The present invention relates in general to the field of munitions. More specifically, this invention relates to an improved means of cooling the barrel of a weapon, which offers the potential to reduce its weight, to remove the need for a second barrel, and to improve its barrel life. In particular, the present invention uses a thermoelectric device to convert the energy from the heat produced by a hot barrel during operation, to power a fan that cools the barrel.
The weight reduction of small arms weapons is a significant concern for a soldier. A significant portion of the weight of individual and crew served weapons is in the barrel of the weapon. Much of the additional weight is necessary, not only to withstand the pressure of firing the cartridge, but also as a heat sink to absorb the thermal energy of firing the weapon.
In fact, machine guns typically have a removable, secondary barrel for the purpose of replacing the barrel after firing for a short time, in order to allow the primary barrel to cool. This additional barrel adds weight and complexity to the weapon.
What is therefore needed is a device for cooling the weapon barrel with significant weight reduction. In other terms, it would be desirable to solve the cooling problem and to remove the redundant weight associated with the need for a second barrel. Furthermore, since the barrel life is primarily a function of the barrel temperature, barrels fired at lower temperatures last significantly longer. As a result, it would be desirable to extend the life of the barrel by reducing its operation temperature. Prior to the advent of the present invention, the need for such a cooling means has heretofore remained unsatisfied.
The present invention satisfies this need, and describes a barrel cooling device and method (collectively referred to as “the present device,” “the present method”, or “the present system”). The present device captures the energy from the heat produced by a hot barrel during operation, and converts the captured energy into electric power that energizes one or more thermoelectric fans to cool the barrel.
Barrel cooling typically occurs through natural convection of the airflow around the barrel. Generally, forced air convection can result in significant improvement of cooling compared to natural convection. The barrel cooling device of the present device uses the heat of the barrel during firing as a means to cool the barrel.
The barrel cooling device uses a thermoelectric generator that is mounted to the barrel, which produces electricity as the barrel heats up from firing. The generated electrical current drives a series of electric fans to cool the barrel.
The thermoelectric effect is the direct conversion of temperature differences to electric voltage and vice-versa. A thermoelectric device creates a voltage when there is a difference in temperature on opposite sides of semiconductors to produce electrical energy.
To this end, when the thermoelectric device is placed on a hot barrel it uses the recaptured heat energy to power a series of thermoelectric fans. This effect accelerates the air cooling of the barrel. A cooler barrel increases the lifespan of the barrel, and allows the weight of the barrel to be reduced because less material is required for a heat sink.
The above and other features of the present invention and the manner of attaining them, will become apparent, and the invention itself will be best understood, by reference to the following description and the accompanying drawings, wherein:
Similar numerals refer to similar elements in the drawings. It should be understood that the sizes of the different components in the figures are not necessarily in exact proportion or to scale, and are shown for visual clarity and for the purpose of explanation.
While four thermoelectric fans 200, 205, 210, 215 are shown in
In one embodiment, the thermoelectric fans include three thermoelectric fans 205, 210, 215 that are generally equally spaced between the gas block and the chamber, and a fourth thermoelectric fan 200 that is located between the gas block and the front sight of the machine gun.
As used herein, thermoelectric fans are electric fans that are powered by the thermoelectric effect. The thermoelectric effect is also referred to as the Seebeck effect, and is used to generate electricity. Generally, the thermoelectric effect encompasses three separately identified effects: the Seebeck effect, the Peltier effect, and the Thomson effect.
In general, a thermoelectric device includes one or a series of p-type semiconductor elements and one or a series of n-type semiconductor elements that are electrically connected. When the two dissimilar elements are subjected to different temperatures, the Seebeck effect causes a voltage to be generated across the junctions between the p-type and n-type semiconductor elements.
With further reference to
In
As more clearly illustrated in
The modules 315 are electrically connected to the electric fan 300, to supply it with the desired energy. As illustrated in
The electric fan 300 has an open end that is secured to the barrel 15, by means of a mechanical device, such as a clamp or a similar device, to form a cooling chamber 331 therewith. As shown in
In the preferred embodiment of
While
The thermoelectric device 310 may be comprised of any available or suitable thermoelectric modules, such as the HZ-2 thermoelectric modules from Hi-Z Technology, Inc. Quantum well and lead telluride modules or other available thermoelectric devices may be used.
The electric fan model PSD1204PBB1-A from SUNON, or any other suitable or available electric fan may be used. The electric fan 300 may, for example, be approximately 40 mm×40 mm×24 mm in dimensions, and can produce approximately 21.6 CFM of airflow.
The wire 320 may for example be nickel plated copper insulated with mica tape and a fiberglass jacket. It should be noted that other suitable conductors may alternatively be used.
