Patent Description:
Switching assemblies are used in particular for the high-voltage and/or high-current range. Known embodiments have two contacts and a contact bridge, which is movable from a bridging position, in which the contact bridge connects the contacts to one another in an electrically conductive manner, to a separated position, in which the contacts are electrically separated from one another, the switching assembly comprising a detector with at least one detector element by means of which the presence of the contact bridge at the separated position and/or the bridging position is detectable. Often, however, a fault state in which, for example, one of the contacts is welded to the contact bridge is not detected or is incorrectly declared as open or closed. This makes such switching assemblies unreliable. In other known switching assemblies, the switching state is determined by applying a voltage in the circuit and determining the contact state by measuring the voltage drop across the contacts. For this purpose, if there is more than one switching element in the circuit, it will be necessary to close the switching element that is not to be examined. This is laborious.

<CIT>, <CIT>, <CIT> and <CIT> show solutions in which the position of the contact bridge is measured. <CIT> describes a switching arrangement.

It is the object of the present invention to provide a solution that is more reliable and less difficult.

According to the present invention, the solution is accomplished in that the detector comprises at least one two-point controller with a first switching point and a second switching point for the detector element, wherein at least one of the switching points is associated with a position of the contact bridge between the bridging position and the separated position.

In the case of a method according to the present invention for measuring a position of a contact bridge in a switching assembly with two contacts, the solution is accomplished in that, when the contact bridge moves from the bridging position to the separated position, switching from a first output signal to a second output signal takes place at a first switching point and, when the contact bridge moves from the separated position to the bridging position, switching from the second output signal to the first output signal takes place at a second switching point that is different from the first switching point, at least one of the switching points being assigned to a position of the contact bridge between the bridging position and the separated position.

The solution according to the present invention guarantees that, during a movement away from the separated position or away from the bridging position, the detector will not switch until an area, in which a fault may occur, e.g. incomplete separation of a contact bridge that is welded to a contact, has been swept. This allows a reliable detection of a fault state. The switching assembly and the method, respectively, are thus rendered more reliable.

The solution according to the present invention can be improved still further with the following further developments and embodiments, each of which is advantageous in itself and can be combined with other further developments and embodiments in an arbitrary manner.

According to first advantageous embodiment, both switching points may be assigned to positions of the contact bridge between the bridging position and the separated position. An area in which a fault may occur may here be located between the two switching points. One of the switching points may be assigned to a position of the contact bridge that is very close to the bridging position or the separated position. The other switching point may be further away from the separated position or the bridging position.

According to an advantageous embodiment, the other switching point may be assigned to the position of the contact bridge at the bridging position or the separated position. This allows a reliable detection of the contact bridge at the bridging position or the separated position.

According to a further advantageous embodiment, the separated position or the bridging position may lie in an area located between the positions assigned to the first switching point and the second switching point. The reliability can thus be increased still further, since switching will then only take place, when the contact bridge has definitely moved beyond a position associated with the bridging position or the separated position. This may be of advantage e.g. in cases where the contact bridge is movably supported on a further element.

According to an advantageous embodiment, one of the switching points may be assigned to a position located approximately at half the overtravel. In this way, it can be ensured that the closed condition has definitely been reached, when the switching point is reached.

In a compact embodiment, the two-point controller may be part of the detector element. It may be integrated in the detector element or define a component together with the detector element.

In alternative embodiments, the two-point controller may be an element separate from the detector element. It may, for example, be an independent component.

The two-point controller may be implemented in hardware or software. It may be a physical component or it may merely be configured as a software module.

The two-point controller may be programmable. In particular, the first and the second switching point may be programmable or adjustable. The switching points may, for example, be defined as points at which the measurement signal strength falls below or exceeds a certain value.

An output signal of the detector element may be discrete. This allows, for example, easy integration into a digital system. In particular, the output signal may comprise two levels.

According to an advantageous embodiment, the contact bridge may be spring-mounted on a contact bridge carrier. In particular, the contact bridge may be spring-mounted along a switching direction. This allows reliable contacting with a spring force.

For easy and simple measurement, the switching assembly may comprise an indicator element, the position of which is detectable by the detector element. Because the detector element detects the position of the indicator element, the detector can switch depending on the position of the indicator element. The switching operation may here be path-dependent.

According to an advantageous embodiment, the switching assembly may comprise a further detector element. This can make the switching assembly even more reliable.

The further detector element can do without a two-point controller and/or hysteresis.

Advantageously, the switching assembly may comprise two two-point controllers for each detector element. The switching assembly can thus be rendered more reliable.

