Patent Grant
8863908
This application claims priority to European Patent Application No. 10175981.9, filed Sep. 9, 2010, which is incorporated herein by reference.
The disclosure relates to controlling a drive motor of an elevator installation.
Methods of controlling the drive motor of elevator installations can differ, for example, in the form of speed control and in the form of detection of the position of the elevator cage.
In the case of elevator installations for high demands with respect to travel speed and transport capacity the position of the elevator cage can be detected by an absolute position measuring system, which supplies to the elevator control information, from which the elevator control recognizes the current position of the elevator cage. The travel speed is regulated in correspondence with a trip/speed profile, the course of which is determined in dependence on the trip distance between a start position and a destination position before the start of the trip.
In the case of elevator installations for moderate demands with respect to travel speed and transport capacity the position of the elevator cage is often detected by a position detection system with a travel transmitter. Such a travel transmitter is often constructed as an incremental rotary encoder and is driven by the movement of the elevator cage by means of a transmission mechanism. In one often-employed form of embodiment, an incremental rotary encoder is coupled with the rotating axle of the cable pulley of a speed limiter, wherein a wire cable transmits the movement of the elevator cage to the cable pulley of the speed limiter and thus forms the mentioned transmission mechanism.
A travel transmitter supplies to the elevator control signals from which the elevator control can derive trip distances, speed and acceleration of a movement of the elevator cage. The information about the position of the elevator cage can be detected by summation of the detected trip distances. It can therefore be falsified or lost, for example as a consequence of disturbances in the signal transmission or interruptions in the power supply, which can require measures for reinstatement of the correct position in the position detecting system.
Such a position detecting system for an elevator cage of an elevator installation is known from WO 01/70613. In the described equipment the elevator control registers the current position of the elevator cage over the entire trip distance on the basis of signals of an incremental rotary encoder coupled with the cable pulley of a speed limiter and thus with the movement of the elevator cage. However, noise pulses and, in particular, slips in the cable drive coupling the movement of the elevator cage with the incremental rotary encoder produce deviations between the instantaneously registered position of the elevator cage ascertained on the basis of the signals of the incremental rotary encoder and the actual instantaneous cage position. In order to provide compensation for the effect of such disturbing influences, the instantaneously registered position of the elevator cage is corrected on arrival of the elevator cage at a destination stopping point and/or movement past intermediate stopping points. This is carried out in that, with the help of a stopping point sensor mounted on the elevator cage, a respective stopping point marking associated with a specific stopping point is detected, whereupon the position of the elevator cage instantaneously registered in the elevator control is corrected in correspondence with the stored stopping point position value associated with the respective stopping point. Moreover, the elevator control is conceived so that a stored stopping point position value is corrected when this gives repeated cause for significant corrections, which are effective in the same direction, of the instantaneously registered position of the elevator cage.
In the cited prior art, in which the slip corrections are undertaken only on reaching the stopping point marking of the destination stopping point, the movement of the elevator cage into the region of the stopping point marking has to be carried out at reduced travel speed. This is due to the fact that the slip arising in the coupling between the movement of the elevator cage and the movement of the incremental rotary encoder can lead to such a large deviation of the instantaneously registered elevator cage position from the actual instantaneous elevator cage position that the position-dependent travel speed, which is present on movement of the elevator cage into the region of the stopping point marking of the destination stopping point, of the elevator cage can be so high that braking until reaching the destination stopping point position is no longer possible. Such a situation leads to disruptions of the normal operation and can even lead to shutdown of the elevator installation. The stated slip-dependent deviation can, however, also be of such a kind that the travel speed of the elevator cage present when the elevator cage moves into the region of the stopping point marking of the destination stopping point is already too low, so that in order to reach the destination stopping point position an extended trip at low speed and correspondingly increased journey time is required.
At least some embodiments of the disclosed technologies comprise a method, which can be optimized with respect to travel time, for controlling a drive motor of an elevator installation. Further embodiments comprise a method that does not require additional travel transmitters for direct detection of the movement of the elevator cage.
