Impulse and momentum transfer devise

Abstract

This invention concerns a device for the transmission of impulse and momentum, e.g. from a shock wave from an explosion or momentum from objects impacting the device, from one location to another, and is primarily used to protect vehicles, ships, aircrafts and buildings against impulse and/or momentum, for instance in regards to attacks on those with grenades, bombs, mines and the like. The governing physical principles are those of conservation of momentum and energy, and Newton's 3rd Law, claiming that for every action there is an equal but opposite reaction. When the receiver 1 is accelerated by the incoming shock wave 9 it collides with the transmitter 2, connected to an emitter 3, momentum is transferred to the emitter 3. If the transfer is in itself not sufficient to bring the receiver's 1 velocity to an acceptable level, additional energy and momentum is added through the transmitter 2.

Claims

1. A method of reducing momentum absorption by an object, comprising: a. providing a receiver configured to be accelerated by an incoming shock wave; b. providing a transmitter comprising continuous rods, the transmitter receiving momentum from the accelerated receiver; and c. configuring an emitter for ejection of material contained in a resin in response to receiving momentum from the transmitter.

Description

DRAWINGSFIGURES

(1) FIG. 1a: Example of a passive embodiment of the impulse and momentum transfer device used for side protection of a vehicle.

(2) FIG. 1b: Example of an active embodiment of the impulse and momentum transfer device used for side protection of a vehicle.

(3) FIG. 2a: Example of an active embodiment of the impulse and momentum transfer device used for belly protection of a vehicleprior to activation.

(4) FIG. 2b: Example of an active embodiment of the impulse and momentum transfer device used for belly protection of a vehicleduring activation.

(5) FIG. 3a: Example of transmitter 2 designs used in some embodiments able to add energy and momentum using an energy source based on pyrotechnics or explosives.

(6) FIG. 3b: Example of transmitter 2 designs used in some embodiments able to add energy and momentum using an electric energy source.

(7) FIG. 4a: Example of an embodiment of the emitter 3 with liquid or powder/granules.

(8) FIG. 4b: Example of an embodiment of the emitter 3 with liquid or powder/granulesduring activation.

(9) FIG. 5: Principle sketch of a railgun.

(10) FIG. 6: Principle sketch of a coilgun.

(11) FIG. 7: Example of impulse and momentum transfer device.

(12) FIG. 8: Example of impulse and momentum transfer device.

(13) FIG. 9: Example of impulse and momentum transfer device.

DETAILED DESCRIPTION

(14) It is the purpose of the invention to prevent or minimize the momentum absorptionand thus local and global acceleration (s)in for instance the protected part(s) of a vehicle, ship, aircraft or building.

(15) This is achieved by a protective device, as stated initially, which is particular by further including a transmitter 2 designed to transmit impulse and/or momentum to an emitter 3 comprising an ejectable mass.

(16) The governing physical principles are those of conservation of momentum and energy, and Newton's 3rd Law, claiming that for every action there is an equal but opposite reaction.

(17) When the receiver 1 is accelerated by the incoming shock wave or an object having momentum, the receiver 1 transmits its momentum through the transmitter 2 to the emitter 3. By doing so, the emitter 3 is ejected away from the vehicle, ship, aircraft or building. In the passive case, where there are no energy and momentum added in the transmitter 2, the receiver 1 will lose its momentum to both the transmitter 2 and emitter 3. In the following totally inelastic case it is assumed, that the transmitter 2 and the emitter 3 have zero initial velocity and that the transmitter 2 velocity remains zero after momentum transfer:

(18) $\begin{array}{cc}{m}_r{v}_{r1}+m_{1}0+m_{e}0=m_r{v}_{r2}+m_{1}0+m_e{v}_e.Math.& \left(1\right)\\ v_e=\frac{m_r\left(v_{r1}-v_{r2}\right)}{m_e}& \left(2\right)\end{array}$
Where:
m.sub.r is the mass of the receiver 1,
v.sub.r1 is the velocity of the receiver 1 immediately before the transfer of momentum through the transmitter 2, (generated by external impulse and/or momentum),
v.sub.r2 is the velocity of the receiver 1 after momentum transfer,
m.sub.t is the mass of the transmitter 2,
m.sub.e is the mass of emitter 3 and
v.sub.c is the velocity of the emitter 3 after momentum transfer,
For the energy we have:

(19) $\begin{array}{cc}\frac{1}{2}{m}_r{v}_{r1}^2+\frac{1}{2}{m}_t{0}^2+\frac{1}{2}{m}_e{0}^2=\frac{1}{2}{m}_r{v}_{\mathrm{r2}}^2+\frac{1}{2}{m}_t{0}^2+\frac{1}{2}{m}_e{v}_e^2& \left(3\right)\end{array}$
By inserting equation (2) into equation (3) and simplifying we have:

(20) $\begin{array}{cc}{v}_{r2}=\sqrt{\frac{m_r{v}_{r1}^2-m_e{v}_e^2}{m_r}}& \left(4\right)\end{array}$

(21) Energy and momentum can be supplied through for instance pyrotechnic and explosive materials or by using electromagnetic fields. By adding momentum H, corresponding to the energy E, these are added on the left hand side of equation (1) and (3), respectively. Hence, equation (4) is rewritten to:

(22) $\begin{array}{cc}{v}_{r2}=\sqrt{\frac{m_r{v}_{r1}^2-m_e{v}_e^2-2E}{m_r}}& \left(5\right)\end{array}$

(23) By optimizing the values of the terms, the mass of the receiver 1, m.sub.r, and the mass of emitter 3, m.sub.e, as well as the added momentum, H, and the energy input, E, is it possible to reduce the velocity of the receiver 1, v.sub.r2, after impulse and momentum transfer, down to approximate zero, or below a desired value.

(24) In general, the receiver 1 is stopped, usually before it collides with the protected parts of the vehicle, ship, aircraft or building. Hereby local and/or global acceleration(s) of the vehicle, ship, aircraft or building are prevented or minimized.

(25) By measuring the velocity of the receiver 1 prior to impact, v.sub.r1, a fast control system is able to control the amount the added amount of momentum and energy in order to adjust the response within a given rang. This is particularly the case for an electric system.

EMBODIMENTS

(26) In accordance with one embodiment, a protective device comprises a transmitter 2 and an emitter 3. The transmitter 2 is transferring energy and momentum from a receiver 1, i.e. a face or surface under attack to an emitter 3 that is ejected in a somewhat opposite direction relative to the attack.

(27) The receiver 1 may be V-shaped, where the bottom of the V is facing the incoming impulse or objects having momentum. It provides a partial deflection of these, so that the momentum absorbed in the receiver 1 is reduced. The receiver 1 may in some cases be integrated directly into the surface (side, bottom, roof, ceiling or wall), it is to protect.

(28) The receiver 1 can be made in one or more materials with high acoustic velocity. Such materials have in experiments shown better performance in terms of dissipation of shock waves. A typical material might be high-strength steel. The receiver 1 can also be made in one or more materials with high ballistic resistance (ballistic limit). This is crucial to avoid that objects having momentum perforate the receiver 1 and thereby impact the parts of the vehicle, ship, aircraft or buildings that are to be protected. Material possibilities include armor steel, ceramics and Kevlar.

(29) In other cases, the receiver 1 can be entirely or partially made of materials with low acoustic velocity and great elasticity to reduce the dynamic pressure, also referred to as the reflected pressure. This reduces the shock impact and the maximum reflected pressure significantly. The total impulse from the shock wave (9) is in principle not reduced though, as the duration of the impulse is extended. By doing so, additional time to initiation and operation of energy and momentum adding elements is gained. A suitable material could be certain high density polymers (HDP).

(30) The transmitter 2 can be made as a passive member, such as continuous rods or fluid-filled pipes that can carry the momentum from the receiver 1 to the emitter 3. In particular, in the passive casebut also in the reactive or active caseit is crucial that material properties (e.g. mass and stiffness) and design are attuned to both the receiver 1 and emitter 3, thereby achieving maximum momentum transfer within a given range.

