US2684712A - Starting device for space heaters of the pulse jet type - Google Patents

Description

July 27, 1954l Uw. Yl. EJKAMM ETAL 2,684,712

STARTING DEVICE PoR sPAcE HEATERS oF THE PULSE JET TYPE Filed om. 12, 195o Esi Patented July 27, 1954 STARTING DEVICE FOR SPACE HEATERS F THE PULSE JET TYPE Wunibald I. E. Kamm, Willy F. Krautter, and Kurt Staiger, Dayton, Ohio; said Kamm and said Krauter assignors to the United States of America as represented by the Secretary of the Air 'Force Application October 12, 1950, Serial No. 189,876

(Granted under Title 35, U. S. Code (1952),

3 Claims.

The invention described herein may be manufactured and used by or for the United States Government for governmental purposes without payment to us of any royality thereon.

This invention relates to starters for space space heater is started into operation by preheating one spot in the wall of the combustion chamber to incandescence or at least to a temperature in which a premixed charge of fuel and air introduced into the combustion chamber will be fired, thereby setting the heater into resonant operation. The present improvement, resides in the structure of the means provided to introduce a premixed charge of fuel and air into the combustion chamber after the hot spot has been created. Additional means are provided to render the just mentioned fuel-air charge introducing means inoperative after the starting of the pulse type heater.

One of the objects of the invention is therefore the provision of fuel-air charge preparing and introducing means which requires no skilled operator.

Another object is the provision of manually operable means for rendering the fuel-air charge preparing device inoperative as soon as the pulse jet type space heater is set into operation by explosion of the fuel charge.

Another object of the invention is the provision of means for preventing operation of the air inlet means for the fuel-air charge preparing devicer while the spot heating device previously mentioned is manually set into operation.

Referring now to the accompanying drawings:

Fig. 1 is a side elevation, partly in section.

Fig. yf2 is a fragmentary plan view of the valve plate of the pulse jet heater.

Fig. 3 is a section of the valve plate taken on the line 3 3 of Fig. 2.

In Fig. ,1, is a combustion chamber of generally pear-shape, which has an outlet tube Il for the discharge of combustion generated therein, and forming with chamber I0 the pulse jet combustion resonator, the tube II entering the mouth of a flared end air delivery tube I2 which may be of the plain air aspirator and fuel mixing sec. 266) type or of the resonator type as described in the copending application of W. I. E. Kamm et al., Serial No. 129,861-Patent 2,643,107 dated June 23, 1953.

The combustion chamber II) is provided with a carburetor I3 having a suitable air inlet (not shown) and a fuel pipe I4 leading from the fuel tank (not shown). The ratio of fuel to air in the mixture prepared by the carburetor I3 may be regulated by an adjustment member I5. Immediately above the carburetor I3 there is a perforated valve plate I6 which may be of the type shown in Figs. 2 and 3. It consists in general of an upper multiperforated plate 9 and a lower multiperforated plate 8 having registering openings in which hemispherical valve means 5 are displaced upwardly from the perforations in plate 8 and through the separating space l created by the presence of a ring 5. The upward rush of the fuel-air charge prepared in the carburetor I3 into the combustion chamber I0 occurs by reason of the resonant elfects of the shock wave generated in the combustion chamber, the shock wave being reflected at the open end of tube I I as a low pressure wave. The operation of such resonant shock waves is well understood in regard to their action in pulse jet motors. The hemispherical valve means 5 act to seat in and close the perforations in the plate 3 upon Vbeing subjected to an oppositely acting force and explosion in the combustion chamber I0.

The mechanism designed to preheat a spot indicated at I'I on the wall of the combustion chamber comprises an outlet pipe or horn I8 which for intensifying the name may here be provided `with a multiplicity of air inlet ports 9 near its outer end 20, which is preferably Ilared. The pipe I 3 is set in a liquid tight manner by means of a diaphragm 2l forming the bottom of a fuel boiler or fuel heating and vapor pressurizing chamber 22. The boiler 22 is provided with a filler pipe and cap 23 through which it may be filled preferably nearly up to the top with liquid fuel 25, which may be gasoline. A space 24 above the fuel is intended to contain vaporized fuel provided by heating the body of the fuel 25 by means of a burner 2l' of the type which has a needle valve 28 and which is arranged coaxially with and below the pipe I8. A layer of incombustible brous material 29 is provided at the bottom of the lower chamber 36 of the fuel vaporizing boiler 22, the chamber being provided with air inlet openings 22a above the layer 29. This fibrous material, which may be as- 3 bestos, is saturated with fuel by means of a fuel inlet pipe 3l which may derive from the same tanlr from which pipe is is also supplied.

