Thermal management system for a motor vehicle and method for operating the thermal management system

Abstract

The invention relates to a thermal management system (1) for a motor vehicle, in particular for an electric vehicle or a hybrid electric vehicle, comprising a control unit, a first temperature control section (T1), a second temperature control section (T2), a first pump (P1), a second pump (P2), and a valve arrangement (2), wherein the first temperature control section (T1), the second temperature control section (T2), the first pump (P1), and the second pump (P2) are each connected to the valve arrangement (2), and wherein the valve arrangement (2) can be switched into a first switching position (S1) and a second switching position (S2) by means of the control unit. The invention further relates to an associated method for operating the thermal management system (1).The material costs of the thermal management system (1) and the energy consumption during operation of the thermal management system (1) can be reduced by means of the valve arrangement (2) in the first switching position (S1) the first pump (P1) with the first temperature control section (T1) and the second pump (P2) with the second temperature control section (T2) can be fluidically connected by forming a respective temperature control circuit, wherein the valve arrangement (2) in the second switching position (S2) the first pump (P1) with the second temperature control section (T2) and the second pump (P2) with the first temperature control section (T1) can be fluidly connected by means of the valve arrangement (2) in the second switching position (S2).

Description

The invention relates to a thermal management system for a motor vehicle, in particular for an electric vehicle or a hybrid electric vehicle, having the features of the preamble of claim 1, and to an associated method for operating the thermal management system.Such thermal management systems have a control unit and various temperature control sections, in particular a first temperature control section and a second temperature control section, and associated pumps, in particular a first pump and a second pump. The temperature control sections and the pumps are each connected to a valve arrangement of the thermal management system. The valve arrangement can be switched by means of the control unit into a first switching position and a second switching position. Thus, different ways of flowing through the temperature control sections are made possible. The temperature control sections each have corresponding flow channels through which a heat transfer fluid can be conveyed. By means of the heat transfer fluid, an aggregate connected to these flow channels can be temperature controlled, in particular cooled. The temperature control sections can also be designed as flow circuits.For example, DE 10 2020 206 268 A1 discloses a thermal management system for a battery of a motor vehicle, in particular of an electric vehicle or of a battery-electric vehicle or of a hybrid electric motor vehicle. The thermal management system includes a controller and a first coolant circuit, the first coolant circuit including a battery, a chiller, and a first pump. By means of the first pump, a cooling fluid can be conveyed through the first coolant circuit and thus through the battery and the chiller. The thermal management system further comprises a second coolant circuit, wherein the second coolant circuit has a co-heater, a heating heat exchanger and a second pump. By means of the second pump, the cooling fluid can thus be conveyed through the second coolant circuit and thus through the auxiliary heater and the heating heat exchanger. The first coolant circuit and the second coolant circuit are thermally or thermally fluidically coupled to one another via a coupling device. The control unit is designed to regulate the outputs of the first pump and of the second pump in order to fulfil the requirements for thermal management. The coupling device comprises e.g. a 3-2-way valve and a line connection between the first coolant circuit and the second coolant circuit. The coupling device is then designed as a valve arrangement. The coolant exchange between the second coolant circuit and the first coolant circuit can be regulated via the 3-2 directional valve. A coolant return line serves for returning the coolant from the first coolant circuit into the second coolant circuit. Furthermore, a check valve is provided in the first coolant circuit, which prevents a coolant flow from the auxiliary heater to the chiller.In order to be able to supply or discharge the required heat depending on the need or operating state of the respective temperature control section or coolant circuit, each temperature control section or coolant circuit has a required peak pump output, which can be achieved at maximum load of the respective pump. The installed pump per temperature control section or coolant circuit thus depends on the peak requirement. In the case of a plurality of temperature control sections or coolant circuits, the pumps are therefore each installed with the maximum required pump output. In normal operation, however, the required power is significantly lower, in particular approximately 20-30%, and the operating states do not require the peak power of the associated pump simultaneously in all coolant circuits. This results in high material costs, since the respective pump must always be installed with the correspondingly high peak pump output. However, these particularly efficient pumps are then operated in normal operation in an inefficient power range with correspondingly high energy