Abstract:
The invention relates to an elevator unit comprising an elevator car which is movable in an elevator shaft and is equipped with a braking device and a catching device encompassing catching elements. The elevator unit further comprises a system for detecting signals used for determining an absolute position of the elevator car, a control circuit for detecting signals used for determining the speed or deceleration of the elevator car, and a circuit for evaluating the signals of the detection system and the control circuit. Based on the input signals, the evaluation circuit evaluates whether the speed of the elevator car lies within a predefined interval in the determined position and causes the braking device to be actuated via a first output of the evaluation circuit and/or the catching device to be triggered via a second output of the evaluation circuit according to the result of the evaluation.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims the benefit of priority to PCT/EP2005/014043, filed 27 Dec. 2005, which claimed priority to European patent application serial number 05000289.8, filed 7 Jan. 2005; each of these applications is incorporated herein by reference. 
     
    
     FIELD 
       [0002]    The present invention relates to an elevator unit and a control device for an elevator unit. 
       BACKGROUND 
       [0003]    Elevator units comprise an elevator car which is movable in an elevator shaft. It is common to install buffers as safety devices in a pit of the elevator shaft, in order to decelerate the elevator car as it travels past the lowest stop (or the counterweight as it travels past the topmost stop) in the event of malfunction of the drive. In elevators with high nominal speeds, very large buffers are required for this purpose. Large buffers require a deep pit, which is expensive to construct. Use of buffers satisfies safety regulations which prescribe that the elevator unit must be designed and constructed so as to prevent the car from crashing in the elevator pit (see, e.g., European Safety Standard EN81). 
         [0004]    In order to be able to make the buffers and hence the pit smaller, deceleration control circuits have already been proposed which allow the use of smaller single-use buffer devices as described for example in DE 20104389 U1 and DE 1021063 A1. 
         [0005]    An excess speed detector with a plurality of light barriers arranged on the elevator car is already known from EP 0712804 B1. The light barriers generate measurements using a measuring strip attached to one side of the elevator shaft, and the speed or deceleration of the elevator car can be determined using these measurements. The measuring strip is of a redundant construction and consists of a marking track and a control track. 
         [0006]    Moreover, in addition to the braking device provided for the elevator car, it is conventional and known to provide a catching device for emergencies, and this catching device comprises, in particular, catching wedges (cf. DE 29912544 U1). 
       SUMMARY 
       [0007]    A goal of the invention is to provide an elevator unit in which the buffer device and hence the pit of the shaft can be made smaller or eliminated. Accordingly, an elevator unit, a control device, and a method for controlling an elevator unit are disclosed. 
         [0008]    The elevator unit according to the invention and/or the control device according to the invention may operate as a reliable two-stage electronic system, thereby opening up the possibility of doing away with a safety buffer altogether or in part (by “in part”, it is meant that a smaller buffer could be provided, e.g. a cheap single-use buffer made of polyurethane, which is provided only for conceivable extreme cases). Thus, using the system according to the invention, existing buffer systems may consequently be made still smaller. 
         [0009]    The invention essentially comprises three components, namely a detection system for determining the absolute position of the elevator car, a deceleration control circuit for detecting signals used for determining the speed or deceleration of the elevator car, and, as a third component, an evaluating circuit for processing the signals supplied by the detection system and the deceleration control circuit. This is a so called redundant/diverse system. The redundant/diverse evaluation according to the invention is achieved by means of a two-channel evaluating circuit, wherein a first and a second sensor for detecting relevant signals are each connected in redundant/diverse manner to one of the two channels of the evaluating circuit and a third sensor for an (additional) two-out-of-three selection is connected to both channels of the evaluating circuit. 
         [0010]    One advantage achieved with the present invention is that a buffer of the kind described above may be omitted entirely, as the procedure according to the invention ensures reliable and unambiguous detection of the position of the elevator car in addition to determining its speed. Total replacement of a buffer may result in a very great space saving; for example, large (high-rise) elevator units commonly have corresponding car speeds of 6 to 7 meters/second and a buffer height of up to 8 or 9 meters. 
         [0011]    The safety evaluation features of the invention can therefore always advantageously be used whenever the elevator car has to be maintained at a certain spacing from an object located below or above it. In most cases, this object will be the pit of the shaft or the ceiling of the shaft, but it may also be a second elevator car travelling in the same elevator shaft underneath the elevator car (e.g., a TWIN® system of the present Applicant). 
         [0012]    Further features and embodiments of the invention will become apparent from the description and the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    It will be understood that the features described above and those to be explained hereinafter can be used not only in the particular combinations specified but also in other combinations or on their own without departing from the scope of the present invention. 
           [0014]    The invention is schematically shown by means of an embodiment shown in the drawings and is described in detail hereinafter with reference to the drawings. 
           [0015]      FIG. 1   a  shows a plan view of an arrangement for detecting signals for determining the absolute position of an elevator car. 
           [0016]      FIG. 1   b  shows the arrangement of  FIG. 1   b  in perspective view. 
           [0017]      FIG. 2   a  shows a plan view of an arrangement for detecting signals for determining the speed or deceleration of an elevator car for a deceleration control circuit. 
