US1056115A - Valve-gear for fluid-pressure engines. - Google Patents

Description

A. G. MUMFORD & A. ANTHONY. VALVE GEAR FOR FLUID PRESSURE ENGINES. APPLICATION FILED APR. 29, 1912.

1,056,1 15. Patented Mar. 18, 1913.

FIG. I.

WITNESSES INVENTORS (LTPW flaMumford. y Ann/thong Attorney COLUMBIA PLANOGRAPH co., WASHINGTON. 0 c4 UNITED STATES PATENT OFFICE- ARTHUR G. MUMFORI) AND ALFRED ANTHONY, OF OOLGI-IESTER, EN GLAND.

VALVE-GEAR FOR- FLUID-PRESSURE ENGINES.

To aZZ whom it may concern:

Be itknown that we, ARTHUR GEORGE ltlrmrono and ALFRED Axrrroxy, subjects of the King of Great Britain and Ireland, and respectively residing at The Culver Street Engineering IVorks, Oolchester, in the county of Essex, England, and Beaconsfield avenue, Colcheste-r, in the county of Essex, England, have invented certain new and useful Improvements in Valve-Gear for Steam and other Fluid Pressure Engines, of which the following is a specification, reference being had therein to the accompanying drawing.

This invention relates to the valve gear of fluid pressure engines of the direct-action type, 27. c. the type in which the reciprocating action of the piston is imparted direct to the purpose for which the power is required without the intervention of a crank or its equivalent, and it relates particularly to that type of direct-action engine in which the main distributing slide valve is operated by a shuttle piston valve which receives its motion partly from the piston rod of the engine and partly from the pressure of the fluid employed to drive the engine.

In valve gears of the type specified the exhaust ports which put the ends of the shuttle valve cylinder into communication with the main exhaust are controlled by the shuttle valve, and consequently during a large portion of that part of the travel of said valve, which is effected by the piston rod of the engine, said valve is moving against the full pressure of the steam.

The object of the present invention is to balance this pressure so as to minimize the force required to move the shuttle valve during that portion of its travel when it is receiving motion from the piston rod of the engine, whereby greater smoothness of working is attained and the durability of the working parts is materially enhanceda Ive attain this end by controlling the exhaust ports of the shuttle valve cylinder both by the shuttle valve and by the slide valve, so that communication between the ends of said valve cylinder and the main exhaust is only established at that end toward which the shuttle valve is traveling, that is.

to say, when it is required to effect the reversal of the valve by fluid pressure.

In the accompanying drawing which illustrates this invention :-Figure l is a Specification of Letters Patent.

Application filed April 29, 1912.

Patented Mar. 18, 1913.

Serial No. 693,856.

broken view in longitudinal section of the improved valve gear adapted for a steam engine, Fig. 2 is a view in plan, and Fig. 3 is a view in transverse section on lines a" a: Fig. 2.

Throughout the views similar parts are marked with like letters of reference.

The shuttle valve 64, which is of the usual construction, is mounted in a cylinder Z) which is preferably made in one with the steam chest 0. The slide valve (Z, which controls the main admission ports 6 c and the main exhaust port f, is operated by the shuttle valve (4 by means of a strap piece 9 carried by said shuttle valve which alternately engages first one end and then the other end of a recess 61 in the back face of the slide valve so as to permit of a certain amount of lost motion between the valves. The shuttle valve a is operated by a rod h which receives a positive motion from the piston rod 01' other reciprocating part of the engine through any suitable mechanism. This Valve rod h is not fixed to the valve (4 but passes freely into it and carries a collar 71 at its back end which works in a recess a at the back end of the valve so that the valve has a limited amountof free movement relative to the rod.

In the ends of the shuttle valve a are small L-shaped ports Z and Z which put the ends 6 and b of the valve cylinder alternately into communication with the steam chest 0 and with the exhaust ports m and m These exhaust ports instead of communicating directly with the main exhaust port 7 are connected by passages m" with ports m and m located in the face of the seating (Z of the slide valve (Z on either side of the ports a and f. In the slide valve (Z are two ports 0 and 0 which run between the face of the slide valve (Z and the exhaust cavity 6Z thereof. These ports are so arranged that at predetermined periods during the travel of the slide valve in either direction they place the ports m and m in communication with the main exhaust port f through the exhaust cavity (Z of the valve.

