JPS6153077B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a driving device for a sewing machine, and more particularly to a sewing machine driving device including a control device for stopping the sewing machine when the sewing machine needle reaches a predetermined position.

Conventional devices of this type consist of a main motor that drives the sewing machine shaft at high speed when the treadle of the sewing machine is pushed forward, and a main motor that drives the sewing machine shaft at low speed until the needle is at a predetermined position when the treadle is released. When the treadle is pushed backward, the auxiliary motor operates again to drive the needle to another predetermined position at a low speed and then stop it. Such conventional devices have the drawback that it takes a long time to stop the sewing machine from high-speed operation at a predetermined position and again to another predetermined position, resulting in a large time loss.

The present invention has been made in order to eliminate such drawbacks, and the purpose of this invention is to perform switching from a predetermined needle stop position to another stop position in conjunction with the treadle operation that stops the needle from high-speed operation to a predetermined stop position. This reduces time loss and increases the operating rate of the sewing machine by operating the thread trimming device while the sewing machine needle is moving from a predetermined position to another predetermined position, and operating the thread removing device at the same time as the sewing machine needle stops at the other predetermined position. The aim is to provide a device that improves the
The brake device is maintained in an energized state for a longer time than the operating time of the thread removing device to safely and reliably perform thread removing.

An embodiment of the present invention shown in the drawings will be described below. In Fig. 1, 1 is a sewing machine table;
2 is a sewing machine body, 3 is a sewing machine needle, 36 is a sewing machine shaft, 4 is a sewing machine pulley fitted to the sewing machine shaft, 5
is a cylindrical metal slip ring for needle position detection fixed to the sewing machine shaft, 6 is an insulating band provided on a part of the circumference of the slip ring, and 7, 8, and 9 are brushes that touch the surface of the slip ring. A sewing machine needle position detector is formed which detects the position of the needle by slidingly contacting the needle and detecting a conductive state. M is a main motor that drives the sewing machine, 13 is a motor section thereof, and 12 is a flywheel fixed to its rotating shaft, which is constantly rotating. 14 is a clutch wheel with friction plates pasted on both sides, 16 is a movable shaft coupled to this clutch wheel, 15 is a movable bearing, 11 is a pulley provided on the movable shaft, and 10 is a link between this pulley and the sewing machine pulley 4. A connecting belt, 17 a clutch lever for driving the movable bearing, 18 a fulcrum thereof,
19 is a yoke pin that connects the clutch lever and the movable bearing; 20 is a spring that applies clockwise rotational force to the clutch lever; and 21 is an operating lever that is connected to the clutch lever by a pin 25 and rotates downward in the figure. When driven, the clutch lever is rotated counterclockwise around the fulcrum 18, but when driven upward in the figure, the clutch lever is rotated counterclockwise around the fulcrum 18.
Only the control lever rotates around . Reference numeral 22 denotes a footboard for controlling the sewing machine, which has a well-known configuration. 23 is a connecting rod that connects the footboard and the lever; 24 is a micro switch that operates when the clutch lever rotates clockwise; 26 is a micro switch that operates when the operating lever 21 independently rotates clockwise; A is an auxiliary motor that drives the sewing machine at low speed, 27 is an output shaft 28 of which is a small pulley fixed to the output shaft, 29 is a DC excitation type brake provided at the opposite end of the output shaft, and 30 is the same as described above. A frame that forms part of the main motor.
Auxiliary motor A is attached to this part. 3
1 is a medium pulley that is rotatably supported on a part of the main motor; 34 is a belt that connects this medium pulley and the small pulley; 35 is a gear that is connected to the support shaft of the medium pulley; 32 is meshed with this gear. A low-speed disk rotatably supported by a bearing 33 also opposes the clutch wheel 14 described above, and when the clutch wheel 14 comes into contact with this disk, the rotation of the auxiliary motor A is transferred to the movable shaft 1.
It is now possible to transmit to 6. In addition, Fig. 2 shows the control circuit, and 40 and 41 are AC power supplies;
45, 46, 47, and 48 are full-wave rectifiers, 49 is a smoothing capacitor, and 24 is a switch controlled by the footboard 22, which is normally closed to the b side and when the footboard 22 is pushed in the A direction, the switch is closed to the a side. It is supposed to be closed.

RA1 is the first relay, RA11 and RA13 are its normally open contacts, and RA12, RA14, and RA15 are the first relays.
This is a switching contact controlled by a relay, which is normally closed on the b side and closed on the a side when the relay is energized. RA2 is the second relay, RA22,
RA23 is a normally open contact, and RA21 is a changeover switch controlled by the second relay, which is normally closed to the b side and closed to the a side when the second relay is energized. RA3 is the third relay, RA31,
RA32 is the normally open contact, 5 is the above-mentioned slip ring, 6 is also the above-mentioned insulating band, 7, 8, 9 are brushes, 51, 54, 57 are NPN transistors, 5
0, 53, 56 are resistors, 52, 55 are capacitors, 29 is an electromagnetic brake, 58 is an electromagnet for driving the thread trimming device, 59 is an electromagnet for driving the thread removing device, 4
2, 43, and 44 are power supplies for auxiliary motors.

