JPS6042753B2 - sewing machine safety device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a safety device for a sewing machine, and more particularly to a device for preventing motor burnout when the sewing machine motor is in a locked state.

Recently, sewing machines have been developed that are equipped with a power cutoff device that detects when the sewing machine motor locks up due to overload and automatically cuts off the power supply to the motor. When the sewing machine motor is not rotated for a predetermined period of time while the power is being supplied to the sewing machine motor, it is determined that the sewing machine is in a locked state and operates, thereby preventing burnout of the motor.

However, if a worker notices that the sewing machine motor is locked during sewing work, he or she forgets that the power supply to the sewing machine motor is automatically cut off by the action of the power cutoff device and hastily turns off the motor control operating means. If the control operating means is operated incorrectly at that time, there is a risk that the power supply to the sewing machine motor will be restarted and the motor may burn out. The present invention has been made in view of the above-mentioned circumstances, and includes instruction blocking means that operates in conjunction with the power cutoff operation by the power cutoff device and blocks a motor operation command by operating the motor control operating means for a certain period of time. It is an object of the present invention to provide a safety device that can reliably maintain a power cut-off state of a sewing machine motor for a certain period of time and make an operator aware of the power cut-off state. An embodiment embodying the present invention will be described below with reference to the drawings.

Reference numeral 1 indicates a start switch connected through a resistor 2 in series between the positive power supply terminal +Vcc and the zero potential terminal.When this is manually pressed, both contacts are opened, and when the pressure is released, both contacts are opened. The structure is such that the gap is restored to being closed.

Therefore, each time the starting switch 1 is pressed and released, a set pulse P1 that rises when the contacts are opened and falls when the contacts are closed is output from the anti-zero potential terminal side contact of the starting switch 1. Ru. Reference numeral 3 denotes a rising trigger type trigger flip-flop, and its clock input terminal T is connected to receive a set pulse P1 generated when the start switch 1 is pressed via an AND circuit 78, which will be described later.

This trigger flip-flop 3, every time the set pulse P1 input to its clock input terminal T rises,
In other words, it is triggered every time the start switch 1 is pressed, and the output from the output terminal Q is between the start command signal "H" consisting of a high level signal and the stop command signal "L" consisting of a low level signal. It has a reversible configuration. The trigger flip-flop 3 is reset synchronously when a rising signal is applied to its reset terminal RT and when the sewing machine is powered on, and when it is reset, the output from its output terminal Q is It operates so that the stop command signal becomes "L". 4 is a switching transistor 5
and a relay 6, the base of the transistor 5 is connected to the output terminal Q of the trigger flip-flop 3 via a resistor 7, the emitter is connected to the zero potential terminal, and the collector is connected to the excitation of the relay 6. It is connected to the positive power terminal +Vcc via the coil 6a.

Therefore, in the operating circuit 4, when the start command signal "H" is output from the output terminal Q of the trigger flip-flop 3, the transistor 5 is turned on, the normally open switch 6b of the relay 6 is closed, and the trigger flip-flop is turned on. When the stop command signal "L" is output from the output terminal Q of the relay 3, the transistor 5 is turned off and the normally open switch 6b of the relay 6 is opened. 8 is an AC power supply, and both output terminals are connected to the induction coil 9.
and a noise prevention filter 11 consisting of a capacitor 10 and a capacitor 10.
are connected to busbars 12 and 13, respectively.

