Apparatus for guiding weft yarns in a jet loom

An apparatus is provided for guiding a weft yarn into the shed of a jet loom by a number of weft guiding members, each having an aperture with an opening. The weft guiding members are composed of a first group of weft guiding members of which the openings are of a relatively narrow width and formed in upper parts of the weft guiding members in the first group, and a second group of weft guiding members of which the openings are of a relatively broad width and formed in side parts of the weft guiding members in the second group. In front of the opening in each of the weft guiding members in the second group are sub-nozzles each having at least one fluid outlet discharging a jet of fluid to assist the weft yarn in being inserted into the shed so that the fluid jet produced by the respective sub-nozzle is obliquely directed toward surfaces of the apertures of the weft guiding members in the first group downstream of the respective sub-nozzle with respect to the direction in which the weft yarn is inserted, which surfaces are positioned on the side opposite to the sub-nozzles.

BACKGROUND OF THE INVENTION 
This invention relates to an apparatus for guiding a weft yarn passing 
through a shed formed between warp yarns in a so-called jet loom. 
In the past, in order to insert the weft yarn more smoothly into the shed 
formed between the upper and lower warp yarns, various designs for a weft 
yarn guiding apparatus have been produced. For example, a guiding 
apparatus has been known, which comprises a number of weft yarn guiding 
members arranged in spaced relationship in the direction of the weft 
insertion with apertures forming a continuous channel, through which the 
weft yarn is passed during the insertion thereof, each aperture having a 
large opening formed on the side of the reed, and a suitable number of 
sub-nozzles positioned in places along the channel so that their fluid 
outlets open into the channel. With this guiding apparatus, during the 
insertion of the weft yarn, the weft yarn is fed into the channel by a jet 
of fluid produced by a main nozzle positioned in alignment with the 
channel, while each of the sub-nozzles produces a jet of fluid acting on 
the weft yarn in cooperation with the main jet of fluid to make up the 
shortage of feed distance of the weft yarn, which would occur if the 
sub-nozzles were not employed, thus assisting the weft yarn in being fed 
smoothly through the channel. 
However, in the afore-mentioned apparatus, because of the large opening 
formed in each of the weft guiding members, the fluid discharged from both 
the main and sub-nozzles is subject to escape from the openings, resulting 
in a greater consumption of the fluid. Moreover, because the jet of fluid 
produced by each sub-nozzle is directed toward the downstream weft guiding 
members at a certain angle with respect to the weft inserting direction so 
as to blow against the aperture surfaces of the downstream weft guiding 
members opposite to the large openings and thereafter is deflected at a 
large angle close to about 90.degree. with respect to the weft inserting 
direction, i.e., the weft yarn being fed through the apertures, the 
leading end of the weft yarn is apt to be entrained by the deflected flow 
of fluid, resulting in the disadvantage of passing out of the channel 
through the large openings during the insertion of the weft yarn. Such a 
disadvantage would be conspicuous especially when the leading end of the 
weft yarn deviates from the path of the main jet of fluid produced by the 
main nozzle. Also, it will be understood that the disadvantages of greater 
fluid consumption and unreliability of weft insertion would become a 
common phenomenon were a higher speed of the main and sub-fluid jets to be 
employed to increase the speed of weft insertion. 
As a weft guiding apparatus which would appear to remove the disadvantages 
in the afore-mentioned weft guiding apparatus, a weft guiding apparatus 
with no sub-nozzles has been provided, which comprises a number of weft 
guiding members each having a substantially circular aperture with a small 
opening formed in the upper portion of each weft guiding member. However, 
this weft guiding apparatus has not been favourably used, because the 
above-discussed disadvantage of the unreliability of weft insertion has 
not yet been eliminated. Since the opening provided in each weft guiding 
member is of a slit-like shape greatly narrowed to such an extent that the 
weft yarn barely escapes therefrom, a relatively high differential 
pressure will develop between the inside and outside of the channel 
defined by the apertures when the fluid is discharged into the channel 
from the main nozzle. This causes a speed of fluid escaping or leaking 
through the slit-like opening to be greatly increased and the leading end 
of the weft yarn may be entrained by the fluid flow escaping at an 
increased speed, thus coming out of the channel through the slit-like 
opening. Therefore, it is understood that although the weft guiding 
apparatus with no sub-nozzles is considered to be reasonably improved in 
fluid consumption, it is still not able to provide sufficiently good 
reliability of weft insertion, which is the most important characteristic 
required in a weft guiding apparatus. 
