Sewing machine

Abstract

To provide a sewing machine capable of adjusting timing, according to a sewn object, to change energizing force added to a presser foot mounted on a lower end of a presser bar by interlocking with a sewing machine motor by a simpler operation than before.SOLUTION: A sewing machine comprises: a needle plate; a feed dog; a presser bar 8; a presser bar guide bracket 82; an adjustment part 65; a presser spring 81; a regulation part 67; and a changing member 70. The changing member 70 has a first member 71 and a second member 72 and changes a position in a vertical direction of the regulation part 67 depending on distance between the first member 71 and the second member 72. Energizing force of the presser spring 81 is transmitted to the presser bar 8 when the presser bar 8 is in a first state where an upper end of the feed dog is located above an upper end of the needle plate, and the adjustment part 65 is separated from the regulation part 67. The energizing force of the presser spring 81 is not transmitted to the presser bar 8 in a second state where the upper end of the feed dog is located below the upper end of the needle plate, and the adjustment part 65 abuts against the regulation part 67.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a sewing machine.

Background Art

[0002] A conventional presser device for a sewing machine includes a connecting member, a moving member, and an elastic member (see, for example, Patent Document 1). The connecting member is connected to the main shaft of the sewing machine and swings. The moving member moves in the vertical direction as the connecting member swings. The elastic member is disposed between the moving member and the presser bar, and changes the elastic force applied to the presser bar by the movement of the moving member. The presser device moves the moving member so that the biasing force of the elastic member becomes larger when the feed teeth are raised above the needle plate than when the feed teeth are located below the needle plate, thereby changing the biasing force applied to the presser foot provided at the lower end of the presser bar in conjunction with the main shaft of the sewing machine. The sewing machine allows the user to adjust the initial settings in order to absorb changes according to the thickness and hardness of the workpiece.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a conventional presser device for a sewing machine, the configuration for changing the pressing force applied by the presser foot to the workpiece is complicated, and the timing for changing the biasing force applied to the presser foot attached to the lower end of the presser bar in conjunction with the sewing machine motor is adjusted according to the workpiece, which requires a complicated adjustment operation.

[0005] An object of the present invention is to provide a sewing machine that can adjust the timing for changing the biasing force applied to the presser foot attached to the lower end of the presser bar in conjunction with the sewing machine motor according to the workpiece by a simpler operation than in the prior art.

Means for Solving the Problems

[0006] A sewing machine according to one aspect of the present invention includes a sewing machine motor, a needle bar having a sewing needle attachable to its lower end and moving vertically in response to the drive of the sewing machine motor, a needle plate having a needle hole through which the sewing needle is inserted, feed teeth that protrude from and retract into an opening formed in the needle plate in response to the drive of the sewing machine motor and feed a workpiece placed on the needle plate, a presser bar having a presser foot attachable to its lower end and moving in the vertical direction in synchronization with the drive of the feed teeth, a presser bar holder fixed to the presser bar, an adjustment portion movable in the vertical direction, a presser spring that can bias the presser bar downward via the adjustment portion and the presser bar holder, a restricting portion that restricts the transmission of the biasing force of the presser spring to the presser bar when in contact with the adjustment portion, a first member, and a second member movably supported with respect to the first member, and includes a changing member that changes the vertical position of the restricting portion according to the distance between the first member and the second member. The upper end of the teeth of the feed teeth is above the upper end of the plate of the needle plate, and in a first situation where the adjustment portion is separated from the restricting portion, the adjustment portion and the presser bar holder come into contact, and the biasing force of the presser spring is transmitted to the presser bar. The upper end of the teeth is below the upper end of the plate, and in a second situation where the adjustment portion comes into contact with the restricting portion, the adjustment portion and the presser bar holder are separated in the vertical direction, and the biasing force of the presser spring is not transmitted to the presser bar. The sewing machine of this aspect allows the user to adjust the timing at which the biasing force of the presser spring is transmitted or not transmitted to the presser bar by a relatively simple operation of changing the distance between the first member and the second member. Therefore, the sewing machine contributes to making it easier than before to adjust the timing of changing the biasing force applied to the presser foot attached to the lower end of the presser bar in accordance with the workpiece, in conjunction with the sewing machine motor.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Embodiments for Carrying Out the Invention

[0008] Embodiments of the present invention will be described with reference to the drawings. With reference to FIGS. 1 to 9(B), the physical configuration of the sewing machine 1 will be described. The sewing machine 1 of the present embodiment is a sewing machine having a function of facilitating curved sewing by mechanically changing the pressing force applied to the presser foot 5 at a predetermined timing while the needle bar 31 of the sewing machine 1 reciprocates once in the vertical direction. The sewing machine 1 has a configuration in which the pressing force applied to the presser foot 5 can be easily switched between a pressing force suitable for curved sewing and a pressing force suitable for normal (straight) sewing. The vertical direction, lower right, upper left, lower left, and upper right in FIG. 1 are the vertical direction, right side, left side, front, and rear of the sewing machine 1 to which the pressing device 9 is attached, respectively. The extending direction of the leg post 12 is the vertical direction of the sewing machine 1. The extending directions of the bed 11 and the arm 13 from the leg post 12 are the left direction.

[0009] As shown in FIG. 1, the sewing machine 1 includes a bed 11, a leg post 12, an arm 13, and a head 14. The bed 11 is a base of the sewing machine 1 extending in the left-right direction and includes a needle plate 3. The needle plate 3 is provided on the upper surface of the bed 11. The needle plate 3 is a horizontally extending plate-like member, and a needle hole 25 through which a sewing needle 35 described later is inserted and an opening 26 extending in the front-rear direction are formed. The bed 11 includes a feed tooth 19, a bobbin mechanism 20 shown in FIG. 6, and a feed mechanism 23 below the needle plate 3. The feed tooth 19 projects from and retracts into the opening 26 formed in the needle plate 3 and feeds the workpiece C placed on the needle plate 3. The feed mechanism 23 conveys the workpiece C backward or forward by driving the feed tooth 19 in response to the drive of the sewing machine motor 2 described later. As shown in FIG. 6, the bobbin mechanism 20 includes a lower shaft 21 and a horizontal bobbin 22. The horizontal bobbin 22 rotates in response to the rotation of the lower shaft 21 and twists the upper thread (not shown) around the lower thread (not shown) below the needle plate 3.

