Wiring system for a vehicle and method for designing electrical wires for the wiring system

Abstract

A wiring system (4) for a vehicle (2) is proposed, which has a voltage source (6) and an electrical load (8), whereby the demand on the electrical load (8) depends on external conditions. Furthermore, the wiring system (4) has a load path (10) with an electrical line (12), which connects the voltage source (6) to the electrical load (8); and a first switching element (14), which is arranged in the load path (10) and is used to disconnect the electrical load (8) from the voltage source (6), wherein an operating range (A) of external conditions is defined. B ), within which the function of the electrical load (8) is reasonable, and a control unit (16) is arranged, which is designed to operate if the external conditions exceed the operating range (A B ), the electrical load (8) is prevented from being switched on. In addition, a method for designing an electrical wire (12) of such a wiring system (4) is provided.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of German patent application DE 10 2019 203918.9, filed on March 21, 2019; this prior application is incorporated herein by reference in its entirety. Technical Field

[0003] The present invention relates to a wiring system for a vehicle and a method for designing electrical wires for such a wiring system. Background Art

[0004] In vehicles, in particular motor vehicles, electrical energy is distributed via a wiring system. To this end, the wiring system typically has a plurality of wires that connect a voltage source, such as a vehicle battery, to one or more electrical loads of the vehicle.

[0005] Today, the wires in vehicle wiring systems are designed and sized so that the maximum (specified) current during operation of the wiring system does not cause thermal damage to the wires.

[0006] The thermal load of the wires is also influenced by, for example, the ambient temperature of the respective wires. Motor vehicles and therefore also wiring systems are often designed for use at external temperatures exceeding a temperature range of, for example, -40°C to 85°C or even up to 120°C.

[0007] In order to achieve at least the required operating time and thus not exceed the maximum line temperature (which is the result of the heating of the wire caused by the current flow and the influence of the ambient temperature), today the wires are preferably "oversized" with respect to their wire cross section. This means that the wire cross section is larger than it would / must have to be with respect to the maximum expected thermal load. However, this oversizing is associated with considerable additional costs and weight increase. SUMMARY OF THE INVENTION

[0008] Based on this, the object of the present invention is to provide a wiring system which is designed and produced in a cost-saving and material-saving manner.

[0009] According to the present invention, this object is achieved by an electrical wiring system for a vehicle. The wiring system comprises:

[0010] - at least one voltage source and at least one electrical load, wherein the need to operate the electrical load depends on external conditions and the wiring system is designed for a maximum operating range of external conditions,

[0011] - a load path having at least one electrical line, the load path connecting the voltage source to the electrical load, and

[0012] - a first switching element, which is arranged in the load path and serves to disconnect the electrical load from the voltage source, wherein -

[0013] - defines an operating range for external conditions that is smaller than the maximum operating range,

[0014] A control unit is arranged which is designed to prevent the electrical load from being switched on if external conditions are outside the operating range.

[0015] Advantageous embodiments, further developments and variants are disclosed in the dependent claims.

[0016] The wiring system is designed in particular for use in vehicles, in particular for motor vehicles. It has a voltage source and an electrical load. The operating requirements of the electrical load depend on external conditions. In addition, the wiring system has a load path with electrical wires, which connects the voltage source to the electrical load. External conditions are to be understood as conditions that are external to the wiring system. Such external conditions are therefore neither properties of the load itself nor of the load path.

[0017] Furthermore, the wiring system has a first switching element, which is located in the load path. The first switching element is used to separate the electrical load from the voltage source. The load path defines an electrical connection between the power source and the load and in particular comprises the electrical line and the first switching element.

[0018] Cabling systems are usually, i.e. by default, designed for a (maximum) operating range of external conditions, such as temperature. This means that the individual components of the cabling system, such as lines, electronic components, switches, etc., are by default designed for this maximum operating range.

[0019] Furthermore, an operating range of external conditions is defined within which the functionality of the load makes sense. This means that it only makes sense to use an electrical load within the operating range of external conditions. This operating range is smaller than the maximum operating range.

