US2669324A - Automatic landing elevator system - Google Patents

Description

Feb. 16, 1954 A. o. LUND 2,669,324

AUTOMATIC LANDING ELEVATOR SYSTEM Filed June 26, 1952 2 Sheets-Sheet l R9 FigJ. Am

i 350 S4l I TI R7 "L6H 17H) T "8 A 5H4! 4E3 INVENTOR M M9 05 EP E2 mo E E A|vinO.Lund.

m? gag 8% R8 ATTORNEY 2 Sheets-Sheet 2 INVENTOR Feb. 16, 1954 A. o. LUND AUTOMATIC LANDING ELEVATOR SYSTEM Filed June 26, 1952 Fig.|A.

Patented Feb. 16, 1954 UNITED STATES PATENT OFFICE 2,669,324 AUTOMATIC LANDING ELEVATOR SYSTEM Alvin '0. Lund, Great Notch, N. J., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application June 26, 1952, Serial No. 295,705 18 Claims. (01. 18729) This invention relates to apparatus for con- Which it is to stop, the adjustment of the braktrol ing the position of a movable body and it ing efforts enables the elevator car to stop achas particular relation to automatic landing curately at the desired point regardless of the elevator systems wherein an elevator car is landed load carried by the car. accurately at a floor regardless of the load car- It is therefore an object of the invention to ried by the elevator car. provide an improved system for controlling the In automatic landing elevator systems it is the position of a movable body.

practice to initiate a. stopping operation of a It is another object of the invention to provide moving body such as an elevator car at a predeimproved load-responsive braking apparatus for termined distance from a point at which the body a moving body.

is to stop. If the load represented by the body It is a further object of the invention to proremains constant, accurate stopping operations vide load-responsive mechanical and electrical may be obtained. However, if the load reprebraking for a movable body.

sented by the body is subject to variation, the It is also an object of the invention to provide body may undershoot or overshoot the point at an elevator system wherein load-responsive which it should stop One solution for trllS promechanical and electucal braking are initiated a blem W111 be found in my copending appl cation, predetermined distance from a point at WhlCn Serial No 206,407 filed January 1'7, 1851 now an elevator car is to stop.

Patent No. 2,641,337. It is an additional object of the invention to Although aspects of the invention are suitable 20 provide a control device for a variable load which for various types of moving bodies, the invention includes a stepping switch responsive to the is particularly suitable for elevator systems and magnitude of the load will be described with reference to a moving body It is a still further object of the invention to in the form of an elevator car. provide an elevator system wherein the brakin In an elevator system both mechanical and of an elevator car is controlled by the position of electrical braking have been employed. The a stepping switch which is responsive to the mechanical brake conventionally is spring-apload carried by the elevator. plied and is released in response to energization Other objects of the invention Will be apparent of an electrical motor which may be in the form from the following description taken in conjuncof a solenoid operating on a magnetic armature. tion with the accompanying drawings in which: Dynamic braking is well understood in the art, Figure 1 is a schematic view with circuits shown and may be employed not only for direct-current in straight line form of an elevator system emmotors but for alternating-current motors such bodying the invention. as induction motors to which direct current, for Fig. 1A is a key representation of electroexample, may be supplied for braking purposes. magnetic switches and relays employed in the In accordance with the invention, the braking system of Fig. 1. If Figs. 1 and 1A are placed in of an elevator car is varied in accordance with horizontal alignment it will be found that corthe loading of the car. Such variation may be responding coils and contacts of the switches introduced in the mechanical braking or in the and relays are substantially in horizontal alignelectrical braking, but in a preferred embodiment ment.

of the invention, the variation is introduced in Fig. 1B is a schematic view of a stepping switch both mechanical and electrical braking efforts. employed in the system of Fig. 1.

