US833582A - Valve-gear for steam-engines. - Google Patents

Description

W/TNESSES.' I:

c. W. CRAWFORD. VALVE GEAR RoR STEAM ENGINES.

APPLICATION FILED JAN. 24, 19 06.

PATENT-ED. 00E. 16, 190s.

1HE Nanms PE1-:Rs co., WASHING-@2.11, n:A

No. 833,582. y PATENTBD OCT. 16. 1906.

G. W. CRAWFORD.'

VALVE GEAR Foa STEAM'BNGINES.

APPLIOATION FILED JAN. 24, 190B.

2 SHBETS-SHEET 2.

vor other steamgenerator.

UNITED STATES PATENT OFFICE.

VALVE-GEAR FOR STEAM-ENGINES.

Specicatonof Letters Patent.

Iatented Oct. 16, 1906.

Application led January 24, 1906. Serial No. 297,585.

To- @ZZ whom it Wha/y concern:

Be it known that I, CHARLES WESLEY CRAWFORD, a` citizen of the United States, and a resident of Brazil, in the county of Clay and State of Indiana, have invented a new and Improved Valve-Gear for Steam- Engines, of which the following is a full, clear, and exact description.

The invention relates to valve-gears for steam-engines, such as shown anddescribed, for instance, in the application for Letters Patent of the United States, 270,092, filed by me July 17, 1905.

The object of the present invention is to provide a new and improved valve-gear for steam-engines arranged for producing reduced clearance, silent action of the valve when running the engine at a high rate of speed, quick positive opening and closing of the valves, and keeping the same stationary when closed. y

The invention consists of novel features and parts and combinations of the same, which will ybe more fully described hereinafter and then pointed out in the claims.

A practical embodiment of the invention is represented in the accompanying drawings, r

forming a part of this speciiication7 in which similar characters of reference indicate corresponding parts in all the views.

Figure l is a side elevation of the improvement. Fig. 2 is an enlarged longitudinal central section of the same, and Fig. 3 is a plan view ofthe rocking cams for the levers employed for holding the admission-valves to their seats against the pressure of the steam.

The cylinder A of the engine is mounted on the engine-bed B, and in the said cylinder A reciprocates a piston C, having its piston-rod C' connected with a cross-head D, mounted to slide on suitable guideways arranged on the engine-bed B, and the said cross-head D is connected by a pitman E with the crankarm F of the main driving-shaft F, journaled in suitable bearings carried by the engine-bed B. The cylinder A is provided at its ends with admission-ports a and b and with exhaust-ports c and d, of which the admission-ports a and t open into a steamchest G, connected by a pipe G' with a boiler The exhaustports c and d open into an exhaust-chest II, from which leads an exhaust-pipe H' for conducting the exhaust-steam from the engine to a suitable place of discharge. The admis- Serial No.v

with the main shaft F, so

sion-ports@ and b are adapted to be closed and opened by valves I and I', arranged to be seated on the said ports from within the steam-chest G, and the stems I2 and I3 of the said valves I and I are connected with pistons I4 and I5, mounted to reciprocate in auxiliary cylinders J and J opening at their inner open ends into the steam-chest G, as plainly shown in'Fig. 2, so that steam-pressure is at all times against the under side of the said pistons I4 and I5 to move the same outward, thus moving the valves I and I their seats through the medium ofthe pressure of the motive agent, or, in other words, the valves I and I are moved into an open position by the pressure of the motive agent.

The valves I and I are rovided with hollow trunks I6 and I7, exten ing through stuffing-boxes J2 and J 3, held on the heads J4 and J5 of the cylinders J and J for closing the outer ends thereof. Through the trunks I6 and I7 extend pins K and K, outer ends on set-screws K2 and K3, screwing in the ends of rocking levers L and L', fulcrumed at L2 and L3 on brackets L4 and L5, attached to the steam-chest G. The rocking levers L and L are recessed at their outer yends for the reception of the outerends ofthe pins K and K', as indicated to the left of Fig. 2.` The rocking levers L and L' extend toward each other, and'their inner or adjacent L" in peripheral engagement with cams N and N', of which the ycam N is secured on a shaft N2 and the cam N' is secured ona sleeve N3 is journaled in suitable bearings arranged on brackets N4, attached to the steam-'chest G, and on the forward ends of the shaft N2 and the sleeve N3 are secured armsO and O', connected by links O2 andV O3 with 'a wristplate P, mounted to turn on a stud P', arranged on the cylinder A.

