JP2017211118A - Laser ignition device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser ignition device smaller than conventional ones and enable quick ignition.SOLUTION: A laser ignition device includes: a laser oscillation device 2 configured to generate laser light 2a; a lens 4 configured to condense the laser light 2a on a focal point F; main igniter powder 10 positioned forward on an anti-lens side with respect to the focal point F; an ignition unit 6; and a second clearance 16 extending forward from the ignition unit 6 and reaching the main igniter powder 10. The ignition unit 6 has first igniter powder 6a positioned at the focal point F, and second igniter powder 6b opposite to the first igniter powder 6a with a first clearance 14 held therebetween, and positioned between the first igniter powder 6a and the main igniter powder 10.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a laser ignition device that ignites with laser light.

As an igniter for igniting a propellant of a solid rocket, one using a gunpowder is common. In order to simplify the ignition device, an ignition device using a laser beam has been studied.
For example, Patent Literature 1 and Patent Literature 2 disclose an ignition device using laser light.

JP-A-8-303301 JP 2013-57446 A

  The ignition device of Patent Document 1 ignites the ignition agent by pressing the exit end of the optical fiber against the ignition agent.

The energy per unit area necessary for igniting the ignition agent is determined in advance. However, no matter how small the diameter of the optical fiber is, there is a limit. Even if the optical fiber has a small diameter, the energy of the laser light is dispersed in the diameter.
Therefore, in order to achieve the energy required for ignition (laser output per unit area) over the entire exit end of the optical fiber, a laser beam with a large output is required, and a large-scale laser oscillation device is required. To do. Therefore, it has been difficult to reduce the size or weight of the ignition device of Patent Document 1.

  Patent Document 2 discloses an ignition device including a lens that condenses laser light. By providing the lens, the laser beam can be condensed at one point. For this reason, since the energy density of the ignition device can be increased by condensing, even a laser beam weaker than the ignition device of Patent Document 1 can exceed the energy per unit area required for ignition and can be ignited.

  However, since the ignition device of Patent Document 2 condenses laser light at one point, the ignition agent to be ignited is limited to a very narrow range. Since the igniting agent of such an igniter gradually burns and spreads gradually from its small ignition point, it takes a lot of time for combustion to become full-scale. Therefore, the ignition device of Patent Document 2 has a feature that ignition is slow.

  The present invention has been developed to solve the above-described problems. That is, an object of the present invention is to provide a laser ignition device that is smaller than a conventional ignition device and can be ignited quickly.

According to the present invention, a laser oscillation device for generating laser light;
A lens that focuses the laser beam on a focal point;
A main ignition agent that is located in front of the focal point and is on the opposite side of the lens and generates combustion gas by combustion, and a laser ignition device comprising:
Ignition having a first igniter located at the focal point, and a second igniter located opposite to the first igniter and the main igniter opposite to the first igniter with a first gap therebetween Unit,
And a second gap extending forward from the ignition unit and reaching the main igniting agent.

  Further, the first gap is a distance that reaches the first igniting agent or the second igniting agent opposed to each other by the type of fire scattered from the burning first igniting agent or the second igniting agent.

  The first igniter or the second igniter is amorphous boron nitrate.

In addition, a case for storing the ignition unit and the main ignition powder is provided,
The case has a daylighting hole provided on the optical path of the laser beam at the rear end,
A transmission window material that transmits the laser light and hermetically closes the daylighting hole;
A discharge hole provided at a front end portion for discharging the combustion gas to the outside of the case,
The first igniter is provided on the front surface of the transmission window material.

  Further, the transmission window member is provided by being fitted into a recess provided on the front surface of the rear wall surface of the case.

  Moreover, the fixing device which fixes the said 2nd ignition powder to a rear-end part, and fixes the said main ignition powder to a front-end part is provided.

  According to the apparatus of the present invention described above, since the lens for condensing the laser beam is provided, the first ignition agent can be ignited even if the laser ignition device is a small one having a small laser beam output. .

  When the laser ignition device of the present invention has the first gap, the first igniting agent bounces and scatters in all directions in the first gap when the pressure rises due to combustion. As a result, sparks and sparks (hereinafter referred to as fire type) with fire adhere to a wide area of the rear surface of the second igniting agent, so that the spark type is less than when the second igniting agent is placed in contact with the first igniting agent. The area of the attached second igniter is increased.

