JPH0455243Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a rocket motor structure in which an igniter is attached to the inner surface of a nozzle skirt via a shear pin.

(Prior art) Regarding the rocket structure mentioned above, the conventional technology is as follows.
INTERNATI ONAL DEFEN SEREVIEW
Grided Missiles 5/1975 (Interavia SA Publishing)
There is something like the one described on page 165,
In the early stages of operation of the rocket motor, it is necessary to blow the rocket motor backwards with good reproducibility the moment its combustion pressure reaches a predetermined value.

Therefore, the applicant proposed a rocket motor with high ignition efficiency as shown in Fig.
112600). In this rocket motor, a heat-resistant insulator is attached inside a spherical motor case 1 and a propellant 2 is directly loaded therein, while the rear of the propellant 2 is opened to form a core hole 3 and a core hole 3 centered on the core hole 3. forming a lumen 5 consisting of radial slots 4;
Igniter 11 to increase the filling rate of propellant 2
are arranged opposite to the cavity bottom 7 of the inner cavity 5, and the ignition nozzle 12
is directed toward the cavity floor 7. This igniter 11 has an auxiliary charge 14 placed in front of an initiator 13 having a starting charge, an ignition case 16 having a main charge 15 in front of it, and a wide-end tubular case 16 placed in front of it. An ignition nozzle 12 is arranged, and the ignition nozzle 12 blows out the combustion gas generated by the main charge 15 at supersonic speed.

The igniter 11 is supported by a disc-shaped igniter holder 30 that fits into the inner surface of the nozzle skirt 20, as shown in FIG. A flange 31 having a tapered surface having the same tendency as the inner wall surface of the nozzle skirt is provided, and the flange 3
1, it is connected to the rocket nozzle 21 via a shear pin 35. Note that 36 is a bushing for reinforcing the driving portion of the shear pin 35, and 22 is a nozzle holder. The igniter holder 30 and the igniter 11 close the rocket nozzle 21 like a so-called nozzle closure.

In such a rocket motor, the combustion gas ejected from the ignition nozzle 12 at supersonic speed is
As shown by the arrow in the figure, it flows along the core hole 3, collides with the cavity bottom 7, reverses itself, and flows out from the nozzle throat 8 without stagnation, so that the thermal energy is uniformly distributed over the entire initial combustion surface of the propellant 2. can be transmitted to propellant 2
The initial combustion surfaces of the two can be ignited almost simultaneously and uniformly. As a result of this ignition, the pressure in the combustion chamber, and thus the total pressure acting on the igniter holder 30, rises rapidly, and the shear pin 35 counteracts this, reaching a yield point and shearing when the total pressure reaches a set value. As a result, the igniter holder 30 is blown away backwards, and the rocket starts thrusting.

(Problem that the invention aims to solve) By the way, in order to ensure the reproducibility of the above-mentioned blow-off motion, such conventional rocket motors require strict control at each stage of design, testing, and manufacturing. The problem was that I had to do it. This is because although the inner surface of the nozzle skirt is usually precisely machined, the igniter holder is generally made of resin or other molded products due to weight constraints, which inevitably leads to limits in accuracy. If a gap is created in the tapered fitting part of the shear pin, bending force as well as shear force will act on the shear pin, and if the gap is created on the combustion chamber side, high temperature combustion gas will flow in from there and heat the shear pin, causing the shear pin to be heated. As a result of the said opposing force of the shear pin being reduced due to the cause,
The igniter holder will be blown away before the combustion chamber pressure reaches the set value (blown-off pressure). Such accuracy problems become more noticeable when the inner surface of the nozzle skirt expands with a curved surface, as in the case of a Prandtl nozzle, for example. If such early blow-off occurs, there is a risk that the igniter in the rocket motor will also become absent at an early stage, or incomplete ignition may occur without the pressure accumulating action being sufficiently performed. Therefore, in order to avoid such phenomena, appropriate safety factors and tolerances are set, and in order to achieve this, strict process control is performed to ensure reproducibility.

Therefore, an object of the present invention is to make it possible to more easily ensure the reproducibility of the blow-off operation.

(Means for Solving the Problems) In order to solve the above problems, a rocket motor according to the present invention has an igniter attached to the inner surface of a nozzle skirt via a shear pin, wherein the shear pin is connected to the nozzle. The skirt is fitted with an inro parallel to the rocket thrust axis formed on the inner surface of the skirt.

