CN103241238B - Hybrid electric vehicle descending auxiliary braking based on subjective intention and safety exits method - Google Patents

Abstract

The present invention disclose a kind of based on subjective intention and safety hybrid electric vehicle descending auxiliary braking exit method, comprise accelerate intention time auxiliary braking exit strategy and braking intention time auxiliary braking exit strategy.When finding that there is acceleration pedal signal, calculate the acceleration/accel a of vehicle on level road corresponding to acceleration pedal aperture, when a≤0, auxiliary brake torque does not exit; When after a > 0, auxiliary brake torque first to exit hydraulic braking, then exits motor braking, and the principle finally exiting Jake brake exits gradually.When finding that there is brake pedal signal, at total auxiliary brake torque T _sumbe before zero, increase brake pedal lock torque gradually and reduce T simultaneously _sum, but remaining total braking force moment preserving, the speed of a motor vehicle is also constant; T _sumafter equalling zero, increase brake pedal lock torque gradually auxiliary, total braking force square increases.Contemplated by the invention the auxiliary braking exit strategy under accelerating intention and under braking intention, there is great safety.

Description

Hybrid electric vehicle descending auxiliary braking based on subjective intention and safety exits method

Technical field

The present invention relates to vehicle descending auxiliary braking control technology, exit method particularly about hybrid vehicle descending auxiliary braking.

Background technology

Hybrid electric vehicle descending auxiliary braking, when referring to vehicle downhill running, is initiatively braked, to ensure that in vehicle sliding process, the speed of a motor vehicle does not increase by vehicle control device.But in auxiliary braking process, under the state that lock torque is larger, if controller obtains directly exiting auxiliary braking after chaufeur has the signal accelerating intention (acceleration pedal aperture is non-vanishing), all exiting suddenly with auxiliary brake torque, may be there is the uncontrollable instantaneous acceleration of chaufeur in vehicle, initiation potential; If controller obtains directly exiting auxiliary braking after chaufeur has the signal of braking intention (brake pedal aperture is non-vanishing), when chaufeur step on lock torque corresponding to brake pedal be less than auxiliary brake torque time, vehicle also there will be the speed of a motor vehicle and does not fall the anti-phenomenon increased.If exit auxiliary braking suddenly in maloperation situation, then more dangerous.These situations subjective intention that is obvious and chaufeur is not all inconsistent.

Therefore under the state considering vehicle safety, (vehicle-state controls by chaufeur all the time) can respond the driving intention of chaufeur all the time accurately, and have the ramp safe auxiliary braking of certain faults-tolerant control ability to exit method to chaufeur maloperation, the safe auxiliary braking of car ramp is controlled there is very important meaning.

In hybrid vehicle, what participate in descending auxiliary braking has driving engine, motor and hydraulic brake system, and in the process exiting auxiliary braking, the Controlling principle of entire car controller is: preferentially exit hydraulic auxiliary brake, next exits motor assist braking, finally exits driving engine auxiliary braking.Because driving engine auxiliary brake torque is only relevant to the speed of a motor vehicle under the state of the non-oil spout of driving engine, and descending auxiliary target when sliding exactly vehicle controlled to keep the speed of a motor vehicle not increase (maintaining the stable speed of a motor vehicle) by controller, therefore can suppose that driving engine auxiliary brake torque is constant, therefore the coordination problem of motor, driving engine and hydraulic combined auxiliary braking is studied, essence is exactly the coordination problem at research motor and hydraulic braking moment, exit in process at descending auxiliary braking, especially will consider the coordination exit strategy of motor and hydraulic pressure.

Summary of the invention

For above-mentioned research bottleneck, present invention incorporates the auxiliary braking feature of hybrid electric vehicle, propose a kind of hybrid electric vehicle descending auxiliary braking based on chaufeur subjective intention and vehicle safety and exit method.The method with the cooperation control of motor, hydraulic braking moment for core, relating to chaufeur has acceleration intention and chaufeur to have the exit strategy of braking intention two kinds of signals, make no matter under any signal, system can both the driving intention of accurate assurance chaufeur, and vehicle safety on ramp is accelerated or safe Reduced Speed Now.

