US1728760A - Control system - Google Patents

Description

R. P. HIGBEE 1,728,760

CONTROL SYSTEM sept. 17, 19,29.

Filed Feb. 17, 1928 INVENTOR @y ed,

TTOR'NEY Patented Sept. 17, 1929 UNITED STATES PATENT OFFICE.

RAY P. HIGBEE, 0F PHILADELPHIA, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA CONTROL SYSTEM Application filed February 17, 1928. Serial N'o. 254,969.

l This invention relates generally to motor control systems and more particularly to control systems for. motors which may be utilized for operating elevators, hoists and similar machinery.

The object of the invention, generally stated, is to provide a control system for elevators which shall be simple and eiiicient in operation and readily and economically manufactured and installed.

A more specific object of the invention is to provide for automatically stopping an elevator accurately at the desired floor level by opening the hatchway door while the slowing-down operation is in progress.

A further object of the invention is to provide for automatically leveling an elevator at the desired floor level, either by unlatching or opening a hatchway door.

Another object of the invention is to provide for automatically maintaining an elevator level with the floor'landing regardless of the variation ot' weight on the elevator during loading and unloading.

Other objects of the invention will be evident from the following description, taken in conjunction with the accompanying drawing, in which,

Figure 1 is a' diagrammatic view ot an elevator-control system embodying the present invention, and

Fig. 2 is a perspective view of an elevator' showing a particular embodiment of the invention.

Referring to Fig. 1 of the drawing, the system shown comprises an elevator car C suspended by a cable Ca which passes over a hoist-ing drum- D to a suitable counterweight Cu, in the customary manner. The hoisting drum D is directly coupled to an elevator motor EM which is illustrated as of the shunt wound type having an armature EM and a separately excited icld Winding EMF.

rPhe control for the elevator motor EM is of the variable-voltage or Ward Leonard type, wherein a driving motor M ofthe shunt-- wound type, comprising an armature M and shunt Atield winding MF, has its armature M directly coupled to the armature G ot a generator G. The generator G is at. the variablevoltage compound-wound type, comprising an armature G', a series field winding GSF, a shunt field winding GF and a demagnetizing field winding GAF. As shown, the armature G of the generator G is connected in loop circuit with the armature EM of the elevator motor EM. The shunt field winding EMF of the elevator motor EM may be excited from any suitable source of direct-current power and is shown as being connected directly across a power supply comprising the line conductors L, and L2. The generator driving motor M is also connected across the same power source, however, control apparatus for the motor MF is omitted for the sake ot obtaining greater simplicity in the drawing.

The elevator motor EM is controlled, in the usual manner, through the agency of a car switch CS on the car C, the usual up7 and down direction switches, designated as 1 and 2, respectively, and a demagnetizing field-control switch 3 the operation ot which Will be described in detail hereinafter.

Referring to Fig. 2 of the drawing, the structure shown comprises an elevator car C carried by the usual type of car sling comprising the cross members ,or channel bars 4, and side. members 5. .Guide shoes 'i' engaging guide rails G which are provided within the hatchway, as shown, for guiding the car C as it is hoisted or lowered by the cables Ca which pass over a drum D, asl illustrated in Fig. 1. The opening in the hatchway at the tloor level is provided with a sliding door 8 which is carried by a track 9`and rollers 11, in the usual manner.

In order to provide for stopping the elevator car C level with the desired floor landing, a levelling device 12, comprising switch members 13 and 14 and an actuating cam 15, is utilized. It will be observed that the switches 13 and 14 are secured to the elevator car C and therewith move within a predetermined perpendicular path in the elevator hatchway.

The switches 13 and 14 are provided with outwardly extending actuating arms 16 and 17, respectively, which are provided with rollers 18 and 19. T he switches are normally biased to the open-circuit position by the tension springs 20 and 21, as shown* `The levelling device 12 may be operated in any suitable manner, when the elevator car C reaches a l)redetern'iined position adjacent to the desired floor landing. As illustrated in this particular embodiment of the invention, a series of cani meinbers 15, one corresponding to each floor level, are supported in the hatchway in the path of travel of the levelling switch arms 16 and 17 by gate devices 23. As shown, the gate device 23 is disposed to swing in a horizontal path within the hatehway, thereby positioning the cani member 15 to engage or disengage the switch arms 16 and 17. 1,., It will be observed that the gate device 23 is normally biased toward theA elevator car C by means of a coil spring 24 which is ot' sufficient strength to actuate either of theV switches 13 and 14 to the closed position against the force of springs or 21 when en- 'l'gaging eithervof these switches.

