JPS5943196B2 - Automatic control device for electric sewing machines - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic control device for an electric sewing machine, and more particularly to an automatic control device that stops a sewing needle at a fixed position such as top dead center or bottom dead center when sewing a zigzag pattern, for example. .

2. Description of the Related Art Conventionally, electric sewing machines using an electric motor as a drive source have been put into practical use.

In such an electric sewing machine, for example, a zigzag pattern is sewn using a cam and a cam follower member that abuts the periphery of the cam. This kind of pattern sewing is
This is generally done continuously, and the operator de-energizes the motor when the desired number of patterns have been sewn. Therefore, if the timing of stopping the electric motor is incorrect, an undesirable pattern will be formed, which is undesirable. Therefore, the main object of the present invention is to provide an automatic control device for an electric sewing machine that dynamically stops the sewing needle blade at a predetermined position in response to sewing one pattern during pattern sewing. It is.
To summarize, this invention is an electric sewing machine that can sew a zigzag pattern, and one pattern cycle is completed.
This is an automatic control device for an electric sewing machine that detects when the sewing needle reaches a predetermined position such as top dead center (or bottom dead center), and applies reverse phase braking to the drive motor in response to this detection. . The above objects and other objects and features of the invention will become more apparent from the following detailed description with reference to the drawings. FIG. 1 is a schematic illustration of an electric sewing machine that forms the background of this invention and in which this invention is implemented.

Specifically, a sewing machine arm AM is formed on the upper surface of the sewing machine bed BS, and a sewing machine arm AM that houses various mechanisms therein is provided, and a driving electric motor M is provided below the sewing machine belt BS or outside the arm AM. A belt B1 is hung on a pulley MP provided on the rotating shaft of the electric motor M,
This driving force by belt B1 is transmitted to belt B2 at a certain speed ratio via an intervening pulley. This belt B2 is further placed around a pulley SP formed on the main shaft SH, which serves as a drive source for the various mechanisms described above, and rotationally drives this pulley SP and therefore the main shaft SH. The main shaft SH is connected to the needle bar NR via a crank CR, and drives the needle bar NR in the vertical direction according to its rotation.

Further, a sewing needle NDL is fitted into the lower end of the needle bar NR, and a lower thread (lower thread bobbin) wound around an inner hook and a bobbin is disposed below the sewing machine bed BS opposite to the position of the sewing needle NDL. Therefore, this sewing needle NDL sews the upper thread and bobbin thread near its bottom dead center, and then returns to its top dead center,
Such operations are repeated according to the rotation of the main shaft SH. Here, a pattern cam ZC is further rotatably connected to the main shaft SH via a connecting portion WM including a worm and a worm gear. This pattern cam ZC has irregularities corresponding to the pattern to be sewn on its outer peripheral edge. A cam following member (not shown) is provided so as to be able to freely swing and come into contact with the periphery of the pattern cam ZC, and this cam following member is further connected to the needle bar NR. Therefore, as the pattern cam ZC rotates, the sewing needle NDL swings laterally (horizontally) in accordance with the unevenness formed on the outer peripheral edge of the cam ZC to sew the pattern. The pattern cam ZC
The unevenness corresponding to the pattern shape formed on the outer peripheral edge of the cam ZC is formed all around the periphery so that one pattern cycle is completed by one revolution of the pattern cam ZC. Also, although not shown,
Of course, a controller is provided in connection with the first driving electric motor M, for example, having a pedal and adjusting the speed of the electric motor M in accordance with the depression of the pedal.

Further, in this embodiment, the sewing needle NDL is controlled to stop near the top dead center every time the one pattern cycle ends, and a predetermined position of the pulley SP of the main shaft SH is set for the purpose of detecting the position of the sewing needle NDL. A magnet MGl is fixedly provided.

