US944776A - Propulsion of submarine boats. - Google Patents

Description

C. DEL PROPOSTO.

PROPULSIONOP SUBMARINE BOATS.l

APPLICATION FILED 00T.5, 1907.

944,776'. Patented Dec. 28,1909.

` '2 SHEETS-SHEET 2.

, l '-xNv'ENTQR, vs. CSfDIODELPROPOSTQ r wwwm- CEsIDIo :DEL PRoPos'ro, or ROME, ITALY.

PROPILSION OF SUBMARINE BOATS.

Specification of Letters Patent.

Application filed October 5, 190'?. Sera1 No. 396,358.

To all whom it may conce-m:

Be it known that I, CiisiDIo DEL PROPOSTO, a subject of the King of Italy, residing at Rome, Italy, have invented certain new and useful Improvements in Propulsion of Submarine Boats; and I do hereby declare the following to be a lfull, clear, and exact description of the same.

This invention has for its object to iniprove the means of production of energy for the propulsion of submergible or submarine 'boats of every kind, propelled under Water by compressed air (without batteries of electric accrunulators) and toincrease their radius lof action under water while maintaining on board an energetic ventilation and a comfortable temperature. For the propulsion of submarine boats of this type while under water,'the compressed air, has been until today utilized in one of the two followingmanners: (l) The compressed air stored up in suitable reservoirs, is used to4 feed a compressed air-motor which drives the propeller shafts and then discharges outsidegthe boat. (9.) The compressed air is utilized merely to support the combustion in the cylinders of an internal combustion engine. In the former case is utilized the i mechanical energy stored up in the compressed air, in the latter case energy is produced by burning in the cylinders of the motor the oxygen conta-ined in the compressed air. Q

By adopting the system hereinafter set out the same compressed air can be utilized successively in the two ways mentioned above,

Aand consequently, increases considerably the total work which can be produced by means of a given quantity of air at a certain pressure. and, therefore, all other conditions being equal, it increases in the same` rate the radius of action of the boat under Water.

On the annexed drawing, 'Figure l shows schematically b y way of example the arrangement of the di'erent parts .l of, the motive apparatus, and Fig. 2 a longitudinal section of a submarine boat according to the present invention.

In said drawing, -1-2-3-4- represent the four cylinders of an vexplosion engine by means of which the boat-while navi,-

gating' at the'surface is propelled and air is stored up through a compressor `-6f driven by the propel,ler shaft into [suitable reservoirs f-9.

Patented Dec. 28, i909..

and further to drive a subsidiary compressor 6.- which brings the compressed air coming out from the 'cylinder -1'- and -2--, of the motor to the normall pressure of the reservoirs; thus ther compression will be made in two successive steps and in two distinct engines. The air compressed in the cylinders -1-, 2'- reaches the coinpressor 6 through the pipes 13" and 21- respectively. By such arrangement the power and also the weight and encuinbraiice of the independent compressor canfbe reduced considerably.

During the navigation under water the energy. for the propulsion of the boat will be supplied both by a compressed air motor and by the internal' combustion motor, which, under water is kept ruiming just as in the open air. The airY escaping from the compressed air motor, is discharged into the inside ofthe boat, circulates through saine and ventilates it and then is aspired by the' internal combustion motor, and discharged,

as combustion gases outside the boat. A

separate engine may'beemployed as a compressed air motor; but in order to diminish the weight and encumbrance of the machinery on board,-itlis better to use, for this purpose,

either the same compressor 6 used for navigation (provided that its construction allows itto be reversed) or one or more cylinders-for instance the cylinder 1-,- or -1 and *2f of the internal combustion motor,

