Switching mechanism for an electrical switching device and an electrical switching device

An switching mechanism is disclosed for an electrical switching device. In at least one embodiment, the switching mechanism is for a low-voltage circuit-breaker. Further, an electrical switching device is disclosed, in particular a low-voltage circuit-breaker, with a switching mechanism.

PRIORITY STATEMENT

The present application hereby claims priority under 35 U.S.C. §119 to German patent application number DE 10 2011 086 filed Nov. 22, 2011, the entire contents of which are hereby incorporated herein by reference.

FIELD

At least one embodiment of the 6invention generally relates to a switching mechanism for an electrical switching device, in particular for a low-voltage circuit-breaker, as well as an electrical switching device, in particular a low-voltage circuit-breaker, with a switching mechanism. At least one embodiment of the invention generally relates to electrical switching devices, in particular to circuit-breakers in the low-voltage range.

BACKGROUND

“Low-voltage” typically refers to voltages of up to approx. 1000 Volt. If the switching isolating distances are designed accordingly, such switching devices can also be designed for switching voltages above 1000 Volt, e.g. up to 6.3 kV. In particular electrical switching devices of this type, such as low-voltage circuit-breakers, are designed to interrupt current paths in the event of an overcurrent or a short-circuit. They can be embodied as single-pole or multi-pole, in particular three-pole.

A switching mechanism for a low-voltage circuit-breaker is known from European patent application EP 0 555 158 A1. It has a movable contact, the manual opening and closing of which, as well as automatic opening because of a fault, such as a short-circuit, is controlled via the switching mechanism. The switching mechanism furthermore has a latch, articulated on a fixed spindle and having a cam surface. The switching mechanism further comprises a toggle formed by a toggle spindle, a lever linked on the one hand to the movable contact and on the other hand to the toggle spindle, as well as a lever articulated on the one hand on the latch and on the other hand on the toggle spindle. The switching mechanism further has a spring attached on the one hand to the toggle spindle and on the other hand to a handle for opening and closing the contacts.

The switching mechanism comprises a lock designed to cooperate with the latch to hold the latter in the locked position. It further comprises a cam-follower roller actuated by the handle and designed to cooperate with the cam surface of the latch to move the latch to the locked position, the handle being able to move to three distinct positions: a closed position in which the spring urges the toggle to an extension position, a manual opening and resetting position where the spring urges the toggle to a broken position wherein the latch is in the locked position, and a tripped position in which the latch is unlocked and the toggle broken. The cam surface comprises a slope change point marking the limit between two successive sections, a first section corresponding approximately to the travel of the handle between the tripped position and the reset position, and a second section corresponding to the reset position, the slope of the first section being such that the resultant of the forces derived from the spring and exerted on the handle urges the handle to the tripped position, and the slope of the second section being such that the handle is urged to the reset position arranged as a stable position holding the latch.

The disadvantage of such a switching mechanism for an electrical switching device is that can result in an undesired tripping of the switching mechanism if the latch is in the locked position and the handle is in the open position. In the case of improper transport of the electrical switching device the result can be that a tripping mechanism of the electrical switching device acts on the lock such that the latch leaves its locked position and thus trips the electrical switching device.

DE 693 06 822 D2 discloses a switching mechanism for a circuit-breaker. In this switching mechanism the handle and the latch can be held in the loaded position in the event of unwanted tripping. The switching mechanism is here characterized in that a cam surface of the latch has a slope change point marking the limit between two successive sections, a first section corresponding approximately to the travel of the handle between the tripped position and the reset position, and a second section corresponding to the reset position, the slope of the first section being such that the resultant of the forces derived from the spring and exerted on the handle urges the handle to the tripped position, and the slope of the second section being such that the handle is urged to the reset position arranged as a stable position holding the latch. Thanks to the profile of the cam surface the reset position of the handle becomes a stable position in which the handle holds the latch regardless of the position of the lock. Although a tripping action of a tripping mechanism which releases the lock cannot be prevented, this has no effect, since the latch is held by the handle. In this way any risk of the tripping and locking system being destroyed, which could occur if these systems are mechanically blocked to prevent an undesired release action, is excluded.

SUMMARY

At least one embodiment of the invention is directed to a switching mechanism for an electrical switching device, in which a latch and a latching element of the switching mechanism can be held securely in a loaded position if the operating lever of the electrical switching device is in an OFF position. The loaded position should in particular be held if, for example because of external influences, the tripping mechanism of the electrical switching device is at least partially actuated.

