EP1320676A1

EP1320676A1 - Two-step electric-motor driven actuator for a valve

Info

Publication number: EP1320676A1
Application number: EP01960724A
Authority: EP
Inventors: Bjoern Hagemann; Carsten Horn
Original assignee: Berger Lahr GmbH and Co KG
Current assignee: Berger Lahr GmbH and Co KG
Priority date: 2000-09-12
Filing date: 2001-09-05
Publication date: 2003-06-25
Also published as: WO2002023032A1; DE10044898A1

Abstract

The invention relates to an exhaust gas recirculation valve (1) for a combustion engine comprising an actuating device (7) with a control unit formed by a valve shaft (8). An electric-motor driven screw drive mechanism (9) is connected to the control unit (8) for positioning the control unit over a long path with a reduced adjusting force, in addition to an electrical lift actuator (10) with a small adjustment path and a large adjusting force. Said actuators (9, 10) can be dimensioned according to the different operational requirements. According to the force required in the valve adjustment path, the lift actuator can be used with a high adjusting force and a short path for high opening forces and the screw drive mechanism (9) can be used for an exact positioning movement over a long lift path (10).

Description

TWO-STAGE ELECTRIC MOTOR ACTUATOR FOR A VALVE

The invention relates to a valve with an actuating device for opening and closing, in particular an exhaust gas recirculation valve for internal combustion engines, the actuating device being connected to an actuator of the valve. Exhaust gas recirculation valves for internal combustion engines are used to reduce the fuel consumption and emissions of diesel and gasoline engines. With the help of this valve, exhaust gases are added to the combustion air, so that a defined amount of oxygen is supplied to the combustion process. Most of the time, pneumatic actuators are used to actuate exhaust gas recirculation valves, but they only allow open / close positions of the valve, which means that no intermediate positions can be positioned.

When the valve is actuated, a considerably increased power requirement can occur to open the valve due to the pressure conditions. Deposits that lead to the valve sticking to the valve seat also increase the opening force. In contrast, the adjustment forces of the open valve are about a power of ten lower.

Because of this different adjustment force requirement, actuators with gears are known which realize a non-linear reduction, that is, higher forces for opening the valve. In addition, one knows cam drives (US 4561408), eccentric drives (US 4840350), cam drives (US 5937835), crank rod drives (US 6102016). Although this makes it possible to achieve short adjustment times, these arrangements have the disadvantage that they cannot absorb any tensile forces and so the zero position can be determined only with difficulty or is mechanically complex to build due to the number of bearing points.

Actuators with a linear gear are already known (US 6089536). This must be for the maximum Adjustment force must be dimensioned over the entire adjustment path, so that this system has a low adjustment speed for a given driving force.

An exhaust gas recirculation valve is known from DE 1 98 311 40 A1, which works with a lifting magnet. The fact that the maximum adjusting force is required at the point at which the lifting magnet develops the least force is disadvantageous here. In addition, lifting magnets with adjustment paths in the range of several millimeters have the disadvantage of a very high power requirement. Furthermore, there are disadvantages compared to gearbox arrangements when the valve is opened, since the lifting magnet tends to overshoot due to the considerable force absorption.

Although the above-mentioned actuators operated by an electric motor can be positioned in intermediate positions and have advantages over pneumatic ones with regard to the positioning accuracy and the availability of the drive energy, the disadvantages described above make these actuators still in need of improvement.

The object of the present invention is to provide a valve with an actuating device which, on the one hand, is able to actuate the valve quickly and also with a high counterforce and which also has a comparatively large one

Has adjustment path with high positioning accuracy. In addition, the energy requirement of the actuating device should be low.

To solve this problem, it is proposed that the actuating device has an electric motor-driven screw drive connected to the actuator for positioning the actuator over a long distance with a low adjustment force and a stroke actuator connected to the actuator with a short adjustment path and a large adjustment force. The actuators used can be dimensioned according to the different requirements in terms of work requirements, which on the one hand achieves a compact design and on the other hand low power consumption. Depending on the power requirement in the course of the adjustment path, the appropriate actuator can be activated. High opening forces can be overcome by the stroke actuator with a large adjustment force and a small path, while when the valve is open, the screw drive enables an adjustment and positioning movement over a long stroke distance with a low force and exact positionability.

