USRE1532E - Improvement in steam-engines - Google Patents

Description

UNITED STATES PATENT OFFICE.

IMPROVEMENT IN STEAM-ENGINES.

Specification forming part of Letters Patent No. 31,226, dated January 29, 1861 Reissue No. 1,532, dated September 1, 1863.

To all whom, it may concern:

Be it known that I, TIsDALE CARPENTER, of the city of Providence, in the county of Providence and State of 4Rhode Island, have invented certain new an d useful Improvements in Steam and other Engines 5 and I do hereby declare that the following is a full, clear, and exact description of the same, reference being had to the accompanying drawings, making a part of this specification, in which- Figure l is a side elevation of the cylinder of a horizontal engine, including that portion of the bed-piece to which it is attached, with the regulator and valvegear in the positions they occupy when the engine is at rest. Fig. 2 is an end elevation of the same in a similar condition. Fig. 3 is a plan view of the same. Fig. 4 is an end view of the cylinder-head with the bonnets removed to expose the valves and their seats to view. Fig. 5 is a central vertical section of the cylinder-head and a portion of thecylinder, showing the valves and passages and the direction of the steam in its ingress and egress to and from the cylinder. Fig. 6 is a plan view on a larger scale than the before-mentioned figures of the lower half of the cam, by which the inductionvalves are operated, and of part of one of the valve-operating levers. Fig. 7 is a vertical section parallel with, but on a scale larger than Fig. 4, of the steam-valve and its surroundings. Fig. 8 is a transverse section corresponding with Fig. 7.

Similar letters of reference indicate corresponding-parts in the several figures.

This invention consists in regulating the velocity of. a steam or other engine by combining the regulator with the induction-valves by means of a valvegear which is positively connected both with the regulator and with said valves in such a manner as to be capable of producing, under the control of the regulator, a variable closing movement of the said valves without detaching or disconnecting them or any portion of the mechanism of the valve-gear, and without the use of any independent power to close the said valves.

It also consists in a novel valve-gear for producing a positive opening and closing movement of the induction-valves and al variable closing movement thereof without detaching or releasing them, composed of a compound cam and rocking levers of variable length combined either with or without a governor; and it further consists in a peculiar arrangement of the exhaust-valves and of their chambers and ports within the cylinder-heads of the engine, whereby the capacity of the wastespace requiring to be filled with steam is reduced to a minimum. 4

To enable others skilled in the art to make and use my invention, I will proceed to describe its construction with reference to the drawings..

A is a portion of the frame or bed to which the working parts of the engine are attached.

B is vthe cylinder, represented as cased to prevent condensation.

C G is the compound cani by which the induction-valves are worked.

D D are the rocking-levers-two in numberto which the induction-valves are attached by the valve-stems t t. rPhese levers are made tubular for the greater portion of their length, and fitted with sliding rods Z Z, carrying on their outer ends friction-rolls r o", placed thereon to avoid friction and wear on the cam O C', the said rods Z Z constituting variable extensions of the said levers D D.

e e are standards carrying the rocking levers and trunnions y y, and also .forming the sup port for the two small-toothed sectors s s, the teethtot which work into similar teeth upon the sliding rods Z Z, and which are connected by rods f f with the regulator in such a manner that as the regulator rises the sliding rods Z Z are moved out from the levers D D, and

the rolls r r are brought nearer to the axis of the cam, and as the regulator falls a contrary eect is produced on the said rods and rolls. The cam C O is fast upon an upright shaft, I, which at the same time constitutes the spindle of the regulator, the lower end of the said shaft being stepped upon the top of the cylinder and a bearing being arranged for its upper end in any way that may be convenient, and the said shaft has fast upon its lower part a spur-gear, G', gearing with a spur-gear, G, of equal size on the upper part of another upright shaft, H, which is intended to be geared in a suitable manner with the main shaft of the engine, that it and the governor, spindle, or cam-shaft I may each make the same number of revolutions that the main shaft does.

