US2635639A - Hydraulic regulator with stabilizing device - Google Patents

Description

April 21, 1953 M. A. EGGENBERGER 2,635,639

HYDRAULIC REGULATOR WITH STABILIZAING DEVICE Filed 001). 17, 1951 Inventor Mar-Kus A. Efggenbergev;

` y His Attorney.

Patented Apr. 21, 1953 typ 35 man meer;

I drau-l: liquid, such als a sijcegble petroleumgqil,

housing Illa which may conveniently have end closure members IUb, Ic. Within the housing is a second abutment disk member 22 which iioats, free of frictional contact with housing Ill, between two opposed coil springs 23, 24. The lower surface of disk 22 is sealed to a flexible bellows 25 which defines a second expansible chamber 26, bellows 25 having its lower end sealed to the lower end closure Ib.

For indicating the position of disk 22, a rod 23.

secured to disk 22 may project through the upper end closure Illc, dening a generous annular clearance space 21 therewith. As will be apparent in the drawing, conduit 20 freely communicates liquid from annular chamber I1 to chamber 26 in the stabilizer Ill, while conduit 2| communicates liquid to the space 28 above disk 22 and surrounding bellows 25. The space 28 serves as a storage reservoir for liquid displaced from chamber II, and also serves to keep the connecting conduits full of liquid at all times. To this end, the conduit 2l is connected to housing Illa at a location below the lowest normal level of oil in space 28. It remains to be noted that conduit; 2I includes a throttling valve 2Ia, or equivalent flow restricting device, for a purpose indicated by the method of operation described hereinafter.

To appreciate the operation of stabilizer I0, assume rst that the throttling valve 2 Ia is wide open. If now the steam pressure communicated to chamber I2 by conduit I3 should suddenly increase, the pressure responsive disk I5 will move upwardly against the downward force of spring 4a, substantially unaffected by the liquid in chamber I1, which liquid is merely displaced through conduit I9, 2I to the generously proportioned reservoir space 28 above disk 22 and around bellows 25. In this connection, it should be noted that chamber 28 is in free communication with the atmosphere by way of the clearance space 21, and with the space surrounding bellows 25 by way of the generous clearance space 22h defined between disk 22 and housing wall Illa. Thus, except for a comparatively small amount vof hydraulic damping eifected by the flow of liquid from chamber I 1 to chamber 23, the operation of the servo-mechanism I will be in the manner of the prior art devices of this type. This means that the inherent degree of regulation will be determined by the mechanical characteristics of the spring 4a. For instance, this spring may be so selected that the servomechanism I will control the shaft sealing steam pressure with a change of perhaps 1 pound per square inch as the rate of steam flow changes from vmaximum to minimum.

This degree of regulation may be insufcient t insure stability of the system; therefore, the stabilizer l0 is brought into action. To this end, the throttling valve 2| a is closed partially. If now a sudden increase in the steam pressure occurs, any tendency for disk I5 to move upwardly is resisted, by liquid pressure produced in chamber I1, resulting from the flow of liquid from chamber I5 through conduit I9, 2B to the expansible chamber 26, which moves disk 22 upwardly against the force of spring 23. Conversely a sudden decreaseV of pressure in chamber I2 will cause liquid to be drawn from chamber 26 crease the degree of regulation introduced into the operation of servo-mechanism I. For instance, as compared with a normal regulation of about 1 pound, when valve 2Ia is wide open or when the pressure changes occur slowly, the lnstantaneous degree of regulation effected when valve 2Ia is partly closed maybe 10 pounds per square inch or more. The magnitude of this instantaneous regulation is determined by proper selection of the springs 23, 24, just as the normal regulation of the system is determined by the mechanical characteristics of spring 4a.

The eiTect of varying the resistance to iiow through conduit 2| by changing the degree of opening of valve 2Ia, is to alter the length of time required for the regulation of the system to change from the high instantaneous value to the lower steady state value. With this valve wide open, the regulation quickly settles down to the steady state value. With the valve completely closed, it takes an infinite length of time.

In other words, the stabilizer I0 effects its stabilizing function by providing an instantaneous degree of regulation, in the event of a. sudden change in the condition being controlled, which is many times greater than the steady state regulation which takes place with more gradual changes in the condition. Specifically, the stabilizer may be designed and adjusted to provide an instantaneous degree of regulation on the order of 10 pounds in the event of sudden large changes in steam pressure, the degree of regulation being gradually reduced to a normal value on the order of l pound after a time interval determined by the adjustment of valve 2 Ia.

