US645789A - Valve-motion for engines. - Google Patents

Description

Patented Mar. 20,1900. E. E. CLARK.

VALVE MOTION FUR ENGINES.

(Applicatmn filed Jan. 25. 1899.) 3 Sheets-Sheet l4 (No Model.)

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3 Sheets--Sheet 2 (No Model.)

Patented Mar. 20,1900.

3 Sheets- Sheet Ej. E.' CLARK.l vALyE Mo'TluN Fon ENGI'NES.

(Ap'pucariun mea Jan. 25,'1a99- (No Model.)

Nieren STATES PATENT rricn.

EZRA E.l CLARK, OF SPRINGFIELD, MASSACHUSETTS.

VALVE-MOTION FOR-ENGINES.

SPECIFICATION forming part of Letters Patent No. 645,789, dated March 20, 1900.

Application filed January 25, 1899. Serial No. 703,354. (No model.)

To @ZZ whom it may concern.-

Be it known that I, EZRA E. CLARK, a citizen of the United States, residing at Springfield, in the county of Hampden and State of Massachusetts, have invented an Improveinent'in Valve-Motions for Engines, of which the following is a specification.

This improvement is especially adapted to duplex engines that are employed to drive pumps by a direct action. In pumping-en'- gines of this character it has been usual to employ two rock-shafts, one of which is moved by a connection to the cross-head of one engine and the other is moved by a connection to the cross-head of the other engine, and there are arms upon the respective rock-shafts and connecting links and rods to the valves ot' the engines, so that the first engine and its rock-shaft give motion to the valve of the second engine and the second engine and its rock-shaft give motion to the valve of the first engine. These engines being well known do not require further detailed description. vIn engines of this character diiculty has been experienced in making use of a cut-olf for working the steam expansively, and the present valve-motion is especially adapted to operating cut-oft valves for the duplex engines. I make use of a compound lever intervening between the cut-offs and the rock-shafts, whereby the compound lever gives motion to the cut-off by the combined action of the two rock-shafts, and the motion given by the compound leverto the respective cut-offs is adapted to work in harmony with the valve-motions of the respective engines.

I make use of a lever that is pivoted at or near the middle upon a fixed support. One end ot this lever is connected to a crank-arm on one of the rock-shafts, and the other end of the lever is connected to and forms the pivot of the secondary lever, and the other end of this secondary lever is connected to the crankarm of the other rock-shaft, and at or near the middle ot the secondary lever is a connection to the cut-otf-valve rod, so that the rst rock-shaft gives its motion through the primary lever, swinging the secondary lever upon its connection to the second rock-shaft, and thereby moving the valve of the cut-oft, and the crank of the second rock-shaft, acting upon the secondarylever, gives motion to the l rod of the cut-oft, and in this case the end of the primary lever becomes the pivot of the secondary lever that is moving the cut-off, and where the pivots are central upon the primary and secondary levers of the cut-off both ends of the two levers have the same motion corresponding, or nearly so.

In connection with the aforesaid compound lever, composed of a primary and secondary lever, I arrange the steam passage-ways leading to the valves of the respective engines in such a manner as to employ two cut-oft' valves upon one valve-stem and in this way use one compound lever for the two engines; but the compound lever and its action is the same, regardless 'of the peculiar steam-passages or any peculiarity of cut-od valve.

In the drawings, Figure l is a vertical lonand representing the valve-stem and the compound lever thereof and a portion of the connections to the rock-shafts. Fig. 2 is a plan view of Fig. 1 with the cover of the chest of the cut-od valve removed. Fig. 3 is an elevation representing the manner in which the steam-pipes may be led to the cut-ott chest. Fig. 4 is a sectional elevation,looking in the direction of the piston-rods of the respective engines, representing the manner in which the steam-passages are led and also showing by an elevation the compound lever; and Fig. 5 is a diagrammatic illustration of the respective motions given to the cut-ott rod.