At least one embodiment of the invention is directed to a switching mechanism for an electrical switching device and/or an electrical switching device. Further features and details of the invention emerge from the subclaims, the description and the attached drawings. Features which are described in connection with embodiments of the inventive switching mechanism of course also apply in connection with embodiments of the inventive electrical switching device and vice versa in each case, so that reference is or can always be reciprocally made to the individual aspects of embodiments of the invention in respect of the disclosure.

According to a first aspect of an embodiment of the invention, a switching mechanism is disclosed for an electrical switching device, in particular for a low-voltage circuit-breaker, having an articulated mechanism for moving a movable contact, an operating lever for manually opening and closing the movable contact via the articulated mechanism, wherein the operating lever has a grip and a terminal link which can be pivoted about a fixed bearing point, a latch mounted so as to rotate about a fixed latch spindle and having a clamping cam, the latch having an end cooperating with a latching element of the switching mechanism for latching and unlatching the latch at the latching element, wherein the latch is in operative contact with the movable contact in order to move the latter via the articulated mechanism, a tensioning roller which can be driven via the operating lever such that when the operating lever is moved the tensioning roller is in operative contact with the latch because it rolls along the clamping cam of the latch, a tensioning element for clamping the operating lever, a tripping mechanism which to move the latching element can be brought into operative contact therewith, as well as a force element which is disposed between the latching element and the tripping mechanism and presses these apart from one another, wherein the force element exerts a force on the latching element in the direction of the end of the latch.

According to a second aspect of an embodiment of the invention, an electrical switching device, in particular a low-voltage circuit-breaker, includes at least one movable contact and at least one fixed contact as well as a switching mechanism for connecting and separating the at least one movable contact and the at least one fixed contact, wherein the switching mechanism is designed according to the first aspect of an embodiment of the invention. Such an electrical switching device, such as a low-voltage circuit-breaker, accordingly has the same advantages as have been fully explained according to the first aspect for the switching mechanism.

Elements with an identical function and effect are provided with the same reference characters inFIGS. 1 to 11in each case.

DETAILED DESCRIPTION OF THE EXAMPLE EMBODIMENTS

The present invention will be further described in detail in conjunction with the accompanying drawings and embodiments. It should be understood that the particular embodiments described herein are only used to illustrate the present invention but not to limit the present invention.

According to a first aspect of an embodiment of the invention, a switching mechanism is disclosed for an electrical switching device, in particular for a low-voltage circuit-breaker, having an articulated mechanism for moving a movable contact, an operating lever for manually opening and closing the movable contact via the articulated mechanism, wherein the operating lever has a grip and a terminal link which can be pivoted about a fixed bearing point, a latch mounted so as to rotate about a fixed latch spindle and having a clamping cam, the latch having an end cooperating with a latching element of the switching mechanism for latching and unlatching the latch at the latching element, wherein the latch is in operative contact with the movable contact in order to move the latter via the articulated mechanism, a tensioning roller which can be driven via the operating lever such that when the operating lever is moved the tensioning roller is in operative contact with the latch because it rolls along the clamping cam of the latch, a tensioning element for clamping the operating lever, a tripping mechanism which to move the latching element can be brought into operative contact therewith, as well as a force element which is disposed between the latching element and the tripping mechanism and presses these apart from one another, wherein the force element exerts a force on the latching element in the direction of the end of the latch.

The latch of an embodiment of the switching mechanism includes a bearing and a sliding block guide, that a rotary element is mounted on the bearing and is guided along the sliding block guide, wherein the rotary movement of the rotary element is restricted by the sliding block guide, that the rotary element is designed such that it can be brought into operative contact firstly with the tensioning roller and secondly with the latching element and that on conclusion of a tensioning operation of the operating lever it holds the latch and the latching element in a loaded position. Furthermore, the latch, the rotary element and the latching element are designed such that during the tensioning operation of the operating lever the latching element is inserted into a recess of the latching element, so that the latching element can move in the direction of the end of the latch and away from the tripping mechanism, so that in the loaded position a gap exists between the latching element and the tripping mechanism.

