Energy-absorbing device, in particular for a rail-car

1. An energy-absorbing device ( 1 ), in particular for a rail-car; the device extending along an axis ( 2 ) and comprising:

an attachment member ( 3 ), which can be connected to a supporting structure;

an impact member ( 7 ), designed to withstand an impact; and

an energy-absorbing member ( 15 ), constituted by a first tube ( 16 ) and by a second tube ( 17 ), which are coaxial along said axis ( 2 ) and are made of composite material so as to collapse and absorb energy in the event of impact; said first tube ( 16 ) comprising a first attachment end ( 19 ) fixed to said attachment member ( 3 ) and a first free end ( 29 ) axially facing said impact member ( 7 ); said second tube ( 17 ) comprising a second attachment end ( 23 ) fixed to said impact member ( 7 ) and a second free end ( 33 ) axially facing said attachment member ( 3 ), and being axially slidable, during impact, guided by said first tube ( 16 ); the cross sections of said first and second tubes ( 16 , 17 ) being variable along said axis ( 2 );

characterized in that:

the thickness in the radial direction of said first and second tubes ( 16 , 17 ) decreases along said axis ( 2 ) from said first and said second attachment ends ( 19 , 23 ) towards said first and second free ends ( 29 , 33 ), respectively; and

in a non-collapsed resting condition, the axial gap between said second free end ( 33 ) and said attachment member ( 3 ) is substantially equal to the gap between said first free end ( 29 ) and said impact member ( 7 ) so that said first and second tubes ( 16 , 17 ) start to collapse simultaneously in the event of impact.

2. The device according to claim 1 , characterized by comprising first retaining means ( 30 ) that keep said second tube ( 17 ) in a fixed position with respect to said first tube ( 16 ) in the non-collapsed resting condition and can break or be released when a given threshold of axial load is exceeded.

3. The device according to claim 2 , characterized in that said first retaining means are defined by glue ( 30 ).

4. The device according to claim 1 , characterized by comprising second retaining means ( 34 ) that prevent said second tube ( 17 ) from moving axially away from said attachment member ( 3 ) in a collapsed condition during and/or at the end of impact.

5. The device according to claim 4 , characterized in that said second retaining means ( 34 ) are arranged radially between said first and second tubes ( 16 , 17 ).

6. The device according to claim 5 , characterized in that said second retaining means ( 34 ) are arranged at one of said first and second attachment ends ( 19 , 23 ).

7. The device according to claim 6 , characterized in that said second retaining means ( 34 ) comprise a lamina ( 35 ) having a first portion ( 36 ) fixed to said second attachment end ( 23 ), and a second portion ( 37 ) that rests against a lateral surface of said first tube ( 16 ) and is oriented in such a way as to:

let said second tube ( 17 ) slide freely in the case of axial translation towards said attachment member ( 3 ); and

jam against said lateral surface ( 16 ) if said second tube ( 17 ) tends to translate axially in the opposite direction.

8. The device according to claim 7 , characterized in that said lateral surface has at least one impression ( 38 ) so as to increase friction between said lateral surface and said second portion ( 37 ).

9. The device according to claim 4 , characterized in that at least one part ( 39 ; 42 ) of said second retaining means are arranged in an axial cavity defined by said first and second tubes ( 16 , 17 ).

10. The device according to claim 9 , characterized in that said second retaining means ( 34 ) comprise a deformable metal element ( 40 ; 42 ).