US470863A - Edward p - Google Patents

Description

(No Model.) 3 Sheets-Sheet 1.

E. P. COWLES. OUT-OFF MECHANISM FOR STEAM ENGINES. No. 470,863. Patented Mar. 15, 1892.

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3 Shets-Sheet 2.

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E. P. OOWLES. OUT-OFF MECHANISM FOR STEAM ENGINES.

Patented. Mar. 15, 1892.

WITNESSES:

NORRIS FEYEIS co., moroan'nm, wwnmuwn, 0. c4

(No' Model.) a Sheets-Sheet 3. E. OOWLES. GUT-OFF MECHANISM FOR STEAM ENGINES.

PatentedM ar. 15, 1892.

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was en, Prim-011mm, WASHINGTON n c luv-11 EDNVARD P. COVVLES, OF NEWV DECATUR, ALABAMA.

CUT-OFF MECHANISM FOR STEAM-ENGINES.

SPECIFICATION forming part of Letters Patent No. 470,863, dated March 15, 1892. Application filed August 1'7, 1891. Serial No. 402,797. (No model.)

- To aZZ whom it may concern.-

Be it known that I, EDWARD P. OOWLES, a citizen of the United States, residing at New Decatur, in the county of Morgan and State of Alabama, have invented certain new and useful Improvements in Out-Off Mechanism for Steam-Engines, of which the following is a specification. I

This invention relates to an improvement in cut-off mechanism for steam-engines. It

is herein illustrated as applied to the style of compound engine shown and described in an application for patent, Serial No. 376,940, filed by me January 7, 1891, but is also applicable to other forms of engines.

The invention is illustrated in the accom panying drawings,in Which Figure 1 shows a side elevation of the engine provided with my improved cut-off mech anism. Fig. 2 shows atop or plan view with parts broken away and parts shown in section. Fig. 3 is an enlarged sideyiew of the cut-off mechanism. Fig. 4 is an end view of the same. Fig. 5 is a transverse vertical section on the line 5 5 of Fig. 2. Fig. 6 is an enlarged detail sectional view illustrating the construction of the cut-off valves and ports. Fig. 7 is a diagram representing the relative movements of the piston and valves in double expansion. Figs. 8 and 9 are detail views showing my improved cut-off applied to common slide-valves.

As before stated, my invention is herein shown applied to a compound engine of the type described in my former application. In this engine the steam-chests 5 are located at opposite ends of the cylinder 11, and in them work the two slide-valves 32, which are suitably connected together, so that they operate as one valve. Bolted to the flange of the rear valve is a rearwardly-extending yoke or saddle 50, to which are secured rearwardly-extending hollow stems 51, which are located onopposite sides of the piston rod 15, and are formed with forked ends which have grooves in their extremities, as shown at47. (See Fig. 2.) Through these stems pass rods 52, which are attached to and work a cut-off valve 53, which, together with the openings or ports it closes, are shown in detail in Fig. 6. These rods are also provided with bifurcated ends 48, the purpose of which will be hereinafter stated.

At the rear end of the rear valve 32 is, as shown in Fig. 2, a wall perpendicular to the line of travel of said valve, and within this wall are formed the annular openings 54, which admit steam to the inside of the valve and leave bars 55. The cut-off valve is of the same form as this wall, and its bars correspond with and serve to close the openings or steam-ports between the bars of the said wall. At the forward end of the forward valve is a similar wall and cut-off valve, and the cut-off valves are connected together by means of rods 59, which are secured to radial arms 58, connecting together the bars of the cut-off valves and extending beyond the slide-valves to permit their connection with the rods 59, thus forming practically one valve. These rods are of sufficient length to allow play be tween the cut-off valves and the open'wallsof the slide-valves. alternately to open and close the ports, or, in other words, when the cut-off ports at one end of the engine are open those at the other end thereof are closed.

