Abstract:
A method for monitoring motion of a drive-operable door body between open d closed positions. To monitor movement as sensitively as possible, an actually occurring course of movement is compared with a previously fixed nominal course. A signal for interrupting movement is generated when the nominal course and the actual course, and/or one of the derivations of these, differ from one another by a previously fixed amount.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a method for the monitoring of the motion of a drive-operable, one or multiple part door body, particularly an overhead door, along the movement path between the open and closed position and for the interruption of this motion, particularly by switching off and over the drive in the event of an obstacle in the path of movement which the door body runs against with the following steps: 
     an actual course which really occurs and dependence on the movement path or the time of a physical operating value of the movement of the door body is recorded, and 
     an interruption signal for the interruption of the motion of the door body being monitored is generated if the currently recorded value of the actual course differs by a previously determined amount from the corresponding value of a nominal course with the nominal course on the basis of a physical operating value being recorded and stored at least once before the putting into operation of the door for an obstacle-free normal operation along the movement path or the time, and to a means to perform the method in accordance with a door drive, a measuring element to measure the movement path, a measuring element to measure a physical operating value of the door motion, a memory to store the nominal course and/or actual course determined by the measuring elements in dependence on the movement path or the time and a control unit to evaluate the nominal course and the actual course and to generate an interruption signal. 
     Such a method and such a means are known from EP-B1-0 083 947. The monitoring unit disclosed therein is based on the basic idea that the actual course of the required force to drive the door body over the movement path is compared continuously with the nominal course. If the difference between actual course and nominal course exceeds a previously fixed amount, an interruption signal is generated which switches off the door body drive or reverses its direction of movement. The nominal course is here recorded and stored at least once prior to the putting into operation of the door for an obstacle-free normal operation along the movement path. 
     Such a monitoring system possesses an improved hazard protection over other known monitoring systems such as electrical contacts positioned underneath yielding bulges. Nevertheless cases can still occur with such a monitoring means where the criterion to generate the interruption signal is not sufficiently sensitive. If the door body edge contacts soft obstacles, for example, the motion force for the movement of the door body increases more slowly than against a hard obstacle so that a longer period passes before the interruption signal is triggered. If, therefore, the edge of the door body laterally contacts, for example, the groin of person accidentally crossing the motion path during the movement of the door body, then is it possible that the interruption signal of the monitoring device will not be triggered early enough. 
     SUMMARY OF THE INVENTION 
     It is therefore the object of the present invention to monitor as sensitively as possible the motion of movement between the open position and the closed position of doors of the type in question for any deviation from normal operation. 
     Based on a method of the generic type this object is solved in accordance with the present invention by the steps of an actually occurring actual change of course dependent on the movement path or the time is determined by forming the derivation according to the movement path or the time for every recorded value of the actual course, and 
     an interruption signal for the interruption of the motion of the monitored door body is generated if the currently determined value of the actual change of course differs to a previously determined extent from the corresponding value of a nominal change of course with the nominal change of course being determined and stored at least once before the putting into operation of the door based on the nominal course. The solution in accordance with the invention consists of the fact that in addition to the known methods a derivation of the actual course of a physical operating value of the door movement is formed at each scanned point in accordance with the movement path and that an interruption signal is generated even if a criterion is not met in accordance with the derivation determined. The nominal course of the corresponding physical operating value is here recorded and stored at least once before the putting into operation of the door for an obstacle-free normal operation along the movement path. 
     The advantages achieved with the present invention comprise particularly the monitoring unit reacting equally sensitively when the door contracts hard objects and/or soft objects. This improvement can be achieved here with relatively low effort over a monitoring unit of the generic type. 
     Preferably, for the formation of the actual change of course and/or the nominal change of course the first derivation is formed according to the movement path or the time; however, higher derivations can also be used. 
     The difference value to be given, by which the actual change of course has to differ from the nominal change of course in order to signal the event of an obstacle, is, on the one hand, dependent on external influences such as wind influences, slight icing and similar and, on the other hand, it takes slight changes in the run resistance into account. In accordance with a preferred embodiment a fixed difference value is fixed beforehand over the total motion run, but in principle the difference value can, however, also be measured differently over the movement path, particularly to compensate for the different wind impairment depending on the motion path already laid back. 
     In principle, the nominal course and the actual course can be derived from different physical operating values of the forward movement, but preferably the same physical starting values will be evaluated for both values. 