In order to prevent the cam members 15 yfromengaging the switch arms 16 and 17 When it is desired to pass the floor without stopping, the gate device 23 is provided with an actuating lever 25 which is disposed to engage a projection 26 on the hatchway door 8. It will be readily understood that, when the door 8 is open, the force of the spring 24 holds the cam member 15 -in operative position and, when the door is closed, the cam 15 is removed from the path of the switch arms 16 and 17 by movement of the gate device 23.

In order that a more comprehensive understanding of the invention may be obtained, a detailed description of the operation of the system will be given.

Assuming the elevator car C to be standing at a ,fioor level, the attendant on the car may start the car upwardly by movement of the handle -28 of the car switch CS to the left,

thereby completing a circuit for the up-direction switch 1, which extends from the line conductor L1, through conductor 29, fixed contact fingers 31 and 32 bridged by the movable segment 33 of the car switch CS, conductors 34 and 35, up limit switch 36, conductor 37, operating coil of the 11p-direction switch 1 and conductors 38 and 39, to the line conductor L2.

The 11p-direction switch 1 closes its contact members a and Z), thus supplying the generator shunt field winding GF with exciting current in one direction through a circuit which extends from the line conductor L1, through conductors 41 and 42, contact member of updirect-ion switch 1, conductor 43, generator shunt field GF, conductor 44, contact member a of up-direction switch 1 and conductors 38 and 39, to the line conductor L2. The generator G therefore, supplies voltage in one direction to the elevatormotor armature EM, causing the elevator motor EM to move the car upwardly. ,i v

Assuming that the elevator car C is to be stopped at any desired floor level, the stopping operation may be performed by moving the car switch CS to its original or off position, as shown in the drawing, thereby deenergizing the lip-direction switch 1 which de-energizes the generator shunt field winding GF.

Since it is desirable to dcmagnetize the generator field as quickly as possible, in order to facilitate the stopping of the elevator motor EM, the de-magnetizing field winding GAF, is disposed to be energized upon the opening of the 11p-direction switch 1. However, if the demagnetizing field winding is rendered effect-ive when the speed of the elevator is great the elevator will be decelerated so quickly that smooth deceleration will not be obtained, and, therefore. the action of the de-niagnetizing field GAF is made subject to control of a switch 3. As will be observed, the operating coil of the switch 3 is connected directly across the armature EM of the motor EM and becomes energized when the counter-electrometive force of the motor EM reaches a certain predetermined value, whereupon the switch 3 is actuated to its open position.

It will be readily understood that, when the Lip-direction switch l closes its contact members c, the elevator motor EM is still developing sufficient counter-electromotive force to maintain the switch 3 in the open position and, consequently, to prevent the instant functioning of the demagnetizing field winding GAF. Vhen the speed of the elevator motor drops to a predetermined value, the switch 3 closes its contact members to establish an energizing circuit for the demagnetizing field winding GAF, which extends from one terminal of the motor armature, EM', through conductors 45 and 46, Contact members of the switch 3, contact members o of up-direction switch 1 and contact members c of down-direction switch 2, conductor 47, field winding GAF and conductor 48, to the other terminal of the armature EM.

lFurther control of the elevator car C to automatically stop it level with the desired fioor landing is obtained by opening the hatchway doei' 8 while the car is slowing down for a complete stop. As hereinbefore described, the opening of the hatchway door 8 permits the gate device 23 to swing inwardly and carry the cam member 15 into a position of possible engagement with either of the actuating arms 16 and 17.

