DE102022116593A1 - Method for charging an energy storage unit of a trailer vehicle as well as control device and trailer vehicle - Google Patents

Abstract

The invention relates to a method (100) for charging an energy storage device (74) of a trailer vehicle (14) with an electric drive (72). The method (100) includes monitoring (102) a charge state (104) of the energy storage device (74) and estimating (110) an operating state (138) of the towing vehicle (12) towing the trailer vehicle (14) with a control device (54). Trailer vehicle (14). The method (100) further comprises activating (144) a dynamo mode (146) in the event that the charge state (104) indicates a charge (105) of the energy storage (74) below a minimum threshold value (108) and the operating state (138) indicates a permissible operating state (140), wherein in dynamo mode (146) the electric drive (72) is controlled in order to provide energy for the energy storage (74). The invention further relates to a control device (54), a trailer vehicle (14) with a control device (54) and a team (10) with a towing vehicle (12) and a trailer vehicle (14).

Description

The invention relates to the field of commercial vehicles and in particular trailer vehicles or trailers for short, which are designed in particular as commercial vehicles. A trailer vehicle designed as a commercial vehicle is towed by a commercial vehicle designed as a towing vehicle. Such trailer vehicles referred to here include in particular semi-trailers and drawbar trailers.

According to the prior art, commercial vehicles that are designed as towing vehicles are primarily equipped with a primary drive, which is usually an internal combustion engine, in order to drive the towing vehicle and possibly tow a trailer vehicle. Trailer vehicles that are towed by the towing vehicle are increasingly being designed with a drive, which can in particular be an electric drive. It is therefore known to form a combination of a towing vehicle with an internal combustion engine and a trailer vehicle with an electric drive. Such a team is also known as a hybrid team.

The electric drive in the trailer vehicle is primarily used to support the primary drive. For example, the drive in the trailer vehicle is used to support an internal combustion engine of the towing vehicle by providing additional thrust when starting or driving uphill. In addition, the electric drive can be used to recover kinetic and potential energy of the team, for example when braking, and store it as electrical energy in one or more energy storage devices. This energy can be made available again for propulsion if necessary. An electric drive also serves to support or fully implement a required negative acceleration, namely braking. In a particularly advantageous manner, the friction brakes of the towing vehicle and the trailer vehicle are protected.

For optimal use of an electric drive in the trailer vehicle, trailer vehicles with such an electric drive include one or more energy storage devices with a capacity that is very high compared to common energy storage systems that are otherwise used in the vehicle sector to supply auxiliary consumers. Due to the high capacity of an energy storage device in a trailer vehicle that includes an electric drive, the energy storage device can also be used to supply additional consumers in the trailer vehicle. An extended use of the energy storage device(s) is possible. Particularly in the case of a trailer vehicle, which allows, for example, temperature-controlled transport, units have hitherto been provided, in particular for cooling a transport space of the trailer vehicle, which were fed with energy from a diesel generator of the trailer vehicle. Such diesel generators are usually already part of the unit. Due to the energy storage of the trailer vehicles mentioned with electric drive, such diesel generators can now be dispensed with and an aggregate, such as a cooling unit, can be supplied with energy from the energy storage of the electric drive.

However, the extended use of the energy storage device(s) of an electric drive places high demands on the state of charge of the energy storage device. In the case of simply supplying electric motors of the electric drive through the energy storage, an insufficient charge state of the energy storage is usually not critical, since the electric drive only intervenes in a supportive manner anyway. Overall, a primary drive of the towing vehicle as well as braking devices of the towing vehicle and the trailer vehicle are designed so that they can optimally carry out driving operations even without support. However, if the energy storage device is used for temperature control, in particular for cooling, a transport space or transport volume of the trailer vehicle, the state of charge is comparatively critical. For example, when transporting food, cooling must often not be interrupted, otherwise the goods will spoil. An interruption in cooling could be the result of a discharged energy storage unit.

The object of the present invention is therefore to address the problems of the prior art. In particular, a possibility for charging the energy storage of an electric drive of a trailer vehicle should be found, which provides sufficient energy in the energy storage of the trailer vehicle for a required supply of consumers of the trailer vehicle. In any case, an alternative to the state of the art should be found.

To this end, the invention relates to a method for charging an energy storage unit of a trailer vehicle according to claim 1.

The invention relates to a method for charging an energy storage unit of a trailer vehicle with an electric drive. The trailer vehicle is, for example, a semi-trailer or a drawbar trailer. The energy storage serves, for example, to supply one or more electric motors of the electric drive and to absorb electrical energy in a recuperation mode in which the electric motor or motors are used for braking in generator mode. The energy storage in particular has a capacity of more than 25 kWh, in particular more than 50 kWh, for example 100 kWh.

To charge the energy storage device, the method first includes monitoring the state of charge of the energy storage device. Monitoring the state of charge includes at least detecting the charge, i.e. the available energy, in the energy storage.

