US2113936A - Steam engine - Google Patents

Description

A ril '12, 1938. E; L. FIKETT ET AL 2 113, 3 4 [STEAM ENGINE Filed July 21, 1934 4 Sheets-Sheet l fmz iz ATTORNEYJ April 12, 1938. E. L. FICKETT ET AL 2,113,935

. STEAM ENGINE Filed July 21, 1954 4 Sheets-Sheet 4 ATTORNEYS Patented Apr. 12, 1938 rarest caries STEAM ENGINE Ernest L. Fickett,

William 0. Forman, and Philip E. Arthur, Fitchburg, MassL, assignors toFitchburg Engineering Corporation,

Fitchburg,

Mass, a corporation of Massachusetts Application July 21, 1934, Serial No. 736,388

3 Claims.

The principal objects of this invention are to provide a simple and compact steam engine that willoperate at high speed; to provide hydraulic means for operating thevalves; to provide a hydraulic push rod without clearance and of the proper length at all times; to provide'a lubricatng system which will keep the so-called push rod filled with 'oil at all times; to provide a construction in which the cylinder is provided with anangular exhaust port and the piston head is of a generalconical shape having the same angle as the exhaust port for insuring a thorough sweeping of the piston head at each exhaust; to provide the cylinder block insuch a form that a steam jacket and inlet manifold are formed therein when the cylinder sleeves are pressed in; to provide it Witha shelf at the lower end forming a common exhaust belt of a plurality of cylinders, and to provide an improved governor for controlling the hydraulically operated valves.

Other objects and advantages of theinvention will appear hereinafter.

Reference is to be'had to the accompanying drawings, in which Fig. 1 is a side elevation of a three cylinder uniflow steam engine constructed in accordance with this invention, showingone end of it as a central sectional vertical view through the axis of the crank shaft;

' Fig. 2 is a sectional view of one of the cylinders on the line 2-2 of Fig. 1;

Fig. 3 is an enlarged sectional View of the. upper endof one of the cylinder heads;

Fig. 4 is an elevation of the same features;

Fig. 5 is a section of thecylinder head on the line 5-5 of Fig. 3; V a

Fig.6 is a central longitudinal sectional view of the governor and associated parts, and

Fig. 7 is an end view of the same with parts in section on the line '|-'l of Fig. 6.

The engine is shown as being mountedon and contained in a hollow casting H) which constitutes the base, frame, and easing of the machine. This constitutes a tank for oil and is provided with a compartment H extending lower than the rest of it and havinga drain l2 into it for the water collected at the bottom of the oil tank. At the oppositeend it is provided With another depressed receptacle l3 and the wall which connects it with the tank proper is provided with an overflow opening l8 which keeps the oil in the tank at such a level that the cranks will just avoid thelevel of the oil in' operation. The oil runs from the surface'of the oil pool in the tank into the secwith the exhaust port.

tion It which is the suction tank for the oil 7 pump, as will appear.

The entire framework is enclosed and all the mechanism is enclosed in it. Above the base Ill is located an upper casting it which is bored. out at IE to provide for the several engine cylinders H. In bearings, located between the two sections Ill and i5, is the crank shaft [4 having a fly wheel It or the like.

It will be seen that a straight hole can be bored vertically in the form shown, into this casing i5 and that the casting is so formed that, when these holes are bored and the cylinder sleeves ll pressed in, the steam jacket and the inlet manifold are formed. There is a second shelf ill at the lower end which bounds a common exhaust belt 22 for the several cylinders, communicating with the exhaust ports 23 which are drilled through the cylinders proper. These ports are drilled at a distance down on the stroke so that they are uncovered at practically nine tenths of the stroke downward and remain uncovered for the rest of the stroke. These ports are made at an angle and the angle ismade definitely'to match the angle of the dome shaped piston head 24. The ports are of sumcient length so that at the extreme end of the stroke the exhaust port extends a little below the piston head. This projection is made to insure'a thorough I sweeping of the piston head at each exhaust and provide adequate drainageiso that no water can be trapped and carried back up with the piston.

As has been stated, individual cylinder heads 25 are provided; having a conical shape so that the piston can go very close to the head, on its upward stroke, thus reducing the volumetric clearance. On the casting l5 lugs 26 are provided into which studs are screwed to secure the cylinder heads thereto. These lugs are not made continuous butare spaced apart inside so that a steam passage is left between each two successive lugs to allow, the steam to flow-upward and fill the space in the cylinder head above the top of the cylinder.

