Presser foot device of sewing machine

Abstract

This invention relates to a presser foot device for a sewing machine, comprising a presser foot mechanism, a spring-loaded mechanism, an actuation mechanism, and a control module. The presser foot mechanism includes a presser foot bar and a presser foot. The spring-loaded mechanism includes a rod, an elastic element, and a swinging component. The actuation mechanism includes an actuator and an output shaft, with the output shaft connected to the swinging component. The control module is electrically connected to the actuation mechanism and includes a sensing unit corresponding to the presser foot bar for sensing changes in its displacement. When the fabric becomes thicker, the presser foot bar is pushed upwards. After the sensing unit feeds the signal of the presser foot bar change to the control module, the output shaft drives the spring-loaded mechanism to rise upwards, thereby maintaining a constant force applied by the presser foot to the fabric. This achieves consistent thread spacing throughout the sewing.

Description

Technical Field

[0001] This invention relates to the technology of a sewing machine, and more particularly to a presser foot device for a sewing machine. Background Technology

[0002] The presser foot mechanism of existing sewing machines mainly relies on the compression force of a spring to firmly press the bottom surface of the presser foot against a fixed area of ​​the sewing platform. This pressing force acts on the fabric primarily to clamp it between the presser foot and the sewing platform, creating a certain degree of friction. The feed tooth, through a transmission mechanism, generates a counterclockwise cyclical motion along an approximately elliptical trajectory. This causes the feed tooth to rise relative to the sewing platform, move horizontally to the left, and then sink back down, repeating this cycle. Through this repetitive cyclical operation, when the tooth surface of the feed tooth is higher than the sewing platform, it lifts the fabric and presser foot, clamping the fabric between them. Then, the feed tooth moves horizontally to the left. At this point, because the friction between the feed tooth and the fabric is greater than the friction between the fabric and the bottom surface of the presser foot, the fabric moves a certain distance along with the feed tooth, and this cycle repeats continuously.

[0003] However, due to the continuous operation of the machine, the fabric will undergo a horizontal displacement to the left in accordance with the machine's operating frequency. However, this displacement will not be completely consistent with the horizontal displacement of the feed teeth; there will be a certain percentage of slippage. The magnitude of this slippage depends on the magnitude of the force applied to the presser foot bar, because the magnitude of this force affects the magnitude of the friction between the fabric and the bottom surface of the presser foot, as well as the magnitude of the friction between the fabric and the feed teeth. The greater the difference between the friction between the fabric and the feed teeth and the friction between the fabric and the bottom surface of the presser foot, the smaller the slippage will be, and the closer the horizontal displacement of the fabric will be to the horizontal displacement of the feed teeth, and vice versa.

[0004] As mentioned above, a drawback of the existing implementation is that while the force acting on the bottom of the presser foot can be adjusted by manually adjusting the compression of the spring on the presser foot lever, the thickness of the fabric may vary randomly during sewing (e.g., during stitching or overlapping). In the implementation, the fabric thickness often increases by two or four times. When the fabric thickness increases, the presser foot must be raised higher to accommodate the thicker fabric between the presser foot and the feed teeth. It's understandable that moving the presser foot upwards will compress the spring more via the presser foot lever, resulting in increased force applied to the fabric. This increased force alters the friction between the presser foot and the fabric, as well as between the feed teeth and the fabric. This change in friction alters the slip ratio, causing the horizontal displacement of the fabric to differ when the fabric thickness remains constant from when the fabric becomes thicker. This results in inconsistent stitch spacing, ultimately affecting the aesthetics of the finished product.

[0005] In addition to the aforementioned issues, the presser foot device must be operated by a mechanism to lift the presser foot, releasing the pressure on the fabric or allowing the fabric to be placed on or removed from the sewing platform. In existing embodiments, this mainly includes a lever mechanism, a rotating shaft, and a presser foot lifting mechanism. Applying force to the lever mechanism rotates the shaft, which in turn drives the presser foot lifting mechanism to pull the presser foot and presser foot upwards together, releasing the pressure on the fabric. When the applied force is released, the presser foot returns to its original state. The applied force can be operated manually, pneumatically, or electromagnetically. Regardless of the force used, it relies on adding auxiliary or force-applying actuation units to the original mechanical structure. The disadvantages include a complex and space-consuming transmission chain, the need for costly force-applying actuation units, high noise levels, and the inability to control the presser foot's lifting displacement.

