JPS6366555B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention provides variable speed control of a sewing machine according to the separation distance from a specified position of a pedal, and also controls the sewing machine at a specified speed as the pedal moves to a specified position. The present invention relates to a sewing machine driving device having a so-called needle fixed position stopping function, which positions and stops the needle at the needle position.

Conventional configuration and problems thereof Conventionally, as a method for stopping the hands at a fixed position, a method as shown in the time chart of FIG. 1 has been generally adopted.

Normally, a sewing machine uses a motor through a belt to
Alternatively, the sewing machine is directly driven, and by operating the pedal of the sewing machine, the sewing worker controls the motor through the control unit, and further controls the sewing machine's variable speed or stops the needle at a fixed position while sewing a predetermined sewing product. A series of tasks will be carried out to complete the project.

Generally, when the sewing machine leaves the pedal in an open state (hereinafter referred to as neutral) where no force is applied by the sewing worker, the sewing machine remains in a stopped state, and when the pedal is depressed for a predetermined distance or more, The sewing machine is driven, and the speed varies depending on the treading distance.
Variable speed control is provided up to the maximum speed.

In FIG. 1, when the pedal is depressed to its maximum position, the sewing machine is operating at maximum speed. When the sewing worker returns the pedal to the neutral position from such a state, the pedal position is first detected, the signal "PN" is switched from "L" to "H", and the signal "PN" is switched from "L" to "H". As a result, the sewing machine is set to a low speed "NL" (hereinafter referred to as position speed) for positioning, and is rapidly decelerated. Next, after reaching the position speed "NL", the sewing machine is positioned and stopped when the needle position signal "ND" indicating the position to be stopped is confirmed.

The above operation is performed, but here, the time "TL" from reaching the position speed "NL" to confirming the hand position signal "ND" is the longest time equivalent to one rotation at the position speed. It takes time, and the rotation angle position when the position speed is reached varies variously within the maximum time.

The above-mentioned time "TL" is very long because the above-mentioned position speed "NL" is low, and is an important factor that significantly reduces sewing efficiency. Another disadvantage is that the time "TL" changes every time the sewing is done, and the rhythm of the sewing does not match, making it impossible to perform the sewing work smoothly.

In order to improve sewing efficiency, in the conventional method, there is no choice but to increase the position speed "NL"; on the other hand, increasing the speed causes the stop position during positioning to change due to speed fluctuations and voltage fluctuations. As a result, the needle position cannot be determined and the function of stopping the needle in the fixed position cannot be performed, which hinders the sewing work and has reached its limit. .

As mentioned above, the conventional method has the disadvantage that it takes a long time to sew between the final stitches during positioning, which reduces sewing efficiency. However, there is a limit to the accuracy of stopping the needle position, and countermeasures for these two conflicting problems are extremely difficult and have not been solved at present.

OBJECTS OF THE INVENTION It is an object of the present invention to provide a sewing machine drive device that eliminates the above-mentioned drawbacks, improves sewing efficiency, and has high accuracy in stopping the needle at a fixed position.

Composition of the Invention The present invention first enables the selection of a target stop position with a simple operation, and also provides a position measuring means that constantly measures the current rotational angle position with respect to the target stop position in the process of stopping the needle at a fixed position. and a speed detecting means for actually measuring an instantaneous speed, one of the plurality of conversion elements is set according to the measured speed, and data included in the conversion element and instructing the speed setting is set according to the measured rotation angle position. By arranging each of the conversion elements so that the speed setting value data is maximized at a passing position of the target stop position and minimized just before that, the rotation angle position The sewing machine attempts to stop the sewing machine at a target position using a predetermined braking curve based on the results while actually measuring the speed and speed, and is characterized in that the braking curve can be freely selected by selecting the speed setting value data. Therefore, the sewing time for the final stitch can be made sufficiently short and constant, making it possible to improve sewing efficiency, and furthermore, it is also possible to maintain the speed just before the target stop position or lower it. , it is possible to achieve needle position stopping accuracy with less variation than before, and the stopping position can be easily selected, and when constructing a digital speed control system, for example, one-chip microcomputer (which has been commonly used in recent years) It has many advantages, such as being able to be constructed at a very low cost by making full use of microcontrollers (hereinafter referred to as microcomputers).

