EP1473391B1 - Weft insertion system and method - Google Patents

Description

The invention relates to a system and a method for introducing a weft thread into a shed of an air jet loom according to the preamble of claim 1 and 12 and an air jet loom with such a system and for carrying out such a method.

In an air jet loom, the weft yarn drawn from a yarn store is accelerated by main and tandem nozzles and entered into a shed in which it is transported further by so-called auxiliary or relay nozzles. In conventional air jet looms the relay nozzles are switched on and off by a preselected profile fixedly connected to the rotation of the machine main shaft. It is left to the Webmaster to adapt this profile optimally for a particular article, whereby more attention is often paid to the fabric quality than to the air consumption.

Document EP 0 554 222 A1 describes a method for controlling the weft insertion for a jet loom with a plurality of auxiliary nozzles and a plurality of weft guards arranged in the shed to detect the time at which the leading end of a weft inserted at the location of one of the weft guards arrives. In the described method, the detected time is compared with a predetermined reference arrival time and the injected compressed air before and after the weft guard arranged auxiliary nozzles or groups of auxiliary nozzles on the basis of the desired-actual value comparison changed, ie the auxiliary nozzles supplied with low, normal or elevated pressure. In case of early arrival, the blowing time of the auxiliary nozzles can be shortened to delay the weft thread.

The method described in EP 0 554 222 A1 is relatively complicated, since it requires three separate compressed air supplies for the auxiliary nozzles. Furthermore, the simultaneous application of several groups of auxiliary nozzles allows a gentle acceleration of the weft thread, but this is associated with a massive increase in the consumption of compressed air. In addition, the arrangement of a variety of weft guards in the shed is problematic because they damage the warp threads and thereby can affect the quality of the fabric.

Document WO 92 04490 discloses a system and method for feeding a weft in an air jet loom in which the signals of one or more winder counters are used to calculate the length of weft weft drawn and to activate turret nozzles based on the calculated length. A disadvantage of such a system and method is the limited accuracy of the calculated length, since the turn counter signals arrive at a time interval and thus only discrete values are available for the calculation of the length.

The object of the invention is to provide a system and a method for entering a weft thread in a shed of an air jet loom available, which have a simple and compressed air consumption optimized control of the air nozzles, which manage with a relatively low cost of system components, and the one ensure perfect fabric quality. Another object of the invention is to provide an air jet loom with such a system and for carrying out such a method.

This object is achieved according to the invention by the system defined in claim 1 and the method defined in claim 12 and by the air jet loom defined in claim 14.

The system according to the invention for introducing a weft thread into a shed of an air jet loom comprises a thread store, a measuring device for detecting the weft thread drawn from the thread store, a plurality of air nozzles for introducing the weft thread and a controller connected to the measuring device for supplying compressed air to the air nozzles as a function of measured values of the measuring device. In this case, the air nozzles are assigned switch-on, and the controller is designed such that one or more of the air nozzles are pressurized with compressed air, as soon as with the aid of Measured values formed predictor value for the position of the weft tip, in which the position of the weft thread tip is extrapolated to the arrival of the next measured value, reaches the switch-on of the respective air nozzle or air nozzles.

The switch-on point of an air nozzle preferably corresponds to the position of the air nozzle in the shed, or in the case of a group of air nozzles, which are simultaneously exposed to compressed air, to the position of the first air nozzle of the group to be passed by the weft thread tip.

Preferably, the predictive value for the position of the weft tip contains a safety value, which depends in particular on the resolution of the measuring device and / or the switch-on for the pressure build-up in the region of the respective air nozzle and / or the speed of the weft tip.

Preferably, the predictor values for the position of the weft tip and / or the speed of the weft tip are formed on the basis of the measured values determined for the current weft thread.

In a preferred embodiment, the air nozzles are assigned switch-off points, wherein the controller switches off one or more of the compressed air nozzles as soon as the prediction value for the position of the weft tip formed on the basis of the measured values reaches the switch-off point of the respective air nozzle or air nozzles.

The switch-off point preferably has a predetermined distance from the switch-on point of the corresponding air nozzle or air nozzles, and / or the switch-off point corresponds to the position of a subsequent air nozzle in the shed.

In a further preferred embodiment, the thread store is designed as a drum store, on which the weft thread can be wound, wherein the measuring device is preferably arranged on the thread store or in the vicinity of the thread store and comprises at least one sensor, to detect the withdrawal of turns and / or partial turns from the drum store.