Some embodiments comprise a method of controlling a drive motor of an elevator installation, in which elevator installation an elevator cage can be moved along a trip path by the drive motor by way of a drive pulley and at least one flexible support means and stopped at stopping point positions of a plurality of stopping points. In that case, movement of the elevator cage is detected by a drive control on the basis of signals of a rotary encoder coupled with a rotational movement of the drive motor or the drive pulley and, before the start of travel of the elevator cage, a movement plot in the form a trip/speed profile for a journey of the elevator cage from an instantaneous elevator cage position to a destination stopping point position is calculated by an elevator control, wherein an anticipated slip between the drive pulley and the support means is calculated into the computation of the trip/speed profile so as to be able to aid in maintenance of the calculated movement plot notwithstanding slip. During travel of the elevator cage a rotational movement of the drive motor and thus the drive pulley is controlled by the elevator control in dependence on the calculated trip/speed profile and on signals of the rotary encoder.
By the term “support means” is to be understood in the present disclosure flexible traction means in the form of, for example, steel wire cables, flat belts, wedge-ribbed belts or link chains suitable for carrying and driving an elevator cage and a counterweight.
By the term “elevator control” is to be understood, for example, all control components participating in the control of the elevator installation regardless of their function and arrangement in the elevator installation.
Suitable as rotary encoder are devices in which the rotational movement of the drive motor is detected by, for example, scanning of apertured discs, slotted discs, graduated discs or magnetic pole discs, wherein the scanning can be carried out by means of, for example, light barriers, laser reflection scanners, inductive sensors or magnetic sensors.
In at least some embodiments, the incremental rotary encoder, which is sometimes required in prior art, and which is coupled with the cable pulley of the speed limiter, for detection of movement of the elevator cage, can be saved. Also saved can be the device for evaluating this incremental rotary encoder, as well as the outlay on installation thereof. This is achieved in that for detection of movement of the elevator cage use can be made of the signals of a rotary encoder already present for regulation of the rotational speed of the drive motor. However, this rotary encoder detects the rotational movement of the drive motor or the drive pulley.
The information, which is supplied by it, about the movement of the elevator cage can therefore be subject to an error caused by slip between drive pulley and support means and dependent on the cage loading and the travel direction.
Through the calculation and predetermination of a slip-corrected trip/speed profile it is made possible to carry out journeys of the elevator cage between an instantaneous elevator cage position and a destination stopping point in shortest possible travel time, i.e. with an optimum trip/speed profile. The taking of the anticipated slip into consideration in the calculation of the trip/speed profile can mean that the elevator cage on reaching the destination stopping point, i.e. on detection of the start of a stopping point marking associated with the destination stopping point, has with greater accuracy the optimum travel speed computed for this situation. This optimum travel speed can be that speed at which braking of the elevator cage at permissible retardation values is still safely possible within a travel distance, which corresponds with half the length of the stopping point marking, up to the correct stopping point position.
According to an embodiment of the method, before start of travel of the elevator cage an actual trip distance between an instantaneous elevator cage position and a destination stopping point position is calculated by the elevator control on the basis of the known stopping point position values registered in the elevator control, a slip-corrected trip distance is calculated on the basis of this actual distance and the anticipated slip between the drive pulley and the support means and the trip/speed profile for travel of the elevator cage from the instantaneous elevator cage position until reaching the destination stopping point position is calculated on the basis of this slip-corrected trip distance. Through calculation of the anticipated slip into the trip distance calculated for the intended journey of the elevator cage, and thus into the calculation of the trip/speed profile optimized for this trip distance, one of the preconditions for reaching the stopping point marking of the destination stopping point with the highest possible travel speed calculated for this situation and thus for a shortest possible journey time is fulfilled.
