CN217298213U - Automatic control device for presser foot of sewing machine - Google Patents

Abstract

An automatic control device for presser foot of sewing machine comprises an input module, a control module and an operating mechanism which are integrated into a whole; during sewing, the presser foot in the operating mechanism is pressed on the cloth and simultaneously the cloth thickness sensing head of the operating mechanism is used for matching with the cloth thickness variation sensed by the cloth thickness sensor in a linkage manner, and outputting a signal to the control module to control the force input module to actuate, and the force input module outputs pressure fluid with proper pressure to the pressure cylinder of the operating mechanism so as to automatically adjust the acting force applied to the presser foot rod by the spring, so that the acting force applied to the cloth by the presser foot connected with the presser foot rod is kept constant, and the stitch length is kept constant. Therefore, the utility model provides a presser foot automatic control device of sewing machine can improve because of the shortcoming of the seam gauge front and back inconsistent that the cloth thickening caused.

Description

Automatic control device for presser foot of sewing machine

Technical Field

The utility model relates to a sewing machine's technical field especially relates to sewing machine's presser foot automatic control device, can control pushing down or lifting up of presser foot laborsavingly at the sewing in-process to meet the cloth of different thickness at the presser foot and adjust the presser foot at any time automatically and apply in the presser foot automatic control mechanism of the effort of cloth.

Background

As shown in fig. 1 and 2, the conventional sewing machine includes a machine body a having a base a1 and an L-shaped arm a2 coupled above the base a1, the arm a2 and the base a1 being provided with transmission mechanisms coupled to each other, respectively, wherein a sewing platform a11, a needle plate a12 and a feed dog B formed on the sewing platform a11 are provided on the left side of the base a 1; the left side of the machine arm A2 is provided with a presser foot device C and a needle bar mechanism and other related components; during sewing, the cloth D is continuously fed between the bottom surface of the presser foot C1 of the presser foot device C and the upper side of the needle plate a12, and is driven forward by the cloth feeding teeth B in a reciprocating manner to perform sewing.

As shown in fig. 2 and 3, the conventional presser foot device C of the sewing machine has a presser foot C1, and the presser foot C1 tightly presses the bottom surface of the presser foot C1 against the fixing area of the working surface by the compression force of the spring C2 of the device. The elastic pressing force acts on the cloth D to clamp the cloth D between the bottom surface of the presser C1 and the working surface of the needle plate a12, and to generate a certain degree of friction. The feed dog B, which is movably arranged in the fixed region of the working surface, is an element which is driven by the drive mechanism to generate a counterclockwise circular motion with an approximately elliptical motion trajectory, i.e., the feed dog B is driven to lift the tooth surface B1 relative to the working surface, moves to the left side of the drawing surface for a horizontal displacement, then sinks to the working surface again, and repeats the cycle. Through the repeated and cyclic movement of the cloth feeding tooth B, when the tooth surface B1 of the cloth feeding tooth B is higher than the working surface, the cloth D and the presser foot C1 are lifted, and the tooth surface B1 of the cloth feeding tooth B replaces the working surface to clamp the cloth D between the bottom surfaces of the presser foot C1; then, the cloth feeding tooth B moves leftwards by a horizontal displacement following the cloth feeding tooth B, and at the moment, because the friction force between the tooth surface B1 of the cloth feeding tooth B and the cloth D is greater than the friction force between the cloth D and the bottom surface of the presser foot C1, the cloth D can move horizontally by a displacement following the cloth feeding tooth B, and the sewing cloth feeding work is completed in this way.

However, the cloth D is displaced horizontally in a leftward step motion according to the operating frequency of the machine due to the continuous operation of the machine, but the displacement amount does not completely coincide with the horizontal displacement amount of the feed dog B, but rather, the displacement amount has a certain sliding rate, which depends on the magnitude of the force applied to the presser bar C3 of the presser device C, because the magnitude of the force affects the magnitude of the frictional force between the cloth D and the bottom surface of the presser C1 and the magnitude of the frictional force between the cloth D and the tooth surface B1 of the feed dog B. When the friction force between the cloth D and the tooth surface B1 of the cloth feeding tooth B is larger than the friction force between the cloth D and the bottom surface of the presser foot C1, the sliding rate is smaller, and the horizontal displacement of the cloth D is closer to that of the cloth feeding tooth B, and vice versa.

