JPS6082080A - Controller for sewing machine - Google Patents

Abstract

PURPOSE:To improve the workability for any of high and low speed sewing machines by switching the frequency of a clock pulse from a variable frequency oscillator. CONSTITUTION:A tachometer generator 2 outputs a pulse signal train through a waveform shaper 3 in the state that a sewing machine 1 is rotated. This pulse signal train is divided in frequency in response to the set amount from a speed setter 5 from a frequency divider 4. A counter 6 counts a clock pulse from a variable frequency oscillator 7 over one period of a frequency-divided pulse PD, latched to a latch 8, the actually measured period TP is outputted to a subtractor 9, thereby controlling the drive unit 12 of the motor. Even if the frequency dividing times are equal, the speed can be varied by altering the frequency of the clock pulse of a variable frequency oscillator 7. Accordingly, the ratio of the set speeds of the stages for the depression of a pedal can be varied to obtain the prescribed reduction gear shifting curve.

Description

[Detailed Description of the Invention] Industrial Field of Application The present invention has a so-called variable speed function that drives the pedal at a predetermined speed according to the amount of pedal depression.
〇 Conventional configuration and problems related to thin control device As a conventional control device of this type for a long period of time, the signal of the speed generator is extracted as an AC voltage signal with an amplitude that is a function of the actual rotation speed, By comparing the signal after full-wave rectification, or the signal further smoothed by an RC circuit, with an appropriate reference voltage for the clutch or brake, the clutch/brake coil is actuated to excite or disconnect, and speed control is performed. For example, the so-called analog speed control method,
376, US Pat. No. 3,407,910, and the like.

However, in recent years, with the development of semiconductor control elements such as microcomputers, a digital separate control system has been developed, and for example, as seen in Japanese Patent Publication No. 56-63393, it is possible to improve reliability or reduce costs.
So-called digital speed control aiming at J-T has started to be carried out.

Although the digital speed control mentioned above has various advantages, it has not yet been perfected, and one particular feature is that when the control method changes the rotational speed of the sewing machine step by step according to the amount of depression of the two pedals, the sewing machine normally The conventional system that uses the minimum speed as the reference speed and divides the speed signal from the speed generator to obtain the reference speed is, for example, a case where 20 Orpm is adopted as the base speed to a maximum of 6
For high-speed sewing machines of 000 rpm or more, rotational speeds that are an integral multiple of approximately 20 Orpm according to the pedal depression (the speed difference between each stage is at least 20 Orpm) are not of much concern, but low speeds such as a maximum of 600 rpm or less Sewing machines are originally intended for delicate sewing work at low speeds, and therefore have the disadvantage that the speed changes too suddenly at each step speed of at least 20 Orpm, making it difficult to perform sewing work. Ta.

OBJECTS OF THE INVENTION The present invention eliminates the above-mentioned drawbacks and provides a high-speed sewing machine,
Alternatively, it is an object of the present invention to provide a sewing machine control device with good workability for both low-speed sewing machines.

Composition of the Invention The present invention provides a method of changing the frequency of the clock pulse from the variable frequency oscillator to increase the frequency of one cycle of the pulse signal from the speed generator divided by the frequency divider in accordance with the command from the speed setting device. By changing the count value of the clock pulses over the period even if the period is constant L, substituting the count value into a predetermined arithmetic expression, and controlling the drive control section of the motor. It is configured to obtain a constant speed, and even if the number of divisions is the same, the speed can be varied by changing the frequency of the clock pulse from the excavator, and the speed is also variable depending on the amount of pedal depression. As described above, the transition curve of the rotational speed of the motor can be varied.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the block diagram of FIG.

