EP1156977B1 - Method and device for controlling a hydraulic elevator - Google Patents

Abstract

A method for controlling a hydraulic elevator whose car can be displaced by a hydraulic drive mechanism by hydraulic oil fed through a cylinder line or evacuated from said hydraulic drive mechanism by a pump that cooperates with a first control valve unit and a second control valve unit, wherein the flow the hydraulic oil is controlled by a measuring device and operation of the elevator can be controlled and regulated by a control apparatus. The load of the elevator car is determined by a load pressure sensor detecting pressure PZ in the cylinder line and is controlled preferably in a constant manner by changing the control of the second control valve unit in such a way that movement of the elevator car can be controlled in a very precise manner. When the elevator car is descending, the dropping pressure PZ in the cylinder line is regulated by changing the first control valve unit in such a way that the descending movement of the elevator-cabin can also be controlled in a very precise manner.

Description

The invention relates to a method for controlling a hydraulic elevator of the type mentioned in the preamble of claim 1 and on a device according to Preamble of claim 11.

Hydraulic lifts are used advantageously in residential and commercial buildings. she can serve the vertical transport of people and / or goods.

A control unit for a hydraulic elevator is known from US Pat. No. 5,522,479 of the two pressure sensors are present, one of which is on top of the pump facing side of a check valve is arranged while the other on the installed the hydraulic drive cylinder side of the check valve is. The signals from the two pressure sensors are fed to a controller which controls the Speed of the electric motor driving the pump is determined. This way, over the amount of hydraulic oil delivered per unit of time the speed of opening and closing regulated downward elevator.

From US-PS 5,040,639 a valve unit for an elevator is known, which is a pressure sensor is assigned, with which the pressure leading to the hydraulic drive of the elevator Line is detectable. With the help of this pressure sensor, a compensation of the pressure in the pre-launch phase. In addition, the main valve is a stroke sensor assigned, which is required in the start phase of an upward movement of the elevator Gain information about the flow of hydraulic oil.

WO-A-98/34868 describes a method and an apparatus for controlling a known hydraulic elevator, in which the speed of the elevator car by means of of a flow meter is detectable. Depending on the operating situation, the Signals this flow meter either the speed of the pump driving Electric motor controlled or regulated or the opening position of a valve varies. The control variable is therefore switched over during the cabin movement. Careful operation is therefore a prerequisite for smooth operation Coordination of the control and regulation parameters, which requires considerable effort.

Such a flow meter only then delivers a signal about the movement of the Elevator car if the elevator car has already started to move. Therefore the actual starting process, which is very important for the comfort of driving is not adjustable.

The invention has for its object to provide a method and an apparatus where the entire operation from standstill to maximum speed and can be reliably controlled or regulated again until standstill, the control and technical control effort should be minimal at the same time, namely without additional resources for Determination of the flow rate of the hydraulic oil.

The stated object is achieved according to the invention in a method of the generic type Art by the features specified in the characterizing part of claim 1 and in a Device solved by the features specified in the characterizing part of claim 9. Advantageous further developments result from the dependent claims.

An exemplary embodiment of the invention is described in more detail below with reference to the drawing explained.

Fig. 1

ein Schema des hydraulischen Aufzugs samt der Einrichtung zu dessen Steuerung,

Fig. 2

Diagramme für eine Aufwärtsfahrt und

Fig. 3

Diagramme für eine Abwärtsfahrt.

Show it:

Fig. 1

a diagram of the hydraulic elevator including the device for controlling it,

Fig. 2

Charts for an upward journey and

Fig. 3

Diagrams for a descent.

In the figure, 1 means an elevator car of a hydraulic elevator that is operated by a Reciprocating piston 2 is movable. The lifting piston 2 forms together with a lifting cylinder 3 a known hydraulic drive. There is one on this hydraulic drive Cylinder line 4 connected through which hydraulic oil can be pumped. The cylinder line 4 is on the other hand connected to a first control valve unit 5, which at least the Functions of a proportional valve and a check valve combined so that it either behaves like a proportional valve or like a check valve what depends on how the control valve unit 5 is controlled, which will be discussed. The proportional valve function can in a known manner with a main valve and a pilot valve can be achieved, the pilot valve by an electrical Drive, for example a proportional magnet, is actuated. The closed Check valve holds the elevator car 1 in the respective position.

The control valve unit 5 is advantageously connected via a pump line 8 Pressure pulsation damper 9 can be arranged, connected to a pump 10, by means of the hydraulic oil can be conveyed from a tank 11 to the hydraulic drive. The

Pump 10 is driven by an electric motor 12 to which a power supply part 13 is assigned. A pressure P _P prevails in the pump line 8.

Between the control valve unit 5 and the tank 11 there is a further line carrying hydraulic oil, namely a return line 14, in which a second control valve unit 15 is arranged. According to the invention, this control valve unit 15 allows the hydraulic oil to flow back almost without resistance from the pump 10 into the tank 11 when the pressure P _P has exceeded a certain threshold value. As a result, the pressure P _P cannot significantly exceed the said threshold value. It is now the case that this threshold value can be changed by an electrical signal, so that this control valve unit 15 can perform a pressure control function in a manner similar to a known proportional valve. To achieve this function, as in the case of a proportional valve, a main valve and a pilot valve can be used in a known manner, which is actuated by a proportional magnet which can be controlled electrically.

According to the invention, there is a load pressure sensor 18 in the cylinder line 4, preferably directly at the corresponding connection of the control valve unit 5, which is connected to a control unit 20 via a first measuring line 19. The control device 20 serving to operate the hydraulic elevator is thus able to recognize the pressure P _Z prevailing in the cylinder line 4. When the elevator car 1 is at a standstill, this pressure P _Z reflects the load on the elevator car 1. It will be described later on how this pressure P _{Z influences} control and regulating processes and how operating states can be determined. The control unit 20 can also consist of several control and regulator units.

