CN101980215A - I-type brake performance heat fading virtual test method for service brake system of biaxial automobile - Google Patents

Abstract

The invention discloses an I-type brake performance heat fading virtual test method for a service brake system of a biaxial automobile, which comprises the following steps of: 1, determining a functional relation mu=f(T) between the friction coefficient of a tested brake and the temperature, namely establishing a three-dimensional geometric model and a three-dimensional thermo-mechanical coupling finite element model and performing coupling temperature field simulation analysis on the established three-dimensional thermo-mechanical coupling finite element model to obtain the functional relation; 2, repeatedly raising the brake temperature of the brake system of the tested biaxial automobile and perform a virtual test on the friction performance of each shaft brake by the I-type brake performance heat fading virtual test method; and 3, performing a virtual test on heat fading braking efficiency after the tested biaxial automobile is repeatedly braked by the I-type brake performance heat fading virtual test method. The method has a reasonable design, low investment cost and good simulation effect, is convenient to operate and can overcome the defects of high cost, poor simulation performance, complex test method, long test period and the like in the conventional I-type brake performance heat fading virtual test system and the conventional I-type brake performance heat fading virtual test method.

Description

Diaxon running braking system I type braking ability heat fading virtual test method

Technical field

The present invention relates to a kind of braking ability heat fading virtual test method, especially relate to a kind of diaxon running braking system I type braking ability heat fading virtual test method.

Background technology

The practical work process more complicated of automotive brake, and detent is as important safety parts of automobile, its real work performance and stability not only is subjected to other non-car factor affecting in " people-Che-environment " system, also intercouples with other system of automobile and assembly simultaneously and acts on.Foundation for running braking system I type braking ability heat fading dummy experiment system, not only need be based on the combine friction factor temperature characterisitic of the detent that obtains of verifying of detent bench test and finite element simulation thereof, also need to take all factors into consideration under vehicle weight, the relevant component capabilities parameter role of geometry influence simultaneously, and manage to carry out error correction the dynamic output torque of detent with other.

The vehicle complete vehicle brake test is mainly the requirement whether checking meet corresponding regulations, standard and carries out, the state compulsory standard of vehicle complete vehicle braking aspect dominance mainly is GB12676-1999 " brake system of car structure, performance and test method " and GB7258-1997 " motor vehicle security of operation technical conditions ", wherein revised GB12676-1999 adopting by equivalent in 1999 ECE R13 rules and ISO 6597-1991, ISO7634-1995, international standards such as ISO7635-1991; GB7258 is according to the operating safety requirements of China's motor vehicle, is proposed and is come into effect in 1987 by the Ministry of Public Security, Ministry of Communications, does revision, the requirement of its 6th joint " braking system " and the content broadly similar of GB12676-1999 in 1997.The car load fade test that GB12676-1999 " brake system of car structure, performance and test method " relates to comprises: I type test (brake hard heat fading and recovery test) and II type test (long-slope experiment).Automobile real vehicle road brake test characteristics are true and reliable, generally carry out at proving ground, can simulate the actual applying working condition of some vehicles, be that automotive performance is studied indispensable basis and important step, but it need drop into more human and material resources and various surveying instrument, and expense and test period are still longer relatively; In addition sometimes because test condition and experimental safe aspect are considered also limited to some extent.And virtual test provides special efficient solution for automobile test.Virtual test is exactly to resolve by means of the high speed of computing machine, by the actual tests requirement realistic model based on the mathematical model of describing automotive system and dynamic process thereof is carried out simulation test: not only can be used as the preliminary preparation of true test or substitute traditional test (as some limiting conditions) to a certain extent; Significantly reduce true test number (TN), reduce testing expenses, shorten the test period; Interactivity makes various Test Information in time feed back preferably; Be not subjected to the restriction of meteorological condition, place, time and number of times, process of the test can conveniently realize playback, reproduction and repetition.

Summary of the invention

Technical matters to be solved by this invention is at above-mentioned deficiency of the prior art, a kind of diaxon running braking system I type braking ability heat fading virtual test method is provided, it is reasonable in design, the test cost of investment is low, simulate effect good and it is easy and simple to handle to use, and can effectively solve number of drawbacks and deficiency such as have the existing cost of investment height of braking system I type braking ability heat fading virtual measurement system and method now, simulation is relatively poor, test method is complicated, the test period is long.

For solving the problems of the technologies described above, the technical solution used in the present invention is: a kind of diaxon running braking system I type braking ability heat fading virtual test method is characterized in that this method may further comprise the steps:

Step 1, determine the funtcional relationship μ=f (T) between the friction factor-temperature of tested diaxon automotive brake brake friction pair, brake to be tested is drum brake or disc brake, and its deterministic process is as follows:

101, set up 3-D geometric model:, utilize CAD software to set up the 3-D geometric model of brake to be tested according to the assembly structure of brake to be tested;

102, set up three-dimensional heat-machine coupling finite element model, its modeling process is as follows:

1021,3-D geometric model described in the step 1 is imported in many coupling analysis softwares;

1022, under many coupling analysis software environments, select analytic unit and with selected analytic unit described 3-D geometric model is carried out grid dividing, selected analytic unit comprises 3D solid structural unit, rubbing contact unit and three types of unit of convection current radiating element of brake to be tested;

1023, that input is inquired according to the construction material handbook or the material property parameter by the measured brake to be tested of conventional material performance test test, select a kind of convergence rubbing contact algorithm fast, selected simultaneously friction factor-temperature model, finally set up three-dimensional heat-machine coupling finite element model, described friction factor-temperature model is the funtcional relationship μ=f (T) between the friction factor-temperature of brake to be tested brake friction pair, μ is the friction factor of brake to be tested brake friction pair in the formula, and T is the rubbing contact surface temperature of brake to be tested brake friction pair; Described material property parameter comprises elastic modulus, density, coefficient of heat conductivity, specific heat capacity, thermal expansivity and the Poisson ratio of brake to be tested material that brake friction pair adopts;

103, to the Temperature Field Simulation analysis that is coupled of the three-dimensional heat set up-machine coupling finite element model, selected one or more test points on the brake to be tested brake friction pair, to compare in Temperature Field Simulation result on each test point and the temperature test result who adopts conventional brake device temperature-raising experimental method to be tested on to each test point described three-dimensional heat-machine coupling finite element model, thereby the μ=f of funtcional relationship described in the step 3 (T) is verified, realization is carried out accurate identification to the coefficient among funtcional relationship μ=f (T), finally draws the funtcional relationship μ=f (T) between the friction factor-temperature of brake to be tested brake friction pair;

Step 2, utilize arithmetic processor and according to I type braking ability fade test method the temperature rise and the frictional behaviour of tested each shaft brake of diaxon automobile are carried out virtual test, its test process may further comprise the steps:

201, initial parameter is set, is calculated and storage: according to the operating condition of test that repeats to brake of automobile I type braking ability fade test method regulation, determine brake to be tested is carried out the test parameters of virtual test, comprise the initial velocity V of brake to be tested vehicle of living in ₀And this moment V ₀=constant v, automobile brake retarded velocity a ₀, brake to be tested initial temperature T ₀, cyclic brake number of times and braking period, and global cycle number of times m and cycle period t are set according to determined cyclic brake number of times and braking period; Afterwards, call parameters is provided with the structural parameters that described test parameters and automobile and detent are imported in the unit, simultaneously according to measuring accuracy and efficiency requirements setting-up time step delta t, and calculate the time total step number k=t/ Δ t of cyclic brake process each time, and with the V that is imported ₀, a ₀, m, t, Δ t, k, ω ₀And T ₀All deposit in the storage unit synchronously; Call parameters computing unit and simultaneously according to formula Calculate the initial angular velocity omegae of rotary part in the brake to be tested ₀, and with initial angular velocity omegae ₀Unloading is ω respectively _fAnd ω _rAfter deposit in the storage unit synchronously; Brake to be tested vehicle of living in is the diaxon automobile, and then described brake to be tested comprises front axle brake device that the front-wheel of diaxon automobile is braked and the rear brake that the trailing wheel of diaxon automobile is braked; Described rotary part is the brake drum of described drum brake or the brake disc of disc brake;

202, modeling: described arithmetic processor is learned system of equations according to automobile five degree of freedom brake power:

Set up the kinetic model of brake to be tested diaxon automobile of living in, the front-wheel of described diaxon automobile is identical with the radius of trailing wheel, ∑ F in the formula _X, ∑ F _Z, ∑ M _Y, ∑ M _WfWith ∑ M _WrBe respectively that automobile longitudinal is made a concerted effort, sprung mass is vertically made a concerted effort, sprung mass pitching resultant moment, front-wheel resultant moment and trailing wheel resultant moment; F _FbAnd F _RbBe the vertical ground force of calculating according to tire model, slip rate and wheel weight of automobile front and rear wheel; F _e, F _Fk, F _Fd, F _Rk, F _Rd, M _BfAnd M _BrBe respectively engine brake force, front suspension flexible member acting force, front suspension damping element acting force, rear suspension flexible member acting force, rear suspension damping element acting force, front axle brake device output torque and rear brake output torque, and above-mentioned variable is setting in advance on the basis of initial value and learns system of equations according to brake power and dynamically resolve; M, M _s, I _s, I _WfAnd I _WrBe respectively car mass, sprung mass, sprung mass is around barycenter moment of inertia, front-wheel moment of inertia and trailing wheel moment of inertia and set in step 201; A, b and r be respectively the automobile barycenter to front axle distance, barycenter is to the rolling radius of rear axle distance and wheel and set in step 201; a _X, a _SZ, ε _SY, ε _WfAnd ε _WrBe respectively automobile longitudinal acceleration, sprung mass vertical acceleration, sprung mass angle of pitch acceleration, front-wheel angular acceleration and trailing wheel angular acceleration, and above-mentioned variable resolves dynamically according to brake power system of equations;

When setting up described diaxon automobile dynamics model, with above-mentioned parameter respectively correspondence deposit in the storage unit and this moment in

The line pressure value of detent determines that its deterministic process is as follows when 203, continuing braking in the tested diaxon automobile brake heat fading cyclic process:

2031, call line pressure value determination module and carry out the definite of first time step Δ t inner brake line pressure value, its deterministic process is as follows:

20311, determine the line pressure incremental change Δ p of front axle brake device and rear brake earlier according to line pressure non-linear increasing rule _fWith Δ p _r, again according to formula p _If=p _0f+ Δ p _fAnd p _Ir=p _0r+ Δ p _r, calculate the line pressure p of the long Δ t of this time step front axle brake device and rear brake when finishing _IfAnd p _Ir, and with p _IfAnd p _IrUnloading is p respectively _fAnd p _r, the line pressure parameter in the storage unit is carried out real-time update, wherein p _0fAnd p _0rFor consumption is pressed in the release of tested diaxon automobile front axle detent and rear brake;

20312, according to the p that calculates in the step 20311 _fAnd p _r, calculate the output torque M of front axle brake device and rear brake _BfAnd M _Br, and the output torque parameter in the storage unit carried out real-time update;

