Transmission control procedure

Abstract

Method for controlling a power-split transmission device (10), in particular in a vehicle (50), wherein the transmission device (10) comprises an electric variator (20) and a transmission with variable ratio (40) to connect a drive motor (52) to a drive (42) of the vehicle (50) and wherein the electric variator (20) comprises a summation gear (30), at least one first and at least one second electric machine (22, 24) and a control (26) of the electric machines (22, 24) for continuously varying a gear ratio of the summation gear (30), in which, upon detection of an external power requirement of an electrical consumer (60), a gear ratio range of the transmission with adjustable gear ratio (40) is set such that the first electrical machine (22) is operated as a generator and the second electrical machine (24) is operated such that an existing power shortfall or power surplus with respect to the external power requirement is compensated.

Description

[0001] The invention relates to a method for controlling a power-split transmission device, in particular in a vehicle, wherein the transmission device comprises an electric variator and a transmission with adjustable gear ratio in order to connect a drive motor to a drive of the vehicle, and wherein the electric variator comprises a summation transmission, at least one first and at least one second electric machine and a control of the electric machines for continuously varying a gear ratio of the summation transmission.

[0002] Continuously variable transmissions are commonly found in construction and agricultural machinery, such as tractors, particularly in the premium segment, and are designed as hydraulic-mechanical power-split transmissions. The power flow is divided into a mechanical path, usually routed via one or more planetary gear sets, and a hydrostatic path, in which the power is routed via a hydrostatic variator, which allows for continuously variable gear ratio adjustment. Such transmissions are available on the market from manufacturers such as John Deere and Fendt.

[0003] DE 197 49 074 C2 and DE 10 2012 204 477 A1 disclose continuously variable transmission devices in which the variable path is embodied as an electric variator. In such electromechanical transmissions, both mechanical and electrical power are used as drive power. DE 10 2011 087 946 A1 discloses a drive arrangement with an internal combustion engine and an electrically continuously variable transmission, wherein the drive arrangement comprises an electrical intermediate circuit with a first electric machine driven by the internal combustion engine as a generator and at least one second electric machine connected to the transmission as a motor.

[0004] Another development trend for construction machinery and agricultural vehicles involves the construction of a second electrical system, operating at a higher rated voltage, in addition to the existing electrical system of the machine. This second electrical system can be used to power electrical consumers that require a higher rated voltage for their operation. These electrical consumers can be located either on the machine itself or on an attachment. Traditionally, this additional second electrical system is generated on the machine by a dedicated generator system. However, this results in additional product costs and reduces overall efficiency due to the additional components.

[0005] Based on this, the object of the present invention is to provide a method with which a second on-board network on the vehicle can be supplied in an integrated manner.

[0006] The object is achieved by a method according to the preamble of claim 1, in which, according to the invention, when an external power requirement of an electrical consumer is detected, a gear ratio range of the transmission with adjustable gear ratio is set such that the second electrical machine is operated as a generator and the first electrical machine is operated such that an existing power shortfall or power surplus with respect to the external power requirement is compensated.

[0007] The first electric machine can preferably be operated with voltage control. This produces or consumes the electrical power required to regulate a DC link. The second electric machine can be operated with speed control. This produces or consumes the electrical power to adjust the ratio of the summing gear via the speed of the second electric machine, depending on the current traction requirement of the vehicle. Cogeneration is a state in which both electric machines are operated as generators. In this context, an external power requirement is understood to mean a power requirement that arises outside the transmission device.Thus, the external power requirement can, for example, originate from an electrical consumer located on the work vehicle or from an electrical consumer located on an attachment of the work vehicle.

[0008] In this context, a power shortage or power surplus is understood to mean a difference between the electrical power generated by the two electrical machines or only one of the electrical machines and the level of the external power requirement, in the sense that a shortage exists when the external power requirement exceeds the generated electrical power, and that a surplus exists when the generated electrical power exceeds the external power requirement.

