Title of Invention

STOPPER MAGNET

Abstract

A stopper magnet (M) for yarn feeding devices includes a central armature (A) which is adjustable axially from a first position by a magnetic coil (C1, C2) into a second position against a stop (7, 8), and a metallic housing (H) containing the coil (C1, C2), the armature (A) and the stop (7, 8), the housing comprising an outer wall and upper and lower cover walls. The housing (H) comprises a tube section (2) forming the outer wall and two separate end parts forming the cover walls and contacting the ends of the tube section (2). The end parts (3, 4) are interconnected by at least two tensioning elements (T1, T2) located outside of the tube section (2).

Full Text

STOPPER MAGNET The invention relates to a stopper magnet according to the preamble of claim 1. In a yam feeding device for jet weaving machines the stopper magnet constitutes the actuator for the stopper pin which is needed to measure the pick length for each pick. The stopper pin e.g. co-operates with the storage body of the yam feeding device and is moved by the stopper magnet between a position retracted from the storage body and a position where it engages into the storage body. As long as the stopper pin is in the retracted position yam windings can be drawn off from the storage body. In the extended position the stopper pin is blocking the yarn against withdrawal. The stopper magnet moves the stopper pin extremely rapidly between both positions. In some cases the stopper magnet is only controlling the movement of the stopper pin into one position, while the movement into the other position is controlled by a spring. The respective position of the stopper pin is defined by a stop at which the armature and/or stopper pin is caught The impact at the stop needs to rapidly dissipate a considerable amount of energy. For that reason an impact damper e.g. a washer made from plastic material, may be placed between the stop and the armature and/or the stopper pin. Experience in practice shows that the impact damper or the stop is the weakest link in the kinematic system of the stopper magnet. The impact damper and/or the stop wears and needs to be replaced then. This effect limits the service lifetime of the stopper magnet undesirably. The stopper magnet known from US-A-4,632,155 has a housing consisting of a pot-shaped lower part and a cover cap fixed to a mounting flange at the upper end of the pot-shaped lower part. The bottom wall of the pot-shaped lower part is integrally formed with the stop for the armature. The cover cap forms another stop for defining the retracted position of the stopper pin. The cover cap is clamped to the moulting flange by fastening elements which are distributed around the circumference of the mounting flange. A ring-shaped travel arresting plate is located between the cover cap and the mounting flange. The design of the housing of the stopper magnet results in a very rigid structure. The impacts at both stops thus cause excessive wear at the stops or at the armature itself and restrict the service lifetime of the stopper magnet undesirably, because the impacted energy has to be dissipated by the armature and the stop only. It is an object of the invention to provide a stopper magnet as mentioned above which has a significantly longer or extended service lifetime. Said object is achieved by the features of claim 1. The design of the housing consisting of three separate components, namely the tube section and the two end parts, and the location of the tensioning elements outside of the tube section such that the tensioning elements interconnect the end parts where the end parts protrude outwardly, surprisingly results in an axial yieldability of the housing. The housing yields in axial direction such that the respective stop is able to also yield axially whenever an impact is to be taken. The somewhat elastic response behaviour of the respective stop as allowed by the axial yieldability of the housing and the tensioning elements in combination reduce wear of the stop and/or of the armature. When, as conventional, an impact damper, e.g. a washer made from plastic material, is placed between the armature and the stop, also wear of the impact damper will be reduced. As a result, the service lifetime of the stopper magnet up to the point in time when wear of the stop and/or the impact damper and/or the armature necessitates replacement is extended considerably. The axial yieldability of the housing may be increased by providing lateral beams at the outer sides of both end parts with the tensioning elements engaging in the outwardly protruding ends of the lateral beam. The tensioning elements which are located relatively far away from the central axis of the stopper magnet then yield due to their elastic nature, and also the respective end part yields in the vicinity of the central axis when an impact is taken up. Expediently, the end parts are cover caps with integrated skirts and are put on the ends of the