BACKGROUND OF THE INVENTION 
     This invention relates to a weft guide device in a jet loom. 
     Heretofore, in order to allow a weft to be smoothly inserted through the warp shed of a jet loom by flow of air discharged from a main nozzle arranged in a known manner, a weft guide device has been provided which comprises a number of weft guide members arranged near the reed in line with each other in the weft insertion direction, the weft guide members each being provided, for example on the side of the reed, with interiorly facing surfaces providing either a large weft guide opening (hereinafter referred to as the open type) or a small weft guide opening (hereinafter referred to as the closed type) sufficiently narrow to just allow the escapement of the weft therethrough, these surfaces being in alignment with each other to provide a weft guide path, and a suitable number of air discharge sub-nozzles arranged in predetermined locations along the weft guide path so that air outlets formed therein face the weft guide path. In this weft guide device, each of the sub-nozzles discharges a jet of air assisting the air jet from the main nozzle in carrying out the weft insertion; otherwise the leading end of the weft will not be able to be moved far enough during the weft inserting operation. 
     However, the weft guide device employing the open type weft guide members encounters the problems that because of the large openings provided by the respective weft guide surfaces of the guide members, the air discharged from the main and sub-nozzles is apt to easily escape through the large openings, resulting in a larger air consumption; and that during the weft inserting operation, the leading end of the weft may be entrained in the air currents escaping through the openings and erroneously moved out of the weft guide path. 
     In the weft guide device employing the closed type guide members, the weft insertion can not rely on the main nozzle alone when inserting through a relatively long weft guide path. Thus, some of the weft guide members arranged in the predetermined positions are formed into a hollow structure with an air passage therein and air outlet or outlets facing the weft guide path so that the pressurized air supplied to the air passage is discharged through the outlet or outlets into the weft guide path. However, since these hollow members require that the air passage and outlet(s) be formed therein while maintaining them in a shape similar to the remaining weft guide members, it is difficult to conform the size or dimensions of the hollow members to the remaining weft guide members. For example, the small opening, provided in the concave of each hollow member to allow the weft to escape from the weft guide path after the weft insertion, becomes inconsistent in position with the small openings in the remaining weft guide members. This may result in the failure of the weft insertion. Furthermore, it is difficult to ensure that the air outlet is so opened that the air flow therethrough is directed in the predetermined direction allowing the air flow to attain its object of assisting the main nozzle. This results in a critical disadvantage directly affecting the weft inserting function of the guide device. Thus, it is understood that the guide device employing the closed type guide members requires highly advanced manufacturing technology. 
     For these reasons, Japanese laid-open patent specification No. 55-128,047 has proposed a combined weft guide device including, as shown in FIGS. 1(A) and 1(B) hereof, both open type guide members 2 each having a concave shaped interior surface 1 with a large opening 5 on the left-hand side thereof, and closed type guide members 4 each having an interior surface 3 providing a small opening 6, in order to positively utilize the advantages of the open and closed type guide members. In this combined device, guide members 2 (FIG. 1(B)) are deliberately scattered throughout the array of guide members 4 (FIG. 1(A)) with their respective concaved surfaces 1 and 3 arranged in line. The weft escape openings 5 and 6 are formed on the side of a reed 12 as can be seen in FIG. 2. In front of the escape opening 5 of each guide member 2, a vertical sub-nozzle 19 (FIG. 2) is arranged to provide an auxiliary flow of air, and the weft escape opening 6 is provided on the side of the reed and in the upper part of concaved surface 3 between first and second arms 7 and 8 of weft guide member 4. 
     This combined guide device can prevent to some degree a great loss of discharged air accompanied by a weft insertion error. Also, this combined guide device does not require that an air passage be formed in any of the weft guide members and therefore can eliminate the difficulty in manufacturing the weft guide members. 
     However, in the combined guide device described above, as shown in FIG. 1(A), the second arm 8 of guide member 4 has an inner wall surface 3d (defining the rear wall of the surface 3) extending substantially straight upward to define opening 6. The substantially straight surface 3d can not cause the air discharged into the weft guide path to be effectively and satisfactorily converged during the weft inserting operation. Therefore, the air flow in the weft guide path is apt to branch away to the weft escape openings 5 and 6. This causes not only an increased air consumption, but also an unexpected movement of the weft through the openings out of the weft guide path entrained in the branch air flow, resulting in the failure of the weft insertion. In other words, the air flow discharged from the sub-nozzle is blown against the fore wall surface 3a of the concaved surface 3 and thereafter a portion thereof flows along the lower wall surface 3c toward the rear of the jet loom (the side of the second arm 8) and then upwardly along the rear wall surface 3d toward opening 6. Thus, said portion of the air flow is discharged out of the weft guide path through opening 6 and causes the failure of the weft insertion. 
