EP1156977A1

EP1156977A1 - Method and device for controlling a hydraulic elevator

Info

Publication number: EP1156977A1
Application number: EP00901018A
Authority: EP
Inventors: Sead Veletovac; Luigi Del Re
Original assignee: Wittur AG
Current assignee: Wittur AG
Priority date: 1999-02-05
Filing date: 2000-01-31
Publication date: 2001-11-28
Anticipated expiration: 2020-01-31
Also published as: EP1156977B1; IL143953A0; KR20010089756A; JP2002536270A; WO2000046138A1; ATE273914T1; DE50007477D1; US6510923B1; CN1339011A; ES2226771T3; CA2361596A1; CN1178837C

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

Method and device for controlling a hydraulic elevator

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

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

A control unit for a hydraulic elevator is known from US Pat. No. 5,522,479, in which two pressure sensors are provided, one of which is arranged on the side of a check valve facing the pump, while the other is installed on the side of the check valve facing the hydraulic drive cylinder . The signals from the two pressure sensors are fed to a controller which determines the speed of the electric motor driving the pump. In this way, the speed of the elevator moving up and down is regulated via the amount of hydraulic oil delivered per unit of time.

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

From WO-A-98/34868 a method and a device for controlling a hydraulic elevator are known, in which the speed of the elevator car can be detected by means of a flow meter. Depending on the operating situation, the signal from this flow meter is used to either control or regulate the speed of the electric motor driving the pump or to vary the opening position of a valve. The control variable is therefore switched over during the cabin movement. A prerequisite for jerk-free operation is therefore a careful coordination of the control and regulating parameters, which requires considerable effort. Such a flow meter also only delivers a signal about the movement of the elevator car when the elevator car has already started to move. Therefore, the actual starting process, which is very important for the comfort of driving, cannot be regulated.

The invention is based on the object of specifying a method and a device in which the entire operation from standstill to maximum speed and again to standstill can be reliably controlled, the control and regulating outlay at the same time being minimal should, namely do without additional means for determining the flow rate of the hydraulic oil.

The stated object is achieved according to the invention in a method of the generic type by the features specified in the characterizing part of claim 1 and in a device 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 explained in more detail below with reference to the drawing.

Show it:

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

Fig. 2 diagrams for an upward journey and

Fig. 3 diagrams for a descent.

In the figure, 1 means an elevator car of a hydraulic elevator, which can be moved by a reciprocating piston 2. The reciprocating piston 2 forms, together with a lifting cylinder 3, a known hydraulic drive. A cylinder line 4 is connected to this hydraulic drive, through which hydraulic oil can be delivered. The cylinder line 4, on the other hand, is connected to a first control valve unit 5, which combines at least the functions of a proportional valve and a check valve, so that it behaves either like a proportional valve or like a check valve, which depends on how the control valve unit 5 is controlled, what is still discussed. The proportional valve function can in a known manner with a main valve and a pilot valve can be achieved, the pilot valve being actuated by an electric drive, for example a proportional magnet. The closed check valve holds the elevator car 1 in the respective position

The control valve unit 5 is connected via a pump line 8, in which a pressure pulsation damper 9 can advantageously be arranged, to a pump 10, by means of which hydraulic oil can be conveyed from a tank 11 for 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 one

Control valve unit 15 is arranged. According to the invention, this control valve unit 15 allows the hydraulic oil to return from the pump 10 to the tank 11 almost without resistance when the pressure P _P has exceeded a certain threshold value. As a result, the pressure Pp 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, one can also use a main valve in a known manner and use a pilot valve 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 device 20 via a first measuring line 19. The control device 20 serving to operate the hydraulic elevator can thus be recognized, which pressure P _z in the cylinder line prevails 4 This pressure P _z are at a standstill

