WO2003068651A1 - Control device for a hydraulic lift - Google Patents

Abstract

The invention relates to a control device for a hydraulic lift. The displacement of a cabin (1) is controlled by the flow of hydraulic oil via a cylinder line (11) from and to a hydraulic drive (2). Said displacement is achieved by the control of the hydraulic oil flow by means of a pump (13). According to the invention, the control device has a control and regulating unit (25), which contains three hierarchically arranged regulators (42, 43, 44), namely a position regulator (42), a speed regulator (43) and a pressure regulator (44). This permits the displacement of the cabin (1) to be solely controlled by the drive of a power actuator (24) of the motor (14) that operates the pump (13), whereby the destination of the cabin (1) can be attained without any creep prior to arrival at the desired position. The invention obviates the need for control valves and the power requirement is reduced.

Description

Control device for a hydraulic elevator

The invention relates to a control device for a hydraulic elevator according to the preamble of claim 1.

A control device for a hydraulic elevator is known from WO 98/34868 AI and the resulting US-A-6, 142,529. The motor and the valve unit driving the hydraulic pump can be controlled by the control device via a frequency converter. This control device is able to regulate the movement of the cabin. The control device is designed in such a way that either the control valve unit or the power supply part for the motor of the hydraulic pump is controlled. In those phases of operation in which the

Control valve unit is not acted regulating, the total energy expenditure is lower, because in the control valve unit no energy previously applied by the pump and motor unit is destroyed again. The total energy expenditure is therefore less. However, it is necessary that the cabin approaches the next stop at a much lower speed, the so-called creep speed, after the trip to Nor.

A hydraulic elevator is known from DE-Al-196 01 724, the control device for the working cylinder of which has a position controller, a pressure controller and a speed controller. The position controller acts on the one hand directly on a variable displacement pump and on the other hand on the speed and pressure regulator, which are both also acted upon by other elements of the control device, so that a complex control algorithm results. Depending on the operating state, the pressure regulator or the speed regulator acts on a proportional valve, which is important for controlling the flow of the hydraulic oil. At the moment of switching, discontinuities in the control cannot be ruled out. The flow of the hydraulic oil is also influenced by the variable displacement pump.

From EP 0 643 006 AI a control device is known which enables precise direct entry, that is, does away with creep speed. The control device acts on a valve arrangement. While the vehicle is accelerating and traveling at nominal speed, the cabin is not regulated, but only controlled. When the stopping position is approached, the cabin is in the deceleration phase after a certain algorithm controlled path-dependent. Here too, the generated control command acts on the control valve arrangement, which contains two throttle valves. The energy requirement of such a drive is thus higher than in the subject of WO 98/34868 AI, because the hydraulic energy generated by a pump by means of a motor is partially uselessly destroyed in these throttle valves.

A hydraulic elevator is known from WO 99/33740, in which a pressure accumulator is present. Here 4 valves have to be switched to control the up and down travel of the cabin. The control of the pump is not disclosed.

The invention has for its object to provide a control device for a hydraulic elevator, which is able to control the travel of the car so that crawl can be dispensed with, but which does not require energy-consuming throttle valves.

According to the invention, the stated object is achieved by the features of claim 1. Advantageous further developments result from the dependent claims.

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

1 shows a hydraulic diagram,

Fig. 2 is a general scheme of a control device and

Fig. 3 shows a detailed diagram of the control device.

In FIG. 1, the reference numeral 1 denotes a car of an elevator, which can be moved by a hydraulic drive 2. The power transmission from the hydraulic drive 2 to the cabin 1 takes place in a known manner by means of a rope 3, which is deflected via a roller 5 attached to the hydraulic drive 2. One end of the rope 3 is fastened to a building part 4, but can also be fastened to the guide rails (not shown) for the cabin 1. Known deviating arrangements of rope 3 and rollers 5 are possible, as are hydraulic drives of different design, such as pull and push cylinders. In this regard, FIG. 1 shows only one example. Also - ό - The direct drive of the cabin 1 by the hydraulic drive, as shown in WO 98/34868, is possible.

The hydraulic drive 2 consists of a cylinder 6, in which a piston 8 fastened to a piston rod 7 can be moved. The end of the piston rod 7 opposite the piston 8 carries the roller 5. The interior of the cylinder 6 is divided by the piston 8 into a first pressure chamber 9 and a second pressure chamber 10. The drive 2 of the illustrated embodiment is a so-called plunger cylinder, in which the two pressure chambers 9 and 10 are connected. So there is no seal on the piston 8 against the inner wall of the cylinder 6. At the point where the piston rod 7 emerges from the hydraulic drive 2, there is a seal so that the pressure chamber 10 is sealed. In this type of cylinder, the hydraulically effective cross section corresponds to the cross section of the piston rod 7.

