JP5356950B2 - Weft thread gripping device in air jet loom - Google Patents

Abstract

The present invention relates to a weft holding device in a jet pick loom. Particularly, the invention discloses a weft holding device suitable for a jet pick loom that weft is jetted from a pick main nozzle through air jet to pick, wherein the pick main nozzle is provided with an accelerating tube, and the weft holding device is provided with a holding mechanism for mechanically holding weft. When a first holding air supply part is switched to supply holding air to a pressure leading-in chamber and a second holding air supply part is switched to stop discharging holding air from the pressure chamber, the holding mechanism holds weft. When the first holding air supply part is switched to stop supplying holding air to a pressure leading-in chamber and the second holding air supply part is switched to discharge holding air from the pressure chamber to a micro-injection path, the holding mechanism releases the weft.

Description

  The present invention relates to a weft gripping device in an air jet loom in which wefts are injected from a weft insertion main nozzle by jetting of weft insertion air of a weft insertion main nozzle having an acceleration pipe.

  For example, Patent Documents 2 and 3 disclose a weft drop prevention device that performs fine air injection from the weft insert main nozzle in order to prevent weft drop from the weft insert main nozzle. In the devices disclosed in Patent Documents 2 and 3, fine injection is performed from the main nozzle for weft insertion during the weft insertion standby, and this fine injection prevents the weft from coming off from the main nozzle for weft insertion.

  In addition, when wefting a highly elastic weft such as a spandex yarn, the weft is stretched by injecting high-pressure air from the main nozzle for weft insertion to prevent the shrinkage of the highly elastic weft. it can. However, when weft insertion is completed and the weft waits for weft insertion, the injection from the main nozzle for weft insertion is switched from high pressure injection to fine injection, so it is not possible to suppress the shrinkage of the highly elastic weft. Therefore, it becomes necessary to increase the fine injection pressure during the weft insertion standby.

  When the fine injection pressure during the weft insertion standby is increased, the weft is stationary, so that the weft portion that receives the action of the high injection pressure may be twisted back, or the covered yarn may be wrapped around the elastic yarn that is the core material. In the case of a spandex yarn wound with (decorating yarn), there is a problem that the covered yarn is blown away by the fine injection action during standby insertion. Such a defect causes damage to the woven fabric.

  Patent Document 4 discloses an apparatus for pressing and holding a weft thread against a fixed wall by an air flow. This gripping method lacks the certainty of weft thread gripping as in the devices disclosed in Patent Documents 2 and 3.

  For example, Patent Documents 1, 5, and 6 disclose a weft removal prevention device that mechanically grips a weft that is waiting for weft insertion in order to prevent weft removal from the main nozzle for weft insertion. Mechanical gripping is performed using air pressure. In the devices disclosed in Patent Documents 1, 5, and 6, since the wefts waiting to be inserted are mechanically sandwiched and actively gripped, it is possible to suppress the shrinkage of the highly elastic wefts during gripping.

JP-A-57-128236 JP-A-5-279940 Japanese Patent Laid-Open No. 5-28739 JP-A-11-200193 JP 2008-144336 A JP 2008-508432 A

  However, in the devices disclosed in Patent Documents 1, 5, and 6, the weft is contracted upstream after the mechanically sandwiched weft is released from the gripping action until the weft insertion is started. It will be in a loose state. This increases the variation of the weft insertion start time and the weft insertion end time, thereby making it easier to generate a weft insertion error. Even in the case of wefts with low stretchability, the wefts are once loosened in the main nozzle for weft insertion, so that the same problem as with wefts with high stretchability occurs.

  In order to reduce such variation, when the weft is released from the gripping action after waiting for the weft insertion injection timing, the response of the weft gripping device is slow, so the weft gripping plate becomes a resistance and the main for weft insertion The jet flows backward toward the upstream side of the nozzle. Therefore, there is a problem that the weft is damaged or the weft insertion becomes unstable.

  In order to prevent the backflow of the jet, if the jetting timing of the weft insertion air at the weft insertion main nozzle is made earlier than usual, loosening of the weft can be suppressed, but strong jet aerodynamic force is waiting for weft insertion. Since it acts on a stationary weft, a weft with a weak twist or a weft with a weak yarn strength is likely to cause yarn breakage due to twisting back.

Moreover, since the air used for mechanical holding | grip is discharge | released to air | atmosphere, there exists a problem that air consumption increases.
In the apparatus disclosed in Patent Document 6, the acceleration pipe attached to the main nozzle for weft insertion is divided into two parts, and the weft holding lever is pressed against a cradle that connects the two divided acceleration pipes to perform the weft holding. It is like that. For this reason, since there is a large space open to the atmosphere between the two divided acceleration tubes, a part of the weft insertion air leaks from this space. This has a problem in that the weft propulsion force is reduced compared to the main nozzle for weft insertion provided with an undivided accelerating tube, resulting in an increase in air consumption.

  An object of the present invention is to enable effective use of air used for mechanical weft gripping for stabilizing weft insertion, targeting a weft gripping device that uses air pressure for mechanical weft gripping.

  The present invention provides a gripping mechanism for mechanically gripping the weft by injecting the weft from the weft insertion main nozzle by jetting the weft insertion air of the main nozzle for weft insertion provided with an acceleration pipe. In the invention of claim 1, the gripping mechanism includes a pressure introduction chamber for introducing gripping air, and finely jets the weft yarn inside the acceleration tube. A fine injection passage to be actuated is provided between the pressure introduction chamber and the inside of the acceleration pipe, a supply state for supplying gripping air to the pressure introduction chamber, and a grip for the pressure introduction chamber A first gripping air supply switching means that is switched to a supply stop state in which the supply of operating air is stopped is provided, a discharge state in which the gripping air in the pressure introduction chamber is discharged to the fine injection passage, and the pressure A second gripping air supply switching means that is switched to a discharge stop state for stopping the discharge of gripping air in the entrance room is provided, and the gripping mechanism is configured such that the first gripping air supply switching means is in the supply state. And the second gripping air supply switching means grips the weft when the discharge is stopped, and the gripping mechanism is configured such that the first gripping air supply switching means is in the supply stop state and the second gripping air supply. When the switching means is in the discharged state, the weft is released.

  The gripping air used to grip the weft mechanically is discharged into the accelerating tube when releasing the weft and so that the fine wetting can be applied to the weft in the acceleration tube. It is possible to effectively utilize the air used in the step of giving a fine injection action to the weft yarn immediately before weft insertion. Such use eliminates loosening of the weft in the weft insertion main nozzle immediately before weft insertion, and contributes to achieving stable weft insertion.

  In a preferred example, the weft insertion air is supplied to the weft insertion main nozzle via an opening / closing valve, and the fine injection passage connects the opening / closing valve and the weft insertion main nozzle. A discharge passage that joins the passage is provided, and a check valve that prevents backflow of weft insertion air in the discharge passage is provided in the discharge passage.

