US1952265A - Automatic cut-off - Google Patents

Description

March 27, 1934. G ND 1,952,265

AUTOMATIC GUT-OFF Filed Dec. 31, 1929 2 Sheets-Sheet 1 //\/\/'NTOR. GEORGE H. LELAND.

ATTORNEY March 27, 1934. G, H ND 1,952,265

AUTOMATIC CUT-OFF Filed Dec. 51, 1929 2 Shee'is-Sheet 2 Z4 //\/VENTOR. 25 GEORGE H. LELAND.

4 TTORNEY Patented Mar. 27, 1934 PATENT OFFICE AUTOMATIC CUT-OFF George H. Leland, Dayton, Ohio, assignor of onehalf to The Leland Electric Company, a corporation of Ohio Application December 31, 1929, Serial No. 417,683

2 illaims.

This invention relates to an automatic cut-off and is designed primarily for controlling the operation of an apparatus for supplying fluid fuel to burners. In certain apparatus of this kind the fluid fuel, or one of the constituent elements thereof, is delivered to a container, under pressure, by a motor operated pump, the container being connected with the burners. Such an ap paratus is usually supplied with a pressure controlled device for so operating a switch in the motor circuit as to maintain the pressure within the container between certain predetermined limits. It is desirable, however, that means should also be provided for opening the motor switch when the pressure within the container falls to an abnormally low level. For example, should the supply of current to the motor circuit be interrupted and the motor switch closed by the fall of pressure to the normal low limit the motor would, of course, fail to operate and ii a burner was lighted the pressure in the container would continue to fall until it was no longer sufiicient to supply fuel to the burner and the flame of the burner would then be extinguished. If subsequently the supply of current to the motor circuit was restored the motor would immediately begin to operate and to build up pressure in the container, thus causing fuel to be delivered to the burner where it would escape into the atmosphere. Not only would this result in a waste of fuel but it would be liable to cause an accumulation of gas in the room in which the burner was located, which might result in an explosion. In cut-offs of this type as heretofore manufactured it has been customary to provide a separate pressure controlled device for opening the switch when the pressure falls to a predetermined abnormally low level. Such a second controlling device not only increases the cost of 40 the mechanism but it complicates the mechanism and the operation thereof and renders the same more difiicult of maintenance.

One object of the present invention is to provide such a mechanism in which a single controlling deyice, which may be controlled by fluid pressure or otherwise, will operate the cut-off both under normal conditions and under abnormal conditions.

A further object of the invention is to provide such a; mechanism in which a single pressure' controlled device will open the cut-oii at a predetermined high pressure, will close the cutofi at a normally low pressure and will again open the cut-off at an abnormally low pressure.

A further object of the invention is to provide such a mechanism having a single operating member which will actuate the cut-off both under predetermined normal conditions and under predetermined abnormal conditions.

A further object of the invention is to provide such a mechanism having an operating member, the movement of which in one direction will open the cut-oil and the continued movement of which in the other direction will first close the cutoff and then open the same.

A further object of the invention is to provide such a mechanism in which the cut-off will be moved quickly from one position to the other.

Other objects of-the invention will appear as the mechanism is described in detail.

In the accompanying drawings Fig. 1 is a horizontal section taken through the casing ofa mechanism embodying my invention and showing the mechanism in plan; Fig. 2 is a front elevation of such an apparatus with the closure removed and showing the operating mechanism in elevation and partly broken away; Fig. 3 is a sectional detail view showing the operating parts in a position to maintain the cut-off closed; Fig. 4- is a similar view showing the operating parts in the position to which they are moved when the pressure reaches its normal high limit; Fig. 5 is a similar view showing the parts in positions to which they are moved when the pressure reaches an abnormal low limit; Fig. 6 is a detail view of the actuating plate for the cut-off; Fig. '7 is a detail view of the supporting bracket for the actuating plate; Fig. 8 is a circuit diagram; and Fig. 9 is a detail view of the resetting device.

In these drawings I have illustrated one embodiment of my invention and have shown the same in the form of a pressure controlled electrical cut-oiT or switch, but it will be understood that this particular embodiment has been chosen for the purpose of illustration only and that the mechanism may take various forms and may be used in connection with cut-offs of various kinds.