The cylinder is open centrally at the top providing a steam inlet port 21. A single beat poppet valve 28 is seated in the exact centerof each cylinder and, instead of being actuated by rocker arms or other mechanical devices, it is operated by a piston 29 rigidly fastened to the end of the valve stem 30. This piston is free to move up and down in a cylinder 3|, which constitutes the upper end of the engine. The piston rod, or

valve stem, is prov1ded with a fibrous packing '40 to prevent oil leaking down the valve stem from the operating piston. Steam is prevented from leaking up the valve stem from the steam chest by a series of grooves 4| in the nature of a labyrinth packing. An annular chamber 42 is formed in the valve stem guide below the fibrous packing. This is connected by a pipe 43 to the exhaust system of the engine to allow any water that works up the valve stem to be removed constantly from this point. Above the piston 29 a drain 44 is provided to take any oil that leaks by the piston back through this pipe to the crank case.

The cylinder below the piston 29 and the pipe connected to it are kept constantly filled with oil through a pipe 45 having a conventional check valve 45, see Fig. 4. This oil in the system is maintained by being connected to the pressure lubricating system of the engine. This pressure is available at all times when the engine is running by means of a pump 41 shown as a gear pump mounted on the frontbearing cap and driven by means of gears 48 and 49. As will appear, the gear 48 is connected with the crank shaft. This pump draws oil from the depressed portion l3 and at the front of the crank case through a pipe 56.

The main bearings are lubricated by pipes 5| receiving oil at a predetermined pressure from the pump 47. The magnitude of this pressure is determined by a spring loaded relief valve 52 connected into the system. A drilled hole 53 from the center of the main journal to the center of the crank pin conveys oil under pressure to the bearing,

The pistons 24 are of the trunk type and serve the dual capacity of piston'and cross head. The piston pin or wrist pin 55 is hollow and, to prevent steam passing into the wrist pin, the ends are counterbored, and after the pin is in place a Welch plug seals both ends. Each cylinder is provided at the bottom with an annular ring 56 which is provided with a low bottom or sump to collect any condensate that flows from the cylinder walls and a pipe 57 is used to drain it off to any desired point, as for example, the separating chamber H.

For the purpose of controlling the stroke of the plunger so that it will be proportionate to the load of the engine and for other well known purposes, a governor is provided. The gear 48 is pinned to the end of the crank shaft I4 and a splined shaft 58 to which the gear 48 is fixed is thereby fixed to the crank shaft. In this way the gear 48 serves the double purpose of driving the pump 4'! and furnishing a non-slip drive for the shaft 58 which is the governor shaft. The two pins are driven into the crank shaft after the engine is properly set. No angular movement of these shafts can occur thereafter.

A'governor frame 60 is provided which constitutes a hollow casing for receiving the entire governor. This governor is provided with a series of radial cylinders 6! in which are located plungers 62, each one preferably having a spring 63 behind it. Pivotally mounted on a stationary part' are bell cranks 64 having the governor weights located upon them. Their inner ends are located in the yoke 65 movable in an axial direction, the movement being resisted by a spring 55 which is held in a cap 61 adjustable. in the frame to adjust the governor. Movable with this sliding frame 65 is a cam F58. Rollers 69, one to each engine cylinder and one to each plunger 62, bear on this cam. The cam is of the variable lift type. The lift commencesat a constant anr gular position on the cam and the recession is a constant variable along a spiral path. Thus, while the valves are always open at the same position on the stroke, the cut-01f is governed by the time of their closure. The cam is shown in Figs. 6 and 7 in a position to give maximum valve opening and it is held in this position by means of the spring 66, the compression of which is determined by the adjustable cap 61.

As the engine speeds up, the governor weights on the bell cranks 64 are thrown outwardly by centrifugal force. This causes a reaction on the frame 65 and against a hardened wear member 10 inserted in the end of the shaft 58 at the point of impingement. It is obvious that an outward movement of the governor weights will cause the governor carrier and cam to slide along the shaft in a direction to compress the spring 66. This, of course, moves the cam under one of the several rollers 69 to a point of lower rise and shorter opening on the cam.

In case of what would be called a runaway speed, the weights move out a sufficient distance so that the concentric portion of the cam will be under the roller and no plunger movement would result. Of course, a number of valve operating cylinders BI is provided to correspond with the cylinders and they are equally spaced circumferentially. Thus a single lobed cam will operate properly a chosen number of cylinders. The spring behind the valve operating cylinders is used for extremely high speeds and it is employed to insure the plunger 62 followingthe cam.

,Each of the plungers 62 acts to apply pressure through a pipe H to the plunger 29 and operate the valve 28. It will be understood that the pump 47 keeps an otherwise constant pressure on this plunger and that this additional pressure of the individual plungers 6? causes the operation of the valve. 11; will be observed that the oil in each one of the pipes H is under pressure at all times and this oil serves as a liquid push rod which, of course, will'be at proper length at all times and it operates entirely without clearance.

