JPS6349265Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to a sewing machine equipped with a presser foot control device.

(Problems to be Solved by Prior Art and Invention) Conventionally, in this type of sewing machine, for example, when the presser foot is placed in an upward position and the foot pedal is operated, the presser foot is lowered. At the same time, a signal to drive the sewing machine motor is output, and based on each signal, the presser foot starts lowering and the sewing machine motor rotates at high speed. There is something.

However, in this conventional sewing machine, after the presser foot starts descending, it takes a certain amount of time to press the workpiece cloth, so the sewing machine motor rotates at high speed without pressing the workpiece cloth. The needle, feed dog, etc. will be activated. In this case, the fabric may lift as the needle moves up and down, and the hook may not be able to catch the loop supported by the needle, or the upper thread may fall out of the eye of the needle.
A problem arises in that a seam is not formed at the start of sewing.

(Objective of the Invention) This invention has been made in consideration of the above circumstances, and its objective is to provide a sewing machine equipped with a presser foot control device that can reliably form stitches at the start of sewing.

(Means for Solving the Problems) In order to solve the above problems, this invention includes a needle that is moved up and down across the work cloth support surface as the main shaft of the sewing machine rotates, and the work cloth a seam forming device that forms seams on a work cloth on a support surface;
A feed dog that is operated in synchronization with the seam forming device and applies feed to the work cloth, and a feed dog that is movable up and down on the sewing machine frame so that it can be raised and lowered between an upper inactive position and a lower working position. a presser foot that presses the workpiece cloth toward the feed dog when supported and placed in an operating position; a presser foot driving means that raises and lowers the presser foot; and a drive that rotationally drives the main shaft of the sewing machine. As the motor and foot pedal are depressed,
A first output means for outputting a presser foot lowering signal and a speed command signal according to the amount of depression thereof; and a low speed speed command different from the speed command signal output from the first output means. The second output signal
output means, and when the foot pedal is operated with the presser foot placed in the inactive position, the first output means outputs an output for a predetermined time longer than the time required for lowering the presser foot. The low speed command signal output from the second output means is enabled and output to the drive motor, and the presser foot lowering signal is enabled to drive the presser foot. and control means for validating the speed command signal output from the first output means after the predetermined time has elapsed.

(Function) Therefore, when the foot pedal is operated with the presser foot placed in the upper inactive position, the presser foot is lowered based on the output of the presser foot lowering signal, and the presser foot is lowered. The drive motor is rotated at a low speed based on the low speed command signal outputted from the second output means, and the sewing machine is operated at a low speed for a predetermined time period longer than the time required for the sewing machine to descend. When the predetermined time period has elapsed, the drive motor is rotated based on a speed command signal outputted from the first output means in accordance with the amount of depression of the foot pedal, and the sewing machine is operated.

(Example) An example embodying this invention will be described below with reference to the drawings. As shown in FIG. 2, a sewing machine main shaft 2 is rotatably supported on an arm portion 1a of a sewing machine frame 1, and a driven pulley 2 is attached to the sewing machine main shaft 2.
A is attached. On the other hand, a drive motor 3 is mounted on the lower surface of the bed portion 1b of the sewing machine frame 1, and its power is transmitted to the sewing machine main shaft 2 via a drive pulley 3a, a belt 4, a driven pulley 2a, etc.

A needle bar 6 having a needle 5 at its lower end is supported by the arm portion 1a so as to be movable up and down, and the needle 5 moves up and down across the work cloth support surface 7 of the bed portion 1b as the sewing machine main shaft 2 rotates. be done. A stitch is formed on the work cloth on the work cloth support surface 7 by the cooperation of the needle 5 and a thread loop catcher (not shown) in the bed portion 1b. Further, a well-known sewing machine is provided on the bed portion 1b facing the needle 5 in synchronization with the rotation of the main shaft 2 of the sewing machine.
A feed dog (not shown) to which a feed motion is applied is provided, and feed is applied to the work cloth based on the operation of the feed dog.

Further, as shown in FIGS. 2 and 3, a presser bar 9 is attached to the arm portion 1a on the cloth feeding side of the needle bar 6.
is supported so as to be movable up and down, and is urged to move downward by a spring (not shown). A cloth presser foot 10 is attached to the lower end of this presser bar 9, and a presser bar holder 11 is attached approximately to the middle portion.

