Wiring system for a vehicle and method for designing an electrical line of a wiring system

Abstract

A wiring system for a vehicle is specified, which has a voltage source and an electrical load, whereby a need for the electrical load depends on an external condition. Furthermore, the wiring system has a load path with an electrical line, which connects the voltage source to the electrical load, and a first switching element, which is arranged in the load path, for disconnecting the electrical load from the voltage source, wherein a working range of the external condition is defined, within which the function of the electrical load is reasonable, and a control unit is arranged, which is designed in such a way that a switching on of the electrical load is prevented if the external condition lies outside the working range. Furthermore, a method for the design of an electrical line of such a wiring system is given.

Claims

1. A wiring system for a vehicle comprising: at least one voltage source and at least one electrical load, wherein a need for the operation of the electrical load depends on an external condition and the wiring system is designed for a maximum operating range of the external condition; a load path with at least one electrical line, the load path connects the voltage source to the electrical load; and a first switching element, which is arranged in the load path, for separating the electrical load from the voltage source, wherein: a working range of the external condition is defined, which is smaller than the maximum operating range; a control unit is arranged, which is designed in such a way that a switching on of the electrical load is prevented if the external condition lies outside the working range; and a second switching element is arranged and the control unit is arranged to cause disconnection of the load via the second switching element when the external condition is outside the working range.

2. The wiring system according to claim 1, wherein the external condition is an external temperature and the working range is a predetermined temperature range with an upper temperature limit followed by a further working range up to a maximum temperature.

3. The wiring system according to claim 2, in which the upper temperature limit is dynamically adjusted if necessary.

4. The wiring system according to claim 2, wherein the difference between the upper temperature limit and the maximum temperature is at least 30° C., preferably at least 50° C.

5. The wiring system according to claim 1, wherein the maximum temperature is at least 80° C. and in particular at least 100° C. or at least 120° C.

6. The wiring system according to claim 1, wherein the electrical line has a line cross-section which is designed only for supplying the load within the working range.

7. The wiring system according to claim 6, wherein the line cross-section is smaller by at least a factor of 2 and preferably by at least a factor of 10 than a conventional line cross-section which would result from a design for the maximum temperature.

8. The wiring system according to claim 1, wherein the electrical line is designed for a current carrying capacity of at least 30 A, preferably of at least 60 A and more preferably of at least 100 A.

9. The wiring system according to claim 1, wherein the electrical load is an electrical heating element which is used to heat one or more of: a passenger compartment; a vehicle seat; a steering wheel; or an operating fluid of the vehicle.

10. The wiring system according to claim 1, wherein the electrical load is a PTC heating element.

11. The wiring system according to claim 1, wherein the electrical line has several supply cores, and an electronic switching element for switching the electrical load is arranged in each supply core.

12. The wiring system according to claim 1, wherein the first switching element is arranged for normally switching of the load during operation, and the control unit is arranged to block switching of the first switching element when the external condition is outside the working range.

13. The wiring system according to claim 1, wherein at least the first switching element is arranged in a power distributor to which the electrical line is connected.

14. The wiring system according to claim 1, wherein the first switching element has an integrated fuse for protecting the electrical line against overcurrent or is arranged in the load path before such a fuse.

15. The wiring system according to claim 1, further comprising a measuring device for detecting the external condition.

16. The wiring system according to claim 15, wherein the measuring device is adapted to measure a present temperature of the electric line to determine the external condition.

17. The wiring system according to claim 16, wherein the measuring device is arranged to determine the present temperature by at least one of: a direct measurement of the temperature of the electrical line and/or an indirect measurement of the present temperature of the electric line by means of the resistance of the electrical line, a measurement of the present temperature in a component of the wiring system.

18. A method for designing an electrical line of an wiring system for a vehicle, the wiring system comprising: a voltage source and an electrical load, wherein the need for the electrical load depends on an external condition; a load path with an electrical line, which connects the voltage source to the electrical load; and a first switching element, which is arranged in the load path, for separating the electrical load from the voltage source; wherein: a working range of the external condition is defined, the wiring system being designed for a total operating range of the external condition which is larger than the working range; a line cross section of the line is determined as a function of the working range, so that the electrical line is designed with regard to the line cross section only for operation within the working range and not within the total operating range; and a second switching element is arranged and the control unit is arranged to cause disconnection of the load via the second switching element when the external condition is outside the working range.