Communication between the space 2d of the boiler 22 and the space 3ft within burner 2l is provided 'by a vapor delivery and superheater pipe 3E which is coiled about the lower end of the outlet pipe lil within the chamber 2li. The upper end of the pipe 32 is open above the liquid in the boiler, whereby to receive under pressure the vaporized fuel held in the space and to deliver it through the diaphragm seal or bottom El to a fuel duct 33 which communicates with the annular fuel space 3d which surrounds the needle 28 of the burner 2l. From the junction point 35 of the pipe 32 with the fuel duct 33, vaporized fuel is then able to flow in two directions, i. e., through the annular space 3a on the one hand to the burner 2l and on the other hand to an operating space or valve chamber 35 containedjn valve housing El, in an outlet from the space 3b a valve 33 of the poppet type is seated, normally to seal off, under the urging of spring 3s, a vaporiaed fuel delivery pipe which extends t a Startinewharse forming or mixing device di, which is pr ferably located on that side of the combustion chamber it which is substantially opposite to the spot il' which is to be heated. Such location allows a short length of tube lill to be used, whereby to avoid heat losses and to provide for directing the starting fuel-air charge with certainty toward the hot spot il on the interior wall of the chamber lil.

actuation of the valve 3S is provided for by a rod d2 to which the poppet valve 33 is coaxially connected. The rod ft2 is provided with a flange 133 for tensioning the coil spring against the valve housing 3l. The rod lil is slidable in a bearing by means of a lug l5 which is tached to the rod and to the short arm of a bell crank Upon the upper surface of the long arm of the bell crankV @Si there is a boss il which arranged to hilaire contact with a striker plate is located on the bottom of a carrier lil of a ring-type air valve eil which is adapted to seat against a bottom surface of an annularly slotted cover 5l of a bowl or body 52 of the air valve ll and close the air iiiet openings therein. The pipe llc; connects into the bowl or body 52 through its bottom, preferably below the center of the ring air valve and its end is directed as a jet nozzle into the mouth 33a of pipe 53. The starting charge inlet pipe 53 connects the covered, annularly slotted cover of the bowl 52 at its center with the interior of the, combustion chamber is, so located relative to the spot il', that the fuelair charge delivered by pipe 53 into the combustion chamber reaclles the hot spot il.

A marinai starting means for the charge forming device il is provided in the form of a push button 5e which is normally urged upwardly by the pressure of the coil spring 55 above a support which is preferably on a higher level than the charge forming device di. rThe button 54 is con nected by a rod 5l with a long arm of a bell crank et whichV in turn is pivoted on a rigid support all at 5S. The shorter arm of the bell cranl: 46 is connected to the lug 45.

To set the device in operation, the pad or liner llt of porous material is first moistened with fuel from the pipe 3l after which the supply of fuel thereto is turned off. The chamber 25 is filled approximately full of fuel leaving the space above the fuel level. This chamber may be filled through the filler pipe 23. Av lighted match is then applied to the saturated porous material 29 through one of the openings 22a in the lower part or chamber 39 of the boiler 22. The flame from the ignited fuel in the wick 23 heats up the fuel 25, vaporizes it and pressurizes boiler 22. The needle 28 is then opened and the flame fed by burner 21 and by air admitted through the openings 22a, now ascends the pipe or horn I3, sucking in additional air for combustion through the holes i3. The essentials of retort combustion are thereby accomplished and a flame hot enough to heat the spot l1 to incandescence is soon produced. The pressure inside the space 2t is checked by means of gauge 58 and the needle valve 28 may be adjusted accordingly. However, the combustion does not become too violent to cause rupture of the container 22 from excessive internal pressure because the strength of the boiler 32 and the lower part of tube I8 is dimensioned for safely holding the highest pressure which is permitted by the rate of gas outflow at burner 2l.

