Feed dog assembly, thread trimming mechanism and presser foot lifting mechanism for a sewing machine

Abstract

The application provides a feed dog assembly, a thread trimming mechanism and a presser foot lifting mechanism of a sewing machine, and particularly relates to the technical field of sewing machine manufacturing, and comprises a feed dog assembly, an up-down lifting power source and a front-rear feed power source, the feed dog assembly is jointly driven by the up-down lifting power source and the front-rear feed power source, the up-down lifting power source and the front-rear feed power source act on the feed dog assembly to perform a feed action of the sewing machine, the front-rear feed power source has a front output shaft to perform a thread trimming action of the thread trimming mechanism, and the front-rear feed power source has a rear output shaft to perform a presser foot lifting action of the presser foot lifting mechanism. The single power device can realize the thread trimming action and the presser foot lifting action under the control of an electric control system of the sewing machine, effectively improves the use efficiency of the power of the sewing machine, greatly reduces the manufacturing cost of the sewing machine, further improves the intelligent control level of the sewing machine, and has high use and promotion value.

Description

Technical Field

[0001] The present application proposes a feed dog assembly, a thread trimming mechanism and a presser foot lifting mechanism of a sewing machine, and specifically relates to the technical field of sewing machine manufacturing. Background Art

[0002] The feed dog is an essential component for sewing. Our company previously proposed a feed dog assembly for a separate sewing machine. The solution is to apply a non-lateral swing source to the feed dog through the up and down lifting drive source and the front and rear feed drive source of the feed dog assembly. The up and down lifting drive source and the front and rear feed drive source indirectly act on the feed dog to perform the feeding action. The front and rear feed drive sources drive the turntable and then drive the connecting rod. The connecting rod is movably connected to the eccentric position of the turntable, and the connecting rod is movably connected to the feed dog connecting frame. The swing source is transmitted to the feed dog assembly by the up and down lifting drive source and the front and rear feed drive source. The feed dog assembly can be added to the bottom line mechanism and can be manufactured into a modular assembly for use on various sewing machines. In the above-mentioned sewing machine, it is also necessary to add a thread trimming and presser foot lifting device, and it is necessary to add a power device to drive the above-mentioned thread trimming and presser foot lifting actions, which increases the manufacturing cost of the sewing machine. Summary of the Invention

[0003] In response to the problem of increased manufacturing costs in the existing sewing machines mentioned above, the present application specifically provides a feed dog assembly, a thread trimming mechanism and a presser foot lifting mechanism of a sewing machine to solve the above-mentioned defects, including a feed dog assembly, an upper and lower lifting power source and a front and rear feed power source, and is characterized in that the feed dog assembly is jointly driven by the upper and lower lifting power source and the front and rear feed power source, the upper and lower lifting power source and the front and rear feed power source act on the feed dog assembly to execute the feeding action of the sewing machine, the front output shafts of the front and rear feed power sources execute the thread trimming action of the thread trimming mechanism, and the rear output shafts of the front and rear feed power sources execute the presser foot lifting action of the presser foot lifting mechanism.

[0004] Preferably, a synchronous wheel is installed on the front output shaft, and the synchronous wheel indirectly drives the multi-stage cam 1 and the multi-stage cam 2 to realize the up and down feeding action of the feed dog assembly, and the output shaft of the up and down lifting power source is installed with a cam, and the operation of the cam indirectly acts on the feed dog frame to realize the forward and backward feeding action of the feed dog assembly, and the front output shaft is installed with a thread trimming crank, and the thread trimming crank acts on the thread trimming fork rod and then the thread trimming action is performed by the thread trimming terminal execution end, and the rear output shaft is installed with a presser foot lifting cam, and the presser foot lifting cam acts on the presser foot lifting push rod and then the presser foot lifting action is performed by the presser foot lifting terminal execution end.

[0005] Preferably, the up and down lifting power source uses connecting rods or synchronous wheels or gear technology to realize the forward and backward feeding action of the feed dog assembly; the front and rear feeding power source uses cams or connecting rods or synchronous wheels to realize the up and down lifting and feeding action of the feed dog assembly.

[0006] Preferably, the cam is matched with a swing rod, the cam drives the swing rod, the swing rod is hinged to the feed tooth frame, the operation positioning groove of the cam is matched with the swing shaft sleeve of the swing rod, and the swing shaft sleeve of the swing rod idles in the operation positioning groove.

