CN112048836B

CN112048836B - a sewing machine

Info

Publication number: CN112048836B
Application number: CN201910486758.3A
Authority: CN
Inventors: 管建平; 吴善敏; 洪志敏; 林晓晓
Original assignee: Jack Technology Co Ltd
Current assignee: Jack Technology Co Ltd
Priority date: 2019-06-05
Filing date: 2019-06-05
Publication date: 2022-03-15
Anticipated expiration: 2039-06-05
Also published as: CN112048836A

Abstract

The invention provides a sewing machine, comprising a feeding dog, a presser foot, a feeding mechanism, a presser foot lifting mechanism, a driving source, a driving crank driven and rotated by the driving source, a feeding driving connecting rod, a lifting and pressing driving plate, and The transmission part of the plate, one end of the feeding driving connecting rod is hinged to the driving crank, and the other end is connected to the feeding mechanism; the transmission part is in contact with the outer peripheral surface of the driving crank; During the rotation of the crank, when the transmission member is in contact with the equal-diameter arc surface segment on the outer circumference of the driving crank, the driving crank changes the feeding range of the feeding mechanism through the feeding driving connecting rod; when the transmission member and the variable diameter arc on the outer circumference of the driving crank When the face segments are in contact with each other, the driving crank drives the presser foot to lift up through the transmission element, the tooth-lifting driving plate and the presser-foot-lifting mechanism. The overall structure of the present application is simpler and more compact, the number of parts used is small, the structure of each part is simplified, and the processing difficulty of each part is reduced.

Description

Sewing machine

Technical Field

The present invention relates to a sewing machine.

Background

Sewing machines are of the flat-bed, over-lock, flat-bed or the like type, which use one or more sewing threads to form one or more stitches in the material to be sewn, so as to interweave or sew up one or more layers of material to be sewn. At present, an automatic backstitch mechanism, an automatic seam-thickening mechanism and an automatic presser foot lifting mechanism are arranged in a computer lockstitch sewing machine, and all the mechanisms are driven by electromagnets to realize the function of automatic control. However, the existing sewing machine has the following defects due to the adoption of electromagnet drive: 1. when the electromagnet drives the automatic backstitch mechanism, the regulator is required to swing to impact the stud so as to change the needle pitch, but noise is generated when the regulator and the stud impact, so that the use experience of a user is influenced; 2. the automatic seam-sealing mechanism needs an independent electromagnet, and continuous actions such as backstitch, trimming and the like are caused, so that the power supply is insufficient, and the action effect is influenced; 3. after the automatic presser foot lifting mechanism is driven by the electromagnet, the sound of the automatic presser foot lifting mechanism is loud, the customer experience is influenced, and the size of the electromagnet is not large due to space limitation of the existing built-in automatic presser foot lifting mechanism, so that the attraction of the electromagnet is insufficient, the use effect is influenced, and the service life of the electromagnet is also shortened.

Furthermore, in order to solve some defects caused by adopting an electromagnet, some sewing machines adopting a stepping motor to adjust the needle pitch and adopting a stepping motor to lift the presser foot are provided in the market at present, one stepping motor is adopted to control the swing seat to swing through one set of transmission mechanism to realize the needle pitch adjustment, the other stepping motor is adopted to drive the presser foot to lift through the other set of transmission mechanism, and therefore two stepping motors and corresponding control devices are arranged in one sewing machine, so that the cost is higher, the occupied space is larger, the heating is larger, and the technology is difficult to popularize in a large amount.

Further, the chinese patent application No. 201510515041.9 discloses a lockstitch sewing machine, which uses a stepping motor to realize two functions of needle pitch adjustment and automatic presser foot lifting, and has a cam driven by the stepping motor to rotate reciprocally, a stepping pressure lifting crank acting on a pressure lever, and a needle pitch adjustment crank acting on a feed shaft, and the cam has a stepping pressure lifting convex part for pushing the stepping pressure lifting crank and a needle pitch adjustment convex part for pushing the needle pitch adjustment crank. Therefore, the cam arranged in the flat sewing machine is provided with two functional convex parts which are arranged along the axial direction of the cam in a staggered mode, and the processing difficulty is high.

Disclosure of Invention

In view of the above-mentioned drawbacks of the prior art, an object of the present invention is to provide a sewing machine that uses one driving source to simultaneously achieve the stitch length adjustment and the automatic presser foot lifting, and to reduce the difficulty in processing each component.