Elevator car 1, the load on the elevator car 1 again. Later it will be described how control and regulating processes can be influenced and operating states can be determined with the aid of this pressure Pz. The control device 20 can also consist of several control and regulator units A temperature sensor 21, which is connected to the control device 20 via a second measuring line 22, is advantageously arranged on the cylinder line 4, again preferably directly at the corresponding connection of the control valve unit 5. Because Hydraulikol has a viscosity that varies significantly with its temperature, the 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. 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. As a result, this control valve unit 5 can be electrically controlled from the control unit 20. In addition, a second control line 26 leads to the control valve unit 15, so that this can also be controlled by the control unit 20. In addition, a third control line 27 leads from the control unit 20 to the power supply part 13, whereby the motor 12 can be switched on and off, but possibly also the speed of the motor 12 and thus 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, it is determined how the control valve units 5 and 15 behave functionally. If the control valve units 5 and 15 are not activated by the control unit 20, both control valve units 5 and 15 basically behave like a check valve that can be preloaded differently. If the control valve units 5 and 15 are controlled by the control unit 20 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 advantageously combined in a valve block 28, which is indicated in the figure by a dashed line comprising these two units. This has the advantage that the assembly effort on the construction site of the hydraulic elevator is reduced. Before the essence of the invention is discussed in detail, the principle of operation will be explained first when the elevator car 1 is at a standstill that the control valve unit 5 is now closed, which, as already mentioned, is achieved in that it does not receive a control signal from the control unit 20 Received signal line 25, i.e. acts as a check valve The control valve unit 15 can also be closed, but this is not always the case.It is possible that the pump 10 is running even when the elevator car 1 is at a standstill, i.e. hydraulic oil requires that the hydraulic oil delivered flows back into the tank 11 via the control valve unit 15 In general, however, both control valve units 5 and 15 do not receive any control signals from the control device 20 when they are at a standstill, so that in both cases only the check valve function is possible

The electrically uncontrolled control valve unit 5 automatically closes due to the effect of the pressure PZ that the elevator car 1 generates when this pressure PZ is greater than the pressure P _P that the load pressure sensor 18 has already mentioned the load caused by the elevator car 1 in this state Indicates, according to the invention, the effective load of the elevator car 1 is determined and transmitted to the control device 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 urges hydraulic oil. This increases the pressure P _P in the Pump line 8 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. Is this pressure value, which will usually be the case, less 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 the total amount of pump 10 required Hydraulikols in this case via the control valve unit 15 i n The tank 11 is reclaimed. In order to achieve a movement of the elevator car 1, the control device 20 can according to the invention

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 required amount of hydraulic oil can flow into the cylinder line 4 through the control valve unit 5. Part of the flow of hydraulic oil required 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, thus lifting the elevator car 1 on. In this way, a stepless 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 using the following formula at a given temperature:

where A _{v is} the valve area, Cf is also a known spring stiffness, kq 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. 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 on distances covered, which are supplied by switching elements arranged in the cabin shaft the accuracy of the determination of the speed can be significantly improved.

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 _Z o 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 Pz and 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 = Pz - Pzo, is sufficiently precise that the start-up process can be reliably controlled without an actual flow meter even if the pump pressure sensor 23 is absent.

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 starting 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 controls 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 therefore be carried out 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 still be are shown that according to the invention, the entire upward movement and also the downward movement can be controlled or regulated with the aid of the load pressure sensor 18 and a setpoint generator for the load pressure. Regulation is thus possible by varying a setpoint value for the pressure as a function of time and / or distance and comparing it with the value determined by the load pressure sensor 18.

When driving downwards, the pump 10 usually remains switched off. The hydraulic oil flowing back from the lifting cylinder 3 through the cylinder line 4 to the tank 11 is now controlled solely by actuating the proportional valve of the control valve unit 5. The hydraulic oil flows from the pump-side connection of the control valve unit 5 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 Pz. If the elevator car 1 is at a standstill, the load pressure sensor 18 delivers the current load, as already mentioned.