It is advantageous on the cylinder line 4, again preferably directly on corresponding connection of the control valve unit 5, a temperature sensor 21 is arranged, which is connected to the control unit 20 via a second measuring line 22. Because Hydraulic oil has a viscosity that varies significantly with its temperature Control and regulation of the hydraulic elevator can be significantly improved if the Temperature of the hydraulic oil is included as a parameter in control and regulation processes becomes. This will be described in more detail.

A further pressure sensor, namely a pump pressure sensor 23, is advantageously present, which detects the pressure P _P in the pump line 8 and is advantageously arranged directly at the corresponding connection of the pump line 8 on the control valve unit 5. The pump pressure sensor 23 also transmits its measured value to the control unit 20 via a further measuring line 24.

A first control line 25 leads from the control unit 20 to the control valve unit 5 this control valve unit 5 is electrically controllable from the control unit 20. In addition leads a second control line 26 to the control valve unit 15, so that this also from Control unit 20 is controllable here. In addition, a third control line 27 leads from Control unit 20 to the power supply part 13, whereby the motor 12 on and can be switched off, but possibly also the speed of the motor 12 and so that the delivery rate of the pump 10 can be influenced by the control unit 20.

By controlling the control valve units 5 and 15 from the control unit 20 determines how the control valve units 5 and 15 behave functionally. Will the Control valve units 5 and 15 are not controlled by control unit 20, both behave Control valve units 5 and 15 basically like a different preload Check valve. Are the control valve units 5 and 15 by the control unit 20 through controlled by a control signal, they act as proportional valves.

It should also be mentioned here that the two control valve units 5 and 15 are combined in a valve block 28, which in the figure by one of these two Unit-comprehensive dashed line is indicated. This has the advantage that the Assembly work on the construction site of the hydraulic elevator is reduced.

Before going into the essence of the invention in detail, first of all Principle of operation explained: When the elevator car 1 is at a standstill, it is essential that the control valve unit 5 is now closed, which, as already mentioned, thereby achieves is that it receives no control signal from the control unit 20 via the signal line 25, that is acts as a check valve. The control valve unit 15 can also be closed, however this is not always the case. So it is possible that even at a standstill the elevator car 1, the pump 10 is running, that is to say hydraulic oil, but that which is being pumped Hydraulic oil flows back into the tank 11 via the control valve unit 15. Usually However, both control valve units 5 and 15 do not receive any control signals from at standstill Control unit 20 so that only the check valve function is possible in both cases.

The electrically uncontrolled control valve unit 5 closes automatically due to the effect of the pressure PZ which the elevator car 1 generates when this pressure PZ is greater than the pressure P _P. It has already been mentioned that in this state the load pressure sensor 18 indicates the load caused by the elevator car 1. According to the invention, the effective load of the elevator car 1 is determined and transmitted to the control unit 20. The control device 20 can thus recognize whether the elevator car 1 is empty or loaded and the size of the load is thus also known.

If the elevator car 1 is to move in the upward direction, the control unit 20 first activates the power supply part 13 via the control line 27 and thus sets the electric motor 12 in rotation, as a result of which the pump 10 starts to run and delivers hydraulic oil. As a result, the pressure P _P in the pump line 8 rises. As soon as this pressure P _P exceeds a value correlated with the tension of the check valve of the control valve unit 15, the check valve of the control valve unit 15 opens, so that the pressure P _P cannot initially exceed this value. If this pressure value, which will usually be the case, is lower than the pressure p _Z in the cylinder line 4, the control valve unit 5 remains closed and no hydraulic oil flows into the cylinder line 4. As a result, switching on the pump does not cause any movement of the lift, because in this case the entire amount of hydraulic oil delivered by the pump 10 is returned to the tank 11 via the control valve unit 15. In order to achieve a movement of the elevator car 1, according to the invention the control unit 20 can now control the proportional valve function of the control valve unit 15 via the signal line 26, so that a greater hydraulic resistance is set on the control valve unit 15.

This now allows the pressure P _P to be increased until the necessary amount of hydraulic oil can flow into the cylinder line 4 through the control valve unit 5. Part of the flow of hydraulic oil delivered by the pump 10 flows back into the tank 11 via the control valve unit 15. That part of the flow of hydraulic oil which is pumped by the pump 10 and which is not returned to the tank 11 via the control valve unit 15 flows through the control valve unit 5 acting as a check valve due to the prevailing pressure difference via the control valve unit 5 into the cylinder line 4, that is to say raises the elevator car 1 on. In this way, continuous control of the hydraulic oil flowing to the lifting cylinder 3 is possible without the speed of the pump 10 having to be regulated. The pump 10 only has to be designed in such a way that it can deliver a flow rate of hydraulic oil sufficient for the maximum speed of the elevator car 1 at the maximum expected back pressure at the nominal speed, taking into account the usual reserve factors and other margins.

It should also be noted here that the flow through the control valve unit 5 can be determined from the pressure difference, for example according to the following formula at a given temperature: Q = k q A v C f (Δ p v ) 2.3 where A _{v is} the valve area, c _{f is} also a known spring stiffness, k _{q is} an empirically determined coefficient, and Δp _{v is} the measured pressure difference across the control valve unit 5. If the valve area A _{v is} known, then the flow and thus the cabin speed can be estimated, which significantly improves the controllability of the cabin speed. If such a continuous calculation is carried out by the control device 20, redundant data about the movement of the elevator car 1 can also be obtained in this way. This also applies to the continuous integration of the measured values of the flow. The accuracy of the determination of the speed can be considerably improved by comparing the values determined by such calculations and the data based on these calculations for periods in which certain distances are covered with data about covered distances which are provided by switching elements arranged in the cabin shaft ,

The above-mentioned pressure difference Δp _v can be approximately replaced by the difference between the current measured values for the pressure P _Z and the pressure P _Z0 before the beginning of the cabin movement for certain sections of the movement, corresponding correction factors being used. If the pump pressure sensor 23 is present, it is calculated exactly by the difference between the pressures P _Z and P _P. The determination of the flow rate is thus considerably more precise than in the introductory US Pat. No. 5,040,639 and is not restricted to the beginning of the movement, that is to say very low speeds of the elevator car 1. At least during the start-up process, the determination of the flow rate, taking into account the pressure difference Δp _v = P _Z -P _{Z0, is} sufficiently precise so that the start-up process can be reliably controlled even without the pump pressure sensor 23 without an actual flow meter.

