US2283127A

US2283127A - Hydraulic turbine governor

Info

Publication number: US2283127A
Application number: US381528A
Authority: US
Inventors: William J Rheingans
Original assignee: Allis Chalmers Corp
Current assignee: Allis Chalmers Corp
Priority date: 1941-03-03
Filing date: 1941-03-03
Publication date: 1942-05-12
Anticipated expiration: 1959-05-12

Description

May 12, 1942.

HYDRAULIC TURBINE GOVERNOR Filed March 3-, 1941 CL USING w. J. RHEINGANS 2,283,127

l atenteci May 12, 1942 l UNITED STATES PATENT OFFICE HYDRAULIC TURBINE GOVERNOR William J. Rheingans, Wauwatosa, Wis., assignor to Allis-Chalmers Manufacturing Company, Milwaukee, Wis., a corporation of Delaware Application March 3, 1941, Serial No. 381,528

12 Claims. (Cl. 253-143) This invention relates generally to prime mover control systems and particularly to systems con-' trolling a prime mover of the type having adjustable runner vanes.

When the prime mover governed is a hydraulic turbine with adjustable runner vanes, it is necessary to adjust the vanes to a steep angle for producing the maximum torque during starting, and it is necessary to make such adjustment automatically. The control system should therefore provide for setting the runner vanes to a steep angle prior to starting and such setting should be relinquished to the normal vane control mechanism at least as soon as the machine is at its normal operating speed. It is also desirable that means be provided by which the steepness of the runner vane setting may be adjusted, by which the speed at which the runner vane setting will change and by which the time at which the runner vanes will be returned to L the normal vane operating mechanism relative er having adjustable runner vanes in which the runner vanes are caused to assume a steep angular position prior to starting of the prime mover to increase the starting torque thereof and are returned to normal position after the starting operation is completed.

Another object of the invention is to provide a control system for a prime mover having adjustable runner vanes in which system the steepness of setting of the runner vanes prior to starting 4 of the prime mover is adjustable.

Another object of the invention is to provide a control system for a prime mover having adjustable runner vanes in which system the runner vanes are set to a steep position prior to starting of the prime mover and in which the speed at which the runner vane setting is changed to the normal position can be readily varied.

Another object of the invention is to provide a control system for a prime mover having adjustable runner vanes in which system the runner vanes are set to the steep position prior to starting of the prime mover and in which the moment at which the setting of the runner vanes takes place relative to the setting of the gate vanes may be adjusted.

Objects and advantages other than those above set forth will be apparent from the following description when read in connection with the accompanying drawing which diagrammatically illustrates a hydraulic turbine of the adjustable runner vane type having applied thereto an automatic speed control system embodying the means for controlling the steepness of setting, the time for changing the setting, and the rate of change in the setting of the adjustable runner vanes accordingto the present invention.

The various elements comprising the control system are not shown in their relative positions, their truesizes, nor in their relative proportions, but are shown diagrammatically to more clearly facilitate explanation of the construction and operation of the system.

Referring more particularly to the drawing by characters of reference, the control system is shown as applied to a prime mover such as a hydraulic turbine generally I designated at [0 and shown as being of the adjustable propeller type driving an alternating current generator I l connectable with and disconnectable from the usual power line by conventional switch gear means well known in the art and therefore not shown. The turbine [0 comprises the casing [2 which forms a peripheral waterfinlet in which are mounted a series of movable vanes l3 forming a gate. The term gate is intended to include means other than those" disclosed and which may be used for the purpose of controlling and guiding the flow of fluid pressure to any prime mover to which the governing system of the present invention is applied. The gate vanes are mounted on stems l4 journaled at the top and bottom in portions of the casing I2. The upper stem portions-extend through the upper portion of the casing to provide for attachment of aconventional linkage connection with a shifting ring [6 which is-adapted to be shifted into different positions and to control the positions of the gate vanes and hence to control the flow of fluid to the turbine. The shifting of ring i6 is connected with and actuated by the piston ll movable within a cylinder .I8,It he piston and cylinder forming a fluid-pressure operated servomotor.