Then, in view of the above requirement, it has been attempted to provide 
each weft guiding member with an elastic tongue, which normally closes the 
inlet of the aperture's narrow opening, but, prior to the beating, opens 
the same by being deformed in terms of the inserted weft yarn to allow for 
the beating. Also, it has been attempted to provide each of the selected 
weft guiding members with a fluid passage, which has fluid outlets at 
positions circumferentially arranged around the aperture of the weft 
guiding member to supply a plurality of jets of fluid surrounding the 
fluid jet produced by the main nozzle. However, such attempts would 
involve additional disadvantages in that the weft guiding member is of a 
relatively complex construction and problems are encountered in the design 
of the elastic tongue and the fluid outlets, resulting in difficulties and 
increased costs in the manufacture thereof. 
Therefore, it will be readily understood that a weft yarn guiding apparatus 
has been required, which enables weft insertion to be accomplished without 
failure at a reduced rate of fluid consumption, and which can be 
manufactured at a reduced cost. 
SUMMARY OF THE INVENTION 
This invention generally relates to an apparatus for guiding a weft yarn 
when it is inserted into a shed, formed between lower and upper warp 
yarns, by a jet of fluid discharged from a main fluid nozzle positioned 
beside a jet loom. Such apparatus generally comprises a number of weft 
guiding members arranged in spaced relationship with each other and in 
parallel to a reed of the jet loom, the weft guiding members each having 
an aperture with an opening to allow the weft yarn to come out of the 
apertures after it has been inserted into the shed. A continuous weft 
guiding channel is provided by means of the apertures. 
According to this invention, the weft guiding members are composed of a 
first group of weft guiding members of which the openings are of a 
relatively narrow width and formed in upper parts of the first group of 
weft guiding members, and a second group of weft guiding members of which 
the openings are of a relatively broad width and formed in side parts of 
the second group of weft guiding members on the side of the reed, each of 
the second group of weft guiding members being interposed between adjacent 
two of the first group of weft guiding members with their apertures 
positioned in alignment with each other with respect to a direction in 
which the weft yarn is inserted. The apparatus further comprises 
sub-nozzles each having at least one fluid outlet discharging a jet of 
fluid to assist the fluid jet produced by the main nozzle in inserting the 
weft yarn into the shed, the fluid outlet being positioned substantially 
in alignment with the corresponding weft guiding member in the second 
group with respect to a direction of the warp yarn so as to face the broad 
opening of the aperture in the corresponding weft guiding member in the 
second group so that the fluid jet produced by the respective sub-nozzle 
is obliquely directed toward surfaces of the apertures in the first group 
of weft guiding members downstream of the associated sub-nozzle with 
respect to the direction in which the weft yarn is inserted, which 
surfaces are positioned away from the reed. This arrangement can 
effectively achieve the above object of this invention and enables high 
speed insertion of the weft yarn into the shed. 
In the preferred embodiments, the surfaces of the apertures in the first 
group of weft guiding members, toward which the fluid jet produced by the 
sub-nozzle is directed, extend substantially straight so as to more 
effectively prevent unexpected escape of the weft yarn from the channel.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now to FIG. 1, there is shown a beating apparatus incorporating a 
weft guiding apparatus according to this invention. As is known, the 
beating apparatus includes rockable slay swords 2 supporting a beam 1 
secured thereto by a suitable means, and a reed 3 mounted in a groove of 
the beam 1. The jet loom includes healds 5 to cause warp yarns 4 to form 
the shed, into which a weft yarn is to be inserted with a pneumatic 
picking mechanism including a main nozzle 9 (FIG. 2). 