     In accordance with a preferred embodiment the nominal course is only recorded and stored after the installation of the door on site and then the nominal change of course should be determined and also stored. In this way, the actually occurring operating relationships can be taken into account under normal conditions in a realistic manner with the actually prevailing environmental influences. As the operating relationships can change over time due to wear or similar, the nominal course can be recorded and stored again after certain operating intervals of the door and a new nominal change of course determined from this. It is naturally, however, also possible to give and store the nominal course at the time of manufacture depending on the type of door. The nominal change of course can also be determined and stored once, but it is also possible to have the nominal change of course determined again during operation for every movement of the door body on the basis of the nominal course. 
     The determination in dependence on the path of a physical operating value of the door body motion can be done in various ways. Preferably, the driving force of the door body is used as the basis with this being able to be determined in turn by a direct measurement of force or also by a measurement of torque. A preferred method of measuring the torque consists of determining the torsion angle between two coupling elements connected elastically to one another and positioned behind one another as part of the path of the driving force. However, it is also possible to monitor in a known fashion the performance of an electrical drive motor or the current supplied with a constantly applied voltage. 
     If the above measuring values of a physical operating value of the motion of a door body are recorded in dependence on the movement path, then it is necessary for this purpose that the movement path itself also be determined by a suitable measuring device. For this purpose, preferably a pulse generator is used which is also driven by the driving motor. In connection with two switch elements which detect the opening position and the closing position of the door body, the current position on the movement path can be determined with the pulse generator within the resolution precision of the pulses emitted. 
     In accordance with another preferred embodiment it is provided that the rate of motion of the door body is taken as a measure of a physical operating value of the motion. Here, the rate of motion is no longer recorded in dependence on the movement path but in dependence on the time. A course of speed for normal operation without any obstacles also recorded in dependence on the time serves as the nominal course. To measure the rate of motion a tachometer generator or also a pulse generator can be used which can be driven by the door drive. While the pulses emitted by the pulse generator have still to be derived into a frequency proportional to the speed, the tachometer generator already supplies a voltage proportional to the rate of motion of the door. 
     Another solution of the above task in accordance with the invention consists of a device to perform the method in accordance with the invention with the control unit possessing a derivative element which generates a nominal change of course from the nominal course and/or an actual change of course from the nominal course each in dependence on the movement path or the time, the nominal change of course and/or the actual change of course can be stored in the memory and the nominal change of course and the actual change of course can be evaluated by the control unit. 
     In accordance with its basic design, the device comprises a door drive, a measuring element to measure the movement path, a measuring element to measure a physical operating value of the door movement, a control unit with memories for the measuring values and a derivative element. 
     In accordance with a preferred embodiment the control unit comprises a microcontroller in which corresponding memories and A/D converters have already been integrated. Preferably, the derivative element is also implemented on the microcontroller in the form of a software logic. However, it is also feasible that the derivative element comprises an analog derivator whose signal is also supplied to an A/D converter. In any case, the derivative element must be designed in such a way that the current derivation of the input signal in question is determined reliably independent of momentary noise interference. 
     In accordance with another preferred embodiment the door drive comprises an electrical motor. The power of the electrical motor supplied can here be taken directly as the measure for a physical operating value of the door motion. With a constantly supplied voltage, the current supplied to the electrical motor can also serve as the basis for a physical operating value with the current being measured then approaching a measure for the moment given by the electrical motor. 
     In accordance with another preferred embodiment it is provided that the interruption signal generated by the control unit results in a switching off of the electrical motor. However, it is also possible that the direction of drive of the door drive will reverse as a result of the interruption signal which can be done with a suitable electrical motor by reversing the polarity of the supply voltage or also by a suitable gear. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Further details and advantages of the invention are described in more detail by means of an embodiment shown in the drawing where: 
     FIG. 1 is a schematic representation of a garage door movable overhead with a block diagram of the monitoring system in accordance with the invention, and 
     FIG. 2a is a front view of a schematic representation of a pulse generator on an elastic coupling. 
     FIG. 2b is a side view of the schematic representation of a pulse generator on an elastic coupling. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The garage door from FIG. 1 possesses two vertical braces 1 to whose top end two rails 2 connect in which the door body 3 is guided. The door body 3 is further hinged to the braces 1 with a connecting rod not shown so that the door body can be opened and closed with an overhead movement. In addition, equalizing springs are provided which largely compensate the door body&#39;s own weight during the movement and which hold the door body in its defined end positions. The drive system designated with number 4 consists in total of a drag-chain drive with a drag chain 5, to which the door body 3 is hinged and which is guided over the turn pulley 6 and over a drive pulley (not shown). The drive pulley is located in the drive unit 7 and is driven by the electrical motor 9 via a gear. Also driven by the electrical motor 9 is an impulse generator 8 which is mounted on an elastic coupling and which emits a pulse after every certain angle of rotation. 