20313, the engine brake force F described in the integrating step 202 _eAnd the vertical ground of automobile front and rear wheel directed force F _FbAnd F _Rb, and according to formula ∑ M _Wf=M _Bf-F _FbR=I _Wfε _WfWith

Calculate the angular deceleration ε of tested diaxon automobile front and back wheel _WfAnd ε _Wr, and the angular deceleration parameter in the storage unit carried out real-time update;

20314, call angular speed calculation module and according to formula ω _If=ω _f-ε _Wf* Δ t and ω _Ir=ω _r-ε _Wr* Δ t calculates the angular velocity omega of the long Δ t of this time step front axle brake device or rear brake when finishing _IfAnd ω _IrAnd unloading is ω _fAnd ω _rSo that the angular velocity parameter in the storage unit is carried out real-time update;

20315, according to formula ∑ F _X=-2 (F _Fb+ F _Rb)-F _e=-Ma _X, calculate the retarded velocity a of the long Δ t of this time step tested diaxon automobile when finishing _IXAnd unloading is a _XAgain according to formula V _I0=V ₀-a _XΔ t calculates the vehicle velocity V of the long Δ t of this time step tested diaxon automobile when finishing _I0And unloading is V ₀, so that the speed of a motor vehicle parameter in the storage unit is carried out real-time update;

20316, in conjunction with ω _f, ω _rAnd V ₀, and according to formula

With Calculate the slip rate s of front-wheel and trailing wheel _IfAnd s _IrAnd unloading is s respectively _fAnd s _rSo that the slip rate parameter in the storage unit is carried out real-time update;

20317, according to tire model and in conjunction with s _fAnd s _r, calculate the long Δ t of this time step vertical ground of automobile front and rear wheel directed force F when finishing _FbAnd F _RbAnd deposit in the storage unit synchronously, and the kinetic model of tackling in the step 202 mutually to be set up carries out real-time update;

20318, according to vehicle velocity V ₀And in conjunction with the engine brake force F that draws through conventional experimental test _eWith vehicle velocity V ₀Between funtcional relationship, calculate the long Δ t of this time step engine brake force F when finishing _eAnd deposit in the storage unit synchronously, and the kinetic model of tackling in the step 202 mutually to be set up carries out real-time update;

20319, judge | a _XWhether-3| less than δ, wherein δ=0.01～0.001: when | a _XDuring-3|＜δ, with the p that calculates in the step 20311 _fAnd p _rOutput also saves as p _MfAnd p _Mr, and with p _MfAnd p _MrThe line pressure value of front axle and rear brake when continuing braking in the braking heat fading cyclic process; Otherwise, enter step 2032;

2032, call line pressure value determination module and carry out the definite of next time step Δ t inner brake line pressure value, its deterministic process is as follows:

20321, determine the line pressure incremental change Δ p of front axle brake device and rear brake earlier according to line pressure non-linear increasing rule _fWith Δ p _r, again according to formula p _If=p _f+ Δ p _fAnd p _Ir=p _r+ Δ p _r, calculate the line pressure p of the long Δ t of this time step front axle brake device and rear brake when finishing _IfAnd p _IrAnd with p _IfAnd p _IrUnloading is p respectively _fAnd p _r, so that the line pressure parameter in the storage unit is carried out real-time update;

20322, again according to the p that calculates in the step 20321 _fAnd p _r, calculate the output torque M of front axle brake device and rear brake _BfAnd M _Br, and the output torque parameter in the storage unit carried out real-time update;

20323, the engine brake force F described in the integrating step 202 _eAnd the vertical ground of automobile front and rear wheel directed force F _FbAnd F _Rb, and according to formula ∑ M _Wf=M _Bf-F _FbR=I _Wfε _WfWith

Calculate the angular deceleration ε of tested diaxon automobile front and back wheel _WfAnd ε _Wr, and the angular deceleration parameter in the storage unit carried out real-time update;

20324, call angular speed calculation module and according to formula ω _If=ω _f-ε _Wf* Δ t and ω _Ir=ω _r-ε _Wr* Δ t calculates the angular velocity omega of the long Δ t of this time step front axle brake device or rear brake when finishing _IfAnd ω _Ir, and unloading is ω _fAnd ω _rSo that the angular velocity parameter in the storage unit is carried out real-time update;

20325, according to formula ∑ F _X=-2 (F _Fb+ F _Rb)-F _e=-Ma _X, calculate the retarded velocity a of the long Δ t of this time step tested diaxon automobile when finishing _IXAnd unloading is a _XAgain according to formula V _I0=V ₀-a _XΔ t calculates the vehicle velocity V of the long Δ t of this time step tested diaxon automobile when finishing _I0And unloading is V ₀, so that the speed of a motor vehicle parameter in the storage unit is carried out real-time update;

20326, in conjunction with ω _f, ω _rAnd V ₀, and according to formula

With

Calculate the slip rate s of front-wheel and trailing wheel _IfAnd s _IrAnd unloading is s respectively _fAnd s _r, so that the slip rate parameter in the storage unit is carried out real-time update;

20327, according to tire model and in conjunction with s _fAnd s _rCalculate the long Δ t of this time step vertical ground of automobile front and rear wheel directed force F when finishing _FbAnd F _RbAnd deposit in the storage unit synchronously, and the kinetic model of tackling in the step 202 mutually to be set up carries out real-time update;

20328, according to vehicle velocity V ₀And in conjunction with the engine brake force F that draws through conventional experimental test _eWith vehicle velocity V ₀Between funtcional relationship, calculate the long Δ t of this time step engine brake force F when finishing _eAnd deposit in the storage unit synchronously, and the kinetic model of tackling in the step 202 mutually to be set up carries out real-time update;

20329, judge | a _XWhether-3| less than δ, δ in the formula=0.01～0.001: when | a _XDuring-3|＜δ, with the p that calculates in the step 20321 _fAnd p _rOutput also saves as p _MfAnd p _Mr, and with p _MfAnd p _MrThe line pressure value of front axle and rear brake when continuing braking in the braking heat fading cyclic process; Otherwise, return step 20321;

204, cyclic brake: the kinetic model of the diaxon automobile of being set up in parameter that sets according to step 201 and the step 202, in the maximum pipeline pressure p that keeps front axle brake device and rear brake _f=p _MfAnd p _r=p _MrPrerequisite under, divide m time respectively to the braking heat fading process of described front axle brake device and the rear brake virtual test that circulates, the test process of its circulation virtual test is as follows:

2041, call the loop test module and carry out the test in first time step Δ t in the brake head fade test process, its process of the test is as follows:

20411, according to step 20311 to step 20318, calculate the angular velocity omega of the long Δ t of this time step front axle brake device and rear brake when finishing respectively _IfAnd ω _Ir, the vertical ground of automobile front and rear wheel directed force F _FbAnd F _RbAnd engine brake force F _e, and with the angular velocity omega of front axle brake device and rear brake _IfAnd ω _IrUnloading is ω respectively _fAnd ω _rAfter, the kinetic model of tackling in the step 202 mutually to be set up carries out real-time update;

20412, the detent temperature rise is calculated, and calls detent temperature rise computing module the transient behavior temperature T (t) of front axle brake device and rear brake in the long Δ t of this time step is calculated respectively, and its computation process is as follows:

20412a, according to formula p _Bf=M _Bfω _f, calculate front axle brake device and and the absorption braking power p of rear brake in the long Δ t of this time step _BfAnd p _Br, and the front axle brake device that will be tried to achieve this moment and the absorption braking power p of rear brake _BfAnd p _BrDeposit in synchronously in the described storage unit, the absorption braking power parameter in the described storage unit is carried out real-time update;

20412b, according to temperature variation differential equation P _Bf* dt-h * A[T (t)-T _E] dt=m * c * dT (t) and P _Br* dt-h * A[T (t)-T _E] dt=m * c * dT (t), solve the transient behavior temperature T (t) of interior front axle brake device of the long Δ t of this time step and rear brake respectively, and will this moment the front axle brake device that be tried to achieve and the transient behavior temperature T (t) of rear brake deposit in synchronously in the described storage unit, the transient behavior temperature parameter of front axle brake device in the described storage unit and rear brake is carried out real-time update; In the formula, h is the convection transfer rate of front axle brake device or rear brake, and m is the quality of the rotary part of front axle brake device or rear brake, and c is the specific heat of the material that rotary part adopts of front axle brake device or rear brake, T _EBe environment temperature;

20413, heat fading frictional behaviour is calculated: call heat fading frictional behaviour computing unit, according to the front axle brake device that calculates and the transient behavior temperature T (t) of rear brake among the funtcional relationship μ=f (T) of checking in the step 103 and the integrating step 20412b, corresponding calculate respectively front axle brake device and rear brake at this moment between hot coefficientoffriction in the step delta t _fAnd μ _rAnd corresponding depositing in the storage unit;

20414, call described parameter calculation unit, and according to the hot coefficientoffriction that calculates in the conventional computing method of braking efficiency factor and the integrating step 20413 _fAnd μ _r, calculate the usefulness factor BF of front axle brake device and rear brake in the long Δ t of this time step _fAnd BF _rAgain according to the conventional computing method of brake output torque, and in conjunction with the usefulness factor BF that is calculated this moment _fAnd BF _rWith front axle brake organ pipe road pressure p _fWith rear brake line pressure p _r, when corresponding reckoning draws the long Δ t of this time step and finishes, the output torque M of front axle brake device and rear brake _BfAnd M _Br, and with the usefulness factor BF that is calculated _fAnd BF _rAnd output torque M _BfAnd M _BrDeposit in synchronously in the described storage unit, braking efficiency factor in the described storage unit and output torque parameter are carried out real-time update; The diaxon automobile dynamics model of simultaneously, tackling in the step 203 mutually to be set up carries out real-time update;

20415, utilize the diaxon automobile dynamics model after the real-time update in the step 20414, and according to formula ∑ M _Wf=M _Bf-F _FbR=I _Wfε _Wf, the call parameters computing module calculates the front-wheel angular acceleration ε of the long Δ t of this time step when finishing _WfWith trailing wheel angular acceleration ε _Wr, and the front-wheel angular acceleration ε that will be calculated this moment _WfWith trailing wheel angular acceleration ε _WrDeposit in synchronously in the described storage unit, the front-wheel angular acceleration parameter in the described storage unit is carried out real-time update;

2042, call the loop test module and brake the test in next time step Δ t in the test process, its test process is as follows:

20421, according to step 20321 to step 20328, calculate the angular velocity omega of the long Δ t of this time step front axle brake device and rear brake when finishing respectively _IfAnd ω _Ir, the vertical ground of automobile front and rear wheel directed force F _FbAnd F _RbAnd engine brake force F _e, and with the angular velocity omega of front axle brake device and rear brake _IfAnd ω _IrUnloading is ω _fAnd ω _r, and the kinetic model of tackling in the step 202 mutually to be set up carries out real-time update;

