US1824373A - Variable speed governor - Google Patents

Description

Sept. 22, 1931. w. scHMlD VARIABLE SPEED GOVERNOR Filed 0G12. 2l. 1929 INVENTOR W.5chm'|d nl-.W

ATTORNEY Patented Sept. 193,1

UNITED4 sTATas PATENT ori-lcs WALTER scmnn, or rmmmmnu', rmsLvmLa, assioma To wurmcnoun mno'rnrc a nnrurnc'rnmo ooxrm, n concurren or rmmvnlu VARIABLE snm oovnnaroa Application led October 21, 1929. Serial No. 401,218.

My invention relates to a regulating mechanism, more particularly to a speed-responsive governor for a prime mover and it has for its object to provide apparatus o f the 5 character set forth capable of wide variation in the setting thereof.

A more specific object of my invention is to provide a speed governor which will govern within the same percentage of regulation 10y at any one of a number of widely varied speed settings.

Satisfactory governing devices have been developed for governing prime movers at a given speed. Considerable difficulty has been experienced, however, in designing governors for widely varying speeds. This difliculty is due to the fact that the variations in governing force are much greater at higher speeds than at lower speeds, whereas the spring which opposes the governin force 1s capable of roviding but one sca e, which may be suita le for one speed but unsuitable for other speeds.

In accordance with my invention, I provide a regulating mechanism including pressureresponsive elements subjected to the variable fluid pressure in accordance with the speed the mechanism is to regulate, which, in the case of a speed governor, varies as a function of the speed, usually as the square of the speed. I also provide means for varying the area of surface of the pressure-responsive element on which the variable fluid pressure is effective to bias said element. In this way, the same total governing force may be obtained for various iuid pressures corresponding to various speeds, and the same governing action may therefore be obtained at widely varying speeds.

The above and other objects are effected by my invention, as will be apparent from the following description and claims, taken in connection with the accompanying drawings and forming a part of this application,

in'which:

Flg. 1 1s a side elevatlon of a prime mover l having a speed. governor in accordance with my invention; and,

Fig. 2 is a sectional view of the speed governor.

Referring now to the drawing, more in detail, I show a steam turbine 10 having a Steam supply conduit 11 and a dischargeV conduit 12. n admission valve 13 is inter osed in the conduit 11 to regulate the admlssion of motive {iuid to the turbine. The admission valve 13 is controlled and operated by `a. governor 14. The governor 14, in turn, is controlled by fluid pressure developed by a pump 15 driven directly by the rotor shaft 16 of the turbine. The fluid pressure is conveyed to the governor through a conduit 17.

Referring now to Fig. 2, the governor 14 includes a cylinder structure 18, which is bored on the interior thereof to form cylinder walls 19, 20, 21 and 22, of progressively greater diameter. Disposed within the cylinder structure 18 is a piston member 23, which includes piston portions 24, 25, 26 and `27, which fit within the cylindrical walls 19 to 22, respectively.

The piston member 23 is connected to the valve 13 by means of a rod 28, by means of which it controls the valve. The piston member is biased upwardly b a com ression spring 29, the upper end ofywhi piston member and the lower end of which abuts a spring-holdin member 30. Suitable means are provided or moving the springholding member 30 vertically to vary the spring setting. In the present embodiment, this means includes a tubular member 31, which is screw-threaded within the springholding member 30 and which carries abevel Y gear 32, and a stub shaft 33 carrying a pinion 34 meshing with the bevel gear 32. A hand Wheel 35 is secured on the shaft 33 for rotating the same.

As will be noted from the drawing, the cylinder structure 18 is formed with end wall portions. for the upper ends of the cylindrical walls 19 to 22, whereby separate chambers 36 to 39 are formed by the cylinder walls 19 to 22 and the piston portions 24 to 27, respectively.

The piston portion 24 is sub'ected at all times to the fluid pressure devel pump 15, which is transmitted to the chamber 36 by the conduit 17 The fluid pressure provided by the pump 15 is also conveyed through a branch of the conduit 17 t0 a pasoped by the sage 40, and the chambers 37 to 39 communicate with the passage 40 b means of passages 41 to 43, respectively. alves 44 to 46 are interposed in the passages 41 to 43, respectively, whereby the variable fluid pressure may be admitted'to any one of the c ambers 37 to 39 or maybe shut off therefrom. Each ofthe valves is provided with a handle 47 for operating the same.

The valve 44 is shown in elevation in open position, the valve 45 is shown in section in open position,and the valve 46 is shown in section in closed position. Each of these valves is formed with a recess 48 communicatin with a drain passage 49 disposed in back o the plane in which the section -is taken. When a. valve is in closed position as shown by valve 46, fluid in the chamber communicating therewith may be discharged to the drain and atmospheric pressure is maintained in such chamber.