The method further includes estimating an operating state of the towing vehicle towing the trailer vehicle using a control unit of the trailer vehicle. The operating state of a towing vehicle towing the trailer vehicle is therefore estimated using the control unit of the trailer vehicle itself from parameters present in the control unit. An operating state is therefore not transmitted from the towing vehicle to the trailer vehicle, but rather the operating state in the trailer vehicle itself is estimated, in particular based on parameters present in the trailer vehicle.

Furthermore, the method includes activating a dynamo mode in the event that the charge state indicates a charge of the energy storage below a minimum threshold and the estimated operating state is a permissible operating state. According to the method, the charge state of the energy storage is monitored and a current charge of the energy storage is recorded. The load is compared to a minimum threshold. In addition, an operating state of the towing vehicle is estimated, with the result of the estimation yielding an operating state that corresponds to either a permissible operating state or an impermissible operating state.

If the comparison of the load with the minimum threshold shows that the load is below the minimum threshold and the estimate of the operating state shows that a permissible operating state is present, the dynamo mode is activated. If one or both conditions are not met, namely if the detected charge is above the minimum threshold value and/or the estimated operating state corresponds to an impermissible operating state, then the dynamo mode is not activated. According to the method, in dynamo mode, the electric drive of the trailer vehicle is operated in a generator mode in order to provide electrical energy for the energy storage.

According to the invention, it is therefore possible to detect a charge of an energy storage device that is below a minimum threshold value. Such a state of charge indicates that the energy storage is about to be charged too low and is no longer sufficient to supply the components of the trailer vehicle as desired. If this state of charge is detected, it can be remedied according to the invention by activating a dynamo mode in order to operate the electric drive in generator mode to charge the energy storage device. This is based on the knowledge that a primary drive, in particular an internal combustion engine, of a towing vehicle can generate the additional torque that is required by the electric drive in generator operation, i.e. in dynamo mode, to generate energy for charging the energy storage.

According to the invention, the electric drive is used not only to support acceleration and braking of a team comprising the trailer vehicle and a towing vehicle towing the trailer vehicle, but also specifically to avoid an energy storage device being charged too little. According to the invention, an operating state of the towing vehicle is estimated and the dynamo mode is only activated if the estimated operating state corresponds to a permissible operating state. A permissible operating state exists if the estimate indicates an operating state in which activation of the dynamo mode will have no or only insignificant negative effects on operation and in particular on the stability of the vehicle combination. A change in acceleration required by the driver, which is not affected by the dynamo mode and can be implemented despite the dynamo mode, corresponds, for example, to a permissible operating state. In contrast, an impermissible operating state is, for example, an operating state in which an acceleration desired by the driver or maintaining the speed by activating the dynamo mode could no longer be implemented by a primary drive of the towing vehicle. Another example of an impermissible operating condition would be an estimated operating condition that indicates an impending or current hazardous situation. The estimated operating state is therefore assigned to a permissible operating state or an impermissible operating state.

An energy storage device is thus automatically charged by means of a control unit on the trailer vehicle when the charging status of the energy storage device is reached chers indicates that the charge is too low, at the same time activating the dynamo mode for the driver or the towing vehicle due to the estimation of the operating state and assignment of the estimated operating state to a permissible or impermissible operating state remains essentially unnoticed. A trailer vehicle with an electric drive, which is set up according to the invention to charge the energy storage as needed, can therefore act independently without an operating state having to be transmitted from the towing vehicle to a control unit of the trailer vehicle. Since the operating state of the towing vehicle is estimated directly in the trailer vehicle itself, older towing vehicles that do not have corresponding interfaces for communicating an operating state to a trailer vehicle can also be operated according to the invention to charge an energy storage device.

According to a first embodiment, the minimum threshold is constant and predefined. According to an alternative to this embodiment, the minimum threshold value can be set, in particular by a user. The control unit therefore has, for example, an interface with which the minimum threshold value can be set, for example depending on the design of the trailer vehicle. If, for example, the trailer vehicle is designed as a vehicle for temperature-controlled transport, for example with a cooling unit, then in particular the minimum threshold value can be set so that sufficient energy is available to supply the cooling unit for a predefined period of time, for example a nightly break. If, on the other hand, the trailer vehicle, as just described, is designed for temperature-controlled transport but is not intended for long-distance use, the minimum threshold value can be set comparatively lower.

According to a further alternative of this embodiment, a power consumption forecast value is determined with the control device and the minimum threshold value is set depending on the power consumption forecast value, in particular automatically by the control unit of the trailer vehicle. The power consumption forecast value is a value that indicates what energy is expected to be consumed in the trailer vehicle to supply auxiliary consumers, such as a refrigeration unit.

The minimum threshold value is therefore suitably predefined, constant or automatically adjustable and can thus be set up for use or training of the trailer vehicle. This is to ensure that an activated dynamo mode requires additional energy from the primary drive of the towing vehicle and should therefore be avoided if possible, while at the same time ensuring that the dynamo mode is activated as often as necessary in order to supply energy to an auxiliary consumer of the trailer vehicle ensure.