On the wrist-plate l? is secured a wrist-pin,

connected with a rock-l, ,t n, at Q2 on the engine- "n, l

P2, engaged by a link Q ing lever Q', fulcrumed bed B, and the said rocking-lever Q is connected by a link Q2 with the link-block Q4 of a link-motion, having the usual link lQ5 engaged by an eccentric Q6, secured to the main driving-shaft F ofthe engine. The link-block Q4 is pivotally connected by a link vQ with a lever Q8, connected with the up-and-downsliding member R of a centrifugal governor R, connected byga suitable .transmission R2 N2, held loosely on the shaft N2. ,The sleeve ends are provided with friction-rollers L6 and j ythat when the eni c pins K4 and K5, seated at their inner ends on the valves S and and at their outer ends on set screws K and K7, held on rocking levers V and V, fulcrumed at V2 and V3 on brackets V4 and V5, attached to the exhaust-chest H. The inner or adjacent ends of the levers V and V are provided with friction-rollers V6 and V7 in peripheral contact with the arms Wl and W2 of a cam W, ysecured on a shaft W4,l journaled in brackets W5, attached to the exhaust-chest H. I On the forward endof a Vsla/'aft W4is secured a crank-arm W, connected by al link W7 with a rocking lever W2, fulcrumed on Athe lpin Q2, previously mentioned, andthe said rocking lever W8 is connected bya link W, with the upper end of the link lQ5 lof the linlk-niot'ion above referred to. Thus when Ithe. engine is running and the linklQ5 is rocked it imparts a rocking motion to the lever W8, which by the link W7 and crank-arm Wrocks the shaft W4 and the cam so that lthe arms 'and W2 thereof act onfthe friction-rollers and V7 to rockthe tlevers V'and Vlto cause the pins K4 and .K5 to movethe'exhaust-valves S and S inwardly into a closed position 'Ind to hold the same ina closed position forthe proper length of time-'that is,th e exhaust-valves S positively closed by mechanical gine is running the governor R is actuated, said trunks extend the and by the movable member R and the lever Q8 and link Q7 an up-and-downsliding motion is given to the link-block Q4, according to the speed of the engine to regulate the rocking movement of the Wrist-plate P, which by the connection above described causes sooneror later closing of the valves I and I.

lWhen the engine is running, the wrist-plate Piscaused Ito rock, so that a rocking ,motion is given to theishaft N2 and sleeve N alto rock the cams N and N ,which bytheir connection withthe friction-rollers L6 and L7 cause arocking of theleversiL and L', so that the latter by the-pins K and K forcibly move the valves I and Iy U0 :their seats with a view to close the portsa and bas'longas the friction-rollers L6 and L7 are in peripheral contact with the cams N and N The latter are ,so arrangedthat when Iit is desiredl to lopen the valves IandvI then: the friction-rollers L6 ,and L7 ltravel off the ends of, the cams and N toallow the pressure of thestelam Within the chest G to act on the corresponding pistons I4 and I5 to move the Isameoutward with a view to unseat the, valves I ,andI -that is, to open the corresponding,.admiSSiQIkpOrt a 01 5 fOr ddmission zof* steam` from theA chest G into,the corresponding endof theycylinder Thus by! thez arrangement described. the` valves .I and IA areopened by pressure ofthe motive @gestand areblosed. by mechanical .CQnbrivances,underthe control of the governonR. Thevalvers I and I, their stemsI2 and I2, and Jistons, I4 and I? Aare provided Iwith by-passes 1 tand I, vto v,allow steamA to kpass from the closedy end of,` the cylinders J andJ to the under sidesof the valves I and I ,thus permitting proper working ofthe pistons I4 and I5 inthe said cylindersJ and J. e y