[0020] Furthermore, a control unit is arranged within the wiring system, which is designed in such a way that a load is prevented from being switched on if the external conditions are not within the operating range. This ensures that, for example, the driver can "turn off" an electrical load only when the external conditions are within the operating range. The operating range is a subrange of the maximum operating range of the external conditions for which the wiring system is designed by default. Thus, by this measure, a part of the wiring system is designed for a different operating range than other parts of the wiring system.

[0021] By preventing loads from being switched on when external conditions are outside the operating range, an optimization of the wiring system is achieved with respect to the loading of the electrical lines. Thus, for example, in cases where switching on an electrical load is not justified under environmental conditions, the electrical load is always switched off. Manual activation is thus effectively prevented in these conditions. In other words, loads are not put into operation "unnecessarily". This enables the wiring system and in particular its design to be designed advantageously with respect to saving material and thus reducing costs.

[0022] Preferably, the external condition is an external temperature. This is in particular the ambient temperature in the load area and / or the ambient temperature outside the vehicle or also the temperature of operating resources in the vehicle. The operating range is a predefined temperature range with an upper temperature limit and then another operating range up to a maximum temperature. The upper temperature limit of the prescribed temperature range has, for example, a value greater than 25° C. and less than or equal to 35° C. or less than or equal to 40° C. or less than or equal to 50° C.

[0023] This embodiment is based on the idea that, when an upper temperature limit is reached or exceeded, preferably the electrical load cannot be switched on. This also limits the maximum wire temperature caused by the current flowing through the wire and makes the overall size of the wire smaller.

[0024] The maximum temperature is, for example, the temperature that can be reached in the vicinity of the load, in particular the maximum ambient temperature outside the vehicle, and for which the wiring system is at least partially designed. The maximum temperature is, for example, 85°C or higher, for example 120°C.

[0025] The maximum temperature is preferably 10° C. or 20° C. higher than the upper temperature limit, in particular 30° C. or 50° C. higher. Another operating range is preferably understood as an operating or operating range of the wiring system, for example with respect to a maximum design temperature (for which the wiring system is designed). Basically, the electrical load can be operated in a range above the upper temperature limit, i.e. in another operating range. However, the need to operate the load in another operating range is usually impractical or unnecessary.

[0026] Preferably, the upper temperature limit can also be adjusted dynamically, for example by the control unit, and if necessary, for example by increasing a specific value, especially in the short term. Depending on the type of load, at least emergency operation of the load may be required. In addition to increasing the temperature limit, i.e. avoiding forced shutdown of the load, a current limiter is preferably provided. This means that in this special operating situation (emergency operation), the current to which the load will be supplied is preferably less than the maximum load current.

[0027] Therefore, in general, in preferred embodiments, the operating range, ie, in particular the specified temperature range, is variable during operation. This means that the operating range can be dynamically adjusted according to the user's priorities, for example to continue to provide safety-related functions and / or to ensure emergency operation when necessary.

[0028] As an alternative to this variability, the scope of work is fixed and cannot be changed during operation of the vehicle, for example, after production and delivery.

[0029] The line cross section of the line is designed only for supplying the load within the operating range at the maximum operating temperature of the line. This design is based on the consideration that the electrical load (must) be supplied with electrical energy via the line preferably only within the operating range, so the maximum line temperature must be designed only for this operating range. The maximum operating temperature is understood here to be a temperature consisting of the external temperature in the immediate vicinity of the line and the current-related heating of the line.

[0030] The electric wire is in particular a single-core wire. Alternatively, the electric wire is a multi-core wire, each core supplying power to a load.

[0031] The design and calculation of the line cross-section is usually carried out in accordance with standards or other regulations, for example according to VDE 0298. In addition to geometrical factors such as the type of installation (single-core, multi-core), the installation position of the line, etc., the decisive factors for the design are the maximum supply current that should flow through the line and the maximum temperature.

