Method for obtaining temperature rise of planetary reducer

Abstract

The application discloses a kind of temperature rise condition acquisition methods of planetary reducer, the heat generation and heat transfer mode of planetary gear and sun gear meshing is characterized by calculating equivalent thermal resistance, temperature rise prediction is placed in the design stage of reducer, the prediction accuracy and efficiency of temperature field and velocity field of reducer are improved, and the design cost and design cycle of reducer are reduced and shortened.Simultaneously this is separated simulation processing to planetary gear and sun gear, the heat generation and heat transfer solution of planetary gear and sun gear meshing is characterized by using the equivalent thermal resistance of planetary gear and the equivalent thermal resistance of sun gear respectively, overcomes the deficiency that calculation accuracy is poor, calculation is large, temperature rise prediction period is long in the problem of considering gear meshing of traditional finite element analysis method, with convenient calculation, accurate calculation, can compare the temperature field and velocity field of reducer accurately calculated, temperature rise prediction is placed in the design stage of reducer, reduce cost, can be widely applied in the technical effect of reducer technical field.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of reducer design, and particularly relates to a method for obtaining temperature rise of a planetary reducer. BACKGROUND

[0002] In previous research, if the meshing of the planetary gear and the sun gear is directly simulated, the calculation amount of two-dimensional and three-dimensional is large, the meshing of the gear needs to be considered, the method of dynamic mesh is applied, the overall calculation amount is large, and the calculation precision is poor; therefore, the temperature rise of the reducer is often obtained by testing the reducer prototype on the test bench; this method increases the design cost and period of the reducer. SUMMARY

[0003] Therefore, the present application is to overcome the defects of increased design cost and long period caused by the temperature rise evaluation of the reducer in the prior art, and to provide a method for obtaining the temperature rise of a planetary reducer.

[0004] To solve the above technical problems, the technical scheme of the present application is as follows:

[0005] A method for obtaining the temperature rise of a planetary reducer based on a finite element simulation analysis platform, comprising the following steps:

[0006] Constructing a physical model of the planetary gear according to the actual geometric parameters of the planetary gear, and constructing a physical model of the sun gear according to the actual geometric parameters of the sun gear;

[0007] Setting the finite element parameters of the planetary gear to obtain the temperature field of the planetary gear, and setting the finite element parameters of the sun gear to obtain the temperature field of the sun gear;

[0008] Calculating the equivalent thermal resistance of the planetary gear according to the temperature field, surface area parameters and heat source of the planetary gear, and calculating the equivalent thermal resistance of the sun gear according to the temperature field, surface area parameters and heat source of the sun gear;

[0009] Constructing a physical model of the reducer according to the actual geometric parameters of the reducer;

[0010] Setting the finite element parameters of the reducer, and applying the equivalent thermal resistance of the sun gear and the equivalent thermal resistance of the planetary gear to the sun gear and the planetary gear in the physical model of the reducer respectively, to construct a finite element model of the reducer;

[0011] According to the finite element model of the reducer, the temperature and speed distribution field of the reducer are obtained.

[0012] According to some embodiments of the present application, the step of setting finite element parameters of the planetary gear to obtain a temperature field of the planetary gear comprises: setting finite element parameters of the planetary gear to build a finite element model of the planetary gear; setting boundary conditions in the finite element model of the planetary gear and solving to obtain the temperature field of the planetary gear.

[0013] The step of setting finite element parameters of the sun gear to obtain a temperature field of the sun gear comprises: setting finite element parameters of the sun gear to build a finite element model of the sun gear; setting boundary conditions in the finite element model of the sun gear and solving to obtain the temperature field of the sun gear.

[0014] According to some embodiments of the present application, the step of setting finite element parameters of the planetary gear to build a finite element model of the planetary gear comprises:

[0015] unit selection and material setting of the planetary gear in the finite element model;

[0016] meshing of the planetary gear in the finite element model;

[0017] setting of thermal load of the planetary gear in the finite element model to build the finite element model of the planetary gear;

[0018] The step of setting finite element parameters of the sun gear to build a finite element model of the sun gear comprises:

[0019] unit selection and material setting of the sun gear in the finite element model;

[0020] meshing of the sun gear in the finite element model;

[0021] setting of thermal load of the sun gear in the finite element model to build the finite element model of the sun gear.