A first detector element may be assigned to the bridging position and a second detector element may be assigned to the separated position. Advantageously, both the first detector element and the second detector element may have a two-point controller.

According to an embodiment allowing a short measurement path, the detector elements may be tangentially displaced with respect to the switching direction.

The existence of two different switching points can be referred to as hysteresis. A hysteresis region of the two-point controller may be rectangular, so as to allow clearly defined switching operations.

With two detector elements, each with two output signals, a total of four combinations of output signals are possible. One of these combinations can indicate that the switching assembly is definitely open, i.e. that the contact bridge has definitely reached the separated position. One of the combinations can indicate that the switching assembly is definitely closed, i.e. that the contact bridge has definitely arrived at the bridging position. At least one of these combinations can indicate that the switching assembly is in a fault state, i.e. that the contact bridge is neither definitely at the separated position nor definitely at the bridging position. This may, for example, correspond to a state in which one of the contacts is welded. One of the combinations may indicate that the detector has a defect, e.g. if the combination of the signals of the two detector elements does not correspond to any possible position between the separated position and the bridging position.

Alternatively or additionally, a combination of output signals of at least one detector element with at least one further signal, in particular a switching signal, may be evaluated. The switching signal may, for example, be an excitation signal for a switching coil that moves the contact bridge directly or indirectly. If, for example, the excitation signal is set such that the switching coil and thus the contact bridge should be in the separated position, without this separated position being clearly detected by the detector, a defect can be inferred from this.

According to an advantageous embodiment, the at least one detector element may be arranged outside a switching chamber. This will protect the detector element e.g. against electric arcs and/or high voltages that could otherwise damage it. In the case of two detector elements, both detector elements are advantageously arranged outside the switching chamber, in particular with further sensitive parts of the detector.

The indicator element may be arranged within the switching chamber, so as to allow, for example, direct coupling with moving parts.

The indicator element may comprise a permanent magnet. The indicator element may consist of a permanent-magnetic material. For example, the indicator element may comprise rare earths so as to produce a high magnetic field strength that can easily be detected.

According to an advantageous embodiment, the indicator element may be a separate element connected to other, in particular movable, parts of the switching assembly. The indicator element may be connected directly or indirectly in a motion-transmitting manner to parts of the switching assembly that move during the switching operation, e.g. to the contact bridge carrier.

The indicator element may be connected to other parts, e.g. by means of adhesive bonding, welding or soldering. Also a form-fit or a force-fit connection with other parts is possible.

According to a further embodiment, the indicator element may be part of the contact bridge and/or of the contact bridge carrier. A compact structural design will thus be possible. For example, part of the contact bridge or of the contact bridge carrier may be magnetized and thus generate a magnetic field that can be measured with a detector element. In the case of other measurement methods, reflective surfaces, for example, may be used as an indicator element, e.g. in the case of an optical measurement or in a measurement with ultrasound.

In order to allow measurement of a magnetic field, the at least one detector element may comprise a Hall sensor.

For easy mounting, the at least one detector element may be arranged on a printed circuit board. Further elements, such as a two-point controller, a control unit or an evaluation unit, may be provided on the printed circuit board.

In a space-saving embodiment, the at least one detector element may be arranged in a slot in a blow magnet assembly. A blow magnet assembly can be used to extinguish arcs during opening.

The blow magnet assembly may comprise a single broad magnet on one side and two sub-magnets on another side. The at least one detector element may be arranged between the two sub-magnets so as to save space.

Advantageously, the at least one detector element may measure in a contact-free manner.

According to an advantageous embodiment, a magnetic field generated by the indicator element may run at the detector element antiparallel to a magnetic field generated by the blow magnet assembly, when the indicator element is positioned before the detector element.

A magnetic field of the indicator element may dominate when the contact bridge is at the one position, e.g. when the indicator element is positioned before the detector element. A magnetic field of the blow magnet assembly may dominate when the contact bridge is at the other position, e.g. when the indicator element is not positioned before the detector element.

In order to achieve a good signal-to-noise ratio, the difference in the signal strengths used in the measurement may be greater than the signal strength that is necessary for getting from the first switching point to the second switching point of the detector element. The ratio may, in particular, be greater than <NUM>:<NUM>, especially greater than <NUM>:<NUM> or greater than <NUM>:<NUM>.

In particular, the area corresponding to the first switching point and the second switching point may be located centrally in an area between the occurring minimum and maximum signal strengths. This means that interference from outside can have little influence on the measurement. In order to keep an influence of interference low, the area corresponding to the first switching point and the second switching point may have a certain minimum distance to the occurring minimum and maximum signal strengths. The minimum distance may correspond to about at least <NUM>% of the width between the first switching point and the second switching point, preferably to at least <NUM>%, especially to at least <NUM>%. The minimum distance may correspond to about at least <NUM>% of the signal strength of an expected interference signal, preferably to at least <NUM>%, especially to at least <NUM>%.

