EP0915804B1 - Method and device for controlling a hydraulic lift - Google Patents

Abstract

The invention concerns a method and device for controlling a hydraulic lift, wherein a lift car (2) can be moved upwards and downwards in a lift shaft (1). The lift car (2) is connected to a reciprocating piston and is driven by an oil pump (40) which delivers pressurized oil between a tank (41) and a lifting cylinder (3). The oil pump (40) is driven by a motor (39) which is fed by a controllable power-supply part (28). The speed of the lift car (2) is detected by a sensor (13). A control and regulating unit (10) controls and regulates the assemblies influencing the movement of the lift car (2), that is the motor (39) and a valve unit (43). During upwards travel, the speed of the lift car (2) is controlled by regulating the motor (39). According to the invention, during downwards travel, a regulating and controlling effect is exerted on the valve unit (43). At low speeds when the lift car (2) is starting to move or braking, the speed is regulated by actuating the valve unit (43); at faster speeds, such as during upwards travel, the speed is regulated by regulating the motor (39).

Description

The invention relates to a method for controlling a hydraulic elevator according to the preamble of claim 1 and to a device for performing the Method according to the preamble of claim 5.

Such controls are suitable, for example, for operating a lift system in which one Cab in an elevator shaft different positions, e.g. different floors one Building. The cab is driven by the interaction a reciprocating piston connected to the cabin with a lifting cylinder, which with a pressure oil is filled. The lifting cylinder is connected to a pump via a cylinder line is driven by a motor. By rotating the motor and the pump in one Direction of pressure oil can be conveyed from an oil tank to the lifting cylinder, causing the cabin to move in Moving upwards. By rotating the motor and the pump in the opposite direction, pressure oil is pumped from the lifting cylinder into the oil tank, causing the cabin is moved downwards. This is due to the weight of the cabin Pressurized oil in the lifting cylinder and in the cylinder line constantly under a certain pressure.

To control the movement, it is known, for example, from US-A-5,243,154, a rigid one to control the motor coupled with the pump with regard to direction of rotation and speed. Known is also, when descending, the dead weight of the cabin and the resulting Use pressure to drive the pump. As a result of the rigid coupling to the engine the motor acts as a generator, whereby the energy generated during the downward movement either converted into heat or through a regenerative unit in the Power grid can be fed. In addition, between the lifting cylinder and the pump, a valve unit with which the flow of pressure oil between Lift cylinder and pump can also be affected.

There is a leak in the pumps commonly used for the stated purpose inevitable. The leakage is a function of the prevailing pressure. That has to Consequence that the pump speed must be slightly higher than it should be when driving upwards if there was no leakage. It also follows that when the cabin is in one the pump should run at a certain speed in order to pump such a large amount of pressure oil that this leakage is just compensated for becomes. This is known for example from US-A-4,593,792.

From US-A-5,212,951 a generic hydraulic elevator system is known in which the Control of the movement of the cabin with a motor acting on the pump variable speed. With the help of an electrically controlled check valve the pressure on the side facing the pump before the cabin begins to move first adjusted to the pressure on the side of the lifting cylinder facing the Check valve prevails. The check valve only opens after this pressure adjustment, see above that the movement of the cabin begins. With this measure, jerky movements largely avoided when starting.

From GB-A-2 243 927 a hydraulic elevator system is known in which a electromagnetic control valve is present. The movement of the cabin also begins here only when the pump pressure exceeds the lifting cylinder pressure. Only after this Pressure adjustment, the control valve switches the connection from the pump to the lifting cylinder by.

A method and a device for control a hydraulic elevator according to the preamble of Claims 1 and 5 are also from the document US-A-5 040 639 known.

All known solutions with speed-controlled motors have the problem in common that the motors have a certain speed compliance, which is also referred to as slip becomes. The lowest possible rotational speed with full torque, which is operationally trouble-free, is one Function of this slip. This is below a limit speed caused by this Rotational behavior of the motor is unstable, which manifests itself in fluctuations in speed.

The object of the invention is to provide a solution based on these circumstances Takes into account when operating at very low speeds such as the Transition to a standstill enables a smooth ride. At the same time, the hydraulic Elevator or its control system get along with few sensors and use Allow standard electrical components for motor control.

The stated object is achieved according to the invention by the features of claims 1 and 5 solved. The claim 1 relates to the inventive method, during the Claim 5 identifies a device with which the inventive method can be carried out. Advantageous further developments result from the dependent ones Claims.

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

Fig. 1

ein Schema einer hydraulischen Aufzugsanlage mit einer ihrer Steuerung dienenden Vorrichtung,

Fig. 2

einen Teilschnitt eines Steuerventils,

Fig. 2a und 2b

Details eines Schnittes und

Fig. 3 bis 6

Signaldiagramine zur Erläuterung der Funktion.

Show it:

Fig. 1

a diagram of a hydraulic elevator system with a device serving to control it,

Fig. 2

a partial section of a control valve,

2a and 2b

Details of a cut and

3 to 6

Signal diagram to explain the function.

1 shows an elevator shaft 1 in which a rail-guided car 2 is movable. The cabin 2 is connected to a lifting piston of a lifting cylinder 3. in the Elevator shaft 1, shaft pulse generator 4 are arranged, which in cooperation with the Cabin 2 attached, not shown in Fig. 1 actuators Enter information about the position changes, for example the approach to Floor from above or from below.

FIG. 1 also shows an elevator control 5, which has a signal line 6 with external control units 7, which are assigned to the individual floors and of which in FIG. 1 only one is shown, and a cabin control unit 8 is connected. In the Elevator control 5 can be, for example, a commercially available product such as the Act "Liftronic 2000 elevator control" (Findili AG, Kleinandelfingen / Switzerland). A control line 9 leads from the elevator control 5 to a control and regulating unit 10. On this control line 9 5 control command signals K from the elevator control the control unit 10 transmits what will be described later.

