US1594082A - Steam engine - Google Patents

Description

July 27 1926.

E. C. WALKER STEAM `ENGINE .'5 Sheets-Sheet l Filed Feb. 25, 1920 fw/ W/er ze! am@ 7%@ July v27, 1926.. 1,594,082

- E. c. .WALKER STEAM ENGINE Filed Feb. 25, 1920 5 sheets-sheet 2 I invention,

'Patented .Iuly 27, v1.926.

.UNITED STATI-:s

1,594,082 NT OFFICE.

PATE

EARL C. WALKER, OF CANTON", ILLINOIS, SSIGN'OR T0 WILLIAM INGERSOLL, OF

I CANTON,' ILLINOIS.

s'rEAM ENGINE.

Application led February 25., 1920. Serial No. 361,186.

`This invention relates to improvements in steam engines and has for its object means for controlling and varying the compression of such engines. IVhile it may be employed with any type of reciprocating steam engine, it is especially desirable for use in connection with engines in which the steam enters the cylinder at the end and exhausts through ports in the cylinder covered and uncovered by the piston at or near the end of its working stroke. In such engines where ,these ports afford the only means of-exhaust, it is apparent that the points at which release and compression begin are ixed and nonvariable and since'it is customary to design such engines to give relatively high compression i'or the sake of eiciency, yet such high compression is decidedly objectionable in starting 4and for heavy loads. Where an engine Works under constant load and speed, the events in its cycle of operation may be fixed; but where both speed and -load vary over a wide range, such as in automotive service, itis desirable and is conducive to eiiicient and smooth operation to provide av valve gear that will vary the compression and correlate it with the other events in its cycle of operation, such as lead and variable cut-o.

In carrying out this invention I employ a mechanically operated exhaust or compression control valve and a variable cam for.

operating same, said cam being so shaped that by shifting same axially a variation in the timing and duration of opening, and if desired, the amount of opening, may be varied. I also employ a special ball follower or push rod to facilitate shifting of the camshaft.

Other objects will'appear from the following specification in which my invention is fully described and which is shown in the accompanying drawings, in which Figure 1 is a vertical section on line 1-1 of Fig. 3'; Figure 2 is a similar section on line 2-2 of Fig. 3; Figure 3 is a like partial section on line 3-3 of Figs. 1 and 2;

Figure 4 is a pa-rtial elevation of the camshaft; Figure 51is a section through the exhaust cam 25 on line 5-5 of Fig. 4;I and Fig. 6 is a section of the admission cam on line 6 6 of Fig. 4.

` I have illustrated an embodiment of my as applied to a single acting steam engine, having a cylinder 10, a piston 11,

slidable therein, exhaust ports 37, so located in the walls of the cylinder 10 that 'they' are covered and uncovered by the piston 11 at and near the end of its working stroke. Said exhaust ports 37 open into an annular exhaust cavity 21, cast around the cylinder 10. The cylinder has a compression space 14, which communicates with the steam chest 15, through an inlet port 16, which is normally closed by the poppet admission valve 17, the stem 17a of which is carried in suitable guides and is normally pressed down and held toits seat by the valve spring 18. Steam is supplied through a pipe 15a, leading into the steam chest 15.

The cylinder is provided with an auxiliary exhaust valve or what might be more correctly called a compression control valve 19, which closes the compression relief port 20, which leads from the compression space 14 to the exhaust manifold 21 which communicates with the atmosphere or a condenser through the exhaust pipe 22. The exhaust or compression relief valve -is also provided with a closing spring 18.

The valves are operated by afrotating cam shaft 23, driven in any suitable manner from the crank shaft not shown. The `cam vshaft 23 is provided with cams 24 and 25 for operating the admission and compression relief valves respectively by means of cam followers or push rods 26, as shown in Fig. 3, one of which is shown in partial section in Fig. 1. It will be noted that a ball` 29 is used instead of the usual roller for making contact with the cams. This ball 29 is carried in a sleeve 26a, the lower end of which is reduced suii'ciently to retain the ball, While into its top end is threaded a core 27, having its lower end cupped out concave to form a seat for the ball 29. The threaded core 27 affords an adjustment whereby the ball 29 may turn freely in the lower end of the sleeve and permits adjustment to compensate for any wear between the ball and its seat.. The core 27 is provided with lonitudinal slots 27, adapted to engage the internal end of the spring clip 28, so as to permit lockingthe core in adjusted position. The upper end of the pushA rod 1s provided with the customary adjusting screw 30 'threaded into the `core 27 and provided with The head of this adjusting a locknut 31. j n screw lies just under and concentric with the lower end of the stem ofthe valve 1t 1s intended to operate and permits ready ad# justment in relation to said valve stem. The

