A clutch intermittent contact equivalent temperature field calculation method and device

Abstract

The application discloses a kind of clutch intermittent contact equivalent temperature field calculation method and device, comprising: obtaining the friction element that has occurred warping deformation, and the static test is carried out to friction element, obtains the actual contact area of friction element;The coordinate feature of the actual contact area of friction element is obtained, and the contact area of actual contact area is calculated according to coordinate feature, and the shape feature of actual contact area is estimated;The contact pressure of actual contact area is calculated according to the contact area of actual contact area, and the heat flux density distribution of calculation area is obtained according to contact pressure;The thermal boundary condition of contact area is determined, and the temperature field feature of actual contact area is calculated based on the heat flux density distribution of calculation area.The precision and accuracy of clutch temperature field calculation are improved, which provides theoretical basis for failure monitoring and evaluation of friction element, and has important reference significance for clutch safety design, combination control, life evaluation.

Description

Technical Field

[0001] This invention belongs to the field of automotive clutch technology, and particularly relates to a method and apparatus for calculating the equivalent temperature field of intermittent clutch contact. Background Technology

[0002] Wet shift clutches are widely used in vehicle transmissions due to their unique advantages such as high load-bearing capacity, large torque transmission, and simple structure, and are a core component of various stepped transmission systems. During wet clutch engagement, the contact friction between the friction elements generates a large amount of frictional heat, leading to a sudden increase in the temperature of the friction elements. However, excessively high friction element temperatures can accelerate wear and even cause failure, affecting the reliability of the transmission and driving safety.

[0003] However, scholars have only studied the temperature field characteristics of intact friction plates. Patent CN202310335032.6 can determine the surface temperature of a wet clutch relatively accurately based on the initial surface temperature at the start, as well as the temperature rise and fall. Patent CN202310332141.2 predicts the final temperature of the clutch based on the original temperature value, temperature correction coefficient, and predicted temperature rise. Patent CN202410376193.4 proposes a temperature field prediction method based on a contact pressure function. However, these patents all assume that the friction elements are in uniform contact and ignore the temperature field characteristics after the friction elements warp and deform.

[0004] Patent ZL202110576122.5 proposes a method and device for obtaining the clutch temperature field based on a non-uniform pressure model, but it only considers the radial contact non-uniformity of the friction elements. Papers such as "Study on the Circumferential Intermittent Contact Temperature Field of Shift Clutch Friction Elements" and "Study on the Contact and Temperature Field Distribution Characteristics of Saddle-Shaped Buckling Deformation of Liquid-Viscous Friction Pairs" both assume an ideal intermittent contact form for the friction elements before calculating the temperature field. To reveal the failure evolution process of the friction elements and accurately trace their failure sources, it is necessary to provide the actual contact characteristics after coarse failure deformation. Based on this, the actual temperature field characteristics and their effects can be calculated. Only then can the clutch failure state be monitored and evaluated in a timely manner during actual vehicle operation, and targeted maintenance measures can be proposed accordingly. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a method and apparatus for calculating the equivalent temperature field of intermittent clutch contact. Specifically, the method for calculating the equivalent temperature field of intermittent clutch contact includes:

[0006] Obtain a friction element that has already warped and deformed, and perform a static pressure test on the friction element to obtain the actual contact area of ​​the friction element;

[0007] Obtain the coordinate features of the actual contact area of ​​the friction element, calculate the contact area of ​​the actual contact area based on the coordinate features, and estimate the shape features of the actual contact area.

[0008] The contact pressure of the actual contact area is calculated based on the contact area of ​​the actual contact area, and the heat flux density distribution of the calculated area is obtained based on the contact pressure.

[0009] The thermal boundary conditions of the contact area are determined, and the temperature field characteristics of the actual contact area are calculated based on the heat flux density distribution of the calculated area.

