FAIL-SAFE ACTUATOR AND ASSEMBLY UNIT

Abstract

A fail-safe actuator for moving a part has in each case a drive (18, 118) by means of which a first or a second drive train (24, 26) can be moved. The drive trains (24, 26) in each case have their own output shaft (34, 38) and can be actuated independently of one another. An energy storage device is coupled with the second output shaft (38), wherein a holding device selectively holds the energy or releases it from the energy storage device, so that the second output shaft (38) can be moved. A rotary entrainment of the first output shaft (34) ensures that in the event of a failure of the drive (18) this is moved into a specified end position. The two output shafts (34, 38) are set in motion via gear wheels (32, 36) if the drive trains are actuated. An assembly unit consisting of actuator and moved part is also described.

Claims

1. A fail-safe actuator (10) for moving a part (12) between two end positions, comprising: a first drive (18), a first drive train (24) which can be set in motion by the first drive (18) which has a first output shaft (34) which transmits the movement of the actuator outwards in the direction of the part (12), a second drive (118), a second drive train (26) which can be set in motion by the second drive (118) which has a second output shaft (38) which runs coaxially with the first output shaft (34), wherein the first or the second drive (18, 118) can be activated, selectively, in order to set the first or second output shaft (34, 38) in motion, an energy storage device (16) which is coupled with the second drive train (26), at least one externally actuatable holding device (182) which ensures, selectively, that the energy stored in the energy storage device (16) remains in the energy storage device (16) or is released to the second drive train (26), a mechanical rotary entrainment device (40) between the second output shaft (38) and the first output shaft (34) which is configured such that it permits a rotation of the first output shaft (34) relative to the second output shaft (38) by at least one angle of rotation which is associated with a distance between the two end positions if the energy storage device (16) is not released and if the first drive (18) moves the first output shaft (34) between the two end positions and provides a rotary entrainment of the first output shaft (34) by the second output shaft (38) with the energy storage device (16) released and the first drive (18) when failed in a first of the two end positions.

2. A fail-safe actuator (10) according to claim 1, wherein both the first and second drives (18, 118), the rotary entrainment device (40) and the at least one holding device (182) are configured and controllable in a coordinated manner such that, in a first state, the second drive (118) moves the second output shaft (38) in the direction of a second of the two end positions and energy is thereby introduced into the energy storage device (16), in a subsequent second state, the at least one holding device (182) holds the energy in the energy storage device (16) and the first drive (18) can move the part (12) between its end positions, in a subsequent third state, in which both the first and second drives (18, 118) fail, the holding device (182) releases the energy in the energy storage device (16) and as a result the second output shaft (38) is moved in the direction of the first end position and a rotary entrainment of the first output shaft (34) in the direction of the first position is made possible.

3. A fail-safe actuator (10) according to claim 2, wherein in the first state, both the first and second drives (18, 118) drive and both the first and second output shafts (34, 38) move in the direction of the second of the two end positions and energy is thereby introduced into the energy storage device (16), or that, in the first state, on the first output shaft (34) being driven in the direction of the second of the two end positions by the first drive (18), with the second drive (118) inactive, with discharged energy storage device (16) and enabled holding device (182), the first output shaft (34) carries the second output shaft (38) with it.

4. A fail-safe actuator (10) according to claim 1, wherein the holding device (182) holds the second output shaft (38) in the second state and thus holds the energy storage device (16) in the state in which the energy remains in the energy storage device (16).

5. A fail-safe actuator (10) according to claim 1, wherein each drive train is assigned its own holding device (82, 182), wherein the holding device of the first drive train is activated if the part (12) is to be held in a position.

6. A fail-safe actuator (10) according to claim 1, wherein the energy storage device (16) is coupled directly or indirectly with the second output shaft and can be detached therefrom in a non-destructive manner.

7. A fail-safe actuator (10) according to claim 6, wherein the rotary entrainment device (40) is configured such that the second output shaft (38) can entrain the first output shaft (34) in opposite directions of rotation, wherein the direction of rotation is dependent on the direction of rotary effect of the energy storage device (16).