The configuration in which the weft insertion air is prevented from flowing back to the gripping mechanism side eliminates waste of the weft insertion air and contributes to achieving stable weft insertion.
In a preferred example, the fine injection passage is directly connected to the inside of the acceleration tube, and a part of the fine injection passage is an oblique passage extending from the outer periphery to the inner periphery of the acceleration tube, The oblique passage has a shape that extends in the weft insertion direction from the outer periphery to the inner periphery of the acceleration tube.

  Since the gripping air is discharged into the accelerating pipe from a location different from the weft insertion air supply location in the weft insertion main nozzle, a check valve is not required. Further, the discharge of the gripping air from the oblique passage can cause fine injection to act on the wefts in the main nozzle for weft insertion, so that weft insertion failure is prevented and stable weft insertion is achieved. Further, air discharge from the oblique passage brings an ejector effect and sucks air from outside the main weft insertion nozzle into the weft passage inside the main weft insertion nozzle, so that the weft propulsion force is increased.

In a preferred example, the gripping air in the pressure introducing chamber is discharged into the acceleration pipe before the weft insertion starts.
The configuration in which the gripping air is discharged into the accelerating tube before the weft insertion starts, and the weft thread in the main nozzle for weft insertion immediately before the weft insertion is eliminated, contributing to the achievement of stable weft insertion.

  In a preferred example, when the rotation speed of the loom is N rpm, the gripping air in the pressure introduction chamber is about 24 ° × N rpm / 800 rpm to 72 ° × N rpm / 800 rpm before the weaving start time. Then, the discharge of the gripping air from the pressure introduction chamber and the injection of the weft insertion air are continuously performed.

  The loom rotation speed Nrpm here is the rotation speed per minute. Since weft injection is performed after the weft is released from the gripping action of the gripping member, weft insertion can be performed in a stable state without loosening of the weft.

  In a preferred example, the gripping mechanism includes a gripping member that presses the weft against an inner peripheral wall surface of the acceleration tube, and the gripping member is configured to receive the gripping air when the gripping air is supplied to the pressure introduction chamber. It can be pressed against the peripheral wall surface.

  The gripping member grips the weft thread in the weft insertion main nozzle by pressing it against the inner peripheral wall surface of the acceleration tube. In the configuration in which the weft is pressed against the inner peripheral wall surface, the weft insertion air is not leaked unnecessarily as in Patent Document 6 in which the acceleration tube is divided into two.

  In a preferred example, the fine injection passage is directly connected to the inside of the acceleration tube, and a part of the fine injection passage is a through passage extending from the outer periphery to the inner periphery of the acceleration tube, The penetrating path is directed to the gripping member, and the gripping air discharged from the penetrating path into the accelerating pipe biases the gripping member in a direction to release the weft.

Since the gripping member is biased in the direction of releasing the weft by discharging the gripping air into the acceleration tube, the responsiveness of the gripping member when releasing the weft is improved.
In a preferred example, the through passage has a shape that extends in the weft insertion direction from the outer periphery to the inner periphery of the acceleration tube.

The discharge of gripping air from the through passage contributes to prevention of weft loosening in the main nozzle for weft insertion.
In a preferred example, the first gripping air supply switching means and the second gripping air supply switching means include a three-port valve type control valve, and the control valve is used for gripping the pressure introduction chamber. A first switching state that takes the supply state for supplying air and the discharge stop state for stopping the discharge of gripping air from the pressure introduction chamber; and the supply of gripping air to the pressure introduction chamber is stopped. It is switched between a supply stop state and a second switching state in which the holding air is discharged from the pressure introduction chamber.

The three-port valve is convenient as a component of the first gripping air supply switching means and the second gripping air supply switching means.
In a preferred example, the gripping mechanism includes a gripping member that presses the weft against an inner peripheral wall surface of the acceleration tube, and a back pressure chamber that is partitioned from the pressure introduction chamber by the gripping member. The air supply switching means and the second gripping air supply switching means include a five-port valve type control valve, and the control valve supplies the gripping air to the pressure introducing chamber, A gripping state in which the discharge stop state for stopping the discharge of the gripping air from the pressure introduction chamber and a back pressure release state in which release of the release air from the back pressure chamber is permitted; and the pressure introduction chamber Gripping that takes the supply stop state in which the supply of gripping air is stopped, the discharge state in which gripping air is discharged from the pressure introduction chamber, and the back pressure supply state in which release air is supplied to the back pressure chamber Switch to the released state.

The configuration using the release air to release the weft from the gripping action shortens the response time of the gripping member and contributes to the speeding up of the loom.
In a preferred example, the effective cross-sectional area of the control valve ^is set to 1 mm 2 to 3 mm ^2.

  In such a setting, the fine injection pressure when the gripping air is discharged into the weft insertion main nozzle is maintained at an appropriate pressure that does not cause the weft breakage.

  The present invention is directed to a weft gripping device that uses air pressure for mechanical weft gripping, and has an excellent effect that air used for mechanical weft gripping can be effectively used for weft insertion stabilization.

1 is a perspective view showing a first embodiment embodying the present invention, wherein (a) shows a main nozzle for weft insertion and a weft gripper. FIG. (B) is sectional drawing of a weft gripper. (C) is a partial expanded sectional view of an acceleration tube. Schematic diagram of the entire jet loom. (A) is sectional drawing and air piping figure of the weft gripping apparatus which show a weft gripping state. (B) is a cross-sectional view and an air piping diagram of the weft gripping device showing a weft released state. Sectional drawing and air piping figure of the weft holding device which show a weft insertion state. The graph which shows the pressure change in the main nozzle for weft insertion. (A) is a graph which shows the pressure change in the main nozzle for weft insertion. (B) is a graph which shows the pressure change in the main nozzle for weft insertion at the time of the conventional fine injection use. (A) is a graph which shows the example of a measurement of weft tip passage time. (B) is a graph showing a measurement example of the weft tip passing time when the gripping air is released into the atmosphere. The graph which shows the relationship between the effective cross-sectional area of a three-port valve, and the pressure in the main nozzle for weft insertion. The 2nd Embodiment is shown, (a) is sectional drawing and air piping figure of the weft holding device which shows a weft holding state. (B) is a cross-sectional view and an air piping diagram of the weft gripping device showing a weft released state. Sectional drawing and air piping figure which show the weft release state of the weft gripping apparatus which shows 3rd Embodiment. Sectional drawing and air piping figure which show the weft release state of the weft holding device which shows 4th Embodiment.