In the groove of the beam 1, an elongated mounting bar 6 having a 
rectangular cross-section is also fixedly mounted in a suitable 
conventional manner to mount therein the weft guiding apparatus of this 
invention. For this purpose, the mounting bar 6 in its upper surface is 
provided with a longitudinally extending groove 6a, and a suitable number 
of holes 6c arranged in spaced relationship along the length of the groove 
6a and each being in fluid communication with a longitudinally extending 
fluid passage 6b formed in the mounting bar 6. The weft guiding apparatus 
includes a plurality of sub-nozzles 10 corresponding in number to the 
holes 6c and having their root portions fitted into the corresponding 
holes 6c. Each of the sub-nozzles 10 is in the form of a pipe with a 
closed sharp free end. The weft guiding apparatus, as clearly shown in 
FIG. 2, further includes an array of weft guiding members 7 and 7' fixedly 
mounted in the groove 6a by such means as a suitable adhesive 8. Apartures 
7a and 7a' are formed respectively in the weft guiding members 7 and 7' to 
provide a weft guiding channel 12, through which the weft yarn is inserted 
into the shed mainly by a jet of fluid, such as air, produced by the main 
nozzle 9. Each aperture converges toward the downstream side. 
As best shown in FIGS. 3 and 4, each of the weft guiding members 7' is 
positioned in alignment with the corresponding sub-nozzle 10 with respect 
to the direction of the warp yarn 4. It will be understood that between 
the weft guiding members 7' the plurality of weft guiding members 7 are so 
disposed that their apertures 7a are aligned with the apertures 7a' of the 
weft guiding members 7'. The sub-nozzle 10 has an outer diameter D smaller 
than the thickness L of at least the weft guiding member 7'. However, the 
outer diameter D may be equal to the thickness L. 
In FIGS. 5A and 5B, the weft guiding members 7 and 7' are shown on an 
enlarged scale. The weft guiding member 7' is of the rather "open" type 
wherein the aperture 7a' has a larger opening 7f' on the side of the reed 
3 (FIG. 1), while the weft guiding member 7 is of the rather "closed" type 
wherein the aperture 7a has a smaller opening 7f in the upper portion of 
the guiding member 7 on the side thereof facing the reed. The guiding 
member 7 is bifurcated into a first curved portion 7d and a second, 
substantially straight portion 7e, the free ends of these portions 7d and 
7e being close to each other forming the narrow opening 7f. As shown in 
FIG. 4, the second portion 7e is substantially in alignment with the 
sub-nozzle 10 with respect to the weft inserting direction. The aperture 
7a defined or surrounded by these portions 7d and 7e comprises 
substantially straightly extending or flat upper, inner, lower and outer 
surfaces 7g, 7h, 7i and 7j connected with each other by the curved 
surfaces. The weft guiding member 7' may be considered to correspond to 
the weft guiding member 7, from which the second portion 7e has been 
removed, and therefore its aperture 7a' is defined only by the first 
portion 7d and does not include the upwardly straightly extending flat 
surface 7j on the second portion 7e. 
FIGS. 6A and 6B show another embodiment of this invention, which 
substantially corresponds to the previous embodiment, except that each 
sub-nozzle 10 is so arranged as to position its fluid outlets 1Ob within 
the weft guiding channel 12. Therefore, it is apparent that the majority 
of the following description concerning weft guiding members 11 and 11' 
shown in FIGS. 6A and 6B is also applicable to the previous embodiment 
with the above exception. 
In FIG. 6A, the weft guiding member 11 is bifurcated into a first curved 
portion 11d and a second, substantially straightly extending portion 11e 
to form an aperture 11a therebetween, the free end of the first portion 
11d being extended over and close to that of the second portion 11e to 
form a narrow and curved slit-like opening 11f to allow the weft yarn to 
come out of the aperture 11a after it has been inserted into the shed. The 
inside of the first portion 11d is composed of an upper straightly 
extending surface 11g, which is substantially horizontal when the 
apparatus is in the weft inserting position, an inner straightly extending 
surface 11h connected through curved surface to the inner end of the upper 
surface 11g and substantially perpendicularly extending relative to the 
upper surface 11g, and a lower straightly extending surface 11i connected 
through a curved surface to the lower end of the inner surface 11h and 
inclined downward toward the outer end thereof. Thus, these surfaces 11g, 
11h and 11i are so arranged as to form a U-shape. The upper surface 11g 
is in obtuse-angled relationship with the curved narrow opening 11f. On 
the other hand, the outer straightly extending surface 11j on the inside 
of the second portion 11e is connected through a curved surface to the 
outer end of the lower surface 11i of the first portion 11d and extends 
upward while inclining inwardly toward the outer end of the upper surface 
11g. Since the lower surface 11i is inclined downwardly toward the lower 
end of the outer surface 11j which is, in turn, inclined inwardly toward 
the outer end of the upper surface 11g, the total length of the surfaces 
11i and 11j can be elongated. 
