US2476857A - Expansion chamber - Google Patents

Description

July 19, 1949. N. GRAFINGER EXPANSION CHAMBER 3 Sheets-Sheefl Filed March 8, 1946 INVENTOR Lou/5 A4 Gm f/nyer WITNESSES:

(fl-7m ATTORNEY July 19, 1949. N. GRAFINGER EXPANSION CHAMBER 3 Sheets-Sheei 2 Filed March 8, 1946 INVENTCR Lou/'5 AZ Graf/hyez WITNESSES:

BY few/2. T

ATTORNEY July 19, 1949. GRAFI ER 2,476,857

EXPANS ION CHAMBER Filed March 8, 1946 3 Sheets-Sheet s WITNESSES! INVENTOR 25 7/1 W Law's A4 Gmfihyen EJMW flux 6. Mp4, 44

ATTORNEY Patented July 19, 1949 EXPANSION CHAMBER Louis N. Grafinger, Sharon, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application March 8, 1946, Serial No. 653,187

2 Claims.

This invention relates generally to starting devices, and more particularly to devices of this type which are suitable for accelerating a load unit to a relatively high speed in a relatively short period of time.

The Government of the United States has been granted a certain royalty-free license for governmental purposes with respect to the invention disclosed herein.

This invention is specifically adapted for starting free spinning gyroscopes of the type utilized in the directional control of torpedoes: However, it will be apparent to one skilled in the art that this invention has general application and may be utilized in the starting of a wide variety of load units, for example, the starting gear of internal combustion engines.

In certain of its aspects this invention is related to a copending application of L. B. Lynn, Serial No. 653,186, entitled Control devices, filed on the same date as this application, and assigned to the same assignee as this invention.

In certain other of its aspects this invention is related to a copending application of L. D. Jennings, Serial No. 653,190, entitled Cartridge starting mechanism, filed on the same date as this application and assigned to the same assignee as this invention.-

In the operation of torpedoes for directional control purposes, it has been found satisfactory to employ gyroscopes of the free spinning type, that is, gyroscopes which are brought up to a fairly high speed prior to the time of launching of the torpedo and then permitted to spin free for the duration of the torpedos run. Such a run is of stuliciently short duration both for test or exercise and war shot purposes that the gyroscope does not decelerate sufficiently or to a point where it no longer functions effectively as a directional control device.

The starting requirements for a gyroscope of the type generally described are rather severe. With modern electrically operated torpedoes the practice is to insert the torpedo in the torpedo or launching tube and then to apply the air pressure source to the tube to eject the torpedo therefrom. Usually about one-half of a second is required for the torpedo to move from the launching tube. In that interval the torpedo is accelerated to approximately full speed. During this interval such preliminary operations as bringing the directional control gyroscope up to speed, must be accomplished. Otherwise the torpedo will be inadequately controlled after launching.

Numerous devices for starting torpedo gyroscopes have been considered and experimented with. One form which proved successful and could be cheaply manufactured involved a small electric motor energized upon closure of the torpedos trigger switch the instant torpedo movement from the launching tube began. These motors were designed for short life, since their useful purpose was fulfilled in a matter of less than one-half of a second after operation began. In this brief interval the motor accelerated a two pound 3%; inch diameter gyro wheel to a speed of about 12,000 E. P. M. t

There are applications in torpedoes, for example those involving a primary battery as the main source of propulsion energy for the torpedo wherein it is not always convenient to provide suiiicient secondary battery energy to drive the gyroscope motor prior to launching. The use of compressed air and suitable mechanical cou pling offers a solution to the problem but has the attendant disadvantage of the space required for an air reservoir together with other equipment for controlling the air supply. Rather than this, the use of a cartridge as the energy source for starting the gyroscope appears to ofier the more sensible solution.

However, a very definite problem is involved in the use of a cartridge as the energy source due to the high rate at which gas pressure is built up. In early experimenting with cartridge starting devices in which the products of combustion of the cartridge were applied to a turbine connected to a gyroscope, it was found that the accelerating torques were so high that torsional shearing of the shaft connecting the turbine and load unit frequently occurred. In other cases when the shaft carried the load without failure, it was found that while the initial acceleration was extremely high the available energy was so inefficiently utilized that acceleration to full speed of the load unit was not obtained.

