EP3848314B1 - System for measuring load in an elevator system and method for determining the load of an elevator car - Google Patents

Description

The present invention relates to a system for measuring the load in an elevator system with an elevator car, a power supply system and a prime mover, and to a method for determining the load of the elevator car. Elevator systems for transporting people and goods are well known and widespread. An elevator system typically includes an elevator car that is moved vertically along an elevator shaft by a prime mover. In the simplest case, the drive machine performs mechanical work to transport passengers or goods to a higher position, or brakes the elevator car when lowering from a higher to a lower location. In many cases, such an elevator system is additionally equipped with a counterweight in order, among other things, to minimize the transport energy required for a statistically frequently occurring load on the elevator car, e.g. half load. If such a counterweight is present, then it is possible that mechanical work is required from the drive machine when an empty elevator car is lowered and energy is released when an empty elevator car is raised.

Since elevator systems designed to transport people must meet high safety requirements, they are subject to extensive and frequent maintenance. In order to be able to estimate the wear of individual components without a complex inspection, it is advantageous to have meaningful data on previous operation available. In particular, the number of trips and the load transported are important parameters. One possibility of measuring the mentioned load using sensors attached to the elevator car is presented in EP 0 755 894 A1 described. Another possibility for determining the transported load in an industrial pendulum system based on the power applied by the drive machine is presented in US 4,053,742 described.

Both inventions mentioned have in common that the measurement of the values on their basis The load is subsequently calculated using permanently installed sensors, the presence of which had to be planned for in the design of the systems. This requirement can reduce flexibility. A change or retrofitting is often only possible with considerable effort and is particularly difficult if the functionality of relevant parts of the elevator system, such as the elevator control, is not precisely known. It is also desirable to increase redundancy and thus reliability.

Another system for determining the load of an elevator by means of a control according to the preamble of claim 1 is out US 2015274485 A1 known.

It is the object of the invention to improve at least some of the points mentioned above. This object is achieved by the system for measuring the load in an elevator system described in claim 1 and by the method mentioned in claim 9. Further advantageous embodiments are described in the subclaims.

One aspect of the improved system for measuring load in an elevator system relates to an elevator system having an elevator car (e.g., a passenger elevator with a passenger car), a power supply system, and a prime mover. The drive machine is set up to move the elevator car along a shaft and is connected to a power supply system via electrical conductors. The energy supply system is connected to a network connection via electrical conductors. Preferably, the mains connection supplies the energy supply system with a substantially constant nominal voltage and frequency. The system includes a first sensor system for measuring a performance parameter. The performance parameter is indicative of the performance of the drive machine. Furthermore, the system includes a second sensor system for measuring a movement direction parameter of the elevator car. The movement direction parameter is indicative of the direction of movement of the elevator car. Furthermore, the system includes a logic unit that is set up to calculate the load of the elevator car from the measured performance and direction of movement parameters. Furthermore, the elevator system has an elevator control, and the logic unit (150) forms a unit that is functionally separate from the elevator control and does not record any operating status information from the elevator control.

Another aspect of the invention relates to a method for determining the load of the elevator car of an elevator system. The method includes measuring a performance parameter of the electrical conductors using the first sensor system and measuring a movement direction parameter of the drive machine using the second sensor system. The performance parameter becomes the performance of the drive machine determined and the direction of movement of the elevator car is determined from the movement direction parameter. The load of the elevator car is ultimately determined from the power of the drive machine and the direction of movement of the elevator car.

Embodiments of the present invention advantageously make it possible to provide the elements necessary for determining the aforementioned operating data without necessarily having to access a central control of the elevator system. Therefore, flexibility, redundancy and reliability can be increased. According to embodiments, these elements can also be subsequently integrated into an existing elevator system without having to make changes to the existing control and drive electronics. This increases compatibility with existing systems, simplifies application and, among other things, enables flexible and cost-effective retrofitting of existing elevator systems. If the existing elevator system already contains a possibility for determining the moving load, the system according to the invention also provides an additional measurement, through which the existing system can be designed to be redundant and therefore fail-safe and, in the event of discrepancies between the two measurement results, contributes to the detection of a fault.

Since the mechanical power of the drive machine does not necessarily correspond to the load of the elevator car due to the counterweights described above, which are often present, the present invention also solves the problem of relating the direction of movement of the elevator car to the work of the machine and thus determining whether a full or an empty cabin was moved. This increases the informative value of the specific operating data.

In the exemplary embodiments of the invention described here, the determination of a load of the elevator car is provided by means of a combination of sensor systems and a logic unit. The parts of the invention mentioned are typically not integrated into the control or drive electronics or into the mechanical components of the elevator system during production, but are added subsequently, for example during maintenance of the elevator system.

The invention is at least partially functionally separated from the elevator system, so it is not necessary to integrate the sensor systems or the logic unit into the existing elevator system to be integrated in such a way that precise knowledge of how the system works, e.g. the elevator control, is necessary. Likewise, the design according to the invention does not influence the elevator system to any significant extent. Intervention in the existing electromechanical system is thus avoided.

