US1180583A - Governing mechanism for water-driven turbines. - Google Patents

Description

A. GAGG.

GOVERNING MECHANISM FOR WATER DRIVEN TURBINES.

APPLICATION FILED JULY 14, 1915.

I Patehted Apr. 25,1916.

3 SHEETS-SHEET I.

A. GAGG.

GOVERNING MECHANISM FOR WATER DRIVEN TURBINES.

APPLICATION FILED JULY 14, 1915.

Patented Apr. 25, 1916.

3 SHEETS-SHEET 2.

A. GAGG. GOVERNING MECHANISM FOR WATER DRIVEN TURB INES.

APPLICATION FILED JULY 14. 1915.

Patented Apr. 25,1916.

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m nnnnn W an'rou ease, or airmen, sw rznnLaun, assre non 'ro THE FIRM AKTIENGESELL- SCHAFT DER MASCHINENFABRIKEN ESCHER, WYSS & 00., or ZURICH, swrrzna- LAND.

Specification of Letters Patent.

GOVERNING MECHANISM FOR WAT1ER-DRIVEN TURBINES.

Patented Apr. 25, 19116..

Application filed July A, 1915. Serial No. 39,847.

To all whom it may concern:

Be it known that I, ANTON GAGG, a citizen of the Republic of Switzerland, residing. at Zurich, Switzerland, have invented new and useful Improvements in or Relating to Governing Mechanism for ater-Driven Turbines and other Prime Movers; and I do hereby declarevthe following to be a full, clear, and exact description of the invention, such as will enableothers skilled in the art to which it appertains to make and use the same,reference being had to the accompanying drawings, and to letters or figures of reference marked thereon, which form a part of this specification.

This invention relates to means for securing freedom from oscillation in governing mechanism for prime movers and more particularly water-driven turbines by the use of hydraulic, indirectly-acting speed governors.

The essential features of the present invention consist in providing means whereby the travel of the controlling organ of the auxiliary motor participates only within relatively narrow limits of the movements of the centrifugal governor. A yielding member, for instance a dash-pot, is so connected with a controlling linkage that the centrifugal governor is capable of continuing its travel after the controlling organ has reached its end positions. The centrifugal governor, immediately upon a reversing of its movement, imparts to the controlling organ the same degree of movement.

A constructional embodiment of the invention consists in providing, in connection with the dash pot, springs that act to return the dash pot cylinder after each displace-- ment to its mid position, for the purpose of restoring after each governing the position of the controlling organ in dependence upon the centrifugal governor, said position being required for keeping a certain speed or number of revolutions of the prime mover.

The apparatus is adapted for use both in connection with constant speed governing systems and systems of the kind wherein a certain given new speed or number of revolutions corresponds to each new load.

The accompanying drawings illustrate constructional examples of mechanism embodying the invention adapted for use in connection with water-driven turbines, and also illustrate diagrammatically the governing o erations or effects obtainable by means 0 the governing mechanism according to the present invention.

F gure 1 is a front elevation, partly in sectlon of one form of construction. Fig. 2 1s a vertical section of the casing of the controlllng valve, showing the governing piston arranged within the casing in its lowest position. Fig. 3 is a vertical section of the casing of the dash-pot, showing the piston of the latterdisplaced relatively to the middle of the dash pot casing. Fig. 4 is a vertical sectioncorresponding to Fig. 2 showing the governlng piston in its uppermost position. Fig. 5 illustrates diagrammatically the governing operations or effects obtainable by means of the mechanism shown in Figs. 1 to 4. Fig. 6 is a vertical section of a second constructional form. Fig. 7 is a vertical central section of the dash potshown' in Fig. 6, illustrating the parts in another position. Fig. 8 illustrates diagrammatically the governing operations or effects obtain able by means of the mechanism shown in Figs. 6 and 7. Fig. 9 is a vertical section of a third constructional form. Fig. 10 illustrates diagrammatically, the governing operations or effects obtainable with positive and negative returning arrangements respectively. Fig. 11 is a vertical section of a dash-pot, illustrating springs arranged externally to the dash-pot cylinder. Fig. 12 is a vertical section of a friction coupling that may be used instead of a dash pot. Fig. 13 is a horizontal section at line A-B of Fig. 12. V

