Patent Application
20150247713
This application claims the priority, under 35 U.S.C. ยง119, of German application DE 10 2013 010 256.1, filed Jun. 18, 2013; the prior application is herewith incorporated by reference in its entirety.
The invention relates to a method for sealing a projectile having a wall against propellant charge gas pressure occurring during firing of the projectile, wherein a propellant charge is ignited and the projectile is acted upon from the outside with the propellant charge gas pressure.
Modern, large-caliber ammunition is frequently equipped with a projectile which has control elements, control electronics and optionally a seeker head with an optical sensor. By an electronic homing system, it is possible for a shooter to record an image of a target object and to transmit the associated image data via a data line to the control electronics of the projectile before the projectile is fired. For this purpose, control data have to be transferred from the shooter's homing system to the control electronics of the projectile.
Since the control electronics are located in the interior of the projectile, whereas the shooter's homing system is located outside the projectile, an electrical interface permitting an electrical connection between the control electronics and the homing system through a wall of the projectile is required. The electrical interface is expediently located in a channel in the wall of the projectile.
During firing of the projectile, hot propellant charge gas with a gas pressure of several 1000 bar, with which the projectile is acted upon from the outside and is accelerated in the barrel or tube, arises. Penetration of the hot propellant charge gas into the interior of the projectile results in the control electronics located therein being damaged, and therefore flight control of the projectile by the control electronics may thereby be rendered inoperative. The electrical interface therefore has to be sealed so as to be tight in respect of the propellant charge gas pressure.
Such an electrical interface is known from German patent DE 10 2005 029 325 B4, corresponding to U.S. Pat. No. 7,491,099. The electrical interface is sealed by a metal pressed body which is pressed into the wall so as to be tight in respect of the propellant charge gas pressure, and in which a metal contact pin is arranged. An electrical insulating layer which electrically insulates the wall from the pressed body is applied to the wall or to the pressed body. In order to seal against extreme propellant charge gas pressures which arise during firing of the projectile, the pressed body has to be firmly pressed in and has to sit very tightly and the insulating layer has to be thin.
It is an object of the present invention to specify a method with which a projectile can be reliably sealed against penetration of propellant charge gas from the outside into the interior thereof.
This object is achieved by a method of the type referred to at the beginning, in which, according to the invention, a pressure unit of an electrical interface arranged in a channel in the wall is moved in the channel by the propellant charge gas pressure and presses a seal into a sealing seat.
The invention is based on the consideration that an electrical insulating layer which, in the prior art, is located on a wall or on a pressed body may be damaged if the pressed body tilts during assembly when being pressed into the wall. Damage to the electrical insulating layer may render the electrical interface unusable if electrical contact between the wall and the contact connection arises because of the damage.
An insulating layer which is easy to damage can be omitted if an electrically insulating pressed body is used. However, the latter has to be highly stable because of the extreme propellant charge gas pressures and temperatures during firing of the projectile, and therefore only ceramic or glass are suitable as materials. However, tests have shown that a pressed body made of glass or ceramic may crack during firing because of the extreme propellant charge gas pressures of modern projectiles, thus impairing the tightness of the electrical interface.
The invention solves these problems by the pressure unit being arranged movably in the channel. As a result, the pressure unit can press the seal into the sealing seat by the propellant charge gas pressure. The propellant charge gas pressure is therefore used for sealing the channel itself. This gives rise to the advantage that the channel does not have to be so tightly sealed before the firing. A pressed body can be omitted. Instead, the interface can be inserted considerably more loosely into the channel during assembly. This significantly reduces the risk of damage to electrical insulation.
The channel is a passage in the wall of the projectile, which, together with a contact connection, produces an electrical contact through the wall. In a preferred manner, the channel is cylindrically symmetric. The axis of symmetry of the channel should be understood here as the axis of the channel.
A contact connection is an electrical connecting element which is provided in order to produce an electrical connection between control electronics located in the projectile and an electrical system arranged outside the projectile. The contact connection can have a plug-in connection for the plugging in of a plug.
The channel can have a tapered portion on which the seal can be supported in particular in a flat manner. The sealing seat can be formed by such a supporting surface. Further configurations of the channel can have a plurality of tapered portions and a plurality of sealing seats which can each comprise a supporting surface formed by the tapered portion thereof.
