CN102141144B - Method for controlling three-parameter automatic speed changing of working vehicle - Google Patents

Abstract

The invention relates to a method for controlling three-parameter automatic speed changing of a working vehicle, belonging to the technical field of engineering machinery. In the method, throttle aperture, vehicle speed and working loading coefficient are taken as the parameters of automatic speed changing of the working vehicle; an all-condition optimal gear shifting distribution table is obtained according to different working condition off-line matching determined by the three different parameters; during real speed changing control, the optimal gear shifting point at an arbitrary working loading coefficient and an arbitrary throttle aperture is obtained by adopting an interpolation method according to eleven optimal speed changing characteristic curves; or the functional relationship among the optimal gear shifting point speed, the working loading coefficient and the throttle aperture is fitted directly according to the optimal gear shifting characteristic curves, and the functionis directly written in an automatic gear shifting controller to perform automatic speed changing control. By adopting the method provided by the invention, the transmission system loading fluctuationof the working vehicle is reduced, the fuel efficiency is improved, the service life of main components can be prolonged, the dynamic property and economical efficiency become better, the environmentpollution is reduced, and the method can be widely used for the automatic speed changing of self-propelled engineering vehicles, mining vehicles, farm-oriented vehicles and military vehicles.

Description

Working truck three parameter automatic shift control methods

Technical field

The invention belongs to technical field of engineering machinery, be specifically related to a kind of three parameter automatic shift control methods of working truck.

Background technique

The vehicle that the working truck general reference is travelled while working.Handle the driver of working truck except the needs steering vehicle travels, also need to operate numerous handles task that fulfils assignment, labor intensity is large, is easy to fatigue.Working truck is realized automatic speed changing, not only can alleviate driver's labor intensity, and main is to allow the driver that more attention is concentrated in the operation, improves operation quality and operating efficiency.For this reason since the eighties in last century, the automatic Transmissions Technique research of working truck is just taken in countries in the world, what use in working truck at first is VOLVO company, and then, the ZF company of Germany, the Ka Te company of the U.S., Kawasaki company, Komatsu, TCM Corp. of Japan have used the automatic transmission technology at working truck in succession.At present in the existing more application of working truck field automatic Transmissions Technique, but analyzing present working truck automatic Transmissions Technique can find out, they are to have continued to use automobile two parameters (throttle, the speed of a motor vehicle) automatic Transmissions Technique basically, only the operating mode with working truck simply is divided into " operation " and " not operation ", and has used respectively different gearshift curves.

In fact, during the working truck operation its operation power not right and wrong nothing is arranged, but at continually varying, and amplitude of variation is larger, will account for 60% of engine power such as the operation power amplitude of variation of loader.Obviously, simply to be divided into " operation " and " not operation " be irrational to the operating mode with working truck.Application practice also shows, used this automatic Transmissions Technique to compare with not using, and that the former transmission system load fluctuation becomes is large, fuel efficiency reduction, the main parts size lost of life, power character and Economy variation, environmental pollution also become large.

Summary of the invention

The objective of the invention is, consider working truck operating load characteristics continuous, that significantly change, provide a kind of working truck three parameter automatic shift control sides, to overcome the deficiency of present working truck automatic Transmissions Technique.

The present invention includes the following step:

1) with accelerator open degree α, speed of a motor vehicle v and operating load coefficient gamma as working truck self-shifting parameter, wherein: the operating load coefficient gamma is obtained by the following step:

Because apparatus for work uses hydraulic transmission, the working pump P of different purposes, different pressures usually ₁₁P _1m, P ₂₁P _2nBy fixing gear train G ₁₁G _1m, G ₂₁G _2nFrom the engine flywheel power taking,

1.1 for metering pump, as long as use pressure transducer S ₁₁S _1mDetect its outlet pressure, the engine flywheel torque that takies when calculating metering pump work:

M _1i＝K _1iP _1i

P in the formula _1iOutlet pressure for metering pump; COEFFICIENT K _1iObtain by Experimental Calibration, or calculate acquisition by following formula:

$K_{1i}=\frac{q_{1i}{i}_{1i}}{{2\mathrm{\π\η}}_{1i}}$

Wherein: q _1iBe quantitative pump delivery, i _1iBe the velocity ratio of flywheel shaft to quantitative pump shaft, η _1iBe the total transmission efficiency of metering pump;