[0010] Preferably, the process of performing a static pressure test on the friction element to obtain the actual contact area of ​​the friction element includes:

[0011] The pressure-sensitive test paper, deformable friction element, and complete friction element are stacked in the following order: complete friction element A, pressure-sensitive test paper I, deformable friction element B, pressure-sensitive test paper II, and complete friction element C are stacked in sequence to obtain a friction element combination;

[0012] The friction element assembly is placed on the shelf of the press, and a pressure signal is transmitted to the press through the controller to apply pressure to the friction element assembly; wherein, the pressure applied by the press is the oil pressure value of the clutch under actual vehicle conditions;

[0013] After holding the pressure in the press for a preset time, the pressure is released, and the pressure-sensitive test paper I and pressure-sensitive test paper II are removed. The pressure-sensitive test paper I and pressure-sensitive test paper II are scanned using FPD-8010E analysis software to reveal the actual contact area and obtain the actual contact area of ​​the friction element.

[0014] Preferably, the process of obtaining the coordinate features of the actual contact area of ​​the friction element includes:

[0015] A polar coordinate system is established with the center of the friction element as the origin, the coordinate characteristics of the actual contact area are obtained, and m contact areas are obtained.

[0016] In the radial direction, the step size Δr of each radial coordinate node is l / 20, r1 and r2 are the inner and outer diameters of the friction element, respectively, l = r2 - r1, so i = r1, r1 + l / 20, r1 + l / 10, ..., r2;

[0017] In the circumferential direction, the step size Δθ of each circumferential angle coordinate node is π / 18, j = 0, π / 18, π / 9, ... The coordinates of the contact discrete point can be represented as Q(i,j), where i, j, k and n represent the coordinates in the r, θ, z and t directions, respectively, and Δr, Δθ, Δz and Δt represent the step size in each direction.

[0018] Let the circumferential central angle of the a-th contact region be θ. a The radial length is la, la = l2 - l1; where l1 and l2 are the coordinates of the start and end points of the radial direction of the contact area.

[0019] Preferably, the process of calculating the contact area of ​​the actual contact region based on the coordinate features and estimating the shape features of the actual contact region includes:

[0020] The a-th contact area:

[0021]

[0022] Preferably, the process of calculating the contact pressure of the actual contact area based on the contact area of ​​the actual contact area includes:

[0023] Calculate the sum of the contact areas of all contact regions:

[0024] Calculate the nominal contact area of ​​the friction element: S=π(r2) 2 -r1 2 );

[0025] Calculate the macroscopic contact ratio of the deformable friction element:

[0026] The formula for the contact pressure of the friction element is as follows:

[0027]

[0028] Where, p app This refers to the piston oil pressure.

[0029] Preferably, the process of obtaining the heat flux density distribution of the calculation region based on the contact pressure includes:

[0030] Based on the actual number of contact areas, the friction element is divided into m calculation regions; the calculation regions include contact areas and non-contact areas;

[0031] The heat flux density distribution of the computational region is then expressed as:

[0032] q(i,j,k)=μ·p(i,j,k)·ω rel (t)·r

[0033] In the formula, ω relω is the relative angular velocity of the clutch, and μ is the coefficient of friction.

[0034] Preferably, the process of determining the thermal boundary conditions of the contact region includes: determining the convective heat transfer boundary, heat flux density boundary, and adiabatic boundary of the computational region;

[0035] The thermal convection boundary conditions at the inner and outer diameters of the friction pair of the convective heat transfer boundary are as follows:

[0036] thermal convection

[0037] thermal convection

[0038] In the formula, T represents the temperature of the friction element. oil It is the ambient temperature; h i ρ and ho are the convective heat transfer coefficients at the inner and outer diameters, respectively; ρ, c and λ are the density, specific heat capacity and thermal conductivity of the friction element, respectively.

[0039] Within each computational region, the contact region corresponds to the heat flux density input region. Therefore, the boundary conditions for the heat flux density boundary are expressed as follows:

[0040]

[0041] In the formula, q is the heat flux density;

[0042] If the circumferential boundary of each computational region is an adiabatic boundary, then the boundary conditions of the adiabatic boundary are expressed as follows:

[0043]

[0044] Preferably, the process of calculating the temperature field characteristics of the actual contact area based on the heat flux density distribution of the calculation region includes:

[0045] The three-dimensional heat conduction equation of the friction element under intermittent contact state is solved by substituting the differential method into the equation, and the result is obtained.

