WO2024183880A1

WO2024183880A1 - Elevator safety system, elevator system and method for limiting elevator car travel path

Info

Publication number: WO2024183880A1
Application number: PCT/EP2023/055582
Authority: WO
Inventors: Ari Kattainen; Juha-Matti Aitamurto
Original assignee: Kone Corporation
Priority date: 2023-03-06
Filing date: 2023-03-06
Publication date: 2024-09-12

Abstract

An elevator safety system (120) comprising: a measurement system (20) configured to provide an indication of position of an elevator car (10) in an elevator shaft (1); a controller (50), configured: to determine presence of the elevator car at a lower end of the elevator shaft below a final limit of normal elevator operation (21) or at an upper end of the elevator shaft above a final limit of normal elevator operation; and in case presence of the car (10) below, or respectively above, the final limit of normal elevator operation (21), to generate a stopping command (52') to arrest movement of the car (10) if car movement fulfils at least one predefined stopping criteria. An elevator system (100) comprising the safety system (120). A method for limiting elevator car travel path in an elevator system.

Description

ELEVATOR SAFETY SYSTEM, ELEVATOR SYSTEM AND METHOD FOR LIMITING ELEVATOR CAR TRAVEL PATH

FIELD OF THE INVENTION

The invention relates to an elevator safety system, an elevator system and a method for limiting elevator car travel path. The elevator is preferably an elevator for transporting passengers and/or goods.

BACKGROUND OF THE INVENTION

An elevator may comprise an elevator car and a hoisting machinery operable to drive the car in an elevator shaft, to transfer passengers and/or cargo between landings. The hoisting machinery may comprise an electrical motor for driving the car, as well as hoisting machinery brakes configured to apply to a traction sheave or a rotating axis of the hoisting machinery, to stop movement of the car or hold the car standstill at a landing in the shaft.

Electromechanical brakes are triggered by an elevator safety system in some predetermined situations, such as in an overspeed situation of the car, or in case the elevator car passes the bottom floor of the bottom landing and arrives at a final limit switch below the bottom landing. The final limit switch sets a limit for movement of the car towards a bottom terminal of the elevator shaft including a safety buffer. The final limit switch is an electric safety device, which interrupts a safety chain of the elevator when the car arrives at the final limit switch. Interrupting the safety chain initiates de-energizing of the hoisting machinery motor and applying of the hoisting machinery brakes to stop movement of the elevator car.

Below the final limit switch there is still the safety buffer. Remaining kinetic energy of the car is absorbed by a stroke of the buffer, such that the car stops in any case before hitting the shaft bottom.

Therefore, a common solution to limit elevator car travel path at the bottom terminal is to have following distances and functions: a vertical distance clearance between the bottom landing and the final limit switch; a clearance between a final limit switch operation point and car contact with the buffer; and the car buffer stroke.

The elevator may also have hoisting ropes running via the traction sheave of the hoisting machinery. Recently a new kind of coated hoisting ropes have been introduced. These may be round ropes with a high-friction coating, or substantially flat belts with high-friction coating, such as a polyurethane coating. Load-carrying parts of the coated ropes/belts may be steel cords and/or they can be made of synthetic fibers, such as glass fibers or carbon fibers, for example.

As discussed above, the final limit switch initiates de-energizing of the hoisting machinery motor before the car arrives at the safety buffer. Therefore, the prior art final limit switch must be positioned such that operation of the final limit switch prevents the counterweight from rising when the car is stalled to the buffer, as well as wear-out of the traction sheave and the coated ropes - in case the traction sheave would still rotate when the car is on the buffer. All this leads to the outcome that the overall vertical length under the bottom floor, which is defined by the final limit switch clearance and the buffer stroke, is often rather high counting up to approximately 120-140 mm in an elevator with 1 m/s rated speed, for example.

There is a need for reducing the overall vertical length under the bottom landing. On the other hand, there is a general aim to design spaceefficient elevator systems, to utilize the built space efficiently.

SUMMARY OF THE INVENTION

The objective of the invention is to solve one or more of the aforementioned problems by introducing an elevator safety system, an elevator system, and a method for limiting elevator car travel path, which make it possible to reduce the above-mentioned overall vertical length under the bottom landing. The invention provides solutions relating to limiting elevator car travel path at the final terminals of the elevator shaft.

The elevator safety system according to the invention is defined in claim 1.

