JPS6070992A - Drive device for sewing machine - Google Patents

Abstract

PURPOSE:To shorten a brake time and to improve the needle constant position stopping accuracy by employing both a reverse phase brake of a drive motor and a frictional electromagnetic brake. CONSTITUTION:When the depression amount of a pedal is returned, the output Keo of an amplifier 55 becomes negative. Thus, a discriminator 57 switches a distributor 58, a drive circuit 59 generates a reverse phase torque in a motor 61, and the motor 61 and a sewing machine are decelerated. When they becomes the speeds corresponding to the depression amount of the pedal, the motor 61 is again switched to the rotary torque of normal direction, and shifted to a safety operation. When the pedal 51 is returned to the neutral, a discriminator 54 outputs a low speed set signal e1', and the motor is shifted to the low speed. Then, a needle position signal 66 is inputted, a low speed set signal e1' is set, a brake 63 is driven by a drive circuit 60, and the motor 61 is stopped at the needle constant position of the machine.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a sewing machine drive device, and more particularly to a sewing machine drive device that performs variable speed operation including stopping the sewing machine and stopping the sewing machine needle at a fixed position.

Conventional Structure and Problems An industrial sewing machine and its driving device generally have the structure shown in FIG. In Fig. 1, 1Fi sewing machine head, 2 a detector for detecting the speed and needle position of the sewing machine,
3 is a drive motor; 4 is a control unit that receives signals from the inspection 3/purge hanger 2 and the pedal to control the drive motor 3 and the solenoid of the sewing machine; 5 is a sewing machine table; and 6 is a sewing machine pedal. are shown respectively.

The conventional structure of this drive motor 3 is as shown in FIG. This electric motor has a structure in which an induction motor and a clutch/brake mechanism are integrated. induction motor,
The drive shaft 7, the flywheel 8 coupled thereto, and the clutch friction disk 9 rotate continuously, and rotational energy is stored in the flywheel 8. The movable clutch disc 1o and the movable brake disc 11 can slide in the axial direction on splines 13 press-fitted into the output shaft 12, and each has a lining 14, 15 bonded thereto. When the clutch electromagnet 16 is now excited, a magnetic flux 17 is generated, and the clutch movable disk 10 moves to the left.

The lining 14 is pressed against the continuously rotating friction disk 9, and 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 JP-A-Sho GO-70992 (
2) The stopper 11 moves to the right, the lining 16 comes into pressure contact with the brake friction disk 2o fixed to the bracket, and the output shaft 12 stops rapidly. The rotational force of the output shaft 120 is normally transmitted to the sewing machine head 1 via a belt. Speed control of the sewing machine is performed by feeding back the speed signal detected by the detector 2 and creating a half-clutch state by adjusting the excitation current of the clutch electromagnet 16. With the development of functionality and automatic sewing machines, there is a strong tendency for this drive motor to be used for long periods of time at intermediate speeds, rather than just stopping the drive as in the past. In the electric motor of the conventional structure shown in FIG. 2, at intermediate speeds, the lining 14 is slipped and used in a half-clutch state as described above, which accelerates wear of the lining and reduces the service life. cannot be said to be sufficient. This lining is generally composed of cork as its main component, but methods such as impregnating it with special oil or applying grease whose main component is molybdenum disulfide have been put into practical use. At the same time, we tried to improve the heat dissipation of the friction surface to the limit of 1.

Although considerable longevity has been achieved, there are still limitations such as the need for regular grease application or lining replacement.

In order to improve this problem of lifespan, a method has been proposed in which the friction type electromagnetic clutch is replaced with an eddy current clutch, and has been put into practical use in some cases. This method transmits the rotational force of the flywheel to the output shaft in a non-contact manner, so as mentioned above, the latch life is clearly improved, but on the other hand, it has the disadvantage of not being able to obtain the transmission torque equivalent to the amount of light. It has some disadvantages. What performance is required for a drive motor for an industrial sewing machine?

Firstly, the acceleration/deceleration is fast (acceleration/deceleration time to 4ooofl is approximately 100m5), and secondly, when sewing original items such as jeans, instantaneous large torque (approximately 1'okg・m) is required. However, the performance of the eddy current clutch method has been limited due to thermal deformation of the eddy current generating disk (or cup).

