WO2001090621A1

WO2001090621A1 - Damping device for a safety drive of an actuating drive and a corresponding actuating drive

Info

Publication number: WO2001090621A1
Application number: PCT/AT2001/000155
Authority: WO
Inventors: Stephan Vasiljevic
Original assignee: Schiebel Antriebstechnik Gesellschaft M.B.H.
Priority date: 2000-05-19
Filing date: 2001-05-18
Publication date: 2001-11-29
Also published as: ATA8742000A; AT411704B; AU2001258027A1

Abstract

The invention relates to a damping device (35) for a safety drive (13) of an actuating drive (1) for an armature or similar actuator, whereby the safety drive (13) can be activated in the event of a malfunction or during a power failure for positioning the actuator in a predetermined safety position with damping effected by the damping device (35). Said damping device (35) has an energy converter, whereby the energy converter comprises an electric generator (5), which is connected to the safety drive (13) and which converts kinetic energy into electrical energy, and comprises an electric load resistor (28) that is connected to the generator (5).

Description

Damping device for a safety drive of an actuator and actuator

The invention relates to a damping device for a safety drive of an actuator for a valve or the like. Actuator, wherein the safety drive can be activated in the event of a malfunction, in the event of a power failure, to position the actuator in a predetermined safety position with damping by the damping device, which damping device has an energy converter.

Actuators, in particular electrical actuators, but possibly also hydraulic or pneumatic actuators, are used, for example, to actuate fittings, such as slides, flaps or the like. Control elements in media lines, for example in the area of power plants, refineries, in the paper and cellulose industry, wastewater treatment, etc. , These actuators can be designed as linear actuators, swivel drives or rotary drives and contain an electric motor, the rotary movement of which is converted into a desired actuating movement (eg rectilinear drive movement, swivel movement or rotary movement) via gear devices. In addition, a safety drive with a mechanical energy store (e.g. in the form of springs, such as in particular disc spring assemblies, but possibly also in the form of drop weights, for example) is installed in such actuators, so that in the event of a malfunction, if the driving force of the motor or its holding force (or but the holding force of an assigned electric brake unit) fails to move the actuator into a predetermined safety position (eg "open" or "closed"). This would happen more or less abruptly without damping. which, among other things, leads to a strong setback when the moving part hits a stop, for example a valve body on a valve seat. Such an "exploding" of the actuating speed or exorbitantly high. In order to prevent speeds in the event of safety (so-called "fail-safe" case) at low moments, damping devices are provided which are currently regularly implemented by old dampers with speed-proportional damping characteristics. However, such old dampers are not only relatively complex to manufacture and maintain, they also enable the achievement to a very limited extent only damping characteristics as would be desired in many cases.

It is therefore an object of the invention to provide a damping device as stated at the outset, which is structurally simple and space-saving and is easy to maintain, and which enables a wide variety of damping characteristics to be defined with regard to an individual adaptation of the damping for the respective actuator.

The damping device according to the invention of the type mentioned is characterized in that the energy converter has an electrical generator connected to the safety drive for converting kinetic energy into electrical energy and an electrical load connected to the generator.

Unlike the known oil dampers, where kinetic energy is "destroyed" with the help of displacers and throttles, i.e. is converted into heat energy, in the present concept an electronic damper is realized, in which the generator, which is driven by the safety drive in the event of a fault, generates an electrical current which is fed to an electrical load, where, for example, a heat loss output is produced for damping or the supplied electrical energy is used in some other way, possibly stored, with the generator being braked. A special damping characteristic can be achieved in a simple manner by appropriate design of the electrical load, and the overall design of this electronic damper is comparatively simple, clean and space-saving. A generator of its own can be used here, but for additional simplification, a motor / generator with permanent excitation or with self-excitation is used, which at the same time forms the motor for the electric actuator. This results in a further saving of space, since the motor / generator itself is already required for the actuator, and only additional electronic components are required as additional components for the damping device, which can be integrated into the respective actuator with the least effort.

A major advantage of the present electronic damper is that larger setting ranges can be achieved compared to oil dampers, in particular the duration of the actuating time in the event of a fault (the so-called fail-safe time) can be long; long adjustment times, on the other hand, are critical with oil dampers or not possible. On the other hand, if the lines are closed too quickly, water hammer effects can occur.

For reasons of circuit technology and for reasons of simple damping adjustment, it is also advantageous if the electrical load is fed by the generator via a rectifier circuit. Depending on the design of the generator, the rectifier circuit can be designed with a simple rectifier, with a two-way rectifier or, in the case of a three-phase system, with six rectifiers.