According to a further embodiment of the method, the stopping point positions are characterized by stopping point markings and the stopping point markings are detected by at least one stopping point sensor mounted on the elevator cage, wherein the stopping point markings of all stopping points as measured in the travel direction of the elevator cage are formed to be of equal length and at least of sufficient length for stopping of the elevator cage within half the length of the stopping point markings to be possible, and the stopping point markings and the stopping point sensor are so arranged that a cage floor of the elevator cage is disposed at a level of a stopping point position when the elevator cage in upward travel or downward travel after detection of a start of a stopping point marking is still moved on by half the length of the stopping point marking. With such a form of a method a sufficiently precise positioning of the elevator cage relative to the stopping points can be realized particularly simply and economically.
According to a further embodiment of the method, the drive motor is so controlled during travel of the elevator cage that the elevator cage is moved in correspondence with the calculated trip/speed profile from the instantaneous elevator cage position until reaching a stopping point marking of an intermediate stopping point or a destination stopping point, wherein on reaching such a stopping point marking, a correction of the instantaneous elevator cage position registered in the elevator control and a corresponding correction of the trip/speed profile for the residual distance still to be covered by the elevator cage up to the destination stopping point position are carried out. In at least some cases, this allows for an improved likelihood of reaching the stopping point marking of the destination stopping point at the optimum travel speed calculated for this situation. Termed as intermediate stopping points in the present disclosure are those stopping points the elevator cage passes on its route from its instantaneous position to a destination stopping point associated with the current journey.
According to a further embodiment of the method, slip factors of different size, the magnitude of which is dependent on a cage loading present in the case of the respective journey of the elevator cage, are calculated into the calculation of the slip-corrected travel distance.
In at least some embodiments, through the use of slip factors having a magnitude which has been ascertained for journeys of the elevator cage with cage loads of different levels, the accuracy and efficiency of the method according to the invention are further optimized.
According to a further embodiment of the method, the placing into operation of an elevator installation operated in accordance with the method comprises ascertaining all stopping point positions. This takes place in that when the elevator installation is placed in operation a learning trip of the elevator cage, possibly without a cage load, is performed in which the stopping point position values of all stopping points are ascertained and registered. After conclusion of the learning trip, a learning trip slip factor is ascertained and the registered stopping point position values are corrected in dependence on the ascertained learning trip slip factor. This process makes it possible to register all stopping point position values of a newly installed elevator installation with sufficient accuracy and small expenditure of time, even though the coupling of the rotary encoder with the movement of the elevator cage is subject to slip.
According to a further embodiment of the method, the learning trip is executed without a cage load or with a cage load of less than 30% of the rated load. This method variant, which is realizable thanks to the slip correction, can save the laborious loading and unloading of the elevator cage for performance of the learning trip.
According to a further embodiment of the method, the elevator cage in the case of the learning trip initially executes an outward journey in upward or downward direction, in which a stopping point sensor mounted on the elevator cage initially detects a zero position marking and subsequently the stopping point markings of all stopping points, and subsequently the elevator cage executes a return journey, in which the stopping point sensor again reaches and detects the zero position marking. In the case of detection of a respective one of the stopping point markings by the stopping point sensor on the outward journey a travel distance, which is detected by the rotary encoder, from the zero position marking up to the start of the detected stopping point marking is then corrected by half the length of the stopping point marking and registered as stopping point position value. This embodiment of the method can enable a simple and time-saving detection of the stopping point position values of all stopping points of the elevator installation.
According to a further embodiment of the method, the afore-mentioned learning trip slip factor is ascertained in that the travel distance between a defined point in the region of the start of the outward journey and a reversal position of the end of the outward journey is detected on the basis of the signals of the rotary encoder, the travel distance between the reversal position at the end of the outward journey and the defined point in the region of the start of the outward journey is detected on the basis of the signals of the rotary encoder, and after the learning trip has been concluded a difference between the two detected travel distances—which difference represents the total slip occurring during the outward and return journeys—is divided by the total travel distance detected in the outward and return journeys. This embodiment of the method can enable an extremely simple determination of a learning trip slip factor, by which the stopping point position values ascertained by a measurement subject to slip can be corrected.