20422, the detent temperature rise is calculated, and calls detent temperature rise computing module the transient behavior temperature T (t) of front axle brake device and rear brake in the long Δ t of this time step is calculated respectively, and its computation process is as follows:

20422a, according to formula p _Bf=M _Bfω _f, calculate front axle brake device and and the absorption braking power p of rear brake in the long Δ t of this time step _BfAnd p _Br, and the front axle brake device that will be tried to achieve this moment and the absorption braking power p of rear brake _BfAnd p _BrDeposit in synchronously in the described storage unit, the absorption braking power parameter in the described storage unit is carried out real-time update;

20422b, according to temperature variation differential equation P _Bf* dt-h * A[T (t)-T _E] dt=m * c * dT (t) and P _Br* dt-h * A[T (t)-T _E] dt=m * c * dT (t), solve the transient behavior temperature T (t) of interior front axle brake device of the long Δ t of this time step and rear brake respectively, and will this moment the front axle brake device that be tried to achieve and the transient behavior temperature T (t) of rear brake deposit in synchronously in the described storage unit, the transient behavior temperature parameter of front axle brake device in the described storage unit and rear brake is carried out real-time update; In the formula, h is the convection transfer rate of front axle brake device or rear brake, and m is the quality of the rotary part of front axle brake device or rear brake, and c is the specific heat of the material that rotary part adopts of front axle brake device or rear brake, T _EBe environment temperature;

20423, heat fading frictional behaviour is calculated: call heat fading frictional behaviour computing unit, according to the front axle brake device that calculates and the transient behavior temperature T (t) of rear brake among the funtcional relationship μ=f (T) of checking in the step 103 and the integrating step 20412b, corresponding calculate respectively front axle brake device and rear brake at this moment between hot coefficientoffriction in the step delta t _fAnd μ _rAnd corresponding depositing in the storage unit;

20424, call described parameter calculation unit, and according to the hot coefficientoffriction that calculates in the conventional computing method of braking efficiency factor and the integrating step 20423 _fAnd μ _r, calculate the usefulness factor BF of front axle brake device and rear brake in the long Δ t of this time step _fAnd BF _rAgain according to the conventional computing method of brake output torque, and in conjunction with the usefulness factor BF that is calculated this moment _fAnd BF _rWith front axle brake organ pipe road pressure p _fWith rear brake line pressure p _r, when corresponding reckoning draws the long Δ t of this time step and finishes, the output torque M of front axle brake device and rear brake _BfAnd M _Br, and with the usefulness factor BF that is calculated _fAnd BF _rAnd output torque M _BfAnd M _BrDeposit in synchronously in the described storage unit, braking efficiency factor in the described storage unit and output torque parameter are carried out real-time update; The diaxon automobile dynamics model of simultaneously, tackling in the step 203 mutually to be set up carries out real-time update;

20425, utilize the diaxon automobile dynamics model after the real-time update in the step 20424, and according to formula ∑ M _Wf=M _Bf-F _FbR=I _Wfε _Wf, the call parameters computing module calculates the front-wheel angular acceleration ε of the long Δ t of this time step when finishing _WfWith trailing wheel angular acceleration ε _Wr, and the front-wheel angular acceleration ε that will be calculated this moment _WfWith trailing wheel angular acceleration ε _WrDeposit in synchronously in the described storage unit, front-wheel angular acceleration parameter in the described storage unit and trailing wheel angular acceleration parameter are carried out real-time update;

When 20426, this time step Δ t finishes, to the vehicle velocity V of the tested diaxon automobile after upgrading in the current described storage unit ₀Judge: when

The time, return step 2042, proceed the experimental test in next the time step Δ t in the brake test process, so constantly circulation; When

The time, the brake test process of finishing in this fade test's virtual test process is described, then enter step 2043, the used time step number of brake test process is n among this fade test at this moment ₁

2043, the brake temperature in detent speed-raising heat radiation stage calculates, and its computation process is as follows:

20431, call the calculating in first time step Δ t in the speed-raising heat radiation computation process that circulates of detent speed-raising radiating module, its computation process is as follows:

20431a, according to formula-h * A[T (t)-T _E] dt=m * c * dT (t), the transient behavior temperature T (t) that solves interior front axle brake device of the long Δ t of this time step and rear brake also deposits in the described storage unit synchronously, and the temperature parameter in the described storage unit is carried out real-time update, T in the formula _EBe environment temperature, h is the convection transfer rate of front axle brake device or rear brake, m _BfBe the quality of the rotary part of front axle brake device or rear brake, c is the specific heat of the material that rotary part adopts of front axle brake device or rear brake;

20431b, speed-raising heat radiation frictional behaviour are calculated: according to the front axle brake device that calculates among the funtcional relationship μ=f (T) of checking in the step 103 and the integrating step 20431a and the transient behavior temperature T (t) of rear brake, calculate front axle brake device and rear brake at this moment between hot coefficientoffriction in the step delta t _fAnd μ _r, and corresponding depositing in the storage unit;

20432, call the calculating in the next time step Δ t in the speed-raising heat radiation computation process that circulates of detent speed-raising radiating module, its computation process is as follows:

20432a, according to formula-h * A[T (t)-T _E] dt=m * c * dT (t), the transient behavior temperature T (t) that solves interior front axle brake device of the long Δ t of this time step and rear brake also deposits in the described storage unit synchronously, and the temperature parameter in the described storage unit is carried out real-time update;

20432b, speed-raising heat radiation frictional behaviour are calculated: according to the front axle brake device that calculates among the funtcional relationship μ=f (T) of checking in the step 103 and the integrating step 20432a and the transient behavior temperature T (t) of rear brake, calculate front axle brake device and rear brake at this moment between hot coefficientoffriction in the step delta t _fAnd μ _r, and corresponding depositing in the storage unit;

20433, return step 20432, the calculating of next time step Δ t in the speed-raising heat radiation computation process of proceeding to circulate constantly repeats and through m ₁=(t-n ₁* Δ t)/Δ t time step enters step 20434 after calculating, and the used time step number of speed-raising heat radiation computation process is m among this fade test ₁

2044, repeating step 2041 until finishing heat fading performance circulation virtual test m time, is then finished the temperature rise and the frictional behaviour virtual test process of described tested diaxon automobile front axle detent and rear brake to step 2043;

Step 2 is carried out in the virtual test process, export all computational datas of being stored in the described storage unit by the display that joins with described arithmetic processor and show synchronously, this moment, the temperature rise and the frictional behaviour virtual test process of tested each shaft brake of diaxon automobile finished.

Above-mentioned diaxon running braking system I type braking ability heat fading virtual test method, it is characterized in that: after finishing the temperature rise and frictional behaviour virtual test process of described tested diaxon automobile front axle detent in the step 2044, also need utilize arithmetic processor and according to I type braking ability fade test method tested diaxon automobile is repeated to brake after the heat fading brake efficiency carry out virtual test, its test process may further comprise the steps:

301, initial parameter is set and storage: the heat fading brake efficiency after according to I type braking ability fade test method tested diaxon automobile being repeated to brake carries out the operating condition of test of virtual test, determine tested diaxon automobile is carried out the test parameters of virtual test, comprise the initial velocity V of brake to be tested vehicle of living in ₂And deposit in the storage unit synchronously;

302, the diaxon automobile dynamics model that utilizes in the step 202 to be set up, calculating at initial velocity is V ₂And the automobile brake distance and the braking deceleration of described diaxon automobile under the state that stops in emergency;

Carry out in the step 302 in the virtual test process, export all computational datas of being stored in the described storage unit by the display that joins with described arithmetic processor, tide of motorism decline brake efficiency test process finishes.

Above-mentioned diaxon running braking system I type braking ability heat fading virtual test method, it is characterized in that: many coupling analysis softwares described in the step 1021 are ADINA software.

Above-mentioned diaxon running braking system I type braking ability heat fading virtual test method is characterized in that: the conventional brake device temperature-raising experimental method described in the step 103 is for the constant speed temperature-raising experimental method that adopts the chassis multi-function test stand detent rear axle assy is carried out or adopt on the brake tester described brake assembly is carried out the constant speed temperature-raising experimental method.

The present invention compared with prior art has the following advantages:

1, reasonable in design, easy and simple to handle and realize conveniently, obviously simplified diaxon running braking system I type braking ability fade test's process of the test, greatly the shortening test period, significantly reduce experimentation cost.

2, computational accuracy is higher.

3, practical value height, during the easy input commercial production of energy is used, can in the brake producing process, be used to carry out the assessment and the monitoring of braking ability easily, can be economical, efficiently links such as the design of detent, production, evaluation, sale are carried out the real-time follow-up test, not only guarantee product quality, also can in time adjust the every performance index of product, strengthen the flexibility of production.

4, popularizing application prospect is extensive, meets current China diaxon auto brake system I type braking ability heat fading virtual test industry to the desired target call the most effective, the most accurate, that save most of method of testing.

5, widely applicable, can be advantageously used in the single factor of automobile brake heat fading and friction performance of brake heat fading or the virtual test of aspects such as multiplicity, limiting condition analysis are detected research.

In sum, the present invention is reasonable in design, the test cost of investment is low, simulate effect good and it is easy and simple to handle to use, and can effectively solve number of drawbacks and deficiency such as have the existing cost of investment height of braking system I type braking ability heat fading virtual measurement system and method now, simulation is relatively poor, test method is complicated, the test period is long.

Below by drawings and Examples, technical scheme of the present invention is described in further detail.

Description of drawings

Fig. 1 is a test method process flow diagram of the present invention.

Embodiment

A kind of diaxon running braking system I type braking ability heat fading virtual test method as shown in Figure 1 may further comprise the steps:

Step 1, determine the funtcional relationship μ=f (T) between the friction factor-temperature of tested diaxon automotive brake brake friction pair, brake to be tested is drum brake or disc brake, and its deterministic process is as follows:

101, set up 3-D geometric model:, and adopt CAD software to set up the 3-D geometric model of brake to be tested according to the assembly structure of brake to be tested;

102, set up three-dimensional heat-machine coupling finite element model, its modeling process is as follows:

1021,3-D geometric model described in the step 1 is imported in many coupling analysis softwares; In the present embodiment, described many coupling analysis softwares are ADINA software;

1022, under many coupling analysis software environments, select analytic unit and with selected analytic unit described 3-D geometric model is carried out grid dividing, selected analytic unit comprises 3D solid structural unit, rubbing contact unit and three types of unit of convection current radiating element of brake to be tested;

1023, input (is specially by heptan of horse and " modern project material handbook one book of appointing mound cypress chief editor according to the construction material handbook, the also associated materials handbook that can use with reference to routine) that inquired or the material property parameter by the measured brake to be tested of conventional material performance test test, select a kind of convergence rubbing contact algorithm fast, selected simultaneously friction factor-temperature model, finally set up three-dimensional heat-machine coupling finite element model, described friction factor-temperature model is the funtcional relationship μ=f (T) between the friction factor-temperature of brake to be tested brake friction pair, μ is the friction factor of brake to be tested brake friction pair in the formula, and T is the rubbing contact surface temperature of brake to be tested brake friction pair; Described material property parameter comprises elastic modulus, density, coefficient of heat conductivity, specific heat capacity, thermal expansivity and the Poisson ratio of brake to be tested material that brake friction pair adopts;

103, to the Temperature Field Simulation analysis that is coupled of the three-dimensional heat set up-machine coupling finite element model, selected one or more test points on the brake to be tested brake friction pair, to compare in Temperature Field Simulation result on each test point and the temperature test result who adopts conventional brake device temperature-raising experimental method to be tested on to each test point described three-dimensional heat-machine coupling finite element model, thereby the μ=f of funtcional relationship described in the step 3 (T) is verified, realization is carried out accurate identification to the coefficient among funtcional relationship μ=f (T), finally draws the funtcional relationship μ=f (T) between the friction factor-temperature of brake to be tested brake friction pair;

In the present embodiment, described conventional brake device temperature-raising experimental method is for the constant speed temperature-raising experimental method that adopts the chassis multi-function test stand detent rear axle assy is carried out or adopt on the brake tester described brake assembly is carried out the constant speed temperature-raising experimental method.