(31) The transmitter 2 used in some embodiments is able to add energy and momentum when made as continuous elongated cylinders, containing an energetic substance and an internal piston. The energetic substance of pyrotechnic or explosive nature, is ignited or initiated and adds momentum to both the emitter 3 and hence the receiver 1in opposite directionsaccording to the same principle as in a gun, where the emitter 3 is the shot being lunched and the receiver 1 corresponds to the recoiling gun.

(32) In some embodiments the transmitter 2 is able to add energy and momentum, e.g. as rods with coils 2i or rails 2e and armatures 2h capable of performing mechanical work when an electrical current is passed through. The principles are known as coil and railgun. Especially, the railgun principle is desirable, since the reaction to the receiver's 1 action is communicated through the momentum carrying field, straight to the rear end of the rails 2e, where it is acting directly on the emitter 3. In both methods, the transmitter 2 serves as a gun in the same manner as described above.

(33) The transmitter 2 used in some embodiments is able to add energy and momentum reactively as the receiver's 1 motion relative to the transmitter 2 and the emitter 3 by example, say by percussion caps or by an electric motion switch, switching current when the receiver 1 distance traveled or achieved speed exceeds a predetermined size. This obviates the need for sensors that can be inhibited by mud, water, direct jamming and the like.

(34) The transmitter 2 used in some embodiments is able to add energy and momentum actively on a signal from a sensor. Sensors, such as radar, pressure transducers or thermo-couples can be used to pre-activate the transmitter 2, so that the receiver 1 gets momentum in a direction away from the vehicle, ship, aircraft or building prior to blast or objects having momentum impact the receiver 1. This allows the required power (energy per. time unit) to be reduced and the ejection of the emitter 3 less violent reducing third party risk.

(35) The emitter 3 is the part that is to carry the momentum away from the protected vehicle, ship, aircraft or building. Depending on the situation and the platform on which it is used, it can either be an advantage to obtain very high speed or a lower speed. Regardless of the direction or area in which it is ejected, it is important that it is brought to a halt as fast as possible, to avoid or minimize the risk to third parties. The proposed emitter 3 in this invention will therefore often be in the form of containers in a disintegrating material containing liquid or powder/granules. The latter can also be tied in resin to increase the energy and momentum absorption when it disintegrates during the acceleration. Once the emitter 3 is accelerated due to momentum obtained from the transmitter 2, one may seek to add a mechanical shock, which disintegrates the containers and only liquid or powder/granules are ejected in the desired direction or area. Liquid and powder/granules will rapidly lose momentum due to air resistance and/or gravity. If deemed necessary, the used container may be fitted with a parachute system. In special cases, the emitter 3 simply is the opposing receiver 1.

(36) The emitter 3 can principally be placed arbitrarily, from where ejecting is considered appropriate. In special cases the emitter 3 is a gas, which is ejected as supersonic flow.

(37) The transmitter 2 used in some embodiments is entirely or partially containing or surrounded by the emitter 3, e.g. by lunching the emitter 3 through the transmitter 2like a shot lunched from a gunor alternatively as supersonic flowsimilar to a rocket. In some embodiments the transmitter 2 is integrated with the receiver 1 so that at least parts of the energy and momentum added take place in the receiver 1. Additionally, some embodiments may comprise a multistage receiver 1transmitter 2emitter 3 system to perform impulse and momentum transfer. This will make it possible to reduce the local effects of initiation and the operation of energy and momentum adding elements as these are distributed.

(38) The transmitter 2 used in some embodiments is closely integrated with the emitter 3 so that at least parts of the energy and momentum added take place in the emitter 3.

(39) The transmitter 2 used in some embodiments is closely integrated with the receiver 1 so that at least parts of the energy and momentum added take place in the receiver 1.

(40) The transmitter 2 used in some embodiments is made as a multi-loop system, which makes it possible to place energy sources in the periphery of the system and have current loops in both directionsboth to the receiver 1 and emitter 3. This will make it possible to reduce the local effects of switching high currents and the operation of energy and momentum adding elements as these are distributed.

