US2897649A

US2897649A - Igniter

Info

Publication number: US2897649A
Application number: US595800A
Authority: US
Inventors: Reddy Robert
Original assignee: Individual
Current assignee: Individual
Priority date: 1956-07-03
Filing date: 1956-07-03
Publication date: 1959-08-04
Anticipated expiration: 1976-08-04

Description

All@ 45 1959 R. REDDYl 2,897,649

Y IGNITER Filed July 3. 1956 2 Sheets-Sheet 1 R. REDDY Aug. 4, 1959 IGNITER Filed July :5, 1956 2 Sheets-Sheet 2 INVENTOR.

M jf HTTEA/FYS United States Patent() 2,891,649 IG1-1rrERY Robert Reddy, Pasadena, Calif., assignor to the United States of America as represented by the Secretary of the Air Force Application July s, 1956, serial No.' 595,800

' 6 claims. (c1. so-'3932) This invention relates to an igniter for a combustion apparatus and, more particularly, to a multistage igniter primarily for use with hypergolic propellants.

Combustion chambers of rocket engines, for example, require a flame having high heat intensity for igniting the fuel propellant. lf a ame of the required high intensity 2,897,649 Patented Ang. 4, 1.959

y having'pistons 22 'and 23 movable therein, respectively were produced rapidly, inthe igniter, there would be y,

danger of an explosion in theA igniter. If an attempt were made to create such a large ame suddenly in the combustion chamber, there' also exists the possibility that the fuel in the combustion chamber would not ignite and an expensive procedure would result in ultimately igniting the fuel by creating a flame ofv high heat intensity in the combustion chamber. The igniter of the present invention creates the desired llame of suicient intensity by igniting the propellants gradually rather than rapidly.

An object of the present invention is to provide an A nozzle 24 is disposed on the end of the piston 22, which is .shown in cross 'section in Fig. 2. It will be understood that'the movement ofthe parts of the piston y22 and the cylinder 20 also `applies to the cylinder 21 and the piston 23, which are not shown in cross section. A passage 25 extends through the center of the piston 22 and a plurality of radially extending passages 26 is in connection with the passage 25. As is readily seen, the radial passages 26 are spaced along the passage 25.

As the pressure in the primary ignition chamber 11 increases due to the combustion therein, the pressure is transmitted into the secondary ignition chamber 12`and against the faces of the

pistons

22 and 23, which are in communication with the secondary ignition chamber 12.

' This pressure increase results in the piston 22 moving igniter that produces a substantial ignitiony ame therein at a gradual rate. d

Another object of this invention is to provide an igniter that projects its llame into a Vcombustion chamberwhen the flame has a suicient intensity to ignite the fuel in the combustion chamber.

Other objects will be readily preceived from therfollowing description. l

This invention relates to an igniter having two ignition chambers in communication with each other. Puel is initially supplied to the smaller of the'.two ignition chambers by suitable'means for ignition therein. As the pressure resulting from the' combustion in the smaller chamber in transmitted to the larger ignition chamber, fuel is supplied to the larger chamber by suitable means in response to this pressure increase in the second chamber. This fuel, of course, is ignited in the larger chamber.

The attached drawings illustrate preferred embodiments of the invention, in which against the force of a spring 27, which is disposed between the'cylinder 20 and the piston 22. As the piston 22 moves outwardly'against the force of the spring 27, the outermost of the passages V26 communicates with an annular port or groove 28 in the wall of the cylinder 20. The annular port 28A is supplied with Ithe fuel propellant through a tube 29 that is connected to the fuel source (not shown). It will be understood that an annular port inthe wall of the cylinder 21 isY connected to an oxidizer source (not shown). VV.As the outermost ofthe passages 26 communicates with the annular port 28, the fuel passes therethrough into the passage 25 and through the nozzle 24 into' the `secondary ignition chamber 12. Similarly, the' oxidize'r passes through the outermost of the radial passages in lpiston 23 1and through the central passage and nozzle into the Vsecondary ignition chamber 12. EIt will be understood 'that the size of the radial passages in the piston'23 is in proportion to the size of the radial passages 26 in the piston 22 `in the same ratio as desired between the mix# ture of oxidizer and fuel to produce combustion. This Fig. 1 is a side elevational view of the igniter'of the present invention;

Fig. 2 is a sectional view taken along thev line 2-2 Fig. 1; and

' Fig. 3 is a sectional view showing a modification ofthe igniter of Figs. 1 and 2.

