CN101479508A - Method of controlling a transmission ratio - Google Patents

Abstract

The invention relates to a method for controlling a transmission ratio (r) of a continuously adjustable transmission (3). An accelerator pedal position and an actual driving speed (vuactual) are acquired. By consideration of the actual driving speed (vactual) and the accelerator pedal position (aPedal), a transmission gradient is determined. A target transmission ratio is determined as the sum of an actual transmission ratio (ractual) and a transmission adjustment value (formula I), and the continuously adjustable transmission (3) is set to this ratio.

Description

The method of control velocity ratio

Technical field

The present invention relates to a kind of method of controlling the velocity ratio of stepless speed variator.

Background technique

In the transmission device of the utility vehicle of for example wheel loader, adopt dynamic pressure gear or static pressure driving mechanism usually.When adopting the dynamic pressure gear, the driver controls the fuel injection amount of diesel engine by accelerator pedal position.The stable drive ratio of dynamic pressure gear makes and produces direct correlation between set diesel engine speed and the travelling speed.But during a work running, for example promote the full shovel that carries, diesel engine can must be used for hydraulic system of working with a big chunk that drives energy.This just requires diesel engine to have a high constant rotating speed.For fear of unconsciously increasing travelling speed simultaneously, so-called by handling " fine motion pedal " regulates flowing of driving mechanism, or limits by the operation break, thereby utilizes transducer to obtain differential rotating speed.

In the static pressure driving mechanism, so-called " travelling automatically " realizes by hydraulic regulating device.As stepless speed variator, the static pressure gear unit comprises at least one oil hydraulic pump and an oil hydraulic motor, and wherein the angle of revolution of at least one oil hydraulic pump is adjustable.The supercharging of accelerator pedal position and diesel engine is depended in the adjusting of angle of revolution.Therefore, in the static pressure driving mechanism, the diesel engine speed that sets is also depended in the adjusting of static pressure gear unit.

Summary of the invention

Therefore main purpose of the present invention provides a kind of method of controlling the stepless speed variator velocity ratio, therefore it can irrespectively be regulated with the rotating speed of diesel engine and for the driver provides the excellent operation travelling comfort, expects because the accelerator pedal position of being preset by the driver can realize specific acceleration.

This purpose realizes by the described method of feature that has in the claim 1 of the present invention.

According to the method for claim 1,, at first detect accelerator pedal position α in order to control the velocity ratio of stepless speed variator _PedalThe actual travel speed of putting inspection vehicle in addition at any time is as the actual travel speed v _IstBy considering accelerator pedal position α _PedalWith the actual travel speed v _IstDetermine the velocity ratio variance ratio

Under these circumstances, velocity ratio variance ratio

Expression static pressure gear unit velocity ratio r _Soll(t) variation of time per unit.Based on actual transmission ratio and velocity ratio variance ratio

Set a new target gear ratio value r _Soll(t+ Δ t), described new target gear ratio value is the velocity ratio variance ratio

Compare sum with the product of time lag Δ t with actual transmission.

The advantage of the inventive method is, influences velocity ratio r by being preset in during giving it the gun _SollThe speed that changes realizes quickening.Therefore based on corresponding accelerator pedal position α _Pedal, just can realize specific acceleration expectation.Therefore can be during diesel engine to travel and in the hydraulic system of working work, setting can provide high output needed constant rotating speed.From this constant rotational speed begin but with the rotational speed regulation of diesel engine irrespectively, by independent adjusting for example the transmission of the stepless speed variator of static pressure gear unit recently realize the acceleration of vehicle.Also can expect using mechanical continuously-variable transmission to replace stepless speed variator with the static pressure gear unit form that has pump-motor combination.

Provide other favourable improvement projects of the inventive method in the dependent claims.

Particularly advantageously be, by calcuating correction value α _{Pedal, grenz}Consider travelling speed v _Ist, wherein said correction value α _{Pedal, grenz}Comprise actual travel speed v by vehicle _IstWith maximum travelling speed v _MaxThe ratio of forming.Particularly advantageously be, with correction value α _{Pedal, grenz}With detect accelerator pedal position α _PedalCombination is quickened the expectation eigenvalue to form one, and wherein said eigenvalue is to determine the velocity ratio variance ratio

The basis.The acceleration expectation that shows except the driver is actual outside the promptly default specific accelerator pedal position, also will be considered the actual travel speed v of vehicle _IstTherefore, can be simply according to actual travelling speed v _IstObtain target velocity ratio r _SollVariation.