The turbine I0 is connected with the generator I l by a hollow shaft I9 which is supported against movement relative toits axis by a bearing 2| and on which is mounted the turbine runner comprising a hub 22 from which extend, substantially radially, a series of vanes 23, journaled in suitable bearings in the hub. The inner ends of the vanes 23. are severally provided with trunnions 26 and are connected by linkages 21 with a cross head 28 which is guided tov be reciprocated axially of the shaft H) by an operating rod 29. It will be understood that the positions of the runner vanes relative to each other govern the area of the fluid flow passages for openings between the vanes and that adjustment of the runner vanes increases or decreases the area of the flow passages depending upon the direction of the movement of the vanes. The operating rod 29 extends upwardly through the runner shaft l9 and is fixed to a piston 3| movable within a cylinder 32, the piston and cylinder forming a fluid pressure operated servomotor which is mounted in or is formed as a portion of the runner shaft, preferably adjacent the point where the hollow runner shaft is joined to the hollow generator shaft 33. A tube 34 extends through the hollow generator shaft for the purpose of supplying fluid pressure to the servomotor chamber below the piston 3|. A passage 36 about the tube 34, connects with the lower chamber of a distributing head 31 secured to the top of the generator frame and supplies fluid for the downward movement of the piston 3|. The tube 34 is fixed to and rotates with the shaft l9 and supplies fluid pressure for the upward movement of the piston 3| by way of an inclined passage 38 through the piston 3| and is provided with perforations 39 in the portion of the tube extending into the upper chamber of the distributing head 31.

Pressure to the runner vane servomotor 3|, 32 is controlled by a pilot valve 4| which is governed by a pilot valve operating mechanism including an extension 42 from the piston H of the gate operating servomotor I1, I8, connected with an arm 43 fixedly mounted on a rotating shaft 44 and with one arm of a bell crank 45 separately mounted. The shaft 44 has fixedly mounted thereon an arm 46 connected with a rod ,41, the other end of which is connected with a cam 48. The cam 48 is in the form of a bell crank mounted on a fixed pivot point49 and engages a roller mounted on a lever 52 which is pivotally mounted at a fixed point 63 and is biased downwardly at one end by a spring 54 connecting the end of the lever with a fixed point in the control system. The lever 52 is connected by a link 56 with one end of a floating lever 51 to which is connected the stem of the pilot valve 4|. Movement of the gate'servomotor piston |1 transmits motion through

leverage

43, 46 and 41 to the cam 48 from which the motion is transmitted through a second leverage including roller 5|,lever 52, link 56 and lever 51 by which the pilot valve 4| is moved to admit fluid pressure from a pipe 58 through pipes 59 or 6| into the pressure head 31. Fluid from the pressure head 31 is also discharged through the pipes 59 or 6| to a discharge pipe 62. The cam 48 provides means for producing a topographic surface by which a different relation may be obtained between the setting of the gate l3 and the positioning of the runner vanes 23. The cam is preferably made of laminated material to facilitate formation of the proper topographic surface thereof after tests have been made with the entire unit in operation in its final setting.

When the gate opening is small and the runner vanes are in a comparatively flat position, the starting torque of an adjustable propeller type turbine is very low. A relatively long period of time is therefore required to bring the turbine up to the speed at which the unit may be connected to the transmission line. Further, with the runner vanes'in'a relatively flat position, the gate must be opened a relatively large amount to overcome the starting friction of the prime mover unit. It is then necessary to move the gate quickly in a closing direction to prevent over-speeding of the turbine after rotation has begun. Means are therefore provided herein by which the runner vanes may automatically be initially set in a comparatively steep position and then returned to the desired operating angle and particularly in which the degree of such steep positioning, the speed at which the vanes return to the normal operating angle and the moment, relative to the setting of the gate vanes, at which the runner vanes are returned to the normal operating angle, may be adjusted. The one arm of the cam bell crank 48 is connected at the end thereof with a frame 1| to receive the threaded end of a valve stem 12. The threaded portion of the valve stem 12 is provided with nuts 13 and 14 within and adjacent the ends of the frame 1|. The frame 1| cooperating with the nuts 13 and 14 on the valve stem 12 provides a lost motion connection between the cam bell crank 43 and a valve 16. The valve 16 is connected with a source of fluid under pressure by way of a pipe 11 and controls the supply of fluid pressure through a pipe 18 and a needle valve 19 to the cylinder 8| of a servomotor having the piston 82 connected with the end of the lever 52 extend ing. beyond the fixed pivoting point 53 thereof. An adjustable stop 83 extends upwardly through the end of the servomotor cylinder 8|, for the purpose of controlling the degree of movement of the servomotor piston 82 and hence the steepness to which the runner vanes may be set. Discharge of the fluid pressure from the servomotor 8|, 82 takes place by way of needle valve 19, pipe 18 and valve 16 and a discharge pipe 84. Adjustment of nuts 13, 14 controls the moment in the control system cycle at which pressure is supplied to or may discharge from servomotor 8|, 82'and hence controls the moment, relative to the gate setting, at which runner vanecontrol is returned to the normally operating portions of the system. The speed at which the runner vane setting may be changed in either direction is determined by the adjustment of the needle valve 19 which controls the rate of flow of pressure to and from the servomotor 8|, 82.