During this time, the poppet valve 3B has remained closed under the urging of the spring 39. When the spot Il on the combustion chamber wall has become hot enough to ignite a fuel-air charge in the combustion chamber id, the push button Sil is manually depressed against the re sistance of the spring 55 until the support 3S is encountered. The rod i'l depresses the longer arm of the bell crank 6, thereby causing the shorter arm to move the lug 5 and consequently the rod l2 to the right, thereby overcoming the resistance of the coil spring 33 and opening the poppet valve 3S. Part of the vaporized fuel descending the vapor delivery and superheater pipe 32 now enters the fuel and air duct 33 and the operating space 36, ascending pipe lil into the charge forming device tl. The ring valve 5i in the charge forming device il is now open due to the action of gravity, since the lug il on the arm of the bell crank i6 has been lowered, permitting the carrier 53 to drop with it. Such action unseats the ring Valve 5d from the circular air inlet slot or seat tl, thereby allowing air to enter and mix with the vaporized fuel projected into pipe 53 from the vaporized fuel supply pipe lill. An aspirating action is produced by the spray of fuel to the pipe 53, thereby entraining air. The button 5s must be held depressed manually during this time until the charge within the combustion chamber l@ becomes ignited by Contact with the hot spot I'I. An explosion then ensues, which closes the openings in the valve plate i8, bac-k pressure in starter pipe 53 also tending to close ring air valve 5i). More explosions follow, alternately closing and opening ring air valve Eil. However, after the first explosion, it is unnecessary to hold the button 54 depressed, so it should be released at this time, the resonant action of the pulse jet motor being able to con tinue by drawing fuel and air through the car buretor i3 into the interior of the combustion chamber le. The charge is exhausted after explosion through the exhaust pipe il. After the button 5t is released, the poppet valve 33 again closes under urgingy of the spring 39; the button 5t is raised under the urging of the spring 55 and the annular Valve 50 positively is closed by the upward push given to the carrier te against the striker plate i8 by the boss fil on the bell crank lili. Ther flame or pressure which may descend the charge inlet pipe 5,3A into the charge forming device 4| has the effect of mak-ing theV seal between the annular air valve4 50 and itsl seat 5l tighter on account of upward uid pressure. It will be seen therefore that the starting mechanism which is the subject matter of our invention, is entirely idle during the operation of the pulse jet heater.

Combustion engineers in possession of this disclosure will be able to make changes and adaptations which will fit our starting device for operation with various kinds of heaters. The invention is therefore not to be limited except by the scope of the appended claims.

What we claim is:

1. A starting device for a pulse jet type space heater having a combustion chamber and a discharge pipe extending therefrom, comprising a fuel heating vaporizing and pressurizing chamber adapted to have a quantity of liquid fuel introduced therein, an upwardly directed central combustion pipe extending through said fuel vaporizing and pressurizing chamber having a heat outlet at its upper end for directing ame and combustion gases to a spot on the exterior of the pulse jet combustion chamber to heat the spot thereon for the ignition of an explosive fuel charge when introduced into the pulse jet combustion chamber against said heated spot, a vaporized fuel jet burner positioned concentrically at the lower and inlet end of said combustion pipe, a fuel heating casing surrounding the mouth of said combustion pipe and said burner having air admission ports formed therein, a wick of non-combustible fibrous material positioned in the fuel heating casing surrounding the burner below the air admission ports, a vaporized fuel superheating and vapor delivery pipe surrounding the combustion pipe within the fuel heating vaporizing and pressurizing chamber with its upper end in communication with the interior of the last mentioned chamber adjacent the top thereof above the normal liquid level of the fuel to be introduced in said last chamber, a vaporized fuel delivery duct connected intermediate its ends to the other end of said superheating and vapor delivery pipe, said fuel delivery duct being connected at one end to said burner, a needle valve for said burner, a charge forming device having a fuel and air mixing chamber and a fuel and air mixture discharge pipe adapted to be connected in communication with the interior of the pulse jet combustion chamber at the side thereof opposite said spot for directing a vaporized fuel and air mixture into the pulse jet combustion chamber toward the heated spot, vaporized fuel injection means positioned in said mixing chamber below said fuel and air mixture discharge pipe and connected to the other end of the fuel delivery duct for injecting vaporized fuel from the fuel heating, vaporizing and pressurizing chamber through the said fuel and air mixing chamber into the fuel and air mixture discharge pipe, poppet valve means in said fuel delivery duct intermediate the vapor delivery pipe connection to said duct and said vaporized fuel injection means, means normally urging said valve means to closed position, manual valve opening means including rod linkage, bell crank lever, and spring opposed means operatively connected thereto for opening said valve means, air inlet valve means in said fuel and air mixing chamber movable to admit air into the fuel and air mixing chamber, and means carried by the valve opening means for closing the air inlet valve means to cut off air supply to the fuel and air mixing chamber simultaneously with the closing of .the valve 6, means, for controlling the supply of vaporized fuel from the fuel heating, vaporizing and pressurizing chamber upon release of the poppet valve opening means.