By opening the check valve of the control valve unit 5, the pressure P _Z measured by the load pressure sensor 18 increases. The pressure increase detected by the load pressure sensor 18 thus indicates the opening of the check valve of the control valve unit 5 even before the elevator car 1 has started to move, since the pressure build-up is first used up in compression work and to overcome the friction when the vehicle is at a standstill. It is now possible according to the invention to control or regulate the start-up phase for the elevator car 1 solely by means of this pressure increase. At the same time, it is possible that, depending on the pressure P _Z measured by the load pressure sensor 18, the control valve 20 actuates the proportional valve of the control valve unit 15 more or less because, as already mentioned, the control valve unit 15 is designed such that it acts like the control valve unit 5 as a check valve, if there is no control signal and that it acts as a proportional valve if it is controlled by control unit 20 via control line 26. The amount of the control signal determines the degree of opening of the proportional valve.

The control of the speed of the elevator car 1 during upward travel can thus According to the invention with the signal of the load pressure sensor 18 by varying the Degree of opening of the proportional valve of the control valve unit 15 take place. It will be are shown that according to the invention, the entire upward journey and also the Downward travel with the help of the load pressure sensor 18 and a setpoint generator for the Load pressure can be controlled or regulated. By time and / or path dependent Variation of a target value for the pressure and comparison with that of the load pressure sensor 18 a determined value is therefore possible.

When driving downwards, the pump 10 usually remains switched off. The control of the the lifting cylinder 3 flowing back through the cylinder line 4 to the tank 11 Hydraulic oil is now carried out solely by controlling the proportional valve Control valve unit 5. This flows from the pump-side connection of the control valve unit 5 Hydraulic oil through the return line 14. It passes through the control valve unit 15.

According to the invention, only the signal of the load pressure sensor 18 is evaluated in order to control the start of the movement of the elevator car 1. This can be done by evaluating the time profile of the pressure P _Z. If the elevator car 1 is at a standstill, the load pressure sensor 18 delivers the current load, as already mentioned.

During a downward run, the control valve unit 5 is opened using its proportional valve function using a characteristic curve dependent on the measured load signal, the pressure P _Z. As soon as the pressure P _P in the pump line 8 thereby opens the check valve of the control valve unit 5, the value of the pressure P _Z measured by the load pressure sensor 18 drops. This is an indication that the elevator car 1 can move so that the corresponding control procedure can be started by the control device 20. The actual movement begins as soon as the pressure drop exceeds a certain minimum value, the size of which is determined by friction losses and the compressibility of the hydraulic oil. The size and the gradient of the drop advantageously allow a statement to be made about the acceleration with which the elevator car 1 is acted on. From the acceleration, the speed can also be advantageously determined by integration and the distance covered by the elevator car 1 can also be determined by means of repeated integration. Data determined in this way are advantageously subjected to a plausibility check and, with regard to the required security, are also compared with other data sources, for example with position detectors which, in connection with the elevator control, serve to initiate creep speed and to stop the elevator car 1.

Because the load on the elevator car 1 is determined when it is at a standstill, it can be predicted when this pressure will be exceeded by the starting of the pump 10 and the control of the control valve unit 15, so that the control valve unit 5 opens. It is therefore possible for the increase in the pressure P _P in the pump line 8 to be reduced in stages or continuously by changing the control of the control valve unit 15. The object according to the invention is thus achieved in that the starting process can be controlled very sensitively. It is therefore also possible within the scope of the invention that the control device 20 adjusts itself adaptively. According to empirical values, the control unit 20 can contain preprogrammed values that adapt automatically during operation.

It has already been mentioned that the pump pressure sensor 23 is advantageously present. It is thus possible for the pressure P _P in the pump line 8 generated by the pump 10 and influenced by the second control valve unit 15 to be determined by means of this pump pressure sensor 23, so that the pressure in the pump line 8 can be measured and thus the step-wise or continuous change in the Reduction of the pressure rise can also be regulated if necessary. The control device 23 therefore does not have to make do with the predictable data for the pressure increase. Because it can generate additional data, it can effectively regulate the pressure P _P. At the same time, the automatic adaptation of the control unit 20 is even easier and more comprehensible.

This advantageously results in a further possibility, namely that the difference between the pressure P _Z determined by the load pressure sensor 18 and the pressure P _P determined by the pump pressure sensor 23 can be formed in the control unit 20 and that this difference is used to determine the flow of the hydraulic oil in the cylinder line 4 can be. A flow measurement is thus possible, so that a flow meter as in the prior art is unnecessary, which brings cost advantages. A plausibility check already mentioned is also possible.

To implement the function of determining the flow of the hydraulic oil, it is advantageous if the pump pressure sensor 23 is designed as a differential pressure sensor which determines a differential pressure P _D which is the difference between the pressure P _Z prevailing in the cylinder line 4 and the pressure prevailing in the pump line 8 Pressure P _P corresponds. This achieves higher accuracy.

The inclusion of the measured value of the temperature sensor 21 is advantageous because with the temperature of the hydraulic oil, its properties, in particular the viscosity, to change. The control unit 20 can measure the temperature sensor 21 during control the accuracy of the control can be improved because in particular the calculation of the flow of hydraulic oil under Taking into account the pressure difference becomes more accurate.