[0022] According to some embodiments of the present application, the unit selection and material setting of the planetary gear in the finite element model specifically comprises: defining the planetary gear according to the specific heat capacity, density and thermal conductivity of the actual material of the planetary gear; setting a fluid domain close to the planetary gear as a rotating domain and setting a fluid domain far from the planetary gear as a stationary domain;

[0023] The unit selection and material setting of the sun gear in the finite element model specifically comprises: defining the sun gear according to the specific heat capacity, density and thermal conductivity of the actual material of the sun gear; setting a fluid domain close to the sun gear as a rotating domain and setting a fluid domain far from the sun gear as a stationary domain.

[0024] The grid division of the planetary gear in the finite element model is specifically that the geometric model of the planetary gear is divided into a tetrahedron type grid scheme.

[0025] The grid division of the sun gear in the finite element model is specifically that the geometric model of the sun gear is divided into a tetrahedron type grid scheme.

[0026] The setting of the thermal load of the planetary gear in the finite element model is specifically that the surface heat source of the planetary gear and the volume heat source of the planetary bearing are added to the planetary gear surface and the planetary bearing, respectively.

[0027] The setting of the thermal load of the sun gear in the finite element model is specifically that the surface heat source of the sun gear and the volume heat source of the sun bearing are added to the sun gear surface and the sun bearing, respectively.

[0028] According to some embodiments of the present application, the setting of the boundary condition and the solving in the finite element model of the planetary gear to obtain the temperature field of the planetary gear is specifically that the corresponding rotating speed of the planetary gear and the initial temperature of the surrounding lubricating oil are set, and the finite element model of the planetary gear is calculated to obtain the temperature field and the speed field distribution result of the planetary gear.

[0029] The setting of the boundary condition and the solving in the finite element model of the sun gear to obtain the temperature field of the sun gear is specifically that the corresponding rotating speed of the sun gear and the initial temperature of the surrounding lubricating oil are set, and the finite element model of the sun gear is calculated to obtain the temperature field and the speed field distribution result of the sun gear.

[0030] According to some embodiments of the present application, the step of calculating the equivalent thermal resistance of the planetary gear according to the temperature field, the surface area parameter and the heat source of the planetary gear comprises: calculating the convective surface heat transfer coefficient of the planetary gear according to the temperature field, the surface area parameter and the heat source of the planetary gear, simplifying the structure of the planetary gear, and calculating the equivalent thermal resistance of the simplified planetary gear according to the convective surface heat transfer coefficient of the planetary gear.

[0031] The step of calculating the equivalent thermal resistance of the sun gear according to the temperature field, the surface area parameter and the heat source of the sun gear comprises: calculating the convective surface heat transfer coefficient of the planetary gear according to the temperature field, the surface area parameter and the heat source of the planetary gear, simplifying the structure of the sun gear, and calculating the equivalent thermal resistance of the simplified sun gear according to the convective surface heat transfer coefficient of the sun gear.

[0032] According to some embodiments of the present application, the calculation formula of the convective surface heat transfer coefficient of the planetary gear according to the temperature field, the surface area parameter and the heat source of the planetary gear and the calculation formula of the convective surface heat transfer coefficient of the sun gear according to the temperature field, the surface area parameter and the heat source of the sun gear are as follows:

[0033]

[0034] wherein h is the convective surface heat transfer coefficient, Q is the total power loss of the planetary gear or the sun gear, A is the effective heat transfer area of the outer circumferential surface of the planetary gear or the sun gear, t is the wall surface temperature of the planetary gear or the sun gear, t is the average temperature of the gear wall surface, t is the average temperature of the lubricating oil fluid in contact with the interface of the channel wall surface, and t is the average temperature of the lubricating oil fluid in contact with the interface of the channel wall surface. w wherein h is the convective surface heat transfer coefficient, Q is the total power loss of the planetary gear or the sun gear, A is the effective heat transfer area of the outer circumferential surface of the planetary gear or the sun gear, t is the wall surface temperature of the planetary gear or the sun gear, t is the average temperature of the gear wall surface, t is the average temperature of the lubricating oil fluid in contact with the interface of the channel wall surface, and t is the average temperature of the lubricating oil fluid in contact with the interface of the channel wall surface. f wherein h is the convective surface heat transfer coefficient, Q is the total power loss of the planetary gear or the sun gear, A is the effective heat transfer area of the outer circumferential surface of the planetary gear or the sun gear, t is the wall surface temperature of the planetary gear or the sun gear, t is the average temperature of the gear wall surface, t is the average temperature of the lubricating oil fluid in contact with the interface of the channel wall surface, and t is the average temperature of the lubricating oil fluid in contact with the interface of the channel wall surface.

