US1960051A - Governing mechanism for elastic fluid turbines - Google Patents

Description

May 22, 1934- F. R. ERlcsoN GOVERNING MECHANISM FQR ELASTIC FLUID TURBINES Filed June 25. 1933 W. MW 3 E 9 mm m 3 4: o mw 2 2 Mn m 02 7 w* a n 2 3w Wu a Willard/l Inventor: FranKlin R.Er-icson,

by His tLorneg.

Patented May 22, 1934 TES PATENT;

GOVERNING MECHANISM FOR ELAS'IH) FLUID KURBINES New York Application June 23, 1933, Serial No. 677,185

4 Claims.

The present invention relates to the governing or regulating of elastic fluid turbines, and especially to elastic fluid turbines of the type wherein the turbine is governed or regulated in terms of an operating condition other than the speed of the machine, for example, in terms of the pressure or temperature of the elastic fluid exhausting from the turbine. The usual condition met with is one wherein the turbine is regulated in terms of the pressure of the exhaust elastic fluid,

' such turbines being termed commonly back pressure turbines. Accordingly, I have herein specifically illustrated and described my invention in connection with a back pressure turbine. It is 5 to be understood, however, that this is only by 'way of example and that the invention is not limited necessarily to such turbines.

In utilizing back pressure turbines, the speed of the turbine is fixed by means independent of the load on the turbine, for example, in the case i of a turbine driving an alternating current generator, by tying the alternating current generator to a main line of fixed frequency. That is to say, the generator driven by the turbine is connected in parallel with another generator or generators regulated in terms of load.

In the operation of back pressure turbines, the exhaust elastic fluid is utilized usually for industrial purposes and for this reason-it is desirable to maintain the back pressure as nearly constant as possible since pressure variations may affect adversely the industrial processes for which the elastic fluid is utilized.

The object of the present invention is to provide an improved governing or regulating means for a turbine of the type referred to whereby the back pressure or other operating condition of the turbine will be maintained substantially at a constant value.

For a consideration of what I believe to be novel and my invention, attention is directed to the following specification and the claims appended thereto.

"In the drawing, the figure is diagrammatic view of an elastic fluid turbine having a governing mechanism embodying the invention.

In the drawing, no effort has been made to show the several parts in correct relative positions, the several parts being separated and located in a manner to illustrate the principles of the invention.

Referring to the drawing, 1 indicates an elastic fluid turbine provided with an inlet conduit 2 and an exhaust conduit 2 Elastic fluid from the exhaust conduit may be utilized for any desired purpose, the turbine being regulated in a manner to supply the requirements for exhaust elastic fluid.

In inlet conduit 2 is a valve means 3 which controls the supply of elastic fluid to the turbine. 60 Valve means 3 has a stem 4 pivoted to a lever 5 supported at one end on a fixed fulcrum 6. The other end of the lever 5 is provided with a roller 7 which engages a cam 8 carried by a shaft 9.

On shaft 9 is a pinion 10 which meshes with a rack 11 on the upper end of a rod 12. The lower end of rod 12 is connected to a piston 13 located in a cylinder 14. Located between piston 13 and the top wall of the cylinder is a spring 15 which acts in a direction to force piston 13 downwardly in the cylinder. When piston 13 moves upwardly, cam 8 is turned in a direction to open valve means 3 and when piston 3 moves downwardly, cam means 8 is turned in a direction to permit valve means 3 to close. Admission of actuating fluid to cylinder 14 is controlled by a pilot valve 16 of usual construction. The pipe through which actuating'fluid is supplied to the pilot valve is indicated at 1'7 and the discharge pipe from the pilot valve is indicated at 18. The flow of actuating fluid from pipe 1'? to cylinder 14 and from cylinder 14 to discharge pipe 18 is controlled by the two pilot valve heads 19 and 20 respectively. When the pilot valve is raised above normal position, actuating fluid is admitted from pipe 17 to the underside of piston 13 to lift it and move valve means 3 toward open position, and when the pilot valve is lowered below normal position, actuating fluid is permitted to escape from beneath piston 13 through discharge pipe 13, permitting piston 13 to move downwardly and move valve means 3 toward closed position. The supply of actuating fluid to pipe 17 may be taken from any suitable source of pressure. Usually, in the case of an elastic fluid turbine, oil pressure supplied by a pump driven from the turbine shaft is utilized, it being the pump which supplies .oil to the bearings also. The stem of the pilot valve is pivoted to one end of a lever 21 fulcrumed at 22. The other end of lever 21 is pivotally connected by a link 23 to a floating lever 24. One end of lever 24 is pivotally connected by a link 25 to rod 12. The other end of floating lever 24 is pivotally connected by a link 26 to one end of a lever 27 pivoted on the fixed fulcrum 28. The 105 other end of lever 2'7 is pivotally connected to one arm of a head 29 on the upper end of a stem 30. Stem 30 is connected to a piston 31 which moves in a cylinder 32. Located between the upper side of piston 31 and the top wall of cylinder 32 is a 110 spring 33 which tends normally to move piston 31 downwardly in cylinder 32.

