Ampoule with starting fuel for igniting liquid rocket propellant components

Abstract: The invention relates to the field of automatic equipment and, in particular, to devices for chemical ignition of LRE propellant components. The ampoule comprises a body, diaphragm units mounted at the body inlet and outlet, each of which is made as a piston made as a single part with a diaphragm. The peripheral part of the diaphragm is fixed in an air-tight manner to the body under a guide element in which the body is mounted. The piston has a stem extending into a guide bush. Furthermore, a device for filling the ampoule with fuel is located in a partition of the body inside the ampoule. A guaranteed cutting of the diaphragm along the entire perimeter and reproduction of hydraulic characteristics for the flow part of the ampoule are achieved in this ampoule design.

Description: Field of the Invention The invention relates to the field of automatic equipment and, in particular, to ampoules with starting fuel to be mounted in the main line of one of the propellant components at the inlet to the mixing head of a combustion chamber or a gas generator for the chemical ignition of propellant components. Background of the Invention Technical solutions are known in which safety and starting valves with rupturable diaphragms are used (US patent No. 3704807, NPC 220-89, published 1972 or GB patent application No. 1138885, NPC F2V, published 1969). In these technical solutions the diaphragm breaks under the effect of pressure of the medium. These constructions do not provide the possibility of ensuring a constant flow section for the medium when the diaphragm breaks. An ampoule with starting fuel for igniting the propellant components of liquid-propellant rocket engines (LRE) is known that comprises a body with an inlet and an outlet, two diaphragm units, the diaphragms of which are air-tight fastened along the periphery in the body from the inlet and outlet sides (the book "Liquid-Propellant Rocket Engine Design and Engineering," edited by G.G. Gakhun, Moscow, Mashinostroenie, 1989, p. 75, Fig. 4.5). In this known ampoule design diaphragm units with rupturable diaphragms are used. In this technical solution, a diaphragm is broken under the effect of medium pressure, and bending the diaphragm (opening the flow section) is carried out due to the pressure drop thereon that is defined, in particular, by the flow rate of the liquid. If the liquid flow rate and, accordingly, the pressure drop on the diaphragm are low, then the diaphragm may first break only partially and then may bend to an arbitrary extent. In view of the fact that after the diaphragm breaks, it or its parts occupy an indefinite and unstable position at different flow rates, such a design does not ensure stable hydraulic characteristics. This is especially important when the ampoules are mounted in parallel main lines of a multi-chamber LRE, where it is necessary to ensure a strictly identical distribution of flow rates along those main lines after the break of diaphragms. Summary of the Invention The object of the invention is to create an ampoule with starting fuel which does not have the aforesaid disadvantages and ensures enhancement of the quality of feeding the starting fuel. An object of the invention is also to create an ampoule with starting fuel which ensures airtightness in respect of the environment during the process of filling it with starting fuel. The engineering result obtained by use of the proposed invention consists of ensuring reliable and uniform breaking of the diaphragm along the perimeter without its detachment or misalignment by the flow of liquid and ensuring stable hydraulic characteristics for the flow part of the ampoule after the break of the diaphragms by high pressure of the medium, but with a low flow rate. The aforesaid result is achieved in an ampoule with starting fuel for igniting the propellant components of an LRE, the ampoule comprising a cylindrical body having an inlet from one side and an outlet from another side, two diaphragm units mounted inside the body from the sides of the inlet and outlet, wherein each of the diaphragm units includes a diaphragm, fixed in an air-tight manner along the periphery to the body with the possibility of the diaphragm being broken by the working medium, in that in accordance with the invention, it comprises means for filling the body with the starting fuel, and each of the diaphragm units comprises a piston, provided with a stem, and a guide bush with attachment means, wherein a diaphragm in each diaphragm unit is made in the form of a ring bridge, the piston is connected to the diaphragm, the piston stem is mounted in the guide bush with the possibility for the piston to move in a longitudinal direction. Wherewith the guide bush is preferably mounted coaxially to the body and is fixed in the body with the aid of ribs. Furthermore, it is preferable that the means for filling the body with the starting fuel be made from two blank flanges - filling and draining, which are mounted in a partition located perpendicular to the longitudinal axis of the body between the diaphragm units in ducts, respectively, filling and draining, which are made in the partition and communicate with the external surface of the body, each blank flange being made in the form of a threaded plug in which a hole is made for communication of the duct with the internal space of the body and a sealing plug provided with a sealing gasket, wherein the sealing plug is mounted in the duct and provided with a nut for fixing it. In one of the embodiments, a spring lock is mounted inside the guide bush, and a ring groove is made on the stem with the possibility of placing the spring lock therein during movement of the piston. Furthermore the stem may be made hollow, wherein its space communicating with the internal space of the body from the face of the stem opposite to the piston, and holes that are located at the piston base connected to the stem are made in the stem wall. And also the thickness of a diaphragm in the place of its connection to the piston is preferably made less than the thickness of the diaphragm in the place of its connection to the body. Brief Description of the Drawings Fig. 1 shows a longitudinal cross-sectional view of an ampoule; Fig. 2 shows a cross-sectional