In FIG. 6B, the weft guiding member 11' comprises an arm portion 11d' 
having a configuration similar to that of the first portion 11d of the 
weft guiding member 11 and forming an aperture 11a'. In a position in 
which, if the guiding member 11' were the guiding member 11, the second 
portion 11e would be positioned, a sub-nozzle 10 is separately disposed so 
as to form a relatively narrow opening 11f' between the conical end of the 
sub-nozzle 10 and the free end of the arm portion 11d', the opening 11f' 
having a configuration substantially corresponding to that of the lower 
half of the opening 11f discussed with reference to guiding member 11. 
Since the configuration of the weft guiding member arm portion 11d' 
substantially corresponds to that of the first portion 11d of the weft 
guiding member 11, the arm portion 11d' also contains straight surfaces 
11g', 11h' and 11i closely resembling the above-mentioned surfaces 11g, 
11h and 11i of the weft guiding member 11. However, the lower surface 11i' 
terminates at a position close to the cylindrical surface of the 
sub-nozzle 10 and a neck 11k connecting the curved portion 11d' to the 
body of the weft guiding member 11' includes a surface 11k' extending in 
parallel to the sub-nozzle 10 with a very narrow spacing 11l therebetween. 
As shown in FIG. 6A, the sub-nozzle 10, disposed on the opened side of the 
aperture 11a' in alignment therewith with respect to the direction of the 
warp yarn as shown in FIG. 6B, is adapted to allow the fluid outlets 10b 
formed therein to be positioned slightly inside of the aperture 11a, i.e., 
inwardly of the outer surface 11j when looking in the direction of the 
weft insertion. 
Next, the operation of the above embodiments of the weft guiding apparatus 
will be described. 
In FIG. 1, the solid lines show the beating apparatus in the condition that 
one cycle of the beating operation has been completed. At that time, the 
weft guiding apparatus comprising the sub-nozzles 10 and the array of weft 
guiding members 7 and 7' is brought out of the shed formed by the warp 
yarns 4. When the rockable slay swords 2 turn back, or leftwardly in FIG. 
1, from the position shown by the solid lines, the healds 5 move 
vertically to cause the warp yarns 4 to form the shed again therebetween 
and the weft guiding apparatus enters the shed as shown by the dot and 
dash lines in FIG. 1. Then, the main nozzle 9 (FIG. 2) discharges the jet 
of fluid, by which the weft yarn is entrained and inserted into the 
continuous channel 12 formed by the apertures 7a and 7a' of the weft 
guiding members 7 and 7'. In the meantime, jets of fluid are also 
discharged from the sub-nozzles 10 to assist the main jet produced by the 
main nozzle 9 in feeding the weft yarn through the channel 12. 