Connected to cylinder 32 is a pilot valve casing 34 in which is arranged a pilot valve head 35 which controls flow of fluid pressure to and from cylinder 32. Connected to pilot valve head 35 is a stem 36 which at its lower end is connected to a speed governor lever 37. One end of lever 37 is connected to a speed governor 38 driven from the turbine shaft through suitable gearing 39. For the sake of clearness, the speed governor is shown diagrammatically and not in correct relation to the turbine. It will be understood, however, that the speed governor will be driven from the turbine shaft in a usual way. When the turbine is operating on back pressure control, governor 38 is set to function as a pre-emergency governor, pilot valve head 35 being out of line with the passage leading to cylinder 32.

The other end of lever 37 is pivotally connected to a stem 39 fixed to piston 31. Connected to pilot valve casing 34 is a fluid pressure supply pipe 40 and a fluid pressure discharge pipe 40 In fluid pressure supply pipe 40 is a second pilot valve casing 41 in which is located a pilot valve head 42. Connected to pilot valve casing 41 is a supply conduit 43 which is connected to the same source of fluid pressure as is the supply pipe 17. Also, connected to pilot valve casing 41 is a discharge pipe 44. Normally, when the turbine is on back pressure control, pilot valve head 42 covers the end of pipe 40, thereby shutting off the flow of fluid pressure from pipe 43 to pipe 40 and thence through pilot valve casing 34 to cylinder 32. When pilot valve head 42 is lowered,

actuating fluid is admitted through pipe 43 to pipe 40 and when pilot valve head 42 is raised, actuating fluid is permitted to escape from pipe 40 through the discharge pipe 44.

Pivotally connected to the other arm of head 29 is a lever 45 mounted on a fixed fulcrum 46. The other end of lever 45 is pivotally connected to the upper end of a stem 47 which at its lower end is connected to the movable member 48 of a pressure responsive device. In the present instance,

a movable member 48 is shown as being in the form of a corrugated bellows. It is mounted on casing 49, its upper end being connected to a flange 50 inside the casing. The corrugated bellows 48 and flange 50 serve to divide casing 49 into two compartments, an upper compartment 51 and a lower compartment 52. Compartments 51 and 52 are connected to each other by. an opening 53 in flange 50, the area of which opening may be regulated by means of an adjustable valve member 54. Lower compartment 52 is connected by a pipe 55 to a casing 56 in which is mounted a corrugated bellows 57. Connected to corrugated bellows 57 is a rod 58, the upper end of which is pivotally connected to a lever 59 pivoted at one end on a fixed fulcrum 60. At an intermediate point, lever 59 is connected by a link 61 to one end of a floating lever 70. The other end of floating lever is connected by a link 71 to a lever 72 pivoted on a fixed fulcrum 73. On the'free end of lever 72 is an adjustable weight 74. Connected to lever 72 is the stem 75 of a pressure responsive device comprising a casing 76 in which is located a corrugated bellows 77, the lower end of stem 75 being connected to the bellows. Casing 76 is connected by a pipe 78 to exhaust conduit 2 so that the pressure responsive device comprising casing 76 and corrugated bellows 77 is subjected to the pressure in exhaust conduit 2 In pipe 78 is a liquid seal 79. Also, in pipe 78 be- '1 tween the liquid seal and casing 76 is an orifice 80, the area of which may be adjusted by means of a valve 81.

Surrounding stem 75 between the top wall of casing 76 and an adjustable collar 82 on stem 75, is a governor spring 83, the tension of which may be adjusted by varying the position of collar 82. Spring 83 has an appreciable gradient so that it gives a gradient to the pressure responsive device comprising casing 76 and corrugated bellows 77, these parts forming in substance a pressure responsive governor. By having an appreciable gradient is meant that appreciable successive increases in pressure are required to compress bellows 77 successive steps against the action of spring 83.

Pilot valve head 42 is connected to floating lever 70 by a stem 84. Located between the top of pilot valve casing 41 and adjustable collar 85 on stem 84 is a suitable spring 86 which acts normally in an upward direction.