In order to achieve the above object, the present invention provides a sewing machine, comprising a feeding tooth, a presser foot, a feeding mechanism for driving the feeding tooth to reciprocate back and forth, a presser foot lifting mechanism for driving the presser foot to lift upwards, a driving source, a driving crank driven to rotate by the driving source, a feeding driving link, a pressure lifting driving plate with a first fixed swing fulcrum, and a transmission member mounted at one end of the pressure lifting driving plate, the periphery of the driving crank is provided with an equal-diameter arc surface section which is concentric with the rotation center of the driving crank and a variable-diameter arc surface section which is eccentric from the rotation center of the driving crank, the equal-diameter arc surface section and the variable-diameter arc surface section are positioned on the same circumferential surface of the driving crank, one end of the feeding driving connecting rod is hinged with the driving crank, the other end of the feeding driving connecting rod is connected with the feeding mechanism, the transmission part is in contact fit with the outer peripheral surface of the driving crank, and the other end of the pressure lifting driving plate is connected with the pressure lifting foot mechanism;

when the driving crank is rotated by the driving source, the driving crank changes the feeding amplitude of the feeding mechanism through the feeding driving connecting rod when the driving piece is abutted to the equal-diameter arc surface section on the periphery of the driving crank; when the transmission piece is abutted against the variable-diameter arc surface section on the periphery of the driving crank, the driving crank drives the presser foot to be lifted upwards through the transmission piece, the tooth lifting driving plate and the presser foot lifting mechanism.

Further, the driving source is a motor fixed to a housing of the sewing machine, and the driving crank is fixed to an output shaft of the motor.

Furthermore, one end of the equal-diameter arc surface section is connected with one end of the variable-diameter arc surface section.

Further, the sewing machine has a maximum positive thread pitch, a zero thread pitch, and a minimum negative thread pitch in a process in which the driving crank changes the feeding amplitude of the feeding mechanism through the feeding driving link.

Further, the feeding mechanism comprises a feeding cam fixed on a main shaft of the sewing machine, a feeding connecting rod, a swing seat with a second fixed swing fulcrum, a first connecting rod, a second connecting rod, a feeding shaft parallel to the main shaft, a feeding crank fixed on the feeding shaft and a transmission assembly connected between the feeding shaft and the feeding teeth, the upper end of the feeding connecting rod is rotatably sleeved on the periphery of the feeding cam, the lower end of the feeding connecting rod, one end of the first connecting rod and one end of the second connecting rod are coaxially hinged, the other end of the first connecting rod is hinged with the swing seat, the other end of the second connecting rod is hinged with the feeding crank, and the other end of the feeding driving connecting rod is hinged to the swing seat.

Further, both sides of the swing seat are provided with support pins parallel to the feeding shaft, the support pins are fixed to the sewing machine housing, the swing seat is rotatably mounted on the support pins, and the support pins constitute a second fixed swing fulcrum of the swing seat.

Further, still including restoring to the throne board and drive extension spring, the board that restores to the throne is fixed in the sewing machine casing, the both ends of drive extension spring link to each other with the board that restores to the throne and swing seat respectively, pay-off drive connecting rod makes swing seat pivoted direction opposite with drive extension spring messenger swing seat pivoted direction.

Furthermore, a limiting block is fixed on the swing seat, the feeding driving connecting rod is hinged with the swing seat through a connecting pin, the other end of the feeding driving connecting rod is provided with a sliding groove extending along the length direction of the feeding driving connecting rod, the connecting pin is arranged in the sliding groove in a penetrating manner, and the limiting block is used for abutting against a sewing part of the sewing machine, the position of which is kept unchanged; when the limiting block is not abutted to the sewing component, the connecting pin is abutted to the groove bottom of the sliding groove; in the process that the presser foot is lifted upwards, the limiting block can be abutted against the sewing component, and after the limiting block is abutted against the sewing component, the current needle pitch of the sewing machine is larger than or equal to the maximum positive needle pitch of the sewing machine.

Further, the presser foot lifting mechanism comprises a pressure lifting connecting rod, a right lever with a third fixed swing fulcrum, a pressure lifting pull rod, a left lever with a fourth fixed swing fulcrum, a pressure lifting plate, a pressure lever guide frame and a pressure lever, wherein two ends of the pressure lifting connecting rod are respectively hinged with the other end of the pressure lifting driving plate and one end of the right lever, two ends of the pressure lifting pull rod are respectively hinged with the other end of the right lever and one end of the left lever, the other end of the left lever is hinged with the upper end of the pressure lifting plate, a lifting hook part is arranged on the pressure lifting plate, a connecting protruding part clamped with the lifting hook part is arranged on the pressure lever guide frame, the pressure lever guide frame is fixed at the upper end of the pressure lever, and the presser foot is installed at the lower end of the pressure lever.

