Needle-threading device for sewing machine and sewing machine equipped with said device

Abstract

The needle-threading device includes a needle-threading shaft that is parallel to a vertically-moving needle bar and that is vertically movable and rotatable, a control lever that lowers and rotates the needle-threading shaft, a needle-threading end section provided at a lower end of the needle-threading shaft and having a needle-threading hook, and a needle-threading stopper provided at the needle bar and defining a lowered stoppage position of the needle-threading shaft. The needle-threading end section lowered by operating the control lever rotates at the lowered stoppage position and causes the needle-threading hook to be inserted through a needle hole of one needle of a plurality of needles provided at the needle bar. The needle-threading end section includes a sliding body that vertically moves relative to the needle-threading shaft, a positioning body slidable relative to the sliding body, and an interlocking mechanism that vertically moves the sliding body.

Claims

1. A needle-threading device for a sewing machine, the needle-threading device comprising: a needle-threading shaft that is parallel to a vertically-moving needle bar and that is vertically movable and rotatable; a control lever that lowers and rotates the needle-threading shaft; a needle-threading end section provided at a lower end of the needle-threading shaft and having a needle-threading hook; and a needle-threading stopper provided at the needle bar and defining a lowered stoppage position of the needle-threading shaft, wherein the needle-threading end section lowered by operating the control lever rotates at the lowered stoppage position and causes the needle-threading hook to be inserted through a needle hole of one needle of a plurality of needles provided at the needle bar, wherein the needle-threading end section includes a sliding body that vertically moves relative to the needle-threading shaft, a positioning body slidable relative to the sliding body, and an interlocking mechanism that vertically moves the sliding body relative to the needle-threading shaft in accordance with sliding of the positioning body, and wherein the interlocking mechanism includes a reference pin provided at the needle-threading shaft and a slot cam that is provided in the positioning body and with which the reference pin is in slidably contact, the slot cam having at least three stepped cam surfaces corresponding to at least three different heights of needle holes respectively in the plurality of needles.

2. The needle-threading device for the sewing machine according to claim 1, wherein the sliding body includes a switch lever that defines a slide position of the positioning body and a switch spring that retains the slide position of the positioning body by the switch lever, and wherein the positioning body includes a switch cam having a notch that engages with the switch spring.

3. The needle-threading device for the sewing machine according to claim 2, wherein the sliding body includes an eccentric pin that adjusts a sliding distance of the positioning body.

4. The sewing machine comprising the needle-threading device according to claim 1, wherein the sliding body includes an eccentric pin that adjusts a sliding distance of the positioning body.

5. The needle-threading device for the sewing machine according to claim 1, wherein each of the stepped cam surfaces are at different distances from each other vertically and horizontally.

6. The needle-threading device for the sewing machine according to claim 5, wherein the sliding body includes a switch lever that defines a slide position of the positioning body and a switch spring that retains the slide position of the positioning body by the switch lever, and wherein the positioning body includes a switch cam having notches that engage with the switch spring, each of the notches respectively corresponding to each of the stepped cam surfaces.

7. The needle-threading device for the sewing machine according to claim 6, wherein each of the notches are at different pitches from each other.

8. A sewing machine comprising the needle-threading device according to claim 1.

9. A sewing machine comprising the needle-threading device according to claim 2.

10. A sewing machine comprising the needle-threading device according to claim 4.

11. A sewing machine comprising the needle-threading device according to claim 3.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a schematic diagram of a sewing machine equipped with a needle-threading device according to an embodiment of the present invention.

(2) FIG. 2 is an enlarged view illustrating a relevant part of needles in FIG. 1.

(3) FIG. 3 is a schematic diagram illustrating the structure of a needle driving device and the needle-threading device according to the embodiment of the present invention.

(4) FIG. 4 is a diagram illustrating the internal structure of a needle-threading end section of the needle-threading device according to the embodiment of the present invention.

(5) FIG. 5 includes diagrams illustrating the positioning of a needle-threading hook relative to a needle-threading shaft (reference pin) of the needle-threading device according to the embodiment of the present invention, and includes a diagram (a) illustrating a positioned state in a needle hole 2L, a diagram (b) illustrating a positioned state in a needle hole 2M, and a diagram (c) illustrating a positioned state in a needle hole 2R.

