EP0643006A1 - Method and system for controlling a hydraulic lift - Google Patents

Abstract

With this method, accurate direct arrival at a floor can be achieved without travel at creep speed being necessary. Here, the car is controlled as a function of displacement in the deceleration phase, for which purpose a control range (CS) is formed which is divided into percentage values. The percentage values are put into tabular form in relationship to measured actual displacement values. When a certain actual displacement value occurs, the corresponding percentage value is multiplied by the value of the control range (CS) and if need be a control deviation (CO) and a pilot-control signal (SO) are added to the product, the sum forming the actual control signal (S) used in each case during the deceleration phase, which control signal (S) is fed to a control-valve arrangement. <IMAGE>

Description

The invention relates to a method and a device for controlling a hydraulic elevator, wherein a control device generates control signals which are fed to a control valve arrangement which regulates the flow of a hydraulic fluid in such a way that a cabin of the elevator accelerates, moves at a constant speed, and when one arrives Braking point signaling shaft information is delayed.

In such elevators, the driving speed depends more or less on changes in the car load and the temperature of the hydraulic hydraulic fluid, which means that the flow controlled by a control valve changes accordingly and an exact entry on one floor is not possible. In order to remedy this deficiency, a switch is made to a small, constant creeping speed shortly before reaching the floor, so that differences in height of the stopping point caused by changes in load and / or temperature can be compensated for (FIG. 3). This leads to an increase in driving and waiting times for the users and requires high energy consumption. In the case of hydraulic elevators, the length of the creep speed is also known to depend on the load and temperature conditions.

German patent 36 38 247 discloses a device for a hydraulic elevator with which the above-mentioned disadvantages are to be remedied. A control device is provided that determines the speed behavior of the cabin Output signals generated, which are fed to a control valve. The control valve supplies the hydraulic fluid originating from a hydraulic fluid source in accordance with the output signals to a hydraulic cylinder driving the cabin or vice versa. In a memory connected to the control device via a computing unit, reference speed values are stored which correspond to specific operating states which relate to different load and / or temperature conditions. A measuring sensor arranged on the cabin detects the actual speed and feeds it to the computing unit via a converter unit. In this case, a difference is formed from the actual speed measured during the acceleration phase and a predetermined reference speed, on the basis of which the computing unit calculates a control speed curve. This control speed curve is stored and used during the deceleration phase to correct the actual speed to the value of the predetermined reference speed. In this way, an accurate and fast control of the destination should be made possible and thus the operating time of the elevator should be shortened. The control device, which has no control loop and no regulation for adapting the time at which the brake is used, however, does not manage without creeping speed.

The invention has for its object to propose a method and a device for performing the method according to the preamble of claim 1, which enables direct entry on a floor without travel at creep speed.

This object is achieved by the invention characterized in claims 1 and 8. In the deceleration phase, the cabin is controlled depending on the route, for which purpose a travel-specific control area is formed, which is divided into percentage values. The percentage values are set in tabular form in relation to measured actual path values. When a certain actual travel value arrives, the corresponding percentage value is multiplied by the value of the control area and the current control signal used during the deceleration phase is formed from it. This is fed to a control valve arrangement.

The advantages achieved with the invention can be seen in the fact that driving and waiting times are reduced, the hydraulic fluid heats up less and the energy consumption decreases. Due to the proposed direct entry using a control valve arrangement with a position feedback that is simple in structure, an exact stop without level adjustment is achieved and an optimal deceleration result is achieved in terms of driving comfort and minimal driving time. Load and temperature changes have no influence on the holding accuracy. It is also advantageous that the acceleration of the cabin and the travel at nominal speed can take place without control, which has a favorable effect on the efficiency of the hydraulic drive. Another advantage can be seen in the fact that the use of the control valve arrangement which interacts with a control device enables the automatic determination of elevator-specific parameters by means of a learning trip. This eliminates the need for manual adjustment work when starting up the elevator.

