CN114547909A - Wet friction pair temperature field determination method and system - Google Patents
Wet friction pair temperature field determination method and system Download PDFInfo
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Abstract
The invention relates to a method and a system for determining a temperature field of a wet friction pair, which relate to the field of wet clutches, wherein the method comprises the steps of obtaining parameters of dual steel sheets, parameters of friction plates and parameters of grooves of the wet clutches; equivalently simplifying the groove parameters to obtain radial fan-shaped groove parameters; constructing a two-dimensional section model according to the friction plate parameters, the dual steel sheet parameters and the radial fan-shaped groove parameters; carrying out mesh division and boundary heat transfer state analysis on the two-dimensional section model, and determining an initial condition and a boundary condition; constructing a temperature field model by using heat conduction according to the initial condition and the boundary condition; and determining the temperature field distribution of the wet friction pair according to the temperature field model. The invention can improve the measurement precision of the wet friction pair temperature field.
Description
Technical Field
The invention relates to the field of wet clutches, in particular to a wet friction pair temperature field determining method and system.
Background
The wet clutch is a clutch cooled by oil, is an important component of a vehicle transmission system, and the friction temperature rise state of a friction element of the wet clutch has great influence on the performance of a vehicle. Wet clutches have the advantages of high transmissible torque and long service life, and are therefore widely used in heavy vehicles. The friction plate is easy to be accumulated to fail or is easy to be worn and damaged by abnormal friction under the condition of long-time work or limit working condition, and even can be deformed and burnt. The wet clutch makes the important index of vehicle performance directly influence whether the vehicle is started or shifted stably, and the temperature rise characteristic of friction plate friction is influenced by a plurality of elements, such as rotating speed difference, operating oil pressure, lubricating condition and action time, so that the research on the friction plate friction temperature rise characteristic becomes very complicated. The failure of the friction plate of the wet clutch has great influence on the performance of a vehicle, and the failure of the friction plate is closely related to the temperature rise characteristic of sliding friction, so that a method for solving the temperature field of the wet friction pair is an urgent matter.
In recent years, the sliding friction temperature rise characteristic of the wet clutch is gradually emphasized at home and abroad, and related researches are gradually increased. A sliding friction temperature field prediction model based on a simulated extreme working condition is established in the construction aspect of the prediction model; the students analyze the transient heat conduction of the transient friction interface and carry out a large amount of researches on the heat load characteristics of the friction plate; some scholars study the combination process of the clutch from different angles and study the temperature field of different material parameters; the students also apply various engineering technical means such as an optical fiber sensor, a thermal infrared imager and the like to research the temperature field distribution under the constant-speed sliding working condition; in the aspect of deformation and instability research, the conclusion is drawn through comparison of numerical simulation and test: radial temperature variation is the main cause of buckling deformation.
In the previous research, the friction coefficient is mostly a fixed empirical value, the state of a friction interface is mostly the case of single heat flow input, uneven contact and double-arc groove heat dissipation of the clutch are not fully considered, and the result has certain deviation from the actual value.
Disclosure of Invention
The invention aims to provide a method and a system for determining a wet friction pair temperature field so as to improve the measurement accuracy of the wet clutch friction pair temperature field.
In order to achieve the purpose, the invention provides the following scheme:
a wet friction pair temperature field determination method, comprising:
acquiring parameters of dual steel sheets, friction plates and grooves of a wet clutch;
equivalently simplifying the groove parameters to obtain radial fan-shaped groove parameters;
constructing a two-dimensional section model according to the friction plate parameters, the dual steel sheet parameters and the radial fan-shaped groove parameters;
carrying out mesh division and boundary heat transfer state analysis on the two-dimensional section model, and determining an initial condition and a boundary condition;
constructing a temperature field model by using heat conduction according to the initial condition and the boundary condition;
and determining the temperature field distribution of the wet friction pair according to the temperature field model.
Optionally, the equivalently simplifying the groove parameters to obtain radial fan-shaped groove parameters specifically includes:
and simplifying the groove parameters in an equal area or equal volume manner to obtain radial fan-shaped groove parameters.
