US2707531A

US2707531A - Elevator safety brake

Info

Publication number: US2707531A
Application number: US419641A
Authority: US
Inventors: Bartolomeo Nicola Di
Original assignee: Individual
Current assignee: Individual
Priority date: 1954-03-30
Filing date: 1954-03-30
Publication date: 1955-05-03
Anticipated expiration: 1972-05-03

Description

M y 3, 1955 N. m BARTOLOMEO ELEVATOR SAFETY BRAKE Filed March 30, 1954 United States Patent In my United States Letters Patent No. 2,634,829

granted April 14, 1953, for ElevatorSafety Brake, there is disclosed an emergency or safety brake mechanism for an elevator with means by which the brake may be released momentarily and repeatedly by the operator from within the car, so that should the elevator car have been stopped by the brake between landings, the car can be allowed to lower by repeated short distances until it is opposite to a landing. .The car door may be then opened and the passengers allowed to pass out sothat they are not imprisoned indefinitely in the car between landings due to the operation of the brake.

The duration of each brake release issubstantially out of control by the car operator so that even should he become frightened or even. should he be panic stricken by the emergency which caused the brake ,to become operative, he cannot by the merely momentary-release of the brake subject himself and his passengers to dangerous conditions.

In my patent, the automatic brake application is shown as occasioned by the breakage of a supporting cable for the elevator car.

In some jurisdictions it is now required that elevators be equipped with speed responsive devices and that an emergency brake be applied by such a device whenever the speed of the elevator car exceeds a predetermined-excess over a normal safe speed.

One object of the present invention, therefore, is to provide for automatic brake application set ;by such a speed responsive device should the car. speedbecome excessive to a predetermined point, as well asbe set by a breakage of the supporting cable, and to provideformovmentary repeated releases of the brake by action of the operator, thus to avoid any enforced lengthy entrapment of people within the elevator car should theautomatic devices act to first stop the. elevator car between landings.

For a more complete understanding of this invention,

reference may be had to the accompanying drawings in which Figure 1 is a fragmentary somewhat. diagrammatic elevational view of an. elevator car within thecar well, and

illustrating both the speed responsive .device and the cablebreakage responsive device operative independently of each other to set the brake.

Figure 2 is a detail sectional view to a larger scale on line 22 of Figure 1, the brake being shown released.

Figure 3 is a view similar to a portion of Figure 2, but" showing the brake applied.

Figure 4 is a fragmentary view to a larger scale of parts shown in Figure 1.

Figure 5 is a fragmentary elevational view similar to a portion of Figure 1, but showing a modification.

Figure 6 is a cross sectional view of the brake releasing switch.

Referring to the drawings, at 1 in Figure 1 is shown an elevator car which travels in a well at 2 between suitable guide rails 3 and 4. The elevator is suspended by cables,

to rise or descend in the well.

2,707,531 Patented May 3, 1955 Connected to be operated by the motion of the elevato is a speed control mechanism shown as comprising a centrifugal ball governor 10. As shown it is connected through an actuating shaft 11 and gears 12 and 13 with the shaft of the pulley 6 so that this speed responsive device is responsive to the speed of motion of the elevator car.

At 15 is shown an emergency brake mechanism which may be of any suitable type, but is that illustrated in my Patent No. 2,634,829 to which reference has been made. As shown best in Figures 2 and 3, it comprises a pair of side jaws and 21 pivoted to a shoe 24 and which may be brought into braking engagement with one of the ways, such as 4, of the elevator well, and may be pressed thereagainst as by a pair of

coil springs

22 and 23. The shoe 24 may be pressed against the edge face of the way 4, this shoe being carried by a slide 25 mounted within a casing 26. The release of the

members

20 and 21 are produced by suitable stops 20a and 21a with which the

jaws

20 and 21 engage when the shoe 21 is retracted.

