JPS6040876B2 - Sewing machine presser foot lifting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a presser foot lifting device for a sewing machine, and more particularly to a presser foot lifting device that uses power to raise a presser foot to an arbitrary position corresponding to the amount of displacement of a knee-lifting lever.

Conventionally, this type of power-operated presser foot lifting device could only move the presser foot up and down to a preset position, but could not control the position so that it could move and stop at any desired position at any time.

As a result, there is a sense of discomfort because there is no sense of unity between the movement of the pig and the vertical movement of the presser foot as in the case of mechanical methods, and the presser foot rises more than necessary, regardless of the thickness of the fabric.
It is difficult to align the fabric, resulting in poor operability, and the sewing efficiency cannot be improved. This invention enables the presser foot to move and stop at any position corresponding to a signal generated in relation to the amount of displacement of the ratchet lever linked to the movement of the knee (a signal corresponding to the operating position of the knee raiser lever). In addition to solving the above-mentioned drawbacks of the follower, it also improves the safety of the sewing machine by electrically prohibiting movement of the presser foot by operating the knee-lifting lever while the sewing machine is operating, thereby preventing the occurrence of sewing defects. The purpose is to enhance sexuality.

Embodiments of the present invention will be described below with reference to the drawings.

The sewing machine in this embodiment is a lockstitch sewing machine equipped with a thread cutting device, and in particular, the
The sewing machine described in the specification of No. 61579 (Japanese Unexamined Patent Publication No. 57-175390) is equipped with a known microcomputer (microcomputer) having a storage device that stores in advance a plurality of modes consisting of a plurality of different processes. The number of stitches for each sewing process in the selected mode can be set appropriately for each process, and the information stored in the storage device related to the operation of the manual operation device (depression of the pedal) is read out to perform the sewing of one process. This is a sewing machine that is controlled to automatically stop sewing when the set number of stitches for that process is completed, and then to execute the next process of sewing when the pedal is pressed. , the sewing machine is programmed in advance so that it stops with the sewing machine needle stuck in the fabric at the end of each intermediate process other than the final process.The machine configuration is shown in Figure 1. The presser foot 1 is supported, the presser foot 2 is fixed to the lower end of the presser foot 1, the presser foot 3 is fixed to the middle of the presser foot 1, and the presser foot 1 is attached to the upper part of the presser foot 1 and rotated. A known presser foot pressure adjustment screw 4 is screwed into the machine frame and supported so as to be movable up and down along the presser bar 1, and a coil spring 5 is compressed and disposed between the adjustment screw 4 and the presser foot holder 3. It is the composition.

FIG. 2 shows the main parts of the presser foot lifting device, which is located below the sewing machine bed (not shown). 6. It is supported by the lever shaft so that it can be freely extended within a predetermined range around the horizontal axis along the cloth feeding direction, and is always subject to the force of an elastic body in a clockwise direction, facing the worker. A known pig-lifting lever 7 operated by the worker's knee is fixed downward to the extended front end, and a fan-shaped gear 8 is fixed at the rear.

9 is a small gear that meshes with gear 8.

101. A motor as a drive device capable of forward and reverse rotation.

11' is a threaded shaft having a male thread formed on its upper portion, and is rotatably supported on the machine frame via sprockets 12, 13 and a timing belt 14.

Reference numeral 15 denotes a movable body having a female thread that engages with the male thread of the threaded ratchet 11, and a rack 17 parallel to the axis of the threaded shaft 11 is fixed to the tip of a guide pin 16 that projects in the radial direction.

18 is the 4th gear that meshes with the rack 17.

Reference numeral 19 denotes a guide plate fixed to the machine frame, and has an elongated hole 20 along the axis of the screw shaft 11 in which the guide pin 16 engages so as to prevent rotation of the movable body 15.

Reference numeral 21 denotes a known push-up rod, which is generally supported on a machine frame such as the bottom of an oil pan so as to be able to move up and down.

