Extraction device, particularly for mining, and method for controlling the extraction device

Translation of description of equivalent WO 2009033622 A2

Title: recovery plant in particular for mining and method of driving the recovery unit

The invention relates to a recovery plant particularly for mining, having a first drive station and a second, preferably by means of a clamping device tensionable drive station, having with mounted in the drive stations sprockets, a chain links and movable by means of motor driven sprockets and / or deflectable drive chain, which extends between the sprockets in an upper run and a lower run, and at least one sensor device for detecting at least one chain condition of the drive chain in the upper run or the lower run. The invention also relates to a method for driving a recovery system particularly for mining, having a first drive station and a second, preferably tensible by means of a clamping device drive station, having with mounted in the drive stations sprockets, a chain links and movable by means of motor driven sprockets drive chain which extends between the sprockets in an upper run and a lower run, with at least one sensor device for detecting at least one chain condition of the drive chain in the upper run or the lower run, and having a control device, which is supplied with the signals of the sensor device and with which the extension state of the clamping device and / or the drives of the drive stations can be controlled.

For the operation of a production plant with a circumferential or a reversibly operating drive chain, it is of enormous importance to estimate the chain condition of the drive chain and in particular the chain pre appropriate measures or to check. Basically, optical, electrical, magnetic and mechanical sensor devices were already proposed this gen, should provide the metrics that make up the Kettenspannungs- state to be derived and derived by appropriate algorithms control parameters for the clamping device, or also for the drive motors of the drive devices.

In DE 34 06 519 Al it is proposed to use a magnetically operating sensor device to detect magnetic chain tension with tensioned drive stations. In DE 34 06 519 this is provided a magnetic field generator which is allocated to the running out of the drive station run in the warp direction. The intended to measure the chain tension in the upper strand magnetic field generator is arranged in the base plate and to measure the chain tension provided in the bottom strand magnetic field generator is arranged in the base plate of the drive station above the lower strand to a detuning of the magnetic field which due to a change in distance between results to be measured drive chain and the chain links, to detect. In addition to the hanging chain and the distance from scratches a conveyor chain or a change in the chain link distances in combination with a hanging chain control is to be realized. The measuring principle in DE 34 06 519 is based on generating a directed magnetic field that is detuned by different depths in the magnetic dipping chain links, wherein the detuning of the sampled magnetic field to be metrologically evaluated. Since the magnetic encoder including the measuring device in the bottom plate of the outgoing strand is arranged, there occurs a high wear, which allows only a short service life of such a magnetic measuring system. Therefore, the technical implementation of the known from DE 34 06 519 Al system for hanging chain detection and other chain states could not be further developed for series production.

The object of the invention is to provide a production plant and a method for driving a recovery system that allow reliable detection of the chain condition of the drive chain with a contactless sensor means and have high system security is a significantly longer service life. These and other objects are achieved in a recovery plant according to the invention that each sensor device comprises a formed by a magnetic field generator sensor and a multi-magnetic field detectors provided detector array as a detector, said detector and transmitter designed side of a passageway for the scanned run of the drive chain or are positioned. A system technical advantage in attracting investment of the invention is that the sensor device is not a detuning of the magnetic field to the magnetic field generator and detector metrologically evaluates for a different spacing of the links, but a change in position or change in height of the driver or chain link scanning transversely to the direction of the drive chain. In the recovery system of the invention, the magnetic field is introduced into the drive chain, and for each magnetic field detector of the detector array, a measurement signal is detected. If the position of a chain link or a driver within the sensor array relative to its position at the previous passage or relative to a defined zero position can be deduced whether the chain link and the driver in the area of ​​the detector array moves up or down. If at the same time a time signal for each carrier or each link detected, so also a different distance of links or carriers can be detected each other, what other conditions such as chain chain wear, Kettenverdrillung or the like. can be determined.