A switching mechanism designed in this way for an electrical switching device, in particular for a low-voltage circuit-breaker, enables the latch and the latching element to remain in the loaded position in the event of undesired tripping, if the operating lever in the OFF position. In the loaded position of the latch and of the latching element a gap exists between the latching element and the tripping mechanism, so that in the event of an undesired tripping operation the tripping mechanism cannot touch the latching element and the latch and the latching element remain in the loaded position. Thanks to this embodiment of the switching mechanism the loaded position of the latch and of the latching element becomes a stable position, in which undesired tripping, for example as a result of a blow to the electrical switching device, can be prevented. This means that although a tripping action in which the tripping mechanism is moved cannot be prevented, it has no effect, since because of the gap between the latching element and the tripping mechanism the tripping mechanism does not touch the latching element. As a result the risk of damage to the switching mechanism of the electrical switching device can be prevented.

A switching mechanism designed in this way for an electrical switching device enables the latch and the latching element to be held in the loaded position if the operating lever of the switching mechanism is in the OFF position. Positioning the switching mechanism in this way is in particular desirable if electrical switching devices are supplied by the manufacturer to a customer. The customer can, by manually moving the operating lever from the OFF position to an ON position, bring the trip mechanism back into operative contact with the latching element, so that the electrical switching device can, when connected to a supply voltage network, securely protect a consumer in the event of a fault.

By way of the articulated mechanism at least one movable contact of the switching mechanism can be moved. This at least one movable contact can be brought into contact with at least one fixed contact of the electrical switching device, so that a flow of current through the electrical switching device is enabled. To interrupt the flow of current the movable contact can be separated from the fixed contact by way of the articulated mechanism. The operating lever of the switching mechanism is in operative contact with the articulated mechanism. The operating lever has a terminal link which can be pivoted about a fixed bearing point, as well as a grip. The grip can be gripped by a user of the electrical switching device in order to switch the operating lever manually between an OFF and an ON position.

The latch of the switching mechanism is in operative connection with the movable contact to move the movable contact via the articulated mechanism. The latch is rotatably mounted about a fixed latch spindle. In this case the latch spindle can be disposed at one end of the latch or else in the center or close to the center of the latch. The latch has an end cooperating with the latching element of the switching mechanism. The latch can be latched to the latching element via this end. This means that in the latched state, known as the loaded position, the end of the latch abuts the latching element and is held thereby. In the unlatched state the latching element releases the movement of the latch, so that because of the forces acting on it it is rotated about the fixed latch spindle.

The latch further has a clamping cam. The clamping cam itself is formed by the contour of the latch on one side. Abutting this clamping cam of the latch is a tensioning roller which can be driven via the operating lever such that in the event of a movement of the operating lever the tensioning roller rolls along the clamping cam of the latch and thereby swivels it. Advantageously the tensioning roller is disposed rotatably movably on the operating lever, in particular the rocker terminal link of the operating lever. If the latch moves as a result of the tensioning roller rolling on the clamping cam of the latch the tensioning element of the switching mechanism is tensioned or released. This means that depending on the direction in which the tensioning roller rolls along the clamping cam of the latch, the tensioning element is tensioned or released. In the loaded position of the latch and of the latching element the tensioning element is tensioned, so that when the latch is unlatched from the latching element it moves the latch back into its released position. The tensioning element is hence in operative contact with the latch.

The tripping mechanism of the switching mechanism can be brought into operative contact therewith for moving the latching element. In this case the tripping mechanism is moved mechanically. A force element is disposed between the tripping mechanism and the latching element, and presses both elements away from one another. This means that the force element exerts a force on the latching element in the direction of the end of the latch.

Advantageously provision is made in the switching mechanism for a rotary element which is mounted at a bearing of the latch and additionally is guided along a sliding block guide of the latch. By mounting and guiding the rotary element at the bearing or inside the sliding block guide, the rotary movement of the rotary element relative to the latch is restricted or predefined. In this case the rotary element is designed such that it can be brought into operative contact firstly with the tensioning roller and secondly with the latching element. This means that during a rolling operation of the tensioning roller along the clamping cam of the latch the tensioning roller comes into contact with the rotary element and rotates this relative to latch. Thanks to the pivoting movement of the latch and the shape of the rotary element, the rotary element can furthermore come into operative contact with the latching element.