, The exhaust ports c and d areyadapted to be closed and Opened by valves S and S', @O11- nectedbytheir stems S2 and S3 with pistons S4 and S5, having enlarg'edouter ends ISs and S7, ,and mountedto slide inauxiliary cylinders T and Tf, attached to theexhaust-chest H vand opening attheir inner open ends intoy the said chest H., ,Liive `steam is .admitted into the auxiliary cylinders T and Tv` by pipesr U and U connected with ya boiler or other suitable source of steam-supply, so that the pressure ofthe steam, acting against theenlarged heads S and S7 of the pistons S4 and S5, forces the same outwardly to move the valves S and S olfl their seats, or, in other words, the exhaustvalves S andSf are moved into openpositions by pressure of live steam. I The heads ,T2 and T? for closing vthe outer ends of the auxiliary cylindersT andT are provided with drainpipes .U2 and U3 for carrying off any water of condensation inthe lower outer ends of the auxiliary cylinders T and T.

vyThe,exhaust-valves S and S are provided with hollow trunks 7S8 `and S, extending through the headsT2 and T3, and through the and S are means, but,- are opened bypressure of live steam, before mentioned. Itis understoodthatwhen the cam W is rocked'andftlie friction-roller VGforV7 asses overl tlie endof its corresponding arm 1, or W2into `anotch W3 between the Ladj acent cam-arms W and 2, then thevexhaust-valve yS or S. isreleased of the pressure by the mechanical means to allow the live steam'actingl onthe pistons S6 and S7 tomove the exhaust-valves S and S into an open position.A As thelink Qiisn'niformly rocked by the eccentric Qu ofthe main` shaft F, it evident that aregularl closing and o -eningof the exhaustvalves S and Stakes p ace`,while the closing of theadmission-valves vI and I takes place sooner or later,l according to :the speed of theA engine andowing to the action of the governor R on thelink-motion, as previously explained, ,p

yThe operation is as follows: When the several parts are in the positions illustrated in Fig. 2,,then the Qvalves'I" ,and S are held in a closed position by the mechanical means previously described, whilethe valves I and S are held in an ,open position by the action of the motive agent on the pistons I4 vand S, vas above explained. The motive agent from the steam-chest G now passes by way of the port a into the outer end of the cylinder vA and actsv on the piston C therein .to push the latter von its inward stroke inthe direction of the arrow a, it being understoodl that during this movement of thewpistfon C thelink-motion causes the cams N'and N t`o'rock, so that the valve I positively closed, to cutoff the steam at the desired length in the stroke IOO IIO

of the piston In a like :manner the valve is closed when the piston C reaches the end of its stroke, and then the valve I is opened by the pressure oi the steam from within the steam-chest G, while the valve-S is opened by pressure of the live steam on the pistonSi. The motive agent in the steam-chest G now passes by way of the port l) into the inner end oi the cylinder A to act on the piston C therein with a view to send the piston on the return or outward stroke in the reverse direction ofrthe arrow a. The cylinder-heads A and A2 of the cylinder A are provided adj acent to the ports a, c and b d with recesses or cut-out portions A3 Af and A5 A, respectively, of which the recesses A3 and A4 are adapted to be engaged by offsets C2 and C3, formed on the outer face of the piston C, and the recesses A5 and AG are adapted to be engaged by offsets C4 and C5, formed on the inner face of the piston C. By the arrangement described the piston C when moving into an outermost position, as shown in Fig. 2, moves, with its offsets C2 and C3, into the recesses A3 and A4, thus reducing the clearance-space between the piston C and the cylinder-head A to a minimum, and in a like manner when the piston C moves to the end of its inward stroke then the offsets C1 and C5 pass into the recesses A5 and A3. Thus in either case the clearance between the piston C and the corresponding head A or A2 is reduced to a minimum, and at the same time i'ull provision is had for a full passage of the steam into the cylinder A by way oi the ports a and b and the corresponding recesses A3 and A5. In a like manner a complete unobstructed exhaust is had from the cylinder A by way of the recesses A4 and A5 and the ports c and d whenever the valves S and S are opened.

It is understood that the valves I and I are in the form of puppet-valves having rigidly attached thereto to balance the valves, and the latter are also provided with a trunk or auxiliary piston open at the outer ends to the atmosphere for the purpose of providing an upward pressure when the valves are open. It will also be noticed that, owing to this upward pressure after the valve is opened the latter is perfectly balanced, and it requires but the trunk area to gain sufiicient pressure to hold the valve open forcibly against its lever and cam to prevent noise.