[0009] It may happen that the second electrical machine generates a certain amount of electrical power, but there is a higher external power requirement. In order to at least partially compensate for this difference, the first electrical machine can also be operated as a generator. On the other hand, it may happen that the second electrical machine generates a certain amount of electrical power, but there is a lower external power requirement. In order to compensate for this difference, which then represents a power surplus, the first electrical machine is operated as a motor in order to absorb this power surplus and feed it back into the summation gear as reactive power.

[0010] According to the invention, it has now been recognized that reactive power flowing in the variator branch opposite to the original direction can be used to meet an external power requirement. For this purpose, a gear ratio range of the transmission with adjustable gear ratio can be specifically set such that the summation gear delivers power to the variator branch. This power delivered to the variator branch is not fed back into the summation gear as reactive power, since according to the invention it is dissipated as electrical power via the second electrical machine and the controller to meet the external power requirement. If the external power requirement cannot be met by the second electrical machine alone, the first electrical machine can also be operated as a generator, so that both electrical machines are operated in the sense of cogeneration.The advantage of this operating mode is that an external power requirement can be met by means of two electrical machines, so that the power level of each individual machine and the corresponding electronics can be reduced.

[0011] The summation gear is preferably formed by a planetary gear with three drive interfaces, wherein, depending on the direction of the power flow, the drive interfaces can act as the input or output of the planetary gear. It can be provided that the drive motor is drive-connected to the first drive interface of the planetary gear in order to supply the transmission device with drive power, which in turn can be passed on to the travel drive via the gear with adjustable transmission ratio connected to the second drive interface of the planetary gear. Furthermore, it can be provided that the second of the two electric machines is drive-connected to the third drive interface of the planetary gear in order to represent a variable transmission ratio between the first drive interface and the second drive interface of the planetary gear.Preferably, the second of the two electric machines is drive-connected to the drive motor of the work vehicle, whereby this can be done with the interposition of a transmission in the form of a spur gear stage.

[0012] While the work machine is driven by the drive motor, the second electric machine can operate in generator mode and motor mode. Generator mode generates electrical power, which by definition has a negative sign, while motor mode requires or consumes electrical power. The power requirement in motor mode or the power output in generator mode of the second electric machine depends on the required tractive force of the work vehicle and the necessary speed of the second electric machine to achieve the set gear ratio of the planetary gear.

[0013] In the event of an external power requirement, a transmission ratio range with adjustable gear ratio can be selected so that the second electric machine is operated in generator mode. The electrical power output by the second electric machine in generator mode can be made available to an external electrical consumer via the controller in order to meet an existing external power demand. Overall, the transmission control method according to the invention increases the overall efficiency achieved at the output shaft and the control of the transmission device, since the electrical power of the second machine has to be generated anyway to meet tractive force requirements. The advantage now is that this electrical power is not fed back into the planetary gear train as reactive power via the variator branch, but is made available to an external electrical consumer via the controller.

[0014] Preferably, a transmission ratio is set taking into account driving resistance, external power demand, and a desired driving speed. This ensures that a transmission ratio range with adjustable ratio is only activated, or that a gear ratio range other than the current one is only activated, when the current driving resistance and driving speed permit.

[0015] Preferably, an energy storage device connected to the controller is provided to compensate for any existing power surplus or shortfall in relation to the external power demand. This ensures that in the event of a power surplus, even less power circulates as reactive power, and in the event of a power shortfall, power can be added from the energy storage device.

[0016] Preferably, the control system adjusts the torque of the electrical machines independently of the speed of the electrical machines in order to feed energy into each of the electrical machines or an energy storage device and to operate each of the two electrical machines as a generator.

[0017] The invention is described below with reference to the figures, in which Fig. 1 an agricultural work vehicle with an attachment; Fig. 2a - 2c Block diagrams of a drive arrangement with different power flows; Fig. 3a a drive arrangement for implementing the transmission control method according to the invention; Fig. 3b Speed-speed diagram for the drive arrangement according to Fig. 3a; Fig. 3c electrical power curves over the vehicle speed without transmission control according to the invention for the drive arrangement according to Fig. 3a; Fig. 3d electrical power curves versus vehicle speed with transmission control according to the invention; Fig. 4a further drive arrangement for implementing the transmission control method according to the invention; Fig. 4b Speed-speed diagram for the drive arrangement according to Fig. 4a; Fig. 5a further drive arrangement for implementing the transmission control method according to the invention; Fig. 5b Speed-speed diagram for the drive arrangement according to Fig. 5a; Fig. 6a further drive arrangement for implementing the transmission control method according to the invention; Fig. 6b Speed-speed diagram for the drive arrangement according to Fig. 6a and Fig. 7a, Fig. 7b further drive arrangements for implementing the transmission control method according to the invention.

