Jacquard selection system
This invention relates to a jacquard selection system. More particularly, this invention relates to a jacquard selection system for a weaving machine. 
     As is known, jacquard selection systems have been known for selecting warp yarns of a weaving machine which are to be moved into a top-shed position and a bottom-shed position. Generally, these selection systems are controlled in accordance with a weave program and comprise multimorphous bending elements and jacquard needles which sense the bending elements. The needles, in turn, cooperate with lifting wires to move the warp yarns. The term &#34;multimorphous bending elements&#34; is intended to denote electro- or magnetostriction elements which are usually in rod form and which are usually made of a ceramic substance, such as lead-zirconate-titanate and which, when acted upon by an external electric or magnetic field, undergo deformations, more particularly bending, transversely of their length. 
     In conventional systems of this kind, for example as described in Swiss Patent Specification No. 553,860, the bending element is sensed directly by the associated jacquard needle. In other known constructions, for example as described in Swiss Patent Specification No. 552,691, the bending element has a strengthening cap or a blocking spring which the jacquard needle abuts during sensing. 
     The known constructions, however, have various disadvantages. In the first case, the bending element experiences relatively heavy stressing when sensed by the jacquard needle and tends to break because of the brittleness of the material from which the element is made. In the second case, the bending element has to preform a relatively considerable amount of work to oppose the friction between the spring and the casing of the bending element. Such a spring cannot withstand adequate sensing pressures from the jacquard needle since the spring must be very thin in order to be of reduced weight. 
     Accordingly, it is an object of the invention to provide a jacquard selection system which does not subject a multimorphous bending element to heavy stressing. 
     It is another object of the invention to provide a jacquard selection system which is exposed to a minimum of friction during usage. 
     It is another object of the invention to provide a jacquard selection system wherein individual bending elements need to perform little or no work while being deflected. 
     It is another object of the invention to avoid stressing of a bending element of a jacquard selection system by a jacquard needle. 
     Briefly, the invention provides a jacquard selection system which comprises a plurality of multimorphous bending elements, a plurality of jacquard needles each of which is disposed to sense the position of a respective bending element, a guide and a plurality of sliders. Each slider is reciprocally mounted within the guide between each bending element and a respective needle to selectively inhibit a sensing movement of the respective needle. The effect of the guided inhibiting slider is that the individual bending element needs to perform substantially no work while being deflected. The slider can be made adequately strong, so that the jacquard needles can apply adequate sensing forces thereto. The bending element itself is not stressed by the jacquard needle. 
     The selection system is such that each bending element has a free end which is movable between two positions while each jacquard needle is movably mounted for movement into one of a sensing position and a non-sensing position relative to a bending element. Each slider in the guide is mounted so as to be moved under the influence of a bending element to selectively inhibit movement of a jacquard needle into the non-sensing position. To this end, each slider is moved as the free end of a bending element moves. This may be accomplished by having a slider secured to the free end of a bending element or by having the free end of a bending element received in a slider. The inhibiting effect of each slider is such that when a needle is to &#34;sense&#34;, the slider is moved into the path of the needle to inhibit motion. At this time, the slider which has been loosely disposed within the guide is pressed against a wall of the guide so that the force imposed by the needle on the slider is transferred into the guide and not the bending element. When a needle is to be in a &#34;non-sensing&#34; position, the associated slider is moved out of the path of the needle by the bending element. 
    
    
     These and other objects and advantages of the invention will become more apparent from the following detailed description and appended claims taken in conjunction with the accompanying drawings in which: 
     FIG. 1 illustrates a sectional view of a jacquard selection system according to the invention; 
     FIG. 2 illustrates a view taken on line II--II of FIG. 1; 
     FIG. 3 illustrates a view of a jacquard selection system according to the invention having various modified components; 
     FIG. 4 illustrates a view taken on line IV--IV of FIG. 3; 
     FIG. 5 illustrates a view similar to FIG. 4 of a further modified embodiment of a jacquard selection system according to the invention; 
     FIG. 6 illustrates a view of a further modified jacquard selection system according to the invention; and 
     FIG. 7 illustrates a view taken on line VII--VII of FIG. 6. 
    
    
     Referring to FIGS. 1 and 2, a jacquard selection system for selecting warp yarns of a weaving machine (not shown) which are to be moved from a top-shed position to a bottom-shed position includes a casing 1, for example of plastics which is suitably mounted for the purpose intended. The system further includes a plurality of multimorphous bending elements 2 each of which is mounted in the casing 1 via a mounting 3 made, for example of some other plastics, such as araldite, from the casing 1. The free end of each bending element 3 carries an S-shaped spring 5 which is connected to the bending element by an extruded plastics member 6 made, for example, of araldite. 
