Controlled connection of multiple wiring system branches of a vehicle

1. A control unit for the exchange of electrical power between a first, a second, a third, and a fourth wiring system branch of a wiring system of a vehicle, comprising:

a first switching device,

a second switching device,

a third switching device, and

a first, second, third, and fourth terminal configured for connection to the first, second, third and fourth wiring system branches respectively,

wherein the first switching device is connected between the first terminal and the fourth terminal,

the second switching device is connected between the fourth terminal and the third terminal, and

the third switching device is connected between the second terminal and the third terminal.

2. The control unit as claimed in claim 1 , wherein the first switching device comprises a diode connected in parallel with the first switching device, and whose forward direction points from the first terminal to the fourth terminal.

3. The control unit as claimed in claim 1 , wherein the second switching device comprises a diode connected in parallel with the switching device and whose forward direction points from the third terminal to the fourth terminal.

4. The control unit as claimed in claim 1 , wherein the switching devices are electromechanical switches or semiconductor switches.

5. The control unit as claimed in claim 1 , wherein the switching devices are elements chosen from the group consisting of: field effect transistors, bipolar transistors, and IGBTs.

6. The control unit as claimed in claim 1 , further comprising a switching arrangement connected to control inputs of the switching devices for setting switch states of the switching devices, wherein the switching arrangement is configured to set at least one of the following switch states of the switching devices:

(a) a discharge protection state, in which the third switching device is open;

(b) an overvoltage protection state, in which the first, second and third switching devices are closed, or in which the third switching device is open and the first and the second switching devices are closed, or in which the first and the third switching devices are open and the second switching device is closed;

(c) a loading protection state, in which the first and/or the second switching devices are open;

(d) a charging state, in which the first and the third switching devices are closed, or in which the first switching device is open and the second and the third switching devices are closed, or in which the first and the second switching devices are closed and the third switching device is open, or in which the first, the second and the third switching devices are closed;

(e) a recovery state, in which the first switching device is open and the second and the third switching devices are closed;

(f) a default state, in which the first switching device is open and the second and the third switching devices are closed;

(g) a boot state, in which the first switching device is closed, the second switching device is open and the third switching device is closed;

(h) an initial start state, in which the first switching device is open and the second and the third switching devices are closed;

(i) a supplementary start state, in which the second switching device is closed and the first and the third switching devices are closed; and

(j) a fast-start state in which the first, the second and the third switching devices are closed.

7. The control unit as claimed in claim 6 , further comprising a storage state detection unit connected to the switching arrangement and connected to a current sensor and/or to a voltage detection device in order to determine a degree of performance capacity of at least one of the energy stores,

wherein the storage state detection unit or the switching arrangement is configured to generate a combustion engine switch-off recommendation when a degree of performance capacity is above a predetermined limit, wherein the switching arrangement is configured to set the supplementary start state or the fast-start state on receipt of a combustion engine switch-on command, in particular through an input that can be connected to a higher-level engine control unit.

8. The control unit as claimed in claim 7 , further comprising a speed input, wherein the limit at a first speed value presented to the speed input is smaller than it is at a second speed value that is larger than the first speed value.

9. The control unit as claimed in claim 1 , further comprising a current sensor between the first terminal and the first switching device.

10. The control unit as claimed in claim 1 , further comprising a current sensor between the third terminal and the third switching device.

11. The control unit as claimed in claim 1 , further comprising:

a DC/DC converter connected between the first terminal and the second terminal, and

a current sensor connected before or after the DC/DC converter in order to detect the current flowing through the DC/DC converter.

12. A vehicle wiring system comprising:

a control unit for the exchange of electrical power between a first, a second, a third, and a fourth wiring system branch of a wiring system of a vehicle, comprising:

a first switching device,

a second switching device,

a third switching device, and

a first, second, third, and fourth terminal configured for connection to the first, second, third and fourth wiring system branches respectively,

wherein the first switching device is connected between the first terminal and the fourth terminal,

the second switching device is connected between the fourth terminal and the third terminal, and

the third switching device is connected between the second terminal and the third terminal,

the first wiring system branch connected to the first terminal;

the second wiring system branch connected to the second terminal;

the third wiring system branch connected to the third terminal ( 43 );

the fourth wiring system branch connected to the fourth terminal; and

wherein a combustion engine starter and an electrical store coupled to the first wiring system branch;

a further electrical store coupled to the second wiring system branch;

a generator and at least one consuming unit with variable supply voltage coupled to the third wiring system branch; and

a consuming unit with a minimum operating voltage coupled to the fourth wiring system branch.