consumption.The object of the invention is therefore to configure and / or further develop the thermal management system for a motor vehicle and the method for operating the thermal management system in such a way that the problems of the prior art are avoided, at least however, reduced. In particular, the material costs of the thermal management system and the energy consumption during operation of the thermal management system should be lowered.This object on which the invention is based is now achieved firstly by a thermal management system for a motor vehicle having the features of patent claim 1.One aspect of the invention is initially essentially that, by means of the valve arrangement in the first switching position, the first pump can be fluidically connected to the first temperature control section and the second pump can be fluidically connected to the second temperature control section, forming a respective temperature control circuit, wherein, by means of the valve arrangement in the second switching position, the first pump can be fluidically connected to the second temperature control section and the second pump can be fluidically connected to the first temperature control section, forming a respective temperature control circuit.The two pumps are preferably designed differently or differently. The pumps are not fixedly assigned to one of the temperature control sections. By switching the valve arrangement into one of the two switching positions, each temperature control section can then be fluidically coupled to the pump which is more suitable for satisfying the respective temperature control requirement, wherein more suitably relates in particular to the efficiency during operation of the pumps. The thermal management system thus operates more efficiently, so that its energy consumption can be lowered during its operation.Preferably, the valve arrangement comprises a first valve and a second valve. The first temperature control section is connected to a first inlet of the first valve and a first outlet of the second valve. The second temperature control section is connected to a second inlet of the first valve and a second outlet of the second valve. The two temperature control sections are thus each connected on the inlet side to the first valve and each connected on the outlet side to the second valve. With the two valves, the valve arrangement can be implemented particularly simply and cost-effectively. Furthermore, actuation of the two valves is easily possible.Further preferably, the first pump is connected to a first outlet of the first valve and a first inlet of the second valve. The second pump is preferably connected to a second outlet of the first valve and a second inlet of the second valve. The two pumps are thus arranged fluidically between the two valves. The two valves and the two pumps can be arranged in a small installation space, viewed spatially, in such an interconnection.According to an advantageous embodiment of the thermal management system, the two valves are each designed as a 4 / 2-way valve. By means of each 4 / 2-way valve in a first switching position, a flow connection can be realized from the respective first inlet to the respective first outlet and the respective second inlet to the respective second outlet. By means of each 4 / 2-way valve in a second switching position, a flow connection from the respective first inlet to the respective second outlet and the respective second inlet to the respective first outlet can be realized. The flow channels within the 4 / 2-way valves are separated from one another, i.e. there is no mixing of the fluid which is supplied via the respective first inlet with the fluid which is supplied via the respective second inlet in the 4 / 2-way valves. 4 / 2-way valves can be provided economically and can be controlled easily. The 4 / 2-way valves can preferably be switched by means of one actuator each. Preferably, the 4 / 2-way valves are each held in one of the switching positions by a spring when the actuator is not energized, wherein this is preferably the switching position which occurs more often during operation of the thermal management system. The 4 / 2-way valves are preferably of identical construction.Advantageously, the first temperature control section and the second temperature control section each have at least one unit to be temperature controlled, such as a battery or a heat exchanger. A heat transfer fluid can be conveyed through the respective unit by means of the first or the second pump for the purpose of tempering it. Depending on the operating case, the respective unit can be cooled or heated by means of the heat transfer fluid. In this case, a corresponding heat transfer takes place between the heat transfer fluid and the respective unit. The battery can thus always be kept at the temperature required for fault-free operation of the battery, for example. In particular, overheating of the battery can be reliably avoided.According to a further embodiment of the thermal management system, a nominal power of the first pump is greater than a nominal power of the second pump. The rated power means the maximum power of the respective pump that can be achieved in continuous operation. However, the pumps can also be operated with a lower power if this is expedient for achieving the desired temperature control of the units. Pumps with different rated power have an optimum efficiency at different powers, which is in particular in a range close to the rated power. The valve arrangement is then preferably always switched in such a way that overall, together with both pumps, a maximum possible efficiency is achieved. By