The slide and cut-oft valves are operated by the following-described mechanism: 40 designates a rock-shaft, which is operated by means of the arm 44 and eccentric-rod 45,'located outside of the bed-plate, as is usual. This rock-shaft is provided with depending arms 46, which are located in pairs on opposite sides of the piston-rod 15, as shown in Fig. 5. The lower ends of these arms are pivoted to the forkedends 47 of the hollow stems 51. The rock-shaft is cast hollow, and through it passes a shaft 60, which is provided with depending arms 61, located between the arms 46 of the rock-shaft, and pivoted at their lower ends to the rear extremities of the rods 52, which rods are, as hereinbefore stated, formed .or provided with bifurcated rear extremities for the reception of the ends of said arms. The shaft is also provided with an arm 62, which extends parallel with the arm 44 of the rock-shaft and, like said arm, is located be yond the outer surface of the bed-plate of the engine. From the foregoing it will be readily understood that any movement of the arm 62 with respect to the arm 44 will move the cut- The cut-off valves operate off valve 53 with respect to the slide-valve 32 within the rear steam-chest, and that when said rods move together or in unison no such movement of the cut-oif valve will result.

In view of the fact that with the above-described construction there is no room for the usual connection between the stems 51 and rods 52 and the arms 46 and 61, and that it is necessary to accommodate the are described by said arms in operation, the rock-shaft is supported in vertically-movtble bearings 63 by arms 64, the said bearings sliding in brackets 65 on the engine-frame.

The mechanism for operating the cut-off valves is supported by a block or frame 70, (see Figs. 3 and 4,) which is movable in guides 71, formed on a bracket 7 2,.attached to the engine-frame. This block is connected to the arm 44 of the rock-shaft by means of a rod 73, so that in operation it has the same horizontal movement as the eccentric-rod 45.

74 designates an eccentric crank or cam, which is provided with a pin 75, forming its axle. This pin has its hearings in the block or frame 70, and it extends outward therefrom toward the eccentric-rod 45. Any movements of the eccentric crank or cam 74 will be transmitted to the cut-off valves by a rod 84, connecting said eccentric and the arm 62, moving said valves with respect to the slidevalves 32 and opening or closing the ports in the walls of said slide valves as the horizontal motion of the pin 75 coincides with that of the pivot-pin 7 6 of the arm 44; but when said eccentric is stationaryitwillfirmly resist any motion of said cut-off valve with respect to the slide-valve.

The eccentric -cam 74 is formed or provided with a hub 77, which in shape is like a frustum of a cone, and located outside of this hub and centered on the pin 75 thereof is a pinion or segment of a pinion 78, the inner surface of which is cupped to fit said coneshapcd hub. A spring 200, Fig. 2, is located outside the pinion 78, which spring, when compressed by a nut on the end of the pivot-pin 75, will force the cones together and both against the block or frame 70. The friction between the cones is greater than that between the eccentric-cam and the block or frame, and thus when the pinion 78 turns it will carry the eccentric-cam and also the cutoff valve with it until said cutoff valve is seated, when further movement of said eccentric-cam ceases and the cones slip the rest of the movement of the pinion or segment of a pinion. It will therefore be seen that the initial movement of the pinion in either direction opens or closes the cut-oif, and that the balance of its movement is consumed by the slip-joint formed by the hub of the eccentrica crank and the cup of the pinion.

Intermeshing with the teeth of the segment of a pinion 7 S is a rack 81, which slides vertically in guides formed on the block or frame 7 O. This rack carries an isosceles triangle 82 on the side opposite said pinion, the perpendicular bisecting line of which is at right angles to the line of travel of said rack 81. More or less of the transverse motion of the eccentric-rod 45 is transmitted to this rack by means of a pin 83, provided with a hub 84, sliding on a square or feathered pin 85, projecting inwardly from said eccentric-rod, the degree of motion depending on the position of the pin 83 with respect to the apex and base of the triangle 82, as is obvious.