[0010] As shown in FIG. 1, the leg post 12 is erected upward from the right end of the bed 11. Inside the upper part of the leg post 12, a sewing machine motor 2 is provided. An LCD 15 is provided on the front surface of the leg post 12. A switch 16 is provided below the LCD 15. A pulley 28 is provided on the right surface of the leg post 12.

[0011] The arm 13 extends leftward from the upper end of the leg post 12 facing the bed 11. The head 14 is a connecting part to the left tip of the arm 13. The head 14 is provided with a balance 36, a needle bar 31, a needle bar mechanism (not shown), a presser bar 8, an adjustment mechanism 68, etc. The balance 36 pulls up the upper thread wound around the bobbin by the lower thread in response to the drive of the sewing machine motor 2. The needle bar 31 can be equipped with a sewing needle 35 at its lower end and moves in the vertical direction in response to the drive of the sewing machine motor 2. A needle holder 36 is fixed to the lower end of the needle bar 31. The needle holder 36 removably fixes the sewing needle 35. The needle bar mechanism moves the needle bar 31 in the vertical direction in response to the drive of the sewing machine motor 2. The needle bar 31 also moves in the vertical direction when the pulley 28 is rotated by the user.

[0012] The presser bar 8 extends vertically behind the needle bar 31 and moves in the vertical direction in synchronization with the drive of the sewing machine motor 2, more specifically, the feed teeth 19. As shown in FIG. 2(A), the presser bar 8 is provided with a presser spring 81, a presser bar holder 82, and a lever 90. The presser spring 81 is a coil spring externally inserted into the presser bar 8. The presser bar holder 82 is fixed to the presser bar 8 and contacts the lower end of the presser spring 81 to define the lower end position of the presser spring 81. The presser spring 81 can bias the presser bar 8 downward via the adjustment part 65 and the presser bar holder 82. As shown in FIG. 3(A), the presser bar holder 82 has a housing part 85 that is recessed downward by a first length L1 for housing the lower end part of the adjustment spring 84. The adjustment spring 84 has a smaller biasing force than the presser spring 81. The adjustment spring 84 in this example is a coil spring. The adjustment spring 84 is housed in the housing part 85 in a state of being inserted through the presser bar 8. In the vertical direction, the lower end of the adjustment spring 84 is defined by the bottom surface of the housing part 85. The upper end of the adjustment spring 84 is defined by an adjustment part 65, which will be described later, arranged above the presser bar holder 82.

[0013] As shown in FIG. 2(A), the lever 90 manually switches the position of the presser bar 8 in the up-down direction. The lever 90 includes an axis 91, protrusions 92 and 93, and an operating part 94. The axis 91 is provided inside the head 14. The protrusions 92 and 93 are parts that protrude away from the axis 91 in the vicinity of the axis 91. The operating part 94 is the part furthest from the axis 91. By operating the operating part 94 with an operating object such as a finger, the user can rotate the lever 90 around the axis 91 in a clockwise or counterclockwise direction as viewed from the front, and switch the presser bar 8 between the raised position and the lowered position. FIGS. 2(A) to 7 show a state in which the operating part 94 is disposed below the axis 91 and the presser bar 8 is in the lowered position. When the operating part 94 is rotated counterclockwise when viewed from the front from the state shown in Fig. 6 and positioned upper right relative to the shaft part 91, the convex part 93 of the lever 90 comes into contact with the underside 83 of the presser bar bracket 82, moving the presser bar 8 to the raised position. Fig. 8 shows a state in which the operating part 94 is positioned upper right relative to the shaft part 91 and the presser bar 8 is in the raised position. With the presser bar 8 in the raised position, the user performs the work of placing or retrieving the workpiece C.

[0014] As shown in FIG. 3(A), a hole 86 is formed in the lower end of the presser bar 8, penetrating it in the left-right direction. The presser device 9 is removably attached to the lower end of the presser bar 8 by a screw 41 inserted through the hole 86. The presser device 9 supports the presser foot 5 so that it can swing about a shaft 53 extending in the left-right direction. The presser foot 5 is a rectangular plate that is long in the front-rear direction in a plan view. The front and rear ends of the presser foot 5 are each curved upward. As shown in FIG. 1, a notch 59 is formed in the front of the presser foot 5. When the presser device 9 that supports the presser foot 5 is attached to the lower end of the presser bar 8 and the sewing machine 1 is driven, the sewing needle 35 is inserted into the rear end of the notch 59. When the presser bar 8 is in the lowered position, the presser foot 5 comes into contact with the workpiece C placed on the needle plate 3 and presses the workpiece C downward. In this example, the sewing machine 1 can switch between changing and not changing the pressure transmitted to the presser foot 5 while the needle bar 31 of the sewing machine 1 makes one upward and downward reciprocating movement by operating the change member 70 of the adjustment mechanism 68 described later.

[0015] As shown in FIGS. 2(A) and 5(A), the adjustment mechanism 68 includes an adjustment part 65, a regulation part 67, and a changing member 70. The adjustment part 65 is movable in the vertical direction and defines the lower end of the pressing spring 81 and the upper end of the adjustment spring 84. The adjustment part 65 is formed, for example, by bending a metal plate. The adjustment part 65 is plate-shaped and has a first insertion part 42 through which a changing axis 66 of the changing member 70 described later is inserted and a second insertion part 43 through which the pressing bar 8 is inserted. The adjustment part 65 includes a first wall 61, a second wall 62, a third wall 63, and a fourth wall 64. The first wall 61 is plate-shaped and extends horizontally to the left of the pressing bar 8. The first insertion part 42 is formed in the first wall 61. The first insertion part 42 is a circular hole in plan view that penetrates the first wall 61 in the vertical direction. The first wall 61 defines the lower end of the movement range of the adjustment part 65 by contacting the regulation part 67. The second wall 62 is provided below the first wall 61 and is plate-shaped and extends horizontally to the right of the first wall 61. The second insertion part 43 is formed in the second wall 62. The second insertion part 43 is a circular hole in plan view that penetrates the second wall 62 in the vertical direction and through which the pressing bar 8 is inserted. The third wall 63 connects the first wall 61 and the second wall 62 in the vertical direction. The third wall 63 is plate-shaped and extends vertically to the left of the pressing bar 8 and connects the right end of the first wall 61 and the second wall 62. The first wall 61, the second wall 62, and the third wall 63 of the adjustment part 65 have a crank shape that is Z-shaped in front view.

