Method, powertrain, vehicle, computer program and computer readable medium for controlling a vehicle associated with a downhill slope

Abstract

The present invention relates to a method for controlling a vehicle (1) associated with a downhill slope (200), the vehicle (1) having a powertrain (3), the powertrain comprising: a drive unit (2), the drive unit being configured to provide propulsion power; an auxiliary braking device (4); and a first cooling circuit (10), the first cooling circuit comprising a first coolant (12); wherein the drive unit (2) and the auxiliary braking device (4) are arranged to be selectively connected or disconnected from the first cooling circuit (10), wherein the drive unit (10) has a first maximum temperature and the auxiliary braking device (4) has a second maximum temperature higher than the first maximum temperature, the method comprising: when the vehicle (1) is approaching an upcoming downhill slope (200) that meets a predetermined criterion, controlling (s101) the drive unit (2) to reduce the provided propulsion power. The method comprises disconnecting the drive unit (2) from the first cooling circuit (10) (s102); connecting the auxiliary braking device (4) to the first cooling circuit (10) (s103); and controlling (s104) the auxiliary braking device (4) to brake the vehicle (1) downward along the downhill slope (200). The invention also relates to a powertrain (3) and a vehicle (1) comprising such a powertrain. The invention also relates to a computer program and a computer-readable medium for executing the method.

Description

Technical Field

[0001] The invention relates to a method for controlling a vehicle associated with a downhill slope. The invention also relates to a powertrain and a vehicle comprising such a powertrain. The invention also relates to a computer program and a computer readable medium for executing said method. Background Art

[0002] Vehicles with other drive units besides internal combustion engines are becoming more and more common. Hybrid vehicles including an internal combustion engine and an electric motor / motor have been known for some time, but companies have been looking for other solutions to reduce the impact on the environment. Such other solutions can be fuel cell devices.

[0003] The cooling of the fuel cell is crucial, and the maximum temperature of the fuel cell is relatively low. This means that the coolant that cools the fuel cell must have a relatively low temperature. The auxiliary brake in a fuel cell vehicle may have a higher maximum temperature than the fuel cell. The auxiliary brake is generally referred to as a brake that is different from the main braking system (wheel brakes). The auxiliary brake in a fuel cell vehicle can be a retarder, a brake resistor, an air compression brake, or any other auxiliary braking system. In order to maximize the performance of the auxiliary brake, the temperature of the coolant should be as close as possible to the maximum temperature of the auxiliary brake. Therefore, the fuel cell and the auxiliary brake require separate cooling circuits. Any vehicle with a drive unit with a lower maximum temperature than the auxiliary brake may require a separate cooling circuit.

[0004] Document US2010273079 A1 discloses a fuel cell transmission for a motor vehicle and a fuel cell cooling assembly comprising several cooling units for cooling different fuel cell units. Summary of the invention

[0005] One object of the invention is to achieve a novel and advantageous method for controlling a vehicle associated with a downhill slope, wherein the drive unit of the vehicle has a lower maximum temperature than the auxiliary brakes. Another object of the invention is to achieve a novel and advantageous method for controlling a vehicle associated with a downhill slope, which increases the performance of the auxiliary brakes when necessary. Another object of the invention is to achieve a novel and advantageous powertrain, vehicle, computer program and computer readable medium.

[0006] The objects mentioned herein are achieved by a method, a power train, a vehicle, a computer program and a computer readable medium according to the independent claims.

[0007] Therefore, according to one aspect of the present invention, there is provided a method for controlling a vehicle associated with a downhill slope, performed by a control device. The vehicle has a powertrain, the powertrain comprising: a drive unit, the drive unit being configured to provide propulsion power; an auxiliary braking device; and a first cooling circuit, the first cooling circuit comprising a first coolant; wherein the drive unit and the auxiliary braking device are arranged to be selectively connected or disconnected from the first cooling circuit, wherein the drive unit has a first maximum temperature and the auxiliary braking device has a second maximum temperature higher than the first maximum temperature. The method comprises: when the vehicle is approaching an upcoming downhill slope that meets a predetermined criterion, controlling the drive unit to reduce the propulsion power provided; disconnecting the drive unit from the first cooling circuit; connecting the auxiliary braking device to the first cooling circuit; and controlling the auxiliary braking device to brake the vehicle downward along the downhill slope.

[0008] According to another aspect of the present invention, a powertrain for a vehicle is provided. The powertrain comprises: a drive unit configured to provide propulsion power; an auxiliary brake device; and a first cooling circuit comprising a first coolant; wherein the drive unit and the auxiliary brake device are arranged to be selectively connected or disconnected from the first cooling circuit, wherein the drive unit has a first maximum temperature and the auxiliary brake device has a second maximum temperature higher than the first maximum temperature. The powertrain also comprises a control device configured to: when the vehicle is approaching an upcoming downhill slope that meets a predetermined criterion, control the drive unit to reduce the propulsion power provided; disconnect the drive unit from the first cooling circuit; connect the auxiliary brake device to the first cooling circuit; and control the auxiliary brake device to brake the vehicle down the downhill slope.

[0009] According to another aspect of the present invention, a vehicle is provided, comprising a powertrain as disclosed herein.

[0010] The vehicle may include multiple cooling circuits for cooling various components in the vehicle. The drive unit, the auxiliary brake or any other object of the vehicle has a maximum temperature, which means that the temperature of the object should not be higher than the maximum temperature, otherwise the object may fail. Therefore, the temperature of the coolant cooling the object should be lower than the maximum temperature of the object so that the object can be cooled and the maximum temperature can be maintained. In the case where the drive unit and the auxiliary brake device are connected to the same cooling circuit, the vehicle with the drive unit and the auxiliary brake device having different maximum temperatures is limited to the lowest maximum temperature. Generally, heat removal depends on the temperature difference between the coolant and the ambient air. As the coolant temperature increases, more heat will be removed. According to the present invention, the drive unit has a lower maximum temperature than the auxiliary brake device. This means that when the drive unit and the auxiliary brake device are connected to the first cooling circuit, the temperature of the first coolant should not have a first maximum temperature higher than the drive unit. However, this also means that the performance of the auxiliary brake device cannot be optimized because the auxiliary brake device can only be used for temperatures lower than its second maximum temperature. By configuring the powertrain according to the present invention so that the drive unit and the auxiliary brake device can be selectively connected to or disconnected from the first cooling circuit, the performance of the auxiliary brake device can also be optimized, although the drive unit and the auxiliary brake device can be connected to the same cooling circuit. Therefore, when the vehicle is approaching a certain downhill slope that meets the predetermined criteria, the drive unit is controlled so that it provides a reduced amount of propulsion power. In this way, the drive unit will require less cooling. The drive unit can therefore be disconnected from the first cooling circuit without the risk of overheating. Then, it is ensured that the auxiliary braking device is connected to the first cooling circuit and the auxiliary braking device is controlled to brake the vehicle downward along the downhill slope. When the auxiliary braking device is activated, the auxiliary braking device needs to be cooled. Therefore, the auxiliary braking device must first be connected to the first cooling circuit. By disconnecting the drive unit from the first cooling circuit, the first coolant is no longer limited to the first maximum temperature of the drive unit, but can have a temperature similar to the second maximum temperature of the auxiliary braking device. Therefore, the auxiliary braking device can be operated to a higher temperature and the performance of the auxiliary braking device can be optimized.