In the present embodiment, brake to be tested vehicle of living in is the diaxon automobile, and brake to be tested comprises front axle brake device and rear brake, then needs in the step 1 respectively the funtcional relationship μ=f (T) between the friction factor-temperature of the brake friction pair of front axle brake device and rear brake is determined respectively.

Step 2, utilize arithmetic processor and according to I type braking ability fade test method the temperature rise and the frictional behaviour of tested each shaft brake of diaxon automobile are carried out virtual test, its test process may further comprise the steps:

201, initial parameter is set, is calculated and storage: according to the operating condition of test that repeats to brake of automobile I type braking ability fade test method regulation, determine brake to be tested is carried out the test parameters of virtual test, comprise the initial velocity V of brake to be tested vehicle of living in ₀And this moment V ₀=constant v, automobile brake retarded velocity a ₀, brake to be tested initial temperature T ₀, cyclic brake number of times and braking period, and global cycle number of times m and cycle period t are set according to determined cyclic brake number of times (promptly repeating to brake number of times) and braking period; Afterwards, call parameters is provided with the structural parameters that described test parameters and automobile and detent are imported in the unit, simultaneously according to measuring accuracy and efficiency requirements setting-up time step delta t, and calculate the time total step number k=t/ Δ t of cyclic brake process each time, and with the V that is imported ₀, a ₀, m, t, Δ t, k, ω ₀And T ₀All deposit in the storage unit synchronously; Call parameters computing unit and simultaneously according to formula

Calculate the initial angular velocity omegae of rotary part in the brake to be tested ₀, and with initial angular velocity omegae ₀Unloading is ω respectively _fAnd ω _rAfter deposit in the storage unit synchronously; Brake to be tested vehicle of living in is the diaxon automobile, and then described brake to be tested comprises front axle brake device that the front-wheel of diaxon automobile is braked and the rear brake that the trailing wheel of diaxon automobile is braked; Described rotary part is the brake drum of described drum brake or the brake disc of disc brake.

In the actual use, can by call parameters the structural parameters that described test parameters and automobile and detent are imported in the unit be set according to concrete needs.

202, modeling: described arithmetic processor is learned system of equations according to automobile five degree of freedom brake power:

Set up the kinetic model of brake to be tested diaxon automobile of living in, the front-wheel of described diaxon automobile is identical with the radius of trailing wheel, ∑ F in the formula _X, ∑ F _Z, ∑ M _Y, ∑ M _WfWith ∑ M _WrBe respectively that automobile longitudinal is made a concerted effort, sprung mass is vertically made a concerted effort, sprung mass pitching resultant moment, front-wheel resultant moment and trailing wheel resultant moment; F _FbAnd F _RbFor calculate according to tire model the vertical ground force of automobile front and rear wheel; F _e, F _Fk, F _Fd, F _Rk, F _Rd, M _BfAnd M _BrBe respectively engine brake force (its size and relating to parameters such as the speed of a motor vehicle of detected automobile, gear), front suspension flexible member acting force, front suspension damping element acting force, rear suspension flexible member acting force, rear suspension damping element acting force, front axle brake device output torque and rear brake output torque, and above-mentioned variable is setting in advance and learns system of equations according to brake power on the basis of initial value and dynamically resolve; M, M _s, I _s, I _WfAnd I _WrBe respectively car mass, sprung mass, sprung mass is around barycenter moment of inertia, front-wheel moment of inertia and trailing wheel moment of inertia and set in step 201; A, b and r be respectively the automobile barycenter to front axle distance, barycenter is to the rolling radius of rear axle distance and wheel and set in step 201; a _X, a _SZ, ε _SY, ε _WfAnd ε _WrBe respectively automobile longitudinal acceleration, sprung mass vertical acceleration, sprung mass angle of pitch acceleration, front-wheel angular acceleration and trailing wheel angular acceleration, and above-mentioned variable resolves dynamically according to brake power system of equations.

When setting up described diaxon automobile dynamics model, with above-mentioned parameter respectively correspondence deposit in the storage unit and this moment in

When reality was calculated moment of inertia I, for two-axle car (three cars that contain two rear axles), the moment of inertia I that its front axle brake device and driving shaft detent are born was respectively:

$I_f=\frac{\mathrm{\β}}{1+\mathrm{\β}}\×\frac{(G_a+7\%G_0)r^2}{2g}\mathrm{kg}\·m\·s^2,$ $I_{\mathrm{dr}}=\frac{1}{1+\mathrm{\β}}\×\frac{(G_a+7\%G_0)r^2}{2g}\mathrm{kg}\·m\·s^2.$ If three cars of two rear axles, the moment of inertia I that its rear brake should bear is

$I_{\mathrm{dr}}=\frac{1}{2}{I}_r$

I in the formula _f, I _r, I _Dr-be respectively three moment of inertia that the car rear brake should bear of forward and backward shaft brake and two rear axles, kgms ²

β-antero posterior axis braking-force ratio, for three cars of two rear axles, two back axle braking force sums are as the back axle braking force;

G ₀, G _a, r, g-be respectively the fully loaded gross mass (kg) of automobile empty wagons gross mass (kg), automobile, vehicle wheel roll radius (m), acceleration of gravity (m/s ²).

The line pressure value of detent determines that its deterministic process is as follows when 203, continuing braking in the tested diaxon automobile brake heat fading cyclic process:

2031, call line pressure value determination module and carry out the definite of first time step Δ t inner brake line pressure value, its deterministic process is as follows:

20311, determine the line pressure incremental change Δ p of front axle brake device and rear brake earlier according to line pressure non-linear increasing rule _fWith Δ p _r, again according to formula p _If=p _0f+ Δ p _fAnd p _Ir=p _0r+ Δ p _r, calculate the line pressure p of the long Δ t of this time step front axle brake device and rear brake when finishing _IfAnd p _Ir, and with p _IfAnd p _IrUnloading is p respectively _fAnd p _r, the line pressure parameter in the storage unit is carried out real-time update, wherein p _0fAnd p _0rFor consumption is pressed in the release of tested diaxon automobile front axle detent and rear brake;

20312, according to the p that calculates in the step 20311 _fAnd p _r, calculate the output torque M of front axle brake device and rear brake _BfAnd M _Br(specifically calculating) according to the funtcional relationship between brake output torque and the line pressure, and the output torque parameter in the storage unit carried out real-time update;

20313, the engine brake force F described in the integrating step 202 _eAnd the vertical ground of automobile front and rear wheel directed force F _FbAnd F _Rb, and according to formula ∑ M _Wf=M _Bf-F _FbR=I _Wfε _WfWith Calculate the angular deceleration ε of tested diaxon automobile front and back wheel _WfAnd ε _Wr, and the angular deceleration parameter in the storage unit carried out real-time update;

20314, call angular speed calculation module and according to formula ω _If=ω _f-ε _Wf* Δ t and ω _Ir=ω _r-ε _Wr* Δ t calculates the angular velocity omega of the long Δ t of this time step front axle brake device or rear brake when finishing _IfAnd ω _Ir, and unloading is ω _fAnd ω _rSo that the angular velocity parameter in the storage unit is carried out real-time update;

20315, according to formula ∑ F _X=-2 (F _Fb+ F _Rb)-F _e=-Ma _X, calculate the retarded velocity a of the long Δ t of this time step tested diaxon automobile when finishing _IXAnd unloading is a _XAgain according to formula V _I0=V ₀-a _XΔ t calculates the vehicle velocity V of the long Δ t of this time step tested diaxon automobile when finishing _I0And unloading is V ₀, so that the speed of a motor vehicle parameter in the storage unit is carried out real-time update;

20316, in conjunction with ω _f, ω _rAnd V ₀, and according to formula

With

Calculate the slip rate s of front-wheel and trailing wheel _IfAnd s _IrAnd unloading is s respectively _fAnd s _rSo that the slip rate parameter in the storage unit is carried out real-time update;

20317, according to tire model and in conjunction with s _fAnd s _r, calculate the long Δ t of this time step vertical ground of automobile front and rear wheel directed force F when finishing _FbAnd F _RbAnd deposit in the storage unit synchronously, and the kinetic model of tackling in the step 202 mutually to be set up carries out real-time update;

20318, according to vehicle velocity V ₀And in conjunction with the engine brake force F that draws through conventional experimental test _eWith vehicle velocity V ₀Between funtcional relationship, calculate the long Δ t of this time step engine brake force F when finishing _eAnd deposit in the storage unit synchronously, and the kinetic model of tackling in the step 202 mutually to be set up carries out real-time update;

20319, judge | a _XWhether-3| less than δ, wherein δ=0.01～0.001: when | a _XDuring-3|＜δ, with the p that calculates in the step 20311 _fAnd p _rOutput also saves as p _MfAnd p _Mr, and with p _MfAnd p _MrThe line pressure value of front axle and rear brake when continuing braking in the braking heat fading cyclic process; Otherwise, enter step 2032;

2032, call line pressure value determination module and carry out the definite of next time step Δ t inner brake line pressure value, its deterministic process is as follows:

20321, determine the line pressure incremental change Δ p of front axle brake device and rear brake earlier according to line pressure non-linear increasing rule _fWith Δ p _r, again according to formula p _If=p _f+ Δ p _fAnd p _Ir=p _r+ Δ p _r, calculate the line pressure p of the long Δ t of this time step front axle brake device and rear brake when finishing _IfAnd p _Ir, and with p _IfAnd p _IrUnloading is p respectively _fAnd p _r, so that the line pressure parameter in the storage unit is carried out real-time update;

20322, again according to the p that calculates in the step 20321 _fAnd p _r, calculate the output torque M of front axle brake device and rear brake _BfAnd M _Br, and the output torque parameter in the storage unit carried out real-time update;

