JPS5953071B2 - Sewing machine motor speed control switching device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a motor speed control switching device for a sewing machine, and more particularly, the present invention relates to a motor speed control switching device for a sewing machine. This relates to a sewing machine with a built-in controller, in which the motor is configured to rotate at a selected and set constant speed during steady operation after the sewing machine has started. It is an object of the present invention to provide a device capable of controlling the operation of a sewing machine not only by hand but also by an operator's foot operation as required.

As this type of device, a device as described in Japanese Utility Model Application Publication No. 49-44459 has already been proposed.

In this device, a foot-type controller is removably connected to the sewing machine body, but the speed control of the motor by foot operation of this controller is a step-by-step speed control, which is different from conventional continuous variable speed control. do not have. Therefore, a newly designed special controller must be used as a foot-operated controller, which has the drawback of making the sewing machine extremely expensive. The present invention has been made in view of the above-mentioned circumstances, and allows the use of the conventionally commonly used continuously variable speed control system as the foot-operated controller, thereby minimizing the increase in the price of the sewing machine. The advantages of a sewing machine with a built-in controller and the advantages of a sewing machine with a foot-operated controller can be easily used as needed, and the safety issues associated with conventional foot-operated controllers, such as the use of the sewing machine, can be easily used. A device that eliminates the risk of the sewing machine suddenly starting up if the foot-operated controller is pressed by mistake during an interruption, or even if the sewing machine does not start, low power is supplied to the motor and the motor heats up. This is what we are trying to provide.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an apparatus embodying the present invention will be described below with reference to the drawings.

Fig. 1 shows the appearance of a sewing machine with a built-in controller.
This pushbutton is used to select and set medium speed or low speed, and is arranged in parallel with the pushbutton 4 for turning on the power on the front side of the sewing machine body.

5 controls the operation and stopping of the sewing machine. The control lever is rotatably mounted on the front side of the head of the sewing machine body and can be selectively moved to at least a sewing machine stop position P1 and a sewing machine operating position P2.

6 is a plug for connecting a first motor speed control device installed inside the sewing machine body and will be described later to an AC power source, and 7 is a plug for connecting a second motor speed control device installed outside the sewing machine body and described later. It is a foot-operated controller, and is connected to the sewing machine main body via a plug 8 as a connecting body.

The specific circuit configurations of the first and second motor speed control devices will now be described with reference to FIG. 3. 9,
Reference numeral 10 denotes a power terminal connected to an AC power supply via the plug 6, and 11 a power switch 12 which is opened and closed by operating the push button 4, and a changeover switch (to be described later) 3, which is led out from the power supply terminal 9. One AC bus, 1
Reference numeral 4 designates the other AC bus bar led out from the power supply terminal 10, and between the two bus bars 11 and 14, there is a motor 15 for driving the main shaft (not shown) of the sewing machine such as a commutator motor, and power to the motor is connected. A thyristor 16 as a first power control element for controlling supply is connected in series.

