated by the rotation of the eccentric mass. If the rotor's center of mass is exactly on the axis of rotation (eccentricity is zero), then no matter how large the rotor mass or how high the rotational speed, no centrifugal force will be generated, and there will be no vibration excitation problem. It is precisely because of the existence of eccentricity that centrifugal force is generated.

[0023] The sources of eccentricity include four aspects: First, machining errors such as uneven stacking of the rotor core and dimensional deviations in the rotor shaft machining; second, assembly errors such as positioning deviations during rotor-housing assembly; third, operational deformations such as centrifugal deformation during high-speed rotation and thermal expansion deformation caused by temperature changes; and fourth, material inhomogeneity factors such as uneven distribution of rotor material density. Methods for obtaining eccentricity include: measuring the rotor's imbalance using a dynamic balancing machine and converting it into an equivalent eccentricity; or estimating the equivalent eccentricity by measuring the coaxiality deviation between the rotor shaft and the housing bearing holes, combined with the rotor's mass distribution.

[0024] The fourth parameter: eccentricity mass coefficient Eccentricity mass coefficient It is a dimensionless parameter characterizing the ratio of eccentric mass to the total rotor mass, and its physical meaning is:

[0025] in The effective eccentric mass for generating vibration excitation.

[0026] The actual vibration excitation is not generated by the entire mass of the rotor, but rather by the uneven distribution of the rotor's mass relative to the axis of rotation. Eccentric mass coefficient. Usually in The magnitude of the eccentricity mass coefficient depends on the rotor's machining accuracy and dynamic balance level. It can be obtained by: inferring the eccentricity mass coefficient through dynamic balancing tests; or by using empirical values ​​based on the rotor's structural characteristics and machining technology level.

[0027] The fifth parameter: Effective bearing area of ​​the shell. This refers to the windward area of ​​the shell receiving vibration excitation in the vibration transmission path, measured in square meters (m²). The complete path of vibration transmission from the rotor to the shell is: rotor (eccentric mass generates centrifugal force) → bearing (supports and transmits force) → end cover (serves as an intermediate force transmission component) → shell (receives vibration excitation and generates forced vibration).

[0028] The effective bearing area specifically refers to the projected area of ​​the contact region between the end cap and the shell in the vibration transmission direction. It can be obtained by: measuring the projected area of ​​the flange surface in contact with the shell using CAD software and multiplying it by a transmission efficiency coefficient (considering the non-uniform transmission characteristics of bolted connections); calculating the effective bearing area by measuring key geometric dimensions of the shell; or inferring the effective bearing area through vibration testing experiments.

[0029] The sixth parameter: Allowable stress of the shell material. This refers to the allowable stress value of the shell material under vibration load, measured in Pascals (Pa). Methods of obtaining this value include: referring to the yield strength or tensile strength from the material handbook based on the material used in the shell, and then applying the formula... Calculate the allowable stress (where (For safety factors); or by directly measuring the yield strength through a material tensile test; or by obtaining material performance parameters from the supplier's specifications.

[0030] Based on the six assembly design parameters obtained above, the vibration load and vibration intensity are calculated.

[0031] Step 1: Calculate the vibration excitation force The essence of vibration excitation force is the centrifugal force generated by the rotation of the eccentric mass. Considering the eccentric mass coefficient, the eccentric mass... Represented as:

[0032] When the rotor is at angular velocity During rotation, due to eccentricity The centrifugal force generated is:

[0033] In the above formula, the rotor mass Through the eccentricity mass coefficient Converted to effective eccentric mass This ensures that the calculation of vibration excitation force has a physical basis. The introduction of this technology solved the problem that the total mass of the rotor was much greater than the actual eccentric mass.

[0034] Step 2: Consider transmission path attenuation The vibration excitation force is transmitted from the rotor to the housing through bearings, end covers, and other force transmission components, resulting in transmission attenuation. The vibration load after attenuation along the transmission path is:

[0035] in Transmission path efficiency, in its physical sense, is the effective proportion of vibrational energy transferred from the excitation source to the shell. It depends on the stiffness and damping characteristics of each link in the transmission path. Typical transmission paths include: rotor → bearing: affected by bearing type (rolling bearing, sliding bearing), bearing preload, and lubrication condition; bearing → end cover: affected by connection stiffness and bolt preload; end cover → housing: affected by flange surface contact stiffness and seal stiffness.

[0036] In engineering applications, The transfer efficiency can be obtained through the following methods: Theoretical calculation: establishing the transfer function based on the stiffness-damping model of each transmission link; Finite element analysis: establishing a dynamic model including each connection interface; Experimental testing: determining the transmission efficiency by measuring the frequency response function (FRF) through excitation experiments; Empirical values: for typical motor-housing assemblies, the value range is usually [range missing]. .

[0037] Step 3: Calculate vibration intensity Vibration intensity This is the core inventive point of this application, and its physical definition is the ratio of vibration load to the effective bearing area of ​​the shell and the allowable stress of the material:

[0038] This represents the normalized ratio of vibration stress to the material's allowable stress. when At that time, the vibration stress was within the allowable range of the material; when At that time, the vibration stress is equal to the material's allowable range; when At that time, the vibration stress exceeded the allowable range of the material.

[0039] Step S102: Based on the vibration intensity and the obtained assembly process parameters, determine whether the assembly quality of the motor and the housing is qualified.

[0040] Based on the vibration intensity and the acquired assembly process parameters, the assembly quality of the motor and housing is determined to be acceptable. The vibration intensity is calculated in step S101. Then, based on vibration intensity By considering assembly process parameters, it is possible to determine whether the assembly quality of the motor and housing is up to standard. Assembly quality is not only related to vibration load, but also closely related to torque transmission capability, heat transmission capability, and electromagnetic shielding capability. Considering vibration intensity alone cannot comprehensively evaluate assembly quality. For example, if the heat dissipation area is insufficient after the housing is reduced in weight, it may lead to low efficiency of the heat transfer interface; if the electromagnetic connection point is not designed properly, it may lead to electromagnetic shielding failure. Therefore, it is necessary to comprehensively consider the assembly process parameters in four dimensions: mechanical transmission, torque transmission, heat transmission, and electromagnetic transmission.

[0041] S102-1: Calculation of the efficiency of the mechanical transmission interface Assembly process parameters include: torque transmission interface assembly parameters, heat transmission interface assembly parameters, electromagnetic transmission interface assembly parameters, and the eccentricity between the motor rotor and the housing. (The eccentricity has been obtained in step S101).

[0042] Mechanical transmission interface efficiency It is a dimensionless parameter used to assess the integrity of vibration energy transmission at the mechanical transmission interface.