One embodiment provides that the stroke actuator with a short adjustment path and a large adjustment force is formed by an electric stroke magnet or a piezotranslator. These stroke actuators work with a very small stroke, but this is sufficient for "detaching" for the first part of the opening path, in which a high opening force is required due to the valve sticking together and due to the gas pressure conditions. A stroke of a fraction of a millimeter, for example 100 micrometers, is sufficient to overcome the holding forces acting when the valve is closed. With this small stroke, very high adjustment forces can be applied despite the compact design. In addition, there is only a small current consumption by the actuator.

A brushless DC motor or a stepper motor is expediently provided as the drive motor for the screw drive having a spindle. In this case, drive motors of small size are sufficient, since they only have to be dimensioned in accordance with the comparatively small adjustment forces to be applied when the valve is open. This enables a compact design and high dynamics to be achieved. One embodiment provides that the actuator formed by a valve stem is rod-shaped and is rotatably connected to a rotor of the electromotive drive and to a spindle, that the stator of the electromotive drive and the stator of the stroke actuator are connected to each other and that to the spindle meshing spindle nut is connected to the core of the stroke actuator.

Another embodiment provides that the actuator is rod-shaped with a spindle which meshes with a spindle nut connected to a rotor of the electromotive drive, that the spindle nut is preferably rotationally decoupled from the core of the stroke actuator, and that the stator of the stroke actuator, the stator of the electromotive drive and a linear guide with anti-rotation for the rod-shaped actuator are connected.

Both embodiments have in common that they are compact and can therefore be used without problems even in confined spaces. Despite the compact design, both high adjustment forces and long adjustment distances with exact positioning are possible.

A format adjustment is also possible with the actuating device according to the invention, in that the lifting spindle actuator is actuated cyclically to achieve high forces over a large adjustment path. The adjustment is made gradually. When the solenoid or similar short stroke actuator is actuated, the load moves and when the short stroke actuator is reset, the spindle is adjusted.

An embodiment of the invention provides that the stroke actuator is formed by a second screw drive which, in comparison to the first screw drive for positioning the actuator over a long distance with a small adjustment force, has a short adjustment path with a large adjustment force and that the thread pitch of the second Screw drive in particular is significantly smaller than that of the first screw drive. In this embodiment, rotary, in particular electromotive drives can be used for the two screw drives. It is preferably provided that the stroke actuator formed by the second screw drive is a rotary magnet

Has drive.

A further embodiment of the actuating device according to the invention provides that the rod-shaped actuator formed by a valve stem is guided in a linear guide with anti-rotation device and is designed in sections as a spindle which meshes with a spindle nut connected to a rotor of the electromotive screw drive that preferably a lifting actuator having a rotating magnet has a threaded piece connected to its rotor with an internal thread with a small pitch, which meshes with a mating threaded piece with an external thread, which mating threaded piece is arranged in a rotationally fixed manner and is rotationally decoupled from the spindle nut or the rotor connected to it. This exemplary embodiment includes an actuating device with two electromotive screw drives.

Another, possible embodiment of an actuating device according to the invention provides that the rod-shaped actuator formed by a valve stem in a linear guide

Anti-rotation guide and sections is designed as a spindle that meshes with a spindle nut, that the spindle nut is connected via a limit force coupling to the rotor of the electromotive screw drive, which is rotatably connected to a preferably tubular internal thread part, which meshes with the spindle nut carrying an external thread and that this thread has a smaller pitch than the thread between the spindle and the spindle nut. This actuator with two different drive Transmission paths to the actuator only require a single motor drive, the decoupling of the two drive branches being provided by the limit force coupling. For a low adjustment force, the screw drive with the larger thread pitch is activated and after the occurrence of a higher load and exceeding a limit transmission force specified by the limit force coupling, the second screw drive with the smaller thread pitch is activated.