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

In the figure, reference numeral 1 denotes a frequency generator, which is attached to the shaft end of the sewing machine and outputs a plurality of pulse signals "FP" with a period proportional to the rotational speed of the sewing machine per rotation. 2 is a needle position detector, which is attached to the shaft end of the sewing machine in the same way as frequency generator 1, and outputs needle position signals "ND ₁ " and "ND ₂ " corresponding to the upper and lower positions of the sewing machine needle. It happens.
3 is a speed setting device and a sewing machine pedal (not shown)
It detects the state of , outputs a signal "PN" at the neutral position, and outputs a 4-bit speed command signal "SV" at a depressed position, which changes in accordance with the pedaling distance. Reference numerals 4 and 5 denote a clutch coil and a brake coil, respectively, which are built into the output section of the motor 6, and when the clutch coil 4 is excited, the rotational force of the constantly rotating motor 6 is transmitted to the clutch lining and output through its magnetic circuit. The power is transmitted to the sewing machine through a shaft (not shown) and further via a pulley belt, and on the other hand, the excitation of the brake coil 5 presses and engages the brake lining (not shown) to the stationary side through its magnetic circuit, as described above. The action of transmitting the stationary force to the sewing machine is as follows. Normally, variable speed control is performed by controlling the excitation current to the clutch coil 4, controlling the pressure contact force on the clutch lining surface, and producing appropriate slippage.

The other parts are blocks of electronic circuits and can be replaced with discrete ICs, etc., and these will be explained one by one according to the operation explanation below.

First, when the speed setting device 3 detects the depression of the pedal and the signal "PN" changes from "H" to "L", the stop control means 7 sets the signal "CLD" to "L" for a short time.
→ "H" is set and the flip-flop (hereinafter referred to as F/F) 9 is energized via the OR gate 8 and the clutch coil 4 is energized via the set reset driver 10, and the sewing machine is started as described above.

The speed of the sewing machine that has started rotating as described above will be controlled digitally as shown below, but this method was immediately disclosed in the patent application filed in 1983-
This is disclosed in No. 139071 or Japanese Patent Application No. 139073.

The above-mentioned speed control is shown in FIGS. 3 to 5, and the same figures will also be explained below.

While the sewing machine starts rotating as described above,
The speed command signal “SV” from the speed setter 3 is 4.
The speed command signal "SV" is output as bit data, and the speed command signal "SV" is given as address data of RM11, and by selecting the contents of the corresponding RM address, it is converted into a speed setting value indicating the number of divisions for speed setting, which will be described later. After that, the data selector 12 is output. The data selector 12 outputs the input on the "B" side because the input to its select terminal "S" is "L", and therefore the speed is set based on the speed command signal "SV" from the speed setting device. The set value "DV" is output and set in the frequency divider 13.

The frequency divider 13 divides the pulse signal "FP" outputted from the frequency generator 1 by the number of times of the set speed setting value "DV", and then outputs the signal "PD". The period counter 14 counts the clock pulse signal from the clock oscillator 15 over one period of the frequency-divided signal "PD", holds the counting result by the latch circuit 16, and calculates it as 8-bit period data "TP". output to the device 17.
Note that the clock pulse signal is an oscillation signal with a sufficiently short cycle relative to the frequency-divided output signal "PD", so that the speed will not change due to measurement errors, for example, variations in the cycle of one pulse. It is necessary to select a pulse signal with sufficiently short resolution that the control system is not affected much.

After the arithmetic unit 17 performs the arithmetic operation described later,
According to the calculation result, if the periodic data “TP”
If is large (low speed), or gate 8,
The clutch coil 4 is excited through the F/F 9 and the driver 10, and if the period data "TP" is small (high speed), the OR gate 18,
It acts to excite the brake coil 5 via the F/F 19 and the driver 20, and its operating time is:
It is determined by presetting one operation result data by the arithmetic unit 17 in the preset counter 21 as 8-bit data, and counting the clock pulse signal by the number of data, and after this operation time has elapsed, the F/F 9 or The F/F 19 is reset and the clutch coil 4 or brake coil 5 is turned off.

