Patent Number: 044629559
Section: summary

FIELD OF THE INVENTION The invention relates to a support device positioned between an element of large mass and a fixed support, enabling the movements and the accelerations of the element with respect to the support to be limited, during movements caused by stresses such as those arising from an earthquake. BACKGROUND OF THE INVENTION In the construction of structures or in the positioning of machines, it is necessary to support structures or equipment of heavy mass on fixed supports such as foundations or support slabs. For example, support devices are known designed to transmit forces between the supported element and the support which are constituted by anchorages or articulations. These devices transmit the forces integrally between the bearing structure and the borne element. This presents drawbacks in particular in the case where large stresses such as those accompanying an earthquake are transmitted to the supported element. In particular, in the case of construction of nuclear reactors, for safety reasons one may be led to avoid the use of such support devices which can place the supported structures or equipment in danger, in the case of a considerable stress coming, for example, from the ground. More elaborate support devices have therefore been conceived which absorb or limit such forces. For example, the use of flat or curved sliding pads or of pads associated with stops or energy absorbers has been proposed. Devices including support parts forming bearing tracks and elements such as balls have also been proposed, assuring in association the support of the structure. Devices have been conceived, for example, associating two disks having concave surfaces with balls arranged between these two concave surfaces and pendular yokes with a spherical journal, for the support of structures or machines in order to reduce the forces transmitted to the borne element from the support. If these devices indeed reduce the forces transmitted, they can only limit the relative movements of the bearer elements and of the borne element by the use of stops or energy absorbers, to avoid too large a deformation of the borne element. On the other hand, systems with balls or with spherical bearings, if they have a good reaction to forces of any direction, are unusable as soon as the borne mass exceeds a certain threshold, i.e., when support by contact on a small surface is not possible. SUMMARY OF THE INVENTION It is an object of the invention, therefore, to provide a support device arranged between an element of large mass and a fixed support, enabling the movements and accelerations of the element with respect to the support to be limited, during movements caused by stresses such as those arising from an earthquake, comprising bearing elements arranged between support parts forming tracks for the bearing elements inclined with respect to the horizontal plane and assuring the transmission of the vertical forces of inertia from the element to the support. The support device must permit reduction of the forces transmitted to the borne element of large mass while avoiding large movements of excessive amplitude, whatever the direction and origin of the forces exerted between the support and the borne element. For this purpose, the support device according to the invention comprises: bearing elements constituted by cylindrical rollers arranged horizontally on superposed sets of at least two rollers, the rollers of one set having their axes perpendicular to the axes of the rollers of the other set, PA0 and a set of three support parts totally independent of one another, comprising a first support part on which the borne element rests directly and supported on the upper set of rollers, a second part on which rests the upper set of rollers and supported on the lower set of rollers, as well as a third support part resting on the fixed support and supporting the lower set of rollers, the first support part having a bearing track on its lower surface, the third part having a bearing track on its upper surface, and the second support part having a track on both its upper surface and its lower surface. In order that the invention may be more clearly understood, there will now be described, with reference to the accompanying drawings, an embodiment of a support device according to the invention applied to the support of racks of fuel elements on the bottom of the storage pool of a pressurized water nuclear reactor.