Патент USA US2404415код для вставки
July 23, 1946. 2,404,415 F. _F. TURNER vOVERLOAD SAFETY SWITCH FOR ELEVATORS Filed June 24, 1945 FIE-2* /45 [f r121 .22 16 F/oyc/ Turner am: Patented July 23, 1946 2,404,415 UNITED STATES PATENT OFFICE 2,404,415 OVERLOAD SAFETY SWITCH FOR ELEVATORS Floyd F. Turner, Toledo, Ohio, assignor to The Haughton Elevator Company, Toledo, Ohio, a , corporation of Ohio Application June 2-4, 1943, Serial No. 492,117 1 Claim. 1 (Cl. 187—29) 2 This invention relates to a safety device to which the car is suspended from the usual cables prevent the starting of an overloaded elevator. l3. Beneath beam Hi there is a switch beam The object of the invention is to avoid the start l4, securely fastened to beam I2 at its ends. A ing of an elevator car when overloaded. micro-switch I5 is mounted upon beam l4 and When an elevator car is overloaded, and it is 6 is opened by relative movement of the central started in the down direction, there is danger portions of beams 12 and I 4. If necessary, the that it cannot be stopped at the desired floor micro-switch may comprise desirable and suit but will continue downward into the pit, from able means for multiplying the relative move which it cannot be raised by the regular elevator ment of the beams. motor. This involves much trouble and delay 10 It will be readily understood that as soon as an excessively loaded car is suspended from the before the elevator is in use again, even where no injury to the apparatus is inflicted. cables, beam 12 is sprung slightly and its central In speeding up production for war purposes, portion moves upward relatively to beam l4, heavy loading of elevators is unusually common, which is not affected by the weight in the car. In Fig. 2 there is shown an arrangement where so that some safety device is needed. A device 15 in plate 16 is directly suspended from cables l3 which would in itself render the elevator inoper and the distance between that plate and beam ative upon there being exerted upon the floor of I2] is governed by the degree of compression of the car and excessive weight would not produce springs l1. Switch I 8 is opened when the springs the desired results. When an elevator is started or accelerated upward, the inertia of the load in 20 are compressed unduly. the car adds to the pressure due to the weight Fig. 3 indicates another arrangement wherein of load, so that the lifting device is normally the ends of beam I22 are attached to the car by arranged to have a starting or accelerating lift bolts l9 and the springs 20 about bolts l9 are ing force greater than the dead weight of the compressed by the weight of the car, opening maximum permissible load. For this reason, a 25 switch 2| on crossbeam 22 when the weight is device set to render the elevator motor inoper excessive. ative when a downward pressure was exerted These different arrangements do not exhaust on the car equal to the weight of a normal load the possibilities, but are by way of illustration would stop the car immediately after starting only. However, the arrangement shown in Fig. 1 even though the dead weight of the load was 30 is preferred because it is most easily applied to much under that permissible, while a device set many elevators now in use, and it operates sub for the maximum permissible downward pressure stantially independently of the location of weight on the car would permit its starting when greatly in the car. overloaded, and would not even stop the motor If the safety switch located and operated as after the car started in the downward direction. 35 described was in a circuit necessary for both the The purpose of this invention is to avoid these starting and the continued operation of the motor, di?iculties and prevent the starting of an over it would be open to the objection noted above, loaded car in either the upward or downward because it would stop the motor when accelerat direction while not interfering with the normal ing with normal load, or else allow the starting operation of the car when the load is not eX 40 of the motor with excessive load. To avoid this, cessive. the safety switch is located in a circuit the clos Minor objects and the details of the invention ing of which is necessary for starting the motor will appear as the description proceeds. but not necessary for the continued operation of In the accompanying drawing forming a part the car. One way in which this can be done is of this speci?cation, Fig. l is a diagrammatic 45 indicated in Fig. 4. In that ?gure the safety switch [5 is shown elevation, partly in section, of an elevator car showing one mounting of my safety switch. located in a circuit 25 leading from power line 25 to power line 21 through switch coil 28 and‘ Figs. 2 and 3 are views similar to Fig. 1, but starting switch 29. With safety switch 15 nor showing different mountings of the switch. Fig. 4 is a wiring diagram indicating the relation of 50 mally closed, the closing of starting switch 29 my new safety device to the normal operating energizes coil 28 and closes power line switches 30 and 3|, thereby energizing the motor of the In the form shown in Fig. 1 there is indicated elevator. At the same time switch 32 is closed an elevator car In containing a load ll. At the in bypass circuit 33, so that the current continues top of the car there is shown a crossbeam l2 by 55 through coil 28, regardless of whether switch mechanism of an electric elevator. 2,404,415 , 3 I5 is opened or closed, until the motor is stopped in the normal manner. In this way, it will be seen that the safety switch operates to prevent the starting of the 4 In an electric elevator apparatus, a car having a top cross member to which suspension cables are centrally attached, said member being at tached at its ends to rigid car frame parts and being capable of ?exing intermediate its ends to elevator motor when the car is overloaded, With Ci assume a longitudinal bow when the car is sub out interfering in any way with the operation of jected to a predetermined overload condition, a the car after the motor has started. second cross member ?xedly connected at its ends It will be readily understood that changes may to the ?rst member near the ends of said ?rst be made to adapt the arrangement to the wiring system otherwise in use with the elevator, the 10 member and remaining substantially rigid during ?exing of the ?rst member, and a normally closed essential feature illustrated being that there is a micro switch in a circuit which must be closed safety switch normally closed in a circuit essen for the elevator to operate, said switch being dis tial to the starting of the motor, and a bypass circuit for the safety switch, the bypass being provided with a normally open switch which is closed by the starting of the motor.‘ Having disclosed the invention so that those skilled in the art can make and use the same, , what I claim is: posed adjacent to the longitudinal center of said cross members and being operable by a ?exing of the ?rst cross member relative to the other under predetermined overload conditions to open the switch. FLOYD F. TURNER.