During a downward travel, the control valve unit 5 is opened using its proportional valve function with 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 unit 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 upon. From the acceleration, the speed can also be advantageously determined by integration and, in addition, the distance covered by the elevator car 1 can also be determined. Data determined in this way is advantageously subjected to a plausibility check and, with regard to the required security, is also compared with other data sources, for example with position indicators which, in connection with the elevator control, serve to initiate creep speed and to stop the elevator car 1. The fact that when the elevator car 1 is at a standstill is determined, it can be forecast when this pressure will be exceeded by the start 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 that by changing the Activation of the control valve unit 15, the increase in the pressure P _P in the pump line 8 is reduced in stages or continuously.This solves the problem according to the invention that the starting process can be controlled very sensitively.It is therefore also possible within the scope of the invention for the control device 20 to adapt itself According to empirical values, the control unit can contain 20 preprogrammed values that adapt automatically during operation

It has already been mentioned that the pump pressure sensor 23 is advantageously present. It is therefore possible that the pressure P _P generated by the pump 10 and influenced by the second control valve unit 15 in the pump line 8 is determined by means of this pump pressure sensor 23, so that the pressure in of the pump line 8 is measurable and thus the step-wise or steady change in the reduction in 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 rise. Because it can generate additional data, it can effectively regulate the pressure P automatic adjustment of the control unit 20 is even easier and more executable

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 control unit 20 and that this difference is used to determine the flow of the hydraulic oil in the cylinder line 4 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, which has already been 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 that determines a differential pressure P _{D that} determines the difference between the pressure Pz prevailing in the cylinder line 4 and the pressure prevailing in the pump line 8 P _P corresponds to a higher accuracy The inclusion of the measured value of the temperature sensor 21 is advantageous because its properties, in particular the viscosity, change with the temperature of the hydraulic oil. If the control device 20 can take measured values of the temperature sensor 21 into account in the control, the accuracy of the control can in turn be improved, because in particular the calculation of the flow of the hydraulic oil taking into account the pressure difference also becomes more precise

2 shows idealized diagrams for an upward journey. The uppermost diagram, referred to as the Pz 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 Pzsoii for the empty one Elevator car 1 and the curve train PZSOIIB for a loaded one

Elevator car 1 Before the start of an upward journey, the respective load is determined by the load pressure sensor 18 (FIG. 1). The corresponding values, namely P _Z O _L for the empty elevator car 1 and P _ZOB 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 during the upward journey Curve a shows the acceleration, curve v the speed

The third diagram, referred to as the dPz / dt diagram, shows the curve of the time derivative of the setpoint of the pressure Pz, i.e. the required change in the setpoint of the pressure Pz in the individual phases of the upward journey. The curve shown with a solid line is an example of a specific load The dashed line shows an example of another load

In the fourth diagram, shown at the bottom, referred to as the H diagram, the stroke of the valve spindle of the control valve unit 15 (FIG. 1) is shown. As mentioned before, during the upward movement, the movement is controlled by actuating 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 the time t _u o. 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 Pz diagram. In one case the elevator car 1 is empty and the current value of the pressure P _z is P _ZOL - In the second case the elevator car 1 is loaded and the current value of the pressure P _z is P _ZOB - The pump 10 (FIG 1) switched on. 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 1. 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 here that this pressure can only be measured if, according to an advantageous embodiment of the invention, the pump pressure sensor 23 is present.

During the period from t "o to t _u ι calculated, the control unit 20, as in the subsequent phase, the period from t" to be set up ι to t _u, the pressure in the pump line 8, so that at time t _u2 the movement of the Elevator car 1 can begin. 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 should 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 _ZOL - OFF from this value and the measured initial value Pzo, that is to say the value PZOB when the elevator car 1 is loaded, for example, the control unit 20 calculates the load ratio P _Z OB PZO _L , 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 _ZO B / P _ZOL is now used to calculate how the pump pressure has to rise, so that at time t _u that is

Movement of the elevator car 1 necessary pressure is built up in the pump line 8. In order to is advantageously achieved 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 device 20 acts on the control valve unit 15 in such a way that the control valve unit 15 is actuated in the closing direction. This makes the backflow of the hydraulic oil to the tank 11 increasingly difficult, which results in the desired pressure build-up How this pressure build-up takes place is shown in the P _z diagram by the dashed lines P _PB for the loaded elevator car 1 and P _L for the empty elevator car 1. If only the load pressure sensor 18 is present within the general inventive idea, the pressure build-up is controlled advantageously the additional