[0043] The mechanical transmission interface efficiency reflects the effectiveness of transmitting vibration excitation from the rotor through bearings and end caps to the housing. This efficiency comprehensively considers the influence of the excitation source intensity caused by eccentricity and the interface fretting caused by vibration intensity on the transmission path. A higher efficiency value indicates that the energy of the vibration excitation transmitted to the housing is closer to the theoretical value, i.e., the better the mechanical integrity of the transmission path; a lower efficiency value indicates that there is looseness or gaps in the transmission path, and the vibration energy attenuates during transmission. By introducing a vibration correction coefficient, the influence of vibration intensity on transmission efficiency can be quantified into a calculable parameter.

[0044] Eccentricity and vibration intensity As input parameters, the efficiency of the mechanical transmission interface is calculated based on the pre-established mapping relationship between mechanical transmission efficiency, eccentricity, and vibration intensity.

[0045] For example, the physical relationship between eccentricity and vibration intensity is: eccentricity Generates unbalanced centrifugal force (in For rotor mass, (where angular velocity is the rotational velocity), this centrifugal force excites the shell structure to produce a vibration response, which is then converted into vibration intensity. (in For the shell dynamic stiffness, (Rated displacement). The mapping relationship between the efficiency of the mechanical transmission interface and the eccentricity and vibration intensity is as follows:

[0046] in As a benchmark efficiency, This is the eccentricity influence coefficient (unit: 1 / m). The vibration intensity influence coefficient (dimensionless); the first term The second term reflects the impact of uneven contact pressure distribution caused by eccentricity on efficiency. The vibration intensity reflects the effect of interface fretting caused by vibration on efficiency. It is itself an eccentric distance The function is used to achieve the coupling effect between the two.

[0047] This mapping reflects the coupled influence of eccentricity and vibration intensity on the efficiency of the mechanical transmission interface. A larger eccentricity results in stronger vibration excitation; a greater vibration intensity leads to a more significant vibration response. Both factors jointly determine the efficiency of the mechanical transmission interface.

[0048] S102-2: Calculation of Torque Transmission Interface Efficiency Torque transmission interface efficiency It is a dimensionless parameter that evaluates the degree to which torque is effectively transmitted at the torque transmission interface.

[0049] The motor needs to transmit torque to the housing to drive the ducted fan. Torque transmission interfaces include various forms such as tapered connections, hub connections, and keyed connections. Vibration can affect the friction state and preload of the connection interface, thus impacting torque transmission capability.

[0050] The torque transmission interface assembly parameters include: Taper angle of tapered connection structure (Unit: degrees, °); Interference of the hub connection structure (Unit: meters, m); Number of keys in a key-connected structure (dimensionless); Basic coefficient of friction of the connection interface (dimensionless); Rated torque (Unit is Newton-meter, N·m).

[0051] Step 1: Based on vibration intensity and basic friction coefficient Calculate the vibration-corrected friction coefficient

[0052] The formula for calculating the vibration-corrected friction coefficient is:

[0053] in: This is the vibration friction correction factor (dimensionless), and its value range is typically [value range missing]. This can be determined through vibration and friction tests; The physical lower limit (dimensionless) of the coefficient of friction is determined based on the material pairing (for steel-to-steel contact, it is usually taken as...). =0.05 0.1).

[0054] The effect of vibration on the coefficient of friction is mainly manifested in the following ways: vibration causes micro-slippage on the contact surface, disrupting the static friction state and reducing the effective coefficient of friction. Therefore, the following methods are adopted: The form is modified, and a lower bound constraint is introduced. To prevent the calculation results from falling below the physical limits:

[0055] in: This is the vibration friction correction factor (dimensionless), and its value range is typically [value range missing]. ; The physical lower limit (dimensionless) of the coefficient of friction is determined based on the material pairing (for steel-to-steel contact, it is usually taken as...). ).

[0056] Step 2: Correct the friction coefficient based on vibration. With taper angle Interference Number of keys and rated torque Parameters for calculating torque transmission interface efficiency

[0057] The formula for calculating the torque transmission interface efficiency is:

[0058] in The actual transmittable torque (in N·m). Rated torque (in N·m).

[0059] Actual transmittable torque It consists of the following three components:

[0060] (1) Tapered connection transmits torque

[0061] Tapered connections transmit torque through friction on the tapered surface; the calculation formula is as follows:

[0062] in: The axial preload force (in N) for the tapered connection is described later. The average radius of the tapered surface (in meters); It is the taper half angle (in degrees), that is, the angle between the cone surface and the axis of rotation; This is the component of the axial preload in the normal direction of the conical surface, i.e., the normal clamping force of the conical surface.

[0063] Axial preload How to obtain: Axial preload is the source of radial clamping force in tapered connections, and it can be obtained through methods including: Calculation method: For tapered structures using bolted connections, Determined by the bolt preload. ,in For bolt preload transmission efficiency (usually ); Measurement method: Use a torque wrench to measure the tightening torque, and then use the formula... Calculate the preload, where The torque coefficient, The nominal diameter of the bolt; Experimental method: Axial force was directly measured using strain gauges or pressure sensors during the assembly process.

[0064] (2) Torque transmission via hub connection

[0065] The shaft-hub connection transmits torque through the radial clamping force generated by the interference fit. The calculation formula is as follows:

[0066] in: The radial clamping force (in N) for the hub-and-shaft connection is calculated using the following formula: ,in To match the pressure (and interference) (proportional) To match the diameter, To match the length; The average radius of the hub surface (in meters).

[0067] (3) Key connection transmits torque

[0068] Keyed connections primarily transmit torque through the shear strength and compressive strength of the key, and their calculation formula is as follows:

[0069] in: The number of bonds (dimensionless); The shear capacity of a single key (in N·m) is calculated using the following formula:

[0070] in Shear area of ​​the bond ( For bond width, (for bond length) The allowable shear stress of the bonding material. The shaft diameter; The compressive bearing capacity of a single bond (in N·m) is calculated using the following formula:

[0071] in The compression area of ​​the bond ( (for key height) This represents the allowable compressive stress of the keyway.

[0072] Keyed connections primarily rely on the shear strength of the key and the compressive strength of the bearing surface to transmit torque, rather than friction. This is because there is usually a gap between the key and the keyway in a keyed connection, and the mating surfaces cannot generate sufficient normal pressure to transmit torque through friction. Therefore, this application modifies the torque calculation for keyed connections by using a shear / compression mechanism, which better reflects the actual force transmission mechanism of keyed connections.

[0073] Based on the vibration-corrected friction coefficient calculated in step S102-2, the influence of temperature on the tapered connection structure is further considered, resulting in step S102-2-1. When the motor operates for an extended period, a temperature gradient exists between the housing and the motor shaft, leading to axial thermal deformation differences and consequently causing relaxation of the hot preload of the tapered connection. Therefore, this step adds thermal deformation analysis to S102-2 to perform thermal correction on the torque component transmitted by the tapered connection. Step S102-2-1 includes the following steps: The first step is that during motor operation, the tapered connection structure is in a thermally coupled environment. One end of the tapered connection mates with the housing, and the other end mates with the motor shaft. Therefore, it is necessary to obtain the temperature parameters of the housing and the motor shaft separately.