According to a further variant of embodiment of the method—as a basis for the calculation of the anticipated slip into the calculation of the trip/speed profile—actual value slip factors dependent on the instantaneous cage loading are determined. This is carried out in that after journeys of the elevator cage in normal operation of the elevator installation on each occasion a first value for a defined travel distance between the start stopping point and the destination stopping point is ascertained on the basis of the signals of the rotary encoder, a second value for the defined travel distance is ascertained on the basis of the registered stopping point position values of the start stopping point and the destination stopping point, and the quotient of the first and the second values is dynamically stored as actual value slip factor in association with one of a plurality of cage loading ranges, wherein for determination of this association the cage loading present in the respective journey of the elevator cage is detected by the elevator control. By the term “defined travel distance” is understood a travel distance precisely detectable by the stopping distance sensor and known or calculable from the results of the learning trip, for example a distance, which is detected by the stopping point sensor and on the other hand calculable from the stopping point positions, between the end of the stopping point marking of the start stopping point and the start of the stopping point marking of the destination stopping point. Such an embodiment of the method forms the basis for further embodiments, in which by way of a load-dependent slip factor a calculated actual travel distance between an instantaneous elevator cage position and a destination stopping point position of a journey to be carried out is corrected, wherein the corrected travel distance then forms the basis for calculation of the trip/speed profile for control of the drive motor during travel of the elevator cage.
By the term “dynamically stored” is understood in the present context a storage of values according to the FIFO (first in-first out) principle. In this principle, for example, the values of respectively recalculated actual value slip factors are registered in a first memory line in, for example, a FIFO memory comprising a series of memory lines, wherein the existing contents of all memory lines are displaced by one position in the series and the content of the last storage location is lost.
According to a further embodiment of the method, each of the calculated actual value slip factors is stored in association with one of a plurality of cage loading ranges or not only with one of a plurality of cage loading ranges, but also with one of the two travel directions, wherein the association is carried out in correspondence with the cage loading or the travel direction which was present in the journey of the elevator cage in which the respective actual value slip factor was ascertained. A basis is thus created for making available load-dependent slip factors by which the trip/speed profiles of future journeys of the elevator cage can be calculated with consideration of the anticipated slip between the drive pulley and the support means.
According to a further embodiment of the method, the elevator control comprises a table memory in which a table column is associated with one of a plurality of cage loading ranges or not only one of a plurality of cage loading ranges, but also one of the two travel directions, wherein the actual value slip factors calculated after journeys of the elevator cage are dynamically stored in that respective one of the table columns which is associated with that cage loading range or that travel direction which includes the cage loading or travel direction present in the respectively concluded journey of the elevator cage. It is achieved by such a form of the method that actual value slip factors ascertained in conjunction with a specific cage loading range can be stored in association with the corresponding cage loading range so that they can be called up after further processing for calculation of trip/speed profiles of future journeys of the elevator cage with the same cage loading range.
According to a further embodiment of the method, in each instance a limited number of last-calculated actual value slip factors, respectively associated with one of the table columns, is dynamically stored in the table columns, a mean value for the load-dependent slip factors stored therein is periodically calculated for each of the table columns and these mean values are made available as information in the form of current load-dependent slip factors for calculation of trip/speed profiles for movements of the elevator cage from a respective instantaneous elevator cage position until reaching a destination stopping point position. The periodic determination of mean values of the last-stored actual value slip factors each associated with a respective cage loading range can make it possible to make available current load-dependent slip factors, which take into consideration not only the currently present cage loading, but also changes over time of the slip occurring between drive pulley and support means.
According to a further embodiment of the method, during a journey of the elevator cage an instantaneously registered elevator cage position is continuously ascertained in the elevator control by way of the signals of the rotary encoder, and on the basis of the instantaneously registered elevator cage position and the trip/speed profile calculated before the travel of the elevator cage, the instantaneous rotational speed of the drive motor or the drive pulley is controlled by the elevator control, wherein on detection of stopping point marking of an intermediate stopping point lying between a start stopping point and the destination stopping point a correction of the instantaneously registered elevator cage position is carried out on the basis of the stopping point position value associated with this stopping point marking in the learning trip.