If the pump pressure sensor 23 is 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 using the actual pressure P _P measured by the pump pressure sensor 23 determining the control deviation and using this to control the control valve unit 15. Diagrams are also for the two load cases - empty and loaded

Elevator car 1 - horizontal reference lines drawn in. The lowest reference line represents the pressure P _ZOL . Another reference line is drawn by a differential pressure _ΔPdyn . The differential pressure ΔPdyn represents a value that is necessary to overcome hydraulic resistances from standstill to the start of movement. The resistances settle together from the force of the spring of the check valve

Control valve unit 5 (Fig. 1) and the cylinder friction in the lifting cylinder 3. The differential pressure ΔP _d yn also includes a term that takes the compressibility of the hydraulic oil into account. Furthermore, the differential pressure ΔP yn is also dependent on the actual pressure, so that it is advantageous to adjust the value accordingly to correct 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 "o to t", but that the control valve unit 15 is then actuated in the closing _direction in the period from t _u ι to t _u2 -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 the time t _u2 , the pump pressure is then just as great, 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 _build-up is initially quick and then slower Immediately before the time t _u2 , the pressure _build-up should take place so slowly that there is no sudden opening of the Check valve of the control valve unit 5 can come

At time t _u2 , as already mentioned, the pump pressure is then just so great that the load of elevator car 1 and the resistance to movement are just being overcome. For the subsequent period from time t _u2 to the time, the acceleration applies is increased from zero to a certain value In order to achieve this linear increase in acceleration, the temporal increase in cylinder pressure Pz must be approximately constant, which can be seen from the dPz / dt diagram on the one hand and the Pz diagram on the other hand. According to the linearly increasing setpoint PZSOIIB for the loaded elevator car 1 or PZSOII for the empty one

Elevator car 1 is then regulated again by changing the control of control valve unit 15. Since the acceleration increases from zero to _instant t ^ during the period from time t _u2 to time t ^, a gentle approach takes place automatically, because there is automatically a parabolic increase the speed At time t _u3 the maximum acceleration is reached

It should also be mentioned here in particular that a setpoint for the cylinder pressure Pz is not required before the time t _u. The two setpoint _curves P _ZSOÜL and PZSOI _I B drawn in the Pz diagram therefore do not begin until the time t _u2

This acceleration is maintained during the subsequent period from the time to the time t _u , so that the speed increases linearly during this period

Since it was recognized that the relationship between the acceleration a and the cylinder pressure Pz

"zSoll - \.) ^a Soll" l zo

A ^x z, exists, it would be assumed that the pressure P does not increase any further with constant acceleration a. 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. As can be seen from the Pz diagram, however, the invention provides that the setpoint PZSOIIB for the _Loaded elevator car 1 or P _ZSOIIL for the empty elevator car 1 continues to _rise.The reason for this measure is that due to the increasing flow rate of the hydraulic oil through the control valve unit 5 (FIG. 1) and through the cylinder line 4, an increasing pressure loss arises this pressure loss is compensated. It can be seen from the dPz dt diagram that there should be a slight increase in pressure accordingly. An analogous measure is necessary for the period t ₁ to t _{u 2} , but is not immediately apparent here from the course of the curve in all phases of the movement of the elevator car Corresponding corrections must be taken into account

From time t _u to time t _U 5, 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 applying the pressure P _{z in} accordance with the setpoint curves PZSOIIB or PZSOIIL Somewhat reduced To achieve this, the control of the control valve unit 15 is now changed so that it is only operated very slowly in the closing direction. Accordingly, a reversal of the pressure change can be seen from the dPz / dt diagram from the linear decrease in the acceleration there is then automatically a parabolic change in speed, i.e. a smooth transition to a different speed