Fig. 1

eine schematische Darstellung der erfindungsgemässen Einrichtung,

Fig. 2

eine schematische Darstellung einer Regelventilanordnung der Einrichtung gemäss Fig. 1,

Fig. 3

ein Geschwindigkeits/Zeit-Diagramm eines hydraulischen Aufzuges gemäss Stand der Technik,

Fig. 4

ein Geschwindigkeits/Zeit-Diagramm und ein Steuersignal/Zeit-Diagramm eines mit der erfindungsgemässen Einrichtung gesteuerten hydraulischen Aufzuges, und

Fig. 5

ein Blockschaltbild eines Wegreglers der Einrichtung gemäss Fig. 1.

Advantageous further developments and improvements are possible through the measures listed in the dependent claims. The invention is explained in more detail below with reference to an embodiment shown in the drawing.
Show it:

Fig. 1

2 shows a schematic representation of the device according to the invention,

Fig. 2

1 shows a schematic illustration of a control valve arrangement of the device according to FIG. 1,

Fig. 3

a speed / time diagram of a hydraulic elevator according to the prior art,

Fig. 4

a speed / time diagram and a control signal / time diagram of a hydraulic elevator controlled by the device according to the invention, and

Fig. 5

2 shows a block diagram of a position controller of the device according to FIG. 1.

In Fig. 1, 1 denotes a cabin which can be set in motion by means of a hydraulic lifting device 2 having a piston 3 and a cylinder 4. The movement is transmitted by means of a rope 5 which runs over two rollers 6 attached to the piston 3, two rollers 7 attached to the cabin 1 and a stationary roller 8, the cabin 1 being guided in a shaft 9. A shaft switch 10 arranged in the shaft 9, a sensor 11 connected to the cabin 1 and a command control 12 are connected to a preferably digital control device 20. The sensor 11 has a wheel that rolls on a rope stretched along the shaft 9 and emits path signals in the form of pulse signals. The sensor 11 can work as described or in another way mechanically, but also electrically or optically. A control valve arrangement 13 described in more detail below with reference to FIG. 2 is electrically connected to the output of the control device 20 and is connected to the hydraulic lifting device 2 and a pressure fluid source 14 via hydraulic fluid lines.

The command control 12 feeds the control device 20 driving commands. Brake application signals are supplied to it by a control unit 21, which is part of the control device 20. The brake application signals come from the shaft switches 10, which are attached at certain intervals in front of the floors. Brake application signals can also be derived from the sensor 11, for example by generating corresponding shaft information when there are a certain number of summed-up travel signals. The control device 20 generates a signal S which is fed to the control valve arrangement 13.

The control unit 21 is connected to a tachometer signal converter 22, which converts the distance signals supplied by the sensor 11 into actual speed values vi or actual position values si. A speed controller 23 is connected on the input side to an output of the tacho signal converter 22 which outputs the actual speed values vi and to a speed setpoint vs output of a speed setpoint generator 24 which is connected on the input side to the control unit 21. The speed controller 23 can be reset or started via a further input connected to the control unit 21. A conventional PID controller can be used for the speed controller 23. 25 denotes a travel controller described in more detail below with reference to FIG. 5, which is connected on the input side to the control unit 21 and to an output of the speed signal converter 22 which outputs the actual travel values si. A path 26 belongs to the path controller 25, in which assignments of actual path values si to percentage values% S of a control area CS described later with reference to FIG. 4 are stored. A switching device 27 is connected to an output of the control unit 21, the output of the speed controller 23, the output of the travel controller 25 and the input of a DA converter 28. The output can be switched by means of the switching device 27 of the travel controller 25 are switched to the input of the DA converter 28 when a shaft information signaling the braking application point arrives. The output of the DA converter is connected to an amplifier 29, the output of which forms the output of the control device 20.

The control valve arrangement 13 shown in FIG. 2 has two similar electro-hydraulic throttle valves 30, 30 '. The following description for the throttle valve 30 for controlling the lowering process applies in the same way to the throttle valve 30 'for lifting the cabin, which is shown in mirror image, in which the same reference numbers, but with a tick, are used.