The cylinder A is usually known as the right-hand engine and the cylinder B as the left-hand engine, and these when used with a pump are provided with piston-rods that extend to the pistons of the pump-cylinders, and each engine has its own valve, which is of any desired character, and the valve-rods are represented at C and D. When the two engines are arranged so that the cutoff devices are upon one stem, -I find it advantageous to provide the steam-supply pipe E with athrottle-valve F, and below the throttle-valve F the steampipe branches to the side throttle-valves G and H, by which the as to adjust the power according tothe resistance to the movement of the piston. The

pipes I and I lead from the side throttle-valve 'steam can be regulated to either engine, so-

length of swing and the cut-olf receives a gitudirial section through the cut-oit valvesv IOO to the cut-off-valve chest K, within which is a partition 5, by which the cut-off-valve chest is divided into two parts, and the ports 6 and 7 lead, respectively, to the steam-pipes L and M, the steam-pipe L leading to the valve-chest of the engine A and the steam-pipe M leading to the valve-chest of the engine B.

` The rock-shaft N receives its motion from a connection' to the cross-head of the engine A, and the rock-shaft O receives its motion from a connection to the cross-head of the engine B, and upon the rock-shaft N is a crank 7 to the valve-rod D of the engine B, and on the rock-shaft O is a crank 8 and connection tothe valve-rod C of the engine A, so that the valve of the engine A is moved by the engine B and the valve of the engine B is moved by the engine A. These parts, however, are well known in duplex pumping-engines and do not require further description, as my improvements hereinafter described are available with this class of pumpingengine or with any duplex engines where there are two rock-shafts and their connections for moving the valves.

The cut-oft rod P passes into the cut-off chest K through a suitable gland or stuffingboX 10, and the cut-ott' valve R is over the port 6 to the engine A, and the cut-o valve S is over the port 7 to the engine B, and the valve R is solid, but preferably formed with stead yin g-feet 1l, and the valve S is made with a central opening 12, and it is advantageous to make use of nuts 13 and 14 on the cut-oit rod P between horns upon the respective valves, there being a greater space between the horns than the thickness of the nuts, so that there may be a play or lost motion of the cut-ofE-yalve rod in acting upon the cut-off valves. The valve-rod P passes through a sleeve or gland in the partition 5.

The primary cut-off lever T is pivoted at 15 and is provided with a link 16 toa crank-arm 17 on the rock-shaft N, and the secondary cut-off lever U is provided with a link 1S to the crank-arm 19 on the rock-shaft O, and the secondary cut-o lever is pivoted at its upper end 2O to the pri marycut-off lever T, and the secondary cut-off lever is connected to the cut-ott rod P, and it is advantageous where the action of the cut-oit is to be adjusted or varied to employ a lost-motion link 2l, as represented, `for varyin g the distance between the center of the secondary lever U and the respective cut-ott valves, so that they may act sooner or later, and with this object in view the link 21 is made with a sliding block for the pin on the secondary lever and screws 22 Within the slot in the link 2l, so as to hold the block in either position to which it may be adjusted within' said link.

The action of the cut-oft' valves is as follows: In ordinary duplex engines there is a slight pause at the en d of each stroke for the the ends of the strokes of the engine, and hence the primary and secondary cut-o levers receive a motion coinciding with the inotion of the rock-shafts, and usually the rightthat is given to the cut-01T rod is governed by the movements of the rock-shafts, and the cut-oft valves are made with reference to the movements thus received and to the cutting off at the proper times, andi remark that the sizes and shapes of the cut-off valves for the respective engines may vary according to theV location of those valves and the respective action of them. In consequence of one cutoff valve being solid and the other with a central opening the cut-off valve R moves from the position of Fig. 1 and acts to close the port 6 and cut ofi? the steam passing to the cylinder A in order that it may work expansively, and in so doing the motion of the valve-rod yP carries the cnt-off S past the port 7, so as to open such port 7, and then the further motion of the cut-otE-valve rod closes the port 7 and simultaneously opens the port 6 by the valve R passing beyond it, leaving the port 7 closed, with the steam cut oi to the cylinder B. The valve-rod P now commences to move in the opposite direction; but it does not give motion to either Valve until the respective nuts have moved between the horns and come into contact with the opposite side. At this time the valve R returns over the port 6 and cuts oi the steam to the cylinder A and then continues to exclude the steam from the cylinder A as the further motion causes the valve S to open the port 7and admit steam to the cylinder B, and then the continuation of the motion of the valves in the same direction cuts oft the steam through the port 7 to the cylinder B and opens the port 6 to the cylinder A, andthe port 7 to the cylinder B remains closed until the valves and rod are moved in the opposite direction to repeat the operation and cut oft the steam by the port 6 and open the steamway to the port 7. In these operations the valve-rod P and valves are moved first in one direction and then in the other and receive their full stroke; but one engine gives to the cut-0E i valves about half of the travel, and then the other engine takes up the motion and 'continues the same to the end of the stroke, and similar motions are given in the return stroke in the other direction, and it is to be borne in mind that each ordinary enginevalve determines the time at which the steam is admitted, regardless of the cut-od, the cutoff only acting to exclude the steam from the valve-chest at the predetermined point in the stroke, and it is therefore only necessary to adjust the cut-off valves with reference to acting at the proper time in cutting off, and I remark that when the valves are properly set and proportioned, as described and illustrated, the time for the action of the cut-off will be varied by adjusting the distance between the valves and the connections of the valve-rod P to the secondary cut-off lever U by the screws 22, as aforesaid, and I remark that in consequence of this improvement being especially adapted to pumping-engines there is practically no difficulty in effecting this adjustment, because usually it is necessary to maintain the pressure in the respective cylinders during from live eighths to seven-eighths of the stroke.