From the point in time t _u5 to the point in time t 6, the speed of the elevator car 1 remains constant according to the a, v diagram, the acceleration is therefore zero. Accordingly, the hydraulic resistance also no longer changes, which means that the setpoint P _ZSOIIL or P _ZSOIIB remains constant, which can also be seen from the dPz / dt diagram. In this area, control valve unit 15 can therefore be regulated with a constant setpoint value, so that the stroke of the valve spindle of control valve unit 15 changes only in the event of a control deviation. It is advantageous , if in the period from time t _U 5 to time t “6

Activation of the control valve unit 15 does not take place on the basis of a regulation, but is controlled directly. Any control deviations are thus ignored The speed is not readjusted.This manifests itself in increased driving comfort, because control oscillations of the speed are reliably avoided.The control valve unit 15 is controlled accordingly with a constant setpoint. From time t _u6 , the elevator car 1 should now be braked according to the a, v diagram The braking process begins at time t _U 6 with the linear structure of the brake deceleration, so that the acceleration a is increased from the value zero to a final value -a. This linear increase in the brake deceleration ends at the time t _u as with the change in acceleration between the times t _u2 and t ^ as well as t _u and t _u s, this change in acceleration results in a parabolic curve of the speed, so that the braking process now also begins very gently.This effect is caused by the fact that the setpoints PZSOIIL and P _Z SO _{IIB are} reduced, respectively from the Pz diagram and from the dPz / dt diagram According to these changing setpoints, the control valve unit 15 is 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.There} again applies that due to the changing, now decreasing flow rate, the flow resistances change, i.e. now decrease Accordingly, the setpoint for the pressure P _z , namely P _Z SOIIL or PZ _SOI IB, is slightly reduced from time t _u7 to time t _{u8 in} order to compensate for this change in flow resistance

In the period from time t _u8 to time t _U 9, the braking deceleration is now changed linearly towards zero. Accordingly, the setpoint value for the pressure P _z , that is to say P _ZSOIIL or P _ZSOIIB , is _reduced further, now at a lower speed, which can be deduced from the dPz / The dt diagram can be seen. Here, too, there is automatically a parabolic course of the speed, that is, a gentle braking until the elevator car 1 comes to a standstill

The specifications for the acceleration a, the speed v and the individual time segments from the time t _u2 to the time t “9 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 how to use magnetic or touch contacts when controlling the elevator car 1 Thus, 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 the time t "β, but only at the time t ^' _u β. Accordingly, the end of the linear increase in the delay shifts from the time t _u to the 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 _For the sake of clarity, the corresponding representation of the processes in the P _z diagram and in the dpz / dt diagram has been omitted

If the response of the corresponding shaft switching means coincides with the associated pre-calculated times tu _* , for example t _u6 , what _does that

Control unit 20 can recognize that the specified parameters are correct. If the response does not coincide, however, there is a need to correct the specified parameters. In this way, it is possible to adapt the parameters automatically. It is then not necessary to operate the elevator system, in short switch on a phase with so-called creep speed before reaching the desired destination.

If the control device 20 is designed to be self- _adapting accordingly, the definition of parameters during planning and commissioning of the elevator installation is considerably simplified. It should also be noted that, as can be seen from the H diagram after time t _u9 , the control valve unit 15 automatically returns to the closed position runs 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 the pressure in the pump line 8 in accordance with the curves P _PB and P _PL after the time t _u9 , as it is in the P _z - 3 shows the analog idealized diagrams for a downward journey. The type and structure of the four partial diagrams correspond to those of FIG. 2, but here no values are shown in the Pz 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 The respective load is determined by the load pressure sensor 18 (FIG. 1). In the a, v diagram, because of the reversed direction of travel, the curves are mirrored horizontally compared to FIG. 2, which means for FIGS. 2 and 3 that the a, v diagrams also show the vector of acceleration and speed The dPz / dt diagram again 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, the stroke of the valve spindle of the control valve unit 15 (FIG. 1) is not shown, in contrast to FIG. 2, but rather the stroke of the valve spindle of the control valve unit 5, which, as mentioned earlier who controls downward travel