As described above, the sewing machine according to the present invention has the following advantageous effects:

the needle pitch adjusting and automatic presser foot lifting function can be realized by adopting one driving source (such as a motor), particularly, the equal-diameter arc surface section and the variable-diameter arc surface section on the driving crank are positioned on the same peripheral surface, and the processing difficulty of the driving crank can be greatly reduced; compared with the prior art, the structure of the device is simpler and more compact, the number of used parts is small, the structure of each part is simplified, and the processing difficulty of each part is reduced, so that the device is easier to realize; meanwhile, the crank connecting rod transmission is adopted, and the transmission efficiency is higher compared with that of cam transmission.

Drawings

Fig. 1 is a schematic view of a sewing machine according to the present application.

Fig. 2 and 3 are schematic structural diagrams of fig. 1 from different perspectives with the chassis omitted.

Fig. 4 is an enlarged view of a circle a of fig. 3.

Fig. 5 is an enlarged view of circle B of fig. 3.

Fig. 6 is a schematic view of the structure of the driving crank in the present application.

FIG. 7 is a schematic view of the minimum negative gauge condition of the sewing machine of the present application.

FIG. 8 is a schematic view of the present application showing a sewing machine in a zero gauge condition.

FIG. 9 is a schematic view of the sewing machine of the present application in a maximum positive gauge condition.

Fig. 10 is a schematic structural view of the sewing machine in the present application when the current needle gauge is slightly larger than the maximum positive needle gauge in the process of lifting the presser foot.

Fig. 11 is a schematic structural view of the sewing machine in the present application in a state where the presser foot is raised.

Fig. 12 is a schematic structural diagram of fig. 11 from another view angle.

Description of the element reference numerals

1 pressure foot

2 driving source

3 drive crank

31 equal diameter arc surface section

32 variable diameter arc surface section

4 feeding driving connecting rod

41 chute

5 lift and press drive plate

6 driving medium

7 casing

8 feeding cam

9 feeding connecting rod

10 swing seat

11 first link

12 second connecting rod

13 feeding shaft

14 feeding crank

15 supporting pin

16 reset plate

17 drive tension spring

18 stopper

19 connecting pin

20 lifting and pressing connecting rod

21 Right lever

22 lifting and pressing pull rod

23 left lever

24 lifting and pressing lifting plate

241 lifting hook

25 pressure bar guide frame

251 connection protrusion

26 pressure lever

Detailed Description

The following description of the embodiments of the present invention is provided for illustrative purposes, and other advantages and effects of the present invention will become apparent to those skilled in the art from the present disclosure.

It should be understood that the structures, proportions, and dimensions shown in the drawings and described herein are for illustrative purposes only and are not intended to limit the scope of the present invention, which is defined by the claims, but rather by the claims. In addition, the terms such as "upper", "lower", "left", "right", "middle" and "one" used in the present specification are for convenience of description only and are not intended to limit the scope of the present invention, and changes or modifications of the relative relationship thereof may be made without substantial technical changes and modifications.

The present application provides a sewing machine having a housing 7, a main shaft rotatably mounted in the housing 7, and a main motor for driving the main shaft to rotate. For convenience of description, the axial direction of the main shaft is defined as a left-right direction, the direction of the main shaft towards the head of the sewing machine is a left direction, and the direction of the main shaft towards the tail of the sewing machine is a right direction; defining the feeding direction of the feeding mechanism as the front direction when the sewing machine sews normally; directions both orthogonal to the left-right direction and the front-rear direction are defined as up-down directions.

As shown in fig. 1 to 3, the sewing machine according to the present application includes a feed dog, a presser foot 1, a feed mechanism for driving the feed dog to reciprocate back and forth, a presser foot lifting mechanism for driving the presser foot 1 to lift upward, a drive source 2, a drive crank 3 driven to rotate by the drive source 2, a feed drive link 4, a pressure lifting drive plate 5 having a first fixed swing fulcrum O1, and a transmission member 6 mounted at the rear end of the pressure lifting drive plate 5; as shown in fig. 6, the periphery of the driving crank 3 has a section of arc surface, the section of arc surface includes an equal-diameter arc surface section 31 concentric with the rotation center of the driving crank 3 and a variable-diameter arc surface section 32 eccentric from the rotation center of the driving crank 3, the equal-diameter arc surface section 31 and the variable-diameter arc surface section 32 are located on the same peripheral surface of the driving crank 3; the upper end of the feeding driving connecting rod 4 is hinged to the driving crank 3, and the lower end of the feeding driving connecting rod 4 is connected with the feeding mechanism and acts on the feeding mechanism; the transmission piece 6 is in contact fit with the outer peripheral surface of the driving crank 3, and the front end of the pressure lifting driving plate 5 is connected with the pressure lifting pin mechanism. The first fixed swing fulcrum O1 of the pressure raising drive plate 5 is located between the front end and the rear end of the pressure raising drive plate 5 in the following manner: a first axial screw extending in the left-right direction is fixed to the sewing machine housing 7, and the pressure raising/lowering drive plate 5 is attached to the first axial screw and is rotatable around the first axial screw, and the first axial screw constitutes a first fixed swing fulcrum O1 of the pressure raising/lowering drive plate 5.

