The invention relates to a connecting element for connecting, for passage of a fluid, a first rigid component adapted for guiding the fluid to a second rigid component adapted for guiding a fluid arranged rotatably about a rotation axis relative to the first rigid component arranged for guiding the fluid.

Such connections are generally known in the form of connections of flexible conduits. Although flexible conduits have become available in recent years which have excellent properties in respect of pressure resistance and temperature resistance, there is a need for rigid conduits for the purpose of some applications, for instance because these have better thermal insulation.

The object of the invention is to provide such a connection which makes use of rigid conduits, but which nevertheless enables relative rotation between the components while maintaining sealing.

This object is achieved with such a connecting element, wherein the at least one tube is manufactured from substantially rigid material, the tube is connected by a rigid connection to at least one of the components adapted for guiding a fluid, and the tube extends at a distance from the rotation axis. This configuration makes it possible to deform the at least one tube outside the rotation axis of the relative rotation between the two components. The rotation of the tube also always involves a translation, whereby the deformation of the tube differs from that of a pure torsion of the tube. Owing to this difference the rigid tube can accommodate the rotation with less deformation, so reducing the danger of leakage or breakage.

Although it is possible in principle to arrange the rigid connection only on a single side, it is more attractive for the tube to be connected by a rigid connection to both components adapted for guiding a fluid. The deformation caused by the rotation is distributed over still more directions when the axis of the at least one rigid connecting tube intersects a flat plane extending through the rotation axis. The deformation of the tube then comprises not only a rotation and a translation, but also another further movement .

The deformation is further reduced when the at least one rigid connecting tube extends in a helix. The rotation is hereby at least partially accommodated by the diameter of the helix being decreased.

The helix preferably has a rotation angle greater than 360°, whereby the deformation is distributed over a greater length of the tube.

An alternative embodiment provides the measure that the at least one rigid connecting tube extends in a straight line. The attractive distribution of the stresses and deformation over a greater length is hereby not obtained as in the foregoing embodiment, although a considerable quantity of material is however saved. The stress in the tube caused by rotation of the components is concentrated in the vicinity of the attachment of the tube to the relevant component. In order to make this attachment as durable as possible, it is recommended that the rigidity of the at least one connecting tube decreases from the rigid connection to one of the parts toward the middle of the at least one rigid connecting tube.

Yet another preferred embodiment provides the measure that the device comprises at least two rigid connecting tubes. It hereby becomes possible to apply tubes of a smaller diameter, so that the stresses are better distributed. This advantage is increased when the number of tubes is greater than two.

The use of more tubes provides the option of them all being adapted for transport of fluid in the same flow direction.

It is however also possible for at least one of the rigid connecting tubes to be adapted for transport of the fluid in opposite direction to that of other rigid connecting tubes . The invention will be elucidated hereinbelow on the basis of the accompanying drawings, in which: figure 1 is a perspective, partially broken-away view of a first embodiment of the invention; figure 2 is a perspective view of a second embodiment of the invention; and figure 3 shows a mobile solar collector with a connecting element according to the invention in a third embodiment.

Figure 1 shows a connection between a first component 1 and a second component 2. Both components are adapted to be able to rotate relative to each other about the axis extending through both components and indicated with a dot-dash line 3.

Both components form a part of the same device, wherein the construction of the device requires that parts 1, 2 are rotatable relative to each other in collinear relation. The construction of the device likewise requires that a liquid or a gas is transported between the two components 1, 2. It is assumed that the transport takes place in a single direction, although it is also possible for the transport to take place in two opposite directions, i.e. the flow direction in a number of tubes, for instance five of the tubes, is opposite to that in the remaining five tubes.

