DE102012106242A1 - Switching device for use in circuit breaker for e.g. opening load circuit in electric car, has switching contact surfaces aligned inclined to closing direction under contact angle ranging between specific values - Google Patents

Abstract

The device (1) has switching contact surfaces (21a, 21b) transferrable from an open position (O) into a closing position in a closing direction (S). The switching contact surfaces are held at a distance from counter contact surfaces (31a, 31b) of a switching contact arrangement (2) in the open position, and electrically conductively lie at the counter contact surfaces in the closing position. The switching contact surfaces are aligned inclined to the closing direction under a contact angle (alpha) ranging between 40 degrees and 50 degrees, preferably 45 degrees. An independent claim is also included for a method for switching a load circuit in an electric vehicle.

Description

The present invention relates to a switching device for opening and closing a load circuit, in particular in an electric vehicle, having at least one switchable in a closing direction from an open position in a closed switching contact surface, which is held in the open position spaced from a mating contact surface of the switching device and electrically conductive in the closed position abuts against the mating contact surface.

Furthermore, the invention relates to a method for switching a load circuit, in particular in an electric vehicle, wherein at least one switching contact surface is transferred in a switching direction from an open position to a closed position and brought into electrical contact with a mating contact surface.

Switching devices and methods of the aforementioned type for switching load circuits are known from the prior art. They are used for example in electric vehicles to disconnect a battery or a rechargeable battery of an electric vehicle when not in use by the consumers or to open the load circuit and thus to disconnect the electrical system from the battery or the accumulator. The switching devices are part of circuit breakers, which are usually Sagittarius.

Especially in electric vehicles can occur due to a relatively low internal resistance of the batteries or accumulators very high short-circuit currents in case of failure of a component. For example, a regular maximum load current can be around 200 A, whereas a short-circuit current can be 5000-9000 A. Currents of this magnitude require in a conventional structure of the switching device mentioned above or in conventional methods for switching load circuits very large locking forces.

The large locking forces are required for high current applications because of the contact rejection that occurs. The contact rejection results from the fact that the current paths to the contact point of a switching contact with a mating contact are coupled to the current paths of the mating contact which are removed from the contact point. A resulting repulsive force is in quadratic order depending on the guided current and can be calculated according to the following formula: F _R = 4.45 x 10 ^-7 x I ² [N / A ² ].

The repulsive force F _R multiplies according to the number of contacts used. For example, for dual contact arrangements, a double repulsive force has to be considered.

In addition to the repulsive force, other current-induced forces can occur. Thus, for example, the terminals of a contact bridge having two symmetrically arranged switching contacts can form a virtually closed conductor loop, which is driven apart by the current flow. From this conductor loop so-called bridge forces F _{B can} result.

Consequently, for example, for a bridge with two symmetrical switch contacts with contact surfaces extending perpendicularly to the closing direction, a total repulsive force F _{R, overall,} results from the following formula: F _R , _total = 2 * F _R + F _B. → F _{R, total} ≈ I ² · 1.4 · 10 ^-6 [N / A ² ].

At a maximum current of 9000 A, the above-mentioned formula for approximating the total repulsive force results, for example, in a necessary minimum closing force of approximately 113.4 N. Such high closing forces can currently be achieved, for example in the case of switching devices with low to medium continuous current carrying capacity for electric vehicles not be provided economically.

The present invention is therefore based on the object, in particular in switching devices for closing load circuits in high-current applications, such as in electric vehicles, to reduce the closing forces.

This object is achieved according to the invention for the switching device mentioned above in that the at least one contact surface is aligned obliquely to the closing direction at a contact angle.

In a method mentioned above, the object is achieved in that the at least one switching contact surface is brought at a contact angle obliquely to the switching direction in contact with the mating contact surface.

