US861054A - Governing mechanism for turbines. - Google Patents

Description

PATENTED JULY 23, 1907.

1?. SAMUELSON. GOVERNING MECHANISM FOR TURBINBS.

APPLIOATION FILED DBO. 19. 1905.

2 SHEETSSHEET 1- MW a Y z I 7 J a s9 5 M F. m J 2 1:1: o 6, O/

No. 861,054; PATENTED JULY 23,1907. P. SAMUELSON. GOVERNING MECHANISM FOR TURBINES.

APPLICATION IIL'ED DEO.19, 1905. I

' 2 SHEETS-SHEET 2.

W/T/VESSES. //vv/vToR.

F5 5 DER/0K SAMUELSON.

UNITED STATES PATENT osrron.

FREDERICK SAMUELSON, OF RUGBY, ENGLAND, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

GOVERNING-,MECHANISM FOB TURBINES.

To all whom it may concern I Be it known that I, Fnnnnmox SAMUELSON, asubject of the King of Sweden, residing at Rugby, England,

v have invented certain new and useful Improvements in Governing Mechanism for Turbines, of which the following is a specification.

This invention relates to throttle valves and more especially to valves working in conjunction with elastic fluid turbine governing mechanism, in which the supply of working fluid to the turbine wheel is roughly regulated by varying the number of inlet nozzles which are open, the finer regulation being attained by means of a throttle valve operating upon an inlet nozzle the full capacity of which is approximately the same'as one of the inlet nozzles.

I have found that the throttle valve is not so sensitive to slight variations in speed as may sometimes bedesired,

. and the object of my present invention is to provide a valve which will operate to admit or cut off more or less of the working fluid on any slight alteration in the speed or load of the turbine taking place.

In the accompanying drawings, Figure 1 is a sectional elevation of a throttle valve constructed according to one modification of my invention; Fig. 2 is a similar view of a second modification; and Fig. 3 is a detail sectional view of valve chest showing separately-actuated admission valves and a throttle valve cooperating therewith. ,7 I

In carrying my invention into effect according to the modification illustrated in Fig. l, I provide a cylindrical valve casing l situated in apassage 2 leading to one of the inlet nozzles 3 of the turbine,'preferably the nozzle next to the last inlet nozzle operated on by the governor so as to preserve the continuity of the stream of fluid supplied to the wheel. The exterior of the valve casing which is hollow is in contact for the greater part of its length with fluid from the source of supply, and is provided at about its mid point with a partition 4 which divides it into two internal cylindrical chambers. The lower of these two chambers is provided with a number of apertures 5 communicating with itsvinterior which form passages for the fluid from the source of.

supply to the inlet nozzle 3. 'lhe passage of fluid through these apertures is controlled by a piston valve 6 which is adapted to move up or down in the lower chamber of the casing 1 to cover or uncover more or less of the apertures 5 according to the amount of fluid required to 'keepthe speed of the turbine normal. The piston valve is connected by a rod 7 passing through the dividing partition 4 to a piston 8 situated in the upper internal chamber, and is operated by said piston in a manner hereinafter described.

The upper chamber in the valve casing is of two differentinternal diameters and the cylindrical body of Specification of Letters Patent. Application 'filed December 19,1905. Serial No. 292,406.

Patented m 23, i907.

the piston 8 is made in two portions of different diameters corresponding to the diameters of the two portions of the chamber as illustrated. The total length of the piston body is less than the length of the casing in which it operates, thereby forming three separate chambers which will be referred to as the upper or chamber 0 the lower or chamber a, the intermediate or chamber b, the intermediate chamber 1) being the annular space between the shoulders 9 on the piston andon the inside of the casing; the upper chamber 0 being the space above the piston and the lower chamber a beingthe space below the. piston. The lower chamber, which is also the smallest, is in direct communication with the fiuid from the sourceiof supply through a small aperture or apertures 10. inthe walls of the valve casing l at its lower jected to fluid atthe same pressure 'as?is supplied to the turbine The piston is provided with acentral aperture 11 extending throughout its length but closed at its lower end, convenientlyby the rod 7 connecting the piston 8 the piston body and terminating at the top-of:the portion of smaller diameter inimediatelyaunder the shoulder 9 formed by the difference. in diameter-betWeenQthe upchamber a by means of. asmallpassage .14 passing verend of the valve casing 1. p