The technical solution used in the present invention is: a kind of hybrid electric vehicle descending auxiliary braking based on subjective intention and safety exits method, and being included in chaufeur has the auxiliary braking exit strategy accelerated when being intended to, and it is characterized in that:

When finding that there is acceleration pedal signal, calculate the acceleration/accel of vehicle on level road corresponding to acceleration pedal aperture by formula (10):

$a=\frac{d{V}_i}{\mathrm{dt}}=(\frac{T_{d\_\mathrm{req}}}{r}-\frac{C_{D}A}{21.15}{V_i}^2-\mathrm{Gf})/\mathrm{\δm}---\left(10\right)$

Wherein, a, represent that the acceleration/accel on level road is expected value, T _{d_req}for drive torque corresponding under current vehicle speed and acceleration pedal, r is tire radius, and G is gravity suffered by vehicle, and f is surface resistance coefficient, C _dfor aerodynamic drag factor, A is the wind area of vehicle, V _ifor car speed, δ is vehicle rotary mass conversion coefficient, and m is car mass;

1) when a≤0, auxiliary brake torque does not exit;

2) when after a > 0, auxiliary brake torque first to exit hydraulic braking, then exits motor braking, and the principle finally exiting Jake brake exits gradually, and concrete grammar is as follows:

1. system log (SYSLOG) previous moment motor assist lock torque assignment are to electric machine controller, make T ' _pM=T _{a_PM}=T ' _pM-last, T ' _pMfor real-time electric system control torque bid value, T _{a_PM}for acceleration pedal exits the motor assist lock torque record value of auxiliary braking system previous moment, T ' _pM-lastfor acceleration pedal exits the motor assist lock torque instantaneous value of auxiliary braking system previous moment;

System log (SYSLOG) previous moment hydraulic auxiliary brake moment assignment, to hydraulic control pump, make T ' _hyd=T _{a_hyd}=T ' _hyd-last, wherein T ' _hydfor real-time HYDRAULIC CONTROL SYSTEM torque command value, T _{a_hyd}for acceleration pedal exits the hydraulic auxiliary brake moment record value of auxiliary braking system previous moment, T ' _hyd-lastfor acceleration pedal exits the hydraulic auxiliary brake moment value of auxiliary braking system previous moment;

System assigned value is T ' to the brake command of driving engine _eng=0, T ' _engfor real-time Jake brake moment order;

Under calculating current acceleration pedal and the speed of a motor vehicle by formula (10), the acceleration/accel of vehicle on level road;

2. first system discharges hydraulic braking moment:

As T ' _hyd> k _hyd*during a, order

T′ _hyd＝T _{a_hyd}+k _hyd*∫adt (11)

T ' now _hydit is exactly hydraulic braking moment release value;

Wherein k _hydobtaining value method as follows:

According to following relational expression:

$\left\{\begin{array}{c}\mathrm{\ΣF}=\mathrm{Gf}\cos \mathrm{\α}+\frac{C_{D}A}{21.15}{V_i}^2+G\sin \mathrm{\α}+\mathrm{\δm}\frac{d{V}_i}{\mathrm{dt}}\\ F_t=T_{\mathrm{sum}}/r\\ \mathrm{\ΣF}=F_t\\ T_{\mathrm{sum}}=T_{\mathrm{PM}}^{\′}+T_{\mathrm{hyd}}^{\′}+T_{\mathrm{eng}}^{\′}\\ a=\frac{{\mathrm{dV}}_i}{\mathrm{dt}}=(\frac{T_{d\_\mathrm{req}}}{r}-\frac{C_{D}A}{21.15}{V_i}^2-\mathrm{Gf})/\mathrm{\δm}\\ T_{\mathrm{hyd}}^{\′}=T_{a\_\mathrm{hyd}}+k_{\mathrm{hyd}}*\∫\mathrm{adt}\end{array}\right.$

∑ F represents the total drag suffered by vehicle, F _trepresent the braking external force suffered by vehicle, G represents gravity suffered by vehicle, and f represents surface resistance coefficient, and α represents road gradient, C _drepresent aerodynamic drag factor, A represents the wind area of vehicle, V _irepresent the speed of vehicle, δ represents vehicle rotary mass conversion coefficient, and m represents car mass, T _sumrepresent total auxiliary brake torque, r represents tire radius,

Get different acceleration pedal aperture, the speed of a motor vehicle and ratio of slope, try to achieve several k _hydvalue, gets wherein k _hydthe value that the frequency of occurrences is maximum is required k _hydvalue;

As T ' _hyd≤ k _hyd*during a, make T ' _hyd=T _{req_hyd},

Wherein T _{req_hyd}for the hydraulic brake system order of real-time operator demand, T ' now _hydit is exactly hydraulic braking moment release value;

3. start to discharge motor assist lock torque after system release hydraulic braking moment:

As T ' _pMduring < 0, order

T′ _PM＝T _{a_PM}+k _PM*∫adt (12)

T ' now _pMit is exactly motor assist lock torque release value; Wherein k _pmobtaining value method as follows:

$\left\{\begin{array}{c}\mathrm{\&Sigma;F}=\mathrm{Gf}\cos \mathrm{\&alpha;}+\frac{C_{D}A}{21.15}{V_i}^2+G\sin \mathrm{\&alpha;}+\mathrm{\&delta;m}\frac{d{V}_i}{\mathrm{dt}}\\ F_t=T_{\mathrm{sum}}/r\\ \mathrm{\&Sigma;F}=F_t\\ T_{\mathrm{sum}}=T_{\mathrm{PM}}^{\&prime;}+T_{\mathrm{hyd}}^{\&prime;}+T_{\mathrm{eng}}^{\&prime;}\\ a=\frac{{\mathrm{dV}}_i}{\mathrm{dt}}=(\frac{T_{d\_\mathrm{req}}}{r}-\frac{C_{D}A}{21.15}{V_i}^2-\mathrm{Gf})/\mathrm{\&delta;m}\\ T_{\mathrm{PM}}^{\&prime;}=T_{a\_\mathrm{PM}}+k_{\mathrm{PM}}*\&Integral;\mathrm{adt}\end{array}\right.$

Get different acceleration pedal aperture, the speed of a motor vehicle and ratio of slope, try to achieve several k _pMvalue, gets wherein k _pMthe value that the frequency of occurrences is maximum is required k _pMvalue;

As T ' _pMwhen>=0,

Make the order that the order of electric machine controller equals at that time corresponding to chaufeur acceleration pedal, the order of engine controller equals the order at that time corresponding to chaufeur acceleration pedal, all discharges, shown in (13):

$\left\{\begin{array}{c}{T}_{\mathrm{PM}}^{\&prime;}=T_{\mathrm{req}\_\mathrm{PM}}\\ T_{\mathrm{eng}}^{\&prime;}=T_{\mathrm{req}\_\mathrm{eng}}\end{array}\right.---\left(13\right)$

So far vehicle completes auxiliary braking and exits process.

The present invention is also included in auxiliary braking exit strategy when chaufeur has a braking intention, and its concrete grammar is:

When finding that there is brake pedal signal, according to formula (14):

F _t″＝T _sum/r+T _{d_b_req}/r (14)

Wherein F _t" represent total braking force, T _sumrepresent total auxiliary brake torque, T _{d_b_req}represent chaufeur step on lock torque corresponding to brake pedal,

At T _sumbefore equalling zero, remain F _t" * r is constant, and the speed of a motor vehicle is also constant, increases T gradually _{d_b_req}and reduce T thereupon _sum, until T _{d_b_req}be increased to F _t" * r, T _sumtill equalling zero, auxiliary braking all exits.

At T _sumafter equalling zero, T _{d_b_req}continue to increase, F _t" also increase, car load speed decreases thereupon.

The present invention is owing to taking above technical scheme, and its beneficial effect had is:

1, chaufeur has the descending auxiliary braking Safe withdrawing strategy accelerating intention to solve the subject matter of three aspects: the acceleration demand one, responding chaufeur; Two, prevent because excessive auxiliary brake torque exits suddenly, cause vehicle because of acceleration/accel excessive and out of control; Three, prevent from, because chaufeur is to the maloperation of acceleration pedal, causing additional braking force to exit suddenly, cause vehicle to accelerate suddenly the danger caused.Descending auxiliary braking Safe withdrawing for judging target with a certain accekeration, both can ensure that the acceleration of vehicle response chaufeur is expected, also can ensure that the acceleration/accel of vehicle is in the acceleration pedal controlled range of chaufeur simultaneously.Exiting suddenly and danger that chaufeur causes the maloperation of acceleration pedal of additional braking force when the gradient is comparatively large, the speed of a motor vehicle is higher can be avoided.

2, chaufeur has the descending auxiliary braking Safe withdrawing strategy of braking intention, after making controller receive the non-vanishing signal of brake pedal aperture, both can not occur because exiting auxiliary braking suddenly that the speed of a motor vehicle increased, also vehicle can not be caused just to exit auxiliary braking when braking force that chaufeur is stepped on does not reach requirement and cause speed of a motor vehicle increase instantaneously, improve the safety of vehicle.

3, first exit hydraulic auxiliary brake moment, then exit motor assist lock torque, that finally exits driving engine auxiliary brake torque exits order, not only can ensure the economy of Vehicular system, and can avoid the frequent access of driving engine and exit.