As a result of this surprisingly simple solution, the direction of the repulsive force can be decoupled from the closing force acting essentially parallel to the closing direction for bringing together or holding together at least one switching contact and mating contact. For this purpose, for example, a contact carrier carrying at least one contact surface can be bent. The new closing force per contact is thus reduced by the factor of the cosine from the contact angle: F _{s, new} = F _s · cos (α), where F _{S, New} equal to the inventively reduced closing force, F _S equal to the minimum necessary closing force to compensate for the repulsive force and where α represents the contact angle.

As a further advantage, the solution according to the invention reduces the so-called switch-on bounce, which can occur when the at least one switch contact surface strikes the countercontact surface during closing and is reflected by it. Thus, a switching device according to the invention leads to a reduction of switching noise and damage to the switching contacts due to the Einschaltprellens compared to previously known or known from the prior art switching devices.

The solution according to the invention can be optionally supplemented and further improved by the following further, respectively advantageous embodiments:
According to a first advantageous embodiment of a switching contact arrangement according to the invention, the contact angle can be between 40 ° and 50 °. In this range of the contact angle, a compromise between inventive reduction of the switching forces and caused by the contact angle friction forces that can occur during translational and / or rotational opening and closing between the switch contact surface and mating contact surface can be found. The contact angle can be substantially 45 °.

At least one further switching contact surface can be arranged mirror-symmetrically to the at least one switching contact surface. In other words, at least two contact surfaces, at least in a projection transversely to the switching direction, can be arranged mirror-symmetrically opposite one another with respect to a central axis of the switching contact arrangement extending essentially parallel to the switching direction. Thus, due to the oblique arrangement of the at least one switching contact surface occurring transverse forces that extend transversely to the switching direction can be compensated.

The at least one switching contact surface can point away from the central axis of the switching device extending substantially parallel to the switching direction. Thus, the mating contact surface can point in the direction of the central axis. In particular, in the case of a large number of switching contact and mating contact surfaces, forces or bending moments acting on a switching contact carrier in the region of the central axis can thus be compensated.

The switching contact surface may be formed on a switching contact, which protrudes in the switching direction of a contact carrier carrying the switching contact. Thus, the at least one switching contact at least partially function as Lichtbogenfußpunktfalle, by which the base of a switching arc is fixed, so that regardless of the rest of the design of the switching contact arrangement, an emigration of the switching arc is prevented. The switching arc can burn more quietly. Such a configuration of a switching contact arrangement according to the invention can be advantageous even at voltages of about 12 V to be switched, from which a switching arc between the switching contact and the mating contact can occur.

An edge region of the switch contact surface may form an arc base trap for fixing an arc root. Thus, the edge region of a corner, edge and / or a projection of the switching contact may be formed. Thus, for example, the switching arc root is fixed more stable on sharp structures than on curved or blunt projections.

At least in the closed position, a load current path can generate a holding magnetic field which exerts a holding force extending at least parallel to the switching direction, which increases a closing force, which presses the at least one switching contact surface against the mating contact surface, at least in the closed position. Thus, closing forces can be further reduced by the holding force generated by the holding magnetic field pulls the at least one switching contact surface against the mating contact surface and thus the forces to be applied by a drive for the switching contact arrangement to achieve and maintain the necessary closing force can be reduced.

Similarly, the method mentioned at the outset can be further improved in that, at least in the closed position, the at least one switching contact surface is pressed against the mating contact surface at least partially by a holding magnetic field generated by a load current path. The load current path may be part of a load circuit closed by the at least one switching contact.

The above statements on switching devices according to the invention justify, individually and in combination, respective method steps of a method according to the invention for switching a load circuit or for closing and holding together switching contact and mating contact. A person skilled in the art will therefore recognize that in a method according to the invention for switching and holding together switching contact and mating contact, the abovementioned device features of a switching device according to the invention are each in the form of method steps for executing a inventive method can be used or reformulated.

