JP2001029680A - Controller for sewing machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To completely prevent next sewing from being disturbed by surely restraining an induction motor even when an external force is suddenly applied to the sewing machine main shaft or the like during the stoppage of a sewing machine and to provide a controller for that purpose at a low cost. SOLUTION: When the activation of the sewing machine is cammanded (S10), corresponding to the rotation speed command of the sewing machine, an inverter is PWM controlled so as to obtain the output of the inverter of a voltage and a frequency corresponding to the rotation speed command. Also, in the case that the sewing machine main shaft is erroneously rotated during the stoppage of the sewing machine, when a rotation detector 18 detects the edge of the rise of encoder signals (S21, YES), the output time T1 of a DC voltage is set to a timer, the DC voltage of V1 is applied to the induction motor through the inverter, the torque of an opposite direction to the rotation is applied and restraint control is performed. Then, after the lapse of the output time T1 (S23, YES), an output voltage is set to V0 and the application of the DC voltage is stopped (S24). Thereafter, the restraint control similar to the above-mentioned one is executed in the case of detecting the edge of the fall of the encoder signals as well.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sewing machine control device for controlling a sewing machine using an induction motor as a driving motor.

[0002]

2. Description of the Related Art Conventionally, this type of control device controls the start / stop of a sewing machine in response to a command from a foot pedal or the like operated by an operator, the speed of the sewing machine at startup (that is, the rotation speed of the main shaft of the sewing machine), and the like. For control, an inverter 30 as shown in FIG. 5 is provided as a drive circuit of the induction motor.
The inverter 30 shown in FIG. 5 is used in a control device including a three-phase induction motor as a sewing machine motor.

This inverter converts, for example, a power supply voltage obtained by temporarily converting a commercial power supply into a DC voltage into a sine-wave AC having a predetermined frequency and a predetermined voltage, and supplies the converted AC voltage as a drive signal to an induction motor. As a result, the sinusoidal alternating current (3 in FIG. 5) having a different phase is applied to each phase winding of the induction motor.
In the case of a phase induction motor, the phase difference is 120 degrees), and the induction motor is rotated at a torque and a speed corresponding to the voltage and frequency of the drive signal. As shown in FIG. In order to apply a positive / negative voltage to each terminal, a pair of positive and negative switching elements (transistors in the figure) 31 to 36 are provided for each terminal. Then, in the control device of the sewing machine, in order to output a sine wave alternating current from the inverter, each of the switching elements is turned ON / OFF by a PWM signal pulse-width modulated at a predetermined cycle.

When the sewing machine is started based on the inverter constructed as described above and then stopped, the motor is returned from the sewing machine control circuit to the neutral position by releasing the foot pedal and returning it to the neutral position. A stop command is output to the control circuit, and in order to operate the sewing machine at an extremely low stop speed, a minimum stop frequency set in advance is set to the output frequency of the inverter, and the set frequency and the voltage corresponding thereto are set. By outputting the signal to the PWM signal generation circuit, the induction motor, and hence the sewing machine, is operated at the stop speed. After that, when the needle lower position or the needle upper position is detected, the sewing machine stops at that position.
The frequency commanded to the WM signal generation circuit, that is, the output frequency from the inverter is set to zero, the output of the inverter is held at the current output, the stop time of the sewing machine is set in the timer, and the carrier of the PWM signal is set. A carrier frequency for stopping the sewing machine that is lower than a carrier frequency for driving the sewing machine is set as the frequency, and the carrier frequency of the PWM signal generated by the PWM signal generation circuit is changed. Subsequently, the sewing machine is stopped by measuring the stop time with a timer.

After the sewing machine stops, when a predetermined time by the timer elapses, it is determined that the sewing machine has completely stopped, and generally, the restriction on the rotation of the induction motor is released. .