According to a further proposal of the invention, only a single motor drive also requires an actuating device in which the stroke actuator with a short adjustment path and a large adjustment force is formed by a planetary gear. The rod-shaped actuator, which is preferably formed by a valve stem, is guided in a linear guide with anti-rotation device and is designed in sections as a spindle which meshes with a spindle nut, the spindle and the spindle nut forming the screw drive and the planetary gear between the spindle nut and the rotor of the latter Screw drive is arranged. If the rotor is driven, this rotational movement is transmitted to the spindle nut via the planetary gear. As a result, the spindle nut rotates according to the reduction at low speed and, if necessary, high torque. After a certain angle of rotation, the planetary gear is blocked, so that the mechanical reduction stage formed by the planetary gear is inoperative. The spindle nut is thus directly coupled to the speed of the rotor and accordingly runs at a higher speed and a lower level of force.

The actuating device comprising the screw drive and the stroke actuator expediently has a sensor which is connected to a measuring and control device which has a switching logic for selectively actuating the screw drive or of the stroke actuator depending on the required actuation force. In particular, an angle of rotation sensor system is assigned to the electric motor drive for the screw drive. With the help of the rotation angle sensor, the zero point can be readjusted during operation and thus tolerances and thermal expansion can be compensated. In addition, the measuring and control device can detect a blocking of the spindle drive when the adjustment forces are too great for it and then use the lifting magnet or similar lifting actuator to open the valve.

A return element, preferably a return spring, is expediently provided for returning the actuator to a predeterminable position, in particular in the closed position of the valve. In the event of faults, this return spring ensures that the system is reset to a fail-save position, in the present case in particular to the valve's closed position. When the screw drive is actuated in the opening direction, the torsion spring is tensioned so that it can reposition the actuator in the initial position, ie in the closed position, in the event of faults.

Additional embodiments of the invention are listed in the further subclaims. The invention is explained in more detail below with its essential details using the drawings.

It shows:

1 shows a longitudinal sectional view of a first exemplary embodiment of an exhaust gas recirculation valve with a

Solenoid as a second stroke actuator,

2 is a longitudinal sectional view of a second embodiment of an exhaust gas recirculation valve, 3 shows a longitudinal sectional view of a third exemplary embodiment of an exhaust gas recirculation valve with a rotary magnet as the second stroke actuator,

Fig. 4 is a longitudinal sectional view of a fourth embodiment of an exhaust gas recirculation valve with a single drive and

5 shows a longitudinal sectional illustration of a fifth exemplary embodiment of an exhaust gas recirculation valve, likewise with a single drive.

An exhaust gas recirculation valve 1,1a to 1d shown in FIGS. 1 to 5 is used in an internal combustion engine to recirculate exhaust gas from the exhaust area back into the intake area for the fuel-air mixture. For this purpose, the exhaust gas recirculation valve 1, 1a to 1d is attached to a housing 2 with a return duct 3, the direction of flow of the recirculated combustion gases being identified by the arrows PF1. The return duct 3 can be closed with the aid of a valve 4 designed as a cone valve in the exemplary embodiments, the closing part 5 lying tightly against a valve seat 6 on the housing side in the closed state.

An actuating device 7 is provided for opening and closing the valve 4. The rod-shaped valve stem 8 serves as an actuator and connecting element between the closing part 5 of the valve and the actuating device 7. The actuating device 7 has an electric motor-driven screw drive 9 and an electric stroke actuator 10. The in the embodiments of FIG. 1 u. 2 designed as a solenoid 11 stroke actuator has a very short working stroke, but can transmit high forces. The screw drive, which in the exemplary embodiment is a spindle drive is designed to adjust the valve over a larger distance and also for precise positioning. Both the stroke actuator 10 and the screw drive 9 are connected to a measuring and control device, not shown here, via which the power supply and control takes place. This measuring and control device also has a switchover logic for selectively actuating either the screw drive or the stroke actuator.

