actuator device

Abstract

Actuator device comprising a fluid-operated contraction unit (2) comprising two first and second head pieces (5, 6) spaced apart from each other in the axial direction of a longitudinal axis (4) and a contraction hose (7) extending between the two head pieces (5, 6) and fluid-tightly attached to both head pieces (5, 6), wherein the contraction hose (7) has the property of undergoing length contraction under radial expansion when pressurized internally, and wherein the contraction hose (7) together with the head pieces (5, 6) defines a drive interior (8) which can be pressurized with a fluidic pressure medium through a drive channel (12) in order to change the mutual distance of the two head pieces (5, 6) within a working stroke range, and comprising a position detection device (3) for detecting at least one axial relative position of the two head pieces (5, 6),the position sensing device (3) has a position sensor (25) arranged outside the contraction unit (2) and connected to the first head piece (5), which is configured to output at least one electrical sensor signal, wherein the position sensing device (3) further has an activation unit (26) attached to the second head piece (6) with an activation rod (28) projecting towards the first head piece (5), characterized in that the position sensing device (3) has a sensor holder (24) attached externally to the first head piece (5) of the contraction unit (2), to which the magnetic field-sensitive position sensor (25) is attached, which extends outside the contraction unit (2) along a length section of the contraction unit (2),wherein the activation rod (28) has a permanent magnetic activation magnet (27) which generates at least one electrical sensor signal from the position sensor (25) and wherein the sensor holder (24) has a fastening groove (44) extending in the longitudinal direction of the contraction unit (2) in which the position sensor (25) is detachably fastened in an axially adjustable manner.

Description

[0001] The invention relates to an actuator device having a fluid-operated contraction unit which has two first and second head pieces spaced apart from one another in the axial direction of a longitudinal axis, and a contraction hose extending between the two head pieces and fastened to both head pieces in a fluid-tight manner, wherein the contraction hose has the property of carrying out a length contraction with radial expansion when subjected to internal pressure, and wherein the contraction hose, together with the head pieces, delimits a drive interior space which can be pressurised with a fluidic pressure medium through a drive channel in order to change the mutual distance between the two head pieces within a working stroke range, and having a position detection device for detecting at least one axial relative position of the two head pieces.

[0002] An actuator device of this type, known from DE 103 37 599 A1, comprises a contraction unit with a contraction tube extending between two head pieces. If a drive interior defined by the contraction tube and the two head pieces is subjected to a fluidic pressure medium, the contraction tube expands and pulls the two head pieces toward each other, reducing the distance between them. Located within the drive interior are two relatively movable components of a position detection device that engage with each other in a telescopically displaceable manner. If a change in the distance between the two head pieces is caused by the application of fluid to the drive interior, this leads to a simultaneous relative movement between the two components of the position detection device, which makes it possible to continuously measure the distance between the two head pieces.The position detection device is designed, for example, as a magnetostrictive displacement measuring device or as a resistance displacement measuring device.

[0003] DE 10 2009 058 653 A1 discloses a fluidically operated compensation unit comprising two coupling plates between which two interlocking telescopic members extend. The two coupling plates are pivotable relative to each other, and a resulting linear relative movement of the telescopic members can be detected by a sensor device to determine the spatial position of the two coupling plates relative to each other.

[0004] DE 10 2009 018 169 A1 discloses an actuating device comprising a flexurally elastic contraction element extending between two spaced-apart end pieces, the interior of which can be pressurized with a fluidic pressure medium to cause a change in the length of the contraction element. Located in an interior space defined by the contraction element is a rotatable drum element around which a cable is wound. This causes the drum element to rotate when the length of the contraction element changes. A sensor is capable of detecting the rotation of the drum element. This allows conclusions to be drawn about the change in the length of the contraction element.

[0005] DE 101 15 864 C1 discloses a fluid-operated vise comprising a clamping element actuated by a fluid-operated contraction device. The operating state of the clamping element can be detected by a sensor that responds to a permanent magnet whose position changes upon actuation of the clamping element.

[0006] From WO 00 / 61952 A1, a contraction unit marketed by the applicant under the name “Fluidic Muscle” is known, which has a flexible contraction tube extending between two head pieces, which is composed of a rubber-elastic tube body and a flexible and at the same time tensile-resistant strand structure integrated into this tube body.

[0007] US 505 2273 A discloses a pneumatic actuator comprising a tubular body made of a rubber-like elastic material and a braided structure of organic or inorganic high-strength fibers reinforcing an outer surface of the tubular body. Closure elements tightly seal the ends of the tubular body, with at least one of the closure elements having a fluid port. The tubular body deforms to increase its diameter when a pressurized fluid is introduced through the connecting passage to generate a contraction force in the longitudinal direction. Strain gauges that detect the contraction provide signals at a closure element that correspond to the contraction force of the actuator.

[0008] The invention is based on the object of creating an actuator device equipped with a fluid-operated contraction unit in which the relative position between the two head pieces can be monitored simply and cost-effectively.