In one exemplary embodiment, the load of the elevator car determined by the invention is provided by a logic unit in the form of a data record. A data set contains at least one transported load as a single data point. In addition, other data can be related to the load, such as the time at which the trip took place, the direction of the trip, the distance traveled, the capacity utilization at a certain time of day and/or a discrepancy between loads when rising and rising Shutting down the elevator system, whereby these examples only serve for description and numerous other combinations are possible and other values that are not measured or calculated by the system described can also be part of such a data set. The logic unit can calculate the performance of the drive machine based on a performance parameter and calculate the direction of movement of the elevator car based on a movement direction parameter. Other values that are calculated on the basis of the determined parameters, such as the torque of the drive machine, the integral of the torque of the drive machine over time, the integral of the electrical power over time, the direction of movement as a derivative of the position, the direction of movement as a derivative the acceleration, the direction of movement as a derivative of the distance, the direction of movement in the form of a binary polarity (e.g. + or -), the load, the load depending on the direction of movement, the integral of the load over time, the sum of all loads in one or multiple intervals, can optionally be calculated by the logic unit and be part of the data set or linked to the data set.

The load can be evaluated in the form of the actual mass, but the load can also be expressed, for example, as the number of people transported, as a percentage of the maximum load or as the electrical or mechanical work expended. In addition to the described values derived from the raw data, the raw data provided by the sensor systems can also be present in such a data record. The data record is temporarily stored by the logic unit and made available to an authorized person upon request. The logic unit can also store the data record on a data carrier save. The data carrier can be exchangeable and suitable for further transport of the data. It is also conceivable that the logic unit actively sends the data record via suitable media when a previously defined condition occurs. The condition can be, for example, the expiration of a previously defined time interval, or the fulfillment of any linked requirements, such as exceeding a previously defined number of trips with a certain minimum load. Any system suitable for sending data sets, such as bus systems, wireless RF systems or packet-based networks, can be considered as a suitable medium. The data set can be cached, redistributed or processed in a decentralized IT infrastructure system, e.g. a cloud. The IT infrastructure system may include a dedicated maintenance and monitoring system.

According to exemplary embodiments, the logic unit can be a dedicated subsystem which, together with the necessary sensors, performs the function according to the invention in relation to an individual elevator system. It is possible for the logic unit to form a unit with one or more sensors of the sensor systems. However, it is also possible for the logic unit to be spatially separated from the respective elevator systems. The logic unit can consist of several subsystems that perform different functions. If the logic unit consists of several subsystems, it is also possible that individual subsystems can carry out one or more functions equally and thus contribute to the reliability of the system. It is possible for a single logic unit to evaluate the sensor data from multiple elevator systems. It is possible for the logic unit to be designed as a central server, which evaluates the sensor data from numerous elevator systems and provides a large number of data sets. The logic unit communicates with the sensor systems via suitable systems, such as analog or digital, wired systems, bus systems, wireless RF systems or packet-based networks.

The logic unit can include an analog/digital converter that digitizes an analog input value, which can be a characteristic of a sensor system. The logic unit may include a memory in which a program for calculating the load of the elevator car is stored. The memory can also contain other information, such as parameters or calibration values that are related to information correlate via the specific elevator system so that they are available to the program. The information mentioned can be saved during the production of the logic unit or later. The information may be information obtained as part of a calibration of the system. The calibration can be carried out, for example, using the values obtained through one or more calibration or learning runs.

To determine the load of the elevator car, the logic unit can make calculations. For this purpose, the logic unit typically comprises at least one controller which is connected to the memory in such a way that it can execute the program stored thereon.

The parameters are provided to the logic unit by the respective sensor systems and can be temporarily stored therein. The program is executed in the controller and performs further operations with the buffered, sensor-determined values, which deliver results based on the input values. To do this, the program can access the part of the memory that contains the elevator system-specific parameters. For example, the elevator system-specific parameter can be a calibration value with which a measured value can be multiplied, for example to calculate the power of the drive machine from the performance parameter or the direction of movement of the elevator car from the movement direction parameter.

To calculate the load, a first sensor system is provided, which provides a parameter based on the electrical power of the drive machine during operation, which is indicative of the mechanical power of the drive machine. In a particularly favorable embodiment, such a parameter can be obtained by determining one or more parameters of one or more electrical conductors that connect the drive machine to the energy supply system. The power supply system can be a frequency converter, as used for the operation of synchronous motors and asynchronous motors. It can also be a rectifier or converter suitable for driving a DC motor. It can also be one or more simple switches that supply three-phase current to an asynchronous motor. Numerous other embodiments and combinations of energy supply systems are known from which a person skilled in the art can choose depending on the drive technology used.

In a further advantageous embodiment, a performance parameter can be obtained by determining one or more parameters of one or more electrical conductor(s) which connect the power supply system of the drive machine to the network connection, for example the building power network.

The sensor system for determining the performance parameter comprises at least one sensor. In one embodiment, the sensor is a current sensor. The current sensor can be designed to be galvanically isolated from the electrical conductor, for example by measuring the magnetic flux density around the electrical conductor. Depending on the drive, it can be an AC sensor or a DC sensor. The current sensor can be designed in such a way that installation is possible without having to be electrically connected.

In a further embodiment, the sensor can be designed as a resistor which is interposed in the electrical conductor and across which a voltage drop is measured. The current of the conductor can be determined from the voltage drop. The voltage drop can be determined as the difference in voltage between two voltages to ground. In this way, the voltage applied to the drive machine can also be determined. In such an embodiment, the sensor is therefore a current and voltage sensor. A voltage sensor can also be designed in such a way that a voltage is picked up at a connection point of the electrical conductor without interposing a component. Other values such as power, phase shift and power factor can be determined from current and voltage.

The voltage and/or current can be determined in a time-resolved manner, which means that the sensor can also act as a frequency sensor. The sensor can be designed as a temperature sensor that measures the heating of a known resistance, which is indicative of the power transported via the electrical conductor. Numerous other designs for the sensors mentioned are conceivable. The statements just given are therefore only to be understood as examples.