In the following the invention with reference to an embodiment with reference to the accompanying drawings is explained in more detail by way of example. The embodiment represents only one possible embodiment, in which individual features, as described above, can be implemented and omitted independently of each other. In the description of the embodiment, the same features and elements are provided with the same reference numerals for the sake of simplicity.

Show it:

1 a schematic side view of a switching device according to the invention in a closed position; and

2 a schematic side view of a switching device according to the invention in an open position.

1 shows a switching device according to the invention 1 in a closed state C. The switching device 1 includes a switch contact arrangement 2 , a mating contact arrangement 3 , a switch contact carrier 4 and a drive unit 5 ,

The switch contact arrangement 2 includes a first switching contact 20a and a second switching contact 20b , The first switching contact 20a and the other switching contact 20b each form a substantially planar first switching contact surface 21a or another switching contact surface 21b out. The switching contact surfaces 21a . 21b are essentially flush with mating contacts 30a respectively. 30b the mating contact arrangement 3 trained mating contact surfaces 31a respectively. 31b at.

The mating contacts 30a . 30b are from respective mating contact carriers 32a . 32b essentially rigid, ie at least relative to the drive unit 5 kept stationary. The first mating contact carrier 32a and the other mating contact carrier 32b comprise a first holding section 33a or another holding section 33b , for electrical connection of the mating contact arrangement 3 with outside the switching device 1 arranged electrical connection means (not shown) are used. To the first holding section 33a and the other holding section 33b closes a first mating contact attachment section 43a or another Gegenkontaktbefestigungsabschnitt 34b at. The first and the further mating contact attachment section 34a . 34b are from the first or further holding section 33a . 33b at a bending angle β (see 2 ), which is substantially 90 ° less a contact angle α (see 2 ) is.

The switch contact carrier 4 includes a first bridge section 40a and another bridge section 40b comprising a first switch contact attachment portion 41a or another switching contact attachment section 41b wear. The first switch contact fixing portion 41a and the other switch contact attachment portion 41b are opposite the first bridge section 40a or the further bridge section 40b each bent by the bending angle β, so that the first switching contact surface 21a and the other switching contact surface 21b are each aligned at the contact angle α to the closing direction S. A shaft 42 of the switch contact carrier 4 supports the first bridge section 40a and the other bridge section 40b and is movable parallel to the closing direction S in the drive unit 5 added.

The drive unit 5 is designed to a acting in the switching direction S closing force F _S on the shaft 42 exercise the switch contact carrier 4 including the switch contact arrangement 2 on the mating contact arrangement 3 to move and the switch contact surfaces 21a . 21b with the mating contact surfaces 31a . 31b merge. The drive unit 5 may include a hydraulic, pneumatic and / or electromagnetic drive, which is adapted to apply the closing force F _S.

The switching device 1 is essentially mirror-symmetrical to a longitudinally through the shaft 42 passing through the center axis M of the switching device 1 built up. That is, the first switching contact 20a with the first switching contact surface 21a , the first counter contact 30a with the first mating contact surface 31a , the first mating contact carrier 32a , the first holding section 33a , the first mating contact fixing portion 34a , the first bridge section 40a and the first switch contact fixing portion 41a with respect to the central axis M at least in a projection transversely to the switching direction S substantially with respect to the central axis M mirror symmetry to the other switching contact 20b with the further switching contact surface 21b , to the other counter contact 30b with the further mating contact surface 31b , to the other mating contact carrier 32b , another holding section 33b , another mating contact attachment section 34b , further bridge section 40b or further switching contact attachment section 41b built up. The central axis M runs essentially parallel to a height direction Y of the switching contact arrangement facing in the switching direction S. 1 and transverse to a side direction X of the switch contact arrangement 1 , The switching direction S and the closing force F _S extend essentially in the vertical direction Y. The bridge force F _B runs substantially counter to the height direction Y.