Means must also be provided by which the runner pilot valve 4| is restored to the neutral or mid-position after each operation of the valve in either direction. The restoring movement is derived from the inner shaft tube 34 by way of a rod 86 extending beyond the fluid distributing head 31 and connecting with one arm of a bell crank 81 pivotally mounted at 88. The other arm of the bell crank 81 is connected by Way of a rod 89 with the floating lever 51 for the pilot valve 4|.

The interconnection of large power generating system in which momentary load fluctuations are relatively small and occur over a relatively large period of time, as compared with the total load, necessitates governing means of extreme sensitivity capable of instant response to the slightest speed variations to maintain adequate distribution stability and proper frequency regulation in the distribution system. Such means are herein shown as comprising a unit including an electric motor connected with and therefore responsive to the frequency (or speed) variations of the prime mover generating unit. The electric motor 9| drives a set of fiyballs 92 which controls a servomotor for imparting motion to a floating lever 93 controlling the operation of a pilot valve 96 which regulates the flow of. fluid pressure to the gate operating servomotor I1, I 8. The structure of the motor operated socalled flyball head herein only diagrammatically illustrated, is shown in detail in U. S. Patent 2,106,684, issued to J. J. Ring and B. R. Nichols and A. Pfau, on January 25, 1938, and will therefore not be further described. Fluid pressure is supplied to the pilot valve 96 through the pipe 58 and is supplied to the two sides of the servomotor piston I! by way of pipes .91 and 98. Fluid pressure is discharged from the servomotor through the valve 96 by way of a pipe 99. Any change in the conditions of the distribution line which results in a change of speed of the motor 9| is immediately translated'into movement of the flyballs 92 which act on the floating lever 93 to change the setting of the pilot valve 96. The gate operating servomotor II, I8 therefore immediately commences to vary the opening of the gate I3 to change the flow of fluid to the prime mover l6 dependent on the degree and the sense of the speed change. Floating lever 93 is connected at one end with one end of a lever IIJI having its other end connected with the stem of the valve body of the pilot valve 96. The lever IIlI is fulcrumed on a nut I62 traveling on a screw I63 which is fixedly mounted and is rotatable either by a hand wheel I04 shown or by other suitable means known.

Movement of the gate servomotor II, I8, must, however, be interrupted before the eifect of-decreasing or increasing speed of the prime mover I would be apparent in the distribution system and hence would produce a change in the speed of the governor motor 9| to thereby prevent over or under regulation or so-called hunting of the unit. Pilot valve 96 must therefore be restored or returned to its neutral or mid-position with a time delay after the operation thereof. Such restoring or compensating means includes the servomotor piston rod extension 42 and the bell crank 45, to one arm of which is connected a rod I06 pivotally connected with the cylinder of a dashpot I61, the structure of which is well known in the art. The piston of the dashpot IOI is connected by a rod I68 with one end of the floating lever 93.

Theentire structure is shown in the position assumed by the various elements thereof at standstill in which the gate is closed and the runner vanes are in the steep tilt position. To place the turbine in operation, synchronizing screw I93 is rotated to raise the end of lever IIJI connected with pilot valve 96, the other end of the lever II'II being retained in its position by its connection with the movable floating lever 93. The valve body of the pilot valve 96 is raised to permit fluid under pressure to flow through the pipe 91 to the left-hand side of the piston I! which moves to open the gate I3 and admit fluid under pressure to act on the runner vanes 23. The runner vanes are already in steep tilt position and the fluid acting thereon therefore immediately produces a high torque to start the prime mover generating unit in rotation. Movement of the piston I1, however, rocks bell crank 43 to pull down on rod I66 and the end of the floating lever 93 to raise the end of lever IIJI connected with floating lever 93, thus returning lever IM to the horizontal position which returns the valve 96 tothe neutral position shown in the drawing. The above sequence of operations is therefore repeated until the prime mover generating unit is atits full' operating speed at which it may be connected with the transmission line in parallel with-other prime mover generating units supplying the line (not shown). When close to'full operating speed, the. motor SH and the flyballs 92 assume control of the pilot valve 96, as is well known.

