US1831072A - Pressure responsive control device - Google Patents

Description

Nov. 10, 1931. H, 3, LEE 1,831,072

PRESSURE RESPONSIVE CONTROL DEVICE Filed July 25, 1928 2 Sheets-Sheet 1 Nov. 10, 1931. H. B. LEE

PRESSURE RESPONSIVE CONTROL DEVICE 2 Sheets-Sheet 2 Filed July 25, 1928 Patented Nov. 10, 1931 UNITED STATES- PATENT OFFICE HENRY B. LEE, OF NEW LONDON, CONNECTICUT, ASSIGNOR TO LEE ENGINEERING, ZEN-- CORPORATED, OF NEW LONDON, CONNECTICUT, A CORPORATION OF CONNECTICUT PRESSURE RESPONSIVE CONTROL DEVICE Application filed July 25,

' class described, constructed with particular reference to extreme sensitiveness to slight pressure variations, and to minimizing overriding or so-called hunting tendencies.

With this object in view my invention consists in a pressure-responsive control-device having certain details of construction and combinations of parts as will be hereinafter described and particularly recited in the claims. i

In the accompanying drawings I have schematically shown one form of my improvedcontrol-device coupled and arranged to control the amount of air sup lied to the combustion-chamber of a boiler 1n conform ity with the rise and fall of the steam-pres sure in the said boiler, though it will be obvious that my invention is also adapted for use in many other situations, too numerous to' mention, where a pressure responsive control-mechanism is required.

In the accompanying drawings: Fig. 1 is a view in vertical central section through a pressure-responsive control-device constructed in accordance with my invention, together with a steam-boiler, blower and steam-turbine which are schematically shown, the parts of the control device being shown in the positionsdue to them when the rate of combustion beneath the boiler is sufficient to maintain a predetermined pressure therein;

Fig. 2 is a view corresponding to Fig. 1 but showing the parts in the positions due to them immediately upon a decrease in pressure within the boiler; and

Fig. 3 is an enlarged-scale view in transverse section taken on the line 33 of Fig. 1.

In the embodiment of my invention herein chosen for illustration, I employ a counterbalanced pressure-responsive control-unit enclosed within a casing which consists of a 1928. Serial N01 295,183.

cylindrical cup-shaped body-member 10, a cylindrical spacing-ring 11 and a shallow in- .verted cup-shaped head 12. The body-member is secured to the'inner face of a rectangular enclosing-box 13 by means of screws 14,

and has its upper end flanged to receive between it and the lower edge of the spacingring -11 a guide-diaphragm 15 which is clamped in place by screws 16.

Between the upper face of the spacingring 11 and the lower face of the head 12 I clamp by means of screws 17, a pressurediaphragm 18, which latter forms the lower wallof a pressure-chamber 19, located within the head 12 and connected by means of a pipe 20 to a steam service-pipe 21 leading from a steam-boiler 22.

Extending between the 'central portions of the diaphragms 15 and 18 is a spool-like diaphragm coupling-member 23 having its respective opposite ends formed with threaded stems 24 respectively passing through the center of the said dia hragms and provided with nuts 25, each 0 which latter engages a clamping-plate 26 serving to pinch the central portion of the diaphragm between the adjacent end of the coupling-member 23 and the said clamping-plates, as clearly socket 30 receiving the conical upper end of an adjusting-screw 31 threaded into a boss 32 invthe lower end of the body-member 10 and provided at its extreme lower end with a. hand-wheel 33 by means of which the tension of the said balancing-spring 27 may be adjusted as required to balance the pressure within the chamber 19.

The diaphragm coupling-member 23 before mentioned is formed with an annular groove 34, the upper wall of which is engaged by the rounded inner end 35 of a controllever 36 mounted upon a pin 37 carried by a short arm 38 offsetting from the spacer 1 of the casing.

contour of the casing 42 is contracted to form a throat 46 with which the periphery of the gate 41 is adapted to coact to control the flow of water from the chamber 43. Similarly, between the chamber 44 and the chamber 45 the casing is contracted to form a throat 47 with which the periphery of the gate 41 is also adapted to coact to control the escape of water outward into the chamber and thence outward through a drainpipe 48 connected thereto.

The chamber 43 has water supplied to it through a water-supply pipe 49 one branch of which also leads into and servesthe upper end of a hydraulic cylinder 50 forming part of a hydraulic operating-unit and mounted by'screws 51 within the box 13 which houses the pilot-valve just described as well as the control-unit already referred to. The chamber 44 of the pilot-valve is connected by a pipe 52 to the lower end of the cylinder 50 which is closed by a plate 53.