DETAILED DESCRIPTION OF THE DRAWINGS

(41) In the following the invention is explained based on examples of how it could be implemented on a ground vehicle with regards to the schematic drawings.

(42) FIG. 1a, FIG. 1b, FIG. 2a and FIG. 2b: The figures are based on that the impulse and momentum transfer device is used as blast and/or fragmentation protection of a vehicle's side and belly. On the figures it is shown how the explosion 10 generates a shock wave 9 impacting the receiver 1. The left hand side of FIG. 1a and FIG. 1b shows a collision with an object 11 having momentum, and on the right hand side of FIG. 1a and FIG. 1b is illustrated a shock wave 9 from an explosion 10. The operation of the invention found in FIG. 1a and FIG. 1b is only shown for the impulse from the shock wave 9. In FIG. 2b the shock wave 9 from an under-belly explosion 10 is illustrated. The operation of the invention found in FIG. 2b is only illustrated for the under belly shock wave 9. The receiver 1, gaining momentum 4, from the shock wave 9, which is transferred as forces 6 in the transmitter 2.

(43) Reactions to these forces 6 are generated as a result of acceleration of the emitter 3, thereby gaining momentum 8, and possibly also by additional energy and momentum added in the transmitter 2see FIGS. 3a and 3b. Hence, the reaction forces 6 add momentum 7 to the receiver 1. If the system is properly tuned momentum 7 and momentum 4 cancel out.

(44) FIG. 3a: Example of transmitter 2 design used in some embodiments capable of adding energy and momentum. The transmitter 2 comprises a cylinder 2b and two pistons 2a, which is pushed away from each other, when the energy source 2c between them is released. Energy 2c and momentum generated in this example show the combustion of a pyrotechnic material or detonation of an explosive substance. Momentum 7, 8 is hereby added to the receiver 1 and the emitter 3.

(45) FIG. 3b: Example of transmitter 2 design used in some embodiments capable of adding energy and momentum. The transmitter 2 comprises a guiding body 2d and two rails 2e, where the electric current 2f runs and a guiding piston 2g and an armature 2h. The guiding piston 2g and the armature 2h are electrically isolated from each other. When the current is switched, for instance by the armature 2h is pushed in between the rails 2e, the Lorentz force acts on the current 2f through the armature 2h, which in turn act on the later, and further through the guiding piston 2g, and down towards the receiver 1. The reaction to this force is communicated through the field down to the rear end of the rails 2e.

(46) FIG. 4a and FIG. 4b: Example an embodiment of the emitter 3 with liquid or powder/granules. The emitter 3 in FIG. 4a and FIG. 4b is designed for vertical ejection, say, from the roof of a vehicle. Momentum 8 is transmitted through the transmitter 2 and continues through an acceleration plate 3a up into the ejectable mass of the emitter 3, stored in containers 3b. The screen 3c in the example shown, is mounted in order to avoid debris in an unwanted direction. The expected flow field 3d, after the disintegration of the containers 3b is shown in the FIG. 4a. It should be noted that both the content as well as the strength of the containers 3b may vary, and therefore it could be fluid in some, while powder/granules could be in others (within the same emitter 3). In simple embodiments, these can be e.g. water cans and sandbags.

(47) FIG. 5: This figure is only included to illustrate the theoretical principle of the Lorentz force in a railgun, and therefore described no further.

(48) FIG. 6: Principle sketch of coilgun. Current flows through the individual coils according to the position of the shot to maintain continuous acceleration.

(49) FIG. 7: Example of an embodiment of the impulse and momentum transfer device in which the transmitter 2 is integrated with the emitter 3. The emitter 3 is ejected through the transmitter 2.

(50) FIG. 8: Example of a multistage embodiment of the impulse and momentum transfer device.

(51) FIG. 9: Example of an embodiment of the impulse and momentum transfer device, in which the receiver 1 contains an energy and momentum source and is integrated with transmitters 2, in a multistage configuration with a number of emitters 3. The transmitters 2 may have decreasing power to distribute the effects of energy and momentum discharges. The device can also be configured as a multistage cascade system. Similarly, the device can be designed with energy and momentum sources in the emitter 3.