Between the bus bars 12 and 13, there is a series circuit of a sewing machine motor 15, for example, a series-wound commutator motor, which is operatively connected to the anode and cathode of a thyristor 14 for phase control and to the main shaft of the sewing machine (not shown). A voltage dividing circuit 21 consisting of a polar diode 16 and a series circuit of resistors 17, 18, 19, and 20 is connected, respectively. A parallel circuit consisting of a resistor 22 and a capacitor 23 is connected between the gate and cathode of the thyristor 14, and a varistor 24 for protecting the thyristor 14 is connected in parallel between the anode and cathode of the thyristor 14. ，
A capacitor 25 is connected in parallel with the series circuits 19 and 20. 26 is a changeover switch for switching the rotational speed of the sewing machine motor 15 to any one of "high speed", "medium speed", and "low speed", and its high speed contact H1, medium speed contact M, and low speed contact L are the same as those described above, respectively. It is connected to a predetermined voltage tap in the voltage dividing circuit 21, and the movable contact C is a normally closed switch 27b of the tacking switch 27, which will be described later, and the relay 6.
The thyristor 14 is connected to the thyristor 14 through the normally open switch 6b in series.
connected to the gate. The tacking switch 27 has a normally closed switch 27a that is manually pressed, and a normally closed switch 27b and a normally open switch 27c that are respectively linked to the pressed operation of the normally closed switch 27a.
A series circuit of the normally closed switch 27a and the resistor 28 is connected between the positive power supply terminal Vcc and the zero potential terminal. Therefore, each time the tacking switch 27 is pressed and released, the tacking selection pulse P2 which rises when the normally closed switch 27a is opened and falls when the normally closed switch 27a is closed becomes the anti-zero potential of the normally closed switch 27a. Output from the terminal side contact. The normally open switch 27c is the gate of the thyristor 14 and the low speed contact L of the changeover switch 26.
This constitutes a gate circuit 29. The flip-flop 3, relay 6, thyristor 1
4, the voltage dividing circuit 21, the gate circuit 29, etc. constitute the control means of the present invention. Reference numeral 30 designates a pattern selection switch having the same configuration as the starting switch 1 for selecting a desired stitch pattern from among a variety of predetermined stitch patterns, and a resistor is connected between the positive power terminal +Vcc and the zero potential terminal. 64 are connected in series.

Each time the pattern selection switch 30 is pressed and released, the selection detection pulse P3, which is a selection detection signal that rises when both contacts of the pattern selection switch 30 are opened and falls when the contacts are closed, is applied to the anti-zero potential terminal of the pattern selection switch 30. Output from the side contact. Reference numeral 32 denotes an OR circuit connected to receive the tacking stitch selection pulse P2 and the selection detection pulse P3 as inputs separately, and its output terminal is connected to one input terminal of the OR circuit 31 via the line L1. The output terminal of the OR circuit 31 is connected to the reset terminal RT of the trigger flip-flop 3.

Reference numeral 33 denotes a pattern forming control device which controls the lateral swing movement of the sewing needle and the feed movement of the work cloth in the pattern sewing machine, and will be described below.

34 is a monostable multivibrator that is connected to receive the selection detection pulse P3 as an input and is triggered when the bus P3 falls; 35 is a monostable multivibrator that receives the output signal of this monostable multivibrator 34 via line L3 as a counting power; For example, a pattern counter with a 3-bit configuration is connected to receive
The eight types of count contents up to November are output as pattern selection codes corresponding to each of the eight types of stitch patterns such as straight stitches and zigzag stitches.

36 is a timing pulse generator that generates a timing pulse in synchronization with the vertical reciprocating motion of the sewing needle as the sewing machine motor 15 rotates; specifically, the sewing needle moves from a needle-top position above the sewing machine bed surface to a lower position on the sewing machine bed surface. A timing pulse SP is generated that rises a predetermined time after the timing when the sewing needle is displaced from the needle down position to the needle up position, and falls after a predetermined time after the timing when the sewing needle is displaced from the needle down position to the needle up position.

37 is connected to receive the timing pulse SP from the timing pulse generator 36 as an input signal via the inverter 38, and is triggered at the fall of the signal from the inverter 38, in other words, at the fall of the timing pulse SP. A monostable multivibrator 39 generates a feed timing pulse FC from the monostable multivibrator 37.
For example, a 4-bit stitch counter is connected to receive P as a counting power and outputs the counted contents as an address code.

Reference numeral 40 denotes a semiconductor memory device in which amplitude information for determining the falling position of the sewing needle and controlling its lateral swinging motion in order to form each of the eight types of stitch patterns is stored in the order in which the stitches are formed. The eight types of amplitude information groups and the feed information paired with the amplitude information that determines the feed amount of the work cloth and controls the feed movement in order to form each of the eight types of stitch patterns are This is to obtain eight types of sending information groups stored in the order of formation.