(Wliich in -tliisfcase, should be polycylin- .storing the compressed air during the surface case, therefore, during the navigation under l of the compressed air motor; therefore it is water, the cylinders of the internal combustion motor work partly in the usual way, and partly as compressed air motors, so that the compressed air which is brought to a suitable pressure by means of a reducing valve l0 passing through the subsidiary reservoir 8 reaches irst the cylinder 1 which acts as a compressed air motor or the cylinders 1 and` Q when the valve 23 is open, is then discharged through the tube 12 in the inside of the boat. and is aspired by the other cylinders of the internal combustion motor through the tribe M by means of the pipes l5-7L, and discharged outside the boat at 16sthrough the pipes 13 and the exhaust box 11 From the foregoing it appears clearly that in the aforesaid system the same air is util- ',ized firstly to produce energy in the compressed air motor, by its expansive force,

and then, after having ventilated the boat, it is utilized in combination with an appropriate fuel to feed an internal combustion engine and thus is enabled to develop a. second time thermal energy for the propulsion. T his system therefore reduces considerably the total consumption of air per H. P. transmitted to the propeller shafts. With the same object in view, viz. to reduce the consumption of air 4for each H. P. developed it is advisable to use on board a compressed air motor which may be fed at the highest possible initial pressure, because, as is well known, the consumption of air per effective H. P. in compressed air motors diminishes when the admission pressure increases. It is also advisable to select for this purpose an 'internal combustion engine in which the consumption of air per effect-ive H. P. be the smallest possible; therefore it is also to be preferred a motor with a high final pressure (Diesel type for instance) and the average pressure of which (average given by the diagram of the indicator) be the highest possible. Such a motor possesses the advantage not only of consumingT the smallest possible quantity of air, but also of being less influenced by the counter pressure in the discharge phase, which counter pressure, in a submerged boat,- depends upon the depth of the immersion and tends to diminish the power which the motor can develop. lt is also known that the air consumption of a compressed air motor can be reduced by heating previously the compressed air to a v convenient temperature; it is knownv as Well that said consumption can be still reduced considerably if the compressed air is previously saturated with steam at the temperature of admission.. Moreover the result of these two operationsis to increase the temperature of the air at the escape and thus vto prevent the formation of ice in the cylinders convenient to adopt both in the submarine boats of the aforesaid system.

In the compressed air engines working in the open air, the heat necessary for the pre lilninary heating and for the saturation of the compressed air is obtained by the combustion of an appropriate fuel but this must be avoided as much as possible on board of submarine boats because the combustion of the fuel results finally in an additional consumption of air. lt is possible to reduce or even to avoid completely' any air consumption for this purpose: (l) by utilizing as much as possible in performing said operations the heat still contained in the escape of the internal combustion motor;

hy increasing if necessary, the heat contained in said gases, .by burning in their midst a convenient fuel; and this is always possible because the gases escaping from the internal combustion engine contain unavoidabl)v a considerable percentage of lmlmrncd free o.\' gen, which, under suitable conditions can support. the combustion of a certain quantity of fuel. Practically the heating andthe satu ation of the compressed air will be performed by circulating the compressed air within a closed vessel ll in the. ordinary apparatus provided therefor, with the cxception however that said apparatus have to be heated in the manner mentioned above. that is in the exhaustbox by means ofthe exhaust gases ,escaping through the pipes 13 from the cylinders 2 3- 1 a By employing the above mentioned process for the utilization of the compressed air, coming out from the reservoir Q and reaching the cylinders 1 and Q through 10 8 11 l5 13 2l logether with the heating and saturation by heat of the exhaust gases, in the exhaust box ll it is possible to reduce the consumption of air per efi'egtive H. P. developed on the propeller shaft downto limits heretofore unknown. And in fact, all other conditions being equal, the weightl of the machinery on board becomes much less than the weight of the machinery for submarine boats propelled under waterby a battery of electrical accumulatore, or even by compressed air utilized in the manner now generally in use.

The total efficiency of the compressed air utilized as a motivefpower is reduced: by the losses of energy in the compressor, (2) by the losses of energy in the compressed air motor, and also by the fact that the pressure in the reservoirs is.. generally higher than the allowable initial pressure in the compressed air motor, so that the use of a reducing valve 10 is necessary, while the preliminary heating and saturation -of the com ressed'air by means of the exhaust gases o the explosion engine is an excellent method of utilization of the heat stored sion, there may Aiugthe indications of the barometer,

in said gases and tends to enhance the total efficiency mentioned above. Byconveniently regulating the work of the Various parts olf the whole plant it is possible to increasethe total efficiency of the compressed air used in this way almost up to unity.

