Method for optimizing a control map of a powertrain of a vehicle

Abstract

Method for controlling a drive train of a vehicle, wherein the drive train has a drive motor and a continuously variable transmission, each of which is controlled by a control map, wherein the control map has been determined by a method for optimizing (100) the control map of the drive train of the vehicle, wherein the method for optimizing (100) the control map has at least the following steps: - determining (10, 110) a transmission efficiency map; - determining (102) an engine consumption map; - Determining an energy consumption map as a function of different speeds of the drive motor at different driving speeds of the vehicle on the basis of the transmission efficiency map and the engine consumption map; - Determining a speed characteristic of the drive motor which corresponds to the lowest energy consumption depending on the driving speed, on the basis of the determined energy consumption map; - Determining (158) the control characteristic map as a function of the speed-dependent speed characteristic curve and corresponding gear ratios of the transmission, characterized in that the control of the drive motor and the continuously variable transmission is only carried out with the control characteristic map after the drive train has been operated for a minimum period at a specific operating point.

Description

[0001] The present invention relates to a method for optimizing a control map of a vehicle's drivetrain, which takes into account both the transmission efficiency of a continuously variable transmission and the engine efficiency. The invention also relates to a method for controlling a vehicle's drivetrain and to a computer program product. State of the art

[0002] Vehicle drive motors typically operate more efficiently at lower speeds. For example, in an internal combustion engine, fuel consumption normally increases proportionally with the engine speed. If a vehicle has a continuously variable transmission, the engine speed is usually kept as low as possible to minimize fuel consumption. At higher speeds, for example, a variator of the continuously variable transmission is first adjusted, and then the range is changed at the end of a driving range to keep the engine speed low. There may also be an engine characteristic curve that specifies consumption-optimized operating points for the drive motor.

[0003] However, such a continuously variable transmission also has an operating-point-dependent efficiency. If the transmission is used at an unfavorable operating point, energy consumption may be increased. Furthermore, the efficiency of a drive motor is often highly load-dependent. Therefore, in a partial-load range, the efficiency of the combustion engine may be low, or at least different, than in the full-load range. Furthermore, a different operating point of the drive motor may be more efficient in a partial-load range than in a full-load range.

[0004] Likewise, a transmission can be controlled according to its efficiency curve over a driving speed. For example, an envelope curve is created to achieve optimal transmission efficiency and to maintain the transmission within the thus-created range, for example by controlling a variator and, alternatively or additionally, adjusting the respective shift elements to change driving ranges. However, since the engine operating point and a transmission operating point are mutually dependent, vehicles are operated either with an optimized engine strategy or an optimized transmission strategy. Since the influence of the drive engine on efficiency is normally greater, priority is usually given to optimizing the engine control.

[0005] DE 42 23 967 A1 describes a device for adjusting a transmission output torque or a transmission output power in vehicles with a continuously variable transmission (CVT).

[0006] DE 10 2017 113 253 A1 describes a control strategy for reducing fuel consumption in a machine. It also describes a powertrain system that implements this control strategy.

[0007] WO 98 / 54022A1 describes a control system which selects the gear ratio within a range of possible gear ratio values in such a way that the greatest possible overall efficiency is achieved by jointly taking into account the individual efficiency functions of a vehicle drive and the respective auxiliary units including their drive.

[0008] DE 10 2018 201 035 A1 describes a speed control method for controlling the speed of an internal combustion engine of a work machine that is mechanically coupled to a continuously variable transmission.

[0009] DE 10 2008 038 095 A1 describes a control unit which is designed, at least in one operating mode, to specify a target speed range and / or a target torque range.

[0010] DE 28 11 574 A1 describes a device for controlling a drive motor-gearbox unit of a motor vehicle.