In such cases, quicken expectation eigenvalue (α _Pedal-α _{Pedal, grenz}) be preferably formed and be the poor (α between detected accelerator pedal position and correction value _Pedal-α _{Pedal, grenz}).Therefore, described acceleration expectation eigenvalue (α _Pedal-α _{Pedal, grenz}) can be used for nearly all final formation transmission variance ratio

Function.Under the simplest situation, this carries out according to linear equation.But, also can be by being different from the suitable parametrization of above-mentioned equation, the characteristic curve shape of typical case's behavior when obtaining another corresponding to the pilot control accelerator pedal.

In addition advantageously, as calcuating correction value (α _Pedal-α _{Pedal, grenz}) time, also consider and remove the actual travel speed v _IstOutside another output requirement.Described another output requires for example can be based on determining from the signal of fine motion pedal.The driver of the utility vehicle of this for example wheel loader is at fine motion pedal position α _InchAssistance under, which part that can determine to export is used for hydraulic system of working.The remaining part of output is used for driving mechanism.Because the output that limits requires to be included in correction value (α by this way _Pedal-α _{Pedal, grenz}) in, so not only consider current travelling speed v _Ist, and consider that the requirement of other outputs sets up the velocity ratio variance ratio The acceleration that changes requires a low output, because for example for acceleration, the velocity ratio variance ratio is chosen to correspondingly lower.

Description of drawings

Accompanying drawing shows the method for control velocity ratio r (t) with the form of chart, and illustrates in more detail in the following description.In described accompanying drawing:

Fig. 1 illustrates the schematic representation of carrying out the driving mechanism of controlling method among the present invention;

Fig. 2 illustrates the process simplification figure of the controlling method among the present invention;

Fig. 3 illustrates the chart of explanation driven strategy works of the present invention;

Fig. 4 illustrates first embodiment of certain given travel state;

Fig. 5 illustrates second embodiment of certain given travel state; And

Fig. 6 illustrates the 3rd embodiment of another given travel state.

Embodiment

Before carrying out method of the present invention, at first the driving mechanism 1 to this method of use of utility vehicle is described.This driving mechanism 1 shown in Fig. 1.Described driving mechanism 1 drives by the diesel engine 2 as first driving source.Described diesel engine 2 links to each other with output branch transmission system 3.The described branch's transmission system 3 of exporting comprises the first output branch that is designed to static pressure gear unit 4.Be provided with the mechanical type branch 5 of transmission system abreast with the first output branch.

The static pressure gear unit 4 of transmission system links to each other with vehicle driven shaft 6 with mechanical type branch 5.For this reason, output branch transmission system comprises the gear unit section (Summiergetriebeabschnitt) 50 that adds up that is designed to planetary gear unit.

Diesel engine 2 is connected to the input end that the transmission shaft 7 of exporting branch's transmission system 3 is located at transmission system.At output terminal, output branch transmission system 3 is connected to for example rear axle differential of driven vehicle with output shaft 8.

Static pressure gear unit 4 comprises oil hydraulic pump 9 and oil hydraulic motor 10.Be connected with each other at oil hydraulic pump 9 described in the closed loop Hydraulic Power Transmission System and oil hydraulic motor 10.For this reason, oil hydraulic pump 9 is connected with second active line 12 by first active line 11 respectively with oil hydraulic motor 10.

The quantity delivered of oil hydraulic pump 9 can be regulated, and preferably described pump is designed to two-way conveying.Therefore, oil hydraulic pump 9 can or be transported to first active line 11 or second active line 12 with hydraulic medium.Throughput direction according to oil hydraulic pump 9 is set can be set as to overtake or backward and travel.First controlling device 13 is used for regulator solution press pump 9.The controlling mechanism of described first controlling device 13 and oil hydraulic pump 9 self interacts.Equally, also be provided with second controlling device 14 that acts on oil hydraulic motor 10 self controlling mechanism.The uptake of described oil hydraulic motor 10 is adjustable equally.

The velocity ratio r (t) of static pressure gear unit is determined by the corresponding angle of revolution of having set of oil hydraulic pump 9 or oil hydraulic motor 10.

Be provided with electronic control unit 16 and set the angle of revolution of oil hydraulic pump 9 and oil hydraulic motor 10.Described electronic control unit 16 links to each other with first controlling device 13 by first control signal line 17.Electronic control unit 16 also links to each other with second controlling device 14 by second control signal line 18.Controlling device 13,14 comprises for example hydrovalve of passing ratio magnet control, and described hydrovalve can be set in the positioning pressure in the positional cylinder.