A cylinder line 11 is connected to the first pressure chamber 9 and connects this pressure chamber 9 to a cylinder line shut-off valve 12. This cylinder line shut-off valve 12 is an electrically controllable OPEN-CLOSE valve, for example a solenoid valve. The cylinder line shut-off valve 12, on the other hand, is connected to a pump 13, which is driven by an electric motor 14. At the other connection of the pump 13, a storage line shut-off valve 15 is connected, which is also an electrically controllable OPEN-CLOSE valve. This storage line shut-off valve 15 is followed by a storage line 16 which leads to a pressure accumulator 17 which consists of at least one pressure accumulator 17.1. A further pressure accumulator 17.2 is shown, which is connected in parallel to the first pressure accumulator 17.1. The number of pressure accumulators 17.1, 17.2, 17.n contained in the pressure accumulator 17 advantageously depends, for example, on the required storage volume, which is related to the maximum distance to be covered by the cabin 1. The greater the maximum possible path, the more pressure accumulators 17.1, 17.2, 17.n are contained in the pressure accumulator 17. Both bladder accumulators and piston accumulators can be considered as pressure accumulators 17.

A branch of the storage line 16 leads to a charge pump 18 which is driven by an electric motor 19. The charge pump 18 is also a

Tank line 20 connected to a tank 21. Hydraulic oil is by means of the charge pump 18 can be requested from the tank 21 in the pressure accumulator 17. The electric motor 19 driving the charge pump 18 is advantageously automatically controlled by a pressure switch 22. The pressure switch 22 rests on the storage line 16, thus detects its pressure, which is denoted by P _s . If the pressure P _{s drops} below a predetermined lower value, the pressure switch 22 switches the electric motor 19 on, so that the charging pump 18 then pumps hydraulic oil from the tank 21 into the pressure accumulator 17, as a result of which the pressure P _s is increased until the pressure P _{s reaches} a predetermined upper value, after which the charge pump 18 is then switched off again. The charge pump 18 must therefore only run when the pressure P§ in the pressure accumulator 17 is too low. The pressure P _s can drop on the one hand because of unavoidable leakage losses via the charge pump 18, and on the other hand due to a drop in the temperature of the hydraulic oil due to environmental influences. If the temperature of the hydraulic oil rises as a result of such environmental influences, the pressure P _{s increases} . Since such a temperature increase never happens very quickly, it would not be necessary for this reason to provide a pressure relief valve between the pressure accumulator 17 and the tank 21, through which hydraulic oil increases in the pressure P _s in the

Tank 20 can be drained. The leakage losses of the charge pump 18 are in themselves sufficient to prevent the pressure P from increasing too much. Nevertheless, such a pressure relief valve can be present for safety reasons. A check valve 23 is advantageously arranged between the charge pump 18 and the pressure accumulator 17. This check valve 23 prevents leakage through the charge pump 18. Then the already mentioned pressure relief valve is definitely necessary. Other safety-relevant system parts such as pipe rupture protection and emergency drain are not drawn and described because such elements are not relevant with regard to the essence of the invention.

As already mentioned, the pressure accumulator 17 is a bubble or a piston accumulator. Its pressure P _$ changes depending on the movement of the cabin 1. However, this does not have a disadvantageous effect on the control or regulation of the path and speed of the cabin 1. The control of the path and speed of the cabin 1 is carried out by the control device according to the invention described later.

The predetermined values at which the pressure switch 22 switches the electric motor 19 on or off can advantageously be changeable by a control and regulating device 25. A pressure Pz prevails in the cylinder line 11, which corresponds to the pressure in the first pressure chamber 9 of the hydraulic drive 2. This pressure correlates with the load of the cabin 1.