[0011] Other objects, advantages and novel features of the present invention will become apparent to those skilled in the art from the following details and also by putting the present invention into practice. Although examples of the present invention are described below, it should be noted that they are not limited to the specific details described. Experts who can obtain the teachings of this article will recognize further applications, modifications and incorporations in other fields within the scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] For a better understanding of the present invention and its other objects and advantages, the following detailed description should be read in conjunction with the accompanying Figure 1 In the drawings, like reference numerals denote similar items in the various figures, and in the drawings:

[0013] Figure 1 schematically illustrates a side view of a vehicle according to an example;

[0014] Figure 2 schematically illustrates details of a powertrain of a vehicle according to an example;

[0015] Figure 3 schematically illustrates details of a powertrain of a vehicle according to an example;

[0016] Figure 4 schematically illustrates details of a powertrain of a vehicle according to an example;

[0017] Figure 5 schematically illustrates details of a powertrain of a vehicle according to an example;

[0018] Figure 6 schematically illustrates a block diagram of a method for controlling a vehicle associated with an upcoming downhill grade according to an example; and

[0019] Figure 7 A control device or a computer according to an example is schematically shown. DETAILED DESCRIPTION

[0020] Cooling of components in a vehicle is crucial for its performance and durability. In order to ensure cooling of the drive unit and to be able to improve the performance of the auxiliary brakes, a method, a powertrain and a vehicle according to the present disclosure have been developed.

[0021] Therefore, according to one aspect of the present disclosure, a method for controlling a vehicle associated with a downhill slope, performed by a control device, is provided. The vehicle has a powertrain, the powertrain comprising: a drive unit, the drive unit being configured to provide propulsion power; an auxiliary braking device; and a first cooling circuit, the first cooling circuit comprising a first coolant; wherein the drive unit and the auxiliary braking device are arranged to be selectively connected or disconnected from the first cooling circuit, wherein the drive unit has a first maximum temperature and the auxiliary braking device has a second maximum temperature higher than the first maximum temperature. The method comprises: when the vehicle is approaching an upcoming downhill slope that meets a predetermined criterion, controlling the drive unit to reduce the propulsion power provided; disconnecting the drive unit from the first cooling circuit; connecting the auxiliary braking device to the first cooling circuit; and controlling the auxiliary braking device to brake the vehicle downward along the downhill slope.

[0022] A drive unit with a first maximum temperature means that the drive unit is configured to work normally up to the first maximum temperature. Similarly, an auxiliary brake device with a second maximum temperature means that the auxiliary brake device is configured to work normally up to the second maximum temperature. In order to maintain the temperature below the maximum temperature during the operation of the drive unit and the auxiliary brake device, respectively, the drive unit and the auxiliary brake device must be cooled by the first cooling circuit and the first coolant. In addition, the temperature of the first coolant should be lower than the maximum temperature of the drive unit and the auxiliary brake device, respectively. The first maximum temperature of the drive unit may be between 70-80 degrees Celsius. The second maximum temperature of the auxiliary brake device may be between 100-120 degrees Celsius. Therefore, if the drive unit and the auxiliary brake device are both connected to the first cooling circuit, the temperature of the first coolant is limited by the first maximum temperature of the drive unit (should be lower than the first maximum temperature) because this temperature is lower than the second maximum temperature of the auxiliary brake device. Then, the auxiliary brake device will not operate optimally. When the vehicle is traveling downhill, the auxiliary brake may be required to typically brake the vehicle to reduce the wear of the wheel brakes. Depending on the downhill, the best performance of the auxiliary brake device may be required. Therefore, when the vehicle is approaching a downhill slope that meets a certain criterion, the drive unit is disconnected from the first cooling circuit so that the temperature of the first coolant is instead limited by the second maximum temperature of the auxiliary brake device, and the performance of the auxiliary brake device can thereby be improved. It should be understood that there may be a delay before disconnecting the drive unit from the first cooling circuit in order to remove any residual heat remaining in the drive unit. In addition, in the case where the maximum temperature of the auxiliary brake is lower than the maximum temperature of the drive unit, a similar solution can be used when the auxiliary brake device is disconnected from the first cooling circuit to optimize the performance of the drive unit.

[0023] The first cooling circuit may include a first radiator and a first fan. The first radiator may be arranged to be in fluid communication with the drive unit and the auxiliary brake device. Therefore, the same first radiator is arranged to cool both the drive unit and the auxiliary brake device. The first cooling circuit may also include a first pump arranged to be in fluid communication with the drive unit and / or a second pump arranged to be in fluid communication with the auxiliary brake device. The first cooling circuit may also include a reservoir for accommodating the first coolant. According to a conventional cooling circuit, the first cooling circuit may also include a conduit / channel / pipeline, which is used to flow the coolant between various components. The drive unit and the auxiliary brake device are arranged to be selectively connected or disconnected from the first cooling circuit, which means that the drive unit and the auxiliary brake device are arranged to be selectively connected or disconnected from the first radiator. Therefore, the drive unit and the auxiliary brake device are arranged to be cooled by the first cooling circuit, but are arranged to be selectively connected or disconnected from the first radiator.

[0024] The drive unit may include a fuel cell device or an electric motor. The auxiliary brake device is a brake device in addition to the main brake system of the vehicle. The main brake system may include conventional wheel brakes. The auxiliary brake device may include a retarder, a brake resistor, an air compression brake or any other auxiliary brake system.

