Deceleration device

1. A deceleration device for deceleration of a cockpit door, comprising:

a spool reel carrying a belt being wound up on the spool reel;

an elevating spindle being driven by the spool reel when the belt is being retracted from the spool reel;

at least one collet screwed to the elevating spindle;

at least one spring assembly being installed between the collet and a fixed bearing portion of the deceleration device; and

at least one energy absorbing tube surrounding the elevating spindle to come prior into contact with the fixed bearing portion than the at least one collet, to dissipate further energy by deformation of the at least one energy absorbing tube;

wherein the at least one collet is screwed towards the fixed bearing portion by retraction of the belt from the spool reel, thereby compressing only the spring assembly in a first phase, and both the spring assembly and the at least one energy absorbing tube in a second phase, whereby a reaction load is generated by the spring assembly counteracting the retraction of the belt; and

wherein the at least one spring assembly and the at least one energy absorbing tube are arranged in parallel between the collet and a fixed bearing portion.

2. The deceleration device according to claim 1 , wherein the spring assembly comprises a plurality of compression springs being situated between the collet and the fixed bearing portion and surrounding the elevating spindle.

3. The deceleration device according to claim 1 , wherein the collet is shaped in the form of a polygon in plan view having a plurality of rounded edges forming receptacles for the plurality of compression springs.

4. The deceleration device according to claim 1 , the deceleration device further comprising:

at least one cup-shaped housing comprising a profile matching the polygonal shape of the collet to allow the collet to slide into the housing;

wherein the fixed bearing portion forms part of the base of the housing, so that the plurality of compression springs being situated between the base and the collet.

5. The deceleration device according to claim 1 , wherein the elevating spindle comprises a bearing shaft being rotatably mounted in the fixed bearing portion and a threaded shaft sleeve surrounding the bearing shaft, wherein the bearing shaft, the shaft sleeve and the spool reel surrounding the elevating spindle are locked to each other by means of a single shear pin.

6. The deceleration device according to claim 2 , further comprising a plurality of spring washers having a negligible spring constant, wherein the plurality of spring washers is connected in series with the plurality of compression springs, so that during an initial rotation of the spool reel no reaction load will be generated due to the negligible spring constant of the plurality of spring washers.

7. The deceleration device of claim 1 , wherein the deceleration device is symmetrically designed comprising an elevating spindle featuring right hand and left hand threads at either side of a central portion being surrounded by the spool reel, which due to a retraction force screws a first collet towards a first fixed bearing portion thereby compressing a first spring assembly situated between the first collet and the first fixed bearing and screws a second collet towards a second fixed bearing portion thereby compressing a second spring assembly situated between the first collet and the first fixed bearing portion.

8. A cockpit door system, the system comprising a cockpit door connected to a deceleration device for use in the event of a cockpit decompression, the deceleration device comprising:

a spool reel carrying a belt being wound up on the spool reel;

an elevating spindle being driven by the spool reel when the belt is being retracted from the spool reel;

at least one collet screwed to the elevating spindle;

at least one spring assembly being installed between the collet and a fixed bearing portion of the deceleration device; and

at least one energy absorbing tube surrounding the elevating spindle to come prior into contact with the fixed bearing portion than the at least one collet, to dissipate further energy by deformation of the at least one energy absorbing tube;

wherein the at least one collet is screwed towards the fixed bearing portion by retraction of the belt from the spool reel, thereby compressing only the spring assembly in a first phase, and both the spring assembly and the at least one energy absorbing tube in a second phase, whereby a reaction load is generated by the spring assembly counteracting the retraction of the belt; and

wherein the at least one spring assembly and the at least one energy absorbing tube are arranged in parallel between the collet and a fixed bearing portion.

9. An aircraft comprising:

a cockpit door assembly comprising a deceleration device;

the deceleration device comprising:

a spool reel carrying a belt being wound up on the spool reel;

an elevating spindle being driven by the spool reel when the belt is being retracted from the spool reel;

at least one collet screwed to the elevating spindle;

at least one spring assembly being installed between the collet and a fixed bearing portion of the deceleration device; and

at least one energy absorbing tube surrounding the elevating spindle to come prior into contact with the fixed bearing portion than the at least one collet, to dissipate further energy by deformation of the at least one energy absorbing tube;

wherein the at least one collet is screwed towards the fixed bearing portion by retraction of the belt from the spool reel, thereby compressing only the spring assembly in a first phase, and both the spring assembly and the at least one energy absorbing tube in a second phase, whereby a reaction load is generated by the spring assembly counteracting the retraction of the belt; and

wherein the at least one spring assembly and the at least one energy absorbing tube are arranged in parallel between the collet and a fixed bearing portion.