[0011] DE 10 2011 089 607 B4 describes a method for operating a serial hydraulic hybrid drive system. Description of the invention

[0012] A first aspect relates to a method for optimizing a control map of a drive train of a vehicle. The drive train has a drive motor and a continuously variable transmission. The control map can be stored, for example, in a control unit of the drive train. Using the control map, an engine speed and a gear ratio of the drive transmission can be set, for example, depending on a desired driving speed and optionally a required drive power or output power. The drive motor can be designed, for example, as a traction motor. The drive motor can be designed, for example, as an internal combustion engine or electric machine. The continuously variable transmission can be designed to transmit drive power from the drive motor to an output.The gear ratio can result from the control of a variator of the continuously variable transmission and, alternatively or additionally, a driving range of the transmission. The variator can, for example, be designed as a hydrostatic transmission, in which a variable displacement pump is pivoted by the control. The driving range can, for example, be changed by switching a planetary assembly of the continuously variable transmission. The drive train can provide driving power for driving the vehicle. Alternatively or additionally, the drive train can provide power for using a tool of the vehicle. Alternatively or additionally, the drive train can drive respective auxiliary consumers, such as a power take-off shaft, a hydraulic pump for a hydraulic steering unit, a hydraulic pump for lubricating the transmission and, alternatively or additionally, a fan. The vehicle can, for example, be designed as a work machine.The work machine can be designed, for example, as an agricultural machine or construction machine. An example of an agricultural machine is a tractor. The continuously variable transmission can, for example, have an electric or hydraulic variator. The continuously variable transmission can, for example, be designed as a power-split transmission. A continuously variable transmission can, for example, be a transmission in which a gear ratio is continuously adjustable within a specific gear ratio range. The continuously variable transmission can, for example, be designed as a CVT transmission or IVT transmission.

[0013] The method includes a step of determining a transmission efficiency map. The transmission efficiency map can be speed-dependent and output power-dependent. For example, a speed-dependent transmission efficiency curve can be determined for each output power. The determination can also be performed for discrete output powers and, alternatively or additionally, discrete output speeds. In real-world use, interpolation can then take place, for example, between the transmission efficiency curves. The transmission efficiency map can be determined experimentally on a test bench, for example, for each individual vehicle or for all vehicles in a series.

[0014] Alternatively, the transmission efficiency map can also be determined using a calculation such as a simulation. For this purpose, a transmission structure can be entered, for example. The transmission structure can have a so-called shaft code. Alternatively or additionally, the transmission structure can have a shift matrix, the types of shift elements, a type of variator, and possible gear ratios. Linear systems of equations for the transmission can then be solved to determine ideal speeds. Alternatively or additionally, linear systems of equations for the transmission can be solved to determine ideal torques. In addition, required torques can be restricted, for example to take into account restrictions on the possible tractive force due to physical limits of the drive train at low travel speeds. On this basis, torque loss calculations for the respective components of the transmission can be carried out.The lost torques can be speed-dependent, power-independent, or power-dependent. On this basis, a linear system of equations can be solved to determine all lost torques. The power loss of the drive transmission can be calculated based on the lost torques. In addition, the transmission efficiency can be calculated using the ratio of supplied power, which can correspond to the input power, to output power, which can correspond to the output power. These steps can be performed for all possible gear ratios or operating points of the variator. These steps can be performed for all possible driving ranges of the drive transmission. These steps can be performed for all possible or desired transmission input speeds. These steps can be performed for all possible or desired transmission output powers.This can then be used to determine the transmission efficiency map, which, for example, has a family of speed-dependent transmission efficiency curves, optionally at different load conditions.

[0015] The method includes a step of determining an engine consumption map. The engine consumption map can be provided, for example, by an engine manufacturer. The engine consumption map can be determined, for example, analogously to the transmission efficiency map, on a test bench or by means of a simulation. The engine consumption map can, for example, comprise a family of speed-dependent engine consumption curves, optionally at different load conditions.

[0016] The method includes a step of determining an energy consumption map as a function of different engine speeds at different vehicle speeds based on the transmission efficiency map and the engine consumption map. The energy consumption map can, for example, comprise a set of speed-dependent energy consumption curves, optionally at different load conditions. This allows the overall efficiency of the drive train to be taken into account. For example, at certain operating points, it may be more efficient to operate the drive train with a lower engine efficiency but a better transmission efficiency. Optimization is then possible, taking into account the efficiency of the drive motor and the transmission.

