WO2016091919A1

WO2016091919A1 - Method for determining a load in a car of an elevator system

Info

Publication number: WO2016091919A1
Application number: PCT/EP2015/079053
Authority: WO
Inventors: Ingo Pletschen; Stephan Rohr
Original assignee: Thyssenkrupp Elevator Ag; Thyssenkrupp Ag
Priority date: 2014-12-11
Filing date: 2015-12-09
Publication date: 2016-06-16
Also published as: DE102014225551A1

Abstract

The invention relates to a method for determining a load in a car (102) of an elevator system (100), wherein a position of the car (102) in an elevator shaft (101) is determined using an absolute value encoder (120), a relative movement of the car (102) as a result of a change in the load is determined using the absolute value encoder (120), and the load in the car is determined from the determined position of the car, the determined relative movement, and the spring constant of the elevator system (100).

Description

Method for determining a load in a car of an elevator system

description

The present invention relates to a method for determining a load in a car of an elevator system, wherein a car position of the car in an elevator shaft is determined by means of an absolute value encoder.

State of the art

In an elevator system, a cabin can be moved by means of a suitable drive in an elevator shaft. For the operation of the elevator system usually a load or a load changes in the cabin must be able to be determined. For example, in the course of a stop in a stopping floor, a load change takes place in the cabin, for example because passengers enter or leave the cabin. During the stop, usually the service brake is activated and disabled the drive of the cabin. At the end of the stop, the drive is reactivated and the service brake released.

In order to prevent a "jumping" or "jerking" of the cabin after a load change when releasing the service brake and the cabin unintentionally makes a set up or down, a drive torque must be precisely provided ("smooth start"). This drive torque depends on the current load in the cabin. In order to determine the load change or the load in the cabin, load measuring sensors are usually used.

The cabin can be stored within a chassis or a frame by means of cabin springs. Such cabin springs are arranged between the cab and the chassis. For example, as the load in the cabin changes, as passengers enter or leave the cabin, the cabin makes a relative movement relative to the chassis. This relative movement corresponds to a travel or compression of the cabin springs.

This spring travel or this relative movement of the cabin can be used to determine the load in the cabin. By means of the load measuring sensor, the relative movement of the cabin The load in the cabin can be determined using the spring constants of the cabin springs. For example, this load measuring sensor may comprise a distance measuring sensor which is arranged in the chassis. However, such load measuring sensors usually have to be calibrated manually by employees. First of all, the employees must determine the spring constant of the cabin springs and enter them into the load measuring sensor. However, the spring constant of the cabin springs may change over time, for example due to wear and tear. Therefore, it is necessary at regular time intervals to manually calibrate the load measuring sensor again. As part of this, the elevator system must be taken out of service and the spring constant of the cabin springs must be determined again by an employee.

Such a determination of the load of the cabin is therefore associated with a very great effort, in particular with high cost and frequent recalibration. In addition, the load measuring sensor is associated with material costs.

It is therefore desirable to provide an improved way of determining a load of a car of an elevator system. Disclosure of the invention

This object is solved by the subject matters of the independent claims. Advantageous embodiments are the subject of the dependent claims and the following description.

An elevator system with a cabin that can be moved in a lift shaft via a cable drive physically comprises a spring system consisting of individual spring elements. This spring system has an overall spring constant, which is composed of individual spring constants of the individual spring elements.

Such individual spring elements may be formed, for example, as the said cabin springs. The cabin can be stored within a chassis or a frame or car by means of these cabin springs. Such cabin springs are arranged between the cab and the chassis. Furthermore, a suspension cable to which the cabin is suspended also constitutes a spring element due to its elasticity. A suspension cable spring constant of this suspension cable depends on its free length and thus on the cabin position of the car in the elevator shaft. Further spring elements may be formed, for example, by a sprung suspension cable suspension.

According to the invention, a load in the cab of the elevator system is determined by first determining a car position of the car in the hoistway by means of an absolute encoder. A relative movement of the car due to a load change is also determined by means of the absolute encoder. From the determined car position, the determined relative movement and a spring constant of the elevator system, the load in the car is determined.

