Weft transport nozzle for air jet looms

Abstract

To provide a weft conveying nozzle of an air-jet loom, capable of improving the thrust of weft.SOLUTION: In a weft conveying nozzle of an air-jet loom, each of two air guide surfaces 37 has an inner edge F1 located on the inner peripheral surface of a flow pass forming part 34 and extending so as to be dented toward the base end side of the flow pass forming part 34, and an outer edge F2 located on the outer peripheral surface of the flow pass forming part 34 and extending along the inner edge F1 on the base end side of the flow pass forming part 34 relative to the inner edge F1. The two air guide surfaces 37 are evenly disposed around the central axis L1 of the flow pass forming part 34.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a weft transport nozzle for an air jet loom. [Background technology]

[0002] In an air jet loom, the weft is inserted into the weft transport nozzle by the air jet action of the main weft insertion nozzle. The weft transport nozzle comprises a thread guide and an acceleration tube.

[0003] The thread guide defines a weft passage through which the weft is inserted, and includes a conical flow passage forming portion on the outlet side of the weft passage. The acceleration tube includes a conical flow passage defining portion surrounding the flow passage defining portion, and defines a traction passage forward of the exit of the weft passage in the weft insertion direction of the weft. An annular air passage is defined between the outer peripheral surface of the flow passage defining portion and the inner peripheral surface of the flow passage defining portion. The flow passage cross-sectional area of ​​the air passage decreases from the base end side toward the tip end side of the flow passage defining portion. This change in the flow passage cross-sectional area of ​​the air passage accelerates the air flowing out of the air passage.

[0004] The weft thread inserted into the weft passage passes through the traction passage in the acceleration tube, where it is accelerated by air from the air passage and carried along by the air.

[0005] In order to improve the propulsive force of the weft yarn in the traction passage, for example, a threading nozzle 80 disclosed in Patent Document 1 has a plurality of notches 82 at the tip of a thread guide 81, as shown in Figures 13 and 14. The notches 82 are formed so as to gradually narrow from the tip of the thread guide 81 toward a root end 82a, which is the base end. These notches 82 prevent the air flowing out of the air flow path 83 from suddenly expanding when it enters the traction passage 84. Preventing the sudden expansion of air inside the threading nozzle 80 prevents the generation of turbulence, thereby improving the propulsive force of the weft yarn. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 9-21035 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in the threading nozzle 80 of Patent Document 1, although the notch 82 prevents the air from expanding suddenly, the flow path cross-sectional area of ​​the air flow path 83 changes suddenly at the root end 82a of the notch 82. As a result, the air flow is disturbed near the root end 82a of the notch 82, and the air flows back toward the inside of the thread guide 81, which does not improve the propulsive force of the weft yarn sufficiently. [Means for solving the problem]

[0008] A weft transport nozzle for an air jet loom for solving the above problems comprises a thread guide that defines a weft passage through which a weft is inserted and that has a flow passage forming part on the outlet side of the weft passage, and an acceleration tube that has a flow passage defining part that surrounds the flow passage forming part and that defines a traction passage ahead of the outlet of the weft passage in the weft insertion direction of the weft, and an annular air passage is defined between an outer peripheral surface of the flow passage forming part and an inner peripheral surface of the flow passage defining part, and the air passage communicates with the traction passage at the outlet of the air passage and In a weft conveying nozzle of an air jet loom in which the cross-sectional area of ​​the flow path decreases toward the outlet of the flow path, the thread guide is provided with a plurality of air guide surfaces at the tip of the flow path forming portion, each of the plurality of air guide surfaces being located on the inner peripheral surface of the flow path forming portion and having an inner edge extending in a concave manner toward the base end side of the flow path forming portion, and an outer edge being located on the outer peripheral surface of the flow path forming portion and extending along the inner edge at a position closer to the base end side of the flow path forming portion than the inner edge, and the plurality of air guide surfaces being evenly arranged around the central axis of the flow path forming portion.