In described embodiment, electronic control unit 16 links to each other with CAN (control area net) bus 20 by connecting line 19.By described CAN bus 20, electronic control unit 16 receives accelerator pedal 22 position alpha _PedalInformation and fine motion pedal 23 position alpha _InchInformation.The CAN bus that is used for communicating between by the controller of the driver's operation of utility vehicle and electronic control unit 16 is construed as just example.Also can directly connect by several signaling lines.For the purpose of graphical illustration, another controlling rod 21 that is connected to equally on the CAN bus 20 illustrates as an example.For example, described controlling rod 21 can be used for promoting and reduces delivery and shovel.

In addition, transmission control device 25 links to each other with CAN bus 20 by another signal line 24.Described transmission control device 25 interacts by the ejecting system 27 of injection signal line 26 with diesel engine 2.The ejecting system 27 of diesel engine 2 comprises jet pump 28.Injection signal according to receiving by signaling line 26 sprays into definite emitted dose by jet pump 28 to described diesel engine 2.Therefore, the specific rotation speeds of diesel engine 2 is adjustable under the situation of the available output of satisfying the customer needs.

In following all methods, suppose that the rotating speed of setting in this way of diesel engine all can satisfy needed output, no matter be that hydraulic system of working or driving mechanism need, also or they unite needs.

Under the simple scenario of a pure operation of travelling, the driver has preset a specific acceleration expectation by handling accelerator pedal 22 for acceleration.The position alpha of described accelerator pedal 22 _PedalCan be at 0 degree and maximum position α _MaxBetween regulate.Therefore from vehicle stationary state, the accelerator pedal maximum position of being preset by the driver is a position alpha _MaxIt is corresponding to the maximum acceleration of expectation.If vehicle is static at first, then be adjusted to time per unit variation numerical value greatly by velocity ratio r (t) with static pressure gear unit 3, obtain the acceleration of maximum possible.

Determine based on following equation by the velocity ratio that electronic control unit 16 is realized:

$r_{\mathrm{soll}}(t+\mathrm{\Δt})=r_{\mathrm{soll}}\left(t\right)+\frac{d}{\mathrm{dt}}{r}_{\mathrm{soll}}\·\mathrm{\Δt}---\left(1\right).$

In described equation,

Expression velocity ratio variance ratio.So described velocity ratio variance ratio

Multiply by time lag Δ t and obtain a velocity ratio changing value, target velocity ratio r _Soll(t) based on driver's acceleration expectation and changed this velocity ratio changing value through time lag Δ t.At the fixed target gear ratio value r of time point (t+ Δ t) (t+ Δ t), electronic control unit 16 determines to be respectively applied for the desired angle of revolution of oil hydraulic pump 9 and oil hydraulic motor 10 based on thus.Thereby by first control signal line 17 or second control signal line 18 control signal of determining is imported first controlling device 13 or second controlling device 14 respectively.

The accelerator pedal position α that presets except the driver _PedalOutside, so-called " correction value " (allowance-making value) also is used for determining the velocity ratio variance ratio

Under the simplest situation that has comprised pure transmission mechanism control, described correction value is considered vehicle actual velocity v at that time _IstThereby, for having determined that by the 22 default acceleration expectations of compacting accelerator pedal is quickened an expectation eigenvalue (α by the driver _Pedal-α _{Pedal, grenz}), it comprises correction value α _{Pedal, grenz}With accelerator pedal position α _Pedal

Preferably, quickening the expectation eigenvalue is accelerator pedal position α _PedalWith correction value α _{Pedal, grenz}Between poor.Described correction value α _{Pedal, grenz}Be expressed as " limit pedal position " below, the pedal position value that described limit pedal position is a supposition.The velocity ratio variance ratio

Can determine according to following relation:

$\frac{d}{\mathrm{dt}}{r}_{\mathrm{soll}}{|}_{\min }\≤\frac{d}{\mathrm{dt}}{r}_{\mathrm{soll}}=m({\mathrm{\α}}_{\mathrm{Pedal}}-{\mathrm{\α}}_{\mathrm{Pedal},\mathrm{grenz}})\≤\frac{d}{\mathrm{dt}}{r}_{\mathrm{soll}}{|}_{\max }---\left(2\right).$

Because at correction value α _{Pedal, grenz}In considered current travelling speed v _Ist, therefore can be according to current driving speed, from possible maximum travelling speed v _MaxCome to determine the velocity ratio variance ratio in proportion

Can determine limit pedal position α by following relation _{Pedal, grenz}:

$0\≤{\mathrm{\α}}_{\mathrm{Pedal},\mathrm{grenz}}={\mathrm{\α}}_{\max }\frac{v_{\mathrm{fahr}}}{v_{\max }}\≤1---\left(3\right).$