In a preferred embodiment of the invention, a Fig 1C is a vector diagram illustrating certain load-responsive device measures the load carried voltage relationships in the system of Fig. l, and by an elevator. In addition, a source of energy 5 Fig. 2 is a view in elevation with parts scheis scanned to provide a variable output. The matically shown of an inductor relay employed scanning of the source may be effected by a stepin the system of Fig. 1. ping switch which is responsive to the difference The relays and switches employed in the elevabetween the quantity measured by the load-retor system of Fig. 1 may have break or back consponsive device and the output obtained from the tacts which are closed when the relay or switch source of energy. Adjusting devices are then is deenergized and dropped out. Each of the recontrolled by the stepping switch for the purpose lays and switches employed in the system of Fig. of adjusting braking efforts of mechanical and 1 may have front or make contacts which are electrical braking apparatus. If a stopping operclosed when the relay or switch is energized and ation of the elevator car is initiated at a predepicked up.

termined distance from, a point or floor from Each set of contacts of a relay or switch is make contacts M6 of justed in accordance with a function of the loading of the motor I! for the the braking eifort as a function of such loadings.

The car switch CS is shown vator car Ill, but in association with circuits which are controlled by the car switch. It will be noted that the car switch normally occupies a stopping position wherein it connects a contact CS2 to the bus L4. Such connection controls in part the energization of a stop control relay S. The

through either make contacts M4 of the running relay or make contacts 'IOTI of a first timing relay.

The car switch CS may be moved by the car attendant to an up position wherein it connects a contact CS3 to the bus L4. In this position, the car switch completes the following circuit: L4, CS, CS3, U, LUI, 22, M, L5. This circuit includes a limiting switch 22 which is normally closed, but which is cam operated to open as the car switch.

The car attendant also may operate the car switch to a down position wherein the car switch connects a contact CSl to the bus L4. In this position the following circuit is completed: L4, CS, CSI, D, LDl, 23, M, L5. This circuit includes a limit switch 23 which is normally closed buses L4 and L5 in series with the make contacts M5 of the running relay and the break contacts F3 and F4 of the inductor relay. Under certain conditions, the break contacts F3 and F5 are bypassed through break contacts S4 of the stop control relay.

When the elevator car is conditioned to run, the first timing relay 1BT is energized through the running relay. The relay 'lilT has a time delay in drop out which is provided in any suitable manner. For example, in Fig. 1 a resistor R6 is connected across the coil of the relay for the purpose of delaying drop out thereof.

Break contacts M1 of the running relay control the energization of a second timing relay T. This relay also has a time delay in drop out which is provided in any suitable manner as by connection of a resistor R7 across the coil of the relay.

The auxiliary relay A may be energized from the buses L4 and L5 through break contacts I IT! The third timing relay T is energized from the buses L4 and L5 through the make contacts A4 6 of the auxiliaryirelay and the make contacts MlO of the running relay. The third timing relay has a time delay in drop out which is provided in any suitable manner as by connection of a resistor R8 across the coil of the relay.

It will be recalled that the adjustable resistors RI and R4 are adjusted in accordance with a function of the loading of the motor IT. This function is determined by apparatus which includes three transformers 25, 26 and 21. The transformer 25 has a primary winding connected across a resistor R! which is inserted in the bus LA. Consequently, the secondary winding of the transformer has an output voltage El which represents the current supplied to the phase winding IlA from the bus LA.

The transformer 26 has a primary winding connected for energization by the phase voltage E which is applied to the phase winding l'lA of the motor. (Conveniently, the voltage E may be applied to the phase winding HA and one or more of the resistors RA, RB or RC as shown). The secondary winding of the transformer 26 has a resistor RIB connected thereacross.

across a resistor RI adjustable tap 29 associated therewith to provide an adjustable voltage E3 which is dependent on the phase voltage appearing across the buses LB and LC.

By inspection of Fig. 1, it will be observed that the three voltages El, E2 and E3 are combined vectorially in series. The resultant is applied through a rectifier 30 across an output resistor RIZ. A capacitor 3i is connected across the output resistor R12 for the purpose of bypassing any alternating component of the energization of the resistor.

The nature of the output appearing across the resistor RI 2 may be understood from a considera tion of the vector diagram illustrated in Fig. 1C. The phase voltage appearing across the phase winding l'lA of the motor I1 is represented in Fig. 1C by a vector E which is substantially constant in magnitude. The output voltage El of the transformer-25 is represented in Fig. 10 by a vector El which lags the reference voltage -E. It will be recalled that the voltage E l varies in accordance with the phase current supplied to the phase winding HA of the motor.

