Temperature compensation system for barrels

Abstract

The invention relates to a barrel (10) for launching device (1), whereas the barrel (10) is arranged with a bore (20) for the launching of projectiles (100) with a propellant charge (110), whereas the barrel (10) is arranged with at least one cavity (12, 14, 16), whereas a substance for storing thermal energy is arranged in said at least one cavity (12, 14, 16). The invention further consists of an ejection device and a method for storing thermal energy in a barrel.

Description

TEMPERATURE COMPENSATION SYSTEM FOR BARRELSTECHNICAL FIELD

[0001] The present invention relates to a barrel for a launch device, where the barrel is arranged with a barrel for launching projectiles with a propellant charge. The invention further consists of an ejection device and a method for storing thermal energy in a barrel.BACKGROUND OF THE INVENTION, PROBLEM AREA AND KNOWN TECHNOLOGY

[0002] Conventional barrel-based weapon systems are arranged with at least one barrel out of which a projectile is propelled, shot, by a propellant charge. Barrels can be smooth-drilled or arranged with knurling, which means that the projectile is rotated during the firing process. Barrels are preferably made of metal, but can also be made of a ceramic, and are designed with a circularly symmetrical crosssection machined into the barrel. During the firing process, heat is generated when the movement of the projectile in the barrel is caused by a gas pressure that is generated by the gunpowder, propellant, being burned. Preferably, the gunpowder is burned so that the pressure generated on the projectile is constant during the movement of the projectile in the barrel. The combustion of the propellant and the friction of the projectile against the wall of the barrel result in the barrel being heated up. If additional projectiles are fired before the barrel has cooled down to its original temperature, additional thermal energy will be added to the barrel, which is why cooling of the barrel becomes even more important for barrels intended to fire several projectiles within a short time interval.

[0003] Problems related to barrels include, for example, accidental ignition of propellant intended for subsequent projectiles, also referred to as "cook off" or "cooking off". Furthermore, different temperatures on the barrel can affect the combustion of the propellant which can cause a change in the velocity of the iprojectile upon launch, also referred to as VO. For this reason, regulation and control of the temperatures of the barrel improves the performance of the launch system.

[0004] Various forms of cooling methods, including cooling fins and / or circulating coolant, are well known in the technical field. Different systems for storing, storing, thermal energy in or near the barrel other than in the breech of the barrel are not known.

[0005] A solution to the problem above and additional problems along with solutions are described below.THE INVENTION AND ITS PURPOSE

[0006] One purpose of the present invention is to solve the problems identified above.

[0007] An additional purpose of the present invention is a barrel for a launching device, whereas the barrel is arranged with a bore for launching projectiles with a propellant charge, characterized in that the firing tube is arranged with at least one cavity, in addition to the bore of the firing tube, whereas a substance for storing thermal energy is arranged inside said at least one cavity.

[0008] According to additional aspects of a barrel according to the invention, the following applies: that the substance used for storing thermal energy is a salt. that the salt is a supercritical salt solution in the form of a hydrate. that the supercritical salt solution comprises magnesium nitrate. that the barrel is triangular in shape with a bore centered in the barrel, and includes three cavities arranged so as to be distributed around the bore.

[0009] Furthermore, according to the present invention, an improved ejection device arranged with a barrel has been achieved.

[0010] Furthermore, according to the present invention, an improved method for storing thermal energy in a barrel has been achieved, characterized by the fact that the barrel is arranged with at least one bore and at least one cavity comprising a thermal storage substance where thermal energy generated when launching a projectile in the barrel heats up the barrel and at least parts of the thermal energy are stored in the thermal storage substance.

[0011] According to additional aspects of an improved method according to the invention, the following applies: that the barrel can be heated since the thermal storage substance can be caused to undergo a phase conversion from liquid to solid form and thus generate heat.LIST OF FIGURES

[0012] The invention will be described below by reference to the figures that are included there:Fig. 1 shows a barrel in a view from the short side according to one embodiment of the invention.Fig. 2 shows a barrel in a view from the lengthwise extent of the barrel according to one embodiment of the invention.DETAILED DESCRIPTION OF EMBODIMENT

[0013] The present invention points to a new and alternative design of a barrel intended for barrel-based launchers. An ejection device, also termed a cannon, a howitzer, or a piece, in the sense of an artillery piece, has the goal of making use a propellant for the purpose of firing a projectile. Preferably, a propellant, such as gunpowder, is initiated in one part of the cannon, oftentimes a chamber specifically adapted to the purpose. Initiation takes place by way of igniting thefuze, for instance by means of an ignition cartridge or an igniter in a munitions device, which is initiated by means of striking. Other methods for igniting the propellant may include ignition of the propellant by means of laser energy or electric energy. The propellant bums at a high rate and results in large amounts of gas being produced, which creates a gas pressure in the chamber which propels the projectile out of the barrel of the firing ejection device. The propellant has been adapted in order to generate a constant pressure on the projectile during the entire barrel procedure, to the greatest extent possible, as the projectile moves in the barrel, which results in the projectile leaving the mouth of the barrel with high speed. During the firing process, thermal energy from the combustion will heat the barrel. Additionally, friction between the projectile and the barrel will cause the barrel to heat up.