2 shows idealized diagrams for an upward journey. The uppermost diagram, referred to as the P _Z diagram, shows the course of the setpoints for the pressure P _Z for two different states of the elevator car 1 (FIG. 1), namely the curve P _ZSollL for the empty elevator car 1 and the curve P _ZSollB for a loaded elevator car 1. Before starting an upward journey, the respective load is determined by the load pressure sensor 18 (FIG. 1). The corresponding values, namely P _Z0L for the empty elevator car 1 and P _Z0B for the loaded elevator car 1, are shown on the P _Z axis.

The second diagram, called the a, v diagram, shows the setpoints for Acceleration and speed for the movement of the elevator car 1 at Upward movement. Curve a shows the acceleration, curve v the speed.

The third diagram, referred to as the dP _Z / dt diagram, shows the curve of the time derivative of the setpoint of the pressure P _Z , that is to say the required change in the setpoint of the pressure P _Z in the individual phases of the upward travel. The solid line curve is an example of a particular load. An example of another load is shown as a broken line.

In the fourth diagram, shown at the bottom, called the H diagram, the stroke is the Valve spindle of the control valve unit 15 (Fig. 1) shown. As mentioned earlier, is done at the upward movement the motion control by controlling this Control valve unit 15.

Common to all four diagrams is the time axis t. Individual times t _u0 to t _u9 are shown on this time axis, which represent characteristic times in the context of the control and regulation. The references to the individual partial diagrams are shown with dashed lines.

An upward travel of the elevator car 1 will now be described with reference to this diagram. The _start command for the upward _movement is issued at time t _u0 . The control unit 20 (FIG. 1) determines the current value of the load pressure sensor 18 at this point in time. Two values are shown in the P _Z diagram. In one case the elevator car 1 is empty and the current value of the pressure P _Z is P _Z0L . In the second case, the elevator car 1 is loaded and the current value of the pressure P _Z is P _Z0B . The pump 10 (FIG. 1) is switched on by the start command mentioned. It starts up and starts pumping hydraulic oil. It initially builds up only a very low pressure because the hydraulic oil delivered by the pump 10 flows back to the tank 11 via the control valve unit 15 acting as a check valve. The small pressure that builds up correlates with the force of the spring of the check valve 15. This phase is completed at the time t _u1 . It can be seen from the H diagram that the control valve unit 15 opens fully due to the build-up of the pressure in the pump line 8, since it is not actuated.

It should be mentioned that this pressure can only be measured if after a advantageous embodiment of the invention, the pump pressure sensor 23 is present.

During the period from t _u0 to t _u1 , the control unit 20 calculates, as in the subsequent phase, the period from t _u1 to t _u2 , the pressure in the pump line 8 is to be built up so that the movement of the elevator car 1 begins at the time t _u2 can. A lower pressure is required when the elevator car 1 is empty, and a higher pressure when the elevator car 1 is loaded. According to the invention, the pressure is to be built up at different speeds so that the elevator car 1 begins to move after the same time. As previously mentioned, the control unit 20 has the information about the load of the elevator car 1 available. The control unit 20 knows the load of the empty elevator car 1 as a constant, characterized by a pressure P _Z0L. From this value and the measured initial value P _Z0 , that is to say the value P _Z0B for a loaded elevator car 1, the control unit 20 calculates, for example, the load _ratio P _Z0B / P _Z0L , which therefore represents the current load as a multiple or as a percentage of the load of the empty elevator car 1. The load _ratio P _Z0B / P _Z0L is now used to calculate how the pump pressure must rise so that the pressure required to move the elevator car 1 is built up in the pump line 8 at the time t _u2 . This advantageously ensures that the time from the start command to the start of the movement of the elevator car 1 is always the same regardless of the load.

The increase in pressure in the pump line 8 is achieved in that the control unit 20 acts on the control valve unit 15 in such a way that the control valve unit 15 is actuated in the closing direction. The return flow of the hydraulic oil to the tank 11 is thus made increasingly difficult, which results in the desired pressure build-up. How this pressure build-up takes place is shown in the Pz diagram by the dashed lines P _PB for the loaded elevator car 1 and P _PL for the empty elevator car 1. If only the load pressure sensor 18 is present within the scope of the general inventive idea, the pressure build-up is controlled. If, however, the additional pump pressure sensor 23 is advantageously present, this pressure build-up can be regulated by the pressure build-up acting as a setpoint according to the curves P _PB or P _PL and by means of the actual pressure P _P measured by the pump pressure sensor 23 determining the control deviation and using it the control valve unit 15 is controlled.

In the P _Z diagram, horizontal reference lines are also drawn for the two load cases - empty and loaded elevator car 1. The lowest reference line represents the pressure P _Z0L . A further reference line is drawn by a differential pressure ΔP _dyn higher. The differential pressure ΔP _dyn represents a value that is necessary to overcome hydraulic resistances from standstill to the start of movement. The resistances are composed of the force of the spring of the check valve of the control valve unit 5 (FIG. 1) and the cylinder friction in the lifting cylinder 3. The differential pressure ΔP _{dyn also} includes a term that takes the compressibility of the hydraulic oil into account. In addition, the differential pressure .DELTA.P _{dyn is} also dependent on the pressure actually prevailing, so that it is advantageous to correct the value in accordance with the actual load, which is done, for example, by multiplying by the load ratio mentioned.

The H diagram shows that the valve control unit 15 is not yet _activated during the period from t _u0 to t _u1 , but that the control valve unit 15 is then actuated in the closing _direction in the period from t _u1 to t _u2 . In this H diagram, two curves are shown, namely a curve H _L , which shows the activation in the case of the empty elevator car 1, and a curve H _B , which shows the activation when the elevator car 1 is loaded. At time t _u2 , the pump pressure is just so high that the load of the elevator car 1 and the resistance to the movement are just being overcome.