1.2 for variable displacement pump, only need to use pressure transducer S ₂₁S _2nWith rotary angle transmitter A ₂₁A _2nMeasure its outlet pressure and variable angle, the engine flywheel torque that takies when calculating variable displacement pump work:

M _2i＝K _2iP _2itanβ _i

P in the formula _2iBe the variable displacement pump outlet pressure; β _iBe the variable angle; COEFFICIENT K _2iObtain by demarcating, or calculate acquisition by following formula:

K _2i＝125i _2id ²RZη _2i

Wherein: i _2iBe the velocity ratio from flywheel shaft to the variable pump shaft, d is the plunger diameter of variable displacement pump, and R is plunger central distribution circular diameter, and Z is the plunger number, η _2iBe the total transmission efficiency of variable displacement pump;

1.3 the operating load coefficient gamma is calculated by following formula:

$\mathrm{\γ}=k(\underset{i=1}{\overset{m}{\mathrm{\Σ}}}{M}_{1i}+\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{M}_{2i})/(\underset{i=1}{\overset{m}{\mathrm{\Σ}}}{M}_{1i\max }+\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{M}_{2i\max })$

In the formula: M _1iThe engine flywheel torque that takies when being i metering pump work; M _2iBe i the engine flywheel torque that variable displacement pump takies; M _1imaxWith M _2imaxBe each metering pump and each variable displacement pump shared engine flywheel torque when being operated in maximum load, k is a constant;

2) operating mode that determines for different accelerator open degree α, speed of a motor vehicle v and operating load coefficient gamma, the off-line coupling obtains the optimum gearshift of full operating mode distribution table, comprises the following steps:

2.1 get 11 kinds of operating load coefficient gamma values, be respectively 0,0.1,0.2 ..., 1.0, use formula M _L=γ M _LmaxCalculate the shared engine flywheel torque of operating load; M in the formula _LmaxThe total value of shared engine flywheel torque when being operated in maximum load for each metering pump and each variable displacement pump;

2.2 get accelerator open degree α be respectively 30%, 40%, 50% ..., 100%, the engine moment characteristic curve under every kind of accelerator open degree α is deducted M _L, obtain the engine net torque factor curve under each accelerator open degree α;

2.3 by obtaining to have 4 forward gears and 3 curve of traction characteristics that retreat gear after net torque characteristic and the power train coupling, and according to the principle of " automatic speed changing obtains optimum power character ", therefrom obtain optimum I-II gear, II-III gear, III-IV gear, and I'-II' gear, II'-III' keep off shifting points;

2.4 for each operating load coefficient gamma in the step 2.1, the optimum shifting points under the different accelerator open degree α in the step 2.2 and 2.3 is linked to be line, obtains the optimum speed change characteristic curve under this operating load coefficient gamma; For 11 kinds of listed in the step 2.1 operating load coefficient gamma values, 11 groups of so optimum speed change characteristic curves are arranged respectively, and write in the automatic gearshifting controller 10 with the form of the optimum gearshift of full operating mode distribution table;

3) when carrying out actual speed Control, according to 11 groups described in the step 2.4 optimum speed change characteristic curves, the optimum shifting points the when method of employing interpolation obtains any operating load coefficient gamma and any accelerator open degree α;

4) method of employing System Discrimination, according to optimum speed change characteristic curve, directly simulate the function relation of optimum shifting points speed and operating load coefficient gamma, accelerator open degree α, i.e. the optimum gearshift of full operating mode function, and this function write carry out automatic shift control in the automatic gearshifting controller 10.

In step 4) on the basis of described optimum shifting points speed, increase a speed increment Δ v, the speed sill value during as upshift, and reduce speed increment Δ v on the basis of the optimum shifting points speed of theory, as downshift spot speed sill value.

Adopt that the present invention can make that the transmission system load fluctuation of working truck diminishes, fuel efficiency raisings, main parts size life, power character and Economy improve and make the environmental pollution minimizing, the present invention can be widely used in the automatic speed changing of various self-propelled type engineering vehicles, mine vehicle, agri-vehicle, military vehicle.

