IL34337A - Closing device for the nozzle of a projectile furnished with a rocket motor - Google Patents

Description

- Closing Device for the Nozzle of a Projectile furnished with a Rocket Motor npgn ynaa nssn y*V vnrt m*ao ¾t7nn The invention relates to a closing device for the nozzle, of a projectile furnished with a rocket motor and intended to be fired by means of a gun barrel and an external drive charge. A certain initial velocity is imparted to the projectile by the drive charge, and by means of the rocket motor which starts after the projectile has left the barrel, an additional velocity is ^ imparted to the projectile.

During its travel through the barrel the projectile is subjected to a very strong pressure from the combustion gases produced by the^ drive charge. The rocket motor must somehow be protected against this pressure which could otherwise damage the motor or cause it to start too early.

It is an object of the present invention to provide a closing device for the nozzle of the rocket motor of the projectile which closing device prevents the pressure, in the barrel at the firing from affecting the rocket motor but which is automatically removed from the nozzle after the projectile has left the barrel so that the rocket motor can work freely.

According to the invention the closing device comprises a cap of metal having a high tensile strength the periphery of which has a" part for making a tight contact with the mouth of the nozzle and an annular retaining member which has a first part attached to the cap and a second part to be attached to the nozzle at its outer side and a third part joining said first and second parts and having a relatively small thickness and being so, nozzle a free space is present inside said third part, whereby this part under the action of a sufficiently high outer pressure is bent inwards and is caused to rupture so that the mechanical connection between the cap and the nozzle is interrupted.

The cap is preferably made of steel while the retaining member is made of a light metals In to in-crease the resisting power of the cap against the pressure in the barrel the cap is preferabl cup-shaped and has:. e.g. · ■ the form of a semisphere with the concave side facing the mouth of the nozzle.

The invention will be described more in particular with reference to the accompanying drawing.

Fig. 1 shows in cross section an embodiment of the device according to the invention.

Fig. 2 illustrates the mode of operation of the device of Fig. 1. · Fig. 3 shows a cross section of a second embodiment of the device according to the invention.

In Figs. 1 and 2 the outer part of a nozzle, for a rocket motor is designated 3. The closing device comprises the cup-shaped cap 1 which is provided along its periphery with, a plane surface 2 which is intended to abut against the edge of the mouth of the nozzle 3. Between the surface 2 on the cap 1 and the mouth of the nozzle is - ■ I inserted a sealing ring 8 which is made e.g. of lead.

At its periphery the cup 1 also has an internal annular p&rt 9 which extends into the nozzle 3 so that a and the inside of the nozzle. At the joint between part 9 and the plane surface 2 there is a circumferential groove 10 which has a U-shaped cross section.

The cap 1 is held fast to the nozzle 3 by an annular retaining member which comprises a part which is' attached, e.g. screwed to the cap 1 and a second part 5 which can be attached, e.g. screwed to the nozzle 3 at its outer side. The parts k and 5 are joined by means of a third part 6 which has a small thickness and is so positioned that there is a free space inside it when the closing device is mounted on the nozzle.

During the travel of the projectile through the barrel upon firing the cap 1 protects the rocket motor from being subjected to the very high pressure existing in the barrel. However, this pressure also acts upon the annular retaining member, and the weakest portion 6 is thereby caused to bend inwards toward the space 7 and to rupture. Hereby the mechanical connection between the cap 1 and the nozzle 3 is interrupted since the connection between part k and 5 of the retaining member is broken, e.g. at the joint between parts 6 and as shown in Fig. 2. As long as the projectile is still within the barrel the cap 1 will still be pressed against the nozzle by the pressure existing in the barrel. When the projectile has left the barrel, however, the cap .1 is separated from the nozzle since there is no longer any outer pressure which holds the cap against the nozzle.

The weakened part 6 of the retaining member which can be considered as a membrane, is joined under a substantially. joint between parts and 6 will form a fracture indication. 1 •Due to the pressure which arises in the barrel upon the firing the cap 1 will rapidly be pressed against the nozzle 3 with a great force. Hereby the sealing ring 8 will be compressed and particles of the sealing material will be thrown inwards towards the part 9 of the cap 1. These particles are trapped by the groove 10 and thereby prevented from being thrown into the rocket motor.

In the modification shown in Fig. 3 the parts of ■the retaining member are designated 11+,15 and 16. The weakened part or membrane 16 is here in the form of an annulus located in a plane at right angles to the longitudinal axis of the nozzle. The cap 1 is here provided with a shoulder 11 which has a sharp edge situated at the joint between parts Ih and 16 of the retaining member. During the travel of the projectile through the barrel the part 16 will be sheared off by this edge.

Other modifications are possible within the scope of the invention.

Claims (8)

1. What is claimed is: 1.
2. A closing device for the nozzle of a projectile furnished with a rocket motor and intended to be fired by means of a barrel and an outer drive charge, characterized in that it comprises a cap (1) of a material with a high tensile strength the periphery of which has a part (2) for making a tight contact with the edge of the mouth t of the nozzle (3) and an annular retaining member (M-,5,6) v! which has a first part ( ) which is attached to the cap (1), a second part (5) to be attached to the nozzle (3) : at its outer side and, a third part (6) joining said first (k) and second parts and having a relatively small thickness and being arranged so that a free space (7) is present inside said third part (6) when mounted on the nozzle, whereby this part under the influence of a suffi- , ciently high outer pressure can be bent inwards and break , so that the mechanical connection between the cap (1) and .1 the nozzle (3) is interrupted. <~ 2.
3. A device as claimed in claim 1, characterized in that the cap (1) is cup-shaped with a concave side facing the mouth of the nozzle (3). 3· A device as claimed in claim 1 or 2, characterized in that the cap (1) is made of steel and that the retaining member is made of a light metal. . .
4. A device as claimed in any of the preceding claims, characterized in that said first part (h) of the retaining member has a plane surface situated, in a plane at ■· right angles to the longitudinal axis of the nozzle (3) ,
5. 5. A device as claimed in any of claims 1-3» characterized in that said third part (16 in Fig. 3) forms an annulus situated in a plane at right angles to the longitudinal axis of the nozzle (3).
6. 6. A device as claimed in claim 5, characterized in that the cap (1) is provided with a shoulder (11) along its periphery, said shoulder having a sharp edge situated at the joint between said first (l^) and third (16) parts of the retaining members.
7. 7. A device as claimed in any;of the preceding claims, characterized in that -a sealing ring (8) is inserted. < between the cap (1) and the nozzle (3). . i
8. 8. A device as claimed in claim 1, characterized in that the cap (1) has an annular part (9) extending into the nozzle (3) when the cap is mounted on the nozzle, a certain play being present between the outside of the annular part (9) and the inside of the nozzle (3), and ·'·> that a circumferential U-shaped groove (10) is provided -at the joint between the annular part (9) and the part (2) intended for contact