Designed as a detector array detector and the timer for the magnetic field can be arranged on the same side next to each other. In a preferred embodiment the detector and transmitter are arranged opposite to each other so that consequently the transmitter initiates the magnetic field on the one side in the chain links or carrier and the magnetic field detectors of the detector array to scan the signal transmitted from the chain links or carriers magnetic field on the other side of the passage. To enable a reliable detection of particular hanging chains, is particularly advantageous if the detector array extends with several detectors on the height of the gangway. In the particular preferred embodiment, configuration, the detector array at a plurality of juxtaposed magnetic field detectors and a plurality of stacked magnetic field detectors to detect the transverse to the running direction of the drive chain transmitted or forwarded from the scanned chain link or carrier alternating magnetic field in a sufficiently large area. To simplify the computational complexity, in this case, the magnetic field detectors can be arranged in rows and columns at constant intervals. Due to the two-dimensional arrangement of the magnetic field detectors in the detector array measurement and sampling of the transmitted magnetic field with magnetic field detectors can be carried out, if necessary, the only measure and detect the horizontal components of the transmitted magnetic field.

it if the detector array and / or the producers arranged for the magnetic field in the side walls of a machine frame or the side walls of a chain wheel well of the drive unit, in particular incorporated is particularly advantageous. In the side walls or side walls neither the detector nor the producer of the magnetic field are subject to significant mechanical wear, since the chain links or dogs do not come even with hanging chain or maintenance in contact with the transmitter and detector. In two side walls or side walls is usually enough space is available to integrate a detector array and a transmitter for the magnetic field. To verweiden interactions with the surrounding structure formed from the machine frame, the detector array and / or the sensors are preferably disposed in a housing or a support structure made of nonmagnetic material. The material may in particular brass, bronze, copper, aluminum, titanium, austenitic steel or alloys hereby made of ceramic or made of plastic. The material used and the material alloys used should meet all the requirements for explosion protection (flameproof, Gas explosion protection) for the respective application.

With the magnetic field generators can be produced according to one embodiment of the invention, a static, temporally constant magnetic field. According to an advantageous alternative embodiment, Alternating magnetic field generators are used as a donor to produce a dynamic alternating magnetic field. By using alternating magnetic field generators as a donor for the magnetic sensor device a modulated magnetic field is used to measure used, which prevents measurement errors due to different magnetic preferred directions of the chain links to be scanned or entrainment occur. Investigations have shown that the chain links and carriers used in drive chains of conveyors (scraper chain) show with magnetization perpendicular to the direction of the transmission chain significantly different magnetic flux densities and reinforcements of the emitted from the magnetic generator magnetic field. When using alternating magnetic field generators, the dependence is avoided by the preferred magnetic direction of the chain link to be scanned or the driver, since the alternating magnetic field is sampled at the detectors in the detector array. In the particularly preferred embodiment of the encoder or magnetic alternating field generator is formed by a rotatable or rotating magnet. The rotation speed of the magnets can be at least 100 U / min and up to 1000 U / min or more. More preferably, the magnet having a magnetic field strength of at least 0.5 T (Tesla). The rotatable or rotating magnet may be in particular a permanent magnet. The transmitter can in this case one or even obtained several rotatable or rotating magnets to achieve a high AC frequency of the alternating magnetic field even at low speed. The plurality of permanent magnets can be arranged in particular in a rotatable carrier of nonmagnetic material. To satisfy the explosion protection, the encoder for the alternating magnetic field preferably a hydraulic rotary drive, in particular a hydraulic motor with flow control valve for speed adjustment, on. The hydraulic medium can be diverted from the central, underground hydraulic supply for the expansion shields or return equipment and reduced the pressure level by means of a pressure control stage to an allowable pressure for the hydraulic motor. The switching on and off can be effected via piloted multiway valves. It is particularly advantageous if the rotary drive for the timer is assigned a rotational angle sensor to the current rotational angle of the motor dulators to capture and deliver to the evaluation and control unit.

