Hook shaft drive mechanism of sewing machine

Abstract

To achieve a hook shaft drive mechanism of a sewing machine, which causes less vibration.SOLUTION: A bottom end 20b side of a crank rod 20 and a first gear 30 are connected through a connection member 60 in a hook shaft drive mechanism 1 of a sewing machine. The bottom end 20b side of the crank rod 20 and the connection member 60 are connected in a structure in which the bottom end 20b side of the crank rod 20 supports a shaft of the connection member 60 by holding both ends of the shaft. The connection member 60 and the first gear 30 are connected in a structure in which the connection member 60 supports a shaft of the first gear 30 by holding both ends of the shaft. As the shaft of the connection part at which power is transmitted from the crank rod 20 to the first gear 30 is supported by being held at both ends, unbalanced load at the connection part is suppressed so as to achieve well balanced connection structure in which balance of power is maintained. Consequently, vibration occurring at the connection part can be suppressed and occurrence of noise can be suppressed.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a shuttle shaft drive mechanism for a sewing machine. [Background technology]

[0002] Conventionally, there has been known a hook shaft drive mechanism for a sewing machine in which the upper end of a crank rod is connected to an upper shaft via an eccentric cam, a pendulum gear is connected to the lower end of the crank rod via a pendulum pin, and the pendulum gear is in mesh with a hook shaft gear disposed on the hook shaft (see, for example, Patent Document 1). The shuttle shaft drive mechanism of this sewing machine is designed so that when the upper shaft rotates, the crank rod swings up and down, causing the pendulum gear to swing and rotate, and the pendulum gear swings and rotates the shuttle shaft. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-236282 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the shuttle shaft drive mechanism of the sewing machine disclosed in Patent Document 1 has a problem in that vibrations tend to occur at the connecting points of the pendulum gear, etc. Furthermore, the vibrations can sometimes cause noise.

[0005] SUMMARY OF THE INVENTION An object of the present invention is to provide a hook shaft drive mechanism for a sewing machine that suppresses the generation of vibrations. [Means for solving the problem]

[0006] In order to solve the above problems, the invention described in claim 1 is as follows: a crank rod whose upper end is connected to a crankshaft provided eccentrically on an upper shaft rotated by a driving means; a first gear that rotates reciprocally due to the reciprocating movement of the lower end of the crank rod; a second gear that meshes with the first gear; a hook shaft that is oscillated and rotated by the second gear; A hook shaft drive mechanism for a sewing machine, comprising: The lower end side of the crank rod and the first gear are connected by a connecting structure in which either the lower end side of the crank rod or the first gear is supported by the other in a double-supported state.

[0007] The invention described in claim 2 is the hook shaft drive mechanism for a sewing machine described in claim 1, The connecting structure is a bifurcated portion formed on the lower end side of the crank rod; and a shaft member supported by the forked portion in a state of being supported at both ends.

[0008] The invention described in claim 3 is the hook shaft drive mechanism for a sewing machine described in claim 1, The connecting structure is a bifurcated portion that rotates back and forth integrally with the first gear; and a shaft member supported by the forked portion in a state of being supported at both ends.

[0009] The invention described in claim 4 is the hook shaft drive mechanism for a sewing machine described in claim 1, The lower end of the crank rod and the first gear are connected via a connecting member, the lower end of the crank rod and the connecting member are connected to each other in a structure in which either the lower end of the crank rod or the connecting member is pivotally supported by the other in a double-supported state, The connecting member and the first gear are connected in a structure in which either the connecting member or the first gear is supported by the other in a double-supported state.

[0010] The invention described in claim 5 is the hook shaft drive mechanism for a sewing machine described in any one of claims 1 to 3, The engine is characterized in that a case body is provided that houses at least the crank rod, the crank shaft, the first gear, and the second gear therein.

[0011] The invention described in claim 6 is the hook shaft drive mechanism for a sewing machine described in claim 5, The case body stores lubricating oil in an amount that immerses at least a portion of the first gear, a ventilation path for ventilating the inside and outside of the case body is provided on the top surface of the case body; The opening of the ventilation path facing the inside of the case body is located away from the upper shaft in a top view and faces the opposite side to the upper shaft.