This push-up twill 21 can be lowered by its own weight until the upper part 21a hits the upper bowl of the machine frame, and the lower end always hangs downward from the lower surface of the rock frame, and the movable body 1
5. The upper end surface 15a of Reference numeral 22 denotes a presser foot lifting lever, and a pin 22a provided at one end is inserted into the uppermost hole 3a of the presser bar holder 3, and is linked to the lifting of the lifting birch 21 via an appropriate linkage mechanism (not shown). It rotates clockwise as shown in Figure 1 about a shaft 23 fixed to the machine frame.
Further, the push-up camphor 21 moves downward and rotates counterclockwise.

Regarding the electric circuit, reference numerals 24 and 25 indicate half-circuit type variable resistors, and the resistor 25 receives a power supply voltage and generates a voltage higher than that of the resistor 24.

26, 27, and 28 are variable resistors (potention motors), the variable resistor 26 generates different voltages (presser foot lifting signal) corresponding to the rotation angle position of the small gear 9, and the variable resistor 27 generates a different voltage (presser foot lifting signal). Different voltages (position signals) are generated corresponding to the rotational angular position of the small gear 18, and although the variable resistor 28 is not shown, it generates a voltage (correction signal) corresponding to the rotational angular position of the dial that can be manually operated. do.

Reference numerals 29, 30, and 31 are analog switches whose inputs and outputs are connected by receiving a low level L signal at a control terminal CO.

The differential increase circuit 32 increases the difference between the input voltages A and B. If the increase rate is 8, the output voltage C is 8.(A
-B). The comparison voltage generation circuit 33 receives the power supply voltage and generates different voltages D and E (D>E). The motor control circuit 34 compares the voltage of C with the voltages of D and E and generates outputs of F and G as follows. Motor drive circuit 3
5 rotates the motor 10 in the clockwise direction (arrow) in FIG. 2 when the output F from the motor control circuit 35 is positive, and rotates the motor 0 in the anticlockwise direction when the output G is positive. It rotates and acts to stop the motor 10 when the outputs F and G are L.

In this embodiment, the sewing machine control circuit 36 is for controlling the sewing mechanism and other attached mechanisms of the sewing machine according to a predetermined program in relation to the selected sewing mode, and outputs a start signal in relation to the depression of the pedal. It also generates a presser signal Y in connection with the end of the valley intermediate process in each mode, and further generates a command signal Z for operating the wiper or thread trimming device in connection with the end of the final process in each mode. Occur. Comparator 37 outputs a day signal when the positive input voltage becomes higher than the negative input voltage.
The selection circuit 38 is for determining which analog switch is to be made conductive depending on the operating state of the sewing machine, and when the start signal x is generated, all outputs from terminals A, C and C are set to 1, and after the start signal x is generated, If the presser signal Y is generated before the command signal Z is generated, the output of only terminal A is set to L, and when the presser signal Y is generated after the command signal Z is generated and before the start signal x is generated. In this case, the output of only the terminal port is set to L, and furthermore, when the day signal is generated in the comparator 37, the output of only the terminal C is set to L even if the output of terminal A or port is in the L state. Note that R' is a resistor suspended between the analog switch 29 and the differential multiplication circuit 32. This invention has the above configuration, and its operation will be explained next.

In FIGS. 1 and 2, when the motor 10 rotates clockwise, the screw shaft 11 rotates in the same direction as the motor 0 via the timing belt 14. Since this movement is prevented by the playback, the moving body 15 moves upward due to the above-mentioned rotation of the screw shaft 11.

Conversely, when the motor 10 rotates counterclockwise, the movable body 15 moves downward. This movable body 15 is always lowered to a predetermined position, and in this state, the presser bar 1 is lowered by the elastic force of the coil spring 5 to a position where the presser foot 2 contacts the top surface of the bed and then stopped. When the movable body 15 rises from this state, the push-up bar 21 is pushed upward, and in conjunction with this, the presser foot lift lever 22 is moved upward from the shaft 23.
Turn clockwise around the center and pull up the presser foot 1 through the presser foot holder 3 against the coil, so that the presser foot 2
rises a distance proportional to the amount of rise of the moving body 15. Therefore, by controlling the amount of rotation of the motor 10, the height at which the presser foot 2 rises from the top surface of the bed can be changed as appropriate. Mobile object 1
5 rises, a voltage corresponding to the rising level is generated in the variable resistor 27.