By means of the absolute encoder, the car position x _K , ie the current position of the car in the elevator shaft is determined. This cabin position x _K corresponds in particular to a so-called cable position of a carrying cable on which the cabin is suspended. This cable position corresponds in particular to the position in the elevator shaft at which one end of a carrying cable is connected to the car. In particular, the cabin position x _{K is determined} directly or shortly before a load change m in the cabin.

Furthermore, the relative movement x _{K of} the car, ie a change in the car position, is determined by means of the absolute encoder. In the case of a load change m in the cabin, for example when passengers leave or enter the car, the car makes such a relative movement x _K relative to a fixed reference point in the elevator system, for example relative to the elevator shaft. This relative movement x _K corresponds in particular to a spring travel or spring deflection of a spring system of the elevator system.

From the determined cabin position x _K , the determined relative movement x _K and the spring constant C _{ges of} the elevator system, the load in the cabin is determined. This spring constant C _tot is in particular the total spring constant of the entire spring system, which is composed of individual spring constants of the individual spring elements.

In particular, in the case of a series connection of the corresponding spring elements, this total spring constant is composed as follows: 1 1 1

ges c, c s, eil

Cseii is a suspension rope spring constant of the suspension rope and is composed as follows:

C s, hurry

X K,

A _s is the cross-sectional area of the supporting cable and E _{s is} the modulus of elasticity of the supporting cable. The suspension rope spring constant depends on the free suspension rope length and thus on the cabin position x _K or the cable position: C _Se = C _Se ii (xK)

Ci is a cabin spring constant of spring elements mounted on the cab. This cabin spring constant is composed in particular of spring constants of the spring element of the suspension cable suspension and spring constants of the cabin springs. The cabin spring constant is in particular independent of the cabin position. The total spring constant Ctotal, however, is dependent for C _Se of the car position x _K: C _tot = C _tot (x _K) For a known cage position-dependent total spring constant C _ges and the current car position x _K and the determined relative movement x _K of the cabin, the Load change m in the cabin can be determined:

AF = Am - g = Ax _K ^■ C tot

Am = - Ax C tot

G

From the load change m, the load in the cabin can be determined in each case. Advantages of the invention

According to the invention, the load in the cabin is determined not by means of a load measuring sensor, but by means of the absolute value transmitter of the elevator system. Lift systems usually have such an absolute value transmitter in order to determine the car position in the elevator shaft. By way of example, such an absolute value encoder can have a measuring tape and a measuring unit. Such a measuring tape, for example a magnetic tape, can be arranged in the elevator shaft, the measuring unit can be arranged on the cabin itself or on a chassis or frame of the cabin. No additional components are needed for the invention. The already existing in a conventional elevator system components can be used for the invention. In addition, components, such as the load measuring sensor, and the associated maintenance costs can be saved.

The total spring constant C _ges can either be known, for example from a manufacturing process of the elevator system, or can also be determined or learned according to a preferred embodiment of the invention.

According to this preferred embodiment, the spring constant of the elevator system is determined in the course of a calibration phase of the elevator system. Further preferably, the spring constant is estimated or learned in the course of the calibration phase by means of statistical methods. This calibration phase can be carried out in particular in the course of a (re) commissioning of the elevator system or before a (first) regular drive of the car. The spring constant learned during this calibration phase can be used during normal operation of the elevator system to determine the load.

In particular, the spring constant is determined automatically, for example by an elevator control. In particular, it is not necessary in the course of the calibration phase for an employee to carry out manual measurements in the elevator system. All measurements required for the determination of the spring constants can be carried out autonomously by the elevator system or by the elevator control. This determination of the spring constant is straightforward and requires little effort.

Advantageously, at least two reference measurements are carried out in the course of the calibration phase. These at least two reference measurements are preferably carried out in each case with a known load or in each case with a known load change. In the course of the at least two reference measurements, respectively the cabin position by means of the absolute encoder, the relative movement due to a known load change by means of the absolute encoder and a cross flow i _q or a proportional to the transverse flow variable, such as the drive or motor torque (see below), a drive of the elevator system.