[0012] The invention described in claim 7 is the hook shaft drive mechanism for a sewing machine described in claim 6, The opening of the ventilation path facing the inside of the case body is located on the opposite side of the upper shaft from the first gear when viewed from above, and is directed toward the opposite side of the upper shaft from the first gear. [Effects of the Invention]

[0013] According to the present invention, a hook shaft drive mechanism for a sewing machine that suppresses vibrations due to a double-supported connection structure can be obtained. Furthermore, noise caused by vibrations can also be suppressed. [Brief explanation of the drawings]

[0014] [Figure 1] 3 is an explanatory diagram showing the arrangement of a shuttle shaft drive mechanism of the sewing machine in the sewing machine frame of the embodiment. FIG. [Figure 2] FIG. 2 is a perspective view showing a shuttle shaft drive mechanism of the sewing machine according to the embodiment. [Figure 3] FIG. 10 is a perspective view of the shuttle shaft drive mechanism of the sewing machine of the present embodiment, seen from another angle. [Figure 4] FIG. 2 is an enlarged perspective view showing a crankshaft provided integrally with the upper shaft. [Figure 5]10 is an enlarged perspective view showing a portion where the lower end side of the crank rod and the first gear are connected via a connecting member. FIG. [Figure 6] FIG. 6 is an exploded perspective view of the connection portion shown in FIG. 5. [Figure 7] FIG. 2 is a top view showing the periphery of the crank rod with the inside of the case seen through. [Figure 8] 10 is an enlarged side view showing a ventilation member disposed on the underside of the lid of the case body. FIG. [Figure 9] FIG. 10 is an exploded perspective view showing a modified example of a connecting member that connects the lower end side of the crank rod and the first gear. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, embodiments of the present invention will be described in detail. The shuttle shaft drive mechanism of a sewing machine transmits the driving force of the upper shaft, which is rotated by a drive means, to the shuttle shaft via a crank rod or the like.

[0016] As shown in Figures 1 to 3, the shuttle shaft drive mechanism 1 of the sewing machine of this embodiment includes an upper shaft 10 rotated by a motor M serving as a drive means, a crank rod 20 connected at its upper end 20a to the upper shaft 10 via a crank shaft 12, a first gear 30 connected to the lower end 20b of the crank rod 20 so as to be able to swing, and a shuttle shaft 50 having a second gear 40 meshing with the first gear 30, and which is swingably rotated by the rotation of the upper shaft 10.

[0017] The shuttle shaft drive mechanism 1 of this sewing machine is disposed within the sewing machine frame. As shown in FIG. 1, the sewing machine frame has, for example, a sewing machine bed portion F1 that forms the lower part of the sewing machine, a standing body portion F2 that stands on the sewing machine bed portion F1, and a sewing machine arm portion F3 that is connected to the upper end of the standing body portion F2 and extends in a substantially horizontal direction so as to face the sewing machine bed portion F1. Generally, the upper shaft 10 is disposed in the machine arm portion F3, the crank rod 20 is disposed in the upright body portion F2, and the shuttle shaft 50 is disposed in the machine bed portion F1. One end of the upper shaft 10 is connected to a motor M, and the other end is connected to a needle bar up-down movement mechanism 15, with the upper shaft 10 being rotatably supported on the sewing machine arm portion F3 via a bearing or the like. The motor M is installed in a manner that it is exposed from the sewing machine arm portion F3. However, the motor M may also be built-in. In addition, a second gear 40 is arranged on one end of the shuttle shaft 50, and the other end is connected to the shuttle of the sewing machine (not shown). The shuttle shaft 50 is supported by the sewing machine bed portion F1 via a bearing or the like so as to be able to swing and rotate. The needle bar up-down movement mechanism 15 and the sewing machine shuttle (not shown) have the same configurations and operations as those of conventionally known devices, and will not be described in detail here. In this embodiment, the other end of the hook shaft 50 is connected to the inner hook of a so-called vertical semi-rotary hook, and a rocking rotation (reciprocating rotation) is imparted to the inner hook.