Assuming that the car C is within the levelling zone, as defined by the cam member 15, when the hatchway doei' 8 is opened, the roller 18 will engage the lower end of the camv member 15 and thus the switch 13 will be actuated to its closed position. It will be 0bserved that the switch 13 bridges the contact fingers 31 and 32 of the car switch CS by way of a circuit extending from the contact mem ber 31, through conductors 29, 51 and 52,

switch 13, conductors 53 and 3ft, to the contact member 32, and, therefore, energizes the updirection switch 1 in exactly the manner it would be energized itt' the ear switch CS had been actuated to that position. In this event, the elevator motor EM is energized in exactly the manner hereinbefore described, and the car C continues its upward movement.

lV hen the car C reaches the position directly opposite the floor landing, the cam member is actuated to its innermost or fully-closed position, as determined by the stop member 10 which is shown by the dotted outline in Fig. 1.

It will be readily understoodthat, when the cam member 15 is in this latter position, the switch 13 is opened, thus deenergizing the updirection switch 1, and, as the car is moving slowly, it will be brought to rest directly opposite the loor landing.

In the event that the car C over-runs the floor landing, the lower end of the cam member 15 immediately engages the roller 19 of the switch 1-/1 and actuates it to its closed position, which is equivalent to operating the f car switch CS to the right, as viewed in the drawing, which energizes the down-direction switch 2, through a circuit extending from the line conductor L1, conductors 29 and 51, switch 14, conductors 54 and 55, limit switch V56, conductor 57, operating coil of the updirection switch 2 and conductors 5S and 39, to the line conductor L2. The closure of the 11p-direction switch 2 establishes an energizing circuit for the'generator shunt iield winding GF of opposite polarity, which causes the elevator motor EM to operate in the reverse direction to automatically bring the car C back to the desired oor level.

It will be readily understood that the levelling device 12 operates automatically to maintain the car C at the desired floor level, regardless of any variation of loading which may occur, since removing large loads from the car C will allow the cable Ca to contract and thereby bring the roller 19 into engagement with the cam member 15 and loading the car C stretches the cable Ca to bring the roller 1S into engagement with the upper end of the car member 15. In either event, automatically operating the elevator motor EM in the proper direction, as hereinbefore described, returns the carC to its initial position.

It will be noted that, with the system described in detail in the foregoing paragraphs, the levelling .operation of the elevator car may be simply and automatically controlled without employing. the usual more` expensive and complicated systems of levelling control. Since it is the usual practice to provide for decelerating the elevator car beforel bringing it to a complete stop, it is evident that this system may be readily utilized for both high-speed and low-speed elevators.

`Whilc I have shown and described a particular embodiment of my invention, it will be understood by those skilled in the art that changes and modifications may be made wit-hin the scope of the invention and I, therefore, aim in the appended claims to cover all such changes and modifications that Afall within the true spirit and scope of my invention.

I claim as my invention: f

1. In an elevator control system, an elevator ope able in a hatchway past a floor, a door for said hatchwa-y at said floor, motive means for the elevator, means for controlling the movements of the elevator, normally ineffective means operable in correspondence with movements of said elevator for causing said elevator to move to a position level with said floor, and means operable by opening said doorfor rendering said last named means effective.

2. In an elevator control system, an elevator operable in a hatchway past a Hoor, a door for said hatchwa-y at said floor, motive means for the elevator. means for controlling the movements of the elevator, normally ineffective means carried by the elevator disposed to become operable in accordance with the movements of the elevator to institute a levelling operation, and means dependent for operation by the movement of the door for rendering said last named means effective.

3. In an elevator control system, an elevator operable in a hatchway past a loor, a door for said hatchway at said oor, motive means for the elevator, means for lcontrolling the movements of the elevator, means including two relatively movable (1o-operating elements operable in correspondence with movements of said elevator for causing said elevator to move to a position level with said floor, means stationarily mounting one ot said elements adjacent said floor, means mounting the other of said elements for movement with said elevator, and means enl iageable by said door when in the closed position for moving said elements out of .cooperative relation.

4.In an elevator control system, in combinatlon an elevator operable 1n a hatchway past a floor, a door for said hatchway at said tioor, motive means for the elevator, means for controlling the movements of the elevator, and means for controlling the motive means to institute a levelling operation ot' the elevator, said means comprising a switch carried by the elevator, a member hingedly mounted inthe hatchway for actuating said switch, and means responsive to the opening of the hatchway door for positioning the switch actuating member so as to engage said switch.

