Actuator and method for zeroing a display element

Abstract

Actuator (1) with a display element (4) movably mounted on the outside of a housing (3), wherein the display element (4) is coupled to an output shaft (5) arranged at least partially inside the housing (3) for displaying an actuating position, and wherein the output shaft is connectable to or connected to a valve, wherein the display element (4) is coupled to a coupling element (6) arranged on the outside of the housing (3) for transmitting a movement of the coupling element (6) to the display element (4), the output shaft (5) is coupled to a feedback element (7) arranged inside the housing (3) for transmitting a movement of the output shaft (5) to the feedback element (7), the feedback element (7) is mechanically and / or electrically coupled to the output shaft (5) so that the feedback element (7) performs a corresponding movement to a movement of the output shaft (5),and the coupling element (6) is magnetically coupled to the negative feedback element (7) to transmit a movement of the negative feedback element (7) to the coupling element (6).

Description

[0001] The invention relates to an actuator with a display element movably mounted on the outside of a housing, wherein the display element is coupled to an output shaft arranged at least partially on the inside of the housing to display a setting position.

[0002] Such actuators are known, with the coupling being established by a mechanical connection, possibly via a reduction gear, to the output shaft. The output shaft can be connected or is connected to an actuating element, such as a valve. The mechanical coupling—for example, via a shaft—requires that the housing be penetrated in order to move the display element mounted on the outside for reading.

[0003] Alternatively, it is known to arrange the indicator element behind a sight glass inserted into the housing. In this case, the sight glass must be sealed to seal off the interior of the housing from the outside.

[0004] The invention further relates to a method for zeroing a display element, wherein the display element is movably mounted. Zeroing is necessary, for example, when the initial position of the display element is unknown and the display element is to be moved to a defined zero position.

[0005] From DE 195 37 666 A1 a pointer instrument is known, with a front plate designed as a liquid cell, which has one or more scales and displays.

[0006] From GB 2 010 596 A, magnetic couplings in gas meters are known, wherein a gas meter housing made of magnetic material has a magnetic coupling for transmitting a drive of working parts to an index mechanism outside the housing.

[0007] From US 2010 / 0 064 961 A1 a display device is known in which a pointer is secured to a pointer driving means by the attractive force of magnets, whereby it is possible to avoid overshooting or pulsation of the pointer by sufficient attractive force.

[0008] From DE 42 00 551 A1 a synchronization method for a display device with an electrically controlled stepper motor is known, wherein for the synchronization of the counter of an electronic control device with the zero position of a pointer, defined by a mechanical stop, in a display device which is driven via a reduction gear by a stepper motor with two mutually perpendicular windings and a two-pole rotor, wherein the two windings are alternately connected to a voltage source and a measuring mechanism for determining the voltage induced in the non-energized winding and wherein the pointer is moved step by step up to the mechanical stop and the counter is set to zero if there is no induction, a method is proposed which is considerably less complex than a known method of this type.

[0009] The invention is based on the object of improving the performance characteristics of an actuator.

[0010] To achieve the stated object, the features of claim 1 are provided according to the invention. In particular, to achieve the object, in an actuator of the type mentioned at the outset, the invention proposes that the display element is coupled to a coupling element arranged on the outside of the housing for transmitting a movement of the coupling element to the display element, that the output shaft is coupled to a counter-coupling element arranged on the inside of the housing for transmitting a movement of the output shaft to the counter-coupling element, and that the coupling element is magnetically coupled to the counter-coupling element for transmitting a movement of the counter-coupling element to the coupling element. Due to the magnetic coupling between the external coupling element and the internal counter-coupling element, openings in the housing for transmitting the movement are no longer necessary. This results in improved sealing by the housing.This is particularly advantageous, for example, if the actuator is to be designed to be explosion-proof. This improves the performance characteristics with regard to the sealing provided by the housing.

[0011] In one embodiment of the invention, the coupling element and the counter-coupling element can be arranged at positions opposite one another with respect to a housing wall of the housing. This has the advantage that the magnetic coupling only needs to be transmitted over a short distance. This allows for strong couplings to be established. It is particularly advantageous if the housing wall or even the entire housing is made of a magnetically inactive or non-magnetic material, for example, aluminum, magnesium, a non-magnetic metallic compound, or plastic. This prevents interference with the magnetic coupling by the housing.