[0017] The method includes a step of determining a speed characteristic curve of the drive motor, which corresponds to the lowest energy consumption depending on the driving speed, based on the determined energy consumption map. The energy consumption can, for example, correspond to the fuel consumption of the drive motor or the power consumption of the drive train, for example, per 100 km of driving distance. The speed characteristic curve thus indicates which speed of the drive motor leads to the lowest energy consumption at a certain desired driving speed. A speed characteristic curve can also be determined for each drive power. This will be explained below.

[0018] The method comprises a step of determining the control characteristic map as a function of the driving speed-dependent speed characteristic curve and the corresponding gear ratios of the driving transmission. Multiple speed characteristic curves can also be taken into account when determining the control characteristic map. The control characteristic map can, for example, correspond to the operating point of the drive train at each driving speed and optionally at different drive powers, which results in the lowest energy consumption. For an energy consumption characteristic map, the control characteristic map can, for example, correspond to the lowest edge of a family of characteristics. The corresponding gear ratio of the driving transmission can, for example, be determined directly mathematically from the desired driving speed and the associated energy-consumption-optimized speed of the drive motor.The gear ratio of the transmission can determine a driving range and a position of a variator.

[0019] In one embodiment of the method, the step of determining the energy consumption map as a function of different engine speeds at different vehicle speeds also occurs at different drive powers for each driving speed. Thus, a family of driving speed-dependent energy consumption curves can be determined, with each energy consumption curve being assigned to a drive power. For example, energy consumption curves for drive powers can be determined at discrete intervals. Interpolation can be performed between these two steps, for example, either to determine the energy consumption map or, alternatively or additionally, also during the actual control.The speed characteristic of the drive motor, which corresponds to the lowest energy consumption depending on the driving speed, is determined for the different drive powers in order to generate a speed characteristic field for the drive motor that corresponds to the lowest energy consumption depending on the driving speed and drive power. A family of driving speed-dependent speed characteristic curves of the drive motor can therefore be determined, with one speed characteristic from each of the family of speed characteristic curves corresponding to the lowest energy consumption at a specific drive power. Here, too, interpolation between characteristic curves is possible, for example. The control characteristic field is determined depending on the driving speed-dependent and drive power-dependent speed characteristic field and a corresponding transmission ratio of the drive transmission.This allows the energy-minimizing engine speed and gear ratio to be specified for each driving speed at different drive power levels. This also allows for the fact that in a partial load range, the efficiency of the drive motor is less relevant than the efficiency of the transmission.

[0020] In one embodiment of the method, the different drive powers are calculated as a function of the output power and the transmission efficiency map. This allows for consideration of the fact that the transmission efficiency influences how much drive power must be provided by the drive motor to provide the desired output power.

[0021] In one embodiment of the method, it is provided that the different drive powers are calculated depending on a speed-dependent power consumption of auxiliary consumers. For example, a necessary drive power can result from a desired output power and the power requirement of auxiliary consumers. For example, at a certain driving speed, more power must be made available by the drive engine when an auxiliary consumer is activated than when this auxiliary consumer is deactivated. For example, an auxiliary consumer can drive a tool, operate a ventilation system, or drive a power take-off shaft with an attachment. Control maps can also be determined separately for each state of auxiliary consumers. Each control map can then be determined depending on different states of the respective auxiliary consumer.The drivetrain control, i.e., the engine speed and gear ratio, can then be adjusted depending on the state of the auxiliary consumers. For example, at a certain driving speed with a certain drive power and activated ventilation, a higher engine speed and lower gear ratio may be optimal for energy consumption than at the same driving speed with the same drive power and deactivated ventilation.

[0022] In one embodiment of the method, it is provided that when determining respective speed characteristics of the drive motor which correspond to the lowest energy consumption depending on the driving speed, respective operating points are truncated due to a speed-dependent maximum power of the drive motor being exceeded. For example, the drive motor cannot generate more than the maximum power without damage, excessive wear, or even physically at all. Corresponding control is therefore undesirable, even if the drive train would theoretically operate more efficiently here. Such operating points are therefore no longer taken into account during optimization. For example, truncation can cause respective speed characteristics to end when the maximum power of the drive motor is reached. This allows corresponding boundary conditions to be taken into account.