On conclusion of the tensioning operation of the operating lever, the rotary element holds the latch and the latching element in a loaded position. In this case the latch, the rotary element and the latching element are designed and aligned with one another such that during the tensioning operation of the operating lever the rotary element is inserted into a recess of the latching element, so that the latching element can move in the direction of the end of the latch and away from the tripping mechanism, so that in the loaded position a gap arises between the latching element and the tripping mechanism. In other words, the rotary element is first guided along the latching element during the tensioning operation of the latch.

As soon as the rotary element reaches the recess of the latching element, the latching element moves, because of the pretensioning which the force element exerts on the latching element, in the direction of the end of the latch, as a result of which the latching element moves away from the tripping mechanism of the switching mechanism and the gap arises. Insertion of the rotary element means, in the context of an embodiment of the invention, that the rotary element is inserted into the recess of the latching element not actively, through its own motion in the direction of the latching element, but passively, namely by a movement of the latching element in the direction of the rotary element or of the end of the latch. In this case the latching element slides along the rotary element or the contour of the rotary element because of the force acting on it.

During the tensioning operation of the electrical switching device, i.e. the movement of the operating lever from “TRIP” to “RESET”, the tensioning roller presses the rotary element away or rotates the rotary element. In this case the rotary element is designed such that on reaching the loaded position the tensioning roller releases the rotary element, so that this jumps back into its original position under the effect of the force of the latching element.

In the original position of the rotary element the rotary element overlaps the clamping cam of the latch. In the loaded position of the latch the rotary element is held in the original position because of the force acting on the latching element. In this case the rotary element, the latch and the latching element are aligned with one another such that after release of the operating lever or the grip of the operating lever the rotary element holds the tensioning roller and thus the latch in the loaded position. This means that if the grip of the operating lever is released, the tensioning roller remains under pressure on the rotary element or a keep-out area of the rotary element.

In this case the rotary element is in its original position, in which it overlaps the clamping cam of the latch. The rotary element or the keep-out area on the rotary element is designed such that the forces acting in the whole switching mechanism are in equilibrium if the tensioning roller abuts the rotary element, as a result of which the grip or the operating lever necessarily remains in this position. In this loaded position the tripping mechanism can be actuated without a tripping operation being performed on account of a movement of the latch. Because of the gap present in the loaded position between the latching element and the tripping mechanism no pressure can be exerted by the tripping mechanism on the latching element.

In the loaded position the rotary element holds the operating lever in its OFF position. This ensures that the switching mechanism of the electrical switching device, in particular the contacts of the electrical switching device, are not damaged, for example during transport of the electrical switching device.

In this case the switching mechanism of the electrical switching device is designed such that in the event of a movement of the operating lever from the OFF position to the ON position, triggered by a manual actuation of the grip of the operating lever by a user, the tensioning roller is separated from the rotary element, as a result of which the latch can be swiveled under the effect of the tensioning element. This pivoting movement of the latch is however restricted by the latch touching the latching element. This means that after transferring the operating lever from the OFF position to the ON position, known as the switch-on operation of the electrical switching device, the latching element is in operative contact with both the end of the latch and the tripping mechanism.

In the ON position of the operating lever the latching element directly abuts the tripping mechanism, so that the latter, in the event of a movement of the tripping mechanism, can release the latching between the latching element and the latch, so that the electrical switching device can perform a tripping operation, in which because of a movement of the latch the movable contact separates from the fixed contact of the electrical switching device and thereby the flow of current to a consumer is interrupted by the electrical switching device.

According to a preferred development of an embodiment of the invention provision can be made in the case of a switching mechanism for the rotary element to have a keep-out area and for the tensioning roller to abut the keep-out area in the loaded position of the latch and of the latching element. The rotary element can be designed in various ways.

In this case the rotary element is advantageously disposed on the bearing and the sliding block guide of the latch such that it can be guided along the latch and parallel to it. The keep-out area of the rotary element is formed by the part of the rotary element which overlaps the clamping cam of the latch in the original position of the rotary element. The keep-out area of the rotary element is here designed such that the forces, i.e. friction forces, between the tensioning roller and the keep-out area as well as forces that the tensioning element exerts on the latch, are kept in equilibrium if the tensioning roller abuts the keep-out area under pressure.

By the tensioning roller abutting the keep-out area of the rotary element the operating lever remains stationary. In this position, i.e. the loaded position of the latch and the OFF position of the operating lever, the switching mechanism freezes. The keep-out area of the rotary element is in particular designed such that it prevents the tensioning roller rolling along the clamping cam of the latch, counter to the force of the tensioning element acting on the latch.

