US367330A - barnaby - Google Patents

Description

N o ModeLf 2 Sheets-Sheet 1 O. W. BARNABY.

STEAM ENGINE GOVERNOR. No. 367,380. Patented July 26, 1887..

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2 Sheets-Sheet 2 G. W. BARNABY.

STEAM ENGINE GOVERNOR.

(-No Model.)

Patented July 26, 1887.

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INVEN? WITNESSES M ATTORNEY.

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U ITE STATES, PATENT 'OFFICE.

oHAnLEs w. BARNABY, or SALEM, OHIO, ASSIGNOR or ONE-HALF TO THE BUCKEYE ENGINE COMPANY, or SAME PLACE.

STEAM-ENGINE GOVERNOR.

SPECIFICATION forining part of Letters Patent No. 367,330, dated July 26, 1887. Application filed April 2, 188?. Serial No. 231.411. (Yo model.)

To all whom it may concern:

Be it known that I, CHARLES W. 'BARNABY, of Salem, in the county of Oolumbiana and State of Ohio, have invented certain new and useful Improvements in Steam-Engine Governors,of which improvements the followingis a specification.

My invention relates to centrifugal governors or regulators for steam-engines and other motors, and, while applicable generally to such mechanisms, is more particularly designed for and adapted to use in that class of governors which are mounted on the main shaft of the motor.

The object of my invention is to enable an increase in the scnsitiveness, eficiency, and capacity, and a reduction in the cost of construction of centrifugal governors, to be attained by the provision ofsprings,the construction and combination of which, with other elementsof the governor, shall be such as to maintain a uniform factor of safety against breaking strain throughout all parts of the springs.

To this end my invention consists in certain novel devices and combinations hereinafter fully set forth.

In the accompanying drawings, Figure 1 is a rear View, in elevation, of a governor embodying my invention; Fig. 2, a vertical section through the same at the line :0 of Fig. 1; Fig. 3, a front view, in elevation, of the same; Figs. 4, 5, and 6, views in elevation, illustrating, respectively, different forms of springs; Fig.7, a front view, in elevation, of a governor, illustrating a modification of my invention; and Fig. 8,a vertical section throughthe same at the line yyof Fig. 7.

My invention is herein exemplified as applied in a shaft governor of the class which antomatically vary and control the point of outed in steam-engines,in accordance with variations of pressure or resistance, or both, by antomatically moving across or around theshaft an eccentric, cam, or crank connected by suitable intermediate mechanism-with a valve or valves controlling the supply of steam to the cylinder. My improvements are, however, likewise desirably applicable to governors mounted upon shafts independent of the main or driving shaft of the engine, and receiving their motion therefrom by gearing, belts, or other analogous means. Governors of such character, as ordinary, throttlinggovernors, the Corliss, Porter, and others, are generally 5 5 placed upon the steam-pipe, steam-chest, or frame of the engine, and control the supply of steam to the cylinder, either by throttling or partially closingthe passage for steam thereto or by adjusting the point of cut-off by their action upon valve mechanism of various descriptions. The improvements are likewise applicable, without substantial variation of structure or principle of operation, to governors for electric,hydraulic, gas, and other motors.

In the practice of my invention, referring particularly to Figs. 1, 2, and 3, the members by which the desired adjustment of the eccentric 13 is effected aremounted upon and supyo ported by a wheel, disk, or case, 1, which is bored out centrally to fit and be fixed upon the main or crank shaft ofthe engine or upon a countershaft rotated thereby. Two weightarms or weighted levers, 2 2, are journaled at diametrically -opposite points upon weightpivots 3 to theeasel, and are coupled one to the other by alink, 4, fitting at its ends around pins 5 on the arms. The linlut is coupled'by a pin, 6, man arm, 7, fiXed upon ashort shaft, 8, which isjournaledfnthe case in line with the weight-pivots 3, the distances between the centers of the pins 5, 6, and 5 upon the link being equal, respectively, to the distances between the'centers of the pin 3, shaft 8, and pin 3 of the three arms connected by the link measured in the same direction. The shaft 8, which carries the arm 7, on one of its ends, is fitted to move freely about its axis in a hearing in the case 1, and has secured upon its 0 opposite end a crank, 9, upon the pin 10 of which is fitted a rectangular block, 11, which works in a slot, 12, in an arm or projection on the eccentric 13, which actuates the valve or valves controlling the admission of steam to 5 the cylinder. The eccentric 13 is fixed upon a shaft, 14, which is journaled in a bearing in the governor frame 1, parallel to the axis thereof.