In the figure, numeral 1 represents a sewing machine driven by a motor (not shown), and is a part that performs sewing work. A speed generator 2 is attached to the sewing machine 1, and the speed generator 2
generates a plurality of equally spaced pulse signals at fixed angles per rotation of the machine. The waveform shaping circuit 3 is composed of simple control elements such as an OP amplifier or an IC in order to shape the pulse signal into a rectangular wave. The frequency divider 4 is an IC circuit whose frequency division ratio can be changed by a speed setting signal from the speed setting device 5. The speed setting device 5 is a part that corresponds to the depression position of the sewing machine pedal and outputs a stepped position signal as a speed setting signal, and is composed of several pairs of light emitting/light receiving elements arranged at positions. 6 is a counter, 7 is a variable resistor and a computation unit, and 10 is a tie l-, all of which are composed of IC circuits - in particular, they can be easily constructed using a one-chip microcomputer that incorporates all of these functions. . The driver 11 is composed of a transistor and a resistance element, and the clutch/brake coil 12, which constitutes the drive control section of the motor, is located in the electromagnetic clutch/brake coupling section of the motor.
It is configured such that the rotational force of the motor is transmitted to the output i1m+ via the lining portion. In addition, the output of the motor!
A pulley is attached to the end of the shaft of the sewing machine, and the sewing machine 1 is linked to the sewing machine 1 via the pulley and a belt.

The system is configured as described above, and its operation will be explained below.

While the sewing machine 1 is rotating, the speed is 4R ↓ 9 ke → ゛ machine inward rotation n return;
11. The waveform shaping circuit 3 outputs a signal with υg+winter, and the waveform shaping circuit 3 shapes the signal and outputs a pulse signal train as a rectangular wave. This pulse signal train is divided by the frequency divider 4 according to the set amount from the speed setter 5, for example, if the set amount is twice, it will be divided, and if it is four times, it will be divided, etc., and the divided pulse train PD will be divided. Output. The counter 6 counts the clock pulses from the variable frequency oscillator 7 over one cycle period of the frequency-divided pulse train Pn, and latches it with a latch 8 as the actual measurement period of the section immediately before the pulse section to be controlled,
The measured period Tp is output to the calculator 9. By substituting the measured period Tp into a predetermined arithmetic expression, the arithmetic unit 9 calculates -
By calculating the excitation time of the clutch coil or brake coil, setting the calculation result value Tac in the timer 10, and excitation of the clutch/brake coil 12 for the calculated time via the driver 11, the pulse section that is the control target range is generated. By controlling the above and repeating the above, the averaged rotational force is transmitted to the sewing machine head.
The ε-shin will operate at the speed determined by the speed setting device 5.

Here, when the frequency of the clock pulse of the variable frequency oscillator 7 is changed, the output value of the counter 6 changes even if the period of the frequency-divided pulse train PD is constant, and therefore the predetermined calculation The result of substituting into the formula also changes, making it possible to shift the favorable speed to a new stable speed.

Next, a specific example of calculation by the arithmetic unit 9 in the block diagram of FIG. 1 will be described with reference to FIG. In this example, the calculation curve is represented by the simplest straight line, but all other calculation possible curves may be used.

The straight line equation is expressed by the following equation.

TCB == A Tp -B However, in Fig. 2, the X-axis represents the measured period of the speed generator pulse train one section before the controlled section, and the Y-axis represents the clutch current application time in the controlled section. (in the case of positive) or the application time of the brake current (in the case of negative), and the constants A and B are fixed in the curve.

For example, when the clock pulse from the variable frequency oscillation booklet has a predetermined period, an arithmetic expression as shown in the same figure is adopted, and as shown by the point α, the period is '' out of Tp+.
['The clutch coil is excited with a duty cycle in which the clutch is engaged for the time i1, and operates to absorb the sewing machine load and maintain a constant speed.

From such constant speed operation under a normal load, for example, when the load becomes heavy, the actual measurement period becomes longer as the sewing machine rotation speed decreases, and therefore the clutch current application rate increases. Constant speed operation is performed when these are balanced.

On the other hand, when the load becomes lighter, the clutch current application rate decreases to try to lower the rotational speed, and when these are balanced, constant speed operation is performed. Furthermore, if the rotational speed extremely exceeds the set value due to some kind of disturbance or transient speed overshoot, the calculation result will be negative and the speed will be reduced quickly by applying brake current. is being measured.

Here, the coefficient in the above equation determines the gain of the system, and is arbitrarily determined in consideration of the responsiveness, stability, etc. of the system. The constant B is required to maintain the set speed under normal sewing machine load conditions and is determined by the input rate of the current.

