KR870001528B1 - Driving device of sewing machine - Google Patents

Abstract

Sewing machine drive device comprises a brushless drive motor which has magnets in its rotor and in which the phase of current flowing in the stator winding is varied depending on the rotor position; a speed detector which detects the rotary speed of the sewing machine spindle or the motor; a detector which detects the needle position; apedal for producing command signals and a stop command signal; a speed controller which compares the speed detector output with speed command signals proportional to pedal displacement.

Description

Sewing machine drive

1 is a perspective view showing a configuration example of a general sewing machine and a sewing machine driving device.

2 is a cross-sectional view showing the structure of a conventional drive motor.

3 is a cross-sectional view showing the structure of the drive motor unit of the present invention.

4 is a circuit diagram showing a driving unit of the present invention.

5 is a time difference art showing the operation of the distribution circuit of the present invention.

6 is a block diagram showing the overall operation of the present invention.

7 is a time difference art for supplementing the operation of FIG.

* Explanation of symbols for main parts of the drawings

24: stator winding 25: permanent magnet

29: magnet for commutation sensor 33: pedal

34: speed commander 35: position commander

38: PWM circuit 42: commutation sensor

45: speed detector 47: position detector

The present invention relates to a sewing machine drive device, in particular a variable speed operation including a drive stop of the sewing machine and a sewing machine drive device to perform a fixed position stop of the sewing machine needle.

In particular, an industrial sewing machine and its driving apparatus generally have the configuration shown in FIG. 1, (1) a sewing machine head, (2) a detector for detecting the speed and needle position of the sewing machine, (3) a drive motor, (4) receives signals from the detector (2) and a pedal A control unit for controlling the drive motor 3, the solenoid of the sewing machine, and the like, 5 denotes a sewing machine table, and 6 denotes a pedal.

The conventional structure of this drive electric motor 3 has the structure shown in FIG. This motor has a structure in which an induction motor, a clutch and a brake mechanism are integrated. The drive shaft 7 of the induction motor, the flywheel 8 and the clutch friction plate 9 coupled thereto continuously rotate to collect rotational energy in the flywheel 8. The clutch movable disk 10 and the brake movable disk 11 can slide in the axial direction on the spline 13 pressed into the output shaft 12, and the linings 14 and 15 are respectively bonded. When the clutch electromagnet 16 is excited now, the magnetic flux 17 is generated, and the clutch movable disk 10 moves to the left side, and the lining 14 is press-contacted to the clutch friction disc 9 which is continuously rotating. Thus, the rotational force of the flywheel 8 is transmitted to the output shaft 12 via the spline 13. Next, when the brake electromagnet 18 is excited, the brake movable disc 11 moves to the right, and the lining 15 is pressed against the brake friction disc 20 fixed to the bracket 19 to output the shaft 12. Stops rapidly. The rotational force of the output shaft 12 is normally transmitted to the sewing machine head 1 via the belt. The speed control of the sewing machine is performed by generating a half-clutch state by pyriding back the speed signal detected by the detector 2 and adding or subtracting an excitation current of the clutch electromagnet 16. The stop of the sewing machine needle is performed by exciting the brake electromagnet 18 by the needle position signal of the detector 2.

In recent years, due to the high performance of industrial sewing machines and the development of automatic sewing machines, this driving motor has been emphasized not only as a driving stop but also as a strong time driving at a medium speed. In the conventional electric motor shown in FIG. 2, since the lining 14 is slid and used in the half-clutch state as mentioned above at the time of intermediate | middle speed operation, it was not enough about the life by promoting wear of the lining. This lining is generally made of cork as the main component by adhesives such as urethane and impregnated oil, and methods such as applying grease containing physium sulfide bisulfide on sliding surfaces have been put to practical use, and considerable long-life cotton is achieved. However, there have been limitations such as requiring regular grease application or replacement of linings. In addition, since the reactance of the electromagnet is relatively large, the stability of the speed is poor on the clutch side, and the stop position of the sewing machine needle tends to be inconsistent due to the delay of the excitation current.

In order to improve the service life, a method in which a friction clutch is replaced with an eddy current clutch has been proposed and has been put into practical use in part. This method is obviously improved with respect to the clutch life as described above in order to transmit the rotational force of the flywheel to the output shaft as a non-contact, but since the brake part uses the same friction type brake as the conventional brake part because sufficient braking force is not obtained. There was no progress in life. In addition, in order to prevent thermal deformation of the eddy current generating unit, the excitation current must be limited, and therefore, sufficient torque cannot be obtained.