[0016] The fourth wall 64 is connected to the third wall 63 and extends parallel to the pressing bar 8. The fourth wall 64 extends rightward from the rear end portion of the third wall 63. In the left-right direction, the left end portion of the fourth wall 64 is located to the left of the pressing bar 8, and the right end portion of the fourth wall 64 is located to the right of the pressing bar 8. As shown in FIGS. 2(A) and 4(A), the fourth wall 64 has a pair of upper and lower pins 78 protruding rearward. A plate-like portion 100 extending parallel to the fourth wall 64 is provided behind the fourth wall 64. The extending ranges of the plate-like portion 100 in the vertical direction and the left-right direction are larger than the extending ranges of the fourth wall 64 in the vertical direction and the left-right direction. Slits 101 and 102 extending in the vertical direction and penetrating in the front-rear direction are formed in the plate-like portion 100. The slit 101 is formed behind the pressing bar 8. The pair of pins 78 are inserted into the slit 101 of the plate-like portion 100. The slit 101 guides the vertical movement of the adjustment portion 65. The slit 102 is formed behind the change axis 66 and above the slit 101. The plate-like portion 100 further includes insertion portions 103 and 104 in which holes (not shown) penetrating in the vertical direction are formed. The insertion portions 103 and 104 are portions formed by bending the plate-like portion 100 forward, and the change axis 66 is inserted into the holes. A regulating member 75 is fixed to the upper left portion of the plate-like portion 100 by a screw 77. The regulating member 75 is a leaf spring extending in the left-right direction. The right end portion of the regulating member 75 is provided with a convex portion 76 protruding forward. The convex portion 76 is a portion where the leaf spring is bent into a V shape in plan view.

[0017] As shown in FIG. 2(A), when the regulating portion 67 comes into contact with the adjustment portion 65, the regulating portion 67 restricts the transmission of the biasing force of the pressing spring 81 to the pressing bar 8. The regulating portion 67 is in the shape of a rectangular parallelepiped fixed to the lower end portion of the change axis 66. The regulating portion 67 is disposed below the first wall 61 of the adjustment portion 65 and contacts and separates from the lower surface of the first wall 61 to limit the movement range of the adjustment portion 65.

[0018] As shown in FIGS. 2(A) to 5(B), the changing member 70 includes a changing shaft 66, a first member 71, a second member 72, an abutting portion 73, a first stopper 45, a second stopper 46, and a lid 74. The changing shaft 66 is a shaft-shaped member that extends parallel to the pressing bar 8 on the left side of the pressing bar 8 and supports the adjusting portion 65 so as to be movable in the vertical direction. The changing shaft 66 is inserted into the first insertion portion 42 of the first wall 61. The changing shaft 66 includes a contact portion 69 and a shaft 49. As shown in FIG. 5(A), the contact portion 69 is a rod-shaped member that is provided at the upper end of the changing shaft 66 and extends perpendicular to the changing shaft 66. The contact portion 69 extends forward from the changing shaft 66. The shaft 49 is a rod-shaped member that is provided below the contact portion 69 and extends perpendicular to the changing shaft 66. As shown in FIG. 4(A), the shaft 49 extends rearward from the changing shaft 66 and is inserted into the slit 102. The slit 102 guides the vertical movement of the changing shaft 66 and restricts the changing shaft 66 from rotating around the axis extending in the vertical direction.

[0019] The first member 71 has a first surface 51 that extends in the horizontal direction perpendicular to the vertical direction. The first surface 51 is exposed outside the cover 17. The vertical position of the first surface 51 in the present embodiment is substantially the same as the vertical position of the upper surface of the cover 17 of the sewing machine 1. Among the upper surface of the cover 17, the portion adjacent to the first surface 51 in the left-right direction, which is the longitudinal direction of the arm 13, extends horizontally in parallel with the first surface 51. The changing shaft 66 extends parallel to the pressing bar 8 and is connected to the restricting portion 67. The first member 71 has a hole 56 through which the changing shaft 66 is inserted, and the hole 56 penetrating in the vertical direction is formed. The first member 71 is a disk-shaped portion in plan view that is externally inserted into the changing shaft 66. The first member 71 includes a cylindrical portion 87, a flange 88, a dial 89, and a cylindrical portion 95. On the outer periphery of the cylindrical portion 87, a recess 80 (see FIG. 3(B)) that extends in the vertical direction and is recessed toward the changing shaft 66 is formed. The flange 88 projects horizontally from the lower end of the cylindrical portion 87. The outer periphery of the flange 88 is circular in plan view.

[0020] The dial 89 has a diameter smaller than that of the flange 88. The dial 89 is provided, on its outer peripheral portion, with a plurality of vertically extending concave portions 79 that are recessed toward the modification axis 66. One of the plurality of concave portions 79 of the first member 71 is detachably engaged with a convex portion 76 of a restricting member 75 provided behind the modification member 70. The restricting member 75 restricts the rotational movement of the first member 71 and fixes the modification member 70 at an arbitrary position. The cylindrical portion 95 extends downward from the dial 89 in a cylindrical shape. The diameter of the cylindrical portion 95 is shorter than the diameter of the cylindrical portion 87.

