JP2007247996A - Electromagnetic accelerator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve flight characteristics of a missile in regard to an electromagnetic accelerator. <P>SOLUTION: A first conductive rail 11a, a first insulative rail 12a, a second conductive rail 11b, and a second insulative rail 12b are spirally twisted in parallel with each other to form a cylindrical body. A metal armature is put in an inner face space of the cylindrical body, and a large pulse like current is fed from base end sides of the first conductive rail 11a and the second conductive rail 11b by a pulse power supply 1. The metal armature 20 is not only accelerated in extending directions of the conductive rails 11a, 11b, but it is also rotated as it advances on the conductive rails 11a, 11b. By this, the missile flies while rotating after it is launched into space from tips of the conductive rails 11a, 11b, and its flight characteristics become stable. Since the metal armature 20 advances while rotating, a circumferential face of the metal armature evenly receives melting from Joule heat by energization, the symmetric shape of the metal armature is maintained, and the flight characteristics of the missile after launching into space becomes stable. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electromagnetic accelerator, and more particularly to an electromagnetic accelerator capable of improving the flight characteristics of a flying object after being injected into space.

Conventionally, a metal armature is sandwiched between a pair of parallel linear conductive rails, a large current flows between one conductive rail-metal armature-the other conductive rail, and a magnetic field generated by a current flowing through the conductive rail. The metal armature is accelerated in the extending direction of the conductive rail by the Lorentz force acting between the current flowing in the metal armature and the flying object from the tip of the conductive rail to the space (when only the metal armature becomes a flying object and the metal 2. Description of the Related Art There is known an electromagnetic acceleration device that emits an armature and a flying body main body integrated in front of the armature) (see Patent Document 1).
JP-A-7-311541

In the conventional electromagnetic accelerator, no force that rotates the metal armature works. For this reason, the flying object after being injected into the space from the front end of the conductive rail flies without rotating, and its flight characteristics become unstable. In addition, since the same part of the metal armature is always in contact with the conductive rail, the part is particularly damaged by Joule heat due to energization, and the shape of the metal armature is destroyed. This also makes the flight characteristics of the flying object after being ejected into space unstable.
Accordingly, an object of the present invention is to provide an electromagnetic accelerator capable of improving the flight characteristics of a flying object after being injected into space.

In a first aspect, the present invention provides a pair of parallel spiral conductive rails, a metal armature having a circular cross-sectional shape sandwiched between the conductive rails, and power supply from one end side of the conductive rails. The present invention provides an electromagnetic acceleration device comprising: one conductive rail-metal armature-the other conductive rail and a power supply device for passing a large current.
In the electromagnetic accelerator according to the first aspect, the pair of conductive rails have a parallel spiral shape. For this reason, the magnetic field generated by the current flowing through the conductive rail and the current flowing through the metal armature rotate as the metal armature travels through the conductive rail. For this reason, the metal armature is not only accelerated in the direction in which the conductive rail extends, but is also rotated as it travels through the conductive rail. Therefore, the flying object after being injected into the space from the front end of the conductive rail flies while rotating, and the flight characteristics are stabilized. Further, since the metal armature rotates with a slight delay from the rotation of the magnetic field due to the current flowing through the conductive rail, the portion of the metal armature that is in contact with the conductive rail is slipped off. For this reason, the peripheral surface of the metal armature is averagely melted by Joule heat due to energization, and the symmetrical shape of the metal armature is maintained. This also stabilizes the flight characteristics of the flying object after being injected into space.

In a second aspect, the present invention provides the electromagnetic accelerator according to the first aspect, wherein the conductive rail is formed of a metal fiber in a brush structure.
Although the conductive rail may be formed of a rigid body such as copper cut out, it takes a number of manufacturing steps.
Therefore, in the electromagnetic accelerator according to the second aspect, the conductive rail is formed of a metal fiber in a brush structure. In this case, since the conductive rail has flexibility, it can be formed in a parallel straight line first and then twisted to form a parallel spiral, thereby reducing the number of manufacturing steps. Also, electrical contact is improved.

In a third aspect, the present invention provides the electromagnetic accelerator according to the first aspect, wherein the conductive rail is configured to have a structure in which metal cloths are stacked.
Although the conductive rail may be formed of a rigid body such as copper cut out, it takes a number of manufacturing steps.
Therefore, in the electromagnetic accelerator according to the third aspect, the conductive rail is configured to have a structure in which metal cloths are stacked. In this case, since the conductive rail has flexibility, it can be formed in a parallel straight line first and then twisted to form a parallel spiral, thereby reducing the number of manufacturing steps. Also, electrical contact is improved.