The time axis t is again common to all four diagrams. Individual times tdo to td9 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 travel of the elevator car 1 will now be described below with the aid of these diagrams. At the time tdo, the start command for the upward travel is issued. The control unit 20 (FIG. 1) determines the current value of the load pressure sensor 18 at this time. The pump 10 (FIG. 1) does not become active during a downward travel switched on The run is not necessary because the drive is effected by the weight of the elevator car 1 during the downward travel. The proportional valve of the control valve unit 5 is still closed

During the period from tdo to tdi, the control device 20 in turn calculates the load _ratio P _ZOB P _ZOL or another corresponding reference quantity for the effective load that 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 values for acceleration a and speed v are achieved. This takes into account that when the elevator car 1 is empty, the control valve unit 5 must achieve a comparatively lower braking effect than when the elevator car 1 is loaded

In the period from the time tdi to the time td ₂ , the control valve unit 5 is now actuated in such a way that the differential pressure ΔP _dyn mentioned during the upward travel is compensated. This creates the conditions for the movement of the elevator car 1 to begin at the time t ₂ of 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. This means that hydraulic oil can flow from the lifting cylinder 3 through the control valve unit 5 in the direction of the tank 11. The now uncontrolled 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 via this check valve Regarding the tank 11, it should also be mentioned that the value of the differential pressure ΔP _dyn now 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 Control valve units 5 and 15 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 ΔPdyn for upward and downward travel are the same 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, a small part of the hydraulic oil can also flow back into the tank 11 through the pump line 8 and the stationary pump 10 because such pumps regularly have a leakage loss

For the subsequent period from time td ₂ to time td ₃ , the acceleration is increased from zero to a certain value. In order to achieve this linear increase in acceleration, the temporal drop in the cylinder pressure P _{z must be} constant, which is evident from the The dPz / dt diagram on the one hand and the P _z diagram on the other hand can be recognized. According to the linearly falling setpoint PZSOII _B for the loaded elevator car 1 or P _ZSOIIL for the empty elevator car 1, the regulation is now carried out by changing the control of the control valve unit 5 Da during the period From time td ₂ to time td the acceleration a rises from zero to the final value, there is a gentle start automatically, because the speed increases automatically at time t _d3 , the maximum acceleration is reached

During the subsequent period from time td ₃ to time td, this acceleration is maintained, so that the speed increases linearly during this time period. Here again, the pressure losses change due to the increasing flow rate. Since the pressure losses increase with increasing flow rate, the pressure must increase Setpoint for the cylinder pressure Pz slightly during this phase be reduced, which manifests itself in a corresponding change in the control of the valve control unit 5. As already mentioned during the upward journey, appropriate corrections must be taken into account in all phases of the movement of the elevator car 1

From the time td to the time tas, as can be seen from the a, v diagram, the acceleration a is reduced to zero again. This is achieved by the control unit 20 now _applying the pressure P _{z in} accordance with the setpoint _curves P _ZSOI IB or P _ZSOIIL To achieve this, the control of the control valve unit 5 is now changed so that it is only operated very slowly in the opening direction. Accordingly, a reversal of the pressure change can be seen from the dPz / dt diagram from the linear decrease in the acceleration there is then automatically a parabolic change in speed, i.e. a smooth transition to a different speed

From the time td5 to the time td Geschwindigkeit, the speed of the elevator car 1 remains constant according to the a, v diagram, the acceleration is therefore zero. Accordingly, the resistance also does not change anymore, from which it follows that the setpoint PZSOIIL or PZSOIIB remains constant, which is also the case The dPz / dt diagram can be seen in this area, therefore, the control valve unit 5 is regulated with a constant setpoint value, so that the stroke of the valve spindle of the control valve unit 5 changes only in the event of a control deviation. It is advantageous if in the period from the time tas up to the time t β

The control valve unit 5 is not controlled on the basis of a regulation, but is controlled directly. Any control deviations are therefore ignored.This means that the speed is not readjusted.This translates into increased driving comfort because control oscillations of the speed are reliably avoided.The control valve unit 5 is controlled accordingly with a constant setpoint