19. The method according to claim 18, wherein the external condition is an external temperature and the working range is a predetermined temperature range with an upper temperature limit which is followed by a further working range and wherein the line cross-section is undersized for the further working range.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1 is a wiring system of a motor vehicle according to a first design variant;

(2) FIG. 2 the wiring system of the motor vehicle according to a second design variant; and

(3) FIG. 3 an illustration of an operating range of the wiring system.

DETAILED DESCRIPTION OF THE INVENTION

(4) In the figures, parts with the same function are always shown with the same reference signs.

(5) FIG. 1 shows a vehicle 2 with an wiring system 4 according to a first design variant. Vehicle 2 is in particular a motor vehicle. The wiring system 4 has a voltage source 6 and an electrical load 8. The electrical load 8 in the exemplary embodiment is an electrical heating element, which is in particular a heating element for heating a passenger compartment or a heating element for heating a fuel of vehicle 2. A need for the electrical load 8 depends on an external condition. The external condition is understood here as a condition for the need of the electrical load, which is in particular not a characteristic of the load itself.

(6) The wiring system 4 also has a load path 10 with an electrical line 12, which connects the voltage source 6 with the electrical load 8.

(7) In the exemplary embodiment example shown in FIG. 1, the wiring system 4 has a first switching element 14, which is located in 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 especially designed for normal switching on of the load 8 during operation. I.e. it is preferably operated by a driver of vehicle 2.

(8) Furthermore, an working range A.sub.B (see FIG. 3) of the external condition is defined, within which a function of the electrical load 8 is useful.

(9) The wiring system 4 also has a control unit 16, which is designed in such a way that the electrical load 8 is prevented from being connected if the external condition is outside the operating range and thus a function and in particular operation of the function of the electrical load 8 is not practical.

(10) In the exemplary embodiment shown in FIG. 1, the external condition is an external temperature. The working range A.sub.B is a specified temperature range with an upper temperature limit T.sub.o, followed by a further working range B.sub.W (see FIG. 3).

(11) The wiring system 4 has a measuring device 18 to detect the external condition. The measuring device 18 is electrically connected to the control unit 16 in the exemplary embodiment. This makes it possible, for example, for the measuring device 18 to transmit a signal to the control unit 16 after the external condition, i.e. the external temperature, has been detected, which contains information about the detected external temperature. On the basis of the signal received with the temperature information, a check is then carried out by means of control unit 16, for example, to determine whether the external condition, i.e. the determined external temperature is outside the (specified) working range. If the external condition is outside the working range, control unit 16 prevents load 8 from being connected. For this purpose, the control unit 16 is electrically connected to the first switching element 14 in such a way that the control unit 16 transmits e.g. a switching signal to the first switching element 14, on the basis of which the switching on of the electrical load 8 is prevented.

(12) By preventing the switching on of the electrical load 8 by means of the first switching element 14 or the switching off of the electrical load 8 by means of the second switching element 20, if the external condition is outside the working range, the advantage is achieved that, especially when using the external temperature as an external condition, a lower temperature load of the electrical line 12 is achieved during operation. This makes it possible to design a conductor cross-section of electrical line 12 fora lower temperature range and thus fora lower maximum temperature that occurs, thus saving material and costs.

(13) Furthermore, a second switching element 20 is arranged in the wiring system 4. The control unit 16 is also set up to cause the electrical load 8 to be disconnected via the second switching element 20 if the external condition is outside the working range. This embodiment is based in particular on the idea that not only the switching on of the electrical load 8 should be prevented, but also that the electrical load 8 should be switched off if, for example, during operation the external condition is outside the working range.

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

(15) In the exemplary embodiment shown in FIG. 1, 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.

(16) The arrangement of the first switching element 14 and the second switching element 20 in the power distributor 22 makes it possible to form the longest possible length of the electrical line 12 with the reduced line cross section. The cost and material advantage is favorably influenced in this respect. This design is based on the idea that such power distributors 22 are usually located in a close range of the voltage source 6, for example the vehicle battery, and thus a large part of the electrical line 12 is “available” for a smaller cross-sectional design.