It is again stated that the weft guiding apparatus of this invention 
comprises the weft guiding members 7' or 11' each having the aperture 7a' 
or 11a' of the rather "open" type greatly opened at the reed side thereof, 
the sub-nozzles 10 disposed on the reed side of the "open" type apertures 
7a' or 11a', and the weft guiding members 7 or 11 each having the aperture 
7a or 11a of the rather "closed" type slightly opened at the upper side 
thereof and positioned in alignment with the "open" type apertures 7a' or 
11a' with respect to the weft inserting direction. Also, the sub-nozzles 
10 are positioned to be aligned with the second arm portions 7e and 11e of 
the weft guiding members 7 and 11 with respect to the weft inserting 
direction. With the weft guiding apparatus as constructed above, when the 
weft yarn, entrained by the main jet of fluid produced by the main nozzle 
9, travels through the apertures 7 a and 7a' or 11a and 11', it is forced, 
by the jets of fluid produced by the sub-nozzles 10, toward the side of 
the inner surfaces 7h or 11h of the apertures 7a or 11a opposite to the 
openings 7f or 11f. Moreover, the sub-nozzles 10 and the second arms 7e or 
11e of the weft guiding members 7 or 11 serve to separate the apertures 
7a' and 11a' and 7a or 11a from the outside atmosphere, thereby preventing 
the fluid blown against and deflected by the inner surfaces 7h or 11h from 
directly coming out of the apertures. This contributes effectively to 
providing the jets of fluid produced by the sub-nozzles 10 with the 
important function of propelling the weft yarn in the weft inserting 
direction. Therefore, it is understood that the relatively high speed of 
fluid flow, which effectively contributes to the propulsion of the weft 
yarn, can be maintained in the region adjacent to the inner surfaces 7h 
and 7h' of the apertures 7a and 7a' or the inner surfaces 11h or 11h' of 
the apertures 11a and 11a' so that the weft yarn can be prevented from 
flying out from the apertures. This assures a stable and reliable 
insertion of the weft yarn. Also, since the propulsion of the fluid jets 
produced by the sub-nozzles can act sufficiently on the weft yarn, the 
efficiency of fluid utilization can be increased. This means that the weft 
yarn can be inserted into the shed with a lower consumption of fluid. 
Furthermore, as shown in FIGS. 5A and 5B or FIGS. 6A and 6B, at least each 
weft guiding member 7 or 11 has an aperture 7a or 11a, of which at least 
the inner surface 7h or 11h is formed in an substantially straightly 
extending or flat plane. The jet of fluid produced by the sub-nozzle 10 
and shown by the reference numerals 10a in FIGS. 4, 5A, 6A and 6B advances 
obliquely through the several apertures 7a or 11a in the weft guiding 
members 7 or 11 positioned downstream of the associated sub-nozzles 10 
with respect to the weft inserting direction until it strikes against the 
inner surface or surfaces 7h or 11h of the aperture or apertures 7a or 11a 
further downstream of the apertures 7a or 11a, through which the fluid jet 
10a has just advanced. Then, the fluid jet 10a is deflected by the inner 
surface 7h or 11h. However, since the inner surface 7h or 11h is formed 
flat as stated above, there is no fear that the deflected fluid is 
directed directly toward the opening(s) 7f or 11f of the aperture(s) 7 or 
11 positioned downstream of the aperture, by which the fluid jet 10a has 
been deflected, thereby assuring more reliable weft insertion and further 
reduced fluid consumption. 
It is further stated that although the reflected fluid may flow along the 
surfaces 7g and 7i or 11g and 11i to some extent toward the opening 7f or 
11f, even in this case, it is possible to minimize the amount of fluid 
escaping from the opening, because the surfaces 7g and 7i or 11g and 11i 
are also formed flat and accordingly cause no circularly swirling flow to 
occur in the weft guiding channel. Also, this explanation is applicable to 
any fluid, which is reflected by the surface 7j or 11j, because the latter 
is similarly formed flat. Thus, it can be understood that no swirling flow 
occurs through the weft guiding channel in the direction of the weft 
insertion, although a flow moving in a zigzag direction may be generated, 
and that the majority of the fluid flows close to the surfaces 7h and 7h' 
or 11h and 11h' in the weft inserting direction, thus limiting the leakage 
of fluid through the openings 7f and 7f' or 11f and 11f' to a minimum. 
