JP2007159708A - Motor control device of sewing machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor control device of a sewing machine, capable of preventing the loss of synchronism of a pulse motor even if the electric power fed to a DC motor and the pulse motor exceeds the rating of the power supply. <P>SOLUTION: The motor control device 50 comprises a power supply unit 55 for feeding the electric power to the DC motor 41 for driving a sewing needle 14 and the pulse motor 42 for driving an embroidery frame attaching part 18, a pulse motor driver 52 for driving the pulse motor 42, a transistor Tr for switching the power supply unit 55 and the DC motor 41, and a CPU 51. The CPU 51 functions as a PWM control means for driving the DC motor 41 by the PWM control, a clocking means for clocking the time when the voltage applied to the DC motor 41 by the power supply unit 55 is a first threshold α or lower and a stopping means for stopping the PWM control of the DC motor 41 when the clocking time exceeds prescribed time A. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a motor control device for a sewing machine in which a power source of a DC motor that drives a sewing needle is in common with a power source of a pulse motor that drives a cloth feeding unit.

  The sewing machine is provided with a motor for driving the sewing needle, and the sewing needle moves up and down by controlling the motor with a control device (see, for example, Patent Document 1, Patent Document 2, and Patent Document 3). Further, the sewing machine is provided with a cloth feeding portion for feeding the cloth, and a motor for driving the cloth feeding portion is provided separately from a motor for driving the sewing needle. Generally, a DC motor is used as a motor that moves the sewing needle up and down. On the other hand, a pulse motor is used as a motor for driving the cloth feed section, so that the cloth can be positioned with high accuracy.

In a conventional sewing machine, a DC motor power source and a pulse motor power source are common. As in the conventional motor control device of FIG. 5, when the rotational speed of the DC motor 141 is detected by the encoder 156 and the CPU 151 outputs a PWM (Pulse Width Modulation) signal to the switching transistor 153 according to the detected rotational speed, the switching transistor 153 By performing switching according to the duty ratio of the PWM control signal, the rotational speed of the DC motor 141 is controlled, and the sewing needle moves up and down. Further, when the CPU 151 outputs a control signal to the pulse motor driver 152 at the timing when the sewing needle is raised, the pulse motor 142 rotates by an angle corresponding to the control signal, and thereby the cloth is fed by a predetermined distance.
JP 2001-38086 A JP 2001-38087 A JP 2001-46773 A

By the way, when the DC motor 141 is driven by PWM control, the load torque and the current value flowing from the power supply unit 155 to the DC motor 141 are in a proportional relationship. Therefore, when a load is applied from the sewing needle to the DC motor 141 during the operation of the DC motor 141, the current supplied to the DC motor 141 increases. At this time, the power supply unit 155 can stabilize because there is an output impedance when the stabilized power supply is created by rectifying using a commercial transformer and when the stabilized power supply is created by switching the primary power. When the allowable current is exceeded, the voltage applied from the power supply unit 155 to the DC motor 141 gradually decreases, and the voltage applied to the pulse motor driver 152 also decreases. Therefore, when the voltage applied to the pulse motor driver 52 is lower than the operable voltage of the pulse motor 142, the pulse motor 142 steps out.
In order to prevent the step-out of the pulse motor 142, even if the power supply unit 155 has a high output or the power supply of the DC motor 141 and the power supply of the pulse motor 142 are separated, the cost increases.

  Therefore, the present invention has been made to solve the above-described problems, and it is assumed that the power supplied to the DC motor and the pulse motor using a common power source for the DC motor and the pulse motor exceeds the rating of the power source. Another object of the present invention is to provide a sewing machine motor control device capable of preventing the step-out of the pulse motor.

  In order to solve the above-described problems, the invention according to claim 1 is configured to perform PWM control on a DC motor that drives a sewing needle and a power supply unit that supplies power to a pulse motor that drives a cloth feed unit, and the DC motor. PWM control means for driving the DC motor with the power of the power supply unit, time measuring means for measuring the time during which the voltage applied to the DC motor by the power supply unit is below a predetermined threshold, and the time measuring means And a stop means for stopping the PWM control by the PWM control means when a predetermined time has elapsed.