Optionally, the grid division and boundary heat transfer state analysis on the two-dimensional cross-section model to determine an initial condition and a boundary condition specifically includes:
determining the input heat flow of a contact surface according to the parameters of the dual steel sheets and the parameters of the friction plates in the two-dimensional section model;
determining the convective heat transfer coefficient of the rectangular surface of the steel sheet corresponding to the groove according to the parameters of the friction plate in the two-dimensional section model;
determining the convective heat transfer coefficient of an oil film area according to the friction plate oil in the two-dimensional section model;
determining equivalent convective heat transfer coefficients between pairs according to the convective heat transfer coefficients of the rectangular steel sheet surfaces corresponding to the grooves and the convective heat transfer coefficients of the oil film areas;
and determining initial conditions and boundary conditions according to the input heat flow of the contact surface and the equivalent convective heat transfer coefficient between the pairs.
Optionally, the determining the input heat flow of the contact surface according to the parameters of the dual steel sheets and the parameters of the friction plates in the two-dimensional section model specifically includes:
and multiplying the steel sheet heat flow distribution coefficient, the friction coefficient, the uniformly distributed pressure of the steel sheet at the set end, the relative angular velocity and the radial radius of the steel sheet to obtain the input heat flow of the contact surface.
Optionally, the expression of the steel sheet heat flow distribution coefficient is as follows:
wherein gamma is the heat flow distribution coefficient of the steel sheet, ksFor dual sheet thermal conductivity, ρsDensity of dual steel sheet, csSpecific heat of coupled steel sheet, kfIs the thermal conductivity of the friction plate, rhofIs the friction disc density, cfIs the specific heat of the friction plate.
Optionally, an expression of the convective heat transfer coefficient of the rectangular surface of the steel sheet corresponding to the groove is as follows:
wherein h iscThe heat convection coefficient of the rectangular surface of the steel sheet corresponding to the groove is shown, lambda is the heat conductivity coefficient of oil, Re2Is Reynolds number, Pr is the Plantt coefficient, l2Is the characteristic length of oil in the oil groove.
Optionally, the expression of the convective heat transfer coefficient of the oil film region is as follows:
wherein h isrIs the convective heat transfer coefficient of the oil film area, lambda is the heat conductivity coefficient of the oil, r is the radial radius of the steel sheet, Nu1Is the Nussel number，m2Is a radial temperature distribution index, Re1Reynolds number, Pr is the Plantt coefficient.
Optionally, the constructing a temperature field model by using heat conduction according to the initial condition and the boundary condition specifically includes:
discretizing the initial condition and the boundary condition to obtain an internal node explicit differential format equation;
and processing the internal node explicit difference format equation by utilizing a Fourier rule to obtain a temperature field model.
Optionally, the expression of the temperature field model is:
wherein, the first and the second end of the pipe are connected with each other,
temperature with coordinates (i, j) at time k, FoIn order to set the coefficients for the purpose of,
is the temperature of the coordinate (i, j) at time k-1,
is the temperature of the coordinate (i +1, j) at the time k-1,
is the temperature of the coordinate (i-1, j) at the time k-1,
is the temperature of the coordinate (i, j +1) at the time k-1,
is the temperature at time k-1, coordinate (i, j-1), i is the abscissa, j is the ordinate, and k is time k.
A wet friction pair temperature field determining system comprising:
the acquisition module is used for acquiring parameters of dual steel sheets, parameters of friction plates and parameters of grooves of the wet clutch;
the equivalent simplification module is used for carrying out equivalent simplification on the groove parameters to obtain radial fan-shaped groove parameters;
the first construction module is used for constructing a two-dimensional section model according to the friction plate parameters, the dual steel sheet parameters and the radial fan-shaped groove parameters;
the grid division and boundary heat transfer state analysis module is used for carrying out grid division and boundary heat transfer state analysis on the two-dimensional section model and determining initial conditions and boundary conditions;
a second construction module for constructing a temperature field model using thermal conduction according to the initial condition and the boundary condition;
and the wet friction pair temperature field distribution determining module is used for determining the wet friction pair temperature field distribution according to the temperature field model.