A switching process may take place around a zero point of the magnetic field. The first switching point may be assigned to a magnetic field in a first direction, the second switching point may be assigned to a magnetic field in a second direction opposite to the first direction. The absolute values of the switching points may here be equal. For example, the first switching point may be at +<NUM> mT and the second switching point may be at -<NUM> mT. Structurally implementing such an embodiment can be particularly easy, since available detector elements, which need not be programmed to special switching values, can simply be used.

In the following, the invention will be explained exemplarily in more detail on the basis of advantageous embodiments with reference to the drawings.

<FIG> show a first embodiment of a switching assembly <NUM>. The switching assembly <NUM> comprises a housing <NUM>. Two terminal elements <NUM> are accessible from the outside for connecting a circuit to be switched. The two terminal elements <NUM> have provided between them a partition <NUM> for electrical insulation. In addition, a connector <NUM> of a detector <NUM> projects from the housing <NUM>. Contacts <NUM> provided inside are each connected to a respective terminal element <NUM> in an electrically conductive manner. In order to connect the two contacts <NUM> to each other, a movable contact bridge <NUM> is provided. The contact bridge <NUM> consists of an electrically conductive material and is adapted to be connected to the contacts <NUM> at two contact points <NUM>, so as to close the circuit.

The contact bridge <NUM> is movably mounted on and partially supported in a contact bridge carrier <NUM>. A projection <NUM> on the contact bridge <NUM> is movable along a switching direction S in a motion link <NUM> of the contact bridge carrier <NUM>. The contact bridge carrier <NUM> has formed thereon a stop <NUM> on one end, which limits the movement of the projection <NUM> and thus of the contact bridge <NUM> along the switching direction S.

The contact bridge <NUM> is preloaded relative to the contact bridge carrier <NUM> by a spring <NUM> acting along the switching direction S. At the separated position T shown in <FIG>, the contact bridge <NUM> is preloaded towards the contact elements <NUM>. The contact bridge carrier <NUM> is fixedly mechanically connected to a drive rod <NUM>, which may be driven e.g. by a coil that is not shown in detail. During a movement along a switching direction S, the contact bridge <NUM> reaches a bridging position B, at which the contact bridge <NUM> conductively connects the contacts <NUM>. After contact has been established, the spring <NUM> is compressed and generates a contact force between the movable contact points <NUM> and the fixed contacts <NUM>, so as to ensure reliable contacting. In this process, the contact bridge <NUM> moves relative to the contact bridge carrier <NUM>.

In order to determine the position of the contact bridge <NUM>, the switching assembly <NUM> comprises a detector <NUM>. The detector <NUM> has two detector elements <NUM>, which detect a magnetic field <NUM> emitted by an indicator element <NUM>. The detector <NUM> includes a first detector element <NUM>, <NUM> and a second detector element <NUM>, <NUM> and is arranged outside a switching chamber <NUM>, so that it will be protected against high voltages and arcs. The indicator element <NUM>, which is configured as a permanent magnet <NUM>, is arranged within the switching chamber <NUM> and is insensitive to high voltages and arcs that may occur when the contacts <NUM> are being separated from the contact bridge <NUM>.

The indicator element <NUM> is fixedly connected to the contact bridge carrier <NUM>. It is attached to the side of the contact bridge carrier <NUM>, e.g. by means of adhesive bonding, welding or a form-fit. The indicator element <NUM> may, for example, comprise rare earths, so as to generate high magnetic field strengths.

The first detector element <NUM>, <NUM> is displaced relative to the second detector element <NUM>, <NUM> along the switching direction S. The first detector element <NUM>, <NUM> may be assigned to the separated position T. The second detector element <NUM>, <NUM> may be assigned to the bridging position B.

In addition, the first detector element <NUM>, <NUM> and the second detector element <NUM>, <NUM> are displaced along a tangential direction U, so as to allow a small displacement along the switching direction S.

The detector elements <NUM>, <NUM>, <NUM> are arranged on a printed circuit board <NUM> on which also other components <NUM> are provided. The detector elements <NUM> are configured as Hall sensors <NUM> which detect magnetic fields.

The detector <NUM> further comprises two-point controllers <NUM> assigned to the detector elements <NUM>. For example, a first two-point controller <NUM>, <NUM> may be integrated in a detector element <NUM>, <NUM>. In a further embodiment, a two-point controller <NUM>, <NUM> may be arranged outside the detector element <NUM>, but may operatively be connected thereto.

