Patent Publication Number: US-2012043165-A1

Title: Elevator installation door operation

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to European Patent Application No. 10155020.0, filed Mar. 1, 2010, which is incorporated herein by reference. 
     FIELD 
     The disclosure relates to operation of a door of an elevator installation and to a corresponding elevator installation. 
     BACKGROUND 
     Elevator installations can be a significant consumer of power in a building. The overall efficiency of an elevator installation is made up of the following two essential components: energy consumption in travel operation and stand-by consumption. 
     The power consumption of an elevator installation in idle running, i.e. when traveling empty, is frequently taken into consideration. However, for overall consumption the consumption which results from journeys (termed journey energy consumption) with different load states also plays a role. 
     U.S. Pat. No. 3,365,025 shows an elevator installation in which a door keeping-open time of a elevator cage is prolonged if a person in this elevator cage has made a story selection. The possibility is thus provided for further persons to use the elevator installation for an envisaged elevator journey. 
     There are various approaches, which for example operate with energy stores for recuperation of braking energy, in order to provide some degree of reduction in energy consumption. Overall, however, there is a desire to further reduce energy consumption. 
     SUMMARY 
     In at least some cases, the disclosed technologies are based on the recognition that overall consumption can be reduced by a form of “traffic control”. In this form of traffic control, which is propagated here, the instantaneously present loading of the elevator cage can, in particular, be taken into consideration. 
     On the one hand, elevator journeys in which the elevator cage travels downwardly in an empty state or with a small load can have the consequence of high energy consumption and therefore count as inefficient trips. However, inefficient trips can also include upward journeys with a small load or with few passengers or even with only a single passenger. The reason for that can be that for a given level of upward traffic, journeys with a small load require a correspondingly higher number of trips, wherein each upward journey can have the consequence of an empty downward journey with correspondingly high energy consumption. These effects, which can arise analogously also in the case of temporary presence of downward traffic with a lightly laden elevator cage and therefore inefficient downward journeys, are explained in more detail in later sections of this description. 
     In the case of a downward journey with an empty or only lightly laden elevator cage (empty downward journey) a relatively high motor power is required, which can be equated with relatively high energy consumption associated with a specific travel distance. This is due to the fact that in the case of such an empty downward journey the counterweight is usually moved upwardly in the elevator shaft, which counterweight in most elevator installations can have a weight which is greater than the weight of the empty elevator cage. With such a design of the counterweight it can be taken into consideration that the elevator cage is typically moved at approximately 50% of the rated load. In this case the weight of the counterweight is selected to that a balanced state arises with loading of the elevator cage at 50% of the rated load. 
     In this description, it should be understood that a balanced state is a load state of the elevator installation in which the weight of the counterweight corresponds with the total weight of the elevator cage. The total weight of the elevator cage in that case comprises the empty weight of the elevator cage and the weight of a load present in the elevator cage (useful load). 
     Elevator installations can be designed so that a balanced state between elevator cage and counterweight is present when the elevator cage is loaded to, for example, approximately 50% or 40% or 30% of the rated load of the elevator cage. 
     In some embodiments, an elevator installation is operated or controlled in such a manner that as many elevator journeys as possible take place with a loading of the elevator cage in which the load state of the elevator installation corresponds as far as possible with the balanced state. The number of inefficient journeys shall thus be reduced and the number of efficient journeys increased. This is achieved by a correction or adaptation of the door keeping-open times. Before an elevator cage with a small load starts on an inefficient elevator journey, the probability of additional passengers boarding can be increased by a prolongation of the door keeping-open time. 
     That can be achieved by an operating method which can comprise the following method steps:
         providing the elevator cage on a story,   opening the elevator doors to enable loading of the elevator cage,   detecting an instantaneously present loading of the elevator cage and   adapting a door keeping-open time in dependence on the instantaneously present loading of the elevator cage.       

     By the term “instantaneously present loading of the elevator cage” is to be understood the weight of the load of the elevator cage detected by a load measuring device after elapsing of a standard door keeping-open time t sta . 
     By the term “door keeping-open time” is to be understood that period of time during which the elevator doors are, after complete opening thereof, kept open before a closing process can take place. Denoted as “standard door keeping-open time” is a fixed or settable door keeping-open time which is always used when the instantaneously present loading of the elevator cage lies above a settable predetermined value (threshold value). 
     According a variant of embodiment of the technology the door keeping-open time is adapted in accordance with the following rule:
         if the instantaneously present loading of the elevator cage lies below a settable threshold value use is made of a settable maximum door keeping-open time t max  lying above a predetermined standard door keeping-open time t sta .       

