Improved device for driving the ring levers controlling the keys of a high-speed rotary dobby

Abstract: A device for driving the ring levers (1) controlling the keys (2) of a high-speed rotary dobby, in which a metal rocker armature (14) is hinged to each lever along that axis of symmetry of the device which passes through the fulcrum (7) about which said levers rock, and has at its lower ends teeth (15,16) which cooperate with corresponding grooves (17,18) in two dragging tracks moving with reciprocating movement perpendicular to said axis of symmetry and in mutual opposition, the upper surface of said armature cooperating with one of two overlying electromagnets (28,29) arranged symmetrical about said axis of symmetry. Constructional details are also provided.

Description: This invention relates to a device for driving the ring levers controlling the keys of a high-speed rotary dobby which, by using rocker arms pivoted on said ring levers symmetrically about an axis of symmetry passing through the fulcrum of said levers and made suitably rigid by pairs of electromagnetic systems with one of two dragging grooves rocking in mutual opposition symmetrically about said axis of symmetry, results in considerable compactness, efficiency and constructional simplicity, allows the operating speed to be increased, and enables the dobby to be halted and put into reverse running at any moment, as all idle times are eliminated. As already known from our previous European Patent Appln. public. No. O 466 234 of January 1, 1992, which falls under Article 54 (3) EPC, the device for driving the ring levers controlling the keys of a high-speed rotary dobby comprises, for each lever, a V-shaped spring which has the ends of its two arms inserted into a cavity of said lever facing the lever fulcrum, said spring being mounted preloaded between two fixed shoulders positioned symmetrically about the axis of symmetry of said spring, which passes through said fulcrum of the controlling ring lever, this lever also comprising a second cavity opposite the preceding and cooperating with a slide to which there is hinged the lower end of a sector which rocks symmetrically about said axis of symmetry, said sector comprising in its upper part two valleys arranged symmetrically about said axis of symmetry and cooperating with the lower end of an overlying pusher rod which, hinged at its upper end to an arm projecting from a single dobby shaft made to rock by a control mechanism preferably of cam type synchronized with the dobby modulation mechanism, is slidingly inserted between two pins of a needle selector which cooperates with the port of a programmer by the action of a thrust spring and a return extractor comb made to rock by a second control mechanism preferably of cam type and also synchronized with said modulation mechanism. Such a known device, besides being of evident constructional complexity, has the drawback of a loss of operational effectiveness and reliability with time because of the presence of said V-shaped spring, and in particular presents idle times during which the dobby cannot be put into reverse running and which considerably limit its operational speed. In this respect, in said known device the programmer provides the enabling command to the selector needle, which can then move to cause the forcing member (pusher rod) to operate and transmit the desired movement to the controlling ring lever via the rocking sector; the needle and the rocking sector must then be returned to their rest position with the aid respectively of a further control mechanism and said V-shaped spring to be able to recommence the entire cycle from the beginning, hence the entire time required for these operations which decide whether the ring lever is to be moved represents time lost to the dobby. The document EP-A-68 139 shows another device for driving the ring levers controlling the keys which corresponds to the first part of independent claim 1. In this device, the presence of return springs also means that the operational speed is limited. The object of the present invention is to obviate said drawback by providing a device for driving the ring levers controlling the keys in a rotary dobby which combines considerable compactness and constructional simplicity with lasting operational effectiveness and reliability at the highest speeds and with a more immediate intervention capacity, and, according to a further preferred characteristic, suffers from no condition under which the dobby cannot be put into reverse running. This is substantially attained in that the device is always returned into its rest position not by springs but instead, in a completely positive manner, by the actual operating system itself which is preferably in the form of a parallelogram which, hinged at one end on the same axis as that on which the ring levers are pivoted, is alternately opened and closed, symmetrically about the device axis of symmetry passing through the fulcrum about which said ring levers rock, by the control mechanism of cam type acting on the other end. The movement of the individual levers towards one or the other side about said axis of symmetry of the device is achieved in a simple manner by a metal rocker armature which is hinged to said lever in a position corresponding with said axis of symmetry but perpendicular to this latter, and inserts one of two engagement teeth provided at its downwardly facing ends into the grooves of one of two dragging tracks or crosspieces perpendicularly rigid respectively with two sides of said preferential parallelogram operating system which consequently moves them with reciprocating motion in mutual opposition and perpendicular to said axis of symmetry, said insertion being controlled by two double-winding electromagnets which, energized by the dobby programmer and arranged symmetrically about said axis of symmetry, attract the upper surface of one and the other end of said rocker armature. From the aforegoing it is apparent that the device is of great simplicity, is reliable in operation and is of instant intervention given that the energization of an electromagnet results in the immediate attraction of the corresponding underlying side of the armature