EP1437431A2

EP1437431A2 - Weft tension device for fluid-jet loom

Info

Publication number: EP1437431A2
Application number: EP03027860A
Authority: EP
Inventors: Norio Minamitani
Original assignee: Tsudakoma Industrial Co Ltd
Current assignee: Tsudakoma Corp
Priority date: 2003-01-10
Filing date: 2003-12-04
Publication date: 2004-07-14
Also published as: CN1517460A; EP1437431A3; JP2004218103A

Abstract

A weft tension device (10, 132) comprises: a tubular member (78) having a bore (82); an air-jet nozzle (86) disposed opposite to an inlet end of the tubular member and spaced by a picking path (80) from the inlet end of the tubular member; and a moving means (102) for making the air-jet nozzle and the tubular member approach relatively such that their largely spaced positions come into contact with each other from their spaced positions.

Description

Background of the Invention

Field of the Invention

The present invention relates to a weft tension device disposed on part near one end of a reed on the counterpicking side of the loom, and capable of tensing a picked weft yarn.

Description of the Related Art

Examples of weft tension devices include one previously disclosed in Japanese Patent Laid-open No. 3-241038 (Patent document 1). This weft tension device includes a primary air-jet nozzle held on part of a reed holder on the counterpicking side of a picking path extending along the reed of a loom along which a picked weft yarn travels straight, and a primary tubular member having an inlet opening and held on part of the reed holder on the counterpicking side of the picking path opposite to the primary air-jet nozzle. The air-jet nozzle and the primary tubular member are unable to move relative to each other. Air is jetted through the primary air-jet nozzle against a leading end part of a picked weft yarn to blow the leading end part of the weft yarn into the inlet opening of the primary tubular member. Thus, the picked weft yarn is tensed by the frictional effect of jetted air on the leading end part of the picked weft yarn.
This known weft tension device jets air through the primary air-jet nozzle for a catching period to force a leading end part of a picked weft yarn into the inlet opening of the primary tubular member, and for a tensing period to tension the weft yarn by the agency of air jetted through the primary air-jet nozzle.
In the catching period, air is jetted against the leading end part of the picked weft yarn to blow the leading end part into the inlet opening of the primary tubular member.
Generally, the catching period is timed such that the catching period is started before a leading end part of a picked weft yarn reaches the counterpicking side. Therefore, the leading end part is blown into the inlet opening of the primary tubular member immediately after the same has reached the counterpicking side.
Leading ends of successively picked weft yarns travel along different courses in the picking path, respectively, and the courses vary irregularly. Therefore, air must be jetted through the primary air-jet nozzle so as to cover a wide space around the primary tubular member entirely, and hence the tip of the primary air-jet nozzle and the inlet opening of the primary tubular member are spaced a comparatively long distance apart.
In the tensing period, air is jetted through the primary air-jet nozzle toward the leading end part of the weft yarn blown into the inlet opening of the primary tubular member to tense the picked weft yarn so that the picked weft may not slacken.
It is desirable to increase the velocity of air jetted through the primary air-jet nozzle in the inlet opening to the highest possible extent, provided that the weft yarn is not broken by the air. Thus, it is desirable that air be jetted through the primary air-jet nozzle at a high pressure. It is preferable that the tip of the primary air-jet nozzle and the inlet opening of the primary tubular member be spaced a short distance apart to make air flow at a high velocity in the inlet opening.
The weft tension device disclosed in Patent document 1 further includes a secondary tubular member having an open end placed in the primary tubular member, and a secondary air-jet nozzle capable of moving toward the open end of the secondary tubular member. A leading end part of a picked weft yarn blown into the primary tubular member by the air jetted through the primary air-jet nozzle and reached the open end of the secondary tubular member is blown into the secondary tubular member by air jetted through the secondary air-jet nozzle. Then, the secondary air-jet nozzle is moved toward the secondary tubular member to hold the leading end part of the picked weft yarn between the secondary air-jet nozzle and the secondary tubular member.
Patent document 1:
Japanese Patent Laid-open No. 3-241038
In this known weft tension device, the primary air-jet nozzle and the primary tubular member are fixedly held on the reed holder so that the primary air-jet nozzle and the primary tubular member are unable to move relative to each other. Therefore, the distance between the tip of the primary air-jet nozzle and the inlet opening of the primary tubular member is fixed during the catching and the tensing period, and hence the pressure of the air to be jetted through the primary air-jet nozzle must be considerably high to blow the leading end part of the picked weft yarn surely into the inlet opening of the primary tubular member.
Consequently, the weft tension device consumes much air and is incapable of efficiently tightening the picked weft yarn by jetting a small amount of air. Although the leading end part of the picked weft yarn is held between the secondary air-jet nozzle and the open end of the secondary tubular member, weft yarns are not necessarily picked in the same length and hence it is possible that the secondary air-jet nozzle and the open end of the secondary tubular member are not necessarily always able to hold a leading end part of a picked weft yarn successfully. Consequently, the different picked weft yarns picked in different weaving cycles are unstably differently tensed.