According to the specific embodiment provided by the invention, the invention discloses the following technical effects:
the method equivalently simplifies the groove parameters to obtain radial fan-shaped groove parameters; constructing a two-dimensional section model according to the friction plate parameters, the dual steel sheet parameters and the radial fan-shaped groove parameters; carrying out grid division and boundary heat transfer state analysis on the two-dimensional section model, and determining an initial condition and a boundary condition; constructing a temperature field model by utilizing heat conduction according to the initial condition and the boundary condition; and determining the temperature field distribution of the wet friction pair according to the temperature field model. In the process of establishing the temperature field model, the groove cooling effect is considered, and the equal volume of the groove is simplified, so that the accuracy of temperature field distribution measurement is improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.
FIG. 1 is a flow chart of a method for determining a temperature field of a wet friction pair according to the present invention;
FIG. 2 is a detailed flowchart of a method for determining a temperature field of a wet friction pair according to the present invention in practical application;
FIG. 3 is an equivalent simplified diagram of a trench;
FIG. 4 is a schematic diagram of dual steel sheet meshing and heat conduction;
FIG. 5 is a temperature field profile of a steel sheet wiping contact surface.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
As shown in fig. 1, the method for determining a temperature field of a wet friction pair according to the present invention includes:
step 101: and acquiring parameters of dual steel sheets, friction plates and grooves of the wet clutch.
Step 102: and equivalently simplifying the groove parameters to obtain radial fan-shaped groove parameters. Step 102, specifically comprising: and simplifying the groove parameters in an equal area or equal volume manner to obtain radial fan-shaped groove parameters.
Step 103: and constructing a two-dimensional section model according to the friction plate parameters, the dual steel sheet parameters and the radial fan-shaped groove parameters.
Step 104: and carrying out grid division and boundary heat transfer state analysis on the two-dimensional section model, and determining initial conditions and boundary conditions.
Step 105: and constructing a temperature field model by utilizing heat conduction according to the initial condition and the boundary condition. Step 105, specifically comprising:
discretizing the initial condition and the boundary condition to obtain an internal node explicit differential format equation; and processing the internal node explicit difference format equation by utilizing a Fourier criterion to obtain a temperature field model.
Wherein the expression of the temperature field model is as follows:
wherein the content of the first and second substances,
temperature with coordinates (i, j) at time k, FoTo set the coefficients, wherein the set coefficients are the sorted coefficients,
a is the thermal diffusivity of the material, tau is the time step length, h is the space step length,
is the temperature of the coordinate (i, j) at time k-1,
is the temperature of the coordinate (i +1, j) at the time k-1,
is the temperature of the coordinate (i-1, j) at time k-1,
is the temperature of the coordinate (i, j +1) at the time k-1,
is the temperature at time k-1, coordinate (i, j-1), i is the abscissa, j is the ordinate, and k is time k.
Step 106: and determining the temperature field distribution of the wet friction pair according to the temperature field model.
and determining the input heat flow of the contact surface according to the parameters of the dual steel sheets and the parameters of the friction plates in the two-dimensional section model. The method for determining the input heat flow of the contact surface according to the parameters of the dual steel sheets and the parameters of the friction plates in the two-dimensional section model specifically comprises the following steps: and multiplying the steel sheet heat flow distribution coefficient, the friction coefficient, the uniformly distributed pressure of the steel sheet at the set end, the relative angular velocity and the radial radius of the steel sheet to obtain the input heat flow of the contact surface. The expression of the steel sheet heat flow distribution coefficient is as follows:
wherein gamma is the heat flow distribution coefficient of the steel sheet, ksFor dual sheet thermal conductivity, ρsDensity of dual steel sheet, csSpecific heat of coupled steel sheet, kfIs the thermal conductivity of the friction plate, rhofIs the density of the friction disk, cfThe specific heat of the friction plate.