Description of drawings

Fig. 1 is that working truck three parameters become the system architecture schematic diagram automatically

Motor when Fig. 2 is operating load coefficient gamma, accelerator open degree α and the common input characteristic curve of torque-converters

The curve of traction characteristics of the working truck when Fig. 3 is operating load coefficient gamma, accelerator open degree α

Optimum gear characteristic curve when Fig. 4 is the operating load coefficient gamma

Wherein: 1. the whole transmission 10. automatic shift control devices of motor 2. gas pedals 3. rotary angle transmitters 4. flywheels 5. fluid torque converters, 6. gearboxes, 7. vehicle speed sensor, 8. center differential 9. 11. gearshift control valves

P ₁₁P _1m--m metering pump; P ₂₁P _2n--n variable displacement pump; G ₁₁G _1m--metering pump is from the gear of flywheel power taking; G ₂₁G _2n--variable displacement pump is from the gear of flywheel power taking; S ₁₁S _1m--measure the sensor of metering pump outlet pressure; S ₂₁S _2n--the sensor of measurand pump discharge pressure; A ₂₁A _2n--the rotary angle transmitter at measurand pump variable angle; L ₁₁L _1m--by the apparatus for work of metering pump driving; L ₂₁L _2n--by the apparatus for work of variable displacement pump driving.

Embodiment

Below in conjunction with description of drawings embodiment

(1) system buildup

Shown in solid line among Fig. 1, suppose that the main transmission of certain working truck is by motor 1, fluid torque converter 5, gearbox 6, center differential 8, whole transmission 9 consist of, and wherein gearbox 6 has 4 forward gears (I, II, III, IV gear), and 3 retreat gear (I', II', III' gear).The transmission system of apparatus for work is by 1 gear quantitative pump B ₁₁, 1 plunger variable pump B ₂₁And the apparatus for work L that drives ₁₁, L ₂₁Form.

The sensor that automatic speed-changing system need to be installed comprises: with the rotary angle transmitter 3 that the rotating shaft of gas pedal 2 links to each other, vehicle speed sensor 7, the sensor S of metering pump outlet pressure ₁₁, variable displacement pump outlet pressure transducer S ₂₁And variable angle transducer A ₂₁

The analogue signal that each sensor records and pulse signal all are input in the automatic shift control device 10, and the gearshift control signal that automatic shift control device 10 sends passes to gearshift control valve 11 and finishes the gearshift action.

(2) operating load coefficient measuring and calculating method

1. calculate the engine flywheel torque that metering pump takies.If recording the outlet pressure value of metering pump is P ₁₁, the engine flywheel torque that takies when then metering pump is worked is calculated by following formula:

M ₁₁＝K ₁₁P ₁₁

Wherein: COEFFICIENT K ₁₁Obtain by demarcating; Or by calculating acquisition, its formula is

Q wherein ₁₁Be quantitative pump delivery, i ₁₁Be the velocity ratio of flywheel shaft to quantitative pump shaft, η ₁₁Be the total transmission efficiency of metering pump.

2. calculate the engine flywheel torque that variable displacement pump takies.If the variable displacement pump outlet pressure value that records is P ₂₁, the variable angle is β ₁, then the engine output torque that takies of variable displacement pump can be calculated by following formula:

M ₂₁＝K ₂₁P ₂₁tanβ ₁

Wherein: COEFFICIENT K ₂₁Obtain by demarcating; Or by calculating acquisition, its formula is K ₂₁=125i ₂₁d ²RZ η ₂₁, i wherein ₂₁Be the velocity ratio from flywheel shaft to the variable pump shaft, d is the plunger diameter of variable displacement pump, and R is plunger central distribution circular diameter, and Z is the plunger number, η ₂₁Be the total transmission efficiency of variable displacement pump.

3. operating load coefficient calculations.

Define the formula that is calculated as follows of operation loading coefficient, its value is between 0～1.

$\mathrm{\γ}=\frac{M_L}{M_{L\max }}$

Wherein: M _Lmax=M _11max+ M _21maxThe engine flywheel torque that takies during for maximum operation load;

M _L=M ₁₁+ M ₂₁The engine flywheel torque that takies during for current operating load.

(3) draw the automatic speed changing characteristic curve

1. get the operating load coefficient gamma and be respectively 0,0.1,0.2 ..., 1.0, use formula M _L=γ M _LmaxCalculate the shared engine flywheel torque of operating load.And do respectively following work 2..