Hereinafter, a first embodiment in which the present invention is embodied in a two-color weft insertion type air jet loom will be described with reference to FIGS.
As shown in FIG. 1A, the sley 11 is supported via a sley sword 13 on a rocking shaft 12 that reciprocally rotates by obtaining a driving force from a loom driving motor (not shown). Weft insertion main nozzles 14 and 15 are fixed on the sley 11 via the support base 10, and a ridge 16 and a plurality of auxiliary nozzles 17 are fixed on the slay 11. The sley 11, the weft insertion main nozzles 14 and 15, the eaves 16, and the plurality of auxiliary nozzles 17 oscillate around the locking shaft 12 in the front-rear direction of the loom by the reciprocating rotation of the locking shaft 12.

A pair of tandem nozzles 18 and 19 are fixedly installed on a side frame (not shown) of the loom. Reference numerals 20 and 21 denote winding type weft length measuring and storage devices.
As shown in FIG. 2, the wefts Y <b> 1 and Y <b> 2 are wound around the thread winding surface 23 by the rotation of the thread winding tube 22. The weft drawing and unwinding from the bobbin winding surface 23 is controlled by the operation of the locking pin 241 of the electromagnetic solenoid 24. Excitation demagnetization of the electromagnetic solenoid 24 is performed by command control of the control computer C, and the control computer C controls excitation and demagnetization of the electromagnetic solenoid 24 based on the weft unwinding detection information from the weft unwinding detector 25. The weft unwinding detector 25 detects the unwinding of the wound yarn on the thread winding surface 23. When a predetermined number of turns of the wound yarn on the yarn winding surface 23 is unwound, the control computer C demagnetizes the electromagnetic solenoid 24 so as to protrude the locking pin 241 and prevent the weft drawing unwinding.

  The wefts Y1 and Y2 measured and stored by the weft length measuring and storing devices 20 and 21 are passed through the tandem nozzles 18 and 19, and the weft Y1 and Y2 passed through the tandem nozzles 18 and 19 are the main nozzle 14 for weft insertion. , 15 are separately passed through the acceleration tubes 26, 27. The acceleration pipes 26 and 27 of the weft insertion main nozzles 14 and 15 are directed to a weft guide passage 162 formed on the front surface of the wings 161 of the heel 16. The weft Y1 is inserted into the opening of the warp T by air injection from the acceleration tube 26, and the weft Y2 is inserted into the opening of the warp T by air injection from the acceleration tube 27.

Only one of the wefts Y1 and Y2 is inserted in one weft insertion according to a preset weft insertion order pattern.
The wefts Y1 and Y2 inserted into the opening of the warp T are pulled in the weft guide passage 162 by the relay injection of the plurality of auxiliary nozzles 17. The weft thread inserted in the weft [Y1 in the example shown in FIG. 1 (a)] is beaten on the pre-weaving W1 of the woven fabric W by the beating operation of the reed 16.

  When the weft insertion is performed satisfactorily, the wefts Y1 and Y2 are detected by the weft detector 28 within a predetermined loom rotation angle range. The weft presence / absence detection signal from the weft detector 28 is input to the control computer C, and the control computer C selects either continuation or stop of the loom operation based on the weft presence / absence detection signal.

  The weft insertion main nozzle 14 is connected to an air supply tank 31 via a weft insertion air supply tube 29 serving as a weft insertion air passage and an electromagnetic on-off valve 30, and the weft insertion main nozzle 15 is It is connected to an air supply tank 34 via a weft insertion air supply tube 32 and an electromagnetic on-off valve 33 as an air passage. The tandem nozzle 18 is connected to an air supply tank 37 via a weft insertion air supply tube 35 and an electromagnetic opening / closing valve 36, and the tandem nozzle 19 is connected via a weft insertion air supply tube 38 and an electromagnetic opening / closing valve 39. An air supply tank 40 is connected. The auxiliary nozzle 17 is connected to the air supply tank 43 through the air supply tube 41 and the electromagnetic opening / closing valve 42.

  Excitation / demagnetization control of each electromagnetic on-off valve 30, 33, 36, 39, 42 is performed by a command from the control computer C. The control computer C controls the excitation / demagnetization of the electromagnetic on-off valves 30, 33, 36, 39, and 42 based on the loom rotation angle detection information obtained from the rotary encoder E for detecting the loom rotation angle. Each electromagnetic on-off valve 30, 33, 36, 39, 42 is opened (air supply state) by excitation and closed (air supply stop state) by demagnetization.

  As shown in FIG. 1A, a weft gripper 44 is attached to the tip of the acceleration pipes 26 and 27 of the main nozzles 14 and 15 for weft insertion. The weft gripper 44 is supported by a part of the support 10.

  As shown in FIG. 1B, the weft gripper 44 includes a mounting block 45 attached to the acceleration tubes 26 and 27 so as to keep the acceleration tubes 26 and 27 horizontal, and a pair of housings accommodated in the mounting block 45. Piston housings 46 and 47 and pistons 48 and 49 slidably accommodated in the respective piston housings 46 and 47 are provided. Guide rods 50 and 51 project from one end surfaces of the pistons 48 and 49, and grip rods 52 and 53 project from the other end surfaces of the pistons 48 and 49. The pistons 48 and 49 divide the piston housings 46 and 47 into pressure introducing chambers 54 and 55 and spring accommodating chambers 56 and 57, and compression springs 58 and 59 are accommodated in the spring accommodating chambers 56 and 57. Yes. In this embodiment, the piston housings 46 and 47 are made of gun metal, and the pistons 48 and 49 are made of polyimide resin that is lightweight and highly durable.

The piston housings 46 and 47, the pistons 48 and 49, the gripping rods 52 and 53, and the pressure introducing chambers 54 and 55 constitute a gripping mechanism for gripping the wefts Y1 and Y2.
The inlets 601 and 611 are provided in the lids 60 and 61 constituting the piston housings 46 and 47 so as to open on the outer surfaces of the lids 60 and 61, and the guide holes 602 and 612 are formed on the inner surfaces of the lids 60 and 61. It is provided to open. The guide holes 602 and 612 communicate with the introduction ports 601 and 611, and the diameters of the guide holes 602 and 612 are larger than the diameters of the introduction ports 601 and 611. The guide rods 50 and 51 are slidably fitted in the guide holes 602 and 612. The guide rods 50 and 51 can contact the step between the guide holes 602 and 612 and the introduction ports 601 and 611. Communication passages 501 and 511 are formed in the guide rods 50 and 51. The communication passages 501 and 511 communicate the pressure introduction chambers 54 and 55 with the introduction ports 601 and 611.

A pair of through holes 452 and 453 are provided through the bottom wall 451 of the mounting block 45, and the acceleration tubes 26 and 27 are passed through the through holes 452 and 453.
As shown in FIG. 1 (c), the entrance and exit holes 261 and 271 are formed in the acceleration tubes 26 and 27 so as to penetrate the tube walls of the acceleration tubes 26 and 27, and the inner peripheral wall surfaces of the acceleration tubes 26 and 27. The recesses 262 and 272 are formed in the recesses 260 and 270 so as to face the entrance / exit holes 261 and 271. The distal end surface of the gripping rod 52 enters the tube of the acceleration tube 26 from the entrance / exit hole 261 and can come into surface contact with the bottom of the recess 262, and the distal end surface of the grasping rod 53 enters the tube of the acceleration tube 27 from the access port 271. The surface can be brought into contact with the bottom of the recess 272 by entering. The bottoms of the recesses 262 and 272 are flat surfaces, and the tip surfaces of the grip rods 52 and 53 are planes parallel to the bottoms of the recesses 262 and 272.