[0025] When the vehicle is approaching an upcoming downhill slope that meets predetermined criteria, controlling the drive unit to reduce the provided propulsion power may include reducing the provided propulsion power to substantially zero. Thus, the drive unit may be deactivated. By reducing the work of the drive unit, the drive unit requires less cooling. Today, vehicles typically include different systems for reducing costs, reducing fuel consumption, improving driving performance, etc. A common strategy is to reduce the vehicle speed before reaching the top of the downhill slope and let the vehicle recover speed while driving along the downhill slope, thereby converting potential energy into kinetic energy. Therefore, reducing the provided propulsion power by the drive unit may be performed at a certain distance before reaching the top of the downhill slope.

[0026] The method may include identifying an upcoming downhill slope that meets a predetermined criterion. The control device may collect data related to the surrounding environment and the upcoming downhill slope from various vehicle sensors, vehicle systems, navigation systems and map data. The control device may also identify an upcoming downhill slope that meets the predetermined criterion based on the collected data. According to an example, the predetermined criterion includes that the upcoming downhill slope has a certain length and / or a certain gradient. When the downhill slope has a certain length and / or gradient, it may be necessary to brake the vehicle to avoid vehicle acceleration. However, acceleration also depends on vehicle weight. Therefore, the predetermined criterion related to the downhill slope may depend on vehicle weight. Generally, the higher the downhill slope or the greater the gradient of the downhill slope, the greater the possibility that the auxiliary braking device is required to brake the vehicle down along the downhill slope. Therefore, the predetermined criterion may include that the height of the downhill slope is higher than a predetermined threshold and / or the gradient of the downhill slope is greater than a predetermined threshold. The predetermined criterion may be stored in the control device. The current vehicle weight may also be stored in the control device. The control device may include a list of predetermined criteria associated with different vehicle weights stored in a database. Therefore, the control device may compare the collected data related to the downhill slope with the list to determine whether the criteria are met. When traveling along a downhill slope, the vehicle is usually operated to maintain a desired vehicle speed or avoid a runaway condition. Braking the vehicle may be performed by using the vehicle's main braking system and / or by using an auxiliary braking device. When the auxiliary braking device is used, cooling is required and to be able to optimize the performance of the auxiliary braking device, the drive unit may be disconnected from the first cooling circuit. Thus, the predetermined criterion may be that the downhill slope is configured such that the auxiliary braking device is required to brake the vehicle going down the downhill slope in order to avoid uncontrolled behavior or to maintain a desired vehicle speed. Thus, the method steps may only be performed when the vehicle is approaching a downhill slope where the auxiliary braking device is required to brake the vehicle.

[0027] According to an example of the present disclosure, disconnecting the drive unit from the first cooling circuit includes controlling a first valve device. The first cooling circuit may therefore include a first valve device arranged to be in fluid communication with the drive unit. The first valve device may be controlled to different states, and thereby disconnect or connect the drive unit from the first cooling circuit / first radiator. When the drive unit is connected to the first cooling circuit, the coolant is allowed to flow through the drive unit, flow to the first radiator via the first valve device and return to the drive unit. Therefore, when the drive unit is connected to the first cooling circuit, the first coolant leaving the drive unit is directed to the first radiator via the first valve device and then returned to the drive unit. This may be referred to as a drive unit circuit. The powertrain may also include a bypass circuit. The bypass circuit may be arranged to be in fluid communication with the first valve device and the drive unit, so that the first coolant can be selectively directed to the bypass circuit instead of to the first radiator of the first cooling circuit. Therefore, when the first valve device is controlled to disconnect the drive unit from the first cooling circuit, the first coolant is allowed to flow through the drive unit, flow to the bypass circuit via the first valve device and return to the drive unit. Thus, disconnecting the drive unit from the first cooling circuit comprises controlling the first valve arrangement such that the first coolant bypasses the first radiator.

[0028] The method may include ensuring that the auxiliary brake device is connected to the first cooling circuit. When starting the method, both the drive unit and the auxiliary brake device may be connected to the first cooling circuit. Connecting the auxiliary brake device to the first cooling circuit may include controlling a second valve device. The first cooling circuit may therefore include a second valve device arranged to be in fluid communication with the auxiliary brake device. The second valve device may be controlled to different states and thereby disconnect or connect the auxiliary brake device to the first cooling circuit. When the auxiliary brake device is connected to the first cooling circuit, the first coolant is allowed to flow through the auxiliary brake device via the second valve device, flow to the first radiator and return to the auxiliary brake device. This may be referred to as an auxiliary brake circuit. When the second valve device is controlled to disconnect the auxiliary brake device from the first cooling circuit, the first coolant is not allowed to flow through the auxiliary brake device.

[0029] Alternatively, connecting the auxiliary brake to the first cooling circuit may include activating the auxiliary brake device. Thus, the powertrain may be configured such that when the auxiliary brake device is activated, the auxiliary brake device is automatically connected to the first cooling circuit. Similarly, when the auxiliary brake device is no longer used, the auxiliary brake device may be automatically disconnected from the first cooling circuit. Thus, the auxiliary brake device connected to the first cooling circuit may mean that the first coolant is allowed to flow through the auxiliary brake device.

[0030] The first cooling circuit may include / divide into a drive unit circuit and an auxiliary brake circuit. The drive unit circuit may include a first pump and the auxiliary brake circuit may include a second pump. The first pump and the second pump are arranged to enable coolant to flow through the drive unit and the auxiliary brake, respectively.