[0006]

When the restraint on the rotation of the induction motor is released while the sewing machine is stopped, the main shaft of the sewing machine connected to the induction motor via a timing belt or the like and the main shaft of the sewing machine are stopped. Various parts, such as a needle bar and a cloth feed dog, which are operably connected, are movable. For this reason, for example, when the operator turns the manual pulley by touching the manual pulley connected to the main shaft of the sewing machine by mistake, or the cloth presser holding the cloth is released upward and the feed dog is released from the feed dog. The sewing machine main shaft is directly or through an intermediate connecting part, for example, when the feed dog is moved by applying pressure to the feed dog by pressing the cloth from above, or moving the feed dog by pressing the cloth from above. (In the case of the above-mentioned feed dog) It was indirectly rotated, and the rotation phase was out of order. For this reason, there is a problem in that the sewing timing to be performed next is out of order and predetermined sewing cannot be performed.

Therefore, a so-called servo lock technique for restraining the induction motor while the sewing machine is stopped is known. In this case, a so-called encoder for detecting the rotational position provided on the induction motor is used. The direction of rotation of the induction motor is determined based on the signals of the phases A and B obtained by the above, and a forward or reverse rotation command is issued or the voltage applied to the induction motor is changed according to the magnitude of the rotation. The restrained state was maintained.

According to this method, while the restriction of the induction motor can be performed, the encoder is an essential requirement for this control, and the induction motor is specially provided, and since the encoder is relatively expensive, the cost of the control device is reduced. Was expensive.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems. When the sewing machine is stopped, even if an external force is suddenly applied to the main shaft of the sewing machine, the induction motor is securely restrained. It is another object of the present invention to prevent the next sewing operation from being hindered at all, and to provide a control device therefor at low cost.

[0010]

According to one aspect of the present invention, there is provided a sewing machine control device, comprising: an induction motor for driving a sewing machine; An inverter for outputting an AC drive signal for driving the induction motor, start / stop means for instructing start / stop of the sewing machine, rotation detection means for detecting rotation of the sewing machine and outputting a rotation position signal, When a start of the sewing machine is instructed from the start / stop means, a drive for PWM-controlling the inverter so that the output of the inverter has a voltage and a frequency corresponding to the rotation speed command in accordance with the rotation speed command of the sewing machine. A control device for the sewing machine, wherein when the stop of the sewing machine is instructed and the rotation position signal is output from the rotation detecting device, the rotation of the sewing machine is controlled. Characterized by comprising a first control means for outputting a voltage for constraining from the inverters.

In the control device for a sewing machine configured as described above, when a start of the sewing machine is instructed by the start / stop means, the drive control means rotates the output of the inverter in response to the rotation speed command of the sewing machine. The inverter is PWM-controlled so that the voltage and the frequency correspond to the speed command. As a result, an AC drive signal having a voltage and a frequency corresponding to the rotation speed command is output from the inverter, and the induction motor and thus the sewing machine are controlled in accordance with the rotation speed command. During the rotation of the sewing machine, a rotation position signal is sequentially output from the rotation detection means in accordance with the rotation angle.

In the state where the stop of the sewing machine is instructed, for example, when a rotation operation occurs in the sewing machine due to unexpected application of an external force to the main shaft of the sewing machine or the like, the rotation detecting means immediately detects the rotation. Upon detection, a rotation position signal is generated, and the first control means causes the inverter to output a voltage for restricting the rotation of the sewing machine based on the rotation position signal. In this way, since the induction motor is restrained, all the rotating elements on the sewing machine side, such as the main shaft of the sewing machine, operatively connected to the induction motor are restrained.

According to a second aspect of the present invention, there is provided a sewing machine control apparatus according to the first aspect.
In particular, a voltage for restricting rotation of the sewing machine is output based on a rising or falling edge of the rotation position signal having a rectangular wave shape.

As described above, since the output of the voltage for restricting the rotation of the sewing machine is performed based on the rising or falling edge of the rotation position signal having the rectangular wave shape, the restriction control of the induction motor is reliably performed. At the same time, fine control can be performed, and rotation of the sewing machine can be reliably restrained.