It will be seen that this stabilizing effect is produced without interference from any mechanical friction effects, since the movable disks I5, 22 and the rods 4, 23 have no frictional engagement with the associated housing portions. Thus the invention provides a very simple, yei-l readily adaptable means for stabilizinga hydraulic servo-mechanism without the interference of mechanical friction eiects.

It will be understood that, while the invention has been described as applied to a steam regulator for the shaft seal of a turbine, it may be applicable to many other types of servomechanisms where analogous problems are encountered. It is also to be noted that the specic mechanical details disclosed herein are intended to be only in the nature of a diagrammatic representation of the mechanical components required to practice the invention; and it Will be obvious to those skilled in the art that i the mechanical parts may take many alternate so as to Vmove disk 22 downwardly against the forms. It is, of course, intended to cover by the appended claims all such modifications as fall within the true spirit and scope of the invention.

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

l. In a servo-mechanism, the combination of a signal output member adapted to be positioned linearly by a signal input force, a first disk member secured to the o-utput member and walls dening therewith a rst expansible chamberand a hydraulic stabilizer comprising walls defining a second chamber vented to the atmosphere and forming a reservoir partly filled with liquid, a second disk member disposed in the second chamber, first and second spring means disposed in the second chamber at opposite sides of said second disk to establish -a neutral position therefor, walls dening a second expansible chamber connected to one side of the second disk; rst conduit means communicating liquid freely between the interior of the rst and second expansible chambers, and second conduit means communicating with the first expansible chamber and c-onnected to the second stabilizer chamber -at a location below the lowest normal level of the liquid therein, and flow restricting means in said second conduit, whereby movement of the signal output member causes displacement of liquid between the rst expansible chamber and the stabilizer, the iiow through said first and second conduits being diflerent by reason of the flow restriction in the second conduit se that sudden movement of the output member results in movement of the second disk member lagainst the bias of one stabilizing spring to create a liquid pressure in the irst expansible chamber tending to resist such movement of the output member.

2. In a servo-mechanism, the combination of a signal output member adapted to be positioned by a signal input force, a first disk member connected to the output member and Walls defining therewith a first expansible chamber, and a. hydraulic stabilizer comprising walls defining a second chamber vented to the atmosphere and forming a reservoir partly filled with liquid, a second disk member disposed in said second chamber, first and second opposed spring means disposed in said second chamber and acting on the second disk to establish a neutral position therefor, walls i defining a second expansible chamber adapted to exert force on one side of the second disk, conduit means communicating liquid between said first and second expansible chambers @and said reservoir, said conduit means communicating with the reservoir at a location below the lowest normal liquid level therein and having means restricting the ow of liquid to the reservoir, whereby movement of the signal output member effects free interchange of liquid between the first and second expansible chambers and past said flow restriction to the reservoir so that sudden movement of the output member effects movement of the second disk mem-ber against the bias of said spring means to create a liquid pressure in the first expansible chamber tending to resist such movement of the output member.

3. In a servo-mechanism, the combination of an output member adapted to be positioned by a signal input force, a rst abutment member connected to exert a f-'orce on the output member and walls defining therewith a iirsty expansible chamber, and hydraulic stabilizer means comprising walls de-ning a second chamber vented to the atmosphere and forming a reservoir partly filled with liquid, a second abutment member disposed in the second chamber with iirst and second opposed spring means acting on said second member to establish Ia neutral position therefor, walls defining a second expansible chamber connected to exert force on said second member, conduit means communicating liquid between said rst and second expansible chambers with a branch to said reservoir, said branch conduit communicating with the reservoir at a location below the lowest normal liquid level therein and having means restricting the liow of liquid to and from the reservoir, whereby movement of the output member effects free interchange of liquid between the first and second expansible chambers and limited iiow past said flow restriction to the reservo-ir so that sudden movement of the output member causes the second abutment member to -move against the bias of the op'- posed spring means to create a liquid pressure in the rst expansible chamber tending to resist such movement of the output member.

MARKUS A. EGGENBERGER.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 1,063,547 Kieser June 3, 1913 1,446,439 Lieberman Feb. 20, 1923 2,077,384 Dettenborn Apr. 20, 1937 2,113,416 Warren Apr. 5. 1938 2,400,048 Jones May 7, 1946 2,469,038 Winkler May 3, 1949 2,554,659 Brannon May 29, 1951

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