US2397977A - Compounding system for steam locomotives - Google Patents

Description

April 9, 1946. R. M. OSTERMANN.

COMPOUNDI NG SYSTEM FQR STEAM LOCOMOTIVES Filed Jan. 11, 1945 INVENTOR. 3M5 J1 fls/ermmm Patented Apr. 9, 1946 COlWPOUNDING SYSTEM FOR STEAM LOCOMOTIVES Rudolf M. Ostermann, Evanston, 111., assignor to The Superheater Company, New York, N. Y.

Application January 11, 1945, Serial No. 572,402

Claims. (01. 6065) l is partially expanded before it gets to the cylin- The present invention relates to steam locomotives and particularly to improvements in the arrangements for utilizing steam in the engines thereof.

When single expansion steam locomotives are equipped with boilers capable of being forced to produce more steam than the cylinders can efliciently use at relatively high boiler pressure, of say 250# pressure or more, the locomotive engines are normally operated with unusually long steam admission periods, thus obtaining an unusually large amount of power for train haulage. With the steam admission periods so lengthened, the expansion periods are of necessity decreased, and therewith the volume ratio of the steams expansion. Such operation results in producing the desired amount of excess power but in a very inefficient manner because the steam cannot be expanded to near atmospheric pressure as it should be for best efiiciency. To change the design of a single expansion locomotive of a given boiler pressure so that it might produce more horse power with efficient expansion would require increasing the size of the cylinders and therewith also the tractive force. However, in order to operate a' locomotive without undue slipping of the wheels, the cylinder and piston diameters, which determine the tractive force, must be strictly limited to the ones with which the steam of boiler pressure does not produce a bigger piston thrust and a bigger tractive force than can be safely employed with the frictional adhesion of the locomotive wheels. For this reason, it is impractical to equip over-boilered reciproeating single expansion steam locomotives with cylinders large enough fOr an economical expansion of the steam. However, it is possible to modify the expansion ratio of a reciprocating single expansion locomotive and increase the efficiency of its steam use under varying load conditions by utilizing a primary expansion steam turbine so combined with the cylinders of a locomotive engine that the latters full starting tractive eiiort is produced by the action of steam of boiler pressure against the pistons, while, as the locomotive speed increases, the steam pressure upon the pistons and the torque produced by the pistons upon the drivers are automatically decreased at any cutofi. At the same time the decreasing cylinder tractive effort is supplemented with a tractive efiort developed by the turbine orturbines also coupled to the driving Wheels of the locomotive. The steam on its way to the cylinders flows through a turbine or turbines and ders of the locomotive for final expansion.

Such a compounding arrangement is to be distinguished from the arrangement in Ostermann and. Williams United States Patent No. 2,102,806

which also combines a, primary expansion turbine with a secondary expansion reciprocating engine jointly driving the axles of a locomotive but in which the tractive effort is manually regulated by altering only the cylinder cutoff, i. e. by manually altering, with it only, the mean effective piston pressure, with any given engine admission pressure. In that system automatic regulation, by throttling, of the pressure at which the operating steam is admitted to the primary expansion turbine so as to produce an engine admission pressure which does not unduly vary at any 10- comotive speed, is resorted to in order to leave the operator free to adjust the working cutoff of an oversized cylinder, to the varying needs of the train propulsion without ever producing enough buildup of pressure against the pistons to slip the driving wheels. Clearly, slipping the drivers would be inevitable without some sort of automatic throttling of the primary steam pressure, and Without thus limiting the cylinder admission pressure automatically. v

While the arrangement described in this earlier patent, 2,102,806, is workable, it has the disadvantage that the throttling of the steam, before it enters the turbine, destroys part of the potential opportunity for primary adiabatic expansion in the latter. It therefore lowers the efiiciency with which the internal energy of the steam that propels so compounded a locomotive, is transformed into mechanical energy. After further consideration and study of this general type of locomotive compounding arrangement, I have come to the conclusion that this disadvantage of the system as in Patent 2,102,806 can be avoided, and that a compound locomotive with a primary expansion turbine and a secondary expansion reciprocating engine is, without the need of any steam throttling, practical enough, provided the turbine is so designed that the total cross sectional area of its steam flow and of the steam impingement upon its vanes is made variable at will, as well as the cylinder cutoff, and that the turbine or turbines be compounded with cylinders which have pistons no larger than those which produce the requisite maximum tractive effort with full boiler pressure upon them.