[0006] In view of this, the inventor has devoted himself to research and applied theoretical principles to address the shortcomings of the prior art, and has made every effort to solve the above-mentioned problems, which is the target of the inventor's improvement. Summary of the Invention

[0007] One objective of this invention is to provide a presser foot device for a sewing machine, which can achieve consistent thread spacing in response to changes in fabric thickness or various fabric thicknesses during sewing.

[0008] To achieve the above objectives, the present invention provides a presser foot device for a sewing machine, applied to the sewing of a fabric. The sewing machine includes a machine body, and the presser foot device includes a presser foot mechanism, a spring action mechanism, a linkage mechanism, and a control module. The presser foot mechanism includes a presser foot rod and a presser foot connected to the presser foot rod, the presser foot rod passing through the machine body. The spring action mechanism includes a rod, an elastic element, and a swinging component. The rod is movably connected to the presser foot rod, the swinging component is disposed on the rod, and the elastic element is disposed between the swinging component and the presser foot rod. An actuation mechanism is fixed to the machine body. The actuation mechanism includes an actuator and an output shaft driven by the actuator. The output shaft is connected to the oscillating component. The control module is electrically connected to the actuation mechanism. The control module includes a sensing unit, which is configured to sense the displacement change of the presser foot. When the fabric becomes thicker, the presser foot will be pushed upward. After the sensing unit feeds the signal of the presser foot change to the control module, the output shaft will drive the elastic action mechanism to lift upward, thereby keeping the force exerted by the presser foot on the fabric constant.

[0009] Another object of the present invention is to provide a presser foot device for a sewing machine, which can control the amount of presser foot lifting displacement according to the needs of a specific sewing process.

[0010] This invention also has the following advantages: it can significantly reduce the material, manufacturing, and assembly costs of components such as manual turning. It also boasts advantages such as simplified mechanical structure, compact size, and easy installation.

[0011] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the present invention. Attached Figure Description

[0012] Figure 1 This is an external view of the presser foot device of the present invention combined with a sewing machine.

[0013] Figure 2 This is a partial enlarged view of the presser foot device of the present invention integrated into a sewing machine.

[0014] Figure 3 This is a schematic diagram of the combination of the presser foot mechanism and the elastic action mechanism of the present invention.

[0015] Figure 4 The front view of the presser foot mechanism of the present invention after it has been lifted upwards.

[0016] Figure 5 This is a block diagram of the presser foot device of the present invention.

[0017] Figure 6 The presser foot device of this invention is shown in the front view when applied to sewing general fabrics.

[0018] Figure 7 The presser foot device of this invention is shown in the front view when applied to sewing thick fabric.

[0019] 1: Presser foot device

[0020] 10: Presser foot mechanism

[0021] 11: Presser foot bar

[0022] 111: Card slot

[0023] 12: Presser foot

[0024] 13: Snap ring

[0025] 14: Fabric thickness sensing head

[0026] 20: Elastic action mechanism

[0027] 21: Rods

[0028] 211: Snap-in groove

[0029] 22: Elastic element

[0030] 23: Pendulum component

[0031] 231: Column

[0032] 232: Cam Shaft

[0033] 233: Linkage

[0034] 234: Slot

[0035] 235: Shaft

[0036] 24: Buckle

[0037] 25: Spring compression sensing head

[0038] 30: Actuation mechanism

[0039] 31: Actuator

[0040] 32: Actuation power transmission component

[0041] 33: Output shaft

[0042] 40: Control Module

[0043] 41: Sensing Unit

[0044] 411: Fabric thickness sensor

[0045] 412: Spring Compression Sensor

[0046] 42: Control Unit

[0047] 43: Motor drive unit

[0048] 44: Spindle drive unit

[0049] 45: Setting / Operation Unit

[0050] 46: Display Unit

[0051] 8: Sewing machine

[0052] 80: Body

[0053] 81: Base

[0054] 811: Sewing Platform

[0055] 812: Needle plate

[0056] 813: Feeding teeth

[0057] 82: Arm

[0058] 9: Fabric

[0059] 9A: Thick fabric Detailed Implementation

[0060] The structural and working principles of the present invention will be described in detail below with reference to the accompanying drawings:

[0061] Please see Figures 1 to 5 As shown, the present invention provides a presser foot device for a sewing machine. The sewing machine 8 includes a body 80, which includes a base 81 and a machine arm 82 attached to the base 81. Various transmission mechanisms or devices (not shown) are interconnected and disposed inside the machine arm 82 and the base 81. A sewing platform 811, a needle plate 812, and a feed tooth 813 are formed on the left side of the base 81. A presser foot device 1 and a needle bar mechanism (not shown) and other related components are disposed on the left side of the machine arm 82.

[0062] The presser foot device 1 in this embodiment mainly includes a presser foot mechanism 10, a spring action mechanism 20, a motion mechanism 30, and a control module 40.

[0063] The presser foot mechanism 10 mainly includes a presser foot rod 11 and a presser foot 12. The presser foot rod 11 passes through the aforementioned machine arm 82, and the presser foot 12 is fixed at the end of the presser foot rod 11 that protrudes from the machine arm 82. When the presser foot rod 11 is driven, it can move up and down relative to the machine arm 82. The presser foot 12 is positioned corresponding to the aforementioned needle plate 812 and works in conjunction with the fabric feed tooth 813.

[0064] The elastic action mechanism 20 mainly includes a rod 21, an elastic element 22, and a swinging component 23. In this embodiment, the rod 21 is a hollow sleeve, but its shape is not limited to this. This rod 21 is movably sleeved on the upper part of the aforementioned presser foot rod 11. The swinging component 23 mainly includes a column 231 and a connecting rod 233. The column 231 is inserted through and fixed to the upper part of the rod 21. A convex shaft 232 is connected to the side of the column 231. One end of the connecting rod 233 is provided with a strip groove 234. The connecting rod 233 is pivotally connected to the convex shaft 232 through the strip groove 234, so that the convex shaft 232 can pivot and slide within the strip groove 234. In this embodiment, the elastic element 22 is a compression spring. This elastic element 22 is housed inside the aforementioned rod 21 and is elastically clamped between the column 231 and the presser foot rod 11. Furthermore, the swing component 23 also includes a shaft 235, one end of which is fixed inside the column 231, and the other end is inserted into the upper part of the presser foot rod 11, thereby improving the stability of the rod 21 and the presser foot rod 11 during sliding.

[0065] Furthermore, a groove 211 is provided at the lower part of the rod 21 to provide a fastening ring 24; a slot 111 is provided at the upper part of the presser foot rod 11 to provide a fastening ring 13, wherein the two ends of the aforementioned elastic element 22 respectively abut against the corresponding surfaces of the ring 13 and the column 231, the ring 13 is formed above the fastening ring 24, and they restrict and block each other to prevent the presser foot rod 11 from detaching from the rod 21.

[0066] The actuation mechanism 30 is fixed inside the arm 82 and mainly includes an actuator 31, a power transmission assembly 32 and an output shaft 33. In this embodiment, the actuator 31 is a motor, which is fixed to the arm 82 by bolts or other locking elements. In this embodiment, the power transmission assembly 32 is a reduction gear set, which is disposed between the actuator 31 and the output shaft 33. The actuator 31 transmits power to the output shaft 33 through the power transmission assembly 32. The output shaft 33 is fixed to the other end of the aforementioned connecting rod 233.

[0067] The control module 40 includes one or more types of sensors. One purpose of these sensors is to sense changes in the displacement of the presser foot lever 11, while another purpose is to sense changes in the compression of the elastic element 22, corresponding to the elastic action mechanism 20. After these two change signals are fed back to the control module 40, the control module 40 enables the actuation mechanism 30 to perform two dynamic controls. The first dynamic control aims to enable the presser foot 12 to rise and fall in a range-controlled manner; the second dynamic control aims to enable the compression of the elastic element 22 in the elastic action mechanism 20 to be range-controlled. Based on these two dynamic controls, multiple electronic sewing functions can be realized. For example, control of slightly lifting the presser foot when it is too thick, control of constant or variable presser foot force, numericalization of presser foot force, control and numericalization of presser foot displacement, etc.