Because the pump 13 is arranged between the cylinder line 11 and the storage line 16, when the cylinder line shut-off valve 12 is in the “OPEN” position, the pressure Pz in the cylinder line 11 acts directly on the pump 13 on the one hand and thus in the hydraulic drive 2 and, when the storage line shut-off valve 15 is in the "OPEN" position when the elevator is operating, on the other hand the pressure P _s in the storage line 16 and thus in the pressure accumulator 17. Compared to the prior art control valves for controlling the speed are therefore not required. The hydraulic circuit is therefore simplified compared to this prior art. The electrical drive energy required to operate the pump 13 for the motor 14 driving the pump 13 accordingly correlates with the pressure difference Pz - Ps _> when the pump 13 pumps hydraulic oil from the pressure accumulator 17 into the hydraulic drive 2, or with the pressure difference P _s - Pz when the pump 13 pumps hydraulic oil from the hydraulic drive 2 to the pressure accumulator 17. The pressure difference P _s - P _z or Pz - Ps can be negative, so that the pump 13 is then driven by the pressure difference in turn. As a result, the motor 14 can act as a generator, as is already known. So that such energy recovery is advantageously possible, the motor 14 is operated in a known manner by a power divider 24, which is a frequency converter, for example. The power controller 24 is controlled by the control and regulating device 25, which in turn receives commands from an elevator control system, not shown here. Only one control line 26 is shown, via which the commands are transmitted from the control panels of the elevator system to the control and regulating device 25.

If the elevator car 1 is at a standstill, the cylinder line shutoff valve 12 and the storage line shutoff valve 15, both controllable by the control and regulating device 25, are closed. They are therefore not activated when the cabin 1 is at a standstill.

If the cabin 1 is to move downward, the control device 25 opens the cylinder line shut-off valve 12 and the storage line shut-off valve 15 and the motor 14 operates in its first direction of rotation so that the pump 13 hydraulic oil promotes from the pressure chamber 9 in the pressure accumulator 17. The pressure difference Ps - Pz- acts on the pump 13. At the same time, this means that electrical energy for the operation of the motor 14 only has to be used as long as the pressure Pz is lower than the pressure Ps- Because a control valve can be dispensed with nor a corresponding pressure loss. This has a positive effect on the overall efficiency, thus enabling the elevator to be operated in an energy-saving manner.

If the cabin 1 is to move upward, the cylinder line shut-off valve 12 and the storage line shut-off valve 15 are also opened by the control device 25 and the motor 14 is operated in its second direction of rotation so that the pump 13 hydraulic oil from the pressure accumulator 17 into the Pressure room 9 promotes. The pressure difference P _z - P _s acts across the pump 13. At the same time, this means that electrical energy for operating the motor 14 only has to be used as long as the pressure P _{s is} less than the pressure Pz.

Since basically only one electric drive power corresponding to the respective pressure difference P _s - P _z or Pz - Ps has to be used, the electrical connection value for the motor 14 can be much smaller than with conventional hydraulic circuits. Consequently, the motor 14 required to operate the pump 13 must also be designed for a smaller nominal output. This results in cost advantages for the motor 14 itself, with connected load tariffing due to the smaller connected load and with power tariffing due to the smaller consumption of electrical energy. It is also avoided that hydraulic oil which has been brought to high pressure by means of a pump is expanded again in the direction of tank 21 and thereby releases or loses its potential energy uselessly.

Another advantage is that the tank 21 can be small. It actually only serves to absorb a differential amount of hydraulic oil that corresponds to the leakage losses. These leakage losses can flow through a leakage line 30 into the tank 21.

The pressure Pz in the cylinder line 11 can be detected with the aid of a load pressure sensor 31. It is transmitted to the control and regulating device 25. The pressure switch 22 already mentioned evaluates the pressure Ps in the storage line 16. The

Pressure switch 22 also includes the functionality of a pressure sensor. The one from him determined pressure in the storage line 16 is also transmitted to the control and regulating device 25. The control and regulating device 25 thus knows the two pressures Pz and Ps and is thus able to take these pressures into account when controlling or regulating the elevator, which will be explained in more detail with regard to the load pressure sensor 31 because this is relevant to the invention.

The hydraulic circuit described has the remarkable advantage that no proportionally pilot-controllable valve is required to operate the hydraulic elevator. Many conventional hydraulic elevator systems have separate pilot-controllable valves for ascending and descending. This effort is avoided by the invention. The control chain is therefore also very simple and clear, because the speed of the cabin 1 is controlled or regulated only by means of a single element, namely by means of the motor 14.

It was mentioned that when the elevator is operating, namely when the car 1 is moving, the cylinder line shut-off valve 12 and the storage line shut-off valve 15 must be open. If the cabin 1 is to be moved from a standstill, the cylinder line shut-off valve 12 and the storage line shut-off valve 15 must be opened. This operating situation, ie the opening of the cylinder line shut-off valve 12 and the storage line shut-off valve 15, is critical with regard to the pressure conditions and requires special measures for control. The reasons for this are explained below.