' them durable.

The said cam C C is formed of two disks of castiron the corresponding surfaces of which may be chilled or otherwise hardened to make The upper disk, C, has a projection, c 0*, on its under surface, the profile form of which 1s represented in Fig. 2 and the form of its base in Fig. 6 andin dotted outline in Fig. 3. The upper surface of lower disk, C, is made of a form the reverse of the under surface of the upper one-that is to say,

opposite to the projection c c* on the upper one there is a depressiomc 6*, of corresponding form in the lower one-the object being to arrange the corresponding parts so that, however irregular they may be, there will be just room enough for the free passa-ge of the friction-rolls r r between any parts of their surfaces. The said cam rotates in the direction of the arrow shown on it in Figs. 3 and 6,

and as it does so the descending inclinations engine has to overcome the resistance arising from said weight or spring every time that it opens the valve, and, further, with some kinds of valves it insures their return to their seats without any slamming or injury in that respect, and never allows them to stick and leave the ports open when they ought to be closed, which will often happen with engines using weights or springs to close the induction-valves, unless great care is taken in adjusting the stufling-boxes and other parts connected with the valves, as well as the difficulty arising from the variable pressure of steam in the boilers-as, for instance, a weight or spring that will close the valve hnder a pressure of fifty or sixty pounds per inch will 'not be able to do so if any accident should increase the pressure to eighty or ninety pounds, which leads to the objectionable practice of choking the steam in the induction-pipes of engines that work with ysuchmeans of closing the valve.

I will draw a distinction here between this inode of opening and closing the valves and.

any one by whichthe valves working' with a spring or weight may iinally be closed with a positive motion at the end of the stroke, if they should fail to do so at the proper time vfor cutting on". In this mode the valves must come the same force, besides what is due to the weight or spring that is to produce the returning movement.

I will now describe the combined action of the sliding rods Z Z, with their rolls r r, and the cam C Cf, by which the variation in the time of closing the valves and cutting ofie the steam is produced.

In the drawings, the regulator is shown in its lowest position corresponding with a siate of rest, or when the engine is just starting and before it has arrived atits average speed.

It will be seen by reference to the figures that the roll r, belonging to the opening-valvethat is to say, the one to the right hand in the figures is near the outer circumference of the disks C O, its point of contact being upon the line marked l, in Fig. 6. Consequently, the valve will remain open until the disk has roV tated far enough to bring the point marked 1 in line with the roll which corresponds to about three-quarters of the stroke of the engine. This point may be varied at will in construct ing the cam, so as to make the steam follow a greater, or less part of the stroke when the engine is at its lowest speed, and as the speed increases and the regulator rises the latterA will slide the rods Z Z out until the roll r, coming nearer and nearer the center of the disk, will continue closing the valve earlier and earlier as the points 2 3 4L 5 6 7 8 are reached, until the inequalities on the surface of the cam ceases, when it will revolve with outmoving the valves at all, and will consequently entirely cut off the supply of steam. As the rods slide toward the center of the cam, the point of contact of the rolls r 4 is carried farther from the trunnions Y, which are the fulcra of the rocking levers D D at every in crease of the speed, so that the valve not only closes earlier in regard to the stroke, as the engine requires less steam, but when it begins to cut off short, it opens the valve a less distance, which has the effect of making the engine regulate itself with the throttle wide open, no matter how light the load or how high the pressure of steam.

I have described the workin g length of the rocking-levers as being varied by making one part-that is to say, the bar Z-to traverse in the other, but I do not limit myselfto this mode of construction, as they may be made diii'eren tly and produce the same result; or the rollers may be arranged to traverse on the levers.