[0023] In one embodiment of the method, it is provided that when determining respective speed characteristics of the drive motor, which correspond to the lowest energy consumption depending on the driving speed, respective operating points are cut off due to speed restrictions during operation of the work machine. For example, operation of the work machine requires that the drive motor always rotate at a minimum speed. For example, the input speed of the drive transmission may have a minimum value due to the required volume flows of the lubrication pumps. However, there may also be maximum speeds, exceeding which could lead to damage or be undesirable due to excessive wear. Corresponding control is therefore not desired, even if the drive train would theoretically operate more efficiently here. Such operating points are therefore not further taken into account during optimization.By truncating, the respective speed characteristic curves can end when the speed limits are reached. This allows the corresponding boundary conditions to be taken into account.

[0024] In one embodiment of the method, it is provided that the method further comprises a step of storing the control map on a data storage device. The data storage device can, for example, comprise a volatile or non-volatile memory module. For example, the data storage device can be designed as a hard disk or CD. The control map can be stored as part of a computer program product. The computer program product can, for example, be designed to control the speed of the drive motor and the gear ratio of the drive transmission in a consumption-optimized manner when executed on the control unit of the drive train. The method can comprise a step of loading the control map into a control unit of the drive train of the vehicle. The control map can be transferred to a data storage device of the control unit. The control unit can, for example, comprise a microcontroller.

[0025] A second aspect relates to a method for controlling a drive train of a vehicle. The drive train has a drive motor and a continuously variable transmission. The drive motor and the continuously variable transmission are controlled using a control map determined according to the method according to the first aspect. As a result, fuel consumption can be optimized system-wide, optionally also taking into account a load state of the drive train. Respective advantages and further features can be found in the description of the first aspect, with embodiments of the first aspect also forming embodiments of the second aspect, and vice versa.

[0026] According to the invention, the control of the drive motor and the continuously variable transmission is only carried out using the control map after the drive train has been operated at a specific operating point for a minimum period. With conventional control of the drive train, the engine speed remains virtually constant when the vehicle's speed changes, and it is mainly the transmission ratio that changes continuously in proportion to the driving speed. With the control map optimized here, however, the engine speed can fluctuate with the driving speed and, alternatively or additionally, the transmission ratio can also fluctuate. In order to avoid unusual operating behavior or frequent speed changes of the drive motor that could result in losses, the system therefore only switches to consumption-optimized control when the vehicle remains in one operating state for a long time.The operating state can, for example, include a drive power and, alternatively or additionally, a driving speed. An operating state can also be defined by a maximum deviation from an operating point.

[0027] A third aspect relates to a computer program product having a control map generated using a method according to the first aspect. The computer program product can be configured to be executed on a control unit of the drive train for carrying out the method according to the second aspect. The computer program product can contain program code by means of which the drive train can be controlled. Respective advantages and further features can be found in the description of the first and second aspects, respectively, wherein embodiments of the first and second aspects also form embodiments of the third aspect, and vice versa. Short description of the characters Fig. 1 schematically illustrates a method for determining a transmission efficiency map. Fig. 2 schematically illustrates a method for optimizing a control map of a drive train of a vehicle, wherein the drive train has a drive motor and a continuously variable transmission. Fig. 3 schematically illustrates a method according to Fig. 2 generated optimized control map of the powertrain. Detailed description of embodiments

[0028] Fig. Figure 1 schematically illustrates a method for determining a transmission efficiency map of a continuously variable transmission of a vehicle with a drive motor. The method begins with step 10. In a subsequent step 12, a transmission structure is read in. This reading in step 12 includes reading in step 14 of a shaft code, reading in step 16 of a shift matrix, reading in step 18 of the respective types of shift elements, reading in step 20 of a variator type of the transmission, and reading in step 22 of the possible transmission ratios. This information is collected in step 24.

