US2244131A - Combination low water cutoff and pressure control - Google Patents

Description

June 3, 1941. R N NORSTRAND 2,244,131

QOMBINATION LOW WATER CU'IOFF AND PRESSURE CONTROL Filed March 28, 1939 o /7 415 o /a J 40 10 Z0 j 2y x M r M.

.1 III III A 'ens' a K a? I J INVENTOR 4m Z VAN A msmw Patented June 3, 1941 UNITED STATES PATENT OFFICE COMBINATION LOW WATER CUTOFF AND PRESSURE CONTROL 8 Claims.

This invention relates to boiler controls, and in its preferred embodiment relates to combined water level and pressure controlled devices for cutting off the operation of power-actuated devices such as oil burners, forced draft blowers, and the like.

One object of the invention is to provide a combined low water and high pressure cut-off in which the same switch actuating mechanism is used for both operations. A further object is to provide a boiler control device of this general type in which the float and pressure mechanisms are independent of the angular position in which the carrying frame is attached to the boiler, and in which the control mechanism can be adjusted into its correct angular position after the device is in position on the boiler. A further object is to provide an improved form of mechanism for preventing false indications of the device by reason of surges in the boiler, such mechanism being free from danger of becoming clogged due to the formation of deposits from the boiler water. A further object is to provide a device of this general character having great simplicity of construction. Additional objects will appear from the following description and claims.

Referring to the drawing,

Fig. 1 is a central longitudinal section through the device, the parts being shown in normal or "on position;

Fig. 2 is a similar partial view showing the parts in off position;

Fig. 3 is a section on line 3-3 of Fig. 1;

Fig. 4 is a detail of the control switch, looking from the left in Fig. 1;

Fig. 5 is a similar detail, but showing the parts in the "off" position;

Fig. 6 is a section on line 6-6 of Fig. 1; and

Fig. 7 is a section on line 11 of Fig. 6.

The device is supported by a body portion or plug I0, having a screw threaded portion ll adapted to be screwed into a hole in the side of a boiler, a nut l2 by which it can be rotated, and a chamber I3. A sleeve I4 is held in a central aperture in the plug, as by a press fit, and has a hole l5 through its center flaring outwardly in a direction external to the boiler. The inner end of this hole is contracted at I6 to furnish sliding and tilting support for a rod IT. For this purpose the edges of the contraction l6 are preferably rounded as shown. The sleeve M has a flange l8 to which is secured one end of a corrugated metal bellows IS, the other end of which is secured to a disk 20 fastened in any suitable way to the float 2!. The bellows serves to furnish a flexible connection between the float and the sleeve l4, whereby the float may move either up and down, or toward and away from the sleeve, without permitting leakage between them. The bellows also serves as a pressure control means as will be described.

Rotatably positioned upon the outer end of the sleeve 14 is a control support 25 having a set screw 26 to permit it to be secured in any desired angular position. Upon a pivot 21 carried by this support is an arm 28 to which a mercury switch 29 of a usual type is held by a clamp 30. The rod 57 passes freely through a hole in the arm, so that if the rod tilted from the position of Fig. l to that of Fig. 2 the arm will be rocked sufliciently to shift the switch from the "on to the oil position. An insulating strip 3I' is supported on lugs 32 on the support 25, and carries binding posts 33 by which the mercury switch may be connected to the device to be controlled.

It can readily be seen that, with no more mech anism than that described, the rise and fall of the float in accordance with the level of the water will cause the rod to tilt in its bearing l6 and rock the switch-carrying arm 28. Additional mechanism is, however, necessary to cause the switch to be rocked by an increase in pressure in the boiler, which causes the bellows to be contracted. To convert the longitudinal movement of the rod thus produced into a rocking motion, a linkage is produced which also has the effect of changing the motion of the rod when controlled by water level without, however, varying its effectiveness. The motion of the rod is identical whether the operating force is the sinking of the float or the contraction of the bellows.