[0035] The calculation formula of the equivalent thermal resistance of the structurally simplified planetary gear according to the convective surface heat transfer coefficient of the planetary gear and the equivalent thermal resistance of the structurally simplified sun gear according to the convective surface heat transfer coefficient of the sun gear is as follows:

[0036]

[0037] wherein R is the equivalent thermal resistance, h is the convective surface heat transfer coefficient, A is the effective heat transfer area of the outer circumferential surface of the planetary gear or the sun gear, and A' is the outer circumferential surface area of the structurally simplified planetary gear or the sun gear.

[0038] According to some embodiments of the present application, the structural simplification of the planetary gear specifically refers to simplifying the geometric model of the planetary gear into a cylinder.

[0039] The structural simplification of the sun gear specifically refers to simplifying the geometric model of the sun gear into a cylinder.

[0040] According to some embodiments of the present application, the step of setting the finite element parameters of the speed reducer and applying the equivalent thermal resistance of the sun gear and the equivalent thermal resistance of the planetary gear to the sun gear and the planetary gear in the physical model of the speed reducer, respectively, to construct the finite element model of the speed reducer includes:

[0041] selecting units and setting materials for all components in the physical model of the speed reducer in the finite element model;

[0042] dividing the mesh for all components in the physical model of the speed reducer in the finite element model;

[0043] setting the heat load of each heat generating component in the physical model of the speed reducer in the finite element model and applying the equivalent thermal resistance of the sun gear and the equivalent thermal resistance of the planetary gear to the surface of the sun gear and the planetary gear in the physical model of the speed reducer, respectively, to construct the finite element model of the speed reducer.

[0044] According to some embodiments of the present application, the unit selection and material setting of all components in the physical model of the reducer in the finite element model are specifically: defining each component according to the specific heat capacity, density and thermal conductivity of all components in the physical model of the reducer, and setting the internal fluid domain of the reducer as a rotating domain;

[0045] The meshing of all components in the physical model of the reducer in the finite element model is specifically: dividing the geometric model of the reducer into a tetrahedral type mesh scheme;

[0046] The thermal load setting of each heat generating component in the physical model of the reducer in the finite element model, except for the planetary gear and the sun gear, is specifically: adding a body heat source to all heat generating components including the planetary gear, the sun gear and the bearing according to the thermal load of the reducer.

[0047] According to some embodiments of the present application, the step of obtaining the temperature and speed distribution field of the reducer according to the finite element model of the reducer includes: setting and solving the boundary conditions in the finite element model of the reducer to obtain the temperature and speed distribution field of the reducer.

[0048] According to some embodiments of the present application, in the finite element model of the reducer, the internal fluid domain of the gear cavity is defined as a rotating domain model, and the rotating speed is defined; the inlet and outlet boundaries of the reducer are set; the finite element model of the reducer is calculated to obtain the temperature and speed distribution field of the reducer.

[0049] The technical scheme of the present application has the following advantages:

[0050] 1. The method for obtaining the temperature rise of the planetary reducer provided by the present application characterizes the heat generation and heat transfer mode of the meshing of the planetary gear and the sun gear by calculating the equivalent thermal resistance, places the temperature rise prediction in the design stage of the reducer, improves the prediction accuracy and efficiency of the temperature field and speed field of the reducer, and reduces and shortens the design cost and design cycle of the reducer. At the same time, the evaluation method avoids using dynamic mesh calculation through finite element model simulation method, reduces the calculation amount of the three-dimensional model, further improves the calculation accuracy, and shortens the calculation time.

[0051] 2. The method for obtaining the temperature rise of the planetary reducer provided by the present application simplifies the structure of the physical model of the planetary gear or the sun gear to facilitate the meshing of the planetary gear or the sun gear, simplifies the physical model of the planetary gear or the sun gear into a symmetric body, reduces the number of meshing, further reduces the calculation amount of the three-dimensional model, further improves the calculation accuracy, and shortens the calculation time. BRIEF DESCRIPTION OF DRAWINGS

[0052] In order to more clearly illustrate the technical solutions in the specific embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the specific embodiments or prior art description. Obviously, the drawings described below are only some embodiments of the present application, and the ordinary skilled in the art can obtain other drawings according to these drawings without any creative effort.

[0053] Figure 1 The implementation flowchart of the temperature rise condition obtaining method of the planetary reducer provided by the embodiment of the present application is shown in the figure.