8. A fail-safe actuator (10) according to claim 7, wherein the energy storage device (16) can be coupled to the second output shaft (38) in two different positions, and in a first position ensures that the first output shaft (34) can be pressed into one end position and in a second position can be pressed into the opposite end position.

9. A fail-safe actuator (10) according to claim 8, wherein the first position differs from the second position in that the energy storage device (16) is inverted by 180° and is thus coupled to the second output shaft (38) on the rear side.

10. A fail-safe actuator (10) according to claim 1, wherein the first and the second output shaft (34, 38) are coupleable in the direction of rotation by means of stop surfaces (90, 92, 94, 96) which come into contact with one another.

11. A fail-safe actuator (10) according to claim 10, wherein the stop surfaces (90, 92, 94, 96) are formed on opposite end faces (42, 44) of gear wheels (32, 36) or the output shafts (34, 38).

12. A fail-safe actuator (10) according to claim 10, wherein if stop surfaces (90, 94; 92, 96) of both the first and also the second drive train (24, 26) are in contact with one another, the stop surfaces which are not in contact with one another are distant from one another by at least 180°.

13. A fail-safe actuator (10) according to claim 1, wherein the energy storage device (16) comprises at least one elastic spring element.

14. A fail-safe actuator (10) according to claim 13, wherein several spring elements arranged symmetrically around the second output shaft are provided.

15. A fail-safe actuator (10) according to claim 14, wherein the compression springs (66, 68, 70, 72) are coupled mechanically to the second output shaft (38) in pairs by means of the same rack (64).

16. A fail-safe actuator (10) according to claim 15, wherein the second output shaft (38) is connected with the energy storage device (16) via a gear wheel (62) which in turn meshes with the gear teeth on the rack (64).

17. A fail-safe actuator (10) according to claim 13, wherein the energy storage device (16) is designed as a separate, externally closed assembly unit in which several spring elements are housed and which has a coupling point (60) with the second output shaft (38) which is accessible from opposite sides.

18. A fail-safe actuator (10) according to claim 1, wherein both drives (18, 118) can be operated as generators in order to brake a movement in at least one of the drive trains (24, 26).

19. An assembly unit with an actuator (10) according to claim 1 and a part (12) moved by the actuator (10) which is a valve flap or ventilation flap.

20. A fail-safe actuator (10) for moving a part (12) between two end positions, comprising: a first drive (18), a first drive train (24) which can be set in motion by the first drive (18) which has a first output shaft (34) which transmits the movement of the actuator outwards in the direction of the part (12), a second drive (118), a second drive train (26) which can be set in motion by the second drive (118) which has a second output shaft (38) coaxial with the first output shaft (34), wherein the first or the second drive (18, 118) can be activated, selectively, in order to set the first or second output shaft (34, 38) in motion, at least one spring (70 or 72) coupled with the second drive train (26); a lock which ensures, selectively, that the energy stored in the plurality of springs (70, 72) remains therein or is released to the second drive train (26), a selective coupling between the second output shaft (38) and the first output shaft (34) configured to permit a rotation of the first output shaft (34) relative to the second output shaft (38) by at least one angle of rotation which is associated with a distance between the end positions if the at least one spring is not released and if the first drive (18) moves the first output shaft (34) between the end positions and provide a rotary entrainment of the first output shaft (34) by the second output shaft (38) with at least one spring (70 or 72) and the first drive (18) when failed in a first of the two end positions.