[0009] To achieve this object, in conjunction with the features mentioned at the outset, it is provided that the position detection device has a sensor holder attached externally to the first head piece of the contraction unit, to which a magnetic field-sensitive position sensor is attached, which is designed to output at least one electrical sensor signal and extends outside the contraction unit along a length section of the contraction unit, and that the position detection device has an activation unit attached to the second head piece with an activation rod projecting in the direction of the first head piece, wherein the activation rod has a permanent magnetic activation magnet which produces the at least one electrical sensor signal of the position sensor.

[0010] The actuator device according to the invention has a fluid-operated contraction unit with two head pieces and a contraction tube extending between the two head pieces. Together, these aforementioned components define a drive interior, which can be pressurized with a fluidic pressure medium in order to change the mutual distance between the two head pieces within a working stroke range. The change in distance is based on the fact that the radial expansion of the contraction tube, which can be caused by the internal pressurization of the drive interior, is accompanied by a longitudinal contraction of the contraction tube, which draws the two head pieces axially toward each other. Relieving pressure in the drive interior allows the head pieces to increase their mutual distance again. The contraction tube is constructed in particular according to the content of WO 00 / 61952 A1.The additional position detection device allows the detection of at least one axial relative position of the two head pieces. This enables operational monitoring of the contraction unit. For example, the sensor signal from the position sensor can be used to set and / or determine a tensile force that is transmitted via the two head pieces to external structures attached to them. Preferably, any axial relative position within the working stroke range can be detected. The position detection device includes, on the one hand, a sensor holder fixed to the outside of the first head piece, to which a magnetic field-sensitive position sensor is attached, and, on the other hand, an activation unit attached to the second head piece, which has an activation rod projecting towards the first head piece and equipped with a permanent magnetic activation magnet.During a linear relative movement between the two head pieces, the axial relative position between the activation magnet of the activation rod and the magnetic field-sensitive position sensor changes simultaneously, causing the position sensor to output a sensor signal corresponding to at least one axial relative position of the two head pieces. Since the position sensor is located on the outside of the contraction unit, it is easy to install and, if necessary, adjust. Any illuminated indicators arranged on the position sensor are clearly visible, and any input devices present on the position sensor, for example, enabling parameterization, are easily accessible. With appropriate design, a conventional contraction unit can be retrofitted with the position detection device relatively easily.

[0011] Advantageous further developments of the invention emerge from the subclaims.

[0012] Preferably, the activation magnet is held by the activation rod in such a position relative to the position sensor that it is capable of activating the position sensor at any relative position of the two head pieces within the working stroke range, i.e., generating a sensor signal. Thus, any axial relative position of the two head pieces within the working stroke range can be detected by the position detection device and used for subsequent evaluations.

[0013] Preferably, the position detection device is designed to continuously detect all axial relative positions of the two head pieces within the working stroke range. The position sensor preferably has an analog output, at which a path-proportional electrical sensor signal is provided within the detection range, which corresponds at least to the working stroke range of the two head pieces. Additionally or alternatively, the position sensor can also be designed for digital signal output. It is also possible to design the position sensor so that the sensor signals are digitally coded analog values.

[0014] In principle, the position detection device can alternatively be designed to detect only one or more predetermined axial relative positions of the two head pieces. In this way, for example, an unactuated and an actuated state of the contraction unit can be detected without contact. In each of these two operating states, the position sensor outputs a corresponding sensor signal.

[0015] Preferably, the arrangement is such that the position sensor and the activation rod axially overlap in every axial relative position of the two head pieces. The activation magnet is expediently arranged on the activation rod such that it occupies a position that overlaps with the position sensor, i.e., is arranged alongside the position sensor, in every axial relative position of the two head pieces.

[0016] In one possible embodiment, the activation rod is formed in one piece and is permanently locally magnetized at the appropriate location to create the activation magnet. A particularly simple and cost-effective solution, which is preferred, however, provides for the activation rod to have a support rod and an activation magnet formed separately from the support rod, the activation magnet being held by the support rod. The support rod has a front end portion facing the first head piece and a rear end portion opposite thereto, and is fixed to the second head piece in the region of its rear end portion. The support rod is expediently made of a non-magnetic, non-magnetizable material, for example aluminum or plastic. The support rod can be formed in one piece or in multiple parts.

[0017] The activation magnet can, for example, be arranged on the front side in the region of the front end section of the support rod. However, a preferred embodiment is one in which the activation magnet is arranged between the two opposing front and rear end sections of the support rod, spaced from both the front end section and the rear end section.

[0018] It is also advantageous if the activation magnet is positioned on the support rod in such a way that it is always at the axial height of the contraction tube, at an axial distance from both headpieces. If the activation rod is located outside the contraction tube, the activation magnet always assumes a position alongside the contraction tube.

[0019] The position sensor is arranged on the sensor holder in such a way that it extends longitudinally alongside the contraction tube along a partial length of the contraction tube. In particular, the position sensor is positioned such that it extends along a length section of the contraction tube that directly adjoins the first headpiece.

[0020] Preferably, the sensor holder is equipped with a holding arm which, starting from the first head piece, extends axially freely towards the second head piece and extends along the contraction tube.