Correction value it is also conceivable that other eigenvalues except those only depend on the eigenvalue of driving mechanism.Especially, it has considered other output requirement, for example, because hydraulic system of working produced.For this reason, the driver is by fine motion pedal 23, and which of default diesel engine 2 maximum available outputs partly is used for hydraulic system of working, do not illustrate among the figure, and which part is used for driving mechanism.Consider fine motion pedal position α _Inch, limit pedal position α _{Pedal, grenz}Can draw by following relation:

$0\≤{\mathrm{\α}}_{\mathrm{Pedal},\mathrm{grenz}}={\mathrm{\α}}_{\max }\frac{v_{\mathrm{fahr}}}{v_{\max }}+{\mathrm{c\α}}_{\mathrm{inch}}\≤1---\left(4\right)$

Before making a more detailed description by Fig. 3-6 pair of working method of the present invention, elder generation's procedural order is described in conjunction with the simple flow chart among Fig. 2.At first in step 30, determine the position alpha of accelerator pedal 22 _PedalIn the step 31 of this method, determine the actual velocity v of vehicle _IstIn addition, in step 32, determine as being used to calculate the velocity ratio variance ratio

Fine motion pedal 23 position alpha of another input value _InchBy actual velocity v _IstWith fine motion pedal position α _InchCalcuating correction value α _{Pedal, grenz}In step 34, calculate accelerated period and hope eigenvalue (α _Pedal-α _{Pedal, grenz}), and with limit pedal position α _{Pedal, grenz}As correction value.Also just calculate acceleration pedal position α for this reason _PedalWith correction value α _{Pedal, grenz}Between poor.In step 35, based on the acceleration expectation eigenvalue (α that in step 34, obtains _Pedal-α _{Pedal, grenz}) calculate the velocity ratio variance ratio

Except described acceleration expectation eigenvalue (α _Pedal-α _{Pedal, grenz}) outside, the velocity ratio variance ratio

Also comprise and be used to set up characteristic parameter m.Below with reference to Fig. 3 this is described further.

In step 35, determined the velocity ratio variance ratio

Afterwards, according to equation 1 by previous target gear ratio value r (t), velocity ratio variance ratio

Calculate a new target gear ratio value r with time lag Δ t _Soll(t+ Δ t).In step 37, oil hydraulic pump 9 and oil hydraulic motor 10 are adjusted to corresponding angle of revolution obtain target velocity ratio r _SollTherefore, in view of driver's acceleration expectation, change has taken place in travelling speed.Since the circulation of operation continuously, the travelling speed v after the change _IstBe used to calculate a new target velocity ratio again.

Process of the present invention allows irrespectively to set the rotating speed of diesel engine with acceleration, and allows to travel automatically during operation.It is how to velocity ratio r that Fig. 3 has described the present invention with chart _Soll(t) set.Directly draw each limit pedal position α from relation 2 _{Pedal, grenz}The straight line that all to have a gradient be m.

Under these circumstances, limit pedal position or correction value α _{Pedal, grenz}Determined the zero passage of straight line.Shown in the straight line among Fig. 3 42 like that.Like this, this specific straight line 42 presents with vehicle given travel speed v _IstCorrection value α for the basis _{Pedal, grenz}, specified limit pedal position just.According to relation 3, the increase of travelling speed will cause the increase of correction value, that is to say limit pedal position α _{Pedal, grenz}The characteristic curve of 43 expressions in Fig. 3 moves.In contrast, the reduction of travelling speed will cause characteristic curve to move towards the characteristic curve direction by 44 expressions.

In order to simplify, only use straight line characterization curve among Fig. 3.Yet, can realize other characteristic curve shape by parameter m is carried out suitable parametrization equally, it for example illustrates as characteristic curve 45.

Like this, determine the only velocity ratio variance ratio between fastest ratio variance ratio and maximum transmission ratio variance ratio along characteristic curve

Same consideration fine motion pedal position α _Inch, as shown in relation 4, can regulate individually by another parameter c.With fine motion pedal position α _InchTake into account, consider that just more output requires and other customer, hydraulic system of working for example, it has identical function, because they as the variation of travelling speed, are included in correction value α equally _{Pedal, grenz}In.This just means fine motion pedal position α _InchIncrease will cause the characteristic curve among Fig. 3 to move right.On the contrary, the pedal angle of fine motion pedal 23 reduce will cause limit pedal position α _{Pedal, grenz}Reduce, this is moved to the left corresponding to the characteristic curve among Fig. 3.

Illustrate different travelling states among Fig. 4-6.