[0031] According to an example, the method further comprises controlling the powertrain so that propulsion power is provided by means of an energy storage unit of the powertrain before the vehicle has reached the top of the downhill slope. It should be understood that a vehicle comprising a fuel cell also comprises a motor for propelling the vehicle. A vehicle comprising a fuel cell generally comprises an energy storage unit, such as a battery. Typically, in the case where the fuel cell produces too much energy, the energy storage unit will store excess energy, and in the case where the fuel cell produces too little energy, the energy storage unit can provide energy to the motor. As previously described, it is common to reduce the vehicle speed before the top of the downhill slope. However, in order to be able to disconnect the drive unit from the first cooling circuit in a safe manner, the temperature of the drive unit can be greatly reduced before the drive unit is disconnected from the first cooling circuit. Therefore, the drive unit can be controlled to reduce the propulsion power at a distance from the top of the downhill slope to be sufficient to cool the drive unit and disconnect the drive unit. However, the vehicle driver may not be aware of reducing the vehicle speed too much before reaching the top of the downhill slope, so the energy storage unit can be used to provide energy to the motor and thereby provide propulsion power. In this way, the vehicle speed is not affected by the reduction in propulsion power provided by the drive unit. Therefore, the method may include controlling the energy supply to the motor so that the energy is provided by the energy storage unit rather than the drive unit. Due to the reduction of the propulsion power provided by the drive unit, the energy can be automatically provided by the energy storage unit. Therefore, controlling the powertrain to provide propulsion power with the aid of the energy storage unit can be automatically performed by controlling the drive unit to reduce the propulsion power provided. However, depending on the configuration of the powertrain, it may be necessary to actively control the powertrain to provide propulsion power with the aid of the energy storage unit. Controlling the powertrain to provide propulsion power with the aid of the energy storage unit before the vehicle has reached the top of the downhill slope may mean controlling the powertrain to provide propulsion power with the aid of the energy storage unit until the vehicle has reached the top of the downhill slope, or at least for a period of time before the vehicle has reached the top of the downhill slope. When operating the vehicle along the downhill slope, the energy storage unit can instead be charged by converting kinetic energy into electrical energy.

[0032] Furthermore, the method may include connecting the drive unit to the first cooling circuit when the temperature of the first coolant is lower than the first maximum temperature of the drive unit. At the bottom of the downhill slope, the power of the auxiliary brake device will decrease and the temperature of the first coolant will decrease rapidly. When the temperature of the first coolant is lower than the first maximum temperature of the drive unit, the drive unit may be cooled by the first cooling circuit and maintain its first maximum temperature. Therefore, it is safe to connect the drive unit to the first cooling circuit again.

[0033] Connecting the drive unit to the first cooling circuit may include controlling the first valve device such that the first coolant flowing through the drive unit is allowed to flow through the first radiator.

[0034] The method may further comprise disconnecting the auxiliary braking device from the first cooling circuit when the auxiliary braking device is no longer in operation. Disconnecting the auxiliary braking device from the first cooling circuit may comprise controlling the second valve arrangement, or it may comprise deactivating the auxiliary braking device whereby it is automatically disconnected from the first cooling circuit.

[0035] According to an example, the method further comprises connecting an auxiliary cooling device of the powertrain to the drive unit when the drive unit is disconnected from the first cooling circuit. When the drive unit is disconnected from the first cooling circuit, it may still require some cooling to remove heat. However, since the drive unit is controlled to provide less propulsion power, the need for cooling will be less. By connecting the drive unit to the auxiliary cooling device, the required cooling of the drive unit can be obtained while cooling the auxiliary brakes by means of the first cooling circuit.

[0036] The auxiliary cooling device may include an auxiliary radiator arranged to be in fluid communication with the drive unit. The auxiliary radiator is suitably of smaller size and capacity than the first radiator of the first cooling circuit. The auxiliary cooling device may also include an auxiliary fan arranged in association with the auxiliary radiator. The auxiliary radiator may be arranged in a bypass circuit or in any other convenient manner. The auxiliary radiator may, for example, be arranged before the first valve device. The auxiliary cooling device may thus be connected to the drive unit by controlling the first valve device. Therefore, by controlling the first valve device, the first coolant leaving the drive unit will be directed to the bypass circuit and flow to the drive unit through the auxiliary radiator. Therefore, the first coolant in the bypass circuit will be cooled by the auxiliary radiator and will cool the drive unit.

[0037] According to another example, the auxiliary cooling device includes a heat exchanger arranged to be in fluid communication with the drive unit and a second cooling circuit having a second cooling medium. The second cooling circuit is appropriately colder than the first cooling circuit. Therefore, the temperature of the second cooling medium is lower than the first coolant in the first cooling circuit. The heat exchanger can be arranged in a bypass circuit or before the first valve device. The second cooling circuit can be arranged to be in fluid communication with the heat exchanger by controlling the third valve device. Therefore, by controlling the third valve device, the second cooling medium can be allowed to flow through the heat exchanger and thus cool the first coolant in fluid communication with the heat exchanger. The second cooling circuit can be a cooling circuit for power electronics of the vehicle. Alternatively, the second cooling circuit can be a cooling circuit for motor oil or coolant, battery cooling or the like. It should be understood that as long as the second cooling medium can selectively flow through the heat exchanger and thereby cool the drive unit, how the second cooling circuit is constructed or how it is connected to the heat exchanger is not critical to the function of the present disclosure.

[0038] The auxiliary cooling device may alternatively include a second cooling circuit having a second coolant, the second cooling circuit being arranged to be in fluid communication with the drive unit by controlling the fourth valve device so that the first coolant is mixed with the second coolant. The auxiliary cooling device may thus be connected to the drive unit by controlling the fourth valve device. The second cooling circuit may be arranged to be in fluid communication with a bypass circuit upstream of the drive unit. When the fourth valve device is controlled to an open stage, the second coolant from the second cooling circuit will be mixed with the first coolant in the bypass circuit. The second coolant appropriately has a lower temperature than the first coolant in the bypass circuit. Therefore, the mixed coolant passing through the drive unit will have a lower temperature, and therefore the drive unit will be cooled. The second cooling circuit may be a cooling circuit for power electronics of the vehicle. Alternatively, the second cooling circuit may be a cooling circuit for a battery. The same amount of fluid entering the bypass circuit from the second cooling circuit should be removed / the same amount of fluid entering the bypass circuit from the second cooling circuit should be returned to the second cooling circuit from the bypass circuit. Therefore, some of the mixed coolant may be returned to the second cooling circuit before entering the drive unit. Alternatively, the mixed coolant downstream / after the drive unit may be returned to the second cooling circuit. It should be understood that exactly how the second cooling circuit is constructed or connected to the drive unit / bypass circuit is not critical to the functionality of the present disclosure, as long as the second coolant can selectively be mixed with the first coolant to cool the drive unit.

[0039] According to another aspect of the present disclosure, a powertrain for a vehicle is provided. The powertrain includes: a drive unit configured to provide propulsion power; an auxiliary brake device; and a first cooling circuit, the first cooling circuit including a first coolant; wherein the drive unit and the auxiliary brake device are arranged to selectively connect or disconnect with the first cooling circuit, wherein the drive unit has a first maximum temperature and the auxiliary brake device has a second maximum temperature higher than the first maximum temperature. The powertrain also includes a control device configured to reduce the propulsion power provided when the vehicle is approaching an upcoming downhill slope that meets a predetermined criterion; disconnect the drive unit from the first cooling circuit; connect the auxiliary brake device to the first cooling circuit; and control the auxiliary brake device to brake the vehicle down the downhill slope.