The two curves H _L and H _B are drawn as a straight line for the sake of simplicity. However, it is advantageous if the pressure builds up initially quickly and then more slowly. Immediately before the time t _u2 , the pressure _build-up should take place so slowly that the check valve of the control valve unit 5 cannot suddenly open.

At time t _u2 , as already mentioned above, the pump pressure is then just so high that the load of the elevator car 1 and the resistance to the movement are just being overcome. For the subsequent period from time t _u2 to time t _u3 , the acceleration is increased from zero to a certain value. In order to achieve this linear increase in acceleration, the temporal increase in cylinder pressure P _{Z must be} approximately constant, which can be seen from the dP _Z / dt diagram on the one hand and the P _Z diagram on the other. According to the linearly increasing setpoint P _ZSollB for the loaded elevator car 1 or P _ZSollL for the empty elevator car 1, the regulation is again carried out by changing the actuation of the control valve unit 15. Since the acceleration of from time t _u2 to time t _u3 If the speed rises from zero to the final value, the vehicle starts up smoothly because the speed increases automatically. The maximum acceleration is reached at time t _u3 .

It should also be mentioned here in particular that a setpoint for the cylinder pressure P _{Z is} not required before the time t _u2 . The two setpoint _curves P _ZSollL and P _ZSollB drawn in the P _Z diagram therefore _{do not} begin until time t _u2 .

During the subsequent period from time t _u3 to time t _u4 , this acceleration is maintained, so that the speed increases linearly during this period.

Since it was recognized that the relationship between the acceleration a and the cylinder pressure P _Z P Zsoll = ( M Z A Z ) a Should -P Z0 exists, it would be assumed that with constant acceleration a the pressure P _{Z will} not increase any further. In the aforementioned formula, M _{Z means} the effective mass of the reciprocating piston 2 including the elevator car 1 and A _Z the area of the reciprocating piston 2. However, as can be seen from the P _Z diagram, the invention provides that the setpoint value P _ZSollB for the loaded elevator car 1 or P _ZSollL for the empty elevator car 1 continues to rise. The reason for this measure is that because of the increasing flow rate of the hydraulic oil through the control valve unit 5 (FIG. 1) and through the cylinder line 4, there is an increasing pressure loss. This pressure loss is compensated for by the increase in the setpoint. It can be seen from the dP _Z / dt diagram that there should be a slight increase in pressure accordingly. An analogous measure is necessary for the period t _u1 to t _u2 , but is not immediately apparent from the curve. Corresponding corrections must be taken into account in all phases of the movement of the elevator car 1.

From time t _u4 to time t _u5 , as can be seen from the a, v diagram, the acceleration a is reduced again to zero. This is achieved by the control unit 20 now _reducing the pressure P _Z somewhat in accordance with the setpoint _curves P _ZSollB or P _ZSollL . To achieve this, the control of the control valve unit 15 is now changed so that it is only very slowly actuated further in the closing direction. Accordingly, a reversal of the pressure change can be seen from the dP _Z / dt diagram. The linear decrease in acceleration then automatically results in a parabolic change in speed, i.e. a smooth transition to another speed.

According to the a, v diagram, the speed of the elevator car 1 remains constant from the time t _u5 to the time t _u6 , the acceleration is therefore zero. Accordingly, the hydraulic resistance no longer changes, which means that the setpoint P _ZSollL or P _ZSollB remains constant, which is also evident from the dP _Z / dt diagram. In this area, therefore, the control valve unit 15 can be regulated with a constant setpoint value, so that the stroke of the valve spindle of the control valve unit 15 only changes if a control deviation occurs.

It is advantageous if, in the period from time t _u5 to time t _u6, the control valve unit 15 is not _{activated on} the basis of a regulation, but is controlled directly. Any rule deviations are therefore ignored. This means that the speed is not adjusted. This manifests itself in increased driving comfort because control oscillations of the speed are safely avoided. The control valve unit 15 is accordingly activated with a constant setpoint.

From time t _u6 , elevator car 1 should now be braked according to the a, v diagram. This braking process begins at time t _u6 with the linear structure of the braking deceleration, so that the acceleration a is increased from the value zero to a final value -a. This linear increase in braking deceleration ends at time t _u7 . As mentioned for the change in acceleration between times t _u2 and t _u3 and t _u4 and t _u5 , this change in acceleration results in a parabolic course of the speed, so that the braking process now also begins very gently. This effect is caused by the fact that the target values P _ZSollL or P _{ZSollB are} reduced, which can be seen from the P _Z diagram and from the dP _Z / dt diagram. In accordance with these changing setpoints, the control valve unit 15 is therefore actuated in the opening direction.

From time t _u7 , the braking deceleration is no longer changed. The speed is now reduced linearly. This is again evident from the a, v diagram. Here again it applies that due to the changing flow rate, which is now falling here, the flow resistances change, i.e. are now falling. Accordingly, the target value for the pressure P _Z, namely, P and P _{ZSollL ZSollB} is from time t to time t _{u7 u8} slightly reduced to compensate for this change to the flow resistance.

In the period from time t _u8 to time t _u9 , the braking deceleration is changed linearly towards zero. The setpoint for the pressure P _Z , that is to say P _ZSollL or P _ZSollB , is correspondingly reduced further, now at a lower speed, which can be seen from the dP _Z / dt diagram. Here, too, there is automatically a parabolic course of the speed, that is to say a gentle braking to a standstill of the elevator car 1.

The specifications for the acceleration a, the speed v and the individual time segments from the point in time t _u2 to the point in time t _u9 are selected such that the destination is reached exactly from the starting point of the elevator car 1. Nevertheless, it is advantageous to use the usual shaft switching means such as magnetic or touch contacts when controlling the elevator car 1.