In some embodiments, in the case of long journeys of the elevator cage over several stopping points the deviations, which still arise despite slip compensation, between the instantaneously registered and the actual elevator cage position are not summated.
According to a further embodiment of the method, after correction of the instantaneously registered elevator cage position, the travel distance between the instantaneously registered elevator cage position and the destination stopping point position is recalculated and corrected by the current load-dependent slip factor, and on the basis of the recalculated travel distance corrected by the current load-dependent slip factor a new trip/speed profile for travel of the elevator cage from the instantaneously registered elevator cage position to the destination stopping point position is calculated. A further reduction in the deviation of the travel of the elevator cage from an optimum trip/speed profile can thereby achieved.
Exemplifying embodiments are explained in the following on the basis of the accompanying drawings, wherein:
An elevator installation 1, which can be used with at least some of the disclosed embodiments for controlling the drive motor, is illustrated in
The elevator shaft has several shaft accesses, which are usually each associated with a respective story of a building and which are termed stopping points 7. In operation of the elevator installation the elevator cage 3 is moved by the drive motor 8 in each instance from an instantaneous elevator cage position—usually from a stopping point position 18 associated with a stopping point 7—at which the elevator cage is instantaneously disposed to a stopping point position 18 associated with another stopping point 7. In that case the rotational movement of the drive motor 8 is controlled or regulated by an elevator control 10 in such a manner that a journey of the elevator cage 3 is performed in, for example, the shortest possible time, i.e. requires a smallest possible journey time. This is achieved in that the elevator control 10 before each travel of the elevator cage 3 calculates a suitable trip/speed profile for the journey to be performed. An optimum plot of this trip/speed profile can be on the one hand dependent on invariable technical specifics such as permissible acceleration, permissible deceleration and maximum speed and on the other hand on situation-dependent influencing factors. In at least some embodiments, the most important situation-dependent influencing factor is the length of the journey of the elevator cage to be carried out, i.e. the distance between the start stopping point and the destination stopping point or between the instantaneous elevator cage position and the destination stopping point position. In addition, the current cage loading could enter into the calculation of the trip/speed profile as, for example, a situation-dependent influencing factor.
In order to be able to realize a movement of the elevator cage 3 in accordance with the calculated trip/speed profile, the rotational speed of the drive motor 8 can regulated by means of a regulating device belonging to the elevator control 10. In order to be able to operate this regulating device as a closed regulating circuit, a movement sensor is sometimes required for reporting the movement data of the drive motor to the regulating device. In the present exemplifying embodiment such a movement sensor is present in the form of an incremental rotary encoder 12 coupled with the motor shaft of the drive motor 8 or with the drive pulley 9.
Moreover, mounted on the elevator cage 3 is a stopping point sensor 15, which, in the case of traveling past or stopping at one of the stopping points 7, the start of a stopping point marking 13 associated with the respective stopping point is detected. The stopping point markings 13 and the stopping point sensor 15 are so positioned that the elevator cage 3 is disposed at the stopping point position associated with the respective stopping point 7, i.e. at a position in which the floor of the elevator cage and the floor of the stopping point lie at the same level, after the elevator cage has been moved in upward travel or downward travel—following detection of the start of the associated stopping point marking 13 as considered in travel direction—additionally by half the known length of the stopping point marking 13. Insofar as this condition is fulfilled, the arrangement of the stopping point sensor 15 in vertical direction at the elevator cage 3 can be freely selected.
A trip/speed profile 20.1 of a journey of the elevator cage 3 over a relatively large travel distance is illustrated in
An exemplary trip/speed profile 20.2 of a journey of the elevator cage 3 over a relatively short travel distance is illustrated in
It can be possible to derive from the signals of the incremental rotary encoder 12 at any time not only the movement data of the drive motor 8 and the drive pulley 9, but theoretically also the movement data of the support means 5 and thus of the elevator cage 3. In particular, the elevator control 10 can ascertain and register the instantaneous elevator cage position by evaluation of the signals of the incremental encoder 12 and summation of the travel distances derived therefrom. In the following, the instantaneous elevator cage position registered in the elevator control is termed “instantaneous registered elevator cage position”. In fact, however, the transmission of movement from the drive pulley 9 to the support means 5 and thus to the elevator cage 3 is subject to slip, wherein the magnitude of this slip is dependent on the cage loading present during a journey and on friction values, which change with time, between the drive pulley and the support means. However, the coupling of the movement of the incremental rotary encoder with the movement of the elevator cage is thus also subject to slip. Without corrective measures, impermissibly large deviations of the instantaneously registered elevator cage position from the actual instantaneous position of the elevator cage 3 would arise during operation of the elevator installation as a consequence of this slip.