Advantageously the rotary element is designed and is held on the bearing and the sliding block guide such that on conclusion of the tensioning operation of the operating lever at least the keep-out area of the rotary element overlaps the clamping cam of the latch for the tensioning roller to abut the keep-out area. The keep-out area of the rotary element advantageously has a level or an approximately level shape. This ensures that there is sufficient friction between the tensioning roller and the keep-out area of the rotary element in the loaded position of the latch.

Particularly advantageous is a switching mechanism, in which the rotary element is in operative contact with the latching element such that on conclusion of the tensioning operation of the operating lever, i.e. a movement of the latch because of a manual movement of the operating lever, the latching element presses the rotary element into an original position in which at least the keep-out area of the rotary element overlaps the clamping cam of the latch for abutting the tensioning roller. This means that as soon as, during the tensioning operation of the operating lever and thus of the latch, the tensioning roller which initially swiveled the rotary element out of its original position loses the contact with the rotary element, the rotary element jumps back to its original position under the effect of the force of the latching element, so that in the case of a reverse movement of the tensioning roller along the clamping cam of the latch the tensioning roller comes to a stop on the rotary element or on the keep-out area because of the equilibrium of the prevailing forces. This means that after release of the grip of the operating lever the tensioning roller moves back again on the clamping cam of the latch, under the effect of the tensioning element, and remains on the keep-out area of the rotary element under pressure.

According to another preferred development of an embodiment of the invention, provision can be made in the case of a switching mechanism for a force of the tensioning element to be applied to the operating lever such that on conclusion of the tensioning operation of the operating lever and a subsequent release of the operating lever the tensioning roller can, under the effect of the tensioning element, roll along the clamping cam of the latch until it abuts the keep-out area of the rotary element in equilibrium of the operative forces in the switching mechanism. This means that the friction forces arising at the keep-out area between the tensioning roller and the rotary element counter the force of the tensioning element exerted on the latch such that when the tensioning roller contacts the keep-out area of the rotary element the rotary element holds the grip or the operating lever in the OFF position and the latch and the latching element are tensioned.

The latch has both a bearing and a sliding block guide for the rotary element, to guide this relative to the latch. In this case the bearing can be disposed on or in the end of the latch facing the latching element. Preferably the bearing is formed by a bending or a relief cut at the end of the latch. The sliding block guide in which the rotary element is additionally mounted permits only a particular movement of the rotary element relative to the latch. In this case the sliding block guide, the bearing and the rotary element are designed such that with the rotary element in its original position at least its keep-out area overlaps the clamping cam of the latch. In this original position of the rotary element the rotary element or a bolt of the rotary element strikes against an end of the sliding block guide. The sliding block guide can be designed in a variety of ways. Preferably the sliding block guide is designed as a bent slot in the end of the latch facing the latching element.

The rotary element advantageously has a concentric contour about its axis of rotation, which functions as a roller during the tripping operation. At the end of the tensioning operation the latching element or an edge on the recess of the latching element slides along the concentric contour of the rotary element. Thanks to this latching or type of latching, good start-up security is ensured with low tripping forces.

The rotary element itself can be designed in a variety of ways. Thus the rotary element can be movably guided on one side of the latch, parallel or approximately parallel to the latch. Advantageously the rotary element has a level base body which is guidably held by a bolt on the bearing of the latch and by another bolt in the sliding block guide of the latch. The two bolts advantageously project out of the base body of the rotary element and perpendicular thereto. Alternatively the rotary element can have a knife-edge bearing.

According to an alternative preferred development of an embodiment of the invention provision can be made in the case of a switching mechanism for a rotary element to be provided with two base bodies, wherein a first base body is movably disposed on a first side of the latch and the second base body on the other side of the latch. The two base bodies of the rotary element are guided by two bolts which are mounted in the sliding block guide and on the bearing of the latch. It is also conceivable for a switching mechanism to be provided with two completely separate rotary elements. Advantageously the latch is disposed between the two rotary elements.

According to another preferred development of an embodiment of the invention provision can be made in the case of an alternative switching mechanism for two latches to be provided, between which a rotary element is movably disposed.