In that embodiment here illustrated the mechanism comprises a supporting structure 10 which is preferably in the form of a casing having a 100 removable front wall or closure 11. The cut-oft is preferably mounted upon the supporting structure and, in the present instance, it is shown in the form of an electrical switch mounted within the casing. Any suitable type of switch may be 105 employed but the one here shown is in the form of a mercury tube 12 mounted for pivotal movement and having within the same two contact members 13 and 14 which are connected by flexible conductors 15 and 16 with terminals 17 and 110 18 which in turn are connected with the circuit 19 of a motor. The motor is not here shown but in a gas apparatus of the type above mentioned it would operate a pump to deliver fluid to the container. The mercury tube is supported by clips 20 secured to and depending from a supporting plate 21 which is pivotally mounted for movement about an axis transverse to the length of the tube and constitutes an actuating device for the cut-off or switch. The tube contains mercury in such quantity that when the tube is in a substantially horizontal position the mercury will engage both the contacts 13 and 14 and close the circuit through the motor. When the actuating plate 21 is moved about its axis to tilt thetube the mercury will move to one end of the tube and out of engagement with one or both of the contacts, thereby interrupting the circuit through the motor. The supporting plate may be pivotally mounted in any suitable manner but in order to reduce the friction as far as possible I have provided the same with knife edged bearings. In the present construction the actuating plate has on the respective sides thereof oppositely facing knife edges, 22 and 23, arranged in axial alinement and seated in V-bearings in the depending arms 24 and 25 of a supporting bracket 26 which, in the present instance, is secured-to the top wall of the casing. The knife edges are held in contact with their bearings by means of a spring which will be hereinafter described.

The actuating plate 21 is moved about its axis to tilt the switch by means of an operating member 27 which, in the present instance, is in the form of an elongated plate or lever pivotally mounted at one end on the end wall of the casing, as shown at 28, and is provided with an opening 29 through which the arms of the bracket 26 extend so that the operating member is arranged directly above the actuating plate. This operating member is of such a character and is so arranged that when it is in an intermediate position, which may be characterized as its normal position, the actuating plate 21 will be in a substantially horizontal position and the switch will be closed. If the operating member is moved upwardly from its normal intermediate position the actuating plate will be moved about its axis and the switch tilted to an open position. If the operating member moves downwardly from its normal intermediate position the actuating memher will be moved about its axis in the same direction to again tilt the switch to its open position. In the present construction the operating member has at one edge thereof a depending flange 30, the outer end portion of which is so shaped as to provide a finger 31 which extends inwardly beneath a lug 32 extending laterally from the actuating plate 21 on the outer side of its axis. An intermediate portion of the flange 30 extends above and is adapted to engage a second lug 33 extending laterally from the actuating plate on the inner side of its axis. The arrangement is such that either the upward or downward movement of the operating member from its normal intermediate position will cause the actuating plate to be tilted to open the switch.

The movement of the operating member is controlled by a controlling device and, in the present instance, this controlling device is controlled by the fluid pressure in the container. As here shown, a stud 34 is secured to and depends from the operating lever 27 at a point spaced a short distance from its axis and this stud has in its lower end a recess 35 to receive the pointed upper end of a plunger 36 which is slidably mounted in a bearing or boss 37 on the bottom wall of the casing. The lower end of the plunger extends through the bottom wall of the casing and into a housing 38 carried by the casing and within which the plunger is connected with a pressure operated member, such as a sylphon 39. The housing 38 is fluid tight and is connected by a pipe 40 with the container so that the fluid pressure within the housing will be the same as that within the container. The pressure within the housing acts on the sylphon in a direction to impart upward movement to the plunger and this movement is resisted by a spring 41 connected with the lever. In the present instance, the spring 41 is coiled about the plunger and has its ends mounted in screw threads carried by the stud 34 and the boss 3'7, the threads on the stud being left hand threads and the threads on the boss being right hand threads, whereby the rotation of the spring will cause the end portions thereof to be moved toward or from each other and the tension of the spring varied.

Interposed between the actuating plate 21 and the operating lever 27 is a spring 42 which has several functions. In the present arrangement, the actuating plate has a finger 43 extending outwardly from the inner end thereof and spaced some distance from the body of the plate. This finger has a bearing point 44 arranged substantially in the vertical plane of the axis of the plate but spaced a short distance below that axis. The operating lever has at its outer end a depending lug 45 in which is mounted an inwardly extending finger 46 having a bearing point and here shown as a screw adjustably mounted in the lug. The spring 42 is a compression spring and is provided at each end with conical seats 4'? to receive the respective bearing points 44 and 46. The spring 42 is normally under pressure and because of the offset position of the arm 43 with relation to the body of the plate 21 the spring tends normally to move the actuating plate about a vertical axis in a direction to cause the knife edges 22 and 23 to be held firmly in contact with their bearings. The bearing point 44 of the arm 43 being slightly below the axis of the actuating plate this spring also tends to move the plate about its transverse axis in a direction to hold the lugs 32 and 33 in engagement with the finger 31 and flange 30 of the operating member, thereby stabilizing the actuating plate and firmly retaining the switch in its closed position so long as the operating member is in its intermediate position. The bearing points 46 of the operating member and 44 of the actuating plate are approximately in a line extending through the axis 28 of the operating member. The point 44 is slightly below this line when the parts are in the intermediate positions shown in Figs. 2 and 3 but it is so nearly in line with the point 46 and the axis 28 that the spring will tend to hold the operating member against movement about said axis.

