US684494A - Valve-gear. - Google Patents

Description

N0. 584,494. Patented Oct. [5, 1190!.

. H. G. CAMPBELL VALVE GEAR.

(Application fi led Jan. so, 1901. (No Model.)

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H. 'G. CAMPBELL.

VAL V E G E A B. (Application filed Jan. 80, 1901.)

(No Model.)

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SPECIFICATION forming part of Letters Patent No. 684,494, dated October 15, 1901. Application filed January 30, 1901. Serial No. 45,388. (No model.)

To all whom zit may concern:

Be it known that I, HORACE G. CAMPBELL, a citizen of the United States, and a resident of Portland, in the county of Multnomah and State of Oregon, haveinvented a new and useful Improvement in Valve-Gear, of which the following is a specification.

My invention relates to two mechanisms comprised in steam-engines of the type hereinafter referred to, one of such mechanisms being the means for operating the valves controlling the ports of the cylinder, so as to admit and exhaust steam, and the other being the means for producing a variable cut-off. The mechanism employed by me for accomplishing the result first mentioned in itself provides an efficient means for operating the said valves of said style of engines. To 'accomplish, however, the particular object which I had in view, such mechanism is dependent upon the means employed by me for obtaining the second result-that is, the cutoff. To bring about such second result, I combine with the said valve-operating mechanism certain devices whereby the admission of live steam can be cut off instantly at any desirable point, which point is conveniently variable within practicable limits by the engineer or else automatically controlled by means of a governor. It was also my practical object to use but two valves that should act independently and that the cut-off mechanism should in no wise interfere with the proper action of the valve at the exhaust end of the cylinder, the devices whereby such control of the valves is accomplished to be of efficient,durable, and simple construction and be instantaneous in action when operating to cut off the live steam.

My invention contemplates the use of a cylinder common in engines of marine or horizontal type, such cylinder having ports at each end and individual valves controlling the admission of steam and exhaust, such valves being operated by reciprocating mo tion transmitted from the engine-shaft and such valve-operating devices being adapted to operate as required. Such action of my valve-gear and the certain features of my invention which are the result of my valve-op crating means are herein after fully explained,

reference being had to the accompanying drawings as a part of this invention.

In such drawings, Figure l is an elevation showing a steam-engine of the type referred to with my invention applied thereto. Fig. 2 is an elevation of the cylinder and. one of the valves controlling the ports thereof, such valve being shown in section, and this View shows besides my valve-operating devices and the cut-off mechanism. Fig. 3 is a plan View corresponding with Fig. 2, with the exception that the valve seen in Fig. 2 is in the present figure shown in full plan. Fig. 4 is a partial elevation of the valve-operating devices and cut-off mechanism on an enlarged scale, so as to more clearly illustrate the operation and cooperation of the devices employed. Figs. 5 and G are details of the pawls t t, the functionsof which will be fully understood from the description hereinafter contained. Fig. 7 is a plan view, partly in section, of one of the sliding bars 12 13 and the cooperating parts thereof; and Fig. 8 shows a longitudinal vertical section, the usual D sliding valve so modified as to be adapted to be used in connection with my invention.

The letters and numerals designate the parts referred to in the following description.

Figs. 1, 2, and 4E agree with each other in regard to the position of the engine. Throughout the principal views the cut-off mechanism is shown as set to the shortest admission of steam.- The steam-cylinder a is of the form common to the marine type or horizontal engines and has ports at both ends controlled by individual valves of suitable construction-as, for example, the valve 0. (Shownin Fig. 2.) The valve on the opposite end of the cylinder (not shown) would be a duplicate of the valve 0 and positioned to exhaust steam. The valve-rods d d have at their outer ends sliding bars 6 e, reciprocating in guidesf. The guide-rods are connected with the valve-operating arm j, projecting from the rock-shaft Z, by jointed links g h and g h. The valve-operating arm j is keyed to the rock-shaft Z and has two lateral projecting members i in, each of which members has a shoulder 7" formed in the face of its extremit-y. There is also keyed on the rock-shaft- Z an arm m, Which is reciprocated by cams 0 trolled in the usual manner.