(6) FIG. 6 includes schematic diagrams illustrating the operation of the needle-threading device according to the embodiment of the present invention, and includes a front view (a) illustrating a standby mode and a front view (b) illustrating a needle-threading mode.

DESCRIPTION OF EMBODIMENTS

(7) A needle-threading device for a sewing machine according to an embodiment of the present invention will now be described with reference to the drawings indicated in the embodiment.

(8) Referring to FIG. 1, in the following description, the vertical direction will be defined as up-down, the horizontal direction will be defined as left-right, and the direction orthogonal to the plane of the drawing will be defined as front-rear.

Embodiment

(9) In FIG. 1, A denotes a needle driving device provided at a head portion of a sewing machine N and for vertically moving a needle bar 4 that secures three needles 1 by using a needle clamp 3, and B denotes a needle-threading device for threading a thread T (TL, TM, TR) supplied from a thread spool K (KL, KM, KR) through a needle hole 2 (2L, 2M, 2R, see FIG. 2) in the needle 1 (1L, 1M, 1R) of the needle driving device A.

(10) The needle-threading device B includes a needle-threading shaft 10 that is parallel to the needle bar 4, a control lever 20 that is exposed from the head portion of the sewing machine N and that lowers the needle-threading shaft 10, and a needle-threading end section 30 provided at the lower end of the needle-threading shaft 10.

(11) As shown in FIG. 2, in this embodiment, the needles 1 of the needle driving device A include three needles 1L, 1M, and 1R provided from left to right at pitches (distances) D (LM) and D (MR) that are equal to each other. With regard to the needle holes 2L, 2M, and 2R of the three needles 1, a height h1 between 2L and 2M and a height h2 between 2M and 2R are different from each other.

(12) Accordingly, since the heights of the needle holes 2 are set such that stitches can be reliably formed in accordance with the mechanism of the sewing machine N and the threads T moving in conjunction with the movement of the needles 1, the height h1 and the height h2 are not equal to each other.

(13) Therefore, although the needle holes 2L, 2M, and 2R can be connected by the circular arc E from the center O, since the height of the needle hole 2M has a vertical positional difference with a line S connecting the needle hole 2L and the needle hole 2R to each other, the needle holes 2L, 2M, and 2R cannot be connected by the line S having an angle of from a horizontal line.

(14) Although this embodiment is described with reference to an example where the needles 1 are the three needles 1L, 1M, and 1R with the needle holes 2 at different heights, the needles 1 may be four or more needles at different heights.

(15) As shown in FIG. 3, the needle driving device A includes the needle bar 4 to which the three needles 1 of 1L, 1M, and 1R are secured by using the needle clamp 3, a needle-bar connecting bracket 5 that is connected to the needle bar 4 and that is vertically driven by a needle vertically-driving mechanism (not shown), and a needle-threading stopper 6 that is secured to the needle bar 4 and that defines a lowered stoppage position of the needle-threading shaft 10 provided in the needle-threading device B to be described below. The needle-threading stopper 6 has a stopper slot 7 recessed from above.

(16) As shown in FIG. 3, the needle-threading device B includes the needle-threading shaft 10 that is parallel to the needle bar 4 and that is supported in a vertically-movable and rotatable manner by a needle-threading-shaft support plate 15, the control lever 20 that is supported in a vertically-movable manner along the needle-threading-shaft support plate 15 and that lowers and rotates the needle-threading shaft 10, and the needle-threading end section 30 provided at the lower end of the needle-threading shaft 10 and having a needle-threading hook 31.

(17) A midpoint of the needle-threading shaft 10 is provided with a stopper pin 11 that can be brought into abutment with the lower end of the stopper slot 7 of the needle-threading stopper 6.

(18) The needle-threading-shaft support plate 15 is secured to a frame of the sewing machine N, is provided with a needle-threading-shaft slot 17 extending in the up-down direction of a rear surface plate 16, is provided with an upper bearing 18 at the upper end, and is provided with a lower bearing 19 at the lower end.