In addition, the laser ignition device of the present invention includes a second gap extending between the main ignition agent and the ignition unit, the main ignition agent being disposed forwardly from the second ignition agent.
With this configuration, the combustion gas can be brought into contact with more explosive surfaces by flowing the high-temperature and high-speed combustion gas in a narrow space called the second gap. Thereby, even if there are less main ignition agents than the ignition agent of the conventional ignition device, the main ignition agent can be promptly ignited.

  Accordingly, the first igniting agent and the second igniting agent are arranged to face each other across the first gap, and the ignition unit and the main igniting agent are connected by the second gap, so that the amount of the igniting agent is smaller than that of the conventional ignition device. Even if it exists, it can ignite promptly.

  Therefore, the laser ignition device of the present invention can be configured smaller than the conventional ignition device, and can be ignited quickly.

It is sectional drawing of the laser ignition device of this invention. It is explanatory drawing of the flow of the combustion gas in the laser ignition device of this invention. 3 is a graph comparing ignition times of Experimental Example 1 and Comparative Example 1.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the common part in each figure, and the overlapping description is abbreviate | omitted.

FIG. 1 is a cross-sectional view of a laser ignition device 1 of the present invention.
The laser ignition device 1 of the present invention includes a laser oscillation device 2, a lens 4, a main ignition agent 10, an ignition unit 6, a second gap 16, a case 12, and a fixture 18. Moreover, the ignition unit 6 has the 1st ignition powder 6a and the 2nd ignition powder 6b which oppose.
In the following description, the optical path between the first igniting agent 6a and the laser beam 2a is defined as a focal point F. Further, the laser oscillation device side (the lens side from the focal point F) in the optical path of the laser light 2a is defined as the rear side, and the opposite side (the anti-lens side from the focal point F) is defined as the front side.

  The laser oscillation device 2 is a device that generates laser light 2a. For example, it is preferable that an optical fiber 2b is connected to the laser oscillation device 2, and the laser light 2a is output from the front end portion (exit end portion) of the optical fiber 2b. However, the present invention is not limited to this, and the laser beam 2 a may be irradiated directly from the laser oscillation device 2 toward the lens 4.

The lens 4 is provided between the exit end of the optical fiber 2b and the first ignition agent 6a, and condenses the laser light 2a at the focal point F.
If the laser light 2a can be condensed on the front surface of the first ignition powder 6a, the number of the lenses 4 may be one.

  Or as shown in FIG. 1, the lens 4 may be provided combining 2 or more. For example, in the case of FIG. 1, the rear lens 4 converts the laser light 2a emitted from the exit end of the optical fiber 2b into parallel light (parallel laser light 2a). The front lens 4 collects the parallel light at the focal point F. Since the parallel light travels in parallel, even if the distance between the front lens 4 and the rear lens 4 changes, the width orthogonal to the optical path of the laser light 2a does not change.

  Therefore, with this configuration, the distance between the front lens 4 and the rear lens 4 can be freely set. For example, the case 12 can be installed at a position away from the laser oscillation device 2 by setting the distance between the front lens 4 and the rear lens 4 to be long. Thereby, it can prevent that the laser oscillation apparatus 2 is exposed to the high heat | fever by combustion of ignition powder, and fails.

  The main ignition powder 10 is located in front of the focal point F (on the right side in FIG. 1), and generates combustion gas by burning. Of the igniting agents (the main igniting agent 10 and the first igniting agent 6a and the second igniting agent 6b described later) provided in the laser ignition device 1 of the present invention, the main igniting agent 10 generates the most combustion gas. The main ignition powder 10 is preferably, for example, pellet-shaped boron nitrate. However, the present invention is not limited to this, and the main igniting agent 10 may be another igniting agent. For example, the main ignition powder 10 may be a mixture of aluminum powder, ammonium perchlorate, and a resin (binder) for hardening them. Boron nitrate is a mixture of crystalline boron, nitrate and binder.

The case 12 houses the ignition unit 6 and the main igniting agent 10, and has a daylighting hole 12a, a transmission window member 12b, and a discharge hole 12c. The case 12 preferably has a pressure resistant structure. For example, in the case of the example of FIG. 1, the case 12 has a packing portion 12d (for example, an O-ring) having a storage portion having a front end wall (hereinafter referred to as a front wall surface) and a side wall and a rear end wall (hereinafter referred to as a rear wall surface). ).
However, the configuration of the case 12 may be other.
The case 12 is preferably made of, for example, a titanium alloy, but may be made of other materials.