[0018] The Fig. 1 shows a possible arrangement of an agricultural work vehicle 50 with a power-split transmission device 10, only indicated schematically, which is driven by a drive motor 52 and is designed to provide electrical power to an electrical consumer 60 in the form of an electric drive axle on an attachment 56 via a controller 26 and a power interface 54 in the form of an AEF connector. Furthermore, drive power is transmitted to a travel drive 42 via the transmission device 10. The travel drive 42 can comprise a differential gear 48 and a drive axle 44 with wheels 58. In addition, an energy storage device 27 connected to the controller 26 can be provided to store and release electrical power. The energy storage device 27 can be a battery device, for example. This arrangement is only one possible example.Thus, the electrical consumer 60 does not necessarily have to be an electric drive axle, nor does it have to be located on the attachment 56, but can equally be located on the work vehicle 50. Instead of an AEF connector, another standardized or non-standardized interface can be used.

[0019] The Fig. 2a-2c show a block diagram of a possible drive arrangement of the agricultural work vehicle 50. A drive motor 52 in the form of an internal combustion engine transmits its drive power to a transmission device 10. Starting from the transmission device 10, the drive power is transmitted to a travel drive 42, which may include components such as a differential gear and a drive axle with wheels.

[0020] The transmission device 10 comprises a variator 20, consisting of at least one summation transmission 30, at least one first electric machine 22, at least one second electric machine 24, and a controller 26, and a transmission with variable transmission ratio 40. The second electric machine 24 can continuously adjust a transmission ratio of the summation transmission. The transmission with variable transmission ratio 40 can be designed as a group-shift transmission with, for example, five shift groups A, B, C, D, and E. In a specific embodiment, the transmission 40 can be designed as a dual-clutch transmission or as a continuously variable transmission. The controller 26 can be connected to an electrical consumer via a power interface 54.The transmission device 10 can also include a reversing gear 28, which can be configured as a planetary gear, and a creeper gear 46, which can be configured as a planetary gear. Both the reversing gear 28 and the creeper gear can be connected upstream or downstream of the summing gear 30.

[0021] The torque of the two electric machines 22, 24 can be adjusted via the controller 26 independently of the speed of the two electric machines 22, 24. Depending on the gear ratio of the summing gear 30 to be set, the second electric machine 24 can be operated in one direction of rotation in motor mode and in the opposite direction in generator mode. If a gear ratio is to be set for the summing gear 30 that requires motor operation of the second electric machine 24, the first electric machine 22 is operated in generator mode, and the electrical power generated thereby is made available to the second electric machine 24 for its motor operation.

[0022] This case of control can be explained by the Fig. 2a in qualitative terms. The flow of power units is shown using arrowheads, with one power unit symbolized by an arrowhead. It is assumed that the drive motor 52 delivers four power units, of which three power units flow into the summing gear 30 and one power unit flows via the variator 20 into the summing gear 30, so that ultimately four power units flow toward the manual transmission 40.

[0023] If a gear ratio is to be set for the summing gear 30 that requires generator operation of the second electric machine 24, this generates electrical power that can be made available to another electrical consumer. A distinction must be made between two scenarios: In the first scenario, there is no external power requirement, so the controller 26 controls the first electric machine 22 in motor mode and makes the electrical power generated by the second electric machine 24 available to it. This first scenario can be described using the Fig. 2b in qualitative terms. Again, it is assumed that the drive motor 52 delivers four power units. However, since the second electrical machine 24 is operated in generator mode, one power unit flows via the summing gear 30 to drive the second electrical machine 24. This power unit, which is not dissipated externally, flows back via the first electrical machine 22, which is operated in motor mode, to the input of the summing gear 30, so that together with the four power units delivered by the drive motor 52, five power units flow into the summing gear 30. Since one power unit of this in turn flows off to drive the second electrical machine 24, four power units flow off towards the gear 40. This power increase by one power unit within the summing gear 30 results from the reactive power circulating backwards via the variator 20.