     The probability can thus be increased that at least one further passenger boards, so that the efficiency of the subsequent elevator journey and of the entire elevator operation is improved. Possibly, the threshold value is settable within a load range lying between zero load and the load for the balanced state. 
     According to a variant of embodiment of the method the door keeping-open time is adapted in accordance with the following rule: if the instantaneously present loading of the elevator cage lies below a settable threshold value, use is made of a variable door keeping-open time t var , the duration of which lies between a settable maximum door keeping-open time t min  and a settable maximum door keeping-open time t max  and is substantially inversely proportional to the instantaneously present loading. 
     The door keeping-open times t max  and also t min  in that case both lie above the standard door keeping-open time t sta . 
     Through the use of this method the probability can similarly be increased that at least one further passenger boards, so that the efficiency of the subsequent elevator journey and also of the further operational sequence influenced by this elevator journey is improved. The door keeping-open time is in this embodiment optimized by adaptation to the degree of under-loading of the elevator cage. The threshold value can be settable within a load range lying between zero load and the load in the balanced state. 
     According to a further embodiment of the method use is made of a so-termed standard door keeping-open time t sta  when the instantaneously present loading of the elevator cage exceeds the settable threshold value. 
     According to a further embodiment of the method use is made of a so-termed standard door keeping-open time t sta  when the instantaneously present loading of the elevator cage corresponds approximately with the load in the balanced state or a greater load, i.e. when the weight of the current load (for example, approximate 50% of the rated load) together with the empty weight of the elevator cage corresponds approximately with the total weight of the counterweight or an even higher weight. 
     According to an embodiment of the method the possibility of a passenger, who has boarded, being able to cause premature door closing by actuation of a signal transmitter, for example a button, is suppressed. It is thus achieved that an extension of the door keeping-open time cannot be prevented by passengers. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The technologies are further explained in the following by several exemplifying embodiments with reference to the figures. 
         FIG. 1A  shows a simplified illustration of an elevator installation in a first load state during a downward journey (journey in empty state); 
         FIG. 1B  shows a simplified illustration of an elevator installation according to  FIG. 1A  in a first load state during an upward journey (journey in empty state); 
         FIG. 2A  shows a simplified illustration of the elevator installation according to  FIG. 1A  in a second load state during a downward journey (journey in balanced state); 
         FIG. 2B  shows a simplified illustration of the elevator installation according to  FIG. 1A  in a first load state during an upward journey (journey in balanced state); 
         FIG. 3A  shows a simplified illustration of the elevator installation according to  FIG. 1A  in a third load state during a downward journey (journey in a part-load state); 
         FIG. 3B  shows a simplified illustration of the elevator installation according to  FIG. 1A  in a third load state during an upward journey (journey in a part-load state); and 
         FIG. 4  shows an illustration of a further elevator installation with a block-diagram illustration of the elevator control. 
     
    
    