[0018] In this embodiment, the location where the upper end 20a of the crank rod 20 is connected to the upper shaft 10 is, for example, as shown in FIG. 4, a crankshaft 12 that is integral with the upper shaft 10 and has an eccentric axis relative to the upper shaft 10. That is, in the shuttle shaft drive mechanism 1 of the sewing machine of this embodiment, a crank mechanism is employed as the power transmission mechanism from the upper shaft 10 to the crank rod 20. The upper end 20a of the crank rod 20 has two semi-circular half-ring portions 21, 21 that are divided into two parts, and the upper end 20a of the crank rod 20 is connected to the crankshaft 12 in such a manner that the half-ring portions 21, 21 sandwich the crankshaft 12 and are fastened together with screws 22, 22. The crankshaft 12 and the upper end 20a of the crank rod 20 are rotatable relative to each other.

[0019] In addition, in the shuttle shaft drive mechanism 1 of the sewing machine of this embodiment, the lower end 20b side of the crank rod 20 and the first gear 30 are connected by a connecting structure in which either the lower end 20b side of the crank rod 20 or the first gear 30 is supported by the other in a double-supported state. In this embodiment, as shown in Figures 5 and 6, the connecting structure is exemplified by a configuration having a lower end 20b side of the crank rod 20, a connecting member 60 (described later) that connects the lower end 20b and the first gear 30, and a connecting shaft 61a as an axial member. In this connection structure, the lower end 20b of the crank rod 20 and the connecting member 60 are connected in a structure in which the lower end 20b of the crank rod 20 supports the connecting member 60 in a double-supported state, and the connecting member 60 and the first gear 30 are connected in a structure in which the connecting member 60 supports the first gear 30 in a double-supported state.

[0020] Here, we will explain in detail the connection structure, i.e., the connection point between the lower end 20b of the crank rod 20 and the first gear 30, where the lower end 20b of the crank rod 20 and the first gear 30 are connected via the connecting member 60.

[0021] 5 and 6, the connecting member 60 is a member having a first connecting end 61 on one end side and bifurcated second connecting end portions 62, 62 on the other end side. A connecting hole 61h is formed in the first connecting end 61, and a connecting hole 62h is formed individually and concentrically in the bifurcated portion of the second connecting end 62, and the connecting hole 61h and the connecting hole 62h, which are through holes, are formed in parallel to each other. The crank rod 20 has a bifurcated portion at its lower end 20b, and each bifurcated portion of the lower end 20b is individually and concentrically formed with a connecting hole 20h. The first gear 30 is a gear having an approximately fan shape, and a connecting hole 30h is formed at the point corresponding to the center of the fan, and a plurality of teeth that mesh with the second gear 40 are formed on the outer surface corresponding to the arc of the fan. The first gear 30 and the second gear 40 are helical gears with spiral tooth traces. The teeth of the first gear 30 and the second gear 40 are not limited to helical teeth, and may be parallel to the rotation axis.

[0022] The first connecting end 61 of the connecting member 60 is sandwiched between the forked portion on the lower end 20b side of the crank rod 20, and the connecting holes (20h, 61h) provided in the lower end 20b of the crank rod 20 and the first connecting end 61 are connected to each other, and a connecting shaft 61a is inserted into and attached to the connecting holes (20h, 61h), so that the lower end 20b of the crank rod 20 and the first connecting end 61 are axially attached. The connecting shaft 61a is fastened to the first connecting end 61 by a headless screw threaded into a screw hole formed in the first connecting end 61, and is rotatable relative to the lower end 20b of the crank rod 20. However, the connecting shaft 61a may also be fastened to the lower end 20b of the crank rod 20 by a headless screw and be rotatable relative to the first connecting end 61. In this way, the lower end 20b side of the crank rod 20 is connected to the connecting member 60 in a structure in which the connecting member 60 is supported at both ends.

[0023] In addition, the first gear 30 is sandwiched between the second connecting ends 62, 62 on the bifurcated side of the connecting member 60, and the connecting holes (62h, 30h) provided in the second connecting end 62 and the first gear 30 are connected to each other, and a connecting shaft 62a is inserted into and attached to the connecting holes (62h, 30h), thereby axially attaching the second connecting end 62 and the first gear 30. The connecting shaft 62a is fastened to the second connecting end 62 by a headless screw threaded into a screw hole formed in the second connecting end 62, and is also fastened to the first gear 30 by a headless screw threaded into a screw hole formed in the first gear 30. In this way, the connecting member 60 and the first gear 30 are connected via the connecting shaft 62a so as to be able to rotate back and forth integrally. In this way, the connecting member 60 is connected to the first gear 30 in a structure in which the first gear 30 is supported at both ends.

