Elevator control system

Abstract

An emergency control system is provided for an elevator installation which responds automatically to a power failure, low voltage condition, loss of phase, or the like, to move the elevator to a reference floor, and then to open the elevator doors and hold them open to permit passengers to leave the elevator. The system of the invention includes a battery activated source of power which is maintained charged when the elevator is in its normal operating condition. In the event of a power failure, the system automatically switches power from the battery activated source to appropriate controls in the elevator control system so as to move the elevator car automatically to a reference floor, and then automatically to open the elevator doors at the reference floor to permit the passengers to leave.

Description

BACKGROUND OF THE INVENTION

One of the most common problems in the elevator art is that of electric power failure. When such a power failure occurs in present day elevator systems, the elevator car comes to an abrupt stop, and the passengers are held locked in the car. An emergency button and/or auxiliary telephone within the car are the only present day means available for notifying those on the outside that an emergency exists.

Because of the increasing frequency of power blackouts, a real problem arises, especially within urban areas where elevators are mandatory for apartment and office buildings, stores, hospitals, homes for the aged, garages, warehouses, factories, and so on. A necessity has arisen, therefore, for the development of a satisfactory emergency power control system which will provide a supplementary emergency power to move the elevator to a reference floor, and then to open the elevator doors, in the event of a power failure, or other malfunction of the normal elevator control equipment.

The emergency elevator control system of the present invention, in the embodiment to be described, is advantageous in that it may be easily installed in conjunction with a present day elevator control system, and it does not interfere in any way with the safety features incorporated into the normal control system. The system to be described provides lighting in the elevator car under the emergency conditions, and a controlled safe moving of the elevator car to a reference floor. The emergency control system also provides means for opening the elevator car and hallway hatch doors at the reference floor, thereby permitting the passengers to move safely out of the car and into the hallway. The control may be such that the emergency lighting in the elevator car remains on after the elevator and hatch doors have been opened, so as to provide light in the darkened hallways and corridors of the building.

Specifically, the present invention provides an improved and relatively simple system which can be incorporated into the controls of existing elevator systems to provide a simple and expeditious means for permitting passengers to leave an elevator, safely and without any appreciable time delay, should a power failure, or other malfunction occur.

The emergency power system of the invention will be described herein in conjunction with an hydraulic type of elevator control system. However, it will become evident as the description proceeds that the emergency control system of the invention may be used in conjunction with a wide variety of different types of hydraulically and electrically controlled elevator systems.

In the hydraulic elevator system to be described, the emergency control provides for the car to be lowered slowly to the main floor, or other reference floor, should an emergency condition occur. This is achieved by controlling the valve which slowly bleeds the oil in the hydraulic cylinder back to the reservoir, so that the ram will move slowly downwardly, permitting the elevator car slowly to descend. The control for the hydraulic system may be alternating electric current, or direct current, depending upon the type of electrically operated valves used in the system. In the embodiment to be described, a direct current control is used, although it may easily be replaced by an alternating current control if so required. Direct current voltages may be used to control the alternating current actuating coils of the various valves in an alternating current control system by selecting predetermined direct current "pick" voltages for introduction to the various alternating current actuating coils.

When the elevator is of the electric type, the control may be such that the car is either raised or lowered to the next adjacent floor. This raising or lowering of the car may be determined by the load in the elevator car, the car being raised when the load is less than the counterweighting load, and lowered when the load is greater than the counterweighting load. The control of the electrically operated elevators is usually coupled to the holding brake, with the coil of the holding brake being picked to a slip condition so that the elevator may move up or down to the next floor, at which point the brake is released and closed. Again the emergency control system may be either direct current or alternating current, and it may be used in conjunction with brakes having direct current actuating coils or alternating current actuating coils.

The emergency control system of the invention, in the embodiment to be described, is powered by a reliable, constantly charged direct current battery source. The emergency control system senses an emergency condition, and immediately switches to the direct current battery source. The system protects itself against any off-on condition, and, as previously noted, it recognizes key safety circuits incorporated into the usual elevator control system.