[0032] For a given geometric form factor and mounting position, standards and regulations usually indicate different current carrying capacities for different wire cross-sections, usually for a defined wire temperature at, for example, 30°C. For example, according to VDE 0298 T4 06 / 13, Table 11, a single core 0.75 mm2 wire placed in air 2 The current carrying capacity of the core is 15A. For 25mm 2 Core, current carrying capacity is 129 A. The required cross section depends largely on the ambient temperature. For example, in Table 17, the conversion factor according to the above-mentioned VDE standard 0298T4 06 / 13 is taken into account, which is 1.0 at 30°C, 0.71 at 50°C and 0.35 at 65°C.

[0033] The measures taken according to the invention, namely preventing the load from operating at a certain upper temperature limit, allow a considerable saving in material required for the wires, since these wires can be designed with a significantly smaller cross section (compared to the design for the highest operating temperature).

[0034] Thus, the conductor cross section of the electric line is smaller than the cross section required to supply the electric load in another operating range, thus, for example, over the entire operating range of the wiring system (with otherwise identical parameters), in particular with otherwise identical wire structures (single core, multicore; material and structure of conductors and core insulation). Preferably, the wire cross section is at least 2 times, preferably at least 5 times, in particular at least 10 times smaller than the wire cross section required to supply the load in another operating range (up to maximum temperature). By reducing the wire cross section, the material of the wire is reduced, thereby reducing costs and weight.

[0035] This saving is particularly evident in lines designed for high current carrying capacity and intended to meet high current demands. The lines are specifically designed for current carrying capacity of at least 30A, preferably at least 60A, and especially at least 100A.

[0036] In particular, the electrical load is an electrical heating system. In the simplest case, the heating system is an electrical heating element. Alternatively, it has at least one such electrical heating element. Therefore, if the external conditions are outside the operating range, the heating system should preferably not be switched on at all.

[0037] According to a first variant, the heating system or the heating element supports the comfort function of the vehicle occupants to keep them warm. In particular, the heating element is used to heat the passenger compartment, the vehicle seats and / or the steering wheel. Preferably, a heating element is provided for one or more of the above-mentioned components.

[0038] Alternatively or additionally, the heating element is used according to a second variant to heat the operating resources of the vehicle. In this context, the operating resources of the vehicle should be understood in particular as engine and / or transmission oil.

[0039] Alternatively or additionally, the heating element serves to heat vehicle windows, in particular a front window and / or a rear window, and / or to heat vehicle mirrors, in particular side mirrors, and / or other vehicle systems.

[0040] In the case of an electrical load designed as an electrical heating element, a temperature-dependent switch-off has proven to be particularly advantageous and suitable. For example, it can be assumed that the driver does not require a heating function for heating the passenger compartment at ambient temperatures above 30° C. In this case, the upper temperature limit of the operating range would be, for example, 30° C., so that above this temperature, switching on or functioning of the heating element is prevented.

[0041] As a further embodiment, the already mentioned function of the heating element is used here as a heating element for heating operating resources of the vehicle. In particular, in contrast to the above example, the external or ambient temperature of the vehicle is not defined as the external condition, but, for example, the engine temperature of the vehicle is defined as the external condition. For example, if now during operation the measuring device and the control unit detect that the engine is hot, the function of the heating element for heating operating resources is blocked.

[0042] By suppressing the functioning of the electrical load, in particular the heating element, above the specified temperature limit, it can be ensured that the maximum line temperature of the electrical line supplying the heating element (under normal conditions) is preferably not reached. The line must therefore be designed to operate below the specified temperature limit, in particular only within the operating range.

