JPH07189810A - Solid rocket motor - Google Patents

Abstract

PURPOSE:To provide a safe solid rocket motor which is free from danger of a burst even when propellant deteriorates after a long lapse of time from production by preventing the formation of a bottle neck by means of reinforcing ring. CONSTITUTION:A reinforcing ring 8 prevents the increase in an inner pressure of a motor case 1 even when a hollow hole 4 is shrunk because of the deformation of a propellant 3 right after ignition and combustion gas is blocked, so that the motor case 1 is prevented from an explosion.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid rocket motor used in a propulsion device for a flying vehicle.

[0002]

2. Description of the Related Art FIG. 6 is a sectional view showing the structure of a conventional solid rocket motor. In the figure, 1 is a motor case forming an outer shell of the solid rocket motor, and 2 is a rear end portion of the motor case 1. The nozzle 3 is a propellant filled inside the motor case 1, and the propellant 3 is formed into a hollow cylindrical shape having a hollow hole 4 in the center. An igniter 5 is attached to the front end of the motor case 1 to ignite the propellant 3.

Next, the operation will be described with reference to FIG. When the igniter 5 is ignited by, for example, an electric signal, the explosive contained in the igniter 5 is ignited, and a high-pressure combustion flame 6 is ejected toward the inner surface of the hollow hole 4. The propellant 3 starts to burn from the inner surface by being exposed to the combustion flame 6, and the generated high-pressure combustion gas passes through the hollow hole 4 and is jetted backward from the nozzle 2 to obtain a propulsive force. The propellant 3 continues to burn toward the outside, and the diameter of the hollow hole 4 also increases accordingly.

[0004]

Although the conventional solid rocket motor is constructed as described above, the propellant 3 is usually used.
Is a mixture of gunpowder and resin and is molded, and the material is usually deteriorated after a long time has passed after the manufacture. In general, the widely used butadiene resin is 10
It is known that after a lapse of more than a year, the elasticity decreases sharply, and when an external force is applied, it is likely to deform significantly. The operation when the solid rocket motor that has passed such a long time is ignited will be described with reference to FIG. Propellant 3 is combustion flame 6
Since combustion starts from the front end portion that is first exposed to, the pressure in the hollow hole 4 also rises first at the front end portion. As a result, it is known that the propellant 3 is intensively compressed at its front end as shown in FIG. 8, and the pushed propellant 3 is swollen at its rear end and is deformed like a wave. As a result, the hollow hole 4 becomes narrower at the rear end so that the narrow hole 7 is formed. Since the bottleneck 7 blocks the ejection of the combustion gas, the internal pressure of the motor case 1 becomes abnormally high in front of the bottleneck 7. This is an instantaneous phenomenon immediately after ignition, and when the propellant 3 burns and is consumed, the bottleneck 7 expands and the damming effect disappears, and the internal pressure returns to normal in a short time. However, in order to make the solid rocket motor as light as possible, the motor case 1 is often made extremely thin, and the pressure resistance is often insufficient. Therefore, even if it is momentary, if the internal pressure becomes abnormally high, the motor case may not be able to endure and may burst.
Therefore, when using a solid rocket motor that has been in use for a long time after manufacturing, it is necessary to know how far the elasticity of the propellant has deteriorated.
It is not completely understood at present, and it is not easy to accurately predict the degree of elasticity reduction. In addition, it is difficult to actually measure how much the elasticity of the propellant has deteriorated without destroying the already assembled solid rocket motor. After all, by selecting a sample from a solid rocket motor that has actually passed for a long time, disassembling it, and measuring the degree of elasticity decrease, it is only possible to consider that the solid rocket motors other than the sample have also decreased to the same degree. It was a practical means. However, since there are individual differences in the deterioration of the propellant, it cannot be said that this is a very reliable method, and in order to determine the usage limit, it was necessary to allow a margin much larger than the actual measurement results of the sample. As described above, the conventional solid rocket motor is
Not only does it not withstand use for a long time after manufacture, but its limit is not clearly known, so there is a problem that even a product that can withstand use is unusable more than necessary.

The present invention has been made to solve the above problems, and an object thereof is to obtain a safe solid rocket motor in which the motor case does not burst even if the elasticity of the propellant decreases. .

[0006]

The solid rocket motor according to the present invention comprises a reinforcing ring in the hollow hole of the propellant.