[0074] Temperature parameters for the housing include: operating temperature of the tapered fit area of ​​the housing. (Unit: °C or Kelvin K); Shell reference temperature (Usually taken as the ambient temperature during assembly); Temperature parameters of the motor shaft include: operating temperature of the tapered fit area of ​​the motor shaft. (Unit: °C or Kelvin K); Motor shaft reference temperature (Usually taken as the ambient temperature during assembly;)

[0075] The methods for obtaining temperature parameters include: thermocouple measurement: pre-setting temperature measurement points in the tapered fit area and directly measuring the operating temperature using K-type or N-type thermocouples; infrared temperature measurement: using an infrared thermal imager to non-contactly measure the surface temperature distribution in the tapered fit area; thermal simulation calculation: obtaining theoretical temperature values ​​through finite element thermal analysis based on motor losses and heat dissipation conditions; and empirical estimation: estimating the temperature rise using empirical formulas based on the motor's rated power and heat dissipation conditions.

[0076] Step 2: Calculation of Axial Thermal Deformation Difference: The materials of the housing and the motor shaft are different, and therefore have different coefficients of thermal expansion. When both are subjected to the same temperature change, there is a difference in thermal expansion; when their temperatures are different, the difference in thermal expansion is more significant. The axial thermal deformation difference of the tapered connection structure is:

[0077] in: is the coefficient of thermal expansion of the shell material (in units of 1 / K); The coefficient of thermal expansion of the motor shaft material (in units of 1 / K); The characteristic length of the taper fit (in meters) is usually taken as the axial length of the taper fit section; This represents the temperature rise of the casing relative to the reference temperature. This represents the temperature rise of the motor shaft relative to the reference temperature.

[0078] like This indicates that the thermal expansion on the housing side is greater than that on the motor shaft side, resulting in axial loosening of the tapered connection; if This indicates that the thermal expansion on the motor shaft side is greater than that on the housing side, which may cause the tapered connection to be too tight.

[0079] Step 3: Calculation of Hot Preload Relaxation: The preload of the tapered connection structure originates from the axial clamping during assembly. Axial thermal deformation difference This causes a change in the contact state between the tapered mating surfaces, resulting in a relaxation of the preload.

[0080] The formula for calculating the relaxation amount of hot preload is:

[0081] in The axial equivalent stiffness of the tapered connection structure (in N / m) depends on the contact stiffness and taper angle of the tapered mating surface.

[0082] Axial equivalent stiffness The stiffness can be obtained through the following methods: analytical calculation: derived based on Hertz contact theory and taper geometry; finite element analysis: establishing a contact analysis model of taper fit and applying thermal load to obtain stiffness; experimental testing: measuring the axial force-displacement relationship through axial loading tests to calibrate the axial stiffness.

[0083] Step 4: Calculation of the initial radial clamping force for the hot-corrected radial clamping force of the tapered connection structure. Due to the axial preload during assembly and taper half angle Decision. Axial preload. The component of the cone surface normal is:

[0084] The radial component of the normal force (perpendicular to the axis) is:

[0085] After considering the relaxation of the hot preload, the hot-corrected radial clamping force is:

[0086] in: For hot-condition correction of radial clamping force (in N); This is the initial radial clamping force (cold state, in N). This is the relaxation amount of the hot axial preload (in N). When the axial preload is relaxed At that time, the reduction in radial clamping force is: .

[0087] Step 5: Calculation of the efficiency of the torque transmission interface under thermal correction: After comprehensively considering vibration correction and thermal correction, the thermal correction value for the torque transmission of the tapered connection is: The positive torque that a tapered connection can transmit under hot conditions is:

[0088] in:

[0089] This refers to the axial preload during hot operation. in Torque (in N·m) is transmitted to the tapered connection after thermal correction.

[0090] Actual transmittable torque The hot-state correction expression is:

[0091] in and The calculation method is consistent with that in step S102-2.

[0092] The formula for calculating the thermally corrected torque transmission interface efficiency is:

[0093] When the motor is in thermal equilibrium, the relaxation of the thermal preload of the tapered connection structure may lead to a decrease in torque transmission capability. In this case, the efficiency after thermal correction should be used. As a basis for evaluation, rather than the cold efficiency in S102-2. .

[0094] Step S102-3: Calculation of heat transfer interface efficiency Heat transfer interface efficiency It is a dimensionless parameter that assesses the effectiveness of heat transfer from the motor to the housing and dissipation. Heat transfer interface assembly parameters include two categories: thermal contact surface parameters and heat dissipation structure parameters.

[0095] (1) Thermal contact surface parameters refer to the geometric and mechanical characteristic parameters of the heat transfer interface between the motor and the housing: Contact pressure (Unit: Pa): Normal clamping force between thermally contacting surfaces. Contact pressure directly affects the magnitude of contact thermal resistance. It can be obtained through methods including: direct measurement using a pressure sensor; or indirect calculation using assembly torque and connection stiffness.

[0096] Contact area (Unit: m²): The actual effective contact area of ​​the thermal contact surface. Methods of obtaining this include: measuring the projected area of ​​the contact surface using CAD software, and considering the actual contact ratio (usually...). Alternatively, the actual contact area can be measured using pressure-sensitive paper.

[0097] Surface roughness (Unit: μm): Surface roughness parameter of the thermal contact surface. Surface roughness affects the microscopic distribution of contact thermal resistance. It can be obtained by measuring with a roughness tester or by referring to the manufacturing process specifications.

[0098] (2) Heat dissipation structural parameters refer to the geometric and operational parameters of the heat dissipation elements on the casing: Number of heat sinks (Dimensionless): Total number of heat sinks on the casing. Obtained by directly counting the number of heat sinks in the casing design.

[0099] Heatsink height (Unit: m): Vertical height of the heat sink. Obtained by: CAD measurement or caliper measurement.

[0100] Heatsink width (Unit: m): Width of the heat sink in the airflow direction. Obtained by: CAD measurement or caliper measurement.

[0101] Heat sink thickness (Unit: m): Thickness of the heat sink in the width direction. Obtained by: CAD measurement or measurement with vernier calipers.

[0102] Heatsink spacing (Unit: m): Spacing between adjacent heat sinks. Obtained by: CAD measurement or caliper measurement.

[0103] Preset fan speed (Unit: RPM): Motor speed driving the cooling fan. Obtained from the fan datasheet or control system.

[0104] Rated heat load (Unit: W): The heat output of the motor under rated operating conditions. Obtained from the motor datasheet; or measured through a loss test.

[0105] Vibration can affect the effective contact pressure between thermal contact surfaces. When the vibration direction is aligned with the normal direction of the contact surface, the vibration load will dynamically superimpose on the static contact pressure; when the vibration direction is aligned with the tangential direction of the contact surface, the vibration may cause micro-slippage of the contact surface, reducing the effective contact pressure.

[0106] The formula for calculating the vibration-corrected contact pressure coefficient is:

[0107] in The effective contact pressure under vibration conditions (unit: Pa).