[0043] Preferably, the electrical line has a plurality of line elements, in particular a single core, through which the current is supplied to the load in each case. Thus, the supply of the load is completed by a plurality of line elements. In addition, each of these line elements contains an electronic switching element for switching the electrical load, in particular a semiconductor switch, such as a transistor. Thus, a plurality of electronic switching elements together define a first switching element for switching the load. This design is based on the following considerations: In the case of large electrical consumers, such as heating elements, the limitation of the temperature range initially leads to a smaller required wire cross section. Due to the additional distribution of the load paths over a plurality of line elements, it is only necessary to design these lines to have a lower current-carrying capacity overall, which can then be switched by the electronic switching elements. Each switching element is designed, for example, for a switching current of maximum 10A, maximum 20A or maximum 30A. Thus, compared with previous systems, this measure eliminates the need for costly switching relays, thereby also saving costs for switching elements.

[0044] For example, the measures presented here will reduce the conductor cross section to 25 mm 2 The single-core wires and switch relays (used to provide several kilowatts of heating power to the heating elements) are replaced by multi-core, especially three-core wires, each individual core having a diameter of only 1.5 mm. 2 The conductor cross section is 25 mm, and each is connected to an electronic switching element. Therefore, in this embodiment, the total conductor cross section and the total volume of the required conductor material have been reduced by about 80% (from 25 mm 2 Reduced to a total of 4.5mm 2 ).

[0045] Preferably, the first switching element is configured to normally switch on the load during operation. Normal switching on of the load during operation is understood to mean that the driver can switch the load on or off using the first switching element, for example, during driving. The control unit is further configured to prevent switching of the first switching element if the external conditions exceed the operating range. This ensures that the load is reliably prevented from being switched on, for example, when the external conditions reach or exceed an upper temperature limit.

[0046] According to a preferred embodiment, the second switching element is also located in the wiring system. According to this embodiment, the control unit is configured to disconnect the load via the second switching element if the external conditions are outside the operating range. This embodiment is based on the idea that the electrical load is disconnected by means of the second switching element independently of the switching state of the first switching element. This is the case, for example, if the driver has switched on the electrical load via the first switching element and now, for example due to a change in the ambient temperature, the external conditions are outside the operating range. Here, for example, the switching signal is transmitted via the control unit to the second switching element, thereby disconnecting the load from the voltage source.

[0047] According to a preferred embodiment, at least the first switching element is arranged in a distributor connected to the electric line. At least the first switching element is therefore arranged in a so-called pre-fuse stage. In this context, the pre-fuse stage is understood to be an area within the wiring system, which is preferably located near the voltage source and from which the electric line is led to the individual loads. It has proven to be advantageous to arrange the pre-fuse stage in the close proximity of the voltage source, in particular for space and safety reasons. Usually, a fuse element is additionally arranged in the distributor, for example in each current path. The advantage of the arrangement of at least the first switching element in the distributor is that the maximum possible line length can be designed with the already mentioned smaller line cross section.

[0048] According to an alternative design, the first switching element has an integrated fuse, for example in the form of a safety fuse, to again protect the line from overcurrent. Furthermore, as an alternative and in particular for the arrangement of at least the first switching element in the pre-fuse stage, the first switching element is arranged in the load path before such a fuse.

[0049] Preferably, the wiring system has a measuring device for determining external conditions. In addition, the measuring device is preferably designed to measure the current temperature of the wire. The measured value of the current temperature of the wire is used to determine the external conditions.

[0050] Preferably, the measuring device is designed to determine the current temperature by at least one of the following methods:

[0051] - Directly measure the temperature of the wire, and / or

[0052] - indirectly measure the current operating temperature of the wire via its electrical resistance, and / or

[0053] -Measure the current operating temperature in wiring system components.

[0054] The direct measurement of the wire temperature is carried out, for example, by means of a temperature sensor, which is preferably located directly on the wire to be measured. The indirect measurement of the actual temperature of the wire by means of the wire resistance is based on the consideration that the wire resistance is preferably proportionally related to the wire temperature. Thus, if necessary, the wire temperature can be inferred from the predetermined resistance of the wire by means of the evaluation unit.

[0055] It is understood that when measuring the current temperature in a component of the wiring system, the measuring device receives a temperature signal, for example, from a control unit of the vehicle, which in turn receives a temperature value from a temperature sensor, for example, located in the vehicle. The temperature signal is transmitted to the measuring system, for example, via a BUS communication system. Additionally or alternatively, it is possible to draw conclusions about the temperature of the wire taking into account the date, location and / or season.