Further, when this magnet MGl is displaced in accordance with the rotation of the pulley SP, when it reaches a position corresponding to the top dead center position of the sewing needle NDL, this magnet MGl in the sewing machine arm AM
A reed switch LSl is fixedly provided at a position opposite to l. That is, the magnet MG provided on the pulley SP
sewing needle N by reed switch LSl opposite to l.
Detects that DL has reached top dead center. Further, in order to detect the completion of one cycle of the pattern sewing, a magnet MG2 is fixedly provided at a predetermined position, for example, on the outer peripheral edge of the upper surface of the pattern cam ZC. The predetermined position is preferably determined at the beginning or end of a pattern cycle. A reed switch LS2 is fixedly provided at a predetermined position in the sewing machine arm AM opposite to the magnet MG2. That is, the completion of one cycle of pattern stitching is detected by the magnet MG2 provided on the pattern cam ZC and the reed switch LS2 provided oppositely. In this invention, such two detection outputs are processed in an AND manner to deenergize the electric motor M and perform anti-phase braking.
It should be noted that in FIG. 1, only essential parts related to the present invention are shown, and other parts are omitted.

FIG. 2 is an electrical circuit diagram showing a preferred embodiment of the invention.

In terms of configuration, this embodiment shows a case where a DC motor is used, and the plug PL is connected to, for example, a commercial power source to supply power to the motor M. A full-wave rectifier diode D1 is provided between one end and the other end of the plug PL, and a thyristor SCR is provided at both ends of the full-wave rectifier diode D1.
A series circuit of the motor M and the motor M including the field coil (not shown) is inserted. Furthermore, a series circuit of a semi-fixed resistor r1 and a variable resistor R3 is inserted between both ends of the full-wave rectifier diode D1 to apply a set voltage (gate signal) to the gate electrode of the thyristor SCR. Further, across both ends of this full-wave rectifier diode D1, in parallel with the series circuit,
A series circuit of a resistor R2 and a semi-fixed resistor R4 (semi-fixed to correct variations in each component) is connected. These resistors rl and R3 provide normal (NOrmal)
) mode of operation, and resistors R2 and R4 provide a relatively low set voltage during Pattern mode operation. The slider of the variable resistor R3 (
(slides in response to depression of the pedal of the controller)
is connected to the NOrmal mode contact N of the mode changeover switch SWl2, and the Patte of this switch SWl2 is
The rn mode contact P is connected to the connection point between the resistors R2 and R4. Therefore, each of the set voltages is different from the high speed operation mode (NOrmal) or the low speed operation mode (Patte).
rn) by this switch SWl2 and applied to the gate electrode of the thyristor SCR via the diode D2. A parallel circuit including a bias resistor R5 and a protective capacitor C1 (to prevent malfunction when a pulsed voltage component is applied) is inserted between the gate electrode and cathode electrode of this thyristor SCR. Further, at both ends of the plug PL, there are provided a mode changeover switch SWll which is manually switched in conjunction with the mode changeover switch SWl2, a switch SW2 which is connected to the pedal of the controller, the reed switch LSl and the relay R1. A series circuit and the reed switch LS2
and a series circuit of relay R2 are inserted.

One normally open contact Rlal of the relay R1 is connected in parallel to the reed switch LSl, and the other normally open contact Rlal is connected in parallel to the reed switch LSl.
la2 is connected in parallel to the semi-fixed resistor R4.

In addition, two normally closed contacts R1bl and Rl of relay R1
b2 is inserted between the motor M (armature) and the cathode of the thyristor SCR, and between the motor M (armature) and the negative side of the full-wave rectifier diode D1, and the other normally closed contact Rlb3 is inserted between the contact x of the controller switch SW2 and the reed switch LS2. The remaining two normally open contacts Rla3 and Rla4 of the relay R1 are connected between the connection point of the motor M and the normally closed contact R1bl and the negative side of the full-wave rectifier diode D1, respectively. Electric motor M and the normally closed contact Rlb
2 and the cathode side of the thyristor SCR. Further, said relay R2 includes two normally open contacts R2al and R2a2, and one normally open contact R2a2.
2al is connected between contact 0 and contact X of the switch SW2, and the remaining normally closed contact R2a2 is connected in parallel to the reed switch LS2. A series circuit of a delay resistor R6 and a capacitor C2 is connected in parallel to both ends of this relay R2, and with the above configuration, its operation will be explained below with reference to Figures 1 and 2. . NOrma
In the case of the I mode, first, the mode changeover switches SWll and SWl2 are sequentially switched to the contact N side by manual operation.

