Clutch intermittent contact equivalent temperature field calculation method and device

Abstract

The invention discloses a clutch intermittent contact equivalent temperature field calculation method and device, and the method comprises the steps: obtaining a friction element which is subjected to buckling deformation, and carrying out the static pressure test of the friction element, and obtaining an actual contact region of the friction element; acquiring coordinate characteristics of an actual contact area of the friction element, calculating a contact area of the actual contact area according to the coordinate characteristics, and estimating shape characteristics of the actual contact area; calculating the contact pressure of the actual contact area according to the contact area of the actual contact area, and obtaining the heat flux density distribution of the calculation area according to the contact pressure; thermal boundary conditions of the contact area are determined, and temperature field characteristics of the actual contact area are obtained through calculation based on heat flow density distribution of the calculation area. According to the method, the precision and accuracy of clutch temperature field calculation are improved, a theoretical basis is provided for failure monitoring and evaluation of friction elements, and the method has important reference significance for clutch safety design, combination control and service life evaluation.

Description

Technical Field

[0001] The invention belongs to the technical field of automobile clutches, and in particular relates to a method and device for calculating the intermittent contact equivalent temperature field of a clutch. Background Art

[0002] The wet shift clutch is widely used in vehicle transmissions due to its unique advantages such as strong load-bearing capacity, large torque transmission and simple structure. It is the core component of various step-speed transmissions. During the wet clutch engagement process, the contact and sliding between the friction elements will generate a large amount of friction heat, resulting in a sudden increase in the temperature of the friction elements. However, excessive temperature of the friction elements will increase wear and even cause failure, affecting the reliability and driving integrity of the transmission.

[0003] However, scholars have only studied the temperature field characteristics of intact friction plates. Patent CN202310335032.6 can determine a more accurate surface temperature of a wet clutch based on the starting surface temperature at the starting moment, as well as the temperature rise and temperature drop. Patent CN202310332141.2 predicts the final temperature of the clutch based on the original temperature value of the clutch, the temperature correction coefficient, and the 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, ignoring the temperature field characteristics of the friction elements after warping and deformation.

[0004] Patent ZL202110576122.5 proposes a clutch temperature field acquisition method and device based on a non-uniform pressure model, but only considers the radial contact non-uniformity of the friction element; the paper "Research on Circumferential Intermittent Contact Temperature Field of Shifting Clutch Friction Elements" and the paper "Research on Saddle-Shaped Buckling Deformation Contact and Temperature Field Distribution Characteristics of Liquid Viscous Friction Pairs" both assume the ideal intermittent contact form of the friction element and then calculate the temperature field. In order to reveal the failure evolution process of the friction element and accurately trace its failure, it is necessary to obtain the actual contact characteristics after the rough failure deformation, and based on this calculate the actual temperature field characteristics and their influence, so that the failure state of the clutch can be timely monitored and evaluated during the actual vehicle driving process, and targeted maintenance measures can be proposed according to the situation. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a method and device for calculating the intermittent contact equivalent temperature field of a clutch. A method for calculating the intermittent contact equivalent temperature field of a clutch comprises:

[0006] Obtaining a friction element that has undergone warping deformation, and performing a static pressure test on the friction element to obtain an actual contact area of ​​the friction element;

[0007] Acquiring coordinate features of the actual contact region of the friction element, calculating a contact area of ​​the actual contact region according to the coordinate features, and estimating a shape feature of the actual contact region;

[0008] Calculating the contact pressure of the actual contact area according to the contact area of ​​the actual contact area, and obtaining the heat flux density distribution of the calculation area according to 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 calculation 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, the deformed friction element, and the complete friction element are stacked in order: the complete friction element A, the pressure-sensitive test paper I, the deformed friction element B, the pressure-sensitive test paper II, and the complete friction element C are stacked in order to obtain a friction element combination;

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

[0013] After the press machine maintains the pressure for a preset time, the pressure is withdrawn and the pressure test papers I and II are removed; the pressure test papers I and II are scanned by FPD-8010E analysis software to visualize the actual contact area, thereby obtaining 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] Taking the center of the friction element as the coordinate origin, establishing a polar coordinate system, obtaining the coordinate characteristics of the actual contact area, and dividing it into m contact areas;

[0016] In the radial direction, the step length 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 length Δθ of each circumferential angle coordinate node is π / 18, j=0, π / 18, π / 9, ... The coordinates of the contact discrete points can be expressed 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 length in each direction;

[0018] Set the circumferential center angle of the ath contact area to θ a , the radial length is la, la=l2-l1; where l1, l2 are the starting and ending coordinates of the contact area in the radial direction.