[0007] Preferably, the multi-stage cam 1 and the multi-stage cam 2 are respectively located at the two ends of the bottom of the sewing machine bracket, and the multi-stage cam 1 and the multi-stage cam 2 are respectively fixed on the rotating shaft 1 and the rotating shaft 2, and the multi-stage cam 1 and the multi-stage cam 2 have convex point 1 and convex point 2, and the convex point 1 and convex point 2 act on the bottom of the bracket.

[0008] Preferably, a synchronous belt is sleeved on the synchronous pulley 1, and the synchronous pulley 1 drives the synchronous pulley 2 of the multi-stage cam 1; and the synchronous pulley 2 drives the synchronous pulley 3 of the multi-stage cam 2.

[0009] Preferably, the feed dog assembly is fixed on the feed dog fixing bracket, the feed dog assembly also has a swing rod, the swing rod is cylindrical, the swing hole has space for the swing rod to move up and down, the up and down lifting power source and the front and rear feeding power source have a fixed bracket one and a fixed bracket two, the fixed bracket one, the fixed bracket two and the feed dog fixing bracket body form a feed dog fixing bracket as a whole, the feed dog fixing bracket also has a limit block one and a limit block two, the limit block one and the limit block two are used for the feed dog frame and / or the bracket, the feed dog frame is provided with a support shaft, the support shaft is fixed on the feed dog frame, the support shaft extends to both ends of the bracket, and the support shaft is positioned to the two ends of the bracket with clearance fit.

[0010] Preferably, the front output shaft of the front and rear cloth feeding power source is equipped with a trimming crank, which acts on the trimming fork rod, and the trimming fork rod has a trimming rod and a return rod. The trimming crank has a sleeve, which is located between the trimming rod and the return rod, and the sleeve rotates back and forth between the trimming rod and the return rod on the trimming fork rod.

[0011] Preferably, the rear output shaft of the front and rear cloth feeding power source is equipped with a presser foot lifting cam, the cam portion of the presser foot lifting cam acts on the presser foot lifting push rod, and the presser foot lifting push rod acts on the presser foot lifting terminal to perform the presser foot lifting action.

[0012] Preferably, the operating angles of the front and rear cloth feeding power sources are respectively the cloth feeding action angle zone, the presser foot lifting action angle zone and the thread trimming action angle zone, and the sewing actions performed by the front and rear cloth feeding power sources are cloth feeding action, thread trimming action and presser foot lifting action in the order of the operation positioning groove formed by the presser foot lifting action angle zone and the thread trimming action angle zone and the rear output shaft.

[0013] Compared with the prior art, the feed dog assembly of the sewing machine is driven by the up-down lifting power source and the front-rear feed power source to perform the feed action of the sewing machine, the front-rear feed power source performs the thread cutting action and the presser foot lifting action in the idle time of performing the feed dog action, the single power device can realize the thread cutting action and the presser foot lifting action under the control of the electric control system of the sewing machine, the use efficiency of the power of the sewing machine is effectively improved, the manufacturing cost of the sewing machine is greatly reduced, the intelligent control level of the sewing machine is further improved, and the sewing machine has high use and promotion value. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 is a global view of the feed dog assembly, thread cutting mechanism and presser foot lifting mechanism of the sewing machine of the present application;

[0015] Figure 2 is a side view of the feed dog assembly of the feed dog assembly, thread cutting mechanism and presser foot lifting mechanism of the sewing machine of the present application;

[0016] Figure 3 is a configuration view of the feed dog assembly of the feed dog assembly, thread cutting mechanism and presser foot lifting mechanism of the sewing machine of the present application;

[0017] Figure 4 is an exploded view of the feed dog assembly of the feed dog assembly, thread cutting mechanism and presser foot lifting mechanism of the sewing machine of the present application;

[0018] Figure 5 is a configuration view of the feed dog assembly of the feed dog assembly, thread cutting mechanism and presser foot lifting mechanism of the sewing machine of the present application;

[0019] Figure 6 is an enlarged view of the cam configuration of the feed dog assembly, thread cutting mechanism and presser foot lifting mechanism of the sewing machine of the present application;

[0020] Figure 7 is a configuration view of the thread cutting mechanism of the feed dog assembly, thread cutting mechanism and presser foot lifting mechanism of the sewing machine of the present application;

[0021] Figure 8 is a schematic view of the feed dog assembly of the feed dog assembly, thread cutting mechanism and presser foot lifting mechanism of the sewing machine of the present application;

[0022] Figure 9 is a configuration view of the feed dog fixing support of the feed dog assembly, thread cutting mechanism and presser foot lifting mechanism of the sewing machine of the present application.