When the cabin 1 is at a standstill, the cylinder line shutoff valve 12 and the storage line shutoff valve 15 are closed. The pressure Pz is present on the cylinder line shutoff valve 12 on the side facing the drive 2, and the pressure Ps is present on the storage line shutoff valve 15 on the side facing the pressure accumulator 17. The pressure at the respective other connections, that is to say those at the pump 13 facing is not clearly defined. After a long standstill of the cabin 1, the pressure has decreased due to the leakage losses of the pump 13. On the one hand, a previously existing pressure difference between the two sides of the pump 13 has decreased, so that the same pressure prevails at the connections of the cylinder line shutoff valve 12 and the storage line shutoff valve 15 facing the pump 13. On the other hand, the pressure has increased due to the flow into the tank 21 via the leakage line 30 Hydraulic oil reduced, in the extreme case almost completely, so that within the pump 13 and at its two connections to the cylinder line shut-off valve 12 and the storage line shut-off valve 15 there is only a pressure which is hardly different from the atmospheric pressure.

It now follows that when opening the cylinder line shut-off valve 12 and

Storage line shut-off valve 15 sudden pressure changes occur, which are also noticeably noticeable by noise. The sudden pressure changes also put a considerable load on the pump 13, which can be disadvantageous for its operation and service life. These problems apparently also exist in the subject of WO-A-99/33740, where a total of four valves have to be switched. The control method described below eliminates the problems caused thereby and enables convenient operation.

The existing means such as pump 13, motor 14, pressure switch 22, power controller 24 and the control and regulating device 25 are also used to avoid the sudden pressure changes. However, this is not the subject of the present invention and is therefore not described here.

In the initial state when the cabin 1 is at a standstill, as already mentioned, the cylinder line shutoff valve 12 and the storage line shutoff valve 15 are closed and the electric motor 14 of the pump 13 is at a standstill. If the cabin 1 is to be set in motion, the electric motor 14 of the pump 13 is controlled in a first process step in such a way that it builds up pressure at the pump-side connection of the storage line shut-off valve 15. This pressure build-up occurs in that the motor 14 and pump 13 rotate slowly in the direction of rotation that hydraulic oil is delivered towards the storage line shut-off valve 15. However, the amount of hydraulic oil delivered is minimal because the cylinder line shutoff valve 12 and the storage line shutoff valve 15 are closed. Nevertheless, the desired pressure build-up takes place. The motor 14 is driven only for a very short time. This time period will be the first compensation time t _A t. It has been shown that a running time of approximately 100 to 300 msec at a reduced speed n _re d are sufficient to build up a pressure which corresponds approximately to the pressure Ps in the storage line 16. If the storage line shut-off valve 15 is now opened in a second method step, there is no sudden change in pressure, so that the problem described above does not exist when the storage line shut-off valve 15 is opened.

After the expiry of the compensation time I _AI , the motor 14 and thus the pump 13 are stopped again. In a third method step, which begins with the expiry of the compensation time t _A ι, the motor 14 remains magnetized, which is achieved by the control device 25 controlling the power controller 24 accordingly. The pump 13 is thereby able to absorb torque without starting to rotate. At that moment, the pressure Ps in the storage line 16 is present on the side of the pump 13 facing the storage line shut-off valve 15, while a more or less undefined pressure prevails on the side of the pump 13 facing the cylinder line shut-off valve 12, which pressure originally exists Initial state was hardly different from the atmospheric pressure and was then reduced indefinitely by the running of the motors 14 for the duration of the compensation time t _A i.

The length of time during which the motor 14 remains magnetized without rotating is referred to as the second compensation time t ₂ . During this compensation time t _A 2, the pressure difference between the two sides of the pump 13 can now decrease, which is a consequence of the internal leakage losses within the pump 13. It has been shown that this second compensation time t _{A2 should be} approximately 200 msec. At the end of the second compensation time t _A2 , the pressure on the side of the cylinder line shutoff valve 12 facing the pump 13 now corresponds approximately to the pressure Ps in the storage line 16, while on the other side of the cylinder line shutoff valve 12 the pressure Pz prevails in the cylinder line 11 , Since the pressures Ps and Pz are of the same order of magnitude, the cylinder line shut-off valve 12 can now be opened without there being an abrupt change in pressure of such a magnitude that problems caused by pressure surges and noises arise.