     Accordingly, it is a primary object of this invention to provide a weft guide device for a jet loom, which, in order to eliminate the disadvantages of the prior art, can effectively use main and auxiliary air flows to decrease power consumption, allows easy manufacture of weft guide members, and enables a weft to pass through a weft guide path in a stable state to increase the speed of a weft insertion and cause the leading end of the weft to travel a longer distance, resulting in increased width in high speed jet looms. 
     SUMMARY OF THE INVENTION 
     With this object in view, the present invention resides in a weft guide device in a jet loom having a reed carrier for carrying a reed thereon, said device comprising an array of weft guide members mounted on said reed carrier along the reed, each of said guide members having interiorly facing surface to provide a weft guide path, said surface being provided in its upper portion with a relatively narrow opening to allow a weft to move therethrough out of said guide path in preparation for the beating by said reed, and air discharge members spacedly disposed in said guide member array and on the side of said opening to discharge air flows into said guide path, said interiorly facing surface being defined by surfaces including a substantially vertically extending surface having a curved upper portion joining with said opening, to direct air which is moving upwardly therealong towards a surface opposite said substantially vertically extending surface. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will become more readily apparent from the following description of a preferred embodiment thereof shown, by way of example only, in the accompanying drawings, wherein: 
     FIGS. 1(A) and (B) show side elevational views of the prior weft guide members; 
     FIG. 2 is a side elevational view showing a beating apparatus including a weft guide device made in accordance with this invention; 
     FIG. 3(A) is an enlarged fragmentary side elevation of a weft guide member according to the present invention; and FIG. (B) is a similarly enlarged fragmentary side elevation of an open-type weft guide member which is used with the weft guide member of FIG. 3(A) in accordance with an alternative embodiment of the insertion. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 2, there is shown a beating apparatus comprising a reed carrier 11 having a reed 12 mounted thereon. A number of weft guide members 13a, 13b are spacedly mounted on the carrier 11 in parallel with the reed 12. 
     Referring to FIGS. 2 and 3, each of the guide members 13a and 13b includes interior facing surfaces 14 or 15 forming a weft guide opening 16 of the guide member. The surfaces 14 and 15 are arranged in line with other. The surface 14 is formed only by a curved arm 17 of the weft guide 13a so that it has a large opening 18 on the rearward side of the reed 12. The surface 14 is defined by three wall surfaces 14a, 14b and 14c. As shown in FIG. 2, a substantially vertically disposed sub-nozzle 19 is mounted on the reer carrier opposite the opening 18. The surface 15 of the other guide member 13b is formed defined by a first arm 20 corresponding in shape to the arm 17 of the guide member 13a, and a second arm 21 branching off the first arm 20 so as to be in line with the sub-nozzle 19 with respect to the direction of a weft insertion. The free ends of, the first and second arms 20 and 21 approach each other to provide a relatively small weft thread opening 22 therebetween. The weft inserted through the weft guide path formed by the aligned weft guide openings 16 is adapted to move thereout of through the openings 18 and 22 before the beating. 
     The width of the opening 22 in the direction perpendicular to the end surfaces of the free ends of the first and second arms 20 and 21 is narrow as shown and the opening 22 extends upwardly with the same width along its entire length. 
     The interior surface 15 of the guide member 13b is defined by four conjoining wall surfaces 15a, 15b, 15c and 15d to provide the quadrilaterally shaped weft guide opening 16. A first arm 20 of the guide member 13b provides the upper and lower wall surfaces 15b and 15c, and the surface 15a positioned towards the forward end of the loom, while the second arm 21 provides the substantially vertical wall surface 15d positioned towards the rear of the loom. The rear wall surface 15d of the guide member 13b is in communication with the opening 22 with its upper portion 15d&#39; being curved forward (toward the end of the upper wall surface 15b). The curved upper portion 15d&#39; serves to smoothly guide the air flow, which ascends along the rear wall surface 15d, toward a space below the upper wall surface 15b without allowing it to flow into the opening 22. 