The drive of the elevator system is designed in particular as a synchronous machine, more particularly as a permanent magnet synchronous machine (PSM). The drive can also as Be formed asynchronous machine. In particular, the drive is designed as a field-oriented controlled induction machine. Such a field-oriented control is described by two characteristic currents, the longitudinal current i _d and the transverse current i _q . The longitudinal current i _d can be interpreted as a field-forming current, the cross-flow i _d as a moment-forming current. The longitudinal flow i _d of such a rotating field machine is set in particular to zero.

The transverse flow i _q is in particular proportional to the output by the drive Antriebsbzw. Engine torque M:

M i _q

In order to determine the drive or motor torque, thus no complex torque sensor is necessary. The drive or motor torque can be determined by means of simple and inexpensive current sensors. By means of such current sensors, phase currents of the drive are detected, from which the transverse current i _q can be determined by a coordinate transformation.

The at least two reference measurements can be carried out, for example, each in the course of a stop of the car stop. The cabin is in the course of such Haltestopps each in a holding floor. In this case, the reference measurements can be carried out in each case in the same holding floor, that is to say in the case of at least substantially identical cabin positions, or in different holding floors, that is, in different cabin positions. In the course of the reference measurements, it is also possible in each case to drive the cabin between two storeys. In the course of these reference measurements, a first cross-flow of the drive and the cabin position x _K (directly) are determined in each case before a load change m in the cabin. Then the car is loaded in each case with the known load. Thus, the load change m results in the cabin. After this load change m, a second transverse current of the drive and the relative movement x _{K are determined} on the basis of the load change. From this first and second cross-flow, a change of the cross current i _{q is determined} on the basis of the load change m.

In particular, such a change of the cross current i _q by what value the cross current i _q must be changed due to the drive control, so that the cabin after the Load change m when approaching does not unintentionally make a set up or down ("smooth start").

In the course of the reference measurements, a value triplet (x _K , Χκ, i _q ) from cabin position x _Kj relative movement x _K due to a load change m and change of the cross _current i _q due to the load change m is determined in particular. In particular, at least two such value triplets (x _K , Χκ, i _q ) are determined in the course of the calibration phase. From these at least two value _triplets (x _Kj x _K , i _q ), the spring constant of the spring system can be determined as follows.

The change of the cross current i _q is proportional to the load change m, further proportional to the corresponding force change F and further proportional to the relative movement of the cabin x _K :

AF AL Am Ax _r

As explained above, the total spring constant C _{ges is} composed of the suspension cable spring constant Cs _e and the cabin spring constant Ci as follows:

Cges E _S A _S

Between total spring constant C _gesj load change m, change of the cross flow i _qj relative movement of the cabin x _K and cabin position x _K thus have the following relationships:

Am - g

Ax

Relative movement of the car x _K is thus a linear function of the car position From the at least two triples (x _Kj _Kj i x _q) of the reference measurements, the total spring constant C can be determined on the basis of these relationships _ges. The at least two value triples (x _K , x _K , i _q ) each give a point in a diagram of the relative movement of the cabin x _K plotted against the car position x _K. These points can be used to lay a straight line or equalization line. A slope of this line can be as or as

C.,

Thus, from the value triplets, the cabin spring constant Ci and the suspension cable spring constant Cse can be determined. From these, the total spring constant C _{ges of} the elevator system can be determined.

In particular, at least three reference measurements are carried out in the course of the calibration phase. A first reference measurement is performed with an empty cabin without load, m ^ Okg. A second and third reference measurement are each performed with different known non-zero loads m ₂ and m ₃ in the cabin.

Advantageously, the spring constant C _{ges is determined} from the cabin positions x _K , relative movements x _K and transverse currents i _q determined in the at least two reference measurements by means of an error minimization method, in particular by means of a method of least squares (least-square method). In particular, the cabin spring constant Ci and the caster spring constant C may be determined from the straight line by means of such an error minimization method.

As can be seen from the relationships explained above, there is a linear first relationship between the lateral flow i _q and the load m of the car. Furthermore, there is a linear second relationship between the change of the transverse current i _q and the relative movement of the cabin x _K. This first and / or second context is preferably determined in the course of the calibration phase. For this purpose, in particular the values for the cabin position x _K determined in the course of the reference measurements, the load m the cabin, the transverse flow i _q , the relative movement x _K , the load change m and the change of the cross-flow i _q tabular stored. Preferably, the spring constant Cges is determined from this first and / or second context, in particular by means of the error minimization method or by means of the least squares method.