Summary of the Invention

Accordingly, it is an object of the present invention to provide a weft tension device for a fluid-jet loom, capable of efficiently catching a leading end part of a picked weft yarn.
The inventors of the present invention made earnest studies and have found that the shorter the distance between the tip of the air-jet nozzle and the inlet opening of the primary tubular member is, the higher the velocity of air in the inlet opening is and the higher the tension of the picked weft yarn is, and have made the present invention including a mechanism for reducing the distance between the tip of the air-jet nozzle and the inlet opening of the primary tubular member, and a mechanism for holding a leading end part of a picked weft yarn.
According to the first aspect of the present invention, a weft tension device comprises: a tubular member); an air-jet nozzle disposed opposite to an inlet end of the tubular member and spaced by a yarn path from the tubular member; and a moving means for making the air-jet nozzle and the tubular member approach relatively such that their largely spaced positions become small spaced positions or such that the air-jet nozzle is inserted in the tubular member with a gap maintained between the air-jet nozzle and the tubular member.
The term "yarn path" denotes a path including a straight picking path extending along the reed of the loom (a yarn guide groove and its extension when the reed is provided with modified dents), and a tensing path (the bore of the tubular member), into which a leading end part of a picked weft yarn is blown, substantially perpendicularly intersecting the picking path.
In the weft tension device according to the first aspect of the present invention, the air-jet nozzle is spaced a long distance apart from the inlet end of the tubular member and, therefore, a leading end part of a picked weft yarn can easily be blown into the tubular member in a catching period without being interfered with by the air-jet nozzle. In a tensing period, a blowing member forming a head part of the air-jet nozzle is moved near to or inserted in the inlet end of the tubular member. Consequently, a rapid air current is produced in the tubular member, so that the picked weft yarn is tensed strongly and held in the tubular member. Thus, the picked weft yarn can efficiently be tensed by using a small amount of air.
The inlet end of the tubular member may open into a picking path of the yarn path. When the inlet end of the tubular member is thus opened, the air-jet nozzle spaced a long distance apart from the tubular member is able to jet air toward the inlet end of the tubular member and a leading end part of a picked weft yarn can surely be blown into the tubular member even if the position of the picked weft yarn in a space between the air-jet nozzle and the inlet end of the tubular member changes every weaving cycle. Since air can be blown through the inlet end into the tubular member through the head part of the air-jet nozzle moved near to the inlet end of the tubular member, the pulling effect of the jetted air is enhanced. The air-jet nozzle is able to jet air from a position at a distance longer than that between the air-jet nozzle and the tubular member of the known weft tension device. Thus, a picked weft yarn is able to travel without being interfered with by the air-jet nozzle, and a leading end part of the picked weft yarn is able to reach surely a position between the air-jet nozzle and the inlet end of the tubular member.
According to the second aspect of the present invention, a weft tension device comprises a tubular member; an air-jet nozzle disposed opposite to an inlet end of the tubular member and spaced by a picking path from the inlet end of the tubular member; and a moving means for making the air-jet nozzle and the tubular member approach relatively such that the air-jet nozzle and the tubular member come into contact with each other from their spaced positions.
In the weft tension device according to the second aspect of the present invention, the air-jet nozzle is able to jet air toward the inlet end of the tubular member from a position distant from the inlet end of the tubular member. Hence, a leading end part of a picked weft yarn can travel without being interfered with by the air-jet nozzle, and a leading end part of a picked weft yarn can surely be blown into the tubular member even if the position of the picked weft yarn in a space between the air-jet nozzle and the inlet end of the tubular member changes every weaving cycle. Since the head part of the air-jet nozzle and the tubular member are moved relatively each other and the head part is brought into contact with the tubular member, the leading end part of the picked weft yarn can be held between the head part of the air-jet nozzle and the tubular member. Therefore, the picked weft yarn can be kept taut and does not slacken even if the air-jet nozzle stops jetting air. Thus, the amount of air to be jetted through the air-jet nozzle can be reduced.
According to the third aspect of the present invention, a weft tension device comprises: a tubular member having an inlet end opening into a picking path; an air-jet nozzle provided with a pressing member mounted thereon opposite to the inlet end of the tubular member and spaced by the picking path from the inlet end of the tubular member, and having a tip part inserted in the inlet end of the tubular member always; and a moving means for making the pressing member and the inlet end approach relatively from their spaced positions to come into contact with each other.
In the weft tension device according to the third aspect of the present invention, the tip part of the air-jet nozzle is placed always in the inlet end of the tubular member, all the air jetted through the air-jet nozzle flows into the bore of the tubular member, thereby a negative pressure is produced in the tubular member. Thus, a leading end part of a picked weft yarn traveling along the picking path is sucked efficiently into the bore of the tubular member when air is jetted through the air-jet nozzle. After the leading end part of the picked weft yarn has efficiently be sucked into the bore of the tubular member, the pressing member is brought into contact with the inlet end of the tubular member to hold the weft yarn firmly between the pressing member and the inlet end of the tubular member.
Therefore, the picked weft yarn can be kept in taut condition and does not slacken even if the air-jet nozzle stops jetting air. Thus, the amount of air to be jetted through the air-jet nozzle can be reduced.

