US498634A - Steam-engine - Google Patents

Description

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J. DOW.

STEAM ENGINE. No. 498,634. Patented May 30, 1893.

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J. DOW; STEAM ENGINE.

No. 498,634. Patented M y 30, 1893,.

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J. DOW. STEAM ENGINE.

No. 498,634. Patented May 30, 1893.

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.J DOW STEAM ENGINE.

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No; 498,634, Patented May-30,1893.

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J D'0'W.-

STEAMENGINE. No. 498,634. 7 Patented May 30,1893.

I steam chest, taken through one of the oscillatory valves.

' UNITED STATES PATENT OFFICE.

JOSIAH DOIV, OF PHILADELPHIA, PENNSYLVANIA.

STEAM-ENGINE.

SPECIFICATION forming part of Letters Patent No. 498,634, dated May 30, 1893.

. Application filed July 21, 1892. Serial No. 40,814. (No model.)

1'0 all whom it may concern.-

Be it known that I, JOSIAH DOW, a citizen of the United States, residing at Philadelphia, in the county of Philadelphia and State of Pennsylvania, have invented new and useful Improvements in High-Speed Steam-Engines, of which'the following is a specification.

This invention relates to high-speed steam engines of the Corliss type in which the point of cut off is determined by the governor. V

The invention consists in the valve gear mechanism hereinafter described and'then pointed out in the claims.

In the annexed drawings illustrating my invention-Figure 1 is a side elevation of the engine cylinder. Fig. 2 is a vertical longitudinal section of the same showing the steam chest, exhaust chamber and valves. Fig. 3 is a bottom plan of the engine'cylinder. Fig. 4 is a sectional detail view through the line AB of Fig. 3. Fig. 5 is a sectional detail view through the line CD of Fig. 1. Fig. 6 is a central vertical transverse sectionot the engine cylinder, steam chest and the steam inlet and steam outlet. Fig. 7 is a vertical transverse section of the enginecylinder and Fig. Sis a longitudinal section of a cylindrical oscillatory valve. Fig. 9 is a transverse section ofone end of said valve. Fig. 10 is a view of my improved valve gear and wrist plate connections. Fig. 11 is a view of the valve and cutoff-connections with governor attachment. Fig. '12 shows front and side views of the equalizer attachment.

Referring to Figs. 1 to 7, the numeral 1 designates the engine cylinder which is formed with a steam chest, chamber or passage 2 directly under and against the cylinder proper. This steam chest or chamber 2 has on one side of its center a steam inlet 3, entering from below, and with which'a steam pipe can be suitably connected. At each end of the steam chest 2 and below the cylinder 1 is a transversely arranged cylindrical valve-seat at each of which communicates through a port 5 with one end of the cylinder.

The valve 6 is cylindrical and is arranged to oscillate about its axis in the manner of a Corliss valve. Steam does not pass over and around this valve 6 but is admitted into its hollow interioronly at the two ends through an about the ends of the valves, have a steam tight separation from the valve-seats 4, when the valves are in position, by means of packing rings 10, Fig. 7, resting closely around the valves just inside the limits of said chambers.

Each valve 6 hasthroughout its length, on one side and between the packing rings 10, a narrow opening or port 11, Fig. 2, which permits steam to pass through the interior of the valve into the engine cylinder when the opening or port 11 is brought into coincidence with the cylinder port 5, heretofore described; There is also another similar opening 12 through the wall of each valve 6, of about the same dimensions as the opening 11 but on the opposite side of the valve. This opening 12 is the balance port and has cut away from each side seats to hold packing strips 13, Fig. 2, which strips extend the length of the said opening. When steam is admitted into the valve its pressure against these packing strips forces them against their seats and also'against the valve seats 4' in the cylinder casting thereby preventing the steam from passing around the valve. By this construction, also, the excess of pressure at one side of the valve, produced by pressure of the packing strips 13 against the seats 4., serves to hold the valve firmly against its position, will have one side presented to the cylinder port 5 and the other side to an exhaust passage 15 provided in the cylinder casting outside the valve seat, thus forming a channel through which the exhaust steam passes out to an exhaust chamber or passage 16 having an outlet 17, Fig. 6.

It will be observed that the steam chest or main steam chamber 2 covers all the space adjacent to the cylinder 1 between the inner walls of the two valve seats 4, one seat being below each end of the cylinder. The steam chest or chamber 2 is supplied with steam through the inlet 3, entering from below as before mentioned. At each end the steam chest 2 has two passages 9 leadingtothe. chambers 8 through which the valves 6 are supplied with steam. The main steam chamber 2, with its passages 9 and auxiliary steam. chambers 8, is separated from the walls of the exhaust chamber 16 by air spaces 18, Figs.