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

[0020] The ath contact area:

[0021]

[0022] Preferably, the process of calculating the contact pressure of the actual contact area according to the contact area of ​​the actual contact area comprises:

[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 contact pressure of the friction element is expressed as follows:

[0027]

[0028] Among them, p app It is the piston oil pressure.

[0029] Preferably, the process of obtaining the heat flux density distribution of the calculation area according to the contact pressure includes:

[0030] According to the number of actual contact areas, the friction element is divided into m calculation areas; the calculation area includes a contact area and a non-contact area;

[0031] Then the heat flux distribution in the calculation area is expressed as:

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

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

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

[0035] Among them, the heat convection boundary conditions at the inner and outer diameters of the friction pair of the convection heat exchange boundary are:

[0036] Thermal convection

[0037] Thermal convection

[0038] Where, T represents the friction element temperature, T oil is the ambient temperature; h i , ho are the convection 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] In each calculation area, the contact area corresponds to the heat flux input area, and the boundary condition of the heat flux boundary is expressed as:

[0040]

[0041] Where q is the heat flux density;

[0042] The circumferential boundary of each calculation area is an adiabatic boundary, and the boundary condition of the adiabatic boundary is expressed as:

[0043]

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

[0045] Substituting the difference method into the three-dimensional heat conduction equation of the friction element under intermittent contact state for solution, we get

[0046]

[0047] Among them, the three-dimensional heat conduction equation of the friction element under intermittent contact state is:

[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 of

[0051] Combined 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 calculation area of ​​the friction element;

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

[0053]

[0054] In the formula,

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

[0056]

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

[0058]

[0059] The present invention also provides a clutch intermittent contact equivalent temperature field calculation device, comprising:

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

[0061] a contact area acquisition module, connected to the contact region acquisition module, for acquiring coordinate features of the actual contact region of the friction element, calculating the contact area of ​​the actual contact region according to the coordinate features, and estimating the shape features of the actual contact region;

[0062] a contact pressure acquisition module, connected to the contact area acquisition module, and configured to calculate the contact pressure of the actual contact area according to the contact area of ​​the actual contact area;

[0063] A heat flux density acquisition module, connected to the contact pressure acquisition module, for obtaining the heat flux density distribution of the calculation area according to the contact pressure;

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

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

[0066] The present invention provides a method and device for calculating the equivalent temperature field of intermittent contact of a clutch. The method takes into account the warping deformation characteristics of the clutch friction element, obtains the actual contact region and area of ​​the deformed friction element through a press test, and then obtains the actual contact pressure distribution characteristics between the deformed friction elements, and obtains the actual intermittent contact temperature field between the friction elements. This method can calculate the temperature field characteristics of the uniform contact state and the intermittent contact state of the friction plate. Compared with the prior art, the technology provided by the present invention improves the precision and accuracy of clutch temperature field calculation, provides a theoretical basis for failure monitoring and evaluation of friction elements, and provides a technical basis for condition-based maintenance of the clutch. It has important reference significance for clutch safety design, combination control, and life evaluation. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0068] Figure 1 A schematic diagram of a method flow of an embodiment of the present invention;

[0069] Figure 2 A schematic diagram of a three-dimensional difference format of a calculation area according to an embodiment of the present invention;

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

[0071] Figure 4 A schematic diagram of an actual contact area of ​​a friction element according to an embodiment of the present invention;

[0072] Figure 5 A schematic diagram of the shape characteristics of the actual contact area of ​​an embodiment of the present invention;

[0073] Figure 6 This is a characteristic diagram of the temperature field when η=0.81 in an embodiment of the present invention;

[0074] Figure 7 Schematic diagram of temperature field characteristics when η=1 in an embodiment of the present invention. DETAILED DESCRIPTION

[0075] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

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

[0077] Embodiment 1

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

[0079] Obtaining a friction element that has undergone warping deformation, and performing a static pressure test on the friction element to obtain an actual contact area of ​​the friction element;

[0080] Obtaining coordinate features of the actual contact region of the friction element, calculating the contact area of ​​the actual contact region according to the coordinate features, and estimating the shape features of the actual contact region;

[0081] The contact pressure of the actual contact area is calculated according to the contact area of ​​the actual contact area, and the heat flux density distribution of the calculation area is obtained according to 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 obtained based on the heat flux density distribution in the calculation area.