As described above, in the conventional sewing machine, the magnitude of the biasing force applied to the presser foot C1 can be adjusted by manually adjusting the lever E to adjust the compression amount of the compression spring C2 provided on the presser foot lever C3. However, during operation of the sewing machine, the thickness of the cloth D may vary randomly, and it is often the case in practice that the thickness of the cloth D may increase by 2 times or 4 times (for example, sewing after folding the cloth by an unspecified number of layers). When the thickness of the cloth D is increased, since the presser foot C1 needs to be lifted upwards by more movement to accommodate the thicker cloth D between the bottom surface of the presser foot C1 and the tooth surface B1 of the cloth feeding tooth B, it can be understood that the upward movement of the position of the presser foot C compresses more compression amount of the spring C2 via the presser bar C3, so that the force applied to the cloth D becomes larger, and the larger force applied will cause the friction between the bottom surface of the presser foot C1 and the cloth D and the friction between the tooth surface B1 of the cloth feeding tooth B and the cloth D to change; the friction force change can change the sliding rate, and the sliding rate change can make the horizontal displacement of cloth D when the cloth thickness is unchanged different from the horizontal displacement of cloth D when the cloth thickness becomes thick, so will cause the stitch gauge of the stitch to be inconsistent, and then influence the finished product pleasing to the eye.

In addition to the above disadvantages, referring back to fig. 1, the conventional presser foot device C needs to operate an operating mechanism F to lift the presser foot C1 to release the cloth D from being fastened or to put down the presser foot C1 to fasten the cloth D, so as to put the cloth D on or take down the cloth D from the working surface. The operating mechanism F conventionally applies an external force to the first link F1 to pull the first link F1 downward and then pull the second link F2, so that the third link F3 drives the rotating shaft F4 to rotate counterclockwise, the fourth link F5 fixed to the rotating shaft F5 also rotates counterclockwise, and further pulls the fifth link F6 upward, the fifth link F6 pulls the presser bar C3 upward while pulling the presser bar C3 upward, since the presser foot C1 is fixed to the presser bar C3, the presser foot C1 is also pulled upward to release the pressing force on the cloth D when the presser bar C3 is pulled up; when the applied force is released, the presser foot C1 returns to its original state. The conventional operation of applying force to the presser foot C1 may be manual, pneumatic or electromagnetic, and any operation force is based on the original mechanical structure with additional auxiliary or force applying actuating units, which has the disadvantages of complicated mechanism transmission chain, space occupation, high cost of force applying actuating units, and loud noise.

In order to solve the above drawbacks of the prior art, the inventor of the present application proposes taiwan application No. 110133248, which provides a presser foot device of a sewing machine, wherein a control module is electrically connected to an actuating mechanism, a sensing unit of the control module senses the displacement change of the presser foot, and after a signal of the change of the presser foot displacement is fed to the control module, an elastic force action mechanism for applying force to the presser foot is controlled to lift or lower upwards, so that the force applied to the cloth by the presser foot is kept constant, thereby achieving the consistency of the stitch length of the sewing thread.

In addition, another taiwan application No. 110214770 of the present inventor provides an entry force modularized presser foot control device of a sewing machine, which comprises an entry force module, an operating mechanism and a control module integrated into a whole; during sewing, the presser foot in the operating mechanism is pressed on the cloth and simultaneously the sensing mechanism senses the variation of the thickness of the cloth in a linkage manner, and outputs a signal to the control module to control the action of the force input motor so as to change the acting force of the spring applied to the presser foot rod, so that the acting force of the presser foot connected with the presser foot rod applied to the cloth is kept constant, and the stitch length of the stitch is kept constant. The control module can be used for inputting system operation parameters to control the main shaft motor of the sewing machine to actuate to carry out sewing; the control module can also display relevant data such as system operation parameters and the like to a display unit.

SUMMERY OF THE UTILITY MODEL

The utility model discloses an one of them aim at provides an integration type solution to the shortcoming that above-mentioned traditional sewing machine exists to income power module collocation control module integrates to operating device in order to replace traditional operating device, and assist and lift up with the return operation with the steerable presser foot of electronic control system, and the effort that the control was exerted on the presser foot is in order to keep the relatively invariable state, has advantages such as small, simplify mechanical structure, low cost, operation laborsaving, noise reduction, borrows this to improve as above inconsistent shortcoming around the stitch seam gauge needle that causes because of the cloth thickening.