Depending on the type of drive machine, it may be advantageous for the sensor system to include several sensors in order to obtain the performance parameter. In one embodiment, both the mains connection and the energy supply system can be designed as three-phase. In this case, the performance parameter can be determined using two sensors. In a further embodiment, the mains connection and the energy supply system can be designed as three-phase and additionally have a neutral conductor. In this case, the performance parameter can be determined using three sensors. If it can be assumed that the load on all phases is predominantly the same, only a single sensor can be used on a single phase.

In a further embodiment, it can also be advantageous to use several sensors of different types in combination to clearly determine the performance parameter, or to carry out a measurement at different points in the energy supply system. This is particularly the case when the drive machine is used as a brake, for example as a regenerative brake.

In one embodiment, the drive machine comprises an alternating current machine. Here it may happen that even with knowledge of the direction of rotation, it is not possible to determine whether the machine is working as a motor or generator using a single sensor, since, for example, no flow direction can be derived from alternating current measurement values. Here, for example, the power and the phase shift in the electrical conductor can be determined through the combination of voltage and current sensors, whereby a performance parameter consisting of total power and the information as to whether the drive works as a motor or generator can also be calculated. The ratio of current and voltage can also be used to determine whether the prime mover works as a motor or generator. If the drive machine is designed in such a way that when braking, the electrical power generated is dissipated via a shunt or another separate circuit, the operating mode of the machine can be determined via an additional sensor in the circuit mentioned. If the sensor already provides suitable data when the drive machine starts up, the data obtained in this way can also be used to determine whether the machine starts as a motor or generator, since, for example, a starting motor, in contrast to a generator, has a high electrical output at low speeds in the electrical conductor.

Numerous other combinations of sensors and evaluation methods are conceivable that enable the determination of the performance parameter mentioned above, so that the solutions mentioned are only to be understood as an example.

To calculate the load, a second sensor system is provided, which provides a parameter that is indicative of the direction of movement of the elevator car.

In one exemplary embodiment - alternatively or in addition to the acceleration sensor described below - the movement direction parameter is determined by at least one air pressure sensor. The air pressure sensor may be mounted at a point in the elevator shaft, which is preferably a location near one of the axial ends of the elevator shaft. In this case, the direction of movement of the elevator car can be determined by the fact that when the elevator car moves towards the sensor, the air column is compressed, as a result of which an increased air pressure is measured by the air pressure sensor. For example, if the air pressure sensor is located at the bottom of a vertical shaft, then as the elevator car travels, the air pressure sensor will detect a higher air pressure as the elevator car moves downward and a lower air pressure as the elevator car moves upward. The air pressure sensor can also be placed at the top of the shaft to measure a higher air pressure when the car is going up and a lower air pressure when the car is going down.

Likewise, the air pressure sensor can be attached to the elevator car. The air pressure sensor will then measure a higher air pressure during the travel of the elevator car when the elevator car moves in the direction of the side on which the air pressure sensor is attached and a lower air pressure when it moves in the opposite direction. In addition, the air pressure sensor can be used to measure hydrostatic pressure when installed on the elevator car. From the value measured in this way, for example, using the barometric altitude formula or a simple approximation thereof using the difference between two measured air pressures, for example an air pressure before the journey and an air pressure After the journey, the direction of movement of the journey can be derived. The air pressure sensor can also be attached to a counterweight of the elevator system.

In a favorable exemplary embodiment, in addition to the first air pressure sensor attached to a movable component of the elevator system, a second, static air pressure sensor is used, which can be used to calibrate the first air pressure sensor. The second air pressure sensor can be located in the elevator shaft, for example. Using suitable methods, for example subtracting the measured value of the first air pressure sensor from the measured value of the second air pressure sensor, external influences such as weather-related air pressure fluctuations or temperature influences can be compensated for.

In a further embodiment, the sensor system comprises one or more position sensors for determining the position of the elevator car. The position sensor can be designed so that it determines the absolute position of the elevator car in the shaft. The position sensor can also be designed so that it detects the position of the elevator car in relation to another component of the elevator system. The position sensor can detect the position of the elevator car indirectly by detecting the position of another part of the elevator system, such as a counterweight.

Various designs come into consideration as possible embodiments of the position sensor. Some of these embodiments determine the distance of two points and allow conclusions to be drawn about the position of the elevator car. Such sensors can also be referred to as rangefinders. Some of these embodiments determine the change in position as a function of time and may also be referred to as velocity sensors. All locations already described in connection with other sensors can be used as the installation location for the position sensor. It is also possible to determine the direction of movement of the elevator car in the operating room by determining the direction of movement parameter by the direction of travel of suitable parts of the elevator system, for example the traction sheave or the suspension element. The following, non-exhaustive list of possible designs provides examples of suitable position, distance and speed sensors: magnetic tape sensor, pulse generator and counter, (laser) interferometer, (laser) transit time measurement, (laser) phase modulation, (laser) Triangulation, luminous flux sensor, radar, ultrasonic range finder, Ultrasonic speed sensor, rotation encoder on the traction sheave, etc.

If it is not possible to determine the direction of movement of the elevator car directly from the movement direction parameter supplied by the position sensor, it may be necessary to determine the direction of movement of the elevator car from the difference between two measured positions, e.g. the movement direction parameter before travel and the movement direction parameter after the trip. Positions can also be determined while driving.