In the foregoing the fuel consumption has never been considered, because, during the navigation under water it is very small in comparison with the consumption-of air and because the diiiiculty of storing the necessary fuel is beyond comparison less than that of, Y stormgthe compressed air.

The barometrical pressure 1n a submarine boat of the type considered mustremain almost constant, during the navigation under Water and not much different from the ordinary atmospheric pressure and independent from the depth of immersion of theboat. This condition is'evidently required by the welfare of the crew and also for the satisfactory Working of the explosion engine, because the air pressure in the machinery room is an important factor in the working of the engines and it contributes in determining the pressure developed in the cylinders, and iniuences the combustion as Well as the extreme temperatures of the lcycle; therefore considerable variations of pressure in the interior of the boat are not ad# missible.4 The barometric pressure inside the boat under Water Will remaln statlonary provided-that the quantity of exhaust air escaping from all the compressed air engines (on board, besides the compressed air motor which produces the energy for the propulbe other compressed air engines for vvarious services, the exhaust of which is discharged also inside the boats) be equal to the quantity of air aspirated by the explosion engine, with the combustion gases, boat. The indications of a barometer permit therefore to ascertain Whether the aforesaid correspondence is maintained and show how to eventually regulate the pressure.

vShould the vpressure beginto differ from the normal one, as the quantity of air absorbed by the internal combustion motor cannot be easily modified, then, in or( er to 'reestablish the balance and to maintain the pressure statiol1ary,:'tlie best way is to modify, automatically or by hand, follovt 1e quantity of airjadmitted into the compressed air motor dl'- which supplies partly the energy for the propulsion.

The 'temperature in a submarine boat of `the typeI` described during the navigation under water tends to increase because of the heat Vradiating from the internal combustionmotor`and at the same time it tends to dimmish because the exhaust air of the compressed air engines although having-been- "previously heated 'is cold; there is therefore a certain compensation.

and expelled, together outside the Within certain limits and by the application of the means "generally known it is possible to diminishthe radiating heat of the motor and also the temperature of the exhaust air of the coinpressed air engines; but the best protection against the elevation of the temperature is afforded by the ventilation, which is very energetic in the boats of the type described because the Whole air, which is directly or indirectly used as mot-ive power is utilized c in it.

A serious inconvenience in the submarine boats driven under Water by an interna-l combustion motor is the bad smell produced vby the emanations of the fuel (mineral oil,

benzin etc.) reaching in the interior of the boat through .insufficiently tight joints of the pipes or due to leakages in various parts of the engine; to prevent the spreading of said emanations into the part of the boat occupied by the crew the following arrangement is adopted. The exhaust, air of all thecompressed air engines -lis discharged inside the boat at the end -.12- thereof usuallyioccupied by the crew, while the aspiration of the internal combustion motor. -1-2-3- takes place at the op posite end -14-' of the boat, so that the Wholeinside of the boat is constantly swept by a draft ofair. In anylpoint Whatever of the boat the speed of said air `current is in inverse ratio of the free crosssection afforded to its passage; therefore by means of suitable partitions -24- it will be possible to increase considerably the speed of the air current Where it will be necessary and arrange said partitions for instance in such 1nanner,-that in proximity.

of the engines'the current be strong enough to carry 0H to the other end of the boat any emanation Where the foul air is absorbed by the aspiration of the internal combustion mot-or.