In a further product variant, the magnet or to a plurality of magnets of the transmitter form a magnet arrangement, the position and / or orientation is variable relative to the magnetic field sensor to generate a variable especially in the magnetic field strength magnetic field. The encoder may comprise a magnet arrangement with several concentric about a central axis arranged ring magnets for this purpose preferably, the ring assembly by means of an actuator about the central axis is rotatable. It is particularly advantageous if the magnet assembly can be positioned by means of the actuator in different Verdrehlagen. This can be achieved for example by a self-locking actuator with high reduction ratio, which may consist of an electric actuator, in particular, the current is switched off in the desired rotational position.

The recovery plant can be designed as conveyor with carriers in the drive chain, and each drive station then has possibly only a sensor device, which is assigned to the strand, which expires in chain direction respectively behind the sprocket from the drive station. Since drive-in conveyors and working control technology usually with a main drive and an auxiliary drive, a sensor device in the lower run of the prime mover and a second sensor device in the upper strand of Hilfsan- drive would then be arranged. Alternatively, it may be a recovery unit such as a plow system with a reversibly movable drive chain, in which case each drive station comprises two sensor devices, one of which is in each drive station one sensor device the upper run and a sensor means associated with the lower run or is assigned. In reversing the moving drive chains, the drives of the drive stations have to pay most of the work, depending on the direction of the extraction machine, so hanging chain can occur both before and behind the chain in each drive station. However, it may also in conveyors each Trum be assigned in the drive station one sensor device.

More preferably, the transmitter can be assigned on the same side of the passage of magnetic field sensors for detecting the magnetic field generated by the transmitter real as a reference.

The aforementioned object is achieved in a method according to the invention in that each sensor device generates a static magnetic field or a dynamic alternating magnetic field which is sensed by a formed of a plurality of magnetic field detectors detector array, wherein the scanned run of the drive chain between the magnetic field generator and the detector array is passed and from a change in the position of erfass- th in field detector magnetic field or alternating magnetic field of the chain condition of the drive chain is determined.

In the method according to the invention is particularly advantageous when each magnetic field detector of the detector array samples the output from the encoder and transmitted by the drive chain, and consequently of the chain links or of the carriers magnetic field or alternating magnetic field and from the position of the or of the maximum magnetic field strength investigating magnetic field detector / s chain condition, in particular the position of the chain links or driver, is determined. It is particularly advantageous if in the evaluation and control unit, the indicators such as are recorded the speeds of the drive motors of the drive stations and a speed control and / or a change in the stress state of the clamping device are introduced in response to the detected chain condition. The determined with the magnetic sensor device chain state, however, can also be used without speed detection for activating the clamping device. According to a further embodiment of the method with a dynamic alternating magnetic field generating transmitter can use the timer associated magnetic field sensors, real, produced by the donor alternating magnetic field are recorded and supplied as a reference value of the evaluation unit and / or the angle of rotation of a rotary drive for the transmitter is detected and the reference value of evaluation unit supplied. With these reference values ​​the measured result can be checked in addition to the presence of measurement errors.

Since a single driver or a single chain link, such as measurements of the inventors have shown, can have not only different magnetic preferred direction, but even with identical magnetization can occur different changes of the introduced magnetic field or alternating magnetic field, and there may also appear interactions between adjacent carriers or chain links , is in the particularly preferred embodiment initiated every time the drive train, a reference or Kalibrierdurchgang in which each link or for each driver, a reference value for the basic magnetization is determined, which is compared in the operation with the currently detected by the detector array measurement value in order therefrom to determine a change in the chain condition, such as a change in position or increasing wear of the individual chain links or driver.

Further advantages and embodiments of the invention will become apparent from the following description of embodiments schematically shown in the drawing. In the drawings:

FIG. 1 schematically simplified a schematic diagram of an executed as promoters recovery plant according to the invention for underground mining;

FIG. 2 highly schematically simplified a drive part of a drive unit for the production plant of Figure 1 with built-in sensor device.

Fig. 3 AC schematically highly simplified in a single system image, the position detection in the magnetic sensor device according to the invention; . Fig. 4 is a schematic diagram similar to Figure 1 a constructed as a plow system recovery plant with an inventive sensor device;

Figure 5 AC capturing different chain positions in the plow system of FIG. 4.