[0046]

[0047] The three-dimensional heat conduction equation of the friction element under intermittent contact state is as follows:

[0048]

[0049] In the formula,

[0050] Substituting the thermal boundary conditions into the difference equation, we obtain... and S A1B1BA The heat transfer equation, and S DCBA The heat transfer equation and and The heat transfer equation;

[0051] The combined statement and The heat transfer equation, and S DCBA The heat transfer equation and and The heat transfer equation is solved to obtain the temperature field characteristics of each computational region of the friction element;

[0052] in, and The heat transfer equation is expressed as follows:

[0053]

[0054] In the formula,

[0055] and The heat transfer equation is expressed as follows:

[0056]

[0057] and The heat transfer equation is expressed as follows:

[0058]

[0059] The present invention also provides a device for calculating the equivalent temperature field of intermittent clutch contact, comprising:

[0060] The contact area acquisition module is used to acquire the friction element that has undergone warping deformation and to perform a static pressure test on the friction element to obtain the actual contact area of ​​the friction element.

[0061] A contact area acquisition module, connected to the contact region acquisition module, is used to acquire the coordinate features of the actual contact region of the friction element, calculate the contact area of ​​the actual contact region based on the coordinate features, and estimate the shape features of the actual contact region.

[0062] A contact pressure acquisition module, connected to the contact area acquisition module, is used to calculate the contact pressure of the actual contact area based on the contact area of ​​the actual contact area.

[0063] A heat flux density acquisition module, connected to the contact pressure acquisition module, is used to obtain the heat flux density distribution of the calculation area based on the contact pressure.

[0064] The temperature field feature acquisition module, connected to the heat flux density acquisition module, is used to determine the thermal boundary conditions of the contact area and calculate the temperature field features of the actual contact area based on the heat flux density distribution of the calculation area.

[0065] Compared with the prior art, the present invention has the following advantages and technical effects:

[0066] This invention provides a method and apparatus for calculating the equivalent temperature field of intermittent contact in a clutch. Considering the warping and deformation characteristics of clutch friction elements, the actual contact area and surface area of ​​the deformed friction elements are obtained through a press test. Subsequently, the actual contact pressure distribution characteristics between the deformed friction elements are obtained, leading to the actual intermittent contact temperature field between the friction elements. This method can calculate the temperature field characteristics of both uniform and intermittent contact states of the friction plates. Compared with existing technologies, the technology provided by this invention improves the accuracy and precision of clutch temperature field calculation, providing a theoretical basis for failure monitoring and evaluation of friction elements, and a technical foundation for condition-based clutch maintenance. It has significant reference value for clutch safety design, engagement control, and life assessment. Attached Figure Description

[0067] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0068] Figure 1 This is a schematic diagram of the method flow according to an embodiment of the present invention;

[0069] Figure 2 This is a schematic diagram of the three-dimensional difference format of the computational region in an embodiment of the present invention;

[0070] Figure 3 This is a schematic diagram of a friction element structure that has undergone warping deformation according to an embodiment of the present invention;

[0071] Figure 4 This is a schematic diagram of the actual contact area of ​​the friction element in an embodiment of the present invention;

[0072] Figure 5 This is a schematic diagram showing the shape characteristics of the actual contact area in an embodiment of the present invention;

[0073] Figure 6 This is a schematic diagram of the temperature field characteristics of an embodiment of the present invention with η = 0.81;

[0074] Figure 7 This is a schematic diagram of the temperature field characteristics of η=1 in an embodiment of the present invention. Detailed Implementation

[0075] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0076] It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions, and although a logical order is shown in the flowchart, in some cases the steps shown or described may be executed in a different order than that shown here.

[0077] Example 1

[0078] like Figure 1 As shown, this embodiment provides a method for calculating the equivalent temperature field of intermittent clutch contact, including:

[0079] Obtain the friction element that has already warped and deformed, and conduct a static pressure test on the friction element to obtain the actual contact area of ​​the friction element;

[0080] Obtain the coordinate characteristics of the actual contact area of ​​the friction element, calculate the contact area of ​​the actual contact area based on the coordinate characteristics, and estimate the shape characteristics of the actual contact area.

[0081] Calculate the contact pressure of the actual contact area based on the actual contact area, and obtain the heat flux density distribution of the calculated area based on the contact pressure.

[0082] The thermal boundary conditions of the contact area are determined, and the temperature field characteristics of the actual contact area are calculated based on the heat flux density distribution of the computational region.

[0083] Furthermore, by disassembling and inspecting the vehicle, friction components that have already warped and deformed can be obtained.