pumping different rated power, this maximum possible efficiency during operation of the thermal management system is particularly high.According to a further, particularly preferred embodiment of the thermal management system, the rated power of the second pump is less than a respectively required peak pump power of the first and second temperature control sections. This is possible and also expedient since, in normal operation of the thermal management system, the required power is significantly lower, in particular approximately 20-30%, than the peak pump power. Furthermore, the usual operating states in normal operation do not require the peak power of the associated pumps simultaneously in all temperature control sections. Although the rated power of the second pump is less than a respectively required peak pump power of the first and second temperature control sections, the temperature control requirements can nevertheless be met in all normal operating states. The second pump of low rated power can reduce the costs for obtaining the pumps. A temperature control requirement could be, for example, that a specific aggregate should have a temperature in a specific temperature range.The thermal management system further preferably has a third temperature control section and a third pump. The third temperature control section and the third pump are each connected to the valve arrangement. The valve arrangement is designed to connect each pump to different ones of the temperature control sections in terms of flow by realizing respective switching positions alternately, forming a respective temperature control circuit. The designation of the pumps and the temperature control sections as first, second and third pumps or first, second and third temperature control sections is effected merely for the clear assignment. The thermal management system can be extended analogously with further pumps and temperature control sections.The object on which the invention is based is also achieved by a method for operating the thermal management system having the features of patent claim 9.One aspect of the invention is then essentially that the valve arrangement is switched into the first switching position by means of the control unit when the temperature control requirements of the first temperature control section can be realized by means of the first pump and the temperature control requirements of the second temperature control section can be realized by means of the second pump, wherein the valve arrangement is switched into the second switching position by means of the control unit when the temperature control requirements of the first temperature control section can be realized by means of the second pump and the temperature control requirements of the second temperature control section can be realized by means of the first pump.The valve arrangement is furthermore preferably switched by means of the control unit in such a way that the maximum possible efficiency of the thermal management system, in particular of the two pumps, is achieved. The thermal management system is thus operated particularly efficiently and with low energy consumption.According to an advantageous embodiment of the method, the two valves are each switched into the first switching position or in each case into the second switching position by means of the control unit. The first switching position of the valve arrangement then corresponds to the respective first switching position of the two valves and the second switching position of the valve arrangement corresponds to the respective second switching position of the two valves. The method is thus further simplified, so that a complexity of developing the control unit, in particular of creating a corresponding control software, is reduced.There are now a multiplicity of possibilities for advantageously configuring and developing the thermal management system for a motor vehicle and the method for operating the thermal management system. In this regard, reference may first be made to the patent claims subordinate to patent claims 1 and 9. A preferred embodiment of the thermal management system for a motor vehicle and of the method for operating the thermal management system will now be explained or described in more detail below with reference to the drawing and the associated description. The drawing shows: FIG. 1 shows a schematic representation of a hydraulic circuit diagram of an exemplary embodiment of the thermal management system for a motor vehicle having a valve arrangement in a first switching position, and FIG. 2 shows a schematic representation of a hydraulic circuit diagram of the exemplary embodiment of the thermal management system for a motor vehicle from FIG. 1 with the valve arrangement in a second switching position.FIGS. 1 and 2 each show a thermal management system 1 for a motor vehicle, in particular for an electric vehicle or a hybrid electric motor vehicle, having a control unit, a first temperature control section T 1, a second temperature control section T 2, a first pump P 1, a second pump P 2 and a valve arrangement 2. The valve arrangement 2 can be switched into a first switching position S 1 and a second switching position S 2 by means of the control unit not shown here. The pumps P 1, P 2 are designed as hydraulic pumps, for example as vane cell pumps, gear pumps, axial piston pumps or the like. The temperature control sections T 1, T 2 have flow channels which are formed in housing components and / or with the aid of pipes and / or hoses. The control unit is connected to the valve arrangement 2 via control lines. In particular, actuating signals