Patent Description:
As generally known, in rapier weaving machines, a gripper is attached at the front end of a rapier for moving the gripper through a shed. The rapier is driven by a rapier wheel arranged next to the shed. The rapier can be a flexible gripper band or a more rigid gripper rod.

A rapier wheel is shown for example in <CIT>, wherein the rapier wheel has a number of spokes, which are arranged in pairs, wherein each pair of spokes comprises two crosswise arranged straight spokes.

It is the object of the invention to provide a rapier wheel having a low moment of inertia about its drive shaft that has a high rigidity and durability. It is a further object of the invention to provide a rapier weaving machine with such a rapier wheel.

These objects are solved by the rapier wheel and the rapier weaving machine with the features of claims <NUM> and <NUM>.

According to a first aspect, a rapier wheel for a rapier weaving machine is provided, the rapier wheel having an inner ring, an outer ring, and a number spokes, wherein the inner ring is configured and adapted for mounting the inner ring to a drive shaft, wherein the outer ring is provided with teeth configured and adapted for engaging with a rapier for driving the rapier, wherein the spokes extend between the inner ring and the outer ring and connect the inner ring with the outer ring, wherein the spokes are arranged crosswise in pairs of spokes comprising a first spoke and a second spoke, wherein the first spoke and the second spoke extend in opposite directions and cross each other at a crossing point between the inner ring and the outer ring, and wherein the first spoke and the second spoke are each convexly curved toward the outer ring.

In other words, in contrast to prior art <CIT>, in accordance with the invention, the first spokes and the second spokes are each convexly curved toward the outer ring.

In the context of the application, curved spokes, that extend either entirely or in portion along a path which seen in an outward radial direction of the associated pair of spokes is above a virtual straight line connecting ends of the spokes at the inner ring and the outer ring, are referred to as "convexly curved toward the outer ring". As a result of the convex curvature, the crossing point of the first spoke and the second spoke is closer to the outer ring than a crossing point of two virtual straight lines crossing each other, wherein each virtual straight line connects an end point of a spoke of a pair of spokes at the inner ring and an end point of this spoke at the outer ring.

Throughout this description and the claims, the indefinite article "a" or "an" means "one or more". Reference to "a first element" does not mandate presence of "a second element". Further, the expressions "first" and "second" are only used to distinguish elements from one another and are not to be interpreted as indicating any order.

The first spokes and the second spokes are also conjointly referred to as spokes.

Providing convexly curved spokes allows to counter tangential forces as well as radial forces exerted on the outer ring by the rapier, wherein resulting bending stresses on the spokes due to external forces can be reduced or even be avoided. Hence, in an ideal configuration, only pressure forces or tensile forces are acting on the spokes.

The rapier wheel rotates back and forth. Therefore, according to the invention, the spokes are provided in pairs, wherein the two spokes of each pair are curved in opposite directions. The spokes curved in opposite directions allow to counter forces regardless of a direction of rotation of the rapier wheel.

The first spoke for example is curved in a clockwise direction, i.e., its end point at the outer ring is angularly offset in a clockwise direction from its endpoint at the inner ring. In this case, the second spoke is curved in a counterclockwise direction, i.e., its end point at the outer ring is angularly offset in a counterclockwise direction from its end point at the inner ring. The expressions first and second in this context are only intended to distinguish the spokes from each other and not to indicate any relevance or order of the spokes. The shape of the spokes is chosen, such that the first spoke of each pair of spokes does not cross any other first spoke, and the second spoke of each pair of spokes does not cross any other second spoke.

The rapier wheel is manufactured for example by injection molding, milling, waterjet cutting or punching.

In one embodiment, each spoke has a constant radius of curvature, wherein the radius of curvature is the same for all spokes.

In other embodiments, a curvature of each of the spokes starts at a center of the rapier wheel and increases towards the outer ring. In other words, the spokes are spirally curved. In one embodiment, the curvature increases continuously towards the outer ring. The spokes extend between an outer edge of the inner ring and an inner edge of the outer ring. However, a curvature of the spokes starts at an imaginary line at the center of the rapier wheel. The expression "starts at a center" is not to be interpreted in such way that the imaginary line has its center of origin at the center of the rapier wheel. In one embodiment, the curvature is chosen such that the curvature asymptotically approaches the center of the rapier wheel.