It will be readily understood that the abovedescribed mechanism for operating the cutoff valves is automatic in its action, and that by utilizing the transverse motion of the eccentric-rod no extra parts are or need be introduced, as the movement of said eccentric-rod approximates closely to that of the high pressure piston, the transverse motion of said eccen trio-rod being peculiarly adapted to the use to which it is put from the fact that it is the lap of the valve in advance of the said piston. A movement of five thirtyseconds of an inch of the cut-off valve gives a large clear openin As the ports of the cutoff mechanism take steam from both sides, as shown by the arrows in Fig. 6, the valve is required to travel only one-half the width of the port to open or close the same.

In the present instance the cut-01f port is practically twenty-six feet long, and a movement of five thirty-seconds of an inch gives forty-eight square inches of opening. The throw of the eccentric 74 is two inches. The diameter of the pitchcircle of the segment of a pinion 78 is three inches, so that obviously a movement of one-fourth of an inch in the rack 81 closes the cut-off valve. The pin S5 is located at such a point in the eccentric-rod 45 as will give a positive motion, and at the same time will not render the connections 73 and 84 too cumbersome. In the present case the main eccentric 100 has a throw of three and one-half inches, and the pin 85 is placed where it will have a vertical movement of two and one-half inches. Hence the pin 83 has the same vertical movement, and it therefore takes an angular advance of thirty-five degrees of the main eccentric to close the cutoff valve.

The triangle 82, herein above described, has a width at its base sufficient to allow the pin 83 to have a play equal to its vertical travel less the movement necessary to close the cutoff valve, which in this case is two and onefourth inches. At the apex of this triangle said pin fits closely to the sides of the latter.

The operation of this cut-off will be fully understood from the foregoing, taken in connection with eccentric diagram, Fig.7. This diagram islaid off with the eccentric circle full size, having a diameter of three and one-half inches,which also represents the piston-stroke, whichistwenty-fourinches,thedivision-marks indicating inches of the piston-stroke. The crank is represented as traveling in the same circle as the eccentric center. The pistonvalve 32 has a lap of seven-sixteenths of an inch and a lead of one-sixteenth of an inch, giving alinear advance of one-half inch, thus placing the eccentric center at the point marked 101 when the crank is on a dead-center at 102. Suppose the pin 83 to be at the apex of the triangle 82. The cut-off would commence to close when the eccentric center was at 103its lower mid-position-or before the piston reached the end of its stroke. It would close when the eccentric center had traveled up thirty-five degrees from said mid-position or to the point marked 110, at which time-the crank would be at 104 and the piston at 105. Steam would thus have followed the piston only three-fourths of an inch. Supposing the pin to be at the base of the triangle 82, the cut-off would remain open until said pin had traveled across to the opposite side of the triangle, or until the eccentric center had reached the point marked 106, thirty-five degrees below 107,which designates the upper mid-position of the eccentric center,'and the said cut-oft would be closed as the eccentric center traveled from the point 106 to 107 while the crank is travelin g from the point marked 108 to 109. Valve 32 cuts off when the crank is at 109 and the.

piston at 110. Thus steam would now have followed the piston twenty-two inches. It is obvious that by moving pin 83 from one end of the triangle to the other the cut-off can be made to take place at any point between three-fourths of an inch and twentytwo inches. It is further obvious that in no case does the piston travel more than two and onehalf inches during the cut-off movement, which is practically instantaneous.

The slide-pin S3 is connected to an angle lever 86, which is pivoted to the bracket 72 by means of a rod 88, having ball-joints. The short horizontal member of this angle-lever is connected to a governor 89, which may be of the ordinary and well-known construction and which is situated upon the bracket 72. When this pin 83 is disengaged from the sides of the triangle 82, the slightest force exerted upon it will be sufficient to cause it to slide on the pin 85, thus rendering it extremelysensitive and capable of responding to the slightest change of speed. When the pin 83 engages the sides of the triangle 82, it binds on this feathered pin 85, and further movement of the pin 83 will be prevented thereby. The