[0009] According to this, the air flowing out from the outlet of the air flow path into the traction passage is guided by the air guide surface toward the central axis of the traction passage. This prevents the air flowing out of the air flow path from flowing back into the weft passage toward the base end of the flow path forming portion. This prevents a decrease in the propulsion force of the weft yarn due to the backflow of air, thereby improving the propulsion force of the weft yarn. Furthermore, the evenly spaced air guide surfaces evenly distribute the air flowing out from the outlet of the air flow path into the traction passage into multiple flows. This reduces the magnitude of the shock waves generated by the air flowing out from the outlet of the air flow path. This prevents a decrease in the propulsion force of the weft yarn due to shock waves in the acceleration tube. Therefore, the evenly spaced air guide surfaces further improve the propulsion force of the weft yarn produced by the air injection action of the weft insertion main nozzle.

[0010] The weft transport nozzle of the air jet loom may be provided with two of the air guide surfaces. According to this, the fewer the number of air guide surfaces, the more easily the air that flows out from the outlet of the air flow path into the traction passage is dispersed. Therefore, by using two air guide surfaces, the magnitude of the shock wave generated by the air that flows out from the outlet of the air flow path can be further reduced.

[0011] In a weft conveying nozzle of an air jet loom, the two air guide surfaces may be arranged on either side of an imaginary line perpendicular to the central axis of the flow path forming section, and a cross section of the air guide surface along the central axis and perpendicular to the imaginary line may have a curved shape that bulges forward in the weft insertion direction from the base end side of the flow path forming section toward the imaginary line.

[0012] According to this, the air flowing out from the outlet of the air flow path is guided by the air guide surface so as to flow toward the central axis of the traction passage. [Effects of the Invention]

[0013] According to the present invention, the driving force of the weft yarn can be further improved. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 2 is a cross-sectional view showing a weft transport nozzle according to the embodiment. [Figure 2] FIG. 4 is a partial cross-sectional view showing the periphery of the air guide surface. [Figure 3] FIG. 2 is a partial perspective view showing an air guide surface. [Figure 4] FIG. 3 is a partial cross-sectional view showing a precursor and a flow path forming portion. [Figure 5] FIG. 10 is a partial cross-sectional view showing another example of an air guide surface. [Figure 6] FIG. 10 is a partial perspective view showing another example of an air guide surface. [Figure 7] FIG. 10 is a partial cross-sectional view showing another example of the air guide surface. [Figure 8] FIG. 10 is a partial perspective view showing another example of the air guide surface. [Figure 9] FIG. 10 is a partial cross-sectional view showing another example of the air guide surface. [Figure 10] FIG. 10 is a partial perspective view showing another example of the air guide surface. [Figure 11] FIG. 10 is a partial cross-sectional view showing another example of the air guide surface. [Figure 12] FIG. 10 is a partial perspective view showing another example of the air guide surface. [Figure 13] FIG. 1 illustrates the background art. [Figure 14] FIG. 10 is an enlarged view of the root end of the notch. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, one embodiment of a weft transport nozzle for an air jet loom will be described with reference to Figs. [Weft transport nozzle as a whole] Although not shown, in an air jet loom, the weft is inserted into a weft transport nozzle by the air jet action of a main weft insertion nozzle.

[0016] As shown in FIG. 1, the weft transport nozzle 10 includes a nozzle body 11, an acceleration tube 20, and a thread guide 30. <Nozzle body> The nozzle body 11 is cylindrical. A through-hole 12 is formed in the nozzle body 11, penetrating in the axial direction X of the nozzle body 11. The axial direction X of the nozzle body 11 is the direction in which the central axis of the nozzle body 11 extends. The nozzle body 11 has a first end surface 11a located at one end in the axial direction X, and a second end surface 11b located at the other end in the axial direction X. The nozzle body 11 has an internal thread 13 aligned in the axial direction X, a first demarcated surface 14, a second demarcated surface 15, and a stepped surface 16, as well as a connection port 17 extending in a direction intersecting the axial direction X.

[0017] The female thread 13 is formed between a first end face 11a on the inner circumferential surface of the nozzle body 11 and a first demarcated surface 14. The inner diameter of the nozzle body 11 at the first demarcated surface 14 is larger than the inner diameter of the nozzle body 11 at the second demarcated surface 15. The first demarcated surface 14 defines a large diameter hole 14a inside the nozzle body 11. The second demarcated surface 15 defines a small diameter hole 15a inside the nozzle body 11. A stepped surface 16 is formed at the boundary between the first demarcated surface 14 and the second demarcated surface 15. A connection port 17 opens toward the large diameter hole 14a. The connection port 17 connects the inside and outside of the nozzle body 11. An air supply pipe 18 is connected to the connection port 17.