A protective varistor 17 is connected in parallel to this thyristor, and a parallel circuit consisting of a resistor 18 and a capacitor 19 is connected between the gate and cathode of the thyristor 16 as means for preventing erroneous firing. Furthermore, the bus bar 11
, 14, a signal level setting circuit for setting the level of the trigger signal to the thyristor 16 is connected via a second thyristor 20, and this setting circuit includes a plurality of resistors 21 to 27 and a diode. 28, 29, and each slider 2 of the resistors 24, 25, and 27.
4a, 25a and 27a, one end of which is connected to each of speed setting selection switches 30 to 32, and the resistor 2.
A phase shifting capacitor 33 connected in parallel to the series circuits 4 to 27, a contact a connected to the other end of the selection switches 30 to 32, and a contact connected to the slider 27a of the resistor 27. b, and the fixed contact C is a diode 34,
and a changeover switch 36 connected to the gate of the thyristor 16 via a switch 35. The slider 27a is also connected to a connection point between the resistors 26 and 27. Further, the selection switches 30 to 32 are
Any one of the distance setting push buttons 1 to 3 is closed by pressing the distance setting push buttons 1 to 3 described above. Further, the changeover switch 36 is connected when the operating lever 5 is in the sewing machine stop position P1 indicated by the first (branch), and the operating lever 5 is moved to the sewing machine rotation position P2. It is linked with the operating lever 5 so that the contact point a is switched to the side when the contact point a is pressed. Furthermore, a resistor 3 is connected between the busbars 11 and 14.
7 and 38 are connected in series via the diode 29, and a series circuit consisting of a diode 39, a changeover switch 40 connected to the contact b side, and a capacitor 41 is connected between both of the resistors 38. . The other contact a of the changeover switch 40 is connected to the gate of the second thyristor 20 via a resistor 42 and a diode 43. Further, a potentiometer 45 is connected between the base and the emitter of a transistor 44 which is connected in parallel to the series circuit of the resistors 23 to 27 and the diode 28 to form a bypass circuit. One terminal of each of three resistors 46 to 48 arranged in the above is connected respectively, and the other terminal of each of these resistors is connected to each of the switches 49 to 51 and 48 which are opened and closed in conjunction with the selection switches 30 to 32, respectively. resistance 52
It is connected to the contact a side of the changeover switch 40 via. When the manual operation lever 5 is located at the sewing machine stop position P1, the changeover switch 40 contacts b.
When the operating lever 5 is located at the sewing machine operating position P2, the contact point a is switched to the side. Further, a capacitor 5 is connected between the connection point of the resistors 22 and 23 and the gate of the second thyristor 20.
3, a resistor 54, and a diode 55 are connected in series, and between the connecting point of the resistors 21 and 22 and the connecting point of the capacitor 53 and the resistor 54, a switch of the polarity shown is connected via an on/off switch 56. A diode 57 is connected.

The opening/closing switch 56 is connected to the operating lever 5 so that it is opened when the manual operating lever 5 is located at the sewing machine stop position P1, and closed when the operating lever 5 is moved to the sewing machine operating position P2. It is linked. In addition, 5
8 is a capacitor for noise prevention, and 59 is the power switch 12.
A lamp 60 is a resistor that lights up when the sewing machine is closed, and each element other than the power switch 12, changeover switch 13, motor 15, and lamp 59 constitutes a first motor speed control device A, which is installed inside the sewing machine body. ing. Next, to explain the second motor speed control device B, 61 is one AC bus derived from one contact a of the changeover switch 13, and 62 is one AC bus derived from the connection point between the motor 15 and the bus 14. On the other AC bus, a thyristor 63 as a second power control element is connected between the connection point of the thyristor 16 and the motor 15 and the AC bus 61, and a protective varistor 64 is connected in parallel to the thyristor 63. It is connected to the.

A series circuit of a resistor 65, a potentiometer 66, and a diode 67 is connected between the bus bars 61 and 62, and a slider 66a of the potentiometer 66 is connected to the gate of the thyristor 63 via a diode 68. There is. The slider 66a moves upward in the figure in accordance with the degree of pressing of the foot-operated controller 7 shown in FIG.
Note that the potentiometer 66 is equipped with a phase shifting capacitor 6.
9 are connected in parallel, and a parallel circuit of a resistor 70 and a capacitor 71 is further connected between the gate and cathode of the thyristor 63. This second motor speed control device B is installed in the controller 7. FIG. 4 is an actual wiring diagram based on the circuit configuration shown in FIG. 3, and 72 in the figure is a cord winding device; 73 to 78 are connection terminals;
79 to 81 are pin-shaped connection terminals constituting the plug 8 connected to the second motor speed control device B, and 82 is a socket 82 having terminal holders 83 to 85 into which the connection terminals 79 to 81 fit, respectively. The connection terminals 73 to 78 are installed in a connection terminal box 86, as shown in FIG.

That is, referring to FIG. 2, 87 is a sewing machine frame, 88 is a bracket fixed to the machine frame with screws 89, and 90 is a sewing machine frame.
The terminal box 86 is composed of a main body of a terminal box fixed to the bracket with screws 9 and a lid (not shown) covering the main body 90 of the terminal box. Reference numeral 92 denotes a terminal plate fixed inside the terminal box main body 90, and the connection terminals 73 to 7
8 is installed.

Reference numeral 93 denotes a switching lever rotatably attached to the terminal box main body 90, one end of which faces the actuator 13a of the changeover switch 13 fixed to the terminal box main body 90, and the switch 13 is normally operated as shown in FIG. It is maintained in the state where it is switched to the contact b side shown in .