To accomplish this result a curved link 35 is pivoted at 36 to a lug on the support 25, and bends over the end of the sleeve M to engage pintles 38 on opposite sides of a sleeve 39 loose on the rod I3. The sleeve 39 can be held in ad justed position on the rod by opposed pairs of lock nuts 40. The operation of this linkage may be most clearly seen if a compressive force be imagined to be exerted on the right-hand end of the bellows. This causes a sliding of the rod ll to the left, but the linkage requires that. any such motion be accompanied by a tilting of the rod to permit it to follow the curved path of the end of the link. (The link, of course, acts as if it extended straight from the pivot 38 to the pivot 36, the former pivot always swinging in an are about the latter.) The rod pivots about the point 16 as always, causing the float to be depressed and elevating the arm 28. Lowering the float in the water requires force, and the float itself thus acts as a resistance against the contraction of the bellows, making the use of springs or of high resilient material for the bellows necessary. In fact, the response to pressure increase can be to some extent controlled by Varying the shape of the float. It is desirable for purposes of control, however, to have the bellows made of resilient material so that an initial bias can be given by the lock nuts it) and the point at which the switch is tripped thus varied. The lock nuts thus serve as a pressure control, together with the ability to rotate the support 25 slightly to change the initial setting of the switch.

When the device is responding to low water the rod goes through exactly the same motion, pivoting still at the point 16. The natural motion is in this case one of tilting, while the motion enforced by the link 35 is one of sliding. But little resistance to such sliding is interposed by the bellows, which is always under some compression due to the excess of pressure inside the boiler. The point at which low water cut-01f is achieved is determined by the position of the device in. the boiler, and is not critical.

It should be particularly noted that the support 25 can be rotated into the desired angular position after the plug l 0 has been screwed home into the hole provided in the boiler wall. This makes it possible to rely upon tapering pipe threads to produce a tight fit between the plug and the boiler instead of requiring packing and accurately turned flanges. The saving of time in installation is very marked. The lock nuts M! can also be adjusted after the device is in place,

making it possible to change or adjust the point at which high pressure cut-off occurs.

It is desirable to protect the float from the oscillations produced by rapid surges within the boiler. For this purpose the plug I0 is provided with a cylinder 4! enclosing the float. The end of this cylinder is braced as by cross members 42, to the center of which is loosely pivoted at 43 a disk 44. When surges occur the disk swings on its loose pivot and prevents the effect of the surges being felt to their full extent within the cylinder. At the same time the slight swinging movement of the disk opens and closes the circumferential aperture between it and the cylinder, and keeps this aperture from becoming plugged due to accumulations of material deposited from the boiler water.

It will be understood that while the device has been described as extending within the boiler it could equally well be mounted upon the wall of a chamber connected to the boiler so that the conditions to be controlled are equivalent within the chamber and within the boiler. The term within the boiler" is, therefore, used for brevity as covering both situations.

I claim:

1. A combined low water and high pressure cut-off comprising a support secured to the wall of a boiler, a rod slidably and pivotally supported in said support, a bellows surrounding the rod and secured thereto so as to make a flexible fluid-tight seal between it and the support, a float carried by the rod, means constraining the rod for simultaneous sliding and tilting movement, a switch, means actuated by one of said movements of the rod for actuating the switch, and a support for said switch and for said lastnamed means permitting their rotative adjustment with respect to the rod after the firstnamed support has been secured to the wall of a boiler.

2. A combined low water and high pressure cut-off comprising a support secured to the wall of a boiler, a rod slidably and pivotally supported in said support, a bellows surrounding the rod and secured thereto so as to make a flexible fluid-tight seal between it and the support, a float carried by the rod, a link having one end pivoted to the rod and its other end stationarily pivoted to the support on the outside of the boiler wall whereby sliding and tilting of the rod must occur simultaneously, a switch, and means actuated by one of said movements of the rod for actuating the switch.