[0054] Figure 2 The simplified schematic diagram of the planetary gear or sun gear structure of the present application is shown in the figure.

[0055] Figure 3 The temperature distribution diagram of the sun gear of the present application is shown in the figure.

[0056] Figure 4 The speed distribution diagram of the lubricating oil in the inner cavity of the reducer of the present application is shown in the figure. DETAILED DESCRIPTION

[0057] The technical solutions of the present application will be described clearly and completely below with reference to the drawings. Obviously, the described embodiments are only some of the embodiments of the present application, not all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by the ordinary skilled in the art without any creative effort are within the scope of protection of the present application.

[0058] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation of the present application. In addition, the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0059] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For the ordinary skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0060] In addition, the technical features involved in the different embodiments of the application described below can be combined with each other as long as they do not conflict with each other.

[0061] The finite element simulation analysis platform used in the application is Ansys CFX;

[0062] As shown in Figure 1 Based on the Ansys CFX simulation analysis software, the application proposes a method for obtaining the temperature rise condition of a planetary reducer, which comprises the following steps:

[0063] S100, a physical model of the planetary gear is constructed according to the actual geometric parameters of the planetary gear, and a physical model of the sun gear is constructed according to the actual geometric parameters of the sun gear.

[0064] Specifically, the geometric parameters of the planetary gear and the sun gear include the number of teeth, the module, the pitch diameter, the pressure angle, the tooth height and the tooth thickness. According to the determination and calculation of the above parameters of the planetary gear or the sun gear, the physical model of the planetary gear or the sun gear is constructed in the modeling software or directly in Ansys, and the constructed physical model of the planetary gear or the sun gear is imported into Ansys CFX.

[0065] S200, the finite element parameters of the planetary gear are set in Ansys CFX to obtain the temperature field of the planetary gear; the finite element parameters of the sun gear are set in Ansys CFX to obtain the temperature field of the sun gear.

[0066] Specifically, in the step of S200:

[0067] The finite element parameters of the planetary gear are set in Ansys CFX to obtain the temperature field of the planetary gear, which comprises the following steps:

[0068] S210a, the finite element parameters of the planetary gear are set in Ansys CFX to construct the Ansys CFX finite element model of the planetary gear.

[0069] The step of S210a comprises:

[0070] S211a, unit selection and material setting are performed on the planetary gear in the Ansys CFX finite element model;

[0071] S212a, meshing is performed on the planetary gear in the Ansys CFX finite element model;

[0072] S213a, the thermal load of the planetary gear is set in the Ansys CFX finite element model to construct the Ansys CFX finite element model of the planetary gear.

[0073] The step of S211a is specifically: defining the planetary gear according to the specific heat capacity, density and thermal conductivity of the actual material of the planetary gear; setting the fluid domain close to the planetary gear as a rotating domain and setting the fluid domain far from the planetary gear as a stationary domain. The step of S212a is specifically: dividing the geometric model of the planetary gear into a tetrahedral type grid scheme using Fluent Meshing and importing it into CFX-Pre. The step of S213a is specifically: adding the surface heat source of the planetary gear and the volume heat source of the planetary bearing to the surface of the planetary gear and the bearing of the planetary gear respectively.

[0074] Since only rotating motion is supported in Ansys CFX, translational motion cannot be supported, so the calculation of the rotating domain can be performed in Ansys CFX. When the calculation region of the planetary gear and the sun gear is set, the angular velocity of rotation and the rotating shaft are set, the fluid domain close to the planetary gear and the fluid domain close to the sun gear are both set as rotating domains, and the Coriolis force and centripetal force of the fluid domain around the planetary gear and the sun gear are mainly calculated.

[0075] When the planetary gear meshes with the sun gear, heat is transferred on the contact surface, so the surface heat source is added to the surface of the planetary gear and the sun gear, and the bearing is used as the rotating shaft, so the bearing of the planetary gear and the bearing of the sun gear are both set as volume heat sources.

[0076] The commonly used grid scheme is tetrahedral grid type and hexahedral grid type. The advantage of hexahedral grid is that the calculation scale is relatively small and is mainly used in dynamic analysis. However, hexahedral grid needs more time for geometric simplification and cutting, and it takes a long time to generate the grid. The tetrahedral grid has good adaptability to complex geometry and is mainly used for free grid division, and it takes a short time to generate the grid. Using tetrahedral grid type can shorten the grid division time and improve the efficiency. In addition, the grid is easy to change with the change of external CAD, and using hexahedral grid can easily lead to excessive workload, and tetrahedral grid can automatically realize grid encryption and reduce workload.

