US1929994A - Automatic motor cut-off and warning signal for stokers - Google Patents

Description

4Otrt. 10, 1933. l F, J, SCHLOTMAN 1,929,994

AUTOMATIC MOTOR CUT-QPF'AND WARNING SIGNAL FOR STOKERS l2 Sheets-Sheet l -Filed Feb. 25, 1931 R. m n m m a DoA W m@ L Ill A o all. ...n/ C 5 J w r @Y h me Oct. 10, 1933; F, 1 SCHLOTMAN 1,929,994

AUTOMATIC MOTOR cUTOFF AND WARNING SIGNAL FOR sTOKERs Filed Feb. 25, 19:51 zsneets-sheet -2 A.. 'l' INVENTON;

Otman ATTORNEY.

Patented Oct. 10, 1933 AUTOMATIC MOTOR CUT-OFF AND WARN- ING SIGNAL FOR STOKERS Frank J. Schlotman, St. Bernard, Ohio, assignor to The Breeding Coal Stoker Corporation, Cincinnati, Ohio, a corporation of Ohio Application February 25, 1931. Serial No. 518,094

Claims.

This invention relates to a combined automatic motor cut-off and warning signal for stoker drives and the object of the invention, generally stated, is to provide a device associated with the driving 5 and driven elements of the stoker which, in the event any foreign matter, contained in the coal, is caught or clogged sufficiently in the feed screw to jam or otherwise interfere with its operation, said device will automatically sever the circuit to the motor for the driving unit and close the circuit of a warning signal, Ithereby instantly notifying thel attendant of the trouble.

At the present time and to the best of my knowledge, when coal containing foreign matter is fed to the stoker, said foreign matter, when reaching the feed screw, is apt to cause the latter to jam and this stoppage of the screw, in turn, throws a breaking strain on the moving .parts of the stoker drive unit unless some means is provided for preventing such a condition. The usual means employed for overcoming this difficulty is to provide a shear pin between the driving and driven elements-that is, a pin that is weaker than the driving parts and which will be sheared off when subjected to excessive strain. The shearing of this pin severs the connection between the driving and driven elements only but does not, however, stop the driving motor or the operation of the forced draft fan; consequently, unless the condition is discovered immediately, the stoker may be severely damaged or the boiler pressure or temperature apt to have a serious drop before the attendant discovers the fact that the coal feed has been stopped.

It is the aim of the present invention to provide means controlled by the shearing pin whereby when said pin is broken, due to any stoppage of the feed screw, said means will be automatically actuated to sever the circuit of uhe driving 40 motor, thus simultaneously discontinuing the operation of the forced draft fan and closing an electrical circuit to a warning signal.

With the above and other objects in view, my in vention consists in the novel features of construction and arrangement of parts hereinafter described and claimed and illustrated in the accompanying drawings.

Referring to the drawings:

Fig. 1 is a side elevational view of a Stoker drive unit having my invention installed thereon, parts appearing in vertical section and the forced draft fan being omitted;

Fig. 2 is an end elevation of the switch control unit;

Fig. 3 is a plan view of the same;

Fig. 4 is an isometric View of the switch box and attaching bracket therefor; A,

Fig. 5 is an end view of the switch control unit cover;

Fig. 6 is a fragmentary isometric view showing end portions of the driving and driven elements of the stoker unit;

Fig. '7 is an isometric detail of the driving element collar; and

Fig. 8-is a diagrammatic view illustrating the electrical wiring.

In the embodiment of my invention as illustrated and which shows a preferred construction, attention is directed to Fig. 1, wherein the driving unit for an underfeed stoker is shown with the invention installed thereon and while a description of this stoker driving unit is necessary in order to explainthe objects and advantages of my improvement, it will be understood, however, that the invention is applicable to stoker drives of ldifferent types and sizes, the only essential requirement being that the driving and driven elements of the unit employ a shear pin, as the invention relies upon a shear pin or its 'equivalent for its successful operation.