In the drawing:

Figures 1 and 2 illustrate an application of my 66 compounding system to a single expansion twocylinder steam locomotive in elevation and section respectively.

Figure 3 shows the partial development of a steam turbine with one of its controlling nozzles.

Figure 4 is a partial plan view of the turbine steam chest indicating how a multiplicity of controlling nozzles may be applied to the turbine, so as to vary the area of steam impingement; and

Figure 5 is an enlarged view of a cab indicator provided for maintaining the proper relation between steam consumption of the turbine and the cut-off or expansion'ratio of the reciprocating engine.

Referring to Figure 1, steam from the boiler I, which is operated as usual to maintain a constant steam pressure, enters dry pipe 2 to pass to super-- alternate sides of it, and the reciprocating motion of the valves I2 interconnected with the pistons through valve gear l5 causes the steam to be i 7 finally exhausted from the cylinders through ports Ma and I4?) in the usual manner of a reciprocating steam engine.

While the pistons 13 revolve the main driving axle 46 of the locomotive in forward motion by means of main pins l1 and main rods l8 in the usual manner of a locomotive drive, the turbine 1 drives the same axle through shaft 20. reduction gear 2|, shaft '22 and worm gear 23 and 24, in the same sense of rotation as the crankpins l l. The travel of the valves I2 is, as usual, lengthened or shortened by a cab lever 25 which con meets to valve gear means l5 through levers and rods 26, 21 and 28, thus altering the valve cutoff in forward motion of the locomotive.

The turbine steamchest 5 contains a-multiplicity of valves 5a opened and closed at will by cams on a camshaft 5b which is rotatable by means of gears 29 and 39 interposed in shafts 3| and 32, th'elatter carrying a handwheel 33, also within the cab of the locomotive. By turning the handwheel 33 individual valves 5a can be successively opened and closed, thereby increasing or decreasing the total turbine wheel area which is impinged upon by the steam on its way to the valves of the engine in forward motion. When the cutoff lever 25 is in a position to the left of vertical in Fig. 1, the link blocks l5 are in the upper half of links I51), and the movements of the valves l2 in relation to those of pistons l3 are altered in phase producing a reverse motion of the engine. During reverse motion all of the valves 5a are closed and steam is supplied to the engine directly fromsteam pipe 4 by means of reversing throttle 34 controlled by cab lever 35 through'rods and" levers '36, 31 and 38,'thus by-passing the turbine 1. Theabove described system for compounding a turbine utilizing unthrottled steam at constant pressure with a reciprocating engine or other secondary steam engine is described and claimed in my co-pending application Serial No. 615,995,

I which was filed September 1 1945. a a ntinuation-in-part hereof.

A gauge 39 is located in the sight of the engineer, to indicate the pressure within the'pipe 9 to which 'it isi'connected by pipe 40. Fulcrumed' The valve cavities of chest 5 are conon the axis of the gauge pointer is a double arm lever carrying a target 4! whose position is al tered in conformance with changes in the position of cut-ofi' lever 25, the two being mechanically interconnected as by an adjustable push and pull cable control.

The gauge 39 has a scale 44 graduated to show steam pressures and alined therewith are graduations 45 representing the optimum cut-01f at which the reciprocating steam engine should be operated for the various pressures existing in the turbine exhaust pipe 9. Or stated differently,

the graduations of scale 44 represent the steam pressure that should be maintained in pipe 9 by regulation of turbine valves 5a for the preferred cut-ofi for engine I I under various operating conditions. The target 4| and gauge 39 could be separately mounted but one of them would then preferably be provided with both scales 44,45 or at least with the scale pertaining to the other indicator so that, for example, reference to target 4! would indicate the proper pressure to maintain for a particular cut-off; or, vice versa, the

gauge pointer 5| would indicate the proper cut-' off for the pressure maintained.