  FIG. 2 is an explanatory diagram of the flow of combustion gas in the laser ignition device 1 of the present invention. In this figure, the movement of the gunpowder and sparks ignited is indicated by solid arrows, and the flow of combustion gas is indicated by broken arrows.

  The discharge hole 12c is a through hole provided in the front end portion of the case 12 (the front wall surface in the example of FIG. 2). The combustion gas flowing forward (right side in FIG. 2) through the second gap 16 is discharged to the outside of the case 12 through the discharge hole 12c.

  The daylighting hole 12 a is a through hole provided on the rear wall surface of the case 12 on the optical path of the laser beam 2 a.

The transmission window member 12b is a member that transmits the laser light 2a and hermetically closes the daylighting hole 12a. The transmission window material 12b may be made of, for example, acrylic, quartz glass, or sapphire glass. However, the present invention is not limited thereto, and other materials may be used as long as they have heat resistance, laser beam 2a transparency, and pressure resistance.
By providing the transmission window member 12b in the daylighting hole 12a, the laser beam 2a can be passed inside the case 12 while maintaining the airtightness of the rear surface of the case 12.

As shown in FIG. 2, the transmissive window member 12 b is preferably fitted from the front (right side in FIG. 2) into a recess 12 e provided on the front surface of the rear wall surface of the case 12. Accordingly, when the internal pressure of the case 12 rises due to the generation of combustion gas, the transmission window member 12b is pressed against the rear wall surface of the case 12 toward the rear.
Therefore, the combustion gas is prevented from leaking from the daylighting hole 12a, and the airtightness of the daylighting hole 12a is maintained.

  With this configuration, even if the front and rear two holes (lighting hole 12a and discharge hole 12c) are opened in the case 12, the combustion gas is released only from the discharge hole 12c. Therefore, the combustion gas is released only in front of the case 12.

The fixture 18 is made of a material that does not burn, holds the second igniter 6b and the main igniter 10, and fixes their positions. For example, the fixture 18 may be made of bakelite. Further, as shown in FIG. 2, the fixture 18 may form the shape of the second gap 16.
For example, the fixture 18 may fix the second igniting agent 6b at the rear end portion and the main igniting agent 10 at the front end portion. In this case, the main ignition powder 10 may be fixed to the side surface or the front surface of the fixture 18.

  The ignition unit 6 has a first igniting agent 6a and a second igniting agent 6b facing each other. In the following description, the first igniting agent 6a, the second igniting agent 6b, and the main igniting agent 10 are collectively referred to as an igniting agent.

  In the ignition unit 6, in order to make the spread of the flame faster, the explosive having a quick spread of the flame is used for the first igniter 6a and the second igniter 6b. The first igniter 6a and the second igniter 6b generate high-temperature and high-speed combustion gas by combustion.

  The 1st ignition powder 6a is provided in the front surface of the permeation | transmission window material 12b. The rear surface of the first igniting agent 6a is located at the focal point F or near the focal point F (hereinafter simply referred to as “focal point F”). For example, the first ignition agent 6 a may be applied to the front surface of the transmission window member 12 b of the case 12.

  The second igniting agent 6 b faces the first igniting agent 6 a with the first gap 14 interposed therebetween, and is positioned between the first igniting agent 6 a and the main igniting agent 10. The second igniter 6b is preferably provided with a larger amount of explosive than the first igniter 6a.

Moreover, it is preferable that the area of the rear surface of the 2nd ignition powder 6b is provided more widely than the area of the front surface of the 1st ignition powder 6a.
Thereby, the fire type scattered in all directions from the first igniter 6a can be efficiently received on the rear surface of the second igniter 6b.

  The first igniting agent 6a or the second igniting agent 6b is preferably, for example, amorphous boron nitrate. However, the present invention is not limited thereto, and the first igniting agent 6a or the second igniting agent 6b may be powdery or granular boron nitrate, aluminum powder, ammonium perchlorate, and a mixture of binders for solidifying them. Note that the amorphous boron nitrate is a mixture of amorphous boron, nitrate and binder.

  The first gap 14 is a distance at which the sparks scattered from the burning first igniter 6a or second igniter 6b reach the first igniter 6a or second igniter 6b facing each other. For example, the first gap 14 may be a distance of about 0.5 to 3 mm. Alternatively, the distance of the first gap 14 may be larger as long as the scattered fire type can adhere to the opposing first igniter 6a or second igniter 6b.