20323, the engine brake force F described in the integrating step 202 _eAnd the vertical ground of automobile front and rear wheel directed force F _FbAnd F _Rb, and according to formula ∑ M _Wf=M _Bf-F _FbR=I _Wfε _WfWith

Calculate the angular deceleration ε of tested diaxon automobile front and back wheel _WfAnd ε _Wr, and the angular deceleration parameter in the storage unit carried out real-time update;

20324, call angular speed calculation module and according to formula ω _If=ω _f-ε _Wf* Δ t and ω _Ir=ω _r-ε _Wr* Δ t calculates the angular velocity omega of the long Δ t of this time step front axle brake device or rear brake when finishing _IfAnd ω _Ir, and unloading is ω _fAnd ω _rSo that the angular velocity parameter in the storage unit is carried out real-time update;

20325, according to formula ∑ F _X=-2 (F _Fb+ F _Rb)-F _e=-Ma _X, calculate the retarded velocity a of the long Δ t of this time step tested diaxon automobile when finishing _IXAnd unloading is a _XAgain according to formula V _I0=V ₀-a _XΔ t calculates the vehicle velocity V of the long Δ t of this time step tested diaxon automobile when finishing _I0And unloading is V ₀, so that the speed of a motor vehicle parameter in the storage unit is carried out real-time update;

20326, in conjunction with ω _f, ω _rAnd V ₀, and according to formula

With

Calculate the slip rate s of front-wheel and trailing wheel _IfAnd s _If, and unloading is s respectively _fAnd s _r, so that the slip rate parameter in the storage unit is carried out real-time update;

20327, according to tire model and in conjunction with s _fAnd s _rCalculate the long Δ t of this time step vertical ground of automobile front and rear wheel directed force F when finishing _FbAnd F _RbAnd deposit in the storage unit synchronously, and the kinetic model of tackling in the step 202 mutually to be set up carries out real-time update;

20328, according to vehicle velocity V ₀And in conjunction with the engine brake force F that draws through conventional experimental test _eWith vehicle velocity V ₀Between funtcional relationship, calculate the long Δ t of this time step engine brake force F when finishing _eAnd deposit in the storage unit synchronously, and the kinetic model of tackling in the step 202 mutually to be set up carries out real-time update;

20329, judge | a _XWhether-3| less than δ, δ in the formula=0.01～0.001: when | a _XDuring-3|＜δ, with the p that calculates in the step 20321 _fAnd p _rOutput also saves as p _MfAnd p _Mr, and with p _MfAnd p _MrThe line pressure value of front axle and rear brake when continuing braking in the braking heat fading cyclic process; Otherwise, return step 20321.

Particularly: according to brake structural parameter and coefficientoffriction, can try to achieve the usefulness factor BF of detent: the detent of different types, computing formula are also different.For common typical spot-type disc brake, braking efficiency factor BF is:

BF=2 μ, μ in the formula---the friction factor between dish and Brake pad.

The fixing neck of fulcrum is from shoe drum brake, the neck hoof, is respectively from the usefulness factor BF of hoof

${\mathrm{BF}}_1=\frac{\mathrm{\ζ}}{\frac{\mathrm{\κ}\cos \mathrm{\λ}}{\mathrm{\ρ}\cos \mathrm{\β}\sin \mathrm{\γ}}-1};$

${\mathrm{BF}}_2=\frac{\mathrm{\ζ}}{\frac{\mathrm{\κ}\cos {\mathrm{\λ}}^{\′}}{\mathrm{\ρ}\cos \mathrm{\β}\sin \mathrm{\γ}}+1};$

If two hoof open power F ₁, F ₂Identical, then its braking efficiency factor BF is

BF＝BF ₁+BF ₂

α---maximum pressure line and cornerite bisector angle;

l ₀---the Center of Pressure circular diameter, $l_0=\frac{4\sin \mathrm{\θ}/2}{\mathrm{\θ}+\sin \mathrm{\θ}}R;$

γ---angle of friction, γ=arctan μ, μ are the friction pair friction factor;

$\mathrm{\ζ}=\frac{a+e}{R};$ $\mathrm{\κ}=\frac{f}{R};$ $\mathrm{\ρ}=\frac{l_0}{R};$ λ＝γ+β-α；λ′＝γ-β+α； $\mathrm{\α}=\frac{\mathrm{\π}}{2}-\frac{\mathrm{\θ}}{2}-{\mathrm{\θ}}_1;$

$\mathrm{\β}=\arctan \left(\frac{\mathrm{\θ}-\sin \mathrm{\θ}}{\mathrm{\θ}+\sin \mathrm{\θ}}\tan \mathrm{\α}\right).$

The computation process of brake-pipe pressure p is as follows: for Pneumatic braking system, can utilize brake output torque expression formula M _b=(p-p ₀) A _cη _mBF ρ r ' (is line pressure p, by M _b, relational expression between BF and p) calculate, in the formula:

P, p ₀---consumption is pressed in line pressure, release;

ρ, A _c, η _m, r ', BF---radius of action, the braking efficiency factor of brake chamber to brake level ratio, brake chamber area, brake chamber to detent driving mechanism mechanical efficiency, brake drum or brake disc;

For brake fluid system, according to line pressure p, by M _b, relational expression between BF and p, promptly its brake output torque is:

M _b=(p-p ₀) A _Wcη _aBFr ' (this formula is the funtcional relationship between brake output torque and the line pressure)

In the formula

A _Wc, η _a---mechanical efficiency after the master cylinder in wheel cylinder working area, the braking drive organ, r ' is the brake drum of brake to be tested or the radius of action of brake disc.

204, cyclic brake: the kinetic model of the diaxon automobile of being set up in parameter that sets according to step 201 and the step 202, in the maximum pipeline pressure p that keeps front axle brake device and rear brake _f=p _MfAnd p _r=p _MrPrerequisite under, divide m time respectively to the braking heat fading process of described front axle brake device and the rear brake virtual test that circulates, the test process of its circulation virtual test is as follows:

2041, call the loop test module and carry out the test in first time step Δ t in the brake head fade test process, its process of the test is as follows:

20411, according to step 20311 to step 20318, calculate the angular velocity omega of the long Δ t of this time step front axle brake device and rear brake when finishing respectively _IfAnd ω _Ir, the vertical ground of automobile front and rear wheel directed force F _FbAnd F _RbAnd engine brake force F _e, and with the angular velocity omega of front axle brake device and rear brake _IfAnd ω _IrUnloading is ω respectively _fAnd ω _rAfter, the kinetic model of tackling in the step 202 mutually to be set up carries out real-time update;

20412, the detent temperature rise is calculated, and calls detent temperature rise computing module the transient behavior temperature T (t) of front axle brake device and rear brake in the long Δ t of this time step is calculated respectively, and its computation process is as follows:

20412a, according to formula p _Bf=M _Bfω _f, calculate front axle brake device and and the absorption braking power p of rear brake in the long Δ t of this time step _BfAnd p _Br, and the front axle brake device that will be tried to achieve this moment and the absorption braking power p of rear brake _BfAnd p _BrDeposit in synchronously in the described storage unit, the absorption braking power parameter in the described storage unit is carried out real-time update;

20412b, according to temperature variation differential equation P _Bf* dt-h * A[T (t)-T _E] dt=m * c * dT (t) and P _Br* dt-h * A[T (t)-T _E] dt=m * c * dT (t), solve the transient behavior temperature T (t) of interior front axle brake device of the long Δ t of this time step and rear brake respectively, and will this moment the front axle brake device that be tried to achieve and the transient behavior temperature T (t) of rear brake deposit in synchronously in the described storage unit, the transient behavior temperature parameter of front axle brake device in the described storage unit and rear brake is carried out real-time update; In the formula, h is the convection transfer rate of front axle brake device or rear brake, and m is the quality of the rotary part of front axle brake device or rear brake, and c is the specific heat of the material that rotary part adopts of front axle brake device or rear brake, T _EBe environment temperature;

20413, heat fading frictional behaviour is calculated: call heat fading frictional behaviour computing unit, according to the front axle brake device that calculates and the transient behavior temperature T (t) of rear brake among the funtcional relationship μ=f (T) of checking in the step 103 and the integrating step 20412b, corresponding calculate respectively front axle brake device and rear brake at this moment between hot coefficientoffriction in the step delta t _fAnd μ _rAnd corresponding depositing in the storage unit;

20414, call described parameter calculation unit, and according to the hot coefficientoffriction that calculates in the conventional computing method of braking efficiency factor and the integrating step 20413 _fAnd μ _r, calculate the usefulness factor BF of front axle brake device and rear brake in the long Δ t of this time step _fAnd BF _rAgain according to the conventional computing method of brake output torque, and in conjunction with the usefulness factor BF that is calculated this moment _fAnd BF _rWith front axle brake organ pipe road pressure p _fWith rear brake line pressure p _r, when corresponding reckoning draws the long Δ t of this time step and finishes, the output torque M of front axle brake device and rear brake _BfAnd M _Br, and with the usefulness factor BF that is calculated _fAnd BF _rAnd output torque M _BfAnd M _BrDeposit in synchronously in the described storage unit, braking efficiency factor in the described storage unit and output torque parameter are carried out real-time update; The diaxon automobile dynamics model of simultaneously, tackling in the step 203 mutually to be set up carries out real-time update;

20415, utilize the diaxon automobile dynamics model after the real-time update in the step 20414, and according to formula ∑ M _Wf=M _Bf-F _FbR=I _Wfε _Wf, the call parameters computing module calculates the front-wheel angular acceleration ε of the long Δ t of this time step when finishing _WfWith trailing wheel angular acceleration ε _Wr, and the front-wheel angular acceleration ε that will be calculated this moment _WfWith trailing wheel angular acceleration ε _WrDeposit in synchronously in the described storage unit, the front-wheel angular acceleration parameter in the described storage unit is carried out real-time update;

2042, call the loop test module and brake the test in next time step Δ t in the test process, its test process is as follows:

20421, according to step 20321 to step 20328, calculate the angular velocity omega of the long Δ t of this time step front axle brake device and rear brake when finishing respectively _IfAnd ω _Ir, the vertical ground of automobile front and rear wheel directed force F _FbAnd F _RbAnd engine brake force F _e, and with the angular velocity omega of front axle brake device and rear brake _IfAnd ω _IrUnloading is ω _fAnd ω _r, and the kinetic model of tackling in the step 202 mutually to be set up carries out real-time update;

20422, the detent temperature rise is calculated, and calls detent temperature rise computing module the transient behavior temperature T (t) of front axle brake device and rear brake in the long Δ t of this time step is calculated respectively, and its computation process is as follows:

20422a, according to formula p _Bf=M _Bfω _f, calculate front axle brake device and and the absorption braking power p of rear brake in the long Δ t of this time step _BfAnd p _Br, and the front axle brake device that will be tried to achieve this moment and the absorption braking power p of rear brake _BfAnd p _BrDeposit in synchronously in the described storage unit, the absorption braking power parameter in the described storage unit is carried out real-time update;