     The whole system is controlled by the control unit 10 which consists of a microcontroller with an integrated memory and A/D converters. The output signal of the control unit 10 is supplied to an amplifier 11 which supplies the required power to the electrical motor 9 via a current measuring element 12. The input values of the control unit include the measuring values 8a and 12a, the switch signals 13a and 14a and input signals 15 (not specified in any detail) which can include signals of an operating unit or also a voltage supply. 
     The signal 8a of the pulse generator is evaluated by the control unit in connection with signals from switch elements 13 and 14. Here the switch elements are actuated by the door body 3 in its end positions, that is in the vertical and in the horizontal position in each case. Signals 13a and 14a therefore each serve as start/stop signals in order to ensure a reliable upward integration of the signal 8a. 
     FIGS. 2a and 2b show a possible embodiment of the pulse generator 8. In an axial cross-section and in a radial section a coupling is shown which is provided between the driving wheel of the drag chain 5 and the outlet of the drive motor 9. The driven coupling half 20 is designed as a rotating, elastic coupling element with a radial intermediate layer between teeth and hub, for example in the form of a rubber ring 21. The output coupling half 22 possesses on its radial circumference teeth 23 which are sensed by the inductive generator 24. When the coupling turns, the inductive generator 24 then emits corresponding pulses due to the periodic change in the inductance. 
     With such an elastic coupling it is also possible to determine the torque given by the electrical motor 9 by measuring the angle of torsion between the driven coupling half 20 and the output coupling half 22. In the present embodiment this is, however, done by the current measuring element 12 which measures the current supplied to the electrical motor. The evaluation of the measuring signals 8a and 12a is described here in the following: 
     Before the door drive is put into operation the nominal course of the motor current for obstacle-free normal operation is recorded in dependence on the movement path. For this purpose, the signals 8a and 12a are read into the microcontroller via A/D converters at identical scan times and stored in such a way that an allocation of values of identical times is possible. Together with the control program of the drive control the nominal course thus recorded is stored in the EPROM so that the values can be reloaded into the RAM at every reset of the microcontroller. 
     During an opening or closing movement of the door body an actual course of the motor current according to the nominal course is recorded in dependence on the movement path. For each actual value recorded a calculation process is performed before the recording of the next actual value, that is within one scan period, which calculation process checks whether any unpermitted differences from the nominal course exist and whether accordingly an interruption signal has to be generated. 
     For this purpose, first each actual value recorded is compared to the corresponding nominal value for identical values of the movement path. If the actual value differs from the nominal value by a previously determined amount, then an interruption signal is generated by the microcontroller which signal results in a reversal of the drive direction of the door body. 
     If, in contrast, the actual course is within a permitted range, then in a next step for the currently recorded actual value the derivation is formed in dependence on the movement path. For this purpose, different methods are feasible, the simplest consists of the forming of a difference between the currently recorded actual value and the previously recorded actual value. If the actual values are particularly loaded with noise, then a smoothing of the previous values may be necessary prior to forming the difference. To do this, a certain number of previously recorded actual values are interpolated with a given function before the derivation is then formed from this interpolated function. The currently determined derivation is included in an actual change of course which is compared with a nominal change of course. This nominal change of course was also determined and stored in accordance with the method just described prior to the putting into operation based on the already recorded nominal course. If the actual change value differs from the nominal change value by a previously determined amount, then an interruption signal is generated which in the results in a reversal of the drive direction of the door body. 
     In accordance with the method described above, the already known criterion between nominal course and actual course is therefore supplemented by an additional criterion between nominal change of course and actual change of course which allows a more exact evaluation for the generation of an interruption signal. Of course, in addition to the derivation criterion other further criteria are feasible, in particular the nominal course can be compared more and more exactly with the actual course by forming further derivations. The limit here is formed by the already mentioned noise behavior of the two signals with a minimum tolerance width being required between the actual course and the nominal course so that the interruption signal is not triggered when not desired. 
     In addition to the method described for the recording of the nominal and actual courses in dependence on the movement path, it is besides also possible to record the actual and nominal courses in dependence on the time. The requirement for this is that the course of movement of the door body does not change over time. For this purpose it must be ensured that friction influences and any other interference influences can be neglected. This can be taken into account in a limited fashion by the nominal course being recorded again after regular maintenance intervals. If the interference influences can accordingly be neglected, then it is also possible to dispense with the current sensor 12 by having the rate of speed of the door body being determined over time from the signal of the pulse generator 8.