The operation of the above described apparatus 1s as follows: l

To operate the turbine at the highest speed setting provided by variation in piston lsurface, each of the valves 44 to 46 is moved to closed position. The variable fluid pressure is now effective only on the piston portion 24. In view of the fact that the pressure is effective on only a comparatively small area, the turbine must attain a relatively high speed in order that the variable fluid pressure may oppose the force of the spring 29. The governor operates in the manner of a fluid pressure governor, as is well known, as follows:

Upon increase in speed the increased fluid pressure provides increased compression of the spring 29 and downward movement 4of the plston member 23 to effect closing move-4 ment of the valve 13. Upon decrease in speed, the compression of the spring 29 isdecreased and the piston member 23 moves upwardly to move the valve 13 in opening 4direction.

Assuming now that it is desired to operate the turbine at the next highest speed setting provided by the variable piston area construction, the valve 44 is moved to open position, whereupon the variable fluid pressure is admittedto the chamber 37 and is effective on the upwardly facing surface o the piston portion 25. The area or surface of the piston member 23 on which the variable fluid pressure is effective to bias the piston member downwardly, is now increased. The downward force of the fluid pressure on the piston member is now considerably greater and moves the admission valve in closing direction. The speed ofthe turbine now decreases, with consequent decrease in fluid pressure, until the force exerted by the variable fluid pressure is approximately equal to the force which was previously exerted by the variable fiuid pressure on the piston portion 24 alone. The governor now governs the speed.

To govern at the next higher speed setting, the valve 45 is moved to open position and the variable fluid pressure admitted to the chamber 38 to bias the piston portion 26 also. The governor again operates in the same manner but at a still lower speed setting.

To obtain the lowest speed setting, the

turbine in the saine manner but at the lower lvalve 46 is opened in addition to the valves It is apparent that the same variation inv total governing force is required to move the piston member through its travel at all of the various speed settings, inasmuch as the position of the piston member 23 is determined by the deflection of the spring 29. As the va,

riable fluid pressure is proportional to the total governing force, at any one speed setting, the percentage of variation in speed is substantially thesame for all speed settings.

It will be apparent that variation in effective piston area permits of variation in speed setting only in steps. In order to vary the speed setting between the steps provided by vthe variable piston area construction, the setting of the spring 29 may be varied. To do this, the hand wheel 35, is rotated, which rotates the sleeve 31 to raise or lower the spring-holding member 30. This form of adjustment is well known in the art and is suitable for providing gradual change of speed setting within comparatively narrow limits. It may be used to provide change in speed setting from one to the next of the steps provided b the variable piston area arrangement. 'le a change 1n the spring setting changes the percentage of regulation somewhat, this is not ob'ectionable as the extent of variation in Spee setting by this means is limited. The wide changes in speed setting, for which the spring setting adjustment would interpose objectionable chan es in governing characteristics, are provided y the variable piston area which does not effect any change in governing characteristic.

It is apparent that numerous refinements in the details of construction may be embodied in the governor, these being omitted from the drawing for the sake of slmplicity.

From the above description, it will be seen that I'have provided a simple arrangement for providing substantially the same governing action at speeds which may widely vary.

While I have shown my invention in but one form, it will be obvious to those `skilled in the art that it is not so limited, but is i 1 speed of a prime mover within the sameper- :saam 3 centage of speed variation at a` lurality of speed settings, the combination o means pro-v viding a liuid ressure varying as a function` of the speed o the prime mover',v ressure-re- 15 s onsive means su jected to said variable uid pressure andcontrolling the admission of'motive iuid to the priine mover, a spring act ou the pressure-responsive means in opposition to the fluid ressure, and means for Si! varying the area of e surface of the Apressure-res onsive means subjected tosaid variable' fluid pressure. 4-

2. The combination with a'prime mover, of a fluid preure speed govermng mechanism '25 for governing the speed of the prime'inover within the same percentage of speed variation at a plurality of speed settings comprising means providing a fluid pressure varying-as v the square of the s of the rime'mover,

3f means including an controlled y a pressure .responsive element subjected tosuch variable Huid pressure for controlling theadmi'ssion 0f motive fluid to the prime mover, a sprin biasing the pressure-responsive element in op -3'5 position to said iuid pressure, and means for.

varying the area of surface of the pressure-responsive element on which the 'fluid pressure is eiective, to bias said element.-

3; The combination with a prime mover, of

l 10 lluid ressure speed govermng mechamsm there or comprising a cylinder structure having interior cylinder walls of dierent diameters, a piston member having' piston portions fitting said cylinder wall and'formin 4i separate chambers therewith, means provi ing a Huid pressure varying as the square of thespeed o the prime mover, means for ad mitting said variable duid pressure to said chambers to bias said piston portions, valve W means for admittingxor shutting o said pres# sure to one of said c embers, a spring biasin l the piston member in opposition to the dui pressure, and means controlled by said piston i member for regulating the admission of mo- A '65- tive luidto the prime mover.` j

- In testimony whereof, I have sub scribed'my name 18th. day of October,l

Images