(19) The needle-threading shaft 10 is fitted in the upper bearing 18 and the lower bearing 19 of the needle-threading-shaft support plate 15. The rear side of the stopper pin 11 is fitted in the needle-threading-shaft slot 17 of the needle-threading-shaft support plate 15. A needle-threading return spring 12 is disposed between the stopper pin 11 of the needle-threading shaft 10 and the lower bearing 19 and biases the stopper pin 11 upward to bring the stopper pin 11 into abutment with the upper end of the needle-threading-shaft slot 17.

(20) The control lever 20 includes a support-plate slide hole 21 in which the rear surface plate 16 of the needle-threading-shaft support plate 15 is fitted in the up-down direction and that is split into front and rear portions, although not shown, a shaft hole 22 in which the needle-threading shaft 10 is fitted in the up-down direction, a needle-threading-shaft rotating cam 23 that is provided to extend across the support-plate slide hole 21 and that engages with the stopper pin 11, and a knob 24 exposed from the head portion of the sewing machine N, as shown in FIG. 1.

(21) As shown in FIGS. 3 and 4, the needle-threading end section 30 includes a sliding body 40 that moves vertically relative to the needle-threading shaft 10 and that is split into front and rear portions, although not shown, and a positioning body 50 slidable relative to the sliding body 40 in the direction in which the needles 1 are arranged. The positioning body 50 is provided with the needle-threading hook 31 with a hook arm 55 interposed therebetween.

(22) The sliding body 40 includes a reference-pin slide long hole 45 and slides relative to a reference pin 13 secured to a lower portion of the needle-threading shaft 10. For biasing the sliding body 40 downward, the needle-threading shaft 10 is provided with a pressure spring 33 between an E-shaped snap ring 32, which is secured to the needle-threading shaft 10, and the sliding body 40.

(23) The sliding body 40 includes a switch lever 41 that defines a slide position of the positioning body 50. The switch lever 41 has an action pin 43 that pivots about a fulcrum pin 42 pivotally attached to the sliding body 40. When the switch lever 41 is operated in the direction of an arrow in response to the action pin 43 engaging with an action-pin slide long hole 51 provided in the positioning body 50, the positioning body 50 slides relative to the sliding body 40 in the direction of the line S having the angle of from the horizontal line.

(24) As shown in FIGS. 1 and 3, L, M, and R corresponding to the three needles 1L, 1M, and 1R are indicated as switch positions of the switch lever 41 on the surface of the sliding body 40 (needle-threading end section 30).

(25) The positioning body 50 includes a switch cam 52 having three notches (recesses) 53 at the same distances as the pitches D (LM) and D (MR) of the three needles 1 in the sliding direction. The notches 53 in the switch cam 52 engage with a switch spring 44 provided at the sliding body 40 so that the positioning body 50 is retained at the slide positions corresponding to the three needles 1L, 1M, and 1R by the switch lever 41.

(26) Furthermore, the positioning body 50 includes the reference pin 13 secured to the needle-threading shaft 10 and a slot cam 54 with which the reference pin 13 is in slidably contact. The reference pin 13 and the slot cam 54 serve as an interlocking mechanism that vertically moves the sliding body 40 relative to the needle-threading shaft 10 in accordance with the slide positions corresponding to the three needles 1L, 1M, and 1R by the switch lever 41.

(27) The slot cam 54 has a stepped shape having an L surface 54a, an M surface 54b, and an R surface 54c as three stepped cam surfaces corresponding to the heights of the needle holes 2L, 2M, and 2R.

(28) The pressure spring 33 biasing the sliding body 40 is provided for preventing looseness between the reference pin 13 and the slot cam 54, and is omittable.

(29) In this embodiment, distances Da (LM) and Da (MR) between the notches 53 in the switch cam 52 are set to be greater than the pitches D (LM) and D (MR) of the actual needles 1. By rotating an L adjustment pin 46 and an R adjustment pin 47 serving as eccentric pins, D (LM) and D (MR) serving as the sliding distances of the positioning body 50 can be adjusted, thereby coping with variations in the pitches of the needles 1.

(30) Next, the usage and the advantageous effects of this embodiment will be described.

(31) In order to thread the threads TL, TM, and TR through the needle holes 2L, 2M, and 2R in the three needles 1 by using the needle-threading device B according to this embodiment, the switch lever 41 is first manually set to the position L indicated on the surface of the sliding body 40 in a standby mode shown in FIG. 1 and FIG. 6(a).