tube section such that the skirts wrap around the ends of the tube section. The cover caps are rigid in their peripheral region while they may be somewhat yieldable in the central region. Expediently, the lateral beams are incorporated into the cover caps. It is preferred to provide one lateral beam for each cover cap. Alternatively, a star-shaped beam structure could be used instead, e.g. for the provision of three regularly distributed tensioning elements or more. In order to increase the rigidity of each cover cap in the peripheral region, a stiffening flange may be provided integral with the skirt and in the region of the respective intruding end of the lateral beam. The tensioning elements engage reliably into the ends of the lateral beams when supports are provided between the stiffening flanges and the protruding ends of the lateral beam. One of the cover caps may be designed with a circumferential continuous stiffening flange containing farther supports for fixing the stopper magnet at the operation site. The respective stop may be formed at a disk body, preferably at a boss of the disk body. The disk body is placed between a respective end of the tube section and one end part such that the disk body transmits at least a part of the impact energy into the end part, and such that impact energy is dissipated by elastic deformation of at least parts of several interacting components. In order to relieve the respective stop by dissipating the impact energy by several elastically deforming components, it is advantageous to let the disk body abut the end parts in a peripheral region only and to provide an axial clearance between a central region of the disk body and the end part. When the impact occurs, the axial clearance allows the disk body to locally yield in order to protect the stop, the impact damper and/or the armature against excessive wear. This structure allows to maintain the peripheral region of the cover cap and the peripheral region of the disk body in intimate pre-loaded contact with the end of the tube section, to provide sufficient rigidity of the housing there, while the central region of the disk body and even the central region of the end part are allowed to somewhat yield under the rifluence of the impact energy. The split design of the housing, and in some cases the yieldable arrangement of the disk body central region, are of advantage for a stopper magnet in which the stopper pin is cSiven by magnetic force in one direction only and is returned by a spring, or for a stopper magnet in which the stopper pin is driven in both axial directions by a respective one of two magnetic coils. Each of the two axial positions of the armature is defined by a respective stop. Each stop is allowed to yield axially under the impact energy. Even in the case of a stopper pin which is driven in both axial directions by respective magnetic coils light spring load may be expedient to place the stopper pin in a predetermined position when the magnetic coils are de-energised. In a preferred embodiment one end part is formed with a dome containing the weak spring biasing the armature and the stopper pin towards a defined position. The stopper pin has to co-act with the storage body of the yam feeding device. For that reason one end part of the stopper magnet is formed with a passage through which the stopper pin extends towards the storage body. The stopper pin is connected to the armature or even is unitarily formed with the armature. A stopper pin plain bearing bushing expediently is positioned between the disk body and the respective end part The bushing prevents that the stopper pin and/or the armature become stuck during the stroke movements. Expediently, between the respective disk body and the adjacent end part a thin plastic. material plate may be placed which brings about a further degree of axial elasticity to the benefit of the service lifetime of the stop, the impact damper and/or the armature itself. Manufacturing and assembling the stopper magnet are facilitated when the tube section with the coil or both coils and in some cases coil covering plates commonly are a prefabricated sub-unit of the stopper magnet The magnetic coils may either be glued or potted in the tube section. An embodiment of the invention will be described with the help of the drawings. In the drawings is: Fig, 1 a front view, partially in an axial section, of a part of a yarn feeding device, Fig. 2 a perspective view of the stopper magnet as employed in Fig. 1, and Fig. 3 a perspective explosive view of the components of the stopper magnet prior to assembly. Fig. 1 illustrates a part of a yarn feeding device F for a jet weaving machine. The yarn feeding device F includes a stopping device S, a housing 1 of which is mounted to a not shown housing of the yam feeding device. The not shown housing of the yarn feeding device, furthermore, supports a stationary storage body B, the outer diameter of which, e.g., is variable. The storage body B (one segment