[0023] Reference numerals: feed dog assembly 1a, thread trimming mechanism 1b, presser foot lifting mechanism 1c, up and down lifting power source 10, cam 11, positioning groove 111, feed dog frame 12, output shaft 13, support shaft 15, bracket 16, swing lever 17, swing lever 18, swing sleeve 181, front and rear feed power source 20, feed action corner area 2a, presser foot lifting action corner area 2b, thread trimming action corner area 2c, front output shaft 21, synchronous pulley 211, multi-stage cam 212, convex point 2 121, multi-stage cam 213, convex point 2131, synchronous pulley 214, synchronous pulley 3 215, rotating shaft 1 216, rotating shaft 217, rear output shaft 22, thread trimming crank 23, sleeve 231, thread trimming fork rod 24, thread trimming rod 241, return rod 242, thread trimming end execution end 25, presser foot lifting cam 26, presser foot lifting push rod 27, feed dog fixing bracket 30, swing amplitude hole 31, fixing bracket 1 32, fixing bracket 2 33, limit block 1 34, limit block 2 35. DETAILED DESCRIPTION

[0024] The following is combined with Figures 1-9 The preferred embodiments of the present application are described in detail so that the advantages and features of the present application can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present application. These embodiments are only used to illustrate the present invention and are not intended to limit the present invention.

[0025] Example 1

[0026] The present application proposes a feed dog assembly, a thread trimming mechanism, and a presser foot lifting mechanism for a sewing machine, comprising a feed dog assembly 1a, a thread trimming mechanism 1b, a presser foot lifting mechanism 1c, an up and down lifting power source 10, and a front and rear feed power source 20. The feed dog assembly 1a is driven jointly by the up and down lifting power source 10 and the front and rear feed power source 20. The up and down lifting power source 10 and the front and rear feed power source 20 act together on the feed dog assembly 1a to perform the feed action of the sewing machine, so that the feed dog assembly 1a has the function of feeding sewing. After the feed action is completed, the front and rear feed power sources 20 start to drive the thread trimming mechanism 1b and the presser foot lifting mechanism 1c to perform the thread trimming action and the presser foot lifting action. First, the front output shaft 21 of the front and rear feed power source 20 performs the thread trimming action of the thread trimming mechanism 1b, and then the rear output shaft 22 of the front and rear feed power source 20 performs the presser foot lifting action of the presser foot lifting mechanism 1c. The present application utilizes the front and rear cloth feeding power sources 20 of the cloth feeding dog assembly 1a to perform the thread cutting action and the presser foot lifting action after completing the cloth feeding action, thereby improving the utilization rate of the sewing machine power device and significantly reducing the manufacturing cost of the sewing machine.

[0027] The front output shaft 21 of the front and back feed power source 20 is provided with the cam 11; the output shaft 13 of the up and down lifting power source 10 is provided with the synchronous pulley 211, the cam 11 indirectly acts on the feed dog holder 12 to realize the front and back feed action of the feed dog assembly 1a, and the synchronous pulley 211 indirectly acts on the support 16 to realize the up and down lifting feed action of the feed dog assembly 1a, the front and back feed action and the up and down lifting feed action are performed at the same time to realize the feed action of the sewing machine.

[0028] The cam 11 is provided with the operation positioning groove 111, which is provided with the feed action corner area 2a, the presser foot lifting action corner area 2b and the thread cutting action corner area 2c. In the feed action corner area 2a of the front and back feed power source 20, the cam 11 matched with the swing rod 18 is installed on the output shaft 13, the cam 11 drives the swing rod 18 in the feed action corner area 2a, the swing rod 18 hingedly drives the feed dog holder 12 to make the output shaft 13 generate the swing source of the front and back movement of the feed dog holder 12. The presser foot lifting action corner area 2b and the thread cutting action corner area 2c of the cam 11 are idle strokes, and the front and back feed power source 20 performs the thread cutting action and the presser foot lifting action by using the idle strokes of the cam 11.