2. A space heater of the pulse jet type comprising a wall forming a combustion chamber in the shape of a domed inverted cone, an exhaust pipe therefrom, a retort type of spot heater at one side of said combustion chamber adapted to heat a spot on the exterior wall of said chamber about midway up the wall to incandescence, a starting charge injection pipe in fluid communication with the interior of said combustion chamber substantially opposite to the spot to be heated, a fuel and air mixture intake valve plate below Ithe combustion chamber, a carburetor below said valve plate for supplying an explosive fuelair mixture into said combustion chamber, conduit means for supplying fuel to said carburetor, said spot heater including a fuel heating and vaporizing means and a vaporized fuel burner therefor, conduit means from said fuel heating and vaporizing means connected to said burner to deliver vaporized liquid fuel for said spot heater, a fuel and air charge forming device, quick acting vaporized fuel valve means in said conduit means controlling delivery of fuel to said fuel and air charge forming device, spring means normally holding said vaporized fuel valve closed, an air inlet valve in said charge forming device adapted to open under the action of gravity t-o admit air into said fuel and air charge forming device, and manually actuable means adapted to open said vaporized fuel valve and to simultaneously release said air inlet valve whereby to allow it to open, said manually aotuable means including a spring therefor which must be compressed to open the vaporized fuel and air inlet .valve and which will, upon cessation of manual effort, return said vaporized fuel and air inlet valve to its closed posi-tion whereby to seal said charge forming device and cause said combustion chamber to initiate i-ts cycle by drawing into the combustion chamber through said valve plate a fuel-air mixture prepared in said carburetor.

3. In combination, a space heater comprising a wall forming a combustion chamber, an exhaust pipe therefrom, a carburetor for supplying a combustible fuel and air mixture into said combustion chamber, a check valve plate between the carburetor and the said chamber, and a starting device for introducing a fuel and air explosive charge into the combustion chamber and for heating said wall to initiate combustion of said explosive charge in said chamber, said starting device comprising a heater for vaporizing fuel and for heating a spot on the exterior of said wall for the ignition of an explosive fuel-air charge when directed int-o the combustion chamber against the heated spot, said heater comprising a burner including a combustion tube therefrom having a discharge end facing toward said spot for directing Iflame and combustion gases against said spot, a fuel vaporizing chamber heated by said burner .to vaporize the fuel therein, and a fuel supply pipe connecting said fuel vaporizing chamber to said burner, a fuelair charge forming device including means for introducing air therein, a fuel and air charge injection tube connecting the charge forming device and the combustion chamber and arranged to direct said fuel-air charge into said combustion chamber and against the surface of said wall interiorly of said spot, conduit means connected to said fuel vaporizing chamber and said charge forming device for supplying Kthe charge forming device with Vaporized fuel from the fuel vaporizing chamber of said heater, and manually 5 releasable vaporized fuel and air control means for simultaneously cutting off the vaporized fuel and air supply to the charge forming device when released.

References Cited in the le of this patent UNITED STATES PATENTS Number Number Number Name Date Best Aug. 23, 1910 Wise June 4, 1912 Shore Dec. 10, 1929 Masters Dec. 12, 1933 Kemmer et al Sept. 26, 1950 Krauter et al. Dec. 16, 1952 Kamm et a1 June 23, 1953 FOREIGN PATENTS Country Date France Sept. 24, 1919 Switzerland Sept. 30, 1950

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