US953272A - Governing mechanism for turbines. - Google Patents

Description

0.JUNGGREN.

GOVERNING MECHANISM FOR TURBINES.

APPLICATION FILED AUG. 8, 1907- Patented Mar. 29; 1910.

4 SHEETS-SHEET l.

I /n ventor'z Oscar ULlJ Witnesses.-

ANDREW B. GRAHAM c0 FHOTO-LVTHOGRAFHERS WASMNBTOIL n c.

0. J UNGGREN. GOVERNING MECHANISM FOR TURBINES.

APPLICATION FILED AUG. 8, 1907.

Witnesses:

Ocardungren,

W mif 4 O.JUNGGREN.

I GOVERNING MECHANISM FOR TURBINES.

APPLIOATION FILED AUG. 8, 1907.

Patented Mar. 29, 1910.

' 4 SHEETS-SHEET 3.

M m ntor.- Oscardun Wit n esses new, $3

0.JUNGGREN.

GOVERNING MECHANISM FOR TURBINES.

APPLICATION FILED AUG. 8, 1907.

Patented Mar. 29, 1910.

4 SHEETS-SHEET 4.

/n vendor-.- 0605) Jun UNT'T OSCAR JUNGGREN, OF SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

GOVERNING MECHANISM FOR TURBINES.

To all whom it may concern:

Be it known that I, OSCAR JUNGGREN, a citizen of the United States, residing at Schenectady, county of Schenectady, State of New York, have invented certain new and useful Improvements in Governing Mechanism for Turbines, of which the following is a specification. V

The present invention relates to hydraulic governing mechanisms for elastic-fluid turbines.

It has for its object to improve and simplify their construction.

In the accompanying drawings, which illustrate one of the embodiments of my invention, Figure 1 is a partial View in elevation of a turbine generator; Fig. 2 is a plan view of the same; Fig. 3 is a detail view of the pilot-valve and the follow-up device for restoring it to the normal position after responding to a change in speed; Fig. 4 is an axial section of an oscillating motor for operating the cam shaft to open and close the valves; Fig. 5 is a cross-section of the motor taken on the line 55 of Fig. 6; Fig. 6 is a partial plan view of the motor; Fig. 7 is a perspective View of the motor piston; Fig. 8 is a view in side elevation of the bushing that contains the pilot valve; and Fig. 9 is a section through the pilot valve casing and exhaust pipe therefor.

1 indicates the casing of a turbine of the Curtis type, and 2 the stool for support-ing the generator 3. The generator is provided with a cover 4 having a dome 5 the latter inclosing the speed-responsive device 6 which may be of any suitable character, and is mounted upon the main shaft 7, the latter being common to the rotating members of the generator and turbine. The governor is provided with weights 8 that move toward or away from the axis of the shaft as the speed and load change. This motion is opposed by a spring inclosed by the barrel 9. The resultant motion is conveyed to the governor lever 10. To the outer end of the lever is connected a rod 11 and this rod actuates the pilot valve of the motor, as will appear hereinafter. Steam is admitted to the turbine by one or more conduits 12 that communicate with the interior of the valve chest 18. In some instances one valve chest is suflicient and in other cases two chests will be provided. Mounted on the valve chest is a bracket 14 having bearings in Specification of Letters Patent.

Application filed August 8, 1907.

Patented Mar. 29, 1910.

Serial No. 387,600.

shaft are as many cams as there are valves, and as many valves are provided as may be necessary to properly regulate the turbine under changes in load. The position and relation of the cams on the shaft one to the other will depend upon the direction of movement of the motor piston in response to load changes. Each of these valves is actuated by a bifurcated lever 16 (Fig. 2) which is pivoted at its inner end to a bracket or extension 17, and at its outer end is provided with a roller 18 which rides on a cam directly underneath it. Each valve is provided with an outside spring 19, Fig. 1, to close the same when the cam is rotated in a direction to lower the roller.

Mounted upon the same bracket 14 that carries the cam shaft is a hydraulic motor 20 of the oscillating type. By mounting the cylinder of the motor directly on the bracket and the piston axis concentric with the cam shaft and directly connected thereto, the use of a large number of parts is avoided and there is less danger from lack of alinement or sticking or binding, and since the number of parts is decreased the repairs will be less and the amount of attention required of the station operator will be reduced.

Referring more especially to Figs. 3 and a, 21 indicates the cylinder of the motor which is provided with heads 22 and 23. Mounted within the cylinder is a piston 2& comprising a central or hub portion 25 of steel and a rim portion 26 made of babbitt or other similar material. This is retained in place by screws 27 that are threaded into the hub 25, the babbitt being cast around the screws and afterward finished to the desired dimensions. By making the hub of a separate piece it can be accurately turned to the desired dimension and will be absolutely round and therefore make a good surface to which the stationary abutment in the cylinder may be fitted. By making the piston proper of babbitt it can be taken out and peened to compensate for any slight wear that may take place. The right-hand head 23 is perforated centrally to receive the projecting end of the hub 25 and is beveled at 28 to receive a correspondingly beveled shoulder on the hub. The head 22 is unperforated but is provided with a recess 29 to receive the left-hand end of the hub and which is located a cam shaft 15. On this i form a bearing therefor. Between the head 22, which serves as an abutment, and the hub is a coiled compression spring 30 which serves at all times to press the hub to the right and maintain a tight fit between the conical surface 28 and the cooperating shoulder on the hub. By reason of this construction I am able to dispense with the usual packing glands employed for maintaining tight joints between moving and stationary parts, and by making the head 22 in one piece I avoid the use of a shaft packing at this point.

