The present invention relates to a jacquard mechanism.

In our UK patent 2047755 we describe a jacquard mechanism in which heald knives are individually suspended from a pair of lifting arms located at opposite ends of the knives.

The present invention is particularly concerned with a modification of jacquard mechanisms of the type described in UK patent 2047755.

According to one aspect of the present invention there is provided a jacquard mechanism for a weaving loom, the jacquard mechanism including a group of heald knives arranged side by side in a row and supported at opposite ends by a pair of knife support arms extending longitudinally along the row, each knife support arm being movably connected to a reciprocal drive means for moving the support arm between upper shed and lower shed positions, the reciprocal drive for each knife support arm including an articulated lever system pivotally connected to the knife support arm at two locations spaced apart longitudinally of the support arm, each lever system including a first lever directly pivotally connected to a static frame of the jacquard mechanism by a first pivot connection and directly pivotally connected to the knife support arm at one of said locations by a second pivotal connection, the lever system further including an articulated lever assembly comprising a plurality of pivotally inter-connected levers which provide an articulated connection between the support arm at the other of said locations and the first lever at a position spaced from the second pivotal connection, the lever assembly being mounted on the static frame, the arrangement of the first lever and lever assembly being such that the articulated lever system supports the knife

support arm and guides movement of the knife support arm during movement between the upper and lower shed positions.

Various aspects of the present invention are hereinafter described, with reference to the accompanying drawings, in which :-

Figure 1 is a side view showing part of a jacquard mechanism according to one embodiment of the present invention;

Figure 2 is a diagrammatic view of the embodiment shown in Figure 1 at a bottom shed position; Figure 3 is a similar view to Figure 2 showing the embodiment of

Figure 1 at a top shed position;

Figure 4 is a diagrammatic view similar to Figure 2 showing an alternative embodiment of the invention;

Figure 5 is a more detailed perspective view of a further embodiment according to the invention;

Figure 6 is a side view, partly broken away, of the embodiment shown in Figure 5.

In Figure 1 there is shown a heald knife support arm 10 which is connected to a drive mechanism 20 at a pair of connection locations 8, 9 spaced apart in the longitudinal direction of the support arm 10.

A group of heald knives 15 (some of which are omitted for clarity) are arranged side by side in a row and are connected at one end to the support arm 10. As seen, the row of knives extend in the longitudinal direction of the support arm 10. Although not shown the opposite ends of the heald knives are connected to a second support arm 10 and an identical drive mechanism to that shown in Figure 1.

Each knife 15 is connected to the respective arm 10 by a link 16 which is

pivotally attached to the arm 10 in a similar manner to that described in UK patent 2047755.

The drive mechanism 20 acts to raise and lower the support arm 10 between upper and lower shed positions in a continuous reciprocal manner during operation of the jacquard mechanism.

The drive mechanism 20 includes an articulated lever system 25 which acts to support the knife support arm 10 and the knives 15 connected thereto and also acts to guide movement of the support arm 10 during movement between upper and lower shed positions and thereby define the upper and lower shed positions of the knives.

The articulated lever system 25 includes a first lever 26 which is directly pivotally connected to a static frame member 28 of the jacquard mechanism by a first pivotal connection 29 and is directly pivotally connected to the knife support arm 10 at connection location 9 by a second pivotal connection 30.

Accordingly, lever 26 is constrained to move in an arc about the pivot defined by the first pivotal connection 29 and so causes the second pivotal connection 30 to move along an arcuate path of travel.

Since arm 10 is constrained to move in an arc about pivotal connection 30 lateral displacement of the arm 10 relative to frame 28 is also positively guided during reciprocal movement of the lever 26 about pivotal connection 29.

The drive mechanism 20 further includes an articulated lever assembly 40 which acts to provide an articulated connection between the first lever 26

and the support arm 10 so as to control relative displacement between the first lever 26 and arm 10 about pivotal connection 30. The articulated connection is defined by a pair of levers 42, 43 which are pivotally connected by a pivotal connection 50. Lever 42 is pivotally connected to the first lever 26 by a pivotal connection 45 which is located at a greater distance along lever 26 from pivotal connection 29 than pivotal connection 30. Lever 43 is pivotally connected to support arm 10 at location 8 by a pivotal connection 47.

