US2308211A

US2308211A - Elevator control mechanism

Info

Publication number: US2308211A
Application number: US439783A
Authority: US
Inventors: Sanford Selden Bradley
Original assignee: Otis Elevator Co
Current assignee: Otis Elevator Co
Priority date: 1942-04-20
Filing date: 1942-04-20
Publication date: 1943-01-12
Anticipated expiration: 1960-01-12

Description

Jan. 12, 1943. s. B. SANFORD 2,308,211

ELEVATOR CONTROL MECHANISM Filed April 20, 1942 4 Sheets-Sheet l Yl m m w W o N m 0 /T M w Q Ru QbQQ 0. n v' 6 m Q Q w m 4 M IHWUMU. R 7. 7. S W. mm CT. m m

Q E T w Fm 1& m E gm. m. m mu m AV" L T WNW E n H.. H M w u MN TP ,m L M N 0% H M fl R m C R m B T E 5D R W ADH -hw, R A /nMU w mm m m f v w I I w m FIU .M W R m s w w Ell w mm m m & MN MW W M I m Jan. 12, 1943. s. B. SANFORD ELEVATOR CONTROL MECHANISM Filed April 20, 1942 4 Sheets-Sheet 2 9 u n 9 2 w N. Q g a 8 m E w o 0 on 8 m l m W .HLLJ R n w NW W "0 Q w Y /T 8 Q PS I E E. .l a E. 5 a n 2 8 S 3% R m N E V m S 6 E N R 0 w A Jan. 12, 1943. s. B. SANFORD ELEVATOR CONTROL MECHANISM Filed April 20, 1942 4 Sheets-Sheet 4 IND LM 0A I I I I I I I I I I I I I I I I I o L i II T- ui mw fiI w IIIIIIIIIIIIIII Kv s w Rw III III III I KI QT IIIIIII I I I I I III w IIIIIIIIIIIIIIII IIIIIIQIIIIIIIIIIIIIIIIIIIIIIDflMg ATTORNEY Patented Jan. 12, 1943 ELEVATOR CONTROL MECHANISM Selden Bradley Sanford, Yonkers, N. Y., assignor to Otis Elevator Company, New York, N. Y., a corporation of New Jersey Application April 20, 1942, Serial No. 439,783

10 Claims.

operation of an elevator car so as to obtain accurate stops at the landings.

There are various factors which afiect the accuracy of stopping of an elevator car. One or the principal factors is the load carried. by the car. Assuming a constant retarding force, the car speed will be reduced to a given low speed in less distance when the elevator motor is lifting a heavy load than when it is lowering a heavy load. Various arrangements have been provided for compensating for this effect. Among these are weighing devices carried by the car connected to register the load suspended on the hoisting ropes and arranged to utilize the measurement thus obtained to vary the point of initiation of 7 the stopping operation. The invention is directed to mechanism of this character.

The object of the invention is to provide an improved load weighing device carried by the elevator car for varying the distance for bringing the car to a stop at a floor.

In carrying out the invention according to the arrangement which will be described, resilient means is provided between the hoisting ropes and. the car framework. The load on the car is measured by the compression of the resilient means under different loads. The amount of this compression is amplified by lever mechaping operation. These cooperating means are preferably in the form of an inductor switch carried by the end of the lever mechanism and inductor plates in the hatchway for the various landings. Mechanism is associated with the lever mechanism near the end thereof for holding the end of the lever mechanism in position after the load is measured to obviate any inaccuracies such as those due to inertia or friction. The lever mechanism is made flexible to allow for any strain during operation due to the end of the lever mechanism being held.

A general idea of the invention and the various features and advantages thereof will be gained from the above statements. Other features and advantages of the invention will be apparent from the following description and appended claims.

In the drawings:

Figure 1 is a simplified schematic representa The present invention relates to controlling the vi tion of an elevator installation embodying the invention;

Figure 2 is a top view of a somewhat schematic representation of the load weighing device of Figure 1;

Figure 3 is a side view of the same with parts in section;

Figure 4 is a detail taken along the line 44 of Figure 3;

Figure 5 is a detail of resilient means employed between the ends of the hoisting ropes and the carframe;

Figure 6 is a simplified wiring diagram of an elevator control system chosen to illustrate an application of the invention; and

Figure 6.9 is a key sheet for Figure 6 showing the electromagnetic switches in spindle form with the contacts and coils arranged on the spindles in horizontal alignment with the corresponding contacts and coils in the wiring diagram.

The invention is of particular application to a slow speed elevator installation, say of one hundred to one hundred and fifty feet per minute car speed, in which a polyphase alternating current motor is employed to raise and lower the car. In such installations it is usual to slow down and stop the car simply by disconnecting supply of power to the hoisting motor and applying the electromechanical brake. Inasmuch as this provides the same retarding force for all loads, the

amount of coast of the car before it is brought to rest is greatest with full load down and least with full load up. The load weighing device acts to provide accurate stops by initiating the slow down at distances from the floor corresponding to the coast of the car for the particular load conditions and in view of its particular adaptability to installations of this nature and the relative simplicity of control systems for these installations, the invention will be described as applied to an elevator system of this character.

For a general understanding of the invention,

7 reference may be had to Figure 1 wherein various parts of the system chosen to illustrate the principles of the invention are indicated by legend. The car is raised and lowered by means of the hoisting motor which drives a traction sheave over which pass the hoisting ropes for the car and counterweight. An electromechanical brake is provided for stopping the'car and holding the car when at rest. The invention is illustrated as applied to a system in which the operation of the car is controlled by the passengers and intending passengers themselves by pressing hall buttons at the landings and car buttons in the tween lock nuts 18 and the hitch plate.

car. These push buttons act through floor relays, these relays and the electromagnetic control switches utilized in this system being arranged on the control panel. In such systems mechanism actuated in accordance with car movement is utilized. This mechanism is illustrated as in the form of a selector machine driven by a tape having teeth formed thereon for actuating a sprocket driving wheel for the selector machine. The tape is connected at one end to the top of the elevator car, passes over the sprocket wheel and is connected at the otherend to the counterweight. The selector machine comprises a crosshead which is driven by a screw, which in turn is driven by the sprocket wheel to move the crosshead in accordance with movement of the car. The crosshead carries brushes for cooperating with stationary contacts to pick up calls for the floors at which push buttons have been pressed. When a call is picked up this renders an inductor switch carried by the car efiective to initiate the stopping operation. Inductor plates are provided in the hatchway for the various landings and, as the car arrives at a certain distance from the landing at which the call has been picked up, the inductor switch moves into cooperation with the plate for that landing for the direction of car travel to initiate the stopping operation.