     DETAILED DESCRIPTION 
     For explanation of the present disclosure the energy consumption per journey is determined in the following simplified form. These are merely examples of counting, which serve for explanation. In the case of actual use the count values can be established with consideration of the actual elevator constellation. 
     The starting point is an elevator installation  1  as illustrated in  FIG. 1A . This is an elevator installation  1  with an elevator cage  10 , elevator doors  15  (cage and shaft doors) and a counterweight  13 , which moves in opposite direction to the elevator cage  10 . A drive  20  drives, by way of a drive pulley  21 , a support means  11  by which the elevator cage  10  and the counterweight  13  are connected together, carried and driven. 
     In order to be able to illustrate in simple mode and manner how the energy consumption of an elevator installation can be reduced, there will be assumed a configuration in which the elevator cage  10  has an empty weight LG=100 GE (GE=units of weight). One GE can be, for example, 1 kilogram. The counterweight  13  here has a weight GG=150 GE. 
     Not taken into consideration in the following examples are influencing variables such as friction, slip, stand-by consumption, energy consumption in door opening and closing, and other factors. The concern in the following is primarily the journey energy consumption which results from the upward and downward movement of masses (weights), i.e. primarily consideration of changes in the potential energies of the elevator cage and the counterweight. 
     A situation is shown in  FIG. 1A  (1st case) in which the elevator cage  10  is in the course of a downward journey AB. The elevator cage  10  is empty, i.e. this is an empty downward journey. Since at the same time the counterweight  13  has to be moved upwardly, an energy equivalent of 50 EE (EE=unit of energy) is expended here for a specific travel distance, since 150 GE (of the counterweight) are moved upwardly and 100 GE (of the elevator cage) are moved downwardly. The value of a unit of energy EE can be indicated, for example, in kWh. Here these are not absolute considerations, but relative considerations. 
     A situation is shown in  FIG. 1B  (2nd case) in which the elevator cage  10  is in the course of an upward journey AUF. The elevator cage  10  is empty, i.e. it is an empty upward journey. Since at the same time the counterweight  13  has to be moved downwardly, here there is no expenditure of drive energy (energy equivalent of 0 EE), since the counterweight  13  is heavier than the empty weight of the elevator cage. In this case it can even be possible to recover energy if, for example, an energy recuperation system is present. 
     A situation is shown in  FIG. 2A  (3rd case) in which the elevator cage  10  is in the course of a downward journey AB. The elevator cage  10 , with its empty weight of 100 GE, is laden with a useful load of 50 GE. Since at the same time the counterweight  13  with its 150 GE has to be moved upwardly, there is here a balanced journey. No drive energy is expended for the journey (energy equivalent of 0 EE). Here, for example, four passengers are located in the elevator cage  10 , the total weight (useful load) of which corresponds with 50 GE. 
     A situation is shown in  FIG. 2B  (4th case) in which the elevator cage  10  is in the course of an upward journey AUF. The elevator cage  10 , with its empty weight of 100 GE is laden with a useful load of 50 GE. Since at the same time the counterweight  13 , with its 150 GE, is moved downwardly, there is similarly a balanced journey here. No drive energy is expended (energy equivalent of 0 EE) for the journey, since the counterweight  13  is as heavy as the elevator cage  10  with the useful load of 50 GE. 
     A situation is shown in  FIG. 3A  (5th case) in which the elevator cage  10  is in the course of a downward journey AB. The elevator cage  10  is laden with a useful load of 25 GE, i.e. there is a downward part-load journey AB in which the total weight of the elevator cage  10  (100 GE+25 GE) is smaller than the weight GG of the counterweight of 150 GE. This load situation is termed part-load state. Since the counterweight  13  with its 150 GE has to be moved upwardly, here an energy equivalent of 25 EE is expended for the stated specific travel distance. Here, by way of example, two passengers are located in the elevator cage  10 , the total weight of which corresponds with 25 GE. 
     A situation is shown in  FIG. 3B  (6th case) in which the elevator cage  10  is in the course of an upward journey AUF. The elevator cage  10  is laden with a useful load 25 GE (part-load state), i.e. there is an upward part-load journey AUF in which the total weight of the elevator cage  10  (100 GE+25 GE) is smaller than the weight GG of the counterweight of 150 GE. Since in the case of the part-load upward journey of the elevator cage  10  the counterweight  13  is moved downwardly at the same time, no drive energy is expended here (energy equivalent of 0 EE), since the counterweight  13  is heavier than the elevator cage with the useful load. In this case as well energy can be recovered if the elevator installation is equipped with an energy recuperation system. 
     In cases  2 ,  3 ,  4  and  6  no energy is expended (according to simplified calculations), since in an upward journey AUF of the elevator cage  10  either the counterweight  13  is at least as heavy as the total weight of the elevator cage  10  or since, in the case of a downward journey AB of the elevator cage  10 , the elevator cage  10  with the instantaneously present loading has the same weight as or is heavier than the counterweight  13 . In the other cases  1  and  5 , energy is expended. 
     It is of interest to establish on the basis of this simplified form of calculation that in cases  1  and  5  the expenditure of energy for a defined travel distance is proportional to the instantaneous weight difference between the total weight of the elevator cage and the weight of the counterweight (in the 1st case 50 GE and in the 5th case 25 GE). This also applies to actual elevator installations  1 . 
     It is also of interest to establish that a positive expenditure of energy (i.e. an energy consumption) usually arises when the counterweight  13  is transported upwardly, i.e. in the case of a downward journey AB of the elevator cage  10 . However, this applies only when the elevator cage  10  is not more heavily laden than in the case of a balanced travel. 
     In some cases, it can be assumed that the number of journeys in empty state or inefficient journeys (such as, for example, the cases  1  and  5 ) are kept as small as possible and the number of efficient journeys (such as, for example, the cases  2 ,  3 ,  4 ,  6 ) are to be maximized as far as possible. 
     However, in that case it can be taken into consideration that, for example, with the start of the work day and its predominantly upward traffic incidence in an office building, usually a downward, empty journey follows an upward journey of the elevator cage  10  in order to make the elevator cage  10  available again at the lowermost story  12 . u , so that further persons can be transported upwardly. At the end of the work day, with predominantly downward traffic incidence, the elevator cage  10 , typically laden from one of the upper stories, will travel downwardly; and, consequently, upwardly again from below in the empty state. It can therefore be assumed in numerous operational situations that the journeys with laden cage have the consequence on each occasion of a journey in empty state with highest possible expenditure of energy. 
     Measures can be undertaken to have the effect that elevator journeys take place as often as possible with loading of the elevator cage, which as far as possible approaches loading for a balanced journey. Thus, it can be achieved on the one hand that a significant part of the elevator journeys is performed in each instance with smallest possible energy consumption. On the other hand, at the same time, a reduction of the total number of elevator journeys required for a given level of traffic is achieved in that it is sought as far as possible to avoid elevator journeys with an inefficient, small number of passengers. 
     According to some embodiments, such a measure comprises that at a stop of the elevator cage  10  at a story  12 . o ,  12 . u  the door keeping-open time of the elevator doors  15  is controlled in dependence on the detected instantaneously present useful load in the elevator cage  10 , i.e. in dependence on the detected loading situation of the elevator cage. Stated in simple terms, in the case of a detected small loading (useful load) of the elevator cage  10  an extended door keeping-open time shall come into use after expiry of the standard door keeping-open time T sta . The probability can thus be increased that in the case of instantaneous small loading still further passengers board before the elevator doors close and the journey of the elevator cage begins. The probability can thus also be increased that a substantial part of the elevator journeys can be carried out with an energy consumption which is smaller than in the case of an elevator journey with, for example, a single passenger. In particular, however, the probability can also be increased that the entire level of traffic can be managed with a smaller number of elevator journeys, whereby also a smaller number of energy-consuming return journeys in empty state results. 
     On the basis of the considerations explained in the foregoing the following rules can be established for the drive control, i.e. for operation of the elevator installation  1 .
         Rule 1:   In the case of an elevator cage  10  which has stopped at a story  12 . o ,  12 . u  and opened the elevator doors  15 , a settable maximum door keeping-open time t max  lying above a predetermined standard door keeping-open time t sta  comes into use if the instantaneously present loading of the elevator cage  10  lies below a settable threshold value.       