In a further embodiment, the sensor system includes one or more acceleration sensors. The acceleration sensor can be attached to all positions of the elevator system that experience an acceleration force when starting and braking the elevator car, in particular the elevator car or the counterweight as well as the traction sheave, the suspension element, the deflection roller or other parts of the elevator system that move during operation. The movement direction parameter can be derived from the signal from the acceleration sensor by determining whether the acceleration force acting on the sensor is smaller or larger than the acceleration due to gravity. For example, if the sensor is installed in or on the elevator car and the signal from the acceleration sensor corresponds to an acceleration force that is lower than that of the gravitational acceleration when the elevator car starts up, it can be concluded from the movement direction parameter measured by the acceleration sensor that the elevator car is moving downwards . Likewise, the movement direction parameter when starting up the elevator car will correspond to a higher acceleration if it is moved upwards. The effects naturally reverse when the acceleration sensor is installed on the counterweight.

In an advantageous embodiment, the signal from the acceleration sensor is evaluated using evaluation methods that increase the signal-to-noise ratio of the sensor. The evaluation method can be integrated in the sensor or in the logic unit. For example, a longer, eg 30 seconds - 5 minutes, moving time average of the sensor value can be formed in order to obtain a base value. For example, a further, shorter sliding means can be formed, the duration of which corresponds approximately to the acceleration time of the elevator car in normal operation.

For example, a movement direction characteristic can be obtained when the longer moving average is compared with the shorter moving average, e.g. a movement can then be inferred and a movement direction characteristic can be obtained if the longer moving average exceeds the shorter moving average by more than a predetermined value exceeds or falls below. The specified value can be in the range of 0.1 - 20%, e.g. 1 - 5%.

In a further embodiment, the sensor system comprises a number of sensors for determining the orientation of the rotating field with which the drive machine, which is designed as a three-phase machine, is supplied. The embodiment is based on the fact that the direction of rotation of the drive machine correlates with the direction of movement of the elevator car.

The sensors for determining the orientation of the rotating field can be sensors of the first sensor system for determining the performance parameter. Individual or all sensors of the first sensor system for determining the power parameter can therefore also be sensors of the second sensor system for determining the movement direction parameter.

The sensor system for determining the movement direction parameter based on the orientation of the rotating field can be designed as a simple rotating field measuring device and typically includes a voltage measurement of three phases at suitable locations on the electrical conductors that connect the drive machine to the energy supply system. Other arrangements are also conceivable, depending on the design of the drive machine or the energy supply system.

In one embodiment, the elevator system includes a counterweight. The counterweight serves, among other things, to reduce the force required to transport a fully loaded elevator car and thus make it possible to use a smaller drive machine.

The counterweight is typically dimensioned so that an empty elevator car and an elevator car loaded with the maximum load require the same force for transport. Typically, this means that with a half-loaded cabin, only a minimum of force and therefore performance is required. In this case we speak of a 50% compensation. Differently sized counterweights can also be used. A compensation of 10% to 90% of the maximum load is conceivable. For example Counterweights can be designed to compensate for around 30% of the maximum load. In some embodiments, the elevator system does not include a counterweight.

The presence of a counterweight means that it cannot be concluded from the power of the drive machine alone whether a predominantly empty cabin is being transported downwards or a predominantly full cabin is being transported upwards, since the same energy has to be used in both cases. In order to be able to determine the load of the car, information about the direction of movement of the elevator car is advantageous in addition to the power of the drive machine.

In one exemplary embodiment, the invention includes a method by means of which the load of the elevator car can be determined. The method can be implemented in the logic unit. Typically, the method includes measuring a performance parameter of the electrical conductors using a first sensor system and measuring the movement direction parameter of the elevator car using a second sensor system. The parameters measured by the sensor systems are provided to the logic unit. For this purpose, the parameter can be converted into a digital value. The conversion of the parameter can already take place in the sensor system or be a function of the logic unit. The parameter can consist of several partial values, for example if the sensor system includes several sensors and the parameter contains several measured values.

The method subsequently determines the power of the drive machine from the performance parameter and the direction of movement of the elevator car from the movement direction parameter. The method then determines the load of the elevator car based on the power and the direction of movement.

In one exemplary embodiment, the performance parameter of the drive machine is determined by the first sensor system when the power consumption of the machine has reached a stable value during operation (in steady-state operation). This performance parameter is indicative of the power consumption of the drive machine (e.g. in steady-state operation), ie indicates the power and/or allows the power to be determined using a unique function (e.g. by multiplying by a constant, applying another function, and /or access to those stored in a table Values).

The power consumption is also defined for the case that electrical power is generated and delivered by the machine. In this case, the performance parameter can indicate the (positive) absolute amount of power consumption or have a reversed (negative) sign. In the latter case, the sign of the performance parameter contains a statement about whether the prime mover absorbs or outputs power; in the former case, this information cannot be identified from the power consumption. In particular, the performance parameter can have a first (e.g. positive) sign when power is consumed and a second (e.g. negative) sign different from the first sign when power is output.

In an advantageous exemplary embodiment, the method only determines a power of the drive machine if a movement direction parameter was previously determined and it is clear from the movement direction parameter that the elevator car has moved and therefore the power of the drive machine was used to drive the elevator car.

In one exemplary embodiment, the second sensor system detects a movement direction parameter during operation, which indicates the direction of movement of the elevator car. For example, the direction of movement can be determined by determining the difference between the movement direction parameter and a previously determined reference value.

In one exemplary embodiment, a movement direction parameter is recorded before operation, i.e. before travel, and after operation, i.e. after travel. By determining the difference between the two movement direction parameters, for example by subtracting the values from each other, the direction of movement of the elevator car can be obtained.

For example, the direction of movement of the elevator car can be expressed as a positive value if the measured value is greater than the reference value, or the first sensor value is greater than the second sensor value (and vice versa). For example, a value of +1 may correspond to an elevator car traveling upwards and a value of -1 to a elevator car traveling downwards.