5. In an elevator control system, in combination, an elevator operable in a hatchway past a floor, a door for said hatchway at said Hoor, motive means for the elevator, means for controlling the movements of the elevator, and means for controlling the motive means to instltute a levelling operation of .the elevator, said means comprising a switch carried by the elevator, a member hingedly mounted in the hatchway for actuating said switch, means carried by said door for maintaining said hingedly mounted member out of engagement with said switch when said door is closed.

' 6. In an elevator control system, in combination, an elevator operable in a hatchway past a floor, a door for said hatchway at said floor, motive means for the elevator and means for instituting a levelling operation, said means comprising a member secured to the elevator and a hingedly mounted member secured to the hatchway disposed to co- A operate mechanically with the member semember comprising a pivotally mounted cured to the elevator when the hatchway door is in the open position.

7. In an elevator control system, in combination, an elevator operable in a hatchway past a floor, a door for said hatchwa)7 at said Hoor, motive means for the elevator and means `for instituting a levelling operation, said means comprising a cam actuated switch carried by the elevator, a flexibly mounted member apart from the elevator and controlled by the position of the hatchway door and a cam member associated therewith disposed to engage said switch when the elevator is within a predetermined distance from said floor.

8. In an elevator control system, in combination, an elevator operable in a hatchway past a floor, a door for said hatchway at said ioor, motive means for the elevator, and means'for instituting a levelling operation, said means comprising a cam actuated switch secured to the elevator, a cam member disposed within the hatchway for actuating said switch, and means for supporting said cam member, a spring for maintaining the cam member in switch engaging position and a member disposed to cooperate with the hatchway door to move said member out of switch engaging position when the door is in a closed position.

9. In a control system for elevators operating in a hatchway provided with .doors atl the floor levels, in combination, a motor for operating the elevator, control switches for the motor, a master switch for controlling the movements of the elevator, additional normally ineffective means for also controlling the motor to automatically position the elevator levelwith that floor, and means operably responsive to movement of said hatchway door at any floor for rendering said additional means effective.

10. In a control system for elevators oper- Aating in a hatchway provided with doors at the floor levels, in combination, a motor for operating the elevator, means for controllmg the operation of the motor, said motor control means comprising a switch for starting and stopping the elevator at a point near the desired floor level and an auxiliary switch controlled by the movement of the hatchway door for automatically positioning the elevator level with said floor.

11. In a control system for elevators operating in a. hatchway provided with doors at the several floor levels, in combination, a motor for operating the elevator, means for controlling the operation of the motor, said motor control means comprising a switch for starting said elevator and stopping the elevator near the desired floor level and an auxiliary control switch operable only when the elevator is Within a certain predetermined distance from the desired landing floor level to institute a levelling operation, said switch being controlled by theopening and closing of the hatchway door.

' 12. In an elevator control system, in combination, an elevator operable in a hatchway past a floor, a door for said hatchway at said floor, .motive means for the elevator, means operable in correspondence with movement of the elevator for causing said elevator to stop level with said floor comprising means delining-a levelling zone adjacent said floor and means carried by the elevator for co-operation therewith, said zone defining means being movable from a position out of possible co-operation with said car carried means to a position of possible co-operation with said car carried means, and means operated by the opening and closing of said door for moving said zone defining means from one position to another.

13. In an elevator control system, in combination, an elevator operable in a hatchway past a floor, motive means for the elevator, means for controlling the movements of said elevator, means for compensatin for variations in the positioning of said e evator at a Hoor level under variations in loading comprising a switch member and a co-operating switch actuating member, one of said members being movable with the elevator and the other being stationary, and means controlled by the open and closed position of said door for moving said stationary member into and out of engagement, respectively, with said movable member.

14. In an elevator control system, in combination, an elevator operable in a'hatchway past a iloor, a door for said hatchway at said iioor, motive means for the elevator, means for controlling the movements of the elcvator, and means for instituting a levelling operation of the elevator, said means comprising switches with outwardly extending actuating arms carried by the elevator, a movable cam member in the hatchway disposed to engage the switch actuating arms when the elevator is within a predetermined distance RAY P, HIGBEE.

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