Fig. 6 schematically greatly simplified perspective view of an embodiment of an alternating magnetic field generator;

Fig. 7 schematically greatly simplified perspective view of an exemplary embodiment of a magnetic field generator with variable magnetic field, partially broken away; and

Fig. 8 shows the magnetic field generator of FIG. 7 in plan view.

FIG. 1 shows a schematic system diagram of a designated overall by reference numeral 10 conveyor system for underground mining. The conveyor system 10 includes in a known manner, a first drive station 1 with a schematically illustrated drive motor 2 and a sprocket 3 and at the other end of the conveyor system 10, a second drive station 4 again with a sprocket 5 and associated drive motor 6. The drive motors 2 and 6 can basically each have suitable for the intended use and the like configuration as synchronous motors, frequency converter motors. be designed and transmission control devices, overload clutches, and the like. include. Between the two sprockets 3, 5 an endless scraper chain 6 circulates in the direction indicated by the arrow F direction of conveyance, said material being in obtained by suitable extraction tools in an underground face, in an upper run 6A means in FIGS. 2 and 3A-C schematically indicated pushers 11 is transported in the direction of the drive station 1, which forms the main drive here. The upper run of the circulating on the sprockets 3, 5 drive chain is in FIG. 1 with 6A and the return run or Leerlauftrum the drive chain 6 with Numeral 6B respectively. Given an operating conveyor one drive, to which the upper strand 6A tapers, the larger drive power, making therefore a priority in the lower run 6B behind the sprocket 3 of the drive station 1, but also in the bottom strand 6A behind the sprocket 5 of the drive unit 4, the risk of the occurrence of hanging chain consists. To different voltage states of the drive chain 6 to compensate, in the conveyor system 10 to the auxiliary drive, hence the drive station 4, a hydraulic tensioning device 7 associated with which the distance between the sprockets 3, 5 of the drive stations 1, 4 can be changed. The extension or retraction of the clamping device 7 is effected in dependence on a direction indicated by the line 8 control signal of a hydraulic control. 9

In the conveyor system 10 is, as shown in FIG. 3A-3C show a designed as a double-chain drive chain 6 with horizontal chain links 12 and vertical chain links 13 are used, are attached to which at certain intervals driver (scratches) 11th In order to recognize the occurrence of hanging chain to the drive chain 6 or the occurrence of wear on the chain links 12, 13 or the driver 11 in the conveyor system of FIG. 1, is two drive stations 1, 4 a in FIG. 1 with 20 indicated sensor device assigned. The sensor device 20 is associated with the main drive, moreover at the drive station 1 in Fig. 1, the lower run 6B in chain direction in the outlet behind the sprocket 3 and when the auxiliary drive forming drive station 4 in the chain running direction F at the outlet of the chain wheel 5 the upper run 6A. Both sensor devices 20 are preferably constructed identical to each other and comprise a generator, which generates a magnetic alternating field in the described embodiment and is designated in FIGS. 2 and 3A-3C schematically with reference numeral 21, and a detector array 22 having a plurality of adjacent and superposed magnetic field detectors 23 as a detector for the light emitted by transmitter 21 alternating magnetic field. The alternating magnetic field sensor 21 is arranged in one of the two side plate 14 on one side of a passage 15 for the driver 11 as well as the chain links 12, 13 and the detector array 22 is the timer 21 in the other side wall 15 opposite. As Fig. 2 shows schematically the forming a main drive drive station 1 shows, here are the magnetic encoder 21 and the detector array 23 in the side panels 14, 15 installed in the area of ​​the lower run 6B of the drive chain 6, and in a position, in the position indicated by the bulge 6 'in Fig. 1 Hängkette due changing the height of the driver 11 can be detected relative to the tangential outlet of the sprocket. 3 Both the transmitter 12 and the detector array 22 may be arranged in a housing of non-magnetic material. However, it might also be the side walls at least partially made of a suitable, non-magnetic material. The alternating magnetic field generator 21 can advantageously consist of a permanent magnet or, if no requirements have to be met on explosion protection, composed of an electromagnet which is attached to a preferably variable speed motor and with rotational speeds of up to 1000 rev / min is rotated to a modulated produce or dynamic magnetic field (alternating magnetic field) for detection with the detector array 22nd The rotary drive for the magnet or it may be in particular a hydraulic motor (not shown) act, which is offset due to the flow of hydraulic fluid in rotation. The detector array 22 in turn comprises a matrix with a suitable number over and juxtaposed magnetic field detectors 23, so 23 that initiated by the encoder 21 on the one side in the driver 11 magnetization and temporary magnetisation can be sampled at each of the individual magnetic field detectors.

Figs. 3A, 3B and 3C schematically illustrate the position of a follower 11 in three different positions relative to the detector array 22. In the uppermost diagram in Fig. 3, a driver 11 is shown, the passage 15 between the alternating magnetic field generator 21 and the detector array 22 transferred with the matrix-like and juxtaposed magnetic field detectors 23 in the middle range, ie with normal chain tension, happened. The individual detectors 23 in the detector array 22 detect different magnetic field strengths, from which the indicated central location can be calculated. The self-adjusting because the emitted by the encoder 21 alternating magnetic field on the driver 11 magnetic fields are illustrative as Magnetic field lines indicated schematically. In Fig. 3B, the driver 11 is moved upward due Ü berhöhter chain tension. With the magnetic field lines indicated that the magnetic field generated by the alternating magnetic field 21 has moved in the carrier 11 at essentially the same magnetic field strength up, so higher lying magnetic field detectors 23 the maximum deflection of the field strength detected animals, while the underlying magnetic field detectors 23 detect a much smaller magnetic field strength. Since a modulated alternating magnetic field is introduced into the driver 11, detect course also the magnetic field detectors 23 a corresponding to the rotational frequency of the alternating magnetic field generated modulated magnetic field. Due to the sufficiently high rotational frequency of the alternating magnetic field a sufficient number is nevertheless detected at amplitude change of the alternating magnetic field to the current situation of the driver 11 safe and free to be able to identify 11 of magnetization influences the driver during the passage of the driver 11th Fig. 3C shows the state before or upon the occurrence of hanging chain. The driver 11 is in a position at the lower end of the detector array 22, which is why the lowest lying magnetic field detectors 23 detect the maximum amplitude of the change introduced into the driver 11 through the encoder 21 alternating magnetic field. The respective displacement of the magnetic field is indicated by the different layers of the magnetic field lines of the magnetic field on the donor 21st

Reference is made to Figure 1. Again. The determined with the detector array 22 signals for the individual magnetic field detectors 23 are supplied to a master control unit 50th Over the indicated to the signal lines 25 in FIG. 1, signal lines and the current rotational speed of drive motors 2 and 6 of the control unit 50 can be supplied. the evaluation and control unit is able to generate 50 control signals which are supplied to the hydraulic control unit 9 from via signal lines 25 supplied measurement data from the detector array 22 as well as the current rotational speeds of the driving motors 2, 6, in order via the signal line 8, an extension or retraction of the hydraulic tensioning device for effecting 7 and the position of the chain wheel 5 at the auxiliary drive 4 for path margins of Hängkette or to minimize the chain tension to change in to taut drive chain. 6 The control and evaluation unit 50 can also output control signals in parallel, for the drive motors 2, 6 to prevent the occurrence of hanging chain or heavy chain tension by changing the respective speeds of the drive motors 2,. 6

In the embodiment in FIG. 1, two further sensor devices 30 are indicated, can be detected via the optionally further chain conditions both in the drive station 1 as well as in the drive station 4. In the main drive 1 further sensor device 30 is the upper strand 6A in the feed before the sprocket 3 and to drive the auxiliary forming drive unit 4 is the sensor device 30 is arranged the tapering on the sprocket 5 strand 6B. The measurement principle of the sensor device 30 in the embodiment shown is again based on the introduction of a modulated magnetic field (alternating magnetic field) in the driver and the sampling of the picked up by the driver when passing through the magnetic field of the Magnetwechselfeld- generator modulated magnetic field with a sensor array 32 having a plurality of magnetic field detectors 33. The measuring signals of the detector array 32 may be supplied via signal lines 35 of the evaluation and control device 50 in turn.