In any structure of this kind it is desirable to separate the driving from the driven parts with a minimum expenditure of labor. It is also desirable to have some form of connection between the two parts which will compensate for any lack of alinement due to expansion and contraction or to inaccuracy in machine work. To this end the righthand end of the hub 25 is slotted, as best shown at 31, Fig. 7. Secured in this slot is a key 32, Fig. 4, which engages a corresponding slot in the projecting end of the cam shaft 15. The key 32, in addition to uniting the parts and causing corresponding angular movement of the same, acts as a part of the stop for limiting the angular movement of the motor piston thereby preventing injury to the piston. In one position the pin 33 acts as a stop, and in the other position the pin 34.

The admission of fluid to the motor is controlled by a pilot valve located in the casing 35, the latter being formed integral with the head 23, or it may be bolted thereto, as desired. Located inside of the casing or cylinder is a bushing 36 having ports 37 and 38 leading to opposite sides of the stationary abutment 39 in the motor cylinder, and highpressure ports 40 which are always in communication with the admission pipe 41. The admission pipe may be connected with any suitable source of liquid pressure; in

the present instance it is intended to be connected with the same source of supply that lubricates the step-bearing of the turbogenerator. The passage 42 conveys fluid from the port 37 to the under side of the radial abutment 39, as best shown in Fig. 5, while the passage 43 conveys liquid from the port 38 to the upper side of the abut-- ment 39. Located within the bushing 36 is a balanced piston valve 44 the stem of which is extended upward through a guide at the top of the valve casing and is connected to the lever 45, one end of which is pivotally united with the governor lever 10 through rod 11. As the piston valve is moved up or down it admits fluid to the various ports and cuts off the same as occasion demands.

Extending longitudinally of the bushing 36 and between it and the casing are vertical chambers or passages 56 as shown in Figs. 3 and. 9. It will be noted that the bushing is shorter than its inclosing casing, Fig. 3, and hence said chambers or passages are connected at the top and bottom. Both of these chambers exhaust into the discharge pipe 57 as shown in Fig. 9.

In a system of this kind employing high pressure I have found that there is a tendency for the pilot valve to stick under certain conditions. For example, assume that the load is substantially constant for an appreciable interval of time. There is always high pressure between the heads of the pilot valve, while above and below the heads the pressure is that of the exhaust. In the present instance it is atmospheric pressure. There is of course a tendency for the liquid to flow past the heads and escape into the region of low pressure beyond. The fit is made as close as possible between the piston heads and the sleeve, but it is necessary to have a certain freedom of movement at this point, and the parts are also subjected to a slight amount of wear. As the fluid tends to flow from the high-pressure point to the region of low pressure, it forces the pistonhead to one side of the cylindrical bore of the bushing, thus enlarging the space on one side and shutting it off on the other. This brings the metal of the bushing and the heads into direct contact, hence it is nec essary for the governor to overcome this before it can move the valve. To overcome the objection noted I turn grooves in the pistons and leave narrow flanges 46 to reduce the effective side thrust. In other words the side thrust is now due to the area of the flanges and not to the area of the whole piston.

In a construction of this kind it is necessary to provide means for preventing the governor from ovcrtraveling. To this end I mount on the cam shaft 15 a pinion 47 which has the same angular movement as the motor piston. The pinion meshes with a vertically extending rack 48, the rack being held in mesh by a roller 49 engaging the back thereof. The upper end of the rack is connected to the lever 45 which is actuated by the governor. Assuming, for example, that the governor raises the rod 11, and with it the lever 45 about the pivot 50 and the pilot valve, the port 37, which is normally closed, will be open to high pressure, and the port 38, which is also normally closed, will be open to low pressure. As a result, the high-pressure fluid will flow through the passage 42 to the under side of the abutment 39 and move the piston 24 in a clockwise direction, it being assumed of course that the parts were in an intermediate posi tion at starting. Just as soen as the piston begins its movement the pinion 47 will begin to move the rack 48 downward and in so doing move the lever 45 about the pin 50 as' a fulcrum and with it the pilot valve until the ports 37 and 38 are closed, When the motor will stop. In this manner the action of the motor in a sense anticipates the movement of the governor and stops the motor from operating before the governor feels the effects of the change in speed. The same action takes place when the rod 11 is pushed down by the governor lever except that the parts move in the opposite direction.