     Through the use of this first Rule the probability can be increased that further passengers board and the elevator cage  10  does not begin its intended journey with a minimum load. In this manner the number of journeys with a small load (for example, with a single passenger) and high energy consumption and as a consequence also the number of return journeys in empty state with highest energy consumption can be reduced. 
     According to some embodiments, thus prior to each journey after expiry of a standard door keeping-open time t sta  the instantaneously present loading of the elevator cage  10  is detected. Adaptation of the door keeping-open time takes place on the basis of this information.
         Rule 2:   In the case of an elevator cage  10  which has stopped at a story  12 . o ,  12 . u  and opened the elevator doors  15 , if the instantaneously present loading of the elevator cage  10  lies below a settable threshold value, use is made of a variable door keeping-open time t var , the duration of which lies between a settable minimum door keeping-open time t min  and a settable maximum door keeping-open time t max  and is substantially inversely proportional to the instantaneously present loading.       

     This Rule is advantageous to the extent that the elevator doors remain open longer the smaller the instantaneously present loading of the elevator cage, which increases the probability that the elevator cage does not have to execute its intended journey with an extremely low loading. Moreover, a maximum door keeping-open time does not come into use if an instantaneous loading is present which is relatively high, but which still lies below the threshold value.
         Rule 3:   In the case of an elevator cage  10  which has stopped at a story  12 . o ,  12 . u  and opened the elevator doors, the standard door keeping-open time t sta  or a standard door keeping-open time t sta  unchanged comes into use if the instantaneously present loading of the elevator cage  10  exceeds a settable threshold value.   Rule 4:   In the case of a elevator cage  10  which has stopped at a story  12 . o ,  12 . u  and opened the elevator doors, the predetermined standard door keeping-open time t sta  comes into use unchanged if the instantaneously present loading of the elevator cage  10  approximately corresponds with loading in the balanced state or an even higher loading.       