In the in 1 shown closed position C flows a first current Ia between the first switching contact 20a and the first mating contact 30a and another current Ib between the other switching contact 20b and the other mating contact 30b , For example, the first current Ia in the switching device 1 into it - and the further current Ib flow out of this. Thus, the first and the further current Ia, Ib each one the switching device 1 corresponding total current I correspond. The first current Ia and the further current Ib cause a first repulsive force F _{R, a} or a further repulsive force F _{R, b} , each perpendicular to the first and further switching contact surface 21a . 21b or first and further mating contact surface 31a . 31b directed away and thus endeavored at least with their respective counter to the switching direction S directed force vector components, the switching contact arrangement 2 against the switching direction S of the mating contact arrangement 3 to push away. Consequently, over the first bridge section 40a a first closing force F _{S, a} and over the other bridge section 40b a further closing force F _{S, b are} applied to compensate for the respective counter to the closing direction S directed portions of the repulsive forces F _{R, a} and F _{R, b} .

Furthermore, a load current path 100 be arranged so that a holding magnetic field exerted by him 101 with magnetic field lines 101 and 101b such with respect to the mating contact arrangement 3 and the switch contact arrangement is arranged such that the magnetic field lines 101 and 101b upper magnetic locking forces F _{101, a} and lower magnetic clamping forces F _{101, b} exercise, which the mating contact arrangement 3 against or the switch contact arrangement 2 in the switching direction S pull each other or press each other and thus can help, the closing force F _S at least in the current-carrying state of the load current path 100 For example, when the switching device 1 in the closed position C current leads to decrease.

2 shows the switching device 1 in an open position O, in which the switch contact arrangement 2 from the mating contact arrangement 3 spaced apart. For the separation of the switching contact arrangement of the mating contact arrangement 3 is the switch contact carrier 4 against the switching direction S has been moved, for example, by the drive unit 5 was driven against the switching direction S.

Between the switch contact arrangement 2 and the mating contact arrangement 3 is a switching arc 6 or in particular a switching arc 60b between the other switching contact 20b and the other mating contact 30b educated. The switching arc 60b has a lower arc root 61b at the other switching contact 20b and an upper arc root 62b at the other counter contact 30b , Between the lower arc base 61b and the upper arc root 62b extends an arc section 63b ,

In the switching direction S of the switching device 2 projecting corners or edges of the switching contacts 20a . 20b form a switch contact side first arc base trap 22a or a switching contact side further arc base trap 22b out. Contrary to the switching direction S of the mating contact arrangement 3 projecting corners or edges of the mating contacts 30a . 30b form a gegenkontaktseitige first Lichtbogenfußpunktfalle 35a or a gegenkontaktseitige further arc base trap 35b out. By in or against the switching direction S prominent position of the switching contact side Lichtbogenfußpunktfallen 22a . 22b or contact-side arc base point traps 35a . 35b wander the lower arc base 61b or the upper arc root 62b at predefined places, namely the respective arc base point traps 22a . 22b respectively. 35a . 35b and are thus prevented uncontrolled between the switch contact arrangement 2 on the one hand and the mating contact arrangement 3 as well as the switch contact carrier 4 to wander on the other side. Thus, the switching arc 60b be prevented from not intended for current or arc transfer sections of the switch contact arrangement 2 , the mating contact arrangement 3 and the switch contact carrier 4 to damage.

Within the inventive concept deviations from the embodiment described above are possible. Thus, a switching device with any number of switching contact arrangements 2 and mating contact arrangements 3 be provided, which is designed to be movable via switch contact carrier and drive units 5 can be provided.