[0024] In the second scenario, there is an external power requirement, so that the electrical power generated by the second electric machine 24 can be made available to an external consumer, for example, the electric drive axle of an attachment. This second scenario can be described using the Fig. 2c will be explained in qualitative terms. In the Fig. 2c, the power unit generated by the second electric machine 24 is made available to an external electrical consumer via the controller 26 and the AEF connector 54 in order to meet a corresponding external power requirement. In addition, the first electric machine 22 is controlled by the controller 26 in generator mode, and the two power units generated by the two electric machines 22, 24 are made available to an external electrical consumer via the AEF connector 54. Accordingly, only two power units flow towards the travel drive 42. Only in a special case not shown here can the controller 26 control the first electric machine 22 in an idle state, so that accordingly, of the four power units of the drive motor 52, only three power units flow towards the travel drive 42 and one power unit flows via the AEF connector 54.

[0025] In the following, the Fig. 3a-7b describe various possible configurations of transmission devices and the corresponding implementation of the transmission control method according to the invention. In principle, a distinction must be made between a configuration ( Fig. 3a, Fig. 3b, Fig. 4a, Fig. 4b), in which a speed jump of the second electric machine 24 is to be carried out when changing the gear ratios of the transmission 40 and a configuration ( Fig. 4a - 5b), in which no or only a very small speed jump of the second electric machine 24 is to be carried out when changing the gear ratios of the transmission 40. Furthermore, the transmission devices of the Fig. 3a - 5b are input-coupled arrangements.

[0026] In the Fig. 3a-3d, components already described in the previous figures are given a reference number raised by 100. The Fig. 3a shows a drive arrangement of the agricultural work vehicle, in which a drive motor 152 in the form of an internal combustion engine transmits its drive power to a travel drive 142 via a reversible planetary gear train 128 that can be engaged as needed and a transmission device 100 according to the invention. The travel drive 142 can usually comprise a differential gear 148 and a rear drive axle 144 with wheels 158. The transmission device 100 comprises an electric variator 120, consisting of a summation gear 130 in the form of a planetary gear train and a first electric machine 122 and a second electric machine 124 for continuously adjusting a gear ratio of the summation gear 130, and a transmission with adjustable gear ratio 140 in the form of a range-shift transmission with, in this case, five shift groups A, B, C, D, and E.The variator 120 corresponds to the configuration according to which a speed jump of the second electric motor 124 is to be performed when changing the gear ratios of the transmission 140. A creeper gear 146, which can be engaged as needed, can be arranged directly downstream of the planetary gear 130. The two electric motors 122, 124 are connected to the AEF connector 154 via the controller 126. Additional outputs (not shown) can be provided, for example, an output for a power take-off drive or an output for a front-wheel drive that can be engaged as needed.

[0027] The planetary gear train 130 is driven by the drive motor 152 via the ring gear 134 of the planetary gear train 130, and the output in the direction of the transmission 140 is via the planet gear carrier 138 of the planetary gear train 130. For this purpose, the ring gear 134 can be drive-connected to the drive shaft 164 of the drive motor 152 via a switching element 162. The second electric machine 124 is drive-connected to the sun gear 136 of the planetary gear train 130 via a first spur gear stage 166 in order to continuously vary the gear ratio between the driven ring gear 134 and the driving planet gear carrier 138 of the planetary gear train 130. The first electric machine 122 is drive-connected to the drive shaft 164 of the drive motor 152 via a second spur gear stage 168.