Brief Description of the Drawings

Fig. 1 is a schematic perspective view of a weft tension device in the first embodiment according to the present invention as mounted on a loom;
Fig. 2 is a side elevation, taken from a picking side of the loom, of the weft tension device shown in Fig. 1;
Fig. 3 is a partly sectional side elevation, taken from the counterpicking side of the loom, of the weft tension device shown in Fig. 1 in a state in a catching period;
Fig. 4 is a time chart of assistance in explaining the operation of the weft tension device shown in Fig. 1;
Fig. 5 is a partly sectional side elevation, taken from the counterpicking side of the loom, of the weft tension device shown in Fig. 1 in a state in a tensing period;
Figs. 6(A) and 6(B) are sectional views of an essential part of a weft tension device in a modification of the weft tension device shown in Fig. 1 in a catching period and a tensing period, respectively;
Figs. 7(A) and 7(B) are sectional views of an essential part of a weft tension device in the second embodiment according to the present invention in a catching period and a tensing period, respectively;
Fig. 8 is a time chart of assistance in explaining the operation of the weft tension device shown in Fig. 7;
Fig. 9 is a sectional view of an essential part of a weft tension device in a modification of the weft tension device shown in Fig. 7 in a state in a tensing period;
Figs. 10(A) and 10(B) are sectional views of an essential part of a weft tension device in the third embodiment according to the present invention in a state in a catching period and in a state in a tensing period, respectively;
Fig. 11 is a sectional view taken on line 11-11 in Fig. 10(A);
Figs. 12(A) and 12(B) are sectional views of an essential part of a weft tension device in the fourth embodiment according to the present invention in a state in a catching period and in a state in a tensing period, respectively;
Figs. 13(A) and 13(B) are sectional views of an essential part of a weft tension device in the fifth embodiment according to the present invention in a state in a catching period and in a state in a tensing period, respectively; and
Fig. 14 is a sectional view of a weft tension device in the sixth embodiment according to the present invention.