In this way, after actually measuring the frequency-divided data "TP" of the pulse signal "FP" output from the frequency generator 1 and performing calculations, the clutch coil is 4 or brake coil 5, the actual measurement and control are repeated one after another to achieve speed control.The details are shown in FIGS. 3 to 5, and will be described below according to the same figures. .

FIG. 3 is a graphical representation of an example of the arithmetic expression by the arithmetic unit 17, where T _CB = AT _P -B (1) (where A, B: constant, T _P : measured period, T _CB ; indicates clutch or brake engagement time).

In the above equation (1), the constant A determines the rate of change in the clutch/brake engagement time T _CB with respect to the measured cycle T _P , and is therefore considered to be a constant that determines the gain of the speed control system, It is determined by considering the stability or responsiveness of the system. On the other hand, constant B determines the rotation speed of the sewing machine, and when the load on the sewing machine is determined and the frequency division number is 0.
This is uniquely determined by determining the speed at which the vehicle is moving (hereinafter referred to as the reference speed).

If the sewing machine is operating stably at point α shown in the same figure, a clutch current IC flows according to the duty cycle T _CB1 in period T _P1 as shown in Fig. 4 a, This will balance the load on the sewing machine.

FIG. 4b shows the state of acceleration, and as the sewing machine accelerates, the measured period TP becomes shorter.
Therefore, the calculation results from the above calculation formula are also T _C1 , T _C2 ,
The above operation is repeated until the clutch _current IC decreases and reaches a stable state in which it balances the sewing machine load.

On the other hand, Figure c shows the process in which the sewing machine gradually decelerates, and as the measured period "TP" increases, the brake-on time decreases to T _B1 , T _B2 , and the clutch-on time T _C1 , T _C2 , T _C3 , thus representing the process of switching from a decrease in brake current I _B to an increase in clutch current I _C.

The above has described the operation at the reference speed, but by substituting the data after dividing the frequency by the number of divisions n as the actual measurement period "TP", it is possible to change the load of the sewing machine depending on the rotational speed. If the gain of the speed control system is sufficiently high, a stepped sewing machine speed as shown in equation (2) below can be obtained.

N _S = (n + 1) N _L ...(2) (However, n: Number of divisions N _S ; Sewing machine speed N _L ; Reference speed) From the above, 4 of the speed command signal "SV" corresponding to the pedal position It is clear that by appropriately assigning the frequency division number to each address of the RM11 indicating bit data, it is possible to set the sewing machine speed for the pedal depression position, and an example of this is shown in FIG. ing. Note that the number of frequency divisions n is shown in parentheses.

As described above, variable speed control is performed when the pedal is depressed.Next, the operation when the pedal is placed in the neutral position will be described.

Here, 22 is the needle up/down position signal "ND ₁ "
23 is a position counter, and while the _sewing machine is running, the needle position signal selected by the switch 22 is sent every one rotation. While being reset at the previous edge of "ND", the pulse signal "FP" from the frequency generator 1 is counted repeatedly, and therefore its output "P" is based on the previous edge of the needle position signal "ND". This shows the rotational angle position data. For example, if a 160-pole frequency generator 1 is used, the position data "P" will have rotational angle position data from 0 to 160 as an 8-bit binary value. Furthermore, the position data “P” is RM2
4, RM25, and RM26, and a speed setting value corresponding to the frequency division number n is assigned to each RM in correspondence with each address.

An example of data allocation to each of the above RMs is shown in FIG. As shown in the figure, there are five types of data for the above-mentioned position data "P", and the data shown in parentheses is assigned to each address.
That is, RM24 is 6 to 2, RM25 is 9
~5, RM26 assigns 4 to 0 to the position data in five stages such that the position through which the front edge of the needle position signal passes is the maximum and the position immediately before that is the minimum.