  As shown in FIGS. 1B and 2, the piston housing 46 includes a common air tube 62 </ b> B connected to an inlet 601 [see FIG. 1B], an electromagnetic three-port valve 63 as a control valve, and a gripping member. It is connected to an air supply tank 64 via an air supply tube 62A. The piston housing 47 is connected to an air supply tank 67 via a common air tube 65B connected to an inlet 611 [see FIG. 1B], an electromagnetic three-port valve 66 as a control valve, and a gripping air supply tube 65A. Has been.

  Excitation demagnetization control of the electromagnetic three-port valves 63 and 66 is performed by a command from the control computer C. The control computer C controls the excitation and demagnetization of the electromagnetic three-port valves 63 and 66 based on the loom rotation angle detection information obtained from the rotary encoder E for detecting the loom rotation angle. The electromagnetic three-port valves 63 and 66 are opened (air supply state) by demagnetization and are closed (air supply stop state) by excitation.

  The electromagnetic three-port valve 63 is joined and connected in the middle of the weft insertion air supply tube 29 via a discharge air supply tube 68 and a check valve 69. The check valve 69 prevents a back flow from the weft insertion air supply tube 29 side to the electromagnetic three-port valve 63 side. The electromagnetic three-port valve 66 is joined and connected in the middle of the weft insertion air supply tube 32 via a discharge air supply tube 70 and a check valve 71. The check valve 71 prevents a back flow from the weft insertion air supply tube 32 side to the electromagnetic three-port valve 66 side.

  When the electromagnetic three-port valve 63 is in a demagnetized state, the pressure air in the air supply tank 64 moves from the pressure introducing chamber 54 side to the spring accommodating chamber 56 side against the spring force of the compression spring 58 acting on the piston 48. The pressure is supplied to the pressure introducing chamber 54. When the electromagnetic three-port valve 63 is excited, the piston 48 is returned from the spring accommodating chamber 56 side to the pressure introducing chamber 54 side by the spring force of the compression spring 58, and the pressure air in the pressure introducing chamber 54 is discharged from the common air tube 62B. The air is supplied to the weft insertion air supply tube 29 through the air supply tube 68 and the check valve 69. The common air tube 62B and the discharge air supply tube 68 constitute a discharge passage 79 (see FIGS. 1A and 3) for discharging the gripping air in the pressure introduction chamber 54 to the acceleration tube 26.

  When the electromagnetic three-port valve 66 is demagnetized, the piston 49 is moved from the pressure introducing chamber 55 side to the spring accommodating chamber 57 side against the spring force of the compression spring 59 acting on the piston 49 by the pressure air in the air supply tank 67. The pressure is supplied to the pressure introducing chamber 55. When the electromagnetic three-port valve 66 is in an excited state, the piston 49 is returned from the spring accommodating chamber 57 side to the pressure introducing chamber 55 side by the spring force of the compression spring 59, and the pressure air in the pressure introducing chamber 55 is discharged to the common air tube 65B. The air is supplied to the weft insertion air supply tube 32 via the air supply tube 70 and the check valve 71. The common air tube 65 </ b> B and the discharge air supply tube 70 constitute a discharge passage 80 (see FIG. 1A) for discharging the gripping air in the pressure introduction chamber 55 to the acceleration tube 27.

  The control computer C and the electromagnetic three-port valves 63 and 66 are in a supply state in which gripping air is supplied to the pressure introduction chambers 54 and 55, and a supply in which supply of the gripping air to the pressure introduction chambers 54 and 55 is stopped. The first gripping air supply switching means that is switched to the stop state is configured.

  Further, the control computer C and the electromagnetic three-port valves 63 and 66 are in a discharge state in which the gripping air in the pressure introduction chambers 54 and 55 is discharged into the acceleration pipes 26 and 27, and for gripping in the pressure introduction chambers 54 and 55. The second gripping air supply switching means is configured to be switched to a discharge stop state in which the discharge of air is stopped.

  The demagnetization state of the electromagnetic three-port valves 63 and 66 corresponds to the supply state and the discharge stop state, and the excitation state of the electromagnetic three-port valves 63 and 66 corresponds to the supply stop state and the discharge state. Yes.

Next, a series of operations from gripping the weft Y1 on the weft insertion main nozzle 14 side to inserting the weft will be described with reference to FIGS. 3 (a), 3 (b) and FIG.
FIG. 3A shows a demagnetized state of the electromagnetic three-port valve 63. When the electromagnetic three-port valve 63 is demagnetized, the pressure air in the air supply tank 64 is moved from the pressure introduction chamber 54 side through the gripping air supply tube 62A, the electromagnetic three-port valve 63 and the common air tube 62B. While being moved toward the spring accommodating chamber 56, the pressure introduction chamber 54 is supplied, and the weft Y 1 is gripped between the tip of the grip rod 52 and the bottom of the recess 262 of the acceleration tube 26.

  When the timing for releasing the weft Y1 comes, the electromagnetic three-port valve 63 is excited as shown in FIG. When the electromagnetic three-port valve 63 is excited, the piston 48 is returned from the spring accommodating chamber 56 side to the pressure introducing chamber 54 side by the spring force of the compression spring 58, and the pressure air in the pressure introducing chamber 54 is shared by the common air tube 62B, The air is discharged into the air passage 141 in the weft insertion main nozzle 14 through the electromagnetic three-port valve 63, the discharge air supply tube 68, the check valve 69 and the weft insertion air supply tube 29. The pressure in the pressure introducing chamber 54 gradually decreases, the gripping rod 52 moves away from the bottom of the recess 262, and the weft Y1 is released from the gripping action of the gripping rod 52.

  The pressure air in the pressure introducing chamber 54 (gripping air) passes through the discharge passage 79, the weft insertion air supply tube 29, and the air passage 141 around the thread guide 140 in the weft insertion main nozzle 14, and the acceleration pipe 26. It is discharged inside. That is, the air discharged from the weft insertion air supply tube 29 to the air passage 141 is finely injected and acts on the weft Y1 in the main nozzle 14 for weft insertion. As a result, the yarn posture of the weft Y1 in the accelerating tube 26 is kept straight.

  The discharge passage 79, the weft insertion air supply tube 29, and the air passage 141 are finely provided between the pressure introducing chamber 54 and the inside of the acceleration pipe 26 so that the fine injection is applied to the weft Y1 inside the acceleration pipe 26. An injection passage is configured.

