More specifically, the invention concerns a separable coupling that comprises a number of clamps by means of which an encircling strap is pressed against flanges on the vessel part and the protective envelope. The vessel part and the protective envelope are held together by the encircling strap. When the encircling strap is released, the protective envelope separates from the vessel part.

STATE OF THE ART When satellites are launched for placement into orbit around the earth, the sensitive satellite equipment is protected from the atmosphere by a protective envelope, or"fairing".

This envelope is fastened to the launch rocket or a so-called a"launcher part"of the launch rocket. To ensure that the protective envelope can be easily removed from the space vessel without risk of damage to the vessel part or the satellite equipment, the protective envelop consists of two or more parts, which are joined by means of a coupling device. When the parts of the protective envelope are separated from the rocket, all acceleration of said parts ceases, while the acceleration of the rocket continues. The parts of the protective envelope fall down toward the atmosphere and burn up.

The coupling device constitutes an important structural element for absorbing the forces at work between the vessel part and the protective envelope during the launch of the space vessel. The coupling device must be of low weight, and it must be designed for extremely high reliability, given the extremely high cost of such launches. Any faults that might arise once the vessel has left the group are impossible to rectify.

One problem associated with the design of the coupling device is that space vessels and their separable parts are subjected to loads, e. g. axial forces, torque, vibrations and tensile and compressive loads around the periphery of the space vessel.

The coupling devices must be designed so that, up to the time of separation, they hold the

vessel part and the protective envelope together with such force that the mutual movement between these two components is minimized. The current art utilizes a pyrotechnical linear charge around the circumference in order to shear off the structural element. These charges must be oversized in order to achieve satisfactory reliability. This result in major shock effects when the coupling is released, which can result in damage to sensitive electronics in the satellites.

A technique involving tension straps is currently used for separating satellites. This technique does not currently work satisfactorily for securing a protective envelope to a vessel part. This is due mainly to the large circumference of the space vessel, which entails that extremely high tension would be necessary in the tension strap to hold the envelope in place securely.

DESCRIPTION OF THE INVENTION The object of the invention is to solve one or more of the aforementioned problems. This is achieved by means of a device according to claim 1.

A vessel part and a protective envelope that is separable from the vessel part are held together by a coupling, which comprises a first outer flange arranged on the vessel part, a second outer flange arranged on the protective envelope, a number of clamps, and a tension element surrounding said clamps. The vessel part further comprises a radially inwardly oriented first inner flange. This is integrally realized with one or more surrounding elements, which at least partially surround a radially inwardly oriented second inner flange on the protective envelope.

In one embodiment of the invention, the surrounding element extends uninterrupted along a periphery of the vessel part, and is in engagement with the first inner flange along the entire extent of the flange.

In one advantageous embodiment of the invention the surrounding element is in engagement with the first inner flange in a plurality of areas distributed along the periphery of the flanges, which areas are separate from one another.

In yet another embodiment of the invention, said surrounding elements comprise a plurality

of clamping lips. When the tension element is mounted around the clamps, the clamping lips are pressed against corresponding upper contact surfaces on the second inner flange of the protective envelope. The surrounding element with its clamping lips contributes to fixedly secure the inner flange of the envelope in both the radial direction and the longitudinal direction.

In one advantageous embodiment of the invention, the protective envelope may surround one or more satellites, which are held together with the vessel part.

The purpose of the coupling is to absorb divisive forces that arise between the vessel part and the protective envelope during launching of the space vessel, and while maneuvering in orbit up until the moment of separation. Designing inner flanges with an integrated surrounding element produces a coupling in which coherence and separation can be achieved without overly high stress in the surrounding tension element. Owing to the design of the surrounding element, the inner flanges constitute a new supporting and load- bearing element in the coupling.

DESCRIPTION OF FIGURES The invention will be described in greater detail in exemplary embodiments and with reference to Figure 1, which shows a partial cross-section of the coupling according to the invention.

DESCRIPTION OF EMBODIMENTS A space vessel is generally designated by 1 in the drawing. The vessel comprises a protective envelope 3 that is separable from a vessel part 2, which envelope is arranged so as to surround satellite equipment arranged on the vessel part. A coupling 4 is arranged so as to hold together the two parts 2,3 during the portion of the time the coupling is used.

The coupling 4 has a first outer flange 5 on an upper part of the vessel part 2 and a second outer flange 6 on a lower part of the protective envelope 3. These flanges are radially outwardly oriented relative to a centerline through the space vessel. The coupling further has one or more clamps 7 distributed about the periphery of the flanges 5,6. A tension element 8 runs around or through the clamps 7 and presses them radially inward against the flanges 5,6.

The clamps 7 are arranged so as to connect the outer flanges 5,6 when the clamps are conveyed in over the flanges. The clamps are pressed radially inward against the outer flanges 5,6 by applying a force to the tension strap 8. The radial force is transferred by the tension strap 8 as a clamping force, which clamps the flanges 5,6 against one another.

According to the prior art, the radially active force is transferred in that the inner surfaces of the clamps have outwardly inclined relief angles. To avoid the risk of self-locking due to friction, the outer surfaces of the flanges should be inclined somewhat so that they fit by conformity into the inner surfaces of the clamps.

The coupling also has a first inner flange 9 arranged on the vessel part, and a second inner flange 11 arranged on the protective envelope. These flanges extend radially in toward an imaginary centerline through the space vessel. A surrounding element 10 is integrally realized with the first inner flange 9 and comprises a clamping lip 10a, which at least partly abuts an upper contact surface 11 la on the second inner flange 11. The second inner flange 11 is surrounded on each side by the combination of the first inner flange 9 and the surrounding element 10.

In the embodiment shown, the first inner flange 9 extends in essentially the same plane as the first outer flange 5. A support surface is thereby formed on the top of the first outer flange and on the first inner flange. A lower contact surface 1 lb on the second inner flange 11 rests on that part of the support surface that is formed by the first inner flange.

The clamping lip 10a is essential for fixedly securing the second inner flange in both the radial direction and the longitudinal direction. The clamping lip is allowed to abut against the upper contact surface 1 l a of the second inner flange. Both the surface of the clamping lip 10a that faces the second inner flange 11 and the upper contact surface 1 la are oriented at the angle p relative to the normal plane in the embodiment shown. This angle should exceed 0° to avoid the risk of self-locking due to friction. The angle p can be varied, assuming that measures are taken to eliminate the risk of self-locking in the mounted state. The two surfaces can also exhibit different angles relative to the normal plane.

In the mounted state, under load, the two inner flanges 9,11 can abut one another. When the clamps 7 are released by cutting the tensioned strap 8, the separation of the various parts is initiated. The clamps 7 that surround the outer flanges 5,6 are pressed radially outward and removed. The protective envelope 3 can be divided into at least two separable parts along a longitudinal direction of the protective envelope 3. Separation of these protective element parts begins upon the release of the tension strap 8. This movement is possible because the protective envelope 3 can be separated into at least two separate parts.

The vessel part 2 continues along the planned orbit, while the released protective envelope 3 simultaneously falls down toward the atmosphere in at least two separate parts.

LIST OF REFERENCE DESIGNATIONS Space vessel 1 Vessel part 2 Protective envelope 3 Coupling 4 First outer flange 5 Second outer flange 6 Clamp 7 Tension element 8 First inner flange 9 Surrounding element 10 Clamping lip 10a Second inner flange 11 Upper contact surface 1 la Lower contact surface 1 lb Angle ß