[0084] Furthermore, a static pressure test was conducted on the friction element. The test equipment included: a hydraulic press, a controller, FPD-8010E analysis software, pressure-sensitive test paper I and pressure-sensitive test paper II, a deformed friction element B, an intact friction element A, and pressure-sensitive test paper C.

[0085] The process of conducting a static pressure test on a friction element to obtain its actual contact area includes:

[0086] The pressure-sensitive test paper, deformable friction element, and complete friction element are stacked in the following order: complete friction element A, pressure-sensitive test paper I, deformable friction element B, pressure-sensitive test paper II, and complete friction element C are stacked in sequence to obtain a friction element combination;

[0087] The friction element assembly is placed on the shelf of the press, and the controller transmits a pressure signal to the press to apply pressure to the friction element assembly; the pressure applied by the press is the oil pressure value of the clutch under actual vehicle conditions.

[0088] After holding the pressure in the press for 1 minute, the pressure is released, and pressure test paper I and pressure test paper II are removed. The pressure test paper I and pressure test paper II are scanned using FPD-8010E analysis software to reveal the actual contact area and obtain the actual contact area of ​​the friction element.

[0089] Furthermore, the process of obtaining the coordinate characteristics of the actual contact area of ​​the friction element includes:

[0090] A polar coordinate system is established with the center of the friction element as the origin, the coordinate characteristics of the actual contact area are obtained, and m contact areas are obtained.

[0091] In the radial direction, the step size Δr of each radial coordinate node is l / 20, r1 and r2 are the inner and outer diameters of the friction element, respectively, l = r2 - r1, so i = r1, r1 + l / 20, r1 + l / 10, ..., r2;

[0092] In the circumferential direction, the step size Δθ of each circumferential angle coordinate node is π / 18, j = 0, π / 18, π / 9, ... The coordinates of the contact discrete point can be represented as Q(i,j), where i, j, k and n represent the coordinates in the r, θ, z and t directions, respectively, and Δr, Δθ, Δz and Δt represent the step size in each direction.

[0093] Let the circumferential central angle of the a-th contact region be θ. a The radial length is la, la = l2 - l1; where l1 and l2 are the coordinates of the start and end points of the radial direction of the contact area.

[0094] Furthermore, the process of calculating the contact area of ​​the actual contact region based on coordinate characteristics and estimating the shape characteristics of the actual contact region includes:

[0095] The a-th contact area:

[0096]

[0097] Furthermore, the process of calculating the contact pressure of the actual contact area based on the actual contact area includes:

[0098] Calculate the sum of the contact areas of all contact regions:

[0099] Calculate the nominal contact area of ​​the friction element: S=π(r2) 2 -r1 2 );

[0100] Calculate the macroscopic contact ratio of the deformable friction element:

[0101] The formula for the contact pressure of a friction element is:

[0102]

[0103] Where, p app This refers to the piston oil pressure.

[0104] Furthermore, the process of obtaining the heat flux density distribution of the computational region based on the contact pressure includes:

[0105] Based on the actual number of contact areas, the friction element is divided into m calculation regions; the calculation regions include contact areas and non-contact areas.

[0106] The heat flux density distribution in the computational domain is then expressed as:

[0107] q(i,j,k)=μ·p(i,j,k)·ω rel (t)·r

[0108] In the formula, ω rel ω is the relative angular velocity of the clutch, and μ is the coefficient of friction.

[0109] Furthermore, the process of determining the thermal boundary conditions of the contact region includes: determining the convective heat transfer boundary, heat flux density boundary, and adiabatic boundary of the computational region;

[0110] like Figure 2 The diagram shown illustrates the computational region. and These are the inner and outer diameters of the friction element, representing the convective heat transfer boundary surfaces. and S DCBA For heat flux density input surface, and It is an adiabatic boundary surface.

[0111] The thermal convection boundary conditions at the inner and outer diameters of the friction pair at the convection heat transfer boundary are as follows:

[0112] thermal convection

[0113] thermal convection

[0114] In the formula, T represents the temperature of the friction element. oil It is the ambient temperature; h iρ and ho are the convective heat transfer coefficients at the inner and outer diameters, respectively; ρ, c and λ are the density, specific heat capacity and thermal conductivity of the friction element, respectively.