According to a third aspect of the present invention, there is provided a sewing machine control device, as shown in FIG. 1, wherein an induction motor for driving the sewing machine and an inverter for outputting an AC drive signal for driving the induction motor. And a start / stop unit for instructing start / stop of the sewing machine; and when a start of the sewing machine is instructed from the start / stop unit, the output of the inverter is changed to the rotation speed command in accordance with the rotation speed command of the sewing machine. Set the inverter to PW so that the voltage and frequency correspond to each other.
A controller for driving the cloth presser for holding the work cloth, wherein the cloth presser driving means outputs a cloth presser driving signal for driving the cloth presser for holding the work cloth; and a state in which the stop of the sewing machine is commanded. And a second control means for causing the inverter to output a voltage for restricting the rotation of the sewing machine when the cloth presser driving signal is output from the cloth presser driving means.

In the control device for a sewing machine configured as described above, when a start of the sewing machine is instructed by the start / stop means, the drive control means rotates the output of the inverter in response to the rotation speed command of the sewing machine. The inverter is PWM-controlled so that the voltage and the frequency correspond to the speed command. As a result, an AC drive signal having a voltage and a frequency corresponding to the rotation speed command is output from the inverter, and the induction motor and thus the sewing machine are controlled in accordance with the rotation speed command.

When the cloth press driving means is operated in a state where the stop of the sewing machine is instructed, a cloth press drive signal is output, and the cloth press attempts to rise from the state of the cloth press by the signal. Or presses down the cloth by lowering it from the ascending position, but the second control means immediately responds to the output of the cloth presser driving signal, and sets a voltage for restricting the rotation of the sewing machine. Output from the inverter. In this way, since the induction motor is restrained, all the rotating elements on the sewing machine side, such as the main shaft of the sewing machine, operatively connected to the induction motor are restrained. Therefore, even if the feed dog is moved by removing or adding the pressing force to the feed dog based on the raising or lowering of the cloth presser, the intermediate interlocking mechanism between the feed dog and the sewing machine spindle is restricted from the sewing machine spindle side. Will be done.

Further, a control device for a sewing machine according to a fourth aspect of the present invention is directed to the control device for a sewing machine according to any one of the first to third aspects, and in particular, a voltage for restraining the rotation of the sewing machine is a direct current. Set to voltage.

As described above, by setting the voltage for restraining the rotation of the sewing machine to a DC voltage, a torque in the reverse direction to the rotation of the induction motor can be applied. Can be assured.

[0020]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a perspective view showing the overall configuration of an industrial lockstitch machine M according to an embodiment to which the present invention is applied. Hereinafter, the configuration of the industrial lockstitch sewing machine M will be described with reference to FIG. 2. However, the industrial lockstitch sewing machine is the same as a general industrial sewing machine, and thus the detailed description thereof is omitted. I do.

As shown in FIG. 2, an industrial lockstitch machine M (hereinafter simply referred to as a sewing machine) M according to the present embodiment is provided with a bed 1 mounted on a work table 10 and a standing end from the right end of the bed 1. And the bed part 1 from the pillar part 2
And an arm portion 3 extending leftward so as to face the arm.

The bed 1 has a feed dog vertical movement mechanism (not shown) for moving the feed dog up and down, a feed dog front and rear movement mechanism (not shown) for moving the feed tooth back and forth, and an upper thread and a lower thread when sewing is completed. And a thread catcher (not shown), etc., for automatically cutting the thread at the same time. The arm 3 has a needle bar drive mechanism for vertically moving a needle bar 4 on which a sewing needle 5 can be mounted at a lower end thereof, and a balance drive mechanism for vertically moving a balance 9 in accordance with the vertical movement of the needle bar 4 ( (Not shown). The vertical movement mechanism and the forward / backward movement mechanism of the feed dog, the needle bar drive mechanism, and the balance drive mechanism are driven by the induction motor 12 via a main shaft (not shown) of the sewing machine in the arm 3.

At the right end of the arm 3, a manual pulley 17 for manually rotating the main shaft of the sewing machine is provided.
A rotation detector 18 capable of generating a detection signal corresponding to the position of the needle bar 4 is provided at a position where the sewing machine main shaft is disposed at the upper end of the pillar 2. The detection signal from the rotation detector 18 is output to a control box 15 storing a control device for controlling the drive of the induction motor 12. Also,
A presser bar 7 is supported on the rear side of the sewing machine frame F on the rear side of the needle bar 4 so as to be vertically movable, and a presser foot 8 as a presser is attached to a lower end of the presser bar 7. .