LIST OF REFERENCE NUMBERS

1

switching device

2

Switching contact arrangement

3

Against contact arrangement

4

Switching contact carrier

5

drive unit

6

Switching arc

20a

first switching contact

20b

another switching contact

21a

first switching contact surface

21b

further switching contact surface

22a

switch contact side first arc base trap

22b

Switch contact-side further arc base trap

30a

first counter contact

30b

another counter contact

31a

first mating contact surface

31b

further counter contact surface

32a

first mating contact carrier

32b

another mating contact carrier

33a

first holding section

33b

another holding section

35a

contact-side first arc base trap

35b

against contact side further arc base trap

40a

first bridge section

40b

further bridge section

41a

first switch contact attachment portion

41b

another switching contact attachment section

42

shaft

43a

first mating contact attachment portion

43b

another mating contact attachment section

60b

Switching arc

61b

lower arc base

62b

upper arc base

63b

Arc section

100

Load current path

101

holding magnetic field

101a, 101b

magnetic field lines

C

closed position

F _101a

upper magnetic clamping forces

F _101b

lower magnetic clamping forces

F _B

bridge power

F _{R, a} , F _{R, b}

repulsive force

F _S

closing force

F _{S, a}

first closing force

F _{S, b}

further closing force

I

total current

Ia

first stream

ib

another stream

M

central axis

O

open position

S

switching direction

X

Seitrichtung

Y

height direction

α

contact angle

β

bending angle

Claims (10)

Switching device ( 1 ) for opening and closing a load circuit, in particular in an electric vehicle, with at least one switch contact surface (in a closing direction (S) from an open position (O) into a closed position (C)) ( 21a . 21b ), which in the open position (O) of a mating contact surface ( 31a . 31b ) of the switch contact arrangement ( 2 ) is held spaced and in the closed position (C) electrically conductive on the mating contact surface ( 31a . 31b ) is applied, characterized in that the at least one switch contact surface ( 21a . 21b ) is aligned at a contact angle (α) obliquely to the closing direction (S). Switching device ( 1 ) according to claim 1, characterized in that the contact angle (α) is between 40 ° and 50 °. Switching device ( 1 ) according to claim 1 or 2, characterized in that the contact angle (α) is substantially 45 °. Switching device ( 1 ) according to at least one of claims 1 to 3, characterized in that at least one further switching contact surface ( 21a . 21b ) mirror-symmetrical to at least one switch contact surface ( 21a . 21b ) is arranged. Switching device ( 1 ) according to at least one of claims 1 to 4, characterized in that the at least one switch contact surface ( 21a . 21b ) points away from a substantially parallel to the switching direction (S) extending central axis (M) away. Switching device ( 1 ) according to at least one of claims 1 to 5, characterized in that the at least one switching contact surface ( 21a . 21b ) at a switching contact ( 20a . 20b ) is formed in the switching direction (S) of a the switching contact ( 20a . 20b ) carrying switch contact carrier ( 4 ). Switching device ( 1 ) according to at least one of claims 1 to 6, characterized in that an edge region of the at least one switching contact surface ( 21a . 21b ) an arc base trap ( 22a . 22b ) for fixing an arc root ( 61a . 61b ) trains. Switching device ( 1 ) according to at least one of claims 1 to 7, characterized in that a load current path ( 100 ) at least in the closed position (C) a holding magnetic field ( 101 ), which has an at least parallel to the switching direction (S) extending holding force (F _{101, a} , F _{101, b} ) exerts, at least in the closed position (S) increases a closing force (F _S ), which at least one switching contact surface ( 21a . 21b ) to the mating contact surface ( 31a . 31b ) presses. Method for switching a load circuit, in particular in an electric vehicle, wherein at least one switching contact surface ( 21a . 21b ) in a switching direction (S) from an open position (O) in a closed position (C) and electrically conductively in contact with a mating contact surface ( 31a . 31b ), characterized in that the at least one switch contact surface ( 21a . 21b ) at a contact angle (α) obliquely to Switching direction (S) in contact with the mating contact surface ( 31a . 31b ) is brought. A method according to claim 9, characterized in that at least in the closed position (S), the at least one switching contact surface ( 21a . 21b ) at least partially by one of a load current path ( 100 ) generated holding magnetic field ( 101 ) to the mating contact surface ( 31a . 31b ) is pressed.

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