Detailed Description of the Preferred Embodiments

First Embodiment

Referring to Figs. 1 to 5, a weft tension device 10 in the first embodiment according to the present invention is disposed near one end of a reed 12 on the counterpicking side of a loom 14. The weft tension device 10 is detachably firmly attached to a reed holder 16 detachably attached to the arm (not shown), of the loom 14. The weft tension device 10 swings back and forth together with the reed 12 and catches a picked weft yarn 18 to tense the same.
As shown in Figs. 1 and 2, the reed 12 includes an upper bar (upper holding member) 22, a lower bar (lower holding member) 24, a plurality of dents 20 extended between the upper bar 22 and the lower bar 24, and side bars (connecting members) 26 connecting the upper bar 22 and the lower bar 24. In Fig. 2, a middle part of the side bar 26 is omitted.
Each of the dents 20 is vertically elongated, and has thin plate of a substantially uniform thickness having rounded upper and lower ends. The dent 20 has a front edge (front part) 28 on the side of the cloth fell of a fabric 64 on the loom 14, and a back edge (back part) 30 facing the heald frames of the loom 14.
A middle part of the front edge 28 of the dent 20 is protruded to form a substantially triangular protrusion 32. A recess 34 is formed in a top part of the protrusion 32. The recess 34 is defined by two side edges 36 and a round bottom edge (bottom part) 38 smoothly merging into the side edges 36. The back edge 30 of the dent 20 is substantially straight.
The dents 20 are formed of stainless steel and are elastic.
The upper bar 22 and the lower bar 24 are provided with grooves 40 and 42 and have U-shaped sectional shapes, respectively.
The side bars 26, 26 are strip-shaped plates of a thickness greater than that of the dents 20, have bent opposite ends and have a U-shape.
The width of the side bars 26 26, i.e., size in the moving direction of warp yarns 44, is determined so that the side bars 26 may not obstruct the movement of a picked weft yarn 18; that is, the width of the side bars 26 is smaller than that of a part between the bottom edge 38 of the recess 34 and the back edge 30 of the dent 20.
The upper bar 22, the lower bar 24 and the side bars 26, 26 are assembled in a reed frame with the dents 20 extended between the upper bar 22 and the lower bar 24. The upper and the lower ends of the dents 20 are fitted in the respective grooves 40 and 42 of the upper bar 22 and the lower bar 24. The dents 20 are arranged in parallel to each other at predetermined intervals along a picking direction with their thicknesses in parallel to the picking direction. Thus, the recesses 34 of the dents 20 define a yarn guide groove 46.
Spaces 48 (Fig. 11) of a width suitable for passing the warp yarns 44 and waste warp yarns 52 therethrough are formed between the adjacent dents 20. The width of the spaces 48 is determined by upper and lower spacers 50 and 50, contiguous with the upper bar 22 and the lower bar 24. Practically, each spacer 50 is coil spring having coil portions spacing the adjacent dents 20 to form the spaces 48.
The loom 14 is provided with sub picking nozzles 54. Each sub picking nozzle 54 is held detachably on a nozzle holder 56. The sub picking nozzle 54 is passed through a through hole formed in the nozzle holder 56 and is fastened to the nozzle holder 56 with, for example, a cross-recessed head screw 58.
A weft detector 60 for detecting a picked weft yarn 18 is held by a detector holder 62 at a position near a selvage of the fabric 64 on the counterpicking side with its detecting head positioned opposite to the yarn guide groove 46 formed by the recesses 34 of the plurality of dents 20. The weft feeler, i.e., weft detector 60 detects a picked weft yarn 18 when a leading end part of the picked weft yarn 18 reaches the end of the yarn guide groove 46 on the counterpicking side.
The reed holder 16 is provided with grooves 66 and 68. The reed 12, the sub picking nozzles 54, the weft detector 60 and the weft tension device 10 are detachably attached to the reed holder 16 by using the grooves 66 and 68 so that the respective positions of the reed 12, the sub picking nozzles 54, the weft detector 60 and the weft tension device 10 with respect to the picking direction are adjustable.
Referring to Fig. 3, the weft tension device 10 is disposed at a position near the end of the reed 12 on the counterpicking side, and includes an L-shaped catching pipe (tubular member) 78, an air-jet nozzle 86, and a solenoid device 102 for axially moving the air-jet nozzle 86. The air-jet nozzle 86 has a nozzle hole 84, and is disposed so as to oppose to the inlet end of the bore 82 of the catching pipe 78, and spaced by a picking path 80, i.e., an extension of the yarn guide groove 46 in the picking direction, from the inlet end of the catching pipe 78.
The air-jet nozzle 86 has integrally a tubular front part 88 of a small outside diameter, and a tubular back part 90 of a big outside diameter coaxial with the front part 88. The joint of the front part 88 and the back part 90 is truncated conical shape.
The front section 88 is integrally provided with a front flange 92 at its front end opposite to the back part 90, and a middle flange 94 at its middle. The back part 90 is integrally provided with a back flange 96 at its back end opposite to the front part 88. The air-jet nozzle 86 is formed of a magnetic material, such as iron.
The air-jet nozzle 86 has an axial through hole 98 coaxial with the front part 88 and the back part 90. The through hole 98 has opposite open ends opening in central parts of the front flange 92 and the back end of the back part 90, respectively. The front end of the through hole 98 serves as a spout 84. The back end of the through hole 98 communicates with a hose 100 firmly connected to the back end part of the air-jet nozzle 86. A loom controller controls the supply of compressed air from an air source, such as an air compressor, through the hose 100 to the air-jet nozzle 86 to jet air through the air-jet nozzle 86.
The solenoid device 102 has a solenoid 104 formed by winding a wire round a hollow bobbin and encased in a cylindrical housing 106. The back part 90 of the air-jet nozzle 86 is fitted axially slidably in the bore of the hollow bobbin. Bushings 108 and 108 are fitted respectively in a front end part, corresponding to the front part 88, and a back end part, corresponding to the back part 90, of the cylindrical housing 106 to ensure that the back part 90 is able to move smoothly relative to the solenoid 104.
A return spring 110 is disposed, at compressed state, between the housing 106 and the back flange 96 of the back part 90 to push the flange 96 of the air-jet nozzle 86 away from the housing 106.
An solenoid holder 112 has a leg 114 detachably attached to the reed holder 16, a ring-like solenoid-holding part 116 holding the solenoid device 102, a nozzle-holding part 118 axially slidably holding the front part 88 of the air-jet nozzle 86, and a pipe-holding part 120 holding part of the L-shaped catching pipe 78.
Referring to Fig. 3, the solenoid-holding part 116, the nozzle-holding part 118 and the pipe-holding part 120 have circular through holes 122, 124 and 126 of different diameters, respectively. The through holes 124 and 126 are coaxial. The through holes 124 and 126 do not necessarily need to be coaxial depending on the traveling mode of a picked weft yarn 18.
The nozzle holding part 118 and the pipe holding part 120 are spaced by a U-shaped groove 128. The through holes 124 and 126 open in the opposite side surfaces of the groove 128, respectively.
A bushing 130 is fitted in the through hole 124 of the nozzle holding part 118 to enable a part between the front flange 92 and the middle flange 94 of the front part 88 of the air-jet nozzle 86 to slide smoothly relative to the nozzle-holding part 118. Thus, the part between the flanges 92 and 94 of the front part 88 of the air-jet nozzle 86 is supported slidably by the bushings 130 on the nozzle-holding part 118.
One end part of the catching pipe 78 is fitted in the through hole 126 of the pipe-holding part 120. The end part of the catching pipe 78 is held opposite to the through hole 98 opening in the front flange 92 of the air-jet nozzle 86 and is spaced from the front flange 92 by the groove 128.