The screw drive can have a brushless DC motor or a stepper motor as preferred drive motors. The rotor 12 of the screw drive motor 13 is connected in a rotationally fixed manner to the valve shaft 8 which also forms the rotor shaft. The stator 14 of the motor 13 is arranged around the rotor 12. At the upper end of the valve stem 8 it is provided with a spindle 15 which meshes with a spindle nut 16. If the motor 13 is driven so that its rotor 12 rotates, the spindle 15 moves within the spindle nut 16 in the axial direction, so that the valve can be closed or opened depending on the direction of rotation.

The lifting actuator 10 formed in the exemplary embodiment according to FIGS. 1 and 2 by an electrical lifting magnet 11 has a stator 17 and an armature or core 18 which can be moved relative thereto. The stator 17 carries a coil 19 and formed an electromagnet that attracts the core 18 when energized.

In the exemplary embodiment shown in FIG. 1, the core 18 is connected to the spindle nut 16, so that when the lifting magnet 11 is actuated, its lifting movement is transmitted via the spindle nut 16 and the spindle 15 and thus to the valve stem 8. With such a stroke movement, the valve 4 is moved in the opening direction according to the arrow PF2.

The core 18, which is fixedly connected to the spindle nut 16, is connected to the stator 17 of the lifting magnet 11 via an anti-rotation device 20 which permits the working stroke movement. The stator 17 and the stator 14 of the screw drive 9 form a stationary unit which is connected to a carrier and housing part 21 of the actuating device 7, which is also connected to the housing 2 having the return channel 3. By combining a screw drive 9 with a short-stroke actuator 10, large adjustment paths with a small force level (screw drive) and small adjustment paths with a large force level (stroke actuator) can be superimposed on one another. Both drives work together on the valve stem 8. Depending on the force required to adjust the valve closing part 5, one or the other drive can be activated. The stroke actuator 10 is designed for a very small stroke movement, which can be, for example, in the tenths of a millimeter range. Such a short working stroke is sufficient, however, to lift a closing part 5, which is stuck in the closed position due to combustion residues and the like, from its valve seat 6. As soon as this has taken place, the valve can be positioned comparatively smoothly, so that the screw drive 9 can then be switched over. An exact intermediate positioning of the closing part 5 and thus an exact adjustment of the passage cross section is then also possible. The valve can thus not only be positioned exactly between a closed position and an open position but also in any intermediate position. The stroke actuator 10 designed for a very short working stroke enables a very compact design and the screw drive 9 can be made very compact in the same way, since it only has to transmit comparatively small adjustment forces. The power supply of the electromechanical lifting magnet 11 can be supported at least by a capacitor discharge or can be formed exclusively by a capacitor discharge. Since the actuation of the solenoid 11 takes place only over a short period of time, the stored capacitor charge is sufficient for actuation in most cases. The power supply device of the lifting magnet can be dimensioned correspondingly small his .

Overall, the two approximately coaxially arranged drives working together on the valve stem 8 can be accommodated in a small carrier and housing part 21.

A drive-less DC motor is provided as the drive motor 13 for the screw drive 9 in the exemplary embodiment according to FIGS. 1 and 2, which is equipped with a rotation angle sensor system 22 and enables exact positioning. For the opening or closing movement of the valve 4, the rotor 12, 12a of the screw drive motor 13 executes a rotary movement over a few revolutions depending on the design of the spindle transmission. For the motor 13, a so-called can motor with ring coils, which can be mass-produced inexpensively, can be used. Motors of this type are also used for small synchronous motors or for stepper motors.

The screw drive motor of the screw drive shown in FIG. 2 is also equipped with such a motor, a rotor 12a having a somewhat modified design being used here.

The rotor 12 (FIG. 1) connected to the rotatable valve stem 8 is designed to be somewhat longer than the stator because of the axial stroke adjustment in order to achieve an overlap of the stator and rotor in every position position.