[0029] The feed dog holder 12 is provided with the support shaft 15, which is fixed on the feed dog holder 12 and extends to the two ends of the support 16, and is clearance-fitted in the two ends of the support 16, and the feed dog holder 12 operates in the support 16.

[0030] The front output shaft 21 is provided with the synchronous pulley 211, which indirectly drives the multi-stage cam 212 and the multi-stage cam 213 to realize the up and down lifting feed action of the entire feed dog assembly 1a.

[0031] The multi-stage cam 212 and the multi-stage cam 213 are respectively located at the two ends of the bottom of the support 16. The synchronous pulley 211 is provided with a synchronous belt, the synchronous pulley 211 drives the synchronous pulley 214 of the multi-stage cam 212, and the synchronous pulley 214 drives the synchronous pulley 215 of the multi-stage cam 213. The up and down lifting power source 10 drives the synchronous pulley 211 and the synchronous pulley 215 in the feed action corner area 2a, so as to drive the multi-stage cam 212 and the multi-stage cam 213 to generate the swing source.

[0032] The feed dog assembly 1a of the present application is fixed to the feed dog bracket 30. Specifically, the multi-stage cam 1 212 is fixed to the rotating shaft 1 216, and the multi-stage cam 2 213 is fixed to the rotating shaft 217. The rotating shafts 116 and 217 are sleeved on the feed dog bracket 30. The multi-stage cam 1 212 and the multi-stage cam 2 213 have protrusions 1 2121 and 2131. The arrangement of protrusions 1 2121 and 2131 enables the bracket 16 and the feed dog assembly 1a to generate an upward and downward swing. The feed dog assembly 1a also has a swing lever 17, which is cylindrical. The feed dog fixing bracket 30 also has a swing hole 31, which provides space for the swing rod 17 to move up and down. The swing amplitude of the multi-stage cam 1 212 and the multi-stage cam 2 213 is limited by the swing hole 31 of the feed dog fixing bracket 30. Furthermore, the feed dog fixing bracket 30 also includes a fixing bracket 1 32 and a fixing bracket 2 33, which secure the vertical lifting power source 10 and the forward and backward feed power source 20. The fixing bracket 1 32, the fixing bracket 2 33, and the feed dog fixing bracket 30 body form a single unit fixed to the sewing machine. The feed dog fixing bracket 30 also includes a stop block 1 34 and a stop block 2 35, which are used to define the operating position of the feed dog frame 12 and / or the bracket 16, ensuring that the feed dog assembly 1a maintains a fixed operating structure within the feed dog fixing bracket 30.

[0033] After the cloth feeding action of the above-mentioned sewing machine is completed, sewing is finished, and the front and rear cloth feeding power sources 20 begin to perform the thread trimming action and the presser foot lifting action. The front output shaft 21 of the above-mentioned front and rear cloth feeding power sources 20 is installed with a thread trimming crank 23. The thread trimming crank 23 acts on the thread trimming fork rod 24, and the thread trimming fork rod 24 then acts on the thread trimming end execution end 25 to perform the thread trimming action. The thread trimming fork rod 24 has a thread trimming rod 241 and a return rod 242. The thread trimming crank 23 has a shaft sleeve 231. The shaft sleeve 231 is located between the thread trimming rod 241 and the return rod 242. The shaft sleeve 231 pushes the thread trimming rod 241 to perform thread trimming, and the shaft sleeve 231 pushes the return rod 242 to perform thread trimming return. The positions of the thread trimming rod 241 and the return rod 242 on the thread trimming fork rod 24 can be interchanged, and the technical effects achieved are the same.

[0034] The rear output shaft 22 of the above-mentioned front and rear cloth feeding power source 20 is installed with a presser foot lifting cam 26. Under the drive of the front and rear cloth feeding power source 20, the cam portion of the presser foot lifting cam 26 acts on the presser foot lifting push rod 27, and then the presser foot lifting push rod 27 acts on the presser foot lifting end to perform the presser foot lifting action.

[0035] The cloth feeding action, presser foot lifting action, and thread trimming action are located in the operating angles of the front and rear cloth feeding power sources 20, namely the cloth feeding action angle zone 2a, the presser foot lifting action angle zone 2b, and the thread trimming action angle zone 2c, respectively. The sewing actions performed by the front and rear cloth feeding power sources 20 are cloth feeding action, thread trimming action, and presser foot lifting action in the following order. It is worth noting that after the front and rear cloth feeding power sources 20 complete the cloth feeding action and the sewing machine stops, the front and rear cloth feeding power sources 20 shift their operating angles to perform the thread trimming action and presser foot lifting action. In other words, the cloth feeding action, presser foot lifting action, and thread trimming action do not overlap in the operating angle zones of the front and rear cloth feeding power sources 20. After the machine stops, the thread trimming is performed first and then the presser foot lifting action.