can be transmitted to at least one actuator of the valve arrangement 2.By means of the valve arrangement 2 in the first switching position S 1, the first pump P 1 is fluidically connectable to the first temperature control section T 1 and the second pump P 2 is fluidically connectable to the second temperature control section T 2 forming a respective temperature control circuit. The heat transfer fluid that can be conveyed by the first pump P 1 can then be conveyed from an outlet of the first pump P 1 through the first temperature control section T 1 to an inlet of the first pump P 1. The heat transfer fluid that can be conveyed by the second pump P 2 can then be conveyed from an outlet of the second pump P 2 through the second temperature control section T 2 to an inlet of the second pump P 2. The pumps P 1, P 2 can preferably be driven by means of in each case one electric motor E, which can be supplied with electrical energy via a battery. In contrast, it would also be conceivable to use other types of motors, such as hydraulic motors.By means of the valve arrangement 2 in the second switching position S 2, the first pump P 1 is fluidically connectable to the second temperature control section T 2 and the second pump P 2 is fluidically connectable to the first temperature control section T 1 forming a respective temperature control circuit. The heat transfer fluid that can be conveyed by the first pump P 1 can then be conveyed from an outlet of the first pump P 1 through the second temperature control section T 2 to an inlet of the first pump P 1. The heat transfer fluid that can be conveyed by the second pump P 2 can then be conveyed from an outlet of the second pump P 2 through the first temperature control section T 1 to an inlet of the second pump P 2. The respective temperature control circuits are separated from one another, and a fluid exchange between the temperature control circuits is not provided at first. One of the temperature control circuits which form is symbolized in FIGS. 1 and 2 in each case by a dashed line and the other temperature control circuit which forms is symbolized by a solid line.The first and the second pump P 1, P 2 can be selectively and fluidically connected in alternation to the two temperature control sections T 1, T 2. Thus, the pump P 1, P 2 can always be connected to the temperature control section T 1, T 2, by means of which the temperature control requirements of the respective temperature control section T 1, T 2 can be met particularly well, in particular in the sense of a high energy efficiency.The valve arrangement 2 has a first valve V 1 and a second valve V 2. The first temperature control section T 1 is connected to a first inlet V 1E 1 of the first valve V 1 and a first outlet V 2A 1 of the second valve V 2. The second temperature control section T 2 is connected to a second inlet V 1E 2 of the first valve V 1 and a second outlet V 2A 2 of the second valve V 2. In contrast, it would also be conceivable for the valve arrangement to have only one single valve or more than two valves.The first pump P 1 is connected to a first outlet V 1A 1 of the first valve V 1 and a first inlet V 2E 1 of the second valve V 2. The second pump P 2 is connected to a second outlet V 1A 2 of the first valve V 1 and a second inlet V 2E 2 of the second valve V 2.The two valves V 1, V 2 are each designed as a 4 / 2-way valve. By means of each 4 / 2-way valve, in a first switching position S 1, a flow connection from the respective first inlet V 1E 1, V 2E 1 to the respective first outlet V 1A 1, V 2A 1 and the respective second inlet V 1E 2, V 2E 2 to the respective second outlet V 1A 2, V 2A 2 can be realized. In a second switching position S 2, a flow connection from the respective first inlet V 1E 1, V 2E 1 to the respective second outlet V 1A 2, V 2A 2 and the respective second inlet V 1E 2, V 2E 2 to the respective first outlet V 1A 1, V 2A 1 can be realized by means of each 4 / 2 directional valve. Each 4 / 2-way valve preferably has an actuator for actuating it, wherein the actuators are connected to the control unit. The actuators are designed, for example, as electric linear actuators. The linear actuators are preferably held in one of the switching positions S 1, S 2 with a spring tension and are moved into the respective other switching position S 1, S 2 when the linear actuator is energized or are subsequently held in this other switching position S 1, S 2.The first temperature control section T 1 and the second temperature control section T 2 each have at least one unit A 1, A 2 to be temperature controlled, such as a battery or a heat exchanger. The unit A 1, A 2 to be temperature-controlled could furthermore be an electric machine, in particular a rotor and / or a stator of the electric machine. A heat transfer fluid can be conveyed through the respective unit A 1, A 2 by means of the first or the second pump P 1, P 2 for the purpose of tempering the latter. During the flow of the heat transfer fluid through the respective aggregate A 1, A 2, a heat transfer, in particular of convective type, is made possible between the heat transfer fluid and the respective aggregate A 1, A 2. In addition to its temperature, the level of the heat transfer also depends in particular on the mass flow of the heat transfer fluid and thus on the current pumping capacity of the associated pump P 1, P 2.A rated power of the first pump P 1 is greater than a rated power of the second pump P 2. If the respective pump P 1, P 2 is operated significantly below its rated power, for example at 70-80% of the rated power, only a lower efficiency of the pump P 1, P 2 can be achieved compared