Then, the plug PL is connected to a commercial power source. Next, gradually depress the controller pedal (h in the figure). Therefore, the set voltage V1 generated by the voltage divider circuit of the semi-fixed resistor rl for high speed setting and the variable resistor R3 according to the pedal
is applied to the gate electrode of the thyristor SCR via the changeover switch SWl2} and the diode D2. Therefore,
A gate current flows through this thyristor SCR, and the thyristor SCR is turned on. Therefore, the electric motor M starts rotating and a back electromotive voltage V2 is generated. The back electromotive force V2 of the motor M is compared with the set voltage V1 (1-V2
) becomes the trigger voltage of the thyristor SCR, and the motor M reaches a constant speed. That is, if back electromotive voltage V2>setting voltage V1, thyristor SCR will not turn on. Therefore, the electric motor M operates such that the back electromotive force V2 is constant, and the rotation speed is controlled according to the depression of the pedal (and therefore the value of the variable resistor R3). In this way, normal operations, such as lock stitching, for example, are achieved. Pat
In the case of the tern mode, first, the mode changeover switches SWll and SW12 are manually switched to the contact P side, and the plug PL is connected to the commercial power source.

Therefore, the set voltage 1 applied to the gate electrode of the thyristor SCR is given a divided voltage (relatively low) by the resistors R2 and R4. Therefore, the conduction angle of the thyristor SCR becomes small, and the electric motor M rotates at a predetermined low speed. Let us now assume that one pattern cycle has not yet finished.

First, the user depresses the pedal of the controller to start the sewing machine, and in response, the switch SW2 is switched to the contact Y side. Therefore, relay R1 is not energized, its normally open contacts R1a1 to Rla4 remain open, and normally closed contact R1
bl and Rlb2 remain closed. Therefore, resistance R2
The divided voltage of
rotates. Therefore, the pattern cam ZC rotates and pattern stitching is accomplished. At this time, the sewing needle NDL reaches near the top dead center and the reed switch LSl is closed, but since the switch SW2 has been switched to the Y side in response to the pedal depression, the relay R1 is not energized. . Therefore, pattern sewing continues at this time, and eventually this pattern cam ZC
Earth magnet MG2 faces reed switch LS2. Now, consider the case when one pattern cycle is completed.

As described above, when pattern sewing is performed and magnet MG2 faces reed switch LS2 at the end of the pattern cycle, reed switch LS2 is turned on. Therefore, relay R2 is energized and its two normally open contacts R2al, R
2a2 is closed. Therefore, controller switch SW2 is short-circuited, and this relay R2 is self-held.
At the same time, capacitor C2 for off-delay begins to be charged via resistor R6. Then, when the electric sewing machine continues to rotate at a low speed and the sewing needle NDL reaches near the top dead center, the magnet MGl of the pulley SP faces the reed switch LSl, and the reed switch LSl is turned on.

At this time, since relay R2 is energized at the end of one pattern cycle, the remaining relay R1 is energized, and the normally open contact R
1al to Rla4 are closed, normally closed contacts R1Bl, Rlb
2 is developed. Therefore, the reed switch LSl is self-held by the normally open contact Rlal, and the normally open contact Rla2 connected in parallel with the semi-fixed resistor R4 is closed. Therefore, the relatively low set voltage 1 applied via the changeover switch SWl2 and the diode D2 is cut off, and the thyristor SCR is turned off. Furthermore, normally closed contact Rlb
1 and Rlb2 are opened, and at the same time the normally open contact Rla3
Since Rla4 is closed, the polarity of the residual back electromotive voltage V2 generated when the motor M is rotating by inertia (by turning off the thyristor SCR) is reversed.