[0040] According to another aspect of the present disclosure, a control device configured to control a vehicle associated with a downhill slope is provided. It should be understood that all embodiments described in the method aspect of the present disclosure performed by the control device are also applicable to the control device aspect and powertrain aspect of the present disclosure. That is, the control device can be configured to perform any step of the method according to the various examples described above.

[0041] Thus, the control device may be configured to disconnect the drive unit from the first cooling circuit by controlling the first valve device. The control device may be configured to connect the auxiliary braking device to the first cooling circuit by controlling the second valve device. The control device may be configured to control the powertrain to provide propulsion power by means of the energy storage unit of the powertrain before the vehicle has reached the top of an upcoming downhill slope. Furthermore, the control device may be configured to connect the drive unit to the first cooling circuit when the temperature of the first coolant is lower than the maximum temperature of the drive unit. The control device may also be configured to connect the auxiliary cooling device to the drive unit when the drive unit is disconnected from the first cooling circuit.

[0042] It will be appreciated that the control device for performing the disclosed method may be implemented as a separate entity or distributed in two or more physical entities. The control device may include one or more control units and / or computers. Thus, the control device may be implemented or realized by a control device including a processor and a memory, the memory including instructions that, when executed by the processor, cause the control device to perform the method steps disclosed herein. The control device is included in a vehicle.

[0043] According to another aspect of the present disclosure, a vehicle is provided. The vehicle comprises a powertrain and thus comprises a control device as disclosed herein.

[0044] The present disclosure will now be further described with reference to the accompanying drawings.

[0045] Figure 1 A side view of a vehicle 1 approaching a downhill slope 200 according to an example is schematically shown. The exemplary vehicle 1 may be a heavy vehicle of a truck, bus or similar vehicle shape. The vehicle 1 has a powertrain 3 including a drive unit 2, an auxiliary brake device 4 and a first cooling circuit 10 including a first coolant (not shown). The downhill slope 200 has a top / starting point 210 and a bottom / end point 220. Reference Figure 2-5 The powertrain 3 is further described.

[0046] Figure 2 Schematically shows details of a powertrain 3 for a vehicle according to an example. The powertrain 3 may include Figure 1 In the disclosed vehicle 1. As disclosed above, the powertrain 3 includes a drive unit 2, an auxiliary brake device 4 and a first cooling circuit 10 including a first coolant 12. The flow direction of the first coolant 12 in the first cooling circuit 10 is shown by the arrows in the figure. The drive unit 2 and the auxiliary brake device 4 are arranged to be selectively connected or disconnected from the first cooling circuit 10. The drive unit 2 has a first maximum temperature, and the auxiliary brake device 4 has a second maximum temperature. The second maximum temperature may be higher than the first maximum temperature. The powertrain 3 also includes a control device 100. The first cooling circuit 10 includes a reservoir 14 for the first coolant 12.

[0047] The first cooling circuit 10 comprises a first radiator 20. The first cooling circuit 10 may further comprise a first fan 22 arranged in association with the first radiator 20. The first radiator 20 may be arranged in fluid communication with the drive unit 2 and the auxiliary brake device 4. The first cooling circuit 10 may further comprise a first pump 30 arranged in fluid communication with the drive unit 2 and / or a second pump 32 arranged in fluid communication with the auxiliary brake device 4.

[0048] The first cooling circuit 10 may include a first valve device 40 arranged in fluid communication with the drive unit 2. The first valve device 40 may be controllable to different states and thereby disconnect or connect the drive unit 2 from the first cooling circuit 10 and more specifically the first radiator 20. The powertrain 3 may also include a bypass circuit 50. The bypass circuit 50 may be arranged in fluid communication with the first valve device 40 and the drive unit 2 so that the first coolant 12 may be selectively directed to the bypass circuit 50 instead of being directed to the first radiator 20 of the first cooling circuit 10. When the first valve device 40 is controlled to disconnect the drive unit 2 from the first radiator 20, the first coolant 12 is allowed to flow through the drive unit 2, via the first valve device 40 to the bypass circuit 50 and back to the drive unit 2. When the drive unit is disconnected from the first radiator 20, the first valve device 40 is controlled to cause the first coolant 12 to bypass the first radiator 20. When the drive unit 2 is connected to the first radiator 20 , the first coolant 12 is allowed to flow through the drive unit 2 , to the first radiator 20 via the first valve device 40 and back to the drive unit 2 .

[0049] The first cooling circuit 10 may further include a second valve device 60 arranged to be in fluid communication with the auxiliary brake device 4. The second valve device 60 may be controlled to different states to disconnect or connect the auxiliary brake device 4 to the first radiator 20. The second valve device 60 may include a one-way valve, a check valve or the like. When the auxiliary brake device 4 is connected to the first radiator 20, the first coolant 12 is allowed to flow through the auxiliary brake device 4 via the second valve device 60, flow to the first radiator 20 and return to the auxiliary brake device 4. When the auxiliary brake device 4 is disconnected from the first radiator 20, the second valve device 60 may prevent the first coolant 12 from flowing through the auxiliary brake device 4.

[0050] The powertrain 3 may further include an energy storage unit 300 configured to selectively provide energy / propulsion power. The energy storage unit 300 may include a battery.

[0051] The control device 100 of the powertrain 3 may be configured to control the drive unit 2 to reduce the provided propulsion power when the vehicle 1 is approaching an upcoming downhill slope 200 that meets a predetermined criterion. The control device 100 may also be configured to disconnect the drive unit 2 from the first cooling circuit 10, connect the auxiliary braking device 4 to the first cooling circuit 10, and control the auxiliary braking device 4 to brake the vehicle 1 down the downhill slope 200.