The distance of the car from the landing at which the inductor cooperates with the inductor plate is determined by the load weighing mechanism. The load weighing mechanism comprises a resilient connection between the ends of the hoisting ropes and the car framework, the amount of compression of which is measured by a movable rod. The movement of this rod is amplified by a pair of levers pivoted on the car framework. The inductor switch is mounted on the outer end of the outer lever. A locking device comprising a rack mounted on the outer lever adjacent the inductor switch and a magnetically actuated pawl mounted on the car framework in position to engage the rack to hold the inductor switch in position corresponding'to the load carried by the car.

For a further discussion of the load weighing mechanism, reference may be had to Figures 2, 3, 4 and 5. While these figures are still somewhat schematic, they are on a much larger scale and give a more comprehensive idea of the operation of the mechanism. An installation having four hoisting ropes is illustrated. Each hoisting rope It] is connected to the car framework through a thimble rod II. A plate I2 is provided beneath the top cross channels I3 of the car framework. This plate is secured to the cross channels by bolts l4. Below this plate is a hitch plate l5, the plate i2 being of the same size as the hitch plate. A rubber pad I6 is arranged between these plates. The thimble rods pass through aligned apertures in the platesand rubber pad. Compression springs H are provided on the lower ends of the thimble' rods be- This arrangement is utilized to enable adjustment of the tension of the ropes. Washers 20 are provided on each rod at each end of the spring. The apertures through the plates and rubber pad are made considerably larger than the thimble rods 'to obviate any possibility of binding.

The upper washer 29 on each thimble rod is formed with a shoulder to fit into the aperture in the hitch plate to maintain the thimble rod central withrespect to the aperture at this point.

The rubber pad is located with respect to the plates [2 and I5 by means of pockets 2| in the pad into which the heads of bolts l4 and lugs 22 on plate l5 extend. The construction and properties of the pad are such as to support the car without undue transmission of vibrations thereto and to give a certain amount of overall compression when the load in the car is increased from nothing to full load. In this connection, holes 23 are provided in the pad to provide a certain ratio of effective area to bulge area, with the effective area greater than the square of the thickness.

The pad is also provided with a central aperture 24 aligned with an aperture 25 in plate [2.

These apertures are for receiving a load measuring rod 26 which rests at its lower end on the top of hitch plate l5. As the load in the car increases and compresses the pad, this rod is pushed upwardly with respect to the car framework by the hitch plate 15. This provides a movement which is proportional to the change in load in the car. This movement is transmitted to the inductor switch by a system of le- Vers whereby amplification is obtained in an amount to provide the desired range of variation of slow down distances for the particular installation. This systemof levers comprises a lever 21 pivotally connected at one end to rod 26 and mounted on a fulcrum 28 secured to plate I 2. The outer end of lever 21 is connected by a link 30 to the inner end of a lever 3| mounted on a fulcrum 32 secured to the top of channels [3. The outer end of lever 3i is connected by a link 33 to the inner end of a lever 34. This latter lever is mounted on a fulcrum 35 secured to the top of channels E3. The inductor switch 36 is mounted on the outer end of lever 34. Levers 3| and 34 are amplifying levers, two levers being utilized instead of one to increase the ampliflcation ratio. Lever 21 is utilized to obtain the proper direction of movement of lever 34. A twenty-five to one amplification is readily obtained with this lever system so that, with a pad which compresses one quarter inch from no load to full load, six and a quarter inches of movement of the inductor switch is provided which is suitable for an installation of 2000 pounds at feet per minute.

Lever 33 comprises two offset arms [9 and 29 operably connected by a cross shaft 31, this arrangement being utilized to avoid the guides 39 for the car. The arm [9 comprises two spaced members 38 and All to enable the link 33 to be adjustably connected thereto and thus permit adjustment of the lever ratio. This adjustable connection is provided by forming the link of two spaced members M and 42 and connecting the upper ends of these members to a pin 43 slidable in slots 44 in the members 38 and MB. A block 45 is arranged on the pin between

members

38 and 40 and has a threaded stud 43 secured thereto. This stud slidably extends through an aperture in the yoke il connecting the inner ends of members 33 and til. Adjusting nuts 48 on the stud are turned to shift the pin in the slots to thereby change the lever ratio.

The inductor switch 36 is secured to the end of lever 34 by a bracket 53; This switch may be of the construction shown in application of Lewis et al., Number 2,101,146 granted December 1'7, 1937. It comprises a frame 5| having two magnetizable plates 52 and 53 extending therefrom between which is positioned an el'ectromag'net 54. The plates extend beyond the magnet to form a pocket to receive the hatchway plates 55. An armature 56 is pivotally mounted on a bracket 51 secured to plate 52. When the plates 52 and 53 come opposite a hatchway plate under conditions where the electromagnet is energized, the armature is pulled inwardly against the force of a spring 58 into a slot in the end of plate 52. When this takes place a movable contact carried by the armature disengages thestationary contact on the frame to initiate the stopping operation, these contacts being designated 60. The hatchway plates are secured to the hatchway wall by brackets 6|. iwo plates are provided for each intermediate landing as indicated in Figure 1, the lower for initiating stopping of the car during up car travel and the upper for initiating stopping of the car when the car is travelling in the down direction. These plates are positioned to provide accurate stopping of the car, preferably being set for the most prevailing load conditions, which in many installations is two or three passengers.