Furthermore, these conventional methods, both the friction electromagnetic clutch method and the eddy current clutch method, have the disadvantage that they consume unnecessary power because the drive motor is constantly kept rotating regardless of whether the sewing machine is started or stopped. has. Normally, the operating time of a sewing machine is 20 to 30 inches, and the remaining 70 to 8 hours.
0% means that the motor is running idle, and during that time, a 1φ400W motor wastes about 100W, and a 3φ400W motor wastes about 50W.

OBJECTS OF THE INVENTION The present invention eliminates the above-mentioned conventional drawbacks, endures long-term operation at intermediate speeds, achieves energy savings, and
The purpose is to obtain good stopping characteristics.

Composition of the Invention The sewing machine drive device of the present invention has a permanent magnet in the rotor,
A so-called brushless morph that switches the energization phase of the stator winding depending on the rotor position.

It consists of an electric motor coupled with a low-inertia friction-type electromagnetic brake and a braking mechanism for these. It is a first braking means for anti-phase braking of the electric motor, and a braking device that drives the braking device described on the previous page 7. It is an object of the present invention to provide a new sewing machine driving device which has a second braking means for controlling the sewing machine and which eliminates all the drawbacks of the conventional sewing machine.

Description of examples An embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 is a structural sectional view of the drive motor. In Figure 3, 21 is a rail base attached to the sewing machine table;
2 is a frame, and 23 is a stator core, which has, for example, 24 slots. A stator winding 24 is embedded in the slot and connected thereto. A permanent magnet 26 is bonded to the rice pad 26 and magnetized into four poles in one circumferential direction.

Note that the outer periphery of the permanent magnet 26 is taped for reinforcement. 27 (d-axis, 28 is a bracket, 29 is a ball sensor magnet for detecting the position of the rotor, and is magnetized in the same manner as the magnet 26. 3o is a printed circuit board, and 29 is a ball sensor magnet for detecting the position of the rotor. Three magnetic sensors are arranged in the circumferential direction at positions facing 29. 31 is a brake friction disk made of a magnetic material. 32 is a brake boss made of a non-magnetic material such as aluminum, and a lining 33 is provided on the end surface.
is glued and at the same time fixed to the shaft with a key 34. 36 is a brake electromagnet, 36 is a screw, and a bottle 38
037, which is fixed to the bracket 28, is a sleeve holder, which is fixed to the brake friction disk 31 by a method such as press-fitting. 39 is a coil spring which lightly presses the friction disk 31 against the lining. 4o is a cover, 41 is a pulley, 42 is a pulley cover, and 43 is a cooling fan.

By switching the energization phase of the stator winding 29'i and the rotor magnet 2 using the method described later and performing PWM (pulse width modulation) control, a torque of any magnitude in any direction can be applied to the rotor magnet 2.
6 can occur.

The brake friction disk 31 is movable in the axial direction by sliding between the pin 38 and the cylindrical bearing 37 and is supported in a fixed manner in the rotational direction, so when the brake electromagnet 35 is energized, it is pressed against the lining 33 and the brake boss 32 via which the shaft 27 comes to a rapid stop.

Figure 4 shows the drive circuit of the drive motor.]
! It is. The stator winding 24 in FIG.
The connection is made as shown in . Power transistor T1T2. T4, T5, and T6 are connected in a three-phase bridge configuration, and the connection point of %Ti+72, T3. The connection point of T6 and the connection point of T5+T2 are the above-mentioned R and S, respectively.
, % each transistor has a flywheel diode D1 . connected to the T-phase winding. D2. D3゜D4 r D5
t D6 is connected. A signal from the magnetic sensor Pi + p21 p3 for detecting the position of the rotor magnet 26 is input to a distribution circuit 68 and is configured to drive the power transistor via an amplification circuit 67.

FIG. 5 shows details of the distribution circuit 68 in the form of a time chart. Sections 1 to 6 indicate the case in which forward rotation torque is generated, and sections 1' to 6' indicate the case in which reverse rotation torque is generated. T1 to T6 are power transistors, and the shaded portions indicate the on state. 'R+68+θ' indicates the voltages applied to the R phase, S phase, and T phase of the stator winding, respectively, and the shaded area indicates the application state of positive or negative voltage.

10B eRB + eST r 6TR indicates the line-to-line applied voltage, and the shaded area indicates the application state of positive or negative voltage.

1. Looking at the first section, power transistors T1 and T6
is on, and a current flows from the power supply through the R and S phases to return to the -E constant power supply, and the voltages of each phase are as shown in Figure 6, and from the relationship with the rotor magnet 26, the current is Generates rotational torque. When entering the next second section, transistor T1
continues to be on, T6 is turned off and T2 is turned on, so that current flows from the R phase to the T phase, and the rotational torque in the forward direction continues.