The movement direction parameter can serve to limit the solution space of a system of equations that calculates a load on the elevator car from the power of the drive machine in such a way that a clear determination is possible. To do this, the method can use the usual mathematical methods or also use algorithms or programs.

In an example, the power P (in W) is related to the load L (in kg) and the counterweight G minus the cabin weight (in kg) as follows: $$\mathrm{P}=\mathrm{d}\cdot \left(\mathrm{L}-\mathrm{G}\right)\cdot \left|\mathrm{v}\right|\cdot \mathrm{G}$$

Here |v| the absolute value of the cabin's speed (in m/s), g the gravitational constant, and d the direction of movement (+1 or -1 as stated above). For the sake of simplicity, other components (inertia, weight of the ropes) and friction are ignored in this example.

The absolute amount of the speed of the car in steady-state operation for a given elevator is typically known and can therefore be assumed as a constant.

From the above equation, the load L (note that d = 1/d): $$\mathrm{L}=\mathrm{G}+\mathrm{d}\cdot \mathrm{P}/\left(\left|\mathrm{v}\right|\cdot \mathrm{G}\right)$$

Here G and (|v|·g) can be viewed as constants known for the elevator. In this example, for a known value of P, two values are basically possible for the load, L = G + P / (|v| · g) and L = G - P / (|v| · g). Knowledge of d based on the movement direction parameter allows this ambiguity to be eliminated.

The example above is for simplifying illustration. Even for more complex calculation methods (e.g. taking into account other factors such as friction and inertia; calculating L using the power parameter directly without explicitly determining the power P, using machine learning algorithms, etc.) the basic principle applies that knowledge of the direction of movement Eliminates ambiguity in the above equation and allows a clear solution to the load.

One possibility for disruptive influences is, for example, the changing total load of the elevator system due to the different cable lengths of the suspension element at different positions of the elevator car in the shaft. Depending on the elevator system, this can be mechanical be compensated in a way. The other energy consumption of the elevator system, for example the basic consumption of the lighting system or energy supply system, can also influence the measured performance. In an advantageous embodiment, the method therefore includes a function for compensating for such interference.

The logic unit can also correlate the parameters with the values to be determined by comparing them with tables, characteristic curves or maps stored in the memory of the logic unit and thus deliver results. The results may be intermediate results used to determine a final result. The determination of the final result can be done in the same way as the determination of the intermediate results. Other methods or algorithms for determining the results, for example power and direction of movement from the parameters of the sensor systems, as well as determining the load of the elevator car from the intermediate results, such as neural networks or machine learning, can be part of the method.

The calculated or determined values can be stored by the logic unit. The calculated or determined values can also be transitive and discarded after the subsequent value has been determined. The calculated or determined values can be linked to other values that are not part of the process. In a further example, it may be advantageous if the method includes a calibration option, so that, for example, the sensor systems or parts thereof can be calibrated such that the values determined therefrom lie within a confidence interval. The calibration can be carried out by one or more calibration runs. In one example, the calibration includes a first learning run with an empty elevator car and a second learning run with a known load, for example the body weight of a fitter. In a further, advantageous example, the method includes the possibility of self-calibration. The values obtained through the calibration can be stored in the logic unit in the form of tables, characteristic curves or maps or the like.

In one embodiment, the method includes providing the measured, determined and/or calculated values in the form of a data set. The data set can be provided as already described in connection with the logic unit.

Fig. 1

eine schematische Darstellung eines Ausführungsbeispiels eines erfindungsgemäßen Aufzugsystems in einem Gebäude,

Fig. 2a

ein Beispielgraph zur Veranschaulichung des Zusammenhangs zwischen Last, Leistung und Bewegungsrichtung

Fig. 2b

eine beispielhafte Darstellung eines Ausführungsbeispiels eines Verfahrens zur Bestimmung der Last einer Aufzugskabine als Blockdiagramm

Various aspects of the invention are explained in more detail below using exemplary embodiments in conjunction with the figures.

Fig. 1

a schematic representation of an exemplary embodiment of an elevator system according to the invention in a building,

Fig. 2a

an example graph to illustrate the relationship between load, power and direction of movement

Fig. 2b

an exemplary representation of an exemplary embodiment of a method for determining the load of an elevator car as a block diagram

In Fig. 1 an exemplary elevator system 100 is shown, which can usually occur in this form in buildings, but also in ships or other vertically extending structures. The elevator system includes an elevator car 110, often also referred to as a car, and a counterweight 102 in a shaft 101. The shaft usually extends predominantly vertically, preferably with an inclination of less than 15°. Cabin 110 and counterweight 102 are suspended from a suspension element 103, which is guided over one or more deflection rollers 104. The design chosen for illustration corresponds to a 1:1 suspension with 50% weight compensation; It is known to those skilled in the art that numerous types of suspension with a different number or configuration of deflection rollers, counterweights and suspension means are possible.

The suspension element 103 is guided over a traction sheave 105 and driven by it. For this purpose, the traction sheave 105 is mechanically connected to the drive machine 120, so that the drive machine 120 can transmit mechanical energy to it. The prime mover 120 may include a transmission. Instead of a traction sheave 105, a drive drum or a direct drive may also be possible.

In the example shown, the prime mover 120 and traction sheave 105 are installed at the top of the elevator system 100. Typically, these and other parts of the drive are provided in a separate engine room (not shown), but the elevator system 100 can also be designed without an engine room. Alternatively, the engine compartment or the location where the drive components are housed can be also in other positions that do not necessarily have to be in close proximity to the elevator shaft 101. The drive components can form a unit with the elevator car.