A return spring 23 is arranged between the rotor 12 and the core 18 of the lifting magnet 11, which core is fixed in the direction of rotation. Starting from the closed position of the valve so these, embodied as a rotational return spring spring 23 is biased so that is in the ^'fault case, the spring-stored energy for closing the valve available. The return spring 23 thus forms a fail-save spring. The exhaust gas recirculation valve 1a according to FIG. 2 is basically constructed in the same way as the exhaust gas recirculation valve 1 according to FIG. 1 and accordingly also has a screw drive 9 and a short stroke actuator 10 in the form of a lifting magnet 11. The main difference is that the mechanical construction according to FIG. 2 is designed in such a way that the valve 4 with the closing part 5 and the valve stem 8 do not rotate when the stroke is adjusted. In this embodiment, the valve stem 8 is guided axially in an anti-rotation device 24, which is arranged when the valve stem 8 passes through an opening in the carrier and housing part 21.

The section of the valve stem 8 passing through the drive area is designed as a spindle 15a and meshes with a spindle nut 16a which is connected in a rotationally fixed manner to the rotor 12a of the screw drive motor 13.

The spindle nut 16a is supported by a roller bearing 25 on the core 18 of the solenoid 11. As a result, the valve stem 8 can be moved back and forth when the spindle nut 16a rotates in accordance with the double arrow Pf3 and when the solenoid 11 is actuated, the stroke movement of the core 18 is transmitted via the roller bearing 25 to the spindle nut 16a, which in turn transmits this stroke movement to the spindle 15a or transmits the valve stem 8. In this case, the valve stem 8 and the closing part 5 connected to it perform a lifting movement according to the arrow Pf2 in the opening direction of the valve.

In the embodiment according to FIG. 2 there is also a superimposed short stroke movement by the lifting magnet 11 and a positioning movement with a larger adjustment path by the screw drive 9. In the embodiment according to FIG. 2, the fail-save return spring 23 is arranged between the non-rotatable valve stem 8 or a closing part 26 located at its spindle end and the spindle nut 16a rotating during a stroke adjustment by the screw drive 9. 3 and 4 show exhaust gas recirculation valves 1b, 1c which have actuating devices 7 with two screw drives. The first screw drive 9a or 9b is designed for positioning the actuator 8 over a long distance with a low adjustment force, while the second screw drive 27 (FIG. 3) or 28 (FIG. 4) forming the stroke actuator 10 is designed for a short adjustment path with a large adjustment force This is achieved in that the thread pitch of the second screw drive 27 or 28 is significantly smaller than that of the first screw drive 9a or 9b.

3 shows an exhaust gas recirculation valve 1b, in which the actuating device 7 has two screw drives with different thread pitches. The valve stem 8 is formed at its inner end as a spindle 15b which meshes with a spindle nut 16b connected to the rotor 12b of the first screw drive 9a.

The second screw drive 27 has a rotary magnet 29 as the drive, the rotor 30 of which is connected to a threaded piece 31, which carries an internal thread 32 with a small pitch. The threaded piece 31 meshes with its internal thread 32 with a counter-threaded piece 33 with an external thread that is arranged in a rotationally fixed and coaxial manner. The counter-thread piece 33 is rotationally decoupled from the spindle nut 16b or the rotor 12b connected to it. For this purpose, a roller bearing 34 is arranged between the rotor 12b and the counter-thread piece 33, via which a pressure transmission is possible. For the rotationally fixed mounting of the counter thread piece 33, this can engage with a radially inwardly projecting nose in an outer longitudinal groove of the spindle 15b.

If the rotary magnet 29 is actuated, the threaded part 31 connected to the rotor 30 is rotated. The non-rotatable but longitudinally displaceable counter-threaded part 33 is thereby moved towards the rotor 12b and displaces it via the roller bearing 34. This movement is transmitted via the spindle nut 15b to the valve stem 8, so that a lifting movement takes place according to the arrow Pf2. Due to the small pitch of the thread 32 between the threaded piece 31 and the counter-threaded piece 33, a high force can be applied in the direction of the arrow Pf 2, which is provided for the first opening movement when the valve is closed.