to operation at rated power. Since now two pumps P 1, P 2 of different rated power are selectively available for each temperature control section T 1, T 2, in many of the temperature control requirements which arise during operation of the thermal management system 1 and which are associated with the desired heat transfers described above, both pumps P 1, P 2 can be operated close to the respective rated power and thus with high efficiency.The rated power of the second pump P 2 is less than a respectively required peak pump power of the first and second temperature control sections T 1, T 2. Therefore, the number of operating points at which both pumps P 1, P 2 can be operated close to the respective rated power and thus with high efficiency can be further increased. The peak pump output is namely required simultaneously only in one of the temperature control sections T 1, T 2, if at all, but not in both temperature control sections T 1, T 2.It is conceivable for the thermal management system to have a third temperature control section and a third pump. The third temperature control section and the third pump are then each connected to the valve arrangement and the valve arrangement is then designed to connect each pump to different ones of the temperature control sections in terms of flow by realizing respective switching positions, forming a respective temperature control circuit. The valve arrangement is then designed accordingly. For example, in analogy to the two 4 / 2-way valves, two 6 / 6-way valves are then provided, by means of which, for example, the following flow passages are made possible. If the first pump supplies the first temperature control section with heat carrier fluid, the second pump supplies the second or third temperature control section and the third pump supplies the third or second temperature control section. If the second pump supplies the first temperature control section with heat carrier fluid, the first pump supplies the second or third temperature control section and the third pump supplies the third or second temperature control section. If the third pump supplies the first temperature control section with heat carrier fluid, the first pump supplies the second or third temperature control section and the second pump supplies the third or second temperature control section.However, it is also conceivable to design the valve arrangement or its valves differently. Furthermore, more than three pumps and more than three temperature control sections could also be provided.In the method for operating the thermal management system 1 described above, the valve arrangement 2 is switched into the first switching position S 1 by means of the control unit if the temperature control requirements of the first temperature control section T 1 can be realized by means of the first pump P 1 and the temperature control requirements of the second temperature control section T 2 can be realized by means of the second pump P 2. The valve arrangement 2 is switched into the second switching position S 2 by means of the control unit when the temperature control requirements of the first temperature control section T 1 can be realized by means of the second pump P 2 and the temperature control requirements of the second temperature control section T 2 can be realized by means of the first pump P 1.Furthermore, the powers of the pumps P 1, P 2 are preferably controlled and / or regulated by means of the control unit. To determine the temperature control requirements and the powers of the pumps P 1, P 2, temperatures of the aggregates A 1, A 2 and / or of the heat transfer fluid are measured at corresponding points. The values determined then serve in the control unit to determine the temperature control requirements and associated powers of the pumps P 1, P 2 in order to subsequently emit corresponding actuating signals to the pumps P 1, P 2, in particular their electric motors E. If the temperature control requirements of both temperature control sections T 1, T 2 can be met by means of both pumps P 1, P 2, the pumps P 1, P 2 are assigned to the temperature control sections T 1, T 2 in such a way that the energy consumption of the two pumps P 1, P 2 together is minimized.The two valves V 1, V 2 are each switched into the first switching position S 1 or into the second switching position S 2 by means of the control unit. For this purpose, corresponding actuating signals are generated by means of the control unit and transmitted to actuators of the two valves V 1, V 2. Either each valve V 1, V 2 has a separate actuator or both valves V 1, V 2 can be switched using the same actuator. In both cases, the valves V 1, V 2, which are preferably of identical construction, are preferably simultaneously switched from the first switching position S 1 into the second switching position S 2 or vice versa from the second switching position S 1 into the first switching position S 2.List of reference characters1 Thermal management system 2 Valve arrangement T 1 First temperature control section T 2 Second temperature control section P 1 First pump P 2 Second pump V 1 First valve V 2 Second valve S 1 First switching position S 2 Second switching position V 1E 1 First inlet of the first valve V 1 V 1E 2 Second inlet of the first valve V 1 V 1A 1 First outlet of the first valve V 1 V 1A 2 Second outlet of the first valve V 1 V 2E 1 First inlet of the second valve V 2 V 2E 2 Second inlet of the second valve V 2 V 2A 1 First outlet of the second valve V 2 V 2A 2 Second outlet of the second valve V 2 A 1 Aggregate of the first temperature control section to be temperature controlled t1 A2 Unit to be temperature-controlled of the second temperature-control section T2 E electric motorReferences included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedDE 10 2020 206 268 A1