The drive machine 120 typically also functions as a brake in order to enable controlled travel of the elevator car 110 even in the event of mechanical energy being released. The braking function can be guaranteed by the drive machine 120 in various ways, for example by a mechanical brake, which can also act as a parking brake, or by an electromotive brake, also known as a dynamo brake, as well as a direct current or countercurrent brake.

The drive machine 120 is connected to the energy supply system 121 via electrical conductors 122. The number of conductors here depends on the type of drive machine 120. For example, in the case of a separately excited synchronous motor, it may be necessary to provide an excitation current in addition to the rotating field, while this is not the case for asynchronous motors, direct current motors with commutators or permanent magnet synchronous motors case is. The wiring of the motor also influences the number of conductors required, e.g. in a delta connection, also known as a delta connection, there is no need for a neutral conductor in contrast to a star connection. In addition, the electrical conductors 122 can also be sensor lines or data connections that provide the energy supply system 121 with information about corresponding operating states of the drive machine 120. Numerous other drive forms and wiring options are known to those skilled in the art, so they will not be discussed in more detail here.

The energy supply system 121 is connected to the electrical conductors 123 to a network connection 124, which is, for example, a building power network. The network connection provides electrical energy to the energy supply system 121, although an implementation in the form of a network or network is not absolutely necessary; The connection 124 can, for example, also be powered alone by a dedicated generator, for example an emergency generator. Preferably, the mains connection 124 feeds the energy supply system 121 with a substantially constant nominal voltage and frequency. Depending on how the energy supply system 121 is designed, different designs are also possible for the electrical conductors 123, for example with one or more, for example three, external conductors. In In an advantageous embodiment, the mains connection is three-phase. In a further embodiment, the mains connection additionally comprises a neutral conductor.

The energy supply system 121 supplies the drive machine 120 with the energy necessary for operation. The design depends on the way in which the prime mover 120 is operated. In a typical embodiment, the drive machine 120 includes a permanent magnet synchronous motor. In this case, the energy supply system 121 is typically a frequency converter, also called a frequency converter, which feeds the drive machine 120 in a multi-phase manner with a variable frequency, which is ideally dependent on the current operating state of the drive machine 120 and is coordinated therewith. Other versions are particularly known from older elevator systems, for example the motor of the drive machine 120 can be a direct current motor that is fed by a rectifier, for example a converter, this rectifier forming the energy supply system 121 or part of it.

A particularly simple design of the energy supply system 121 is possible if the drive machine 120 comprises an asynchronous motor, since the supply system 121 only has the task of providing the correct coil wiring with a suitable supply through the mains connection 124. Further combinations of drive machine 120 and energy supply system 121 are possible, so that the options mentioned are just examples.

The elevator system 100 includes a first sensor system 130 for measuring a performance parameter of an electrical power flowing through the electrical conductors 122. Alternatively or in addition to this, the further first sensor system 131 can also measure a performance parameter of an electrical power flowing through the electrical conductors 123. The first sensor system 130, 131 includes a large number of possible sensors, the function of which has already been described individually and the possible combinations of which have already been described earlier. The first sensor system 130, 131 provides the performance characteristic of the logic unit 150 (dashed line).

The elevator system 100 includes a second sensor system 140 for measuring a movement direction parameter of the elevator car. In this example, the sensor system 140 is attached to the outer top of the elevator car 110, but can also be attached be attached to one of the outside sides or to the floor of the elevator car 110. The sensor system can also be attached to the inside or between the inside and outside cladding of the elevator car 110. Typically, the sensor system 140 is set up to determine the movement direction parameter based on air pressure, distance of the elevator car 110 from any point, or position of the car 110 or the like.

Alternatively or additionally, the elevator system 100 includes a further second sensor system 141 for measuring a movement direction parameter of the elevator car 110, which is placed near the drive machine 120, for example near the traction sheave 105, and the movement direction parameter based on properties of the drive system during operation, e.g. the direction of rotation of the traction sheave 105 is determined.

Alternatively or additionally, the elevator system 100 includes a further second sensor system 142 for measuring a movement direction parameter of the elevator car 110, which is placed on the counterweight 102. In principle, values such as those measured by the second sensor system 140 can also be determined by the second sensor system 142, with a value generally being obtained that correlates with the opposite of the direction of movement that the elevator car 110 is performing.

Alternatively or additionally, the elevator system 100 includes a further second sensor system 143 for measuring a movement direction parameter of the elevator car 110, which is placed at the bottom of the elevator shaft 101. In a further embodiment, the second sensor system 143 can also be attached to the ceiling of the shaft 101 or to one of the side walls. Typically, the sensor system 143 is set up to determine the distance of the elevator car 110 or the counterweight 102 in relation to the sensor system. Alternatively, the sensor system 143 can also be set up to detect the direction of movement of the elevator car 110 or counterweight 102 during operation.

The second sensor system 140-143 also provides the movement direction parameter to the logic unit 150 (dashed line).

The logic unit 150 determines the load of the elevator car from the performance characteristic of the first sensor system 130, 131 and the movement direction characteristic of the second sensor system 140-143. For this purpose, the power of the drive system 120 and the direction of movement of the elevator car 110 are typically first determined as an intermediate step. Typically, the logic unit is housed in the engine room and its dimensions can correspond, for example, to an expansion module in the nano-ITX form factor.

Fig. 2a serves to illustrate the exemplary graphical relationship between power P, direction of movement, load compensation L _A and load L. The power of the drive machine P was plotted against the load L, expressed as part of the maximum load. An approximately linear relationship is assumed. In addition, the speed of the elevator car is always the same during operation.