To adjust the damping depending on the application, a suitable electrical load could be attached to the damping device. With regard to a simple structure of the damping device which makes subsequent installation of the electrical load unnecessary, however, it is advantageous if the electrical load can be set. In the simplest case, a potentiometer would be possible, for example, to adjust the electrical load with regard to heat loss. However, in order to have further options for the specific setting of the respective damping, it is particularly advantageous if a damping control circuit with adjusting elements is assigned to the electrical load. To achieve simple protection for the generator, it is expedient if the control circuit has a current limiter setting element. (The torque of the generator is a function of the current.) To stabilize the speed (which is proportional to the voltage), a voltage-dependent setting element, e.g. a Zener diode can be provided. Furthermore, in order to allow the damping to take effect only from a certain speed, it can advantageously be provided that the control circuit has a damping start setting element, for example an initial voltage setting potentiometer in a comparison circuit. This takes advantage of the fact that the voltage output by the generator is a linear function of the speed.

In order to be able to easily set the speed at which the damping of the present damping device takes effect, depending on the application, it is expedient if the control circuit has an adjusting element for setting the slope of a damping characteristic. With a flat incline there is gentle damping, with a steep characteristic the damping is "hard". The damping device with the above setting elements can easily be constructed with conventional circuit components, in particular with potentiometers and operational amplifiers. For a particularly effective setting and control of the damping, wherein information about the generator or motor / generator is also automatically processed, it is advantageous if the control circuit is formed by a microcomputer with at least one parameterization input. With such a microcomputer, depending on the actuator and fitting, appropriate parameterization can be carried out via its input, the setting values or parameters thus entered being stored in the memory of the microcomputer. This parameterization can include the beginning of the damping, the slope of the damping characteristic and the value at which the speed is stabilized, depending on the generator used. In addition, as mentioned, generator data or motor / generator data can be used automatically, it being particularly advantageous if the microcomputer is connected as a subsystem to a master electronic circuit that supplies motor-specific data. Such a master electronic circuit is regularly present and assigned to the electric motor of the actuator for actuating it in normal operation.

With the above-described damping devices, a certain damping can thus always be achieved in practice by drawing a certain current from the generator and utilizing it in the electrical load or destroying it by conversion into thermal energy.

A particularly simple damping circuit, albeit with only limited setting options, can be achieved if the electrical load is formed by at least one Zener diode. Such a Zener diode limits the voltage upwards, and it can be determined, for example, that no damping takes place up to a voltage of, say, 120 volts, and from this voltage, the Zener voltage of the Zener diode, there is a very strong damping effect and thus speed stabilization ,

The invention also relates to an actuator with a Dämpfungseinric device as indicated above, the transmission elements present in the actuator being non-self-locking. It is also the case that the generator of the damping device is formed by the motor / generator of the electric actuator itself, i.e. by a motor with self or permanent excitation, of particular advantage if the motor / generator via an electrically operated changeover switch in normal operation with a motor control circuit and in the event of a fault, in the event of a power failure, with the electrical Load is connected. The changeover switch can be a relay or contactor, with the connection from the motor / generator to the electrical load being established in the rest position. In the event of a current flow, the changeover switch is brought into its working position in which the motor / generator is connected to the motor control circuit, for example with a frequency converter.

The invention is further explained below on the basis of preferred exemplary embodiments illustrated in the drawing, to which, however, it should not be limited. Show it:

Fig.l schematically an electric spindle drive with a linearly moving spindle for actuating a valve, not shown;

Fig.la part of this spindle drive in axial section and on a larger scale;

2 shows a schematic representation of a spindle drive with a 90 ° positioning movement;

3 shows a block diagram of an electronic damping device for the actuator of Fig.l or Fig.2;

4 shows a detailed circuit diagram of the rectifier circuit of this damping device;

5 shows a more detailed circuit diagram of the voltage supply circuit for self-supplying the damping device;

6 shows a more detailed circuit diagram of a control circuit of such a damping device constructed with discrete components;

7 shows a typical damping characteristic; and

8 shows a circuit diagram of a simple electronic damping device for an actuator according to FIG. 1 or 2.