     Each bending element 2 is connected to an electric field via an electrical supply wiring 25 so that the free ends of each may be moved between two positions. 
     The jacquard selection system further includes a plurality of sliders 7 separably mounted from the bending elements 2 and a plurality of jacquard needles 8 as well as a means (not shown) for moving the needles 8 into and out of the casing 1 as is known. As shown, each slider 7 is secured to the end of a spring 5 opposite a bending element 2 while each needle 8 extends via a passage 9 into the interior of the casing 1. The sliders 7 are reciprocally guided within a guide 12 of the casing so as to be moved relative to the passages 9 by the bending elements 2. As shown, each slider 7 is mounted with a clearance 11, shown exaggerated, within the guide 12 so as to be virtually suspended in the guide 12. 
     Each needle 8 is movable into either a sensing position or a non-sensing position while each slider 7 is movable so as to selectively inhibit a sensing movement of a respective needle 8. To this end, when a slider 7 is moved into an inhibiting or blocking position 7a, as viewed in the lower positions of FIG. 1, the sensing movements of the respective needles 8 are blocked. Thus, the needles become positioned in the sensing positions 8a. At this time, these needles 8 push the sliders 7 to the right, as viewed, against a wall 13 of the guide 12. The forces of these needles 8 are then transferred via the sliders 7 and wall 13 into the casing 1 rather than into the bending elements 2. The needles 8 can therefore apply relatively high sensing forces to the sliders 7 without the springs 5 or bending elements 2 being stressed. 
     When a slider 7 is moved into a non-blocking position, as viewed in the uppermost position of FIG. 1, the sensing movement of a needle is un-inhibited so that the needle 8 may move into the non-sensing position. 
     Referring to FIG. 1, the bending elements 2 are movable under the electric field from an inoperative position, as shown in the upper positions, into an operative position, as shown in the two lower positions. When the electric field is activated, the bending elements 2 move into the deflection positions 2a to inhibit the pressing or sensing movement of the respective needles 8. However, if no electric field acts on the electrostrictive elements 2, the elements remain in the inoperative position so that the respective needle 8 can be moved into a pressing position (i.e. a non-sensing position). 
     The movement of the needles 8 acts to engage and disengage jacquard lifting wires (not shown) in known manner with and from vertically reciprocating griffes, so that the warp yarns of an associated weaving machine can be moved into a top-shed or bottom-shed position. 
     Referring to FIG. 2, the casing 1 has a horizontal bearing ledge 14 on which the plastics members 6 can slide and reciprocate in the direction indicated by an arrow 16. Thus, the weight of the free ends 4 of the elements 2, the springs 5, members 6 and sliders 7 is carried on the ledge 14. In addition, a wall 17 is provided in the casing 1 transverse to the elements 2 and is provided with apertures 18 through which the elements 2 pass in order to limit the transverse movements of the elements 2. 
     Referring to FIGS. 3 and 4, wherein like reference members indicate like parts as above, each bending element 2 is mounted in a pair of spaced-apart mountings 3 of cylindrical shape. In addition, instead of a spring, each bending element 2 carries an extruded plastics top 22 at the free end. Each top 22 has a triangularly shaped tip 21 extending co-axially of a bending element 2. Also, each slider 7 includes a recess 23 which receives a tip 21. In this way, each slider 7 may be moved within the guide 12 under the influence of a movement of a bending element 2 from an inoperative position to an operative or inhibiting position 7a. 
     As shown in FIG. 4, each top 22 slides on a horizontal ledge 14 within the casing 1. 
     As shown in FIGS. 3 and 4, each bending element 2 is connected at an intermediate point via a pair of leads 25 to an electrical supply source (not shown). 
     Referring to FIG. 5, wherein like reference characters indicate like parts as above, the guide for the sliders 7 may be formed of a steel guide bar 31 mounted within the casing 1. 
     Referring to FIGS. 6 and 7, wherein like reference characters indicate like parts as above, the sliders may be in the form of piston-like cylinders 7c which can be moved into the blocking or inhibiting position 7d directly by the free ends 4 of the bending elements 2. In this embodiment, the guide 12c for the sliders 7c is a steel cylinder mounted in the casing 1. In addition, the mounted ends of the bending elements 2 are each clamped by a spring 32 which also supplies the voltage necessary to move the element 2.