[0024] The connecting shaft 62a connecting the connecting member 60 and the first gear 30 is supported by the sewing machine bed portion F1 via a bearing, a metal bearing, or the like. When the upper shaft 10 is rotated by the drive of the motor M, the upper end 20a of the crank rod 20 rotates around the upper shaft 10, and a reciprocating motion in the vertical direction is transmitted to the lower end 20b of the crank rod 20. This motion is then transmitted to the first gear 30 via the connecting member 60, causing the first gear 30 to swing around the connecting shaft 62a as its axis. The swinging motion of the first gear 30 is then transmitted to the second gear 40, causing the shuttle shaft 50 to swing and rotate.

[0025] Further, a case body 70 is provided for accommodating at least the crank rod 20, the crank shaft 12, the first gear 30, and the second gear 40 in the shuttle shaft drive mechanism 1 of the sewing machine of this embodiment. As shown in Figures 1, 7 and 8, the case body 70 has a bottom surface portion that forms part of the sewing machine frame (sewing machine bed portion F1, upright body portion F2, sewing machine arm portion F3), four side surfaces, and a lid portion 71 that serves as a top surface portion, and has a roughly rectangular box shape. In FIG. 1, the front side of the sewing machine frame is cut away, and therefore the front side of the four side surfaces of the case body 70 is shown missing. Lubricating oil is stored inside the case body 70, and an oil gauge 72 for checking the amount of lubricating oil is provided on the bottom side of the case body 70. The oil level gauge 72 is, for example, a transparent resin tube. By visually checking the level of the lubricating oil in this tube, it is possible to check whether the amount of lubricating oil stored in the case body 70 is appropriate.

[0026] The case body 70 stores lubricating oil in an amount sufficient to immerse at least a portion of the first gear 30 therein. As mentioned above, the rotation of the upper shaft 10 is transmitted to the first gear 30 via the crank rod 20 and the connecting member 60, and the first gear 30 oscillates around the connecting shaft 62a as its axis. Since a portion of the first gear 30 is immersed in lubricating oil, the oscillating first gear 30 splashes the lubricating oil up inside the case body 70. Because this first gear 30 oscillates at a relatively high speed, the lubricating oil is splashed up to the upper part of the case body 70, and the splashed lubricating oil is supplied not only between the first gear 30 and the second gear 40, but also to the point where the lower end 20b of the crank rod 20 is connected to the first gear 30 via the connecting member 60, and the point where the upper end 20a of the crank rod 20 is connected to the crankshaft 12.

[0027] In order to prevent lubricating oil from leaking out from inside the case body 70, oil seals and the like are provided at the locations where the upper shaft 10 and the shuttle shaft 50 pass through the case body 70, and packings are provided at the joints of the sewing machine frame (sewing machine bed section F1, vertical body section F2, sewing machine arm section F3). However, if the inside of the case body 70 is made into a completely sealed space, when the sewing machine's shuttle shaft drive mechanism 1 is driven, the temperature rises due to frictional heat generated at the connecting points of each part of the drive mechanism, causing the internal pressure inside the case body 70 to increase, which can cause lubricating oil to seep out from gaps in the bearings, etc. For this reason, a ventilation member 80 having minute through holes formed therein is disposed in the case body 70, and the through holes of the ventilation member 80 serve as ventilation paths to prevent an increase in the internal pressure within the case body 70.