Accompanying drawing explanation

Fig. 1 is the acceleration/accel of vehicle weight generation and the graph of a relation of the speed of a motor vehicle under different gradient;

Fig. 2 is the logic diagram exiting auxiliary braking under chaufeur has acceleration intention situation.

Detailed description of the invention

Method of the present invention is illustrated below in conjunction with drawings and Examples.

The present invention mainly studies the exit strategy of ramp safe auxiliary braking system under chaufeur has acceleration intention situation and the exit strategy under chaufeur has braking intention situation.

One, chaufeur has the auxiliary braking exit strategy accelerating intention

Chaufeur has the exit strategy accelerating intention mainly to solve brake controller after receiving the non-vanishing signal of acceleration pedal aperture, the acceleration demand of chaufeur can be responded, after receiving acceleration pedal signal, auxiliary braking can not be exited completely immediately again, cause and occur vehicle acceleration not by the situation that chaufeur controls.

By running car equation (1), and the force bearing formulae of vehicle under auxiliary brake torque (2), the composition formula (3) of auxiliary brake torque:

$\mathrm{\&Sigma;F}=\mathrm{Gf}\cos \mathrm{\&alpha;}+\frac{C_{D}A}{21.15}{V_i}^2+G\sin \mathrm{\&alpha;}+\mathrm{\&delta;m}\frac{{\mathrm{dV}}_i}{\mathrm{dt}}---\left(1\right)$

F _t＝T _sum/r (2)

T _sum＝T′ _PM+T′ _hyd+T′ _eng(3)

∑ F represents the total drag suffered by vehicle, F _trepresent the braking external force suffered by vehicle, G represents gravity suffered by vehicle, and f represents surface resistance coefficient, and α represents road gradient, C _drepresent aerodynamic drag factor, A represents the wind area of vehicle, V _irepresent the speed of vehicle, δ represents vehicle rotary mass conversion coefficient, and m represents car mass, T _sumrepresent total auxiliary brake torque, r represents tire radius, T ' _pMfor real-time electric system control command, T ' _hydfor real-time HYDRAULIC CONTROL SYSTEM torque command value, T ' _engfor real-time Jake brake moment bid value.

Known, in vehicle at the uniform velocity driving process, both do not have acceleration pedal aperture non-vanishing do not have brake pedal aperture non-vanishing yet signal time, the total drag suffered by vehicle, with suffered by total auxiliary braking external force equal, that is: ∑ F=F _t.Now vehicle is average rate, and resistance due to acceleration is zero, therefore by formula (1), formula (2) available equation is:

$T_{\mathrm{sum}}/r=\mathrm{Gf}\cos \mathrm{\&alpha;}+\frac{C_{D}A}{21.15}{V_i}^2+G\sin \mathrm{\&alpha;}---\left(4\right)$

When acceleration pedal opening amount signal is non-vanishing, if additional braking force all exits, and directly respond the drive torque of chaufeur acceleration pedal, now auxiliary brake torque vanishing, then the external force suffered by vehicle is the expectation propulsive effort F of chaufeur _t', that is:

F _t′＝T _d-req/r (5)

T _{d_req}drive torque corresponding under representing current vehicle speed and acceleration pedal.

Vehicle is in downhill running process, acceleration pedal enters supposes that the speed of a motor vehicle is constant instantaneously, the gradient is constant, the pavement friction resistance that then automobile is all, the resistance of wind and grade resistance all constant (the equational first three items of running car), total drag then suffered by vehicle is equal with total propulsive effort, that is: ∑ F=F _t'.By formula (1), formula (5) can obtain acceleration pedal exit after equation be:

$T_{d\_\mathrm{req}}/r=\mathrm{Gf}\cos \mathrm{\&alpha;}+\frac{C_{D}A}{21.15}{V_i}^2+G\sin \mathrm{\&alpha;}+\mathrm{\&delta;m}\frac{{\mathrm{dV}}_i}{\mathrm{dt}}---\left(6\right)$

If acceleration pedal enter before and after moment, residing for the speed of a motor vehicle and vehicle, the gradient does not all change, then can be obtained by formula (4), formula (6):

$(T_{d\_\mathrm{req}}-T_{\mathrm{sum}})/r=\mathrm{\&delta;m}\frac{{\mathrm{dV}}_i}{\mathrm{dt}}---\left(7\right)$

Arrangement formula (7) can obtain vehicle instantaneous acceleration/accel after acceleration pedal is got involved:

$\frac{{\mathrm{dV}}_i}{\mathrm{dt}}=(T_{d\_\mathrm{req}}-T_{\mathrm{sum}})/\mathrm{r\&delta;m}---\left(8\right)$

Utilize running car equation and certain money 1.6 liters of automobile correlation parameters, acceleration/accel when calculating vehicle sliding under different gradient and speed as shown in Figure 1, in the gradient, the less or speed of a motor vehicle is higher than after 60 kilometers, the vehicle acceleration caused by the gradient is little, now under acceleration pedal signal, exit auxiliary braking, the acceleration/accel of vehicle is produced by the drive torque demand of chaufeur substantially, and vehicle is in chaufeur can state of a control; But in the gradient under the comparatively large or lower state of the speed of a motor vehicle, the vehicle acceleration caused by the gradient is then larger, now under acceleration pedal signal, exit auxiliary braking, the acceleration/accel that the drive torque demand that the acceleration/accel of vehicle then equals chaufeur produces and auxiliary brake torque exit the acceleration/accel sum that rear grade resistance produces.Wherein the acceleration/accel that produces of grade resistance is only relevant with the gradient, is that chaufeur is uncontrollable, and first this is not inconsistent with the driving intention of chaufeur, next due to this acceleration/accel be not that chaufeur subjective desire is conceivable, then likely cause potential safety hazard.So acceleration pedal exits in auxiliary braking process and must be controlled exiting of auxiliary brake torque.

Chaufeur utilizes acceleration and brake pedal to realize to the adjustment of car speed, if any acceleration pedal signal in auxiliary braking process, the subjective intention of chaufeur is that desired speed increases, but the amplitude (acceleration/accel) increased still should be controlled by chaufeur.Therefore the present invention is in the process of the safe auxiliary braking of descending, with the acceleration/accel of the vehicle corresponding to drive torque corresponding to acceleration pedal aperture and this drive torque on level road for target, shown in (10), and release auxiliary brake torque.

Owing to travelling road gradient α=0 on level road, then formula (6) becomes:

$T_{d\_\mathrm{req}}/r=\mathrm{Gf}+\frac{C_{D}A}{21.15}{V_i}^2+\mathrm{\&delta;m}\frac{{\mathrm{dV}}_i}{\mathrm{dt}}---\left(9\right)$

Arrangement can obtain:

$a=\frac{{\mathrm{dV}}_i}{\mathrm{dt}}=(\frac{T_{d\_\mathrm{req}}}{r}-\frac{C_{D}A}{21.15}{V_i}^2-\mathrm{Gf})/\mathrm{\&delta;m}---\left(10\right)$

Wherein a is the acceleration/accel expected value on level road.

When a≤0, auxiliary brake torque does not exit;

When after a > 0, auxiliary brake torque just can reduce, until be reduced to zero, the auxiliary brake torque rear vehicle that equals zero responds the drive torque of chaufeur again.Auxiliary brake torque first to exit hydraulic braking, then exits motor braking, and the principle finally exiting Jake brake exits gradually, and with reference to flow process shown in Fig. 2, concrete grammar is as follows:

In vehicle descending auxiliary braking process when finding acceleration pedal opening amount signal Pa > 0 (Pa is acceleration pedal opening value),

1) system log (SYSLOG) previous moment (during Pa=0) electric system auxiliary brake torque and be assigned to electric machine controller, at this moment T ' _pM=T _{a_PM}=T ' _pM-last, record previous moment hydraulic auxiliary brake moment is also assigned to hydraulic control pump, same T ' _hyd=T _{a_hyd}=T ' _hyd-last, and be zero, T ' by the torque command assignment of driving engine _eng=0, under calculating current acceleration pedal and the speed of a motor vehicle by formula (10), the acceleration/accel of vehicle on level road.

Wherein, T _{a_PM}for acceleration pedal exits the motor assist lock torque record value of auxiliary braking system previous moment, T ' _pM-lastfor acceleration pedal exits the motor assist lock torque instantaneous value of auxiliary braking system previous moment, T _{a_hyd}for acceleration pedal exits the hydraulic auxiliary brake moment record value of auxiliary braking system previous moment, T ' _hyd-lastfor acceleration pedal exits the hydraulic auxiliary brake moment value of auxiliary braking system previous moment.