According to a preferred embodiment of the invention, the load in the cabin is determined during regular operation of the elevator system during a stop of the car. In particular, a stop is understood to mean that, during regular operation of the elevator system, the cabin enters a holding floor and performs an operational stop there. If a load change takes place during the stop, this is determined and from this the load in the cabin is calculated.

Thus, the load in the cabin at the end of the stop is known, ie before the car leaves the holding floor again. At the end of the stop, the drive of the car is in particular deactivated and a holding brake is activated. In order to set the cabin in motion, a drive or motor torque is provided depending on the current load in the cabin. If the holding brake is released, it does not come to a "jumping" of the cabin or a noticeable, jerky movement of the cabin.

Advantageously, a precontrol value is determined for a control of the drive of the elevator system. By means of this pre-control value, at the end of the stop-stop, the drive or engine torque can be provided as a function of the current load in the cabin as described above. In particular, a pilot control value for the cross current i _{q of} the drive is determined.

Such a precontrol value can be determined in particular by means of the first relationship and / or by means of the second relationship. In particular, from the determined relative movement of the cabin x _K due to the load change m by means of the second relationship between the change of the lateral flow i _q and the relative movement of the cabin x _K, a corresponding value for the change of the transverse flow i _{q is determined} for the corresponding load change m. This change of the cross _current i _q is in particular added to a last determined _{precontrol value} \ _{ν0Γ: 0} , which was determined in the course of the last stop of the stop, in order to reduce the precontrol value i _q! To determine _before the current stop: q, before q, before, 0 q

Alternatively or additionally, the precontrol value can also be determined by means of an error minimization method, in particular by means of a method of least squares. For a detailed explanation of the determination of such a pilot value by means of the error minimization method, reference is made to EP 2 522 612 AI.

EP 2 522 612 A1 describes a method for setting a control loop for a drive of an elevator installation, in particular for an electric motor drive. The control loop has a drive control loop and a pilot control, which predefines a feedforward setpoint for the drive control loop. The pre-control target value is a function of at least one measurable variable of the elevator installation and of at least one adjustable pre-control parameter. The pre-control parameter is automatically set upon start-up of the elevator installation and / or during operation of the elevator installation by means of an error minimization method which minimizes an error between the pre-control setpoint and a drive setpoint applied by the pre-control setpoint occurring during a start-up run and / or during a drive run.

For a detailed description of the theoretical fundamentals of such feedforward control and of such pilot desired values, reference should be made in particular to paragraphs [0031] to [0062] of EP 2 522 612 A1. For a specific embodiment of such feedforward control and the corresponding error minimization method, reference is made in particular to paragraphs [0065] to [0117] of EP 2 522 612 A1. In paragraphs [0065] to [0071], first a specific example of an elevator installation is described therein, in paragraphs [0072] to [0090] a special regulation of this elevator installation is explained, in paragraphs [0091] to [0103] Specifically, the corresponding feedforward control is described and in paragraphs [0091] to [0117] the corresponding error minimization method is dealt with.

In particular, the precontrol value according to this preferred embodiment of the invention can be determined by means of the error minimization method analogously to the pilot desired values described in EP 2 522 612 A1. In contrast to the EP 2 522 612 AI, however, according to this preferred embodiment of the invention no load measuring sensor or no Load measuring device used to determine the load in the cabin or the loading of the car or a car. Instead, the load in the cabin is determined according to a preferred embodiment of the method according to the invention. According to an alternative or additional preferred embodiment of the invention, the load in the cabin during normal operation of the elevator system is determined during a trip of the car. For this purpose, the cross-flow of the drive is determined while driving. The load in the cabin is determined in particular from this cross-flow and the first connection. In particular, the load is estimated or determined by statistical methods. In particular, the load can be determined by means of one of the error minimization methods or by means of the least squares method.