In one embodiment, spokes that differ in shape are provided. In other embodiments, the first spokes and the second spokes have a same shape, wherein the first spoke and the second spoke of each pair of spokes are arranged symmetrically to a radial direction through the crossing point of this pair of spokes. When providing spokes having a same shape, the crossing points of all pairs of spokes are arranged on a first imaginary circle.

In one embodiment, in addition to a curvature towards the outer ring, the spokes are also curved in a direction of an axis of rotation of the rapier wheel. In another embodiment, the first spokes and the second spokes are arranged in two parallel planes, wherein in one embodiment the spokes of each pair are connected to each other at the crossing points. In particular embodiments, the rapier wheel is flat, wherein the first spokes and the second spokes are arranged in a common plane.

In embodiments, the pairs of spokes are evenly distributed about the rapier wheel. Depending on the number of spokes, the size of the rapier wheel and the size of the spokes, the first spoke of each pair of spokes does only cross the second spoke of the associated pair of spokes, or in addition crosses one or more second spokes of other pairs of spokes.

In one embodiment, the crossing points of the pairs of spokes are arranged on a first imaginary circle, wherein the first spokes and the second spokes of two immediately neighboring pairs of spokes cross at second crossing points, wherein the second crossing points are arranged on a second imaginary circle having a smaller radius than the first imaginary circle. In the context of the invention, pairs of spokes that are successively arranged along the circumference of the outer ring are referred to as immediately neighboring pairs of spokes.

In one embodiment, only the first spokes and the second spokes of immediately neighboring pairs of spokes cross each other. In this case, in one embodiment, the second imaginary circle is at a region of the inner ring, wherein connecting areas are formed between the inner ring and the first spokes and the second spokes of the two pairs of spokes.

In one embodiment each first spoke crosses the second spokes of two or more pairs of spokes. In case the first spokes cross the second spokes of more than one other pair of spokes, an imaginary circle of the crossing points decreases with the distance between the pairs of spokes at the outer ring.

In one embodiment, an imaginary circle of crossing points between the first spoke and the second spoke furthest away from the first spoke in a circumferential direction of the rapier wheel, but still crossing the first spoke, is at a region of the inner ring, wherein connecting areas are formed between the inner ring and the first spokes and the second spokes of the two associated pairs of spokes.

The connecting areas at the inner ring in particular embodiments are closed. In the context of the application, the expression "area. is closed" is used to describe that the area is filled with material. When the first spokes and the second spokes of different pairs of spokes cross each other in a region close to an outer edge of the inner ring, essentially triangular connecting areas are formed, wherein when filling the connecting area, an inner ring having a starshaped outer edge is formed.

In one embodiment, supporting rods are provided that extend between the crossing points of the pairs of spokes and the outer ring. The supporting rods extend in the radial direction of the pair of spokes to provide an additional support of the outer ring. In one embodiment, straight supporting rods are provided. For example, the supporting rods are arranged centered between the first spokes and the second spokes. Hence, in a circumferential direction of the outer ring a distance between the first spoke and the supporting rod of each pair of spokes is the same as a distance between the second spoke and the supporting rod of said pair of spokes. In other embodiments, Y-shaped supporting rods are provided.

In one embodiment, straight supporting rods are provided that extend in radial direction between the crossing point of each pair of spokes and the outer ring. Preferably, the pairs of spokes are evenly distributed, so that in the circumferential direction of the outer ring the distance between the first spoke and the supporting rod of each pair of spokes is the same as a distance between the first spokes and the second spokes of immediately neighboring pairs of spokes. Therefore, the supporting rods allow that the outer ring is supported at a plurality of at least essentially equidistantly arranged regions in the circumferential direction.

In one embodiment, transition regions between the first spokes and the outer ring and between the second spokes and the outer ring are reinforced. Due to the design of the rapier wheel having convexly curved spokes, only local stresses occur, which are not distributed over a large area of the rapier wheel. Hence, by reinforcing only a transition region between the spokes and the outer ring, a durability of the rapier wheel can be increased without or at least without a significant increase of the moment of inertia about the drive shaft and/or the weight of the rapier wheel.