[0021] The position sensor is preferably releasably fixed to the sensor holder. This allows it to be easily replaced if necessary. The position sensor is preferably arranged on the sensor holder in such a way that it can be fixed to the sensor holder in different axial working positions. The sensor holder preferably has a fastening groove extending in the longitudinal direction of the contraction unit, in which the position sensor is releasably fastened in an axially adjustable manner. For example, the position sensor is equipped with a clamping device by means of which it can be releasably clamped to the sensor holder in the fastening groove.

[0022] In principle, the sensor holder could be designed as a single piece with the first headpiece. However, the sensor holder is preferably a separate component from the first headpiece, which is attached to the first headpiece by a fastening device, particularly in a detachable manner. The fastening device allows a contraction unit to be equipped with a position detection device only when needed. The fastening device expediently has a fastening section formed as a component of the sensor holder, which is fixed to the first headpiece by clamping or some other means.

[0023] A particularly advantageous embodiment is one in which the activation rod has a front end section axially facing the first head piece. This front end section is designed as a guide section that extends into a guide recess that is fixed relative to the first head piece in a linearly displaceable and radially supported manner. This effectively ensures that the two head pieces always maintain their coaxial position, even under unfavorable transverse loading, so that the radial distance between the position sensor and the activation magnet with respect to the longitudinal axis of the contraction unit also remains constant, ensuring high position detection accuracy.

[0024] The guide recess can be formed directly in the first head piece or in a guide part that is attached to the first head piece as a separate component.

[0025] The activation unit is arranged either outside or inside the contraction unit. If it is located outside the contraction unit, the activation rod extends alongside and parallel to the contraction tube. In this case, any guide recess for the activation rod is expediently formed in the sensor holder, so that the sensor holder simultaneously forms a guide part into which the activation rod, with a guide section, inserts axially displaceably.

[0026] If the activation unit is located within the contraction unit, the activation rod extends in the drive interior from the second head piece toward the first head piece. In this case, it is advantageous if the activation rod extends axially through the drive interior along its entire length and, with a front end section acting as a guide section, extends into a guide recess in the first head piece, which opens out at an inner end face of the first head piece that defines the drive interior.

[0027] A drive channel of the contraction unit, which serves for the controlled application of fluid to the drive interior, is expediently formed in the first head piece and opens into the drive interior at an axial inner end face of the first head piece. If a linear guide for the activation rod is desired, it is advantageous in this context if the activation rod, with its guide section, extends into the inner end section of the drive channel, and this inner end section of the drive channel is designed as a guide recess.

[0028] The activation unit is expediently designed separately from the second headpiece and is attached to the second headpiece by means of a fastening device, in particular in a detachable manner. The fastening device preferably comprises a fastening section formed as a component of the activation unit, which is clamped to the second headpiece. However, other fastening methods are also possible.

[0029] The contraction tube of the contraction unit expediently contains a tube body made of a rubber-elastic material and a strand structure coaxial with the tube body, which is embedded in the material of the tube body. The strand structure is composed of a plurality of flexibly flexible and simultaneously axially tensile-resistant fiber strands, which are arranged in particular in a crossover configuration. The contraction tube, including the strand structure, is attached to the two head pieces, so that the strand structure is capable of pulling the two head pieces toward each other when the contraction tube expands radially due to the application of internal pressure.

[0030] The invention is explained in more detail below with reference to the accompanying drawings, which show: Fig. 1 a preferred embodiment of the actuator device according to the invention in a perspective view, Fig. 2 a side view of the actuator device from Fig. 1 with view direction according to arrow II from Fig. 1, Fig. 3 a longitudinal section of the actuator device according to section line III-III of Fig. 2, where a wall section of the contraction tube is additionally shown separately in an enlarged format, Fig. 4 shows a further side view of the actuator device, viewed in the direction of arrow IV from Fig. 2, Fig. 5 a longitudinal section of the actuator device according to section line VV Fig. 4, where in addition to an unactuated basic state, an actuated operating state with head pieces brought closer together is illustrated in dotted lines, Fig. 6 a cross-section of the actuator device according to section line VI-VI Fig. 3, Fig. 7 shows a further advantageous embodiment of the actuator device in a perspective view, Fig. 8 a side view of the actuator device from Fig. 7 with view according to arrow VIII from Fig. 7, Fig. 9 a longitudinal section of the actuator device according to section line IX-IX Fig. 8, where a wall section of the contraction tube is additionally shown separately in an enlarged form, Fig. 10 shows a further side view of the actuator device, viewed in the direction of arrow X Fig. 8, Fig. 11 a longitudinal section of the actuator device according to section line XI-XI Fig. 10, where in addition to an unactuated basic state, an actuated operating state with head pieces brought closer together is illustrated in dotted lines, Fig. 12 a longitudinal section of the actuator device according to section line XII-XII Fig. 9.

[0031] Unless otherwise stated in individual cases, the following statements apply to all illustrated embodiments of the actuator device designated as a whole by reference number 1.

[0032] The actuator device 1 contains a contraction unit 2, which can be actuated by a controlled fluid application from a fluidic pressure medium. The fluidic pressure medium is, in particular, compressed air. The actuator device 1 is preferably designed as a pneumatic actuator device 1. Operation with other compressed gases or even with hydraulic fluid is also possible.

[0033] The actuator device 1 further includes a position detection device 3 arranged on the contraction unit 2. By way of example, the contraction unit 2 and the position detection device 3 together form the actuator device 1.

