US398014A

US398014A - Trip-valve gearing

Info

Publication number: US398014A
Authority: US
Publication date: 1889-02-19
Anticipated expiration: 1906-02-19

Description

( No Model.) 2 Sheets'-Sheet 1.

W. M. WHITLOGK.

TRIP VALVE GEARING. No. 398,014. Patented Feb. 19, 1889.

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M. WHITLOOK.

TRIP VALVE GEARING.

Patented Feb.- 19.- 1889.

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\YILBUR M. \VHITLOCK, OF NEIVARK, NEIV JERSEY.

TRIP-VALVE GEARING.

SPECIFICATION forming part of Letters Patent No. 398,014, dated February 19, 1889.

Application filed October 11, 1888- Serial No. 287,840. (No model.)

To all whom it may concern..-

Be it known that I, WILBUR M. W HITLOCK, a citizen of the United States, residing at Newark, Essex county, New Jersey, have in vented certain new and useful Improvements in Trip-Valve Gearing, fully described and represented in the following specification and the accompanying drawings, forming a part of the same.

The object of my invention is to adapt the Corliss valve-motion to use in engines provided with piston-valvcs, and to obviate the use of separate stem-chests and separate valves at the two ind uction-ports and the two eductionports of the cylinder. By my construction a single steam-chest is used and two independent balanced piston-valves are arranged and operated to admit the steam to and discharge it from the cylinder with the same effect as the four valves used in the Corliss engine. I employ the same trip-motion and the same governing devices as have long been used in the Corliss engine, and which are already understood, and I connect each of my pistonvalves with an independent latch for tripping it at-the desired point in the stroke, and render such point variable under the control of the governor, as in other engines. The valve is actuated by a rock-shaft, with which it has a positive connection, and is formed of two cylindrical heads or pistons of slightlydift'erent diameters, between which is a space in constant communication with the exhaust.

The steam is admitted to the opposite end of each piston-valve to substantially balance it, and one of the pistons operates to cut off the steam from the induction-port, while the other piston serves to compress the steam in a dashpot or compression-chamber provided for the purpose to produce a reaction and shut off the steam automatically when the valve is released by the cut-off mechanism at any desired point in the stroke. The larger area upon one end of the valve operates, when employed, to develop a resistance to the move ment of the valve when it has wholly closed the induction-port The invention will be understood by rcferonce to the annexed drawings, in which Figure l is a side elevation, and Fig. 2 a plan, of a steam-engine cylinder and chest provided with my attachments. Fig. 3 is a view of the outer side of the chest. Fig. 4 is a longitudinal section of the chest on line a; as in Fig. 1. Fig. 5 is a longitudinal section of the chest and part of the cylinder on liney y in Fig. 1. Fig. 6 is an enlarged view of the eccentric-arm, rocker-arm, and latch. Fig. 7 is an enlarged longitudinal section of one of the balanced valves in section on line y y in Fig. 1. Fig. 8 is a sectional view of the same on line 2 z in 7, and Fig. 9 is a view of part of the chest shown in Fig. 5 with the valve shifted to open the induction-port.

A is the steam-cylinder, and B the valvechest, the heads being omitted from both. The valve-chest is provided with a steam-supply pipe, B, which delivers the steam into a passage, C, from which it is conducted to the opposite ends of the chest through passages C, and thus delivered to cylindrical seats I), in which are formed annular cylinder induction and eduction ports 6. At the middle of the chest, in line with the seats D, are formed two dash-pots or compression-chambers, f, furnished each with a steam-inlet, g, at some distance from their dividing-partition h.

Intermediate to the seats D and chambers f exhaust-apertures i are formed in one side of the chest adjacent to the cylinder A, and connected by passages J with the exhaustnozzle K upon one side of the cylinder A. Two piston-valves are fitted to the chest, each consisting in a steam-cut-ofl' piston, Z, and a compression or dash-pot piston, Z, connected by a cylindrical shank, which is shown formed with annular teeth m, to constitute a rack for the application of a segment, or, to shift the I valve. Each segment is secured to a separate rock-shaft, 0, and the annular teeth at permit the valve-pistons-to turn in their seats, and thus equalize the wear.

The rock-shaft may be oscillated by any suitable cutoff mechanism adapted to open the valve during the required part of the stroke and to thenrelease it, after which the compression of the steam in the dash-pot f operates to shift it automatically and close the steam-cylinder port 6.

The piston Z is the true valve which opens and closes the port 6, which serves both for vnduction and eduction, and when set outside IOC when the piston Z is central over the port, as

shown in the same iigure.