In particular, the minimum threshold is in the range from 25% to 45%, in particular between 30% and 40%, of the capacity of the energy storage.

According to a further embodiment, in dynamo mode, the electric drive is controlled with the control unit in order to generate a power specified by the control unit or to set a negative torque specified by the control unit. Negative torque can also be referred to as braking torque. The control unit is therefore designed in such a way that in dynamo mode it specifies to the electric drive a value for a power to be generated or a value for a negative torque to be applied to charge the energy storage device. Regardless of the speed or a specific driving situation, the control unit can precisely define to what extent the energy storage is charged when dynamo mode is activated.

According to a further embodiment, the power or torque with which the control device controls the electric drive in dynamo mode depends on the estimated operating state. Regardless of the fact that the estimated operating state is assigned to a permissible operating state so that a dynamo mode can be activated at all, the estimated operating state is now examined in more detail and the type of the estimated operating state is used for the control. For example, if the operating state is estimated as an operating state in which a primary drive is operated in an energetically unfavorable operating point, then the power or torque in order to charge the electrical storage can be set in particular in such a way that the operating point of the primary drive is in a comparative to an energetically more favorable operating point. The operation of the primary drive of a towing vehicle pulling the trailer vehicle can thus be shifted from energy-inefficient operating states to comparatively more energy-efficient areas.

The invention is based on the knowledge that the dynamo mode, apart from situations in which the energy required for the dynamo mode to charge the energy storage is completely obtained by driving downhill, always requires additional energy for the driver market drive of the towing vehicle means. However, by adjusting the power or torque depending on the operating state, this additional energy expenditure can be minimized, especially in inefficient operating states of the primary drive.

According to a further embodiment, in dynamo mode, the electric drive is controlled by the control unit in such a way that the power generated by the electric drive is increased with increasing speed up to a predefined threshold speed of the trailer vehicle. It is possible that below the threshold speed, the negative torque to be generated is specified as constant or essentially constant. According to this embodiment, starting from the threshold speed, the electric drive in dynamo mode is controlled by the control device in such a way that the power generated by the electric drive is constant or at least essentially constant.

Here, care is taken to realize that with increasing speed, an additional load on the primary drive due to the dynamo mode can increase without the primary drive being burdened too heavily by the dynamo mode. However, above a certain threshold speed, the power to be generated by the electric drive is kept constant in order not to put too much strain on the primary drive, especially if it is an internal combustion engine. Such excessive loading would, for example, result in the transmission shifting down to a lower gear and thus increasing the speed of the primary drive. This must be avoided, as otherwise there is a risk that if the primary drive is too heavily loaded, additional power required, for example for acceleration or driving uphill, cannot be provided or can be provided insufficiently.

An additional load on the primary drive caused by the dynamo mode is therefore kept to a level in order to negatively influence the efficiency of the primary drive and in particular the driving characteristics perceived by the driver as little as possible.

According to a further embodiment, a battery status of the energy storage device is checked. This test can be carried out, for example, immediately before activating the dynamo mode or immediately after activating the dynamo mode, but before generating electrical energy for charging the energy storage. Depending on the battery condition, the control unit then operates the electric drive in dynamo mode in order to generate power dependent on the battery condition or to set a torque depending on the battery condition. A battery state includes in particular a temperature of the energy storage device.

It is possible, for example, in the event that the energy storage or the environment of the energy storage has a temperature at which the energy storage cannot be charged, just enough electrical energy is generated in dynamo mode with the electric drive that the energy storage cannot be charged further reduced. In particular, for example, a predefined minimum temperature and a predefined maximum temperature are stored, with the electric drive not charging the energy storage in dynamo mode when the minimum temperature falls below or the maximum temperature is exceeded, but sufficient energy is generated to further discharge the energy storage, for example to prevent further consumers connected to the energy storage.

According to a further embodiment, the method includes determining a power consumption of consumers of the trailer vehicle who take energy from the energy storage. These consumers, which can also be called auxiliary consumers, do not include the electric motors of the electric drive. The consumers include, for example, a unit for temperature-controlled transport, namely, for example, a refrigeration unit. After determining the power consumption, the electric drive is controlled by the control unit in dynamo mode in order to generate energy that at least corresponds to the determined power consumption. According to an alternative, a minimum power consumption is set or predefined, for example 20 kW or 30 kW, and the electric drive is controlled by the control unit in dynamo mode in order to generate energy that is at or above the value for the minimum power consumption. In particular, it is possible that energy that corresponds at least to the specific power consumption or at least to the minimum power consumption is only generated from the threshold speed onwards. Less or no energy is then generated below the threshold speed.

If a state of charge of the energy storage has already been detected, which leads to the activation of the dynamo mode, an appropriately set power in the dynamo mode, which is generated with the electric drive, ensures that the state of charge of the energy storage does not drop any further. In this way, the consumers of the trailer vehicle are consumed without drawing any energy supplied with energy from the electric drive from the energy storage.