In the example shown in Fig. 1 the casing 2 of the controlling valve for the auxiliary motor which can work with a fluid under pression for instance water or oil under pressure has stops, by which the travel of the governing piston 3 movable within the casing 2 is kept within narrow. limits. In the present case the auxiliary motor comprises the casing 4 and differential pistons 5. 5 and is connected to a pipe system 30. that receives water under pressure from the main supply pipe .81 leading to the water turbine 32, that drives also the centrifugal governor 1. A. dash pot is intercalated in the linkage system between the governing piston 3 and the centrifugal governor 1. The dash pot consists essentially of a cylinder 6 and a piston 7. The spaces in the dash pot cylinder 6 above and below such piston are tilled with oil and the dash piston is formed with a small perforation 11 that places the said spaces in communication with each other. l pon the centrifugal governor 1 being caused to rotate at'a higher speed owing to the load on the prime mover being l ghtened its sleeve raises the left hand end of the. lever 8 and turns such lever in a clockwise direction about its stationary fulcrum 9. The right hand end of the lever 8, acting through the link 10 thereupon pressesthe dash pot piston 7 downward. The perforation 11 is however so small in diameter; that in the short period of the movement, which is momentarily in a downward direction itis not possible for a suflicient quantity of oil to flow from the lower to the upper side of the piston 7 to admit of the'piston moving freely relatively to the cylinder 6. A momentary driving connection, although ofa slightly elastic or yielding nature. is accordingly set up be tween the piston 7 and'the cylinder 6, and consequently the piston 3 of the controlling valve to which the cylinder is rigidly connected, willalso be pressed downward into the position shown in Fig. 2. In this position of the controlling piston 3 the way is clear to the outlet pipe 12 for the Water under pressure on the right hand side of the large piston 5 of the auxiliary motor, so that the pressure on the right hand side of the piston 5 falls. The continuously prevailing high pressure of the water between the large piston 5 and the small piston 5 is consequently able to push the two pistons to the right and thus by means of the link 14 and lever 15 to turnthe main governor shaft. 16 in a counter-clockwise direction, this resulting in a closing movement of the main admission valve 33 or equivalent devices of the prime mover. A slight upward movement of the sleeve of the centrifugal governor 1 will suffice to push the piston 3 of the controlling valve far enough downward to cause such piston to travel the entire length of its stroke, as such travel is quite small relatively to the whole travel of the governor sleeve. It need for instance only amount to one millimeter out of the mid-position. The right hand end of the lever 8 is however capable of traveling altogetherthrough a distance that is much greater than the aforesaid travel of the piston 3. Even when the controlling piston 3 is seated at the bottom in the casing 2, see Fig. 2, the speed governor isstill capable of further movement in theoriginal direction, as the dash pot piston I b 7 then becomes displaced downward to a corresponding extent within the dash pot cylinder 6 and displaces the oil below it up through the perforation 11, the said piston moving into the position shown in Fig. 3. When however the speed of the centrifugal governor decreases after the main inlet valves or equivalent devices have been moved into the position corresponding to the new load, so; that the governor sleeve begins to descend, the dash pot piston 7 which at this time is being drawn upward by the right hand end of the lever 8 again becomes momentarily coupled, by means of the oil over such piston, to the dash pot cylinder 6, the piston at this time being in the position shown in Fig. 3, it having been moved downward out of its mid position. The piston 7 'as it is being drawn upward draws upward along with it the dash pot cylinder 6 and consequently the piston 3 of the controlling valve, until the latter piston reaches its mid position, a fresh period of repose being thereby set up. This governing operation is graphically represented in Fig. 5 wherein the time corresponding to any given governing operationis indicated as abscissae measured from left to right, the ordinates representing on the one hand the speed or number of revolutions n of the prime mover (the thin line) and on the other hand the amount of opening 0 of the main inletvalves or the like (the heavy line). At the point of time t suppose the preexisting state or repose to be interrupted by a lightening of the load on the waterdriven turbine. As a result the turbine speed will be accelerated and the centrifugal governor l raises its sleeves and acts as hereinbeforedescribed, through the dash pot 6-7, distributing valve 2-3, and auxiliary motor 455, to turn the governing shaft 16 in a counter clockwise direction and thus close the main distributing valves or the like.