The area of the' upper surface of the largerportion and the areas of thelower surface of the larger portion and that of the lower surface ofthe small portion. of piston 8 are so proportioned that when the pressure in the intermediate chamber b is above that of the exhaust but below that of the source the piston'is hal sure of the fluid on these surfaces, and movement of the throttle valve 6 operated by the piston8 is effected by reducing and increasing the pressure on the lower surface of the larger portion of the cylipdrical pistcn, or in otlifiiivoi-d'sjbfalteringthe pressure. in the interfluid pressure to be admitted or eirliausted fromthe intermediate chamber b. v This pilot valve .is situated in the central aperture 11 of the piston and controls the passage of fluid to the intermediatechamber. v This valve is provided with a head which fits the aperture,

end, so that the-lower side iof the piston isalways sub-;

to the piston valve 6. An ,angularly disposed. passage 12 passingfrom the lower end of the piston Sycommuui- I cates with this centralpassage or aperture ll-which in, turn communicates with the intermediatechamber I) through an aperture 13 passing at right angles through per and lower portions oi the ;piston.- The upper chamher 0 is kept in constant communication with the lower tically through the piston body. I A boss; or extension 15- fomed on the upper .side of the larger portion of" the piston 8 passes through a cap 16 which closes. theuppermediate chamber b. :f'lhis is accomplished by gmeansof a governor operated pilotvalve :17 "which causesanced in any position under the influence of the pres-.

for a short distance and the aperture is enlarged so as speed.

I to provide a passage for the fluid as shown. The valve .stetil lS passes out through the. turbine casing and is connected to one end of a rod or lever 19 operated on by the governor, to the other end of which lever, mechanism, such'as a controller drum, for obtaining the rough regulation of the supply of fluid is attached. The stem 18 of the pilot valve 17 is preferably acted upon by a weight such as 20 or by steam pressure as hereinafter described with reference to Fig. 2 operating against the fiuid pressure on its lower end so as to balance ,it and make it sensitive to slight variations in Referring now to the modification illustrated in Fig. 2. In this case instead'of opposing the fluid pressure acting upon the under side of the pilot valve 17 by a weight secured to the valve stem as described above,

the valve stem has a cylindrical enlargement or piston 21 formed integral with or secured to it. This piston operates in a cylindrical aperture or chamber 22 formed in the cap 16 closing the upper end of the valve casing 1. The chamber 22 is in direct communication through ports23 and 24 formed in the cap 16, with the upper piston chambers and consequentlyreceives fluid at the same pressure at which it is supplied to the turbine. This fiuid acts upon the upper side of the pieton 21 the. area of which is such that the downward pressure produced balances the upward thrust on the rod caused by the fiuid'ac'ting upon the lower side of the pilot valve 17'." The valve stem '13 is continued upward beyond the piston through the cap 16 and is connected to the governor operated'lever 19 as above 'described with reference to Fig. 1.

In'boththe modifications illustrated the cap 16 is pro vided with aninternal chamber 25 into which the fluid irom chamber 1: is exhausted and which is in communicatioh thrbugh "a port or ports 26 with a passage 27 leading to atmosphere, exhaust or a lower pressure stage.

The operation of both modifications of the valve described above is as follows :Duri.ng normal working the piston is balanced and the pilot valve is 'in such a position that it cuts off communication between the central aperture 11 and the intermediate chamber. b. If, however, the speed of the machine varies, the pilot valve is forced up or down by the governorthereby causing V it to uncover the passage 13 leading to the intermediate chamber. If it has been f orced downwards, for example; it establishes communication between said chamber and the passage 27 which mat a considerably lower pressure than the supply, or if it has been lifted it putsfihe intermediate chamber pomrnunication witli' the source of'supply through the central aperture to. In either base the effective pressures on' the various surfaces of :the'piston are immediately unbalanced and the pistortis moved up or down until the passage 13 leading to the intermediate chamber b is again cov-- until there is a further movement up or down of the pilot valve 17. It will be seen from the above that the piston 8 is only balanced when the pressure in chamber 1) is slightly below that of the supply, and that movement of the va lve is caused either by increasing this pressure -by connecting the, chamber to the supply, or

haust.

It is to be noted that the piston follows the movement of the pilot valve, that to say, if the valve takes the valve, when the balanced condition ofthe piston is reestablished. The reverse operation takes place when the pilot valve moves'downward. It is this action which enables the piston to assume positions inderstood, of course, that the pilot valve is usually movdown the throttle valve moves with it, thereby restricting or increasing the area of the apertures 5 through which the-fluid passes to the nozzle to which the valve is fitted.

Where the turbine is supplied with motive fluid at a practically constant pressure either of the above "from the source fluctuat es the modification illustrated in Fig. 2 is preferable. Thisarises from the fact that the weight used for balancing the pressure acting'bn the lower end of the pilot valve should be varied as the pressure of the fluid supply varies. This, however-fie impracticable with a fixed weight whereas with the modification illustrated inFig. 2 any variation in pressure, of the supply fluid acting upwardly on the lower side of the pilot valve is immediately compensated for by ,a similar. variation in the pressure-acting downwardly on the upper side of the piston 21. I e

In Fig.3 is shown a valve chest 30 containing one, two or more admission valves 31- controlling the passage of' motiveffiuid to the nozzles or other discharging be expanding or non-expanding in characterl Each of these valves is separately actuated, as for example, by a piston 33. The movements of the pistons are controlled by pilot valves-not shown-which are-under provisions of the patent statutes,

I have described the principle of operation now considerto r epresent the best embodiment thereand the angularlydisposed'passage 12above referred of; I desire to have it understood that the apparatus shown is only illustrative, and that the invention can be carried out by. other means.