so that the other side of the armature is obliged to insert its teeth into the underlying groove in the corresponding dragging track or crosspiece, which hence moves the armature and consequently the control ring lever itself; again, by creating a wider zone of magnetic influence, the double-winding of said electromagnets ensures that the rocker armature always remains under the magnetic influence during its entire travel. Hence, the device for driving the ring levers controlling the keys of a high-speed rotary dobby, having an axis of symmetry passing through the fulcrum about which said ring levers rock and comprising a cam control mechanism and a programmer, is characterised according to the present invention in that for each ring lever there is positioned along said axis of symmetry a support hinged lowerly on said fulcrum about which said ring levers rock and made rigid with the relative ring lever, to support hinged to its upper end a metal rocker armature positioned perpendicular to said axis of symmetry and provided at its downwardly facing ends with two engagement teeth arranged to cooperate with corresponding grooves of two dragging tracks or crosspieces arranged parallel to the hinging axis of said armature and moved with reciprocating movement, perpendicular to said axis of symmetry and in mutual opposition, by an operating system controlled by said cam control mechanism, said rocker armature cooperating via its upper surface with one of two double-winding electromagnets arranged symmetrically about said axis of symmetry and controlled by said programmer. According to a preferred embodiment of the present invention, said operating system for said dragging tracks or crosspieces is a parallelogram system of which the two lower sides, to which said dragging tracks or crosspieces are rigidly connected, are hinged on the same pivotal axis as the ring levers, while the two upper sides are hinged to the end of an arm projecting from a shaft rockingly driven by said cam control mechanism. Again, in order to compensate the phase displacement between the position of the key and the position of the relative radial locking grooves during the reverse running of the dobby and during the movement of the key, according to a further preferred charateristic of the present invention said support for said rocker armature provided along said axis of symmetry is made rigid with the relative ring lever by a spring preloaded between two shoulder or abutment blocks inserted into the ends of corresponding slots in the support and in the ring lever. Given that for the intrinsic operation of the device the metal rocker armature is always attracted either by one or by the other double-winding electromagnet and has to move dragged by that one of the two said dragging tracks or crosspieces, rocking in mutual opposition, into the groove of which it has inserted its engagement tooth, then in order to prevent deleterious rubbing between the ends of the pole shoes of said electromagnets and the upper surface of said armature, according to a further preferred characteristic of the present invention any contact between said elements is prevented and an extremely small and constant gap is maintained therebetween throughout the entire arc of movement by suitably shaping and dimensioning the rocking system, the electromagnets and the rocking stroke. More specifically, said double-winding electromagnets are formed with pole shoes dimensioned such that the edges of their ends lie on a single circumference with its centre on said fulcrum about which the ring levers rock, the upper surface of the metal rocker armature being shaped as a cusp consisting of two circular arcs symmetrical about said axis of symmetry and such that each has its centre on said fulcrum about which the ring levers rock when in the position which it assumes after attraction by the relative electromagnet, said grooves in the dragging tracks or crosspieces being of such a depth that when a tooth of the armature is engaged in said groove, the circular arc of the armature attracted by the electromagnet forms a constant air gap with said electromagnet. Finally, to prevent any possibility of withdrawal of the tooth engaged by the relative groove of the dragging tracks or crosspieces which move with reciprocating motion in mutual opposition, according to a further preferred characteristic of the present invention said rocker armature is hinged on said support in such a manner that the normal to the surfaces of contact between the engaging tooth of the armature and the groove of the relative track into which the tooth is inserted, said normal passing through the centre of said surfaces, intersects the centre of hinging of said rocker armature. In this manner, no couples are generated which tend to extract the teeth. The invention is further clarified hereinafter with reference to the accompanying drawings which illustrate a preferred embodiment thereof given by way of non-limiting example. In said drawings: Figure 1 is a partly sectional partial view of a device for driving the ring levers controlling the keys of a high-speed rotary dobby in accordance with the invention; Figure 2 is a partial front sectional view to an enlarged scale of the device of Figure 1; Figures 3 and 4 are front sectional views to a very enlarged scale showing details of the device of Figure 2 which illustrate characteristics of the invention. In the figures, the reference numeral 1 indicates one of the ring levers controlling the key 2 of the rotary dobby, and 3 and 4 indicate the dobby cam control mechanism and programmer respectively. Said ring lever 1 comprises, along the axis of symmetry 5, a support 6 which is hinged lowerly on the fulcrum 7 about which the dobby ring levers rock and is made rigid with said ring lever 1 by a spring 8 preloaded between two shoulder or abutment blocks 9 and 10 respectively, inserted into the ends of corresponding slots 11 and 12 of the support 6 and ring lever 1 respectively. Said support 6 comprises, hinged to its upper end by the pin 13, a metal rocker armature 14 arranged perpendicular to said axis of symmetry 5 and comprising at its downwardly facing ends two engagement teeth 15 and 16 arranged