CN-119129134-B - Method and device for calculating intermittent contact equivalent temperature field of clutch

CN119129134BCN 119129134 BCN119129134 BCN 119129134BCN-119129134-B

Abstract

The invention discloses a clutch intermittent contact equivalent temperature field calculation method and device, which comprise the steps of obtaining a friction element which is subjected to buckling deformation, carrying out static pressure test on the friction element to obtain an actual contact area of the friction element, obtaining coordinate characteristics of the actual contact area of the friction element, calculating the contact area of the actual contact area according to the coordinate characteristics, estimating the 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, obtaining the heat flow density distribution of the calculation area according to the contact pressure, determining the heat boundary condition of the contact area, and calculating the temperature field characteristics of the actual contact area based on the heat flow density distribution of the calculation area. The invention improves the accuracy and precision of the calculation of the clutch temperature field, provides theoretical basis for failure monitoring and evaluation of the friction element, and has important reference significance for clutch safety design, combination control and life evaluation.

Inventors

YU LIANG
ZHENG CHANGSONG
CHEN MAN
ZHANG XIAOPENG
WEI CHENGSI
HE CHUNPING
LI HEYAN

Assignees

北京理工大学

Dates

Publication Date: 20260508
Application Date: 20240821

Claims (8)

1. A method for calculating an intermittent contact equivalent temperature field of a clutch, comprising: acquiring a friction element which has warp deformation, and carrying out a static pressure test on the friction element to obtain an actual contact area of the friction element; acquiring coordinate characteristics of an actual contact area of the friction element, calculating the 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; Determining a thermal boundary condition of a contact area, and calculating to obtain a temperature field characteristic of the actual contact area based on the heat flux density distribution of the calculation area; 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 comprises the following steps: And solving a three-dimensional heat conduction equation of the friction element in an intermittent contact state by adopting a differential mode to obtain: Wherein, the three-dimensional heat conduction equation of the friction element in the intermittent contact state is as follows: in the formula, , , , ; Bringing the thermal boundary conditions into a differential equation to obtain And A heat transfer equation of (2), And Heat transfer equation and of (2) And Is a heat transfer equation of (2); Simultaneous said And A heat transfer equation of (2), And Heat transfer equation and of (2) And Solving and obtaining the temperature field characteristics of each calculation area of the friction element; Wherein, the And The heat transfer equation expression of (2) is: in the formula, , ; And The heat transfer equation expression of (2) is: And The heat transfer equation expression of (2) is: 。
2. The method for calculating an intermittent contact equivalent temperature field for a clutch according to claim 1, wherein, Performing a static pressure test on the friction element, wherein the process for obtaining the actual contact area of the friction element comprises the following steps: The pressure sensing test paper, the deformation friction element and the complete friction element are sequentially overlapped, namely, the complete friction element A, the pressure sensing test paper I, the deformation friction element B, the pressure sensing test paper II and the complete friction element C are sequentially overlapped to obtain a friction element combination; the friction element combination is placed on a storage rack of a press machine, a pressure signal is transmitted to the press machine through a controller, and pressure is applied to the friction element combination, wherein the pressure value applied by the press machine is the oil pressure value of a clutch in a real vehicle state; And scanning the pressure sensing test paper I and the pressure sensing test paper II by using FPD-8010E analysis software, and displaying an actual contact area to obtain the actual contact area of the friction element.
3. The method for calculating an intermittent contact equivalent temperature field for a clutch according to claim 1, wherein, The process of acquiring the coordinate characteristics of the actual contact area of the friction element comprises the following steps: Establishing a polar coordinate system by taking the circle center of the friction element as a coordinate origin, acquiring coordinate characteristics of an actual contact area, and dividing to obtain m contact areas; step size of each radial coordinate node in radial direction Is that R 1 and r 2 are the inner and outer diameters of the friction element respectively, Therefore, i=r 1 ,r 1 + ,r 1 + ,......,r 2 ; In the circumferential direction, the step size of each circumferential angle coordinate node Is that ,j=0, , ,...... Wherein the coordinates of the discrete points of contact may be represented as Q (i, j), where i, j, k and n represent the coordinates in the r, θ, z and t directions, respectively, 、、、 Representing the step size in each direction; The circumferential central angle of the a-th contact area is set as theta a , the radial length is set as la, and la=l 2 -l 1 , wherein l 1 ,l 2 is the starting point and the end point coordinates of the contact area in the radial direction.
4. The method for calculating an intermittent contact equivalent temperature field for a clutch according to claim 1, wherein, Calculating the contact area of the actual contact area according to the coordinate features, and estimating the shape features of the actual contact area, wherein the process comprises the following steps: a-th contact area: 。
5. The method for calculating an intermittent contact equivalent temperature field for a clutch according to claim 1, wherein, The process of calculating the contact pressure of the actual contact area according to the contact area of the actual contact area comprises the following steps: The sum of the contact areas of all contact areas is calculated: ; calculating the nominal contact area of the friction element: ; Calculating the macroscopic contact rate of the deformed friction element: ; The contact pressure of the friction element has the formula: Wherein p app is the piston oil pressure.
6. The method for calculating an intermittent contact equivalent temperature field for a clutch according to claim 1, wherein, The process of obtaining the heat flux density distribution of the calculation region according to the contact pressure comprises the following steps: Dividing the friction element into m calculation areas according to the number of the actual contact areas, wherein the calculation areas comprise contact areas and non-contact areas; the heat flux density distribution of the calculated region is expressed as: Where ω rel is the relative angular velocity of the clutch and μ is the coefficient of friction.
7. The method for calculating an intermittent contact equivalent temperature field for a clutch according to claim 1, wherein, Determining thermal boundary conditions of a contact region includes determining a convective heat transfer boundary, a thermal flow density boundary, and an adiabatic boundary of the calculated region; the heat convection boundary conditions at the inner diameter and the outer diameter of the friction pair of the convection boundary are as follows: wherein T represents the temperature of the friction element, T oil is the ambient temperature, h i and ho are the convective heat transfer coefficients at the inner and outer diameters respectively, and ρ, c and λ are the density, specific heat capacity and thermal conductivity of the friction element respectively; in each calculation region, the contact region corresponds to the heat flux density input region, and then the boundary condition of the heat flux density boundary is expressed as: Wherein q is the heat flux density; the circumferential boundary of each calculation region is an adiabatic boundary, and the boundary condition of the adiabatic boundary is expressed as: 。
8. A clutch intermittent contact equivalent temperature field calculation device for implementing the method of any one of claims 1-7, comprising: the contact area acquisition module is used for acquiring the friction element which is subjected to buckling deformation, and carrying out a static pressure test on the friction element to obtain an actual contact area of the friction element; The contact area acquisition module is connected with the contact area acquisition module and is used for acquiring coordinate characteristics of an actual contact area of the friction element, calculating the contact area of the actual contact area according to the coordinate characteristics and estimating the shape characteristics of the actual contact area; the contact pressure acquisition module is connected with the contact area acquisition module and is used for calculating the contact pressure of the actual contact area according to the contact area of the actual contact area; The heat flux density acquisition module is connected with the contact pressure acquisition module and is used for acquiring heat flux density distribution of a calculation area according to the contact pressure; and the temperature field characteristic acquisition module is connected with the heat flux density acquisition module and is used for determining the heat boundary condition of the contact area and calculating and obtaining the temperature field characteristic of the actual contact area based on the heat flux density distribution of the calculation area.