' VReferring to the drawings and particularly to Figs. 1

and 2, there is shown an igniter housing 10 including-a primary ignition chamber 11 and a secondary ignition chamber 12 in communication with eachother. A fuel, such as a hypergolic propellant,is,supplied to the primary ignition chamber 11 through a tube 14. The fuelv propelprimary ignition'chamber 11., .The-heating element 16 has f depends 9,1; thefgrrce ofthe Sarina .33 ,t

mixture ratio, of course, depends on the oxidizer and the fuel employed. Y'

lThe heat generated i'n the primary ignition chamber V11 is transmitted into the secondary chamber 12 where the fuel entering the secondary chamber 12 through the nozzle 2 4is ignited. This, of course, further increases the pres; sure exerted against the face of the piston 22 to move the piston 22 further outwardly whereby more of the passages 26 communicate with the annular port 28 to increase the supply of fuel through the rnozzle 24 to the secondary ignition chamber 12. lit will be understood that the' piston 23 s likewise exposed to the pressure from the chamber 12 and supplies the desired proportional quantity of the oxidizer through its nozzle (not shown).

The housing 10 has ra passage 30, which connects the secondary ignition chamber 12 with a combustion chamber 31 of a rocket engine, for example. A poppet valve 32 controls the passage 30 to prevent communication between the secondary ignition chamber 12` and :the combustion chamber 31 until a predetermined pressure exists Within the secondary ignition chamber12. The existence of this 4predetermined pressure within the secondary ignition chamber 12 indicates a ame has been created suicient to ignite the propellants in the combustion chamber 31. -The poppet valve 32 is held inits closed position by a spring 33 acting against a flanged member v34, which is secured to one end of a rod 35 on `the other end of which the poppet valve 32 is formed. The amountof force required to open the poppet valve 32 i. Considering the operation of the embodiment of the present invention shown in Figs. l and 2, the fuel is sup? plied through the tube 14 and the oxidizer through the tube 15-to the primary ignition chamber 11 for combustion therein. The heating element 16- heats `both propellants vpi'iorfto their deliveryinto the'primaify ignition chamber 11... Since the quantity is small andy the propellants'are heated; the propellants easiiypignife'nypergoncaty." As p the primary ignition chamber 11- communicates with-both the secondary ignition chan'ib'erl 12 and 'the

pistons

22 and 23, the pressure 'created by the combustion in the primary chamber 11 is transmitted to the secondary charnber 12 and the

pistons

22 and 23'. sthispresSure inereas, the

pistons

22 and 23` are 'forced outwardly Vin their respective cylindersf20 vand"2'1"to allow'commnication between the annular port and at least one of the radial passages. This supplies the fuel and oxidizer propellants to the secondary chamber 12;'where they are ignited readily as they enter the secondary ignition cham ber 12 due to the heat therein.

The additional combustion in the secondary ignition Ychamber 12 creates additional pressure whereby the

pistons

22 and 23 move to the full extent of their travel and permit communication between theY annular groove and all of the radial passages tosupply a larger'amount of the propellants through the nozzles tothe secondary ignition chamber 12. The increasing'combustion resulting from the larger supply of propellants tothe secohdary lignition chamber 12 causes a further pressureincrease in the secondary ignition chamberjthis furtherv pressure increase in the secondary ignition chamber moves lthe poppet valve 32 against the force of thespring 33 to open the passage and the flame emerges from the igniter housing 10 into the combustion chamber v31 of the rocket .engine to ignite the propellants therein. It will be understood that the ow of propellants to the igniter is stopped upon ignition within the combustion chamber 31 of the rocket engine; thisv reduces the pressurein the secondary ignition chamber 12l and the spring 33' automatically moves the poppet valve 32 to close the passage 30 and prepare the igniter for a new cycle.A

A modification of the embodiment of Figs. l and 2 is shown inFig. 3 where both propellants are suppliedito the secondary ignition chamber through a single piston and cylinder rather than through separate pistons and cylinders. The igniter housing 10' has both a primary ignition chamber 11 and a secondary ignition chamber 12' communicating with each other. Avtube 14' supplies a fuel propellant to the primary ignition chamber 11' while a tube 15 supplies an oxidizer propellant to the primary ignition chamber 11'. .Both'of. these tubes are yWrapped around :an electrical heating element 16.l

which is disposed within the igniter housing 10' to heat the propellants prior to their delivery tothe primary ignition chamber 11. The heating element 16' haslwires 17 and 18 connected to a suitable source of electric power (not shown). The heating -element 16 and the tubes 14 and 15 are insulated by suitable insulating v oxidizer source (not shown), alsoexte'nds through the 1' cylinder 40. A plurality of slanting passages 43 connects the passage 42 and a plurality of slanting passages 46 connects the passage 45 with the annular portion of the cylinder 40 in which the annular piston 41 moves.