view taken along the lines II-II and II-II (turned) in Fig. 1, made through the filling (draining) blank flange. Description of the Preferred Embodiment An ampoule (Fig. 1) comprises a body 1 with inlet 2 and outlet 3 branch pipes of diaphragm units 4 and 5 mounted inside the body 1, and a means 6 for filling the body with starting fuel. Each of the diaphragm units 4 and 5 comprises a piston that may be made as a single piece with a diaphragm 8 or in which the diaphragm 8 is connected in an airtight manner to its external surface. The piston 7 is mounted in a guide element 9 of the body by means of a slide fit. A peripheral part of the diaphragm 8 is fixed in an airtight manner to the body 1 under the guide element 9. The piston 7 is connected to a stem 10 which may be made cylindrical or in any other form and placed in a guide bush 11. The guide bush 11 by means of ribs 12 is secured to the body 1 of the ampoule. The guide bush 11 has a spring lock 13, made, for example, in the form of a springing ring, and the stem 10 is made with a ring groove 14. When the diaphragm unit goes into action, the spring lock 13 limits movement of the stem 10. Holes 15 are made in the stem 10 to reduce the pressure of the gas from the stagnation zone during the filling of the ampoule. From the side of the inlet 2, the diaphragm 8 is made thin in the form of a ring bridge 16 that may be broken during interaction with the working medium on a diameter D. The diameter D is selected to be somewhat less than the diameter of the piston 7. Where the diaphragm 8 is connected to the piston 7, the former is made with a lesser thickness in order to exclude scratches when the piston 7 moves in the guide element 9 of the body 1. The means 6 for filling the body with starting fuel is introduced into the ampoule. This means is mounted in the partition 17 of the body 1 and consists of two blank flanges - a filling blank flange 18 and a draining blank flange 19, which are mounted respectively in filling 20 and draining 21 ducts. Each of the blank flanges has a threaded plug 22, a sealing plug 23, a sealing gasket 24 and a nut 25. The threaded plug 22 has a flow rate hole 26. Filling the ampoule with the starting fuel is carried out in the following manner. The threaded plugs 22 are screwed onto the assembled ampoule before the nuts 25 and sealing plugs 23 are mounted, but not as far as possible, in such a manner that opening the flow section of the filling 20 and draining 21 ducts through the hole 26 is ensured. The ampoule is filled with the starting propellant, feeding it through the filling duct 20 into the internal space of the body 1 between the diaphragm units 4 and 5, and then through the draining duct for draining. After the process of filling the ampoule is finished, the threaded plugs 22 are screwed as far as possible, after which the starting fuel is drained in front of the threaded plug 22 of the filling blank flange 18 and behind the threaded plug 22 of the draining blank flange 19. After that the sealing plugs 23, sealing gaskets 24 and nuts 25 are set in place. Now the ampoule is ready to be mounted on the rocket engine. It should be noted that a gas cushion is formed in the internal space of the ampoule in the body 1 between the diaphragms 8 as a result of assembling and filling the ampoule. The presence of a gas cushion promotes the assurance of ampoule reliability during its storage and promotes efficient movement of the piston 8 with acceleration when medium pressure is applied to the ampoule inlet. The thickness of the diaphragm 8 in the place of its connection to the piston 7 is selected to be less than the thickness of the diaphragm 8 in the place of its connection to the body 1 with the formation of a ring bridge 16. In addition to excluding scratches, this makes it possible when there is a break of the diaphragm 8 to ensure movement of the piston 7 over a distance A of the guide element 9 of the body with acceleration due to an appropriate selection of a gap between the piston 7 and the guide 9. The device operates in the following manner. When a high-pressure component acts on the diaphragm unit 4 or 5 from the side of the inlet, deformation of the diaphragm 8 takes place with subsequent destruction along the circle D. If the destruction of the diaphragm 8 is not uniform and there is a manifestation of seal failure, the pressure before the piston 7 does not drop because of the presence of a throttling slot formed by the guide element 9 of the body and by the piston 7, the piston continues to move and after complete destruction of the diaphragm 8 it accelerates. Accelerated movement of the piston 7 is ensured due to the presence of a force resulting from a drop of the pressures acting on the surface area defined by the diameter D. In the simplest interpretation, the acceleration is ensured according to the third law of mechanics and is equal to a force divided by the mass of moving parts. The distance "A" over which the piston moves with acceleration and the gap between the piston 7 and the guide element 9 of the body are selected so as to ensure guaranteed cutting of the diaphragm 8 over the entire perimeter, the required delay in opening the flow section of the main line after the diaphragm 8 is cut, and acceleration of the piston 7 which is necessary for actuation of the spring lock 13. The dimensions of the bridges of diaphragms 8 were determined by theoretical calculations and technologically, as a result of which pressure was established which ensured destruction of a bridge of diaphragm 8. Thus, for example, with D = 40 mm and A = 6 mm and the diaphragm made from bronze alloyed with chromium, the axial dimension of the bridge of a membrane 8 is selected to be 0.3±0.02 mm, and the bridge destruction pressure is 50±10 kgf/cm 2 . Then, the stem 10 moving downstream the flow is fixed by the spring lock 13. The hydraulic characteristics of the open diaphragm unit 4 and/or 5 are reproduced with high accuracy, since structural elements having an indefinite location are not to be found in the component flow. Industrial Applicability The proposed ampoule may be most successfully used in the main line of one of the propellant components at the inlet into the mixing head of the combustion chamber or gas generator for chemical ignition of the propellant components.