[0003]

Claims

Thermal management system (1) for a motor vehicle, in particular for an electric vehicle or a hybrid electric motor vehicle, having a control unit, a first temperature control section (T1), a second temperature control section (T2), a first pump (P1), a second pump (P2) and a valve arrangement (2), wherein the first temperature control section (T1), the second temperature control section (T2), the first pump (P1) and the second pump (P2) are each connected to the valve arrangement (2), wherein the valve arrangement (2) can be switched by means of the control unit into a first switching position (S1) and a second switching position (S2), characterized in that, that by means of the valve arrangement (2) in the first switching position (S1), the first pump (P1) is fluidically connectable to the first temperature control section (T1) and the second pump (P2) is fluidically connectable to the second temperature control section (T2) forming a respective temperature control circuit, wherein by means of the valve arrangement (2) in the second switching position (S2), the first pump (P1) is fluidically connectable to the second temperature control section (T2) and the second pump (P2) is fluidically connectable to the first temperature control section (T1) forming a respective temperature control circuit.Thermal management system (1) according to Claim 1, characterized in that the valve arrangement (2) has a first valve (V1) and a second valve (V2), wherein the first temperature-control section (T1) is connected to a first inlet (V1E1) of the first valve (V1) and a first outlet (V2A1) of the second valve (V2), wherein the second temperature-control section (T2) is connected to a second inlet (V1E2) of the first valve (V1) and a second outlet (V2A2) of the second valve (V2).Thermal management system (1) according to claim 2, characterised in that the first pump (P1) is connected to a first outlet (V1A1) of the first valve (V1) and a first inlet (V2E1) of the second valve (V2), the second pump (P2) being connected to a second outlet (V1A2) of the first valve (V1) and a second inlet (V2E2) of the second valve (V2).Thermal management system (1) according to Claim 2 or 3, characterized in that the two valves (V1, V2) are each designed as a 4 / 2-way valve, it being possible by means of each 4 / 2-way valve in a first switching position (S1) to realize a flow connection from the respective first inlet (V1E1, V2E1) to the respective first outlet (V1A1, V2A1) and the respective second inlet (V1E2, V2E2) to the respective second outlet (V1A2, V2A2), it being possible by means of each 4 / 2-way valve in a second switching position (S2) to realize a flow connection from the respective first inlet (V1E1, V2E1) to the respective second outlet (V1A2, V2A2) and the respective second inlet (V1E2, V2E2) to the respective first outlet (V1A1, V2A1) can be realized.Thermal management system (1) according to one of the preceding claims, characterized in that the first temperature control section (T1) and the second temperature control section (T2) each have at least one unit (A1, A2) to be temperature controlled, such as a battery or a heat exchanger, wherein a heat transfer fluid can be conveyed through the respective unit (A1, A2) by means of the first or the second pump (P1, P2) for the purpose of controlling the temperature thereof.Thermal management system (1) according to one of the preceding claims, characterized in that a rated power of the first pump (P1) is greater than a rated power of the second pump (P2).Thermal management system (1) according to one of the preceding claims, characterized in that the rated power of the second pump (P2) is less than a respectively required peak pump power of the first and of the second temperature control section (T1, T2).Thermal management system (1) according to one of the preceding claims, characterized in that the thermal management system has a third temperature control section and a third pump, wherein the third temperature control section and the third pump are each connected to the valve arrangement, wherein the valve arrangement is designed to connect each pump to different ones of the temperature control sections in terms of flow by realizing respective switching positions in an alternating manner, forming a respective temperature control circuit.Method for operating a thermal management system (1) for a motor vehicle according to one of the preceding claims, wherein the valve arrangement (2) is switched into the first switching position (S1) by means of the control unit when the temperature control requirements of the first temperature control section (T1) can be realized by means of the first pump (P1) and the temperature control requirements of the second temperature control section (T2) can be realized by means of the second pump (P2), wherein the valve arrangement (2) is switched into the second switching position (S2) by means of the control unit when the temperature control requirements of the first temperature control section (T1) can be realized by means of the second pump (P2) and the temperature control requirements of the second temperature control section (T2) can be realized by means of the first pump (P1).Method according to Claim 9, characterized in that the two valves (V1, V2) are each switched into the first switching position (S1) or in each case into the second switching position (S2) by means of the control unit.

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