From time td ₆ , elevator car 1 should now be braked according to the a, v diagram. This braking process begins at time tdβ with the linear structure of the brake deceleration, so that acceleration a is increased from zero to a final value -a. This linear increase the braking deceleration ends at time t As mentioned for the change in acceleration between times t _d2 and td ₃ as well as td and td5, this change in acceleration results in a parabolic course of the speed, so that the braking process now also begins very gently Effect is brought _about by the fact that the setpoints P _ZSOIIL or P _{ZSOIIB are} increased, which can be seen from the P _z diagram and from the dPz / dt diagram. According to these changing setpoints, the control valve unit 5 is actuated in the closing direction from the time td the brake deceleration is no longer changed

Velocity is now reduced linearly.This is again evident from the a, v diagram.Here, the flow resistances also change due to the changing flow velocity, which is now decreasing.This means that the setpoint for the pressure P _z , namely PZSOIIL, becomes accordingly or P _ZSOIIB slightly increased from time t ₇ to time t _{8 in} order to compensate for this change in flow resistance

In the period from time td ₈ to time td9, the braking deceleration is now changed linearly towards zero. Accordingly, the setpoint for the pressure P _z , that is to say P _ZSOIIL or PZ _SOIIB , continues to increase, now at a higher speed, which is evident from the dPz / dt- Diagram is visible 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 td ₂ to the time t 9 are again selected such that the destination is exactly reached from the starting point of the elevator car 1. Nevertheless, it is advantageous to use the usual shaft switching means how to use magnetic or touch contacts when controlling the elevator car 1

In the sense of an example, it is also shown in FIG. 3 how, by means of such shaft switching means, the start of the delay is not triggered at the time tdβ, but only at the time t ^' dό. Accordingly, the end of the linear increase in the delay shifts from the time td ₇ at time t ^' d In this example, the shaft switching device is then waited for to respond. This causes braking somewhat later, which can be recognized 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 Pz diagram and in the dpz / dt diagram has been dispensed with. If the corresponding shaft switching devices are addressed with the associated ones

Times t _dx , for example t β, together, which the control device 20 can recognize, so the given 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, an adaptation can also take place during the downward travel.

In order to determine the target travel curves, the required time course of the pressure P _{z is} determined from the target values for the acceleration and the speed and is stored as a target value-time series in a target value transmitter of the control unit 20 as the target travel curve. The current actual value of the pressure Pz is determined with the aid of the load pressure sensor 18 and compared with the target value. The control command is generated from the difference between the actual value and the setpoint using standard control technology methods. 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 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 movement of the elevator car 1 is regulated by changing the actuation 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. Thus, only the load pressure sensor 18 is necessary both for the entire upward movement and for the entire downward movement in order to reliably regulate the movement of the elevator car 1. 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, and thus also in its pilot control chamber.

It can also be advantageous if there is no regulation with decreasing speed when driving upwards and downwards in the area of the target travel curve, but that when driving upwards the second control valve unit (15) and when driving downwards the first control valve unit (5) directly with a time-variable setpoint is controlled. As part of the adaptation, the setpoints and their change over time can be adjusted with the help of the switching elements arranged in the cabin shaft.

If necessary, in connection with the present invention

Creep speed should be switched on before stopping the elevator car if, due to special circumstances, the target position is not reached directly. The initiation and the end of the creep speed is triggered in a known manner by switching elements arranged in the cabin shaft.

Claims

1 Method for controlling a hydraulic elevator, the elevator car (1) of which can be moved by a hydraulic drive consisting of a reciprocating piston (2) and a lifting cylinder (3) by means of a pump (10) and with the participation of at least one control valve unit (5, 15) , namely for example a first control valve unit (5) and possibly a second control valve unit (15), hydraulic oil through a cylinder line (4) in the hydraulic drive (2, 3) or out of the hydraulic drive (2, 3) can be requested, the Flow of the hydraulic oil can be controlled by measuring means, the pressure in the cylinder line (4) can be detected by means of a load pressure sensor (18) and the function of the elevator can be controlled and regulated by a control device (20) executing the method, characterized in that