[0034] The contraction unit 2 has a longitudinal extension with a longitudinal axis 4. The contraction unit 2 includes two head pieces 5, 6, which are spaced apart from one another in the axial direction of the longitudinal axis 4, as well as a contraction hose 7, which extends coaxially between the two head pieces 5, 6 and is attached to one of the two head pieces 5, 6 with each of its two opposite axial end sections 9 in a sealed manner. For easier differentiation, the two head pieces 5, 6 are also referred to below as the first head piece 5 and the second head piece 6. Together, the contraction hose 7 and the two head pieces 5, 6 define a drive interior 8 of the contraction unit 2.

[0035] A drive channel 12 opens into the drive interior 8 and passes through one of the two head pieces 5, 6, which is the first head piece 5 by way of example. The first head piece 5 has an inner end face 13 that axially delimits the drive interior 8 and at which one end the drive channel 12 opens. An opposite end of the drive channel 12 forms a connection opening 14 and is located on the outer surface of the first head piece 5. During operation of the actuator device 1, a control valve device is connected to this connection opening 14, by means of which the fluid pressure in the drive interior 8 can be controlled. The control valve device is capable of selectively feeding fluidic pressure medium into the drive interior 8, removing it from the drive interior 8, or locking it in the drive interior 8.In this context, the control valve device is connected to both a pressure source and a pressure sink, the latter in particular to the atmosphere. To actuate the control valve device, which preferably also belongs to the actuator device 1, an electronic control unit is expediently provided, which, like the control valve device, is not further illustrated in the drawing.

[0036] The contraction tube 7 is structured such that it expands radially when internal pressure is applied and simultaneously undergoes a length contraction. When the drive interior 8 is depressurized, the contraction unit 2 assumes the unactuated basic state shown in the drawing, which results from the fact that the contraction tube 7 is not deformed and has a certain initial length. In this basic state, the contraction tube 7 has a hollow cylindrical shape between the two head pieces 5, 6 with a constant diameter along its entire length.

[0037] By feeding the fluid pressure medium into the drive interior 8, an overpressure is built up in the drive interior 8, by means of which the contraction unit 2 is moved into a Fig. 5 and Fig. 11 is moved to the actuated operating state, schematically indicated by dash-dotted lines. In this actuated operating state, the contraction tube 7 is radially expanded and simultaneously axially shortened, so that the two head pieces 5, 6 assume a relative position closer to one another than in the initial state. Subsequent pressure relief of the drive interior 8 causes the two head pieces 5, 6 to move away from each other again until the initial, unactuated state is ultimately restored.

[0038] The axial relative position of the two head pieces 5, 6 can be variably and, in particular, continuously adjusted by correspondingly specifying the internal pressure prevailing in the drive interior 8 within a stroke range determined by the deformability of the contraction tube 7, which is referred to below as the working stroke range. The axial relative movement 15 of the two head pieces 5, 6, which can be caused by the actuation of the contraction unit 2, is illustrated in the drawing by a double arrow.

[0039] Each head piece 5, 6 has a fastening interface 16, which allows the attachment of a respective head piece 5, 6 to one of two in the Fig. 5 and Fig. 11, which are only indicated by dash-dotted lines and are movable relative to one another. If both external structures 17, 18 are movable, the axial relative movement 15 is expressed in a movement of both head pieces 5, 6. If, however, only one of the two external structures 17, 18 is movable, the head piece 5 or 6 attached to it is fixed in position, and the axial relative movement 15 is expressed in a relative movement of the other head piece 6, 5 alone.The embodiments show a stationary fixation of the first head piece 5 to an external structure 17, which belongs, for example, to a machine frame, whereas the second head piece 6 is attached to a movable external structure 18, for example to a machine slide, so that the axial relative movement 15 during operation of the contraction unit 2 is carried out exclusively by the second head piece 6 together with the external structure 18 attached thereto.

[0040] The length contraction that occurs when internal pressure is applied results, for example, from a special structure of the contraction tube 7. The contraction tube 7 has, as can be seen in particular from the enlarged sections of the Fig. 3 and Fig. 9, a hose body 22 consisting of a rubber-elastic material and a strand structure 23 arranged coaxially to the hose body 22 and embedded at least partially and in particular in its entirety in the rubber-elastic material of the hose body 22. The strand structure 23 is fastened at the axial end sections 9 together with the hose body 22 to the two head pieces 5, 6.

[0041] The strand structure 23 expediently consists of a plurality of flexibly flexible yet highly tensile fiber strands 23a arranged in a cross-over configuration, as is evident, for example, from WO 00 / 61952 A1 cited above. Due to the strand structure 23, particularly high tensile forces can be transmitted to the two head pieces 5, 6 and thus to the external structures 17, 18 fixed thereto during the axial expansion of the hose body 22.

[0042] The position detection device 3 enables the detection of at least one axial relative position of the two head pieces 5, 6. Preferably and according to the illustrated embodiments, the position detection device 13 is designed such that it enables continuous detection of all axial relative positions of the two head pieces 5, 6 within the working stroke range.