FIGS. 1 and 1A show an electric actuator 1 in the form of a linear actuator, which is fastened to a housing of a valve (not shown) via a valve connection flange 2. This connection flange 2 is firmly connected to a "linear" housing 3, with which a laterally projecting housing housing 4 is firmly connected, which receives a drive motor 5 together with the associated motor brake and damping device. This motor 5 drives a non-self-running motor worm 6 and a superposition gear (non-self-locking planetary gear) 7 also a non-self-locking planetary roller spindle 8, which passes through a spindle nut 9 axially. An axial bearing 10 is also provided for the spindle 8.

The spindle nut 9 is, as can be seen with a double arrow in Fig.l, linearly movable, and it is secured against rotation with respect to the housing 3. On the underside of the spindle nut 9, a push tube 11 is connected, which is provided with a spindle connection 12 for connection to the spindle of the valve (not shown). This push tube 11 is surrounded on the outside by a mechanical safety drive 13, which is designed, for example, with a plate spring package 14 as a mechanical energy store, this plate spring package 14 in the exemplary embodiment shown being located on the one hand on the housing 3, namely, according to FIG. 1A on the fitting connecting flange 2, and on the other hand supported on a part connected to the spindle nut 9 (according to FIG. 1A with a pressure plate 15 on the push tube 11); in the embodiment shown in FIG. 1A, the safety position is the open position of the fitting, the disk spring assembly pushing the spindle nut 9 upwards; if the "fail-safe" position is the closed position, the pressure plate 15 would have to be attached in the lower end region of the push tube 11, and the plate spring package 14 would be supported with the other, upper end on the upper housing flange 2 '. In both cases, the force can be transmitted from the disk spring assembly 14 via the pressure plate 15 and the push tube 11 to the spindle nut 9 - either upwards or downwards. The plate spring package 14 is accommodated in a spring cup 16 according to FIG. 1A. A mechanical end stop 17 is fastened to the push tube 11 below the connecting flange 2, the push tube 11 coming into abutment on the underside with this end stop 17 when the spindle nut 9 is in its uppermost position (see the illustration in FIG. 1A accordingly an open position).

In the present actuator 1 according to Fig.l and 1A, the safety position for the valve is the open position, in which the spindle nut 9 with the push tube 11 in Fig.lA. apparent upper position in which it is pressed by the plate spring assembly 14 when the motor 5 - in the event of a fault, due to a power failure - no counterforce is applied in the direction of closing the valve and no holding force is effective. It is essential that all of the gear elements 6, 7, 8, 9 mentioned are non-self-locking, so that ^' the force of the plate spring assembly 14 in the upward direction can lead to the upward movement of the push tube 11. During this safety upward movement, the motor 5 is also driven to rotate via the motor worm 6, this motor 5, which is, for example, a permanently excited motor (or a motor with self-excitation) being operated as a generator, as will be explained in more detail below with reference to FIG .3 will be executed.

For the sake of completeness, FIG. 1 also shows a handwheel 18 to be provided for safety reasons for manual actuation of the valve (not shown); this handwheel 18 is connected via a type of freewheel device (load torque lock) 19 to the sun gear shaft of the planetary gear 7, the handwheel 18 not being driven in normal operation when the motor 5 is running ^' . However, if the handwheel 18 is turned by hand, the load torque lock 19 couples the handwheel 18 to the sun gear shaft 20.

Finally, a user interface 21 is illustrated schematically in FIG. 1 in the area of the electronic or electrical part, with the motor 5 including the brake and damping device, via the electronic settings for the motor 5 _. and can be made for the damping device.

2 shows a somewhat modified electric actuator 1 with a 90 ° fail-safe device; parts corresponding to those that are also present in the embodiment according to FIGS. 1 and 1A are provided with the same reference numerals, and a new explanation of these parts, insofar as they are the same and have the same effect, may be omitted below. Therefore, only the differences in the construction of this actuator 1 according to FIG. 2 compared to those according to FIGS. 1 and 1A will be discussed in the following.

In the actuator 1 according to FIG. 2, the spindle nut 9 drives via an unwinding gear 22, which implements a conversion to a 90 ° movement, and via a coupling, a valve shaft 23, which is mounted in a housing part with a valve connection flange 2 'on a main housing, which is designed here as a 90 ° housing 3'. Here, too, all gear elements 6, 7, 8, 9, 22 are not self-locking, so that in the event of a malfunction the force exerted by the plate spring assembly 14 on the spindle nut 9 can on the one hand drive the valve shaft 23 in a rotating manner and on the other hand can also drive the permanently excited motor 5, to make it act as a generator.