The semiconductor storage device 40 also has a pattern counter 35.
The pattern selection code from 39 and the address code from the stitch number counter 39 are connected so that they are supplied separately, and the pattern selection code selects a pair of amplitude information group and feed information group, and simultaneously selects the pair of amplitude information group and feed information group. A pair of amplitude information and feed information sequentially designated by the address code of each information group and stored in each address are transferred to line groups LA and LB, respectively.
The data is output sequentially via the . 41 is line group LA
A multi-input AND circuit is connected to receive output signals from each as an input signal, and its output terminal is connected to one input terminal of the OR circuit 42. The other input terminal of the OR circuit 42 is connected to receive the output signal from the OR circuit 32 via the line L1, and its output terminal is connected to the reset terminal RT of the stitch number counter 39. Incidentally, in each of the eight types of amplitude information groups stored in the semiconductor storage device 40, the termination code "11 November" is stored as the final information, and therefore one stitch corresponding to the selected amplitude information group is stored. When the stitch formation is completed and the termination code is output via the line group LA, this is sent to the stitch number counter 3 via the AND circuit 41 and the OR circuit 42.
9, and the count contents of the stitch number counter 39 are reset to "0000" each time the formation of one stitch pattern is completed. A needle height detector 43 generates a pulsed needle height signal NUP that becomes low level when the sewing needle is located at a predetermined position above the surface of the sewing machine bed.

44 is an AND circuit, one input terminal of which is connected to receive the needle-up signal JN[JP from the needle-up detector 43 via an inverter 45, and the other input terminal of which receives the needle-up signal JN[JP from the needle-up detector 43; It is connected to the output terminal via line L3, and therefore, the AND circuit 44 allows the signal from the monostable multi-i piper 34 to pass only while the needle up signal NUP is being output.

46 is an OR circuit, and both terminals are connected to the AND circuit 4.
4 and the output terminal of a monostable multivibrator 47 which is connected so as to be triggered at the falling edge of the timing pulse SP from the timing pulse generator 36 and generate an amplitude timing pulse AF.

48 is an AND circuit, one input terminal of which is connected to the output terminal of the OR circuit 46, and the other input terminal of which connects the tacking selection pulse P2 to the line L2 and the inverter 4.
Therefore, the AND circuit 48 allows the signal from the OR circuit 46 to pass only while the tacking selection pulse P2 is not being output.

Reference numeral 50 denotes a latch connected to receive amplitude information output from the semiconductor storage device 40 via the line group LA as an input signal, and its clock input terminal CK is connected to the output terminal of the AND circuit 48 via a delay circuit 51. connected.

The latch 50 receives the needle-up signal N from the needle-up detector 43 when the lock stitch selection pulse P2 is not output.
When the pattern selection switch 30 is pressed while UP is being output, the output signal or amplitude timing pulse BCP of the monostable multivibrator 34 passing through the AND circuit 44 is applied to its clock input terminal CK. Amplitude information read from the semiconductor memory device 40 is stored. 52 is an AND circuit, one input terminal of which is connected to receive the timing pulse SP from the timing pulse generator 36, and the other input terminal is connected to the output terminal of the monostable multivibrator 34. , therefore, the AND circuit 52 receives the timing pulse S
Monostable multivibrator 3 only while P is output
Allows the signal from 4 to pass.

53 is an OR circuit, and both terminals are connected to the AND circuit 5.
2 and the output terminal of the monostable multivibrator 37, respectively.

54 is a latch connected to receive the sending information output from the semiconductor memory device 40 via the line group LB as an input signal, and its clock input terminal CK is connected to the OR circuit. It is connected to the output terminal of 53 via a delay circuit 55.

The latch 54 is connected to a monostable multiplier that passes through an AND circuit 52 when the pattern selection switch 30 is pressed during a period in which the timing pulse SP is output from the timing pulse generator 36. Information read from the semiconductor storage device 40 at the time when the output signal of the vibrator 34 or the sending timing pulse FCP is applied to the clock input terminal CK is stored. The amplitude information stored in the latch 50 as described above is converted into an analog signal by the DA converter 56, which is supplied to the amplitude control actuator 58 via the amplitude control driver 57. The amplitude control actuator 58 determines the lateral position of the sewing needle for one stitch formation in accordance with the amplitude information stored in the latch 50 described above. On the other hand, the sending information stored in the latch 54 is sent via the multiplexer 59 to the D-A
The signal is supplied to the converter 60 and converted into an analog signal by the DA converter 60, and then supplied to the feed control actuator 62 via the feed control driver 61. This feed control actuator 62 determines the feed amount and feed direction of the feed dog for forming one stitch according to the feed information stored in the latch 54 described above. One stitch pattern has a corresponding pair of amplitude information and all the information in the feed information group.The stitch count counter 39 performs one round of counting operations until the end code of each information group is read out. By repeating this cycle, the same type of stitch pattern is continuously formed. Reference numeral 63 denotes an auxiliary storage device in which tacking feed information for forming tacking stitches different from the above-mentioned stitch pattern by giving a unique feed amount to the work cloth when tacking stitches are performed; It is connected to output the tacking feed information to a multiplexer 59 which is connected to receive feed information from the latch 54 as an input signal.