`A' spring 44, which is disposed between the wall of the cylinder 40 and the pistonA 41, urges the piston141 to the position shown inFig. Srwhere the"

v passages

43 and 46 are closed by the piston 41,. As the pressure in the secondary ignition chamber 12 increases due to the ignition of the propellants in the primary chamber 11', the pressure forces the piston 41 against the spring 44 to open some of the passages 43. This permits fuel propellant to flow through the passage 42 and the passages 43 and oxidizer propellant to iiow through the passage 45 and the passages 46 into the secondary ignition chamber 12 where they are ignited by the heat resulting from the initial combustion in the primary ignition chamber 11. This creates a pressure increase in the secondary ignition chamber that nally results in allk of the

passages

43 and 46 being opened to 'further increase the supply of fuel and oxidizer propellants to the secondary chamber 12. This additional pressure increase in the chamber 12 acts against the poppet valve 32' to overcome the force of the spring 33' to open the passage 30' and allow the flame, which was created in the secondary ignition chamber 12', to enter the combustion chamber 31. It will be noted that the

passages

43 and 46 are slanted to direct the propellants in a jet type manner into the secondary chamber 12. The size of the passages 46 is proportioned with respect to the size of thepassages 43 in the same ratio as thedesired mixture of oxidizer to fuel required to produce combustion.

, Thus, the operation of the modification of Fig. 3 is substantially the same as, thatjdescribed vwith respect to Figs. 1 and 2 with the differencebeing that a single piston and cylinder are employed to supply both propellants to the secondaryl ignition chamber rather than two cylinders `and pistons. It also will be -noted that the nozzles of the modification of Figs. 1 and 2 have been eliminated by

theslanting passages

43 and 46. Y

l While the description refers to the employment-of a fuel propellant and an oxidizer propellant being heated to produce the ignition, it will be understood that a spark could be relied upon to vignite the fuel in the primary ignition chamber and a spark also couldrbe used in the secondary chamber if the fuel employed were not of the type ignited from the heat caused by the ignition in the primary chamber. The only requirement is that some type of means be employed for creating a gradual rate of ignition of the fuel in the igniter housing and the flame not be released therefrom until it has sufficient intensity to ignite the fuel within the combustion chamber .to which the igniter housing is connected.

An advantage of the present invention is that it prevents an explosion in the combustion chamber until a satisfactory flame is available for igniti-ng the fuel therein. A further advantage of this invention is that it creates a substantial dame but ignites the fuel gradually rather than rapidly. Still another advantage of this invention is that it is less expensive for starting'combustion in a combustion chamber since less fuelis wasted if there is a failure in the igniter housingvof the presentinvention rather thanin a device having the starter ignition in the combustion chamber per se.

For purposes of exempliication, particular embodi ,ments of the invention have been shown and described according to the bestpresent understanding thereof. However, it will be apparent that changes and modiiications in the arrangement and construction of the parts thereof may be resorted to without departing from the true spirit and scope of the invention.

l. In combination, a combustionchamber, an igniter forthe combustion chamber including Aa first ignition chamber and a second Vignition chamber in communica- -tioni with. eachl other, means to admit fuel to the rst yignition. chamber, means to ignite the Vfuel in the rst ignition chamber, means tosupp'ly fuel to the' second ignition chamber in response toY a pressure increase in the second ignition chamber `for ignition in the second chamber comprising integrally formed fuel and oxidizer 'passage' meansand integrallygrooved piston meanshav ing a forward set of proportionally related, radially extending grooves in communication between saidifuel and oxidizer passage means and said second chamber to form a combustible mixture therein acted on by the heat generated in said first chamber and a plurality of rearward, radially extending grooves integrally formed in said piston means to progressively increase the supply of combustible mixture formed in said second chamber on movement of said piston means in accordance with the increase of pressure of the combustion in said first chamber, and means responsive to a further pressure increase in the second chamber to direct the flame in the second chamber to the combustion chamber.

2. An igniter including a first ignition chamber, a second ignition chamber in communication with the first ignition chamber, means to admit fuel to the first ignition chamber, means to ignite the fuel in the first ignition chamber, land piston means normally spring urged lto closed position movable in response to a pressure increase in the second ignition chamber to a progressively open position to initially supply a minimum of fuel and oxidizer to the second ignition chamber for ignition :in the second chamber and having radially extending conduits formed therein in progressive communication with said -second chamber to progressively increase the mixture of fuel and oxidizer therein in accordance with the increase of pressure in said first chamber.