[0012] In one embodiment of the invention, the display element can be arranged rotatably. Thus, the setting position of the output shaft can be intuitively displayed as the angular position of the display element.

[0013] In one embodiment of the invention, it can be provided that the coupling element is arranged so that it can be rotated. This allows simple coupling to a rotatable display element. In addition, the space required for moving the coupling element is therefore minimal. Alternatively or additionally, it can be provided that the counter-coupling element is arranged so that it can be rotated. This allows minimal space required for moving the counter-coupling element. It is particularly advantageous if both the coupling element and the counter-coupling element are arranged so that they can be rotated, since movement can then be transmitted particularly easily. In this case, an axis of rotation of the coupling element can be aligned coaxially to an axis of rotation of the counter-coupling element. This allows movements over large angular ranges to be transmitted easily.

[0014] In one embodiment of the invention, the coupling element can be mechanically coupled to the display element. This allows for a simple design on the outside of the housing. An additional power supply for operating the coupling is unnecessary. It is particularly advantageous if the coupling element is rigidly connected to the display element, for example, integrally connected to the display element or formed on it. This allows for a particularly compact and robust design.

[0015] In one embodiment of the invention, the counter-coupling element can be mechanically coupled to the output shaft. This has the advantage that no additional power supply is required to operate the coupling. A further advantage is that a robust, failure-resistant design can be achieved. Alternatively or additionally, the counter-coupling element can be electrically coupled to the output shaft. This has the advantage that the coupling between the output shaft and the counter-coupling element can be configured flexibly. Restrictions on the placement of the counter-coupling element can thus be eliminated.

[0016] In one embodiment of the invention, it can be provided that the counter-coupling element is movable with an electric motor. This is advantageous in that an electrical coupling between the output shaft and the counter-coupling element is easy to implement, for example via electronic transmission of an output signal from a position sensor on the output shaft to the electric motor. The electric motor can be designed as a stepper motor. This is advantageous in that the stepper motor can hold its set position even when de-energized. It is particularly advantageous if the counter-coupling element is movable with the electric motor in operative connection with a position sensor on the output shaft. This provides a simple way of carrying the counter-coupling element along with the output shaft.

[0017] In one embodiment of the invention, it can be provided that the electric motor has a maximum torque that can be applied to the counter-coupling element, which is lower than the torque that can be transmitted between the counter-coupling element and the coupling element. This ensures that the electric motor stops if, for example, the display element becomes blocked. This blockage can be detected on the electric motor, for example, by monitoring the motor current.

[0018] In one embodiment of the invention, it can be provided that the display element with the coupling element is arranged under an at least partially transparent cover. This is advantageous because the display element is arranged in a protected manner. It is also advantageous that parts of the display element that should not be visible at all times or in all positions can be covered.

[0019] In one embodiment of the invention, it can be provided that the coupling element is arranged in a recess of the housing. This is advantageous in that the coupling element can be arranged in a protected manner and with minimal space protruding beyond the housing. Preferably, the coupling element is arranged with the display element in the recess. This prevents the display element from projecting beyond or protruding from the housing. A structurally simple embodiment can provide for the receptacle to be cup-shaped. A cup-shaped recess can be characterized, for example, by having a base and a wall surrounding and delimiting this base.

[0020] In one embodiment of the invention, it can be provided that the coupling element has a permanent magnet. This is advantageous in that a permanent magnetic coupling can be provided which does not require a power supply during operation. Alternatively or additionally, it can be provided that the counter-coupling element has a permanent magnet. Here, too, an energy-saving, permanent magnetic coupling can be provided. A particularly strong coupling can be achieved if both the coupling element and the counter-coupling element each have at least one permanent magnet. This means that the position of the display element can be maintained even if the power supply to the actuator fails. It is particularly advantageous if the permanent magnet or permanent magnets are designed as diametrical magnets. This makes it possible to avoid ambiguities in the alignment of the coupling element relative to the counter-coupling element.A diametrical magnet can, for example, be characterized as a disk-shaped magnet whose magnetization runs parallel to a diameter of the disk. A favorable embodiment can provide that a rotational axis of the coupling element and / or the counter-coupling element runs through the respective permanent magnet and / or that a magnetization of the respective permanent magnet is oriented perpendicular to a rotational axis of the coupling element and / or the counter-coupling element.