When the emergency control system to be described is activated, it immediately energizes one or more emergency lights in the elevator car so as to restore illumination within the car. It may also energize a light in a control panel to illuminate a message notifying the passengers that the elevator is now under emergency control. The system to be described then activates an appropriate control in the elevator control system to cause the elevator car to be lowered to the main floor at a slow rate of speed, and then to cause the elevator and hatchway doors to be opened, and to be held open.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic perspective representation of an hydraulic elevator installation which may incorporate the emergency control system of the present invention;

FIG. 2 is a block diagram of the hydraulic elevator control installation of FIG. 1;

FIG. 3 is a schematic diagram, partly in block form, showing the controls for the elevator installation of FIGS. 1 and 2, and also showing an emergency control system embodying the present invention in one of its aspects;

FIG. 4 is a circuit diagram of an inverter included in the system of FIG. 3; and

FIG. 5 is a circuit diagram of a battery charger included in the system of FIG. 3.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT

In the representation of FIG. 1, an elevator car 10 is supported on guard rails 12 in a vertical elevator well, or pit. The car is moved up and down in the well by means of an hydraulic ram 16 which extends into an hydraulic cylinder or casing 18. Spring buffers 20 are provided at the bottom of the well. A cross head safety switch 22 is mounted on the top of the car 10, and it is operated when the car moves to its upper limit of travel. A pit safety switch 24 is mounted near the bottom of the well, and it is operated when the car is at its lower limit of travel. These safety switches assure that the car 10, under no conditions, will be driven beyond its upper or lower limits. A door safety switch 30 is mounted on the car 10, and this switch is operated when the doors of the car are open to prevent movement of the car until the doors are closed. The elevator is controlled by a power unit and hydraulic controller 32.

The representation of FIG. 2 illustrates the manner in which the elevator hydraulic control system 32 controls the ram 16 by pumping hydraulic fluid into the casing 18 to raise the car 10, and by subsequently bleeding the hydraulic fluid from the casing to lower the car. The hydraulic fluid is pumped from an oil reservoir 40 in the controller 32 by means of a pump 42 which is driven by an electric motor 44. The oil is pumped through a valve 46, and appropriate control of the valve 46 causes the fluid to be bled back to the reservoir 40 for the controlled descent of the car 10. The motor 44 and valve 46 are controlled by a normal elevator control system represented by the block 48. Three-phase alternating current power is supplied to the motor 44 through the control system 48. The emergency control system of the invention is represented by the block 50, and one embodiment of the emergency control system is shown in more detail in the diagram of FIG. 3. A portion of the conventional control system of a typical hydraulically controlled elevator, such as the installation of FIGS. 1 and 2, is also shown in FIG. 3.

The three-phase power line is connected through usual breaker contacts 100 to the pump motor 44. A transformer T1 is connected across one of the phases of the three-phase AC power line, and the transformer develops 115 volts, for example, across its secondary. The secondary of the transformer is connected through the normally-closed pit safety switch 24 and cross head safety switch 22 and emergency switch 50 to a lead 52, and the secondary is directly connected to a lead 54. The various operating controls for the elevator are connected between the leads 52 and 54.

For example, the junction of the switches 22 and 50 is connected to a pair of down relay contacts DO, and to a pair of level-down relay contacts LD. The DO relay contacts are connected to a pair of down-auxiliary relay contacts DX which, in turn, are connected to the energizing coil of a down pilot relay E, whose other terminal is connected to the lead 54. The relay contacts DX and LD are also connected through a pair of normally-closed relay contacts A3 to the actuating coil of the down-slow valve 46a, the other terminal of which is connected to the lead 54. These contacts are also connected through a pair of relay contacts HSI to the actuating coil of the down-fast valve 46b which, in turn, is also connected to the lead 54.

The lead 52 is also connected through a pair of normallyclosed relay contacts A3 to the movable arm of a second cross head switch 22a which operates in addition to the cross head safety switch 22. The normally-open contact of the cross head section 22a is connected back to the lead 52, and a normally-closed contact is connected to a normally-closed pit safety switch 24a which operates in addition to the pit safety switch 24.