2 and 6, the whole being by preference cast inone piece. The exhaust chamber 16 is beneath the steam chest 2, as shown in Fig. 2, andhas itsbranches or passages, 15, at each end, curving upward and opening into the outer side of each valve seat. The exhaust steam fromthe cylinder escaping at one of thecylinderports 5passes from either valve pocket-lltthrough one of these exhaust pas-' sages 1,5 into the exhaust chamber 16 whence closing of the port and the necessaryflap are effected; then a still further. movement of the valve is accomplished to bring the exhaust channel orpocket 14 into proper position with relation to .the cylinder port 5 and exhaust passage 15, which position,at the proper time, is',re,versed.to a closing againof the exhaust passage and then on to another presentation of the steam opening 11 to vthe cylinder-port 5 iatpthe beginningof .the nextstroke of the piston 19 in -the engine cylinder. VVhensteam is free .to press directly around and upon a valve of. this general character, thereby-holdingit to'itsseatwith full force, the pressure andconsequent friction are so great as to expose the ,valve to considerable wear, besides requiringthe exertion of a large amount of power-to move the valve. With this valve, however, its outside being isolated from the pressure ofsteam, the excess of pressure at the balance port 12 over that at the opening or port l l, t hrough whichsteam is permitted to pass to the cylinder, is only suflicient to hold the valve closely upon its seat at both steam andexhaustpassages, the latter passage beingkept tight by reason of the peculiar con struction of the valve in which the steam opening 11 and balanceport 12 although nearly opposite each other are yet far enough to the side of a direct line away from the exhaust passage to cause theparallelogram of gtheir combined forces to act sufficiently against the exhaust passage and hold it firmly in place. By a careful adjustment of these conditions in the construction of the valve its whole action is rendered as nearly perfectly balancedas maybe consistent witha firm seat. To'avoid or diminish friction a portion of the outside body of the valve between the steam and balance openings may be slightly cut away.

In Fig. and wrist plate connections through which the vmovements of the valves 6, as hereinbefore described, are accomplished. On the outer end of each valve stem 20, Figs. 5 and 7, is securely fastened an arm 21,Fig. 10, having a pin 22 at its outer end. Attached to and moving .upon this pin22 is one end of a connecting bar 23 the other end of which holds a pin 24 which,either directly or through the interposition ofabloek 25 ,slidesinaslot 26 formed in the outer end of one arm27 of a twoarm ed lever or plate 28 that isloosely mounted on the valvestem 20, or otherwise so supported as to becapable ofv movingfreely about its axis yet without itself communicatingmovement to the valve. The slotted arm 27 is of somewhat greater lengt-hthan the valv e arm21,-as shown in Fig. 10. To.-the short arm 29, of the two-armed lever 28, isp ivotally attached one end of a rod30the otherend'ofwhich is pivotally attached to a wrist plate 31 situated above and midway between the two valves. The two armed lever 28has its hub loosely mounted upon thevalve, stem 20 behind-that of the.Sh0rter valve arm 21 which is-firmly attached to thevalve stem and thusholds-the two-armed lever in place thereon. fl his aiu rangement may, however, be' variedmwithout essential difference inthe action of the parts. Behind the two-armed lever 28 isa grooved cut-off plate 32 having ahub which is also freeto move abontthe axis ofthe valve stem 7 but need not restuponlit. In the construction shown, the outer endof the bonnetf33, Fig. 5, isprovided ,with a bearing 34E forthe hub of said out -off plate. The Tout-off plate 32 is.-provi'ded with-a groove orslot 35 that is concentric with the center of movementof the arms 21,27 and 29 for a large partofits length and in this part holds in proper position the pin 24:, on the connecting bar23 .which pin 24 passes through the slot 26in the arm 27 and into said groove, thereby permitting movementto be given, through thevalvearm 21,.to the valve-6 when the two armed lever 28 is moved. At a proper position on the cut offplate 32 the groove 35 passes by easy transitions to an eccentric are 36 which has its radial center at a distance from the. center of the valve stem 20 exactly equalto that ofthe center of the pin 22 upon the endof thevalve arm. The effect of this arrangement is that as long as the pin 24 upon the connecting bar 23 is held by the concentric part of the groove the valve can be actuated by movement of the slotted arm 27 ofthe two-armed lever 28, but as soon as this pin 24 passes to the are 36 having its radial center coincident to that of the pin 22upon the valve arm, the connecting'bar 23 being of exactly the same length 10 I haveillustrated the valve gear v Ito as the radius of the arc of the groove it' follows that the pin 22 upon the valve arm takes the position of the radial center and onward. This arresting of the movement of the valve is'arranged to take place-just as the valve has received its full opening to the cylinder port 5 where it is, by the means described, held in position until the period for the closing of the valve-for the cut off has arrived; which can be effected simply by moving the'grooved out off plateback sufiiciently, because the pin 22 on the end of the valve arm 21 must remain in the radial center of the are 36 through which the pin 24 on the outer end of the connecting bar 23 is moving; but, to make this movement more positive and avoid all risks of straining the parts or causing lost motion there is placed or formed upon the grooved cut-off plate 32 a spur or projection 37 which may have upon it a cushion 38 projecting immediately behind where the end of the valve arm 2i comes to rest in relation to the cut-0E plate. Upon the said plate being moved back in the path from which the opening movement has come thisspnr 37 presses upon the end of the valve arm 21 and assists tomake sure the closing of the valve. It will, therefore, be seen that upon the movement of the grooved plate 32 depends the cutoff of the steam; consequently it is called the font off plate. Then the cut off plate 32 is moved back-as last described-the pin. 24 on the outer end of the connecting bar 23 may continue to move throughthe grooved are 36 to the end of the movement of the slotted arm 27. When the slotted arm takes its return movement the pin .24 will pass back through the arc and when it reaches the concentric portion of the groove the bar 23 will actagain in drawing the valve arm 21 with it; therefore, if the return movement of the cut off plate were delayed until after thisperiod the slotted arm 27, which controls the main movements of the valve, would of itself, through the connecting bar 23, c ause a closing of the valve in regular course.