A displacement of the pressure unit relative to the wall is interpreted as the movement of the pressure unit under the action of propellant charge gas pressure. The movement advantageously takes place parallel to the axis of the channel. In a preferred manner, the movement comprises a distance of at least 0.05 mm, in particular at least 0.1 mm.
In an advantageous embodiment of the invention, the pressure unit is a contact connection of the electrical interface. By this means, the interface can be of particularly compactly sized design.
Furthermore, it is advantageous if, when the propellant charge gas pressure occurs, the pressure unit presses a sealing section, which is oriented perpendicular to the axis of the channel, parallel to the axis of the channel into the sealing seat. A particularly large pressure on the sealing seat and therefore good sealing can thereby be achieved. In general, the seal can have one or more sealing sections, wherein a sealing section can be oriented perpendicular, parallel or obliquely to the axis of the channel.
Furthermore, it is advantageous if the seal has a sealing section oriented parallel to the axis of the channel. The sealing section expediently surrounds the pressure unit, in particular the contact connection, radially. During the movement of the pressure unit, the sealing section can be pressed into the channel, for example by a pressure element of the pressure unit, expediently such that the sealing section is pressed in radially between the pressure unit and the wall and therefore seals the channel against penetration by propellant charge gas.
As already explained, the pressure unit or the contact connection can be inserted loosely in the channel such that damage to the seal during insertion thereof is avoided. However, the contact connection here should be held so firmly in the channel that it does not fall out of the channel even in the event of shaking movements of the projectile, for example during transport. In addition, it is advantageous if the interface is sealed by the contact connection and the seal so as to be weather tight.
It is therefore advantageous if the pressure unit is inserted only in a roughly pressed manner with the seal into the channel. This permits the movement of the pressure unit in the channel when the propellant charge gas pressure occurs, the movement bringing about a particularly tight pressing of the seal into the sealing seat. On being pressed in by the pressure unit, the seal is advantageously pressed into the channel more strongly radially than during the rough pressing, and this brings about reliable sealing of the channel against penetration by propellant charge gas.
The seal advantageously has a sealing section oriented perpendicularly and a sealing section oriented parallel to the axis of the channel. It is advantageous if the compressive force caused on a sealing section, which is oriented perpendicular to the axis of the channel, by the movement of the contact connection is greater, in particular is at least 30 times greater, than the frictional force, which is caused during the movement of the contact connection, along a sealing section oriented parallel to the axis of the channel. As a result, firm pressing in of the seal during the movement of the contact connection is made possible. The perpendicular sealing section is expediently arranged further on the inside than the parallel sealing section.
In a further advantageous embodiment of the invention, when the propellant charge gas pressure occurs, the pressure unit presses in a first sealing section, in particular a sealing section which is arranged further on the inside and is oriented perpendicular to the axis of the channel, temporally before a second sealing section which, in particular, is a sealing section which is arranged further on the outside and is oriented parallel to the axis of the channel.
Two sealing sections can be pressed in temporally one after the other if there is a gap between the pressure unit and a sealing section. The pressure element thus, for example, only exerts a pressure on a sealing section oriented parallel to the axis of the channel if a sealing section oriented perpendicular to the axis of the channel has been compressed sufficiently strongly beforehand.
The invention also relates to ammunition having a propellant charge and a projectile. The projectile has a wall which separates an interior space of the projectile from an exterior space around the projectile, and an electrical interface which is provided with a seal and is arranged in a channel in the wall.
Reliable sealing of the interior space of the projectile can be achieved if, according to the invention, a pressure unit is mounted in the channel so as to be movable relative to the wall in such a manner that said pressure unit, during the movement thereof caused by propellant charge gas pressure arising during firing of the projectile, presses the seal against the wall. The pressure unit is expediently a contact connection. The pressure unit or the contact connection can be surrounded by the seal.
In an advantageous refinement of the invention, the seal has a cup shape. The pressure element is advantageously arranged in the cup of the seal.
Furthermore, it is advantageous if the seal has a sealing section which is arranged further on the inside and is oriented perpendicular to the axis of the channel, and a sealing section which is arranged further on the outside and is oriented parallel to the axis of the channel.
In order to produce the interface, the seal is advantageously first of all placed onto the pressure unit, in particular pressed onto the latter. Alternatively, the seal can be sprayed onto the pressure unit, for example by thermal spraying, and then the pressure unit and the seal are inserted into the channel. It is advantageous if the pressure unit is inserted in a roughly pressed manner with the seal into the wall of the projectile. The effect which can be achieved by this is that the pressure unit together with the seal remains securely arranged in the channel during transport of the projectile. In addition, sealing against moisture, for example during storage of the ammunition, can thereby be achieved.
