Monitoring operating condition of automatic elevator door

Abstract

An arrangement and a method for monitoring the operational condition of an automatic door in an elevator, particularly a passenger and/or goods elevator, or in a building, the arrangement includes an automatic door which includes one or more door leaves, which slide horizontally in their location, a door operator, which includes a door motor and a door mechanism for moving the door leaf horizontally in its location, a closing device for closing the automatic door, a control system for the door operator for controlling the door motor, a device configured to define the operational condition of the closing device and the door mechanism of the automatic door, the device configured to define the operational condition of the closing device and the door mechanism of the automatic door includes a mechanism configured to determine the mechanical energy of the shaft in the door motor of the automatic door during an operating cycle.

Claims

1. An arrangement for monitoring the operational condition of an automatic door of an elevator, in particular of a passenger and/or goods elevator, or of a building, the arrangement comprising: an automatic door comprising one or more door leaves that slide in their location horizontally; a door operator comprising a door motor and a door mechanism for moving the door leaf in its location horizontally; a closing device for closing the automatic door; a control system of the door operator for controlling the door motor; and a device configured to define the operational condition of the closing device and the door mechanism of the automatic door, wherein the device configured to define the operational condition of the closing device and the door mechanism of the automatic door comprises a mechanism configured to determine mechanical energy of the shaft of the door motor of the automatic door during an operating cycle.

2. The arrangement of claim 1, wherein said mechanism configured to determine the mechanical energy of the shaft of the door motor of the automatic door comprises: a device configured to produce door state information during an operating cycle; and a device configured to determine mechanical power of the shaft of the door motor during an operating cycle.

3. The arrangement of claim 1, wherein said device configured to define the operational condition of the door mechanism and/or the closing device of the automatic door comprises a mechanism configured to determine the magnitude of the friction force and/or the amount of potential energy stored in the door mechanism, during an operating cycle.

4. The arrangement of claim 1, wherein said device configured to define the operational condition of the closing device and the door mechanism of the automatic door comprises a condition monitoring algorithm, which is implemented: in a control system of the door operator, or in an elevator control system, or in a separate measuring system, or in a local user interface, or in a remote user interface, or on a remote server.

5. The arrangement of claim 4, wherein the local user interface or the remote user interface of the automatic door is integrated to be part of the elevator control system.

6. The arrangement of claim 4, wherein said control system for the door operator is integrated to be part of the elevator control system.

7. The arrangement of claim 2, wherein said device configured to produce door state information of the automatic door during an operating cycle comprises: an encoder measuring the travel of the door, or switches of the door, which comprise a force limiting switch for door open and door closed, or door in a given position, or a tachometer measuring the velocity of the door motor, or an accelerometer measuring the acceleration, velocity or location of the door.

8. The arrangement of claim 1, wherein the door motor is a DC motor or an AC motor.

9. The arrangement of claim 7, wherein the door motor, the encoder measuring the travel of the door, and the door switches are connected directly to the elevator control system through buses.

10. The arrangement of claim 7, wherein the door motor, the encoder measuring the travel of the door, and the door switches are connected through buses to a door control card, which is connected to the elevator control system through a bus.

11. The arrangement of claim 1, wherein the automatic door comprises an elevator car door and an elevator landing door.

12. A method for monitoring the operational condition of an automatic door of an elevator, particularly a passenger and/or goods elevator, or of a building, said method comprising the steps of: determining the operational condition of the automatic door, which comprises one or more door leaves, a door mechanism and/or a closing device; determining state information of the door during an operating cycle; determining mechanical power of the shaft of the door motor during an operating cycle; determining from the mechanical power of the shaft of the door motor mechanical energy of the shaft during an operating cycle; determining, on the basis of the mechanical energy of the shaft of the door motor and the door state information, the magnitude of a friction force and/or the amount of potential energy stored in the door mechanism; and determining the operational condition of the door mechanism and/or the closing device on the basis of the magnitude of the friction force and/or the amount of the potential energy stored in the door mechanism.

13. The method of claim 12, further comprising the step of determining an elastic constant of the closing device or a mass of a weight from the amount of the potential energy stored in the door mechanism.