[0021] In one embodiment of the invention, it can be provided that a receptacle is formed on the coupling element, in which a correspondingly shaped permanent magnet is arranged. The receptacle thus mimics an outer contour of the permanent magnet. This allows the permanent magnet to be easily inserted into the coupling element with the correct orientation and / or alignment. Alternatively or additionally, it can be provided that a receptacle is formed on the counter-coupling element, in which a correspondingly shaped permanent magnet is arranged. This allows a defined orientation of the inserted permanent magnet with respect to a position of the output shaft to be easily specified and / or adjusted.

[0022] In one embodiment of the invention, the coupling element can be supported by a support element resting on the housing at a point. This is advantageous because the coupling element can be moved with minimal friction losses. The support element can be provided, for example, by a needle-shaped tip and / or a ball.

[0023] In one embodiment of the invention, a limiting means can be formed on the housing, which limits the mobility of the display element. Advantageously, a zero position of the display element can be defined.

[0024] To achieve the stated object, the invention provides the features of the independent method claim in the method. In particular, to achieve the stated object, the invention proposes, in a method of the type described above, that the display element be moved against a limiting means by a magnetically coupled electric motor, and that a position of the display element upon reaching the limiting means, for example a stop, be used as the zero position. Thus, an undefined and / or unknown orientation of the display element can be automatically eliminated. The method can, for example, be executed automatically each time the device to which the display element belongs is switched on.

[0025] It is particularly advantageous if the actuator in the method is designed according to the invention, in particular as described above and / or according to one of the claims directed to an actuator.

[0026] In one embodiment of the invention, it can be provided that reaching the limiting means is detected. It is advantageous in this case that the zeroing can be monitored. In this case, it is advantageous if reaching the limiting means occurs by measuring an operating parameter of the electric motor. This represents a simple way of detecting when the limiting means has been reached by the display element. Preferably, a motor current is measured. The motor current is an easily processed operating parameter that can, for example, provide direct information about the currently developed torque. Since the torque increases when the display element is blocked, reaching the limiting means is particularly easy to process.

[0027] In one embodiment of the invention, it can be provided that when the display element moves against the limiting means on the electric motor, a maximum developable torque is provided that is smaller than the torque required to overcome the preferably magnetic coupling. Thus, the electric motor stops if the coupling element and / or the display element is blocked. This facilitates the assignment of a position of the counter-coupling element to the zero position. Automated zeroing is thus possible by moving the electric motor toward the limiting means until a stop of the electric motor must have occurred and / or is detectable.

[0028] The invention will now be described in more detail using exemplary embodiments, but is not limited to these exemplary embodiments. Further exemplary embodiments result from combinations of the features of one or more claims with one another and / or with one or more features of the exemplary embodiments.

[0029] It shows, in a representation that is partly greatly simplified to explain the invention: Fig. 1 an actuator according to the invention as a block diagram, Fig. 2 a section of the actuator according to Fig. 1 with a display element, a coupling element and a counter-coupling element in sectional view and Fig. 3 four variants of a coupling element or a counter-coupling element in an actuator according to the invention according to Fig. 1.

[0030] Fig. Figure 1 shows an actuator according to the invention, designated overall by 1. The actuator comprises, in a conventional manner, an actuator motor 2 and a gear (not shown) driven by the motor, both of which are arranged in a housing 3.

[0031] A display element 4, which is attached to the outside of the housing 3, can be used to display the setting position of an output shaft 5 to a user outside the housing 3. For this purpose, an operative connection or coupling, described in more detail below, is established between the output shaft 5 and the display element 4, through which the display element 4 is moved with a display symbol 13 corresponding to a movement of the output shaft 5. The output shaft 5 is adjustable via the aforementioned gear with the actuator motor 2.

