US20070028756A1

US20070028756A1 - Seal, in particular for caseless ammunition

Info

Publication number: US20070028756A1
Application number: US11/395,122
Authority: US
Inventors: Helmut Konicke
Original assignee: Diehl BGT Defence GmbH and Co KG
Current assignee: Diehl BGT Defence GmbH and Co KG
Priority date: 2005-05-03
Filing date: 2006-03-31
Publication date: 2007-02-08
Also published as: DE102005020669A1; ZA200603444B; EP1719966A1

Abstract

A seal (10) which seals a gap (12) which is provided between a stationary first element (14), and a moving second element (16), in particular for caseless ammunition, with the second element (16) having a cylindrical sealing ring seat (22) in which a sealing ring (24) is provided. The sealing ring seat (22) has a main section (26) and secondary section (28) with a reduced diameter. The sealing ring (24) has a main body (30) and an initial seal (32). The sealing ring seat main body (26) has an internal diameter (34) which is larger than the external diameter (36) of the sealing ring main body (30) by at least an amount to compensate for thermal expansion. The sealing ring initial seal (32) is forced against the cylindrical sealing ring seat secondary section (28) with a push fit to produce a seal.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
The invention relates to a seal for sealing the gap between a stationary, rigid first element, such as a weapon barrel or the like, and thereto adjacent a moving second element, such as a cartridge chamber or the like, particularly for caseless ammunition.
The stationary, rigid first element is, for example, a breech face of the weapon barrel, a second part of a multiple part cartridge chamber, or the like. The moving second element is, for example, a cartridge chamber such as the revolving drum of a revolving-drum weapon, a lateral slide or the like.
2. Discussion of the Prior Art
In the case of revolving-drum weapons, it is known for the gap between the moving second element, which is in the form of a drum which can rotate, and the stationary, rigid first element which is adjacent to it and is in the form of a rigid weapon barrel to be sealed by means of an axially moving sealing ring. By way of example, the sealing ring is composed of steel.
In the case of revolving-drum weapons such as these, the gas pressure builds up in the cartridge case. The powder gas is in this case enclosed by the cartridge case and, on the accelerated projectile, by the guide band which cuts into it. After a short movement of the projectile, a small proportion of the highly compressed powder gas is passed suddenly to the sealing ring, passing by the projectile and being directed through channels. Even before the projectile and the main mass of gas pass the separation point between the revolving drum and the weapon barrel, that is to say the gap between these components, the steel sealing ring obturates and seals the gap.
In cartridge chambers for caseless ammunition with at least one separation point, that is to say at least one gap, for example between the cartridge chamber and the weapon breech face, the gas pressure builds up only with the detonation. The sealing ring must in this case provide a seal against the very high-speed detonation gases, which are rich in particles, and against the rising powder gas pressure even in the shot development phase, because there is no directed, suddenly occurring powder gas—as in the case of cased ammunition—with caseless ammunition.
Thus, with caseless ammunition, the sealing ring has to carry out two obturation functions in the so-called resting powder gas; it must bridge the gap between the stationary, rigid first element and the moving second element both in the radial direction and in the axial direction, and must make contact to form a gas-tight seal.
A moving sealing ring as has already been mentioned above cannot, however, provide a seal sufficiently quickly during the gas development phase with caseless ammunition so that it is possible for so-called “box fire” to occur. In order to avoid such “box fire”, extremely accurately ground steel sealing rings have been proposed, although these lose their original movement play as a result of thermal expansion, so that their effectiveness is lost.
However, nevertheless, the highly compressed detonation gas moves the sealing ring beyond a specific gas pressure level, so that a friction weld, that is to say “fretting” can occur between the cylindrical external circumferential surface of the sealing ring and the cylindrical cartridge chamber sealing ring seat and, in consequence, this can lead to complete loss of function.