Description

[0049] Further features and advantages of the invention are explained in the following description and in the following drawings, to which reference is made. In the drawings:

[0050] FIG. 1 shows a perspective view of an embodiment of the actuator according to the invention and the assembly according to the invention,

[0051] FIG. 2 shows a schematic view of a part of the actuator together with an energy storage device, with the outer housing omitted,

[0052] FIG. 3 shows a perspective view of the actuator according to the invention with a cut-away view of the energy storage device,

[0053] FIG. 4 shows a schematic perspective view, partially transparent, with the rotary entrainment device used with the actuator according to the invention,

[0054] FIG. 5 shows a schematic view of the rotary entrainment device, in which the first output shaft is in or close to a first end position and the energy storage device is loaded,

[0055] FIG. 6 shows a view of the rotary entrainment device shown in FIG. 5, in which the first output shaft is in an opposite, second end position,

[0056] FIG. 7 shows a view of the rotary entrainment device shown in FIG. 5 with the energy storage device acting in the opposite direction to the embodiment shown in FIG. 5, before loading of the energy storage device,

[0057] FIG. 8 shows a view of the rotary entrainment device shown in FIG. 7 with a loaded energy storage device, and

[0058] FIG. 9 shows a view of the rotary entrainment device shown in FIG. 7 with the first output shaft in a first end position.

[0059] FIG. 1 shows an assembly with a fail-safe actuator 10 which can move a part 12, for example a valve or a ventilation flap, between two end positions.

[0060] The actuator has a multiple-part outer housing 14 and an energy storage device 16 flanged or, more generally, fastened to the outer housing 14 which is designed as a separate, externally closed assembly unit.

[0061] A first and a second electrical drive 18, 118, which can be seen in FIG. 2, are housed in the outer housing 14.

[0062] A transmission 22 comprising a first drive train 24 and a second drive train 26 is driven via the drives 18, 118, wherein the first drive train 24 is assigned to the drive 18 and the second drive train 26 is assigned to the drive 118.

[0063] The drive trains 24, 26 comprise gear wheels which convert the torque generated by the drive 18, 118 and pass it on into their drive train.

[0064] Each drive train 24, 26 can be fixed by a separate holding device assigned thereto. The drive train 24 has a holding device 82 which is designed in the form of an electromagnetic brake and acts on a gear wheel which is driven directly by the pinion of the drive 18. This means that the holding device 82 only needs to hold a very low torque and requires a small power input, so that it can be of compact construction and only exhibits low intrinsic heating. The same also applies to a holding device 182 which is provided for the second drive train 26 and likewise acts directly on a gear wheel which is also driven directly by the pinion of the drive 118.

[0065] The first drive train 24 has a first gear wheel 32 which is coupled with a first output shaft 34 or rests thereon. The second gear wheel 36, arranged parallel to the first gear wheel 32, is assigned to the second drive train 26 and is also coupled with a second output shaft 38 or forms part of same.

[0066] The output shafts 34, 38 are arranged coaxially with one another and terminate in the gear wheels 32, 36.

[0067] The first output shaft 34 leads, directly or with the interposition of other mechanical torque-transmitting parts, to the driven part 12.

[0068] Illustrated in FIG. 4 is a mechanical rotary entrainment device 40 between the first output shaft 34 and the second output shaft 38. The rotary entrainment device 40 is realised by means of opposing end faces 42, 44 of the gear wheels 32, 36, wherein stop surfaces are provided here via which the output shafts 34, 38 can be coupled in the direction of rotation.

[0069] In the illustrated example, the stop surfaces are formed by projections, more precisely pins, which are fastened to the gear wheels 32, 36 and project axially in relation to these.

[0070] Specifically, on the gear wheel 36, a pin 46 and a pin 48 are introduced into corresponding axial openings.

[0071] These pins 46, 48 are arranged on the same circular diameter around the imaginary central axis of the output shafts 34, 38. A pin 50 is fastened to the gear wheel 32, likewise in that it is introduced, preferably pressed, into a corresponding axial opening. It too is arranged on the same circular diameter as the pins 46, 48.

[0072] Optionally, the pin 50 has on opposite sides in a circumferential direction in each case an indentation 52 which is complementary to the outer diameter or the outer geometry of the pins 46, 48, so that when the pin 50 comes into contact with the pin 46 and the pin 48, not only a linear contact but a planar contact takes place in each case.

[0073] It can also be seen in FIG. 4 that the second output shaft 38 is relatively long and has a fitting spring groove 54 via which it is coupled with the energy storage device 16.