2) first system discharges hydraulic braking moment

1. as T ' _hyd> k _hyd*during a, order

T′ _hyd＝T _{a_hyd}+k _hyd*∫adt (11)

Wherein k _hydobtaining value method as follows:

Get different acceleration pedal aperture, the speed of a motor vehicle and ratio of slope, can k be tried to achieve by formula (1), formula (2), formula (3), formula (10) and formula (11) _hydscope, get wherein k _hydthe maximum value of the frequency of occurrences is for k _hydvalue.

2. as T ' _hyd≤ k _hyd*during a, T ' now _hydvalue, equal with the actual demand of chaufeur, so make T ' _hyd=T _{req_hyd},

Wherein T _{req_hyd}for the hydraulic brake system order of real-time operator demand.

After 3) system discharges hydraulic braking moment (T ' _hyd=T _{req_hyd}), start to discharge motor assist lock torque,

1. as T ' _pMduring < 0, order

T′ _PM＝T _{a_PM}+k _PM*∫adt (12)

Wherein k _pMobtaining value method as follows:

Get different acceleration pedal aperture, the speed of a motor vehicle and ratio of slope, can k be tried to achieve by formula (1), formula (2), formula (3), formula (10) and formula (12) _pMscope, get wherein k _pMthe maximum value of the frequency of occurrences is for k _pMvalue.

2. as T ' _pMwhen>=0,

Make the order that the order of electric machine controller equals at that time corresponding to chaufeur acceleration pedal, the order of engine controller equals the order at that time corresponding to chaufeur acceleration pedal, shown in (13):

$\left\{\begin{array}{c}{T}_{\mathrm{PM}}^{\&prime;}=T_{\mathrm{req}\_\mathrm{PM}}\\ T_{\mathrm{eng}}^{\&prime;}=T_{\mathrm{req}\_\mathrm{eng}}\end{array}\right.---\left(13\right)$

So far vehicle completes auxiliary braking and exits process, the operation of totally linearization chaufeur, and its idiographic flow as shown in Figure 2.First exit hydraulic auxiliary brake moment, then exit motor assist lock torque, that finally exits driving engine auxiliary brake torque exits order, not only can ensure the economy of Vehicular system, and can avoid the frequent access of driving engine and exit.

Two, chaufeur has the auxiliary braking exit strategy of braking intention

In ramp safe auxiliary braking process, brake pedal exit strategy mainly solves after controller receives the non-vanishing signal of brake pedal aperture, there will not be vehicle to step on lock torque T at chaufeur _{d_b_req}do not reach auxiliary brake torque to exit suddenly instantaneously, and the problem causing the speed of a motor vehicle to increase.

Still by formula (1), formula (2)

$\mathrm{\&Sigma;F}=\mathrm{Gf}\cos \mathrm{\&alpha;}+\frac{C_{D}A}{21.15}{V_i}^2+G\sin \mathrm{\&alpha;}+\mathrm{\&delta;m}\frac{{\mathrm{dV}}_i}{\mathrm{dt}}---\left(1\right)$

F _t＝T _sum/r (2)

Known, when auxiliary brake torque is larger, when the lock torque corresponding to brake pedal is less than slope road auxiliary brake torque, the increase of the speed of a motor vehicle will be caused as directly exited auxiliary brake torque; Namely the lock torque that brake pedal is corresponding is little equal slope road auxiliary brake torque time, if auxiliary brake torque directly exits, will make vehicle instantaneously produce with (T _sum-T _{d_b_req}) corresponding acceleration/accel, not only can affect to the psychology of chaufeur, and this acceleration/accel produced suddenly also may impact traffic safety.

The brake system that auxiliary braking system can control has motor braking system, engine braking system and hydraulic brake system.And step on brake pedal at chaufeur, before vehicle control device does not also exit ramp safe auxiliary braking, brake pedal can only control vacuum assisted hydraulic brake system.Hydraulic brake master cylinder can overlap independent systems force in parallel by electromagnet core or brake pedal push rod two, namely automatically controlled and chaufeur control two cover brake system work independently non-interference, same electronic vacuum brake system and motor braking system are also non-interference on controlling, therefore can exit under brake pedal during the safe auxiliary braking in slope road controls and realize chaufeur control and the auxiliary cooperation control controlled, namely realize the auxiliary braking exit strategy being reduced to threshold values with the speed of a motor vehicle.

Under brake pedal effect, total braking force square F _t" lock torque corresponding for brake pedal and slope road auxiliary brake torque sum, shown in (14),

F _t″＝T _sum/r+T _{d_b_req}/r (14)

Do not having under accelerator load, the total drag suffered by vehicle with suffered by total braking external force equal, that is: ∑ F=F _t".