  According to the first aspect of the present invention, when a load is applied to the DC motor during the operation of the DC motor by PWM control and the current supplied from the power supply unit to the DC motor rises and exceeds the rated current of the power supply unit, the power supply The voltage applied from the unit to the DC motor decreases. Then, when the voltage applied from the power supply unit to the DC motor falls below a predetermined threshold value and this state continues for a predetermined time, the PWM control of the DC motor is interrupted by the stopping means. Therefore, the DC motor is stopped and the step-out of the pulse motor can be prevented.

  The invention according to claim 2 is characterized in that the predetermined threshold and the predetermined time are different in a sewing mode and an automatic bobbin winding mode of a sewing machine.

  According to the invention described in claim 2, when the driving of the DC motor is stopped in the automatic bobbin winding mode, the predetermined winding amount cannot be obtained, and the operator must redo all the operations again. Predetermined threshold value and predetermined time are different between the sewing mode and the automatic bobbin winding mode, and it is possible to redo such work by lowering the standard for stopping the driving of the DC motor in the automatic bobbin winding mode than the sewing mode. Lower.

According to the present invention, the step-out of the pulse motor can be prevented without increasing the rating of the power supply unit and the power supply of the pulse motor and the DC motor are not separated, and the manufacturing cost of the sewing machine can be reduced. be able to.
Further, the step-out of the pulse motor can be prevented, so that the lowering position of the sewing needle with respect to the cloth does not shift and the sewing failure can be prevented.

  The best mode for carrying out the present invention will be described below with reference to the drawings. However, although various technically preferable limitations for implementing the present invention are given to the embodiments described below, the scope of the invention is not limited to the following embodiments and illustrated examples.

  As shown in FIGS. 1 and 2, the sewing machine bed 11 of the embroidery sewing machine 1 is positioned at the lower part, the sewing machine body 12 is raised upward from one end of the sewing machine bed 11, and the sewing machine arm 13 is attached to the sewing machine body 12. It extends along the sewing machine bed 11 from above.

  A sewing needle 14 and a presser foot 16 are provided on the sewing machine head 13a on the tip side of the sewing machine arm 13 so as to extend downward, and the sewing needle 14 can be moved up and down. The sewing needle 14 is connected to the upper shaft via a needle bar, a crank mechanism, and the like, and the upper shaft is provided in the sewing machine arm 13. The upper shaft is connected to a DC motor 41 through a transmission mechanism, and the sewing needle 14 moves up and down by the DC motor 41.

  Below the sewing needle 14, an embroidery frame mounting portion 18 as a cloth feeding portion is provided on the sewing machine bed 11, and the embroidery frame 17 can be attached to and detached from the embroidery frame mounting portion 18. The cloth is stretched along a plane perpendicular to the sewing needle 14 by the embroidery frame 17 attached to the sewing needle 14. The embroidery frame mounting portion 18 is provided to be movable in the front-rear direction (Y direction) and to be movable in the left-right direction (X direction). The embroidery frame mounting portion 18 is connected to the pulse motor 42 via the X-direction transmission mechanism, and the cloth is moved in the left-right direction together with the embroidery frame mounting portion 18 and the embroidery frame 17 by the pulse motor 42. Further, the embroidery frame mounting portion 18 is connected to the pulse motor 43 via the Y-direction transmission mechanism, and the cloth is moved in the front-rear direction together with the embroidery frame mounting portion 18 and the embroidery frame 17 by the pulse motor 43.

  Below the sewing needle 14, a shuttle device is provided in the sewing machine bed 11. The shuttle device is connected to the DC motor 41 via the lower shaft and the transmission mechanism, and the shuttle device is driven by the DC motor 41.

  A bobbin is provided in the hook device, and a bobbin thread is wound around the bobbin. A bobbin thread winding device is provided in the sewing machine bed 11, and the bobbin thread winding device is connected to the DC motor 41 via a transmission mechanism, a clutch, and the like. When the bobbin in the bobbin runs out, the bobbin winding device and the DC motor 41 are connected by a clutch. When the bobbin winding device is driven by the DC motor 41, the bobbin winding device winds the bobbin thread around the bobbin. During sewing, the lower thread winding device and the DC motor 41 are cut.

  As shown in FIG. 2, the motor controller 50 of the embroidery sewing machine 1 includes a DC motor 41, pulse motors 42 and 43, a CPU 51, pulse motor drivers 52 and 53, a storage unit 54, a power supply unit 55, Encoders 56 and 57, resistors R1 and R2, and a transistor Tr are provided.