Fig. 4 shows a schematic diagram of the use of the same system technology at a plow system 110 for underground mining. A mining plow 160 is reciprocated by means of an in principle endless plow chain belt 106, consisting of interlocking comprehensive vertical and horizontal chain links (112, 113, Fig. 5), reversing from a driving station 101 to another drive unit 104, or vice versa, back or, as with the double arrow R indicated in FIG. 4. The drive station 101 has not shown drive motors and a sprocket 103 for the plow chain 106 and the drive unit 104 has a sprocket 105 and a chuck 107. Depending on the direction of movement of the planer 160 of one of the two drives is a main drive and the other the respective auxiliary drive. The plow chain 106 in turn forms an O- Bertrum 106A and a lower run 106B, depending on the direction of R the planer 116 form the pull or return strand. Since hanging chain and / or excessive chain tension both in the inlet and in the outlet of each sprocket 103, depending on the direction of rotation R of the plow body can occur 160 in the plow system 110 four i- dentische sensor devices 120 are provided, on the one hand a detector array 122 with a sufficient have number of arrayed magnetic field detectors 123 and are arranged laterally of the passage for the chain 106th Each detector array 122 is assigned to each one in Figs. 5A, 5B and 5C schematically shown alternating magnetic field generator 121 which is opposite to the detector array 122 and also laterally of the passage 115 is arranged for the drive chain belt 106th Since in the plow system 110 is a variation of preferably introduced into the horizontal chain links 112 alternating magnetic field is detected by the magnetic field detectors 123 in the detector array 122, the distance between the generator 121 and the detector array 122 is much lower than in the previous embodiment. In addition, the generator 121 and the detector array 122 can be an alternative to the machine frame also directly in side walls of a planing box, not shown, in which the chain wheels are mounted 103 and 105, respectively, incorporated in order to detect the change in the modulated magnetic field in a relatively protected location. Similar to the previous embodiment, a displacement of the plow chain 106 upward due to a detection of the maximum amplitude of the alternating magnetic field with higher-lying magnetic field detectors 123, as indicated in Fig. 5B, respectively indicated with deeper magnetic field detectors 123, as shown in Fig. 5C, is detected, depending on whether the chain upwards or hanging chain against a middle position moved due to excessive chain tension down. Also, in the plow system 110, a control and evaluation unit 150 is provided, which at least all the measured values ​​of the four detector arrays 122 of the sensor devices 120 are supplied. Signal feed can take place, as is indicated by the radio transmitter 126 and radio receiver 127 in Fig. 4 either via the signal lines 125, via a system bus or wireless via radio. It will be appreciated that the radio receiver 127 may be also designed for bidirectional data transmission. In order optionally to detect the magnetic sensor devices and chain wear or Mitnehmerverschleiß, and to detect hanging chain with high degree of certainty, a reference or calibration run can be performed every time the extraction plant, in which each link or each horizontal chain link with a plow system or for each driver in a conveyor system, a reference value is determined. In the best case this case, the evaluation and control device is known how many horizontal chain links and carriers are incorporated in the system. can be obtained by storing a reference value for each carrier or each chain link, as this changes the individual magnetic field of each carrier and each horizontal chain link with increasing wear, from a comparison of reference values ​​with reference values ​​prior calibration runs, or by prolonged operating time, comparing the current values ​​with the reference values ​​from a change of the transmitted magnetic field pass through the magnetic alternating field encoder, the current wear are determined to take timely a maintenance interval before a chain terminator crack or the like. occurs. The sensor device used in the extraction plant is therefore not limited to the application for suspension chain detection.