Total braking requirement of vehicle is determined by the vehicle place gradient and the speed of a motor vehicle, controls, T owing to not yet exiting ramp safe auxiliary braking _sumcontrol objectives remain the speed of a motor vehicle and do not increase, therefore along with T _{d_b_req}increase T _sumreduce gradually; Until T _{d_b_req}be increased to F _t" * r, T _sumjust can equal zero, at T _sumtotal braking force square F suffered by the vehicle in front equalled zero _t" * r remains unchanged, and the speed of a motor vehicle also remains unchanged; T _sumafter equalling zero, T _{d_b_req}continue to increase, F _t" increase car load speed also just decreases by * r.

This strategy both can ensure, in ramp safe auxiliary braking control process, to there will not be the speed of a motor vehicle to increase when exiting with brake pedal signal, and the non-step that also can realize auxiliary brake torque exits, to improve the safety of vehicle.

Claims (3)

1. the hybrid electric vehicle descending auxiliary braking based on subjective intention and safety exits a method, and being included in chaufeur has the auxiliary braking exit strategy accelerated when being intended to, and it is characterized in that:

When finding that there is acceleration pedal signal, calculate the acceleration/accel of vehicle on level road corresponding to acceleration pedal aperture by formula (10):

$a=\frac{d{V}_i}{\mathrm{dt}}=(\frac{T_{d\_\mathrm{req}}}{r}-\frac{C_{D}A}{21.15}{V_i}^2-\mathrm{Gf})/\mathrm{\&delta;m}---\left(10\right)$

Wherein, a, represent that the acceleration/accel on level road is expected value, T _{d_req}for drive torque corresponding under current vehicle speed and acceleration pedal, r is tire radius, and G is gravity suffered by vehicle, and f is surface resistance coefficient, C _dfor aerodynamic drag factor, A is the wind area of vehicle, V _ifor car speed, δ is vehicle rotary mass conversion coefficient, and m is car mass;

1) when a≤0, auxiliary brake torque does not exit;

2) when after a > 0, auxiliary brake torque first to exit hydraulic braking, then exits motor braking, and the principle finally exiting Jake brake exits gradually, and concrete grammar is as follows:

1. system log (SYSLOG) previous moment motor assist lock torque assignment are to electric machine controller, make T ' _pM=T _{a_PM}=T ' _pM-last, T ' _pMfor real-time electric system control torque bid value, T _{a_PM}for acceleration pedal exits the motor assist lock torque record value of auxiliary braking system previous moment, T ' _pM-lastfor acceleration pedal exits the motor assist lock torque instantaneous value of auxiliary braking system previous moment;

System log (SYSLOG) previous moment hydraulic auxiliary brake moment assignment, to hydraulic control pump, make T ' _hyd=T _{a_hyd}=T ' _hyd-last, wherein T ' _hydfor real-time HYDRAULIC CONTROL SYSTEM torque command value, T _{a_hyd}for acceleration pedal exits the hydraulic auxiliary brake moment record value of auxiliary braking system previous moment, T ' _hyd-lastfor acceleration pedal exits the hydraulic auxiliary brake moment value of auxiliary braking system previous moment;

System assigned value is T ' to the brake command of driving engine _eng=0, T ' _engfor real-time Jake brake moment order;

Under calculating current acceleration pedal and the speed of a motor vehicle by formula (10), the acceleration/accel of vehicle on level road;

2. first system discharges hydraulic braking moment:

As T ' _hyd> k _hyd*during a, order

T′ _hyd＝T _{a_hyd}+k _hyd*∫adt (11)

T ' now _hydit is exactly hydraulic braking moment release value;

Wherein k _hydobtaining value method as follows:

According to following relational expression:

$\left\{\begin{array}{c}\mathrm{\&Sigma;F}=\mathrm{Gf}\cos \mathrm{\&alpha;}+\frac{C_{D}A}{21.15}{V_i}^2+G\sin \mathrm{\&alpha;}+\mathrm{\&delta;m}\frac{d{V}_i}{\mathrm{dt}}\\ F_t=T_{\mathrm{sum}}/r\\ \mathrm{\&Sigma;F}=F_t\\ T_{\mathrm{sum}}=T_{\mathrm{PM}}^{\&prime;}+T_{\mathrm{hyd}}^{\&prime;}+T_{\mathrm{eng}}^{\&prime;}\\ a=\frac{{\mathrm{dV}}_i}{\mathrm{dt}}=(\frac{T_{d\_\mathrm{req}}}{r}-\frac{C_{D}A}{21.15}{V_i}^2-\mathrm{Gf})/\mathrm{\&delta;m}\\ T_{\mathrm{hyd}}^{\&prime;}=T_{a\_\mathrm{hyd}}+k_{\mathrm{hyd}}*\&Integral;\mathrm{adt}\end{array}\right.$