In the simplest case (dotted graph) there is no load balancing. Regardless of the load L of the elevator car, mechanical energy must be used when moving up and mechanical energy is released when moving down. When driving upwards, the necessary electrical energy that must be used by the drive machine corresponds to the maximum power P _max at maximum load. The empty cabin has its own weight, so the minimum power P _min must always be greater than 0. When shutting down, energy is released, which in the example shown can be partially converted into electricity by the drive machine or, for example, can also require electrical power through active braking. The electrical energy released, if dissipated, will be lower than the energy previously fed in due to conversion losses, which is expressed by the correction factor f. If the power P exceeds the maximum of what can be achieved in generator mode of the prime mover, it can be concluded that the prime mover works as a motor. The release of mechanical energy, including braking power, is expressed by a negative sign. For simplicity, it is assumed that P _min and -P _min are the same, but this is typically not the case. In the case mentioned without compensation, the direction of movement and the load L can be deduced from the power P alone.

In a further limit case, the load compensation corresponds to 50% of the maximum load of the elevator car. It can be seen that at the point of ideal compensation, i.e. at 50% of the maximum load, the energy required to transport the elevator car becomes minimal (P _min ). It can also be seen that the required maximum power decreases by 50% compared to a 0 compensation, so the drive machine can be dimensioned smaller. Furthermore, it can be seen that in the range of 0 - 50% of the maximum load, energy is released when the elevator car moves upwards; energy only has to be used in the range of 50 - 100% load. The exact opposite is true when shutting down. Since the dead weight of the elevator car is also compensated, P _min and - P _min are also smaller in this case than in the case without compensation.

It can be seen that even with knowledge of the power P, it is not possible to clearly determine the load L, since the graphs shown provide two solutions except in the special case L = 50%. In a concrete example, for example, it cannot be concluded whether an elevator car with a corresponding load of <50% is being moved upwards or an elevator car with a load of >50% is being moved downwards, since the same power P is required in both cases. A clear determination is only possible with knowledge of the direction of movement of the elevator car, since then one of the two straight lines is no longer available as a solution space.

Finally, another exemplary case with 25% compensation is considered, which can be chosen, for example, if the greatest energy savings are possible with this counterweight dimension due to the expected load distribution and the need for a larger drive machine is therefore justified. The observations made in connection with the 50% compensation apply equally in the load range from 0 - 50%. The point at which P _min is reached is expected to be at 25% load. Outside the range of 0 - 50%, it is again clearly possible to determine the load L from P alone; this range can be treated in approximately the same way as an elevator system without load compensation.

In general, it will be apparent to those skilled in the art that any load balancing values can be described by two load sections, one of the sections being a system without load balancing, and the second section being a system with 50% load balancing in the load range 0% to 2 L _A (in the case from 0% < L _A < 50%) or 50% to 2.(1 - L _A ) (in the case of 50% < L _A < 100%) can be approximated, where L _A corresponds to the balanced load.

In the Fig. 2a The observations made and the model based on them represent the basis for the procedure 200 Fig. 2b In a step 201, a performance parameter is measured which is indicative of the performance of the drive machine. The performance parameter can be provided by the first sensor system 130, 131. In a subsequent step 211, the performance of the drive machine is determined from the performance parameter. Ideally, the specific power includes information about whether the power is a driving power or a braking power. For example, braking power is expressed with a negative sign.

Independently of step 201, a measurement of the movement direction parameter of the elevator car takes place in step 202. The movement direction parameter can be provided by the second sensor system 140-143. In a subsequent step 212, the direction of movement of the elevator car is determined from the movement direction parameter. Steps 202 and 212 can be omitted if the load on the elevator car can be clearly determined from the power of the drive machine.

In step 220, the result values from steps 211 and 212 are calculated using a method based on the in connection with Fig. 2a The model described works, the load of the elevator car is determined.

In a specific embodiment, the elevator system 100 is a passenger elevator with 1:1 suspension and a counterweight with 50% compensation. The drive takes place with a gearless drive system 120, which includes a permanent magnet synchronous motor. The drive system is powered by a frequency converter as a supply system 121. The drive system 120 brakes mechanically and additionally electrically by dissipating the resulting electrical energy from the motor via a resistance network that is part of the supply system 121.

An inductive current sensor on one of the phases of the electrical conductors 123 and a voltage sensor on the same phase serve as the first sensor system 130. The second sensor system is an ultrasonic sensor 143, which provides a movement direction parameter by measuring the frequency shift of the reflection due to the Doppler effect, and an acceleration sensor 142 on the counterweight 102.

The sensor system 130 and the sensor system 142, 143 are connected to the logic unit 150 via a WLAN connection. The logic unit is housed in the engine room.

In a first example, the logic unit 150 evaluates the following parameters according to method 200:
The performance parameter contains the current of a conductor of the electrical conductors 123 during operation. From the performance parameter, it is calculated using a map that the drive machine 120 is operated as a motor with an output of 20 kW.

The frequency of the reflected ultrasound signal is determined from the movement direction parameter using a Fourier transformation and, through comparison with the higher-frequency original signal, it is determined that the elevator car is moving away from the sensor, i.e. upwards.

Based on the electrical power and the direction of movement, it is now determined by comparing it with a previously recorded table that an upward transport with a power of 20 kW corresponds to a load of 640 kg.

In a further example, the logic unit 150 evaluates the following parameters according to method 200: The performance parameter contains both current and voltage of a conductor of the electrical conductors 122 during operation in a time-resolved manner. By determining the phase shift, it is determined from the parameters that the drive machine 120 works as a generator and delivers a braking power of 5 kW to the energy supply system 121. Since this is braking power, the value is determined as - 5 kW.