This determination of the load by means of the lateral flow i _q during the travel of the car can be carried out in addition to the determination of the load from the determined car position, the determined relative movement and the spring constant of the elevator system. Furthermore, this determination of the load while driving may be performed in addition to the determination of the load in the car during the stop of stopping.

By determining the load during the drive of the cabin, any errors or an error propagation of the determination by means of the cabin position, relative movement and spring constants can be corrected. In particular, this corrects errors or error propagation of the determination of the spring constants.

In particular, the load determined during the stopping stop and the load determined during the journey can be compared with one another and checked for consistency. In particular, if these two distinct loads differ, this indicates that an incorrect overall spring rate is used, for example, because the actual overall spring rate has changed due to wear. If these two specific loads deviate from one another, in particular a corresponding corrective measure can be carried out, for example, the total spring constant can be redetermined by means of reference measurements.

Preferably, the spring constant of the elevator system is determined in the regular operation of the elevator system. This determination of the spring constant takes place in particular in addition to the determination in the course of the calibration phase. The spring constant can thus in regular operation of the elevator system can be corrected or recalibrated. In particular, the spring constant is determined during a drive of the cabin. For this purpose, the transverse flow is determined while driving and the spring constant is determined from this particular cross-flow and from the first context and / or from the second context. The determination of the spring constant C _ges from this first and / or second context can be carried out analogously to the calibration phase, in particular by means of the error minimization method or by means of the least squares method. In this way, changes in the spring constant over time, for example due to wear of the individual spring elements, are automatically compensated. Thus, an automatic recalibration can be easily performed during regular operation. For such recalibration, it is not necessary to take the elevator system out of service. Furthermore, no manual intervention of employees is necessary.

This automatic recalibration can be performed, for example, at fixed intervals, for example at fixed time intervals, after a certain number of car trips or after a fixed number of operating hours of the elevator system. For example, the automatic recalibration can be carried out after every 20th drive of the car.

The invention further relates to an elevator system with a movable in a hoistway cabin. Embodiments of this elevator system according to the invention will become apparent from the above description of the method according to the invention in an analogous manner. The elevator system according to the invention comprises a control unit, for example an elevator control, which, in particular in terms of programming, is set up to carry out a preferred embodiment of the method according to the invention. The implementation of the method in the form of software is also advantageous, since this causes particularly low costs, in particular if an executing control unit is still used for further tasks and therefore exists anyway. Suitable data carriers for providing the computer program are, in particular, floppy disks, hard disks, flash memories, EEPROMs, CD-ROMs, DVDs and the like .m. It is also possible to download a program via computer networks (Internet, intranet, etc.). It is understood that the features mentioned above and those yet to be explained below can be used not only in the particular combination given, but also in other combinations or in isolation, without departing from the scope of the present invention.

The invention and its advantages are illustrated schematically with reference to an embodiment in the drawing and will be described in detail below with reference to the drawing.

figure description

Figure 1 shows schematically a preferred embodiment of an inventive

Elevator system.

Figure 2 shows schematically a preferred embodiment of an inventive

Process as a block diagram.

1 shows a preferred embodiment of an elevator system according to the invention is shown schematically and designated 100. The elevator system 100 comprises a car 102 which can be moved in an elevator shaft 101.

The cab 102 is mounted in a chassis 103. On the chassis 103, a support cable 104 is attached. This support cable 104 is connected via a traction sheave 105 and a deflection roller 106 with a counterweight 107.

The elevator system 100 comprises a drive 110, which in this example is designed as a traction sheave drive. This traction sheave drive 110 comprises the traction sheave 105 and an electric machine 109. The traction sheave 105 is connected to the electric machine 109 via a shaft 108. The electric machine 109 is formed in this example as a synchronous machine, in particular as a permanent-magnet synchronous machine (PSM).

The cab 102 is supported in the chassis 103 by means of cabin springs 111. The support member 104 is disposed on the chassis 103 on a sprung suspension cable suspension 112. The cab springs 111 and the suspension suspension suspension 112 each have an individual spring rate. A cabin spring constant Ci is a cabin spring constant of spring elements disposed on the cab. This cabin spring constant is composed of these spring constants of the cabin springs 111 and the sprung suspension cable suspension 112.

