Presser foot lifting mechanism of a sewing machine

Abstract

The present application provides a presser foot lifting mechanism for a sewing machine, specifically relating to the technical field of sewing machine manufacturing. It includes a feed dog. It is characterized in that the presser foot lifting mechanism performs the presser foot lifting action in a stationary state before and after the feed dog stops the feeding action. The presser foot lifting mechanism also has a drive presser foot cam, a rotating lever, a presser foot ejector rod, a drive motor and a stitch pitch positioning wheel. When the presser foot ejector rod abuts against the highest point of the presser foot of the drive presser foot cam driven by the drive motor, the sliding member of the rotating lever is located in the middle of the stitch pitch positioning groove of the stitch pitch positioning wheel. The stationary state before and after the feed dog stops the feeding action in the present application is controlled based on the sewing machine's electronic control system, solving the technical problem that the feed dog has a lifting action and rises above the needle plate surface during the presser foot lifting action under the technology of one stepping motor driving two, and has high popularization and application value.

Description

Technical Field

[0001] The present application provides a presser foot lifting mechanism for a sewing machine, specifically relating to the technical field of sewing machine manufacturing. Background Art

[0002] There is a technical solution for a sewing machine that uses a stepping motor to control the stitch length adjustment and the presser foot lifting action. Mechanical transmission components such as a stitch length adjustment crank and a presser foot lifting crank are installed on the motor. The stitch length adjustment crank indirectly or directly acts on the swing seat, and by adjusting the acting angle and position between the stepping motor and the stitch length adjustment crank, the stitch length of the sewing machine is adjusted. Then, the presser foot lifting action is implemented at different rotation angles of the stepping motor, achieving the technical effect of one stepping motor driving two functions. However, during the process of the sewing machine ending the presser foot lifting action, the feed dog connected to the swing seat and the feed shaft will make a raising action, which almost occurs simultaneously with the presser foot lifting action, resulting in the situation that the feed dog is raised above the needle plate surface. The feed dog above the needle plate surface will, firstly, affect the unloading work of the sewn fabric at the end of sewing, and the fabric may be hooked by the feed dog and damaged; secondly, it will have an adverse impact on the operation of the next sewing work. Summary of the Invention

[0003] Aiming at the technical problem that the feed dog makes a lifting action during the presser foot lifting action, the present application provides a presser foot lifting mechanism for a sewing machine, including a feed dog, characterized in that the presser foot lifting mechanism performs the presser foot lifting action in a stationary state before and after the feed dog stops the feeding action.

[0004] Further preferably, the presser foot lifting mechanism further has a drive presser foot cam, a rotating lever, a presser foot lifting rod, a drive motor, and a stitch length positioning wheel. When the presser foot lifting rod abuts against the highest point of the presser foot of the drive presser foot cam driven by the drive motor, the sliding member of the rotating lever is located in the middle of the stitch length positioning groove of the stitch length positioning wheel, and the presser foot lifting mechanism performs the presser foot lifting action in a stationary state before and after the feed dog stops the feeding action.

[0005] Preferably, the sliding member enters the stitch length positioning groove from the first return groove or the second return groove of the stitch length positioning wheel and pushes the stitch length positioning groove, and the sliding member indirectly pushes the swing seat.

[0006] Preferably, either the first presser foot acting surface or the second presser foot acting surface of the presser foot cam can reach the highest point of the presser foot for the presser foot lifting rod, and the presser foot lifting rod returns to the starting position from the first return groove or the second return groove.

[0007] Preferably, the presser foot lifting rod is sleeved in a positioning sleeve that the presser foot lifting mechanism further has. The presser foot lifting rod hinges the presser foot lever, and the presser foot lever is connected to the end execution part of the presser foot, and then the end execution part of the presser foot performs the presser foot lifting action.

[0008] Preferably, the first return groove or the second return groove is used for the slider to return to the stitch pitch positioning groove at the maximum positive stitch pitch point or the maximum negative stitch pitch point of the swing seat, and the maximum positive stitch pitch point and the maximum negative stitch pitch point are located at the end points of the stitch pitch adjustment groove.

[0009] Preferably, the stitch pitch positioning groove has an outer circular wall and an inner circular wall, and the slider slides between the outer circular wall and the inner circular wall.

[0010] Preferably, the output shaft of the driving motor is installed with a stitch pitch positioning wheel, and the output shaft and the arc of the stitch pitch positioning groove are on the same concentric arc.

[0011] Preferably, the driving motor performs the presser foot lifting action within the presser foot lifting angle of the sewing machine.