The tensioning element for tensioning the operating lever of the switching mechanism can be designed in a variety of ways. Advantageously the tensioning element is designed as a spring element, in particular as a tension spring or compression spring. Other types of spring element, for example a leg spring, are also conceivable as a tensioning element. Provision is further advantageously made in the case of a switching mechanism for the force element disposed between the latching element and the tripping mechanism of the switching mechanism to be designed as a spring element. Advantageously this spring element is designed as a leg spring. However, it is also conceivable for the force element to be designed as a spiral spring, in particular as a tension spring or compression spring.

The rotary element of the switching mechanism can be designed as a stamped part or as a plate bending part. In this case the rotary element can be made of metal or of plastic.

The articulated mechanism disposed between the movable contact and the latch in order, in the event of a movement of the latch, to move the movable contact such that it can be brought into connection with a fixed contact of the electrical switching device or can be released therefrom, can be designed as a toggle.

The latching element is preferably designed such that it has a surface, along which the end of the latch facing the latching element as well as the rotary element, in particular the concentric contour of the rotary element, can run during a tensioning operation of the switching mechanism, and has a recess into which the rotary element can be inserted at the end of the tensioning operation. Preferably the latching element has a plate which is U-shaped.

The tripping mechanism of the switching mechanism can be designed in a variety of ways. A switching mechanism in which the tripping mechanism has a tripping shaft is preferable. A tripping operation of the electrical switching device can be triggered by movement of the tripping mechanism or of the tripping shaft, so that the movable contact is separated from the fixed contact of the electrical switching device. If the latch and the latching element are in the loaded position and the operating lever is in the OFF position, the tripping shaft is separated from the latching element by a gap. As a result a movement of the tripping shaft cannot result in a tripping operation of the electrical switching device, since no pressure can be exerted on the latching element via the tripping shaft. If the latch and the latching element are in the loaded position and the operating lever is in an ON position, the tripping shaft directly abuts the latching element, so that in the event of a movement of the tripping shaft, the tripping shaft moves the latching element, as a result of which the latching element releases the latching of the latch and a tripping operation is triggered. Instead of a tripping shaft a tripping latch, etc., can also be provided.

According to a second aspect of an embodiment of the invention, an electrical switching device, in particular a low-voltage circuit-breaker, includes at least one movable contact and at least one fixed contact as well as a switching mechanism for connecting and separating the at least one movable contact and the at least one fixed contact, wherein the switching mechanism is designed according to the first aspect of an embodiment of the invention. Such an electrical switching device, such as a low-voltage circuit-breaker, accordingly has the same advantages as have been fully explained according to the first aspect for the switching mechanism.

FIGS. 1 to 9schematically show a switching mechanism30of an electrical switching device, in particular of a low-voltage circuit-breaker, which is designed according to an embodiment of the inventive design principle. The switching mechanism30has an articulated mechanism20for moving a movable contact (not shown). The articulated mechanism20can be designed as a toggle. The articulated mechanism20is in operative contact with a latch1of the switching mechanism30. This means that the articulated mechanism20of the switching mechanism30is actuated by a movement of the latch1, so that in a first position of the latch1, known as the trip position of the latch1, the articulated mechanism20is moved such that the movable contact coupled to the articulated mechanism20is separated from a fixed contact (likewise not shown) of the electrical switching device. In this state the electrical switching device disconnects a consumer from a voltage supply network. In a second position of the latch1, known as the tensioned position GS, the articulated mechanism20is rotated by the latch1such that the movable contact contacts the fixed contact, so that the electrical switching device permits a flow of current to a consumer.

The latch1is rotatably mounted about a fixed latch spindle24. In this case the latch spindle24can be disposed at an end of the latch1, as shown inFIGS. 1 to 9. Alternatively it is possible for the latch spindle24to be disposed centrally or approximately centrally on the latch1. The latch1further has a clamping cam6. The switching mechanism30further has an operating lever21for manually opening and closing the movable contact via the articulated mechanism. The operating lever21has a grip14and a terminal link23which can be pivoted about a fixed bearing point. Provided on the operating lever21is a tensioning element12, in particular in the form of a spring element, which in the event of a movement of the operating lever21and thus of the latch1is tensioned, so that it exerts a force on the latch1. This means that the tensioning element12is disposed on the operating lever21and the latch1such that in the event of a movement of the operating lever21it is tensioned from an ON position to an OFF position and as a result exerts a force on the latch1.