The movement of the cut off plate 32 is made independent of the movement of the main wristplate 31 and its connection with the slotted arm. This is accomplished by means of a rod 39 having one end pivotally attached to the cut ofi plate and its other end pivotally connected to a quadrant or auxiliary wrist plate 40 movable upon the same axis with the main wrist plan-a but entirely independent from it.

The main wrist plate 31 receives its motion by means of a rod 41 connecting with the free end of a main rocker arm 42, Fig. 11 which is situated at the side of the engine bed; motion being communicated to said rocker arm through a rod 43fr0man eccentric on the main shaft of the engine, not shown.

Swinging on a pin 44 projectingfrom the upper free end of the main rocker arm 42 is a slotted link 45 to which near its lower end is pivotally attached a rod 46 that is connected to asecond eccentric on the main shaft-- the cut off eccentric}? not shown.

Between the link 45 andthe auxiliary wrist plate 40 is interposed a smaller rocker arm 47, Fig. 11, to the upper or free end of which is pivotally connected one end of a rod 48 the outer end of whichis pivotally connected to a slide block 49 supported in the slot 50 of .the link 45, as shown. rocker arm 47 and directly in line with its Above this second center of movement is pivotally supported the inner or upper end of an equalizer lever 51, vFigs. 11 and 12 which has its arc of movement intersecting that of the rocker arm. Extending the entire length of the outer side of this equalizer lever is a groove 52 in which, either directly, or through the interposition of a block 53 slides a pin 54 which is secured in the end of the rocker arm 47. Through this pin 54 movement is given to the equalizer and by its action in the slide groove 52 all the differences arising. from thearcs of movement of the said rocker arm and equalizer are accommodated. At a fixed point upon the equalizer behind its grooved portion and at such distance from its center of move-. ment that it will, when in motion, intersect the arc of movement of the pin 54 at the outer end of the rocker arm, is placed a pin 55 for attachment of the connecting rod 56 through which movement is imparted to the cut off quadrant or auxiliary wrist plate 40, Fig. 10.

It will be seen that from the main eccentric on the engine shaft, acting through the rod 43, is effected the required movement of the main rocker arm 42 and from it, through the rod 41, movement of the mainwrist plate 31 which in turn by means of the rods 30 in either direction gives movement to'the twoarmed levers 28 which through the connee tions hereinbefore described transmit movement to the valves through all their necessities of action-admissionof steam to the cylinder pause, to await cut off-a taking up of the backward movement at the proper pe riodthe opening of the exhaust-its closing, and then onward to the admission of steam again. i r

