Switching device and thread delivery device with such a switching device

Abstract

The invention relates to a switching device comprising a stationary switch, switchable by a magnetic field of predetermined strength, and a magnet arranged at a distance from the switch, wherein the distance is selected such that the magnetic field strength of the magnet is sufficiently strong to switch the switch, wherein the distance between the magnet and the switch is unchangeable, and wherein at least one ferromagnetic shielding element is provided, which is rotatably held about a rotation axis fixed relative to the magnet, such that it weakens the strength of the magnetic field in certain regions such that the magnetic field strength acting on the switch is greater than or equal to the predetermined magnetic field strength in a first rotation angular region of the shielding element and is less than the predetermined magnetic field strength in a second rotation angular region adjacent to the first rotation angular region.and that an actuating element is provided for rotating the shielding element about the axis of rotation. Furthermore, the invention relates to a thread delivery device with such a switching device.

Description

[0001] The present invention relates to a switching device comprising a stationary switch, switchable by a magnetic field of predetermined strength, and a magnet arranged at a distance from the switch, the distance being selected such that the magnetic field strength of the magnet is sufficiently strong to switch the switch. The invention further relates to a thread feeder for supplying thread to a textile machine, comprising such a switching device which serves as a thread break sensor.

[0002] Switching devices of the type mentioned above, comprising a switch that can be switched by a magnetic field of predetermined strength and a magnet, are generally known in the prior art. In such switching devices, the switch is normally actuated by changing the magnetic field strength exerted on the switch by the magnet by increasing or decreasing the distance between the switch and the magnet, such that the switch is activated. For this purpose, one of the two components is usually stationary, while the other is movable.

[0003] Furthermore, it is known in the prior art to use such switching devices as thread break sensors in yarn feeders. Thread feeders serve to supply a textile machine with yarn. The integrated thread break sensor detects a break in the yarn during feeding, whereupon the textile machine is switched off and an alarm signal is optionally issued at the thread feeder, for example in the form of a light signal, to indicate to the operating personnel at which thread feeder the thread break occurred. For example, EP 3 403 961 discloses a switching device used as a thread break sensor comprising a switch that can be switched by a magnetic field of predetermined magnetic field strength, preferably a Hall sensor, a magnet, and a rod rotatably mounted about a rotary axis and held resiliently in a predetermined position.The switch or magnet is attached to the rod, while the other component is fixed in position. Consequently, the distance between the switch and the magnet, and thus the magnetic field strength acting on the switch, varies depending on the rod's pivot position. The distance between the switch and the magnet is chosen such that the magnetic field strength acting on the switch is equal to or greater than the predetermined magnetic field strength in a first rotational angular range of the rod or the component attached to it, and less than the predetermined magnetic field strength in a second rotational angular range adjacent to the first. The switch is activated at each transition between the two rotational angular ranges. The rod is spring-loaded in the rotational angular range whose switching position stops the textile machine.During normal operation of the yarn feeder, the thread being supplied to the textile machine is guided on the rod in such a way that a tensile force exerted on the rod via the thread pulls it into a position within the other rotational angle range. If the thread breaks, the rod springs back into the rotational angle range that stops the textile machine. To allow the distance between the switch and the magnet to be varied while the rod's rotational position remains unchanged, thus varying the rotational angle ranges and consequently the so-called thread reserve, EP 3 403 961 proposes that the switch or the magnet be arranged to be adjustable along the trajectory of the other component.

[0004] Starting from this state of the art, it is an object of the present invention to create an alternative switching device and a thread delivery device with an alternative thread breakage sensor.