[0108] Calculation of effective contact pressure:

[0109] in The vibration contact pressure attenuation coefficient (dimensionless) typically ranges from [value missing]. This can be determined through vibration contact testing.

[0110] The physical mechanisms by which vibration reduces contact pressure include: the additional inertial force from vibration superimposed on the static pressure, leading to a decrease in effective clamping force; vibration causing micro-slippage on the contact surface, reducing the number of actual contact micro-spots; and vibration accelerating surface wear, altering the surface morphology, and thus affecting the contact pressure distribution. The proportional form is modified to ensure dimensional consistency (pressure multiplied by a dimensionless proportionality factor).

[0111] Vibration affects heat dissipation structures in two ways: firstly, it may enhance air turbulence and strengthen convective heat transfer; secondly, it may cause the relative motion between the heat sink and the air to deviate from the optimal direction, reducing heat transfer efficiency.

[0112] The formula for calculating the vibration-corrected heat dissipation efficiency coefficient is as follows:

[0113] in The convective heat transfer coefficient under vibration conditions (unit: W / (m²·K)). This is the baseline convective heat transfer coefficient under vibration-free conditions.

[0114] (1) Reference convective heat transfer coefficient Calculation For forced air cooling structures, the reference convective heat transfer coefficient is calculated based on the standard convective heat transfer criterion equation:

[0115] in: The thermal conductivity of air (unit: W / (m·K)) is taken as the value at room temperature and pressure. W / (m·K); The characteristic length (in meters) is uniformly taken as the spacing between heat sinks. ; The Nusselt number is calculated based on the empirical criterion equation for laminar flow in a parallel flat plate channel:

[0116] in: It is the Reynolds number; air kinematic viscosity (at room temperature and pressure) m² / s); is the Prandtl number for air (dimensionless); The wind speed is the face speed (in m / s).

[0117] (2) Headwind speed Calculation The oncoming wind speed is determined by the fan airflow and the cross-sectional area of ​​the air duct:

[0118] in: The volumetric flow rate of the fan (unit: m³ / s); The fan flow coefficient (unit: m³ / (min·RPM)) is defined as the flow rate per minute corresponding to each RPM. Fan speed (in RPM); This represents the cross-sectional area of ​​the air duct (in m²); dividing by 60 is to convert RPM to revolutions per second (RPS).

[0119] In the above formula, The unit is m³ / (min·RPM), which means "the flow rate in cubic meters per RPM per minute". When the unit is RPM, The unit is m³ / min, which needs to be divided by 60 to convert to m³ / s.

[0120] (3) Vibration-corrected convective heat transfer coefficient Calculation Vibration produces additional disturbance effects on airflow. The formula for calculating the vibration-corrected convective heat transfer coefficient is as follows:

[0121] in The vibration heat dissipation enhancement coefficient (dimensionless) typically ranges from [value missing]. This reflects the enhancing effect of vibration on boundary layer disturbance.

[0122] Vibration has a dual effect on convective heat transfer—moderate vibration enhances turbulence and can improve the heat transfer coefficient, but excessive vibration may disrupt the laminar boundary layer, leading to deterioration of heat transfer. The above formula applies to scenarios with low to medium vibration intensities. For scenarios with high vibration intensity, nonlinear corrections should be introduced.

[0123] Based on the combined parameters of the thermal contact surface and the heat dissipation structure, the formula for calculating the heat transfer interface efficiency is as follows:

[0124] in This represents the actual transferable heat (in W). Rated heat load (in W).

[0125] Actual heat transfer It consists of the following components:

[0126] (1) Contact thermal conductivity component

[0127] Heat is transferred through thermal contact surfaces, primarily via contact conduction. The formula for calculating contact conduction is:

[0128] in: This represents the temperature difference between the motor and the housing (in K). ; The thermal resistance of the interface material (if thermal grease or gasket is present) is expressed in K / W. Contact thermal resistance, in K / W.

[0129] Contact thermal resistance Calculation: Based on Yovanovich's contact thermal resistance theory, the formula for calculating contact thermal resistance is:

[0130] in: The contact thermal conductivity (unit: W / (m²·K)) is determined by experimental calibration or empirical formula; Nominal contact area (in m²); The vibration-corrected contact pressure coefficient (dimensionless).

[0131] Contact thermal conductivity With surface roughness Contact pressure and the thermal conductivity of the material The following empirical relationships can be used to determine the correlation:

[0132] in: The empirical coefficient of contact thermal conductivity (dimensionless); is the equivalent thermal conductivity of the interface material (unit: W / (m·K)); This is the surface roughness (in μm, which needs to be multiplied during calculation). Convert to m); The microhardness of the interface material (in Pa); The pressure index (dimensionless, usually taken as...) ).

[0133] (2) Convective heat transfer component

[0134] Heat is transferred to the surrounding air through the heat sink structure, primarily through forced convection heat transfer. The formula for calculating convective heat transfer is:

[0135] in: The vibration-corrected heat dissipation efficiency coefficient (dimensionless). The reference convective heat transfer coefficient (unit: W / (m²·K)); The shell temperature (in K or °C); Ambient temperature (in K or °C); This refers to the effective heat exchange area of ​​the heat sink (in m²).

[0136] Effective heat exchange area of ​​heat sink Calculation:

[0137] in: The number of heat sinks (dimensionless); This is the height of the heat sink (in meters). Width of the heat sink (in meters); This refers to the thickness of the heat sink (in meters).

[0138] It can be calculated using the following formula:

[0139] Step S102-4: Calculation of electromagnetic transmission interface efficiency Electromagnetic transmission interface efficiency It is a dimensionless parameter used to evaluate the effectiveness of electromagnetic shielding.

[0140] The assembly parameters of the electromagnetic transmission interface are mainly the electrical parameters of the lap joint.

[0141] Electrical parameters of the lap joint include: Number of overlap points (Dimensionless): Total number of electrical contact points between the motor and the housing. Contact points are a key structural element for ensuring electromagnetic shielding continuity; the number of contact points directly affects the number of shielding current paths. Acquisition method: Directly count the number of contact points specified in the assembly design.

[0142] Overlap area (Unit: m²): Effective contact area of ​​a single overlap point. The overlap area determines the contact resistance, thus affecting the shielding effectiveness. Methods of obtaining this information: Measure the projected area of ​​the overlap region using CAD; or determine it through actual measurement.

[0143] Overlap material: The electrical conductivity parameters of the material used at the overlap point. Different materials have different conductivity coefficients, directly affecting the contact resistance. Methods of obtaining this parameter: Refer to the bulk conductivity datasheet; or measure the conductivity of an actual sample using the four-probe method.

[0144] lap impedance (Unit: Ω): Initial contact resistance at the lap joint. Lap impedance is a core parameter for measuring lap quality; the lower the impedance, the better the shielding effectiveness. Acquisition method: Measure the contact resistance at the lap joint using a four-wire micro-ohmmeter; or infer the lap impedance through electromagnetic shielding effectiveness testing.