Referring to the diagram, Fig. 5, the speed of the prime mover is represented as having had the value n during the first state or period of repose, that is to say, up to the time t and the main inlet valves or the like were open by an amount 0 Up to the time F, the speed of the prime mover rises to the amount n while at the same time the centrifugal governor acts in accordance with the governing operation hereinbefore described to bring about a reduction of the sectional area of opening of the admissionvalves or the like down to the amount 0 At the same 23 the amount of energy transmitted by the water on the turbine shaft is exactly equal to the duty required of the turbine at the increased speed a". The auxiliary motor 4, 5, 5 however moves further in a direction to close the main admission valves thereby causing the speed of rotation to fall from the value 71?. This in turn causes the governor sleeve to descend and thus raise the dash pot piston 7. As already stated the dash pot piston 7 draws the dash pot cylinder 6 and consequently the piston 3 of thecontrolling valve upward, that is to say, draws the piston 3 into its mid posii of the cylinder 17 is greater.

niece tion; The closing movement of the main admission valves or the like is momentarily interrupted. Now it is to be understood that the travel of the controlling valve is intended to be very small as compared with that of the rod 10 or the sleeve of the centrifugal governor v1, for instance only as 1 to 20. llnthis case a fall in the speed of rotation of 1/20th of the amount of the degree of nonuniformity of the spring governor (amounting say,to a that is to say, a fall of only about 1/ 5th of the speed 71 will sullice to bring about the return of the controlling piston 3 to its mid position as hereinbefore described.

As indicated in Fig.- 5 the speed falls from the value a only by the very small amount between that point and n where a fresh state of repose isset up and at which point the main admission valves or the like are open by the amount U Now if the device constituting the invention had not been employed the speed would have fallen to the value a and beyond. The closing movement of the admission valves would have continued for a correspondingly long period, that is to say, up to the time t, at which point the amount of admission of the prime mover would have already become far too small, with the result that a permanent oscillation or hunting action would be set up in a well-known manner, as indicated by the dot and dash lines in Fig. 5.

.ln the fresh state of repose before referred to'at the point t the dash pot piston 7 occupies relatively to its cylinder 6 the position shown in Fig. 3 in which it is displaced in a downward direction and which is accordingly not identical with the mid position shown in Fig. 1. speed a will in general be by such an amount higher than the original speed n as would not be admissible for instance for driving electric generating machines. lt is however possible to restore the original speed 11. for the new state of repose if the dash pot be constructed as shown in Fig. 6 and substituted for the simple dash pot shown in Fig. 1. ln this construction it is only in its middle portion that the bore or internal diameter of the dash pot cylinder 17 is made sulliciently small to correspond exactly to the dash pot piston 18. Above and below this portion the internal diameter Bearing against the shoulders thus formed are freely fitting rings 19 and 20 loaded by springs 21 and 22. Now upon the piston 18 being forced downward out of its mid position by the centrifugal governor owing to a reduction in the load on the water driven turbine,

it will force the ring 20 downward and ac-' cordinrgly compress the lower spring 22, see Fig. 7. The upper spring 21 remains in its previous position as its supporting ring Moreover the new 19 rests against the shoulder formed by the constructed part of the casing 17. Owing to the one-sided or unbalanced action of the spring 22 the piston 18 is no longer in equilibrium relatively to the cylinder 17 and the spring 22 tends to force the piston back relatively to the cylinder 17 into the mutual mid position shown in Fig. 6. A mutual action will now take place in governing mecha' nism fitted with a dash pot constructed in this manner, betweenthe centrifugal govbeen caused to run at its original speed. In