     The operation of the above guide device will be described as follows: 
     The solid lines in FIG. 2 show the condition immediately after the beating, under which the sub-nozzles 19 (only one thereof is illustrated) and the guide members 13a and 13b have moved out of the shed formed by warps Y. When the reed carrier 11 moves from the position shown by the solid lines toward the rear of the loom into the position shown by the phantom lines while healed frames not shown move vertically to form a new shed, the sub-nozzles 19 and the guide members 13a, 13b enter the new shed as shown by the phantom lines in FIG. 2. Then, in timed relationship with such a movement of the guide device, a not shown main nozzle discharges a main flow of air in which the leading end of the weft is entrained and inserted through the weft guide path formed by the openings 16 of the guide members 13a and 13b. Also, each sub-nozzle 19 discharges an auxiliary air flow in the known manner to assist the main air flow in performing the weft insertion. The auxiliary air from the sub-nozzle 19 is discharged toward the fore wall surfaces 15a of the guide member 13b positioned downstream of said sub-nozzle 19 with respect to the direction of the weft insertion. That is, the auxiliary air flow is discharged obliquely with respect to the direction of the weft insertion. Thus, when the leading end of the weft as well as the main air flow entraining same goes across the auxiliary air flow, it is subject to, in addition to the propulsive force acting in the direction of the weft insertion, a force positively forcing the weft toward the fore wall surfaces 15a of the weft guide path formed by opening 16. This means that all of the air flowing within the weft guide path has a tendency to proceed toward the wall surface 15a, that is, away from the openings 22. 
     A portion of the air flow which is blown against the wall surface 15a descends and passes along the lower wall surface 15c and then ascends the rear wall surface 15d toward the opening 22. However, there is little air entering the opening 22 because of the presence of the curved upper portion 15d&#39;, which smoothly guides the ascending air towards the upper wall surface 15b. Thus, it is understood that air escape through the opening 22 can be prevented, resulting in the prevention of weft insertion errors. 
     Furthermore, any flow of air toward the opening 22 will be positively directed toward the lower portion of the fore wall surface 15a of the associated weft guide member 13b by the auxiliary air flow from the sub-nozzle 19 positioned upstream of said weft guide member 13b. Thus, the auxiliary air flows discharged from the sub-nozzles 19 disposed in the predetermined locations throughout the width of the loom successively act on the main air flow discharged into the weft guide path by the main nozzle, so that the resulting air flow flows on the side of the wall surfaces 14a and 15a, although it slightly vibrates between the opening side and the fore wall surface side, that is, it flows in the zigzag direction to a certain degree, while moving through the guide path. 
     Therefore, it will be understood that the weft guide device of this invention increases the efficiency of air utilization because the amount of air flowing out through the openings 18 and 22 is reduced to as little as possible. This results in greatly decreased power consumption. Furthermore, since the air flow in the weft guide path effectively flows in a stable state, the leading end of the weft also travels in a stable state, resulting in an increased speed of the weft insertion. Furthermore, in this embodiment, the width of the opening 22 thereacross is narrow and remains the same from the lower to the upper end, the weft escape and the flowing out of the air through the opening 22 being able to be positively prevented. 
     Although in the above-discussed embodiment, the guide members 13a each having the interior surface 14 provided with the large opening on the reed side have been mounted in the positions opposite to the sub-nozzle 19, these guide members 13a are not always necessary and may be removed. That is, only the sub-nozzle need be provided between the adjacent guide members 13b. In this case, the guide device employs only a single kind of guide member, which makes the manufacture thereof easy. 
     It will be understood from the foregoing that since the upper portion 15d&#39; of the rear wall surface 15d defining the weft guide opening 16 is curved in the forward direction according to this invention, the effluence of the air through the openings 22 during the weft insertion can be prevented to the utmost. This increases the efficiency of the air utilization in the weft guide device, resulting in the reduced power consumption. Furthermore, as the result of the increase in the efficiency of the air utilization, the most important factors affecting the weft inserting function of the guide device, i.e., the stabilization and the speed-up of the weft movement in the guide path, can be greatly improved. It is of course true that the manufacturing of the guide members is made easy. It is further true that in a jet loom, since the weft was moved through the weft guide path only by the air flow and therefore its movement was relatively unrestrained, it was difficult to provide a wide jet loom. However, according to this invention, a wide jet loom can be realized because of the decreased power consumption and the improved weft inserting function as discussed above.
A weft guide device in a jet loom having a reed carrier for carrying a reed thereon is disclosed. The guide device made according to this invention generally comprises an array of weft guide members mounted on said reed carrier along the reed and each having a concave to provide a weft guide path, said concave being provided with a relatively narrow opening and defined by surfaces including a substantially vertically extending surface joining with said opening, and a surface opposite said substantially vertically extending surface through said concave. 
     According to this invention, the upper portion of said substantially vertically extending surface is curved toward said opposite surface.