In one embodiment, the number of pairs of spokes is uneven, wherein in particular the number is eleven, thirteen or fifteen. Providing an uneven number of spokes is preferred to minimize warping effects during manufacturing of the rapier wheel and/or during operation of the rapier wheel.

According to a second aspect, a rapier weaving machine having a rapier wheel with pairs of spokes comprising a first spoke and a second spoke is provided, wherein the first spoke and the second spoke extend in opposite directions and cross each other at a crossing point between the inner ring and the outer ring, and wherein the first spoke and the second spoke are each convexly curved toward the outer ring.

<FIG> shows a part of a weaving machine <NUM> with a rapier wheel <NUM> for driving a rapier <NUM>. At the periphery of the rapier wheel <NUM>, two guide blocks <NUM>, <NUM> and an arched guide section <NUM> are provided for guiding the rapier <NUM> at the rapier wheel <NUM>. The rapier wheel <NUM> of <FIG> is shown in isolation in <FIG>.

The rapier wheel <NUM> shown in <FIG> and <FIG> has an inner ring <NUM>, an outer ring <NUM>, and a number of spokes <NUM>, <NUM> extending between the inner ring <NUM> and the outer ring <NUM> and connecting the inner ring <NUM> with the outer ring <NUM>.

The inner ring <NUM> is configured for mounting the rapier wheel <NUM> via the inner ring <NUM> to a drive shaft <NUM>. In the embodiment shown in <FIG> and <FIG>, for this purpose, a number of through holes <NUM> (see <FIG>) are provided in the rapier wheel <NUM>, in particular six evenly distributed through holes <NUM> are provided, for a screw connection <NUM> between the inner ring <NUM> and the drive shaft <NUM>. To this end, for example, a connection ring <NUM> is provided onto which the rapier wheel <NUM> is fixed by six bolts <NUM> extending through the through holes <NUM> and four bolts <NUM> are provided for fixing the connection ring <NUM> to the drive shaft <NUM>.

The outer ring <NUM> is provided with teeth <NUM> configured to engage with the rapier <NUM> for driving the rapier <NUM> back-and-forth.

The spokes <NUM>, <NUM> are arranged crosswise forming pairs of spokes <NUM>, each pair of spokes <NUM> comprising a first spoke <NUM> and a second spoke <NUM>. The first spoke <NUM> and the second spoke <NUM> of each pair of spokes <NUM> cross each other at a crossing point <NUM> between the inner ring <NUM> and the outer ring <NUM>. A radial direction <NUM> (shown by the dotted arrow) through the crossing point <NUM> of a pair of spokes <NUM> is referred to as the radial direction <NUM> of said pair of spokes <NUM>. The first spokes <NUM> and the second spokes <NUM> are all inclined or tilted with respect to the radial direction <NUM>, wherein the first spokes <NUM> and the second spokes <NUM> extend in opposite directions.

In the embodiment shown, the spokes <NUM>, <NUM> are identical in shape, wherein the first spoke <NUM> and the second spoke <NUM> of each pair of spokes <NUM> are arranged symmetrically to the radial direction <NUM> of said pair of spokes <NUM>. Therefore, the crossing points <NUM> of all pairs of spokes <NUM> are arranged on a first imaginary circle <NUM> (shown by a dotted line).

The first spokes <NUM> and the second spokes <NUM> are each convexly curved toward the outer ring <NUM>. As schematically shown in <FIG>, the spokes <NUM>, <NUM> extend entirely along a path which seen in the radial direction <NUM> of the associated pair of spokes <NUM> is above virtual straight lines <NUM>, <NUM> (shown as dotted lines in <FIG>) connecting ends of the spokes <NUM>, <NUM> at the inner ring <NUM> and the outer ring <NUM>. As shown in <FIG>, due to the convex curvature, the crossing point <NUM> of the first spoke <NUM> and the second spoke <NUM> is closer to the outer ring <NUM> than a crossing point <NUM> of the two virtual straight lines <NUM>, <NUM> crossing each other.

In the embodiment shown, a curvature <NUM> (shown by a dotted line) of the spokes <NUM> starts at a center <NUM> of the rapier wheel <NUM> and increases towards the outer ring <NUM>. In the embodiment shown, the curvature <NUM> increases continuously towards the outer ring <NUM>. A curvature <NUM> (shown by a dotted line) of the spokes <NUM> is similar as the curvature <NUM> of the spokes <NUM>.