this way the turbine will be "seen to have been provided with means for governing at constant speed. The action of the arrangement is illustrated graphically in Fig. 8. Up to the time t the initial state of respose or dwell has lasted with a certain load. The speed during this period amounted'to n and the main admission valves or the like of the turbine were opened by the amount 0 After the reduction in "load the speed of the turbine rises to-the amount a and then falls to the amount at. Up to this point the action is identical with that already described with reference to Fig. 5 up to the time 25 Now however the action of the compressed spring 22 comes into play. The

dash pot cylinder 17 and along with it the controlling piston 3 are pushed downward slightly by the action of this spring and only slowly or just at such a speed'as allowed by the small perforation in the dash pot piston 18, thus allowing the auxiliary motor to con tinue its closing movement. As a result the speed falls from the amount a (Fig. 8),

which corresponds to the amount of in Fig. 5, still further and the controlling piston 3 is returned to its mid position owing to the falling of the governor sleeve caused thereby. Let this state of things be supposed to have been attained at the time F. The main admission valves are then open by the amount 0 which is somewhat less than the l l amount corresponding to the new load at the normal speed. The speed has momentarily the value 12, and owing to the slightly too small amount of opening of the main ad mission valves is constantly falling. This would at once again bring about an opening movement were it not for the fact that the dash pot cylinder 17 together with the controlling piston 3 is further displaced relatively to the dash pot piston 18 in the direc- 1 tion of closing under the action of the spring 22. By properly proportioning the size of the perforation in the dash pot piston 18 it is possible to insure that the upward movement'of the piston 18 caused by the falling of the sleeve of the spring governor and the downward movement of the dash pot cylinder relatively to the dash piston will neutralize each other, so that the controlling piston 3 will remain in its mid position until the ring 20 again bears on the shoulder formed by the portion of the dash pot cylinder 18 of reduced diameter and the one sided action of the spring 22 ceases to exist. At this moment the continued falling of the speed causes the main admission valves of the water driven turbine to be again opened, to an extent 0 corresponding tothe new load, with the result that at the time t the new state of repose or dwell is attained. As in this new state of repose the dash pot piston 18 again occupies the same position relatively to the dash pot cylinder 17 as at the-time t before the beginning of the governing operation, the position of the governor sleeve will also be the same, and the speed a after the close of the governing operation will be equal to the speed 17, before the latter.

Fig. 9 shows how it is possible, ascompared with the simpler governing mechanism illustrated in Fig. l, to arrange between the auxiliary motor, or in effect the main governing shaft 16, and the lever 8 of the centrifugal governor, instead of the dash po't 6, 7 shown in Fig. 1, not. only the dash pot shown in Figs. 6 and 7 fitted with returning springs, but in addition thereto which in itself is known. Th

areturning linkage system of a' construction is arrangement has for its object to establish a certain relation "of dependence, necessary for certain power-supply services, between the load on one hand and the speed on the other. For the sake of simplicity in Fig. 9 all parts that are similar in the arrangements shown in Fig. 1 and Fig. 6 respectively are denoted by the same numbers as already used in those figures. In the arrangement shown in Fig. 9 the pivotal axis 9 of the governor lever 8 is no longer stationary or fixed, as

in Fig. 1, but is carriedon the returning ing displacement or dwell of the point .9

during a governing operation has the effect of com elling the sleeve of the spring governor to assume a different POSitlOII .in order to set up a new state of repose, with the result that a lasting alteration on the speed obtains in the case of the new load. Now the difference in the speed between of the spring governor 1 must occupy a higher position after the close of a governing operation with the result that a higher speed will correspond to the new lighter .-load (positive returning). If the link 27 be arranged in the dotted line position 27, the point 9 will be lowered at every closing novemeht of the shaft 16, thus causing the sleeve of the spring governor to occupy a lower position after the governing operation. The speed will then be less than before for the new, lighter load (negative returning). In all these cases a method of governing practically free from oscillation or hunting is also obtained by means of apparatus forming the subject matter of the lnvention. A governing operation in general takes place in a perfectly similar manner to what has been hereinbefore described in reference to constant speed governing without returning mechanism, Fig. 8. The only difference consists .in the fact that a greater or lesser displacement of the dash pot piston 18 in the dash pot cylinder 17 takes place during a governing operation, other conditions being equal. The amount of displacement will be less when the movement imparted to the rod 10 by the returning mechanism is in the opposite direction to that caused by the centrifugal governor, as is the case in positive returning. The amount of the displacement will be greater when the movements of the returning mechanism and the centrifugal governor .act in the same direction on the rod 10.

