JPH01171599A - Sewing machine speed setting device - Google Patents

Abstract

PURPOSE:To set a proper speed command corresponding to the angle of rotation of a motor at the time of the start of sewing with a sewing machine by comparing the speed command and an extent of pedaling with each other and validating one of them corresponding to which the speed is lower. CONSTITUTION:A pedaling extent detector 5 outputs an electric signal corresponding to the extent of pedaling of a sewing machine pedal 4. A pulse generator 8 outputs a pulse train having a frequency proportional to the rotative speed of a motor 2 which is the driving source of the machine. A counter 9 starts counting the output pulse signal of the generator 8 at the time of the start of sewing process. A speed command converting means 10 converts the counted value of the counter 9 to the speed command of the motor 2. A speed command determining means 11 compares the output of the detector 5 with the output of the means 10 independent of the extent of pedaling of the pedal 4 and validates smaller one as the speed command. A motor control means 12 controls the motor 2 based on the speed command outputted from the means 11.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a sewing machine speed setting device that can set an appropriate speed command according to the rotation angle of a motor at the beginning of sewing with a sewing machine.

Conventional speed control of industrial sewing machines is based on variable speed control according to the amount of depression of the sewing machine pedal. That is, when the sewing machine pedal is in the neutral position, the sewing machine is stopped, and when the pedal is depressed a little, it starts rotating at a low speed, and the further the pedal is depressed, the faster the rotation speed becomes.Variable speed control is generally used. like this,
In the control of industrial sewing machines, when the sewing machine pedal is depressed from a neutral position to the deepest position, a start-up characteristic that is as quick as possible is required in order to increase sewing efficiency.

However, on the other hand, such a sewing machine that starts up quickly has a problem in that the thread tends to come off at the beginning of sewing depending on the material of the fabric to be sewn and the thread tension of the sewing machine. Therefore, when the sewing machine pedal is depressed deeply from the neutral position, the conventional sewing machine speed setting device commands the speed at a relatively low speed increase rate each time the needle position is detected, regardless of the amount of depression of the sewing machine pedal. It was equipped with a means to increase the

Problems to be Solved by the Invention However, in the conventional configuration, the speed command increases only for each needle position, so when the motor pulley is small or the motor has good responsiveness, the motor speed changes in stages. This became noticeable, and there was a problem that the continuity of the motor speed was lost.

SUMMARY OF THE INVENTION In order to solve the above problems, it is an object of the present invention to provide a sewing machine speed setting device that can set an appropriate speed according to the rotation angle of the motor.

Means for Solving the Problems In order to achieve the above object, the sewing machine driving device of the present invention has the following features:
a pedal depression amount detector that outputs an electrical signal according to the amount of depression of the sewing machine pedal; a pulse generator that outputs a pulse train with a frequency proportional to the rotational speed of the motor; a counter that counts output pulse signals of the sewing machine; a speed command conversion means that converts the counted value of the counter into a motor speed command; and a speed command that is unrelated to the output of the pedal depression amount detector and the depression amount of the sewing machine pedal. A configuration comprising a speed command determining means for comparing the outputs of the converting means and validating the lower one as a speed command, and a motor control means for controlling the motor based on the speed command output by the speed command determining means. It is.

According to the above-described configuration, the present invention detects pedal depression by a pedal depression amount detector, and counts output pulses from a pulse generator built in the motor by a counter from the time when the sewing machine starts sewing. Based on the counted value, the speed command conversion means converts it into a speed command, and the speed command determination means compares this speed command with the amount of pedal depression and makes the lower one valid as the speed. It is possible to set a speed command that increases naturally in stages according to the rotation angle of the motor, regardless of the amount of pedal depression.

Embodiment FIG. 1 is a block diagram showing an embodiment of the present invention, in which 1 is a sewing machine and 2 is a motor, which are connected to the sewing machine 1 via a motor pulley 6 and a heald 3. A pedal depression amount detector 5 inputs an electrical signal corresponding to the depression amount of the pedal 4 to the control device 7.

A pulse generator 8 is built in the motor 2 and generates a pulse train having a frequency proportional to the number of revolutions of the motor 2, and its output pulses are also input to the control device Ft7.

The control device 7 includes a counter 9 that counts the output of the pulse generator 8, a speed command conversion means 10 that converts this counted value into a speed command, an output of the pedal depression amount detector 5, and an output of the speed command conversion means 10. It is comprised of a speed command determining means 11 which compares the speed commands and makes the lower one effective as the speed command Ve, and a motor control means which controls the motor based on this speed command.

FIG. 2 shows an example of a specific circuit of the main part.

The control device 7 is composed of a microcomputer 13 and peripheral circuits. Microcomputer here】3
has a CPU, ROM, RAM, and an input/output section,
This is a so-called one-chip microcomputer.