Furthermore, according to this invention, each of the weft guiding members 
is so sized as to have a thickness L larger than or substantially equal to 
the outer diameter D of the sub-nozzle 10. If the thickness L of the weft 
guiding member were less than the sub-nozzle outer diameter D, there would 
be the fear that, when the weft guiding apparatus enters through the group 
of lower warp yarns, if any of the warp yarns, which extend beside the 
sub-nozzle and then between the adjacent weft guiding members, deviates 
from its normal path, it will be trapped in the aperture of the weft 
guiding member, resulting in a delayed formation of the shed and inviting 
failure of the weft insertion operation. However, according to this 
invention, since at least the weft guiding member 7' is in the 
above-stated dimensional relationship with the sub-nozzle, it will be 
apparent from FIG. 4 that the warp yarn 4 passing beside either of the 
diametrically opposite sides of the sub-nozzle 10 can be prevented from 
being trapped in the aperture 7a' of the weft guiding member 7'. Thus, 
reliable weft insertion can be assured. The more detailed explanation is 
that since the sub-nozzle 10 is positioned in alignment with the weft 
guiding member 7' with respect to the direction of the warp and its sharp 
end is below the upper end of the first curved portion 7d' of the weft 
guiding member 7', the warps 4 can be distributed to the opposite sides of 
the weft guiding member 7' by the upper end thereof when the weft guiding 
apparatus enters through the group of lower warp yarns. Therefore, the 
warp 4 extends beside either of the opposite sides of the weft guiding 
member 7' as shown in FIG. 4 and it is prevented from being trapped in the 
aperture 7a' of the weft guiding member 7'. 
In the case where the thickness L of the weft guiding member 7' is constant 
and larger than the inner diameter D of the sub-nozzle 10, there is little 
fear that the warp yarn 4 may be trapped in the aperture 7a' thereof. In 
order to remove this fear, as shown in FIG. 4, the weft guiding member 7' 
is preferably so shaped as to include parallel surfaces 7b', 7b' 
positioned remote from the sub-nozzle 10, and tapered surfaces 7c', 7c' on 
the sub-nozzle side and converging toward the sub-nozzle 10. The parallel 
surfaces 7b', 7b' serve to keeep the spacing between the guides 7 and 7' 
substantially constant so as not to cause a disturbance in the condition 
of the fluid flow flowing through the apertures, and the tapered surfaces 
7c', 7c' prevent the above-discussed trapping of the warp yarn 4 such as 
might cause erroneous weft insertion. The guide 7 may also include 
parallel surfaces 7b and tapered surfaces 7c. 
Although FIG. 4 illustrates an embodiment employing the weft guiding 
members 7 and 7', of which the thickness L is larger than the outer 
diameter D of the sub-nozzle 10, the thickness L may be exactly the same 
as the outer diameter D so as to facilitate the manufacturing of the weft 
guiding member 7'. In this case, even if the side surfaces 7c' of the weft 
guiding member 7' are not tapered, there will be no fear that the warp 
yarn 4 is caught in the aperture 7a'. Also, in this case, the tapered 
surfaces 7c of the guide 7 may be parallel surfaces 7c". 
In the embodiment shown in FIG. 4, all the weft guiding members 7 and 7' 
have the increased thickness L. The increase of the thickness of each weft 
guiding member necessarily reduces the spacing between the adjacent weft 
guiding members, so that the leakage of fluid can be further reduced. 
However, only the weft guiding member 7' facing the corresponding 
sub-nozzle 10 need be in the above-discussed dimensional relationship with 
the sub-nozzle. 
It will be apparent to those skilled in the art that the above discussion 
made in conjunction with FIG. 4 can be applied to the embodiment shown in 
FIGS. 6A and 6B. 
In the embodiment shown in FIGS. 6A and 6B, the fluid outlets 10b provided 
in the sub-nozzle 10 facing the weft guiding member 11' are arranged more 
inwards of the aperture 11a than the inside surface 11j of the second arm 
portion 11e of the weft guiding member 11. This arrangement allows the 
fluid jets 10a produced by the sub-nozzle 10 to blow in the apertures 11a 
without interference with the inside surface 11j of the second arm portion 
11e closely adjacent to the associated sub-nozzle 10. Thus, the fluid jets 
10a can act efficiently on the weft yarn being fed through the weft 
guiding channel. 
Although specific embodiments have been described above, it will be readily 
understood by those skilled in the art that numerous other arrangements, 
modifications and adaptations may be conceived without departing from the 
spirit and scope of the invention.