Next, the operation of this embodiment will be explained. First step board 2
2 in the direction A, the connecting rod 23 moves downward in FIG.
moves to the left and connects the clutch wheel 14 to the constantly rotating flywheel 12. As a result, the power from the main motor is transmitted to the sewing machine via the pulley 11, belt 10, and sewing machine pulley 4, rotating the sewing machine shaft 36 at high speed. . At this time, the switch 24 operates and closes to the a side, energizing the first relay RA1.
RA11 is closed and the first relay RA1- contact
A needle lower position detection circuit of RA21-contact RA11-brush 9-slip ring 5-brush 8 is constructed. This point corresponds to time 60 in FIG. At time 61, when the treadle 22 is returned to the neutral state and simultaneously pushed in the direction B, the clutch wheel 14 is moved back to the engaged flywheel 12.
and engages with the low speed disk 32. Also, the switch 24 is closed to the b side, but at this time, the first relay RA1 is still in the energized state, so the contacts 24 and
The third relay RA3 is energized through RA13, and the capacitor 52 is charged through the contact 24 and RA14. As the third relay RA3 is energized, its contacts RA31 and RA32 are closed and the auxiliary motor A is driven. Therefore, the sewing machine is driven by the auxiliary motor via the auxiliary motor's small pulley 28, belt 34, medium pulley 31, gear 35, low speed disc 32, and clutch wheel 14, and rotates at a low speed. Point 62 indicates this.
On the other hand, as the footboard 22 is pushed in the direction B, the switch 26 closes, but at this point, the first relay RA1 is still energized, so the contact RA1
2 is closed to the a side, shorting the contact 26, so the second relay RA2 is not energized.

This state is the same even if the contact 26 is closed before the contact 24 returns to the b side. At time point 63, when the brushes 9 and 8 of the needle down position detection circuit described above are disconnected from each other by the insulating band 6 of the slip ring 5, the first relay RA1 is deenergized. As a result, contact RA12 closes to the b side, so contact 2
4, 26, and RA12, the second relay RA2 is energized and the contact RA13 is opened, so that the third relay RA3 is deenergized and the auxiliary motor A is released from the power source. Second relay RA2
The contact RA21 closes to the a side by the energization of the needle top position detection circuit having the brush 8, the slip ring 5, and the brush 7, and the first relay RA1 is energized again.

When the second relay RA2 and the first relay RA1 are energized, the contacts RA12, RA14, and RA15 are closed to the a side, charging the capacitors 52 and 55, and the contacts RA13, RA22, and RA23 are also closed, so that the third The relay RA3 is energized to drive the auxiliary motor A, while the base current flows to the transistor 51 through the resistor 50, making the transistor 51 conductive and energizing the electromagnet 58 for driving the thread cutting device. Also, as mentioned above, the first relay RA1
is deenergized, second relay RA2 is energized, and contact RA14 is switched from the a side to the b side in a short time when the first relay RA1 is energized again, so that the charged load of the capacitor 52 is transferred to the transistor. 54
Since the transistor 54 becomes conductive, the electromagnetic brake 29 is energized. However, since the first relay RA1 is immediately energized again, the contact RA14 is closed to the a side, and as a result, the electromagnetic brake 29 is deenergized. At time 65, when the brushes 7 and 8 of the needle top position detection circuit are disconnected by the insulating band 6, the first relay RA1 is deenergized and the contact RA
13 is opened, the third relay RA3 is also deenergized and the auxiliary motor A is stopped.

Further, since the contact RA14 closes to the b side, the electric charge of the capacitor 52 is discharged to the base circuit of the transistor 54, making it conductive and energizing the electromagnetic brake 29. As a result, the low speed disk 32 stops and the sewing machine needle 3 stops at a predetermined upper position. When the capacitor 52 is completely discharged, the transistor 54 becomes non-conductive and the brake is released. Note that the discharge time can be arbitrarily set depending on the capacitance of the capacitor 52 and the value of the resistor 53. Furthermore, contact RA13
By opening, the base circuit of the transistor 51 is opened, so that the transistor 51 becomes non-conductive and the electromagnet 58 for driving the thread cutting device is deenergized. Furthermore,
When the contact RA15 is closed to the b side, the electric charge of the capacitor 55 is discharged to the base circuit of the transistor 57, and the yarn removing device electromagnet 59 is energized to make the base circuit conductive. This device has capacitor 5
5 is discharged to the base circuit of the transistor 57 to make it conductive.
9 is energized. This device is deenergized upon completion of discharge of capacitor 55.

The above invention describes the case where the treadle 22 is returned to the neutral state, that is, released, and simultaneously pushed in the direction B, that is, backwards, but unless the treadle 22 is stopped in the released state and is not pushed backward, the contact 26 will not be closed. Since the second relay RA2 is not energized, the brushes 9 and 8 of the needle lower position detection circuit described above are not energized.
When the insulating band 6 of the slip ring 5 becomes non-conductive, the first relay RA1 is deenergized.
As a result, the contact RA14 is switched from the a side to the b side, so that the charge of the capacitor 52 is discharged to the base circuit of the transistor 54, and the transistor 5
4 becomes conductive, so the electromagnetic brake 29 is energized. As a result, the low-speed disk 32 stops, and the sewing machine needle 3 stops at a predetermined upper position. When the discharge of the capacitor 52 is completed, the transistor 54 becomes non-conductive and the brake is released.