[0021] The first member 71 is an abutting portion 73 that abuts against the abutting portion 69, and has an abutting portion 73 that changes the vertical position of the restricting portion 67 by changing the abutting position against the abutting portion 69. As shown in FIG. 5(A), the abutting portion 73 is a cam surface of an end face cam that extends in a spiral shape centered on the modification axis 66 along the inner circumference of the second member 72. The abutting portion 73 abuts against the abutting portion 69 of the modification axis 66. The lower end of the cylindrical portion 95 of the first member 71 abuts against the upper surface of the insertion portion 103 of the plate-like portion 100. The first member 71 is sandwiched in the vertical direction by the abutting portion 69 of the modification axis 66 and the insertion portion 103 of the plate-like portion 100. Therefore, the vertical position of the first member 71 is a fixed position.

[0022] As shown in FIGS. 2(A) to 5(B), the second member 72 is a hole 55 through which the change axis 66 is inserted, and is cylindrical with a hole 55 formed therethrough in the vertical direction. The second member 72 has a cylindrical portion 57 and a flange 58 protruding horizontally from the lower end of the cylindrical portion 57. The second member 72 is movably supported with respect to the first member 71 on the change axis 66. The second member 72 is movable in the vertical direction. The second member 72 is exposed outside the cover 17. The second member 72 extends horizontally and has a second surface 52 facing the first surface 51. The second surface 52 is the lower surface of the second member 72 and has a larger area than the upper surface 54 of the second member 72. The second surface 52 is the lower surface of the flange 58. The upper surface 54 is the upper surface of the cylindrical portion 57. The area of the second surface 52 is larger than the area of the upper surface 50 of the lid 74 covering the upper surface 54 of the second member 72. The diameter of the outer periphery of the second surface 52 is larger than the diameter of the outer periphery of the upper surface 54. The diameter of the outer periphery of the second surface 52 is the same as the diameter of the outer periphery of the flange 88 of the first member 71. A recess 47 (see FIG. 9), which is circular in plan view and recessed upward, is formed in the second surface 52. On the outer periphery of the recess 47, a convex portion 48 protruding toward the hole 55 and extending in the vertical direction is provided. The cylindrical portion 87 of the first member 71 fits into the recess 47. The convex portion 48 engages with a recess 80 formed in the cylindrical portion 87 of the first member 71. Therefore, the second member 72 rotates around the change axis 66 together with the first member 71.

[0023] As shown in FIG. 9, the first stopper 45 is a pin inserted through the change axis 66 below the second member 72. The second stopper 46 is fixed above the first stopper 45. The second stopper 46 fixes the second member 72 to the change axis 66 in the vertical direction by narrowly pressing the second member 72 together with the first stopper 45. The second stopper 46 of this example is a retaining ring. The second stopper 46 abuts against the upper surface 54 of the second member 72 from above and is externally inserted into the change axis 66. The second member 72 is rotatably installed with respect to the change axis 66 by being narrowly pressed by the first stopper 45 and the second stopper 46.

[0024] As shown in FIGS. 4(A) and 4(B), the regulating part 67 moves vertically in response to the vertical movement of the second member 72. The regulating part 67 moves vertically together with the changing axis 66 in response to the rotation of the second member 72. The regulating part 67 moves vertically by the amount of vertical movement of the second member 72. The lid 74 covers the second member 72 from above. The lid 74 is detachably engaged with the second member 72 and can rotate together with the second member 72.

[0025] The changing member 70 changes the vertical position of the regulating part 67 according to the distance between the first member 71 and the second member 72. More specifically, the changing member 70 changes the vertical position of the regulating part 67 according to the vertical distance between the first surface 51 and the second surface 52. The changing member 70 functions as a dial that can rotate about the changing axis 66 in plan view. Specifically, when the user changes the vertical position of the regulating part 67, the user operates the second member 72 of the changing member 70 that is exposed outside the cover 17 of the sewing machine 1. The user may remove the cover 17 of the sewing machine 1 and operate the first member 71. The user places the workpiece C between the first surface 51 of the first member 71 and the second surface 52 of the second member 72, and rotates the second member 72 so that the second surface 52 abuts against the upper surface of the workpiece C. When the first member 71 is rotated, the second member 72 also rotates together with the first member 71. Since the shaft 49 of the changing axis 66 is inserted into the slit 102, the changing axis 66 does not rotate in response to the rotation of the changing member 70. At this time, the portion of the abutted part 73 that abuts against the abutting part 69 can be changed, and the vertical position of the abutting part 69 is changed. In this way, the abutting part 69 moves vertically according to the vertical position of the portion of the abutted part 73 against which the abutting part 69 abuts. In response to the user's rotation operation of the changing member 70, the changing axis 66 moves vertically while being guided by the slit 102.

[0026] In this way, by changing the contact position where the contacted portion 73 contacts the contact portion 69, the vertical position of the restricting portion 67 fixed to the lower end portion of the changing shaft 66 is changed. The lower end of the movement range of the restricting portion 67 is defined by an insertion portion 104 through which the changing shaft 66 is inserted below the restricting portion 67. The rotational positions of the first member 71 and the second member 72 are fixed when the convex portion 76 engages with any one of a plurality of concave portions 79 formed at the lower end portion of the first member 71. In this manner, the vertical position of the restricting portion 67 is changed to a position corresponding to the thickness of the workpiece C to be sewn. The user can remove the workpiece C to be sewn from between the first member 71 and the second member 72, place the workpiece C to be sewn on the needle plate 3, and form a seam in the workpiece C to be sewn, so that the vertical position of the restricting portion 67 is adjusted according to the thickness of the workpiece C to be sewn, and a seam can be formed in the workpiece C to be sewn.

[0027] Under the condition that the presser bar holder 82 and the lever 90 are vertically separated, the vertical positions of the presser bar holder 82 and the presser bar 8 are changed according to the vertical position of the feed teeth 19. The presser device 9 operates the changing member 70 to adjust the vertical position of the restricting portion 67 to a position where the first wall 61 of the adjusting portion 65 contacts the restricting portion 67 while the needle bar 31 of the sewing machine 1 makes a single reciprocation in the vertical direction. While the needle bar 31 of the sewing machine 1 makes a single reciprocation in the vertical direction, when the first wall 61 of the adjusting portion 65 contacts the restricting portion 67 and the adjusting portion 65 can no longer move downward, the second wall 62 of the adjusting portion 65 and the presser bar holder 82 are vertically separated, and the biasing force of the presser spring 81 is no longer transmitted to the presser bar holder 82. The biasing force of the adjusting spring 84 is transmitted to the presser bar holder 82.