The course of a governing operation with positive and negative returning arrangements respectively is illustrated diagrammatically in Fig. 10, the full line curves applying to positive and the dash-and-dot curves to negative returning arrangements. In the case of the positive returning arrangement the speed a attained at the time at the close of the governing operation is higher by a certain amount than the speed n before the lightening of the load. Conversely. in the negative returning ar-' rangement the speed a during the subsequent period of dwell and which is attained at the time t is less by a certain amount than that obtaining before the reduction in load.

In all the cases hereinbefore described it is essential toward attaining freedom from oscillation or hunting in governing mechanism that the controlling piston 3 shall be nieaaea returned to its mid position by the dash pct 17 .to 22 immediately after the change in the speed has been set up, and that this shall necessitate only a very small backward movement or reverse change in the speed and only a very brief period of time, by which means it state of equilibrium (which always prevails at the time when the change in the speed takes place) between the amount-of energy supplied to the prime mover and the amount of power furnished by the latter, to be maintained at least approximately constant until the close of the governing opertions.

The returning spring 21 shown in Fig. 6 comes into action when the load on the turbine is increased, the spring 22 then remaining inoperative. The dash pot cylinder may in some cases be filled with water, air or the like, instead of oil. As an alternative, th springs may be arranged externally to thedash pot cylinder and act on the piston rod instead of on the piston itself as has been shown in Fig. 11. The springs 3.4 rest with their one end on the outside of the dash pot cylinder while the upper end of the upper spring is fixed to the rod of the controlling linkage system that is connected to the dash pot piston and the lower end of the lower spring is fixed to the rod of the controlling linkage system that is connected to the controlling valve for the auxiliary motor. The working of this dash pot is the same as the working described with reference to Fig. 6.

If desired some other device equivalent in action to a dash pot for instance a friction coupling, may be employed instead of a dash pot sucha friction coupling has been shown in Figs. 12 and 13. The rod 35 of the controlling linkage system, intercalated between the centrifugal governor and controlling valve, that is connected to the controlling valve carries at its upper end a piston 36 guided by two guide shoes 37 and 38 within a cylindercasing 39. The two guide shoes are arranged opposite to each other in the same diameter and are pressed by means of springs 40 and 41 toward the piston 36. The casing 39 is hanged up to the rod 42 of the controlling linkage system. The working of such a friction coupling is the same as the Working of a dash pot. Upon the centrifugal governor being caused to rotate at a higher speed owing to the load on the prime mover being lightened, the rod 42 presses the cylinder casing 39 downward.

The friction of the guide shoes 37 and 38 is so great, that in the short period of the movement, which is momentarily in a downward direction, it is not possible to overcome this friction and to admit of the piston moving relatively to the two guide is rendered possible for theshoes. A momentary driving connection is accordingly set up between the piston 36 and the controlling valve and consequently the piston 6 of the controlling valve will also be pressed downward till its sitting upon the lower stop of the valve casing. From this moment by a further downward movement of the the guide shoes will be overcome, this being possible by the yielding nature of the friction coupling. By an occurrent upward movement, the friction coupling will act as a rigid connection till the piston 6 has reached the upper stop of the casing.

Claims: v

1. In a governing mechanism for prime movers the combination of a main governor shaft, an auxiliary motor acting upon said shaft, a controlling organ for said auxiliary motor traveling only within relatively narrod 42, the friction of row limits, a centrifugal, governor, a con trolling linkage system connecting said governor with said controlling organ, a yielding member in connection with said linkage sys tem capable of continuing its travel after the controlling organ has reached its end positions, said yielding member being capa ble of imparting to the controlling organ, upon a reversing movement of the governor, the same degree of movement, substantially as described and for the purpose set forth.