[0056] The method for determining the temperature described above makes it possible to easily determine the temperature of the electric wire in several ways and in each case. This means that the temperature determination of the electric wire is not limited to one method and can therefore be applied, for example, to different types of vehicle wiring systems and / or vehicle types for which, for example, different temperature determination methods have proven to be suitable (in particular from a technical point of view).

[0057] According to the invention, the object is also achieved by a method for designing an electrical wire for a wiring system for a vehicle, the wiring system comprising

[0058] - a voltage source and an electrical load, where the demand on the electrical load depends on external conditions,

[0059] - a load path having electrical wires connecting the voltage source to the electrical load, and

[0060] a first switching element, which is arranged in the load path and serves to separate the electrical load from the voltage source, wherein

[0061] -The working range of external conditions is defined, and the wiring system is designed for the total working range of external conditions, which is greater than the working range,

[0062] -Determine the wire cross section according to the operating range so that the wire cross section design of the wire is only suitable for operation within the operating range and not for the total operating range.

[0063] The wiring system is in particular the wiring system described above, which has a voltage source and an electrical load, a load path with an electrical line, and a first switching element. The first step of the method is to define an operating range of external conditions, preferably an external temperature and an operating range in which the load function makes sense. In a second method step, the cross section of the line is then determined according to the defined operating range, so that the electrical line is designed for the cross section of the line to operate within the operating range.

[0064] The advantages and preferred embodiments mentioned with respect to the wiring system shall transfer by analogy to the procedure and vice versa.

[0065] Embodiments of the present invention are explained in detail below with reference to the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] Figure 1 is a wiring system for a motor vehicle according to a first design variant,

[0067] Figure 2 a wiring system for a motor vehicle according to a second design variant, and

[0068] Figure 3 It is a schematic diagram of the working range of the wiring system. DETAILED DESCRIPTION OF THE INVENTION

[0069] In the figures, components having the same function are always indicated by the same reference numerals.

[0070] Figure 1 A vehicle 2 is shown with a wiring system 4 according to a first design variant. The vehicle 2 is in particular a motor vehicle. The wiring system 4 has a voltage source 6 and an electrical load 8. In the exemplary embodiment, the electrical load 8 is an electrical heating element, which is in particular a heating element for heating the passenger compartment or a heating element for heating the fuel of the vehicle 2. The demand for the electrical load 8 depends on external conditions. External conditions are understood here as conditions under which the electrical load is required, which are in particular not characteristics of the load itself.

[0071] The wiring system 4 also has a load path 10 with electrical lines 12 , which connects the voltage source 6 to the electrical load 8 .

[0072] exist Figure 1 In the exemplary embodiment shown, the wiring system 4 has a first switching element 14 located in the load path 10. The first switching element 14 is used to isolate the electrical load 8 from the voltage source 6. The first switching element 14 is particularly designed to normally switch on the load 8 during operation. That is, it is preferably operated by the driver of the vehicle 2.

[0073] In addition, the working range of external conditions A is defined B (See Figure 3 ), within which range the functionality of the electrical load 8 is useful.

[0074] The wiring system 4 also has a control unit 16 which is designed to prevent the electrical loads 8 from being connected if external conditions are outside the operating range, so that the functioning, in particular the functioning of the electrical loads 8 , is not practical.

[0075] exist Figure 1 In the exemplary embodiment shown, the external condition is the external temperature. B It has an upper temperature limit T o The specified temperature range is followed by another operating range B w (See Figure 3 ).