The rotation detector 18 constitutes the rotation detecting means of the present invention, and is provided in relation to the main shaft of the sewing machine, and detects the rotational position of the main shaft of the sewing machine every moment. As described above, the detection signal corresponding to the upper position or the lower position of the needle bar 4 can be generated at a predetermined rotation angle position. The rotation detector 18 is fixed to the main shaft of the sewing machine, and has a disk-shaped slit disk in which a large number (24 in this embodiment) of slits are circularly arranged at equal intervals; and is fixedly arranged at a fixed position with respect to the slit disk. A photoelectric converter that irradiates the slit with light, receives light passing through the slit, and outputs a position detection signal. Therefore,
When the main shaft of the sewing machine rotates, the slit disk rotates integrally, and the photoelectric converter sequentially detects the slits and outputs a rotation position signal to the control box 15. In response to the rotation position signals when the needle bar 4 is at the highest needle upper position and when the needle bar 4 is at the lowest needle lower position, detection signals ( In this embodiment, a detection signal indicating the needle down position is used as the stop position signal of the sewing machine.

Next, the induction motor 12 is disposed immediately below the work table 10 and is fixed to the work table 11 that supports the work table 10. The control box 15 is fixed below the induction motor 12. A foot pedal 13 for operating the sewing machine is supported at the lower end of the worktable 11 so as to be swingable around a horizontal axis. A lower end of the foot pedal 13 is connected to the foot pedal 13 and a connecting rod extending in the vertical direction. 14 is the workbench 1
1 is connected to a speed command device 20 (see FIG. 3) in a control box 15 attached to the control box 1.

The foot pedal 13 functions as the starting / stopping means and the cloth pressing drive means of the present invention, and includes a horizontal neutral position, a front depressed position where the front side is depressed on the front side with respect to the neutral position, and The speed command device 20 is configured to be capable of swinging between a neutral position and a rear depressed position where the rear side is depressed, and outputs a start signal of the induction motor 12 when the foot pedal 13 is depressed to the front depressed position. By further stepping forward from the state, a speed command signal according to the stepping amount is output, and a start / stop signal is output when stepping into the neutral position, and further, when the first step to the rear stepping position, A cloth presser drive signal for driving the cloth presser bar 7 that supports the cloth presser foot 8 is output, and thread trimming / starting is performed at the second stepping step further from this position to the rear side. It is adapted to output the issue.

Next, the control system of the sewing machine M of this embodiment is as follows.
As shown in the block diagram of FIG.
3, a rotation detector 18, an induction motor 12, a speed command device 20 provided in the control box 15 and connected to the foot pedal 13, a control circuit 21, and a drive circuit 22 for driving the induction motor 12. It is composed of

The control circuit 21 includes a speed command device 20
Input / output interface 2 for inputting a speed command from the motor and a rotation position signal from the rotation detector 18 and outputting a control signal for driving the induction motor 12 to the drive circuit 22
1a, a control amount for controlling the induction motor 12 based on the speed command and the detection signal input from the input / output interface 21a, and a control signal to the drive circuit 22 via the input / output interface 21a according to the calculation result. A one-chip microcomputer (hereinafter, simply referred to as a CPU) 21b including a CPU, a ROM, a RAM, and the like for outputting.
It is composed of

The drive circuit 22 is for supplying a three-phase sine wave alternating current having a different phase to each phase (three phases in this embodiment) of the induction motor 12 in accordance with a control signal from the control circuit 21. And the inverter 30 shown in FIG.
It has.

The control circuit 21 controls each switching element (transistor) provided in the inverter 30.
A well-known PWM control for sequentially turning on and off 31 to 36 by a PWM signal is performed, and the voltage / frequency 3 corresponding to the speed command is supplied from the inverter 30 to each terminal of the induction motor 12.
Output phase AC voltage.