Preferably, at least one additional sensor is provided in the path of the weft to detect the position of the weft tip within the shed, and / or a weft detector at the catch end of the shed.

In a further preferred embodiment, the controller additionally comprises a control device, which is connected to the sensors of the measuring device and / or the sensor in the path of the weft thread and / or the weft thread monitor, from the measured values of the sensors and / or the weft thread monitor for the entry The time required for the weft to be determined and compared with a predetermined picking time, and to control the pressure and / or the blowing time and / or the flow of the air nozzles with the difference between the time required for the entry of the weft thread and the predetermined picking time.

In the method according to the invention for introducing a weft thread into a shed of an air jet loom using a system comprising a thread store, a measuring device for detecting the weft thread drawn from the thread store, a plurality of air nozzles for feeding the weft thread and a controller, the compressed air supply of the air nozzles becomes controlled as a function of measured values of the measuring device,
wherein the air nozzles are assigned switch-on points,
wherein predictive values for the position of the weft tip are formed with the aid of the measured values, the position of the weft tip being extrapolated until the arrival of the next measured value to form the predictive value,
in particular, a safety value is included in the predictor values for the position of the weft tip, and
wherein the controller pressurizes one or more of the air nozzles with compressed air as soon as a predictive value for the position of the weft tip formed with the aid of the measured values reaches the switch-on point of the relevant air nozzle or air nozzles.

In addition, in a preferred embodiment, the time required for the picking of the weft yarn is determined and compared with a predetermined picking time, and the difference between the time taken for picking the picking yarn and the predetermined picking time is used to determine the pressure and / or the blowing time and / or to regulate the flow rate of the air nozzles.

Furthermore, the invention comprises an air jet loom with a system according to one of claims 1 to 11.

The system according to the invention has the advantage that it is essentially made up of system components that are currently available as standard on most air-jet looms. As a new system component only an addition to the control program is necessary, in which the functions mentioned in the characterizing part of claims 1 and 12 are implemented. In addition, the system and method according to the invention make it possible to substantially reduce the compressed air consumption compared with older machines, without having to accept compromises in fabric quality, since the weft yarn is no longer subjected to compressed air as necessary. The formation of a predictor value for the position of the weft tip on the basis of measured values that can be determined outside of the shed, makes it possible to make corrections during the current weft insertion and to dispense with sensors and weft thread monitor in the shed. This avoids impairment of the quality of the fabric by sensors and weft guards arranged in the shed.

Further advantageous embodiments will become apparent from the dependent claims and the drawings.

Fig. 1

ein Ausführungsbeispiel einer Luftdüsenwebmaschine mit einem System zum Eintragen eines Schussfadens gemäss vorliegender Erfindung,

Fig. 2a

Windungszählersignal während der ersten Hälfte des Schusseintrages in einem System gemäss vorliegender Erfindung,

Fig. 2b

aus dem Windungszählersignal berechnete Geschwindigkeit der Schussfadenspitze,

Fig. 2c

Prädiktorwerte für die Position der Schussfadenspitze, welche auf Grund des Windungszählersignals berechnet wurden,

Fig. 3

zwei Schusseintragsprofile in einem System gemäss vorliegender Erfindung,

Fig. 4

Ausführungsbeispiel eines Systems gemäss vorliegender Erfindung,

Fig. 5

Detailansicht der Schussfadenspitze zu dem in Fig. 4 gezeigten Ausführungsbeispiel, und

Fig. 6

Blockschaltbild einer Ausführungsvariante der Regel- und Steuerkreise zu dem in Fig. 4 gezeigten Ausführungsbeispiel.

In the following the invention will be explained in more detail with reference to the embodiments and with reference to the drawing. Show it:

Fig. 1

An embodiment of an air jet loom with a system for introducing a weft thread according to the present invention,

Fig. 2a

Winding counter signal during the first half of the weft insertion in a system according to the present invention,

Fig. 2b

speed of weft tip calculated from the turn counter signal,

Fig. 2c

Predictor values for the position of the weft tip, which were calculated on the basis of the turn counter signal,

Fig. 3

two weft insertion profiles in a system according to the present invention,

Fig. 4

Embodiment of a system according to the present invention,

Fig. 5

Detail view of the weft tip to the embodiment shown in Fig. 4, and

Fig. 6

Block diagram of an embodiment of the control and control circuits to the embodiment shown in Fig. 4.