[0083] Furthermore, the friction element that has warped and deformed is obtained by means of vehicle maintenance and disassembly.

[0084] Furthermore, a static pressure test is performed on the friction element, and the test equipment includes: a hydraulic press, a controller, FPD-8010E analysis software, pressure test paper I and pressure test paper II, a deformed friction element B, a complete friction element A and a pressure test paper C.

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

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

[0087] The friction element assembly is placed on the rack 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 value applied by the press is the oil pressure value of the clutch in the actual vehicle state;

[0088] After the press machine maintains the pressure for 1 minute, the pressure is withdrawn and the pressure test papers I and II are removed; the pressure test papers I and II are scanned by the FPD-8010E analysis software to visualize the actual contact area and obtain the actual contact area of ​​the friction element.

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

[0090] Taking the center of the friction element as the coordinate origin, a polar coordinate system is established to obtain the coordinate characteristics of the actual contact area, and m contact areas are obtained by division;

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

[0092] In the circumferential direction, the step length Δθ of each circumferential angle coordinate node is π / 18, j=0, π / 18, π / 9, ... The coordinates of the contact discrete points can be expressed 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 length in each direction;

[0093] Set the circumferential center angle of the ath contact area to θ a , the radial length is la, la=l2-l1; where l1, l2 are the starting and ending coordinates of the contact area in the radial direction.

[0094] Furthermore, the contact area of ​​the actual contact region is calculated according to the coordinate features, and the process of estimating the shape features of the actual contact region includes:

[0095] The ath contact area:

[0096]

[0097] Furthermore, the process of calculating the contact pressure of the actual contact area according to the contact area of ​​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 the friction element is:

[0102]

[0103] Among them, p app It is the piston oil pressure.

[0104] Furthermore, the process of obtaining the heat flux density distribution in the calculation area according to the contact pressure includes:

[0105] According to the number of actual contact areas, the friction element is divided into m calculation areas; the calculation area includes the contact area and the non-contact area;

[0106] The heat flux distribution in the calculation area is expressed as:

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

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

[0109] Further, the process of determining the thermal boundary conditions of the contact region includes: determining a convection heat transfer boundary, a heat flux density boundary, and an adiabatic boundary of the calculation region;

[0110] like Figure 2 A schematic diagram of the calculation area is shown. and are the inner diameter and outer diameter convection heat transfer boundary surfaces of the friction element, and S DCBA is the heat flux input surface, and is an adiabatic boundary surface.

[0111] Among them, the thermal convection boundary conditions at the inner and outer diameters of the friction pair of the convection heat transfer boundary are:

[0112] Thermal convection

[0113] Thermal convection

[0114] Where, T represents the friction element temperature, T oil is the ambient temperature; h i, ho are the convection 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] In each calculation area, the contact area corresponds to the heat flux input area, and the boundary condition of the heat flux boundary is expressed as:

[0116]

[0117] Where q is the heat flux density;

[0118] The circumferential boundary of each calculation area is an adiabatic boundary, and the boundary condition of the adiabatic boundary is expressed as:

[0119]

[0120] Furthermore, the process of calculating and obtaining the temperature field characteristics of the actual contact area based on the heat flux density distribution in the calculation area includes:

[0121] Substituting the difference method into the three-dimensional heat conduction equation of the friction element under intermittent contact state for solution, we get

[0122]

[0123] Among them, the three-dimensional heat conduction equation of the friction element under intermittent contact state is:

[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 of

[0127] Lian Li 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 calculation area of ​​the friction element;

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

[0129]

[0130]

[0131] In the formula,

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

[0133]

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

[0135]

[0136] It should be noted that this calculation method is also applicable to the calculation of the temperature field of the friction element under uniform contact conditions. The uniform contact state is only a special case in this calculation method, that is, the case where the contact rate η=1.