In addition, these conventional methods consume unnecessary power because the drive motor must be rotated at all times regardless of driving or stopping of the sewing machine. Normally, the operating time of a sewing machine is 20 to 30%, and the remaining 70 to 80% of the electric motor is idle, and about 100 W of electric power is wasted in a single-phase 400 W electric motor.

In addition, since the flywheel 8 installed on the drive motor needs to increase the rotational energy, its outer diameter has to be increased and its weight is heavy, which hinders the miniaturization and weight reduction of the drive motor.

In order to eliminate the above-mentioned drawbacks, the present invention eliminates the friction part and extends the lifespan, stops the electric motor when the sewing machine stops, and saves energy. In this way, the clutch and brake unit and flywheel are abolished to reduce the size and weight.

The sewing machine driving apparatus of the present invention includes a so-called brushless electric motor having a permanent magnet in the rotor and switching the energization phase of the stator winding according to the position of the rotor, a detector of the speed and needle position of the sewing machine, and those It is composed of a control mechanism, to provide a novel sewing machine drive device that solves the conventional drawbacks.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

3 is a structural sectional view of the drive motor. In FIG. 3, 21 is a base attached to a sewing machine table, 22 is a frame, 23 is a stator iron core, 24 is a stator winding, 25 is a permanent magnet, and a rotor yoke ( 26). Reference numeral 27 denotes a shaft, 28 brackets, and 29 a sensor magnet, which forms a commutation sensor on the sensor substrate 30.

4 shows a driving circuit of the driving motor. (24) is the stator winding, (25) is the permanent magnet constituting the rotor, and (P ₁ ), (P ₂ ), (P ₃ ) is the so-called commutation to detect the magnetic pole position of the rotor Sensor. The power transistors T ₁ , T ₂ , T ₃ , T ₄ , T ₅ , and T ₆ are connected in a three-phase bridge, and a stator winding is connected to the output thereof. Flywheel diodes (D ₁ ), (D ₂ ), (D ₃ ), (D ₄ ), (D ₅ ), and (D ₆ ) are connected to each transistor in parallel. The signals of the commutation sensors P ₁ , P ₂ , and P ₃ are input to the distribution circuit 31 and are configured to drive the power transistor via the amplification circuit 32.

5 shows the detailed operation of the distribution circuit 31 in time difference art. In the sections (1)-(6), when the electrostatic torque is generated, the sections (1 ')-(6') indicate the cases where the reverse torque is generated, respectively. (T ₁ )-(T ₆ ) are power transistors, and the hatched portion indicates an on state. (e _R ), (e _S ), and (e _T ) indicate the voltages applied to the R phase, S phase, and T phase of the stator winding, respectively, and the hatched portion is the positive or negative voltage. The authorization status is displayed. Each section represents the position of the rotor relative to the stator, and section 1 and section 1 'are the same rotor position. Intervals 2 and 2 ', intervals 3 and 3'. There is also a stop. Now, comparing the sections 1 and 1 ', the transistors T ₁ and T ₆ are turned on in the section ₁ , and each applied voltage is positive (e _R ), (e e) _S ) is negative and generates an electrostatic torque. On the other hand, in the section 1 ', since the transistors T ₃ and T ₄ are on, (e _R ) is negative, (e _S ) is positive, and the reverse voltage is applied to the section 1. Reverse torque occurs. This is the same as in a general direct current motor, in which a power supply terminal is connected in reverse to reverse braking.

In FIG. 5, for the sake of simplicity, the transistors are all energized in each section. However, as described later, RWM is controlled by signals of speed and position, and an average voltage applied to the stator winding is shown. With this change, the rotational torque in the forward or reverse direction is controlled.

6 shows a block diagram of the whole embodiment of the present invention. Reference numeral 33 denotes a sewing machine pedal, which corresponds to (6) in FIG. 1, and is connected to the speed commander 34 and the position commander 35 and according to the displacement amount of the pedal, the speed command signal e ₁ and the position command. Generate signal e ₂ , respectively. Reference numeral 36 denotes a comparison circuit, which compares the speed command signal e ₁ and the speed detection signal e _{3 with the} position command signal e ₂ and the position detection signal e ₄ , respectively. Print (e ₅ ). Reference numeral 37 denotes an amplifier, which amplifies the difference signal e ₅ . Reference numeral 38 denotes a PWM circuit, which changes the duty frequency in accordance with the period of the oscillator 39 and the difference signal e ₅ . Numeral 40 denotes a determination circuit for determining the government of the difference signal e ₅ . Reference numeral 41 denotes a distribution circuit, which receives the output of the commutation sensor 42 and the determination circuit 40 and gives the output to the drive circuit 43 as shown in FIG. The drive circuit 43 is as shown in FIG. The electric motor 44 and the commutation sensor 42 are as described in detail in FIG. The speed detector 45 generates a pulse of a frequency proportional to the speed of the sewing machine, and is converted into an analog-like speed detection signal e ₃ by a subsequent F / V converter 46. Reference numeral 47 denotes a position detector, which outputs two signals as an encoder method using light. One signal is configured to output one pulse per revolution, and the other outputs, for example, 360 pulses per revolution. Reference numeral 48 calculates two signals of the position detector 47 as an operation circuit and outputs an analog signal.