In the sewing machine related to the application, in the process that the driving source 2 rotates the driving crank 3, when the transmission piece 6 is abutted to the equal-diameter arc surface section 31 on the periphery of the driving crank 3, the driving crank 3 changes the feeding amplitude of the feeding mechanism through the feeding driving connecting rod 4 to realize the adjustment of the needle pitch, but the equal-diameter arc surface section 31 on the driving crank 3 does not push the transmission piece 6, so the pressure lifting driving plate 5 does not rotate, the pressure lifting foot mechanism does not act, and the pressure foot 1 is not lifted; when the transmission piece 6 is abutted against the variable diameter arc surface section 32 on the periphery of the driving crank 3, the variable diameter arc surface section 32 on the driving crank 3 pushes the transmission piece 6, so that the pressure lifting driving plate 5 rotates around the first fixed swing fulcrum O1, and the pressure lifting pin mechanism is driven to act, and therefore the driving crank 3 drives the pressure pin 1 to be lifted upwards through the transmission piece 6, the tooth lifting driving plate and the pressure lifting pin mechanism. Therefore, the needle pitch adjustment and the automatic presser foot lifting function can be realized simultaneously by adopting one driving source 2 such as a motor, and particularly, the equal-diameter arc surface section 31 and the variable-diameter arc surface section 32 on the driving crank 3 are positioned on the same peripheral surface, so that the processing difficulty of the driving crank 3 can be greatly reduced; compared with the prior art, the structure of the device is simpler and more compact, the number of used parts is small, the structure of each part is simplified, and the processing difficulty of each part is reduced, so that the device is easier to realize; meanwhile, the crank connecting rod transmission is adopted, and the transmission efficiency is higher compared with that of cam transmission.

In the present application, as shown in fig. 1, the driving source 2 is a motor, preferably a stepping motor, fixed to the sewing machine housing 7, the driving crank 3 is fixed to an output shaft of the motor, and the motor directly drives the driving crank 3 to rotate; the hinge point of the driving crank 3 and the feeding driving connecting rod 4 is eccentric to the rotation center of the driving crank 3. As shown in fig. 3, the transmission member 6 is a rolling pin mounted on the pressure-raising driving plate 5, and the rolling pin is in rolling fit with the equal-diameter arc surface section 31 and the variable-diameter arc surface section 32 on the driving crank 3; of course, in other embodiments, the transmission member 6 may be integrated with the tooth lifting drive plate, or the transmission member 6 may be a roller, a fixing pin, a bearing, or other structures installed on the lifting drive plate 5.

Further, in the process that the driving crank 3 changes the feeding amplitude of the feeding mechanism through the feeding driving connecting rod 4, the sewing machine has the maximum positive-value needle pitch, the zero needle pitch and the minimum negative-value needle pitch; the sewing machine carries out the closed seam under the condition of zero needle pitch, the sewing machine carries out the backstitch under the condition of minimum negative value needle pitch-zero needle pitch, and the sewing machine carries out the normal sewing under the condition of zero needle pitch-maximum positive value needle pitch. The maximum positive needle pitch and the minimum negative needle pitch are set according to actual requirements, such as: the minimum negative gauge may be-5, -7 and the maximum positive gauge may be 5, 7. In the view shown in fig. 7, the constant diameter arc surface segment 31 and the variable diameter arc surface segment 32 each have a head end and a tail end in the clockwise direction of the driving crank 3, and the tail end of the constant diameter arc surface segment 31 is connected to the head end of the variable diameter arc surface segment 32. In particular, when the transmission member 6 abuts against the head end of the equal-diameter arc surface section 31, as shown in fig. 7, the current stitch length of the sewing machine is the minimum negative stitch length at this time; when the transmission piece 6 abuts against the tail end of the equal-diameter arc surface section 31, as shown in fig. 9, the current stitch length of the sewing machine is the maximum positive stitch length or is slightly larger than the maximum positive stitch length; when the initial head end butt of driving medium 6 and constant diameter arc surface section 31, follow-up when adjusting the gauge needle along with driving source 2 drives drive crank 3 clockwise rotation, sewing machine's current gauge needle can be from minimum negative value gauge needle crescent for 0, again crescent to the maximum positive value gauge needle. When the driving source 2 drives the driving crank 3 to rotate clockwise continuously and the transmission member 6 abuts against the tail end of the variable diameter arc surface section 32, as shown in fig. 11 and 12, the presser foot 1 in the sewing machine is in an upward-lifted state.