The voltage El may be divided into two vector ponent EQ. Consequently, the resultant of the outputs of the transformers 25 and 2'! is represented by the vector component EP and this component represents the rea1 power supplied to the motor.

The voltage E2. isderived from the transformer 7 26. The voltagetEZ hasa. phas nelativev to. the vector 'EP and :a -magnitudennihich1maywbe zadjusted to control the magnitude of theresultant output.

It is conventionalpractice in the elevator field to provide a counterweight 'l twhichbalances. the weight of the elevatorrcar 110 plus 40% 9f the rated load capacity of athegelevator car. .For this reason, the elevator motor 11 :1 requires maximum power when carrying aiull load in the up direc- .tion. For an overhaulingload, the motor l1 .gencrates power and the voltage E consequently swings substantially 180 in phase relat'meto the voltage E2.

In the preferred embodiment of. the invention 1 the voltage E2 compensates ;for :ahreeenerative value of the voltage vEP. the phase and magnitude of the voltage EZaresoadjustedthat if the elevator car is moving .down with a full load (i. e. an overhauling load) the resultant voltage appearing across theresistor R12 is substantially zero. With this adjustment, if, the elevator car is moving .up with ;a full load-the voltages E2 and EP are fin phase and .aJna-Ximum voltage appears across the ;;resistor Hit.

The output appearing across the 'resistor R12 is employed for .controllingthe adjustment of the resistors RI and B4. In a preierred embodiment of the invention, the output appearing across the resistor R|2 controls the position of a stepping switch which in turn controls the adjustment of the resistors fRl and as.

The stepping switch STP is of conventional .construction and may 'be .underetoodyirom. a consideration of Fig. 1B. The stepping switch includes a shaft 35 having four double-ended wipers or contact arms 35A, 35B, 35C and 35D secured thereto. The wiper 35A is employed for adjusting the efiective resistance value of the resistor RI. The wiper 35B is employed for adjusting the effective resistance value of the resistor R4. The wiper 35C duringsuccessivestepping thereof successively engages contacts arranged in a semicircular bank. Onlyoneofthese contacts 35E actually is employed for resetting purposes. The wiper .35D is employed .for .controlling the effective resistance value of a resistor RM.

The shaft 35 also has secured thereto aratchet wheel 3515. This ratchet wheel is successively stepped in the direction of the arrow by-reciprocation-of a pawl 35G. When the coil'of thestepping switch STP is energized, an armature associated therewith lifts the pawl 35(3- and simultaneously opens the break contactsSTPl. Opening of thecontacts STPI is employed .for deenergizing the coil of thestepping switch and :the pawl thereafter drops under the influence of gravity or preferably a spring (not shown) to advance the ratchet wheel .for an :angular distance equivalent to one step. Such operation of a stepping switch is well known in theart. The number of steps required to rotate :oneuo'f the wiper ends across its associated resistor maybo the specific application. As an selected to suit example, twenty steps have been found adequate for someelevator applications of thetype herein discussed.

As shown 'in Fig. 1-, the coil of the stepping switch STP-is energized from a secondary winding of a transformer thunder the control of an electrical discharge device lii, the break contacts STPI and the makecontacts LUZ and 112132 The electrical discharge device 3'7 may be of any suit- .able type wherein the :output current thereof may be controlled in in conductive condition,

from one terminal the transformer 36 a suitable manner. Iii-the specific embodiment of Fig. the -.electrical dis.- charge device takes the form of an electronic tube having a cathode 31A, a first grid or'con- .trol electrode 313, a second grid or control electrode 31C and an anode 319. When the tube an energizing circuit for the coil of the stepping s tch may be traced of the secondary winding .of through the contacts LD2, LUZ, STPI, the coil of the stepping switchSTP, the anode 31D, the cathode -3iA to the remaining terminal of the secondary'winding. The primary winding of the transformer 36 is energized from, a suitable source of alternating current which may, for example, operate at the conventional power frequency of 60 cyclesper second.

the type designation Although the tube may be of the high vacuum type, a. thyratron tube such .as one sold under 2050 is considered to be very satisfactory.