As mentioned above, when the pedal is depressed and the sewing machine is operating at high speed, when the pedal is brought to the neutral position, the speed setting device 3 first detects the neutral position of the pedal and outputs the output signal "PN". L"→
This output signal "PN" switches the data selector 12 to the "A" input selection state and instructs the stop control means 7 to start needle fixed position stop control.

Here, the stop control means 7 is usually constituted by a microcomputer, and an example of its control operation is shown in a flowchart in FIG. 7, and the operation will be described below with reference to the same figure.

In the main routine, all flags are set at 27, and _C1 if the pedal is depressed.
~ _C3 output is in its initial state. Next, the pedal is set to neutral and the signal “PN” changes from “L” to “H”
Then, by inputting the interrupt of the frequency-divided pulse signal "TP", the TP interrupt processing first sets _C1 to "L" and selects the RM24, as shown at 28.
The data of the RM 24 selected as described above is sent to the frequency divider 13 via the data selector 12.
After the pulse signal "FP" is frequency-divided by the set number of divisions "DV", its period is actually measured and given as "TP" to the stop control means 7 again in the next cycle. In step 29, it is determined whether the period "TP" measured in this manner is equal to or greater than the set value _TP1 . In other words, this judgment is to judge whether the speed is higher than the speed shown by the two-dot chain line in Fig. 6. If the speed is high, then C ₂ is set to "L" at 30.
Then select RM25.

The selected RM25 has the position data "P"
While outputting the speed setting values 9 to 5 according to the following, it is repeatedly determined whether the actually measured period "TP" is greater than or equal to the setting value "TP ₁ " at step 31, and the actual measured period "TP" is equal to the setting value "TP ₁ ". When this happens, set FLN ₁ .

Thereafter, when the front edge of the needle position signal "ND" is confirmed at step 32, FLN2 is set, _C3 is set to "L", RM26 is selected, and the speed setting is successively lowered. It will be done.

As described above, after the speed setting value "O" of the RM26 in FIG. 6 is selected and the sewing machine is set to the lowest speed, the reference speed, the needle position signal " When the front edge of "ND" is detected, the "BRD" signal is output for the time required to stop, the brake coil 5 is energized, and the sewing machine is stopped at a predetermined needle position.
Completes a series of needle fixed position stop control.

The above operation describes the case where the sewing machine stops from high speed, and in such a case, the above R
The speed is actually measured while repeating the speed setting according to M25, and after the point where the actual measured value becomes less than the set speed, the control is switched to sequential control, the set speed is sequentially lowered, and the needle position signal "ND" is When the front edge is detected, the RM26 is selected and the set speed is lowered according to the rotational angle position, and after reaching the set speed of the reference speed before the needle position signal "ND", the sewing machine is started at the front edge. This is done by stopping the needle at a home position, that is, at the needle up position or needle down position selected by the switch 22. In addition, RM24 in Fig. 6
The needle fixed position stop control from a speed below the setting based on is performed by suddenly braking according to the setting speed of the RM26.

The above-mentioned stopping process from high speed is shown in FIG. 8 as a time chart. The figure shows a case where the sewing machine performs the needle fixed position stop control from a high speed, and in such a case, the setting based on RM25 is repeated according to the actually measured rotation angle position, During this time, the brake coil is fully energized and the sewing machine is decelerated at the maximum inclination (negative acceleration), and at point "P ₁ " when the set speed based on RM25 is reached, the sewing machine shifts to the sequential control. RM25 and R
The speed of the sewing machine decreases according to the braking curve set by oM26, and finally stops at the determined needle position.

Here, the above-mentioned stop control to the target position is performed by RM
25 and 26, but it is also possible to increase the number of needles for higher speed control, and the object of the present invention can be achieved, but from the viewpoint of quickly stopping the needle at the target position. It is not a good idea to control the high speed side too much and make the slope gentle, but if the sequential braking control section is set one or two stitches before the target stop position as shown in the application example of the present invention. Goals are achieved most effectively.