Further, the reinforcing ring is provided with a receiving seat for holding it stably.

Further, the reinforcing ring is made of, for example, phenol resin,
It is made of a material that is easily decomposed by heat.

Further, an opening is provided on the outer peripheral surface of the reinforcing ring.

Further, the reinforcing ring does not come into close contact with the inner surface of the hollow hole, but has a gap.

Further, an extension portion extends from the igniter, and a reinforcing ring is held at the tip of the extension portion.

Further, the reinforcing ring is made of an elastic material such as spring steel, and is adapted to adhere to the inner surface of the hollow hole by its own elasticity.

Further, the reinforcing ring is made, for example, in a foldable manner so that the outer shape can be changed.

[0014]

The solid rocket motor according to the present invention prevents the propellant from deforming immediately after ignition to form a bottleneck.
The reinforcing ring prevents the internal pressure from rising.

Further, since the reinforcing ring is provided with the receiving seat for stably holding it, the nozzle is not blocked even if the reinforcing ring is blown away by the jet flow of the combustion gas.

Further, since the reinforcing ring is made of a material which is easily decomposed by heat, it burns out in a short time after ignition of the solid rocket motor and is discharged together with the jet of combustion gas so that the nozzle is not blocked. To do.

Further, since the opening is provided on the outer peripheral surface of the reinforcing ring, the propellant acts on the portion covered with the reinforcing ring without delay.

Further, since the reinforcing ring does not adhere to the inner surface of the hollow hole and a gap is provided, the propellant acts on the portion covered with the reinforcing ring without delay.

Further, since the extension portion extends from the igniter and the reinforcing ring is held at the tip of the extension portion, the reinforcing ring acts so as to be stable even if it does not adhere to the inner surface of the hollow hole.

Further, since the reinforcing ring is made of an elastic material and is brought into close contact with the inner surface of the hollow hole by its own elasticity, the reinforcing ring acts so as to be stable without adhering to the propellant.

Further, since the outer shape of the reinforcing ring is made variable, even if the inner diameter of the hollow hole is larger than the opening of the motor case, the reinforcing ring can be mounted at a predetermined position through the opening.

[0022]

【Example】

Example 1. FIG. 1 is a cross-sectional view showing the structure of an embodiment of the present invention. In the figure, a ring-shaped reinforcing ring 8 that fits exactly to the inner surface of a hollow hole 4 is bonded.
The reinforcing ring 8 is made of a material that is harder than the propellant 3 and does not easily deform, such as iron. Also, this reinforcing ring 8
In the case of the conventional solid rocket motor, is bonded to the position where the bottleneck 7 is formed as shown in FIG.

When the solid rocket motor shown in FIG. 1 is ignited, the propellant tends to be deformed as shown in FIG. 8, but the propellant is blocked by the reinforcing ring 8 and cannot bulge inward, and the bottleneck 7 is not formed. . Therefore, the combustion gas is not stopped and the internal pressure does not rise abnormally immediately after ignition.
Although the reinforcing ring 8 is exposed to the high temperature combustion gas and softens, the reinforcing ring 8 has no time to transfer the heat to the inside for a very short time immediately after ignition and can prevent the deformation of the propellant. Alternatively, the reinforcing ring 8 may be made of a material that does not soften even at high temperatures, such as ceramic.

Example 2. Even if the reinforcing ring 8 is made of a heat-resistant material in the first embodiment, as the propellant 3 is consumed, the hollow hole 4 expands, and the reinforcing ring 8 moves freely due to the disturbance of the jet flow. As a result, the reinforcing ring 8 may move to a position that covers the throat portion 9, and even if it is not pushed into the throat portion 9, there is a risk of damaging the jet flow. In the embodiment shown in FIG. 2, a receiving seat 10 is provided in front of the throat portion 9 so that the reinforcing ring 8 just fits therein. When the propellant 3 in the portion in contact with the reinforcing ring 8 burns and the reinforcing ring 8 becomes free, the reinforcing ring 8 is pushed by the jet flow and fits into the receiving seat 10, and thereafter, it stabilizes at that position. Therefore,
There is no fear that the reinforcing ring 8 will cover the throat portion 9 and stop the jet flow.

Example 3. In the embodiment of FIG. 1, the reinforcing ring 8 cannot withstand high temperature and is thermally decomposed from the surface like phenol resin, for example, but the heat is not transmitted to the inside for a very short time and the original shape is maintained. It can be made of such materials. As a result, not only the internal pressure rise immediately after ignition is prevented, but thereafter, the reinforcing ring 8 is rapidly pyrolyzed and discharged together with the combustion gas from the nozzle 2, and there is no fear of stopping the jet flow.

Example 4. When the solid rocket motor is ignited in the embodiment of FIG. 1, the combustion flame 6 of FIG. 7 does not hit the surface 11 of the propellant in contact with the reinforcing ring 8, and the ignition is delayed accordingly. If the width of the reinforcing ring 8 is narrow, the combustion proceeds from before and after the reinforcing ring 8 to catch up the delay, and finally, there is no fear that the combustion characteristics of the solid rocket motor will be significantly disturbed. However, if the solid rocket motor becomes long, if the narrow reinforcing ring 8 is attached at only one location, the propellant 3 will swell before and after the reinforcing ring 8 and a similar bottleneck 7 will be created. In order to prevent this, it is conceivable to arrange a plurality of reinforcing rings 8 or use a reinforcing ring 8 having a wide width in the vertical direction. As a result, the area of the surface 11 covered with the reinforcing ring 8 increases, and even if the other portion burns out, this portion will remain burned to the end, and uniform burning characteristics may not be obtained. FIG. 3 is an external view showing only the reinforcing ring of the embodiment for preventing this,
A large number of window-shaped openings 12 are opened on the outer peripheral surface of the reinforcing ring 8. Since the combustion flame 6 shown in FIG. 7 hits the surface 11 of the propellant through the opening 12, the area where ignition is delayed is extremely small, and the width of the reinforcing ring 8 can be widened.
It is easy to obtain uniform combustion characteristics.

Example 5. Depending on the nature of the propellant, even if Example 4 is used, the disturbance of the combustion characteristics due to a slight ignition delay may not be negligible. In the embodiment shown in FIG. 4, the reinforcing ring 8 is not in close contact with the hollow hole 4 and is separated by keeping the gap 12. Therefore, since the reinforcing ring 8 cannot be bonded to the propellant 3, the extending portion 13 is protruded rearward from the igniter 5 and the reinforcing ring 8 is held at the tip thereof via the support rod 14. Therefore, since the surface 11 is not covered with the reinforcing ring 8 and is completely exposed, uniform combustion characteristics can be obtained without delay in ignition.

Example 6. In Example 5, the reinforcing ring 8
The extension portion 13 and the support rod 14 are used to provide the gap 12 between the propellant 3 and the propellant 3. However, even if the gap 12 is unnecessary, the same shape should be used to hold the reinforcing ring 8 securely. You can The adhesive strength is greatly affected by variations in the properties of the adhesive and the skill of the operator, and it is not always easy to obtain uniform strength. By mechanically supporting the extension portion 13 and the support rod 14, the reinforcing ring 8 can be held with a stable strength without variation, and even after the propellant 3 is burned, the reinforcing ring 8 is blown off by the jet flow. There is no fear of blocking the throat part.

Example 7. In Examples 1 to 6, the reinforcing ring 8 is made to have a predetermined size from the beginning, but in reality, the hollow holes 4 do not always have the same size, and often have variations. It is not easy to make a large number of reinforcing rings 8 of different sizes in accordance with this, and when the reinforcing ring 8 is to be mounted later on a solid rocket motor that has already been completed, the dimensions of the hollow holes 4 can only be roughly known. There are also many. FIG. 5 shows the appearance of only the reinforcing ring of the embodiment in which the outer diameter of the reinforcing ring can be adjusted. The reinforcing ring 8 is a plate made of a material having a high elasticity, for example, spring steel, which is wound in a spiral shape, and the outer diameter is reduced when the force is further applied to cause the outer diameter to decrease. To return to. Therefore, the reinforcing ring 8 can be elastically adhered to the inner surface of the hollow hole 4 even if the diameter of the hollow hole 4 is not constant, and the position thereof can be held only by the elastic force without any particular adhesion or the like. You can

Example 8. When the reinforcing ring 8 is not mounted from the beginning and the reinforcing ring 8 is mounted later on the already completed solid rocket motor, it may be difficult to insert the reinforcing ring 8 depending on the size of each part. For example, in FIG. 1, whether it is inserted from the rear through the throat portion 9 or the igniter 5 is removed and inserted from the front,
Since the reinforcing ring 8 has a larger diameter, it cannot be inserted from the outside as it is. Therefore, for example, if a reinforcing ring 8 whose outer diameter can be adjusted as shown in FIG. 5 is used, the throat portion 9 can be passed through in a state where the outer diameter is reduced by tightly winding it and the outer diameter is increased in the hollow hole 4 for mounting. You can

[0031]

As described above, the solid rocket motor according to the present invention is constructed so that the reinforcing ring prevents the propellant from deforming immediately after ignition to form a bottleneck so that the internal pressure does not rise. Therefore, there is an effect that the motor case does not burst even after a long time has passed since the manufacture and can be used safely.

Further, since the reinforcing ring is provided with the receiving seat for holding it stably, there is an effect that the nozzle is not blocked even if the reinforcing ring is blown away by the jet flow of the combustion gas. .

Further, since the reinforcing ring is made of a material which is easily decomposed by heat, it is burnt out in a short time after ignition of the solid rocket motor and is discharged together with the jet of combustion gas.
The effect is that the nozzle is not blocked.

Further, since the opening is provided on the outer peripheral surface of the reinforcing ring, the propellant can ignite without delay even in the portion covered with the reinforcing ring, and uniform combustion characteristics can be obtained. is there.

Since the reinforcing ring does not adhere to the inner surface of the hollow hole and is provided with a gap, the propellant ignites without delay even in the portion covered with the reinforcing ring to obtain uniform combustion characteristics. There is an effect that is.

Further, since the extension portion extends from the igniter and the reinforcing ring is held at the end of the extended portion, there is an effect that the reinforcing ring can be stably held even if it does not adhere to the inner surface of the hollow hole.

Further, since the reinforcing ring is made of an elastic material and is brought into close contact with the inner surface of the hollow hole by its own elasticity, there is an effect that the reinforcing ring is stable without being adhered to the propellant.

Further, since the outer shape of the reinforcing ring is variable, the reinforcing ring can be easily attached to the already completed solid rocket motor later.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a solid rocket motor according to an embodiment of the present invention as seen obliquely from the front.

FIG. 2 is a sectional view of a solid rocket motor according to another embodiment of the present invention as seen from the side.

FIG. 3 is an external view of a reinforcing ring of a solid rocket motor according to still another embodiment of the present invention as seen obliquely from the front.

FIG. 4 is a cross-sectional view of a solid rocket motor according to still another embodiment of the present invention as seen obliquely from the front.

FIG. 5 is an external view of a reinforcing ring of a solid rocket motor according to still another embodiment of the present invention as seen obliquely from the front.

FIG. 6 is a sectional view of a conventional solid rocket motor seen obliquely from the front.

FIG. 7 is a cross-sectional view of a state in which a conventional solid rocket motor is ignited as seen obliquely from the front.

FIG. 8 is a cross-sectional view of the state immediately after the conventional solid rocket motor is ignited, as viewed obliquely from the front.

[Explanation of symbols]

 1 Motor Case 2 Nozzle 3 Propellant 4 Hollow Hole 5 Igniter 6 Combustion Flame 7 Bottleneck 8 Reinforcement Ring 9 Throat 10 Receiving Seat 11 Surface 12 Clearance 13 Extension 14 Support Bar

Claims (5)

[Claims] 1. A motor case is filled with a propellant, a hollow hole is formed in the propellant, and the propellant is burned from the inner surface side of the hollow hole toward the outside to generate the propellant. A solid rocket motor in which combustion gas is ejected from a nozzle provided at the rear end of the motor case, wherein a reinforcing ring is provided inside the hollow hole and at a position close to the nozzle. . 2. The solid rocket motor according to claim 1, wherein a receiving seat for holding the reinforcing ring is provided behind the reinforcing ring. 3. The solid rocket motor according to claim 1, wherein one or more openings are provided on the outer peripheral surface of the reinforcing ring. 4. The solid rocket motor according to claim 1, wherein a gap is provided between the outer peripheral surface of the reinforcing ring and the inner surface of the hollow hole of the propellant. 5. The solid rocket motor according to claim 1, wherein an igniter for igniting the propellant has an extension, and the extension supports the reinforcing ring.