Associated with lever 59is a yielding means which serves normally to hold lever 59 always in the same position. In the present instance, this means is shown as comprising a rod 87 pivotally mounted at its lower end on a fixed fulcrum 88 and projecting upwardly through an opening in lever 59. On rod 87 are upper and'lower adjustable collars 89 and 90 between which and lever 59 are located suitable springs 91 and 92. Springs 91 and 92 act in opposition to each other and when in balanced position hold lever 59 in a fixed position which position may be adjusted by varying the positions of collars 89 and 90 relatively to each other.

Casing 49, pipe 55, and casing 56 are filled with a liquid, such as oil which functions as a hy-- draulic means for transmitting motion between bellows 48 and 57. Opening 53 forms a passage of restricted area between chambers 51 and 52 in casing 49, permitting restricted flow of liquid from one chamber to the other. When bellows 48 moves downward, it forces liquid from casing 49 through pipe 55 to casing 56, thus causing bellows 57 to move upward. But little liquid will flow through orifice 53 because of its restricted area. In a similar manner, when bellows 48 moves upward, it causes passage of liquid from casing 56 through pipe 55 to casing 49, thus effecting downward movement of bellows 57.

The operation is as follows: Assume that the turbine is running, valve means 3 being open a predetermined amount, and is supplying elastic fluid through exhaust conduit 2 sufficient to meet the existing demand for exhaustelasticfluid. The

speed of turbine 1 is set by some external means such as by having its generator tied in with other generators, the turbines for which are maintained at constant speed so as to hold constant frequency on the line. A certainpredetermined pressure obtains in conduit 2 38 is set for a speed a predetermined amount higher than normal operating speed so that it is normally inoperative, functioning as a pre-emer gency governor. Under these circumstances, pilot valve head 35 in pilot valve casing 34 occupies a position above the passage connecting pilot valve casing 34 to cylinder 32 so that pipe 40 is connected directly through pilot valve casing 34 to the underside of piston 31 in cylinder 32. The other parts may occupy positions such as those indicated in the drawing, lever 59 being held in the position shown by the springs 91 and 92, which tend always to maintain it in such a position. Weight 74 and spring 83 are set for the desired exhaust pressure in conduit 2 Speed governor Assume now that the pressure in exhaust conduit 2 decreases, which indicates an increase in the demand for exhaust elastic fluid and requires opening movementof valve means 3 in order to supply the additional exhaust elastic fluid called for. Reduction of pressure in conduit 2 reduces the pressure in casing 76 whereby the resultant action of weight 74 and spring 83 eflects a downward movement of bellows 77,- thus lowering the right hand end of floating lever 70. This lowers pilot valve head 42, thereby admitting fluid pressure from pipe 43 through pipe 40 and pilot valve casing 34 to the underside of piston 31, lifting piston 31 against the action of spring 33. Upward movement of piston 31 effects downward movements of the right hand end of lever 27 and of the left hand end of lever 45.

Lowering the right hand end of lever 27 lifts pilot valve'heads 19 and 20, thereby admitting fluid pressure through pipe 17 to the underside of piston 13, effecting upward movement of piston 13 in cylinder 14, and thereby opening somewhat valve means 3 to supply additional elastic fluid to turbine When piston 13 moves upward, it restores pilot valve heads 19 and 20 to normal position through the follow-up connections comprising link 25 and floating lever 24.

Lowering the left hand end of lever 45 serves to expand bellows 48 in casing 49, thus increasing the fluid pressure in the system comprising casing 49, pipe 55 and casing 56 and effecting upward movement of corrugated bellows 57 in casing 56. Upward movement of bellows 57 lifts the left hand end of lever 59, thereby tending to restore pilot valve head 42 to normal position where it covers the end of pipe 40. Restored to this position, the parts are again in equilibrium but because of the gradient of spring 83, the new positions of the parts, that is the new positions of bellow 77 and levers 72, 70 and 59 correspond to a different and somewhat lower pressure in exhaust conduit 2 To restore the pressure in conduit 2 to the desired normal value requires that valve means 3 be opened further so as to supply more elastic fluid to the turbine. In this connection, it will be understood that since spring 83 has an appreciable gradient, each position of bellows 77 and of lever 59 corresponds to a certain definite pressure in exhaust conduit 2 Therefore, after these parts have assumed new positions, because of a change in demand for exhaust elastic fluid, it becomes necessary to restore them to their original positions in order to readjust valve means 3 and bring the pressure in exhaust conduit 2 back to normal value. This action is effected by means of the spring 91 and 92 acting on lever 59.