After stopping at the upper position, when the treadle 22 is pushed further backward, the second
relay RA2 is energized. As a result, contact RA2
Brush 8, slip ring 5 because 1 closes on side a
A needle up position detection circuit having the brush 7 is constructed and the first relay RA1 is energized. In addition, contact RA14 is closed to the a side by energization of first relay RA1, charging capacitor 52, and contact RA13
By closing, the third relay RA3 is energized and drives the auxiliary motor A.

When the brushes 7 and 8 of the needle top position detection circuit become non-conductive due to the insulating band 6, the first relay RA1 is deenergized and the contact RA13 is opened, so that the third relay RA3 is also deenergized and the auxiliary relay is deenergized. Motor A stops.

Further, since the contact RA14 closes to the b side, the electric charge of the capacitor 52 is discharged to the base circuit of the transistor 54, making it conductive and energizing the electromagnetic brake 29. As a result, the low speed disk 32 stops and the sewing machine needle 3 stops at a predetermined upper position. When the capacitor 52 is completely discharged, the transistor 54 becomes non-conductive and the brake is released. By changing the position of the insulating band 6 of the slip ring 5, the footboard 22 can be stopped at the upper position when released and at the lower position when pushed backward.

Since this invention is configured as described above,
When the treadle 22 is pushed in the A direction and then returned to the neutral state, the needle is stopped at a predetermined position, and when the tread plate 22 is further pushed in the B direction, the needle is stopped at another predetermined position. It can be done without any trouble. Also, without operating another switch,
Since it is operated in conjunction with the footboard 22, operability is good. Furthermore, after pushing the treadle 22 in the A direction, a series of operations of pushing it in the B direction from the neutral state detects a predetermined position, drives the thread trimming device, stops it at a predetermined position, and then smoothly drives the thread removing device. I can make you do it. Stopping at a predetermined position is performed by energizing the electromagnetic brake 29 provided at the shaft end of auxiliary motor A, and this energizing time is the time required for stopping (generally within 50 msec). After the capacitor is discharged, the brake 29 is released, so the sewing machine shaft is released from the braking state. Even when it is desired to rotate the sewing machine by hand for threading work, etc., the sewing machine can be rotated freely.
Further, the energizing time of the electromagnet for driving the thread removing device may be set to a time sufficient to drive the thread removing device by selecting the values of the capacitor 55 and the resistor 56. In particular, according to the invention, since the thread wiping time is shorter than the brake application time, the brake 29 is activated during a short period of time when the thread wiping device is in operation, and thread wiping can be done safely and reliably without the needle moving. It is possible. Now, even if the treadle 22 is returned to the neutral state from the state where it was pushed in the B direction at time 64, the contact point
Since RA12 is closed to the a side and short-circuits the contact 26, the second relay RA2 continues to be energized and the thread trimming device electromagnet 58 continues to be energized to perform thread trimming. If you accidentally push the footboard 22 in the A direction from the neutral state, the switch 24 will close to the A side, so the second relay RA2 and the third relay
Both the RA 3 and the electromagnet 58 for the thread trimming device are deenergized, and the thread trimming device is disconnected before the sewing machine is operated at high speed to protect the device.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a diagram showing a control circuit of the above embodiment, and FIG. 3 is an explanatory diagram showing an operation process. In the figure, 1 is the sewing machine table, 2 is the sewing machine body,
3 is the needle, M is the main motor, A is the auxiliary motor, 2
2 is a footboard, 17 is a clutch lever, 24 and 26 are micro switches, 31 is a medium pulley, 32 is a low speed disc, RA1, RA2, and RA3 are each a relay, 29
58 is an electromagnetic brake, 58 is an electromagnet for the thread cutting device, and 59 is an electromagnetic brake.
is an electromagnet for a thread removing device.

Claims (1)

[Claims] 1. A sewing machine drive unit that drives the sewing machine at high speed or at low speed to stop the sewing machine needle in a fixed position, a brake unit that stops the sewing machine in a fixed position, and the lower and upper positions of the sewing machine needle. a position detector for detecting the sewing machine; a treadle for operating the sewing machine; a high-speed operation circuit that controls the drive unit to drive the sewing machine at high speed when the treadle is pressed forward; a first low-speed operation fixed-position stop circuit that controls the drive section and the brake section to drive the sewing machine at low speed and stop the sewing machine needle at the lower or upper position detected by the position detector; a second low-speed operation fixed position stop circuit which, when pressed, continues to operate the drive unit at low speed to drive the sewing machine needle to another upper or lower position detected by the position detector and then stops; The brake section includes a thread trimming device that is driven while reaching a different position after detecting a predetermined position, and a thread removing device that is driven within a certain period of time when the sewing machine needle stops at the predetermined position. A sewing machine drive device characterized in that a timer is used to automatically maintain an energized state for a longer time than the operating time of a thread wiper.