The utility model provides a presser foot automatic control device of sewing machine can include: the entry module includes: a pressure source for supplying a pressure fluid; the directional valve is connected with the pressure source and used for receiving the pressure fluid of the pressure source and controlling the flow direction of the pressure fluid; and a switch valve connected with the directional valve for controlling the pressure fluid to pass or not pass; the control module is electrically connected with the force input module and used for controlling the direction valve to guide the flowing direction of the pressure fluid and the opening or closing of the switch valve; and an operating mechanism provided in the body of the sewing machine and connected to the force input module, the operating mechanism including: the pressure cylinder is connected to the direction valve and the switch valve of the input module, a piston capable of moving in a reciprocating mode is arranged inside the pressure cylinder, and the piston is connected with the connecting shaft; a spring top cylinder connected to the connecting shaft, the spring top cylinder having an inner space; a spring disposed in the inner space of the spring top cylinder; the upper end of the pressure foot rod penetrates through the inner space of the spring top cylinder, and the spring acts between the pressure foot rod and the upper end of the inner space of the spring top cylinder; the presser foot is arranged at the lower end of the presser foot rod; the cloth thickness sensor is electrically connected with the control module; and a cloth thickness sensing head connected to the presser bar and axially corresponding to the cloth thickness sensor at a predetermined interval, wherein, in the sewing process, when the bottom surface of the presser bar is pressed on a thick cloth, the presser bar is pushed up or down according to the cloth thickness, so as to change the displacement generated by the distance of the cloth thickness sensing head relative to the cloth thickness sensor, at the moment, the cloth thickness sensor outputs a first signal of the displacement to the control module, the control module outputs a second signal to a force input module driving unit of the control module according to the first signal after calculation by an algorithm of a computer program, so as to drive the force input module to actuate, further control the opening or closing of the directional valve and the switch valve, and enable the pressure fluid of the pressure source to flow into the pressure cylinder to push the piston to ascend or descend to interlock and ascend or descend the spring top cylinder, thereby changing the compression amount of the spring and the acting force on the presser foot rod, and keeping the acting force applied to the cloth by the presser foot at a set value. The utility model discloses an operating device who goes into power module, control module and integration as an organic whole keeps invariable and makes the stitch gauge needle of suture keep unanimous except that the effort that makes the presser foot apply at the cloth, still has mechanical structure simply, does not account for space, with low costs, the laborsaving, the noise of operation is little, the installation advantage such as easy.

Preferably, the entry module may further include: a first pressure regulating valve connected between the pressure source and the directional valve for regulating the pressure from the pressure source to the directional valve; and a second pressure regulating valve connecting the directional valve and the on-off valve for regulating the pressure from the directional valve to the on-off valve. Therefore, the user can adjust the air pressure applied to the pressure cylinder of the operating mechanism according to the actual situation, thereby adjusting the pressure applied by the presser foot to the cloth.

Preferably, the control module may include: the control unit is electrically connected with the cloth thickness sensor; the spindle motor driving unit is electrically connected with the control unit and a spindle motor; the force input module driving unit is electrically connected with the control unit and the force input module; a setting operation unit electrically connected with the control unit; the display unit is electrically connected with the control unit, wherein the setting operation unit can be used for inputting system operation parameters to the control unit, and the control unit controls the spindle motor to actuate through the spindle motor driving unit according to the input system operation parameters; the control unit controls the action of the force input module through the force input module driving unit according to the first signal output by the cloth thickness sensor; and the control unit outputs corresponding data to the display unit according to the system operation parameters input by the setting operation unit and the first signal output by the cloth thickness sensor.

Preferably, a lower stop retaining ring can be arranged at the lower part of the inner space of the spring top cylinder, an upper stop retaining ring can be arranged at the upper part of the presser bar, and after the spring top cylinder moves upwards for a certain distance, the presser foot is lifted upwards by the lower stop retaining ring abutting against the upper stop retaining ring, so that the presser foot is separated from the pressing and fixing of the cloth.

