US413696A - Mechanism for controlling cut-off valves - Google Patents

Description

v(No-lvrod-el.)

J. WHBBLOCK. MEGHANISM :POE GONTROLLING GUT-OPF VALVES.

Patented 001;. 29,1889.

. ."UNITED.4 STATES PATENT OFFICE.

JEROME WHEELOCK, OF WORCESTER, MASSACHUSETTSl MECIdANlSM AFOR CO-NTROLLING CUT-OFF VALVES.

SPECIFICATION forming part of Letters Patent No. 413,696, dated October 29, 1889.

I Application filed March 23, 1889. Serial No. 304,463. (No model.)

` To all whom, it may concern:

Be it known that I, JEROME WHEELOCK, a

citizen of the United States, residing at in Mechanism for Controlling Cut-OIT Valves' in Engines, of which the following, in connection with the accompanying drawings, is a specification sufficiently clear and descriptive to enable those skilled in the art to which my invention belongs to make and use the saine. My invention relates-to automatic cut-off engines in which the cut-off valve is operated by means of the latch block'and link connected to the arm of the exhaust-valve and adapt-ed to be disengaged, from said latchblock by a trip-cam operated by the governor, all of which are well-known and have been fully described in Letters Patent No.144,174, granted to me on October 28,1873; and my invention consists in the improved system of levers and connections by which the trip-cams are operated, as will be fully described, and particularly pointed out in the claims.

Heretofore it has been a serious objection that the link could not be disengaged from the latch-block attached to the arm of the cutoff valve, except at certain individual points of lits forward travel, on account of the stationary condition on part of. t-he trip-cam during the full stroke of the piston, when the engine is running at' comparatively uniform speed-for instance, when the engine is running so slow that thegovernor does not cause the trip-cams to liberate the cut-off valve, even at the farthest point of travel in the valves. Steam is then admitted into the cylinder for almost the full stroke of the piston, and if any load on the engine should be suddenly removed the cut-oif valve cannot be tripped during the return travel of the exhaust-valve crank, and the acceleration in speed would necessarily be so as to disturb the even movement of the fly-wheel, which in some casesis very detrimental to the machines which are driven by the engine-for example, to dynamos for electric lighting, which require a uniform and unvarying speed. This objection I overcome by the improved system of operating the trip-cams forming the subject of this application, and which is fully shown in th drawings, in which- Figure 1 represents a side view of an automatic cut-oif engine generally known as the Wheelock engine and embodying my im-. provenlents. Figs. 2 to li, inclusive, are diagrains showing the positions which the tripcams assume under different conditions in eccentric and governor.

Similar letters refer to similar parts.

In the drawings, A is the cylinder, into the steam-chest a of which steam is admitted by the throttle B and then passes through the cut-off valves C C into the cylinder.

D are the exhaust-valves, allowing the used steam to pass out ofthe cylinder and through the exhaust-pipes b.

As the construction is well known, aswell as the operation of the cut-off valve by the arm of the exhaust-valve, I do not deem it necessary to describe the same fully, as the parts pertaining to the valve-operating mechanism are substantially the same in all cases. E is the engine-bed, supporting at its forward end the crank-shaft F, carrying the eccentric G, which, through the rocker H,im

parts an oscillating motion to the arms c of the main valves.

To the arm c is pivoted the link d, havin gl a bolt d', on which slides a latch-block, which is secured to the arm e of the cut-off valve.

tric-strap Gis attached the link j, the other end ofwhich is secured to the lever I, which 9 5 is pivoted at 7e to the engine-bed E, and the rear end of which is connected through the link Z with the bell-crank lever J. K is the engine-governor, the balls of which cause the rise or fall of therod m., which adjustably roo supports the cross-head n, sliding in ways 0, which are secured to or made integral with the bottom plate o of the oil-reservoir of the governor. The bell-crank lever J is pivoted at p to the cross-head n., and its lower end is in direct connection with' the lever h above mentioned. In Fig. 1 the governor is represented in its lowest position, and the piston may thus obtain full steam from the oommencement of the stroke until the cut-off valve is tripped, which heretofore could only be accomplished during the forward movement of the arm attached to the exhaustvalve. This would allow full steam for the piston for fully three-quarters of the stroke, and if the engine should not require that amount of steam a sudden start on part of the piston would be the result, and the steam could not be shut off on account of the arm of the cut-oft' valve being connected to the v slow-moving arm of the exhaust-valve.

By my improved system, as above described, I positively disengage the arm of the cut-olf valve at any point not exceeding three-fourths of the stroke, allowing the steam to expand and carry the piston to the end of its stroke.

The operation is as follows: rlhe rotation of the shaft F imparts avibrating motion to the lever I, which in turn operates the bell-crank lever J, thereby causing a rocking motion on the part of the trip-cam levers 7L 7L', the amount of which is the same always, but the location of which is regulated or controlled by the governor K, as may readily be seen by referring to Figs. 3 and 4 of the drawings,in which the eccentric is in the same position in both instances, while the cross-head carrying the bellcrank leverJ is in its highest position in Fig.

3 and in its lowest position in Fig. 4. The amount of travel on part of said bell-crank lever J, as indicated by the dotted lines s 3, is the-same; but the location of such movelnent is forward in Fig. 4, so that the tripcams f f', upon the slightest action on part of the governor, may release the cut-olf valve, even during the return travel of the exhaustvalve crank. In Fig. 3 the conditions are rcversed, inasmuch as the travel of the tripcams f f' is such as to prevent any engagement of link andthe arm of the cut-off valve, so that the engine is at all times under full control of the governor, and the cut-olf valve may be tripped at any point of the piston travel upto three-quarters of the stroke. lt will thus be seen that during each revolution of the crank-shaft the trip-cams travel once back and forth, and will consequently disengage the link from the arm of the cut-off valve during either forward or return movement of the exhaust-valve crank and at any point where the cams will encounter said link, the latter condition depending solely upon the position of the governor-balls.

Having fully described and explained my invention and its operation, what I claim new, and desire to secure by Letters Patent,

l. In a valve-gear for controlling the cut-olf valves of steam-engines, one or more tripcams which complete one forward and backward movement during one revolution of the crank-shaft, means for operating the cams, and a governor for controlling the path of -travel of said cams, substantially as and for the purpose set forth.

2. In a valve-gear for controlling the cut-off valves of engines, the combination of one or more trip-cams making a complete forward and backward movement during one revolution of the crank shaft, with a governor whereby the path of such movement is controlled, substantially as and for the purpose set forth.

3. In a valve-gear for controlling the cut-olf valves of engines, the combination of one or more trip-cams with means, substantially as described, for imparting to the trip-cams a complete forward and backward movement during one revolution of the crank-shaft, and a movable fulcrum controlled by the governor for controlling the path of travel of said cams, as and for the purpose set forth.

4. In a valve-gear for controlling the cut-off valves of engines, the combination of one or more trip-cams, an eccentric for imparting to the same a complete forward and backward movement during one revolution of the crankshaft, and a governor whereby the path of such movement is controlled, substantially as and for the purpose specified.

JEROME WHEELOCK. Vitnesses:

CHAs. F. SCHMELZ, IRvING H. FAY.

Images