A tensioning roller10, which can be driven via the operating lever21, rolls along the clamping cam6of the latch1in the event of a movement of the operating lever21. This means that the tensioning roller10is in continuous operative contact with the latch1. In the position of the operating lever21shown inFIG. 1, i.e. in the ON position of the operating lever21, the latch1is in an upper position, in which it is released. The tensioning roller10is rotatably movably attached to the terminal link23of the operating lever21.

The latch1has an end25cooperating with a latching element7of the switching mechanism30, which end is used for latching and unlatching the latch1on the latching element7. In this case the latch1or the end25of the latch1can latch onto the latching element7.

The switching mechanism30further has a tripping mechanism18, in particular in the form of a tripping shaft, which in order to move the latching element7can be brought into operative contact therewith. Disposed between the latching element7and the tripping mechanism18is a force element8, in particular in the form of a leg spring. The force element presses the tripping mechanism18and the latching element7apart, wherein the force element8applies a force in the direction of the end25of the latch1to the latching element7.

The switching mechanism30further has a rotary element4which is movably held on a bearing2and on a sliding block guide3of the latch1. In this case the rotary element4can be rotated about an axis of rotation on the bearing2. During the rotary movement the rotary element4is guided in the sliding block guide3. The sliding block guide3inside the latch1or inside the end25of the latch1here restricts the rotary movement of the rotary element4. The rotary element4is designed such that it can be brought into operative contact firstly with the tensioning roller10and secondly with the latching element7.

The latch1or the end25of the latch1, the rotary element4, the latching element7as well as the tensioning roller10cooperate during a tensioning operation of the latch1.

FIG. 2shows the force element8which is disposed between the latching element7and the tripping mechanism18. In this case the force element8presses the latching element7against the end25of the latch1or depending on the position of the latch1against the rotary element4.

In the positions of the switching mechanism30shown inFIGS. 1 and 2the force element8presses the latching element7against the latch1or against the end25of the latch1. In this position the operating lever21is in an ON position.

FIG. 3shows the switching mechanism30according toFIG. 1during the tensioning operation9, i.e. during the movement of the operating lever21from the ON position to the OFF position. This movement corresponds to the tensioning operation9to transfer the latch1and the latching element7to the loaded position GS. During this tensioning operation9the tensioning roller10rolls along the clamping cam6of the latch1and moves it downward. The clamping cam6, i.e. the contour of the latch1facing the tensioning roller10, predetermines the degree of movement of the latch1. This means that during the tensioning operation9, operating lever21from “TRIP” to “RESET”, the tensioning roller10moves upward on the clamping cam6. In this case the rotary element4can be pushed back by the tensioning roller10. This is shown inFIG. 5. If the tensioning roller10moves upward on the clamping cam6of the latch1the tensioning roller10presses the rotary element4below the line of the clamping cam6. On reaching the OFF position (“RESET”) of the operating lever21the rotary element4jumps back, under the effect of force exerted by the latching element7, into its original position11, seeFIG. 4. In this original position11of the rotary element4the rotary element4overlaps the clamping cam6of the latch1. Thus in this original position11, also known as the neutral position, at least a part of the rotary element4, in particular a keep-out area13of the rotary element4, overlaps the clamping cam6of the latch1. This original position11is necessarily reached by the pressure of the latching element7which is applied by the force element8.

FIG. 6schematically shows an enlarged illustration of the tensioning roller10, the clamping cam6, the latch1and the rotary element4. The rotary element4has a function area, known as the keep-out area13, at one end. If the tensioning roller10moves to the end of the clamping cam6, the tensioning operation9is concluded. The tensioning roller10no longer contacts the rotary element4, so that the latter, because of the pretensioning which the latching element7exerts on the rotary element4, jumps back to its original position11, in which at least the keep-out area13of the rotary element4overlaps the clamping cam6of the latch1. This overlap position, i.e. the original position11of the rotary element4, is shown inFIGS. 4 and 7.

After release of the grip14of the operating lever21the tensioning roller10moves back on the clamping cam6, under the effect of the force of the tensioning element12on the latch1, and stays on the keep-out area13of the rotary element4under pressure. The rotary element4or the keep-out area13of the rotary element4is designed such that the forces, i.e. the friction forces between the tensioning roller10and the keep-out area13of the rotary element4and those of the tensioning element12, are in equilibrium, as a result of which the operating lever21stays in the OFF position and at the same time the loaded position GS is reached.