Movement of the piston I'I mentioned above, also moves arm 46 in a counterclockwise direction to push upwardly on rod 41 which rocks the cam bell crank 48 to pull the frame II toward the right. The frame II moves until the end thereof comes into contact with the nuts I3 and pulls the valve stem I2 of the valve I6 toward the right to shut ofi the pressure inlet 11 and to open the pipe I8 to the discharge or outlet 84. The spring 54 acting on lever 52 depresses the end of such lever and exerts a lifting'forceon the piston 82 which forces fluid out of the cylinder 8I through the needle valve I9 untilthe roller 5I is brought into contact with the surface of the cam 48. Downward movement of the lever 52 and'of the rod 56 depresses one end of the floating lever 51 to move the valve body of the valve 4I into position to (supply pressure by way of the pipe 59 and the passage 36 to'the space above the piston 3I. The piston 3I then moves downwardly to turn the runner vanes into a flatter position.

Downward movement of the piston 3| pulls the end of the floating lever 8! downwardly to raise the end of the floating lever 51 connected therewith which returns the pilot valve M to the midposition and interrupts the flow of pressure to the servomotor 3 I, 32. The prime mover generating unit and the control system therefor are now in the normal operating. condition in which the fiyballs control the action of the gate servomotor II, I8, and the movement of th runner servomotor 3I, 32 is controlled by the position of the cam 48 actuated in response to operation of the gate servomotor II, I8 to maintain a definite relation between the gate opening and the runner vane position.

Shutdown of the unit requires reversal of the above operations generally, and hence requires lowering of the end of lever IIII to shift valve 96 for admitting pressure to the right hand side of the piston II to move gate I3 into the closed position. Movement of the piston II toward the left rocks the lever arm 43 to pull down on the rod 41 which rocks the cam bell crank 48 in clockwise direction. Such movement of the cam bell crank 48 pushes on frame II until the end of the frame comes into contact with the nut I4 and thenmoves valve I6 to the position shown atwhich pressure is admitted by way of the pipe I8 and the valve I9 ,to the upper side of the servomotor M, 82. The piston 82 then moves downwardly until it meets the stop 83 and tilts the lever- 52 to the position shown. Upward movement of the one end of" the lever 52 pulls upwardly on rod 56 to raise one end of the floating lever 51 and to move the valve 4| to the position shown at which pressure is admitted by way of the pipe 6|, the

9| and the flyball head 92 connected with the pilot valve 96 for controlling the servomotor I1,

l8 connected with the gate [3 together with the

leverage

42, 45, I06 I01 and I08 connected with one end of the floating lever 93 for restoring the pilot valve 96 to the neutral or mid-position. The

means for adjusting the runner vanes 23 responsive to the action of the gate operatingmeans includes the arm; acting by way of the rod 41 on the cam bell crank 48 to raise and lower the end of the lever 52 and the rod 56 connected with the floating lever 51 for actuating the valve 4| which controls the flow of'pressure to the servomotor 3|, 32 by way of tube 39 and the

leverage

81, 88 and 89 for restoring the valve 4| to the mid-position. The servomotor BI, 82 controlled by the valve 16 provides means actuated by the gate operating means for causing a temporary starting of the runner vanes 23 at a steep angle and the action of such temporary setting control means is modified by the frame H and the nuts 13 and 14 on the valve stem 12 which form an adjustable lost motion connection for controlling the moment in the cycle of operation of the gate operating means at which the steep setting control means becomes effective and inefiective. Adjustment of the needle valve 19 provides means for adjusting the rate of fluid supply to the servomotor 8|, B2 and therefore provides means for adjusting speed of movement of the vane steep setting control means. The stop 83 limits the movement of the servomotor piston 82 in the steep setting direction and thus provides means for controlling the degree of movement of the steep setting control means. I

Although but one embodiment of the present invention has been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims. 7

It is claimed and desired to secure by Letters Patent:

1. In a control system for a prime mover having a gate controlling the flow of fluid pressure thereto and having a runner with adjustable vanes, means for operating the gate responsive to the speed of the prime mover, means for adjusting the runner vanes responsive to actuation of said gate operating means, a fluid pressure operated servomotor for causing the temporary setting of the runner vanes at a steep angle,a valve actuated by said gate operating means for controlling the flow of pressure to said servomotor, and adjustable means actuated by said gate operating means for controlling said valve to vary the moment in the cycle of said gate operating means of actuation of said servomotor.