The solenoid holder 112 is disposed at a position near the end of the reed 12 on the counterpicking side. The leg 114 of the solenoid holder 112 can be moved for positional adjustment along the groove 66 extending along the width of the fabric 64. The position of the solenoid holder 112 is determined such that the nozzle-holding part 118 and the pipe-holding part 120 are on the opposite sides of the picking path 80 as an extension of the yarn guide groove 46, i.e., the picking path 80 extends through the groove 128. The leg 114 of the nozzle holder 112 is detachably fastened in the groove 66 of the reed holder 16 with a wedge 70.
The operation of the weft tension device 10 is operated by the timing corresponding to the basis of the angular position of the main shaft of the loom 14 measured by a rotary encoder or the like. As shown in Fig. 4, air is jetted through the air-jet nozzle 86, for example, for an angular period between angular positions  of 200° and 310°, and the solenoid 104 is energized for an angular period between angular positions  of 300° and 350° to bring the air-jet nozzle 86 into contact with the inlet end of the catching pipe 78.
The operation of the weft tension device 10 will be described with reference to Fig. 4.
In a state where the front flange 92 of the air-jet nozzle 86 is spaced from the inlet end of the catching pipe 78, a weft yarn 18 is picked into the shed of the warp yarns 44 and 52 from the picking side of the loom 14.
Then, prior to the passing of the leading end part of the weft yarn 18 through the groove 128 of the solenoid holder 112, when angular position  of the main shaft of the loom 14 coincides with a predetermined angular position of, for example, 200°, the air-jet nozzle 86 starts jetting compressed air. The air flows across the groove 128, flows through the inlet end into the bore 82 of the catching pipe 78, and flows outside the catching pipe 78 through an outlet end opposite the inlet end of the catching pipe 78.
Upon arrival of a leading end part of the picked weft yarn 18 at a predetermined position on the counterpicking side, the weft detector 60 gives a weft detection signal indicating that the weft yarn 18 is picked successfully to the loom controller (not shown). As shown in Fig. 4, the weft detector 60 provides the detection signal indicating the presence or absence of the weft yarn 18 when the angular position  of the main shaft is 240°.
When the main shaft is at the angular position of 240°, the solenoid 104 is not energized and hence the air-jet nozzle 86 is retracted by the return spring 110 such that the middle flange 94 is in contact with the bushing 108 as shown in Fig. 3.
In a catching period, in which the air-jet nozzle 86 is jetting compressed air, and the front flange 92 is thus spaced from the inlet end of the bore 82 of the catching pipe 78, the air-jet nozzle 86 does not interfere with the picked weft yarn 18 traveling along the picking path 80, and a leading end part of the picked weft yarn 18 can surely be forced into the bore 82 of the catching pipe 78 even if the respective positions of picked weft yarns picked by successive weaving cycles in the space between the front flange 92 of the air-jet nozzle 86 and the inlet end of the catching pipe 78 are different.
The groove 128 is in the picking path 80 on an extension of the guide groove 46, and the air-jet nozzle 86 starts jetting air before the weft detector 60 detects the picked weft yarn 18. Therefore, a leading end part of the picked weft yarn 18 is carried forcibly through the inlet end of the groove 128 into the bore 82 of the catching pipe 78 by air currents jetted through the air-jet nozzle 86 upon arrival at a position corresponding to the inlet end of the catching pipe 78.
Fig. 3 shows the condition of the weft tension device 10 when the angular position  of the main shaft of the loom 14 is 250°. In this condition the air jetted through the air-jet nozzle 86 forces the leading end part of the picked weft yarn 18 into the bore 82 of the catching pipe 78, that is, pulls it from the side of the groove 128 of the bore 82 to the side opposite to the groove 128, so that the picked weft yarn 18 is tensed.
In the state that the picked weft yarn 18 has thus been tensed, the solenoid 104 is energized when the angular position  of the main shaft is 300° (Fig. 4). Then, the air-jet nozzle 86 jetting air is advanced against the resilience of the return spring 110 toward the inlet end of the catching pipe 78, and the front flange 92 of the air-jet nozzle 86 is brought into contact with the inlet end of the catching pipe 78 as shown in Fig. 5.
In a tensing period, in which the solenoid 104 is energized and the front flange 92 of the air-jet nozzle 86 comes into contact with the inlet end of the catching pipe 78 to close the inlet of the bore 82, the pressure of the compressed air supplied to the air-jet nozzle 86 is maintained at the level of the pressure of the compressed air that is supplied to the air-jet nozzle in the catching period.
In the tensing period, the intensity of the air current flowing through the bore 82 of the catching pipe 78 increases as the front flange 92 of the air-jet nozzle 86 approaches the inlet end of the catching pipe 78, thereby the pulling force acting on the leading end part of the picked weft yarn 18 is increased. Thus, the picked weft yarn 18 can efficiently be pulled even if air is jetted through the air-jet nozzle 86 at a low jetting rate.
The front flange 92 is kept in contact with the inlet end of the catching pipe 78 to hold the picked weft yarn 18 between the front flange 92 of the air-jet nozzle 86 and the inlet end of the catching pipe 78 as shown in Fig. 5 after the termination of the tensing period.
The air-jet nozzle 86 stops jetting air at a predetermined point in the weaving cycle corresponding to the angular position  of 350° (Fig. 4). The picked weft yarn 18 does not slacken until the solenoid 104 is de-energized because the picked weft yarn 18 is held between the front flange 92 of the air-jet nozzle 86 and the inlet end of the catching pipe 78.
The solenoid 104 is de-energized at a predetermined point in the weaving cycle, such as a point corresponding to the angular position  of 350° in Fig. 4), immediately before or after the shed is closed.
As shown in Fig. 3, after the solenoid 104 has been de-energized, the air-jet nozzle 86 is retracted by the resilience of the return spring 110, and the front flange 92 of the air-jet nozzle 86 is separated from the inlet end of the catching pipe 78 to release the picked weft yarn 18.
Figs. 6(A) and 6(B) show the positional relation between an air-jet nozzle 86 and a catching pipe 78 included in a weft tension device 132 in a modification of the weft tension device in the first embodiment in states where the angular positions  are 250° in a catching period and 330° in a tensing period, respectively.
Referring to Figs. 6(A) and 6(B), the air-jet nozzle 86 is provided with a truncated conical shape tip member 134 formed of an elastic material instead of the front flange 92, at the tip of the front part 88 of the air jet nozzle 86. The inside surface of the inlet end of the catching pipe 78 is shaped in a flared inside surface of a shape corresponding to that of the tip member 134 so that the tip member 134 may come into close contact with the inside surface of the inlet end of the catching pipe 78.
Preferably, the tip member 134 is formed of a highly frictional, elastic material, such as urethane rubber.
The tip member 134 put on the air-jet nozzle 86 is brought into contact with the inlet end of the catching pipe 78 to hold a picked weft yarn 18 between the tip member 134 and the inlet end of the catching pipe 78. The shape tip member 134 is elastically deformed when the same is pressed against the inlet end of the catching pipe 78. Thus, the length of part of the picked weft yarn 18 held between the truncated conical shape tip member 134 and the inlet end of the catching pipe 78 is longer than that of the picked weft yarn 18 held between the front flange 92 and the catching pipe 78 of the first embodiment. Thus, the weft tension device 132 is capable of more firmly holding the picked weft yarn 18 than the weft tension device 10 in the first embodiment.
The weft tension device in the first embodiment catches and holds the leading end part of the picked weft yarn 18 that arrives at a position corresponding to the inlet end, opening into the picking path 80, of the catching pipe 78, i.e., a tubular member. Therefore, picked weft yarns 18 respectively having different lengths and short picked weft yarns 18 can surely be caught and held. Thus, the length of the picked weft yarns 18 can be reduced, thereby weaving cost can be reduced.