[0068] In this embodiment, the control module 40 is electrically connected to the actuator 30, and it mainly includes a sensing unit 41, a control unit 42, a motor drive unit 43, a spindle drive unit 44, a setting / operation unit 45, a display unit 46, and other related components. The motor drive unit 43 is electrically connected to the aforementioned actuator 31, the spindle drive unit 44 is electrically connected to the control unit 42 and the spindle motor of the sewing machine 8, and the setting / operation unit 45 and the display unit 46 are electrically connected to the control unit 42, respectively.

[0069] Furthermore, the sensing unit 41 in this embodiment mainly includes a fabric thickness sensor 411 and a spring compression sensor 412, wherein the fabric thickness sensor 411 is used to sense the change in the amount of movement of the presser foot 11, and the spring compression sensor 412 is used to sense the change in the amount of compression of the elastic element 22.

[0070] Furthermore, a fabric thickness sensing head 14 is connected inside the presser foot bar 11 located in the machine arm 82. The fabric thickness sensor 411 is configured corresponding to the fabric thickness sensing head 14, fixed inside the machine arm 82, and electrically connected to the control unit 42, so that the fabric thickness can be detected by the fabric thickness sensor 411 during the up and down movement of the presser foot bar 11.

[0071] Furthermore, a spring compression sensing head 25 is provided on the top surface of the aforementioned rod 21. The aforementioned spring compression sensor 412 is configured corresponding to the spring compression sensing head 25, fixed inside the arm 82, and electrically connected to the aforementioned control unit 42, so as to obtain the detection of the rod 21 through the spring compression sensor 412.

[0072] Please see Figure 4As shown, the presser foot device of the sewing machine of the present invention can also be used as the lifting mechanism of the presser foot 10. When the actuator 31 is energized and the swing component 23 rotates counterclockwise, the vertical force applied to the rod 21 will be upward, so the rod 21 will be pulled up. While the rod 21 is pulled up, the amount of compression of the elastic element 22 will gradually decrease until the buckle 24 of the rod 21 touches the retaining ring 13 of the presser foot rod 11. If the rod 21 is continuously pulled up, the presser foot rod 11 will be pulled up together with the presser foot 12.

[0073] Please see Figure 6 and Figure 7 As shown, the presser foot device of the sewing machine of the present invention can be applied to a fabric 9, a thick fabric 9A, and a lap. When sewing the fabric 9, the compression amount of the elastic element 22 can be set in advance by the control module 40. This compression amount can be quantified as the magnitude of the force. The control module 40 will drive the actuator 31 to operate. After the actuator 31 is powered on, the swing component 23 will rotate clockwise. The vertical force applied to the rod 21 will then be downward, so the rod 21 will be driven downward and... The presser foot 12 and presser foot 11 move downwards until the presser foot 12 touches the fabric 9. The fabric thickness sensor 411 detects the thickness of the fabric 9. When the presser foot 12 touches the fabric 9, if the actuator 31 continues to rotate clockwise, the presser foot 12 begins to press the fabric 9. The spring compression sensor 412 detects the current compression amount and compares it. Then, the control rod 21 starts to compress the elastic element 22 to increase the force applied by the presser foot 12 to the fabric 9 to the set target compression amount.

[0074] Continuing from the above, when sewing thick fabric 9A, the compression amount of elastic element 22 can be set in advance through control module 40. After the actuator 31 is powered on, the swing component 23 rotates counterclockwise. The current compression amount is known and compared through spring compression sensor 412. Then, the vertical force applied to the rod 21 is controlled to be upward. Therefore, the rod 21 will be pulled up by a displacement. While the rod 21 is pulled up, the amount of compression of elastic element 22 will gradually decrease to reduce the increased compression amount of elastic element 22 caused by thick fabric 9A.