2. In a governing mechanism for Waterdriven turbines the combination of a main governor shaft, a hydraulic auxiliary motor acting upon said shaft, a controlling valve for said auxiliary motor traveling within relatively narrow limits, a centrifugal governor, a controlling linkage system connecting the centrifugal governor with the controlling valve, a yielding member in connection with said linkage system capable of continuing its travel after the controlling valve has reached its end positions, said yielding member being capable ofimparting to the controlling organ, upon a reversing movement of the governor, the same degree of movement, substantially as described and for the purpose set forth. I

3. In a governing mechanism for prime movers the combination of a main governor shaft, an auxiliary motor acting upon said shaft, a controlling organ for said auxiliary motor traveling only within relatively narrow limits, a centrifugal governor, a controlling linkage system connecting said governor with said controlling organ, a dash pot in connection with the controlling linkage system and consisting of a cylinder and a perforated piston therein, substangiallly as described and for the purpose set ort 4. In a governing mechanism for waterdriven turbines the combination of a main governor shaft, a hydraulic auxiliary motor said casing,

mg member acting upon said shaft, a controlling valve for saidauxiliary motor traveling Within relatively narrow limits, a centrifugal governor, a controlling linkage system connecting the centrifugal governor Withthe controlling valve, a dash pot in connection with the controlling linkage system and consisting of a cylinder'and a perforated piston therein, substantially as described and for the purpose set forth.

In a governing mechanism for' Waterdriven turbines the combination of a main governor shaft, a hydraulic auxiliary motor comprising a casing and differential pistons acting upon said shaft 1 and a pipe system for fluid under pression in connection with a controlling valve with stops intercalated in said pipe system, a centrifugal governor, a controlling linkage system connecting the centrifugal governor With the controlling valve, a dash pot intercalated in the controlling linkage system and consisting of a cylinder and a perforated piston therein, substantially as described and for the purpose set forth.

In a. governing mechanism for prime movers the combination of a main governor shaft, an auxiliary motor acting upon said shaft, a controlling organ for said auxiliary motor traveling only within relatively narrow limits, a centrifugal governor, a controlling linkage system connecting said governor with said controlling organ, a yieldin connection with said linkage system capable of continuing its travel after i the controlling organ has reached its end positions, said yielding member being capable of imparting to the controlling organ, upon a reversing nor, the same degree of movement, springs movement of the goverprovided in connection with said yielding member acting to return it in its mid positionafter each displacement for restoring after each governing the given position of the controlllng organ in dependence upon the centrifugal governor, substantially as described and for the purpose set forth.

I controlling valve in 7. In a governing mechanism for waterdriven turbines the combination of a main. governor shaft, a hydraulic auxiliary motor acting upon said shaft, a controlling valve for said auxiliary motor traveling within relatively narrow limits, a centrifugal governor, a controlling linkage system connecting the centrifugal governor with the controlling valve, a dash pot jntercalated in the controlling linkage'system and consistmg of a cylinder and a perforated piston therem, springs provided in connection with the dash pot and acting to return the dash pot cylinder after each displacement to its mid position for restoring after each governing the given position of the controlling valve in dependence upon the centrifugal governor, substantially as described and for the purpose set forth.

8 In a governing mechanism for waterdriven turbines the combination of a main governor shaft, a hydraulic auxiliary motor comprising a casing and differential pistons acting upon said shaft and a pipe system for fluid under pression in connection with saidcasing, a controlling valve with stops intercalated in said pipe system, a centrifugal governor, a controlling linkage system connecting the centrifugal governor with the controlling valve, a dash pot intercalated in the controlling linkage system and consisting of a cylinder and a perforated pistontherein, springs provided in connection with the dash pot and acting to return the dash pot cylinder after each displace.- ment to its mid position for restoring after each governing the given position of the dependence upon the centrifugal governor, substantially as described and for the purpose set forth.

In testimony that I claim the foregoing as my invention, I have signed my name in presence of two subscribing witnesses.

ANTON GAGG.

Witnesses ERNST FISCHER, CARL GUBLER.

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