Now the cylinder line shutoff valve 12 and the storage line shutoff valve 15 are open. By driving the motor 14 of the pump 13 via the power controller 24, the journey of the cabin 1 can now begin, at most after a further compensation time t _A3 . The compensation time t _A 3 can be approximately 200 msec, but is not really necessary. 2 shows a general diagram of the control device, namely the control and regulating device 25, which is part of the control device and which is designed according to the invention. It should be emphasized here that this embodiment according to the invention is very suitable with regard to the hydraulic circuit of FIG. 1, but is not limited to the application together with this hydraulic circuit. Rather, the control and regulating device 25 according to the invention can be used in all conceivable hydraulic circuits. It is only essential that the movement control of the cabin 1 takes place without the cooperation of a control valve by the operation of the pump 13, which is driven by the electric motor 14, which in turn is operated by the power controller 24. The control and regulating device 25 thus generates control commands for this power controller 24, with which the control or regulation of the travel of the cabin 1 then takes place alone.

The previously mentioned elevator control, which is now provided with the reference number 40, supplies the control and regulating device 25 with information about the destination via the control line 26. At the same time, the control and regulating device 25 receives the information about the actual position of the cabin 1 (FIG. 1), specifically from a position encoder 41. This is advantageously an incremental encoder of high resolution, for example an absolute value encoder with a step size of 0.25 mm. In addition, the control and regulating device 25 receives information from the load pressure sensor 31.

On the output side, the power controller 24 is connected to the control and regulating device 25 and acts on the pump 13 (FIG. 1) via the electric motor 14 (FIG. 1). As already described, this controls the travel of the cabin 1 (FIG. 1). In addition, the control and regulating device 25 also controls the two switching valves, namely the cylinder line shut-off valve 12 and the storage line shut-off valve 15, but this is not explained in detail here, since this is not part of the subject matter of the present invention.

According to the invention, the control and regulating device 25 contains three hierarchically arranged regulators, namely a position regulator 42, a speed regulator 43 and a pressure regulator 44. The output of the position regulator 42 acts on the input of the speed regulator 43 and, as has already been stated hierarchically the output of the speed controller 43 to the input of the pressure controller 44. This Controller hierarchy according to the invention is essential for the solution of the task and also offers a number of advantages with regard to the driving comfort of the elevator.

As is known from the prior art, the control and regulating device 25 also contains a driving curve generator 45 and a speed sensor 46. The speed sensor 46 calculates the speed of the car 1 in a known manner from the change in the position of the car 1 over time Generator 45, which at the same time contains the control control, generates a target value for the position to be reached from the travel destination supplied by the elevator control 40 and delivers this to the input of the position controller 42. The position controller 42 designed as a PID controller can thus use the control deviation Generate correlating signal and deliver it to the downstream speed controller 43. This makes it possible for the speed controller 43, knowing the deviation between the actual value and the target value of the position of the cabin 1 (FIG. 1), to regulate the speed in such a way that it is possible to reach the target position with pinpoint accuracy without the need for slow travel in a direct entry. The speed controller 43 takes into account in addition to that of

Speed sensor supplied actual speed V _s also the setpoint for the speed that is given to it by the driving curve generator 45. In FIG. 2, the line on which the setpoint speed vs ₀ u is transmitted is identified accordingly with soii.

According to the invention, the output signal of the speed controller 43 does not reach the input of the power controller 24 directly, but is fed to the pressure controller 44 as an input signal. The signal of the load pressure sensor 31 is present at the second input of the pressure regulator 44. This pressure is a measure of the actual value of the acceleration. The value of the setpoint acceleration bs ₀ n specified by the driving curve generator 45 is present at a further input of the pressure regulator 44, which is why in FIG. 2 the corresponding line, on which the setpoint acceleration bs ₀ n transmits, is marked with bs ₀ u. This makes it possible in a very advantageous manner to readjust the pressure in the cylinder line 11 (FIG. 1), which leads to the fact that forces generated by the starting and braking process are hydraulically balanced. This means that the start-up and braking processes take place completely smoothly, as a result of which the user of the cabin 1 (FIG. 1) hardly notices starting and braking processes. FIG. 3 shows a detailed diagram of the control and regulating device 25, in which the same elements as in FIG. 2 are shown, and in addition a number of advantageous configurations are shown. The basic structure of the position controller 42, speed controller 43 and pressure controller 44 is the same. The position controller 42 actual and target value of the position of the cabin 1 (Fig. 1) are supplied, namely the actual position value Post _s t, which comes from the position sensor 41, to the "-" input, and the position target value Possoiu der from the driving curve generator 45 comes to the "- (-" - input. The position controller 42 is a PID controller which can be parameterized, which is indicated in FIG. 3 by an arrow Para. The parameter or parameters originate or originate from the driving curve generator 45 where this value or these values are stored, which is indicated on the driving curve generator 45 by an arrow Para pointing outwards.

