High-voltage switch, high-voltage on-board power supply network in a motor vehicle and method for operating a high-voltage switch

Abstract

High-voltage switch with a first terminal contact connected to a first fixed contact, a second terminal contact connected to a second fixed contact, a bridge contact arranged between the first fixed contact and the second fixed contact and connecting the first fixed contact to the second fixed contact, the bridge contact being pressed against at least one of the fixed contacts with a contact pressing force and being able to be released from at least one of the fixed contacts with a pull-off force, and a drive acting on the bridge contact in the direction of the pull-off force. A measuring circuit senses a voltage drop between the fixed contacts in case of levitation between at least one fixed contact and the bridge contact and depending on the sensed voltage drop controls the drive in such a way that the drive acts on the bridge contact with a force in the direction of the pull-off force.

Claims

1-16. (canceled)

17. A high voltage switch comprising: a first terminal contact connected to a first fixed contact; a second terminal contact connected to a second fixed contact; a bridge contact arranged between the first fixed contact and the second fixed contact connecting the first fixed contact to the second fixed contact, wherein the bridge contact is pressed against at least one of the fixed contacts with a contact pressure force and can be released from at least one of the fixed contacts with a pull-off force; a drive acting on the bridge contact in the direction of the pull-off force; and a measuring circuit configured to sense a voltage drop between the fixed contacts in the event of levitation between at least one fixed contact and the bridge contact, such that depending on the sensed voltage drop, the drive is controlled in such a way that the drive acts on the bridge contact with a force in the direction of the pull-off force.

18. High voltage switch according to claim 17, wherein the drive is a pyrotechnic drive which can be triggered by the voltage drop between the fixed contacts.

19. High-voltage switch according to claim 17, wherein the bridge contact is in a spring-loaded way pressed against at least one of the fixed contacts with the contact pressure force.

20. High-voltage switch according to claim 17, wherein the measuring circuit is fed by the voltage between the fixed contacts.

21. High voltage switch according to claim 20, wherein the measuring circuit is passive and is formed by the drive in such a way that the drive triggers when a voltage between the fixed contacts is exceeded.

22. High voltage switch according to claim 17, wherein in case of levitation a current flows via the drive, which triggers the drive.

23. High voltage switch according to claim 17, wherein the drive accelerates the bridge contact in the direction of the pull-off force or that the drive cuts the bridge contact in the direction of the pull-off force.

24. High voltage switch according to claim 17, wherein the drive has a bolt which accelerates in the direction of the pull-off force onto the bridge contact in the event that the drive is triggered.

25. High voltage switch according to claim 24, wherein the bridge contact can be separated by the bolt.

26. High-voltage switch according to claim 24, wherein the bridge contact can be lifted from both fixed contacts by the bolt.

27. High voltage switch according to claim 24, wherein the bolt is guided in a housing in which the fixed contacts and the bridge contact are arranged.

28. High-voltage switch according to claim 17, wherein the drive is at least partly arranged in the housing in which the fixed contacts and the bridge contact are arranged.

29. High voltage switch according to claim 17, wherein the drive can be additionally triggered by an external control signal.

30. High voltage switch according to claim 17, wherein the measuring circuit is arranged for sensing a voltage in a voltage band, wherein the voltage band has a lower limit voltage and an upper limit voltage, the upper limit voltage being lower than the voltage of the energy storage which can be connected to the high-voltage switch, and the measuring circuit is configured to activate the drive only for a sensed voltage inside the voltage band.

31. A high-voltage on-board power supply network in a motor vehicle, in which the high-voltage switch according to claim 17 is arranged electrically between an energy storage and a drive train.

32. Method for operating the high-voltage switch of claim 17 comprising: sensing a voltage drop between the fixed contacts in the event of levitation between at least one fixed contact and the bridge contact; and triggering the drive depending on the sensed voltage drop in such a way that the bridge contact is removed from the fixed contacts at least partly by means of the drive with a force in the direction of the pull-off force.

Description

[0043] In the following, the subject matter is explained in more detail by means of a drawing showing examples. In the drawing show:

[0044] FIG. 1a-c a schematic view of a high-voltage switch according to an embodiment;

[0045] FIG. 2 a schematic view of a motor vehicle on-board power supply network.

[0046] FIG. 1 shows a high-voltage switch 2 with a first fixed contact 4a connected to a first terminal contact 6a and a second fixed contact 4b connected to a second terminal contact 6b. The fixed contacts 4a, b are short-circuited with each other via a bridge contact 8.

[0047] The fixed contacts 4a, b and the bridge contact 6 are arranged inside a housing 10. Within the housing 10 the fixed contacts 4a, b are arranged in a fixed position and for example firmly anchored to the housing. In contrast, the bridge contact is movable, especially parallel to the direction 12 in the housing 10.