The cut off eccentric acting through the rod 46 upon one end of the slotted link 45 while the other end of said link moves withthe free end of the main rocker arm 42 causes sections of the length of the said link from its outer to its inner end-topass successively, at progressive periods of the stroke of the engine, across the out off line, or the posi tion which causes the cut off to be effected; therefore it will be seen that the period when the link slide block 49 carrying its connecting rod 48 will reach the cut off line will be determined by the position of said block in the slotted link 45, a cut off simultaneous with the beginning of the piston stroke being effected when the block 49 is held at or near the outer end of the link, changing through successive periods in the stroke to a position at the inner end of the link, which will effect the latest cut off. These positions of the block in the link are determined by the action of a governor to which the block 49 is connected by means of a swinging bar 58, Fig. 11, which has its upper end attached to a pin 59 upon a slide block 60 which is caused by the governor to move toward and away from the lines of motion of the link, the lower end of said bar 58 being attached to a pin 61 upon the link slide block 49 and the said bar being arranged to pivot freely upon both pins. To support and balance the block 49 with its connecting rod 48 and the swinging bar 58 a weight 62 is connected with and balanced against the slide block 60 to avoid all unnecessary work for the governor which might otherwise arise from gravity of the parts thus supported; yet the greatest delicacy of adjustment is permitted from the action of the governor.

As shown in Fig. 11,the vertically movable slide block 60 may be arranged in a slotted guide standard 63 and is connected with the weight or counterbalance 62 by means of a cord 64 passed over a pulley 65 that is journaled in the upper part of said standard. By means of a system of levers 66, 67 and 68 the slide block 60 is connected with a suitable governor, not shown.

It will be seen that although the link slide block 49' through the peculiar action of the link 45-which is compounded from action of the two eccentricsmay move to a further lateral degree at one position of cut off than at another, the relation of the arcs of movement of the equalizer 51 and its attendant rocker arm 47 is such that the rod 56, connecting with the out off quadrant or auxiliary wrist plate 40, will always receive about the same degree of motion, but being little more than just enough to close the valve and cover the lap necessary; the surplus motion when any is transmitted from thelink 45 being taken up in the rocker arm 47 without materially moving the equ alizcr 51 after a certain distance beyond the intersection of the arcs of motion has been passed. This secures a uniform degree of movement to the cutoff plate 32 with the necessary rapid movement to carry the valve 6 at the time of out off, while thepart of themovement necessary to effect the lap of the valve becomes slower an d slower until a rest is reached; the return movement is progressively the same and simultaneous with the out off for the opposite valve. In this manner quick motion is secured at the moment of cut off, and yet there is an entire absence of any jerk or jar to the parts and only sufticient movement is given to the cut off plate 37 to accomplish the object desired without in any way disturbing its proper relations to the movements ofthe main valve gearing. No matter what the period of cut off, the cut off plate 32 is always reversed in its movement before reversal of the slotted arm 27 takes place and the arc portion 36 of the grooved out off plate is always before the slotted arm 27 until the steam port is opened; and it is again in advance, in reversal, at the 4 time of cut off, until the connecting bar 23 has its pin 24 pass from the are 36 and it then draws the valve arm 21 toward the exhaust opening. 7 V

This valve gear may, without material alteration in construction, be so modified in its use that instead of connecting to only two valves, each having control over admission and exhaust of steam, with cut-off, it may be connected to four valves placed as inthe well known Corliss engine-two at the top of the cylinder for admission of steam and control of the cut off, only, and two at the bottom for the exhaust steam only. In such case the movement from the cut off quadrant or auxiliary wrist plate 40 and its appliances will be applied only to the admission valves while both sets of valves will have their mainmovements from the main wrist plate.

What I claim as my invention is- 1. The combination with a suitable oscillatory valve and a valve arm rigidly secured to the valve stem, of an oscillatory plate or lever loosely mounted on the valve stem, or

otherwise so supported as to be capable of moving freely about its axis, a connecting bar having one end pivotally attached to the outer end of the valve arm and its other end provid-ed with a pin engaged in a slot formed in said oscillatory plate or lever, a wrist plate, a rod connecting the oscillatory plate or lever with said wrist plate, and a grooved cut off plate having a portion of its groove concentric with the valve stem and another portion forming an eccentric are, said groove being engaged with the pin on the end of the connecting bar through which the valve arm is actuated, substantially as described.

2. The combination with a suitable oscillatory valve and a valve arm rigidly secured to the valve stem, of a slotted oscillatory plate or lever loosely mounted on the same axis with the Valve stem, 2; connecting bar having one end pivotally attached to the outer end of the valve arm and its'other end provided with a pin engaged in the slotted portion of said plate or lever, a grooved cut off plate having aportion of its groove concentric with the valve stem and another portion forming an eccentric are, said groove being engaged with the pin on the end of the connectingbar through which the valve arm is actuated and said out off plate provided with a spur projecting immediately behind where the end of the .valve arm comes to rest in relation to the plate, a main wrist plate through which the slotted plate or lever is actuated and an auxiliary wrist plate through which the cut off plateis actuated, substantially as described.