In the sense of an example in FIG. 2 it is shown how controlled by such shaft switching means the start of the delay is not triggered at time t _u6 , but only at time t ' _u6 . Accordingly, the end of the linear increase in the delay _shifts from time t _u7 to time t ' _u7 . In this example, the shaft switching device is then waited for to respond. As a result, braking takes place somewhat later, which can be seen from the a, v diagram in the same way as from the H diagram. For reasons of clarity, the corresponding representation of the processes in the P _Z diagram and in the dp _Z / dt diagram has been omitted.

If the response of the corresponding shaft switching means coincides with the associated pre-calculated times t _ux , that is to say, for example, t _u6 , which the control unit 20 can recognize, the predefined parameters are correct. However, if the response does not coincide, there is a need to correct the specified parameters. In this way it is possible to adjust the parameters automatically. When the elevator system is in operation, it is then not necessary to switch on a phase with so-called creep speed shortly before reaching the desired destination.

If the control device 20 is designed to be self-adapting accordingly, this is simplified Definition of parameters as part of the planning and commissioning of the elevator system considerably.

It should also be noted that, as can be seen from the H diagram after time t _u9 , the control valve unit 15 automatically runs again in the closed position as soon as the pump 10 is switched off and the pressure in the pump line 8 decreases again. This results from the reduction in pressure in the pump line 8 according to the curves P _PB and P _PL after the time t _u9 , as shown in the P _Z diagram.

The analog idealized diagrams for a downward journey are shown in FIG. 3. The type and structure of the four sub-diagrams correspond to those of FIG. 2, but here no values are shown in the P _Z diagram that relate to the pump pressure because the pump 10 does not run when driving downwards and the pump pressure is therefore not relevant is. Before the start of a downward journey, the respective load is determined by the load pressure sensor 18 (FIG. 1). In the a, v diagram, the curves are mirrored horizontally compared to FIG. 2 because of the reversed direction of travel, which means for FIGS. 2 and 3 that the vector of acceleration and speed can also be seen from the a, v diagrams. The dP _Z / dt diagram in turn shows the curve of the time derivative of the setpoint of the pressure P _Z.

In the fourth diagram, shown at the bottom, again referred to as the H diagram, is in the In contrast to FIG. 2, the stroke of the valve spindle of the control valve unit 15 is not (Fig. 1), but the stroke of the valve stem of the control valve unit 5, which, like mentioned earlier, the descent controls.

The time axis t is again common to all four diagrams. Individual times t _d0 to t _d9 are shown on this time axis, which in turn represent characteristic times in the context of the control and regulation. The references to the individual partial diagrams are shown with dashed lines.

A downward movement of the elevator car 1 will now be described with reference to these diagrams. The _start command for the upward _movement is issued at time t _d0 . The control unit 20 (FIG. 1) determines the current value of the load pressure sensor 18 at this time.

When driving downwards, the pump 10 (FIG. 1) is not switched on. Their run is not necessary because when driving downwards, the drive solely by the weight of the Elevator car 1 is effected. The proportional valve of the control valve unit 5 is still closed.

During the period from t _d0 to t _d1 , the control unit 20 in turn calculates the load _ratio P _Z0B / P _Z0L or another corresponding reference value for the effective load which is required during the downward travel in order to control the proportional valve of the valve control unit 5 in such a way that the desired ones Values for acceleration a and speed v can be achieved. This takes into account that, when the elevator car 1 is empty, a comparatively lower braking effect must be achieved by the control valve unit 5 than when the elevator car 1 is loaded.

In the period from the time t _d1 to the time t _d2 , the control valve unit 5 is now activated in such a way that the differential pressure ΔP _dyn mentioned during the upward _{travel is} compensated. This creates the prerequisites that the movement of the elevator car 1 can begin at the time t _d2 .

The drop in the pressure in the cylinder line 4 is now achieved in that the control device 20 acts on the control valve unit 5 in such a way that the control valve unit 5 is actuated in the opening direction. Hydraulic oil can thus flow from the lifting cylinder 3 through the control valve unit 5 in the direction of the tank 11. The now not controlled proportional valve of the second valve control unit 15 is closed, so that only the check valve of the second valve control unit 15 is effective. The hydraulic oil flows to the tank 11 via this check valve. It should also be mentioned that the value of the differential pressure ΔP _dyn does not contain a term of the force of the spring of the check valve of the control valve unit 5, but a term that corresponds to the force of the spring of the check valve of the second Control valve unit 15 corresponds. The two control valve units 5 and 15 advantageously have the same structure and the spring constants of the springs of the check valves are the same. Then the values for the differential pressure ΔP _dyn are the same for upward and downward travel and are advantageously corrected in the same way with regard to the effective load.

It should also be mentioned that when the proportional valve of the control valve unit 5 opens Small part of the hydraulic oil through the pump line 8 and the stationary Pump 10 can flow back into the tank 11 because such pumps regularly one Have leakage.

For the subsequent period from time t _d2 to time t _d3 , the acceleration is increased from zero to a certain value. In order to achieve this linear increase in acceleration, the drop in cylinder pressure P _{Z over} time must be constant, which can be seen from the dP _Z / dt diagrams on the one hand and the P _Z diagram on the other hand. According to the linearly falling setpoint P _ZSollB for the loaded elevator car 1 or P _ZSollL for the empty elevator car 1, the regulation is now carried out by changing the control of the control valve unit 5. Since during the period from the time t _d2 to the time t _d3 the acceleration a of If the speed rises from zero to the final value, the vehicle starts up smoothly because the speed increases automatically. The maximum acceleration is reached at time t _d3 .

During the subsequent period from time t _d3 to time t _d4 , this acceleration is maintained, so that the speed increases linearly during this period.

Here again it applies that the pressure losses change due to the increasing flow rate. Since the pressure losses increase with increasing flow rate, the setpoint value for the cylinder pressure P _Z must be slightly reduced during this phase, which manifests itself in a corresponding change in the actuation of the valve control unit 5. Corresponding corrections must be taken into account in all phases of the movement of the elevator car 1, as already mentioned during the ascent.