In use, the rapier <NUM> driven by the rapier wheel <NUM> exerts forces on the outer ring <NUM>. The convexly curved spokes <NUM>, <NUM> arranged in pairs of spokes <NUM> allow to counter tangential forces as well as radial forces exerted on the outer ring <NUM> by the rapier <NUM>, wherein resulting bending stresses on the spokes <NUM>, <NUM> due to external forces can be reduced.

The pairs of spokes <NUM> are evenly distributed about the rapier wheel <NUM>. In the embodiment shown in <FIG> and <FIG>, eleven pairs of spokes <NUM> are provided, wherein first spokes <NUM> and second spokes <NUM> of two immediately neighboring pairs of spokes <NUM> cross at second crossing points <NUM>. The second crossing points <NUM> are arranged on a second imaginary circle <NUM> (shown by a dotted line) having a smaller radius than the first imaginary circle <NUM>.

In the embodiment shown, the second imaginary circle <NUM> is at a region of the inner ring <NUM>, wherein triangular connecting areas <NUM> are formed between the inner ring <NUM> and the first spokes <NUM> and the second spokes <NUM> of the two immediately neighboring pairs of spokes <NUM>. The connecting areas <NUM> in the embodiment shown are closed. In other words, triangles formed by the spokes <NUM>, <NUM> of adjacent pairs of spokes <NUM> and the inner ring <NUM> are filled with material.

In the embodiment shown, transition regions <NUM> between the spokes <NUM>, <NUM> and the outer ring <NUM> are reinforced, for example have an increasing surface near the outer ring <NUM>.

As shown in <FIG> the axial width of the spokes <NUM>, <NUM>, thus the width in the direction of the axis of rotation of the rapier wheel <NUM>, is variable from the inner ring <NUM> towards the outer ring <NUM>. For example, the axial width decreases from the inner ring <NUM> towards the outer ring <NUM>, wherein in particular the axial width of the spokes <NUM>, <NUM> decreases continuously from the inner ring <NUM> towards the outer ring <NUM>. As shown in <FIG> the axial width of the inner ring <NUM> is constant, the axial width of the spokes <NUM>, <NUM> decreases in the radial direction <NUM> towards the outer ring <NUM>, and near the outer ring <NUM> the axial width of the rapier wheel <NUM> increases again via a chamfer <NUM> towards the outer ring <NUM>.

<FIG> shows a second embodiment of a rapier wheel <NUM> having an inner ring <NUM>, an outer ring <NUM>, and a number of convexly curved first spokes <NUM> and second spokes <NUM> extending between the inner ring <NUM> and the outer ring <NUM>. The first spokes <NUM> and the second spokes <NUM> are arranged in pairs of spokes <NUM> having a crossing point <NUM>, wherein in the embodiment shown in <FIG>, thirteen pairs of spokes <NUM> are provided. As in comparison to <FIG> and <FIG> the number of pairs of spokes <NUM> is increased, whereas a diameter of the rapier wheel <NUM> remains at least essentially unchanged, the pairs of spokes <NUM> are arranged closer to each other. Therefore, in the embodiment shown in <FIG>, each first spoke <NUM> crosses second spokes <NUM> of two other pairs of spokes <NUM> at second crossing points <NUM> and third crossing points <NUM>, respectively. The third crossing points <NUM> are arranged on a third imaginary circle <NUM> (shown by a dotted line).

Triangular connecting areas <NUM> are formed between the inner ring <NUM> and the first spokes <NUM> and the second spokes <NUM> of two different pairs of spokes <NUM> that cross each other at the third crossing point <NUM>. The connecting areas <NUM> in the embodiment shown are closed, i.e. filled with material.