In-order to improve the operation of the stepping switch a rectifier 33 may be connectedacross the coil, of the switch or preferably across the coil and the contacts STPi as shown. This rec- "tifierpermits current to flow therethroughin the direction of the arrow. 'Iildesired a capacitor Cl and aresistor are may be connected across the contacts STE to decrease arcing thereon The rectifiers employed in Fig. .1 may be oiany suitable type, but preferably are ofthedry-type such as those known as copper oxide or selenium rectifiers.

13:18 is connected to resistor R15 and the .cated between the two By inspection of Fig. 1 it will be observed that the resistors El i and Ri'i are connected in series across a source of direct current represented by a positive bus Li and a negative bus L6. The positive bus also is connected to the cathode 31A of the discharge device. Consequently, when the stepping switch is in reset condition, the second :grid 33.0 is maintained negative relative to the cathode 33A to prevent occurrence of a discharge .be'tween thecathode and anode of the discharge device. A filter capacitor is connected between the first grid 37B and the cathode, anda filter capacitor 11,

"3113 and th cathode a resistor R20, the the-resistor RI 4,-andtheresistor R I] to metathis connected between the wiper 35D andthe positive bus Ll.

. When thestepping switch is to step to a position corresponding to the loading of the motor 1], the 'break contacts SI and S3 open. Opening of the contacts S3 removes the negative bias applied to the second grid t'iC. The ,secondgrid 310 now is connected to the cathode only through aresistor R l 8.

The voltage appearing between the first grid 3M. now depends on the difference between the voltage derived from the voltage divider represented by the resistors RM and RH, and the voltage derived from the resistor R12. The biasing circuit may be traced from the first grid 3'iB through the resistor Hi6, resistor R1 2, the wiper 35D,

stepping switch S'I'P.

As the stepping switch operates, the wiper 35D moves in a clockwise direction as viewed in Fig. l to increase the grid voltage derived from the voltage divider represented by the resistors RM and tinues until the grid voltage derived from the voltage divider substantially balances the voltage appearing across the resistor RI2. The position of the stepping switch then corresponds to switch is to be reset, the break contacts SI and S3 of the stop control rethe contacts SI connects contact 35E.

Because of the connection of the first grid 3713 to the cathode, the discharge device 31 again A complete operation of the elevator system now will be set forth.

Initially, it will be assumed that the elevator car ID is located at the lower terminal floor and that the stepping switch is in its reset condition represented by the dotted line positions of the wiper arms in Fig. 1. Under the assumed condi tions, break contacts Fl and F2 of the inductor relay are closed and the up stopping relay LU and the down stopping relay LD are energized and, picked up.

The car attendant now operates his car switch CS to engage the contact CS3 and complete the following circuit: L4, CS, CS3, U, LUI, 22, M, L5. As a result of its energization, closes its make contacts car switch CS.

At the same time energization of the running relay M re ults in closure of the make contacts MI and M2 to'energize the motor Closure of make contacts M4 has no immediate effect on the operation of the system, Closure of make in the energizing circuit for the brake coil. This reduces the current flowing through the brake coil to a value merely suflicient to maintain the brake in released condition.

Returning to the cheat of the energization and pick up of the running relay, it should be noted timing relay HIT. This relay closes its make contacts 'IOTI without immediately affecting the operation of the system.

Opening of the break contacts M! deenergizes the second timing relay HT and this relay now starts to time out. Contacts M8 and M 10 close and break contacts M9 open without immediately affecting the operation of the system.

Upon expiration of the time required for the relay II T to drop out, this relay closes its break contacts H T l to complete through the closed contact M8 an energizing circuit for the auxiliary relay A.

As a result of its energization, the auxiliary relay A closes its make contacts Al and A2 to shunt the resistors RA, RB and RC. Such shunting applies full energization to the motor I! and conditions the motor for full speed operation of the elevator car in the up direction. The auxiliary relay also closes its make contacts A3 to energize the primary winding of the transformer 21. A Voltage now appears across the resistors RIZ which depends on the loading of the motor l1.