' Stoker driving unit.-Referring to the stoker driving unit in detail, 1 designates the casing or housing, the bottom of which is provided with feet 2 adapted to rest upon the concrete base 3, as shown in Fig. 1. Considering the driving element of the unit rst, 4 represents an electric motor, 5 its drive shaft upon which is fixed a worm 6, the latter being in constant mesh with worm gear 7. The forced draft fan (not shown) is driven by the motor drive shaft 5 and is in operation whenever the motor 4 is running. Worm gear 7 is keyed to shaft 8, the shaft 8, in turn, being keyed to pinion 9 and journaled in bearings 10 and 11 carried by the housing 1. Gear 12 is keyed to the hollow driving shaft 13 and is in meshing engagement with pinion 9, as shown, the outer end of said hollow shaft being journaled in bearing 14, which bearing is' also carried by the housing 1. The bearings 10 and 14 are held within the housing 1 by cover plates 15 and 16, respectively, coverplate 15 being bored out to receive the hollow shaft 13 and lubricating plug 17. The outer end of hollow shaft 13 is provided with oppositely disposed notches 18-18, as best seen in Fig. 6, t receive the projections 1.9-19 of driving collar 20. 'I'his The description thus far relates to the parts known as the driving element of the stoker unit-that is when the motor 4 is running the motor drive shaft 5 is set in motion and drives the worm 6, the worm 6, in turn, driving the worm gear 7, which gear drives shaft 8, the shaft 8, in turn, driving the pinion 9, the pinion 9 in turn driving the gear 12, which gear, in turn, drives the hollow shaft 13, said shaft, in turn, driving the collar 20, due to the projections 19--19 of said collar engaging the notches 18-18 of said shaft.

Considering next the driven element of the stoker unit, 23 designates a shaft, one end of which is reduced and received within the hollow driving shaft 13 and terminates in the squared end 24, as clearly illustrated in Fig. 6. This reduced end of shaft 23 is also provided with a centrally disposed hole 25 to receive the shear pin 22, as shown in Fig. 6. When the driving collar 20 is placed upon the reduced end of shaft 23 and slid upon said shaft so that the projections 19-19 of said collar engage the notches 18-18 of the hollow driving shaft 13, the holes 21-21 of said collar will be in alinement with the hole 25 in the reduced end of shaft 23 whereupon the shear pin 22 is inserted Within said holes 21-21 in the collar 20 and hole 25 in shaft 23, thus coupling said collar 20 to said shaft 23 by means of the pin 22 and also xing said collar 20 with the hollow driving shaft 13 by means of the projections 19 and the notches 18, as will be readily apparent by a study of Figs. 6 and 7, respectively. Near one end of shaft 23 is a pinion 26, which pinion is formed as an integral part of said shaft. The outer end 27 of said shaft 23 is journaled within bearing 28, the latter being carried by the housing 1 and retained therein by cover plate 29, as clearly illustrated in Fig. 1. Meshing with the pinion 26 is a gear 30, which gear is xed upon shaft 31, the latter being rotatably journaled within the bearings 32 and 33, respectively. These bearings 32 and 33 are carried by the housing 1, the latter bearing being retained within said housing by cover plate 34. The outer end of shaft 31 is provided with a reduced squared portion 35, which is adapted to be received by the socket 36 in the feed screw 37. Hopper 38, a portion of which is shown in Fig. 1, is suitably attached to the housing 1 and is adapted to supply fuel to the feed screw 37 in the usual manner.

Operation of the Stoker driving unit-With a stoker driving unit, as above described, it will be apparent that the connection between the driving element and the driven element of the unit depends upon the shear pin 22 and, as above stated, should any foreign matter clog the feed screw 37 so as to stop the same, a breaking strain would be put upon the driven element of the unit and as the shear pin 22 is the weakest part of the unit, said pin will be broken or sheared off to prevent damage to the unit, at which time the motor 4, the forced draft fan and the driven element will continue to operate.

At the present time stoker units employing shear pins have no means for notifying the attendant that the feed screw is jammed and stopped and that the motor operating the forced draft fan is running without any fresh fuel being fed by the feed screw 37.

As previously stated, the object of the present invention is to provide such a means-that is, mechanism whereby the motor operating the forced draft fan is shut off when the shear pin is broken, and also to set an alarm into operation to notify the attendant that such a condition exists in the Stoker drive unit.