The control command signals K pass from the elevator control 5 to a control input 11 of the control and regulating unit 10. From this control input 11, these control command signals K are fed to a setpoint generator 12. 1 shows a flow meter 13 with which the flow of the pressure oil from and to the lifting cylinder 3 and thus clearly also the speed of the cabin 2 are detected. This flow meter 13 is connected via a signal line 14 to a further input 15 of the control and regulation unit 10, so that measured values of the volume flow, namely its actual values x _i , from the flow meter 13 are available to the control and regulation unit 10. The flow meter 13 can advantageously contain a Hall sensor. Such a flow meter is known from EP-B1-0 427 102.

The setpoint generator 12 uses the control command signals K to generate a setpoint x _s for the speed of the cabin 2. Because of the clear relationship between the cabin speed and the volume flow of the pressure oil, measured with the flow meter 13, this setpoint for the cabin speed is at the same time the setpoint x _{s of} the volume flow. These two values, actual volume flow value x _i and desired volume flow value x _s , which can therefore also be referred to as actual cabin speed value x _i and desired cabin speed value x _s , are fed to a controller 18, which in a known manner produces a control deviation Δx and a manipulated variable y is determined from this. This manipulated variable y is available at a first output of the controller 18.

The setpoint generator 12 also generates directly from the control command signals K. also target values for the units to be controlled by the control unit 10, which will be described later.

All setpoints and also the control command signals K are sent to a control block 19 fed. This control block 19 has three outputs: a first output leads to a first signal converter 22, the output of which is contained in the elevator control 5 Safety relay 23 is guided on a valve drive 24. This valve drive 24 can advantageously have a magnetically acting drive, for example one Proportional solenoid. A second output of the control block 19 leads to a second Signal converter 27, the output of which is connected to a power supply part 28. This Power supply part 28 contains a power controller 29, for example a Frequency converter. A third output of the control block 19 is with a third Signal converter 30 connected, the output of which is also connected to the power supply part 28 connected is.

In Fig. 1, a control block 33 is also shown, which from a second output of the Controller 18 receives the information about the size of the control deviation Δx. This Control block 33 compares the size of the control deviation Δx with a limit value and triggers then, when the size of the control deviation Δx exceeds this limit value, which is fed to the control block 19. So that are all starting from the control block 19 Signals can be set to zero so that the cabin 2 comes to a standstill in an emergency.

For the sake of completeness, a parameter block 34 is also shown, which has a serial Interface 35 is connected. One is not shown via this serial interface 35 Service unit can be connected to the control unit 10. That way you can Parameters of the control and regulating unit 10 such as the aforementioned limit of Control deviation Δx can be queried and changed

Fig. 1 further shows a in the illustrated embodiment as a three-pole line Power line 36 shown, which is connected to the main switch 37 with the Power supply network L1, L2, L3 is connected. By means of this power line 36 is the Power supply part 28, the electrical energy required to operate the hydraulic elevator fed. The electrical energy is supplied from the power supply part 28 via a Motor contactor 38, which can consist, for example, of two contactors connected in series, fed to a motor 39. According to the representation in FIG. 1, the Power supply network L1, L2, L3 around a three-phase network and the motor 39 is corresponding a three-phase motor. However, the invention is not so limited. For example the motor 39 can be any electric motor, also a direct current motor. The The design of the power supply part 28 corresponds in each case to the motor 39 used.

The engine 39 is rigidly connected to an oil pump 40, with which pressure oil from an oil tank 41 is conveyable in the lifting cylinder 3. Usually, the motor 39 and the oil pump 40 are immediate arranged in this oil tank 41. The pressure oil delivered by the oil pump 40 passes over a pump line 42 to a valve unit 43 and from there via a cylinder line 44 to the lifting cylinder 3. The direction of rotation of the motor 39 determines the flow direction of the Pressure oil. In one direction of rotation, pressure oil passes from the tank 41 via the pump line 42, Valve unit 43 and cylinder line 44 to the lifting cylinder 3, provided the speed of the engine 39 the speed that is necessary to compensate for the leakage of the oil pump 40 is greater. As a result, the cabin 2 is moved in the upward direction. Arrived in the other direction Pressure oil from the lifting cylinder 3 via cylinder line 44, valve unit 43 and pump line 42 in the oil tank 41. This moves the cabin 2 in the downward direction

It can also be seen from FIG. 1 that the power supply part 28 is connected via a line 45 to a status input 46 of the control and regulating unit 10. Status signals S _St arrive on line 45 from power supply part 28 to control and regulating unit 10.

The valve unit 43 advantageously consists essentially of a check valve 47 and a down valve 48 that is between the pump line 42 and the cylinder line 44 are arranged parallel to each other. The down valve 48 in turn advantageously consists of a control valve 49 and a pilot valve 50 acting thereon, the Pilot valve 50 is advantageously actuated by the valve drive 24 already mentioned.

In order to meet the safety requirements, valve unit 43 is also contain an emergency drain valve 51, which on the side facing the cylinder line 44 Connection of check valve 47 and down valve 48 is arranged. Is also on the the pump line 42 facing side of the connection of check valve 47 and Down valve 48 a pressure relief valve 52 is arranged. A pressure switch 53 and a Manometers 54 belong to the equipment of such a system in a known manner.

On the side of the oil pump 40 facing the pump line 42 there is also a Suction valve 67 arranged, the function of which will be described later. The one already mentioned Flow meter 13 detects the speed of the between the valve unit 43 and the Lift cylinder 3 in the cylinder line 44 flowing pressure oil. It is advantageous within the Valve unit 43 arranged.

A braking unit 81 and / or a can be connected to the power supply part 28 Regenerative unit 82, the function of which will also be described below.