It will be obvious, without illustration, to I00 those skilled in the art that the connection of four or more arms or levers of a governor mechanism by a single continuous link coupled in line to each of the same may be effected without departure from the operative principle of my. invention, as exemplified in the instances above described.

The centrifugal action exerted in the open ation of the governor by the weight-arms 2, which tends to move the eccentric in the direction proper to effect a shorter cut-off, is opposed by ecntripetally-acting springs 17 ,17 17", each of which connected at one end to a clip, 22, on one of the weight-arms, and at the other to a lug or fixed support on the governor-case. Each of the springs shown, as well as springs of other forms, may be applied in the governors shown, and the specific springs herein described and shown are likewise applicable in governors of other types.

In Figs. 1, 2, and 3 the weight-arms 2 are shown in their extreme outer positions, being the positions occupied by them when the motor upon which thegovernor is applied is running up to speed without load. Under the heaviest practicable load of the motor, or when running under speed or at rest, the arms would be at their extreme inner positions, the centers of the weights or balls 18 being then at the points 19, and the center of the eccentric 13 being correspondingly shifted from the point 20 to the point 21.

The springs are obviously subjected to their maximum strain when the governor is in operation and the weight-arms are in the positions in which they are shown in Figs. 1, 2, and 3. Thestrain on the springs is induced by two separate forces, which may be termed, respectively, the external and the internal force. The external force is due to the centrifugal force and inertia of the weights or weighted free ends of the arms 2, modified to a greater or less extent by the centrifugal force and inertia of the arms, links, eccentric, and, in fact, all the moving parts of the governorr" This force is concentrated at the 7 spring-clip 22 into a direct pull on the spring.

The internal force is due to the centrifugal forccof the spring alone. The former force affects the springs equally throughout their entire length, while the latter varies, with extension-springs, from zero at one or both ends to a maximum at the other end or at an intermediate point, according to the location of the spring in relation to the center of rotation.

To illustrate more fully the forces above stated, Fig. 4 represents, on an enlarged scale, a spring, 17, placed substantially radially in a governor, as in Fig. 1, and subjected to maximum stress and extension, the center of rotation of the governor being indicated by the point 23 and the point of application of external force to the spring proper bya. It will be obvious that the pointa is subjected only to the external force together with the centrifucoil is subjected, in addition to the external force, to the combined centrifugal force of all theprcccding coils, thclast orinncrmost point, :0, being compelled to sustain the centrifugal force due to the whole weight of the spring.

It; will thus be seen that when a radial spring is caused to revolve about a center, as in the instance shown, the part of the spring nearest the center will be subjected to greater stress than the part farthest therefrom, the extentof the additional force varying, with a given spring, as the square ofthe number of revolutions which it makes in a unit of time. In order, therefore, that a spring may possess a uniform factor of safety throughout, it should be so constructed thatits strength at each point should be as nearly as practicable in proportion to the stress put upon it at such point.

Inasmuch as the safe load which can be sustained upon a spring varies inversely as the diameter of the coil, or as the cube of the diameter of the rod, the diameter of the coil remaining equal, the strength required to sus tain the internal force may be secured either by diminishing the diameter of the coils as the stress increases or by enlarging the diameter of the rod of which the spring is formed, or both, as may be preferred.

Figs. 1 to 4 illustrate springs formed of a rod of uniform diameter and with coils of such relative diameters as will equalize, at the speed under which the spring is designed to operate, thestrain with the resistance on all of its parts, respectively. In this casealine drawn through the centers of the rod at each coil would be of curved form, as indicated by the line 25 26 27, Fig. 4; but this form may, if desired, be approximated with sufficient accuracy for practical purposes by forming the spring of regular or uniform taper, following the line 28 29 of Fig. 4, as shown in Fig. 5.