SUMMARY OF THE INVENTION

The invention is therefore based on the object of providing a seal of the type mentioned initially, by means of which it is possible to reliably avoid the defects described above, particularly with caseless ammunition, in a physically simple manner.
In the case of the seal according to the invention, the diameter of the cylindrical sealing ring seat main section is designed to be larger by a defined amount than the external diameter of the cylindrical sealing ring main body, so that the sealing ring, which expands faster as a result of thermal expansion than the moving second element, provides a form of thermal compensation with respect to the sealing ring main body, which is applied virtually, but not completely, until the diameter of the sealing-ring seat main section of the moving second element likewise matches the thermal expansion. In this way, a small annular residual gap always remains between the cylindrical outer surface of the sealing ring main body and the cylindrical sealing ring seat main section of the moving second element—such as a slide or revolving drum—on which there is no gas pressure load. This originally relatively large annular initial residual gap between the cylindrical outer surface of the sealing ring main body and the cylindrical inner surface of the sealing ring seat main section would, however, lead to undesirable leaking. In the case of the seal according to the invention, this leaking is overcome by the elastically resilient sealing ring initial seal which is provided in the cylindrical sealing ring seat secondary section, in that the sealing ring initial seal is forced against the sealing ring seat secondary section in an originally mechanically prestressed manner, to produce a seal. This can be achieved by the dimensions of the elastically resilient sealing ring initial seal being matched with a push fit to the cylindrical sealing ring seat secondary section.
The insertion forces which are produced by this push fit advantageously and additionally ensure that the sealing ring is mechanically firmly seated, to a limited extent, in the axial direction.
After the first application of pressure, that is to say the pressure load, the axial separating gap between the stationary, rigid first element and the sealing ring that is adjacent to it is cancelled out, that is to say the sealing ring assumes a stable contact position with respect to the stationary, rigid first element after the initial pressure load. When the subsequent, next gas pressure change occurs, there is not a large axial separating gap between the rigid first element and the sealing ring. This provides good axial initial sealing. Furthermore, sealing between the sealing ring and the moving second element is ensured between the sealing ring seat secondary section and the resilient sealing ring initial seal.
The major features of the sealing ring initial seat are its slim shape and resilient method of operation, that is to say operation without fatigue.
The two-part design of the integral sealing ring according to the invention is also significant, specifically the subdivision into a solid, virtually inelastic main body and a resilient sealing lip. This is intrinsically resilient in the radial direction, and is arranged effectively like a hinge on the main body.

BRIEF DESCRIPTION OF THE DRAWINGS

Further details, features and advantages will become evident from the following description of one exemplary embodiment of the seal according to the invention, which is illustrated in the single FIGURE of the drawing.

DETAILED DESCRIPTION OF THE INVENTION

The FIGURE shows part of a longitudinal section illustrating one embodiment of the seal 10 for the gap 12 between a stationary, rigid first element 14 and a moving second element 16, which is adjacent to it. The first element 14 forms, for example, a weapon breech face, a weapon barrel, a second part of a multiple part cartridge chamber or the like, and has an aperture hole 18. The aperture hole 18 is axially aligned with a powder/gas combustion chamber 20 in the second element 16. The second element 16 has a cylindrical sealing ring seat 22, in which a sealing ring 24 is provided.
The sealing ring seat 22 has a cylindrical sealing ring seat main section 26 and, at its front end facing away from the first element 14 (the breech face of the weapon), a cylindrical sealing ring seat secondary section 28.
The sealing ring 24 has a sealing ring main body 30 and, at its front end facing away from the first element 14, an initial seal 32.
The cylindrical sealing ring seat main section 26 has an internal diameter 34 which is larger than the external diameter 36 of the sealing ring main body 30 by at least an amount to compensate for thermal expansion. This results in an annular residual gap 38 remaining between the sealing ring seat main section 26 and the sealing ring main body 30. However, this residual gap 38 would lead to leaking. This leaking is prevented by an elastically resilient, contact-making sealing ring initial seal 32 which is forced against the cylindrical sealing ring seat secondary section 28 in a mechanically prestressed manner to produce a seal. The insertion forces additionally ensure that the sealing ring 24 has a predetermined rigid fit in the axial direction.
A caseless propellant charge, which is not shown, is detonated in the cartridge chamber for caseless ammunition, that is to say in the second element 16, specifically in the combustion chamber 20. The gas pressure in the combustion chamber 20 builds up only on detonation. Even in the shot development phase, the sealing ring 24 provides a seal against the very high-speed detonation gases, which are rich in particles, and against the rising powder gas pressure.