Springs 27, shown best in Figure 4, act upon the rear end of the slide 25 to press the shoe 24 against the way 4 to applythe brake, but the three shoes may be retracted to release the brake as by the rocking in counterclockwise direction, as shown in Figure 4, of a rock shaft 28 to which is attached an arm 29 which engages in a slot 30 in the slide 25. This rock shaft 28 is provided with a double crankarm which is connected through an arm 36 to the armature 37 of a brake release solenoid 38. When this solenoid is energized the rock shaft 28 is turned in a direction to retract the brake shoes from contact with the member 4 against the pressure of the

springs

22, 23 and 27.

The rock shaft 28 has also secured thereto an arm 40 pivotally connected through a link 41 to the fulcrum 42 ofa lever 43. One end of the lever 43 has fixed thereto a cord 44 which passes up the elevator well and about a pulley 45 and thence extends to a portion of the winding drum 7 so that it winds and unwinds with the cable 5. It is normally under sufficient tension so as to pull the end of the lever .43 to which it is attached into the substantially horizontal position shown in Figure 1, but should the cable 5 break, the cord 44 will also break since it is unable to hold up the weight of the car, and this will release the tension on this cord, allowing the lever 43 to descend with its fulcrum point also, and permit the rock shaft 28 to be rocked in clockwise direction by the

springs

22, 23 and 27, thus permitting the application of the brake.

The other end of the lever 43 has connected thereto a second cord 50, which, as shown best in Figure 2, may pass about a pulley 51 from whence it passes to the winding drum 7 and is also held under tension so that with the tension applied to the cord 44, the rock shaft 28 is held in brake-released position. This pulley 51, as shown, is suspended from a lever 55 fulcrumed at a fixed point 56, one end of the lever 55 being connected through a pivoted link 57 to the axis of the pulley 51, and the other end normally passing between a pair of jaws of a fork 58. These jaws 58 are mounted for horizontal motion and are connected. to one arm of a bell crank lever 60, the other arm excessive, the balls fly out and the spool is lifted, withdrawing the fork 58 from engagement with the lever 55 and allowing thepulley 51 to drop sufficiently to release the tension on the cordand allow-the springs to set the emergency brake.

It will thus be seen that the cords 44 and 50 must both .be held under tension tomaintain the brake released, and

that if the speed of the car rises to a predetermined excessive point, the tension on the cord 50 is released, allowing the brake to be applied, or should the cable 5 part, the cord 44 also parts, releasing the tension thereon and also permitting the brake to be applied. Thus the brake is applied whenever either the supporting cable for the car breaks or the car reaches an excessive speed of travel. This brake may be released momentarily and re peatedly, however, as is shown in my patent hereinbefore mentioned.

The energization of the release solenoid 38 may be accomplished by the operator within the car by repeated manipulation of a handle 70 which is fulcrumed at 71 in a casing 72 and engages between spaced projections 73 and 74 from a switch 75. This switch is shown as of the mercury type, being fulcrumed at an intermediate point in its length as at 76 and supporting within a sealed container the mercury 77. When this switch 75 is caused to tilt from one side to the other, at an intermediate position the switch terminals 78 and 79 are in electrical connection with each other through the mercury 77, which permits the passage of current to the release solenoid 38, causing a momentary release of the brake. However, it will be noted that the operator cannot maintain the switch 75 in closed position, but can merely rock it from one to the other of its limiting positions in each of which the switch is open. The length of time the switch is closed is substantially wholly controlled by the inertia of the switch parts, any variation in speed of operation of the handle 70 by the operator being substantially without effect to vary the time that the switch is closed during each oscillation of the member 75. Thus the operator can not through excitement either speed up or slow down the time of release of the brake, which is substantially wholly controlled by the physical constants of the mechanism itself. By repeated momentary releases of the brake, the car can be allowed to descend or inch down should it happen to be stopped in between landings, so that it can be stopped finally at a landing where the door may be opened, allowing the escape of any one who would otherwise be entrapped in the car by the operation of the emergency brake.