  Similarly, the air passage (not shown) in the discharge passage 80, the weft insertion air supply tube 32, and the weft insertion main nozzle 15 has a pressure introduction chamber so that fine injection is applied to the weft Y2 inside the acceleration pipe 27. A fine injection passage provided between 55 and the inside of the acceleration tube 27 is formed.

  At the weft insertion timing, as shown in FIG. 4, the electromagnetic on-off valve 30 is excited, and the weft insertion pressure air in the air supply tank 31 (see FIG. 2) is supplied to the electromagnetic on-off valve 30 and the weft insertion air supply tube 29. To the main nozzle 14 for weft insertion. The weft Y1 released from the gripping action of the gripping rod 52 is ejected from the acceleration tube 26 by the supply of weft insertion pressure air into the weft insertion main nozzle 14. Since a check valve 69 is provided in the middle of the discharge air supply tube 68 joined and connected to the weft insertion air supply tube 29, a part of the weft insertion pressure air flowing through the weft insertion air supply tube 29 is There is no supply to the pressure introduction chamber 54 side. In the state of FIG. 4, the grip rod 52 is retracted from the inside of the accelerating tube 26, and smooth weft insertion is possible.

  A curve P1 in the graph of FIG. 6A shows a change in the injection pressure at the main nozzle 14 for weft insertion, and a curve P2 shows a change in the injection pressure at the main nozzle 15 for weft insertion. Curve portions P11 and P21, which are a part of the curves P1 and P2, change in pressure due to the discharge of gripping air from the pressure introduction chamber 54 into the weft insertion main nozzle 14, that is, fine injection into the weft Y1. It represents the pressure change that acts. This fine injection period is about 30 ° of the loom rotation angle range immediately before the start of the weft injection.

  A curve D1 in the graph of FIG. 6B shows a change in the injection pressure in the conventional weft insertion main nozzle 14 without the electromagnetic three-port valve 63 and the weft gripper 44, and a curve D2 indicates the electromagnetic three-port valve 66 and The change of the injection pressure in the main nozzle 15 for the conventional weft insertion without the weft gripper 44 is shown. Curve portions D11 and D21, which are a part of the curves D1 and D2, represent pressure changes when conventional fine injection air is supplied to the main nozzles 14 and 15 for weft insertion.

The fine injection period in the present embodiment indicated by the curved parts P11 and P21 is much shorter than the conventional fine injection period indicated by the curved parts D11 and D21.
Curves F1 and F2 in the graph of FIG. 5 show changes in the injection pressure in the main weft insertion nozzle 14 when the gripping air in the pressure introduction chamber 54 is discharged to the main insertion nozzle 14. The effective sectional area of the electromagnetic three-port valve 63 is 2 mm ² . A curve F1 is a pressure change when the maximum pressure in the pressure introduction chamber 54 is set to 0.3 MPa, and a curve F2 is a pressure change when the maximum pressure in the pressure introduction chamber 54 is set to 0.5 MPa. is there. The loom rotational speed is 800 rpm in both cases of the curves F1 and F2. Curves F1 and F2 indicate that the effective injection period of the fine injection due to the discharge from the pressure introducing chamber 54 into the weft insertion main nozzle 14 varies by about 5 ms to 15 ms depending on how the maximum pressure is set. 5 ms to 15 ms is 24 ° to 72 ° in terms of the loom rotation angle. In the present embodiment, the gripping air in the pressure introduction chamber 54 starts to be discharged from the pressure introduction chamber 54 at any one of the loom rotation angles 24 ° to 72 ° before the weft insertion start.

  A curve G in the graph of FIG. 7A represents the result of examining the variation of the weft flying time (weft tip passing time) at the position where the weft Y1 flew 120 mm immediately after the start of weft insertion in this embodiment. The curve L in the graph of FIG. 7 (b) indicates that the weft Y1 immediately after the start of weft insertion in the conventional device disclosed in Patent Documents 5 and 6 (device that releases air without using the gripping air for fine injection). The result of having investigated about the dispersion | variation in the weft flying time in the position which flew 120 mm is represented. Curves G and L indicate that the variation in the weft flying time is smaller in the present embodiment in which the gripping air is used for fine injection than in the conventional device that releases the gripping air to the atmosphere.

A curve K in the graph of FIG. 8 represents the relationship between the effective sectional area of the electromagnetic three-port valve 63 and the fine injection pressure in the main nozzle 14 for weft insertion. In the present embodiment, the effective cross-sectional area of the solenoid three-port valve 63 ^is set to 1 mm 2 to 3 mm ^2.

In the first embodiment, the following effects can be obtained.
(1) The gripping air in the pressure introducing chambers 54, 55 is discharged into the acceleration pipes 26, 27 when releasing the weft yarn and immediately before weft insertion so as to give a fine injection action to the weft yarns Y1, Y2. The gripping air used for mechanically gripping Y1 and Y2 can be effectively used to achieve stable weft insertion without being wasted.

(2) The configuration in which the weft insertion air is prevented from flowing back to the pressure introducing chambers 54 and 55 can prevent the weft insertion air from being wasted and contribute to the achievement of stable weft insertion.
(3) As is apparent from the graphs of FIGS. 6A and 6B, the configuration in which the gripping air in the pressure introduction chambers 54 and 55 is used for fine injection shortens the period of fine injection and consumes air. Contributes to reducing the amount. Conventionally, the fine injection period per main weft insertion nozzle becomes longer as the weft type increases, but in this embodiment, the fine injection period per main weft insertion nozzle even if the weft type increases. There is no need to lengthen the air consumption, and the air consumption can be greatly reduced.

  (4) As is apparent from the graphs of FIGS. 7A and 7B, in this embodiment, the variation in the weft tip passage time is less than in the case where the gripping air is released into the atmosphere without being used for fine injection. Reduce significantly. Such a reduction in the variation in the weft tip passing time contributes to stabilizing the weft insertion. The configuration in which the gripping air is used for fine injection is effective for stabilizing the weft insertion in terms of the weft flight.

(5) When the gripping air discharged from the pressure introducing chamber 54 is used for fine injection, it is necessary to keep the fine injection pressure appropriately. In the case of a spun yarn, an appropriate fine spray pressure at the weft insertion main nozzle 14 is 0.01 MPa to 0.03 MPa. Curve K shows that it is desirable that the effective cross-sectional area of the electromagnetic three-port valve 63 to ^{1 mm} 2 to 3 mm ^2. In other words, in the present embodiment sets the effective area of the electromagnetic three-port valve 63 to 1 mm ² to 3 mm ^2, the micro-injection pressure is weft breakage at the time of discharging the gripping air into the weft insertion for the main nozzles 14, 15 It is kept at an appropriate pressure that does not occur.