Second Embodiment

Referring to Figs. 7(A) and 7(B), a weft tension device 136 in a second embodiment according to the present invention has an air-jet nozzle 86 having a tubular front part 88 provided with a reduced tip part 138 instead of the front flange 92. The outside diameter of the reduced tip part 138 is smaller than the inside diameter of the inlet end of a catching pipe 78.
As shown in Fig. 8, the air-jet nozzle 86 continues jetting air and a solenoid 104 continues being energized until a point of time immediately before or after the shed is closed.
The operation of the weft tension device 136 will be described.
The air-jet nozzle 86 starts jetting air through its nozzle hole 84 when the angular position  of the main shaft of the loom14 is 200° for a catching period. In the catching period, the tip part 138 of the air-jet nozzle 86 is held outside a picking path 80 as shown in Fig. 7(A).
In this state, since the tip part 138 is not inserted in the bore 82 of the catching pipe 78, air jetted through the air-jet nozzle 86 diffuses. Therefore, a leading end part of each of picked weft yarns 18 can surely be forced into the bore 82 of the catching pipe 78 even if the picked weft yarns 18 along different courses, respectively, in the picking path 80.
Then, in a tensing period, the solenoid 104 is energized to advance the air-jet nozzle 86 toward the catching pipe 78 as far as the end of the tip part 138 of the air-jet nozzle 86 is located close to the inlet end of the catching pipe 78. Since the tip part 138 of the air-jet nozzle 86 is located close to the inlet end of the catching pipe 78, that is, the interval between the tip part 138 and the inlet end of the catching pipe 78 is reduced toward to a small value from a large value, most part of air jetted through the nozzle hole 84 of the air-jet nozzle 86 is blown into the bore 82 of the catching pipe 78 and flows outside the catching pipe 78 through an outlet end opposite the inlet end of the catching pipe 78. Fig. 7(B) shows the positional relation between the air-jet nozzle 86 and the catching pipe 78 of the weft tension device 136 when the angular position  is 330° in a sectional view.
Air jetted through the air-jet nozzle 86 into the bore 82 produces a reduced pressure in the bore 82. Consequently, air currents flow through the gap between the inlet end of the catching pipe 78 and the outer surface of the tip part 138 of the air-jet nozzle 86 into the bore 82, and the leading end part of the picked weft yarn 18 is pulled efficiently into the bore 82 by the combined effect of the air jetted through the nozzle hole 84 of the air-jet nozzle 86 and the air currents.
The air-jet nozzle 86 of the weft tension device 136 may be advanced such that the tip part 138 of the air-jet nozzle 86 is inserted in the bore 82 of the catching pipe 78 as shown in Fig. 9. When the air-jet nozzle 86 spaced from the catching pipe 78 is moved toward the catching pipe 78, and the tip part 138 is inserted in the bore 82 of the catching pipe 78 so that a gap is formed between the inner surface of the catching pipe 78 and the outer surface of the tip part 138, all the air jetted through the nozzle hole 84 of the air-jet nozzle 86 flows into the bore 82 of the catching pipe 78 and flows outside through the outlet end of the catching pipe 78.
The insertion of the tip part 138 in the bore 82 of the catching pipe 78 further reduces the pressure in the bore 82, and the intensity of the air current flowing through the gap between the inner surface of the catching pipe 78 defining the bore 82 and the outer surface of the tip part 138 of the air-jet nozzle 86 into the bore 82 is further increased. Consequently, the leading end part of the picked weft yarn 18 is pulled more efficiently into the bore 82 by the combined effect of the air jetted through the nozzle hole 84 of the air-jet nozzle 86 and the air currents.

Third Embodiment

Referring to Figs. 10(A), 10(B) and 11, a weft tension device 140 in the third embodiment according to the present invention has a rockable air-jet nozzle 142, an L-shaped catching pipe 144, i.e., a tubular member, detachably attached to a nearby part of a reed 12 provided with dents 20, and a nozzle holder 146 provided with a nozzle rocking mechanism for rocking the air-jet nozzle 142.
The nozzle holder 146 holding the air-jet nozzle 142 is detachably fastened to a reed holder 16 of a loom 14. The nozzle rocking mechanism included in the nozzle holder 146 includes a rotary solenoid actuator capable of rocking the air-jet nozzle 142 on a shaft 148 extending in parallel to the picking direction in an angular range.
The L-shaped catching pipe 144 is provided with two diametrically opposite parallel pins 150 projecting from the inlet end of the catching pipe 144 toward the air-jet nozzle 142. A holding arm 152 holding the catching pipe 144 is detachably attached to the part, on the counterpicking side of the loom 14, of the reed 12. More specifically, the holding arm 152 extends toward and is attached to the upper bar 22 of the reed frame of the reed 12.
As shown in Fig. 11, the two pins 150 are vertically spaced apart and are extended through a space 48 between the adjacent dents 20. The diameter of the pins 150 is far greater than the disposition pitches of the adjacent dents 20. Thus, the width of the space 48 through which the pins 150 are extended is increased, and several ones of the dents 20 on the opposite sides of the space 48 through which the pins 150 are extended are pushed toward the picking side and the counterpicking side so as to deform elastically by the pins 150. Consequently, spaces 48 near the space 48 through which the pins 150 are extended are narrowed. Thus, air jetted through the air-jet nozzle 142 flows through the expanded space 48, the narrowed spaces 48 obstruct the flow of air jetted through the air-jet nozzle 142. The two pins 150 and the two dents 20 in contact with the two pins 150 define a space 154 connected to the bore of the catching pipe 144.
A shaded area in Fig. 10(A) is the space 154. The space 154 is defined by a height, i.e., a vertical dimension, between the two pins 150, a width, i.e., a lateral dimension, between the two dents 20 in contact with the two pins 150, and a depth, i.e., a longitudinal dimension, between the back edge 30 of the dent 20 and the bottom 38 of a recess 34 formed in the dent 20.
Thus, the two pins 150 and the two dents 20 in contact with the two pins 150 act as a part of a tubular member.
A mode of timing the operation of the weft tension device 140 is the same as that previously described with reference to Fig. 8. The solenoid of the rotary solenoid actuator is energized at the time shown in Fig. 8. The air-jet nozzle 142 jets air in an angular range of the angular position  of the main shaft of the loom between angular positions 200° and 350°. The solenoid of the rotary solenoid actuator is energized in an angular range of the angular position  between angular positions 300° and 350° to turn the air-jet nozzle 142 so that the tip of the air-jet nozzle approaches the space 154.