[0018] <Acceleration tube> The accelerating structure 20 is cylindrical. The axial direction X of the accelerating structure 20 coincides with the axial direction X of the nozzle body 11. For this reason, the axial direction of the accelerating structure 20 will be referred to as the "axial direction X." The accelerating structure 20 includes a flow path defining portion 22 and a small-diameter cylindrical portion 23, which are aligned in the axial direction X. The outer diameter of the flow path defining portion 22 is larger than the outer diameter of the small-diameter cylindrical portion 23. The outer diameter of the flow path defining portion 22 is slightly smaller than the diameter of the large-diameter hole 14a. The outer diameter of the small-diameter cylindrical portion 23 is slightly smaller than the outer diameter of the small-diameter hole 15a. The flow path defining portion 22 is fitted inside the nozzle body 11 at the large-diameter hole 14a, and the small-diameter cylindrical portion 23 is fitted inside the nozzle body 11 at the small-diameter hole 15a. The boundary between the flow path defining portion 22 and the small-diameter cylindrical portion 23 contacts the step surface 16. This contact prevents the acceleration tube 20 from coming out of the nozzle body 11.

[0019] The accelerating structure 20 has a tapered inner circumferential surface 24 and a passage defining surface 25. The tapered inner circumferential surface 24 opens to an end face 20a of a flow path defining portion 22 in the accelerating structure 20. The inner diameter of the tapered inner circumferential surface 24 in the accelerating structure 20 decreases from the end face 20a toward the passage defining surface 25. The inner diameter of the passage defining surface 25 in the accelerating structure 20 is constant. Inside the accelerating structure 20, a traction passage 26 is defined by the passage defining surface 25. The passage diameter of the traction passage 26 is constant in the axial direction X. Furthermore, the central axis L of the traction passage 26 coincides with the central axis of the accelerating structure 20.

[0020] <Thread Guide> The thread guide 30 is cylindrical. The thread guide 30 defines a weft passage 30a through which the weft Y is inserted. The axial direction of the thread guide 30 coincides with the axial direction X of the nozzle body 11. For this reason, the axial direction of the thread guide 30 is referred to as the "axial direction X." The thread guide 30 includes a male thread 31 aligned in the axial direction X, a base 32, fins 33, a flow path forming portion 34, and multiple air guide surfaces 37. The male thread 31 is threaded into the female thread 13 of the nozzle body 11. The base 32 is cylindrical. The outer diameter of the base 32 of the thread guide 30 is slightly smaller than the diameter of the large diameter hole 14a. The outer peripheral surface of the base 32 contacts the first defining surface 14, and the base 32 is fitted inside the nozzle body 11 at the large diameter hole 14a.

[0021] The fins 33 are spaced apart from the base 32 in the axial direction X of the thread guide 30. The fins 33 are provided at equal intervals in the circumferential direction of the thread guide 30. The outer diameter of the fins 33 in the thread guide 30 is slightly smaller than the diameter of the large diameter hole 14a. The outer peripheral surface of the thread guide 30 at each fin 33 contacts the first defining surface 14, and each fin 33 is fitted inside the nozzle body 11 in the large diameter hole 14a.

[0022] As shown in FIGS. 1 and 2, the central axis L1 of the flow path forming portion 34 extends in the axial direction X. The flow path forming portion 34 has a conical cylindrical shape that becomes thinner with increasing distance from the fin 33 in the axial direction X. The outer diameter of the flow path forming portion 34 decreases with increasing distance from the fin 33 in the axial direction X. The inner diameter of the flow path forming portion 34 is constant in the axial direction X. Therefore, the thickness of the flow path forming portion 34 gradually decreases with increasing distance from the fin 33 in the axial direction X.

[0023] Most of the flow path forming portion 34 is inserted inside the flow path defining portion 22. Therefore, the acceleration structure 20 includes the flow path defining portion 22 that surrounds the flow path forming portion 34. An annular air flow path 50 is formed between the outer peripheral surface of the flow path forming portion 34 and the tapered inner peripheral surface 24 of the flow path defining portion 22.