The locking device for holding the inductor switch in load registering position comprises a segmental toothed rack 66 secured by a bracket 84 to the outer end of lever 34 adjacent the inductor switch. This rack is adapted to be engaged by a pawl 65 actuated by an electromagnet 52 arranged in a frame 63 mounted on a bracket 6'! secured to the top of the cross channels 3. This pawl 65 in the form of a bell crank is pivotally mounted on the frame 63. The pawl is biased by a spring 68 into position disengaging the rack. The electromagnet is provided with a plunger E which is adapted to pull the pawl against the force of the spring into engagement with the rack. The electromagnet 62 is energized to actuate the pawl into engagement with the rack after the load has been weighed, thus locking the end of lever 34 and thus the inductor switch in load registering position. The bracket 61 is formed with a vertical slot 69 into which lever 34 extends to form a guide to insure the proper positioning of the inductor switch with respect to the inductor plates.

A weight H is adjustably mounted on the outer end of lever 3| for balancing the weight of the inductor switch and locking device carried by the outer end of lever 34, the arms of the levers being chosen so as to place the system otherwise substantially in a state of balance. A spring 12 is connected between the outer end of lever 3| and a clip 13 secured to the cross channels for insuring the measuring rod being in position against hitch plate during the weighing operation. To obviate any undue stress or breakage when the outer end of the lever 34 is locked, due for example to the inertia of the car during the stopping operation, the lever system is made flexible. This may be done for example by providing a toggle joint 74 in lever 3| to permit downward movement of the inner end of this lever should the car move upwardly with respect to the cross channels when lever 34 is locked in position. To form this toggle joint, lever 3| is made in two sections, one designated 15 and the other formed of two side members 16 and I! straddling the end of section 1.5. A stop plate 18 secured to the inner end of the side members 16 and I7 extends inwardly over the outer end of section 15. A stud 80 extends upwardly from the outer end of section 15 through an aperture in the stop plate and a compression spring 8| is arranged on this stud between the stop plate and a washer secured to the end of the stud. This arrangement effectively transmits the movement of lever 3| to lever 34 but is yieldable to enable the toggle to be broken upwardly in the event of upward movement of the car relative to the cross channels when lever 34 is locked. In case of relative movement of the car downward with respect to the cross channels when lever 34 is locked the hitch plate simply disengages the end of the rod.

When the car is empty the mechanism is in the position illustrated in Figure 3. As passengers enter the car, the car moves downwardly acting through plate |2 to compress the rubber pad. This causes upward movement of rod 26 relative to the car framework swinging lever 21 clockwise about its pivot. This causes counterclockwise movement of lever 3| which in turn causes clockwise movement of lever 34 to move the inductor switch downwardly relative to the car. When the car becomes fully loaded the inductor switch and lever 34 assume the positions indicated in dot-dash lines in Figure 3. The magnet 62 is energized to move the pawl 65 into engagement with the rack 66 to lock lever 34 in position after the load weighing has been completed. Assuming that the car is moving upwardly, as it approaches a floor at which a stop is to be made, the inductor switch comes opposite the up inductor plate for that floor to open the inductor switch contacts. The distance of the car from the floor when this occurs is smaller the greater the load on the car owing to the fact that the greater the load the farther lever 34 has been swung clockwise and therefore the closer the car will be to the floor when the inductor switch comes into cooperation with the plate. Should the car have been started in the down direction, upon its approaching a floor at which a stop is to be made, the inductor switch comes opposite the down inductor plate for that floor to open the inductor switch contacts. The distance of the car from the floor when this occurs is greater the greater the load on the car owing to the fact that the greater the load the farther the lever 34 has been swung clockwise and therefore the farther the car will be from the floor when the inductor switch comes into cooperation with the plate. Thus the mechanism acts to effectively compensate for the load on the car by varying the distance from the floor at which the stopping operation is initiated in such a way as to cause the car to be brought to a stop at the landing. Inasmuch as the lever arm 34 is locked after the load is weighed, proper position of the inductor switch with respect to the car for the stop initiating operation is assured. The lock magnet is deenergized to release the inductor switch after the stopping operation has been initiated so that the load may be reweighed for the next stopping operation.

Reference may now be had to Figure 6 which.

illustrates diagrammatically the control and power circuits of a push button elevator system embodying the invention. The circuits are shown in straight or across-the-line form, in which the coils and contacts of the various switches are separated in such manner as to render the circuits as simple and direct as possible. The relationship of these coils and contacts may be seen from Figure 6s wherein the switches are arranged in alphabetical order and shown in spindle form. The positions of these coils and contacts in the wiring diagram may be found by referring to Figure 6s, where the coils and contacts are positioned on the spindles in horizontal alignment with the corresponding elements of the Wiring diagram.

The circuits for a four floor installation are illustrated. The car buttons are designated CI, C2, C3 and C4 for the first, second, third and fourth fioors respectively. The car buttons act through fioor relays designated IC, 20, 3C and 4C for the first, second, third and fourth floors respectively. Where the first floor is the basement and the second floor is the main floor, both an up hall button and a down hall button are provided at the main floor in the particular control system illustrated. Assuming that this is the case, these buttons are shown and are designated U2 and D2 for the up and down hall buttons respectively. These buttons respectively act through floor relays designated 2U and 2D. Single hall buttons are provided at each of the other floors, the hall button at the first fioor (basement) being designated UI, the hall button at the third floor being designated D3 and the hall button at the fourth floor being designated D4. These hall buttons act respectively through floor relays designated IU, 3D and 4D. Each of the floor relays is of the latching type and has an operating coil and a reset coil, the operating coils being in series with the respective push buttons and the reset coils being controlled by the selector.