The elevator system according to the invention is defined in claim 14. The method for limiting elevator car travel path is defined in claim 17. Preferable further embodiments of the invention are introduced in the following and in the appended dependent claims, which further embodiments can be combined individually or in any combination.

An exemplary elevator system comprises an elevator car and an elevator shaft. The elevator car transfers passengers and/or cargo in the elevator shaft between landings in the shaft. The elevator system also comprises an elevator hoisting machinery that generates driving torque to drive the car. Movement of the car is managed by an elevator control, which generates control commands needed to drive the hoisting machinery.

The elevator system comprises a measurement system configured to provide an indication of the elevator car position and/or speed in the shaft. According to an embodiment, such a measurement system comprises e.g. one or more of a motor encoder, a car encoder, a door zone sensor, a measurement strip extending in the shaft next to elevator car trajectory etc. According to an embodiment, such indication is in more detail information about a bottom floor area, and/or the location of the elevator car in the bottom floor area, and/or the speed of the elevator car in the bottom floor area, and time spent in the bottom floor area.

According to an embodiment, the hoisting machinery comprises machinery brakes to apply to a traction sheave or a rotating axis of the hoisting machinery, to stop movement of the car or hold the car standstill at a landing in the shaft.

Further, the elevator system comprises a safety system. The safety system comprises a programmable electronic safety controller, which receives information from the measurement system such that it can monitor the elevator car position and/or speed in the shaft.

According to an embodiment, the safety controller comprises an overspeed monitor which generates an emergency stopping command in case elevator car speed exceeds a predefined limit value.

According to an embodiment, the predefined second speed limit value is represented by a curve, that decreases in accordance with elevator car position towards the bottom landing, such that the machinery brakes are triggered already at lower car speed in the proximity of the bottom terminal during normal elevator operation, to reduce possible buffer impact. According to an embodiment, the predefined second speed limit value curve is a speed limitation curve having a profile at a distance from an elevator normal operation speed curve.

According to an embodiment, at upper and lower ends of the elevator movement path in the shaft during normal elevator operation, just above and below the respective top and bottom landings there are final limits memorized in the safety controller, which limits define extreme position limits for normal elevator operation, i.e. extreme limits for elevator car movement during normal elevator operation. Additionally or alternatively, the final limits may be implemented in the form of physical final limit switches arranged at upper and/or lower ends of the elevator movement path, respectively, and status information of said switches may be taken to the safety controller.

The safety controller monitors presence of the car at the lower end of the shaft below the final limit of normal elevator operation, and it generates a stopping command to the machinery/machinery brakes to arrest movement of the car, if car movement below the final limit fulfils at least one predefined stopping criteria. The term “final limit of normal elevator operation” refers to a position limit, which defines an extreme limit for elevator car movement during normal elevator operation. In other words, normal operation of the elevator is not possible below the final limit of normal elevator operation at the lower end of the elevator shaft or above the final limit at the upper end of the elevator shaft. In those areas however a special, strictly restricted operation is possible, wherein a stopping command to arrest movement of the car is generated, if car movement fulfils at least one predefined stopping criteria. Thus, the safety controller does not cause any safety shutdown of the elevator and force the car operation to be stopped in response to passing of the limit of the elevator normal elevator operation, but instead allows movement of the car closer to the movement area end. The elevator operation is possible outside the area of normal elevator operation - without interrupting the safety chain of the elevator - at a lower speed and for a short operating time, and from this condition it is possible to return normal elevator operation. In prior art solutions such monitoring is not made behind a final limit switch. In prior art solutions the final limit switch sets a limit for movement and interrupts the safety chain of the elevator when the car arrives at the final limit switch resulting to stopping operation of the elevator car.

According to an embodiment, the predefined stopping criteria is elevator running time below the final limit. In this case the safety controller generates a stopping command if the running time exceeds a predefined time limit.

According to an embodiment, additionally or alternatively, the predefined stopping criteria is elevator car speed, and the safety controller generates a stopping command if car speed exceeds a predefined speed limit value.

By means of the invention the car operating range can be extended below the final limit of normal elevator operation, such that recovery operation of the car is still possible even after the car has reached and passed the final limit of normal elevator operation, in which case normal elevator operation isn’t possible any more.

According to an embodiment, the above mentioned predefined stopping criteria of the safety controller are selected such that a risk of a rising counterweight, as well as a risk of wear of rope coating can be avoided, while the vertical length of the shaft pit below the bottom landing can be reduced.