The preferable structure of the feeding mechanism is as follows: as shown in fig. 2, 3 and 5, the feeding mechanism includes a feeding cam 8 fixed on a main shaft of the sewing machine, a feeding link 9, a swing seat 10 having a second fixed swing fulcrum O2, a first link 11, a second link 12, a feeding shaft 13 parallel to the main shaft, a feeding crank 14 fixed on the feeding shaft 13, and a transmission assembly connected between the feeding shaft 13 and a feeding tooth, wherein the upper end of the feeding link 9 is rotatably sleeved on the periphery of the feeding cam 8, the lower end of the feeding link 9, the rear end of the first link 11 and the rear end of the second link 12 are coaxially hinged, the front end of the first link 11 is hinged with the swing seat 10, the front end of the second link 12 is hinged with the feeding crank 14, the lower end of the feeding driving link 4 is hinged to the swing seat 10, and the change of the needle pitch of the sewing machine is realized by the rotation of the swing seat 10. When the sewing machine operates, the main shaft drives the feeding crank 14 and the feeding shaft 13 to swing through the feeding cam 8, the feeding connecting rod 9, the first connecting rod 11 and the second connecting rod 12, and the feeding shaft 13 drives the feeding teeth to reciprocate back and forth through the transmission assembly, so that feeding is realized. When the sewing machine stops operating, the driving crank 3 is driven to rotate by the driving source 2, the driving crank 3 drives the swing seat 10 to rotate for an angle around the second fixed swing fulcrum O2 through the feeding driving connecting rod 4, and then the amplitude of the front-back reciprocating motion of the feeding tooth driven by the feeding mechanism when the subsequent sewing machine operates is changed, namely the feeding amplitude is changed, and the needle pitch adjustment is realized. The transmission assembly connected between the feeding shaft 13 and the feeding tooth is prior art, and refer to a sewing machine feed lifting mechanism disclosed in chinese patent application No. 201510640562.7, and therefore, it will not be described herein.

Preferably, the second fixed swing fulcrum O2 of the swing base 10 is formed in a manner that: as shown in fig. 3 and 5, the swing base 10 is provided with support pins 15 on both right and left sides thereof in parallel with the feed shaft 13, the support pins 15 are fixed to the sewing machine housing 7, the swing base 10 is rotatably mounted on the support pins 15, and the support pins 15 constitute a second fixed swing fulcrum O2 of the swing base 10. In addition, as shown in fig. 2 and fig. 3, the sewing machine further includes a reset plate 16 and a driving tension spring 17, the reset plate 16 is fixed to the sewing machine case 7, both ends of the driving tension spring 17 are respectively connected to the reset plate 16 and the swing base 10, and the direction in which the feeding driving link 4 rotates the swing base 10 is opposite to the direction in which the driving tension spring 17 rotates the swing base 10.

Particularly, in the process that the driving crank 3 drives the pressure lifting driving plate 5 to swing and the pressure lifting is realized through the pressure lifting mechanism, the driving crank 3 simultaneously drives the feeding driving connecting rod 4 to move, and the feeding teeth are driven by the feeding mechanism to move in the front and back directions, the feeding teeth move in tooth grooves of a needle plate in the sewing machine, the length of the tooth grooves in the front and back directions is limited, and if the movement amplitude of the feeding teeth in the front and back directions in the pressure lifting process is large, the feeding teeth collide with the needle plate. To avoid this phenomenon, as shown in fig. 2, 11 and 12, a limit block 18 is fixed on the swing seat 10, and the limit block 18 is used for abutting against a sewing component with a constant position in the sewing machine, in this embodiment, the sewing component is a feeding shaft 13; the feeding driving connecting rod 4 is hinged with the swinging seat 10 through a connecting pin 19 extending leftwards and rightwards, the connecting pin 19 is fixed on the swinging seat 10, the lower end of the feeding driving connecting rod 4 is provided with a sliding groove 41 extending along the length direction of the feeding driving connecting rod 4, and the connecting pin 19 is arranged in the sliding groove 41 in a penetrating mode; when the limiting block 18 is not abutted with the feeding shaft 13, the connecting pin 19 is always abutted with the bottom of the lower end of the sliding chute 41; in the process that the presser foot 1 is lifted upwards, the transmission piece 6 is in contact with the reducing arc surface section 32 on the periphery of the driving crank 3, the driving crank 3 continues to rotate clockwise in the view shown in fig. 7, the driving crank 3 drives the swing seat 10 to swing through the feeding driving connecting rod 4, and the swing seat 10 drives the limiting block 18 to swing together until the limiting block 18 is abutted against the feeding shaft 13; after the limiting block 18 is abutted with the feeding shaft 13, as shown in fig. 10, the current needle pitch of the sewing machine is slightly larger than or equal to the maximum positive needle pitch of the sewing machine, and then the driving crank 3 continuously rotates clockwise in the view shown in fig. 7 along with the driving crank 3, the driving crank 3 drives the presser foot 1 to be lifted upwards through the driving part 6, the pressure lifting driving plate 5 and the pressure lifting foot mechanism, however, the abutting of the limiting block 18 and the feeding shaft 13 limits the swinging of the limiting block 18 and the swinging seat 10, so that the feeding mechanism does not act, the movement of the feeding tooth is limited, and the collision of the feeding tooth and a needle plate is effectively avoided; meanwhile, the groove bottom of the lower end of the chute 41 is disengaged from the connecting pin 19, and the feed drive link 4 moves in the extending direction of the chute 41 relative to the connecting pin 19. In other embodiments, the stop 18 may abut against any contactable, but positionally invariant sewing component of the sewing machine other than the feed shaft 13.