[0012] The presser foot lifting mechanism proposed in this application performs the presser foot lifting action in the static state before and after the feed dog stops the feeding action; when the presser foot lifting rod abuts against the highest point of the presser foot lifting cam driven by the driving motor, the slider of the rotating lever is located in the middle of the stitch pitch positioning groove of the stitch pitch positioning wheel, and the presser foot lifting mechanism of the sewing machine also performs the presser foot lifting action. The static state before and after the feed dog stops the feeding action in this application is controlled based on the sewing machine's electronic control system, realizing that the presser foot lifting mechanism of this sewing machine performs the presser foot lifting action in the static state before and after the feed dog stops the feeding action, solving the technical problem that the feed dog lifts and is higher than the needle plate surface during the presser foot lifting action under the technology of one stepping motor driving two, and has high popularization and application value. Description of the Drawings

[0013] Figure 1 is the structural diagram of the presser foot lifting mechanism of a sewing machine in this application;

[0014] Figure 2 is the schematic diagram of the stitch pitch positioning wheel and stitch pitch adjustment of the presser foot lifting mechanism of a sewing machine in this application;

[0015] Figure 3 is the schematic diagram of the stitch pitch adjustment and swing seat of the presser foot lifting mechanism of a sewing machine in this application;

[0016] Figure 4 is the schematic diagram of the stitch pitch adjustment groove of the presser foot lifting mechanism of a sewing machine in this application;

[0017] Figure 5 is the side view of the combined wheel of the presser foot lifting mechanism of a sewing machine in this application;

[0018] Figure 6 is the schematic diagram of the stitch pitch lever of the presser foot lifting mechanism of a sewing machine in this application;

[0019] Figure 7It is a structural diagram of the thread cutting mechanism of the presser foot lifting mechanism of a sewing machine in this application;

[0020] Figure 8 It is a schematic diagram of the presser foot lifting cam of the presser foot lifting mechanism of a sewing machine in this application.

[0021] Reference numerals: drive motor 10, output shaft 11, shaft hole 12, combined wheel 20, stitch pitch positioning wheel 21, stitch pitch adjustment groove 211, stitch pitch positioning groove 212, outer circular wall 21b, inner circular wall 21c, first return groove 213, second return groove 214, maximum positive stitch pitch point 215, maximum negative stitch pitch point 216, presser foot lifting cam 22, first presser foot acting surface 221, second presser foot acting surface 222, highest point of presser foot 223, idle running surface 224, thread cutting crank wheel 23, rotating column 231, swing seat 30, feed swing plate 31, long swing plate 33, short feed swing plate 32, rotating lever 41, sliding member 42, lever support shaft 43, connecting rod 44, machine body 45, feed shaft 51, feed crank 52, swing connecting rod 53, presser foot ejector rod 61, positioning sleeve 62, presser foot lever 63, end executing end of presser foot 64, thread cutting fork wheel 71, fixed shaft 72, thread cutting acting surface 73, thread cutting return acting surface 74, thread cutting connecting rod 75, thread cutting long shaft 76, main shaft motor 81, feed dog 91. Detailed implementation manners

[0022] The following combines the attached Figure 1-8 The preferred embodiments of this application are elaborated in detail so that the advantages and features of this application can be more easily understood by those skilled in the art, thereby making the protection scope of this application more clearly defined. These implementation manners are only used to illustrate the present invention and are not a limitation to the present invention.

[0023] This application proposes a presser foot lifting mechanism for a sewing machine. The sewing machine has a stitch pitch adjustment mechanism, a presser foot lifting mechanism, a thread cutting mechanism, and a drive motor 10. The stitch pitch adjustment mechanism has a stitch pitch positioning wheel 21, a rotating lever 41, and a feed dog 91. An output shaft 11 of the drive motor 10 is provided with a combined wheel 20. The combined wheel 20 is used to realize the stitch pitch adjustment action, the action of positioning the feed dog to stop feeding before and after, the presser foot lifting action, and the thread cutting action of the sewing machine at different time periods. The above four sewing actions are at each driving rotation angle of the drive motor 10. Different functional wheels of the combined wheel 20 complete the four sewing actions, or any one of the four sewing actions, or any combination of two or more sewing actions under the drive of the drive motor 10 within their respective driving rotation angles.

