EP1431225B1 - Elevator with hydraulic drive - Google Patents

Abstract

Lift comprises a hydraulic drive, measurement signal sensors for determining system states, and at least one electronically controlled valve (10) with a control unit having an arrangement for feeding back at least the measurement signals of the hydraulic pressure and the valve piston position. At least one 3/3-way valve (21) is provided for controlling the drive. An Independent claim is also included for a process for controlling a hydraulically driven lift. Preferred Features: The drive is a hydraulic revolving cylinder engine or a hydraulic linear drive (9a).

Description

The invention relates to a lift with a hydraulic drive, measuring signal pickups for detecting system states and at least one electronically controllable valve with a controller having a device for returning at least the measurement signals of the hydraulic pressure and the valve piston position.

Hydraulic lifts are known in different configurations. DE 36 29 032 A1, for example, describes a hoist which uses a hydraulic motor to drive a flexible drive means different from the carrying cable of the elevator and thus to move the elevator. Both hydraulic cylinders and hydraulic rotary motors are used as hydraulic drive.

Hydraulic lifts sometimes use hydraulic control valves. In this case, usually a system size is measured and fed to a controller, which calculates possible disturbances and compensates the hydraulic flow by changing the hydraulic valve position to compensate for the disturbances. In addition to the regulation of the oil flow, a regulation as a function of the elevator position is realized.

The disadvantage of such lifts is the poor control accuracy and speed and often unsatisfactory ride comfort. This is particularly due to vibrations in the hydraulic system, which can arise due to the low attenuation and the low natural frequencies of such a system. In such elevator systems, an accurate control of the elevator under varying operating conditions is usually not achieved.

From DE 696 02 923 T2 an electrohydraulic control valve is known, which controls the flow rate and / or pressure to a hydraulic load as a function of the detected valve position, the detected pressures and other measured states and a control signal. By an integrated control circuit, a fast and accurate control of the fluid is achieved.

From the publication MATSUDO, Takashi: "Hydraulic lift with valve lift feedback control", LIFT REPORT, July / August 1998 (Issue 4), pp. 113-117, a hydraulic elevator with the features of the preamble of claim 1 is known, which two / 2-way valves used. The mode of operation is as follows: When the elevator is at a standstill, the hydraulic pump continuously pumps into a hydraulic tank when the open valve is fully open. For upward travel, the open valve is closed, so that an increase in pressure takes place in the supply line to the hydraulic cylinder, whereby a hydraulic flow is established and the cylinder is moved upwards. For down travel, the second 2/2-way valve, the down valve, is fully opened and hydraulic fluid is released from the cylinder, resulting in the downward movement. However, this arrangement is disadvantageous. For example, depending on the cabin load different pressures and thus different driving speeds. The oil temperature and other system parameters also have an influence on the system behavior. As a result, for example, stops can not approach exactly. Due to the long dead time of the system and the generally poor controllability oscillations occur in the oil column, which must be damped by very complex control and regulation techniques.

In contrast, the invention has the object to improve a hydraulic elevator of this type.

This object is achieved with an elevator of the type 'eingangs'bezeichneten according to the invention that at least a 3/3-way valve is provided for driving the drive.

All pre-described problems in the generic state of the art can be avoided in principle, by providing a 3/3-way valve for controlling the drive. With such an electronically controlled 3/3-way valve, a precisely defined volume flow can be set on the valve. As a result, the changing load conditions of the cabin no longer play a role, since they can be compensated automatically in the valve. It is just not necessary to measure the speed of the elevator car and to take into account in the scheme, whereby the hydraulic column between the valve and the hydraulic drive on the one hand and the mechanism between the drive and the elevator car on the other hand cause no deterioration of the control properties and thus in particular no Vibrations and the like. May arise. The elevator position is only used in a higher-level control circuit for fine adjustment of the system properties.