Fig. 1 shows an embodiment of an air jet loom 1 with a system according to the present invention. The system for inserting a weft thread 2 into a shed (not shown in FIG. 1) comprises a thread store 21 and a measuring device 23.1, 23.2 in order to detect the weft thread 2 withdrawn from the thread store and, in particular, the length and / or speed of the withdrawn thread To detect weft, which measuring device is preferably arranged outside the shed, for example, at the thread store 21 or in the vicinity of the thread store. Further, the system comprises a plurality of air nozzles 3, 4, 5.1 ac to 5.na-c for entering the weft yarn 2 and a Control 10, which is connected to the measuring device 23.1, 23.2, in order to control the compressed air supply of the air nozzles 3, 4, 5.1ac to 5.na-c as a function of measured values of the measuring device 23.1, 23.2. In a preferred embodiment, the yarn store 21 is designed as a drum store, which comprises a drum 22 on which the weft thread is wound up. The measuring device is advantageously arranged in the vicinity of the drum store 21 in this embodiment and comprises at least one sensor 23.1, 23.2 in order to detect the withdrawal of turns and / or partial turns from the drum 22. The sensors 23.1, 23.2 are therefore referred to below as "turn counter". In one embodiment, the drum 22 has a circumference of 0.5 m and the measuring device is provided with typically three or more sensors 23.1, 23.2, which are arranged at equal angular intervals around the drum.

In the exemplary embodiment, the air nozzles comprise a main nozzle 3, a tandem nozzle 4 and relay nozzles 5.1 ac to 5.na-c to accelerate the weft yarn 2 withdrawn from the yarn store 21 by means of the main nozzle 3 and tandem nozzle 4 and enter into the shed and in the shed by means of Shuttle nozzles 5.1 ac to 5.na-c continue to transport. Instead of the main and tandem nozzles 3, 4 may also be provided only a single main nozzle, or it may be several consecutive nozzles, often referred to as pre-nozzles and main nozzles, arranged one behind the other to accelerate the weft. Of course, a plurality of juxtaposed main nozzles 3 may be provided to alternately enter different weft threads 2, which may differ in color, fineness, texture and material. The relay nozzles 5.1ac to 5.na-c are often combined in groups of two to five or more nozzles, wherein the nozzles of a group are each supplied in common via a control valve 15.1 to 15.n, for example a solenoid valve, with compressed air. Expediently, the control valves 15.1 to 15.n are connected to a compressed air accumulator and / or distributor 12, which is supplied with compressed air via a pressure line 11. It is also possible to provide a plurality of compressed air reservoirs and / or distributors 12, which can have different pressure levels.

In one embodiment variant, the system for introducing a weft thread comprises a thread brake 9, which is controlled by the controller 10. By means of the yarn brake 9, the weft thread 2 can be braked, in particular towards the end of the weft insertion, when the weft tip approaches the Schussankunftsseite the shed. In addition, on the Schussankunftsseite the shed a weft guard 7 may be provided to detect the arrival of the registered weft yarn 2.

Further, the air-jet weaving machine 1 of the embodiment comprises a reed 8 to strike the registered weft 2 and a respective cutting device on both sides of the shed to cut off the weft 2 after striking. Advantageously, at the catch end of the shed a stretching and / or catching nozzle 6 may be provided to extend the registered weft thread 2 to the sheet stop and / or dispose of the weft end after cutting.

In the embodiment shown in Fig. 1, the control valves 13, 14, 15.1 to 15.n are controlled by the controller 10 such that the air nozzles 3, 4, 5.1ac to 5.na-c are supplied at the right time with appropriate amounts of air to enter the weft 2 in the shed. FIG. 3 shows two different entry profiles A and B. The first horizontal bar 3 'represents the air quantity of the main nozzle 3, the second bar 4' the air quantity of the tandem nozzle 4, the third bar 5.1'ac the air quantity of the relay nozzles 5.1 ac, etc In this case, the thickness of the beam corresponds to the respective pressure Δp applied to the respective nozzle, the length of the beam of the blowing time ΔT and the position of the beam in the horizontal direction of the position of the switch-on and switch-off times in the time sequence of the weft insertion. As can be seen from the upper graph of FIG. 3, the same entry time T _{e is} achieved with both entry profiles. Nevertheless, the compressed air consumption for the two entry profiles A and B is different. If all relay nozzles 5.1 ac to 5.na-c are of the same design and are acted upon by the same pressure Δp _j , the compressed air consumption of the relay nozzles 5.1 ac to 5.na-c is proportional to the sum ΣΔT _{j of} the individual blowing times ΔT _j .