[0005] To solve this problem, the present invention provides a switching device comprising a stationary switch, switchable by a magnetic field of predetermined strength, and a magnet arranged at a distance from the switch, wherein the distance is selected such that the magnetic field strength of the magnet is sufficiently strong to switch the switch, characterized in that the distance between the magnet and the switch is unchangeable, and that at least one ferromagnetic shielding element is provided, which is rotatably held about an axis of rotation fixed relative to the magnet such that it weakens the strength of the magnetic field in certain areas.that the magnetic field strength acting on the switch is greater than or equal to the predetermined magnetic field strength in a first rotational angular range of the shielding element and less than the predetermined magnetic field strength in a second rotational angular range adjacent to the first rotational angular range, and that an actuating element is provided for rotating the shielding element about the axis of rotation. Unlike in EP 3 403 961 B1, the magnetic field strength acting on the switch is not changed according to the invention by changing a distance between the switch and the magnet. Rather, the magnetic field strength acting on the switch is varied by appropriately positioning the shielding element, which is movable about the axis of rotation, and the switch is activated with each transition of the shielding element from one rotational angular range to the other. The design of the switching device according to the invention has the advantage over the switching device described in EP 3 403 961 thatthat the shielding element can be arranged at a smaller distance from the axis of rotation than the component held on the rod in EP 3 403 961. Accordingly, the solution according to the invention occupies little installation space, which is desirable in many applications.

[0006] The switch can be a Hall sensor. However, a reed sensor is preferred. Reed sensors are characterized, among other things, by their ability to switch voltages up to 10,000 V, handle switching currents up to 5 A, and perform over 10 switching cycles. 9 Furthermore, the reed sensor is accessible from various locations and media such as oil, water, grease, and the like have little effect on it. In addition, unlike the Hall sensor, the reed sensor consumes no power in its passive state, as its construction is purely mechanical and contains no electronics.

[0007] According to one embodiment of the present invention, the magnet has a cylindrical outer surface, and the axis of rotation extends centrally through the magnet along its longitudinal axis.

[0008] The magnet and the axis of rotation can be connected to each other in a rotationally fixed manner, so that the magnet rotates around the axis of rotation with the actuating element, but the distance between the magnet and the switch remains constant.

[0009] The shielding element is advantageously held in a rotationally fixed position on the magnet, resulting in a very simple construction.

[0010] Preferably, at least one shielding element has the form of a ring segment, although other forms are also possible in principle.

[0011] Advantageously, a second ferromagnetic shielding element is provided, which can be moved towards and away from the magnet, particularly during translational and / or rotational movements, in such a way that the rotational angle of the first shielding element, where the first rotational angle range transitions into the second, is changed. By changing the distance between the second ferromagnetic shielding element and the magnet, the rotational angle of the actuating element, at which the switch is to be activated, can be set or adjusted within certain limits, for example, to compensate for manufacturing tolerances.

[0012] Preferably, guiding means are provided which guide the movement of the second shielding element, in particular linearly.

[0013] Advantageously, an adjusting screw is provided with which the second shielding element can be moved back and forth, so that the switching point of the switching device can be set or adjusted on site by the operating personnel.

[0014] Furthermore, the present invention provides, to solve the aforementioned problem, a thread delivery device for supplying a thread to a textile machine, comprising a switching device according to the invention serving as a thread break sensor, which is designed to stop the textile machine to which the thread delivery device supplies a thread in the event of a thread break by switching the switch accordingly.

[0015] One embodiment of a thread delivery device according to the invention is characterized in that the actuating element is spring-loaded in the rotation angle range in which the switch for stopping the textile machine is activated, and that the actuating element is designed to guide a thread during the proper operation of the thread delivery device in such a way that the actuating element is pulled into a position within the other rotation angle range by a tensile force exerted on the actuating element via the thread.

[0016] Preferably, the actuating element is rod-shaped. It can be bent once or multiple times, for example in a roof, L, or U shape.

[0017] Further features and advantages of the present invention will become clear from the following description with reference to the accompanying drawing. Therein is Fig. 1 a schematic view of a switching device according to a first embodiment of the present invention in a first rotational position; Fig. 2 a schematic view of the in Fig. 1 switching device shown in a second rotary position; Fig. 3 a schematic view of a switching device according to a second embodiment of the present invention in a first rotational position; and Fig. 4 a schematic view of a thread delivery device according to an embodiment of the present invention.