[0077] S220a, setting boundary conditions and solving in the Ansys CFX finite element model of the planetary gear to obtain the temperature field of the planetary gear.

[0078] The step of S220a is specifically: setting the corresponding rotating speed of the planetary gear and the initial temperature of the surrounding lubricating oil, inputting the Ansys CFX finite element model of the planetary gear into CFX Solver for calculation to obtain the temperature field and velocity field distribution results of the planetary gear.

[0079] The boundary conditions of the model are defined in Ansys CFX mainly in two steps, one is to define the position and type of the model, and the second is to specify the boundary numerical value. The position and type of the boundary have been defined when the grid is divided, so the position of the inlet and outlet of the model and the position of the wall surface partition need to be clearly divided when the grid is divided. In the present application, the temperature partition of the wall surface of the planetary gear and the sun gear needs to be divided to avoid the model from being unable to be distinguished when being imported into Ansys CFX. The definition of the boundary numerical value includes defining the fluid velocity or pressure value. In Ansys CFX, when the inlet flow rate is defined, backflow is allowed to occur, and when the inlet pressure value of the fluid is defined, backflow is not allowed to occur. In some embodiments of the present application, the initial velocity of the lubricating oil is defined. The definition of the outlet flow rate or pressure value is the same. When it cannot be determined whether the backflow exists at the inlet boundary or the outlet boundary, the free boundary can be selected in Ansys CFX.

[0080] Specifically, in the step of S200:

[0081] The step of setting the finite element parameters of the sun gear in Ansys CFX to obtain the temperature field of the sun gear includes:

[0082] S210b, setting the finite element parameters of the sun gear in Ansys CFX to build an Ansys CFX finite element model of the sun gear.

[0083] The step of S210b includes:

[0084] S211b, selecting the unit and setting the material of the sun gear in the Ansys CFX finite element model;

[0085] S212b, meshing the sun gear in the Ansys CFX finite element model;

[0086] S213b, setting the thermal load of the sun gear in the Ansys CFX finite element model to build an Ansys CFX finite element model of the sun gear.

[0087] In the step of S211b, the sun gear is defined according to the specific heat capacity, density and thermal conductivity of the actual material of the sun gear; the fluid domain close to the sun gear is set as a rotating domain, and the fluid domain far from the sun gear is set as a stationary domain. In the step of S212b, the geometric model of the sun gear is divided into a tetrahedral type grid scheme using Fluent Meshing, and is imported into CFX-Pre. In the step of S213b, the surface heat source of the sun gear and the volume heat source of the sun bearing are added to the surface of the sun gear and the bearing of the sun gear, respectively.

[0088] S220b, boundary conditions are set in the Ansys CFX finite element model of the sun gear and solved to obtain the temperature field of the sun gear. Specifically, the corresponding speed of the sun gear and the initial temperature of the surrounding lubricating oil are set, the Ansys CFX finite element model of the sun gear is input into the CFX Solver for calculation, and the temperature field and velocity field distribution results of the sun gear are obtained.

[0089] S300, calculating the equivalent thermal resistance of the planetary gear according to the temperature field, surface area parameter and heat source of the planetary gear, and calculating the equivalent thermal resistance of the sun gear according to the temperature field, surface area parameter and heat source of the sun gear;

[0090] In step S300, the step of calculating the equivalent thermal resistance of the planetary gear according to the temperature field, surface area parameter and heat source of the planetary gear includes:

[0091] S310a, calculating the convective surface heat transfer coefficient of the planetary gear according to the temperature field, surface area parameter and heat source of the planetary gear;

[0092] S320a, simplifying the structure of the planetary gear;

[0093] S330a, calculating the equivalent thermal resistance of the simplified planetary gear according to the convective surface heat transfer coefficient of the planetary gear.

[0094] In step S300, the step of calculating the equivalent thermal resistance of the sun gear according to the temperature field, surface area parameter and heat source of the sun gear includes:

[0095] S310b, calculating the convective surface heat transfer coefficient of the sun gear according to the temperature field, surface area parameter and heat source of the sun gear;

[0096] S320b, simplifying the structure of the sun gear;

[0097] S330b, calculating the equivalent thermal resistance of the simplified sun gear according to the convective surface heat transfer coefficient of the sun gear.

