Voltage source converters

A spring arrangement for operating a high and medium voltage circuit breaker comprising a cylindrical housing having a main axis, an actuation rod, a coil spring arranged in the cylindrical housing, coupled with the rod, and a coupling arrangement coupling an end of the spring with an end of the rod, wherein the coupling arrangement comprises an articulation for guiding an end of the rod in rotation with respect to the second end of the spring around a second axis perpendicular to said main axis and comprises sliding means for the translational guiding of the second end of the rod along said main axis.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a spring arrangement for a spring drive unit, e.g. for driving and controlling the opening and closing of an electrical switching apparatus, such as a switch or a circuit breaker.

The said switching apparatus is meant to be used in a high or a medium voltage transmission or distribution network.

BACKGROUND OF THE INVENTION

Spring arrangements, for example for a high- or medium-voltage circuit breaker, comprise compression springs to store an amount of energy to be released when the mechanism is operated.

The compression spring is linked to a rotating shaft of the apparatus by a flexible connection, to allow the action of the spring to be converted into a rotary action around the shaft's main axis.

An example of such a solution comprises a transmission shaft, both ends of which being articulated with the rotating shaft and a moving end of the compression spring, respectively.

The moving end of the spring is displaceable inside a cylindrical housing.

However, due to lateral forces on the moving end of the spring, the apparatus can sometimes jam. Moreover, the guiding surfaces must be made with the best surface finish.

An objective of an embodiment of the invention's goal is to provide a spring arrangement with enhanced means for guiding the mobile end of the spring inside the housing.

SUMMARY OF THE INVENTION

An embodiment of the invention concerns a spring arrangement for operating a high and medium voltage circuit breaker comprising a main frame comprising a cylindrical housing having a main axis A, an actuation rod, a first end of which being coupled to a rotary shaft of the circuit breaker, the second end of the rod being movable in the cylindrical housing along its main axis A, a coil spring arranged in the cylindrical housing and coaxially to main axis A, wherein a first end of the spring is mounted on the frame and the second end of the spring is coupled with the second end of the rod, and a coupling arrangement coupling the second end of the spring with the second end of the rod, wherein the coupling arrangement comprises an articulation for rotational guidance of the second end of the rod with respect to the second end of the spring around a second axis B perpendicular to said main axis A, which is located axially, along main axis A, at the second end of the spring and wherein the coupling arrangement comprises sliding means for the translational guiding of the second end of the rod along said main axis A.

In an embodiment, the coupling arrangement comprises a support plate mounted on the second end of the spring, the support plate is linked to the second end of the rod by said articulation and is linked to the housing by the sliding means.

In an embodiment, the coupling arrangement comprises at least one shaft coaxial to said second axis B, by means of which the support plate is pivotally linked to the second end of the rod.

In an embodiment, the second end of the rod is mounted on a plate articulated with respect to the support plate, around said second axis B by means of said at least one shaft.

In an embodiment, the coupling arrangement comprises at least one shaft coaxial to said second axis B, by means of which the support plate is linked to the sliding means.

In an embodiment, a portion of said shaft extends through the support plate and one end of the shaft is received in a groove of housing's wall, which is parallel to said main axis A.

In an embodiment, said end of the shaft supports a sliding shoe which is received in the groove, for lowering the friction between the shaft and the groove.

In an embodiment, said shaft extends radially from said main axis A, the radially internal end of the shaft being linked to the articulated plate by means of bearings and the radially external end of the shaft being received in the groove of the housing's wall.

In an embodiment, the arrangement comprises two coaxial shafts placed on both sides of said main axis A, the radially internal end of each shaft being linked to the articulated plate by means of bearings and the radially external end of each shaft being received in the groove of the housing's wall.

In an embodiment, the arrangement further comprises an adjusting bolt screwed on the second end of the rod, the adjusting bolt being in contact with a face of the articulated plate, which is opposite to the spring.

DETAILED DESCRIPTION OF THE INVENTION

The drawings represent a part of a spring arrangement10for driving and controlling the opening and closing of an electrical switching apparatus (not shown) like for example a high- or medium-voltage circuit breaker.