With the parts in the positions shown in Figs. 2 and 3, the switch is closed and the motor operating and the pressure in the container and in the housing 38 will gradually rise. The resistance of the spring 42 to the movement of the operating member 27 is such that the plunger 36 of the controlling device will be held against movement until the pressure in the housing 38 has reached a predetermined high point, say seven pounds. This high pressure will be sufiicient to overcome 'sure within the container.

the action of the spring 42 and the operating lever will be moved about its axis. As soon as the bearing point 46 of the operatinglever is moved substantially out of line with the point 44 of the actuating plate and the axis 28 of the operating lever the spring 42 will expand to move the lever quickly to the limit of its movement thereby causing the mercury tube to be quickly tilted and the circuit broken, as shown in Fig. 4. As here shown, a lug or pad 48 depending from the top wall of the casing forms a stop to limit the upward movement of the operating lever. As the pressure in the housing 38 falls the spring 41 of the controlling device will exert a downward pull upon the operating lever and this pull is resisted by the spring 42 until the pressure has fallen to a predetermined point, say four pounds, at which time the spring 41 will overcome the spring 42 and the lever will be moved to its intermediate position. The spring 42 acting upon the finger 43 of the actuating plate will cause that plate to move with the operating lever and thus restore the cut-off to its closed position, as shown in Fig. 3. Should the motor fail to operate when the circuit is thus again closed the pressure in the housing 38 will continue to fall until its reaches a predetermined abnormally low point, say two pounds, when the tension of the spring 41 of the controlling device is sufficient to overcome the spring 42 and move the operating lever downwardly, thus carrying the bearing point 46 out of line with the bearing point 44 and the axis 28 and causing the operating lever to be moved quickly to the lower limit of its movement. During this movement the flange 30 will act on the lug 33 of the actuating plate to tilt the. same to the position shown in Fig. 5, thus again opening the circuit. The motor circuit being opened the re-establishing of the current supply to the motor circuit will not cause the operation of the motor and it is necessary that the motor or pump should be operated in some manner to restore the pres- This may be done in various Ways. In the present instance, the operating lever is provided with a finger 49 which ex tends laterally to a point near the front wall 11 of the casing. Pivotally mounted on the inner side of the front wall is a resetting member 51 which has a finger piece 52 extending through a slot 53 in the wall. The resetting member is'so mounted that it will normally move to its lowermost position, as shown in dotted lines in Fig. 9. When the operating lever has moved downwardly from its intermediate position the finger 49 will lie just above the resetting member and when that member is moved about its axis by the finger piece 52 it will engage the finger 49 and lift the operating member to its normal or intermediate position, thus closing the circuit and starting the motor. The upper edge of the resetting member has flat contact with the finger 49 and the thrust of the operating lever will hold the resetting member in its operative position, thus retaining the switchin its closed position and permitting the pressure to build up in the container. When the pressure becomes sufficient to lift the operating lever above its normal position the resetting member will be released and drop to its lowermost position. If desired, the motor may be provided with an auxiliary circuit having a manually operated switchby means of which the circuit can be closed through the motor independently of the circuit 19 and the motor thus caused to operate to build up the pressure in the container,

which would automatically restore the operating member 27 and the other parts to their normal positions. The switch for such an auxiliary circuit should be of such a type that it will automatically open when the pressure thereon is relieved, such as a push button, so as to avoid the possibility of this auxiliary circuit being permitted to remain closed; Such an auxiliary circuit is shown at 50 in the circuit diagram of Fig. 8.

The operation of the device will be readily understood from the foregoing description and it will be apparent that the mechanism there shown may be used, either with or without modification, to operate cut-offs of various kinds and that the movement of the operating member may be controlled in any suitable manner, as by means of a thermostat or voltage controlled solenoid. Thermostats and solenoids of this type are well known and it will be obvious that they could be substituted for the pressure operated device of the application and would constitute the full equivalent thereof.

While I have shown and described one embodiment of my invention I wish it to be understood that I do not desire to be limited to the details thereof as various modifications may occur to a person skilled in the art.

Having now fully described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. In a mechanism for operating a cut-off, an actuating plate connected with said cut-off and having on the respective sides thereof oppositely facing knife edges, open bearings to receive said knife edges, said actuating plate having a finger extending transversely to its axis and having one end arranged substantially in line with but slightly below said axis, a pivoted operating member having a part arranged to engage the upper surface of said actuating plate on one side of its axis and a part to engage the lower surface of said actuating plate on the other side of its axis, said operating member having a depending portion arranged on.that side of said actuating plate remote from the axis of said operating member,

said depending portion having a finger arranged side thereof a finger spaced from the adjacent knife edge and depressed below the axis of said plate, a lever pivotally mounted at one end on said supporting structure, arranged above said plate and having a part to engage the upper surface of said plate on one side of the axis thereof,

and having another part to engage the lower surface of said plate on the other side of the axis thereof, said operating member also having a finger'secured thereto but spaced below the same and arranged substantially in line with the finger of said plate and the axis of said lever, a spring confined between said fingers, and means for imparting movement to said lever.

GEORGE H. LELAND.

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