USRE15733E - Automatic brake for elevators - Google Patents

Description

Dec. 18 1923.

' P. KESTEN ET AL AUTOMATIC BRAKE FOR ELEVATORS Original Filed May 6, 1915 keis sued Dec. 18 19 2 3.

umreo STATES;

P TENT OFFICE. I

ram. xEs rEN, or HUOK LSHOEEN, NEAR AacnEn, AND HEINRICH OSBORNE, or nmrm-wrnmnasnoar, GERMANY, ASSIGNORS, BY MESNE ASSIGNMENTS, 'ro OTIS ELEVATOR COMPANY, OE N W YORK, N. Y., a CORPORATION or NEW JERSEY.

AUTOMATIC BRAKE FOR ELEVATORS.

Original No. 1,173,438, dated February 29, 1916, Serial No. 765,839, filed Kay 6, 1913. Application for I reissue filed September 29, 1923. Serial No. 665,664. v

T all whom it may concern: Be it known that we, PAUL Keenan and HEINRICH OSBORNE, citizens, respectively, of Germany, and the Czechoslovakian Repub- 6 lie, and residing. respectively, at Huckelshofen near Aachen, and Berlin-Wilmersdorf, Germany, have invented certain new and useful Improvements in Automatic Brakes for Elevators, of which the follow.- 10 in is a specification. his invention relates brakes for electric elevators.

When elevators travel at high speeds and have to convey heavy-loads it is diflicult to stop at exacty predetermined points. In spite of uick-acting braking devices the highly 10 ed cage will always travel a considerable distance beyond the desired end position owing to its momentum when the disconnecting contact-piece for the motor and for the application of the brake is so arranged that the elevator stops when running empty in the desired position. Such elevators are therefore frequently caused to travel at a reduced speed before they reach the stopping place, so that the brake is ap.-'

' plied for only a short distance both when the elevator is light and when it is fully loaded, whereby greater accuracy in reaching the correct stopping place is obtained. Even when this method is used it is not ssible .to reach the prescribed point a solutely exactly. According in each instance to the magnitude of the load on the elevator the cage remains stationary within a certain distance of the required position. On the other hand, the described arrangement has the considerable disadvantage that the average speed of travel is materially dimin- 1 4o ished by the high speed ceasing prematurely.

A primary object of this invention is to provide an automatic brake for elevators such that there is no need to reduce the speed before running to the stopping place. The cage is to be able to travel at full speed as far as every stopping place, so that all loss of time owing to premature slowing of the entire elevator is obviated. In the event of the cage running past a predetermined limit, say in consequence .of its momentum when greatly loaded, the direction of rotation of the driving motor has to be reversed as rapidly as possible, so that the cage returns time is connected with its traveling back into' its correct position.

The reversal of the direction of rotation of the motor, which is preferably driven by a controlling generator connected on the field of this generator being reversed. For example, this generator may be provided with a separate field winding which is independent of the main windings and is trav ersed by the current'only when the cage travels past the desired end position and then in an opposite direction to that in which the current has previously traversed the main windings. magnetic field as rapidly as possible to its final value, large resistances may be connected in series with this auxiliary winding. so that the time constant of the circuit is very small. It is to be understood, however, that any other method of rapid excitation ma be employed if desired.

fter the direction of rotation has been reversed and when the cage is travelin into its'correct stopping position, in or er to prevent the elevator-motor having to work against the action of the already applied brake, the brake-magnet which prevents the application of the brake is preferably ener gized by the current used for reversing the In order to bring the Leonard system, is brought about by the automatic excitation of the controlling generator.

WVhen the motor runs in the opposite direction the brake is then taken off and applied again only in the desired end position of the lift.

The improved automatic brake for ole-- the third arm 25 of this leveris pivotally connected with the handle 26 of a second end switch 27 V In. the position a of the cage shown. in the drawing, i. e., shortly before the cage moves into the desired ition b, when it is still moving at the full v vorking speed, the following circuit is closed :-plus terminal of a source of current. 28, switch 24 and its contact plate 29, conductor 30, solenoid 31 of the brake-magnet 17, the conductors 32 33, and the minus terminal of the source oi current 28. The magnet 17 is consequently drawn into the solenoid 3 1 and the brakeblock 14 is removed from the brake-disk 12.

In the desired position b of the cage the roller 21 has run onto the stop 34 mounted on the cage, so that the lever-arm 22 and the handle 23 are moved into the position .b" and the lever-arm 25 and the handle 26 into the pgsitionb". The above-mentioned circuit is conse uentl broken and the brake is ap lied. en t e cage 1 travels past the esired lpgsitionb the roller-21 runs farther up t stop 34. In the ition .c

of the cage the lever-arm 22 and t e handle 23 are moved from the position b to c and the third lever-arm 25 and thehandle 26 are moved from the position b" to c". In this position the following circuit is closed by the switch 27 :-the source of current 28, conductor 35, contact-plate 36-and switch 27 wire 37, the second 'shunt'winding 38 of the generator 9, resistance 39, the wire- 33'and the source of current 28.

The auxiliary winding 38 when energized will cause the reversal of the generator 9, The solenoid 31' of the' magnet 17 is connected in parallel therewith over the contact-plate 36, the handle 26 of the switch27, the contact-plate 36', and the wires 40 and'32 so into the positions 6' and 6'', me

that the brake-block 14 issimultaneously removed from the ,disk 12. The motor 7 then changes its direction of rotation and lifts the ca 1 back into the desired position b, the t rec-armed lever 20, 22, 25 being likewise moved backward by the sprin 41. The lever-arm 22 and the handle 23, an the lever-arm 25 and the handle 26 thus return ctively, so that no, current flows in the so enoid 31 or in the auxiliary field-winding 38 of the generator 9. The brake is again applied and the cage stops in the desired position b.

- When thedisconnecting stop 34 returns,

that the handles 23, 26 of the switches 24 and 27, respectively, are returned intoj the three-armed'lever 20, 22, 25 is returned by the spring 41 into its initial position so their initial positions a. and a", respectively, the brake being again released by the switch 2i as" describedabove. and the cage 1 being' able to be. moved forward or be ward in known manner again.

Obviously the herein described apparatus can be used for any desired, number of stopping places of the-elevator and also ior both directions of .travel.

' We claim: 3 "1. The combination with a controlling generator, and a motor driven thereby on the Leonard system, of an auxiliary fieldwinding on said generator for reversingthe field thereof, a cage of an elevator and means controlled by said cage for energizingsaid field-winding when the 'c has passed a predetermined point and e'energizing the same when the cage has returned to said point. p I 2. The combination with a controlling nerator, a motor driven thereby on, the

onard system and an electromagnetic brake for the motor, of a normally closed circuit including the windin of said electromagnetic brake,.a norma yo 11 second circuit including an auxiliary fie d-winding on said generator for reversing the fiel thereof, a cage of an elevator and means controlled bysaid cage for first opening the first circuit when the cage passes a etermined point, then closing both this circuit and the second circuit when the cage has run beyond this point, and finally re opening both circuits when the cage has returned thereto.

3. The combination with a controlling ginerator, a motor driven thereby on the onard system and an electromagnetic brake for the motor, of a normally closed circuit including the windin of said electromagnetic brake, a norma y open second circuit in parallel with said winding and including an auxiliary field-windin on said generator for reversing the field t ereof; a cage of an elevator and means controlled by said cage for first opening the first circuit when the cage p a redetermined point, then closing both thi s circuit and the second circuit when the cage has run Raging this point, ang fintallly reopening t o sai clrcnitsw en ecage has returned thereto.

94. The combination with a controlling Enerator, and a motor driven thereb on e Leonard winding on and generator for reversing the field thereof, a resistance in series with said field-windingha cage of an elevator and means contro ing said field-winding and mistance w at system, of an auailiary aid ed by said cage for the cage has passed a predetermined pointand deenergizmg the same when the cage v cage of an elevator and electric means eon trolled by the cage ,for reversing the motor t e Leonard system, of a cage of an matic means has returned to said point.

- 5. The combination with a controlling generator, and a motor driven thereby, of a when the cage has passed a predetermined point and automatic means for stopping the cage when it' has returned to said point. I

6. The combination with a controlling erator, and a motor driven thereby eim evator and electric means controlled by the cage for revers' the motor when the cage has passed a re etermined point and autoor stopping the cage when it has returnedto said point.

' 7. The combination with a controlling nerator, a motor driven thereby on the mud system, the cage of an elevator, and

means controlled by 'said cage for reversing the field of the controlling generator when the cage has passed'a predetermined point and for automatically de-energizing the field of said controlling generator when the cage has returned to said point.

8. The combination with a controlling generator, and a motor driven thereby on the Leonard system, of a of an elevator and electric means controlled by the cage for revel-sin the motor when the cage has passed a' p etermined point and automatic means including an electromagnetic brake for stogping the cage when it hasreturned to sai point.

In testimony whereof, we have si ed ournames to this specification, this 25t day of August-1923,

PAUL KESTENa HEINRICH OSBORNE.

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