The select terminal SL of the multiplexer 59 is connected to receive the tacking selection pulse P2 outputted when the tacking switch 27 is pressed via the line L2, and the tacking selection pulse P2 is transmitted to the selection terminal SL. S
In the state where the tacking stitch selection pulse P2 is applied to the select terminal SL, the tacking stitch feed information from the auxiliary storage device 63 is supplied to the DA converter 60, and in the state where the tacking stitch selection pulse P2 is not applied to the select terminal SL, the tacking stitch feed information is supplied from the latch 54. The configuration is such that the sending information is supplied to the DA converter 60. 70 is an oscillator that generates a repetitive pulse signal at a frequency of 100 Hz, and the counter 7
1 counts the pulse signal, and the count contents are w-adic numbers.
127'', a high-level pulse signal is generated as a carry signal from the carry terminal CY, and when the high-level signal is supplied to the reset terminal RT, the count content becomes ``0'' in D base. will be reset.

The oscillator 70 and counter 71 are provided to constitute a detection means in the present invention. The monostable multivibrator 72 operates as a timekeeping means in the present invention, and is triggered in response to the carry signal, that is, in response to its rising signal, and generates a pulse signal of a constant time width at its output terminal. In the example, the time width is set to 5 seconds. The monostable multivibrator 72 is connected so that the pulse signal having a constant time width is applied to the base of a switching transistor 73 via a resistor 74 and is also supplied to an input terminal of an OR circuit 75. The emitter of the switching transistor 73 is connected to the zero potential terminal, and the collector is connected to the positive power terminal +Vc via the excitation coil 76a of the relay 76.
connected to c. Normally closed switch 7 of the relay 76
6b is connected between the connection point of the normally open switch 6b and the normally open switch 27c and the gate of the thyristor 14, and a pulse signal of a constant time width is supplied to the base of the switching transistor 73, so that the transistor 73
When the normally closed switch 76b is turned on, the normally closed switch 76b is opened and the connection between the gate of the thyristor 14 and the gate circuit 29 is cut off. The output terminal of the monostable multivibrator 72 is connected to the other input terminal of the OR circuit 31 via the line L5, and is also connected to the input terminal of the AND circuit 78 via the line L5 and the inverter 79. The output terminal of the vibrator 47 is connected to the input terminal of the OR circuit 75 via the line L4, and another input terminal of the OR circuit 75 is connected to the output terminal of the AND circuit 77. is connected to the reset terminal RT of the counter 71. Both terminals of the AND circuit 77 are connected to the output terminal of the inverter 49 and the inverting output terminal O of the trigger flip-flop 3 through the line L6.
, L7. AND circuit 7
Reference numeral 8 constitutes command blocking means in the present invention, the trigger flip-flop 3, relay 6, OR circuit 31, etc. constitute operating means in the present invention, and the start switch 1 controls the operation of the sewing machine motor 15. It also corresponds to the operator operation means for instructing its stop. Next, the operation of the above configuration will be explained. However, regarding the operation of the pattern formation control device 33, the present applicant has previously filed a patent application filed in 1982-1.
500 and is not directly related to the present invention, its explanation will be omitted here. After the desired stitch pattern is selected by the pattern selection switch 30, the start switch 27 is not pressed and the trigger flip-flop 3 is in the reset state, so the output signal of the inverter 49 and the flip-flop The output signals from the output terminals 3 and 3 are each in a high level state, and the AND circuit 77 supplies the high level signal to the reset terminal RT of the counter 71 via the OR circuit 75, and the counter 71 is in the reset state and is in the simple state. The stable multivibrator 72 turns off the transistor 73 to keep the normally closed switch 76b of the relay 76 closed, and also supplies a high level signal to the AND circuit 78 via the inverter 79 to open the AND circuit 78. let