The preferable structure of the presser foot lifting mechanism is as follows: as shown in fig. 2 to 4, the presser foot lifting mechanism includes a presser link 20, a right lever 21 having a third fixed swing fulcrum O3, a presser pull rod 22, a left lever 23 having a fourth fixed swing fulcrum O4, a presser lifting plate 24, a presser bar guide 25, and a presser bar 26 extending up and down; the front end of the pressure lifting driving plate 5 is hinged with the lower end of a pressure lifting connecting rod 20, the upper end of the pressure lifting connecting rod 20 is hinged with the right lower end of a right lever 21, the left upper end of the right lever 21 is hinged with the right end of a pressure lifting pull rod 22, the left end of the pressure lifting pull rod 22 is hinged with the upper end of a left lever 23, the left lower end of the left lever 23 is hinged with the upper end of a pressure lifting plate 24, a lifting hook portion 241 is arranged on the pressure lifting plate 24, a connecting protruding portion 251 clamped with the lifting hook portion 241 is arranged on a pressure lever guide frame 25, the pressure lever guide frame 25 is fixed at the upper end of a pressure lever 26, and the pressure foot 1 is installed at the lower end of the pressure lever 26. The rotation of the pressure lifting driving plate 5 is transmitted to the pressure foot 1 through the pressure foot lifting mechanism, and the pressure foot 1 can be driven to lift. Preferably, the right lever 21 is substantially L-shaped, and the third fixed swing fulcrum O3 is located between the right lower end and the left upper end of the right lever 21, and is formed by: a second axial screw extending in the front-rear direction is fixed to the sewing machine housing 7, and the right lever 21 is attached to the second axial screw and rotatable about the second axial screw, which constitutes a third fixed swing fulcrum O3 of the right lever 21. Similarly, the fourth fixed swing fulcrum O4 of the left lever 23 is formed in the following manner: a third axial screw extending forward and backward is fixed to the sewing machine housing 7, and a right lower end of the left lever 23 is attached to the third axial screw and is rotatable around the third axial screw, which constitutes a fourth fixed swing fulcrum O4 of the left lever 23.

The sewing machine with the structure has the following working principle:

needle pitch adjustment: in the view shown in fig. 7, the sewing machine is in a state of a minimum negative gauge, and at this time, the sewing machine can perform backstitch with a set maximum gauge, and the driving member 6 abuts against the front end of the constant diameter arc surface section 31. When the needle pitch is adjusted, the driving source 2 makes the driving crank 3 rotate clockwise, the feeding driving connecting rod 4 descends, and the driving tension spring 17 drives the swinging seat 10 to rotate counterclockwise, so as to reduce the feeding amplitude of the feeding mechanism, namely, reduce the needle pitch in the backstitch state and increase the needle pitch value of the current needle pitch of the sewing machine, for example: the stitch length value of the current stitch length of the sewing machine is increased from-7 to-4. When the stitch length value of the current stitch length of the sewing machine is increased to 0, the sewing machine is in a zero stitch length state, as shown in fig. 8, and the sewing machine can perform an encrypted seam. Then, the driving source 2 makes the driving crank 3 continue to rotate clockwise, the driving tension spring 17 makes the swing seat 10 continue to rotate counterclockwise, the current needle pitch of the sewing machine increases from 0 to a positive value, the feeding amplitude of the feeding mechanism increases, that is, the needle pitch under the normal sewing state is increased, and the needle pitch value of the current needle pitch of the sewing machine is increased, for example: the stitch length value of the current stitch length of the sewing machine is increased from 1 to 4. When the tension spring 17 is driven to rotate the swing seat 10 counterclockwise to the position shown in fig. 9, the sewing machine is in the state of the maximum positive gauge. On the contrary, when the driving source 2 rotates the driving crank 3 counterclockwise, the feeding driving link 4 pulls the connecting pin 19 through the contact between the bottom of the chute 41 and the connecting pin 19, so as to drive the swing seat 10 to rotate clockwise, and further the current needle pitch of the sewing machine is reduced from a positive value to 0 for performing a dense sewing or reduced to a negative value for performing a backstitch. Stitch length value for the stitch length of the sewing machine: the range of 0-positive value corresponds to normal sewing of the sewing machine, and the larger the value is, the larger the needle distance is in normal sewing; 0 corresponds to the encrypted seam of the sewing machine; the range of 0-negative value corresponds to backstitch of the sewing machine, and the smaller the value, the larger the backstitch needle pitch. In the above needle pitch adjusting range, the transmission member 6 is always in contact with the equal-diameter arc surface section 31 on the driving crank 3, so the transmission member 6 is not pushed, and the rotation of the driving crank 3 does not affect the positions of the pressure lifting driving plate 5 and the pressure foot 1.