[0018] The same reference numbers refer below to identical or similarly designed components or component areas.

[0019] The Fig. 1 and Fig. Figure 2 schematically shows a switching device 1 according to a first embodiment of the present invention. This device comprises as main components a stationary switch 2, which can be switched by a magnetic field of predetermined strength, a magnet 3, a ferromagnetic shielding element 4, and an actuating element 6, in this case rod-shaped, which is rotatably arranged about an axis of rotation 5 and to which the shielding element 4 is attached at a distance from the axis of rotation 5, and which is thus also rotatable about the axis of rotation 5.

[0020] In this case, switch 2 is a reed sensor, although switch 2 can also be formed by another sensor, such as a Hall sensor or the like.

[0021] The magnet 3 is arranged at a fixed distance a from the switch 2, which is chosen such that the magnetic field strength of the magnet 3 is sufficient to switch the switch 2. In this case, the magnet 3 has a cylindrical surface and is rigidly connected to the actuating element 6. The axis of rotation 5 extends centrally through the magnet 3, corresponding to its longitudinal axis.

[0022] The shielding element 4, which is fixedly attached to the magnet 3 and has a ring-segment shape, weakens the magnetic field acting on the switch 2 in certain areas. The dashed line 7 in the Fig. 1 and Fig. Figure 2 illustrates the region in which the magnetic field strength is equal to or greater than the predetermined magnetic field strength required to switch the switch 2, assuming no shielding element 4 is present. It can be seen that, due to the constant distance a between the magnet 3 and the switch 2, the switch 2 always lies within this region 7, regardless of the rotational position of the shielding element 4. Therefore, the switching state of the switch 2 cannot change by rotating the shielding element 4 about the axis of rotation 5. The region 8, marked by the solid line, in the Fig. 1 and Fig. Figure 2 illustrates the same area with the shielding element 4 in place. It can be seen that the shielding element 4 is designed and positioned such that it weakens the magnetic field strength in certain areas, such that the magnetic field strength acting on the switch 2 is greater than or equal to the predetermined magnetic field strength in a first rotational angular range of the shielding element 4, and less than the predetermined magnetic field strength in a second rotational angular range adjacent to the first. Accordingly, when the shielding element 4 is rotated about the axis of rotation 5 by actuating the actuating element 6, the switch 2 is always switched when the shielding element 4 is moved from the first rotational angular range to the second rotational angular range, and vice versa. Fig. Figure 1 shows a rotation angle position of the shielding element 4 that lies within the second rotation angle range and in which the switch 2 is in a switching state in which no current flows through the switch 2, i.e., its contacts are open. Fig. Figure 2 shows a rotational position of the shielding element 4, in which it is positioned starting from the in Fig. The rotational position shown in Figure 1, in the direction of arrow 9, was rotated around the axis of rotation 5 towards switch 2 from the second rotational angle range to a position within the first rotational angle range. Accordingly, switch 2 is now within the area 8 marked by the solid line and was switched during the transition from the second rotational angle range to the first rotational angle range, so that current flows through it.

[0023] Fig. Figure 3 schematically shows a switching device 1 according to a second embodiment of the present invention, the structure of which is basically the same as the structure of the one described above with reference to the Fig. 1 and Fig. The switching device 1 described in section 2 corresponds to the switching device 1. The difference is that, in addition to the ferromagnetic shielding element 4, a second ferromagnetic shielding element 10 is provided, which can be moved towards and away from the magnet 3 in the direction of the double arrow 11 such that the shape of the element described in the Fig. 1 and Fig. The area 8 shown in Figure 2, identified by the solid line, is changed. With the second shielding element 10 in the position shown here, area 8 is different from the area shown in the Fig. 1 and Fig. 2 shown area 8 around the in Fig. Section 12, shown hatched in Figure 3, is reduced in size. This changes the rotational angle of the first shielding element 4 at which the first rotational angle range transitions into the second rotational angle range, and thus the rotational angle at which the switch 2 is activated. In this embodiment, the second shielding element 10 is positioned between the switch 2 and the magnet 3 and can be moved in a direction transverse to an imaginary connecting line between the switch 2 and the magnet 3. In the illustrated embodiment, guide means 13 are provided which guide the movement of the second shielding element 10 linearly. For the movement of the second shielding element 10, a [missing information] is required. Fig. 3 adjusting screws (not shown in detail) are provided, with which the second shielding element 4 can be moved back and forth in the direction of the double arrow 11.