The CPU 21b has such a PWM.
A PWM signal generation circuit for generating a PWM signal for control is also incorporated, but a one-chip microcomputer having such a function is generally commercially available.
Since the configuration is well known, the description of the detailed configuration is omitted. As a matter of course, the PWM signal is generated such that the ON timing of each of the transistors 31 to 36 is delayed by a preset dead time.

As a cloth presser driving means, a dedicated cloth presser switch 40 for outputting a cloth presser driving signal for driving the cloth presser bar 7 instead of or together with the foot pedal 13. May be provided on the front surface of the control box 15, for example. In this case, as shown in FIG. 3, the cloth press switch 40 is connected to the input / output interface 21a of the control circuit 21.

Next, a control process for controlling the sewing machine executed in the control circuit 21 will be described with reference to a flowchart shown in FIG.

As shown in FIG. 4, the control circuit 21 first determines in S10 (S: step) whether or not a start signal is input from the speed command device 20 (start signal ON). If not, the process proceeds to the induction motor restraint control process described later. When the foot pedal 13 is depressed forward and a start signal is input, the process proceeds to S11, where the carrier frequency of the PWM signal generated for inverter control is higher than the audible frequency (for example, tens of kHz). A carrier frequency fc1 for driving the sewing machine is set.

Next, at S12, the speed command device 20
, The output frequency fref of the inverter 30 for driving the sewing machine M at the target speed corresponding to the speed command is calculated, and in S13, the output voltage of the inverter 30 corresponding to the output frequency fref is calculated. Calculate Vref. In the present embodiment, the drive signal output from the inverter 30 is controlled so as to have a preset voltage-frequency characteristic (V / f characteristic). In S13, the output voltage Vref is determined according to the V / f characteristic. Is calculated.

Then, in the subsequent S14, a PW (not shown)
By outputting the frequency fref and the voltage Vref obtained in S12 and S13 to the M signal generation circuit, PW
From the M signal generation circuit, the frequency fre
f. A control signal (PWM signal) for outputting the AC drive signal of the voltage Vref is output, and the process returns to S10.

At this time, the cycle of the PWM signal output from the PWM signal generating circuit is controlled to a cycle (1 / fc1) corresponding to the carrier frequency fc1 set in S11.

Thus, the frequency fref and the voltage V
When ref is output, this time at S15, the speed command device 2
It is determined whether or not a start signal has been input from 0. If the start signal has been input, the process returns to S12 to execute the above processing again.

On the other hand, if it is determined in S15 that the start signal has not been input (start signal OFF), the process proceeds to S1.
6, the induction motor 12, and hence the sewing machine M,
In order to operate at an extremely low stopping speed, a preset constant frequency (minimum) for stopping is set to the output frequency fref of the inverter 30, and the set frequency fref and the voltage Vref corresponding thereto are set to a PWM signal generating circuit. , The induction motor 12 and thus the sewing machine M are operated at the stop speed.

Then, at S17, the rotation detector 18
To determine whether a stop position signal indicating that the needle bar 4 has reached the needle down position, which is the stop position of the sewing machine M, has been input. If the needle bar 4 has not reached the needle down position, the process returns to S16.
Execute the processing of

On the other hand, in S17, when a stop position signal is input from the rotation detector 18 and it is determined that the needle bar 4 has reached the needle down position, the flow shifts to S18 to stop the sewing machine M at that position. Therefore, the command frequency to the PWM signal generation circuit (that is, the output frequency fref from the inverter 30) is set to zero, the output from the inverter 30 is held at the current output, and the timer T stops the sewing machine M during the stop time. Is set, and in S19, a preset carrier frequency fc2 for stopping the sewing machine is set as the carrier frequency of the PWM signal, and the carrier frequency of the PWM signal generated by the PWM signal generation circuit is changed from fc1 to fc2. . Note that the carrier frequency fc2 for stopping the sewing machine is used.
Is set to a frequency in an audible frequency band that is lower than the carrier frequency fc1 for driving the sewing machine.

Then, in the subsequent S20, it is determined whether or not the stop time is measured by the timer T, and
After the sewing machine stops, wait for a predetermined time to elapse, and when the predetermined time elapses, determine that the sewing machine M has completely stopped,
The process returns to S10.