[0032] The output shaft 5 is driven by the actuator motor 2 in a manner known per se.

[0033] Fig. 2 shows a detailed view of the Fig. 1 only schematically depicts the actuator 1 according to the invention. Shown is a sectional view which, among other things, shows the disc-shaped display element 4 in more detail.

[0034] A coupling element 6 is formed integrally on the display element 4 on a side facing away from the viewer. This mechanically rigidly couples the coupling element 6 to the display element 4, so that the display element 4 and the coupling element 6 are jointly movably mounted on the outside of the housing 3.

[0035] A counter-coupling element 7 is formed on the inside of the housing 3, which is coupled to the output shaft 5 in a manner to be described in more detail. The coupling between the output shaft 5 and the counter-coupling element 7 ensures that a movement of the output shaft 5 is translated into a corresponding movement of the counter-coupling element 7.

[0036] In a manner to be described in more detail, the coupling element 6 and the counter-coupling element 7 are magnetically coupled to one another in such a way that a movement of the counter-coupling element 7 is transmitted and converted into a corresponding movement of the coupling element 6.

[0037] A housing wall 8 is formed between the coupling element 6 and the counter-coupling element 7. The coupling element 6 and the counter-coupling element 7 are arranged at opposite positions with respect to this housing wall 8.

[0038] The display element 4, the coupling element 6 and the counter-coupling element 7 are arranged and mounted so as to be rotatable about a common axis of rotation 9.

[0039] In Fig. 1 shows a position sensor 10 with which a movement and / or setting position of the output shaft 5 can be electrically detected.

[0040] In Fig. 2 shows an electric motor 11 which is electrically coupled to the position sensor 10 in a manner known per se such that the electric motor 11 executes a movement corresponding to a movement of the output shaft 5.

[0041] The electric motor 11 drives the counter-coupling element 7 mechanically.

[0042] In further embodiments, an additional gear can be formed between the electric motor 11 and the counter-coupling element 7. In further embodiments, the counter-coupling element 7 can be mechanically coupled to the output shaft 5 directly or via a gear, so that the counter-coupling element 7 executes a movement corresponding to a movement of the output shaft 5.

[0043] The chain of couplings between the drive shaft 5, the counter-coupling element 7, the coupling element 6 and the display element 4 form the already mentioned active connection for transmitting a movement on the output shaft 5 to the display element 4.

[0044] The display element 4 is arranged on the outside of the housing 3 under a cover 12. The cover 12 is at least partially transparent in order to display the display symbol 13 (cf. Fig. 1) to be made visible at least in a display position applicable to a current setting position of the output shaft 5.

[0045] The cover 12 also serves to support the display element 4.

[0046] A recess 14 is formed on the housing 3, which is open to the outside.

[0047] The already mentioned housing wall 8 forms a bottom of this pot-shaped recess 14.

[0048] The recess 14 has in the embodiment according to Fig. 2 has a two-stage opening, so that an upper part 15 also accommodates the display element 4. This results in a stepped wall which delimits and surrounds the aforementioned bottom of the recess 14.

[0049] The cover 12 is also inserted into the upper part 15.

[0050] To establish the magnetic coupling between the coupling element 6 and the counter-coupling element 7, the coupling element 6 and the counter-coupling element 7 each have at least one permanent magnet 16, 17.

[0051] Fig. Figure 3 shows examples of different types of permanent magnets 16, 17 arranged on the coupling elements 6 and 7, respectively. The types of permanent magnets 16, 17 shown on the coupling element 6 can be combined with any type of permanent magnet on the counter-coupling element 7 to effect the magnetic coupling according to the invention.

[0052] Fig. 3 shows a top view of the coupling element 6 or the identical counter-coupling element 7.

[0053] The axis of rotation of the coupling element 6 or the counter-coupling element 7 is therefore in Fig. 3 arranged perpendicular to the drawing plane.

[0054] Top left shows Fig. 3 the use of a bar magnet with a cuboid outer contour.

[0055] Bottom left shows Fig. 3 the use of a bar magnet with an oval outer contour.