[0028] In the present embodiment, the transmission 140 is designed as a dual-clutch transmission with a first countershaft 170, a second countershaft 172, and an output shaft 174. A first gear 176 mounted on the first countershaft 170 and a second gear 178 mounted on the second countershaft 172 are in meshing engagement with the planetary gear carrier 138 of the planetary gear transmission 130. The first gear 176 can be connected to the first countershaft 170 via a shift element 180, and the second gear 178 can be connected to the second countershaft 172 via a shift element 182. Starting from the countershafts 170, 172, a power flow can be switched to the output shaft 174 via gear pairs and switching elements not to be described in detail, which in turn drives the drive 142. Fig. Figure 3b shows a speed-speed diagram in which the speed curves of the second electric machine 124 are plotted against the driving speed of the work vehicle 150 for the five gear ratio ranges A, B, C, D, E of the transmission 140. The second electric machine 124 is in generator mode when the absolute value of the speed is positive, i.e., in the upper half of the Fig. 3b. The electrical power generated in generator mode must either be circulated as reactive power via the first electrical machine 122 operating in motor mode if there is no external power demand, or it can be used to meet an existing external power demand. If there is an external power demand, the second electrical machine 124 can, by appropriately selecting the respective gear ratio range of the transmission 140, run its speed curves as consistently as possible within the range corresponding to a generator mode.This can be achieved by changing the gear ratio range of the transmission 140 when the lowest driving speed that can be achieved with a speed curve of the second electric machine 124 is below the driving speed that is achieved with the next lower speed curve of the second electric machine 124 at the point at which this lower speed curve switches between generator and motor mode. Therefore, if there is an external power requirement, the second electric machine 124 can be operated as a generator by appropriately selecting the gear ratio range of the transmission 140. At the same time, if the external power requirement cannot be met by the second electric machine 124 alone, the first electric machine 122 can also be operated as a generator, since it does not have to absorb electrical power in order to circulate it as reactive power during motor operation.

[0029] The Fig. Figure 3c shows a range of electrical power outputs of the two electrical machines 122, 124, plotted against a section of the driving speed of the work vehicle 150 for three gear ratio ranges A, B, C of the transmission 140. The dash-dotted curve corresponds to the electrical power output of the second electrical machine 124 and the dashed curve to the electrical power output of the first electrical machine 122. There is no external power requirement. Fig. Figure 3c shows the result of a calculation of the electrical power, which assumes a speed of the drive motor 152 of 1900 rpm and full power utilization of the drive motor 152. Opposing power curves of the two electrical machines 122, 124 can be seen. The work vehicle 150 accelerates in the first gear ratio range A of the transmission 140. In this gear range, the second electrical machine 124 is initially operated in generator mode and the first electrical machine 122 in motor mode, so that reactive power circulates in the variator 120. This reactive power flow continues until a change in the operating modes of the two electrical machines 122, 124 takes place, so that the second electrical machine 124 is operated in motor mode and the first electrical machine 122 is operated in generator mode, and no reactive power circulates.When the two electric machines 122, 124 again reach their maximum power value, the transmission 140 shifts into the second gear ratio range B, and the work vehicle 150 accelerates further. For both this and the further illustrated gear ratio range C of the transmission 140, the electrical power curves of the two electric machines 122, 124 correspond to those just described for gear ratio range A. This means that after shifting into the gear ratio range, reactive power initially circulates in the summation transmission 130 until, upon further acceleration, the second electric machine 124 operates in motor mode and the first electric machine 122 operates in generator mode.