[0098] In step S310a and step S310b, the calculation formula of the convective surface heat transfer coefficient of the planetary gear is as follows:

[0099]

[0100] In the formula, h is the convective surface heat transfer coefficient, Q is the total power loss of the planetary gear or the sun gear, A is the effective heat transfer area of the outer peripheral surface of the planetary gear or the sun gear, and the wall temperature t w is the average temperature of the gear wall, the temperature t f is the average temperature of the lubricating oil fluid and the channel wall interface;

[0101] Specifically, Q is generally calculated mechanically using the radial force and rotational speed of the gears, combined with theoretical calculation formulas, and is used as a known condition in the calculation formula for the heat transfer coefficient of the convective surface; refer to Figure 2 As shown, the wall temperature t w and temperature t f The temperature field obtained after simulation is used as a known condition in the calculation formula for the heat transfer coefficient of the convective surface.

[0102] In steps S330a and S330b, the formula for calculating the equivalent thermal resistance of the simplified sun gear is as follows:

[0103]

[0104] In the formula, R is the equivalent thermal resistance, h is the convective surface heat transfer coefficient, A is the effective heat transfer area of ​​the outer peripheral surface of the planetary gear or sun gear, and A′ is the outer peripheral surface area of ​​the planetary gear or sun gear after structural simplification.

[0105] Reference Figure 2 As shown, in steps S320a and S320b, the structural simplification of the planetary gear specifically involves simplifying the geometric model of the planetary gear into a cylinder; the structural simplification of the sun gear specifically involves simplifying the geometric model of the sun gear into a cylinder.

[0106] Specifically, through Boolean operations, the planetary gears and sun gears are simplified into cylinders of the same volume. By simplifying the physical model of the planetary gears or sun gears, the meshing of the planetary gears or sun gears is made easier. The physical model of the planetary gears or sun gears is simplified into a symmetrical body, reducing the number of meshes, further reducing the computational load of the 3D model, further improving the computational accuracy, and shortening the computation time.

[0107] S400. Construct a physical model of the reducer based on its actual geometric parameters.

[0108] Specifically, the reducer components are modeled and assembled according to their actual dimensions to obtain a physical model of the reducer, which is then imported into Ansys CFX.

[0109] S500. In Ansys CFX, set the finite element parameters of the reducer, and apply the equivalent thermal resistance of the sun gear and the equivalent thermal resistance of the planetary gear to the sun gear and planetary gear in the physical model of the reducer, respectively, to construct the Ansys CFX finite element model of the reducer.

[0110] Step S500 includes:

[0111] S510, unit selection and material setting are performed on all components in the physical model of the speed reducer in the Ansys CFX finite element model.

[0112] S520, meshing is performed on all components in the physical model of the speed reducer in the Ansys CFX finite element model. The specific steps of S520 are as follows: the geometric model of the speed reducer is divided into a tetrahedral type mesh scheme using Fluent Meshing, and is imported into CFX-Pre.

[0113] S530, the heat load of each heat generating component in the physical model of the speed reducer is set in the Ansys CFX finite element model, and the equivalent thermal resistance of the sun gear and the equivalent thermal resistance of the planetary gear are respectively applied to the surface of the sun gear and the planetary gear in the physical model of the speed reducer to construct the Ansys CFX finite element model of the speed reducer. The specific steps of S530 are as follows: a volume heat source is added to all heat generating components including the planetary gear, the sun gear and the bearing according to the heat load of the speed reducer.

[0114] S600, the temperature and speed distribution field of the speed reducer is obtained according to the Ansys CFX finite element model of the speed reducer.

[0115] Specifically, boundary conditions are set and solved in the Ansys CFX finite element model of the speed reducer to obtain the temperature and speed distribution field of the speed reducer. In the Ansys CFX finite element model of the speed reducer, the internal fluid domain of the gear cavity is defined as a rotating domain model, and the rotating speed is defined. The inlet and outlet boundaries of the speed reducer are set. The Ansys CFX finite element model of the speed reducer is input into the CFX Solver for calculation to obtain the temperature and speed distribution field of the speed reducer, as shown in Figure 3 and Figure 4 .

[0116] In summary, the temperature rise condition obtaining method of the planetary speed reducer provided by the embodiment of the present application: the heat generation and heat transfer mode of the meshing of the planetary gear and the sun gear is characterized by calculating the equivalent thermal resistance, the temperature rise prediction is placed in the design stage of the speed reducer, the prediction accuracy and efficiency of the temperature field and the speed field of the speed reducer are improved, and the design cost and the design cycle of the speed reducer are reduced and shortened. At the same time, the evaluation method avoids using dynamic mesh calculation through the Ansys CFX finite element model simulation method, reduces the calculation amount of the three-dimensional model, further improves the calculation accuracy, and shortens the calculation time.