Furthermore, the support cable 104 is also a spring element with a suspension cable spring constant C. A total spring constant C _{tot of} the elevator system 100 is composed of a series connection of this suspension cable spring constant C and the cabin spring constant Ci. The suspension cable spring constant C is dependent on the free length of the support cable 104 and thus on the car position of the car 102 relative to the elevator shaft 101. Accordingly, the total spring constant C _{tot is} dependent on the car position. The elevator system 100 further includes an absolute encoder 120 for determining a car position of the car 102 relative to the hoistway 101. The absolute value encoder 120 comprises a measuring tape 122 in the form of a magnetic tape and a measuring unit 121. The measuring tape 122 is arranged in the elevator shaft, the measuring unit 121 on the cabin 102.

According to the invention, the elevator system 100 does not include a load sensing sensor to determine a load in the cab 102. Instead, the elevator system 100 is configured to perform a preferred embodiment of a method of the invention to determine a load in the cab 102.

In particular, the elevator system 100 comprises a control unit 130, for example an elevator control. This control unit 130 is, in particular programmatically, configured to perform this preferred embodiment of the method according to the invention, which is shown schematically in Figure 2 as a block diagram.

In the course of a commissioning of the elevator system 100, first of all a calibration phase 210 of the elevator system 100 is performed. During this calibration phase 210, the car-position-dependent total spring constant C is determined _ges of the elevator system 100th During the calibration phase, two reference measurements are performed. In the course of a first reference measurement 211, the cabin 102 is loaded with a first known load, for example 80 kg. This results in a first load change of rru = 80 kg in the cabin 102.

Immediately before this first load change rr, a first car position x _{kl of} the car 102 in the hoistway 101 is determined by means of the absolute value transmitter 120. Furthermore, a first transverse flow is determined, with which the synchronous machine 109 is energized, so that the car can hold x _kl when starting the current first cabin position.

After the first load change rru, the car position in the hoistway 101 is determined again by means of the absolute value transmitter 120. Thus, a first relative movement x _{K1 is determined} on the basis of the first load change rr. Furthermore, a second cross-flow is determined, with which the synchronous machine 109 is energized so that the car can hold the current cabin position. From the first and the second transverse flow, a first change of the transverse current i _q i is determined on the basis of the first load change rru. In the course of the first reference _measurements 211, a first value triplet (x _K1 , x _K1 , i _q1 ) is thus determined.

In the course of a second reference measurement 212, the cabin 102 is loaded with a second known load, for example 100 kg. The first load is removed from the cabin 102. This results in a second load change of m ₂ = 20 kg in the cabin 102.

Immediately before this second load change rru, a second car position x _{kl of} the car 102 in the hoistway 101 is determined by means of the absolute value transmitter 120. Furthermore, a first cross flow is determined again. After the second load change m ₂ , the car position and a second relative movement x _K2 are again determined by means of the absolute value transmitter 120 on the basis of the second load change m ₂ . Furthermore, a second transverse flow and a second change of the transverse flow i _q2 due to the second load change m _{2 are again} determined. In the course of the second reference _measurements 212, a second value triplet (x _K2 , x _K2 , i _q2 ) is thus obtained.

In a step 213, the total spring constant C _{ges of} the elevator system 100 is determined from the two value tetrals (x _K i, X _K i, i _q i) and (X _K2 , X _K 2 _> i _q2 ). The two Wertetnpple be plotted on a graph of the relative movement of the cabin x _K registered against the car position x _K. A balance line is laid through the points.

The slope of this G determines who

Ordinate intersection as

Thus, the cabin spring constant Ci and the suspension cable spring constant Cse are determined from the two value triplets. From these, the cabin position dependent total spring constant C is calculated _ges of the elevator system 100th In particular, the determination of the cabin spring constant Ci and the suspension cable spring constant C _Se ii is carried out by means of an error minimization method, in particular by means of a least-squares method. The cabin position dependent total spring constant Cges of the elevator system 100 determined during the calibration phase 210 may be used in the regular operation 220 of the elevator system 100 to determine the load in the cabin. In particular, the load in regular operation 220 is determined in the course of stopping the car 102. In step 221, the cab retracts into a holding floor during regular stop in the course of a stop. A current car position x _K - ₂₂ i is determined by means of the absolute encoder 120.