3. The combination with a suitable oscillatory valve and a valve arm rigidly secured to the valve stem, of a slotted lever loosely mounted on the same axis with the valve stem, a grooved cut off plate also loosely mounted on the same axis with the valve stem and having a portion of its groove concentric with the valve and another portion forming an eccentric arc, a connecting bar having one end pivotally attached to'the outer end of the valve arm and its other end provided with a pin passed through the slotted lever and engaged in the groove or cut off plate, a main wrist plate through which the slotted lever is moved to actuate the valve arm according to the required movements of the valve, and an auxiliary wrist plate through which the cut off plate is actuated to control the action of the valve arm independent of the movements of the slotted lever, substantially as described.

4. The combination with an oscillatory valve, its valve gear and wrist plate connections of a rocker arm actuated from an eccenric rod and connected with the wrist plate of the engine valve-gear a slotted link carried by said rocker arm and actuated from the cut ofi eccentric rod, a block adapted to slide in the slotted link and sustained by counterbalance mechanism connected with a governor, and a cut off mechanism connected with and actuated from the said block, substantially as described.

5. The combination with a suitable oscillatory valve, its valve gear and wrist plate connections, a main rocker arm, a swinging slotted link carried by said rocker arm and actuated from the cut ofi eccentric and a block adapted to slide in said link and sustained by counterbalance mechanism, of a second or auxiliary rocker ainn connected with said block, an equalizer lever pivotally supported adjacent to the auxiliary rocker and provided in one side with a longitudinal groove, a pin carried by the auxiliary rocker arm and engaged in said groove, and cut off mechanism connected with said equalizer lever, substantially as described.

6. The combination with a suitable oscillatory valve, its valve gear and wrist plate connections, of a main rockerarm actuated from a main eccentric rod, a rod connecting one end of said rocker arm with a main wrist plate from which the valve is actuated, a swinging slotted link carried by the main rocker arm and actuated from the out 01f eccentric rod, a slide block supported in the slotted link and connected with a governor, a second or auxiliary rocker arm and main wrist plate, a rod connecting the said auxiliazy rocker arm with the link slide block, an

equalizer lever pivotally supported adjacent to the auxiliary rocker arm and having a varying connection therewith, and a rod connecting said equalizer lever with a cut otf quadrant or auxiliary wrist plate through which is actuated a cut off plate that controls the action of the valve gear, substantially as described.

7. The combination with an oscillatory valve, its valve gear and wrist plate connections of a main rocker arm actuated from a main eccentric rod and connected with the main wrist plate of the engine valve gear, a swinging slotted link carried by said main rocker arm and actuated from the cutoff eccentric rod, a vertically movable slide block supported in a slotted guide standard and provided with a counterbalance weight, a link block adapted to slide in the slot of the swinging link and connected with said vertically movable slide block by means of a swinging bar, a governor connected with the slide block, a second or auxiliary rocker arm intermediate the main rocker arm and main wrist plate, a rod connecting said auxiliary rocker arm with the link slide block, an equalizer lever pivotally supported adjacent to the auxiliary rocker arm and having a varying connection therewith, and a rod connecting said equalizer lever with a cut off quadrant or auxiliary wrist plate through which is actuated a cut off plate that controls the action of the valve gear, substantially as described. 7

8. The combination with a suitable oscillatory valve, its valve gear and wrist plate connections, of a main rocker arm actuated from a main eccentric rod and connected with the main wrist plate, a swinging slotted link car- 7 ried by the main rocker arm and actuated from the cut off eccentric rod, ablock adapted to slide in the slotted link and controlled by a governer, a second or auxiliary rocker arm connected with said block and located intermediate the main rocker arm and main wrist plate, an equalizer lever pivotally supported adjacent to the auxiliary rocker arm and provided in one side wit-h alongitudinal groove engaged with a pin carried by said auxiliary rocker arm, and a rod connecting said equalizer lever with a cut off quadrant or auxiliary wrist plate through which is actuated a cut ofi plate that controls the action of the valve gear, substantially as described.

' In testimony whereof I have hereuntoset my hand and aftixed my seal in presence of two subscribing Witnesses. I

JOSIAH DOW. [L. s.] Witnesses: H. B. LUFFBERRY, J. W. RADcLIFFE.

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