JPH0644959B2 - Sewing machine speed controller - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sewing machine that performs sewing with a rotational force obtained via a pulley, a motor that serves as a drive source for the sewing machine, and a speed control circuit that controls the motor. The present invention relates to a sewing machine speed control device equipped with.

2. Description of the Related Art A conventional sewing machine speed control device will be described below with reference to FIG.

In FIG. 5, 1 is a sewing machine, 2 is a sewing machine stand, 3 is a pedal, 4 is a motor for driving the sewing machine 1, 5 is a needle position detector, 6 is a braking device, and the sewing machine 1 is a sewing machine pulley 7 and a motor pulley. Rotational force is obtained from the motor 2 by connecting 8 with a belt.

Regarding the sewing machine speed control device configured as described above,
The operation will be described below.

The pedal 3 can be depressed forward and backward, and a signal corresponding to the amount of depression is set in the control device 6 as a sewing machine target speed signal. On the other hand, the control device 6 measures the actual speed of the sewing machine by the built-in speed detector, compares it with the sewing machine target speed signal, and controls the motor so as to minimize the deviation. When the sewing machine speeds are actually measured and compared as described above, the diameter ratio of the sewing machine pulley 7 to the motor pulley 8 (hereinafter, referred to as pulley ratio) is kept constant.
In other words, accurate speed control cannot be achieved unless the proper motor pulley 8 is selected so that the number of revolutions per revolution of the sewing machine becomes a predetermined value. Therefore, a sewing machine speed control device that solves the above problem is proposed by measuring the motor speed and comparing the result with a signal obtained by converting the sewing machine target speed signal into a motor speed (hereinafter referred to as a motor target speed signal). Has been done. The content is that by adding a speed detector that outputs R signals per motor rotation to the motor side, it becomes possible to measure the actual speed of the motor (hereinafter referred to as the motor actual measurement degree). By including a counter that counts the output signal of the speed detector generated between the output signals of the needle position detector 5 and a multiplier that can set a multiplication value, the multiplier can be used until the counter finishes counting. A'is set as a multiplication value, and the temporary target motor speed signal is output by multiplying the target speed signal by the sewing machine. When the counter finishes counting and the result C'is output, C '/ R is calculated. It is possible to calculate the pulley ratio, that is, the number of rotations of the motor for one rotation of the sewing machine, and multiply the value by the value of the sewing machine target speed signal to output an accurate motor target speed signal. There, as a result, the pulley ratio becomes possible precise speed control also would be any value.

Problems to be Solved by the Invention However, in the above configuration, when a value larger than the pulley ratio is measured as the value of the multiplication value A ′ of the multiplier, the low speed at the time of positioning the needle becomes faster and the stop accuracy becomes higher. There is a risk that the sewing machine will be broken or the speed at the time of thread breakage will be too fast, so the minimum value among the possible actual pulley ratios,
For example, it was necessary to select a value such as 1/3 to 1/4. Therefore, when the pulley ratio is large, such as in a large sewing machine, the sewing machine speed when the power is turned on is low, and therefore it takes time to calculate the pulley ratio, and as shown in FIG. 4, the sewing machine speed after the pulley ratio calculation is rapidly increased. There is a problem such as.

The present invention solves such a problem at the time of turning on the power source, and speeds up the sewing machine by increasing the multiplication value of the multiplier stepwise from the time when the power source is turned on until the pulley ratio is calculated. Shorten the time required to calculate the pulley ratio, and
It is intended to provide a speed control device capable of obtaining smooth acceleration.

Means for Solving Problems The sewing machine speed control device of the present invention generates between the output signal of the needle position detector and the adder that outputs the result in synchronization with the output signal of the speed detector. A counter that counts the output signal of the speed detector, a multiplication value is set from one of the result of the adder and the result of the counter, and the motor is multiplied by the sewing machine target speed signal that is the output of the speed setter. It is composed of an arithmetic unit for outputting a target speed signal and an arithmetic means for determining the multiplier.

With the above configuration, the sewing machine speed control device of the present invention can increase the multiplication value by which the sewing machine target speed signal is multiplied every n rotations of the motor from the time the power is turned on until the pulley ratio is calculated. The required time can be shortened, and smooth acceleration can be obtained.

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

FIG. 1 is a block diagram of a sewing machine speed control device according to an embodiment of the present invention. In FIG. 1, 1 is a sewing machine, 3 is a pedal, and 4 is a motor for driving the sewing machine 1. Reference numeral 5 denotes a needle position detector that detects the needle position of the sewing machine 1, and includes a needle upper position signal Nu and a needle lower position signal Nd.
Is output. A speed setter 9 outputs a signal corresponding to the amount of depression of the pedal 3 as a sewing machine target speed signal. 1
Reference numeral 0 is a speed detector that outputs R signals each time the motor 4 makes one revolution, and reference numeral 11 is a frequency divider that divides the output signal n of the speed detector 10 by n. Reference numerals 12 and 13 are latch circuits composed of flip-flops. Reference numeral 14 is an adder that performs addition in synchronization with the signal of the frequency divider 11 and adds the addition value stored in the latch circuit 12 to the value currently held and outputs the result. Reference numeral 15 is a counter for counting the output signals of the speed detector 10, which is reset by the force signal Nd from the needle position detector 5. A calculator 16 multiplies the sewing machine target speed signal output from the speed setter 9 by a multiplication value to output the motor target speed. A switch unit 17 sets either the result of the adder 14 or the result of the counter 15 as data for determining the multiplication value of the arithmetic unit 16. 18 is a speed control unit,
The motor target speed signal output from the calculator 16 is compared with the actual motor speed, and a voltage signal is output to the motor 4.