For the urpose of amplifying both the stroke and orce of the control-unit in order to enable the same to indirectly operate a steam-valve 54 and thus control the steampressure within the boiler 22 through the mediary of the air' supply thereto, as will hereinafter appear, I employ a' hydraulic operating-unit consisting of'the cylinder 50 a ready referred to and a piston 55 located therein and providedwit'h a hollow pistonrod 56 carrymg-at its ltilpper end a head 57 i having a horizontallyetting arm 58.

At diametrically-opposite points the said head 57 has upstanding from ita pair of operating-rods 59 reciprocating in bearingbosses 60 in the top wall of the enclosing-box 13 and carrying in turn at their upper ends a cross-head 61 to one,side of which is pivotally connected a link 62 pivoted in turn at its opposite end to the arm 63 of the steamvalve 54 already referred to. a

The steam-valve 54 just referred to may be of any approved type, and-as shown is interposed in a steam pipe 64 which supplies steam from the main service-pipe 21 to a steam-turbine 65 having driving connections with a blower 66, which latter is adapted to inject air beneath the fire-box and ate of the steam-boiler 22 before referre to, in quantities appropriate to the speed at it is driven by the said turbine 65.

Extending between the outer end of the arm 58 of the piston-rod head 57 aforesaid which.

and the control-lever 36 near its outer end, is a so-called range-spring 67, the function of which will hereinafter appear in connectlon with the description of the operation of my improved device.

In order to yieldingl couple the controllever 36 to the piston-r0 56 with capacity for automatic intermittent release, the said control-lever has pivoted to it about midway of its length, a dash-potplunger 68 extending downward into adash-pot chamber 69 formed in the hollow piston-rod 56 where it is provided with a disk-like plunger-head 70 slightly smaller in diameter than the internal diameter of a series of annular lands 71 formed in the wall of the said chamber 69. The said lands 71 are separated by annular grooves 72 which latter are of sufficiently large diameter to permit the ready flow of oil or other liquid contained in the chamber 69 past the plunger-head 70 when the same is in alignment therewith as shown in Fig. 1 of the drawings.

For the purpose of description it may be supposed that the blower 66 is supplying the exact amount of air required toburn the fuel within the fire-box of the boiler 22 at a rate sufficient to maintain the required steam-pressure within the said boiler and the servicepipe 21.

Under the conditions just described the parts of my improved control-device will be in the positions shown in Fig; 1 of the drawln 's.

if now, owing for instance to the starting up ,of an extraunit of steam-driven equipment, the pressure within the boiler 22 will drop. Immediately, that this occurs the pressure within the chamber 19 of the control-unit will correspondingly fall and permit the balancing-spring 27 thereof to flex the d1aphragms l5 and 18 upward and correspondto flow through the very narrow annular clearance-space between the said land andv periphery of the longer-head 70.

The downward movement of the control lever 36 above described will move the gate 41 of the pilot-valve downward, thereby permitting the water within. the chamber 43 thereof to flow into the lower end of the hydraulic cylinder 73 with more or less rapid- 1ty depending upon the degree to which the said gate 41is moved away from the throat 46.

Now owing to the greater area of the underface of the piston 55 as compared to the area of its upper face, the pressure thus built up beneath it will slowly force it upward with the almost immediate effect of restoring the control-lever 36 "to the position in which it is shown in Fig. 1 and hence of lifting the gate .41 and shutting ofi the flow of water into the lower end of the cylinder 50.

The upward movement of the piston 55 just described effects through the iston-rod 56, rods 59, cross-head 61 and lin 62, a slight additional opening of the valve 54 so that an increased amount of steam is sup liedto the turbine 65 to increase its speed an hence supply a slightly increased amount of air to the fire beneath the boiler 22. The increased rate of combustion occasioned by the ingress of a greater amount of air beneath the fire-box of the boiler will, it follows, cause increased rate of steam production. If this increased steam production proves suflicient to-restore the predetermined pressure within the boiler,

notwithstanding the increased load referred to, the parts will remain in the positions shown in Fig. 1.

If on the other hand the above described increase in the speed of the turbine 65 and blower 66 is not suflicient to increase combus tion to the point required to restore the steampressure, the lever 36 will again swing downward with the effect as before described of causing the pilot-valve to admit more water beneath the piston with the result that the same will move upward again another short distance and further open the valve 54 an additional slight degree. v

This second upward movement of the piston 56 will again occasion the control-lever 36 to be restored to. its horizontal position by the yielding connection afforded by the fluid within the chamber 68, and this stepby-step increase in the speed of the turbine and blower will continue until such time as the rate of combustion beneath the boiler is suflicient to maintain :the steam-pressure therein at the required pressure.