2. getting accelerator open degree α is respectively 30%(and is made as throttle at idle), 40%, 50% ..., 100%, as shown in Figure 2, the engine moment characteristic curve under every kind of accelerator open degree α is deducted M _L, carry out again power train coupling, obtain at last as shown in Figure 3 have 4 forward gears and 3 curve of traction characteristics that retreat gear, and according to the principle of " automatic speed changing obtains optimum power character ", therefrom obtain optimum I-II gear shifting points P _I-II, optimum II-III gear shifting points P _II-III, optimum III-IV gear shifting points P _III-IV, and optimum I'-II' gear shifting points P _I'-II', optimum II'-III' gear shifting points P _II'-III'

3. for each operating load coefficient gamma in 1., the optimum shifting points under the different accelerator open degree α in 2. is linked to be line, shown in dot and dash line among Fig. 4, it is the optimum speed change characteristic curve under this operating load coefficient gamma.For in 1. listed 11 kinds _γValue has respectively 11 groups of such curves.Convenience during for working control must be able to be obtained the optimum speed change characteristic curve under any γ value.When carrying out actual speed Control, the optimum shifting points in the time of can adopting the method for interpolation to obtain any γ and any accelerator open degree α according to these 11 curves.In addition, can also adopt the method for System Discrimination directly to simulate optimum shifting points speed and γ according to these 11 curves, the function relation of α, and will carry out automatic shift control in this function writing controller.

4. in order to prevent the gearshift circulation, be raised to the speed of high gear from low gear and usually adopt different numerical value from the speed that reduces gear from high gear.In actual automatic shift control process, the basis of the shifting points speed of the theory that can 3. calculate in the upper step increases a speed increment Δ v, speed sill value during as upshift, with reduce Δ v on the basis of the shifting points speed of theory, as downshift spot speed sill value, avoid the gearshift circulation.Upshift characteristic curve during the operating load coefficient gamma made by theoretical shifting points curve, downshift characteristic curve are shown in heavy line and dotted line among Fig. 4.

(4) automatic speed changing working procedure is described

When adopting digital controller to carry out automatic shift control, at first when each sampling period arrives, measure respectively accelerator open degree α, the numerical value of speed of a motor vehicle v and operating load coefficient gamma.Then according to the operating load coefficient gamma that records and accelerator open degree α value, obtain the upshift speed of a motor vehicle and the downshift speed of a motor vehicle of current shift according to the method for introducing in front (3), if current vehicle speed is not top gear greater than the upshift speed of a motor vehicle and when front then rises one grade, if current vehicle speed less than the downshift speed of a motor vehicle and when front be not low gear, one gear then falls, in addition, then needn't shift gears.

Three parameter automatic Transmissions Technique provided by the present invention, because having taken into full account continuous, the significant impact that changes optimum gear characteristic of operating load, compare with existing working truck automatic Transmissions Technique, can effectively reduce the load fluctuation of transmission system, the power character of improve fuel efficiency and main parts size life-span, improving vehicle preferably and Economy, and effective minimizing environmental pollution.

The present invention includes the following step:

1) with speed of a motor vehicle v, accelerator open degree α and operating load coefficient gamma as working truck self-shifting parameter; Wherein: speed of a motor vehicle v can measure by vehicle speed sensor 7, and it is loaded on the gearbox 6, mostly is pulse signal; The measurement of accelerator open degree α can obtain by the corner of measuring door pedal 2 with gyration sensor 3.The operating load coefficient gamma is the parameter that can weigh the operating load size, is obtained by the following step:

Because apparatus for work uses hydraulic transmission, the working pump P of different purposes, different pressures usually ₁₁P _1m, P ₂₁P _2nBy fixing gear train G ₁₁G _1m, G ₂₁G _2nFrom the engine flywheel power taking,

1.1 for metering pump, as long as use pressure transducer S ₁₁S _1mDetect its outlet pressure, the engine flywheel torque that takies when calculating metering pump work:

M _1i＝K _1iP _1i

COEFFICIENT K in the formula _1iObtain by Experimental Calibration, or calculate acquisition by following formula:

$K_{1i}=\frac{q_{1i}{i}_{1i}}{{2\mathrm{\π\η}}_{1i}}$

Wherein: i=1,2 ..., m is the number of metering pump, q _1iBe quantitative pump delivery, i _1iBe the velocity ratio of flywheel shaft to quantitative pump shaft, η _1iBe the total transmission efficiency of metering pump;

1.2 for variable displacement pump, only need to use pressure transducer S ₂₁S _2nWith rotary angle transmitter A ₂₁A _2nMeasure its mouth pressure and variable angle, the engine flywheel torque that takies when calculating variable displacement pump work:

M _2i＝K _2iP _2itanβi

COEFFICIENT K in the formula _2iObtain by demarcating, or calculate acquisition by following formula:

K _2i＝125i _2id ²RZη _2i

Wherein: i=1,2 ... n is the number of variable displacement pump, i _2iBe the velocity ratio from flywheel shaft to the variable pump shaft, d is the plunger diameter of variable displacement pump, and R is plunger central distribution circular diameter, and Z is the plunger number, η _2iBe the total transmission efficiency of variable displacement pump;

1.3 the operating load coefficient gamma is calculated by following formula:

$\mathrm{\γ}=k(\underset{i=1}{\overset{m}{\mathrm{\Σ}}}{M}_{1i}+\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{M}_{2i})/(\underset{i=1}{\overset{m}{\mathrm{\Σ}}}{M}_{1i\max }+\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{M}_{2i\max })$

In the formula: M _1iThe engine flywheel torque that takies when being i metering pump work; M _2iBe i the engine flywheel torque that variable displacement pump takies; M _1imaxWith M _2imaxBe each metering pump and each variable displacement pump shared engine flywheel torque when being operated in maximum load, k is a constant;

2) operating mode that determines for different accelerator open degree α, speed of a motor vehicle v and operating load coefficient gamma, the off-line coupling obtains the optimum gearshift of full operating mode distribution table, comprises the following steps:

2.1 get 11 kinds of operating load coefficient gamma values, be respectively 0,0.1,0.2 ..., 1.0, use formula M _L=γ M _LmaxCalculate motor and overcome the flywheel moment that operating load consumes;

2.2 get accelerator open degree α be respectively 30%, 40%, 50% ..., 100%, the engine moment characteristic curve under every kind of accelerator open degree α is deducted M _L, obtain motor under each accelerator open degree α and be used for the net torque characteristic curve that travels;

2.3 by obtaining to have 4 forward gears and 3 curve of traction characteristics that retreat gear after net torque characteristic and the power train coupling, and according to the principle of " automatic speed changing obtains optimum power character ", therefrom obtain optimum I-II gear, II-III gear, III-IV gear, and I'-II' gear, II'-III' keep off shifting points;

2.4 for each operating load coefficient gamma in the step 2.1, the optimum shifting points under the different accelerator open degree α in the step 2.2 and 2.3 is linked to be line, obtains the optimum speed change characteristic curve under this operating load coefficient gamma; For 11 kinds of listed in the step 2.1 operating load coefficient gamma values, 11 groups of so optimum speed change characteristic curves are arranged respectively, because using microprocessor to mate online relatively difficulty of the optimum shifting points of calculative determination, we can reach the operating mode that " operating load coefficient " determines for different throttles, the speed of a motor vehicle, the off-line coupling obtains full operating mode most optimal gear distribution table, writes self shifter and controls in 10 devices;

3) when carrying out actual speed Control, according to 11 groups described in the step 2.4 optimum speed change characteristic curves, the optimum shifting points the when method of employing interpolation obtains any operating load coefficient gamma and any accelerator open degree α;

4) adopt the method for System Discrimination, according to optimum speed change characteristic curve, offline simulation goes out optimum shifting points speed and operating load coefficient gamma, the function relation of accelerator open degree α, and this function write carry out automatic shift control in the automatic gearshifting controller 10.

In order to prevent the gearshift circulation, be raised to the speed of high gear from low gear and usually adopt different numerical value from the speed that reduces gear from high gear.Working truck three parameter automatic shift control methods, on the basis of optimum shifting points speed, increase a speed increment Δ v, the speed sill value during as upshift, and at the basis of the optimum shifting points speed of theory minimizing speed increment Δ v, as downshift spot speed sill value.

Three parameter automatic Transmissions Technique provided by the present invention, because having taken into full account continuous, the significant impact that changes optimum gear characteristic of operating load, compare with existing working truck automatic Transmissions Technique, can effectively reduce the load fluctuation of transmission system, the power character of improve fuel efficiency and main parts size life-span, improving vehicle preferably and Economy, and effective minimizing environmental pollution.