Closure of the make contacts A4 completes through the closed make contacts M H) an energizing circuit for the third timing relay T. The relay T thereupon closes its make contacts TI to establish a holding circuit for the auxiliary relay A.

Let it be assumed tendant desires to st A suitable distance that the elevator car atp the car at the third floor.

tacts CS2. are closed, the stop control relay S is energized as a result of such centering of the car switch.

The stop control relay opens its break contacts S to apply between the first grid 37B and the cathode 37A of the discharge device a voltage dependent on the diiference between that apby the resistors RI 4 and RH. break contacts bias from the second grid 31C.

The parameters of the system are assumed to be the up direction an overhauling load having a smaller magnitude is applied to the elevator motor and voltage appears across the resistor RIZ. For increases in the load carried by the apogee;

1'1 up-traveling elevator car the voltage across the resistor R12 also increases.

It will be assumed that the rip-traveling elevator car IE3 is so loaded that a voltage appears across the resistor R52 requiring stepping cf the stepping switch from the zero position represented by the dotted line positions of the wipers to the position represented by the fullline positions of the wipers in Fig. 1. Under these conditions, a positive bias is applied to the first grid 31B and the discharge device 31 conducts to energize the coil of the stepping switch. The stepping switch now steps until the wiper 35D collects a sufhcient voltage from the associated voltage divider to balance substantially the voltage appearing across the resistor R12. The'stepping switch then'remains in the position which is determined by the loading of the motor H.

The pick up of thestop control relay is also accompanied by closure of the make contacts S2 to energize the inductor relay F. However, such energization alone is insufiicient to pickup any or" the contacts of theinductor relay. It will be recalled that in addition to'energization of the coil of the inductor relay, .each of the inductor relay contacts must be adjacent one or its associated inductor platesbefore such contacts can open. Opening of the break contacts S hasno immediate effect onthe system operation.

When the elevator oar reaches apredetermined distance in advance of the third floor-which may be of the order of 15 inches, the contacts F3 oi the inductor .relay reachthe up inductor plate for the third floor and 'these'contacts thereupon open to deenergize the brake relay BR.

Deenergization of the .brakerelay results in openingof themake contacts BR! tointroduce the resistor R3 n the energizing circuit for the brake coil .13. The resulting decrease'in energization of .the brake ooil'B initiatesa decay in the magnetic flux of'the "brakecoil. .It will be assumed that 'such'decay'does not result in application of thebrake shoe 2| to the drum 2%.

During continued motion 'of the elevator car, the contacts F! of the inductor relay plate reach the inductor plate for the third floor and open to deenergize the up stopping relay LU. This may occur at a suitable distance from the third floor which may for example be of the order of 9 inches for a slow speedelevatorcar.

The'up stopping relay LU .opensLthe-make contacts LUZ to prevent movement of the stepping switch during the stopping .operation. In addition, contacts LU! open to deenergize the up switch U and the running. relay M. The running relay M opens its make contacts MI and M2 to deenergize the elevator motor I]. In addition, the make contacts M3 open to deenergize the brake coil B.

The energy stored in thebrake coil B'now'discharges through'the resistor'R i and the "rectifier R5. The resistor Rd has aresistance'value as'determined by-the position of the wiper 3513 which is properly coordinated for the purpose of stopping the elevator'car l8 accurately at the third floor regardless of the magnitude of the load carried thereby. 'In the reset position of the wiper 3513 the resistor Rd has a maximum efiective value. stepping switch which followed the pick up of the stop control relay S-decreased the effective resistance to a value determined by the car loading. Opening oi1the make contacts Mdand M5 has no immediate effect on the operation of the system.

However, the stepping of the F The running relay also opens its make contacts M6 to deenergize the first timing relay 'iilTand this relay now starts to time out. Closure of break contacts Ml energizes the second timing relay liT-and the relay opens its break contacts HT! without immediately afiecting the operation of the system. Opening of make contacts M8 also has no immediate efiect on the operation of the system.