The time _TK required for sewing one stitch before stopping in FIG. 8 can be determined by selecting the speed setting value of RM26 and changing the slope of the braking curve for one revolution. However, the maximum slope is limited by the slope when the brake coil is fully excited.

In addition, the stopping position when stopping the needle at a predetermined position varies due to variations in braking force due to variations in power supply voltage, variations in frictional force on the surface of the brake lining, etc., but the reference speed before stopping shown in the figure " It is generally clear that the range of fluctuation can be reduced by lowering N _L '', and by configuring it in this way, the present invention exhibits its effects even more. That is, this can be easily realized by increasing the constant B in equation (1) and therefore decreasing the reference speed N _L after the pedal is placed in the neutral position.

The configuration of the above-described embodiment is entirely digital, and most of it can be configured with a one-chip microcomputer.

Effects of the Invention As is clear from the above description, the present invention allows the target needle position to be stopped to be selected with a simple operation, and in the process of stopping the needle of the sewing machine at the target position, the rotation angle position and the rotational speed, and based on the actual measurement results, select the data of the conversion element that stores the braking curve data in advance, and while setting the speed, move the sewing machine to the predetermined target position according to the braking curve. According to the present invention, it is based on the idea of stopping the
The sewing time between each stitch before the final stop, which conventionally took a long time, can be shortened and kept constant.
Therefore, it has various features such as improved sewing efficiency, improved operability, further improved stop position accuracy, and can be constructed at low cost. It is very large.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing the operation of the conventional example, Fig. 2 is a block diagram showing the configuration of the present invention, Figs. 3 to 5 are explanatory diagrams of the operation of variable speed control, and Fig. 6 is the speed of the conversion element. FIG. 7 is an explanatory diagram showing an example of the configuration of setting data, FIG. 7 is an explanatory diagram showing the operation of the present invention, and FIG. 8 is an explanatory diagram showing the relationship between sewing machine speed and time of the present invention. 1... Frequency generator, 2... Needle position detector, 3
...Speed setting device, 4...Clutch coil, 5...
Brake coil, 6... Motor, 7... Stop control means, 11, 24-26... RM, 12... Data selector, 13... Frequency divider, 14... Period counter, 17... Arithmetic unit, 21 ...Preset counter, 22...Switch, 23...Position counter.

Claims (1)

[Claims] 1. A sewing machine, a motor that drives the sewing machine,
a frequency generator that generates a pulse signal with a period that changes in proportion to the rotational speed of the sewing machine; and a needle position detector that detects a plurality of needle positions of the sewing machine and outputs needle position signals corresponding to each needle position. a speed setter that outputs a stop command signal at a specified position of the pedal and outputs a speed command signal according to the separation distance from the specified position; and a speed setter that is reset by the needle position signal and counts the pulse signal and rotates. a position measuring means for outputting an angle signal, a speed detecting means for detecting the rotational speed of the sewing machine and outputting an actual speed signal, and a needle position signal reaches a maximum when the rotational angle signal passes through the rotational angle signal and reaches a minimum just before that. a speed control means for controlling the speed of the motor; and a selection means for specifying a needle position at which the motor is to be stopped; When the needle is moved to the position, the needle operates according to the speed command signal, and in the fixed position stopping process when the stop command signal is output, the selection means first resets the position measuring means. A sewing machine driving device configured to switch a position to an upper position or a lower position, operate according to a speed setting value from the converting means, and then position and stop the sewing machine at the time when the needle position signal is detected. 2. A patent in which the speed detection means includes a clock oscillator that generates clock pulse signals and a counter, and is configured to count the number of clock pulse signals during one cycle of the pulse signal of the frequency generator and output the counting result as an actual speed signal. A sewing machine driving device according to claim 1. 3 The conversion element included in the conversion means is configured with a ROM, and the address of the ROM is designated according to the position signal, and the conversion element includes a plurality of ROMs, and one of the ROMs is configured according to the actual speed signal. The sewing machine drive device according to claim 1, wherein the sewing machine drive device is configured to select one of the two.