This condition was overcome in part by utilizing cartridges in which slower burning powders were employed and also by graduating the powder pellet sizes along the length of the cartridge to additionally control the combustion. Further improvements were realized by the addition of suitable screens between the cartridge and the exhaust port in the cartridge chamber to prevent the ejection of partially burned pellets from the cartridge chamber, as described in the mentioned copending application of L. D. Jennings, Serial No. 653,190. vThe screens thus confine combustion and, hence, gas pressure build up to the cartridge chamber which increases the overall eificiency. V r

While the foregoing expedients measurably improve the operating characteristics, the acceleration obtained is yet measurably higher 7 than is required for most applications. Better overall results can be obtained by reducing the peak pressureandgthezrate of build up of pres-j.

sure and to increase the duration of the pressure,

which through the turbine has the effect of supplying to the load unit a reduced torque of greater duration. Accordingly, a principal object of this invention is to provide an impulse-starter mechanism of the class described in which optimum accelerating characteristics for a particular load unit are obtainable.

Another object of this invention is to provide complete combustion of the powder takes place.

an impulse starter mechanism of the class described embodying a cartridge as the energy source in which-,the'products-of conibustion of the cartridge are controlled to providea satis factory pressure-time.characteristic.

A further object of this invention is to provide an impulse starter. of the type referred to in which the availableenergy producedbydetona tion of a'cartridgeisefliciently utilized.

Further separate-and combined objects of this invention are. to; provide an impulse. starter mechanism, utilizinga cartridge as the energy source, whichzis compact-.and'light in weight'in relation to power developed, which is simple in mechanical detail and@ cheaply; and easily manufactured, which requires a minimum' of maintenance effort and'which rapidly and uniformlyaccelerates a load, unit coupled thereto with a minimum of mechanic'al shock.

The foregoing statements are merely illustrative of the various aims and advantages of this invention. Other objects and advantages, will becomeapparent upon a study-of the following specification when considered in conjunction with the accompanying drawings, in which:

Figure 1: illustrates an. assembly, partly. in .sectionof an impulse starter mechanism embodying the principlessofthis invention,

Fig. 2 is a modification of the. invention-illustrated in Fig. 1, and; r

Fig. 3 is another View of the invention illuse trated; in Big. 2 showing, the turbine and'assoie ciated declutchingmechanism in longitudinal section.

Referring now to Fig. l of the drawings, nu-;. 'rneral I designatesthecartridgeiiring deviceand:

numeral '2; denotes the turbine mechanism.

The cartridge firing; deviceincludes a block? which maybe of bar stock having formed therea ina cartridge chamber 4-for-receiving a cartridge 5. The breech end of 'the block3 is so-designed that the cartrid emay; be inserted directly into the cartridge chamber. At the end of block 3 opposite the breech end thereof an opening 6 is provided of smaller diameter than-- the cartridge chamber, thus providing a-shoulder against which screen I may 'bear. The'length of the cartridge chamber is such asto accommodate the cartridge 5 and screen T as; illustrated. The.

breech endofblockS-issealed-by means of the breech block!) which threads over, the threaded section of block-3 and clamps-the cartridge rim therebetween. Several types of cartridges are available. The type here illustrated is equipped with twodetonating cannon caps connected in;

paralleLcircuit relationacrossleads l3 and I5;

h-P s mm. e ar r d e im n s ol in the breech block 9. The cannon caps are highly sensitive and are readily detonated by a small impulse of electrical energy, for example, that obtainable from a small permanent magnet impulse generator.

It has been found in using cartridges as the 7 in the cartridge chamber causing effective application-of gas pressure tothe turbine and addi 'tionally maintaining a high pressure and tem- Peretur in e cartr d ham e o o w h areessential to complete combustion. I

The'turbine is composed of apair of circular, endplates 25 and 26 (see also Fig; 3) between;

which are placed and secured at equal peripheral distances the nozzleblocks 21. Bearing supports 28 V and 29 arerespectively secured centrally. of" the end plates 25and 25, bearing support 28 be-',

ing provided with a concentric insert 3il having a peripheral groove. 3 I, the assembly forming an annular passage 32. Each of the nozzles 21 com- .municates with the annular passager32 through tubes 33 and the cartridge; chamber 4 is connected with theannularpassage by the threaded tubular section 34. One end of the turbine shaft 35 is housed in a bearing 36 secured in concentric .7 insert 30, while theshaft portion on the opposite ,7 sideofturbine rotor.31 is carried in'a bearing 38.