The cross head switch 22a includes a second movable arm which is connected through a first floor-level switch 56 to an emergency light 58; and which is also connected through a pair of hatch door contacts 60 to the door-open relay DO, to a car-door relay OR, and to a pair of normally-open relay contacts A1. The relay DO is also connected through a pair of up-holding relay contacts UA1 to the coil of an up-auxiliary relay UX. The aforesaid relay coils are all connected to the lead 54.

The lead 52 is also connected through a pair of normally-closed relay contacts A3, and through a door-open limit switch DOL to an open-door relay OD and to an open-limit relay OU. The relay OU is connected to the lead 54, and the relay OD is connected through a pair of a safety edge contacts SE to the lead 54.

The emergency system of the invention includes an alternating current power-sensing relay A1 which is normally energized, but becomes de-energized upon a loss of power, loss of voltage, or any other malfunction which affects the secondary voltage of the transformer T1. A battery-actuation relay A2 is connected in shunt with the relay A1, both the relays A1 and A2 being connected across the secondary of the transformer T1.

A phase-loss sensing relay PS is connected across the primary of the transformer T1 and across the other two phases of the three-phase AC power line. Relay PS is normally energized, but becomes de-energized upon a loss of phase.

A battery charger 62 is also connected across the secondary of the transformer T1. The circuitry of the battery charger will be discussed in conjunction with FIG. 5. A storage battery 64 is connected across the battery charger 62, and an inverter 66 is connected across the storage battery. The circuit details of the inverter 66 will be discussed in detail in conjunction with FIG. 4.

The positive terminal of the battery charger 62 and storage battery 64 is grounded, and is connected through a pair of normally-open relay contacts A2 to a pit-and-cab interlock relay B, a levelling relay AX, and a battery-transfer coil A3. The relay B is connected through a pair of normally-open relay contacts A3 to the pit switch 24a; the relay AX is connected through a pair of normally-open relay contacts A1 to the cross head switch 22a; and the battery transfer relay A3 is connected through a pair of normally-open contacts A1 to the level switch 56. The other terminals of the relays B, AX and A3 are connected through a pair of normally-open relay contacts A1 to the emergency light 58.

The negative output lead of the inverter 66 is connected through a pair of normally-closed relay contacts AX, and through a pair of normally-open relay contacts B and a pair of normally-open relay contacts A3, to the down-slow valve 46a. The positive terminal of the inverter 66 is connected to the lead 54.

The relays AX, B and A3 in the emergency control system shown in FIG. 3 are 24-volt direct current relays, and the battery 64 is a 24-volt battery. The inverter 66 in the illustrated embodiment produces a direct current output voltage of 48-volts direct current, which is sufficient to operate the actuating coil of the down-slow valve 46a and the relay coil DO, although these elements are designed for normal operation in the particular control system on 115-volts alternating current.

During normal operation of the elevator control system, both the relays A1 and A2 are energized, and the A1 contacts, shown closed in FIG. 3, are open, as are the A2 contacts shown closed in FIG. 3. Under these conditions the elevator is under the control of its normal control circuitry to move up to selected floors and down to selected floors.

The car 10 is caused to move upwardly by closing the breaker contacts 100 to energize the pump motor 44. The car is subsequently caused to move downwardly by energizing a relay HS1, which closes the HS1 contacts to open the down-fast valve 46b. When the car approaches a pre-selected floor, the down-level switch LD closes, and this causes the down-fast valve 46b to close and the down-slow valve 46a to open. Then, when the selected floor is reached, the switch LD opens to cause the down-slow valve 46a to close, and the car stops.

The various other controls shown in FIG. 3, apart from the emergency control system, are standard and need not be described in detail.

In the event of a power failure, the relays A1 and A2 becomes de-energized and all their normally-closed relay contacts assume the closed position shown in FIG. 3. Under these conditions the emergency light 58 is immediately illuminated. Also, the battery transfer relay A3 is now connected across the storage battery 64 by the closure of the relay contacts A2, and relay A3 becomes energized. The pit and cab interlock relay B is also energized by the closing of the relay contacts A3, so long as the pit switch 24a and, the cross head switch 22a, and the car door contacts 61 are all closed. Now, the down-slow valve 46a is connected across the inverter 66, and it opens to permit the car to descend slowly.