3. A combined low water and high pressure cut-off comprising a support secured to the wall of a boiler, a rod slidably and pivotally supported in said support, a bellows surrounding the rod and secured thereto so as to make a flexible fluid-tight seal between it and the support, a float carried by the rod, a second support adjustable on said first support, a link having one end pivoted to the rod and its other end stationarily pivoted to said second support whereby sliding and tilting of the rod must occur simultaneously, a switch secured to the second support, and means actuated by one of said movements of the rod for actuating the switch, said second support for said switch and for the stationarily pivoted end of the link permitting their rotative adjustment with respect to the rod after the first-named support has been secured to the wall of a boiler.

4. A switch actuating device controlled by conditions within a boiler comprising a float, switch means controlled thereby, a cylinder surrounding the float, and a disk pivoted to close the end of the cylinder loosely to permit water to enter and leave the cylinder by tilting the disk.

5. In a switch actuated float control mechanism of the class described, a cylinder surrounding the float, said cylinder being affixed at one end to the switch means and having at the other end means for insuring a quiet flow of liquid in and out of said cylinder, said means consisting of members aflixed to the wall of the cylinder at the open end thereof and extending across said end, and a disk spaced from the end of the cylinder so that liquid may pass through the cir cumferential aperture between said disk and the cylinder.

6. In a switch actuated float control mechanism of the class described, a cylinder surrounding the float, said cylinder being aflixed at one end to the switch means and having at the other end means to permit a quiet flow in and out of the cylinder, said means consisting of members affixed across the open end of said cylinder, a screw fixed in the center of the intersection of said members, and a disk loosely pivoted on said screw and covering the end of the cylinder, said disk being adapted to flap back and forth on the pivot, thereby preventing any surges due to turbulent forces outside the cylinder from being transmitted inside said cylinder, said action of the disk also preventing accretion of foreign matter in the circumferential aperture between the disk and cylinder.

7. A switch actuating device controlled by conditions Within a boiler, comprising a float, switch means controlled thereby, a cylinder surrounding the float, cross members aflixed to and extending across the open end of the cylinder, and a disk pivoted on said cross members to open and close the end of the cylinder loosely by tilting back and forth, all for the purpose described.

8. A combined low water and high pressure cut-off comprising a support secured to the wall of a boiler, a rod slidably and pivotally supported in said support, a bellows surrounding the rod and secured thereto so as to make a flexible fluid-tight seal between it and the support, a float carried by the rod, a second support adjustable on said first support, a link having one end pivoted to the rod and its other end stationarily pivoted to said second support whereby sliding and tilting of the rod must occur simultaneously, a switch secured to the second support, means actuated by one of said movements of the rod for actuating the switch, said second support for said switch and for the stationarily pivoted end of the link permitting their rotative adjustment with respect to the rod after the firstnamed support has been secured to the wall of the boiler, a cylinder attached to said firstnamed support and surrounding the float, cross members affixed to the wall of the cylinder and extending across the open end thereof, and a disk pivoted on said cross members, said disk being adapted to tilt against the end of the cylinder to prevent a turbulent condition within the boiler from affecting the float inside said cylinder.

RALPH E. VAN NORSTRAND.

CERTIFICATE OF CORRECTION. Patent No. 2,2.M 151. June 5, 191a. RALPH E. VAN NORSTRAND.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, first column, line 14-5, for the word "necessary" read unnecessary- ;;and that the said Letters Patent should be read with this correction therein at the same may conform to the record of the case in the Patent Office Signed and sealed this 8th day of July, A. D. 19141 Henry Van Arsdale, (Seal) Acting Commissioner of Patents.

CERTIFICATE OF CORRECTION. Patent No. 2,2hl 151. June 5, 19m.

Y R LPH E. VAN NORSIRAND.

It is hereby certified that error appears in the printed specificatioil of the above numbered patent requiring correction as follov'x rs: Page 2, first 0011111111, l L-5, or the word "necessary" read --unnecessaryar d that the said Letters Patent should be read with this correction therein at the same may conform to the record of the case in the Patent Office.

Signed and sealed this 8th day of July, A. D. 1914.1

Henry Van Arsdale, (Seal) Actihg Commissioner of Patents,

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