The floor relays act in conjunction with direction determining mechanism on the selector to determine the direction of travel of the car. This direction determining mechanism comprises a plurality of director switches designated I41, I42, I43 and I44 for the first, second, third and fourth floors respectively. The director switches are stationary and are spaced in accordance with the distance between the corresponding floors. These switches are engaged by a direction cam arranged in three sections designated I45, I46 and I41, I45 being a down section, I45 a neutral insulated section, and I41 an up section. The floor relays also act to render the stationary contacts on the selector machine alive to be engaged by brushes carried by the selector crosshead to pick up the calls that are registered. These stationary contacts are arranged in three columns. The stationary contacts in the first column are designated III, H2 and H3 for the first, second and third fioors respectively and are respectively controlled by floor relays IU, 2D and 3D. The stationary contacts in the second column are designated I22 and I24 for the second and fourth floors respectively and are respectively controlled by

floor relays

2U and 4D. The stationary contacts in the third column are designated I3I, I32, I33 and I34 for the first, second, third and fourth floors respectively and are respectively controlled by floor relays IC, 2C, 30 and 4C. Stationary contacts I I I, H2 and I I3 are engaged by down call pick up brush [I .and

reset brush H6, the reset brush engaging the stationary contacts when the car is stopped at the respective floors, while the call pick up brush H5 is advanced ahead of the reset brush a distance greater than stop initiating distance. Stationary contacts I22 and I24 are engaged by up call pick up brush I2! and reset brush I26, the reset brush engaging the stationary contacts when the car is stopped at the respective floors, while the call pickup brush I21 is advanced ahead of the reset brush a .distance greater than stop initiating distance. Stationary contacts I3I, I32, I33 and I 34 are engaged by down call pick up brush I35, up call pick up brush I31 and 'reset brush I36, the reset brush engaging the stationary contacts when the car is stopped at the respective floors, while the call pick up brushes I35 and I3! are advanced ahead of the reset brush in the corresponding directions of car travel a distance greater than stop initiating distance.

The alternating current supply mains are designated I, II and III. SK indicates a triple pole knife switch controlling the connection of the power mains to the system. The hoisting motor is illustrated as of the squirrel cage induction type, the rotor being designated I50 and the stator windings I5I, I52 and I53. Resistances I54, I55 and I56 are connected in series with the stator windings for controlling the torque of the motor. The electromechanical brake is designated BR. EXA designates the armature, EXF the shunt field winding and EXS the series field winding of an exciter for supplying certain of the control circuits. This exciter is driven by a polyphase alternating current motor, the rotor of which is designated I5! and the stator windings I58, I59 and I60.

While the hatchway doors in the system illustrated are manually opened and automatically closed, the car gate is power operated, for example by mechanism such as that schematically illustrated in the aforesaid Lewis et a1. Patent No. 2,101,146. I62 designates the rotor of the polyphase alternating current operating motor of such mechanism. The stator windings of this motor are designated I63, I64 and IE5. GOL is a gate open limit switch for controlling the operation of the gate operating motor. The gate contacts closed when the gate is closed are-designated GS. The auxiliary door contacts closed when the hatchway doors are closed are designated collectively ADS. The door interlock contacts closed only when the respective hatchway doors are closed and locked are designated collectively DS. ES is the emergency stop switch in the car. Other safety devices are grouped and are indicated by the legend safeties.

The electromagnetic switches employed in the system are designated as follows:

Throughout the description which follows these letters will be applied to the coils of the above designated switches. Also, with reference numerals appended thereto, they will be applied to the contacts of these switches. Relay S is a latching relay having both an operating coil and a reset coil. The inductor electromagnet 54 has its coil designated IND in the wiring diagram with the numeral 54 added in brackets, whereas the contacts 60 of the inductor are designated CX DL INDI in the wiring diagram with the numeral 60 added in brackets. The electromagnet 62 of the locking device has its coil designated LM in the wiring diagram with the numeral 62 added in brackets. The electromagnetic switches and the inductor switch are illustrated in deenergized condition while the latching relays are illustrated in reset condition.

Assume that the car is standing idle at the second floor (main floor). The floor control circuits are illustrated in Figure 6 in accordance with this assumption. As the car is idle, the second floor hatchway door is closed but not locked and the car gate is open. Door lock contacts DS for the second floor and gate contacts GS are therefore open. The auxiliary door contacts ADS, however, ar closed.

Assume now that an intending passenger at the third floor presses hall button D3. This connects operating coil 3D of the corresponding floor relay across two phases of the alternating current supply mains to operate the floor relay. The floor relay is latched in operated condition permitting the push button to be released. The floor relay engages contacts 3DI, 3D2 and 3D3. The engagement of contact 3DI connects the coil of exciter set starting switch ST across the alternating current supply lines causing this switch to operate. Upon operation, relay ST engages contacts STI, STZ and ST3 to connect the stator windings of the exciter set driving motor to the alternating current supply mains, bringing the exciter set into operation.

As the exciter voltage rises to a certain value, door relay operates to engage contacts OI which completes the circuit for the coil of time relay Z. Relay Z does not operate immediately contacts OI engage, being delayed as by a dash pot. Upon the expiration of this time interval contacts ZI and contacts Z2 engage. The engagement of contacts ZI completes the circuit for the coil of up reversing switch relay AU, this circuit being through interlock contacts EDI and B4, terminal stopping switch contacts I16, direction cam up section I41, third floor director switch hi3, floor relay contacts 3D3, resistance I13, and contacts ZI. Relay AU upon operation separates interlock contacts AUI to render down call pick up brush II5 ineffective and separates interlock contacts AUZ in the circuit for the coil of relay BD. It also engages contacts AU4 to prepare the circuit for the coils of up reversing switch A and potential switch C. It also engages contacts AU3 to complete a circuit for the coil of reversing switch relay AB. Relay AB upon operation engages contacts ABI by-passing time relay contacts ZI. It also engages contacts AB3 to complete a circuit through contacts SS2 for the operating coil of call pick up relay S. Relay S latches itself in operated condition, engaging contacts SI and contacts S3 and separating contacts S2.