Having thus described my invention, I claim as new and desire to secure by Letters Patent- 1. A valve-gear for steam-engines, coinprising a cylinder, a steam-chest connected by admission-ports with the ends oi the said cylinder, admission valves adapted to be seated on the said ports and each having a reduced trunk extending to the outside oi the said steam-chest, admission-valve pistons connected and moving with the said admission-valves, auxiliary cylinders openpistons ing at their inner ends into the said steamchest and in which reciprocate the saidl admission-valve pistons, the pressure of the steam exerted against the said admissionvalve pistons causing the latter to move to open the admission-valves by the pressure of the steam, rocking levers having loose connections with the said valves by way of the said trunks, independent rocking cams in engagement with the said levers to move the admission-valves to their seats and to allow the valves to open by pressure of the steam against the said pistons, a `wrist-plate connected with the said cams, and a link-motion connected with the said wrist-plate for rocking the same.

2. A valve-gear for steam-engines, comprising a cylinder, ahsteam-chest connected by admission-ports with the ends of the said cylinder, admission valves adapted to be seated on the said ports and each having a reduced trunk extending to the outside of the said steam-chest, admission-valve pistons connected and moving with the said admission-valves, auxiliary cylinders opening at their inner ends into the said lsteam-chest and in which reciprocate the said admissionvalve pistons, the pressure of the steam exerted against the said admission-valve pistons causing the latter to move to open the admission valves by the pressure of the steam, rocking levers having loose connections with the said valves by way of the said trunks, independent rocking cams in en agement with the said levers to move the a mission-valves to their seats and to allow the valves to open by pressure of the steam against the said pistons, a wrist-plate connected with the said cams, a link-motion connected with the said wrist-plate Jfor rockin the same, and a governor controlling the said link-motion. C

3. A valveear for steam-engines, comprising a cylin er, an exhaust-chest connected by exhaust-ports with the ends of thel said cylinder, exhaust-valves adapted to be seated on the said ports and having trunks extending to the outside of the said exhaustchest, exhaust-valve pistons connected and moving with the said exhaust-valves, auxiliary cylinders containing the said exhaustvalve pistons and connected with a source oi live steam Jfor the latter to move the pistons to open the said exhaust-valve by steampressure, and mechanical means engaging the said valves by way oi the said trunks to move the pistons and the exhaust-valves inward against the pressure oi the live steam and to seat the said exhaust-valves.

4. A valve-glear for steam-engines, comprising a cylin er, an exhaust-chest connected by exhaust-ports with the ends oi the said cylinder, exhaust-valves adapted to be seated on the said ports and having trunks extending to the outside of the said exhaust- ITO ohest,^eXl1-`austvalverpistons connected and lnovi'ng with the said leXh'aust-valves, auxiliary cylinders `containing the said exhaustvalve pistons land connected with a source of live steamffo'r the latter to move the pis'- vtons 'to kopen thesaid exhaust-valve bylsteampressure, levers having a loose connection 'with the said 'valves by way of the said trunks, and a `rocking 'earn in engagement with the said levers to move the said exhaustvalves to their seat-s and to `allow the said exhaust-valves to 4open by Epressufr'e of the steam lexerted against the lsaid :exhaustvalve pistons.

5. A valve; vear for `steainengines, born'- prising a eylin er, an eXhaust-ohest-conneetedby exhaust-ports with the ends of the said cylinder, exhaust-valves adapted to fbe seated on the said ports 'and having :trunks eX- tending to `the outside ofthe saidexhaust'- lchest, exhaust-valve pistons 'connected and moving with 'the said exhaust-valves, :auxiliary cylinders -eonftaining lthe said 4exhaustvalve pistons :and connected with .a source of live steam yfor -the .latter 'to move the pistons to lopen the said exhaust-valve by steampressure, levers having a loose connection with the `said vvalves by way of the said trunks, fa rocking bam Ehaving arms, vand a recess between the said arms forengagement by the said levers to move 4the said 'exhaustvalveslalterna'tely to their seats and yto allow the lsaid Yexhaust-valves to open alternately yby'the pressureof the'steamexerted against 'the said :pistons :In testimony whereof I have signed my 'name `to this speeieation in the presence of 'two subscribing witnesses.

CHARLES l'WESLEY CRAWFRD. Witnesses:

DAVID H. MORGAN, A. C. -LANAGAN

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