[0052] The control device 100 may also be configured to identify an upcoming downhill slope 200 that meets a predetermined criterion. The control device 100 may be configured to collect data related to the downhill slope 200 from various vehicle sensors (not shown), vehicle systems (not shown), navigation systems (not shown), and map data. The control device 100 may also be configured to identify an upcoming downhill slope 200 that meets a predetermined criterion based on the collected data. According to an example, the predetermined criterion includes that the upcoming downhill slope 200 has a certain length and / or a certain gradient. The length of the downhill slope 200 may be defined as the distance between the top 210 of the downhill slope and the bottom 220 of the downhill slope. The predetermined criterion may be that the downhill slope 200 is constructed so that the auxiliary braking device 4 is required to brake the vehicle 1 going down the downhill slope 200. The predetermined criterion may be stored in the control device 100. The vehicle weight may also be stored in the control device 100. The control device 100 may include a list of predetermined criteria associated with different vehicle weights stored in a database. The control device 100 may therefore be configured to compare the collected data related to the downhill slope 200 with the list to determine whether the criterion is met. The control device 100 may be configured to ensure that the auxiliary brake device 4 is connected to the first cooling circuit 10 .

[0053] The control device 100 may be configured to disconnect the drive unit 2 from the first cooling circuit 10 / first radiator 20 by controlling the first valve device 40. The control device 100 may be configured to connect the auxiliary brake device 4 to the first cooling circuit 10 by controlling the second valve device 60. The control device 100 may be configured to control the powertrain 3 to provide propulsion energy by means of the energy storage unit 300 before the vehicle 1 has reached the top 210 of the upcoming downhill slope 200. Furthermore, the control device 100 may be configured to connect the drive unit 2 to the first cooling circuit 10 when the temperature of the first coolant 12 is below a first maximum temperature of the drive unit 2.

[0054] Figure 3 Schematically shows details of a powertrain 3 for a vehicle according to an example. The powertrain 3 may include Figure 1 In the disclosed vehicle 1, the powertrain 3 may be as follows Figure 2 The disclosed configuration.

[0055] In this example, the powertrain 3 further comprises an auxiliary cooling device 70. The auxiliary cooling device 70 may be arranged to selectively cool the drive unit 2 when the drive unit 2 is disconnected from the first cooling circuit 10. Therefore, the control device 100 may be configured to connect the auxiliary cooling device 70 to the drive unit 2 when the drive unit 2 is disconnected from the first cooling circuit 10. The auxiliary cooling device 70 may include an auxiliary radiator 72 arranged to be in fluid communication with the drive unit 2. The auxiliary radiator 72 suitably has a smaller size and capacity than the first radiator 20 of the first cooling circuit 10. The auxiliary cooling device 70 may also include an auxiliary fan 74 arranged in association with the auxiliary radiator 72. The auxiliary radiator 72 may be arranged in the bypass circuit 50. The auxiliary cooling device 70 may thus be connected to the drive unit 2 by controlling the first valve device 40. Therefore, by controlling the first valve device 40, the first coolant 12 leaving the drive unit 2 will be directed to the bypass circuit 50 and flow to the drive unit 2 through the auxiliary radiator 72. Therefore, the first coolant 12 in the bypass loop 50 will be cooled by the auxiliary radiator 72 , and will cool the drive unit 2 .

[0056] Figure 4 Schematically shows details of a powertrain 3 for a vehicle according to an example. The powertrain 3 may include Figure 1 In the disclosed vehicle 1, the powertrain 3 may be as follows Figure 2 The disclosed configuration.

[0057] In this example, the powertrain 3 also includes an auxiliary cooling device 70. The auxiliary cooling device 70 may be arranged to selectively cool the drive unit 2 when the drive unit 2 is disconnected from the first cooling circuit 10. Therefore, the control device 100 may be configured to connect the auxiliary cooling device 70 to the drive unit 2 when the drive unit 2 is disconnected from the first cooling circuit 10. The auxiliary cooling device 70 includes a heat exchanger 76 arranged to be in fluid communication with the drive unit 2 and a second cooling circuit 78 having a second cooling medium 77. The second cooling circuit 78 is appropriately cooler than the first cooling circuit 10. Therefore, the second cooling medium 77 has a lower temperature than the first coolant 12 in the first cooling circuit 10. The second cooling circuit 78 may include a pump and other components, but is not part of the present invention itself and is therefore shown in dotted lines. The heat exchanger 76 may be arranged in a bypass circuit. The second cooling circuit 78 may be arranged to be in fluid communication with the heat exchanger 76 by controlling the third valve device 80. The auxiliary cooling device 70 may therefore include the third valve device 80. By controlling the third valve device 80, the second cooling medium 77 may be allowed to flow through the heat exchanger 76 and thus cool the first coolant 12 in fluid communication with the heat exchanger 76. The first coolant 12 in the bypass circuit 50 will thereby be cooled by the second cooling circuit 78 and will cool the drive unit 2. The second cooling circuit 78 may be a cooling circuit for power electronics of the vehicle 1.

[0058] Figure 5 Schematically shows details of a powertrain 3 for a vehicle according to an example. The powertrain 3 may include Figure 1 In the disclosed vehicle 1, the powertrain 3 may be as follows Figure 2 The disclosed configuration.

[0059] In this example, the powertrain 3 further comprises an auxiliary cooling device 70. The auxiliary cooling device 70 may be arranged to selectively cool the drive unit 2 when the drive unit 2 is disconnected from the first cooling circuit 10. Therefore, the control device 100 may be configured to connect the auxiliary cooling device 70 to the drive unit 2 when the drive unit 2 is disconnected from the first cooling circuit 10. The auxiliary cooling device 70 comprises a second cooling circuit 78 having a second coolant 77', which is arranged to be in fluid communication with the drive unit 2 by controlling the fourth valve device 90 so that the first coolant 12 is mixed with the second coolant 77'. The auxiliary cooling device 70 may thus be connected to the drive unit 2 by controlling the fourth valve device 80. The second cooling circuit 78 may be arranged to be in fluid communication with the bypass circuit 50 upstream of the drive unit 2. When the fourth valve device 80 is controlled to the open stage, the second coolant 77' from the second cooling circuit 78 will be mixed with the first coolant 12 in the bypass circuit 50. The second coolant 77' suitably has a lower temperature than the first coolant 12 in the bypass circuit 50. Therefore, the mixed coolant entering the drive unit 2 will have a lower temperature, so the drive unit 2 will be cooled. The second cooling circuit 78 may be a cooling circuit for the power electronics of the vehicle 1. The second cooling circuit 78 may include a pump and other components, but is not part of the present invention per se and is therefore shown with dashed lines. Before entering the drive unit 2, some of the mixed coolant may be returned to the second cooling circuit 78. Alternatively, after leaving the drive unit 2, some of the mixed coolant is returned to the second cooling circuit 78. This example is shown with dashed lines in the figure.