From time t _d4 to time t _d5 , as can be seen from the a, v diagram, the acceleration a is reduced again to zero. This is achieved by the control unit 20 now _increasing the pressure P _Z somewhat in accordance with the setpoint _curves P _ZSollB or P _ZSollL . To achieve this, the control of the control valve unit 5 is now changed so that it is only actuated very slowly in the opening direction. Accordingly, a reversal of the pressure change can be seen from the dP _Z / dt diagram. The linear decrease in acceleration then automatically results in a parabolic change in speed, i.e. a smooth transition to another speed.

According to the a, v diagram, the speed of the elevator car 1 remains constant from the time t _d5 to the time t _d6 , ie the acceleration is zero. Accordingly, the resistance no longer changes, which means that the setpoint P _ZSollL or P _ZSollB remains constant, which is also evident from the dP _Z / dt diagram. Control of the control valve unit 5 with a constant setpoint takes place in this area, so that the stroke of the valve spindle of the control valve unit 5 only changes if a control deviation occurs.

It is advantageous if, in the period from time t _d5 to time t _d6, the control valve unit 5 is not controlled on the basis of a regulation, but is controlled directly. Any rule deviations are therefore ignored. This means that the speed is not adjusted. This manifests itself in increased driving comfort because control oscillations of the speed are safely avoided. The control valve unit 5 is controlled accordingly with a constant setpoint.

From time t _d6 , elevator car 1 should now be braked according to the a, v diagram. This braking process begins at time t _d6 with the linear structure of the braking deceleration, so that the acceleration a is increased from the value zero to a final value -a. This linear increase in braking deceleration ends at time t _d7 . As mentioned for the change in acceleration between times t _d2 and t _d3 as well as t _d4 and t _d5 , this change in acceleration results in a parabolic course of the speed, so that the braking process now also begins very gently. This effect is caused by the fact that the target values P _ZSollL or P _{ZSollB are} increased, which can be seen from the P _Z diagram and from the dP _Z / dt diagram. In accordance with these changing setpoints, the control valve unit 5 is thus actuated in the closing direction.

From time t _d7 , the braking deceleration is no longer changed. The speed is now reduced linearly. This is again evident from the a, v diagram. The same applies here that the flow resistances change due to the changing flow rate, which is now falling here, i.e. it is now falling. As a result, the setpoint for the pressure P _Z , namely P _ZSollL or P _{ZSollB, is} increased slightly from the time t _d7 to the time t _{d8 in} order to compensate for this change in the flow resistance.

In the period from time t _d8 to time t _d9 , the braking deceleration is now changed linearly towards zero. Accordingly, the setpoint for the pressure P _Z , that is to say P _ZSollL or P _ZSollB , increases further, now at a higher speed, which can be seen from the dP _Z / dt diagram. Here, too, there is automatically a parabolic course of the speed, i.e. a gentle braking.

The specifications for the acceleration a, the speed v and the individual time segments from the time t _d2 to the time t _d9 are in turn chosen such that the destination is reached exactly from the starting point of the elevator car 1. Nevertheless, it is advantageous to use the usual shaft switching means such as magnetic or touch contacts when controlling the elevator car 1.

In the sense of an example, it is also shown in FIG. 3 how, controlled by such shaft switching means, the start of the delay is not triggered at time t _d6 , but only at time t ' _d6 . Accordingly, the end of the linear increase in the delay shifts from time t _d7 to time t ' _d7 . In this example, the shaft switching device is then waited for to respond. As a result, braking takes place somewhat later, which can be seen from the a, v diagram in the same way as from the H diagram. For reasons of clarity, the corresponding representation of the processes in the P _Z diagram and in the dp _Z / dt diagram has been omitted.

If the response of the corresponding shaft switching means coincides with the associated times t _dx , that is to say, for example, t _d6 , which the control unit 20 can recognize, the predefined parameters are correct. However, if the response does not coincide, there is a need to correct the specified parameters. This in turn makes it possible to automatically adjust the parameters. It is therefore not necessary, even when driving downhill, to switch on a phase with so-called slow travel shortly before reaching the desired destination.

If the control unit 20 is designed to be self-adapting accordingly, one can Adaptation also take place during the descent.

In order to determine the setpoint travel curves, the required time course of the pressure P _{Z is} determined from the setpoint values for the acceleration and the speed and is stored as a setpoint value-time series in a setpoint generator of the control unit 20 as the setpoint travel curve. The current actual value of the pressure P _Z is determined with the aid of the load pressure sensor 18 and compared with the target value. With the usual control engineering methods, the control command is generated from the difference between the actual value and the setpoint. This actuating command causes the control valve unit 15 to travel upward and the control valve unit 5 to travel downward.

According to the invention, it is therefore provided that when the elevator car 1 is at a standstill, the load on the elevator car 1 is determined by the load pressure sensor 18, which detects the pressure P _Z in the cylinder line 4, so that the upward travel of the elevator car 1 is regulated by changing the actuation of the second control valve unit 15 that a target travel curve that is dependent on the load on the elevator car 1 and that represents a time course of the pressure in the cylinder line 4 is compared with the continuous changes in the pressure in the cylinder line 4, the control command for the second control valve unit 15 being derived from the control deviation is generated, and that the downward travel of the elevator car 1 is regulated by changing the control of the first control valve unit 5 in such a way that a target travel curve which is dependent on the load on the elevator car 1 and which represents a time course of the pressure in the cylinder line 4 also the cont changes in the pressure in the cylinder line 4 are compared, the control command for the first control valve unit 15 being generated from the control deviation.

This is only for the entire ascent as well as for the entire descent the load pressure sensor 18 is necessary to reliably move the elevator car 1 regulate.

Various alternative configurations are possible within the scope of the invention. The Load pressure sensor 18 can, for example, be placed directly in the control valve unit 5 be, also in their pre-tax chamber.