Fourth Embodiment

Referring to Figs. 12(A) and 12(B), a weft tension device 156 in the fourth embodiment according to the present invention has an air-jet nozzle 86 having a tubular front part 88 provided with a reduced tip part 138. The tip part 138 of the air-jet nozzle 86 of the weft tension device 156 in the fourth embodiment is longer than that of the air-jet nozzle 86 of the weft tension device 136 shown in Fig. 7 in the second embodiment. The air-jet nozzle 86 is disposed such that a front end part of the tip part 138 lies always in the bore 82 of a catching pipe 78. A pressing member 158 is put on the tip part 138 so as to rest on the shoulder of the front part 88 of the air-jet nozzle 86 and to face the inlet end of the catching pipe 78.
Preferably, the pressing member 158 is formed of an elastic material, such as urethane rubber, to ensure that a picked weft yarn 18 is held firmly between the pressing member 158 and the inlet end of the catching pipe 78 flush with the side surface of a groove 128 of a solenoid holder 112 (Fig. 3) as shown in Fig. 12(B).
In a catching period for catching a leading end part of a picked weft yarn 18, the tip part 138 lies in the bore 82 of the catching pipe 78, and the pressing member 158 is spaced from the inlet end of the catching pipe 78. Therefore, the effect of the weft tension device 156 in the catching period is the same as that of the weft tension device 136 shown in Fig. 9.
Air jetted through the nozzle hole 84 of the air-jet nozzle 86 into the bore 82 produces a reduced pressure in the bore 82. Consequently, air currents flow through the gap between the inner surface of the catching pipe 78 defining the bore 82 and the outer surface of the tip part 138 of the air-jet nozzle 86 into the bore 82, and the leading end part of the picked weft yarn 18 is pulled efficiently into the bore 82 by the combined effect of the air jetted through the nozzle hole 84 of the air-jet nozzle 86 and the air currents.
Then, as shown in Fig. 12 (B), a solenoid 104 is energized to advance the air-jet nozzle 86 toward the catching pipe 78 for a tensing period. The pressing member 158 is pressed against the inlet end of the catching pipe 78 to hold the picked weft yarn 18 firmly between the elastic pressing member 158 and the inlet end of the catching pipe 78.
After holding the picked weft yarn 18 between the pressing member 158 and the inlet end of the catching pipe 78, the air-jet nozzle 86 may stop jetting air. Thus, the amount of air can be reduced.

Fifth Embodiment

Referring to Figs. 13(A) and 13(B), a weft tension device 160 in the fifth embodiment according to the present invention has an air-jet nozzle 162 having a slide pipe 164 axially slidably held opposite to the inlet end of a catching pipe 78. A pressing member 158 is put on the front end of the slide pipe 164, and a tubular front part 88 provided with a nozzle hole 84 and inserted in the slide pipe 164 so as to permit the slide pipe 164 to slide axially relative to the front part 88. Normally, the slide pipe 164 is spaced from the inlet end of the catching pipe 78 by a picking path 80.
A moving mechanism including a drive device, such as a solenoid, advances the slide pipe 164 spaced apart from the catching pipe 78 toward the catching pipe 78 to bring the pressing member 158 into contact with the inlet end of the catching pipe 78.
The moving mechanism retracts the slide pipe 164 of the weft tension device 160 to hold the pressing member 158 outside the picking path 80 in a catching period as shown in Fig. 13(A).
In the catching period, air is jetted through the nozzle hole 84 of the air-jet nozzle 162 to suck a leading end part of a picked weft yarn 18 into the bore 82 of the catching pipe 78.
In a tensing period, the moving mechanism advances the slide pipe 164 toward the catching pipe 78. Consequently, the pressing member 158 advances across the picking path 80 and comes into contact with the inlet end of the catching pipe 78 and the side surface of a groove 128 formed in a solenoid holder 112 (Fig. 3) as shown in Fig. 13(B). Thus, the picked weft yarn 18 is held firmly between the pressing member 158 and the catching pipe 78.