For the purpose of transporting the fluid a number of tubes 4a-4j are arranged, in the present case ten, each extending between component 1 and component 2. A respective cavity 5, 6 is arranged in components 1, 2. Tubes 4a-4j are each connected by a rigid connection to both components 1,

2, wherein the interior of the tubes connects to cavities 5 and 6. As a consequence of the rigidity of tubes 4a-4j a rotation between the two components 1, 2 is accommodated by tubes 4a-4j deforming along their whole length, wherein it is noted that this distribution is improved when the rigidity of the at least one connecting tube decreases from the rigid connection to one of the parts toward the middle of the tubes. It is noted that all tubes extend at a distance from rotation axis 3, and that they extend to some extent obliquely, i.e. they each intersect a plane extending through rotation axis

3. Although this embodiment can in principle be implemented with a single connecting tube, it will be apparent that at least two tubes will usually be used in order to obtain a symmetrical construction. During rotation it is not possible in some circumstances to prevent the occurrence of some associated second-order length effect. This effect will be negligibly small in practice, particularly in the case where the effective rotation angle per unit of length of the tubes is small- It will be apparent in this respect that the known laws of physics which describe the torsion are applicable to the situation according to the invention. It will thus be apparent that in the embodiment according to figure 1 the torsion angle per unit of length of the tubes will be greater for a given overall torsion angle than in the embodiment according to figure 2, in which the overall length of the tubes is substantially greater than in the embodiment according to figure 1. Attention is further drawn to the fact that parts 1, 2 could be embodied such that they mutually connect two respective groups of tubes in the manner of multiple manifolds such that the one group of tubes transports medium in the one direction, while the other group of tubes transports medium in the other direction. This is essentially a multiple form of the embodiment according to figure 2.

Figure 2 shows an embodiment wherein two helical tubes 7a, 7b are placed between components 11 and 12. Owing to the small pitch of the helix a large number of windings are present, so that tubes 7a, 7b are both long. The deformation caused by the relative rotation of the components is hereby distributed over a great length, so that the deformation per length of tube remains small. This distribution is also improved in this embodiment when the rigidity of the at least one connecting tube decreases from the rigid connection to one of the parts toward the middle of tubes 7a, 7b. Because the flow of the fluid takes place in two opposite directions in this embodiment, each of the components is provided with two channels 13, 14 and 15, 16 respectively for guiding the fluid in both flow directions.

It will also be apparent that the measures of the two embodiments can be combined.

Figure 3 shows a mobile solar collector 20 of the type described in applicants non-prepublished Netherlands patent application NL-2002960. Use is made in solar collector 20 of a connecting element according to the invention. An in and outward foldable mirror consisting of two parts 21, 22 is supported by a sub-frame 23 which is pivotable as according to an arrow 24 relative to a main frame 24. The solar radiation from the sun is concentrated by mirror 21, 22 on a tube 25 through which heat transport medium can flow such that the medium present therein is heated by the solar radiation. The medium is transported through tube construction 25 by means which are not shown. Because the angular position of mirror 21, 22 relative to that of main frame 24 is chosen subject to the position of the sun, the medium flowing through tube construction 25 must flow over a certain pivoting range with main frame 24.

Because of the very high temperatures which can be reached with this type of solar collector, the use of sealing rotation couplings is not practical. Use is therefore made in this embodiment of a connecting element according to the invention. This is embodied largely in the same manner as shown in figure 2, with the proviso that tubes 26, 27 have a slighter helical form than in figure 2, so have in this respect a form akin to that of the tubes according to figure 1.

In this embodiment there are only two tubes 26, 27. In the structure according to figure 3 the connecting parts 1, 2 or 11, 12 (not shown) are coupled non-movably to respectively the main frame 24 and the sub-frame 23 disposed pivotally relative thereto.

Not shown is that in a practical embodiment the tubes 26, 27 are protected during operation by a protective sleeve. Not shown either are the pump means required for transporting the medium and the connection of solar collector 20 to a user station and, to the extent necessary, power supply means whereby the solar collector can automatically follow the position of the sun as it varies during the day in order to achieve the highest possible efficiency of the solar collector.