[0028] With reference to FIGS. 2(A) to 7, a case where the vertical position of the regulating portion 67 is changed under the condition that the pressing bar 8 is arranged at the lowered position will be described. As shown in FIGS. 2(A), 3(A), 4(A), 5(A), 6, and 9(A), when the pressing force applied to the presser foot 5 is set to a pressing force suitable for normal sewing, the user arranges the regulating portion 67 at the reference position under the condition that the upper end of the feed tooth 19 is located above the needle plate 3 and the workpiece C is not arranged between the needle plate 3 and the presser foot 5 (first condition F1). In the first condition F1, the presser bar holder 82 is separated from the lever 90 in the vertical direction and abuts against the second wall 62 of the adjusting portion 65. In the first condition F1, the adjusting spring 84 is in the most contracted state in the vertical direction, and the second length L2 of the adjusting spring 84 in the vertical direction is equal to or less than the first length L1 of the accommodating portion 85 that accommodates the lower end portion of the adjusting spring 84 in the vertical direction. In the first condition F1, when sewing is performed with the workpiece C arranged between the needle plate 3 and the presser foot 5, the urging force from the presser spring 81 is always transmitted to the presser foot 5 while the needle bar 31 of the sewing machine 1 makes one reciprocation in the vertical direction.

[0029] As shown in FIGS. 2(B), 3(B), 4(B), 5(B), 7, and 9(B), when the pressing force applied to the presser foot 5 is set to a pressing force suitable for curved sewing, the user operates the changing member 70 from the first condition F1 to raise the regulating portion 67 by an amount corresponding to the thickness of the workpiece C (for example, 4 mm) from the reference position (second condition F2). In the second condition F2, the presser bar holder 82 is spaced apart from the lever 90 in the vertical direction and is also spaced apart from the second wall 62 of the adjusting portion 65 in the vertical direction. In the second condition F2, when sewing is performed with the workpiece C having a thickness of 4 mm disposed between the needle plate 3 and the presser foot 5, during one reciprocation of the needle bar 31 of the sewing machine 1 in the vertical direction, the urging force from the presser spring 81 is transmitted to the presser foot 5 during the period when the regulating portion 67 and the first wall 61 of the adjusting portion 65 are spaced apart in the vertical direction. On the other hand, during the period when the regulating portion 67 and the first wall 61 of the adjusting portion 65 are in contact with each other in the vertical direction, the urging force from the presser spring 81 is not transmitted to the presser foot 5, and the urging force of the adjusting spring 84 is transmitted to the presser foot 5. The user can change the pressing force applied to the workpiece C during one reciprocation of the needle bar 31 of the sewing machine 1 in the vertical direction by operating the changing member 70 according to the thickness of the workpiece C and adjusting the vertical position of the regulating portion 67.

[0030] Referring to FIG. 8, the case where the presser bar 8 is disposed at the raised position will be described. As shown in FIG. 8, when the lever 90 is operated from the first condition F1 of FIG. 6 and the convex portion 93 of the lever 90 is brought into contact with the presser bar holder 82, the presser bar holder 82 and the presser bar 8 are pushed upward by the convex portion 93, and the presser foot 5 is spaced apart from the needle plate 3 in the vertical direction. In this state, the user performs the operation of disposing the workpiece C between the needle plate 3 and the presser foot 5, and the operation of attaching or detaching the pressing device 9 to the lower end of the presser bar 8.

[0031] Referring to FIG. 10, the relationship between the vertical position of the needle bar 31, the vertical position of the feed dog 19, the vertical position of the presser bar holder 82, the pressing force applied by the presser foot 5 to the workpiece C, and the vertical distance between the regulating portion 67 and the first wall 61 of the adjusting portion 65 in accordance with the rotational angle of the sewing machine motor 2 will be described. In the sewing machine 1 of the present embodiment, when the sewing machine motor 2 makes one revolution, the needle bar 31 of the sewing machine 1 reciprocates once in the vertical direction. In the "presser foot pressing force" of FIG. 10, the minute change amount due to the displacement amount of the adjusting spring 84 accompanying the vertical movement of the feed dog 19 and the minute change amount due to the displacement amount of the presser spring 81 are ignored. In FIG. 10, the pressing force applied to the presser foot 5 in the period P1 is set to 100, and the pressing force applied to the presser foot 5 in the period P2 is represented. The period P1 is a period in which the first wall 61 of the adjusting portion 65 and the regulating portion 67 are separated from each other in the vertical direction. The period P2 is a period in which the first wall 61 of the adjusting portion 65 and the regulating portion 67 are in contact with each other in the vertical direction. The pressing force applied to the presser foot 5 in the period P2 is smaller than the pressing force applied to the presser foot 5 in the period P1. In the period P2, the presser bar holder 82 descends by the biasing force of the adjusting spring 84 to a position where the presser foot 5 contacts the workpiece C downward with respect to the second wall 62 of the adjusting portion 65. Thereby, the second wall 62 and the presser bar holder 82 are separated from each other in the vertical direction. In the period P1, the presser foot 5 is lifted by the feed dog 19, and the presser bar 8 is pushed upward. As a result, the presser bar holder 82 moves upward against the biasing force of the adjusting spring 84 and comes into contact with the second wall 62 in the vertical direction. Since the adjusting portion 65 can move upward, the presser bar holder 82 moves upward together with the adjusting portion 65 having the second wall 62.

[0032] That is, in the first situation where the tooth upper end 18, which is the upper end of the feed tooth 19, is above the plate upper end 27, which is the upper end of the needle plate 3, and the adjustment part 65 is separated from the regulating part 67, the adjustment part 65 and the presser bar holder 82 come into contact with each other, and the biasing force of the presser spring 81 is transmitted to the presser bar 8. In the first situation, the sewing needle 35 is positioned above the workpiece C. That is, while the sewing machine 1 is transporting the workpiece C in the transport direction by the feed tooth 19, the pressing force of the presser spring 81 is applied to the presser foot 5. Thereby, the sewing machine 1 can stably transport the workpiece C in the transport direction in a state where the workpiece C is firmly clamped in the vertical direction by the presser foot 5 and the feed tooth 19.