The second gap 16 extends forward from the ignition unit 6, reaches the main igniting agent 10, and communicates with the outside of the case 12 through the discharge hole 12 c of the case 12. The second gap 16 is connected to the first gap 14.
For example, in the example of FIG. 1, the main ignition powder 10 is exposed to the second gap 16 and held on the side surface of the fixture 18. Further, for example, the second gap 16 may be provided between the case 12, the ignition unit 6, and the main ignition agent 10 as shown in FIG. 1. However, the present invention is not limited to this, and the second gap 16 may constitute another flow path.

The second gap 16 is preferably provided as narrow as possible so that the combustion gas generated by the combustion of the first igniter 6a or the second igniter 6b can pass through. For example, the distance of the second gap 16 may be about 2 mm (for example, 0.5 to 3 mm).
Thus, even if the amount of the first igniting agent 6a, the second igniting agent 6b, and the main igniting agent 10 is smaller than that of the conventional igniter, the pressure of the combustion gas can be quickly increased. The speed at which the combustion gas turns is proportional to the pressure of the combustion gas, and the faster the pressure rise rate, the faster the speed at which the combustion gas turns. Therefore, by configuring the second gap 16 to be narrow, it is possible to ignite quickly even if the amount of the ignition agent is smaller than that of the conventional ignition device.

Moreover, the 2nd clearance gap 16 may be provided so that it may become narrow from the back toward the front, as shown in FIG. In the case of the laser ignition device 1 of FIG. 2, the fixture 18 has a shape in which the cross-sectional area orthogonal to the optical path gradually increases as it goes forward. Thereby, the 2nd clearance gap 16 of FIG. 2 becomes narrow as it goes ahead. Alternatively, the second gap 16 may be formed by the inner surface shape of the case 12 in addition to the outer surface shape of the fixture 18.
With this configuration, the flow rate of the combustion gas generated in the ignition unit 6 increases as it goes forward.

  Hereinafter, the present invention will be specifically described based on each experimental example. In addition, this invention is not restrict | limited to the following content.

  In Experimental Example 1, the ignition time including the main igniter 10 was measured using the above-described laser ignition device 1 of the present invention. The output of the laser beam 2a of the laser oscillation device 2 of Experimental Example 1 was 1W. Of the igniting agents used in Experimental Example 1, the first igniting agent 6a is amorphous boron nitrate, and the second igniting agent 6b and main igniting agent 10 are a mixture of crystalline boron, nitrate and resin (binder). Met.

  As Comparative Example 1, the ignition time was measured using a laser ignition device that differs from the laser ignition device 1 of the present invention described above only in that it does not have the first ignition agent 6a. The laser condensing position at that time was the second ignition agent 6b. The laser beam output of the laser oscillation device of Comparative Example 1 was also 1 W. Of the igniting agents used in Comparative Example 1, the second igniting agent 6b and the main igniting agent 10 were a mixture of crystalline boron, nitrate, and a binder.

  FIG. 3 is a graph comparing the ignition times of Experimental Example 1 and Comparative Example 1. This figure represents the relationship between the presence / absence of the first ignition agent 6a and the ignition time. In this figure, the vertical axis shows the ignition time in a non-dimensional manner. The bar graph on the left side of this figure shows Comparative Example 1, and the bar graph on the right side shows Experimental Example 1.

  In this figure, it is made dimensionless with the ignition time of Comparative Example 1 as a reference. That is, the value of Experimental Example 1 in this figure is a value obtained by dividing the actual measured ignition time of Experimental Example 1 by the actual measured ignition time of Comparative Example 1.

  As shown in this figure, Experimental Example 1 ignited in about half the time (0.4 times to 0.6 times) of Comparative Example 1. Thereby, it turns out that the laser ignition device 1 (Experimental example 1) of the present invention can be ignited at about twice the speed of the laser ignition device without the first ignition agent 6a by having the first ignition agent 6a. It was.

  According to the apparatus of the present invention described above, since the lens 4 for condensing the laser beam 2a is provided, even if the laser ignition device 1 is a small one with a small output of the laser beam 2a, the first ignition agent 6a is used. Can be ignited.