l/Vhere the machine to be governed is of large capacity, it is preferable to admit steam or other motive fluid at two points on opposite sides of the wheel, as shown in Fig. 2 to equalize the discharge of steam to the bucket wheel or wheels. The valve-actuating mechanism of both steam chests is the same, but only one motor is necessary for operating the parts. In order that a single motor may move both of the cam shafts simultaneously, a pinion 51, Figs. 1 and 4, is mounted on the cam shaft 15, which meshes with a horizontal rack 52 that is guided on its upper side by a roller 53. The rack extends across the machine from side to side, and meshes with a pinion mounted on the cam-shaft 54, Fig. 2, which pinion is in all respects like the pinion 51 on the shaft 15. The rack is held in engagement with the pinion on the shaft 54 by the combined guide and roller By reason of this construction it follows that whenever the camshaft 15 is moved, the cam-shaft 54 is moved by a corresponding amount, and in the same direction.

In accordance with the provisions of the patent statutes, I have described the principle of operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof, but I desire to have it understood that the apparatus shown is only illustrative, and that the invention can be carried out by other means.

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

1. In a governing mechanism for turbines, the combination of a plurality of valves, an oscillating cam shaft for actuating the valves, a motor comprising a stationary member and an oscillating member, the latter being directly connected to the cam shaft and having the same angular movement, a regulating valve for the motor, and a governor responsive to load changes for moving the regulating valve.

2. In a. governing mechanism for turbines, the combination of a plurality of valves, an oscillating cam shaft for actuating the valves, a motor, the movable member of which is directly connected to the cam shaft and has the same angular movement, a regulating valve for the motor, a governor re-' sponsive to load changes for moving the valve, and a device moving with the cam shaft for restoring the regulating valve to its normal position to prevent overtravel.

3. In a governing mechanism for turbines, the combination of a plurality of valves, a cam shaft for actuating the valves, a motor the movable member of which is directly connected to the cam shaft and has the same angular movement, a regulating valve for the motor, a governor responsive to load changes for moving the valve, a pinion driven by the motor, and a rack which is moved by the pinion and restores the regulating valve to prevent overtravel of the motor.

4. In a governing mechanism, the combination of a plurality of valves, a cam shaft for actuating them successively both in opening and closing, an oscillating fluid-actuated motor the movable member of which is in axial alinement with the cam shaft, a means uniting the member and the shaft so that their angular movements are equal, and a governor-actuated means for controlling the motor.

5. In a governing mechanism, the combination of a plurality of valves, a cam shaft for actuating them successively both in opening and closing, an oscillating fluid-actuated motor the movable member of which-is in axial alinement with the cam shaft, a means uniting the member and the shaft so that their angular movements are equal and in the same direction, stops which limit the angular movements of said member in both directions from a given neutral point, and a governor-actuated means for controlling the motor.

6. In a governing mechanism, the combination of a plurality of valves, means for actuating them, a hydraulic motor for driving said means which comprises a cylinder, a radial abutment, a piston the spindle of which is seated fluid-tight in one of the cylinder heads, a regulating valve for the motor, a speed governor for actuating the valve, and a restoring device for the valve to prevent angular over-travel of the motor piston.

7. In a governing mechanism, the combination of a chest, valves therein, a cam shaft for actuating the valves successively, a bracket which supports the cam shaft, an oscillating fluid-actuated motor which is carried by the bracket, a connector for uniting the movable element of the motor and the cam shaft and causing corresponding angular movements, and a governor-controlled valve for regulating the motor.

8. In a governing mechanism, the combination of a valve, a cam and shaft for actuating it, an oscillating motor, mounted in axial alinement with the shaft, a coupling uniting the movable member of the motor with the cam shaft which permits of slight independent axial movements of the motor and cam shaft but looks them against independent angular movements, a regulator for the motor, and a governor controlling the regulator.

9. In a governing mechanism, the combination of chests arranged at separated points on the machine being governed, valves in each chest, a cam shaft for actuating each set of valves, pinions on the shafts, a rack connecting the pinions for insuring corresponding angular movements of the shafts, an oscillating motor concentrically arranged With respect to one of the cam shafts, a means uniting the movable member of the motor With the said shaft, and causing corresponding angular movements thereof, a follow-up device for preventing excessive angular movement of the movable member of the motor and the cam shafts, and a governor for controlling the motor.

10. In a governing mechanism, the combination of a plurality of valves, a lever for operating each of the valves, a cam shaft for moving the levers, an oscillating hydraulic motor comprising a piston and cylinder, the piston being in axial alinement With the cam shaft, a regulating valve, a restoring device for the valve, and a governor for actuating said valve.

11. In a governing mechanism, the combination of a valve, a motor for actuating it comprising a cylinder and an oscillating piston composed of a cylindrical hub having projections thereon and a soft metal portion attached thereto and partially held by said projections, a regulating valve for the motor, and a governor controlling the action of the regulating valve.

In Witness Whereof, I have hereunto set my hand this 6th day of August, 1907.

OSCAR J UNGGREN.

Witnesses:

BENJAMIN B. HULL, HELEN Onronn.

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