[0024] The above-mentioned combined wheel 20 has three functional wheels, namely the stitch pitch positioning wheel 21, the presser foot lifting cam 22 and the thread cutting crank wheel 23. The above-mentioned stitch pitch positioning wheel 21, presser foot lifting cam 22 and thread cutting crank wheel 23 are combined into a whole to form the combined wheel 20. The three functional wheels can also be separately provided and respectively installed and fixed on the output shaft 11. Whether combined or separately provided, the above-mentioned presser foot lifting cam 22 is located between the stitch pitch positioning wheel 21 and the thread cutting crank wheel 23. In addition, the above-mentioned combined wheel 20 has a shaft hole 12 through which the output shaft 11 can pass for positioning. The combined wheel 20 is sleeved and fixed on the output shaft 11. Therefore, it can be said that the output shaft 11 is equipped with the stitch pitch positioning wheel 21. The arc of the above-mentioned output shaft 11 and the stitch pitch positioning groove 212 are on the same concentric arc.

[0025] The above-mentioned stitch pitch positioning wheel 21 has a stitch pitch adjustment groove 211, a stitch pitch positioning groove 212, a first return groove 213 and a second return groove 214. The two ends of the stitch pitch adjustment groove 211 adjacent to the stitch pitch positioning groove 212 are the first return groove 213 and the second return groove 214 respectively. The stitch pitch adjustment groove 211 corresponds to and matches the rotating lever 41. The working pivot point of the rotating lever 41 is the sliding member 42. The sliding member 42 is located in the middle of the rotating lever 41. The sliding member 42 slides and works between the stitch pitch adjustment groove 211, the stitch pitch positioning groove 212, the first return groove 213 and the second return groove 214 according to the sewing action. The above-mentioned first return groove 213 or the second return groove 214 is used for the sliding member 42 to return to the stitch pitch positioning groove 212 at the maximum positive stitch pitch point 215 or the maximum negative stitch pitch point 216 of the swing seat 30. The maximum positive stitch pitch point 215 and the maximum negative stitch pitch point 216 of the above-mentioned swing seat 30 are at the end points of both ends of the stitch pitch adjustment groove 211. Due to the different models of each sewing machine, the above-mentioned maximum positive stitch pitch point 215 and the maximum negative stitch pitch point 216 are uncertain and can be interchanged. One end of the rotating lever 41 is sleeved on the lever support shaft 43. The lever support shaft 43 is positioned on the machine body 45. The lever support shaft 43 serves as the fixed rotating shaft of the rotating lever 41. The other end of the rotating lever 41 is hinged to the connecting rod 44. The other end of the connecting rod 44 is hinged to the swing seat 30. Stitch pitch adjustment is to drive the motor 10 to rotate the stitch pitch positioning wheel 21 by a certain angle to change the action position of the sliding member 42 in the stitch pitch adjustment groove 211, that is, the stitch pitch adjustment groove 211 pushes the sliding member 42, and then changes the original swing angle of the swing seat 30 through the rotating lever 41 and the connecting rod 44 to achieve stitch pitch adjustment. Stitch pitch adjustment is carried out when the sewing machine is in the stopped state. The adjusted stitch pitch gives the swing seat 30 a new fixed stitch pitch.

[0026] When it is necessary to cut the thread after sewing is completed, under the drive of the drive motor 10 for the stitch pitch positioning wheel 21, the sliding member 42 disengages from the stitch pitch adjustment groove 211 and enters the stitch pitch positioning groove 212 through the first return groove 213 or the second return groove 214. The stitch pitch positioning groove 212 has an outer circular wall 21b and an inner circular wall 21c, and the sliding member 42 slides between the outer circular wall 21b and the inner circular wall 21c. When the sliding member 42 enters the stitch pitch positioning groove 212, it indirectly determines the static state position where the feed dog 91 stops the forward and backward feeding actions. The sewing machine can perform thread cutting in this state where the feeding action stops, achieving the technical effect of almost no remaining thread. When the stitch pitch positioning wheel 21 rotates and the sliding member 42 enters the stitch pitch positioning groove 212 from the stitch pitch adjustment groove 211, the sliding member 42 together with the rotating lever 41 pushes the feed swing plate 31 of the swing seat 30 through the connecting rod 44, causing the long feed swing plate 33 and the short feed swing plate 32 of the swing seat 30 to be pushed into a flush state. In the flush state, the long feed swing plate 33 and the short feed swing plate 32 swing under the drive of the main shaft motor 81, and the swing connecting rod 53 acts on the swing seat 30 with a swing angle of zero, that is, the stitch pitch is zero. The above-mentioned feed crank 52 is fixed on the feed shaft 51 and hinged to the swing seat 30. The feed shaft 51 is indirectly connected to the feed dog 91. When the swing angle of the swing seat 30 is zero, the feed crank 52 connecting the swing seat 30 and the feed shaft 51 does not swing. At this time, the swing seat 30 does not provide a swing source for the forward and backward movement of the feed dog 91. Therefore, the feed shaft 51 also has no swing, and the feed dog 91 has no forward and backward feeding actions. Determining the stop of the feeding action of the feed dog 91 of the sewing machine realizes the main idea of the invention of this application. After determining the stop of the feeding action of the feed dog 91, the sewing machine immediately performs the thread cutting action, achieving the technical effect of no remaining thread in the thread cutting of this application sewing machine.