Automatically lifting a presser foot: when sewing stops, when needing to lift the presser foot, the driving source 2 makes the driving crank 3 rotate clockwise from the position of the needle gauge value of locating at present, swing seat 10 anticlockwise rotates, stopper 18 on the swing seat 10 swings to the direction of being close to the pay-off axle 13, through the position of the maximum positive value needle gauge that the sewing machine set for, until stopper 18 butt to pay-off axle 13 on, as shown in figure 10, the present needle gauge of sewing machine is slightly greater than maximum positive value needle gauge this moment, make stopper 18 can not influence the normal sewing process of sewing machine, in order to reduce the requirement to stopper 18 size, installation accuracy. Then, as the driving crank 3 continues to rotate clockwise, the bottom of the lower end of the upper chute 41 of the feeding driving connecting rod 4 is separated from the connecting pin 19, the variable diameter arc surface section 32 on the driving crank 3 enables the pressure raising driving plate 5 to rotate by pushing the driving part 6, and the pressure foot 1 is driven to be raised upwards by the pressure foot raising mechanism, as shown in fig. 11 and 12; in the process, the sliding groove 41 on the feeding driving connecting rod 4 slides along the connecting pin 19, and the position of the swinging seat 10 is not influenced. After the presser foot 1 is lifted up to complete corresponding operation, the presser foot 1 is put down, the driving source 2 enables the driving crank 3 to rotate anticlockwise and reset to the position before the presser foot is lifted, all parts in the presser foot lifting mechanism reset under the action of the pressing reset power, the feeding driving connecting rod 4 resets, and the swinging seat 10 resets under the action of the driving tension spring 17.

In summary, the sewing machine related to the present application has the following beneficial effects:

1. by controlling the rotation of the motor constituting the driving source 2, the needle pitch adjustment, the dense sewing, the normal sewing and the backstitch can be performed, and no impact is generated in the adjustment process; in the same way, in the presser foot lifting process, the presser foot lifting is realized by the rolling fit between the reducing arc surface on the driving crank 3 and the transmission part 6, and no impact is generated, so that the problems of backstitch, needle pitch adjustment and noise in the presser foot lifting process can be avoided.

2. The needle pitch adjustment and the automatic presser foot lifting function can be realized simultaneously by adopting one motor, the cost can be effectively reduced, and the occupied space can be reduced.

3. Compared with cam transmission, the crank connecting rod transmission has higher transmission efficiency, the mechanism and part precision can be realized more easily, and the processing difficulty of each part is reduced.

Therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value.

The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.

Claims

1. The utility model provides a sewing machine, includes feeding tooth, presser foot (1), the drive feeding tooth reciprocating motion's feeding mechanism and drive presser foot (1) lift presser foot mechanism that upwards lifts up which characterized in that: also comprises a driving source (2), a driving crank (3) driven by the driving source (2) to rotate, a feeding driving connecting rod (4), a pressure lifting driving plate (5) with a first fixed swing fulcrum O1, and a transmission piece (6) arranged at one end of the pressure lifting driving plate (5), the periphery of the driving crank (3) is provided with an equal-diameter arc surface section (31) which is concentric with the rotation center of the driving crank (3) and a variable-diameter arc surface section (32) which is eccentric from the rotation center of the driving crank (3), the equal-diameter arc surface section (31) and the variable-diameter arc surface section (32) are positioned on the same peripheral surface of the driving crank (3), one end of the feeding driving connecting rod (4) is hinged with the driving crank (3), the other end is connected with the feeding mechanism, the transmission piece (6) is in contact fit with the outer peripheral surface of the driving crank (3), and the other end of the pressure lifting driving plate (5) is connected with a pressure lifting pin mechanism;