on the engine-shaft operating yokes n, the motion of the latter being communicated through connecting rods and links 19 q in the wellknown manner. The links it h are forked at one extremity, and within such extremities are pivoted the pawls t t, leaving room for the members i and 7c to pass. The cam-operating devices are adapted to be reversible,there being two cams having individual yokes and guides therefor and such devices being operatively connected by a link 30 with the radius-rod g, the latter connecting with the arm m of the rock-shaft, as shown in Fig. 1, and by means of thelever and quadrant 31 the transmission of the cam motion is con- As the engine is positioned in the drawings the valve-gear has just been operated to open the port on the left end of the cylinder, the engine-crank being assumed to have traveled about forty degrees from the left dead-center. As far as described the reciprocating valves controlling the ports of the cylinder are operated in substantially the same manner as is usual in engines of the type referred to. The particular mechanism used by me, however, is adapted to afford a special advantage in this, that by the use of a cam motion in combinanation with articulated valve-stems or connections and a device cooperating with such valve-stems or connections the full or complete motion of the valves either opening or closing the ports is accomplished in one-half the time that it would require even for the quick-acting cam motion to perform the same work. The proof of this assertion is readily obtained from a study of the devices referred to. Above the valveoperating devices is slidably seated in the upper portions of the guides ff a barn, which is operatively connected with the engine cross-head wby means of the pendulum 2, rod 3, and lever or fulcrum-arm 4, so that such sliding bar will have a reduced travel coincident with the travel of the engine cross-head, which travel would be about six inches in an engine of the size represented by Fig. 2, approximately drawn to the scale of one and one-half inches to one foot. Centrally journaled in the sliding bar a is a double bell-crank 5, the central member of which is connected by a rod 6, bell-crank 7, and rod 8 with the lever and quadrant 9, provided for positioning of the double bellcrank 5, and thereby controlling the operation of the cut-off mechanism, as will be seen. The laterally-projecting members of the double bell crank 5 are respectively connected by links 10 11 with the sliding blocks 12 13. An enlarged detail in plan of such sliding blocks is shown in Fig. 7. To receive such sliding blocks 12 13, the two ends of the sliding bars u are provided with slots 14 15, in which the sliding blocks are neatly seated, and the means employed for holding such sliding blocks in place and operatively connecting the same with their cooperating mechanism are disclosed in said Fig. 7. The block here shown is the left-hand one 12. It is provided at its extremities with integral journaled ends 16 17. On the journal end 17 is journaled the tappets 18 between washers 19 20, such parts being held in place by a screw 21 entering the head of the journal 17. Washers 22 23 secured in place of screws 24 25 contribute toward holding said sliding blocks against lateral displacement, and the link 10 being secured on the journaled end 16 between washers 25 26 and such part retained in place by screw 27. The arrangement of the sliding block 13 is like that shown in Fig. 7. The pawls t t, pivoted in the slots of the links h h, are provided with spiral springs 28, which are seated in recesses therefor provided, so control the said pawls that normally the lower ends thereof are thrown against the outer faces of the lateral members t' of the arm j. The relation of the members 7; 70 to the pawls t t is disclosed in Figs. 2 and 4, and as therefrom seen when the arm m has traveled to the position shown the member 76 is thrown under the pawl t in position to engage the same in the notch or shoulder 1", while the opposite membert' has so engaged the pawl t and by lifting against the same has bent the links 9 h to angle shown, thereby shortening the left-hand valve connection with the effect of pulling the valve clear of the port and allowing the steam to enter, as shown'of the valve 0 in Fig. 2. The open valve will remain in that position until the tappet 1S strikes the pawl 15, throwing such pawl out of engagement with the notch or shoulder v in the extremity of the member t' and allowing the links g h to resume a straight or extended position, thereby restoring the left-hand valve-rod to its full length and moving the valve back so as to cover the steam-port. The jar incidental to the release and strengthening of the links 9 h g h is sustained by the dash-pots 29 29. The straightening or return to extended state of the jointed links is accomplished by the ap plication of some means possessing suitable energy. One of the simplest means for accomplishing this work is incorporated in the valve 0.