The arrangement10comprises a spring12for storing an amount of energy which is to be used for driving the switching apparatus.

The spring12is more particularly a coil spring, having a main axis A and it is received in a cylindrical housing14formed in a main frame16.

The housing14is coaxial to main axis A of the spring12and is opened at its end close to the switching apparatus.

A first end12A of the spring12, here on the top right of the drawings, is located at the mouth (not shown) of the housing. This first end12A of the spring12is fixed to the open end of the housing14by any known means. For example, the first end of the spring12is in abutment against a radial collar mounted at the end of the housing14. The first end12A of the spring12is then immobile.

The second end12B of the spring12is movable inside the housing14along main axis A of the spring12.

The arrangement10also comprises a transmission rod18for transmitting the energy stored in the spring12to the circuit breaker.

A first end (not shown) of the rod18is linked to a rotating shaft of the circuit breaker.

The second end18bof the rod18is linked to the second end12B of the spring12.

The connection between the second end18bof the rod18and the second end12B of the spring12is realized by a coupling arrangement20that is designed to permit an oscillation of the rod18with respect to the second end12B of the spring12around a second axis B oriented radially to main axis A of the spring12.

The coupling means20are also designed in order to provide translational guidance of the second end12B of the spring12along main axis A, inside the housing.

The coupling means20comprise a support plate22fixedly mounted on second end12B of the spring. The support plate22is located inside the housing14and is linearly movable herein.

The support plate22extends in a radial plane, orthogonal to main axis A of the spring12and its shape corresponds to the radial section of the housing14across a radial plane.

The support plate22is articulated to the second end18B of the rod18and is linearly guided within the housing14.

The support plate22comprises a central opening26centered on main axis A, in which an articulated plate24is received.

The articulated plate24is fixed to the second end18B of the rod and is pivotally mounted on the support plate22around secondary axis B.

The articulation means also comprise at least one shaft28coaxial with secondary axis B, which is fixedly mounted in a complementary hole30of the support plate22.

Here, the arrangement10comprises two shafts28which are coaxial to secondary axis B and which are placed on both sides of said main axis A. however, it will be understood that the arrangement can comprise only one shaft28.

Each shaft28extends radially from main axis A. A first end28aof the shaft28, located radially inwards, is located in the central opening26of the support plate22and is pivotally mounted in a corresponding hole32of the articulated plate24, by means of bearings34, e.g. needle bearings.

Then, while the arrangement10cooperates with the circuit breaker, the shaft28is free to oscillate around secondary axis B, while the second end12B of the spring12and the second end18B of the shaft translate along main axis A.

The support plate22is also guided in translation in the housing14along main axis A.

The guiding means comprise sliding shoes36, here two sliding shoes placed on both sides of main axis A, which are mounted on the support plate22. Each sliding shoe36is received in a respective groove38made in a wall40of main frame16.

The groove38extends parallel to main axis A and is open radially facing main axis A.

The sliding shoes36are made of a material with good gliding performances. For example, the sliding shoes are made of polytetrafluoroethylene (PTFE), or of polyethylene (PE).

Each sliding shoe36is mounted on a second end28B of the shaft28which extend radially outwards from the peripheral edge of the support plate22.

Then, each shaft28comprises a first end28A located radially inwards, which is received in a corresponding hole32of the articulated plate24, a central part28C received in a complementary through hole30of the support plate22and a second end28B extending radially outwards from the peripheral edge of the support plate22, on which a sliding shoe36is mounted.

The coupling means20also comprise means for adjusting the length of the rod18, in order to adjust the force exerted by the spring12on the rod and on the rotating shaft of the circuit breaker.

The adjusting means comprise a bolt42which is in contact with a radial face24A of the articulated plate24. This radial face24A is located opposite to the spring12.

The bolt42further comprises a threaded sleeve44in which the second end18B of the rod18is screwed.

Then, by screwing or unscrewing the bolt42on the rod18, the pretension of the spring12can be adjusted.