[0014] Projectiles, such as various types of grenades, generally include some form of operational part and some form of fuze which initiates the operational part. Barrels can be of different types where contact fuzes are common for projectiles that are meant to burst when in contact with an object, time fuzes when the projectile is meant to burst at a certain predetermined time and proximity fuzes when the projectile is meant to burst when an object comes within a certain distance from the projectile. The use of zone barrels is preferred when confronting flying vessels, while timed barrels can be used when confronting a large number of various objects. It is advantageous to combine various types of barrel functions in one and the same barrel, for instance in order for the projectile to burst after a certain time if it fails to detect any object, and so on.

[0015] It is advantageous for the operational part to comprise some type of explosive substance, as well as some type of shattering casing which encloses the explosive substance. Various types of propellants, such as fins, can furthermore be arranged in either the barrel or in its own subcomponent.

[0016] In order to stabilize the projectiles after the projectiles have left the barrel, the projectiles are preferably designed with rotation or with fins. Incases where the projectiles are designed with rotation, the projectiles are said to be rotationally stabilized and in cases where the projectiles are arranged with fins, the projectiles are said to be fin-stabilized. Fin-stabilized projectiles should have no rotation, or low rotation, when leaving the barrel.

[0017] To achieve rotation on the projectiles, the barrel is often designed with rifling, to which the projectile connects during the firing process. Rifling means that the barrel in a firearm, the barrel, is provided with spiral-shaped rifling. The opposite is smooth-bore barrel. When the rifling engages the projectile during firing, it rotates along its longitudinal axis. Due to the rotation, minor irregularities or damage to the projectile will not cause a drift in the trajectory of the projectile. Rotation is also necessary for an elongated (torpedo-shaped) projectile to maintain its direction after leaving the barrel and not start tumbling around. This is referred to as the projectile being rotation-stabilized. In smooth-bore weapons, only round (spherical) projectiles or fin-stabilized projectiles can be fired. An elongated projectile without fins will tumble as it leaves the muzzle.

[0018] Thus, rifling consists of grooves that are integrated into the track of the barrel, and the elevation in between is referred to as barriers. The rifling of fine- caliber firearms usually consists of four grooves that are turned to the right, while cannons, such as artillery pieces, have more grooves depending on the caliber of the launching device. In order for the rifling to be able to engage the projectile, the projectile must either be slightly larger than the diameter between the barriers, which is common for fine-caliber weapons, or be equipped with a special flange, called a belt, which has a slightly larger diameter than the barriers, which is common in projectiles with a diameter greater than 20 mm. The belt can be made out of plastic, composite material or a soft metal, such as brass.

[0019] Most barrels include rifling, and, by arranging projectiles with sliding belts, both rotation-stabilized and fin-stabilized projectiles can be launched with rifled barrels. Smooth-bore barrels are basically only used for weapon systems intended to armored combat vehicles, as the rotation of the projectilemeans that the directed explosive action, RSV, is less effective since the centrifugal force causes the beam to be spread out.

[0020] When the projectile connects to the barrel, friction arises which causes the barrel to be heated up. In addition, the combustion of the gunpowder will cause the barrel to be heated up. Heating the barrel causes a number of different problems, for example the life of the barrel can be affected, furthermore the size of the barrel can change and furthermore the heat of the barrel can inadvertently initiate the propellant and thus fire a projectile which can entail risks for one's own squad or own equipment or alternatively reduce the ability to fight the enemy and thereby potentially endangering one’s own safety. Unintentional initiation is called "cooking off".

[0021] To prevent heating, different forms of cooling can be used. This includes different forms of cooling media that are pumped or circulated in channels arranged on or in the barrel. Furthermore, the barrel can be arranged with cooling fins for purposes of removing heat from the barrel. Barrels are also preferably manufactured with a certain material thickness to be able to handle heating effects during the use of the barrel.

[0022] By arranging the barrel with a suitable substance, for example a salt, dissolved to prepare a supersaturated solution, an effective temperature regulation can be achieved.