By means of the invention a space-efficient elevator system may be achieved with the overall vertical length at the smallest of about 20 mm below the bottom landing.

A further advantage of the invention is that an elevator system may be achieved with a pit depth of approximately 150 mm below the bottom landing. In practice, the elevator shaft pit may only be a recess in the floor.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will in the following be described in greater detail by means of preferred embodiments with reference to the attached drawings, in which:

Figure 1 shows an elevator system provided with a safety system,

Figure 2 shows a block diagram of some elements of the elevator system, and

Figure 3 shows an example of an elevator car speed represented by a curve.

DETAILED DESCRIPTION

Figure 1 schematically illustrates some aspects of an elevator system 100 comprising an elevator car 10 and a hoisting machinery 5 operable to drive the car 10 in an elevator shaft 1 , to transfer passengers and/or cargo between landing floors 32 of landings 30.

In Figure 1 the car 1 is shown at the lowest point of the car movement path, in the shaft at a bottom landing 30 in normal elevator operation. A shaft pit 2 with pit depth 2’ extends vertically below the bottom landing. Safety buffers 3 are mounted in the pit 2.

The exemplary elevator system 100 comprises an elevator control 110, which generates control commands 5’ needed to drive the hoisting machinery 5 and manages the movement of the car 10. The hoisting machinery 5 comprises an electrical motor 51 for driving the car 10, as well as hoisting machinery brakes 52 configured to apply to a traction sheave 53 or a rotating axis of the hoisting machinery, to stop movement of the car or hold the car standstill at a landing 30 in the shaft 1. More generally, the elevator system comprises at least one mechanical brake to stop movement of the car or hold the car standstill in the shaft 1 . The elevator system in Figure 1 has hoisting ropes 6 supporting the car 10, running via the traction sheave 53, and connected to a counterweight 7.

The car 10 is provided with a car door 11 and a car floor 12. The car door 11 comprises a door that may be moved between a closed position and an open position. The car door 11 may be kept locked while the car 10 is moving, unlocked upon the car 10 entering a landing zone located at and close to a landing 30 provided with a landing floor 32 and opened upon the car 10 stopping at the landing 30. The car door 11 may be closed before the car 10 leaves the landing 30 and locked upon the car 10 exiting the landing zone. The car 10 is provided with a door operator 13 connected to the car door 11 for temporarily coupling the car door 11 to a landing door 31 provided at each landing 30 when the car 10 resides within the landing zone of the landing 30 such that the landing door 31 moves between a closed position and an open position together with the car door 11 , thereby allowing passengers to move between the landing floor 32 and the car 10 when the car 10 is at the landing 30 while preventing the passengers from entering the shaft 1 when the elevator car 10 is not at the landing 30.

The elevator system comprises a measurement system 20 configured to provide an indication of the elevator car 10 position in the shaft 1 . The measurement system 20 may comprise e.g. one or more of: a motor encoder; a car encoder; a door zone sensor e.g. providing position information of the elevator car 10 in the vicinity of each landing floor 32; a measurement strip extending in the shaft next to elevator car trajectory such as an optically or magnetically readable tape extending in the shaft.

Figure 2 shows a block diagram of some elements of the elevator system 100.

The elevator system 100 comprises a safety system 120. The safety system comprises a programmable electronic safety controller 50 which receives information 20’ from the measurement system 20 such that it can monitor the elevator car 10 position and/or speed in the shaft 1 . According to an embodiment the safety controller 50 is incorporated in a main safety controller of the elevator system, where the function limiting the travel path of the car may be implemented with position, time, and speed limits.

According to another embodiment the safety controller 50 is located in a drive controller of the elevator system.

At least one mechanical brake 52 of the elevator system causing the car 10 to stop in the shaft 10, for example the hoisting machinery brakes 52, is triggered by the elevator safety system 120 in some predetermined situations.

According to an embodiment, the safety system 120 comprises an overspeed monitor 60 configured to generate an emergency stopping command 52’ in case elevator car speed C exceeds a predefined second speed limit value L during normal elevator operation, wherein the overspeed monitor 60 has at least two different position-dependent second speed limit values L1 at different points in the shaft 1 , respectively, such that said second speed limit values decrease towards the bottom landing. The stopping command 52’ causes the at least one mechanical brake to be locked and the car 10 to stop in the shaft 10.

According to an embodiment, the safety controller 50 comprises the overspeed monitor 60 which generates an emergency stopping command 52’ in case elevator car speed exceeds a predefined second speed limit value set for car speed during normal elevator operation.