[0076] The wiring system 4 has a measuring device 18 for detecting external conditions. In an exemplary embodiment, the measuring device 18 is electrically connected to the control unit 16. This allows, for example, the measuring device 18 to send a signal to the control unit 16 after detecting an external condition (i.e., an external temperature), which signal contains information about the detected external temperature. Then, based on the received signal with temperature information, a check is performed, for example with the aid of the control unit 16, to determine whether the external condition, i.e., the determined external temperature, is outside a (prescribed) operating range. If the external condition is outside the operating range, the control unit 16 prevents the load 8 from being connected. For this purpose, the control unit 16 is electrically connected to the first switching element 14 in the following manner: the control unit 16, for example, sends a switching signal to the first switching element 14, based on which the electronic load 8 is prevented from being turned on.

[0077] By preventing the electrical load 8 from being switched on by the first switching element 14 or disconnected by the second switching element 20, if the external conditions are not within the operating range, the advantage is that such an effect can be achieved, in particular when using the external temperature as the external condition, a lower temperature load of the electrical line 12 is achieved during operation. This makes it possible to design the conductor cross section of the electrical line 12 for a lower temperature range and therefore for a lower maximum temperature occurring, thereby saving material and costs.

[0078] Furthermore, a second switching element 20 is arranged in the wiring system 4. If the external conditions are outside the operating range, the control unit 16 is also configured to disconnect the electrical load 8 via the second switching element 20. This embodiment is based in particular on the idea that switching on the electrical load 8 should not only be avoided but should also be disconnected if, for example, the external conditions exceed the operating range during operation.

[0079] In the exemplary embodiment, the second switching element 20 is arranged in series with the first switching element 14. In normal operation of the wiring system 4, in particular the electrical load 8, the second switching element 20 is in a closed, i.e. conductive, state. Preferably, the first switching element 14 is used to prevent the electrical load 8 from being switched on. Only when it has been switched on (normally) by the driver of the vehicle 2, for example, and the external conditions are outside the operating range, the second switching element 20 is opened, thereby disconnecting the electrical load 8 from the voltage source 6. The second switching element 20 is also electrically connected to the control unit 16.

[0080] exist Figure 1 In the exemplary embodiment shown, the first switching element 14 and the second switching element 20 are arranged in a power distributor 22. The electrical line 12 is connected to the power distributor 22.

[0081] The arrangement of the first switching element 14 and the second switching element 20 in the distributor 22 makes it possible to form the longest possible length of the electrical line 12 with a reduced line cross section. In this respect, cost and material advantages are advantageously influenced. The design is based on the idea that such a distributor 22 is usually located in the close proximity of the voltage source 6 (e.g. a vehicle battery), so that a large part of the electrical line 12 is "available" for a smaller cross-sectional design.

[0082] In accordance with Figure 1 In the exemplary embodiment of the present invention, the fuse 24 is also located in the distributor 22. The fuse is used to protect the wire 12 from overcurrent. Figure 1 In the exemplary embodiment of the present invention, the fuse 24 is arranged in series with the second switching element 20. Therefore, the fuse 24 (partially viewed) is located between the second switching element 20 and the electrical load 8. The fuse 24 is, for example, a conventional safety fuse. Therefore, in this exemplary embodiment, the first switching element 14 and the second switching element 20 are arranged in a so-called pre-fuse stage.

[0083] Alternatively, only one or two components selected from the first switching element 14 , the second switching element 20 , and the fuse 24 are arranged in the power distributor 22 .

[0084] Figure 2 A wiring system 4 of a vehicle 2 according to a second design variant is shown.

[0085] The wiring system 4 has Figure 1 The wiring system 4 of the first design variant has substantially the same components, i.e. the wiring system 4 has a voltage source 6 and an electrical load 8, whereby the demand on the electrical load 8 also depends on external conditions. In addition, the wiring system 4 has a load path 10 with an electrical line 12, which connects the voltage source 6 to the electrical load 8.

[0086] The wiring system 4 according to the second design variant also has a first switching element 14, which is arranged in the load path and is designed to separate the electrical load 8 from the voltage source 6. Figure 2 In the second exemplary embodiment of the present invention, the first switching element 14 has the fuse 24, that is, the fuse 24 is integrated in the first switching element 14. Therefore, the fuse 24 is also referred to as an integrated fuse 24.