14. The method of claim 12, wherein the door state information during the operating cycle comprises information on when the door is closed, before opening, when the door is open, and when the door is closed, after opening.

15. The method of claim 12, wherein the mechanical power of the shaft of the door motor is determined by measuring the current and voltage of the door motor during the operating cycle, by calculating the electric power of the door motor and by subtracting from the electric power internal dissipation powers of the door motor, which comprise power losses induced by the coil resistance of the door motor.

16. The method of claim 12, wherein the mechanical power of the shaft of the door motor is determined on the basis of the angular velocity and torque of the door motor, or by measuring the current of the door motor and utilizing a current to torque function of the door motor for estimating the torque.

17. The method of claim 12, further comprising the step of monitoring the condition of the automatic door using an arrangement for monitoring the operational condition of an automatic door, the arrangement comprising: an automatic door comprising one or more door leaves that slide in their location horizontally; a door operator comprising a door motor and a door mechanism for moving the door leaf in its location horizontally; a closing device for closing the automatic door; a control system of the door operator for controlling the door motor; and a device configured to define the operational condition of the closing device and the door mechanism of the automatic door, wherein the device configured to define the operational condition of the closing device and the door mechanism of the automatic door comprises a mechanism configured to determine mechanical energy of the shaft of the door motor of the automatic door during an operating cycle.

18. The arrangement of claim 2, wherein said device configured to define the operational condition of the door mechanism and/or the closing device of the automatic door comprises a mechanism configured to determine the magnitude of the friction force and/or the amount of potential energy stored in the door mechanism, during an operating cycle.

19. The arrangement of claim 2, wherein said device configured to define the operational condition of the closing device and the door mechanism of the automatic door comprises a condition monitoring algorithm, which is implemented: in a control system of the door operator, or in an elevator control system, or in a separate measuring system, or in a local user interface, or in a remote user interface, or on a remote server.

20. The arrangement of claim 3, wherein said device configured to define the operational condition of the closing device and the door mechanism of the automatic door comprises a condition monitoring algorithm, which is implemented: in a control system of the door operator, or in an elevator control system, or in a separate measuring system, or in a local user interface, or in a remote user interface, or on a remote server.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) The invention will now be described in greater detail by means of preferred embodiments, with reference to the accompanying drawings, in which:

(2) FIG. 1 shows schematically a preferred embodiment of an arrangement for monitoring the condition of an automatic door in an elevator in accordance with the invention, which arrangement may utilize the method of the invention,

(3) FIG. 2 shows schematically a preferred embodiment of the arrangement for monitoring the condition of the automatic door in accordance with the invention, in which actuators and sensors of the door are connected directly to an elevator control system,

(4) FIG. 3 shows schematically a preferred embodiment of the arrangement for monitoring the condition of the automatic door in accordance with the invention, in which actuators and sensors of the door are connected to a door control card, which is connected to an elevator control system,

(5) FIG. 4 is a block diagram of a preferred embodiment of a method for monitoring the condition of an automatic door in accordance with the invention.

DETAILED DESCRIPTION OF THE INVENTION

(6) FIG. 1 is a schematic side view of an arrangement for monitoring the condition of an automatic door in an elevator in accordance with an embodiment, the arrangement comprising an elevator car 1, a counterweight 2 and a suspension rope system 3 whose ropes interconnect said elevator car 1 and counterweight 2. The elevator car 1 and the counterweight 2 are arranged for being moved by exerting vertical force on at least the elevator car 1 or the counterweight 2 by means of elements M, 6, 3. The suspension rope system 3 comprises one or more ropes. The elevator is preferably a passenger and/or goods elevator that is mounted to travel in a shaft S in a building. In the embodiment of FIG. 1, means for exerting the force on at least the elevator car 1 or the counterweight 2 comprise the suspension rope system 3, which is connected to the elevator car and/or the counterweight, and a hoisting mechanism M, which comprises means for moving the suspension rope system 3, which means preferably comprise a drive device, e.g. a motor, and a drive member 6 to be rotated, preferably a drive wheel. The hoisting mechanism M is placed in the vicinity of the upper end of the path of the elevator car 1. The hoisting mechanism M is thus in power transmission connection with the elevator car 1 and the counterweight 2 through the suspension rope system 3, the hoisting mechanism M being arranged, in particular, to exert upward pulling force on the elevator car 1 or the counterweight 2 through the suspension rope system 3. In the lower part of the elevator car 1 and the counterweight 2 there is attached a compensation rope 4 to balance an imbalance torque caused by the suspension ropes. In the elevator car 1, the car doors 7 and the landing doors 10 are on the same wall with the elevator car 1. A door operator 18 comprises a door motor 12 and a door mechanism for moving a door leaf in its location horizontally.