[0029] A subsequent step 26 begins the calculation of a transmission efficiency curve as a function of speed. The speed is the input speed or output speed of the transmission. In this calculation, the respective speeds of all transmission components are calculated in step 28. The respective torques of all transmission components are calculated in step 30. The respective tractive force limits are taken into account as boundary conditions in step 32. For this purpose, the tractive force is calculated in step 34. This is dependent on the vehicle weight determined in step 36, the friction coefficient determined in step 38, the output power determined in step 40, the tire diameter determined in step 42, and the axle ratio determined in step 44. In step 46, the calculation is based on an operating point of the drive train.In step 48, load-dependent and speed-dependent torque losses in the transmission are determined. Additional design features of the transmission are taken into account as input variables. These include the seals 50, the shift elements 52, the bearings 54, the gears 56, the respective system pumps 58, a variator 60 of the transmission, and the respective brakes 62 of the transmission. This calculation is performed as a loop for all variator ratios in a driving range, as illustrated in step 64. After completing the calculation for the variator ratios in one driving range, the calculation is performed again with the loop of the variator ratios in another driving range. This calculation for all driving ranges is illustrated in step 66. After completing these calculations, a transmission efficiency characteristic curve is generated, as illustrated in step 68.

[0030] This calculation of the transmission efficiency curve according to step 26 is repeated for all input speeds of the transmission that correspond to the speed of the drive motor. This loop is illustrated by step 70. For example, between speeds of 1300 and 2100, the loop is run through in speed steps of 100 or 10. This loop according to step 70 is repeated for all output powers of the drive train, which is illustrated by step 72. For example, between output powers of 1% and 100%, the loop is run through in output power steps of 10% or 1%. The loops can be run through in discrete steps by changing the corresponding value. After all loops have been completed, the transmission efficiency map is created in step 74. This procedure can be more cost-effective than determining it on a test bench.With smaller steps in the value variation in the loops, the transmission efficiency map can be more precise and contain more information. With larger steps, the calculation is faster and can, for example, be performed online by the powertrain control unit to optimize powertrain control depending on the driving situation. The transmission efficiency map makes it possible to make a statement about transmission efficiency at different input speeds of the drive transmission, different output powers, and different vehicle speeds.

[0031] Fig. Figure 2 schematically illustrates a method for optimizing a control map of a drive train of a vehicle, wherein the drive train has a drive motor and a continuously variable transmission. The method starts in step 100. In step 102, an engine consumption map is determined. The engine consumption map allows a statement to be made about the energy consumption of the drive motor at a certain engine speed and engine load. The engine consumption map can be requested, for example, from the manufacturer of the drive motor. In step 104, a power and torque characteristic curve of the drive motor is read in. In step 106, a transmission efficiency map is read in. This can either be determined on a test bench, as illustrated by step 108, or, as illustrated by step 110, using the method according to Fig. 1. In a step 112, speed restrictions of the drive motor are read in. Thus, when determining respective speed characteristics of the drive motor, which correspond to the lowest energy consumption depending on the driving speed, respective operating points can be truncated due to speed restrictions during operation of the work machine. The speed restrictions 114 contain, for example, a speed-dependent minimum input speed characteristic 116 for the drive transmission and, in further embodiments, additional speed boundary conditions 118. In a step 120, parts of speed characteristics or entire speed characteristics are truncated in order to exclude them from the control map.

[0032] In a step 122, a required transmission input power is determined based on the efficiency maps and a driving speed of the work machine. The transmission input power corresponds to a drive power with deactivated auxiliary consumers. In one embodiment, the operating state of auxiliary consumers is not taken into account. In the embodiment shown here, speed-dependent characteristic curves of auxiliary consumers 126 are read in a step 124 in order to generate a control map dependent on the auxiliary consumer state. In the embodiment shown, auxiliary consumers 126 comprise a fan 128, a water pump 130, an air conditioning compressor 132, and an air compressor 134. In other embodiments, other and additional auxiliary consumers may be provided, which is illustrated by field 136.In a step 138, the power requirement of each activated auxiliary consumer 126 is added to the required drive power. In one embodiment, respective control characteristics can also be determined for different states of the respective auxiliary consumers 126, which is shown in . Fig. 2 is not shown separately as a loop.