A preferred embodiment of this means is shown attached to the stoker drive unit in Fig. l and in detailed parts in Figs. 2, 3, 4, 5 and 8, respectively.

Switch control unit-The switch control unit, shown in detail in Figs. 2 and 3, is composed of tubular members 39 and 40, member 39 of which is telescopically received within member 40, as shown in Fig. 3, and one end of member 40 being substantially closed by ears 41 formed as an integral part of member 40 to provide one seat for the expansion spring 42. The other Vend of said spring 42 seats against pin 43, which pin is carried by the tubular member 39 and projects upwardly through slot 44 in the tubular member 40. Said pin, working within said slot, acts as a stop for the outward movement of said tubular member 39 relative to tubular member 40 due to the action of the spring 42. Disc or projection 45 surrounds the tubular member 40 and is suitably xed to the latter in any suitable manner, as, for example, by the ears 46 and rivets 47, as clearly illustrated in Fig. 3. This disc 45 is further provided with an arm 48 bent to lie in a plane parallel to the side of member 40 and having a notch 49 near its end to receive the projecting end of the shear pin 22, as will be presently described. The interior dimension of the tubular member 39 is of a size suitable for receiving the squared end 24 of shaft 23 and is adapted to be held upon said squared end 24 by a locking screw 50. When the tubular member 39 is thus fixed upon the squared end 24 of shaft 23, the tubular member 40 is pushed inwardly towards said shaft 23 so that the expansion spring 42 is collapsed or put under tension, which tension is maintained by the arm 48 embracing the shear pin 22. This is the normal position of the switch control unit and is shown by full lines in Fig. 1.

Switch box and attaching bracket-Referring next to the switch box, designated 5l and shown in Figs. l and 4, this box houses the toggle switch 52 (shown in Fig. 8) and is suspended below the switch control unit by the bracket 53, which bracket is suitably attached to the cover plate 15 before mentioned. The control lever 54 of the toggle switch 52 projects upwardly through a slot 55 in the bracket 53 so as to be in the traveled path of disc 45. This toggle switch 52 is directly connected to the service wires 56 and is adapted to connect said service wires with the conductors 57 and 58 to motor 4, or to connect the service Wires 56 with the conductors 59 and 60 to an alarm, which in the present showing is illustrated as an electric bell 61. 62 represents a transformer inserted within the conductors 59 and 6G. provided with inwardly disposed' anges 64, as shown in Fig. 5, and which are adapted to be slidably received within the grooves 65-65 formed between the switch box 51 and the bracket 53, as clearly illustrated in Fig. 4. When this cover 23 is slid upon the switch box 5l, the switch control unit is entirely enclosed and concealed from view, as shown in Fig. 1.

Operation-In operation, my improved automatic motor cut-off and warning signal for stokers operates in the following manner:

With reference to Fig. 1, and assuming that the shear pin 22 is intact and that arm 48 of disc 45 is engaging said pin, the spring 42 will be under tension, as shown by *be full lines in said 63 designates a cover, which cover is i figure, and the toggle switch 52 will be in the position shown in Fig. 8,'to complete the electrical circuit to the motor.4 from the service wires 56 by way of the conductors 57 and 58. At this time the electrical circuit to bell 61 is severed. Then assume, for example, that some foreign matter in the coal, such as a railroad spike, rock, or the like, becomes entangled with the feed screw 37 suiiiciently to jam the latter and stop the same, the shear pin 22, being the weakest part between the driving and driven elements of the stoker unit, will be sheared oif between the driving collar and the reduced end of shaft 23. When shear pin 22 is thus broken, due to the stoppage of the feed screw 37 the hollow shaft 13, still being driven by the motor 4, will move that portion of the pin 22 Held in the collar 20 out of the notch 49 in arm 48, whereupon the expansion spring 42 will cause the tubular member 40 to be moved outwardly relative to tubular member 39 and as the disc 45 is fixed to the tubular member 40, said disc will engage the control lever 54 of the toggle switch 52 and move it from the position shown in full lines to the position shown in dotted lines in Fig. 1. This movement of the control lever 54 breaks the circuit of conductors 57 and 58 to motor 4 and simultaneously completes the circuit to conductors 59 and 60, the closing of the latter circuit thus operating the bell 6l to notify the attendant that the unit is at a standstill, whereupon it is only necessary' for the attendant to remove the cover 63 and loosen the locking screw 50, whereupon the switch control unit can be removed from the squared end 24 of the shaft 23 and the broken shear pin 22 removed and replaced by a new pin, it being understood, however, that the foreign matter entangled with the feed screw 37 be located and removed. The switch control unit is then replaced upon the squared end 24 ofV shaft 23 and the arm 48 again engaged with the new pin 22 and the toggle switch 52 moved so as to sever the electrical circuit to the bell 61 and complete the electrical circuit to the motor 4, after which the cover 63 may be replaced and the unit again ready for operation for driving the feed screw 37 and the forced draft fan.