eccentric crank or cam is made sufficiently large, and there is sufficient friction between it and the box or frame of the automatic cut-off gear to prevent any movement of it by the force applied to 84:- As before stated, the rod 88 has a balland-socket connection with the angle-lever 86 and sliding pin 83, which serves to accommodate the circular motion of this rod 88 toward the eccentricrod 45. As said rod 88 describes an are, it causes a slight oscillation of the angle-lever 86, which oscillation would disturb the action of the governors. To overcome this disadvantage and to permit the governor to operate while the pin 83 is engaged a double-act- &:c., is not changed by the variation of cutoff; During the movement of the cut-off valve 53it is exposed to full steam-pressure on each of its sides, and it will therefore be perfectly balanced. The combined area of the cutoff ports being greater than that of the steam ports the current of steam through said outofi ports during admission is very slight, and what there is acts in the direction in which they are to move. Then the cut-off valve closes, expansion begins both in the slidevalve in the rear steam-chest and in the highpressure cylinder, so that the pressureoutside is greater than on the inside, and the cutoff valve will be held firmly to its seat until said slide-valve closes the ports leading to the high-pressure cylinder. The power required to operate said cut-oft valve is therefore very slight and its action is certain.

In Figs. 8 and 9 is exhibited the construction in which the cut-off mechanism is applied to common slide-valves, Fig. 9 being an automatic and Fig. 8 a permanent cut-off. Referring first to Fig. 9, it will be observed that the bars between the cut-off ports 54 are located outside and that the cut-off valves are connected by means of distance-bolts 158, which are similar to the connecting-rod 43, Fig. 2, on the sides of the valve 32. The hollow valve-rod 57 is slotted to receive and accoinmodate a key 159, which passes through the cut-01f rod and the hub on the cut-off. This key serves to couple the cut-off rod to said hub, in order that it will be able to work the cut-off valve. It is operated by gear similar to that already described in connection with the valve 32. In the construction shown in Fig. 8 the bars 55 between the cut-off ports are located inside instead of outside, as invthe other constructions, and the cut-off valves 53 are connected together bya sleeve 161,through which the valve-rod passes, the said valve-rod being secured by a set-screw 160. It acts as a valve-yoke, moving up to the cut-off ports, alternately cutting off steam and then shoving the valve along before it. The first return movement of the valve-rod closes the cut-off whichever way it may be moving.

I do not wish to be understood as limiting myself to the precise construction herein set forth, as many modifications thereof will suggest themselves to persons skilled in the art. For example, the triangle 82 could be secured directly to the pinion 78, thus dispensing with the vertically-sliding rack 81; but such construction would be objectionable, in that the triangle would have a rolling sliding motion on the pin 83. The are described by the pin is so short that it is practically straight, so that it substantially coincides with the said rack in its vertical movement, and the contact of pin 83 and the triangle 82 is positive.

It is also obvious that the slip-joint 77 can be of many forms and placed anywhere between the triangle and the valve-stems. Again in a single-cylinder engine with a common slide valve provided with a cut-off, as modified in Figs. 8 and 9, the steam-chest could be placed on one side, as is commonly done, and the hollow stem 57 and cut-oil stem extending therethrough could lead directly to the automatic device and the rocker (shown in Fig. 5) be dispensed with.

It will be understood that the only use of the rockerand accessories is to oltset the motion of the eccentric and automatic device in engines constructed to require it. There are also many ways of coupling the hollow stem 57 and the cut-off stem extending thereth rough to the valves besides those shown. It is also obvious that the triangle 82 and sliding pin 83 can be of many forms and arranged in many different ways without materially altering the principle.

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent, is

1. In a steam-engine, the combination of a cylinder, a piston and piston-rod operating therein, a steam-chest communicating with said cylinder, a slide-valve operating in said steam-chest and having a wall perpendicular to its line of travel and provided with ports to admit steam into the slide-valve, a cut-ott valve of similar form to said Wall and adapted to close the ports of the latter, and mechanism for operating said valves.