[0060] Figure 6 A block diagram of a method for controlling a vehicle associated with a downhill slope according to an example is schematically shown. The method involves Figure 1 The disclosed vehicle and Figure 2 , 3 , 4 or 5. The method is as follows Figure 2-5 The disclosed control device 100 performs.

[0061] The method includes: when the vehicle 1 is approaching an upcoming downhill slope 200 that meets predetermined criteria, controlling s101 the drive unit 2 to reduce the propulsion power provided; disconnecting the drive unit 2 from the first cooling circuit 10 s102; connecting the auxiliary braking device 4 to the first cooling circuit 10 s103; and controlling s104 the auxiliary braking device 4 to brake the vehicle 1 downward along the downhill slope 200.

[0062] When the vehicle 1 is approaching an upcoming downhill slope 200, the step of controlling s101 the drive unit 2 to reduce the provided propulsion power may comprise reducing the provided propulsion power to substantially zero.

[0063] The method may include identifying an upcoming downhill slope 200 that meets a predetermined criterion. The step of controlling s101 the drive unit 2 to reduce the provided propulsion power may include first identifying an upcoming downhill slope 200 that meets the predetermined criterion. The control device 100 may collect data related to the downhill slope 200 from various vehicle sensors, vehicle systems and map data. The control device 100 may also identify an upcoming downhill slope 200 that meets the predetermined criterion based on this collected data. The predetermined criterion may include that the upcoming downhill slope 200 has a certain length and / or a certain gradient. When the downhill slope 200 has a certain length and / or gradient, the vehicle 1 may have to be braked to avoid acceleration of the vehicle 1. The acceleration also depends on the vehicle weight. Therefore, the predetermined criterion related to the downhill slope 200 may depend on the vehicle weight. The control device 100 may include a list of predetermined criteria associated with different vehicle weights stored in a database. The method may therefore include comparing the collected data related to the downhill slope 200 with the list to determine whether the criterion is met. The predetermined criterion may be: the downhill slope 200 is constructed so that the auxiliary braking device 4 is required to brake the vehicle 1 down the downhill slope to avoid uncontrolled behavior or maintain a desired vehicle speed. Therefore, the above method steps may be performed only when the vehicle 1 is approaching a downhill slope 200 requiring the auxiliary braking device 4 to brake the vehicle 1 .

[0064] The step of disconnecting s102 the drive unit 2 from the first cooling circuit 10 may include controlling the first valve arrangement 40. Disconnecting s102 the drive unit 2 from the first cooling circuit 10 may include controlling the first valve arrangement 40 to bypass the first coolant 12 through the first radiator 20.

[0065] The step of connecting the auxiliary brake device 4 to the first cooling circuit 10 s103 may comprise controlling the second valve device 60. Alternatively, connecting the auxiliary brake device 4 to the first cooling circuit 10 s103 may comprise activating the auxiliary brake device 4. Thus, the powertrain 3 may be configured such that the auxiliary brake device 4 is automatically connected to the first cooling circuit 10 when the auxiliary brake device 4 is activated. It will be appreciated that there may be a situation where the auxiliary brake device 4 is already connected to the first cooling circuit 10 when the vehicle 1 is approaching the downhill slope 200. In this case, the method may alternatively comprise ensuring that the auxiliary brake device 4 is connected to the first cooling circuit 10.

[0066] The method may further comprise controlling s105 the powertrain 3 such that propulsion power is provided by means of the energy storage unit 300 of the powertrain 3 before the vehicle 1 has reached the top 210 of the downhill slope 200. In this way, the drive unit 2 is not required to propel the vehicle 1. The step of controlling s105 the powertrain 3 such that propulsion power is provided by means of the energy storage unit 300 may be performed just before, just after or substantially simultaneously with the step of controlling s101 the drive unit 2 to reduce the provided propulsion power.

[0067] The method may further include connecting s106 the auxiliary cooling device 70 of the powertrain 3 to the drive unit 2 when the drive unit 2 has been disconnected s102 from the first cooling circuit 10. Connecting s106 the auxiliary cooling device 70 may include configuring the auxiliary cooling device 70 according to the configuration of the auxiliary cooling device 70 (see Figure 3-5 ) controls the first valve device 40 and / or the third valve device 80 and / or the fourth valve device 90. If the auxiliary cooling device 70 is arranged in association with the bypass circuit 50, connecting the auxiliary cooling device 70 to the drive unit 2 s106 may be automatically performed when the drive unit 2 is disconnected from the first cooling circuit 10 s102.

[0068] Furthermore, the method may include connecting the drive unit 2 to the first cooling circuit 10 s107 when the temperature of the first coolant 12 is below the first maximum temperature of the drive unit 2. Connecting the drive unit 2 to the first cooling circuit 10 s107 may include controlling the first valve device 40 so that the first coolant 12 flowing through the drive unit 2 is allowed to flow through the first radiator 20.

[0069] The method may further comprise disconnecting the auxiliary braking device 4 from the first cooling circuit 10 s108 when the auxiliary braking device 4 is no longer in operation. Disconnecting the auxiliary braking device 4 from the first cooling circuit 10 s108 may comprise controlling the second valve device 60, or it may comprise deactivating the auxiliary braking device 4, whereby it is automatically disconnected from the first cooling circuit 10.

[0070] Figure 7 is a diagram of a form of apparatus 500. Figure 2-5 The control device 100 described may include a device 500 in one form. The device 500 includes a non-volatile memory 520, a data processing unit 510 and a read / write memory 550. The non-volatile memory 520 has a first memory element 530 in which a computer program such as an operating system is stored for controlling the functions of the device 500. The device 500 also includes a bus controller, a serial communication port, an I / O device, an A / D converter, a time and date input and transmission unit, an event counter and an interrupt controller (not depicted). The non-volatile memory 520 also has a second memory element 540.

[0071] A computer program P is provided, comprising routines for controlling a vehicle associated with a downhill slope. The computer program P also comprises: a routine for controlling a drive unit to reduce the propulsion power provided when the vehicle is approaching an upcoming downhill slope that meets a predetermined criterion; a routine for disconnecting the drive unit from a first cooling circuit; a routine for connecting an auxiliary braking device to the first cooling circuit; and a routine for controlling the auxiliary braking device to brake the vehicle down the downhill slope. The computer program P may also comprise a routine for controlling a powertrain to provide propulsion power by means of an energy storage unit of the powertrain before the vehicle has reached the top of the downhill slope. The computer program P may also comprise a routine for connecting the drive unit to the first cooling circuit when the temperature of the first coolant is lower than a first maximum temperature of the drive unit. The computer program P may also comprise a routine for connecting the auxiliary cooling device to the drive unit when the drive unit is disconnected from the first cooling circuit. The program P may be stored in the memory 560 and / or the read / write memory 550 in an executable form or in a compressed form.