Subsequently, when the start switch 1 is pressed to form the selected stitch pattern, the trigger flip-flop 3 is set and outputs a high level signal from its output terminal Q, and upon receiving the output signal, the transistor 5 is activated. is turned on to close the normally open switch 6b of the relay 6. Further, the output terminal O of the flip-flop 3 becomes a low level state, and the AND circuit 77 releases the reset state of the counter 71, and from that point on, the counter 71 starts counting pulse signals from the oscillator 70. Since the normally open switch 6b and the normally closed switches 27b and 76b are in the closed state, a speed command voltage having a value corresponding to the speed selected by the changeover switch 26 is supplied to the gate of the thyristor 14. is controlled to fire, and its thyristor 14
ignition, the sewing machine motor 15 is driven at the selected speed, and the selected stitch pattern is continuously formed by the action of the pattern formation control device 33. During the formation of the stitch pattern, A timing pulse SP is repeatedly generated from the timing pulse generator 36, and the monostable multivibrator 47, which receives the fall of the pulse SP, repeatedly generates a pulse signal and outputs the signal to the reset terminal of the counter 71 via the line L4 and the OR circuit 75. RT, and its counter 71 is reset before the count reaches "127" in decimal, without generating a carry signal.
Each time it is reset, the counting operation starts repeatedly from "0". The above operation is performed when the sewing machine motor 15 is rotating normally, but if the sewing machine motor 15 is overloaded by sewing thick work cloth, the sewing machine motor 15 may not rotate. timing pulse S to the monostable multivibrator 47.
The falling edge of P is no longer supplied, and the counter 71 continues counting without being reset.