[0033] In a step 140, operating points with insufficient drive motor power are excluded. Thus, when determining the respective speed characteristics of the drive motor that correspond to the lowest energy consumption depending on the driving speed, certain operating points can be truncated due to exceeding a speed-dependent maximum power of the drive motor. This truncates parts of the speed characteristics or entire speed characteristics in order to exclude them from the control map.

[0034] In step 142, the energy consumption, in this case fuel consumption, is determined from the read-in characteristic maps of the drive motor and the transmission. Based on this, in step 144, the permissible speed of the drive motor that corresponds to minimum fuel consumption is determined. In step 146, the corresponding transmission ratio, comprising the variator ratio and the driving range, is determined. This results in an operating point optimized for a driving speed and output power with, according to the calculation, the lowest energy consumption. This operating point is temporarily stored in step 148.

[0035] This calculation is performed as a loop at all driving speeds, which is illustrated by step 150. Respective calculations according to Fig. 2 can be performed offline on a computer or online by a vehicle control unit. For example, the loop is run through between engine speeds of 1300 and 2100 in engine speed steps of 100 or 10. This calculation and this loop after step 150 are also performed for all output powers, as illustrated by step 152. For example, between output powers of 1% and 100%, the loop is run through in output power steps of 10% or 1%. In a step 154, an optimal engine speed is permanently stored over the vehicle speed at the respective output powers. In a step 156, an optimal gear ratio or just a corresponding variator gear ratio is permanently stored over the vehicle speed at the respective output powers.From this, in a step 158, a control map is generated, which contains respective control characteristics for driving speed-dependent speed characteristics and corresponding transmission ratios. In the embodiment shown, a corresponding characteristic curve for the speed and the variator ratio can be provided for each combination of activated auxiliary consumers. In other embodiments, a corresponding characteristic curve for the speed and the variator ratio can be provided without taking the auxiliary consumers 126 into account.

[0036] Fig. 3 schematically illustrates a method according to Fig. 2 generated optimized control map of the drive train. A first engine characteristic curve 200 illustrates an optimized engine speed over the driving speed, with the fan being the only auxiliary consumer 126 activated. A first variator characteristic curve 202 illustrates a corresponding inverse variator ratio over the driving speed. It is clear that the variator ratio is not changed directly proportional to the driving speed. Instead, the variator ratio remains at a mechanical point for a specific driving speed range, which is clearly visible in areas 204, 206 and 208, for example. At the mechanical point, a mechanical ratio of the driving transmission, here a planetary assembly in a specific switching state corresponding to the respective driving range, is not changed by the variator. The variator ratio is therefore zero. With a hydrostatic variator as the variator, the variable displacement pump is then at rest.The transmission efficiency is then particularly high. To change the driving speed, the speed of the drive motor is changed instead, which results in... Fig. 3 is also clearly visible.