The two-point controllers <NUM> are configured to have a first switching point <NUM>, <NUM> and a second switching point <NUM>, <NUM> that is different from the first switching point <NUM>, <NUM>. One of the two switching points <NUM>, <NUM>, <NUM>, <NUM> is assigned to a position of the contact bridge <NUM> between the bridging position B and the separated position T. This position is especially outside a fault area, in which a fault may occur. For example, a contact <NUM> may weld to a contact point <NUM> due to excessively high currents. In an attempt to cause the contact bridge <NUM> to move from the bridging position B to the separated position T, this weld may have the effect that the contact bridge <NUM> moves only slightly away from the bridging position B, e.g. only a few hundred micrometers. Although the contact bridge <NUM> has then left the bridging position B, the circuit has not yet been reliably separated. Due to the fact that one of the switching points <NUM>, <NUM>, <NUM>, <NUM> lies beyond an area in which a faulty contact bridge <NUM> can move, it is guaranteed that the contact bridge <NUM> has actually become detached completely when the switching operation takes place. For example, a switching point <NUM>, <NUM>, <NUM>, <NUM> may be assigned to a position, at which the contact bridge <NUM> is one millimeter, two millimeters, or five millimeters away from the bridging position B.

An explanation of the switching behaviour can be illustrated by <FIG>. There, it can be seen that a two-point controller <NUM> of a detector element <NUM> has a first switching point <NUM> and a second switching point <NUM>. The measured variable relevant to the switching operation, e.g. a measured magnetic field, is plotted on the abscissa. The output signal <NUM> of the detector element <NUM> is shown on the ordinate. The output signal <NUM> may exhibit a first output signal <NUM> with a first signal level or a second output signal <NUM> with a second signal level. In particular, it may be a digital output signal.

The two-point controller <NUM> exhibits a hysteresis. If the measured variable is varied, the output signal <NUM> will be path-dependent. If the signal strength of the measured variable increases, switching from the first output signal <NUM> to the second output signal <NUM> will take place at a second switching point <NUM>. If the signal strength of the measured variable is reduced again, switching back to the first output signal <NUM> will only take place at a first switching point <NUM>. It follows that the first switching point <NUM> and the second switching point <NUM> are spaced apart along the measured variable.

Advantageously, the switching process takes place around a zero point of the magnetic field. The first switching point <NUM> is assigned to a magnetic field in a first direction, the second switching point <NUM> is assigned to a magnetic field in a second direction opposite to the first direction. The absolute values of the magnetic fields belonging to the switching points <NUM>, <NUM> are here equal. For example, the first switching point <NUM> may be at +<NUM> mT and the second switching point <NUM> may be at -<NUM> mT. Structurally implementing such an embodiment can be particularly easy, since available detector elements, which need not be programmed to special switching values, are simply used.

<FIG> shows various embodiments for the positions of the switching points <NUM>, <NUM>, <NUM>, <NUM> and the associated positions <NUM>, <NUM>, <NUM>, <NUM>. In the embodiment shown, at the separated position T, the second switching point <NUM> and the associated position <NUM> are arranged close to the separated position T. The separated position T and the switching point <NUM> and its associated position <NUM> may also coincide, so as to allow a reliable detection of the separated position T.

The first switching point <NUM> and its associated position <NUM> are located between the separation position P and the bridging position B. Furthermore, the first switching point <NUM> and its associated position <NUM> are located between the second switching point <NUM> and its associated position <NUM> and the two switching points <NUM>, <NUM> and their associated positions <NUM>, <NUM> of the further detector element <NUM>, which is assigned to the bridging position B.

A boundary <NUM> of the malfunction area is located between the two switching points <NUM>, <NUM> and between their associated positions <NUM>, <NUM>. This ensures that the detector will switch the detector element <NUM> only to the respective other output signal <NUM>, <NUM>, when the malfunction area <NUM> has been swept.

In the case of the detector element <NUM> assigned to the bridging position B, the switching points <NUM>, <NUM>, <NUM>, <NUM> are arranged in a slightly different manner. Even though the first switching point <NUM> and its associated position <NUM> are again arranged beyond a malfunction area, so that the boundary <NUM> of the malfunction area is located between the two switching points <NUM>, <NUM> and between their associated positions <NUM>, <NUM>, the second switching point <NUM> and its associated position <NUM> are arranged behind the bridging position B. The bridging position B is thus located between the first switching point <NUM> and the second switching point <NUM> and between the respective positions <NUM>, <NUM> associated with these switching points. It follows that switching to the other output signal <NUM> will here only take place after the contact bridge <NUM> has reached the bridging position B. This is possible due to the fact that the contact bridge <NUM> is spring-mounted in the contact bridge carrier <NUM> and the indicator element <NUM> is arranged on the contact bridge carrier <NUM>.