When the distribution circuit 68 is switched by a signal from a determination circuit to be described later, it is switched to sections 1' to 6', and the 6th
A voltage is applied to the stator winding in the state shown in the figure, and rotational torque in the opposite direction is generated.

FIG. 6 shows a block diagram of the entire embodiment. 61 is a sewing machine pedal, which corresponds to 6 in FIG.

A pedal position detector 62 converts the amount of displacement of the pedal into an electrical signal and outputs a speed setting signal e1.

The 11 vane comparison circuit 63 receives the e1 and the sewing machine speed signal e, which will be described later.
2 and outputs a signal 9o=e1-e2.

The determination circuit 64 is a circuit that outputs a low speed setting signal 01' when the pedal is changed from a depressed state to a neutral state, and also outputs an AND output of the condition that the pedal position is neutral and the condition that there is a needle position signal. The amplification circuit 65 receives the output 6Q of the comparison circuit.
The signal is amplified and an output called keo is output. PWM circuit 66
is a switching regulator, which receives the input of the keo.

Outputs a variable duty output at a constant frequency (around 2kHz). The determination circuit 57 uses the output ke of the amplification circuit 66.
(This is a circuit that determines whether 1 is positive or negative. The distribution circuit 68 is a logic circuit that receives the output of the pole sensor described later and the output of the determination circuit 57 described above, and provides an output as shown in FIG. 6 to the drive circuit 59. The drive circuit 59 is as shown in FIG.

This is a circuit that drives a brake 63, which will be described later. electric motor 61
．． Pole sensor 62. The brakes 63 are all as described in detail in FIG. Speed detection JP-A SHO GO-709
92(4) The device 64 generates a pulse with a frequency proportional to the sewing machine speed, and the subsequent F/V converter 66 converts the analog signal e2 into
is converted to The needle position detector 66 obtains a signal of the needle position by optical or magnetic method, and the above-mentioned determination circuit 64
is input.

Next, the operation shown in FIG. 6 will be explained. When the pedal is in the neutral state, it is el-o, and since the sewing machine is not operated, it is 02-0, so eo=ke, )-0. Therefore, the electric motor 61 does not operate. When the pedal 51 is depressed, el becomes a positive voltage, the electric motor 61 starts rotating, the sewing machine is driven via the belt, and the sewing machine speed increases to t.
In comparison with f6z, the PWM 56 applies a duty pulse waveform along this feedback loop to the subsequent drive circuit 59, so that the electric motor 61 generates the necessary torque, and the sewing machine adjusts the amount of depression of the pedal 51. Rotate at the appropriate speed.

When the amount of pedal depression is returned, the output keo of the amplifying circuit 66
becomes negative, the determination circuit 67 switches the distribution circuit 58 to 13'', which corresponds to the section 1' to 6' in FIG. The electric motor 61 and the sewing machine are decelerated,
When the speed corresponds to the amount of pedal depression, the electric motor 6 is turned on again.
1, the rotational torque is switched to the positive direction and the operation shifts to stable operation.

When the pedal 61 is returned to the neutral position, the determination circuit 54 outputs the low speed setting signal e,/, which is compared with the speed signal e2 in the comparison circuit 53, and the motor shifts to low speed as described above. Thereafter, by inputting the needle position signal 66, the low speed setting signal e, / is reset and a signal is output to the drive circuit 60, which in turn outputs the signal to the brake 63.
, and the electric motor 61 stops at the needle position of the sewing machine.

FIG. 7 shows the above-mentioned operation in a time chart. PD indicates the state in which the pedal is depressed, and M (FW) indicates the state in which the motor stator winding is energized in the positive direction.

M(BY) indicates the reverse energization state to the motor stator winding, BR indicates the energization state to the brake, ND indicates the output signal of the needle down state of the sewing machine, and SP indicates the sewing machine speed.

In sewing machine speed sp, 81 is high speed page 14 S2 indicates a low speed state.