According to an advantageous embodiment of the invention, the output of the position controller 42, which supplies the positioning command of the position controller 42, in contrast to FIG. 2, does not lead directly to an input of the speed controller 43, but to a first input of a speed controller control element 50 3 between the switching element 51 drawn in between the output of the position controller 42 and the first input of a speed controller control element 50 is temporarily not considered here. This is an optionally available element according to a further advantageous embodiment, which will be described later. The speed controller control member 50 is supplied with the target speed vs ₀ ιι at a second input. The cruise control controller 50 internally includes a multiplier 50M and a summer 50S. In the multiplier 50M, the target speed vs ₀ n is multiplied by a parameter, which in turn is indicated by an arrow Para. This parameter also comes from the driving curve generator 45. The product of the parameter and the target speed vs ₀ u reaches the summer 50M and is added there to the positioning command of the position controller 42. This added signal, which represents a corrected command of the position controller 42, reaches the "+" input of the speed controller 43. The advantage of this measure to correct the command of the position controller 42 is that the behavior of the

Setpoint influencing speed controller 43 is influenced by a pilot control. The aim is to design the setpoint formed by the feedforward control in such a way that the speed controller 43 has to cope with a smaller control difference. It then follows that the speed controller 43 can regulate with a larger proportional component and a smaller integral component, as a result of which it responds faster on the one hand and also significantly reduces the tendency to overshoot and undershoot. This improves control stability. This measure is particularly advantageous because it is a control chain of the three controllers position controller 42, speed controller 43 and pressure controller 44. With three controllers connected in series, the risk of instability is much greater.

The speed controller 43 has the actual speed vι _{st of} the cabin 1 (FIG. 1) available at the “-” input. The speed controller 43 can also be parameterized in the same way as the position controller 42, which in turn is indicated by the arrow Para. The speed controller 43, which is also a PID controller, generates a control command from the corrected command from the position controller 42 and the value of the actual speed Vr _st .

According to a further advantageous embodiment, this control command in turn does not arrive directly at the first input of the downstream pressure regulator 44, but quite analogously again at a pilot control stage, namely at a pressure regulator control element 52. This pressure regulator control element 52 becomes analogous to the speed regulator control element 50 Multiplier 52M and a summer 52S are formed. The multiplier 52M is supplied with the target acceleration bs ₀ ιι, which is supplied by the driving curve generator 45. The target acceleration bs ₀ ιι is multiplied by a parameter in the multiplier 52M. The target acceleration bsoii corrected in this way is then added in the summer 52S to the actuating command originating from the speed controller 43.

In this way, a corrected control command is generated, which arrives at the "+" input of the downstream pressure regulator 44. By means of the pressure regulator control element 52, precontrol takes place in the same way and with the same positive effects, as has been described above.

The pressure controller 44 is also a parameterizable PID controller. The corrected positioning command mentioned reaches its "+" input and the actual load pressure value pist, which comes from the load pressure sensor 31, reaches its "-" input. From the control deviation between the Actual load pressure value p _ls t and the corrected control command, the pressure regulator 44 generates a control signal for the power controller 24 connected to the output of the control and regulating device 25, which regulates the speed of the motor 14 (FIG. 1).

Analogous to the two previous control stages, feedforward control is also advantageous. Therefore, a speed controller control element 53 is connected to the output of the pressure regulator 44, which in turn consists of a multiplier 53M and a summer 53 S. The multiplier 53M can also be parameterized here. In this case too, the pilot control has the advantageous effect described above.

It was previously described that the signal at the "-" input of the pressure regulator 44 comes from the load pressure sensor 31. It can be so immediately. However, it is advantageous to switch a load correction element 54 between the load pressure sensor 31 and the “-” input of the pressure regulator 44. This load correction element 54 contains a memory 55 and a summing element 56. The signal from the load pressure sensor 31, the actual load pressure value pι _st , reaches an input of the memory 55 and also a first input of the summing element 56. The value stored in the memory 55 of a reference load pressure p _lst0 reaches a second input of the summing _element 56. This second input is an inverting input, which has the consequence that the difference pist - pisto is formed in the summing element 56. This the difference pτ _st - p _ls to reaches the "-" input of the pressure regulator 44.