           [0018]      FIG. 2   b  shows the arrangement of  FIG. 2   b  in perspective view. 
           [0019]      FIG. 3  shows a structural diagram of an evaluating circuit. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0020]    As already mentioned herein, the system according to the invention essentially comprises three components. 
         [0021]    The first of these components is a detection system for detecting signals for determining an absolute position of the elevator car. A detection system of this kind may operate for example on the basis of a magnetic strip having a plurality of pole divisions arranged in a non-repeating pattern. Magnetic strips of this kind are known per se and are described for example in DE 19732713 A1 and DE 10234744 A1. German Patent Application 102004037486.4, which is incorporated herein by reference, also describes a double signal band for determining the state of motion of a moving body. 
         [0022]    A magnetic strip  90  of this kind which is suitable for performing the invention is shown in  FIGS. 1   a  and  1   b . The magnetic strip  90  comprises a plurality of pole divisions  92 ,  94  which are arranged in a non-repeating and hence unambiguous pattern. A magnetic sensor  9 , such as a Hall sensor, is arranged on the elevator car  6  (not shown in detail), and without making contact, it “reads” the pattern of the magnetic strip  90 , which is fixedly mounted in the elevator shaft (e.g., magnetic strip  90  is mounted in a recess in the elevator rails (not shown)). In addition to the absolute position, the speed of the elevator car  6  can also be derived from the signal supplied by the magnetic sensor  9 . Naturally, there are other methods familiar to those skilled in the art for determining the absolute position of an elevator car, which can be used within the scope of this invention (e.g., a laser measuring system operating on the principle of a bar code reader). 
         [0023]    The second of the components mentioned above is a control circuit.  FIGS. 2   a  and  2   b  show an arrangement which serves to detect signals in order to determine the speed or deceleration of an elevator car for the control circuit. This arrangement comprises a strip  70  on which a pattern  72 ,  74  is provided, wherein the pattern is capable of being detected by a sensor  7 . The strip is fixedly mounted in the elevator shaft in the region of the deceleration section of the elevator car  6  (e.g., above the pit or below the ceiling of the shaft, as the invention can equally be used above the pit or in the safety region at the top end of the shaft). The pattern of the alternating sensor-relevant measuring sections  72 ,  74  on the strip  70  is selected so that the detected signals produce a constant time value, i.e. the individual measuring sections  72 ,  74  become steadily shorter towards the upper end of the elevator shaft. Any inordinate deceleration of the elevator car can thus easily be detected by an evaluation as a result of deviation from the constant desired time value. 
         [0024]    The strip  70  for detecting signals in order to determine the speed or deceleration of an elevator car can be produced in a number of ways known to the skilled man, e.g. by means of a metal strip stamped with perforations, the pattern of which is detected by a forked light barrier, or by magnetic pole divisions or optical reflective sections. 
         [0025]    As can be seen from the perspective views in  FIGS. 1   b  and  2   b , the two measuring strips  70 ,  90  for the two components described can be provided on the front and back of a carrier  1  (e.g., in the recess of an elevator rail), and the associated sensors  7  and  9  for the two strips  70  and  90 , respectively, can be respectively provided on the legs  42  and  40  of a U-shaped element on the elevator car. The legs  42 ,  40  surround the carrier  1  of the strips  70 ,  90  and thus allow the strips  70 ,  90  to be simultaneously read by the associated sensors  7 ,  9 . 
         [0026]    The third component is an evaluating circuit  30  as shown by way of example in  FIG. 3 . The evaluating circuit  30  may take the form of a microcontroller  10  which is electrically connected to a braking device and a catching device. The evaluating circuit  30  constitutes the core of a control device according to the invention. 
         [0027]    Attached to the microcontroller  10  are a safety relay device in the form of a first safety relay  11  and a second safety relay  12 , a braking device (not shown) and an actuator  13  connected to the first safety relay  1 , said actuator  13  actuating a catching device  14 . Shown on the left of  FIG. 3  in highly schematic form are the two measuring strips which are hereinafter referred to as the double signal strip  100 , for short, in the interest of simplicity. Shown together with double signal strip  100  are sensor devices  7  to  9 , the sensor devices  7  to  9  being mounted on the outside of the elevator car as already mentioned and travelling past the double signal strip  100  when the elevator car is in motion. 
         [0028]    For reliably detecting the speed, two redundant/diverse sensors  7  and  9  with corresponding two-channel evaluation are sufficient per se. In order to operate the elevator unit with the minimum possible disruption, a third sensor  8  may be provided according to an additional embodiment of the invention in order to detect the speed and position of the elevator car. Thus, a “2 out of 3 selection” is possible, and in this way, transitory fault signals produced by electromagnetic influences (e.g., transitory fault signals causing the unit to come to an immediate standstill) are prevented. 
         [0029]    The electrical output signals S 1  to S 3  from the sensors  7 ,  8 ,  9  are fed into the microcontroller  10 . The microcontroller  10  has a first channel A and a second channel B. Moreover, an elevator control  31  may be provided, as shown on the right in  FIG. 3 ; elevator control  31  (if provided) is separately connected to the microcontroller  10  and to the first and second safety relays  11 ,  12 . 