[0043] The position detection device 3 includes, on the one hand, a sensor holder 24 mounted on the outside of the first head piece 5 and a magnetic field-sensitive position sensor 25 fastened to the sensor holder 24. The position detection device 3 also includes an activation unit 26 mounted on the second head piece 6, which has an activation magnet 27 with permanent magnetic properties. The activation magnet 27 is part of an activation rod 28 of the activation unit 26, which extends from the second head piece 6 toward the first head piece 5 and, in doing so, also toward the position sensor 25 fastened to the first head piece 5 via the sensor holder 24.

[0044] The activation magnet 27 is preferably positioned on the activation rod 28 such that it is constantly within the influence range of the position sensor 25. It can therefore activate the position sensor 25 at any relative position assumed between the two head pieces 5, 6 within the working stroke range, such that the position sensor 25 outputs an electrical sensor signal. The electrical sensor signal corresponds to the current relative position between the two head pieces 5, 6.

[0045] For example, the position sensor 25 is equipped with a Hall sensor device that can be activated by the magnetic field of the activation magnet 27 to output the sensor signal. Alternatively, the position sensor 25 can also be based on a different detection principle, for example, a magnetostrictive measuring principle.

[0046] The generated electrical sensor signal is output, for example, via an electrical cable 32 connected to the position sensor 35 and fed, for example, to the electronic control unit mentioned above. Alternatively or additionally, wireless signal transmission can also be provided.

[0047] The position sensor 25 is designed, for example, such that the sensor signal is an electrical signal proportional to the axial relative position of the two head pieces 5, 6, which has a minimum current value in the unactuated basic state of the contraction unit 2 and has a maximum current value in an actuated operating state in which the two head pieces 5, 6 are pulled as far as possible towards each other.

[0048] It goes without saying that the sensor signal can additionally or alternatively also be output digitally.

[0049] The position sensor 25 expediently has an input device 33, which allows it to be manually parameterized as needed. It is also advantageous if the position sensor 25 is equipped with an illuminated display device 34 capable of visualizing the operating states of the position sensor 25.

[0050] The position sensor 25 extends outside the contraction unit 2 along a length of the contraction unit 2, wherein it is expediently designed and arranged such that it does not axially project beyond the contraction unit 2. The position sensor 25 preferably extends axially along the contraction tube 7, starting from the first head piece 5, at a radial distance from the contraction tube 7. The activation unit 26 is expediently designed such that the position sensor 25 and the activation rod 28 axially overlap in every axial relative position of the two head pieces 5, 6. The activation magnet 27 is, in particular, integrated into the activation rod 28 such that it occupies a position alongside the position sensor 25 in every relative position of the two head pieces 5, 6.

[0051] The sensor holder 24 has a fastening section 35, via which it is fastened to the first headpiece 5. The sensor holder also has a holding arm 36 extending from the fastening section 35 along the side of the contraction unit 2 toward the second headpiece 6, to which the position sensor 25 is fastened.

[0052] The axial length of the holding arm 36 is selected such that it ends next to the contraction tube 7, axially spaced from the second headpiece 6. It therefore has an axially opposite free end at the fastening section 35, which faces the second headpiece. At this free end, the holding arm 36 has a front end face 37.

[0053] Viewed from the side, the sensor holder 24 is preferably L-shaped. Of the two L-shaped legs, one forms the fastening section 35, and the other the holding arm 36.

[0054] The sensor holder 24 is, by way of example, formed separately from the first head piece 5. It is fastened to the first head piece 5 by a fastening device 38 in a preferably detachable manner. By way of example, the fastening section 35 is a component of the fastening device 38 belonging to the sensor holder 24, which is detachably fixed to the first head piece 5. By way of example, the fastening section 35 is designed as a fastening tab having an opening with which it is plugged onto a threaded socket 42 formed axially projecting on the first head piece 5, wherein the fastening section 35 is axially clamped to the first head piece 5 by a fastening nut 43 screwed onto the threaded socket 42. In the exemplary embodiment of the Fig. 7 to 12, the fastening nut 43 is only in the Fig. 9 and Fig. 10 shown.

[0055] In a non-illustrated embodiment, the fastening section 35 is designed as a clamp which at least partially encloses the first head piece 5 radially outwardly and is clamped to the outer circumference of the first head piece 5.

[0056] Conveniently, the threaded connector 42 also forms the fastening interface 16 arranged on the first head piece 5.

[0057] The position sensor 25 is expediently fixed in a fastening groove 44 formed in the holding arm 36 and extending parallel to the longitudinal axis 4. The position sensor 25 expediently includes a clamping device 45 with which it can be releasably clamped in the fastening groove 44.

[0058] It is advantageous if the position sensor 25 is adjustable with respect to the sensor holder 24 for individual adaptation to the dimensions of the contraction unit 2. For example, with the clamping device 45 released, the position sensor 25 can be very easily axially displaced in the fastening groove 44 into the desired working position and releasably fixed there by means of the clamping device 45.

[0059] The fastening groove 44 is expediently formed in the holding arm 36 on the longitudinal side facing away from the contraction unit 2. This facilitates the installation of the position sensor 25 and its adjustment and operational monitoring. The fastening groove 44 preferably has an undercut cross-sectional contour with a neck section and a correspondingly wider anchoring section. The clamping device 45 expediently extends into the anchoring section, so that in the clamped state, it additionally secures the position sensor 25 with a positive fit against being pulled out through the neck section.