[0036] In the cloth feed corner region 2a, the front and rear cloth feed power sources 20 push the cam 11 against the swing sleeve 181 located in the cloth feed corner region 2a, causing the swing lever 18 to generate a forward and backward cloth feed swing source. When sewing is completed, the front and rear cloth feed power sources 20 exit the cloth feed corner region 2a and enter the presser foot lifter corner region 2b and the thread trimmer corner region 2c. Because the operating positioning groove 111 formed by the presser foot lifter corner region 2b and the thread trimmer corner region 2c is concentric with the rear output shaft 22 (or the front output shaft 21), the front and rear cloth feed power sources 20 entering the operating positioning groove 111 do not generate a forward and backward cloth feed swing source for the swing lever 18. The swing sleeve 181 of the swing lever 18 merely idles in the operating positioning groove 111. Similarly, when the front and rear cloth feeding power sources 20 are operating in the cloth feeding action corner area 2a, the shaft sleeve 231 of the crank 23 idles back and forth between the thread trimming fork rod 24 and the thread trimming rod 241 and the return rod 242; and the arc of the presser foot lifting cam 26 also idles back and forth facing the presser foot lifting push rod 27. In this way, the cloth feeding action, presser foot lifting action and thread trimming action performed by the front and rear cloth feeding power sources 20 do not affect each other, and the actions are clear and distinct.

[0037] Example 2

[0038] The second embodiment of the present invention is basically the same as the first embodiment described above, except that the upper and lower lifting power source 10 and the front and rear cloth feeding power source 20 have different means for implementing the swing source generated by the feed dog assembly 1a. In addition to the upper and lower lifting power source 10 using the cam 11 to control the feed dog assembly 1a, the upper and lower lifting power source 10 also uses connecting rods, synchronous wheels, gears and other technical means to achieve the above purpose; in addition to the front and rear cloth feeding power source 20 using the synchronous pulley 211, the front and rear cloth feeding power source 20 also uses cams, connecting rods or synchronous wheels and other technologies to achieve the above purpose.

[0039] The above description is only a 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 using the contents of the present application specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A sewing machine comprising a feed dog assembly, a thread trimming mechanism and a presser foot lifting mechanism, comprising a feed dog assembly (1a), an up and down lifting power source (10) and a front and back feeding power source (20), characterized in that: The feed dog assembly (1a) is driven by an upper and lower lifting power source (10) and a front and rear feed power source (20). The upper and lower lifting power source (10) and the front and rear feed power source (20) act on the feed dog assembly (1a) to perform the cloth feeding action of the sewing machine. The front output shaft (21) of the front and rear feed power source (20) performs the thread cutting action of the thread cutting mechanism (1b), and the rear output shaft (22) of the front and rear feed power source (20) performs the presser foot lifting action of the presser foot lifting mechanism (1c). The front output shaft (21) is provided with a synchronous pulley 1 (211), and the synchronous pulley 1 (211) indirectly drives the multi-stage cam 1 (212) and the multi-stage cam 2 (213) to realize the up-and-down feeding action of the feed tooth assembly (1a). The up-and-down feeding power source (10) has an output shaft (13) provided with a cam (11), and the cam (11) operates to indirectly act on the feed tooth frame (12) to realize the forward and backward feeding action of the feed tooth assembly (1a). The cam (11) is matched with a swing rod (18), and the cam (11) drives the swing rod (18). The swing rod (18) is hinged to the feed tooth frame (12). The operation positioning groove of the cam (11) (111) matching the swing shaft sleeve (181) of the swing lever (18), the swing shaft sleeve (181) of the swing lever (18) idles in the operation positioning groove (111), the multi-stage cam 1 (212) and the multi-stage cam 2 (213) are respectively located at two ends of the bottom of the bracket (16) of the sewing machine, the multi-stage cam 1 (212) and the multi-stage cam 2 (213) are respectively fixed on the rotating shaft 1 (216) and the rotating shaft 2 (217), the multi-stage cam 1 (212) and the multi-stage cam 2 (213) have a convex point 1 (2121) and a convex point 2 (2131), and the convex point 1 (2121) and the convex point 2 (2131) act on the bottom of the bracket (16); The front output shaft (21) is equipped with a trimming crank (23), the trimming crank (23) acts on the trimming fork lever (24), and the trimming end execution end (25) performs the trimming action. The front output shaft (21) of the front and rear cloth feeding power source (20) is equipped with a trimming crank (23), the trimming crank (23) acts on the trimming fork lever (24), the trimming fork lever (24) has a trimming lever (241) and a return lever (242), the trimming crank (23) acts on the trimming fork lever (24), and the trimming fork lever (24) has a trimming lever (241) and a return lever (242). The handle (23) has a shaft sleeve (231), and the shaft sleeve (231) is located between the thread trimming rod (241) and the return rod (242). The shaft sleeve (231) rotates back and forth between the thread trimming fork rod (24) and the thread trimming rod (241) and the return rod (242). The rear output shaft (22) is equipped with a presser foot lifting cam (26). The presser foot lifting cam (26) acts on the presser foot lifting push rod (27), and then the presser foot lifting end performs the presser foot lifting action.