[0030] The Fig. Figure 3d shows the result of a calculation of the electrical power using the transmission control method according to the invention. Here, too, a speed of the drive motor 152 of 1900 rpm and a full power utilization of the drive motor 152 are assumed. Furthermore, a maximum externally delivered power of X kW is assumed in order to cover an external power requirement. The amount of X kW of externally delivered power is merely an assumed value for the present calculation, which may vary in reality. Compared with the Fig. 3b are in the Fig. 3c, the electrical power curves of the two electrical machines 122, 124 are fundamentally the same. This means that after a change in the gear ratio ranges of the manual transmission 140, the two electrical machines 122, 124 change their operating modes, which, however, cannot occur so quickly in reality due to the not infinitesimally short switching times, and while passing through the gear ratio ranges, the electrical power curves of the two machines 122, 124 run with opposite gradients to each other and cross within a gear ratio range. In contrast to Fig. 3b are in the course of the Fig. 3c, the shift points between the gear ratio ranges of the manual transmission 140 have been selected according to the invention such that they are carried out earlier, relative to the driving speed, and the ranges in which both electric machines 122, 124 are operated in generator mode are enlarged or broadened relative to the driving speed ranges. Compared with the Fig. 3b, in which in certain areas a power component circulates as reactive power in the variator 120, is used in the Fig. 3c, this power component is made available to an external electrical consumer via the controller 126 as external power and at least predominantly does not circulate in the variator 120. In the Fig. 3c, only relatively narrow areas can be seen in relation to the driving speed, in which reactive power circulates in the variator 120. In these areas, the power generated by the second electric machine 124 exceeds the power output of X kW externally, so that the first electric machine 122 is operated as a motor in order to absorb this excess power, which then circulates as reactive power in the variator 120. Fig. 3c shows areas in which the second electrical machine 124 is operated as a motor and the first electrical machine 122 is operated as a generator, although the electrical power generated by the first electrical machine 122 exceeds the power consumed by the second electrical machine 124, so that the power exceeding the power requirement of the second electrical machine 124 can be made available as external power.

[0031] In the following, the Fig. 4a to 5b describe drive arrangements of an agricultural work vehicle with a configuration which requires no or only a very slight jump in the speed of the second electric machine 224, 324 when changing the gear ratios of the transmission 240, 340.

[0032] In the Fig. 4a, Fig. 4b, components already described in the previous figures are again provided with a reference number raised by 100. The Fig. 4a shows a transmission device 200 for an agricultural work vehicle, driven by a drive motor 252, with a variator 220 and a transmission 240 comprising three planetary gear sets 2341-2343 and five shift elements 2361-2365. The variator 220 comprises a summation gear 230, a first and a second electric machine 222, 224 and a controller 226. A description of the operation of the transmission device 200 according to Fig. 4a is waived.

[0033] The Fig. Figure 4b shows a speed-speed diagram in which the speed curves of the second electric machine 224 are plotted against the driving speed of the work vehicle for four gear ratio ranges of the transmission device 200. The second electric machine 224 is in generator mode on the portion of each speed curve that adjoins the zero crossing of the respective speed curve on the left.If there is an external power requirement, the most continuous generator operation of the second electric machine 224 can be achieved by a suitable selection of the set gear ratio range of the transmission 240 if the lowest driving speed that can be achieved with a speed curve of the second electric machine 224 is below the driving speed that is achieved with the next lower speed curve of the second electric machine 224 at the point at which this lower speed curve changes between generator and motor mode.

[0034] In the Fig. 5a, Fig. 5b, components already described in the previous figures are again provided with a reference number raised by 100. The Fig. 5a shows a transmission device 300 for an agricultural work vehicle, driven by a drive motor 352, with a variator 220 and a group shift transmission 340 with three shift groups. A reversing gear 328 can be provided between the drive motor 352 and the variator 320. A creeper gear (not shown) can also be provided. The variator 320 comprises two summation gears 3301, 3302, a first and a second electric machine 322, 324, a controller 326, and two gear ratio stages 3321, 3322, via which the power flow is respectively conducted into the group shift transmission 340. As a result of the two summation gears 3301, 3302 and the three shift groups of the group shift transmission 340, six gear ratio ranges result in the transmission device 300. A further description of the operation of the transmission device 300 according to Fig. 5a is omitted.

[0035] The Fig. Figure 5b shows a speed-speed diagram in which the speed curves of the second electric machine 324 are plotted against the driving speed of the work vehicle for the six gear ratio ranges of the transmission device 300. Regarding the description of the speed-speed diagram of the Fig. 5b refers to the corresponding description of the Fig. 4b, since the speed curves of the Fig. 4b and Fig. 5b qualitatively.