[0074] This energy storage device 16 is shown in a cut-away state in FIG. 3.

[0075] The energy storage device 16 has a so-called coupling point 60, which is also shown in FIG. 1, which is designed in the form of a hub. The second output shaft 38 can be introduced into this hub.

[0076] The hub is torque-coupled with a gear wheel 62 which is illustrated in FIG. 3.

[0077] This gear wheel meshes with two diametrically opposing gear racks 64. Each gear rack 64 has a pair of compression springs 66, 68 or 70, 72 assigned thereto, by means of which return energy can be stored which, in the event of a failure of the drive 18, ensures that the part 12 is moved into a specified end position, even if the part 12 is positioned at a distance therefrom.

[0078] The upper gear rack 64 shown in FIG. 3 has on its right-hand end a spring plate 74 fastened thereto which rests against the right-hand end of the compression spring 68. The left-hand end of the compression spring 68 is supported against the side of the housing.

[0079] The left-hand end of the upper gear rack 64 likewise carries a spring plate 76 which rests against the right-hand end of the compression spring 66, wherein here too the left-hand end of the compression spring 66 is supported against the side of the housing.

[0080] The lower gear rack 64 as shown in FIG. 3 has loaded its assigned compression springs 70, 72 in the contrary direction. The spring-rack arrangement as a whole is point-symmetrical with respect to the central axis of the output shafts 34, 38. This means that the lower gear rack 64 has a spring plate 78 which is fastened thereto and which rests against the left-hand end of the compression spring 70, whereas the right-hand end of the compression spring 70 is supported against the side of the housing. The right-hand end of the lower gear rack 64 is coupled with a spring plate 80 which rests against the left-hand end of the compression spring 72, wherein the right-hand end of the compression spring 72 is in turn supported against the side of the housing.

[0081] If the second output shaft 38 is moved in an anticlockwise direction, as a result of which the gear wheel 62 is likewise moved in an anticlockwise direction, the upper gear rack 64 moves to the left and tensions its compression springs 66, 68 and the lower gear rack 64 moves to the right and tensions its compression springs 70, 72.

[0082] The energy storage device 16 only acts in one direction, i.e. in this installed case on relaxation of the compression springs it would cause a rotation of the second output shaft 38 in a clockwise direction.

[0083] The coupling point 60 formed by the hub can be coupled to the second output shaft 38 from two opposite sides. If the lower side of the energy storage device 16, as seen in FIG. 1, is the front side, then the upper side shown in FIG. 1 is the rear side. If the energy storage device 16 is pulled upwards off the second output shaft 38 and inverted by 180°, it can be plugged back onto the output shaft 38 with its rear side. However, as a result of this inversion of the energy storage device 16, the direction of rotation in which the energy storage device 16 acts on the second output shaft 38 is reversed. The energy storage device 16 then tries to rotate the output shaft 38 in an anticlockwise direction.

[0084] If the coupling of the energy storage device 18 to the output shaft 38 is effected by means of a fitting spring, in this case the energy storage device 16 simply needs to be additionally rotated by 180° around the central axis of the output shaft 38, since as a result of the inversion the groove for the fitting spring will change to the diametrically opposite side.

[0085] In order to hold the energy in the energy storage device 16 and thus store it, the so-called holding device 182 which is externally actuatable by means of a control (see FIG. 2) is provided which, alternatively to the aforementioned electromagnetic brake, is for example a magnetic spring lock or a clamped or form-fitting connection of some kind. In the actuated state this holding device 182 prevents a rotation of the second output shaft 38, so that the compression springs 66, 68, 70, 72 remain in their tensioned position.

[0086] The pre-tensioning of the compression springs can be varied by means of adjustment screws 86, see FIG. 3, since the spring plates 74, 76, 78, 80 can be adjusted axially relative to the gear racks 64 by means of these adjustment screws 86, because by means of these adjustment screws 86, which are screwed more or less deeply into the end face of the gear racks 64, they are spaced at a greater or lesser distance away from this. Nuts 88 are provided on the adjustment screws 86 as stops for the spring plates 74, 78. For the spring plates 76, 80, the screw heads themselves act as stops.