<FIG> shows the movement behaviour of the individual components corresponding to the behaviour just described. A movement of a driving element, e.g. the drive rod <NUM>, is plotted to the right. The respective positions of the moving components are plotted towards the top. A movement curve <NUM> of the contact bridge <NUM> is essentially linear and proportional up to a point at which the bridging position B is reached. From there on, the position of the contact bridge <NUM> does not change anymore, since it is blocked by the contact points <NUM> entering into contact with the contacts <NUM>. In contrast, the movement curve <NUM> of the contact bridge carrier <NUM> shows that, after having reached the bridging position B, the contact bridge carrier <NUM> continues to move linearly and proportionally until it finally reaches an end position as well.

In order to be sure that the bridging position B has definitely been reached, one of the switching points <NUM> and its associated position <NUM> may be located behind the bridging position B. The switching point <NUM> and its associated position <NUM> are thus located in a contact area <NUM> of the contact bridge and in an overtravel area <NUM> of the contact bridge carrier <NUM>. For example, the switching point <NUM> may be located approximately centrally in the overtravel area <NUM>, i.e. approximately at half of the spring travel between contact establishment and full compression of the spring <NUM>.

The bridging position B is thus located between the first switching point <NUM> and the second switching point <NUM> and between their associated positions <NUM>, <NUM>. In addition, the boundary <NUM> of the malfunction area is again located between the two switching points <NUM>, <NUM> and between their associated positions <NUM>, <NUM>. The boundary <NUM> is here located between the bridging position B and the first switching point <NUM> and its associated position <NUM>, respectively.

From the combination of the output signals <NUM> of the two detector elements <NUM>, it can be inferred in which state the switching assembly <NUM> is. For example, if it can be inferred from the output signal <NUM> of the detector element <NUM> assigned to the separated position T that the contact bridge <NUM> has left the separated position T, while from the output signal <NUM> of the detector element <NUM> assigned to the bridging position B it can be inferred that the contact bridge <NUM> has not yet arrived at the bridging position B, a defect may exist.

Also a combination of the output signals <NUM> with a control signal may be used for the purpose of analysis. For example, it can be concluded that a malfunction, such as a weld, exists, if the control signal is such that the contact bridge <NUM> should move away from the bridging position B, but no corresponding output signal <NUM> is present at the detector element <NUM> assigned to the bridging position B.

<FIG> illustrates the magnetic measurement principle that may be used in an exemplary embodiment. The switching assembly <NUM> comprises a blow magnet assembly <NUM>, which comprises a first broad magnet <NUM> on one side and two sub-magnets <NUM> on the other side of the switching chamber <NUM>. The blow magnet assembly <NUM> generates in the switching chamber a magnetic field <NUM> that deflects and thus extinguishes the arcs occurring when the contact bridge <NUM> is being separated from the contacts <NUM>. Magnetic field conducting elements <NUM> close the magnetic circuit.

The indicator element <NUM> generates an additional magnetic field <NUM>. Depending on the position of the indicator element <NUM>, the detector elements <NUM> will see either an inwardly directed total magnetic field or an outwardly directed total magnetic field. The total magnetic field is here established by the superposition of the two magnetic fields <NUM>, <NUM>.

The detector <NUM> is arranged in a slot <NUM> between the two sub-magnets <NUM>.

Claim 1:
A switching assembly (<NUM>), in particular for the high-voltage and/or high-current range, with two contacts (<NUM>) and a contact bridge (<NUM>) movable from a bridging position (B), at which the contact bridge (<NUM>) connects the contacts (<NUM>) to one another in an electrically conductive manner, to a separated position (T), at which the contacts (<NUM>) are electrically separated from one another, wherein the switching assembly (<NUM>) comprises a detector (<NUM>) with at least one detector element (<NUM>, <NUM>, <NUM>) by means of which the presence of the contact bridge (<NUM>) at the separated position (T) and/or the bridging position (B) is detectable, characterized in that the detector (<NUM>) comprises at least one two-point controller (<NUM>, <NUM>, <NUM>) with a first switching point (<NUM>, <NUM>) and a second switching point (<NUM>, <NUM>) for the detector element (<NUM>, <NUM>, <NUM>), wherein at least one of the switching points (<NUM>, <NUM>, <NUM>, <NUM>) is assigned to a position of the contact bridge (<NUM>) between the bridging position (B) and the separated position (T).