Lever 42 has an extension portion 42a which is mounted on frame 28 so as to provide support for the lever 42 whilst permitting pivotal and lateral displacement of the lever 42 relative to the frame 28. Preferably lever extension portion 42a is connected to the frame 28 by a lever 41 which is pivotally connected at one end to lever extension portion 42a by a pivotal connection 49 and is pivotally connected at its other end by a pivotal connection 51.

The lever 41 is provided to enable the lever 42 to move longitudinally along its length (ie laterally relative to the frame) in order to accommodate for the lateral displacement of the pivotal connection 45 as it moves along its arcuate path during reciprocation of lever 26.

It is envisaged that other forms of mechanical linkage may be provided in order to achieve the same mechanical effect. For example, it is envisaged that other forms of mounting extension portion 42a to frame 28 may be provided, for example a roller and slide guide assembly may be used instead of lever 41. In this respect, a roller may be provided on the extension portion 42a at the location of pivotal connection 49, the roller being located in a guide mounted on the frame 28 and extending in the longitudinal direction of lever 42.

Alternatively, as schematically illustrated in Figure 4 lever extension 42a may be directly pivotally connected to the frame 28 and lever 42 be articulated to lever 26 by an intermediate lever 46.

A further alternative envisaged is to directly pivotally connect lever extension 42a to the frame 28 and to adapt the lever extension 42a such that its effective length is variable during reciprocation of the lever 26, eg. the lever extension 42a may be telescopically constructed.

Each lever system 25 is raised and lowered between upper and lower shed positions by a push rod 60 which is mounted on an eccentric 61 and pivotally connected to lever 26 by pivotal connection 62. The eccentric 61 is mounted on a continuously rotating drive shaft (not shown) and acts to reciprocally raise and lower lever 26 about pivotal connection 29.

Such movement raised arm 10 at location 9 and causes the pivotal connection 30 to travel along an arcuate path (see Figures 2 and 3). Pivotal connection 45 likewise is caused to move along an arcuate path but by a greater distance due to it being spaced further from pivotal connection 29.

Accordingly, since lever 42 is constrained to move along an arcuate path about pivotal connection 49, the levers 42, 43 move relatively apart (see Figure 3) and so cause the arm 10 to move about pivotal connection 30 relative to lever 26.

The amount of relative displacement of the arm 10 is therefore positively controlled by the articulated connection between pivotal connections 47 and 45. The relative distances between pivotal connections 30 and 45; 45 and 50; 50 and 47; and 47 and 30 determine the amount of relative

displacement and this is preferably chosen such that the orientation of the support arm 10 at its lower shed position is different to its orientation at its upper shed position (this is shown schematically in Figures 2 and 3 respectively).

In the illustrated embodiment, pivotal connections 47 and 50 are adjustable for varying the distances between pivotal connections 50 and 45; and 47 and 30 respectively for providing adjustment for the amount of displacement about pivotal connection 30 and thereby providing adjustment of the relative orientation of the arm at lower and upper shed positions. It is also envisaged that only one of pivotal connections 47 or 50 may be adjustable. It will be appreciated that as an alternative or as an addition, pivotal connections 45 and/or 30 may be adapted for adjusting their position.

In addition, the relative lengths of levers 26, 42 also determine the amount of relative displacement affecting the orientation of the arm 10 at its top and bottom shed positions. Preferably the lever 26 is chosen to be longer than lever 42.

A more detailed perspective side view of a jacquard mechanism 100 is illustrated in Figure 5, wherein parts similar to those described in relation to Figure 1 are identified by the same reference numerals.

In mechanism 100, two groups of heald knives, 15a, 15b are provided each of which is supported and reciprocally driven by respective drive mechanisms 20a, 20b. The drive mechanisms 20a, 20b oscillate the respective groups of heald knives 180° out of phase.

For each mechanism 20a, 20b, the levers 26 and levers 42 comprise a pair

of side by side arms 26a, 26b and 42c, 42d, respectively; the arms of each pair being spaced apart so as to locate the remaining levers of the lever system therebetween.

Preferably, the lever 26 is made as long as possible to provide minimum lateral displacement of the support arm 10 during reciprocation of the lever 26. In this respect, the lever 26 is preferably connected to the arm 10 at location 9 (as opposed to location 8) in order to further reduce lateral displacement of the arm 10 as connection 30 travels along its arcuate path.