  (6) Since the wefts Y1 and Y2 are gripped between the distal end surfaces of the gripping rods 52 and 53 and the inner peripheral wall surfaces 260 and 270 of the acceleration tubes 26 and 27, the gripped portions of the wefts Y1 and Y2 are deformed. There is a fear. However, since the grip rods 52 and 53 grip the wefts Y1 and Y2 on the distal end side of the acceleration tubes 26 and 27, the gripping portions of the wefts Y1 and Y2 are removed as discard ears. For this reason, the gripping portions of the wefts Y1 and Y2 are not woven into the woven fabric W, and the quality of the fabric does not deteriorate.

  (7) In this embodiment using a mechanical gripping device that grips the wefts Y1, Y2 between the gripping rods 52, 53 and the inner peripheral wall surfaces 260, 270 of the acceleration tubes 26, 27, disclosed in Patent Document 4 Compared with the method in which the weft is pressed against the fixed wall by such an air flow and held, the reliability of the weft is significantly higher. In the configuration in which the wefts Y1 and Y2 are pressed against the inner peripheral wall surfaces 260 and 270 (recesses 262 and 272), the weft insertion air is not leaked as in the case of Patent Document 6 in which the acceleration tube is divided into two.

(8) The electromagnetic three-port valves 63 and 66 are simple as components of the first gripping air supply switching means and the second gripping air supply switching means.
(9) As shown in FIG. 5, the effective injection period of fine injection by discharge from the pressure introduction chamber 54 into the weft insertion main nozzle 14 varies from 24 ° to depending on how the maximum pressure in the pressure introduction chamber 54 is set. It changes about 72 °. Therefore, when the loom rotational speed is 800 rpm, it is desirable to start discharging the gripping air in the pressure introducing chamber 54 from the loom rotation angle of 24 ° to 72 ° before the weft insertion start.

  Generally, the loom rotational speed is used in a range of 700 rpm to 1000 rpm, and the range of the gripping air discharge start by the loom rotational angle display changes according to the change of the loom rotational speed. For example, if the loom rotational speed is 700 rpm, the gripping air discharge start range is 24 ° × 700 rpm / 800 rpm = 21 ° to 72 ° × 700 rpm / 800 rpm = 63 °. If the loom rotational speed is 700 rpm, the gripping air discharge start range is 24 ° × 1000 rpm / 800 rpm = 30 ° to 72 ° × 1000 rpm / 800 rpm = 90 °.

  Therefore, when the loom rotational speed is N rpm, the discharge of the gripping air in the pressure introduction chamber 54 is started from the front of the weft insertion from the front of the loom rotation angle of 24 ° × N / 800 to 72 ° × N / 800. desirable.

Next, a second embodiment of FIGS. 9A and 9B will be described. The same reference numerals are used for the same components as those in the first embodiment, and detailed description thereof is omitted.
In the second embodiment, electromagnetic five-port valves 72 and 73 are used instead of the electromagnetic three-port valve. The electromagnetic five-port valve 72 is for the weft insertion main nozzle 14, and the electromagnetic five-port valve 73 is for the weft insertion main nozzle 15. The electromagnetic five-port valves 72 and 73 are subjected to excitation / demagnetization control by the control computer C (see FIG. 2).

  The pistons 48A and 49A of the weft gripper 44A partition the piston housings 46 and 47 into pressure introducing chambers 54 and 55 and back pressure chambers 74 and 75, respectively. The pressure introducing chambers 54 and 55 are connected to the electromagnetic five-port valves 72 and 73 via the gripping air supply tubes 62A and 65A, and the back pressure chambers 74 and 75 are electromagnetically connected via the back pressure tubes 76 and 77. Connected to five-port valves 72 and 73.

  FIG. 9A shows the demagnetization state of the electromagnetic five-port valves 72 and 73. When the electromagnetic five-port valves 72 and 73 are demagnetized, the pressure air is introduced into the pistons 48A and 49A via the gripping air supply tubes 62A and 65A, the electromagnetic five-port valves 72 and 73, and the common air tubes 62B and 65B. While being moved from the chambers 54, 55 side to the back pressure chambers 74, 75 side, the pressure introduction chamber 54 is supplied, and the wefts Y 1, Y 2 are between the tips of the grip rods 52, 53 and the bottom of the recess 262 of the acceleration tube 26. Grasped. The air in the back pressure chambers 74 and 75 is released to the atmosphere via the back pressure tubes 76 and 77 and the electromagnetic five-port valves 72 and 73.

  When the timing for releasing the wefts Y1 and Y2 comes, the electromagnetic five-port valves 72 and 73 are excited as shown in FIG. 9B. When the electromagnetic five-port valves 72 and 73 are excited, the pressure air is supplied to the back pressure chambers 74 and 75 via the common air tubes 62B and 65B, the electromagnetic five-port valves 72 and 73 and the back pressure tubes 76 and 77. The The pistons 48A and 49A are returned to the pressure introduction chambers 54 and 55 from the back pressure chambers 74 and 75 by the back pressure in the back pressure chambers 74 and 75, and the pressure air in the pressure introduction chambers 54 and 55 is returned to the common air tube. 62B, 65B, discharge air supply tubes 68, 70, check valves 69, 71 and weft insertion air supply tubes 29, 32 are discharged into the weft insertion main nozzles 14, 15. The pressure in the pressure introducing chambers 54 and 55 gradually decreases, the gripping rods 52 and 53 are separated from the inner peripheral wall surfaces 260 and 270, and the wefts Y1 and Y2 are released from the gripping action of the gripping rods 52 and 53. Is done.

  The control computer C and the electromagnetic five-port valves 72 and 73 are in a supply state in which gripping air is supplied to the pressure introduction chambers 54 and 55, and a supply in which supply of the gripping air to the pressure introduction chambers 54 and 55 is stopped. The first gripping air supply switching means that is switched to the stop state is configured.

  Further, the control computer C and the electromagnetic five-port valves 72 and 73 are in a discharge state in which the gripping air in the pressure introduction chambers 54 and 55 is discharged into the acceleration pipes 26 and 27 and The second gripping air supply switching means is configured to be switched to a discharge stop state in which the discharge of air is stopped.

  The demagnetization state of the electromagnetic five-port valves 72 and 73 corresponds to the supply state and the discharge stop state, and the excitation state of the electromagnetic five-port valves 72 and 73 corresponds to the supply stop state and the discharge state. Yes.

  In this embodiment, the concave portions 262 and 272 in the first embodiment are not provided, and the distal end surfaces of the grip rods 52 and 53 are formed in a curved shape so as to be surface-bondable to the curved surfaces of the inner peripheral wall surfaces 260 and 270. .

  Air discharge from the weft insertion air supply tubes 29, 32 into the weft insertion main nozzles 14, 15 acts as a fine injection on the wefts Y1, Y2 in the weft insertion main nozzles 14, 15. Thereby, the yarn postures of the wefts Y1, Y2 in the acceleration tubes 26, 27 are kept straight.