         [0030]    The first safety relay  11  and the second safety relay  12  are each attached to the first channel A and to the second channel B of the microcontroller  10 . The first safety relay  11  is coupled to the actuator  13  which actuates the catching device  14 ; the first safety relay  11  can thereby initiate the catching device  14 . The second safety relay  12  acts on the braking device (not shown) and can trigger the braking device when a corresponding control signal is received. 
         [0031]    Each of the channels A and B comprises three input modules  15  to  17  to which the electrical signals S 1  to S 3  of the relevant sensor devices  7  to  9  are applied. To increase the operational reliability of the apparatus, these two channels are formed with different hardware (e.g., by means of two different processors). Each channel of the microcontroller  10  may have a RAM  21 , a flash memory  22 , an EEPROM  23 , an OSC Watchdog  24 , a CAN module and individual separate input modules  15  to  17 . The hardware construction of the microcontroller  10  corresponds to a standard commercial electronic component of a kind which is industrially available, and therefore its construction and its internal computing process will not be described in more detail. 
         [0032]    The electrical signals from the two sensor devices  7  and  8  for detecting the speed are each applied to the modules  15  and  16  of a respective channel A, B. A corresponding calculation is carried out on the signals applied to the modules, from which the actual speed of the elevator car  6  can be determined. The process of determining the actual speed is restricted to a simple measurement of the time taken to travel a measured distance. If this time is greater than a reference time permanently stored in channels A and B, the speed is within a safe range. The different lengths of the measured sections, which become shorter and shorter towards the end of the shaft, also necessarily provide a direct association with the position of the elevator car. 
         [0033]    Each of the channels A and B also comprises an interface  17 , which may be constructed as a parallel or serial input. The sensor  9  connected to these inputs provides absolute positional information and further information as to the speed of the elevator car in the shaft. 
         [0034]    In the memory areas of the channels A and B, a reference speed is stored for each position in the range of deceleration distances, this reference speed having been stored by means of a calibration process when the elevator unit was installed. These reference speed values are thus dependent on the deceleration selected and the jerking of the elevator unit in question. In a simple standard unit, these values may also already be permanently programmed on delivery. This stored reference speed is compared, in the deceleration range, at every new position of the elevator car supplied by the sensors  7  to  9 , with the speed actually traveled, measured by the sensors  7  to  9 . If a fixed or adjustable tolerance threshold of the actual speed traveled is exceeded, the second safety relay  12  is actuated, thereby causing the operating brake to come into play. 
         [0035]    If a second tolerance threshold is exceeded or if the braking device fails, the first safety relay  11  is also actuated, which in turn triggers the actuator and thereby actuates the catching device for the elevator unit. 
         [0036]    All the reference values are stored in a safe storage area and are constantly monitored for their correctness using memory testing procedures known per se. To increase the operational reliability still further, the first channel A and the second channel B may be continuously compared with one another to provide a comparison of the computed variables of the first channel A and second channel B. The comparison may be used to detect differences in the electrical signals of the sensor devices  7  to  9  (e.g., due to faults) at the earliest possible opportunity. 
         [0037]    The first safety relay  11  and the second safety relay  12  are operated with separate circuits, for safety reasons. A plurality of safety relays may also be connected to each channel of the microcontroller  10 , and these safety relays are analogously operated with separate circuits. The respective safety relays  11 ,  12  are electrically connected to the individual channels A, B of the microcontroller  10 . Such connections allow channels A, B to apply control signals to the corresponding safety relays  11 ,  12 , as will be explained hereinafter, and further allow safety relays  11 ,  12  to send return feedback information to the microcontroller  10 . 
         [0038]    The first safety relay  11  is coupled to the actuator  13  which actuates the catching device  14 , as explained above. The catching device  14  may be a wedge device, known per se, which is driven between a guide rail of the elevator unit and an edge region of the elevator car in order to stop the elevator car in an emergency. When the car  6  is stationary, the actuator can also be activated and deactivated by an electrical signal for testing purposes. After the testing operation has ended, normal operation of the elevator unit can be resumed. 
         [0039]    After the braking device has been initiated by a control signal from the second safety relay  12  or after the catching device  14  has been actuated by a control signal from the first safety relay  11 , further operation of the apparatus according to the invention is not possible until an operational check has been carried out by qualified personnel. Once the check is complete, a corresponding release signal is sent from the respective safety relay  11  or  12  back to the corresponding channel A, B, after which normal travel of the elevator unit can continue. 
         [0040]    The device explained herein ensures, by means of cooperation among the double signal strip  100 , electrical components, and magnetic or optical components, effective speed limitation or speed control of the elevator car. The apparatus can thus replace conventional mechanical safety systems for speed limitation, i.e. safety buffers. Similarly, conventional electrical deceleration control circuits, which are generally used in conjunction with oil buffers in elevator units intended to operate at higher speeds, can be replaced by the safe detection of deceleration provided according to the invention. 
         [0041]    In the light of the safety concept explained above, the apparatus may meet elevator guideline requirements.