Preferably, the pressure cylinder may be a pneumatic cylinder and the pressure source is a pressurized gas supply.

Preferably, the piston divides the interior of the cylinder into an upper air chamber and a lower air chamber, the cylinder has a first air port communicating with the lower air chamber and a second air port communicating with the upper air chamber, the first air port is connected with the directional valve, the second air port is connected with the on-off valve, wherein when the control module controls the directional valve and the on-off valve, the pressure source enters the upper air chamber through the first pressure regulating valve, the directional valve, the second pressure regulating valve and the on-off valve to push the piston to descend, and discharges the air in the lower air chamber to the atmosphere through the directional valve, the pressure foot is applied with a force to descend to press and fix the cloth on a sewing platform, wherein when the control module controls the directional valve and the on-off valve, the pressure source enters the lower air chamber through the first pressure regulating valve and the directional valve to push the piston to ascend, and when the presser foot meets the change of the thickness of the cloth under the working state of contacting the cloth, the cloth thickness sensor outputs the first signal to the control module to control the switch valve to be closed, so that the pressure source enters the pressure fluid into the lower air chamber through the first pressure regulating valve and the direction valve to push the piston to rise, and the gas in the upper air chamber is blocked by the switch valve to counterbalance the pressure of the lower air chamber, thereby slightly lifting the presser foot.

Drawings

FIG. 1 is a perspective view showing a structure of a conventional sewing machine;

FIG. 2 is a front view schematically showing the structure of a conventional sewing machine;

FIG. 3 is a schematic view of a partial plane showing an elliptical path motion of a cloth feeding tooth of a conventional sewing machine in cooperation with a presser foot to drive a cloth to move;

FIG. 4 is a schematic perspective view showing the automatic presser foot control device of the sewing machine of the present invention;

fig. 5 is a schematic plan view showing the automatic presser foot control device of the sewing machine of the present invention;

FIG. 6 is a block diagram showing the control mode of the control module according to the present invention;

fig. 7 is a schematic plan sectional view showing the force applied by the force input module of the present invention to make the presser foot press the cloth on the sewing platform;

fig. 8 is a schematic view showing the force applied by the force input module of the present invention to control the spring top cylinder to move upward, so that the presser foot is separated from the cloth; and

fig. 9 is a schematic view showing a control state when the presser foot of the present invention encounters a thick cloth.

Description of the reference numerals

& lt & ltThe utility model

1: body

11: base

111: sewing platform

112 needle plate

12 machine arm

2, feed the tooth

21 tooth flank

3: control module

31 control unit

32 spindle motor driving unit

33 drive unit of input module

34 setting operation unit

35 spindle motor

36 display unit

4 operating mechanism

41 spring top cylinder

411 inner space

412 lower stop buckle

42: spring

43 presser foot bar

431 upper stop snap ring

44 presser foot

45, a cloth thickness sensor 46, a cloth thickness sensing head 47, a pressure cylinder 471, a first air port 472, a second air port 473, an upper air chamber 474, a lower air chamber 475, a piston 476, a connecting shaft 5, an input module 51, a pressure source 52, a first pressure regulating valve 53, a directional valve 54, a second pressure regulating valve 55, a switch valve 56, atmosphere 6, cloth DS and a distance

[ Prior Art ]

A is a body

A1 base

A2 arm

A11 sewing platform A12 needle plate

B, cloth feeding teeth

B1 tooth surface

C, presser foot device

C1 presser foot

C2 spring

C3 presser foot bar

D, cloth

E, manually adjusting rod

F operating mechanism

F1 first Link

F2 second connecting rod

F3 third connecting rod

F4 rotating shaft

F5 fourth connecting rod

F6 fifth connecting rod

Detailed Description

In order to facilitate understanding of the present invention, the present invention will be described in detail with reference to the accompanying drawings and examples. Some, but not all embodiments of the inventions are shown in the drawings. The invention may be embodied in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete. All other embodiments, which can be obtained by a person skilled in the art without any great effort based on the embodiments of the present invention, belong to the protection scope of the present invention.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