The descent continues until the first floor, or other reference floor, is reached, and the level switch 56 is closed. When the level switch 56 closes, the levelling relay AX becomes energized to break the connection to the down-slow valve A3, so that the car stops. The levelling relay AX also completes a circuit to the relay OD at this time so that the car and hatch doors are opened to permit the occupants of the car to escape. The switch DOL is a door-open limit switch, and it is closed when the doors are closed, as is the door edge safety switch SE.

The inverter 66, as shown in FIG. 4 may be a usual prior art solid state system. The illustrated inverter is capable of providing different output direct current voltages, and, in the illustrated embodiment, a 48-volt output voltage is used. The inverter is activated by the storage battery 64 which introduces a 24-volt direct current voltage across the input terminals 100.

The battery charger 62 is shown in circuit detail in FIG. 4, and it also may be a conventional solid state type of battery charger. The charger includes an integrated circuit of the type designated MC1723CG, as shown, and also incorporates a solid state full-wave rectifier designated MDA920-1 which is connected across the secondary of a transformer T4. The 115-volt alternating current input voltage from the transformer T1 of FIG. 3 is applied across the input terminals 200 of the circuit, and the 24-volt direct current charging voltage is developed across the output terminals 202.

The invention provides, therefore, an improved emergency control for an elevator which, in the event of power failure, asserts a secondary control on the elevator control system so as to move the car to a reference floor, and then to open the doors of the car to permit the occupants to escape.

It will be appreciated that although a particular embodiment of the invention has been shown and described, modifications may be made. It is intended in the following claims to cover the modification which come within the true spirit and scope of the invention.

Claims

What is claimed is:

1. In an elevator system which includes a car, and circuit means connected to a main source of electric energy and including a plurality of individual electrically-operated controls for controlling up and down movements of the car, and in which said circuit means includes a further individual control for opening the doors of the car when the car reaches a reference floor level; an emergency control system including: an auxiliary power source including a battery; first relay means coupled to said main source to be normally energized by electric power derived from said main source; first contact means controlled by said first relay means and connected to said auxiliary power source for connecting said auxiliary power source directly to a first one of said individual controls in said circuit means upon the de-energization of said first relay means so as to produce movement of the car to a reference floor level; second relay means; second contact means controlled by said first relay means to cause said second relay means to be energized by said auxiliary power source upon de-energization of said first relay means; and third contact means controlled by said second relay means to contact said auxiliary power source directly to said further individual control in said circuit means upon the energization of said second relay means to cause the doors of the car to open when the reference floor level is reached.

2. The combination defined in claim 1, and including a battery charging circuit coupled to said main source of electrical energy and connected to said battery for maintaining said battery in a charged condition.

3. The combination defined in claim 1, and which includes an inverter circuit included in said auxiliary power source for transferring the voltage of said battery to a different value, and in which said first contact directly connects the output of said inverter across said first control in said circuit means to produce movement of said car to a reference floor level.

4. The combination defined in claim 1, and which includes an emergency light connected in circuit with a second contact means of said first relay means to be energized upon the de-energization of said first relay means.

5. The combination defined in claim 1, and which includes fourth contact means controlled by said second relay means to disconnect said auxiliary power source from said first individual control in said circuit means when said second relay means is energized.

6. The combination defined in claim 1, in which said circuit means includes a level switch positioned to be actuated when the car reaches said reference floor level; and which includes a second relay means in circuit with said level switch and with said first contact means to be energized when said first relay means is de-energized and when said level switch is actuated, and second contact means controlled by said second relay means and directly connected to said first individual control in said circuit means to stop movement of the car when said second relay means is energized.

7. The combination defined in claim 6, in which said circuit means includes electrically-operated door control means, and third contact means controlled by said second relay means and connected in circuit with said door control means to cause said door means to open the doors of the car when said second relay means is energized.