To keep the boat at a constant v,depth during the navigation under water, the Weight of the boat must remain unaltered; therefore in the-boat the Weight of the exhaust gases of the internal combustion. motor discharged Aoutside must beI substituted by an equivalent Weight of water; and as the weight of the exhaust gases (at least for certain types of internal combustion ruotors) is almost in proportion of the number of turns of the motor, because the quantity of air absorbed at each pistons stroke is almost unvaried; and the Weight of the Afuel burned can be neglected in comparison with the-Weight of air necessary for the` venient capacity and actua-te by the motor for instance conveniently .connecting same llO with the propeller shaft, which pump introduces water from' the exterior through the pipe 26 when the motor is running. The weight of the exhaust gases at each turn of the shaft being a known quantity by a given motor, it'fol-lows that it will be an easy task to determine the size and the speed of the water pump which will keep the load of the boat unvaried.

In submarine boatsfor military services, it.- is desirable that the discharge of the exhaust gases of the internal combustion motor be suppressed when the boat gets very near the enemy because the bubbling caused -at the surface of the water by the said exhaust gases may help in detecting the presence of the boat. To avoid such inconven iece, the propulsion' in said case'is made as follows'. When the boat is very near the enemy, her engines are run exclusively as compressed air motors, the exhaust air of which is discharged, as before, into the inside of the boat. Under these conditions the barometrical pressure in the boat will increase slowly up until the maximum which the men of the crew and the resistance of the hull are able to support. It is easy to figure out, that before such limitis reached, a. sufiicient length of time will elapse to allow the boat to get away to a distance, where the bubbling can be no more noticed. Then the 'engine is again run, exclusively as an internal combustion motor in the same manner as when the boat is at the surface of the Water until the barometrical pressure in the inside of the boat lowers -anew to the normal atmospheric pressure; at this point the normal propulsion by the compressed air motor and the explosion engine will be resumed. It should be remarked' however that, as theinternal combustion motor could not work, properly where the external air pressure is sensibly superior to the atmospheric pressure, on the air inlet ipe must be provided an au tomatic reducing valve, -18- which brings the air pressure down to-the valueconvenient for the normal Working of the motor. In passing it should be remarked that by such a process the air is utilized twice as in the former case, but the 'two steps of the cycle are successive instead ofbeing simul-.

taneous. Therefore by adopting the system above described, the discharge of the exhaust gases outside of the boat can be su pressed during a limited-tim'e,and of this possibility the boat will take advantagev whenever the bubbling of the water at the surface becomes dangerous.

In sulnnarne boats for military service,

'the reduction to a minimum `of the time required by thelu'rat to pass from surface navigation to the submerged position is a very important feature. VThe immersion is obtained by fillingq with water-ballast tanks,

-erate as an air motor to ,assist it is important therefore, to perform this operation as quickly as possible and this can be done by producinga vacuum in the ballast tanks, 'for this purpose an air pump may be used, but the best means is to so arrange some of the cylinders of the internal combustion motor as to enable them to act as air pumps, for instance the same cylinder '-1 which according to the various circumstances acts as an internal combustion motor, as a compressor, as a compressed air motor, and as an air pump.

Claims:

1. In a submarine boat, an engine having a plurality of cylinders, an air compressor driven by said engine and a storage reservoir wherein the compressed air is stored: one of the cylinders of the engine adapted to act as an air' compressor, to effect a first step in the compression of the air while the i boat navicates at the surface air connections from said compressor cylinder to the first-A mentioned compressor to complete the air compression, connections from said reservoir to said compressor, -said air compressor operated by the remaining cylinders ofthe engine Working in the usual way.

2. In a submarine boat, the combination of a polycylindric explosion motor for propelling the boat, an air compressor for serving at will as an air motor to assist in propelling, a reservoir for compressed air, con- .nections between said compressor and reservoir, and connections between the latter and a. plurality of cylinders of the motor, whereby the latter is adapted at Will to oppulsion.`

3. In asubmarlne boat, the combination of a polycylindric lexplosion motor for pro'-l pelling the boat, an air compressor driven by said motor, a compressed air reservoir connected with said compressor, means whereby several cylinders-of the explosion motor a-re enabled to act as a compressed air motor atwll. to assist in the propulsion, and a reducing valve inserted between the aforesaid air reservoir and cylinders.