Further, when the knee raising lever 7 is rotated in all directions, a voltage corresponding to the rotation position is generated in the variable resistor 26. Therefore, the rotation of the motor 10 is controlled as follows. For example, when a mode suitable for a sewing pattern consisting of a plurality of sewing processes is selected, the number of stitches for each process is set, and the pedal is depressed, a start signal Z is output from the sewing machine control circuit 36, so that the analog switches 29, 30 , 31 are rendered non-conductive, and the A input of the rhombic multiplier circuit 32 receives the negative power supply voltage.

As a result, the C output of the differential amplification circuit 32 becomes lower than the E output voltage of the comparison voltage generation circuit 33, and the G output becomes positive, so that the motor 10 rotates counterclockwise. This motor 10
As the movable body 15 descends due to the rotation of the presser bar 1, the output voltage of the variable resistor 27 gradually decreases.
When the voltages of A and B inputs become equal, C becomes zero volts. Furthermore, since the relationship between the inputs of the motor control circuit 34 becomes D>C>E, the F and F of the motor control circuit 34 become
The G output becomes L' and the rotation of the motor 10 stops. Therefore, when the pedal is depressed after the cloth is layered on the upper surface of the bed, the presser bar 1 is lowered by the acting force of the coil and the counterfeit 5, and the cloth presser foot 2 presses the cloth. Further, the sewing machine is started at approximately the same time as the cloth is pressed by the presser foot 2 to form a stitch. When the previously set number of stitches are formed, the sewing machine automatically stops with the sewing machine needle sticking into the fabric at the final needle drop point, and the presser foot lifting signal Y is generated from the sewing machine control circuit 36. Since this occurs after the start signal X is generated and before the command signal Z is generated, the analog switch 29 is activated in relation to the generation of the presser foot lifting signal Y. As a result,
Since the relationship between both inputs of the differential increase circuit 32 is A>B, and the input of the motor control circuit 34 is C>D, the motor 0 will rotate clockwise until the above relationship becomes A=B. The presser foot 2 moves upward, allowing the cloth to rotate.Then, if the pedal is pressed again from this state, the above-mentioned action is repeated.When the set number of stitches are formed in the final process, a command signal Z is sent. occurs and the thread trimming device, wiper etc. are operated, and then the presser signal Y is generated, so in this case, the analog switch 30 becomes conductive and the differential increasing circuit 32
The voltage of the variable resistor 25 is received at the A input of the variable resistor 25.

As a result, the presser foot 2 rises in the same manner as described above, but since the output voltage of the variable resistor 25 is higher than the output voltage of the variable resistor 24, the presser foot is lower in the final process than in other intermediate processes. Leg 2 rises high from the top of the bed. Next, when the pig raising lever 7 is pressed and rotated counterclockwise, the output voltage of the variable resistor 26 gradually increases in proportion to the amount of displacement, and when it becomes higher than the negative input of the comparator 37, the analog switch 31 conducts, brush stroke increasing circuit 3
The output voltage of the variable resistor 26 is received at the A input of No. 2.

Therefore, in this case, the amount of rise of the presser foot 2 is the amount that the knee lift lever 7
When the knee-lifting lever 7 is rotated to the maximum, the presser foot 2 will rise to the highest position, and when the knee-lifting lever 7 is returned to its initial position, the presser foot 2 will descend again to raise the cloth. Press against the top of the bed. Note that FIG. 4 is a diagram showing the relationship between the displacement amount of the knee-lifting lever 7 and the lifting amount of the presser foot 2. By appropriately operating the variable resistor 28, the output voltage of the variable resistor 26 can be changed. changes, so the bias Q in the above diagram changes.

According to this, even if the lifting lever 7 is operated to the same position, the lifting position of the presser foot 2 changes. In this embodiment, a motor 0 capable of forward and reverse rotation is used as the drive device, but the push-up rod 21 may be moved up and down by a linear motor, or an air or hydraulic cylinder or an electromagnetic solenoid may be used to move the push-up rod 21 up and down. 21 may be moved up and down.