1. After the initial pressure load, the axial gap 12 between the sealing ring 24 and the rigid first element 14 is cancelled out; the sealing ring 24 then assumes a stable, sealing contact position with respect to the first element 14. When the next gas pressure change occurs, there is no large axial gap between the rigid first element 14 and the sealing ring 24, thus ensuring good axial initial sealing.
2. The linear movement of the sealing ring 24 corresponding to the gap 12 takes place with the push fit of the sealing ring seat secondary section 28 on the sealing ring initial seal 32 (sealing lip of the sealing ring) being overcome. During this process, the sealing lip slides in the secondary section 28, subject to radial prestressing.

Nevertheless, sealing against the eroding detonation gases is ensured, since the sealing lip provides a seal, as a result of the push-fit prestressing, even in the initial position when it is flush on the left. In addition, the push fit is reinforced by the gas pressure that acts radially on the internal circumference of the elastically resilient initial seal 32. The small mass of the sealing lip means that its radial “mobility”—that is to say its function—is retained over a surprisingly long time. No “fretting” of the sealing lip occurs.
The sealing ring seat 22 has a stepped cylindrical internal contour, and the sealing ring 24 has a stepped external contour which is matched to it. At its rear end facing the first element 14, the sealing ring main body 30 is formed integrally with the sealing ring collar 40, which has a sealing ring surface 42 at the rear end. The sealing ring 24 is formed with an internal contour 44 which tapers with a small coning angle 46 from the elastically resilient initial seal 32 to the rear-end sealing ring collar 40 of the sealing ring 24.
The initial seal 32 is in the form of an annular sealing lip, which rests with a push fit against the sealing ring seat secondary section 28.
The sealing ring 24 can also be used as a sealing element between two rigid elements, as in the case of a gas pressure meter. The sealing ring is located between a weapon barrel and a cartridge chamber, which are axially rigid with respect to one another.
The invention can be used for all automatic weapons for caseless ammunition in a caliber range from about 4.5 to 203 mm, or larger.

LIST OF REFERENCE NUMERALS

10 Seal (for 12)
12 Gap (between 14 and 16)
14 Rigid first element
16 Moving second element
18 Aperture hole (in 14)
20 Powder-gas combustion chamber (in 16)
22 Sealing ring seat (of 16 for 24)
24 Sealing ring (in 22)
26 Sealing ring seat main section (of 22 for 30)
28 Sealing ring seat secondary section (of 22 for 32)
30 Sealing ring main body (of 24)
32 Sealing ring initial seal (of 24)
34 Internal diameter (of 26)
36 External diameter (of 30)
38 Residual gap (between 34 and 36)
40 Sealing ring collar (of 24)
42 Sealing ring surface (of 40)
44 Internal contour (of 24)
46 Small coning angle (of 44)

Claims

1. A seal for sealing the gap (12) which is provided between a stationary, rigid first element (14), such as a weapon barrel and a moving second element (16), such as a cartridge chamber for caseless ammunition, with the second element (16) or the first element (14) selectively having a cylindrical sealing ring seat (22) in which a sealing ring (24) is provided, wherein the sealing ring seat (22) has a cylindrical sealing ring seat main section (26) and, at a front end thereof facing away from the first element (14), a cylindrical sealing ring seat secondary section (28) with a reduced diameter, and in that the sealing ring (24) has a sealing ring main body (30) and an initial seal (32), which is provided at its front end facing away from the first element (14), with the sealing ring seat main section (26) having an internal diameter (34) which is larger than the external diameter (36) of the sealing ring main body (30) by at least an amount to compensate for thermal expansion, and with the sealing ring initial seal (32) being forced against the sealing ring seat secondary section (28) in a mechanically prestressed manner to produce a seal.

2. A seal according to claim 1, wherein the sealing ring seat (22) has a stepped internal contour and the sealing ring (24) has an external contour which is stepped in a manner matched thereto, the sealing ring main body (30) being provided, at a rear end thereof facing the first element (14), with a sealing ring collar (40) which has a sealing ring surface (42) on the rear end.

3. A seal according to claim 2, wherein the sealing ring (24) has an internal contour (44) which tapers with a small coning angle (46) from the sealing ring initial seal (32) to the sealing ring collar (40) at the rear end.

4. A seal according to claim 1, wherein the sealing ring initial seal (32) is in the form of an annular sealing lip.

5. A seal according to claim 1, wherein the sealing ring initial seal (32) is supported with a push fit against the sealing ring seat secondary section (28).

6. A seal according to claim 1, wherein said sealing ring (24) has the dimension ratios of the sealing lip (32) and sealing ring main body (30) in the range of 1:30 or more.