4 shows an exemplary embodiment of a system for introducing a weft thread 2 according to the present invention, wherein only those components are shown which are in direct contact with the weft thread and / or accelerate, transport or decelerate it and / or detect it. The individual components of this system have already been described in the context of the embodiment of FIG. The length L ₀ denotes the length of the weft thread 2 between the yarn store 21 and the shed and the length L _e the length of the inserted weft thread in the shed.

Fig. 2a shows a typical course of the Windungszählersignals during the first half of the weft insertion in a system according to the embodiment described below. The thread store 21 in this embodiment comprises a drum 22 having a circumference u of 0.50 m, on which the weft thread to be introduced is wound up. The measuring device comprises six light sensors 23.1, 23.2, which are arranged annularly at the outlet of the drum store 21 and detect the passing weft thread, ie 6 pulses are generated per drawn winding. The result for the determination of the withdrawn weft length L or the position x _{F of} the weft tip is a resolution e _x of $$e_x=\frac{u}{6}=\frac{\mathrm{00:50}\mathrm{m}}{6}=0083\mathrm{m}$$

The time interval Δt _i between two rising edges of the Windungszählersignals is proportional to the inverse of the average speed of the yarn tip v _F in this time interval, ie $$v_F\left(t_i\right)=e_x\cdot \Delta t_i^{-1}$$

A typical course of the velocity v _F during a weft insertion is shown in FIG. 2b.

mit

v _F (t _k ) =

Geschwindigkeit der Fadenspitze,

T _Zyklus =

Zykluszeit der Steuerung, und

k =

Index des Steuerzyklus.

During weft insertion, as shown in Fig. 2a, the turn counter signal provides at certain time intervals discrete pulses by which the instantaneous position of the weft tip is determined can. In some cases, the Windungszählersignal can be filtered before the evaluation. In order to determine the position of the weft tip continuously, in the exemplary embodiment, the position determined by the Windungszählersignal the weft tip is extrapolated until the arrival of the next pulse, for example by means of the following formula (3). The position ( x _F ) of the weft tip determined in this way is referred to below as the "predictive value for the position of the weft tip". $$x_F\left(t_{k+1}\right)=x_F\left(t_k\right)+v_F\left(t_k\right)\cdot T_{\mathit{cycle}}$$

With

v _F ( t _k ) =

Speed of the thread tip,

T _cycle =

Cycle time of the controller, and

k =

Index of the control cycle.

A typical profile of the predictor value x _F for the position of the weft tip is shown in FIG. 2c.

The formation of the mentioned predictive value x _F for the position of the weft tip will be explained in detail below, since this predictor value is of central importance in the system and method according to the invention. FIG. 5 shows a detail view of the weft tip of the embodiment shown in FIG. 4. At the time t _k , the tip of a weft thread 2 is located at the position x _F ( t _k ) within the shed. By means of the air nozzles 3, 4, 5.1ac to 5.na-c (not shown in Fig. 5), the weft yarn 2 in a weft channel 18 which is formed in the reed 8 (see Fig. 1), further transported. In the present embodiment, the movement of the weft thread according to the weft insertion direction extends from left to right. Starting from the current position x _F ( t _k ), a predictor value x _F (t _{k + 1} ) is formed for the position of the weft tip, for example by means of the formula (3). The starting position x _F (t _k ) may be a position detected, for example, by a sensor arranged in the shed, or derived directly from a new pulse of the winding counter or, if at time t _k, no such pulse has arrived to the previous predictor value.

Advantageously, the predictor value for the position of the weft tip contains a safety value which depends in particular on the resolution e _{x of} the measuring device and / or on the switch-on time T _Vent for the pressure buildup in the area of the respective air nozzle and / or on the speed v _F ( t _k ) of the weft tip. In this case, the distance s _x , which is covered during the switch-on time T _Vent , depends on the speed v _F ( t _k ) of the weft tip: $$s_x\left(t_{k+1}\right)=v_F\left(t_k\right)\cdot T_{\mathit{Vent}}$$