For example, in the case of a cylinder, the movable element 42 of the cylinder 41 is controlled via a five-way, three-position solenoid valve 40 as shown in FIG. That is, the variable resistor 27 of this embodiment is arranged in relation to the movable element 42, and when the relationship between both inputs of the differential expansion circuit 32 is A>B, the solenoid 43 is energized to move the movable element 42 upward. When A<B, the solenoid 44 is energized to push down the movable element 42, and when A=B, both solenoids 43 and 44 are demagnetized to stop the movable element 42 in the illustrated state. Alternatively, the movable member 42 of the cylinder 41 that is moved up and down via a five-way, two-position solenoid valve 45 or an electromagnetic solenoid (not shown) as shown in FIG. It may also be regulated by a biased cam 46 that can be rotated in relation to information related to the amount of rise of the presser foot. Furthermore, although this embodiment shows an analog control method, it is possible to install an A/D comparator after each variable resistor to convert it into a digital signal, or to use an encoder that generates a pulse signal in place of the variable resistor. The motor may be controlled by comparing these digital signals or by processing them with a microcomputer.

Furthermore, in this embodiment, after the differential multiplication circuit 32, the comparison voltage generation circuit 33 and the differential multiplication circuit 32 are used to convert to digital control, but the output of the differential multiplication circuit 32 is directly connected to the motor. You can do it like this.

Further, in this embodiment, the comparator 37 detects the movement of the knee-up lever 7 from its initial position, but the movement of the knee-up lever 7 may be detected by other known detection means. Furthermore, the push-up device shown in FIG. 2 may be incorporated inside the sewing machine frame,
These may be attached as a unit to the table of a sewing machine, and the present device may be applied to sewing machines other than lockstitch, or to various sewing machines that are not equipped with a thread cutting device or a device for storing sewing modes.

As described above, according to the present invention, the movement of the presser foot can be controlled in real time to a position corresponding to the operation position in synchronization with the operation of the knee-lifting lever, so that the presser foot lifting operation does not feel strange and is excellent in operability. Moreover, since the presser foot can be moved to any desired position at any time by operating the knee-lifting lever, the sewing efficiency is improved.

In addition, during sewing work on the sewing machine, the presser foot will not rise even if the knee-lift lever is operated by mistake, so the presser foot will not rise unexpectedly and the fabric will shift, and the sewing machine will not move as intended. It also has the effect of forming neat seams.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of the presser foot device, Fig. 2 is a perspective view of the presser foot lifting device, Fig. 3 is a block diagram of the electric circuit, and Fig. 4 shows the operating position of the knee-lifting lever and the raised position of the presser foot. Diagrams 5 and 6 showing the relationship are other embodiments. DESCRIPTION OF SYMBOLS 1... Presser bar, 2... Cloth presser foot, 10... Motor as a drive device, 26... Variable resistor constituting a signal emitting device during manual operation, 27, 32, 33, 34 ,3
5... A variable resistor, a differential amplifier circuit, a comparison voltage generation circuit, a motor control circuit, and a motor drive circuit that constitute the control device of this embodiment. 1 figure, 2 figures, 4 figures, 3 figures, 6 figures

Claims (1)

[Claims] 1 Presser foot 2 is supported vertically on the machine frame and normally receives elastic force to press the workpiece against the top surface of the bed, and outputs signal B corresponding to the raised position of the presser foot from the top surface of the bed. a first signal generating device 27, which normally receives an elastic force on one side and is arranged so that the knee can be operated in the opposite direction against the elastic force so as to raise the presser foot; A second signal generator 26 that outputs a signal corresponding to the operating position; a drive unit 10 that reciprocates to move the presser foot up and down; The control circuits 32, 33, 34, and 35 control the operation of the drive devices so that the outputs match, so that the presser foot is controlled to move in conjunction with the operation of the knee-lifting lever to a position corresponding to the operation position. The presser foot lifting device of the sewing machine includes a sewing machine control circuit 36 that generates a start signal X for starting the sewing machine and a command signal Z for operating a thread cutting device that cuts sewing thread, a second signal generating device, and a control circuit. A switch 31 placed between the circuit and the
In response to the output of the sewing machine control circuit, the above switch is turned on and off.
This presser foot lifting device for a sewing machine is characterized in that a selection circuit 38 for making the switch non-conductive makes the switch non-conductive after a start signal is generated and makes the switch conductive after a command signal is generated.