For the further adjustment movement of the valve, the first screw drive 9a can be activated, so that the rotor 12b drives the spindle nut 16b and thereby moves the valve stem either in the opening or closing direction. If the rotary magnet 29 is not activated, it is brought back to its original starting position by a return spring 35. As in the other exemplary embodiments, a fail-save return spring 23 is also provided here, by means of which the valve can be brought into the closed position in the event of faults.

FIG. 4 shows an embodiment of an exhaust gas recirculation valve 1c, in which the actuating device 7, like the exemplary embodiment according to FIG. 3, has two screw drives with threads of different pitch. The valve stem 8, which is longitudinally guided by an anti-rotation device 24, also has a section here with a spindle 15c which meshes with a spindle nut 16c.

The spindle nut 16c is connected to the rotor 12c of the electromotive screw drive 9c via a limit force coupling 36. When the rotor 12c rotates, the spindle nut 16c is thus taken along via the limit force coupling 36 and the valve stem 8 is thereby moved in the closing or opening direction.

The spindle nut 16c has an external thread 37 which meshes with a tubular internal thread part 38 which is connected to the rotor 12c in a rotationally fixed manner. The limit force of the limit force coupling arranged between the rotor 12c and the spindle nut 16c 36 exceeded, a relative rotational movement occurs between the internal thread part 38 connected to the rotor 12c and the spindle nut 16c. The thread 37 engaged therebetween has a smaller pitch than the thread between the spindle 15c and the spindle nut 16c, so that in this operating situation a greater driving force acts on the valve stem 8 with a small adjustment path.

In the exemplary embodiment, the limit force coupling 36 is formed by a rotationally prestressed spring which engages at one end on the spindle nut 16c and at the other end on the rotor 12c or the internal thread part 38 connected to it. A stop 39 serves to limit the relative rotation between the spindle nut 16c and the rotor 12c which is caused by the prestressed spring. If the pressure force present by the prestressed spring at the stop 39 is overcome, then a relative rotational movement occurs between the internal thread part 38 and the spindle nut 16c, so that the thread 37 located therebetween provides for a lifting movement of the valve stem 8. This operating case occurs when a certain overload is present, which can occur in particular when the valve is opened for the first time. If this overload is overcome, the screw drive 28 is returned to its original position up to the stop 39 with a slight pitch by the rotationally prestressed spring 40. The particular advantage of the embodiment of the actuating device 7 shown in FIG. 4 is that only a single motor 13a is required for both screw drives 27, 28. In this embodiment, too, a rotation angle sensor system 22 and a fail-save return spring 23 are provided.

5 shows an exhaust gas recirculation valve 1d with an actuating device 7, which has a screw drive 9d and a stroke actuator 10 formed by a planetary gear 41 with a short adjustment path and a large adjustment force. The valve stem 8 is guided so as to be longitudinally displaceable in a linear guide with anti-rotation device 24 and is designed in sections as a spindle 15d which meshes with a spindle nut 16d.

The motor 13b has a rotor 12d which is connected in a rotationally fixed manner to a ring gear 42 which is partially internally toothed.

The planetary gear 41 is arranged between the rotor 12d and the spindle nut 16d. For this purpose, the ring gear 42 meshes with a planet gear 43 which is connected to the spindle nut 16d and which meshes with a fixed sun gear 44 arranged coaxially to the spindle nut 16d. Between the rotor 12d and the spindle nut 16d, a limited rotation allowable rotation stop 45 is provided.