By taking into account hydraulic pressure and valve piston position in the control loop, a significant improvement in the driving behavior of the elevator relative to the control system used in the prior art can be achieved. Thus, the valve delivers exactly the hydraulic flow that is necessary to achieve a specific target-driving behavior. A change of pressure in the pressure supply can be compensated automatically. The same applies to a change of the load state, which can be compensated so directly on the valve and not by a long dead time afflicted feedback, such as a position signal, the elevator car must be considered in the controller. It is such a quick precise control of the hydraulic volume flow directly on the valve possible, resulting in a significant improvement in the overall system behavior. Plant data and any operating parameters can thus already be taken into account in the regulator of the valve and are easily modifiable in order to take into account, for example, aging phenomena of the components. The flexible parameterization of the system and the ability to make changes to the control algorithm and the like. Only in the control programs of the controller and the valves, resulting in a significant cost reduction of the overall system.

A preferred embodiment of the invention is characterized in that the drive is designed as a hydraulic rotary motor or as a hydraulic linear drive. Depending on the application, one of the two embodiments of the drive can be advantageous. Thus, rotary engines at high delivery and high speed of the elevator make sense. A hydraulic linear drive is able to handle particularly high loads move, with both the maximum head and the maximum travel speed are limited.

A preferred embodiment of the invention is characterized in that in each case a 3/3-way valve is provided for the inlet and the outlet of the hydraulic rotary motor. The use of a separate valve for both connections of the drive offers a number of advantages over the conventional design with a combined inlet and outlet valve. Thus, it is possible to set the pressure in both lines separately from each other, which is necessary for example for jerk-free start of the elevator from standstill. In addition, any leakage in the drive can be fully compensated. On a change in the load state, which in a four-quadrant operation of the elevator causes the motor depending on the direction and load state once used as a drive and once as a brake, so can react very quickly and gently.

The drive is preferably equipped with a mechanical holding device, in particular a brake or a holding valve.

In a preferred embodiment of the elevator is provided that the at least one control valve is provided spatially directly on the drive, possibly in Flanschbauweise. Such attachment to the drive possible with particularly rigid connections ensures that no vibrations can occur in this part of the hydraulic circuit. The pressure medium flows set by the control valve directly reach the drive, without vibrations being able to form in long supply lines which impair the stability of the overall system. Overall, the control properties are thereby significantly improved.

A further embodiment of the invention is characterized in that the drive is arranged in the shaft head or shaft bottom. By such an arrangement of the elevator drive can be dispensed with an extra engine room. Such machine rooms, which are required in many conventional elevators, considerably increase the costs of the overall system, so that waiving them is definitely desirable. By using an electronically controlled hydraulic drive, drives of this type can be realized.

An embodiment of the invention is characterized in that the counterweight has the same mass as the elevator plus its half maximum load. By Such a weighted counterweight is a four-quadrant operation of the elevator possible. The motor is used both as a drive and as a brake depending on the load of the elevator car. Overall, such an interpretation of the elevator system has the advantage that the drive can be built very small and the system has good energy efficiency.

In one embodiment of the invention, it is provided that measuring signal pickups are provided for detecting hydraulic fluid temperature and / or elevator position and / or optionally further system states. Thus, a constant speed and accurate positioning of the elevator can be achieved at the breakpoints. In addition, the system security is increased because pressure medium leaks or other emergency conditions can be detected and compensated if possible.

The controller has in this case cascade structure, in which the regulation of valve piston position and hydraulic pressure in the inner control loop occurs and occurring control errors are compensated on the basis of further measured system conditions in an outer slow control loop to ensure, for example, an accurate entrance to the stops. By this cascade-like control structure can be vibrations due to the low Effectively prevent damping and long dead time of such a hydraulic elevator system and still achieve a high dynamic and stationary control accuracy.

It is advantageous that the valve has a device for compensating the hydraulic fluid temperature. The integration of automatic temperature compensation into the valve simplifies the system design and improves the system's behavior, as the different viscosities of the hydraulic fluid due to temperature changes are immediately taken into account and no longer have negative effects on system performance. So a trouble-free operation of the elevator is guaranteed at low as well as high stress.