[0036] In the Fig. 6a, Fig. 6b, components already described in the previous figures are again provided with a reference number raised by 100. The Fig. 6a and Fig. 6b shows an output-coupled transmission device 400 driven by a drive motor 452, comprising a variator 420 and a group-shift transmission 440 with three shift groups. The variator 420 comprises a summing transmission 430, a first and a second electric machine 422, 424, and a controller 426. The first electric machine 422 is driven via the sun gear 432 of the summing transmission 430, with the drive being carried out via a hollow shaft 442 by the group-shift transmission 440. The second electric machine 424 is driven via the ring gear 434 of the summing transmission 430. A further description of the operation of the transmission device 400 according to Fig. 6a is omitted.

[0037] The Fig. Figure 6b shows a speed-speed diagram in which the speed curves of the second electric machine 424 are plotted against the driving speed of the work vehicle for the three gear ratio ranges of the transmission device 400. Regarding the description of the speed-speed diagram of the Fig. 5b refers to the corresponding description of the Fig. 3b, since the speed curves of the Fig. 3b and Fig. 6b qualitatively, with the difference that in Fig. 6b the second electric machine 424 is in generator mode when the magnitude of the speed is negative, that is in the lower half of the Fig. 6b.

[0038] In the Fig. 7a, Fig. 7b, components already described in the previous figures are again provided with a reference number raised by 100. The Fig. 7a and Fig.7b each show an embodiment of a compound-coupled transmission device 500, 600. A compound-coupled configuration requires close interaction between both electrical machines 522, 624, 522, 624, since neither is directly coupled to an input speed or an output speed of a summation transmission. Rather, each of the electrical machines can be controlled such that they are operated proportionally and complementarily with voltage control or speed control. In the compound-coupled transmission device 500, 600 shown, the transmission 540, 640 can also be operated in a gear ratio range such that both electrical machines 522, 624, 522, 624 can be operated as generators.

[0039] In summary, a transmission control system according to the invention for the exemplary transmission device described above provides the possibility of operating both electric motors in generator mode, thereby increasing the overall efficiency of the transmission device. Furthermore, the transmission control method provides the possibility of generating electrical power on a relevant scale with the existing transmission device. List of reference symbols 10 Gear device 20 Variator 22 electric machine 24 electric machine 26 Control 27 energy storage 28 reversing gears 30 summing gears 40 gearboxes 42 Drive 44 Drive axle 46 Creeper gearbox 48 differential gears 50 work vehicles 52 drive motor 54 Power interface 56 attachments 58 wheels 60 electrical consumers 134 ring gear 136 Sun gear 138 planetary gear carrier 162 switching element 164 drive shaft 166 spur gear stage 168 spur gear stage 170 countershaft 172 countershaft 174 Output shaft 176 first gear 178 second gear

Claims

[1] Method for controlling a power-split transmission device (10), in particular in a vehicle (50), wherein the transmission device (10) comprises an electric variator (20) and a transmission with variable ratio (40) to connect a drive motor (52) to a drive (42) of the vehicle (50) and wherein the electric variator (20) comprises a summation gear (30), at least one first and at least one second electric machine (22, 24) and a control (26) of the electric machines (22, 24) for continuously varying a gear ratio of the summation gear (30), in which, upon detection of an external power requirement of an electrical consumer (60), a gear ratio range of the transmission with adjustable gear ratio (40) is set such that the first electrical machine (22) is operated as a generator and the second electrical machine (24) is operated such that an existing power shortfall or power surplus with respect to the external power requirement is compensated. [2] Method according to claim 1, characterized by that a gear ratio of the transmission (40) is set taking into account a driving resistance, the external power requirement and a desired driving speed. [3] Method according to claim 1 or 2, characterized by that an energy storage device (27) connected to the controller (26) is provided in order to compensate for an existing power surplus or power shortage in relation to the external power requirement. [4] Method according to one of claims 1 to 3, characterized by that a torque adjustment of the electrical machines (22, 24) can be carried out via the control (26) independently of the speed of the electrical machines (22, 24) in order to feed energy into each of the electrical machines (22, 24) or an energy store (27) and to operate each of the two electrical machines (22, 24) as a generator.

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