As shown in fig. 4 and 5, the sewing machine of the present invention includes a machine body 1, the machine body 1 has a base 11 and an L-shaped arm 12 combined above the base, the left side of the base 11 has a sewing platform 111 and a needle plate 112 and a feeding tooth 2 (as shown in fig. 5) formed on the sewing platform 111, and a presser foot device included in an operating mechanism 4 described later is correspondingly arranged above the needle plate 112; as shown in fig. 5, the bottom surface of the presser foot 44 of the presser foot device is pressed and fixed on the cloth 6, the feed dog 2 is arranged inside the base 11, and an elliptical motion mechanism (not shown) drives the feed dog 2 to move in an elliptical track, so that the tooth surface 21 on the feed dog 2 rises from the hole of the needle plate 112 to above the upper surface of the needle plate 112 or sinks below the upper surface of the needle plate 112, that is, the feed dog 2 moves in a step shape relative to the presser foot 44, and thus, the motion is rapidly and repeatedly performed to convey the cloth 6 to the left side shown in the drawing.

The utility model provides a presser foot automatic control device of sewing machine, including a control module 3 (as shown in figure 6), an entry module 5 and an operating device 4. Wherein, the input module 5 may be disposed on the body 1 (for example, the side of the arm 12) of the sewing machine, as shown in fig. 5, the input module 5 may include: a pressure source 51, a first pressure regulating valve 52, a directional valve 53, a second pressure regulating valve 54, and an on-off valve 55. The pressure source 51 is preferably a pressure gas supply device such as an air compressor for supplying compressed air with sufficient pressure. The first pressure regulating valve 52 and the second pressure regulating valve 54 are both elements for regulating the pressure of the compressed air passing through, and both the first pressure regulating valve 52 and the second pressure regulating valve 54 can be manually regulated or digitally electronically regulated. The directional valve 53 is an element for controlling the flow direction of the compressed air. The on-off valve 55 is an element for controlling whether to let the compressed air pass or not. Wherein, the pressure source 51 is connected with the first pressure regulating valve 52, the first pressure regulating valve 52 is connected with the direction valve 53, the direction valve 53 is connected with the second pressure regulating valve 54, the second pressure regulating valve 54 is connected with the switch valve 55, and the switch valve 55 is connected with the pressure cylinder 47 of the operating mechanism 4; the directional valve 53 is basically a four-way valve, so that in addition to two ports connecting the first and second pressure regulating valves 52 and 54, respectively, the other port is connected to the atmosphere 56, and the other port is also connected to the cylinder 47 of the operating mechanism 4.

As shown in fig. 5 and 7, the operating mechanism 4 is a mechanical structure actually used for sewing the cloth 6, and the operating mechanism 4 is disposed on the machine body 1 and connected to the power module 5; the operating mechanism 4 includes: spring top tube 41, spring 42, presser bar 43, presser foot 44, cloth thickness sensor 45, cloth thickness sensing head 46 and pressure cylinder 47. The spring top tube 41 is a cylindrical body and has an inner space 411. The spring 42 is preferably a compression spring, which is disposed in the interior space 411 of the spring top case 41. The upper end of the presser bar 43 penetrates through the inner space 411 of the spring top cylinder 41 and can move relative to the spring top cylinder 41 in the axial direction, and the upper end and the lower end of the spring 42 respectively act between the presser bar 43 and the upper end of the inner space 411 of the spring top cylinder 41, namely, the spring 42 applies downward acting force to the presser bar 43; preferably, a lower stop ring 412 is disposed at a lower portion of the inner space 411 of the pogo pin 41, and an upper stop ring 431 is disposed at an upper portion of the press pin 43, so that when the pogo pin 41 moves upward to a position, the lower stop ring 412 abuts against the upper stop ring 431 to drive the press pin 43 to move upward. The presser foot 44 is provided at the lower end of the presser foot lever 43, and is a member for pressing and fixing the fabric. The cloth thickness sensor 45 is fixedly provided at the machine body 1, and may be a sensor capable of emitting infrared or laser light to measure the length, however, the cloth thickness sensor type is not limited. The cloth thickness sensing head 46 is a rod member of a cylindrical shape fixedly coupled to the side of the presser bar 43 such that the end of the cloth thickness sensing head 46 axially corresponds to the end of the cloth thickness sensor 45 in the vertical direction when the operating mechanism 4 is installed in the machine body 1, and the cloth thickness sensor 45 and the end of the cloth thickness sensing head 46 are spaced apart from each other by a distance, so that the distance between the end of the cloth thickness sensor 45 and the end of the cloth thickness sensing head 46 can be calculated when infrared rays or laser light emitted from the cloth thickness sensor 45 is projected to the end of the cloth thickness sensing head 46, and the displacement amount can be calculated when the distance is changed. The pressure cylinder 47 is preferably a cylinder, and has a piston 475 (as shown in fig. 7) disposed therein and capable of reciprocating, the piston 475 is connected to a connecting shaft 476, the piston 475 separates the interior of the pressure cylinder 47 into an upper air chamber 473 and a lower air chamber 474, the pressure cylinder 47 is provided with a first air port 471 communicated with the lower air chamber 474 and a second air port 472 communicated with the upper air chamber 473, the present invention connects the first air port 471 to the directional valve 53 of the input module 5, and connects the second air port 472 to the on-off valve 55 of the input module 5, so that the operation module 4 can be driven by the input module 5.