[0033] On the other hand, in the second situation where the tooth upper end 18 is below the plate upper end 27 and the adjustment part 65 abuts on the regulating part 67, the adjustment part 65 and the presser bar holder 82 are separated in the vertical direction, and the biasing force of the presser spring 81 is not transmitted to the presser bar 8. The second situation includes the period during which the sewing needle 35 penetrates the workpiece C. Thereby, the sewing machine 1 can make the force applied to the presser foot 5 during the period P2 when the sewing needle 35 penetrates the workpiece C smaller than that of a conventional sewing machine. Therefore, the sewing machine 1 can change the orientation of the workpiece C being sewn with respect to the needle plate 3 more easily than a conventional sewing machine, and can sew a curved portion more easily.

[0034] In the above embodiment, the sewing machine 1, the sewing machine motor 2, the needle plate 3, the presser foot 5, the presser bar 8, the cover 17, the tooth upper end 18, the feed tooth 19, the needle hole 25, the opening 26, the plate upper end 27, the needle bar 31, and the sewing needle 35 are each an example of the sewing machine, the sewing machine motor, the needle plate, the presser foot, the presser bar, the cover, the tooth upper end, the feed tooth, the needle hole, the opening, the plate upper end, the needle bar, and the sewing needle of the present invention. The first stopper 45, the second stopper 46, the first surface 51, the second surface 52, the upper surface 54, the hole 55, the adjustment part 65, the change shaft 66, the regulating part 67, the contact part 69, the change member 70, the first member 71, the second member 72, the contacted part 73, the presser spring 81, and the adjustment spring 84 are each an example of the first stopper, the second stopper, the first surface, the second surface, the upper surface, the hole, the adjustment part, the change shaft, the regulating part, the contact part, the change member, the first member, the second member, the contacted part, the presser spring, and the adjustment spring.

[0035] The sewing machine 1 of the above embodiment includes a sewing machine motor 2, a needle bar 31, a needle plate 3, a feed dog 19, a presser bar 8, a presser bar holder 82, an adjustment unit 65, a presser spring 81, a regulating unit 67, and a changing member 70. The needle bar 31 can have a sewing needle 35 attached to its lower end and moves in the vertical direction in response to the drive of the sewing machine motor 2. The needle plate 3 has a needle hole 25 through which the sewing needle 35 is inserted. The feed dog 19 projects in and out of an opening 26 formed in the needle plate 3 in response to the drive of the sewing machine motor 2 and feeds the workpiece C placed on the needle plate 3. The presser bar 8 can have a presser foot 5 attached to its lower end and moves in the vertical direction in synchronization with the drive of the feed dog 19. The presser bar holder 82 is fixed to the presser bar 8. The adjustment unit 65 is movable in the vertical direction. The presser spring 81 can bias the presser bar 8 downward via the adjustment unit 65 and the presser bar holder 82. The regulating unit 67 restricts the transmission of the biasing force of the presser spring 81 to the presser bar 8 when it comes into contact with the adjustment unit 65. The changing member 70 has a first member 71 and a second member 72 movably supported with respect to the first member 71, and changes the vertical position of the regulating unit 67 according to the distance between the first member 71 and the second member 72. The presser bar 8 is such that the upper end of the teeth 18, which is the upper end of the feed dog 19, is above the upper end of the plate 27, which is the upper end of the needle plate 3, and in the first situation where the adjustment unit 65 is separated from the regulating unit 67, the adjustment unit 65 and the presser bar holder 82 come into contact, and the biasing force of the presser spring 81 is transmitted to the presser bar 8. In the second situation where the upper end of the teeth 18 is below the upper end of the plate 27 and the adjustment unit 65 comes into contact with the regulating unit 67, the adjustment unit 65 and the presser bar holder 82 are separated in the vertical direction, and the biasing force of the presser spring 81 is not transmitted to the presser bar 8.

[0036] The sewing machine 1 can allow the user to adjust the timing at which the biasing force of the presser spring 81 is transmitted or not transmitted to the presser bar 8 by a relatively simple operation of changing the distance between the first member 71 and the second member 72. Therefore, the sewing machine 1 contributes to making it easier than before to adjust the timing of changing the biasing force applied to the presser foot 5 attached to the lower end of the presser bar 8 according to the workpiece C in conjunction with the sewing machine motor 2.

[0037] The sewing machine 1 is disposed below the adjustment unit 65 and includes an adjustment spring 84 that biases the presser bar 8 downward via the presser bar holder 82 at least in the second situation. The biasing force of the adjustment spring 84 is smaller than the biasing force of the presser spring 81. The sewing machine 1 can bias the presser foot 5 attached to the lower end of the presser bar 8 downward with the biasing force of the adjustment spring 84 that is smaller than the biasing force of the presser spring 81 at least in the second situation. Therefore, the sewing machine 1 contributes to realizing stable sewing by eliminating the situation (period) in which the presser foot 5 is completely released from force.

[0038] The first member 71 has a first surface 51 that extends in a horizontal direction orthogonal to the vertical direction. The second member 72 extends in the horizontal direction and has a second surface 52 that faces the first surface 51. The changing member 70 changes the vertical position of the restricting portion 67 according to the vertical distance between the first surface 51 and the second surface 52. The first member 71 and the second member 72 of the sewing machine 1 contribute to making it easier to perform the operation of adjusting the distance between the first surface 51 and the second surface 52 according to the workpiece C compared to the case where the first surface 51 and the second surface 52 are surfaces that extend in the vertical direction.

[0039] The second member 72 is movable in the vertical direction. The vertical position of the first member 71 is a fixed position. The sewing machine 1 contributes to making the operation of adjusting the timing of changing the biasing force applied to the presser foot 5 provided at the lower end of the presser bar 8 according to the workpiece C in conjunction with the sewing machine motor 2 into a relatively simple operation of moving the position of the first member 71 in the vertical direction.