In order to avoid the waste of steam in the ports and passages of the engine, and to en'- able the piston Y, Fig. 8, to approach as near as possible to the ends of the cylinder, and thereby obvia-te as far as possible the waste of steam in the cylinder itself by filling useless space, as is unavoidable when the parts are in the sides of the cylinder, I make the cylinder-heads M hollow, as shown in the sec tions, Figs. 4, 5,7, and 8, and arrange both the induction-valve QJ and the eduction-valve u in separate chambers, M and M2, formed in their respective heads, both valves being of the sliding kind. The induction-chamber M is supplied with steam through a passage, O, on the top 'of the cylinder with which the steam-pipe connects, and the said chamber communicates with the cylinder by a port, P, which is opened and closed by a valve, v, working perpendicular to the bore of the cylinder. The eduction-chamber M2 is in direct communication with the cylinder, and, being only just large enough for the valve u to work Within it in a direction parallel with the movement of the piston, involves no considerable waste of steam, and the said chamber communicates, by means of a port, u, in the valveseat at its bottom, with a passage, X, which is formed in the bottom of the cylinder to lead to the exhaust-pipe. The stem yn of the said valve works through a stuffing-box in the outside of the cylinder-head, and the said valve opens and closes the port u by a movement parallel with the bore of the cylinder and motion of the piston.

The two eduction-valves are operated by means of a cam, J, on the lower part of the shaft El, before mentioned. This cam works in the yoke k, formed upon or attached to a horizontal sliding rod, L, which works in suitable guides formed upon or attached to the lower part of the cylinder, and the said rod L carries at its ends arms m m, which are attached to thevalve-stems a u.

The object of this arrangement of mechanism for operating the eduction-valves, and one object oi the mode of arranging the said valves themselves is that the said valves are permitted to be opened very quickly at the proper time, to remain at rest with the ports wide open as long as possible, and then to be closed quickly again, and both valves, being attached to the same rod L, of course work in unison.

The advantages obtained by these arrangements over the common mode of applying and operating the valves with an eccentric are, first, that the valves are enabled to be opened and closed quicker, which allows a better legress to the steam 5 second, that' the valve does not have to move so far, only requiring sufficient lap to insure against leakage; third, that it takes less power, because the valve is at rest a part of the time instead of being constantly in motion under steam-pressure, fourth, that the valve is moved at the time when the pressure upon it is least, so that it wears less upon its seat; fifth and last, that as the valve does not have to move so far, there is less space around it which has to be filled and so exhausted at every stroke of the engine. The cam C C and adjustable rocking levers can alsov be used as an adjustable cut-0E on engines vwhich have no regulator by simply using a binding-screw, orits equivalent, to hold the rods Z Z at any place in the levers D D at which the engineer may choose to set them.

The application of these devices are not conned to horizontal engines alone, but with slight modifications, which will suggest themselves to the skillful engineers, may be adapted to upright ones, or to engines having their valves applied in the usual manner, and in all cases they constitute a sensitive and perfectlyregulating automatic cut-olif motion for the inductionvalves of the engine without any liberating valve-gear or the use of any independent power to close the valves after having been openedl by the power of the engine, using the power of the engine to both open and close the valves, and using a positive connection for both the regulator and the valves during the entire stroke of the engine.

What I claim as my invention, and desire to secure byl Letters Patent, is-

1. Regulating the velocity of a steam-engine by connecting a regulator permanently or positively with the induction-valves by means of levers of variable length working between a pair of corresponding cam-disks and employed to close as well as open the valve in a positive manner, substantially as herein specified.

2. The cam C C' and variable rocking le'vers D Z D,Z, working between and controlled by said cams when used in combination with each other and with the induction-valves of a steam-engine, substantially as herein described, either in connection with a regulator to constitute an automatically variable cut-off gear or without a regulator to serve as an adjustable cut-oft'.

3. The arrangement of the eduction-valves and their chambers and ports in the cylinderheads, substantially as and for the purpose herein specified.

TISDALE CARPENTER.

Witnesses:

HENRY MARTIN, ALBERT M. HEwiTT.

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