[0145] Rated electromagnetic shielding effectiveness (Unit: dB): Target electromagnetic shielding effectiveness of the motor-housing assembly under rated operating conditions. Acquisition method: Determined based on the electromagnetic compatibility requirements of the application scenario; or obtained from industry standards.

[0146] In some embodiments, the calculation of electromagnetic transmission interface efficiency based on vibration correction is as follows: (1) Calculation of vibration-corrected lap impedance coefficient Vibration can affect the effective contact between overlapping joints. When the vibration intensity is high, micro-slippage or gap changes may occur between the overlapping joints, leading to increased contact resistance. Furthermore, vibration can accelerate oxidation and corrosion on the surface of the overlapping joints, further deteriorating contact performance.

[0147] The formula for calculating the vibration-corrected lap impedance coefficient is as follows:

[0148] in This is the equivalent lap impedance under vibration conditions (in Ω). The initial contact resistance of the lap joint (in Ω).

[0149] Calculation of equivalent lap impedance under vibration conditions:

[0150] in This is the vibration lap impedance amplification factor (dimensionless), and its value range is typically [value range missing]. It can be determined through vibration contact resistance testing.

[0151] The physical mechanisms by which vibration increases lap resistance include: vibration causing micro-slippage at the contact surface, reducing the number of effective contact micro-spots; vibration accelerating the rupture and regeneration of the surface oxide film, altering the electrical properties of the contact interface; and vibration causing a temperature rise at the lap point, affecting the temperature characteristics of the contact resistance. The proportional form is corrected to ensure dimensional consistency (impedance multiplied by a dimensionless scaling factor).

[0152] (2) Calculation of single-point lap impedance The contact resistance at the lap joint is related to the lap area, the lap material, and the vibration correction factor. The formula for calculating the impedance of a single-point lap joint is:

[0153] in: This is the single-point lap impedance (in Ω). Equivalent contact resistivity (unit: Ω·m²) reflects the electrical characteristics of the contact interface. Its physical meaning is the equivalent impedance per unit area caused by the current contraction effect. Its value is related to the overlapping material, surface condition, and contact pressure, and can be determined by experimental testing. The overlap area is in m². The vibration correction lap impedance coefficient (dimensionless).

[0154] The above formula is a simplified expression based on Holm contact theory. Equivalent contact resistivity Unlike the bulk resistivity of a material, its value depends on the microstructure of the contact interface and the material pairing characteristics. Typical values ​​range from [value range missing]. The Ω·m² value can be determined by back-calculating after measuring the contact resistance of a standard sample using the four-probe method.

[0155] (3) Calculation of total lap impedance When multiple lap joints are connected in parallel, the formula for calculating the total lap impedance is:

[0156] in for The total lap impedance (in Ω) after connecting all lap points in parallel.

[0157] When multiple lap joints are connected in parallel, the total impedance is inversely proportional to the number of lap joints. Increasing the number of lap joints can effectively reduce the total lap impedance and improve electromagnetic shielding effectiveness.

[0158] (4) Calculation of electromagnetic transmission interface efficiency Electromagnetic transmission interface efficiency is defined as the ratio of actual shielding effectiveness to rated shielding effectiveness:

[0159] in The electromagnetic transmission interface efficiency (dimensionless) is the vibration-corrected value. Rated electromagnetic shielding effectiveness (in dB).

[0160] Calculation of actual shielding effectiveness: The relationship between electromagnetic shielding effectiveness and lap impedance can be expressed as:

[0161] in: For reference shielding effectiveness (in dB), the ideal overlap state is taken. The baseline value for shielding effectiveness under ( ) can be obtained through theoretical calculation or simulation; For the reference impedance (in Ω), a typical lap impedance value is usually taken as the normalization benchmark, typically taken as [value missing]. Ω (1mΩ); This reflects the logarithmic relationship between shielding effectiveness and impedance (based on transmission line theory).

[0162] The above formula is based on the logarithmic response characteristic of electromagnetic shielding—for every tenfold increase in lap impedance, the shielding effectiveness decreases by 20 dB. This relationship applies to low-frequency magnetic field shielding scenarios (typically below 30 MHz). Reference shielding effectiveness. and reference impedance The specific requirements should be determined based on the application scenario. For example, for household appliance motors, the shielding effectiveness is usually required to reach more than 20dB in the 30MHz~1GHz frequency band.

[0163] Comprehensive expression: Substituting the total lap impedance, we obtain an explicit expression for the vibration-corrected electromagnetic transmission interface efficiency:

[0164] The electromagnetic transmission interface efficiency calculation based on vibration-temperature coupling correction is further considered by taking into account the influence of temperature on the lap impedance, thus forming a vibration-temperature coupling correction electromagnetic transmission interface efficiency calculation.

[0165] (1) Obtaining temperature distribution parameters Temperature distribution parameters at the interface overlap point of electromagnetic transmission include: Overlap joint working temperature (Unit: °C, or Kelvin K): Temperature of the lap joint during actual operation. Methods of obtaining this temperature include: directly measuring the lap joint temperature using a thermocouple; obtaining the theoretical temperature value through thermal simulation calculations; or estimating it based on the motor temperature rise and ambient temperature.

[0166] Ambient temperature (Unit: °C, or Kelvin K): Ambient temperature of the motor. Method of obtaining: Measured with a thermometer; or obtained from the product specification sheet.

[0167] (2) Calculation of temperature difference and temperature-corrected lap resistance coefficient The effect of temperature on lap impedance is mainly reflected in two aspects: on the one hand, the increase in temperature will cause the thermal expansion of the metal material, which will change the contact pressure at the lap point; on the other hand, temperature will affect the oxide layer and contaminant state at the contact interface.

[0168] The temperature difference between the working temperature and the ambient temperature at the overlap point is:

[0169] The formula for calculating the temperature-corrected lap resistance coefficient is as follows:

[0170] in Temperature-corrected lap resistance coefficient (dimensionless). It is the temperature coefficient of contact resistance (unit: 1 / K, or 1 / ℃).

[0171] Temperature coefficient of contact resistance Definition and values: Temperature coefficient of contact resistance Defined as the relative rate of change of contact resistance per unit increase in temperature:

[0172] Its physical meaning is: the percentage increase in contact resistance for every 1°C increase in temperature.

[0173] Temperature coefficient of contact resistance The range of values ​​is usually 100. / ℃ (meaning that for every 1℃ increase in temperature, the contact resistance increases by 0.1%~1%), and this coefficient can be determined through temperature cycling contact resistance tests.

[0174] Different materials have different temperature coefficients when paired together—copper-copper contact has a lower temperature coefficient. / ℃), the temperature coefficient of aluminum-aluminum contact is relatively high ( / ℃), the temperature coefficient of steel-steel contact is between the two ( / ℃). This coefficient is also related to the surface treatment condition; the temperature coefficient of the lap joint for tin plating is usually lower than that for bare metal lap joints.

[0175] (3) Calculation of vibration-temperature coupling corrected lap impedance Taking into account the coupling effects of vibration and temperature, the coupling correction lap impedance coefficient is:

[0176] in The dimensionless lap impedance coefficient is used to correct the vibration-temperature coupling.

[0177] The effects of vibration and temperature on lap impedance are relatively independent and can be corrected by a product relationship. Vibration mainly affects the number and distribution of contact microspots, while temperature mainly affects the electrical properties of the material and the chemical state of the contact interface. When vibration and temperature act simultaneously, their coupling effect is negligible in engineering approximations.

[0178] (4) Calculation of the efficiency of the coupling-corrected electromagnetic transmission interface Substituting the coupling correction lap impedance coefficient, we obtain the formula for calculating the electromagnetic transmission interface efficiency:

[0179] in The electromagnetic transmission interface efficiency (dimensionless) is corrected for vibration-temperature coupling.

[0180] Calculation of actual shielding effectiveness with coupling correction:

[0181] in The total lap impedance after coupling correction:

[0182] Comprehensive expression:

[0183] In some embodiments, after determining the mechanical transmission interface efficiency, torque transmission interface efficiency, heat transmission interface efficiency, and electromagnetic transmission interface efficiency, the method further includes: obtaining the local dynamic stiffness of each key interface location on the housing; wherein each key interface location includes the keyway root, the heat dissipation fin root, and the overlap point location; using the main connecting surface of the housing as a reference location, calculating the dynamic displacement of each key interface location based on the dynamic displacement of the reference location and the local dynamic stiffness of each key interface location; and performing differential correction on the corresponding mechanical transmission interface efficiency, torque transmission interface efficiency, heat transmission interface efficiency, and electromagnetic transmission interface efficiency based on the dynamic displacement of each key interface location.

[0184] There are several critical interface locations on the motor housing, and the vibration response at these locations has a significant impact on the assembly quality. These critical interface locations are listed in Table 1 below: Table 1

[0185] Local dynamic stiffness refers to the ability of a structure to resist deformation at a specific location under dynamic loads. Unlike static stiffness, dynamic stiffness considers inertial and damping effects, and is defined as the complex ratio of the dynamic force amplitude to the dynamic displacement amplitude.

[0186] in: Local dynamic stiffness (in N / m) is the frequency. Complex functions; The magnitude of the dynamic force acting at this location (in N). This represents the dynamic displacement amplitude at that location (in meters).

[0187] Relationship between static stiffness and dynamic stiffness: Dynamic stiffness can be decomposed into static stiffness components and damping components:

[0188] in: Static stiffness (unit: N / m) can be obtained through static loading tests or finite element analysis; The damping loss factor (dimensionless) reflects the energy dissipation characteristics of the material. It is the imaginary unit.

[0189] The magnitude of the dynamic stiffness is When the damping loss factor When the dynamic stiffness is small, the amplitude of the dynamic stiffness is approximately equal to that of the static stiffness; when the damping is large, the amplitude of the dynamic stiffness is significantly greater than that of the static stiffness.

[0190] (3) Method for obtaining local dynamic stiffness at key interface locations The local dynamic stiffness at each key interface location can be obtained using the following methods: Method 1: Finite element simulation analysis: Establish a finite element model of the shell structure; apply a unit dynamic load to each key interface location and calculate the frequency response function (FRF); extract the dynamic stiffness value at each frequency of interest from the frequency response function.

[0191] Method 2: Modal testing: The shell structure is subjected to hammer excitation using a vibrator; the acceleration response at each key interface position is measured using an accelerometer; and the dynamic stiffness at each position is obtained through frequency response function analysis.

[0192] Method 3: Empirical Formula Estimation: For typical geometric structures, local dynamic stiffness can be estimated using empirical formulas. Keyway root (stress concentration area):

[0193] in This is the elastic modulus of the material (in Pa). This is the effective cross-sectional area at the root of the keyway (in m²). The characteristic length of the stress concentration region (in meters). The stress concentration factor (dimensionless) is usually taken as... .

[0194] Root of heat dissipation fins (thin-walled connection area):

[0195] in Moment of inertia of the section at the root of the heat sink fins (in meters) 4 ), This refers to the height of the heat sink fins (in meters). The constraint coefficient (dimensionless) reflects the degree of constraint between the fins and the main body of the shell.

[0196] Location of overlap:

[0197] in The contact stiffness of the lap joint (in N / m) can be determined through a contact stiffness test. This refers to the local stiffness of the shell structure around the joint (in N / m).

[0198] Then, the dynamic displacement of the key interface positions is calculated. (1) Determination of reference position The main connection surface of the housing is used as the reference position for dynamic displacement calculation. The main connection surface of the housing refers to the main connection area between the housing and the motor stator or end cover, which usually has a large mass and high structural rigidity.

[0199] Dynamic displacement of the main connecting surface of the shell The displacement can be obtained by: installing an accelerometer on the main connection surface to directly measure the acceleration response and then integrating it; or by obtaining the vibration velocity or acceleration amplitude of the main connection surface through a vibration testing system and then calculating the displacement amplitude through numerical integration.

[0200] (2) Introduction of mode shape function The response of a structure under dynamic excitation can be expressed as a superposition of modes. For simplified engineering analysis, mode shape functions can be introduced. To describe the relationship between the dynamic displacement at any position on the structure and the dynamic displacement at a reference position:

[0201] in: For any position in the structure The dynamic displacement amplitude at the location (in meters); The normalized mode shape function (dimensionless) describes the degree of vibration amplification or attenuation at this position relative to the reference position; The dynamic displacement amplitude (in meters) at the reference position.

[0202] (3) Determination of mode shape function at key interface location The mode shape function values ​​at each key interface location can be determined using the following method: Method 1: Modal analysis is performed on the shell structure to obtain the natural frequencies and mode shapes of the structure; the geometric coordinates of each key interface position are substituted into the mode shape function to calculate the mode shape function value; the mode shape value corresponding to the frequency of interest (usually the operating frequency or resonant frequency) is obtained.

[0203] Method 2: Obtaining the transfer function by experiment: Install an exciter or use hammer excitation at the reference position; install accelerometers at each key interface position and measure the transfer function; the amplitude ratio of the transfer function is the approximation of the mode shape function value at that frequency point.

[0204] Method 3: Simplified Estimation: For typical motor housing structures, simplified formulas can be used to estimate the mode shape function values: Keyway root (usually located in a stress concentration area, where vibration may be amplified):

[0205] in This is the vibration amplification factor (dimensionless) at the root of the keyway, and its value range is typically [value range missing]. That is, the vibration displacement at the root of the keyway may be 10% to 50% greater than that at the main connection surface.

[0206] The root of the heat sink fins (thin-walled structure, low natural frequency, which may lead to resonant amplification):

[0207] in The vibration response coefficient of the heat sink fins is dimensionless. This represents the natural frequency of the heat sink fins (in rad / s). When the excitation frequency is close to the natural frequency, the mode shape function value may increase significantly.

[0208] Location of the overlap point (depending on the specific location of the overlap point):

[0209] It can be determined through geometric positional relationships or experimental data.

[0210] (4) Calculation of dynamic displacement of key interface positions Based on the mode shape function, the formula for calculating the dynamic displacement at the key interface location is as follows:

[0211]

[0212]

[0213] in , , The values ​​represent the dynamic displacement amplitudes (in meters) at the keyway root, heat sink fin root, and overlap point.

[0214] (5) Calculation of vibration intensity at key interface locations Local vibration intensity at key interface locations Defined as the ratio of the dynamic displacement amplitude at that location to the reference value of the rated dynamic displacement:

[0215] in: The vibration intensity at the critical interface location is dimensionless. This represents the dynamic displacement amplitude at that location (in meters). The rated dynamic displacement reference value (in meters) is determined by the allowable stress of the shell material. and local stiffness at key interface locations Conversion confirmed:

[0216] in This refers to the effective load-bearing area at the critical interface location.

[0217] Therefore, the local vibration intensity Vibration intensity as defined in S101 They remain consistent in their physical nature, both being the normalized ratio of local vibration effect to local bearing capacity.

[0218] In engineering approximations, it is assumed that the ratio of local stiffness to effective bearing area at each critical interface location is similar to that at the reference location (i.e., ...). Then, the vibration intensity at each key interface location can be simplified to the product of the vibration intensity at the reference location and the mode shape function value:

[0219]

[0220]

[0221] Finally, interface efficiency differentiation corrections Differential correction refers to adjusting the local vibration intensity at each key interface location. Replaces the uniform vibration intensity in the S102 series Substituting the values ​​into the corresponding interface efficiency calculation formula, we obtain the corrected interface efficiency, as shown in Table 2 below: Table 2

[0222] For the mechanical transmission interface, the local vibration intensity at the root of the keyway is considered. Substituting into the efficiency calculation formula of S102-1, we obtain the corrected efficiency of the mechanical transmission interface:

[0223] in This is the function for calculating the efficiency of the mechanical transmission interface as defined in S102-1.

[0224] (3) Differentiation correction of torque transmission interface efficiency For the torque transmission interface, the local vibration intensity at the root of the keyway is considered. Substituting into the efficiency calculation formula of S102-2 or S102-3, we obtain the corrected torque transmission interface efficiency:

[0225] in This is the torque transmission interface efficiency calculation function defined in S102-2 or S102-3.

[0226] For the heat transfer interface, the local vibration intensity at the root of the heat sink fins is considered. Substituting into the efficiency calculation formula of S102-4, we obtain the corrected heat transfer interface efficiency:

[0227] in This is the function for calculating the efficiency of the heat transfer interface as defined in S102-4.

[0228] Note: The local dynamic stiffness at the root of the heat sink fins is usually low, and it may produce large dynamic displacements under vibration excitation. May be significantly larger than This leads to an underestimation of the efficiency of the heat transfer interface (the actual heat transfer performance may be better than the estimate).

[0229] For electromagnetic transmission interfaces, the local vibration intensity at the overlap point is considered. Substituting into the efficiency calculation formula of S102-5, we obtain the corrected electromagnetic transmission interface efficiency:

[0230] in This is the function for calculating the electromagnetic transfer interface efficiency as defined in S102-5.

[0231] The efficiency of each interface after differentiation correction can be summarized as follows:

[0232] in , For the first The mode shape function values ​​at key locations on the interface. For the first Efficiency calculation function for user interfaces.

[0233] Explanation of the correction effect: when At this time, the vibration intensity at the critical interface location is amplified, and the interface efficiency is underestimated; when At that time, the vibration intensity at the critical interface location was attenuated, and the interface efficiency was overestimated. when At that time, the vibration intensity at the critical interface location is the same as that at the reference location, and the correction effect is zero.

[0234] In some embodiments, the efficiency of the mechanical transmission interface is calculated. Torque transmission interface efficiency Heat transfer interface efficiency and electromagnetic transmission interface efficiency Then, determine whether the assembly quality is up to standard by following these steps: The first step is to calculate the overall assembly quality index. :

[0235] in: , , , These are the weighting coefficients for the efficiency of each interface, satisfying...

[0236] The value is determined based on the specific application scenario. For ducted fan propulsion systems, a typical value is... , , , .

[0237] The second step is to compare the overall assembly quality index with the preset pass threshold: when At that time, the assembly quality is deemed acceptable; when If so, the assembly quality is deemed unqualified.

[0238] in The preset acceptable threshold (dimensionless) is determined based on product reliability requirements, with a typical range of values. .

[0239] The third step is to locate the weak points in the assemblies that are determined to be unqualified based on the efficiency values ​​of each component: like or If the value is too low, check the tightness and fit accuracy of the mechanical connection interface. like If the pressure is too low, check the contact pressure of the thermal contact surface and the heat dissipation structure. like The value is too low. Check the contact condition and quantity of the overlap points.

[0240] like Figure 2 As shown in the figure, this is a schematic diagram of an assembly method system for coordinated weight reduction of a ducted fan motor and housing according to an embodiment of this application. The system includes: The vibration intensity calculation module 201 is used to obtain the assembly design parameters of the motor and the housing under the condition that the overall assembly weight reduction constraint is met, and to calculate the vibration intensity based on the assembly design parameters. The assembly design parameters include the motor rotor mass, the motor rotor angular velocity, the eccentricity of the motor rotor center of mass relative to the rotation axis, the eccentricity mass coefficient, the vibration transmission path efficiency, the effective bearing area of ​​the housing, and the allowable stress of the housing material. The assembly process inspection module 202 is used to determine whether the assembly quality of the motor and the housing is qualified based on the vibration intensity and the acquired assembly process parameters.

[0241] The assembly method system for coordinated weight reduction of the motor and housing of a ducted fan according to the embodiments of this application can correspond to the execution of the method described in the embodiments of this application, and the other operations and / or functions of each module / unit of the assembly method system for coordinated weight reduction of the motor and housing of a ducted fan are respectively for realizing Figure 1 For the sake of brevity, the corresponding processes of each method in the illustrated embodiments will not be described in detail here.

[0242] The descriptions of the processes or structures corresponding to the above figures each have their own emphasis. For parts of a process or structure that are not described in detail, please refer to the relevant descriptions of other processes or structures.

[0243] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions within the technical scope disclosed in this application should be covered within the scope of protection of this application.

Claims

1. A method for synergistic weight reduction of the motor and housing in a ducted fan assembly, characterized in that, The method includes: Under the condition that the weight reduction constraint of the overall assembly is met, the assembly design parameters of the motor and the housing are obtained, and the vibration intensity is calculated based on the assembly design parameters; wherein, the assembly design parameters include the motor rotor mass, the motor rotor angular velocity, the eccentricity of the motor rotor center of mass relative to the axis of rotation, the eccentricity mass coefficient, the vibration transmission path efficiency, the effective bearing area of ​​the housing, and the allowable stress of the housing material; Based on the vibration intensity and the acquired assembly process parameters, it is determined whether the assembly quality of the motor and the housing is qualified.