In following the operation of a single cylinder, let it be assumed that this cylinder is 'full of oil as is also the pipe H and the portion of the cylinder below the piston. Let it be also assumed that the roll 59 for that cylinder is raised on a base circle of the cam. There is an initial or static pressure in this oiling system equal to the pressure of the lubricating system. The cam 68 now revolves until it lifts the plunger in question. The oil is prevented from flowing back to the lubricating system under the influence of a higher pressure by the check valve 46. Consequently, any further movement of the plunger 62 must lift the piston 29 and admit steam to that cylinder. The action of the steam coming in through the inlet 20 and filling the space above the conical dome of the cylinder pushes down the working piston in the cylinder and the regular functions of the steam engine are carried on thereafter, as will be obvious. When the plunger 62 again reaches the concentric portion of the cam, if there has been any leakage in the oil system, this will be immediately replenished through the'check valve 46 because the pressure outside the system is higher than that inside.

The engine is constructed so that the piston 29 is packed by means of a fibrous packing 48 so that very little leakage occurs at this point. The plunger 62, however, has merely a sliding fit in the ring and there is some leakage at this point.

comparatively simple and when manufactured it This is premeditated and provided for because this leakage at the bottom, or cool end, of the valve lifting system serves to oil the plunger and its roller and pin. It also allows a little fresh oil to be taken in at the upper end of the system on each stroke. In this way, eventually all the oil in the valve operating system will be changed. Thus the retention of oil in the upper end of the system which is comparatively hot, is prevented.

The engine is arranged so that the overflow from the engine lubricating system and from the spring pressure release valve is discharged into the governor case, thus effectively lubricating the governor and all its associated apparatus.

This engine is designed for high speed operation and it is found effective to secure speeds not usually operative in reciprocating steam engines.

, municating with the exhaust ports of all the cylinders also is a feature of importance. The intake provides a body of live steam around the tops of the several cylinders at all times and the exhaust steam also constitutes a jacket around them at a lower level.

By means of the combination the angularly,

disposed portsin the cylinders and the conical top surface of the piston, not only is the flow of steam outwardly interrupted but by arranging tem prevents the carbonization of the oil by the heat. The whole design is of such a nature as to protect the operating parts from becoming cooled by outside air and acquiring a deposit of dirt or dust and also provides a compact construction. The manufacture of the engine is is particularly suitable for high speeds.

Although we have illustrated and described only one form of the invention we are aware of the fact that modifications can be made therein by any person skilled in the art without departing from the scope of the invention as expressed in the claims. Therefore, we do not wish to be limited in this respect otherwise than as set forth in the claims, but What we do claim is:

1. In a steam engine, the combination of a main engine cylinder, crank shaft, and piston,

the cylinder having a port for the admission of steam, a valve for controlling said port, a cylinder and piston connected with the valve, a crank shaft operated directly by the engine piston, a pump connected with the engine crank shaft to be operated thereby, a check valve con- 'nected with the pump for keeping a predetermined pressure of oil on the last named cylinder, and means operated by the. crank shaft for periodically increasing the pressure under the secondlpiston to open the valve, said means comprising a column of liquid which acts as a push rod operating without clearance.

2. In a steam engine, the combination of a main steam cylinder having a steam admission, valve, a piston on the stem thereof, a second cylinder in which the piston is located, a main piston in the first named cylinder, a crank shaft pivoted to and operated by the main piston, a pump operated by the crank shaft and arranged to supply oil to the second cylinder to normally keep the pressure on the first. named piston but not enough to open the valve, means including a pressure relief valve for regulating the pressure and keeping it constant, and a column of liquid connected with the cylinder and operated by the crank shaft for increasing the pressure in the first named cylinder periodically and opening the steam admission valve.

3. In a steam engine, the combination of a crank shaft, a plurality of pistons connected therewith, a main engine piston and cylinder, an inlet valve for one of the first named pistons and cylinders operated by the second piston and cylinder, means including a pressure relief valve for maintaining a predetermined pressure on the second; piston when the engine is operating, a cam rotatable with the crank shaft, a series of plungers, one for each main cylinder connected to be operated by said cam, and a column of oil between each plunger and the piston connected for operating the correspondingvalve, whereby as the cam rotates it will operate the plungers in the proper sequence to apply pressure to the oil in said column and actuate the valves.

7 ERNEST L. FICKETT.

WILLIAM O. FORMAN. PHILIBE. ARTHUR.

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