' The closure of the break contacts M9 of the running relay energizes the dynamic braking relay DB through the closed contacts A4. The dynamic braking relaycloses its make contacts DB1, DB2 and DB3 for the purpose of applying direct current to the phase winding 11C of the motor ll. The magnitude of the resultant dynamic'braking is dependent on the position of the wiper 35A and thisposition is coordinated with-the remainder of'the system to stop the elevator car accurately at the third floor .regardless of the loading thereof. In the reset position of the wiper 35A the resistor BI is inefiective for limiting the energization of the primary winding of the transformer Hi. However, the stepping of1the stepping switch'iollcwing-the pickup of the stop control relay S progressivelyincreasesthe efiectiveresistance of the resistor'Rl until'it reaches a value representative of the car loading.

Returning to the running relay, this relay also opens its make contacts MID to .deenergize the third timing relay T and this relay now starts to timeout.

At the expiration of its time delay, the third timing relay T drops out to open its makecontacts Tl. This results in deenergization and drop out or" the auxiliary relay A. The relay .A opens its make contacts Al, A2 and A3, but such opening does not immediately affect the operationo'f'the system. Make contactsAd open to deenergize the dynamic braking relay DB. This relay opensitsmake.contactsDBl, DB2 and-DB3 to terminate the supply-ofdirect current to .the motor I1.

Upon expiration of its time delay the relay 'ifii'I drops out .to open its contacts 'ESTJ. This results in deenergizationof the stop control relay S. The control relay closes its break contacts S! to connect the first grid 3130f thedischarge device to the cathode through the resistor RIG. Contacts S3 close, but have no immediate effect on the cperationof the system. Closure of contacts .St has T-IlO immediate effect on the operation of the system.

Dropout of the stop control relay also I results in opening ofthemake contacts S2 to deenergize the inductorrelay F. This relay thereupon recloses itsbreak-contacts El and F3. Closure of the contacts F3 has no immediate eiiect on the operation of the system. Closure of the-contactsFl results in-energization of the up-stopping relayLU.

The up stopping 'relay'closes its make contacts LU; without immediately affecting the operation of the system. "However closureoimake contacts LUZ completes an'energizing circuit for the stepping relay. lt'willbe recalledthat at the time of such closure thefirst grid tlBis'connected to the cathode through the-resistor EH6 and the contacts SI. At the same time, the secon'd'grid BECis connectedto the cathode through the yresistorRlt. .Under these conditions, "the discharge device 331 conducts and "the stepping .switch stepsruntil'rthe wiper .3 ECsengageszthecontact 35E, :iSuch engagement'places arnegative tacts CS1 and complete the following circuit: [4, CS, CSI, D, LDI, 23, M, L5. The down switch D closes its make contacts Di and D2 to pretacts D3 close to prepare the brake B for ener- Make contacts D4 close to establish a bypass around the car switch.

The running relay M operates in the manner previously described for up travel of the elevator car. However, since the closure of contacts DI and D2 conditions the system for down travel, it follows that the elevator car now moves away from the third iloor in the down direction.

As the elevator car nears the second floor, the elevator car attendant centers his car switch CS to complete an energizing circuit for the stop control relay S. This relay operates in the manner previously discussed to energize the inductor relay and to initiate a stepping operation of the stepping switch for the purpose of adjusting the stepping switch in accordance with the loading of the elevator motor.

When the elevator car reaches a distance such as 15 inches in advance of the third floor, the break contacts F4 of the inductor relay reach the down inductor plate for the second floor and open to deenergize the brake relay BR. Upon deenergization, the brake relay operates in the "manner previously described to decrease the energization of the brake coil.

When the elevator car reaches a predetermined distance such as 9 inches in advance of the second. floor, the contacts F2 of the inductor relay reach the down inductor plate for the second floor and open to deenergize the down stopping relay LD. The down stopping relay ID opens its make contacts LDI to deenergize the down switch D and the running relay M. In addition, the make contacts LDZ open to prevent operation of the stepping switch during the stopping operation.

The running relay M upon deenergization operates in the same manner discussed for the stopping of the elevator car during up travel in order to stop the elevator car accurately at the second floor. Upon the deenergization the down switch D returns its contacts to the conditions illustrated in Fig. 1.