And determining the convective heat transfer coefficient of the rectangular surface of the steel sheet corresponding to the groove according to the parameters of the friction plate in the two-dimensional section model. The expression of the convective heat transfer coefficient of the rectangular surface of the steel sheet corresponding to the groove is as follows:
wherein h iscThe heat convection coefficient of the rectangular surface of the steel sheet corresponding to the groove is represented by lambda, the heat conductivity coefficient of the oil is represented by Re2Is Reynolds number, Pr is the Plantt coefficient, l2Is the characteristic length of oil in the oil groove.
And determining the convective heat transfer coefficient of an oil film area according to the friction plate oil in the two-dimensional section model. The expression of the convective heat transfer coefficient of the oil film area is as follows:
wherein h isrIs the convective heat transfer coefficient of the oil film area, lambda is the heat conductivity coefficient of the oil, r is the radial radius of the steel sheet, Nu1Is the Nussel number, m2Is the radial distribution index of temperature, Re1Reynolds number, Pr is the Plantt coefficient.
And determining the equivalent convective heat transfer coefficient between the pairs according to the convective heat transfer coefficient of the rectangular surface of the steel sheet corresponding to the groove and the convective heat transfer coefficient of the oil film area.
And determining initial conditions and boundary conditions according to the input heat flow of the contact surface and the equivalent convective heat transfer coefficient between the pairs.
The invention provides a wet friction pair temperature field determining system, which comprises:
and the acquisition module is used for acquiring parameters of dual steel sheets, parameters of friction plates and parameters of grooves of the wet clutch.
And the equivalent simplification module is used for carrying out equivalent simplification on the groove parameters to obtain radial fan-shaped groove parameters.
And the first construction module is used for constructing a two-dimensional section model according to the friction plate parameters, the dual steel sheet parameters and the radial fan-shaped groove parameters.
And the grid division and boundary heat transfer state analysis module is used for carrying out grid division and boundary heat transfer state analysis on the two-dimensional section model and determining initial conditions and boundary conditions.
A second construction module for constructing a temperature field model using thermal conduction based on the initial conditions and the boundary conditions.
And the wet friction pair temperature field distribution determining module is used for determining the wet friction pair temperature field distribution according to the temperature field model.
According to the method, the groove cooling effect, the local heat dissipation of the contact surface and the real-time change of the friction coefficient are considered, the two-dimensional temperature field numerical model is established and solved, the equivalent convection heat transfer coefficient and the equivalent gain coefficient between the pairs are introduced, and compared with the original model, the calculation result of the optimization model is more accurate.
In the process of establishing a two-dimensional temperature field numerical model, firstly, the structure of the groove of the clutch friction plate is considered to be complex, and certain deviation is caused to the result by directly omitting the structure, so that as shown in fig. 3, the groove is simplified by adopting an equal volume method, and the groove (such as a double-arc groove, a concentric groove, a square groove and the like) is equivalent to a simple radial fan-shaped groove. Selecting the section of the friction plate to establish a two-dimensional heat conduction equation of a rectangular coordinate system, performing two-dimensional grid division, assuming that the temperature field of the friction element is symmetrical about a midplane, taking half of the section for research, and performing no heat exchange on the midplane about the y direction, so that the boundary condition of the midplane is thermal insulation; when the boundary heat transfer state of the upper plane is analyzed, because of the existence of the grooves, the contact state of the upper plane is not constant all the time, but is alternately performed under the two conditions of contact with oil and contact with the friction plate, so that the boundary condition of the upper plane is defined as that heat flow input and convection heat exchange are alternately performed; for both sides of the cross section, the inner diameter and the outer diameter of the friction plate are correspondingly contacted with oil liquid, so that the inner diameter convective heat transfer and the outer diameter convective heat transfer are set respectively. After the heat transfer state of the boundary is analyzed, discretizing the initial condition and the boundary condition, sorting the internal nodes based on Fourier criterion and sorting the parameters in the calculation formula. Wherein, in order to make the model more similar to the actual situation, the heat dissipation capacity of the local oil film of the contact surface is equivalent to the calculation of the alternate boundary condition of the convection heat exchange part of the groove, and the equivalent convection heat exchange coefficient h between the pairs is introducedbAnd an equivalent gain factor a. And programming the formula, and substituting the formula into the set parameter value to obtain the temperature field distribution diagram. The method mainly comprises four steps:
the first step of model establishment is to select an object to be researched, because the temperature field distribution of the wet friction pair is assumed to be consistent along the circumferential direction, the temperature in the radial direction is mainly researched, the selected object is the cross section of the annular friction plate, and the cross section is a regular rectangle, so that subsequent grid division is facilitated.