[0028] In this embodiment, a ventilation member 80 having a minute through-hole 81 formed therein and having a substantially L-shape is disposed on the underside of the lid portion 71 of the case body 70 . Specifically, as shown in Figures 7 and 8, a ventilation member 80 having a substantially L-shaped through hole 81 is disposed on the underside of the lid portion 71 of the case body 70 at a position sandwiching the upper shaft 10 between the lid portion 71 and the first gear 30 when viewed from above, with one opening 81a of the through hole 81 exposed facing upward and outward from the lid portion 71, and the other opening 81b of the through hole 81 facing away from the upper shaft 10 when viewed from above. 7 and 8, a ventilation member 80 having a substantially L-shaped through hole 81 is disposed on the underside of the lid portion 71 of the case body 70, at a position between the upper shaft 10 and an inner surface 70a on the front side of the case body 70, which is disposed so that the upper shaft 10 is sandwiched between the lid portion 71 and the first gear 30 in top view, and one opening 81a of the through hole 81 is exposed to the outside from the lid portion 71. The other opening 81b of the through hole 81 is located at a position spaced apart to one side of the upper shaft 10 (the lower side of the paper in FIG. 7, the right side of the paper in FIG. 8) in top view, and the other opening 81b faces the opposite side to the upper shaft 10 (the lower side of the paper in FIG. 7, the right side of the paper in FIG. 8). In other words, when viewed from above, the ventilation member 80 is disposed on the underside of the lid portion 71 of the case body 70 with the other opening 81b of the ventilation member 80 facing the inner surface 70a on the front side of the case body 70, with its back facing the upper shaft 10 and the first gear 30.

[0029] The ventilation member 80 is disposed in such a position, and the other opening 81b of the ventilation member 80 faces away from the first gear 30 and faces the inner surface 70a on the front side of the case body 70. Therefore, even if the oscillating first gear 30 splashes the lubricating oil upward inside the case body 70, the lubricating oil is less likely to get on the other opening 81b side of the ventilation member 80. Therefore, it is difficult for the lubricating oil to enter the through-holes 81 of the ventilation member 80, and the lubricating oil is hardly leaked out through the through-holes 81. Furthermore, by providing this ventilation member 80 in the case body 70, the internal pressure within the case body 70 does not increase, so that seepage of lubricating oil from gaps in bearings and the like is suppressed.

[0030] As described above, in the shuttle shaft drive mechanism 1 of the sewing machine of this embodiment, the lower end 20b side of the crank rod 20 and the first gear 30 are connected via the connecting member 60, and the lower end 20b side of the crank rod 20 and the connecting member 60 are connected in a structure in which the lower end 20b side of the crank rod 20 supports the connecting member 60 in a double-supported state, and the connecting member 60 and the first gear 30 are connected in a structure in which the connecting member 60 supports the first gear 30 in a double-supported state. If the connection point where power is transmitted from the crank rod 20 to the first gear 30 is supported at both ends in this manner, the uneven load at the connection point is reduced, resulting in a well-balanced connection structure with balanced forces, which reduces vibrations that occur at the connection point and reduces noise generation. On the other hand, when the connection between the lower end of the crank rod and the pendulum gear is supported in a cantilevered manner, as in the above-mentioned prior art (JP Patent Publication No. 2003-236282), an unbalanced load is likely to occur at the connection, which is likely to cause vibration and noise, which can be a problem.

[0031] Furthermore, in the shuttle shaft drive mechanism 1 of the sewing machine of this embodiment, a crank mechanism using the crankshaft 12 is employed as the power transmission mechanism from the upper shaft 10 to the crank rod 20, so vibrations can be further suppressed and noise caused by vibrations can be reduced compared to power transmission using an eccentric cam mechanism as in the prior art. In the case of an eccentric cam mechanism like that of the prior art, the eccentric cam is a relatively large component, and the upper end of the crank rod, which is enlarged to hold the eccentric cam, is excessively heavy, making it prone to vibration when rotating, and this vibration is likely to generate noise. In contrast, in the case of a crank mechanism in which the upper end 20a of the crank rod 20 is connected to the crankshaft 12, as in the shuttle shaft drive mechanism 1 of the sewing machine of this embodiment, the rotating parts such as the crankshaft 12 and the upper end 20a of the crank rod 20, which contribute to power transmission, can be made lighter than in an eccentric cam mechanism, so that vibrations caused by rotation can be suppressed and noise generation can be reduced.