The action of the valve gear is as follows :-Assuming the two valves a and (Z to be in the position shown in Fig. 1, the forward end 6 of the valve cylinder is in communication with the steam chest 0 by the port Z so that the pressure in said end of cylinder is the same as that in the steam chest 0 and the other end. 6 of the valve (When the 'alve he valve (Z, has moved in the toe :i1'l0\v'-1l1l(l8l the influence ol the l'flll fle-so l'ar that the port Z registers with the port m, the port 7212 registers with the passage 0, and the port 5 opens to the steam chest .1; the steam pressure in the back end oil the valve cylinder causes the shuttle valve to contii'iue its :liorward motion which in not opposed by the pressure o'l'f he steam in the front end o t the 'alve cylinder as the trout end. 7f of said cylinder open to the i rain exhaust port j by the ports Z, m, m" and o, and by the exhaust cavity (Z of the. va ve d. llurtl'icr movement of the two 'alves (i and (Z in the direction of the arrow ta the port 0 out of i ister with the port w thereby shutting oil the main exhaust poi-t from the front end. Z) of the valve cylinder, and so causes the valve to come to rest. "the slide valve (Z having now opened the rear admission port c, the valve rod h commences to more in. the opposite direction to the arrow and in due time its enlarged end 72, contacts the other end of the recess a and causes the shuttle valve o to move with i s the port Z open to the steam chest 0 lo stea 1 pressure in the back end 6 of the cvlinder opposed to the movement of u ttle v lve, but as the front end 6 of i v cylinder is notopen to the main st f,

by reason of the ports a and 0 not registering, the pressure of the fluid. in

iacl; endi Zf oi the valve cylinder is bal- 3y the pressure oi the steam leaking i-astthe forward end of the valve into the forward end 0 of the valve cylinder. l ur- 'tliEl' movement of the 'alve a on its return stroke-which brings the ports m and 0' into register takes the port Z out of register with the passage m so that there is still no communication between the front end If of the valve cylinder and the main exhaust port j".

li hat we claim as our invention, and desire to secure by Letters Patent i 1. n a valve gear for steam or other fluid pressure engines, the combination with a main slide valve controlling the adm sion and er; ust ports of the engine, of a cylinder in c nmunication with. the steam chest containing the slide valve, a piston valve 0" the shuttle type working in said cylinder, a

coupling between aid valves whereby the 1,oac,115

shuttle valve operates the slide valve with a predeter nined amount of lost motion, means for imparting motion to the shuttle valve with a predetermined amount of lost motion, ports in the ends of the piston shuttle va ve cylinder leading to the slide valve lace, ports in the ends of the piston shuttle valve for establishing connmmieation between the ends of said cylinder and the steam chest and the ports leading from the ends of the piston shuttle valve cylinder to the slide valve taco I'CSPCCtiYQlY, and ports in the slide valve for establishing communication between the ports in the slide valve taco and the exhaustcavity of said valve, as set forthv 2. in a valve gear tor steam or other fluid pressure engines, the combination with a main slide valve controlling the admission and exhaustports of the engine, of a cylinder in communication with the steam chest containing the slide valve, :1 piston valve oi? the shuttle type woriting in said cylinder, :1 coupling between said valves whereby the shuttle valve operates the slide valve with t predetermined amount of lost motion, means for imparting motion to the shuttle valve with a predetermine l amount of lost motion, an exhaust port in each end ot the piston shuttle valve eyiinder-said ports leading to the slide valve face and opening thereto on either side of the main admission and e:'- haust ports of the engine, ports in the ends ot the piston shuttle "alv-e for establishing comi'nunication between the ends of the piston shuttle valve cylinder and the steam chest and the exhaust ports of the shuttle valve cylinder respectively, and ports n the slide valve for establishi communieation betw-en the exhaust ports in. the slide valve face and the exhaust cavity of said valve, as set forth.

3. li a device of the character described, the con'ibination of a slide valve, a steamchest containing said slide-valve, a piston *alve oi? the shuttlelyme, a coupling; between said. valves, said coupling having," a sliding connection with said slide valve and a Fixed connection with said piston-valve, and a piston rod having a sliding); connection with said piston-valve, said piston valve and said slidevalve having;- ports alternately establishing commimication through the steam chest ports vith the respective ends oft the pistonwalve chamber, and the exhaust chamber of the slide-valve.

4;. In a device of the character descril'ied, the combination of a SllClY llVQ, a steamchest containing said slid-ovalve, a piston valve 0; the shuttle-type, having a chainbered end, a piston rod received by said piston-valve, and having a headed end received within said chambered end of the pistonvalve, and a coupling between said slidevalve and said piston-valve said coupling having JIQCl connection with Said piston names in the presence of subscribing Witnesses.

A. G. MUMFORD. A. ANTHONY.

\Vitnesses:

A. H. \VYATT, F. NOBLE.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents Washington, I). C.

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