[0040] The restricting portion 67 moves in the vertical direction according to the vertical movement of the second member 72. The sewing machine 1 contributes to making the operation of adjusting the timing of changing the biasing force applied to the presser foot 5 provided at the lower end of the presser bar 8 according to the workpiece C in conjunction with the sewing machine motor 2 into a relatively simple operation of moving the second member 72 in the vertical direction.

[0041] The second surface 52 is the lower surface of the second member 72 and has a larger area than the upper surface 54 of the second member 72. The second member 72 of the sewing machine 1 contributes to making it easier to check the position of the second surface 52 and to adjust the distance between the first surface 51 and the second surface 52 as compared with the case where the area of the second surface 52 is less than or equal to the area of the upper surface 54 of the second member 72.

[0042] The changing member 70 has a changing shaft 66 that extends parallel to the presser bar 8 and is connected to the regulating portion 67. The second member 72 is rotatably installed with respect to the changing shaft 66. The regulating portion 67 moves vertically together with the changing shaft 66 in accordance with the rotation of the second member 72. The second member 72 and the changing shaft 66 of the sewing machine 1 contribute to making the configuration of the changing member 70 relatively simple.

[0043] A hole 55 through which the changing shaft 66 is inserted is formed in the second member 72. The sewing machine 1 includes a first stopper 45 and a second stopper 46. The first stopper 45 is inserted through the changing shaft 66 below the second member 72. The second stopper 46 is fixed above the first stopper 45 and fixes the second member 72 with respect to the changing shaft 66 in the vertical direction by narrowly pressing the second member 72 together with the first stopper 45. The first stopper 45 and the second stopper 46 of the sewing machine 1 contribute to realizing, with a relatively simple configuration, a configuration in which the second member 72 is rotatable with respect to the changing shaft 66 and the vertical position with respect to the changing shaft 66 is fixed.

[0044] The sewing machine 1 includes a contact portion 69 provided on the changing shaft 66. The first member 71 has a contacted portion 73 that contacts the contact portion 69 and changes the vertical position of the regulating portion 67 by changing the contact position where it contacts the contact portion 69. The contact portion 69 and the contacted portion 73 of the sewing machine 1 contribute to realizing, with a relatively simple configuration, a configuration in which the regulating portion 67 is moved vertically together with the changing shaft 66 in accordance with the rotation of the second member 72.

[0045] The sewing machine 1 is provided with a cover 17 that covers the sewing machine motor 2. The first surface 51 and the second member 72 are exposed outside the cover 17. The sewing machine 1 is easier to perform the operation of adjusting the distance between the first surface 51 and the second surface 52 according to the workpiece C to be sewn, compared with the case where the first surface 51 and the second member 72 are arranged inside the cover 17. The sewing machine 1 can easily adjust the distance between the first surface 51 and the second surface 52 to a distance corresponding to the thickness of the workpiece C to be sewn by sandwiching the workpiece C to be sewn between the first surface 51 and the second surface 52. The first surface 51 of the present embodiment extends in the horizontal direction, and the vertical position of the first surface 51 is the same as the vertical position of the upper surface of the cover 17. Therefore, compared with the case where the vertical position of the first surface 51 is different from the vertical position of the upper surface of the cover 17, it is easier to perform the operation of sandwiching the workpiece C to be sewn between the first surface 51 and the second surface 52.

[0046] The sewing machine of the present invention is not limited to the above-described embodiment, and various modifications may be made without departing from the gist of the present invention. For example, the following modifications may be appropriately added.

[0047] The configurations of the sewing machine 1 and the presser device 9 may be appropriately changed. The sewing machine 1 may be an industrial sewing machine. The conveyance direction of the workpiece C by the sewing machine 1 may be appropriately changed.

[0048] The types, arrangements, etc. of the presser spring 81 and the adjustment spring 84 may be appropriately changed. The presser spring 81 and the adjustment spring 84 do not have to be externally inserted into the presser bar 8 respectively. The lower end portion of the adjustment spring 84 does not have to be housed in the housing portion 85. The second length L2 in the vertical direction in the state where the adjustment spring 84 is most contracted may be larger than the first length L1. The adjustment spring 84 may be omitted. The adjustment spring 84 only needs to be able to urge the presser bar 8 downward via the presser bar holder 82 at least in the case of the second situation. The configuration of the adjustment mechanism 68 may be appropriately changed.

[0049] The configuration of the changing member 70 may be changed as appropriate. The first member may have a first surface extending in the vertical direction, and the second member may face the first surface of the first member and have a second surface extending in the vertical direction. In this case, the changing member may include a conversion member such as a rack and pinion gear, a bevel gear, and a worm gear - worm wheel, and the conversion member may convert the horizontal movement between the first member and the second member into vertical movement to move the restricting portion 67 in the vertical direction. The vertical position of the second member 72 may be a fixed position, or the first member 71 provided below the second member 72 may be movable in the vertical direction. In that case, the changing shaft 66, the abutting portion 69, and the abutted portion 73 may be omitted, and the restricting portion 67 may move in the vertical direction according to the vertical movement of the first member 71.

[0050] The changing member 70 may include a changing shaft 66 as the second member and omit the second member 72. In this case, with the workpiece C placed on the first surface 51, the first member 71 is rotated around the changing shaft 66 and adjusted so that the upper surface of the workpiece C is located at a predetermined position of the changing shaft 66, whereby the restricting portion 67 may be moved to a vertical position corresponding to the thickness of the workpiece C. The predetermined position may be set as appropriate. For example, the upper end of the changing shaft 66 may be at the vertical position that becomes the upper surface of the workpiece C, or the first stopper 45 inserted through the changing shaft 66 may be at the position where it abuts against the upper surface of the workpiece C. When changing the distance between the first member 71 and the second member 72, it is not necessary to dispose the workpiece C between the first surface 51 and the second surface 52. For example, when setting the distance between the first member 71 and the second member 72 to a distance corresponding to a workpiece C with a known thickness, the distance between the first member 71 and the second member 72 of the sewing machine 1 may be measured and adjusted, or the distance between the first member 71 and the second member 72 of the sewing machine 1 may be adjusted by referring to the memory provided in the changing member 70.