[0137] This embodiment obtains the actual contact area of ​​the friction plate through an experimental method, characterizes it through coordinate nodes, and calculates the contact area of ​​each contact area, based on which the actual contact pressure is obtained; according to 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 calculation accuracy of the clutch temperature field; at the same time, this method is also applicable to uniform contact conditions.

[0138] Embodiment 2

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

[0140] 1. As Figure 3 As shown, the test piece is obtained: the friction element that has undergone warping and deformation is obtained by means of vehicle maintenance and disassembly.

[0141] 2. If Figure 4 As shown, the contact area of ​​the test piece is obtained: a static pressure test is performed on the deformed friction element, and after the test, the pressure-sensitive test paper I and the pressure-sensitive test paper II are post-processed, and the FPD-8010E analysis software is used to scan the pressure-sensitive test paper to visualize the actual contact area, thereby obtaining the actual contact area of ​​the friction element.

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

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

[0144] 4. Calculate the contact area of ​​the contact region by Figure 5 The schematic diagram of the contact area shown is that the estimated contact area is fan-shaped. Taking the a-th contact area as an example, Through measurement, it can be known that the circumferential center angle of the ath contact area is The 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 macro contact ratio of the deformed friction element: η = 0.81;

[0149] The clutch is in a state of low piston pressure, low relative speed and long-term sliding friction, and the piston pressure is p app =0.12MPa, relative speed is 300r / min, and sliding time is 22s.

[0150]

[0151] 6. Calculate the temperature field as Figure 6 shown.

[0152] Embodiment 3: Under the condition of uniform contact of the friction elements, the contact rate η in step 5 is 1, so that the temperature field is obtained as follows: Figure 7 shown.

[0153] Embodiment 4

[0154] This embodiment also provides a clutch intermittent contact equivalent temperature field calculation device, comprising:

[0155] A 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;

[0156] A contact area acquisition module, connected to the contact region acquisition module, is used to acquire coordinate features of the actual contact region of the friction element, calculate the contact area of ​​the actual contact region according to the coordinate features, and estimate the shape features of the actual contact region;

[0157] A contact pressure acquisition module, connected to the contact area acquisition module, for calculating the contact pressure of the actual contact area according to the contact area of ​​the actual contact area;

[0158] A 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 according to the contact pressure;

[0159] The temperature field characteristic acquisition module is connected to the heat flux density acquisition module and is used to determine the thermal boundary conditions of the contact area and obtain the temperature field characteristics of the actual contact area based on the heat flux density distribution calculation in the calculation area.

[0160] The present invention provides a method and device for calculating the intermittent contact equivalent temperature field of a clutch, which takes into account the warping deformation characteristics of the clutch friction element, quantifies the actual contact and sliding characteristics of the deformed friction element, obtains the actual contact pressure distribution characteristics between the deformed friction elements, and thus obtains the actual intermittent contact temperature field between different friction elements, providing a theoretical basis for failure monitoring and evaluation of the friction element, and providing a technical foundation for the condition-based maintenance of the clutch.

[0161] The above are only preferred specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for calculating the equivalent temperature field of intermittent contact of a clutch, characterized in that: include: Obtaining a friction element that has undergone warping deformation, and performing a static pressure test on the friction element to obtain an actual contact area of ​​the friction element; Acquiring coordinate features of the actual contact region of the friction element, calculating a contact area of ​​the actual contact region according to the coordinate features, and estimating a shape feature of the actual contact region; Calculating the contact pressure of the actual contact area according to the contact area of ​​the actual contact area, and obtaining the heat flux density distribution of the calculation area according to the contact pressure; 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 calculation area.

2. The clutch intermittent contact equivalent temperature field calculation method according to claim 1 is 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, the deformed friction element, and the complete friction element are stacked in order: the complete friction element A, the pressure-sensitive test paper I, the deformed friction element B, the pressure-sensitive test paper II, and the complete friction element C are stacked in order to obtain a friction element combination; The friction element assembly is placed on a rack of a press, and a pressure signal is transmitted to the press through a controller to apply pressure to the friction element assembly; wherein the pressure value applied by the press is the oil pressure value of the clutch in the actual vehicle state; After the press machine maintains the pressure for a preset time, the pressure is withdrawn and the pressure test papers I and II are removed; the pressure test papers I and II are scanned by FPD-8010E analysis software to visualize the actual contact area, thereby obtaining the actual contact area of ​​the friction element.

