CONTROL SYSTEM FOR A DOOR

Abstract

 A method is described in which a slack cable is detected in a door operating system. The operating system is provided with a motion sensor which detects whether or not the door is moving, a switch member connected to an electrical power source, a motor connected to the switch member which controls the door by means of the cable, and a switch connected to the decision unit which interrupts the electrical power supply to the motor, if a confirmation from the movement sensor that the door is moving has not been received within a certain period of time after operating the switch member.

Description

[0001] The present invention relates to a method in which a slack cable is detected in a door operating system.

[0002] The present invention also relates to a door operating system.

[0003] Such a method and operating system are known from WO 99/08956. A slack cable detection and compensation system is disclosed herein which generates a warning signal if parts of the system for compensating play in the cable by means of a spring force have been withdrawn to a certain extent. With the aid of a position sensor, the mutual position of those components is monitored and in the event of an excess of play, a switch coupled to the position sensor switches over to signal an alarm.

[0004] A drawback of the known method and operating system is that it is not easy to build it into existing doors which moreover are not always provided with a slack cable compensation system.

[0005] An object of the present invention is to provide a simple method with an associated operating system that can be mounted on all kinds of existing doors as a slack cable detection system.

[0006] To this end, the method according to the invention has the features that the operating system is provided with:

• a motion sensor which detects in a contactless manner whether or not the door is moving;
• a switch member connected to an electrical power source;
• a motor connected to the switch member which operates the door by means of the cable; and
• a decision unit connected to the switch member, which interrupts the electrical power supply to the motor, if a movement sensor confirming that the door is moving has not been received within a certain period of time after operating the switch member.

[0007] Accordingly, the operating system according to the invention has the features of claim 5.

[0008] An advantage of the present invention is that it allows contactless detection of a possible slack cable. In particular, no physical connection to the so-called door leaf of the door, for example by means of a spiral cable, is required. The dangers associated with a slack cable, in particular where it concerns a fall of the door as a result of play in the cable (s), at that time possibly followed by a cable break, have been eliminated. This improves the safety of the user when applying the method according to the invention, and prevents damage and failure of the door which is operated by means of the operating system according to the invention. And this in a way that makes installation and simple combining with existing doors possible regardless of their dimensions or thicknesses.

[0009] In one embodiment, the time span after operating the switch member within which a confirmation from the movement sensor that the door is moving must have been received is adjustable. The advantage of this is that, to some extent, depending on the inertia of the door in particular, this time can be adjusted in such a way that the extent to which the door would move a little under certain circumstances, if the cable is slightly slack, can be reduced to harmless proportions. Only when the adjustable time is exceeded the slack cable protector intervenes and the motor will no longer be energized, after which a possible automatic locking of the door can come into effect.

[0010] A preferred time span for a conventional door such as an overhead door is approximately 0.5 seconds at most.

[0011] Further detailed possible embodiments set out in the other claims are listed in the following description together with the associated advantages.

[0012] The method and operating system according to the present invention will now be further elucidated with reference to the figure below. This shows the principle diagram of the door operating system according to the invention, in which the corresponding method is applied.

[0013] The figure shows the principle diagram of a control system 1 for operating a door 3, such as an overhead door, by means of a number of cables 2, often under spring force. The operating system 1 comprises a movement sensor 4 which is adapted to detect in a contactless manner a movement of the door 3, a switch member 6 connected to an electrical power supply 5; an electric motor 7 connected to the switch member 6 and adapted to operate the door 3 by means of the cable 2; and a decision unit 8 connected to the switch member 6 and adapted to interrupt the electrical power supply to the motor 7 if a signal from the movement sensor 4 has not been received by a user of the door within a certain period of time after switching on the switch member 6 confirming that the door 3 moves.