In order to achieve damping of the safety drive movement, an electronic damping device is provided in connection with the motor / generator 5, the principle of this damping device being illustrated in FIG. 3.

As can be seen from FIG. 3, the plate spring package 14 or generally the safety drive 13 drives the motor / generator 5 via the mechanical implementation designated in general in FIG. 3 by 24 (cf. elements 6 to 9 in FIGS. 1 and 2) on when a fault occurs in which the electrical actuator 1 (Fig.l and 2) driving electrical energy fails. In the event of such a power failure, a switch 25 assigned to the motor / generator 5 is moved from its working position shown in broken lines in FIG. 3, in which the motor / generator 5 is connected to a motor controller with frequency converter, shown at 26 in FIG Rested in which a rectifier 27 connects to a controllable electrical load 28. In this power failure mode, the safety drive 13 drives the permanently excited motor / generator 5 via the conversion 24, so that it acts as a generator and outputs a voltage to the load 28 via the rectifier 27. An electromechanical brake 29, which is also shown in FIG. 3 and which can be used in normal operation to determine the position of the motor / generator 5 and thus to fix a valve setting, is also deenergized in this fault and thus has no function.

The controllable load 28 is assigned a control circuit 30, which is supplied with a DC voltage via its own voltage supply circuit 31, which is connected to the output of the rectifier 27. Furthermore, the control circuit 30 has an input 32 for parameterization and an input 33 for an external damping characteristic specification. The control circuit 30 can be implemented, for example, by a microcomputer (μC), which has its own memory to store the entered damping parameters and thus according to the set values, depending on the valve to which the actuator is assigned, and also depending on the actuator or its spring actuator 14 and on the motor / generator parameters Control energy destruction in the load 28. The control circuit 30 can also be connected as a subsystem to a master electronic circuit 34, which is connected to the motor / generator 5 and has the corresponding motor data available in order to pass it on to the control circuit 30. As a result, the control circuit 30 implemented, for example, by means of a μC, knows the voltage and the speed of the motor / generator 5, and, depending on this, it can control the load 28 in such a way that the desired damping characteristic of the electronic damping device - which is designated 35 in FIG - is obtained. In this way, a certain damping can be set by the corresponding control of the load 28 by the control circuit 30 by drawing a certain current from the motor / generator 5. The damping characteristic can, for example, be set such that up to a certain initial voltage, for example V ^ = 120 V (see also FIGS. 6 and 7), there is no damping or braking of the motor / generator 5. The lower this initial voltage V _Aaf and the steeper the characteristic curve (see Fig. 7), the lower the generator speed; As a result, long positioning times for transferring the associated valve to the safety position can be achieved, a function that is practically impossible to achieve with conventional oil dampers. In order to protect the motor / generator 5, the current is not increased further.

4 shows a special circuit for the rectifier 27 in the case of a three-phase motor / generator 5 with permanent excitation, as shown in FIG. 3, a total of six rectifier diodes ensuring an all-way rectification. The voltage output by the rectifier 27 is denoted by Vgl. This voltage Vgl is applied to the load 28 and is also supplied to the voltage supply part 31, an embodiment of which is shown in FIG. 5 as an example. A Zener diode 36 is connected in series with a series resistor 37, and a capacitor 38 is connected in parallel to the Zener diode 36, from whose positive electrode the stabilized supply voltage V + for the control circuit 30 can be taken off. 6 then shows a circuit diagram of a control circuit 30 including the load 28, the load 28 being a resistor 39 in series with a field effect transistor (FET) ^'40 , via which the heat loss is adjusted by appropriate current control. Specifically, a current source circuit 41 is assigned to the FET 40, which has an operational amplifier 42, at whose one input "-" a signal corresponding to the actual current through the load 28 and taken from a measuring shunt 43 is fed, whereas the other input "+" has a Signal corresponding to the desired current is supplied via a voltage divider 44. This voltage divider is connected to the output of a differential amplifier 45, which contains a potentiometer 46, with the aid of which the slope of the damping characteristic curve 47 (see FIG. 7) can be set, and which contains two amplifiers 47, 48, the "-" - Inputs are connected to one another via the potentiometer 46.

The "+" inputs of the two amplifiers 47, 48 of the differential amplifier are connected to a potentiometer circuit 49 for setting the initial voltage V _Αnf - from which damping is effected - or to a voltage divider with resistors 50, 51 as a measure of the Actual voltage, ie for the speed of the motor / generator 5, connected.

