Abstract: A driving clutch device for a sewing machine includes a drive shaft, a passive member, a clutch seat, an actuating seat, a power unit, and a clutch member. Through fixing the passive member and the clutch seat onto the drive shaft, rotatably disposing the actuating seat, the drive shaft, and returnably disposing the clutch member to the clutch seat, the clutch seat and the actuating seat are able to move synchronously when the clutch member is in the engaged position, but not to move synchronously when the clutch member in the disengaged position, thereby achieving the driving and clutch controls only by the clutch member, the passive member, the clutch seat and the actuating seat. Therefore, the driving clutch device is simpler and the driving is more direct and instant, thereby reducing assembly costs and the error of action coordination.

Abstract: A driving clutch device for a sewing machine includes a drive shaft, a passive member, a clutch seat, an actuating seat, a power unit, and a clutch member. Through fixing the passive member and the clutch seat onto the drive shaft, rotatably disposing the actuating seat, the drive shaft, and returnably disposing the clutch member to the clutch seat, the clutch seat and the actuating seat are able to move synchronously when the clutch member is in the engaged position, but not to move synchronously when the clutch member in the disengaged position, thereby achieving the driving and clutch controls only by the clutch member, the passive member, the clutch seat and the actuating seat. Therefore, the driving clutch device is simpler and the driving is more direct and instant, thereby reducing assembly costs and the error of action coordination.

Abstract: A feed-dog stabilizing mechanism for a sewing machine essentially includes a support member and a drive source. The support member is disposed below a feed dog and driven to move by the drive source, so that the support member can push against the feed dog, and as a result, the height at which the fabric is bitten by the feed dog can be maintained during the course of fabric feeding to maintain the optimum feeding efficiency.

Abstract: A positioning device for rotating a movable tongue seat is essentially provided with a pin and a pin hole between a movable tongue seat and a cutter seat for driving the movable tongue seat. Rotating the positioning member can drive the movable tongue seat to move to a corresponding position, so that the movable tongue on the movable tongue seat can be extended and retracted from the top of the seat in an optimal position, and can be reliably controlled.

Abstract: A positioning device for rotating a movable tongue seat is essentially provided with a pin and a pin hole between a movable tongue seat and a cutter seat for driving the movable tongue seat. Rotating the positioning member can drive the movable tongue seat to move to a corresponding position, so that the movable tongue on the movable tongue seat can be extended and retracted from the top of the seat in an optimal position, and can be reliably controlled.

Abstract: A positioning structure for a movable tongue seat includes: an eccentric positioning member disposed between the movable tongue seat and the cutter seat, the eccentric positioning member is provided with a rotary end which is located toward one end of the cutter seat, wherein the eccentric positioning member rotates about the rotary end and is further provided with a drive end which is inserted in a slot of the movable tongue seat, the drive end and the rotary end are not coaxially aligned; and a pivot hole and a pivot provided between the movable tongue seat and the cutter seat, so that the movable tongue seat is able rotate on the cutter seat by rotating about the pivot. When the eccentric positioning member rotates about the rotary end, the drive end can push the movable tongue seat to rotate about the pivot to a desired position.

Abstract: A hollow pipe joint structure for a sewing machine includes a first hollow pipe, a second hollow pipe and an elastic member. The elastic member is sleeved onto the first hollow pipe and the second hollow pipe, and elastically squeezes against the first outer surface and the second outer surface of the first and second hollow pipes, respectively, to pull the first and second hollow pipes against each other, which makes assembly of the hollow pipes easier, quicker and no frequent maintenance is required.

Abstract: A knee operated lifting mechanism for a presser foot of a sewing machine is fixed on a body of the sewing machine, the body is provided with a presser-foot shaft, the knee operated lifting mechanism is drivingly connected to the presser-foot shaft, so as to consequently drive the presser foot to move up and down. The knee operated lifting mechanism includes a knee pushing device, a cable and a rotary member. The knee pushing device includes a knee pushing plate to be operated by a user. The cable is drivingly connected to the knee pushing plate to control the rotation of a drive shaft and the rotation of the presser-foot shaft as well, which consequently controls the upward and downward motion of the presser foot, and thus considerably simplifying the structure of the knee operated lifting mechanism.

Abstract: A sewing-thread pre-stress device for a sewing machine includes: a sewing-thread support, a pre-stress supply member, an abutting member and a top cover. The sewing-thread support includes an accommodating groove with a groove bottom. The pre-stress supply member is made of elastic material, provided in the accommodating groove, and has a folding portion which has two extension portions with one end connected to two sides of the folding portion. The abutting member is disposed on the pre-stress supply member, and the two abutting portions abut against the abutting member. The top cover is disposed on the abutting member and fixed to the sewing-thread support to define a thread space between the top cover and the abutting member for allowing a sewing thread to be inserted therethrough. The member is elastic and V-shaped, therefore the elastic force change is relatively small, which can provide the sewing thread an appropriate tension.

Abstract: A feed-dog stabilizing mechanism for a sewing machine essentially includes a support member and a drive source. The support member is disposed below a feed dog and driven to move by the drive source, so that the support member can push against the feed dog, and as a result, the height at which the fabric is bitten by the feed dog can be maintained during the course of fabric feeding to maintain the optimum feeding efficiency.

Abstract: A hollow pipe joint structure for a sewing machine includes a first hollow pipe, a second hollow pipe and an elastic member. The elastic member is sleeved onto the first hollow pipe and the second hollow pipe, and elastically squeezes against the first outer surface and the second outer surface of the first and second hollow pipes, respectively, to pull the first and second hollow pipes against each other, which makes assembly of the hollow pipes easier, quicker and no frequent maintenance is required.