  The power supply unit 55 is used as a common power supply for the DC motor 41, the pulse motor 42, and the pulse motor 43, and supplies power to the DC motor 41, the pulse motor driver 52, and the pulse motor driver 53.

  The transistor Tr is connected to the OUT port 51b of the CPU 51, and performs switching between the DC motor 41 and the power supply unit 55 in accordance with a control signal from the CPU 51.

  The pulse motor driver 52 is connected to the OUT port 51b of the CPU 51, and drives the pulse motor 42 according to the control signal of the CPU 51 by the power of the power supply unit 55. The pulse motor driver 53 is connected to the OUT port 51b of the CPU 51, and drives the pulse motor driver 53 according to the control signal by the power of the power supply unit 55 of the CPU 51.

  The voltage applied to the DC motor 41, the pulse motor driver 52, and the pulse motor driver 53 by the power supply unit 55 is input to the A / D port 51c of the CPU 51 in a state where the voltages are divided by the resistors R1 and R2. The A / D port 51c is provided with an A / D converter, and the input voltage is sampled and converted into a digital signal by the A / D converter.

  The encoder 56 detects the rotational speed of the DC motor 41, and outputs the detected rotational speed to the IN port 51 a of the CPU 51. Specifically, every time the DC motor 41 rotates by a predetermined angle (for example, 1 °), a pulse signal is input from the encoder 56 to the CPU 51, whereby the rotational speed of the DC motor 41 is detected.

  The encoder 57 detects the angle of the upper shaft corresponding to the position of the sewing needle 14 and outputs the detected angle to the IN port 51 a of the CPU 51. Specifically, a pulse signal is input from the encoder 57 to the CPU 51 every time the upper shaft reaches a predetermined rotation angle, whereby the position of the sewing needle 14 is detected.

  The CPU 51 functions as a PWM control unit that feeds back the rotational speed input from the encoder 56 and performs PWM control of the DC motor 41 so that the rotational speed of the DC motor 41 is constant. That is, the CPU 51 outputs a PWM control signal having a duty ratio according to the rotational speed input from the encoder 56 to the transistor Tr, and the transistor Tr performs switching according to the duty ratio, so that the rotational speed of the DC motor 41 is constant. It is controlled to become.

  Assuming that the period during which the sewing needle 14 moves up and down once when the DC motor 41 is driven by the PWM control of the CPU 51 is one cycle, the storage unit 54 stores the pulse motor 42 in each cycle as shown in FIG. Is stored as a data string in order from the first cycle. The rotation angle (which corresponds to the feed distance of the embroidery frame mounting portion 18 in the front-rear direction) is to be rotated. Further, the storage unit 54 stores the rotation angle (which corresponds to the feed distance of the embroidery frame mounting unit 18 in the left-right direction) to rotate the pulse motor 43 in each cycle as a data string in order from the first cycle. Yes. The CPU 51 functions as a feed control unit that reads the rotation angle from the storage unit 54 for each cycle of the sewing needle 14 and rotates the pulse motors 42 and 43 by the read rotation angle. That is, when the CPU 51 outputs a control signal according to the rotation angle read from the storage unit 54 to the pulse motor drivers 52 and 53, the pulse motors 42 and 43 are rotated by the pulse motor drivers 52 and 53, respectively. Only driven. In each period, the timing at which the CPU 51 reads the rotation angle from the storage unit 54 and the timing at which the CPU 51 outputs a control signal to the pulse motor drivers 52 and 53 are the rotation angle detected by the encoder 57, that is, the sewing needle 14 It depends on the position of. For example, a pulse signal is input from the encoder 57 to the CPU 51 at the timing when the sewing needle 14 is inserted into the cloth, and the CPU 51 reads the rotation angle from the storage unit 54 at that timing, and the encoder 57 sends the CPU 51 to the CPU 51 at a timing when the sewing needle 14 comes off the cloth. A pulse signal is input, and a control signal according to the rotation angle read by the CPU 51 at that timing is output to the pulse motor drivers 52 and 53.

  In the automatic bobbin winding mode, that is, when the power of the DC motor 41 is connected by the clutch and transmitted to the bobbin winding device, the CPU 51 does not rotate the pulse motors 42 and 43 as described above. On the other hand, in the embroidery sewing mode, that is, when the power of the DC motor 41 is interrupted by the clutch and is not transmitted to the lower thread winding device, the CPU 51 rotates the pulse motors 42 and 43 as described above.