20422b, according to temperature variation differential equation P _Bf* dt-h * A[T (t)-T _E] dt=m * c * dT (t) and P _Br* dt-h * A[T (t)-T _E] dt=m * c * dT (t), solve the transient behavior temperature T (t) of interior front axle brake device of the long Δ t of this time step and rear brake respectively, and will this moment the front axle brake device that be tried to achieve and the transient behavior temperature T (t) of rear brake deposit in synchronously in the described storage unit, the transient behavior temperature parameter of front axle brake device in the described storage unit and rear brake is carried out real-time update; In the formula, h is the convection transfer rate of front axle brake device or rear brake, and m is the quality of the rotary part of front axle brake device or rear brake, and c is the specific heat of the material that rotary part adopts of front axle brake device or rear brake, T _EBe environment temperature;

20423, heat fading frictional behaviour is calculated: call heat fading frictional behaviour computing unit, according to the front axle brake device that calculates and the transient behavior temperature T (t) of rear brake among the funtcional relationship μ=f (T) of checking in the step 103 and the integrating step 20412b, corresponding calculate respectively front axle brake device and rear brake at this moment between hot coefficientoffriction in the step delta t _fAnd μ _rAnd corresponding depositing in the storage unit;

20424, call described parameter calculation unit, and according to the hot coefficientoffriction that calculates in the conventional computing method of braking efficiency factor and the integrating step 20423 _fAnd μ _r, calculate the usefulness factor BF of front axle brake device and rear brake in the long Δ t of this time step _fAnd BF _rAgain according to the conventional computing method of brake output torque, and in conjunction with the usefulness factor BF that is calculated this moment _fAnd BF _rWith front axle brake organ pipe road pressure p _fWith rear brake line pressure p _r, when corresponding reckoning draws the long Δ t of this time step and finishes, the output torque M of front axle brake device and rear brake _BfAnd M _Br, and with the usefulness factor BF that is calculated _fAnd BF _rAnd output torque M _BfAnd M _BrDeposit in synchronously in the described storage unit, braking efficiency factor in the described storage unit and output torque parameter are carried out real-time update; The diaxon automobile dynamics model of simultaneously, tackling in the step 203 mutually to be set up carries out real-time update;

20425, utilize the diaxon automobile dynamics model after the real-time update in the step 20424, and according to formula ∑ M _Wf=M _Bf-F _FbR=I _Wfε _Wf, the call parameters computing module calculates the front-wheel angular acceleration ε of the long Δ t of this time step when finishing _WfWith trailing wheel angular acceleration ε _Wr, and the front-wheel angular acceleration ε that will be calculated this moment _WfWith trailing wheel angular acceleration ε _WrDeposit in synchronously in the described storage unit, front-wheel angular acceleration parameter in the described storage unit and trailing wheel angular acceleration parameter are carried out real-time update;

When 20426, this time step Δ t finishes, to the vehicle velocity V of the tested diaxon automobile after upgrading in the current described storage unit ₀Judge: when

The time, return step 2042, proceed the experimental test in next the time step Δ t in the brake test process, so constantly circulation; When

The time, the brake test process of finishing in this fade test's virtual test process is described, then enter step 2043, the used time step number of brake test process is n among this fade test at this moment ₁

2043, the brake temperature in detent speed-raising heat radiation stage calculates, and its computation process is as follows:

20431, call the calculating in first time step Δ t in the speed-raising heat radiation computation process that circulates of detent speed-raising radiating module, its computation process is as follows:

20431a, according to formula-h * A[T (t)-T _E] dt=m * c * dT (t), the transient behavior temperature T (t) that solves interior front axle brake device of the long Δ t of this time step and rear brake also deposits in the described storage unit synchronously, and the temperature parameter in the described storage unit is carried out real-time update, T in the formula _EBe environment temperature, h is the convection transfer rate of front axle brake device or rear brake, m _BfBe the quality of the rotary part of front axle brake device or rear brake, c is the specific heat of the material that rotary part adopts of front axle brake device or rear brake;

20431b, speed-raising heat radiation frictional behaviour are calculated: according to the front axle brake device that calculates among the funtcional relationship μ=f (T) of checking in the step 103 and the integrating step 20431a and the transient behavior temperature T (t) of rear brake, calculate front axle brake device and rear brake at this moment between hot coefficientoffriction in the step delta t _fAnd μ _r, and corresponding depositing in the storage unit;

20432, call the calculating in the next time step Δ t in the speed-raising heat radiation computation process that circulates of detent speed-raising radiating module, its computation process is as follows:

20432a, according to formula-h * A[T (t)-T _E] dt=m * c * dT (t), the transient behavior temperature T (t) that solves interior front axle brake device of the long Δ t of this time step and rear brake also deposits in the described storage unit synchronously, and the temperature parameter in the described storage unit is carried out real-time update;

20432b, speed-raising heat radiation frictional behaviour are calculated: according to the front axle brake device that calculates among the funtcional relationship μ=f (T) of checking in the step 103 and the integrating step 20432a and the transient behavior temperature T (t) of rear brake, calculate front axle brake device and rear brake at this moment between hot coefficientoffriction in the step delta t _fAnd μ _r, and corresponding depositing in the storage unit;

20433, return step 20432, the calculating of next time step Δ t in the speed-raising heat radiation computation process of proceeding to circulate constantly repeats and through m ₁=(t-n ₁* Δ t)/Δ t time step enters step 20434 after calculating, and the used time step number of speed-raising heat radiation computation process is m among this fade test ₁

2044, repeating step 2041 until finishing heat fading performance circulation virtual test m time, is then finished the temperature rise and the frictional behaviour virtual test process of described tested diaxon automobile front axle detent and rear brake to step 2043;

Step 2 is carried out in the virtual test process, export all computational datas of being stored in the described storage unit by the display that joins with described arithmetic processor and show synchronously, this moment, the temperature rise and the frictional behaviour virtual test process of tested each shaft brake of diaxon automobile finished.

In the present embodiment, after finishing the temperature rise and frictional behaviour virtual test process of described tested diaxon automobile front axle detent in the step 2044, also need utilize arithmetic processor and according to I type braking ability fade test method tested diaxon automobile is repeated to brake after the heat fading brake efficiency carry out virtual test, its test process may further comprise the steps:

301, initial parameter is set and storage: the heat fading brake efficiency after according to I type braking ability fade test method tested diaxon automobile being repeated to brake carries out the operating condition of test of virtual test, determine tested diaxon automobile is carried out the test parameters of virtual test, comprise the initial velocity V of brake to be tested vehicle of living in ₂And deposit in the storage unit synchronously;

302, the diaxon automobile dynamics model that utilizes in the step 202 to be set up, calculating at initial velocity is V ₂And the automobile brake distance and the braking deceleration of described diaxon automobile that is to say under the state that stops in emergency, and need in this step the kinetic parameter of described diaxon automobile dynamics model is made amendment;

Carry out in the step 302 in the virtual test process, export all computational datas of being stored in the described storage unit by the display that joins with described arithmetic processor, tide of motorism decline brake efficiency test process finishes.

The above; it only is preferred embodiment of the present invention; be not that the present invention is imposed any restrictions, everyly any simple modification that above embodiment did, change and equivalent structure changed, all still belong in the protection domain of technical solution of the present invention according to the technology of the present invention essence.

Claims (4)

1. diaxon running braking system I type braking ability heat fading virtual test method is characterized in that this method may further comprise the steps:

Step 1, determine the funtcional relationship μ=f (T) between the friction factor-temperature of tested diaxon automotive brake brake friction pair, brake to be tested is drum brake or disc brake, and its deterministic process is as follows:

101, set up 3-D geometric model:, utilize CAD software to set up the 3-D geometric model of brake to be tested according to the assembly structure of brake to be tested;

102, set up three-dimensional heat-machine coupling finite element model, its modeling process is as follows:

1021,3-D geometric model described in the step 1 is imported in many coupling analysis softwares;

1022, under many coupling analysis software environments, select analytic unit and with selected analytic unit described 3-D geometric model is carried out grid dividing, selected analytic unit comprises 3D solid structural unit, rubbing contact unit and three types of unit of convection current radiating element of brake to be tested;

1023, that input is inquired according to the construction material handbook or the material property parameter by the measured brake to be tested of conventional material performance test test, select a kind of convergence rubbing contact algorithm fast, selected simultaneously friction factor-temperature model, finally set up three-dimensional heat-machine coupling finite element model, described friction factor-temperature model is the funtcional relationship μ=f (T) between the friction factor-temperature of brake to be tested brake friction pair, μ is the friction factor of brake to be tested brake friction pair in the formula, and T is the rubbing contact surface temperature of brake to be tested brake friction pair; Described material property parameter comprises elastic modulus, density, coefficient of heat conductivity, specific heat capacity, thermal expansivity and the Poisson ratio of brake to be tested material that brake friction pair adopts;

103, to the Temperature Field Simulation analysis that is coupled of the three-dimensional heat set up-machine coupling finite element model, selected one or more test points on the brake to be tested brake friction pair, to compare in Temperature Field Simulation result on each test point and the temperature test result who adopts conventional brake device temperature-raising experimental method to be tested on to each test point described three-dimensional heat-machine coupling finite element model, thereby the μ=f of funtcional relationship described in the step 3 (T) is verified, realization is carried out accurate identification to the coefficient among funtcional relationship μ=f (T), finally draws the funtcional relationship μ=f (T) between the friction factor-temperature of brake to be tested brake friction pair;

Step 2, utilize arithmetic processor and according to I type braking ability fade test method the temperature rise and the frictional behaviour of tested each shaft brake of diaxon automobile are carried out virtual test, its test process may further comprise the steps:

201, initial parameter is set, is calculated and storage: according to the operating condition of test that repeats to brake of automobile I type braking ability fade test method regulation, determine brake to be tested is carried out the test parameters of virtual test, comprise the initial velocity V of brake to be tested vehicle of living in ₀And this moment V ₀=constant v, automobile brake retarded velocity a ₀, brake to be tested initial temperature T ₀, cyclic brake number of times and braking period, and global cycle number of times m and cycle period t are set according to determined cyclic brake number of times and braking period; Afterwards, call parameters is provided with the structural parameters that described test parameters and automobile and detent are imported in the unit, simultaneously according to measuring accuracy and efficiency requirements setting-up time step delta t, and calculate the time total step number k=t/ Δ t of cyclic brake process each time, and with the V that is imported ₀, a ₀, m, t, Δ t, k, ω ₀And T ₀All deposit in the storage unit synchronously; Call parameters computing unit and simultaneously according to formula

Calculate the initial angular velocity omegae of rotary part in the brake to be tested ₀, and with initial angular velocity omegae ₀Unloading is ω respectively _fAnd ω _rAfter deposit in the storage unit synchronously; Brake to be tested vehicle of living in is the diaxon automobile, and then described brake to be tested comprises front axle brake device that the front-wheel of diaxon automobile is braked and the rear brake that the trailing wheel of diaxon automobile is braked; Described rotary part is the brake drum of described drum brake or the brake disc of disc brake;