In the spring, Fig. 6, the equalization of strain and resistance is attained by forming the spring of a rod of continuously-increasing diameter from the circumferential to the central extremity of the spring, the coils being of uniform diameterthroughout, the tapered rod producing the same result as the tapered coil of Fig. 4.

The proper form of the spring may be determined by taking the maximum external force required to be sustained by the spring at the point a, and calculating the proper diameter of rod and coil to carry the load with the desired factor of safety. The weight of the outer coil, 0. b, is'then figured, and its distance from the center of revolution, 23, and the number of revolutions being known, the centrifugal force of the coil a I) may be calculated and added to the external force acting IIS on the point a. The diameter of the next coil, b 0, may then be calculated to ascertain the reduction necessary to enable it to properly carry this load. In like manner the centrifugal force of the second coil, 1) c, is calculated and added to the sum of the external force and the centrifugal force of the first coil, and

' same way, the diameter of the 'coils remaining constant and a diameter of rod being figured which will safely sustain the load after each increase from coil to coil. I have found preferable, in practice, a spring formed of a rod of uniform diameter and having its coils progressively reduced in diameter, as first described, by reason of its greater facility economy of construction.

As before explained, the taperof the spring will vary according to its location and the velocity with which it revolves, and I have ascertained in practice that the internal and external forces acting at the inner end, 00, of the spring are, in average cases, substantially equal-that is to say, the centrifugal force of the spring which itsnstains at the point 00 is substantially equal to the external force apand , plied to the spring atthe point 24. The point a; being hence subjected-to twice the strain sustained at the point a, the diameter of the coil at the point 00 should be one-half the diameter at the point a.

Referring to Figs'l and 2, it will be seen that where the shaft upon which the governorcase is secured does not extend past the face of the hub adjacent to the springs the inner ends thereof maybe extended inwardly to the center of rotation, and there united so as to form one continuous spring extending from one weight-arm to the'other. .A spring thus constructed-that is, with coils of minimum diameter at its center and tapering to maximum diameter at its ends-would be of proper form for an extension-spring crossing the cen ter of revolution, whether both ends were attached to movable arms or one to a movable arm and the other to a fixed support on the governorcase. The samerule is measurably applicable to springs which extend across the axis of'rotation exterior thereto, as in Fig. 7. It is obvious that in such case the centrifugal force of the spring itself is not exerted in the direction of its axis, but at right angles thereto, opposite the center of rotation and inclining toward the axis of the spring as each of its ends is approached. The centrifugal force acting at different angles to the axis of the spring may be resolved at any point of the length of the spring into two component forces, one acting in the direction of the axis-and the other at right angles-thereto. It will then be found that the axial force is the sameas though the spring passed through the axis of rotation. The spring is therefore subjected to the same force in this direction as a radial spring, with an additional force acting upon it at right angles. The effect of this latter force may be better understood by comparing the flexible spring with a cable suspended between the points, as in a suspensionbridge, with weights attached corresponding with that portion of the centrifugal force which acts at right angles to the spring. In this case, according to wellknown mechanical laws, the cable would be subjected to uniform tension throughout its length, as would be the case with the spring. As the external force applied to the spring also affects it uniformly throughout its length, the tension on the spring due to the force acting at right angles to its axis may be consid ered as so much external force. When running at moderate speeds, the centrifugal force acting on the springs would not materially affect them, and the springs would be subjected to so little internal force as to approximate closely in their theoretical form to a cylinder, in which case only a small percentage of the full capacity of the spring is consumed in internal work, leaving almost the entire capacity of the spring available fol-actual external work. It is obvious that the actual external load which can be placed upon the spring only has any effect in the operation of the governor, the internal force being lost. XVhen, however, the governor is opera ted under even the moderate high speed .of present approved practice, the loss from internal strains becomes a matter of substantial importance, and at the highest tension the coils nearest the center of rotation in the ease of extension-springs, and farthest from it in the case of compression-springs, would be strained to such an extent by the centrifugal. effect of the remainder of the spring as to leave little or no force available for actual or external duty; but while the inner coil would be strained almost or fully up to the breaking-point the outer coil might have little or,

' in fact, no strain upon it. It will thus appear that while considerable energy may remain in the outer coils it isimpracticable to utilize it, for if external work be added after the inner coil is subjected to its maximum safe strain this portion of the spring will be unduly strained. By placing the springs at one side of the center a fair length of spring may be provided with much less centrifugal effect longitudinally; but the transverse strain is exerted to so great an extent as to render the spring nearly as inefficient as a radial spring as regards external work.