The cabin 2 of such a hydraulic elevator is usually equipped with at least two Nominal speeds operated, namely at a first speed (fast travel) and a second speed (creep speed) and transition phases between them two speeds on the one hand and the second speed (creep speed) and the Standstill, on the other hand, is caused by continuous changes in speed distinguished. The second speed (creep speed) can be, for example, 5 to 10% of the first speed. The elevator control 5 gives due to a Operating action on an external control unit 7 or on the cabin control unit 8 which results in a driving command signal, a control command signal K to the control and Control unit 10 from. so the cabin 2 is set in motion. As will be described later the movement begins with increasing acceleration until reaching the first speed (high speed). When this first speed is reached, the journey begins continued at this constant speed. When approaching the destination begins a delay phase. Finally, within this delay phase, the second one Speed (creep speed) reached. Then the brakes to a standstill. Acceleration and deceleration increase or decrease for comfort reasons. The The problem underlying the invention occurs when driving downhill in the area less Speeds up, namely at speeds approximately equal to or less than the second Speed (creep speed).

According to the invention, when driving downwards in the range of low speeds in start-up and Braking phases the cabin speed by acting on the valve unit 43 regulated while acting at higher speeds by acting on the Power supply part 28 and thus regulated to the motor 39 and the oil pump 40, the valve unit 43 being controlled at the same time. When going up, the Valve unit 43 is not activated and the cabin speed is regulated in all speed ranges by acting on the power supply part 28 and thus on the engine 39 and the oil pump 40.

It is advantageous if the speed of the cabin 2 is the only controlled variable and if the flow meter 13 whose actual value x _{i is} fed to the control and regulating unit 10 is used as the sensor.

This method will now be explained in more detail with reference to FIG. 1. By rotating the motor 39 in one direction, the oil pump 40 also rotates in the one direction. As a result, pressure oil is conveyed into the pump line 42 by the oil pump 40. A pressure arises in the pump line 42, which rises until the check valve 47 contained in the valve unit 43 opens. This opening begins when the pressure in the pump line 42 exceeds the pressure in the cylinder line 44. The pressure oil now flows through the flow meter 13 and the cylinder line 44 into the lifting cylinder 3. As a result, the cabin 2 is moved in the upward direction. The regulation of the speed of the cabin 2 takes place in such a way that the target value x _s predetermined by the target value generator 12 is compared with the actual value x _i supplied by the flow meter 13, which happens within the controller 18. The controller 18 outputs the manipulated variable y to the control block 19. On the basis of the travel command signals also present at the control block 19, the control block 19 forwards the manipulated variable y to the signal converter 27 when driving upwards. In this signal converter 27, an actuating command Y _{M is} generated from the manipulated variable y. The control command Y _M is in its nature matched to the element to be controlled, namely the power supply part 28 with the power controller 29. If the motor 39 is a three-phase motor and the power controller 29 is a frequency converter, the control command Y _M must be adapted to the frequency converter used. For example, the type G9S-2E with brake chopper BU III 220-2 (from Fuji) can be used as the frequency converter. The signal converter 27 is then designed such that an actuating command Y _M that exactly matches this frequency converter type is generated from the manipulated variable y.

When driving upwards, as described, the control unit 10 alone does this Power supply part 28 with the power controller 29, the motor 39 and the oil pump 40 contained effect chain operated. This occurs at all speeds Regulation of the speed by regulating the speed of the motor 39 and thus the Oil pump speed 40.

When driving downhill, the speed is regulated in a different way. In the case of a control command signal for downward travel, the setpoint generator 12 advantageously generates a further setpoint in addition to the setpoint x _s , namely a setpoint x _{M used to} control the motor. This setpoint x _{M is passed} on from the control block 19 to the signal converter 27, which is analogous to the upward travel described above the command Y _M generated. In contrast to the upward movement, this is not a signal within the control chain, but a pure control variable. Accordingly, the motor 39 is initially only controlled, not regulated. Motor 39 and thus oil pump 40 now rotate in the reverse direction. Since the valve unit 43 is not activated and is therefore closed, a negative pressure is created in the pump line 42, which is limited by the automatic opening of the suction valve 67. According to the invention, the valve unit 43, namely the down valve 48, is now also activated. This is done in such a way that the valve drive 24 is activated. By actuating it, the pilot valve 50 is actuated, which in turn acts on the control valve 49. The actuation of the valve drive 24 takes place by means of a control command Y _V , it being irrelevant whether the control command Y _{V is} generated at the beginning of the control from a pure control signal or from a signal of a control chain. According to the invention, however, the control command Y _{V is formed} as part of a regulation at least soon after the start of control. This is done in that the setpoint generator 12 specifies a setpoint x _s for the speed, which the controller 18 compares with the actual value x _i supplied by the flow meter 13 and forms the manipulated variable y as a control signal from the control deviation Δx. The control block 19 forwards this manipulated variable y to the signal converter 22, which converts the manipulated variable y into an actuating command Y _V. The valve drive 24 is actuated with this control command Y _V. With increasing command Y _V , the down valve 48 opens in such a way that the valve drive 24 actuates the pilot valve 50 and this actuates the control valve 49. Now, according to the invention, the speed is regulated by acting on the downward valve 48. At the same time, as mentioned, the motor 39 is only controlled.

As soon as a certain speed is reached, the value of which can be predetermined and which corresponds approximately in size to the second nominal speed (creep speed), the control is switched over according to the invention. This is done in that the setpoint generator 12 generates, in addition to the setpoints x _s (setpoint for the cabin speed) and x _M (control variable for the motor 39), a setpoint x _V which is a control variable for the downward valve 48. According to the invention, the control variable 19, which represents the signal of the control chain, is now switched from the signal converter 22 to the signal converter 27 by the control block 19, while at the same time the signal converter 22 receives the desired value x _V. So that the speed of the cabin 2 is no longer controlled by acting on the down valve 48, but by acting on the speed of the engine 39. So that by controlling the speed of the engine 39 the speed of the cabin 2 is completely manageable, the following the above-described switching process of the controlled variable slowly controls the down valve 48 to the "fully open" position, which is caused by a corresponding increase in the setpoint x _V. The setpoint X _V is generated by the setpoint generator 12 and now represents a pure control variable.