2. A sewing machine comprising a feed dog assembly, a thread trimming mechanism and a presser foot lifting mechanism according to claim 1, characterized in that: The up-and-down lifting power source (10) realizes the forward and backward cloth feeding action of the cloth feeding dog assembly (1a) by means of connecting rods, synchronous wheels or gears; the forward and backward cloth feeding power source (20) realizes the up-and-down lifting cloth feeding action of the cloth feeding dog assembly (1a) by means of cams, connecting rods or synchronous wheels.

3. A sewing machine comprising a feed dog assembly, a thread trimming mechanism and a presser foot lifting mechanism according to claim 1, characterized in that: A synchronous belt is sleeved on the synchronous pulley 1 (211), and the synchronous pulley 1 (211) drives the multi-stage cam 1 (212) and the synchronous pulley 2 (214); the synchronous pulley 2 (214) drives the multi-stage cam 2 (213) and the synchronous pulley 3 (215).

4. A sewing machine comprising a feed dog assembly, a thread trimming mechanism and a presser foot lifting mechanism according to claim 1, characterized in that: The feed dog assembly (1a) is fixed on the feed dog fixed bracket (30), and the feed dog assembly (1a) also has a swing rod (17), and the swing rod (17) is cylindrical. The feed dog fixed bracket (30) also has a swing hole (31), and the swing hole (31) has a space for the swing rod (17) to move up and down. The up and down lifting power source (10) and the front and back feeding power source (20) have a fixed bracket 1 (32) and a fixed bracket 2 (33), and the fixed bracket 1 (32) and the fixed bracket 2 (33) are connected to each other. The second frame (33) and the feed dog fixing bracket (30) body form a feed dog fixing bracket (30) as a whole. The feed dog fixing bracket (30) also has a limit block (34) and a limit block (35). The limit block (34) and the limit block (35) are used for the feed dog frame (12) and / or the bracket (16). The feed dog frame (12) is provided with a support shaft (15). The support shaft (15) is fixed on the feed dog frame (12). The support shaft (15) is positioned at both ends of the bracket (16) with clearance fit.

5. A sewing machine comprising a feed dog assembly, a thread trimming mechanism and a presser foot lifting mechanism according to claim 1, characterized in that: The rear output shaft (22) of the front and rear cloth feeding power source (20) is provided with a presser foot lifting cam (26), the cam portion of the presser foot lifting cam (26) acts on a presser foot lifting push rod (27), and the presser foot lifting push rod (27) acts on the presser foot lifting end to perform the presser foot lifting action.

6. A sewing machine comprising a feed dog assembly, a thread trimming mechanism and a presser foot lifting mechanism according to claim 1, characterized in that: The operating angles of the front and rear cloth feeding power sources (20) are respectively cloth feeding action angle area (2a), presser foot lifting action angle area (2b) and thread trimming action angle area (2c); the sewing actions performed by the front and rear cloth feeding power sources (20) are cloth feeding action, thread trimming action and presser foot lifting action in the order of sequence; the operation positioning groove (111) formed by the presser foot lifting action angle area (2b) and the thread trimming action angle area (2c) is concentric with the rear output shaft (22).

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