Claims (2)

1. working truck three parameter automatic shift control methods is characterized in that comprising the following steps:

1) with accelerator open degree (α), the speed of a motor vehicle (v) and operating load coefficient (γ) as working truck self-shifting parameter, wherein: operating load coefficient (γ) is obtained by the following step:

Because apparatus for work uses hydraulic transmission, the working pump (P of different purposes, different pressures usually ₁₁P _1m, P ₂₁P _2n) by fixing gear train (G ₁₁G _1m, G ₂₁G _2n) from the engine flywheel power taking,

1.1 for metering pump, as long as use pressure transducer (S ₁₁S _1m) detect its outlet pressure, the engine flywheel torque that takies when calculating metering pump work:

M _1i＝K _1iP _1i

P in the formula _1iOutlet pressure for metering pump; COEFFICIENT K _1iObtain by Experimental Calibration, or calculate acquisition by following formula:

$K_{1i}=\frac{q_{1i}{i}_{1i}}{{2\mathrm{\π\η}}_{1i}}$

Wherein: q _1iBe quantitative pump delivery, i _1iBe the velocity ratio of flywheel shaft to quantitative pump shaft, η _1iBe the total transmission efficiency of metering pump;

1.2 for variable displacement pump, only need with pressure transducer (S ₂₁S _2n) and rotary angle transmitter (A ₂₁A _2n) measure its outlet pressure and variable angle, the engine flywheel torque that takies when calculating variable displacement pump work:

M _2i＝K _2iP _2itanβ _i

P in the formula _2iBe the variable displacement pump outlet pressure; β _iBe the variable angle; COEFFICIENT K _2iObtain by demarcating, or calculate acquisition by following formula:

K _2i＝125i _2id ²RZη _2i

Wherein: i _2iBe the velocity ratio from flywheel shaft to the variable pump shaft, d is the plunger diameter of variable displacement pump, and R is plunger central distribution circular diameter, and Z is the plunger number, η _2iBe the total transmission efficiency of variable displacement pump;

1.3 operating load coefficient (γ) calculates by following formula:

$\mathrm{\γ}=k(\underset{i=1}{\overset{m}{\mathrm{\Σ}}}{M}_{1i}+\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{M}_{2i})/(\underset{i=1}{\overset{m}{\mathrm{\Σ}}}{M}_{1i\max }+\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{M}_{2i\max })$

In the formula: M _1iThe engine flywheel torque that takies when being i metering pump work; M _2iBe i the engine flywheel torque that variable displacement pump takies; M _1imaxWith M _2imaxBe each metering pump and each variable displacement pump shared engine flywheel torque when being operated in maximum load, k is a constant;

2) operating mode that determines for different accelerator open degrees (α), the speed of a motor vehicle (v) and operating load coefficient (γ), the off-line coupling obtains the optimum gearshift of full operating mode distribution table, comprises the following steps:

2.1 get 11 kinds of operating load coefficients (γ) value, be respectively 0,0.1,0.2 ..., 1.0, use formula M _L=γ M _LmaxCalculate the shared engine flywheel torque of operating load; M in the formula _LmaxShared engine flywheel torque during for maximum operation load;

2.2 get accelerator open degree (α) be respectively 30%, 40%, 50% ..., 100%, the engine moment characteristic curve under every kind of accelerator open degree (α) is deducted M _L, obtain the engine net torque factor curve under each accelerator open degree (α);

2.3 by obtaining to have 4 forward gears and 3 curve of traction characteristics that retreat gear after net torque characteristic and the power train coupling, and according to the principle of " automatic speed changing obtains optimum power character ", therefrom obtain optimum I-II gear, II-III gear, III-IV gear, and I'-II' gear, II'-III' keep off shifting points;

2.4 for each operating load coefficient (γ) in the step 2.1, the optimum shifting points under the different accelerator open degrees (α) in the step 2.2 and 2.3 is linked to be line, obtains the optimum speed change characteristic curve under this operating load coefficient (γ); 11 kinds of operating load coefficients (γ) value for listed in the step 2.1 has respectively 11 groups of so optimum speed change characteristic curves, and writes in the automatic gearshifting controller (10) with the form of the optimum gearshift of full operating mode distribution table;

3) when carrying out actual speed Control, according to 11 groups described in the step 2.4 optimum speed change characteristic curves, the optimum shifting points the when method of employing interpolation obtains any operating load coefficient (γ) and any accelerator open degree (α);

4) method of employing System Discrimination, according to optimum speed change characteristic curve, directly simulate the function relation of optimum shifting points speed and operating load coefficient (γ), accelerator open degree (α), be the optimum gearshift of full operating mode function, and this function write in the automatic gearshifting controller (10) carry out automatic shift control.

2. by working truck three parameter automatic shift control methods claimed in claim 1, it is characterized in that in step 4) on the basis of described optimum shifting points speed, increase a speed increment (Δ v), speed sill value during as upshift, and reduce speed increment (Δ v) on the basis of the optimum shifting points speed of theory, as downshift spot speed sill value.

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