Next, the operation of FIG. 6 will be described using the time difference art of FIG. (e ₁ )-(e ₅ ) are the signals in FIG. 6, (P ₁ ) is one pulse signal in one rotation of the position detector 47, and (P ₂ ) is 360 pulse signals in one rotation. Display. (I _M ) is the average value of the motor current, (+) denotes the current at blackout, and (−) denotes the current at reverse braking. (V) indicates the rotational speed of the sewing machine.

Now, when the pedal 33 is pressed to the intermediate speed position at (t ₁ ), the motor current I _M proportional to the difference signal e ₅ between the speed command signal e ₁ and the speed detection signal e ₃ is obtained. Since (e ₅ ) is positive, a voltage is applied by the judging circuit 40 to generate an electrostatic torque, and is operated at an intermediate speed. At (t ₂ ), when the pedal is pressed further to the high speed position (e ₁ ), the sewing machine is driven on the highway.

The sewing machine is shifted in accordance with the amount of stepping on the pedal 33 as described above. Next, when the pedal is returned to the neutral position at (t ₃ ), the memory circuit of the speed commander 34 is set so that a predetermined low speed e ₁ is output. according to (e ₅₎ (I _M), but the count is to be controlled (e ₅₎ a voltage is applied to the braking torque by the determination circuit 40 occurs because the signal of the sewing machine speed is indicated by (V) As shown in Fig. ₃ , the speed decreases sharply at (t ₃ ) and the low speed operation is performed at (t ₄ ). In the state of the neutral position of the pedal 33 and the sewing machine speed V reached at a predetermined low speed, that is, by the memory circuit of the position commander 35 at (t ₄ ), the position command signal e ₂ Is set. Next, to generate a low-speed signal (e ₁₎ and is reset, and (p _1), the calculation circuit 48, a position detection signal (e ₄₎ is set by the detection signal by the position (p _1). (e ₄ ) is a signal that decreases in a step shape each time the position detection signal p ₂ is counted. In this example, if 4 pulses are counted, (e ₄ ) becomes 0, and the sewing machine is predetermined. Position, that is, at the position of the 4-pulse scale of (p ₂ ) from the (p ₁ ) pulse switch. In addition, in the above embodiment the position detection signal (p ₂₎ of a given when counting the number of pulses has been described for the case where the braking current to zero, detecting this position signals (p ₁₎ starting the braking, and the speed detection signal by The braking current may be zero because (e ₃ ) becomes zero.

As apparent from the above description, the present invention provides a clutch-free motor by transmitting a rotational force and a braking force of the electric motor directly to the sewing machine without interposing the clutch and the brake by using the brushless electric motor capable of variable speed driving and reverse braking operation. It eliminates the sliding friction part of a brake and enables the remarkable long life. In addition, compactness and weight reduction are realized by abolition of the clutch brake and flywheel, and the weight is reduced by about 40% compared with the clutch type. The direct drive type also stops the motor when the sewing machine stops, so the power consumption is about 60% in the standard operation method of 2 seconds on and 2 seconds off. In addition, since brushless motors use permanent magnets, the time constant can be reduced compared to electromagnetic clutches, and high speed stability and high responsiveness can be realized to increase the precision of the stop position of the sewing machine needle. .

As described above, the present invention can provide an extremely good sewing machine driving apparatus having various effects.

Claims (3)

A brushless motor, a speed detector connected to the output of the motor, a sewing machine needle position detector, a speed control mechanism of the electric motor, a sewing machine needle position control mechanism, and a speed command signal of the pedal of the sewing machine and the speed detector A sewing machine having a means for controlling the speed of the electric motor as a comparison of the speed signal of the motor, and having a means for stopping the electric motor by stopping and reversing the electric motor by a stop command signal of the pedal and a needle position signal of the sewing machine needle position detector; Drive system. 2. The sewing machine driving apparatus according to claim 1, wherein the reverse braking is started by the first needle position signal, and the reverse braking is completed by counting a predetermined number of pulses of the second needle position signal. 2. The sewing machine driving apparatus according to claim 1, wherein the reverse braking is provided by the needle position signal, and the reverse braking is terminated by detecting the stop state of the speed signal.

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