Contacts SI of the call pick up relay complete a circuit for the coil of gate relay DL and the coil LM of the locking device magnet through contacts AB3. The locking device acts to lock the load weighing device in position. Under the assumed conditions, no one is in the car so that the inductor switch is locked in its uppermost position shown in full lines in Figure 3. Relay DL engages contacts DLI and DL2 and separates contacts DL3. The engagement of contacts DLI is without effect because contacts AB2 are separated. The engagement of contacts DL2 cornpletes a circuit for the coil of gate close switch GC. v

Gate close switch GC upon operation engages contacts GCI, G02 and GC3 to complete a circuit through portions of resistances Ill and I18 for the stator windings I63, I64 and IE5 of the gate operating motor for a phase rotation of the applied voltage to cause the closing of the car gate. As the gate starts to close, gate open limit switch GOL closes to complete the circuit for the coil of auxiliary exciter relay G, the circuit for the coil of gate open switch GO being open at contacts DL3 and GC4. Relay G engages contacts G! in circuit for the coil of relay ST and separates contacts G2 in circuit for the reset brushes IIS, I26 and I36 of th selector. As the gate reaches closed position the retiring cam is retired to lock the second floor hatchway door and close the door lock contacts DS thereof and the gate contacts GS close, completing a circuit for the coils of potential switch 0 and up reversing switch A. This circuit is through terminal stopping switch I8D, contacts AU4, S3 and INDI, door lock contacts DS, gate contacts GS and emergency stop switch ES.

The up reversing switch upon operation engages contacts A5 to establish a self-holding circuit and separates interlock contacts A4 in circuit for the coil of relay BD. Potential switch C upon operation engages contacts CI and C2 which together with the engagement of contacts AI and A2 of the up reversing switch completes a circuit for the stator windings I5I, I52 and I53 of the elevator hoisting motor for a phase rotation of the applied voltage to move the car in the up direction. At the same time'switch C engages contacts C3 and C4 and switch A engages contacts A3 to complete a circuit for the brake release coil BR to release the electro-mechanical brake and the car starts in the up direction. The brake in releasing opens brake switch BRI to insert cooling resistance I82 in circuit with the brake coil. Contacts A3 and C4 also complete a circuit for the coil of auxiliary potential switch relay CX which operates to engage contacts OK I and OX2.

Contacts CXI by-pass contacts SI and AB3 in circuit for the coil of gate relay DL. Contacts OX2 are in circuit for the coil of the inductor switch IND, this circuit being now open at contacts S2. Contacts A3 and C4 also complete a circuit for the coil of accelerating switch K. Switch K operates to engage contacts KI and K2 to short-circuit resistance I54, I55 and I 58 to apply full line potential to the stator windings of the hoisting motor, the operation of switch K bein delayed as by a dash pot.

Switch K also engages contacts K3 to complete the circuit for the coil of auxiliary time relay SS. Relay SS operates to engage contacts SSI establishing a self-holding circuit. It also sepa rates contacts SS2 in the circuit for the coil of call pick up relay S. Switch K also separates contacts K4 which deenergizes time relay Z. Relay Z drops out to separate contacts Z2 which with the separation of contacts SS2 deenergizes the operating coil of relay S. Relay S remains operated, however, since as previously pointed out it is latched in operated condition. Relay Z also separates contacts ZI3 this being without effect, however, as contacts ABI are engaged.

As the car approaches the third floor the upper section ll! of the direction cam runs off the third floor director switch I43 which breaks the circuit for the coil of up reversing switch relay AU. The resultant separation of contacts AU4 is without effect as these contacts are lay-passed by contacts A5. The separation of contacts AU3 breaks the circuit for the coil of auxiliary re versing switch relay AB. Relay AB drops out to separate contacts AB3 but this is without effect as the circuit for the operating coil of relay S is already broken at contacts Z2 and SS2 and as contacts CXI maintain the circuit for locking device coil LM and the coil of relay DL. AB also engages contacts AB2 which completes a circuit through contacts DLI for the reset coil of call pick up relay S. This picks up the call for the third floor. The energization of the reset coil of relay S causes this relay to be reset, resulting in the separation of contacts SI, S3 and the engagement of contacts S2. The separation of contacts SI is without effect as these contacts are bypassed by contacts CXI. Also the separation of contacts S3 is without effect as these contacts are Icy-passed by contacts A5.

The reengagement of contacts S2 completes the circuit for the coil IND of the inductor switch through contacts 0X2. This renders the inductor switch effective for cooperation with the up inductor plate in the hatchway for the third floor. As th inductor switch comes opposite this plate it separates the inductor switch contacts INDI. Under the assumed conditions this occurs at maximum stopping distance for upward car travel for the third floor owing to the fact that as the car is empty the maximum amount of unbalanced weight of the counterweight acts as an overhauling load to oppose the stopping operation. The separation of the inductor switch contacts breaks the circuit for the coils of up reversing switch A and potential switch C. The resultant separation of contacts CI, C2, AI and A2 breaks the circuit for the elevator hoisting motor. The separation of contacts A3, C3 and C4 breaks the circuit for the brake release coil to apply the brake thereby to slow down the car and bring it to a stop at the third floor.

The separation of contacts A3 and C4 also break the circuit for the coils of auxiliary potential switch relay CX and accelerating switch K. Switch K in dropping out reengages contacts K4 to complete the circuit for the coil of time relay Z. The time relay Z, as pointed out above, is delayed in operating so that contacts 2! and Z2 remain separated. However, this does start the timing operation provided by relay Z. Relay OK in dropping out separates contacts CXI to break the circuit for coil LM of the locking device magnet while the separation of contacts OX2 breaks the circuit for the coil IND of the inductor switch, these parts having performed their function in the stopping operation. The separation of contacts CXI also breaks the circuit for the coil of gate relay DL which in dropping out separates contacts DLI to deenergize the reset coil of relay S and separates contacts DLZ to deenergize the coil of gate close switch GC. The gate close switch in dropping out separates contacts GCI, G02 and GC3 to deenergize the gate operating motor. It also reengages contacts GC4 which together with the reengagement of contacts DL3 as a result of the dropping out of relay DL completes the circuit for the coil of gate open switch GO.