[0087] According to Figure 1 Similar to the first exemplary embodiment of FIG. 4 , the first switching element 14 receives a switching signal from a control unit 16 , which is also located in the wiring system 4 and is electrically connected to the first switching element 14 .

[0088] In addition, according to Figure 2The wiring system 4 has a second switch element 20, which is designed to be switched when the external conditions exceed the working range A. B The electrical load 8 is disconnected from the voltage source 6.

[0089] In accordance with Figure 2 In the exemplary embodiment of , the external condition, in this case the external temperature, is determined by means of a measuring device 18 which is located in the wiring system 4 and is electrically connected to the control unit 16 .

[0090] exist Figure 2 In the exemplary embodiment shown, the second switching element 20 is arranged together with the component formed by the first switching element 14 and the fuse 24 in the power distribution unit 22 .

[0091] Figure 3 The working range A of the wiring system 4 is shown max The working range A max is understood to be the maximum operating range of the wiring system 4, in particular the maximum temperature operating range A of the wiring system 4 max That is, according to Figure 3 Maximum working range A max Indicates the minimum design temperature T min To which maximum design temperature T max , the load path 10, in particular the wire cross section of the load path 10 of the wiring system 4, is designed. In other words, the wires 12 must be designed with respect to their cross section so that they are in A during operation. max Will not be damaged by heat within the working range.

[0092] Wiring system 4 working range A max With working range A B , the working range A B With a lower temperature limit T u and upper temperature limit T o Alternatively, the lower temperature limit T can be omitted u In this case, the lower limit temperature T u is the minimum design temperature T min . Working range A B A generally sensible temperature range is defined for switching on an electrical load 8 which is connected to the voltage source 6 via a corresponding load path 10. This means that in the operating range A B In this case, for example, it is meaningful for the driver of the vehicle 2 to switch on and operate the functionality of the electrical load 8 .

[0093] At the upper temperature limit T o Followed by another work range B w, the operation of the electric load 8 is in principle possible within this other operating range, but is no longer reasonable from the perspective of the driver of the vehicle 2. The driver of the vehicle 2 seems to be unwise and even undesirable to switch on or operate the electric load 8 of the electric heating element designed to heat the interior of the vehicle 2 to above a certain temperature (for example above 40°C). The 40°C in the above embodiment corresponds to the upper temperature limit T o .

[0094] The present invention is not limited to the above exemplary embodiments. In addition, those skilled in the art can derive other variations of the present invention therefrom without departing from the subject matter of the present invention. In particular, all individual features described in conjunction with the exemplary embodiments can also be combined with each other in other ways without departing from the subject matter of the present invention.

Claims

1. A wiring system (4) for a vehicle (2), comprising: at least one voltage source (6) and at least one electrical load (8), wherein the operating requirements of the electrical load (8) depend on external conditions and the wiring system (4) is designed for a maximum operating range of the external conditions, a load path (10) having at least one electrical line (12), which connects the voltage source (6) to the electrical load (8), and a first switching element (14) arranged in the load path (10) for disconnecting the electrical load (8) from the voltage source (6), in- - defines the operating range of the external conditions (A B ), the working range is smaller than the maximum working range (A max ), where the external conditions are understood to be conditions external to the cabling system and not properties of the load itself or of the load path, - a control unit (16) is arranged, which is designed to, if the external conditions exceed the operating range (A B ), then the electrical load (8) is prevented from being turned on; wherein the electrical load (8) is an electrical heating element for heating at least one of the following components of the vehicle (2): a passenger compartment, a vehicle seat, a steering wheel and / or a working fluid; Wherein the external condition is the external temperature, and the operating range (A B ) is a predetermined temperature range with an upper temperature limit (To), followed by a temperature range up to a maximum temperature (T max ) another working range (B w ); If the external temperature is above an upper temperature limit (To), the switching on or functioning of the electric heating element is prevented; According to the working range (A B ) determines the wire cross section of the wire (12), so the design of the wire (12) is only for the working range (A B ) and not for wire cross sections operating within the total operating range.