[0087] The adjustment by means of the adjustment screws 86 is also important because the output shaft 34 may not always be in the respective end position exactly at the end its maximum movement; otherwise slight gaps could result due to tolerances or external influences. Rather, the output shaft 34 may theoretically need to be able overrun the respective end position by a couple of degrees, so that for example a valve flap with a low pre-tension lies securely against the valve seat. These respective end positions can be different. For example, ball valves do not need to be over-rotated as far as flaps.

[0088] FIG. 5 shows the second gear wheel 36 and the fitting spring groove 54, which is naturally offset axially in relation to the gear wheel 36, and is only drawn in to make clear the position of the second output shaft 38.

[0089] Important are on the one hand the positions of the pins 46, 48, 50 relative to one another and the fact that the two gear wheels 32, 36 in each case possess gear teeth over more than 180° of the outer circumference, such as gear teeth extending around the entire circumference, that is over 360°.

[0090] The pins 46, 48 of the gear wheel 36 are spaced apart from the central axis by a greater angle α, which is so great that the stop surfaces 90, 92 of the pins 48 or 46, which face one another around the circumference, are spaced at a distance of at least 220°. This angle is the angle β. As can be seen in FIG. 5, if it is able to rotate to a maximum extent around the central axis relative to the pins 46, 48 without limitation by the moved part; the pin 50 can thus move within an angular range of more than 180° relative to the pins 46, 48, in this case in a clockwise direction, and in an anticlockwise direction with reference to FIG. 5.

[0091] In the position of the pin 48 represented in FIG. 5 with broken lines, the second output shaft 38 is rotated by 90° or somewhat more than 90° in a clockwise direction relative to the position not represented with broken lines. In this position, the energy storage device 16 is almost empty and now only has a low torque which it can apply to the first output shaft 34.

[0092] The functional principle of the actuator is explained in the following starting out from this starting position indicated with broken lines.

[0093] In a first state, the drive 18 engages, wherein at the same time its holding device 82 and the holding device 182, which were previously closed, are opened, so that on subsequent actuation of the drive 18 the complete second drive train 26 is activated. The second output shaft 38 is moved in an anticlockwise direction from the first end position represented with broken lines (see pin 48 with broken lines in FIG. 5) into the opposite second end position according to the arrow in FIG. 5, in that the driven pin 50 entrains the pin 48 in an anticlockwise direction. This means that the gear wheel 32 carries the gear wheel 36 and thus the output shaft 38 along with it. Thus, the gear wheel 62 and also the gear racks 64 are moved in an anticlockwise direction, so that the compression springs are tensioned. The holding device 182 is then actuated in order to block the second drive train 26 and thus the second output shaft 38. The pins 46, 48 thus remain in the position shown in FIG. 5.

[0094] During these movements, the first drive 18 can remain passive, and its holding device 82 remains closed.

[0095] In a subsequent second state, in which the holding device 82 is activated as before, the first drive 18 is activated and with it the first drive train 24. The gear wheel 32 is thus driven, such that the first output shaft 34 can be moved between a first end position and a second end position which is represented in FIG. 6. As a result, one or more valves or flaps, for example ventilation flaps in a tunnel, are opened and closed. The first end position can be the position which is represented in FIG. 5 or can lie even further in a clockwise direction, for example at three or around four o'clock. In this second state, the coupling 30 is released, i.e. no movement of the gear wheel 36 and thus of the output shaft 38 takes place in the second drive train. The drive trains 24, 26 are consequently decoupled from one another.

[0096] If, in a third state, the drives 18, 118 fail, for example due to a power failure or defect, a predefined position of the part 12 must be ensured. In this case the holding devices 82, 182 are released automatically, because in this case for example a spring-loaded magnet is no longer supplied with power, so that the spring removes and releases a corresponding part from engagement in the assigned drive train 24, 26. The energy is then abruptly released from the energy storage device 16. That is to say, in the event that, as shown in FIG. 6 for example, the part 12 is in a closed state and the pin 50 is located between its second end position and thereby rests against the pin 48, the gear wheel 36 rotates in a clockwise direction, as a result of which the pin 48 entrains the pin 50 and thus the first output shaft 34 and moves the part 12 into its first end position.