According to a further embodiment, in the dynamo mode, in the event that further power, for example from another control device or a towing vehicle, is requested and received or determined by the control device, the electric drive is activated to provide the power for the dynamo mode and additionally the other To produce power that corresponds to a requirement for a service.

For example, if the electric drive is already in recuperation mode, for example, since it fulfills the function of a continuous brake and is operated in the manner of a conventional retarder, for example when driving downhill, and the control unit for the dynamo mode provides power in addition to that already generated by the recuperation operation Power is requested, the electric drive is controlled to generate the power for the dynamo mode plus the additional power.

According to a further embodiment, in order to estimate the operating state, a speed and/or acceleration, an inclination and a mass of the trailer vehicle are determined with the control device, in particular with sensors of the control device or sensors that are connected to the control device, and the operating state is determined depending on the Speed and/or acceleration, inclination and mass are estimated.

The operating state, namely in particular a current drive power or drive reserve of the primary drive, can be estimated in this way. This estimated operating state can therefore be used to determine whether an additional load on the primary drive of the towing vehicle is possible for the dynamo mode, i.e. whether the dynamo mode can be activated. In this case, the estimated operating state can be recognized, for example, as a permissible operating state, in which a drive reserve is still available. Otherwise, if the operating state is determined based on the speed and/or acceleration as well as the inclination and mass of the trailer vehicle in such a way that there is presumably no drive reserve for the primary drive available, for example at high speed and simultaneous uphill driving, the estimated operating state is therefore considered an impermissible operating state detected so that the dynamo mode is not activated. Furthermore, an operating point of the primary drive can also be estimated based on this estimated drive power or drive reserve, so that the power to be generated or the torque to be set can be adjusted or selected depending on this operating state.

According to a further embodiment, the operating state is additionally estimated as a function of a performance profile. The performance profile is stored in the control unit and is determined by self-learning of the control unit or through parameterization. The performance profile includes at least a maximum power value of the drive. The maximum power value corresponds, for example, to a nominal power of the primary drive. From the previously determined parameters of speed and/or acceleration, inclination and mass of the trailer vehicle, the level of the currently available drive reserve can be estimated, taking into account the performance profile, which includes different estimated drive powers of the primary drive for these parameters, and thus the amount required by the electric drive Adjust performance and/or decide whether the estimated operating state corresponds to a permissible or impermissible operating state. This essentially ensures that the dynamo mode is only activated when appropriate drive reserves are available, so that driving operation of the vehicle combination remains essentially unaffected.

According to a further embodiment, estimating the operating state includes detecting an active switching process and/or an active braking process of the friction brakes. According to this exemplary embodiment, an estimated operating state, which indicates that a switching process is active or the friction brakes are active in a braking process, leads to preventing deactivation of a previously activated dynamo mode and to preventing activation of a previously deactivated dynamo mode.

Accordingly, the dynamo mode will not be activated if it is deactivated, or deactivated if it is activated, as long as the towing vehicle is switching. This is advantageous because, particularly when disengaging a clutch in the towing vehicle to change the ratio between the primary drive and the drive axles, a brief moment of thrust relief occurs, which is used by systems of the towing vehicle to determine the mass of the towing vehicle. During this mass determination, a dynamo mode that becomes active or passive would lead to a falsification of the result of the mass determination, so that the dynamo mode should not change its activation state during active switching processes, i.e. in particular during a disengaged transmission and shortly after engaging the clutch, i.e. after the switching process has ended. It is possible, that a requested activation or deactivation of the dynamo mode, which is prevented due to an active switching process, only takes place after a predefined duration, for example one second or five seconds, after a re-engagement. In particular, the period from disengaging the clutch to the end of the period after re-engaging can be considered as a switching process.

Furthermore, activating or deactivating the dynamo mode is also prevented when it is estimated that the friction brakes are active. Particularly in the case of safety systems that can be active during a braking process with the friction brakes, such as an anti-lock braking system, switching the dynamo mode on or off could have a negative effect, so that blocking and deceleration times are incorrectly determined. The dynamo mode could cause the safety system to react incorrectly. This is prevented.

According to a further embodiment, the dynamo mode is deactivated when a predefined or parameterized switch-off threshold value of the charge state of the energy storage is detected. This switch-off threshold is, for example, at least 40% or 50% of the capacity of the energy storage. For example, the shutdown threshold is at least 10% of the capacity of the energy storage above the minimum threshold. In particular, this switch-off threshold value can be at least 10% or at least 20% of the capacity of the energy storage below a maximum charge of the energy storage. A possibility of a temporal hysteresis between activation and deactivation of the dynamo mode is therefore created in order to prevent the dynamo mode from being constantly switched on and off, which could lead to damage to the energy storage device. In addition, selecting the switch-off threshold value below a full charge of the energy storage ensures that free capacity is still kept free in the energy storage for the following demands on the electric drive for recuperation.

In one variant, a predefined amount of energy is specified and the dynamo mode is switched off when the predefined amount of energy is reached. An alternative criterion for switching off is thus found, which is independent of a switch-off threshold and yet prevents a disadvantageous constant change between switching the dynamo mode on and off.