[0048] Direction 12 indicates a force direction by which the bridge contact 8 is pressed against the fixed contacts 4a, b.

[0049] In the region of the bridge contact 8, especially in the center of the bridge contact 8 between the fixed contacts 4a, b, a firing channel 14 is arranged. The firing channel 14 guides a bolt 16, which can be driven by a pyrotechnic drive 18.

[0050] The pyrotechnical drive 18 is arranged as a measuring circuit and is short-circuited with the fixed contacts 4a, 4b via measuring leads 20a, 20b respectively. Thus a voltage is tapped between the fixed contacts 4a, b by the drive 18. In the drive 18, a resistor not shown here may be provided which, when there is a voltage between the fixed contacts 4a, 4b, heats up due to the flowing current and thus, for example, ignites the pyrotechnic charge in the drive 18.

[0051] In FIG. 1a the switch 2 is shown in the closed position and the bridge contact 8 forms a short circuit between the fixed contacts 4a, 4b. Thus there is no relevant voltage drop across the fixed contacts 4a, b and the drive 18 is not activated.

[0052] By means of a mechanism not shown, the bridge contact 8 can normally be lifted from the fixed contacts 4a, b. During normal operation, a current flows via the bridge contact 8, which can be disconnected easily by lifting the bridge contact 8 from the fixed contacts 4a, b. The bridge contact 8 can also be lifted from only one of the fixed contacts 4a, b and be permanently connected to the other one of the fixed contact 4a, b. This function is well known from conventional relays.

[0053] In case of a fault, especially in case of a short-circuit, the current flowing through the fixed contacts 4a, b and the bridge contact 8 may be a multiple of the normal operating current. Such an increased current can lead to a levitation of the bridge contact 8 from at least one of the fixed contacts 4a, b. This is shown in FIG. 1b.

[0054] In FIG. 1b it can be seen that a large current 22 flows across the bridge contact 8. This large current 22 can be caused by a short circuit, for example. This high current 22 causes a levitation of the bridge contact 8 from the fixed contacts 4a, b. Currents in opposite directions at the end faces of at least one of the fixed contacts 4a, b and the bridge contact 8 lead to an electromagnetic force 24 which causes repulsion between the bridge contact 8 and the fixed contacts 4a, b. Due to this repulsion, a gap is formed between the bridge contact 8 and at least one of the fixed contacts 4a, b. Since very high currents 22 are handled by the switch, an electric arc 24 ignites immediately, which burns across the gap between the bridge contact 8 and at least one of the fixed contacts 4a, 4b.

[0055] This electric arc 24 has a greater resistance than a direct contact between the fixed contacts 4a, b and the bridge contact, so that a voltage drop between the fixed contacts 4a, 4b is greater than a voltage drop in the closed state according to FIG. 1a.

[0056] Due to the increased voltage drop, a current flows from the fixed contact 4a via the measuring leads 20a, 20b and the drive 18. This current causes the drive 18 to be ignited.

[0057] At the moment of ignition of the drive 18, the bolt 16 in the firing channel 14 is accelerated in the direction 28 and hits the bridge contact 8. The bolt 16 can cut the bridge contact 8 or lift it off further from the fixed contacts 4a, 4b. Both the cutting and the lifting will cause the electric arc 24 to extinguish. Switch 2 is then completely open and no current flows through switch 2.

[0058] FIG. 2 shows a block diagram with a switch 2, a drive train 30 and an energy storage 32. Normally, a normal operating current flows through switch 2, which can be easily switched off by lifting the bridge contact 8 from at least one of the fixed contacts 4a, 4b.

[0059] In the case of a short circuit, represented by the dotted line 34 in FIG. 2, the drive train 30 is short-circuited. The internal resistance of the drive train 30 approaches zero and the energy storage 32 is almost short-circuited via switch 2 and the short circuit 34. This leads to a very high short-circuit current 22, which results in the levitation just described. The high-voltage switch 2 then self-sufficiently carries out a disconnection as described above, independently of an external disconnection signal.

[0060] In addition to the described separation, the high-voltage switch or the drive 18 can be driven via control lines 36. The control lines 36 can, for example, be activated in the event of a crash, which in particular occurs without a short circuit, and thus activate the drive 18 in such a case as well. This also leads to a safe disconnection or opening of switch 2 in case of a fault condition that does not cause a short circuit. However, the control line 36 is optional. In the case of the control line, lines 20a, 20b can be electrically decoupled from control line 36, so that a current flow between control line 36 and lines 6a, b can be avoided.