The exemplary embodiments show the schematic arrangement of alternating magnetic field generator and detector array. In the detector field also significantly more than nine or twelve magnetic field detectors can be arranged, for example, 16 or 27 magnetic field detectors in order to increase the resolution of the system. The magnet used to generate the modulated magnetic field can be a powerful permanent magnet (super magnet) for example made of neodymium-iron-boron (NdFeB) or other suitable material for super magnets sufficiently high magnetic field strength of eg IT, which up to a frequency of eg is driven to 1,000 U / min to produce an alternating magnetic field with a sufficient number on amplitude changes when running through the driver or the chain links. The rotation angle can be detected in this case as a reference value. The transmitter may optionally also allocated on the same side of the passage of magnetic field sensors be. The introduced with the alternating magnetic field in the driver or chain links magnetization state differs markedly from the initial magnetization state of the driver or chain links, so that the dynamic, modulated alternating magnetic field can be discriminated securely by the initial magnetization of the driver when passing a sensor field. The sensor system should measure at least two directions and preferably in all three directions field and having a sufficient number of magnetic field detectors.

Fig. 6 shows schematically an embodiment of an alternating magnetic field generator 221 as a sensor for a sensor device according to the invention. The alternating magnetic field generator 221 has a preferably box-shaped, can be inserted into a receiving recess in the side walls as a machine frame housing 250, is mounted in which a rotating shaft 240, are mounted rotatably on the multiple, stacked block magnets 241st The arrangement of this consisting of block magnet permanent magnet 241 is preferably performed with a matching orientation of the magnetization. In the illustrated embodiment all poles marked with N and all poles marked with S the block magnets 241 are each aligned over one another. To drive the rotary shaft 240 and associated with this magnet 241 in the housing further includes a hydraulic actuator 242 is arranged, for example, which is coupled to a gear 243 on the output shaft 244 a gear is arranged 245, which in turn rotationally fixed to a connected to the rotating shaft 240 gear 246 meshes. The hydraulic drive can in particular of a hydraulic motor with flow control valve (not shown) are made for speed adjustment. During a rotation of the rotary shaft 240 is formed over the entire height of the alternating magnetic field generator 221, a dynamic alternating magnetic field, which can be introduced into the entrainment means of the drive chain and detected at the opposite end of the carrier with the sensor device.

The foregoing description of the figures was carried out for a production plant with a sensor device, which has a magnetic alternating field generator as a donor for a dynamic magnetic field. The donor could also produce a static magnetic field with a detector field in a recovery plant, as described above, scanned. FIGS. 7 and 8 show for such a magnetic field generator 321, with which a static, but variable magnetic field can be generated, by way of example one embodiment. Inside a box-shaped housing 350 are on the sides, of which one of the machines cheek and the other passage is in operational use faces in the drive station, each pole plates 351, 352 arranged in preferably soft, magnetic ferrous material, between which a magnet set 348 from here more, arranged above one another, diametrically magnetized ring magnet 341 is arranged. The ring magnets 341 are arranged such that all poles designated N and S poles are superposed each approximately aligned. All ring magnets 341 are fixed to a magnet roller 340, which can be turned to the pole plates 351, 352 relatively by means of a in Fig. 8 schematically indicated and, for example via gears coupled thereto rotary actuator 342 in its orientation in order depending on the relative position of the magnetic package 348 to the pole plates 351, take 351 different strong magnetic fields in these and thus also in the passing driver or chain links. Turning the magnetic shaft preferably takes place only at a calibration run, whereas the magnetic wave is set in operation via the off actuator and the effective reduction ratio. With the magnetic field generator 321 as a donor of the sensor device, a static, non-modulated magnetic field can be generated, which is introduced from the one side of the machine frame in the carrier and is scanned on the other side of the machine frame with the detector array. By changing the orientation of the magnetic package 348 relative to the passage and the detector array, the measurement can be made in each case with an optimum magnetic field.

The invention is not limited to the embodiments shown schematically. At least one of the drive stations could also be a non-driven reversing sections, with the sprocket, the drive chain is only deflected.