As described above, in the present embodiment, when driving the induction motor 12 to operate the sewing machine M (that is, when executing the processing of S12 to S17), the carrier for driving the sewing machine higher than the audible frequency is used. At the frequency fc1, a PWM signal for controlling the inverter 30 is generated, and when the output from the inverter 30 is kept constant to stop the induction motor 12, that is, the sewing machine M at the needle down position, the PWM signal is generated. As the carrier frequency, a carrier frequency fc2 in an audible frequency band lower than the normal time (fc1) is set, and a PWM signal is generated at the carrier frequency fc2.

For this reason, according to the present embodiment, the torque ripple of the induction motor 12 when the sewing machine stops can be reduced, and the needle position when the sewing machine finally stops can be kept constant.
In addition, during the operation of the sewing machine M, the carrier frequency of the PWM signal is set higher than the audible frequency, so that the electromagnetic noise generated from the induction motor 12 is not heard by the operator, and the electromagnetic noise is reliably prevented. it can.

In the first step S10, the speed command device 2
When the start signal is not input from 0, that is, when the sewing machine is stopped, a control process for restraining the induction motor 12, that is, the sewing machine is performed.

While the sewing machine is stopped, for example, when the operator turns the manual pulley 17 by accidentally touching the manual pulley 17 connected to the main shaft of the sewing machine, or holding the cloth by the presser foot 8. Foot pedal 13 in the state
In the case where the feed dog is moved by the reaction of removing the pressing force from the feed dog by stepping back to the first step or operating the cloth press switch 40 to release the presser foot 8 upward from the cloth, etc. The main shaft of the sewing machine is rotated directly or indirectly via an intermediate coupling mechanism of the feed dog.

However, at this time, in the former case (when the main shaft of the sewing machine is turned by the manual pulley 17), the rotation detector 18 detects the first slit of the rotation in S21 in FIG. When the position signal, that is, the rising edge of the encoder signal is detected (S21, YES), in the next S22, as shown in the timing chart of FIG. A DC voltage V1 is applied to the induction motor 12 via the inverter 30, and a torque is applied in a direction opposite to the rotation of the induction motor 12. In this state, it is determined whether or not the output time T1 has elapsed (S23). If it is within the output time T1 (S23, NO), the application of the DC voltage is continued,
If the output time T1 has elapsed (S23, YES), the next S
At 24, the output voltage is set to V0 and the application of the DC voltage is stopped (the DC voltage is reduced from V1 to V0. This V0 is set to a DC voltage that is about 50 to 70% lower than V1). .

Then, the process returns to the first step S10, and again the step S2
At 1, the detection of the edge of the encoder signal is determined. Then, when the falling edge of the first encoder signal is detected (S21, YES), the same processing as described above is executed, and the processing based on the first encoder signal ends.

The above-described series of processing is actually performed instantaneously, and the restriction control on the rotation of the induction motor 12 is performed. Then, when the rising edge of the encoder signal corresponding to the next slit following the first slit is detected by the rotation detector 18, a series of processing similar to the above is repeated.

In this manner, the restraining action on the rotation of the induction motor 12 is repeatedly executed within an instant.
The induction motor 12, and consequently the main shaft of the sewing machine and its interlocking system, are restrained while being hardly rotatable.

On the other hand, in the latter case, that is, while the cloth is being held down by the cloth presser foot 8, the worker inadvertently steps on the foot pedal 13 to the first step, or switches the cloth press-up switch 40. When the cloth presser foot 8 is to be released upward from the cloth by operating, the restraining process of the induction motor 12 is performed as described below.