- 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) that detects the pressure Pz in the cylinder line (4), - that the upward travel of the elevator car (1) by changing the activation of the second control valve unit (15) is regulated in such a way that a target travel curve, which is dependent on the load on the elevator car (1) and represents a time course of the pressure in the cylinder line (4), with the continuous changes in the pressure in the cylinder line (4) is compared, the control command for the second control valve unit (15) being generated from the control deviation,

- 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 that is dependent on the load on the elevator car (1) and that shows a temporal 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 first control valve unit (5) being generated from the control deviation

2. The method according to claim 1, characterized in that no control takes place at upward and downward travel in the range of the target travel curve at constant speed, but that the second control valve unit (15) and upward travel the first control valve unit (5) directly with downward travel is controlled at a constant setpoint 3. The method according to claim 1 or 2, characterized in that during upward and downward travel in the area of the target driving curve with decreasing speed, there is no regulation, but that during upward travel the second control valve unit (15) and in downward travel the first control valve unit (5) is controlled directly with a time-variable setpoint

4. The method as claimed in one of claims 1 to 3, characterized in that the change in pressure Pz over time is evaluated by the control device (20) by determining the acceleration acting on the elevator car (1) from the size and gradient of this change in time

5 The method according to claim 4, characterized in that the speed of the elevator car (1) is determined by integrating the acceleration

6. The method as claimed in claim 5, characterized in that the distance covered by the elevator car (1) is determined by integrating the speed

7. The method according to any one of claims 1 to 6, characterized in that the pressure P _P generated by the pump (10) and influenced by the second control valve unit (15) in the pump line (8) is determined by means of a pump pressure sensor (23) that the pressure in the pump line (8) is measurable and thus the stepwise or continuous change in the pressure rise can also be regulated if necessary

8. The method as claimed in claim 7, characterized in that in the control device (20) the difference between the pressure P _z determined by the load pressure sensor (18) and that of the

Pump pressure sensor (23) determined pressure P is formed and that this difference is used to determine the flow of hydraulic oil in the cylinder line (4)

9. The method according to claim 7, characterized in that the pump pressure sensor (23) is designed as a differential pressure sensor which determines a differential pressure P _{D which} determines the difference between the pressure P _z prevailing in the cylinder line (4) and the pressure in the pump line (8). prevailing pressure P _P corresponds

10. The method according to any one of claims 1 to 9, characterized in that by means of a temperature sensor (21) arranged on the first control valve unit (5) Temperature of the hydraulic oil is determined and taken into account by the control device (20) when controlling the elevator

11 Device for controlling a hydraulic elevator, the elevator car (1) of which can be moved by a hydraulic drive consisting of a reciprocating piston (2) and a lifting cylinder (3) by means of a pump (10) hydraulic oil from a tank (11) through a pump line ( 8) to at least one control valve unit (5, 15) and from this through a cylinder line (4), in which the pressure can be measured by means of a load pressure sensor (18), can be conveyed to the hydraulic drive, with at least one of the control valve units (5 , 15) the flow rate of the hydraulic oil can be controlled and controlled by measuring means, and in which the pump (10) and at least one of the control valve units (5, 15) can be controlled by a control device (20), characterized in that

- that the control device (20) controls a first control valve unit (5) and / or a second control valve unit (15), - that the control device (20) contains setpoint travel curves for the upward and downward travel in a setpoint generator, wherein each target travel curve represents a time course of the pressure Pz in the cylinder line (4),

- That the control device (20) compares the respective actual values of the pressure Pz with the nominal values during the upward and downward travel and, in accordance with the control deviation during the upward travel, the second control valve unit (5) and

Downward drives the first control valve unit (15), and

- That the control device (20) does not control the pump (10) when the elevator car (1) is to move in the downward direction

12 Device according to claim 11, characterized in that a pump pressure sensor (23) is present as measuring means, which detects the pressure P _P in the pump line (8),

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

- And that the control device (20) is such that it can generate additional data from the signal of the load pressure sensor (18) through which the pressure P _{P can be} controlled by the control device (20) under control of the second control valve unit (15)