Next, when the frequency of the clock pulse changes, for example, its period becomes smaller, the counter 6
The count value increases, and as shown in the figure, the counter value changes to TP2, and the calculation result of the clutch engagement time shifts to TCB2 (point F), and Y! Since I11 indicates real time, the duty cycle of clutch engagement increases temporarily, accelerates rapidly, and stabilizes at a speed higher than the conventional stable speed, and conversely, the period of the clock pulse becomes large. Then, 3 by the counter 6
The -1 value is small, and the clutch engagement duty cycle is reduced and decelerated, resulting in a temporary shift to 4 points, resulting in a stable speed lower than the conventional stable speed.

On the other hand, as described above, the system operates so that the period of the frequency-divided pulse signal Pn from the frequency divider 4 is always constant. In such a case, the actually measured cycle will be doubled, but the cycle will remain constant as described above, and the final machine rotation speed will therefore be stabilized by about twice. In this way, the speed setting is switched in stages, and if the dividing ratio is λ for the set speed, then the value is n times the standard set speed when it is 1. Possible. (However, n=1.2...) Here, as mentioned above, since the period of the frequency-divided pulse signal Pn is expressed by the count value of the clock pulse, the adjustment of the variable frequency oscillator 7 The count value can be continuously varied, and therefore, by adjusting the variable frequency oscillator element, it is possible to vary the set speed according to the depression stroke of the pedal by a predetermined number of frequency divisions.

Next, referring to FIG. 3, the relationship between the depression stroke and the rotational speed of the sewing machine based on the application of the present invention will be described.

In the figure, the numbers within 0 indicate the division ratio, and if the division ratio is expressed as % and the reference rotational speed is N+(rpm), then the rotational speed of the sewing machine is calculated as N 1X n Crpm). Ru.

Curve I (solid line), curve I (broken line) - curve I shown in the same figure
11. ' (two-dot chain line) corresponds to the case where the frequency of the clock pulse is normal, low, and high, respectively. Therefore, by adjusting the variable frequency oscillator, the set speed for the pedal depression stroke is continuously adjusted. It is clear that it can be selected arbitrarily.

An embodiment of the present invention has been described in more detail than the effects of the invention, but as is clear from this, the present invention uses a frequency divider to convert the pulse signal indicating the actual speed from the speed generator according to the amount of pedal depression. By dividing the frequency by a frequency division ratio determined based on the speed setting signal from the speed setting device, stepwise speed switching is performed, and the pedal depression is performed according to the setting of the frequency of the clock pulse output from the variable frequency oscillator. According to the present invention, a predetermined speed change curve is obtained by changing the ratio of the set speed of each stage to By adjusting the variable frequency oscillator, the speed difference between each stage can be continuously changed, and a sewing machine control device that facilitates sewing work and has good workability can be realized.

[Brief explanation of the drawing]

FIG. 1 is a block diagram as an example of application of the present invention, FIG. 2 is a diagram showing a calculation curve, and FIG. 3 is a diagram showing the relationship between the pedal depression stroke and the rotational speed of the sewing machine. 1...ε sin, 2...speed generator, 4
...Frequency divider, 5...Speed setter, 6.
... Counter, 7 ... Variable frequency oscillator, 9 ... Arithmetic unit, 12 ... Clutch.
Brake coil (drive control section) 8 Fig. 1 5 Fig. 3 Stroop

Claims (1)

[Claims] a motor that drives a sewing machine; a speed generator that generates a plurality of pulse signals each time the sewing machine rotates; a speed setter that generates a speed setting signal according to the amount of movement of a pedal; A frequency divider for dividing the frequency of the pulse signal from the oscillator, a counter for counting the clock pulses from the oscillator over one cycle period of the pulse signal after the frequency division, an arithmetic unit, and a drive control section for the motor. , by changing the frequency division ratio of the frequency divider according to the speed setting signal, a reference pulse according to the frequency division ratio is obtained as an output of the frequency divider, and further, the arithmetic unit is configured to obtain a reference pulse according to the frequency division ratio by changing the frequency division ratio of the frequency divider according to the speed setting signal; By substituting the count value for one cycle of the reference pulse into a predetermined calculation formula and controlling the drive control unit so that the cycle of the reference pulse is constant, the motor is controlled by the pedal. According to the T-band, the oscillator is configured with a variable frequency oscillator, and the frequency of the clock pulse is made variable, making it possible to create a kinetic kettle. ε-thin control device.