[0024] Fig. Figure 4 shows a yarn delivery device 14, which serves to supply a yarn F to a textile machine (not shown in detail). This is equipped with a switching device 1 according to the invention. Fig. 1 and Fig. 2 or according to Fig. 3, which in this case functions as a thread break sensor. The thread delivery device 14 has a support unit 15, which essentially comprises a C-shaped support arm 16, a housing 17, and a mounting clamp 18. The thread delivery device 14 is further equipped with a thread delivery wheel 19, which is arranged at a lower end of a shaft 20 extending through and supported in the support unit 15. At least one pulley 21, in this example two pulleys 21, and a switching clutch with a handle 22 are arranged on the shaft 20.

[0025] In the course of the thread F in front of the thread delivery wheel 19, an entry eyelet 23, a knot catcher 24, a thread brake 25 and an entry sensor 26 are arranged on the support unit 15.

[0026] In the course of the thread F after the thread feeder wheel 19, a first discharge eyelet, the actuating element 6 of the switching device 1 according to the invention, and a second discharge eyelet 28 are arranged on the support unit 15. While the two discharge eyelets 27 and 28 are fixedly held on the support unit 15, the actuating element 6, together with the magnet 3 and the first shielding element 4 held on them, is rotatably held about the axis of rotation 5 and is spring-loaded within the range of rotation in which the switch 2 is closed to stop the textile machine. The switching point, i.e., the transition between the two with reference to the Fig. 1 and Fig. The rotational angle position of the first shielding element 4, forming the rotational angle ranges described in 2, is in Fig. 4 marked with the reference symbol S1.

[0027] During operation, the thread F, fed in the direction of arrow 29, is guided through the infeed eye 23, the knot catcher 24, the thread brake 25, and the infeed sensor 26, wrapped several times around the thread feeder wheel 19, and from there through the first outfeed eye 27, then back around the actuating element 6, and then forward again to the second outfeed eye 28, from where the thread F is fed to the textile machine. In this process, the actuating element 6 is pulled by the tensile force exerted by the thread F, against the spring force, from the switching position S1 into an operating position B, and thus into the range of rotation in which the switch 2 is in a switching position in which it is not activated to stop the textile machine.If the thread F breaks downstream of the thread feeder 19, the spring-loaded actuating element 6 is automatically rotated clockwise beyond the switching position S1 under the influence of the spring force, thus activating the switch 2 to stop the textile machine. Simultaneously, an alarm signal can be issued, for example in the form of a light signal, indicating at which thread feeder 14 the thread breakage occurred. The operator can then rectify the thread breakage.

[0028] Is switching device 1 one of those described in Fig. As shown in Figure 3, the rotational angle of the first shielding element 4, where the first rotational angle range transitions into the second rotational angle range, and thus the switching position S1, can be changed by altering the position of the second shielding element 10, in this case by the operator operating an adjusting screw 29. For example, if the second shielding element 10 is moved from a position in which it is located in Fig. When position 4 is located, moving towards magnet 3, the switching position S1 is entered. Fig.Moving position 5 further to the left to switch position S2 results in a larger yarn reserve. This means that switch 2 triggers later from operating position B. This can be desirable to ensure that minor changes in yarn tension downstream of the yarn feeder wheel 19, which regularly occur in many textile machines, do not immediately shut down the machine. Adjusting the position of the second shielding element 10 can also compensate for manufacturing tolerances of the switching device 1.