A main piston 32 is guided in a valve chamber 31, from which a piston rod 33 protrudes at the rear. A pilot valve 34 with an electromagnet 35, which is electrically connected to the output of the control device 20 (FIG. 1), is arranged around it without a functional connection. The piston rod 33 protrudes from the rear of the pilot valve 34 and carries a stop 36 at its end, a compression spring 37 being arranged between the stop 36 and the pilot valve 34. The compression spring 37 counteracts the force of the electromagnet 35. A closed control loop with internal feedback is produced in the pilot valve 34 by means of the compression spring 37. The pilot valve is arranged in a connecting line 38 and regulates its flow. The connecting line 38 connects a front chamber 39 and a rear chamber 40 of the valve chamber 31 to one another.

The front chamber 39 has an inlet C which is connected via a variable passage 39.1 to an outlet T which opens into a tank 42. The inlet C is connected to the cylinder 4 of the lifting device 2. The rear chamber 40 is also connected to the tank 42 via a drain line 41. An electromagnetic closing valve 44 is located in the drain line 41.

The control valve arrangement works with a lifting force feedback, i.e. the force of the compression spring 37, which represents the position of the main piston 32, is measured and serves as a feedback signal. It is thereby achieved that the force of the electromagnet 35 or the strength of the control signal S is proportional to the position of the main piston 32. This solution has good dynamic behavior and is inexpensive and simple to set up. However, other, for example hydraulic, electrical or mechanical, returns can also be used.

In the throttle valve 30 ', the outlet T' of the front chamber 39 'is also connected to the tank 42. An inlet labeled P is connected to a motor-driven pump 45 of the pressure fluid source 14. The pump 45 draws in from the tank 42. The throttle valve 30 'does not require a closing valve in its drain line 41'.

Inlets C and P are connected to one another via a connecting line 47 with a check valve 48. The check valve 48 acts in such a way that the hydraulic fluid cannot flow back from the lifting device 2 in the direction of the pump 45.

When the cabin 1 is at a standstill, the signal S is zero and the throttle valve 30 is closed (hydraulically). This is achieved by a slightly open pilot valve 34, so that the valve chambers 39 and 40 are connected to one another and the pressure acting in the rear chamber 40 on the large rear surface of the main piston 32 displaces it in the direction of the chamber 39. The closing valve 44 is closed when the cabin 1 is at a standstill and upwards. The throttle valve 30 'is open when the cabin 1 is at a standstill.

If there is a call for downward travel, the control device 20 generates a signal S which corresponds to a closed position of the throttle valve 30, ie that Pilot valve 34 is opened to such an extent that its opening cross-section is larger than that of the discharge line 41. When the closing valve 44 is subsequently opened, the main piston 32 remains in its closed position despite the pressure medium discharge through the line 41. Thereafter, the electromagnet 35 receives a signal S 'which is inversely proportional to the signal S and which in principle does the following: The force of the electromagnet 35 works counter to the force of the compression spring 37. When the main piston 32 is displaced so far by pressure differences in the chambers 39, 40, that the flow through the connecting line 38 is the same as that in the drain line 41, the main piston 32 stops and remains in this position until the control signal S is changed.

When the signal S increases, that is, the signal S ′ decreases, the opening cross section of the pilot valve 34 also decreases and the main piston 32 is withdrawn due to the lower pressure in the rear chamber 40. The passage 39.1 is now open and the pressure medium flows from the lifting device 2 into the tank 42, as a result of which the cabin 1 lowers. The signal S is increased until the cabin 1 reaches the desired maximum speed. The signal S remains at this level until the brake application signal occurs. From then on, the signal S is reduced again depending on the path away from the control device 20, as a result of which the main piston 32 moves in the direction of the passage 39 until it closes it completely in order to bring the cabin to a standstill. At this moment, the closing valve 44 is also closed. The throttle valve 30 'remains open unchanged during the downward travel.