2. The wiring system (4) according to claim 1, in, If necessary, dynamically adjust the upper temperature limit (T o ).

3. The wiring system (4) according to claim 1, The upper temperature limit (T o ) and the maximum temperature (T max ) is at least 30°C.

4. The wiring system (4) according to claim 1, The highest temperature (T max ) is at least 80°C.

5. The wiring system (4) according to claim 1 in, The electric wire (12) has a wire cross section which is designed only for use in the working range (A B ) supplies power to the load (8).

6. The wiring system (4) according to claim 5, in, With the maximum temperature (T max ) design, the wire cross-section is at least 2 times smaller than the conventional wire cross-section obtained by the design.

7. The wiring system (4) according to claim 1, in, The electrical wire (12) is designed for a current carrying capacity of at least 30A.

8. The wiring system (4) according to claim 1, The electric load (8) is a PTC heating element.

9. The wiring system (4) according to claim 1, in, The electric line (12) has a plurality of power supply cores, and an electronic switching element for switching the electric load (8) is arranged in each power supply core.

10. The wiring system (4) according to claim 1, in, The first switching element (14) is arranged to normally switch the electrical load (8) during operation, and the control unit (16) is arranged to switch the electrical load (8) when external conditions are outside the operating range (A B ) prevents the first switching element (14) from switching.

11. The wiring system (4) according to claim 1, in, A second switch element (20) is also arranged, and a control unit (16) is arranged so that when the external conditions are outside the working range (A B ) when the load (8) is disconnected by the second switch element (20).

12. The wiring system (4) according to claim 1, At least the first switching element (14) is arranged in a power distributor (22), and the electric line (12) is connected to the power distributor (22).

13. The wiring system (4) according to claim 1, The first switching element (14) has an integrated fuse (24) for protecting the electrical line (12) from overcurrent, or is arranged in the load path (10) upstream of the integrated fuse (24).

14. The wiring system (4) according to claim 1, It has a measuring device (18) for detecting external conditions.

15. The wiring system (4) according to claim 14, in, The measuring device (18) is adapted to measure the current temperature of the electric line (12) to determine the external conditions.

16. The wiring system (4) according to claim 15, The measuring device (18) is arranged to determine the current temperature by at least one of the following methods: - directly measuring the temperature of said wire (12), and / or - indirectly measuring the current temperature of the electric wire (12) by means of the resistance of the electric wire (12), and / or - Measurement of the current temperature in components of the wiring system (4).

17. A method for designing an electric wire (12) for a wiring system (4) of a vehicle (2), the wiring system comprising - a voltage source (6) and an electrical load (8), wherein the demand on the electrical load (8) depends on external conditions, a load path (10) having an electrical line (12) which connects the voltage source (6) to the electrical load (8), and a first switching element (14) arranged in the load path (10) for disconnecting the electrical load (8) from the voltage source (6), in - defines the operating range of the external conditions (A B ), the wiring system is designed for the total operating range of the external conditions, which is greater than the operating range (A B ), where the external conditions are understood to be conditions external to the cabling system and not properties of the load itself or of the load path, -According to the working range (A B ) determines the wire cross section of the wire (12), so the design of the wire (12) is only for the working range (A B ) and not for wire cross sections operating within the total operating range; in, The electrical load (8) is an electrical heating element for heating at least one of the following components of the vehicle (2): a passenger compartment, a vehicle seat, a steering wheel and / or a working fluid; Wherein the external condition is the external temperature, and the operating range (A B ) is a predetermined temperature range with an upper temperature limit (To), followed by a temperature range up to a maximum temperature (T max ) another working range (B w ); If the external temperature is above an upper temperature limit (To), switching on or functioning of the electric heating element is prevented.

18. The method according to claim 17, in, The external condition is the external temperature, and the operating range is the temperature upper limit (T o ) is followed by another operating range (B w ), and wherein the wire cross-sectional dimensions are for another working range (B w ) is too small.

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