It is advantageous that at least one electronic processor unit is provided with the regulator and / or for controlling the valve and / or the holding device. The use of electronic processor units, for example in the form of plug-in cards or other such components, allows precise control of the elevator in all operating areas. The connection to higher-level system controls is easily possible. By adapting the operating programs, wide ranges of systems and system configurations can be covered and quickly adapted to changing circumstances.

In order to avoid the disadvantages of the prior art described above, in particular the poor positioning accuracy and the insufficient handling of conventional hydraulic lifts and to allow automatic adaptation to various changing system parameters, the invention also relates to a method for controlling a hydraulically driven elevator.

This is characterized in that the measurement signals of the hydraulic pressure and the valve piston position are received in and / or on the valve and thus the controller controls the valve so that adjusts a necessary to achieve a desired system state of the elevator hydraulic flow. This method ensures that a hydraulic fluid flow is delivered directly to the valve, which is suitable for achieving the desired system state at any time. This is possible very precisely by taking into account both the hydraulic pressure and the actual valve piston position. By taking into account only variables that can be measured on or in the valve, a very fast controller behavior can be realized. Swinging of the system, vibrations or instability of the controlled system can thus be prevented. Thus, neither the low natural frequency of such a hydraulic Elevator still the fact that it is a very soft system, affect the controller result and thus the handling of the elevator.

An advantageous development of the method is characterized in that the measurement signals are recorded by other system states, in particular the elevator position, the controller thus determines a control error by comparing the actual state with the desired state of the elevator and with the valve of this control error Adjustment of the hydraulic flow to achieve the desired state compensated.

The consideration of further system states in a further, superimposed control loop makes it possible to compensate for any control errors that occur. This can be u.a. take into account slowly changing system parameters, such as aging phenomena. The system behavior can be positively influenced thereby and, for example, a direct entry into the elevator stopping points is made possible.

Fig. 1

eine schematische, dreidimensionale Ansicht eines Aufzuges nach der Erfindung mit hydraulischem Rotationsmotor,

Fig. 2

eine schematische dreidimensionale Ansicht eines Aufzuges nach der Erfindung mit hydraulischem Linearantrieb,

Fig. 3

eine Darstellung der erfindungsgemäßen Hydraulikschaltung für einen hydraulischen Linearantrieb sowie in

Fig. 4

eine erfindungsgemäße Hydraulikschaltung für einen hydraulischen Rotationsmotor.

The invention is explained in more detail below by way of example with reference to the drawing. This shows in:

Fig. 1

a schematic, three-dimensional view of a Elevator according to the invention with hydraulic rotary motor,

Fig. 2

a schematic three-dimensional view of an elevator according to the invention with hydraulic linear drive,

Fig. 3

a representation of the hydraulic circuit according to the invention for a hydraulic linear drive and in

Fig. 4

a hydraulic circuit according to the invention for a hydraulic rotary motor.

A generally designated 1 elevator according to the invention consists of an elevator car 2, which is connected via a flexible support cable 3 with a counterweight 4. The weight 4 is guided vertically displaceable in existing in the elevator shaft rails 5. The elevator car 2 is slidably mounted in guide rails 6. Instead of the support cable 3, a flat belt with steel wire inserts can be used.

The flexible support cable 3 is guided over a plurality of deflection rollers 7 and fastened with its two ends in the shaft head. Between elevator car and counterweight it runs via the traction sheave 8, which is driven by a hydraulic rotary motor 9. The drive 9 is an electronic valve 10, which is connected via two rigid lines 11 to the drive motor 9. A pressure medium supply 12, which provides both the high and the low pressure for the operation of the engine is connected via leads 13 to the control valve.