According to a third variant, the dynamo mode is deactivated when the operating state that is estimated requires deactivation, in particular when an operating state is estimated that corresponds to an impermissible operating state.

According to one embodiment, even during an already activated dynamo mode, the state of charge of the energy storage device is regularly recorded again, for example at predefined time intervals, and/or the operating state is re-estimated.

According to a further embodiment, the switch-off threshold is constant and predefined, adjustable manually or automatically. In particular, the switch-off threshold value can be automatically adjusted by the control device depending on the power consumption forecast value, which is determined, for example, with the control device. An adjustment of the switch-off threshold is therefore possible.

The invention also includes a control device, which is in particular a brake control device for a trailer vehicle, namely a trailer brake control device. The control device is set up to control an electric drive with at least one energy storage device according to a method of the aforementioned embodiments.

The invention further includes a trailer vehicle with a control device according to the invention. The invention also includes a combination with a towing vehicle and a trailer vehicle according to the invention.

• 1 ein Gespann und
• 2 die Schritte eines Verfahrens gemäß einem Ausführungsbeispiel.

Further embodiments result from the exemplary embodiments explained in more detail in the figures. Show here:

• 1 a team and
• 2 the steps of a method according to an exemplary embodiment.

1 shows a trailer 10 with a towing vehicle 12 and a trailer vehicle 14. The towing vehicle 12 and the trailer vehicle 14 or the trailer 10 can each be referred to as a commercial vehicle. The trailer vehicle 14 is coupled to the towing vehicle 12 via a drawbar 16, so that the towing vehicle 12 and the trailer vehicle 14 are connected to one another. The towing vehicle 12 and the trailer vehicle 14 include several axles 18, each of which has two wheels 20. Each of the wheels 20 is assigned a friction brake 22 in order to brake the wheels 20 with the respective assigned friction brakes 22 in the event of a braking request, namely a requested negative acceleration, which is to be implemented by friction brakes. At least one of the axles 18 of the towing vehicle 12 is through a Pri market drive 24 can be driven, which here is an internal combustion engine 26.

The towing vehicle 12 is driven forward by varying an accelerator pedal position 28 of an accelerator pedal 30, and the towing vehicle 12 is braked by varying a brake pedal position 32 of a brake pedal 34 by an operator or driver of the towing vehicle 12. This results in a desire to increase the speed 36 or a braking request 38 signaled. For this purpose, the accelerator pedal 30 is connected to a vehicle control unit 40. For this purpose, the brake pedal 34 is connected to a towing vehicle brake control unit 42. The vehicle control unit 40 transmits control signals for controlling the primary drive 24 to the primary drive 24 via a data connection or a bus 44. The vehicle control unit 40 also determines a requested positive acceleration from the request for a speed increase 36 and transfers this to the towing vehicle brake control unit 42 via a data connection 46 The towing vehicle brake control unit 42 generates a positive target torque value 50 on a further data connection 48. Furthermore, the braking request 38 is also sent from the brake pedal 34 to the towing vehicle brake control unit 42. From this, a negative target torque value 50 is generated. The towing vehicle brake control unit 42 can thus output a target torque value 50 on the data connection 48 depending on a speed increase 36 or depending on the braking request 38, which corresponds to a torque that is to be generated by an electric drive of the trailer vehicle 14. The towing vehicle brake control unit 42 thus generates a target torque value 50 for the electric drive, which corresponds to a positive or negative value. The generation takes place automatically in the towing vehicle brake control unit 42.

Furthermore, the friction brakes 22 of the towing vehicle 12 are connected to the towing vehicle brake control unit 42, so that in the case of a braking request 38 triggered by the brake pedal 34, this braking request 38 can also be implemented directly as a control of the friction brakes 22 of the towing vehicle 12.

In addition to the data connection 48, via which the target torque value 50 is transmitted, the towing vehicle brake control unit 42 is also connected via a brake control line 52 to a control unit 54, which here corresponds to a trailer brake control unit. A braking request 38 is additionally transmitted to the trailer brake control unit 56 in the form of a brake control pressure 58 via the brake control line 52. A sensor 60 of the trailer brake control unit 56 converts the brake control pressure 58, which is transmitted via the brake control line 52, into a signal and transmits this to a controller 62 of the trailer brake control unit 56. The trailer brake control unit 56 therefore either depends on a braking request received via the data connection 48 in the form of a target torque value 50 or depending on a brake control pressure 58 received via the brake control line 52, in particular if the communication via the data connection 48 is disturbed, converted into a control signal for controlling the friction brakes 22 of the trailer vehicle 14.