While I have shown and described one particular embodiment of my invention as installed upon an underfeed stoker drive, it is to be understood that various changes and modifications may be made without departing from the scope or spirit of the invention, the invention being limited only by the claims hereto appended.`

What I claim as new and desire to secure by Letters Patent is:

1. In a device of the class described a member, motor means for driving said member, a driven member, means including a shear pin for connecting said driving and driven member, means including devices o n said driving and driven members normally stationary when the shear pin is intact but relatively movable on failure of said shear pin and controlling means operable on relative movement of said devices.

2. In a device having driving and driven members of a unit employing a shear pin to unite them, a motor for said driving member, a feed screw actuated by said driven member, a warning signal, a control switch for said motor and said warning signal, conductors from said signal an-d from said 'motor to said control switch `and means for operating said switch to stop said motor and operate said Signal when said pin is sheared due to stoppage of said feed screw, substantially as descn'bcd and for the purposes speciiled.

3. In a device having driving and driven members, with shear pin means connecting said members, a motor for said driving member, a switch, a warning signal, electrical conductors connecting said switch with said motor, electrical conductors connecting said switch with said signal, conductors connecting said switch with a source of electricity and a switch actuating means operated when said pin shears to operate said switch whereby the electrical circuit to said motor is severed and the electrical circuit to said warning signal is completed, in a manner substantially as set forth and for the purposes specified.

4. An automatic cut-off and warning signal comprising the combination of a driving member, a driven member, shear pin means connecting said members, a tubular member xed for rotation with said driven member, a tubular member telescopically received over said first mentioned tubular member, means for rotating said tubular members in unison, an arm fixed upon said last mentioned tubular member and having a notch therein adapted to receive and engage a part of said shear pin means, a spring `mounted within said rst mentioned tubular member to normally exert outward pressure against said second mentioned tubular member, switch-operating means 1 05 carried by said second mentioned tubular member,

a switch in the path of said switch-operating means controlling the electrical circuit of said driving member and a warning signal having its electrical circuit also controlled by said switch whereby during normal operation of the stoker the electrical circuit to said driving member is completed through said switch, and

the electrical circuit to said warning signal issevered, and whereby upon shearing of said pin said switch-operating means is moved by said spring to actuate said switch which severs the electrical circuit of said driving member and completes the electrical circuit to said` warning signal.

5. In combination with driving and driven members of a unit employing shear pin means to unite them, a motor for said driving member, a warning signal, a switch having operating means for controlling the electrical circuits to said motor and signal and including means to automatically stop said motor vand operate said warning signal upon shearing of said pin comprising an inner tubular member fixed with said driven member, an Outer tubular member received over said inner tubular member, a guide pin carried by said inner tubular member and. protruding through an elongated slot in said outer tubular member, a spring retained within said inner tubular member adapted to normally\exert outward pressure against said outer tubular member, a projection carried by said outer tubular member and adapted to be moved in the path of said switch-operating means, an arm on said projection provided with a notch which normally receives one end of said shear pin means, said arm being fixed with said projection whereby said .shear pin means is removed from the notch in said arm when said pin is sheared which permits the outer tubular member to move relative to the inner tubular member by action of the spring and carry said projection into engagement with the switch to sever the motor circuit and complete the warning signal circuit, substantially asset forth and for thepurpc'ses specied. FRANK J. SCHLO'IMAN.

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