The second step of discretization is a solving method, namely, the two-dimensional section model is firstly subjected to grid division, then the temperature of the grid at the next moment is calculated by using the temperatures of a plurality of grids around the grid at the previous moment, and the situation that no grid exists in one direction around the boundary can occur at the moment, so that the boundary condition needs to be defined, and in addition, the initial condition is the temperature at the moment when t is 0.
The third step is to solve the heat flow input, which is actually the value of q needed in the calculation of the second step, and a series of formulas are needed to solve the problem.
The fourth step is to solve the coefficients, and some coefficients are uncertain in the second step and need to be calculated. After the parameters used in the second step are all solved, the model is solved.
As shown in fig. 2, the present invention further provides a specific implementation process of the wet friction pair temperature field determination method, as follows:
step 1: establishing a two-dimensional section model
The first step of establishing the model aims to select the research object of the invention, which is to solve the temperature field of the whole annular friction plate, and the section of the research object is selected as the research object.
1. Model building
It is known that both friction plate and dual steel plate are regular ring shape, and the temperature field of friction element is assumed to be symmetrical about the middle plane, i.e. the middle plane is considered as heat insulation plane, and the properties of friction material (except friction coefficient) do not change with temperature and direction. The steel sheet near the piston end is uniformly distributed with pressure p, the temperature field distribution of the wet friction pair is basically consistent along the circumferential direction, and then the radial section of the steel sheet is taken as a modeling research object, namely the view angle of figure 3, and the two-dimensional heat conduction equation of a rectangular coordinate system is established as follows:
wherein, T is temperature value, a is k/rho c is material thermal diffusivity; k. ρ and c are the thermal conductivity, density and specific heat of the material, respectively. In order to set boundary conditions conveniently, the double-arc grooves on the surface of the friction plate are simplified into radial fan-shaped grooves with equal areas and equal volumes. The two-dimensional conduction equation is what the spatial distribution of the temperature field is over time, and is intended to account for the temperature field across the cross-section given the boundary conditions and initial conditions.
Step 2: the first step is to select and establish a model, the subsequent work is to solve the temperature change by a discretization method, grid division is a calculation means, initial values and boundary conditions are set for the subsequent calculation, the boundary conditions are set by combining with the actual situation analysis, the temperature of each position can be solved by combining the initial values and the boundary conditions, and then the temperature of each position at different times is calculated by a formula (4).
2. Establishment and discretization of boundary conditions and initial conditions
As shown in fig. 4, a radial two-dimensional cross-sectional mathematical model of the friction plate is subjected to meshing and boundary heat transfer state analysis, as shown in fig. 4. The boundary conditions and initial conditions may be expressed as:
in the formula, T∞Is the ambient temperature of the oil, ksIs the sheet thermal conductivity, hi、hoThe convection heat transfer coefficients of the inner and outer diameters of the steel sheet hbThe equivalent convection heat transfer coefficient between the pairs is shown, and q is the input heat flow of the contact surface. T (x, y) is the temperature with coordinates (x, y),
for the input of the heat flow,
for convective heat transfer, gamma4For mid-plane thermal insulation, gamma2For internal-diameter convective heat transfer, gamma3For the outer diameter convective heat transfer, s is the leftmost abscissa, and d is the uppermost ordinate.