[0032] Furthermore, in the shuttle shaft drive mechanism 1 of the sewing machine of this embodiment, at least the crank rod 20, crank shaft 12, first gear 30, and second gear 40 are housed inside the case body 70, so that noise generated at the connection points of each part of the drive mechanism can be reduced. Specifically, by accommodating within the case body 70 locations that are likely to be sources of noise, such as the connection point between the upper end 20a of the crank rod 20 and the crankshaft 12, the connection point between the lower end 20b of the crank rod 20 and the first gear 30 via the connecting member 60, and the location where the first gear 30 and the second gear 40 mesh, noise generated within the case body 70 can be insulated, thereby reducing the noise at each of these locations.

[0033] Furthermore, the lubricating oil stored in the case body 70 is splashed up to the upper part of the case body 70 by the oscillating first gear 30, and the splashed lubricating oil is supplied to the space between the first gear 30 and the second gear 40, the portion where the lower end 20b of the crank rod 20 is connected to the first gear 30 via the connecting member 60, and the portion where the upper end 20a of the crank rod 20 is connected to the crankshaft 12, thereby lubricating each of these parts and reducing friction and wear. Furthermore, by supplying lubricating oil to each of these parts, heat generated by friction can be removed. By supplying lubricating oil in this manner, vibration and noise from each part of the shuttle shaft drive mechanism 1 of the sewing machine can be reduced.

[0034] Furthermore, since the first gear 30 and the second gear 40 are helical gears, the driving noise can be reduced.

[0035] As described above, with the shuttle shaft drive mechanism 1 for the sewing machine of this embodiment, it is possible to suppress the vibrations generated in each part of the drive mechanism and the noise caused by the vibrations.

[0036] The present invention is not limited to the above embodiment. For example, as shown in FIG. 9, the lower end 20b side of the crank rod 20 and the first gear 30 may be connected via a pair of connecting members 63. The pair of connecting members 63 has connecting holes 61h, 61h formed at one end thereof, which is bifurcated, and connecting holes 62h, 62h formed at the other end thereof, which is bifurcated. The connecting holes 61h and 62h, which are through holes, are formed parallel to each other. The pair of connecting members 63 may be integrally connected via a connecting part (not shown), or the pair of connecting members 63 may be composed of two separate members. The crank rod 20 has a single rod-like lower end 20b, which is formed with a connecting hole 20h.

[0037] The lower end 20b of the crank rod 20 is sandwiched between the forked portions on one end side of the pair of connecting members 63, and the lower end 20b of the crank rod 20 is connected to the connecting holes (20h, 61h) provided in each of the pair of connecting members 63, and a connecting shaft 61a is inserted into and attached to the connecting holes (20h, 61h), so that the lower end 20b of the crank rod 20 and one end side of the pair of connecting members 63 are axially attached. The connecting shaft 61a is fastened to the pair of connecting members 63 by headless screws threaded into screw holes formed in each of the pair of connecting members 63, and is rotatable relative to the lower end 20b of the crank rod 20. However, the connecting shaft 61a may also be fastened to the lower end 20b of the crank rod 20 by headless screws and be rotatable relative to the pair of connecting members 63. In this way, one end side of the pair of connecting members 63 is connected to the lower end 20b side of the crank rod 20 in a double-supported state.

[0038] In addition, the first gear 30 is sandwiched between the forked portions on the other end sides of the pair of connecting members 63, and the connecting holes (62h, 30h) provided on the pair of connecting members 63 and the first gear 30 are connected to each other, and a connecting shaft 62a is inserted into and attached to the connecting holes (62h, 30h), so that the other end sides of the pair of connecting members 63 and the first gear 30 are axially attached. The connecting shaft 62a is fastened to the pair of connecting members 63 by headless screws threaded into screw holes formed in the pair of connecting members 63, and is also fastened to the first gear 30 by headless screws threaded into screw holes formed in the first gear 30. In this way, the pair of connecting members 63 and the first gear 30 are connected via the connecting shaft 62a so as to be able to rotate back and forth integrally. In this way, the other ends of the pair of connecting members 63 are connected in a structure in which the first gear 30 is supported at both ends.

[0039] Even when such a pair of connecting members 63 is used, and one end of the pair of connecting members 63 supports the lower end 20b of the crank rod in a double-supported state, and the other end of the pair of connecting members 63 supports the first gear 30 in a double-supported state, uneven loads at the connection points are suppressed, resulting in a well-balanced connection structure with balanced forces, and therefore vibrations occurring at the connection points can be suppressed, and noise generation can be reduced.