[0023] A supersaturated solution, also known as a supercritical solution, is a solution containing more of a solute than what the solution should in fact contain according to conventional chemistry. This can happen when a soluble substance is poured into a hot solvent and, subsequently, when the solution has cooled down and is unable to be crystallized out. This principle is known, for example, from conventional hand warmers which often contain a solution consisting of sodium acetate and water. When hand warmers, often in the form of a plastic bag filled with the solution, are heated, the sodium acetate dissolves in the waterand a saturated solution is formed. During the heating process, the salt absorbs thermal energy. When the bag is subsequently cooled down, the salt is unable to regain its structure, since it lacks any means to build up crystals. It turns into a supersaturated and undercooled melt, which is very unstable.

[0024] For the excess salt to precipitate out and release the stored energy as heat, only a very small disturbance is required. Thus, to initiate a hand warmer, the user can click on a metal plate, preferably a plate of ferrous steel with microscopic grooves where molecules of sodium acetate in solid form are present. The metal plate is placed inside the device, the bag, to start the reaction. When the metal plate is bent back and forth, crystals are released from microscopic cracks in the metal. This means that the melt acquires the crystals, sprouts, which are required to start the crystallization by means of nucleation. An exothermic reaction then takes places, by which crystals of sodium acetate are formed and the heat is released. Heating up the supersaturated solution makes it possible to repeat the process.

[0025] The most common one of the salts to be used in hand warmers is sodium acetate trihydrate, with the chemical formula:CHsCOONa 3 H2O

[0001]

[0026] The melting point of sodium acetate trihydrate is 58°C, which is the maximum temperature a hand warmer containing sodium acetate trihydrate reaches when the crystallization process is started. For hand warmers, the chemical substance, sodium acetate, is chosen so that a suitable temperature is reached without harming the user of the hand warmer. For industrial processes, other substances can be chosen with both higher and lower melting points.

[0027] The chemical formula for the exothermic reaction with sodium acetate trihydrate is:CH3COO- (I) + Na+(I) CHsCOONa ■ 3 H2O (s) [2]

[0028] Other substances that may be used include:Magnesium nitrate hexahydrate with the chemical formula:Mg(NO3)2■ 6 H2O [3]Thiohydrate of sodium sulfate with the chemical formula:Na2SO4 - 10 H2O [4]

[0029] Or other solutions including gray copper sulfate, CuSO4, lithium nitrate LiNOs or sodium thiosulfate, Na2S20s.DESCRIPTION OF FUNCTIONS

[0030] A launching device is provided for firing, firing, projectiles with a propellant charge. The propellant charge, which can be gunpowder, for example, burns after initialization and generates a high pressure that drives the projectile out of a barrel. The projectile is arranged in the barrel by a method called hiring, it is common for a belt enclosing the projectile to be deformed relative to a groove arranged in the barrel which retains the projectile in the barrel. The propellant charge is arranged in what is often called a chamber in which the propellant charge is combusted during the generation of gases, gunpowder gases, which cause the projectile to move in the barrel. Preferably, a continuous / constant pressure is created in the chamber which also fills the barrel behind the projectile as it moves towards the mouth of the barrel.

[0031] Problems with firing projectiles arranged with a belt included the belt causing wear on the barrel as we as the seal between the projectile and the barrel loosening, thus enabling the entry of gunpowder gases, which affects the launch process, among other things by the fact that it results in theprojectile launch speed, VO, varying between different projectiles depending on differences in the seal between the projectile and the barrel. By controlling the temperature of the barrel, the tolerance of the bore in the barrel can be controlled and thus improve the connection between the belt and the barrel.

[0032] Fig. 1 shows the barrel 10 seen from the short side, the radial part of the barrel, with a barrel opening 20. In the embodiment shown, the barrel 10 three sided or triangular shape, but can also be of a different geometric shape and be adapted on the basis of, for example, advantages related to the manufacturing techniques. The barrel is designed with a number of cavities 12, 14, 16, including temperature storage substance. The barrel is designed with a certain material thickness 30 which can be variable. The geometry of the cross-section 20 of the barrel opening, the bore, and cavities 12, 14, 16 are processed in the barrel with conventional processing methods such as, for example, various forms of cutting processing including reaming. The cross section 20 for the geometry of the barrel opening can also be called the course of the barrel. The barrel 10 can also be manufactured by additive manufacturing methods. The advantages of a triangular shape on the barrel are that the cavities 12, 14, 16 can be arranged symmetrically around the cross-section 20 so that the heat is distributed evenly around the cross-section 20 when projectiles are fired in the barrel.

[0033] The temperature storage substance stores thermal energy and can, for example, be a salt or a salt solution, for example a supersaturated salt solution, and is arranged in cavities 12, 14, 16.