Furthermore, a current limiting circuit 52 with a setting potentiometer 53 is shown in FIG. 6, which is connected in parallel to the current source circuit 41 to the output of the differential amplifier 45 and, by adjusting the potentiometer 53 accordingly, sets the current to an upper limit value I _G (see FIG. Fig. 7) limited.

In FIG. 7, the damping characteristic curve 47 is illustrated schematically with the beginning of the damping at the initial voltage V _tof and with the current limitation at I _G as well as with a predetermined slope (tan) set with the aid of the setting element 46. From the initial voltage V ^, ie from a certain speed of the motor / generator 5, current is drawn and, for example, destroyed in the load 28, ie converted into heat dissipation. From the initial voltage V ^ _f , the drawn current increases proportionally to the voltage V up to the current limit I _G> , the width of this range, in which the damping increases linearly with the speed of the motor / generator 5, by adjusting the slope using the Potentiometer setting element 46 can be adjusted. Then the drawn current is limited, so that the torque of the motor / generator 5 cannot continue to increase.

Finally, FIG. 8 shows a very simple embodiment of an electronic damping device 35, in which case a Zener diode 54 is simply connected to the motor / generator 5 via the changeover switch 25 and the rectifier 27 as an electrical load 28. This zener diode 54 has a predetermined zener voltage of, for example, U _z = 120 volts, above which the current rises steeply.

Of course, in the case of a three-phase motor / generator 5, it is also possible to use a six-way rectification as shown in FIG. 4 in combination with a zener diode 54, the latter in FIG. 4 being to be switched between the rectifier voltage Vgl and ground.

With the electronic damping device described, it is advantageously possible to achieve a fail-safe actuation movement with the aid of the mechanical energy store with a damping characteristic that can be specifically adapted to the respective application using simple means, with long setting times possibly also being achievable are. A further advantage is that the energy can be switched off briefly, for example for a few seconds, for testing purposes, and via a sensor system in the electric actuator, in particular with a displacement sensor that is. Spindle nut 9 (Fig.l and 2) is assigned, it can be determined whether a "fail-safe" movement takes place. On. In this way, a functional test of the fail-safe drive is made possible at regular intervals and with the least effort.

Claims

claims

1. Damping device (35) for a safety drive (.13) of an actuator (1) for a valve or the like. Actuator, wherein the safety drive (13) in the event of a malfunction, in the event of a power failure, to position the actuator in a predetermined safety position with damping Can be activated by the damping device (35), which damping device (35) has an energy converter, characterized in that the energy converter has an electrical generator (5) connected to the safety drive (13) for converting kinetic energy into electrical energy and one with the generator ( 5) has connected electrical load (28).

2. Damping device according to claim 1, characterized in that the generator (5) is formed by a permanent or self-excited motor / generator (5) which at the same time forms the motor for the electric actuator (1).

3. Damping device according to claim 1 or 2, characterized in that the electrical load (28) from the generator (5) via a rectifier circuit (27) is fed.

4. Damping device according to one of claims 1 to 3, characterized in that the electrical load (28) is adjustable in terms of its heat dissipation.

5. Damping device according to claim 4, characterized in that the electrical load (28) is assigned a damping control circuit (30) with adjusting elements (32, 33; 46, 49, 53).

6. Damping device according to claim 5, characterized in that the control circuit (30) has a current limiter setting element (53).

7. Damping device according to claim 5 or 6, characterized in that the control circuit (30) has a damping start setting element, for example an initial voltage setting potentiometer (49) in a comparison circuit (47, 48).

8. Damping device according to one of claims 5 to 7, characterized in that the control circuit (30) has an adjusting element (46) for adjusting the slope of a damping characteristic (47).

9. Damping device according to one of claims 5 to 8, characterized in that the control circuit (30) is formed by a microcomputer (μC) with at least one parameterization input (32, 33).

10. Damping device according to claim 9, characterized in that the microcomputer (μC) is connected as a subsystem to a master electronics circuit (34) providing motor-specific data.

11. Damping device according to one of claims 1 to 3, characterized in that the electrical load (28) is formed by at least one Zener diode (54).

12. Actuator with a damping device according to one of claims 1 to 11 and with non-self-locking gear elements (6, 7, 8, 9, 22).

13. Actuator according to claim 12, with a damping device according to one of claims 2 to 11, characterized in that the motor / generator (5) via an electrically operated changeover switch (25) in normal operation with a motor control circuit (26) and in the event of a fault, in the event of a power failure, with the electrical load

(28) is connected.