[0115] Within each computational region, the contact region corresponds to the heat flux density input region. Therefore, the boundary conditions for the heat flux density boundary are expressed as follows:

[0116]

[0117] In the formula, q is the heat flux density;

[0118] If the circumferential boundary of each computational domain is an adiabatic boundary, then the boundary conditions of the adiabatic boundary are expressed as follows:

[0119]

[0120] Furthermore, the process of calculating the temperature field characteristics of the actual contact area based on the heat flux density distribution of the computational region includes:

[0121] The three-dimensional heat conduction equation of the friction element under intermittent contact state is solved by substituting the differential method into the equation, and the result is obtained.

[0122]

[0123] The three-dimensional heat conduction equation of the friction element under intermittent contact state is as follows:

[0124]

[0125] In the formula,

[0126] Substituting the thermal boundary conditions into the difference equation, we obtain... and The heat transfer equation, and S DCBA The heat transfer equation and and The heat transfer equation;

[0127] United and The heat transfer equation, and S DCBA The heat transfer equation and and S BB1C1C The heat transfer equation is solved to obtain the temperature field characteristics of each computational region of the friction element;

[0128] in, and The heat transfer equation is expressed as follows:

[0129]

[0130]

[0131] In the formula,

[0132] and S DCBA The heat transfer equation is expressed as follows:

[0133]

[0134] and The heat transfer equation is expressed as follows:

[0135]

[0136] It should be noted that this calculation method is also applicable to the temperature field calculation of friction elements under uniform contact conditions. Uniform contact is just a special case of this calculation method, namely the case where the contact rate η = 1.

[0137] This embodiment obtains the actual contact area of ​​the friction plate through experiments, characterizes it through coordinate nodes, and calculates the contact area of ​​each contact area to obtain the actual contact pressure. Based on the node characteristics of the actual contact area, a method for expressing the heat flux density of the contact area and the non-contact area is given. Considering the contact area, the friction element is divided into different calculation areas, thermal boundary conditions are established, and the temperature field of each calculation area is calculated to improve the accuracy of the clutch temperature field calculation. At the same time, this method is also applicable to uniform contact conditions.

[0138] Example 2

[0139] This embodiment also provides a method for calculating the equivalent temperature field of intermittent clutch contact, including:

[0140] 1. For example Figure 3 As shown, the test piece was obtained by disassembling and inspecting the vehicle during maintenance. The friction element that had already warped and deformed was obtained.

[0141] 2. For example Figure 4 As shown, the contact area of ​​the test piece is obtained: a static pressure test is performed on the deformable friction element. After the test, the pressure-sensitive test paper I and pressure-sensitive test paper II are post-processed. The FPD-8010E analysis software is used to scan the pressure-sensitive test paper to reveal the actual contact area and obtain the actual contact area of ​​the friction element.

[0142] 3. Quantify the contact characteristics of the test piece: Establish a polar coordinate system with the center of the friction element as the origin, obtain the coordinate characteristics of the actual contact area, and divide the contact area into 18 regions. r1 = 85mm, r2 = 125mm.

[0143] The coordinates of the contact discrete point can be represented as Q(i,j), where i, j, k, and n represent the step sizes in the r, θ, z, and t directions, respectively. Radially, the interval between each radial coordinate node is l / 20, where l = r2 - r1, so i = r1, r1 + l / 20, r1 + l / 10, ..., r2. Circumferentially, the interval between each circumferential angular coordinate node is π / 18, where j = 0, π / 18, π / 9, ...

[0144] 4. Calculate the contact area of ​​the contact region, by means of... Figure 5 The diagram shows the contact area, which is estimated to be fan-shaped. Taking the a-th contact area as an example... Measurements show that the circumferential central angle of the a-th contact area is... Radial length is l a =36mm, l1=87mm, l2=123mm.

[0145] 5. Calculate the contact pressure in the contact area:

[0146] Calculate the sum of the contact areas of all contact regions;

[0147] Calculate the nominal contact area of ​​the friction element: S=π(r2) 2 -r1 2 ) = 26376mm 2 ;

[0148] Calculate the macroscopic contact ratio of the deformable friction element: η = 0.81;

[0149] The clutch is in a state of low piston pressure, low relative speed, and prolonged slippage, with piston pressure p. app =0.12MPa, relative speed is 300r / min, and sliding time is 22s.