The throttle valve 32 'for lifting the cabin 1 works in principle the same as the throttle valve 32, but with the difference that the signal S' for the electromagnet 35 'is proportional to the signal S. If a call is made to Upward travel, the pump 45 is switched on and the pressure fluid pumps into the chamber 39 'and through the valve gap 39.1' into the tank 42. The pilot valve 34 'then receives a signal S', which leads to the opening of the connecting line 38 '. Thereupon, pressure medium flows from the front chamber 39 'to the rear chamber 40'. With a certain amount of the signal S, the opening cross section of the pilot valve 34 'becomes larger than the cross section of the drain line 41'. This increases the pressure in the rear chamber 40 'and the main piston 32' moves forward and narrows the valve gap 39.1 '. As soon as the pressure in the chamber 39 'exceeds the pressure in the lifting device 2, the check valve 48 opens and the cabin 1 starts to move. When the valve gap 39.1 'is completely closed, the elevator moves upwards at maximum speed.

The acceleration process and driving at nominal or operating speed can take place without control. When driving upwards, the full, unthrottled power of the pump 45 can be used. The maximum speed of the cabin 1 is then determined by the pump output. The speed of the descent can be limited by an appropriately dimensioned aperture in the drain line of the lifting device 2.

In the exemplary embodiment shown, two pilot valve arrangements are provided, only one being active in each direction of travel. In a further embodiment variant, only one pilot valve arrangement is provided for both directions of travel, which alternately controls both throttle valves 30, 30 '.

In FIG. 3 representing the prior art, v denotes the speed and t the time. Depending on the load and temperature of the hydraulic fluid, different speed / time characteristics result during the deceleration phase A, B, so that a creep speed C is required for an exact entry.

S0, S1, S2

bestimmte Werte des Steuersignales S,

CS

einen Steuerungsbereich,

H

einen Hysteresewert und

CO

eine Steuerabweichung.

According to FIG. 4, speed and time are again designated by v and t, the v-axis also being associated with the control signal S generated by the control device 20. A characteristic curve D represents the actual speed curve, while a characteristic curve E represents the curve of the control signal S at the output of the control device 20 while the cabin 1 is traveling. Also mean:

S0, S1, S2

certain values of the control signal S,

CS

a control area,

H

a hysteresis value and

CO

a tax variance.

According to FIG. 5, the table 26, by means of which control signals for the control valve arrangement 13 associated with the actual travel values si are formed during the deceleration phase, is connected to the input of a multiplier 25.1, each of which has a percentage value% S of the control area corresponding to the current actual travel value si ' multiplied by the calculated value of the control area CS. To improve the control result, the output of the multiplier 25.1 is connected to the input of an adder 25.2, which adds the control deviation CO and the pilot control signal S0 to the product of the multiplier 25.1 and whose output forms the output of the position controller 25.

(Fig. 4) errechnet, wobei S1 und S2 der erste und zweite Wert des Steuersignales S sind und H ein Hysteresewert ist, der wie nachstehend näher beschrieben ermittelt wird. Der Wegregler 25 arbeitet nun in der Weise, dass wie bereits anhand der Fig. 5 beschrieben, die den Wegistwerten si entsprechenden prozentualen Werte %S mit dem errechneten Wert des Steuerbereiches CS multipliziert werden und die Steuerabweichung CO und das Vorsteuersignal S0 dazu addiert wird, wobei $\text{CO = S2 - S0 - CS}$