In Figure 5 a modification is shown in which the applying of the brake by the speed responsive mechanism does not immediately disconnect the speed responsive means from further control, as it does in the arrangement shown in Figure 1, where once the fork 58'has been withdrawn from the lever 55, the speed responsive mechanism operative connection with the brake is disconnected and cannot be reestablished except by an authorized person.

In Figure 5 the speed responsive device a is in permanent control with the lever 55a so that the pulley 51a is raised or lowered as the speed of the car varies. With this arrangement the emergency brake applies a frictional drag to the motion of the car, and if this is sufficient to slow down the car to a normal speed, the brake is held partly applied and the car is not fully stopped, the governor or speed responsive device in this case acting merely to bring the speed of the car within limits though not interfering with continued operation thereof.

From the foregoing description of certain embodiments of this invention it will be evident that various changes and modifications may be made therein without departing from its spirit or scope.

I claim:

1. In combination with an elevator well, a car arranged to travel in said well, a cable suspending said car, a winding drum for said cable, a spring applied emergency brake for stopping travel of said car, means including a cord movable with said cable and operatively connected to said brake, means operatively connected to said cord and normally holding said cord under tension to thereby hold said brake released, means responsive to mechanism to release such tension and permit said spring to apply said brake, and a second cord movable with said cable and operatively connected to said brake and normally under tension to hold said brake released but breakable to release said tension on breakage of said cable and permit said spring to apply said brake.

2. In combination with an elevator well, a car arranged to travel in said well, a cable suspending said car, a winding drum for said cable, a spring applied emergency brake for stopping travel of said car, means including a cord movable with said cable and operatively connected to said brake, means operatively connected to said cord and normally holding said cord under tension to thereby hold said brake released, means responsive to the speed of motion of said car, means responsive to a predetermined excess of speed of said speed responsive mechanism to release such tension and permit said spring to apply said brake, a second cord movable with said cable and operatively connected to said brake and normally under tension to hold said brake released but breakable to release said tension on breakage of said cable and permit said spring to apply said brake, said operative connections between said cords and brake including parts common to both connections operative to permit application of said brake on release of tension in either cord.

3. In combination with an elevator well, a car arranged to travel in said well, a cable suspending said car, a winding drum for said cable, a spring applied emergency brake for stopping travel of said car, means including a cord movable with said cable and operatively connected to said brake, means operatively connected to said cord and normally holding said cord under tension to thereby hold said brake released, means responsive to the speed of motion of said car, means responsive to a predetermined excess of speed of said speed responsive mechanism to release such tension and permit said spring to apply said brake, a second cord movable with said cable and operatively connected to said brake and normally under tension to hold said brake released but breakable to release said tension on breakage of said cable and permit said spring to apply said brake, said operative connections between said cords and brake including a lever having arms connected to said cords and a fulcrum connected to said brake mechanism.

4. In combination with an elevator well, a car arranged to travel in said well, a cable suspending said car, a winding drum from said cable, a spring applied emergency brake for stopping travel of said car, means including a cord movable with said cable and operatively connected to said brake, means operatively connected to said cord and normally holding said cord under tension to thereby hold said brake released, means responsive to the speed of motion of said car, means responsive to a predetermined excess of speed of said speed responsive mechanism to release such tension and permit said spring to apply said brake, a second cord movable with said cable and operatively connected to said brake and normally under tension to hold said brake released but breakable to release said tension on breakage of said cable and permit said spring to apply said brake, electrically actuated means for releasing said brake, and operator actuable means for repeatedly and momentarily actuating said electrically actuated means to release said brake a predetermined excess of speed of said speed responsive landing should said brake have acted to stop the car between landings, the length of time of such momentary release being substantially out of control of the operator.

References Cited in the file of this patent UNITED STATES PATENTS 299,544 Holfnagle June 3, 1884 722,364 Holman Mar. 10, 1903 1,702,384 Hymans Feb. 19, 1929 2,634,829 Di Bartolomeo Apr. 14, 1953