At first, Fig. 4 shows accelerator pedal 22 and is set to angle [alpha] ₁Travelling state.Car speed v on this time point _IstStill relatively low, to such an extent as to characteristic curve 42 ' zero passage occurs in the place near pedal angle [alpha]=0 among the figure.Velocity ratio variance ratio and pedal angle [alpha] ₁Between relation show at a p ₁The place produces maximum possible velocity ratio variance ratio.

Therefore, for each time lag Δ t that scanning speed produced, velocity ratio r owing to the D/A converter of scanning accelerator pedal 22 and fine motion pedal 23 positions _Soll(t) increased the numerical value that shows by the maximum transmission ratio variance ratio.The vehicle acceleration that produces makes the actual velocity v of vehicle _IstIncrease.

As described in the explanation of Fig. 3, this is corresponding to the moving towards the arrow direction of characteristic curve 42 ' among Fig. 4.

In case characteristic curve 42 ' and expression maximum transmission ratio variance ratio

Straight line intersect at a P1 place, then determine the velocity ratio variance ratio by characteristic curve 42 '.

In Fig. 5, giving it the gun of before having shown is that the time point a little later illustrates.Because acceleration and associated speed v _IstIncrease, characteristic curve 42 ' moves right, thus by based on pedal position α ₁Some P2 determine the velocity ratio variance ratio

Process continues, the characteristic curve 42 ' value and the pedal position α of limit pedal position that move right in Fig. 5 ₁The point that overlaps.Therefore, quicken in the equation (2) the expectation eigenvalue become 0 and the velocity ratio r (t) of static pressure gear unit 3 no longer change.

More than about the description of moving of characteristic curve 42 ', will be used for the retraction of accelerator pedal 22 by the correction of necessity.In Fig. 5, for example show accelerator pedal position α ₂, it causes the fastest ratio variance ratio at a P3 place

On the other hand, the fine motion pedal position α that has comprised non-0 has been shown among Fig. 6 _InchConsideration, with the situation of Fig. 1 as starting point.Correction value α is considered in the position of fine motion pedal 23 _{Pedal, grenz}In, make and do not considering that the characteristic curve 42 ' under fine motion pedal 23 situations is moved, and forms new characteristic curve 46.Therefore, than the situation of Fig. 4, at accelerator pedal position α ₁The place, the velocity ratio variance ratio

Reduce, even under the situation of low speed driving.Because not every motor output all is specifically designed to driving mechanism, has therefore produced a less acceleration.

The advantage of method of the present invention is that accelerator pedal 22 is directly used in default acceleration.That is to say, show higher demand acceleration by the driver, that is, and accelerator pedal position α _PedalBig more, the velocity ratio variance ratio

Just big more, so the variation of each time lag velocity ratio is also just big more.On the contrary, fine motion pedal 23 pedal angle [alpha] _InchIncrease will make the velocity ratio variance ratio

Reduce.In described process, at each pedal position α _PedalAll there is a final velocity ratio in the place, and the velocity ratio r (t) of setting is approximately progressively near this final velocity ratio.By with parameter m, c parametrization, can be adapted to the transmission strategy of various requirement simply, for example the use condition of vehicle particularly.Especially, revise the characteristic of pedal in simple mode.

Above-mentioned method not only can be used for having the working machine of static pressure gear unit but also can be used for having the working machine of stepless variable output branch transmission system.

Claims (5)

1. a method of controlling the velocity ratio of stepless speed variator comprises the steps:

Detect accelerator pedal position (α _Pedal);

Detect actual travel speed (v _Ist);

By considering actual travel speed (v _Ist) and accelerator pedal position (α _Pedal) determine the velocity ratio variance ratio of stepless speed variator

Determine as actual transmission than (r _SollAnd the velocity ratio changing value (t))

The target gear ratio value of sum; With

Set the new gear ratio value (r of stepless speed variator _Soll(t+ Δ t)).

2. the method for claim 1 is characterized in that, in order to calculate the velocity ratio variance ratio

The time consider travelling speed (v _Ist), calculate the correction value (α comprise actual travel speed and the ratio of maximum travelling speed _{Pedal, grenz}).

3. method as claimed in claim 2 is characterized in that, in order to determine the velocity ratio variance ratio

By correction value (α _{Pedal, grenz}) and detected accelerator pedal position (α _Pedal) calculate and quicken the expectation eigenvalue.

4. method as claimed in claim 3 is characterized in that, quickens expectation eigenvalue (α in order to calculate _Pedal-α _{Pedal, grenz}), calculate detected accelerator pedal position (α _Pedal) and correction value (α _{Pedal, grenz}) between poor.

5. as each described method in the claim 2 to 4, it is characterized in that, at calcuating correction value (α _{Pedal, grenz}) time, except actual travel speed, consider that also another output requires (c α _Inch)

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