[0075] Therefore, in summary the above... Figure 6 and Figure 7 The implementation example shown illustrates that as long as the target compression amount of the elastic element 22 is set in advance through the control module 40, the compression amount of the elastic element 22 will be maintained at the pre-set target value regardless of the thickness of the fabric placed on the sewing platform 811.

[0076] Furthermore, if the above... Figure 6 and Figure 7The illustrated implementation case illustrates a continuous operation process, namely the overlapping stitching process. The fabric thickness sensor 411 and / or the spring compression sensor 412 sense that when the fabric 9 moves stably in a predetermined direction, and the fabric 9 changes to a thicker fabric 9A, the fabric thickness sensor 411 and / or the spring compression sensor 412 feed the signal to the control module 40. The control module 40 immediately sends a correction signal to the motor drive unit 43 and drives the actuator 31 to operate, raising the rod 21 to match the increase in fabric thickness. This ensures that the force applied by the presser foot 12 to the fabric 9 and the force applied to the thicker fabric 9A remain constant, thus preventing the stitch spacing from changing due to the compression of the elastic element 22.

[0077] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the appended claims.

Claims

1. A presser foot device of a sewing machine for sewing a cloth, the sewing machine comprising a machine body, characterized in that, The presser device comprises: a presser mechanism including a presser rod and a presser connected to the presser rod, the presser rod being connected to the machine body; a spring action mechanism including a rod, a spring and a swing component, the rod being a hollow sleeve, the hollow sleeve being movably connected to the upper part of the presser rod, the swing component including a column and a connecting rod, the column being connected to the upper part of the rod and fixed in the rod, the spring being a compression spring, the compression spring being accommodated in the hollow sleeve and elastically clamped between the column and the presser rod, the column being connected to a convex shaft, a buckle groove being provided at the lower part of the hollow sleeve to provide a buckle ring fastening, a clamping groove being provided at the upper part of the presser rod to provide a clamping ring fastening, the clamping ring being formed above the buckle ring and being limited and blocked to each other; an actuating mechanism fixed to the machine body, the actuating mechanism including an actuator and an output shaft driven by the actuator, the two ends of the connecting rod being respectively pivoted to the convex shaft and fixed to the output shaft; and a control module electrically connected to the actuating mechanism, the control module including a sensing unit arranged corresponding to the presser rod and used to sense the displacement change of the presser rod; wherein when the fabric becomes thicker, the presser rod will be pushed up, after the sensing unit feeds the signal of the presser rod change to the control module, the output shaft will drive the spring action mechanism to be lifted up, so that the force applied by the presser on the fabric remains constant.

2. The presser foot device of the sewing machine according to claim 1, wherein The sensing unit includes a fabric thickness sensor, a fabric thickness sensing head being connected to the presser rod, the fabric thickness sensor being arranged corresponding to the fabric thickness sensing head and sensing.

3. The presser foot device of a sewing machine according to claim 1 or 2, wherein The sensing unit includes a spring compression amount sensor, a spring compression amount sensing head being arranged at the rod, the spring compression amount sensor being arranged corresponding to the spring compression amount sensing head and sensing.

4. The presser foot assembly of claim 1 wherein, One end of the connecting rod is provided with a strip-shaped groove, the convex shaft is provided through the strip-shaped groove and can be pivoted and slid in the strip-shaped groove.

5. The presser foot assembly of claim 1 wherein, The swing component further includes a shaft rod, one end of the shaft rod being fixed to the column and the other end being provided through the presser rod.

6. The presser foot assembly of claim 1 wherein, The actuating mechanism further includes an actuating force transmission assembly arranged between the actuator and the output shaft, the actuator transmitting power to the output shaft through the actuating force transmission assembly.

7. The presser foot assembly of claim 6 wherein, The actuating force transmission assembly is a speed reduction gear set.

8. The presser foot assembly of the sewing machine according to claim 1, wherein The control module further includes a control unit, a motor driving unit, a main shaft driving unit, a setting / operation unit and a display unit, the motor driving unit being electrically connected to the actuator, the main shaft driving unit, the setting / operation unit and the display unit being electrically connected to the control unit.

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