[0029] The use of a switching device 1 according to the invention as a thread break sensor of a thread delivery device 14 is characterized by the fact that it requires only a very small installation space, that it has a very long service life and is also insensitive to changing temperatures and contamination.

[0030] It should be clear that the embodiments described above serve only as examples and are not to be understood as limiting. Rather, changes and modifications are possible without leaving the scope of protection defined by the accompanying claims. REFERENCE NUMBER LIST 1 switching device 2 switches 3 Magnet 4 Shielding element 5 axis of rotation 6 Actuating element 7 Area (dashed line) Area 8 (solid line) 9 Arrow 10 second shielding element 11 Double Arrow 12 hatched section 13 Management tools 14 Thread delivery device 15 carrying unit 16 support arm 17 cases 18 Mounting clamp 19 Thread delivery wheel 20th wave 21 Pulley 22 Handle 23 Inlet eyelet 24 knot catchers 25 Thread brake 26 inlet sensors 27 first outlet eye 28 second outlet eye 29 Adjusting screw a distance F thread S1 switching position S2 switch position B Operating position QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] EP 3 403 961 [0003, 0005] EP 3 403 961 B1

[0005]

Claims

Switching device (1) comprising a stationary switch (2) switchable by a magnetic field of predetermined strength and a magnet (3) arranged at a distance (a) from the switch (2), wherein the distance (a) is selected such that the magnetic field strength of the magnet (3) is sufficiently strong to switch the switch (2), characterized in that the distance (a) between the magnet (3) and the switch (2) is unchangeable, and that at least one ferromagnetic shielding element (4) is provided which is rotatably mounted about a rotational axis (5) fixed relative to the magnet (3) such that it weakens the strength of the magnetic field in certain areas.that the magnetic field strength acting on the switch (2) is greater than or equal to the predetermined magnetic field strength in a first rotation angular range of the shielding element (4) and less than the predetermined magnetic field strength in a second rotation angular range adjacent to the first rotation angular range, and that an actuating element (6) is provided for rotating the shielding element (4) about the axis of rotation (5). Switching device (1) according to claim 1, characterized in that the switch (2) is a Hall sensor or a reed sensor. Switching device (1) according to claim 1 or 2, characterized in that the magnet (3) has a cylindrical outer surface, and that the axis of rotation (5) extends centrally through the magnet (4) along its longitudinal axis. Switching device (1) according to claim 3, characterized in that the magnet (3) and the axis of rotation (5) are connected to each other in a rotationally fixed manner. Switching device (1) according to claim 4, characterized in that the shielding element (4) is held non-rotatably on the magnet (3). Switching device (1) according to one of the preceding claims, characterized in that the at least one shielding element (4) has the form of a ring segment. Switching device (1) according to one of the preceding claims, characterized in that a second ferromagnetic shielding element (10) is provided which can be moved towards and away from the magnet (3) in such a way that the rotational angular position of the first shielding element (4), in which the first rotational angular range transitions into the second rotational angular range, is changed. Switching device (1) according to claim 7, characterized in that guide means (13) are provided which guide the movement of the second shielding element (10) in a particularly linear manner. Switching device (1) according to claim 7 or 8, characterized in that an adjusting screw (29) is provided with which the second shielding element (10) can be moved forwards and backwards. Thread delivery device (14) for supplying a thread (F) to a textile machine comprising a switching device (1) serving as a thread break sensor according to one of the preceding claims, which is designed to stop the textile machine to which the thread delivery device (14) supplies a thread (F) in the event of a thread break by switching the switch (2) accordingly. Thread delivery device (14) according to claim 10, characterized in that the actuating element (6) is spring-loaded in the rotation angle range in which the switch (2) switches to stop the textile machine, and that the actuating element (6) is designed to guide a thread during the proper operation of the thread delivery device (14) in such a way that the actuating element (6) is pulled into a position within the other rotation angle range by a tensile force exerted on the actuating element (6) via the thread (F). Thread delivery device (14) according to claim 10 or 11, characterized in that the actuating element (6) is rod-shaped.

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