When the thermoelectric device 310 is placed in contact with the hot barrel 15, it uses the recaptured heat energy to power the electric fan 300, which will accelerate the air circulation within the cooling chamber 331, to cool the barrel 15. This increases the lifespan of the barrel 15, and has the potential to reduce the weight of the barrel 15 because less material is required for a heat sink.
The electric fan 400 has an open end that is secured to the thermoelectric device 410 to form a cooling chamber 431 therewith. In turn, the thermoelectric device 410 is secured to the barrel 15, and is disposed next to the electric fan 400.
Alternatively, the electric fan 400 is secured to the barrel 15 by means of a mechanical device, such as a clamp or a similar device, with the thermoelectric device 410 sandwiched therebetween.
In a preferred embodiment, the electric fan 400 includes a curved bottom 407 that matches the shapes of both the barrel 15 and the thermoelectric device 410. The thermoelectric device 410 is made of a generally rectangularly shaped, curved, ribbon that is adhered or glued onto the curved bottom surface 407 of the electric fan 400.
With reference to
The support structure 505 retains the electric fan 500 a predetermined, optimal distance above the barrel 15 and forms a cooling chamber 531 therewith. The support structure 505 is open at both ends.
In the embodiment of
With reference to
The support structure 605 includes a curved bottom 607 that matches the shapes of both the barrel 15 and the thermoelectric device 610. The thermoelectric device 610 is made of a generally rectangularly shaped, curved strip 612 that can be adhered to, or glued onto the curved bottom 607 of the support structure 605. Alternatively, the thermoelectric device 610 can be secured to the barrel 15, and disposed next to the electric fan 600.
In use, as the barrel 15 heats up during operation, it generates heat energy that is captured by any of the thermoelectric devices 310, 410, 510, 610. In turn, as explained earlier, the thermoelectric device, e.g., 310 automatically converts the captured heat energy into an electric current that is transmitted to the electric fan, e.g., 300, via the conductor 320. The electric fan 300 provides the desired cooling effect to the barrel 15.
In summary, the electric fan, e.g., 300 is automatically powered by the heat emanating from the barrel 15, to cool the barrel 15. It should be understood that the other thermoelectric fans 205, 210, 215 that form the cooling device 100 operate similarly to the thermoelectric fan 200 to respectively cool adjacent sections of the barrel 15. It should also be understood that the different thermoelectric fans 200, 205, 210, 215 are included here to illustrate several different potential fan configurations, and that a single configuration may be used for all thermoelectric fans in the device.
Experimentally, and with further reference to
Each one of the thermoelectric fans 200 requires approximately 6 Watts of power at 12 Volts, which can be achieved using 3 to 4 thermoelectric devices per electric fan.
With reference to
It should be understood that other modifications might be made to the present design without departing from the spirit and scope of the invention.
The invention described herein may be manufactured and used by, or for the Government of the United States for governmental purposes without the payment of any royalties thereon.
Number | Name | Date | Kind |
---|---|---|---|
1328230 | Johnston | Jan 1920 | A |
1371351 | Cassetta et al. | Mar 1921 | A |
1413903 | Czegka | Apr 1922 | A |
1527585 | Laurens et al. | Feb 1925 | A |
1543262 | Methlin | Jun 1925 | A |
1551617 | Pohlmann | Sep 1925 | A |
2042449 | Baumann | Jun 1936 | A |
4463653 | Pusch et al. | Aug 1984 | A |
4982648 | Bol et al. | Jan 1991 | A |
5092157 | Achter et al. | Mar 1992 | A |
5092220 | Rounbehler | Mar 1992 | A |
5098451 | Rounbehler et al. | Mar 1992 | A |
5117734 | Rhoads | Jun 1992 | A |
5202530 | Stephens | Apr 1993 | A |
5726375 | Adams et al. | Mar 1998 | A |
6461752 | Leung | Oct 2002 | B1 |
6679156 | Danou | Jan 2004 | B1 |
6705195 | Thornton | Mar 2004 | B1 |
7563097 | Lavigna et al. | Jul 2009 | B2 |
7594463 | Skinner | Sep 2009 | B2 |
20040094025 | Meissner et al. | May 2004 | A1 |
20070039224 | Skinner | Feb 2007 | A1 |
Entry |
---|
“The Solid State Conversion of Heat to Electricity,” Hi-Z Technology, Inc. Jul. 11, 2011, available at: http://www.hi-z.com/index.php. |
Sunonwealth Electric Machine Industry Co., Ltd. Jul. 11, 2011, available at: http://www.sunon.com. |
Fairbanks, John W. “Thermoelectric Developments for Vehicular Applications,” Diesel Engine-Efficiency and Emissions Research (DEER) Conference, Detroit, MI. (Aug. 24, 2006). Available at: http://www1.eere.energy.gov/vehiclesandfuels/pdfs/deer—2006/session6/2006—deer—fairbanks.pdf. |