The arrangement of the pressure unit and the seal in the channel is expediently mounted movable such that, during firing of the projectile, a movement of the contact connection that is caused by the propellant charge gas pressure and in which the seal is pressed against the wall is possible.
The seal advantageously has a plurality of sealing sections which, in a particularly advantageous refinement of the invention, have one dedicated contact surface with the wall per sealing section. This has the advantage that a better sealing effect can be achieved. The sealing sections can comprise a sealing section which is arranged further on the inside and is oriented perpendicular to the axis of the channel, and a sealing section which is arranged further on the outside and is oriented parallel to the axis of the channel. In an alternative advantageous refinement of the invention, the seal has a sealing section which is arranged further on the inside and is oriented parallel to the axis of the channel, and a sealing section on the outside, which sealing section is arranged further on the outside and is oriented perpendicular to the axis of the channel.
At least one sealing section is expediently in the form of a hollow cylinder. On the inside of the wall of the projectile, said hollow cylinder can have a base with an, in particular, circular opening, through which a contact connection can be guided. In an expedient manner, the casing of the hollow cylinder forms a sealing section which is arranged further on the outside and is oriented parallel to the axis of the channel, and the base of the hollow cylinder can form a sealing section which is arranged further on the inside and is oriented perpendicular to the axis of the channel.
A good sealing action of the seal in the channel can be achieved if a sealing section which is oriented parallel to the axis of the channel is pressed inward parallel to the axis during firing and, in the process, exerts a radial pressure on the wall. A radial pressure contributing to the sealing can be achieved if the height of the sealing section oriented parallel to the axis of the channel is at maximum 20 times, in particular at maximum 8 times, the thickness of the sealing section. A firm radial pressing in of the sealing section, which is oriented parallel to the axis of the channel, between the contact connection and the wall can take place. For as firm a radial compression as possible, it is furthermore advantageous if the thickness of the sealing section oriented parallel to the axis of the channel is at least 0.1 mm, in particular at least 0.3 mm.
The pressure unit is advantageously provided with a thickened portion, the maximum thickness of which is expediently greater than the minimum thickness of a tapered portion of the channel, which tapered portion forms a sealing seat.
In a further advantageous refinement of the invention, a sealing section oriented parallel to the axis of the channel radially surrounds a cylindrical thickened portion of the pressure unit. With regard to a good sealing action, the thickness of the sealing section oriented parallel to the axis of the channel is at least 10%, in particular at least 15%, of the thickness of the thickened portion.
The tapered portion of the channel can be continuous or step-shaped. A step-shaped tapered portion is advantageous. The thickened portion can have, for example, a cylindrical shape or the shape of a conical section. The pressure unit preferably has a thickened portion with a shoulder by which a sealing section oriented perpendicular to the axis of the channel can be pressed against the sealing seat.
In an advantageous refinement of the invention, the pressure unit has a pressure element. The pressure element can bring about a pressing in of a sealing section between the pressure unit and the wall during the movement of the pressure unit. In the case of a seal having a plurality of sealing sections, the sealing section which can be pressed in by the pressure element can be a sealing section which is arranged further on the outside. If the sealing section arranged further on the outside is oriented parallel to the axis of the channel, the sealing section can advantageously be pressed in radially by the pressure element between the contact connection and the wall.
In an expedient manner, the pressure element is spaced apart radially from the wall by a gap, and therefore the pressure unit is electrically insulated from the wall.
In addition, it is advantageous if the pressure unit has a pressure element which is spaced apart from the sealing section of the seal by a gap. The gap makes it possible for the sealing section to be pressed in before another sealing section such that a sealing action can be achieved in two part steps. The gap is expediently arranged between the pressure element and a sealing section which is arranged further on the outside and is oriented parallel to the axis of the channel. The sealing section can thereby be pressed in after a sealing section which is arranged further on the inside and in particular is oriented perpendicular to the axis of the channel.
The seal preferably contains dielectric material. An additional electrical insulating layer on the seal or the wall of the projectile, the insulating layer insulating the pressure unit, and in particular the contact connection, electrically from the wall of the projectile, can be omitted. A seal composed of an electrically insulating plastic which may optionally be fiber-reinforced is particularly advantageous.