In addition, the trailer vehicle 14 has the already mentioned electric drive 72, which has an energy storage device 74 that is rechargeable and can also be referred to as a battery or accumulator. In addition to the energy storage 74, the electric drive 72 includes two converters 76, which use the energy from the energy storage 74 to supply electric motors 78 with energy in order to generate a positive torque. The energy storage 74, the converter 76 and the electric motors 78 correspond to components of the electric drive 72. According to an alternative exemplary embodiment, not shown here but included in the invention, only one electric motor 78 is provided and the electric drive 72 therefore also only includes one converter 76. A single electric motor 78, for example, is used as a central axle drive in combination with a differential gear in a similar manner to an internal combustion engine that acts on an axle as a whole.

The electric motors 78 can also be operated in recuperation mode, which can also be referred to as generator mode, i.e. as a generator. In recuperation mode, electrical energy is fed back into the energy storage 74 via the converter 76. To control the converter 76, the electric drive 72 is connected to the trailer brake control unit 56 via a bus 80.

In addition, the energy storage 74 is connected to a consumer 82, which here is, for example, a cooling unit 84, in such a way as to supply the consumer 82 of the trailer vehicle 14 with energy. In the present example, the energy storage 74 is used to provide energy for cooling an in 1 transport volume of the trailer vehicle 14, not shown. The transport volume is used for temperature-controlled transport of goods.

The trailer brake control unit 56 controls the electric drive 72 and thus specifies for the converters 76 whether the electric motors 78 are operated in generator mode or in motor mode should be used and what torque should be used. In the case of the operation of the electric motors 78 in engine mode, a positive torque is referred to, while the torque, i.e. a value of the torque, in the generator operation of the electric motors 78 is referred to as negative torque. To control the electric drive 72, namely in particular the converter 76, a signal is sent from the trailer brake control unit 56 to the electric drive 72 via the bus 80. In addition, the electric drive sends a status signal 85 to the trailer brake control device 56 in order to inform the trailer brake control device 56, for example, which currently available positive or currently available negative torque or which currently available positive or currently available negative torque change can be provided by the electric drive 72 at the current time . In addition, a state of charge of the energy storage 74 and a temperature of the energy storage 74 are transmitted to the trailer brake control unit 56 by the electric drive 72 via the status signal 85.

Furthermore, at least in the towing vehicle 12, a retarder 86 is arranged on the rear axle 18 on each of the wheels 20. The retarders 86 can also be activated or adjusted by the towing vehicle brake control unit 42.

The towing vehicle brake control unit 42 thus controls all devices for decelerating the vehicle speed, including the friction brakes 22, the retarders 86 and the electric drive 72. The electric drive 72 for generating a feed, i.e. a positive acceleration, is also made possible via the towing vehicle brake control unit 42. This integration of the devices mentioned is carried out automatically by the towing vehicle brake control unit 42 depending on a current operating state, which the towing vehicle brake control unit 42 determines with a processor from information supplied, for example via the bus 44. This operating state can be determined in a simple manner in the towing vehicle 12 using appropriate bus or signal connections. The towing vehicle brake control unit 42 has direct information about drive reserves or a load on the primary drive 24 from the vehicle control unit 40 in order to generate control signals for the electric drive 72 of the trailer vehicle 14.

However, the operating state itself is not transmitted to the trailer vehicle 14 in a standardized manner and no standardization for transmission is provided for this, regardless of the manufacturer. The trailer brake control unit 56 therefore has no direct knowledge of the operating state of the primary drive 24. In particular in older towing vehicles 12 according to an alternative exemplary embodiment 1 , the towing vehicle 12 has a less advanced towing vehicle brake control unit 42, which, for example, does not have any direct data exchange with an engine control unit and is not suitable for controlling an electric drive 72. Also a team 10 with the trailer vehicle 14 according to 1 and such a towing vehicle 12 is encompassed by the invention.

Accordingly, the trailer brake control unit 56 is designed to estimate an operating state of the towing vehicle 12. For this purpose, the trailer brake control unit 56 includes at least one acceleration sensor 90 and an inclination sensor 92. In addition, the trailer brake control unit 56 is connected to at least one wheel speed sensor 94 in order to derive a speed of the trailer vehicle 14 from a wheel speed recorded therewith. In addition, an air bellows 96 for air suspension of the trailer vehicle 14 is also provided on each of the wheels 20 of the trailer vehicle 14. This includes a pressure sensor with which the trailer brake control unit 56 can estimate a mass of the trailer vehicle 14. For a better overview, the air bellows 96 and the wheel speed sensor 94 are shown here only for one of the wheels 20, with each of the wheels in particular comprising a wheel speed sensor 94 and its own air bellows 96 with an integrated sensor. From the mass determined with the air bellows 96, the speed determined with the wheel speed sensor 94, the acceleration determined with the acceleration sensor 90 and the inclination 92 determined with the inclination sensor 92, the trailer brake control unit 56 can infer an operating state of the towing vehicle 12. For example, it can be estimated whether there is still a drive reserve available to activate a dynamo mode for charging the energy storage 74. Dynamo mode is discussed below with reference to 2 explained.