[0072] When data processing unit 510 is described as performing a certain function, this means that data processing unit 510 affects a specific portion of a program stored in memory 560 or a specific portion of a program stored in read / write memory 550 .

[0073] The data processing device 510 can communicate with the data port 599 via a data bus 515. The non-volatile memory 520 is intended to communicate with the data processing unit 510 via a data bus 512. The separate memory 560 is intended to communicate with the data processing unit 510 via a data bus 511. The read / write memory 550 is adapted to communicate with the data processing unit 510 via a data bus 514.

[0074] When data is received on the data port 599, the data is temporarily stored in the second memory element 540. When the received input data has been temporarily stored, the data processing unit 510 is ready to implement code execution as described above.

[0075] Part of the method described herein may be implemented by the device 500 with the aid of the data processing unit 510, which runs a program stored in the memory 560 or the read / write memory 550. When the device 500 runs the program, the method described herein is performed.

[0076] The foregoing description of the preferred embodiments of the present invention is provided for illustration and descriptive purposes. It is not intended to be exhaustive or to limit the present invention to the described variants. Many modifications and variations will be apparent to those skilled in the art. These embodiments have been selected and described to best explain the principles of the present invention and its practical application, and thus to make it possible for professionals to understand the present invention for various embodiments and to make various modifications suitable for the intended use.

Claims

1. A method for controlling a vehicle (1) associated with a downhill slope (200), the vehicle (1) having a powertrain (3), the powertrain comprising: a drive unit (2), the drive unit being configured to provide propulsion power; Auxiliary braking device (4); as well as A first cooling circuit (10), the first cooling circuit comprising a first coolant (12); wherein the drive unit (2) and the auxiliary brake device (4) are arranged to be selectively connected or disconnected from the first cooling circuit (10), wherein the drive unit (2) has a first maximum temperature and the auxiliary brake device (4) has a second maximum temperature higher than the first maximum temperature, The method comprises: identifying an upcoming downhill slope (200) that meets predetermined criteria, and controlling (s101) the drive unit (2) to reduce the provided propulsion power when the vehicle (1) is approaching the downhill slope (200); disconnecting the drive unit (2) from the first cooling circuit (10) (s102); connecting the auxiliary brake device (4) to the first cooling circuit (10) (s103); and The auxiliary brake device (4) is controlled (s104) to brake the vehicle (1) moving downward along the downhill slope (200).

2. The method according to claim 1, wherein the predetermined criterion comprises that the upcoming downhill slope (200) has a certain length and / or a certain gradient.

3. The method according to claim 1 or 2, wherein disconnecting (s102) the drive unit (2) from the first cooling circuit (10) comprises controlling a first valve device (40).

4. The method according to claim 1 or 2, wherein connecting (s103) the auxiliary brake device (4) to the first cooling circuit (10) comprises controlling a second valve device (60).

5. The method according to claim 1 or 2, further comprising: Before the vehicle (1) has reached the top (210) of the downhill slope (200), the powertrain (3) is controlled (s105) to provide propulsion power by means of an energy storage unit (300) of the powertrain (3).

6. The method according to claim 1 or 2, further comprising: When the temperature of the first coolant (12) is lower than the first maximum temperature of the drive unit (2), the drive unit (2) is connected to the first cooling circuit (10) (s107).

7. The method according to claim 1 or 2, further comprising: When the drive unit (2) is disconnected from the first cooling circuit (10), the auxiliary cooling device (70) of the power system (3) is connected to the drive unit (2) (s106).

8. A computer program product comprising instructions which, when said program is executed by a computer, cause said computer to carry out the method according to any one of the preceding claims.

9. A computer-readable medium comprising instructions which, when executed by a computer, cause the computer to perform the method according to any one of claims 1 to 7.

10. A powertrain (3) for a vehicle (1), the powertrain (3) comprising: a drive unit (2), the drive unit being configured to provide propulsion power; Auxiliary braking device (4); as well as A first cooling circuit (10), the first cooling circuit comprising a first coolant (12); The drive unit (2) and the auxiliary brake device (4) are arranged to be selectively connected or disconnected from the first cooling circuit (10), wherein the drive unit (2) has a first maximum temperature and the auxiliary brake device (4) has a second maximum temperature higher than the first maximum temperature, and the powertrain (3) further comprises a control device (100) configured to: When the vehicle (1) is approaching an upcoming downhill slope (200) that meets a predetermined criterion, controlling the drive unit (2) to reduce the propulsion power provided; Disconnecting the drive unit (2) from the first cooling circuit (10); connecting the auxiliary brake device (4) to the first cooling circuit (10); and The auxiliary brake device (4) is controlled to brake the vehicle (1) moving downward along the downhill slope (200).

11. The powertrain (3) according to claim 10, further comprising: an energy storage unit (300), The control device (100) is configured to control the energy storage unit (300) to provide propulsion power before the vehicle (1) has reached the top (210) of the upcoming downhill slope (200).

12. A powertrain (3) according to claim 10 or 11, wherein the control device (100) is configured to connect the drive unit (2) to the first cooling circuit (10) when the temperature of the first coolant (12) is lower than a first maximum temperature of the drive unit (2).

13. The powertrain (3) according to claim 10 or 11, further comprising: Auxiliary cooling device (70), The control device (100) is configured to connect the auxiliary cooling device (70) to the drive unit (2) when the drive unit (2) is disconnected from the first cooling circuit (10).

14. A powertrain (3) according to claim 13, wherein the auxiliary cooling arrangement (70) comprises an auxiliary radiator (72) arranged in fluid communication with the drive unit (2).

15. The powertrain (3) according to claim 13, wherein the auxiliary cooling device (70) comprises a heat exchanger (76) arranged in fluid communication with the drive unit (2) and a second cooling circuit (78) having a second cooling medium (77).

16. A power train (3) according to claim 10 or 11, wherein the drive unit (2) comprises a fuel cell.

17. A powertrain (3) according to claim 10 or 11, wherein the auxiliary braking device (4) comprises a retarder.

18. A vehicle (1) comprising a powertrain (3) according to any one of claims 10-17.

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