An alternative embodiment with a hydraulic linear drive is shown in more detail in FIG. In this case, the elevator car 2 is slidably mounted again in guide rails 6 and vertically displaced by a plunger hydraulic cylinder 9a. The hydraulic valve 10 is arranged in spatial proximity to the pressure medium supply 12 and connected via a single pressure medium line 11a to the hydraulic cylinder 9a.

The valve 10 is driven by a valve processor 26, which receives its control signals from a system processor 27. A higher-level system controller 28 coordinates the overall control of the system.

The hydraulic circuit for the operation of the elevator with a piston engine is shown in Fig. 3 in more detail. In this case, a hydraulic linear drive 9a is used to drive the elevator.

The hydraulic supply 12 consists of a hydraulic reservoir 14 and a load-sensing pump 16, which is driven by a motor 15 and provides the operating pressure of the system at the high-pressure connection 17. A working pressure limiting valve 18 ensures that the operating pressure of the system available at the connection 17 is kept constant. To secure a maximum pressure limiting valve 19 is still available, which protects the system against dangerous overpressure conditions. The returning oil is returned from the low pressure port 20 in the hydraulic reservoir 14.

The electronically controllable valve 10 is in its simple design for a linear drive from a 3/3-way valve 21, which is adjusted via an electronically controllable 4/3-way pilot valve 22. At the control valve 21 is a Wegmesssensor 23 for measuring the control piston position. In addition, a pressure sensor 24 for measuring the drive-side pressure and a temperature measuring member 25 for determining the hydraulic fluid temperature is present.

The measuring signals of the sensors are directed into a valve processor 26 which contains the regulator and to whose control output the electrical control input 27 of the pilot valve 22 is connected. The setpoint sizes for the piston position and the various system pressures are specified by the system processor 27, which calculates the necessary control variables in dependence on user preferences and by the system controller 28 not shown here, and transfers the necessary control variables to the valve processor 26.

Depending on these request quantities and the system variables measured by the sensors, the valve processor 26 calculates a manipulated variable for the pilot valve 22, which is set by the electric valve processor 27. As a result, the control piston is moved in the main valve 21 and its position is measured by the distance measuring sensor 23. Thus, a closed-loop control of the control piston can be achieved. By the measured discharge pressure to the linear drive 9a also the hydraulic pressure can also be controlled to the desired target value.

In addition to the regulation of the delivered hydraulic pressure in the inner control loop, the manifold occurring disturbances are compensated by a superimposed position control of the elevator. For this purpose, there is a displacement sensor 34a on the elevator, which receives its position in the shaft. By taking into account these measurement signals, the actual position is compared with the desired position and corresponding control errors by changing the desired values balanced on the valve processor 26. This allows an accurate positioning of the linear drive and thus reach the elevator car.

For leak-free holding the elevator at a certain point a pilot-operated check valve 29 is provided, which can be actuated by an electrically operated control valve 30. Furthermore, a stopcock 31 for maintenance and the like. Is provided.

The hydraulic control for operation with a hydraulic motor 9 is shown in Fig. 4 in more detail. In this case, a hydraulically actuated brake 32 is provided for holding the elevator at a certain position on the drive roller 8, which is operated by an electrically operated control valve 33. The brake is used to protect the elevator from falling in case of faults in the drive and is also used to hold the elevator at a standstill.

The structure of the hydraulic circuit is similar to that shown in Fig. 3. Here, however, two main control valves 21a and 21b are provided, which are each controlled by a separate electronically actuated pilot valve 22a and 22b. The Wegmesssensoren 23a and 23b, the pressure measuring sensors 24a and 24b and the temperature measuring elements 25a and 25b are also for each of the two control valves 21a and 21b available. The valves are connected on the input side to the high-pressure connection 20 and to the low-pressure connection 17 of the hydraulic supply 12. On the output side, the control valves 21a and 21b are coupled to the hydraulic motor 9 via two shut-off valves 31a and 31b by means of two short rigid pipes 11. In this case, a valve 21a is connected to the inlet and a valve to the outlet of the hydraulic motor 9.