A predictor value x _F (t _{k + 1} ) for the position of the weft tip, which contains a corresponding safety value, can be calculated, for example, according to the following formula: $$\begin{array}{ll}{x}_F\left(t_{k+1}\right)& =x_F\left(t_k\right)+v_F\left(t_k\right)\cdot T_{\mathit{cycle}}+s_x+e_x\\ \mathrm{}& =x_F\left(t_k\right)+v_F\left(t_k\right)\cdot \left(T_{\mathit{cycle}}+T_{\mathit{Vent}}\right)+e_x\end{array}$$

In the exemplary embodiment shown in FIG. 4, the air nozzles 3, 4, 5.1 ac to 5.na-c are assigned switch-on points x _j , which are specially marked in FIG. 5, the controller 10 having one or more of the air nozzles 3, 4, 5.1 ac to 5.na-c supplied with compressed air as soon as a formed by means of the measured values, for example by means of Windungszählersignals, formed predictor value x _F (t _{k + 1} ) for the position of the weft tip reaches the switch-on x _{j of} the respective air nozzle or air nozzles , That is, an air nozzle j or group of air nozzles is turned on, if $${\mathit{X}}_F\left(t_{k+1}\right)\ge {\mathit{X}}_j$$

Advantageously, the switch-on point x _{j of} an air nozzle corresponds to the position of the air nozzle in the shed, or in the case of a group of air nozzles, which are simultaneously exposed to compressed air, to the position of the first air nozzle of the group. The above-mentioned safety value or parts thereof can also be taken into account when determining the switch-on point x _j instead of forming the predictor value x _F (t _{k + 1} ) .

In a preferred embodiment, the air nozzles 3, 4, 5.1 ac to 5.na-c are assigned switch-off points, wherein the controller 10 switches off one or more of the compressed air nozzles as soon as a predictor value x _F (t _{k + 1} ) reaches the switch-off point of the respective air nozzle or air nozzles for the position of the weft tip. The switch-off point preferably has a predetermined distance from the switch-on point of the corresponding air nozzle or air nozzles, and / or the switch-off point corresponds to the position of a subsequent air nozzle in the shed. In particular, it may be expedient to couple the switch-off points of the main and / or tandem nozzles 3, 4 with the switch-off point of a relay nozzle 5.1 ac to 5.na-c, for example by switching off the main and / or tandem nozzles simultaneously with the relevant relay nozzle ,

Particularly with larger weaving widths, at least one additional sensor is advantageously provided in the travel path of the weft thread 2 in order to detect the position of the weft thread tip.

In a further preferred embodiment, the controller 10 additionally comprises a control device, which is connected to the sensors 23.1, 23.2 of the measuring device and / or the sensor in the path of the weft thread 2 and / or the weft thread monitor 7 in order to obtain from the measured values of the sensors and / or or the weft detector to determine the time required for the entry of the weft yarn 2 T _e and to compare with a predetermined target entry time, and with the difference between the time required for the entry of the weft thread and the predetermined target entry time the pressure and / or to control the blowing time and / or the flow rate of the air nozzles 3, 4, 5.1 ac to 5.na-c. A corresponding control device, which is known under the name "Time Controller", is described, for example, in US Pat. No. 4,446,893. The control can be designed so that the difference between the time required for the entry of the weft thread and the predetermined target entry time is minimal or within predetermined values. In a preferred development, the time T _e required for the entry of the weft thread 2 becomes over a number of consecutive weft entries recorded and determines a mean entry time. For a new article, the thus determined average entry time can be used as the target entry time. Furthermore, it is also possible to regulate the pressure and / or the blowing time and / or the flow of the air nozzles 3, 4, 5.1 ac to 5.na-c with the difference between a mean picking time and a predetermined set picking time.

6 shows a block diagram of a variant of the control and control circuits to the embodiment shown in Fig. 4. The reference numeral 30 summarizes the components of the weft insertion system shown in FIG. By means of the separately shown in Fig. 6 sensors 23.1, 23.2, the length of the withdrawn weft yarn is detected and the output signal of these sensors is fed to a control device 10.1. The control device 10.1 forms from the output signal predictor values for the position of the weft tip and controls in the manner described above, the switching on and off of the relay nozzles. The signal path 101 forwards the switch-on signals for the relay nozzles to the corresponding control valves 15.1 to 15.n. Another signal path 102 directs shutdown signals for the relay nozzles to the corresponding control valves. In some cases, the control device can also generate switch-off signals for the main and tandem nozzles in order to control the switching off of the corresponding compressed air supply 13, 14. A separately shown in Fig. 6 weft detector 7 detects the arrival of the weft tip on the Schussankunftsseite the shed. The signal of the weft detector 7 is fed to a control device 10.2, which, as described above, from the signal of the weft detector determines the time required for the entry of the weft thread and compared with a predetermined target entry time, and compared with the difference between the for the Entry of the weft thread required time and the target entry time the pressure and / or the blowing time, or switching off, the air nozzles controls. The signal path 104 passes the control signal for the pressure to the compressed air supply 13, 14 of the main and tandem nozzles. The compressed air supply 13, 14 includes occasionally adjustable and / or controllable pressure regulator, mass flow controller and / or control valves. Between the control device 10.2 and the compressed air supply 13, 14 of the main and tandem nozzles, a further signal path 103 may be provided be over which the switching off of the main and tandem nozzles can be controlled.