A first exemplary measure for avoidance of impermissibly large deviations between the instantaneously registered and the actual instantaneous elevator cage position is explained on the basis of
This first measure thus includes correcting the elevator cage position 16, which is instantaneously registered in the elevator control 10, on each movement of the elevator cage past one of the stopping points 7 in that the known stopping point position value, which is stored in the elevator control 10, of the respective stopping point is registered as a new instantaneously registered elevator cage position 16. For this purpose all stopping points 7 are provided with a respective stopping point marking 13, wherein all stopping point markings have a uniform length as considered in travel direction of the elevator cage and are arranged at the same level relative to the respectively associated stopping points 7. The stopping point sensor 15 mounted on the elevator cage 3 detects, during travel past or stopping at a stopping point, the respective start of the associated stopping point marking 13. This situation is illustrated in
Alternatively, instead of detection of the start, as considered in travel direction of the elevator cage, a stopping point marking the end thereof can be detected. In order to ascertain the instantaneously registered elevator cage position 16, in this case the spacing, which corresponds with half the length of the stopping point marking 13, from the associated stopping point position in upward travel, i.e. in positive travel direction, is to be added to the known stopping point position value and to be subtracted therefrom in the case of downward travel.
In the situation shown in
In the situation shown in
After (e.g., directly after) correction of the instantaneously registered elevator cage position 16 has been carried out, the trip/speed profile 20.1, 20.2 (
Such a correction of the instantaneously registered elevator cage position 16 by appropriate adaptation of the trip/speed profile for the remaining residual distance for travel of the elevator cage to the destination stopping point position 18 usually takes place during travel past each intermediate stopping point. Alternatively, such an adaptation can be additionally carried out on reaching the start of the stopping point marking 13 of the destination stopping point.
In a further alternative embodiment, in each instance on detection of a start, as considered in travel direction of the elevator cage, of a stopping point marking 13 the afore-described correction of the stopping point position value can be undertaken, and in the case of subsequent detection of the end of the stopping point marking 13 the remaining residual distance of the travel of the elevator cage 3 to the destination stopping point position, as well as the trip/speed profile 20.1, 20.2 corresponding with this residual distance, can be recalculated and activated.
It is explained in the following on the basis of
In the case of usual plots of the travel speed, such as illustrated in
A further exemplary measure for avoidance of impermissibly large deviations between the instantaneously registered and the actual elevator cage position is explained in the following. The slip between the drive pulley 9 and the support means 5, which is to be anticipated during travel, is calculated into the calculation of a trip/speed profile 20.1, 20.2, 20.6, 20.7, which is described by
The slip, which arises between the drive pulley 9 and the support means 5 during travel of the elevator cage 3, can be strongly dependent on the cage loading by passengers or freight during the journey. A further measure for avoidance of impermissibly large deviations between the instantaneously registered and the actual elevator cage position consists in that the afore-described slip correction is carried out in the manner that the calculated travel distance between the instantaneous elevator cage position and the destination stopping point position or the calculated remaining residual distance to the destination stopping point position is multiplied by a load-dependent slip factor fS/b. Such load-dependent slip factors can be stored in a table memory of the elevator control in association with a respective one of a plurality of cage loading ranges. For carrying out a slip correction as described in the foregoing a load-dependent slip factor fS/b is, on the basis of a measurement of the instantaneously present cage loading, read out of a column, which is associated with the corresponding cage loading range, of the table memory. Information about the respective instantaneously present cage loading is supplied by a load measuring device 11 (