(7) The hoisting mechanism M may also be placed in the vicinity of the lower end of the path of the elevator car 1. The hoisting mechanism M is thus in power transmission connection with the elevator car 1 and the counterweight 2 through the hoisting rope system 4, the hoisting mechanism M being arranged, in particular, to exert downward pulling force on the elevator car 1 or the counterweight 2 through the hoisting rope system 4. In that case, in the normal drive of the elevator, a rope in the suspension rope system 3 need not transmit, through the outer surface of the rope, forces in the longitudinal direction of the rope, and no shearing forces in the direction of the surface are exerted on the load-bearing part of the rope or on an optional coating thereon. The ropes of the suspension rope system 3 may be suspended by deflecting about a rope pulley, which need not be a driven drive wheel. As presented, the elevator comprises a rope pulley 5 and/or rope pulleys in the vicinity of the upper and/or lower end of the path of the elevator car 1. Supporting on the rope pulley 5, for instance, a rope or ropes of the suspension rope system 3 carry the elevator car 1 and the counterweight 2. In the embodiments described this is implemented by 1:1 suspension, whereby the ropes of the suspension rope system 3 are connected by the first end to the elevator car 1 and by the second end to the counterweight 2. The suspension ratio may also be other than that, e.g. 2:1, but the ratio of 1:1 is advantageous, because in some embodiments a large number of rope deflections is not advantageous, due to the amount of space required by the deflections. Advantageously the rope pulleys are non-driven rope pulleys, and consequently the upper parts of the elevator may also be provided spacious. The rope pulleys are in an elevator shaft S, whereby no separate engine room is needed.

(8) FIG. 2 shows schematically an arrangement for monitoring the condition of an automatic door in accordance with an embodiment, in which the actuators and the sensors of the automatic door are connected directly to the control system of the elevator. The object is to provide a reliable and advantageous method for monitoring the condition of automatic doors in an elevator or a building. The arrangement of FIG. 2 for monitoring the condition of an automatic door in an elevator comprises an elevator door motor 12, an encoder 14, or the like, measuring a door travel, door switches 13, which comprise door open or door closed switches, electric wiring 15 for the elevator or building door 7 and the motor 12. Preferably the door motor 12 is a DC motor or an AC motor, preferably a single-phase or a multi-phase electric motor. Signals provided by the encoder 14 measuring the door travel pass along a bus 16. The travel may also be measured in some other way than with the encoder. The signals of the switches 13 pass along a bus 17. The door control system 9 of the elevator or the building controls the door motor 12 and reads the signals 16 and 17.

(9) FIG. 3 shows schematically the arrangement for monitoring the condition of the automatic door in accordance with an embodiment, in which actuators and sensors of the door are connected to a door control card 8, which is connected to an elevator control system 9. The arrangement of FIG. 3 for monitoring the condition of an automatic door in an elevator comprises an elevator door motor 12, an encoder 14, or the like, measuring a door travel, door switches 13, which comprise door open or door closed switches, electric wiring 15 for the elevator or building door 7 and the motor 12. Preferably the door motor 12 is a DC motor or an AC motor. Signals provided by the encoder 14 measuring the door travel pass along a bus 16. The travel may also be measured in some other way than with the encoder. The signals of the switches 13 pass along a bus 17. The door motor 12, the encoder 14 measuring the door travel, and the door switches 13 are connected to a door control card 8, which is connected to an elevator control system 9 along a bus 11. The door control system 9 of the elevator or the building controls the door control card 8, which controls the door motor 12 and reads the signals 16 and 17. By means of the current of the door motor 12 as a function of time I.sub.M(t) and the voltage of the door motor 12 as a function of time U.sub.M(t) it is possible to calculate the electric power used by the door motor 12. The electric power is consumed by copper and iron losses of the door motor 12 and mechanical work needed for moving the door 7.