On the other hand, an electromagnetic solenoid 12 (see FIG. 3) constituting a driving means for vertically moving the presser foot 10 is disposed inside the arm portion 1a, and the plunger 12a is connected to a connecting rod 13, a link 14, and a short shaft. operating rod 15a, long operating rod 15b, lever 1
6. It is operatively connected to a connecting rod 17 and a rotating lever 18 in sequence, and one end of the rotating lever 18 is disposed below the protrusion of the needle bar holder 11. When the electromagnetic solenoid 12 is excited, each member 13, 14, 15a, 15b, 16-
18 is moved or rotated in the direction of the arrow in FIG. As a result, through the engagement between the rotary lever 18 and the presser bar holder 11, the presser foot 10 is raised together with the presser bar 11 against the biasing force of the spring, and the presser foot 10 is moved upwardly. placed in the working position.

On the other hand, when the electromagnetic solenoid 12 is demagnetized, the presser bar 9 is moved downward by the biasing force of the spring, the presser foot 10 is placed in the lower working position, and the work cloth is pressed against the feed dog. Ru. Also,
Each of the members 18, 17, 15b, 15a, 1
4, 13 and the plunger 12a are returned or rotated in the opposite direction of the arrow in FIG.

As shown in FIG. 2, a control box 20 mounted on the lower side of the drive motor 3 includes a control means 2.
1st class is built in. In addition, as shown in Fig. 5, a pedal depression amount detector consisting of a Hall element, etc.
The PV outputs a speed command signal (voltage) to the control means 21 according to the amount of depression of the foot pedal 23 shown in FIG. Furthermore, the foot pedal 23
When the switch is depressed, the switch SW shown in Figure 4 is pressed.
is turned on, and based on this, a presser foot lowering signal is input to the electromagnetic solenoid 12, and the electromagnetic solenoid 12 is demagnetized. The pedal depression amount detector PV and the switch SW constitute a first output means.

When the foot pedal 23 is operated with the presser foot 10 placed in the upper inactive position,
The second output means 25 outputs to the control means 21 a low-speed speed command signal different from the speed command signal output from the first output means. At this time, the control means 21 invalidates the speed command signal from the first output means for a time longer than the time required for lowering the presser foot 10, and also disables the low speed command signal from the second output means 25. The speed command signal is validated and output to the drive motor 3 via the motor drive circuit 26.

Therefore, the electrical configuration of the control means 21 and the second output means 25 will be explained in detail with reference to FIGS. 4 to 6.

When the foot pedal 23 is not depressed, the switch SW shown in FIG. 4 is held in the OFF state, and in this state, the resistors R1,
Transistor Tr1 is turned on via buffer circuit B1 and resistor R2. Therefore, the coil SL1 of the electromagnetic solenoid 12 is energized to excite the electromagnetic solenoid 12, and the presser foot 10 is placed in an upper non-active position.

In addition, the timer circuit T
is held inactive and transistor Tr2 is
It is turned off. Therefore, relay coil RL1
is not energized and its normally open contact RL1b
(see FIG. 5) is held open. Note that the timer circuit T is included in the control means 21. Further, the transistor Tr3 is turned on via the buffer circuit B2 and the resistor R3. Therefore, coil RL2 of the relay is energized,
Its normally open contact RL2b (see FIG. 5) is closed. At this time, the potential at the connection point a shown in FIG. 5 is at the "L" level.

In this state, when the foot pedal 23 is depressed, the switch SW is closed and the timer circuit T outputs an "L" level signal for a predetermined time "t" shown in FIG. Therefore, the transistor Tr2 is kept in the OFF state until the time "t" has elapsed. Further, with the closing of the switch SW, the transistor Tr1 is
OFF, the electromagnetic solenoid 12 is demagnetized, and the presser foot 10 begins to descend.