The counting operation of the counter 71 continues and the counting contents become “
127'', that is, when it is detected that the sewing machine motor 15 is locked, the counter 71 generates a carry signal as an abnormal signal to trigger the monostable multivibrator 72. The monostable multivibrator 72 supplies a pulse signal with a constant time width to the transistor 73 to open the normally closed switch 76b of the relay 76, whereby the speed command voltage from the changeover switch 26 is supplied to the gate of the thyristor 14. At the same time, the AND circuit 78 is closed in response to the pulse signal having a constant time width, and the set pulse P1 outputted from the starting switch 1 is prevented from being supplied to the flip-flop 3. Further, the pulse signal having a certain time width is supplied to the reset terminal RT of the counter 71 and the flip-flop 3, so that the counter 71 stops the counting operation, and the flip-flop 3 sets its output terminal Q to a low level state to signal a stop command. Output. When the pulse signal with the constant time width disappears, the transistor 73 is turned off, and the normally closed switch 76b of the relay 76 is closed, and the AND circuit 7 is turned off.
8 is opened and set pulse P1 from start switch 1
will now be allowed to pass through. On the other hand, as long as the flip-flop 3 is in the reset state, the AND circuit 77 continues to stop the counting operation of the counter 71 by receiving a high level signal at its both input terminals. As a result, the power supply to the sewing machine motor 5 is cut off and the cut-off state is maintained for a certain period of time, and the operator notices that the power supply to the sewing machine motor 15 has been automatically cut off during the certain period of time. I can do it. In this embodiment, the sewing machine motor 15 is commanded to start and stop in accordance with the pressing operation of the start switch 1, and the sewing machine motor 15
The operation of instructing the operation and stopping of the operation is possible, and the former is as described above, and the latter will be explained below. When the tacking switch 27 is pressed to perform tacking before or after forming a stitch pattern, the normally closed switch 2 remains closed for the period that the tacking switch 27 is pressed.
At the same time that the tacking selection pulse P2 is output from the anti-zero potential terminal side contact of 7a, the normally closed switch 27b is opened and the normally open switch 27c is closed. As a result, a relatively small divided voltage by the resistor 20 in the voltage dividing circuit 21 is applied to the gate of the thyristor 14 via the normally open switch 27c forming a part of the gate circuit 29, so that the thyristor 14 is turned on and off. The phase control operation is started when the angle is relatively small, and the sewing machine motor 15 supplies relatively small electric power regardless of the start command signal "H" and stop command signal "L" from the trigger flip-flop 3. As a result, the trigger flip-flop 3 is rotated at a low speed.
is reset by supplying the tacking selection pulse P2 to its reset terminal RT via the OR circuit 32 and line L1, and outputs a stop command signal "L" from its output terminal Q. Therefore, the normally open switch 6b of the relay 6 is opened in response to the pressing operation of the lock stitch switch 27. On the other hand, due to the generation of the tacking stitch selection pulse P2, the output signal of the inverter 49 goes to a low level state, thereby closing the AND circuit 77, whereby the counter 71 is released from the reset state and starts the counting operation. As the sewing machine motor 15 rotates at a low speed, the pattern forming control device 33 acts to continuously perform tacking, and the monostable multivibrator 47 generates a pulse signal in response to the timing pulse SP and repeatedly resets the counter 71. If the rotation of the sewing machine motor 15 stops during this tacking operation and the stopped state continues, the counter 71 outputs a carry signal as described above to trigger the monostable multivibrator 72 and close the normally closed switch of the relay 76. 76b is opened for a certain period of time, the counter 71 is reset and stops counting, and the flip-flop 3 is reset to open the normally open switch 6b of the relay 6, and the AND circuit 78 is closed to close the start switch 1. Set pulse P from
Prevent passage of 1. This blocking operation is exactly the same as when the locked state occurs when the sewing machine motor 15 is driven in accordance with the pressing operation of the start switch 1, and the open state of the normally closed switch 76b is caused by the pressing operation of the tacking switch 27. The closed state of the AND circuit 78 is used to prevent the operation command of the sewing machine motor 15 from being issued by pressing the start switch 1. And the AND circuit 78
The closed state of the flip-flop 3 is maintained in a reset state by a pulse signal of a fixed time width until the pulse signal disappears, and after the pulse signal disappears, the sewing machine motor 15 is guaranteed to be stopped. It is also effective for In this embodiment, the worker is not actively warned of the locked state of the sewing machine motor, but it is of course possible to provide a means for performing a warning operation in response to the carry signal from the counter 71 if necessary. It is. As is clear from the above description, the present invention provides a timing means that measures a predetermined period of time when a locked state of a sewing machine motor is detected and the power supply to the motor is cut off, and a worker who By providing a command blocking means for blocking a motor operation command from the operating means to the control means, the operator operating means can be stopped immediately after the locked state of the sewing machine motor is detected and the power supply to the motor is automatically stopped. It is possible to reliably prevent resumption of power supply to the motor according to the operation. Even if a worker who is unfamiliar with sewing machines operates the operating means without recognizing the locked state of the sewing machine motor, resumption of power supply to the motor is prohibited while the timing means is operating, and the motor is cooled down during that time. Since this is carried out, heating or burning out of the sewing machine motor can be completely prevented.

[Brief explanation of the drawing]

The drawing is an electrical wiring diagram showing an operation control section of a sewing machine to which the present invention is applied. In the figure, 1 is a starting switch, 3 is a trigger flip-flop, 5 is a switching transistor, 6 is a relay, 1
4 is a thyristor, 15 is a sewing machine motor, 27 is a lock stitch switch, 70 is an oscillator, 71 is a counter, 72 is a monostable multivibrator, 73 is a switching transistor, 75 is an OR circuit, 76 is a relay, 77 is an AND circuit, 78 is an AND circuit.

Claims (1)

[Claims] 1 Sewing machine motor 15 operatively connected to the sewing machine main shaft
, an operator operation means 1 that can be operated to command the operation and stop of the sewing machine motor 15, and power supply to the sewing machine motor 15 in accordance with the operation command and stop command from the operator operation means 1. and control means 3, 6, 14, 21, 29 for shutting off the control means, and detects when the sewing machine motor 15 is in a locked state in a sewing machine that sequentially forms stitches as the main shaft rotates. detecting means 70, 71 for generating an abnormal signal, and controlling means 3, 6, 14 for stopping the sewing machine motor 15;
.
2, and command blocking means 78 for blocking the operation command of the sewing machine motor 15 from the operator operating means 1 to the control means 3, 6, 14, 21, 29 during the time counting operation of the time measuring means. A safety device for sewing machines that is characterized by: