US1386223A - Elevator control - Google Patents

Description

E. F. BANFIELD.

ELEVATOR CONTROL. APPLICATION man Diem, i918.

1,886,223. A n Patented Aug. 2,' 1921.

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UNITED STATES EDWIN F. BANFIELD, F ATLANTIC HIGHLANDS, NEW JERSEY.

ELEVATOR CONTROL.

Specification of Letters Patent.

Patented Aug. 2, 1921.

Application filed December 11, 1918. Serial No. 266,216.

To @ZZ whom t may concern Be it known that EDWIN l". BANFXELD, a citizen of the `United States, residing at tlantic Highlands, in the county of Monmouth and YState of New Jersey, have invented new and useful lniproveinentsin Elevator Controls, of which the following is a specification.

This invention relates to improve-ments inY elevator controls.

@ne of the objects of this invention is to provide an improve-d safety control for preventing," the. operation of the elevator car unless the car door is closed.

Another object is to provide an electrical safety control whereby the open condition of the car door prevents the operation of the elevator.

Another object to prevent the inadvertent starting of the ele 'ator duringI inspection, cleaning, adjusting, repairing, etc., while the car door is open.

further object is to provide for theautomatic adjustment of the safety mechanism.

Another object is to provide a. safety control which may be readily applied to existinaelevator equipment. n

`Other objects and advantages will appear from the specification and claims.

@ne embodiment of the invention is illustrated in the accompanying` drawing, wherein- Figure 1 shows, diagramniatically, the in- 'ention associated with electrical elevator vstern. and.

n Fig. 2 shows a modification of one of the eatures.

In its preferred embodiment the invention comprehends a flexible cable extending along the elevator shaft in a. position to be under the control of the car door in any position of the car. rThis cable actuates a safety switch which causes the operating moto-r to be disconnected from the line, to stop the car whenever the door is opened while the car is in motion, or to prevent the starting; of the car, if it is at rest, until the door is closed. To guard against the inadvertent starting,r of the car, by the manipulation of any part of the ordinary controller svsteni. during' inspection` cleaning, adjustment, repairs. etc., while the door is open, a. masten switch is provided for entirely removing' the power from the controller systeni uiitil the door is closed. Automatic adjusting` and compensating means are also provided to insure that the correct relation exists between the cable and safety switch so that the control is always able to function properly.

Fig. 1 will irst be described.

An elevator car 5 is adapted to be moved up and down in the elevator shaft or hatchway by an electric motor 6. The up-anddown movement is regulated by an operators-controller 7, carried in the car, through a` pair of electromagnetic direction switches 8 and 9. The power for operating the motor is supplied through a master switch 10 and is controlled by a series of accelerating switches 11, 12, 13 and 14. A flexible cable 15 extends along the elevator shaft and is actuated` by the car door to control the condition of a safety switch 16. Vhen the door is open the safety switch is also open. If the door is opened while the car is in motion the safety switch causes the immediateI opening of the direction Switch and the master switch and the car is stopped. Tf the car is at rest t-he opening' of the door causes the safety switch to open the master switch and the car cannot be started until the door is closed.

The flexible cable 15 is secured to the top of the elevator shaft and extends between two pairs of rollers 17 and 18 carried in iixed positions on the car. rThe cable also passes between a pair of rollers 19 secured to the free end of a. gate-actuated lever 20.

The cable and lever assume the positions.

shown in full lines when the door is closed and the positions shown b y the dotted lines when the door is opened.

At the bottom of the shaft cable 15 passes around a pulley 21 and then over a pulley 22 to which is secured the contact drum of safety switch 1G. A freely suspended weight 28 is fastened to the lower end of the cable to keep it taut and to compensate for stretchingf and contraction, as will be hereinafter explained.

The amount the pulley and drum can be rotated is limited by a pair of fixed stops 24: and 25 which are adapted t-o be engaged by an arm 26 carried by pulley 22. Safety switch 16 has a. pair of contacts 27 and 28 adapted to interconnect, respectively, two pairs of contacts 29 and 30 when the drum is in the position shown by the full lines and to disconnect them when the drum is in the position shown by the dotted lines.

The entire system can be fully understood there is no interruption in the field connections across the line, provides dynamic bralring to prevent excessive coasting of the car. This shortcircuit is broken by the energization of either switch 8 or switch 9 disconnecting the respective contacts 52 or There is, thus, no shortcircuiting of the line at the time it is connected to the armature by one of the direction switches.

lf, during the ascending of the car, the door should be opened, the lever 9.0 is moved to the dotted line position. This movement of lever 2O flexes the cable, rotating pulley 22 and the drum of safety switch 16 in the direction of the arrow and disconnecting contacts 29 and 30, as before. The disconnection of contacts SOvopens the circuit for the winding of direction switch 8. Switch 8 returns to normal position, interrupting the line connections to the motor armature 'and providing the dynamic brake shortcir cuit, through resistance 73, as previously described.

ln order that the motor may act as a generator to secure the proper dynamic braking action, it is necessary to maintain the field excitation of the motor until the car is stopped. This is accomplished by retaining the master switch closed in spite of the fact that the circuit for its winding through contacts 529 has been opened by the rotation of the drum of the safety switch. The master switch has an auxiliary pair of contacts T6, which are closed when the master switch is closed and open when the master witch is open. Accelerator switch 1e also has a pair of stationary contacts 77 adapted to be interconnected by a movable contact 78 when the switch is energized. rThese two sets of contacts control a by-pass circuit for winding 37, including conductors 79 and SO, which is independent of contacts 29. rlhus. when the master switch has once been closed, it is independent of safety switch 16 l`s long as accelerator switch 14 is energized. llhen, therefore, power is removed. from the perating motor by the opening of the door uri-ing the movement of the car, the master Nwitch remains closed and dynamic braking action is provided until the motor has so decreased its speed that accelerator switch 1e is denergized. The accelerating switches are usually denergized at aconsiderably lower currentvalue than that at which they operated so that the desired braking action can be readily obtained. rThe auxiliary switch need not be placed on the last accelerator switch but may be associated with any of the accelerating switches.

T he master switch can be readily arranged to be placed in a cabinet which can be made inaccessible to the ordinary cleaner and repairman. By having the by-pass circuit include contacts 76, it is thus impossible for the inadvertent manual manipulation of the In order to prevent the motor from being thrown upon the line without all the starting resistance in circuit, as might be the case if the operator could, by quickly reversing the position of arm 39 of his' controller, connect the motor armature in circ-uit in a reverse direction before the accelerating switches are denergized, the energizing circuits of the windings of direction switches 8 and 9 pass through contacts t9 on accelerating switch 11. These contacts are shunted by a resistance 81, which is sufficiently high to prevent the operation of trie switches 8 or 9 when it is in series with their operating windings. The shortcircuiting of this resistance by the de'c'nergizing of accelerating switch 11 allows suilicient current to flow, when controller arm 39 is made to engage contacts c or T2, to effect the operation of direction switch 8 or 9. Thus the operator cannot connect the motor to the line without all of the starting resistance being in circuit.

Fig. 2 shows a. modiiied arrangement for controlling the master switch by-pass circuit, to insure dynamic braking when the door is opened while the car is in motion. instead of having the by-pass circuit controlled by contacts on one of the accelerating switches, a counter voltage relay 82 may be connected across the motor armature. )i pair of lined contacts 83 and 84 of relay 82 are connected, respectively, to the positive line and the righthand auxiliary contact 76, These contacts then bear the same relation to the by-pass circuit as do contacts 7l' when the accelerating switch is used for the control. Then the counter voltage relay 82 is suiiiciently energized by the counter-electromotive force of the inotor, its armature interconnects contacts 83 and Se, closing the by-pass circuit of the master switch with the same result as previously described. The counter voltage relay arrangement is particularly adapted for equipments where the safety control is added to existing installations. No change need be made in the accelerating switches already in place. lt is also particularly adapted for elevator equipments which depend upon other means than counter voltage accelerating switches for controlling the motor current.

The stretching and contraction of cable 15 is automatically compensated for by having the cable pass over the pulley 22 of safety switch 16 and held taut by a freely suspend ed weight. The drum in being moved to its normal position by the pull of the weight is always stopped in a definite position by arm 26 engaging stop 25. The weight, exerating a constant pull. on the cable, thus maintains a constant tension on the cable, which"v slips on pulley 22 just enough to be kept taut. The lengthening or shortening of thc cable, therefore, has no injurious effect upon the operation of the safety switch.

The violent or repeated opening of the door might, because of the momentum of the drum switch, cause the cable to slip over pulley 22 far enough in the reverse direction to prevent the subsequent interconnection of contacts 29 and contacts 80 when the door is closed. This would prevent the operation of the elevator even though the door was shut. Such a con'ditionis obviated by providing the stop 24 in such a. position that it is engaged by arm 26 upon a small movement of the drum caused by a slight opening of the door. During the remainder of the flexing of the cable caused by the completion of the opening of the door the cable slips on pulley 22. Whenever the door is closed there is, therefore, enough movement of the cable to insure that arm 26 will engage stop 25, in which position contacts 29 and contacts 30 are interconnected and the elevator may be started. By' the proper spacing of stops 2e and 25 the correct positioning of the interconnecting contact- s 27 and 28 is insured for both the. open and closed conditions of the door. 1t has been found that satisfactory results can be obtained by having the stops comparatively close together and arranging the contacts so that interconnection and disconnection are accomplished by a slight rotation of pulley 22. The desired friction of cable 15 upon pulley 22, to insure proper operation of the drum safetyswitch and not to render the movement of the door difficult, can be obtained by making the pulley 21 adjustable in an upward and downward direction so that the amount of the circumference of pulley" 22 engaged by the cable can be increased or decreased.

1n case cable 15 should break while the door is closed, a counter-weight moves the drum of safety switch 16 in the direction of the arrow, breaking the connections between contacts 29 and contacts 30. Master switch 10 is, thereupon denergized and the car cannot be operated until the cable is repaired. if the cable breaks while the car isrunning, it is immediately stopped. 1n case the break occurs while the door is open, and consequently the connections between contacts 29 and 30 are already broken, counter-weight 85 holds the drum of safety switch 16 in that position. The master switch cannot be closed and the elevator cannotbe started. @ther means than a counterweight may be used to rotate the drum of safety switch 16 when the cable breaks. For example, a spring acting in opposition to weight 23 may be employed. y, Y

While the invention has been described in connection with one type of electrical elevator equipment, it will be readily understood that it may be employed with other types and that its use is not confined to electrically operated elevators.

The shaft and car doors may be suitably interloclred, so that both must be closed before the elevator can be operated. One form of interlock is disclosed in my Patent No. 1,293,688, granted Feb. 11, 1919.

The invention claimed is:

1. rin elevator control having a source of power for raising and lowering the elevator car, an electromagnetic's'witch for controlling said source in raising' the car, an electromagnetic switch for' controlling said source in lowering the car, means actuated by the car operator for controlling both said electromagnetic switches, a safety switch for causing' the operation of either electromagnetic switch to prevent further movement of the" car independentlyV of said means, and

a member extending along the elevator shaft and operable by the movement of the car door in any position of the car to control said safety switch.

2. in elevator control comprising a masswitch for controlling the application of power' to the elevator car, a safety switch for controlling said master switch, and a cable extendingalong the elevator shaft and operated by the car door for controlling said safety switch, whereby the application of power to the elevator is under the control ofthe door thereof( Y il. in elevator control comprising an electromagnetic master switch for controlling the application of power to the elevator motor, safety mechanism under the influence of the elevator door for controlling said master switch, and means dependent upon theV operating conditions of the elevator motor for modifying they control of said safety mechaiism over said master switch.

a. Aln elevator control comprising an electromagnetic master switch for controlling the application of power to the elevator, acceleration control means for governing the speed of the elevator, safety mechanism under the influence of the elevator door for controlling said master switch, and means associated with said acceleration control means for modifying the control of said safety mechanism over said master switch.

An elevator control having mechanism for raising and lowering the elevator car, a 1able extending along the elevator shaft and actuated by the car door for controlling said mechanism, and means for automatically compensating for stretching or contraction of said cable'.

.6. An elevator control having mechanism for operating the elevator car, a cable extending along the elevator shaft and actuated by the car door for controlling said mechanism, and means for automatically maintaining the operative relation between said cable and said mechanism.

'7. A control for elevator operating means comprising a cable extending along the elevator shaft and under the control of the car door, safety mechanism controlled by said cable for preventing the operating means from moving the car when the door thereof is open, and means for causing said safety mechanism to prevent movement of the elevator if the cable breaks.

8. An elevator control having mechanism for raising and lowering the elevator car, a fiexible cable fixed at one end and extending along the elevator shaft and controlled by the open and closed condition of the car door, a safety switch including a rotatable member for controlling said mechanism, said rotatable member being controlled by said cable, and a weight connected with the free end of the cable for automatically compensating for stretching or contraction of said cable.

9. An elevator control having mechanism for raising and lowering the elevator car, a iiexible cable extending along the elevator shaft and controlled by the open and closed condition of the car door, a safety switch, including a rotatable member, for controlling said mechanism, said rotatable member being controlled by said cable, means for limiting the movement of the rotatable member in either direction, and means associated with the cable and coperating with said limiting means for automatically maintaining the operative relation between the cable and said safety switch.

10. An elevator control having mechanism for raising and lowering the elevator car, a fiexible cable extending along the elevator shaft and actuated by the car door, a safety switch controlled by said cable and controlling said mechanism, said safety switch including a rotatable Contact carrying drum engaged by said cable.

ll. A control for elevator operating means comprising a cable extending along the car shaft and under the control of the car door, safety mechanism including a switch mounted on a drum and controlled by said cable for causing the operating means to stop the car when the car door is opened, and a weight cooperating with the drum to cause the switch to open if the cable breaks.

l2. A control for elevator operating moans comprising a cable extending along the car shaft and under the control of the car door, a switch controlled by said cable to cause the operating means to stop the car at any point of the shaft if the door is opened, said switch comprising a drum, contacts thereon, stops to limit the movement of the drum in each direction, and means for varying the arc of contact of the cable with the drum to permit the cable to freely slide over said drum after engaging a stop.

In witness whereof I have hereunto subscribed my name.

EDWIN F. BANFIELD.

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