[0060] What is common to the illustrated embodiments is that the activation rod 28 of the activation unit 26 is formed in several parts and has a support rod 46 which carries the activation magnet 27 which is formed separately in this regard.

[0061] The activation rod 28 or its support rod 46 has a rear end portion 47 in the region of which it is attached to the second head piece 2. An axially opposite front end portion of the activation rod 28 or support rod 46 faces the first head piece 5.

[0062] The support rod 46 is made of a non-magnetizable, non-magnetic material, so that it has little or no influence on the magnetic field of the activation magnet 27. It is made of aluminum, stainless steel, or plastic, for example.

[0063] The activation magnet 27 is expediently placed on the support rod 46 in such a way that, regardless of the axial relative position of the two head pieces 5, 6, it assumes a position which is at the axial height of the contraction tube 7 at an axial distance from both head pieces 5, 6.

[0064] The activation unit 26 has a fastening section 52, via which it is fastened to the second headpiece 6. Preferably, and according to the exemplary embodiments, the activation unit 26 is designed separately from the second headpiece 6 and is attached to the second headpiece 6 by a fastening device 53. The fastening section 52 of the activation unit 26 represents a component of the fastening device 53.

[0065] In the Fig. In the embodiment of the actuator device 1 illustrated in Figures 1 to 6, the activation unit 26, as well as the position sensor 25 and the sensor holder 24, are arranged outside the contraction unit 2. The activation unit 26 is attached externally to the second head piece 6 via the attachment section 52, with the activation rod 28 extending from the second head piece 6 outside the drive interior 8, alongside the contraction tube 7, toward the first head piece 5.

[0066] The fastening section 52 of this external activation unit 26 is designed, for example, as a fastening tab having an opening through which it is attached to an axially projecting threaded stud 54 of the second head piece 6. The fastening section 52 is axially clamped to the second head piece 6 by means of a fastening nut 55 screwed onto the threaded stud 54.

[0067] The threaded connector 54 expediently also forms the fastening interface 16 formed on the second head piece 6.

[0068] As an alternative to the fastening method described, it is also possible, for example, to design the fastening section 52 of the external activation unit 26 as a clamp which at least partially encloses the second head piece 6 on its radial outer circumference and is releasably clamped to the second head piece 6.

[0069] The externally arranged activation unit 26 of the embodiment according to Fig. 1 to 6, viewed from the side, preferably has an L-shape. Of the two L-shaped legs of the activation unit 26, one forms the activation rod 28 and the other the fastening section 52.

[0070] In the Fig. In the embodiment of the actuator device 1 illustrated in Figures 7 to 12, the activation unit 26 is arranged inside the contraction unit 2, with the activation rod 28 extending axially within the drive interior 8. This can thus be referred to as an internal activation unit 26.

[0071] This internal activation unit 26 has a rear end section 56 facing the second head piece 6, which forms the fastening section 52 used for fixation to the second head piece 6. For example, this fastening section 52 is designed as a fastening stud 52a anchored in a fastening recess 57 of the second head piece 6. The fastening recess 57 extends axially in the second head piece 6 and opens out at the inner end face 58 of the second head piece 6 facing the drive interior 8.

[0072] With the fastening stud 52a, the activation unit 52 is, for example, screwed and / or pressed and / or glued into the fastening recess 57. Together, the fastening section 52, designed as a fastening stud 52a, and the fastening recess 57 form a fastening device 53, via which the internal activation unit 26 is fastened to the second head piece 6.

[0073] Starting from the fastening section 52, the activation rod 28 of the activation unit 26 arranged inside the contraction unit 2 extends axially within the drive interior 8 in the direction of the first head piece 5. The activation rod 28, like the activation rod 28 of the activation unit 26 arranged outside the contraction unit 2, has a front end section 48 facing the first head piece 5, which ends freely without fastening.

[0074] In the illustrated embodiment, the drive interior 8 is penetrated by the activation rod 28 along its entire length, and the activation rod 28 extends axially movable with its front end portion 28 into the first head piece 5. According to a non-illustrated embodiment, the activation rod 28 ends within the drive interior 8 at an axial distance in front of the first head piece 5.

[0075] As from Fig. 9, the activation magnet 27 is also preferably arranged in the activation rod 28 arranged in the drive interior 8 such that it is arranged alongside the position sensor 25, regardless of the axial relative position of the two head pieces 5, 6 with respect to the longitudinal axis 4. In contrast to the embodiment of the Fig. 1 to 6, where the activation magnet 27 is located outside the contraction tube 27 between this and the position sensor 25, it is in the embodiment of the Fig. 7 to 12 arranged within the drive interior 8.

[0076] The activation rod 28 extends within the drive interior 8 preferably coaxially to the central longitudinal axis 4 running along the center of the contraction tube 7. In principle, however, an eccentric arrangement of the activation rod 28 with respect to the longitudinal axis 4 would also be possible.

[0077] The activation unit 26 located in the drive's interior 8 reduces the volume that must be filled and emptied by the fluid pressure medium when the contraction unit 2 is actuated. Only a very small dead space exists. This reduces fluid consumption and improves response.