The socket 82 having the terminal receiving fittings 83 to 85 faces outside the sewing machine frame through an opening 87a of the sewing machine frame 87, and when the plug 8 is fitted into the socket 82, The inner wall surface 8a engages with the contact head of the switching lever 93 to rotate the lever 93 clockwise in FIG.
When the actuator 13a of the switch 13 is pressed 7 times, the switch 13 switches to the third position.
In the figure, the contact point a is switched to the side, and the second motor speed control device B is connected to the motor 15 and connected to the AC power source via the power switch 12. The device of this embodiment has the above-mentioned configuration, and its operating mode will be explained below. 1 to 4, the second motor speed control device B installed in the foot-operated controller 7 is separated from the motor 15, and the manual operation lever 5 is separated from the motor 15.
This shows a state in which the sewing machine is located at the sewing machine stop position P1, the power switch 12 is opened, and the push button 1 for high speed setting is pressed, and the speed selection switch 30 and the interlocking switch 49 are closed. , other speed selection switches 31 to 32 and interlocking switch 5
0,51 are open. And changeover switch 13
, 36, and 40 are all switched to the contact b side, and the open/close switch 56 is open. When the push button 4 is pressed, the push button is held in the pressed state by appropriate means and the power switch 12 is closed.

As a result, a lamp 59 disposed inside the sewing machine head lights up, and the user of the sewing machine senses that the power has been turned on.
The capacitor 41 also includes a resistor 37, a diode 39,
It is instantly charged via the changeover switch 40. Therefore, in order to operate the sewing machine, the operating lever 5 is moved from position P1 to P2.
When the switch is rotated to , the changeover switches 36 and 40 are respectively switched to the contact a side, and the open/close switch 56 is closed.

By switching the changeover switch 40 to the contact a side, the electric charge of the capacitor 41 that has been charged up to that point is transferred to the resistor 4.
2. It is input to the gate of the second thyristor 20 via the diode 43, and this thyristor becomes conductive. Further, the electric charge of the capacitor 41 is transferred to a resistor 52 and an interlocking switch 49.
, is input to the base of the transistor 44 via the resistor 46, the slider 45a, and the resistor 45, and this transistor is turned on. Therefore, the current flowing from the bus 11 into the signal level setting circuit due to conduction of the second thyristor 84 is as follows.
At first, almost no current passes through the series circuit of resistors 23 to 27, detours to a bypass circuit consisting mostly of transistor 44, passes through diode 29, and flows to bus 14. As the discharge of the capacitor 41 progresses, the input to the base of the transistor 44 decreases, and the current flowing through the bypass circuit gradually decreases.
The current flowing through the series circuit gradually increases, and when the discharge of the capacitor 41 is almost completed, the transistor 44 is turned off and the bypass circuit is cut off. Therefore, the trigger signal to the first thyristor 16 from the signal level setting circuit is extremely small immediately after the changeover switches 3e) and 40 are switched to the contact a side, and the trigger signal to the first thyristor
6 is not made conductive instantly, but the signal level gradually rises to make the thyristor 16 conductive, power is supplied to the motor 15, and the motor is started. As the conduction angle of the thyristor increases, the motor 1
When the rotation speed of the motor 5 increases and the transistor 44 turns off, a trigger signal at a level set by the speed selection switch 30, which is selectively closed in advance, is input to the thyristor 16, and the motor 15 rotates at a predetermined speed. reach speed. By the way, when the second thyristor 20 conducts and current flows (during a positive half cycle), the on/off switch 56 is closed, so the capacitor 53 is charged, and when the next current does not flow (during a negative half cycle), the capacitor 53 is charged. ), the capacitor 53
The charge is input to the gate of the thyristor 20 through the resistor 541 and the diode 55, and the thyristor is kept in a conductive state.

Therefore, once the thyristor 20 is conductive, it remains conductive until the on-off switch 56 is released, that is, until the manual operation lever 5 is returned to the first position P1 for stopping the sewing machine and the capacitor 53 completes discharging. During this period, the capacitor 53 is repeatedly charged and discharged.
Therefore, after the transistor 44 is turned off, the motor 15 is driven to constant rotation at a preset rotation speed (high speed in this case). When the motor 15 is started, the main shaft (not shown) of the sewing machine is started, and the rotational speed is gradually increased until a predetermined rotational speed is reached, similar to when the foot-operated controller is gradually pressed. By operating the sewing machine in this manner, the desired sewing work is accomplished.

During this period, once the operating lever 5 is moved to the sewing machine operating position P2, even if the operator releases the rotational operation at that position P2, the operating lever 5 is moved to the sewing machine operating position P2 by appropriate means.
It is configured to be held in If the other push button 2 or 3 is pressed during the sewing work, the push button 1 is released, the selection switch 30 and the interlocking switch 49 are opened, and the other selection switch 31 or 32 is pressed. The thyristor 16 is closed together with the interlocking switch 50 or 51, and a trigger signal of a lower level than in the above case is input to the thyristor 16, and the motor 15 is driven at a corresponding rotational speed (medium speed or low speed). At this time, since the capacitor 41 has been discharged, the transistor 44 remains off. After performing the desired sewing work in this way, or in order to stop the operation of the sewing machine in the middle of sewing, the manual operation lever 5 is rotated back from the second position P2 to the first position P1. , the changeover switches 36 and 40 and the open/close switch 56 return to their original positions shown in FIG. The supply of electric power to the motor 15 via is cut off, and the motor 15 is stopped.

After the sewing machine has stopped, if the manual operation lever 5 is moved to the second position P2 again to start the next sewing,
In the same manner as described above, the sewing machine starts slowly, gradually increases its speed, and then operates steadily at a preset speed by pressing any of the speed setting push buttons 1 to 3. The above is the operation mode when the first motor speed control device A installed in the sewing machine body controls the power supply to the motor to start and stop the sewing machine. The operation mode when device B is used to operate and stop the sewing machine by controlling the supply of power to the motor by foot operation will be described.

When the plug 8 connected to the second motor speed control device B installed in the foot-operated controller 7 is inserted into the socket 82 fixed to the sewing machine body, the inner wall surface 8a of the plug 8
The switching lever 93 rotates and presses the operating protrusion 13a of the switching switch 13, thereby switching the switching switch 13 from the state shown in FIGS. 3 and 4 to the contact a side.

Therefore, the second motor speed control device B is connected to the motor 15 and to the AC power source, while the connection between the first motor speed control device A and the AC power source is cut off. Therefore, even if the operating lever 5 is operated, no power is supplied to the motor 15, and the sewing machine remains stopped. If the foot-operated controller 7 is pressed while the power switch 12 is closed by pressing the push button 4, the slider 6 of the potentiometer 66 will be moved in accordance with the degree of pressing.
6a moves, and the corresponding gate signal is sent to the thyristor 6.
3, the thyristor 63 becomes conductive, and electric power corresponding to the conduction angle is supplied to the motor 15, and the motor 15 is rotationally driven.

Therefore, the sewing machine is operated at a motor speed that is continuously changed and set according to the amount of pressure applied to the foot-type controller 7, and the sewing work is performed. At this time, no matter which of the speed selection switches 30 to 32 is closed by operating the speed setting push buttons 1 to 3, the change in the rotational speed of the motor 15 by pressing the controller 7 is not affected in any way. It is clear that there is no such thing. In this way, the second motor speed control device B is controlled by operating the foot-operated controller 7.
is activated and the speed of motor 15 can be continuously changed and set to accomplish the desired sewing task. Then, when the plug 8 is pulled out from the socket 82 on the sewing machine main body, the switching lever 93 is disengaged from the inner wall surface of the plug 8, so the switching switch 13 automatically returns to the contact b side, and the first Motor speed control device A is connected to an AC power source via power switch 12. At this time, even if the operating lever 5 is moved and held at the sewing machine operating position P2, the sewing machine will not start immediately. This is because the capacitor 41 is completely discharged when the changeover switch 40 is switched to the contact a side, so the second thyristor 2
This is because 0 is not conductive, so no gate signal is input to the first thyristor 16, and the thyristor 16 is maintained in a non-conductive state. It is clear from the above description that in order to start the sewing machine, it is sufficient to return the operating lever 5 to the sewing machine stop position P1 and then move it again to the sewing machine operating position P2. The device of this embodiment has the above-described configuration and operation mode, and the second motor speed control device B installed in the foot-type controller 7 is electrically connected to the motor 15 located in the sewing machine main body. By inserting the plug 8 into the socket 82 to connect to the sewing machine, the connection between the first motor speed control device A installed in the sewing machine body and the current is cut off, and the second motor speed control device A is disconnected from the current. Device B is connected to an AC power source via power switch 12.

