It is a fabric advancement device of a sewing machine, placed near one or more sewing needles and suitable for the movement of the jaws.

A feed dog device of a sewing machine includes a driving unit, a needle plate unit, a feed dog unit, an up-down transmitting unit, a horizontal transmitting unit and a direction adjusting unit. The direction adjusting unit includes a stepper motor with a variable rotational speed controlled in accordance with a speed of the driving shaft of the driving unit, and a linkage mechanism actuatable by the stepper motor to be moved to different positions so as to interfere with a horizontal reciprocating motion by the horizontal transmitting unit such that the horizontal reciprocating motion cooperates with the up-down reciprocating motion by the up-down transmitting unit to bring the feed dog unit into performing a variable moving course.

A feed dog device of a sewing machine includes a driving unit, a needle plate unit, a feed dog unit, an up-down transmitting unit, a horizontal transmitting unit and a direction adjusting unit. The direction adjusting unit includes a stepper motor with a variable rotational speed controlled in accordance with a speed of the driving shaft of the driving unit, and a linkage mechanism actuatable by the stepper motor to be moved to different positions so as to interfere with a horizontal reciprocating motion by the horizontal transmitting unit such that the horizontal reciprocating motion cooperates with the up-down reciprocating motion by the up-down transmitting unit to bring the feed dog unit into performing a variable moving course.

A sewing machine includes a feed dog partially protruding out up and down from a throat plate to feed a workpiece, a sewing needle configured to perform stitch points on the workpiece by moving up and down, and a shuttle configured to capture an upper thread passed through the sewing needle below the throat plate to be entwined with a lower thread. The feed dog includes a top plate having teeth formed on an upper surface thereof, and a support portion to which a feed operation relative to the top plate is input. The top plate includes an insertion hole that the sewing needle penetrates up and down, and a pair of wall portions extending in an up-and-down direction respectively on one side and another side in a feed direction of the workpiece relative to the insertion hole on a lower surface side of the top plate.

A sewing machine according to the present invention includes: an upper shaft that drives a needle and a balance; a lower shaft that drives a hook and a feed dog; an upper and lower shaft belt that synchronizes rotation of the upper shaft with rotation of the lower shaft; and an idler unit that pushes an idler into the upper and lower shaft belt to change a tension side belt length, in which the idler unit includes a transmission mechanism connected to the upper shaft or the lower shaft, and a rotating body mechanism provided with the idler and having a rotating body that rotates in synchronization with the upper shaft or the lower shaft by the transmission mechanism, and a pushing amount of the idler into the upper and lower shaft belt is changed according to rotation of the rotating body.

A sewing machine having a device for manually changing a feed dog (10), including the feed dog (10) and a feed-dog holder (30). The feed-dog holder (30) is disposed in an arm bed (103) that is associated with the sewing machine, and the feed dog (10) is receivable in a clearance (31, 81) of the feed-dog holder (30). The feed dog (10) that is located in the clearance (31, 81) has a support face (15) which may be disposed parallel with the surface of a sewn-product support which may contain a needle-hole plate (113) or be configured as a needle-hole plate (113), the sewn-product support and/or the needle-hole plate (113) may at least partially be formed by the surface of the arm bed (103), and the support face (15) may be received in an opening (140) of the needle-hole plate (113). The feed dog (10) is fastenable in the clearance by a fastening element (40, 82, 83) or of a setting element (50) such that the support face (15) is alignable so as to be substantially parallel with the surface of the sewn-product support or of the needle-hole plate (113). The fastening element (40, 82, 83) or the setting element (50) is releasably held in the feed-dog holder (30).

A sewing machine having a device for manually changing a feed dog (10), including the feed dog (10) and a feed-dog holder (30). The feed-dog holder (30) is disposed in an arm bed (103) that is associated with the sewing machine, and the feed dog (10) is receivable in a clearance (31, 81) of the feed-dog holder (30). The feed dog (10) that is located in the clearance (31, 81) has a support face (15) which may be disposed parallel with the surface of a sewn-product support which may contain a needle-hole plate (113) or be configured as a needle-hole plate (113), the sewn-product support and/or the needle-hole plate (113) may at least partially be formed by the surface of the arm bed (103), and the support face (15) may be received in an opening (140) of the needle-hole plate (113). The feed dog (10) is fastenable in the clearance by a fastening element (40, 82, 83) or of a setting element (50) such that the support face (15) is alignable so as to be substantially parallel with the surface of the sewn-product support or of the needle-hole plate (113). The fastening element (40, 82, 83) or the setting element (50) is releasably held in the feed-dog holder (30).

Provided is a sewing machine capable of positioning feed dogs with a sufficient distance below the upper surface of a throat plate when the feed dogs are retracted. Feed dogs 3 protrude and retract from a throat plate 1. A horizontal feed drive unit 8 converts the rotation of a drive shaft 7 into a reciprocating motion in the horizontal direction and transmits the horizontal reciprocating motion to the feed dogs 3. A vertical drive unit 9 converts the rotation of the drive shaft 7 into a reciprocating motion in the vertical direction and transmits the vertical reciprocating motion to the feed dogs 3. A vertical position changing part moves turn-back points P at both ends of a forward path and a return path when the feed dogs 3 reciprocate in the horizontal direction below the throat plate 1.

In feed dog mounting/unmounting mechanism, lever is slidably provided to feed base in the front-rear direction, and is forced backward by a lever force-applying spring. Upon sliding lever rearward, fixing target portion of feed dog 22 is fixedly held by base-side fixing portion of feed base and lever-side fixing portion of lever arranged in the front-rear direction. Stopper is provided to feed base so as to be movable in the upper-lower direction, and holds lever. When feed dog is mounted, stopper is pressed downward by feed dog, which moves stopper so as to allow lever to slide. With this, lever is slid due to force applied by the lever force-applying spring, thereby allowing fixing target portion to be held, interposed between base-side fixing portion and lever-side fixing portion.

Provided is a sewing machine that can be reduced in size by employing a simple configuration for a feed dog drive device. A lateral feed drive unit (8) and a vertical drive unit (9) transmit rotation of a drive shaft (7) to a feed dog (3). The feed dog (3) is supported by a swingable feed base (5). A square piece (18) is provided at a lower end of a raising and lowering link (15) of the vertical drive unit (9). A guide member (19) including a guide groove (20) configured to guide the square piece (18) is disposed right under the feed base (5). An upper end of the raising and lowering link (15) is connected to a part of the feed base (5) between the swinging shaft (6) and the feed dog (3).