In an advantageous embodiment variant, the pressure of the main and tandem nozzles is set manually and the switching off of the main and tandem nozzles is regulated by means of the regulating device 10.2 as a function of the time required for the entry of the weft thread. The switching on of the main and tandem nozzles takes place in contrast to a predetermined time, which may be coupled, for example, with the main machine shaft.

In a further advantageous embodiment, the pressure of the main and tandem nozzles is regulated by means of the control device 10.2 as a function of the time required for the entry of the weft thread. The main and tandem nozzles are turned on at a predetermined time, which may be coupled to, for example, the engine main shaft, and turned off by the control device 10.1 in response to a predictor value for the position of the weft tip. In particular, it may be expedient in this embodiment to couple the switch-off times of the main and / or tandem nozzles with the switch-off time of a relay nozzle, for example by switching off the main and / or tandem nozzles simultaneously with the relevant relay nozzle.

Further advantageous embodiments are obtained by controlling the pressure and / or the switch-off of the relay nozzles by means of the control device 10.2 in dependence on the time required for the entry of the weft thread. Instead of the pressure, the flow of the corresponding air nozzles can be regulated in all previously mentioned embodiments.

The above list of variants is in no way conclusive. By appropriate modification of the block diagram shown in Fig. 6, further embodiments can be derived, all of which have the advantages of the inventive system and method, and in particular an economical operation of Air jet loom allow by the compressed air consumption compared to older machines can be significantly reduced.

Claims (14)