As shown in fig. 6, the control module 3 is a software and hardware device for controlling the input module 5 to drive the operating mechanism 4 to actuate, and includes: a control unit 31, a spindle motor driving unit 32, a force input module driving unit 33, a setting operation unit 34, and a display unit 36. The control unit 31 may be a unit formed by a Central Processing Unit (CPU) and a memory, and is electrically connected to the cloth thickness sensor 45 of the operation module 4. The spindle motor driving unit 32 is a driving circuit for controlling whether the spindle motor 35 of the sewing machine is operated or not, and is electrically connected to the control unit 31. The spindle motor 35 is electrically connected to the spindle motor driving unit 32 to drive the elliptical motion mechanism of the sewing machine to drive the cloth feeding teeth 2 to generate the step motion, and to drive the related link mechanism to drive the sewing needle to move up and down to sew the cloth. The force input module driving unit 33 is a driving circuit for controlling the force input module 5 to be activated or not, and is electrically connected to the control unit 31. The input module 5 is electrically connected to the input module driving unit 33. The setting operation unit 34 is an interface device for inputting data, and is electrically connected to the control unit 31 for providing input of related system operation parameters (such as stitch gauge, spring compression amount, motor speed, …, etc.) during sewing, that is, the system operation parameters are input to the control unit 31 through the setting operation unit 34, and the control unit 31 controls the operation of the spindle motor 35 through the spindle motor driving unit 32 according to the input system operation parameters. The display unit 36 may be an LCD display electrically connected to the control unit 31 for displaying data input through the setting operation unit 34 and displaying related information generated during the sewing process.

The operation mode when the utility model is used for sewing is explained as follows: as shown in fig. 7, during sewing, when the bottom surface of the presser foot 44 is pressed against the fabric 6, the presser foot lever 43 is pushed up or down according to the thickness of the fabric 6, so as to change the distance DS between the fabric thickness sensing head 46 and the fabric thickness sensor 45 and generate a displacement, at this time, the fabric thickness sensor 45 outputs a first signal of the displacement to the control unit 31 of the control module 3, the control unit 31 calculates according to the first signal by an algorithm of a computer program and then outputs a second signal to the force input module driving unit 33 to drive the force input module 5 to actuate, further change the compression amount of the spring 42 and the acting force of the spring 42 on the presser foot lever 43, so that the acting force exerted on the fabric 6 by the presser foot 44 maintains a set value, and simultaneously, relevant information is displayed on the display unit 36.

In more detail, as shown in fig. 7, in an initial state of the sewing process, a user operates the control module 3 to drive the force input module 5 to actuate, so that the pressure source 51 inputs pressure fluid into the upper air chamber 473 of the pressure cylinder 47 through the first pressure regulating valve 52, the directional valve 53, the second pressure regulating valve 54 and the switch valve 55 to push the piston 475 to descend, and exhausts the air in the lower air chamber 474 to the atmosphere 56 through the directional valve 53 (as shown in the flow path arrow direction of the force input module 5 in fig. 7), in this state, the connecting shaft connected to the piston 475 drives the spring top cylinder 41 to descend and move downwards together with the presser bar 43 and the presser foot 44 until the bottom surface of the presser foot 44 touches the cloth 6, and the spring top cylinder 41 starts to compress the spring 42 to increase the force 476 applied by the presser foot 44 to the cloth 6; accordingly, the amount of compression of the spring 42 can be set, the operator can set the desired amount of compression through the setting operation unit 34 of the control module 3, and the control unit 31 adjusts the pressure values of the first and second pressure regulating valves 52 and 54 through the inlet module driving unit 33 to control the pressure of the pressure gas entering the upper air chamber 473, thereby compressing the spring 42 to the target amount.