Further discretizing the expression (2), wherein the internal nodes adopt an explicit difference format as follows:
in the formula, τ is a time step, h is a space step, and i and j respectively represent coordinate nodes in x and y directions. Based on Fourier criterion, the following steps are obtained:
equation (4) represents a temperature field model, which is a relationship between the temperature T at the time k and the temperature T at the time k-1.
And step 3: the formula obtained in the second step is a calculation flow and means, unknown parameters are obtained for calculation, the parameter heat flow q is calculated in the second step, and then the calculation of q in the second step involves the calculation of the parameters gamma and mu (V, T', p).
3. Calculating input heat flow
q＝γ·μ(V,T',p)·p·ω·r (6)
Wherein gamma is the heat flow distribution coefficient of the steel sheet, omega is the relative angular velocity, and r is the radial radius of the steel sheet. The heat conductivity coefficients of the powder metallurgy material of the friction plate and the 65Mn material of the steel sheet are greatly different, and the heat flow distribution coefficient gamma of the steel sheet is as follows:
in the formula, the corner marks s and f represent dual rigid plates and friction plates. The friction coefficient in the general modeling uses a fixed empirical value, changes along with temperature, rotating speed and pressure in the actual working condition, and is corrected into the following value based on a large amount of bench test data according to a friction coefficient fitting formula:
wherein V is the sliding friction linear velocity and T' is the contact node Kelvin temperature.
And 4, step 4: based on the second step, calculating parameters in the formula of the second step, and the heat convection coefficient h under different conditions, wherein in the calculation process, in order to obtain a result with smaller error with the actual condition, the equivalent heat convection coefficient h between pairs is introducedbAnd an equivalent gain factor a.
4. Calculation of convective Heat transfer coefficient
In the normal operation of the wet clutch, the heat dissipation of the steel sheet is roughly divided into three parts: the inner and outer diameter surfaces exchange heat with oil and air in a convection way; the convection heat exchange between the oil-gas mixture in the groove and the steel sheet is carried out; the contact surface is locally oil film convective heat transfer as shown in fig. 2. Firstly, the convection heat transfer of the inner and outer diameter surfaces of the friction pair can be regarded as the convection heat transfer of the oil transversely swept cylinder:
in the formula, h(i,o)Is the convective heat transfer coefficient of the oil transverse cylinder, lambda is the oil heat conductivity coefficient, v(i，o)Is the inner and outer ring linear velocity, d(i，o)The diameters of the inner and outer ring surfaces, Pr is the Plantt coefficient, z is the kinematic viscosity of the oil, rholIs the oil density, clThe specific heat of oil liquid and the empirical coefficient m1And n is 0.193 and 0.618 respectively. The convective heat transfer coefficient h of the inner and outer diameter surfaces of the friction pair is obtained by the formula (9)(i)And h(0)And is thus substituted into equation (2). Consider to connectThe contact surface local oil film convection heat transfer has the following expression of the convection heat transfer coefficient of an oil film area:
Nu1＝0.664Re1 1/2Pr1/3 (13)
in the formula: re is Reynolds number (laminar state because Re is much less than 2X 105), u is liquid flow rate, Nu is Nussel number, l is1Is the characteristic length of the oil in local contact, g is the gravity coefficient, m2Taking m as radial distribution index of temperature22. Considering the convective heat transfer of oil, air and steel sheet in the groove, the convective heat transfer coefficient of the steel sheet rectangular surface corresponding to the groove is:
l2＝ro-re (15)
in the formula I2Is the characteristic length r of oil in the oil grooveoIs the length of the outer radius, reIs the inner radius length. The heat dissipation capacity of the local oil film of the contact surface is equivalent to the calculation of the alternate boundary condition of the convection heat exchange part of the groove, and the equivalent convection heat exchange coefficient h between pairs is definedbAnd equivalent gain factor a:
hb＝hc+A·hr (16)
in the formula, SaArea of the groove region of the friction plate, SbThe area of the oil film bearing area of the friction plate.
5. At this point, the whole model is built, the model is programmed, and the temperature field can be obtained by inputting corresponding parameters, and the final presentation result of the invention is the temperature field distribution diagram shown in fig. 5.