When the pedal is depressed 1 at time t1, a pulse voltage in the forward rotation direction is applied to the electric motor, the sewing machine speed SP is accelerated, and when the sewing machine speed SP approaches the set speed S1, the aforementioned PWM circuit reduces the duty of the output pulse. Then, at time t2,
Shift to stable speed. Although not shown, by adjusting the amount of depression of the pedal PD, the duty of the pulse voltage applied to the motor changes, and the sewing machine speed SP can be freely adjusted accordingly. At time t3, when the pedal is returned to neutral, a pulse voltage in the reverse rotation direction is applied to the motor, the motor is braked in reverse phase, and the sewing machine speed sp is decelerated, and when it reaches time t4 and reaches low speed S2. The electric motor is again switched to a pulse voltage in the forward rotation direction, and is operated at low speed S2. Thereafter, when time t5 arrives and the needle down signal ND is input, the brake BR is driven and the sewing machine stops at the needle down position. After a certain period of time, at time t6, the brake excitation is released and the brake is released.

FIG. 8 shows a block diagram of the second embodiment.

The only difference from the 15-page Fig. 6 is the configuration of the brake drive circuit 6°. The drive circuit 60 is configured to be driven under an AND condition of the output of the PWM circuit 56 and the output of the determination circuit 57 and an OR condition of the output of the determination circuit 64. That is, the brake 63 is driven under the same conditions as the anti-phase braking of the motor 61 during the interval t3 to t4 in FIG. 7, that is, in synchronization with M(BW). The period from t5 to t6 is driven by the output of the determination circuit 54, and is therefore the same as that shown in FIG.

Effects of the Invention As is clear from the above description, the present invention transmits the rotational force of an electric motor directly to the sewing machine without using a clutch, and connects the electric motor to a rotor having a permanent magnet and a stator winding connected in three phases. and by controlling the electric current to the stator winding using PWM.

It is capable of variable speed operation, and by configuring the permanent magnet with a material with high magnetic flux density and small external dimensions, low inertia can be achieved, which is compatible with the basic characteristics of a DC motor's large starting torque. 1. It is possible to realize extremely fast acceleration/deceleration performance and instantaneous large torque generation suitable for sewing special objects. At the same time, since there are no contact parts or sliding parts on the drive side, it is possible to achieve an extremely long life that can sufficiently withstand continuous intermediate speed operation. ! Since the drive motor is driven only when the sewing machine is operating, a sewing machine driving device with extremely low power consumption can be realized.

Further, the present invention can provide a sewing machine drive device which has an extremely short braking time and has good stopping accuracy at a fixed position by using reverse phase braking of the drive motor and a friction type electromagnetic brake.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing a configuration example of a general sewing machine and a sewing machine drive device, Fig. 2 is a sectional view showing the structure of a conventional drive motor, and Fig. 3 is a sectional view showing the structure of the drive motor section of the present invention. 4 is a circuit diagram showing the drive section of the present invention, and FIG. 6 is a time chart showing the operation of the distribution circuit 68 of the present invention.
Fig. 6 is a block diagram showing the overall operation of the present invention, Fig. 7 is a time chart for supplementary explanation of the operation in Fig. 6, and Fig. 8 on page 17 is a block diagram showing the second embodiment of the invention. It is. 24...Stator winding, 26...Permanent magnet, 29...Pole sensor magnet, 61...
... Pedal, 62 ... Pedal position detector, 6
6... PWM circuit, 69° 60... Drive circuit, 62 Old... Pole sensor, 63...
...Brake, 64...Speed detector, 66...
...Needle position detector. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 3
Figure 2729 @Figure 4, 59

Claims (4)

[Claims] (1) A sewing machine drive mechanism having an electric motor and a braking device, a sewing machine speed detector and a sewing machine needle position detector connected to the output side of the electric motor, and a speed control of the electric motor according to the pedal position of the sewing machine. The electric motor includes a permanent magnet in a rotor and a position detection element that detects the position of the rotor, and the speed control mechanism is configured to control the speed according to an output signal of the position detection element. The motor is equipped with a drive circuit that switches the phase of the stator winding of the electric motor, and the speed of the sewing machine can be controlled by comparing the pedal position and the speed detector signal, and the electric motor can be controlled based on a deceleration instruction from the pedal. and a first braking means for anti-phase braking. A sewing machine driving device having a second braking means for driving the braking device. (2) The sewing machine drive device according to claim 1, wherein the second braking means is a friction type electromagnetic brake. (3) The first braking means is configured to be effective when decelerating to a lower speed than the normal operating speed, and the second braking means is configured to be effective when stopping at a fixed position based on the signal from the needle position detector from a low speed. A sewing machine driving device according to claim 1. (4) The sewing machine driving device according to claim 1, wherein the first braking means and the second braking means are configured to be driven in synchronization.