US1613216A - Overload-stopping device for elevators - Google Patents

Description

W. J. ALBERSHEIM ET AL I OVERLOAD STOPPING DEVICE FOR ELEVATORS Filed Dec.

Jan. 4, 1927.

Patented Jan 4, 1921.

UNITED STATES 1,613,216 PATENT OFFICE.

WALTER J. ALBEBSHEIM- AND HARVEY S. KONHEIM, OF NEW YORK, N. Y.

OVEBLOAD-STOEPING DEVICE FOE. ELEVATORS.

Application filed December 10, 1925. Serial No. 74,555.

This invention relates more particularly to a class of safety appliances for elevators.

My invention has for its object primarily to provide an overload stopping device de signed to be employed especiall in conjunction with electrically operate elevators for saving persons from likelihood of injury by cutting-out the hoisting means when overload is imposed on the car, and which is of a form wherein an indicator or. alarm causes a signal as a timely warning to be given to the o erator and assengers so that the load may opportundly lessened. The invention contemplates the provision between the hoisting cable andthe car of a yielding connection which operates a circuit controller for closing the circuit to sound the alarm and for simultaneously cutting-out the motor circuit when the car is under excess of load.

A further object of the invention is to provide an overload stopping device of a simple and eflicient form which may be employed in conjunction with elevators of various types.

With these and other objects in view, the invention will be hereinafter more fully described with reference to the accompanying drawing forming a part of this specifis cation in which similar characters of reference indicate corresponding parts in all the views, and will then be pointed out in the claims at the end of the description.

In the drawing, Figure 1 is an elevation, partly broken away and partly diagrammatic, of the car of an electrically operated elevator with one form of our improved overload stopping device applied thereto, and

Fig. 2 is an enlarged fragmentary view, partly broken away, showing parts for controlling the opening and closing of the electric circuit of the device.

In practice we may employ the overload stopping device in conjunction with the car A of any of the ordinary or preferred types of passenger or freight elevators, and the car is hoisted "and lowered by means of one or more cables, as B, which is operated in the usual fashionas by a motor preferably of a reversible typeadapted to be driven by the current of an electric circuit, as 11, which may lead from a suitable source of electrical energy, as 12.

The car A is suspended from the cable B by means of a yielding connection 13 which may be of a well known form of toggle composed of four links 14, 14, 14, 14 having the ends pivoted together, as at 15. 15, 15, 15, in a diamond shape so that the links are expansibly movable upwardly and downwardy as well' as laterally with relation to each other. On the top of the car A is secured, at 16, a base or plate, as 17, and the pivot 15 of the links of the toggle passes through a hole in the central part of the base plate 17. The pivot 15 of the links of the toggle passes through a hole in a block or head 18 held on the end of the cable B,,and the car and cable are thereby flexibly connected. To one end of the base plate 17 is pivoted, at 19, one end of an angular bar or lever, as 20, which extends toward one of the side walls of the car, and to the other end of the base plate is pivoted, at 21, one end of another angular bar or lever, as 22, which extends toward the oppo site side wall of the car. To the elbow of the bar 20 is pivoted, at 23, one end of a link 24 having its other end movably mounted on the pivot 15 of the links of the toggle 13, and to the elbow of the bar 22 is pivoted, at 25. one end of a link 26 having its other end movably mounted on the pivot 15 of the links of the toggle. The links 24, 26 are of lengths for holding the bars 20, 22 normally spaced above the top of the car A. On the free end of the bar on lever 20 is a weight or ball 27, and on the bar or lever 22 adjacent its free end is another weight or ball 28. The balls 27 and 28 are of sufficient weight to counterbalance the maximum load which the car A is designed to carry, and in their normal positions, as shown in Fig. 1, these counterbalancing weights movably hold the links of the toggle 13 in partly contracted positions by the force of their pull on the pivots 15, 15 and on the links of the toggle through the medium of the links 2 1. 26. On top of the car under the weights 27, 28 may be suitable stops or bufi'ers, as 29, 30 forcushioning and limiting the movements of the weights toward the top of the car.