[0051] The changing member 70 may be provided with a cam surface that guides a contact portion fixed to the changing shaft 66, or a contact portion composed of a cam surface and a cam groove or the like may be formed on the changing shaft 66, and the changing member 70 may be provided with a cam that contacts the contact portion of the changing shaft 66 as a contacted portion. The changing member 70 may have a configuration other than the contact portion and the contacted portion. For example, the changing member 70 may be composed of a pinion and a rack fixed to the changing shaft 66 and engaged with the pinion. The changing member 70 may be a dial or a lever or the like. The configuration of the restricting member 75 that restricts the rotation of the changing member 70 may be appropriately changed according to the configuration of the changing member 70. The arrangement of the changing member 70 with respect to the pressing bar 8 may be appropriately changed. The changing member 70 is preferably provided at a location where the user can easily operate and at a position that does not interfere with the sewing operation.

[0052] The second surface 52 may not be larger in area than the upper surface 54 of the second member 72. The changing shaft 66 may be omitted or may not extend parallel to the pressing bar 8. A hole 55 through which the changing shaft 66 is inserted may not be formed in the second member 72, and the second member 72 may not be rotatably installed with respect to the changing shaft 66. The sewing machine 1 may not include at least one of the first stopper 45 and the second stopper 46. The second member 72 may not be pinched between the first stopper 45 and the second stopper 46. The first surface 51 and the second member 72 may not be exposed outside the cover 17. The upper surface of the cover 17 may function as a substitute for the first surface 51, and the first member 71 may not be provided separately from the cover 17.

[0053] The shape of the adjusting portion 65 may be appropriately changed and may not be a crank shape such as a flat plate shape, a rectangular parallelepiped shape, or a spherical shape. The shape of at least one of the first wall 61 to the fourth wall 64 of the adjusting portion 65 may be changed, or at least one of the first wall 61 to the fourth wall 64 may be appropriately omitted. The configuration for changing the vertical position of the restricting portion 67 may be appropriately changed. The pressing bar holder 82 may not include the accommodating portion 85, or the second length L2 may be larger than the first length L1.

Explanation of Reference Numerals

[0054] 1: Sewing machine, 2: Sewing machine motor, 3: Needle plate, 5: Presser foot, 8: Presser bar, 17: Cover, 18: Tooth upper end, 19: Feed teeth, 25: Needle hole, 26: Opening, 27: Plate upper end, 31: Needle bar, 35: Sewing needle, 45: First stopper, 46: Second stopper, 51: First surface, 52: Second surface, 54: Upper surface, 55: Hole, 65: Adjustment part, 66: Change shaft, 67: Regulation part, 69: Contact part, 70: Change member, 71: First member, 72: Second member, 73: Contacted part, 81: Presser spring, 84: Adjustment spring

Claims

1. A sewing machine motor, a needle bar that can have a sewing needle attached to its lower end and moves in the vertical direction in response to the drive of the sewing machine motor, a needle plate in which a needle hole for inserting the sewing needle is formed, feed teeth that protrude and retract from an opening formed in the needle plate in response to the drive of the sewing machine motor and feed the workpiece placed on the needle plate, a presser bar that can have a presser foot attached to its lower end and moves in the vertical direction in synchronization with the drive of the feed teeth, a presser bar holder fixed to the presser bar, an adjustment part that can move in the vertical direction, a presser spring that can bias the presser bar downward via the adjustment part and the presser bar holder, a restricting part that restricts the transmission of the biasing force of the presser spring to the presser bar when it comes into contact with the adjustment part, comprising a first member and a second member that is movably supported with respect to the first member, and a changing member that changes the vertical position of the restricting part according to the distance between the first member and the second member, when the upper end of the teeth, which is the upper end of the feed teeth, is above the upper end of the plate, which is the upper end of the needle plate, and in a first situation where the adjustment part is separated from the restricting part, the adjustment part and the presser bar holder come into contact, and the biasing force of the presser spring is transmitted to the presser bar, a sewing machine characterized in that when the upper end of the teeth is below the upper end of the plate and in a second situation where the adjustment part comes into contact with the restricting part, the adjustment part and the presser bar holder are separated in the vertical direction, and the biasing force of the presser spring is not transmitted to the presser bar.

2. further comprising an adjustment spring that is disposed below the adjustment part and biases the presser bar downward via the presser bar holder at least in the second situation, The sewing machine according to claim 1, wherein the biasing force of the adjustment spring is smaller than the biasing force of the presser spring.

3. The first member has a first surface that extends in a horizontal direction orthogonal to the vertical direction, The second member extends in the horizontal direction and has a second surface facing the first surface, The sewing machine according to claim 1, wherein the changing member changes the vertical position of the restricting part according to the vertical distance between the first surface and the second surface.

4. The second member is movable in the vertical direction, The sewing machine according to claim 3, wherein the vertical position of the first member is a fixed position.

5. The sewing machine according to claim 4, wherein the regulating portion moves in the vertical direction in accordance with the vertical movement of the second member.

6. The sewing machine according to claim 5, wherein the second surface is the lower surface of the second member and has a larger area than the upper surface of the second member.

7. The changing member has a changing shaft that extends parallel to the presser bar and is connected to the regulating portion. The second member is rotatably installed with respect to the changing shaft. The sewing machine according to claim 3, wherein the regulating portion moves in the vertical direction together with the changing shaft in accordance with the rotation of the second member.

8. A hole through which the changing shaft is inserted is formed in the second member. A first stopper inserted through the changing shaft below the second member. The sewing machine according to claim 7, further comprising a second stopper that is fixed above the first stopper and fixes the second member with respect to the changing shaft in the vertical direction by narrowing and pressing the second member together with the first stopper.

9. The sewing machine further comprises a contact portion provided on the changing shaft. The sewing machine according to claim 8, wherein the first member is a contact portion that contacts the contact portion, and has the contact portion that changes the contact position with the contact portion to change the vertical position of the regulating portion.

10. The sewing machine further comprises a cover that covers the sewing machine motor. The sewing machine according to claim 3, wherein the first surface and the second member are exposed outside the cover.

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