[0024] Air supplied from the air supply pipe 18 flows into the air flow path 50. Specifically, the air supplied from the air supply pipe 18 into the nozzle body 11 is supplied between the base 32 and the fins 33 of the thread guide 30, and also passes between the fins 33 before being supplied to the air flow path 50. The pressure of the air supplied from the air supply pipe 18 is adjusted, thereby adjusting the pressure of the air flowing through the air flow path 50. The higher the pressure of the air supplied from the air supply pipe 18, the faster the flow rate of the air flowing through the air flow path 50 can be.

[0025] The air flow path 50 is a portion of the outer peripheral surface of the flow path forming portion 34 that extends from a position corresponding to the end face 20a of the accelerating structure 20 to the tip of the flow path forming portion 34. The air flow path 50 has an inlet 50a and an outlet 50b. The inlet 50a is defined between the outer peripheral surface of the flow path forming portion 34 and the tapered inner peripheral surface 24. The outlet 50b is defined between the tip of the flow path forming portion 34 and the tapered inner peripheral surface 24. The air flow path 50 communicates with the traction passage 26 at the outlet 50b of the air flow path 50.

[0026] The cross-sectional area of ​​the air flow path 50 gradually decreases from the inlet 50a toward the outlet 50b. Therefore, the air flow path 50 functions as a throttle at the outlet 50b. The throttle function of the air flow path 50 increases the flow rate of the air as it leaves the outlet 50b of the air flow path 50. The air flowing through the air flow path 50 is supplied to the traction passage 26 from the outlet 50b.

[0027] A weft passage 30a extending in the axial direction X is formed inside the thread guide 30. A weft Y is inserted through the weft passage 30a. The inlet of the weft passage 30a opens toward the first end face 11a of the nozzle body 11. The outlet of the weft passage 30a opens into the traction passage 26. Therefore, the thread guide 30 is provided with a flow passage forming portion 34 on the outlet side of the weft passage 30a. The acceleration tube 20 also defines the traction passage 26 forward of the outlet of the weft passage 30a in the weft insertion direction Z of the weft Y.

[0028] The weft passage 30a is connected to the traction passage 26. A weft Y is inserted into the weft passage 30a by the air injection action of a weft insertion main nozzle (not shown). The weft Y inserted into the weft passage 30a travels in the weft insertion direction Z. The weft Y travels through the traction passage 26 ahead of the exit of the weft passage 30a in the weft insertion direction Z. The weft Y is accelerated by the air from the air flow path 50 and is carried along by the air flow. This provides a propulsive force to the weft Y.

[0029] <Air guide surface> 2, 3, and 4, two air guide surfaces 37 are provided at the tip of the flow path forming portion 34. Each of the two air guide surfaces 37 has an inner edge F1 and an outer edge F2.

[0030] A pair of inner circumferential ends T1 are present at the tip of the flow path forming portion 34. The pair of inner circumferential ends T1 are located on the inner peripheral edge of the flow path forming portion 34. In addition, a pair of outer circumferential ends T2 are present at the outer peripheral edge of the flow path forming portion 34. The inner circumferential end T1 and the outer circumferential end T2 are located at the boundary between the two air guide surfaces 37.

[0031] The flow passage forming portion 34 is formed with two leading edges 36 connecting the inner peripheral end T1 and the outer peripheral end T2. Each leading edge 36 connects the inner peripheral end T1 and the outer peripheral end T2 in the radial direction of the flow passage forming portion 34. When an imaginary line G passing through the leading edges 36 is extended in the radial direction of the flow passage forming portion 34, the imaginary line G is perpendicular to the central axis L of the traction passage 26. Two leading edges 36 are formed at the tip of the flow passage forming portion 34. The two leading edges 36 are located at the boundaries between two air guide surfaces 37. The air guide surfaces 37 including the leading edges 36 are inclined with respect to the weft insertion direction Z.

[0032] The inner edge F1 is located on the inner circumferential surface of the flow channel forming portion 34. The inner edge F1 is a curve connecting the pair of inner circumferential ends T1 in the circumferential direction of the flow channel forming portion 34. The inner edge F1 is an opening edge extending along the outlet of the weft passage 30a. The inner edge F1 extends in an arc-like recess toward the base end of the flow channel forming portion 34. The outer edge F2 is located on the outer circumferential surface of the flow channel forming portion 34. The outer edge F2 is a curve connecting the pair of outer circumferential ends T2 in the circumferential direction of the flow channel forming portion 34. The outer edge F2 extends in the circumferential direction of the flow channel forming portion 34 along the inner edge F1 on the base end side of the flow channel forming portion 34 relative to the inner edge F1. Each air guide surface 37 is formed on a surface connecting the inner edge F1 and the outer edge F2. More specifically, each air guide surface 37 is a surface surrounded by the pair of tip edges 36, the inner edge F1, and the outer edge F2.