[0034] When ammunition is fired from a barrel, thermal energy from the combustion of the propellant in the chamber, the spread of combustion gases in the firing tube, and frictional heat from the movement of the projectile in the barrel lead to the barrel being heated up. The thermal energy from the heating process will be distributed throughout the barrel and, in whole or in part, enclose the temperature storage substance arranged in cavities 12, 14, 16. The thermal energy can be stored in the temperature storage substance, for example by thetemperature storage substance undergoing a phase transformation. The temperature storage substance is preferably initially in solid form, and, during the heating process, thermal energy is accumulated in the temperature storage substance and a phase transformation to liquid form can occur if the generated thermal energy is sufficient for the temperature storage substance in the entirety of the cavity 12, 14, 16 to undergo a phase change. Following the ejection process with subsequent heating is completed, the temperature storage substance will cool down and revert to solid form. In the event that the temperature storage substance has undergone a full phase change and is thus in liquid form, a nucleation can be initiated in order to bring about renewed crystallization of the temperature storage substance. Initiation can take place by electrically, chemically or mechanically arranging at least one molecule in solid form of the temperature storage substance in the supersaturated solution in liquid form. Examples of methods for initiation may include the arrangement of a metal plate comprising cracks where crystals of the temperature storage substance are enclosed in solid form which can be released by mechanical deformation of the metal plate, for example by electromagnetical ly deforming the metal plate.

[0035] In an alternative embodiment, a eutectic mixture is used as the temperature storage substance. A eutectic mixture or eutectic of two substances is a mixture with such a composition that the melting point is the lowest possible, and in any case lower than that of the two individual substances. It is only in an atomic / molecular mixing ratio that the composition melts as a whole at a specific temperature (the eutectic temperature) and forms a superlattice, releasing all its components into a liquid mixture. The eutectic point represents the lowest temperature for which the liquid phase of a mixture can exist. In a eutectic mixture, the phases change between molten and solid form instantaneously, when the eutectic temperature is passed. In mixtures other than the eutectic one, a certain temperature range prevails as the mixture gradually transitions from one state of aggregation to the other. Within this range, the mixture has a viscous consistency.

[0036] Fig. 2 shows the barrel 10 seen from the long side in cross-section, the radial part of the barrel, with a barrel opening, a bore 20 and two cavities 14, 16, whereas the third cavity 12 is not visible in the section in question. Furthermore, a chamber 40 is shown where the projectile and propellant are arranged, either in the form of cased ammunition, that is, where the projectile is arranged in a sleeve comprising a propellant and may also include an initiator arranged for the propellant or, alternatively, in the form of a separated projectile and propellant which is common with coarser calibers. Furthermore, inlets 50, 52 are shown, whereas the temperature storage substance can be arranged a control device for the temperature storage substance, if any, can be arranged. The control device can include different sensors, for example temperature sensor or sensors used for measuring the form of the temperature storage substance, for example solid form or liquid form. Furthermore, various forms of devices can initiate or otherwise change the prevailing state of aggregation (also referred to as the form of aggregation). Each respective cavity 12, 14, 16 can be designed as a cavity running over the entirety of the barrel, alternatively running along part of the barrel, or alternatively be divided into several separate units along the axial extent of the cavities 12, 14, 16.EXAMPLES OF EMBODIMENTS

[0037] Examples of caliber are 20-155 mm and a length of the barrel of between 1 m and 10 m.ALTERNATIVE EMBODIMENTS

[0038] The invention is not limited to the embodiments specifically shown, but can be varied in different ways within the framework of the claims.

[0039] For instance, it is clear that the number, size, material and shape of the elements and details included in the barrel are to be adapted according iito the projectile(s) and projectile compositions, along with other construction- related properties, which are applicable to each individual case.

[0040] For instance, the projectile can be arranged so that it is capable of exploding, emitting shrapnel, catching fire, exerting a thermobaric effect, fighting fires, to be used as a training projectile, in light kits, in smoke kits, to exert electromagnetic effect, bring about electromagnetic disturbances or other loads and functions.

Claims

Claims1 . Barrel (10) for a launch device (1 ), where the barrel (10) is arranged with a bore (20) for launching projectiles with a propellant charge, characterized in that the barrel (10) is arranged with at least one cavity (12, 14, 16) where a substance for storing thermal energy is arranged in the cavity (12, 14, 16), and in that the barrel (10) is triangular in shape with a bore (20) centered in the barrel, and includes three cavities arranged so as to be distributed around the bore.

2. Barrel (10) for a launching device (1 ) according to claim 1 , characterized in that said substance for storing thermal energy is a salt.

3. Barrel (10) for a launching device (1 ) according to claim 2, characterized in that the salt is a supercritical salt solution in the form of a hydrate.

4. Barrel (10) for a launching device (1 ) according to claim 3, characterized in that the supercritical salt solution comprises magnesium nitrate.

5. Firing device (1 ) arranged with a barrel (10) according to any of claims

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