From the movement direction parameter of the sensor system 142 on the counterweight 102, it is determined that the sensor measured a higher acceleration than the acceleration due to gravity when the elevator car 110 was braked at the end of the journey and it is concluded that the counterweight 102 moved downwards and thus the elevator car 110 moved upwards .

Based on the electrical power and the direction of movement, it is now determined by comparing it with a previously recorded table that upward transport with a power of -5 kW corresponds to a load of 30 kg.

Claims (13)

1. System for measuring the load in an elevator system (100) having an elevator cabin (110), an energy supply system (121) and a drive machine (120),

   the drive machine (120) being designed to move the elevator cabin (110) along a shaft (101),

   the energy supply system (121) being connected to a mains connection (124) via electrical conductors (123), and

   the drive machine (120) being connected to the energy supply system (121) via electrical conductors (122),

   - the system comprising a first sensor system (130, 131) for measuring a power characteristic value and the power characteristic value being indicative of the power of the drive machine, and the elevator system having an elevator control,
   characterized in that

   - the system comprises a second sensor system (140, 141, 142, 143) for measuring a movement direction characteristic value of the elevator cabin (110), and the movement direction characteristic value is indicative of the movement direction of the elevator cabin (110),
   and

   - the system comprises a logic unit (150), the logic unit (150) being configured to calculate a load of the elevator cabin (110) from the measured power and movement direction characteristic values, the logic unit (150) forming a unit which is functionally separate from the elevator control, which unit does not detect any operational status information from the elevator control.
2. System according to claim 1, wherein the elevator system (100) comprises a counterweight (102) and the mass of the counterweight (102) is in the range between 30% and 70% of the maximum load, wherein 0% of the maximum load corresponds to the weight of the empty elevator cabin (110).
3. System according to either of the preceding claims,
   characterized in that the first sensor system (130, 131) for measuring the power characteristic value comprises one or more of the following sensors:

   - current sensor;

   - voltage sensor;

   - power sensor;

   - frequency sensor;

   - thermal sensor;

   - power factor sensor.
4. System according to any of the preceding claims, characterized in that the second sensor system (140, 141, 142, 143) for measuring the movement direction characteristic value of the elevator cabin (110) comprises one or more of the following sensors:

   - air pressure sensor, by means of which a constant or dynamic air pressure can be determined;

   - position sensor for determining a position of the elevator cabin;

   - distance finder for measuring a distance of the elevator cabin from a known position;

   - acceleration sensor for determining the acceleration forces acting on the elevator cabin;

   - speed sensor for determining the speed of the elevator cabin;

   - rotational field direction sensor system for determining the orientation of the rotational field with which the drive machine is operated.
5. System according to claim 4, wherein the movement direction characteristic value of the elevator cabin is indirectly determined by the second sensor system detecting a movement direction characteristic value of the counterweight (102) from which the logic unit (150) derives the movement direction characteristic value of the elevator cabin (110).
6. System according to any of the preceding claims, characterized in that the first sensor System (130, 131) for measuring a power characteristic value is designed such that the power characteristic value is indicative of whether the drive machine (120) is operating as a drive or brake.
7. System according to any of the preceding claims, wherein the logic unit (150) is configured to calculate the mechanical power of the drive machine (120) from the power characteristic value and/or to calculate the movement direction of the elevator cabin (110) from the movement direction characteristic value.
8. System according to claim 7, wherein the logic unit (150) is additionally configured to calculate one or more of the following values: the torque of the drive machine (120), the integral of the torque of the drive machine (120) over time, the integral of the electrical power over time, the movement direction as a derivative of the position, the movement direction as a derivative of the acceleration, the movement direction as a derivative of the distance, the load, the load depending on the movement direction, the integral of the load over time, the sum of all loads at one or more intervals.
9. Method for determining a load of an elevator cabin (110) of an elevator system (100) according to any of the preceding claims, the method comprising:

   - measuring the power characteristic value of the electrical conductors (122, 123) by means of the first sensor system (130, 131);

   - measuring the movement direction characteristic value of the elevator cabin (110) by means of the second sensor system (140, 141, 142, 143);

   - determining the power of the drive machine (120) from the power characteristic value of the electrical conductors (122, 123);

   - determining the movement direction of the elevator cabin (110) from the movement direction characteristic value of the elevator cabin (110); and

   - determining the load of the elevator cabin (110) from the power of the drive machine and the movement direction of the elevator cabin (110).
10. Method according to claim 9, characterized in that the second sensor system (140, 141, 142, 143) supplies one or more parameters for measuring a movement direction characteristic value of the elevator cabin (110), from which parameters one or more of the following variables can be determined: acceleration, speed, movement direction, or position,
    and at least one of these variables being used for calculating the load.
11. Method according to any of claims 9 to 10,

    wherein the power of the drive machine (120) is determined from the power characteristic value of the drive system in constant operation by comparison with a characteristic map and/or solving a system of equations, and

    wherein the movement direction of the elevator cabin (110) is implemented by determining the

    difference between at least one sensor value and a further value, wherein the further value is a second sensor value or a reference value, and

    wherein the movement direction of the elevator cabin (110) is used to determine the load of the elevator cabin (110) as a unique solution from the power of the drive machine (120) using a system of equations or a characteristic map.
12. Method according to any of claims 9 to 11, wherein the first sensor system (130, 131), the second sensor system (140, 141, 142, 143) and the logic unit (150) are installed in an existing elevator system (100).
13. Use of the system according to claim 1 in an elevator system (100).

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