Regarding the sewing machine speed control device configured as described above,
Hereinafter, the operation when the power is turned on will be described.

When the power is turned on, Ai and Ao are set as initial values in the latch circuit 12 and the adder 14, respectively. Further, the SI of the switch unit 17 is in the ON state. When the pedal 3 is depressed, the speed setting device 9 outputs a sewing machine target velocity signal corresponding to the amount of depression. S of the switch unit 17
Since 1 is in the ON state, the calculator 16 determines the multiplication value from the result of the adder 14 in synchronization with the signal of the built-in oscillation circuit, and the multiplication value is the sewing machine target speed signal output from the speed setter 9. By multiplying by, the sewing machine target speed is converted into a motor speed and output as a motor target speed signal. The speed control unit 18 compares the motor target speed signal output from the calculator 16 with the actual motor speed actually measured from the output signal of the speed detector 10, and applies a voltage to the motor 4 to minimize the deviation. Output a signal. The motor 4 is started by the voltage signal. When the motor 4 is activated, the sewing machine is activated, and the speed detector 10 also outputs a signal corresponding to the rotation angle of the motor 4. The frequency divider 11 outputs a signal to the adder 14 every time n · R output signals from the speed detector 10 are input, in other words, every time the motor 4 rotates n times. The adder 14 adds the addition value Ai stored in the latch circuit 13 to the value currently held in synchronization with the output signal from the frequency divider 11. Here, the calculator 16
Determines the multiplication value from the result of the adder 14 and repeats the above operation until the pulley ratio is calculated.

On the other hand, the needle position detector 5 outputs the needle position signal Pd every time the needle position is detected. The counter 15 indicates the needle position signal P
The output signal of the speed detector 10 is counted until it is reset at the trailing edge of d and then reset next. Latch circuit 1
3 is the trailing edge of the needle down position signal Pd, and stores the result C of the counter 15. At the time of the second input of the needle down position signal Pd, the switch unit 17 turns S1 to the OFF state and S2 to the ON state, and thereafter maintains the current state even if the needle down position signal Pd is input. The operation is shown in a professional chart in FIG. 2. By performing the above-mentioned operation, the arithmetic unit 16 performs the operation as shown below. The multiplication value 13 of the calculator 16 is determined by the equation (1).

Multiplied value: B = (Ao + Ai × j) / R (before calculation of pulley ratio, S
1 is in ON state) Multiply value: B = C / R (After calculating pulley ratio, when S2 is in ON state) J: Number of output signals of frequency divider 11: Ao: Initial value of adder 14:
A: additional value, R: number of output signals of the speed detector 10 per one rotation of the motor 4: C: result of the counter, the multiplication value obtained by the above calculation is multiplied by the sewing machine target speed signal output from the speed setter 9. As a result, the motor target speed signal is output. FIG. 3 shows the relationship between time and motor target speed. As Ao, the minimum value (1/3 to 1/4) of the possible actual pulley ratio is set. Also, depending on the needle position when the power is turned on, the sewing machine
Since there is a possibility that it will make two rotations before calculating the pulley ratio, there is a possibility that it will make two rotations before calculating the pulley ratio. Therefore, make sure that the result of the adder before calculating the pulley ratio is not greater than the actual pulley ratio. , N must be determined EFFECTS OF THE INVENTION As described above, the present invention has the result that the time required to calculate the pulley ratio can be shortened and that even a large sewing machine can be smoothly accelerated.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a flow chart showing the operation of the embodiment, FIG. 3 is a time chart showing the operation, and FIG. 4 is an operation of a conventional example. A time chart, FIG. 5 is a schematic configuration diagram of a conventional example. 5 ... Needle position detector, 9 ... Speed setting device, 10 ... Speed detector, 11 ... Frequency divider, 14 ... Adder, 15 ... Counter, 16 ... Computing device.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Isamu Isamu 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) Reference JP 61-257686 (JP, A) JP 61-257687 (JP, A) JP 61-257688 (JP, A) JP 61-257689 (JP, A) JP 61-257690 (JP, A)

Claims (1)

[Claims] 1. A sewing machine that performs sewing using a rotational force as a drive source, a needle position detector that detects a needle position of the sewing machine and generates a needle position signal, and a motor that serves as a drive source of the sewing machine.
A continuity setting device that outputs a target speed signal of the sewing machine, a speed detector that outputs R pulsed actual speed signals during one rotation of the motor, and a speed control circuit that controls the rotation speed of the motor. The speed control circuit sets an initial value when the power is turned on, and thereafter generates an addition value every n pulses of the speed signal and outputs a result A, and the speed control circuit is generated between the needle position signal. A counter that counts the actual speed signal and outputs a result C, and the target speed signal is multiplied by A / R until the counter finishes counting, and after finishing counting, C / R is the target speed. A calculator for multiplying the signal, comparing the output signal of the calculator and the speed signal,
A sewing machine speed control device for controlling the motor.