This load correction element 54 enables a very significant improvement in the

Rule behavior of the pressure regulator 44. This is done in that before the start of a journey of the cabin 1 (FIG. 1), for example at the moment the doors are closed, the load pressure p _ls t prevailing at that moment as the reference load pressure pisto in the memory 55 is saved. Then changes, ie while driving the cabin 1 (Fig. 1), the load pressure pι _st , then reaches the "-" input of the pressure regulator 44 instead of

Last pressure pι _s t the difference pι _s t - pistö- The pressure regulator 44 does not have to regulate to the large pressure pι _s t, but to the much smaller difference pι _st - pι _st0 . This is extremely important because modern hydraulic elevators are operated at pressures in the range of 80 to 200 bar. The pressure regulator 44 does not have to compensate for small differences of a high value, but always only the much smaller ones

Difference pτ _st - ι _st0 . Because the reference load pressure ι _st o before the beginning of a journey of the cabin 1 (Fig. 1) is determined and the loading of the cabin 1 no longer changes after the start of the journey, with the regulation of the much smaller difference pι _s t - pi _st o only those during the journey due to dynamic processes such as acceleration and deceleration and Changes in friction caused caused changes in pressure. For this reason, the pressure regulator 44 can also be parameterized in a completely different way, namely much more cheaply, in that the proportional component is chosen larger and the integral component smaller. This not only leads to faster regulation, but above all means an increase in driving comfort.

The controller concept described in its advantageous variants also makes it possible through the parameterization of position controller 42, speed controller 43, pressure controller 44 and multipliers 50M, 52M and 53M that the parameterization can be varied in many ways. It is thus advantageously possible to fundamentally carry out the parameterization of the lifting and lowering of the cabin 1 differently. The parameterization can also be made dependent on the current position of the cabin 1. The dynamic behavior of the elevator also depends on the position of the piston 8 (FIG. 1) within the cylinder 6. According to this position, the effective height of the hydraulic column is of different heights with corresponding different properties, for example because of the compressibility of the hydraulic oil. In the control concept described above, certain parameters can be varied in a sliding manner while the cabin 1 is traveling. So they can

Control and driving characteristics are kept constant over the entire driving range of the cabin 1 from the top floor to the bottom floor.

The advantageous effect of the switching element 51 already mentioned is described below. This switching element 51 can switch the forwarding of the control command generated by the position controller 42 on and off. The switching element 51 is controlled by a comparator 58. On this comparator 58, the current actual position value Posι _st and a target position for starting the position control, which is denoted by Poss ₀ nsta _r t, are on the input side. The output signal of the comparator 58 is either "high" or "low", which means that the switching element 51 driven with this output signal is switched on or off. The background to this advantageous solution is as follows. In principle, the position controller 42 can be active in all phases of the operation of the elevator. But this is not necessary. If the car 1 (FIG. 1) starts to move after a standstill, first with an acceleration phase which then changes to constant travel, the position of the car 1 need not be regulated at all. It is sufficient to regulate the travel of the cabin 1 solely on the basis of the target values for speed and acceleration, namely target acceleration bs ₀ n and target speed vsoii. Only when the cabin 1 approaches its destination does it really take into account the position of the cabin 1. It is therefore advantageous to take the control command generated by the position controller 42 into account in the cruise control only when the cabin 1 is approaching its destination. The target position Possoiista _r t for the start of the position control is a position value that describes the position of the cabin 1 at which the deceleration phase is to begin. As soon as the current actual position value Pos _{lst reaches} the value for the desired position Possoiistart, the comparator 58 switches on the switching element 51. From this moment on, the control command of the position controller 42 is taken into account when regulating the travel of the cabin 1. The task according to the invention of reaching the stopping position without creep speed is thus achieved.

It should be emphasized here, however, that this object is also completely achieved when the switching element 51 and the comparator 58 are not present, because then the command from the position controller 42 is continuously taken into account in the cruise control of the cabin 1. The advantage achieved by switching element 51 and comparator 58 is that when position control is not really required, position controller 42 is not effective. Then only the other controllers in the control chain, namely the speed controller 43 and the pressure controller 44, are effective. Instead of three controllers, only two controllers are involved in the control process. This measure advantageously increases the stability of the control.