In Fig. 3 there is shown a sectional development of the turbine 1 with one of its nozzles 6,

two rows of revolving vanes 41 and 48 and one The construction row of stationary vanes 49. as indicated represents a well known standard of impulse turbine design, the nozzles being divergent below their throats, representative of nozzles which expand the steam to a supersonic velocity before it enters the turbine wheels. However, the turbine is so shown only by way of example, since our invention is not limited to impulse turbines, but may be also practiced with reaction turbines, in which the steam enters the turbine rotor at a relatively lower velocity and in which the steam pressure is gradually lowered as the steam passes between the vanes of successive turbine wheels,

In-Fig. 4 a" partial plan view of the turbine steam-chest is shown; and two of the flanges 53 of a l-nozzle turbine to which connect the pipes 9a, 8b, 8c and 8d which carry thesteam to the four nozzles 6 from the multiple valve chest 5. My invention is not limited to the use of any particular number of nozzles, and Fig. 4 should.

be regarded as being merely illustrative of a general arrangement.

The compounding arrangement described above functions as follows: Thelocomotive is started with the cab lever25 in the forward corner in which position the cutofi of the valve I2 is the longest possible withthe particular valve gear design. Enough of the turbine valves 5a are opened by turning handwheel 33 to start the train without slipping of the driving wheels. Since the turbine l is at rest in starting, the full boiler pressure will build up'in pipe 9 and against the pistons 13 causing the pointer 5| of the gauge 39 to indicate this full boiler pressure. In Fig. 5 the gauge is assumed to be so constructed that full boiler pressure in pipe 9 swings the pointer 5| to the extreme left on the scale. The target 4| when moved to the extreme right indicates maximum cutoff of the enginevalves I2. As the locomotive speed increases, and the turbine accelerates, and increasingly larger steam volumes are displaced by'the engine pistons-l3 in a unit of time, the pressure in :pipe 9 drops. This is because the steam volume demand eventually exceeds thefixed steam discharge capacityof the turbine nozzles 6 to which steam flows from the opened valves a. What steam does. pass through the opened nozzles, expands in them below their throat, steam pressure is converted into steam velocity, which latter is morev and more completely abstracted by the turbine vanes, thereby producing a turbine torque which assists the reciprocating engines in turning the drivers, and which torque increases as the engine torque decreases because of the drop of pressure in pipe 3 and against the engine pistons l3. The locomos tive may conceivably be accelerated with lever 25 in the extreme forward position and with all the valves 5a open, until the pointer 51 gradually swinging to the right as it indicates decreasing pressure, stands opposite the target 4|. The mechanism 42 which coordinates the movement of the lever 25 and the target 4| is adjusted so that the target points in any position of the lever 25 to a pressure .on the gauge which is the minimum required in pipe 9-lest the expansion in the steam in the cylinders be carried below a practical release pressure at the point at which the valves [2 open to the cylinder exhaust. On most locomotives the boiler capacity is not sunlcient to operate with maximum cutoff at highest running speed and the piston displacement during steam admission has to be reduced by shortening the valve cutoff with lever 25 long before the maximum running speed is attained.

This in tum moves the target 48 to the left from its extreme right position. The engineer should then manipulate the handwheel 33 and adjust therewith the position or camshaft 5b and valves 5a so that the gauge pointer always coincides with the position of the target, or else remains slightly to the left of it, thus making sure that at all speeds and loads the boiler steam expands with as large an expansion ratio as possible down to a release pressure which is still adequate for providing the proper boiler draft. In that manner the present compounding system produces the largest possible steam economy at all locomotive forward speeds and loads. Inasmuch as steam locomotives in road service are operated in reverse only at very low speeds and through short distances, as in switching and making up trains, or when run without train, a separate reverse turbine may be readily omitted. When wishing to reverse the engine valves 12 are properly adjusted, all the turbine valves 5a are kept tightly closed and steam is admitted through opening the reversing throttle 34 with cab lever 35. If reverse rotation of the turbine wheels in a steam atmosphere, which would create some heat by friction and windage is objectionable, a valve means 52 (shown in dotted lines in Fig. 1) may be provided and be mechanically interlocked with the reversing throttle mechanism so as to close this valve when the reversing throttle is open and vice versa.