Under my invention I am enabled to utilize 5 each and every portion of the spring up to its full capacity for external work, thus obtaining the maximum duty with a minimum of material, and I am further-enabled to construct a governor which will be fully effective in operation at speeds much above those at which proper regulation has heretofore been found practicable.

Vhere the springs are used in compression instead of in extension, as heretofore considered, the action will be substantially similar to that hereinbefore described; but the spring is in such case to be tapered in the opposite directionthat is, having its larger diameter nean est the center of rotation.

Fig. 7 illustrates an application of a compression-spring, 17", in which it will be seen that the inner end is only subjected to the ex ternal load, while the outer end sustains the load due to the centrifugal force of the spring, in addition to the thrust due to the external load applied at the inner end. The spring should therefore be constructed with asmaller diameter of coil or a larger diameter of rod at its outer than its inner end, to sustain the additional load orinternal force acting upon the former.

The connection of thethree lever-arms 2 7 2 by-a single continuous link enables one link and one pin to be dispensed with as compared with prior constructions. The practice heretofore has been where two weight-arms were employed to actuate a third arm or member, as the crank-arm 7, Fig. 1, either to connect the two weight-arms directly together by a link running from one to the other and extending a second link from one of the arms to the third mcn1ber,or to connect the weight-arms independently by two separate links to the third member, thereby indirectly coupling the weight-arms together through the third member. In the latter case the ordinary construction would be to attach a double arm to the shaft 8, Figs. 1, 2, and 3, with a second pin diametrically opposite to the pin -6. A link 0 would then be connected with each of these pins and with the weight-arms 2, involving the necessity of two links and four pins as against one link and three pins in the application of my improvement. I thus simplify and economize the construction of the governor, as well as wear, maintenance, and friction in operation. The increased effectiveness of the springs, by the construction of which a smaller quantity of material is made available for the proper performance of the centripetal function than in springs as heretofore constructed,

presents a further element of advantage and economy.

I claim as my invention and desire to secure by Letters Patent- 1. The combination, in a centrifugal governor, of a weight-arm and a centripetallyacting spring coupled to the weight-arm and constructed to present a continuously-varying resistance from one point to another of its length, substantially as and for the purpose set forth.

2. The combination, in a centrifugal governor, of a weight-arm and a eentripetallyacting spring coupled to the weight'arm and having coils of diameters varying continuously throughout its length, substantially as set forth.

3. The combination, in a centrifugal governor, of a supporting disk or case, a weightarm pivoted thereto, a centripetal!y-acting spring coupled to the weight-arm and to the case, and constructed substantially as described, to present a continuously-varyiug resistance throughout its length, and a movable eccentric or cam coupled to the weight-arm, substantially as set forth.

4. The combination, in a centrifugal gov ernor, of a supporting disk or case, a pair of weight-arms pivoted thereto 011 opposite sides of its center, a centripetally-acting spring coupled at its ends to the weightarms and constructed to present a cont-innously-varying resistance from its center to each of its ends, and a movable eccentric or cam coupled to the weightarms, substantially as set forth.

5. The combination, in a centrifugal governor, of a supporting disk or case, a pair of weight-arms coupled thereto, a centripetallyacting spring or springs coupled to the case and to the weight-arms, an eccentric fitted to move relatively to the case, one or more arms connected to the eccentric and having bear ings in line with the weight-arm pivots, and a continuous link coupled to the weight-arm pivots and the eccentric arm or arms,'substantially as set forth.

6. The combination, in a centrifugal gov ernor, of a supporting disk or case, a pair of weight-arms pivoted thereto, a centripetallyacting spring or springs coupled to the case and to the weight-arms, an eccentric fitted to move relatively to the case, a shaft journaled in a bearing in the case and coupled to an arm on the eccentric, and a continuous link coupled to an arm on said shaft and to the weightarms, substantially as set forth.

CHARLES XV. BARNABY.

\Vitnesses:

ROBERT HALL, W. \V. HOLE.

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