In the process of establishing the two-dimensional temperature field model, the groove cooling effect is considered, the equal volume simplification of the groove is carried out, and when the boundary condition is defined, a method of alternating heat flow input and convection heat exchange is introduced into the upper plane, so that the mathematical model is more consistent with the actual condition, and the accuracy of the model is improved. The method considers the real-time change of the local heat dissipation and the friction coefficient of the contact surface, and enables the heat dissipation capacity of the local oil film of the contact surface to be equivalent to the calculation of the alternate boundary condition of the convection heat exchange part of the groove, so that the finally obtained model is more accurate, and the temperature deviation from the actual temperature is smaller.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. For the system disclosed by the embodiment, the description is relatively simple because the system corresponds to the method disclosed by the embodiment, and the relevant points can be referred to the method part for description.
The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the foregoing, the description is not to be taken in a limiting sense.
Claims (10)
1. A wet friction pair temperature field determination method is characterized by comprising the following steps:
acquiring parameters of dual steel sheets, friction plates and grooves of a wet clutch;
equivalently simplifying the groove parameters to obtain radial fan-shaped groove parameters;
constructing a two-dimensional section model according to the friction plate parameters, the dual steel sheet parameters and the radial fan-shaped groove parameters;
performing grid division and boundary heat transfer state analysis on the two-dimensional section model, and determining initial conditions and boundary conditions;
constructing a temperature field model by using heat conduction according to the initial condition and the boundary condition;
and determining the temperature field distribution of the wet friction pair according to the temperature field model.
2. The method for determining the temperature field of a wet friction pair according to claim 1, wherein the equivalently simplifying the groove parameters to obtain radial fan-shaped groove parameters specifically comprises:
and simplifying the groove parameters in an equal area or equal volume manner to obtain radial fan-shaped groove parameters.
3. The method for determining the temperature field of the wet friction pair according to claim 1, wherein the step of performing meshing and boundary heat transfer state analysis on the two-dimensional cross-sectional model to determine initial conditions and boundary conditions specifically comprises:
determining the input heat flow of a contact surface according to the parameters of the dual steel sheets and the parameters of the friction plates in the two-dimensional section model;
determining the convective heat transfer coefficient of the rectangular surface of the steel sheet corresponding to the groove according to the parameters of the friction plate in the two-dimensional section model;
determining the convective heat transfer coefficient of an oil film area according to the friction plate oil in the two-dimensional section model;
determining equivalent convective heat transfer coefficients between pairs according to the convective heat transfer coefficients of the rectangular steel sheet surfaces corresponding to the grooves and the convective heat transfer coefficients of the oil film areas;
and determining initial conditions and boundary conditions according to the input heat flow of the contact surface and the equivalent convective heat transfer coefficient between the pairs.
4. The method for determining the temperature field of the wet friction pair according to claim 3, wherein the determining the contact surface input heat flow according to the parameters of the pair of steel sheets and the parameters of the friction sheet in the two-dimensional cross-sectional model specifically comprises:
and multiplying the steel sheet heat flow distribution coefficient, the friction coefficient, the uniformly distributed pressure of the steel sheet at the set end, the relative angular velocity and the radial radius of the steel sheet to obtain the input heat flow of the contact surface.
5. The method for determining the temperature field of a wet friction pair as claimed in claim 4, wherein the steel sheet heat flow distribution coefficient is expressed by:
wherein gamma is the heat flow distribution coefficient of the steel sheet, ksFor dual sheet thermal conductivity, ρsDensity of dual steel sheet, csSpecific heat of coupled steel sheet, kfIs the thermal conductivity of the friction plate, rhofIs the density of the friction disk, cfIs the specific heat of the friction plate.
6. The method for determining the temperature field of the wet friction pair according to claim 3, wherein the expression of the convective heat transfer coefficient of the rectangular surface of the steel sheet corresponding to the groove is as follows:
wherein h iscThe heat convection coefficient of the rectangular surface of the steel sheet corresponding to the groove is represented by lambda, the heat conductivity coefficient of the oil is represented by Re2Is Reynolds number, Pr is the Plantt coefficient, l2Is the characteristic length of the oil in the oil groove.