After this determination, a load change m ₂₂ i occurs in the cabin 102 in step 222, for example because persons leave and / or enter the cabin 102.

After this load change m ₂₂ i, a relative movement x _K _ _{221 of} the cabin 102 relative to the elevator shaft 101 is determined in step 223 by means of the absolute encoder 120. In step 224, this cabin position becomes x _K. ₂₂ i and the cabin position-dependent total spring constant C _ges determined in the course of calibration phase 210 Spring constant C _ges x _K _ _22l ) at the cabin position x _K. ₂₂ i determined, indicated by reference numeral 225.

In step 226, the cabin position χ _κ . ₂₂ ι, the relative movement x _K. ₂₂ i and the total spring constant C _ges x _K _ _22l ) at the cabin position x _K. ₂₂ i determines the load change m ₂₂ i, in particular by means of the relationship:

^ ^M ⁼ 221 Χχ-221 ^'C _ges ^{X K-22L)

&

From the load change m ₂₂₁ , the load in the car 102 and a pre-control value i _{q! Before} for the cross flow i _q intended for smooth starting.

LIST OF REFERENCE NUMBERS

100 elevator system

101 elevator shaft

102 cabin

103 chassis, frame

104 carrying rope

105 traction sheave

106 pulley

107 counterweight

108 wave

109 electric machine, synchronous machine

110 drive, traction sheave drive

111 cabin springs

112 suspension rope suspension

120 absolute encoders

121 measuring unit

122 magnetic tape, measuring tape

130 control unit

210 Calibration phase of the elevator system

211 to 213 process steps

220 regular operation of the elevator system

221 to 226 process steps

Claims

claims

A method of determining a load in a car (102) of an elevator system (100), wherein

a cabin position of the car (102) in an elevator shaft (101) is determined (221) by means of an absolute value transmitter (120),

a relative movement of the car (102) due to a load change by means of the absolute encoder (120) is determined (223) and

from the determined car position, the determined relative movement and a spring rate of the elevator system (100) the load in the car is determined (226).

2. The method of claim 1, wherein the spring constant of the elevator system (100) in the course of a calibration phase (210) of the elevator system (100) is determined.

3. The method according to claim 2, wherein in the course of the calibration phase (210) of the

Elevator system at least two reference measurements (211, 212) are each performed with a known load change in the cabin (102) and wherein in the course of at least two reference measurements each of the cabin position by means of the absolute encoder (120), the relative movement due to the load change by means of the absolute encoder (120 ) and a cross flow or a proportional to the cross - flow size of a drive (110) of the

Elevator system (100) can be determined.

4. The method of claim 3, wherein the spring constant of the elevator system (100) based on the at least two reference measurements (211, 212) by means of a

Error minimization method, in particular by means of a method of the smallest

Error squares is determined (213).

5. The method according to claim 3 or 4, wherein a first relationship between

Cross-flow and load and / or a second relationship between a change in the cross-flow and the relative movement of the cabin (102) are determined due to the load change.

6. The method of claim 5, wherein the spring constant of the elevator system (100) is determined from the first context and / or from the second context.

A method according to any one of the preceding claims, wherein the load in the car (102) is determined in a regular operation (220) of the elevator system during a stop of the car (102).

8. The method according to any one of the preceding claims, wherein a pilot value for driving the drive (110) of the elevator system (100) is determined.

A method as claimed in any one of the preceding claims, wherein the load in the cab (102) during regular operation (220) of the elevator system (100) is determined during a trip of the cab.

10. The method according to any one of the preceding claims, wherein the spring constant of the elevator system (100) in the regular operation (220) of the elevator system (100) is determined.

11. A control unit (130) which is adapted to perform a method according to any one of the preceding claims.

12. elevator system (100) with a in a hoistway (101) movable cabin (102) and with a control unit (130) according to claim 11.

A computer program that causes a control unit to perform a method according to any one of claims 1 to 10 when executed on the control unit (130).

14. Machine-readable storage medium with a stored on it

Computer program according to claim 13.