Claims: An ampoule with starting fuel for igniting the propellant components of an LRE, the ampoule comprising a cylindrical body (1) having an inlet (2) on one side and an outlet (3) on another side, two diaphragm units (4, 5) mounted inside the body (1) from the sides of the inlet (2) and outlet (3), wherein each of the diaphragm units (4, 5) includes a diaphragm (8), fixed in an air-tight manner along a periphery to the body (1) with the possibility of the diaphragm (8) being broken by a working medium, characterized in that the ampoule further comprises a means (6) for filling the body (1) with starting fuel, and each of the diaphragm units (4, 5) comprises a piston (7), provided with a stem (10), and a guide bush (11) with attachment means, wherein a diaphragm (8) in each diaphragm unit (4, 5) is made in the form of a ring bridge (16), the piston (7) is connected to the diaphragm (8), the piston stem (10) is mounted in the guide bush (11) with the possibility for the piston (7) to move in a longitudinal direction. An ampoule according to claim 1, characterized in that the means (6) for filling the body with starting fuel comprises two blank flanges - filling (18) and draining (19), which are mounted in a partition (17) located perpendicular to the longitudinal axis of the body (1) between the diaphragm units (4, 5) in ducts, respectively, filling(20) and draining (21), which are made in the partition (17) and communicate with the external surface of the body (1), each blank flange being made in the form of a threaded plug (22) in which a hole (26) is made for communication of the duct with the internal space of the body (1) and of a sealing plug (23) provided with a sealing gasket (24), the sealing plug (23) being mounted in the duct and provided with a nut (25) for fixing it. An ampoule according claim 1, characterized in that the guide bush (11) is mounted coaxially to the body (1) and is fixed in the body (1) with the aid of ribs (12). An ampoule according to claim 1, characterized in that it additionally comprises a spring lock (13) mounted inside the guide bush (11), and a ring groove (14) is made on the stem (10) with the possibility of placing the spring lock (13) therein during movement of the piston (7). An ampoule according to claim 1, characterized in that the stem (10) is made hollow and its space communicates with the internal space of the body (1) from the face of the stem (10) opposite to the piston (7), and holes (15) that are located at the piston base connected to the stem (10) are made in the stem wall. An ampoule according to claim 1, characterized in that the thickness of a diaphragm (8) at the place of its connection to the piston (7) is selected to be less than the thickness of the diaphragm (8) at the place of its connection to the body (1).

Inventors: BABOSHIN ALEXANDR ANTONOVICH, CHELKIS FELIX JURIEVICH, IVANOV JURY JURIEVICH, KOLOSOVA INNA ALEXANDROVNA, POLUSHIN VALENTIN GEORGIEVICH, ROZANOV BORIS DMITRIEVICH, TJURIN ALEXANDR ANATOLIEVICH, BABOSHIN, ALEXANDR ANTONOVICH, CHELKIS, FELIX JURIEVICH, IVANOV, JURY JURIEVICH, KOLOSOVA, INNA ALEXANDROVNA, POLUSHIN, VALENTIN GEORGIEVICH, ROZANOV, BORIS DMITRIEVICH, TJURIN, ALEXANDR ANATOLIEVICH
Applicants: OTKRYTOE AKTSIONERNOE OBSCHEST, OTKRYTOE AKTSIONERNOE OBSCHESTVO NAUCHNO-PROIZVODSTVENNOE OBIEDINENIE "ENERGOMASH"
Application year: 1999
Main classification: F02K9
IPC codes: F02K9