2. In a steam-engine, the combination of a cylinder, a piston and piston-rod operating therein, a steam-chest communicating therewith, a slide-valve operating in said steamchest and controlling the entrance of steam to the cylinder, a cut-ofl? valve controlling the entrance of steam to the slide-valve, suitable connections between the latter and the eccentric-rod of the engine, an auxiliary eccentricrod for operating the cut-oil valve, an eccentric for said rod, and suitable connectio11s between said eccentric and the main eccentricrod of the engine, whereby the transverse movement of the latter actuates the eccentric and shifts the cut-oil.

3. In a steam-engine, the combination of a cylinder, a piston and pistonrod operating therein, a steam-chest communicating therewith, a slide-valve operating in said steamchest and controlling the entrance of steam to the cylinder, a cut-off valve controlling the entrance of steam to the slide-valve, suitable connections between the latter and the eccentric-rod of the engine, an auxiliary eccentricrod for operating the cut-01f, an eccentric for said rod having an extension in the form of a frustum of a cone, a pinion cupped to fit said extension and spring-actuated to have frictional contact therewith, a rack engaging said pinion, and suitable connections between said rack and the main eccentric-rod of the engine, whereby the transverse movement of the latter actuates the said rack and consequently the pinion and eccentric and thereby the auxiliary eccentric-rod and cut-01f valve.

4. In a steam-engine, the combination of a cylinder, a piston and piston-rod operating therein, a steam-chest communicating therewith, a slide-valve operating in said steamchest and controlling the entrance of steam to the cylinder, a cut-elf valve controlling the entrance of steam to the slide-valve, suitable connection between the latter and the eccentric-rod of the engine, an auxiliary eccentricrod for operating the cut-elf valve, an eccentric for said rod having an extension in the form of a frustnm of a cone, a pinion cupped to fit said extension and spring-actuated to have frictional contact therewith, a rack e11- gaging said pinion and having a triangular frame, and a pin engaging the latter and connected to the main eccentric-rod of the engine, whereby the transverse movement of the latter actuates the rack and consequently the pinion and eccentric and thereby the auxiliary eccentric-rod and cut-oil valve.

5. In a steam-engine, the combination of a cylinder, a piston and piston-rod operating therein, a steam-chest communicating therewith, a slide-valve operating in said steamchest and controlling the entrance of steam to the cylinder, a cut-oil? valve controlling the entrance of steam to the slide-valve, suitable connections between the latter and the eccentric-rod of the engine, an auxiliary eccentricrod for operating the cut-cit, an eccentric for said rod having an extension in the form of a frustum of a cone, a pinion cupped to fit said extension and spring-actuated to have frictional contact therewith, a rack engaging said pinion and having an isosceles triangle, a pin secured to the main eccentric-rod of the engine and projecting therefrom, and a sec- 0nd pin mounted on said first pin and engagin g said isosceles triangle, for the purpose set forth.

6. In a steam-engine, the combination of a cylinder, a piston and piston-rod operating therein, a steam-chest communicating therewith, a slide-valve operating in said steamchest and controlling the entrance of steam to the cylinder, a cut-oit' valve controlling the entrance of steam to the slide-valve, suitable connections between the latter and the eccentric-rod of the engine, an auxiliary eccentricrod for operating the cut-01f, an eccentric for said rod having an extension in the form of a frustum of a cone, a pinion cupped to fit said extension and spring-actuated to have frictional contact therewith, a rack engaging said pinion and having an isosceles triangle, a pin secured to the main eccentric-rod of the englue and projecting therefrom, a second pin mounted on said first pin and engaging said isosceles triangle, and suitable connections between the said second pin and the governor of the engine.

7. In a steam-engine, the combination of a triangle orits equivalent mounted on a block connected to and. moving in unison with the purpose of operating the cut-off variably, subro valve or eccentric-rod and connected to the stantially as shown and described. cut-off valve by a slip-joint, and a pin sliding In testimony whereof I affix my signature in with reference to the bisecting line of the trithe presence of two Witnesses.

5 angle under control of an enginegovernor and having the transverse motion of the ec- EDWARD P. OOWLES.

centric-rod engaging said triangle laterally Witnesses: and transmitting a portion of the transverse A. J. GREEN,

motion of the eccentric t0 the latter for the H. L. BROWN.

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