Load-dependent slip factors fS/b correspond with the ratio between the travel distance detected for a specific journey of the elevator cage 3 by the incremental rotary encoder via a coupling liable to slip and the actual travel distance calculated on the basis of the known positions of the stopping point markings 13. In the course of normal operation of the elevator installation they can be ascertained in accordance with a method described in the following. This method is based on the concept of ascertaining, in each of several journeys of the elevator cage with cage loading of similar size, the slip factors which in that case have actually arisen and which are termed actual value slip factors in the following, forming a mean value therefrom and making this mean value available as a load-dependent slip factor fSb, which applies to the respective cage loading range, for calculation of trip/speed profiles. Such an actual value slip factor is possibly ascertained after each trip of the elevator cage 3. For this purpose a first value is registered for the travel distance detected on the basis of the signals of the incremental rotary encoder 12 during travel between the end of the stopping point marking of the start stopping point and the start of the stopping point marking of the destination stopping point. Moreover, a second value for the stated travel distance is calculated by the elevator control from the registered stopping point position values of the start stopping point and the destination stopping point with consideration of the defined length of the stopping point markings. The quotient of the first and second values is then stored as actual value slip factor in association with that cage loading range which can be assigned to the cage loading present in the evaluated travel. The storage can take place dynamically, i.e. a number of successively detected actual value slip factors is stored according to the first in-first out principle in columns of a table memory, wherein each column is associated with one of a plurality of cage loading ranges. For each of the table columns, i.e. for each cage loading range, a mean value of the actual value slip factors stored therein is periodically calculated. These mean values are then available as information for calculation of a trip/speed profile 20 for movement of the elevator cage from an instantaneous position of the elevator cage until reaching a destination stopping point, with a specific cage loading.
The value of the ascertained actual value slip factors can be greater or smaller than 1 depending on the respective combination of cage loading and travel direction. In the case of upward journeys of the elevator cage the actual value slip factor is greater than 1 when the total weight of the elevator cage is greater than the weight of the counterweight, and smaller than 1 when the total weight of the elevator cage is smaller than the weight of the counterweight. In the case of downward journeys the ratios are reversed, i.e. in downward journeys actual value slip factors arise having values corresponding with the reciprocal values of the actual value slip factors resulting in the case of upward journeys with the same weight ratios. If the ascertained actual value slip factors are stored only in association with cage loading ranges and not additionally with travel direction, then the reciprocal values of the ascertained measurement values are to be registered for one of the travel directions. In the case of correction of the remaining residual distances or the corresponding trip/speed profiles, the reciprocal values of the load-dependent slip factors fS/b extracted from the table memory are again to be used for this travel direction. The use of reciprocal values can be avoided if the ascertained actual value slip factors in the case of storage are associated not only with different cage loading ranges, but additionally with the travel directions in which they were ascertained.
In the previous explanations it was assumed that the stopping point position values of all stopping points 7 and thus the position values of the stopping point markings 13 associated therewith are known to the elevator control. However, these data have to be input into the elevator control when the elevator installation is placed in operation. This is possibly carried out in that the elevator control is caused to allow the elevator cage 3 to execute a learning trip which comprises an upward learning trip and a downward learning trip. The learning trip extends over all stopping points 7 and the stopping point markings 13 associated with these stopping points and correctly leveled relative thereto. The upward learning trip of the elevator cage 3 possibly begins from a position lying somewhat below the lowermost stopping point. During the upward learning trip the elevator control 10 continuously detects the instantaneous position of the elevator cage 3 on the basis of the signals of the incremental rotary encoder 12 and in the case of travel of the elevator cage past the stopping point markings 13 the stopping point sensor 15 mounted on the elevator cage 3 detects the starts or the lower edges 14 of these stopping point markings. On detection of the lower edge 14.1 (
In another embodiment of the method the learning trip can additionally serve the purpose of checking or correcting the value of the drive pulley diameter, which is input into the elevator control before placing the elevator installation into operation. This checking or correction takes place in the case of over-travel of a stopping point marking by a comparison of the distance, which is detected on the basis of the signals of the stopping point sensor 15 and the incremental rotary encoder 12, between start and end of the stopping point marking with the precisely known length of the stopping point marking.