[0014] If, after giving the switch 6 command that the motor 7 has to move the door, the door is actually in motion and that movement is detected by the movement sensor 4 and is supplied to the decision unit 8, the switch 6 does not interrupt power to the motor 7. However, if after that command the door does not appear to start moving within a certain period of time, the unit 8 decides that the switching member 6 must no longer switch the power supply to the motor 7, causing the motor to stop. There is then a suspicion of a slack cable failure or possibly a cable or spring break as a result of which the door did not start moving, or at least not in time. Stopping the motor 7 in time prevents the motor from pulling on the cable(s) 2 for such a long time that this could cause undesired damage or, for example, the door warping. In that state, a signal can then be generated that there is a defect that must be examined by a person skilled in the art. In general, a block will therefore be activated which at least prevents the door from moving down or falling down on its own.

[0015] The usually adjustable period of time will be monitored in the decision-making unit 8 in a manner known per se by a time counter which furthermore keeps track of the passage of time within the set period of time. The motor 7 remains energized during the time period. However, if the confirmation by sensor 4 has not been given to the unit 8 within that time frame that the door is moving, then the power supply to the motor 7 is interrupted by the controllable switch 6 at the command of the decision unit 8.

[0016] In practice, the time span will run for a maximum of about 0.5 seconds, which is generally sufficient to accommodate any cable play occurring during that time, given the weight of the door.

[0017] The motion sensor 4 is a contact-free sensor and can be an optical and / or a magnetic sensor. In the case of an optical sensor, it comprises a combination of a light transmitter directed at the door and a cooperating receiver which is adapted to receive light emitted by the light transmitter after reflection on the door. From the reflected light, the signal can be derived in a known manner whether the door 3 moves or not. This signal is then applied to the decision unit 8 and used, as explained above.

[0018] If the sensor 4 is of the magnetic type, it may comprise a combination of a well-known reed switch which cooperates with a magnet to be mounted on the door 3. Only if and as long as the magnet is within range of the reed switch does the latter take a first position; if not, the reed switch switches to a second position. This relevant switching information is then communicated to the decision unit 8 and used, as explained above.

[0019] The aforementioned information can also be used to communicate via a wireless or non-wireless communication system, such as a mobile telephone, to an instance or person who can rectify the determined cable malfunction.

Claims

1. A method in which a slack cable is detected in a door operating system,
which operating system is further provided with:

- a motion sensor which detects in a contactless manner whether or not the door is moving;

- a switch member connected to an electrical power source;

- a motor connected to the switch member which operates the door by means of the cable; and

- a decision unit connected to the switch member, which interrupts the electrical power supply to the motor, if a movement sensor confirming that the door is moving has not been received within a certain period of time after operating the switch member.

2. Method according to claim 1, characterized in that said time span is an adjustable time span.

3. Method according to claim 2, characterized in that the adjustable time span is less than 0.5 seconds.

4. Method according to one of claims 1 to 3, characterized in that the motion sensor is an optical and / or a magnetic sensor.

5. Control system for a cable-operated door that is provided with:

- a motion sensor adapted to detect a movement of the door in a contact-free manner;

- a switch member connectable to an electrical power supply;

- a motor connected to the switching member and adapted to operate the door by means of the cable; and

- a decision unit connected to the switch member and adapted to interrupt the electrical power supply to the motor, if a signal from the movement sensor has not been received within a certain period of time after operating the switch member confirming that the door is moving.

6. Operating system according to claim 5, characterized in that the motion sensor comprises an optical and / or a magnetic sensor.

7. Operating system according to claim 6, characterized in that the optical sensor comprises a combination of a light transmitter directed to the door and a light receiver which is adapted to receive light emitted by the light transmitter after reflection on the door so as to derive the signal therefrom.

8. Operating system according to claims 6 or 7, characterized in that the magnetic sensor comprises a combination of a reed switch and a magnet to be mounted on the door.

9. Method or operating system according to one of the concerning preceding claims, characterized in that information on a weak cable at the relevant door is communicated to an instance on the basis of the signal via a wireless or non-wireless communication system.

10. Method or operating system according to claim 9, characterized in that the door is an overhead door.

Drawing