Conversely, should the demands upon the boiler be decreased for any reason, the steampressure therein will rise .above a prede termined standard,- thereby causing the diaphragm coupling-member, together with the diaphragms 15 and 18, to move downward and hence causing the control-lever 36 to swing upward into the position shown by broken lines in Fig. 2, with the effect ofmoving the gate 41 of the pilot-valve upward clear of the throat 47 so as to permit the water beneath the piston 55 in the cylinder 50 to flow outward through the drain-pipe 48 under the urge of the pressure developed upon the upper face of the said piston by the water flowing into theupper end of the said cylinder from the water supplypipe 49.

The piston 55 will thus be forced to descend with the effect of partly closing the valve 54 and decreasing the amount of steam supplied to the turbine 65 so that the speed of the latter, together with that of the blower 66, is slackened and the combustion rate beneath the boiler 22 correspondingly deereased. In this action of my improved control-device also, the plunger-head .co-acts with the lands 71 to yieldingly restore the control-lever 36 and parts connected theregith, to their normal positionsshown in 1 'The cycle just above described will be repeated until such time as the rate of combustion within the boiler 22 has been decreased sufliciently to maintain the pressure therein at the normal predetermined poundage.

67 are commonly employed in connection with devices of the class to which my invention relates, so that the function of the range-spring herein shown is well understood and requires no detailed descri tion other than to say that its strength etermines the range of pressure change withln the boiler, required to cause the piston 56 to.

friction of the said diaphragms of the said spring, which is negliglble'. 7

Furthermore, the pivot 37 of the control- Range-springs similar to the range-springs lever 36 is required to carry but a very slight load so that its sensitiveness is not apprecia- -bly impaired:

By employing the guide-diaphragm 15 and arrang ng the same parallel with the I pressure-diaphragm 18, the diaphragm coupling-member 23 is prevented from canting and compelled to move in a substantially rectilinear path.

Forming the dash-pot chamber 69 w1th1n the interior of the piston 56 enables me not only to greatly reduce the height of the entire device, but also to secure a directness ofaction not hitherto attained. It is to be notedalso that I obtain the differential pressures upon the respective opposite sides of a single piston 55 ratherrthan employing two pistons, one spaced above the other in separate cylinders as has heretofore been the ractice.

T 15 action of the grooves 72 in the wall of the dash-pot chamber 69, alternately with the lands 71, effects an intermittent couplin and release between the lever 36 and the pistonrod 56 so that when the plunger-head is in v sudden release of the coupling action of the fluid jiggles, so to speak, the parts and frees any binding tendency of the various pivots and connections.

I wish to call attention alsoto the simplicity, convenience and directness of the arrangement of parts within the enclosing-box 13. It will be noted that the straight bar like control-lever 36 extends crosswise of the said box so that the three main units of my improved device, namely, the control-unit, the hydraulic operating-unit and the pilot valve-unit, may be all connected thereto in a direct and proper sequence.

The operating-unit and the pilot-valve together constitute what I shall for convenience term an amplifying mechanism for amplifying both the power and stroke of the controlunit, to enable the latter to operate (indirectly) a bulky and resistant device like the steam-valve 54. v

I claim:

1. A pressure-responsive control-device comprising a pressure-responsive controlunit; a hydraulic operating-unit including a cylinder and a hollow combined piston and dash-pot formed interiorly with alternate lands and grooves; a pilot-valve; a controllever pivoted between its ends and connected at one end to the said control-unit and at its opposite end to the said pilot-valve; a dashpot plunger operating at one end within the said combined piston and dash-pot and connected at its opposite end to the central portion of the said control-lever; whereby the said control-unit and the said amplifying mechanism are yieldingly coupled together with capacity for periodic automatic release.

2. In a pressure-responsive control-apparatus, the combination with a pressure-responsive unit actuatable in response to variations in the fluid-pressure such as from a steam-boiler; an operatingdevice for operating a valve or the like; a control-device for the said operating-device and connected to the said pressure-responsive unit for being governed thereby; and a yielding step-bystep dash-pot connection between the said operating-device and the said control-device, including a dash-pot-chamber member and a dash-pot-plunger member, one of which members is provided, upon the surface there of which coacts with the surface of the other member, with-alternating lands and grooves to provide for yieldingly coupling the said operating-device and the said control-device together with capacity for periodic auto- I,

matic release.

3. In a pressure-responsive control-apparatus, the combination with a steam-boiler, a steam-operated prime-mover, a steam-duct leading from the said boiler to the said primemover, and a steam-control valve interposed in the said steam-duct for controlling the supply of steam to the saidprime-mover; of a pressure-responsive unit actuatable in re-' sponse to variatlons 1n the steam-pressure 1n draulic operating-device and operatively connected to both the said hydraulic controlvalve and the said pressure-responsive device; one of the respective coacting surfaces of the said dash-pot plunger and dash-pot chamber being formed with alternate lands and grooves.

In testimony whereof, I have signed this specification.

HENRY B. LEE.

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