What-I claim as new and desire .to'secure by Letters Patent of the United States, is,- i

1. In a governing mechanism, the;combination of a piston which is normally balanced and is arranged .to assume intermediate posltlons in its cylinder, 21 valve directly connected to the piston 'for throttling the passage of motive fluid by an amount determined by the position of the piston, a casing for the valve, a,governor responsive by decreasing it by connecting the chamber to the exmovesupward the piston does likewise until it over-.

modifications may be employed but where the pressure of my invention'together with the apparatus which I termediate the extreme upper and lower. It is to be uning more or less in one direction or the other in response'to loadchanges. As the piston moves'up or devices 32. Where nozzles are employed they may the control of a shaft governor, preferably, but not to load changes, and a pilot valve located within the piston for creating a'baianced pressure condition on the piston to hold it stationary and an unbalanced condition for moving it, which valve progressively assumes difierent closed positions for each balanced position of the piston.

2. In a governing mechanism, the combination of a throttle valve, a floating piston having upper and loiver surfaces which differ in area and an intermediate surface subjected to inlet and exhaust pressures, and a pilot valve operated by a load-responsive device for controlling the action of the motive fluid on the intermediate surface.

3. In a governing mechanism, the combination of a throttle valve, a hollow cylindrical casing therefor con' tnining chambers of different area, a piston rigidly connected to the valve and located in said casing, the piston being of less length than the casing, conduits for connecting the end chambers in the casing with a source of highpressure fluid, and a pilot valve that connects the intermediate chamber alternately: with the high-pressure source and the exhaust to unbalance the piston and move the throttle valve.

4. in a governing mechanism, the combination of a throttle valve. a piston for operating it which is capable of assuming intermediate positions, a casing for the valve and piston containing end and intermediate chambers, and a balanced pilot valve which is capable of assuming intermediate positions for supplying fluid to the chamber and controlling the exhaust therefrom.

5. In a governing mechanism, the combination of a nozzle. a valve for throttling the supply of fluid thereto to compensate for minor load changes, a piston for moving the valve that is capable of assuming intermediate positions, 8. pilot valve for regulating the piston and having a closed position where the piston is balanced and open positions on opposite sides thereof, where the piston is unbalanced, the position of the-valve when closed progressively shifting from point to point depending upon the position of the piston, and a governor-actuated means for moving the pilot valve over its range of movement.

ii. In at governing mechanism the combination of a fluid discharging device, a valve \vhichthrottles the supply of fluid thereto, a floating piston connected thereto which.

is normally balanced and assumes intermediate positions for different degrees of throttling, ports in the piston, and a pilot valve located within the piston for regulating it and having a closed position where the piston is balanced and open positions where the piston is unbalanced, the said positions of the pilot valve progressively shiftingfrom pointto point depending upon the position of the piston.

7. In a governing mechanism,- the combination of 'a discharge port, a throttle valve for controlling the passage ot lluid through the port, a balanced piston for operating the valve which is capable of assuming intermediate positions. and a. pilot valve for admitting fluid to and cutting it' oit from the piston, which is also capable of assuming intermediate positions, the piston being arranged to follow the direction of movement of the pilotvalve'and restore the balanced condition as to pressure.

S. In a governing mechanism, the combination of a. plurality of ports arranged to discharge motive fluid in the form of an unbroken column, controlling valves therefor, a throttle valve controlling a port at one end of the column, a piston for moving the throttle valve to and fro to compensate for intermediate load changes, which'is capable of assuming intermediate positionsfand a pilot valve controlling the piston which is also capable of assuming intermediate positions.

9. In an elastic-fluid turbine, the combination of a dis charging device, avalve for controlling the passage of fluid thereto, a piston for actuating the valve, and a pilot valve that starts the piston into motion and stops it, the piston and pilot valve being so arranged that a movement of the pilot valve is followed by a movement in the same direction of the piston.

10. In n elastic-fluid turbine, the combination of a plurality of fluid-discharging devices, separately-actuated admission valves therefor, an additional fluid-discharging device, a throttle valve for controlling the passage of fluid therethrongh, means for actuating the admission valves, :1 piston for actuating the throttle valve, and a. pilot valve for nnhalancing the piston when it is desired to move the valve in either direction, and for balancing the piston when it is desired to hold the valve stationary.

In witnesswhereof, I have hereunto set my hand this seventh day of December, 1905.

FREDERICK SAMUELSON.

Witnesses:

Ennnsr HARKER, Ernst. M. WEBB.

Images