Gate open switch GO upon operation engages contacts GOI, G02 and G03 to complete a circuit through other portions of resistances Ill and I18 for the stator windings I63, I34 and I65 of the gate operating motor for a phase rotation of the applied voltage to cause the opening of the car gate. The gate open switch also separates contacts G04 to break the circuit for the coil of time relay Z. This relay drops out imthat door.

mediately, cancelling the timing operation. As the gate starts to open the retiring cam is extended to unlock the third floor hatchway door, causing the opening of door lock contacts DS for Also gate contacts GS open. As the gate reaches open position, gate open limit switch GOL opens to deenergize the gate open switch G0 which drops out to separate contacts GOI, G02 and G03, breaking the circuit for the gate operating motor. Also the opening of gate open limit switch GOL breaks the circuit for the coil of auxiliary exciter relay G.

As the car comes into the floor the insulated section Hi6 of the direction cam runs onto the third floor director switch I43 isolating the third floor direction and control circuits. Also the reset brushes move into engagement with the third floor stationary contacts. The engagement of contacts G2 as the result of the deenergization of relay G establishes a circuit through resistance I83, brush H3, stationary contact H3 and floor relay contacts 3D2 for the reset coil of the third floor relay 3D. This causes this relay to be reset. Also the separation of contacts GI and contacts 3DI breaks the circuit for the coil of exciter set starting switch ST which drops out to separate contacts STI, STZ and 6T3. This breaks the circuit for the stator windings of the eXci-ter driving motor which shuts down the exciter set.

The door being unlocked the intended passenger may open the door and enter the car. Assume that he wishes to go to the first floor and presses car button CI. This causes the operation of the corresponding floor relay IC which is latched in operated condition, permitting the push button to be released. The relay operates as previously described for floor relay 3D to start the exciter set in operation and as the exciter voltage rises to a certain value it causes the operation of the auxiliary reversing switch relay. In this case down relay ED is operated, the circuit being through the coil of relay BD, contacts AUZ and A4, terminal stopping switch contacts I15, direction cam down section I45, second and first floor director switches I42 and IM and floor relay contacts ICE. Relay BD engages contacts BD3 to cause the operation of relay AB which in turn causes the operation of relay S. Relay S engages contacts SI which, assuming that the 'thid floor door has closed so that relay 0 is operated, completes a circuit for coil LM of the locking device magnet. This looks the weighing device in load weighing position. In this position the lever 34 is swung slightly clockwise from the position illustrated in full lines in Figure 3, as a passenger is in the car.

Relay DL upon operation causes the operation of gate close switch G0 which in turn causes the closing of the car gate and the locking of third floor hatchway door. The resultant closing or the hatchway door lock contacts completes a circuit for the coil of potential switch C and the coil of down reversing switch B through contacts BD4. Switches B and C engage contacts CI, C2, C3, C4, BI, B2 and B3 to complete the circuits for the stator windings of the elevator hoisting motor and for the brake release coil to cause the starting of the car, the car being started in the down direction owing to the fact that down reversing switch contacts BI and B2 establish a phase rotation of the voltage applied tothe stator windings for down car travel. Contacts B3 and C4 also complete the circuit for the coils of relay CX and switch K. Switch K acts to short circuit the resistance in circuit with the stator windings of the hoisting motor. It also completes the circuit for the coil of relay SS and breaks the circuit for the coil of time relay Z.

Assume that before the car arrives at call pick up distance from the second floor an intending passenger at that floor presses down button D2. This causes the operation of the corresponding floor relay 2D which engages contacts 2D2 to render stationary contact H2 alive. Upon engagement of this contact by brush H5 a circuit is completed for the reset coil of call pick up relay S. This picks up the call for the second floor and resets the call pick up relay. The reengagement of contacts S2 completes the circuit for the coil IND of the inductor switch. As the inductor switch comes opposite the down plate for the second floor, its contacts INDI are separated. Under the assumed conditions this occurs at a distance somewhat greater than minimum stopping distance for downward car travel for the second floor owing to the fact that as a passenger is in the car, less than the full unbalanced weight of the counterweight is being lifted so that slightly more than this minimum stopping distance is required for the brake to stop the car. The separation of inductor switch contacts INDI breaks the circuit for the coils of down reversing switch B and potential switch 0. These switches drop out to break the circuit for the elevator hoisting motor and for the brake release coil and the brake is applied to slow down the car and bring it to a stop at the second floor. Coil LM of the locking device magnet and coil IND of the inductor switch are deenergized by the separation of contacts CXI and OX2 respectively as a result of the dropping out of the potential switch. Also the separation of contacts CXI causes the dropping out of relay DL and switch G0 which reengage contacts DL3 and GC4 to complete the circuit for the coil of gate open switch GO. Switch GO operates to cause the opening of the car gate and the unlocking of the second floor hatchway door. As the gate reaches open position gate open limit switch GOL opens to deenergize switch GO and relay G. Relay G engages contacts G2 to render brush H5 efiective to cause the reset of floor relay 2D. The exciter set is maintained in operated condition,

however, as contacts ICI of floor relay IC re- I main in engagement.