When the destination is approached, the speed of the cabin 2 is reduced by reducing the setpoint x _s . The control is carried out in a continuation of the effect described above by reducing the control command Y _M. At the same time, the setpoint x _{V is} reduced, which means that the down valve 48 is slowly controlled in the closing direction. At the moment when the setpoint x _{s reaches} a predetermined value, which corresponds approximately in size to the second nominal speed (creep speed), the controlled variable is switched over again. The manipulated variable y, that is to say the signal of the control chain, is in turn placed by the control block 19 on the signal converter 22 and the signal converter 27 receives the setpoint x _M. After this switchover, the speed is again regulated by activating the downward valve 48, while the motor 39 is only controlled according to the specifications by the setpoint x _M. Up to a standstill, the speed is now regulated in that the setpoint x _S is reduced by the setpoint generator 12, from which it follows that the downward valve 48 is actuated as part of the regulation in the closing direction until it is fully closed. The cabin 2 thus stands still. In parallel, the control variable for the motor 39, the setpoint x _M , is reduced to zero.

As described, when the motor 39 or the down valve 48 is not as Part of the control chain are operated by the motor 39 or the down valve 48 predefined control variables controlled. This has the advantage that at the moment of Switching process for the controlled variable no instabilities such as control vibrations or Jumps in control behavior occur.

The device according to the invention is in accordance with the aforementioned method characterized in that the control and regulating unit 10 has means by means of which Oil pump 40 and the valve unit 43 can be controlled in such a way that when driving down a speed approximately equal to or less than the second speed (creep speed) the regulation of the speed of the cabin 2 by the control and regulation unit 10 on the basis of the signal from the sensor 13 in such a way that regulating the valve unit 43 is acted upon while driving downwards at a speed approximately equal to or greater the second speed (creep speed) and when driving upwards the regulation of the The speed of the cabin 2 is achieved by regulating the power supply part 28 and thus acts on the motor 39 and the oil pump 40

These means are: firstly the setpoint generator 12, which generates setpoints for the speed of the cabin 2, setpoints x _M for the speed of the engine and solenoid values x _V for the control of the valve unit 43 as a function of control command signals applied to its input, secondly the controller 18, which determines a manipulated variable y from the respective setpoint x _s for the speed of the cabin 2 and an actual value x _i detected by the sensor 13 for the speed of the cabin 2, thirdly, the control block 19, which is a function of the drive command signals K from which Actuating variable y and a set command Y _V for the valve unit 43 and a set command Y _M for the motor 39 from the setpoints x _M and x _V. The control block 19 acts according to the invention in such a way that when driving downwards at a speed approximately equal to or less than the second speed (creep speed), the control command Y _V for the valve unit 43 represents the controlled variable of the control circuit, while when driving downwards at a speed approximately greater than the second speed ( Creep speed) and when driving upward, the command Y _M for motor 39 represents the controlled variable of the control loop.

It is extremely advantageous if, as the only sensor, with its help the speed the cabin 2 is detected, the flow meter 13 is present. The one from this Flow meter 13 to the control and regulating unit 10 correlates with the measured variable the speed of the cabin 2, in all circumstances, for example at Changes in the temperature of the pressure oil associated with a change in viscosity, as well as with changing loads on the cabin 2.

2 shows an exemplary embodiment of the down valve 48 in a partial section. The valve drive 24 can be controlled by the control command Y _V. The command Y _V is a voltage, for example. A magnetic field proportional to this voltage is generated in the valve drive 24 and exerts a force on a magnet armature (not shown in FIG. 2). This magnet armature is connected to a plunger 68, so that the force exerted on the magnet armature also acts on the plunger 68. A spring 69 is also shown, which is supported against a cone 70. The plunger 68 engages in this cone 70, so that the force generated by the valve drive 24 is transmitted to this cone 70. The cone 70 is thereby movable relative to a pilot sleeve 71. The opening cross section that can be released by the stroke of the cone 70 relative to the pilot sleeve 71 determines the effect of the pilot valve 50 (FIG. 1).

Fig. 2 further shows a cylinder chamber 72, which over the not shown Flow meter 13 communicates with the cylinder line 44. Also shown is a with Slits 73 provided control piston 74 which the cylinder chamber 72 from a Control chamber 75 separates. This control chamber 75 is through a bore 76 with a Pilot chamber 94 connected. Beyond the pilot control sleeve 71 there is one Bore 77 leading to tank 41 (Fig. 1).

Reference number 78 is a guide cylinder which serves to guide the control piston 74 designated. There are two openings in the guide cylinder 78 and the slots 73 Passage between the cylinder chamber 72 and the control chamber 75. In addition, the Guide cylinder 78 on its inside and the control piston 74 on its outside like this designed that between them there is a releasable opening cross-section 79, through which Movement of the spool 74 variable size the flow of pressure oil between the Cylinder chamber 72 and a pump chamber 95, which via the pump line 42 with the Oil pump 40 is connected, determined.

The spring 69 already mentioned, which is supported on the one hand against the cone 70, is supported on the other hand against an adjusting screw 92. A compensation pin 93 serves as Safety element in the event of overpressure or breakage of the spring 69. Finally, a piston head 96 shown, which is movable in a bore of the guide cylinder 78 and the precise guidance of the control piston 74 is used.