4. In a submarine boat, an engine for propelling the boat, an air compressor which,

at will, acts also as a compressed air reser-4 voir, means for admitting compressed air from the reservoir into the air compressor while acting as a compressed air motor, eX- haust connections from said compressed air 4motor to the interior of theboat, and feed connections from the interior of the boat to the engine, to supply air to the latter.

5. In a submarine boat, the combination of a polycylindric motor for propelling the vin the proboat, an air compressor driven thereby, a f

compressed air reservoir connected therewith, means wherebythe a1r compressor and 'a plurality of cylinders of the 'explosive motor are enabled to act, at will, as a compressed sion of the boat,connections as a compressed pressed air motor-io cylindersl oi the engine acting also as com' air motors, means for discharging the exhaust air of the latter' in the interior of the boat, and means Jfeeding into the remaining*cylinders o't' the explosion motor, air taken from the interior of the boat.

(3. In a submarine boat,the combination oli a combustion engine for propelling the same, a compressed air motor to assist in propelling the boat and having an exhaust valve, a compressed air reservoir and connections for feeding compressed air to cylinders of said motor, a closed vessel for receiving and circulating compressed air coming from the reservoir before reaching the cylinders, aforesaidY of the compressed air motor, and connections' between the exhaust valve of the engine and said closed vessel for allowing the exhaust gases of the engine to heat the air which is circulated in the closed vessel;

7. In a submarine boat, the combination of a polycyli'ndric engine for propelling `the boat, an air compressor, driven by saidV engine, a compressed air reservoir connected therewith and wherein the compressed air is stored, a plurality of thecylinders of the thermic engine adapted to' act, at will, as air compressors to effect a irst step in the compression of the air, connection from the air reservoir to the air compressor whereby the latter is enabled to act, at will, as compressed air motor to assist 4in propulsionfof the boat,l suitable connections between those cylinders of the engine' where the first step of the compression of the air is effected and the air compressor where the compression o air is completed, and a closed vessel for receiving the exhaust gases of the engine in order to heatthe compressed aircoming from the reservoir before reaching the air compressor when act-ing fas a compressed air motor;

8. In a submarine boat, the combination of a polycylindric engine for propelling the l l l l boat, an l air.

storage reservoir for compressed air, a numcompressor driven thereby, a*

adaptedlto act, at will, as air compressors ,e

to effect-a first stepof the compression, and a compressedair motor to assist inthe propulsion ofthe boat, a reducing valve inserted between' the air rservoir andthe mentioned cylinders of the engine, and a heating apparatus for receiving the exhaust gases of the cylinders acting as explosion engine, and a conduit connecting the storage reservoir,with the cylinders acting as com pressed-air-motors and passing through the heating apparatus, .whereby gases are utilizedfor heating the air which circulates in said conduit.

the exhaust y 9. In a submarine boat, a motor fr driving said boat, means foi-.causing said motor to also drive a compressor, when the boat is nea'r the 'surface of the water, a suitable reservoirfor storingsaid compressed air, a compressed air motor to assist in propelling the boat under water, connection from the res ervoir to .said compressed air motor for supplying compressed air to the lat-ter, an exhaust valveprovided on said compressed air motor and through which the interior of the boat, and inletvalves on the engine and which, when the boat is under water admit the air from the interior of theboat for gupporting combustion in the cylinders of the engine.

10. In a submarine boat, motor and a combustion engine having a plurality of cylinders, a vconduit for discharging the exhaust air of the cylinders which act as compressed air motors` at one end of the boat, another' conduit from the inlet valve of the engine to the other end of the boat, for supplying air to the engine, and partitions provided iu convcnimu; places inthe interior of the boat and reducing, at said places, the clear section, to increase the speed of the air current which goes from one end of the boat to the other.

In testimony whereof,-l. have signed my name' `to this specification in the presence of two subscribing witnesses.

J. GRoN, ILA. JOHNSON.

a compressed air air is discharged into

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