of the storage body B is shown only) has an opening 1 in the region where a stopper pin P engages. The stopper pin P is shown in its extended position and is part of a stopper magnet M contained in the housing 1. The stopper magnet M has a metallic housing H consisting of a tube section 2 defining an outer wall, and two end parts 3 and 4 defining upper and lower cover walls of the housing H. The end part 3 has the shape of a cover cap and is put over the upper end of the tube section 2. The lower end part 4 also has the shape of a cover cap and is put over the lower end of the tube section 2. The housing H contains two magnetic coils C1 and C2 for driving the stopper pin P via an armature A between the shown extended position and a not shown retracted position. The housing H contains two stops 7, 8 defining both positions of the stopper pin P. Between the armature A and each stop 7, 8 an annular impact damper 5, 6, preferably a washer made of plastic material, is provided. Between each end part 3, 4 and one coil C1, C2 a disk body 9,10 is placed which rests with its periphery on the respective end of the tube section 2 and which has a central boss defining the respective stop 7, 8. In the embodiment shown, between each disk body 9,10 and the end part 3, 4 a thin plate 21, e.g. made from plastic material, is placed. Both end parts 3, 4 are interconnected, in the shown embodiment, by two diametrically opposed tensioning elements T1,T2 such that the peripheral regions of the end parts 3, 4 are pressed via the plates 21, if provided, and the disk bodies 9,10 on the ends of the tube section 2. It is to be noted that only the peripheral regions of the end parts 3, 4 abut on the plates 21, if provided, and on the peripheral region of the disk bodies 9, 10. Between the central regions of the disk bodies 9,10 (and of the plates 21) and the end parts 3,4 axial clearances are provided. A stopper pin plain bearing bushing 11, e.g. made from plastic material, is positioned between the boss of the disk body 10 and the end part 4. The bushing 11 serves to axially guide the stopper pin P and via the stopper pin P also the armature A. The end part 4 has a central passage 28 for the stopper pin P. Fig. 2 illustrates in more detail how both end parts 3, 4 are interconnected by the tensioning elements T1, T2. At the outer top side of each end part 3,4 a lateral beam Q is provided, in the shown embodiment even incorporated into the end part 3, 4. In a not shown alternative, a separate lateral beam Q only could rest on the top surface of the respective end parts 3,4 instead. Each lateral beam Q protrudes with both ends beyond the periphery of the end part 3,4, The tensioning elements T1, T2 are positioned outside even with a radial distance of the tube section 2 and extend essentially parallel to the central axis of the stopper magnet M. The tensioning elements T1, T2 may be tensioning screws the heads of which are supported in the ends of the lateral beam Q of the lower end part 4 while the threaded shafts are threaded into the ends of the lateral beam Q of the upper end part 3. Fig. 3 illustrates that each end part 3 is formed like a cover cap having a circumferential skirt 15 and the integrated lateral beam Q. In a not shown alternative embodiment a star-like beam structure with three or more regularly distributed beams could be provided instead allowing to use three or more tensioning elements. The end part 3 has stiffening flanges 16 in the regions where the ends of the lateral beam Q protrude beyond the periphery. In these regions, furthermore, integrally formed supports 17 are provided, e.g. with threaded bores 18 for the threaded shaft of the tensioning screws T1, T2. A round cut-out 19 in the skirt 15 allows to place cabling 23. A shaft 14 formed in the top side of the end part 3 allows to insert other cabling and/or a sensor. The spring 12 is inserted together with a supporting disk 20 into the dome 13 of the end part 3. A tube section component group may be a prefabricated sub-unit E of the stopper magnet M. For that purpose the magnetic coils C1, C2 (not shown in Fig. 3) are glued or potted into the tube section 2, e.g. together with coil covering plates 24. The glue or potting is indicated at 25. In the prefabricated unit E the cabling 23 is already provided as well. During the assembly of the stopper magnet M of Fig. 2 a guiding sleeve 22 (Fig. 3) first is inserted into a central bore of the sub-unit E. The guiding sleeve 22 serves to guide the armature A which is inserted thereafter. Then the impact damper 5 is threaded onto the upper stem of the armature A, before the disk body 9 and, if provided, the plate 21 is put on. Next the spring 12 is threaded onto the armature A before the supporting disk 20 is put on. Finally, the end part 3 is put on the sub-unit E. The component group as described above then is turned by 180°. Next the other impact damper 6 is threaded on the stopper pin P, before subsequently the other disk body 10 and, if