The left half of FIG. 2 thus essentially shows the control valve 49 (FIG. 1) while to the right of this the pilot valve 50 (FIG. 1) is shown.

2a and 2b show detailed sections of a partial section. Details are shown of the slits 73 in the control piston 74. In conjunction with FIG. 2, FIG. 2a recognizable that the slots 73 extend axially to one end of the control piston 74. The depth of the slots 73 increases to the end of the spool 74 with a slope of for example about 20 degrees linearly. The slots 73 act as inlet shutters Control chamber 75 (Fig. 2). In the closed position of the control piston 74 shown in FIG. 2 the slots 73 expose a minimal opening. With increasing stroke of the control piston 74 the cross-sectional area of these inlet panels increases. This acts as an internal, hydraulic-mechanical negative feedback, with which a higher positioning accuracy, Dynamics and resolution of the movement of the control piston 74 is achieved.

The operation of this down valve 48 will now be described. 2 shows the closed position, which is present when there is no actuating command Y _V on the valve drive 24. In this position, the same pressure prevails in the cylinder chamber 72, in the control chamber 75 and in the pilot chamber 94. As soon as a control command Y _V and thus a voltage is applied to the valve drive 24, the proportional magnet contained in the valve drive 24 generates, as already mentioned, a magnetic field which exerts a force on the tappet 68 and thus on the cone 70. The cone 70 only moves when this force becomes greater than the force exerted by the spring 69. An opening is created between the cone 70 and the pilot sleeve, via which pressure oil can flow from the pilot chamber 94 through the bore 77 into the tank 41. As a result, the pressure in the pilot chamber 94 drops. As a result, the control piston 74 moves and the opening cross section 79 thus differs from zero. As a result, pressure oil can flow from the cylinder chamber 72 into the pump chamber 95, which leads to a downward movement of the cabin 2 (FIG. 1).

With increasing command Y _V , the opening cross section 79 becomes larger. Thus, when the control command Y _{V is} formed and becomes effective within the control chain, the speed of the cabin 2 can be regulated by the action on the down valve 48 contained in the valve unit 43. As already mentioned, this happens when driving downwards at low speeds.

It is advantageous if the down valve 48 is designed so that the piston head 96 of the Control piston 74 has the same diameter as the sealing surface in the area of Opening cross-section 79. None of the pressure in the valve therefore acts on the control piston 74 Pump chamber 95 resulting force. As a result, the control piston 74 is hydraulic balanced, which has a positive effect on the dynamics of the control of the control piston 74.

3 to 6 are explained in more detail below, which represent the movement of the cabin 2 on the basis of selected signals. 3 shows three diagrams. The upper diagram shows in a voltage-time representation the course of the setpoint x _s for the speed of the cabin 2 (FIG. 1). This is only to be understood as an example in the case of an analog control and regulation unit 10 (FIG. 1), in which the setpoint x _{s is represented} by a voltage. In the case of a digital control and regulating unit 10 with a microprocessor, the time course of the setpoint x _{s is represented} by a variable. This also applies in the same way to the following FIGS. 4 to 6. The course of a journey of the cabin 2 (FIG. 1) from one stop to the next stops is shown.

The middle diagram of FIG. 3 shows the course of the actual value x _{i of} the actual driving speed of the cabin 2 measured by the flow meter 13 (FIG. 1). Here too, a voltage-time representation is shown, which represents the voltage signal emitted by the flow meter 13. In the case of a digital control and regulating unit 10 (FIG. 1), this would also be representable as a variable which is output by an analog-digital converter to the control and regulating unit 10 (FIG. 1). If the speed of the cabin 2 (FIG. 1) is properly controlled by the control and regulating unit 10 (FIG. 1), the courses of x _i and x _{s are} almost congruent.

In the lower diagram of FIG. 3, the time course of the command Y _{M is} shown. This control command Y _M is represented by a voltage curve. Below the lower diagram, two control command signals K generated by the elevator control 5 (FIG. 1) are shown, namely a first control signal command K1, which is set during an upward movement and triggered by the approach to the destination is reset by a Schachl pulse generator 4 (FIG. 1), and a second control signal command K2, which is also set when driving upwards, but which is only reset when the cabin 2 (FIG. 1) engages a second shaft pulse generator 4 (Fig. 1), which is placed closer to the intended destination, approaches.

The lower diagram in FIG. 3 shows that by setting the control command signals K1 and K2, the control command Y _{M is set} from zero to a value which corresponds to an offset value U _ofs . The motor 39 (FIG. 1) and consequently the oil pump 40 thus start up. As a result of the inertia, the leakage of the oil pump 40 and the compressibility of the pressure oil, this jump in signal does not cause a jerk in the cabin 2. First of all, a pressure must first be built up in the pump line 42. As soon as this pressure exceeds the pressure in the cylinder line 44, the check valve 47 opens automatically. The offset value U _ofs should therefore advantageously be just large enough that the speed of the motor 39 is just large enough to build up a pressure in the pump line 42. which corresponds approximately to the pressure in the cylinder line 44. The size of the offset value U _ofs can belong to those parameters which are stored in the parameter block 34 and can be changed via the serial interface 35.

Following the start-up of motor 39 with a control command Y _M corresponding to offset value U _ofs , motor 39 is controlled according to a ramp function U _R. The command Y _M now rises continuously. A threshold value U _{0 is} shown in the middle diagram of FIG. 3. This threshold value U _{0, which} is preferably also adjustable as a parameter, is, for example, approximately 0.5 to 2% of the maximum value of the desired value x _S or of the actual value x _i . At this moment, the control is ended according to the ramp function U _R and thus the regulation of the speed of the cabin 2 is started. This method of initially controlling the speed with a transition to regulating the speed is particularly advantageous because the transition from the control to the regulation takes place at the moment when a certain speed has been reached in the context of the control. This means that no jump functions or control vibrations occur during the transition from control to regulation.