Description

Method and device for calculating intermittent contact equivalent temperature field of clutch Technical Field The invention belongs to the technical field of automobile clutches, and particularly relates to a method and a device for calculating an intermittent contact equivalent temperature field of a clutch. Background The wet gear shifting clutch is widely applied to the transmission device of the vehicle by the advantages of strong unique bearing capacity, large transmission torque, simple structure and the like, and is a core component of various step-variable transmission devices. During wet clutch engagement, contact slip between the friction elements can generate a significant amount of frictional heat, resulting in a sudden increase in friction element temperature. However, excessive temperatures in the friction elements can exacerbate wear and even cause failure, affecting transmission reliability and ride-through. However, the scholars only research the temperature field characteristics of the perfect friction plate, and the patent CN202310335032.6 can determine the surface temperature of the wet clutch accurately according to the initial surface temperature at the initial time and the temperature rise and temperature drop. Patent CN202310332141.2 predicts the final temperature of the clutch based on the raw temperature value of the clutch, the temperature correction coefficient and the prediction Wen Shengliang. 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 buckling. Patent ZL202110576122.5 proposes a method and a device for acquiring a clutch temperature field based on a non-uniform pressure model, but only the contact non-uniformity of a friction element in the radial direction is considered, and the paper "study on the circumferential intermittent contact temperature field of the friction element of a gear shifting clutch" and the paper "study on saddle-shaped buckling deformation contact of a liquid viscosity friction pair and the temperature field distribution characteristic" all assume an ideal intermittent contact form of the friction element, and then the temperature field is calculated. In order to reveal the failure evolution process of the friction element, the failure of the friction element is precisely traced, the actual contact characteristics after the coarse failure deformation are required to be given, the actual temperature field characteristics and the influence thereof are calculated based on the actual contact characteristics, the failure state of the clutch can be timely monitored and evaluated in the actual vehicle driving process, and the maintenance measures according to conditions are provided in a targeted manner. Disclosure of Invention In order to solve the technical problems, the invention provides a method and a device for calculating an intermittent contact equivalent temperature field of a clutch. The method for calculating the intermittent contact equivalent temperature field of the clutch comprises the following steps: acquiring a friction element which has warp deformation, and carrying out a static pressure test on the friction element to obtain an actual contact area of the friction element; acquiring coordinate characteristics of an actual contact area of the friction element, calculating the 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; And determining a thermal boundary condition of a contact area, and calculating and obtaining the temperature field characteristics of the actual contact area based on the heat flow density distribution of the calculation area. Preferably, the static pressure test is performed on the friction element, and the process of obtaining the actual contact area of the friction element includes: The pressure sensing test paper, the deformation friction element and the complete friction element are sequentially overlapped, namely, the complete friction element A, the pressure sensing test paper I, the deformation friction element B, the pressure sensing test paper II and the complete friction element C are sequentially overlapped to obtain a friction element combination; the friction element combination is placed on a storage rack of a press machine, a pressure signal is transmitted to the press machine through a controller, and pressure is applied to the friction element combination, wherein the pressure value applied by the press machine is the oil pressure value of a clutch in a real v