[0078] The cross-section of the activation rod 28 is, in principle, arbitrary. According to the exemplary embodiments, a cylindrical, and in particular a circular-cylindrical, outer contour is advantageously selected.

[0079] In principle, the activation unit 26 can be designed such that its activation rod 28 has no transverse support with respect to the first head piece 5. However, it is advantageous if such transverse support is present, which does not impede the axial relative movement 15, in order to always ensure a constant distance between the activation magnet 27 and the position sensor 25 at right angles to the longitudinal axis 4, regardless of the axial relative movement 15. This reliably eliminates erroneous sensor signals from the position sensor 25 due to radial distance changes.

[0080] Both illustrated embodiments of the actuator device 1 are equipped with transverse support measures of the type explained above. These are preferably implemented by the front end portion 48 of the activation rod 28 acting as a guide portion 62, which extends into a guide recess 63 fixed relative to the first head piece 5 in a linearly displaceable and radially supported manner.

[0081] The guide recess 63 can be formed in a guide part 64 which is separate from the first head piece 5 and is fastened to the first head piece 5. In the embodiment of the Fig. This is the case in Figures 1 to 6. Here, the sensor holder 24 functions as a guide part 64, in which the guide recess 63 is formed in the sensor holder 24. The guide recess 63 preferably extends in the holding arm 36, specifically parallel to the longitudinal axis 4, wherein it opens at the front end face 37 with an opening 65, and the guide section 62 slides into the guide recess 63 through the opening 65.

[0082] As the example of the Fig. 1 to 6, the activation magnet 27 can be positioned such that it is located inside the guide recess 63 regardless of the relative position of the two head pieces 5, 6.

[0083] In the embodiment of the Fig. 7 to 12, the guide recess 63 is formed directly in the first head piece 5. It extends coaxially to the longitudinal axis 4 and has a mouth opening 66 on the inner end face 13 of the first head piece 5. The activation rod 28, with its guide section 62, slides through the mouth opening 66 into the guide recess 63 of the first head piece 5.

[0084] If the drive channel 12 passes through the first head piece 5, it is advantageous if the inner end section of the drive channel 12, which opens into the drive interior 8 at the inner end face 13, forms the guide recess 63. This eliminates the need for a separate guide recess 63. In the embodiment of the Fig. This is the case with Figures 7 to 12. To ensure that the guide section 62 extending into the drive channel 12 does not impair the supply and discharge of pressure medium with respect to the drive interior 8, it is advantageous if a slightly smaller cross-section is selected for the guide section 62 than for the inner end section of the drive channel 12, which functions as a guide recess 63. This leaves, for example, an annular flow gap 67 between the channel wall of the drive channel 12 and the guide section 62, through which the fluid pressure medium can flow. In this case, the transverse support of the guide section 62 can be subject to slight radial play.

[0085] However, even if an order is made in accordance with Fig. 7 to 12 analogous to the embodiment of the Fig. 1 to 6, a play-free transverse support of the guide section 62 can be achieved if the flow gap 67 is realized in such a way that the guide section 62 partially abuts with its outer circumference on the inner circumference of the guide recess 63 and has at least one longitudinal groove or flattened portion on its outer circumference, which enables fluid flow along the guide section 62. Additionally or alternatively, at least one longitudinal groove or flattened portion can also be formed on the inner circumference of the guide recess 63.

[0086] A separately designed activation magnet 27 can, for example, be Fig. 3 can be fixed to the support rod 46 by providing a receiving recess 68 laterally in the support rod 46, into which the activation magnet 27 is inserted. The activation magnet 27 is fixed here, for example, by locking and / or gluing. For example, the activation magnet 27 is block-shaped according to Figure 3.

[0087] Another mounting option is based on the Fig.9 to 11 in the second embodiment. Here, the support rod 46 is formed in two parts in its longitudinal direction and has a rear rod section 72, into which a front rod section 73 with a small diameter is inserted at the front, for example by screwing, pressing, and / or gluing. The activation magnet 27 is designed here as a ring magnet, which is held axially immovably in an annular groove jointly defined by the two rod sections 72, 73. The front rod section 73 simultaneously forms the guide section 62.