FIG. 8schematically shows an enlarged illustration of the loaded position GS of the latch1or of the latching element7. The latching element7has a recess, into which a part of the rotary element4is inserted. This means that the concentric contour27of the rotary element4slides along the latching element7, until this concentric contour27reaches the recess of the latching element7. After reaching the recess the rotary element4does not move in the direction of the latching element7, but the latching element7moves in the direction of the rotary element4. A gap15hereby arises between the latching element7and the tripping mechanism18. This means that while the rotary element4or the keep-out area13of the rotary element4holds the tensioning roller10and thus the operating lever21in the OFF position, a gap15exists between the latching element7and the tripping mechanism18. In this loaded position GS of the latch1and of the latching element7the tripping mechanism18can be actuated, without a tripping operation of the switching mechanism30being performed, as no pressure can be exerted by the tripping mechanism18on the latching element7.

Thus the electrical switching device can be supplied by a manufacturer to a customer in such a loaded position GS of the latch1and of the latching element7as well as in the OFF position of the operating lever21, wherein it is ensured that these positions are maintained even in the event of an undesired movement of the tripping mechanism18. The tensioning roller10is held under pressure on the keep-out area13of the rotary element4. The forces acting in the switching mechanism30, in particular the friction force between the tensioning roller10and the keep-out area13as well as the force of the tensioning element12acting on the latch1, are here in equilibrium.

If the operating lever21moves from the OFF position to the ON position, wherein the movement is triggered manually by a user of the electrical switching device, the tensioning roller10, which is advantageously rotatably movably disposed on the terminal link23of the operating lever21, lifts up from the keep-out area13of the rotary element4, as a result of which the latch1, under the effect of the tensioning element12, is moved upward. This movement is restricted by the end25of the latch1touching the latching element7.

Thus after the switch-on operation of the switching mechanism30or of the operating lever21forces of at least one pole unit of the electrical switching device and of the tensioning element12act on the latching element7. These forces17generate a torque16in the bearing of the latching element7, as a result of which a defined force19can be generated onto the tripping mechanism18, wherein a tripping operation is then enabled. This means that after the tensioning roller10has been moved away from the rotary element4, the latch1or the end25of the latch1latches onto the latching element7, so that the latch1is further kept in a loaded position GS. If the tripping mechanism18is now actuated by a trip (not shown) of the electrical switching device, the tripping mechanism18can, because of the direct contact with the latching element7, move the latter such that the latching of the latch1onto the latching element7is released, so that the electrical switching device can trip and the movable contact is separated by the switching mechanism30from the fixed contact of the electrical switching device.

FIG. 10schematically shows a perspective illustration of a switching mechanism30of an electrical switching device, in particular of a low-voltage circuit-breaker. The rotary element4is designed in two parts. This means that the rotary element4has a first base body which is disposed on a first side of the latch1, and a second base body which is disposed on the other side of the latch1. The two base bodies of the rotary element4are connected to one another by two bolts. In this case one bolt is mounted on a bearing2(not shown) on the latch1and the second bolt is guided in the sliding block guide3of the latch1. Part of the rotary element4is inserted into a recess of the latching element7. In this position of the rotary element4the part of the rotary element4with the keep-out area13overlaps the clamping cam6of the latch1. The latching element7is, because of the spring force of the leg spring8, pressed against the rotary element4so that a gap15, seeFIG. 8, arises between the rotary element4and the tripping mechanism18.

References back that are used in dependent claims indicate the further embodiment of the subject matter of the main claim by way of the features of the respective dependent claim; they should not be understood as dispensing with obtaining independent protection of the subject matter for the combinations of features in the referred-back dependent claims.

Furthermore, with regard to interpreting the claims, where a feature is concretized in more specific detail in a subordinate claim, it should be assumed that such a restriction is not present in the respective preceding claims.

LIST OF REFERENCE CHARACTERS

1Latch2Bearing3Sliding block guide4Rotary element5Overlap6Clamping cam7Latching element8Force element9Tensioning operation10Tensioning roller11Original position12Tensioning element13Keep-out area14Grip15Gap16Torque17Force of pole unit or tensioning element18Tripping mechanism19Force on tripping mechanism20Articulated mechanism21Operating lever22Recess23Terminal link24Latch spindle25End of the latch26Tripping shaft27Concentric contour on the rotary element30Switching mechanismGS Loaded position of the latch/latching elementON ON position of the operating leverOFF OFF position of the operating lever