Furthermore, the invention relates to ammunition having a propellant charge and a projectile having a wall and an electrical interface, which is arranged in a channel in the wall, with a contact connection and a seal which has a sealing section which is oriented parallel to the axis of the channel, surrounds the contact connection radially and seals the contact connection with respect to the wall.
A reliable sealing of the interior space of the projectile can be achieved by the fact that, according to the invention, the contact connection has at least one pressure element which at least partially radially overlaps the sealing section oriented parallel to the axis of the channel.
If the seal has a plurality of sealing sections, the sealing section which is oriented parallel can be arranged further on the outside or further on the inside in the channel. The seal is advantageously of cup-shape design, and in particular is in the form of a hollow cylinder.
The contact connection should expediently be held loosely in the channel such that the contact connection can be pressed in when compressive forces resulting from propellant charge gas pressure arising during firing of the projectile act on the contact connection. This has the advantage that the seal, for its part, can be pressed in through the contact connection.
The description provided up to now of advantageous refinements of the invention contains numerous features which are reproduced, partially combined into a plurality of features, in the individual dependent claims. However, these features can expediently also be considered individually and put together to form meaningful further combinations. In particular, these features can in each case be combined individually and in any suitable combination with the method according to the invention and the device according to the invention as per the independent claims.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a method for sealing a projectile and ammunition containing the projectile, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
Referring now to the figures of the drawings in detail and first, particularly to
The projectile 6 has a wall 10 which separates an interior space of the projectile 6 from an exterior space around the projectile 6. Control electronics 12 are located in the interior space of the projectile 6. The projectile 6 is surrounded from the outside by the propellant charge 4.
An electrical interface 16 is arranged in a channel 14 in the wall 10 of the projectile 6. A data line 18 connects the control electronics 12 located in the projectile 6 to an electrical system 20 arranged outside the ammunition 2.
The contact connection 22 reaches completely through the channel 14 and is surrounded by a seal 24. The contact connection 22 has a pressure element 30 and a cylindrical thickened portion 32 with a shoulder 34. The seal 24 is in the form of a hollow cylinder. The latter is oriented parallel to an axis 36 of the channel 14 and, on the inside of the wall 10, has a base with a cylindrical opening through which the contact connection 22 is guided. The casing of the hollow cylinder forms a sealing section 38 which is arranged further on the outside and is oriented parallel to the axis 36 of the channel 14. The base forms a sealing section 40 which is arranged further on the inside and is oriented perpendicular to the axis 36 of the channel 14.
The sealing section 38 which is oriented parallel to the axis 36 of the channel 14 radially surrounds the thickened portion 32 of the contact connection 22 and is located in a radial part of the sealing seat 28. The sealing section 40 which is oriented perpendicular to the axis 36 of the channel 14 rests on the axial part of the sealing seat 28. A gap 42 spaces the pressure element 30 apart from the sealing section 38 which is oriented parallel to the axis 36 of the channel 14. A further gap 44 spaces the pressure element 30 of the contact connection 22 apart radially from the wall 10.
The thickened portion 32 of the contact connection 22 has a diameter of 3 mm. The channel 14 has a diameter of 4 mm. The sealing section 38 which is oriented parallel to the axis 36 of the channel 14 and the sealing section 40 which is oriented perpendicular to the axis 36 of the channel 14 have a thickness of 0.5 mm. The sealing section 38 which is oriented parallel to the axis 36 of the channel 14 has a height of 3 mm.
To produce the interface 16, the cup-shaped seal 24 is placed around the contact connection 22, in particular is pressed on the thickened portion 32 of the contact connection, such that the seal 24 radially compresses the contact connection 22. The contact connection 22 is subsequently inserted with the seal 24 into the channel 14, specifically in such a manner that the contact connection 22 is not ejected from the channel 14 even in the event of strong shaking. The seal 24 seals the channel 14 so as to be tight with respect to rain, and therefore the interior components of the projectile 6 are protected against weathering effects. In the event of a pressure from the outside of above 100 bar, the contact connection, which is located relatively loosely in the channel 14, is moved inwards such that the contact connection presses onto the inner sealing section 40.
During firing of the projectile 6, the propellant charge 4 of the ammunition 2 is ignited. The propellant charge gas arising in the process presses from the outside against the projectile 6 with a gas pressure of approximately 6000 bar. The pressure causes the holding device 8 to break off and leads to acceleration of the projectile 6 along a barrel. The propellant charge gas pressure in particular also acts on the contact connection 22 of the electrical interface 16.
