US2016332A - Elevator safety device - Google Patents

Description

Oct. 8, 1935 4 LEE 2,016,332

ELEVATOR SAFETY DEVICE Filed April 29, 1933 Z INVENTOR ATTORNEY Patented Oct. 8, 1935 UNITED STATES PATENT OFFICE ELEVATOR SAFETY DEVICE Thomas Lee, Westfield, N. J.

Application April 29, 1933, Serial No. 668,484

11 Claims.

This invention relates to safety devices for elevators, or her cable-operated apparatus.

An object of the invention is to provide an elevator of the cable type with an improved automatic signal for warning the operator when the elevator is loaded to its safe capacity. Another object is to provide such'an elevator with a similar signal for warning the operator when the elevator is overloaded. An elevator may be I equipped with either or both of these signals, and the invention comprises novel features and combinations of elements by which the stretch of the elevator hoisting cable operates the signals.

Still another object of the invention is to provide means for preventing the starting of an overloaded elevator. Although the brake will usually holda heavily overloaded elevator before it is started, the brake is often unable to stop the car again after it begins to descend. I

The invention can be conveniently and economically applied to conventional elevators of the cable type to signal the operator when the elevator is loaded to capacity or overloaded, and to prevent starting of the elevator when overloaded.

Other objects, features and advantages of the invention will appear or be pointed out as the description proceeds.

In the accompanying drawing, forming a part hereof:

Fig. 1 is a diagrammatic view, partly in section, of an elevator equipped with safety devices according to this invention.

Fig. 2 is an enlarged sectional view on the line 2-2 of Fig. l.

Fig. 3 is an enlarged plan view of the collar on the hoisting cable.

Fig. 4 is a diagrammatic view, on a reduced scale, showing a modified form of the invention.

An elevator H has a beam it to which is attached a hoist cable IS. A ceiling I! under the beam i3 has a door it for access to control mechanism'above the elevator ceiling.

Signal lamps 2i and 22 are located in the elevator in position to be easily visible to an operator standing by a conventional controller 24.

The hoist cable l5 passes over drums 28 and 21 at the top of the elevator shaft, and is connected toa counterweight 29. The drum 26 is rotated by a reversible electric motor 32. A brake 34 is applied by a spring 36 with suflicient force to prevent the motor 32 and drum 26 from turning when the elevator is loaded and the motor circuit open. A solenoid 38 in series with the motor releases the brake 34 whenever power is sup-,-

1 plied to the motor to drive it" in either direction.

scribed is illustrated diagrammatically in its simplest form for a clearer understanding of the invention, but it will be understood that the invention is not limited to elevators having only one cable, or to elevators having the simple direct motor drive shown in Fig. 1.

A bracket comprising a vertical sleeve 40 and base 4| secured to the beam l3,'or to some other part of the-elevator, and a cylindrical support 42 fits into the sleeve 40. The support 42 is freely slidable in the sleeve 40 but is prevented from rotating by pins 44 which are fixed to the support 42 and extend into vertical slots 46 in the sleeve 40.

The support 42 can be moved up and down, and can be held in any set position by a screw 48, best shown in Fig. 2. The screw 48 threads through the base 4i and has an unthreaded upper end which extends into a recess in the bottom of the support 42. The screw 48 is held in this recess by a pin 50, which extends into an annular groove 52 in the screw.

The screw 48 passes through the web of the beam l3 and has a handle 54 on its lower end. This handle is accessible from within the elevator when the door I9 is open. By turning the handle 54 to the right or left, the support 42 can be raised or lowered in the sleeve 40. Electric switch members carried by the support 42 are thus moved up or down with respect to the elevator.

Five electric switch members GI, 62, 63, 84 and 65 are held between insulating blocks 81 and 68 by screws 69 which pass through the electric switch members, but are insulated therefrom by insulating bushings surrounding the screws. These screws 69 thread into the top of the support 42. Insulating blocks are located between the electric switch members.

The electric switch vmembers are made of spring metal and are shaped so that their ends are normally spaced from one another, except the ends of the switch members Bland 84 which are normally in contact.

A switch operating member comprising a split collar 12 is clamped to the hoist cable l5 by screws 14 (Fig. 3).

Referring again to Fig. l, the switch member Bl extends over the collar 12 a short distance. above the collar when the elevator is not loaded. As the elevator is loaded, the cable i5 .stretches slightly and the collar 12 moves up into contact with the switch member II and bends this switch member upward into contact with the switch member 62 when the load in the elevator is approximately equal to its safe carrying capacity.

A lug ll, ilxed to the switch member 62, extends through an opening in the switch member 63 without touching the latter. The upper end oi the lug it touches the underside of the switch member 84 or is very close to it when the switch members are in their normal positions. I

When the cable I! stretches enough to move the switch member l! into contact with the switch member 82, the circuit through the signal lamp 2i is closed and the lamp is lighted to indicate that the elevator is loaded to its safe capacity. Additional loading of the elevator causes the cable I! to stretch further so that the collar 12 bends the switch members ti and 62 further and causes the lug II to move the switch member 04 away irom the switch member ll and into contact with the switch member I.

The switch members SI and N are in the motor circuit in series with the controller 24, and when these members are moved apart the motor circuit is open and the elevator can not be started. The

- member 84 touches the switch member ti.

The spacing of the switch member '5 above the switch member I4 is very small so that when the latter moves out of contact with the member 63 it immediately moves into contact with the member 65, thus opening the motor circuit and lighting the overload signal lamp at substantially the same time. There is a sheet of insulation I8 on the under side of the switch member 83 so that no circuit is ever closed between the switch members I2 and OI.

The position oi the switch members Bi-BS is set by the handle 54 so that when the elevator is stationary and is loaded to its safe capacity, or

any chosen load less than its safe capacity, the stretch of the cable causes the collar 12 to move with respect to the elevator and. switch members a suillcient distance to move the switch member Bl into contact with the switch member 82 and light the warning or capacity signal 2|. Moving the handle 54 in a direction to lower the switch members causes the signal lamps to light when there is less load on the elevator. when the support 42 and switch members I l" are raised, a heavier load is required to stretch the cable ll sunlciently to cause the signal lamps to light. I! the cable it becomes permanently stretched after a period of service, the handle 54 is operated to set the switch members "-8! higher and thus compensate for the permanent stretch of the cable.

The switch members I48 are located in posi-:-

tion to operate the signals at certain predetermined loads on the elevator when the latter is stationary. Acceleration of the elevator when going up, and deceleration when going down, put an additional load on the cable. Thus, the cable of a safely loaded moving elevator may be stretched further than that 0! an overloaded stationary elevator. It is, therefore, desirable to prevent the signals and motor cut-out from operating when the elevator is moving.

A relay II is connected in series with the motor ll. As soon as power is supplied to the motor to start the elevator. the relay Ii is energized, closes a normally open switch 82, and completes a shuntcircuit around the switch members 83 and '4 so that the motor-circuit can not be opened by these switch members moving apart while power is being supplied to the motor.

The signal lamps 2| and 22 are supplied with power through a switch 84 which is closed when the controller 24 is in its neutral position but is opened whenever the controller is moved out 0!- neutral position.

The circuit for the motor 32 and the circuits for the signal lamps 2|, 22 are separate, so that they can be operated on different voltage. The switch members Bl-GS and the controller 2i are shown connected directly in the lamp and motor circuits,

but it will be understood that relay switches can be used to carry the lamp and/'01 motor currents if it is desir able to have only small currents flowing in the switch members and controller.

' Fig. 4 shows a modified form or the invention, which diilers from the embodiment illustrated in Fig. 1 only in the structure for transmitting the movement of the collar 12 to the switch members "-65. When the invention is applied to elevators having a plurality of hoisting cables, the collar i2 is secured to one-oi the cables but the stretch of each cable is relatively small. In Fig. 4 the collar 12 is placed higher above the elevator and the length of cable between the collar and elevator is thereby increased.

A third-class lever II is pivotally connected to a bracket 90 on the elevator. A weight 82 at the free end of the lever 88 operates the switch members in the same way that the collar 12 operates them in Fig. 1. The collar is connected to the lever 88 by a cable 94, or other tension member. When the hoist cable I! stretches, the collar 12 moves upward with respect to the elevator and moves the lever 88 so that the weight 92 rises. The cable 94 and lever 88 are motion transmitting connections through which the movement of the collar 12 is transmitted to the weight 82, which is the switch operating member in Fig. 4. These connections multiply the the weight is further from the fulcrum oi the lever 88 than is the connection with the cable 54. Thus a small cable stretch can be made to cause a relatively large movement oi the switch operating member.

The operation oi! the invention is as follows:

When the elevator is unloaded, or carries a load less than its safe capacity, the switch members I. and BI are in contact so that movement of the controller 24 completes the motor circuit, releases the brake 34, supplies power to the motor 34, and causes the elevator to go up or down, depending on the direction of movement of the controller. The switch members ii, 62 and 85 controlling-the circuits of the signal lamps 2| and 22 are in open circuit positions, and the signal lamps are therefore not lighted.

As the load on the elevator increases until it is approximately equal to the sale carrying capacity of the elevhtor, the cable ll stretches, and the elongation of that portion of the cable be tween the collar I2 and the cable connection'to the elevator causes the collar to move upward and bend the switch member 6| into contact with the switch member 62. The controller 24 is in neutral position when the elevator is being loaded, and thus a circuit is closed through the switch 84. signal lamp 2i and switch members 8i and '2. The signal lamp 2| is lighted to indicate that the load on the elevator is approximately equal to its safe capacity. The elevator can be started when the signal lamp 2i is lighted and the lamp will go out as soon as the controller 24 is moved to start the elevator.

when the elevator is overloaded, the cable tween the switch members 64 and 65 closes the circuit from the switch 84 through the overload signal lamp 22, and with the controller 24 in neutral position the lamp 22 is lighted to indicate that the elevator is overloaded and can not be started. Movement of the controller will extinguish the lamp 22 but will not release the brake 34 or start the motor 32. Any suitable signals can be substituted for the lamps 2| and 22. The invention can be applied to elevators or other hoisting apparatus in which the hoist cable is operated by otherpower means instead of an electric motor. The preferred embodiments of the invention have been illustrated and described, but changes and modifications may be made and various features of the invention used with or without other features without departing from the invention as defined in the claims.

I claim:

1. Hoisting apparatus including a hoisting cable, load carrying means supported by the cable, a signal for indicating that the load on the cable exceeds a given weight, and means operated by stretch of said hoisting cable to cause display of the signal, said means including a member attached to the cable and movable with the cable in its direction of stretch, and a relatively fixed member.

2. The combination with a hoisting apparatus having a hoisting cable, of a warning signal and an overload signal; means operated by the stretch of the hoisting cable, when the hoisting apparatus is loaded to its safe capacity, for operating the warning signal; and means operated by. further stretching of the cable for operating the overload signal.

3. Ina .cable hoist elevator, a signal for indicating that the elevator load exceeds a given weight; signal operating mechanism including members carried on the elevator; and means connected to the cable and movable with respect to the elevator and said members as the cable stretches with increased ,load on the elevator, said means being movable in the direction of cable stretch and located in positionto cause the signal to be operated when the cable is stretched an amount corresponding to a predetermined load.

4. The combination with a cable hoist elevator, of an electric signal; switch means carried bythe elevator; switch operating means including a member connected to the hoisting cable some dis-' tance above the elevator and movable" with respect to the elevator and switch means as the section of cable between said member and the elevator stretches with increase of load; and

means for changing the location of the switch means to compensate for permanent stretchot the cable or to set the switch means for operation at a different elevator load.

5. The combination with an elevator having a ceiling and a hoist cable, of a signal; signal oper-. ating means including members connected with the elevator above the ceiling, and an element connected to the hoist cable some distance above the elevator and movable with respect to the ele-,

vator and said members as the hoist cable stretches with increased load; and adjustment means above the ceiling and accessible to a person in the elevator, through an opening in the ceiling, for changing the location of said mem- 5 bers to compensate for permanent stretch in the cable or to set the signal operating means to operate for a different elevator load.

1 6. An elevator safety device comprising a signal; and mechanism for operating the signal when the load on the elevator exceeds a given weight, said operating mechanism including an element connected to the cable and movable with respect to the elevator when the cable stretches with.in-

creasing load; and motion multiplying lever onnections for t ansmitting the movement of said element to other parts of the signal operating mechanism.

'7. In combination with an elevator, a motor for operating the elevator, a controller for the ele- 2o vator; and means operated by stretch of a sup porting cable of the elevator to prevent operation of the elevator.

8. The combination with an elevator having a hoist cable and drum; an electric motor for rotating the drum; a brake for the drum and motor; electromagnetic means for releasing the brake; and a controller for the elevator for supplying power to the motor and the brake-release means; of a normally closed switch in the controller circuit, and means including a member attached to the cable and movable with stretch of the hoisting cable, when the elevator is overloaded, to

open said switch so that the controller cannot supply power to the motor and brake release means.

9. In combination with an elevator, a hoist cable and drum, a motor for rotating the drum,

a brake for stopping the motor and drum, and r for holding them against rotation; a controller 40 for the elevator for releasing, the brake and sup-- plying power to the motor; signal means operated by stretch of the hoist cable for indicating when the elevator is loaded to its safe capacity; and means operated by a further stretch of the hoist 5 cable for rendering the controller inefiective.

10. The combination with an elevator having a hoist'cable and drum; an electric motor for rotating the drum; a brake for the drum and motor; electromagnetic means for releasing the brake; and a controller for .the elevator for supplying. power to the motor and the brake-release means; of an electric signal and switch means controlling the operation of the signal to indicate when the elevator is loaded to its safe capacity; a normally closed switch in the controller circuit and separate from the switch means of said signal so that the signal circuit can be operated with a voltage different from that of the motor circuit; and means operated by stretch of the hoisting cable, when the elevator is overloaded, to open said switch so that the controller cannot supply power to the her to cause a display of the signal when the cable stretch reaches a given value.

THOMAS LEE. T5

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