[0097] The loading of the energy storage device 16 or, more generally, the introduction of energy into the energy storage device 16 in the first state can also be achieved otherwise than as explained above. For this purpose the drives 18, 118 are simply actuated differently.

[0098] For example, in the first state both drives 18, 118 are actuated, so that both drive trains 24, 26 are activated and both output shafts 34, 38 are set in rotation separately from one another. Both holding devices 82, 182 are naturally thereby open. The pin 50 thus no longer needs to carry with it the pin 48, as explained above with reference to FIG. 5. The pins 48, 50 can thus be spaced apart one another in the first state by an angle of rotation, and nonetheless the pin 48 is moved into the position shown in FIG. 6, and at the same time energy is transferred into the energy storage device 16.

[0099] According to a further option, in the first state only the second drive train 26 is actuated, i.e. the drive 118 moves the second output shaft 38 in an anticlockwise direction, as seen in FIGS. 5 and 6 and thus introduces energy into the energy storage device 16. The position of the pin 50 remains unchanged in this state.

[0100] If the direction of rotation of the energy storage device 16 is to be changed, for example because in the event of a power failure the part 16 should no longer be in the open position but rather in the closed position, the energy storage device 16 is pulled off after it is completely or virtually completely discharged and, after being inverted and then rotated by 180° around the central axis of the coupling point 60, plugged back onto the second output shaft 38.

[0101] However, before fitting the inverted energy storage device 16, the second gear wheel 36 is rotated by 180° in an anticlockwise direction. The pin 46 then rests against the pin 50. This rotation of the second gear wheel 36 by 180° can be seen from the position of the fitting spring groove 54 in FIG. 7.

[0102] In order to recharge the energy storage device 16, the gear wheel 36 must be moved in a clockwise direction, because the energy storage device 16 now acts in an anticlockwise direction. This movement in a clockwise direction can again be achieved in the three different ways explained above, either solely by rotating the gear wheel 36, by at the same time rotating the gear wheels 32, 36 or by rotating the gear wheel 32 and passively entraining the gear wheel 36 by means of the contact between the pins 46, 50.

[0103] The tensioned state of the energy storage device 16 is illustrated in FIG. 8. Following the introduction of the energy into the energy storage device 16 and activation of the holding device 182, through actuation of the coupling 28 the part 12 can then once again be moved between its two end positions, wherein this movement is symbolised in FIG. 9 through the changed position of the pin 50 in comparison with the position in FIG. 8.

[0104] One of the end positions can thereby be configured such that the pin 50 makes contact with one of the two pins 46, 48, depending on the direction of action of the energy storage device 16.

[0105] Naturally, other energy-storing parts, for example other springs or also hydraulic or pneumatic energy storage devices, can be provided instead of the compression springs.

[0106] The theoretical maximum rotary moveability of the first output shaft 34 relative to the second output shaft 38 can also be described in that if for example the stop surface 90 is in contact with the stop surface 94 of the pin 50, a distance of at least 180° exists between the opposing stop surface 96 of the pin 50 and the stop surface 92. Naturally, as explained, this moveability is the theoretical moveability, if the actuator 10 is not affected by the part 12, that is if the part 12 does not have any stops which limit this maximum rotary moveability.

[0107] Naturally, the pins 46, 48, 50 can also be formed by other projections or can also be provided directly on the output shafts 34, 38. In addition, the gear wheels 32, 36 can also transition integrally into their output shafts.

[0108] The electric motors of the drives 18, 118 can act as generators, both during the movement of the part 12 in normal operation and also with activated energy storage device.

[0109] In normal operation in particular, a control can then be used to adjust the return time taken for the movement of the part 12.