3. The clutch intermittent contact equivalent temperature field calculation method according to claim 1, characterized in that: The process of obtaining the coordinate features of the actual contact area of ​​the friction element includes: Taking the center of the friction element as the coordinate origin, establishing a polar coordinate system, obtaining the coordinate characteristics of the actual contact area, and dividing it into m contact areas; In the radial direction, the step length 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; In the circumferential direction, the step length Δθ of each circumferential angle coordinate node is The coordinates of the contact discrete points can be expressed 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 length in each direction; Set the circumferential center angle of the ath contact area to θ a , the radial length is la, la=l2-l1; where l1, l2 are the starting and ending coordinates of the contact area in the radial direction.

4. The clutch intermittent contact equivalent temperature field calculation method according to claim 1, characterized in that: The process of calculating the contact area of ​​the actual contact area according to the coordinate feature and estimating the shape feature of the actual contact area includes: The ath contact area:

5. The clutch intermittent contact equivalent temperature field calculation method according to claim 1, characterized in that: The process of calculating the contact pressure of the actual contact area according to the contact area of ​​the actual contact area comprises: Calculate the sum of the contact areas of all contact regions: Calculate the nominal contact area of ​​the friction element: S = π (r2 2 -r1 2 ); Calculate the macroscopic contact ratio of the deformable friction element: The contact pressure of the friction element is expressed as follows: Among them, p app It is the piston oil pressure.

6. The clutch intermittent contact equivalent temperature field calculation method according to claim 1, characterized in that: The process of obtaining the heat flux density distribution in the calculation area according to the contact pressure includes: According to the number of actual contact areas, the friction element is divided into m calculation areas; the calculation area includes a contact area and a non-contact area; Then the heat flux distribution in the calculation area is expressed as: q(i,j,k)=μ·p(i,j,k)·ω rel (t)·r In the formula, ω rel is the relative angular velocity of the clutch and μ is the friction coefficient.

7. The clutch intermittent contact equivalent temperature field calculation method according to claim 1, characterized in that: The process of determining the thermal boundary conditions of the contact region includes: determining the convection heat transfer boundary, the heat flux density boundary and the adiabatic boundary of the calculation region; Among them, the heat convection boundary conditions at the inner and outer diameters of the friction pair of the convection heat exchange boundary are: Thermal convection Thermal convection Where, T represents the friction element temperature, T oil is the ambient temperature; h i , ho are the convection 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; In each calculation area, the contact area corresponds to the heat flux input area, and the boundary condition of the heat flux boundary is expressed as: Where q is the heat flux density; The circumferential boundary of each calculation area is an adiabatic boundary, and the boundary condition of the adiabatic boundary is expressed as:

8. The clutch intermittent contact equivalent temperature field calculation method according to claim 1, characterized in that: The process of calculating and obtaining the temperature field characteristics of the actual contact area based on the heat flux density distribution of the calculation area includes: Substituting the difference method into the three-dimensional heat conduction equation of the friction element under intermittent contact state for solution, we get Among them, the three-dimensional heat conduction equation of the friction element under intermittent contact state is: In the formula, 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 of Combined 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 calculation area of ​​the friction element; in, and The heat transfer equation is expressed as: In the formula, and S DCBA The heat transfer equation is expressed as: and The heat transfer equation is expressed as:

9. A clutch intermittent contact equivalent temperature field calculation device, characterized in that: include: A contact area acquisition module, used to acquire a friction element that has undergone warping deformation, and perform a static pressure test on the friction element to obtain an actual contact area of ​​the friction element; a contact area acquisition module, connected to the contact region acquisition module, for acquiring coordinate features of the actual contact region of the friction element, calculating the contact area of ​​the actual contact region according to the coordinate features, and estimating the shape features of the actual contact region; a contact pressure acquisition module, connected to the contact area acquisition module, and configured to calculate the contact pressure of the actual contact area according to the contact area of ​​the actual contact area; A heat flux density acquisition module, connected to the contact pressure acquisition module, for obtaining the heat flux density distribution of the calculation area according to the contact pressure; The temperature field characteristic acquisition module is connected to the heat flux density acquisition module and is used to determine the thermal boundary conditions of the contact area and obtain the temperature field characteristics of the actual contact area based on the heat flux density distribution calculation of the calculation area.

Images