It can also be advantageous if when driving upwards and downwards in the range of If the target driving curve decreases with decreasing speed, there is no regulation when driving upwards, the second control valve unit (15) and when driving downwards, the first Control valve unit (5) is controlled directly with a time-variable setpoint. in the The adaptation is carried out with the participation of those arranged in the cabin shaft Switching elements an adjustment of the setpoints and their change over time possible.

If necessary, in connection with the present invention Creep speed can be turned on before stopping the elevator car if due special circumstances the target position is not reached directly. The introduction and that The end of the creep speed is in a known manner through in the cabin shaft arranged switching elements triggered.

Claims (12)

1. Method for controlling a hydraulic lift having a lift car (1) which can be moved by means of a hydraulic drive which comprises a lifting piston (2) and a lifting cylinder (3) by hydraulic oil being able to be conveyed through a cylinder line (4) into the hydraulic drive (2, 3) or out of the hydraulic drive (2, 3) by means of a pump (10) and with the co-operation of at least one control valve unit (5, 15), that is to say, a first control valve unit (5) and optionally a second control valve unit (15), the flow of the hydraulic oil being able to be controlled by measuring means, the pressure in the cylinder line (4) being able to be detected by means of a load pressure sensor (18) and the function of the lift being able to be controlled and regulated by means of a control device (20) which carries out the method,
   characterised in that

   when the lift car (1) is in the idle position, the load of the lift car (1) is established by the load pressure sensor (18) which detects the pressure P_z in the cylinder line (4),

   the upward travel of the lift car (1) is regulated in such a manner by the control of the second control valve unit (15) being changed that a desired travel curve which is dependent on the load of the lift car (1) and which constitutes a time progression of the pressure in the cylinder line (4) is compared with the continuous changes of the pressure in the cylinder line (4), the adjustment command for the second control valve unit (15) being generated from the standard deviation,

   the downward travel of the lift car (1) is regulated in such a manner by the control of the first control valve unit (5) being changed that a desired travel curve which is dependent on the load of the lift car (1) and which constitutes a time progression of the pressure in the cylinder line (4) is compared with the continuous changes of the pressure in the cylinder line (4), the adjustment command for the first control valve unit (5) being generated from the standard deviation.
2. Method according to claim 1, characterised in that no adjustment is carried out during upward and downward travel in the range of the desired travel curve with constant speed, but, during upward travel, the second control valve unit (15) is directly controlled with a constant desired value and, during downward travel, the first control valve unit (5) is directly controlled with a constant desired value.
3. Method according to claim 1 or 2, characterised in that no adjustment is carried out during upward and downward travel in the range of the desired travel curve with decreasing speed, but, during upward travel, the second control valve unit (15) is directly controlled with a time-variable desired value and, during downward travel, the first control valve unit (5) is directly controlled with a time-variable desired value.
4. Method according to any one of claims 1 to 3, characterised in that the time change of pressure P_Z is evaluated by the control device (20) by the acceleration acting on the lift car (1) being established from the magnitude and gradient of this time change.
5. Method according to claim 4, characterised in that the speed of the lift car (1) is established by the acceleration being integrated.
6. Method according to claim 5, characterised in that the path travelled by the lift car (1) is established by the speed being integrated.
7. Method according to any one of claims 1 to 6, characterised in that the pressure P_P which is produced by the pump (10) and which is influenced by the second control valve unit (15) in the pump line (8) is established by means of a pump pressure sensor (23) so that the pressure in the pump line (8) can be measured and consequently the stepped or continuous change of the pressure rise can also optionally be regulated.
8. Method according to claim 7, characterised in that the difference of the pressure P_Z established by the load pressure sensor (18) and the pressure P_P established by the pump pressure sensor (23) is formed in the control device (20) and in that this difference is used in order to establish the flow of the hydraulic oil in the cylinder line (4) .
9. Method according to claim 7, characterised in that the pump pressure sensor (23) is constructed as a differential pressure sensor which establishes a differential pressure P_D which corresponds to the difference between the pressure P_Z present in the cylinder line (4) and the pressure P_P present in the pump line (8).
10. Method according to any one of claims 1 to 9, characterised in that the temperature of the hydraulic oil is established by means of a temperature sensor (21) which is arranged on the first control valve unit (5) and is taken into account by the control device (20) when the lift is being controlled.
11. Device for controlling a hydraulic lift, having a lift car (1) which can be moved by means of a hydraulic drive which comprises a lifting piston (2) and a lifting cylinder (3) by hydraulic oil being able to be conveyed by means of a pump (10) from a tank (11) through a pump line (8) to at least one control valve unit (5, 15) and, from that location, through a cylinder line (4), in which the pressure can be measured by means of a load pressure sensor (18), to the hydraulic drive, the mass flow of the hydraulic oil being able to be controlled and monitored by measuring means with the co-operation of at least one of the control valve units (5, 15), and wherein the pump (10) and at least one of the control valve units (5, 15) can be controlled by a control device (20), characterised in that

    a first control valve unit (5) and a second control valve unit (15) can be controlled by the control device (20),

    the control device (20) contains desired travel curves for the upward and downward travel in a desired value transmitter, each desired travel curve constituting a time progression of the pressure P_Z in the cylinder line (4),

    during upward and downward travel, the control device (20) compares the respective actual values of the pressure P_Z with the desired values and controls the second control valve unit (5) during upward travel and the first control valve unit (15) during downward travel in accordance with the standard deviation, and

    the control device (20) does not control the pump (10) when the lift car (1) is to carry out a movement in a downward direction.
12. Device according to claim 11, characterised in that

    a pump pressure sensor (23) is provided as measuring means and establishes the pressure P_P in the pump line (8),

    the signal of the load pressure sensor (18) can be supplied to the control device (20),

    the control device (20) is produced in such a manner that it can generate additional data from the signal of the load pressure sensor (18), by means of which data the pressure P_P can be regulated with the second control valve unit (15) being controlled by the control device (20).

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