The pedal depression amount detector 5 is connected to an input section of the microcomputer 13 via an A/D converter 14. As a result, an electrical signal corresponding to the amount of depression of the pedal 4 from the pedal depression amount detector 5 is converted into a binary code and read into the microcomputer 13 as a speed command Vs. Further, a pulse train having a frequency proportional to the number of rotations of the motor 2 outputted from the pulse generator 8 is also counted by the counter 9, converted into a binary code, and read into the microcomputer 13. The speed command Ve outputted from the output section of the microcomputer 13 is converted into an analog signal via the D/'A converter 15, and then sent to the AC power supply 17 and the rectifier diode 18 connected in parallel with it. ; One capacitor and the drive circuit 20 are input to the motor control means 12 composed of (14).Then, the motor control means 12 inputs this anag port signal and the output pulse generator of the pulse generator 8 to the F/V The motor 2 is controlled so that the deviation from the analog signal (actual speed of the motor) obtained by inputting it to the converter 21 is minimized.

Next, regarding the speed command converting means 10, a method for determining the speed command Vd by performing calculation according to the following calculation formula (1) will be described as an example.

Vd=A−C+B・・・・・・・・・・・・(1) A gain constant B: Constant C: Counter count value (O≦C≦L) L: Count end value C in equation (1) is the count value of the counter 9, which is converted into a binary number and read into the microcomputer 13. Several values of the gain constant A are preset in the ROM of the microcomputer 13, and the value corresponding to the setting value of the external switch 16 is selected. Constant B is also set in advance in the microcomputer 13, and its value is equivalent to or higher than the minimum speed (about 200 rpm). By the above calculation, various speed settings as shown in a or b in FIG. 3 can be selected regardless of the amount of depression of the sewing machine pedal 4.

Next, the operation of the sewing machine speed setting device constructed as described above will be explained using the flowchart shown in FIG.

When the sewing machine pedal 4 is depressed from the neutral position, the speed is set according to the procedure of the speed setting program shown in the flowchart of FIG. 4 stored in the ROM i'l: in the microcomputer 13.

First, in step 22, the speed command Vs is set as the speed command Ve.
is set, and motor 2 starts rotating.

In step 23, it is determined whether or not it is the start of sewing, and if it is not the beginning of sewing, step 22 is repeated, so that the motor 2 is
control. If sewing is to begin, the counter 9 is initialized in step 24 and counting of output pulses from the pulse generator 8 is started.

Next, in step 25, it is determined whether the count value C of the counter 9 has reached the count end value, and if it has reached the count value, steps 22 and 23 are repeated until the series of sewing is completed and a new sewing starts, thereby pressing the sewing machine pedal. The motor 2 is controlled with a speed command Vs according to the amount of depression of step 4. On the other hand, if the count value C has not reached the count end value, the speed command Vd is determined by calculation in step 26, and the speed command Vd is determined in step 27.
S.

Vd are compared and the lower one is set as the speed command Ve. Thereafter, this process is repeated until the count value C reaches the count end value.

According to the configuration of the above embodiment, when the sewing machine starts sewing, it is possible to set a speed command that increases stepwise in accordance with the rotation angle of the motor, regardless of the amount of depression of the sewing machine pedal.

Effects of the Invention As is clear from the examples, the present invention includes a pedal depression amount detector that outputs an electrical signal according to the amount of depression of a sewing machine pedal, and a pulse train with a frequency proportional to the rotational speed of a motor. a pulse generator, a counter that counts output pulse signals of the pulse generator from the time when a sewing process is started, a speed command converting means that converts the counted value of the counter into a speed command for the motor, and detecting the amount of pedal depression. a speed command determining means that compares the output of the machine with the output of the speed command converting means which is unrelated to the amount of depression of the sewing machine pedal, and determines whichever is lower as the valid speed command; and the speed command determining means outputs the lower one. Since the configuration includes a motor control means for controlling the motor based on a speed command,
When the sewing machine starts sewing, it is possible to set a speed command that increases gradually in a reasonable manner according to the rotation angle of the motor, regardless of the amount of depression of the sewing machine pedal. Therefore, it is an object of the present invention to provide a sewing machine speed setting device that can always provide smooth rotation regardless of the size of the motor pulley and the responsiveness of the motor, and has the excellent effect of being able to start sewing without causing thread dropout.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram showing an embodiment of the present invention, Fig. 2 is a specific circuit diagram of the main part, Fig. 3 is a diagram showing the relationship between the count value of the counter and the speed command Vd, and Fig. 4 is a flowchart showing an example of a program for speed setting. 1...Sewing machine, 2...Motor, 4...
...Pedal, 5...Pedal depression amount detector,
7...Control device, 8...Pulse generator, 9...Counter, 10...Speed command conversion means, 11...Speed Command determining means, 12.
...Motor control means. Name of agent: Patent attorney Toshio Nakao No. 1 L Figure 6--Motor 1
1st figure 2nd figure 3

Claims (1)

[Claims] A pedal depression amount detector outputs an electrical signal according to the amount of depression of the sewing machine pedal, a pulse generator outputs a pulse train with a frequency proportional to the rotational speed of the motor that drives the sewing machine, and the sewing process is started. a counter that counts the output pulse signal of the pulse generator from a point in time; a speed command conversion means that converts the counted value of the counter into a motor speed command; and an output of the pedal depression amount detector and the depression amount of the sewing machine pedal. a speed command determining means that compares outputs of the speed command converting means unrelated to the speed command and determines whichever is lower as a valid speed command; and a motor that controls the motor based on the speed command output by the speed command determining means. A sewing machine speed setting device comprising: a control means.