The engagement of contacts G04 as a result of the dropping out of switch GO as the gate reaches open position reestablishes the circuit for the coil of time relay Z. This gives the intending passenger the interval provided by this relay in which to open the hatchway door and enter the car. Should this not occur within this time interval, contacts Z2 reengage to cause the relccking of the load weighing device in load weighing position, reclosure of the car gate and locking of the second floor hatchway door and the restarting of the car in the down direction. Assume, however, that the passenger opens the door and enters the car. As he opens the door relays O and SS are deenergized, relay 0 cancelling the time interval of relay Z. Upon the reclosure of the door relay 0 reengages contacts OI which immediately completes a circuit for the operating coil of call pick up relay S through contacts and. AB3 causing the locking of the load weighing device in load weighing position and reclosure of the car gate and locking of the hatchway door and restarting of the car in the down direction, without waiting for the expiration of the time interval of relay Z. It is to be noted that as there are now two passengers in the car lever 34 is swung further clockwise about its pivot from the position illustrated in Figure 3.

As the car nears the first floor, brush I35 engages contact 13! picking up the call and resetting the call pick up relay. The consequent reengagement of contacts S2 renders the inductor effective for cooperation with the hatchway plate for the first floor. This cooperation takes place at a greater distance from the first floor than was the case with the previously assumed stop at the second floor owing to the fact that there are now two passengers in the car. The separation of inductor switch contacts INDl breaks the circuit for the coils of switches C and B causing the car to be brought to a stop at the first floor. Also the car gate is opened and the first floor hatchway door is unlocked. As the gate reaches open position relay G is deenergized causing the reset of first floor relay i0 and the exciter set is shut down.

It is believed that it will be understood without further description that all push buttons, once pressed, are responded to, inasmuch as they act through floor relays which are latched in operated position and remain so until the car stops at the corresponding floor in response to the push button. The car buttons are responded to during travel of the car in each direction, brush 13'! being effective to pick up car calls during up travel and brush I35 during down car travel. Hall buttons D3 and D2 are responded to during downward travel of the car, brush H5 being effective to pick up these calls under such conditions. During upward travel of the car it may be stopped in response to hall button D3 or hall button D2 provided no call is registered for a floor beyond to maintain relay AU operated. However, the car on its upward trip may be stopped at the second floor in response to hall button 2U even though calls are registered for floors above, brush E21 being effective to pick up this call. Contacts Zl prevent the immediate establishment of a direction circuit by a hall button floor relay upon the last stop of the car in its direction of travel. For example, should the car on its upward trip be stopped at the third floor in response to push button D3 contacts 21 remain separated until the passenger has had time to open the door and, after entering the car and reclosing the door, until the passenger has had time to press the car button for his destination, thereby giving preference to car buttons for establishing direction of car travel under such conditions.

The locking magnet and inductor switch are deenergized each time a stop is made so that the load is reweighed for each stopping operation. The more load that is on the car the more lever 34 is swung clockwise about its pivot, Figure 3. ihus the more load on the car the less the stop initiating distance for stops during up car travel and the greater the stop initiating distance for stops during down car travel. Thus compensation is provided for the load on the car to cause the car to be brought to a stop at the floors.

It is to be understood that various changes may be made in the particular arrangement shown and specifically described. For example, the construction of the locking mechanism may be varied and it may be used with other arrangements of load weighing mechanism. Although the invention has been described as applied to a three phase alternating current installation, it is applicable to installation of other numbers of phases and also to direct current installations. A slow speed installation has been chosen to illustrate the invention and, although the invention is particularly applicable to such installations, it is also applicable to higher speed installations in which the load weighing mechanism may be employed to cause initiation of the slow down operation at various distances from the floor with the stopping operation effected as another step. Also, although a control system has been described in which the car is controlled by push buttons which act to register calls and in which the calls remain registered until responded to, it is to be understood that the invention is applicable to other types of push button systems such as single call push button systems and to systems in which operation of the car is controlled in other ways such as those in which the starting of the car is under the control of an attendant in the car with slow down controlled by passengers and intending passengers themselves or those in which the slow down and starting are under the control of a car attendant, with the slow down initiated automatically after movement of the control switch in the car to a certain position.

Thus it is apparent that many changes could be made in the arrangement and control of the load weighing mechanism and many apparently widely diiferent embodiments of the inventioncould be made without departing from the scope thereof, and it is therefore intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. An elevator installation in which an elevator car serving a plurality of floors is provided with resilient means for supporting the load and in which lever mechanism is provided which is movable in accordance with the deflection of said resilient means to weigh the load in the car and in which means is provided for initiating slow down of the car at a distance from a floor at which a stop is to be made determined by the position of said lever mechanism, characterized in that means is provided which is operable after the load has been weighed but before the car starts to hold said lever mechanism in the position to which it was moved during the load weighing operations.

2. An elevator installation in which an elevator car serving a plurality of floors is provided with resilient means for supporting the load and in which lever mechanism is provided which is movable in accordance with the deflection of said resilient means to weigh the load in the car and in which means is provided for initiating slow down of the car at a distance from a floor at which a stop is to be made determined by the position of the outer end of said lever mechanism, characterized in that electromagnetically operable means is provided for holding said outer end of said lever mechanism in load weighing position, and in that said lever mechanism is yieldable to allow for any deflection of said resilient means while said outer end of the lever is held.

3. An elevator installation in which an elevator car serving a plurality of floors is provided with lever mechanism for amplifying at the outer end thereof the deflection of resilient means interposed in the connection of the hoisting ropes to the car for weighing the load, and in which means is carried by said outer end of said lever mechanism and movable thereby into positions for cooperation with stationary means in the hatchway for said floors to initiate stopping of the car atdistances from the fioors at which' stops are to be made determined by the load in the car, characterized in that'an electromagnetically operated pawl is provided for engaging a rack to lock said outer end of said lever mechanism in load weighing position, and in that said lever mechanism is yieldable to allow for any defiection of said resilient means after said outer end of the lever has been locked.