has been slightly enlarged to provide a small shoulder c and afford slightly-increased steam area. The valve comprises two cupshaped disks, of which the one on the right hand controls the ports, while the opposite disk operates as a piston in the enlarged portion of the valve-chamber. The parts are so proportioned as to give to the steam acting on the piston-d isk of the valve an energy of about one hundred and fifty pounds, pulling against the armj and operating to keep the jointed portionsofthe valve connections normally in an extended state. The devices controlling the valve for the opposite end of the cylinder are a duplicate of the parts described as operating the valve 0, and of course when the valve 0 is in (Seen in Fig. 2.) It will be ob 1 served that the left end of the valve-casing a position as shown in Fig. 2 the valve in the opposite end of the cylinder would be at exhaust position. In order that my invention will operate as described, it is essential that the parts of the valve-gear be relatively proportioned. Such relative proportions are substantially given in the drawings, the same representing as follows: It is assumed that the cam 0 gives to the radius-rod q a motion or travel of three and three-fourths inches and a corresponding travel to the lower rockshaft arm m, which is assumed to have a length of eight inches from center to center, and that in correspondence with such measurement the upper rock-shaft arm j has a length of three and one-quarter inches from center to center, so that the length of the path of travel of this arm would be one and one-half inches. The links 9 h and g h are respectively assumed to be eight inches from center to center, and when lifted or bent by the laterally projecting members 2' 7a the joints between such links would rise three and one-quarter inches out of a straight line, with the effect of shortening the valve connection and operating such valve as described. The movement of the valve so obtained would equal one and a half inches, which, together with the travel of the valve due to the motion of the arm j being also equal toone and one-half inches,would make the total or complete travel of the valves three inches, it being further assumed with the given dimension that the ports of the cylinders are one and one-sixteenth inches in width and that the faces of the valves controlling such ports have a length of one and thirteen-sixteenths inches,including a steamlap of one-half an inch and an exhaust-lap of one-quarter of an inch for each valve. In cooperating with the described valve-gear the tappets 18 18, carried by the" sliding bar a, when brought in contact with the pawls t t trip the latter and by so doing release the jointed links of the valve-stem, allowing the energy of the steam acting in the enlarged portion of the valve-chamber to pull the valve against the restraint of its connections by the rock-shaft straightening and extending its said connection, and in so doing the valve travels, as has been stated, one and one-half inches, or sufficient to cover the open port, and brings about the cut-off. As shown in the drawings, the point of cut-0E is adjusted to its shortest practicable point, which is about one-eighth of a stroke of the engine, and assumes the rock-shaft arm m to be in the position shown in the drawings and that in correspondence therewith the enginecrank to have reached a point forty degrees below the left-hand dead-center. My reason for adopting a cam motion for operating the rock-shaft Z instead of eccentrics is to cause such rock-shaft to have an intermittent motion and remain in a state of rest during the travel of the engine-crank over an arc of one hundred degrees between dead-centers--that is to say, while the engine-crank is traveling between the point forty degrees past one dead-center and to the point forty degrees in advance of the opposite dead-center. This is obviously an essential provision, inasmuch as the positioning of the valves to admit steam is accomplished by the action of the members t' contractingthe jointed links of the valve connections, and it is desirable that the steam-admitting valve remain wide open until the very instant the steam is to be cut off. On the other hand, while such jointed links of the valve connections are held in contracted position they are within the path of travel of the mechanism carried by the reciprocating bar it for releasing such contracted valve connection and allow the same to be extended again to produce the cut-01f, and it will be observed that the described action of the valve controlling the port at the receiving end of the cylinder is independent of the valve controlling the opposite port, which will remain wide open to exhaust and all excessive compression of steam at the exhaust end of the cylinder be avoided.

From the above-described mechanism of the cut-0E devices it is apparent that they are adapted to operate instantaneously.

My invention also involves a very desirable feature in this, that the length of travel of the valves and their incidental wear are unadected by any adjustment of the cut-off devices. At whatever point the cut-off may be accomplished the valves constantly retain their full stroke or travel. Consequently the objectionable uneven wearing away of the valve-seat is prevented.

Fig. 8 shows.the application of the D sliding valve in connection with my invention. I have represented in this figure what is commonly known as a balanced slide -valve. The casing thereof is, however, so modified as to provide the cylindrical chamber 32, having a length corresponding to the travel of the valve. The valve is provided with a projecting stem 33, carrying at its end a piston which operates in said chamber 32, one side of such piston being exposed to the steam admitted into the main valve-chamber. The area of the chamber 32 is such as to give the steam an energy of about one hundred and fifty pounds for pulling back the valve against the restraint of its connections and operating as has been stated with respect to the construction of the valve 0.

While my valve-gear has been shown and described as applied to a horizontal type of engine, such, of course, is not its limitation. It may also be applied to vertical engines, and in cases where my invention is to be applied to an engine the cylinder of which is of insuflicient length to admit of the installation of the valve mechanism between the cylinder-heads, as shown in the drawings, it would be a simple matter to so modify the said valve mechanism as to be installed at the heads of the cylinder instead of between the same and provide each valve with individual valve-gear and cut-off devices coincidentally operated from twin rock-shafts.

Having fully described my invention, now What I claim, and desire to secure by Letters Patent, is-

1. In a valve-gear, the combination of the cylinder and the ports thereof; individual valves independently controlling such ports; a rocking device operatively connected with the engine-shaft; connections from such rocking device to said valves, such connections comprising in part jointed links or portions adapted to be thrown into angular or contracted position, and extended again, to accelerate the travel of the valves; means acting to normally keep extended such jointed portions of the valve connections; and means cooperating with said rocking device, alternately engaging and contracting said jointed valve connections, to thereby accelerate the positioning of the valve at the receiving end of the cylinder to admit steam, substantially as described.