[0150]

[0151] 6. The calculated temperature field is as follows: Figure 6 As shown.

[0152] Example 3: Under the condition of uniform contact of the friction elements, the contact rate η = 1 in step 5, thus obtaining the temperature field as follows: Figure 7 As shown.

[0153] Example 4

[0154] This embodiment also provides a device for calculating the equivalent temperature field of intermittent clutch contact, including:

[0155] The contact area acquisition module is used to acquire friction elements that have undergone warping deformation and to perform static pressure tests on the friction elements to obtain the actual contact area of ​​the friction elements.

[0156] The contact area acquisition module, connected to the contact region acquisition module, is used to acquire the coordinate characteristics of the actual contact region of the friction element, calculate the contact area of ​​the actual contact region based on the coordinate characteristics, and estimate the shape characteristics of the actual contact region.

[0157] The contact pressure acquisition module is connected to the contact area acquisition module and is used to calculate the contact pressure of the actual contact area based on the actual contact area.

[0158] The heat flux density acquisition module is connected to the contact pressure acquisition module and is used to obtain the heat flux density distribution of the calculation area based on the contact pressure.

[0159] The temperature field feature acquisition module, connected to the heat flux density acquisition module, is used to determine the thermal boundary conditions of the contact area and calculate the temperature field features of the actual contact area based on the heat flux density distribution of the calculation area.

[0160] This invention provides a method and apparatus for calculating the equivalent temperature field of intermittent contact in a clutch. It considers the warping and deformation characteristics of clutch friction elements, quantifies the actual contact and sliding characteristics of deformed friction elements, and obtains the actual contact pressure distribution characteristics between deformed friction elements, thereby obtaining the actual intermittent contact temperature field between different friction elements. This provides a theoretical basis for the failure monitoring and evaluation of friction elements and a technical basis for condition-based maintenance of clutches.

[0161] The above are merely preferred embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for calculating the equivalent temperature field of intermittent clutch contact, characterized in that, include: Obtain a friction element that has already warped and deformed, and perform a static pressure test on the friction element to obtain the actual contact area of ​​the friction element; Obtain the coordinate features of the actual contact area of ​​the friction element, calculate the contact area of ​​the actual contact area based on the coordinate features, and estimate the shape features of the actual contact area. The contact pressure of the actual contact area is calculated based on the contact area of ​​the actual contact area, and the heat flux density distribution of the calculated area is obtained based on the contact pressure. Determine the thermal boundary conditions of the contact area, and calculate the temperature field characteristics of the actual contact area based on the heat flux density distribution of the calculated area. The process of calculating the temperature field characteristics of the actual contact area based on the heat flux density distribution of the computational region includes: By substituting the differential method into the three-dimensional heat conduction equation of the friction element under intermittent contact state, we obtain: The three-dimensional heat conduction equation of the friction element under intermittent contact state is as follows: In the formula, , , , ; Substituting the thermal boundary conditions into the difference equation, we obtain... and The heat transfer equation, and The heat transfer equation and and The heat transfer equation; The combined statement and The heat transfer equation, and The heat transfer equation and and The heat transfer equation is solved to obtain the temperature field characteristics of each computational region of the friction element; in, and The heat transfer equation is expressed as follows: In the formula, , ; and The heat transfer equation is expressed as follows: and The heat transfer equation is expressed as follows: 。 2. The method for calculating the equivalent temperature field of intermittent clutch contact according to claim 1, characterized in that, The process of performing a static pressure test on the friction element to obtain the actual contact area of ​​the friction element includes: The pressure-sensitive test paper, deformable friction element, and complete friction element are stacked in the following order: complete friction element A, pressure-sensitive test paper I, deformable friction element B, pressure-sensitive test paper II, and complete friction element C are stacked in sequence to obtain a friction element combination; The friction element assembly is placed on the shelf of the press, and a pressure signal is transmitted to the press through the controller to apply pressure to the friction element assembly; wherein, the pressure applied by the press is the oil pressure value of the clutch under actual vehicle conditions; After holding the pressure in the press for a preset time, the pressure is released, and the pressure-sensitive test paper I and pressure-sensitive test paper II are removed. The pressure-sensitive test paper I and pressure-sensitive test paper II are scanned using FPD-8010E analysis software to reveal the actual contact area and obtain the actual contact area of ​​the friction element.