When the DC motor 41 is driven by the PWM control of the CPU 51 and in the embroidery sewing mode, the CPU 51 determines that the voltage applied to the DC motor 41, the pulse motor driver 52, and the pulse motor driver 53 is less than or equal to the first threshold value α. It functions as a time measuring means for measuring a certain time. When the predetermined time A has elapsed, the CPU 51 functions as a stopping unit that stops the PWM control and interrupts the driving of the DC motor 41. As a result of the function of the stopping means of the CPU 51, no pulse signal is input from the encoder 57 to the CPU 51, so that the driving of the pulse motors 42 and 43 by the CPU 51 is also interrupted. Here, when the state where the sewing needle 14 is stuck in the cloth is detected by the encoder 57, that is, when the CPU 51 reads the rotation angle from the storage unit 54, the CPU 51 delays the stop of the PWM control, After the control signal according to the read rotation angle is output to the pulse motor drivers 52 and 53, the PWM control is stopped.
The first threshold value α is preferably equal to or higher than a voltage at which the pulse motor 142 can operate.

  In the automatic bobbin winding mode when the DC motor 41 is driven by PWM control of the CPU 51, the CPU 51 determines that the voltage applied to the DC motor 41, the pulse motor driver 52, and the pulse motor driver 53 is the second threshold value β ( However, it functions as a time measuring means for measuring the time when the first threshold value α> the second threshold value β). Then, when the predetermined time B has elapsed, the CPU 51 functions as a stopping unit that stops the PWM control and interrupts the driving of the DC motor 41. The predetermined time B is longer than the predetermined time A.

  The functions of the CPU 51 as described above are realized by the CPU 51 executing a program stored in the storage unit 54.

Operations of the sewing machine 1 and the motor control device 50 will be described.
First, the embroidery sewing mode will be described. The CPU 51 drives the DC motor 41 by PWM control, so that the DC motor 41 is rotated by the power of the power supply unit 55 and the rotation speed of the DC motor 41 is kept constant. As the DC motor 41 rotates, the sewing needle 14 moves up and down and the shuttle device is driven.

  When the sewing needle 14 descends and the sewing needle 14 pierces the cloth, a pulse signal is input from the encoder 57 to the CPU 51, whereby the CPU 51 reads the rotation angle from the storage unit 54. When the sewing needle 14 rises and the sewing needle 14 comes off the cloth, a pulse signal is input from the encoder 57 to the CPU 51, and a control signal according to the rotation angle read by the CPU 51 is output to the pulse motor drivers 52 and 53. . Thus, the embroidery frame 17, the embroidery frame mounting portion 18, and the cloth are moved in the front-rear direction by the pulse motor 42 and left and right by the pulse motor 43 between the time when the sewing needle 14 comes out of the cloth and the next time it is inserted into the cloth. Moved in the direction.

  As described above, when the sewing needle 14 is repeatedly moved up and down and the cloth is repeatedly moved when the sewing needle 14 is raised, the seam is applied to the cloth by the cooperation of the sewing needle 14 and the shuttle device.

When the DC motor 41 is driven by PWM control of the CPU 51, the voltage applied to the DC motor 41, the pulse motor driver 52, and the pulse motor driver 53 is compared with the first threshold value α by the CPU 51. Here, it is assumed that a load is applied to the sewing needle 14 due to cloth resistance, thread tension, and the like while the sewing needle 14 is moving up and down. When the DC motor 41 is driven by the PWM control of the CPU 51, the load torque and the value of the current flowing through the DC motor 41 are in a proportional relationship. Therefore, when the load of the sewing needle 14 begins to increase suddenly, as shown in FIG. When the drive current of the DC motor 41 rises and the drive current exceeds the rating of the power supply unit 55, the voltage applied to the DC motor 41, the pulse motor driver 52, and the pulse motor driver 53 by the power supply unit 55 is lowered. Then, the CPU 51 measures the time when the voltage applied to the DC motor 41, the pulse motor driver 52, and the pulse motor driver 53 is equal to or less than the first threshold value α, and when the measured time exceeds a predetermined time A, the CPU 51 PWM control is stopped and driving of the DC motor 41 is interrupted. Here, when the measured time has elapsed after the rotation angle is read from the storage unit 54 by the CPU 51, the CPU 51 waits to output a control signal according to the rotation angle to the pulse motor drivers 52 and 53. The PWM control of the DC motor 41 is stopped. When the DC motor 41 stops, no signal is input from the encoder 57 to the CPU 51, so that the CPU 51 does not drive the pulse motors 42 and 43 thereafter. Further, when the DC motor 41 is stopped, the power of the power supply unit 55 falls below the rated power, and the step-out of the pulse motors 42 and 43 can be prevented.
Note that the voltage exceeds the first threshold value α before the time during which the voltage applied to the DC motor 41, the pulse motor driver 52, and the pulse motor driver 53 is equal to or less than the first threshold value α has passed the predetermined time A. Then, the CPU 51 ends timing.