[0033] Therefore, each of the two air guide surfaces 37 has an inner edge F1 that extends concavely toward the base end side of the flow path forming portion 34, and an outer edge F2 that is located on the outer peripheral surface of the flow path forming portion 34 and extends along the inner edge F1 on the base end side of the flow path forming portion 34 rather than the inner edge F1.

[0034] The point on the outer edge F2, which is the midpoint between the two outer peripheral ends T2, is defined as the midpoint FP. The plane on which the two inner peripheral ends T1 are located and which is perpendicular to the central axis L1 of the flow path forming portion 34 is defined as the tip imaginary plane N1. The plane passing through the two inner peripheral ends T1 and the midpoint FP is defined as the imaginary plane H. The imaginary plane H intersects obliquely with the tip imaginary plane N1. Because there are two inner peripheral ends T1 in the flow path forming portion 34, there are also two midpoints FP in the flow path forming portion 34. Therefore, two imaginary planes H are formed in the flow path forming portion 34. The two imaginary planes H intersect with the tip imaginary plane N1 at an inclination angle θ. In the flow path forming portion 34, an air guide surface 37 is formed along each imaginary plane H.

[0035] The air guide surface 37 is a surface inclined at an inclination angle θ with respect to the tip imaginary plane N1. The dimension connecting the two inner circumferential ends T1 in the circumferential direction of the flow path forming portion 34, i.e., the length of the inner edge F1, is defined as the inner edge length of the air guide surface 37. The inner edge lengths of the two air guide surfaces 37 are equal. The dimension connecting the two outer circumferential ends T2 in the circumferential direction of the flow path forming portion 34, i.e., the length of the outer edge F2, is defined as the outer edge length of the air guide surface 37. The outer edge lengths of the two air guide surfaces 37 are equal. In other words, the two air guide surfaces 37 have the same dimension in the circumferential direction of the flow path forming portion 34. Therefore, the two air guide surfaces 37 are evenly spaced around the central axis L1 of the flow path forming portion 34. In other words, the air guide surfaces 37 are evenly spaced around the central axis L1 without any bias.

[0036] As shown by the two-dot chain line in Figure 4, the material before the air guide surface 37 is formed is referred to as precursor 90. The precursor 90 has a conical cylindrical shape in which the outer and inner peripheral surfaces of the flow path forming section 34 each extend toward a tip imaginary plane N1. The central axis of the precursor 90 is also the central axis L1 of the flow path forming section 34, and is therefore referred to as the "central axis L1 of the precursor 90." The inner diameter of the precursor 90 is constant in the axial direction X, and the outer diameter of the precursor 90 gradually decreases from the base end side to the tip side of the precursor 90.

[0037] Two inner circumferential ends T1 are set on the tip imaginary plane N1 of the precursor 90. The two inner circumferential ends T1 are set on the inner circumferential edge of the precursor 90 and are set at positions radially opposite each other from the flow passage forming portion 34. A midpoint FP is set on the outer circumferential surface of the precursor 90 closer to the base end than the tip imaginary plane N1. In a cross section of the precursor 90 taken along the central axis L1, the midpoint FP is the intersection of an imaginary plane H inclined at an inclination angle θ with respect to the tip imaginary plane N1 and the outer circumferential surface of the precursor 90. Two midpoints FP are set on the outer circumferential surface of the precursor 90. The precursor 90 is then cut along the imaginary plane H so as to pass through the midpoint FP and the two inner circumferential ends T1, thereby forming air guide surfaces 37. Each air guide surface 37 is inclined from the outlet side of the weft passage 30a toward the inlet side of the weft passage 30a.

