US3620123A

US3620123A - Closing device for the nozzle of a projectile furnished with a rocket-motor

Info

Publication number: US3620123A
Application number: US29119A
Authority: US
Inventors: Per-Olof Davidsson; Karl Goesta Hoegberg
Original assignee: Bofors AB
Current assignee: Saab Bofors AB
Priority date: 1969-04-23
Filing date: 1970-04-16
Publication date: 1971-11-16
Anticipated expiration: 1988-11-16
Also published as: IL34337A; JPS4928399B1; FR2046373A5; DE2019244A1; NL7005813A; IL34337A0; NO122870B; GB1244299A; BE749412A; SE331435B

Abstract

A CAP FOR CLOSING THE NOZZLE OF THE ROCKET ENGINE IN A ROCKET-PROPELLED PROJECTILE WHICH IS TO BE LAUNCHED BY MEANS OF A BARREL AND AN EXTERNAL DRIVE CHARGE. THE CAP HAS A MAIN PORTION FOR MAKING A SEALING CONTACT WITH THE EDGE OF THE NOZZLE, A THREADED PORTION SCREWED ONTO THE OUTSIDE OF THE NOZZLE, AND A WEEKENED CIRCUMFERENTIAL PORTION BETWEEN THE MAIN PORTION AND THE THREADED PORTION. DURING THE TRAVEL OF THE PROJECTILE THROUGH THE BARREL THE WEAKENED PORTION IS RUPTURED BY THE PRESSURE EXERTED BY THE COMBUSTION GASES PRODUCED BY THE DRIVE CHARGE WHEREBY THE HOLDING CONNECTION BETWEEN THE NOZZLE AND THE MAIN PORTION OF THE CAP IS SEVERED.

Description

ON 3,620,,l23

OF A PROJECLILU ROCKET-MOTOR 16, 197

ETAL

NOZZLE Nov. 16, 1971 PER'OLOF DAVIDSS CLOSING DEVICE FOR THE FURNISHED WITH Filed April PER- 01.

JNVHNIURS DA v/Q sso/v KAlfwGOsrA HOGBERG Arrow/5Y5 United States Patent Office 3,620,123 Patented Nov. 16, 1971 U.S. Cl. 891.8 8 Claims ABSTRACT OF THE DISCLOSURE A cap for closing the nozzle of the rocket engine in a rocket-propelled projectile which is to be launched by means of a barrel and an external drive charge. The cap has a main portion for making a sealing contact with the edge of the nozzle, a threaded portion screwed onto the outside of the nozzle, and a weakened circumferential portion between the main portion and the threaded portion. During the travel of the projectile through the barrel the weakened portion is ruptured by the pressure exerted bythe combustion gases produced by the drive charge whereby the holding connection between the nozzle and the main portion of the cap is severed.

BACKGROUND OF THE INVENTION 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.

SUMMARY OF THE INVENTION 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 realtively small thickness and being so arranged that when the closing device is mounted on the nozzle a free space is present inside said third part, whereby this part under the action of a sufiiciently 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 metal. In order to increase the resisting power of the cap against the pressure in the barrel the cap is preferably cup-shaped and has e.g. the

form of a semisphere with the concave side facing the mouth of the nozzle.

DRAWINGS AND DETAILED DESCRIPTION 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 inserted a sealing ring 8 which is made e.g. of lead.

At its periphery the cup 1 also has an internal annular part 9 which extends into the nozzle 3 so that a small play is present between the outer side of part 9 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 4 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

4 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

4 and 5 of the retaining member is broken, e.g. at the joint between parts 6 and 4- 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 right angle to the plane surface of part 4, whereby the joint between

parts

4 and 6 will form a fracture indication.

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 14, 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

14 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.

What is claimed is:

11. 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, comprising a cap (ll) 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 of the nozzle (3) and an annular retaining member (4, 5, 6) which has a first part (4) 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 (4) 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 sufficiently high outer pressure can be bent inwards and break so that the mechanical connection between the cap (1) and the nozzle (3) is interrupted.

2. A device as claimed in claim 1, in which the cap (1) is cup-shaped with a concave side facing the mouth of the nozzle (6).

3. A device as claimed in claim 1, in which the cap (1) is made of steel and the retaining member (4, 5, 6) is made of a light metal.

4. A device as claimed in claim 1, in which said first part (4) of the retaining member has a plane surface situated in a plane at right angles to the longitudinal axis of the nozzle (3), and said third part (6) of the retaining member joins said first part (4) at said surface under right angles.

5. A device as claimed in claim 1, in which 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. A device as claimed in claim 5, in which 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 (14) and third (16) parts of the retaining members.

7. A device as claimed in claim 1, in which a sealing ring (8) is inserted between the cap (1) and the nozzle (3). p

8. A device as claimed in claim 1, in which 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 a circumferential U-shaped groove (510) is provided at the joint between the annular part (9) and the part (2,) intended for contact with the mouth of the nozzle.

References Cited UNITED STATES PATENTS 2,421,522 6/1947 Pope 89-l.818 2,644,364 7/1953 Nass 891.818 2,788,744 4/1957 Donner 10293 3,139,794 7/1964 Barnes, Jr. et a1. 891.8 18

SAMUEL W. ENGLE, Primary Examiner US. 01. X.R.