(32) Then, as shown in FIG. 5(a), the left end of the positioning body 50 comes into abutment with the L adjustment pin 46, the right notch 53 of the switch cam 52 engages with the switch spring 44 provided at the sliding body 40, and the reference pin 13 comes into slidably contact with the L surface 54a of the slot cam 54, whereby the slide position of the positioning body 50 is defined such that the needle-threading hook 31 corresponds to the position (L position) of the needle hole 2L in the needle 1L.

(33) Then, when the knob 24 of the control lever 20 exposed from the head portion of the sewing machine N is pressed down from the state shown in FIG. 6(a), the needle-threading shaft 10 descends and causes the stopper pin 11 shown in FIG. 3 to come into contact with the lower end of the stopper slot 7 of the needle-threading stopper 6, whereby the vertical positions of the needle driving device A and the needle-threading device B are defined.

(34) Furthermore, the stopper pin 11 is also fitted in the needle-threading-shaft slot 17 and the needle-threading-shaft rotating cam 23. When the knob 24 of the control lever 20 is further pressed down after the stopper pin 11 comes into contact with the lower end of the stopper slot 7, the needle-threading shaft 10 is rotated in the direction of the arrow shown in FIG. 3 by the stopper pin 11 engaged with the needle-threading-shaft rotating cam 23, and the needle-threading hook 31 is inserted through the needle hole 2L in the needle 1L, as shown in FIG. 6(b).

(35) In this case, the stopper pin 11 is retained at the lower end of the stopper slot 7 of the needle-threading stopper 6, and the needle-threading hook 31 is maintained in the inserted state in the needle hole 2L.

(36) Subsequently, the thread TL is manually hooked to the needle-threading hook 31 in the inserted state, and the knob 24 of the control lever 20 is lifted and restored, so that after the needle-threading hook 31 still holding the thread TL ascends while receding from the needle hole 2L, the thread TL is removed from the needle-threading hook 31, whereby the needle-threading can be completed.

(37) The mechanism that involves lowering the needle-threading shaft 10 by operating the control lever 20, subsequently inserting the needle-threading hook 31 through the needle hole 2 of the needle 1 by rotating the needle-threading shaft 10, and maintaining this state is disclosed in detail in Japanese Unexamined Patent Application Publication No. 2011-240051.

(38) Subsequently, when the switch lever 41 is manually operated rightward so as to be set at the indicated position M, the left end of the positioning body 50 moves away from the L adjustment pin 46 and slides rightward along the line S, as shown in FIG. 5(b). The middle notch 53 of the switch cam 52 engages with the switch spring 44 provided at the sliding body 40, and the reference pin 13 comes into slidably contact with the M surface 54b of the slot cam 54, whereby the slide position of the positioning body 50 is defined such that the needle-threading hook 31 corresponds to the position (M position) of the needle hole 2M in the needle 1M.

(39) In this case, when the slide position of the positioning body 50 is switched from the L position to the M position by the switch lever 41, the cam surface shape of the slot cam 54 in slidably contact with the reference pin 13 switches from the L surface to the M surface, and the position of the needle-threading end section 30 relative to the needle-threading shaft 10 changes by a predetermined difference according to the cam surface shape.

(40) Specifically, with regard to the needle-threading end section 30, the vertical position of the reference pin 13 relative to the sliding body 40 changes in accordance with the cam surface shape of the slot cam 54 in conjunction with the sliding of the positioning body 50 relative to the sliding body 40, and this change causes the vertical positional difference to occur between the needle-threading end section 30 and the needle-threading shaft 10.

(41) Subsequently, similar to the threading through the needle hole 2L in the needle 1L, the knob 24 of the control lever 20 is operated, so that the threading of the thread TM through the needle hole 2M in the needle 1M can be completed.

(42) Finally, when the switch lever 41 is manually operated further rightward so as to be set at the indicated position R, the positioning body 50 slides rightward along the line S so that the right end comes into abutment with the R adjustment pin 47, as shown in FIG. 5(c). The left notch 53 of the switch cam 52 engages with the switch spring 44 provided at the sliding body 40, and the reference pin 13 comes into slidably contact with the R surface 54c of the slot cam 54, whereby the slide position of the positioning body 50 is defined such that the needle-threading hook 31 corresponds to the position (R position) of the needle hole 2R in the needle 1R.