     These Rules  1  to  4  can be filed or implemented in a elevator control  30  and/or in a special module  31 . 
     Depending on the respective form of embodiment, detection of the load situation of the elevator cage  10  is carried out by interrogation or evaluation of a load detector  16  of the elevator cage  10  and/or by an indirect detection of the load situation of the elevator cage  10 . In the case of indirect detection the number of persons who have entered or left the elevator cage  10  is detected in order to be able to draw a conclusion about the load situation. This can be carried out, for example, by means of a light barrier or a camera-based recognition of persons. It is also conceivable to detect the current load situation in buildings with protected access by contactless reading of proof of identity which every person carries. 
     These two methods can also be combined in order to be able to make a more precise statement with respect to a load situation. 
     The method by way of a load detector  16  is preferred, since such a detector  16  is typically present in every elevator cage  10  in order to, for example, be able to recognize an impermissible over-loading of the elevator cage  10 . 
     Details of a form of embodiment of an elevator installation are shown in  FIG. 4 . The details of  FIG. 4  can apply to all other embodiments. An elevator control  30  is shown, which monitors the operation of the elevator installation  1  or controls the elevator installation  1 . For this purpose there is a connection or link  32  between the elevator control  30  and the drive  20 . A further connection or link  33  ensures that the elevator control  30  can obtain a request signal or a travel direction preset from a control panel (not shown) in the elevator cage  10  or at the elevator shaft  14 . The load detector  16  supplies, by way of a connection or link  34 , to a door control module  31  information about the instantaneous load situation of the elevator cage. The door control module  31  has interaction  35  with the elevator control  30  in order to enable the exchange of information with the elevator control  30  or monitoring by the elevator control. The door control module  31  establishes the door keeping-open time (for example t sta , t max  or t var ) which comes into use at that moment. For this purpose it can comprise a timing element or a counter  36  in order to initiate closing of the elevator doors  15  on reaching the door keeping-open time. For this purpose the door control module  31  can switch off, for example, a voltage supply of the door drives (not shown) or supply a pulse to the door drives as illustrated in simplified form in  FIG. 4  by the connection/link  37 . 
     The standard door keeping-time t sta  and/or the respective extended maximum door keeping-open time t max  to be used and/or the variable door keeping-open time t var  can be filed in a memory  38  which, for example, is linked with the elevator control  30 , as shown in  FIG. 4 . 
     In another embodiment the possibility is suppressed that a passenger in a elevator cage can cause premature door closing by, for example, actuation of an appropriate button. It can thereby be achieved that an advantageous prolonging of the door keeping-open time cannot be prevented by the passengers. 
     As already mentioned, in some embodiments an elevator installation  1  can be so operated, i.e. so controlled, that the number of inefficient journeys is reduced and the number of efficient journeys increased. In accordance with at least some embodiments of the disclosed technologies this is achieved in that the door keeping-open times, i.e. the times during which the elevator doors  15  stay open, are variable in dependence on the load situation. It is obvious that the level of traffic has no influence or has an influence only to limited extent. However, through the measures of the disclosed technologies it is possible to achieve, under the respectively given circumstances, an optimization with respect to energy consumption, which leads to a detectable saving of energy. 
     For explanation of the disclosed technologies, illustration has been made of so-called cable elevators which comprise a support means  11  carrying and driving a elevator cage  10 . However, the disclosed technologies are also applicable to hydraulic elevators with or without a counterweight. 
     Having illustrated and described the principles of the disclosed technologies, it will be apparent to those skilled in the art that the disclosed embodiments can be modified in arrangement and detail without departing from such principles. In view of the many possible embodiments to which the principles of the disclosed technologies can be applied, it should be recognized that the illustrated embodiments are only examples of the technologies and should not be taken as limiting the scope of the invention. Rather, the scope of the invention is defined by the following claims and their equivalents. I therefore claim as my invention all that comes within the scope and spirit of these claims.