[0117] In addition to using Ansys CFX to solve and analyze the temperature field and speed field distribution of the planetary reducer, the solving idea proposed by the application can also be realized through an open source platform such as OpenFoam or directly by writing code. This separate simulation of the planetary gear and the sun gear through the equivalent thermal resistance of the planetary gear and the equivalent thermal resistance of the sun gear to represent the solving idea of the heat generation and heat transfer of the meshing of the planetary gear and the sun gear overcomes the shortcomings of the traditional finite element analysis method in considering the gear meshing, such as poor calculation accuracy, large calculation amount, long temperature rise prediction period, and has the technical effects of convenient calculation, accurate calculation, can accurately calculate the temperature field and speed field of the reducer, puts the temperature rise prediction into the reducer design stage, reduces the cost, and can be widely applied to the technical field of the reducer.

[0118] Obviously, the above embodiments are only examples for clearly illustrating but not limiting the embodiments. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. Here, all the embodiments cannot be exhausted, and the obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. A method for obtaining temperature rise condition of a planetary reducer based on a finite element simulation analysis platform, characterized in that, The method comprises the following steps: constructing a physical model of the planetary gear according to actual geometric parameters of the planetary gear and constructing a physical model of the sun gear according to actual geometric parameters of the sun gear; setting finite element parameters of the planetary gear to obtain a temperature field of the planetary gear, including: setting finite element parameters of the planetary gear to construct a finite element model of the planetary gear; setting boundary conditions and solving in the finite element model of the planetary gear to obtain a temperature field of the planetary gear; setting finite element parameters of the sun gear to obtain a temperature field of the sun gear, including: setting finite element parameters of the sun gear to construct a finite element model of the sun gear; setting boundary conditions and solving in the finite element model of the sun gear to obtain a temperature field of the sun gear; calculating equivalent thermal resistance of the planetary gear according to the temperature field of the planetary gear, a surface area parameter and a heat source, and calculating equivalent thermal resistance of the sun gear according to the temperature field of the sun gear, a surface area parameter and a heat source; constructing a physical model of the reducer according to actual geometric parameters of the reducer; setting finite element parameters of the reducer and applying the equivalent thermal resistance of the sun gear and the equivalent thermal resistance of the planetary gear to the sun gear and the planetary gear in the physical model of the reducer respectively to construct a finite element model of the reducer; the step of setting finite element parameters of the planetary gear to construct a finite element model of the planetary gear comprises: selecting units and setting materials of the planetary gear in the finite element model; meshing the planetary gear in the finite element model; setting thermal load of the planetary gear in the finite element model to construct a finite element model of the planetary gear; the step of setting finite element parameters of the sun gear to construct a finite element model of the sun gear comprises: selecting units and setting materials of the sun gear in the finite element model; meshing the sun gear in the finite element model; setting thermal load of the sun gear in the finite element model to construct a finite element model of the sun gear; obtaining temperature and speed distribution fields of the reducer according to the finite element model of the reducer; the selecting units and setting materials of the planetary gear in the finite element model specifically comprises: defining the planetary gear according to specific heat capacity, density and thermal conductivity of actual material of the planetary gear; setting a fluid domain close to the planetary gear as a rotating domain and setting a fluid domain far from the planetary gear as a stationary domain; the selecting units and setting materials of the sun gear in the finite element model specifically comprises: defining the sun gear according to specific heat capacity, density and thermal conductivity of actual material of the sun gear; setting a fluid domain close to the sun gear as a rotating domain and setting a fluid domain far from the sun gear as a stationary domain; the meshing the planetary gear in the finite element model specifically comprises: dividing the geometric model of the planetary gear into a tetrahedron type mesh scheme; the meshing the sun gear in the finite element model specifically comprises: dividing the geometric model of the sun gear into a tetrahedron type mesh scheme; The step of setting the boundary conditions and solving in the finite element model of the planetary gear to obtain the temperature field of the planetary gear specifically includes: setting the corresponding rotating speed of the planetary gear and the initial temperature of the surrounding lubricating oil, and calculating the finite element model of the planetary gear to obtain the temperature field and speed field distribution results of the planetary gear. The step of setting the boundary conditions and solving in the finite element model of the sun gear to obtain the temperature field of the sun gear specifically includes: setting the corresponding rotating speed of the sun gear and the initial temperature of the surrounding lubricating oil, and calculating the finite element model of the sun gear to obtain the temperature field and speed field distribution results of the sun gear.