If the rotor 12d is driven, this rotational movement is transmitted to the spindle nut 16d via the ring gear 42 and the planet gear 43. As a result, the spindle nut rotates according to the reduction at low speed and, if necessary, high torque. This operating state is used for small adjustment paths with a high level of force. After a certain angle of rotation, for example 40 °, the rotary stop 45 blocks the orbital movement of the ring gear 42, so that the mechanical reduction stage formed by the planetary gear 41 is inoperative. The spindle nut is thereby directly coupled to the speed of the rotor 12d and accordingly runs at a higher speed than when the planetary gear is interposed. This results in an increased adjustment speed for the valve stem 8 with a low level of force. Due to the friction, the planetary stage is activated when the direction of rotation is reversed, so that a high level of force is available to open valve 4. The spindle nut 16d can be connected to the rotor 12d via a limit force coupling formed by a torsion spring. This torsion spring results in a mechanical preload, by means of which the planetary stage is only used in one direction of rotation from a certain force level. Without such a spring preload, the combination of planetary gear and spindle drive can also be used to increase resolution and dynamics. In this case, the target position can be quickly pre-positioned with a coarse resolution and finely positioned by reversing the direction of rotation using the planetary gear stage.

Claims

Expectations

1. Valve with an actuating device (7) for opening and closing the valve, in particular exhaust gas recirculation valve for internal combustion engines, wherein the actuating device (7) is connected to an actuator (8) of the valve, characterized in that the actuating device (7) one with the Actuator (8) connected, electromotively driven screw drive (9, 9a to 9d) for positioning the actuator (8) over a long way with low adjustment force and a stroke actuator (10) connected to the actuator with a short adjustment path and large adjustment force.

2. Valve according to claim 1, characterized in that a brushless DC motor or a stepping motor is provided as the drive motor (13) for the screw drive (10) having a spindle.

3. Valve according to claim 1 or 2, characterized in that the stroke actuator (10) with a short adjustment path and a large adjustment force is formed by an electric solenoid (11) or a piezo translator.

4. Valve according to claim 1 or 2, characterized in that the stroke actuator (10) is formed by a second screw drive (27, 28) which, in comparison to the first screw drive (9), for positioning the actuator (8) over a long time Path with low adjustment force, has a short adjustment path with large adjustment force and that the thread pitch of the second screw drive (27, 28) is in particular considerably smaller than that of the first screw drive.

5. Valve according to claim 4, characterized in that the stroke actuator (10) formed by the second screw drive (27) has a rotary magnet (29) as the drive.

6. Valve according to one of claims 1 to 3, characterized in that the preferably formed by a valve stem (8) actuator is rod-shaped and with a rotor (12) of the electromotive drive and with a spindle (15) is rotatably connected that the stator (14) of the electromotive drive (9) and the stator

(17) of the stroke actuator (10) are connected to each other and that the spindle nut (16) meshing with the spindle (15) is connected to the core (18) of the stroke actuator (10).

7. Valve according to one of claims 1 to 3, characterized in that the preferably formed by a valve stem (8) actuator is rod-shaped with a spindle (15a) which with a rotor (12a) of the electromotive screw drive (9) connected spindle nut (16a) that meshes the spindle nut (16a) with the core

(18) of the stroke actuator (10) is preferably connected in a rotationally decoupled manner and that the stator (17) of the stroke actuator (10), the stator (14) of the electromotive screw drive (9) and a linear guide with anti-rotation device (24) for the rod-shaped actuator (8 ) are connected.

8. Valve according to one of claims 1 to 7, characterized in that the screw drive (9) for positioning the actuator (8) over a long way with low adjustment force and the stroke actuator (10) with a short adjustment path and large adjustment force coaxially in a support and housing part (21) are arranged.

9. Valve according to one of claims 1 to 5, characterized in characterized in that the rod-shaped actuator, which is preferably formed by a valve stem (8), is guided in a linear guide with anti-rotation device (24) and is designed in sections as a spindle (15b), which is equipped with a rotor 5 (12b) of the electromotive screw drive (9a) connected spindle nut (16b) that the stroke actuator (10), which preferably has a rotary magnet (29), has a threaded piece (31) connected to its rotor (12b) with an internal thread (32) of low pitch, which has, 10 a counter-threaded piece (33 ) meshes with external thread, which

Counter thread piece is arranged non-rotatably and is rotationally decoupled from the spindle nut (16b) or the rotor (12b) connected to it.

15 10. Valve according to claim 9, characterized in that the counter-threaded piece (33) of the stroke actuator (10) in a coaxially arranged rotor (12b) of the electromotive screw drive (9) supported roller bearing (34) is supported.