provided, the plate 21 is put on. Then, or even before, the bushing 11 is inserted into the boss of the disk body 10. Finally, the lower end part 4 is put on, before the tensioning elements T1, T2 are inserted into the supports 17 of the end part 4 and then are threaded into the threaded bores 18 of the end part 3. A washer 27, finally, may be placed on the end part 4. The end part 4 is formed with a circumferential continuous, square stiffening flange 16' Between the stiffening flange 16' and the ends of the lateral beam Q supports 17 for the heads of the tensioning elements T1, T2 are formed. Further supports 26 also are provided in the stiffening flange 16' and serve for the fixation of the stopper magnet e.g. in the housing 1 of Fig. 1. CLAIMS 1. Stopper magnet (M) for yam feeding devices, including a central armature (A) which is adjustable by means of at least one electromagnetic coil (C1, C2) axially from a first position into a second position against a stop (7, 8), and a metallic housing (H) containing the magnetic coil (C1, C2), the armature (A) and the stop (7, 8), the housing comprising an outer wall and upper and lower cover walls, characterised in that the housing (H) comprises a tube section (2) forming the outer wall and two separate end parts (3,4) forming the cover walls and contacting the ends of the tube section (2), and that the end parts (3, 4) are interconnected by at least two tensioning elements (T1, T2) which are located outside of the tube section (2). 2. Stopper magnet as in claim 1, characterised in that a lateral beam (Q) is provided at the outer side of each end part (3,4), the lateral beam (Q) protruding with both ends outwardly beyond the end part (3,4), that two diametrically opposed tensioning elements (T1, T2) are provided, and that the tensioning elements (T1, T2) engage into the ends of the lateral beams (Q). 3. Stopper magnet as in claim 1, characterised in that the end parts (3, 4) are unitary cover caps having circumferential skirts (15), and that the cover caps are put over the ends of the tube section (2). 4. Stopper magnet as in claims 2 and 3, characterised in that the lateral beams (Q) are incorporated into the caps. 5. Stopper magnet as in claims 2, 3, 4, characterised in that at least in the region of each protruding end of the lateral beam (Q) a stiffening flange (16,16') is provided at the skirt (15), and that between the stiffening flange (16,16') and the protruding end of the lateral beam (Q) a support (17) for a tensioning element (T11 T2) is formed. 6. Stopper magnet as in claim 5, characterised In that at least one cover cap has a circumferential stiffening flange (16') into which further supports (26) for fixing tiie stopper magnet (M) are formed. 7. Stopper magnet as in claim 1, characterised in that a disk body (9,10) is placed between the end of the tube section (2) and at least one end part (3, 4), and that the stop (7, 8) is provided at the disk body (9,10), preferably at a boss of the disk body (9,10). 8. Stopper magnet as in claim 7, characterised in that the disk body (9,10) abuts at the end part (3,4) in a peripheral region, preferably via an interposed plastic plate (21), and that in a central region of the disk body (9,10) an axial clearance is provided between the end part (3, 4) and the disk body (9, 10). 9. Stopper magnet as in claim 1, characterised in that two magnetic coils (C1, C2) each for a respective adjustment direction of the armature (A) are provided in the housing (H), that the armature (A) is driven electromagnetically in both axial directions, and that both stops (7, 8) are provided at disk bodies (9,10) which are placed between one tube section end and one end part (3, 4), respectively. 10. Stopper magnet as in claim 1, characterised in that one end part (3) is provided with a dome (13) which contains a spring (12) biasing the armature (A) in one axial direction. 11. Stopper magnet as in claim 1, characterised in that one end part (4) has a passage (28) for a stopper pin (P) which is connected to the armature (A), and that a stopper pin plain bearing bushing (11) is positioned between the disk body (10) and the end part (4). 12. Stopper magnet as in claim 1, characterised in that the at least one magnetic coil (C1, C2) is glued or potted into the tube section (2), in some cases together with a coil covering plate (24)t for forming a prefabricated sub-unit (E) of the

Documents:

4022-CHENP-2006 CORRESPONDENCE OTHERS.pdf

4022-CHENP-2006 CORRESPONDENCE PO.pdf

4022-CHENP-2006 FORM-3.pdf

4022-chenp-2006 abstract granted.pdf

4022-chenp-2006 claims granted.pdf

4022-chenp-2006 description (complete) granted.pdf

4022-chenp-2006 drawings granted.pdf

4022-chenp-2006-abstract.pdf

4022-chenp-2006-claims.pdf

4022-chenp-2006-correspondnece-others.pdf

4022-chenp-2006-description(complete).pdf

4022-chenp-2006-drawings.pdf

4022-chenp-2006-form 1.pdf

4022-chenp-2006-form 18.pdf

4022-chenp-2006-form 3.pdf

4022-chenp-2006-form 5.pdf

4022-chenp-2006-pct.pdf