Therefore, the foot-operated controller 7 equipped with the second motor speed control device B can be exactly the same as the conventional one, by simply changing the plug 8, and the power switch can be turned on or off by operating the push button 4. If the controller 12 is left open, even if the controller 7 is accidentally pressed, the sewing machine will not be started unexpectedly, making it safe. In this embodiment, changeover switches 36 and 40 and an open/close switch 5 are used as operating switches that can be operated by the operator's hand via the operating lever 5 in order to control starting and stopping of the motor.
6 is used, but by changing the configuration of the first motor speed control device A, it is possible to use one switch instead. As is clear from the above description, the present invention includes a speed selection and setting circuit for selecting and setting the rotational speed of a motor, and an operation switch that can be operated by an operator's hand to control starting and stopping of the motor. A first motor speed control device including a first power control element for controlling power supply to the motor is installed in the sewing machine body, and controls starting and stopping of the motor and continuously controls the speed of the motor. a second motor including a continuous speed setting circuit section actuated by foot operation to change settings; a second power control element for controlling power supply to the motor; and a connection body detachably connected to the motor. A speed control device is disposed outside the sewing machine main body, and the connection between the first motor speed control device and the AC power source is cut off in connection with the connection operation of the connecting body to the motor, and the second motor speed control device is disconnected from the AC power source. The sewing machine is equipped with a connection switching means that connects to an AC power source via a power switch, and is used to convert the operation control of the sewing machine from the operator's hands to the operator's feet. Of course, this can be done by simply connecting the motor speed control device to the motor, and it is also possible to use a conventionally used second motor speed control device as is. The connection to the power supply is through a common power switch with the first motor speed control device, so unlike traditional foot-operated controllers that are directly connected to the power supply, it is possible to open the power switch and If this is done, there will be no fear that the sewing machine will start up unexpectedly or the motor will overheat, thereby improving safety and having excellent practical effects.

[Brief explanation of the drawing]

The drawings show an embodiment embodying the present invention,
FIG. 1 is a perspective view showing the external appearance of the sewing machine, FIG. 2 is a partially cutaway plan view of a connection section, FIG. 3 is an electric circuit diagram, and FIG. 4 is an actual wiring diagram.

Claims (1)

[Scope of Claims] 1. A motor 15 mounted on the sewing machine body to drive the main shaft of the sewing machine, and speed selection and setting circuit units 21 to 27, 30 to 32 for selectively setting the rotational speed of the motor 15. , includes operation switches 36 and 40 that can be operated by the operator's hands to control starting and stopping of the motor 15, and a first power control element 16 that controls power supply to the motor 15, and is located inside the sewing machine body. , and controls the conduction of the first power control element 16 according to the speed set and selected by the speed selection and setting circuit sections 21 to 27 and 30 to 32, so that power is supplied from the AC power source via the power switch 12. A first motor speed control device A that controls the amount of electric power supplied to the motor 15; The sewing machine includes continuous setting circuit sections 66, 66a, a second power control element 63 that controls power supply to the motor 15, and a connecting body 8 that is detachably connected to the motor 15, and is disposed outside the sewing machine main body. By controlling conduction of the second power control element 63 according to the speed set by the speed continuous setting circuit sections 66 and 66a, power is supplied from the AC power source to the motor 15 via the connection body 8. cutting off the connection between the second motor speed control device B that controls the amount of electric power and the first motor speed control device A and the AC power source in connection with the connection operation of the connection body 8 to the motor 15; Connection switching means 13 provided within the sewing machine body for connecting the second motor speed control device B to the AC power source via the power switch 12
, 93. A motor speed control switching device for a sewing machine. 2 The connection switching means 13, 93 are connected to the plug operation when the plug 8, which is the connection body 8 of the second motor speed control device B, is connected to the motor 15 and inserted into the socket 82 fixed to the sewing machine body. 2. A motor speed control switching device for a sewing machine according to claim 1, comprising a switching lever 93 that is operated by the switching lever 93 and a switching switch 13 interlocked with the switching lever 93.