An example of the elevator car speed is represented by a curve C, and an example of the predefined second speed limit value is shown as a curve L, L1 , L2 shown in Figure 3, where the horizontal axis P indicates position, and the vertical axis S indicates speed.

According to an embodiment, the predefined second speed limit value is represented by the curve L which decreases in accordance with elevator car 10 position towards the bottom landing 30, such that the at least one mechanical brake 52 is triggered already at lower car speed L1 in the proximity of the final limit 21 during normal elevator operation, to reduce possible impact on the buffer 3.

According to an example, a final velocity L1 when approaching the final limit 21 is limited to an example value 0,3 m/s. Thus, the prior art final limit switch function is replaced by a time- and speed-limited operating range. With an example buffer 3 compression of 10 mm and the example speed value of 0.3 m/s an example average deceleration is 0.5 gn or 4.5 m/s² which is well below the standard limit of 1 gn. According to the example, if the location of the elevator car 10 is more than 10 mm below the floor 32, the motor 51 is only allowed to be activated for a short time at a time, e.g. 1-2 seconds.

According to an example, when the buffer 3 is placed e.g. 15 mm below the lowest floor 32, one to two seconds are sufficient to set the accuracy of the car 10 up from the buffer 3 if it has been pushed there during loading due to a sudden load increase.

According to an embodiment, the safety controller 50 decreases the car speed the closer to the final limit 21 the car is moving.

According to an embodiment, the safety controller 50 decreases the second speed C the closer to the final limit 21 the car is moving.

According to an embodiment, the safety controller 50 decreases the second speed until a final speed limit in the proximity of the bottom landing 30 is achieved.

According to an embodiment, the car 10 operating range below the final limit 21 extends to the location 22 of the safety buffer 3 located in the pit 2.

At upper and lower ends of the elevator movement path in the shaft 1 during normal elevator operation, just above and below the respective top and bottom landings 30 there are final limits 21 memorized in a memory in the safety controller 50, which memorized final limits 21 according to an embodiment define extreme position limits for normal elevator operation, i.e. extreme limits for elevator car movement during normal elevator operation.

The safety controller 50 monitors presence of the car 10 at the lower end of the shaft 1 behind, i.e. outside, the final limit 21 of normal elevator operation, in other words below the bottom final limit 21 of normal elevator operation and/or above a top final limit of normal elevator operation. The safety controller 50 generates a stopping command 52’ to the machinery brakes 52 to arrest movement of the car 10 if car movement behind the final limit 21 fulfils at least one predefined stopping criteria.

According to an embodiment, the predefined stopping criteria is elevator car 10 running time behind the final limit 21. In this case the safety controller 50 generates a stopping command 52’ if the running time exceeds a predefined time limit value.

According to an embodiment, additionally or alternatively, the predefined stopping criteria is elevator car speed L2 below the bottom final limit 21 , and the safety controller 50 generates a stopping command 52’ if the car speed exceeds a predefined speed limit value. According to an embodiment, additionally or alternatively, the predefined stopping criteria is elevator car speed above the top final limit, and the safety controller 50 generates a stopping command 52’ if the car speed exceeds a predefined speed limit value.

According to an embodiment, the above mentioned predefined stopping criteria of the safety controller 50 are selected such that a risk of a rising counterweight 7, as well as a risk of wear of traction sheave 53 or rope 6 coating due to rope sliding can be avoided, while the vertical length 2’ of the shaft pit 2 below the bottom landing 30, 32 can be reduced.

The method for limiting elevator car travel path in an elevator system as described above comprises: providing indication of position of the elevator car 10 in the elevator shaft 1 ; determining presence of the elevator car at a lower end of elevator shaft below a final limit of normal elevator operation 21 or at an upper end of elevator shaft above a final limit of normal elevator operation, and in case presence of the car 10 below, or respectively above, the final limit of normal elevator operation 21 , generating a stopping command 52’ to arrest movement of the car 10 if car movement fulfils at least one predefined stopping criteria.

According to an embodiment, the predefined stopping criteria is elevator car 10 running time behind the final limit 21 , and the controller 50 is generating a stopping command 52’ if the running time exceeds a predefined time limit value.

According to an embodiment, the predefined stopping criteria is elevator car 10 speed C, and the controller 50 is generating a stopping command 52’ if the elevator car speed C exceeds a predefined speed limit value L2.