202, modeling: described arithmetic processor is learned system of equations according to automobile five degree of freedom brake power:

Set up the kinetic model of brake to be tested diaxon automobile of living in, the front-wheel of described diaxon automobile is identical with the radius of trailing wheel, ∑ F in the formula _X, ∑ F _Z, ∑ M _Y, ∑ M _WfWith ∑ M _WrBe respectively that automobile longitudinal is made a concerted effort, sprung mass is vertically made a concerted effort, sprung mass pitching resultant moment, front-wheel resultant moment and trailing wheel resultant moment; F _FbAnd F _RbBe the vertical ground force of calculating according to tire model, slip rate and wheel weight of automobile front and rear wheel; F _e, F _Fk, F _Fd, F _Rk, F _Rd, M _BfAnd M _BrBe respectively engine brake force, front suspension flexible member acting force, front suspension damping element acting force, rear suspension flexible member acting force, rear suspension damping element acting force, front axle brake device output torque and rear brake output torque, and above-mentioned variable is setting in advance on the basis of initial value and learns system of equations according to brake power and dynamically resolve; M, M _s, I _s, I _WfAnd I _WrBe respectively car mass, sprung mass, sprung mass is around barycenter moment of inertia, front-wheel moment of inertia and trailing wheel moment of inertia and set in step 201; A, b and r be respectively the automobile barycenter to front axle distance, barycenter is to the rolling radius of rear axle distance and wheel and set in step 201; a _X, a _SZ, ε _SY, ε _WfAnd ε _WrBe respectively automobile longitudinal acceleration, sprung mass vertical acceleration, sprung mass angle of pitch acceleration, front-wheel angular acceleration and trailing wheel angular acceleration, and above-mentioned variable resolves dynamically according to brake power system of equations;

When setting up described diaxon automobile dynamics model, with above-mentioned parameter respectively correspondence deposit in the storage unit and this moment in

The line pressure value of detent determines that its deterministic process is as follows when 203, continuing braking in the tested diaxon automobile brake heat fading cyclic process:

2031, call line pressure value determination module and carry out the definite of first time step Δ t inner brake line pressure value, its deterministic process is as follows:

20311, determine the line pressure incremental change Δ p of front axle brake device and rear brake earlier according to line pressure non-linear increasing rule _fWith Δ p _r, again according to formula p _If=p _0f+ Δ p _fAnd p _Ir=p _0r+ Δ p _r, calculate the line pressure p of the long Δ t of this time step front axle brake device and rear brake when finishing _IfAnd p _Ir, and with p _IfAnd p _IrUnloading is p respectively _fAnd p _r, the line pressure parameter in the storage unit is carried out real-time update, wherein p _0fAnd p _0rFor consumption is pressed in the release of tested diaxon automobile front axle detent and rear brake;

20312, according to the p that calculates in the step 20311 _fAnd p _r, calculate the output torque M of front axle brake device and rear brake _BfAnd M _Br, and the output torque parameter in the storage unit carried out real-time update;

20313, the engine brake force F described in the integrating step 202 _eAnd the vertical ground of automobile front and rear wheel directed force F _FbAnd F _Rb, and according to formula ∑ M _Wf=M _Bf-F _FbR=I _Wfε _WfWith

Calculate the angular deceleration ε of tested diaxon automobile front and back wheel _WfAnd ε _Wr, and the angular deceleration parameter in the storage unit carried out real-time update;

20314, call angular speed calculation module and according to formula ω _If=ω _f-ε _Wf* Δ t and ω _Ir=ω _r-ε _Wr* Δ t calculates the angular velocity omega of the long Δ t of this time step front axle brake device or rear brake when finishing _IfAnd ω _Ir, and unloading is ω _fAnd ω _rSo that the angular velocity parameter in the storage unit is carried out real-time update;

20315, according to formula ∑ F _X=-2 (F _Fb+ F _Rb)-F _e=-Ma _X, calculate the retarded velocity a of the long Δ t of this time step tested diaxon automobile when finishing _IXAnd unloading is a _XAgain according to formula V _I0=V ₀-a _XΔ t calculates the vehicle velocity V of the long Δ t of this time step tested diaxon automobile when finishing _I0And unloading is V ₀, so that the speed of a motor vehicle parameter in the storage unit is carried out real-time update;

20316, in conjunction with ω _f, ω _rAnd V ₀, and according to formula With

Calculate the slip rate s of front-wheel and trailing wheel _IfAnd s _Ir, and unloading is s respectively _fAnd s _rSo that the slip rate parameter in the storage unit is carried out real-time update;

20317, according to tire model and in conjunction with s _fAnd s _r, calculate the long Δ t of this time step vertical ground of automobile front and rear wheel directed force F when finishing _FbAnd F _RbAnd deposit in the storage unit synchronously, and the kinetic model of tackling in the step 202 mutually to be set up carries out real-time update;

20318, according to vehicle velocity V ₀And in conjunction with the engine brake force F that draws through conventional experimental test _eWith vehicle velocity V ₀Between funtcional relationship, calculate the long Δ t of this time step engine brake force F when finishing _eAnd deposit in the storage unit synchronously, and the kinetic model of tackling in the step 202 mutually to be set up carries out real-time update;

20319, judge | a _XWhether-3| less than δ, wherein δ=0.01～0.001: when | a _XDuring-3|＜δ, with the p that calculates in the step 20311 _fAnd p _rOutput also saves as p _MfAnd p _Mr, and with p _MfAnd p _MrThe line pressure value of front axle and rear brake when continuing braking in the braking heat fading cyclic process; Otherwise, enter step 2032;

2032, call line pressure value determination module and carry out the definite of next time step Δ t inner brake line pressure value, its deterministic process is as follows:

20321, determine the line pressure incremental change Δ p of front axle brake device and rear brake earlier according to line pressure non-linear increasing rule _fWith Δ p _r, again according to formula p _If=p _f+ Δ p _fAnd p _Ir=p _r+ Δ p _r, calculate the line pressure p of the long Δ t of this time step front axle brake device and rear brake when finishing _IfAnd p _Ir, and with p _IfAnd p _IrUnloading is p respectively _fAnd p _r, so that the line pressure parameter in the storage unit is carried out real-time update;

20322, again according to the p that calculates in the step 20321 _fAnd p _r, calculate the output torque M of front axle brake device and rear brake _BfAnd M _Br, and the output torque parameter in the storage unit carried out real-time update;

20323, the engine brake force F described in the integrating step 202 _eAnd the vertical ground of automobile front and rear wheel directed force F _FbAnd F _Rb, and according to formula ∑ M _Wf=M _Bf-F _FbR=I _Wfε _WfWith

Calculate the angular deceleration ε of tested diaxon automobile front and back wheel _WfAnd ε _Wr, and the angular deceleration parameter in the storage unit carried out real-time update;

20324, call angular speed calculation module and according to formula ω _If=ω _f-ε _Wf* Δ t and ω _Ir=ω _r-ε _Wr* Δ t calculates the angular velocity omega of the long Δ t of this time step front axle brake device or rear brake when finishing _IfAnd ω _Ir, and unloading is ω _fAnd ω _rSo that the angular velocity parameter in the storage unit is carried out real-time update;

20325, according to formula ∑ F _X=-2 (F _Fb+ F _Rb)-F _e=-Ma _X, calculate the retarded velocity a of the long Δ t of this time step tested diaxon automobile when finishing _IXAnd unloading is a _XAgain according to formula V _I0=V ₀-a _XΔ t calculates the vehicle velocity V of the long Δ t of this time step tested diaxon automobile when finishing _I0And unloading is V ₀, so that the speed of a motor vehicle parameter in the storage unit is carried out real-time update;

20326, in conjunction with ω _f, ω _rAnd V ₀, and according to formula

With

Calculate the slip rate s of front-wheel and trailing wheel _IfAnd s _Ir, and unloading is s respectively _fAnd s _r, so that the slip rate parameter in the storage unit is carried out real-time update;

20327, according to tire model and in conjunction with s _fAnd s _rCalculate the long Δ t of this time step vertical ground of automobile front and rear wheel directed force F when finishing _FbAnd F _RbAnd deposit in the storage unit synchronously, and the kinetic model of tackling in the step 202 mutually to be set up carries out real-time update;

20328, according to vehicle velocity V ₀And in conjunction with the engine brake force F that draws through conventional experimental test _eWith vehicle velocity V ₀Between funtcional relationship, calculate the long Δ t of this time step engine brake force F when finishing _eAnd deposit in the storage unit synchronously, and the kinetic model of tackling in the step 202 mutually to be set up carries out real-time update;

20329, judge | a _XWhether-3| less than δ, δ in the formula=0.01～0.001: when | a _XDuring-3|＜δ, with the p that calculates in the step 20321 _fAnd p _rOutput also saves as p _MfAnd p _Mr, and with p _MfAnd p _MrThe line pressure value of front axle and rear brake when continuing braking in the braking heat fading cyclic process; Otherwise, return step 20321;

204, cyclic brake: the kinetic model of the diaxon automobile of being set up in parameter that sets according to step 201 and the step 202, in the maximum pipeline pressure p that keeps front axle brake device and rear brake _f=p _MfAnd p _r=p _MrPrerequisite under, divide m time respectively to the braking heat fading process of described front axle brake device and the rear brake virtual test that circulates, the test process of its circulation virtual test is as follows:

2041, call the loop test module and carry out the test in first time step Δ t in the brake head fade test process, its process of the test is as follows:

20411, according to step 20311 to step 20318, calculate the angular velocity omega of the long Δ t of this time step front axle brake device and rear brake when finishing respectively _IfAnd ω _Ir, the vertical ground of automobile front and rear wheel directed force F _FbAnd F _RbAnd engine brake force F _e, and with the angular velocity omega of front axle brake device and rear brake _IfAnd ω _IrUnloading is ω respectively _fAnd ω _rAfter, the kinetic model of tackling in the step 202 mutually to be set up carries out real-time update;

20412, the detent temperature rise is calculated, and calls detent temperature rise computing module the transient behavior temperature T (t) of front axle brake device and rear brake in the long Δ t of this time step is calculated respectively, and its computation process is as follows:

20412a, according to formula p _Bf=M _Bfω _f, calculate front axle brake device and and the absorption braking power p of rear brake in the long Δ t of this time step _BfAnd p _Br, and the front axle brake device that will be tried to achieve this moment and the absorption braking power p of rear brake _BfAnd p _BrDeposit in synchronously in the described storage unit, the absorption braking power parameter in the described storage unit is carried out real-time update;

20412b, according to temperature variation differential equation P _Bf* dt-h * A[T (t)-T _E] dt=m * c * dT (t) and P _Br* dt-h * A[T (t)-T _E] dt=m * c * dT (t), solve the transient behavior temperature T (t) of interior front axle brake device of the long Δ t of this time step and rear brake respectively, and will this moment the front axle brake device that be tried to achieve and the transient behavior temperature T (t) of rear brake deposit in synchronously in the described storage unit, the transient behavior temperature parameter of front axle brake device in the described storage unit and rear brake is carried out real-time update; In the formula, h is the convection transfer rate of front axle brake device or rear brake, and m is the quality of the rotary part of front axle brake device or rear brake, and c is the specific heat of the material that rotary part adopts of front axle brake device or rear brake, T _EBe environment temperature;