2. In a valve-gear, the combination of the cylinder and the ports thereof; individual valves independently controlling such ports; a rocking device operatively connected with the engine-shaft; connections from such rocking device to said valves, such connections comprising in part jointed links, or portions adapted to be thrown-into angular or contracted position, and extended again, to accelerate the travel of the valves; means acting to normally keep extended such jointed valve connections; means cooperating with said rocking device, alternately engaging and contracting said jointed valve connections, and thereby accelerating the positioning of the valve at the receiving end of the cylinder to admit steam; devices traveling with the engine and adapted to release again the contracted valve connections, such releasing devices being adjustable to act at convenient point of the engine-stroke; and means operating to receive the jar or shock incident to the sudden release of said valve connections, substantially as described.

3. In a valve-gear, the combination of the cylinder and the ports thereof; individual valves independently controlling such ports; a rock-shaft operatively connected With the engine-shaft; an arm fast to such rock-shaft; connections from the valvesv to such arm, such connections comprising in part jointed links or portions adapted to be thrown into angular, or contracted position, and extended again, to accelerate thetravel of the valves; means acting to normally keep extended such jointed portions of the valve connections; a pair of arms laterally projecting from the rock-shaft, and adapted to alternately engage and contract said jointed valve connections to thereby accelerate the positioning of the valve at the receiving end of the cylinder to admit. steam, substantially as described.

4. In a valve-gear, the combination of the cylinder and the ports thereof; individual valves independently controlling such ports; a rock-shaft operatively connected with the engine-shaft; an arm fast to such rock-shaft; connections from the valves to such arm, such connections comprising in part jointed links or portions adapted to be thrown into angular, or contracted position, and extended again, to accelerate the travel of the valves; means acting to normally keep extended such jointed valve connections; a pair of arms laterally projecting from the rock-shaft, and adapted to alternately engage and contract said jointed valve connections, to thereby accelerate the positioning of the valve at the receiving end of the cylinder to admit steam; a reciprocating sliding bar operatively connected with the engine, and provided with adjustable devices adapted to release again, at any practicable point of the engine-stroke, the valve connections that have been contracted to move the valve to admit steam as specified; and dash-pots adapted to receive the jar or shock incident to the sudden release of such valve connections, substantially as described. v

5. In a valve-gear, the combination of the cylinder and the ports thereof; individual valves independently controlling such ports; a rock-shaft operatively connected by a cam motion with the engine-shaft, the arm, j, fast on the rock-shaft, and having laterally-projecting members, 1', 7c; the valve-stems; the guides therefor, and connections between such valve-stems and the arm, j, such connections comprising jointed links or portions adapted to be thrown into angular or contracted position, and extended again, to accelerate the travel of the valves; means acting to normally keep extended such jointed links; devices carried by said jointed links for adapting the same to be temporarily engaged and operated by the members, c, 7c, of the arm, j, respectively to accelerate the positioning of the valve at the receiving end of the cylinder to admit steam, the reciprocating bar and guides therefor; adjustable devices carried by said reciprocating sliding bar releasing again the jointed valve connections from the members, i, 70, respectively, after having been operated thereby; means for adjusting said devices to act at any practicable point in the engine-stroke; and the dash-pots adapted to receive the jar or shock incident to the sudden release of such valve connections, substantially as described.

6. In a valve-gear, the combination of the cylinder and the ports thereof; individual valves independently controlling such ports, the rock-shaft operatively connected with the engine-shaft by a cam motion; the arm, j, fast on. the rock-shaft, and having laterally-projecting members, t, 70; the valve-stems and guides therefor; connections between such valvestems, and the arm, j, such connections comprising jointed links or portions adapted to be thrown into angular, or contracted po sition, and extended again, to accelerate the travel of the valves, said valves being adapted to exert a lengthwise pull on their connections, so as to normally keep the jointed portions thereof extended; the spring-controlled pawls, t, 25, carried by the jointed links of the valve connections, and adapted to be engaged by the members, *6, k, respectively to accelerate the positioning of the valve at the receiving end of the cylinder to admit steam; the reciprocating bar, It, and the guides therefor; the double bell-crank, 5 5 the connections, 10, 11; blocks, 12, 13, provided with device adapted to trip the paWls when engaged by the members, t, it, so as to release again the valve connection that has been contracted, and al- HORACE G. CAMPBELL.

Witnesses:

T. J. GEIsLER, E. M. HOWATSON.

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