  According to the electromagnetic acceleration device of the present invention, since the flying object after being injected into the space from the tip of the conductive rail flies while rotating, the flight characteristics become stable. Further, since the metal armature is maintained in a symmetrical shape, this also stabilizes the flight characteristics of the flying object after being injected into the space.

  Hereinafter, the present invention will be described in more detail with reference to embodiments shown in the drawings. Note that the present invention is not limited thereby.

FIG. 1 is an explanatory diagram illustrating a configuration of an electromagnetic acceleration device 100 according to the first embodiment.
The electromagnetic acceleration device 100 includes a pulse power source 1, an acceleration cylinder 10, and a metal armature 20.

The acceleration cylinder 10 includes an approximately 1/4 cylindrical first conductive rail 11a, an approximately 1/4 cylindrical first insulating rail 12a, an approximately 1/4 cylindrical second conductive rail 11b, It consists of a second insulating rail 12b having an approximately 1/4 cylindrical shape and a cylindrical outer cylinder 13.
The first conductive rail 11a, the first insulating rail 12a, the second conductive rail 11b, and the second insulating rail 12b are arranged circumferentially in this order to form a cylinder as a whole.
The 1st conductive rail 11a and the 2nd conductive rail 11b are comprised by the rigid body by cutting out copper.

  The pulse power source 1 feeds a pulsed large current from the base end sides of the first conductive rail 11a and the second conductive rail 11b.

  The metal armature 20 is, for example, a copper cylinder.

FIG. 2 is a cross-sectional view and a developed view of the acceleration cylinder 10.
The cross-sectional view is a view seen from the base end side in a circular shape at each position in the extending direction of the acceleration cylinder 10.
The developed view is a diagram showing the inner surface of the acceleration cylinder 10 by cutting the acceleration cylinder 10 in the direction in which the acceleration cylinder 10 extends along the cutting line α shown in the cross-sectional view of the base end of the acceleration cylinder 10.
The first conductive rail 11a, the first insulating rail 12a, the second conductive rail 11b, and the second insulating rail 12b are twisted in a parallel spiral shape.
A bald arrow shown in each cross-sectional view indicates the direction of the magnetic field caused by the current flowing through the conductive rails 11a and 11b. As the conductive rails 11a and 11b are twisted, the magnetic field rotates as the acceleration cylinder 10 advances from the proximal end side to the distal end side.
For this reason, the metal armature 20 rotates as the metal armature 20 advances from the proximal end side to the distal end side of the acceleration cylinder 10.

As shown in FIG. 3, an electric field E of E = UB is generated in the axial direction of the metal armature 20 in the metal armature 20 of radius R placed in the magnetic field B rotating at the angular velocity ω. Here, U is the relative speed of the metal armature 20 with respect to the magnetic field.
The electric field E causes a current j = UB / η to flow in the metal armature 20. Here, η is the resistivity of the metal armature 20.
Due to the current j and the Lorentz force F = jB of the rotating magnetic field B, a torque N that rotates the metal armature 20 in the rotating direction of the magnetic field B is generated. This torque N is defined as I when the moment of inertia of the metal armature 20 (assuming that only the metal armature 20 is a flying object) is I.
N = Iω '(1)
It is.
When the radius of the metal armature 20 is R, the length is W, and the mass density is ρ, the moment of inertia I is
I = (πρWR ⁴ ) / 2 (2)
It is.
On the other hand, if the angular velocity ω is P and the velocity of the metal armature 20 is V, the spiral pitch of the conductive rails 11a and 11b is V.
ω = (2πV) / P (3)
It is.
The velocity V of the metal armature 20 is defined as follows. When the mass of the metal armature 20 is M, the inductance gradient of the conductive rails 11a and 11b is L ', and the current flowing through the conductive rails 11a and 11b is J.
MV ′ = (L′ J ² ) / 2 (4)
It is.
If current J is constant, equations (1) and (4) can be easily solved. Substituting the equations (2) and (3), the angular velocity ω and the velocity V are given by the following equations (5) and (6). Here, the depth at which the magnetic field penetrates into the metal armature 20 is λ, the permeability of vacuum is μ, and the elapsed time after energization is t.
ω = (√ {2} μ ² L′ λJ ⁴ t ² ) / (3π ³ ηρ ² R ⁴ W ² P) (5)
V = (L′ J ² t) / (2πR ² Wρ) (6)