When the left hand end of lever 59 is lifted, it increases the pressure of spring 91 and decreases the pressure of spring 92, whereby there obtains an unbalanced pressure between the two springs acting on lever 59. This unbalanced pressure tends to restore lever 59 to its normal position as shown in the drawing and hence tomove pilot valve head 42 in a direction to effect opening movement of valve means 3. Movement of lever 59 to normal position by the action of the unbalanced springs 91 and 92 is regulated by the flow of fluid through restricted orifice 53 which is set so that only a slow return movement of lever 59 can take place. In other words, the fluid system including orifice 53 forms in substance a dash pot which functions to delay the return of lever 59 to its normal balanced position under the action of springs 91 and 92. As a result, after there has been an operation of valve means 3 due to the decrease in pressure in exhaust conduit 2 a readjustment of the position of valve means 3 will take place gradually due to the return of lever 59 to normal position so that eventually the pressure in exhaust conduit 2 will be restored to the predetermined desired value.

In case of an increase in pressure in exhaust conduit 2 which indicates a decrease in demand for exhaust elastic fluid, an operation similar to that just described takes place except in the opposite direction, valve means 3 being finally adjusted to a position wherein with the then existing demand for exhaust elastic fluid, valve means 3 occupies a position such that the exhaust elastic fluid will be supplied at the predetermined desired pressure.

If for any reason, the back pressure governor mechanism ceases to function, then upon increase in speed to a value a predetermined amount above normal, speed governor 38 will come into action and take control of the governing of the turbine.

By my invention, it will be seen that I provide a governing means for use in connection with an elastic fluid turbine such as a back pressure turbine, whereby I am enabled to maintain constant pressure, for example, in the exhaust conduit of the turbine, and at the same time obtain stable operation of the mechanism.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. In combination, an elastic fluid turbine, valve means controlling the flow of elastic fluid thereto, a pressure responsive device having a governor spring with a predetermined gradient, a pipe connecting the pressure responsive device to the exhaust conduit of the turbine, a pilot valve connected to be moved by said pressure responsive device, the cormections comprising a lever and spring means tending to restore said lever to a predetermined position, a fluid actuated device to which said pilot valve controls the admission of actuating fluid, means connecting the fluid actuated device to said valve means to effect positioning of said valve means, a casing, means including a movable wall dividing said easing into two chambers, a passage of restricted area connecting said chambers to each other, means providing a second movable wall, fluid means for transmitting movement from the first named L movable wall to the second named movable wall, means connecting said first named movable wall to said fluid actuated device, and means connecting said second named movable wall to said lever.

2. In combination, an elastic fluid turbine, valve means controlling the flow of elastic fluid thereto, a movable governing device having a governor spring with a predetermined gradient, means responsive to an operating condition of the turbine other than its speed for effecting movement of said movable governing device, a pilot valve connected to be moved by said movable governing device, the connections comprising a lever and spring means tending to restore said lever to a predetermined position, a fluid I thereto, a movable governing device having a governor spring with a predetermined gradient, means responsive to an operating condition of the turbine other than its speed for effecting movement of said movable governing device, a pilot valve, a floating lever to which said movable governing device and said pilot valve are connected, yielding spring means connected to the floating lever tending always to restore one end of it to a predetermined position, a fluid actuated motor to which said pilot valve controls the admission of actuating fluid, means connecting said fluid actuated motor to said valve means for positioning the valve means, means connecting said fluid actuated motor to said floating lever for positioning said pilot valve against the action of said yielding spring means, and for delaying return movement of said floating lever under action of said yielding spring means.

4. In combination, an elastic fluid turbine, valve means controlling the flow of elastic fluid thereto, a movable governing device having a governor springv with a predetermined gradient,

means responsive to an operating condition of the turbine other than its speed for eifecting movement of said movable governing device, a pilot valve, a floating lever to which said'movable governing device and said pilot valve are connected, yielding spring means connected to the floating lever tending always to restore one end of it to a predetermined position, a fluid actuated motor to which said pilot valve controls the admission of actuating fluid, means connecting said fluid actuated motor to said valve means for positioning the valve means, means connecting said fluid actuated motor to said floating lever for positioning said pilot valve against the action of 'said yielding spring means, said connecting means including a plurality of movable abutments and fluid means for transmitting movement from one abutment to the other, and means providing a passage of restricted area through which fluid of said fluid means may be forced by said yielding spring means.

FRANKLIN R. ERICSON.

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