Sixth Embodiment

Referring to Fig. 14, a weft tension device 166 in the sixth embodiment according to the present invention has a secondary air-jet nozzle 172, a suction pipe 170, a catching pipe 78, a primary air-jet nozzle 86, a cylinder 168, and a rotary solenoid actuator 176 provided with an arm 180.
The suction pipe 170 has an open front end and a closed back end, and is provided with openings in diametrically opposite parts of its side wall near the closed back end. One end of the catching pipe 78 is fitted in one of the opening of the suction pipe 170, and the cylinder 168 is connected to the other opening.
The secondary air-jet nozzle 172 is disposed opposite to the open front end of the suction pipe 170, and is spaced from the open front end of the suction pipe 170 by a picking path 80.
The primary air-jet nozzle 86 has a front part 88 of a small outside diameter, and a back part 90 of a big outside diameter coaxial with the front part 88. The back part 90 of the primary air-jet nozzle 86 is slidably fitted in the cylinder 168. The back part 90 is interlocked with the arm 180 by pins 174 attached thereto. The front part 88 of the primary air-jet nozzle 86 can be moved toward and away from the inlet end of the catching pipe 78 in the suction pipe 170.
The secondary air-jet nozzle 172, the suction pipe 170 and the rotary solenoid actuator 176 are held to a reed holder 16 of a loom 14 by a solenoid holder 112.
A yarn path has a picking path 80 extending in a picking direction, and an L-shaped suction path 190 connected to the picking path 80, and having a first section extending in the suction pipe 170 and a second section extending in the catching pipe 78 and perpendicular to the first section. Thus, the yarn path is substantially cranked. The primary air-jet nozzle 86 is disposed opposite to the inlet end of the catching pipe 78 and spaced from the inlet end by the suction path 190 of the suction pipe 170. Air jetted through the primary air-jet nozzle 86 flows substantially straight into the catching pipe 78. Therefore, flow resistance of the jetted air is low, the jetted air maintains a high velocity. Hence, an leading end part of a picked weft yarn 18 forced into the suction pipe 170 by air jetted through the secondary air-jet nozzle 172 can efficiently be held in the catching pipe 78.
The primary air-jet nozzle 86 has a pair of the pins 174 attached to the large part 90, and extended in diametrically opposite directions through a pair of slots 182 formed diametrically opposite to each other in the sidewall of the cylinder 168. The pins 174 are projected the outside on the cylinder 168 so as to be inserted into the slots 184 formed in a pair of front ends of the arm 180, and are interlocked with the arm 180.
The arm 180 is mounted on the drive shaft 178 of the rotary solenoid actuator 176 so as to be not moved each other. The drive shaft 178 is turned counterclockwise through a predetermined angle from the position shown in Fig. 14 to insert the tip part of the primary air-jet nozzle 86 in the bore 82 of the catching pipe 78 such that a gap is formed between the tip part of the primary air-jet nozzle 86 and the catching pipe 78.
The solenoid of the rotary solenoid actuator 176 is energized in the catching period to turn the drive shaft 178 of the rotary solenoid actuator 176 counterclockwise as viewed in Fig. 14, thereby the arm 180 is angularly rotated in the same direction. Consequently, the arm 180 moves the primary air-jet nozzle 86 in position spaced apart from the bore 82 toward the bore 82, and the tip of the primary air-jet nozzle 86 is inserted in the catching pipe 78 such that a clearance is formed between the tip of the primary air-jet nozzle 86 and the catching pipe 78.
Since the tip part of the primary air-jet nozzle 86 is inserted in the bore 82 of the catching pipe 78 such that the gap is formed between the tip part of the primary air-jet nozzle 86 and the catching pipe 78, the picked weft yarn 18 is not held between the primary air-jet nozzle 86 and the catching pipe 78, and straight currents of air jetted through the primary air-jet nozzle 86 produces a negative pressure in the catching pipe 78. Thus, the picked weft yarn 18 is pulled and tensed by suction produced by the air flowing into the catching pipe 78 even if the picked weft yarn 18 is short and the leading end thereof is unable to reach the catching pipe 78. Thus, the picked weft yarn 18 can be tensed regardless of the length thereof, provided that the length is within a permissible range.

Modifications

Although the moving mechanisms included in the foregoing all of embodiments employ the solenoid as a driving device, the weft tension devices of the present invention may employ any suitable moving mechanism, such as a linear or rotary electric actuator, a linear or rotary pneumatic actuator, or a mechanical device including cams and links. Such a mechanical device may be driven by another driving device.
When the picked weft yarn 18 is held between the catching pipe 78, and the tip of the air-jet nozzle 86 or the pressing member 158, the air-jet nozzle 86 may stop jetting air after the picked weft yarn 18 has been held between the catching pipe 78, and the tip of the air-jet nozzle 86 or the pressing member 158 to reduce the amount of air for catching and tensing the picked weft yarn 18.
Although the invention has been described in its preferred embodiment, the present invention is not limited thereto in its practical application and various changes and modifications may be made therein without departing from the scope of the invention.

Claims

A weft tension device comprising:

a tubular member (78, 144);

an air-jet nozzle (86, 142) disposed opposite to an inlet end of the tubular member and spaced by a yarn path (80,190) from the tubular member; and

a moving means (102) for making the air-jet nozzle and the tubular member approach relatively such that their largely spaced positions become small spaced positions or such that the air-jet nozzle is inserted in the tubular member with a gap maintained between the air-jet nozzle and the tubular member.
The weft tension device according to claim 1, wherein the inlet end of the tubular member (78, 144) opens into a picking path (80) of the yarn path.
A weft tension device comprising:

a tubular member (78);

an air-jet nozzle (86) disposed opposite to an inlet end of the tubular member and spaced by a picking path (80) from the inlet end of the tubular member; and

a moving means (102) for making the air-jet nozzle and the tubular member approach relatively such that the air-jet nozzle and the tubular member come into contact with each other from their spaced positions.
A weft tension device comprising:

a tubular member (78) having an inlet end opening into a picking path (80);

an air-jet nozzle (86, 162) provided with a pressing member (158) mounted thereon opposite to the inlet end of the tubular member and spaced by the picking path (80) from the inlet end of the tubular member, and having a tip part inserted in the inlet end of the tubular member always; and

a moving means (102) for making the pressing member and the inlet end approach relatively from their spaced positions to come into contact with each other.