As numerical examples, R = 20 mm, W = 40 mm, P = 1 m, metal armature 20 as copper, ρ = 8.93 × 10 ³ kg / m ³ , resistivity η = 2.0 × 10 ⁻⁷ Ωm, λ = 1 mm, the angular velocity ω (converted to the rotational speed per minute) and the velocity V when the current j (= 1 MA) is determined so that the velocity V is 2 km / s with an acceleration length of 2 m are shown in FIG. Shown in
When the acceleration length is 2 m, the angular velocity ω is 40000 rpm in terms of the rotation speed per minute. This is equivalent to the swirl speed of a conventional firearm of the same scale (caliber 40 mm), 30000 rpm.

According to the electromagnetic accelerator 100 of the first embodiment, the following effects can be obtained.
{1} Since the metal armature 20 is accelerated in the axial direction of the acceleration cylinder 10 and simultaneously rotated around the axis, the flying object after being injected into the space from the tip of the acceleration cylinder 10 flies while rotating. , Its flight characteristics become stable.
{2} When the metal armature 20 advances along the acceleration cylinder 10, the metal armature 20 rotates with a slight deviation from the twist of the conductive rails 11a and 11b. For this reason, the supply position of the current to the metal armature 20 moves on the peripheral surface of the metal armature 20, the surface melting of the metal armature 20 by the current is made uniform, and the shape of the metal armature 20 by the current melting Asymmetry can be suppressed, and the flying characteristics of the flying object become stable.
{3} As can be seen from the development of FIG. 2, the conductive rails 11 a and 11 b and the insulating rails 12 a and 12 b are not only alternately arranged in the circumferential direction, but also alternately along the axis of the acceleration cylinder 10. Since it is arranged, the strength distribution of the inner surface of the acceleration cylinder 10 by the metal (conductive rails 11a and 11b) and the insulator (insulating rails 12a and 12b) is averaged, and the reduction of the inner surface is reduced. Does not adversely affect flight characteristics.
{4} Since the inner surface of the accelerating cylinder 10 has a circular cross section and the metal armature 20 is also a metal body having a circular cross section, the portion of the bullet covered with copper from which the shell of a conventional firearm is removed can be used as it is. .

  As shown in FIG. 5, conductive rails 11 a and 11 b configured to have a brush structure by holding the metal fiber 15 with a flange 17 may be used. Reference numeral 16 denotes a power supply electrode.

  As shown in FIG. 6, conductive rails 11 a and 11 b configured to hold a folded metal cloth 18 with a flange 17 may be used.

  For example, a plastic cylindrical body (flying body body) integrated with the metal armature 20 may be used as the flying body.

  The electromagnetic accelerator of the present invention can be used as a rail gun.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration explanatory diagram illustrating an electromagnetic accelerator according to a first embodiment. It is sectional drawing and the expanded view which show the structure of the acceleration cylinder of the electromagnetic accelerator which concerns on Example 1. FIG. It is explanatory drawing for demonstrating the rotation mechanism of the metal armature in the electromagnetic accelerator which concerns on Example 1. FIG. 6 is a graph for explaining a numerical example of an angular velocity and a velocity of a metal armature in the electromagnetic accelerator according to the first embodiment. It is an end view which shows the structure of the acceleration cylinder of the electromagnetic accelerator which concerns on Example 2. FIG. It is an end elevation which shows the structure of the acceleration cylinder of the electromagnetic accelerator which concerns on Example 3. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Pulse power supply 10 Accelerating cylinder 11a 1st conductive rail 11b 2nd conductive rail 12a 1st insulating rail 12b 2nd insulating rail 13 Outer cylinder 15 Metal fiber 16 Feed electrode 17 袴 18 Metal cloth 20 Metal armature 100 Electromagnetic accelerator

Claims (3)

  A pair of conductive rails in parallel spiral shape, a metal armature having a circular cross-sectional outline sandwiched between the conductive rails, and one conductive rail-metal armature fed from one end side of the conductive rail An electromagnetic acceleration device comprising the other conductive rail and a power supply device for passing a large current.   2. The electromagnetic accelerator according to claim 1, wherein the conductive rail is formed of a metal fiber in a brush structure. 2. The electromagnetic accelerator according to claim 1, wherein the conductive rail has a structure in which metal cloths are stacked.

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