4. An elevator installation in which an elevator car serving a plurality of floors is provided with lever mechanism for amplifying at the outer end thereof the deflection of resilient means interposed in the connection of the hoisting ropes to the car for weighing the load, and in which means is carried by said outer end of said lever mechanism and movable thereby into positions for cooperation with stationary means in the hatchway for said floors to initiate stopping of the car at distances from the floors at which stops are to be made determined by the load in the car, characterized in that said resilient means comprises rubber arranged between the car frame and the hitch plate for the hoisting ropes and having a plurality of holes to provide a certain ratio of bulge area to eifective supporting area, with said effective supporting area greater than the square of the thickness.

5. An elevator installation in which an elevator car serving a plurality of floors is provided with lever mechanism for amplifying at the outer end thereof the deflection of resilient means interposed in the connection of the hoisting ropes to the car for weighing the load, and in which means is carried by said outer end of said lever mechanism for cooperation with stationary means in the hatchway for said floors to initiate stopping of the car at distances from the floors at which stops are to be made determined by the load in the car, characterized in that said resilient means is a rubber pad, and in that means is provided for holding said lever mechanism in load weighing position.

6. An elevator installation in which an elevator car serving a plurality of floors is provided with lever mechanism for amplifying at the outer end thereof the deflection of resilient means interposed in the connection of the hoisting ropes to the car for weighing the load, and in which means is carried by said outer end of said lever mechanism for cooperation with stationary means in the hatchway for said floors to initiate stopping of the car at distances from the floors at which stops are to be made determined by the load in the car, characterized in that said resilient means is a rubber pad arranged between a hitch plate to which the hoisting ropes are connected and the car framework, in that the cooperating means carried by said lever mechanism comprises an inductor switch, with inductor plates as the stationary means, and in that means is provided for latching said lever mechanism in load weighing position.

'7. An elevator installation in which an elevator car serving a plurality of floors is provided with lever mechanism. for amplifying the deflection of resilient means interposed in the connection of the hoisting ropes to the car for weighing the load. and in which means is movable by said lever mechanism into position for cooperation with stationary means in the hatchway for said floors to initiate stopping of the car at distances from the floors at which stops are to be made dete'- mined by the load in the car, characterized in that said resilient means is a rubber pad arranged between a hitch plate to which the hoisting ropes are connected and the car framework and that said lever mechanism comprises an inner lever and an outer lever both pivotally mounted on said car framework with the inner end of said inner lever provided with means associated with said hitch plate to measure the compression of said pad by the load in the car, in that the cooperating means movable by said lever mechanism comprises an inductor switch carried by the outer end of the outer lever, with inductor plates as the stationary means, and in that means is provided for locking said outer lever in load weighing position.

8. An elevator installation in which an elevator car serving a plurality of floors carries means for cooperating with stationary means in the hatchway for the floors to initiate stopping of the car at said floors, and in which the cooperating means carried by the car is movable by lever mechanism, connected to amplify the deflection of resilient means interposed in the connection of the hoisting ropes to the car for weighing the load, into positions for cooperation with said stationary means at distances from the floors at which stops are to be made determined by the load in the car, characterized in that said resilient means is a rubber pad arranged between a hitch plate to which the hoisting ropes are connected and the car framework and that said lever mechanism comprises an inner lever and an outer lever both pivotally mounted on said car framework with the inner end of said inner lever provided with means associated with said hitch plate to measure the compression of said pad by the load in the car, in that the cooperating means carried by the car comprises an inductor switch carried by the outer end of the outer lever, with inductor plates as the stationary means, in that means is provided for locking said outer lever in load weighing=position, and in that said lever mechanism is yieldable to allow for movement of said rod with respect to said outer lever due to relative movement between said car framework and hitch plate after said outer lever has been locked.

9. An elevator installation in which an elevator car serving a plurality of floors carries means for cooperating with stationary means in the hatchway for the floors to initiate stopping of the car .s

means is a rubber pad arranged between a hitch plate to which the hoisting ropes are connected and the car framework, in that a downwardly extending measuring rod rests on said hitch plate to measure the compression of said pad by the load in the car, said lever mechanism comprising an inner lever and an outer lever both pivotally mounted on said car framework with the inner end of said inner lever connected to said rod. in that the cooperating means carried by the car comprises an inductor switch carried by the outer end of the outer lever, with inductor plates as the stationary means, in that an electromagnetically operated pawl is provided for engaging a rack to lock said outer lever in load weighing position, in that said inner lever has a toggle joi t yieldable to allow for movement of said rod with respect to said outer lever due to relative movement between said car framework and hitch plate after said outer lever has been locked.

it. An elevator installation in which an elevator car serving a plurality of floors carries means for cooperating with stationary means in the hatchway for the floors to initiate stopping of the car at said floors, and in which the cooperating means carried by the car is movable by lever mechanism, connected to amplify the deflection of resilient means interposed in the connection of the hoisting ropes to the car for weighing the load, into positions for cooperation with said stationary means at distances from the floors at which stops are to be made determined by the load in the car, characterized in that said resilient means is a rubber pad arranged between a hitch plate to which the hoisting ropes are connected and an upper plate beneath the upper cross members of the car framework, in that a m asuring rod extends downwardly through aperture provided in said upper plate and pad to rest on said hitch plate to measure the compression of said pad by the load in the car, said lever mechanism being connected to said rod and comprising an inner lever and an outer lever both pivotally mounted on said cross members with the inner end of inner lever connected to said rod, in that a spring acting through the inner lever is provided to bias said measuring rod into engagement with said hitch plate, in that the cooperating means carried by the car comprises an inductor switch carried by the outer end of the outer lever, with inductor plates as the stationary means, in that a rack is mounted on the outer lever adjacent th switch and an electromagneticall operated pawl is mounted on said cross inem. ers for en aging said rack to lock said outer lever in load weighing position before the car is started, and in that said inner ever has a toggle joint yieldab-le to allow for movement of said rod with respect to said outer lever clue to relative movement between said car framework and hitch plate after said outer lever has been locked.

SELDEN BRADLEY SANFORD.