1. A system for inserting a weft thread into a shed of an air jet weaving machine (1), said system including a thread store (21), a measuring apparatus (23.1, 23.2) in order to be able to measure the weft thread (2) which is drawn off from the thread store (21), a plurality of air nozzles (3, 4, 5.1a-c to 5.na-c) for the insertion of the weft thread (2) with which switch on points (x_j) are associated and a control system (10) which is connected to the measuring apparatus (23.1, 23.2) in order to control the compressed air supply of the air nozzles (3, 4, 5.1a-c to 5.na-c) in dependence on measured values of the measuring apparatus (23.1, 23.2), characterized in that the control system (10) is designed to charge one or more of the air nozzles (3, 4, 5.1a-c to 5.na-c) with compressed air as soon as a predictor value (x _F ) formed with the help of the measured values for the position of the weft thread tip, in which the position of the weft thread tip until entry of the next measured value is extrapolated, reaches the switch on point (x _j ) of the relevant air nozzle or air nozzles respectively.
2. A system in accordance with claim 1, wherein the air nozzles include at least one main nozzle (3) and/or tandem nozzle (4) and one or more relay nozzles (5.1a-c to 5.na-c), wherein switch on points (x _j ) are associated with the relay nozzles (5.1a-c to 5.na-c), and wherein the control system (10) charges one or more of the relay nozzles (5.1a-c to 5.na-c) with compressed air as soon as a predictor value (x _F ) for the position of the weft thread tip which is formed with the help of the measured values reaches the switch on point (x _j ) of the relevant relay nozzle or relay nozzles.
3. A system in accordance with claim 1 or claim 2, with the switch on point (x _j ) of an air nozzle corresponding to the position of the air nozzle in the shed or, in the case of a group of air nozzles (5.1a-c to 5.na-c) which are charged with compressed air at the same time, to the position of the first air nozzle (5.1a to 5.na) of the group.
4. A system in accordance with any one of the claims 1 to 3, with the predictor value (x _F ) for the position of the weft thread tip containing a safety value or factor which depends in particular on the resolution of the measuring apparatus and/or on the switch on time for the pressure build up in the region of the relevant air nozzle and/or on the speed (v _F ) of the weft thread tip.
5. A system in accordance with any one of the claims 1 to 4, with the predictor value for the position (x _F ) of the weft thread tip and/or the speed (v _F ) of the weft thread tip being formed as a result of the measured values which are determined for the current weft thread (2).
6. A system in accordance with any one of the claims 1 to 5, with switch off points being associated with the air nozzles (3, 4, 5.1a-c to 5.na-c), with the control system (10) switching off one or more of the air nozzles which are charged with compressed air as soon as the predictor value (x _F ) for the position of the weft thread tip which is formed as a result of the measured values reaches the switch off point of the relevant air nozzle or air nozzles respectively and, in particular, with the switch off point having a predetermined distance from the switch on point of the relevant air nozzle or air nozzles respectively, and/or with the switch off point corresponding to the position of a subsequent air nozzle in the shed.
7. A system in accordance with any one of the claims 1 to 6, with the air nozzles (3, 4, 5.1a-c to 5.na-c) including at least one main nozzle (3) and/or tandem nozzle (4) and one or more relay nozzles (5.1a-c to 5.na-c), and with it being possible to couple the switch off points of the main nozzle (3) and/or tandem nozzle (4) to the switch off point of a predetermined relay nozzle (5.1a-c to 5.na-c).
8. A system in accordance with any one of the claims 1 to 7, with the thread store (21) being formed as a drum store onto which the weft thread can be wound, and with the measuring apparatus being arranged at the thread store (21) and including at least one sensor (23.1, 23.2) in order to be able to measure the draw off of windings and/or of partial windings from the drum store (22).
9. A system in accordance with any one of the claims 1 to 8, with at least one additional sensor being provided in the path of travel of the weft thread in order to be able to measure the position of the weft thread tip, and/or a weft thread monitor (7) on the weft thread arrival side of the shed.
10. A system in accordance with any one of the claims 1 to 9, with the system additionally including a thread brake (9) in order to be able to brake the weft thread (2) in particular towards the end of the weft insertion when the weft thread tip approaches the weft thread arrival side of the shed.
11. A system in accordance with any one of the claims 1 to 10, with the control system (10) additionally including a regulation device (10.2) which is connected to the sensors (23.1, 23.2) and/or to the sensor in the path of travel of the weft thread and/or to the weft thread monitor (7) in order to be able to determine, from the measurement values of the sensors and/or of the weft thread monitor (7), the time required for the insertion of the weft thread (2) and to be able to compare it with a predetermined desired insertion time, and in order to be able to regulate the pressure and/ or the blowing time and/ or the flow through the air nozzles (3, 4, 5.1a-c to 5.na-c) using the difference between the time required for the insertion of the weft thread (2) and the desired insertion time.
12. A method for the insertion of a weft thread into a shed of an air jet weaving machine (1), in which method the weft thread (2) is drawn off from a thread store (21), the drawn off weft thread (2) is measured with the help of a measuring apparatus (23.1, 23.2), the weft thread (2) is inserted into the shed by means of a plurality of air nozzles (3, 4, 5.1a-c to 5.na-c) and a control system (10) controls the compressed air supply of the air nozzles (3, 4, 5.1a-c to 5.na-c) in dependence on measured values of the measuring apparatus (23.1, 23.2), wherein switch on points (x _j ) are associated with the air nozzles (3, 4, 5.1a-c to 5.na-c); characterized in that, with the help of the measured values, predictor values (x _F ) for the position of the weft thread tip are formed, with the position of the weft thread tip prior to arrival of the next measured value being extrapolated to form the predictor value; in that, in particular, a safety value or factor is contained in the predictor values (x _F ) for the position of the weft thread tip; and in that the control system (10) charges one or more of the air nozzles with compressed air as soon as a predictor value (x _F ), formed with the help of the measured values for the position of the weft thread tip, reaches the switch on point (x _j ) of the relevant air nozzle or air nozzles respectively.
13. A method in accordance with claim 12, with the time which is required for the insertion of the weft thread (2) being additionally determined and compared with a predetermined desired insertion time, and with the difference between the time required for the insertion of the weft thread (2) and the desired insertion time being used in order to regulate the pressure and/or the blowing time and/or the flow through the air nozzles (3, 4, 5.1a-c to 5.na-c).
14. An air jet weaving machine (1) including a system in accordance with any one of the claims 1 to 11.

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