The parameters contained in the driving curve generator 45, which are supplied to the position controller 42, the speed controller 43, the pressure controller 44, the speed controller control member 50, pressure controller control member 52 and the speed controller control member 53, can be structured in the form of parameter sets. This can also be multi-dimensional tables that contain different parameter sets for different temperatures of the hydraulic oil. The invention has been described here on the basis of the hydraulic scheme according to FIG. 1. However, the invention is not restricted to this, since it can also be used in the same way for other hydraulic circuits.

Claims

claims 1. Control device for a hydraulic elevator, with which the movement of a cabin (1) through the flow of hydraulic oil through a cylinder line (11) from and to a hydraulic drive (2) can be controlled, the flow of hydraulic oil using a pump (13 ) which can be driven by a motor (14) which is operated by a power controller (24) on the basis of signals from a control and regulating device (25), taking into account data stored in a driving curve generator (45), and The flow of hydraulic oil can be blocked by valves (12, 15), characterized in that the control and regulating device (25) of the control device has three hierarchically arranged regulators (42, 43, 44), namely a position regulator (42), a speed regulator ( 43) and a pressure regulator (44), the output of the position regulator (42) at the input of the speed regulator (43) and the output of the speed regulator (43) at the input of the pressure control (44) acts. 2. Control device according to claim 1, characterized in that between the output of the position controller (42) and an input of the speed controller (43), a speed controller control member (50) is arranged which pilot-controls the speed controller (43). 3. Control device according to claim 2, characterized in that the speed controller control member (50) consists of a multiplier (50M) and a summer (50S), the multiplier (50M) having a target speed vs ₀ n with a from the driving curve generator ( 45) multiplies predetermined parameters and the totalizer (50S) adds the product of the set speed vs ₀ n and the parameters to the control command generated by the position controller (42) and supplies this sum to a "+" input of the speed controller (43). 4. Control device according to one of claims 1 to 3, characterized in that between the output of the speed regulator (43) and an input of the pressure regulator (44) a pressure regulator control member (52) is arranged which pilot-controls the pressure regulator (44). 5. Control device according to claim 4, characterized in that the pressure regulator control member (52) consists of a multiplier (52M) and a summer (52S), wherein the multiplier (52M) multiplies a target acceleration bs ₀ ιι by a parameter predetermined by the driving curve generator (45) and the totalizer (52S) adds the product of the target acceleration bs ₀ n and a parameter to the control command generated by the speed controller (43) and adds this Sum supplies a "+" input of the pressure regulator (44). 6. Control device according to one of claims 1 to 5, characterized in that between the output of the pressure regulator (44) and the input of the power controller (24), a speed controller control element (53) is arranged which pilot-controls the power controller (24). 7. Control device according to claim 6, characterized in that the speed controller control member (53) consists of a multiplier (53M) and a totalizer (53 S), wherein the multiplier (53M) a target speed vs ₀ n with one of the driving curve generator (45) multiplies predetermined parameters and the totalizer (53S) adds the product of the set speed Vs ₀ n and a parameter to the control command generated by the pressure regulator (44) and supplies this sum to the power controller (24). 8. Control device according to one of claims 1 to 7, characterized in that the output of the position controller (42) is followed by a switching element (51) through which the output signal of the position controller (42) can be switched off. 9. Control device according to claim 8, characterized in that the switching element (51) can be controlled by a comparator (58), the comparator (58) having a current actual position value Posι _s t with a predetermined position from the driving curve generator (45) Poss _o iis _tart compares and the switching element (51) switches on as soon as the current actual position value Posτ _{st reaches} the value for the target position Possoiistart. 10. Control device according to one of claims 1 to 9, characterized in that the control and regulating device (25) has a load correction element (54) which between a connection for the load pressure sensor (31) and a "-" - input of Pressure regulator (44) is arranged. 11. Control device according to claim 10, characterized in that the load correction element (54) consists of a memory (55) and a summing element (56), the signal of the load pressure sensor (31), the load pressure actual value pι _st , on one Input of the memory (55) and to a first input of the summing element (56), a value of a reference load pressure pι _st0 stored in the memory (55) reaches a second input of the summing element (56), the second second input of the summing element (56) is an inverting input, and that the output signal of the summing element (56) is fed to a "-" input of the pressure regulator (44). 12. Control device according to claim 11, characterized in that as the reference load pressure pι _st0 in the memory (55) that actual load pressure value pτ _{st can be} stored, which can be determined by the load pressure sensor (31) before the start of a journey of the cabin (1).