ist (Fig. 4). Die so ermittelte Summe wird über die Schalteinrichtung 27 und den DA-Wandler 28 dem Verstärker 29 zugeführt (Fig. 1), an dessen Ausgang sie als das jeweils aktuelle Steuersignal S auftritt.The control device 20 described above operates as follows. When a drive command from command control 12 arrives, speed controller 23 is reset or activated by control unit 21, and the input of DA converter 28 is switched to the output of speed controller 23 by switching device 27. The cabin 1 is now during the acceleration phase and driving at constant speed by comparing the actual speed values vi controlled with the speed setpoints vs, the control signal S at the output of the control device 20 running according to the characteristic curve E (FIG. 4). After the arrival of a driving command, the cabin 1 starts to move at the start time t1 and at the same time a first value S1 of the control signal S is stored (FIG. 4). If the cabin 1 reaches a braking point of application, the relevant shaft switch 10 or the sensor 11 sends a shaft information to the control unit 21, whereupon the delay phase is initiated. Here, the path controller 25 is activated and its output is switched to the input of the DA converter 28 by means of the switching device 27. At the same time, a second value S2 of the control signal S is stored and a control area CS according to the relationship $\text{CS = S2 - S1 + H}$

(FIG. 4), where S1 and S2 are the first and second values of the control signal S and H is a hysteresis value which is determined as described in more detail below. The displacement controller 25 now works in such a way that, as already described with reference to FIG. 5, the percentage values% S corresponding to the displacement actual values si are multiplied by the calculated value of the control range CS and the control deviation CO and the pilot control signal S0 are added, whereby $\text{CO = S2 - S0 - CS}$

is (Fig. 4). The sum determined in this way is fed via the switching device 27 and the DA converter 28 to the amplifier 29 (FIG. 1), at the output of which it appears as the respectively current control signal S.

As already mentioned in the description of FIG. 2, in the selected control valve arrangement 13 the position of the main piston 32 is exactly proportional to the control signal S. The control signal S generated by the speed controller 23 is dependent on the load and temperature up to the point in time at which the brake is used. However, since the control area CS for the deceleration phase is redefined based on the values S1, S2, H for the current load and temperature conditions that are constant during a journey, an accurate one can be Direct entry can be achieved without the need to adjust the level.

The hysteresis value H is determined as follows during a learning trip: The control signal S is increased until the speed reaches a predetermined value. When the predetermined value is reached, the strength of the control signal S is measured and stored. The control signal S is then increased further and decreased again after a while until the predetermined value of the speed is reached again. The strength of the control signal S is then measured again and a difference is formed from the two measured values, which represents the hysteresis value H.

Further elevator-specific parameters related to direct entry, such as a pilot control signal S0 or a limit control signal SL, are also determined during a learn run:

Pilot control signal S0:

On the one hand, the pilot control signal S0 causes the elevator car to exit immediately after the start command, on the other hand, the starting control jerk can be significantly reduced with the pilot control signal S0. To determine the pilot control signal S0, the electromagnet 35 of the control valve arrangement is subjected to a step-by-step increasing control signal S until the elevator car starts moving. The control signal determined in this way is reduced by a constant value and stored as pilot control signal S0. When a travel command arrives, the control valve arrangement 13 is acted upon directly by the pilot control signal S0.

Limit control signal SL:

The limit control signal SL is the control signal S at which the main piston 32 of the control valve arrangement 13 reaches its end position. The control device 20 operates in such a way that the value of the control signal S is the value of the Limit control signal SL can never exceed. As explained above, a hydraulic elevator is usually operated in a speed-controlled manner. With the limit control signal SL determined during a learning trip, uncontrolled operation during constant travel and position-controlled operation during the subsequent deceleration phase are feasible.

In the case of speed-controlled operation, part of the hydraulic fluid conveyed by the hydraulic fluid source 14 is returned to the tank 42 by means of an overflow line. In the case of uncontrolled operation, the control valve arrangement 13 is acted upon by the limit control signal SL, so that the entire delivery capacity of the pressure fluid source 14 is effective in the lifting device 2, as a result of which the efficiency of the lifting device 2 is significantly improved. The transition from uncontrolled constant travel to position-controlled deceleration travel takes place without a control delay, because the value of the limit control signal SL, even in the case of previous uncontrolled operation, is such that the main piston 32 can immediately follow the limit control signal SL. In order to determine the limit control signal SL, the coil of the control valve arrangement is subjected to a step-by-step control signal S until the speed of the elevator car no longer increases. The control signal determined in this way is stored by the control device 20 as a limit control signal SL.