The use of the invention is not limited to the embodiments disclosed in the figures. It will be obvious to a person skilled in the art that, as the technology advances, the inventive concept can be implemented in various ways. The invention and its embodiments are not limited to the examples described above but may vary within the scope of the claims.

Claims

1 . An elevator safety system (120) comprising a measurement system (20) configured to provide an indication of position of an elevator car (10) in an elevator shaft (1 ); a controller (50), configured: to determine presence of the elevator car at a lower end of the elevator shaft below a final limit of normal elevator operation (21 ) or at an upper end of the elevator shaft above a final limit of normal elevator operation, and in case presence of the car (10) below, or respectively above, the final limit of normal elevator operation (21 ), to generate a stopping command (52’) to arrest movement of the car (10) if car movement fulfils at least one predefined stopping criteria.

2. The elevator safety system according to claim 1 , wherein the predefined stopping criteria is elevator car (10) running time behind the final limit (21 ), and wherein the controller (50) is configured to generate a stopping command (52’) if the running time exceeds a predefined time limit value.

3. The elevator safety system according to any of preceding claims, wherein the predefined stopping criteria is elevator car (10) speed (C), and wherein the controller (50) is configured to generate a stopping command (52’) if the elevator car speed (C) exceeds a predefined speed limit value (L, L1 , L2).

4. The elevator safety system according any of preceding claims, wherein the measurement system (20) comprises one or more of: a motor encoder, a car encoder, a door zone sensor, a measurement strip extending in the shaft next to elevator car trajectory.

5. The elevator safety system according to any of preceding claims, wherein the controller (50), such as a programmable electronic safety controller, is configured to receive information from the measurement system (20) to monitor the elevator car (10) position and/or speed (C) in the shaft (1 ).

6. The elevator safety system according to any of preceding claims, wherein the car (10) operating range below the final limit (21 ) extends to a location (22) of a safety buffer (3) located in the pit (2).

7. The elevator safety system according to any of preceding claims, comprising an overspeed monitor (60) configured to generate the stopping command (52’) in case elevator car speed (C) exceeds a predefined second speed limit value (L) set for car speed during normal elevator operation.

8. The elevator safety system according to preceding claim, wherein the safety controller (50) comprises the overspeed monitor (60).

9. The elevator safety system according to claim 7 or 8, wherein the predefined second speed limit value is represented by a curve (C) which decreases in accordance with elevator car (10) position towards the bottom landing (30), such that at least one mechanical brake (52) comprised by the elevator is triggered already at lower car speed in the proximity of the final limit (21 ) during normal elevator operation.

10. The elevator safety system according to any of claims 7 - 9, wherein the controller (50) is configured to decrease the second speed limit until a final speed limit in the proximity of the bottom landing (30) is achieved.

11 . The elevator safety system according to any of preceding claims, wherein upper and lower final limits (21 ) define extreme limits for normal elevator operation, preferably extreme limits for elevator car movement during normal elevator operation.

12. The elevator safety system according to any of preceding claims, wherein at least one predefined stopping criteria is selected such that conditions of a rising counterweight (7) of wear of traction sheave or rope (6) coating can be avoided.

13. The elevator safety system according to any of preceding claims, wherein the controller (50) comprises at least one memorized final limit of normal elevator operation (21 ).

14. An elevator system (100) comprising an elevator shaft (1 ) and an elevator car (10) configured to transfer passengers and/or cargo in the elevator shaft between landing floors (32), and at least one mechanical brake (52) configured to arrest movement of an elevator car (10) responsive to a stopping command (52’), wherein the elevator system comprises a safety system (120) according to any of preceding claims.

15. The elevator system according to preceding claim, comprising a hoisting machinery (5) operable to drive the elevator car (10).

16. The elevator system according to preceding claim, wherein the at least one mechanical brake comprises a machinery brake (52) of the hoisting machinery (5).

17. A method for limiting travel path of an elevator car (10) in an elevator system (100) according to any of claims 14 to 16, the method comprising: providing indication of position of the elevator car (10) in the elevator shaft (1 ); determining presence of the elevator car at a lower end of elevator shaft below a final limit of normal elevator operation (21 ) or at an upper end of elevator shaft above a final limit of normal elevator operation; and in case presence of the car (10) below, or respectively above, the final limit of normal elevator operation (21 ), generating a stopping command (52’) to arrest movement of the car (10) if car movement fulfils at least one predefined stopping criteria.