As already mentioned, the coupling between the movement of the elevator cage 3 and the incremental rotary encoder 12 detecting this movement is realized by way of the support means 5 and the drive pulley 9. In the case of detection of the instantaneous position of the elevator cage during the upward learning trip and thus in the case of the association, which takes place then, of the stopping point position values with the stopping points 7, deviations therefore arise between the stopping point position values detected on the basis of the signals of the incremental rotary encoder 12 and the actual stopping point position values, which deviations are caused by the slip arising between the support means and the drive pulley.
By way of
Since the weight GGg of the counterweight 4 is greater than the weight GAk of the empty elevator cage, in the case of the upward learning trip of the elevator cage a negative slip between the support means 5 and the drive pulley 9 results. This can mean that the upward travel distance De/auf detected by the incremental rotary encoder 12 is less than the actual travel distance Dt/auf of the elevator cage. In the subsequent downward learning trip of the elevator cage a positive slip results, since the traction force to the transmitted by the drive pulley 9 to the support means 5 acts in the direction of the movement. This has the consequence that the downward travel distance de/ab detected by means of the incremental rotary encoder 12 is greater than the actual downward travel distance dt/ab.
The correction method proposed here is based on the recognition that in the case of a learning trip, which comprises an upward learning trip and a subsequent downward learning trip, with empty or lightly loaded elevator cage a difference results between the upward travel distance de/auf, which is detected from a specific point in the lower elevator region to a reversal position by means of the incremental rotary encoder, and the downward travel distance de/ab detected from the reversal position to the specific point, and that this difference corresponds with the total slip Stot, which is composed of the slip Sauf which has arisen in the upward travel and the slip Sab which has arisen in the downward travel.
These relationships are graphically illustrated in
If the elevator cage 3 in the downward learning trip has now reached the specific point at which in the case of the upward learning trip the measurement of the detected upward travel distance de/auf was commenced with the position value ‘0’, then the position value, which was detected at the specific point, or the counter state of the position detecting system, will have reached a value which lies in the negative region by the sum, which is termed total slip Stot, of the two slip values Sauf and Sab and corresponds with the difference of the detected downward travel distance de/ab and the detected upward travel distance de/auf.
As illustrated in
With the assumption that the slip in the case of upward travel is of the same magnitude as the slip in the downward travel, the learning trip slip factor fS/L can be derived therefrom as follows:
fS/L=learning trip slip factor
dt/auf=actual upward travel distance
dt/ab=actual downward travel distance
de/auf=detected upward travel distance
de/ab=detected downward travel distance
Sauf=slip in upward travel
Sab=slip in downward travel
Stot=total slip
It is thus possible to determine the stopping point position values of the stopping points 7 with great accuracy by means of a learning trip although the rotary encoder, which detects the movement of the elevator cage, is coupled with the movement of the elevator cage by way of a connection, namely via the drive pulley and the support means, subject to slip.
A semiconductor table memory of the elevator control is illustrated by the reference numeral 200, in which the stopping point position values associated during the learning trip with each stopping point and corrected by the learning trip slip factor fS/L are stored so as to be able to be called up.
A semiconductor table memory of the elevator control is illustrated by the reference numeral 201, the memory comprising several table columns which are each associated with a respective cage loading range and a travel direction and in which the actual value slip factors, which are ascertained in normal operation and dependent on the cage loading and the travel direction, are dynamically stored, i.e. according to the first in-first out principle.
A semiconductor table memory of the elevator control is illustrated by the reference numeral 202, which comprises several table columns which are each associated with a respective cage loading range and a travel direction and in which the load-dependent slip factors fS/b calculated in step 130 and dependent on the cage loading in the travel direction are stored and able to be called up for correction of the calculated actual travel distance as described in step 113.
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. We therefore claim as our invention all that comes within the scope and spirit of these claims.
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