Joints and connections – Member ends joined by inserted section – Laterally inserted section
Reexamination Certificate
2001-10-29
2004-02-17
Browne, Lynne H. (Department: 3679)
Joints and connections
Member ends joined by inserted section
Laterally inserted section
C403S292000, C403S278000, C403S279000, C200S050320, C200S293000, C200S303000, C200S307000
Reexamination Certificate
active
06692181
ABSTRACT:
FIELD OF THE INVENTION
The invention generally relates to a connecting apparatus including a first component and a second component, as well as a connecting element. Preferably, the components include enclosure parts or shells of switching devices which are installed in a row or low-voltage switching devices, for example of circuit breakers.
BACKGROUND OF THE INVENTION
Circuit breakers and other devices which are installed in a row, as well as their enclosure parts or halves, are normally connected via one or more poles by nuts and bolts, clips or brackets, or rivets. One enclosure shell and one cover shell typically have to be connected to one another for each pole. It is intended to be possible firstly to produce such connections cost-effectively and simply, such that they can be installed easily. Secondly, compression loads which occur as a consequence of arching influences are intended to be absorbed by the connections, and tolerances are intended to be compensated for, while allowing the enclosure shells to expand and ring when subjected to environmental conditions. A specific prestressing force is also intended to be exerted on the enclosure shells in order not only to ensure that the parts to be connected are protected against twisting, but also to ensure that the connection is protected against being inadvertently loosened.
While the use of a screw connection for connecting the components or enclosure shells to one another is, firstly, costly and, secondly, the screw connection must be secured against inadvertently becoming loose, for example by using varnish, a riveted joint offers only a small amount of compensation for tolerances in its longitudinal direction.
This is particularly true when the tolerances to be compensated for are additive. Furthermore, riveted joints easily bend when carrying out a riveting process using relatively long rivets. In addition, additional centering pieces have frequently been used in the past to protect the individual poles against twisting, even though this results in additional manufacturing and production costs.
At least two clips or brackets must be used, in a likewise costly manner, for a clip or bracket joint, which is likewise frequently used. In this case, the poles are firstly braced with respect to one another with only a small clamping force while, secondly, the clips or brackets can easily become loose, resulting in the risk of manipulation. A bonded joint, which has likewise been used in the past, does not allow the individual components to be dismantled without destroying them and, furthermore, does not ensure that the components are adequately braced with respect to one another.
A connecting element which is manufactured from a flat strip material is known from German Utility Model DE 83 22 594 A1, and this can also be used for circuit breakers having an elongated shaft, whose two shaft ends are T-shaped by means of integrally formed tabs. In order to insert the known connecting elements into the mutually aligned through-openings or holes in the components to be connected, one of the shaft ends is slotted such that the T-shaped holding or fixing tabs can be interlaced in the direction of the shaft longitudinal axis. This admittedly results in this shaft end being matched to the shaft width. However, this configuration necessarily leads to the cross section of the shaft, and hence the connecting element, being weakened, with the consequence that the cross section must be deliberately weakened over the entire shaft length by equidistant holes. Admittedly, it makes it possible to achieve a uniform material load and to avoid any weak point. However, this weakening of the cross section leads to a considerable reduction in the shaft cross section that can be loaded and hence to a reduction in the bracing force which is intended to be achieved by twisting the shaft, resulting in the length of the connecting element being reduced. Furthermore, during the twisting process, the entire slot, which is lengthened by means of an elongated hole, must be covered by a tool at the corresponding shaft end, and the opposite shaft end must be held in order firstly to secure this shaft end against rotation at the same time and, secondly, in order to achieve a tensile force, and hence a bracing force, which is as uniform as possible at the shaft ends. Furthermore, the complicated bending-in and bending-out mechanism with the slotted shaft end means that a number of twisting operations are required in order to ensure that the length of the connecting element is reduced sufficiently to brace the components.
SUMMARY OF THE INVENTION
The invention is thus based on an object of specifying a connecting apparatus of the type mentioned initially in which the disadvantages are avoided.
According to the invention, an object is achieved by the features of claim 1. To this end, a first mounting depression, which holds the holding end and is aligned with the through-openings, has a centering cone, the holding end-being conical, forming a mating surface which corresponds with the centering cone.
In consequence, the process of twisting the connecting element in order to brace the components firstly results in centering and secondly in a particularly short turning or twisting distance, without the material cross section being weakened along the shaft at the same time. Furthermore, in addition to reliable self-centering of the connecting element, which is preferably manufactured by stamping from a flat strip material, within the mutually aligned through-holes in the components, a tensile force which is uniform across the cross section of the connecting element is exerted on the opposite shaft end when a connecting element is twisted. In this case, this shaft end, which is also used as an insertion end, is inserted in a positively locking manner in a corresponding (second) mounting depression in the mounting state and before the connecting element is twisted.
In order to produce the positive lock for that shaft end which is opposite the conical holding end and is also used as the insertion end, it may be T-shaped with two fixing lugs. In this embodiment, diametrically opposite guide slots are provided in the through-openings in the components, in which guide slots the insertion end, and hence the two fixing lugs, are guided while the connecting element is being pushed through the through-openings.
In one particularly advantageous refinement, the connection in this variant is in the form of a bayonet fitting. To this end, when the connecting element is twisted, both fixing lugs are preferably guided at the insertion end along a respective ramp-like internal contour, which is provided in the (second) mounting depression, which holds the insertion end. In the process, the connecting element is preferably latched at the end of the twisting process and is thus fixed securely and detachably while exerting the desired bracing force. The ramp-like internal contour preferably has a number of recesses corresponding to the number of fixing lugs at the ramp end, into which recesses the fixing lugs are latched. In order to increase the bracing force further when the connecting element is in this fixing position, the shaft can also be twisted, so that its length is shortened. However, only a short torsional movement is then advantageously required for this purpose, with a half-twist or single twist. The ramp-like internal contour preferably extends over an angle of between 90° and 180° for each fixing lug, with the internal contour corresponding to a corresponding ramp circular segment.
In one alternative embodiment, the fixing lugs at the T-shaped insertion end are first of all bent inwards in the form of a circular arc, in an initial state, in order to match the external dimensions of the shaft. In the mounting state, that is to say once the connecting element has been inserted into the through-openings, the bent-in fixing lugs are bent radially outward. In order to allow the fixing lugs at the insertion end to be bent out outside the component or enclosure part facing th
Franz Bernhard
Leitl Wolfgang
Schmid Josef
Browne Lynne H.
Ferguson Michael P.
Harness & Dickey & Pierce P.L.C.
Siemens Aktiengesellschaft
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