  In the second embodiment, the same effects as the items (1) to (7) in the first embodiment can be obtained. In addition, since pressure air is used for both gripping and releasing the weft, the response time of the gripping rods 52 and 53 can be made shorter than in the first embodiment. Further, since the compression spring is not used for releasing the weft, maintenance is reduced.

Next, a third embodiment of FIG. 10 will be described. The same reference numerals are used for the same components as those in the first embodiment, and detailed description thereof is omitted.
In the third embodiment, a passage forming ring 78 is attached to the base of the acceleration tubes 26 and 27. An introduction port 781 is formed in the passage forming ring 78, and an annular passage 782 is formed between the passage forming ring 78 and the outer peripheral surfaces of the acceleration tubes 26 and 27. Discharge air supply tubes 68 and 70 are connected to the introduction port 781. A plurality of oblique passages 263, 273 are formed on the outer peripheral surfaces of the acceleration tubes 26, 27 surrounded by the annular passage 782 so as to pass through the tube walls of the acceleration tubes 26, 27 and open into the tubes. The oblique passages 263 and 273 have a shape that extends in the weft insertion direction R from the outer peripheral surface of the acceleration tubes 26 and 27 toward the inner peripheral surface.

  The gripping air in the pressure introducing chambers 54 and 55 passes through the common air tubes 62B and 65B, the electromagnetic three-port valves 63 and 66, the discharge air supply tubes 68 and 70, the annular passage 782, and the oblique passages 263 and 273. Then, it is discharged into the acceleration tubes 26 and 27. The discharge air supply tubes 68 and 70, the annular passage 782, and the oblique passages 263 and 273 are arranged in the pressure introduction chambers 54 and 55 and the acceleration pipe 26 so that fine injection is applied to the wefts Y 1 and Y 2 inside the acceleration pipes 26 and 27. , 27 constitutes a fine injection passage.

In the third embodiment, since the discharge air supply tubes 68 and 70 do not merge with the weft insertion air supply tubes 29 and 32, the check valves 69 and 71 in the first embodiment are not necessary.
The discharge of the gripping air from the oblique passages 263 and 273 into the acceleration pipes 26 and 27 can cause the fine injection to act on the wefts Y1 and Y2 in the acceleration pipes 26 and 27, thereby preventing the weft insertion failure and stabilizing. Weft insertion is achieved. Further, the discharge of air from the oblique passages 263 and 273 brings about an ejector effect and sucks air from outside the weft insertion main nozzles 14 and 15 into the weft passages in the weft insertion main nozzles 14 and 15. Power increases.

Next, a fourth embodiment of FIG. 11 will be described. The same reference numerals are used for the same components as those in the first embodiment, and detailed description thereof is omitted.
In the fourth embodiment, penetrating passages 264 and 274 are opened to the inner peripheral wall surfaces 260 and 270 at positions facing the distal end surfaces of the grip rods 52 and 53 on the outer peripheral surface on the distal end side of the acceleration tubes 26 and 27. It is penetrating. In the bottom wall 451 of the mounting block 45, introduction ports 454 and 455 are formed so as to communicate with the through passages 264 and 274. Discharge air supply tubes 68 and 70 are connected to the introduction ports 454 and 455. The through passages 264 and 274 have a shape that extends in the weft insertion direction R from the outer peripheral surface of the acceleration tubes 26 and 27 toward the inner peripheral surface. The through passages 264 and 274 are directed to the distal end surfaces of the grip rods 52 and 53.

  The gripping air in the pressure introducing chambers 54 and 55 passes through the common air tubes 62B and 65B, the electromagnetic three-port valves 63 and 66, the discharge air supply tubes 68 and 70, and the through passages 264 and 274, and the acceleration pipe 26 , 27 is discharged. The gripping air discharged into the accelerating tubes 26 and 27 strikes the tip surfaces of the gripping rods 52 and 53, and the gripping rods 52 and 53 are urged away from the opposing inner peripheral wall surfaces 260 and 270. The That is, the grip rods 52 and 53 are biased in the direction of releasing the wefts Y1 and Y2 by the discharge of the gripping air into the acceleration tubes 26 and 27. Therefore, the responsiveness of the grip rods 52 and 53 is enhanced, and the release of the wefts Y1 and Y2 is accelerated. Early release of the wefts Y1, Y2 is effective for stabilizing the weft insertion.

  The gripping air discharged into the acceleration pipes 26 and 27 from the through passages 264 and 274 shaped in the weft insertion direction R from the outer circumference to the inner circumference of the acceleration pipes 26 and 27 causes the wefts Y1 and Y2 to be wefted. The fine injection is pulled in the insertion direction R, and the discharge of the gripping air from the through passages 264, 274 contributes to the prevention of loosening of the wefts Y1, Y2 in the main nozzles 14, 15 for weft insertion.

  The discharge air supply tubes 68 and 70 and the through passages 264 and 274 are arranged inside the pressure introducing chambers 54 and 55 and the acceleration pipes 26 and 27 so that fine injection is applied to the wefts Y1 and Y2 inside the acceleration pipes 26 and 27. A fine injection passage provided between the two.

In the present invention, the following embodiments are also possible.
In the first, third, and fourth embodiments, as an electromagnetic three-port valve, gripping air is supplied to the pressure introduction chambers 54 and 55 by excitation, and the gripping air in the pressure introduction chambers 54 and 55 is discharged by demagnetization. An electromagnetic three-port valve as described above may be used.

○ When the effective sectional area of the electromagnetic three-port valves 63, 66 is larger than 3 mm ² , a throttle valve is provided at the discharge port of the electromagnetic three-port valves 63, 66 (the port to which the discharge air supply tubes 68, 70 are connected) the effective cross-sectional area of the throttle valve may be ^{1 mm} 2 to 3 mm ^2.

  In the fourth embodiment, the through paths 264 and 274 may be oriented in a direction perpendicular to the weft insertion direction R. Also in this case, the responsiveness of the grip rods 52 and 53 is improved.

  A first electromagnetic on-off valve may be used as the first gripping air supply switching means, and a second electromagnetic on-off valve may be used as the second gripping air supply switching means. In this case, the first electromagnetic open / close valve and the pressure introducing chambers 54 and 55 are connected by the first air tube, the gripping air supply tubes 62A and 65A are connected to the first electromagnetic open / close valve, and the second The electromagnetic open / close valve and the pressure introducing chambers 54 and 55 may be connected by the second air tube, and the discharge air supply tubes 68 and 70 may be connected to the second electromagnetic open / close valve. When the first electromagnetic on-off valve is in the open state and the second electromagnetic on-off valve is in the closed state, the gripping air is supplied to the pressure introducing chambers 54 and 55 through the first air tube. When the second electromagnetic on-off valve is in the open state and the first electromagnetic on-off valve is in the closed state, the gripping air in the pressure introduction chambers 54 and 55 is discharged via the second air tube.