Therefore, the differential voltage (V1-V2) becomes (0-(-V2)) even though the set voltage V1 is zero, and a positive gate signal is applied to the gate electrode of the thyristor SCR. Therefore, the thyristor SCR is turned on again, causing the electric motor M to rotate. however,
At this time, the conduction polarity of the motor M is determined by each of the relay contacts Rl.
Since the directions are reversed by trigram a3, Rla4 and R1Bl, Rlb2, the electric motor M will now rotate in the opposite direction to the direction in which it has been rotating due to inertia, and the rotation due to inertia will suddenly increase. Slowed down. Accordingly, the residual back electromotive force V2 caused by the motor M suddenly decreases, the thyristor SCR is turned off, and the motor M and thus the sewing needle NDL are stopped. When the pedal is released, switch SW2 moves from contact point Y to contact point X, but during this movement, power to reed switch LSL is cut off, relay R2 is deenergized, and relay R1 is deenergized. will also be blocked.

However, as mentioned above, since capacitor C2 is charged, this relay R2 is connected to resistor R6 and capacitor C.
It remains energized for a delay time depending on the discharge time constant of 2. Therefore, since the normally open contact R2al of this relay 2 remains held for a while, this switch SW2
The reed switch LSl continues to be energized without being affected by the interruption of the circuit due to the movement of the contact. Therefore, even if the pedal of this controller is pressed once and then immediately released, the reed switches LS1 and LS2 continue to be energized, and the motor M and therefore the main shaft S are continuously energized.
H rotates at low speed and stops at a fixed position. As described above, according to this embodiment, when sewing a pattern, it is detected that one pattern cycle is completed and the sewing needle NDL has reached the top dead center (or a predetermined position), and the main circuit of the electric motor M is cut off. At the same time, since anti-phase braking is applied by the residual back electromotive force of the rotation due to inertia, the electric motor M and therefore the sewing needle NDL
In an instant, the pattern cam ZC rotates approximately once and then is reliably stopped.

Therefore, when sewing patterns, for example, there is no need to take into account the inertia of the electric motor and sewing machine in order to keep the sewing needle in a fixed position, and pattern sewing can be performed at higher speeds, resulting in improved workability and sewing torque. improves. If the controller pedal is once depressed and immediately released, the reed switches LS1 and LS2 are continuously energized by the action of the off delay circuit, so that the sewing needle (that is, the rotation of the main shaft)
stops at a fixed position.

Therefore, it is very convenient in the event of an accident or when changing the pattern. Furthermore, after the sewing needle stops at the fixed position, the sewing needle's position detection circuit (reed switch LSL circuit and magnet MGl circuit)
etc.), so that even if someone dies and turns the flywheel by hand, the electric motor M can be safely used without the risk of suddenly starting to rotate.

FIG. 3 is an electrical circuit diagram showing another preferred embodiment of the invention.

In terms of construction, this embodiment differs from the embodiment shown in FIG. 2 in that a series-wound commutator motor is used as the drive motor M. In the following, only the different parts will be shown in detail, and the explanation of other similar parts will be omitted. Due to the configuration, plug P
L is connected to a commercial power source, for example, and supplies power to the electric motor M.

A series circuit of a thyristor SCR and a motor M including field coils F1 and F2 is inserted between one end and the other end of the plug PL. Furthermore, a series circuit of a semi-fixed resistor rl and a variable resistor R3, and a rectifying diode D3 are inserted at both ends of the plug PL to apply a set voltage to the gate electrode of the thyristor SCR. A series circuit of a resistor R2 and a semi-fixed resistor R4 is connected in parallel between the connecting point of the semi-fixed resistor r1 and the variable resistor R3 and the connecting point of the variable resistor R3 and the diode D3. One normally open contact R1al of the relay R1 is connected in parallel to the reed switch LSl, and the other normally open contact Rla
2 is connected in parallel to the semi-fixed resistor R4. Further, two normally closed contacts R1bl and Rlb2 of relay R1 are inserted between one field winding F1 and the armature and the other open field winding F2 and the armature, respectively. moreover,
One normally open contact Rla3 of this relay R1 connects the normally closed contact R1bl and the armature connection point to the normally closed contact R1bl.
It is inserted between lb2 and the connection point of field winding F2. The remaining normally open contact Rla4 is the normally closed contact R
1bl and the connection point of field winding F1, and the normally closed contact R
It is inserted between lb2 and the armature connection point. Due to this configuration, its operation is similar to that of the embodiment shown in FIG. 2, and detailed explanation thereof will be omitted.