That is, at the moment of the switch operation, it is determined in S10 of FIG. 4 that the signal is not an activation signal (S1).
0, NO), it is determined that the edge is not the edge of the encoder signal also in the subsequent S21 (S21, NO), and if the rising edge of the presser foot driving signal is detected in S25 (S25, YES), in the next S26, As shown in the timing chart of FIG. 6, the output time T1 of the DC voltage is set in the timer T almost in the same manner as in the case of the encoder signal, and the DC voltage V1 is applied to the induction motor 12 through the inverter 30. , Its induction motor 1
Apply a torque in the opposite direction to the rotation of 2. In this state, it is determined whether the output time T1 has elapsed (S27). If the output time T1 is within the output time T1 (S27, N
O) When the application of the DC voltage is continued and the output time T1 has elapsed (S27, YES), in the next S28, the output voltage is set to V0 and the application of the DC voltage is stopped (DC voltage). From V1 to V0, which is V1
Is set to a DC voltage which is about 50 to 70% lower than that of the DC voltage).

Then, the process returns to the first step S10, and again the step S2
In step S25 after the processing of step 1, the detection of the edge of the cloth presser drive signal is determined. When the falling edge of the signal is detected (S25, YES), the same processing as described above is executed and the processing ends. In this manner, since the restraining action on the rotation of the induction motor 12 is executed instantaneously, the feed dog is released by releasing the cloth presser foot 8 upward from the cloth, and the feed dog is rebounded by removing the pressing force from the feed dog. Even if it is moved, the main shaft of the sewing machine is also constrained by the constrained induction motor, so that the movement of the feed dog is indirectly transmitted to the main shaft of the sewing machine via the intermediate coupling mechanism, leading to rotation. There is no such thing.

As described above, even when an unexpected external force is applied directly or indirectly to the main shaft of the sewing machine while the sewing machine is stopped, the induction motor, and furthermore, the main shaft of the sewing machine and its interlocking system cannot be rotated. Since the main shaft can be restrained, the rotation of the main shaft of the sewing machine does not deviate the drive timing of the needle or the like, thereby hindering the next sewing. In addition, since the constraint control of the induction motor is executed by using the encoder signal of the existing rotation detector provided in the sewing machine, the constraint control can be realized by an inexpensive device.

The processing from S21 to S24 functions as the first control means of the present invention, and the processing from S25 to S2
The processing up to 8 functions as the second control means of the present invention.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and can take various forms. For example, in the above embodiment, the case where the present invention is applied to the industrial lockstitch sewing machine M has been described. However, the present invention is applicable to any sewing machine that includes an induction motor as a drive motor and controls the induction motor using an inverter. It can be applied to any model.

[0058]

As described in detail above, claim 1 of the present invention
As shown in FIG. 1, the control device for a sewing machine according to the present invention is directed to a control device for a sewing machine including an induction motor, an inverter, a start / stop unit, a rotation detection unit, and a drive control unit. In particular, in a state where the stop of the sewing machine is instructed, a first control means for outputting a voltage for restricting the rotation of the sewing machine from the inverter when a rotation position signal is output from the rotation detection means is provided. Therefore, in the stopped state of the sewing machine, for example, even if a rotation operation occurs on the sewing machine due to sudden application of an external force to the main shaft of the sewing machine or the like, the rotation detection means of the sewing machine immediately detects the rotation and rotates. Generating a position signal, and using the rotation position signal, the first control means causes the inverter to output a voltage for restricting rotation of the sewing machine;
In order to restrain the induction motor, it is possible to restrain all rotating elements on the sewing machine side, for example, the main shaft of the sewing machine, which are operatively connected to the induction motor.

Therefore, the rotation of the main shaft of the sewing machine does not cause the drive timing of the needle or the like to be out of order, so that the next sewing operation is not hindered. In addition, since the restraint control of the induction motor is performed using the rotation detection signal of the existing rotation detecting means provided in the sewing machine, the restraint control can be realized by an inexpensive device.

According to the sewing machine control device of the second aspect, the voltage for restraining the rotation of the sewing machine is particularly rectangular in the control device of the sewing machine of the first aspect. Since the output is performed based on the rising or falling edge of the rotation position signal, the restraint control of the induction motor is ensured and the control can be finely controlled, and the rotation of the sewing machine is restrained extremely quickly and reliably. can do.

According to a third aspect of the present invention, there is provided a sewing machine control device including an induction motor, an inverter, a start / stop device, and a drive control device. A cloth presser driving means for outputting a cloth presser drive signal for driving the cloth presser that presses the cloth;
Second control means for outputting a voltage for restricting rotation of the sewing machine from the inverter when a cloth presser driving signal is output from the cloth presser driving means in a state where the stop of the sewing machine is instructed. Therefore, in the stopped state of the sewing machine, even when the cloth presser driving means is inadvertently operated, when the cloth presser driving signal is output, the cloth presser attempts to rise from the state of the cloth presser by the signal. Alternatively, the second control means immediately responds to the cloth pressing drive signal by lowering the cloth from the ascending position, and outputs a voltage for restricting the rotation of the sewing machine from the inverter. In order to output and restrain the induction motor, all the rotating elements on the sewing machine side, such as the main shaft of the sewing machine, operatively connected to the induction motor must be restrained. It can be.

As described above, since the restraining action on the rotation of the induction motor is executed instantaneously, the feed dog is moved by the recoil in which the pressing force is removed from the feed dog by releasing the cloth presser upward from the cloth. However, since the main shaft of the sewing machine is also constrained by the constrained induction motor, the movement of the feed dog is indirectly transmitted to the main shaft of the sewing machine via the intermediate coupling mechanism, leading to rotation. There is nothing.

Further, according to the control device for a sewing machine according to the fourth aspect, the control device for the sewing machine according to any one of the first to third aspects, in particular, a voltage for restricting the rotation of the sewing machine. Is set to a DC voltage, so that a torque in the opposite direction to the rotation of the induction motor can be applied,
The restraint control can be further reliably performed without variation.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing the present invention.

FIG. 2 is a perspective view illustrating a schematic configuration of an industrial lockstitch sewing machine according to the present embodiment.

FIG. 3 is a block diagram illustrating a configuration of a control system of the sewing machine according to the embodiment;

FIG. 4 is a flowchart showing various control processes of the sewing machine.

FIG. 5 is a circuit diagram showing an example of an inverter used when driving a sewing machine motor (three-phase induction motor).

FIG. 6 is a timing chart showing a relationship between a signal and a voltage used for restraint control of the induction motor.

[Explanation of symbols]

 M sewing machine (industrial lockstitch sewing machine) 8 cloth presser foot 12 induction motor 13 foot pedal 15 control box 18 rotation detector 20 speed command device 21 control circuit 21b CPU 22 drive circuit 30 inverter 40 cloth lift switch

Claims (4)

[Claims] 1. An induction motor for driving a sewing machine, an inverter for outputting an AC drive signal for driving the induction motor, start / stop means for instructing start / stop of the sewing machine, and rotation of the sewing machine. A rotation detection unit that detects and outputs a rotation position signal, and when a start of the sewing machine is commanded from the start / stop unit,
A control device for a sewing machine, comprising: a drive control unit that performs PWM control on the inverter so that an output of the inverter has a voltage and a frequency corresponding to the rotation speed command in accordance with the rotation speed command of the sewing machine. A first control means for outputting, from the inverter, a voltage for restricting the rotation of the sewing machine when a rotation position signal is output from the rotation detection means in a state where the stop of the rotation is commanded. Sewing machine control device. 2. The sewing machine control according to claim 1, wherein the voltage for restricting the rotation of the sewing machine is output based on a rising or falling edge of the rotation position signal having a rectangular wave shape. apparatus. 3. An induction motor for driving a sewing machine; an inverter for outputting an AC drive signal for driving the induction motor; start / stop means for instructing start / stop of the sewing machine; When the start of the sewing machine is commanded by the means,
A control device for a sewing machine, comprising: a drive control unit that performs PWM control on the inverter so that an output of the inverter has a voltage and a frequency corresponding to the rotation speed command in accordance with the rotation speed command of the sewing machine. A cloth presser driving means for outputting a cloth presser driving signal for driving the cloth presser for holding the sewing machine; and a sewing machine when the cloth presser driving signal is output from the cloth presser driving means in a state where the stop of the sewing machine is instructed. And a second control means for causing the inverter to output a voltage for restricting the rotation of the sewing machine. 4. The sewing machine control device according to claim 1, wherein the voltage for restricting the rotation of the sewing machine is a DC voltage.