2. The method according to claim 1, characterized in that, The assembly process parameters include torque transmission interface assembly parameters, heat transmission interface assembly parameters, electromagnetic transmission interface assembly parameters, and the eccentricity between the motor rotor and the housing. The determination of whether the assembly quality of the motor and the housing is qualified based on the vibration intensity includes: Based on the eccentricity and the vibration intensity, calculate the efficiency of the mechanical transmission interface; The torque transmission interface efficiency is calculated based on the assembly parameters of the torque transmission interface and the vibration intensity. The efficiency of the heat transfer interface is calculated based on the assembly parameters of the heat transfer interface and the vibration intensity. The electromagnetic transmission interface efficiency is calculated based on the assembly parameters of the electromagnetic transmission interface and the vibration intensity. Calculate the comprehensive assembly quality index; wherein, the comprehensive assembly quality index is the weighted average of the mechanical transmission interface efficiency, the torque transmission interface efficiency, the heat transmission interface efficiency, and the electromagnetic transmission interface efficiency; When the overall assembly quality index is greater than or equal to the preset qualified threshold, the assembly quality of the motor and the housing is determined to be qualified; otherwise, the assembly quality is determined to be unqualified.

3. The method as described in claim 2, characterized in that, The calculation of the mechanical transmission interface efficiency based on the eccentricity and the vibration intensity includes: Using the eccentricity and vibration intensity as input parameters, the mechanical transmission interface efficiency is calculated based on the pre-established mapping relationship between mechanical transmission efficiency and eccentricity and vibration intensity.

4. The method as described in claim 2, characterized in that, The torque transmission interface assembly parameters include the taper angle of the tapered connection structure, the interference fit of the hub connection structure, the number of keys in the keyed connection structure, and the basic friction coefficient of the connection interface. The calculation of torque transmission interface efficiency based on the torque transmission interface assembly parameters and the vibration intensity includes: Calculate the vibration-corrected friction coefficient based on the vibration intensity and the basic friction coefficient; The torque transmission interface efficiency is calculated based on the vibration-corrected friction coefficient, the taper angle, the interference fit, the number of keys, and the rated torque parameters.

5. The method as described in claim 4, characterized in that, The step of calculating the torque transmission interface efficiency based on the vibration-corrected friction coefficient, the taper angle, the interference fit, the number of keys, and the rated torque parameters includes: Obtain the temperature parameters of the housing portion and the motor shaft portion that mate with the tapered connection structure; The axial thermal deformation difference is calculated based on the temperature parameters of the housing and the motor shaft. The thermal preload relaxation amount of the tapered connection structure is calculated based on the axial thermal deformation difference, and the initial radial clamping force of the tapered connection structure is corrected based on the thermal preload relaxation amount to obtain the thermally corrected radial clamping force. The torque transmission interface efficiency is calculated based on the vibration-corrected friction coefficient, the thermally corrected radial clamping force, the taper angle, the interference fit, the number of keys, and the rated torque parameters.

6. The method as described in claim 4, characterized in that, The heat transfer interface assembly parameters include thermal contact surface parameters and heat dissipation structure parameters; wherein, the thermal contact surface parameters include contact pressure, contact area and surface roughness, and the heat dissipation structure parameters include the number of heat sinks, heat sink height, heat sink spacing and preset fan speed. The calculation of the heat transfer interface efficiency based on the heat transfer interface assembly parameters and the vibration intensity includes: Calculate the vibration-corrected contact pressure coefficient based on the vibration intensity and the contact pressure; Based on the vibration intensity and the preset fan speed, the vibration-corrected heat dissipation efficiency coefficient is calculated; The heat transfer interface efficiency is calculated based on the vibration-corrected contact pressure coefficient, the vibration-corrected heat dissipation efficiency coefficient, the contact area, the surface roughness, the number of heat sinks, the height of the heat sinks, the spacing between the heat sinks, and the rated heat load parameters.

7. The method as described in claim 6, characterized in that, The assembly parameters of the electromagnetic transmission interface include the electrical parameters of the overlap point; wherein, the electrical parameters of the overlap point include the number of overlap points, the overlap area, the overlap material, and the overlap impedance; The calculation of the electromagnetic transmission interface efficiency based on the assembly parameters of the electromagnetic transmission interface and the vibration intensity includes: Based on the vibration intensity and the lap impedance, calculate the vibration-corrected lap impedance coefficient; The electromagnetic transmission interface efficiency is calculated based on the vibration-corrected lap impedance coefficient, the number of lap points, the lap area, the lap material, and the rated electromagnetic shielding effectiveness parameters.

8. The method as described in claim 7, characterized in that, The calculation of the electromagnetic transmission interface efficiency based on the vibration-corrected lap impedance coefficient, the number of lap points, the lap area, the lap material, and the rated electromagnetic shielding effectiveness parameters includes: Obtain the temperature distribution parameters at the electromagnetic transmission interface overlap point, and calculate the temperature difference between the working temperature of the overlap point and the ambient temperature based on the temperature distribution parameters. Based on the temperature difference and the preset contact resistance temperature coefficient, the temperature-corrected lap impedance coefficient is calculated. Based on the vibration-corrected lap impedance coefficient and the temperature-corrected lap impedance coefficient, combined with the number of lap points, the lap area, the lap material, and the rated electromagnetic shielding effectiveness parameters, the electromagnetic transmission interface efficiency is calculated.

9. The method as described in claim 7, characterized in that, After determining the mechanical transmission interface efficiency, the torque transmission interface efficiency, the thermal transmission interface efficiency, and the electromagnetic transmission interface efficiency, the method further includes: The local dynamic stiffness of each key interface location on the housing is obtained; wherein, each key interface location includes the root of the keyway, the root of the heat dissipation fin, and the overlapping point location; Using the main connecting surface of the shell as a reference position, the dynamic displacement of each of the key interface positions is calculated based on the dynamic displacement of the reference position and the local dynamic stiffness of each key interface position. Based on the dynamic displacement of each of the key interface positions, the efficiency of the corresponding mechanical transmission interface, torque transmission interface, heat transmission interface, and electromagnetic transmission interface is differentiated and corrected.

10. An assembly system for coordinated weight reduction of the motor and housing of a ducted fan, characterized in that, The system includes: The vibration intensity calculation module is used to obtain the assembly design parameters of the motor and the housing under the condition that the overall assembly weight reduction constraint is met, and to calculate the vibration intensity based on the assembly design parameters; wherein, the assembly design parameters include the motor rotor mass, the motor rotor angular velocity, the eccentricity of the motor rotor center of mass relative to the rotation axis, the eccentricity mass coefficient, the vibration transmission path efficiency, the effective bearing area of ​​the housing, and the allowable stress of the housing material; The assembly process inspection module is used to determine whether the assembly quality of the motor and the housing is qualified based on the vibration intensity and the obtained assembly process parameters.

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