The steam in the dash-ptiuf is therefore unable toescapc when the piston Z is moved by the cutoff mechanism to open the induction-port, and develops by compression a resistance upon the piston Z, which operates,

when the cut-off mechanism releases the' valve, to immediately throw the piston 7 over the port 0 and close it, as desired. 13y forming the seat D and piston l a little larger than the piston Z the pressure upon the piston Z is or may be made greater than that upon the piston l, aml as soon as the piston 1 passes the steam-inlet g, when moved automatically by the steam compressed in the chamber f, the difference of live-steam pressure upon the piston 7 becomes operative and arrests the movement of the valve and holds it normallyin its central position. (Shown in Fig.

The operation oi' the piston Z in the chambcrfisthe same as that of the plungerin any form of dash-pot, and permits the free movement of the piston or valve Z until the piston or plunger I passes over the hole g. The steam in the dash-pot then becomes compressed and serves to return the valve to its central position as soon as it is tripped by the cut-oil. mechanisn'i, which will be hereinafter described. It the compressed steam in the dash-pot possessed too high a tension when the valve was tripped, it might throw the valve over the port c with too great force or velocity, and thus open the exhaust. To check the movenuznt of the valve when thrown to its middle position is the object of making the piston l a. little larger than the plunger Z, so that when the live steam presses upon both the difference of. pressure will operate to arrest the moving valve; but I have also provided a means to prevent any excess of pressure in the dash-potj", and thus regulate the velocity of the valves returi'i movement within the required limits. Such means consists in a relief-valve, n opening from the chamberf i nto the li ve-steam space, and held to its seat by a regulated spring, a so as to open when the pressure of the steam compressed in the dash-pot exceeds a certain amount. By making the pistons l and 1 to vary in area one square inch and giving the relief-valve a an area of one inch it is obvious that the pressure operative upon the piston l to oppose the valve 1 to its neutral position would never exceed the actual tension of the spring '11", as the valve u" would be opened when such tension was exceeded by eon'i 'iression in the dash-pot.

The means shown [or moving the valves and tripping the same when supplying steam to the ports 6 is shown herein similar to that used in certain Corliss-valve steam-engines; but a peculiar modification is made to enable the same mechanism to actuate the same valves during the exhaust ot' the steam from the same port,

Each valve is connected by the toothed segment a positively with its rock-shaft 0; but such shaft is unlike the rock-shaft:- of Corliss valves in general clutched to the eccentricrod of the engine during the exhaust half of each stroke, and is thus moved positively ontward from the dash-pot during the first half of the exhaust-stroke to connect the port e with the exhaust-aperturc 2 and positively inward during the last half of the exhauststroke to close the port 6 and set the valve in readiness to take steam at the beginning of the working stroke of the en gine-piston. Such clutching mechanism consists partly of the cut-off latch and partly of a dog or key on the rock-shaft, arranged to engage with the cocentric-arm just at the time the latch is caught, but in an opposite direction, so that the dog and latch together hold the rock-shaft i from turning in either direction, and connect it positively with the eccentric rod or arm. The dog, like the latch, engages with the sh ai't when moved in only one direction and affords a free movement in the opposite direction, and the rock-shaft is thus free to turn backward when the cut-off latch is tripped to per mit the dash-pot to shift the valve, as desired, to cut off the steam.

The operation of these devices is shown in Figs. 1, 2, 3, and (5, a being the cut-cit latch, P the eccentric-rod, P the eccentric-arms applied to turn loosely upon the rock-shafts o, and b the catch upon the arm P ,With which the latch a engages, Each latch. is pivoted to a crank-arm, 0, attached rigidly to the end of the shaft 0, and the valve Z is thus moved with. the latch a whenever the latter is aetuated. Disks E are pivoted upon the shafts 0, and are formed upon their peripheries with raised seats s, to detach the latches a from the catches bat the proper point in the steamstroke, and rollers c are provided upon the outer ends of the latches to operate withsuch raised seats, as is common in Corliss engines. Springs o. press the rolls upon the disks. The disks E are properly linked together by a bar, I, and are held in the required position to trip the cntoti' latches a by a rod, 1, which would be actuated by a suitable governor.

The dog is shown as a key, '1', fixed in the shaft 0, and operatii'ig in a wide keyway, r, formed in the hub of the eccentric-arm P, to permit lost motion in one direction, as per arrow i in Fig. 6, when the latch a. is tripped.

The arms P are moved regularlyback and forth by the eccentric-rod 1, (being connected by a link, P and the wide keyway aiiords a loose connection in one direction between the arm P and the crank c, carrying the latch, to

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permit the backward movement of the latch, as per arrow 6, and the valve-piston Z, when actuated by the pressure in the dash-pot f, while the rod P is moving in the opposite direction, as per arrow it. On the return-stroke of the rod P, when it is moved as per arrow u in Fig. 6, the valve is held in its neutral position by the pressure upon the pistons Z and Z, as shown in Fig. 4-, until the arm P reaches its middle position, (shown in Fig. 6,) the keyway r turning freely over the keyway r in the shaft 0 until the side of the kcyway strikes the edge of the key. The latch a engages the catch 1') at the same time as the key engages the side of the keyway, and the crank c is then looked to the arm P in both directions. The valve thereafter moves in unison with the eccentric-rod, and the piston lis carried back and forth during the exhaust-stroke of the engine working-piston the same as a plain slide-valve The valve also opens to supply steam to the working-piston under the control of the arm P, and moves in unison with the eccentric-rod P until the latch a is tripped by the seat 8.