The further course of the control command Y _{M over time} is thus solely the result of the control of the motor 39 by the controller 18 on the basis of the setpoint x _s, the speed of the cabin and the actual value x _i . The curve for the setpoint x _s (upper diagram) then rises to a maximum that corresponds to the first speed (fast travel) already mentioned. The course of the actual value x _i and the course of the control command Y _M now result as a result of the control.

As soon as the control _{command signal} K1 is reset, a delay _phase P _delays (upper diagram in FIG. 3). The setpoint x _s is now reduced by the setpoint generator 12 (FIG. 1) according to the representation of the curve. The course of the actual value x _i and the course of the control command Y _M again result from the regulation. The end of the deceleration _phase P _verz is characterized by the stepless transition to a speed that corresponds to the second speed mentioned (creep speed). If the control signal command K2 drops due to the approach of the cabin 2 (FIG. 1) to the second shaft pulse generator 4 (FIG. 1), the setpoint x _s is generated by the setpoint generator 12 in accordance with a softstop setpoint curve K _ss (upper diagram in FIG. 3), which is characterized by a smooth transition from the second speed (creep speed) to standstill. The course of the actual value x _i and the course of the control command Y _{M also} result here as a result of the regulation of the motor 39 by the controller 18. The reduction in the speed of the motor 39 reduces the amount of pressure oil delivered by the oil pump 40. As a result of the leakage of the oil pump 40, if the speed of the motor 39 is still finite, the amount of pressure oil delivered drops to zero. As a result, the pressure in the pump line 42 generated by the oil pump 40 is also reduced. As soon as this pressure falls below the pressure in the cylinder line 44, the check valve 47 closes automatically, which leads to the standstill of the cabin 2.

While a first variant of the control and regulation during upward travel is shown in FIG. 3 described above, a second variant will now be described with reference to FIG. 4. FIG. 4 largely corresponds to FIG. 3 and only the differences from FIG. 3 are described below. In the method according to FIG. 4, the offset U _ofs and the ramp function U _R for the control command Y _{M are} dispensed with. Instead, the function for the setpoint x _{s of} the speed of the cabin 2 is started with an offset x _ofs . This means that a regulation is started from the beginning. Despite the setpoint jump at the beginning, namely from x _s equal to zero to x _s equal to x _ofs , as the middle diagram for the actual value x _i shows, there is no jump in the speed actually reached, although due to the control the control command Y _M jumps from zero to a finite value Y _Mo at the beginning. The reasons have already been mentioned in the description of FIG. 3: because of the inertia, the leakage of the oil pump 40 and the compressibility of the pressure oil, the approach is nevertheless smooth.

Two alternative methods for downward travel are now described below with reference to FIGS. 5 and 6. 5 shows a first method for the downward travel on the basis of selected signals. 5 shows four diagrams. The upper diagram shows in a voltage-time representation the course of the setpoint x _s for the speed of the cabin 2 (FIG. 1) in the same way as in FIGS. 3 and 4. It is also analogous to FIGS. 3 and 4 the curve of the actual value x _{i of} the speed of the cabin 2, represented by the measured value of the flow meter 13 (FIG. 1), is shown in the second diagram from above. The third diagram shows the course of the control signal Y _{V over} time, which is output by the control and regulating unit 10 to the valve drive 24 for controlling the downward valve 48. The lower diagram again shows, analogously to FIGS. 3 and 4, the time course of the control command Y _M. At the bottom, two control command signals K generated by the elevator control 5 (FIG. 1) are shown, namely a third control signal command K3, which is set during a downward movement and is reset by the approach to the destination, triggered by a shaft pulse generator 4 (FIG. 1) , and a second control signal command K4, which is also set when driving downwards. but this is only reset when the cabin 2 (FIG. 1) approaches a second shaft pulse generator 4 (FIG. 1), which is placed closer to the intended destination.

By means of the control command signals K3 and K4, the setpoint generator 12 (FIG. 1) of the control and regulating unit 10 at the time t ₀ (third diagram from above, this time axis applies to all four diagrams) first of all an offset value U _ofsM (lower diagram) for generates the command Y _M and supplied from the control block 19 to the power supply section 28. Motor 39 and pump 40 thus rotate at a corresponding predetermined speed. Only the absolute value is shown here, but it can already be seen from the aforementioned that the direction of rotation of motor 39 and pump 40 is reversed with respect to the upward travel. This creates a negative pressure in the pump line 42. In order to limit this vacuum so that cavitation of the pump 40 is avoided, the suction valve 67 now opens.

At the same time, at time t _0, the setpoint generator 12 (FIG. 1) of the control and regulating unit 10 first generates an offset value U _ofsV (third diagram from above) for the control command Y _V and supplies it from the control block 19 to the valve drive 24 for actuating the downward valve 48 , The size of the offset value U _ofsV is such that the force exerted by the magnet armature on the tappet 68 (FIG. 2) is even smaller than the pretension of the spring 69, so that the cone 70 does not yet lift off from the pilot sleeve 71. The cone 70 does not yet make a stroke, so that the pilot valve 50 (FIG. 1) remains closed.

At time t ₀ , a first setpoint ramp U _R1 for the control command Y _{V is also} started. The force generated by the valve drive 24 and exerted on the tappet 68 (FIG. 2) thus increases. As soon as this force exceeds the pretension of the spring 69, the cone 70 lifts off the pilot sleeve 71. Consequently, the pilot valve 50 and subsequently also the control valve 49 open. Thus, pressure oil can escape from the cylinder line 44 in the direction of the tank 41 and the movement of the cabin 2 (FIG. 1) begins. This is expressed directly by the fact that the actual value x _i becomes different from zero, as the second diagram shows.