(10) FIG. 4 is a block diagram of an arrangement for monitoring the condition of an automatic door in accordance with an embodiment. By means of the current of the door motor 12 as a function I.sub.M(t) of time t and the voltage of the door motor 12 as a function U.sub.M(t) of time t it is possible to calculate the electric power P(t) used by the electric motor 12 as a function of time t. The electric power is consumed by copper and iron losses of the door motor 12 and mechanical work needed for moving the door 7. In accordance with the invention, the method measures the current I.sub.M(t) and voltage U.sub.M(t) of the door motor 12 and calculates a cumulative quantity, i.e. energy supplied to the door motor 12. During the door operation the mechanical energy applied to the system by the shaft of the door motor 12 is converted to kinetic energy of the door masses, to potential energy of the door closing device and is consumed by internal frictions in the door motor 12 and frictions in the door mechanism. In addition, door state information s is also needed. Particularly important points in the door operation are the door 7 completely closed, after a door cycle, and the door 7 completely open, when the door motor 12 keeps the door 7 open by torque.

(11) Mechanical energy E.sub.MS used for a door open/closed cycle is an indication of the basic adjustments and operational condition of the door. When this energy is distributed onto a travelled distance d, the energy consumed can be normalized per meter travelled. This is called a friction force resisting motion F, the unit thereof being Newton N. The friction force resisting the motion of the door mechanism can be calculated by equation:
F=E.sub.MS(closed)(2d.sub.nom).sup.1(1)
where E.sub.MS is the mechanical energy of the motor shaft, which is consumed when the door was closed, it was opened, and after opening it was closed again, and d=d.sub.nom is the travel of the door.

(12) When the door 7 is open, the shaft energy of the door motor 12 has not only be consumed in frictions but also stored as potential energy in the door closing device, preferably a spring, in other words,
E.sub.MS(open)=Fd.sub.nom+k.sub.Sd.sub.nom.sup.2(2)

(13) In formula (2), k.sub.S is a springback factor of the closing spring. In general, the opening and closing speeds of the door 7 are different. For reasons of impact energy and comfort the opening of the door 7 may usually take place faster than the closing. Formulae (1) and (2), used in this manner, involve an assumption that most of the friction is velocity-independent Coulomb friction and the share of velocity-dependent bearing frictions may be incorporated in this friction without any significant error.

(14) The force factor of the spring can be obtained by formula (2)
k.sub.S=(E.sub.MS(open)Fd.sub.nom)2d.sub.nom.sup.2(3)

(15) In formula (3) it is to be noted that k.sub.S is the effective elastic constant of the closing device with the assumption that the travel of the spring is the same as the nominal travel of the door. Preferably, in the doors, the spring is connected to a door leaf having the shortest travel. The number of leaves is preferably two or three. In that case, the respective transmission ratios are R=1/2 or R=1/3, and consequently d.sub.nom=R d.sub.nom must be substituted in formulae (1) and (2).

(16) For condition monitoring it is sufficient to observe the value of the effective elastic constant, but if it is desired to compare a found value with a reference value, for instance, the transmission ratio has to be taken into account.

(17) In case the closing device is based on a mass and the earth's gravity, a parameter representing the condition of the closing device, the mass of the closing weight m.sub.CD may be deduced in a corresponding manner
m.sub.CD=(E.sub.MS(open)F.Math.d.sub.nom)(gd.sub.nom).sup.1(4)
where g is the earth's gravitational acceleration 9.81 m/s.sup.2.