the feeding mechanism comprises a feeding cam (8) fixed on a main shaft of the sewing machine, a feeding connecting rod (9), a swinging seat (10) with a second fixed swinging fulcrum O2, a first connecting rod (11), a second connecting rod (12), a feeding shaft (13) parallel to the main shaft, a feeding crank (14) fixed on the feeding shaft (13), and a transmission component connected between the feeding shaft (13) and a feeding tooth, the upper end of the feeding connecting rod (9) is rotatably sleeved on the periphery of the feeding cam (8), the lower end of the feeding connecting rod (9), one end of the first connecting rod (11) and one end of the second connecting rod (12) are coaxially hinged, the other end of the first connecting rod (11) is hinged with the swinging seat (10), the other end of the second connecting rod (12) is hinged with the feeding crank (14), the other end of the feeding driving connecting rod (4) is hinged to the swinging seat (10);

in the process that the driving crank (3) is rotated by the driving source (2), when the transmission piece (6) is abutted against the equal-diameter arc surface section (31) on the periphery of the driving crank (3), the driving crank (3) changes the feeding amplitude of the feeding mechanism through the feeding driving connecting rod (4); when the transmission piece (6) is abutted against the reducing arc surface section (32) on the periphery of the driving crank (3), the driving crank (3) drives the presser foot (1) to be lifted upwards through the transmission piece (6), the tooth lifting driving plate and the presser foot lifting mechanism.

2. The sewing machine of claim 1, wherein: the driving source (2) is a motor fixed on a sewing machine shell (7), and the driving crank (3) is fixed on an output shaft of the motor.

3. The sewing machine of claim 1, wherein: one end of the equal-diameter arc surface section (31) is connected with one end of the variable-diameter arc surface section (32).

4. The sewing machine of claim 1, wherein: in the process that the driving crank (3) changes the feeding amplitude of the feeding mechanism through the feeding driving connecting rod (4), the sewing machine has the maximum positive-value needle pitch, the zero needle pitch and the minimum negative-value needle pitch.

5. The sewing machine of claim 1, wherein: two sides of the swing seat (10) are provided with support pins (15) parallel to the feeding shaft (13), the support pins (15) are fixed on the sewing machine shell (7), the swing seat (10) is rotatably arranged on the support pins (15), and the support pins (15) form a second fixed swing fulcrum O2 of the swing seat (10).

6. The sewing machine of claim 1, wherein: still including restoring to the throne board (16) and drive extension spring (17), it is fixed in sewing machine casing (7) to restore to the throne board (16), the both ends of drive extension spring (17) link to each other with restoring to the throne board (16) and swing seat (10) respectively, pay-off drive connecting rod (4) make swing seat (10) pivoted direction opposite with drive extension spring (17) messenger swing seat (10) pivoted direction.

7. The sewing machine of claim 1, wherein: a limiting block (18) is fixed on the swinging seat (10), the feeding driving connecting rod (4) is hinged with the swinging seat (10) through a connecting pin (19), a sliding groove (41) extending along the length direction of the feeding driving connecting rod (4) is formed in the other end of the feeding driving connecting rod (4), the connecting pin (19) is arranged in the sliding groove (41) in a penetrating mode, and the limiting block (18) is used for being abutted to a sewing part of the sewing machine, wherein the position of the sewing part is not changed; when the limiting block (18) is not abutted to the sewing component, the connecting pin (19) is abutted to the groove bottom of the sliding groove (41); in the process that the presser foot (1) is lifted upwards, the limiting block (18) can be abutted against the sewing component, and after the limiting block (18) is abutted against the sewing component, the current needle pitch of the sewing machine is larger than or equal to the maximum positive needle pitch of the sewing machine.

8. The sewing machine of claim 1, wherein: the pressure foot lifting mechanism comprises a pressure lifting connecting rod (20), a right lever (21) with a third fixed swing fulcrum O3, a pressure lifting pull rod (22), a left lever (23) with a fourth fixed swing fulcrum O4, a pressure lifting plate (24), a pressure lever guide frame (25) and a pressure lever (26), wherein two ends of the pressure lifting connecting rod (20) are respectively hinged with the other end of the pressure lifting driving plate (5) and one end of the right lever (21), two ends of the pressure lifting pull rod (22) are respectively hinged with the other end of the right lever (21) and one end of the left lever (23), the other end of the left lever (23) is hinged with the upper end of the pressure lifting plate (24), a lifting hook part (241) is arranged on the pressure lifting plate (24), a connecting part (251) clamped with the lifting hook part (241) is arranged on the pressure lever guide frame (25), and the pressure lever guide frame (25) is fixed at the upper end of the pressure lever (26), the pressure foot (1) is arranged at the lower end of the pressure rod (26).