As soon as the speed of the cabin 2 has reached a first threshold value x ₁ (second diagram), the first setpoint ramp U _R1 for the actuating command Y _{V is} terminated. This corresponds to time t ₁ . At this moment, a second, somewhat flatter setpoint ramp U _R2 for the command Y _{V is} started. As a result, the increase in speed of the movement of the cabin 2 is limited, so that a jerk does not occur. As soon as the speed of the cabin 2 has reached a second threshold value x ₂ (second diagram), the second setpoint ramp U _R2 for the actuating command Y _{V is} terminated. This corresponds to time t ₂ .

At time t ₂ , the function for the setpoint x _{s of} the speed of the cabin ₂ is now started with an offset value x _ofs . This means that at that moment the pure control is ended and regulation is started. Despite the setpoint jump from x _s equal to zero to x _s equal to x _ofs , as the second diagram for the actual value x _i shows, there is no jump in the speed actually reached. This can be achieved in that the offset value x _ofs is chosen to be the same size as the second threshold value x ₂ . But even if this were not the case, the transition from control to regulation would still be smooth due to the inertia and the compressibility of the pressure oil.

Now, from time t _2, the speed of cabin 2 (FIG. 1) is regulated by comparing actual value x _i and setpoint x _s from controller 18 and generating an actuating command Y _V via actuating signal y and control block 19 and sending it to Valve drive 24 is sent, which is a real control variable. The speed of the cabin 2 is now regulated by influencing the downward valve 48.

In accordance with the increasing setpoint x _s , the control command Y _V and the actual value x _{i also increase} . As soon as the setpoint x _{s has reached} a threshold value x ₃ , which is the case at time t ₃ , the control is switched over. The control block 19 no longer generates the control command Y _V for the downward valve 48 from the control signal y, but rather the control command Y _M for the power supply part 28, and thus for the motor 39.

At the same time, the control block 19 continues to generate the control command Y _V , but now no longer on the basis of the manipulated variable y, but on the basis of the specification of set values x _V (FIG. 1) which the set value generator 12 generates. The setpoint x _V then rises relatively quickly, which is expressed in the rising control command Y _V (FIG. 5, third diagram from above). The downward valve 48 is thus controlled in the "fully open" direction and thus increasingly and ultimately completely loses an effect on the speed of the cabin 2. The regulation of the speed of the cabin 2 now takes place exclusively in such a way that the controller 18 setpoint x _s and Iscert compares x _i , forms the manipulated variable y from it, which is then converted by the control block 19 into an actuating command Y _M. This command Y _{M is} part of the control chain.

As previously described during the upward movement, the setpoint x _s now rises to a maximum and the control and regulating unit 10 accordingly ensures that the control command Y _M increases accordingly. As a result, the actual value x _{i also increases} .

Analogous to the upward movement, a delay phase is initiated when the control signal command K3 drops. The setpoint x _{S is} reduced accordingly, from which it follows within the scope of the control that the control command Y _M and subsequently the actual value x _{i also} fall. At the same time, the setpoint x _{V is} reduced in accordance with the specifications by the setpoint generator 12, which manifests itself in the reduction in the actuating command Y _V (FIG. 5, third diagram).

With the actuation of the down valve 48 in the closing direction, caused by the reduction of the control command Y _V , the down valve 48 increasingly gains influence on the flow of the pressure oil from the cylinder 3 (FIG. 1) back into the tank 41. This increasing influence is however automatically caused by a corresponding one Adjustment of the control command Y _M compensated. At almost any point in time within the delay _phase P _verz , the control can again be switched from the control command Y _M to the control command Y _V. At the moment the second speed is reached (creep speed), whereby the drop in the control signal command K4 is determinative, analogously to the upward movement, the state is reached again that the control command Y _V results from the regulation by the controller 18, while the control command Y _M is determined by the reference-value generator 12 due to the setting of the target value _V X. Until standstill, the speed of the cabin 2 is then regulated in accordance with the specification of the setpoint x _s (upper diagram) exclusively by the further closing of the down valve 48 resulting from the control command Y _V generated via the control variable y.

At the moment the down valve 48 is completely closed, the cabin 2 is at a standstill again.

The fact that the control signal Y _V still has a finite value when the cabin 2 is at a standstill has to do with the fact that the pilot valve 50 already closes due to the effect of the bias of the spring 69 when a control signal Y _V of finite size at the valve drive 24 is still present is applied.

6 shows a second variant of the descent. This variant differs differs from the variant shown in FIG. 5 in the same way as this when driving upwards the case according to FIG. 4 in comparison to the upward travel according to FIG. 3: the ramp functions this variant does not apply and regulation is started from the beginning.

In both variants of the downward movement, opening the downward valve 48 causes the pressure exerted by the cabin 2 in the cylinder line 44 and pump line 42 to act on the oil pump 40 in such a way that the oil pump 40 is driven by the pressure oil. The motor 39 coupled to the oil pump 40 therefore does not require any energy, but now acts as a generator. The speed of the motor 39 is regulated with the aid of the control signal Y _M. The electrical energy generated by the motor 39 is either converted into heat in the brake unit 81 or converted into reusable electrical energy by means of the regenerative unit 82 and fed back into the power supply network L1, L2, L3. It is therefore necessary for one of these units 81, 82 to be present.

The third signal converter 30 mentioned at the beginning receives information from the control block 19 the operating status. The signal converter 30 gives the power supply part 28 Information about the direction of travel, i.e. upward or downward travel, so that the Power supply part 28 including power controller 29 accordingly between the drive and Brake control can switch.

For the sake of completeness, it should also be mentioned that the mentioned status signals S _St serve to inform the setpoint generator 12 and subsequently also the control block 19 about the actual operating state of the power supply part 28. This makes it possible, for example, to detect a malfunction in the power supply part 28 and to let the control block 19 take the safety-relevant measures.