∑ F represents the total drag suffered by vehicle, F _trepresent the braking external force suffered by vehicle, G represents gravity suffered by vehicle, and f represents surface resistance coefficient, and α represents road gradient, C _drepresent aerodynamic drag factor, A represents the wind area of vehicle, V _irepresent the speed of vehicle, δ represents vehicle rotary mass conversion coefficient, and m represents car mass, T _sumrepresent total auxiliary brake torque, r represents tire radius,

Get different acceleration pedal aperture, the speed of a motor vehicle and ratio of slope, try to achieve several k _hydvalue, gets wherein k _hydthe value that the frequency of occurrences is maximum is required k _hydvalue;

As T ' _hyd≤ k _hyd*during a, make T ' _hyd=T _{req_hyd},

Wherein T _{req_hyd}for the hydraulic brake system order of real-time operator demand, T ' now _hydit is exactly hydraulic braking moment release value;

3. start to discharge motor assist lock torque after system release hydraulic braking moment:

As T ' _pMduring < 0, order

T′ _PM＝T _{a_PM}+k _PM*∫adt (12)

T ' now _pMit is exactly motor assist lock torque release value; Wherein k _pmobtaining value method as follows:

$\left\{\begin{array}{c}\mathrm{\&Sigma;F}=\mathrm{Gf}\cos \mathrm{\&alpha;}+\frac{C_{D}A}{21.15}{V_i}^2+G\sin \mathrm{\&alpha;}+\mathrm{\&delta;m}\frac{d{V}_i}{\mathrm{dt}}\\ F_t=T_{\mathrm{sum}}/r\\ \mathrm{\&Sigma;F}=F_t\\ T_{\mathrm{sum}}=T_{\mathrm{PM}}^{\&prime;}+T_{\mathrm{hyd}}^{\&prime;}+T_{\mathrm{eng}}^{\&prime;}\\ a=\frac{{\mathrm{dV}}_i}{\mathrm{dt}}=(\frac{T_{d\_\mathrm{req}}}{r}-\frac{C_{D}A}{21.15}{V_i}^2-\mathrm{Gf})/\mathrm{\&delta;m}\\ T_{\mathrm{PM}}^{\&prime;}=T_{a\_\mathrm{PM}}+k_{\mathrm{PM}}*\&Integral;\mathrm{adt}\end{array}\right.$

Get different acceleration pedal aperture, the speed of a motor vehicle and ratio of slope, try to achieve several k _pMvalue, gets wherein k _pMthe value that the frequency of occurrences is maximum is required k _pMvalue;

As T ' _pMwhen>=0,

Make the order that the order of electric machine controller equals at that time corresponding to chaufeur acceleration pedal, the order of engine controller equals the order at that time corresponding to chaufeur acceleration pedal, all discharges, shown in (13):

$\left\{\begin{array}{c}{T}_{\mathrm{PM}}^{\&prime;}=T_{\mathrm{req}\_\mathrm{PM}}\\ T_{\mathrm{eng}}^{\&prime;}=T_{\mathrm{req}\_\mathrm{eng}}\end{array}\right.---\left(13\right)$

So far vehicle completes auxiliary braking and exits process.

2. the hybrid electric vehicle descending auxiliary braking based on subjective intention and safety according to claim 1 exits method, it is characterized in that: be also included in auxiliary braking exit strategy when chaufeur has a braking intention, its concrete grammar is:

When finding that there is brake pedal signal, according to formula (14):

F _t”＝T _sum/r+T _{d_b_req}/r (14)

Wherein F _t" represent total braking force, T _sumrepresent total auxiliary brake torque, T _{d_b_req}represent chaufeur step on lock torque corresponding to brake pedal,

At T _sumbefore equalling zero, remain F _t" * r is constant, the speed of a motor vehicle is also constant, increases T gradually _{d_b_req}and reduce T thereupon _sum, until T _{d_b_req}be increased to F _t" * r, T _sumtill equalling zero, auxiliary braking all exits.

3. the hybrid electric vehicle descending auxiliary braking based on subjective intention and safety according to claim 2 exits method, it is characterized in that: at T _sumafter equalling zero, T _{d_b_req}continue to increase, F _t" also increase, car load speed decreases. thereupon