2. In a control system for a prime mover having a gate controlling flow of fluid pressure thereto and having a runner with adjustable vanes, means for operating the' gate responsive to the speed of the prime mover, means for adjusting the runner vanes responsive to actuation of said gate operating means, a fluid pressure operated servomotor for causing the temporary setting of the runner vanes at a steep angle, a valve actuated by said gate operating means for controlling the flow of pressure to said servomotor, an adjustable lost motion connection between said gate operating means and said valve and means for adjusting said lost motion connection to vary the moment in the cycle of said gate operating means of actuation of said'servomotorr V 3. In a control system for a prime mover having a gate controlling the flow of fluid pressure thereto and having a runner with adjustable vanes, means for operating the gate responsive to the speed of the prime mover, means for adjusting the runner vanes responsive to actuation of said gate operating means, means actuated by said gate operating means for causing the temporaryrsetting of the runner vanes at a steep angle, and means for adjusting the speed of movement of said vane steep setting means.

4. In a control system for a prime mover having a gate controlling the flow of fluid pressure thereto and having a runner with adjustable vanes, means for operating the gate responsive to the speed of the prime mover, means for adjusting the runner vanes responsive to actuation of said gate operating means, a servomotor actuated by said gate operating means for causing the temporary setting of the runner vanes at a steep angle, and means for adjusting the speed of movement of said servomotor.

5. In a control system for a prime mover having a gate controlling the flow of fluid pressure thereto and having a runner with adjustable vanes, means for operating the gate responsive to the speed of the prime mover, means for advanes, means for operating the gate responsive to the speed of the prime mover, means for adjusting the runner vanes responsive to actuation of said gate operating means, means actuated by said gate operating means for causing the temporary setting of the runner vanes at a steep angle, and means for controlling the degree of movement of said vane steep setting causing means. i

7. In a control system for a prime mover having a gate controlling the flow of fluid pressure thereto and having a runner with adjustable vanes, means for operating the gate responsive to the speed of the prime mover, means for adjusting the runner vanes responsive to actuation of said gate operating means, a servomotor actuated by said gate operating means for causing the temporary setting of the runner vanes at a steep angle, and means for controlling the degree of movement of said servomotor to limit the steepness of setting of the runner vanes.

8. In a control system for a prime mover having a gate controlling the flow of fluid pressure thereto and having a runner with adjustable vanes, means for operating the gate responsive to the speed of the prime mover, means for adjusting the runner vanes responsive to actuation of said gate operating means, means actuated by said gate operating means for causing the temporary settingof the runner vanes at a steep angle, anda stop for controlling the degree of movement of said vane steep setting causing means to limit the steepness of setting of the runner vanes.

9. In a control system for a prime mover hav- I ing a gate controlling the flow of fluid pressure thereto and having a runner with adjustable vanes, means 'foro'perating the gate responsive to the speed of the prime mover, means for adjusting the runner vanes responsive to actuation of said gate operating means, a servomotor actuated by said gate operating means for causing the temporary setting of the runner vanes at a steep angle, and a stop for controlling the degree of movement of said servomotor to limit the steepness of setting of the runner vanes.

10. In a control system for a prime mover having a gate controlling the flow of fluid pressure thereto and having a runner with adjustable vanes, means for operating the gate responsive to the speed of the prime mover, means for adjusting the runner vanes responsive to actuation of said gate operating means, a fluid presmotor for controlling the speed of movement means for controlling the flow of pressure togree of movement of said servomotor to limit the steepness of setting of the runner vanes.

12. In a control system for a prime mover having a gate controlling the flow of fluid pressure thereto and having a runner with adjustable vanes, means foroperating the gate responsive to the speed of the prime mover, means for adjusting the runner vanes responsive to actuation of said gate operating means, a fluid pressure operated servomotor for causing the temporary setting of the runner vanes at a steep angle, a valve actuated by said gate operating means for controlling the flow of pressure to said servomotor, an adjustable 10st motion connection between said gate operating means and said valve, means for adjusting said lost motion connection to vary the moment in the cycle of said gate operating means of actuation of said servomotor, a stop for controlling the degree of movement of said servomotor to limit the steepness of setting of the runner vanes, and a valve arranged between said servomotor and the first said valve to adjust the rate of flow of pressure to said servomotor for controlling the speed of movement thereof.

WILLIAM J. RHEINGANS.