As shown in fig. 8, when the cloth is to be released from the presser foot 44 during sewing, the pressure source 51 drives the force input module 5 to move the pressure fluid into the lower air chamber 474 of the pressure cylinder 47 through the first pressure regulating valve 52 and the directional valve 53 to push the piston 475 to ascend, and the air in the upper air chamber 473 is exhausted to the atmosphere 56 through the switch valve 55, the second pressure regulating valve 54 and the directional valve 53 (as shown in the direction of the flow path arrow of the force input module 5 in fig. 8), in this state, the connecting shaft 476 connected to the piston 475 drives the spring top cylinder 41 to ascend until the lower stopper retaining ring 412 arranged on the spring top cylinder 41 touches the upper stopper retaining ring 431 arranged on the presser bar 43 to pull up the presser bar 43 continuously, so that the presser foot 44 is separated from the cloth 6, and at this time, the cloth 6 can be moved out of the sewing platform.

As shown in fig. 9, when the machine is operated steadily and continuously, the cloth 6 also moves steadily in a predetermined direction, when the presser foot 44 encounters a change in the thickness of the cloth (for example, when sewing a multi-layer folded cloth) in a working state contacting the cloth 6, the presser foot 44 moves upward through the thickened cloth 6, and the presser bar 43 moves upward, and the cloth thickness sensing head 46 approaches the cloth thickness sensor 45, and at this time, the distance DS between the cloth thickness sensor 45 and the cloth thickness sensing head 46 is measured by the cloth thickness sensor 45, and then a signal is fed to the control unit 31 of the control module 3, the control unit 31 immediately sends a correction signal to the inlet module driving unit 33, and the inlet module driving unit 33 controls the on-off valve 55 of the inlet module 5 to close, and the pressure source 51 makes a pressure fluid enter the lower air chamber 474 of the pressure cylinder 47 through the first pressure regulating valve 52 and the direction valve 53 to push the piston 475 to rise, at this time, since the gas in the upper air chamber 473 is blocked by the switch valve 55 and cannot be discharged to counterbalance the pressure in the lower air chamber 474 (in the direction of the flow path arrow of the force input module 5 shown in fig. 9), the presser foot 44 can be lifted up only a little to match the increase in the thickness of the cloth 6, so that the fixing force applied to the cloth 6 by the presser foot 44 can be stabilized at the target set value, and thus the stitch pitch can be prevented from being changed due to the change in the compression amount of the spring 42.

The above-mentioned embodiments only represent the preferred embodiments of the present invention, and the description thereof is more specific and detailed, but not to be construed as limiting the scope of the invention. It should be noted that, for those skilled in the art, without departing from the spirit of the present invention, several changes and modifications can be made, which are within the scope of the present invention.

Claims (6)

1. An automatic presser foot control device for a sewing machine, comprising:

the entry module includes:

a pressure source for supplying a pressure fluid;

the directional valve is connected with the pressure source and used for receiving the pressure fluid of the pressure source and controlling the flow direction of the pressure fluid; and

the switching valve is connected with the directional valve and is used for controlling the pressure fluid to pass or not pass;

the control module is electrically connected with the force input module and used for controlling the directional valve to guide the flow direction of the pressure fluid and the opening or closing of the switch valve; and

an operating mechanism disposed on a body of the sewing machine and connected to the input module, the operating mechanism including:

the pressure cylinder is connected to the directional valve and the switch valve of the input module, a piston capable of moving in a reciprocating mode is arranged inside the pressure cylinder, and the piston is connected with a connecting shaft;

a spring top cylinder connected to the connecting shaft, the spring top cylinder having an inner space; a spring provided in the inner space of the spring top cylinder;

a presser bar, the upper end of which is inserted into the inner space of the spring top cylinder and causes the spring to act between the presser bar and the upper end of the inner space of the spring top cylinder;