The device according to the invention can preferably be implemented by means of a microcomputer system.

Claims (10)

Method for controlling a hydraulic elevator, wherein a control device (20) generates control signals (S) with the aid of a sensor (11) connected to a cabin (1) of the elevator, which control signals (S) are fed to a control valve arrangement (13) which controls the flow of a Controls hydraulic fluid in such a way that the cabin (1) accelerates in the downward or upward direction, moves at operating speed and is decelerated when a shaft information signaling the brake application point arrives, characterized in that
that the sensor (11) picks up travel signals and the car (1) is controlled depending on the travel in the deceleration phase, with a first value (S1) of the control signal (S) being determined and stored at the start time of the car 1 after the entry of a travel command,
when the brake application signal arrives, a second value (S2) of the control signal (S) of the control device (20) is stored,
a control area (CS) according to the relationship $\text{CS = S2 - S1 + H}$

is formed, where S1 is the first value of the control signal, S2 is the second value of the control signal and H is a previously determined hysteresis value,
actual position values (si) are generated from the distance signals during the deceleration phase
a percentage value (% S) of the control area (CS) is assigned to each actual path value (si),
the percentage values (% S) are multiplied by the value of the control area (CS) and
the product determined in this way determines the size of the control signal (S) used during the delay phase. A method according to claim 1, characterized in that a signal representing the position of the main piston (32 or 32 '), which is preferably at one of the Piston rod (33 or 33 ') coupled spring (37 or 37') is tapped, serves as a feedback signal. A method according to claim 1, characterized in that a control deviation (CO) and a pilot control signal (S0) are added to the product determining the control signal, wherein CO according to the relationship $\text{CO = S2 - S0 - CS}$

is found, and where S2 is the second value of the control signal, S0 is the pilot signal and CS is the control area, and the sum thus determined represents the control signal (S) used during the delay phase. Method according to one of the preceding claims, characterized in that the hysteresis value (H) is determined during a learning trip, the control signal (S) being increased until the speed reaches a predetermined value, and when the predetermined value is reached, the strength of the control signal (S ) is measured and stored, then the control signal (S) is further increased and after a while it is reduced again until the specified value of the speed is reached again, the strength of the control signal (S) is measured again and a difference from the two measured values is formed, which represents the hysteresis value (H). A method according to claim 3, characterized in that the pilot signal (S0) is determined during a learning trip, wherein the coil of the control valve arrangement (13) is acted upon with a step-wise increasing control signal (S) until the cabin (1) starts moving and the the control signal determined is reduced by a constant value and stored as a pilot signal (S0). Method according to one of the preceding claims, characterized in that a limit control signal (SL) is determined during a learn run, the coil of the control valve arrangement (13) being provided with a step-by-step process increasing control signal (S) is applied until the speed of the cabin (1) no longer increases. Method according to one of claims 1 to 5, characterized in that the cabin (1) is driven in an uncontrolled manner during the journey preceding the deceleration phase, the speed being increased by the design of hydraulic components, such as e.g. a pump (45) is limited. Device for carrying out the method according to claims 1 to 7, with a control device (20) which controls a control valve arrangement (13) and with a sensor (11) connected to the cabin (1),
characterized in that the control device (20) has at least one tacho signal converter (22), the sensor (11) being connected to the input of the tacho signal converter (22), that the control device (20) further has a path controller (25) which is connected on the input side is connected to an output of the tacho signal converter (22) which outputs actual values (si) and is connected to the control valve arrangement (13) on the output side during the deceleration phase that the position controller (25) has a table (26) in which assignments of actual position values (si) Percentage values (% S) of a control area (CS) are stored, that a multiplier (25.1) is provided, one input of which is connected to the table (26), while the other input is supplied with the value of the control area (CS) and the output of which forms the output of the travel controller (25). Device according to claim 8, characterized in that the control valve arrangement (13) has a lifting force feedback preferably generated by means of a compression spring (37, 37 '). Device according to claim 8, characterized by a control device (20) with a digital path controller (25).

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