With the assumed parameters it will be noted that when the elevator car travels down with a full load the stepping switch is positioned at the beginning of a stopping operation to apply maximum direct current to the motor, and to introduce the maximum efiective value of the resistor R4 across the brake coil. Consequently, a substantial dynamic braking is available and the brake is rapidly applied. When the elevator car travels up with a full load the stepping switch is positioned at the beginning of a stepping operation to apply minimum direct current to the motor and to introduce a minimum effective value of the resistor R4 across the brake coil. The variations in direct current or dynamic braking and in the rate of application of the mechanical brake is proportioned to assure accurate landing of the elevator car at a floor regardless of the amount of load carried thereby.

Either the adjustment of the resistor R4 or the I predetermined point dynamic braking may be omitted for some application for which a single adjustment suffices. The dynamic braking is particularly desirable,

Although th invention has been described with reference to certain specific embodiments thereof, numerous modifications falling within the spirit and scope of the invention are possible.

I claim as my invention:

1. In a system for controlling a movable body, a structure, a body movable relative to said structure, motive means for moving the body relative comprising first stopping chanically braking said body for adjusting the each of said stopping means in accordance with the energy to be absorbed during a stopping operation of the body.

2. A system as claimed in claim 1 wherein the electric motor is an induction motor, and the second stopping means is effectiv for applying to the induction motor windings direct current having a magnitude which Varies as a function of the energy to be absorbed during a stopping operation of the body.

3. In a system for controlling a movable body, a structure, a body movable relative to ture, means for moving the body relative to the structure, and. control means for controlling movement of the body, said control means comprising first stopping means operable for mechanically braking said body as it approaches a at which it is to stop, second stopping means operable for electrically braking said body as it approaches the predetermined point, means for partially operating said first stopping means as it approaches the point, and means responsive to energy to be absorbed during a stopping operation of the body for operating each of the stopping means to adjust the braking effort exerted by each of the stopping means in accordance with the energy to be absorbed.

4. In a system for controlling a movable body, a structure, a body movable relative to the structure, motive means for moving the body relative to the structure, and control means for controlling movement of the body, said control means comprising first stopping means operable for mechanically braking said body as it approaches a predetermined point at which it is to stop, second stopping means, operable for electrically braking said body as it approaches said predetermined point, means responsive to arrival of said body at a predetermined position in advance of said predetermined point for initiating operations of the first and second means, and means responsive to energy to be absorbed during a stopping operation of the body for adjusting the braking effort exerted by each of th stopping means in accordance with said energy to stop the body accurate- 13 at said predetermined point.

5. In a system for controlling a movable body,

a structure, a body :reprcsenting "-a variableload movable relative 1 to the structure, 'electromotive rneans ior moving the body 'relativeto thestructure, andcontrol means for controlling. movement of th body, said control: means comprising first stopping means operableiior mechanically brak ing saidbody as it approaches apredetermined point ;at which it is torstop, second stopping means operable for supplying direct current .to saidbodyas it approaches saidpredetermined point, means responsiveto arrival of said body at apredetermined position in advance of said predetermined; point iorinitiatingoperations of the first and second means, andmeans'responsive to th magnitude of said load. for adjusting the braking effortexerted'by'the first-stopping means and-for varyingithemagmtude orthe direct current to stop thcabodyaccurately at said predetermined point.

6. In an elevator system,aistructure having a plurality of floors, an :elevator :car movable-with respect to the structureto serve the floors, means including an electricinotor for moving the elevator-car relative to the iioors,'-amechanical brake operable for stopping the elevator carat any of saidfloors, auxiliary braking operable for conditioning theelectric motor to act as a dynamio brake,initiating means operable a predetermined distance :fromeachof the floors for initiating a stopping operation oftheelevator car :as'it approachesa floor at which itis to stop, and adjusting vmeans responsive to the load on said elevator *oarior adjustingithebralrin'g effort exerted'by the mechanical-brake and for adjusting thgbraking-"efiort exerted by thedynarnic brake to stop theelevator caraccurately at any of the floors for which a stopping operation is initiated.

"Z. An elevator system as claimed in claim 5 wherein the adjusting .meansis responsive to the power supplied tosaid motor for moving the elevator car.