Next, the automatic bobbin winding mode will be described.
As in the embroidery sewing mode, the CPU 51 drives the DC motor 41 by PWM control, so that the DC motor 41 rotates. Accordingly, the lower thread winding device is driven by the DC motor 41, and the lower thread is wound around the bobbin in the shuttle device. At this time, the voltage applied to the DC motor 41, the pulse motor driver 52, and the pulse motor driver 53 is compared with the second threshold value β by the CPU 51. As a result of comparison, when the voltage applied to the DC motor 41, the pulse motor driver 52, and the pulse motor driver 53 is equal to or lower than the second threshold value β, the voltage is applied to the DC motor 41, the pulse motor driver 52, and the pulse motor driver 53. The CPU 51 measures the time during which the applied voltage is equal to or lower than the second threshold value β. When the measured time exceeds the predetermined time B, the CPU 51 stops the PWM control and interrupts the driving of the DC motor 41. Therefore, the DC motor 41 is stopped, the power of the power supply unit 55 is lowered to the rated power or less, and the step-out of the pulse motors 42 and 43 can be prevented.

  On the other hand, if the voltage applied to the DC motor 41, the pulse motor driver 52, and the pulse motor driver 53 exceeds the second threshold value β before the predetermined time B elapses, the CPU 51 ends the time measurement.

  In the automatic bobbin winding mode, the pulse motors 42 and 43 are not driven by the CPU 51.

  As described above, according to the present embodiment, when the load applied to the DC motor 41 increases and exceeds the rated power of the power supply unit 55 and the state continues for a predetermined time A or a predetermined time B, the DC motor 41 PWM control is interrupted. Therefore, the DC motor 41 is stopped and the step-out of the pulse motors 42 and 43 can be prevented. Since the step-out of the pulse motors 42 and 43 can be prevented without increasing the rating of the power supply unit 55 and without separately supplying power to the pulse motor 42 and the DC motor 41, the manufacturing cost of the sewing machine 1 can be prevented. Can be suppressed. In addition, since the step-out of the pulse motors 42 and 43 can be prevented, the lowering position of the sewing needle 14 with respect to the cloth does not occur, and sewing defects can be prevented.

It is a front view of the embroidery sewing machine provided with the motor control apparatus in the embodiment of the present invention. It is a block diagram of a motor control device in an embodiment of the present invention. It is the figure which showed the data sequence of the rotation angle of each period memorize | stored in the memory | storage part. It is the chart which showed the change of the voltage and electric current which are applied to a DC motor by a power unit. It is a block diagram of the conventional motor control apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sewing machine 14 Sewing needle 18 Embroidery frame mounting part 41 DC motor 42, 43 Pulse motor 50 Motor controller 51 CPU
52, 53 Pulse motor driver 54 Memory unit 55 Power supply unit Tr Transistor R1, R2 Resistance

Claims (2)

A power supply unit for supplying electric power to a DC motor for driving the sewing needle and a pulse motor for driving the cloth feed unit;
PWM control means for PWM controlling the DC motor, and driving the DC motor with power from the power supply unit;
Clocking means for timing the time during which the voltage applied to the DC motor by the power supply unit is below a predetermined threshold;
A sewing machine motor control device comprising: a stopping unit that stops PWM control by the PWM control unit when a predetermined time has elapsed from the time measured by the time measuring unit.   The sewing machine motor control device according to claim 1, wherein the predetermined threshold and the predetermined time are different in a sewing mode and an automatic bobbin winding mode of the sewing machine.

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