In the above embodiment, reverse phase braking was performed by reversing the polarity of the armature of the motor, but this can also be achieved by reversing the polarity of the field winding. can.

It goes without saying that the relay and its contacts may be replaced by semiconductor switching elements that respond to the opening or closing of the reed switch LS, for example. Furthermore, the above-mentioned predetermined position of the sewing needle includes any case other than the top dead center or the bottom dead center, and the magnet for detecting the predetermined position may be provided on any member that operates synchronously with the main shaft.

At this time, it goes without saying that the reed switch must also be provided at its predetermined position so as to face the magnet. It is also pointed out that in addition to using a reed switch and a magnet for this position detection, various methods such as a proximity switch type or a photoelectric type can be applied. Then, turn the mode selector switch to NOrm.
Of course, if the sewing machine is switched to the al side, continuous pattern stitching can also be performed.

As described above, according to the present invention, the sewing needle can be reliably stopped at a predetermined position with a simple configuration and operation, and a more effective electric sewing machine can be obtained.

[Brief explanation of the drawing]

FIG. 1 is an illustrative view of the main parts of an electric sewing machine that forms the background of this invention and in which this invention can be implemented. FIGS. 2 and 3 are electrical circuit diagrams each showing a preferred embodiment of the invention. In the figure, M is a motor,
MP, SP are pulleys, SH is the main shaft, ZC is the pattern cam, N
DL is sewing needle, LSl, LS2 are reed switch, MGl
, MG2 is a magnet, Rl, R2 is a relay, Rlal~Rl
a4, R2a; R2a2 is a normally open contact, Rlbl, Rlb
2, Rlb3 is a normally closed contact, D1 is a full-wave rectifier diode,
SWll and SWl2 are mode change switches, SW2 is an open/close switch linked to the pedal, SCR is a thyristor, and C
1 and C2 indicate a capacitor.

Claims (1)

[Scope of Claims] 1. A power source, an electric motor energized by the power source, a main shaft driven by the electric motor, a patterned cam connected to the main shaft and rotated, the main shaft and An automatic control device for an electric sewing machine including a sewing needle interlocked with the pattern cam, the mode switching means for switching the electric sewing machine between a relatively high speed operation mode and a relatively low speed operation mode; a first control means for controlling the electric motor; a second control means for controlling the electric motor in the relatively low speed operation mode; a first detection means for detecting that the pattern cam has rotated by a predetermined angle; a second means for detecting that the position has been reached, and an output of the first detecting means and a second detecting means in the relative low speed operation mode;
An automatic control device for an electric sewing machine, comprising switching means for disabling the second control means and braking the electric motor in reverse phase in response to an output from the detection means. 2. The automatic control device for an electric sewing machine according to claim 1, wherein the first control means includes speed adjustment means for the DC motor. 3. The automatic control device for an electric sewing machine according to claim 2, wherein the speed adjusting means includes a pedal and a variable resistor interlocked with the pedal. 4. The pedal further includes a switch contact, wherein the pedal is self-retained by depression of the pedal during the relatively low-speed operating mode and released from the self-retention with a delay time consisting of release of the pedal. An automatic control device for an electric sewing machine according to claim 3, characterized in that: 5. The second detection means detects whether or not the sewing needle has reached the predetermined position based on the rotational position of the main shaft or the position of a member that operates synchronously with the main shaft. An automatic control device for an electric sewing machine according to items 1 to 4 of the scope. 6. The second detection means includes a magnetic element substantially fixed to the main shaft or a member that operates in synchronization with the main shaft, and is arranged at a position facing the magnetic element when the sewing needle reaches the predetermined position. 6. An automatic control device for an electric sewing machine according to any one of claims 1 to 5, further comprising a reed switch. 7. The automatic control device for an electric sewing machine according to claim 1, wherein the switching means further disables the position detection means by its operation. 8. The automatic control device for an electric sewing machine according to any one of claims 1 to 7, wherein the switching means is a relay. 9. The automatic control device for an electric sewing machine according to any one of claims 1 to 8, wherein the switching means is a semiconductor element.