3. In combination, -a combustion chamber, an igniter for the combustion chamber including a first ignition chamber and a second ignition chamber in communication with each other, means lto admit fuel to the rst ignition ch-amber, means to ignite the fuel in the first ignition chamber, piston means movable in response to a pressure increase in the second ignition chamber to supply fuel to the second ignition chamber for ignition therein, said piston means increasing ythe supply of fuel as the pressure in the second ignition chamber increases, a passage connecting the second ignition chamber with the combustion chamber, and valve means to control the passage, said valve means being responsive to a predetermined pressure in the ysecond ignition chamber to open the passage to allow the name to enter the combustion chamber, said piston means comprising a cylinder positioned adjacent one end of said second ignition chamber, an annular piston mounted within said cylinder normally urged to its closed position with one face thereof in open communication with the interior yof said second ignition chamber, Ian outer fuel `supply conduit and an inner oxidizer supply conduit incorporated in said cylinder, and a plurality of fuel-oxidizer conduits integrally formed in said piston in progressive open communication with said fuel and oxidizer supply conduits on progressive movement of said piston by a predetermined pressure within said second ignition chamber.

4. In combination, a combustion chamber, an igniter for :the combustion chamber including a first ignition chamber land a second ignition chamber in communication with each other, means to admit fuel to the rst ignition chamber, means to ignite the-fuel in the first ignition chamber, means to supply fuel to the second ignition chamber for ignition therein, means to control the supply means in accordance with the pressure in the second ignition chamber whereby a pressure increase in the second ignition chamber increases the supply of fuel thereto comprising at least one resil-iently mounted, annularly disposed piston normally held in closed position with one face thereof communicating with the interior of said second ignition chamber and acted on by a predetermined pressure therein to move to open position, said piston having fluid passages in communication with said supply means to transfer fuel into said second ignition chamber when said piston is moved to open position, a passage connecting the second ignition chamber with the combustion chamber, and poppet valve means to control the passage including an elongated valve member integrally `formed on said valve means and having spring urged means on the other end :thereof normally resisting the pressure within said second ignition chamber until the flame formed therein effects .a further pressure increase above a preset minimum, said Valve means being responsive to a predetermined pressure in the second ignition chamber to open the passage to allow the flame to enter the combustion chamber.

5. An igniter including Ia main housing having a first ignition chamber, a second ignition chamber in communication with the rst ignition chamber, means to admit fuel to the first ignition chamber, means to ignite the fuel in the first ignition chamber, means to supply fuel to the second ignition Ichamber for ignition therein, and means to control the supply means in -accordance with the pressure in the second ignition chamber whereby a pressure increase in the second ignition chamber increases the supply of fuel thereto comprising a cylinder incorporated within said main housing adjacent to said second ignition chamber having 4an outer annular passage extending therethrough and adaptable for connection to a source of fuel propellant and an inner annular passage extending therethrough and adaptable for connection to -a source of oxidizer and having a plurality of fluid passages, respectively, connecting said outer and inner annular passages with an annular portion of said cylinder interionly thereof, and an annular piston movably mounted within said annular portion adjacent to one end of said plurality of fluid passages normally closing said passages in one position thereof and -gradually movable under a predetermined pressure within said second ignition chamber to a second, open position to progressively open said huid ,passages and effect increasing iiow of fuel and oXidizer therethrough into said second ignition chamber in accordance with the pressure increase within said second chamber.

6. An igniter including a first ignition chamber, a second ignition chamber in communication with the lirst ignition chamber, means to admit fuel to the first ignition chamber, means to ignite Ithe fuel in the first ignition chamber, piston means having nozzle means in communication with said second ignition chamber and having .a plurality tof spaced grooves movable therewith in response to' a pressure increase in the secondignition chamber to open communication between a supply -of fuel land ioxidizer :and said second ignition chamber for ignition `in the second chamber, said piston means progressively increasing the number of grooves formed therein in communication between the supply of fuel and oxidizer in said second chamber to increase the supply of fuel and oxidizer delivered thereto as the pressure in the first ignition chamber increases, a passage connecting the second ignition chamber with a main combustion 'chamber or the like, and valve means to control the flow of -ame through Ithe passage, said valve means being movable to its 'open position only on response to a pressure above a predetermined pressure in the second chamber to lopen the passage to allow la flame of suicient heat intensity to enter the combustion chamber.

References Cited in the le of this patent UNITED STATES PATENTS 2,683,963 Chandler July 20, 1954 2,707,479 rDhornann et lal May 3, 1955 2,775,865 Welch Jan. 1, 1957 2,847,826 Howes f.- Aug. 19, 1958 FOREIGN PATENTS 503,766 Germany July 26, 1930 719,946 Great Britain Dec. 8, 1954