I have represented steam-pipes and the cutoff-valve chest as adapted to a pumping-engine where the steam-pipes can be led to the cut-o valve chest with facility and then `passed from that cut-off-valve chest to the,

valve-chests of the respective engines; but it is obviously not always necessary to have such long steam-pipe connections as those illustrated, as the cylinders may be closely adjacent.

This improvement is available in any dupleX direct-acting engine, whether the same is simple or compound. When the engines are compound, the cylinders are tandem, with the larger cylinder, in which the steam works expansively, at the rear and in line with the smaller cylinder, into which full pressure is admitted, and the present cut-od is used with the high-pressure cylinders.

I claim as my invention-f l. The combination with the two cylinders and two main steam-chests of a duplex engine,.their cut-off-valve chests, valves, valvegear and cross-heads, of rock-shafts moved by the respective cross-heads and connections from the respective cross-heads .to the valverods of the respective engines, cut-olf valves and primary and secondary cut-0E levers and connections to the respective rock-shafts, the cut-o levers being pivoted together and the primary cut-olf lever swinging on a fixed pivot, and the secondary cut-off levers having a connection to the rod of Vthe cut-off, substantially as set forth.

2. The primary and secondary cut-o levers in combination with the two engine-cylinders, the two main steam-chests, their cutoff-valve chests, valves and valve-gear and the connections from the respective pistonrods to the cut-oft levers and cut-off valves actuated by such primary and secondary cutoff levers, one of the valves being made with an opening in the middle to admit steam to the port and with front and back portions to cover such opening and the other valve being whole and acting at the rear side to cover the port in one direction and at the front side to cover the port in the other direction, substantially as set forth.

3. The combination with the two cylinders and two main steam-chests of a duplex engine, their cut-off-valve chests, valves, valvegear and cross-heads, of rock-shafts moved by the respective cross-heads and connections from the respective cross-heads to the valve rods of the opposite engines, primary and secondary cut-0E levers and connections to the respective rock-shafts, the cut-off levers be-A ing pivoted together and the primary cut-off lever swinging on a fixed pivot and a valverod connected to the secondary lever and two cut-off valves upon the valve-rod and a steamchest for the same with valve seats and ports to the respective engines and nuts or collars upon the valve-rod to communicate motion to the horns of the respective valves, there be= ing greater spaces between the horns than the thickness of the nuts, so that the valves remain stationary during the early portion of the movement of the valve-rod, substantially as set forth.

4. The combination with the two cylinders and two main steam-chests of a duplex engine, their cutoff-valve chests, valves and valve-gear, of a steam-pipe and throttle-valve, a branch and two throttle-valves, the cut-0&- valve chest having a partition and pipes leading from the two throttle-valves to the cut-off steam-chest at opposite sides of the partition, ports and pipes leading to the respective engines, cut-off valves in the chest and one rod for the two cut-o valves, and mechanism for actuating the rod and valves, substantially as set forth.

5. The combination with the two cylinders and two main steam-chests of a duplex engine, their cut-off-valve chests, valves and valve-gear, of two rock-shafts, means for moving the same and the separate engine-valves, cut-off valves and a compound lever composed of a primary and secondary cut-off lever pivoted together and connected to the respective 4rock-shafts, a stationary pivot for the primary cut-off lever and a connection from the secondary cut-off lever to the rod of the cut-off valves, substantially as set forth.

Signed by me this 14th day of January, 1899.

EZRA E. CLARK.

Witnesses:

GEO. T. PINOKNEY, E. E. POHL.

IOO

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