(Function) According to the present invention, since the igniter is supported by the fitted part of the inro parallel to the rocket thrust axis, the periphery of this fitted part has a tapered or curved shape. However, it is possible to fit the two regardless of this, and in this case, it is easy to process or form the inro part to ensure accuracy, so it is easy to make the gap between the two small or not at all. becomes. Since the shear pin is driven into this inro part, only a force parallel to the rocket thrust axis, that is, only a simple shear force, acts on the shear pin, and a relative displacement occurs in this joint, causing shear. This state will be maintained until the end, so
The shearing force set on the shear pin is realized as is, and a highly reproducible blow-off action is performed.

(Example) FIG. 1 shows an example of a rocket motor according to the present invention, and the igniter holder 3 shown in FIG.
This is an enlarged view of a portion corresponding to the fitting portion of No. 0. As shown in the figure, the nozzle skirt 25
At the fitting portion of the and igniter holder 40, the nozzle skirt 25 is provided with a female side inro surface 26 parallel to the rocket thrust axis, and the igniter holder 40 is provided with a male side inro surface 41. The shear pin 37 is driven in. Further, the igniter holder 40 includes a flange 42 having a tapered surface having the same tendency as the inner surface of the nozzle skirt 25 in front of the male side inro surface 41. Note that 27 is a nozzle holder, 38 is a sleeve made of a heat-resistant hard alloy such as stainless steel, and 39 is a reinforcing bushing that protects the nozzle skirt 25 from the load acting on the sleeve 38 during the blowing operation.

Next, the manufacturing process of such a fitting part will be explained.

First, the material of the nozzle skirt 25 made of reinforced graphite or abrasion resin is roughly cut, and the bushes 39 (non-perforated) with sleeves 38 are embedded in equiangular relation, and then the inner and outer surfaces of the nozzle skirt 25 are shaped into tapered shapes along with the bushes 39. Finish processing. Next, the female side inro surface 26 is turned. At this time, the outer diameter of the male side inro surface 41 formed on the igniter holder 40 is measured, and the inner diameter of the female side inro surface 41 is adjusted to this. A static fit is desirable. Then, the igniter holder 40 is fitted to form an inro, a through hole for driving the shear pin 37 is bored, and the shear pin 37 is driven into this through hole. After that, a sealer material such as heat-resistant resin is filled and hardened to form the plug 45.
form. Note that the outer circumferential tapered portion of the igniter holder 40 does not require high precision, so the gap 5
0 may occur, but if this gap 50 is filled with a heat-resistant filler, such as a silicone rubber sealer, it is possible to prevent high-temperature combustion gas from flowing into the inro part and thermally protect the shear pin 37. can.

Next, the action will be explained.

When the propellant 2 is ignited by the combustion gas ejected by the igniter 11, the combustion chamber pressure, and therefore the total pressure acting on the igniter holder 40, rises rapidly, and the shear pin 37 counteracts this, bringing the total pressure to the set value. When the yield point is reached, the shear pin 37 is driven into the inro part parallel to the rocket thrust axis, so only a simple shear force acts on the shear pin 37, and the state is not shear. Since the shear resistance is maintained until the end of the shear pin 37, the shear resistance set on the shear pin 37 is achieved as is. and,
After the shear pin 37 is sheared and the igniter holder 40 is blown away, the female side inro surface 26 is in the shadow of the high-temperature, high-speed gas flow, and although the influence of heat is relatively small, the shear pin 37 made of aluminum alloy etc. The remainder is still susceptible to erosion. In this case, since a heat-resistant plug 45 is installed behind the shear pin 37, it is possible to prevent high-temperature combustion gas from blowing through.

(Effect of the invention) As explained above, according to the rocket motor of the invention, the igniter is attached via the shear pin driven into the inro parallel to the rocket thrust axis, so the shear pin only receives a simple shearing force. The design,
This will make it possible to relax the strict controls required at each stage of testing and manufacturing.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view showing an example of the mounting structure of a blow-off board according to the present invention, Fig. 2 is a cross-sectional view showing an example of the configuration of a rocket motor to which the present invention can be applied, and Fig. 3 is a cross-sectional view showing an example of the structure of a rocket motor to which the present invention can be applied. It is a sectional view showing the attachment structure of a flying board. 25... Nozzle skirt, 26... Female side inro surface, 37... Shear pin, 40... Igniter holder, 41... Male side inro surface.

Claims (1)

[Scope of utility model registration request] In a rocket motor in which an igniter is attached to the inner surface of the nozzle skirt via a shear pin, the shear pin is fitted in a state in which it is driven into an inro parallel to the rocket thrust axis formed on the inner surface of the nozzle skirt. Features a rocket motor.