The measurement signals of the sensors in the hydraulic circuit are again supplied to the valve processor 26, which calculates therefrom the control variables for the control inputs 27a and 27b of the pilot valves 22a and 22b as a function of the measured variables. The system processor 27 calculates analogous to above depending on other system sizes, the necessary hydraulic flows to and from the engine 9. For more precise control of the elevator speed and position, the hydraulic motor 9 additionally has a sensor 34, the signal from the system computer 27 to control the elevator position and Speed is used.

By using two separate control valves 21a and 21b for inlet and outlet of the hydraulic motor 9 can be realized particularly favorable driving characteristics of the elevator. To start the elevator, the pressure in the inlet and outlet to the drive 9 while holding the brake 32 so be biased that a jerk-free starting is possible. Also, a change of the load condition of the elevator car 2, for example by loading or unloading, can be compensated for by setting the corresponding pressures in the supply and discharge to the drive.

In addition to the already described temperature compensation in the valve itself, wear and tear in the motor or the valves are compensated by the control. Due to the existing in the valve and system processors 26 and 27 characteristics fields can ensure a constant behavior of the elevator over a long period.

Of course, the invention is not limited to the above embodiments, but in many ways changeable, without departing from the spirit of the appended claims. Thus, in addition to the types of drive described also other hydraulic drives are possible. The pressure supply can also assume different designs in order to achieve an optimum result for the existing system. In addition, a design with two control valves is possible for the linear drive, in which a cascade-shaped structure a favorable driving behavior for slow and fast driving is achieved.

Claims (12)

1. A lift comprising a hydraulic drive, measurement signal sensors (23-25) for detecting system states and at least one electronically controllable valve (10) having a regulator (26, 22) which has a device for feedback of at least the measurement signals of the hydraulic pressure and the valve piston position,
   characterised in that the electronically controllable valve (10) has at least one 3/3-way valve (21, 21a) for actuating the drive.
2. A lift according to claim 1 characterised in that the drive is in the form of a hydraulic rotary motor (9) or in the form of a hydraulic linear drive (9a).
3. A lift according to claim 2 characterised in that there is provided a respective 3/3-way valve (21a, 21b) for the feed and the discharge of the hydraulic rotary motor (9).
4. A lift according to one of claims 1 to 3 characterised in that the drive is equipped with a mechanical holding device, in particular a brake (8) or a holding valve (29).
5. A lift according to one of the preceding claims characterised in that the at least one valve (10) is provided spatially directly on the drive (9, 9a), optionally in a flange structure.
6. A lift according to one of the preceding claims characterised in that the drive (9, 9a) is arranged in the shaft top or the shaft bottom.
7. A lift according to one of the preceding claims characterised in that the counterweight (4) is of the same mass as the lift (2) plus half its maximum payload.
8. A lift according to one of the preceding claims characterised in that there are provided measurement signal sensors (23, 24, 25, 34, 34a) for detecting hydraulic fluid temperature and/or lift position and/or optionally further system states.
9. A lift according to one of the preceding claims characterised in that the valve (10) has a device for compensation of the hydraulic fluid temperature.
10. A lift according to one of the preceding claims characterised in that there is provided at least one electronic processor unit with the regulator and/or for control of the valve and/or the holding device (26, 27, 28).
11. A method of controlling a hydraulically driven lift according to claim 1 or one of the following claims characterised in that the measurement signals of the hydraulic pressure and the valve piston position are sensed in and/or on the electrically controllable valve (10) and the regulator controls the valve therewith in such a way that a hydraulic flow necessary to achieve a desired system state of the lift (2) is set.
12. A method according to claim 11 characterised in that the measurement signals of further system states, in particular the lift position, are sensed, the regulator determines therewith a regulating error by comparison of the actual state with the desired state of the lift and with the valve (10) compensates for that regulating error by adaptation of the hydraulic flow to achieve the desired state.

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