20413, heat fading frictional behaviour is calculated: call heat fading frictional behaviour computing unit, according to the front axle brake device that calculates and the transient behavior temperature T (t) of rear brake among the funtcional relationship μ=f (T) of checking in the step 103 and the integrating step 20412b, corresponding calculate respectively front axle brake device and rear brake at this moment between hot coefficientoffriction in the step delta t _fAnd μ _rAnd corresponding depositing in the storage unit;

20414, call described parameter calculation unit, and according to the hot coefficientoffriction that calculates in the conventional computing method of braking efficiency factor and the integrating step 20413 _fAnd μ _r, calculate the usefulness factor BF of front axle brake device and rear brake in the long Δ t of this time step _fAnd BF _rAgain according to the conventional computing method of brake output torque, and in conjunction with the usefulness factor BF that is calculated this moment _fAnd BF _rWith front axle brake organ pipe road pressure p _fWith rear brake line pressure p _r, when corresponding reckoning draws the long Δ t of this time step and finishes, the output torque M of front axle brake device and rear brake _BfAnd M _Br, and with the usefulness factor BF that is calculated _fAnd BF _rAnd output torque M _BfAnd M _BrDeposit in synchronously in the described storage unit, braking efficiency factor in the described storage unit and output torque parameter are carried out real-time update; The diaxon automobile dynamics model of simultaneously, tackling in the step 203 mutually to be set up carries out real-time update;

20415, utilize the diaxon automobile dynamics model after the real-time update in the step 20414, and according to formula ∑ M _Wf=M _Bf-F _FbR=I _Wfε _Wf, the call parameters computing module calculates the front-wheel angular acceleration ε of the long Δ t of this time step when finishing _WfWith trailing wheel angular acceleration ε _Wr, and the front-wheel angular acceleration ε that will be calculated this moment _WfWith trailing wheel angular acceleration ε _WrDeposit in synchronously in the described storage unit, front-wheel angular acceleration parameter in the described storage unit and trailing wheel angular acceleration parameter are carried out real-time update;

2042, call the loop test module and brake the test in next time step Δ t in the test process, its test process is as follows:

20421, according to step 20321 to step 20328, calculate the angular velocity omega of the long Δ t of this time step front axle brake device and rear brake when finishing respectively _IfAnd ω _Ir, the vertical ground of automobile front and rear wheel directed force F _FbAnd F _RbAnd engine brake force F _e, and with the angular velocity omega of front axle brake device and rear brake _IfAnd ω _IrUnloading is ω _fAnd ω _r, and the kinetic model of tackling in the step 202 mutually to be set up carries out real-time update;

20422, the detent temperature rise is calculated, and calls detent temperature rise computing module the transient behavior temperature T (t) of front axle brake device and rear brake in the long Δ t of this time step is calculated respectively, and its computation process is as follows:

20422a, according to formula p _Bf=M _Bfω _f, calculate front axle brake device and and the absorption braking power p of rear brake in the long Δ t of this time step _BfAnd p _Br, and the front axle brake device that will be tried to achieve this moment and the absorption braking power p of rear brake _BfAnd p _BrDeposit in synchronously in the described storage unit, the absorption braking power parameter in the described storage unit is carried out real-time update;

20422b, according to temperature variation differential equation P _Bf* dt-h * A[T (t)-T _E] dt=m * c * dT (t) and P _Br* dt-h * A[T (t)-T _E] dt=m * c * dT (t), solve the transient behavior temperature T (t) of interior front axle brake device of the long Δ t of this time step and rear brake respectively, and will this moment the front axle brake device that be tried to achieve and the transient behavior temperature T (t) of rear brake deposit in synchronously in the described storage unit, the transient behavior temperature parameter of front axle brake device in the described storage unit and rear brake is carried out real-time update; In the formula, h is the convection transfer rate of front axle brake device or rear brake, and m is the quality of the rotary part of front axle brake device or rear brake, and c is the specific heat of the material that rotary part adopts of front axle brake device or rear brake, T _EBe environment temperature;

20423, heat fading frictional behaviour is calculated: call heat fading frictional behaviour computing unit, according to the front axle brake device that calculates and the transient behavior temperature T (t) of rear brake among the funtcional relationship μ=f (T) of checking in the step 103 and the integrating step 20412b, corresponding calculate respectively front axle brake device and rear brake at this moment between hot coefficientoffriction in the step delta t _fAnd μ _rAnd corresponding depositing in the storage unit;

20424, call described parameter calculation unit, and according to the hot coefficientoffriction that calculates in the conventional computing method of braking efficiency factor and the integrating step 20423 _fAnd μ _r, calculate the usefulness factor BF of front axle brake device and rear brake in the long Δ t of this time step _fAnd BF _rAgain according to the conventional computing method of brake output torque, and in conjunction with the usefulness factor BF that is calculated this moment _fAnd BF _rWith front axle brake organ pipe road pressure p _fWith rear brake line pressure p _r, when corresponding reckoning draws the long Δ t of this time step and finishes, the output torque M of front axle brake device and rear brake _BfAnd M _Br, and with the usefulness factor BF that is calculated _fAnd BF _rAnd output torque M _BfAnd M _BrDeposit in synchronously in the described storage unit, braking efficiency factor in the described storage unit and output torque parameter are carried out real-time update; The diaxon automobile dynamics model of simultaneously, tackling in the step 203 mutually to be set up carries out real-time update;

20425, utilize the diaxon automobile dynamics model after the real-time update in the step 20424, and according to formula ∑ M _Wf=M _Bf-F _FbR=I _Wfε _Wf, the call parameters computing module calculates the front-wheel angular acceleration ε of the long Δ t of this time step when finishing _WfWith trailing wheel angular acceleration ε _Wr, and the front-wheel angular acceleration ε that will be calculated this moment _WfWith trailing wheel angular acceleration ε _WrDeposit in synchronously in the described storage unit, the front-wheel angular acceleration parameter in the described storage unit is carried out real-time update;

When 20426, this time step Δ t finishes, to the vehicle velocity V of the tested diaxon automobile after upgrading in the current described storage unit ₀Judge: when The time, return step 2042, proceed the experimental test in next the time step Δ t in the brake test process, so constantly circulation; When

The time, the brake test process of finishing in this fade test's virtual test process is described, then enter step 2043, the used time step number of brake test process is n among this fade test at this moment ₁

2043, the brake temperature in detent speed-raising heat radiation stage calculates, and its computation process is as follows:

20431, call the calculating in first time step Δ t in the speed-raising heat radiation computation process that circulates of detent speed-raising radiating module, its computation process is as follows:

20431a, according to formula-h * A[T (t)-T _E] dt=m * c * dT (t), the transient behavior temperature T (t) that solves interior front axle brake device of the long Δ t of this time step and rear brake also deposits in the described storage unit synchronously, and the temperature parameter in the described storage unit is carried out real-time update, T in the formula _EBe environment temperature, h is the convection transfer rate of front axle brake device or rear brake, m _BfBe the quality of the rotary part of front axle brake device or rear brake, c is the specific heat of the material that rotary part adopts of front axle brake device or rear brake;

20431b, speed-raising heat radiation frictional behaviour are calculated: according to the front axle brake device that calculates among the funtcional relationship μ=f (T) of checking in the step 103 and the integrating step 20431a and the transient behavior temperature T (t) of rear brake, calculate front axle brake device and rear brake at this moment between hot coefficientoffriction in the step delta t _fAnd μ _r, and corresponding depositing in the storage unit;

20432, call the calculating in the next time step Δ t in the speed-raising heat radiation computation process that circulates of detent speed-raising radiating module, its computation process is as follows:

20432a, according to formula-h * A[T (t)-T _E] dt=m * c * dT (t), the transient behavior temperature T (t) that solves interior front axle brake device of the long Δ t of this time step and rear brake also deposits in the described storage unit synchronously, and the temperature parameter in the described storage unit is carried out real-time update;

20432b, speed-raising heat radiation frictional behaviour are calculated: according to the front axle brake device that calculates among the funtcional relationship μ=f (T) of checking in the step 103 and the integrating step 20432a and the transient behavior temperature T (t) of rear brake, calculate front axle brake device and rear brake at this moment between hot coefficientoffriction in the step delta t _fAnd μ _r, and corresponding depositing in the storage unit;

20433, return step 20432, the calculating of next time step Δ t in the speed-raising heat radiation computation process of proceeding to circulate constantly repeats and through m ₁=(t-n ₁* Δ t)/Δ t time step enters step 20434 after calculating, and the used time step number of speed-raising heat radiation computation process is m among this fade test ₁

2044, repeating step 2041 until finishing heat fading performance circulation virtual test m time, is then finished the temperature rise and the frictional behaviour virtual test process of described tested diaxon automobile front axle detent and rear brake to step 2043;

Step 2 is carried out in the virtual test process, export all computational datas of being stored in the described storage unit by the display that joins with described arithmetic processor and show synchronously, this moment, the temperature rise and the frictional behaviour virtual test process of tested each shaft brake of diaxon automobile finished.

2. according to the described diaxon running of claim 1 braking system I type braking ability heat fading virtual test method, it is characterized in that: after finishing the temperature rise and frictional behaviour virtual test process of described tested diaxon automobile front axle detent in the step 2044, also need utilize arithmetic processor and according to I type braking ability fade test method tested diaxon automobile is repeated to brake after the heat fading brake efficiency carry out virtual test, its test process may further comprise the steps:

301, initial parameter is set and storage: the heat fading brake efficiency after according to I type braking ability fade test method tested diaxon automobile being repeated to brake carries out the operating condition of test of virtual test, determine tested diaxon automobile is carried out the test parameters of virtual test, comprise the initial velocity V of brake to be tested vehicle of living in ₂And deposit in the storage unit synchronously;

302, the diaxon automobile dynamics model that utilizes in the step 202 to be set up, calculating at initial velocity is V ₂And the automobile brake distance and the braking deceleration of described diaxon automobile under the state that stops in emergency;

Carry out in the step 302 in the virtual test process, export all computational datas of being stored in the described storage unit by the display that joins with described arithmetic processor, tide of motorism decline brake efficiency test process finishes.

3. according to claim 1 or 2 described diaxon running braking system I type braking ability heat fading virtual test methods, it is characterized in that: many coupling analysis softwares described in the step 1021 are ADINA software.

4. according to claim 1 or 2 described diaxon running braking system I type braking ability heat fading virtual test methods, it is characterized in that: the conventional brake device temperature-raising experimental method described in the step 103 is for the constant speed temperature-raising experimental method that adopts the chassis multi-function test stand detent rear axle assy is carried out or adopt on the brake tester described brake assembly is carried out the constant speed temperature-raising experimental method.

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