7. The wet friction pair temperature field determining method according to claim 3, wherein the expression of the convective heat transfer coefficient of the oil film region is:
wherein h isrIs the convective heat transfer coefficient of the oil film area, lambda is the heat conductivity coefficient of the oil, r is the radial radius of the steel sheet, Nu1Is the Nussel number, m2Is a radial temperature distribution index, Re1Reynolds number, Pr is the Plantt coefficient.
8. The method for determining the temperature field of a wet friction pair according to claim 1, wherein the constructing a temperature field model using heat conduction according to the initial condition and the boundary condition specifically comprises:
discretizing the initial condition and the boundary condition to obtain an internal node explicit differential format equation;
and processing the internal node explicit difference format equation by utilizing a Fourier rule to obtain a temperature field model.
9. The wet friction pair temperature field determining method according to claim 1, wherein the expression of the temperature field model is:
wherein the content of the first and second substances,
temperature with coordinates (i, j) at time k, FoIn order to set the coefficients for the purpose of,
is the temperature of the coordinate (i, j) at time k-1,
is the temperature of the coordinate (i +1, j) at the time k-1,
as a time coordinate of k-1(ii) the temperature of (i-1, j),
is the temperature of the coordinate (i, j +1) at the time k-1,
is the temperature at time k-1, coordinate (i, j-1), i is the abscissa, j is the ordinate, and k is time k.
10. A wet friction pair temperature field determining system, comprising:
the acquisition module is used for acquiring parameters of dual steel sheets, parameters of friction plates and parameters of grooves of the wet clutch;
the equivalent simplification module is used for carrying out equivalent simplification on the groove parameters to obtain radial fan-shaped groove parameters;
the first construction module is used for constructing a two-dimensional section model according to the friction plate parameters, the dual steel sheet parameters and the radial fan-shaped groove parameters;
the mesh division and boundary heat transfer state analysis module is used for carrying out mesh division and boundary heat transfer state analysis on the two-dimensional section model and determining initial conditions and boundary conditions;
a second construction module for constructing a temperature field model using thermal conduction according to the initial condition and the boundary condition;
and the wet friction pair temperature field distribution determining module is used for determining the wet friction pair temperature field distribution according to the temperature field model.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115859844A (en) * | 2022-07-29 | 2023-03-28 | 江苏新能源汽车研究院有限公司 | Wet clutch lubrication cooling simulation method |
| CN116776608A (en) * | 2023-06-25 | 2023-09-19 | 西安电子科技大学 | High-precision equivalent rapid analysis method for heat dissipation cold plate |
| CN117725686A (en) * | 2024-02-06 | 2024-03-19 | 北京航空航天大学 | Method for constructing wet-type multi-plate clutch assembly temperature field prediction model |
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115859844A (en) * | 2022-07-29 | 2023-03-28 | 江苏新能源汽车研究院有限公司 | Wet clutch lubrication cooling simulation method |
| CN115859844B (en) * | 2022-07-29 | 2023-10-13 | 江苏新能源汽车研究院有限公司 | Lubrication and cooling simulation method for wet clutch |
| CN116776608A (en) * | 2023-06-25 | 2023-09-19 | 西安电子科技大学 | High-precision equivalent rapid analysis method for heat dissipation cold plate |
| CN116776608B (en) * | 2023-06-25 | 2024-02-06 | 西安电子科技大学 | High-precision equivalent rapid analysis method for heat dissipation cold plate |
| CN117725686A (en) * | 2024-02-06 | 2024-03-19 | 北京航空航天大学 | Method for constructing wet-type multi-plate clutch assembly temperature field prediction model |
| CN117725686B (en) * | 2024-02-06 | 2024-04-12 | 北京航空航天大学 | Method for constructing wet-type multi-plate clutch assembly temperature field prediction model |
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