2 shows a method 100 for charging an energy storage device 74 of a trailer vehicle 14 with an electric drive 72 according to an exemplary embodiment. In step 102, a charge state 104 of the energy storage 74 is recorded. The charge state 104, in particular the charge 105, is transferred to a step 106 in which it is compared with a minimum threshold value 108. The minimum threshold value 108 is adjusted in a step 111 depending on a power consumption forecast value 109. The power consumption forecast value 109 is previously determined by a control unit 54 of the trailer vehicle 14 in a step 113. Is the charger located? If 104 was below the minimum threshold 108, the next step 110 is carried out. Otherwise, after a predefined period of time has elapsed, the state of charge 104 is recorded again in step 102.

In step 110, if the state of charge 104 is below the minimum threshold 108, an operating state is estimated. To estimate the operating state in step 110, step 110 includes a step 112 in which a speed 114 of the trailer vehicle 14 is detected, a step 116 in which an acceleration 118 of the trailer vehicle 14 is detected, a step 120 in which a mass 122 of the trailer vehicle 14 is detected and a step 124 in which an inclination 126 of the trailer vehicle 14 is detected. Based on the speed 114, the acceleration 118, the mass 122 and the inclination 126, it can be determined in step 110 with an evaluation step 128, also included in step 110, in which a predetermined performance profile 130 of a primary drive 24 of a towing vehicle 12 pulling the trailer vehicle 14 is provided whether a switching process 132 or a braking process 134 with active friction brakes 22 is active and which drive reserves 136 of the primary drive 24 are available. The results of the evaluation step 128, namely whether a switching process 132 is active, whether a braking process 134 is active and which drive reserves 136 are available, are part of the estimated operating state 138. The estimated operating state 138 is fed to a step 139 in which the operating state 138 is determined as a permissible operating state 140 or as an impermissible operating state 142. In the case of an impermissible operating state 142, the operating state 138 is estimated again in step 110.

In the event that the operating state 138 corresponds to a permissible operating state 140, a dynamo mode 146 is activated in step 144. In dynamo mode 146, a power 150 or a torque 154 that is to be generated with the electric drive 72 is first determined in step 148. For this purpose, the estimated operating state 138 is fed to step 148 in order to determine the power 150 or the torque 154 depending on the estimated operating state 138. A battery state 156, which includes, for example, a battery temperature 158 and which is determined in a step 160, is additionally supplied to step 148 and is also taken into account when determining the power 150 or the torque 154. In addition, in step 162, a power consumption 164 from consumers 82 of the trailer vehicle 14 is determined and this power consumption 164 is also fed to step 148 to determine the power 150 or the torque 154. Alternatively, a predefined minimum power consumption 165 can also be supplied to step 148. In addition, step 148 is supplied with a threshold speed value 166, which is predefined in step 168.

In step 170, the drive is then controlled to generate electrical power 150 for charging the energy storage 74 or to generate a negative torque 154 with corresponding power 150. This continues until it is detected in a step 172 that a predetermined amount of energy 174 has been generated, in step 176 it is detected that a switch-off threshold 178 of the charge 105 of the energy storage 74 is reached, or an impermissible operating state 142, which is repeated regularly Step 110 is detected, in step 180 is detected. In this case, the dynamo mode 146 is deactivated in step 182.

Step 102, namely detecting the state of charge, is therefore carried out in particular periodically even after a dynamo mode 146 is activated. The operating state in step 110 is also periodically estimated, even if the dynamo mode 146 is activated. Steps 148 and 170 are also repeated regularly and so the power 150 and the torque 154 in step 148 are adapted to a changing drive reserve 136, for example. Accordingly, the power 150 is increased with increasing speed up to the threshold speed value 166; this can be done by specifying a constant torque 154. Once the threshold speed value 166 is reached, the power 150 is then kept constant.

Reference symbols (part of the description):

10

team

12

towing vehicle

14

trailer vehicle

16

drawbar

18

Axles

20

Wheels

22

Friction brakes

24

Primary drive

26

Internal combustion engine

28

Accelerator pedal position

30

accelerator

32

Brake pedal position

34

Brake pedal

36

Speed increase

38

Braking request

40

Vehicle control unit

42

Tractor vehicle brake control unit

44

bus

46

Data Connection

48

Data Connection

50

Target torque value

52

Brake control line

54

Control unit

56

Trailer brake control unit

58

Brake control pressure

60

sensor

62

steering

72

electric drive

74

Energy storage

76

Inverter

78

electric motors

80

bus

82

consumer

84

Cooling unit

85

Status signal

86

retarder

90

Accelerometer

92

Tilt sensor

94

Wheel speed sensor

96

air bellows

100

Proceedings

102

Monitor charging status

104

charging status

105

charge

106

Compare state of charge with minimum threshold

108

Minimum threshold

109

Power consumption forecast value

110

Estimate operating condition

111

Adjust minimum threshold

112

Capture speed

113

Determine power consumption forecast value

114

speed

116

Capture acceleration

118

acceleration

120

Capture mass

122

Dimensions

124

Capture tilt

126

Tilt

128

Evaluation step

130

Performance profile

132

switching process

134

Braking process

136

Drive reserves

138

estimated operating condition

139

Determine operating status

140

permissible operating condition

142

impermissible operating state

144

Enable dynamo mode

146

Dynamo mode

148

Determine power or torque

150

Performance

154

Torque

156

Battery condition

158

Battery temperature

160

Determine battery condition

162

Determine power consumption

164

Power consumption

165

Minimum power consumption

166

Threshold speed value

168

Predefine threshold speed value

170

Control drive

172

Capture predetermined amount of energy

174

predetermined amount of energy

176

Capture shutdown threshold

178

Shutdown threshold

180

Detecting impermissible operating status

182

Disable dynamo mode

Claims (15)