20

11. Valve according to claim 9 or 10, characterized in that the rotor (30) of the rotary magnet (29) is acted upon by a return spring (35) against the drive direction.

25

12. Valve according to one of claims 1 to 4, characterized in that the rod-shaped actuator, preferably formed by a valve stem (8), is guided in a linear guide with an anti-rotation device (24) and is designed in sections as a spindle (15c), which with a spindle nut

(16c) meshes that the spindle nut (16c) is connected via a limit force coupling (36) to the rotor (12c) of the electromotive screw drive (9c), which is rotationally fixed with a preferably tubular internal thread part (38) is connected which meshes with the spindle nut (16c) carrying an external thread (37) and that this thread (37) has a smaller pitch than the thread between the spindle (15c) and the spindle nut (16c).

13. Valve according to claim 12, characterized in that the limit force coupling (36) between the screw drive (9c) for positioning over a long distance with low adjustment force and the stroke actuator (10) with a short adjustment path and large adjustment force by means of a rotationally prestressed spring (40 ) is formed, which acts on the one hand on the spindle nut (16c) and on the other hand on the internal thread part (38) connected to the rotor (12c).

14. Valve according to claim 12 or 13, characterized in that a stop (39) is provided between the spindle nut (16c) and with the rotor (12c) of the electromotive screw drive (9c) or the associated internal thread part (38) for limitation the rotational preload.

15. Valve according to one of the preceding claims, characterized in that the stroke actuator (10) with a short adjustment path and large adjustment force is formed by a planetary gear (41).

16. Valve according to claim 15, characterized in that the rod-shaped actuator, preferably formed by a valve stem (8), is guided in a linear guide with an anti-rotation device (24) and is designed in sections as a spindle (15d) which is provided with a spindle nut (16d ) meshes that the spindle (15d) and the spindle nut (16d) forms the screw drive (9d) and that the planetary gear (41) between the spindle nut (16d) and the rotor (12d) this Screw drive (9d) is arranged.

17. Valve according to claim 15 or 16, characterized in that the rotor (12d) of the screw drive (9d) is partially formed as a ring gear which meshes with at least one, with the spindle nut (16d) connected planet gear (43) that coaxially Spindle nut is a fixed sun gear (44) is arranged, which is in engagement with the one or more planet gears (43) and that between the spindle nut (16d) and the rotor (12d) a limited

Rotation stop (45) permitting rotation is provided.

18. Valve according to one of claims 15 to 17, characterized in that the spindle nut (16d) via a limit force coupling with the rotor of the electromotive

Screw drive (9d) is connected, and that the limit force coupling preferably has a torsion spring.

19. Valve according to one of the preceding claims, characterized in that between the stator (17) and the core

(18) of the lifting actuator (10) formed by a lifting magnet (11) is arranged to prevent rotation (20).

20. Valve according to one of the preceding claims, characterized in that between the stator (17) and the core

(18) of the lifting actuator (10) formed by a lifting magnet (11) is arranged a return spring.

21. Valve according to one of claims 1 to 20, characterized in that the screw drive (9, 9a, 9b) and

Stroke actuator (10) having an actuating device (7) has a sensor (22) which is connected to a measuring and control device which has a switchover logic for selectively actuating the screw drive (9, 9a, 9b) or the stroke actuator (10) depending on the required actuation force.

22. Valve according to claim 21, characterized in that in the screw drive electric motor (13, 13a, 13b) one

Angle of rotation sensor system (22) is arranged.

23. Valve according to one of claims 1 to 22, characterized in that a return element, preferably a return spring (23) is provided for returning the actuator (8) in a predeterminable position, in particular in the closed position of the valve (4).

24. Valve according to one of the preceding claims, characterized in that the power supply of the stroke actuator (10), which is preferably formed by an electromechanical lifting magnet (11) or a rotary magnet (29), is supported at least by a capacitor discharge or is provided exclusively by a capacitor discharge.