From the above description it Will be seen that I have devised a valve which is as readily tripped for cutting off the steam as any Corliss valve, but, unlike any Corliss valve, is moved positively to open the exhaust, and by the same latch and eccentric-arm also. I thus make two valves operate as effectively as the four valves ordinarily used in Corliss engines, and secure the same free exhaustand the same facility for regulation. It is obviously immaterial how the dog operates to engage the eccentric-arm P upon the side opposite to the latch a, and instead of the key 0' and wide kcyway r a circular plate may be attached to the shaft o'and slotted to fit a pin projected from the side of the arm P. The slot in such case would permit the play in one direction the same as the wide keyway r, while the pin could strike the end of the slot with the same effect as the key r operates. 1

It is also immaterial, so long as balanced 1i)lStOl1\'1lVPS are used, whether the dash-pot be located inside the valve-chest or not, as it is already common to attach the dash-pot plunger for closing the cut-off valve to the 1 r sage intermediate to each of the said comcrank-arm c, that carries the latch (1.

Having thus set forth my invention, what I I claim herein is 1. A cylindrical valve having one end ap plied to an annular cylinder induction-port and the other end fitted to a compressionchamber provided with a steam-inlet in its side to introduce the steam under pressure, and the induction-port and the steam-inlet being arranged in relation to the valve so that the steam-inlet is closed as the induction-port is opened, as and for the purpose set forth.

2. A cylindrical valve having one end applied to an annular cylinder induction-port, an opposite end of smaller diameter fitted to a compression-chamber provided with a steaminlet in its side, a rock-shaft for shifting the valve to open the induction-port and compress the steam in the compression-chamber, and cut-off mechanism to release such rockshaft at a suitable point, substantially as herein set forth.

3. A cylindrical valve having one end applied to an annular cylinder induction-port and the other end fitted to a compressionchamber provided with a steam-inlet in its side to introduce the steam under pressure, and the induction-port and the steam-inlet being arranged in relation to the valve so that the steam-inlet is closed as the induction-port is opened, and an outlet-valve from the 001111)IQSSlOil OhfilllbBl to limit the pressure therein, as and for the purpose set forth.

4. A cylindrical valve having one end applied to an annular cylinder induction-port and the other end fitted to a compressionchamber provided with a steam-inlet in its side to introduce the steam under pressure, and the induction-port and the steam-inlet being arranged in relation to the valve so that the steam-inlet is closed as the induction-port is opened, a passage leading from the compression-chamber through the pistonvalve, and a relief-valve seated upon the outer side of such passage, as and for the purpose set forth.

5. The combination, with a steam-cylinder valve-chest, of two cylindrical compressionchambers in the middle of the chest with steam-inlets in their sides, two cylindrical valve-seats with annular inductiolrports near the ends of the chest, a steam-supply to such valve-seats and steam-inlets, an exhaust-passage intermediate to each of the said compression-chambers and valve-seats, and two valves provided at their opposite ends with pistons fitted, respectively, to such chambers and valve-seats, the whole arranged and operated substantially as herein set forth.

6. The combination, with a steam-cylinder 'alve-chest, of two cylindricalcompressionchambers in the middle of the chest, with steam-inlets in their-sides, two cylindrical valve-seats with annular induction-ports near the ends of the chest, a steam-supply to such valve-seats and steam-inlets, an exhaust-paspressionchambers and valve-seats, two valves provided each with pistons at their opposite ends, and with an intermediate shank having a rack formed thereon, and rock-shafts provided with segments to reciprocate such valves, and cut-off mechanism for actuating such rock-shafts, substantially as herein set forth.

7 In a steam-engine, the combination, with a port operating as an induction and eduction port, of a piston-valve fitted thereto and connected with a rock-shaft, an eccentric-arm fitted loosely upon said shaft, a dog to engage the arm in one direction and a crank-arm attached to the shaft and provided with a latch to engage the arm in the opposite direction, i In testimony whereof I have hereunte sei; and mechanism for t-rippingthe latch, as and n1 y hand in the presence of two subscribing T0 for the purpose set forth. Witnesses. V

8. In a Steam-engine,theconlbinntion,with i VWILBUR 3L rHITI-OCK 5 a balanced nston-valve, of: a steam dash-pot and a relief-valve discharging from the interior 01 such dash-p01; into the steam-space of valve-chest, as and fur the purpose set forth.

\Y i t nessesr THos. S. CRANE,

i F. FISCHER.