[0038] [Operation of the embodiment] The weft Y passing through the weft passage 30a of the thread guide 30 and the traction passage 26 of the acceleration tube 20 receives a propulsive force due to the air injection action of the weft insertion main nozzle in the traction passage 26, which is located forward of the air guide surfaces 37 in the weft insertion direction Z. The air flowing out of the outlet 50b of the air flow path 50 is guided by the air guide surfaces 37 to flow toward the central axis L of the traction passage 26. Furthermore, the air around the outlet of the weft passage 30a does not flow concentrically with the annular air flow path 50, but is evenly dispersed into two streams by the air guide surfaces 37. This reduces the magnitude of shock waves generated in the acceleration tube 20 by the air flowing out of the outlet 50b of the air flow path 50. Furthermore, because the two air guide surfaces 37 are evenly spaced around the central axis L1, the air flows evenly without being biased in the circumferential direction of the flow path forming portion 34.

[0039] [Effects of the embodiment] According to the above embodiment, the following effects can be obtained. (1) The air guide surfaces 37 can prevent the air flowing out of the air flow path 50 from flowing back into the weft passage 30a toward the base end of the flow path forming portion 34. This can prevent a decrease in the propulsion force of the weft yarn Y caused by the backflow of air, thereby further improving the propulsion force of the weft yarn Y. In addition, the two evenly spaced air guide surfaces 37 can reduce the magnitude of shock waves generated by the air flowing out from the outlet 50b of the air flow path 50. This can prevent a decrease in the propulsion force of the weft yarn Y caused by shock waves. Therefore, the two evenly spaced air guide surfaces 37 can further improve the propulsion force of the weft yarn Y due to the air injection action of the weft insertion main nozzle. Furthermore, since there is no need to increase the pressure supplied to the air flow path 50 to improve the propulsion force of the weft yarn Y, it is also possible to prevent an increase in energy consumption for increasing the pressure.

[0040] (2) Two air guide surfaces 37 are provided at the tip of the flow path forming portion 34. The fewer the number of air guide surfaces 37, the less likely it is that the air flowing out of the air flow path 50 will flow concentrically forward in the weft insertion direction Z from the outlet of the weft passage 30a. Therefore, the two air guide surfaces 37 can further reduce the magnitude of the shock wave. As a result, the propulsion force of the weft Y can be further improved.

[0041] (3) The air guide surface 37 can reduce the magnitude of shock waves generated by the air flowing out from the outlet 50b of the air flow path 50. This can prevent the air flowing out from the air flow path 50 from adversely affecting the weft yarn Y, and can also prevent the weft yarn Y from unraveling if the weft yarn Y is a filament yarn.

[0042] (4) The air guide surface 37 can guide the air flowing out of the air flow path 50 toward the central axis L of the traction passage 26. Therefore, the weft yarn Y travels along the central axis L of the traction passage 26. As a result, the weft yarn Y can be prevented from colliding with the inner circumferential surface of the acceleration tube 20, and therefore, deterioration in the quality of the weft yarn Y can be prevented.

[0043] This embodiment can be modified as follows: This embodiment and the following modifications can be combined and implemented within the scope of technical compatibility. 5 and 6, three air guide surfaces 37 may be provided at the tip of the flow path forming portion 34. In this case, each of the three air guide surfaces 37 has an inner edge F1 and an outer edge F2. Three inner circumferential edges T1 are provided at the tip of the flow path forming portion 34. The three inner circumferential edges T1 are arranged at 120-degree intervals in the circumferential direction of the flow path forming portion 34.

[0044] Furthermore, three tip edges 36 are provided at the tip of the flow path forming portion 34. When an imaginary line G passing through each tip edge 36 is extended in the radial direction of the flow path forming portion 34, the imaginary line G intersects obliquely with the central axis L of the traction passage 26.

[0045] Although not shown, three imaginary surfaces H are formed. The three imaginary surfaces H intersect with the tip imaginary surface N1 at an inclination angle θ. At the tip of the flow path forming portion 34, an air guide surface 37 is formed along each imaginary surface H. The air guide surface 37 is a surface that is inclined at an inclination angle θ with respect to the tip imaginary surface N1. The three air guide surfaces 37 have the same circumferential length. Therefore, the three air guide surfaces 37 are evenly spaced around the central axis L1.

[0046] 7 and 8, eight air guide surfaces 37 may be provided at the tip of the flow path forming portion 34. In this case, each of the eight air guide surfaces 37 has an inner edge F1 and an outer edge F2. Eight inner circumferential edges T1 are provided at the tip of the flow path forming portion 34. The eight inner circumferential edges T1 are arranged at 45-degree intervals in the circumferential direction of the flow path forming portion 34.