The present invention may be applied to a weft gripping device that grips the wefts downstream of the tips of the acceleration tubes 26 and 27.
The present invention may be applied to a weft gripping device that grips the wefts upstream of the acceleration tubes 26 and 27.

The present invention may be applied to a multicolor jet loom in which three or more types of wefts are inserted.
The technical idea that can be grasped from the embodiment described above will be described below.
(A) The weft gripping device in an air jet loom according to claim 10, wherein the gripping air discharged from the pressure introducing chamber is discharged to the atmosphere.

  (B) The weft gripping device in the air jet loom according to any one of claims 1 to 11, wherein the gripping mechanism mechanically grips the weft in the acceleration tube or upstream of the acceleration tube.

  The gripping portion of the weft is not woven into the woven fabric, and the quality of the fabric is not deteriorated.

  14, 15 ... Main nozzle for weft insertion. 26, 27 ... Accelerating tubes. 260, 270 ... inner peripheral wall surface. 263, 273 ... Diagonal passage. 264, 274 ... through passage. 29, 32 ... Weft insertion air supply tubes as weft insertion air passages. 30, 33 ... electromagnetic on-off valve. 52, 53 ... gripping rods as gripping members constituting a gripping mechanism. 54, 55 ... Pressure introducing chambers constituting a gripping mechanism. 63, 64: electromagnetic three-port valve as a control valve constituting the first gripping air supply switching means and the second gripping air supply switching means. 68, 70 ... Discharge air supply tubes constituting a discharge passage. 69, 71: Check valve. 72, 73: Electromagnetic five-port valve as a control valve. 74, 75 ... Back pressure chamber. 79, 80 ... Discharge passages constituting the fine injection passage. Y1, Y2 ... Weft. C: A control computer constituting the first gripping air supply switching means and the second gripping air supply switching means. R: Weft insertion direction.

Claims (11)

An air provided with a gripping mechanism for mechanically gripping the weft by injecting the weft from the main nozzle for weft insertion by jetting the weft insertion air of the main nozzle for weft insertion provided with an acceleration pipe. In the weft gripping device in the jet loom,
The gripping mechanism includes a pressure introduction chamber for introducing gripping air,
A fine injection passage for causing fine injection to act on the wefts in the acceleration pipe is provided between the pressure introduction chamber and the inside of the acceleration pipe,
There is provided a first gripping air supply switching means for switching between a supply state for supplying gripping air to the pressure introduction chamber and a supply stop state for stopping the supply of gripping air to the pressure introduction chamber. And
There is provided a second gripping air supply switching means capable of switching between a discharge state in which the gripping air in the pressure introduction chamber is discharged to the fine injection passage and a discharge stop state in which the discharge of the gripping air in the pressure introduction chamber is stopped. And
The gripping mechanism grips the weft when the first gripping air supply switching means is in the supply state and the second gripping air supply switching means is in the discharge stop state,
The gripping mechanism is a weft gripping device in an air jet loom that releases the weft when the first gripping air supply switching means is in the supply stop state and the second gripping air supply switching means is in the discharge state.   The weft insertion air is supplied to the weft insertion main nozzle via an opening / closing valve, and the fine injection passage is discharged to join a weft insertion air passage connecting the opening / closing valve and the weft insertion main nozzle. The weft gripping device in an air jet loom according to claim 1, further comprising a check valve that is provided with a passage and that prevents backflow of weft insertion air in the discharge passage.   The fine injection passage is directly connected to the inside of the acceleration pipe, and a part of the fine injection passage is an oblique passage penetrating from the outer circumference to the inner circumference of the acceleration pipe. The weft gripping device in an air jet loom according to claim 1, wherein the weft gripping device has a shape that goes in the weft insertion direction from the outer periphery to the inner periphery of the acceleration tube.   The weft gripping device in the air jet loom according to any one of claims 2 and 3, wherein the gripping air in the pressure introduction chamber is discharged into the acceleration pipe before the start of weft insertion.   When the loom rotation speed is N rpm, the gripping air in the pressure introduction chamber is started to be discharged from the pressure introduction chamber at a loom rotation angle of 24 ° × N rpm / 800 rpm to 72 ° × N rpm / 800 rpm before the start of weft insertion. The weft gripping device in the air jet loom according to claim 4, wherein the discharge of the gripping air from the pressure introducing chamber and the injection of the weft inserting air are continuously performed.   The gripping mechanism includes a gripping member that presses the weft against an inner peripheral wall surface of the acceleration tube, and the gripping member presses against the inner peripheral wall surface when gripping air is supplied to the pressure introduction chamber. The weft gripping device in an air jet loom according to any one of claims 1 to 5, which is possible. The gripping mechanism includes a gripping member that presses the weft against an inner peripheral wall surface of the acceleration tube, and the gripping member presses against the inner peripheral wall surface when gripping air is supplied to the pressure introduction chamber. Is possible,
The fine injection passage is directly connected to the inside of the acceleration pipe, and a part of the fine injection passage is a through passage penetrating from the outer circumference to the inner circumference of the acceleration pipe. oriented gripping member, wherein by grasping air discharged from the through passage to the acceleration tract, weft holding device in the air jet loom according to claim 1 for urging the gripping member in a direction to release the weft.   The weft gripping device in an air jet loom according to claim 7, wherein the through passage has a shape that extends in a weft insertion direction from the outer periphery to the inner periphery of the acceleration tube.   The first gripping air supply switching means and the second gripping air supply switching means include a three-port valve type control valve, and the control valve supplies gripping air to the pressure introducing chamber. A first switching state in which a supply state and the discharge stop state in which the discharge of gripping air from the pressure introduction chamber is stopped; a supply stop state in which the supply of gripping air to the pressure introduction chamber is stopped; The weft gripping device in the air jet loom according to any one of claims 1 to 8, wherein the weft switching device is switched to a second switching state in which the discharge state in which gripping air is discharged from the pressure introduction chamber is taken. The gripping mechanism includes a gripping member that presses the weft against an inner peripheral wall surface of the acceleration tube, and a back pressure chamber partitioned from the pressure introduction chamber by the gripping member, and the first gripping air supply switching means And the second gripping air supply switching means comprises a five-port valve type control valve,
The control valve includes the supply state for supplying gripping air to the pressure introduction chamber, the discharge stop state for stopping the discharge of gripping air from the pressure introduction chamber, and the release air from the back pressure chamber. A gripping state that takes a back pressure release state that permits the release of gas, a supply stop state that stops the supply of gripping air to the pressure introduction chamber, and a discharge state that discharges the gripping air from the pressure introduction chamber The weft gripping device in the air jet loom according to any one of claims 1 to 8, wherein the gripping release state is switched between a gripping release state and a back pressure supply state in which release air is supplied to the back pressure chamber. The effective cross-sectional area of the control valve, the weft gripping device in an air jet loom according to any one of claims 9 and claim 10 is set to 1 mm ² to 3 mm ^2.

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