Further, as the switch SW is closed, the transistor Tr3 is turned off, and the normally open contact RL2b of the relay shown in FIG. 5 is opened. On the other hand, when the foot pedal 23 is depressed, a speed command signal is output from the pedal depression amount detector PV, and the output level increases according to the depression amount.
Since the normally open contact RL1b of the relay is opened based on the operation of the timer circuit T, the speed command signal is invalidated. Therefore, the potential at the connection point a rises to a potential preset by the resistor R4 and the variable resistor R5 (see FIG. 6), and based on that potential, the drive motor 3 is driven to rotate at a low speed of about 230 spm. and the sewing machine is operated at low speed.
Note that the second output means 25 is constituted by this resistor R4, variable resistor R5, and the like.

Then, while the drive motor 3 is rotating at a low speed, the presser foot 10 finishes lowering and is placed in a lower inactive position, and the workpiece cloth is pressed against the feed dog. Therefore, it is possible to reliably feed the work cloth at the start of sewing, and it is possible to prevent the possibility that a seam will not be formed at the start of sewing.

Thereafter, when the predetermined time "t" set by the timer circuit T has elapsed, the timer circuit T
outputs an "H" level signal. Therefore, the transistor Tr2 is turned on and the normally open contact of the relay is turned on.
RL1b is closed. At this time, the speed command signal of the pedal depression amount detector PV is activated, and the potential of the connection point a increases accordingly, and the drive motor 3 is activated.
The sewing machine is operated at high speed by rotating at a high speed of about 5000 spm.

In addition, in this embodiment, in order to invalidate the speed command signal based on the depression of the foot pedal 23 when the presser foot 10 is lowered, and to activate a low-speed speed command signal different from the speed command signal, , a timer circuit T, etc. was provided, but a needle position detection device was provided in place of the timer circuit T, and the sewing machine was It is also possible to operate the sewing machine at a high speed and lower the presser foot 10 during that time, and to operate the sewing machine at a high speed after the presser foot 10 has been lowered.

(Effects of the invention) As detailed above, this invention can automatically control the vertical movement of the presser foot, and also allows the sewing machine to operate at high speed before the presser foot is placed in the working position at the start of sewing. As a result, when sewing starts, the fabric may lift up as the needle moves up and down, and the hook may not be able to catch the loop supported by the needle, or the upper thread may fall out of the eye of the needle. This provides an excellent effect in that the seams can be reliably formed without falling out or bunching up.

[Brief explanation of drawings]

Fig. 1 is a block circuit diagram of a sewing machine embodying this invention, Fig. 2 is a front view of the sewing machine, Fig. 3 is a perspective view showing the presser foot mechanism, Figs. 4 and 5 are electrical circuit diagrams, Figure 6 is a time chart. In the figure, 2 is the main shaft of the sewing machine, 3 is a drive motor, 5 is a needle, 7 is a work cloth support surface, 10 is a presser foot, 12 is an electromagnetic solenoid constituting a drive means,
21 is a control means, 23 is a foot pedal, 25 is a second output means, SW is a switch, and PV is a pedal depression amount detector (the SW and PV constitute the first output means).

Claims (1)

[Claims for Utility Model Registration] Includes a needle 5 that is moved up and down across a work cloth support surface 7 as the main shaft 2 of the sewing machine rotates, and forms stitches on the work cloth on the work cloth support surface 7. a sewing machine, comprising: a seam forming device; a feed dog that is operated in synchronization with the seam forming device and feeds the work cloth; a presser foot 10 that is vertically movably supported by a frame and presses the workpiece cloth toward the feed dog when placed in an operating position; and a presser foot drive means 12 that moves the presser foot 10 up and down. , a drive motor 3 that rotationally drives the sewing machine main shaft 2;
and a first output means SW that outputs a presser foot lowering signal as the foot pedal 23 is depressed, and outputs a speed command signal in accordance with the amount of depression.
PV, the first output means SW, a second output means 25 that outputs a low-speed speed command signal different from the speed command signal output from the PV, and the presser foot 10 are arranged in a non-active position. When the foot pedal 23 is operated in this state, the speed command signal output from the first output means SW and PV is invalidated for a predetermined time longer than the time required for lowering the presser foot 10, and Second output means 25
The low-speed speed command signal output from the presser foot driving means 1 is activated and outputted to the drive motor 3, and the presser foot lowering signal is activated and the presser foot drive means 1 is activated.
2 and a control means 21 for validating the speed command signal output from the first output means SW, PV after the predetermined time has elapsed.