(18) The motor converts the input electric power P.sub.ME to mechanical shaft power P.sub.MS. The conversion is not ideal, but electrical and mechanical losses occur therein
P.sub.MS=P.sub.MEP.sub.MMLP.sub.cuP.sub.fe(5)
where P.sub.ME is the electric power supplied into the motor, P.sub.MS is the mechanical shaft power of the motor, P.sub.MML is the internal mechanical friction losses of the motor and gear system optionally integrated therewith, P.sub.cu is the losses produced in the motor circuitry, i.e. so-called copper losses, and P.sub.fe is the losses produced in the magnetic circuits of the motor, i.e. so-called iron losses.

(19) The internal friction losses of the door motor 12, as well as the iron losses, are difficult to approach in a sufficiently simple manner in an application like this. On the other hand, it may be assumed that the internal frictions in the door motor 12 are small in comparison with the frictions in the whole door mechanism. The same applies to iron losses, and formula (5) may be simply written as
P.sub.MS=P.sub.MEP.sub.cu(6)
and the corresponding shaft energy over the time period observed
E.sub.MS=(P.sub.ME(t)P.sub.cu(t)dt=(P.sub.ME(t)I.sub.M(t).sup.2R.sub.S(T))dt(7)

(20) In formula (7) I.sub.M is the motor current and R.sub.S(T) is the resistance of the motor circuit at actual temperature T of the motor. The resistance of the copper winding and current losses therewith vary along with the temperature, so the resistance of the winding is to be measured separately for each door operation. Another matter that supports online measurement of the resistance is that it enables omission of one parameter to be set in advance.

(21) The resistance measurement is based on the fact that, when the motor shaft is locked into place, all the electric energy supplied to the motor converts to heat in the circuit of the motor. This situation occurs advantageously at least once during the door operating cycle, the door motor 12 keeping the door open by torque. In that case it must be that
U.sub.M(t)I.sub.M(t)dt=I.sub.M(t).sup.2R.sub.S(T))dt(8)
wherefrom it is easy to work out the searched R.sub.S(T) from the measurement data. In formula (8) U.sub.M is the voltage acting over the motor circuit.

(22) In practice, the simplicity of formula (6) implies that the internal frictions in the door motor 12 and the iron losses of the door motor 12 are transferred as equivalent additional frictions to the door mechanism, and they cannot be distinguished therefrom. In a condition monitoring application that is not of importance, however, and at worst, an error in the order of 10% is concerned.

(23) Preferably, in the door 7, the spring of the closing device is connected to a slower moving door and the elastic constant k.sub.S is calculated considering the transmission R.

(24) The method is capable of reliably detecting both the operational frictions of the door and the operational condition of the closing device of the landing door.

(25) If detected that the friction forces have increased and/or the condition deteriorated beyond a predetermined limit value, it is stated that the automatic door needs repair and work for maintenance or replacement of automatic door components is started.

(26) Preferably the elevator is an elevator suitable for transporting passengers and/or goods, which is mounted in a building to move vertically, or at least substantially vertically, preferably on the basis of landing and/or car calls. The elevator comprises one or more elevator units and the elevator car preferably comprises an interior space that is most preferably suitable for receiving a passenger or several passengers. The elevator comprises preferably at least two, preferably more, landings to be served.

(27) Inventive embodiments are also disclosed in the specification and drawings of this application. The inventive contents of the application may also be defined in ways other than those described in the following claims. The inventive contents may also consist of several separate inventions, particularly if the invention is examined in the light of expressed or implicit sub-tasks or in view of obtained benefits or benefit groups. In such a case, some of the definitions contained in the following claims may be unnecessary in view of the separate inventive ideas. Features of the different embodiments of the invention may be applied to other applications within the scope of the basic inventive idea.

(28) Inventive embodiments are also disclosed in the specification and drawings of this application. The inventive contents of the application may also be defined in ways other than those described in the following claims. The inventive contents may also consist of several separate inventions, particularly if the invention is examined in the light of expressed or implicit sub-tasks or in view of obtained benefits or benefit groups. In such a case, some of the definitions contained in the following claims may be unnecessary in view of the separate inventive ideas. Features of the different embodiments of the invention may be applied to other embodiments within the scope of the basic inventive idea.

(29) It is obvious to a person skilled in the art that as technology advances, the basic idea of the invention may be implemented in many different ways. The invention and its embodiments are thus not restricted to the above examples but may vary within the scope of the claims.