'and at the same rotative speed as the crank shaft and of course must be properly timed therewith. The cam shaft is provided with an enlarged end 23 which permits of its being inserted endwise through its bearing. It also has an annular groove 23b intoy which loosely fits a bifurcated member 32 to which is securedA a shiftinvr rod 33. This rod Vmay be controlled in'anyl desired manner to shift the cam4 shaft 23 back and forth axially to vary the valve operation, as will now be explalned. The admission cam 24 has its closure flank 24L cut spirally with reference to the axis of the cam shaft so that this cam is widest at its left end, as shown in Fig. 3, Fig. 4, and Fig. 6, and with this wide end in contact with the valve push rod it is apparent that the admission valve 17 will'have Aa relatively long period of dwell or be held open such a len h of time as to result in a late cut o If the cam shaft is shifted axially toward the left, as viewed in Fio. 3, it is apparentfthat the admission valve operated by cam 24, will close earlier and give earlier periods of cut oif. This will readily be understood by anyone versed in the art, and I do not claim any novelty in the `use of such an admission cam except as used in combination with the variable compression controlling cam here described.

My invention consists, among other things, 1n using avari-able cam for operating the auxiliary exhaust valve or compression control valve, as I prefer to call it. Thiscam has its closure Hank 25a cut s iral ly with respect to its axis, as shown y i25 1nA Figs. 2, 3 4 and 5. It willbe apparent that by shifting such a cam axially., the time of closure of the compression relief valve 19 will be varied and hence the compresslon in the cylinder resulting from the return stroke of the piston will vary. The hftlng flank of this cam may preferably be cut straight and parallel to the axis of the cam shaft, but the closure flank is .cut spirally as shown to give variable time of closure.

i When 'such a compression relief valve and its variable operatingcam are used with engines having exhaust ports 37 covered and uncovered by the piston 11 yat and near the end of its working stroke, it is preferable to so time said cam that its lifting flank will lcause the opening of thecompression relief valve 19, after the exhaust ports 37 arev uncovered by the piston, but if this compression control valve is used with other designs of engines it may be timed to open and cause release at such time as may be desired and may be used as the chief or only exhaust valve on such engines.

As shown in Figs. 3 and 4, the compression control valve operating cam 25 is carried on the same shaft as the admission cam '24 so that the shifting of the cam shaft. will result in a definite correlation,J of compression With the various periods of' out off. 'F or example for starting such an engine or when running under heavy load, the cam shaft would preferably be set in the position of late out off as shown in Fig.

3 and' in. this position the wide face of thev cam for operating the compression control valve would be in action with said compression control valve and would result in relatively low comprsion, but as the engine speeded up or other operative vconditions warranted, the cam shaft could be shifted axially to the left, as viewed in Fig. 3 and Aearlier cut olf couldbe obtained and at the same time the compression would 'be increased. Y

While I have not shown reverse cams, it is understood that these ,may beemployed and that if variable compression in reverse running were desired the same means of obtaining same may be employed.

While I have shown but a single embodi' ment of my invention it is understoodthat it is capable of many more modifications.A

novelty inherent in my invention as broadly as possible, in view of the prior art.

What I claim as new and desire to secure by Letters Patent. is

., A steam engine comprising, in com bination, a cylinder and piston, exhaust ports opened and closed Bly said piston in its travel, a valve controlling an exhaust port at an intake end ofthe cylinder, an intake valve, a rotative and longitudinally slidable cam shaft, cams upon said shaft actuating said valves upon rotation of the shaft, the arc of said camsupon the shaft varying longitudinally of the shaft, and means for sliding the shaft while the engine is running to simultaneously increase or decrease the duration of ladmission of live steam and the duration of the exhaust.

' EARL C. WALKER.

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