The movably mounted contact connection 22 first of all presses, with the shoulder 34 of the thickened portion 32 thereof, during the movement thereof caused by the propellant charge gas pressure, the sealing section 40, which is oriented perpendicular to the axis 36 of the channel 14, into the sealing seat 28. A first sealing action is thereby achieved. Owing to the gap 42 between the pressure element 30 and the sealing section 38 oriented parallel to the axis 36 of the channel 14, the contact connection 22 initially does not yet press against the sealing section 38 which is oriented parallel to the axis 36 of the channel 14. By this means, the inner sealing section 40 is initially compressed with the greatest possible pressure, and therefore the sealing section seals cracks possibly arising in the channel 14 during firing.
If the sealing section 40 which is oriented perpendicular to the axis 36 of the channel 14 is pressed in to such an extent that the pressure element 30 of the contact connection 22 touches the sealing section 38 which is oriented parallel to the axis 36 of the channel 14, the pressure element 30 begins to exert a pressure on the sealing section 38. The sealing section 38 is pressed inwards and therefore causes a radial compressive force against the contact connection 22 and the wall 10. An additional sealing action is thereby achieved by the gap between the thickened portion 32 of the contact connection 22 and the channel wall then also being sealed by the radial pressure of the sealing section 38. The channel 14 is reliably sealed and the control electronics 12 of the projectile 6 protected.
The channel 14 has a tapered portion 26 with two steps, of which one forms an axial sealing seat 46 located further on the outside and the other forms a radial sealing seat 48 located further on the inside. The seal 24 does not have a base on the inside of the wall 10 of the projectile 6, but rather has, on the outer side of the wall 10 of the projectile 6, a collar which protrudes radially over the casing of the hollow cylinder section of the seal 24 and inwardly has a circular opening through which the contact connection 22 is guided.
The casing of the hollow cylinder again forms the sealing section 38 which is oriented parallel to the axis 36 of the channel 14, but is arranged further on the inside of this exemplary embodiment. In this case, the cover forms the sealing section 40 which is oriented perpendicular to the axis 36 of the channel 14, but is arranged further on the outside in this exemplary embodiment. The sealing section 40 which is oriented perpendicular to the axis 36 of the channel 14 rests on the sealing seat 46 which is arranged further on the outside. The pressure element 30 of the contact connection 22 rests on the sealing section 40 which is oriented perpendicular to the axis 36 of the channel 14.
Also in the case of the electrical interface 16 illustrated in
If the sealing section 40 which is oriented perpendicular to the axis 36 of the channel 14 is pressed into the sealing seat 46 arranged further on the outside to such an extent that the sealing section 38 which is oriented parallel to the axis 36 of the channel 14 touches the sealing seat 48 arranged further on the inside, the contact connection 22 begins to radially press in the sealing section 38, which is oriented parallel to the axis 36 of the channel 14, between the contact connection 22 and the wall 10.
The seal 24 partially surrounds the thickened portion 32 of the contact connection 22. The seal 24 is in the form of a cylinder. The cylinder is oriented parallel to the axis 36 of the channel 14 and has a cutout along the axis 36 of the channel 14, through which the contact connection 22 is guided. The cutout has a cylindrical section arranged further on the outside and a frustoconical section which adjoins the cylindrical section and is arranged further on the inside. The two sections of the cutout divide the seal 24 into a sealing section 58 which is arranged further on the outside and surrounds the cylindrical section of the thickened portion 32 and a sealing section 60 which is arranged further on the inside and surrounds the frustoconical section of the thickened portion 32.
The contact connection 22, during the movement thereof caused by the propellant charge gas pressure, presses the sealing section, which is arranged further on the inside, by the thickened portion 32 radially against the wall 10 and axially against the tapered portion 26 such that the compressive force exerted on the inner sealing section by the contact connection 22 therefore has both a directional component which is perpendicular to the axis 36 of the channel 14 and a directional component which is parallel to the first directional component. Reliable sealing of the electrical interface 16 is thereby achieved.
The following is a summary list of reference numerals and the corresponding structure used in the above description of the invention:
| Number | Date | Country | Kind |
|---|---|---|---|
| 102013010256.1 | Jun 2013 | DE | national |