[0037] A second engine characteristic curve 300 illustrates an optimized engine speed over the driving speed, with no auxiliary consumers activated. A second variator characteristic curve 302 illustrates a corresponding inverse variator ratio over the driving speed. It is clearly evident that the respective auxiliary consumer states in this embodiment have a significant influence on the consumption-optimized control of the transmission and the drive motor. By the method according to Fig. 2, further characteristic curves are determined for all auxiliary consumer states, which are shown in Fig. 3 are not shown. For vehicles without information about the auxiliary consumer states accessible to the control unit, this can be omitted. Instead, a typical auxiliary consumer power can be used as the basis for the entire optimization. Reference symbol 10 Process start step Determine gearbox efficiency map 12 Reading in a transmission structure 14 Reading a wave code 16 Reading a switching matrix 18 Reading in switching element types 20 Reading in a variator type 22 Reading in possible gear ratios 24 Collection of information 26 Start calculation of gearbox efficiency curve 28 Calculation of speeds of all components of the drive gear 30 Calculation of torques of all components of the drive gear 32 Consideration of tensile force limits 34 Traction force calculation 36 Determination of vehicle weight 38 Determination of friction coefficients 40 Determination of output power 42 Determination of tire diameter 44 Determination of axle ratio 46 Operating point of the drive train 48 Determination of load-dependent and speed-dependent torque losses in the drive transmission 50 seals 52 switching elements 54 warehouses 56 gears 58 system pumps 60 Variator 62 brakes 64 loops with all variator ratios in one driving range 66 loop with all driving areas 68 Generation of a gearbox efficiency curve 70 loop with all input speeds 72 loops with all output power 74 Creation of the transmission efficiency map 100 Process start step optimization control map 102 Determination of engine consumption map 104 Reading power and torque characteristics of drive motor 106 Reading transmission efficiency map 108 Determination of transmission efficiency map on test bench 110 Determination of gearbox efficiency map as in Fig. 1 112 Reading in speed restrictions of the drive motor 114 Speed ​​limitations 116 Minimum input speed characteristic 118 additional speed boundary conditions 120 Cutting off speed characteristics 122 Determination of transmission input power 124 Reading speed-dependent characteristics of auxiliary consumers 126 secondary consumers 128 fans 130 water pump 132 air conditioning compressor 134 air compressors 136 additional secondary consumers 138 Addition of power requirements of activated auxiliary consumers 140 Exclusion of operating points with insufficient drive motor power 142 Determination of energy consumption from engine characteristic maps 144 Determination of permissible speed of the drive motor 146 Determination of the gear ratio 148 Temporary storage operating point 150 loop with all speeds 152 loop with all output power 154 Permanent storage of optimal speed 156 Permanent storage of optimal translation 158 Generation of control map 200 first engine characteristic curve 202 first variator characteristic curve 204 first area 208 second area 210 third area 300 second engine characteristic curve 302 second variator characteristic curve

Claims

[1] Method for controlling a drive train of a vehicle, wherein the drive train has a drive motor and a continuously variable transmission, which are each controlled by a control map, wherein the control map has been determined by a method for optimizing (100) the control map of the drive train of the vehicle, wherein the method for optimizing (100) the control map has at least the following steps: - determining (10, 110) a transmission efficiency map; - determining (102) an engine consumption map; - Determining an energy consumption map as a function of different speeds of the drive motor at different driving speeds of the vehicle on the basis of the transmission efficiency map and the engine consumption map; - Determining a speed characteristic of the drive motor which corresponds to the lowest energy consumption depending on the driving speed, on the basis of the determined energy consumption map; - Determining (158) the control characteristic map as a function of the driving speed-dependent speed characteristic and the corresponding gear ratios of the driving transmission characterized by that the drive motor and the continuously variable transmission are only controlled using the control map after the drive train has been operated at a certain operating point for a minimum period. [2] Method according to claim 1, characterized bythat the step of determining the energy consumption characteristic map is carried out as a function of different speeds of the drive motor at different driving speeds of the vehicle and also at different drive powers for each driving speed, wherein the determination of the speed characteristic of the drive motor, which corresponds to a lowest energy consumption as a function of the driving speed, is carried out at the different drive powers in order to generate a speed characteristic map of the drive motor, which corresponds to a lowest energy consumption as a function of the driving speed and drive power, and wherein the determination (158) of the control characteristic map is carried out as a function of the driving speed-dependent and drive power-dependent speed characteristic map and a corresponding gear ratio of the driving transmission. [3] Method according to claim 2, characterized bythat the different drive powers are determined depending on the output power and the transmission efficiency map. [4] Method according to claim 2 or 3, characterized by that the different drive powers are calculated as a function of a speed-dependent power consumption of auxiliary consumers (126). [5] Method according to one of the preceding claims, characterized by that when determining respective speed characteristics of the drive motor which correspond to the lowest energy consumption depending on the driving speed, respective operating points are cut off due to an exceeding of a speed-dependent maximum power of the drive motor (140). [6] Method according to one of the preceding claims, characterized bythat when determining the respective speed characteristics of the drive motor, which correspond to the lowest energy consumption depending on the driving speed, respective operating points are cut off due to speed restrictions during operation of the working machine (120). [7] Method according to one of the preceding claims, characterized by that the method further comprises a step of storing the control map on a data memory and a step of loading the control map into a control unit of the drive train of the vehicle.

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