[0047] Furthermore, eight tip edges 36 are provided at the tip of the flow path forming portion 34. When an imaginary line G passing through each tip edge 36 is extended in the radial direction of the flow path forming portion 34, the imaginary line G intersects the central axis L of the traction passage 26 obliquely.

[0048] Although not shown, eight imaginary surfaces H are formed. The eight imaginary surfaces H intersect with the tip imaginary surface N1 at an inclination angle θ. At the tip of the flow path forming portion 34, an air guide surface 37 is formed along each imaginary surface H. The air guide surface 37 is a surface that is inclined at an inclination angle θ with respect to the tip imaginary surface N1. The eight air guide surfaces 37 have the same circumferential length. Therefore, the eight air guide surfaces 37 are evenly spaced around the central axis L1.

[0049] The number of inner edges F1 and outer edges F2 provided on the flow path forming portion 34 may be changed as needed, and the number of air guide surfaces 37 may be changed as needed. 9 and 10, the two air guide surfaces 37 are disposed on either side of an imaginary line B that is perpendicular to the central axis L1 of the flow passage forming portion 34. The cross section of the air guide surface 37 along the central axis L1 and perpendicular to the imaginary line B is a curved surface that bulges forward in the weft insertion direction Z from the base end side of the flow passage forming portion 34 toward the imaginary line B.

[0050] According to this, the air flowing through the air flow path 50 is guided by the air guide surface 37 so as to flow smoothly toward the central axis L1 of the flow path forming portion 34 and the central axis L of the traction passage 26. Therefore, the generation of turbulence can be suppressed.

[0051] 11 and 12, the two air guide surfaces 37 are provided on either side of an imaginary line B perpendicular to the central axis L1 of the flow path forming portion 34. The cross section of the air guide surface 37 along the central axis L1 and perpendicular to the imaginary line B may have a shape in which, as it moves from the base end side of the flow path forming portion 34 toward the imaginary line B, a curved surface that is recessed rearward in the weft insertion direction Z and a curved surface that bulges forward in the weft insertion direction Z are continuous.

[0052] The inclination angle of the air guide surface 37 may be changed as needed. [Explanation of symbols]

[0053] B...imaginary line, F1...inner edge, F2...outer edge, L, L1...central axis, Y...weft, Z...weft insertion direction, 10...weft conveying nozzle, 20...acceleration tube, 22...flow path defining portion, 26...traction passage, 30...thread guide, 30a...weft passage, 34...flow path forming portion, 37...air guide surface, 50...air flow path, 50a...inlet, 50b...outlet.

Claims

1. a thread guide defining a weft passage through which a weft is passed and including a flow path forming portion on an outlet side of the weft passage; a flow path defining section surrounding the flow path forming section, and an acceleration tube defining a traction path forward of an outlet of the weft passage in the weft insertion direction of the weft, an annular air flow path is defined between an outer circumferential surface of the flow path forming portion and an inner circumferential surface of the flow path defining portion; a weft conveying nozzle for an air jet loom, wherein the air flow path communicates with the traction passage at an outlet of the air flow path, and a cross-sectional area of ​​the air flow path decreases from the inlet of the air flow path toward the outlet of the air flow path, The thread guide has a plurality of air guide surfaces at a tip of the flow path forming portion, Each of the plurality of air guide surfaces is an inner edge located on an inner circumferential surface of the flow path forming portion and extending so as to be recessed toward a base end side of the flow path forming portion; an outer edge located on an outer peripheral surface of the flow path forming portion and extending along the inner edge on a base end side of the flow path forming portion relative to the inner edge, 10. A weft transport nozzle for an air jet loom, wherein the plurality of air guide surfaces are evenly spaced around a central axis of the flow path forming portion.

2. 2. The weft transport nozzle for an air jet loom according to claim 1, wherein the nozzle comprises two air guide surfaces.

3. 3. The weft transport nozzle for an air jet loom according to claim 2, wherein the two air guide surfaces are disposed on opposite sides of an imaginary line perpendicular to the central axis of the flow path forming section, and a cross section of the air guide surface along the central axis and perpendicular to the imaginary line has a curved shape that bulges forward in the weft insertion direction as it moves from the base end side of the flow path forming section toward the imaginary line.

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