Claims

[1] Actuator device, with a fluid-operated contraction unit (2) which has two first and second head pieces (5, 6) spaced apart from one another in the axial direction of a longitudinal axis (4), and a contraction hose (7) extending between the two head pieces (5, 6) and fastened to both head pieces (5, 6) in a fluid-tight manner, wherein the contraction hose (7) has the property of carrying out a length contraction under radial expansion when subjected to internal pressure, and wherein the contraction hose (7) together with the head pieces (5, 6) delimits a drive interior (8) which can be pressurised with a fluidic pressure medium through a drive channel (12) in order to change the mutual distance between the two head pieces (5, 6) within a working stroke range, and with a position detection device (3) for detecting at least one axial relative position of the two head pieces (5, 6),which has a position sensor (25) arranged outside the contraction unit (2) and connected to the first head piece (5), which is designed to output at least one electrical sensor signal, wherein the position detection device (3) further has an activation unit (26) attached to the second head piece (6) with an activation rod (28) projecting in the direction of the first head piece (5), , characterized byin that the position detection device (3) has a sensor holder (24) which is attached externally to the first head piece (5) of the contraction unit (2), to which sensor holder the magnetic field-sensitive position sensor (25) is fastened, which extends outside the contraction unit (2) along a length section of the contraction unit (2), wherein the activation rod (28) has a permanent magnetic activation magnet (27) which generates the at least one electrical sensor signal of the position sensor (25), and wherein the sensor holder (24) has a fastening groove (44) which extends in the longitudinal direction of the contraction unit (2), in which fastening groove the position sensor (25) is detachably fastened in an axially adjustable manner. [2] Actuator device according to claim 1, characterized bythat the activation magnet (27) is held by the activation rod (28) in such a relative position to the position sensor (25) that it is capable of activating the position sensor (25) at any relative position of the two head pieces (5, 6) lying within the working stroke range for the purpose of generating a sensor signal. [3] Actuator device according to claim 1 or 2, characterized by that the position detection device (3) is designed to continuously detect all axial relative positions of the two head pieces (5, 6) within the working stroke range. [4] Actuator device according to one of claims 1 to 3, characterized by that the position sensor (25) and the activation rod (28) axially overlap in each axial relative position of the two head pieces (5, 6). [5] Actuator device according to one of claims 1 to 4, characterized byin that the activation rod (28) has a support rod (46) which carries the activation magnet (27) which is designed separately from the support rod (46) and which has a front end section (48) facing the first head piece (5) and a rear end section (47) opposite thereto, wherein it is fastened to the second head piece (6) in the region of its rear end section (47). [6] Actuator device according to claim 5, characterized by that the support rod (46) consists of a non-magnetic, non-magnetizable material, expediently of aluminum or plastic. [7] Actuator device according to claim 5 or 6, characterized by that the activation magnet (27) is arranged on the support rod (46) in such a way that, regardless of the axial relative position of the two head pieces (5, 6), it assumes a position which lies at the axial height of the contraction tube (7) at an axial distance from both head pieces (5, 6). [8] Actuator device according to one of claims 1 to 7, characterized by that the position sensor (25) attached to the sensor holder (24) extends along a partial length of the contraction tube (7) alongside the contraction tube (7). [9] Actuator device according to one of claims 1 to 8, characterized by that the sensor holder (24) fastened to the first head piece (5) of the contraction unit (2) has a holding arm (36) which, starting from the first head piece (5), ends freely and extends a short distance in the direction of the second head piece (6) and thereby extends longitudinally next to the contraction tube (7), to which holding arm the position sensor (25) is fastened. [10] Actuator device according to one of claims 1 to 9, characterized bythat the sensor holder (24) is designed separately from the first head piece (5) and is fastened to the first head piece (5) by a fastening device (38), wherein the fastening device (38) expediently has a fastening section (35) designed as a component of the sensor holder (24) and fixed to the first head piece (5). [11] Actuator device according to one of claims 1 to 10, characterized by in that the activation rod (28) has a front end section (48) axially facing the first head piece (5), said front end section (48) being designed as a guide section (62) which, in a linearly displaceable and radially supported manner, extends into a guide recess (63) which is stationary with respect to the first head piece (5). [12] Actuator device according to claim 11, characterized bythat the guide recess (63) is formed directly in the first head piece (5) or is formed in a guide part (64) which is fastened to the first head piece (5) as a separate component. [13] Actuator device according to one of claims 1 to 12, characterized by that the activation unit (26) is arranged outside the contraction unit (2), wherein the activation rod (28) extends longitudinally next to the contraction tube (7). [14] Actuator device according to claim 13 in conjunction with claim 12, characterized by that the sensor holder (24) has the guide recess (63) and at the same time forms the guide part (64). [15] Actuator device according to one of claims 1 to 14, characterized by that the activation unit (26) is arranged within the contraction unit (2), wherein the activation rod (28) extends axially in the drive interior space (8). [16] Actuator device according to claim 15 in conjunction with claim 11 or 12, characterized by that the activation rod (28) axially penetrates the drive interior (8) over its entire length and dips with its guide section (62) into a guide recess (63) of the first head piece (5), which opens out at an inner end face (13) of the first head piece (5) delimiting the drive interior (8). [17] Actuator device according to claim 16, characterized by that the drive channel (12) passes through the first head piece (5) and forms the guide recess (63) with its inner end section opening into the drive interior (8). [18] Actuator device according to one of claims 1 to 17, characterized bythat the activation unit (26) is designed separately from the second head piece (6) and is fastened to the second head piece (6) by a fastening device (53), wherein the fastening device (53) expediently has a fastening section (52) designed as a component of the activation unit (26) and fixed to the second head piece (6). [19] Actuator device according to one of claims 1 to 18, characterized by that the contraction hose (7) of the fluid-actuated contraction unit (2) has a hose body (22) made of a rubber-elastic material and a strand structure (23) coaxial with the hose body (22) and embedded in the material of the hose body (22) with a plurality of flexibly flexible and at the same time axially tensile-resistant fiber strands (23a), wherein the fiber strands (23a) are expediently arranged in a cross-over configuration.

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