the presser foot is arranged at the lower end of the presser foot rod;

the cloth thickness sensor is electrically connected with the control module; and

a cloth thickness sensing head connected to the presser bar and axially corresponding to the cloth thickness sensor at a predetermined interval,

wherein, in the sewing process, when the bottom surface of the presser foot is pressed on a thick cloth, the presser foot rod is pushed upwards or downwards according to the thickness of the cloth, so as to change the displacement generated by the distance between the cloth thickness sensing head and the cloth thickness sensor, at the moment, the cloth thickness sensor outputs a first signal of the displacement to the control module, the control module outputs a second signal to an input module driving unit of the control module to drive the input module to actuate according to the first signal after being calculated by an algorithm of a computer program, so as to control the actuating direction of the directional valve and the opening or closing of the switch valve, and the pressure fluid of the pressure source flows into the pressure cylinder to push the piston to ascend or descend to link the spring ejection cylinder to ascend or descend, and further changing the compression amount of the spring and the acting force on the presser foot rod, so that the acting force applied to the cloth by the presser foot keeps a set value.

2. The presser foot automatic control device of sewing machine as claimed in claim 1, wherein said entry force module further comprises:

a first pressure regulating valve connecting the pressure source and the directional valve for regulating the pressure from the pressure source to the directional valve; and

and the second pressure regulating valve is connected with the directional valve and the switch valve and used for regulating the pressure from the directional valve to the switch valve.

3. The presser foot automatic control device of sewing machine according to claim 2, wherein said control module comprises:

the control unit is electrically connected with the cloth thickness sensor;

the spindle motor driving unit is electrically connected with the control unit and the spindle motor;

the force input module driving unit is electrically connected with the control unit and the force input module;

the setting operation unit is electrically connected with the control unit; and

a display unit electrically connected to the control unit,

wherein the content of the first and second substances,

the setting operation unit can be used for inputting system operation parameters to the control unit, and the control unit controls the spindle motor to actuate through the spindle motor driving unit according to the input system operation parameters;

the control unit controls the input module to actuate through the input module driving unit according to the first signal output by the cloth thickness sensor; and

and the control unit outputs corresponding data to the display unit according to the system operation parameters input by the setting operation unit and the first signal output by the cloth thickness sensor.

4. The automatic presser foot control device according to claim 1, wherein a lower stopper ring is provided at a lower portion of the inner space of the pogo pin, an upper stopper ring is provided at an upper portion of the presser bar, and when the pogo pin has moved upward by a distance, the presser foot is lifted upward by abutting the lower stopper ring against the upper stopper ring, and the presser foot is released from pressing the cloth.

5. An automatic presser foot control device for a sewing machine according to claim 2, wherein said pressure cylinder is an air cylinder and said pressure source is a pressurized air supply device.

6. An automatic presser foot control device for a sewing machine according to claim 5, wherein said piston divides the inside of said cylinder into an upper air chamber and a lower air chamber, said cylinder has a first port communicating with said lower air chamber and a second port communicating with said upper air chamber, said first port is connected to said directional valve, said second port is connected to said on-off valve,

wherein when the control module controls the directional valve and the switch valve to make the pressure source enter the upper air chamber through the first pressure regulating valve, the directional valve, the second pressure regulating valve and the switch valve to push the piston to descend and discharge the gas in the lower air chamber to the atmosphere through the directional valve, the presser foot is applied with a force to descend to press and fix the cloth on the sewing platform,

wherein when the control module controls the directional valve and the on-off valve to make the pressure source enter the pressure fluid into the lower air chamber via the first pressure regulating valve and the directional valve to push the piston to ascend and discharge the gas in the upper air chamber to the atmosphere via the on-off valve, the second pressure regulating valve and the directional valve, the presser foot is acted by force to ascend and separate from the cloth, and

when the presser foot is in contact with the cloth and the thickness of the cloth changes under the working state of contacting the cloth, the cloth thickness sensor outputs the first signal to the control module to control the switch valve to be closed, so that the pressure source enables the pressure fluid to enter the lower air chamber through the first pressure regulating valve and the directional valve to push the piston to ascend, and the gas in the upper air chamber is blocked by the switch valve to counterbalance the pressure of the lower air chamber, and further the presser foot is lifted slightly.

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