[0040] In the above embodiment, examples have been described in which the lower end 20b of the crank rod 20 is connected to the first gear 30 using a connecting member 60 having a first connecting end 61 on one end and bifurcated second connecting ends 62, 62 on the other end, and in which the lower end 20b of the crank rod 20 is connected to the first gear 30 using a pair of connecting members 63, but the present invention is not limited to these. For example, the portion of the first gear 30 where the connecting hole 30h is provided may be formed in a bifurcated manner, and the other end of the connecting member may be supported at both ends by the bifurcated portion of the first gear 30.

[0041] The first gear 30 may also have a connecting portion that extends radially from the connecting hole 30h toward the opposite side from the portion where the helical teeth are formed. In this case, by providing a through-hole in the connecting portion that functions in the same way as the connecting hole 61h of the first connecting end 61 of the connecting member 60, it becomes possible to connect the first gear 30 to the lower end 20b of the crank rod 20 via the connecting shaft 61a, making the connecting member 60 unnecessary. Furthermore, the first gear 30 and the pair of connecting members 63 shown in FIG. 9 may be integrated into one member without using the connecting shaft 62a.

[0042] Furthermore, it goes without saying that other specific detailed structures and the like can be modified as appropriate. [Explanation of symbols]

[0043] 1. Sewing machine hook shaft drive mechanism 10 Upper shaft 12 crankshaft 20 crank rod 20a top end 20b Lower end (connection structure, bifurcated part) 30 First Gear 40 2nd gear 50 pot shaft 60 Connecting member (connecting structure) 61 1st connection end 61a Connection shaft (connection structure, shaft member) 62 2nd connection end 62a Connecting shaft 63 Pair of connecting members (connecting structure, bifurcated portion) 70 Case body 71 Lid section (top section) 80 Ventilation material 81 Through hole (ventilation path) 81a One opening 81b Other opening M motor (drive means) F1 Sewing machine bed F2 Standing trunk F3 Sewing machine arm

Claims

1. a crank rod whose upper end is connected to a crankshaft provided eccentrically on an upper shaft rotated by a driving means; a first gear that rotates reciprocally in response to the reciprocating movement of the lower end of the crank rod; a second gear meshing with the first gear; a hook shaft that is oscillated and rotated by the second gear; A hook shaft drive mechanism for a sewing machine, comprising: The lower end of the crank rod and the first gear are connected by a connecting structure in which either the lower end of the crank rod or the first gear is supported by the other in a double-supported state.

2. The connecting structure is a bifurcated portion formed on the lower end side of the crank rod; 2. The hook shaft drive mechanism of claim 1, further comprising a shaft member supported at both ends by said forked portion.

3. The connecting structure is a bifurcated portion that rotates back and forth integrally with the first gear; 2. The hook shaft drive mechanism of claim 1, further comprising a shaft member supported at both ends by said forked portion.

4. The lower end of the crank rod and the first gear are connected via a connecting member, the lower end of the crank rod and the connecting member are connected to each other in a structure in which either the lower end of the crank rod or the connecting member is pivotally supported by the other in a double-supported state, 2. The rotary hook shaft drive mechanism of a sewing machine according to claim 1, wherein the connecting member and the first gear are connected by a structure in which either the connecting member or the first gear is supported by the other in a double-supported state.

5. 4. The hook shaft drive mechanism for a sewing machine according to claim 1, further comprising a case body for accommodating at least the crank rod, the crank shaft, the first gear, and the second gear therein.

6. The case body stores lubricating oil in an amount that immerses at least a portion of the first gear, a ventilation path for ventilating the inside and outside of the case body is provided on the top surface of the case body; 6. The shuttle shaft drive mechanism for a sewing machine according to claim 5, wherein an opening of the ventilation path facing the inside of the case body is positioned away from the upper shaft in a top view and faces away from the upper shaft.

7. 7. The shuttle shaft drive mechanism for a sewing machine according to claim 6, wherein an opening of the ventilation path facing the inside of the case body is located on the opposite side of the upper shaft from the first gear when viewed from above, and is directed toward the opposite side of the upper shaft from the first gear.

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