A. threaded extension 39.-of the turbine shaft, ex tending through the; bearing housing 29 is journaled in,a bearing- 40 inthe extreme end'of the housing zil A 'nut-4l is threaded over, the threaded shaft section 39 and is'keyed against rotational movementin the axial grooves 42- formed internallyof bearing-housing;29. Ture. bine shaft 35 is biased tothe right asyiewcd by the spring and plunger assembly 43. .Qne'elea, ment 44 of a clutch assembly- 45 is keyed to the;

extremity of shaft extension .39. Clutch ele'-' ment 46 .is connected to a shaft 41 which is connected. toaload unit (not shown), for'example,

the directional control gyroscope of a. torpedo. V

The blades or buckets 50 of the turbine 31 are milled about the periphery of a blank having the cross sectional configuration seen in Fig. 3;

The device thus far described is operable as hereinbefore. noted. HOW ver, measurable im.

provements. are achievable by the addition of the expansion chamber. 5'2 which. threads into the block 3 and communicates with the opening (5; between the cartridge. chamber and turbine through the. orifice 53. The purpose of the expansion chamber-is to convert, what would be a large torque of .very short .durationto a smaller torque of longer duration,

bieeds off through theorifice into the expansion chamber.

neously therewithnut 4| travels along threaded section 39. -B leeding. ofi of'the gas continues until the. gas pressure peak is I reached. and then.

. begins to fall. The pressure differential; reverses.

7 When the cartridge is. fired, the high pressuregas is appliedstofthev turbine. I Some of this-gas;

The gas impinging on the turbine blades drives the turbine in v rotation and-the load attached thereto is accelerated. simultar and the high pressure gas in the expansion chamber is supplied to the turbine tending to maintain the pressure. The total effect of the expansion chamber is thus to reduce the peak pressure and the rate of build up of the pressure and to increase the duration of the gas pressure. Since the turbine torque is a function of the gas pressure, the accelerating torques applied to the load unit are thus relatively uniform and mechanical shock as a consequence is minimized. When nut 4| reaches the limit of its axial travel, the turbine shaft which is yet rotating is moved axially to the left against the bias of spring and plunger assembly 43 disconnecting the turbines from the load unit at clutch 45.

In Figs. 2 and 3, the expansion chamber 52a is arranged as a shell about the cartridge chamber. It is reinforced by a metal band 55 arranged centrally thereof and is in communication with the cartridge chamber through a plurality of radially disposed holes 56. The function here is the same as that of the invention illustrated in Fig. 1; hence, a further discussion thereof is deemed unnecessary. The advantage of this embodiment resides primarily in the compactness of the structure provided.

The foregoing disclosure and the showings made in the drawing are merely illustrative of the principles of this invention and are not to be interpreted in a limiting sense. The only limitations are to be determined from the scope of the appended claims.

I claim as my invention:

1. Apparatus for controlling the gas pressure resulting from detonation of a cartridge in a cartridge chamber comprising, in combination, a block having a cartridge chamber formed therein and an orifice therethrough communicating with said cartridge chamber, screen means arranged in said block between said orifice and said cartridge chamber, said block having a plurality of holes therethrough communicating with said orifice, and a casing of larger cross sectional dimension than said block and having the extremities thereof flanged inwardly against said block and sealed thereto in position straddling said holes to form a chamber about said block.

2. In combination, a member of circular cross section having a cartridge chamber formed therein and an orifice extending through the end thereof in communication with said car tridge chamber, said block further having a plurality of radially disposed holes therethrough communicating with said orifice, a metal housing concentrically arranged in spaced relation about said member and straddling said radially disposed holes, and means sealing the extremities of said metal housing to said block so that said orifice communicates with the chamber formed by said housing about said member through said radially disposed holes.

LOUIS N. GRAFINGER.

REFERENCES CITED The following referenlces are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,884,479 Woolson Oct. 25, 1932v 1,935,123 Lansing Nov. 14, 1933 2,172,124 Gilbert Sept. 5, 1939 2,375,029 Nardone May 1, 1945

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