(43) In this case, when the slide position of the positioning body 50 is switched from the M position to the R position by the switch lever 41, the cam surface shape of the slot cam 54 in slidably contact with the reference pin 13 switches from the M surface to the R surface, and the position of the needle-threading end section 30 relative to the needle-threading shaft 10 returns to the same position as the L position.

(44) Subsequently, by pressing down the knob 24 of the control lever 20 similarly as before, the threading of the thread TR through the needle hole 2R in the needle 1R can be completed.

(45) Accordingly, the movement of the positioning body 50 along the line S relative to the sliding body 40 and the displacement according to the cam surface shape of the slot cam 54 are combined with each other, so that the needle-threading hook 31 can be moved along an arbitrary trajectory extending through the needle holes 2L, 2M, and 2R.

(46) In other words, even if multiple vertical positions between the needle driving device A and the needle-threading device B are not defined by the stopper pin 11, similar advantages can be achieved with a simple structure, and the convenience and reliability of the needle-threading process as well as the size reduction of the needle-threading device B in the sewing machine N can be simultaneously achieved.

(47) As described above, with regard to the needle-threading device B according to this embodiment, the needle-threading end section 30 is lowered by manually operating the control lever 20, the needle-threading hook 31 is inserted through the needle hole 2 in each needle 1, the thread T is subsequently hooked to the manually-inserted needle-threading hook 31, and the control lever 20 is lifted and restored, so that after the needle-threading hook 31 recedes from the needle hole 2 while still holding the thread T, the thread T is removed from the needle-threading hook 31, whereby the needle-threading can be completed.

(48) Then, the switch lever 41 is manually operated, so that the positioning body 50 provided with the needle-threading hook 31 moves relative to the sliding body 40 by arbitrary amounts in the left-right direction and the up-down direction, thereby allowing for threading through the needle hole 2 in each needle 1 even in the sewing machine N having attached thereto the three needles 1 at different height positions.

(49) Although the control lever 20 and the switch lever 41 are manually operated in the needle-threading device B according to this embodiment, the levers may be electrically driven by providing, for example, an additional motor or a solenoid.

(50) Although the slide angle of the positioning body 50 in the needle-threading device B according to this embodiment is an angle between the line S connecting the needle hole 2L and the needle hole 2R to each other and the horizontal line, for example, the slide angle may be an angle formed with a line not extending through the needle hole 2R.

INDUSTRIAL APPLICABILITY

(51) In the needle-threading device, the switch lever is manually operated, so that the needle-threading hook provided at the needle-threading end section of the needle-threading device moves relative to the needle-threading shaft by arbitrary amounts in the left-right direction and the up-down direction. Thus, the present invention is advantageous particularly as a needle-threading device used in a sewing machine equipped with multiple needles at different height positions.

REFERENCE SIGNS LIST

(52) A needle driving device B needle-threading device D pitch (distance) E circular arc K, KL, KM, KR thread spool N sewing machine O center S line T, TL, TM, TR thread h1, h2 height difference angle 1, 1L, 1M, 1R needle 2, 2L, 2M, 2R needle hole 3 needle clamp 4 needle bar 5 needle-bar connecting bracket 6 needle-threading stopper 7 stopper slot 10 needle-threading shaft 11 stopper pin 12 needle-threading return spring 13 reference pin (interlocking mechanism) 15 needle-threading-shaft support plate 16 rear surface plate 17 needle-threading-shaft slot 18 upper bearing 19 lower bearing 20 control lever 21 support-plate slide hole 22 shaft hole 23 needle-threading-shaft rotating cam 24 knob 30 needle-threading end section 31 needle-threading hook 32 E-shaped snap ring 33 pressure spring 40 sliding body 41 switch lever 42 fulcrum pin 43 action pin 44 switch spring 45 reference-pin slide long hole 46 L adjustment pin (eccentric pin) 47 R adjustment pin (eccentric pin) 50 positioning body 51 action-pin slide long hole 52 switch cam 53 notch 54 slot cam (interlocking mechanism) 54a L surface 54b M surface 54c R surface 55 hook arm