  In the laser ignition device 1 of the present invention, the first igniting agent 6 a and the second igniting agent 6 b are explosives whose burning spread speed is fast, and the first igniting agent 6 a is disposed at the focal point F of the lens 4. Since the first gap 14 is provided between the first igniting agent 6a and the second igniting agent 6b, when the first igniting agent 6a is ignited, the pressure of the first igniting agent 6a increases, and the ignited explosive is blown off. Scattered. Since the 2nd ignition powder 6b is arrange | positioned in the position which opposes the 1st ignition powder 6a, the scattered powder reaches the 2nd ignition powder 6b and makes it ignite. Since the ignition unit 6 and the main igniter 10 are connected by the second gap 16, the combustion gas generated between the first igniter 6a and the second igniter 6b passes through the second gap 16 and forward (FIG. 2). Then, it spreads to the right) and ignites the main igniter 10.

That is, the laser igniter 1 of the present invention has the first gap 14 so that the first igniting agent 6a bounces and scatters in all directions in the first gap when the pressure rises due to combustion. As a result, sparks such as sparks and sparks are attached over a wide area on the rear surface of the second igniting agent 6b, so that the second igniting agent 6b is in contact with the first igniting agent 6a. The area of the second igniting agent 6b with is increased.
Therefore, since the laser ignition device 1 of the present invention can burn the second igniting agent 6b in a wider range, the combustion of the second igniting agent 6b can be started in earnest early.

  In addition, the laser ignition device 1 of the present invention includes the second gap 16 extending between the main ignition powder 10 and the ignition unit 6, the main ignition powder 10 being disposed forwardly from the second ignition powder 6 b. With this configuration, the combustion gas can be brought into contact with the surface of more explosives by flowing the high-temperature and high-speed combustion gas through the narrow space of the second gap 16. Thereby, even if the main ignition charge 10 is less than the ignition charge of the conventional ignition device, the main ignition charge 10 can be quickly ignited.

Therefore, the first igniting agent 6a and the second igniting agent 6b are arranged to face each other with the first gap 14 interposed therebetween, and the ignition unit 6 and the main igniting agent 10 are connected by the second gap 16, thereby making the conventional ignition device. Even if the amount of the igniting agent is smaller, it can be ignited promptly. Therefore, it can be configured smaller than the conventional ignition device, and the ignitability can be improved. Further, since the laser ignition device 1 of the present invention can be formed in a small size, it can be made lighter than a conventional ignition device.
Thereby, the laser ignition device 1 of the present invention can apply a small, light, and space-saving ignition system to the upper stage motor of the space rocket.

  Note that the present invention is not limited to the above-described embodiment, and it is needless to say that various modifications can be made without departing from the gist of the present invention.

1 Laser ignition device,
2 laser oscillator, 2a laser light, 2b optical fiber,
4 lenses,
6 ignition unit, 6a first igniter, 6b second igniter,
10 Main ignition,
12 case, 12a daylighting hole, 12b transmission window material,
12c discharge hole, 12d packing, 12e depression,
14 1st clearance, 16 2nd clearance, 18 Fixing tool,
F Focus

Claims (6)

A laser oscillation device for generating laser light;
A lens that focuses the laser beam on a focal point;
A main ignition agent that is located in front of the focal point and is on the opposite side of the lens and generates combustion gas by combustion, and a laser ignition device comprising:
Ignition having a first igniter located at the focal point, and a second igniter located opposite to the first igniter and the main igniter opposite to the first igniter with a first gap therebetween Unit,
And a second gap extending forward from the ignition unit and reaching the main ignition agent.   2. The first clearance according to claim 1, wherein the first gap is a distance that reaches the first igniting agent or the second igniting agent opposed to each other by the type of fire scattered from the first igniting agent or the second igniting agent that burns. Laser ignition device.   The laser igniter according to claim 1 or 2, wherein the first igniter or the second igniter is amorphous boron nitrate. A case for storing the ignition unit and the main ignition powder;
The case has a daylighting hole provided on the optical path of the laser beam at the rear end,
A transmission window material that transmits the laser light and hermetically closes the daylighting hole;
A discharge hole provided at a front end portion for discharging the combustion gas to the outside of the case,
The laser ignition device according to any one of claims 1 to 3, wherein the first ignition agent is provided on a front surface of the transmission window member.   The laser igniter according to claim 4, wherein the transmission window member is provided by being fitted in a recess provided in a front surface of a rear wall surface of the case.   The laser ignition device according to any one of claims 1 to 5, further comprising a fixture that fixes the second ignition powder to a rear end portion and fixes the main ignition powder to a front end portion.

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