Interposed in the electric circuit 11 is an indicator or alarm 31 which may be in the form of a bell adapted to sound or ring for giving a signal of warning when excess of load is imposed on the car, as will be later explained, and the usual controller switch 32 is provided to be manipulated by a person at 38, from the armature.

for operating the car. Also interposed in the circuit 11 is a solenoid, as 33, of any well known or preferred type. Attached, at 34, to a suitable part of the car is one end of an armature 35 which may be in the form of a spring strip so arranged that its free end portion will be attracted into contact with the core 36 of the solenoid when energized, and on the face of the armature opposite to the core of the solenoid is a conductive plate or block 37 which is insulated, Fastened, at 35). to the top of the car A under the free end of the bar 22 ot' the counterbalancing weight 28 is a plate, as 40, and extending upwardly from part of this plate in spaced relation to the bar is a strip 41 having on one of its faces two spaced contact blocks 42, 43. On the contact block 42 is a binding post 44, and on the contact block 43 is another binding post 45.

The current conductors providing the electric circuit 11 illustrated consists of a wire 46 which leads from the source of current supply 12 to one terminal of the motor 10. Also leading from the source of current is a wire 47 leading to a contact 48 which is positioned under the solenoid 33 for being engaged by the armature 35 when attracted to the core of the solenoid. To the wire 47 is connected a wire 49 having its other end portion helically twisted and flexibly connected to a binding post 51 provided on one end of a movable switch arm 52 of a circuit controller, as 53, as will be hereinafter more fully described. Connected to the second terminal of the motor 10 is a wire 54 leading to the controller 32 which is adapted to be closed upon a contact 55 having a wire 56 leading therefrom to one end of the winding of the solenoid 33, and leading from the second end of the winding of the solenoid is a wire 57 which is connected to the binding post 45 of the strip 41. Leading from the wire 57 to the armature 35 is a wire 58, and connected to the wire 46 is a wire 59 which leads to a contact 60 adapted to be engaged and disengaged by the insulated contact plate 37 of the armature 35. Leading from one pole of the alarm 31 is a wire 61 which terminates with a contact 62 in spaced relation to the contact 60 for also being engaged and disengaged by the insulated contact plate 37 of the armature 35," and leading from the second pole of the alarm is a wire 63 which is connected to the binding post 44 of the contact 42 of the strip 41 of the base plate.

The switch arm 52 of the circuit controller 53 has a body part, as 64, of somewhat the shape of the quadrant of a circle having its rightangular corner pivoted, at 65, to part of the base plate 40 which is opposite to the strip 41 of the contacts 42 and 43. Projecting from a portion of the body part 64 opposite to the pivot 65 is the end 66 which terminates at the strip 41 for being moved into and out of engagement with the contacts 42 and 43, and this free end 66 carries the binding post 51 which connects the wire 49 to the switch arm In the portion of the curved edge of the body part (34 of the switch arm 52 is a tooth, as 67. On the switch arm is a weight or ball 68 for causing the switch arm to swing on its pivot normally downward, and on the base plate 40 under the weight 68 may be a protruding lug (39 for serving as astop to limitthe downward movement of the switch arm, as shown in Fig. 2. Extending from the on central part of the switch arm is a pin 70. To the base plate 40 below the tooth (37 ot' the body part 64 is pivoted, at 71, the central portion of a pawl, as 72, which is preferably of a shape having a curved 5-3 pointed end 73 adapted to be moved into and out of engagement with the tooth (37 of the switch arm 52. The other end part of the pawl 72 extends in a direction below the counterbalancing weight 28 of the bar 22 of the toggle 13, and on the second end of the pawl may be a weight 74 for serving to normally swing the pawl on its pivot so that its pointed end 73 will tend to engage the tooth 67 of the switclrarm 52. On the pivot 65 is fulcrumed the central part oi a lever or bar, as 75, of such a length that one of its ends extends under the pin 7 O of the switch'52 for movably engaging the pin, and the other end of this lever extends under the free end of the bar 22 or the counterbalancing weight 28. To the second end of the lever 75 is pivoted, at 76, the upper end of a link 77 having in its lower end a slot 78 in which is movably disposed V3 a pin, as 79, which protrudes from part of the pawl 72 bet-ween its pivot 71 and its weight 74. To the free end of the bar 22 of the counterbalancing weight 28 is pivoted.

at 8U, the upper end of another link 81 having its lower end slotted, as at 82, and through this slot is movably disposed a pin 83 which extends from part of the lever 75 between its fulcrum G5 and its pivot 76. The parts of the circuit controller 53 as described are so proportioned that when the balancing weight 28 moves .upwardlyand downwardly the end 66 will move into and out ofi engagement with the contacts 42 and 43.

Vhen the load on the car A is at or under the limit of its normal carrying capacity, the bars 20, 22 of the toggle 13 will be in their normal positions with the counterbalancing weights 27, 28 being lowered upon or in proximity to the stops or buffers 29, 30 on the top of the car, as shown in Fig. 1. The links 81, 77 will likewise be in lowered positions. The lever 75 will then be swung into engagement with the pin 70 of the switch arm 52 to position the free end 66 into engagement with the contact 43,

and the weight 74 will cause the pawl to the engagement of the insulated contact 37 with the contacts 60, 62 of the wires 59, 61. will be severed for cutting-out the alarm. The circuit will be closed from the source of current 12, over wire 46 to one terminal of the motor 10, and the circuit will also be closed from the source of current-over wire 47, through contact 48, through armature 35, and over wire 58, over wire 57, through the solenoid 33, over wire 56, through switch 32 and over wire 54 to the second terminal of the motor 10. The circuit will also be closed from wire 47, over 'wire 49 to contact 43 and to wire 57. The

mot-or will thereby be operated for hoisting and lowering the car in the customary man ner. When an overload is imposed upon the car, the strain upon the cable willcause the bars 20, 22 to be swung upwardly. With the upward movement of the bar 22 the links 81, 77 of the controller 53 will move upwardly, causing the lever. 75 to free its engagement with the pin; 70 and causing the pawl 72 to disengage tooth 67. The weight 68 will then carry the end 66 down,- wardly for severing its engagement with the contact 43 and for engaging they contact 42 of the strip 41, as indicatedin Fig. 2. The circuit to the solenoid 33 and to the motor will then be broken, and the spring action of the armature 35 will cause its separation from the core of the solenoid, and with its reverse movement the contact plate 37 will engage the contacts 60, 62. The circuit will thereby be closed from the source of current over wire 59, through contact plate 37 andover wire 61 to the alarm 31. The circuit will also be closed over wire 49, through contact 42 and over wire 63 to the alarm. The alarm or hell will then ring to sound a signal of warning that the car must be relieved of its excess of load before the elevator is capable of being operated.

When the current has once been established through leads 49, 57, 54, and 46, armature 35 is. drawn by solenoid 33 into contact with contact 48, thereby completing a parallel circuit through lead 47 armature 35, and lead 58 to lead 57. Thereafter, the car is not responsive to overload, since even if end 66 moves out of contact with contact 43, the current will continue to flow through the parallel circuit just described. Thus, in the event of sudden stra'in being imposed on he cable after the car has started, such as by dynamic action of the motor which may cause the bar 22 to rise and the switch arm 52 to move from the contact 43 to contact 42 the motor will still continue to operate the car by reason of the circuit remaining closed through the engagement of by-pass contact 48 with the armature 35 which will also remain in engagement with the core of the solenoid 33. The alarm 31 will be prevented from sounding because of its circuit still being brokenby the contact 37 remaining separated from the contacts 60, 62.

It should be particularly noted that the force required to move the switch arm 52 to the position shown in Fig. 2 is greater than the force required to maintain it in that position. Thus when the bar 22 starts to rise, it first takes u the slack between pin 83 and slot 82. It t hen raises lever 75, taking up the slack between pin 79 and the slot 78, and finally raises pawl 72 out of engagement with tooth 67. As soon as this is done,

the weight 68 is released, and pin 70 presses on the outer end of lever 75, tending to hold the mechanism against a return to normal position. It will thus be seen thatthe circuit controller will respond to a predetermined overload, but that slight variations in the load will not cause the switch arm 52 to oscillate up and down, nor to assume an intermediate position. It will also be evident that the overload must continue for an appreciable length of time, say two seconds, before bar 22 will move far enough to break the main circuit. 7

In the foregoing'description, we have embodied the preferred form of our invention, but .we do not wish to be understood as limiting ourselves thereto as we are aware that modifications may be made therein without departing from the principle or sacrificing any of the advantages of this invention, therefore, we reserve to ourselves the right to make such changes as fairly fall within the scope thereof Havingthus described our invention, we claim as new and desire to secure by Letters Patent r p 1. The combination with an elevator car, a hoisting cable therefor, an electric circuit and a motor in the circuit, of toggle connections between the cable and the carand having counterbalancing weights for preventing the toggle connectionsv from actuating when the load on the car is below its maximum carrying capacity, an alarm in the circuit, a locked switch normally closing the circuit to the motor, means operative by the toggle connections actuating to release the switch for closing the circuit to sound said alarm and simultaneously cutting-out the motor circuit when the car is under excess of load, and means in the circuit to by-pass the current for retaining a closed circuit to the motor and to keep the car in operation as Well as keeping open the alarm circuit should said switch be operated by dynamic strain being imposed on the toggle.

2. The combination with an elevator car, a hoisting cable therefor, an electric circuit and a motor in the circuit, of toggle connoctions betveen the cable and the car and having counterbalancing weights for preventing the toggle connections from actuating when the load on the car is below its maxnnum carrying capacity, an alarm in the circuit, a switch normally closing the circuit to the motor, means releasably locking the switch, means operative by the toggle connections actuating for releasing the locking means and said switch to sound said alarm and simultaneously cutting-out the motor circuit when the car is under excess of load, and means in the circuit to by-pass the current for retaining a closed circuit to the motor and to keep the car in operation as well as keeping open the alarm circuit should said switcn. be operated by dynamic strain being imposed on the toggle.

3. The combination with an electric elevator having a cable, a car suspended thereby, a motor for actuating the cable, and an electric circuit for connecting said motor to a source of current; of a yielding connection between said cable and said car, a circuit controller operated by said connection for preventing said circuit being closed while the stress in the cable exceeds a certain amount, a normally open switch connected in parallel with said circuit controller, and means operable by thepassage of current through said circuit to close said switch.

4. The combination With an electric ele vator having a cable, a car suspended thereby, a motor for actuating the cable, and an electric circuit for connecting said motor to a source of current; of a yielding connection between said cable and said car, a circuit controller operated by said connection to prevent said circuit being closed while the stress in the cable exceeds a certain amount, a switch having a flexible element connected in parallel with said circuit controller, and a solenoid operable by the passage of current through said circuit to bend said flexible element to close said switch.

5. The combination with an electric elevator having a cable, a car suspended thereby, amotor for actuating the cable, and a main circuit for connecting said motor to a source of current; of a toggle connection between said cable and said car, means operated by said toggle connection to prevent the circuit being closed while the stress in the cable exceeds a predetermined amount, said means being inoperative, after the circuit has been closed, to break said circuit.

6. The combination with an electric elevator having a cable, a car suspended thereby, and a motor for actuating the cable; of a main circuit for connecting said motor to a source of electric current, a shunt circuit having an indicator therein, a switch in the main circuit, a toggle connection between said cable and said car, and means operable by said toggle connection to open the main circuit and close the shunt circuit when the car is overloaded.

7. The combination with an elevator having a car, a hoisting cable and an electric motor for actuating the cable; of a main circuit for connecting said motor to a source of current, a shunt circuit having an indi 'ator therein, means for opening the main circuit and closing the shunt circuit when the car is overloaded, a solenoid in the main circuit, and a bypass circuit adapted to be closed by said solenoid.

8. The combination with an elevator having a car, a hoisting cable and an electric motor for actuating the cable; of a main circuit for connecting said motor to a source of current, means operative to open the circuit, when the car becomes overloaded, a solenoid in said circuit, a resilient member adapted to be flexed by said solenoid, and a circuit for bypassing the current around the said means, said circuit being closed by the flexing of said resilient member.

9. The combination with an elevator having a car, a hoisting cable, and an electric motor for actuating the cable; a main circuit for connecting said motor to a source of current, a yielding connection between said cable and said car, means operated by said connection for preventing said circuit being closed while the car is overloaded, a solenoid in said circuit, a resilient member adapted to be flexed by said solenoid, and a circuit for bypassing the current around the said means, said circuit being closed by the flexing of said resilient member.

This specification signed this 9th day of December A. D. 1925.

WALTER J. ALBERSHEIM. HARVEY S. KONHEIM.

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