Method (100) for charging an energy storage device (74) of a trailer vehicle (14) with an electric drive (72), comprising the steps: - monitoring (102) a charge state (104) of the energy storage (74), - estimating (110) an operating state (138) of the towing vehicle (12) pulling the trailer vehicle (14) with a control unit (54) of the trailer vehicle (14) and - Activating (144) a dynamo mode (146) in the event that the charge state (104) indicates a charge (105) of the energy storage (74) below a minimum threshold value (108) and the operating state (138) corresponds to a permissible operating state (140), where In the dynamo mode (146), the electric drive (72) is controlled in order to provide energy for the energy storage (74). Procedure (100) according to Claim 1 , wherein the minimum threshold value (108) is constant and predefined or adjustable or a power consumption forecast value (109) is determined with the control unit (54) and the minimum threshold value (108) is automatically set by the control unit (54) depending on the power consumption forecast value (109). Procedure (100) according to Claim 1 or 2 , wherein in dynamo mode (146) the electric drive (72) is controlled by the control unit (54) in order to generate a power (150) specified by the control unit (54) of the trailer vehicle (14) and/or a power output (150) specified by the control unit (54). Trailer vehicle (14) to set the specified negative torque (154). Procedure (100) according to Claim 3 , wherein the power (150) and/or the torque (154) is/are specified by the control unit (54) depending on the operating state (138). Procedure (100) according to Claim 3 or 4 , wherein the power (150) and/or the torque (154) is/are specified by the control unit (54) in such a way that the power (150) increases with increasing speed up to a predefined threshold speed value (166), and in particular the torque ( 154) is specified constantly, with the power (150) being specified constantly from the threshold speed value (166). Method (100) according to one of the preceding claims, wherein a battery condition (156), in particular a temperature of the energy storage (74), is checked and the power or power (150) and/or the torque or torque (154) depending on the battery condition (100) 156) is/are set by the control unit (54). Method (100) according to one of the preceding claims, wherein a power consumption (164) of consumers (82), in particular comprising a cooling unit (84), of the trailer vehicle (14) is determined and the power or a power (150) at least corresponding to the power consumption (164 ) is set and/or a minimum power consumption (165), for example 20 kW or 30 kW, is set and the power (150) is set by the control unit (54) at least in accordance with the minimum power consumption (165). Method (100) according to one of the preceding claims, wherein in the event of a request for the electric drive (72), in particular by a towing vehicle brake control device (42), in the event of an activation (144) of the dynamo mode (146), the or a power (150) and/or the torque or torque (154) is/are additionally requested depending on the requirement for the electric drive (72). Method (100) according to one of the preceding claims, wherein to estimate (110) the operating state (138), the control device (54) arranged in the trailer vehicle (14) determines a speed (114) and/or an acceleration (118), an inclination (126 ) and a mass (122) of the trailer vehicle (14) is determined and the operating state (138) is estimated depending on the speed (114) and / or the acceleration (118), the inclination (126) and the mass (122). Method (100) according to one of the preceding claims, wherein the operating state (138) is additionally dependent on a power profile (130) of a primary drive (24) of the towing vehicle (12) which is learned or parameterized in the control unit (54) of the trailer vehicle (14). , which pulls the trailer vehicle (14), is determined, wherein the power profile (130) comprises at least one maximum power value of the primary drive (24). Method (100) according to one of the preceding claims, wherein estimating the operating state (138) comprises recognizing an active switching process (132) and/or an active braking process (134) of the friction brakes (22), wherein during a displayed active switching process ( 132) or an active braking process (134) of the friction brakes (22) prevents deactivation (182) and/or activation (144) of the dynamo mode (146). Method (100) according to one of the preceding claims, wherein the dynamo mode (146) is deactivated (182) when a predefined or parameterized switch-off threshold (178) is reached when a predefined or parameterized amount of energy (174) was stored in the energy storage (74). and/or the operating status (138) is recognized as an impermissible operating state (142). Control device (54), in particular brake control device (56), for a trailer vehicle (14), the control device (54) being set up to provide an electric drive (72) according to a method (100) according to one of Claims 1 until 12 head for. Trailer vehicle (14) with a control unit (54), in particular brake control unit (56). Claim 13 and an electric drive (72). Team (10) with a towing vehicle (12) and a trailer vehicle (14). Claim 14 .

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