I do not wish to limit my invention to the use of one turbine exhausting a pair of cylinders of a reciprocating steam locomotive. Quite evidently the invention as hereinafter claimed may be practiced with equal success when the pairing of one turbin with each cylinder of a locomotive is found to be structurally preferable, ,provided the cutoffs on all cylinders are jointly altered by one lever, and also provided that the steam admission to all turbines is simultaneously regulated by one manipulation, with equal steam flow through all of them.

What is claimed is:

1. In a locomotive having a superheater equipped boiler for supplyin superheated steam at :substantially'xconstant pressure to a primary expansion steam. turbine provided with multiple valve means for varying the areas of passage ofunthrottled superheated steam through the turbin vanes, a secondary expansion reciprocating engine having adjustable cut-off valve means ror'varying the steam expansion ratio in said engine, and a conduit connected for supplying all of the steam from the exhaust of said turbine to said engine{ means for indicating the operative position of said cut-off valve including a movable target; means for measuring the efiective steam pressure in said conduit; and a movable indicator responsive to said measuring means and disposed to travel in a path parallel to that of said target,'whereby said valve means may be adjusted to align said indicators and thereby attain optimum steam use for each position of said cut-off valve.

2. In a locomotive having a superheater equipped boiler for supplying superheated steam at substantially constant pressure to a primary expansion steam turbine provided with multiple valve means for varying the areas of passage of unthrottled superheated steam through the turbine vanes, a secondary expansion reciprocating engine having adjustable cut-off valve means for varying the steam expansion ratio in said engine, and a conduit connected for supplying all of the steam from the exhaust of said turbine to said engine; means for indicating the operative position of said cut-01f valve including a movable target; means for measuring the eifective steam pressure in said conduit; a movable indicator responsive to said measuring means and disposed to travel in a path parallel to that of said target, and scales for the respective indicators positioned to align the graduations representing the optimum steam admission pressures to said engine with corresponding graduations representing the related position of said cut-off valve, whereby said valve means may be adjusted to align said indicators and thereby attain optimum steam use for each position of said cut-off valve.

3. In a locomotive having a superheater equipped boiler for supplying superheated steam at substantially constant pressure to a primary expansion steam turbine provided with multiple valve means for varying th areas of passage of unthrottled superheated steam through the turbine vanes, a secondary expansion reciprocating engine having adjustable cut-oil valve means for varying the steam expansion ratio in said engine, and a conduit connected for supplying all of the steam from the exhaust of said turbine to said engine; means for indicating the operative position of said cut-ofi valve including a movable target; means for measuring the effective steam pressure in said conduit; and a movable indicator responsive to said measurin means and a scale for at least'one of said indicators having graduations thereon that represent the positions of said cut-01f valve arranged in alinement with indicia that represent the optimum steam pressure in said conduit for each position of said cut-off valve.

4. In a locomotive having a superheater equipped boiler for supplying superheated steam atsubstantially constant pressure to a primary expansion steam turbine provided with multiple valve means for varying th areas of passage of unthrottled superheated steam through the turbine vanes, a secondary expansion reciprocating engine having adjustable cut-off valve means for varying the steam expansion ratio in said engine,

and a conduit connected for supplying all of the steam from the exhaust of said turbine to said engineymeans for indicating the operative position of said cut-off valve-including a movable target; means for measuring the efiective steam pressure in said conduit; and a movabl indicator responsive to said measuring means and a scale' for at least one of said indicators having graduations thereon that represent an optimum steam pressure to be maintained in said conduit for each position of said cut-ofi valve,

5. In, a locomotive having a superheater equipped boiler for supplying superheated steam at substantialy' constant pressure to a primary expansion steam turbine provided with mutiple valve means for varying the areas of passage of indicating members; means for operating one of.

said members in response to movement of said cut-ofl valve to various positions; means for measuring the effective steam pressure in said conduit; and means controlled by said measuring means for operating the other of said indicating members.

RUDOLF M. OSTERMANN.

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