8. An -elev-ator systemas claimed in claim 6 "wherein the motor 'isan induction motor, and wherein auxiliary meanscomprises a source of direct current and connections for energizing the induction motor from said source to produce dynamic braking of theelevator car, said adjusting meansbeing effective'for adjusting the magnitude-oi the direct current supplied to said induction motor.

9. An elevator system as claimed in claim '6 wherein the adjusting means comprises a stepping'switch, means for'stepping' the switch to a positioncorresponding to the elevator car load, and means responsive stepping switch for adjusting said braking efforts.

10. In an elevator-system, a structure having 'a plurality of'floors, an'elevator car movable with respect to'the structure to serve the floors, means including an electric motor'for moving the elevator car relative to the floors, a mechanical brake operable for stopping the elevator carat .aany of said floors, auxiliary braking means operable for-conditioning the electric motor to act as .a dynamic brake, initiatingrneans operable when in efiective condition a predetermined distance from each of the floors for initiating a stopping operationof the elevator car as it approaches afioor at'which it is to stop, and addusting means responsive when in efiective condi- --tionto the loadon saidelevator car for adjust- "ing the brakingseffort exertediby. the mechanical brake and for adjusting stheibraking eilortexierted :byrthe dynamic brakeito stopthe elevator to the position of the F6 :car accurately at :any or the 'IfiOOlS :for which a stepping operation is initiated, and effcctuating means operable while the elevator car is in moition'for'placing saidinitiating means and theadjustingmeans in effective condition.

11. Ina system for controlling a movable body, a structura'abody representing a variable load movablerelative to the structure, means includinganelectric motor for moving the body relative to the structure, and control means for controlling movement :of the body, said control means comprisingrmeans connectingthe electric motor'to provide dynamic braking for the body, adjusting means for adjusting the magnitude of the dynamic'braking'efiort produced by the electricimoton'an'd means responsive to the load represented by saidbodyior operating the adjusting means to vary the dynamic braking effort in accordance with a predetermined pattern.

'12. In a system'for controlling ainiovable body, a structure, 'a body'representing a variable load movable relative .to the structure, means'including an electric motor for moving the'body relative to the structure, and control means for controlling movement of the body, said control means :tcomprising braking means for braking said body, adjusting means for adjusting the braking effort of the braking means, a stepping svvitchhaving amovable operating member connected to operate saidadjusting means and'having stepping means operable when in effective condition for successively stepping the operating member to spaced positions, and means for energizing the stepping switch in accordance with the difference between a quantity representing Jsaid load and a 'quantity representing the displacement ofxthe operating member from a predetermined position, whereby the stepping-switch operates the adjusting means to produce a braking erIort having a magnitude dependent on said load.

'13. In a systemfor controlling a movable body, a structure, a body representing a variable load movable relative to the structure, means including aelectric motor for moving the body relative to the structure, and control means for controlling movement of the body, said control means comprising braking means for braking said body, adjusting means for adjusting the braking eilort of the braking means, a stepping switch having a movable operating member connected to operate said adjusting means and having stepping means operable when in effective condition for successively stepping the operating member to spaced positions, and means for energizing the stepping switch in accordance with the difference between a quantity representing said load and a quantity representing the displacement oithe operating member from a predetermined position, whereby the stepping switch operates'the adjusting means to produce a braking effort having a magnitude dependent on said load, operating means operable for placing said stepping means in efiective conditionand initiating means responsive to operation of the operating means forinitiating a braking operation of the braking means upon arrival of the body at a predetermined distance from a point at which the body is to be stopped, said adjusting means controlling the braking effort in accord- ;ance with said variable load to stop said body substantiallyat said point.

1.1.4..In :a load-responsive ldevice, translating meansifor actuating a variableiload, ansoperat- :member, :stepping means operable when in effective condition operating member to spaced positions, translata position dependent on said load.

15. In a load-responsive means for actuating a variable load, an operating a predetermined point at which it is to stop, means responsive on said motive means.

18. In a system for controlling a movable body, a structure,

gardless of the load represented by the body. ALVIN O. LUND.

References Cited in the file of this patent UNITED STATES PATENTS Name Erbe Number Date 2,427,771

Sept. 23, 1947

Images