[0056] Bottom right shows Fig. 3 the use of two separate permanent magnets 16, 17. These are each designed as bar magnets, with the dipole moment parallel to the axis of rotation, i.e. perpendicular to the plane of the drawing.

[0057] At the top right, a diametrical magnet is shown as a permanent magnet 16, 17, which has a round outer contour, with the north and south poles each forming a semicircle. The magnetization runs parallel to the diameter of the disc-shaped permanent magnet.

[0058] The arrangement of two unlike poles diametrically opposite each other with respect to a center of rotation or a rotation axis 9 in the coupling element 6 and the counter-coupling element 7 has the advantage that the orientation of the coupling element 6 to the counter-coupling element 7 is clearly determined.

[0059] The use of permanent magnets 16, 17, in which the rotation axis 9 passes through the material of the permanent magnet 16, 17, as shown in Fig.3 in the figures top right, top left and bottom left is the case, has the advantage that the repulsion and attraction forces between the permanent magnet 16 and the permanent magnet 17 in every position of the coupling element 6 relative to the counter-coupling element 7 are sufficiently large to transfer the relative position into a clearly determined relative orientation of the coupling element 6 to the counter-coupling element 7.

[0060] The permanent magnets 16 and 17 are each inserted into a receptacle 18, which is designed to correspond to the respective permanent magnet 16, 17. The permanent magnets 16 and 17 can therefore only be inserted into the coupling element 6 or the counter-coupling element 7 in a precisely defined orientation. Additionally, projections and / or recesses (not shown) can be formed on the permanent magnets 16, 17 to prevent inadvertent interchange of the north and south poles when inserted into the receptacle 18.

[0061] For this purpose, the receptacles 18 are designed correspondingly, in that the receptacles 18 each simulate the contour of a permanent magnet 16, 17 to be inserted. This allows the permanent magnets 16 and 17 to be inserted in only one orientation.

[0062] A support element 19 is formed between the coupling element 6 and the housing wall 8 of the housing, via which the display element 4 with the coupling element 6 is supported on the housing 3.

[0063] The support element 19 is designed as a ball and therefore rests on the housing 3 in a point-like manner.

[0064] In a further embodiment, this point-like contact is achieved in a different way, for example by the support element 19 being designed as a needle or as a pointed projection.

[0065] Furthermore, a limiting means 20 is formed on the housing 3, which limits the rotational movement of the display element 4 at least in one direction.

[0066] This limiting means 20 thus forms a stop for the disc-shaped display element 4. This provides a zero position for the display element 4.

[0067] Due to manufacturing tolerances and other influences, it may happen that a correspondence between a setting position of the counter-feedback element 7 and the display element 4, when the latter is in the zero position, is not known.

[0068] In order to determine this correspondence, the following method according to the invention can be used to zero the display element 4.

[0069] First, the display element 4 is moved against the limiting means 20 by the electric motor 11, which is magnetically coupled via the coupling element 6 and the counter-coupling element 7. As soon as the display element 4 hits the limiting means 20, the display element 4 cannot be moved any further.

[0070] This means that the coupling element 6 can no longer be moved.

[0071] The maximum torque that can be developed by the electric motor 11 is dimensioned such that the magnetic coupling between the coupling element 6 and the counter-coupling element 7 cannot be overcome. Thus, the counter-coupling element 7 also remains stationary if the coupling element 6 is blocked.

[0072] This leads to an increase in the motor current in the electric motor 11, which is recorded as an operating parameter to detect when the limiting device is reached. Any parameter that characterizes a momentarily developed torque, such as the motor current, can be used as the operating parameter. The resulting position of the electric motor 11 is then used and stored as the zero position of the display element 4.

[0073] Alternatively, it can be provided that the electric motor 11 is moved over a certain period of time, for example a period of time required to complete a full revolution.

[0074] Since the torque that can be developed at the electric motor 11 is insufficient to overcome the coupling between the coupling element 6 and the counter-coupling element 7, the electric motor 11 actually stops when the display element 4 reaches the limiting means 20. After the aforementioned period of time has elapsed, the current position of the electric motor 11 is therefore equal to the zero position of the display element 4.

[0075] Normal operation can then be continued with this position.