Abstract: A knee operated lifting mechanism for a presser foot of a sewing machine is fixed on a body of the sewing machine, the body is provided with a presser-foot shaft, the knee operated lifting mechanism is drivingly connected to the presser-foot shaft, so as to consequently drive the presser foot to move up and down. The knee operated lifting mechanism includes a knee pushing device, a cable and a rotary member. The knee pushing device includes a knee pushing plate to be operated by a user. The cable is drivingly connected to the knee pushing plate to control the rotation of a drive shaft and the rotation of the presser-foot shaft as well, which consequently controls the upward and downward motion of the presser foot, and thus considerably simplifying the structure of the knee operated lifting mechanism.

Abstract: A cutting device for a sewing machine includes an upper-blade positioning device and a lower-blade positioning device. The upper-blade positioning device includes an upper blade upper blade fixed at a head portion of the upper-blade holder, and a spring and a restricting member sleeved on a body portion of the upper-blade holder. A restricting pin is engaged between an upper-blade drive member and the restricting member. A guide member includes a guide hole for insertion of a rod portion of the upper-blade drive member and is fixed to the base. The upper-blade drive member is inserted through a guide member of the base and moved by a connecting rod. The lower-blade positioning device includes a lower-blade holder, an adjustment member. A lower-blade shaft has one end fixed to the base and another end extended out of the base, rotating the adjustment member can adjust the position of the lower-blade holder.

Abstract: A positioning structure for a movable tongue seat includes: an eccentric positioning member disposed between the movable tongue seat and the cutter seat, the eccentric positioning member is provided with a rotary end which is located toward one end of the cutter seat, wherein the eccentric positioning member rotates about the rotary end and is further provided with a drive end which is inserted in a slot of the movable tongue seat, the drive end and the rotary end are not coaxially aligned; and a pivot hole and a pivot provided between the movable tongue seat and the cutter seat, so that the movable tongue seat is able rotate on the cutter seat by rotating about the pivot. When the eccentric positioning member rotates about the rotary end, the drive end can push the movable tongue seat to rotate about the pivot to a desired position.

Abstract: A sewing machine with a threading and air supply selecting device includes a base with a main shaft for driving at least one thread wiper, and a guiding pipe is provided on the thread wiper. On the base is further disposed an air supply device driven by a drive force source. Between the air supply source and he guiding pipe is disposed a pipe-moving device for moving the connecting pipe to the guiding pipe. A swing arm of a connecting rod assembly serves to control ON and Off of the air supply source. A directional positioning device is used to stop the main shaft from rotation, when the air supply source is working.

Abstract: A differential feeding mechanism for a sewing machine employs a differential mechanism to move first and second toothed bars. The differential mechanism includes a first link member to drive a first toothed bar, a second link member, and a third link member to drive a second toothed bar. The third link member is provided with an adjustment groove, in which being slidably disposed a slide member which can be adjusted in position with respect to the third link member. Adjusting the position of the slide member can change the fulcrum of the third link member and the swing amplitude of the two ends of the third link member, which consequently adjusts the differential feed of the first and second toothed bars.

Abstract: A cutting device for a sewing machine includes an upper-blade positioning device and a lower-blade positioning device. The upper-blade positioning device includes an upper blade upper blade fixed at a head portion of the upper-blade holder, and a spring and a restricting member sleeved on a body portion of the upper-blade holder. A restricting pin is engaged between an upper-blade drive member and the restricting member. A guide member includes a guide hole for insertion of a rod portion of the upper-blade drive member and is fixed to the base. The upper-blade drive member is inserted through a guide member of the base and moved by a connecting rod. The lower-blade positioning device includes a lower-blade holder, an adjustment member. A lower-blade shaft has one end fixed to the base and another end extended out of the base, rotating the adjustment member can adjust the position of the lower-blade holder.

Abstract: A differential feeding mechanism for a sewing machine employs a differential mechanism to move first and second toothed bars. The differential mechanism includes a first link member to drive a first toothed bar, a second link member, and a third link member to drive a second toothed bar. The third link member is provided with an adjustment groove, in which being slidably disposed a slide member which can be adjusted in position with respect to the third link member. Adjusting the position of the slide member can change the fulcrum of the third link member and the swing amplitude of the two ends of the third link member, which consequently adjusts the differential feed of the first and second toothed bars.

Abstract: A cutting device for a sewing machine includes an upper-blade positioning device and a lower-blade positioning device. The upper-blade positioning device includes an upper blade upper blade fixed at a head portion of the upper-blade holder, and a spring and a restricting member sleeved on a body portion of the upper-blade holder. A restricting pin is engaged between an upper-blade drive member and the restricting member. A guide member includes a guide hole for insertion of a rod portion of the upper-blade drive member and is fixed to the base. The upper-blade drive member is inserted through a guide member of the base and moved by a connecting rod. The lower-blade positioning device includes a lower-blade holder, an adjustment member. A lower-blade shaft has one end fixed to the base and another end extended out of the base, rotating the adjustment member can adjust the position of the lower-blade holder.

Abstract: A guiding structure for a cloth feeding mechanism which is disposed on a base below a needle plate of a sewing machine, a feeding dog driven by the cloth feeding mechanism is mounted on a mounting seat. The guiding structure comprising a first guiding portion formed on the mounting seat and a second guiding portion formed on a guiding device, the first and second guiding portions cooperate with each other to guide the feeding dog to move in the X-axis direction, so that the cloth can be fed precisely along the predetermined path to ensure good sewing quality.