3. The method for calculating the equivalent temperature field of intermittent clutch contact according to claim 1, characterized in that, The process of obtaining the coordinate features of the actual contact area of ​​the friction element includes: A polar coordinate system is established with the center of the friction element as the origin, the coordinate characteristics of the actual contact area are obtained, and m contact areas are obtained. In the radial direction, the step size of each radial coordinate node. for r1 and r2 are the inner and outer diameters of the friction element, respectively. Therefore, i = r1, r1 + r1+ , ..., r2; In the circumferential direction, the step size of each circumferential angle coordinate node. for j=0, , , ... The coordinates of the contact discrete point can be represented as Q(i, j), where i, j, k, and n represent the coordinates in the r, θ, z, and t directions, respectively. , , , This indicates the step size in each direction; Let the circumferential central angle of the a-th contact region be θ. a The radial length is la, la = l2 - l1; where l1 and l2 are the coordinates of the start and end points of the radial direction of the contact area.

4. The method for calculating the equivalent temperature field of intermittent clutch contact according to claim 1, characterized in that, The process of calculating the contact area of ​​the actual contact region based on the coordinate features and estimating the shape features of the actual contact region includes: The a-th contact area: 。 5. The method for calculating the equivalent temperature field of intermittent clutch contact according to claim 1, characterized in that, The process of calculating the contact pressure of the actual contact area based on the contact area of ​​the actual contact area includes: Calculate the sum of the contact areas of all contact regions: ; Calculate the nominal contact area of ​​the friction element: ; Calculate the macroscopic contact ratio of the deformable friction element: ; The formula for the contact pressure of the friction element is as follows: Where, p app This refers to the piston oil pressure.

6. The method for calculating the equivalent temperature field of intermittent clutch contact according to claim 1, characterized in that, The process of obtaining the heat flux density distribution of the computational region based on the contact pressure includes: Based on the actual number of contact areas, the friction element is divided into m calculation regions; the calculation regions include contact areas and non-contact areas; The heat flux density distribution of the computational region is then expressed as: In the formula, ω rel ω is the relative angular velocity of the clutch, and μ is the coefficient of friction.

7. The method for calculating the equivalent temperature field of intermittent clutch contact according to claim 1, characterized in that, The process of determining the thermal boundary conditions of the contact region includes: determining the convective heat transfer boundary, heat flux density boundary, and adiabatic boundary of the computational region. The thermal convection boundary conditions at the inner and outer diameters of the friction pair of the convective heat transfer boundary are as follows: In the formula, T represents the temperature of the friction element. oil It is the ambient temperature; h i ρ and ho are the convective heat transfer coefficients at the inner and outer diameters, respectively; ρ, c and λ are the density, specific heat capacity and thermal conductivity of the friction element, respectively. Within each computational region, the contact region corresponds to the heat flux density input region. Therefore, the boundary conditions for the heat flux density boundary are expressed as follows: In the formula, q is the heat flux density; If the circumferential boundary of each computational region is an adiabatic boundary, then the boundary conditions of the adiabatic boundary are expressed as follows: 。 8. A device for calculating the equivalent temperature field of intermittent clutch contact, used to implement the method according to any one of claims 1-7, characterized in that, include: The contact area acquisition module is used to acquire the friction element that has undergone warping deformation and to perform a static pressure test on the friction element to obtain the actual contact area of ​​the friction element. A contact area acquisition module, connected to the contact region acquisition module, is used to acquire the coordinate features of the actual contact region of the friction element, calculate the contact area of ​​the actual contact region based on the coordinate features, and estimate the shape features of the actual contact region. A contact pressure acquisition module, connected to the contact area acquisition module, is used to calculate the contact pressure of the actual contact area based on the contact area of ​​the actual contact area. A heat flux density acquisition module, connected to the contact pressure acquisition module, is used to obtain the heat flux density distribution of the calculation area based on the contact pressure. The temperature field feature acquisition module, connected to the heat flux density acquisition module, is used to determine the thermal boundary conditions of the contact area and calculate the temperature field features of the actual contact area based on the heat flux density distribution of the calculation area.

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