The control and regulating unit 10 is advantageously designed as a microprocessor control. The Details shown in Fig. 1 with setpoint generator 12 and control block 19 and their Functionality is then realized by program code. The inputs and outputs of the control and Control unit 10 are then used by analog-digital converters or digital-analog converters educated.

In the event that an oil pump 40 with a very small leak rate in a hydraulic elevator is used, it may be advantageous to control a Valve unit 43 can also be used analogously when driving upwards at low speed.

Claims (11)

1. Method of controlling a hydraulic lift comprising a car (2) which can move up and down along a lift shaft (1), a reciprocating piston connected to the car (2), a lifting cylinder (3) for driving the reciprocating piston, an oil pump (40) for driving the car (2) by means of hydraulic oil, a motor (39) for driving the oil pump (40) supplied with power by a controllable power-supply unit (28), a valve unit (43) installed between a pump line (42) and a cylinder line (44), a sensor (13) for the speed of the car (2) and a control unit (10) by means of which the movement of the car (2) can be influenced, the car (2) being operated at at least two nominal speeds, namely at a first speed (high speed) and a second speed (creep speed) and transition phases, on the one hand, between these two speeds and, on the other hand, between the second speed (creep speed) and stoppage, said transition phases being characterised by a continuous change in speed, characterised in that, during downward travel at a speed substantially equal to or lower than the second speed (creep speed), the speed of the car (2) is controlled by the control unit (10) on the basis of the signal from the sensor (13) in such a manner that the controlling action is exerted on the valve unit (43), whereas during downward travel at a speed substantially equal to or higher than the second speed (creep speed) and during upward travel, the speed of the car (2) is controlled in such a manner that the controlling action is exerted on the power-supply unit (28) and therefore on the motor (39) and the oil pump (40).
2. Method according to claim 1, characterised in that, during downward travel at a speed substantially equal to or lower than the second speed (creep speed), the speed of rotation of the oil pump (40) is determined by predetermined values.
3. Method according to claim 1 or claim 2, characterised in that the speed of the car (2) is the only controlled variable and that a flowmeter (13) the actual value x_i of which is supplied to the control unit (10) is used as the sensor.
4. Method according to one of claims 1 to 3, characterised in that, when the movement of the car (2) is started, the onset of the closed-loop control of the speed of the car (2) is preceded by a phase with open-loop control of the speed of the car (2) with predetermined values for the speed, this phase ending when the speed reaches a predetermined value (U₁, x₁).
5. Device for controlling a hydraulic lift, comprising a car (2) which can move up and down along a lift shaft (1), a reciprocating piston connected to the car (2), a lifting cylinder (3) for driving the reciprocating piston, an oil pump (40) for driving the car (2) by means of hydraulic oil, a motor (39) for driving the oil pump (40) supplied with power by a controllable power-supply unit (28), a valve unit (43) installed between a pump line (42) and a cylinder line (44), a sensor (13) for the speed of the car (2) and a control unit (10) by means of which the movement of the car (2) can be influenced, the car (2) being operated at at least two nominal speeds, namely at a first speed (high speed) and a second speed (creep speed) and transition phases, on the one hand, between these two speeds and, on the other hand, between the second speed (creep speed) and stoppage, said transition phases being characterised by a continuous change in speed, characterised in that the control unit (10) has means (12, 18, 19, 22, 27) with the aid of which the oil pump (40) and the valve unit (43) can be actuated in such a manner that, during downward travel at a speed substantially equal to or lower than the second speed (creep speed), the speed of the car (2) is controlled by the control unit (10) on the basis of the signal from the sensor (13) in such a manner that the controlling action is exerted on the valve unit (43), whereas during downward travel at a speed substantially equal to or higher than the second speed (creep speed) and during upward travel, the speed of the car (2) is controlled in such a manner that the controlling action is exerted on the power-supply unit (28) and therefore on the motor (39) and the oil pump (40).
6. Device according to claim 5, characterised in that

   the control unit (10) has a setpoint generator (12) which generates setpoints for the speed of the car (2), setpoints x_M for the speed of rotation of the motor and setpoints x_v for the actuation of the valve unit (43) as a function of control command signals K present at an input,

   a controller (18) is provided and determines a correcting variable y from the respective setpoint x_s for the speed of the car (2) and an actual value x_i for the speed of the car (2) detected by the sensor (13),

   a control block (19) is provided and generates a control command Yv for the valve unit (43) and a control command Y_M for the motor (39) as a function of the travel command signals K, the correcting variable y and the setpoints x_M and x_v, and,

   during downward travel at a speed substantially equal to or lower than the second speed (creep speed), the control command Y_v for the valve unit (43) represents the controlled variable of the control circuit, whereas, during downward travel at a speed substantially higher than the second speed (creep speed) and during upward travel, the control command Y_M for the motor (39) represents the controlled variable of the control circuit.
7. Device according to claim 6, characterised in that the sensor for the speed of the car (2) is a flowmeter (13), the actual value x_i of which has a determining influence on the control of the speed of the car (2) in all speed ranges.
8. Device according to one of claims 5 to 7, characterised in that the valve unit (43) consists of a non-return valve (47) and a down valve (48) arranged parallel thereto, the non-return valve (47) being opened when the pressure in the pump line (42) is higher than the pressure in the cylinder line (44), and in that the down valve (48) can be actuated by the control unit (10).
9. Device according to claim 8, characterised in that the down valve (48) consists of a pilot valve (50) and a control valve (49) actuated by this pilot valve (50).
10. Device according to claim 9, characterised in that the pilot valve can be actuated electrically.
11. Device according to claim 10, characterised in that the electrically actuated drive of the pilot valve (50) has a valve drive (24) which changes the opening cross section of the pilot valve (50).

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