[0027] The above-mentioned thread cutting action starts when the sliding member 42 enters the stitch pitch positioning groove 212 from the first return groove 213 or the second return groove 214 and pushes the stitch pitch positioning groove 212, that is, the presser foot lifting action is also performed in the static state where the feed dog 91 stops the forward and backward feeding actions. Usually, the presser foot lifting action is performed after the thread cutting action is completed.

[0028] When the sliding member 42 inside the stitch pitch positioning wheel 21 starts to enter the stitch pitch positioning groove 212 and indirectly pushes the connecting rod 44 to make the long feed swing plate 33 and the short feed swing plate 32 flush, the rotating column 231 of the thread cutting crank wheel 23 applies a thrust to the thread cutting action surface 73 of the thread cutting fork wheel 71 within the thread cutting rotation angle of the drive motor 10, and then the thread cutting long shaft 76 is pushed by the thread cutting action surface 73 and the end thread cutting execution end performs the thread cutting action. The above-mentioned thread cutting long shaft 76 is hinged by the thread cutting connecting rod 75 and penetrates the entire machine body 45 through the end thread cutting execution end, that is, the thread cutting connecting rod 75 drives the thread cutting long shaft 76 from the thread cutting connecting rod 75 to the end thread cutting execution end 77.

[0029] The above-mentioned thread cutting fork wheel 71 is positioned on the fixed shaft 72 with the fixed shaft 72 as the rotation axis. The thread cutting working surface 73 and the thread cutting return working surface 74 of the thread cutting fork wheel 71 are pushed by the rotating column 231 and rotate along with the fixed shaft 72. The above-mentioned thread cutting working surface 73 is hinged with the thread cutting connecting rod 75. The thread cutting working surface 73 is forced to push the thread cutting connecting rod 75 downward. The thread cutting connecting rod 75 then pushes the thread cutting end execution end 76 to execute the thread cutting action, realizing the thread cutting in the static state when the feed dog 91 of the present application stops the front and back feeding actions.

[0030] The above-mentioned rotating column 231 is located between the thread cutting working surface 73 and the thread cutting return working surface 74. The rotating column 231 is in the idling stroke between the above two. During normal sewing, the stitch pitch positioning wheel 21 rotates the rotating column 231 in the above idling stroke driven by the swing connecting rod 53 by the main shaft motor 81. Therefore, the driving motor 10 of the sewing machine of the present application does not have an actual effect on thread cutting during normal sewing, and the rotating column 231 will not touch the thread cutting working surface 73 and the thread cutting return working surface 74 during other operations. The thread cutting return working surface 74 is used to make the whole thread cutting fork wheel 71 return to the original thread cutting position after thread cutting. When the rotating column 231 presses down the thread cutting working surface 73, that is, when the rotating column 231 rotates one week, it not only executes thread cutting but also completes the overall return of the thread cutting fork wheel 71.

[0031] After the sliding part 42 inside the stitch pitch positioning wheel 21 enters the stitch pitch positioning groove 212 to complete the thread cutting action, the sewing machine immediately executes the presser foot lifting action. The presser foot lifting cam 22 has a presser foot lifting working surface one 221, a presser foot lifting working surface two 222 and an idling surface 224. The presser foot highest point 223 is between the above-mentioned presser foot lifting working surface one 221 and the presser foot lifting working surface two 222. During thread cutting, the presser foot lifting ejector rod 61 abuts against the idling surface 224 of the presser foot lifting cam 22. Therefore, the driving motor 10 for normal sewing and thread cutting actions of the sewing machine does not have an actual operating effect on the presser foot.

[0032] The driving motor 10 performs the presser foot lifting action within the presser foot lifting angle. The presser foot mechanism has a presser foot cam 22 and a stitch pitch positioning wheel 21. The driving motor 10 drives the presser foot cam 22 to lift the presser foot ejector rod 61. The sliding member 42 can enter and push the stitch pitch positioning groove 212 from either the first return groove 213 or the second return groove 214, realizing the presser foot lifting action in the stationary state position of the feed dog 91 before and after the feeding action stops in the present application. In other words, when the stationary state of the feeding action of the feed dog 91 before and after the stop is the zero position of the swing seat 30, the sewing machine is at zero stitch pitch when the swing seat 30 is at the zero position, and the feed dog 91 has no forward and backward feeding swing angle. The original position of the feed dog 91 is below the needle plate, and without the forward and backward feeding swing angle, it naturally remains below the needle plate. Either the first presser foot acting surface 221 or the second presser foot acting surface 222 of the presser foot cam 22 can reach the highest point 223 of the presser foot for the presser foot ejector rod 61, and the presser foot ejector rod 61 can also return to the starting position from either the first return groove 213 or the second return groove 214. The above-mentioned presser foot ejector rod 61 is sleeved in the positioning sleeve 62. The presser foot ejector rod 61 is hinged to the presser foot lever 63, and the presser foot lever 63 is connected to the presser foot end actuator 64. Then, the presser foot end actuator 64 performs the presser foot lifting action. Through the above-mentioned presser foot lifting action, the sewing machine of the present application also realizes the presser foot lifting action in the stationary state position of the feed dog 91 before and after the feeding action stops, having a relatively high technical value.

[0033] The above is only the preferred embodiment of the present application, and does not limit the patent scope of the present application. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present application, or directly or indirectly applied in other related technical fields, shall be included in the patent protection scope of the present application by the same token.

Claims

1. A presser foot lifting mechanism for a sewing machine, including a feed dog (91), characterized in that, The presser foot lifting mechanism includes a presser foot lifting cam (22), a rotating lever (41), a presser foot lifting ejector rod (61), a positioning sleeve (62), a presser foot lifting lever (63), a presser foot final execution end (64), a drive motor (10), and a stitch pitch positioning wheel (21). The stitch pitch positioning wheel (21) and the presser foot lifting cam (22) are fixed on the output shaft (11) of the drive motor (10). The presser foot lifting cam (22) has a presser foot highest point (223). The rotating lever (41) has a sliding member (42). The stitch pitch positioning wheel (21) has a stitch pitch positioning groove (212). When the presser foot lifting ejector rod (61) abuts against the presser foot highest point (223), the sliding member (42) is located in the middle of the stitch pitch positioning groove (212). The feed dog (91) performs the presser foot lifting action by the presser foot lifting mechanism in the static state when the forward and backward feeding actions are stopped. The presser foot lifting ejector rod (61) is sleeved in the positioning sleeve (62). The presser foot lifting ejector rod (61) is hinged to the presser foot lifting lever (63). The presser foot lifting lever (63) is connected to the presser foot final execution end (64), and then the presser foot final execution end (64) performs the presser foot lifting action. The sliding member (42) indirectly pushes the swing seat (30). When the sliding member (42) enters the stitch pitch positioning groove (212), it indirectly determines the static state position of the feed dog (91) when the forward and backward feeding actions are stopped. When the static state of the feed dog (91) when the forward and backward feeding actions are stopped is the zero position of the swing seat (30), the sewing machine is at zero stitch pitch when the swing seat (30) is at the zero position. At this time, the swing seat (30) does not provide a swing source for the forward and backward movement of the feed dog (91).

2. The presser foot lifting mechanism of a sewing machine according to claim 1, characterized in that, The presser foot lifting cam (22) has a presser foot acting surface one (221) and a presser foot acting surface two (222). The stitch pitch positioning wheel (21) has a return groove one (213) and a return groove two (214).

3. The presser foot lifting mechanism of a sewing machine according to claim 2, characterized in that, The sliding member (42) enters the stitch pitch positioning groove (212) from the return groove one (213) or from the return groove two (214).

4. The presser foot lifting mechanism of a sewing machine according to claim 1, characterized in that, The drive motor (10) performs the presser foot lifting action within the presser foot rotation angle of the sewing machine.

5. The presser foot lifting mechanism of a sewing machine according to claim 2, wherein, The return groove one (213) or the return groove two (214) is used for the sliding member (42) to return to the stitch pitch positioning groove (212) at the maximum positive stitch pitch point (215) or the maximum negative stitch pitch point (216) of the swing seat (30). The maximum positive stitch pitch point (215) and the maximum negative stitch pitch point (216) are located at the end points of the stitch pitch adjustment groove (211).

6. The presser foot lifting mechanism of a sewing machine according to claim 1, characterized in that, The stitch pitch positioning groove (212) has an outer circular wall (21b) and an inner circular wall (21c). The sliding member (42) slides between the outer circular wall (21b) and the inner circular wall (21c).

7. The presser foot lifting mechanism of a sewing machine according to claim 1, characterized in that, The output shaft (11) is on the same concentric circular arc as the arc of the stitch pitch positioning groove (212).

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