2. The method of claim 1, wherein The step of calculating the equivalent thermal resistance of the planetary gear according to the temperature field, surface area parameter and heat source of the planetary gear includes: calculating the convective surface heat transfer coefficient of the planetary gear according to the temperature field, surface area parameter and heat source of the planetary gear, and simplifying the structure of the planetary gear, and calculating the equivalent thermal resistance of the simplified planetary gear according to the convective surface heat transfer coefficient of the planetary gear. The step of calculating the equivalent thermal resistance of the sun gear according to the temperature field, surface area parameter and heat source of the sun gear includes: calculating the convective surface heat transfer coefficient of the planetary gear according to the temperature field, surface area parameter and heat source of the sun gear, and simplifying the structure of the sun gear, and calculating the equivalent thermal resistance of the simplified sun gear according to the convective surface heat transfer coefficient of the sun gear.

3. The method of claim 1, wherein The calculation formula of the convective surface heat transfer coefficient of the planetary gear according to the temperature field, surface area parameter and heat source of the planetary gear and the calculation formula of the convective surface heat transfer coefficient of the planetary gear according to the temperature field, surface area parameter and heat source of the sun gear are as follows: The calculation formula of the equivalent thermal resistance of the simplified planetary gear according to the convective surface heat transfer coefficient of the planetary gear and the calculation formula of the equivalent thermal resistance of the simplified sun gear according to the convective surface heat transfer coefficient of the sun gear are as follows:

4. The method of claim 3, wherein The structure simplification of the planetary gear specifically includes: simplifying the geometric model of the planetary gear into a cylinder. where h is the heat transfer coefficient of the convection surface, Q is the total power loss of the planetary gear or sun gear, A is the effective heat transfer area of the outer peripheral surface of the planetary gear or sun gear, t w is the average temperature of the gear wall surface, and temperature t f is the average temperature of the interface of the lubricating oil fluid and the passage wall surface; The structure simplification of the sun gear specifically includes: simplifying the geometric model of the sun gear into a cylinder. In the formula, R is the equivalent thermal resistance, h is the heat transfer coefficient of the convection surface, A is the effective heat transfer area of the outer peripheral surface of the planetary gear or the sun gear, A ′ is the outer peripheral surface area of the planetary gear or the sun gear after structural simplification.

5. The method of claim 4, wherein, The step of setting the finite element parameters of the reducer, and applying the equivalent thermal resistance of the sun gear and the equivalent thermal resistance of the planetary gear to the sun gear and the planetary gear in the physical model of the reducer respectively to construct the finite element model of the reducer includes: performing unit selection and material setting on all components in the physical model of the reducer in the finite element model; 6. The method of claim 1, wherein performing meshing on all components in the physical model of the reducer in the finite element model; performing meshing on all components in the physical model of the reducer in the finite element model; ​ The thermal load of each heat-generating component in the physical model of the reducer is set in the finite element model, and the equivalent thermal resistance of the sun gear and the equivalent thermal resistance of the planetary gear are respectively applied to the surface of the sun gear and the planetary gear in the physical model of the reducer to construct the finite element model of the reducer.

7. The method of claim 6, wherein the temperature rise of the planetary reducer is obtained by, The unit selection and material setting of all components in the physical model of the reducer in the finite element model are specifically: defining each component according to the specific heat capacity, density and thermal conductivity of all components in the physical model of the reducer, and setting the internal fluid domain of the reducer as a rotating domain; The meshing of all components in the physical model of the reducer in the finite element model is specifically: dividing the geometric model of the reducer into a tetrahedral type mesh scheme; The thermal load of each heat-generating component in the physical model of the reducer in the finite element model is specifically: adding a body heat source to all heat-generating components including the planetary gear, the sun gear and the bearing according to the thermal load of the reducer.

8. The method of claim 6, wherein the temperature rise of the planetary reducer is obtained by, The step of obtaining the temperature and speed distribution field of the reducer according to the finite element model of the reducer includes: setting and solving the boundary conditions in the finite element model of the reducer to obtain the temperature and speed distribution field of the reducer.

9. The method of claim 8, wherein, In the finite element model of the reducer, the internal fluid domain of the gear cavity is defined as a rotating domain model, and the rotating speed is defined; the inlet and outlet boundaries of the reducer are set; the finite element model of the reducer is calculated to obtain the temperature and speed distribution field of the reducer.

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