(17) In the exemplary embodiment according to FIG. 1, a fuse 24 is also located in the power distributor 22. The fuse serves to protect the electrical line 12 against an overcurrent. In the exemplary embodiment according to FIG. 1, fuse 24 is arranged serially to the second switching element 20. The fuse 24 is therefore (locally viewed) located between the second switching element 20 and the electrical load 8. Fuse 24, for example, is a conventional safety fuse. The first switching element 14 and the second switching element 20 are therefore arranged in the exemplary embodiment in a so-called pre-fuse level.

(18) 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.

(19) FIG. 2 shows a wiring system 4 of a vehicle 2 according to a second design variant.

(20) The wiring system 4 has essentially the same components as the wiring system 4 according to the first design variant according to FIG. 1, i.e. the wiring system 4 has a voltage source 6 and an electrical load 8, whereby the need for the electrical load 8 also depends on an external condition. In addition, the wiring system 4 has a load path 10 with an electrical line 12, which connects the voltage source 6 with the electrical load 8.

(21) 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. However, in the second exemplary embodiment according to FIG. 2, the first switching element 14 has a fuse 24, i.e. fuse 24 is integrated in the first switching element 14. For this reason, fuse 24 is also referred to as an integrated fuse 24.

(22) The first switching element 14 receives—analogous to the first exemplary embodiment according to FIG. 1—switching signals from a control unit 16, which is also located within the wiring system 4 and is electrically connected to the first switching element 14.

(23) Furthermore, the wiring system 4 according to FIG. 2 has a second switching element 20, which is designed to disconnect the electrical load 8 from the voltage source 6 if the external condition is outside the working range A.sub.B.

(24) The external condition, in this case the external temperature, is determined in the exemplary embodiment according to FIG. 2 by means of a measuring device 18, which is located within the wiring system 4 and electrically connected to the control unit 16.

(25) In the exemplary embodiment shown in FIG. 2, the second switching element 20 and the component formed by the first switching element 14 and the fuse 24 are arranged together in a power distributor 22.

(26) FIG. 3 shows a sketched illustration of an operating range A.sub.max of the wiring system 4. The operating range A.sub.max is understood to be a maximum operating range of the wiring system 4, in particular a maximum temperature operating range A.sub.max of the wiring system 4. I.e. the maximum operating range A.sub.max according to FIG. 3 indicates from which minimum design temperature T.sub.min to which maximum design temperature T.sub.max the load paths 10 and in particular the line cross-sections of the load paths 10 of the wiring system 4 are designed. In other words, the electrical lines 12 must be designed with regard to their cross section in such a way that they are not thermally damaged during operation within the Amax operating range.

(27) The operating range A.sub.max of the wiring system 4 has a working range A.sub.B with a lower temperature limit T.sub.u and an upper temperature limit T.sub.o. Alternatively, the lower temperature limit T.sub.u can be omitted. In this case the lower temperature limit T.sub.u is the minimum design temperature T.sub.min. The working range A.sub.B defines a usually reasonable temperature range for the switching on of the electrical load 8 which is connected to the voltage source 6 with the corresponding load path 10. That means within the working range A.sub.B it seems to make sense for a driver of vehicle 2, for example, to switch on and operate the function of electrical load 8.

(28) The upper temperature limit T.sub.o is followed by a further working range B.sub.W, within which operation of the electrical load 8 is possible in principle, but no longer appears to be sensible from the point of view of the driver of vehicle 2. For example, switching on or operating an electrical load 8 designed as an electrical heating element to heat an interior of vehicle 2 above a certain temperature, for example above 40° C., does not appear to be sensible or even wanted by the driver of vehicle 2. The 40° C. of the example described above corresponds to the upper temperature limit T.sub.o.

(29) The invention is not limited to the exemplary embodiments described above. Rather, other variants of the invention can be derived from it by the person skilled in the art without leaving the subject matter of the invention. In particular, all individual features described in connection with the exemplary embodiments can also be combined with each other in other ways without leaving the subject matter of the invention.