In the embodiment shown in <FIG>, a straight supporting rod <NUM> is provided that extends in radial direction <NUM> between the crossing point <NUM> of each pair of spokes <NUM> and the outer ring <NUM>. In a circumferential direction of the outer ring <NUM>, a distance D1 between the first spoke <NUM> and the supporting rod <NUM> of each pair of spokes <NUM> is the same as a distance D2 between the second spoke <NUM> and the supporting rod <NUM> of said pair of spokes <NUM>. In the embodiment shown in <FIG>, the pairs of spokes <NUM> are evenly distributed and a number of pairs of spokes <NUM> can be chosen with respect to a diameter of the rapier wheel <NUM>, so that in the circumferential direction of the outer ring <NUM> the distance D1 between the first spoke <NUM> and the supporting rod <NUM> of each pair of spokes <NUM> is the same as a distance D3 between the first spokes <NUM> and the second spokes <NUM> of immediately neighboring pairs of spokes <NUM>.

<FIG> shows a third embodiment of a rapier wheel <NUM> having an inner ring <NUM>, an outer ring <NUM>, and a number of convexly curved first spokes <NUM> and second spokes <NUM> extending between the inner ring <NUM> and the outer ring <NUM>. The first spokes <NUM> and the second spokes <NUM> are arranged in pairs of spokes <NUM> having a crossing point <NUM>, wherein in the embodiment shown in <FIG>, fifteen pairs of spokes <NUM> are provided. As in comparison to <FIG>, the number of pairs of spokes <NUM> is further increased, whereas a diameter of the rapier wheel <NUM> remains at least essentially unchanged, the pairs of spokes <NUM> are arranged closer to each other. Therefore, in the embodiment shown in <FIG>, each first spoke <NUM> crosses second spokes <NUM> of four other pairs of spokes <NUM> at second crossing points <NUM>, third crossing points <NUM>, fourth crossing points <NUM> and fifth crossing points <NUM>, respectively. The fifth crossing points <NUM> are arranged on a fourth imaginary circle <NUM> (shown by a dotted line).

Triangular connecting areas <NUM> are formed between the inner ring <NUM> and the first spokes <NUM> and the second spokes <NUM> of different pairs of spokes <NUM> that cross each other at the fifth crossing point <NUM>. The connecting areas <NUM> in the embodiment shown are closed, i.e. filled with material. In the embodiment shown in <FIG>, supporting rods <NUM> are provided that extend between the crossing points <NUM> of the pairs of spokes <NUM> and the outer ring <NUM>.

The rapier wheels <NUM> shown in the above described embodiments are all flat, i.e. all spokes <NUM>, <NUM> as well as all crossing points <NUM>, <NUM>, <NUM>, <NUM>, <NUM> are arranged in a common plane.

<FIG> shows a fourth embodiment of a rapier wheel <NUM> similar to the rapier wheel shown in <FIG> and having an inner ring <NUM>, an outer ring <NUM>, and a number of convexly curved first spokes <NUM> and second spokes <NUM> extending between the inner ring <NUM> and the outer ring <NUM>. As can be seen the thickness of the spokes <NUM>, <NUM> along the plane of the rapier wheel <NUM> decreases towards the outer ring <NUM>, wherein in particular the thickness of the spokes <NUM>, <NUM> decreases continuously towards the outer ring <NUM>. For example, Y-shaped supporting rods <NUM> are provided that extend between the crossing points <NUM> of the pairs of spokes <NUM> and the outer ring <NUM>.

Claim 1:
Rapier wheel for a rapier weaving machine having an inner ring (<NUM>), an outer ring (<NUM>), and a number of spokes (<NUM>, <NUM>), wherein the inner ring (<NUM>) is configured for mounting the inner ring (<NUM>) to a drive shaft (<NUM>), wherein the outer ring (<NUM>) is provided with teeth (<NUM>) configured for engaging with a rapier (<NUM>) for driving the rapier (<NUM>), wherein the spokes (<NUM>, <NUM>) extend between the inner ring (<NUM>) and the outer ring (<NUM>) and connect the inner ring (<NUM>) with the outer ring (<NUM>), wherein the spokes (<NUM>, <NUM>) are arranged crosswise in pairs of spokes (<NUM>) comprising a first spoke (<NUM>) and a second spoke (<NUM>), and wherein the first spoke (<NUM>) and the second spoke (<NUM>) extend in opposite directions and cross each other at a crossing point (<NUM>) between the inner ring (<NUM>) and the outer ring (<NUM>), characterized in that the first spoke (<NUM>) and the second spoke (<NUM>) are each convexly curved toward the outer ring (<NUM>).