to cooperate with corresponding grooves 17 and 18 in two dragging tracks or crosspieces 19 and 20 arranged parallel to the axis of the pin 13 and moved with reciprocating movement perpendicular to the axis of symmetry 5 and in mutual opposition, by a parallelogram-type operating system 21 consisting of two lower sides 22 and 23, to which said tracks 19 and 20 are perpendicularly fixed and which are hinged on said fulcrum 7 about which the ring levers 1 rock, and two upper sides 24 and 25 respectively, having one end hinged to the corresponding lower sides 22 and 23 and their other ends hinged together and to an arm 26 projecting from a shaft 27 made to rock by said cam control mechanism 3. Said rocker armature 14 cooperates via its upper surfaces 14' and 14'' with one of two double-winding electromagnets 28 and 29 arranged symmetrically about said axis of symmetry 5, and controlled by said programmer 4. The rocker armature 14 is hinged on said support 6 by the pin 13 such that the normal 30 (see specifically Figure 4) passing through the centre of the contacting surfaces, namely the surface 31 of the engaging tooth 16 of the armature 14 and the surface 32 of the groove 18 of the relative track 20, intersects the centre of the pin 13. Again, said electromagnets 28 and 29 have their pole shoes 33 dimensioned such that the edges 34 of their ends lie on a single circumference 35 (see specifically Figure 3) having its centre on said fulcrum 7 about which the ring levers 1 rock, and the upper surfaces 14' and 14'' of the metal armature 14 are shaped as a cusp formed from two circular arcs 36 and 37 respectively, which are symmetrical about said axis of symmetry 5 and such that each has its centre on said fulcrum 7 about which the ring levers 1 rock when in the position it assumes after attraction by the relative electromagnet, as represented in Figure 3 by the circle 36, which is consequently concentric with said circumference 35 and spaced therefrom by a gap 38 which is maintained constant during the entire travel of the armature 14 rigid with the dragging track 20 (see Figure 4), said gap 38 being determined by an appropriate depth of the grooves 17 and 18 which limit the downward movement of the engagement teeth 15 and 16 of the metal armature 14 and hence the rocking of said armature. Finally, as is clearly visible in Figure 4, the use of double-winding electromagnets ensures that the rocker armature 14 remains always under magnetic influence during its entire travel.

Claims: A device for driving the ring levers (1) controlling the keys (2) of a high-speed rotary dobby, having an axis of symmetry (5) passing through the fulcrum (7) about which said ring levers (1) rock and comprising a cam control mechanism (3) and a programmer (4), characterised in that for each ring lever (1) there is positioned along said axis of symmetry (5) a support (6) hinged lowerly on said fulcrum (7) about which said ring levers (1) rock and made rigid with the relative ring lever (1), to support hinged to its upper end a metal rocker armature (14) positioned perpendicular to said axis of symmetry (5) and provided at its downwardly facing ends with two engagement teeth (15,16) arranged to cooperate with corresponding grooves (17,18) of two dragging tracks or crosspieces (19,20) arranged parallel to the hinging axis of said armature and moved with reciprocating movement, perpendicular to said axis of symmetry (5) and in mutual opposition, by an operating system (21) controlled by said cam control mechanism (3), said rocker armature (14) cooperating via its upper surface (14',14'') with one of two double-winding electromagnets (28,29) arranged symmetrically about said axis of symmetry (5) and controlled by said programmer (3). A drive device as claimed in claim 1, characterised in that said operating system (21) for said dragging tracks or crosspieces (19,20) is a parallelogram system of which the two lower sides (22,23), to which said dragging tracks or crosspieces (19,20) are rigidly connected, are hinged on the same pivotal axis as the ring levers (1), while the two upper sides (24,25) are hinged to the end of an arm (26) projecting from a shaft (27) rockingly driven by said cam control mechanism (3). A drive device as claimed in claim 1, characterised in that said support (6) for said rocker armature (14) provided along said axis of symmetry (5) is made rigid with the relative ring lever (1) by a spring (8) preloaded between two shoulder or abutment blocks (9,10) inserted into the ends of corresponding slots (11,12) in the support (6) and in the ring lever (1). A drive device as claimed in claim 1, characterised in that said double-winding electromagenets (28,29) are formed with pole shoes (33) dimensioned such that the edges (34) of their ends lie on a single circumference (35) with its centre on said fulcrum (7) about which the ring levers (1) rock, the upper surface (14',14'') of the metal rocker armchair (14) being shaped as a cusp consisting of two circular arcs (36,37) symmetrical about said axis of symmetry (5) and such that each has its centre on said fulcrum (7) about which the ring levers (1) rock, when in the position which it assumes after attraction by the relative electromagnet, said grooves (17,18) in the dragging tracks or crosspieces (19,20) being of such a depth that when a tooth (15,16) of the armature is engaged in said groove, (17,18) the circular arc (36,37) of the armature (14) attracted by the electromagnet (28,29) forms a constant air gap (38) with said electromagnet. A drive device as claimed in claim 1, characterised in that said rocker armature (14) is hinged on said support (6) in such a manner that the normal (30) to the surfaces (31,32) of contact between the engaging tooth (15,16) of the armature and the groove (17,18) of the relative track (19,20) into which the tooth is inserted, said normal (30) passing through the centre of said surfaces (31,32), intersects the centre of hinging of said rocker armature (14).

Inventors: VINCIGUERRA COSTANTINO, VINCIGUERRA, COSTANTINO
Applicants: NUOVO PIGNONE SPA, NUOVOPIGNONE INDUSTRIE MECCANICHE E FONDERIA S.P.A.
Application year: 1992
Main classification: D03C1
IPC codes: D03C13, D03C1, D03C5