[0076] In the actuator 1, it is proposed to couple a display element 4 mounted on the outside of a housing 3 to an output shaft 5 of the actuator 1 for displaying a current actuating position, wherein a coupling path comprises a magnetic coupling through a housing wall 8. List of reference symbols 1 actuator 2 actuator motor 3 housings 4 Display element 5 Output shaft 6 coupling element 7 Counter-coupling element 8 Housing wall 9 axis of rotation 10 Position sensor 11 Electric motor 12 Cover 13 Display symbol 14 Recess 15 upper part 16 permanent magnet 17 Permanent magnet 18 recording 19 Support element 20 limiting devices

Claims

[1] Actuator (1) with a display element (4) movably mounted on the outside of a housing (3), wherein the display element (4) is coupled to an output shaft (5) arranged at least partially on the inside of the housing (3) for displaying a setting position, and wherein the output shaft is connectable or connected to a valve, wherein the display element (4) is coupled to a coupling element (6) arranged on the outside of the housing (3) for transmitting a movement of the coupling element (6) to the display element (4), the output shaft (5) is coupled to a counter-coupling element (7) arranged on the inside of the housing (3) for transmitting a movement of the output shaft (5) to the counter-coupling element (7), the counter-coupling element (7) is mechanically and / or electrically coupled to the output shaft (5) so that the counter-coupling element (7) executes a movement corresponding to a movement of the output shaft (5),and the coupling element (6) is magnetically coupled to the counter-coupling element (7) for transmitting a movement of the counter-coupling element (7) to the coupling element (6). [2] Actuator (1) according to claim 1, characterized by that the coupling element (6) and the counter-coupling element (7) are arranged at positions opposite one another with respect to a housing wall (8) of the housing (3). [3] Actuator (1) according to claim 1 or 2, characterized by that the display element (4) is rotatably mounted and / or that the coupling element (6) and / or the counter-coupling element (7) is / are rotatably mounted. [4] Actuator (1) according to one of claims 1 to 3, characterized by that the coupling element (6) is mechanically coupled, in particular rigidly connected, to the display element (4). [5] Actuator (1) according to one of claims 1 to 4, characterized bythat the counter-coupling element (7) is movable with an electric motor (11), in particular a stepper motor, in particular in operative connection with a position sensor (10) on the output shaft (5). [6] Actuator (1) according to one of claims 1 to 5, characterized by that the electric motor (11) has a maximum torque that can be applied to the counter-coupling element (7) which is lower than a torque that can be transmitted between the counter-coupling element (7) and the coupling element (6). [7] Actuator (1) according to one of claims 1 to 6, characterized by that the display element (4) with the coupling element (6) is arranged under an at least partially transparent cover (12) and / or that the coupling element (6) is preferably arranged with the display element (4) in a cup-shaped recess (14) of the housing (3). [8] Actuator (1) according to one of claims 1 to 7, characterized bythat the coupling element (6) and / or the counter-coupling element (7) each have a permanent magnet (16, 17), in particular a diametrical magnet. [9] Actuator (1) according to one of claims 1 to 8, characterized by that a receptacle (18) is formed on the coupling element (6) and / or on the counter-coupling element (7), in each of which a correspondingly shaped permanent magnet (16, 17) is arranged. [10] Actuator (1) according to one of claims 1 to 9, characterized by that the coupling element (6) is supported by a support element (19) resting at a point on the housing (3). [11] Actuator (1) according to one of claims 1 to 10, characterized by that a limiting means (20) is formed on the housing (3) which limits a mobility of the display element (4). [12] Method for zeroing a display element (4), in particular in an actuator (1) according to one of the preceding claims, wherein the display element (4) is movably mounted, wherein the display element (4) is moved against a limiting means (20) by means of a magnetically coupled electric motor (11), reaching the limiting means (20) is detected by measuring a motor current of the electric motor (11), and a position of the display element (4) upon reaching the limiting means (20) is used as the zero position. [13] Method according to claim 12, characterized by that when the display element (4) moves against the limiting means (20) on the electric motor (11), a maximum developable torque is provided which is smaller than a torque required to overcome the magnetic coupling.

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